diff options
| -rw-r--r-- | compiler/rustc_borrowck/src/type_check/relate_tys.rs | 16 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/canonical/query_response.rs | 7 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/relate/combine.rs | 199 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/relate/equate.rs | 13 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/relate/generalize.rs | 383 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/relate/glb.rs | 5 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/relate/lub.rs | 5 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/relate/mod.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/relate/nll.rs | 233 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/relate/sub.rs | 13 | ||||
| -rw-r--r-- | tests/ui/coherence/occurs-check/associated-type.next.stderr | 8 | ||||
| -rw-r--r-- | tests/ui/coherence/occurs-check/associated-type.old.stderr | 8 | ||||
| -rw-r--r-- | tests/ui/impl-trait/rpit/early_bound.rs | 1 | ||||
| -rw-r--r-- | tests/ui/impl-trait/rpit/early_bound.stderr | 14 | ||||
| -rw-r--r-- | tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.next.stderr | 4 |
15 files changed, 345 insertions, 566 deletions
diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs index ee0bd13109b..a60175d9896 100644 --- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs +++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs @@ -143,22 +143,6 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> reg } - #[instrument(skip(self), level = "debug")] - fn generalize_existential(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> { - let reg = self.type_checker.infcx.next_nll_region_var_in_universe( - NllRegionVariableOrigin::Existential { from_forall: false }, - universe, - ); - - if cfg!(debug_assertions) { - let mut var_to_origin = self.type_checker.infcx.reg_var_to_origin.borrow_mut(); - let prev = var_to_origin.insert(reg.as_var(), RegionCtxt::Existential(None)); - assert_eq!(prev, None); - } - - reg - } - fn push_outlives( &mut self, sup: ty::Region<'tcx>, diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs index 56a45586c9d..4539ebf8754 100644 --- a/compiler/rustc_infer/src/infer/canonical/query_response.rs +++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs @@ -731,13 +731,6 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> { ty::Region::new_placeholder(self.infcx.tcx, placeholder) } - fn generalize_existential(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> { - self.infcx.next_nll_region_var_in_universe( - NllRegionVariableOrigin::Existential { from_forall: false }, - universe, - ) - } - fn push_outlives( &mut self, sup: ty::Region<'tcx>, diff --git a/compiler/rustc_infer/src/infer/relate/combine.rs b/compiler/rustc_infer/src/infer/relate/combine.rs index 7edfbf02a68..454de4f9785 100644 --- a/compiler/rustc_infer/src/infer/relate/combine.rs +++ b/compiler/rustc_infer/src/infer/relate/combine.rs @@ -23,19 +23,18 @@ //! this should be correctly updated. use super::equate::Equate; -use super::generalize::{self, CombineDelegate, Generalization}; use super::glb::Glb; use super::lub::Lub; use super::sub::Sub; use crate::infer::{DefineOpaqueTypes, InferCtxt, TypeTrace}; use crate::traits::{Obligation, PredicateObligations}; use rustc_middle::infer::canonical::OriginalQueryValues; -use rustc_middle::infer::unify_key::{ConstVariableValue, EffectVarValue}; +use rustc_middle::infer::unify_key::EffectVarValue; use rustc_middle::ty::error::{ExpectedFound, TypeError}; use rustc_middle::ty::relate::{RelateResult, TypeRelation}; use rustc_middle::ty::{self, InferConst, ToPredicate, Ty, TyCtxt, TypeVisitableExt}; -use rustc_middle::ty::{AliasRelationDirection, TyVar}; use rustc_middle::ty::{IntType, UintType}; +use rustc_span::Span; #[derive(Clone)] pub struct CombineFields<'infcx, 'tcx> { @@ -221,11 +220,11 @@ impl<'tcx> InferCtxt<'tcx> { } (ty::ConstKind::Infer(InferConst::Var(vid)), _) => { - return self.unify_const_variable(vid, b); + return self.instantiate_const_var(vid, b); } (_, ty::ConstKind::Infer(InferConst::Var(vid))) => { - return self.unify_const_variable(vid, a); + return self.instantiate_const_var(vid, a); } (ty::ConstKind::Infer(InferConst::EffectVar(vid)), _) => { @@ -259,69 +258,6 @@ impl<'tcx> InferCtxt<'tcx> { ty::relate::structurally_relate_consts(relation, a, b) } - /// Unifies the const variable `target_vid` with the given constant. - /// - /// This also tests if the given const `ct` contains an inference variable which was previously - /// unioned with `target_vid`. If this is the case, inferring `target_vid` to `ct` - /// would result in an infinite type as we continuously replace an inference variable - /// in `ct` with `ct` itself. - /// - /// This is especially important as unevaluated consts use their parents generics. - /// They therefore often contain unused args, making these errors far more likely. - /// - /// A good example of this is the following: - /// - /// ```compile_fail,E0308 - /// #![feature(generic_const_exprs)] - /// - /// fn bind<const N: usize>(value: [u8; N]) -> [u8; 3 + 4] { - /// todo!() - /// } - /// - /// fn main() { - /// let mut arr = Default::default(); - /// arr = bind(arr); - /// } - /// ``` - /// - /// Here `3 + 4` ends up as `ConstKind::Unevaluated` which uses the generics - /// of `fn bind` (meaning that its args contain `N`). - /// - /// `bind(arr)` now infers that the type of `arr` must be `[u8; N]`. - /// The assignment `arr = bind(arr)` now tries to equate `N` with `3 + 4`. - /// - /// As `3 + 4` contains `N` in its args, this must not succeed. - /// - /// See `tests/ui/const-generics/occurs-check/` for more examples where this is relevant. - #[instrument(level = "debug", skip(self))] - fn unify_const_variable( - &self, - target_vid: ty::ConstVid, - ct: ty::Const<'tcx>, - ) -> RelateResult<'tcx, ty::Const<'tcx>> { - let span = match self.inner.borrow_mut().const_unification_table().probe_value(target_vid) { - ConstVariableValue::Known { value } => { - bug!("instantiating a known const var: {target_vid:?