1660 lines
67 KiB
Rust
1660 lines
67 KiB
Rust
//! Error Reporting Code for the inference engine
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//!
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//! Because of the way inference, and in particular region inference,
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//! works, it often happens that errors are not detected until far after
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//! the relevant line of code has been type-checked. Therefore, there is
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//! an elaborate system to track why a particular constraint in the
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//! inference graph arose so that we can explain to the user what gave
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//! rise to a particular error.
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//!
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//! The basis of the system are the "origin" types. An "origin" is the
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//! reason that a constraint or inference variable arose. There are
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//! different "origin" enums for different kinds of constraints/variables
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//! (e.g., `TypeOrigin`, `RegionVariableOrigin`). An origin always has
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//! a span, but also more information so that we can generate a meaningful
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//! error message.
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//!
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//! Having a catalog of all the different reasons an error can arise is
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//! also useful for other reasons, like cross-referencing FAQs etc, though
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//! we are not really taking advantage of this yet.
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//!
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//! # Region Inference
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//!
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//! Region inference is particularly tricky because it always succeeds "in
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//! the moment" and simply registers a constraint. Then, at the end, we
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//! can compute the full graph and report errors, so we need to be able to
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//! store and later report what gave rise to the conflicting constraints.
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//!
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//! # Subtype Trace
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//!
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//! Determining whether `T1 <: T2` often involves a number of subtypes and
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//! subconstraints along the way. A "TypeTrace" is an extended version
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//! of an origin that traces the types and other values that were being
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//! compared. It is not necessarily comprehensive (in fact, at the time of
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//! this writing it only tracks the root values being compared) but I'd
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//! like to extend it to include significant "waypoints". For example, if
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//! you are comparing `(T1, T2) <: (T3, T4)`, and the problem is that `T2
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//! <: T4` fails, I'd like the trace to include enough information to say
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//! "in the 2nd element of the tuple". Similarly, failures when comparing
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//! arguments or return types in fn types should be able to cite the
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//! specific position, etc.
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//!
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//! # Reality vs plan
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//!
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//! Of course, there is still a LOT of code in typeck that has yet to be
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//! ported to this system, and which relies on string concatenation at the
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//! time of error detection.
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use super::lexical_region_resolve::RegionResolutionError;
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use super::region_constraints::GenericKind;
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use super::{InferCtxt, RegionVariableOrigin, SubregionOrigin, TypeTrace, ValuePairs};
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use crate::infer::{self, SuppressRegionErrors};
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use crate::hir;
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use crate::hir::def_id::DefId;
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use crate::hir::Node;
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use crate::middle::region;
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use crate::traits::{ObligationCause, ObligationCauseCode};
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use crate::ty::error::TypeError;
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use crate::ty::{self, subst::{Subst, SubstsRef}, Region, Ty, TyCtxt, TypeFoldable};
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use errors::{Applicability, DiagnosticBuilder, DiagnosticStyledString};
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use std::{cmp, fmt};
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use syntax_pos::{Pos, Span};
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mod note;
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mod need_type_info;
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pub mod nice_region_error;
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impl<'tcx> TyCtxt<'tcx> {
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pub fn note_and_explain_region(
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self,
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region_scope_tree: ®ion::ScopeTree,
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err: &mut DiagnosticBuilder<'_>,
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prefix: &str,
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region: ty::Region<'tcx>,
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suffix: &str,
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) {
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let (description, span) = match *region {
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ty::ReScope(scope) => {
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let new_string;
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let unknown_scope = || {
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format!(
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"{}unknown scope: {:?}{}. Please report a bug.",
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prefix, scope, suffix
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)
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};
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let span = scope.span(self, region_scope_tree);
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let tag = match self.hir().find(scope.node_id(self, region_scope_tree)) {
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Some(Node::Block(_)) => "block",
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Some(Node::Expr(expr)) => match expr.node {
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hir::ExprKind::Call(..) => "call",
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hir::ExprKind::MethodCall(..) => "method call",
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hir::ExprKind::Match(.., hir::MatchSource::IfLetDesugar { .. }) => "if let",
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hir::ExprKind::Match(.., hir::MatchSource::WhileLetDesugar) => "while let",
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hir::ExprKind::Match(.., hir::MatchSource::ForLoopDesugar) => "for",
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hir::ExprKind::Match(..) => "match",
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_ => "expression",
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},
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Some(Node::Stmt(_)) => "statement",
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Some(Node::Item(it)) => Self::item_scope_tag(&it),
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Some(Node::TraitItem(it)) => Self::trait_item_scope_tag(&it),
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Some(Node::ImplItem(it)) => Self::impl_item_scope_tag(&it),
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Some(_) | None => {
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err.span_note(span, &unknown_scope());
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return;
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}
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};
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let scope_decorated_tag = match scope.data {
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region::ScopeData::Node => tag,
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region::ScopeData::CallSite => "scope of call-site for function",
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region::ScopeData::Arguments => "scope of function body",
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region::ScopeData::Destruction => {
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new_string = format!("destruction scope surrounding {}", tag);
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&new_string[..]
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}
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region::ScopeData::Remainder(first_statement_index) => {
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new_string = format!(
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"block suffix following statement {}",
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first_statement_index.index()
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);
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&new_string[..]
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}
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};
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self.explain_span(scope_decorated_tag, span)
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}
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ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReStatic => {
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self.msg_span_from_free_region(region)
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}
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ty::ReEmpty => ("the empty lifetime".to_owned(), None),
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ty::RePlaceholder(_) => (format!("any other region"), None),
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// FIXME(#13998) RePlaceholder should probably print like
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// ReFree rather than dumping Debug output on the user.
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//
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// We shouldn't really be having unification failures with ReVar
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// and ReLateBound though.
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ty::ReVar(_) | ty::ReLateBound(..) | ty::ReErased => {
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(format!("lifetime {:?}", region), None)
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}
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// We shouldn't encounter an error message with ReClosureBound.
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ty::ReClosureBound(..) => {
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bug!("encountered unexpected ReClosureBound: {:?}", region,);
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}
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};
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TyCtxt::emit_msg_span(err, prefix, description, span, suffix);
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}
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pub fn note_and_explain_free_region(
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self,
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err: &mut DiagnosticBuilder<'_>,
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prefix: &str,
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region: ty::Region<'tcx>,
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suffix: &str,
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) {
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let (description, span) = self.msg_span_from_free_region(region);
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TyCtxt::emit_msg_span(err, prefix, description, span, suffix);
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}
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fn msg_span_from_free_region(self, region: ty::Region<'tcx>) -> (String, Option<Span>) {
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match *region {
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ty::ReEarlyBound(_) | ty::ReFree(_) => {
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self.msg_span_from_early_bound_and_free_regions(region)
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}
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ty::ReStatic => ("the static lifetime".to_owned(), None),
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ty::ReEmpty => ("an empty lifetime".to_owned(), None),
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_ => bug!("{:?}", region),
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}
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}
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fn msg_span_from_early_bound_and_free_regions(
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self,
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region: ty::Region<'tcx>,
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) -> (String, Option<Span>) {
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let cm = self.sess.source_map();
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let scope = region.free_region_binding_scope(self);
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let node = self.hir().as_local_hir_id(scope).unwrap_or(hir::DUMMY_HIR_ID);
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let tag = match self.hir().find_by_hir_id(node) {
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Some(Node::Block(_)) | Some(Node::Expr(_)) => "body",
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Some(Node::Item(it)) => Self::item_scope_tag(&it),
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Some(Node::TraitItem(it)) => Self::trait_item_scope_tag(&it),
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Some(Node::ImplItem(it)) => Self::impl_item_scope_tag(&it),
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_ => unreachable!(),
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};
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let (prefix, span) = match *region {
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ty::ReEarlyBound(ref br) => {
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let mut sp = cm.def_span(self.hir().span_by_hir_id(node));
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if let Some(param) = self.hir()
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.get_generics(scope)
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.and_then(|generics| generics.get_named(br.name))
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{
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sp = param.span;
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}
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(format!("the lifetime {} as defined on", br.name), sp)
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}
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ty::ReFree(ty::FreeRegion {
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bound_region: ty::BoundRegion::BrNamed(_, name),
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..
