From 05ce209d20232f6d933421f8b8ac58d94557a2aa Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Le=C3=B3n=20Orell=20Valerian=20Liehr?= Date: Tue, 20 Feb 2024 10:34:51 +0100 Subject: [PATCH 1/5] Rename some normalization-related items --- compiler/rustc_middle/src/arena.rs | 2 +- compiler/rustc_middle/src/query/mod.rs | 32 ++++++++++++------ compiler/rustc_middle/src/traits/query.rs | 6 ++-- .../src/traits/normalize.rs | 2 -- .../src/traits/query/normalize.rs | 16 ++++----- .../src/normalize_projection_ty.rs | 33 ++++++++++--------- 6 files changed, 51 insertions(+), 40 deletions(-) diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs index c648b2bfe9b..a532635669d 100644 --- a/compiler/rustc_middle/src/arena.rs +++ b/compiler/rustc_middle/src/arena.rs @@ -47,7 +47,7 @@ macro_rules! arena_types { rustc_middle::traits::query::DropckOutlivesResult<'tcx> > >, - [] normalize_projection_ty: + [] normalize_canonicalized_projection_ty: rustc_middle::infer::canonical::Canonical<'tcx, rustc_middle::infer::canonical::QueryResponse<'tcx, rustc_middle::traits::query::NormalizationResult<'tcx> diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs index 5be45c33e11..c931d2e5313 100644 --- a/compiler/rustc_middle/src/query/mod.rs +++ b/compiler/rustc_middle/src/query/mod.rs @@ -31,7 +31,7 @@ }; use crate::thir; use crate::traits::query::{ - CanonicalPredicateGoal, CanonicalProjectionGoal, CanonicalTyGoal, + CanonicalAliasGoal, CanonicalPredicateGoal, CanonicalTyGoal, CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal, CanonicalTypeOpProvePredicateGoal, CanonicalTypeOpSubtypeGoal, NoSolution, }; @@ -1931,9 +1931,13 @@ arena_cache } - /// Do not call this query directly: invoke `normalize` instead. - query normalize_projection_ty( - goal: CanonicalProjectionGoal<'tcx> + ///
+ /// + /// Do not call this query directly: Invoke `normalize` instead. + /// + ///
+ query normalize_canonicalized_projection_ty( + goal: CanonicalAliasGoal<'tcx> ) -> Result< &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution, @@ -1941,9 +1945,13 @@ desc { "normalizing `{}`", goal.value.value } } - /// Do not call this query directly: invoke `normalize` instead. - query normalize_weak_ty( - goal: CanonicalProjectionGoal<'tcx> + ///
+ /// + /// Do not call this query directly: Invoke `normalize` instead. + /// + ///
+ query normalize_canonicalized_weak_ty( + goal: CanonicalAliasGoal<'tcx> ) -> Result< &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution, @@ -1951,9 +1959,13 @@ desc { "normalizing `{}`", goal.value.value } } - /// Do not call this query directly: invoke `normalize` instead. - query normalize_inherent_projection_ty( - goal: CanonicalProjectionGoal<'tcx> + ///
+ /// + /// Do not call this query directly: Invoke `normalize` instead. + /// + ///
+ query normalize_canonicalized_inherent_projection_ty( + goal: CanonicalAliasGoal<'tcx> ) -> Result< &'tcx Canonical<'tcx, canonical::QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution, diff --git a/compiler/rustc_middle/src/traits/query.rs b/compiler/rustc_middle/src/traits/query.rs index 61d96cad57d..12e4f70ba57 100644 --- a/compiler/rustc_middle/src/traits/query.rs +++ b/compiler/rustc_middle/src/traits/query.rs @@ -67,7 +67,7 @@ pub fn new(value: T) -> Self { } } -pub type CanonicalProjectionGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, ty::AliasTy<'tcx>>>; +pub type CanonicalAliasGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, ty::AliasTy<'tcx>>>; pub type CanonicalTyGoal<'tcx> = Canonical<'tcx, ty::ParamEnvAnd<'tcx, Ty<'tcx>>>; @@ -177,10 +177,10 @@ pub struct MethodAutoderefBadTy<'tcx> { pub ty: Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, } -/// Result from the `normalize_projection_ty` query. +/// Result of the `normalize_canonicalized_{{,inherent_}projection,weak}_ty` queries. #[derive(Clone, Debug, HashStable, TypeFoldable, TypeVisitable)] pub struct NormalizationResult<'tcx> { - /// Result of normalization. + /// Result of the normalization. pub normalized_ty: Ty<'tcx>, } diff --git a/compiler/rustc_trait_selection/src/traits/normalize.rs b/compiler/rustc_trait_selection/src/traits/normalize.rs index ac62f875fb9..f37d917b4a0 100644 --- a/compiler/rustc_trait_selection/src/traits/normalize.rs +++ b/compiler/rustc_trait_selection/src/traits/normalize.rs @@ -355,8 +355,6 @@ fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { let data = data.fold_with(self); - // FIXME(inherent_associated_types): Do we need to honor `self.eager_inference_replacement` - // here like `ty::Projection`? project::normalize_inherent_projection( self.selcx, self.param_env, diff --git a/compiler/rustc_trait_selection/src/traits/query/normalize.rs b/compiler/rustc_trait_selection/src/traits/query/normalize.rs index 26da065246d..70fd0b7e50b 100644 --- a/compiler/rustc_trait_selection/src/traits/query/normalize.rs +++ b/compiler/rustc_trait_selection/src/traits/query/normalize.rs @@ -1,6 +1,6 @@ //! Code for the 'normalization' query. This consists of a wrapper //! which folds deeply, invoking the underlying -//! `normalize_projection_ty` query when it encounters projections. +//! `normalize_canonicalized_projection_ty` query when it encounters projections. use crate::infer::at::At; use crate::infer::canonical::OriginalQueryValues; @@ -271,9 +271,9 @@ fn try_fold_ty(&mut self, ty: Ty<'tcx>) -> Result, Self::Error> { debug!