} {value} {ct}") - } - ConstVariableValue::Unknown { origin, universe: _ } => origin.span, - }; - // FIXME(generic_const_exprs): Occurs check failures for unevaluated - // constants and generic expressions are not yet handled correctly. - let Generalization { value_may_be_infer: value, needs_wf: _ } = generalize::generalize( - self, - &mut CombineDelegate { infcx: self, span }, - ct, - target_vid, - ty::Variance::Invariant, - )?; - - self.inner - .borrow_mut() - .const_unification_table() - .union_value(target_vid, ConstVariableValue::Known { value }); - Ok(value) - } - fn unify_integral_variable( &self, vid_is_expected: bool, @@ -383,131 +319,6 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> { Glb::new(self, a_is_expected) } - /// Here, `dir` is either `EqTo`, `SubtypeOf`, or `SupertypeOf`. - /// The idea is that we should ensure that the type `a_ty` is equal - /// to, a subtype of, or a supertype of (respectively) the type - /// to which `b_vid` is bound. - /// - /// Since `b_vid` has not yet been instantiated with a type, we - /// will first instantiate `b_vid` with a *generalized* version - /// of `a_ty`. Generalization introduces other inference - /// variables wherever subtyping could occur. - #[instrument(skip(self), level = "debug")] - pub fn instantiate( - &mut self, - a_ty: Ty<'tcx>, - ambient_variance: ty::Variance, - b_vid: ty::TyVid, - a_is_expected: bool, - ) -> RelateResult<'tcx, ()> { - // Get the actual variable that b_vid has been inferred to - debug_assert!(self.infcx.inner.borrow_mut().type_variables().probe(b_vid).is_unknown()); - - // Generalize type of `a_ty` appropriately depending on the - // direction. As an example, assume: - // - // - `a_ty == &'x ?1`, where `'x` is some free region and `?1` is an - // inference variable, - // - and `dir` == `SubtypeOf`. - // - // Then the generalized form `b_ty` would be `&'?2 ?3`, where - // `'?2` and `?3` are fresh region/type inference - // variables. (Down below, we will relate `a_ty <: b_ty`, - // adding constraints like `'x: '?2` and `?1 <: ?3`.) - let Generalization { value_may_be_infer: b_ty, needs_wf } = generalize::generalize( - self.infcx, - &mut CombineDelegate { infcx: self.infcx, span: self.trace.span() }, - a_ty, - b_vid, - ambient_variance, - )?; - - // Constrain `b_vid` to the generalized type `b_ty`. - if let &ty::Infer(TyVar(b_ty_vid)) = b_ty.kind() { - self.infcx.inner.borrow_mut().type_variables().equate(b_vid, b_ty_vid); - } else { - self.infcx.inner.borrow_mut().type_variables().instantiate(b_vid, b_ty); - } - - if needs_wf { - self.obligations.push(Obligation::new( - self.tcx(), - self.trace.cause.clone(), - self.param_env, - ty::Binder::dummy(ty::PredicateKind::Clause(ty::ClauseKind::WellFormed( - b_ty.into(), - ))), - )); - } - - // Finally, relate `b_ty` to `a_ty`, as described in previous comment. - // - // FIXME(#16847): This code is non-ideal because all these subtype - // relations wind up attributed to the same spans. We need - // to associate causes/spans with each of the relations in - // the stack to get this right. - if b_ty.is_ty_var() { - // This happens for cases like `<?0 as Trait>::Assoc == ?0`. - // We can't instantiate `?0` here as that would result in a - // cyclic type. We instead delay the unification in case - // the alias can be normalized to something which does not - // mention `?0`. - if self.infcx.next_trait_solver() { - let (lhs, rhs, direction) = match ambient_variance { - ty::Variance::Invariant => { - (a_ty.into(), b_ty.into(), AliasRelationDirection::Equate) - } - ty::Variance::Covariant => { - (a_ty.into(), b_ty.into(), AliasRelationDirection::Subtype) - } - ty::Variance::Contravariant => { - (b_ty.into(), a_ty.into(), AliasRelationDirection::Subtype) - } - ty::Variance::Bivariant => unreachable!("bivariant generalization"), - }; - self.obligations.push(Obligation::new( - self.tcx(), - self.trace.cause.clone(), - self.param_env, - ty::PredicateKind::AliasRelate(lhs, rhs, direction), - )); - } else { - match a_ty.kind() { - &ty::Alias(ty::Projection, data) => { - // FIXME: This does not handle subtyping correctly, we could - // instead create a new inference variable for `a_ty`, emitting - // `Projection(a_ty, a_infer)` and `a_infer <: b_ty`. - self.obligations.push(Obligation::new( - self.tcx(), - self.trace.cause.clone(), - self.param_env, - ty::ProjectionPredicate { projection_ty: data, term: b_ty.into() }, - )) - } - // The old solver only accepts projection predicates for associated types. - ty::Alias(ty::Inherent | ty::Weak | ty::Opaque, _) => { - return Err(TypeError::CyclicTy(a_ty)); - } - _ => bug!("generalizated `{a_ty:?} to infer, not an alias"), - } - } - } else { - match ambient_variance { - ty::Variance::Invariant => self.equate(a_is_expected).relate(a_ty, b_ty), - ty::Variance::Covariant => self.sub(a_is_expected).relate(a_ty, b_ty), - ty::Variance::Contravariant => self.sub(a_is_expected).relate_with_variance( - ty::Contravariant, - ty::VarianceDiagInfo::default(), - a_ty, - b_ty, - ), - ty::Variance::Bivariant => unreachable!("bivariant generalization"), - }?; - } - - Ok(()) - } - pub fn register_obligations(&mut self, obligations: PredicateObligations<'tcx>) { self.obligations.extend(obligations); } @@ -520,6 +331,8 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> { } pub trait ObligationEmittingRelation<'tcx>: TypeRelation<'tcx> { + fn span(&self) -> Span; + fn param_env(&self) -> ty::ParamEnv<'tcx>; /// Register obligations that must hold in order for this relation to hold diff --git a/compiler/rustc_infer/src/infer/relate/equate.rs b/compiler/rustc_infer/src/infer/relate/equate.rs index cb62f258373..0087add4c72 100644 --- a/compiler/rustc_infer/src/infer/relate/equate.rs +++ b/compiler/rustc_infer/src/infer/relate/equate.rs @@ -8,6 +8,7 @@ use rustc_middle::ty::TyVar; use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt}; use rustc_hir::def_id::DefId; +use rustc_span::Span; /// Ensures `a` is made equal to `b`. Returns `a` on success. pub struct Equate<'combine, 'infcx, 'tcx> { @@ -81,12 +82,12 @@ impl<'tcx> TypeRelation<'tcx> for Equate<'_, '_, 'tcx> { infcx.inner.borrow_mut().type_variables().equate(a_id, b_id); } - (&ty::Infer(TyVar(a_id)), _) => { - self.fields.instantiate(b, ty::Invariant, a_id, self.a_is_expected)?; + (&ty::Infer(TyVar(a_vid)), _) => { + infcx.instantiate_ty_var(self, self.a_is_expected, a_vid, ty::Invariant, b)?; } - (_, &ty::Infer(TyVar(b_id))) => { - self.fields.instantiate(a, ty::Invariant, b_id, self.a_is_expected)?; + (_, &ty::Infer(TyVar(b_vid))) => { + infcx.instantiate_ty_var(self, !self.a_is_expected, b_vid, ty::Invariant, a)?; } ( @@ -170,6 +171,10 @@ impl<'tcx> TypeRelation<'tcx> for Equate<'_, '_, 'tcx> { } impl<'tcx> ObligationEmittingRelation<'tcx> for Equate<'_, '_, 'tcx> { + fn span(&self) -> Span { + self.fields.trace.span() + } + fn param_env(&self) -> ty::ParamEnv<'tcx> { self.fields.param_env } diff --git a/compiler/rustc_infer/src/infer/relate/generalize.rs b/compiler/rustc_infer/src/infer/relate/generalize.rs index bc16d613ccb..c0cb02916fe 100644 --- a/compiler/rustc_infer/src/infer/relate/generalize.rs +++ b/compiler/rustc_infer/src/infer/relate/generalize.rs @@ -1,5 +1,7 @@ use std::mem; +use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind, TypeVariableValue}; +use crate::infer::{InferCtxt, ObligationEmittingRelation, RegionVariableOrigin}; use rustc_data_structures::sso::SsoHashMap; use rustc_data_structures::stack::ensure_sufficient_stack; use rustc_hir::def_id::DefId; @@ -7,98 +9,225 @@ use rustc_middle::infer::unify_key::ConstVariableValue; use rustc_middle::ty::error::TypeError; use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation}; use rustc_middle::ty::visit::MaxUniverse; -use rustc_middle::ty::{self, InferConst, Term, Ty, TyCtxt, TypeVisitable, TypeVisitableExt}; +use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_middle::ty::{AliasRelationDirection, InferConst, Term, TypeVisitable, TypeVisitableExt}; use rustc_span::Span; -use crate::infer::nll_relate::TypeRelatingDelegate; -use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind, TypeVariableValue}; -use crate::infer::{InferCtxt, RegionVariableOrigin}; - -/// Attempts to generalize `term` for the type variable `for_vid`. -/// This checks for cycles -- that is, whether the type `term` -/// references `for_vid`. -pub fn generalize<'tcx, D: GeneralizerDelegate<'tcx>, T: Into<Term<'tcx>> + Relate<'tcx>>( - infcx: &InferCtxt<'tcx>, - delegate: &mut D, - term: T, - for_vid: impl Into<ty::TermVid>, - ambient_variance: ty::Variance, -) -> RelateResult<'tcx, Generalization<T>> { - let (for_universe, root_vid) = match for_vid.into() { - ty::TermVid::Ty(ty_vid) => ( - infcx.probe_ty_var(ty_vid).unwrap_err(), - ty::TermVid::Ty(infcx.inner.borrow_mut().type_variables().sub_root_var(ty_vid)), - ), - ty::TermVid::Const(ct_vid) => ( - infcx.probe_const_var(ct_vid).unwrap_err(), - ty::TermVid::Const(infcx.inner.borrow_mut().const_unification_table().find(ct_vid).vid), - ), - }; - - let mut generalizer = Generalizer { - infcx, - delegate, - ambient_variance, - root_vid, - for_universe, - root_term: term.into(), - in_alias: false, - needs_wf: false, - cache: Default::default(), - }; - - assert!(!term.has_escaping_bound_vars()); - let value_may_be_infer = generalizer.relate(term, term)?; - let needs_wf = generalizer.needs_wf; - Ok(Generalization { value_may_be_infer, needs_wf }) -} - -/// Abstracts the handling of region vars between HIR and MIR/NLL typechecking -/// in the generalizer code. -pub trait GeneralizerDelegate<'tcx> { - fn forbid_inference_vars() -> bool; - - fn span(&self) -> Span; +impl<'tcx> InferCtxt<'tcx> { + /// The idea is that we should ensure that the type variable `target_vid` + /// is equal to, a subtype of, or a supertype of `source_ty`. + /// + /// For this, we will instantiate `target_vid` with a *generalized* version + /// of `source_ty`. Generalization introduces other inference variables wherever + /// subtyping could occur. This also does the occurs checks, detecting whether + /// instantiating `target_vid` would result in a cyclic type. We eagerly error + /// in this case. + #[instrument(skip(self, relation, target_is_expected), level = "debug")] + pub(super) fn instantiate_ty_var<R: ObligationEmittingRelation<'tcx>>( + &self, + relation: &mut R, + target_is_expected: bool, + target_vid: ty::TyVid, + ambient_variance: ty::Variance, + source_ty: Ty<'tcx>, + ) -> RelateResult<'tcx, ()> { + debug_assert!(self.inner.borrow_mut().type_variables().probe(target_vid).is_unknown()); + + // Generalize `source_ty` depending on the current variance. As an example, assume + // `?target <: &'x ?1`, where `'x` is some free region and `?1` is an inference + // variable. + // + // Then the `generalized_ty` would be `&'?2 ?3`, where `'?2` and `?3` are fresh + // region/type inference variables. + // + // We then relate `generalized_ty <: source_ty`,adding constraints like `'x: '?2` and `?1 <: ?3`. + let Generalization { value_may_be_infer: generalized_ty, has_unconstrained_ty_var } = + self.generalize(relation.span(), target_vid, ambient_variance, source_ty)?; + + // Constrain `b_vid` to the generalized type `generalized_ty`. + if let &ty::Infer(ty::TyVar(generalized_vid)) = generalized_ty.kind() { + self.inner.borrow_mut().type_variables().equate(target_vid, generalized_vid); + } else { + self.inner.borrow_mut().type_variables().instantiate(target_vid, generalized_ty); + } - fn generalize_region(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx>; -} + // See the comment on `Generalization::has_unconstrained_ty_var`. + if has_unconstrained_ty_var { + relation.register_predicates([ty::ClauseKind::WellFormed(generalized_ty.into())]); + } -pub struct CombineDelegate<'cx, 'tcx> { - pub infcx: &'cx InferCtxt<'tcx>, - pub span: Span, -} + // Finally, relate `generalized_ty` to `source_ty`, as described in previous comment. + // + // FIXME(#16847): This code is non-ideal because all these subtype + // relations wind up attributed to the same spans. We need + // to associate causes/spans with each of the relations in + // the stack to get this right. + if generalized_ty.is_ty_var() { + // This happens for cases like `<?0 as Trait>::Assoc == ?0`. + // We can't instantiate `?0` here as that would result in a + // cyclic type. We instead delay the unification in case + // the alias can be normalized to something which does not + // mention `?0`. + if self.next_trait_solver() { + let (lhs, rhs, direction) = match ambient_variance { + ty::Variance::Invariant => { + (generalized_ty.into(), source_ty.into(), AliasRelationDirection::Equate) + } + ty::Variance::Covariant => { + (generalized_ty.into(), source_ty.into(), AliasRelationDirection::Subtype) + } + ty::Variance::Contravariant => { + (source_ty.into(), generalized_ty.into(), AliasRelationDirection::Subtype) + } + ty::Variance::Bivariant => unreachable!("bivariant generalization"), + }; -impl<'tcx> GeneralizerDelegate<'tcx> for CombineDelegate<'_, 'tcx> { - fn forbid_inference_vars() -> bool { - false - } + relation.register_predicates([ty::PredicateKind::AliasRelate(lhs, rhs, direction)]); + } else { + match source_ty.kind() { + &ty::Alias(ty::Projection, data) => { + // FIXME: This does not handle subtyping correctly, we could + // instead create a new inference variable `?normalized_source`, emitting + // `Projection(normalized_source, ?ty_normalized)` and `?normalized_source <: generalized_ty`. + relation.register_predicates([ty::ProjectionPredicate { + projection_ty: data, + term: generalized_ty.into(), + }]); + } + // The old solver only accepts projection predicates for associated types. + ty::Alias(ty::Inherent | ty::Weak | ty::Opaque, _) => { + return Err(TypeError::CyclicTy(source_ty)); + } + _ => bug!