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}) => {
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let mut sp = cm.def_span(self.hir().span_by_hir_id(node));
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if let Some(param) = self.hir()
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.get_generics(scope)
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.and_then(|generics| generics.get_named(name))
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{
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sp = param.span;
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}
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(format!("the lifetime {} as defined on", name), sp)
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}
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ty::ReFree(ref fr) => match fr.bound_region {
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ty::BrAnon(idx) => (
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format!("the anonymous lifetime #{} defined on", idx + 1),
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self.hir().span_by_hir_id(node),
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),
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_ => (
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format!("the lifetime {} as defined on", region),
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cm.def_span(self.hir().span_by_hir_id(node)),
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),
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},
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_ => bug!(),
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};
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let (msg, opt_span) = self.explain_span(tag, span);
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(format!("{} {}", prefix, msg), opt_span)
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}
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fn emit_msg_span(
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err: &mut DiagnosticBuilder<'_>,
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prefix: &str,
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description: String,
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span: Option<Span>,
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suffix: &str,
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) {
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let message = format!("{}{}{}", prefix, description, suffix);
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if let Some(span) = span {
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err.span_note(span, &message);
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} else {
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err.note(&message);
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}
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}
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fn item_scope_tag(item: &hir::Item) -> &'static str {
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match item.node {
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hir::ItemKind::Impl(..) => "impl",
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hir::ItemKind::Struct(..) => "struct",
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hir::ItemKind::Union(..) => "union",
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hir::ItemKind::Enum(..) => "enum",
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hir::ItemKind::Trait(..) => "trait",
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hir::ItemKind::Fn(..) => "function body",
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_ => "item",
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}
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}
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fn trait_item_scope_tag(item: &hir::TraitItem) -> &'static str {
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match item.node {
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hir::TraitItemKind::Method(..) => "method body",
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hir::TraitItemKind::Const(..) | hir::TraitItemKind::Type(..) => "associated item",
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}
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}
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fn impl_item_scope_tag(item: &hir::ImplItem) -> &'static str {
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match item.node {
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hir::ImplItemKind::Method(..) => "method body",
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hir::ImplItemKind::Const(..)
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| hir::ImplItemKind::Existential(..)
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| hir::ImplItemKind::Type(..) => "associated item",
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}
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}
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fn explain_span(self, heading: &str, span: Span) -> (String, Option<Span>) {
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let lo = self.sess.source_map().lookup_char_pos(span.lo());
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(
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format!("the {} at {}:{}", heading, lo.line, lo.col.to_usize() + 1),
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Some(span),
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)
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}
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}
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impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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pub fn report_region_errors(
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&self,
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region_scope_tree: ®ion::ScopeTree,
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errors: &Vec<RegionResolutionError<'tcx>>,
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suppress: SuppressRegionErrors,
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) {
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debug!(
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"report_region_errors(): {} errors to start, suppress = {:?}",
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errors.len(),
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suppress
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);
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if suppress.suppressed() {
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return;
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}
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// try to pre-process the errors, which will group some of them
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// together into a `ProcessedErrors` group:
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let errors = self.process_errors(errors);
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debug!(
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"report_region_errors: {} errors after preprocessing",
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errors.len()
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);
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for error in errors {
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debug!("report_region_errors: error = {:?}", error);
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if !self.try_report_nice_region_error(&error) {
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match error.clone() {
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// These errors could indicate all manner of different
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// problems with many different solutions. Rather
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// than generate a "one size fits all" error, what we
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// attempt to do is go through a number of specific
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// scenarios and try to find the best way to present
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// the error. If all of these fails, we fall back to a rather
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// general bit of code that displays the error information
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RegionResolutionError::ConcreteFailure(origin, sub, sup) => {
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if sub.is_placeholder() || sup.is_placeholder() {
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self.report_placeholder_failure(region_scope_tree, origin, sub, sup)
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.emit();
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} else {
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self.report_concrete_failure(region_scope_tree, origin, sub, sup)
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.emit();
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}
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}
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RegionResolutionError::GenericBoundFailure(origin, param_ty, sub) => {
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self.report_generic_bound_failure(
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region_scope_tree,
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origin.span(),
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Some(origin),
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param_ty,
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sub,
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);
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}
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RegionResolutionError::SubSupConflict(
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_,
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var_origin,
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sub_origin,
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sub_r,
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sup_origin,
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sup_r,
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) => {
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if sub_r.is_placeholder() {
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self.report_placeholder_failure(
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region_scope_tree,
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sub_origin,
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sub_r,
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sup_r,
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)
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.emit();
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} else if sup_r.is_placeholder() {
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self.report_placeholder_failure(
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region_scope_tree,
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sup_origin,
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sub_r,
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sup_r,
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)
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.emit();
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} else {
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self.report_sub_sup_conflict(
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region_scope_tree,
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var_origin,
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sub_origin,
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sub_r,
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sup_origin,
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sup_r,
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);
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}
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}
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}
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}
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}
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}
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|
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// This method goes through all the errors and try to group certain types
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// of error together, for the purpose of suggesting explicit lifetime
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// parameters to the user. This is done so that we can have a more
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// complete view of what lifetimes should be the same.
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|
// If the return value is an empty vector, it means that processing
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// failed (so the return value of this method should not be used).
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//
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// The method also attempts to weed out messages that seem like
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// duplicates that will be unhelpful to the end-user. But
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// obviously it never weeds out ALL errors.
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fn process_errors(
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&self,
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errors: &Vec<RegionResolutionError<'tcx>>,
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) -> Vec<RegionResolutionError<'tcx>> {
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debug!("process_errors()");
|
|
|
|
// We want to avoid reporting generic-bound failures if we can
|
|
// avoid it: these have a very high rate of being unhelpful in
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// practice. This is because they are basically secondary
|
|
// checks that test the state of the region graph after the
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|
// rest of inference is done, and the other kinds of errors
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|
// indicate that the region constraint graph is internally
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|
// inconsistent, so these test results are likely to be
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|
// meaningless.
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|
//
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|
// Therefore, we filter them out of the list unless they are
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|
// the only thing in the list.
|
|
|
|
let is_bound_failure = |e: &RegionResolutionError<'tcx>| match *e {
|
|
RegionResolutionError::GenericBoundFailure(..) => true,
|
|
RegionResolutionError::ConcreteFailure(..)
|
|
| RegionResolutionError::SubSupConflict(..) => false,
|
|
};
|
|
|
|
let mut errors = if errors.iter().all(|e| is_bound_failure(e)) {
|
|
errors.clone()
|
|
} else {
|
|
errors
|
|
.iter()
|
|
.filter(|&e| !is_bound_failure(e))
|
|
.cloned()
|
|
.collect()
|
|
};
|
|
|
|
// sort the errors by span, for better error message stability.