("QueryNormalizer: c_data = {:#?}", c_data); debug!("QueryNormalizer: orig_values = {:#?}", orig_values); let result = match kind { - ty::Projection => tcx.normalize_projection_ty(c_data), - ty::Weak => tcx.normalize_weak_ty(c_data), - ty::Inherent => tcx.normalize_inherent_projection_ty(c_data), + ty::Projection => tcx.normalize_canonicalized_projection_ty(c_data), + ty::Weak => tcx.normalize_canonicalized_weak_ty(c_data), + ty::Inherent => tcx.normalize_canonicalized_inherent_projection_ty(c_data), kind => unreachable!("did not expect {kind:?} due to match arm above"), }?; // We don't expect ambiguity. @@ -308,10 +308,10 @@ fn try_fold_ty(&mut self, ty: Ty<'tcx>) -> Result, Self::Error> { } else { result.normalized_ty }; - // `tcx.normalize_projection_ty` may normalize to a type that still has - // unevaluated consts, so keep normalizing here if that's the case. - // Similarly, `tcx.normalize_weak_ty` will only unwrap one layer of type - // and we need to continue folding it to reveal the TAIT behind it. + // `tcx.normalize_canonicalized_projection_ty` may normalize to a type that + // still has unevaluated consts, so keep normalizing here if that's the case. + // Similarly, `tcx.normalize_canonicalized_weak_ty` will only unwrap one layer + // of type and we need to continue folding it to reveal the TAIT behind it. if res != ty && (res.has_type_flags(ty::TypeFlags::HAS_CT_PROJECTION) || kind == ty::Weak) { diff --git a/compiler/rustc_traits/src/normalize_projection_ty.rs b/compiler/rustc_traits/src/normalize_projection_ty.rs index 94df28a1454..92a19fb9119 100644 --- a/compiler/rustc_traits/src/normalize_projection_ty.rs +++ b/compiler/rustc_traits/src/normalize_projection_ty.rs @@ -5,7 +5,7 @@ use rustc_trait_selection::infer::InferCtxtBuilderExt; use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt; use rustc_trait_selection::traits::query::{ - normalize::NormalizationResult, CanonicalProjectionGoal, NoSolution, + normalize::NormalizationResult, CanonicalAliasGoal, NoSolution, }; use rustc_trait_selection::traits::{ self, FulfillmentErrorCode, ObligationCause, SelectionContext, @@ -13,18 +13,19 @@ pub(crate) fn provide(p: &mut Providers) { *p = Providers { - normalize_projection_ty, - normalize_weak_ty, - normalize_inherent_projection_ty, + normalize_canonicalized_projection_ty, + normalize_canonicalized_weak_ty, + normalize_canonicalized_inherent_projection_ty, ..*p }; } -fn normalize_projection_ty<'tcx>( +fn normalize_canonicalized_projection_ty<'tcx>( tcx: TyCtxt<'tcx>, - goal: CanonicalProjectionGoal<'tcx>, + goal: CanonicalAliasGoal<'tcx>, ) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> { - debug!("normalize_provider(goal={:#?})", goal); + debug!("normalize_canonicalized_projection_ty(goal={:#?})", goal); + tcx.infer_ctxt().enter_canonical_trait_query( &goal, |ocx, ParamEnvAnd { param_env, value: goal }| { @@ -61,19 +62,19 @@ fn normalize_projection_ty<'tcx>( return Err(NoSolution); } - // FIXME(associated_const_equality): All users of normalize_projection_ty expected - // a type, but there is the possibility it could've been a const now. Maybe change - // it to a Term later? + // FIXME(associated_const_equality): All users of normalize_canonicalized_projection_ty + // expected a type, but there is the possibility it could've been a const now. + // Maybe change it to a Term later? Ok(NormalizationResult { normalized_ty: answer.ty().unwrap() }) }, ) } -fn normalize_weak_ty<'tcx>( +fn normalize_canonicalized_weak_ty<'tcx>( tcx: TyCtxt<'tcx>, - goal: CanonicalProjectionGoal<'tcx>, + goal: CanonicalAliasGoal<'tcx>, ) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> { - debug!("normalize_provider(goal={:#?})", goal); + debug!("normalize_canonicalized_weak_ty(goal={:#?})", goal); tcx.infer_ctxt().enter_canonical_trait_query( &goal, @@ -95,11 +96,11 @@ fn normalize_weak_ty<'tcx>( ) } -fn normalize_inherent_projection_ty<'tcx>( +fn normalize_canonicalized_inherent_projection_ty<'tcx>( tcx: TyCtxt<'tcx>, - goal: CanonicalProjectionGoal<'tcx>, + goal: CanonicalAliasGoal<'tcx>, ) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> { - debug!("normalize_provider(goal={:#?})", goal); + debug!("normalize_canonicalized_inherent_projection_ty(goal={:#?})", goal); tcx.infer_ctxt().enter_canonical_trait_query( &goal, From 515d805a0e76b57853bf9e929a2e7b084c475824 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Le=C3=B3n=20Orell=20Valerian=20Liehr?