("generalized `{source_ty:?} to infer, not an alias"), + } + } + } else { + // HACK: make sure that we `a_is_expected` continues to be + // correct when relating the generalized type with the source. + if target_is_expected == relation.a_is_expected() { + relation.relate_with_variance( + ambient_variance, + ty::VarianceDiagInfo::default(), + generalized_ty, + source_ty, + )?; + } else { + relation.relate_with_variance( + ambient_variance.xform(ty::Contravariant), + ty::VarianceDiagInfo::default(), + source_ty, + generalized_ty, + )?; + } + } - fn span(&self) -> Span { - self.span + Ok(()) } - fn generalize_region(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> { - // FIXME: This is non-ideal because we don't give a - // very descriptive origin for this region variable. - self.infcx - .next_region_var_in_universe(RegionVariableOrigin::MiscVariable(self.span), universe) - } -} + /// Instantiates the const variable `target_vid` with the given constant. + /// + /// This also tests if the given const `ct` contains an inference variable which was previously + /// unioned with `target_vid`. If this is the case, inferring `target_vid` to `ct` + /// would result in an infinite type as we continuously replace an inference variable + /// in `ct` with `ct` itself. + /// + /// This is especially important as unevaluated consts use their parents generics. + /// They therefore often contain unused args, making these errors far more likely. + /// + /// A good example of this is the following: + /// + /// ```compile_fail,E0308 + /// #![feature(generic_const_exprs)] + /// + /// fn bind<const N: usize>(value: [u8; N]) -> [u8; 3 + 4] { + /// todo!() + /// } + /// + /// fn main() { + /// let mut arr = Default::default(); + /// arr = bind(arr); + /// } + /// ``` + /// + /// Here `3 + 4` ends up as `ConstKind::Unevaluated` which uses the generics + /// of `fn bind` (meaning that its args contain `N`). + /// + /// `bind(arr)` now infers that the type of `arr` must be `[u8; N]`. + /// The assignment `arr = bind(arr)` now tries to equate `N` with `3 + 4`. + /// + /// As `3 + 4` contains `N` in its args, this must not succeed. + /// + /// See `tests/ui/const-generics/occurs-check/` for more examples where this is relevant. + #[instrument(level = "debug", skip(self))] + pub(super) fn instantiate_const_var( + &self, + target_vid: ty::ConstVid, + source_ct: ty::Const<'tcx>, + ) -> RelateResult<'tcx, ty::Const<'tcx>> { + let span = match self.inner.borrow_mut().const_unification_table().probe_value(target_vid) { + ConstVariableValue::Known { value } => { + bug!("instantiating a known const var: {target_vid:?} {value} {source_ct}") + } + ConstVariableValue::Unknown { origin, universe: _ } => origin.span, + }; + // FIXME(generic_const_exprs): Occurs check failures for unevaluated + // constants and generic expressions are not yet handled correctly. + let Generalization { value_may_be_infer: generalized_ct, has_unconstrained_ty_var } = + self.generalize(span, target_vid, ty::Variance::Invariant, source_ct)?; + + debug_assert!(!generalized_ct.is_ct_infer()); + if has_unconstrained_ty_var { + span_bug!(span, "unconstrained ty var when generalizing `{source_ct:?}`"); + } -impl<'tcx, T> GeneralizerDelegate<'tcx> for T -where - T: TypeRelatingDelegate<'tcx>, -{ - fn forbid_inference_vars() -> bool { - <Self as TypeRelatingDelegate<'tcx>>::forbid_inference_vars() - } + self.inner + .borrow_mut() + .const_unification_table() + .union_value(target_vid, ConstVariableValue::Known { value: generalized_ct }); - fn span(&self) -> Span { - <Self as TypeRelatingDelegate<'tcx>>::span(&self) + // FIXME(generic_const_exprs): We have to make sure we actually equate + // `generalized_ct` and `source_ct` here. + Ok(generalized_ct) } - fn generalize_region(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> { - <Self as TypeRelatingDelegate<'tcx>>::generalize_existential(self, universe) + /// Attempts to generalize `source_term` for the type variable `target_vid`. + /// This checks for cycles -- that is, whether `source_term` references `target_vid`. + fn generalize<T: Into<Term<'tcx>> + Relate<'tcx>>( + &self, + span: Span, + target_vid: impl Into<ty::TermVid>, + ambient_variance: ty::Variance, + source_term: T, + ) -> RelateResult<'tcx, Generalization<T>> { + assert!(!source_term.has_escaping_bound_vars()); + let (for_universe, root_vid) = match target_vid.into() { + ty::TermVid::Ty(ty_vid) => ( + self.probe_ty_var(ty_vid).unwrap_err(), + ty::TermVid::Ty(self.inner.borrow_mut().type_variables().sub_root_var(ty_vid)), + ), + ty::TermVid::Const(ct_vid) => ( + self.probe_const_var(ct_vid).unwrap_err(), + ty::TermVid::Const( + self.inner.borrow_mut().const_unification_table().find(ct_vid).vid, + ), + ), + }; + + let mut generalizer = Generalizer { + infcx: self, + span, + root_vid, + for_universe, + ambient_variance, + root_term: source_term.into(), + in_alias: false, + has_unconstrained_ty_var: false, + cache: Default::default(), + }; + + let value_may_be_infer = generalizer.relate(source_term, source_term)?; + let has_unconstrained_ty_var = generalizer.has_unconstrained_ty_var; + Ok(Generalization { value_may_be_infer, has_unconstrained_ty_var }) } } @@ -115,18 +244,10 @@ where /// establishes `'0: 'x` as a constraint. /// /// [blog post]: https://is.gd/0hKvIr -struct Generalizer<'me, 'tcx, D> { +struct Generalizer<'me, 'tcx> { infcx: &'me InferCtxt<'tcx>, - /// This is used to abstract the behaviors of the three previous - /// generalizer-like implementations (`Generalizer`, `TypeGeneralizer`, - /// and `ConstInferUnifier`). See [`GeneralizerDelegate`] for more - /// information. - delegate: &'me mut D, - - /// After we generalize this type, we are going to relate it to - /// some other type. What will be the variance at this point? - ambient_variance: ty::Variance, + span: Span, /// The vid of the type variable that is in the process of being /// instantiated. If we find this within the value we are folding, @@ -138,6 +259,10 @@ struct Generalizer<'me, 'tcx, D> { /// we reject the relation. for_universe: ty::UniverseIndex, + /// After we generalize this type, we are going to relate it to + /// some other type. What will be the variance at this point? + ambient_variance: ty::Variance, + /// The root term (const or type) we're generalizing. Used for cycle errors. root_term: Term<'tcx>, @@ -150,11 +275,11 @@ struct Generalizer<'me, 'tcx, D> { /// hold by either normalizing the outer or the inner associated type. in_alias: bool, - /// See the field `needs_wf` in `Generalization`. - needs_wf: bool, + /// See the field `has_unconstrained_ty_var` in `Generalization`. + has_unconstrained_ty_var: bool, } -impl<'tcx, D> Generalizer<'_, 'tcx, D> { +impl<'tcx> Generalizer<'_, 'tcx> { /// Create an error that corresponds to the term kind in `root_term` fn cyclic_term_error(&self) -> TypeError<'tcx> { match self.root_term.unpack() { @@ -164,10 +289,7 @@ impl<'tcx, D> Generalizer<'_, 'tcx, D> { } } -impl<'tcx, D> TypeRelation<'tcx> for Generalizer<'_, 'tcx, D> -where - D: GeneralizerDelegate<'tcx>, -{ +impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> { fn tcx(&self) -> TyCtxt<'tcx> { self.infcx.tcx } @@ -236,12 +358,6 @@ where // subtyping. This is basically our "occurs check", preventing // us from creating infinitely sized types. let g = match *t.kind() { - ty::Infer(ty::TyVar(_)) | ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) - if D::forbid_inference_vars() => - { - bug!("unexpected inference variable encountered in NLL generalization: {t}"); - } - ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => { bug!("unexpected infer type: {t}") } @@ -272,11 +388,10 @@ where } } - // Bivariant: make a fresh var, but we - // may need a WF predicate. See - // comment on `needs_wf` field for - // more info. - ty::Bivariant => self.needs_wf = true, + // Bivariant: make a fresh var, but remember that + // it is unconstrained. See the comment in + // `Generalization`. + ty::Bivariant => self.has_unconstrained_ty_var = true, // Co/contravariant: this will be // sufficiently constrained later on. @@ -345,7 +460,7 @@ where Ok(self.infcx.next_ty_var_in_universe( TypeVariableOrigin { kind: TypeVariableOriginKind::MiscVariable, - span: self.delegate.span(), + span: self.span, }, self.for_universe, )) @@ -403,7 +518,10 @@ where } } - Ok(self.delegate.generalize_region(self.for_universe)) + Ok(self.infcx.next_region_var_in_universe( + RegionVariableOrigin::MiscVariable(self.span), + self.for_universe, + )) } #[instrument(level = "debug", skip(self, c2), ret)] @@ -415,9 +533,6 @@ where assert_eq!(c, c2); // we are misusing TypeRelation here; both LHS and RHS ought to be == match c.kind() { - ty::ConstKind::Infer(InferConst::Var(_)) if D::forbid_inference_vars() => { - bug!("unexpected inference variable encountered in NLL generalization: {:?}", c); - } ty::ConstKind::Infer(InferConst::Var(vid)) => { // If root const vids are equal, then `root_vid` and // `vid` are related and we'd be inferring an infinitely @@ -452,6 +567,9 @@ where } } ty::ConstKind::Infer(InferConst::EffectVar(_)) => Ok(c), + // FIXME: Unevaluated constants are also not rigid, so the current + // approach of always relating them structurally is incomplete. + // // FIXME: remove this branch once `structurally_relate_consts` is fully // structural. ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, args }) => { @@ -511,30 +629,27 @@ pub struct Generalization<T> { /// recursion. pub value_may_be_infer: T, - /// If true, then the generalized type may not be well-formed, - /// even if the source type is well-formed, so we should add an - /// additional check to enforce that it is. This arises in - /// particular around 'bivariant' type parameters that are only - /// constrained by a where-clause. As an example, imagine a type: + /// In general, we do not check whether all types which occur during + /// type checking are well-formed. We only check wf of user-provided types + /// and when actually using a type, e.g. for method calls. + /// + /// This means that when subtyping, we may end up with unconstrained + /// inference variables if a generalized type has bivariant parameters. + /// A parameter may only be bivariant if it is constrained by a projection + /// bound in a where-clause. As an example, imagine a type: /// /// struct Foo<A, B> where A: Iterator<Item = B> { /// data: A /// } /// - /// here, `A` will be covariant, but `B` is - /// unconstrained. However, whatever it is, for `Foo` to be WF, it - /// must be equal to `A::Item`. If we have an input `Foo<?A, ?B>`, - /// then after generalization we will wind up with a type like - /// `Foo<?C, ?D>`. When we enforce that `Foo<?A, ?B> <: Foo<?C, - /// ?D>` (or `>:`), we will wind up with the requirement that `?A - /// <: ?C`, but no particular relationship between `?B` and `?D` - /// (after all, we do not know the variance of the normalized form - /// of `A::Item` with respect to `A`). If we do nothing else, this - /// may mean that `?D` goes unconstrained (as in #41677). So, in - /// this scenario where we create a new type variable in a - /// bivariant context, we set the `needs_wf` flag to true. This - /// will force the calling code to check that `WF(Foo<?C, ?D>)` - /// holds, which in turn implies that `?C::Item == ?D`. So once - /// `?C` is constrained, that should suffice to restrict `?D`. - pub needs_wf: bool, + /// here, `A` will be covariant, but `B` is unconstrained. + /// + /// However, whatever it is, for `Foo` to be WF, it must be equal to `A::Item`. + /// If we have an input `Foo<?A, ?B>`, then after generalization we will wind + /// up with a type like `Foo<?C, ?D>`. When we enforce `Foo<?A, ?B> <: Foo<?C, ?D>`, + /// we will wind up with the requirement that `?A <: ?C`, but no particular + /// relationship between `?B` and `?D` (after all, these types may be completely + /// different). If we do nothing else, this may mean that `?D` goes unconstrained + /// (as in #41677). To avoid this we emit a `WellFormed` obligation in these cases. + pub has_unconstrained_ty_var: bool, } diff --git a/compiler/rustc_infer/src/infer/relate/glb.rs b/compiler/rustc_infer/src/infer/relate/glb.rs index aa89124301e..6cf51354599 100644 --- a/compiler/rustc_infer/src/infer/relate/glb.rs +++ b/compiler/rustc_infer/src/infer/relate/glb.rs @@ -2,6 +2,7 @@ use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation}; use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt}; +use rustc_span::Span; use super::combine::{CombineFields, ObligationEmittingRelation}; use