diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src')
10 files changed, 254 insertions, 108 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/alias_relate.rs b/compiler/rustc_trait_selection/src/solve/alias_relate.rs index 4d7e2fc2cef..59a8de99b8f 100644 --- a/compiler/rustc_trait_selection/src/solve/alias_relate.rs +++ b/compiler/rustc_trait_selection/src/solve/alias_relate.rs @@ -48,6 +48,12 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> { rhs }; + // Add a `make_canonical_response` probe step so that we treat this as + // a candidate, even if `try_evaluate_added_goals` bails due to an error. + // It's `Certainty::AMBIGUOUS` because this candidate is not "finished", + // since equating the normalized terms will lead to additional constraints. + self.inspect.make_canonical_response(Certainty::AMBIGUOUS); + // Apply the constraints. self.try_evaluate_added_goals()?; let lhs = self.resolve_vars_if_possible(lhs); diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs index dc13941e5d7..3c3d5dfe79c 100644 --- a/compiler/rustc_trait_selection/src/solve/fulfill.rs +++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs @@ -460,9 +460,10 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> { polarity: ty::PredicatePolarity::Positive, })) } - ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_)) => { - ChildMode::WellFormedObligation - } + ty::PredicateKind::Clause( + ty::ClauseKind::WellFormed(_) | ty::ClauseKind::Projection(..), + ) + | ty::PredicateKind::AliasRelate(..) => ChildMode::PassThrough, _ => { return ControlFlow::Break(self.obligation.clone()); } @@ -496,7 +497,7 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> { (_, GoalSource::InstantiateHigherRanked) => { obligation = self.obligation.clone(); } - (ChildMode::WellFormedObligation, _) => { + (ChildMode::PassThrough, _) => { obligation = make_obligation(self.obligation.cause.clone()); } } @@ -527,7 +528,7 @@ enum ChildMode<'tcx> { // Skip trying to derive an `ObligationCause` from this obligation, and // report *all* sub-obligations as if they came directly from the parent // obligation. - WellFormedObligation, + PassThrough, } fn derive_cause<'tcx>( diff --git a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs index 19c95dad48c..b9c98b6a2e9 100644 --- a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs +++ b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs @@ -15,7 +15,7 @@ use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk}; use rustc_macros::extension; use rustc_middle::traits::query::NoSolution; use rustc_middle::traits::solve::{inspect, QueryResult}; -use rustc_middle::traits::solve::{Certainty, Goal}; +use rustc_middle::traits::solve::{Certainty, Goal, MaybeCause}; use rustc_middle::traits::ObligationCause; use rustc_middle::ty::{TyCtxt, TypeFoldable}; use rustc_middle::{bug, ty}; @@ -291,7 +291,10 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> { steps.push(step) } inspect::ProbeStep::MakeCanonicalResponse { shallow_certainty: c } => { - assert_eq!(shallow_certainty.replace(c), None); + assert!(matches!( + shallow_certainty.replace(c), + None | Some(Certainty::Maybe(MaybeCause::Ambiguity)) + )); } inspect::ProbeStep::NestedProbe(ref probe) => { match probe.kind { diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index 087f7fbea00..4604c132835 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -3597,7 +3597,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { &self, obligation: &PredicateObligation<'tcx>, err: &mut Diag<'_>, - trait_ref: &ty::PolyTraitRef<'tcx>, + trait_ref: ty::PolyTraitRef<'tcx>, ) { let rhs_span = match obligation.cause.code() { ObligationCauseCode::BinOp { rhs_span: Some(span), rhs_is_lit, .. } if *rhs_is_lit => { @@ -4592,7 +4592,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { &self, obligation: &PredicateObligation<'tcx>, err: &mut