|
|
errors.sort_by_key(|u| match *u {
|
|
RegionResolutionError::ConcreteFailure(ref sro, _, _) => sro.span(),
|
|
RegionResolutionError::GenericBoundFailure(ref sro, _, _) => sro.span(),
|
|
RegionResolutionError::SubSupConflict(_, ref rvo, _, _, _, _) => rvo.span(),
|
|
});
|
|
errors
|
|
}
|
|
|
|
/// Adds a note if the types come from similarly named crates
|
|
fn check_and_note_conflicting_crates(
|
|
&self,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
terr: &TypeError<'tcx>,
|
|
sp: Span,
|
|
) {
|
|
use hir::def_id::CrateNum;
|
|
use hir::map::DisambiguatedDefPathData;
|
|
use ty::print::Printer;
|
|
use ty::subst::Kind;
|
|
|
|
struct AbsolutePathPrinter<'tcx> {
|
|
tcx: TyCtxt<'tcx>,
|
|
}
|
|
|
|
struct NonTrivialPath;
|
|
|
|
impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
|
|
type Error = NonTrivialPath;
|
|
|
|
type Path = Vec<String>;
|
|
type Region = !;
|
|
type Type = !;
|
|
type DynExistential = !;
|
|
type Const = !;
|
|
|
|
fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
|
|
self.tcx
|
|
}
|
|
|
|
fn print_region(
|
|
self,
|
|
_region: ty::Region<'_>,
|
|
) -> Result<Self::Region, Self::Error> {
|
|
Err(NonTrivialPath)
|
|
}
|
|
|
|
fn print_type(
|
|
self,
|
|
_ty: Ty<'tcx>,
|
|
) -> Result<Self::Type, Self::Error> {
|
|
Err(NonTrivialPath)
|
|
}
|
|
|
|
fn print_dyn_existential(
|
|
self,
|
|
_predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
|
|
) -> Result<Self::DynExistential, Self::Error> {
|
|
Err(NonTrivialPath)
|
|
}
|
|
|
|
fn print_const(
|
|
self,
|
|
_ct: &'tcx ty::Const<'tcx>,
|
|
) -> Result<Self::Const, Self::Error> {
|
|
Err(NonTrivialPath)
|
|
}
|
|
|
|
fn path_crate(
|
|
self,
|
|
cnum: CrateNum,
|
|
) -> Result<Self::Path, Self::Error> {
|
|
Ok(vec![self.tcx.original_crate_name(cnum).to_string()])
|
|
}
|
|
fn path_qualified(
|
|
self,
|
|
_self_ty: Ty<'tcx>,
|
|
_trait_ref: Option<ty::TraitRef<'tcx>>,
|
|
) -> Result<Self::Path, Self::Error> {
|
|
Err(NonTrivialPath)
|
|
}
|
|
|
|
fn path_append_impl(
|
|
self,
|
|
_print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
|
|
_disambiguated_data: &DisambiguatedDefPathData,
|
|
_self_ty: Ty<'tcx>,
|
|
_trait_ref: Option<ty::TraitRef<'tcx>>,
|
|
) -> Result<Self::Path, Self::Error> {
|
|
Err(NonTrivialPath)
|
|
}
|
|
fn path_append(
|
|
self,
|
|
print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
|
|
disambiguated_data: &DisambiguatedDefPathData,
|
|
) -> Result<Self::Path, Self::Error> {
|
|
let mut path = print_prefix(self)?;
|
|
path.push(disambiguated_data.data.as_interned_str().to_string());
|
|
Ok(path)
|
|
}
|
|
fn path_generic_args(
|
|
self,
|
|
print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
|
|
_args: &[Kind<'tcx>],
|
|
) -> Result<Self::Path, Self::Error> {
|
|
print_prefix(self)
|
|
}
|
|
}
|
|
|
|
let report_path_match = |err: &mut DiagnosticBuilder<'_>, did1: DefId, did2: DefId| {
|
|
// Only external crates, if either is from a local
|
|
// module we could have false positives
|
|
if !(did1.is_local() || did2.is_local()) && did1.krate != did2.krate {
|
|
let abs_path = |def_id| {
|
|
AbsolutePathPrinter { tcx: self.tcx }
|
|
.print_def_path(def_id, &[])
|
|
};
|
|
|
|
// We compare strings because DefPath can be different
|
|
// for imported and non-imported crates
|
|
let same_path = || -> Result<_, NonTrivialPath> {
|
|
Ok(
|
|
self.tcx.def_path_str(did1) == self.tcx.def_path_str(did2) ||
|
|
abs_path(did1)? == abs_path(did2)?
|
|
)
|
|
};
|
|
if same_path().unwrap_or(false) {
|
|
let crate_name = self.tcx.crate_name(did1.krate);
|
|
err.span_note(
|
|
sp,
|
|
&format!(
|
|
"Perhaps two different versions \
|
|
of crate `{}` are being used?",
|
|
crate_name
|
|
),
|
|
);
|
|
}
|
|
}
|
|
};
|
|
match *terr {
|
|
TypeError::Sorts(ref exp_found) => {
|
|
// if they are both "path types", there's a chance of ambiguity
|
|
// due to different versions of the same crate
|
|
if let (&ty::Adt(exp_adt, _), &ty::Adt(found_adt, _))
|
|
= (&exp_found.expected.sty, &exp_found.found.sty)
|
|
{
|
|
report_path_match(err, exp_adt.did, found_adt.did);
|
|
}
|
|
}
|
|
TypeError::Traits(ref exp_found) => {
|
|
report_path_match(err, exp_found.expected, exp_found.found);
|
|
}
|
|
_ => (), // FIXME(#22750) handle traits and stuff
|
|
}
|
|
}
|
|
|
|
fn note_error_origin(
|
|
&self,
|
|
err: &mut DiagnosticBuilder<'tcx>,
|
|
cause: &ObligationCause<'tcx>,
|
|
exp_found: Option<ty::error::ExpectedFound<Ty<'tcx>>>,
|
|
) {
|
|
match cause.code {
|
|
ObligationCauseCode::MatchExpressionArmPattern { span, ty } => {
|
|
if ty.is_suggestable() { // don't show type `_`
|
|
err.span_label(span, format!("this match expression has type `{}`", ty));
|
|
}
|
|
if let Some(ty::error::ExpectedFound { found, .. }) = exp_found {
|
|
if ty.is_box() && ty.boxed_ty() == found {
|
|
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
|
|
err.span_suggestion(
|
|
span,
|
|
"consider dereferencing the boxed value",
|
|
format!("*{}", snippet),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
ObligationCauseCode::MatchExpressionArm {
|
|
source,
|
|
ref prior_arms,
|
|
last_ty,
|
|
discrim_hir_id,
|
|
..
|
|
} => match source {
|
|
hir::MatchSource::IfLetDesugar { .. } => {
|
|
let msg = "`if let` arms have incompatible types";
|
|
err.span_label(cause.span, msg);
|
|
}
|
|
hir::MatchSource::TryDesugar => {
|
|
if let Some(ty::error::ExpectedFound { expected, .. }) = exp_found {
|
|
let discrim_expr = self.tcx.hir().expect_expr_by_hir_id(discrim_hir_id);
|
|
let discrim_ty = if let hir::ExprKind::Call(_, args) = &discrim_expr.node {
|
|
let arg_expr = args.first().expect("try desugaring call w/out arg");
|
|
self.in_progress_tables.and_then(|tables| {
|
|
tables.borrow().expr_ty_opt(arg_expr)
|
|
})
|
|
} else {
|
|
bug!("try desugaring w/out call expr as discriminant");
|
|
};
|
|
|
|
match discrim_ty {
|
|
Some(ty) if expected == ty => {
|
|
let source_map = self.tcx.sess.source_map();
|
|
err.span_suggestion(
|
|
source_map.end_point(cause.span),
|
|
"try removing this `?`",
|
|
"".to_string(),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
},
|
|
_ => {},
|
|
}
|
|
}
|
|
}
|
|
_ => {
|
|
let msg = "`match` arms have incompatible types";
|
|
err.span_label(cause.span, msg);
|
|
if prior_arms.len() <= 4 {
|
|
for sp in prior_arms {
|
|
err.span_label(*sp, format!(
|
|
"this is found to be of type `{}`",
|
|
self.resolve_vars_if_possible(&last_ty),
|
|
));
|
|
}
|
|
} else if let Some(sp) = prior_arms.last() {
|
|
err.span_label(*sp, format!(
|
|
"this and all prior arms are found to be of type `{}`", last_ty,
|
|
));
|
|
}
|
|
}
|
|
},
|
|
ObligationCauseCode::IfExpression { then, outer, semicolon } => {
|
|
err.span_label(then, "expected because of this");
|
|
outer.map(|sp| err.span_label(sp, "if and else have incompatible types"));
|
|
if let Some(sp) = semicolon {
|
|
err.span_suggestion_short(
|
|
sp,
|
|
"consider removing this semicolon",
|
|
String::new(),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
_ => (),
|
|
}
|
|
}
|
|
|
|
/// Given that `other_ty` is the same as a type argument for `name` in `sub`, populate `value`
|
|
/// highlighting `name` and every type argument that isn't at `pos` (which is `other_ty`), and
|
|
/// populate `other_value` with `other_ty`.