super::lattice::{self, LatticeDir}; @@ -134,6 +135,10 @@ impl<'combine, 'infcx, 'tcx> LatticeDir<'infcx, 'tcx> for Glb<'combine, 'infcx, } impl<'tcx> ObligationEmittingRelation<'tcx> for Glb<'_, '_, 'tcx> { + fn span(&self) -> Span { + self.fields.trace.span() + } + fn param_env(&self) -> ty::ParamEnv<'tcx> { self.fields.param_env } diff --git a/compiler/rustc_infer/src/infer/relate/lub.rs b/compiler/rustc_infer/src/infer/relate/lub.rs index 87d777530c8..5b4f80fd73a 100644 --- a/compiler/rustc_infer/src/infer/relate/lub.rs +++ b/compiler/rustc_infer/src/infer/relate/lub.rs @@ -7,6 +7,7 @@ use crate::traits::{ObligationCause, PredicateObligations}; use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation}; use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt}; +use rustc_span::Span; /// "Least upper bound" (common supertype) pub struct Lub<'combine, 'infcx, 'tcx> { @@ -134,6 +135,10 @@ impl<'combine, 'infcx, 'tcx> LatticeDir<'infcx, 'tcx> for Lub<'combine, 'infcx, } impl<'tcx> ObligationEmittingRelation<'tcx> for Lub<'_, '_, 'tcx> { + fn span(&self) -> Span { + self.fields.trace.span() + } + fn param_env(&self) -> ty::ParamEnv<'tcx> { self.fields.param_env } diff --git a/compiler/rustc_infer/src/infer/relate/mod.rs b/compiler/rustc_infer/src/infer/relate/mod.rs index f688c2b74a6..26270c77f1a 100644 --- a/compiler/rustc_infer/src/infer/relate/mod.rs +++ b/compiler/rustc_infer/src/infer/relate/mod.rs @@ -3,7 +3,7 @@ pub(super) mod combine; mod equate; -pub(super) mod generalize; +mod generalize; mod glb; mod higher_ranked; mod lattice; diff --git a/compiler/rustc_infer/src/infer/relate/nll.rs b/compiler/rustc_infer/src/infer/relate/nll.rs index 5e2d2af9b85..4ba4bd38e9f 100644 --- a/compiler/rustc_infer/src/infer/relate/nll.rs +++ b/compiler/rustc_infer/src/infer/relate/nll.rs @@ -25,13 +25,11 @@ use rustc_data_structures::fx::FxHashMap; use rustc_middle::traits::ObligationCause; use rustc_middle::ty::fold::FnMutDelegate; use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation}; -use rustc_middle::ty::visit::TypeVisitableExt; +use rustc_middle::ty::TypeVisitableExt; use rustc_middle::ty::{self, InferConst, Ty, TyCtxt}; use rustc_span::{Span, Symbol}; -use std::fmt::Debug; use super::combine::ObligationEmittingRelation; -use super::generalize::{self, Generalization}; use crate::infer::InferCtxt; use crate::infer::{TypeVariableOrigin, TypeVariableOriginKind}; use crate::traits::{Obligation, PredicateObligations}; @@ -99,15 +97,6 @@ pub trait TypeRelatingDelegate<'tcx> { /// placeholder region. fn next_placeholder_region(&mut self, placeholder: ty::PlaceholderRegion) -> ty::Region<'tcx>; - /// Creates a new existential region in the given universe. This - /// is used when handling subtyping and type variables -- if we - /// have that `?X <: Foo<'a>`, for example, we would instantiate - /// `?X` with a type like `Foo<'?0>` where `'?0` is a fresh - /// existential variable created by this function. We would then - /// relate `Foo<'?0>` with `Foo<'a>` (and probably add an outlives - /// relation stating that `'?0: 'a`). - fn generalize_existential(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx>; - /// Enables some optimizations if we do not expect inference variables /// in the RHS of the relation. fn forbid_inference_vars() -> bool; @@ -153,112 +142,44 @@ where self.delegate.push_outlives(sup, sub, info); } - /// Relate a type inference variable with a value type. This works - /// by creating a "generalization" G of the value where all the - /// lifetimes are replaced with fresh inference values. This - /// generalization G becomes the value of the inference variable, - /// and is then related in turn to the value. So e.g. if you had - /// `vid = ?0` and `value = &'a u32`, we might first instantiate - /// `?0` to a type like `&'0 u32` where `'0` is a fresh variable, - /// and then relate `&'0 u32` with `&'a u32` (resulting in - /// relations between `'0` and `'a`). - /// - /// The variable `pair` can be either a `(vid, ty)` or `(ty, vid)` - /// -- in other words, it is always an (unresolved) inference - /// variable `vid` and a type `ty` that are being related, but the - /// vid may appear either as the "a" type or the "b" type, - /// depending on where it appears in the tuple. The trait - /// `VidValuePair` lets us work with the vid/type while preserving - /// the "sidedness" when necessary -- the sidedness is relevant in - /// particular for the variance and set of in-scope things. - fn relate_ty_var<PAIR: VidValuePair<'tcx>>( - &mut self, - pair: PAIR, - ) -> RelateResult<'tcx, Ty<'tcx>> { - debug!("relate_ty_var({:?})", pair); - - let vid = pair.vid(); - let value_ty = pair.value_ty(); - - // FIXME(invariance) -- this logic assumes invariance, but that is wrong. - // This only presently applies to chalk integration, as NLL - // doesn't permit type variables to appear on both sides (and - // doesn't use lazy norm). - match *value_ty.kind() { - ty::Infer(ty::TyVar(value_vid)) => { - // Two type variables: just equate them. - self.infcx.inner.borrow_mut().type_variables().equate(vid, value_vid); - return Ok(value_ty); - } - - _ => (), - } - - let generalized_ty = self.generalize(value_ty, vid)?; - debug!("relate_ty_var: generalized_ty = {:?}", generalized_ty); - - if D::forbid_inference_vars() { - // In NLL, we don't have type inference variables - // floating around, so we can do this rather imprecise - // variant of the occurs-check. - assert!(!generalized_ty.has_non_region_infer()); - } - - self.infcx.inner.borrow_mut().type_variables().instantiate(vid, generalized_ty); - - // Relate the generalized kind to the original one. - let result = pair.relate_generalized_ty(self, generalized_ty); - - debug!("relate_ty_var: complete, result = {:?}", result); - result - } - - fn generalize(&mut self, ty: Ty<'tcx>, for_vid: ty::TyVid) -> RelateResult<'tcx, Ty<'tcx>> { - let Generalization { value_may_be_infer: ty, needs_wf: _ } = generalize::generalize( - self.infcx, - &mut self.delegate, - ty, - for_vid, - self.ambient_variance, - )?; - - if ty.is_ty_var() { - span_bug!(self.delegate.span(), "occurs check failure in MIR typeck"); - } - Ok(ty) - } - - fn relate_opaques(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> { + fn relate_opaques(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> { + let infcx = self.infcx; + debug_assert!