Suggest a FnPtr type if a FnDef type is found
This commit is contained in:
Fabian Wolff
parent
f687d5c43a
commit
79dc9a76a6
3 changed files with 74 additions and 39 deletions
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@ -9,7 +9,7 @@ use rustc_hir::{HirId, Node};
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use rustc_middle::hir::map::Map;
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use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts};
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use rustc_middle::ty::util::IntTypeExt;
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use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt, TypeFoldable};
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use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt, TypeFoldable, TypeFolder};
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use rustc_span::symbol::Ident;
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use rustc_span::{Span, DUMMY_SP};
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@ -749,15 +749,38 @@ fn infer_placeholder_type(
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span: Span,
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item_ident: Ident,
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) -> Ty<'_> {
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fn contains_anonymous(ty: Ty<'_>) -> bool {
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for gen_arg in ty.walk() {
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if let ty::subst::GenericArgKind::Type(inner_ty) = gen_arg.unpack() {
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if let ty::FnDef(..) | ty::Closure(..) | ty::Generator(..) = inner_ty.kind() {
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return true;
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// Attempts to make the type nameable by turning FnDefs into FnPtrs.
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struct MakeNameable<'tcx> {
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success: bool,
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tcx: TyCtxt<'tcx>,
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}
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impl<'tcx> MakeNameable<'tcx> {
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fn new(tcx: TyCtxt<'tcx>) -> Self {
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MakeNameable { success: true, tcx }
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}
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}
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impl TypeFolder<'tcx> for MakeNameable<'tcx> {
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fn tcx(&self) -> TyCtxt<'tcx> {
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self.tcx
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}
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fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
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if !self.success {
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return ty;
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}
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match ty.kind() {
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ty::FnDef(def_id, _) => self.tcx.mk_fn_ptr(self.tcx.fn_sig(*def_id)),
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// FIXME: non-capturing closures should also suggest a function pointer
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ty::Closure(..) | ty::Generator(..) => {
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self.success = false;
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ty
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}
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_ => ty.super_fold_with(self),
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}
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}
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false
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}
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let ty = tcx.diagnostic_only_typeck(def_id).node_type(body_id.hir_id);
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@ -773,11 +796,14 @@ fn infer_placeholder_type(
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err.suggestions.clear();
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// Suggesting unnameable types won't help.
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if !contains_anonymous(ty) {
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let mut mk_nameable = MakeNameable::new(tcx);
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let ty = mk_nameable.fold_ty(ty);
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let sugg_ty = if mk_nameable.success { Some(ty) } else { None };
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if let Some(sugg_ty) = sugg_ty {
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err.span_suggestion(
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span,
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"provide a type for the item",
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format!("{}: {}", item_ident, ty),
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format!("{}: {}", item_ident, sugg_ty),
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Applicability::MachineApplicable,
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);
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} else {
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@ -793,11 +819,14 @@ fn infer_placeholder_type(
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let mut diag = bad_placeholder_type(tcx, vec![span]);
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if !ty.references_error() {
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if !contains_anonymous(ty) {
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let mut mk_nameable = MakeNameable::new(tcx);
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let ty = mk_nameable.fold_ty(ty);
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let sugg_ty = if mk_nameable.success { Some(ty) } else { None };
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if let Some(sugg_ty) = sugg_ty {
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diag.span_suggestion(
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span,
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"replace with the correct type",
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ty.to_string(),
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sugg_ty.to_string(),
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Applicability::MaybeIncorrect,
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);
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} else {
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@ -13,21 +13,27 @@ static B: _ = "abc";
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//~| HELP: replace with the correct type
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// FIXME: this should also suggest a function pointer, as the closure is non-capturing
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const C: _ = || 42;