|
|
///
|
|
/// ```text
|
|
/// Foo<Bar<Qux>>
|
|
/// ^^^^--------^ this is highlighted
|
|
/// | |
|
|
/// | this type argument is exactly the same as the other type, not highlighted
|
|
/// this is highlighted
|
|
/// Bar<Qux>
|
|
/// -------- this type is the same as a type argument in the other type, not highlighted
|
|
/// ```
|
|
fn highlight_outer(
|
|
&self,
|
|
value: &mut DiagnosticStyledString,
|
|
other_value: &mut DiagnosticStyledString,
|
|
name: String,
|
|
sub: ty::subst::SubstsRef<'tcx>,
|
|
pos: usize,
|
|
other_ty: Ty<'tcx>,
|
|
) {
|
|
// `value` and `other_value` hold two incomplete type representation for display.
|
|
// `name` is the path of both types being compared. `sub`
|
|
value.push_highlighted(name);
|
|
let len = sub.len();
|
|
if len > 0 {
|
|
value.push_highlighted("<");
|
|
}
|
|
|
|
// Output the lifetimes for the first type
|
|
let lifetimes = sub.regions()
|
|
.map(|lifetime| {
|
|
let s = lifetime.to_string();
|
|
if s.is_empty() {
|
|
"'_".to_string()
|
|
} else {
|
|
s
|
|
}
|
|
})
|
|
.collect::<Vec<_>>()
|
|
.join(", ");
|
|
if !lifetimes.is_empty() {
|
|
if sub.regions().count() < len {
|
|
value.push_normal(lifetimes + &", ");
|
|
} else {
|
|
value.push_normal(lifetimes);
|
|
}
|
|
}
|
|
|
|
// Highlight all the type arguments that aren't at `pos` and compare the type argument at
|
|
// `pos` and `other_ty`.
|
|
for (i, type_arg) in sub.types().enumerate() {
|
|
if i == pos {
|
|
let values = self.cmp(type_arg, other_ty);
|
|
value.0.extend((values.0).0);
|
|
other_value.0.extend((values.1).0);
|
|
} else {
|
|
value.push_highlighted(type_arg.to_string());
|
|
}
|
|
|
|
if len > 0 && i != len - 1 {
|
|
value.push_normal(", ");
|
|
}
|
|
//self.push_comma(&mut value, &mut other_value, len, i);
|
|
}
|
|
if len > 0 {
|
|
value.push_highlighted(">");
|
|
}
|
|
}
|
|
|
|
/// If `other_ty` is the same as a type argument present in `sub`, highlight `path` in `t1_out`,
|
|
/// as that is the difference to the other type.
|
|
///
|
|
/// For the following code:
|
|
///
|
|
/// ```norun
|
|
/// let x: Foo<Bar<Qux>> = foo::<Bar<Qux>>();
|
|
/// ```
|
|
///
|
|
/// The type error output will behave in the following way:
|
|
///
|
|
/// ```text
|
|
/// Foo<Bar<Qux>>
|
|
/// ^^^^--------^ this is highlighted
|
|
/// | |
|
|
/// | this type argument is exactly the same as the other type, not highlighted
|
|
/// this is highlighted
|
|
/// Bar<Qux>
|
|
/// -------- this type is the same as a type argument in the other type, not highlighted
|
|
/// ```
|
|
fn cmp_type_arg(
|
|
&self,
|
|
mut t1_out: &mut DiagnosticStyledString,
|
|
mut t2_out: &mut DiagnosticStyledString,
|
|
path: String,
|
|
sub: ty::subst::SubstsRef<'tcx>,
|
|
other_path: String,
|
|
other_ty: Ty<'tcx>,
|
|
) -> Option<()> {
|
|
for (i, ta) in sub.types().enumerate() {
|
|
if ta == other_ty {
|
|
self.highlight_outer(&mut t1_out, &mut t2_out, path, sub, i, &other_ty);
|
|
return Some(());
|
|
}
|
|
if let &ty::Adt(def, _) = &ta.sty {
|
|
let path_ = self.tcx.def_path_str(def.did.clone());
|
|
if path_ == other_path {
|
|
self.highlight_outer(&mut t1_out, &mut t2_out, path, sub, i, &other_ty);
|
|
return Some(());
|
|
}
|
|
}
|
|
}
|
|
None
|
|
}
|
|
|
|
/// Adds a `,` to the type representation only if it is appropriate.
|
|
fn push_comma(
|
|
&self,
|
|
value: &mut DiagnosticStyledString,
|
|
other_value: &mut DiagnosticStyledString,
|
|
len: usize,
|
|
pos: usize,
|
|
) {
|
|
if len > 0 && pos != len - 1 {
|
|
value.push_normal(", ");
|
|
other_value.push_normal(", ");
|
|
}
|
|
}
|
|
|
|
/// For generic types with parameters with defaults, remove the parameters corresponding to
|
|
/// the defaults. This repeats a lot of the logic found in `ty::print::pretty`.
|
|
fn strip_generic_default_params(
|
|
&self,
|
|
def_id: DefId,
|
|
substs: ty::subst::SubstsRef<'tcx>,
|
|
) -> SubstsRef<'tcx> {
|
|
let generics = self.tcx.generics_of(def_id);
|
|
let mut num_supplied_defaults = 0;
|
|
let mut type_params = generics.params.iter().rev().filter_map(|param| match param.kind {
|
|
ty::GenericParamDefKind::Lifetime => None,
|
|
ty::GenericParamDefKind::Type { has_default, .. } => Some((param.def_id, has_default)),
|
|
ty::GenericParamDefKind::Const => None, // FIXME(const_generics:defaults)
|
|
}).peekable();
|
|
let has_default = {
|
|
let has_default = type_params.peek().map(|(_, has_default)| has_default);
|
|
*has_default.unwrap_or(&false)
|
|
};
|
|
if has_default {
|
|
let types = substs.types().rev();
|
|
for ((def_id, has_default), actual) in type_params.zip(types) {
|
|
if !has_default {
|
|
break;
|
|
}
|
|
if self.tcx.type_of(def_id).subst(self.tcx, substs) != actual {
|
|
break;
|
|
}
|
|
num_supplied_defaults += 1;
|
|
}
|
|
}
|
|
let len = generics.params.len();
|
|
let mut generics = generics.clone();
|
|
generics.params.truncate(len - num_supplied_defaults);
|
|
substs.truncate_to(self.tcx, &generics)
|
|
}
|
|
|
|
/// Compares two given types, eliding parts that are the same between them and highlighting
|
|
/// relevant differences, and return two representation of those types for highlighted printing.
