diff options
Diffstat (limited to 'compiler/rustc_hir_analysis/src/check/compare_impl_item.rs')
| -rw-r--r-- | compiler/rustc_hir_analysis/src/check/compare_impl_item.rs | 121 |
1 files changed, 106 insertions, 15 deletions
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs index bd0ab6463..d081b0e35 100644 --- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs +++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs @@ -14,11 +14,12 @@ use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKi use rustc_infer::infer::{self, InferCtxt, TyCtxtInferExt}; use rustc_infer::traits::util; use rustc_middle::ty::error::{ExpectedFound, TypeError}; +use rustc_middle::ty::fold::BottomUpFolder; use rustc_middle::ty::util::ExplicitSelf; use rustc_middle::ty::{ self, GenericArgs, Ty, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitableExt, }; -use rustc_middle::ty::{GenericParamDefKind, ToPredicate, TyCtxt}; +use rustc_middle::ty::{GenericParamDefKind, TyCtxt}; use rustc_span::{Span, DUMMY_SP}; use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt; use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _; @@ -28,6 +29,8 @@ use rustc_trait_selection::traits::{ use std::borrow::Cow; use std::iter; +mod refine; + /// Checks that a method from an impl conforms to the signature of /// the same method as declared in the trait. /// @@ -53,6 +56,12 @@ pub(super) fn compare_impl_method<'tcx>( impl_trait_ref, CheckImpliedWfMode::Check, )?; + refine::check_refining_return_position_impl_trait_in_trait( + tcx, + impl_m, + trait_m, + impl_trait_ref, + ); }; } @@ -587,7 +596,7 @@ fn compare_asyncness<'tcx>( trait_m: ty::AssocItem, delay: bool, ) -> Result<(), ErrorGuaranteed> { - if tcx.asyncness(trait_m.def_id) == hir::IsAsync::Async { + if tcx.asyncness(trait_m.def_id).is_async() { match tcx.fn_sig(impl_m.def_id).skip_binder().skip_binder().output().kind() { ty::Alias(ty::Opaque, ..) => { // allow both `async fn foo()` and `fn foo() -> impl Future` @@ -653,8 +662,6 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>( let trait_m = tcx.opt_associated_item(impl_m.trait_item_def_id.unwrap()).unwrap(); let impl_trait_ref = tcx.impl_trait_ref(impl_m.impl_container(tcx).unwrap()).unwrap().instantiate_identity(); - let param_env = tcx.param_env(impl_m_def_id); - // First, check a few of the same things as `compare_impl_method`, // just so we don't ICE during substitution later. check_method_is_structurally_compatible(tcx, impl_m, trait_m, impl_trait_ref, true)?; @@ -680,13 +687,26 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>( let trait_to_placeholder_args = impl_to_placeholder_args.rebase_onto(tcx, impl_m.container_id(tcx), trait_to_impl_args); + let hybrid_preds = tcx + .predicates_of(impl_m.container_id(tcx)) + .instantiate_identity(tcx) + .into_iter() + .chain(tcx.predicates_of(trait_m.def_id).instantiate_own(tcx, trait_to_placeholder_args)) + .map(|(clause, _)| clause); + let param_env = ty::ParamEnv::new(tcx.mk_clauses_from_iter(hybrid_preds), Reveal::UserFacing); + let param_env = traits::normalize_param_env_or_error( + tcx, + param_env, + ObligationCause::misc(tcx.def_span(impl_m_def_id), impl_m_def_id), + ); + let infcx = &tcx.infer_ctxt().build(); let ocx = ObligationCtxt::new(infcx); // Normalize the impl signature with fresh variables for lifetime inference. - let norm_cause = ObligationCause::misc(return_span, impl_m_def_id); + let misc_cause = ObligationCause::misc(return_span, impl_m_def_id); let impl_sig = ocx.normalize( - &norm_cause, + &misc_cause, param_env, tcx.liberate_late_bound_regions( impl_m.def_id, @@ -717,12 +737,68 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>( ); } - let trait_sig = ocx.normalize(&norm_cause, param_env, unnormalized_trait_sig); + let trait_sig = ocx.normalize(&misc_cause, param_env, unnormalized_trait_sig); trait_sig.error_reported()?; let trait_return_ty = trait_sig.output(); + // RPITITs are allowed to use the implied predicates of the method that + // defines them. This is because we want code like: + // ``` + // trait Foo { + // fn test<'a, T>(_: &'a T) -> impl Sized; + // } + // impl Foo for () { + // fn test<'a, T>(x: &'a T) -> &'a T { x } + // } + // ``` + // .. to compile. However, since we use both the normalized and unnormalized + // inputs and outputs from the substituted trait signature, we will end up + // seeing the hidden type of an RPIT in the signature itself. Naively, this + // means that we will use the hidden type to imply the hidden type's own + // well-formedness. + // + // To avoid this, we replace the infer vars used for hidden type inference + // with placeholders, which imply nothing about outlives bounds, and then + // prove below that the hidden types are well formed. + let universe = infcx.create_next_universe(); + let mut idx = 0; + let mapping: FxHashMap<_, _> = collector + .types + .iter() + .map(|(_, &(ty, _))| { + assert!( + infcx.resolve_vars_if_possible(ty) == ty && ty.is_ty_var(), + "{ty:?} should not have been constrained via normalization", + ty = infcx.resolve_vars_if_possible(ty) + ); + idx += 1; + ( + ty, + Ty::new_placeholder( + tcx, + ty::Placeholder { + universe, + bound: ty::BoundTy { + var: ty::BoundVar::from_usize(idx), + kind: ty::BoundTyKind::Anon, + }, + }, + ), + ) + }) + .collect(); + let mut type_mapper = BottomUpFolder { + tcx, + ty_op: |ty| *mapping.get(&ty).unwrap_or(&ty), + lt_op: |lt| lt, + ct_op: |ct| ct, + }; let wf_tys = FxIndexSet::from_iter( - unnormalized_trait_sig.inputs_and_output.iter().chain(trait_sig.inputs_and_output.iter()), + unnormalized_trait_sig + .inputs_and_output + .iter() + .chain(trait_sig.inputs_and_output.iter()) + .map(|ty| ty.fold_with(&mut type_mapper)), ); match ocx.eq(&cause, param_env, trait_return_ty, impl_return_ty) { @@ -779,6 +855,20 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>( } } + // FIXME: This has the same issue as #108544, but since this isn't breaking + // existing code, I'm not particularly inclined to do the same hack as above + // where we process wf obligations manually. This can be fixed in a forward- + // compatible way later. + let collected_types = collector.types; + for (_, &(ty, _)) in &collected_types { + ocx.register_obligation(traits::Obligation::new( + tcx, + misc_cause.clone(), + param_env, + ty::ClauseKind::WellFormed(ty.into()), + )); + } + // Check that all obligations are satisfied by the implementation's // RPITs. let errors = ocx.select_all_or_error(); @@ -787,8 +877,6 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>( return Err(reported); } - let collected_types = collector.types; - // Finally, resolve all regions. This catches wily misuses of // lifetime parameters. let outlives_env = OutlivesEnvironment::with_bounds( @@ -1126,7 +1214,10 @@ fn report_trait_method_mismatch<'tcx>( &mut diag, &cause, trait_err_span.map(|sp| (sp, Cow::from("type in trait"))), - Some(infer::ValuePairs::Sigs(ExpectedFound { expected: trait_sig, found: impl_sig })), + Some(infer::ValuePairs::PolySigs(ExpectedFound { + expected: ty::Binder::dummy(trait_sig), + found: ty::Binder::dummy(impl_sig), + })), terr, false, false, @@ -2188,16 +2279,16 @@ pub(super) fn check_type_bounds<'tcx>( // // impl<T> X for T where T: X { type Y = <T as X>::Y; } } - _ => predicates.push( + _ => predicates.push(ty::Clause::from_projection_clause( + tcx, ty::Binder::bind_with_vars( ty::ProjectionPredicate { projection_ty: tcx.mk_alias_ty(trait_ty.def_id, rebased_args), term: normalize_impl_ty.into(), }, bound_vars, - ) - .to_predicate(tcx), - ), + ), + )), }; ty::ParamEnv::new(tcx.mk_clauses(&predicates), Reveal::UserFacing) }; |