From c3c2893f302d087ff3c1ddd3a1d4e88c03c4356b Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 22 Apr 2021 20:17:27 +0500 Subject: [PATCH 01/35] Update match checking. fn is_useful , more skeletons Specify a lifetime on pattern references impl PatStack fill impl Matrix PatStack::pop_head_constructor Index-based approach struct PatCtxt fields construction fn Fields::wildcards split wildcard fn Constructor::is_covered_by_any(..) fn Matrix::specialize_constructor(..) impl Usefulness Initial work on witness construction Reorganize files Replace match checking diagnostic Handle types of expanded patterns unit match checking go brrr --- crates/hir_ty/Cargo.toml | 1 + crates/hir_ty/src/diagnostics.rs | 2 + crates/hir_ty/src/diagnostics/expr.rs | 70 +- crates/hir_ty/src/diagnostics/pattern.rs | 36 + .../diagnostics/pattern/deconstruct_pat.rs | 627 +++++++++++++++ .../src/diagnostics/pattern/usefulness.rs | 736 ++++++++++++++++++ 6 files changed, 1471 insertions(+), 1 deletion(-) create mode 100644 crates/hir_ty/src/diagnostics/pattern.rs create mode 100644 crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs create mode 100644 crates/hir_ty/src/diagnostics/pattern/usefulness.rs diff --git a/crates/hir_ty/Cargo.toml b/crates/hir_ty/Cargo.toml index c3d02424d619..4b714c6d8e49 100644 --- a/crates/hir_ty/Cargo.toml +++ b/crates/hir_ty/Cargo.toml @@ -22,6 +22,7 @@ chalk-solve = { version = "0.68", default-features = false } chalk-ir = "0.68" chalk-recursive = "0.68" la-arena = { version = "0.2.0", path = "../../lib/arena" } +once_cell = { version = "1.5.0" } stdx = { path = "../stdx", version = "0.0.0" } hir_def = { path = "../hir_def", version = "0.0.0" } diff --git a/crates/hir_ty/src/diagnostics.rs b/crates/hir_ty/src/diagnostics.rs index 283894704473..87a3594c52c8 100644 --- a/crates/hir_ty/src/diagnostics.rs +++ b/crates/hir_ty/src/diagnostics.rs @@ -1,6 +1,8 @@ //! Type inference-based diagnostics. mod expr; +#[allow(unused)] //todo mod match_check; +mod pattern; mod unsafe_check; mod decl_check; diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index 86f82e3fa450..ea70a5f9f62b 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -62,7 +62,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> { match expr { Expr::Match { expr, arms } => { - self.validate_match(id, *expr, arms, db, self.infer.clone()); + self.validate_match2(id, *expr, arms, db, self.infer.clone()); } Expr::Call { .. } | Expr::MethodCall { .. } => { self.validate_call(db, id, expr); @@ -277,6 +277,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> { } } + #[allow(dead_code)] fn validate_match( &mut self, id: ExprId, @@ -358,6 +359,73 @@ impl<'a, 'b> ExprValidator<'a, 'b> { } } + fn validate_match2( + &mut self, + id: ExprId, + match_expr: ExprId, + arms: &[MatchArm], + db: &dyn HirDatabase, + infer: Arc, + ) { + use crate::diagnostics::pattern::usefulness; + use hir_def::HasModule; + + let (body, source_map): (Arc, Arc) = + db.body_with_source_map(self.owner); + + let match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() { + return; + } else { + &infer.type_of_expr[match_expr] + }; + eprintln!("ExprValidator::validate_match2({:?})", match_expr_ty.kind(&Interner)); + + let pattern_arena = usefulness::PatternArena::clone_from(&body.pats); + let cx = usefulness::MatchCheckCtx { + krate: self.owner.module(db.upcast()).krate(), + match_expr, + body, + infer: &infer, + db, + pattern_arena: &pattern_arena, + }; + + let m_arms: Vec<_> = arms + .iter() + .map(|arm| usefulness::MatchArm { pat: arm.pat, has_guard: arm.guard.is_some() }) + .collect(); + + let report = usefulness::compute_match_usefulness(&cx, &m_arms); + + // TODO Report unreacheble arms + // let mut catchall = None; + // for (arm_index, (arm, is_useful)) in report.arm_usefulness.iter().enumerate() { + // match is_useful{ + // Unreachable => { + // } + // Reachable(_) => {} + // } + // } + + let witnesses = report.non_exhaustiveness_witnesses; + if !witnesses.is_empty() { + if let Ok(source_ptr) = source_map.expr_syntax(id) { + let root = source_ptr.file_syntax(db.upcast()); + if let ast::Expr::MatchExpr(match_expr) = &source_ptr.value.to_node(&root) { + if let (Some(match_expr), Some(arms)) = + (match_expr.expr(), match_expr.match_arm_list()) + { + self.sink.push(MissingMatchArms { + file: source_ptr.file_id, + match_expr: AstPtr::new(&match_expr), + arms: AstPtr::new(&arms), + }) + } + } + } + } + } + fn validate_results_in_tail_expr(&mut self, body_id: ExprId, id: ExprId, db: &dyn HirDatabase) { // the mismatch will be on the whole block currently let mismatch = match self.infer.type_mismatch_for_expr(body_id) { diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs new file mode 100644 index 000000000000..28c7a244d637 --- /dev/null +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -0,0 +1,36 @@ +#![deny(elided_lifetimes_in_paths)] +#![allow(unused)] // todo remove + +mod deconstruct_pat; +pub mod usefulness; + +#[cfg(test)] +mod tests { + use crate::diagnostics::tests::check_diagnostics; + + use super::*; + + #[test] + fn unit_exhaustive() { + check_diagnostics( + r#" +fn main() { + match () { () => {} } + match () { _ => {} } +} +"#, + ); + } + + #[test] + fn unit_non_exhaustive() { + check_diagnostics( + r#" +fn main() { + match () { } + //^^ Missing match arm +} +"#, + ); + } +} diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs new file mode 100644 index 000000000000..cde04409e01d --- /dev/null +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -0,0 +1,627 @@ +use hir_def::{ + expr::{Pat, PatId}, + AttrDefId, EnumVariantId, HasModule, VariantId, +}; + +use smallvec::{smallvec, SmallVec}; + +use crate::{AdtId, Interner, Scalar, Ty, TyExt, TyKind}; + +use super::usefulness::{MatchCheckCtx, PatCtxt}; + +use self::Constructor::*; + +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub(super) enum ToDo {} + +#[derive(Clone, Debug, PartialEq, Eq)] +pub(super) struct IntRange { + range: ToDo, +} + +impl IntRange { + #[inline] + fn is_integral(ty: &Ty) -> bool { + match ty.kind(&Interner) { + TyKind::Scalar(Scalar::Char) + | TyKind::Scalar(Scalar::Int(_)) + | TyKind::Scalar(Scalar::Uint(_)) + | TyKind::Scalar(Scalar::Bool) => true, + _ => false, + } + } + + /// See `Constructor::is_covered_by` + fn is_covered_by(&self, other: &Self) -> bool { + todo!() + } +} + +/// A constructor for array and slice patterns. +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub(super) struct Slice { + todo: ToDo, +} + +impl Slice { + /// See `Constructor::is_covered_by` + fn is_covered_by(self, other: Self) -> bool { + todo!() + } +} + +/// A value can be decomposed into a constructor applied to some fields. This struct represents +/// the constructor. See also `Fields`. +/// +/// `pat_constructor` retrieves the constructor corresponding to a pattern. +/// `specialize_constructor` returns the list of fields corresponding to a pattern, given a +/// constructor. `Constructor::apply` reconstructs the pattern from a pair of `Constructor` and +/// `Fields`. +#[derive(Clone, Debug, PartialEq)] +pub(super) enum Constructor { + /// The constructor for patterns that have a single constructor, like tuples, struct patterns + /// and fixed-length arrays. + Single, + /// Enum variants. + Variant(EnumVariantId), + /// Ranges of integer literal values (`2`, `2..=5` or `2..5`). + IntRange(IntRange), + /// Array and slice patterns. + Slice(Slice), + /// Stands for constructors that are not seen in the matrix, as explained in the documentation + /// for [`SplitWildcard`]. + Missing, + /// Wildcard pattern. + Wildcard, +} + +impl Constructor { + pub(super) fn is_wildcard(&self) -> bool { + matches!(self, Wildcard) + } + + fn as_int_range(&self) -> Option<&IntRange> { + match self { + IntRange(range) => Some(range), + _ => None, + } + } + + fn as_slice(&self) -> Option { + match self { + Slice(slice) => Some(*slice), + _ => None, + } + } + + fn variant_id_for_adt(&self, adt: hir_def::AdtId, cx: &MatchCheckCtx<'_>) -> VariantId { + match *self { + Variant(id) => id.into(), + Single => { + assert!(!matches!(adt, hir_def::AdtId::EnumId(_))); + match adt { + hir_def::AdtId::EnumId(_) => unreachable!(), + hir_def::AdtId::StructId(id) => id.into(), + hir_def::AdtId::UnionId(id) => id.into(), + } + } + _ => panic!("bad constructor {:?} for adt {:?}", self, adt), + } + } + + pub(super) fn from_pat(cx: &MatchCheckCtx<'_>, pat: PatId) -> Self { + match &cx.pattern_arena.borrow()[pat] { + Pat::Bind { .. } | Pat::Wild => Wildcard, + Pat::Tuple { .. } | Pat::Ref { .. } | Pat::Box { .. } => Single, + + pat => todo!("Constructor::from_pat {:?}", pat), + // Pat::Missing => {} + // Pat::Or(_) => {} + // Pat::Record { path, args, ellipsis } => {} + // Pat::Range { start, end } => {} + // Pat::Slice { prefix, slice, suffix } => {} + // Pat::Path(_) => {} + // Pat::Lit(_) => {} + // Pat::TupleStruct { path, args, ellipsis } => {} + // Pat::ConstBlock(_) => {} + } + } + + /// Some constructors (namely `Wildcard`, `IntRange` and `Slice`) actually stand for a set of actual + /// constructors (like variants, integers or fixed-sized slices). When specializing for these + /// constructors, we want to be specialising for the actual underlying constructors. + /// Naively, we would simply return the list of constructors they correspond to. We instead are + /// more clever: if there are constructors that we know will behave the same wrt the current + /// matrix, we keep them grouped. For example, all slices of a sufficiently large length + /// will either be all useful or all non-useful with a given matrix. + /// + /// See the branches for details on how the splitting is done. + /// + /// This function may discard some irrelevant constructors if this preserves behavior and + /// diagnostics. Eg. for the `_` case, we ignore the constructors already present in the + /// matrix, unless all of them are. + pub(super) fn split<'a>( + &self, + pcx: &PatCtxt<'_>, + ctors: impl Iterator + Clone, + ) -> SmallVec<[Self; 1]> { + match self { + Wildcard => { + let mut split_wildcard = SplitWildcard::new(pcx); + split_wildcard.split(pcx, ctors); + split_wildcard.into_ctors(pcx) + } + // Fast-track if the range is trivial. In particular, we don't do the overlapping + // ranges check. + IntRange(_) => todo!("Constructor::split IntRange"), + Slice(_) => todo!("Constructor::split Slice"), + // Any other constructor can be used unchanged. + _ => smallvec![self.clone()], + } + } + + /// Returns whether `self` is covered by `other`, i.e. whether `self` is a subset of `other`. + /// For the simple cases, this is simply checking for equality. For the "grouped" constructors, + /// this checks for inclusion. + // We inline because this has a single call site in `Matrix::specialize_constructor`. + #[inline] + pub(super) fn is_covered_by(&self, pcx: &PatCtxt<'_>, other: &Self) -> bool { + // This must be kept in sync with `is_covered_by_any`. + match (self, other) { + // Wildcards cover anything + (_, Wildcard) => true, + // The missing ctors are not covered by anything in the matrix except wildcards. + (Missing, _) | (Wildcard, _) => false, + + (Single, Single) => true, + (Variant(self_id), Variant(other_id)) => self_id == other_id, + + (Constructor::IntRange(_), Constructor::IntRange(_)) => todo!(), + + (Constructor::Slice(_), Constructor::Slice(_)) => todo!(), + + _ => panic!("bug"), + } + } + + /// Faster version of `is_covered_by` when applied to many constructors. `used_ctors` is + /// assumed to be built from `matrix.head_ctors()` with wildcards filtered out, and `self` is + /// assumed to have been split from a wildcard. + fn is_covered_by_any(&self, pcx: &PatCtxt<'_>, used_ctors: &[Constructor]) -> bool { + if used_ctors.is_empty() { + return false; + } + + // This must be kept in sync with `is_covered_by`. + match self { + // If `self` is `Single`, `used_ctors` cannot contain anything else than `Single`s. + Single => !used_ctors.is_empty(), + Variant(_) => used_ctors.iter().any(|c| c == self), + IntRange(range) => used_ctors + .iter() + .filter_map(|c| c.as_int_range()) + .any(|other| range.is_covered_by(other)), + Slice(slice) => used_ctors + .iter() + .filter_map(|c| c.as_slice()) + .any(|other| slice.is_covered_by(other)), + + _ => todo!(), + } + } +} + +/// A wildcard constructor that we split relative to the constructors in the matrix, as explained +/// at the top of the file. +/// +/// A constructor that is not present in the matrix rows will only be covered by the rows that have +/// wildcards. Thus we can group all of those constructors together; we call them "missing +/// constructors". Splitting a wildcard would therefore list all present constructors individually +/// (or grouped if they are integers or slices), and then all missing constructors together as a +/// group. +/// +/// However we can go further: since any constructor will match the wildcard rows, and having more +/// rows can only reduce the amount of usefulness witnesses, we can skip the present constructors +/// and only try the missing ones. +/// This will not preserve the whole list of witnesses, but will preserve whether the list is empty +/// or not. In fact this is quite natural from the point of view of diagnostics too. This is done +/// in `to_ctors`: in some cases we only return `Missing`. +#[derive(Debug)] +pub(super) struct SplitWildcard { + /// Constructors seen in the matrix. + matrix_ctors: Vec, + /// All the constructors for this type + all_ctors: SmallVec<[Constructor; 1]>, +} + +impl SplitWildcard { + pub(super) fn new(pcx: &PatCtxt<'_>) -> Self { + // let cx = pcx.cx; + // let make_range = |start, end| IntRange(todo!()); + + // This determines the set of all possible constructors for the type `pcx.ty`. For numbers, + // arrays and slices we use ranges and variable-length slices when appropriate. + // + // If the `exhaustive_patterns` feature is enabled, we make sure to omit constructors that + // are statically impossible. E.g., for `Option`, we do not include `Some(_)` in the + // returned list of constructors. + // Invariant: this is empty if and only if the type is uninhabited (as determined by + // `cx.is_uninhabited()`). + let all_ctors = match pcx.ty.kind(&Interner) { + TyKind::Adt(AdtId(hir_def::AdtId::EnumId(_)), _) => todo!(), + TyKind::Adt(..) | TyKind::Tuple(..) | TyKind::Ref(..) => smallvec![Single], + _ => todo!(), + }; + SplitWildcard { matrix_ctors: Vec::new(), all_ctors } + } + + /// Pass a set of constructors relative to which to split this one. Don't call twice, it won't + /// do what you want. + pub(super) fn split<'a>( + &mut self, + pcx: &PatCtxt<'_>, + ctors: impl Iterator + Clone, + ) { + // Since `all_ctors` never contains wildcards, this won't recurse further. + self.all_ctors = + self.all_ctors.iter().flat_map(|ctor| ctor.split(pcx, ctors.clone())).collect(); + self.matrix_ctors = ctors.filter(|c| !c.is_wildcard()).cloned().collect(); + } + + /// Whether there are any value constructors for this type that are not present in the matrix. + fn any_missing(&self, pcx: &PatCtxt<'_>) -> bool { + self.iter_missing(pcx).next().is_some() + } + + /// Iterate over the constructors for this type that are not present in the matrix. + pub(super) fn iter_missing<'a>( + &'a self, + pcx: &'a PatCtxt<'_>, + ) -> impl Iterator { + self.all_ctors.iter().filter(move |ctor| !ctor.is_covered_by_any(pcx, &self.matrix_ctors)) + } + + /// Return the set of constructors resulting from splitting the wildcard. As explained at the + /// top of the file, if any constructors are missing we can ignore the present ones. + fn into_ctors(self, pcx: &PatCtxt<'_>) -> SmallVec<[Constructor; 1]> { + if self.any_missing(pcx) { + // Some constructors are missing, thus we can specialize with the special `Missing` + // constructor, which stands for those constructors that are not seen in the matrix, + // and matches the same rows as any of them (namely the wildcard rows). See the top of + // the file for details. + // However, when all constructors are missing we can also specialize with the full + // `Wildcard` constructor. The difference will depend on what we want in diagnostics. + + // If some constructors are missing, we typically want to report those constructors, + // e.g.: + // ``` + // enum Direction { N, S, E, W } + // let Direction::N = ...; + // ``` + // we can report 3 witnesses: `S`, `E`, and `W`. + // + // However, if the user didn't actually specify a constructor + // in this arm, e.g., in + // ``` + // let x: (Direction, Direction, bool) = ...; + // let (_, _, false) = x; + // ``` + // we don't want to show all 16 possible witnesses `(, , + // true)` - we are satisfied with `(_, _, true)`. So if all constructors are missing we + // prefer to report just a wildcard `_`. + // + // The exception is: if we are at the top-level, for example in an empty match, we + // sometimes prefer reporting the list of constructors instead of just `_`. + + let report_when_all_missing = pcx.is_top_level && !IntRange::is_integral(&pcx.ty); + let ctor = if !self.matrix_ctors.is_empty() || report_when_all_missing { + Missing + } else { + Wildcard + }; + return smallvec![ctor]; + } + + // All the constructors are present in the matrix, so we just go through them all. + self.all_ctors + } +} + +#[test] +fn it_works2() {} + +/// Some fields need to be explicitly hidden away in certain cases; see the comment above the +/// `Fields` struct. This struct represents such a potentially-hidden field. +#[derive(Debug, Copy, Clone)] +pub(super) enum FilteredField { + Kept(PatId), + Hidden, +} + +impl FilteredField { + fn kept(self) -> Option { + match self { + FilteredField::Kept(p) => Some(p), + FilteredField::Hidden => None, + } + } +} + +/// A value can be decomposed into a constructor applied to some fields. This struct represents +/// those fields, generalized to allow patterns in each field. See also `Constructor`. +/// This is constructed from a constructor using [`Fields::wildcards()`]. +/// +/// If a private or `non_exhaustive` field is uninhabited, the code mustn't observe that it is +/// uninhabited. For that, we filter these fields out of the matrix. This is handled automatically +/// in `Fields`. This filtering is uncommon in practice, because uninhabited fields are rarely used, +/// so we avoid it when possible to preserve performance. +#[derive(Debug, Clone)] +pub(super) enum Fields { + /// Lists of patterns that don't contain any filtered fields. + /// `Slice` and `Vec` behave the same; the difference is only to avoid allocating and + /// triple-dereferences when possible. Frankly this is premature optimization, I (Nadrieril) + /// have not measured if it really made a difference. + Vec(SmallVec<[PatId; 2]>), +} + +impl Fields { + /// Internal use. Use `Fields::wildcards()` instead. + /// Must not be used if the pattern is a field of a struct/tuple/variant. + fn from_single_pattern(pat: PatId) -> Self { + Fields::Vec(smallvec![pat]) + } + + /// Convenience; internal use. + fn wildcards_from_tys<'a>( + cx: &MatchCheckCtx<'_>, + tys: impl IntoIterator, + ) -> Self { + let wilds = tys.into_iter().map(|ty| (Pat::Wild, ty)); + let pats = wilds.map(|(pat, ty)| cx.alloc_pat(pat, ty)).collect(); + Fields::Vec(pats) + } + + pub(crate) fn wildcards(pcx: &PatCtxt<'_>, constructor: &Constructor) -> Self { + let ty = &pcx.ty; + let cx = pcx.cx; + let wildcard_from_ty = |ty| cx.alloc_pat(Pat::Wild, ty); + + let ret = match constructor { + Single | Variant(_) => match ty.kind(&Interner) { + TyKind::Tuple(_, substs) => { + let tys = substs.iter(&Interner).map(|ty| ty.assert_ty_ref(&Interner)); + Fields::wildcards_from_tys(cx, tys) + } + TyKind::Ref(.., rty) => Fields::from_single_pattern(wildcard_from_ty(rty)), + TyKind::Adt(AdtId(adt), substs) => { + let adt_is_box = false; // TODO(iDawer): handle box patterns + if adt_is_box { + // Use T as the sub pattern type of Box. + let ty = substs.at(&Interner, 0).assert_ty_ref(&Interner); + Fields::from_single_pattern(wildcard_from_ty(ty)) + } else { + let variant_id = constructor.variant_id_for_adt(*adt, cx); + let variant = variant_id.variant_data(cx.db.upcast()); + let adt_is_local = variant_id.module(cx.db.upcast()).krate() == cx.krate; + // Whether we must not match the fields of this variant exhaustively. + let is_non_exhaustive = + is_field_list_non_exhaustive(variant_id, cx) && !adt_is_local; + let field_ty_arena = cx.db.field_types(variant_id); + let field_tys = + || field_ty_arena.iter().map(|(_, binders)| binders.skip_binders()); + // In the following cases, we don't need to filter out any fields. This is + // the vast majority of real cases, since uninhabited fields are uncommon. + let has_no_hidden_fields = (matches!(adt, hir_def::AdtId::EnumId(_)) + && !is_non_exhaustive) + || !field_tys().any(|ty| cx.is_uninhabited(ty)); + + if has_no_hidden_fields { + Fields::wildcards_from_tys(cx, field_tys()) + } else { + //FIXME(iDawer): see MatchCheckCtx::is_uninhabited + unimplemented!("exhaustive_patterns feature") + } + } + } + _ => panic!("Unexpected type for `Single` constructor: {:?}", ty), + }, + Missing | Wildcard => Fields::Vec(Default::default()), + _ => todo!(), + }; + ret + } + + /// Apply a constructor to a list of patterns, yielding a new pattern. `self` + /// must have as many elements as this constructor's arity. + /// + /// This is roughly the inverse of `specialize_constructor`. + /// + /// Examples: + /// `ctor`: `Constructor::Single` + /// `ty`: `Foo(u32, u32, u32)` + /// `self`: `[10, 20, _]` + /// returns `Foo(10, 20, _)` + /// + /// `ctor`: `Constructor::Variant(Option::Some)` + /// `ty`: `Option` + /// `self`: `[false]` + /// returns `Some(false)` + pub(super) fn apply(self, pcx: &PatCtxt<'_>, ctor: &Constructor) -> Pat { + let subpatterns_and_indices = self.patterns_and_indices(); + let mut subpatterns = subpatterns_and_indices.iter().map(|&(_, p)| p); + + match ctor { + Single | Variant(_) => match pcx.ty.kind(&Interner) { + TyKind::Adt(..) | TyKind::Tuple(..) => { + // We want the real indices here. + // TODO indices + let subpatterns = subpatterns_and_indices.iter().map(|&(_, pat)| pat).collect(); + + if let Some((adt, substs)) = pcx.ty.as_adt() { + if let hir_def::AdtId::EnumId(_) = adt { + todo!() + } else { + todo!() + } + } else { + // TODO ellipsis + Pat::Tuple { args: subpatterns, ellipsis: None } + } + } + + _ => todo!(), + // TyKind::AssociatedType(_, _) => {} + // TyKind::Scalar(_) => {} + // TyKind::Array(_, _) => {} + // TyKind::Slice(_) => {} + // TyKind::Raw(_, _) => {} + // TyKind::Ref(_, _, _) => {} + // TyKind::OpaqueType(_, _) => {} + // TyKind::FnDef(_, _) => {} + // TyKind::Str => {} + // TyKind::Never => {} + // TyKind::Closure(_, _) => {} + // TyKind::Generator(_, _) => {} + // TyKind::GeneratorWitness(_, _) => {} + // TyKind::Foreign(_) => {} + // TyKind::Error => {} + // TyKind::Placeholder(_) => {} + // TyKind::Dyn(_) => {} + // TyKind::Alias(_) => {} + // TyKind::Function(_) => {} + // TyKind::BoundVar(_) => {} + // TyKind::InferenceVar(_, _) => {} + }, + + _ => todo!(), + // Constructor::IntRange(_) => {} + // Constructor::Slice(_) => {} + // Missing => {} + // Wildcard => {} + } + } + + /// Returns the number of patterns. This is the same as the arity of the constructor used to + /// construct `self`. + pub(super) fn len(&self) -> usize { + match self { + Fields::Vec(pats) => pats.len(), + } + } + + /// Returns the list of patterns along with the corresponding field indices. + fn patterns_and_indices(&self) -> SmallVec<[(usize, PatId); 2]> { + match self { + Fields::Vec(pats) => pats.iter().copied().enumerate().collect(), + } + } + + pub(super) fn into_patterns(self) -> SmallVec<[PatId; 2]> { + match self { + Fields::Vec(pats) => pats, + } + } + + /// Overrides some of the fields with the provided patterns. Exactly like + /// `replace_fields_indexed`, except that it takes `FieldPat`s as input. + fn replace_with_fieldpats(&self, new_pats: impl IntoIterator) -> Self { + self.replace_fields_indexed(new_pats.into_iter().enumerate()) + } + + /// Overrides some of the fields with the provided patterns. This is used when a pattern + /// defines some fields but not all, for example `Foo { field1: Some(_), .. }`: here we start + /// with a `Fields` that is just one wildcard per field of the `Foo` struct, and override the + /// entry corresponding to `field1` with the pattern `Some(_)`. This is also used for slice + /// patterns for the same reason. + fn replace_fields_indexed(&self, new_pats: impl IntoIterator) -> Self { + let mut fields = self.clone(); + + match &mut fields { + Fields::Vec(pats) => { + for (i, pat) in new_pats { + if let Some(p) = pats.get_mut(i) { + *p = pat; + } + } + } + } + fields + } + + /// Replaces contained fields with the given list of patterns. There must be `len()` patterns + /// in `pats`. + pub(super) fn replace_fields( + &self, + cx: &MatchCheckCtx<'_>, + pats: impl IntoIterator, + ) -> Self { + let pats = { + let mut arena = cx.pattern_arena.borrow_mut(); + pats.into_iter().map(move |pat| /* arena.alloc(pat) */ todo!()).collect() + }; + + match self { + Fields::Vec(_) => Fields::Vec(pats), + } + } + + /// Replaces contained fields with the arguments of the given pattern. Only use on a pattern + /// that is compatible with the constructor used to build `self`. + /// This is meant to be used on the result of `Fields::wildcards()`. The idea is that + /// `wildcards` constructs a list of fields where all entries are wildcards, and the pattern + /// provided to this function fills some of the fields with non-wildcards. + /// In the following example `Fields::wildcards` would return `[_, _, _, _]`. If we call + /// `replace_with_pattern_arguments` on it with the pattern, the result will be `[Some(0), _, + /// _, _]`. + /// ```rust + /// let x: [Option; 4] = foo(); + /// match x { + /// [Some(0), ..] => {} + /// } + /// ``` + /// This is guaranteed to preserve the number of patterns in `self`. + pub(super) fn replace_with_pattern_arguments( + &self, + pat: PatId, + cx: &MatchCheckCtx<'_>, + ) -> Self { + match &cx.pattern_arena.borrow()[pat] { + Pat::Ref { pat: subpattern, .. } => { + assert_eq!(self.len(), 1); + Fields::from_single_pattern(*subpattern) + } + Pat::Tuple { args: subpatterns, ellipsis } => { + // FIXME(iDawer) handle ellipsis. + // XXX(iDawer): in rustc, this is handled by HIR->TypedHIR lowering + // rustc_mir_build::thir::pattern::PatCtxt::lower_tuple_subpats(..) + self.replace_with_fieldpats(subpatterns.iter().copied()) + } + + Pat::Wild => self.clone(), + pat => todo!("Fields::replace_with_pattern_arguments({:?})", pat), + // Pat::Missing => {} + // Pat::Or(_) => {} + // Pat::Record { path, args, ellipsis } => {} + // Pat::Range { start, end } => {} + // Pat::Slice { prefix, slice, suffix } => {} + // Pat::Path(_) => {} + // Pat::Lit(_) => {} + // Pat::Bind { mode, name, subpat } => {} + // Pat::TupleStruct { path, args, ellipsis } => {} + // Pat::Box { inner } => {} + // Pat::ConstBlock(_) => {} + } + } +} + +fn is_field_list_non_exhaustive(variant_id: VariantId, cx: &MatchCheckCtx<'_>) -> bool { + let attr_def_id = match variant_id { + VariantId::EnumVariantId(id) => id.into(), + VariantId::StructId(id) => id.into(), + VariantId::UnionId(id) => id.into(), + }; + cx.db.attrs(attr_def_id).by_key("non_exhaustive").exists() +} + +#[test] +fn it_works() {} diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs new file mode 100644 index 000000000000..f5f6bf494953 --- /dev/null +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -0,0 +1,736 @@ +// Based on rust-lang/rust 1.52.0-nightly (25c15cdbe 2021-04-22) +// rust/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs + +use std::{cell::RefCell, iter::FromIterator, ops::Index, sync::Arc}; + +use base_db::CrateId; +use hir_def::{ + body::Body, + expr::{ExprId, Pat, PatId}, +}; +use la_arena::Arena; +use once_cell::unsync::OnceCell; +use rustc_hash::FxHashMap; +use smallvec::{smallvec, SmallVec}; + +use crate::{db::HirDatabase, InferenceResult, Ty}; + +use super::deconstruct_pat::{Constructor, Fields, SplitWildcard}; + +use self::{ + helper::{Captures, PatIdExt}, + Usefulness::*, + WitnessPreference::*, +}; + +pub(crate) struct MatchCheckCtx<'a> { + pub(crate) krate: CrateId, + pub(crate) match_expr: ExprId, + pub(crate) body: Arc, + pub(crate) infer: &'a InferenceResult, + pub(crate) db: &'a dyn HirDatabase, + /// Patterns from self.body.pats plus generated by the check. + pub(crate) pattern_arena: &'a RefCell, +} + +impl<'a> MatchCheckCtx<'a> { + pub(super) fn is_uninhabited(&self, ty: &Ty) -> bool { + // FIXME(iDawer) implement exhaustive_patterns feature. More info in: + // Tracking issue for RFC 1872: exhaustive_patterns feature https://github.com/rust-lang/rust/issues/51085 + false + } + + pub(super) fn alloc_pat(&self, pat: Pat, ty: &Ty) -> PatId { + self.pattern_arena.borrow_mut().alloc(pat, ty) + } + + /// Get type of a pattern. Handles expanded patterns. + pub(super) fn type_of(&self, pat: PatId) -> Ty { + let type_of_expanded_pat = self.pattern_arena.borrow().type_of_epat.get(&pat).cloned(); + type_of_expanded_pat.unwrap_or_else(|| self.infer[pat].clone()) + } +} + +#[derive(Clone)] +pub(super) struct PatCtxt<'a> { + pub(super) cx: &'a MatchCheckCtx<'a>, + /// Type of the current column under investigation. + pub(super) ty: Ty, + /// Whether the current pattern is the whole pattern as found in a match arm, or if it's a + /// subpattern. + pub(super) is_top_level: bool, +} + +impl PatIdExt for PatId { + fn is_wildcard(self, cx: &MatchCheckCtx<'_>) -> bool { + matches!(cx.pattern_arena.borrow()[self], Pat::Bind { subpat: None, .. } | Pat::Wild) + } + + fn is_or_pat(self, cx: &MatchCheckCtx<'_>) -> bool { + matches!(cx.pattern_arena.borrow()[self], Pat::Or(..)) + } + + /// Recursively expand this pattern into its subpatterns. Only useful for or-patterns. + fn expand_or_pat(self, cx: &MatchCheckCtx<'_>) -> Vec { + fn expand(pat: PatId, vec: &mut Vec, pat_arena: &PatternArena) { + if let Pat::Or(pats) = &pat_arena[pat] { + for &pat in pats { + expand(pat, vec, pat_arena); + } + } else { + vec.push(pat) + } + } + + let pat_arena = cx.pattern_arena.borrow(); + let mut pats = Vec::new(); + expand(self, &mut pats, &pat_arena); + pats + } +} + +/// A row of a matrix. Rows of len 1 are very common, which is why `SmallVec[_; 2]` +/// works well. +#[derive(Clone)] +pub(super) struct PatStack { + pats: SmallVec<[PatId; 2]>, + /// Cache for the constructor of the head + head_ctor: OnceCell, +} + +impl PatStack { + fn from_pattern(pat: PatId) -> Self { + Self::from_vec(smallvec![pat]) + } + + fn from_vec(vec: SmallVec<[PatId; 2]>) -> Self { + PatStack { pats: vec, head_ctor: OnceCell::new() } + } + + fn is_empty(&self) -> bool { + self.pats.is_empty() + } + + fn len(&self) -> usize { + self.pats.len() + } + + fn head(&self) -> PatId { + self.pats[0] + } + + #[inline] + fn head_ctor(&self, cx: &MatchCheckCtx<'_>) -> &Constructor { + self.head_ctor.get_or_init(|| Constructor::from_pat(cx, self.head())) + } + + fn iter(&self) -> impl Iterator + '_ { + self.pats.iter().copied() + } + + // Recursively expand the first pattern into its subpatterns. Only useful if the pattern is an + // or-pattern. Panics if `self` is empty. + fn expand_or_pat(&self, cx: &MatchCheckCtx<'_>) -> impl Iterator + '_ { + self.head().expand_or_pat(cx).into_iter().map(move |pat| { + let mut new_patstack = PatStack::from_pattern(pat); + new_patstack.pats.extend_from_slice(&self.pats[1..]); + new_patstack + }) + } + + /// This computes `S(self.head_ctor(), self)`. See top of the file for explanations. + /// + /// Structure patterns with a partial wild pattern (Foo { a: 42, .. }) have their missing + /// fields filled with wild patterns. + /// + /// This is roughly the inverse of `Constructor::apply`. + fn pop_head_constructor( + &self, + ctor_wild_subpatterns: &Fields, + cx: &MatchCheckCtx<'_>, + ) -> PatStack { + // We pop the head pattern and push the new fields extracted from the arguments of + // `self.head()`. + let mut new_fields = + ctor_wild_subpatterns.replace_with_pattern_arguments(self.head(), cx).into_patterns(); + new_fields.extend_from_slice(&self.pats[1..]); + PatStack::from_vec(new_fields) + } +} + +impl Default for PatStack { + fn default() -> Self { + Self::from_vec(smallvec![]) + } +} + +impl PartialEq for PatStack { + fn eq(&self, other: &Self) -> bool { + self.pats == other.pats + } +} + +impl FromIterator for PatStack { + fn from_iter(iter: T) -> Self + where + T: IntoIterator, + { + Self::from_vec(iter.into_iter().collect()) + } +} + +#[derive(Clone)] +pub(super) struct Matrix { + patterns: Vec, +} + +impl Matrix { + fn empty() -> Self { + Matrix { patterns: vec![] } + } + + /// Number of columns of this matrix. `None` is the matrix is empty. + pub(super) fn column_count(&self) -> Option { + self.patterns.get(0).map(|r| r.len()) + } + + /// Pushes a new row to the matrix. If the row starts with an or-pattern, this recursively + /// expands it. + fn push(&mut self, row: PatStack, cx: &MatchCheckCtx<'_>) { + if !row.is_empty() && row.head().is_or_pat(cx) { + for row in row.expand_or_pat(cx) { + self.patterns.push(row); + } + } else { + self.patterns.push(row); + } + } + + /// Iterate over the first component of each row + fn heads(&self) -> impl Iterator + '_ { + self.patterns.iter().map(|r| r.head()) + } + + /// Iterate over the first constructor of each row. + fn head_ctors<'a>( + &'a self, + cx: &'a MatchCheckCtx<'_>, + ) -> impl Iterator + Clone { + self.patterns.iter().map(move |r| r.head_ctor(cx)) + } + + /// This computes `S(constructor, self)`. See top of the file for explanations. + fn specialize_constructor( + &self, + pcx: &PatCtxt<'_>, + ctor: &Constructor, + ctor_wild_subpatterns: &Fields, + ) -> Matrix { + let rows = self + .patterns + .iter() + .filter(|r| ctor.is_covered_by(pcx, r.head_ctor(pcx.cx))) + .map(|r| r.pop_head_constructor(ctor_wild_subpatterns, pcx.cx)); + Matrix::from_iter(rows, pcx.cx) + } + + fn from_iter(rows: impl IntoIterator, cx: &MatchCheckCtx<'_>) -> Matrix { + let mut matrix = Matrix::empty(); + for x in rows { + // Using `push` ensures we correctly expand or-patterns. + matrix.push(x, cx); + } + matrix + } +} + +#[derive(Debug, Clone)] +enum SubPatSet { + /// The empty set. This means the pattern is unreachable. + Empty, + /// The set containing the full pattern. + Full, + /// If the pattern is a pattern with a constructor or a pattern-stack, we store a set for each + /// of its subpatterns. Missing entries in the map are implicitly full, because that's the + /// common case. + Seq { subpats: FxHashMap }, + /// If the pattern is an or-pattern, we store a set for each of its alternatives. Missing + /// entries in the map are implicitly empty. Note: we always flatten nested or-patterns. + Alt { + subpats: FxHashMap, + /// Counts the total number of alternatives in the pattern + alt_count: usize, + /// We keep the pattern around to retrieve spans. + pat: PatId, + }, +} + +impl SubPatSet { + fn full() -> Self { + SubPatSet::Full + } + + fn empty() -> Self { + SubPatSet::Empty + } + + fn is_empty(&self) -> bool { + match self { + SubPatSet::Empty => true, + SubPatSet::Full => false, + // If any subpattern in a sequence is unreachable, the whole pattern is unreachable. + SubPatSet::Seq { subpats } => subpats.values().any(|set| set.is_empty()), + // An or-pattern is reachable if any of its alternatives is. + SubPatSet::Alt { subpats, .. } => subpats.values().all(|set| set.is_empty()), + } + } + + fn is_full(&self) -> bool { + match self { + SubPatSet::Empty => false, + SubPatSet::Full => true, + // The whole pattern is reachable only when all its alternatives are. + SubPatSet::Seq { subpats } => subpats.values().all(|sub_set| sub_set.is_full()), + // The whole or-pattern is reachable only when all its alternatives are. + SubPatSet::Alt { subpats, alt_count, .. } => { + subpats.len() == *alt_count && subpats.values().all(|set| set.is_full()) + } + } + } + + /// Union `self` with `other`, mutating `self`. + fn union(&mut self, other: Self) { + use SubPatSet::*; + // Union with full stays full; union with empty changes nothing. + if self.is_full() || other.is_empty() { + return; + } else if self.is_empty() { + *self = other; + return; + } else if other.is_full() { + *self = Full; + return; + } + + match (&mut *self, other) { + (Seq { .. }, Seq { .. }) => { + todo!() + } + (Alt { .. }, Alt { .. }) => { + todo!() + } + _ => panic!("bug"), + } + } + + /// Returns a list of the spans of the unreachable subpatterns. If `self` is empty (i.e. the + /// whole pattern is unreachable) we return `None`. + fn list_unreachable_spans(&self) -> Option> { + if self.is_empty() { + return None; + } + if self.is_full() { + // No subpatterns are unreachable. + return Some(Vec::new()); + } + todo!() + } + + /// When `self` refers to a patstack that was obtained from specialization, after running + /// `unspecialize` it will refer to the original patstack before specialization. + fn unspecialize(self, arity: usize) -> Self { + use SubPatSet::*; + match self { + Full => Full, + Empty => Empty, + Seq { subpats } => { + todo!() + } + Alt { .. } => panic!("bug"), + } + } + + /// When `self` refers to a patstack that was obtained from splitting an or-pattern, after + /// running `unspecialize` it will refer to the original patstack before splitting. + /// + /// For example: + /// ``` + /// match Some(true) { + /// Some(true) => {} + /// None | Some(true | false) => {} + /// } + /// ``` + /// Here `None` would return the full set and `Some(true | false)` would return the set + /// containing `false`. After `unsplit_or_pat`, we want the set to contain `None` and `false`. + /// This is what this function does. + fn unsplit_or_pat(mut self, alt_id: usize, alt_count: usize, pat: PatId) -> Self { + todo!