= Date: Tue, 20 Feb 2024 12:38:23 +0100 Subject: [PATCH 2/5] Introduce expand_weak_alias_tys --- compiler/rustc_middle/src/ty/flags.rs | 5 +- compiler/rustc_middle/src/ty/util.rs | 61 +++++++++++++++++++ compiler/rustc_middle/src/ty/visit.rs | 25 ++++---- .../src/traits/normalize.rs | 20 +++--- compiler/rustc_type_ir/src/flags.rs | 31 +++++----- .../constrained-late-bound-regions.rs | 15 +++++ ...arams.rs => constrained-params-in-impl.rs} | 0 .../unconstrained-late-bound-regions.rs | 23 +++++++ .../unconstrained-late-bound-regions.stderr | 22 +++++++ ...trained-params-in-impl-due-to-overflow.rs} | 0 ...ned-params-in-impl-due-to-overflow.stderr} | 2 +- ...ams.rs => unconstrained-params-in-impl.rs} | 0 ...rr => unconstrained-params-in-impl.stderr} | 2 +- 13 files changed, 165 insertions(+), 41 deletions(-) create mode 100644 tests/ui/lazy-type-alias/constrained-late-bound-regions.rs rename tests/ui/lazy-type-alias/{constrained-params.rs => constrained-params-in-impl.rs} (100%) create mode 100644 tests/ui/lazy-type-alias/unconstrained-late-bound-regions.rs create mode 100644 tests/ui/lazy-type-alias/unconstrained-late-bound-regions.stderr rename tests/ui/lazy-type-alias/{unconstrained-param-due-to-overflow.rs => unconstrained-params-in-impl-due-to-overflow.rs} (100%) rename tests/ui/lazy-type-alias/{unconstrained-param-due-to-overflow.stderr => unconstrained-params-in-impl-due-to-overflow.stderr} (81%) rename tests/ui/lazy-type-alias/{unconstrained-params.rs => unconstrained-params-in-impl.rs} (100%) rename tests/ui/lazy-type-alias/{unconstrained-params.stderr => unconstrained-params-in-impl.stderr} (85%) diff --git a/compiler/rustc_middle/src/ty/flags.rs b/compiler/rustc_middle/src/ty/flags.rs index 0f4b5fe228c..18cf5445e56 100644 --- a/compiler/rustc_middle/src/ty/flags.rs +++ b/compiler/rustc_middle/src/ty/flags.rs @@ -181,9 +181,10 @@ fn add_kind(&mut self, kind: &ty::TyKind<'_>) { &ty::Alias(kind, data) => { self.add_flags(match kind { - ty::Weak | ty::Projection => TypeFlags::HAS_TY_PROJECTION, - ty::Inherent => TypeFlags::HAS_TY_INHERENT, + ty::Projection => TypeFlags::HAS_TY_PROJECTION, + ty::Weak => TypeFlags::HAS_TY_WEAK, ty::Opaque => TypeFlags::HAS_TY_OPAQUE, + ty::Inherent => TypeFlags::HAS_TY_INHERENT, }); self.add_alias_ty(data); diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs index 3f539945841..ff9d1ed6ae9 100644 --- a/compiler/rustc_middle/src/ty/util.rs +++ b/compiler/rustc_middle/src/ty/util.rs @@ -11,6 +11,7 @@ use rustc_apfloat::Float as _; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_data_structures::stable_hasher::{Hash128, HashStable, StableHasher}; +use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_errors::ErrorGuaranteed; use rustc_hir as hir; use rustc_hir::def::{CtorOf, DefKind, Res}; @@ -867,6 +868,30 @@ pub fn with_opt_host_effect_param( self.mk_args_from_iter(args.into_iter().map(|arg| arg.into()).chain(opt_const_param)) } + + /// Expand any [weak alias types][weak] contained within the given `value`. + /// + /// This should be used over other normalization routines in situations where + /// it's important not to normalize other alias types and where the predicates + /// on the corresponding type alias shouldn't be taken into consideration. + /// + /// Whenever possible **prefer not to use this function**! Instead, use standard + /// normalization routines or if feasible don't normalize at all. + /// + /// This function comes in handy if you want to mimic the behavior of eager + /// type alias expansion in a localized manner. + /// + ///
+ /// This delays a bug on overflow! Therefore you need to be certain that the + /// contained types get fully normalized at a later stage. Note that even on + /// overflow all well-behaved weak alias types get expanded correctly, so the + /// result is still useful. + ///
+ /// + /// [weak]: ty::Weak + pub fn expand_weak_alias_tys>>(self, value: T) -> T { + value.fold_with(&mut WeakAliasTypeExpander { tcx: self, depth: 0 }) + } } struct OpaqueTypeExpander<'tcx> { @@ -1002,6 +1027,42 @@ fn fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> { } } +struct WeakAliasTypeExpander<'tcx> { + tcx: TyCtxt<'tcx>, + depth: usize, +} + +impl<'tcx> TypeFolder> for WeakAliasTypeExpander<'tcx> { + fn interner(&self) -> TyCtxt<'tcx> { + self.tcx + } + + fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { + if !ty.has_type_flags(ty::TypeFlags::HAS_TY_WEAK) { + return ty; + } + let ty::Alias(ty::Weak, alias) = ty.kind() else { + return ty.super_fold_with(self); + }; + if !self.tcx.recursion_limit().value_within_limit(self.depth) { + let guar = self.tcx.dcx().delayed_bug("overflow expanding weak alias type"); + return Ty::new_error(self.tcx, guar); + } + + self.depth += 1; + ensure_sufficient_stack(|| { + self.tcx.type_of(alias.def_id).instantiate(self.tcx, alias.args).fold_with(self) + }) + } + + fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> { + if !ct.ty().has_type_flags(ty::TypeFlags::HAS_TY_WEAK) { + return ct; + } + ct.super_fold_with(self) + } +} + impl<'tcx> Ty<'tcx> { /// Returns the `Size` for primitive types (bool, uint, int, char, float). pub fn primitive_size(self, tcx: TyCtxt<'tcx>) -> Size { diff --git a/compiler/rustc_middle/src/ty/visit.rs b/compiler/rustc_middle/src/ty/visit.rs index 59292a281ed..1de2ceecae7 100644 --- a/compiler/rustc_middle/src/ty/visit.rs +++ b/compiler/rustc_middle/src/ty/visit.rs @@ -131,12 +131,13 @@ pub fn collect_referenced_late_bound_regions( fn collect_late_bound_regions( self, value: &Binder<'tcx, T>, - just_constraint: bool, + just_constrained: bool, ) -> FxHashSet where T: TypeVisitable>, { - let mut collector = LateBoundRegionsCollector::new(just_constraint); + let mut collector = LateBoundRegionsCollector::new(self, just_constrained); + let value = if just_constrained { self.expand_weak_alias_tys(value) } else { value }; let result = value.as_ref().skip_binder().visit_with(&mut collector); assert!