Diag<'_>, - trait_ref: ty::PolyTraitRef<'tcx>, + trait_pred: ty::PolyTraitPredicate<'tcx>, ) { if ObligationCauseCode::QuestionMark != *obligation.cause.code().peel_derives() { return; @@ -4602,10 +4602,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { if let hir::Node::Item(item) = node && let hir::ItemKind::Fn(sig, _, body_id) = item.kind && let hir::FnRetTy::DefaultReturn(ret_span) = sig.decl.output - && self.tcx.is_diagnostic_item(sym::FromResidual, trait_ref.def_id()) - && let ty::Tuple(l) = trait_ref.skip_binder().args.type_at(0).kind() - && l.len() == 0 - && let ty::Adt(def, _) = trait_ref.skip_binder().args.type_at(1).kind() + && self.tcx.is_diagnostic_item(sym::FromResidual, trait_pred.def_id()) + && trait_pred.skip_binder().trait_ref.args.type_at(0).is_unit() + && let ty::Adt(def, _) = trait_pred.skip_binder().trait_ref.args.type_at(1).kind() && self.tcx.is_diagnostic_item(sym::Result, def.did()) { let body = self.tcx.hir().body(body_id); @@ -4863,14 +4862,13 @@ impl<'a, 'hir> hir::intravisit::Visitor<'hir> for ReplaceImplTraitVisitor<'a> { pub(super) fn get_explanation_based_on_obligation<'tcx>( tcx: TyCtxt<'tcx>, obligation: &PredicateObligation<'tcx>, - trait_ref: ty::PolyTraitRef<'tcx>, - trait_predicate: &ty::PolyTraitPredicate<'tcx>, + trait_predicate: ty::PolyTraitPredicate<'tcx>, pre_message: String, ) -> String { if let ObligationCauseCode::MainFunctionType = obligation.cause.code() { "consider using `()`, or a `Result`".to_owned() } else { - let ty_desc = match trait_ref.skip_binder().self_ty().kind() { + let ty_desc = match trait_predicate.self_ty().skip_binder().kind() { ty::FnDef(_, _) => Some("fn item"), ty::Closure(_, _) => Some("closure"), _ => None, @@ -4895,7 +4893,7 @@ pub(super) fn get_explanation_based_on_obligation<'tcx>( format!( "{pre_message}the trait `{}` is not implemented for{desc} `{}`{post}", trait_predicate.print_modifiers_and_trait_path(), - tcx.short_ty_string(trait_ref.skip_binder().self_ty(), &mut None), + tcx.short_ty_string(trait_predicate.self_ty().skip_binder(), &mut None), ) } else { // "the trait bound `T: !Send` is not satisfied" reads better than "`!Send` is diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs index 6b6438a7887..aef9d482bec 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs @@ -412,8 +412,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { let bound_predicate = obligation.predicate.kind(); match bound_predicate.skip_binder() { ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_predicate)) => { - let trait_predicate = bound_predicate.rebind(trait_predicate); - let trait_predicate = self.resolve_vars_if_possible(trait_predicate); + let leaf_trait_predicate = + self.resolve_vars_if_possible(bound_predicate.rebind(trait_predicate)); // Let's use the root obligation as the main message, when we care about the // most general case ("X doesn't implement Pattern<'_>") over the case that @@ -424,7 +424,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { let (main_trait_predicate, o) = if let ty::PredicateKind::Clause( ty::ClauseKind::Trait(root_pred) ) = root_obligation.predicate.kind().skip_binder() - && !trait_predicate.self_ty().skip_binder().has_escaping_bound_vars() + && !leaf_trait_predicate.self_ty().skip_binder().has_escaping_bound_vars() && !root_pred.self_ty().has_escaping_bound_vars() // The type of the leaf predicate is (roughly) the same as the type // from the root predicate, as a proxy for "we care about the root" @@ -434,20 +434,20 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { // `T: Trait` && `&&T: OtherTrait`, we want `OtherTrait` self.can_eq( obligation.param_env, - trait_predicate.self_ty().skip_binder(), + leaf_trait_predicate.self_ty().skip_binder(), root_pred.self_ty().peel_refs(), ) // `&str: Iterator` && `&str: IntoIterator`, we want `IntoIterator` || self.can_eq( obligation.param_env, - trait_predicate.self_ty().skip_binder(), + leaf_trait_predicate.self_ty().skip_binder(), root_pred.self_ty(), ) ) // The leaf trait and the root trait are different, so as to avoid // talking about `&mut T: Trait` and instead remain talking about // `T: Trait` instead - && trait_predicate.def_id() != root_pred.def_id() + && leaf_trait_predicate.def_id() != root_pred.def_id() // The root trait is not `Unsize`, as to avoid talking about it in // `tests/ui/coercion/coerce-issue-49593-box-never.rs`. && Some(root_pred.def_id()) != self.tcx.lang_items().unsize_trait() @@ -459,13 +459,14 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { root_obligation, ) } else { - (trait_predicate, &obligation) + (leaf_trait_predicate, &obligation) }; - let trait_ref = main_trait_predicate.to_poly_trait_ref(); + let main_trait_ref = main_trait_predicate.to_poly_trait_ref(); + let leaf_trait_ref = leaf_trait_predicate.to_poly_trait_ref(); if let Some(guar) = self.emit_specialized_closure_kind_error( &obligation, - trait_ref, + leaf_trait_ref, ) { return guar; } @@ -473,7 +474,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { // FIXME(effects) let predicate_is_const = false; - if let Err(guar) = trait_predicate.error_reported() + if let Err(guar) = leaf_trait_predicate.error_reported() { return guar; } @@ -507,16 +508,17 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { notes, parent_label, append_const_msg, - } = self.on_unimplemented_note(trait_ref, o, &mut long_ty_file); + } = self.on_unimplemented_note(main_trait_ref, o, &mut long_ty_file); + let have_alt_message = message.is_some() || label.is_some(); - let is_try_conversion = self.is_try_conversion(span, trait_ref.def_id()); + let is_try_conversion = self.is_try_conversion(span, main_trait_ref.def_id()); let is_unsize = - Some(trait_ref.def_id()) == self.tcx.lang_items().unsize_trait(); + Some(leaf_trait_ref.def_id()) == self.tcx.lang_items().unsize_trait(); let (message, notes, append_const_msg) = if is_try_conversion { ( Some(format!( "`?` couldn't convert the error to `{}`", - trait_ref.skip_binder().self_ty(), + main_trait_ref.skip_binder().self_ty(), )), vec![ "the question mark operation (`?`) implicitly performs a \ @@ -530,20 +532,20 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { }; let err_msg = self.get_standard_error_message( - &main_trait_predicate, + main_trait_predicate, message, predicate_is_const, append_const_msg, post_message, ); - let (err_msg, safe_transmute_explanation) = if Some(trait_ref.def_id()) + let (err_msg, safe_transmute_explanation) = if Some(main_trait_ref.def_id()) == self.tcx.lang_items().transmute_trait() { // Recompute the safe transmute reason and use that for the error reporting match self.get_safe_transmute_error_and_reason( obligation.clone(), - trait_ref, + main_trait_ref, span, ) { GetSafeTransmuteErrorAndReason::Silent => { @@ -571,7 +573,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { } let mut suggested = false; if is_try_conversion { - suggested = self.try_conversion_context(&obligation, trait_ref.skip_binder(), &mut err); + suggested = self.try_conversion_context(&obligation, main_trait_ref.skip_binder(), &mut err); } if is_try_conversion && let Some(ret_span) = self.return_type_span(&obligation) { @@ -579,19 +581,19 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { ret_span, format!