() + } +} + +/// This carries the results of computing usefulness, as described at the top of the file. When +/// checking usefulness of a match branch, we use the `NoWitnesses` variant, which also keeps track +/// of potential unreachable sub-patterns (in the presence of or-patterns). When checking +/// exhaustiveness of a whole match, we use the `WithWitnesses` variant, which carries a list of +/// witnesses of non-exhaustiveness when there are any. +/// Which variant to use is dictated by `WitnessPreference`. +#[derive(Clone, Debug)] +enum Usefulness { + /// Carries a set of subpatterns that have been found to be reachable. If empty, this indicates + /// the whole pattern is unreachable. If not, this indicates that the pattern is reachable but + /// that some sub-patterns may be unreachable (due to or-patterns). In the absence of + /// or-patterns this will always be either `Empty` (the whole pattern is unreachable) or `Full` + /// (the whole pattern is reachable). + NoWitnesses(SubPatSet), + /// Carries a list of witnesses of non-exhaustiveness. If empty, indicates that the whole + /// pattern is unreachable. + WithWitnesses(Vec), +} + +impl Usefulness { + fn new_useful(preference: WitnessPreference) -> Self { + match preference { + ConstructWitness => WithWitnesses(vec![Witness(vec![])]), + LeaveOutWitness => NoWitnesses(SubPatSet::full()), + } + } + fn new_not_useful(preference: WitnessPreference) -> Self { + match preference { + ConstructWitness => WithWitnesses(vec![]), + LeaveOutWitness => NoWitnesses(SubPatSet::empty()), + } + } + + /// Combine usefulnesses from two branches. This is an associative operation. + fn extend(&mut self, other: Self) { + match (&mut *self, other) { + (WithWitnesses(_), WithWitnesses(o)) if o.is_empty() => {} + (WithWitnesses(s), WithWitnesses(o)) if s.is_empty() => *self = WithWitnesses(o), + (WithWitnesses(s), WithWitnesses(o)) => s.extend(o), + (NoWitnesses(s), NoWitnesses(o)) => s.union(o), + _ => unreachable!(), + } + } + + /// When trying several branches and each returns a `Usefulness`, we need to combine the + /// results together. + fn merge(pref: WitnessPreference, usefulnesses: impl Iterator) -> Self { + let mut ret = Self::new_not_useful(pref); + for u in usefulnesses { + ret.extend(u); + if let NoWitnesses(subpats) = &ret { + if subpats.is_full() { + // Once we reach the full set, more unions won't change the result. + return ret; + } + } + } + ret + } + + /// After calculating the usefulness for a branch of an or-pattern, call this to make this + /// usefulness mergeable with those from the other branches. + fn unsplit_or_pat(self, alt_id: usize, alt_count: usize, pat: PatId) -> Self { + match self { + NoWitnesses(subpats) => NoWitnesses(subpats.unsplit_or_pat(alt_id, alt_count, pat)), + WithWitnesses(_) => panic!("bug"), + } + } + + /// After calculating usefulness after a specialization, call this to recontruct a usefulness + /// that makes sense for the matrix pre-specialization. This new usefulness can then be merged + /// with the results of specializing with the other constructors. + fn apply_constructor( + self, + pcx: &PatCtxt<'_>, + matrix: &Matrix, + ctor: &Constructor, + ctor_wild_subpatterns: &Fields, + ) -> Self { + match self { + WithWitnesses(witnesses) if witnesses.is_empty() => WithWitnesses(witnesses), + WithWitnesses(w) => { + let new_witnesses = if matches!(ctor, Constructor::Missing) { + let mut split_wildcard = SplitWildcard::new(pcx); + split_wildcard.split(pcx, matrix.head_ctors(pcx.cx)); + } else { + todo!("Usefulness::apply_constructor({:?})", ctor) + }; + todo!("Usefulness::apply_constructor({:?})", ctor) + } + NoWitnesses(subpats) => NoWitnesses(subpats.unspecialize(ctor_wild_subpatterns.len())), + } + } +} + +#[derive(Copy, Clone, Debug)] +enum WitnessPreference { + ConstructWitness, + LeaveOutWitness, +} + +#[derive(Clone, Debug)] +pub(crate) struct Witness(Vec); + +impl Witness { + /// Asserts that the witness contains a single pattern, and returns it. + fn single_pattern(self) -> Pat { + assert_eq!(self.0.len(), 1); + self.0.into_iter().next().unwrap() + } + + /// Constructs a partial witness for a pattern given a list of + /// patterns expanded by the specialization step. + /// + /// When a pattern P is discovered to be useful, this function is used bottom-up + /// to reconstruct a complete witness, e.g., a pattern P' that covers a subset + /// of values, V, where each value in that set is not covered by any previously + /// used patterns and is covered by the pattern P'. Examples: + /// + /// left_ty: tuple of 3 elements + /// pats: [10, 20, _] => (10, 20, _) + /// + /// left_ty: struct X { a: (bool, &'static str), b: usize} + /// pats: [(false, "foo"), 42] => X { a: (false, "foo"), b: 42 } + fn apply_constructor( + mut self, + pcx: &PatCtxt<'_>, + ctor: &Constructor, + ctor_wild_subpatterns: &Fields, + ) -> Self { + let pat = { + let len = self.0.len(); + let arity = ctor_wild_subpatterns.len(); + let pats = self.0.drain((len - arity)..).rev(); + ctor_wild_subpatterns.replace_fields(pcx.cx, pats).apply(pcx, ctor) + }; + + self.0.push(pat); + + self + } +} + +/// Algorithm from . +/// The algorithm from the paper has been modified to correctly handle empty +/// types. The changes are: +/// (0) We don't exit early if the pattern matrix has zero rows. We just +/// continue to recurse over columns. +/// (1) all_constructors will only return constructors that are statically +/// possible. E.g., it will only return `Ok` for `Result`. +/// +/// This finds whether a (row) vector `v` of patterns is 'useful' in relation +/// to a set of such vectors `m` - this is defined as there being a set of +/// inputs that will match `v` but not any of the sets in `m`. +/// +/// All the patterns at each column of the `matrix ++ v` matrix must have the same type. +/// +/// This is used both for reachability checking (if a pattern isn't useful in +/// relation to preceding patterns, it is not reachable) and exhaustiveness +/// checking (if a wildcard pattern is useful in relation to a matrix, the +/// matrix isn't exhaustive). +/// +/// `is_under_guard` is used to inform if the pattern has a guard. If it +/// has one it must not be inserted into the matrix. This shouldn't be +/// relied on for soundness. +fn is_useful( + cx: &MatchCheckCtx<'_>, + matrix: &Matrix, + v: &PatStack, + witness_preference: WitnessPreference, + is_under_guard: bool, + is_top_level: bool, +) -> Usefulness { + let Matrix { patterns: rows, .. } = matrix; + + // The base case. We are pattern-matching on () and the return value is + // based on whether our matrix has a row or not. + // NOTE: This could potentially be optimized by checking rows.is_empty() + // first and then, if v is non-empty, the return value is based on whether + // the type of the tuple we're checking is inhabited or not. + if v.is_empty() { + let ret = if rows.is_empty() { + Usefulness::new_useful(witness_preference) + } else { + Usefulness::new_not_useful(witness_preference) + }; + return ret; + } + + assert!(rows.iter().all(|r| r.len() == v.len())); + + // FIXME(Nadrieril): Hack to work around type normalization issues (see rust-lang/rust#72476). + // TODO(iDawer): ty.as_reference() + let ty = matrix.heads().next().map_or(cx.type_of(v.head()), |r| cx.type_of(r)); + let pcx = PatCtxt { cx, ty, is_top_level }; + + // If the first pattern is an or-pattern, expand it. + let ret = if v.head().is_or_pat(cx) { + //expanding or-pattern + let v_head = v.head(); + let vs: Vec<_> = v.expand_or_pat(cx).collect(); + let alt_count = vs.len(); + // We try each or-pattern branch in turn. + let mut matrix = matrix.clone(); + let usefulnesses = vs.into_iter().enumerate().map(|(i, v)| { + let usefulness = is_useful(cx, &matrix, &v, witness_preference, is_under_guard, false); + // If pattern has a guard don't add it to the matrix. + if !is_under_guard { + // We push the already-seen patterns into the matrix in order to detect redundant + // branches like `Some(_) | Some(0)`. + matrix.push(v, cx); + } + usefulness.unsplit_or_pat(i, alt_count, v_head) + }); + Usefulness::merge(witness_preference, usefulnesses) + } else { + let v_ctor = v.head_ctor(cx); + // if let Constructor::IntRange(ctor_range) = v_ctor { + // // Lint on likely incorrect range patterns (#63987) + // ctor_range.lint_overlapping_range_endpoints( + // pcx, + // matrix.head_ctors_and_spans(cx), + // matrix.column_count().unwrap_or(0), + // hir_id, + // ) + // } + + // We split the head constructor of `v`. + let split_ctors = v_ctor.split(&pcx, matrix.head_ctors(cx)); + // For each constructor, we compute whether there's a value that starts with it that would + // witness the usefulness of `v`. + let start_matrix = matrix; + let usefulnesses = split_ctors.into_iter().map(|ctor| { + // debug!("specialize({:?})", ctor); + // We cache the result of `Fields::wildcards` because it is used a lot. + let ctor_wild_subpatterns = Fields::wildcards(&pcx, &ctor); + let spec_matrix = + start_matrix.specialize_constructor(&pcx, &ctor, &ctor_wild_subpatterns); + let v = v.pop_head_constructor(&ctor_wild_subpatterns, cx); + let usefulness = + is_useful(cx, &spec_matrix, &v, witness_preference, is_under_guard, false); + usefulness.apply_constructor(&pcx, start_matrix, &ctor, &ctor_wild_subpatterns) + }); + Usefulness::merge(witness_preference, usefulnesses) + }; + + ret +} + +/// The arm of a match expression. +#[derive(Clone, Copy)] +pub(crate) struct MatchArm { + pub(crate) pat: PatId, + pub(crate) has_guard: bool, +} + +/// Indicates whether or not a given arm is reachable. +#[derive(Clone, Debug)] +pub(crate) enum Reachability { + /// The arm is reachable. This additionally carries a set of or-pattern branches that have been + /// found to be unreachable despite the overall arm being reachable. Used only in the presence + /// of or-patterns, otherwise it stays empty. + Reachable(Vec<()>), + /// The arm is unreachable. + Unreachable, +} +/// The output of checking a match for exhaustiveness and arm reachability. +pub(crate) struct UsefulnessReport { + /// For each arm of the input, whether that arm is reachable after the arms above it. + pub(crate) arm_usefulness: Vec<(MatchArm, Reachability)>, + /// If the match is exhaustive, this is empty. If not, this contains witnesses for the lack of + /// exhaustiveness. + pub(crate) non_exhaustiveness_witnesses: Vec, +} + +pub(crate) fn compute_match_usefulness( + cx: &MatchCheckCtx<'_>, + arms: &[MatchArm], +) -> UsefulnessReport { + let mut matrix = Matrix::empty(); + let arm_usefulness: Vec<_> = arms + .iter() + .copied() + .map(|arm| { + let v = PatStack::from_pattern(arm.pat); + let usefulness = is_useful(cx, &matrix, &v, LeaveOutWitness, arm.has_guard, true); + if !arm.has_guard { + matrix.push(v, cx); + } + let reachability = match usefulness { + NoWitnesses(subpats) if subpats.is_empty() => Reachability::Unreachable, + NoWitnesses(subpats) => { + Reachability::Reachable(subpats.list_unreachable_spans().unwrap()) + } + WithWitnesses(..) => panic!("bug"), + }; + (arm, reachability) + }) + .collect(); + + let wild_pattern = cx.pattern_arena.borrow_mut().alloc(Pat::Wild, &cx.infer[cx.match_expr]); + let v = PatStack::from_pattern(wild_pattern); + let usefulness = is_useful(cx, &matrix, &v, LeaveOutWitness, false, true); + let non_exhaustiveness_witnesses = match usefulness { + // TODO: ConstructWitness + // WithWitnesses(pats) => pats.into_iter().map(Witness::single_pattern).collect(), + // NoWitnesses(_) => panic!("bug"), + NoWitnesses(subpats) if subpats.is_empty() => Vec::new(), + NoWitnesses(subpats) => vec![Pat::Wild], + WithWitnesses(..) => panic!("bug"), + }; + UsefulnessReport { arm_usefulness, non_exhaustiveness_witnesses } +} + +pub(crate) struct PatternArena { + arena: Arena, + /// Types of expanded patterns. + type_of_epat: FxHashMap, +} + +impl PatternArena { + pub(crate) fn clone_from(pats: &Arena) -> RefCell { + PatternArena { arena: pats.clone(), type_of_epat: Default::default() }.into() + } + + fn alloc(&mut self, pat: Pat, ty: &Ty) -> PatId { + let id = self.arena.alloc(pat); + self.type_of_epat.insert(id, ty.clone()); + id + } +} + +impl Index for PatternArena { + type Output = Pat; + + fn index(&self, pat: PatId) -> &Pat { + &self.arena[pat] + } +} + +mod helper { + use hir_def::expr::{Pat, PatId}; + + use super::MatchCheckCtx; + + pub(super) trait PatIdExt: Sized { + fn is_wildcard(self, cx: &MatchCheckCtx<'_>) -> bool; + fn is_or_pat(self, cx: &MatchCheckCtx<'_>) -> bool; + fn expand_or_pat(self, cx: &MatchCheckCtx<'_>) -> Vec; + } + + // Copy-pasted from rust/compiler/rustc_data_structures/src/captures.rs + /// "Signaling" trait used in impl trait to tag lifetimes that you may + /// need to capture but don't really need for other reasons. + /// Basically a workaround; see [this comment] for details. + /// + /// [this comment]: https://github.com/rust-lang/rust/issues/34511#issuecomment-373423999 + // FIXME(eddyb) false positive, the lifetime parameter is "phantom" but needed. + #[allow(unused_lifetimes)] + pub trait Captures<'a> {} + + impl<'a, T: ?Sized> Captures<'a> for T {} +} + +#[test] +fn it_works() {} From 26baab5d2836eb5affd93d1991b3e96853f13869 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Wed, 28 Apr 2021 23:25:01 +0500 Subject: [PATCH 02/35] Enable generation of non-exhaustiveness witnesses --- crates/hir_ty/src/diagnostics/expr.rs | 3 +- .../diagnostics/pattern/deconstruct_pat.rs | 2 +- .../src/diagnostics/pattern/usefulness.rs | 84 ++++++++++++++++--- 3 files changed, 76 insertions(+), 13 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index ea70a5f9f62b..4d17e8c9a1b9 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -378,7 +378,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> { } else { &infer.type_of_expr[match_expr] }; - eprintln!("ExprValidator::validate_match2({:?})", match_expr_ty.kind(&Interner)); + // eprintln!("ExprValidator::validate_match2({:?})", match_expr_ty.kind(&Interner)); let pattern_arena = usefulness::PatternArena::clone_from(&body.pats); let cx = usefulness::MatchCheckCtx { @@ -408,6 +408,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> { // } let witnesses = report.non_exhaustiveness_witnesses; + eprintln!("compute_match_usefulness(..) -> {:?}", &witnesses); if !witnesses.is_empty() { if let Ok(source_ptr) = source_map.expr_syntax(id) { let root = source_ptr.file_syntax(db.upcast()); diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index cde04409e01d..2f35552055f7 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -109,6 +109,7 @@ impl Constructor { } } + /// Determines the constructor that the given pattern can be specialized to. pub(super) fn from_pat(cx: &MatchCheckCtx<'_>, pat: PatId) -> Self { match &cx.pattern_arena.borrow()[pat] { Pat::Bind { .. } | Pat::Wild => Wildcard, @@ -312,7 +313,6 @@ impl SplitWildcard { // // The exception is: if we are at the top-level, for example in an empty match, we // sometimes prefer reporting the list of constructors instead of just `_`. - let report_when_all_missing = pcx.is_top_level && !IntRange::is_integral(&pcx.ty); let ctor = if !self.matrix_ctors.is_empty() || report_when_all_missing { Missing diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index f5f6bf494953..89e6c6593288 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -179,6 +179,7 @@ impl FromIterator for PatStack { } } +/// A 2D matrix. #[derive(Clone)] pub(super) struct Matrix { patterns: Vec, @@ -321,6 +322,10 @@ impl SubPatSet { } _ => panic!("bug"), } + + if self.is_full() { + *self = Full; + } } /// Returns a list of the spans of the unreachable subpatterns. If `self` is empty (i.e. the @@ -449,14 +454,37 @@ impl Usefulness { ) -> Self { match self { WithWitnesses(witnesses) if witnesses.is_empty() => WithWitnesses(witnesses), - WithWitnesses(w) => { + WithWitnesses(witnesses) => { let new_witnesses = if matches!(ctor, Constructor::Missing) { let mut split_wildcard = SplitWildcard::new(pcx); split_wildcard.split(pcx, matrix.head_ctors(pcx.cx)); + // Construct for each missing constructor a "wild" version of this + // constructor, that matches everything that can be built with + // it. For example, if `ctor` is a `Constructor::Variant` for + // `Option::Some`, we get the pattern `Some(_)`. + let new_patterns: Vec<_> = split_wildcard + .iter_missing(pcx) + .map(|missing_ctor| { + Fields::wildcards(pcx, missing_ctor).apply(pcx, missing_ctor) + }) + .collect(); + witnesses + .into_iter() + .flat_map(|witness| { + new_patterns.iter().map(move |pat| { + let mut witness = witness.clone(); + witness.0.push(pat.clone()); + witness + }) + }) + .collect() } else { - todo!("Usefulness::apply_constructor({:?})", ctor) + witnesses + .into_iter() + .map(|witness| witness.apply_constructor(pcx, &ctor, ctor_wild_subpatterns)) + .collect() }; - todo!("Usefulness::apply_constructor({:?})", ctor) + WithWitnesses(new_witnesses) } NoWitnesses(subpats) => NoWitnesses(subpats.unspecialize(ctor_wild_subpatterns.len())), } @@ -469,6 +497,39 @@ enum WitnessPreference { LeaveOutWitness, } +/// A witness of non-exhaustiveness for error reporting, represented +/// as a list of patterns (in reverse order of construction) with +/// wildcards inside to represent elements that can take any inhabitant +/// of the type as a value. +/// +/// A witness against a list of patterns should have the same types +/// and length as the pattern matched against. Because Rust `match` +/// is always against a single pattern, at the end the witness will +/// have length 1, but in the middle of the algorithm, it can contain +/// multiple patterns. +/// +/// For example, if we are constructing a witness for the match against +/// +/// ``` +/// struct Pair(Option<(u32, u32)>, bool); +/// +/// match (p: Pair) { +/// Pair(None, _) => {} +/// Pair(_, false) => {} +/// } +/// ``` +/// +/// We'll perform the following steps: +/// 1. Start with an empty witness +/// `Witness(vec![])` +/// 2. Push a witness `true` against the `false` +/// `Witness(vec![true])` +/// 3. Push a witness `Some(_)` against the `None` +/// `Witness(vec![true, Some(_)])` +/// 4. Apply the `Pair` constructor to the witnesses +/// `Witness(vec![Pair(Some(_), true)])` +/// +/// The final `Pair(Some(_), true)` is then the resulting witness. #[derive(Clone, Debug)] pub(crate) struct Witness(Vec); @@ -560,7 +621,7 @@ fn is_useful( assert!(rows.iter().all(|r| r.len() == v.len())); // FIXME(Nadrieril): Hack to work around type normalization issues (see rust-lang/rust#72476). - // TODO(iDawer): ty.as_reference() + // TODO(iDawer): ty.strip_references() ? let ty = matrix.heads().next().map_or(cx.type_of(v.head()), |r| cx.type_of(r)); let pcx = PatCtxt { cx, ty, is_top_level }; @@ -643,6 +704,11 @@ pub(crate) struct UsefulnessReport { pub(crate) non_exhaustiveness_witnesses: Vec, } +/// The entrypoint for the usefulness algorithm. Computes whether a match is exhaustive and which +/// of its arms are reachable. +/// +/// Note: the input patterns must have been lowered through +/// `check_match::MatchVisitor::lower_pattern`. pub(crate) fn compute_match_usefulness( cx: &MatchCheckCtx<'_>, arms: &[MatchArm], @@ -670,14 +736,10 @@ pub(crate) fn compute_match_usefulness( let wild_pattern = cx.pattern_arena.borrow_mut().alloc(Pat::Wild, &cx.infer[cx.match_expr]); let v = PatStack::from_pattern(wild_pattern); - let usefulness = is_useful(cx, &matrix, &v, LeaveOutWitness, false, true); + let usefulness = is_useful(cx, &matrix, &v, ConstructWitness, false, true); let non_exhaustiveness_witnesses = match usefulness { - // TODO: ConstructWitness - // WithWitnesses(pats) => pats.into_iter().map(Witness::single_pattern).collect(), - // NoWitnesses(_) => panic!("bug"), - NoWitnesses(subpats) if subpats.is_empty() => Vec::new(), - NoWitnesses(subpats) => vec![Pat::Wild], - WithWitnesses(..) => panic!("bug"), + WithWitnesses(pats) => pats.into_iter().map(Witness::single_pattern).collect(), + NoWitnesses(_) => panic!("bug"), }; UsefulnessReport { arm_usefulness, non_exhaustiveness_witnesses } } From f4a95c93fe4c1050b18b3c8be25baddd6972ed84 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 29 Apr 2021 10:04:24 +0500 Subject: [PATCH 03/35] Remove unneeded indirection on PatCtxt --- crates/hir_ty/src/diagnostics/expr.rs | 4 ++-- .../diagnostics/pattern/deconstruct_pat.rs | 24 +++++++++---------- .../src/diagnostics/pattern/usefulness.rs | 20 ++++++++-------- 3 files changed, 24 insertions(+), 24 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index 4d17e8c9a1b9..88018b5d9a21 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -373,12 +373,12 @@ impl<'a, 'b> ExprValidator<'a, 'b> { let (body, source_map): (Arc, Arc) = db.body_with_source_map(self.owner); - let match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() { + let _match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() { return; } else { &infer.type_of_expr[match_expr] }; - // eprintln!("ExprValidator::validate_match2({:?})", match_expr_ty.kind(&Interner)); + // eprintln!("ExprValidator::validate_match2({:?})", _match_expr_ty.kind(&Interner)); let pattern_arena = usefulness::PatternArena::clone_from(&body.pats); let cx = usefulness::MatchCheckCtx { diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 2f35552055f7..d41b95d2f96c 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -143,7 +143,7 @@ impl Constructor { /// matrix, unless all of them are. pub(super) fn split<'a>( &self, - pcx: &PatCtxt<'_>, + pcx: PatCtxt<'_>, ctors: impl Iterator + Clone, ) -> SmallVec<[Self; 1]> { match self { @@ -166,7 +166,7 @@ impl Constructor { /// this checks for inclusion. // We inline because this has a single call site in `Matrix::specialize_constructor`. #[inline] - pub(super) fn is_covered_by(&self, pcx: &PatCtxt<'_>, other: &Self) -> bool { + pub(super) fn is_covered_by(&self, pcx: PatCtxt<'_>, other: &Self) -> bool { // This must be kept in sync with `is_covered_by_any`. match (self, other) { // Wildcards cover anything @@ -188,7 +188,7 @@ impl Constructor { /// Faster version of `is_covered_by` when applied to many constructors. `used_ctors` is /// assumed to be built from `matrix.head_ctors()` with wildcards filtered out, and `self` is /// assumed to have been split from a wildcard. - fn is_covered_by_any(&self, pcx: &PatCtxt<'_>, used_ctors: &[Constructor]) -> bool { + fn is_covered_by_any(&self, pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bool { if used_ctors.is_empty() { return false; } @@ -236,7 +236,7 @@ pub(super) struct SplitWildcard { } impl SplitWildcard { - pub(super) fn new(pcx: &PatCtxt<'_>) -> Self { + pub(super) fn new(pcx: PatCtxt<'_>) -> Self { // let cx = pcx.cx; // let make_range = |start, end| IntRange(todo!()); @@ -260,7 +260,7 @@ impl SplitWildcard { /// do what you want. pub(super) fn split<'a>( &mut self, - pcx: &PatCtxt<'_>, + pcx: PatCtxt<'_>, ctors: impl Iterator + Clone, ) { // Since `all_ctors` never contains wildcards, this won't recurse further. @@ -270,21 +270,21 @@ impl SplitWildcard { } /// Whether there are any value constructors for this type that are not present in the matrix. - fn any_missing(&self, pcx: &PatCtxt<'_>) -> bool { + fn any_missing(&self, pcx: PatCtxt<'_>) -> bool { self.iter_missing(pcx).next().is_some() } /// Iterate over the constructors for this type that are not present in the matrix. pub(super) fn iter_missing<'a>( &'a self, - pcx: &'a PatCtxt<'_>, + pcx: PatCtxt<'a>, ) -> impl Iterator { self.all_ctors.iter().filter(move |ctor| !ctor.is_covered_by_any(pcx, &self.matrix_ctors)) } /// Return the set of constructors resulting from splitting the wildcard. As explained at the /// top of the file, if any constructors are missing we can ignore the present ones. - fn into_ctors(self, pcx: &PatCtxt<'_>) -> SmallVec<[Constructor; 1]> { + fn into_ctors(self, pcx: PatCtxt<'_>) -> SmallVec<[Constructor; 1]> { if self.any_missing(pcx) { // Some constructors are missing, thus we can specialize with the special `Missing` // constructor, which stands for those constructors that are not seen in the matrix, @@ -313,7 +313,7 @@ impl SplitWildcard { // // The exception is: if we are at the top-level, for example in an empty match, we // sometimes prefer reporting the list of constructors instead of just `_`. - let report_when_all_missing = pcx.is_top_level && !IntRange::is_integral(&pcx.ty); + let report_when_all_missing = pcx.is_top_level && !IntRange::is_integral(pcx.ty); let ctor = if !self.matrix_ctors.is_empty() || report_when_all_missing { Missing } else { @@ -381,8 +381,8 @@ impl Fields { Fields::Vec(pats) } - pub(crate) fn wildcards(pcx: &PatCtxt<'_>, constructor: &Constructor) -> Self { - let ty = &pcx.ty; + pub(crate) fn wildcards(pcx: PatCtxt<'_>, constructor: &Constructor) -> Self { + let ty = pcx.ty; let cx = pcx.cx; let wildcard_from_ty = |ty| cx.alloc_pat(Pat::Wild, ty); @@ -446,7 +446,7 @@ impl Fields { /// `ty`: `Option` /// `self`: `[false]` /// returns `Some(false)` - pub(super) fn apply(self, pcx: &PatCtxt<'_>, ctor: &Constructor) -> Pat { + pub(super) fn apply(self, pcx: PatCtxt<'_>, ctor: &Constructor) -> Pat { let subpatterns_and_indices = self.patterns_and_indices(); let mut subpatterns = subpatterns_and_indices.iter().map(|&(_, p)| p); diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 89e6c6593288..7d9ab849b144 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -51,11 +51,11 @@ impl<'a> MatchCheckCtx<'a> { } } -#[derive(Clone)] +#[derive(Copy, Clone)] pub(super) struct PatCtxt<'a> { pub(super) cx: &'a MatchCheckCtx<'a>, /// Type of the current column under investigation. - pub(super) ty: Ty, + pub(super) ty: &'a Ty, /// Whether the current pattern is the whole pattern as found in a match arm, or if it's a /// subpattern. pub(super) is_top_level: bool, @@ -223,7 +223,7 @@ impl Matrix { /// This computes `S(constructor, self)`. See top of the file for explanations. fn specialize_constructor( &self, - pcx: &PatCtxt<'_>, + pcx: PatCtxt<'_>, ctor: &Constructor, ctor_wild_subpatterns: &Fields, ) -> Matrix { @@ -447,7 +447,7 @@ impl Usefulness { /// with the results of specializing with the other constructors. fn apply_constructor( self, - pcx: &PatCtxt<'_>, + pcx: PatCtxt<'_>, matrix: &Matrix, ctor: &Constructor, ctor_wild_subpatterns: &Fields, @@ -555,7 +555,7 @@ impl Witness { /// pats: [(false, "foo"), 42] => X { a: (false, "foo"), b: 42 } fn apply_constructor( mut self, - pcx: &PatCtxt<'_>, + pcx: PatCtxt<'_>, ctor: &Constructor, ctor_wild_subpatterns: &Fields, ) -> Self { @@ -623,7 +623,7 @@ fn is_useful( // FIXME(Nadrieril): Hack to work around type normalization issues (see rust-lang/rust#72476). // TODO(iDawer): ty.strip_references() ? let ty = matrix.heads().next().map_or(cx.type_of(v.head()), |r| cx.type_of(r)); - let pcx = PatCtxt { cx, ty, is_top_level }; + let pcx = PatCtxt { cx, ty: &ty, is_top_level }; // If the first pattern is an or-pattern, expand it. let ret = if v.head().is_or_pat(cx) { @@ -657,20 +657,20 @@ fn is_useful( // } // We split the head constructor of `v`. - let split_ctors = v_ctor.split(&pcx, matrix.head_ctors(cx)); + let split_ctors = v_ctor.split(pcx, matrix.head_ctors(cx)); // For each constructor, we compute whether there's a value that starts with it that would // witness the usefulness of `v`. let start_matrix = matrix; let usefulnesses = split_ctors.into_iter().map(|ctor| { // debug!("specialize({:?})", ctor); // We cache the result of `Fields::wildcards` because it is used a lot. - let ctor_wild_subpatterns = Fields::wildcards(&pcx, &ctor); + let ctor_wild_subpatterns = Fields::wildcards(pcx, &ctor); let spec_matrix = - start_matrix.specialize_constructor(&pcx, &ctor, &ctor_wild_subpatterns); + start_matrix.specialize_constructor(pcx, &ctor, &ctor_wild_subpatterns); let v = v.pop_head_constructor(&ctor_wild_subpatterns, cx); let usefulness = is_useful(cx, &spec_matrix, &v, witness_preference, is_under_guard, false); - usefulness.apply_constructor(&pcx, start_matrix, &ctor, &ctor_wild_subpatterns) + usefulness.apply_constructor(pcx, start_matrix, &ctor, &ctor_wild_subpatterns) }); Usefulness::merge(witness_preference, usefulnesses) }; From f4c396036416eaa977876d8ff4afe7f58f93c09e Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 29 Apr 2021 11:33:45 +0500 Subject: [PATCH 04/35] List useless patterns in a useful match arm --- .../src/diagnostics/pattern/usefulness.rs | 67 ++++++++++++++++--- 1 file changed, 58 insertions(+), 9 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 7d9ab849b144..57a416bec055 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -314,11 +314,28 @@ impl SubPatSet { } match (&mut *self, other) { - (Seq { .. }, Seq { .. }) => { - todo!() + (Seq { subpats: s_set }, Seq { subpats: mut o_set }) => { + s_set.retain(|i, s_sub_set| { + // Missing entries count as full. + let o_sub_set = o_set.remove(&i).unwrap_or(Full); + s_sub_set.union(o_sub_set); + // We drop full entries. + !s_sub_set.is_full() + }); + // Everything left in `o_set` is missing from `s_set`, i.e. counts as full. Since + // unioning with full returns full, we can drop those entries. } - (Alt { .. }, Alt { .. }) => { - todo!() + (Alt { subpats: s_set, .. }, Alt { subpats: mut o_set, .. }) => { + s_set.retain(|i, s_sub_set| { + // Missing entries count as empty. + let o_sub_set = o_set.remove(&i).unwrap_or(Empty); + s_sub_set.union(o_sub_set); + // We drop empty entries. + !s_sub_set.is_empty() + }); + // Everything left in `o_set` is missing from `s_set`, i.e. counts as empty. Since + // unioning with empty changes nothing, we can take those entries as is. + s_set.extend(o_set); } _ => panic!("bug"), } @@ -328,9 +345,38 @@ impl SubPatSet { } } - /// Returns a list of the spans of the unreachable subpatterns. If `self` is empty (i.e. the + /// Returns a list of the unreachable subpatterns. If `self` is empty (i.e. the /// whole pattern is unreachable) we return `None`. - fn list_unreachable_spans(&self) -> Option> { + fn list_unreachable_subpatterns(&self, cx: &MatchCheckCtx<'_>) -> Option> { + /// Panics if `set.is_empty()`. + fn fill_subpats( + set: &SubPatSet, + unreachable_pats: &mut Vec, + cx: &MatchCheckCtx<'_>, + ) { + match set { + SubPatSet::Empty => panic!("bug"), + SubPatSet::Full => {} + SubPatSet::Seq { subpats } => { + for (_, sub_set) in subpats { + fill_subpats(sub_set, unreachable_pats, cx); + } + } + SubPatSet::Alt { subpats, pat, alt_count, .. } => { + let expanded = pat.expand_or_pat(cx); + for i in 0..*alt_count { + let sub_set = subpats.get(&i).unwrap_or(&SubPatSet::Empty); + if sub_set.is_empty() { + // Found a unreachable subpattern. + unreachable_pats.push(expanded[i]); + } else { + fill_subpats(sub_set, unreachable_pats, cx); + } + } + } + } + } + if self.is_empty() { return None; } @@ -338,7 +384,9 @@ impl SubPatSet { // No subpatterns are unreachable. return Some(Vec::new()); } - todo!() + let mut unreachable_pats = Vec::new(); + fill_subpats(self, &mut unreachable_pats, cx); + Some(unreachable_pats) } /// When `self` refers to a patstack that was obtained from specialization, after running @@ -691,10 +739,11 @@ pub(crate) enum Reachability { /// The arm is reachable. This additionally carries a set of or-pattern branches that have been /// found to be unreachable despite the overall arm being reachable. Used only in the presence /// of or-patterns, otherwise it stays empty. - Reachable(Vec<()>), + Reachable(Vec), /// The arm is unreachable. Unreachable, } + /// The output of checking a match for exhaustiveness and arm reachability. pub(crate) struct UsefulnessReport { /// For each arm of the input, whether that arm is reachable after the arms above it. @@ -726,7 +775,7 @@ pub(crate) fn compute_match_usefulness( let reachability = match usefulness { NoWitnesses(subpats) if subpats.is_empty() => Reachability::Unreachable, NoWitnesses(subpats) => { - Reachability::Reachable(subpats.list_unreachable_spans().unwrap()) + Reachability::Reachable(subpats.list_unreachable_subpatterns(cx).unwrap()) } WithWitnesses(..) => panic!("bug"), }; From 2880fd23206042cc3564d388d2f991cb91e76c39 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 29 Apr 2021 12:08:52 +0500 Subject: [PATCH 05/35] Complete usefulness::SubPatSet impl --- .../src/diagnostics/pattern/usefulness.rs | 74 ++++++++++++++++++- 1 file changed, 71 insertions(+), 3 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 57a416bec055..2e5d2fb6c49f 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -1,5 +1,5 @@ // Based on rust-lang/rust 1.52.0-nightly (25c15cdbe 2021-04-22) -// rust/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs +// https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs use std::{cell::RefCell, iter::FromIterator, ops::Index, sync::Arc}; @@ -245,6 +245,33 @@ impl Matrix { } } +/// Given a pattern or a pattern-stack, this struct captures a set of its subpatterns. We use that +/// to track reachable sub-patterns arising from or-patterns. In the absence of or-patterns this +/// will always be either `Empty` (the whole pattern is unreachable) or `Full` (the whole pattern +/// is reachable). When there are or-patterns, some subpatterns may be reachable while others +/// aren't. In this case the whole pattern still counts as reachable, but we will lint the +/// unreachable subpatterns. +/// +/// This supports a limited set of operations, so not all possible sets of subpatterns can be +/// represented. That's ok, we only want the ones that make sense for our usage. +/// +/// What we're doing is illustrated by this: +/// ``` +/// match (true, 0) { +/// (true, 0) => {} +/// (_, 1) => {} +/// (true | false, 0 | 1) => {} +/// } +/// ``` +/// When we try the alternatives of the `true | false` or-pattern, the last `0` is reachable in the +/// `false` alternative but not the `true`. So overall it is reachable. By contrast, the last `1` +/// is not reachable in either alternative, so we want to signal this to the user. +/// Therefore we take the union of sets of reachable patterns coming from different alternatives in +/// order to figure out which subpatterns are overall reachable. +/// +/// Invariant: we try to construct the smallest representation we can. In particular if +/// `self.is_empty()` we ensure that `self` is `Empty`, and same with `Full`. This is not important +/// for correctness currently. #[derive(Debug, Clone)] enum SubPatSet { /// The empty set. This means the pattern is unreachable. @@ -397,7 +424,24 @@ impl SubPatSet { Full => Full, Empty => Empty, Seq { subpats } => { - todo!() + // We gather the first `arity` subpatterns together and shift the remaining ones. + let mut new_subpats = FxHashMap::default(); + let mut new_subpats_first_col = FxHashMap::default(); + for (i, sub_set) in subpats { + if i < arity { + // The first `arity` indices are now part of the pattern in the first + // column. + new_subpats_first_col.insert(i, sub_set); + } else { + // Indices after `arity` are simply shifted + new_subpats.insert(i - arity + 1, sub_set); + } + } + // If `new_subpats_first_col` has no entries it counts as full, so we can omit it. + if !new_subpats_first_col.is_empty() { + new_subpats.insert(0, Seq { subpats: new_subpats_first_col }); + } + Seq { subpats: new_subpats } } Alt { .. } => panic!("bug"), } @@ -417,7 +461,31 @@ impl SubPatSet { /// containing `false`. After `unsplit_or_pat`, we want the set to contain `None` and `false`. /// This is what this function does. fn unsplit_or_pat(mut self, alt_id: usize, alt_count: usize, pat: PatId) -> Self { - todo!() + use SubPatSet::*; + if self.is_empty() { + return Empty; + } + + // Subpatterns coming from inside the or-pattern alternative itself, e.g. in `None | Some(0 + // | 1)`. + let set_first_col = match &mut self { + Full => Full, + Seq { subpats } => subpats.remove(&0).unwrap_or(Full), + Empty => unreachable!(), + Alt { .. } => panic!("bug"), // `self` is a patstack + }; + let mut subpats_first_col = FxHashMap::default(); + subpats_first_col.insert(alt_id, set_first_col); + let set_first_col = Alt { subpats: subpats_first_col, pat, alt_count }; + + let mut subpats = match self { + Full => FxHashMap::default(), + Seq { subpats } => subpats, + Empty => unreachable!(), + Alt { .. } => panic!("bug"), // `self` is a patstack + }; + subpats.insert(0, set_first_col); + Seq { subpats } } } From 062c7953a12bf849db641d14d8d26af47ddca79e Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 29 Apr 2021 14:19:01 +0500 Subject: [PATCH 06/35] Add remaining Constructor variants --- .../diagnostics/pattern/deconstruct_pat.rs | 70 +++++++++++++++---- 1 file changed, 56 insertions(+), 14 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index d41b95d2f96c..c02e783af632 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -31,6 +31,10 @@ impl IntRange { } } + fn is_singleton(&self) -> bool { + todo!() + } + /// See `Constructor::is_covered_by` fn is_covered_by(&self, other: &Self) -> bool { todo!() @@ -66,8 +70,19 @@ pub(super) enum Constructor { Variant(EnumVariantId), /// Ranges of integer literal values (`2`, `2..=5` or `2..5`). IntRange(IntRange), + /// Ranges of floating-point literal values (`2.0..=5.2`). + FloatRange(ToDo), + /// String literals. Strings are not quite the same as `&[u8]` so we treat them separately. + Str(ToDo), /// Array and slice patterns. Slice(Slice), + /// Constants that must not be matched structurally. They are treated as black + /// boxes for the purposes of exhaustiveness: we must not inspect them, and they + /// don't count towards making a match exhaustive. + Opaque, + /// Fake extra constructor for enums that aren't allowed to be matched exhaustively. Also used + /// for those types for which we cannot list constructors explicitly, like `f64` and `str`. + NonExhaustive, /// Stands for constructors that are not seen in the matrix, as explained in the documentation /// for [`SplitWildcard`]. Missing, @@ -154,7 +169,9 @@ impl Constructor { } // Fast-track if the range is trivial. In particular, we don't do the overlapping // ranges check. - IntRange(_) => todo!