diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/traits/project.rs')
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/project.rs | 142 |
1 files changed, 104 insertions, 38 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs index a25fb8543..e4284b9d3 100644 --- a/compiler/rustc_trait_selection/src/traits/project.rs +++ b/compiler/rustc_trait_selection/src/traits/project.rs @@ -18,7 +18,7 @@ use super::{Normalized, NormalizedTy, ProjectionCacheEntry, ProjectionCacheKey}; use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; use crate::infer::{InferCtxt, InferOk, LateBoundRegionConversionTime}; -use crate::traits::error_reporting::InferCtxtExt as _; +use crate::traits::error_reporting::TypeErrCtxtExt as _; use crate::traits::query::evaluate_obligation::InferCtxtExt as _; use crate::traits::select::ProjectionMatchesProjection; use rustc_data_structures::sso::SsoHashSet; @@ -30,7 +30,6 @@ use rustc_hir::lang_items::LangItem; use rustc_infer::infer::resolve::OpportunisticRegionResolver; use rustc_middle::traits::select::OverflowError; use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable}; -use rustc_middle::ty::subst::Subst; use rustc_middle::ty::visit::{MaxUniverse, TypeVisitable}; use rustc_middle::ty::DefIdTree; use rustc_middle::ty::{self, Term, ToPredicate, Ty, TyCtxt}; @@ -63,7 +62,8 @@ enum ProjectionCandidate<'tcx> { /// From a where-clause in the env or object type ParamEnv(ty::PolyProjectionPredicate<'tcx>), - /// From the definition of `Trait` when you have something like <<A as Trait>::B as Trait2>::C + /// From the definition of `Trait` when you have something like + /// `<<A as Trait>::B as Trait2>::C`. TraitDef(ty::PolyProjectionPredicate<'tcx>), /// Bounds specified on an object type @@ -72,7 +72,15 @@ enum ProjectionCandidate<'tcx> { /// From an "impl" (or a "pseudo-impl" returned by select) Select(Selection<'tcx>), - ImplTraitInTrait(ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>>), + ImplTraitInTrait(ImplTraitInTraitCandidate<'tcx>), +} + +#[derive(PartialEq, Eq, Debug)] +enum ImplTraitInTraitCandidate<'tcx> { + // The `impl Trait` from a trait function's default body + Trait, + // A concrete type provided from a trait's `impl Trait` from an impl + Impl(ImplSourceUserDefinedData<'tcx, PredicateObligation<'tcx>>), } enum ProjectionCandidateSet<'tcx> { @@ -256,7 +264,7 @@ fn project_and_unify_type<'cx, 'tcx>( }; debug!(?normalized, ?obligations, "project_and_unify_type result"); let actual = obligation.predicate.term; - // For an example where this is neccessary see src/test/ui/impl-trait/nested-return-type2.rs + // For an example where this is necessary see src/test/ui/impl-trait/nested-return-type2.rs // This allows users to omit re-mentioning all bounds on an associated type and just use an // `impl Trait` for the assoc type to add more bounds. let InferOk { value: actual, obligations: new } = @@ -514,7 +522,7 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> { self.param_env, ty, ); - self.selcx.infcx().report_overflow_error(&obligation, true); + self.selcx.infcx().err_ctxt().report_overflow_error(&obligation, true); } let substs = substs.fold_with(self); @@ -557,21 +565,6 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> { .flatten() .unwrap_or_else(|| ty.super_fold_with(self).into()) }; - // For cases like #95134 we would like to catch overflows early - // otherwise they slip away away and cause ICE. - let recursion_limit = self.tcx().recursion_limit(); - if !recursion_limit.value_within_limit(self.depth) - // HACK: Don't overflow when running cargo doc see #100991 - && !self.tcx().sess.opts.actually_rustdoc - { - let obligation = Obligation::with_depth( - self.cause.clone(), - recursion_limit.0, - self.param_env, - ty, - ); - self.selcx.infcx().report_overflow_error(&obligation, true); - } debug!