(result.is_continue()); // should never have stopped early collector.regions @@ -258,11 +259,7 @@ struct LateBoundRegionsCollector { impl LateBoundRegionsCollector { fn new(just_constrained: bool) -> Self { - LateBoundRegionsCollector { - current_index: ty::INNERMOST, - regions: Default::default(), - just_constrained, - } + Self { current_index: ty::INNERMOST, regions: Default::default(), just_constrained } } } @@ -278,12 +275,16 @@ fn visit_binder>>( } fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow { - // if we are only looking for "constrained" region, we have to - // ignore the inputs to a projection, as they may not appear - // in the normalized form if self.just_constrained { - if let ty::Alias(..) = t.kind() { - return ControlFlow::Continue(()); + match t.kind() { + // If we are only looking for "constrained" regions, we have to ignore the + // inputs to a projection as they may not appear in the normalized form. + ty::Alias(ty::Projection | ty::Inherent | ty::Opaque, _) => { + return ControlFlow::Continue(()); + } + // All weak alias types should've been expanded beforehand. + ty::Alias(ty::Weak, _) => bug!("unexpected weak alias type"), + _ => {} } } diff --git a/compiler/rustc_trait_selection/src/traits/normalize.rs b/compiler/rustc_trait_selection/src/traits/normalize.rs index f37d917b4a0..429e5a5d7a4 100644 --- a/compiler/rustc_trait_selection/src/traits/normalize.rs +++ b/compiler/rustc_trait_selection/src/traits/normalize.rs @@ -101,19 +101,17 @@ pub(super) fn needs_normalization<'tcx, T: TypeVisitable>>( value: &T, reveal: Reveal, ) -> bool { + let mut flags = ty::TypeFlags::HAS_TY_PROJECTION + | ty::TypeFlags::HAS_TY_WEAK + | ty::TypeFlags::HAS_TY_INHERENT + | ty::TypeFlags::HAS_CT_PROJECTION; + match reveal { - Reveal::UserFacing => value.has_type_flags( - ty::TypeFlags::HAS_TY_PROJECTION - | ty::TypeFlags::HAS_TY_INHERENT - | ty::TypeFlags::HAS_CT_PROJECTION, - ), - Reveal::All => value.has_type_flags( - ty::TypeFlags::HAS_TY_PROJECTION - | ty::TypeFlags::HAS_TY_INHERENT - | ty::TypeFlags::HAS_TY_OPAQUE - | ty::TypeFlags::HAS_CT_PROJECTION, - ), + Reveal::UserFacing => {} + Reveal::All => flags |= ty::TypeFlags::HAS_TY_OPAQUE, } + + value.has_type_flags(flags) } struct AssocTypeNormalizer<'a, 'b, 'tcx> { diff --git a/compiler/rustc_type_ir/src/flags.rs b/compiler/rustc_type_ir/src/flags.rs index 1da26cfc242..b38ef2ad84d 100644 --- a/compiler/rustc_type_ir/src/flags.rs +++ b/compiler/rustc_type_ir/src/flags.rs @@ -69,32 +69,35 @@ pub struct TypeFlags: u32 { /// Does this have `Projection`? const HAS_TY_PROJECTION = 1 << 10; - /// Does this have `Inherent`? - const HAS_TY_INHERENT = 1 << 11; + /// Does this have `Weak`? + const HAS_TY_WEAK = 1 << 11; /// Does this have `Opaque`? const HAS_TY_OPAQUE = 1 << 12; + /// Does this have `Inherent`? + const HAS_TY_INHERENT = 1 << 13; /// Does this have `ConstKind::Unevaluated`? - const HAS_CT_PROJECTION = 1 << 13; + const HAS_CT_PROJECTION = 1 << 14; /// Could this type be normalized further? const HAS_PROJECTION = TypeFlags::HAS_TY_PROJECTION.bits() + | TypeFlags::HAS_TY_WEAK.bits() | TypeFlags::HAS_TY_OPAQUE.bits() | TypeFlags::HAS_TY_INHERENT.bits() | TypeFlags::HAS_CT_PROJECTION.bits(); /// Is an error type/const reachable? - const HAS_ERROR = 1 << 14; + const HAS_ERROR = 1 << 15; /// Does this have any region that "appears free" in the type? /// Basically anything but `ReBound` and `ReErased`. - const HAS_FREE_REGIONS = 1 << 15; + const HAS_FREE_REGIONS = 1 << 16; /// Does this have any `ReBound` regions? - const HAS_RE_BOUND = 1 << 16; + const HAS_RE_BOUND = 1 << 17; /// Does this have any `Bound` types? - const HAS_TY_BOUND = 1 << 17; + const HAS_TY_BOUND = 1 << 18; /// Does this have any `ConstKind::Bound` consts? - const HAS_CT_BOUND = 1 << 18; + const HAS_CT_BOUND = 1 << 19; /// Does this have any bound variables? /// Used to check if a global bound is safe to evaluate. const HAS_BOUND_VARS = TypeFlags::HAS_RE_BOUND.bits() @@ -102,22 +105,22 @@ pub struct TypeFlags: u32 { | TypeFlags::HAS_CT_BOUND.bits(); /// Does this have any `ReErased` regions? - const HAS_RE_ERASED = 1 << 19; + const HAS_RE_ERASED = 1 << 20; /// Does this value have parameters/placeholders/inference variables which could be /// replaced later, in a way that would change the results of `impl` specialization? - const STILL_FURTHER_SPECIALIZABLE = 1 << 20; + const STILL_FURTHER_SPECIALIZABLE = 1 << 21; /// Does this value have `InferTy::FreshTy/FreshIntTy/FreshFloatTy`? - const HAS_TY_FRESH = 1 << 21; + const HAS_TY_FRESH = 1 << 22; /// Does this value have `InferConst::Fresh`? - const HAS_CT_FRESH = 1 << 