|
|
fn cmp(&self, t1: Ty<'tcx>, t2: Ty<'tcx>) -> (DiagnosticStyledString, DiagnosticStyledString) {
|
|
fn equals<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
|
|
match (&a.sty, &b.sty) {
|
|
(a, b) if *a == *b => true,
|
|
(&ty::Int(_), &ty::Infer(ty::InferTy::IntVar(_)))
|
|
| (&ty::Infer(ty::InferTy::IntVar(_)), &ty::Int(_))
|
|
| (&ty::Infer(ty::InferTy::IntVar(_)), &ty::Infer(ty::InferTy::IntVar(_)))
|
|
| (&ty::Float(_), &ty::Infer(ty::InferTy::FloatVar(_)))
|
|
| (&ty::Infer(ty::InferTy::FloatVar(_)), &ty::Float(_))
|
|
| (&ty::Infer(ty::InferTy::FloatVar(_)), &ty::Infer(ty::InferTy::FloatVar(_))) => {
|
|
true
|
|
}
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
fn push_ty_ref<'tcx>(
|
|
r: &ty::Region<'tcx>,
|
|
ty: Ty<'tcx>,
|
|
mutbl: hir::Mutability,
|
|
s: &mut DiagnosticStyledString,
|
|
) {
|
|
let mut r = r.to_string();
|
|
if r == "'_" {
|
|
r.clear();
|
|
} else {
|
|
r.push(' ');
|
|
}
|
|
s.push_highlighted(format!(
|
|
"&{}{}",
|
|
r,
|
|
if mutbl == hir::MutMutable { "mut " } else { "" }
|
|
));
|
|
s.push_normal(ty.to_string());
|
|
}
|
|
|
|
match (&t1.sty, &t2.sty) {
|
|
(&ty::Adt(def1, sub1), &ty::Adt(def2, sub2)) => {
|
|
let sub_no_defaults_1 = self.strip_generic_default_params(def1.did, sub1);
|
|
let sub_no_defaults_2 = self.strip_generic_default_params(def2.did, sub2);
|
|
let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new());
|
|
let path1 = self.tcx.def_path_str(def1.did.clone());
|
|
let path2 = self.tcx.def_path_str(def2.did.clone());
|
|
if def1.did == def2.did {
|
|
// Easy case. Replace same types with `_` to shorten the output and highlight
|
|
// the differing ones.
|
|
// let x: Foo<Bar, Qux> = y::<Foo<Quz, Qux>>();
|
|
// Foo<Bar, _>
|
|
// Foo<Quz, _>
|
|
// --- ^ type argument elided
|
|
// |
|
|
// highlighted in output
|
|
values.0.push_normal(path1);
|
|
values.1.push_normal(path2);
|
|
|
|
// Avoid printing out default generic parameters that are common to both
|
|
// types.
|
|
let len1 = sub_no_defaults_1.len();
|
|
let len2 = sub_no_defaults_2.len();
|
|
let common_len = cmp::min(len1, len2);
|
|
let remainder1: Vec<_> = sub1.types().skip(common_len).collect();
|
|
let remainder2: Vec<_> = sub2.types().skip(common_len).collect();
|
|
let common_default_params = remainder1
|
|
.iter()
|
|
.rev()
|
|
.zip(remainder2.iter().rev())
|
|
.filter(|(a, b)| a == b)
|
|
.count();
|
|
let len = sub1.len() - common_default_params;
|
|
|
|
// Only draw `<...>` if there're lifetime/type arguments.
|
|
if len > 0 {
|
|
values.0.push_normal("<");
|
|
values.1.push_normal("<");
|
|
}
|
|
|
|
fn lifetime_display(lifetime: Region<'_>) -> String {
|
|
let s = lifetime.to_string();
|
|
if s.is_empty() {
|
|
"'_".to_string()
|
|
} else {
|
|
s
|
|
}
|
|
}
|
|
// At one point we'd like to elide all lifetimes here, they are irrelevant for
|
|
// all diagnostics that use this output
|
|
//
|
|
// Foo<'x, '_, Bar>
|
|
// Foo<'y, '_, Qux>
|
|
// ^^ ^^ --- type arguments are not elided
|
|
// | |
|
|
// | elided as they were the same
|
|
// not elided, they were different, but irrelevant
|
|
let lifetimes = sub1.regions().zip(sub2.regions());
|
|
for (i, lifetimes) in lifetimes.enumerate() {
|
|
let l1 = lifetime_display(lifetimes.0);
|
|
let l2 = lifetime_display(lifetimes.1);
|
|
if l1 == l2 {
|
|
values.0.push_normal("'_");
|
|
values.1.push_normal("'_");
|
|
} else {
|
|
values.0.push_highlighted(l1);
|
|
values.1.push_highlighted(l2);
|
|
}
|
|
self.push_comma(&mut values.0, &mut values.1, len, i);
|
|
}
|
|
|
|
// We're comparing two types with the same path, so we compare the type
|
|
// arguments for both. If they are the same, do not highlight and elide from the
|
|
// output.
|
|
// Foo<_, Bar>
|
|
// Foo<_, Qux>
|
|
// ^ elided type as this type argument was the same in both sides
|
|
let type_arguments = sub1.types().zip(sub2.types());
|
|
let regions_len = sub1.regions().count();
|
|
for (i, (ta1, ta2)) in type_arguments.take(len).enumerate() {
|
|
let i = i + regions_len;
|
|
if ta1 == ta2 {
|
|
values.0.push_normal("_");
|
|
values.1.push_normal("_");
|
|
} else {
|
|
let (x1, x2) = self.cmp(ta1, ta2);
|
|
(values.0).0.extend(x1.0);
|
|
(values.1).0.extend(x2.0);
|
|
}
|
|
self.push_comma(&mut values.0, &mut values.1, len, i);
|
|
}
|
|
|
|
// Close the type argument bracket.
|
|
// Only draw `<...>` if there're lifetime/type arguments.
|
|
if len > 0 {
|
|
values.0.push_normal(">");
|
|
values.1.push_normal(">");
|
|
}
|
|
values
|
|
} else {
|
|
// Check for case:
|
|
// let x: Foo<Bar<Qux> = foo::<Bar<Qux>>();
|
|
// Foo<Bar<Qux>
|
|
// ------- this type argument is exactly the same as the other type
|
|
// Bar<Qux>
|
|
if self.cmp_type_arg(
|
|
&mut values.0,
|
|
&mut values.1,
|
|
path1.clone(),
|
|
sub_no_defaults_1,
|
|
path2.clone(),
|
|
&t2,
|
|
).is_some()
|
|
{
|
|
return values;
|
|
}
|
|
// Check for case:
|
|
// let x: Bar<Qux> = y:<Foo<Bar<Qux>>>();
|
|
// Bar<Qux>
|
|
// Foo<Bar<Qux>>
|
|
// ------- this type argument is exactly the same as the other type
|
|
if self.cmp_type_arg(
|
|
&mut values.1,
|
|
&mut values.0,
|
|
path2,
|
|
sub_no_defaults_2,
|
|
path1,
|
|
&t1,
|
|
).is_some()
|
|
{
|
|
return values;
|
|
}
|
|
|
|
// We couldn't find anything in common, highlight everything.
|
|
// let x: Bar<Qux> = y::<Foo<Zar>>();
|
|
(
|
|
DiagnosticStyledString::highlighted(t1.to_string()),
|
|
DiagnosticStyledString::highlighted(t2.to_string()),
|
|
)
|
|
}
|
|
}
|
|
|
|
// When finding T != &T, highlight only the borrow
|
|
(&ty::Ref(r1, ref_ty1, mutbl1), _) if equals(&ref_ty1, &t2) => {
|
|
let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new());
|
|
push_ty_ref(&r1, ref_ty1, mutbl1, &mut values.0);
|
|
values.1.push_normal(t2.to_string());
|
|
values
|
|
}
|
|
(_, &ty::Ref(r2, ref_ty2, mutbl2)) if equals(&t1, &ref_ty2) => {
|
|
let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new());
|
|
values.0.push_normal(t1.to_string());
|
|
push_ty_ref(&r2, ref_ty2, mutbl2, &mut values.1);
|
|
values
|
|
}
|
|
|
|
// When encountering &T != &mut T, highlight only the borrow
|
|
(&ty::Ref(r1, ref_ty1, mutbl1), &ty::Ref(r2, ref_ty2, mutbl2))
|
|
if equals(&ref_ty1, &ref_ty2) =>
|
|
{
|
|
let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new());
|
|
push_ty_ref(&r1, ref_ty1, mutbl1, &mut values.0);
|
|
push_ty_ref(&r2, ref_ty2, mutbl2, &mut values.1);
|
|
values
|
|
}
|
|
|
|
_ => {
|
|
if t1 == t2 {
|
|
// The two types are the same, elide and don't highlight.