( ?self.depth, ?ty, @@ -664,7 +657,7 @@ impl<'a, 'b, 'tcx> TypeFolder<'tcx> for AssocTypeNormalizer<'a, 'b, 'tcx> { } pub struct BoundVarReplacer<'me, 'tcx> { - infcx: &'me InferCtxt<'me, 'tcx>, + infcx: &'me InferCtxt<'tcx>, // These three maps track the bound variable that were replaced by placeholders. It might be // nice to remove these since we already have the `kind` in the placeholder; we really just need // the `var` (but we *could* bring that into scope if we were to track them as we pass them). @@ -692,7 +685,7 @@ pub struct BoundVarReplacer<'me, 'tcx> { /// FIXME(@lcnr): We may even consider experimenting with eagerly replacing bound vars during /// normalization as well, at which point this function will be unnecessary and can be removed. pub fn with_replaced_escaping_bound_vars<'a, 'tcx, T: TypeFoldable<'tcx>, R: TypeFoldable<'tcx>>( - infcx: &'a InferCtxt<'a, 'tcx>, + infcx: &'a InferCtxt<'tcx>, universe_indices: &'a mut Vec<Option<ty::UniverseIndex>>, value: T, f: impl FnOnce(T) -> R, @@ -718,7 +711,7 @@ impl<'me, 'tcx> BoundVarReplacer<'me, 'tcx> { /// Returns `Some` if we *were* able to replace bound vars. If there are any bound vars that /// use a binding level above `universe_indices.len()`, we fail. pub fn replace_bound_vars<T: TypeFoldable<'tcx>>( - infcx: &'me InferCtxt<'me, 'tcx>, + infcx: &'me InferCtxt<'tcx>, universe_indices: &'me mut Vec<Option<ty::UniverseIndex>>, value: T, ) -> ( @@ -838,7 +831,7 @@ impl<'tcx> TypeFolder<'tcx> for BoundVarReplacer<'_, 'tcx> { // The inverse of `BoundVarReplacer`: replaces placeholders with the bound vars from which they came. pub struct PlaceholderReplacer<'me, 'tcx> { - infcx: &'me InferCtxt<'me, 'tcx>, + infcx: &'me InferCtxt<'tcx>, mapped_regions: BTreeMap<ty::PlaceholderRegion, ty::BoundRegion>, mapped_types: BTreeMap<ty::PlaceholderType, ty::BoundTy>, mapped_consts: BTreeMap<ty::PlaceholderConst<'tcx>, ty::BoundVar>, @@ -848,7 +841,7 @@ pub struct PlaceholderReplacer<'me, 'tcx> { impl<'me, 'tcx> PlaceholderReplacer<'me, 'tcx> { pub fn replace_placeholders<T: TypeFoldable<'tcx>>( - infcx: &'me InferCtxt<'me, 'tcx>, + infcx: &'me InferCtxt<'tcx>, mapped_regions: BTreeMap<ty::PlaceholderRegion, ty::BoundRegion>, mapped_types: BTreeMap<ty::PlaceholderType, ty::BoundTy>, mapped_consts: BTreeMap<ty::PlaceholderConst<'tcx>, ty::BoundVar>, @@ -1319,6 +1312,19 @@ fn assemble_candidate_for_impl_trait_in_trait<'cx, 'tcx>( let tcx = selcx.tcx(); if tcx.def_kind(obligation.predicate.item_def_id) == DefKind::ImplTraitPlaceholder { let trait_fn_def_id = tcx.impl_trait_in_trait_parent(obligation.predicate.item_def_id); + // If we are trying to project an RPITIT with trait's default `Self` parameter, + // then we must be within a default trait body. + if obligation.predicate.self_ty() + == ty::InternalSubsts::identity_for_item(tcx, obligation.predicate.item_def_id) + .type_at(0) + && tcx.associated_item(trait_fn_def_id).defaultness(tcx).has_value() + { + candidate_set.push_candidate(ProjectionCandidate::ImplTraitInTrait( + ImplTraitInTraitCandidate::Trait, + )); + return; + } + let trait_def_id = tcx.parent(trait_fn_def_id); let trait_substs = obligation.predicate.substs.truncate_to(tcx, tcx.generics_of(trait_def_id)); @@ -1330,7 +1336,9 @@ fn assemble_candidate_for_impl_trait_in_trait<'cx, 'tcx>( let _ = selcx.infcx().commit_if_ok(|_| match selcx.select(&obligation.with(trait_predicate)) { Ok(Some(super::ImplSource::UserDefined(data))) => { - candidate_set.push_candidate(ProjectionCandidate::ImplTraitInTrait(data)); + candidate_set.push_candidate(ProjectionCandidate::ImplTraitInTrait( + ImplTraitInTraitCandidate::Impl(data), + )); Ok(()) } Ok(None) => { @@ -1368,7 +1376,7 @@ fn assemble_candidates_from_param_env<'cx, 'tcx>( ); } -/// In the case of a nested projection like <<A as Foo>::FooT as Bar>::BarT, we may find +/// In the case of a nested projection like `<<A as Foo>::FooT as Bar>::BarT`, we may find /// that the definition of `Foo` has some clues: /// /// ```ignore (illustrative) @@ -1489,7 +1497,7 @@ fn assemble_candidates_from_predicates<'cx, 'tcx>( candidate_set.push_candidate(ctor(data)); if potentially_unnormalized_candidates - && !obligation.predicate.has_infer_types_or_consts() + && !obligation.predicate.has_non_region_infer() { // HACK: Pick the first trait def candidate for a fully // inferred predicate. This is to allow duplicates that @@ -1751,8 +1759,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>( super::ImplSource::AutoImpl(..) | super::ImplSource::Builtin(..) | super::ImplSource::TraitUpcasting(_) - | super::ImplSource::ConstDestruct(_) - | super::ImplSource::Tuple => { + | super::ImplSource::ConstDestruct(_) => { // These traits have no associated types. selcx.tcx().sess.delay_span_bug( obligation.cause.span, @@ -1793,9 +1800,18 @@ fn confirm_candidate<'cx, 'tcx>( ProjectionCandidate::Select(impl_source) => { confirm_select_candidate(selcx, obligation, impl_source) } - ProjectionCandidate::ImplTraitInTrait(data) => { + ProjectionCandidate::ImplTraitInTrait(ImplTraitInTraitCandidate::Impl(data)) => { confirm_impl_trait_in_trait_candidate(selcx, obligation, data) } + // If we're projecting an RPITIT for a default trait body, that's just + // the same def-id, but as an opaque type (with regular RPIT semantics). + ProjectionCandidate::ImplTraitInTrait(ImplTraitInTraitCandidate::Trait) => Progress { + term: selcx + .tcx() + .mk_opaque(obligation.predicate.item_def_id, obligation.predicate.substs) + .into(), + obligations: vec![], + }, }; // When checking for cycle during evaluation, we compare predicates with @@ -1830,8 +1846,7 @@ fn confirm_select_candidate<'cx, 'tcx>( | super::ImplSource::Builtin(..) | super::ImplSource::TraitUpcasting(_) | super::ImplSource::TraitAlias(..) - | super::ImplSource::ConstDestruct(_) - | super::ImplSource::Tuple => { + | super::ImplSource::ConstDestruct(_) => { // we don't create Select candidates with this kind of resolution span_bug!( obligation.cause.span, @@ -2142,15 +2157,15 @@ fn confirm_impl_candidate<'cx, 'tcx>( let identity_substs = crate::traits::InternalSubsts::identity_for_item(tcx, assoc_ty.item.def_id); let did = ty::WithOptConstParam::unknown(assoc_ty.item.def_id); - let kind = ty::ConstKind::Unevaluated(ty::Unevaluated::new(did, identity_substs)); + let kind = ty::ConstKind::Unevaluated(ty::UnevaluatedConst::new(did, identity_substs)); ty.map_bound(|ty| tcx.mk_const(ty::ConstS { ty, kind }).into()) } else { ty.map_bound(|ty| ty.into()) }; - if substs.len() != tcx.generics_of(assoc_ty.item.def_id).count() { + if !check_substs_compatible(tcx, &assoc_ty.item, substs) { let err = tcx.ty_error_with_message( obligation.cause.span, - "impl item and trait item have different parameter counts", + "impl item and trait item have different parameters", ); Progress { term: err.into(), obligations: nested } } else { @@ -2159,6 +2174,44 @@ fn confirm_impl_candidate<'cx, 'tcx>( } } +// Verify that the trait item and its implementation have compatible substs lists +fn check_substs_compatible<'tcx>( + tcx: TyCtxt<'tcx>, + assoc_ty: &ty::AssocItem, + substs: ty::SubstsRef<'tcx>, +) -> bool { + fn check_substs_compatible_inner<'tcx>( + tcx: TyCtxt<'tcx>, + generics: &'tcx ty::Generics, + args: &'tcx [ty::GenericArg<'tcx>], + ) -> bool { + if generics.count() != args.len() { + return false; + } + + let (parent_args, own_args) = args.split_at(generics.parent_count); + + if let Some(parent) = generics.parent + && let parent_generics = tcx.generics_of(parent) + && !check_substs_compatible_inner(tcx, parent_generics, parent_args) { + return false; + } + + for (param, arg) in std::iter::zip(&generics.params, own_args) { + match (¶m.kind, arg.unpack()) { + (ty::GenericParamDefKind::Type { .. }, ty::GenericArgKind::Type(_)) + | (ty::GenericParamDefKind::Lifetime, ty::GenericArgKind::Lifetime(_)) + | (ty::GenericParamDefKind::Const { .. }, ty::GenericArgKind::Const(_)) => {} + _ => return false, + } + } + + true + } + + check_substs_compatible_inner(tcx, tcx.generics_of(assoc_ty.def_id), substs.as_slice()) +} + fn confirm_impl_trait_in_trait_candidate<'tcx>( selcx: &mut SelectionContext<'_, 'tcx>, obligation: &ProjectionTyObligation<'tcx>, @@ -2175,8 +2228,21 @@ fn confirm_impl_trait_in_trait_candidate<'tcx>( return Progress { term: tcx.ty_error().into(), obligations }; } + // Use the default `impl Trait` for the trait, e.g., for a default trait body + if leaf_def.item.container == ty::AssocItemContainer::TraitContainer { + return Progress { + term: tcx + .mk_opaque(obligation.predicate.item_def_id, obligation.predicate.substs) + .into(), + obligations, + }; + } + let impl_fn_def_id = leaf_def.item.def_id; - let impl_fn_substs = obligation.predicate.substs.rebase_onto(tcx, trait_fn_def_id, data.substs); + // Rebase from {trait}::{fn}::{opaque} to {impl}::{fn}::{opaque}, + // since `data.substs` are the impl substs. + let impl_fn_substs = + obligation.predicate.substs.rebase_onto(tcx, tcx.parent(trait_fn_def_id), data.substs); let cause = ObligationCause::new( obligation.cause.span, |