22; + const HAS_CT_FRESH = 1 << 23; /// Does this have `Coroutine` or `CoroutineWitness`? - const HAS_TY_COROUTINE = 1 << 23; + const HAS_TY_COROUTINE = 1 << 24; /// Does this have any binders with bound vars (e.g. that need to be anonymized)? - const HAS_BINDER_VARS = 1 << 24; + const HAS_BINDER_VARS = 1 << 25; } } diff --git a/tests/ui/lazy-type-alias/constrained-late-bound-regions.rs b/tests/ui/lazy-type-alias/constrained-late-bound-regions.rs new file mode 100644 index 00000000000..e759e72d745 --- /dev/null +++ b/tests/ui/lazy-type-alias/constrained-late-bound-regions.rs @@ -0,0 +1,15 @@ +//@ check-pass +// Weak alias types constrain late-bound regions if their normalized form constrains them. + +#![feature(lazy_type_alias)] +#![allow(incomplete_features)] + +type Ref<'a> = &'a (); + +type FnPtr = for<'a> fn(Ref<'a>) -> &'a (); // OK +type DynCl = dyn for<'a> Fn(Ref<'a>) -> &'a (); // OK + +fn map0(_: Ref) -> Ref { &() } // OK +fn map1(_: Ref<'_>) -> Ref<'_> { &() } // OK + +fn main() {} diff --git a/tests/ui/lazy-type-alias/constrained-params.rs b/tests/ui/lazy-type-alias/constrained-params-in-impl.rs similarity index 100% rename from tests/ui/lazy-type-alias/constrained-params.rs rename to tests/ui/lazy-type-alias/constrained-params-in-impl.rs diff --git a/tests/ui/lazy-type-alias/unconstrained-late-bound-regions.rs b/tests/ui/lazy-type-alias/unconstrained-late-bound-regions.rs new file mode 100644 index 00000000000..844570e22d2 --- /dev/null +++ b/tests/ui/lazy-type-alias/unconstrained-late-bound-regions.rs @@ -0,0 +1,23 @@ +// Weak alias types only constrain late-bound regions if their normalized form constrains them. + +#![feature(lazy_type_alias)] +#![allow(incomplete_features)] + +type NotInjective<'a> = <() as Discard>::Output<'a>; + +type FnPtr0 = for<'a> fn(NotInjective<'a>) -> &'a (); +//~^ ERROR references lifetime `'a`, which is not constrained by the fn input types +type FnPtr1 = for<'a> fn(NotInjectiveEither<'a, ()>) -> NotInjectiveEither<'a, ()>; +//~^ ERROR references lifetime `'a`, which is not constrained by the fn input types +type DynCl = dyn for<'a> Fn(NotInjective<'a>) -> &'a (); +//~^ ERROR references lifetime `'a`, which does not appear in the trait input types + +trait Discard { type Output<'a>; } +impl Discard for () { type Output<'_a> = (); } + +type NotInjectiveEither<'a, Linchpin> = Linchpin +where + Linchpin: Fn() -> &'a (); + + +fn main() {} diff --git a/tests/ui/lazy-type-alias/unconstrained-late-bound-regions.stderr b/tests/ui/lazy-type-alias/unconstrained-late-bound-regions.stderr new file mode 100644 index 00000000000..241c7761c60 --- /dev/null +++ b/tests/ui/lazy-type-alias/unconstrained-late-bound-regions.stderr @@ -0,0 +1,22 @@ +error[E0581]: return type references lifetime `'a`, which is not constrained by the fn input types + --> $DIR/unconstrained-late-bound-regions.rs:8:47 + | +LL | type FnPtr0 = for<'a> fn(NotInjective<'a>) -> &'a (); + | ^^^^^^ + +error[E0581]: return type references lifetime `'a`, which is not constrained by the fn input types + --> $DIR/unconstrained-late-bound-regions.rs:10:57 + | +LL | type FnPtr1 = for<'a> fn(NotInjectiveEither<'a, ()>) -> NotInjectiveEither<'a, ()>; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error[E0582]: binding for associated type `Output` references lifetime `'a`, which does not appear in the trait input types + --> $DIR/unconstrained-late-bound-regions.rs:12:50 + | +LL | type DynCl = dyn for<'a> Fn(NotInjective<'a>) -> &'a (); + | ^^^^^^ + +error: aborting due to 3 previous errors + +Some errors have detailed explanations: E0581, E0582. +For more information about an error, try `rustc --explain E0581`. diff --git a/tests/ui/lazy-type-alias/unconstrained-param-due-to-overflow.rs b/tests/ui/lazy-type-alias/unconstrained-params-in-impl-due-to-overflow.rs similarity index 100% rename from tests/ui/lazy-type-alias/unconstrained-param-due-to-overflow.rs rename to tests/ui/lazy-type-alias/unconstrained-params-in-impl-due-to-overflow.rs diff --git a/tests/ui/lazy-type-alias/unconstrained-param-due-to-overflow.stderr b/tests/ui/lazy-type-alias/unconstrained-params-in-impl-due-to-overflow.stderr similarity index 81% rename from tests/ui/lazy-type-alias/unconstrained-param-due-to-overflow.stderr rename to tests/ui/lazy-type-alias/unconstrained-params-in-impl-due-to-overflow.stderr index 9af6f5dda0b..b65c84226ce 100644 --- a/tests/ui/lazy-type-alias/unconstrained-param-due-to-overflow.stderr +++ b/tests/ui/lazy-type-alias/unconstrained-params-in-impl-due-to-overflow.stderr @@ -1,5 +1,5 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates - --> $DIR/unconstrained-param-due-to-overflow.rs:4:6 + --> $DIR/unconstrained-params-in-impl-due-to-overflow.rs:4:6 | LL | impl Loop {} | ^ unconstrained type parameter diff --git a/tests/ui/lazy-type-alias/unconstrained-params.rs b/tests/ui/lazy-type-alias/unconstrained-params-in-impl.rs similarity index 100% rename from tests/ui/lazy-type-alias/unconstrained-params.rs rename to tests/ui/lazy-type-alias/unconstrained-params-in-impl.rs diff --git a/tests/ui/lazy-type-alias/unconstrained-params.stderr b/tests/ui/lazy-type-alias/unconstrained-params-in-impl.stderr similarity index 85% rename from tests/ui/lazy-type-alias/unconstrained-params.stderr rename to tests/ui/lazy-type-alias/unconstrained-params-in-impl.stderr index 3c52a06c319..2419c78cba8 100644 --- a/tests/ui/lazy-type-alias/unconstrained-params.stderr +++ b/tests/ui/lazy-type-alias/unconstrained-params-in-impl.stderr @@ -1,5 +1,5 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates - --> $DIR/unconstrained-params.rs:4:6 + --> $DIR/unconstrained-params-in-impl.rs:4:6 | LL | impl NotInjective {} | ^ unconstrained type parameter From da01cced15b1a59e5eb40bdf5bb0be9a143d4e5a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Le=C3=B3n=20Orell=20Valerian=20Liehr?