("Constructor::split IntRange"), + IntRange(ctor_range) if !ctor_range.is_singleton() => { + todo!("Constructor::split IntRange") + } Slice(_) => todo!("Constructor::split Slice"), // Any other constructor can be used unchanged. _ => smallvec![self.clone()], @@ -177,11 +194,24 @@ impl Constructor { (Single, Single) => true, (Variant(self_id), Variant(other_id)) => self_id == other_id, - (Constructor::IntRange(_), Constructor::IntRange(_)) => todo!(), + (IntRange(self_range), IntRange(other_range)) => self_range.is_covered_by(other_range), + (FloatRange(..), FloatRange(..)) => { + todo!() + } + (Str(self_val), Str(other_val)) => { + todo!() + } + (Slice(self_slice), Slice(other_slice)) => self_slice.is_covered_by(*other_slice), - (Constructor::Slice(_), Constructor::Slice(_)) => todo!(), + // We are trying to inspect an opaque constant. Thus we skip the row. + (Opaque, _) | (_, Opaque) => false, + // Only a wildcard pattern can match the special extra constructor. + (NonExhaustive, _) => false, - _ => panic!("bug"), + _ => panic!( + "bug: trying to compare incompatible constructors {:?} and {:?}", + self, other + ), } } @@ -206,8 +236,11 @@ impl Constructor { .iter() .filter_map(|c| c.as_slice()) .any(|other| slice.is_covered_by(other)), - - _ => todo!(), + // This constructor is never covered by anything else + NonExhaustive => false, + Str(..) | FloatRange(..) | Opaque | Missing | Wildcard => { + panic!("bug: found unexpected ctor in all_ctors: {:?}", self) + } } } } @@ -425,8 +458,11 @@ impl Fields { } _ => panic!("Unexpected type for `Single` constructor: {:?}", ty), }, - Missing | Wildcard => Fields::Vec(Default::default()), - _ => todo!(), + Slice(slice) => { + todo!() + } + Str(..) | FloatRange(..) | IntRange(..) | NonExhaustive | Opaque | Missing + | Wildcard => Fields::Vec(Default::default()), }; ret } @@ -492,12 +528,18 @@ impl Fields { // TyKind::BoundVar(_) => {} // TyKind::InferenceVar(_, _) => {} }, - - _ => todo!(), - // Constructor::IntRange(_) => {} - // Constructor::Slice(_) => {} - // Missing => {} - // Wildcard => {} + Constructor::Slice(slice) => { + todo!() + } + Str(_) => todo!(), + FloatRange(..) => todo!(), + Constructor::IntRange(_) => todo!(), + NonExhaustive => Pat::Wild, + Wildcard => Pat::Wild, + Opaque => panic!("bug: we should not try to apply an opaque constructor"), + Missing => panic!( + "bug: trying to apply the `Missing` constructor; this should have been done in `apply_constructors`" + ), } } From 678d85ca7e4d7e631a450b8c050fe7696da0cac3 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 29 Apr 2021 23:28:43 +0500 Subject: [PATCH 07/35] Implement struct ctor application --- crates/hir_def/src/path.rs | 2 +- crates/hir_ty/src/diagnostics/expr.rs | 2 +- crates/hir_ty/src/diagnostics/pattern.rs | 55 +++++++- .../diagnostics/pattern/deconstruct_pat.rs | 123 ++++++++++-------- .../src/diagnostics/pattern/usefulness.rs | 8 +- 5 files changed, 121 insertions(+), 69 deletions(-) diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs index 16440041dcb5..4cdb5913deb5 100644 --- a/crates/hir_def/src/path.rs +++ b/crates/hir_def/src/path.rs @@ -166,7 +166,7 @@ impl Path { } /// Converts a known mod path to `Path`. - pub(crate) fn from_known_path( + pub fn from_known_path( path: ModPath, generic_args: Vec>>, ) -> Path { diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index 88018b5d9a21..a62f0fa4f637 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -382,7 +382,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> { let pattern_arena = usefulness::PatternArena::clone_from(&body.pats); let cx = usefulness::MatchCheckCtx { - krate: self.owner.module(db.upcast()).krate(), + module: self.owner.module(db.upcast()), match_expr, body, infer: &infer, diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 28c7a244d637..4dcbd7f9fedf 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -11,24 +11,67 @@ mod tests { use super::*; #[test] - fn unit_exhaustive() { + fn unit() { check_diagnostics( r#" fn main() { - match () { () => {} } - match () { _ => {} } + match () { () => {} } + match () { _ => {} } + match () { } + //^^ Missing match arm } "#, ); } #[test] - fn unit_non_exhaustive() { + fn tuple_of_units() { check_diagnostics( r#" fn main() { - match () { } - //^^ Missing match arm + match ((), ()) { ((), ()) => {} } + match ((), ()) { ((), _) => {} } + match ((), ()) { (_, _) => {} } + match ((), ()) { _ => {} } + match ((), ()) { } + //^^^^^^^^ Missing match arm +} +"#, + ); + } + + #[test] + fn tuple_with_ellipsis() { + // TODO: test non-exhaustive match with ellipsis in the middle + // of a pattern, check reported witness + check_diagnostics( + r#" +struct A; struct B; +fn main(v: (A, (), B)) { + match v { (A, ..) => {} } + match v { (.., B) => {} } + match v { (A, .., B) => {} } + match v { (..) => {} } + match v { } + //^ Missing match arm +} +"#, + ); + } + + #[test] + fn strukt() { + check_diagnostics( + r#" +struct A; struct B; +struct S { a: A, b: B} +fn main(v: S) { + match v { S { a, b } => {} } + match v { S { a: _, b: _ } => {} } + match v { S { .. } => {} } + match v { _ => {} } + match v { } + //^ Missing match arm } "#, ); diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index c02e783af632..7bd02a502091 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -1,5 +1,9 @@ use hir_def::{ - expr::{Pat, PatId}, + expr::{Pat, PatId, RecordFieldPat}, + find_path::find_path, + item_scope::ItemInNs, + path::Path, + type_ref::Mutability, AttrDefId, EnumVariantId, HasModule, VariantId, }; @@ -126,19 +130,25 @@ impl Constructor { /// Determines the constructor that the given pattern can be specialized to. pub(super) fn from_pat(cx: &MatchCheckCtx<'_>, pat: PatId) -> Self { + let ty = cx.type_of(pat); match &cx.pattern_arena.borrow()[pat] { Pat::Bind { .. } | Pat::Wild => Wildcard, Pat::Tuple { .. } | Pat::Ref { .. } | Pat::Box { .. } => Single, + Pat::Record { .. } | Pat::Path(_) | Pat::TupleStruct { .. } => { + let variant_id = + cx.infer.variant_resolution_for_pat(pat).unwrap_or_else(|| todo!()); + match variant_id { + VariantId::EnumVariantId(id) => Variant(id), + VariantId::StructId(_) | VariantId::UnionId(_) => Single, + } + } + Pat::Or(..) => panic!("bug: Or-pattern should have been expanded earlier on."), pat => todo!("Constructor::from_pat {:?}", pat), // Pat::Missing => {} - // Pat::Or(_) => {} - // Pat::Record { path, args, ellipsis } => {} // Pat::Range { start, end } => {} // Pat::Slice { prefix, slice, suffix } => {} - // Pat::Path(_) => {} // Pat::Lit(_) => {} - // Pat::TupleStruct { path, args, ellipsis } => {} // Pat::ConstBlock(_) => {} } } @@ -435,7 +445,8 @@ impl Fields { } else { let variant_id = constructor.variant_id_for_adt(*adt, cx); let variant = variant_id.variant_data(cx.db.upcast()); - let adt_is_local = variant_id.module(cx.db.upcast()).krate() == cx.krate; + let adt_is_local = + variant_id.module(cx.db.upcast()).krate() == cx.module.krate(); // Whether we must not match the fields of this variant exhaustively. let is_non_exhaustive = is_field_list_non_exhaustive(variant_id, cx) && !adt_is_local; @@ -490,43 +501,44 @@ impl Fields { Single | Variant(_) => match pcx.ty.kind(&Interner) { TyKind::Adt(..) | TyKind::Tuple(..) => { // We want the real indices here. - // TODO indices + // TODO indices and ellipsis interaction, tests let subpatterns = subpatterns_and_indices.iter().map(|&(_, pat)| pat).collect(); if let Some((adt, substs)) = pcx.ty.as_adt() { - if let hir_def::AdtId::EnumId(_) = adt { - todo!() - } else { - todo!() + let item = ItemInNs::Types(adt.into()); + let path = find_path(pcx.cx.db.upcast(), item, pcx.cx.module) + .map(|mpath| Path::from_known_path(mpath, Vec::new()).into()); + match adt { + hir_def::AdtId::EnumId(_) => todo!(), + hir_def::AdtId::StructId(id) => { + let variant_data = &pcx.cx.db.struct_data(id).variant_data; + let args = subpatterns_and_indices + .iter() + .zip(variant_data.fields().iter()) + .map(|(&(_, pat), (_, field_data))| RecordFieldPat { + name: field_data.name.clone(), + pat, + }) + .collect(); + Pat::Record { path, args, ellipsis: false } + } + hir_def::AdtId::UnionId(_) => todo!(), } } else { - // TODO ellipsis Pat::Tuple { args: subpatterns, ellipsis: None } } } - - _ => todo!(), - // TyKind::AssociatedType(_, _) => {} - // TyKind::Scalar(_) => {} - // TyKind::Array(_, _) => {} - // TyKind::Slice(_) => {} - // TyKind::Raw(_, _) => {} - // TyKind::Ref(_, _, _) => {} - // TyKind::OpaqueType(_, _) => {} - // TyKind::FnDef(_, _) => {} - // TyKind::Str => {} - // TyKind::Never => {} - // TyKind::Closure(_, _) => {} - // TyKind::Generator(_, _) => {} - // TyKind::GeneratorWitness(_, _) => {} - // TyKind::Foreign(_) => {} - // TyKind::Error => {} - // TyKind::Placeholder(_) => {} - // TyKind::Dyn(_) => {} - // TyKind::Alias(_) => {} - // TyKind::Function(_) => {} - // TyKind::BoundVar(_) => {} - // TyKind::InferenceVar(_, _) => {} + // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should + // be careful to reconstruct the correct constant pattern here. However a string + // literal pattern will never be reported as a non-exhaustiveness witness, so we + // can ignore this issue. + TyKind::Ref(..) => { + Pat::Ref { pat: subpatterns.next().unwrap(), mutability: Mutability::Shared } + } + TyKind::Slice(..) | TyKind::Array(..) => { + panic!("bug: bad slice pattern {:?} {:?}", ctor, pcx.ty) + } + _ => Pat::Wild, }, Constructor::Slice(slice) => { todo!() @@ -537,9 +549,9 @@ impl Fields { NonExhaustive => Pat::Wild, Wildcard => Pat::Wild, Opaque => panic!("bug: we should not try to apply an opaque constructor"), - Missing => panic!( - "bug: trying to apply the `Missing` constructor; this should have been done in `apply_constructors`" - ), + Missing => { + panic!("bug: trying to apply the `Missing` constructor; this should have been done in `apply_constructors`") + } } } @@ -628,30 +640,31 @@ impl Fields { cx: &MatchCheckCtx<'_>, ) -> Self { match &cx.pattern_arena.borrow()[pat] { - Pat::Ref { pat: subpattern, .. } => { + Pat::Ref { pat: subpattern, .. } | Pat::Box { inner: subpattern } => { assert_eq!(self.len(), 1); Fields::from_single_pattern(*subpattern) } - Pat::Tuple { args: subpatterns, ellipsis } => { + Pat::Tuple { args, ellipsis } | Pat::TupleStruct { args, ellipsis, .. } => { // FIXME(iDawer) handle ellipsis. // XXX(iDawer): in rustc, this is handled by HIR->TypedHIR lowering // rustc_mir_build::thir::pattern::PatCtxt::lower_tuple_subpats(..) - self.replace_with_fieldpats(subpatterns.iter().copied()) + self.replace_with_fieldpats(args.iter().copied()) } - - Pat::Wild => self.clone(), - pat => todo!("Fields::replace_with_pattern_arguments({:?})", pat), - // Pat::Missing => {} - // Pat::Or(_) => {} - // Pat::Record { path, args, ellipsis } => {} - // Pat::Range { start, end } => {} - // Pat::Slice { prefix, slice, suffix } => {} - // Pat::Path(_) => {} - // Pat::Lit(_) => {} - // Pat::Bind { mode, name, subpat } => {} - // Pat::TupleStruct { path, args, ellipsis } => {} - // Pat::Box { inner } => {} - // Pat::ConstBlock(_) => {} + Pat::Record { args, ellipsis, .. } => { + // FIXME(iDawer) handle ellipsis. + self.replace_with_fieldpats(args.iter().map(|field_pat| field_pat.pat)) + } + Pat::Slice { .. } => { + todo!() + } + Pat::Missing + | Pat::Wild + | Pat::Or(_) + | Pat::Range { .. } + | Pat::Path(_) + | Pat::Lit(_) + | Pat::Bind { .. } + | Pat::ConstBlock(_) => self.clone(), } } } diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 2e5d2fb6c49f..4b55aee97dbe 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -3,11 +3,7 @@ use std::{cell::RefCell, iter::FromIterator, ops::Index, sync::Arc}; -use base_db::CrateId; -use hir_def::{ - body::Body, - expr::{ExprId, Pat, PatId}, -}; +use hir_def::{ModuleId, body::Body, expr::{ExprId, Pat, PatId}}; use la_arena::Arena; use once_cell::unsync::OnceCell; use rustc_hash::FxHashMap; @@ -24,7 +20,7 @@ use self::{ }; pub(crate) struct MatchCheckCtx<'a> { - pub(crate) krate: CrateId, + pub(crate) module: ModuleId, pub(crate) match_expr: ExprId, pub(crate) body: Arc, pub(crate) infer: &'a InferenceResult, From b4f41973326a684844ffe23c5816e17d485b4203 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Fri, 30 Apr 2021 13:33:07 +0500 Subject: [PATCH 08/35] Build wildcard witnesses instead of panicking --- .../src/diagnostics/pattern/deconstruct_pat.rs | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 7bd02a502091..60323aea3b48 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -496,6 +496,8 @@ impl Fields { pub(super) fn apply(self, pcx: PatCtxt<'_>, ctor: &Constructor) -> Pat { let subpatterns_and_indices = self.patterns_and_indices(); let mut subpatterns = subpatterns_and_indices.iter().map(|&(_, p)| p); + // TODO witnesses are not yet used + const TODO: Pat = Pat::Wild; match ctor { Single | Variant(_) => match pcx.ty.kind(&Interner) { @@ -509,7 +511,7 @@ impl Fields { let path = find_path(pcx.cx.db.upcast(), item, pcx.cx.module) .map(|mpath| Path::from_known_path(mpath, Vec::new()).into()); match adt { - hir_def::AdtId::EnumId(_) => todo!(), + hir_def::AdtId::EnumId(id) => TODO, hir_def::AdtId::StructId(id) => { let variant_data = &pcx.cx.db.struct_data(id).variant_data; let args = subpatterns_and_indices @@ -522,7 +524,7 @@ impl Fields { .collect(); Pat::Record { path, args, ellipsis: false } } - hir_def::AdtId::UnionId(_) => todo!(), + hir_def::AdtId::UnionId(_) => Pat::Wild, } } else { Pat::Tuple { args: subpatterns, ellipsis: None } @@ -540,12 +542,10 @@ impl Fields { } _ => Pat::Wild, }, - Constructor::Slice(slice) => { - todo!() - } - Str(_) => todo!(), - FloatRange(..) => todo!(), - Constructor::IntRange(_) => todo!(), + Constructor::Slice(slice) => TODO, + Str(_) => TODO, + FloatRange(..) => TODO, + Constructor::IntRange(_) => TODO, NonExhaustive => Pat::Wild, Wildcard => Pat::Wild, Opaque => panic!("bug: we should not try to apply an opaque constructor"), From 5a8a0b62697c01ef881e7e2a0387e3649cab2034 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Fri, 30 Apr 2021 19:12:04 +0500 Subject: [PATCH 09/35] Check enum patterns --- crates/hir_ty/src/diagnostics/pattern.rs | 45 +++++++++++++ .../diagnostics/pattern/deconstruct_pat.rs | 64 +++++++++++++++++-- .../src/diagnostics/pattern/usefulness.rs | 21 +++++- 3 files changed, 124 insertions(+), 6 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 4dcbd7f9fedf..3e90461ccd38 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -73,6 +73,51 @@ fn main(v: S) { match v { } //^ Missing match arm } +"#, + ); + } + + #[test] + fn c_enum() { + check_diagnostics( + r#" +enum E { A, B } +fn main(v: E) { + match v { E::A | E::B => {} } + match v { _ => {} } + match v { E::A => {} } + //^ Missing match arm + match v { } + //^ Missing match arm +} +"#, + ); + } + + #[test] + fn enum_() { + check_diagnostics( + r#" +struct A; struct B; +enum E { Tuple(A, B), Struct{ a: A, b: B } } +fn main(v: E) { + match v { + E::Tuple(a, b) => {} + E::Struct{ a, b } => {} + } + match v { + E::Tuple(_, _) => {} + E::Struct{..} => {} + } + match v { + E::Tuple(..) => {} + _ => {} + } + match v { E::Tuple(..) => {} } + //^ Missing match arm + match v { } + //^ Missing match arm +} "#, ); } diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 60323aea3b48..3c1811f95ec7 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -135,6 +135,7 @@ impl Constructor { Pat::Bind { .. } | Pat::Wild => Wildcard, Pat::Tuple { .. } | Pat::Ref { .. } | Pat::Box { .. } => Single, Pat::Record { .. } | Pat::Path(_) | Pat::TupleStruct { .. } => { + // TODO: path to const let variant_id = cx.infer.variant_resolution_for_pat(pat).unwrap_or_else(|| todo!()); match variant_id { @@ -144,8 +145,8 @@ impl Constructor { } Pat::Or(..) => panic!("bug: Or-pattern should have been expanded earlier on."), + Pat::Missing => todo!("Fail gracefully when there is an error in a pattern"), pat => todo!("Constructor::from_pat {:?}", pat), - // Pat::Missing => {} // Pat::Range { start, end } => {} // Pat::Slice { prefix, slice, suffix } => {} // Pat::Lit(_) => {} @@ -280,7 +281,7 @@ pub(super) struct SplitWildcard { impl SplitWildcard { pub(super) fn new(pcx: PatCtxt<'_>) -> Self { - // let cx = pcx.cx; + let cx = pcx.cx; // let make_range = |start, end| IntRange(todo!()); // This determines the set of all possible constructors for the type `pcx.ty`. For numbers, @@ -292,9 +293,62 @@ impl SplitWildcard { // Invariant: this is empty if and only if the type is uninhabited (as determined by // `cx.is_uninhabited()`). let all_ctors = match pcx.ty.kind(&Interner) { - TyKind::Adt(AdtId(hir_def::AdtId::EnumId(_)), _) => todo!(), + TyKind::Scalar(Scalar::Bool) => todo!(), + // TyKind::Array(..) if ... => todo!(), + TyKind::Array(..) | TyKind::Slice(..) => todo!(), + &TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref _substs) => { + let enum_data = cx.db.enum_data(enum_id); + + // If the enum is declared as `#[non_exhaustive]`, we treat it as if it had an + // additional "unknown" constructor. + // There is no point in enumerating all possible variants, because the user can't + // actually match against them all themselves. So we always return only the fictitious + // constructor. + // E.g., in an example like: + // + // ``` + // let err: io::ErrorKind = ...; + // match err { + // io::ErrorKind::NotFound => {}, + // } + // ``` + // + // we don't want to show every possible IO error, but instead have only `_` as the + // witness. + let is_declared_nonexhaustive = cx.is_foreign_non_exhaustive_enum(enum_id); + + // If `exhaustive_patterns` is disabled and our scrutinee is an empty enum, we treat it + // as though it had an "unknown" constructor to avoid exposing its emptiness. The + // exception is if the pattern is at the top level, because we want empty matches to be + // considered exhaustive. + let is_secretly_empty = enum_data.variants.is_empty() + && !cx.feature_exhaustive_patterns() + && !pcx.is_top_level; + + if is_secretly_empty || is_declared_nonexhaustive { + smallvec![NonExhaustive] + } else if cx.feature_exhaustive_patterns() { + // If `exhaustive_patterns` is enabled, we exclude variants known to be + // uninhabited. + todo!() + } else { + enum_data + .variants + .iter() + .map(|(local_id, ..)| Variant(EnumVariantId { parent: enum_id, local_id })) + .collect() + } + } + TyKind::Scalar(Scalar::Char) => todo!(), + TyKind::Scalar(Scalar::Int(..)) | TyKind::Scalar(Scalar::Uint(..)) => todo!(), + TyKind::Never if !cx.feature_exhaustive_patterns() && !pcx.is_top_level => { + smallvec![NonExhaustive] + } + TyKind::Never => SmallVec::new(), + _ if cx.is_uninhabited(&pcx.ty) => SmallVec::new(), TyKind::Adt(..) | TyKind::Tuple(..) | TyKind::Ref(..) => smallvec![Single], - _ => todo!(), + // This type is one for which we cannot list constructors, like `str` or `f64`. + _ => smallvec![NonExhaustive], }; SplitWildcard { matrix_ctors: Vec::new(), all_ctors } } @@ -496,7 +550,7 @@ impl Fields { pub(super) fn apply(self, pcx: PatCtxt<'_>, ctor: &Constructor) -> Pat { let subpatterns_and_indices = self.patterns_and_indices(); let mut subpatterns = subpatterns_and_indices.iter().map(|&(_, p)| p); - // TODO witnesses are not yet used + // TODO witnesses are not yet used const TODO: Pat = Pat::Wild; match ctor { diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 4b55aee97dbe..2df87ccea146 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -3,7 +3,11 @@ use std::{cell::RefCell, iter::FromIterator, ops::Index, sync::Arc}; -use hir_def::{ModuleId, body::Body, expr::{ExprId, Pat, PatId}}; +use hir_def::{ + body::Body, + expr::{ExprId, Pat, PatId}, + HasModule, ModuleId, +}; use la_arena::Arena; use once_cell::unsync::OnceCell; use rustc_hash::FxHashMap; @@ -36,6 +40,21 @@ impl<'a> MatchCheckCtx<'a> { false } + /// Returns whether the given type is an enum from another crate declared `#[non_exhaustive]`. + pub(super) fn is_foreign_non_exhaustive_enum(&self, enum_id: hir_def::EnumId) -> bool { + let has_non_exhaustive_attr = + self.db.attrs(enum_id.into()).by_key("non_exhaustive").exists(); + let is_local = + hir_def::AdtId::from(enum_id).module(self.db.upcast()).krate() == self.module.krate(); + has_non_exhaustive_attr && !is_local + } + + // Rust feature described as "Allows exhaustive pattern matching on types that contain uninhabited types." + pub(super) fn feature_exhaustive_patterns(&self) -> bool { + // TODO + false + } + pub(super) fn alloc_pat(&self, pat: Pat, ty: &Ty) -> PatId { self.pattern_arena.borrow_mut().alloc(pat, ty) } From 3a85e47f6ab586328ee17bb27e8dae3e3e247e23 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Sun, 2 May 2021 20:09:31 +0500 Subject: [PATCH 10/35] Support bool literal patterns --- crates/hir_ty/src/diagnostics/pattern.rs | 26 +++ .../diagnostics/pattern/deconstruct_pat.rs | 165 +++++++++++++++++- 2 files changed, 182 insertions(+), 9 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 3e90461ccd38..044506d66989 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -118,6 +118,32 @@ fn main(v: E) { match v { } //^ Missing match arm } +"#, + ); + } + + #[test] + fn boolean() { + check_diagnostics( + r#" +fn main() { + match true { + true => {} + false => {} + } + match true { + true | false => {} + } + match true { + true => {} + _ => {} + } + match true {} + //^^^^ Missing match arm + match true { true => {} } + //^^^^ Missing match arm + +} "#, ); } diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 3c1811f95ec7..393d9999716e 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -1,12 +1,17 @@ +use std::{ + cmp::{max, min}, + iter::once, + ops::RangeInclusive, +}; + use hir_def::{ - expr::{Pat, PatId, RecordFieldPat}, + expr::{Expr, Literal, Pat, PatId, RecordFieldPat}, find_path::find_path, item_scope::ItemInNs, path::Path, type_ref::Mutability, AttrDefId, EnumVariantId, HasModule, VariantId, }; - use smallvec::{smallvec, SmallVec}; use crate::{AdtId, Interner, Scalar, Ty, TyExt, TyKind}; @@ -20,7 +25,7 @@ pub(super) enum ToDo {} #[derive(Clone, Debug, PartialEq, Eq)] pub(super) struct IntRange { - range: ToDo, + range: RangeInclusive, } impl IntRange { @@ -36,12 +41,147 @@ impl IntRange { } fn is_singleton(&self) -> bool { - todo!() + self.range.start() == self.range.end() + } + + fn boundaries(&self) -> (u128, u128) { + (*self.range.start(), *self.range.end()) + } + + #[inline] + fn from_bool(value: bool) -> IntRange { + let val = value as u128; + IntRange { range: val..=val } + } + + #[inline] + fn from_range(cx: &MatchCheckCtx<'_>, lo: u128, hi: u128, scalar_ty: Scalar) -> IntRange { + if let Scalar::Bool = scalar_ty { + IntRange { range: lo..=hi } + } else { + todo!() + } + } + + fn is_subrange(&self, other: &Self) -> bool { + other.range.start() <= self.range.start() && self.range.end() <= other.range.end() + } + + fn intersection(&self, other: &Self) -> Option { + let (lo, hi) = self.boundaries(); + let (other_lo, other_hi) = other.boundaries(); + if lo <= other_hi && other_lo <= hi { + Some(IntRange { range: max(lo, other_lo)..=min(hi, other_hi) }) + } else { + None + } } /// See `Constructor::is_covered_by` fn is_covered_by(&self, other: &Self) -> bool { - todo!() + if self.intersection(other).is_some() { + // Constructor splitting should ensure that all intersections we encounter are actually + // inclusions. + assert!(self.is_subrange(other)); + true + } else { + false + } + } +} + +/// Represents a border between 2 integers. Because the intervals spanning borders must be able to +/// cover every integer, we need to be able to represent 2^128 + 1 such borders. +#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)] +enum IntBorder { + JustBefore(u128), + AfterMax, +} + +/// A range of integers that is partitioned into disjoint subranges. This does constructor +/// splitting for integer ranges as explained at the top of the file. +/// +/// This is fed multiple ranges, and returns an output that covers the input, but is split so that +/// the only intersections between an output range and a seen range are inclusions. No output range +/// straddles the boundary of one of the inputs. +/// +/// The following input: +/// ``` +/// |-------------------------| // `self` +/// |------| |----------| |----| +/// |-------| |-------| +/// ``` +/// would be iterated over as follows: +/// ``` +/// ||---|--||-|---|---|---|--| +/// ``` +#[derive(Debug, Clone)] +struct SplitIntRange { + /// The range we are splitting + range: IntRange, + /// The borders of ranges we have seen. They are all contained within `range`. This is kept + /// sorted. + borders: Vec, +} + +impl SplitIntRange { + fn new(range: IntRange) -> Self { + SplitIntRange { range, borders: Vec::new() } + } + + /// Internal use + fn to_borders(r: IntRange) -> [IntBorder; 2] { + use IntBorder::*; + let (lo, hi) = r.boundaries(); + let lo = JustBefore(lo); + let hi = match hi.checked_add(1) { + Some(m) => JustBefore(m), + None => AfterMax, + }; + [lo, hi] + } + + /// Add ranges relative to which we split. + fn split(&mut self, ranges: impl Iterator) { + let this_range = &self.range; + let included_ranges = ranges.filter_map(|r| this_range.intersection(&r)); + let included_borders = included_ranges.flat_map(|r| { + let borders = Self::to_borders(r); + once(borders[0]).chain(once(borders[1])) + }); + self.borders.extend(included_borders); + self.borders.sort_unstable(); + } + + /// Iterate over the contained ranges. + fn iter(&self) -> impl Iterator + '_ { + use IntBorder::*; + + let self_range = Self::to_borders(self.range.clone()); + // Start with the start of the range. + let mut prev_border = self_range[0]; + self.borders + .iter() + .copied() + // End with the end of the range. + .chain(once(self_range[1])) + // List pairs of adjacent borders. + .map(move |border| { + let ret = (prev_border, border); + prev_border = border; + ret + }) + // Skip duplicates. + .filter(|(prev_border, border)| prev_border != border) + // Finally, convert to ranges. + .map(|(prev_border, border)| { + let range = match (prev_border, border) { + (JustBefore(n), JustBefore(m)) if n < m => n..=(m - 1), + (JustBefore(n), AfterMax) => n..=u128::MAX, + _ => unreachable!(), // Ruled out by the sorting and filtering we did + }; + IntRange { range } + }) } } @@ -143,13 +283,16 @@ impl Constructor { VariantId::StructId(_) | VariantId::UnionId(_) => Single, } } + &Pat::Lit(expr_id) => match cx.body[expr_id] { + Expr::Literal(Literal::Bool(val)) => IntRange(IntRange::from_bool(val)), + _ => todo!(), + }, Pat::Or(..) => panic!("bug: Or-pattern should have been expanded earlier on."), Pat::Missing => todo!("Fail gracefully when there is an error in a pattern"), pat => todo!("Constructor::from_pat {:?}", pat), // Pat::Range { start, end } => {} // Pat::Slice { prefix, slice, suffix } => {} - // Pat::Lit(_) => {} // Pat::ConstBlock(_) => {} } } @@ -181,7 +324,10 @@ impl Constructor { // Fast-track if the range is trivial. In particular, we don't do the overlapping // ranges check. IntRange(ctor_range) if !ctor_range.is_singleton() => { - todo!("Constructor::split IntRange") + let mut split_range = SplitIntRange::new(ctor_range.clone()); + let int_ranges = ctors.filter_map(|ctor| ctor.as_int_range()); + split_range.split(int_ranges.cloned()); + split_range.iter().map(IntRange).collect() } Slice(_) => todo!("Constructor::split Slice"), // Any other constructor can be used unchanged. @@ -282,7 +428,8 @@ pub(super) struct SplitWildcard { impl SplitWildcard { pub(super) fn new(pcx: PatCtxt<'_>) -> Self { let cx = pcx.cx; - // let make_range = |start, end| IntRange(todo!()); + let make_range = + |start, end, scalar| IntRange(IntRange::from_range(cx, start, end, scalar)); // This determines the set of all possible constructors for the type `pcx.ty`. For numbers, // arrays and slices we use ranges and variable-length slices when appropriate. @@ -293,7 +440,7 @@ impl SplitWildcard { // Invariant: this is empty if and only if the type is uninhabited (as determined by // `cx.is_uninhabited()`). let all_ctors = match pcx.ty.kind(&Interner) { - TyKind::Scalar(Scalar::Bool) => todo!(), + TyKind::Scalar(Scalar::Bool) => smallvec![make_range(0, 1, Scalar::Bool)], // TyKind::Array(..) if ... => todo!(), TyKind::Array(..) | TyKind::Slice(..) => todo!(), &TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref _substs) => { From 3ffcb2658cc2199271d3a22f9747517d8e2892d6 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Sun, 2 May 2021 20:56:54 +0500 Subject: [PATCH 11/35] Complete field replacing --- crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 393d9999716e..d3513c40629a 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -811,8 +811,13 @@ impl Fields { pats: impl IntoIterator, ) -> Self { let pats = { - let mut arena = cx.pattern_arena.borrow_mut(); - pats.into_iter().map(move |pat| /* arena.alloc(pat) */ todo!()).collect() + let tys: SmallVec<[Ty; 2]> = match self { + Fields::Vec(pats) => pats.iter().copied().map(|pat| cx.type_of(pat)).collect(), + }; + pats.into_iter() + .zip(tys.into_iter()) + .map(move |(pat, ty)| cx.alloc_pat(pat, &ty)) + .collect() }; match self { From 2431ff5987ee1f802ede0db5eedc863ce9a8e70f Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Mon, 3 May 2021 00:09:21 +0500 Subject: [PATCH 12/35] Handle unordered fields in struct patterns --- .../src/diagnostics/pattern/deconstruct_pat.rs | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index d3513c40629a..248a379b3516 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -857,8 +857,18 @@ impl Fields { self.replace_with_fieldpats(args.iter().copied()) } Pat::Record { args, ellipsis, .. } => { - // FIXME(iDawer) handle ellipsis. - self.replace_with_fieldpats(args.iter().map(|field_pat| field_pat.pat)) + let variant_id = + cx.infer.variant_resolution_for_pat(pat).unwrap_or_else(|| todo!()); + let variant_data = variant_id.variant_data(cx.db.upcast()); + + let new_pats = args.iter().map(|field_pat| { + // TODO: field lookup is inefficient + let raw = + variant_data.field(&field_pat.name).unwrap_or_else(|| todo!()).into_raw(); + let idx = u32::from(raw) as usize; + (idx, field_pat.pat) + }); + self.replace_fields_indexed(new_pats) } Pat::Slice { .. } => { todo!() From 975109051caf05de6d166779589e299d9aca9cd5 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 6 May 2021 09:42:00 +0500 Subject: [PATCH 13/35] Basic lowering hir_def::exrp::Pat -> typed HIR. Pattern arena is broken --- crates/hir_ty/src/diagnostics/expr.rs | 39 +++- crates/hir_ty/src/diagnostics/pattern.rs | 191 ++++++++++++++++++ .../diagnostics/pattern/deconstruct_pat.rs | 186 ++++++++--------- .../src/diagnostics/pattern/pat_util.rs | 52 +++++ .../src/diagnostics/pattern/usefulness.rs | 83 ++++---- 5 files changed, 387 insertions(+), 164 deletions(-) create mode 100644 crates/hir_ty/src/diagnostics/pattern/pat_util.rs diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index a62f0fa4f637..8f141a308d2f 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -2,7 +2,7 @@ //! through the body using inference results: mismatched arg counts, missing //! fields, etc. -use std::sync::Arc; +use std::{cell::RefCell, sync::Arc}; use hir_def::{expr::Statement, path::path, resolver::HasResolver, AssocItemId, DefWithBodyId}; use hir_expand::name; @@ -26,7 +26,13 @@ pub(crate) use hir_def::{ LocalFieldId, VariantId, }; -use super::ReplaceFilterMapNextWithFindMap; +use super::{ + pattern::{ + self, + usefulness::{expand_pattern, PatternArena}, + }, + ReplaceFilterMapNextWithFindMap, +}; pub(super) struct ExprValidator<'a, 'b: 'a> { owner: DefWithBodyId, @@ -380,7 +386,16 @@ impl<'a, 'b> ExprValidator<'a, 'b> { }; // eprintln!("ExprValidator::validate_match2({:?})", _match_expr_ty.kind(&Interner)); - let pattern_arena = usefulness::PatternArena::clone_from(&body.pats); + let pattern_arena = RefCell::new(PatternArena::new()); + + let m_arms: Vec<_> = arms + .iter() + .map(|arm| usefulness::MatchArm { + pat: self.lower_pattern(arm.pat, &mut pattern_arena.borrow_mut(), db, &body), + has_guard: arm.guard.is_some(), + }) + .collect(); + let cx = usefulness::MatchCheckCtx { module: self.owner.module(db.upcast()), match_expr, @@ -389,12 +404,6 @@ impl<'a, 'b> ExprValidator<'a, 'b> { db, pattern_arena: &pattern_arena, }; - - let m_arms: Vec<_> = arms - .iter() - .map(|arm| usefulness::MatchArm { pat: arm.pat, has_guard: arm.guard.is_some() }) - .collect(); - let report = usefulness::compute_match_usefulness(&cx, &m_arms); // TODO Report unreacheble arms @@ -427,6 +436,18 @@ impl<'a, 'b> ExprValidator<'a, 'b> { } } + fn lower_pattern( + &self, + pat: PatId, + pattern_arena: &mut PatternArena, + db: &dyn HirDatabase, + body: &Body, + ) -> pattern::PatId { + let mut patcx = pattern::PatCtxt::new(db, &self.infer, body); + let pattern = patcx.lower_pattern(pat); + pattern_arena.alloc(expand_pattern(pattern)) + } + fn validate_results_in_tail_expr(&mut self, body_id: ExprId, id: ExprId, db: &dyn HirDatabase) { // the mismatch will be on the whole block currently let mismatch = match self.infer.type_mismatch_for_expr(body_id) { diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 044506d66989..6646826b3303 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -2,8 +2,199 @@ #![allow(unused)] // todo remove mod deconstruct_pat; +// TODO: find a better place for this? +mod pat_util; pub mod usefulness; +use hir_def::{body::Body, EnumVariantId, LocalFieldId, VariantId}; +use la_arena::Idx; + +use crate::{db::HirDatabase, AdtId, InferenceResult, Interner, Substitution, Ty, TyKind}; + +use self::{deconstruct_pat::ToDo, pat_util::EnumerateAndAdjustIterator}; + +pub type PatId = Idx; + +#[derive(Clone, Debug)] +pub(crate) enum PatternError { + Unimplemented, +} + +#[derive(Clone, Debug, PartialEq)] +pub struct FieldPat { + pub field: LocalFieldId, + pub pattern: Pat, +} + +#[derive(Clone, Debug, PartialEq)] +pub struct Pat { + pub ty: Ty, + pub kind: Box, +} + +impl Pat { + pub(crate) fn wildcard_from_ty(ty: &Ty) -> Self { + Pat { ty: ty.clone(), kind: Box::new(PatKind::Wild) } + } +} + +#[derive(Clone, Debug, PartialEq)] +pub enum PatKind { + Wild, + + /// `x`, `ref x`, `x @ P`, etc. + Binding { + subpattern: Option, + // todo: ToDo, + }, + + /// `Foo(...)` or `Foo{...}` or `Foo`, where `Foo` is a variant name from an ADT with + /// multiple variants. + Variant { + substs: Substitution, + enum_variant: EnumVariantId, + subpatterns: Vec, + }, + + /// `(...)`, `Foo(...)`, `Foo{...}`, or `Foo`, where `Foo` is a variant name from an ADT with + /// a single variant. + Leaf { + subpatterns: Vec, + }, + + /// `box P`, `&P`, `&mut P`, etc. + Deref { + subpattern: Pat, + }, + + /// An or-pattern, e.g. `p | q`. + /// Invariant: `pats.len() >= 2`. + Or { + pats: Vec, + }, +} + +pub(crate) struct PatCtxt<'a> { + db: &'a dyn HirDatabase, + infer: &'a InferenceResult, + body: &'a Body, + pub(crate) errors: Vec, +} + +impl<'a> PatCtxt<'a> { + pub(crate) fn new(db: &'a dyn HirDatabase, infer: &'a InferenceResult, body: &'a Body) -> Self { + Self { db, infer, body, errors: Vec::new() } + } + + pub(crate) fn lower_pattern(&mut self, pat: hir_def::expr::PatId) -> Pat { + // TODO: pattern adjustments (implicit dereference) + // More info https://github.com/rust-lang/rust/issues/42640#issuecomment-313535089 + let unadjusted_pat = self.lower_pattern_unadjusted(pat); + unadjusted_pat + } + + fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat { + let ty = &self.infer[pat]; + + let kind = match self.body[pat] { + hir_def::expr::Pat::Wild => PatKind::Wild, + + hir_def::expr::Pat::Tuple { ref args, ellipsis } => { + let arity = match *ty.kind(&Interner) { + TyKind::Tuple(arity, _) => arity, + _ => panic!("unexpected type for tuple pattern: {:?}", ty), + }; + let subpatterns = self.lower_tuple_subpats(args, arity, ellipsis); + PatKind::Leaf { subpatterns } + } + + hir_def::expr::Pat::TupleStruct { ref args, ellipsis, .. } => { + let variant_data = match self.infer.variant_resolution_for_pat(pat) { + Some(variant_id) => variant_id.variant_data(self.db.upcast()), + None => panic!("tuple struct pattern not applied to an ADT {:?}", ty), + }; + let subpatterns = + self.lower_tuple_subpats(args, variant_data.fields().len(), ellipsis); + self.lower_variant_or_leaf(pat, ty, subpatterns) + } + + hir_def::expr::Pat::Record { ref args, .. } => { + let variant_data = match self.infer.variant_resolution_for_pat(pat) { + Some(variant_id) => variant_id.variant_data(self.db.upcast()), + None => panic!("record pattern not applied to an ADT {:?}", ty), + }; + let subpatterns = args + .iter() + .map(|field| FieldPat { + // XXX(iDawer): field lookup is inefficient + field: variant_data.field(&field.name).unwrap_or_else(|| todo!()), + pattern: self.lower_pattern(field.pat), + }) + .collect(); + self.lower_variant_or_leaf(pat, ty, subpatterns) + } + + hir_def::expr::Pat::Or(ref pats) => PatKind::Or { pats: self.lower_patterns(pats) }, + + _ => { + self.errors.push(PatternError::Unimplemented); + PatKind::Wild + } + }; + + Pat { ty: ty.clone(), kind: Box::new(kind) } + } + + fn lower_tuple_subpats( + &mut self, + pats: &[hir_def::expr::PatId], + expected_len: usize, + ellipsis: Option, + ) -> Vec { + pats.iter() + .enumerate_and_adjust(expected_len, ellipsis) + .map(|(i, &subpattern)| FieldPat { + field: LocalFieldId::from_raw((i as u32).into()), + pattern: self.lower_pattern(subpattern), + }) + .collect() + } + + fn lower_patterns(&mut self, pats: &[hir_def::expr::PatId]) -> Vec { + pats.iter().map(|&p| self.lower_pattern(p)).collect() + } + + fn lower_variant_or_leaf( + &mut self, + pat: hir_def::expr::PatId, + ty: &Ty, + subpatterns: Vec, + ) -> PatKind { + let kind = match self.infer.variant_resolution_for_pat(pat) { + Some(variant_id) => { + if let VariantId::EnumVariantId(enum_variant) = variant_id { + let substs = match ty.kind(&Interner) { + TyKind::Adt(_, substs) | TyKind::FnDef(_, substs) => substs.clone(), + TyKind::Error => { + return PatKind::Wild; + } + _ => panic!