( "expected `{}` because of this", - trait_ref.skip_binder().self_ty() + main_trait_ref.skip_binder().self_ty() ), ); } - if Some(trait_ref.def_id()) == tcx.lang_items().tuple_trait() { + if Some(leaf_trait_ref.def_id()) == tcx.lang_items().tuple_trait() { self.add_tuple_trait_message( obligation.cause.code().peel_derives(), &mut err, ); } - if Some(trait_ref.def_id()) == tcx.lang_items().drop_trait() + if Some(leaf_trait_ref.def_id()) == tcx.lang_items().drop_trait() && predicate_is_const { err.note("`~const Drop` was renamed to `~const Destruct`"); @@ -601,24 +603,25 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { let explanation = get_explanation_based_on_obligation( self.tcx, &obligation, - trait_ref, - &trait_predicate, + leaf_trait_predicate, pre_message, ); self.check_for_binding_assigned_block_without_tail_expression( &obligation, &mut err, - trait_predicate, + leaf_trait_predicate, ); - self.suggest_add_result_as_return_type(&obligation, + self.suggest_add_result_as_return_type( + &obligation, &mut err, - trait_ref); + leaf_trait_predicate, + ); if self.suggest_add_reference_to_arg( &obligation, &mut err, - trait_predicate, + leaf_trait_predicate, have_alt_message, ) { self.note_obligation_cause(&mut err, &obligation); @@ -630,7 +633,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { // If it has a custom `#[rustc_on_unimplemented]` // error message, let's display it as the label! err.span_label(span, s); - if !matches!(trait_ref.skip_binder().self_ty().kind(), ty::Param(_)) { + if !matches!(leaf_trait_ref.skip_binder().self_ty().kind(), ty::Param(_)) { // When the self type is a type param We don't need to "the trait // `std::marker::Sized` is not implemented for `T`" as we will point // at the type param with a label to suggest constraining it. @@ -645,7 +648,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { if let ObligationCauseCode::Coercion { source, target } = *obligation.cause.code().peel_derives() { - if Some(trait_ref.def_id()) == self.tcx.lang_items().sized_trait() { + if Some(leaf_trait_ref.def_id()) == self.tcx.lang_items().sized_trait() { self.suggest_borrowing_for_object_cast( &mut err, root_obligation, @@ -657,7 +660,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { let UnsatisfiedConst(unsatisfied_const) = self .maybe_add_note_for_unsatisfied_const( - &trait_predicate, + leaf_trait_predicate, &mut err, span, ); @@ -674,15 +677,15 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { err.span_label(tcx.def_span(body), s); } - self.suggest_floating_point_literal(&obligation, &mut err, &trait_ref); - self.suggest_dereferencing_index(&obligation, &mut err, trait_predicate); - suggested |= self.suggest_dereferences(&obligation, &mut err, trait_predicate); - suggested |= self.suggest_fn_call(&obligation, &mut err, trait_predicate); - let impl_candidates = self.find_similar_impl_candidates(trait_predicate); + self.suggest_floating_point_literal(&obligation, &mut err, leaf_trait_ref); + self.suggest_dereferencing_index(&obligation, &mut err, leaf_trait_predicate); + suggested |= self.suggest_dereferences(&obligation, &mut err, leaf_trait_predicate); + suggested |= self.suggest_fn_call(&obligation, &mut err, leaf_trait_predicate); + let impl_candidates = self.find_similar_impl_candidates(leaf_trait_predicate); suggested = if let &[cand] = &impl_candidates[..] { let cand = cand.trait_ref; if let (ty::FnPtr(_), ty::FnDef(..)) = - (cand.self_ty().kind(), trait_ref.self_ty().skip_binder().kind()) + (cand.self_ty().kind(), main_trait_ref.self_ty().skip_binder().kind()) { err.span_suggestion( span.shrink_to_hi(), @@ -702,31 +705,31 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { false } || suggested; suggested |= - self.suggest_remove_reference(&obligation, &mut err, trait_predicate); + self.suggest_remove_reference(&obligation, &mut err, leaf_trait_predicate); suggested |= self.suggest_semicolon_removal( &obligation, &mut err, span, - trait_predicate, + leaf_trait_predicate, ); - self.note_version_mismatch(&mut err, &trait_ref); + self.note_version_mismatch(&mut err, leaf_trait_ref); self.suggest_remove_await(&obligation, &mut err); - self.suggest_derive(&obligation, &mut err, trait_predicate); + self.suggest_derive(&obligation, &mut err, leaf_trait_predicate); - if Some(trait_ref.def_id()) == tcx.lang_items().try_trait() { + if