= Date: Tue, 20 Feb 2024 13:50:39 +0100 Subject: [PATCH 3/5] Expand weak alias types before collecting constrained and referenced late bound regions --- .../rustc_hir_analysis/src/astconv/bounds.rs | 4 ++-- compiler/rustc_hir_analysis/src/astconv/mod.rs | 4 ++-- compiler/rustc_hir_analysis/src/collect.rs | 2 +- .../error_reporting/nice_region_error/util.rs | 6 +++--- compiler/rustc_middle/src/ty/visit.rs | 18 ++++++++++-------- src/librustdoc/clean/auto_trait.rs | 17 ++++++++--------- 6 files changed, 26 insertions(+), 25 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/astconv/bounds.rs b/compiler/rustc_hir_analysis/src/astconv/bounds.rs index 6940b4a5045..6d8a5bc0e90 100644 --- a/compiler/rustc_hir_analysis/src/astconv/bounds.rs +++ b/compiler/rustc_hir_analysis/src/astconv/bounds.rs @@ -454,9 +454,9 @@ pub(super) fn add_predicates_for_ast_type_binding( // for<'a> ::Item = &'a str // <-- 'a is bad // for<'a> >::Output = &'a str // <-- 'a is ok let late_bound_in_projection_ty = - tcx.collect_constrained_late_bound_regions(&projection_ty); + tcx.collect_constrained_late_bound_regions(projection_ty); let late_bound_in_term = - tcx.collect_referenced_late_bound_regions(&trait_ref.rebind(term)); + tcx.collect_referenced_late_bound_regions(trait_ref.rebind(term)); debug!(?late_bound_in_projection_ty); debug!(?late_bound_in_term); diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs index 296b63a8292..997392b6c4a 100644 --- a/compiler/rustc_hir_analysis/src/astconv/mod.rs +++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs @@ -2678,9 +2678,9 @@ pub fn ty_of_fn( // for<'a> fn(&'a String) -> &'a str <-- 'a is ok let inputs = bare_fn_ty.inputs(); let late_bound_in_args = - tcx.collect_constrained_late_bound_regions(&inputs.map_bound(|i| i.to_owned())); + tcx.collect_constrained_late_bound_regions(inputs.map_bound(|i| i.to_owned())); let output = bare_fn_ty.output(); - let late_bound_in_ret = tcx.collect_referenced_late_bound_regions(&output); + let late_bound_in_ret = tcx.collect_referenced_late_bound_regions(output); self.validate_late_bound_regions(late_bound_in_args, late_bound_in_ret, |br_name| { struct_span_code_err!( diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs index cffb88a1365..6a42fdb1079 100644 --- a/compiler/rustc_hir_analysis/src/collect.rs +++ b/compiler/rustc_hir_analysis/src/collect.rs @@ -520,7 +520,7 @@ fn get_new_lifetime_name<'tcx>( generics: &hir::Generics<'tcx>, ) -> String { let existing_lifetimes = tcx - .collect_referenced_late_bound_regions(&poly_trait_ref) + .collect_referenced_late_bound_regions(poly_trait_ref) .into_iter() .filter_map(|lt| { if let ty::BoundRegionKind::BrNamed(_, name) = lt { diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs index bfff00b948e..f1f8314661f 100644 --- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs +++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs @@ -5,7 +5,7 @@ use crate::infer::TyCtxt; use rustc_hir as hir; use rustc_hir::def_id::LocalDefId; -use rustc_middle::ty::{self, Binder, Region, Ty, TypeVisitable}; +use rustc_middle::ty::{self, Binder, Region, Ty, TypeFoldable}; use rustc_span::Span; /// Information about the anonymous region we are searching for. @@ -142,10 +142,10 @@ pub(super) fn is_return_type_anon( fn includes_region( &self, - ty: Binder<'tcx, impl TypeVisitable>>, + ty: Binder<'tcx, impl TypeFoldable>>, region: ty::BoundRegionKind, ) -> bool { - let late_bound_regions = self.tcx().collect_referenced_late_bound_regions(&ty); + let late_bound_regions = self.tcx().collect_referenced_late_bound_regions(ty); // We are only checking is any region meets the condition so order doesn't matter #[allow(rustc::potential_query_instability)] late_bound_regions.iter().any(|r| *r == region) diff --git a/compiler/rustc_middle/src/ty/visit.rs b/compiler/rustc_middle/src/ty/visit.rs index 1de2ceecae7..59d09c3dc78 100644 --- a/compiler/rustc_middle/src/ty/visit.rs +++ b/compiler/rustc_middle/src/ty/visit.rs @@ -2,6 +2,7 @@ use rustc_data_structures::fx::FxHashSet; use rustc_data_structures::sso::SsoHashSet; +use rustc_type_ir::fold::TypeFoldable; use std::ops::ControlFlow; pub use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor}; @@ -109,10 +110,10 @@ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow { /// variables will also be equated. pub fn