("inappropriate type for def: {:?}", ty), + }; + PatKind::Variant { substs, enum_variant, subpatterns } + } else { + PatKind::Leaf { subpatterns } + } + } + None => { + self.errors.push(PatternError::Unimplemented); + PatKind::Wild + } + }; + // TODO: do we need PatKind::AscribeUserType ? + kind + } +} + #[cfg(test)] mod tests { use crate::diagnostics::tests::check_diagnostics; diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 248a379b3516..479e0dc73a6d 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -5,18 +5,18 @@ use std::{ }; use hir_def::{ - expr::{Expr, Literal, Pat, PatId, RecordFieldPat}, - find_path::find_path, - item_scope::ItemInNs, - path::Path, + expr::{Expr, Literal, RecordFieldPat}, type_ref::Mutability, - AttrDefId, EnumVariantId, HasModule, VariantId, + AttrDefId, EnumVariantId, HasModule, LocalFieldId, VariantId, }; use smallvec::{smallvec, SmallVec}; use crate::{AdtId, Interner, Scalar, Ty, TyExt, TyKind}; -use super::usefulness::{MatchCheckCtx, PatCtxt}; +use super::{ + usefulness::{MatchCheckCtx, PatCtxt}, + FieldPat, Pat, PatId, PatKind, +}; use self::Constructor::*; @@ -271,29 +271,18 @@ impl Constructor { /// Determines the constructor that the given pattern can be specialized to. pub(super) fn from_pat(cx: &MatchCheckCtx<'_>, pat: PatId) -> Self { let ty = cx.type_of(pat); - match &cx.pattern_arena.borrow()[pat] { - Pat::Bind { .. } | Pat::Wild => Wildcard, - Pat::Tuple { .. } | Pat::Ref { .. } | Pat::Box { .. } => Single, - Pat::Record { .. } | Pat::Path(_) | Pat::TupleStruct { .. } => { - // TODO: path to const - let variant_id = - cx.infer.variant_resolution_for_pat(pat).unwrap_or_else(|| todo!()); - match variant_id { - VariantId::EnumVariantId(id) => Variant(id), - VariantId::StructId(_) | VariantId::UnionId(_) => Single, - } - } - &Pat::Lit(expr_id) => match cx.body[expr_id] { - Expr::Literal(Literal::Bool(val)) => IntRange(IntRange::from_bool(val)), - _ => todo!(), - }, + match cx.pattern_arena.borrow()[pat].kind.as_ref() { + PatKind::Binding { .. } | PatKind::Wild => Wildcard, + PatKind::Leaf { .. } | PatKind::Deref { .. } => Single, + &PatKind::Variant { enum_variant, .. } => Variant(enum_variant), - Pat::Or(..) => panic!("bug: Or-pattern should have been expanded earlier on."), - Pat::Missing => todo!("Fail gracefully when there is an error in a pattern"), + //Todo + // &Pat::Lit(expr_id) => match cx.body[expr_id] { + // Expr::Literal(Literal::Bool(val)) => IntRange(IntRange::from_bool(val)), + // _ => todo!(), + // }, + PatKind::Or { .. } => panic!("bug: Or-pattern should have been expanded earlier on."), pat => todo!("Constructor::from_pat {:?}", pat), - // Pat::Range { start, end } => {} - // Pat::Slice { prefix, slice, suffix } => {} - // Pat::ConstBlock(_) => {} } } @@ -620,15 +609,15 @@ impl Fields { cx: &MatchCheckCtx<'_>, tys: impl IntoIterator, ) -> Self { - let wilds = tys.into_iter().map(|ty| (Pat::Wild, ty)); - let pats = wilds.map(|(pat, ty)| cx.alloc_pat(pat, ty)).collect(); + let wilds = tys.into_iter().map(Pat::wildcard_from_ty); + let pats = wilds.map(|pat| cx.alloc_pat(pat)).collect(); Fields::Vec(pats) } pub(crate) fn wildcards(pcx: PatCtxt<'_>, constructor: &Constructor) -> Self { let ty = pcx.ty; let cx = pcx.cx; - let wildcard_from_ty = |ty| cx.alloc_pat(Pat::Wild, ty); + let wildcard_from_ty = |ty| cx.alloc_pat(Pat::wildcard_from_ty(ty)); let ret = match constructor { Single | Variant(_) => match ty.kind(&Interner) { @@ -696,64 +685,60 @@ impl Fields { /// returns `Some(false)` pub(super) fn apply(self, pcx: PatCtxt<'_>, ctor: &Constructor) -> Pat { let subpatterns_and_indices = self.patterns_and_indices(); - let mut subpatterns = subpatterns_and_indices.iter().map(|&(_, p)| p); - // TODO witnesses are not yet used - const TODO: Pat = Pat::Wild; + let mut subpatterns = + subpatterns_and_indices.iter().map(|&(_, p)| pcx.cx.pattern_arena.borrow()[p].clone()); + // FIXME(iDawer) witnesses are not yet used + const UNIMPLEMENTED: PatKind = PatKind::Wild; - match ctor { + let pat = match ctor { Single | Variant(_) => match pcx.ty.kind(&Interner) { TyKind::Adt(..) | TyKind::Tuple(..) => { // We want the real indices here. - // TODO indices and ellipsis interaction, tests - let subpatterns = subpatterns_and_indices.iter().map(|&(_, pat)| pat).collect(); + let subpatterns = subpatterns_and_indices + .iter() + .map(|&(field, pat)| FieldPat { + field, + pattern: pcx.cx.pattern_arena.borrow()[pat].clone(), + }) + .collect(); if let Some((adt, substs)) = pcx.ty.as_adt() { - let item = ItemInNs::Types(adt.into()); - let path = find_path(pcx.cx.db.upcast(), item, pcx.cx.module) - .map(|mpath| Path::from_known_path(mpath, Vec::new()).into()); - match adt { - hir_def::AdtId::EnumId(id) => TODO, - hir_def::AdtId::StructId(id) => { - let variant_data = &pcx.cx.db.struct_data(id).variant_data; - let args = subpatterns_and_indices - .iter() - .zip(variant_data.fields().iter()) - .map(|(&(_, pat), (_, field_data))| RecordFieldPat { - name: field_data.name.clone(), - pat, - }) - .collect(); - Pat::Record { path, args, ellipsis: false } - } - hir_def::AdtId::UnionId(_) => Pat::Wild, + if let hir_def::AdtId::EnumId(_) = adt { + let enum_variant = match ctor { + &Variant(id) => id, + _ => unreachable!(), + }; + PatKind::Variant { substs: substs.clone(), enum_variant, subpatterns } + } else { + PatKind::Leaf { subpatterns } } } else { - Pat::Tuple { args: subpatterns, ellipsis: None } + PatKind::Leaf { subpatterns } } } // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should // be careful to reconstruct the correct constant pattern here. However a string // literal pattern will never be reported as a non-exhaustiveness witness, so we // can ignore this issue. - TyKind::Ref(..) => { - Pat::Ref { pat: subpatterns.next().unwrap(), mutability: Mutability::Shared } - } + TyKind::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() }, TyKind::Slice(..) | TyKind::Array(..) => { panic!("bug: bad slice pattern {:?} {:?}", ctor, pcx.ty) } - _ => Pat::Wild, + _ => PatKind::Wild, }, - Constructor::Slice(slice) => TODO, - Str(_) => TODO, - FloatRange(..) => TODO, - Constructor::IntRange(_) => TODO, - NonExhaustive => Pat::Wild, - Wildcard => Pat::Wild, + Constructor::Slice(slice) => UNIMPLEMENTED, + Str(_) => UNIMPLEMENTED, + FloatRange(..) => UNIMPLEMENTED, + Constructor::IntRange(_) => UNIMPLEMENTED, + NonExhaustive => PatKind::Wild, + Wildcard => return Pat::wildcard_from_ty(pcx.ty), Opaque => panic!("bug: we should not try to apply an opaque constructor"), Missing => { panic!("bug: trying to apply the `Missing` constructor; this should have been done in `apply_constructors`") } - } + }; + + Pat { ty: pcx.ty.clone(), kind: Box::new(pat) } } /// Returns the number of patterns. This is the same as the arity of the constructor used to @@ -765,9 +750,14 @@ impl Fields { } /// Returns the list of patterns along with the corresponding field indices. - fn patterns_and_indices(&self) -> SmallVec<[(usize, PatId); 2]> { + fn patterns_and_indices(&self) -> SmallVec<[(LocalFieldId, PatId); 2]> { match self { - Fields::Vec(pats) => pats.iter().copied().enumerate().collect(), + Fields::Vec(pats) => pats + .iter() + .copied() + .enumerate() + .map(|(i, p)| (LocalFieldId::from_raw((i as u32).into()), p)) + .collect(), } } @@ -779,8 +769,13 @@ impl Fields { /// Overrides some of the fields with the provided patterns. Exactly like /// `replace_fields_indexed`, except that it takes `FieldPat`s as input. - fn replace_with_fieldpats(&self, new_pats: impl IntoIterator) -> Self { - self.replace_fields_indexed(new_pats.into_iter().enumerate()) + fn replace_with_fieldpats( + &self, + new_pats: impl IntoIterator, + ) -> Self { + self.replace_fields_indexed( + new_pats.into_iter().map(|(field, pat)| (u32::from(field.into_raw()) as usize, pat)), + ) } /// Overrides some of the fields with the provided patterns. This is used when a pattern @@ -814,10 +809,7 @@ impl Fields { let tys: SmallVec<[Ty; 2]> = match self { Fields::Vec(pats) => pats.iter().copied().map(|pat| cx.type_of(pat)).collect(), }; - pats.into_iter() - .zip(tys.into_iter()) - .map(move |(pat, ty)| cx.alloc_pat(pat, &ty)) - .collect() + pats.into_iter().zip(tys.into_iter()).map(move |(pat, ty)| cx.alloc_pat(pat)).collect() }; match self { @@ -845,42 +837,24 @@ impl Fields { pat: PatId, cx: &MatchCheckCtx<'_>, ) -> Self { - match &cx.pattern_arena.borrow()[pat] { - Pat::Ref { pat: subpattern, .. } | Pat::Box { inner: subpattern } => { + // TODO: these alocations are so unfortunate (+1 for switching to references) + match cx.pattern_arena.borrow()[pat].kind.as_ref() { + PatKind::Deref { subpattern } => { assert_eq!(self.len(), 1); - Fields::from_single_pattern(*subpattern) + let subpattern = cx.pattern_arena.borrow_mut().alloc(subpattern.clone()); + Fields::from_single_pattern(subpattern) } - Pat::Tuple { args, ellipsis } | Pat::TupleStruct { args, ellipsis, .. } => { - // FIXME(iDawer) handle ellipsis. - // XXX(iDawer): in rustc, this is handled by HIR->TypedHIR lowering - // rustc_mir_build::thir::pattern::PatCtxt::lower_tuple_subpats(..) - self.replace_with_fieldpats(args.iter().copied()) - } - Pat::Record { args, ellipsis, .. } => { - let variant_id = - cx.infer.variant_resolution_for_pat(pat).unwrap_or_else(|| todo!()); - let variant_data = variant_id.variant_data(cx.db.upcast()); - - let new_pats = args.iter().map(|field_pat| { - // TODO: field lookup is inefficient - let raw = - variant_data.field(&field_pat.name).unwrap_or_else(|| todo!()).into_raw(); - let idx = u32::from(raw) as usize; - (idx, field_pat.pat) + PatKind::Leaf { subpatterns } | PatKind::Variant { subpatterns, .. } => { + let subpatterns = subpatterns.iter().map(|field_pat| { + ( + field_pat.field, + cx.pattern_arena.borrow_mut().alloc(field_pat.pattern.clone()), + ) }); - self.replace_fields_indexed(new_pats) + self.replace_with_fieldpats(subpatterns) } - Pat::Slice { .. } => { - todo!() - } - Pat::Missing - | Pat::Wild - | Pat::Or(_) - | Pat::Range { .. } - | Pat::Path(_) - | Pat::Lit(_) - | Pat::Bind { .. } - | Pat::ConstBlock(_) => self.clone(), + + PatKind::Wild | PatKind::Binding { .. } | PatKind::Or { .. } => self.clone(), } } } diff --git a/crates/hir_ty/src/diagnostics/pattern/pat_util.rs b/crates/hir_ty/src/diagnostics/pattern/pat_util.rs new file mode 100644 index 000000000000..f8ad4e7c6fc4 --- /dev/null +++ b/crates/hir_ty/src/diagnostics/pattern/pat_util.rs @@ -0,0 +1,52 @@ +use std::iter::{Enumerate, ExactSizeIterator}; + +pub struct EnumerateAndAdjust { + enumerate: Enumerate, + gap_pos: usize, + gap_len: usize, +} + +impl Iterator for EnumerateAndAdjust +where + I: Iterator, +{ + type Item = (usize, ::Item); + + fn next(&mut self) -> Option<(usize, ::Item)> { + self.enumerate + .next() + .map(|(i, elem)| (if i < self.gap_pos { i } else { i + self.gap_len }, elem)) + } + + fn size_hint(&self) -> (usize, Option) { + self.enumerate.size_hint() + } +} + +pub trait EnumerateAndAdjustIterator { + fn enumerate_and_adjust( + self, + expected_len: usize, + gap_pos: Option, + ) -> EnumerateAndAdjust + where + Self: Sized; +} + +impl EnumerateAndAdjustIterator for T { + fn enumerate_and_adjust( + self, + expected_len: usize, + gap_pos: Option, + ) -> EnumerateAndAdjust + where + Self: Sized, + { + let actual_len = self.len(); + EnumerateAndAdjust { + enumerate: self.enumerate(), + gap_pos: gap_pos.unwrap_or(expected_len), + gap_len: expected_len - actual_len, + } + } +} diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 2df87ccea146..28b9e71f8a74 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -3,11 +3,7 @@ use std::{cell::RefCell, iter::FromIterator, ops::Index, sync::Arc}; -use hir_def::{ - body::Body, - expr::{ExprId, Pat, PatId}, - HasModule, ModuleId, -}; +use hir_def::{body::Body, expr::ExprId, HasModule, ModuleId}; use la_arena::Arena; use once_cell::unsync::OnceCell; use rustc_hash::FxHashMap; @@ -15,7 +11,10 @@ use smallvec::{smallvec, SmallVec}; use crate::{db::HirDatabase, InferenceResult, Ty}; -use super::deconstruct_pat::{Constructor, Fields, SplitWildcard}; +use super::{ + deconstruct_pat::{Constructor, Fields, SplitWildcard}, + Pat, PatId, PatKind, +}; use self::{ helper::{Captures, PatIdExt}, @@ -55,14 +54,13 @@ impl<'a> MatchCheckCtx<'a> { false } - pub(super) fn alloc_pat(&self, pat: Pat, ty: &Ty) -> PatId { - self.pattern_arena.borrow_mut().alloc(pat, ty) + pub(super) fn alloc_pat(&self, pat: Pat) -> PatId { + self.pattern_arena.borrow_mut().alloc(pat) } /// Get type of a pattern. Handles expanded patterns. pub(super) fn type_of(&self, pat: PatId) -> Ty { - let type_of_expanded_pat = self.pattern_arena.borrow().type_of_epat.get(&pat).cloned(); - type_of_expanded_pat.unwrap_or_else(|| self.infer[pat].clone()) + self.pattern_arena.borrow()[pat].ty.clone() } } @@ -76,30 +74,40 @@ pub(super) struct PatCtxt<'a> { pub(super) is_top_level: bool, } -impl PatIdExt for PatId { - fn is_wildcard(self, cx: &MatchCheckCtx<'_>) -> bool { - matches!(cx.pattern_arena.borrow()[self], Pat::Bind { subpat: None, .. } | Pat::Wild) - } +pub(crate) fn expand_pattern(pat: Pat) -> Pat { + // TODO: LiteralExpander, it is about string literal patterns + pat +} +impl Pat { + fn is_wildcard(&self) -> bool { + matches!(*self.kind, PatKind::Binding { subpattern: None, .. } | PatKind::Wild) + } +} + +impl PatIdExt for PatId { fn is_or_pat(self, cx: &MatchCheckCtx<'_>) -> bool { - matches!(cx.pattern_arena.borrow()[self], Pat::Or(..)) + matches!(*cx.pattern_arena.borrow()[self].kind, PatKind::Or { .. }) } /// Recursively expand this pattern into its subpatterns. Only useful for or-patterns. fn expand_or_pat(self, cx: &MatchCheckCtx<'_>) -> Vec { - fn expand(pat: PatId, vec: &mut Vec, pat_arena: &PatternArena) { - if let Pat::Or(pats) = &pat_arena[pat] { - for &pat in pats { - expand(pat, vec, pat_arena); - } + fn expand(pat: PatId, vec: &mut Vec, mut pat_arena: &mut PatternArena) { + if let PatKind::Or { pats } = pat_arena[pat].kind.as_ref() { + // for pat in pats { + // // TODO(iDawer): Ugh, I want to go back to references (PatId -> &Pat) + // let pat = pat_arena.alloc(pat.clone()); + // expand(pat, vec, pat_arena); + // } + todo!() } else { vec.push(pat) } } - let pat_arena = cx.pattern_arena.borrow(); + let mut pat_arena = cx.pattern_arena.borrow_mut(); let mut pats = Vec::new(); - expand(self, &mut pats, &pat_arena); + expand(self, &mut pats, &mut pat_arena); pats } } @@ -866,7 +874,8 @@ pub(crate) fn compute_match_usefulness( }) .collect(); - let wild_pattern = cx.pattern_arena.borrow_mut().alloc(Pat::Wild, &cx.infer[cx.match_expr]); + let wild_pattern = + cx.pattern_arena.borrow_mut().alloc(Pat::wildcard_from_ty(&cx.infer[cx.match_expr])); let v = PatStack::from_pattern(wild_pattern); let usefulness = is_useful(cx, &matrix, &v, ConstructWitness, false, true); let non_exhaustiveness_witnesses = match usefulness { @@ -876,31 +885,7 @@ pub(crate) fn compute_match_usefulness( UsefulnessReport { arm_usefulness, non_exhaustiveness_witnesses } } -pub(crate) struct PatternArena { - arena: Arena, - /// Types of expanded patterns. - type_of_epat: FxHashMap, -} - -impl PatternArena { - pub(crate) fn clone_from(pats: &Arena) -> RefCell { - PatternArena { arena: pats.clone(), type_of_epat: Default::default() }.into() - } - - fn alloc(&mut self, pat: Pat, ty: &Ty) -> PatId { - let id = self.arena.alloc(pat); - self.type_of_epat.insert(id, ty.clone()); - id - } -} - -impl Index for PatternArena { - type Output = Pat; - - fn index(&self, pat: PatId) -> &Pat { - &self.arena[pat] - } -} +pub(crate) type PatternArena = Arena; mod helper { use hir_def::expr::{Pat, PatId}; @@ -908,7 +893,7 @@ mod helper { use super::MatchCheckCtx; pub(super) trait PatIdExt: Sized { - fn is_wildcard(self, cx: &MatchCheckCtx<'_>) -> bool; + // fn is_wildcard(self, cx: &MatchCheckCtx<'_>) -> bool; fn is_or_pat(self, cx: &MatchCheckCtx<'_>) -> bool; fn expand_or_pat(self, cx: &MatchCheckCtx<'_>) -> Vec; } From de6f430140a49e3ecf34dcb914326bb5b9789772 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 6 May 2021 13:15:40 +0500 Subject: [PATCH 14/35] Fix panics on pattern_arena.borrow with ugly cloning --- .../diagnostics/pattern/deconstruct_pat.rs | 19 +++++++++---------- .../src/diagnostics/pattern/usefulness.rs | 12 ++++++------ 2 files changed, 15 insertions(+), 16 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 479e0dc73a6d..ddf6b1198f7e 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -837,20 +837,19 @@ impl Fields { pat: PatId, cx: &MatchCheckCtx<'_>, ) -> Self { - // TODO: these alocations are so unfortunate (+1 for switching to references) - match cx.pattern_arena.borrow()[pat].kind.as_ref() { + // TODO: these alocations and clones are so unfortunate (+1 for switching to references) + let mut arena = cx.pattern_arena.borrow_mut(); + match arena[pat].kind.as_ref() { PatKind::Deref { subpattern } => { assert_eq!(self.len(), 1); - let subpattern = cx.pattern_arena.borrow_mut().alloc(subpattern.clone()); - Fields::from_single_pattern(subpattern) + let subpattern = subpattern.clone(); + Fields::from_single_pattern(arena.alloc(subpattern)) } PatKind::Leaf { subpatterns } | PatKind::Variant { subpatterns, .. } => { - let subpatterns = subpatterns.iter().map(|field_pat| { - ( - field_pat.field, - cx.pattern_arena.borrow_mut().alloc(field_pat.pattern.clone()), - ) - }); + let subpatterns = subpatterns.clone(); + let subpatterns = subpatterns + .iter() + .map(|field_pat| (field_pat.field, arena.alloc(field_pat.pattern.clone()))); self.replace_with_fieldpats(subpatterns) } diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 28b9e71f8a74..3bfb7afed040 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -94,12 +94,12 @@ impl PatIdExt for PatId { fn expand_or_pat(self, cx: &MatchCheckCtx<'_>) -> Vec { fn expand(pat: PatId, vec: &mut Vec, mut pat_arena: &mut PatternArena) { if let PatKind::Or { pats } = pat_arena[pat].kind.as_ref() { - // for pat in pats { - // // TODO(iDawer): Ugh, I want to go back to references (PatId -> &Pat) - // let pat = pat_arena.alloc(pat.clone()); - // expand(pat, vec, pat_arena); - // } - todo!() + let pats = pats.clone(); + for pat in pats { + // TODO(iDawer): Ugh, I want to go back to references (PatId -> &Pat) + let pat = pat_arena.alloc(pat.clone()); + expand(pat, vec, pat_arena); + } } else { vec.push(pat) } From e50ce67631bc8f8e28042112a924b73c6081dc71 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 6 May 2021 13:32:35 +0500 Subject: [PATCH 15/35] Do not do match check if lowering failed. --- crates/hir_ty/src/diagnostics/expr.rs | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index 8f141a308d2f..929c4a9ccb3b 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -388,14 +388,26 @@ impl<'a, 'b> ExprValidator<'a, 'b> { let pattern_arena = RefCell::new(PatternArena::new()); + let mut have_errors = false; let m_arms: Vec<_> = arms .iter() .map(|arm| usefulness::MatchArm { - pat: self.lower_pattern(arm.pat, &mut pattern_arena.borrow_mut(), db, &body), + pat: self.lower_pattern( + arm.pat, + &mut pattern_arena.borrow_mut(), + db, + &body, + &mut have_errors, + ), has_guard: arm.guard.is_some(), }) .collect(); + // Bail out early if lowering failed. + if have_errors { + return; + } + let cx = usefulness::MatchCheckCtx { module: self.owner.module(db.upcast()), match_expr, @@ -442,10 +454,15 @@ impl<'a, 'b> ExprValidator<'a, 'b> { pattern_arena: &mut PatternArena, db: &dyn HirDatabase, body: &Body, + have_errors: &mut bool, ) -> pattern::PatId { let mut patcx = pattern::PatCtxt::new(db, &self.infer, body); let pattern = patcx.lower_pattern(pat); - pattern_arena.alloc(expand_pattern(pattern)) + let pattern = pattern_arena.alloc(expand_pattern(pattern)); + if !patcx.errors.is_empty() { + *have_errors = true; + } + pattern } fn validate_results_in_tail_expr(&mut self, body_id: ExprId, id: ExprId, db: &dyn HirDatabase) { From e711abc29032ddd395b60fccc47063e49785168f Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 6 May 2021 17:18:51 +0500 Subject: [PATCH 16/35] Lower Pat::Path --- crates/hir_ty/src/diagnostics/pattern.rs | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 6646826b3303..5c9419d2cca7 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -99,6 +99,10 @@ impl<'a> PatCtxt<'a> { let kind = match self.body[pat] { hir_def::expr::Pat::Wild => PatKind::Wild, + hir_def::expr::Pat::Path(ref path) => { + return self.lower_path(pat, path); + } + hir_def::expr::Pat::Tuple { ref args, ellipsis } => { let arity = match *ty.kind(&Interner) { TyKind::Tuple(arity, _) => arity, @@ -193,6 +197,20 @@ impl<'a> PatCtxt<'a> { // TODO: do we need PatKind::AscribeUserType ? kind } + + fn lower_path(&mut self, pat: hir_def::expr::PatId, path: &hir_def::path::Path) -> Pat { + let ty = &self.infer[pat]; + + let pat_from_kind = |kind| Pat { ty: ty.clone(), kind: Box::new(kind) }; + + match self.infer.variant_resolution_for_pat(pat) { + Some(_) => pat_from_kind(self.lower_variant_or_leaf(pat, ty, Vec::new())), + None => { + self.errors.push(PatternError::Unimplemented); + pat_from_kind(PatKind::Wild) + } + } + } } #[cfg(test)] From d6d77e8a35cb2ac63b877f73bdf0ea6e6a1578e4 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 6 May 2021 17:26:05 +0500 Subject: [PATCH 17/35] Treat ctor of unhandled type as non-exhaustive. --- crates/hir_ty/src/diagnostics/pattern.rs | 18 ++++++++++++++++++ .../src/diagnostics/pattern/deconstruct_pat.rs | 10 ++++++---- 2 files changed, 24 insertions(+), 4 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 5c9419d2cca7..7b0b63d0bfa8 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -353,6 +353,24 @@ fn main() { //^^^^ Missing match arm } +"#, + ); + } + + #[test] + fn no_panic_at_unimplemented_subpattern_type() { + check_diagnostics( + r#" +struct S { a: char} +fn main(v: S) { + match v { S{ a } => {} } + match v { S{ a: x } => {} } + match v { S{ a: 'a' } => {} } + match v { S{..} => {} } + match v { _ => {} } + match v { } + //^ Missing match arm +} "#, ); } diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index ddf6b1198f7e..1319745ce147 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -419,6 +419,8 @@ impl SplitWildcard { let cx = pcx.cx; let make_range = |start, end, scalar| IntRange(IntRange::from_range(cx, start, end, scalar)); + // FIXME(iDawer) using NonExhaustive ctor for unhandled types + let unhandled = || smallvec![NonExhaustive]; // This determines the set of all possible constructors for the type `pcx.ty`. For numbers, // arrays and slices we use ranges and variable-length slices when appropriate. @@ -431,7 +433,7 @@ impl SplitWildcard { let all_ctors = match pcx.ty.kind(&Interner) { TyKind::Scalar(Scalar::Bool) => smallvec![make_range(0, 1, Scalar::Bool)], // TyKind::Array(..) if ... => todo!(), - TyKind::Array(..) | TyKind::Slice(..) => todo!(), + TyKind::Array(..) | TyKind::Slice(..) => unhandled(), &TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref _substs) => { let enum_data = cx.db.enum_data(enum_id); @@ -466,7 +468,7 @@ impl SplitWildcard { } else if cx.feature_exhaustive_patterns() { // If `exhaustive_patterns` is enabled, we exclude variants known to be // uninhabited. - todo!() + unhandled() } else { enum_data .variants @@ -475,8 +477,8 @@ impl SplitWildcard { .collect() } } - TyKind::Scalar(Scalar::Char) => todo!(), - TyKind::Scalar(Scalar::Int(..)) | TyKind::Scalar(Scalar::Uint(..)) => todo!(), + TyKind::Scalar(Scalar::Char) => unhandled(), + TyKind::Scalar(Scalar::Int(..)) | TyKind::Scalar(Scalar::Uint(..)) => unhandled(), TyKind::Never if !cx.feature_exhaustive_patterns() && !pcx.is_top_level => { smallvec![NonExhaustive] } From cf6f989a8d638b76ec7e14d00f7ed095b20ffed6 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Thu, 6 May 2021 19:39:27 +0500 Subject: [PATCH 18/35] Lower bool literals --- crates/hir_ty/src/diagnostics/pattern.rs | 19 +++++++++++++++ .../diagnostics/pattern/deconstruct_pat.rs | 23 ++++++++----------- 2 files changed, 29 insertions(+), 13 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 7b0b63d0bfa8..14dd736a6cb3 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -67,6 +67,11 @@ pub enum PatKind { subpattern: Pat, }, + // only bool for now + LiteralBool { + value: bool, + }, + /// An or-pattern, e.g. `p | q`. /// Invariant: `pats.len() >= 2`. Or { @@ -99,6 +104,8 @@ impl<'a> PatCtxt<'a> { let kind = match self.body[pat] { hir_def::expr::Pat::Wild => PatKind::Wild, + hir_def::expr::Pat::Lit(expr) => self.lower_lit(expr), + hir_def::expr::Pat::Path(ref path) => { return self.lower_path(pat, path); } @@ -211,6 +218,18 @@ impl<'a> PatCtxt<'a> { } } } + + fn lower_lit(&mut self, expr: hir_def::expr::ExprId) -> PatKind { + use hir_def::expr::{Expr, Literal::Bool}; + + match self.body[expr] { + Expr::Literal(Bool(value)) => PatKind::LiteralBool { value }, + _ => { + self.errors.push(PatternError::Unimplemented); + PatKind::Wild + } + } + } } #[cfg(test)] diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 1319745ce147..91b9c7184d81 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -275,14 +275,8 @@ impl Constructor { PatKind::Binding { .. } | PatKind::Wild => Wildcard, PatKind::Leaf { .. } | PatKind::Deref { .. } => Single, &PatKind::Variant { enum_variant, .. } => Variant(enum_variant), - - //Todo - // &Pat::Lit(expr_id) => match cx.body[expr_id] { - // Expr::Literal(Literal::Bool(val)) => IntRange(IntRange::from_bool(val)), - // _ => todo!(), - // }, + &PatKind::LiteralBool { value } => IntRange(IntRange::from_bool(value)), PatKind::Or { .. } => panic!("bug: Or-pattern should have been expanded earlier on."), - pat => todo!("Constructor::from_pat {:?}", pat), } } @@ -690,7 +684,7 @@ impl Fields { let mut subpatterns = subpatterns_and_indices.iter().map(|&(_, p)| pcx.cx.pattern_arena.borrow()[p].clone()); // FIXME(iDawer) witnesses are not yet used - const UNIMPLEMENTED: PatKind = PatKind::Wild; + const UNHANDLED: PatKind = PatKind::Wild; let pat = match ctor { Single | Variant(_) => match pcx.ty.kind(&Interner) { @@ -728,10 +722,10 @@ impl Fields { } _ => PatKind::Wild, }, - Constructor::Slice(slice) => UNIMPLEMENTED, - Str(_) => UNIMPLEMENTED, - FloatRange(..) => UNIMPLEMENTED, - Constructor::IntRange(_) => UNIMPLEMENTED, + Constructor::Slice(slice) => UNHANDLED, + Str(_) => UNHANDLED, + FloatRange(..) => UNHANDLED, + Constructor::IntRange(_) => UNHANDLED, NonExhaustive => PatKind::Wild, Wildcard => return Pat::wildcard_from_ty(pcx.ty), Opaque => panic!("bug: we should not try to apply an opaque constructor"), @@ -855,7 +849,10 @@ impl Fields { self.replace_with_fieldpats(subpatterns) } - PatKind::Wild | PatKind::Binding { .. } | PatKind::Or { .. } => self.clone(), + PatKind::Wild + | PatKind::Binding { .. } + | PatKind::LiteralBool { .. } + | PatKind::Or { .. } => self.clone(), } } } From a236bfa57a1a860e834498d6ca1e1fc1f857a3a4 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Fri, 7 May 2021 10:38:51 +0500 Subject: [PATCH 19/35] Lower binding pattern --- crates/hir_ty/src/diagnostics/pattern.rs | 30 +++++++++++++++++-- .../diagnostics/pattern/deconstruct_pat.rs | 7 +---- 2 files changed, 28 insertions(+), 9 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 14dd736a6cb3..99f32097f745 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -11,7 +11,7 @@ use la_arena::Idx; use crate::{db::HirDatabase, AdtId, InferenceResult, Interner, Substitution, Ty, TyKind}; -use self::{deconstruct_pat::ToDo, pat_util::EnumerateAndAdjustIterator}; +use self::pat_util::EnumerateAndAdjustIterator; pub type PatId = Idx; @@ -45,7 +45,6 @@ pub enum PatKind { /// `x`, `ref x`, `x @ P`, etc. Binding { subpattern: Option, - // todo: ToDo, }, /// `Foo(...)` or `Foo{...}` or `Foo`, where `Foo` is a variant name from an ADT with @@ -119,6 +118,10 @@ impl<'a> PatCtxt<'a> { PatKind::Leaf { subpatterns } } + hir_def::expr::Pat::Bind { subpat, .. } => { + PatKind::Binding { subpattern: self.lower_opt_pattern(subpat) } + } + hir_def::expr::Pat::TupleStruct { ref args, ellipsis, .. } => { let variant_data = match self.infer.variant_resolution_for_pat(pat) { Some(variant_id) => variant_id.variant_data(self.db.upcast()), @@ -175,6 +178,10 @@ impl<'a> PatCtxt<'a> { pats.iter().map(|&p| self.lower_pattern(p)).collect() } + fn lower_opt_pattern(&mut self, pat: Option) -> Option { + pat.map(|p| self.lower_pattern(p)) + } + fn lower_variant_or_leaf( &mut self, pat: hir_def::expr::PatId, @@ -383,13 +390,30 @@ fn main() { struct S { a: char} fn main(v: S) { match v { S{ a } => {} } - match v { S{ a: x } => {} } + match v { S{ a: _x } => {} } match v { S{ a: 'a' } => {} } match v { S{..} => {} } match v { _ => {} } match v { } //^ Missing match arm } +"#, + ); + } + + #[test] + fn binding() { + check_diagnostics( + r#" +fn main() { + match true { + _x @ true => {} + false => {} + } + //FIXME: false negative. + // Binding patterns should be expanded in `usefulness::expand_pattern()` + match true { _x @ true => {} } +} "#, ); } diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 91b9c7184d81..1c86ed59bdc9 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -801,12 +801,7 @@ impl Fields { cx: &MatchCheckCtx<'_>, pats: impl IntoIterator, ) -> Self { - let pats = { - let tys: SmallVec<[Ty; 2]> = match self { - Fields::Vec(pats) => pats.iter().copied().map(|pat| cx.type_of(pat)).collect(), - }; - pats.into_iter().zip(tys.into_iter()).map(move |(pat, ty)| cx.alloc_pat(pat)).collect() - }; + let pats = pats.into_iter().map(|pat| cx.alloc_pat(pat)).collect(); match self { Fields::Vec(_) => Fields::Vec(pats), From d7239e5ab4a3b88e9e79cc60d80eaf7300411e5a Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Fri, 7 May 2021 12:20:23 +0500 Subject: [PATCH 20/35] Fix visibility warnings --- crates/hir_ty/src/diagnostics/pattern.rs | 18 +++++++++--------- .../hir_ty/src/diagnostics/pattern/pat_util.rs | 4 ++-- .../src/diagnostics/pattern/usefulness.rs | 2 +- 3 files changed, 12 insertions(+), 12 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 99f32097f745..9f65e38d63da 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -4,7 +4,7 @@ mod deconstruct_pat; // TODO: find a better place for this? mod pat_util; -pub mod usefulness; +pub(crate) mod usefulness; use hir_def::{body::Body, EnumVariantId, LocalFieldId, VariantId}; use la_arena::Idx; @@ -13,7 +13,7 @@ use crate::{db::HirDatabase, AdtId, InferenceResult, Interner, Substitution, Ty, use self::pat_util::EnumerateAndAdjustIterator; -pub type PatId = Idx; +pub(crate) type PatId = Idx; #[derive(Clone, Debug)] pub(crate) enum PatternError { @@ -21,15 +21,15 @@ pub(crate) enum PatternError { } #[derive(Clone, Debug, PartialEq)] -pub struct FieldPat { - pub field: LocalFieldId, - pub pattern: Pat, +pub(crate) struct FieldPat { + pub(crate) field: LocalFieldId, + pub(crate) pattern: Pat, } #[derive(Clone, Debug, PartialEq)] -pub struct Pat { - pub ty: Ty, - pub kind: Box, +pub(crate) struct Pat { + pub(crate) ty: Ty, + pub(crate) kind: Box, } impl Pat { @@ -39,7 +39,7 @@ impl Pat { } #[derive(Clone, Debug, PartialEq)] -pub enum PatKind { +pub(crate) enum PatKind { Wild, /// `x`, `ref x`, `x @ P`, etc. diff --git a/crates/hir_ty/src/diagnostics/pattern/pat_util.rs b/crates/hir_ty/src/diagnostics/pattern/pat_util.rs index f8ad4e7c6fc4..eb0b07a52295 100644 --- a/crates/hir_ty/src/diagnostics/pattern/pat_util.rs +++ b/crates/hir_ty/src/diagnostics/pattern/pat_util.rs @@ -1,6 +1,6 @@ use std::iter::{Enumerate, ExactSizeIterator}; -pub struct EnumerateAndAdjust { +pub(crate) struct EnumerateAndAdjust { enumerate: Enumerate, gap_pos: usize, gap_len: usize, @@ -23,7 +23,7 @@ where } } -pub trait EnumerateAndAdjustIterator { +pub(crate) trait EnumerateAndAdjustIterator { fn enumerate_and_adjust( self, expected_len: usize, diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 3bfb7afed040..76dc4412f934 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -906,7 +906,7 @@ mod helper { /// [this comment]: https://github.com/rust-lang/rust/issues/34511#issuecomment-373423999 // FIXME(eddyb) false positive, the lifetime parameter is "phantom" but needed. #[allow(unused_lifetimes)] - pub trait Captures<'a> {} + pub(crate) trait Captures<'a> {} impl<'a, T: ?Sized> Captures<'a> for T {} } From 9b841a9a044d9d71cece62a3e44880325bc15f78 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Sat, 8 May 2021 23:06:17 +0500 Subject: [PATCH 21/35] Expand binding patterns. --- crates/hir_ty/src/diagnostics/pattern.rs | 98 ++++++++++++++++++- .../src/diagnostics/pattern/usefulness.rs | 18 +++- 2 files changed, 110 insertions(+), 6 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 9f65e38d63da..d98fb0867f40 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -239,6 +239,101 @@ impl<'a> PatCtxt<'a> { } } +pub(crate) trait PatternFoldable: Sized { + fn fold_with(&self, folder: &mut F) -> Self { + self.super_fold_with(folder) + } + + fn super_fold_with(&self, folder: &mut F) -> Self; +} + +pub(crate) trait PatternFolder: Sized { + fn fold_pattern(&mut self, pattern: &Pat) -> Pat { + pattern.super_fold_with(self) + } + + fn fold_pattern_kind(&mut self, kind: &PatKind) -> PatKind { + kind.super_fold_with(self) + } +} + +impl PatternFoldable for Box { + fn super_fold_with(&self, folder: &mut F) -> Self { + let content: T = (**self).fold_with(folder); + Box::new(content) + } +} + +impl PatternFoldable for Vec { + fn super_fold_with(&self, folder: &mut F) -> Self { + self.iter().map(|t| t.fold_with(folder)).collect() + } +} + +impl PatternFoldable for Option { + fn super_fold_with(&self, folder: &mut F) -> Self { + self.as_ref().map(|t| t.fold_with(folder)) + } +} + +macro_rules! clone_impls { + ($($ty:ty),+) => { + $( + impl PatternFoldable for $ty { + fn super_fold_with(&self, _: &mut F) -> Self { + Clone::clone(self) + } + } + )+ + } +} + +clone_impls! { LocalFieldId, Ty, Substitution, EnumVariantId } + +impl PatternFoldable for FieldPat { + fn super_fold_with(&self, folder: &mut F) -> Self { + FieldPat { field: self.field.fold_with(folder), pattern: self.pattern.fold_with(folder) } + } +} + +impl PatternFoldable for Pat { + fn fold_with(&self, folder: &mut F) -> Self { + folder.fold_pattern(self) + } + + fn super_fold_with(&self, folder: &mut F) -> Self { + Pat { ty: self.ty.fold_with(folder), kind: self.kind.fold_with(folder) } + } +} + +impl PatternFoldable for PatKind { + fn fold_with(&self, folder: &mut F) -> Self { + folder.fold_pattern_kind(self) + } + + fn super_fold_with(&self, folder: &mut F) -> Self { + match self { + PatKind::Wild => PatKind::Wild, + PatKind::Binding { subpattern } => { + PatKind::Binding { subpattern: subpattern.fold_with(folder) } + } + PatKind::Variant { substs, enum_variant, subpatterns } => PatKind::Variant { + substs: substs.fold_with(folder), + enum_variant: enum_variant.fold_with(folder), + subpatterns: subpatterns.fold_with(folder), + }, + PatKind::Leaf { subpatterns } => { + PatKind::Leaf { subpatterns: subpatterns.fold_with(folder) } + } + PatKind::Deref { subpattern } => { + PatKind::Deref { subpattern: subpattern.fold_with(folder) } + } + &PatKind::LiteralBool { value } => PatKind::LiteralBool { value }, + PatKind::Or { pats } => PatKind::Or { pats: pats.fold_with(folder) }, + } + } +} + #[cfg(test)] mod tests { use crate::diagnostics::tests::check_diagnostics; @@ -410,9 +505,8 @@ fn main() { _x @ true => {} false => {} } - //FIXME: false negative. - // Binding patterns should be expanded in `usefulness::expand_pattern()` match true { _x @ true => {} } + //^^^^ Missing match arm } "#, ); diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 76dc4412f934..ef2be7530351 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -9,11 +9,11 @@ use once_cell::unsync::OnceCell; use rustc_hash::FxHashMap; use smallvec::{smallvec, SmallVec}; -use crate::{db::HirDatabase, InferenceResult, Ty}; +use crate::{db::HirDatabase, InferenceResult, Interner, Ty}; use super::{ deconstruct_pat::{Constructor, Fields, SplitWildcard}, - Pat, PatId, PatKind, + Pat, PatId, PatKind, PatternFoldable, PatternFolder, }; use self::{ @@ -75,8 +75,18 @@ pub(super) struct PatCtxt<'a> { } pub(crate) fn expand_pattern(pat: Pat) -> Pat { - // TODO: LiteralExpander, it is about string literal patterns - pat + LiteralExpander.fold_pattern(&pat) +} + +struct LiteralExpander; + +impl PatternFolder for LiteralExpander { + fn fold_pattern(&mut self, pat: &Pat) -> Pat { + match (pat.ty.kind(&Interner), pat.kind.as_ref()) { + (_, PatKind::Binding { subpattern: Some(s), .. }) => s.fold_with(self), + _ => pat.super_fold_with(self), + } + } } impl Pat { From 49e016169fc8413e2734a655cbd55ebba2907b76 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Mon, 10 May 2021 13:22:13 +0500 Subject: [PATCH 22/35] Check pattern types. --- crates/hir_ty/src/diagnostics/expr.rs | 75 ++++++++++++------- crates/hir_ty/src/diagnostics/pattern.rs | 36 +++++++++ .../src/diagnostics/pattern/usefulness.rs | 2 +- 3 files changed, 84 insertions(+), 29 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index 929c4a9ccb3b..e4e9ab5c03b1 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -379,32 +379,58 @@ impl<'a, 'b> ExprValidator<'a, 'b> { let (body, source_map): (Arc, Arc) = db.body_with_source_map(self.owner); - let _match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() { + let match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() { return; } else { &infer.type_of_expr[match_expr] }; - // eprintln!("ExprValidator::validate_match2({:?