Some(leaf_trait_ref.def_id()) == tcx.lang_items().try_trait() { self.suggest_await_before_try( &mut err, &obligation, - trait_predicate, + leaf_trait_predicate, span, ); } - if self.suggest_add_clone_to_arg(&obligation, &mut err, trait_predicate) { + if self.suggest_add_clone_to_arg(&obligation, &mut err, leaf_trait_predicate) { return err.emit(); } - if self.suggest_impl_trait(&mut err, &obligation, trait_predicate) { + if self.suggest_impl_trait(&mut err, &obligation, leaf_trait_predicate) { return err.emit(); } @@ -741,9 +744,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { ); } - let is_fn_trait = tcx.is_fn_trait(trait_ref.def_id()); + let is_fn_trait = tcx.is_fn_trait(leaf_trait_ref.def_id()); let is_target_feature_fn = if let ty::FnDef(def_id, _) = - *trait_ref.skip_binder().self_ty().kind() + *leaf_trait_ref.skip_binder().self_ty().kind() { !self.tcx.codegen_fn_attrs(def_id).target_features.is_empty() } else { @@ -757,8 +760,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { self.try_to_add_help_message( &obligation, - trait_ref, - &trait_predicate, + leaf_trait_predicate, &mut err, span, is_fn_trait, @@ -769,17 +771,17 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { // Changing mutability doesn't make a difference to whether we have // an `Unsize` impl (Fixes ICE in #71036) if !is_unsize { - self.suggest_change_mut(&obligation, &mut err, trait_predicate); + self.suggest_change_mut(&obligation, &mut err, leaf_trait_predicate); } // If this error is due to `!: Trait` not implemented but `(): Trait` is // implemented, and fallback has occurred, then it could be due to a // variable that used to fallback to `()` now falling back to `!`. Issue a // note informing about the change in behaviour. - if trait_predicate.skip_binder().self_ty().is_never() + if leaf_trait_predicate.skip_binder().self_ty().is_never() && self.fallback_has_occurred { - let predicate = trait_predicate.map_bound(|trait_pred| { + let predicate = leaf_trait_predicate.map_bound(|trait_pred| { trait_pred.with_self_ty(self.tcx, tcx.types.unit) }); let unit_obligation = obligation.with(tcx, predicate); @@ -794,8 +796,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { } } - self.explain_hrtb_projection(&mut err, trait_predicate, obligation.param_env, &obligation.cause); - self.suggest_desugaring_async_fn_in_trait(&mut err, trait_ref); + self.explain_hrtb_projection(&mut err, leaf_trait_predicate, obligation.param_env, &obligation.cause); + self.suggest_desugaring_async_fn_in_trait(&mut err, main_trait_ref); // Return early if the trait is Debug or Display and the invocation // originates within a standard library macro, because the output @@ -813,15 +815,13 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { if in_std_macro && matches!( - self.tcx.get_diagnostic_name(trait_ref.def_id()), + self.tcx.get_diagnostic_name(leaf_trait_ref.def_id()), Some(sym::Debug | sym::Display) ) { return err.emit(); } - - err } @@ -2236,11 +2236,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { /// If the `Self` type of the unsatisfied trait `trait_ref` implements a trait /// with the same path as `trait_ref`, a help message about /// a probable version mismatch is added to `err` - fn note_version_mismatch( - &self, - err: &mut Diag<'_>, - trait_ref: &ty::PolyTraitRef<'tcx>, - ) -> bool { + fn note_version_mismatch(&self, err: &mut Diag<'_>, trait_ref: ty::PolyTraitRef<'tcx>) -> bool { let get_trait_impls = |trait_def_id| { let mut trait_impls = vec![]; self.tcx.for_each_relevant_impl( @@ -2705,6 +2701,22 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { ), ); } + + ty::PredicateKind::NormalizesTo(ty::NormalizesTo { alias, term }) + if term.is_infer() => + { + if let Some(e) = self.tainted_by_errors() { + return e; + } + struct_span_code_err!( + self.dcx(), + span, + E0284, + "type annotations needed: cannot normalize `{alias}`", + ) + .with_span_label(span, format!