collect_constrained_late_bound_regions( self, - value: &Binder<'tcx, T>, + value: Binder<'tcx, T>, ) -> FxHashSet where - T: TypeVisitable>, + T: TypeFoldable>, { self.collect_late_bound_regions(value, true) } @@ -120,25 +121,26 @@ pub fn collect_constrained_late_bound_regions( /// Returns a set of all late-bound regions that appear in `value` anywhere. pub fn collect_referenced_late_bound_regions( self, - value: &Binder<'tcx, T>, + value: Binder<'tcx, T>, ) -> FxHashSet where - T: TypeVisitable>, + T: TypeFoldable>, { self.collect_late_bound_regions(value, false) } fn collect_late_bound_regions( self, - value: &Binder<'tcx, T>, + value: Binder<'tcx, T>, just_constrained: bool, ) -> FxHashSet where - T: TypeVisitable>, + T: TypeFoldable>, { - let mut collector = LateBoundRegionsCollector::new(self, just_constrained); + let mut collector = LateBoundRegionsCollector::new(just_constrained); + let value = value.skip_binder(); let value = if just_constrained { self.expand_weak_alias_tys(value) } else { value }; - let result = value.as_ref().skip_binder().visit_with(&mut collector); + let result = value.visit_with(&mut collector); assert!(result.is_continue()); // should never have stopped early collector.regions } diff --git a/src/librustdoc/clean/auto_trait.rs b/src/librustdoc/clean/auto_trait.rs index 8cc4201c3fc..fbc2c3c5af4 100644 --- a/src/librustdoc/clean/auto_trait.rs +++ b/src/librustdoc/clean/auto_trait.rs @@ -318,15 +318,14 @@ fn handle_lifetimes<'cx>( fn extract_for_generics(&self, pred: ty::Clause<'tcx>) -> FxHashSet { let bound_predicate = pred.kind(); let tcx = self.cx.tcx; - let regions = match bound_predicate.skip_binder() { - ty::ClauseKind::Trait(poly_trait_pred) => { - tcx.collect_referenced_late_bound_regions(&bound_predicate.rebind(poly_trait_pred)) - } - ty::ClauseKind::Projection(poly_proj_pred) => { - tcx.collect_referenced_late_bound_regions(&bound_predicate.rebind(poly_proj_pred)) - } - _ => return FxHashSet::default(), - }; + let regions = + match bound_predicate.skip_binder() { + ty::ClauseKind::Trait(poly_trait_pred) => tcx + .collect_referenced_late_bound_regions(bound_predicate.rebind(poly_trait_pred)), + ty::ClauseKind::Projection(poly_proj_pred) => tcx + .collect_referenced_late_bound_regions(bound_predicate.rebind(poly_proj_pred)), + _ => return FxHashSet::default(), + }; regions .into_iter() From 1b3df6f068cb676486c511890148dbb7981b62b1 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Le=C3=B3n=20Orell=20Valerian=20Liehr?= Date: Tue, 20 Feb 2024 14:29:50 +0100 Subject: [PATCH 4/5] Use expand_weak_alias_tys when collecting constrained generics params in impls --- .../src/constrained_generic_params.rs | 53 +++++++------------ .../rustc_hir_analysis/src/impl_wf_check.rs | 2 +- .../src/impl_wf_check/min_specialization.rs | 10 ++-- 3 files changed, 25 insertions(+), 40 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs index 4ce43bb4887..b8de2e46934 100644 --- a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs +++ b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs @@ -1,8 +1,8 @@ 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; +use rustc_type_ir::fold::TypeFoldable; use std::ops::ControlFlow; #[derive(Clone, PartialEq, Eq, Hash, Debug)] @@ -33,62 +33,47 @@ pub fn parameters_for_impl<'tcx>( impl_trait_ref: Option>, ) -> FxHashSet { let vec = match impl_trait_ref { - Some(tr) => parameters_for(tcx, &tr, false), - None => parameters_for(tcx, &impl_self_ty, false), + Some(tr) => parameters_for(tcx, tr, false), + None => parameters_for(tcx, impl_self_ty, false), }; vec.into_iter().collect() } /// If `include_nonconstraining` is false, returns the list of parameters that are -/// constrained by `t` - i.e., the value of each parameter in the list is -/// uniquely determined by `t` (see RFC 447). If it is true, return the list -/// of parameters whose values are needed in order to constrain `ty` - these +/// constrained by `value` - i.e., the value of each parameter in the list is +/// uniquely determined by `value` (see RFC 447). If it is true, return the list +/// of parameters whose values are needed in order to constrain `value` - these /// differ, with the latter being a superset, in the presence of projections. pub fn parameters_for<'tcx>( tcx: TyCtxt<'tcx>, - t: &impl TypeVisitable>, + value: impl TypeFoldable>, include_nonconstraining: bool, ) -> Vec { - let mut collector = - ParameterCollector { tcx, parameters: vec![], include_nonconstraining, depth: 0 }; - t.visit_with(&mut collector); + let mut collector = ParameterCollector { parameters: vec![], include_nonconstraining }; + let value = if !include_nonconstraining { tcx.expand_weak_alias_tys(value) } else { value }; + value.visit_with(&mut collector); collector.parameters } -struct ParameterCollector<'tcx> { - tcx: TyCtxt<'tcx>, +struct ParameterCollector { parameters: Vec, include_nonconstraining: bool, - depth: usize, } -impl<'tcx> TypeVisitor> for ParameterCollector<'tcx> { +impl<'tcx> TypeVisitor> for ParameterCollector { fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow { match *t.kind() { + // Projections are not injective in general. 