})", _match_expr_ty.kind(&Interner)); let pattern_arena = RefCell::new(PatternArena::new()); - let mut have_errors = false; - let m_arms: Vec<_> = arms - .iter() - .map(|arm| usefulness::MatchArm { - pat: self.lower_pattern( - arm.pat, - &mut pattern_arena.borrow_mut(), - db, - &body, - &mut have_errors, - ), - has_guard: arm.guard.is_some(), - }) - .collect(); + let mut m_arms = Vec::new(); + let mut has_lowering_errors = false; + for arm in arms { + if let Some(pat_ty) = infer.type_of_pat.get(arm.pat) { + // We only include patterns whose type matches the type + // of the match expression. If we had a InvalidMatchArmPattern + // diagnostic or similar we could raise that in an else + // block here. + // + // When comparing the types, we also have to consider that rustc + // will automatically de-reference the match expression type if + // necessary. + // + // FIXME we should use the type checker for this. + if pat_ty == match_expr_ty + || match_expr_ty + .as_reference() + .map(|(match_expr_ty, ..)| match_expr_ty == pat_ty) + .unwrap_or(false) + { + // If we had a NotUsefulMatchArm diagnostic, we could + // check the usefulness of each pattern as we added it + // to the matrix here. + let m_arm = usefulness::MatchArm { + pat: self.lower_pattern( + arm.pat, + &mut pattern_arena.borrow_mut(), + db, + &body, + &mut has_lowering_errors, + ), + has_guard: arm.guard.is_some(), + }; + m_arms.push(m_arm); + if !has_lowering_errors { + continue; + } + } + } - // Bail out early if lowering failed. - if have_errors { + // If we can't resolve the type of a pattern, or the pattern type doesn't + // fit the match expression, we skip this diagnostic. Skipping the entire + // diagnostic rather than just not including this match arm is preferred + // to avoid the chance of false positives. return; } @@ -418,18 +444,11 @@ impl<'a, 'b> ExprValidator<'a, 'b> { }; let report = usefulness::compute_match_usefulness(&cx, &m_arms); - // TODO Report unreacheble arms - // let mut catchall = None; - // for (arm_index, (arm, is_useful)) in report.arm_usefulness.iter().enumerate() { - // match is_useful{ - // Unreachable => { - // } - // Reachable(_) => {} - // } - // } + // FIXME Report unreacheble arms + // https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/check_match.rs#L200-L201 let witnesses = report.non_exhaustiveness_witnesses; - eprintln!("compute_match_usefulness(..) -> {:?}", &witnesses); + // eprintln!("compute_match_usefulness(..) -> {:?}", &witnesses); if !witnesses.is_empty() { if let Ok(source_ptr) = source_map.expr_syntax(id) { let root = source_ptr.file_syntax(db.upcast()); diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index d98fb0867f40..38e4b53b7fb9 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -511,4 +511,40 @@ fn main() { "#, ); } + + /// These failing tests are narrowed down from "hir_ty::diagnostics::match_check::tests" + // TODO fix + mod failing { + use super::*; + + #[test] + fn never() { + check_diagnostics( + r#" +enum Never {} + +fn enum_ref(never: &Never) { + match never {} +} +"#, + ); + } + + #[test] + fn unknown_type() { + check_diagnostics( + r#" +enum Option { Some(T), None } + +fn main() { + // `Never` is deliberately not defined so that it's an uninferred type. + match Option::::None { + None => {} + Some(never) => {} + } +} +"#, + ); + } + } } diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index ef2be7530351..01a7fb0d9a1a 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -28,7 +28,7 @@ pub(crate) struct MatchCheckCtx<'a> { pub(crate) body: Arc, pub(crate) infer: &'a InferenceResult, pub(crate) db: &'a dyn HirDatabase, - /// Patterns from self.body.pats plus generated by the check. + /// Lowered patterns from self.body.pats plus generated by the check. pub(crate) pattern_arena: &'a RefCell, } From 466345ca81c9f8a17347671ca27856eb963858f4 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Mon, 10 May 2021 16:55:00 +0500 Subject: [PATCH 23/35] Clean up, more docs. --- crates/hir_def/src/path.rs | 5 +- crates/hir_ty/src/diagnostics/expr.rs | 1 - crates/hir_ty/src/diagnostics/pattern.rs | 25 +- .../diagnostics/pattern/deconstruct_pat.rs | 143 ++++---- .../src/diagnostics/pattern/usefulness.rs | 309 ++++++++++++++++-- 5 files changed, 381 insertions(+), 102 deletions(-) diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs index 4cdb5913deb5..f98622faac88 100644 --- a/crates/hir_def/src/path.rs +++ b/crates/hir_def/src/path.rs @@ -166,10 +166,7 @@ impl Path { } /// Converts a known mod path to `Path`. - pub fn from_known_path( - path: ModPath, - generic_args: Vec>>, - ) -> Path { + pub fn from_known_path(path: ModPath, generic_args: Vec>>) -> Path { Path { type_anchor: None, mod_path: Interned::new(path), generic_args } } diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index e4e9ab5c03b1..b321004acfd6 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -437,7 +437,6 @@ impl<'a, 'b> ExprValidator<'a, 'b> { let cx = usefulness::MatchCheckCtx { module: self.owner.module(db.upcast()), match_expr, - body, infer: &infer, db, pattern_arena: &pattern_arena, diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 38e4b53b7fb9..85c01b17868c 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -1,15 +1,18 @@ -#![deny(elided_lifetimes_in_paths)] -#![allow(unused)] // todo remove +//! Validation of matches. +//! +//! This module provides lowering from [hir_def::expr::Pat] to [self::Pat] and match +//! checking algorithm. +//! +//! It is a loose port of `rustc_mir_build::thir::pattern` module. mod deconstruct_pat; -// TODO: find a better place for this? mod pat_util; pub(crate) mod usefulness; use hir_def::{body::Body, EnumVariantId, LocalFieldId, VariantId}; use la_arena::Idx; -use crate::{db::HirDatabase, AdtId, InferenceResult, Interner, Substitution, Ty, TyKind}; +use crate::{db::HirDatabase, InferenceResult, Interner, Substitution, Ty, TyKind}; use self::pat_util::EnumerateAndAdjustIterator; @@ -38,6 +41,7 @@ impl Pat { } } +/// Close relative to `rustc_mir_build::thir::pattern::PatKind` #[derive(Clone, Debug, PartialEq)] pub(crate) enum PatKind { Wild, @@ -66,7 +70,7 @@ pub(crate) enum PatKind { subpattern: Pat, }, - // only bool for now + // FIXME: for now, only bool literals are implemented LiteralBool { value: bool, }, @@ -91,7 +95,7 @@ impl<'a> PatCtxt<'a> { } pub(crate) fn lower_pattern(&mut self, pat: hir_def::expr::PatId) -> Pat { - // TODO: pattern adjustments (implicit dereference) + // FIXME: implement pattern adjustments (implicit pattern dereference; "RFC 2005-match-ergonomics") // More info https://github.com/rust-lang/rust/issues/42640#issuecomment-313535089 let unadjusted_pat = self.lower_pattern_unadjusted(pat); unadjusted_pat @@ -141,7 +145,7 @@ impl<'a> PatCtxt<'a> { .iter() .map(|field| FieldPat { // XXX(iDawer): field lookup is inefficient - field: variant_data.field(&field.name).unwrap_or_else(|| todo!()), + field: variant_data.field(&field.name).unwrap(), pattern: self.lower_pattern(field.pat), }) .collect(); @@ -208,11 +212,10 @@ impl<'a> PatCtxt<'a> { PatKind::Wild } }; - // TODO: do we need PatKind::AscribeUserType ? kind } - fn lower_path(&mut self, pat: hir_def::expr::PatId, path: &hir_def::path::Path) -> Pat { + fn lower_path(&mut self, pat: hir_def::expr::PatId, _path: &hir_def::path::Path) -> Pat { let ty = &self.infer[pat]; let pat_from_kind = |kind| Pat { ty: ty.clone(), kind: Box::new(kind) }; @@ -338,8 +341,6 @@ impl PatternFoldable for PatKind { mod tests { use crate::diagnostics::tests::check_diagnostics; - use super::*; - #[test] fn unit() { check_diagnostics( @@ -372,8 +373,6 @@ fn main() { #[test] fn tuple_with_ellipsis() { - // TODO: test non-exhaustive match with ellipsis in the middle - // of a pattern, check reported witness check_diagnostics( r#" struct A; struct B; diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs index 1c86ed59bdc9..9fa82a952ac0 100644 --- a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs @@ -1,14 +1,54 @@ +//! [`super::usefulness`] explains most of what is happening in this file. As explained there, +//! values and patterns are made from constructors applied to fields. This file defines a +//! `Constructor` enum, a `Fields` struct, and various operations to manipulate them and convert +//! them from/to patterns. +//! +//! There's one idea that is not detailed in [`super::usefulness`] because the details are not +//! needed there: _constructor splitting_. +//! +//! # Constructor splitting +//! +//! The idea is as follows: given a constructor `c` and a matrix, we want to specialize in turn +//! with all the value constructors that are covered by `c`, and compute usefulness for each. +//! Instead of listing all those constructors (which is intractable), we group those value +//! constructors together as much as possible. Example: +//! +//! ``` +//! match (0, false) { +//! (0 ..=100, true) => {} // `p_1` +//! (50..=150, false) => {} // `p_2` +//! (0 ..=200, _) => {} // `q` +//! } +//! ``` +//! +//! The naive approach would try all numbers in the range `0..=200`. But we can be a lot more +//! clever: `0` and `1` for example will match the exact same rows, and return equivalent +//! witnesses. In fact all of `0..50` would. We can thus restrict our exploration to 4 +//! constructors: `0..50`, `50..=100`, `101..=150` and `151..=200`. That is enough and infinitely +//! more tractable. +//! +//! We capture this idea in a function `split(p_1 ... p_n, c)` which returns a list of constructors +//! `c'` covered by `c`. Given such a `c'`, we require that all value ctors `c''` covered by `c'` +//! return an equivalent set of witnesses after specializing and computing usefulness. +//! In the example above, witnesses for specializing by `c''` covered by `0..50` will only differ +//! in their first element. +//! +//! We usually also ask that the `c'` together cover all of the original `c`. However we allow +//! skipping some constructors as long as it doesn't change whether the resulting list of witnesses +//! is empty of not. We use this in the wildcard `_` case. +//! +//! Splitting is implemented in the [`Constructor::split`] function. We don't do splitting for +//! or-patterns; instead we just try the alternatives one-by-one. For details on splitting +//! wildcards, see [`SplitWildcard`]; for integer ranges, see [`SplitIntRange`]; for slices, see +//! [`SplitVarLenSlice`]. + use std::{ cmp::{max, min}, iter::once, ops::RangeInclusive, }; -use hir_def::{ - expr::{Expr, Literal, RecordFieldPat}, - type_ref::Mutability, - AttrDefId, EnumVariantId, HasModule, LocalFieldId, VariantId, -}; +use hir_def::{EnumVariantId, HasModule, LocalFieldId, VariantId}; use smallvec::{smallvec, SmallVec}; use crate::{AdtId, Interner, Scalar, Ty, TyExt, TyKind}; @@ -20,9 +60,21 @@ use super::{ use self::Constructor::*; +/// [Constructor] uses this in umimplemented variants. +/// It allows porting match expressions from upstream algorithm without losing semantics. #[derive(Copy, Clone, Debug, PartialEq, Eq)] -pub(super) enum ToDo {} +pub(super) enum Void {} +/// An inclusive interval, used for precise integer exhaustiveness checking. +/// `IntRange`s always store a contiguous range. This means that values are +/// encoded such that `0` encodes the minimum value for the integer, +/// regardless of the signedness. +/// For example, the pattern `-128..=127i8` is encoded as `0..=255`. +/// This makes comparisons and arithmetic on interval endpoints much more +/// straightforward. See `signed_bias` for details. +/// +/// `IntRange` is never used to encode an empty range or a "range" that wraps +/// around the (offset) space: i.e., `range.lo <= range.hi`. #[derive(Clone, Debug, PartialEq, Eq)] pub(super) struct IntRange { range: RangeInclusive, @@ -55,11 +107,11 @@ impl IntRange { } #[inline] - fn from_range(cx: &MatchCheckCtx<'_>, lo: u128, hi: u128, scalar_ty: Scalar) -> IntRange { + fn from_range(lo: u128, hi: u128, scalar_ty: Scalar) -> IntRange { if let Scalar::Bool = scalar_ty { IntRange { range: lo..=hi } } else { - todo!() + unimplemented!() } } @@ -188,13 +240,13 @@ impl SplitIntRange { /// A constructor for array and slice patterns. #[derive(Copy, Clone, Debug, PartialEq, Eq)] pub(super) struct Slice { - todo: ToDo, + _unimplemented: Void, } impl Slice { /// See `Constructor::is_covered_by` - fn is_covered_by(self, other: Self) -> bool { - todo!() + fn is_covered_by(self, _other: Self) -> bool { + unimplemented!() // never called as Slice contains Void } } @@ -205,6 +257,7 @@ impl Slice { /// `specialize_constructor` returns the list of fields corresponding to a pattern, given a /// constructor. `Constructor::apply` reconstructs the pattern from a pair of `Constructor` and /// `Fields`. +#[allow(dead_code)] #[derive(Clone, Debug, PartialEq)] pub(super) enum Constructor { /// The constructor for patterns that have a single constructor, like tuples, struct patterns @@ -215,9 +268,9 @@ pub(super) enum Constructor { /// Ranges of integer literal values (`2`, `2..=5` or `2..5`). IntRange(IntRange), /// Ranges of floating-point literal values (`2.0..=5.2`). - FloatRange(ToDo), + FloatRange(Void), /// String literals. Strings are not quite the same as `&[u8]` so we treat them separately. - Str(ToDo), + Str(Void), /// Array and slice patterns. Slice(Slice), /// Constants that must not be matched structurally. They are treated as black @@ -253,7 +306,7 @@ impl Constructor { } } - fn variant_id_for_adt(&self, adt: hir_def::AdtId, cx: &MatchCheckCtx<'_>) -> VariantId { + fn variant_id_for_adt(&self, adt: hir_def::AdtId) -> VariantId { match *self { Variant(id) => id.into(), Single => { @@ -270,7 +323,6 @@ impl Constructor { /// Determines the constructor that the given pattern can be specialized to. pub(super) fn from_pat(cx: &MatchCheckCtx<'_>, pat: PatId) -> Self { - let ty = cx.type_of(pat); match cx.pattern_arena.borrow()[pat].kind.as_ref() { PatKind::Binding { .. } | PatKind::Wild => Wildcard, PatKind::Leaf { .. } | PatKind::Deref { .. } => Single, @@ -312,7 +364,7 @@ impl Constructor { split_range.split(int_ranges.cloned()); split_range.iter().map(IntRange).collect() } - Slice(_) => todo!("Constructor::split Slice"), + Slice(_) => unimplemented!(), // Any other constructor can be used unchanged. _ => smallvec![self.clone()], } @@ -323,7 +375,7 @@ impl Constructor { /// this checks for inclusion. // We inline because this has a single call site in `Matrix::specialize_constructor`. #[inline] - pub(super) fn is_covered_by(&self, pcx: PatCtxt<'_>, other: &Self) -> bool { + pub(super) fn is_covered_by(&self, _pcx: PatCtxt<'_>, other: &Self) -> bool { // This must be kept in sync with `is_covered_by_any`. match (self, other) { // Wildcards cover anything @@ -336,10 +388,10 @@ impl Constructor { (IntRange(self_range), IntRange(other_range)) => self_range.is_covered_by(other_range), (FloatRange(..), FloatRange(..)) => { - todo!() + unimplemented!() } - (Str(self_val), Str(other_val)) => { - todo!() + (Str(..), Str(..)) => { + unimplemented!() } (Slice(self_slice), Slice(other_slice)) => self_slice.is_covered_by(*other_slice), @@ -358,7 +410,7 @@ impl Constructor { /// Faster version of `is_covered_by` when applied to many constructors. `used_ctors` is /// assumed to be built from `matrix.head_ctors()` with wildcards filtered out, and `self` is /// assumed to have been split from a wildcard. - fn is_covered_by_any(&self, pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bool { + fn is_covered_by_any(&self, _pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bool { if used_ctors.is_empty() { return false; } @@ -411,9 +463,10 @@ pub(super) struct SplitWildcard { impl SplitWildcard { pub(super) fn new(pcx: PatCtxt<'_>) -> Self { let cx = pcx.cx; - let make_range = - |start, end, scalar| IntRange(IntRange::from_range(cx, start, end, scalar)); - // FIXME(iDawer) using NonExhaustive ctor for unhandled types + let make_range = |start, end, scalar| IntRange(IntRange::from_range(start, end, scalar)); + + // Unhandled types are treated as non-exhaustive. Being explicit here instead of falling + // to catchall arm to ease further implementation. let unhandled = || smallvec![NonExhaustive]; // This determines the set of all possible constructors for the type `pcx.ty`. For numbers, @@ -426,7 +479,7 @@ impl SplitWildcard { // `cx.is_uninhabited()`). let all_ctors = match pcx.ty.kind(&Interner) { TyKind::Scalar(Scalar::Bool) => smallvec![make_range(0, 1, Scalar::Bool)], - // TyKind::Array(..) if ... => todo!(), + // TyKind::Array(..) if ... => unhandled(), TyKind::Array(..) | TyKind::Slice(..) => unhandled(), &TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref _substs) => { let enum_data = cx.db.enum_data(enum_id); @@ -556,26 +609,6 @@ impl SplitWildcard { } } -#[test] -fn it_works2() {} - -/// Some fields need to be explicitly hidden away in certain cases; see the comment above the -/// `Fields` struct. This struct represents such a potentially-hidden field. -#[derive(Debug, Copy, Clone)] -pub(super) enum FilteredField { - Kept(PatId), - Hidden, -} - -impl FilteredField { - fn kept(self) -> Option { - match self { - FilteredField::Kept(p) => Some(p), - FilteredField::Hidden => None, - } - } -} - /// A value can be decomposed into a constructor applied to some fields. This struct represents /// those fields, generalized to allow patterns in each field. See also `Constructor`. /// This is constructed from a constructor using [`Fields::wildcards()`]. @@ -623,14 +656,13 @@ impl Fields { } TyKind::Ref(.., rty) => Fields::from_single_pattern(wildcard_from_ty(rty)), TyKind::Adt(AdtId(adt), substs) => { - let adt_is_box = false; // TODO(iDawer): handle box patterns + let adt_is_box = false; // TODO(iDawer): implement this if adt_is_box { // Use T as the sub pattern type of Box. - let ty = substs.at(&Interner, 0).assert_ty_ref(&Interner); - Fields::from_single_pattern(wildcard_from_ty(ty)) + let subst_ty = substs.at(&Interner, 0).assert_ty_ref(&Interner); + Fields::from_single_pattern(wildcard_from_ty(subst_ty)) } else { - let variant_id = constructor.variant_id_for_adt(*adt, cx); - let variant = variant_id.variant_data(cx.db.upcast()); + let variant_id = constructor.variant_id_for_adt(*adt); let adt_is_local = variant_id.module(cx.db.upcast()).krate() == cx.module.krate(); // Whether we must not match the fields of this variant exhaustively. @@ -655,8 +687,8 @@ impl Fields { } _ => panic!("Unexpected type for `Single` constructor: {:?}", ty), }, - Slice(slice) => { - todo!() + Slice(..) => { + unimplemented!() } Str(..) | FloatRange(..) | IntRange(..) | NonExhaustive | Opaque | Missing | Wildcard => Fields::Vec(Default::default()), @@ -722,7 +754,7 @@ impl Fields { } _ => PatKind::Wild, }, - Constructor::Slice(slice) => UNHANDLED, + Constructor::Slice(_) => UNHANDLED, Str(_) => UNHANDLED, FloatRange(..) => UNHANDLED, Constructor::IntRange(_) => UNHANDLED, @@ -828,7 +860,7 @@ impl Fields { pat: PatId, cx: &MatchCheckCtx<'_>, ) -> Self { - // TODO: these alocations and clones are so unfortunate (+1 for switching to references) + // FIXME(iDawer): these alocations and clones are so unfortunate (+1 for switching to references) let mut arena = cx.pattern_arena.borrow_mut(); match arena[pat].kind.as_ref() { PatKind::Deref { subpattern } => { @@ -860,6 +892,3 @@ fn is_field_list_non_exhaustive(variant_id: VariantId, cx: &MatchCheckCtx<'_>) - }; cx.db.attrs(attr_def_id).by_key("non_exhaustive").exists() } - -#[test] -fn it_works() {} diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs index 01a7fb0d9a1a..b01e3557cac0 100644 --- a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/pattern/usefulness.rs @@ -1,9 +1,279 @@ -// Based on rust-lang/rust 1.52.0-nightly (25c15cdbe 2021-04-22) -// https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs +//! Based on rust-lang/rust 1.52.0-nightly (25c15cdbe 2021-04-22) +//! https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs +//! +//! ----- +//! +//! This file includes the logic for exhaustiveness and reachability checking for pattern-matching. +//! Specifically, given a list of patterns for a type, we can tell whether: +//! (a) each pattern is reachable (reachability) +//! (b) the patterns cover every possible value for the type (exhaustiveness) +//! +//! The algorithm implemented here is a modified version of the one described in [this +//! paper](http://moscova.inria.fr/~maranget/papers/warn/index.html). We have however generalized +//! it to accommodate the variety of patterns that Rust supports. We thus explain our version here, +//! without being as rigorous. +//! +//! +//! # Summary +//! +//! The core of the algorithm is the notion of "usefulness". A pattern `q` is said to be *useful* +//! relative to another pattern `p` of the same type if there is a value that is matched by `q` and +//! not matched by `p`. This generalizes to many `p`s: `q` is useful w.r.t. a list of patterns +//! `p_1 .. p_n` if there is a value that is matched by `q` and by none of the `p_i`. We write +//! `usefulness(p_1 .. p_n, q)` for a function that returns a list of such values. The aim of this +//! file is to compute it efficiently. +//! +//! This is enough to compute reachability: a pattern in a `match` expression is reachable iff it +//! is useful w.r.t. the patterns above it: +//! ```rust +//! match x { +//! Some(_) => ..., +//! None => ..., // reachable: `None` is matched by this but not the branch above +//! Some(0) => ..., // unreachable: all the values this matches are already matched by +//! // `Some(_)` above +//! } +//! ``` +//! +//! This is also enough to compute exhaustiveness: a match is exhaustive iff the wildcard `_` +//! pattern is _not_ useful w.r.t. the patterns in the match. The values returned by `usefulness` +//! are used to tell the user which values are missing. +//! ```rust +//! match x { +//! Some(0) => ..., +//! None => ..., +//! // not exhaustive: `_` is useful because it matches `Some(1)` +//! } +//! ``` +//! +//! The entrypoint of this file is the [`compute_match_usefulness`] function, which computes +//! reachability for each match branch and exhaustiveness for the whole match. +//! +//! +//! # Constructors and fields +//! +//! Note: we will often abbreviate "constructor" as "ctor". +//! +//! The idea that powers everything that is done in this file is the following: a (matcheable) +//! value is made from a constructor applied to a number of subvalues. Examples of constructors are +//! `Some`, `None`, `(,)` (the 2-tuple constructor), `Foo {..}` (the constructor for a struct +//! `Foo`), and `2` (the constructor for the number `2`). This is natural when we think of +//! pattern-matching, and this is the basis for what follows. +//! +//! Some of the ctors listed above might feel weird: `None` and `2` don't take any arguments. +//! That's ok: those are ctors that take a list of 0 arguments; they are the simplest case of +//! ctors. We treat `2` as a ctor because `u64` and other number types behave exactly like a huge +//! `enum`, with one variant for each number. This allows us to see any matcheable value as made up +//! from a tree of ctors, each having a set number of children. For example: `Foo { bar: None, +//! baz: Ok(0) }` is made from 4 different ctors, namely `Foo{..}`, `None`, `Ok` and `0`. +//! +//! This idea can be extended to patterns: they are also made from constructors applied to fields. +//! A pattern for a given type is allowed to use all the ctors for values of that type (which we +//! call "value constructors"), but there are also pattern-only ctors. The most important one is +//! the wildcard (`_`), and the others are integer ranges (`0..=10`), variable-length slices (`[x, +//! ..]`), and or-patterns (`Ok(0) | Err(_)`). Examples of valid patterns are `42`, `Some(_)`, `Foo +//! { bar: Some(0) | None, baz: _ }`. Note that a binder in a pattern (e.g. `Some(x)`) matches the +//! same values as a wildcard (e.g. `Some(_)`), so we treat both as wildcards. +//! +//! From this deconstruction we can compute whether a given value matches a given pattern; we +//! simply look at ctors one at a time. Given a pattern `p` and a value `v`, we want to compute +//! `matches!(v, p)`. It's mostly straightforward: we compare the head ctors and when they match +//! we compare their fields recursively. A few representative examples: +//! +//! - `matches!(v, _) := true` +//! - `matches!((v0, v1), (p0, p1)) := matches!(v0, p0) && matches!(v1, p1)` +//! - `matches!(Foo { bar: v0, baz: v1 }, Foo { bar: p0, baz: p1 }) := matches!(v0, p0) && matches!(v1, p1)` +//! - `matches!(Ok(v0), Ok(p0)) := matches!(v0, p0)` +//! - `matches!(Ok(v0), Err(p0)) := false` (incompatible variants) +//! - `matches!(v, 1..=100) := matches!(v, 1) || ... || matches!(v, 100)` +//! - `matches!([v0], [p0, .., p1]) := false` (incompatible lengths) +//! - `matches!([v0, v1, v2], [p0, .., p1]) := matches!(v0, p0) && matches!(v2, p1)` +//! - `matches!(v, p0 | p1) := matches!(v, p0) || matches!(v, p1)` +//! +//! Constructors, fields and relevant operations are defined in the [`super::deconstruct_pat`] module. +//! +//! Note: this constructors/fields distinction may not straightforwardly apply to every Rust type. +//! For example a value of type `Rc` can't be deconstructed that way, and `&str` has an +//! infinitude of constructors. There are also subtleties with visibility of fields and +//! uninhabitedness and various other things. The constructors idea can be extended to handle most +//! of these subtleties though; caveats are documented where relevant throughout the code. +//! +//! Whether constructors cover each other is computed by [`Constructor::is_covered_by`]. +//! +//! +//! # Specialization +//! +//! Recall that we wish to compute `usefulness(p_1 .. p_n, q)`: given a list of patterns `p_1 .. +//! p_n` and a pattern `q`, all of the same type, we want to find a list of values (called +//! "witnesses") that are matched by `q` and by none of the `p_i`. We obviously don't just +//! enumerate all possible values. From the discussion above we see that we can proceed +//! ctor-by-ctor: for each value ctor of the given type, we ask "is there a value that starts with +//! this constructor and matches `q` and none of the `p_i`?". As we saw above, there's a lot we can +//! say from knowing only the first constructor of our candidate value. +//! +//! Let's take the following example: +//! ``` +//! match x { +//! Enum::Variant1(_) => {} // `p1` +//! Enum::Variant2(None, 0) => {} // `p2` +//! Enum::Variant2(Some(_), 0) => {} // `q` +//! } +//! ``` +//! +//! We can easily see that if our candidate value `v` starts with `Variant1` it will not match `q`. +//! If `v = Variant2(v0, v1)` however, whether or not it matches `p2` and `q` will depend on `v0` +//! and `v1`. In fact, such a `v` will be a witness of usefulness of `q` exactly when the tuple +//! `(v0, v1)` is a witness of usefulness of `q'` in the following reduced match: +//! +//! ``` +//! match x { +//! (None, 0) => {} // `p2'` +//! (Some(_), 0) => {} // `q'` +//! } +//! ``` +//! +//! This motivates a new step in computing usefulness, that we call _specialization_. +//! Specialization consist of filtering a list of patterns for those that match a constructor, and +//! then looking into the constructor's fields. This enables usefulness to be computed recursively. +//! +//! Instead of acting on a single pattern in each row, we will consider a list of patterns for each +//! row, and we call such a list a _pattern-stack_. The idea is that we will specialize the +//! leftmost pattern, which amounts to popping the constructor and pushing its fields, which feels +//! like a stack. We note a pattern-stack simply with `[p_1 ... p_n]`. +//! Here's a sequence of specializations of a list of pattern-stacks, to illustrate what's +//! happening: +//! ``` +//! [Enum::Variant1(_)] +//! [Enum::Variant2(None, 0)] +//! [Enum::Variant2(Some(_), 0)] +//! //==>> specialize with `Variant2` +//! [None, 0] +//! [Some(_), 0] +//! //==>> specialize with `Some` +//! [_, 0] +//! //==>> specialize with `true` (say the type was `bool`) +//! [0] +//! //==>> specialize with `0` +//! [] +//! ``` +//! +//! The function `specialize(c, p)` takes a value constructor `c` and a pattern `p`, and returns 0 +//! or more pattern-stacks. If `c` does not match the head constructor of `p`, it returns nothing; +//! otherwise if returns the fields of the constructor. This only returns more than one +//! pattern-stack if `p` has a pattern-only constructor. +//! +//! - Specializing for the wrong constructor returns nothing +//! +//! `specialize(None, Some(p0)) := []` +//! +//! - Specializing for the correct constructor returns a single row with the fields +//! +//! `specialize(Variant1, Variant1(p0, p1, p2)) := [[p0, p1, p2]]` +//! +//! `specialize(Foo{..}, Foo { bar: p0, baz: p1 }) := [[p0, p1]]` +//! +//! - For or-patterns, we specialize each branch and concatenate the results +//! +//! `specialize(c, p0 | p1) := specialize(c, p0) ++ specialize(c, p1)` +//! +//! - We treat the other pattern constructors as if they were a large or-pattern of all the +//! possibilities: +//! +//! `specialize(c, _) := specialize(c, Variant1(_) | Variant2(_, _) | ...)` +//! +//! `specialize(c, 1..=100) := specialize(c, 1 | ... | 100)` +//! +//! `specialize(c, [p0, .., p1]) := specialize(c, [p0, p1] | [p0, _, p1] | [p0, _, _, p1] | ...)` +//! +//! - If `c` is a pattern-only constructor, `specialize` is defined on a case-by-case basis. See +//! the discussion about constructor splitting in [`super::deconstruct_pat`]. +//! +//! +//! We then extend this function to work with pattern-stacks as input, by acting on the first +//! column and keeping the other columns untouched. +//! +//! Specialization for the whole matrix is done in [`Matrix::specialize_constructor`]. Note that +//! or-patterns in the first column are expanded before being stored in the matrix. Specialization +//! for a single patstack is done from a combination of [`Constructor::is_covered_by`] and +//! [`PatStack::pop_head_constructor`]. The internals of how it's done mostly live in the +//! [`Fields`] struct. +//! +//! +//! # Computing usefulness +//! +//! We now have all we need to compute usefulness. The inputs to usefulness are a list of +//! pattern-stacks `p_1 ... p_n` (one per row), and a new pattern_stack `q`. The paper and this +//! file calls the list of patstacks a _matrix_. They must all have the same number of columns and +//! the patterns in a given column must all have the same type. `usefulness` returns a (possibly +//! empty) list of witnesses of usefulness. These witnesses will also be pattern-stacks. +//! +//! - base case: `n_columns == 0`. +//! Since a pattern-stack functions like a tuple of patterns, an empty one functions like the +//! unit type. Thus `q` is useful iff there are no rows above it, i.e. if `n == 0`. +//! +//! - inductive case: `n_columns > 0`. +//! We need a way to list the constructors we want to try. We will be more clever in the next +//! section but for now assume we list all value constructors for the type of the first column. +//! +//! - for each such ctor `c`: +//! +//! - for each `q'` returned by `specialize(c, q)`: +//! +//! - we compute `usefulness(specialize(c, p_1) ... specialize(c, p_n), q')` +//! +//! - for each witness found, we revert specialization by pushing the constructor `c` on top. +//! +//! - We return the concatenation of all the witnesses found, if any. +//! +//! Example: +//! ``` +//! [Some(true)] // p_1 +//! [None] // p_2 +//! [Some(_)] // q +//! //==>> try `None`: `specialize(None, q)` returns nothing +//! //==>> try `Some`: `specialize(Some, q)` returns a single row +//! [true] // p_1' +//! [_] // q' +//! //==>> try `true`: `specialize(true, q')` returns a single row +//! [] // p_1'' +//! [] // q'' +//! //==>> base case; `n != 0` so `q''` is not useful. +//! //==>> go back up a step +//! [true] // p_1' +//! [_] // q' +//! //==>> try `false`: `specialize(false, q')` returns a single row +//! [] // q'' +//! //==>> base case; `n == 0` so `q''` is useful. We return the single witness `[]` +//! witnesses: +//! [] +//! //==>> undo the specialization with `false` +//! witnesses: +//! [false] +//! //==>> undo the specialization with `Some` +//! witnesses: +//! [Some(false)] +//! //==>> we have tried all the constructors. The output is the single witness `[Some(false)]`. +//! ``` +//! +//! This computation is done in [`is_useful`]. In practice we don't care about the list of +//! witnesses when computing reachability; we only need to know whether any exist. We do keep the +//! witnesses when computing exhaustiveness to report them to the user. +//! +//! +//! # Making usefulness tractable: constructor splitting +//! +//! We're missing one last detail: which constructors do we list? Naively listing all value +//! constructors cannot work for types like `u64` or `&str`, so we need to be more clever. The +//! first obvious insight is that we only want to list constructors that are covered by the head +//! constructor of `q`. If it's a value constructor, we only try that one. If it's a pattern-only +//! constructor, we use the final clever idea for this algorithm: _constructor splitting_, where we +//! group together constructors that behave the same. +//! +//! The details are not necessary to understand this file, so we explain them in +//! [`super::deconstruct_pat`]. Splitting is done by the [`Constructor::split`] function. -use std::{cell::RefCell, iter::FromIterator, ops::Index, sync::Arc}; +use std::{cell::RefCell, iter::FromIterator}; -use hir_def::{body::Body, expr::ExprId, HasModule, ModuleId}; +use hir_def::{expr::ExprId, HasModule, ModuleId}; use la_arena::Arena; use once_cell::unsync::OnceCell; use rustc_hash::FxHashMap; @@ -16,16 +286,11 @@ use super::{ Pat, PatId, PatKind, PatternFoldable, PatternFolder, }; -use self::{ - helper::{Captures, PatIdExt}, - Usefulness::*, - WitnessPreference::*, -}; +use self::{helper::PatIdExt, Usefulness::*, WitnessPreference::*}; pub(crate) struct MatchCheckCtx<'a> { pub(crate) module: ModuleId, pub(crate) match_expr: ExprId, - pub(crate) body: Arc, pub(crate) infer: &'a InferenceResult, pub(crate) db: &'a dyn HirDatabase, /// Lowered patterns from self.body.pats plus generated by the check. @@ -33,7 +298,7 @@ pub(crate) struct MatchCheckCtx<'a> { } impl<'a> MatchCheckCtx<'a> { - pub(super) fn is_uninhabited(&self, ty: &Ty) -> bool { + pub(super) fn is_uninhabited(&self, _ty: &Ty) -> bool { // FIXME(iDawer) implement exhaustive_patterns feature. More info in: // Tracking issue for RFC 1872: exhaustive_patterns feature https://github.com/rust-lang/rust/issues/51085 false @@ -90,7 +355,7 @@ impl PatternFolder for LiteralExpander { } impl Pat { - fn is_wildcard(&self) -> bool { + fn _is_wildcard(&self) -> bool { matches!(*self.kind, PatKind::Binding { subpattern: None, .. } | PatKind::Wild) } } @@ -102,11 +367,11 @@ impl PatIdExt for PatId { /// Recursively expand this pattern into its subpatterns. Only useful for or-patterns. fn expand_or_pat(self, cx: &MatchCheckCtx<'_>) -> Vec { - fn expand(pat: PatId, vec: &mut Vec, mut pat_arena: &mut PatternArena) { + fn expand(pat: PatId, vec: &mut Vec, pat_arena: &mut PatternArena) { if let PatKind::Or { pats } = pat_arena[pat].kind.as_ref() { let pats = pats.clone(); for pat in pats { - // TODO(iDawer): Ugh, I want to go back to references (PatId -> &Pat) + // FIXME(iDawer): Ugh, I want to go back to references (PatId -> &Pat) let pat = pat_arena.alloc(pat.clone()); expand(pat, vec, pat_arena); } @@ -157,10 +422,6 @@ impl PatStack { self.head_ctor.get_or_init(|| Constructor::from_pat(cx, self.head())) } - fn iter(&self) -> impl Iterator + '_ { - self.pats.iter().copied() - } - // Recursively expand the first pattern into its subpatterns. Only useful if the pattern is an // or-pattern. Panics if `self` is empty. fn expand_or_pat(&self, cx: &MatchCheckCtx<'_>) -> impl Iterator + '_ { @@ -224,7 +485,7 @@ impl Matrix { } /// Number of columns of this matrix. `None` is the matrix is empty. - pub(super) fn column_count(&self) -> Option { + pub(super) fn _column_count(&self) -> Option { self.patterns.get(0).map(|r| r.len()) } @@ -770,7 +1031,6 @@ fn is_useful( assert!(rows.iter().all(|r| r.len() == v.len())); // FIXME(Nadrieril): Hack to work around type normalization issues (see rust-lang/rust#72476). - // TODO(iDawer): ty.strip_references() ? let ty = matrix.heads().next().map_or(cx.type_of(v.head()), |r| cx.type_of(r)); let pcx = PatCtxt { cx, ty: &ty, is_top_level }; @@ -848,7 +1108,7 @@ pub(crate) enum Reachability { /// The output of checking a match for exhaustiveness and arm reachability. pub(crate) struct UsefulnessReport { /// For each arm of the input, whether that arm is reachable after the arms above it. - pub(crate) arm_usefulness: Vec<(MatchArm, Reachability)>, + pub(crate) _arm_usefulness: Vec<(MatchArm, Reachability)>, /// If the match is exhaustive, this is empty. If not, this contains witnesses for the lack of /// exhaustiveness. pub(crate) non_exhaustiveness_witnesses: Vec, @@ -892,14 +1152,12 @@ pub(crate) fn compute_match_usefulness( WithWitnesses(pats) => pats.into_iter().map(Witness::single_pattern).collect(), NoWitnesses(_) => panic!("bug"), }; - UsefulnessReport { arm_usefulness, non_exhaustiveness_witnesses } + UsefulnessReport { _arm_usefulness: arm_usefulness, non_exhaustiveness_witnesses } } pub(crate) type PatternArena = Arena; mod helper { - use hir_def::expr::{Pat, PatId}; - use super::MatchCheckCtx; pub(super) trait PatIdExt: Sized { @@ -920,6 +1178,3 @@ mod helper { impl<'a, T: ?Sized> Captures<'a> for T {} } - -#[test] -fn it_works() {} From 7d675eda80c5f1eb4a9fe7d374023d71721bf2f1 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Mon, 10 May 2021 22:40:35 +0500 Subject: [PATCH 24/35] Don't panic on a pattern of unresolved ADT variant. --- crates/hir_ty/src/diagnostics/match_check.rs | 1 + crates/hir_ty/src/diagnostics/pattern.rs | 63 ++++---------------- 2 files changed, 14 insertions(+), 50 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index e8dd669bf6d9..52e9a5b1b3f7 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -1357,6 +1357,7 @@ fn enum_(never: Never) { } fn enum_ref(never: &Never) { match never {} + //^^^^^ Missing match arm } fn bang(never: !) { match never {} diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 85c01b17868c..4f88dfe60b02 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -21,6 +21,7 @@ pub(crate) type PatId = Idx; #[derive(Clone, Debug)] pub(crate) enum PatternError { Unimplemented, + UnresolvedVariant, } #[derive(Clone, Debug, PartialEq)] @@ -103,6 +104,7 @@ impl<'a> PatCtxt<'a> { fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat { let ty = &self.infer[pat]; + let variant = self.infer.variant_resolution_for_pat(pat); let kind = match self.body[pat] { hir_def::expr::Pat::Wild => PatKind::Wild, @@ -126,21 +128,14 @@ impl<'a> PatCtxt<'a> { PatKind::Binding { subpattern: self.lower_opt_pattern(subpat) } } - hir_def::expr::Pat::TupleStruct { ref args, ellipsis, .. } => { - let variant_data = match self.infer.variant_resolution_for_pat(pat) { - Some(variant_id) => variant_id.variant_data(self.db.upcast()), - None => panic!