("cannot normalize `{alias}`")) + } + _ => { if let Some(e) = self.tainted_by_errors() { return e; @@ -3044,7 +3056,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { fn get_standard_error_message( &self, - trait_predicate: &ty::PolyTraitPredicate<'tcx>, + trait_predicate: ty::PolyTraitPredicate<'tcx>, message: Option<String>, predicate_is_const: bool, append_const_msg: Option<AppendConstMessage>, @@ -3215,8 +3227,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { fn try_to_add_help_message( &self, obligation: &PredicateObligation<'tcx>, - trait_ref: ty::PolyTraitRef<'tcx>, - trait_predicate: &ty::PolyTraitPredicate<'tcx>, + trait_predicate: ty::PolyTraitPredicate<'tcx>, err: &mut Diag<'_>, span: Span, is_fn_trait: bool, @@ -3233,16 +3244,22 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { }; // Try to report a help message + let trait_def_id = trait_predicate.def_id(); if is_fn_trait && let Ok((implemented_kind, params)) = self.type_implements_fn_trait( obligation.param_env, - trait_ref.self_ty(), + trait_predicate.self_ty(), trait_predicate.skip_binder().polarity, ) { - self.add_help_message_for_fn_trait(trait_ref, err, implemented_kind, params); - } else if !trait_ref.has_non_region_infer() - && self.predicate_can_apply(obligation.param_env, *trait_predicate) + self.add_help_message_for_fn_trait( + trait_predicate.to_poly_trait_ref(), + err, + implemented_kind, + params, + ); + } else if !trait_predicate.has_non_region_infer() + && self.predicate_can_apply(obligation.param_env, trait_predicate) { // If a where-clause may be useful, remind the // user that they can add it. @@ -3253,25 +3270,25 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { // which is somewhat confusing. self.suggest_restricting_param_bound( err, - *trait_predicate, + trait_predicate, None, obligation.cause.body_id, ); - } else if trait_ref.def_id().is_local() - && self.tcx.trait_impls_of(trait_ref.def_id()).is_empty() - && !self.tcx.trait_is_auto(trait_ref.def_id()) - && !self.tcx.trait_is_alias(trait_ref.def_id()) + } else if trait_def_id.is_local() + && self.tcx.trait_impls_of(trait_def_id).is_empty() + && !self.tcx.trait_is_auto(trait_def_id) + && !self.tcx.trait_is_alias(trait_def_id) { err.span_help( - self.tcx.def_span(trait_ref.def_id()), + self.tcx.def_span(trait_def_id), crate::fluent_generated::trait_selection_trait_has_no_impls, ); } else if !suggested && !unsatisfied_const { // Can't show anything else useful, try to find similar impls. - let impl_candidates = self.find_similar_impl_candidates(*trait_predicate); + let impl_candidates = self.find_similar_impl_candidates(trait_predicate); if !self.report_similar_impl_candidates( &impl_candidates, - trait_ref, + trait_predicate.to_poly_trait_ref(), body_def_id, err, true, @@ -3279,7 +3296,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { ) { self.report_similar_impl_candidates_for_root_obligation( obligation, - *trait_predicate, + trait_predicate, body_def_id, err, ); @@ -3288,7 +3305,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { self.suggest_convert_to_slice( err, obligation, - trait_ref, + trait_predicate.to_poly_trait_ref(), impl_candidates.as_slice(), span, ); @@ -3353,7 +3370,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { fn maybe_add_note_for_unsatisfied_const( &self, - _trait_predicate: &ty::PolyTraitPredicate<'tcx>, + _trait_predicate: ty::PolyTraitPredicate<'tcx>, _err: &mut Diag<'_>, _span: Span, ) -> UnsatisfiedConst { diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs index 08355ef55c4..fc5a2875b67 100644 --- a/compiler/rustc_trait_selection/src/traits/object_safety.rs +++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs @@ -194,7 +194,7 @@ fn predicates_reference_self( predicates .predicates .iter() - .map(|&(predicate, sp)| (predicate.instantiate_supertrait(tcx, &trait_ref), sp)) + .map(|&(predicate, sp)| (predicate.instantiate_supertrait(tcx, trait_ref), sp)) .filter_map(|predicate| predicate_references_self(tcx, predicate)) .collect() } diff --git a/compiler/rustc_trait_selection/src/traits/select/_match.rs b/compiler/rustc_trait_selection/src/traits/select/_match.rs new file mode 100644 index 00000000000..50d8e96aaf9 --- /dev/null +++ b/compiler/rustc_trait_selection/src/traits/select/_match.rs @@ -0,0 +1,121 @@ +use rustc_infer::infer::relate::{ + self, structurally_relate_tys, Relate, RelateResult, TypeRelation, +}; +use rustc_middle::ty::error::{ExpectedFound, TypeError}; +use rustc_middle::ty::{self, InferConst, Ty, TyCtxt}; +use tracing::{debug, instrument}; + +/// A type "A" *matches* "B" if the fresh types in B could be +/// instantiated with values so as to make it equal to A. Matching is +/// intended to be used only on freshened types, and it basically +/// indicates if the non-freshened versions of A and B could have been +/// unified. +/// +/// It is only an approximation. If it yields false, unification would +/// definitely fail, but a true result doesn't mean unification would +/// succeed. This is because we don't track the "side-constraints" on +/// type variables, nor do we track if the same freshened type appears +/// more than once. To some extent these approximations could be +/// fixed, given effort. +/// +/// Like subtyping, matching is really a binary relation, so the only +/// important thing about the result is Ok/Err. Also, matching never +/// affects any type variables or unification state. +pub struct MatchAgainstFreshVars<'tcx> { + tcx: TyCtxt<'tcx>, +} + +impl<'tcx> MatchAgainstFreshVars<'tcx> { + pub fn new(tcx: TyCtxt<'tcx>) -> MatchAgainstFreshVars<'tcx> { + MatchAgainstFreshVars { tcx } + } +} + +impl<'tcx> TypeRelation<TyCtxt<'tcx>> for MatchAgainstFreshVars<'tcx> { + fn tag(&self) -> &'static str { + "MatchAgainstFreshVars" + } + + fn tcx(&self) -> TyCtxt<'tcx> { + self.tcx + } + + fn relate_with_variance<T: Relate<TyCtxt<'tcx>>>( + &mut self, + _: ty::Variance, + _: ty::VarianceDiagInfo<TyCtxt<'tcx>>, + a: T, + b: T, + ) -> RelateResult<'tcx, T> { + self.relate(a, b) + } + + #[instrument(skip(self), level = "debug")] + fn regions( + &mut self, + a: ty::Region<'tcx>, + _b: ty::Region<'tcx>, + ) -> RelateResult<'tcx, ty::Region<'tcx>> { + Ok(a) + } + + #[instrument(skip(self), level = "debug")] + fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> { + if a == b { + return Ok(a); + } + + match (a.kind(), b.kind()) { + ( + _, + &ty::Infer(ty::FreshTy(_)) + | &ty::Infer(ty::FreshIntTy(_)) + | &ty::Infer(ty::FreshFloatTy(_)), + ) => Ok(a), + + (&ty::Infer(_), _) | (_, &ty::Infer(_)) => { + Err(TypeError::Sorts(ExpectedFound::new(true, a, b))) + } + + (&ty::Error(guar), _) | (_, &ty::Error(guar)) => Ok(Ty::new_error(self.tcx(), guar)), + + _ => structurally_relate_tys(self, a, b), + } + } + + fn consts( + &mut self, + a: ty::Const<'tcx>, + b: ty::Const<'tcx>, + ) -> RelateResult<'tcx, ty::Const<'tcx>> { + debug!("{}.consts({:?}, {:?})", self.tag(), a, b); + if a == b { + return Ok(a); + } + + match (a.kind(), b.kind()) { + (_, ty::ConstKind::Infer(InferConst::Fresh(_))) => { + return Ok(a); + } + + (ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => { + return Err(TypeError::ConstMismatch(ExpectedFound::new(true, a, b))); + } + + _ => {} + } + + relate::structurally_relate_consts(self, a, b) + } + + fn binders<T>( + &mut self, + a: ty::Binder<'tcx, T>, + b: ty::Binder<'tcx, T>, + ) -> RelateResult<'tcx, ty::Binder<'tcx, T>> + where + T: Relate<TyCtxt<'tcx>>, + { + Ok(a.rebind(self.relate(a.skip_binder(), b.skip_binder())?)) + } +} diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index 4306a803524..212ef2e4b2b 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -32,7 +32,6 @@ use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_errors::{Diag, EmissionGuarantee}; use rustc_hir as hir; use rustc_hir::def_id::DefId; -use rustc_infer::infer::relate::MatchAgainstFreshVars; use rustc_infer::infer::relate::TypeRelation; use rustc_infer::infer::BoundRegionConversionTime; use rustc_infer::infer::BoundRegionConversionTime::HigherRankedType; @@ -60,6 +59,7 @@ use std::ops::ControlFlow; pub use rustc_middle::traits::select::*; use rustc_middle::ty::print::with_no_trimmed_paths; +mod _match; mod candidate_assembly; mod confirmation; @@ -1866,7 +1866,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> { // the param_env so that it can be given the lowest priority. See // #50825 for the motivation for this. let is_global = - |cand: &ty::PolyTraitPredicate<'tcx>| cand.is_global() && !cand.has_bound_vars(); + |cand: ty::PolyTraitPredicate<'tcx>| cand.is_global() && !cand.has_bound_vars(); // (*) Prefer `BuiltinCandidate { has_nested: false }`, `PointeeCandidate`, // `DiscriminantKindCandidate`, `ConstDestructCandidate` @@ -1909,7 +1909,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> { } ( - ParamCandidate(ref other_cand), + ParamCandidate(other_cand), ImplCandidate(..) | AutoImplCandidate | ClosureCandidate { .. } @@ -1934,12 +1934,12 @@ impl<'tcx> SelectionContext<'_, 'tcx> { // // Global bounds from the where clause should be ignored // here (see issue #50825). - DropVictim::drop_if(!is_global(other_cand)) + DropVictim::drop_if(!is_global(*other_cand)) } - (ObjectCandidate(_) | ProjectionCandidate(_), ParamCandidate(ref victim_cand)) => { + (ObjectCandidate(_) | ProjectionCandidate(_), ParamCandidate(victim_cand)) => { // Prefer these to a global where-clause bound // (see issue #50825). - if is_global(victim_cand) { DropVictim::Yes } else { DropVictim::No } + if is_global(*victim_cand) { DropVictim::Yes } else { DropVictim::No } } ( ImplCandidate(_) @@ -1957,12 +1957,12 @@ impl<'tcx> SelectionContext<'_, 'tcx> { | TraitUpcastingUnsizeCandidate(_) | BuiltinCandidate { has_nested: true } | TraitAliasCandidate, - ParamCandidate(ref victim_cand), + ParamCandidate(victim_cand), ) => { // Prefer these to a global where-clause bound // (see issue #50825). DropVictim::drop_if( - is_global(victim_cand) && other.evaluation.must_apply_modulo_regions(), + is_global(*victim_cand) && other.evaluation.must_apply_modulo_regions(), ) } @@ -2719,7 +2719,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> { previous: ty::PolyTraitPredicate<'tcx>, current: ty::PolyTraitPredicate<'tcx>, ) -> bool { - let mut matcher = MatchAgainstFreshVars::new(self.tcx()); + let mut matcher = _match::MatchAgainstFreshVars::new(self.tcx()); matcher.relate(previous, current).is_ok() } diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs index 960c27b636e..ce7245d93a4 100644 --- a/compiler/rustc_trait_selection/src/traits/util.rs +++ b/compiler/rustc_trait_selection/src/traits/util.rs @@ -132,7 +132,7 @@ impl<'tcx> TraitAliasExpander<'tcx> { debug!(?predicates); let items = predicates.predicates.iter().rev().filter_map(|(pred, span)| { - pred.instantiate_supertrait(tcx, &trait_ref) + pred.instantiate_supertrait(tcx, trait_ref) .as_trait_clause() .map(|trait_ref| item.clone_and_push(trait_ref.map_bound(|t| t.trait_ref), *span)) }); diff --git a/compiler/rustc_trait_selection/src/traits/vtable.rs b/compiler/rustc_trait_selection/src/traits/vtable.rs index c93ec43944a..9bd4a9aab0a 100644 --- a/compiler/rustc_trait_selection/src/traits/vtable.rs +++ b/compiler/rustc_trait_selection/src/traits/vtable.rs @@ -125,7 +125,7 @@ fn prepare_vtable_segments_inner<'tcx, T>( .predicates .into_iter() .filter_map(move |(pred, _)| { - pred.instantiate_supertrait(tcx, &inner_most_trait_ref).as_trait_clause() + pred.instantiate_supertrait(tcx, inner_most_trait_ref).as_trait_clause() }); // Find an unvisited supertrait |