(!infcx.next_trait_solver()); let (a, b) = if self.a_is_expected() { (a, b) } else { (b, a) }; - let mut generalize = |ty, ty_is_expected| { - let var = self.infcx.next_ty_var_id_in_universe( + // `handle_opaque_type` cannot handle subtyping, so to support subtyping + // we instead eagerly generalize here. This is a bit of a mess but will go + // away once we're using the new solver. + let mut enable_subtyping = |ty, ty_is_expected| { + let ty_vid = infcx.next_ty_var_id_in_universe( TypeVariableOrigin { kind: TypeVariableOriginKind::MiscVariable, span: self.delegate.span(), }, ty::UniverseIndex::ROOT, ); - if ty_is_expected { - self.relate_ty_var((ty, var)) + + let variance = if ty_is_expected { + self.ambient_variance } else { - self.relate_ty_var((var, ty)) - } + self.ambient_variance.xform(ty::Contravariant) + }; + + self.infcx.instantiate_ty_var(self, ty_is_expected, ty_vid, variance, ty)?; + Ok(infcx.resolve_vars_if_possible(Ty::new_infer(infcx.tcx, ty::TyVar(ty_vid)))) }; + let (a, b) = match (a.kind(), b.kind()) { - (&ty::Alias(ty::Opaque, ..), _) => (a, generalize(b, false)?), - (_, &ty::Alias(ty::Opaque, ..)) => (generalize(a, true)?, b), + (&ty::Alias(ty::Opaque, ..), _) => (a, enable_subtyping(b, false)?), + (_, &ty::Alias(ty::Opaque, ..)) => (enable_subtyping(a, true)?, b), _ => unreachable!( "expected at least one opaque type in `relate_opaques`, got {a} and {b}." ), }; let cause = ObligationCause::dummy_with_span(self.delegate.span()); - let obligations = self - .infcx - .handle_opaque_type(a, b, true, &cause, self.delegate.param_env())? - .obligations; + let obligations = + infcx.handle_opaque_type(a, b, true, &cause, self.delegate.param_env())?.obligations; self.delegate.register_obligations(obligations); - trace!(a = ?a.kind(), b = ?b.kind(), "opaque type instantiated"); - Ok(a) + Ok(()) } fn enter_forall<T, U>( @@ -356,76 +277,6 @@ where } } -/// When we instantiate an inference variable with a value in -/// `relate_ty_var`, we always have the pair of a `TyVid` and a `Ty`, -/// but the ordering may vary (depending on whether the inference -/// variable was found on the `a` or `b` sides). Therefore, this trait -/// allows us to factor out common code, while preserving the order -/// when needed. -trait VidValuePair<'tcx>: Debug { - /// Extract the inference variable (which could be either the - /// first or second part of the tuple). - fn vid(&self) -> ty::TyVid; - - /// Extract the value it is being related to (which will be the - /// opposite part of the tuple from the vid). - fn value_ty(&self) -> Ty<'tcx>; - - /// Given a generalized type G that should replace the vid, relate - /// G to the value, putting G on whichever side the vid would have - /// appeared. - fn relate_generalized_ty<D>( - &self, - relate: &mut TypeRelating<'_, 'tcx, D>, - generalized_ty: Ty<'tcx>, - ) -> RelateResult<'tcx, Ty<'tcx>> - where - D: TypeRelatingDelegate<'tcx>; -} - -impl<'tcx> VidValuePair<'tcx> for (ty::TyVid, Ty<'tcx>) { - fn vid(&self) -> ty::TyVid { - self.0 - } - - fn value_ty(&self) -> Ty<'tcx> { - self.1 - } - - fn relate_generalized_ty<D>( - &self, - relate: &mut TypeRelating<'_, 'tcx, D>, - generalized_ty: Ty<'tcx>, - ) -> RelateResult<'tcx, Ty<'tcx>> - where - D: TypeRelatingDelegate<'tcx>, - { - relate.relate(generalized_ty, self.value_ty()) - } -} - -// In this case, the "vid" is the "b" type. -impl<'tcx> VidValuePair<'tcx> for (Ty<'tcx>, ty::TyVid) { - fn vid(&self) -> ty::TyVid { - self.1 - } - - fn value_ty(&self) -> Ty<'tcx> { - self.0 - } - - fn relate_generalized_ty<D>( - &self, - relate: &mut TypeRelating<'_, 'tcx, D>, - generalized_ty: Ty<'tcx>, - ) -> RelateResult<'tcx, Ty<'tcx>> - where - D: TypeRelatingDelegate<'tcx>, - { - relate.relate(self.value_ty(), generalized_ty) - } -} - impl<'tcx, D> TypeRelation<'tcx> for TypeRelating<'_, 'tcx, D> where D: TypeRelatingDelegate<'tcx>, @@ -472,6 +323,8 @@ where if !D::forbid_inference_vars() { b = self.infcx.shallow_resolve(b); + } else { + assert!(!b.has_non_region_infer(), "unexpected inference var {:?}", b); } if a == b { @@ -479,22 +332,30 @@ where } match (a.kind(), b.kind()) { - (_, &ty::Infer(ty::TyVar(vid))) => { - if D::forbid_inference_vars() { - // Forbid inference variables in the RHS. - bug!("unexpected inference var {:?}", b) - } else { - self.relate_ty_var((a, vid)) + (&ty::Infer(ty::TyVar(a_vid)), &ty::Infer(ty::TyVar(b_vid))) => { + match self.ambient_variance { + ty::Invariant => infcx.inner.borrow_mut().type_variables().equate(a_vid, b_vid), + _ => unimplemented!(), } } - (&ty::Infer(ty::TyVar(vid)), _) => self.relate_ty_var((vid, b)), + (&ty::Infer(ty::TyVar(a_vid)), _) => { + infcx.instantiate_ty_var(self, true, a_vid, self.ambient_variance, b)? + } + + (_, &ty::Infer(ty::TyVar(b_vid))) => infcx.instantiate_ty_var( + self, + false, + b_vid, + self.ambient_variance.xform(ty::Contravariant), + a, + )?, ( &ty::Alias(ty::Opaque, ty::AliasTy { def_id: a_def_id, .. }), &ty::Alias(ty::Opaque, ty::AliasTy { def_id: b_def_id, .. }), ) if a_def_id == b_def_id || infcx.next_trait_solver() => { - infcx.super_combine_tys(self, a, b).or_else(|err| { + infcx.super_combine_tys(self, a, b).map(|_| ()).or_else(|err| { // This behavior is only there for the old solver, the new solver // shouldn't ever fail. Instead, it unconditionally emits an // alias-relate goal. @@ -504,22 +365,24 @@ where "failure to relate an opaque to itself should result in an error later on", ); if a_def_id.is_local() { self.relate_opaques(a, b) } else { Err(err) } - }) + })?; } (&ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }), _) | (_, &ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. })) if def_id.is_local() && !self.infcx.next_trait_solver() => { - self.relate_opaques(a, b) + self.relate_opaques(a, b)?; } _ => { debug!