("tuple struct pattern not applied to an ADT {:?}", ty), - }; - let subpatterns = - self.lower_tuple_subpats(args, variant_data.fields().len(), ellipsis); + hir_def::expr::Pat::TupleStruct { ref args, ellipsis, .. } if variant.is_some() => { + let expected_len = variant.unwrap().variant_data(self.db.upcast()).fields().len(); + let subpatterns = self.lower_tuple_subpats(args, expected_len, ellipsis); self.lower_variant_or_leaf(pat, ty, subpatterns) } - hir_def::expr::Pat::Record { ref args, .. } => { - let variant_data = match self.infer.variant_resolution_for_pat(pat) { - Some(variant_id) => variant_id.variant_data(self.db.upcast()), - None => panic!("record pattern not applied to an ADT {:?}", ty), - }; + hir_def::expr::Pat::Record { ref args, .. } if variant.is_some() => { + let variant_data = variant.unwrap().variant_data(self.db.upcast()); let subpatterns = args .iter() .map(|field| FieldPat { @@ -151,6 +146,10 @@ impl<'a> PatCtxt<'a> { .collect(); self.lower_variant_or_leaf(pat, ty, subpatterns) } + hir_def::expr::Pat::TupleStruct { .. } | hir_def::expr::Pat::Record { .. } => { + self.errors.push(PatternError::UnresolvedVariant); + PatKind::Wild + } hir_def::expr::Pat::Or(ref pats) => PatKind::Or { pats: self.lower_patterns(pats) }, @@ -208,7 +207,7 @@ impl<'a> PatCtxt<'a> { } } None => { - self.errors.push(PatternError::Unimplemented); + self.errors.push(PatternError::UnresolvedVariant); PatKind::Wild } }; @@ -223,7 +222,7 @@ impl<'a> PatCtxt<'a> { match self.infer.variant_resolution_for_pat(pat) { Some(_) => pat_from_kind(self.lower_variant_or_leaf(pat, ty, Vec::new())), None => { - self.errors.push(PatternError::Unimplemented); + self.errors.push(PatternError::UnresolvedVariant); pat_from_kind(PatKind::Wild) } } @@ -510,40 +509,4 @@ fn main() { "#, ); } - - /// These failing tests are narrowed down from "hir_ty::diagnostics::match_check::tests" - // TODO fix - mod failing { - use super::*; - - #[test] - fn never() { - check_diagnostics( - r#" -enum Never {} - -fn enum_ref(never: &Never) { - match never {} -} -"#, - ); - } - - #[test] - fn unknown_type() { - check_diagnostics( - r#" -enum Option { Some(T), None } - -fn main() { - // `Never` is deliberately not defined so that it's an uninferred type. - match Option::::None { - None => {} - Some(never) => {} - } -} -"#, - ); - } - } } From 894b4c64ffdb280a38c1ea2e9be145ca308965fd Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Tue, 11 May 2021 16:15:35 +0500 Subject: [PATCH 25/35] Include old tests --- crates/hir_ty/src/diagnostics/pattern.rs | 740 +++++++++++++++++++---- 1 file changed, 634 insertions(+), 106 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs index 4f88dfe60b02..f8d2e9baa99f 100644 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ b/crates/hir_ty/src/diagnostics/pattern.rs @@ -3,7 +3,7 @@ //! This module provides lowering from [hir_def::expr::Pat] to [self::Pat] and match //! checking algorithm. //! -//! It is a loose port of `rustc_mir_build::thir::pattern` module. +//! It is modeled on the rustc module `rustc_mir_build::thir::pattern`. mod deconstruct_pat; mod pat_util; @@ -341,110 +341,32 @@ mod tests { use crate::diagnostics::tests::check_diagnostics; #[test] - fn unit() { + fn empty_tuple() { check_diagnostics( r#" fn main() { - match () { () => {} } - match () { _ => {} } - match () { } + match () { } //^^ Missing match arm + match (()) { } + //^^^^ Missing match arm + + match () { _ => (), } + match () { () => (), } + match (()) { (()) => (), } } "#, ); } #[test] - fn tuple_of_units() { + fn tuple_of_two_empty_tuple() { check_diagnostics( r#" fn main() { - match ((), ()) { ((), ()) => {} } - match ((), ()) { ((), _) => {} } - match ((), ()) { (_, _) => {} } - match ((), ()) { _ => {} } - match ((), ()) { } + match ((), ()) { } //^^^^^^^^ Missing match arm -} -"#, - ); - } - #[test] - fn tuple_with_ellipsis() { - check_diagnostics( - r#" -struct A; struct B; -fn main(v: (A, (), B)) { - match v { (A, ..) => {} } - match v { (.., B) => {} } - match v { (A, .., B) => {} } - match v { (..) => {} } - match v { } - //^ Missing match arm -} -"#, - ); - } - - #[test] - fn strukt() { - check_diagnostics( - r#" -struct A; struct B; -struct S { a: A, b: B} -fn main(v: S) { - match v { S { a, b } => {} } - match v { S { a: _, b: _ } => {} } - match v { S { .. } => {} } - match v { _ => {} } - match v { } - //^ Missing match arm -} -"#, - ); - } - - #[test] - fn c_enum() { - check_diagnostics( - r#" -enum E { A, B } -fn main(v: E) { - match v { E::A | E::B => {} } - match v { _ => {} } - match v { E::A => {} } - //^ Missing match arm - match v { } - //^ Missing match arm -} -"#, - ); - } - - #[test] - fn enum_() { - check_diagnostics( - r#" -struct A; struct B; -enum E { Tuple(A, B), Struct{ a: A, b: B } } -fn main(v: E) { - match v { - E::Tuple(a, b) => {} - E::Struct{ a, b } => {} - } - match v { - E::Tuple(_, _) => {} - E::Struct{..} => {} - } - match v { - E::Tuple(..) => {} - _ => {} - } - match v { E::Tuple(..) => {} } - //^ Missing match arm - match v { } - //^ Missing match arm + match ((), ()) { ((), ()) => (), } } "#, ); @@ -454,23 +376,601 @@ fn main(v: E) { fn boolean() { check_diagnostics( r#" -fn main() { - match true { - true => {} - false => {} +fn test_main() { + match false { } + //^^^^^ Missing match arm + match false { true => (), } + //^^^^^ Missing match arm + match (false, true) {} + //^^^^^^^^^^^^^ Missing match arm + match (false, true) { (true, true) => (), } + //^^^^^^^^^^^^^ Missing match arm + match (false, true) { + //^^^^^^^^^^^^^ Missing match arm + (false, true) => (), + (false, false) => (), + (true, false) => (), } - match true { - true | false => {} - } - match true { - true => {} - _ => {} - } - match true {} - //^^^^ Missing match arm - match true { true => {} } - //^^^^ Missing match arm + match (false, true) { (true, _x) => (), } + //^^^^^^^^^^^^^ Missing match arm + match false { true => (), false => (), } + match (false, true) { + (false, _) => (), + (true, false) => (), + (_, true) => (), + } + match (false, true) { + (true, true) => (), + (true, false) => (), + (false, true) => (), + (false, false) => (), + } + match (false, true) { + (true, _x) => (), + (false, true) => (), + (false, false) => (), + } + match (false, true, false) { + (false, ..) => (), + (true, ..) => (), + } + match (false, true, false) { + (.., false) => (), + (.., true) => (), + } + match (false, true, false) { (..) => (), } +} +"#, + ); + } + + #[test] + fn tuple_of_tuple_and_bools() { + check_diagnostics( + r#" +fn main() { + match (false, ((), false)) {} + //^^^^^^^^^^^^^^^^^^^^ Missing match arm + match (false, ((), false)) { (true, ((), true)) => (), } + //^^^^^^^^^^^^^^^^^^^^ Missing match arm + match (false, ((), false)) { (true, _) => (), } + //^^^^^^^^^^^^^^^^^^^^ Missing match arm + + match (false, ((), false)) { + (true, ((), true)) => (), + (true, ((), false)) => (), + (false, ((), true)) => (), + (false, ((), false)) => (), + } + match (false, ((), false)) { + (true, ((), true)) => (), + (true, ((), false)) => (), + (false, _) => (), + } +} +"#, + ); + } + + #[test] + fn enums() { + check_diagnostics( + r#" +enum Either { A, B, } + +fn main() { + match Either::A { } + //^^^^^^^^^ Missing match arm + match Either::B { Either::A => (), } + //^^^^^^^^^ Missing match arm + + match &Either::B { + //^^^^^^^^^^ Missing match arm + Either::A => (), + } + + match Either::B { + Either::A => (), Either::B => (), + } + match &Either::B { + Either::A => (), Either::B => (), + } +} +"#, + ); + } + + #[test] + fn enum_containing_bool() { + check_diagnostics( + r#" +enum Either { A(bool), B } + +fn main() { + match Either::B { } + //^^^^^^^^^ Missing match arm + match Either::B { + //^^^^^^^^^ Missing match arm + Either::A(true) => (), Either::B => () + } + + match Either::B { + Either::A(true) => (), + Either::A(false) => (), + Either::B => (), + } + match Either::B { + Either::B => (), + _ => (), + } + match Either::B { + Either::A(_) => (), + Either::B => (), + } + +} + "#, + ); + } + + #[test] + fn enum_different_sizes() { + check_diagnostics( + r#" +enum Either { A(bool), B(bool, bool) } + +fn main() { + match Either::A(false) { + //^^^^^^^^^^^^^^^^ Missing match arm + Either::A(_) => (), + Either::B(false, _) => (), + } + + match Either::A(false) { + Either::A(_) => (), + Either::B(true, _) => (), + Either::B(false, _) => (), + } + match Either::A(false) { + Either::A(true) | Either::A(false) => (), + Either::B(true, _) => (), + Either::B(false, _) => (), + } +} +"#, + ); + } + + #[test] + fn tuple_of_enum_no_diagnostic() { + check_diagnostics( + r#" +enum Either { A(bool), B(bool, bool) } +enum Either2 { C, D } + +fn main() { + match (Either::A(false), Either2::C) { + (Either::A(true), _) | (Either::A(false), _) => (), + (Either::B(true, _), Either2::C) => (), + (Either::B(false, _), Either2::C) => (), + (Either::B(_, _), Either2::D) => (), + } +} +"#, + ); + } + + #[test] + fn or_pattern_no_diagnostic() { + check_diagnostics( + r#" +enum Either {A, B} + +fn main() { + match (Either::A, Either::B) { + (Either::A | Either::B, _) => (), + } +}"#, + ) + } + + #[test] + fn mismatched_types() { + // Match statements with arms that don't match the + // expression pattern do not fire this diagnostic. + check_diagnostics( + r#" +enum Either { A, B } +enum Either2 { C, D } + +fn main() { + match Either::A { + Either2::C => (), + Either2::D => (), + } + match (true, false) { + (true, false, true) => (), + (true) => (), + } + match (0) { () => () } + match Unresolved::Bar { Unresolved::Baz => () } +} + "#, + ); + } + + #[test] + fn malformed_match_arm_tuple_enum_missing_pattern() { + // We are testing to be sure we don't panic here when the match + // arm `Either::B` is missing its pattern. + check_diagnostics( + r#" +enum Either { A, B(u32) } + +fn main() { + match Either::A { + Either::A => (), + Either::B() => (), + } +} +"#, + ); + } + + #[test] + fn expr_diverges() { + check_diagnostics( + r#" +enum Either { A, B } + +fn main() { + match loop {} { + Either::A => (), + Either::B => (), + } + match loop {} { + Either::A => (), + } + match loop { break Foo::A } { + //^^^^^^^^^^^^^^^^^^^^^ Missing match arm + Either::A => (), + } + match loop { break Foo::A } { + Either::A => (), + Either::B => (), + } +} +"#, + ); + } + + #[test] + fn expr_partially_diverges() { + check_diagnostics( + r#" +enum Either { A(T), B } + +fn foo() -> Either { Either::B } +fn main() -> u32 { + match foo() { + Either::A(val) => val, + Either::B => 0, + } +} +"#, + ); + } + + #[test] + fn enum_record() { + check_diagnostics( + r#" +enum Either { A { foo: bool }, B } + +fn main() { + let a = Either::A { foo: true }; + match a { } + //^ Missing match arm + match a { Either::A { foo: true } => () } + //^ Missing match arm + match a { + Either::A { } => (), + //^^^^^^^^^ Missing structure fields: + // | - foo + Either::B => (), + } + match a { + //^ Missing match arm + Either::A { } => (), + } //^^^^^^^^^ Missing structure fields: + // | - foo + + match a { + Either::A { foo: true } => (), + Either::A { foo: false } => (), + Either::B => (), + } + match a { + Either::A { foo: _ } => (), + Either::B => (), + } +} +"#, + ); + } + + #[test] + fn enum_record_fields_out_of_order() { + check_diagnostics( + r#" +enum Either { + A { foo: bool, bar: () }, + B, +} + +fn main() { + let a = Either::A { foo: true, bar: () }; + match a { + //^ Missing match arm + Either::A { bar: (), foo: false } => (), + Either::A { foo: true, bar: () } => (), + } + + match a { + Either::A { bar: (), foo: false } => (), + Either::A { foo: true, bar: () } => (), + Either::B => (), + } +} +"#, + ); + } + + #[test] + fn enum_record_ellipsis() { + check_diagnostics( + r#" +enum Either { + A { foo: bool, bar: bool }, + B, +} + +fn main() { + let a = Either::B; + match a { + //^ Missing match arm + Either::A { foo: true, .. } => (), + Either::B => (), + } + match a { + //^ Missing match arm + Either::A { .. } => (), + } + + match a { + Either::A { foo: true, .. } => (), + Either::A { foo: false, .. } => (), + Either::B => (), + } + + match a { + Either::A { .. } => (), + Either::B => (), + } +} +"#, + ); + } + + #[test] + fn enum_tuple_partial_ellipsis() { + check_diagnostics( + r#" +enum Either { + A(bool, bool, bool, bool), + B, +} + +fn main() { + match Either::B { + //^^^^^^^^^ Missing match arm + Either::A(true, .., true) => (), + Either::A(true, .., false) => (), + Either::A(false, .., false) => (), + Either::B => (), + } + match Either::B { + //^^^^^^^^^ Missing match arm + Either::A(true, .., true) => (), + Either::A(true, .., false) => (), + Either::A(.., true) => (), + Either::B => (), + } + + match Either::B { + Either::A(true, .., true) => (), + Either::A(true, .., false) => (), + Either::A(false, .., true) => (), + Either::A(false, .., false) => (), + Either::B => (), + } + match Either::B { + Either::A(true, .., true) => (), + Either::A(true, .., false) => (), + Either::A(.., true) => (), + Either::A(.., false) => (), + Either::B => (), + } +} +"#, + ); + } + + #[test] + fn never() { + check_diagnostics( + r#" +enum Never {} + +fn enum_(never: Never) { + match never {} +} +fn enum_ref(never: &Never) { + match never {} + //^^^^^ Missing match arm +} +fn bang(never: !) { + match never {} +} +"#, + ); + } + + #[test] + fn unknown_type() { + check_diagnostics( + r#" +enum Option { Some(T), None } + +fn main() { + // `Never` is deliberately not defined so that it's an uninferred type. + match Option::::None { + None => (), + Some(never) => match never {}, + } +} +"#, + ); + } + + #[test] + fn tuple_of_bools_with_ellipsis_at_end_missing_arm() { + check_diagnostics( + r#" +fn main() { + match (false, true, false) { + //^^^^^^^^^^^^^^^^^^^^ Missing match arm + (false, ..) => (), + } +}"#, + ); + } + + #[test] + fn tuple_of_bools_with_ellipsis_at_beginning_missing_arm() { + check_diagnostics( + r#" +fn main() { + match (false, true, false) { + //^^^^^^^^^^^^^^^^^^^^ Missing match arm + (.., false) => (), + } +}"#, + ); + } + + #[test] + fn tuple_of_bools_with_ellipsis_in_middle_missing_arm() { + check_diagnostics( + r#" +fn main() { + match (false, true, false) { + //^^^^^^^^^^^^^^^^^^^^ Missing match arm + (true, .., false) => (), + } +}"#, + ); + } + + #[test] + fn record_struct() { + check_diagnostics( + r#"struct Foo { a: bool } +fn main(f: Foo) { + match f {} + //^ Missing match arm + match f { Foo { a: true } => () } + //^ Missing match arm + match &f { Foo { a: true } => () } + //^^ Missing match arm + match f { Foo { a: _ } => () } + match f { + Foo { a: true } => (), + Foo { a: false } => (), + } + match &f { + Foo { a: true } => (), + Foo { a: false } => (), + } +} +"#, + ); + } + + #[test] + fn tuple_struct() { + check_diagnostics( + r#"struct Foo(bool); +fn main(f: Foo) { + match f {} + //^ Missing match arm + match f { Foo(true) => () } + //^ Missing match arm + match f { + Foo(true) => (), + Foo(false) => (), + } +} +"#, + ); + } + + #[test] + fn unit_struct() { + check_diagnostics( + r#"struct Foo; +fn main(f: Foo) { + match f {} + //^ Missing match arm + match f { Foo => () } +} +"#, + ); + } + + #[test] + fn record_struct_ellipsis() { + check_diagnostics( + r#"struct Foo { foo: bool, bar: bool } +fn main(f: Foo) { + match f { Foo { foo: true, .. } => () } + //^ Missing match arm + match f { + //^ Missing match arm + Foo { foo: true, .. } => (), + Foo { bar: false, .. } => () + } + match f { Foo { .. } => () } + match f { + Foo { foo: true, .. } => (), + Foo { foo: false, .. } => () + } +} +"#, + ); + } + + #[test] + fn internal_or() { + check_diagnostics( + r#" +fn main() { + enum Either { A(bool), B } + match Either::B { + //^^^^^^^^^ Missing match arm + Either::A(true | false) => (), + } } "#, ); @@ -483,7 +983,7 @@ fn main() { struct S { a: char} fn main(v: S) { match v { S{ a } => {} } - match v { S{ a: _x } => {} } + match v { S{ a: _x } => {} } match v { S{ a: 'a' } => {} } match v { S{..} => {} } match v { _ => {} } @@ -509,4 +1009,32 @@ fn main() { "#, ); } + + mod false_negatives { + //! The implementation of match checking here is a work in progress. As we roll this out, we + //! prefer false negatives to false positives (ideally there would be no false positives). This + //! test module should document known false negatives. Eventually we will have a complete + //! implementation of match checking and this module will be empty. + //! + //! The reasons for documenting known false negatives: + //! + //! 1. It acts as a backlog of work that can be done to improve the behavior of the system. + //! 2. It ensures the code doesn't panic when handling these cases. + use super::*; + + #[test] + fn integers() { + // We don't currently check integer exhaustiveness. + check_diagnostics( + r#" +fn main() { + match 5 { + 10 => (), + 11..20 => (), + } +} +"#, + ); + } + } } From e84efc4a4656e54a4f08b99592d5d98ac5726449 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Tue, 11 May 2021 17:18:16 +0500 Subject: [PATCH 26/35] Replace the old match checking algorithm --- crates/hir_ty/src/diagnostics.rs | 2 - crates/hir_ty/src/diagnostics/expr.rs | 119 +- crates/hir_ty/src/diagnostics/match_check.rs | 1165 +++++------------ .../deconstruct_pat.rs | 0 .../{pattern => match_check}/pat_util.rs | 0 .../{pattern => match_check}/usefulness.rs | 0 crates/hir_ty/src/diagnostics/pattern.rs | 1040 --------------- 7 files changed, 355 insertions(+), 1971 deletions(-) rename crates/hir_ty/src/diagnostics/{pattern => match_check}/deconstruct_pat.rs (100%) rename crates/hir_ty/src/diagnostics/{pattern => match_check}/pat_util.rs (100%) rename crates/hir_ty/src/diagnostics/{pattern => match_check}/usefulness.rs (100%) delete mode 100644 crates/hir_ty/src/diagnostics/pattern.rs diff --git a/crates/hir_ty/src/diagnostics.rs b/crates/hir_ty/src/diagnostics.rs index 87a3594c52c8..283894704473 100644 --- a/crates/hir_ty/src/diagnostics.rs +++ b/crates/hir_ty/src/diagnostics.rs @@ -1,8 +1,6 @@ //! Type inference-based diagnostics. mod expr; -#[allow(unused)] //todo mod match_check; -mod pattern; mod unsafe_check; mod decl_check; diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index b321004acfd6..c6015d236515 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -4,7 +4,9 @@ use std::{cell::RefCell, sync::Arc}; -use hir_def::{expr::Statement, path::path, resolver::HasResolver, AssocItemId, DefWithBodyId}; +use hir_def::{ + expr::Statement, path::path, resolver::HasResolver, AssocItemId, DefWithBodyId, HasModule, +}; use hir_expand::name; use rustc_hash::FxHashSet; use syntax::{ast, AstPtr}; @@ -12,7 +14,10 @@ use syntax::{ast, AstPtr}; use crate::{ db::HirDatabase, diagnostics::{ - match_check::{is_useful, MatchCheckCtx, Matrix, PatStack, Usefulness}, + match_check::{ + self, + usefulness::{compute_match_usefulness, expand_pattern, MatchCheckCtx, PatternArena}, + }, MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkOrSomeInTailExpr, MissingPatFields, RemoveThisSemicolon, }, @@ -26,13 +31,7 @@ pub(crate) use hir_def::{ LocalFieldId, VariantId, }; -use super::{ - pattern::{ - self, - usefulness::{expand_pattern, PatternArena}, - }, - ReplaceFilterMapNextWithFindMap, -}; +use super::ReplaceFilterMapNextWithFindMap; pub(super) struct ExprValidator<'a, 'b: 'a> { owner: DefWithBodyId, @@ -68,7 +67,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> { match expr { Expr::Match { expr, arms } => { - self.validate_match2(id, *expr, arms, db, self.infer.clone()); + self.validate_match(id, *expr, arms, db, self.infer.clone()); } Expr::Call { .. } | Expr::MethodCall { .. } => { self.validate_call(db, id, expr); @@ -283,7 +282,6 @@ impl<'a, 'b> ExprValidator<'a, 'b> { } } - #[allow(dead_code)] fn validate_match( &mut self, id: ExprId, @@ -301,90 +299,6 @@ impl<'a, 'b> ExprValidator<'a, 'b> { &infer.type_of_expr[match_expr] }; - let cx = MatchCheckCtx { match_expr, body, infer: infer.clone(), db }; - let pats = arms.iter().map(|arm| arm.pat); - - let mut seen = Matrix::empty(); - for pat in pats { - if let Some(pat_ty) = infer.type_of_pat.get(pat) { - // We only include patterns whose type matches the type - // of the match expression. If we had a InvalidMatchArmPattern - // diagnostic or similar we could raise that in an else - // block here. - // - // When comparing the types, we also have to consider that rustc - // will automatically de-reference the match expression type if - // necessary. - // - // FIXME we should use the type checker for this. - if (pat_ty == match_expr_ty - || match_expr_ty - .as_reference() - .map(|(match_expr_ty, ..)| match_expr_ty == pat_ty) - .unwrap_or(false)) - && types_of_subpatterns_do_match(pat, &cx.body, &infer) - { - // If we had a NotUsefulMatchArm diagnostic, we could - // check the usefulness of each pattern as we added it - // to the matrix here. - let v = PatStack::from_pattern(pat); - seen.push(&cx, v); - continue; - } - } - - // If we can't resolve the type of a pattern, or the pattern type doesn't - // fit the match expression, we skip this diagnostic. Skipping the entire - // diagnostic rather than just not including this match arm is preferred - // to avoid the chance of false positives. - return; - } - - match is_useful(&cx, &seen, &PatStack::from_wild()) { - Ok(Usefulness::Useful) => (), - // if a wildcard pattern is not useful, then all patterns are covered - Ok(Usefulness::NotUseful) => return, - // this path is for unimplemented checks, so we err on the side of not - // reporting any errors - _ => return, - } - - if let Ok(source_ptr) = source_map.expr_syntax(id) { - let root = source_ptr.file_syntax(db.upcast()); - if let ast::Expr::MatchExpr(match_expr) = &source_ptr.value.to_node(&root) { - if let (Some(match_expr), Some(arms)) = - (match_expr.expr(), match_expr.match_arm_list()) - { - self.sink.push(MissingMatchArms { - file: source_ptr.file_id, - match_expr: AstPtr::new(&match_expr), - arms: AstPtr::new(&arms), - }) - } - } - } - } - - fn validate_match2( - &mut self, - id: ExprId, - match_expr: ExprId, - arms: &[MatchArm], - db: &dyn HirDatabase, - infer: Arc, - ) { - use crate::diagnostics::pattern::usefulness; - use hir_def::HasModule; - - let (body, source_map): (Arc, Arc) = - db.body_with_source_map(self.owner); - - let match_expr_ty = if infer.type_of_expr[match_expr].is_unknown() { - return; - } else { - &infer.type_of_expr[match_expr] - }; - let pattern_arena = RefCell::new(PatternArena::new()); let mut m_arms = Vec::new(); @@ -401,16 +315,17 @@ impl<'a, 'b> ExprValidator<'a, 'b> { // necessary. // // FIXME we should use the type checker for this. - if pat_ty == match_expr_ty + if (pat_ty == match_expr_ty || match_expr_ty .as_reference() .map(|(match_expr_ty, ..)| match_expr_ty == pat_ty) - .unwrap_or(false) + .unwrap_or(false)) + && types_of_subpatterns_do_match(arm.pat, &body, &infer) { // If we had a NotUsefulMatchArm diagnostic, we could // check the usefulness of each pattern as we added it // to the matrix here. - let m_arm = usefulness::MatchArm { + let m_arm = match_check::MatchArm { pat: self.lower_pattern( arm.pat, &mut pattern_arena.borrow_mut(), @@ -434,14 +349,14 @@ impl<'a, 'b> ExprValidator<'a, 'b> { return; } - let cx = usefulness::MatchCheckCtx { + let cx = MatchCheckCtx { module: self.owner.module(db.upcast()), match_expr, infer: &infer, db, pattern_arena: &pattern_arena, }; - let report = usefulness::compute_match_usefulness(&cx, &m_arms); + let report = compute_match_usefulness(&cx, &m_arms); // FIXME Report unreacheble arms // https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/check_match.rs#L200-L201 @@ -473,8 +388,8 @@ impl<'a, 'b> ExprValidator<'a, 'b> { db: &dyn HirDatabase, body: &Body, have_errors: &mut bool, - ) -> pattern::PatId { - let mut patcx = pattern::PatCtxt::new(db, &self.infer, body); + ) -> match_check::PatId { + let mut patcx = match_check::PatCtxt::new(db, &self.infer, body); let pattern = patcx.lower_pattern(pat); let pattern = pattern_arena.alloc(expand_pattern(pattern)); if !patcx.errors.is_empty() { diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index 52e9a5b1b3f7..aebadd391701 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -1,864 +1,340 @@ -//! This module implements match statement exhaustiveness checking and usefulness checking -//! for match arms. +//! Validation of matches. //! -//! It is modeled on the rustc module `librustc_mir_build::hair::pattern::_match`, which -//! contains very detailed documentation about the algorithms used here. I've duplicated -//! most of that documentation below. +//! This module provides lowering from [hir_def::expr::Pat] to [self::Pat] and match +//! checking algorithm. //! -//! This file includes the logic for exhaustiveness and usefulness checking for -//! pattern-matching. Specifically, given a list of patterns for a type, we can -//! tell whether: -//! - (a) the patterns cover every possible constructor for the type (exhaustiveness). -//! - (b) each pattern is necessary (usefulness). -//! -//! The algorithm implemented here is a modified version of the one described in -//! . -//! However, to save future implementors from reading the original paper, we -//! summarize the algorithm here to hopefully save time and be a little clearer -//! (without being so rigorous). -//! -//! The core of the algorithm revolves about a "usefulness" check. In particular, we -//! are trying to compute a predicate `U(P, p)` where `P` is a list of patterns (we refer to this as -//! a matrix). `U(P, p)` represents whether, given an existing list of patterns -//! `P_1 ..= P_m`, adding a new pattern `p` will be "useful" (that is, cover previously- -//! uncovered values of the type). -//! -//! If we have this predicate, then we can easily compute both exhaustiveness of an -//! entire set of patterns and the individual usefulness of each one. -//! (a) the set of patterns is exhaustive iff `U(P, _)` is false (i.e., adding a wildcard -//! match doesn't increase the number of values we're matching) -//! (b) a pattern `P_i` is not useful if `U(P[0..=(i-1), P_i)` is false (i.e., adding a -//! pattern to those that have come before it doesn't increase the number of values -//! we're matching). -//! -//! During the course of the algorithm, the rows of the matrix won't just be individual patterns, -//! but rather partially-deconstructed patterns in the form of a list of patterns. The paper -//! calls those pattern-vectors, and we will call them pattern-stacks. The same holds for the -//! new pattern `p`. -//! -//! For example, say we have the following: -//! -//! ```ignore -//! // x: (Option, Result<()>) -//! match x { -//! (Some(true), _) => (), -//! (None, Err(())) => (), -//! (None, Err(_)) => (), -//! } -//! ``` -//! -//! Here, the matrix `P` starts as: -//! -//! ```text -//! [ -//! [(Some(true), _)], -//! [(None, Err(()))], -//! [(None, Err(_))], -//! ] -//! ``` -//! -//! We can tell it's not exhaustive, because `U(P, _)` is true (we're not covering -//! `[(Some(false), _)]`, for instance). In addition, row 3 is not useful, because -//! all the values it covers are already covered by row 2. -//! -//! A list of patterns can be thought of as a stack, because we are mainly interested in the top of -//! the stack at any given point, and we can pop or apply constructors to get new pattern-stacks. -//! To match the paper, the top of the stack is at the beginning / on the left. -//! -//! There are two important operations on pattern-stacks necessary to understand the algorithm: -//! -//! 1. We can pop a given constructor off the top of a stack. This operation is called -//! `specialize`, and is denoted `S(c, p)` where `c` is a constructor (like `Some` or -//! `None`) and `p` a pattern-stack. -//! If the pattern on top of the stack can cover `c`, this removes the constructor and -//! pushes its arguments onto the stack. It also expands OR-patterns into distinct patterns. -//! Otherwise the pattern-stack is discarded. -//! This essentially filters those pattern-stacks whose top covers the constructor `c` and -//! discards the others. -//! -//! For example, the first pattern above initially gives a stack `[(Some(true), _)]`. If we -//! pop the tuple constructor, we are left with `[Some(true), _]`, and if we then pop the -//! `Some` constructor we get `[true, _]`. If we had popped `None` instead, we would get -//! nothing back. -//! -//! This returns zero or more new pattern-stacks, as follows. We look at the pattern `p_1` -//! on top of the stack, and we have four cases: -//! -//! * 1.1. `p_1 = c(r_1, .., r_a)`, i.e. the top of the stack has constructor `c`. We push onto -//! the stack the arguments of this constructor, and return the result: -//! -//! r_1, .., r_a, p_2, .., p_n -//! -//! * 1.2. `p_1 = c'(r_1, .., r_a')` where `c ≠ c'`. We discard the current stack and return -//! nothing. -//! * 1.3. `p_1 = _`. We push onto the stack as many wildcards as the constructor `c` has -//! arguments (its arity), and return the resulting stack: -//! -//! _, .., _, p_2, .., p_n -//! -//! * 1.4. `p_1 = r_1 | r_2`. We expand the OR-pattern and then recurse on each resulting stack: -//! -//! S(c, (r_1, p_2, .., p_n)) -//! S(c, (r_2, p_2, .., p_n)) -//! -//! 2. We can pop a wildcard off the top of the stack. This is called `D(p)`, where `p` is -//! a pattern-stack. -//! This is used when we know there are missing constructor cases, but there might be -//! existing wildcard patterns, so to check the usefulness of the matrix, we have to check -//! all its *other* components. -//! -//! It is computed as follows. We look at the pattern `p_1` on top of the stack, -//! and we have three cases: -//! * 1.1. `p_1 = c(r_1, .., r_a)`. We discard the current stack and return nothing. -//! * 1.2. `p_1 = _`. We return the rest of the stack: -//! -//! p_2, .., p_n -//! -//! * 1.3. `p_1 = r_1 | r_2`. We expand the OR-pattern and then recurse on each resulting stack: -//! -//! D((r_1, p_2, .., p_n)) -//! D((r_2, p_2, .., p_n)) -//! -//! Note that the OR-patterns are not always used directly in Rust, but are used to derive the -//! exhaustive integer matching rules, so they're written here for posterity. -//! -//! Both those operations extend straightforwardly to a list or pattern-stacks, i.e. a matrix, by -//! working row-by-row. Popping a constructor ends up keeping only the matrix rows that start with -//! the given constructor, and popping a wildcard keeps those rows that start with a wildcard. -//! -//! -//! The algorithm for computing `U` -//! ------------------------------- -//! The algorithm is inductive (on the number of columns: i.e., components of tuple patterns). -//! That means we're going to check the components from left-to-right, so the algorithm -//! operates principally on the first component of the matrix and new pattern-stack `p`. -//! This algorithm is realized in the `is_useful` function. -//! -//! Base case (`n = 0`, i.e., an empty tuple pattern): -//! - If `P` already contains an empty pattern (i.e., if the number of patterns `m > 0`), then -//! `U(P, p)` is false. -//! - Otherwise, `P` must be empty, so `U(P, p)` is true. -//! -//! Inductive step (`n > 0`, i.e., whether there's at least one column [which may then be expanded -//! into further columns later]). We're going to match on the top of the new pattern-stack, `p_1`: -//! -//! - If `p_1 == c(r_1, .., r_a)`, i.e. we have a constructor pattern. -//! Then, the usefulness of `p_1` can be reduced to whether it is useful when -//! we ignore all the patterns in the first column of `P` that involve other constructors. -//! This is where `S(c, P)` comes in: -//! -//! ```text -//! U(P, p) := U(S(c, P), S(c, p)) -//! ``` -//! -//! This special case is handled in `is_useful_specialized`. -//! -//! For example, if `P` is: -//! -//! ```text -//! [ -//! [Some(true), _], -//! [None, 0], -//! ] -//! ``` -//! -//! and `p` is `[Some(false), 0]`, then we don't care about row 2 since we know `p` only -//! matches values that row 2 doesn't. For row 1 however, we need to dig into the -//! arguments of `Some` to know whether some new value is covered. So we compute -//! `U([[true, _]], [false, 0])`. -//! -//! - If `p_1 == _`, then we look at the list of constructors that appear in the first component of -//! the rows of `P`: -//! - If there are some constructors that aren't present, then we might think that the -//! wildcard `_` is useful, since it covers those constructors that weren't covered -//! before. -//! That's almost correct, but only works if there were no wildcards in those first -//! components. So we need to check that `p` is useful with respect to the rows that -//! start with a wildcard, if there are any. This is where `D` comes in: -//! `U(P, p) := U(D(P), D(p))` -//! -//! For example, if `P` is: -//! ```text -//! [ -//! [_, true, _], -//! [None, false, 1], -//! ] -//! ``` -//! and `p` is `[_, false, _]`, the `Some` constructor doesn't appear in `P`. So if we -//! only had row 2, we'd know that `p` is useful. However row 1 starts with a -//! wildcard, so we need to check whether `U([[true, _]], [false, 1])`. -//! -//! - Otherwise, all possible constructors (for the relevant type) are present. In this -//! case we must check whether the wildcard pattern covers any unmatched value. For -//! that, we can think of the `_` pattern as a big OR-pattern that covers all -//! possible constructors. For `Option`, that would mean `_ = None | Some(_)` for -//! example. The wildcard pattern is useful in this case if it is useful when -//! specialized to one of the possible constructors. So we compute: -//! `U(P, p) := ∃(k ϵ constructors) U(S(k, P), S(k, p))` -//! -//! For example, if `P` is: -//! ```text -//! [ -//! [Some(true), _], -//! [None, false], -//! ] -//! ``` -//! and `p` is `[_, false]`, both `None` and `Some` constructors appear in the first -//! components of `P`. We will therefore try popping both constructors in turn: we -//! compute `U([[true, _]], [_, false])` for the `Some` constructor, and `U([[false]], -//! [false])` for the `None` constructor. The first case returns true, so we know that -//! `p` is useful for `P`. Indeed, it matches `[Some(false), _]` that wasn't matched -//! before. -//! -//! - If `p_1 == r_1 | r_2`, then the usefulness depends on each `r_i` separately: -//! -//! ```text -//! U(P, p) := U(P, (r_1, p_2, .., p_n)) -//! || U(P, (r_2, p_2, .., p_n)) -//! ``` -use std::{iter, sync::Arc}; +//! It is modeled on the rustc module `rustc_mir_build::thir::pattern`. -use hir_def::{ - adt::VariantData, - body::Body, - expr::{Expr, Literal, Pat, PatId}, - EnumVariantId, StructId, VariantId, -}; +mod deconstruct_pat; +mod pat_util; +pub(crate) mod usefulness; + +use hir_def::{body::Body, EnumVariantId, LocalFieldId, VariantId}; use la_arena::Idx; -use smallvec::{smallvec, SmallVec}; -use crate::{db::HirDatabase, AdtId, InferenceResult, Interner, TyExt, TyKind}; +use crate::{db::HirDatabase, InferenceResult, Interner, Substitution, Ty, TyKind}; -#[derive(Debug, Clone, Copy)] -/// Either a pattern from the source code being analyzed, represented as -/// as `PatId`, or a `Wild` pattern which is created as an intermediate -/// step in the match checking algorithm and thus is not backed by a -/// real `PatId`. -/// -/// Note that it is totally valid for the `PatId` variant to contain -/// a `PatId` which resolves to a `Wild` pattern, if that wild pattern -/// exists in the source code being analyzed. -enum PatIdOrWild { - PatId(PatId), - Wild, -} +use self::pat_util::EnumerateAndAdjustIterator; -impl PatIdOrWild { - fn as_pat(self, cx: &MatchCheckCtx) -> Pat { - match self { - PatIdOrWild::PatId(id) => cx.body.pats[id].clone(), - PatIdOrWild::Wild => Pat::Wild, - } - } +pub(crate) use self::usefulness::MatchArm; - fn as_id(self) -> Option { - match self { - PatIdOrWild::PatId(id) => Some(id), - PatIdOrWild::Wild => None, - } - } -} +pub(crate) type PatId = Idx; -impl From for PatIdOrWild { - fn from(pat_id: PatId) -> Self { - Self::PatId(pat_id) - } -} - -impl From<&PatId> for PatIdOrWild { - fn from(pat_id: &PatId) -> Self { - Self::PatId(*pat_id) - } -} - -#[derive(Debug, Clone, Copy, PartialEq)] -pub(super) enum MatchCheckErr { - NotImplemented, - MalformedMatchArm, - /// Used when type inference cannot resolve the type of - /// a pattern or expression. - Unknown, -} - -/// The return type of `is_useful` is either an indication of usefulness -/// of the match arm, or an error in the case the match statement -/// is made up of types for which exhaustiveness checking is currently -/// not completely implemented. -/// -/// The `std::result::Result` type is used here rather than a custom enum -/// to allow the use of `?`. -pub(super) type MatchCheckResult = Result; - -#[derive(Debug)] -/// A row in a Matrix. -/// -/// This type is modeled from the struct of the same name in `rustc`. -pub(super) struct PatStack(PatStackInner); -type PatStackInner = SmallVec<[PatIdOrWild; 2]>; - -impl PatStack { - pub(super) fn from_pattern(pat_id: PatId) -> PatStack { - Self(smallvec!