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//~^ ERROR: the type placeholder `_` is not allowed within types on item signatures
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//~| NOTE: not allowed in type signatures
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//~| NOTE: however, the inferred type
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struct S<T> { t: T }
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const D = S { t: || -> i32 { 42 } };
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const D = S { t: { let i = 0; move || -> i32 { i } } };
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//~^ ERROR: missing type for `const` item
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//~| NOTE: however, the inferred type
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fn foo() -> i32 { 42 }
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const E = S { t: foo };
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const E = foo;
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//~^ ERROR: missing type for `const` item
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//~| NOTE: however, the inferred type
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//~| HELP: provide a type for the item
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const F = S { t: foo };
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//~^ ERROR: missing type for `const` item
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//~| HELP: provide a type for the item
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const F = || -> i32 { yield 0; return 1; };
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const G = || -> i32 { yield 0; return 1; };
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//~^ ERROR: missing type for `const` item
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//~| NOTE: however, the inferred type
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@ -14,53 +14,53 @@ LL | static B: _ = "abc";
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| help: replace with the correct type: `&str`
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error[E0121]: the type placeholder `_` is not allowed within types on item signatures
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--> $DIR/unnamable-types.rs:16:10
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--> $DIR/unnamable-types.rs:17:10
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LL | const C: _ = || 42;
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| ^ not allowed in type signatures
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note: however, the inferred type `[closure@$DIR/unnamable-types.rs:16:14: 16:19]` cannot be named
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--> $DIR/unnamable-types.rs:16:14
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note: however, the inferred type `[closure@$DIR/unnamable-types.rs:17:14: 17:19]` cannot be named
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--> $DIR/unnamable-types.rs:17:14
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LL | const C: _ = || 42;
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| ^^^^^
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error: missing type for `const` item
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--> $DIR/unnamable-types.rs:22:7
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--> $DIR/unnamable-types.rs:23:7
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LL | const D = S { t: || -> i32 { 42 } };
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LL | const D = S { t: { let i = 0; move || -> i32 { i } } };
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| ^
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note: however, the inferred type `S<[closure@$DIR/unnamable-types.rs:22:18: 22:34]>` cannot be named
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--> $DIR/unnamable-types.rs:22:11
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note: however, the inferred type `S<[closure@$DIR/unnamable-types.rs:23:31: 23:51]>` cannot be named
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--> $DIR/unnamable-types.rs:23:11
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LL | const D = S { t: || -> i32 { 42 } };
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| ^^^^^^^^^^^^^^^^^^^^^^^^^
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LL | const D = S { t: { let i = 0; move || -> i32 { i } } };
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: missing type for `const` item
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--> $DIR/unnamable-types.rs:27:7
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--> $DIR/unnamable-types.rs:29:7
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LL | const E = S { t: foo };
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| ^
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note: however, the inferred type `S<fn() -> i32 {foo}>` cannot be named
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--> $DIR/unnamable-types.rs:27:11
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LL | const E = S { t: foo };
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| ^^^^^^^^^^^^
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LL | const E = foo;
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| ^ help: provide a type for the item: `E: fn() -> i32`
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error: missing type for `const` item
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--> $DIR/unnamable-types.rs:31:7
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--> $DIR/unnamable-types.rs:32:7
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LL | const F = || -> i32 { yield 0; return 1; };
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LL | const F = S { t: foo };
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| ^ help: provide a type for the item: `F: S<fn() -> i32>`
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error: missing type for `const` item
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--> $DIR/unnamable-types.rs:37:7
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LL | const G = || -> i32 { yield 0; return 1; };
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| ^
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note: however, the inferred type `[generator@$DIR/unnamable-types.rs:31:11: 31:43 {i32, ()}]` cannot be named
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--> $DIR/unnamable-types.rs:31:11
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note: however, the inferred type `[generator@$DIR/unnamable-types.rs:37:11: 37:43 {i32, ()}]` cannot be named
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--> $DIR/unnamable-types.rs:37:11
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LL | const F = || -> i32 { yield 0; return 1; };
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LL | const G = || -> i32 { yield 0; return 1; };
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: aborting due to 6 previous errors
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error: aborting due to 7 previous errors
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For more information about this error, try `rustc --explain E0121`.
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