diff options
Diffstat (limited to '')
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/select/mod.rs | 149 |
1 files changed, 53 insertions, 96 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index 75bd2c89f..9ebff4892 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -20,7 +20,7 @@ use super::{ }; use crate::infer::{InferCtxt, InferOk, TypeFreshener}; -use crate::traits::error_reporting::InferCtxtExt; +use crate::traits::error_reporting::TypeErrCtxtExt; use crate::traits::project::ProjectAndUnifyResult; use crate::traits::project::ProjectionCacheKeyExt; use crate::traits::ProjectionCacheKey; @@ -35,9 +35,8 @@ use rustc_middle::mir::interpret::ErrorHandled; use rustc_middle::ty::abstract_const::NotConstEvaluatable; use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams}; use rustc_middle::ty::fold::BottomUpFolder; -use rustc_middle::ty::print::with_no_trimmed_paths; use rustc_middle::ty::relate::TypeRelation; -use rustc_middle::ty::subst::{Subst, SubstsRef}; +use rustc_middle::ty::SubstsRef; use rustc_middle::ty::{self, EarlyBinder, PolyProjectionPredicate, ToPolyTraitRef, ToPredicate}; use rustc_middle::ty::{Ty, TyCtxt, TypeFoldable, TypeVisitable}; use rustc_span::symbol::sym; @@ -94,7 +93,7 @@ impl IntercrateAmbiguityCause { } pub struct SelectionContext<'cx, 'tcx> { - infcx: &'cx InferCtxt<'cx, 'tcx>, + infcx: &'cx InferCtxt<'tcx>, /// Freshener used specifically for entries on the obligation /// stack. This ensures that all entries on the stack at one time @@ -215,7 +214,7 @@ enum BuiltinImplConditions<'tcx> { } impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { - pub fn new(infcx: &'cx InferCtxt<'cx, 'tcx>) -> SelectionContext<'cx, 'tcx> { + pub fn new(infcx: &'cx InferCtxt<'tcx>) -> SelectionContext<'cx, 'tcx> { SelectionContext { infcx, freshener: infcx.freshener_keep_static(), @@ -225,28 +224,16 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { } } - pub fn intercrate(infcx: &'cx InferCtxt<'cx, 'tcx>) -> SelectionContext<'cx, 'tcx> { - SelectionContext { - infcx, - freshener: infcx.freshener_keep_static(), - intercrate: true, - intercrate_ambiguity_causes: None, - query_mode: TraitQueryMode::Standard, - } + pub fn intercrate(infcx: &'cx InferCtxt<'tcx>) -> SelectionContext<'cx, 'tcx> { + SelectionContext { intercrate: true, ..SelectionContext::new(infcx) } } pub fn with_query_mode( - infcx: &'cx InferCtxt<'cx, 'tcx>, + infcx: &'cx InferCtxt<'tcx>, query_mode: TraitQueryMode, ) -> SelectionContext<'cx, 'tcx> { debug!(?query_mode, "with_query_mode"); - SelectionContext { - infcx, - freshener: infcx.freshener_keep_static(), - intercrate: false, - intercrate_ambiguity_causes: None, - query_mode, - } + SelectionContext { query_mode, ..SelectionContext::new(infcx) } } /// Enables tracking of intercrate ambiguity causes. See @@ -266,7 +253,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { self.intercrate_ambiguity_causes.take().unwrap_or_default() } - pub fn infcx(&self) -> &'cx InferCtxt<'cx, 'tcx> { + pub fn infcx(&self) -> &'cx InferCtxt<'tcx> { self.infcx } @@ -689,19 +676,21 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { } ty::PredicateKind::ConstEquate(c1, c2) => { + assert!( + self.tcx().features().generic_const_exprs, + "`ConstEquate` without a feature gate: {c1:?} {c2:?}", + ); debug!(?c1, ?c2, "evaluate_predicate_recursively: equating consts"); - if self.tcx().features().generic_const_exprs { - // FIXME: we probably should only try to unify abstract constants - // if the constants depend on generic parameters. - // - // Let's just see where this breaks :shrug: - if let (ty::ConstKind::Unevaluated(a), ty::ConstKind::Unevaluated(b)) = - (c1.kind(), c2.kind()) - { - if self.infcx.try_unify_abstract_consts(a, b, obligation.param_env) { - return Ok(EvaluatedToOk); - } + // FIXME: we probably should only try to unify abstract constants + // if the constants depend on generic parameters. + // + // Let's just see where this breaks :shrug: + if let (ty::ConstKind::Unevaluated(a), ty::ConstKind::Unevaluated(b)) = + (c1.kind(), c2.kind()) + { + if self.infcx.try_unify_abstract_consts(a, b, obligation.param_env) { + return Ok(EvaluatedToOk); } } @@ -741,7 +730,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { ) } (Err(ErrorHandled::TooGeneric), _) | (_, Err(ErrorHandled::TooGeneric)) => { - if c1.has_infer_types_or_consts() || c2.has_infer_types_or_consts() { + if