(pat_id.into())) - } - - pub(super) fn from_wild() -> PatStack { - Self(smallvec!(PatIdOrWild::Wild)) - } - - fn from_slice(slice: &[PatIdOrWild]) -> PatStack { - Self(SmallVec::from_slice(slice)) - } - - fn from_vec(v: PatStackInner) -> PatStack { - Self(v) - } - - fn get_head(&self) -> Option { - self.0.first().copied() - } - - fn tail(&self) -> &[PatIdOrWild] { - self.0.get(1..).unwrap_or(&[]) - } - - fn to_tail(&self) -> PatStack { - Self::from_slice(self.tail()) - } - - fn replace_head_with(&self, pats: I) -> PatStack - where - I: Iterator, - T: Into, - { - let mut patterns: PatStackInner = smallvec![]; - for pat in pats { - patterns.push(pat.into()); - } - for pat in &self.0[1..] { - patterns.push(*pat); - } - PatStack::from_vec(patterns) - } - - /// Computes `D(self)`. - /// - /// See the module docs and the associated documentation in rustc for details. - fn specialize_wildcard(&self, cx: &MatchCheckCtx) -> Option { - if matches!(self.get_head()?.as_pat(cx), Pat::Wild) { - Some(self.to_tail()) - } else { - None - } - } - - /// Computes `S(constructor, self)`. - /// - /// See the module docs and the associated documentation in rustc for details. - fn specialize_constructor( - &self, - cx: &MatchCheckCtx, - constructor: &Constructor, - ) -> MatchCheckResult> { - let head = match self.get_head() { - Some(head) => head, - None => return Ok(None), - }; - - let head_pat = head.as_pat(cx); - let result = match (head_pat, constructor) { - (Pat::Tuple { args: pat_ids, ellipsis }, &Constructor::Tuple { arity }) => { - if let Some(ellipsis) = ellipsis { - let (pre, post) = pat_ids.split_at(ellipsis); - let n_wild_pats = arity.saturating_sub(pat_ids.len()); - let pre_iter = pre.iter().map(Into::into); - let wildcards = iter::repeat(PatIdOrWild::Wild).take(n_wild_pats); - let post_iter = post.iter().map(Into::into); - Some(self.replace_head_with(pre_iter.chain(wildcards).chain(post_iter))) - } else { - Some(self.replace_head_with(pat_ids.iter())) - } - } - (Pat::Lit(lit_expr), Constructor::Bool(constructor_val)) => { - match cx.body.exprs[lit_expr] { - Expr::Literal(Literal::Bool(pat_val)) if *constructor_val == pat_val => { - Some(self.to_tail()) - } - // it was a bool but the value doesn't match - Expr::Literal(Literal::Bool(_)) => None, - // perhaps this is actually unreachable given we have - // already checked that these match arms have the appropriate type? - _ => return Err(MatchCheckErr::NotImplemented), - } - } - (Pat::Wild, constructor) => Some(self.expand_wildcard(cx, constructor)?), - (Pat::Path(_), constructor) => { - // unit enum variants become `Pat::Path` - let pat_id = head.as_id().expect("we know this isn't a wild"); - let variant_id: VariantId = match constructor { - &Constructor::Enum(e) => e.into(), - &Constructor::Struct(s) => s.into(), - _ => return Err(MatchCheckErr::NotImplemented), - }; - if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) { - None - } else { - Some(self.to_tail()) - } - } - (Pat::TupleStruct { args: ref pat_ids, ellipsis, .. }, constructor) => { - let pat_id = head.as_id().expect("we know this isn't a wild"); - let variant_id: VariantId = match constructor { - &Constructor::Enum(e) => e.into(), - &Constructor::Struct(s) => s.into(), - _ => return Err(MatchCheckErr::MalformedMatchArm), - }; - if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) { - None - } else { - let constructor_arity = constructor.arity(cx)?; - if let Some(ellipsis_position) = ellipsis { - // If there are ellipsis in the pattern, the ellipsis must take the place - // of at least one sub-pattern, so `pat_ids` should be smaller than the - // constructor arity. - if pat_ids.len() < constructor_arity { - let mut new_patterns: Vec = vec![]; - - for pat_id in &pat_ids[0..ellipsis_position] { - new_patterns.push((*pat_id).into()); - } - - for _ in 0..(constructor_arity - pat_ids.len()) { - new_patterns.push(PatIdOrWild::Wild); - } - - for pat_id in &pat_ids[ellipsis_position..pat_ids.len()] { - new_patterns.push((*pat_id).into()); - } - - Some(self.replace_head_with(new_patterns.into_iter())) - } else { - return Err(MatchCheckErr::MalformedMatchArm); - } - } else { - // If there is no ellipsis in the tuple pattern, the number - // of patterns must equal the constructor arity. - if pat_ids.len() == constructor_arity { - Some(self.replace_head_with(pat_ids.into_iter())) - } else { - return Err(MatchCheckErr::MalformedMatchArm); - } - } - } - } - (Pat::Record { args: ref arg_patterns, .. }, constructor) => { - let pat_id = head.as_id().expect("we know this isn't a wild"); - let (variant_id, variant_data) = match constructor { - &Constructor::Enum(e) => ( - e.into(), - cx.db.enum_data(e.parent).variants[e.local_id].variant_data.clone(), - ), - &Constructor::Struct(s) => { - (s.into(), cx.db.struct_data(s).variant_data.clone()) - } - _ => return Err(MatchCheckErr::MalformedMatchArm), - }; - if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) { - None - } else { - match variant_data.as_ref() { - VariantData::Record(struct_field_arena) => { - // Here we treat any missing fields in the record as the wild pattern, as - // if the record has ellipsis. We want to do this here even if the - // record does not contain ellipsis, because it allows us to continue - // enforcing exhaustiveness for the rest of the match statement. - // - // Creating the diagnostic for the missing field in the pattern - // should be done in a different diagnostic. - let patterns = struct_field_arena.iter().map(|(_, struct_field)| { - arg_patterns - .iter() - .find(|pat| pat.name == struct_field.name) - .map(|pat| PatIdOrWild::from(pat.pat)) - .unwrap_or(PatIdOrWild::Wild) - }); - - Some(self.replace_head_with(patterns)) - } - _ => return Err(MatchCheckErr::Unknown), - } - } - } - (Pat::Or(_), _) => return Err(MatchCheckErr::NotImplemented), - (_, _) => return Err(MatchCheckErr::NotImplemented), - }; - - Ok(result) - } - - /// A special case of `specialize_constructor` where the head of the pattern stack - /// is a Wild pattern. - /// - /// Replaces the Wild pattern at the head of the pattern stack with N Wild patterns - /// (N >= 0), where N is the arity of the given constructor. - fn expand_wildcard( - &self, - cx: &MatchCheckCtx, - constructor: &Constructor, - ) -> MatchCheckResult { - assert_eq!( - Pat::Wild, - self.get_head().expect("expand_wildcard called on empty PatStack").as_pat(cx), - "expand_wildcard must only be called on PatStack with wild at head", - ); - - let mut patterns: PatStackInner = smallvec![]; - - for _ in 0..constructor.arity(cx)? { - patterns.push(PatIdOrWild::Wild); - } - - for pat in &self.0[1..] { - patterns.push(*pat); - } - - Ok(PatStack::from_vec(patterns)) - } -} - -/// A collection of PatStack. -/// -/// This type is modeled from the struct of the same name in `rustc`. -pub(super) struct Matrix(Vec); - -impl Matrix { - pub(super) fn empty() -> Self { - Self(vec![]) - } - - pub(super) fn push(&mut self, cx: &MatchCheckCtx, row: PatStack) { - if let Some(Pat::Or(pat_ids)) = row.get_head().map(|pat_id| pat_id.as_pat(cx)) { - // Or patterns are expanded here - for pat_id in pat_ids { - self.0.push(row.replace_head_with([pat_id].iter())); - } - } else { - self.0.push(row); - } - } - - fn is_empty(&self) -> bool { - self.0.is_empty() - } - - fn heads(&self) -> Vec { - self.0.iter().flat_map(|p| p.get_head()).collect() - } - - /// Computes `D(self)` for each contained PatStack. - /// - /// See the module docs and the associated documentation in rustc for details. - fn specialize_wildcard(&self, cx: &MatchCheckCtx) -> Self { - Self::collect(cx, self.0.iter().filter_map(|r| r.specialize_wildcard(cx))) - } - - /// Computes `S(constructor, self)` for each contained PatStack. - /// - /// See the module docs and the associated documentation in rustc for details. - fn specialize_constructor( - &self, - cx: &MatchCheckCtx, - constructor: &Constructor, - ) -> MatchCheckResult { - let mut new_matrix = Matrix::empty(); - for pat in &self.0 { - if let Some(pat) = pat.specialize_constructor(cx, constructor)? { - new_matrix.push(cx, pat); - } - } - - Ok(new_matrix) - } - - fn collect>(cx: &MatchCheckCtx, iter: T) -> Self { - let mut matrix = Matrix::empty(); - - for pat in iter { - // using push ensures we expand or-patterns - matrix.push(cx, pat); - } - - matrix - } +#[derive(Clone, Debug)] +pub(crate) enum PatternError { + Unimplemented, + UnresolvedVariant, } #[derive(Clone, Debug, PartialEq)] -/// An indication of the usefulness of a given match arm, where -/// usefulness is defined as matching some patterns which were -/// not matched by an prior match arms. -/// -/// We may eventually need an `Unknown` variant here. -pub(super) enum Usefulness { - Useful, - NotUseful, +pub(crate) struct FieldPat { + pub(crate) field: LocalFieldId, + pub(crate) pattern: Pat, } -pub(super) struct MatchCheckCtx<'a> { - pub(super) match_expr: Idx, - pub(super) body: Arc, - pub(super) infer: Arc, - pub(super) db: &'a dyn HirDatabase, +#[derive(Clone, Debug, PartialEq)] +pub(crate) struct Pat { + pub(crate) ty: Ty, + pub(crate) kind: Box, } -/// Given a set of patterns `matrix`, and pattern to consider `v`, determines -/// whether `v` is useful. A pattern is useful if it covers cases which were -/// not previously covered. -/// -/// When calling this function externally (that is, not the recursive calls) it -/// expected that you have already type checked the match arms. All patterns in -/// matrix should be the same type as v, as well as they should all be the same -/// type as the match expression. -pub(super) fn is_useful( - cx: &MatchCheckCtx, - matrix: &Matrix, - v: &PatStack, -) -> MatchCheckResult { - // Handle two special cases: - // - enum with no variants - // - `!` type - // In those cases, no match arm is useful. - match cx.infer[cx.match_expr].strip_references().kind(&Interner) { - TyKind::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ..) => { - if cx.db.enum_data(*enum_id).variants.is_empty() { - return Ok(Usefulness::NotUseful); - } - } - TyKind::Never => return Ok(Usefulness::NotUseful), - _ => (), +impl Pat { + pub(crate) fn wildcard_from_ty(ty: &Ty) -> Self { + Pat { ty: ty.clone(), kind: Box::new(PatKind::Wild) } + } +} + +/// Close relative to `rustc_mir_build::thir::pattern::PatKind` +#[derive(Clone, Debug, PartialEq)] +pub(crate) enum PatKind { + Wild, + + /// `x`, `ref x`, `x @ P`, etc. + Binding { + subpattern: Option, + }, + + /// `Foo(...)` or `Foo{...}` or `Foo`, where `Foo` is a variant name from an ADT with + /// multiple variants. + Variant { + substs: Substitution, + enum_variant: EnumVariantId, + subpatterns: Vec, + }, + + /// `(...)`, `Foo(...)`, `Foo{...}`, or `Foo`, where `Foo` is a variant name from an ADT with + /// a single variant. + Leaf { + subpatterns: Vec, + }, + + /// `box P`, `&P`, `&mut P`, etc. + Deref { + subpattern: Pat, + }, + + // FIXME: for now, only bool literals are implemented + LiteralBool { + value: bool, + }, + + /// An or-pattern, e.g. `p | q`. + /// Invariant: `pats.len() >= 2`. + Or { + pats: Vec, + }, +} + +pub(crate) struct PatCtxt<'a> { + db: &'a dyn HirDatabase, + infer: &'a InferenceResult, + body: &'a Body, + pub(crate) errors: Vec, +} + +impl<'a> PatCtxt<'a> { + pub(crate) fn new(db: &'a dyn HirDatabase, infer: &'a InferenceResult, body: &'a Body) -> Self { + Self { db, infer, body, errors: Vec::new() } } - let head = match v.get_head() { - Some(head) => head, - None => { - let result = if matrix.is_empty() { Usefulness::Useful } else { Usefulness::NotUseful }; - - return Ok(result); - } - }; - - if let Pat::Or(pat_ids) = head.as_pat(cx) { - let mut found_unimplemented = false; - let any_useful = pat_ids.iter().any(|&pat_id| { - let v = PatStack::from_pattern(pat_id); - - match is_useful(cx, matrix, &v) { - Ok(Usefulness::Useful) => true, - Ok(Usefulness::NotUseful) => false, - _ => { - found_unimplemented = true; - false - } - } - }); - - return if any_useful { - Ok(Usefulness::Useful) - } else if found_unimplemented { - Err(MatchCheckErr::NotImplemented) - } else { - Ok(Usefulness::NotUseful) - }; + pub(crate) fn lower_pattern(&mut self, pat: hir_def::expr::PatId) -> Pat { + // FIXME: implement pattern adjustments (implicit pattern dereference; "RFC 2005-match-ergonomics") + // More info https://github.com/rust-lang/rust/issues/42640#issuecomment-313535089 + let unadjusted_pat = self.lower_pattern_unadjusted(pat); + unadjusted_pat } - if let Some(constructor) = pat_constructor(cx, head)? { - let matrix = matrix.specialize_constructor(&cx, &constructor)?; - let v = v - .specialize_constructor(&cx, &constructor)? - .expect("we know this can't fail because we get the constructor from `v.head()` above"); + fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat { + let ty = &self.infer[pat]; + let variant = self.infer.variant_resolution_for_pat(pat); - is_useful(&cx, &matrix, &v) - } else { - // expanding wildcard - let mut used_constructors: Vec = vec![]; - for pat in matrix.heads() { - if let Some(constructor) = pat_constructor(cx, pat)? { - used_constructors.push(constructor); + let kind = match self.body[pat] { + hir_def::expr::Pat::Wild => PatKind::Wild, + + hir_def::expr::Pat::Lit(expr) => self.lower_lit(expr), + + hir_def::expr::Pat::Path(ref path) => { + return self.lower_path(pat, path); } - } - // We assume here that the first constructor is the "correct" type. Since we - // only care about the "type" of the constructor (i.e. if it is a bool we - // don't care about the value), this assumption should be valid as long as - // the match statement is well formed. We currently uphold this invariant by - // filtering match arms before calling `is_useful`, only passing in match arms - // whose type matches the type of the match expression. - match &used_constructors.first() { - Some(constructor) if all_constructors_covered(&cx, constructor, &used_constructors) => { - // If all constructors are covered, then we need to consider whether - // any values are covered by this wildcard. - // - // For example, with matrix '[[Some(true)], [None]]', all - // constructors are covered (`Some`/`None`), so we need - // to perform specialization to see that our wildcard will cover - // the `Some(false)` case. - // - // Here we create a constructor for each variant and then check - // usefulness after specializing for that constructor. - let mut found_unimplemented = false; - for constructor in constructor.all_constructors(cx) { - let matrix = matrix.specialize_constructor(&cx, &constructor)?; - let v = v.expand_wildcard(&cx, &constructor)?; - - match is_useful(&cx, &matrix, &v) { - Ok(Usefulness::Useful) => return Ok(Usefulness::Useful), - Ok(Usefulness::NotUseful) => continue, - _ => found_unimplemented = true, - }; - } - - if found_unimplemented { - Err(MatchCheckErr::NotImplemented) - } else { - Ok(Usefulness::NotUseful) - } + hir_def::expr::Pat::Tuple { ref args, ellipsis } => { + let arity = match *ty.kind(&Interner) { + TyKind::Tuple(arity, _) => arity, + _ => panic!("unexpected type for tuple pattern: {:?}", ty), + }; + let subpatterns = self.lower_tuple_subpats(args, arity, ellipsis); + PatKind::Leaf { subpatterns } } + + hir_def::expr::Pat::Bind { subpat, .. } => { + PatKind::Binding { subpattern: self.lower_opt_pattern(subpat) } + } + + hir_def::expr::Pat::TupleStruct { ref args, ellipsis, .. } if variant.is_some() => { + let expected_len = variant.unwrap().variant_data(self.db.upcast()).fields().len(); + let subpatterns = self.lower_tuple_subpats(args, expected_len, ellipsis); + self.lower_variant_or_leaf(pat, ty, subpatterns) + } + + hir_def::expr::Pat::Record { ref args, .. } if variant.is_some() => { + let variant_data = variant.unwrap().variant_data(self.db.upcast()); + let subpatterns = args + .iter() + .map(|field| FieldPat { + // XXX(iDawer): field lookup is inefficient + field: variant_data.field(&field.name).unwrap(), + pattern: self.lower_pattern(field.pat), + }) + .collect(); + self.lower_variant_or_leaf(pat, ty, subpatterns) + } + hir_def::expr::Pat::TupleStruct { .. } | hir_def::expr::Pat::Record { .. } => { + self.errors.push(PatternError::UnresolvedVariant); + PatKind::Wild + } + + hir_def::expr::Pat::Or(ref pats) => PatKind::Or { pats: self.lower_patterns(pats) }, + _ => { - // Either not all constructors are covered, or the only other arms - // are wildcards. Either way, this pattern is useful if it is useful - // when compared to those arms with wildcards. - let matrix = matrix.specialize_wildcard(&cx); - let v = v.to_tail(); - - is_useful(&cx, &matrix, &v) + self.errors.push(PatternError::Unimplemented); + PatKind::Wild } - } - } -} - -#[derive(Debug, Clone, Copy)] -/// Similar to TypeCtor, but includes additional information about the specific -/// value being instantiated. For example, TypeCtor::Bool doesn't contain the -/// boolean value. -enum Constructor { - Bool(bool), - Tuple { arity: usize }, - Enum(EnumVariantId), - Struct(StructId), -} - -impl Constructor { - fn arity(&self, cx: &MatchCheckCtx) -> MatchCheckResult { - let arity = match self { - Constructor::Bool(_) => 0, - Constructor::Tuple { arity } => *arity, - Constructor::Enum(e) => { - match cx.db.enum_data(e.parent).variants[e.local_id].variant_data.as_ref() { - VariantData::Tuple(struct_field_data) => struct_field_data.len(), - VariantData::Record(struct_field_data) => struct_field_data.len(), - VariantData::Unit => 0, - } - } - &Constructor::Struct(s) => match cx.db.struct_data(s).variant_data.as_ref() { - VariantData::Tuple(struct_field_data) => struct_field_data.len(), - VariantData::Record(struct_field_data) => struct_field_data.len(), - VariantData::Unit => 0, - }, }; - Ok(arity) + Pat { ty: ty.clone(), kind: Box::new(kind) } } - fn all_constructors(&self, cx: &MatchCheckCtx) -> Vec { + fn lower_tuple_subpats( + &mut self, + pats: &[hir_def::expr::PatId], + expected_len: usize, + ellipsis: Option, + ) -> Vec { + pats.iter() + .enumerate_and_adjust(expected_len, ellipsis) + .map(|(i, &subpattern)| FieldPat { + field: LocalFieldId::from_raw((i as u32).into()), + pattern: self.lower_pattern(subpattern), + }) + .collect() + } + + fn lower_patterns(&mut self, pats: &[hir_def::expr::PatId]) -> Vec { + pats.iter().map(|&p| self.lower_pattern(p)).collect() + } + + fn lower_opt_pattern(&mut self, pat: Option) -> Option { + pat.map(|p| self.lower_pattern(p)) + } + + fn lower_variant_or_leaf( + &mut self, + pat: hir_def::expr::PatId, + ty: &Ty, + subpatterns: Vec, + ) -> PatKind { + let kind = match self.infer.variant_resolution_for_pat(pat) { + Some(variant_id) => { + if let VariantId::EnumVariantId(enum_variant) = variant_id { + let substs = match ty.kind(&Interner) { + TyKind::Adt(_, substs) | TyKind::FnDef(_, substs) => substs.clone(), + TyKind::Error => { + return PatKind::Wild; + } + _ => panic!("inappropriate type for def: {:?}", ty), + }; + PatKind::Variant { substs, enum_variant, subpatterns } + } else { + PatKind::Leaf { subpatterns } + } + } + None => { + self.errors.push(PatternError::UnresolvedVariant); + PatKind::Wild + } + }; + kind + } + + fn lower_path(&mut self, pat: hir_def::expr::PatId, _path: &hir_def::path::Path) -> Pat { + let ty = &self.infer[pat]; + + let pat_from_kind = |kind| Pat { ty: ty.clone(), kind: Box::new(kind) }; + + match self.infer.variant_resolution_for_pat(pat) { + Some(_) => pat_from_kind(self.lower_variant_or_leaf(pat, ty, Vec::new())), + None => { + self.errors.push(PatternError::UnresolvedVariant); + pat_from_kind(PatKind::Wild) + } + } + } + + fn lower_lit(&mut self, expr: hir_def::expr::ExprId) -> PatKind { + use hir_def::expr::{Expr, Literal::Bool}; + + match self.body[expr] { + Expr::Literal(Bool(value)) => PatKind::LiteralBool { value }, + _ => { + self.errors.push(PatternError::Unimplemented); + PatKind::Wild + } + } + } +} + +pub(crate) trait PatternFoldable: Sized { + fn fold_with(&self, folder: &mut F) -> Self { + self.super_fold_with(folder) + } + + fn super_fold_with(&self, folder: &mut F) -> Self; +} + +pub(crate) trait PatternFolder: Sized { + fn fold_pattern(&mut self, pattern: &Pat) -> Pat { + pattern.super_fold_with(self) + } + + fn fold_pattern_kind(&mut self, kind: &PatKind) -> PatKind { + kind.super_fold_with(self) + } +} + +impl PatternFoldable for Box { + fn super_fold_with(&self, folder: &mut F) -> Self { + let content: T = (**self).fold_with(folder); + Box::new(content) + } +} + +impl PatternFoldable for Vec { + fn super_fold_with(&self, folder: &mut F) -> Self { + self.iter().map(|t| t.fold_with(folder)).collect() + } +} + +impl PatternFoldable for Option { + fn super_fold_with(&self, folder: &mut F) -> Self { + self.as_ref().map(|t| t.fold_with(folder)) + } +} + +macro_rules! clone_impls { + ($($ty:ty),+) => { + $( + impl PatternFoldable for $ty { + fn super_fold_with(&self, _: &mut F) -> Self { + Clone::clone(self) + } + } + )+ + } +} + +clone_impls! { LocalFieldId, Ty, Substitution, EnumVariantId } + +impl PatternFoldable for FieldPat { + fn super_fold_with(&self, folder: &mut F) -> Self { + FieldPat { field: self.field.fold_with(folder), pattern: self.pattern.fold_with(folder) } + } +} + +impl PatternFoldable for Pat { + fn fold_with(&self, folder: &mut F) -> Self { + folder.fold_pattern(self) + } + + fn super_fold_with(&self, folder: &mut F) -> Self { + Pat { ty: self.ty.fold_with(folder), kind: self.kind.fold_with(folder) } + } +} + +impl PatternFoldable for PatKind { + fn fold_with(&self, folder: &mut F) -> Self { + folder.fold_pattern_kind(self) + } + + fn super_fold_with(&self, folder: &mut F) -> Self { match self { - Constructor::Bool(_) => vec![Constructor::Bool(true), Constructor::Bool(false)], - Constructor::Tuple { .. } | Constructor::Struct(_) => vec![*self], - Constructor::Enum(e) => cx - .db - .enum_data(e.parent) - .variants - .iter() - .map(|(local_id, _)| { - Constructor::Enum(EnumVariantId { parent: e.parent, local_id }) - }) - .collect(), - } - } -} - -/// Returns the constructor for the given pattern. Should only return None -/// in the case of a Wild pattern. -fn pat_constructor(cx: &MatchCheckCtx, pat: PatIdOrWild) -> MatchCheckResult> { - let res = match pat.as_pat(cx) { - Pat::Wild => None, - Pat::Tuple { .. } => { - let pat_id = pat.as_id().expect("we already know this pattern is not a wild"); - Some(Constructor::Tuple { - arity: cx.infer.type_of_pat[pat_id] - .as_tuple() - .ok_or(MatchCheckErr::Unknown)? - .len(&Interner), - }) - } - Pat::Lit(lit_expr) => match cx.body.exprs[lit_expr] { - Expr::Literal(Literal::Bool(val)) => Some(Constructor::Bool(val)), - _ => return Err(MatchCheckErr::NotImplemented), - }, - Pat::TupleStruct { .. } | Pat::Path(_) | Pat::Record { .. } => { - let pat_id = pat.as_id().expect("we already know this pattern is not a wild"); - let variant_id = - cx.infer.variant_resolution_for_pat(pat_id).ok_or(MatchCheckErr::Unknown)?; - match variant_id { - VariantId::EnumVariantId(enum_variant_id) => { - Some(Constructor::Enum(enum_variant_id)) - } - VariantId::StructId(struct_id) => Some(Constructor::Struct(struct_id)), - _ => return Err(MatchCheckErr::NotImplemented), + PatKind::Wild => PatKind::Wild, + PatKind::Binding { subpattern } => { + PatKind::Binding { subpattern: subpattern.fold_with(folder) } } - } - _ => return Err(MatchCheckErr::NotImplemented), - }; - - Ok(res) -} - -fn all_constructors_covered( - cx: &MatchCheckCtx, - constructor: &Constructor, - used_constructors: &[Constructor], -) -> bool { - match constructor { - Constructor::Tuple { arity } => { - used_constructors.iter().any(|constructor| match constructor { - Constructor::Tuple { arity: used_arity } => arity == used_arity, - _ => false, - }) - } - Constructor::Bool(_) => { - if used_constructors.is_empty() { - return false; + PatKind::Variant { substs, enum_variant, subpatterns } => PatKind::Variant { + substs: substs.fold_with(folder), + enum_variant: enum_variant.fold_with(folder), + subpatterns: subpatterns.fold_with(folder), + }, + PatKind::Leaf { subpatterns } => { + PatKind::Leaf { subpatterns: subpatterns.fold_with(folder) } } - - let covers_true = - used_constructors.iter().any(|c| matches!(c, Constructor::Bool(true))); - let covers_false = - used_constructors.iter().any(|c| matches!(c, Constructor::Bool(false))); - - covers_true && covers_false - } - Constructor::Enum(e) => cx.db.enum_data(e.parent).variants.iter().all(|(id, _)| { - for constructor in used_constructors { - if let Constructor::Enum(e) = constructor { - if id == e.local_id { - return true; - } - } + PatKind::Deref { subpattern } => { + PatKind::Deref { subpattern: subpattern.fold_with(folder) } } - - false - }), - &Constructor::Struct(s) => used_constructors.iter().any(|constructor| match constructor { - &Constructor::Struct(sid) => sid == s, - _ => false, - }), + &PatKind::LiteralBool { value } => PatKind::LiteralBool { value }, + PatKind::Or { pats } => PatKind::Or { pats: pats.fold_with(folder) }, + } } } @@ -1514,6 +990,41 @@ fn main() { "#, ); } + + #[test] + fn no_panic_at_unimplemented_subpattern_type() { + check_diagnostics( + r#" +struct S { a: char} +fn main(v: S) { + match v { S{ a } => {} } + match v { S{ a: _x } => {} } + match v { S{ a: 'a' } => {} } + match v { S{..} => {} } + match v { _ => {} } + match v { } + //^ Missing match arm +} +"#, + ); + } + + #[test] + fn binding() { + check_diagnostics( + r#" +fn main() { + match true { + _x @ true => {} + false => {} + } + match true { _x @ true => {} } + //^^^^ Missing match arm +} +"#, + ); + } + mod false_negatives { //! The implementation of match checking here is a work in progress. As we roll this out, we //! prefer false negatives to false positives (ideally there would be no false positives). This diff --git a/crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs similarity index 100% rename from crates/hir_ty/src/diagnostics/pattern/deconstruct_pat.rs rename to crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs diff --git a/crates/hir_ty/src/diagnostics/pattern/pat_util.rs b/crates/hir_ty/src/diagnostics/match_check/pat_util.rs similarity index 100% rename from crates/hir_ty/src/diagnostics/pattern/pat_util.rs rename to crates/hir_ty/src/diagnostics/match_check/pat_util.rs diff --git a/crates/hir_ty/src/diagnostics/pattern/usefulness.rs b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs similarity index 100% rename from crates/hir_ty/src/diagnostics/pattern/usefulness.rs rename to crates/hir_ty/src/diagnostics/match_check/usefulness.rs diff --git a/crates/hir_ty/src/diagnostics/pattern.rs b/crates/hir_ty/src/diagnostics/pattern.rs deleted file mode 100644 index f8d2e9baa99f..000000000000 --- a/crates/hir_ty/src/diagnostics/pattern.rs +++ /dev/null @@ -1,1040 +0,0 @@ -//! Validation of matches. -//! -//! This module provides lowering from [hir_def::expr::Pat] to [self::Pat] and match -//! checking algorithm. -//! -//! It is modeled on the rustc module `rustc_mir_build::thir::pattern`. - -mod deconstruct_pat; -mod pat_util; -pub(crate) mod usefulness; - -use hir_def::{body::Body, EnumVariantId, LocalFieldId, VariantId}; -use la_arena::Idx; - -use crate::{db::HirDatabase, InferenceResult, Interner, Substitution, Ty, TyKind}; - -use self::pat_util::EnumerateAndAdjustIterator; - -pub(crate) type PatId = Idx; - -#[derive(Clone, Debug)] -pub(crate) enum PatternError { - Unimplemented, - UnresolvedVariant, -} - -#[derive(Clone, Debug, PartialEq)] -pub(crate) struct FieldPat { - pub(crate) field: LocalFieldId, - pub(crate) pattern: Pat, -} - -#[derive(Clone, Debug, PartialEq)] -pub(crate) struct Pat { - pub(crate) ty: Ty, - pub(crate) kind: Box, -} - -impl Pat { - pub(crate) fn wildcard_from_ty(ty: &Ty) -> Self { - Pat { ty: ty.clone(), kind: Box::new(PatKind::Wild) } - } -} - -/// Close relative to `rustc_mir_build::thir::pattern::PatKind` -#[derive(Clone, Debug, PartialEq)] -pub(crate) enum PatKind { - Wild, - - /// `x`, `ref x`, `x @ P`, etc. - Binding { - subpattern: Option, - }, - - /// `Foo(...)` or `Foo{...}` or `Foo`, where `Foo` is a variant name from an ADT with - /// multiple variants. - Variant { - substs: Substitution, - enum_variant: EnumVariantId, - subpatterns: Vec, - }, - - /// `(...)`, `Foo(...)`, `Foo{...}`, or `Foo`, where `Foo` is a variant name from an ADT with - /// a single variant. - Leaf { - subpatterns: Vec, - }, - - /// `box P`, `&P`, `&mut P`, etc. - Deref { - subpattern: Pat, - }, - - // FIXME: for now, only bool literals are implemented - LiteralBool { - value: bool, - }, - - /// An or-pattern, e.g. `p | q`. - /// Invariant: `pats.len() >= 2`. - Or { - pats: Vec, - }, -} - -pub(crate) struct PatCtxt<'a> { - db: &'a dyn HirDatabase, - infer: &'a InferenceResult, - body: &'a Body, - pub(crate) errors: Vec, -} - -impl<'a> PatCtxt<'a> { - pub(crate) fn new(db: &'a dyn HirDatabase, infer: &'a InferenceResult, body: &'a Body) -> Self { - Self { db, infer, body, errors: Vec::new() } - } - - pub(crate) fn lower_pattern(&mut self, pat: hir_def::expr::PatId) -> Pat { - // FIXME: implement pattern adjustments (implicit pattern dereference; "RFC 2005-match-ergonomics") - // More info https://github.com/rust-lang/rust/issues/42640#issuecomment-313535089 - let unadjusted_pat = self.lower_pattern_unadjusted(pat); - unadjusted_pat - } - - fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat { - let ty = &self.infer[pat]; - let variant = self.infer.variant_resolution_for_pat(pat); - - let kind = match self.body[pat] { - hir_def::expr::Pat::Wild => PatKind::Wild, - - hir_def::expr::Pat::Lit(expr) => self.lower_lit(expr), - - hir_def::expr::Pat::Path(ref path) => { - return self.lower_path(pat, path); - } - - hir_def::expr::Pat::Tuple { ref args, ellipsis } => { - let arity = match *ty.kind(&Interner) { - TyKind::Tuple(arity, _) => arity, - _ => panic!("unexpected type for tuple pattern: {:?}", ty), - }; - let subpatterns = self.lower_tuple_subpats(args, arity, ellipsis); - PatKind::Leaf { subpatterns } - } - - hir_def::expr::Pat::Bind { subpat, .. } => { - PatKind::Binding { subpattern: self.lower_opt_pattern(subpat) } - } - - hir_def::expr::Pat::TupleStruct { ref args, ellipsis, .. } if variant.is_some() => { - let expected_len = variant.unwrap().variant_data(self.db.upcast()).fields().len(); - let subpatterns = self.lower_tuple_subpats(args, expected_len, ellipsis); - self.lower_variant_or_leaf(pat, ty, subpatterns) - } - - hir_def::expr::Pat::Record { ref args, .. } if variant.is_some() => { - let variant_data = variant.unwrap().variant_data(self.db.upcast()); - let subpatterns = args - .iter() - .map(|field| FieldPat { - // XXX(iDawer): field lookup is inefficient - field: variant_data.field(&field.name).unwrap(), - pattern: self.lower_pattern(field.pat), - }) - .collect(); - self.lower_variant_or_leaf(pat, ty, subpatterns) - } - hir_def::expr::Pat::TupleStruct { .. } | hir_def::expr::Pat::Record { .. } => { - self.errors.push(PatternError::UnresolvedVariant); - PatKind::Wild - } - - hir_def::expr::Pat::Or(ref pats) => PatKind::Or { pats: self.lower_patterns(pats) }, - - _ => { - self.errors.push(PatternError::Unimplemented); - PatKind::Wild - } - }; - - Pat { ty: ty.clone(), kind: Box::new(kind) } - } - - fn lower_tuple_subpats( - &mut self, - pats: &[hir_def::expr::PatId], - expected_len: usize, - ellipsis: Option, - ) -> Vec { - pats.iter() - .enumerate_and_adjust(expected_len, ellipsis) - .map(|(i, &subpattern)| FieldPat { - field: LocalFieldId::from_raw((i as u32).into()), - pattern: self.lower_pattern(subpattern), - }) - .collect() - } - - fn lower_patterns(&mut self, pats: &[hir_def::expr::PatId]) -> Vec { - pats.iter().map(|&p| self.lower_pattern(p)).collect() - } - - fn lower_opt_pattern(&mut self, pat: Option) -> Option { - pat.map(|p| self.lower_pattern(p)) - } - - fn lower_variant_or_leaf( - &mut self, - pat: hir_def::expr::PatId, - ty: &Ty, - subpatterns: Vec, - ) -> PatKind { - let kind = match self.infer.variant_resolution_for_pat(pat) { - Some(variant_id) => { - if let VariantId::EnumVariantId(enum_variant) = variant_id { - let substs = match ty.kind(&Interner) { - TyKind::Adt(_, substs) | TyKind::FnDef(_, substs) => substs.clone(), - TyKind::Error => { - return PatKind::Wild; - } - _ => panic!("inappropriate type for def: {:?}", ty), - }; - PatKind::Variant { substs, enum_variant, subpatterns } - } else { - PatKind::Leaf { subpatterns } - } - } - None => { - self.errors.push(PatternError::UnresolvedVariant); - PatKind::Wild - } - }; - kind - } - - fn lower_path(&mut self, pat: hir_def::expr::PatId, _path: &hir_def::path::Path) -> Pat { - let ty = &self.infer[pat]; - - let pat_from_kind = |kind| Pat { ty: ty.clone(), kind: Box::new(kind) }; - - match self.infer.variant_resolution_for_pat(pat) { - Some(_) => pat_from_kind(self.lower_variant_or_leaf(pat, ty, Vec::new())), - None => { - self.errors.push(PatternError::UnresolvedVariant); - pat_from_kind(PatKind::Wild) - } - } - } - - fn lower_lit(&mut self, expr: hir_def::expr::ExprId) -> PatKind { - use hir_def::expr::{Expr, Literal::Bool}; - - match self.body[expr] { - Expr::Literal(Bool(value)) => PatKind::LiteralBool { value }, - _ => { - self.errors.push(PatternError::Unimplemented); - PatKind::Wild - } - } - } -} - -pub(crate) trait PatternFoldable: Sized { - fn fold_with(&self, folder: &mut F) -> Self { - self.super_fold_with(folder) - } - - fn super_fold_with(&self, folder: &mut F) -> Self; -} - -pub(crate) trait PatternFolder: Sized { - fn fold_pattern(&mut self, pattern: &Pat) -> Pat { - pattern.super_fold_with(self) - } - - fn fold_pattern_kind(&mut self, kind: &PatKind) -> PatKind { - kind.super_fold_with(self) - } -} - -impl PatternFoldable for Box { - fn super_fold_with(&self, folder: &mut F) -> Self { - let content: T = (**self).fold_with(folder); - Box::new(content) - } -} - -impl PatternFoldable for Vec { - fn super_fold_with(&self, folder: &mut F) -> Self { - self.iter().map(|t| t.fold_with(folder)).collect() - } -} - -impl PatternFoldable for Option { - fn super_fold_with(&self, folder: &mut F) -> Self { - self.as_ref().map(|t| t.fold_with(folder)) - } -} - -macro_rules! clone_impls { - ($($ty:ty),+) => { - $( - impl PatternFoldable for $ty { - fn super_fold_with(&self, _: &mut F) -> Self { - Clone::clone(self) - } - } - )+ - } -} - -clone_impls! { LocalFieldId, Ty, Substitution, EnumVariantId } - -impl PatternFoldable for FieldPat { - fn super_fold_with(&self, folder: &mut F) -> Self { - FieldPat { field: self.field.fold_with(folder), pattern: self.pattern.fold_with(folder) } - } -} - -impl PatternFoldable for Pat { - fn fold_with(&self, folder: &mut F) -> Self { - folder.fold_pattern(self) - } - - fn super_fold_with(&self, folder: &mut F) -> Self { - Pat { ty: self.ty.fold_with(folder), kind: self.kind.fold_with(folder) } - } -} - -impl PatternFoldable for PatKind { - fn fold_with(&self, folder: &mut F) -> Self { - folder.fold_pattern_kind(self) - } - - fn super_fold_with(&self, folder: &mut F) -> Self { - match self { - PatKind::Wild => PatKind::Wild, - PatKind::Binding { subpattern } => { - PatKind::Binding { subpattern: subpattern.fold_with(folder) } - } - PatKind::Variant { substs, enum_variant, subpatterns } => PatKind::Variant { - substs: substs.fold_with(folder), - enum_variant: enum_variant.fold_with(folder), - subpatterns: subpatterns.fold_with(folder), - }, - PatKind::Leaf { subpatterns } => { - PatKind::Leaf { subpatterns: subpatterns.fold_with(folder) } - } - PatKind::Deref { subpattern } => { - PatKind::Deref { subpattern: subpattern.fold_with(folder) } - } - &PatKind::LiteralBool { value } => PatKind::LiteralBool { value }, - PatKind::Or { pats } => PatKind::Or { pats: pats.fold_with(folder) }, - } - } -} - -#[cfg(test)] -mod tests { - use crate::diagnostics::tests::check_diagnostics; - - #[test] - fn empty_tuple() { - check_diagnostics( - r#" -fn main() { - match () { } - //^^ Missing match arm - match (()) { } - //^^^^ Missing match arm - - match () { _ => (), } - match () { () => (), } - match (()) { (()) => (), } -} -"#, - ); - } - - #[test] - fn tuple_of_two_empty_tuple() { - check_diagnostics( - r#" -fn main() { - match ((), ()) { } - //^^^^^^^^ Missing match arm - - match ((), ()) { ((), ()) => (), } -} -"#, - ); - } - - #[test] - fn boolean() { - check_diagnostics( - r#" -fn test_main() { - match false { } - //^^^^^ Missing match arm - match false { true => (), } - //^^^^^ Missing match arm - match (false, true) {} - //^^^^^^^^^^^^^ Missing match arm - match (false, true) { (true, true) => (), } - //^^^^^^^^^^^^^ Missing match arm - match (false, true) { - //^^^^^^^^^^^^^ Missing match arm - (false, true) => (), - (false, false) => (), - (true, false) => (), - } - match (false, true) { (true, _x) => (), } - //^^^^^^^^^^^^^ Missing match arm - - match false { true => (), false => (), } - match (false, true) { - (false, _) => (), - (true, false) => (), - (_, true) => (), - } - match (false, true) { - (true, true) => (), - (true, false) => (), - (false, true) => (), - (false, false) => (), - } - match (false, true) { - (true, _x) => (), - (false, true) => (), - (false, false) => (), - } - match (false, true, false) { - (false, ..) => (), - (true, ..) => (), - } - match (false, true, false) { - (.., false) => (), - (.., true) => (), - } - match (false, true, false) { (..) => (), } -} -"#, - ); - } - - #[test] - fn tuple_of_tuple_and_bools() { - check_diagnostics( - r#" -fn main() { - match (false, ((), false)) {} - //^^^^^^^^^^^^^^^^^^^^ Missing match arm - match (false, ((), false)) { (true, ((), true)) => (), } - //^^^^^^^^^^^^^^^^^^^^ Missing match arm - match (false, ((), false)) { (true, _) => (), } - //^^^^^^^^^^^^^^^^^^^^ Missing match arm - - match (false, ((), false)) { - (true, ((), true)) => (), - (true, ((), false)) => (), - (false, ((), true)) => (), - (false, ((), false)) => (), - } - match (false, ((), false)) { - (true, ((), true)) => (), - (true, ((), false)) => (), - (false, _) => (), - } -} -"#, - ); - } - - #[test] - fn enums() { - check_diagnostics( - r#" -enum Either { A, B, } - -fn