|
|
(
|
|
DiagnosticStyledString::normal("_"),
|
|
DiagnosticStyledString::normal("_"),
|
|
)
|
|
} else {
|
|
// We couldn't find anything in common, highlight everything.
|
|
(
|
|
DiagnosticStyledString::highlighted(t1.to_string()),
|
|
DiagnosticStyledString::highlighted(t2.to_string()),
|
|
)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn note_type_err(
|
|
&self,
|
|
diag: &mut DiagnosticBuilder<'tcx>,
|
|
cause: &ObligationCause<'tcx>,
|
|
secondary_span: Option<(Span, String)>,
|
|
mut values: Option<ValuePairs<'tcx>>,
|
|
terr: &TypeError<'tcx>,
|
|
) {
|
|
// For some types of errors, expected-found does not make
|
|
// sense, so just ignore the values we were given.
|
|
match terr {
|
|
TypeError::CyclicTy(_) => {
|
|
values = None;
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
let (expected_found, exp_found, is_simple_error) = match values {
|
|
None => (None, None, false),
|
|
Some(values) => {
|
|
let (is_simple_error, exp_found) = match values {
|
|
ValuePairs::Types(exp_found) => {
|
|
let is_simple_err =
|
|
exp_found.expected.is_primitive() && exp_found.found.is_primitive();
|
|
|
|
(is_simple_err, Some(exp_found))
|
|
}
|
|
_ => (false, None),
|
|
};
|
|
let vals = match self.values_str(&values) {
|
|
Some((expected, found)) => Some((expected, found)),
|
|
None => {
|
|
// Derived error. Cancel the emitter.
|
|
self.tcx.sess.diagnostic().cancel(diag);
|
|
return;
|
|
}
|
|
};
|
|
(vals, exp_found, is_simple_error)
|
|
}
|
|
};
|
|
|
|
let span = cause.span(self.tcx);
|
|
|
|
diag.span_label(span, terr.to_string());
|
|
if let Some((sp, msg)) = secondary_span {
|
|
diag.span_label(sp, msg);
|
|
}
|
|
|
|
if let Some((expected, found)) = expected_found {
|
|
match (terr, is_simple_error, expected == found) {
|
|
(&TypeError::Sorts(ref values), false, true) => {
|
|
diag.note_expected_found_extra(
|
|
&"type",
|
|
expected,
|
|
found,
|
|
&format!(" ({})", values.expected.sort_string(self.tcx)),
|
|
&format!(" ({})", values.found.sort_string(self.tcx)),
|
|
);
|
|
}
|
|
(_, false, _) => {
|
|
if let Some(exp_found) = exp_found {
|
|
let (def_id, ret_ty) = match exp_found.found.sty {
|
|
ty::FnDef(def, _) => {
|
|
(Some(def), Some(self.tcx.fn_sig(def).output()))
|
|
}
|
|
_ => (None, None),
|
|
};
|
|
|
|
let exp_is_struct = match exp_found.expected.sty {
|
|
ty::Adt(def, _) => def.is_struct(),
|
|
_ => false,
|
|
};
|
|
|
|
if let (Some(def_id), Some(ret_ty)) = (def_id, ret_ty) {
|
|
if exp_is_struct && &exp_found.expected == ret_ty.skip_binder() {
|
|
let message = format!(
|
|
"did you mean `{}(/* fields */)`?",
|
|
self.tcx.def_path_str(def_id)
|
|
);
|
|
diag.span_label(span, message);
|
|
}
|
|
}
|
|
self.suggest_as_ref_where_appropriate(span, &exp_found, diag);
|
|
}
|
|
|
|
diag.note_expected_found(&"type", expected, found);
|
|
}
|
|
_ => (),
|
|
}
|
|
}
|
|
|
|
self.check_and_note_conflicting_crates(diag, terr, span);
|
|
self.tcx.note_and_explain_type_err(diag, terr, span);
|
|
|
|
// It reads better to have the error origin as the final
|
|
// thing.
|
|
self.note_error_origin(diag, &cause, exp_found);
|
|
}
|
|
|
|
/// When encountering a case where `.as_ref()` on a `Result` or `Option` would be appropriate,
|
|
/// suggest it.
|
|
fn suggest_as_ref_where_appropriate(
|
|
&self,
|
|
span: Span,
|
|
exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
|
|
diag: &mut DiagnosticBuilder<'tcx>,
|
|
) {
|
|
match (&exp_found.expected.sty, &exp_found.found.sty) {
|
|
(ty::Adt(exp_def, exp_substs), ty::Ref(_, found_ty, _)) => {
|
|
if let ty::Adt(found_def, found_substs) = found_ty.sty {
|
|
let path_str = format!("{:?}", exp_def);
|
|
if exp_def == &found_def {
|
|
let opt_msg = "you can convert from `&Option<T>` to `Option<&T>` using \
|
|
`.as_ref()`";
|
|
let result_msg = "you can convert from `&Result<T, E>` to \
|
|
`Result<&T, &E>` using `.as_ref()`";
|
|
let have_as_ref = &[
|
|
("std::option::Option", opt_msg),
|
|
("core::option::Option", opt_msg),
|
|
("std::result::Result", result_msg),
|
|
("core::result::Result", result_msg),
|
|
];
|
|
if let Some(msg) = have_as_ref.iter()
|
|
.filter_map(|(path, msg)| if &path_str == path {
|
|
Some(msg)
|
|
} else {
|
|
None
|
|
}).next()
|
|
{
|
|
let mut show_suggestion = true;
|
|
for (exp_ty, found_ty) in exp_substs.types().zip(found_substs.types()) {
|
|
match exp_ty.sty {
|
|
ty::Ref(_, exp_ty, _) => {
|
|
match (&exp_ty.sty, &found_ty.sty) {
|
|
(_, ty::Param(_)) |
|
|
(_, ty::Infer(_)) |
|
|
(ty::Param(_), _) |
|
|
(ty::Infer(_), _) => {}
|
|
_ if ty::TyS::same_type(exp_ty, found_ty) => {}
|
|
_ => show_suggestion = false,
|
|
};
|
|
}
|
|
ty::Param(_) | ty::Infer(_) => {}
|
|
_ => show_suggestion = false,
|
|
}
|
|
}
|
|
if let (Ok(snippet), true) = (
|
|
self.tcx.sess.source_map().span_to_snippet(span),
|
|
show_suggestion,
|
|
) {
|
|
diag.span_suggestion(
|
|
span,
|
|
msg,
|
|
format!("{}.as_ref()", snippet),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
pub fn report_and_explain_type_error(
|
|
&self,
|
|
trace: TypeTrace<'tcx>,
|
|
terr: &TypeError<'tcx>,
|
|
) -> DiagnosticBuilder<'tcx> {
|
|
debug!(
|
|
"report_and_explain_type_error(trace={:?}, terr={:?})",
|
|
trace, terr
|
|
);
|
|
|
|
let span = trace.cause.span(self.tcx);
|
|
let failure_code = trace.cause.as_failure_code(terr);
|
|
let mut diag = match failure_code {
|
|
FailureCode::Error0317(failure_str) => {
|
|
struct_span_err!(self.tcx.sess, span, E0317, "{}", failure_str)
|
|
}
|
|
FailureCode::Error0580(failure_str) => {
|
|
struct_span_err!(self.tcx.sess, span, E0580, "{}", failure_str)
|
|
}
|
|
FailureCode::Error0308(failure_str) => {
|
|
struct_span_err!(self.tcx.sess, span, E0308, "{}", failure_str)
|
|
}
|
|
FailureCode::Error0644(failure_str) => {
|
|
struct_span_err!(self.tcx.sess, span, E0644, "{}", failure_str)
|
|
}
|
|
};
|
|
self.note_type_err(&mut diag, &trace.cause, None, Some(trace.values), terr);
|
|
diag
|
|
}
|
|
|
|
fn values_str(
|
|
&self,
|
|
values: &ValuePairs<'tcx>,
|
|
) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> {
|
|
match *values {
|
|
infer::Types(ref exp_found) => self.expected_found_str_ty(exp_found),
|
|
infer::Regions(ref exp_found) => self.expected_found_str(exp_found),
|
|
infer::Consts(ref exp_found) => self.expected_found_str(exp_found),
|
|
infer::TraitRefs(ref exp_found) => self.expected_found_str(exp_found),
|
|
infer::PolyTraitRefs(ref exp_found) => self.expected_found_str(exp_found),
|
|
}
|
|
}
|
|
|
|
fn expected_found_str_ty(
|
|
&self,
|
|
exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
|
|
) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> {
|
|
let exp_found = self.resolve_vars_if_possible(exp_found);
|
|
if exp_found.references_error() {
|
|
return None;
|
|
}
|
|
|
|
Some(self.cmp(exp_found.expected, exp_found.found))
|
|
}
|
|
|
|
/// Returns a string of the form "expected `{}`, found `{}`".