c1.has_non_region_infer() || c2.has_non_region_infer() { Ok(EvaluatedToAmbig) } else { // Two different constants using generic parameters ~> error. @@ -839,7 +828,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { /// must be met of course). One obvious case this comes up is /// marker traits like `Send`. Think of a linked list: /// - /// struct List<T> { data: T, next: Option<Box<List<T>>> } + /// struct List<T> { data: T, next: Option<Box<List<T>>> } /// /// `Box<List<T>>` will be `Send` if `T` is `Send` and /// `Option<Box<List<T>>>` is `Send`, and in turn @@ -926,38 +915,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { let unbound_input_types = stack.fresh_trait_pred.skip_binder().trait_ref.substs.types().any(|ty| ty.is_fresh()); - if stack.obligation.polarity() != ty::ImplPolarity::Negative { - // This check was an imperfect workaround for a bug in the old - // intercrate mode; it should be removed when that goes away. - if unbound_input_types && self.intercrate { - debug!("evaluate_stack --> unbound argument, intercrate --> ambiguous",); - // Heuristics: show the diagnostics when there are no candidates in crate. - if self.intercrate_ambiguity_causes.is_some() { - debug!("evaluate_stack: intercrate_ambiguity_causes is some"); - if let Ok(candidate_set) = self.assemble_candidates(stack) { - if !candidate_set.ambiguous && candidate_set.vec.is_empty() { - let trait_ref = stack.obligation.predicate.skip_binder().trait_ref; - let self_ty = trait_ref.self_ty(); - let cause = with_no_trimmed_paths!({ - IntercrateAmbiguityCause::DownstreamCrate { - trait_desc: trait_ref.print_only_trait_path().to_string(), - self_desc: if self_ty.has_concrete_skeleton() { - Some(self_ty.to_string()) - } else { - None - }, - } - }); - - debug!(?cause, "evaluate_stack: pushing cause"); - self.intercrate_ambiguity_causes.as_mut().unwrap().insert(cause); - } - } - } - return Ok(EvaluatedToAmbig); - } - } - if unbound_input_types && stack.iter().skip(1).any(|prev| { stack.obligation.param_env == prev.obligation.param_env @@ -1140,7 +1097,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { ErrorGuaranteed::unchecked_claim_error_was_emitted(), )); } - self.infcx.report_overflow_error(error_obligation, true); + self.infcx.err_ctxt().report_overflow_error(error_obligation, true); } TraitQueryMode::Canonical => { return Err(OverflowError::Canonical); @@ -1192,8 +1149,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { ImplCandidate(def_id) if tcx.constness(def_id) == hir::Constness::Const => {} // const param ParamCandidate(trait_pred) if trait_pred.is_const_if_const() => {} + // const projection + ProjectionCandidate(_, ty::BoundConstness::ConstIfConst) => {} // auto trait impl - AutoImplCandidate(..) => {} + AutoImplCandidate => {} // generator, this will raise error in other places // or ignore error with const_async_blocks feature GeneratorCandidate => {} @@ -1399,7 +1358,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { fn match_projection_obligation_against_definition_bounds( &mut self, obligation: &TraitObligation<'tcx>, - ) -> smallvec::SmallVec<[usize; 2]> { + ) -> smallvec::SmallVec<[(usize, ty::BoundConstness); 2]> { let poly_trait_predicate = self.infcx().resolve_vars_if_possible(obligation.predicate); let placeholder_trait_predicate = self.infcx().replace_bound_vars_with_placeholders(poly_trait_predicate); @@ -1447,7 +1406,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { _ => false, } }) { - return Some(idx); + return Some((idx, pred.constness)); } } None @@ -1563,7 +1522,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { if !generics.params.is_empty() && obligation.predicate.substs[generics.parent_count..] .iter() - .any(|&p| p.has_infer_types_or_consts() && self.infcx.shallow_resolve(p) != p) + .any(|&p| p.has_non_region_infer() && self.infcx.shallow_resolve(p) != p) { ProjectionMatchesProjection::Ambiguous } else { @@ -1605,13 +1564,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { }; // (*) Prefer `BuiltinCandidate { has_nested: false }`, `PointeeCandidate`, - // `DiscriminantKindCandidate`, `ConstDestructCandidate`, and `TupleCandidate` + // `DiscriminantKindCandidate`, `ConstDestructCandidate` // to anything else. // // This is a fix for #53123 and prevents winnowing from accidentally extending the // lifetime of a variable. match (&other.candidate, &victim.candidate) { - (_, AutoImplCandidate(..)) | (AutoImplCandidate(..), _) => { + (_, AutoImplCandidate) | (AutoImplCandidate, _) => { bug!