(?a, ?b, ?self.ambient_variance); // Will also handle unification of `IntVar` and `FloatVar`. - self.infcx.super_combine_tys(self, a, b) + self.infcx.super_combine_tys(self, a, b)?; } } + + Ok(a) } #[instrument(skip(self), level = "trace")] @@ -669,6 +532,10 @@ impl<'tcx, D> ObligationEmittingRelation<'tcx> for TypeRelating<'_, 'tcx, D> where D: TypeRelatingDelegate<'tcx>, { + fn span(&self) -> Span { + self.delegate.span() + } + fn param_env(&self) -> ty::ParamEnv<'tcx> { self.delegate.param_env() } diff --git a/compiler/rustc_infer/src/infer/relate/sub.rs b/compiler/rustc_infer/src/infer/relate/sub.rs index 36876acd7c0..5bd3a238a67 100644 --- a/compiler/rustc_infer/src/infer/relate/sub.rs +++ b/compiler/rustc_infer/src/infer/relate/sub.rs @@ -6,6 +6,7 @@ use rustc_middle::ty::relate::{Cause, Relate, RelateResult, TypeRelation}; use rustc_middle::ty::visit::TypeVisitableExt; use rustc_middle::ty::TyVar; use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_span::Span; use std::mem; /// Ensures `a` is made a subtype of `b`. Returns `a` on success. @@ -103,12 +104,12 @@ impl<'tcx> TypeRelation<'tcx> for Sub<'_, '_, 'tcx> { Ok(a) } - (&ty::Infer(TyVar(a_id)), _) => { - self.fields.instantiate(b, ty::Contravariant, a_id, !self.a_is_expected)?; + (&ty::Infer(TyVar(a_vid)), _) => { + infcx.instantiate_ty_var(self, self.a_is_expected, a_vid, ty::Covariant, b)?; Ok(a) } - (_, &ty::Infer(TyVar(b_id))) => { - self.fields.instantiate(a, ty::Covariant, b_id, self.a_is_expected)?; + (_, &ty::Infer(TyVar(b_vid))) => { + infcx.instantiate_ty_var(self, !self.a_is_expected, b_vid, ty::Contravariant, a)?; Ok(a) } @@ -199,6 +200,10 @@ impl<'tcx> TypeRelation<'tcx> for Sub<'_, '_, 'tcx> { } impl<'tcx> ObligationEmittingRelation<'tcx> for Sub<'_, '_, 'tcx> { + fn span(&self) -> Span { + self.fields.trace.span() + } + fn param_env(&self) -> ty::ParamEnv<'tcx> { self.fields.param_env } diff --git a/tests/ui/coherence/occurs-check/associated-type.next.stderr b/tests/ui/coherence/occurs-check/associated-type.next.stderr index 65be4a9c884..e405f389f5e 100644 --- a/tests/ui/coherence/occurs-check/associated-type.next.stderr +++ b/tests/ui/coherence/occurs-check/associated-type.next.stderr @@ -1,11 +1,11 @@ WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) -WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!2_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) +WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!1_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) -WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!2_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) +WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!1_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) -WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!2_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) +WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!1_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) -WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!2_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) +WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!1_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) error[E0119]: conflicting implementations of trait `Overlap<for<'a> fn(&'a (), ())>` for type `for<'a> fn(&'a (), ())` --> $DIR/associated-type.rs:31:1 | diff --git a/tests/ui/coherence/occurs-check/associated-type.old.stderr b/tests/ui/coherence/occurs-check/associated-type.old.stderr index 8e852ec796e..4a67a777f10 100644 --- a/tests/ui/coherence/occurs-check/associated-type.old.stderr +++ b/tests/ui/coherence/occurs-check/associated-type.old.stderr @@ -1,11 +1,11 @@ WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) -WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!3_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) +WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!2_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) -WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!3_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) +WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!2_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) -WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!3_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) +WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!2_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, ReBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) -WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!3_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) +WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: Alias(Projection, AliasTy { args: [*const ?1t, RePlaceholder(!2_BoundRegion { var: 0, kind: BrNamed(DefId(0:27 ~ associated_type[f554]::{impl#3}::'a#1), 'a) })], def_id: DefId(0:5 ~ associated_type[f554]::ToUnit::Unit) }) error[E0119]: conflicting implementations of trait `Overlap<for<'a> fn(&'a (), _)>` for type `for<'a> fn(&'a (), _)` --> $DIR/associated-type.rs:31:1 | diff --git a/tests/ui/impl-trait/rpit/early_bound.rs b/tests/ui/impl-trait/rpit/early_bound.rs index 03bd64d4d76..6dda687929c 100644 --- a/tests/ui/impl-trait/rpit/early_bound.rs +++ b/tests/ui/impl-trait/rpit/early_bound.rs @@ -5,7 +5,6 @@ fn test<'a: 'a>(n: bool) -> impl Sized + 'a { let true = n else { loop {} }; let _ = || { let _ = identity::<&'a ()>(test(false)); - //~^ ERROR hidden type for `impl Sized + 'a` captures lifetime that does not appear in bounds }; loop {} } diff --git a/tests/ui/impl-trait/rpit/early_bound.stderr b/tests/ui/impl-trait/rpit/early_bound.stderr index 815368f250e..780dea4e284 100644 --- a/tests/ui/impl-trait/rpit/early_bound.stderr +++ b/tests/ui/impl-trait/rpit/early_bound.stderr @@ -1,14 +1,3 @@ -error[E0700]: hidden type for `impl Sized + 'a` captures lifetime that does not appear in bounds - --> $DIR/early_bound.rs:7:17 - | -LL | fn test<'a: 'a>(n: bool) -> impl Sized + 'a { - | -- --------------- opaque type defined here - | | - | hidden type `&'a ()` captures the lifetime `'a` as defined here -... -LL | let _ = identity::<&'a ()>(test(false)); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - error: concrete type differs from previous defining opaque type use --> $DIR/early_bound.rs:3:29 | @@ -21,6 +10,5 @@ note: previous use here LL | let _ = identity::<&'a ()>(test(false)); | ^^^^^^^^^^^ -error: aborting due to 2 previous errors +error: aborting due to 1 previous error -For more information about this error, try `rustc --explain E0700`. diff --git a/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.next.stderr b/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.next.stderr index aaadf604a80..cde925db184 100644 --- a/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.next.stderr +++ b/tests/ui/traits/next-solver/generalize/occurs-check-nested-alias.next.stderr @@ -1,8 +1,8 @@ -error[E0284]: type annotations needed: cannot satisfy `<<T as Id<_>>::Id as Unnormalizable>::Assoc == _` +error[E0284]: type annotations needed: cannot satisfy `_ == <<T as Id<_>>::Id as Unnormalizable>::Assoc` --> $DIR/occurs-check-nested-alias.rs:36:9 | LL | x = y; - | ^ cannot satisfy `<<T as Id<_>>::Id as Unnormalizable>::Assoc == _` + | ^ cannot satisfy `_ == <<T as Id<_>>::Id as Unnormalizable>::Assoc` error: aborting due to 1 previous error |