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 - // ` (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)); + // All weak alias types should've been expanded beforehand. + ty::Alias(ty::Weak, _) if !self.include_nonconstraining => { + bug!("unexpected weak alias type") } + ty::Param(param) => self.parameters.push(Parameter::from(param)), _ => {} } @@ -224,12 +209,12 @@ pub fn setup_constraining_predicates<'tcx>( // `<::Baz as Iterator>::Output = ::Output` // Then the projection only applies if `T` is known, but it still // does not determine `U`. - let inputs = parameters_for(tcx, &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(tcx, &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 b4cec1d9882..9d7866fe3e0 100644 --- a/compiler/rustc_hir_analysis/src/impl_wf_check.rs +++ b/compiler/rustc_hir_analysis/src/impl_wf_check.rs @@ -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, &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 bd4fce81377..be1be1a1354 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 @@ -133,7 +133,7 @@ fn check_always_applicable( res = res.and(check_constness(tcx, impl1_def_id, impl2_node, span)); res = res.and(check_static_lifetimes(tcx, &parent_args, span)); - res = res.and(check_duplicate_params(tcx, impl1_args, &parent_args, span)); + res = res.and(check_duplicate_params(tcx, impl1_args, parent_args, span)); res = res.and(check_predicates(tcx, impl1_def_id, impl1_args, impl2_node, impl2_args, span)); res @@ -266,15 +266,15 @@ fn unconstrained_parent_impl_args<'tcx>( continue; } - unconstrained_parameters.extend(cgp::parameters_for(tcx, &projection_ty, true)); + unconstrained_parameters.extend(cgp::parameters_for(tcx, projection_ty, true)); - for param in cgp::parameters_for(tcx, &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(tcx, &projected_ty, true)); + unconstrained_parameters.extend(cgp::parameters_for(tcx, projected_ty, true)); } } @@ -309,7 +309,7 @@ fn unconstrained_parent_impl_args<'tcx>( fn check_duplicate_params<'tcx>( tcx: TyCtxt<'tcx>, impl1_args: GenericArgsRef<'tcx>, - parent_args: &Vec>, + parent_args: Vec>, span: Span, ) -> Result<(), ErrorGuaranteed> { let mut base_params = cgp::parameters_for(tcx, parent_args, true); From f515f99e9149b1f9c8d247b1d0fd543b1cd1fd37 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Le=C3=B3n=20Orell=20Valerian=20Liehr?= Date: Tue, 20 Feb 2024 15:08:15 +0100 Subject: [PATCH 5/5] Move the peeling function for weak alias types --- .../src/coherence/inherent_impls.rs | 29 +--------------- compiler/rustc_middle/src/ty/util.rs | 33 +++++++++++++++++++ 2 files changed, 34 insertions(+), 28 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs b/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs index 4823472cf96..32f31201254 100644 --- a/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs +++ b/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs @@ -144,7 +144,7 @@ fn check_item(&mut self, id: hir::ItemId) -> Result<(), ErrorGuaranteed> { 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); + let self_ty = self.tcx.peel_off_weak_alias_tys(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), @@ -186,30 +186,3 @@ fn check_item(&mut self, id: hir::ItemId) -> Result<(), ErrorGuaranteed> { } } } - -/// Peel off all weak alias types in this type until there are none left. -/// -///
-/// -/// This assumes that `ty` gets normalized later and that any overflows occurring -/// during said normalization get reported. -/// -///
-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_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs index ff9d1ed6ae9..72a1905c147 100644 --- a/compiler/rustc_middle/src/ty/util.rs +++ b/compiler/rustc_middle/src/ty/util.rs @@ -892,6 +892,39 @@ pub fn with_opt_host_effect_param( pub fn expand_weak_alias_tys>>(self, value: T) -> T { value.fold_with(&mut WeakAliasTypeExpander { tcx: self, depth: 0 }) } + + /// Peel off all [weak alias types] in this type until there are none left. + /// + /// This only expands weak alias types in “head” / outermost positions. It can + /// be used over [expand_weak_alias_tys] as an optimization in situations where + /// one only really cares about the *kind* of the final aliased type but not + /// the types the other constituent types alias. + /// + ///
+ /// This delays a bug on overflow! Therefore you need to be certain that the + /// type gets fully normalized at a later stage. + ///
+ /// + /// [weak]: ty::Weak + /// [expand_weak_alias_tys]: Self::expand_weak_alias_tys + pub fn peel_off_weak_alias_tys(self, mut ty: Ty<'tcx>) -> Ty<'tcx> { + let ty::Alias(ty::Weak, _) = ty.kind() else { return ty }; + + let limit = self.recursion_limit(); + let mut depth = 0; + + while let ty::Alias(ty::Weak, alias) = ty.kind() { + if !limit.value_within_limit(depth) { + let guar = self.dcx().delayed_bug("overflow expanding weak alias type"); + return Ty::new_error(self, guar); + } + + ty = self.type_of(alias.def_id).instantiate(self, alias.args); + depth += 1; + } + + ty + } } struct OpaqueTypeExpander<'tcx> {