( "default implementations shouldn't be recorded \ when there are other valid candidates" @@ -1626,8 +1585,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { BuiltinCandidate { has_nested: false } | DiscriminantKindCandidate | PointeeCandidate - | ConstDestructCandidate(_) - | TupleCandidate, + | ConstDestructCandidate(_), _, ) => true, ( @@ -1635,8 +1593,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { BuiltinCandidate { has_nested: false } | DiscriminantKindCandidate | PointeeCandidate - | ConstDestructCandidate(_) - | TupleCandidate, + | ConstDestructCandidate(_), ) => false, (ParamCandidate(other), ParamCandidate(victim)) => { @@ -1681,11 +1638,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { | BuiltinUnsizeCandidate | TraitUpcastingUnsizeCandidate(_) | BuiltinCandidate { .. } - | TraitAliasCandidate(..) + | TraitAliasCandidate | ObjectCandidate(_) - | ProjectionCandidate(_), + | ProjectionCandidate(..), ) => !is_global(cand), - (ObjectCandidate(_) | ProjectionCandidate(_), ParamCandidate(ref cand)) => { + (ObjectCandidate(_) | ProjectionCandidate(..), ParamCandidate(ref cand)) => { // Prefer these to a global where-clause bound // (see issue #50825). is_global(cand) @@ -1699,7 +1656,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { | BuiltinUnsizeCandidate | TraitUpcastingUnsizeCandidate(_) | BuiltinCandidate { has_nested: true } - | TraitAliasCandidate(..), + | TraitAliasCandidate, ParamCandidate(ref cand), ) => { // Prefer these to a global where-clause bound @@ -1707,20 +1664,20 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { is_global(cand) && other.evaluation.must_apply_modulo_regions() } - (ProjectionCandidate(i), ProjectionCandidate(j)) + (ProjectionCandidate(i, _), ProjectionCandidate(j, _)) | (ObjectCandidate(i), ObjectCandidate(j)) => { // Arbitrarily pick the lower numbered candidate for backwards // compatibility reasons. Don't let this affect inference. i < j && !needs_infer } - (ObjectCandidate(_), ProjectionCandidate(_)) - | (ProjectionCandidate(_), ObjectCandidate(_)) => { + (ObjectCandidate(_), ProjectionCandidate(..)) + | (ProjectionCandidate(..), ObjectCandidate(_)) => { bug!("Have both object and projection candidate") } // Arbitrarily give projection and object candidates priority. ( - ObjectCandidate(_) | ProjectionCandidate(_), + ObjectCandidate(_) | ProjectionCandidate(..), ImplCandidate(..) | ClosureCandidate | GeneratorCandidate @@ -1729,7 +1686,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { | BuiltinUnsizeCandidate | TraitUpcastingUnsizeCandidate(_) | BuiltinCandidate { .. } - | TraitAliasCandidate(..), + | TraitAliasCandidate, ) => true, ( @@ -1741,18 +1698,18 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { | BuiltinUnsizeCandidate | TraitUpcastingUnsizeCandidate(_) | BuiltinCandidate { .. } - | TraitAliasCandidate(..), - ObjectCandidate(_) | ProjectionCandidate(_), + | TraitAliasCandidate, + ObjectCandidate(_) | ProjectionCandidate(..), ) => false, (&ImplCandidate(other_def), &ImplCandidate(victim_def)) => { // See if we can toss out `victim` based on specialization. - // This requires us to know *for sure* that the `other` impl applies - // i.e., `EvaluatedToOk`. + // While this requires us to know *for sure* that the `other` impl applies + // we still use modulo regions here. // - // FIXME(@lcnr): Using `modulo_regions` here seems kind of scary - // to me but is required for `std` to compile, so I didn't change it - // for now. + // This is fine as specialization currently assumes that specializing + // impls have to be always applicable, meaning that the only allowed + // region constraints may be constraints also present on the default impl. let tcx = self.tcx(); if other.evaluation.must_apply_modulo_regions() { if tcx.specializes((other_def, victim_def)) { @@ -1822,7 +1779,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { | BuiltinUnsizeCandidate | TraitUpcastingUnsizeCandidate(_) | BuiltinCandidate { has_nested: true } - | TraitAliasCandidate(..), + | TraitAliasCandidate, ImplCandidate(_) | ClosureCandidate | GeneratorCandidate @@ -1831,7 +1788,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { | BuiltinUnsizeCandidate | TraitUpcastingUnsizeCandidate(_) | BuiltinCandidate { has_nested: true } - | TraitAliasCandidate(..), + | TraitAliasCandidate, ) => false, } } |