|
|
fn expected_found_str<T: fmt::Display + TypeFoldable<'tcx>>(
|
|
&self,
|
|
exp_found: &ty::error::ExpectedFound<T>,
|
|
) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> {
|
|
let exp_found = self.resolve_vars_if_possible(exp_found);
|
|
if exp_found.references_error() {
|
|
return None;
|
|
}
|
|
|
|
Some((
|
|
DiagnosticStyledString::highlighted(exp_found.expected.to_string()),
|
|
DiagnosticStyledString::highlighted(exp_found.found.to_string()),
|
|
))
|
|
}
|
|
|
|
pub fn report_generic_bound_failure(
|
|
&self,
|
|
region_scope_tree: ®ion::ScopeTree,
|
|
span: Span,
|
|
origin: Option<SubregionOrigin<'tcx>>,
|
|
bound_kind: GenericKind<'tcx>,
|
|
sub: Region<'tcx>,
|
|
) {
|
|
self.construct_generic_bound_failure(region_scope_tree, span, origin, bound_kind, sub)
|
|
.emit()
|
|
}
|
|
|
|
pub fn construct_generic_bound_failure(
|
|
&self,
|
|
region_scope_tree: ®ion::ScopeTree,
|
|
span: Span,
|
|
origin: Option<SubregionOrigin<'tcx>>,
|
|
bound_kind: GenericKind<'tcx>,
|
|
sub: Region<'tcx>,
|
|
) -> DiagnosticBuilder<'a> {
|
|
// Attempt to obtain the span of the parameter so we can
|
|
// suggest adding an explicit lifetime bound to it.
|
|
let type_param_span = match (self.in_progress_tables, bound_kind) {
|
|
(Some(ref table), GenericKind::Param(ref param)) => {
|
|
let table = table.borrow();
|
|
table.local_id_root.and_then(|did| {
|
|
let generics = self.tcx.generics_of(did);
|
|
// Account for the case where `did` corresponds to `Self`, which doesn't have
|
|
// the expected type argument.
|
|
if !param.is_self() {
|
|
let type_param = generics.type_param(param, self.tcx);
|
|
let hir = &self.tcx.hir();
|
|
hir.as_local_node_id(type_param.def_id).map(|id| {
|
|
// Get the `hir::Param` to verify whether it already has any bounds.
|
|
// We do this to avoid suggesting code that ends up as `T: 'a'b`,
|
|
// instead we suggest `T: 'a + 'b` in that case.
|
|
let mut has_bounds = false;
|
|
if let Node::GenericParam(ref param) = hir.get(id) {
|
|
has_bounds = !param.bounds.is_empty();
|
|
}
|
|
let sp = hir.span(id);
|
|
// `sp` only covers `T`, change it so that it covers
|
|
// `T:` when appropriate
|
|
let is_impl_trait = bound_kind.to_string().starts_with("impl ");
|
|
let sp = if has_bounds && !is_impl_trait {
|
|
sp.to(self.tcx
|
|
.sess
|
|
.source_map()
|
|
.next_point(self.tcx.sess.source_map().next_point(sp)))
|
|
} else {
|
|
sp
|
|
};
|
|
(sp, has_bounds, is_impl_trait)
|
|
})
|
|
} else {
|
|
None
|
|
}
|
|
})
|
|
}
|
|
_ => None,
|
|
};
|
|
|
|
let labeled_user_string = match bound_kind {
|
|
GenericKind::Param(ref p) => format!("the parameter type `{}`", p),
|
|
GenericKind::Projection(ref p) => format!("the associated type `{}`", p),
|
|
};
|
|
|
|
if let Some(SubregionOrigin::CompareImplMethodObligation {
|
|
span,
|
|
item_name,
|
|
impl_item_def_id,
|
|
trait_item_def_id,
|
|
}) = origin
|
|
{
|
|
return self.report_extra_impl_obligation(
|
|
span,
|
|
item_name,
|
|
impl_item_def_id,
|
|
trait_item_def_id,
|
|
&format!("`{}: {}`", bound_kind, sub),
|
|
);
|
|
}
|
|
|
|
fn binding_suggestion<'tcx, S: fmt::Display>(
|
|
err: &mut DiagnosticBuilder<'tcx>,
|
|
type_param_span: Option<(Span, bool, bool)>,
|
|
bound_kind: GenericKind<'tcx>,
|
|
sub: S,
|
|
) {
|
|
let consider = format!(
|
|
"consider adding an explicit lifetime bound {}",
|
|
if type_param_span.map(|(_, _, is_impl_trait)| is_impl_trait).unwrap_or(false) {
|
|
format!(" `{}` to `{}`...", sub, bound_kind)
|
|
} else {
|
|
format!("`{}: {}`...", bound_kind, sub)
|
|
},
|
|
);
|
|
if let Some((sp, has_lifetimes, is_impl_trait)) = type_param_span {
|
|
let suggestion = if is_impl_trait {
|
|
format!("{} + {}", bound_kind, sub)
|
|
} else {
|
|
let tail = if has_lifetimes { " + " } else { "" };
|
|
format!("{}: {}{}", bound_kind, sub, tail)
|
|
};
|
|
err.span_suggestion_short(
|
|
sp,
|
|
&consider,
|
|
suggestion,
|
|
Applicability::MaybeIncorrect, // Issue #41966
|
|
);
|
|
} else {
|
|
err.help(&consider);
|
|
}
|
|
}
|
|
|
|
let mut err = match *sub {
|
|
ty::ReEarlyBound(_)
|
|
| ty::ReFree(ty::FreeRegion {
|
|
bound_region: ty::BrNamed(..),
|
|
..
|
|
}) => {
|
|
// Does the required lifetime have a nice name we can print?
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0309,
|
|
"{} may not live long enough",
|
|
labeled_user_string
|
|
);
|
|
binding_suggestion(&mut err, type_param_span, bound_kind, sub);
|
|
err
|
|
}
|
|
|
|
ty::ReStatic => {
|
|
// Does the required lifetime have a nice name we can print?
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0310,
|
|
"{} may not live long enough",
|
|
labeled_user_string
|
|
);
|
|
binding_suggestion(&mut err, type_param_span, bound_kind, "'static");
|
|
err
|
|
}
|
|
|
|
_ => {
|
|
// If not, be less specific.