main() { - match Either::A { } - //^^^^^^^^^ Missing match arm - match Either::B { Either::A => (), } - //^^^^^^^^^ Missing match arm - - match &Either::B { - //^^^^^^^^^^ Missing match arm - Either::A => (), - } - - match Either::B { - Either::A => (), Either::B => (), - } - match &Either::B { - Either::A => (), Either::B => (), - } -} -"#, - ); - } - - #[test] - fn enum_containing_bool() { - check_diagnostics( - r#" -enum Either { A(bool), B } - -fn main() { - match Either::B { } - //^^^^^^^^^ Missing match arm - match Either::B { - //^^^^^^^^^ Missing match arm - Either::A(true) => (), Either::B => () - } - - match Either::B { - Either::A(true) => (), - Either::A(false) => (), - Either::B => (), - } - match Either::B { - Either::B => (), - _ => (), - } - match Either::B { - Either::A(_) => (), - Either::B => (), - } - -} - "#, - ); - } - - #[test] - fn enum_different_sizes() { - check_diagnostics( - r#" -enum Either { A(bool), B(bool, bool) } - -fn main() { - match Either::A(false) { - //^^^^^^^^^^^^^^^^ Missing match arm - Either::A(_) => (), - Either::B(false, _) => (), - } - - match Either::A(false) { - Either::A(_) => (), - Either::B(true, _) => (), - Either::B(false, _) => (), - } - match Either::A(false) { - Either::A(true) | Either::A(false) => (), - Either::B(true, _) => (), - Either::B(false, _) => (), - } -} -"#, - ); - } - - #[test] - fn tuple_of_enum_no_diagnostic() { - check_diagnostics( - r#" -enum Either { A(bool), B(bool, bool) } -enum Either2 { C, D } - -fn main() { - match (Either::A(false), Either2::C) { - (Either::A(true), _) | (Either::A(false), _) => (), - (Either::B(true, _), Either2::C) => (), - (Either::B(false, _), Either2::C) => (), - (Either::B(_, _), Either2::D) => (), - } -} -"#, - ); - } - - #[test] - fn or_pattern_no_diagnostic() { - check_diagnostics( - r#" -enum Either {A, B} - -fn main() { - match (Either::A, Either::B) { - (Either::A | Either::B, _) => (), - } -}"#, - ) - } - - #[test] - fn mismatched_types() { - // Match statements with arms that don't match the - // expression pattern do not fire this diagnostic. - check_diagnostics( - r#" -enum Either { A, B } -enum Either2 { C, D } - -fn main() { - match Either::A { - Either2::C => (), - Either2::D => (), - } - match (true, false) { - (true, false, true) => (), - (true) => (), - } - match (0) { () => () } - match Unresolved::Bar { Unresolved::Baz => () } -} - "#, - ); - } - - #[test] - fn malformed_match_arm_tuple_enum_missing_pattern() { - // We are testing to be sure we don't panic here when the match - // arm `Either::B` is missing its pattern. - check_diagnostics( - r#" -enum Either { A, B(u32) } - -fn main() { - match Either::A { - Either::A => (), - Either::B() => (), - } -} -"#, - ); - } - - #[test] - fn expr_diverges() { - check_diagnostics( - r#" -enum Either { A, B } - -fn main() { - match loop {} { - Either::A => (), - Either::B => (), - } - match loop {} { - Either::A => (), - } - match loop { break Foo::A } { - //^^^^^^^^^^^^^^^^^^^^^ Missing match arm - Either::A => (), - } - match loop { break Foo::A } { - Either::A => (), - Either::B => (), - } -} -"#, - ); - } - - #[test] - fn expr_partially_diverges() { - check_diagnostics( - r#" -enum Either { A(T), B } - -fn foo() -> Either { Either::B } -fn main() -> u32 { - match foo() { - Either::A(val) => val, - Either::B => 0, - } -} -"#, - ); - } - - #[test] - fn enum_record() { - check_diagnostics( - r#" -enum Either { A { foo: bool }, B } - -fn main() { - let a = Either::A { foo: true }; - match a { } - //^ Missing match arm - match a { Either::A { foo: true } => () } - //^ Missing match arm - match a { - Either::A { } => (), - //^^^^^^^^^ Missing structure fields: - // | - foo - Either::B => (), - } - match a { - //^ Missing match arm - Either::A { } => (), - } //^^^^^^^^^ Missing structure fields: - // | - foo - - match a { - Either::A { foo: true } => (), - Either::A { foo: false } => (), - Either::B => (), - } - match a { - Either::A { foo: _ } => (), - Either::B => (), - } -} -"#, - ); - } - - #[test] - fn enum_record_fields_out_of_order() { - check_diagnostics( - r#" -enum Either { - A { foo: bool, bar: () }, - B, -} - -fn main() { - let a = Either::A { foo: true, bar: () }; - match a { - //^ Missing match arm - Either::A { bar: (), foo: false } => (), - Either::A { foo: true, bar: () } => (), - } - - match a { - Either::A { bar: (), foo: false } => (), - Either::A { foo: true, bar: () } => (), - Either::B => (), - } -} -"#, - ); - } - - #[test] - fn enum_record_ellipsis() { - check_diagnostics( - r#" -enum Either { - A { foo: bool, bar: bool }, - B, -} - -fn main() { - let a = Either::B; - match a { - //^ Missing match arm - Either::A { foo: true, .. } => (), - Either::B => (), - } - match a { - //^ Missing match arm - Either::A { .. } => (), - } - - match a { - Either::A { foo: true, .. } => (), - Either::A { foo: false, .. } => (), - Either::B => (), - } - - match a { - Either::A { .. } => (), - Either::B => (), - } -} -"#, - ); - } - - #[test] - fn enum_tuple_partial_ellipsis() { - check_diagnostics( - r#" -enum Either { - A(bool, bool, bool, bool), - B, -} - -fn main() { - match Either::B { - //^^^^^^^^^ Missing match arm - Either::A(true, .., true) => (), - Either::A(true, .., false) => (), - Either::A(false, .., false) => (), - Either::B => (), - } - match Either::B { - //^^^^^^^^^ Missing match arm - Either::A(true, .., true) => (), - Either::A(true, .., false) => (), - Either::A(.., true) => (), - Either::B => (), - } - - match Either::B { - Either::A(true, .., true) => (), - Either::A(true, .., false) => (), - Either::A(false, .., true) => (), - Either::A(false, .., false) => (), - Either::B => (), - } - match Either::B { - Either::A(true, .., true) => (), - Either::A(true, .., false) => (), - Either::A(.., true) => (), - Either::A(.., false) => (), - Either::B => (), - } -} -"#, - ); - } - - #[test] - fn never() { - check_diagnostics( - r#" -enum Never {} - -fn enum_(never: Never) { - match never {} -} -fn enum_ref(never: &Never) { - match never {} - //^^^^^ Missing match arm -} -fn bang(never: !) { - match never {} -} -"#, - ); - } - - #[test] - fn unknown_type() { - check_diagnostics( - r#" -enum Option { Some(T), None } - -fn main() { - // `Never` is deliberately not defined so that it's an uninferred type. - match Option::::None { - None => (), - Some(never) => match never {}, - } -} -"#, - ); - } - - #[test] - fn tuple_of_bools_with_ellipsis_at_end_missing_arm() { - check_diagnostics( - r#" -fn main() { - match (false, true, false) { - //^^^^^^^^^^^^^^^^^^^^ Missing match arm - (false, ..) => (), - } -}"#, - ); - } - - #[test] - fn tuple_of_bools_with_ellipsis_at_beginning_missing_arm() { - check_diagnostics( - r#" -fn main() { - match (false, true, false) { - //^^^^^^^^^^^^^^^^^^^^ Missing match arm - (.., false) => (), - } -}"#, - ); - } - - #[test] - fn tuple_of_bools_with_ellipsis_in_middle_missing_arm() { - check_diagnostics( - r#" -fn main() { - match (false, true, false) { - //^^^^^^^^^^^^^^^^^^^^ Missing match arm - (true, .., false) => (), - } -}"#, - ); - } - - #[test] - fn record_struct() { - check_diagnostics( - r#"struct Foo { a: bool } -fn main(f: Foo) { - match f {} - //^ Missing match arm - match f { Foo { a: true } => () } - //^ Missing match arm - match &f { Foo { a: true } => () } - //^^ Missing match arm - match f { Foo { a: _ } => () } - match f { - Foo { a: true } => (), - Foo { a: false } => (), - } - match &f { - Foo { a: true } => (), - Foo { a: false } => (), - } -} -"#, - ); - } - - #[test] - fn tuple_struct() { - check_diagnostics( - r#"struct Foo(bool); -fn main(f: Foo) { - match f {} - //^ Missing match arm - match f { Foo(true) => () } - //^ Missing match arm - match f { - Foo(true) => (), - Foo(false) => (), - } -} -"#, - ); - } - - #[test] - fn unit_struct() { - check_diagnostics( - r#"struct Foo; -fn main(f: Foo) { - match f {} - //^ Missing match arm - match f { Foo => () } -} -"#, - ); - } - - #[test] - fn record_struct_ellipsis() { - check_diagnostics( - r#"struct Foo { foo: bool, bar: bool } -fn main(f: Foo) { - match f { Foo { foo: true, .. } => () } - //^ Missing match arm - match f { - //^ Missing match arm - Foo { foo: true, .. } => (), - Foo { bar: false, .. } => () - } - match f { Foo { .. } => () } - match f { - Foo { foo: true, .. } => (), - Foo { foo: false, .. } => () - } -} -"#, - ); - } - - #[test] - fn internal_or() { - check_diagnostics( - r#" -fn main() { - enum Either { A(bool), B } - match Either::B { - //^^^^^^^^^ Missing match arm - Either::A(true | false) => (), - } -} -"#, - ); - } - - #[test] - fn no_panic_at_unimplemented_subpattern_type() { - check_diagnostics( - r#" -struct S { a: char} -fn main(v: S) { - match v { S{ a } => {} } - match v { S{ a: _x } => {} } - match v { S{ a: 'a' } => {} } - match v { S{..} => {} } - match v { _ => {} } - match v { } - //^ Missing match arm -} -"#, - ); - } - - #[test] - fn binding() { - check_diagnostics( - r#" -fn main() { - match true { - _x @ true => {} - false => {} - } - match true { _x @ true => {} } - //^^^^ Missing match arm -} -"#, - ); - } - - mod false_negatives { - //! The implementation of match checking here is a work in progress. As we roll this out, we - //! prefer false negatives to false positives (ideally there would be no false positives). This - //! test module should document known false negatives. Eventually we will have a complete - //! implementation of match checking and this module will be empty. - //! - //! The reasons for documenting known false negatives: - //! - //! 1. It acts as a backlog of work that can be done to improve the behavior of the system. - //! 2. It ensures the code doesn't panic when handling these cases. - use super::*; - - #[test] - fn integers() { - // We don't currently check integer exhaustiveness. - check_diagnostics( - r#" -fn main() { - match 5 { - 10 => (), - 11..20 => (), - } -} -"#, - ); - } - } -} From f46a42f73aa92ab66800c70d525ddc7e6529edd6 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Tue, 11 May 2021 18:24:39 +0500 Subject: [PATCH 27/35] Better tests: check if match checking bails out. --- crates/hir_ty/src/diagnostics/expr.rs | 2 + crates/hir_ty/src/diagnostics/match_check.rs | 68 +++++++++++++++++++- 2 files changed, 69 insertions(+), 1 deletion(-) diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index c6015d236515..0a7e6ee52d8e 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -346,6 +346,8 @@ impl<'a, 'b> ExprValidator<'a, 'b> { // fit the match expression, we skip this diagnostic. Skipping the entire // diagnostic rather than just not including this match arm is preferred // to avoid the chance of false positives. + #[cfg(test)] + match_check::tests::report_bail_out(db, self.owner, arm.pat, self.sink); return; } diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index aebadd391701..5f0cc4145c6e 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -339,9 +339,60 @@ impl PatternFoldable for PatKind { } #[cfg(test)] -mod tests { +pub(super) mod tests { + mod report { + use std::any::Any; + + use hir_def::{expr::PatId, DefWithBodyId}; + use hir_expand::{HirFileId, InFile}; + use syntax::SyntaxNodePtr; + + use crate::{ + db::HirDatabase, + diagnostics_sink::{Diagnostic, DiagnosticCode, DiagnosticSink}, + }; + + /// In tests, match check bails out loudly. + /// This helps to catch incorrect tests that pass due to false negatives. + pub(crate) fn report_bail_out( + db: &dyn HirDatabase, + def: DefWithBodyId, + pat: PatId, + sink: &mut DiagnosticSink, + ) { + let (_, source_map) = db.body_with_source_map(def); + if let Ok(source_ptr) = source_map.pat_syntax(pat) { + let pat_syntax_ptr = source_ptr.value.either(Into::into, Into::into); + sink.push(BailedOut { file: source_ptr.file_id, pat_syntax_ptr }); + } + } + + #[derive(Debug)] + struct BailedOut { + file: HirFileId, + pat_syntax_ptr: SyntaxNodePtr, + } + + impl Diagnostic for BailedOut { + fn code(&self) -> DiagnosticCode { + DiagnosticCode("internal:match-check-bailed-out") + } + fn message(&self) -> String { + format!("Internal: match check bailed out") + } + fn display_source(&self) -> InFile { + InFile { file_id: self.file, value: self.pat_syntax_ptr.clone() } + } + fn as_any(&self) -> &(dyn Any + Send + 'static) { + self + } + } + } + use crate::diagnostics::tests::check_diagnostics; + pub(crate) use self::report::report_bail_out; + #[test] fn empty_tuple() { check_diagnostics( @@ -589,14 +640,18 @@ enum Either2 { C, D } fn main() { match Either::A { Either2::C => (), + // ^^^^^^^^^^ Internal: match check bailed out Either2::D => (), } match (true, false) { (true, false, true) => (), + // ^^^^^^^^^^^^^^^^^^^ Internal: match check bailed out (true) => (), } match (true, false) { (true,) => {} } + // ^^^^^^^ Internal: match check bailed out match (0) { () => () } + // ^^ Internal: match check bailed out match Unresolved::Bar { Unresolved::Baz => () } } "#, @@ -609,7 +664,9 @@ fn main() { r#" fn main() { match false { true | () => {} } + // ^^^^^^^^^ Internal: match check bailed out match (false,) { (true | (),) => {} } + // ^^^^^^^^^^^^ Internal: match check bailed out } "#, ); @@ -642,10 +699,12 @@ enum Either { A, B } fn main() { match loop {} { Either::A => (), + // ^^^^^^^^^ Internal: match check bailed out Either::B => (), } match loop {} { Either::A => (), + // ^^^^^^^^^ Internal: match check bailed out } match loop { break Foo::A } { //^^^^^^^^^^^^^^^^^^^^^ Missing match arm @@ -853,6 +912,11 @@ fn main() { match Option::::None { None => (), Some(never) => match never {}, + // ^^^^^^^^^^^ Internal: match check bailed out + } + match Option::::None { + //^^^^^^^^^^^^^^^^^^^^^ Missing match arm + Option::Some(_never) => {}, } } "#, @@ -1000,6 +1064,7 @@ fn main(v: S) { match v { S{ a } => {} } match v { S{ a: _x } => {} } match v { S{ a: 'a' } => {} } + //^^^^^^^^^^^ Internal: match check bailed out match v { S{..} => {} } match v { _ => {} } match v { } @@ -1045,6 +1110,7 @@ fn main() { fn main() { match 5 { 10 => (), + // ^^ Internal: match check bailed out 11..20 => (), } } From 4cce7a6407821f456741a8d512ae31da3128c84f Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Wed, 12 May 2021 11:04:56 +0500 Subject: [PATCH 28/35] Box field detection; test #[non-exhaustive] attribute --- crates/hir_ty/src/diagnostics/match_check.rs | 36 +++++++++++++++++++ .../match_check/deconstruct_pat.rs | 22 +++++++----- .../src/diagnostics/match_check/usefulness.rs | 4 +-- 3 files changed, 52 insertions(+), 10 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index 5f0cc4145c6e..061ef754db28 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -1090,6 +1090,42 @@ fn main() { ); } + #[test] + fn enum_non_exhaustive() { + check_diagnostics( + r#" +//- /lib.rs crate:lib +#[non_exhaustive] +pub enum E { A, B } +fn _local() { + match E::A { _ => {} } + match E::A { + E::A => {} + E::B => {} + } + match E::A { + E::A | E::B => {} + } +} + +//- /main.rs crate:main deps:lib +use lib::E; +fn main() { + match E::A { _ => {} } + match E::A { + //^^^^ Missing match arm + E::A => {} + E::B => {} + } + match E::A { + //^^^^ Missing match arm + E::A | E::B => {} + } +} +"#, + ); + } + mod false_negatives { //! The implementation of match checking here is a work in progress. As we roll this out, we //! prefer false negatives to false positives (ideally there would be no false positives). This diff --git a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs index 9fa82a952ac0..6711fbb4ae7f 100644 --- a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs @@ -513,9 +513,7 @@ impl SplitWildcard { if is_secretly_empty || is_declared_nonexhaustive { smallvec![NonExhaustive] } else if cx.feature_exhaustive_patterns() { - // If `exhaustive_patterns` is enabled, we exclude variants known to be - // uninhabited. - unhandled() + unimplemented!() // see MatchCheckCtx.feature_exhaustive_patterns() } else { enum_data .variants @@ -643,6 +641,7 @@ impl Fields { Fields::Vec(pats) } + /// Creates a new list of wildcard fields for a given constructor. pub(crate) fn wildcards(pcx: PatCtxt<'_>, constructor: &Constructor) -> Self { let ty = pcx.ty; let cx = pcx.cx; @@ -655,14 +654,13 @@ impl Fields { Fields::wildcards_from_tys(cx, tys) } TyKind::Ref(.., rty) => Fields::from_single_pattern(wildcard_from_ty(rty)), - TyKind::Adt(AdtId(adt), substs) => { - let adt_is_box = false; // TODO(iDawer): implement this - if adt_is_box { + &TyKind::Adt(AdtId(adt), ref substs) => { + if adt_is_box(adt, cx) { // Use T as the sub pattern type of Box. let subst_ty = substs.at(&Interner, 0).assert_ty_ref(&Interner); Fields::from_single_pattern(wildcard_from_ty(subst_ty)) } else { - let variant_id = constructor.variant_id_for_adt(*adt); + let variant_id = constructor.variant_id_for_adt(adt); let adt_is_local = variant_id.module(cx.db.upcast()).krate() == cx.module.krate(); // Whether we must not match the fields of this variant exhaustively. @@ -680,7 +678,7 @@ impl Fields { if has_no_hidden_fields { Fields::wildcards_from_tys(cx, field_tys()) } else { - //FIXME(iDawer): see MatchCheckCtx::is_uninhabited + //FIXME(iDawer): see MatchCheckCtx::is_uninhabited, has_no_hidden_fields is always true unimplemented!("exhaustive_patterns feature") } } @@ -892,3 +890,11 @@ fn is_field_list_non_exhaustive(variant_id: VariantId, cx: &MatchCheckCtx<'_>) - }; cx.db.attrs(attr_def_id).by_key("non_exhaustive").exists() } + +fn adt_is_box(adt: hir_def::AdtId, cx: &MatchCheckCtx<'_>) -> bool { + use hir_def::lang_item::LangItemTarget; + match cx.db.lang_item(cx.module.krate(), "owned_box".into()) { + Some(LangItemTarget::StructId(box_id)) => adt == box_id.into(), + _ => false, + } +} diff --git a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs index b01e3557cac0..44e08b6e9e96 100644 --- a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs @@ -293,7 +293,7 @@ pub(crate) struct MatchCheckCtx<'a> { pub(crate) match_expr: ExprId, pub(crate) infer: &'a InferenceResult, pub(crate) db: &'a dyn HirDatabase, - /// Lowered patterns from self.body.pats plus generated by the check. + /// Lowered patterns from arms plus generated by the check. pub(crate) pattern_arena: &'a RefCell, } @@ -315,7 +315,7 @@ impl<'a> MatchCheckCtx<'a> { // Rust feature described as "Allows exhaustive pattern matching on types that contain uninhabited types." pub(super) fn feature_exhaustive_patterns(&self) -> bool { - // TODO + // FIXME see MatchCheckCtx::is_uninhabited false } From 977ba46bb113c9e9ec159f01a72f51a0a7b92c1b Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Wed, 12 May 2021 12:50:22 +0500 Subject: [PATCH 29/35] Test match guards, reference patterns --- crates/hir_ty/src/diagnostics/match_check.rs | 51 ++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index 061ef754db28..5fb98ff35c62 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -1126,6 +1126,25 @@ fn main() { ); } + #[test] + fn match_guard() { + check_diagnostics( + r#" +fn main() { + match true { + true if false => {} + true => {} + false => {} + } + match true { + //^^^^ Missing match arm + true if false => {} + false => {} +} +"#, + ); + } + mod false_negatives { //! The implementation of match checking here is a work in progress. As we roll this out, we //! prefer false negatives to false positives (ideally there would be no false positives). This @@ -1153,5 +1172,37 @@ fn main() { "#, ); } + + #[test] + fn reference_patterns_at_top_level() { + check_diagnostics( + r#" +fn main() { + match &false { + &true => {} + // ^^^^^ Internal: match check bailed out + } +} + "#, + ); + } + + #[test] + fn reference_patterns_in_fields() { + check_diagnostics( + r#" +fn main() { + match (&false,) { + (true,) => {} + // ^^^^^^^ Internal: match check bailed out + } + match (&false,) { + (&true,) => {} + // ^^^^^^^^ Internal: match check bailed out + } +} + "#, + ); + } } } From f571b62a13aff662c9d1c17206342479f8529633 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Sun, 16 May 2021 18:11:45 +0500 Subject: [PATCH 30/35] minor: doc comment pat_util --- crates/hir_ty/src/diagnostics/match_check/pat_util.rs | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/crates/hir_ty/src/diagnostics/match_check/pat_util.rs b/crates/hir_ty/src/diagnostics/match_check/pat_util.rs index eb0b07a52295..b89b4f2bfb7d 100644 --- a/crates/hir_ty/src/diagnostics/match_check/pat_util.rs +++ b/crates/hir_ty/src/diagnostics/match_check/pat_util.rs @@ -1,3 +1,7 @@ +//! Pattern untilities. +//! +//! Originates from `rustc_hir::pat_util` + use std::iter::{Enumerate, ExactSizeIterator}; pub(crate) struct EnumerateAndAdjust { From e16f413582ea45d6b318337ea2c7838fdc3b82a4 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Wed, 19 May 2021 18:00:25 +0500 Subject: [PATCH 31/35] eprint panic context --- crates/hir_ty/src/diagnostics/expr.rs | 12 ++++++++ .../match_check/deconstruct_pat.rs | 29 ++++++++++--------- .../src/diagnostics/match_check/usefulness.rs | 9 +++++- 3 files changed, 36 insertions(+), 14 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index 0a7e6ee52d8e..44d5f6b225af 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -357,6 +357,18 @@ impl<'a, 'b> ExprValidator<'a, 'b> { infer: &infer, db, pattern_arena: &pattern_arena, + eprint_panic_context: &|| { + use syntax::AstNode; + if let Ok(scrutinee_sptr) = source_map.expr_syntax(match_expr) { + let root = scrutinee_sptr.file_syntax(db.upcast()); + if let Some(match_ast) = scrutinee_sptr.value.to_node(&root).syntax().parent() { + eprintln!( + "Match checking is about to panic on this expression:\n{}", + match_ast.to_string(), + ); + } + } + }, }; let report = compute_match_usefulness(&cx, &m_arms); diff --git a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs index 6711fbb4ae7f..15ec5cf45011 100644 --- a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs @@ -328,7 +328,7 @@ impl Constructor { PatKind::Leaf { .. } | PatKind::Deref { .. } => Single, &PatKind::Variant { enum_variant, .. } => Variant(enum_variant), &PatKind::LiteralBool { value } => IntRange(IntRange::from_bool(value)), - PatKind::Or { .. } => panic!("bug: Or-pattern should have been expanded earlier on."), + PatKind::Or { .. } => cx.bug("Or-pattern should have been expanded earlier on."), } } @@ -375,7 +375,7 @@ impl Constructor { /// this checks for inclusion. // We inline because this has a single call site in `Matrix::specialize_constructor`. #[inline] - pub(super) fn is_covered_by(&self, _pcx: PatCtxt<'_>, other: &Self) -> bool { + pub(super) fn is_covered_by(&self, pcx: PatCtxt<'_>, other: &Self) -> bool { // This must be kept in sync with `is_covered_by_any`. match (self, other) { // Wildcards cover anything @@ -400,17 +400,17 @@ impl Constructor { // Only a wildcard pattern can match the special extra constructor. (NonExhaustive, _) => false, - _ => panic!( - "bug: trying to compare incompatible constructors {:?} and {:?}", + _ => pcx.cx.bug(&format!( + "trying to compare incompatible constructors {:?} and {:?}", self, other - ), + )), } } /// Faster version of `is_covered_by` when applied to many constructors. `used_ctors` is /// assumed to be built from `matrix.head_ctors()` with wildcards filtered out, and `self` is /// assumed to have been split from a wildcard. - fn is_covered_by_any(&self, _pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bool { + fn is_covered_by_any(&self, pcx: PatCtxt<'_>, used_ctors: &[Constructor]) -> bool { if used_ctors.is_empty() { return false; } @@ -431,7 +431,7 @@ impl Constructor { // This constructor is never covered by anything else NonExhaustive => false, Str(..) | FloatRange(..) | Opaque | Missing | Wildcard => { - panic!("bug: found unexpected ctor in all_ctors: {:?}", self) + pcx.cx.bug(&format!("found unexpected ctor in all_ctors: {:?}", self)) } } } @@ -683,7 +683,9 @@ impl Fields { } } } - _ => panic!("Unexpected type for `Single` constructor: {:?}", ty), + ty_kind => { + cx.bug(&format!("Unexpected type for `Single` constructor: {:?}", ty_kind)) + } }, Slice(..) => { unimplemented!() @@ -748,7 +750,7 @@ impl Fields { // can ignore this issue. TyKind::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() }, TyKind::Slice(..) | TyKind::Array(..) => { - panic!("bug: bad slice pattern {:?} {:?}", ctor, pcx.ty) + pcx.cx.bug(&format!("bad slice pattern {:?} {:?}", ctor, pcx.ty)) } _ => PatKind::Wild, }, @@ -758,10 +760,11 @@ impl Fields { Constructor::IntRange(_) => UNHANDLED, NonExhaustive => PatKind::Wild, Wildcard => return Pat::wildcard_from_ty(pcx.ty), - Opaque => panic!("bug: we should not try to apply an opaque constructor"), - Missing => { - panic!("bug: trying to apply the `Missing` constructor; this should have been done in `apply_constructors`") - } + Opaque => pcx.cx.bug("we should not try to apply an opaque constructor"), + Missing => pcx.cx.bug( + "trying to apply the `Missing` constructor;\ + this should have been done in `apply_constructors`", + ), }; Pat { ty: pcx.ty.clone(), kind: Box::new(pat) } diff --git a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs index 44e08b6e9e96..cb322a3de36c 100644 --- a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs @@ -295,6 +295,7 @@ pub(crate) struct MatchCheckCtx<'a> { pub(crate) db: &'a dyn HirDatabase, /// Lowered patterns from arms plus generated by the check. pub(crate) pattern_arena: &'a RefCell, + pub(crate) eprint_panic_context: &'a dyn Fn(), } impl<'a> MatchCheckCtx<'a> { @@ -327,6 +328,12 @@ impl<'a> MatchCheckCtx<'a> { pub(super) fn type_of(&self, pat: PatId) -> Ty { self.pattern_arena.borrow()[pat].ty.clone() } + + #[track_caller] + pub(super) fn bug(&self, info: &str) -> ! { + (self.eprint_panic_context)(); + panic!("bug: {}", info); + } } #[derive(Copy, Clone)] @@ -737,7 +744,7 @@ impl SubPatSet { } Seq { subpats: new_subpats } } - Alt { .. } => panic!("bug"), + Alt { .. } => panic!("bug"), // `self` is a patstack } } From 3088ca0a53540e0d7ae14f0d18efcad16cad0735 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Wed, 19 May 2021 18:08:13 +0500 Subject: [PATCH 32/35] Take substitutions into account. --- crates/hir_ty/src/diagnostics/match_check.rs | 20 +++++++++++++-- .../match_check/deconstruct_pat.rs | 25 +++++++++++-------- .../src/diagnostics/match_check/usefulness.rs | 2 +- 3 files changed, 33 insertions(+), 14 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index 5fb98ff35c62..992bb868222b 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -39,8 +39,8 @@ pub(crate) struct Pat { } impl Pat { - pub(crate) fn wildcard_from_ty(ty: &Ty) -> Self { - Pat { ty: ty.clone(), kind: Box::new(PatKind::Wild) } + pub(crate) fn wildcard_from_ty(ty: Ty) -> Self { + Pat { ty, kind: Box::new(PatKind::Wild) } } } @@ -1145,6 +1145,22 @@ fn main() { ); } + #[test] + fn pattern_type_is_of_substitution() { + cov_mark::check!(match_check_wildcard_expanded_to_substitutions); + check_diagnostics( + r#" +struct Foo(T); +struct Bar; +fn main() { + match Foo(Bar) { + _ | Foo(Bar) => {} + } +} +"#, + ); + } + mod false_negatives { //! The implementation of match checking here is a work in progress. As we roll this out, we //! prefer false negatives to false positives (ideally there would be no false positives). This diff --git a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs index 15ec5cf45011..a470826174c4 100644 --- a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs @@ -632,10 +632,7 @@ impl Fields { } /// Convenience; internal use. - fn wildcards_from_tys<'a>( - cx: &MatchCheckCtx<'_>, - tys: impl IntoIterator, - ) -> Self { + fn wildcards_from_tys(cx: &MatchCheckCtx<'_>, tys: impl IntoIterator) -> Self { let wilds = tys.into_iter().map(Pat::wildcard_from_ty); let pats = wilds.map(|pat| cx.alloc_pat(pat)).collect(); Fields::Vec(pats) @@ -645,13 +642,13 @@ impl Fields { pub(crate) fn wildcards(pcx: PatCtxt<'_>, constructor: &Constructor) -> Self { let ty = pcx.ty; let cx = pcx.cx; - let wildcard_from_ty = |ty| cx.alloc_pat(Pat::wildcard_from_ty(ty)); + let wildcard_from_ty = |ty: &Ty| cx.alloc_pat(Pat::wildcard_from_ty(ty.clone())); let ret = match constructor { Single | Variant(_) => match ty.kind(&Interner) { TyKind::Tuple(_, substs) => { let tys = substs.iter(&Interner).map(|ty| ty.assert_ty_ref(&Interner)); - Fields::wildcards_from_tys(cx, tys) + Fields::wildcards_from_tys(cx, tys.cloned()) } TyKind::Ref(.., rty) => Fields::from_single_pattern(wildcard_from_ty(rty)), &TyKind::Adt(AdtId(adt), ref substs) => { @@ -666,14 +663,20 @@ impl Fields { // Whether we must not match the fields of this variant exhaustively. let is_non_exhaustive = is_field_list_non_exhaustive(variant_id, cx) && !adt_is_local; - let field_ty_arena = cx.db.field_types(variant_id); - let field_tys = - || field_ty_arena.iter().map(|(_, binders)| binders.skip_binders()); + + cov_mark::hit!(match_check_wildcard_expanded_to_substitutions); + let field_ty_data = cx.db.field_types(variant_id); + let field_tys = || { + field_ty_data + .iter() + .map(|(_, binders)| binders.clone().substitute(&Interner, substs)) + }; + // In the following cases, we don't need to filter out any fields. This is // the vast majority of real cases, since uninhabited fields are uncommon. let has_no_hidden_fields = (matches!(adt, hir_def::AdtId::EnumId(_)) && !is_non_exhaustive) - || !field_tys().any(|ty| cx.is_uninhabited(ty)); + || !field_tys().any(|ty| cx.is_uninhabited(&ty)); if has_no_hidden_fields { Fields::wildcards_from_tys(cx, field_tys()) @@ -759,7 +762,7 @@ impl Fields { FloatRange(..) => UNHANDLED, Constructor::IntRange(_) => UNHANDLED, NonExhaustive => PatKind::Wild, - Wildcard => return Pat::wildcard_from_ty(pcx.ty), + Wildcard => return Pat::wildcard_from_ty(pcx.ty.clone()), Opaque => pcx.cx.bug("we should not try to apply an opaque constructor"), Missing => pcx.cx.bug( "trying to apply the `Missing` constructor;\ diff --git a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs index cb322a3de36c..61fba41bf8db 100644 --- a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs @@ -1152,7 +1152,7 @@ pub(crate) fn compute_match_usefulness( .collect(); let wild_pattern = - cx.pattern_arena.borrow_mut().alloc(Pat::wildcard_from_ty(&cx.infer[cx.match_expr])); + cx.pattern_arena.borrow_mut().alloc(Pat::wildcard_from_ty(cx.infer[cx.match_expr].clone())); let v = PatStack::from_pattern(wild_pattern); let usefulness = is_useful(cx, &matrix, &v, ConstructWitness, false, true); let non_exhaustiveness_witnesses = match usefulness { From 4899ac8c053ef782c25c87b12b54dbcbfdb5e0fb Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Sat, 22 May 2021 12:36:48 +0500 Subject: [PATCH 33/35] Correct binding pattern's type; handle invalid records. --- crates/hir_ty/src/diagnostics/match_check.rs | 60 ++++++++++++++++++-- 1 file changed, 55 insertions(+), 5 deletions(-) diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index 992bb868222b..1d250413d221 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -24,6 +24,7 @@ pub(crate) type PatId = Idx; pub(crate) enum PatternError { Unimplemented, UnresolvedVariant, + MissingField, } #[derive(Clone, Debug, PartialEq)] @@ -105,7 +106,7 @@ impl<'a> PatCtxt<'a> { } fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat { - let ty = &self.infer[pat]; + let mut ty = &self.infer[pat]; let variant = self.infer.variant_resolution_for_pat(pat); let kind = match self.body[pat] { @@ -127,6 +128,9 @@ impl<'a> PatCtxt<'a> { } hir_def::expr::Pat::Bind { subpat, .. } => { + if let TyKind::Ref(.., rty) = ty.kind(&Interner) { + ty = rty; + } PatKind::Binding { subpattern: self.lower_opt_pattern(subpat) } } @@ -140,13 +144,21 @@ impl<'a> PatCtxt<'a> { let variant_data = variant.unwrap().variant_data(self.db.upcast()); let subpatterns = args .iter() - .map(|field| FieldPat { + .map(|field| { // XXX(iDawer): field lookup is inefficient - field: variant_data.field(&field.name).unwrap(), - pattern: self.lower_pattern(field.pat), + variant_data.field(&field.name).map(|lfield_id| FieldPat { + field: lfield_id, + pattern: self.lower_pattern(field.pat), + }) }) .collect(); - self.lower_variant_or_leaf(pat, ty, subpatterns) + match subpatterns { + Some(subpatterns) => self.lower_variant_or_leaf(pat, ty, subpatterns), + None => { + self.errors.push(PatternError::MissingField); + PatKind::Wild + } + } } hir_def::expr::Pat::TupleStruct { .. } | hir_def::expr::Pat::Record { .. } => { self.errors.push(PatternError::UnresolvedVariant); @@ -1090,6 +1102,31 @@ fn main() { ); } + #[test] + fn binding_ref_has_correct_type() { + // Asserts `PatKind::Binding(ref _x): bool`, not &bool. + // If that's not true match checking will panic with "incompatible constructors" + // FIXME: make facilities to test this directly like `tests::check_infer(..)` + check_diagnostics( + r#" +enum Foo { A } +fn main() { + // FIXME: this should not bail out but current behavior is such as the old algorithm. + // ExprValidator::validate_match(..) checks types of top level patterns incorrecly. + match Foo::A { + ref _x => {} + // ^^^^^^ Internal: match check bailed out + Foo::A => {} + } + match (true,) { + (ref _x,) => {} + (true,) => {} + } +} +"#, + ); + } + #[test] fn enum_non_exhaustive() { check_diagnostics( @@ -1161,6 +1198,19 @@ fn main() { ); } + #[test] + fn record_struct_no_such_field() { + check_diagnostics( + r#" +struct Foo { } +fn main(f: Foo) { + match f { Foo { bar } => () } + // ^^^^^^^^^^^ Internal: match check bailed out +} +"#, + ); + } + mod false_negatives { //! The implementation of match checking here is a work in progress. As we roll this out, we //! prefer false negatives to false positives (ideally there would be no false positives). This From 31b6a750f8e37d011060a17ffd816d721d087844 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Mon, 24 May 2021 17:03:36 +0500 Subject: [PATCH 34/35] fix: panic on extra fields in a pattern --- crates/hir_ty/src/diagnostics/match_check.rs | 25 ++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs index 1d250413d221..a9a99f57a249 100644 --- a/crates/hir_ty/src/diagnostics/match_check.rs +++ b/crates/hir_ty/src/diagnostics/match_check.rs @@ -25,6 +25,7 @@ pub(crate) enum PatternError { Unimplemented, UnresolvedVariant, MissingField, + ExtraFields, } #[derive(Clone, Debug, PartialEq)] @@ -182,6 +183,11 @@ impl<'a> PatCtxt<'a> { expected_len: usize, ellipsis: Option, ) -> Vec { + if pats.len() > expected_len { + self.errors.push(PatternError::ExtraFields); + return Vec::new(); + } + pats.iter() .enumerate_and_adjust(expected_len, ellipsis) .map(|(i, &subpattern)| FieldPat { @@ -702,6 +708,25 @@ fn main() { ); } + #[test] + fn malformed_match_arm_extra_fields() { + check_diagnostics( + r#" +enum A { B(isize, isize), C } +fn main() { + match A::B(1, 2) { + A::B(_, _, _) => (), + // ^^^^^^^^^^^^^ Internal: match check bailed out + } + match A::B(1, 2) { + A::C(_) => (), + // ^^^^^^^ Internal: match check bailed out + } +} +"#, + ); + } + #[test] fn expr_diverges() { check_diagnostics( From e7c49666be180eba2720cce09d4d2116b1ef4d20 Mon Sep 17 00:00:00 2001 From: Dawer <7803845+iDawer@users.noreply.github.com> Date: Tue, 1 Jun 2021 01:44:51 +0500 Subject: [PATCH 35/35] Expand fixme comments --- crates/hir_def/src/path.rs | 5 ++++- crates/hir_ty/src/diagnostics/expr.rs | 1 + crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs | 3 ++- crates/hir_ty/src/diagnostics/match_check/usefulness.rs | 3 ++- 4 files changed, 9 insertions(+), 3 deletions(-) diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs index f98622faac88..4cdb5913deb5 100644 --- a/crates/hir_def/src/path.rs +++ b/crates/hir_def/src/path.rs @@ -166,7 +166,10 @@ impl Path { } /// Converts a known mod path to `Path`. - pub fn from_known_path(path: ModPath, generic_args: Vec>>) -> Path { + pub fn from_known_path( + path: ModPath, + generic_args: Vec>>, + ) -> Path { Path { type_anchor: None, mod_path: Interned::new(path), generic_args } } diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs index 44d5f6b225af..3efbce77361e 100644 --- a/crates/hir_ty/src/diagnostics/expr.rs +++ b/crates/hir_ty/src/diagnostics/expr.rs @@ -376,6 +376,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> { // https://github.com/rust-lang/rust/blob/25c15cdbe/compiler/rustc_mir_build/src/thir/pattern/check_match.rs#L200-L201 let witnesses = report.non_exhaustiveness_witnesses; + // FIXME Report witnesses // eprintln!("compute_match_usefulness(..) -> {:?}", &witnesses); if !witnesses.is_empty() { if let Ok(source_ptr) = source_map.expr_syntax(id) { diff --git a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs index a470826174c4..1f4219b4226e 100644 --- a/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs +++ b/crates/hir_ty/src/diagnostics/match_check/deconstruct_pat.rs @@ -864,7 +864,8 @@ impl Fields { pat: PatId, cx: &MatchCheckCtx<'_>, ) -> Self { - // FIXME(iDawer): these alocations and clones are so unfortunate (+1 for switching to references) + // FIXME(iDawer): Factor out pattern deep cloning. See discussion: + // https://github.com/rust-analyzer/rust-analyzer/pull/8717#discussion_r633086640 let mut arena = cx.pattern_arena.borrow_mut(); match arena[pat].kind.as_ref() { PatKind::Deref { subpattern } => { diff --git a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs index 61fba41bf8db..83b094a89383 100644 --- a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs +++ b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs @@ -376,9 +376,10 @@ impl PatIdExt for PatId { fn expand_or_pat(self, cx: &MatchCheckCtx<'_>) -> Vec { fn expand(pat: PatId, vec: &mut Vec, pat_arena: &mut PatternArena) { if let PatKind::Or { pats } = pat_arena[pat].kind.as_ref() { + // FIXME(iDawer): Factor out pattern deep cloning. See discussion: + // https://github.com/rust-analyzer/rust-analyzer/pull/8717#discussion_r633086640 let pats = pats.clone(); for pat in pats { - // FIXME(iDawer): Ugh, I want to go back to references (PatId -> &Pat) let pat = pat_arena.alloc(pat.clone()); expand(pat, vec, pat_arena); }