diff options
Diffstat (limited to 'compiler/rustc_hir_analysis')
5 files changed, 70 insertions, 18 deletions
diff --git a/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs b/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs index 0df5a57bc2c..4823472cf96 100644 --- a/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs +++ b/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs @@ -144,6 +144,7 @@ impl<'tcx> InherentCollect<'tcx> { let id = id.owner_id.def_id; let item_span = self.tcx.def_span(id); let self_ty = self.tcx.type_of(id).instantiate_identity(); + let self_ty = peel_off_weak_aliases(self.tcx, self_ty); match *self_ty.kind() { ty::Adt(def, _) => self.check_def_id(id, self_ty, def.did()), ty::Foreign(did) => self.check_def_id(id, self_ty, did), @@ -166,7 +167,7 @@ impl<'tcx> InherentCollect<'tcx> { | ty::Never | ty::FnPtr(_) | ty::Tuple(..) => self.check_primitive_impl(id, self_ty), - ty::Alias(..) | ty::Param(_) => { + ty::Alias(ty::Projection | ty::Inherent | ty::Opaque, _) | ty::Param(_) => { Err(self.tcx.dcx().emit_err(errors::InherentNominal { span: item_span })) } ty::FnDef(..) @@ -174,6 +175,7 @@ impl<'tcx> InherentCollect<'tcx> { | ty::CoroutineClosure(..) | ty::Coroutine(..) | ty::CoroutineWitness(..) + | ty::Alias(ty::Weak, _) | ty::Bound(..) | ty::Placeholder(_) | ty::Infer(_) => { @@ -184,3 +186,30 @@ impl<'tcx> InherentCollect<'tcx> { } } } + +/// Peel off all weak alias types in this type until there are none left. +/// +/// <div class="warning"> +/// +/// This assumes that `ty` gets normalized later and that any overflows occurring +/// during said normalization get reported. +/// +/// </div> +fn peel_off_weak_aliases<'tcx>(tcx: TyCtxt<'tcx>, mut ty: Ty<'tcx>) -> Ty<'tcx> { + let ty::Alias(ty::Weak, _) = ty.kind() else { return ty }; + + let limit = tcx.recursion_limit(); + let mut depth = 0; + + while let ty::Alias(ty::Weak, alias) = ty.kind() { + if !limit.value_within_limit(depth) { + let guar = tcx.dcx().delayed_bug("overflow expanding weak alias type"); + return Ty::new_error(tcx, guar); + } + + ty = tcx.type_of(alias.def_id).instantiate(tcx, alias.args); + depth += 1; + } + + ty +} diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs index 05755f98f20..351ac2eb770 100644 --- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs +++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs @@ -307,7 +307,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen tcx, &mut predicates, trait_ref, - &mut cgp::parameters_for_impl(self_ty, trait_ref), + &mut cgp::parameters_for_impl(tcx, self_ty, trait_ref), ); } diff --git a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs index 05efad3ccb3..4ce43bb4887 100644 --- a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs +++ b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs @@ -1,4 +1,5 @@ use rustc_data_structures::fx::FxHashSet; +use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor}; use rustc_middle::ty::{self, Ty, TyCtxt}; use rustc_span::Span; @@ -27,12 +28,13 @@ impl From<ty::ParamConst> for Parameter { /// Returns the set of parameters constrained by the impl header. pub fn parameters_for_impl<'tcx>( + tcx: TyCtxt<'tcx>, impl_self_ty: Ty<'tcx>, impl_trait_ref: Option<ty::TraitRef<'tcx>>, ) -> FxHashSet<Parameter> { let vec = match impl_trait_ref { - Some(tr) => parameters_for(&tr, false), - None => parameters_for(&impl_self_ty, false), + Some(tr) => parameters_for(tcx, &tr, false), + None => parameters_for(tcx, &impl_self_ty, false), }; vec.into_iter().collect() } @@ -43,26 +45,47 @@ pub fn parameters_for_impl<'tcx>( /// of parameters whose values are needed in order to constrain `ty` - these /// differ, with the latter being a superset, in the presence of projections. pub fn parameters_for<'tcx>( + tcx: TyCtxt<'tcx>, t: &impl TypeVisitable<TyCtxt<'tcx>>, include_nonconstraining: bool, ) -> Vec<Parameter> { - let mut collector = ParameterCollector { parameters: vec![], include_nonconstraining }; + let mut collector = + ParameterCollector { tcx, parameters: vec![], include_nonconstraining, depth: 0 }; t.visit_with(&mut collector); collector.parameters } -struct ParameterCollector { +struct ParameterCollector<'tcx> { + tcx: TyCtxt<'tcx>, parameters: Vec<Parameter>, include_nonconstraining: bool, + depth: usize, } -impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ParameterCollector { +impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ParameterCollector<'tcx> { fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { match *t.kind() { - ty::Alias(..) if !self.include_nonconstraining => { - // projections are not injective + ty::Alias(ty::Projection | ty::Inherent | ty::Opaque, _) + if !self.include_nonconstraining => + { + // Projections are not injective in general. return ControlFlow::Continue(()); } + ty::Alias(ty::Weak, alias) if !self.include_nonconstraining => { + if !self.tcx.recursion_limit().value_within_limit(self.depth) { + // Other constituent types may still constrain some generic params, consider + // `<T> (Overflow, T)` for example. Therefore we want to continue instead of + // breaking. Only affects diagnostics. + return ControlFlow::Continue(()); + } + self.depth += 1; + return ensure_sufficient_stack(|| { + self.tcx + .type_of(alias.def_id) + .instantiate(self.tcx, alias.args) + .visit_with(self) + }); + } ty::Param(data) => { self.parameters.push(Parameter::from(data)); } @@ -82,7 +105,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ParameterCollector { fn visit_const(&mut self, c: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> { match c.kind() { ty::ConstKind::Unevaluated(..) if !self.include_nonconstraining => { - // Constant expressions are not injective + // Constant expressions are not injective in general. return c.ty().visit_with(self); } ty::ConstKind::Param(data) => { @@ -201,12 +224,12 @@ pub fn setup_constraining_predicates<'tcx>( // `<<T as Bar>::Baz as Iterator>::Output = <U as Iterator>::Output` // Then the projection only applies if `T` is known, but it still // does not determine `U`. - let inputs = parameters_for(&projection.projection_ty, true); + let inputs = parameters_for(tcx, &projection.projection_ty, true); let relies_only_on_inputs = inputs.iter().all(|p| input_parameters.contains(p)); if !relies_only_on_inputs { continue; } - input_parameters.extend(parameters_for(&projection.term, false)); + input_parameters.extend(parameters_for(tcx, &projection.term, false)); } else { continue; } diff --git a/compiler/rustc_hir_analysis/src/impl_wf_check.rs b/compiler/rustc_hir_analysis/src/impl_wf_check.rs index c072891e295..b4cec1d9882 100644 --- a/compiler/rustc_hir_analysis/src/impl_wf_check.rs +++ b/compiler/rustc_hir_analysis/src/impl_wf_check.rs @@ -94,7 +94,7 @@ fn enforce_impl_params_are_constrained( let impl_predicates = tcx.predicates_of(impl_def_id); let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).map(ty::EarlyBinder::instantiate_identity); - let mut input_parameters = cgp::parameters_for_impl(impl_self_ty, impl_trait_ref); + let mut input_parameters = cgp::parameters_for_impl(tcx, impl_self_ty, impl_trait_ref); cgp::identify_constrained_generic_params( tcx, impl_predicates, @@ -111,7 +111,7 @@ fn enforce_impl_params_are_constrained( match item.kind { ty::AssocKind::Type => { if item.defaultness(tcx).has_value() { - cgp::parameters_for(&tcx.type_of(def_id).instantiate_identity(), true) + cgp::parameters_for(tcx, &tcx.type_of(def_id).instantiate_identity(), true) } else { vec![] } diff --git a/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs b/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs index c8dedb0f371..bd4fce81377 100644 --- a/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs +++ b/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs @@ -266,15 +266,15 @@ fn unconstrained_parent_impl_args<'tcx>( continue; } - unconstrained_parameters.extend(cgp::parameters_for(&projection_ty, true)); + unconstrained_parameters.extend(cgp::parameters_for(tcx, &projection_ty, true)); - for param in cgp::parameters_for(&projected_ty, false) { + for param in cgp::parameters_for(tcx, &projected_ty, false) { if !unconstrained_parameters.contains(¶m) { constrained_params.insert(param.0); } } - unconstrained_parameters.extend(cgp::parameters_for(&projected_ty, true)); + unconstrained_parameters.extend(cgp::parameters_for(tcx, &projected_ty, true)); } } @@ -312,7 +312,7 @@ fn check_duplicate_params<'tcx>( parent_args: &Vec<GenericArg<'tcx>>, span: Span, ) -> Result<(), ErrorGuaranteed> { - let mut base_params = cgp::parameters_for(parent_args, true); + let mut base_params = cgp::parameters_for(tcx, parent_args, true); base_params.sort_by_key(|param| param.0); if let (_, [duplicate, ..]) = base_params.partition_dedup() { let param = impl1_args[duplicate.0 as usize]; |