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0311,
|
|
"{} may not live long enough",
|
|
labeled_user_string
|
|
);
|
|
err.help(&format!(
|
|
"consider adding an explicit lifetime bound for `{}`",
|
|
bound_kind
|
|
));
|
|
self.tcx.note_and_explain_region(
|
|
region_scope_tree,
|
|
&mut err,
|
|
&format!("{} must be valid for ", labeled_user_string),
|
|
sub,
|
|
"...",
|
|
);
|
|
err
|
|
}
|
|
};
|
|
|
|
if let Some(origin) = origin {
|
|
self.note_region_origin(&mut err, &origin);
|
|
}
|
|
err
|
|
}
|
|
|
|
fn report_sub_sup_conflict(
|
|
&self,
|
|
region_scope_tree: ®ion::ScopeTree,
|
|
var_origin: RegionVariableOrigin,
|
|
sub_origin: SubregionOrigin<'tcx>,
|
|
sub_region: Region<'tcx>,
|
|
sup_origin: SubregionOrigin<'tcx>,
|
|
sup_region: Region<'tcx>,
|
|
) {
|
|
let mut err = self.report_inference_failure(var_origin);
|
|
|
|
self.tcx.note_and_explain_region(
|
|
region_scope_tree,
|
|
&mut err,
|
|
"first, the lifetime cannot outlive ",
|
|
sup_region,
|
|
"...",
|
|
);
|
|
|
|
match (&sup_origin, &sub_origin) {
|
|
(&infer::Subtype(ref sup_trace), &infer::Subtype(ref sub_trace)) => {
|
|
debug!("report_sub_sup_conflict: var_origin={:?}", var_origin);
|
|
debug!("report_sub_sup_conflict: sub_region={:?}", sub_region);
|
|
debug!("report_sub_sup_conflict: sub_origin={:?}", sub_origin);
|
|
debug!("report_sub_sup_conflict: sup_region={:?}", sup_region);
|
|
debug!("report_sub_sup_conflict: sup_origin={:?}", sup_origin);
|
|
debug!("report_sub_sup_conflict: sup_trace={:?}", sup_trace);
|
|
debug!("report_sub_sup_conflict: sub_trace={:?}", sub_trace);
|
|
debug!("report_sub_sup_conflict: sup_trace.values={:?}", sup_trace.values);
|
|
debug!("report_sub_sup_conflict: sub_trace.values={:?}", sub_trace.values);
|
|
|
|
if let (Some((sup_expected, sup_found)), Some((sub_expected, sub_found))) = (
|
|
self.values_str(&sup_trace.values),
|
|
self.values_str(&sub_trace.values),
|
|
) {
|
|
if sub_expected == sup_expected && sub_found == sup_found {
|
|
self.tcx.note_and_explain_region(
|
|
region_scope_tree,
|
|
&mut err,
|
|
"...but the lifetime must also be valid for ",
|
|
sub_region,
|
|
"...",
|
|
);
|
|
err.note(&format!(
|
|
"...so that the {}:\nexpected {}\n found {}",
|
|
sup_trace.cause.as_requirement_str(),
|
|
sup_expected.content(),
|
|
sup_found.content()
|
|
));
|
|
err.emit();
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
self.note_region_origin(&mut err, &sup_origin);
|
|
|
|
self.tcx.note_and_explain_region(
|
|
region_scope_tree,
|
|
&mut err,
|
|
"but, the lifetime must be valid for ",
|
|
sub_region,
|
|
"...",
|
|
);
|
|
|
|
self.note_region_origin(&mut err, &sub_origin);
|
|
err.emit();
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
|
|
fn report_inference_failure(
|
|
&self,
|
|
var_origin: RegionVariableOrigin,
|
|
) -> DiagnosticBuilder<'tcx> {
|
|
let br_string = |br: ty::BoundRegion| {
|
|
let mut s = match br {
|
|
ty::BrNamed(_, name) => name.to_string(),
|
|
_ => String::new(),
|
|
};
|
|
if !s.is_empty() {
|
|
s.push_str(" ");
|
|
}
|
|
s
|
|
};
|
|
let var_description = match var_origin {
|
|
infer::MiscVariable(_) => String::new(),
|
|
infer::PatternRegion(_) => " for pattern".to_string(),
|
|
infer::AddrOfRegion(_) => " for borrow expression".to_string(),
|
|
infer::Autoref(_) => " for autoref".to_string(),
|
|
infer::Coercion(_) => " for automatic coercion".to_string(),
|
|
infer::LateBoundRegion(_, br, infer::FnCall) => {
|
|
format!(" for lifetime parameter {}in function call", br_string(br))
|
|
}
|
|
infer::LateBoundRegion(_, br, infer::HigherRankedType) => {
|
|
format!(" for lifetime parameter {}in generic type", br_string(br))
|
|
}
|
|
infer::LateBoundRegion(_, br, infer::AssocTypeProjection(def_id)) => format!(
|
|
" for lifetime parameter {}in trait containing associated type `{}`",
|
|
br_string(br),
|
|
self.tcx.associated_item(def_id).ident
|
|
),
|
|
infer::EarlyBoundRegion(_, name) => format!(" for lifetime parameter `{}`", name),
|
|
infer::BoundRegionInCoherence(name) => {
|
|
format!(" for lifetime parameter `{}` in coherence check", name)
|
|
}
|
|
infer::UpvarRegion(ref upvar_id, _) => {
|
|
let var_name = self.tcx.hir().name_by_hir_id(upvar_id.var_path.hir_id);
|
|
format!(" for capture of `{}` by closure", var_name)
|
|
}
|
|
infer::NLL(..) => bug!("NLL variable found in lexical phase"),
|
|
};
|
|
|
|
struct_span_err!(
|
|
self.tcx.sess,
|
|
var_origin.span(),
|
|
E0495,
|
|
"cannot infer an appropriate lifetime{} \
|
|
due to conflicting requirements",
|
|
var_description
|
|
)
|
|
}
|
|
}
|
|
|
|
enum FailureCode {
|
|
Error0317(&'static str),
|
|
Error0580(&'static str),
|
|
Error0308(&'static str),
|
|
Error0644(&'static str),
|
|
}
|
|
|
|
impl<'tcx> ObligationCause<'tcx> {
|
|
fn as_failure_code(&self, terr: &TypeError<'tcx>) -> FailureCode {
|
|
use self::FailureCode::*;
|
|
use crate::traits::ObligationCauseCode::*;
|
|
match self.code {
|
|
CompareImplMethodObligation { .. } => Error0308("method not compatible with trait"),
|
|
MatchExpressionArm { source, .. } => Error0308(match source {
|
|
hir::MatchSource::IfLetDesugar { .. } => "`if let` arms have incompatible types",
|
|
hir::MatchSource::TryDesugar => {
|
|
"try expression alternatives have incompatible types"
|
|
}
|
|
_ => "match arms have incompatible types",
|
|
}),
|
|
IfExpression { .. } => Error0308("if and else have incompatible types"),
|
|
IfExpressionWithNoElse => Error0317("if may be missing an else clause"),
|
|
MainFunctionType => Error0580("main function has wrong type"),
|
|
StartFunctionType => Error0308("start function has wrong type"),
|
|
IntrinsicType => Error0308("intrinsic has wrong type"),
|
|
MethodReceiver => Error0308("mismatched method receiver"),
|
|
|
|
// In the case where we have no more specific thing to
|
|
// say, also take a look at the error code, maybe we can
|
|
// tailor to that.
|
|
_ => match terr {
|
|
TypeError::CyclicTy(ty) if ty.is_closure() || ty.is_generator() => {
|
|
Error0644("closure/generator type that references itself")
|
|
}
|
|
_ => Error0308("mismatched types"),
|
|
},
|
|
}
|
|
}
|
|
|
|
fn as_requirement_str(&self) -> &'static str {
|
|
use crate::traits::ObligationCauseCode::*;
|
|
match self.code {
|
|
CompareImplMethodObligation { .. } => "method type is compatible with trait",
|
|
ExprAssignable => "expression is assignable",
|
|
MatchExpressionArm { source, .. } => match source {
|
|
hir::MatchSource::IfLetDesugar { .. } => "`if let` arms have compatible types",
|
|
_ => "match arms have compatible types",
|
|
},
|
|
IfExpression { .. } => "if and else have compatible types",
|
|
IfExpressionWithNoElse => "if missing an else returns ()",
|
|
MainFunctionType => "`main` function has the correct type",
|
|
StartFunctionType => "`start` function has the correct type",
|
|
IntrinsicType => "intrinsic has the correct type",
|
|
MethodReceiver => "method receiver has the correct type",
|
|
_ => "types are compatible",
|
|
}
|
|
}
|
|
}
|