| use std::debug_assert_matches; |
| |
| use rustc_type_ir::fast_reject::DeepRejectCtxt; |
| use rustc_type_ir::inherent::*; |
| use rustc_type_ir::lang_items::{SolverAdtLangItem, SolverProjectionLangItem, SolverTraitLangItem}; |
| use rustc_type_ir::solve::{ |
| FetchEligibleAssocItemResponse, NoSolutionOrRerunNonErased, QueryResultOrRerunNonErased, |
| RerunNonErased, RerunReason, RerunResultExt, |
| }; |
| use rustc_type_ir::{ |
| self as ty, FieldInfo, Interner, NormalizesTo, PredicateKind, Unnormalized, Upcast as _, |
| }; |
| use tracing::instrument; |
| |
| use crate::delegate::SolverDelegate; |
| use crate::solve::assembly::structural_traits::{self, AsyncCallableRelevantTypes}; |
| use crate::solve::assembly::{self, Candidate}; |
| use crate::solve::inspect::ProbeKind; |
| use crate::solve::{ |
| BuiltinImplSource, CandidateSource, Certainty, EvalCtxt, Goal, GoalSource, MaybeInfo, |
| NoSolution, SizedTraitKind, |
| }; |
| |
| impl<D, I> EvalCtxt<'_, D> |
| where |
| D: SolverDelegate<Interner = I>, |
| I: Interner, |
| { |
| #[instrument(level = "trace", skip(self), ret)] |
| pub(super) fn compute_normalizes_to_goal( |
| &mut self, |
| goal: Goal<I, NormalizesTo<I>>, |
| ) -> QueryResultOrRerunNonErased<I> { |
| debug_assert!(self.term_is_fully_unconstrained(goal)); |
| debug_assert_matches!( |
| goal.predicate.alias.kind, |
| ty::AliasTermKind::ProjectionTy { .. } | ty::AliasTermKind::ProjectionConst { .. } |
| ); |
| |
| let cx = self.cx(); |
| |
| let trait_ref = goal.predicate.alias.trait_ref(cx); |
| let (_, proven_via) = self.probe(|_| ProbeKind::ShadowedEnvProbing).enter(|ecx| { |
| let trait_goal: Goal<I, ty::TraitPredicate<I>> = goal.with(cx, trait_ref); |
| ecx.compute_trait_goal(trait_goal) |
| })?; |
| self.assemble_and_merge_candidates( |
| proven_via, |
| goal, |
| |ecx| { |
| // FIXME(generic_associated_types): Addresses aggressive inference in #92917. |
| // |
| // If this type is a GAT with currently unconstrained arguments, we do not |
| // want to normalize it via a candidate which only applies for a specific |
| // instantiation. We could otherwise keep the GAT as rigid and succeed this way. |
| // See tests/ui/generic-associated-types/no-incomplete-gat-arg-inference.rs. |
| // |
| // This only avoids normalization if a GAT argument is fully unconstrained. |
| // This is quite arbitrary but fixing it causes some ambiguity, see #125196. |
| for arg in goal.predicate.alias.own_args(cx).iter() { |
| let Some(term) = arg.as_term() else { |
| continue; |
| }; |
| match ecx.structurally_normalize_term(goal.param_env, term) { |
| Ok(term) => { |
| if term.is_infer() { |
| return Some(ecx.evaluate_added_goals_and_make_canonical_response( |
| Certainty::AMBIGUOUS, |
| )); |
| } |
| } |
| Err( |
| e @ (NoSolutionOrRerunNonErased::NoSolution(NoSolution) |
| | NoSolutionOrRerunNonErased::RerunNonErased(_)), |
| ) => { |
| return Some(Err(e)); |
| } |
| } |
| } |
| |
| None |
| }, |
| |ecx| { |
| ecx.probe(|&result| ProbeKind::RigidAlias { result }) |
| .enter(|this| { |
| this.structurally_instantiate_normalizes_to_term( |
| goal, |
| goal.predicate.alias, |
| ); |
| this.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| .map_err(Into::into) |
| }, |
| ) |
| } |
| |
| /// When normalizing a const alias, register a `ConstArgHasType` goal |
| /// to ensure the const value's type matches the declared type. |
| pub fn push_const_arg_has_type_goal( |
| &mut self, |
| param_env: I::ParamEnv, |
| alias: ty::AliasTerm<I>, |
| term: I::Term, |
| ) { |
| if let Some(ct) = term.as_const() { |
| let cx = self.cx(); |
| let expected_ty = alias.expect_ct().type_of(cx).skip_norm_wip(); |
| self.add_goal( |
| GoalSource::Misc, |
| Goal { |
| param_env, |
| predicate: ty::ClauseKind::ConstArgHasType(ct, expected_ty).upcast(cx), |
| }, |
| ); |
| } |
| } |
| |
| /// When normalizing an associated item, constrain the expected term to `term`. |
| /// |
| /// We know `term` to always be a fully unconstrained inference variable, so |
| /// `eq` should never fail here. However, in case `term` contains aliases, we |
| /// emit nested `AliasRelate` goals to structurally normalize the alias. |
| /// |
| /// Additionally, when `term` is a const, this registers a `ConstArgHasType` |
| /// goal to ensure that the const value's type matches the declared type of |
| /// the alias it was normalized from. |
| /// |
| /// You may reasonably wonder: shouldn't `wfcheck::check_type_const` already |
| /// catch any such type mismatch at the definition site, so that the |
| /// definition is tainted and we never even attempt to normalize a reference |
| /// to it? In principle that's exactly what should happen. However, we cannot |
| /// simply force the defining item's wfcheck to run before all uses are |
| /// normalized: wfcheck itself may depend on typeck, trait solving, and |
| /// normalization, so enforcing such a strict ordering would easily create |
| /// query cycles. |
| /// |
| /// However, when CTFE runs on a MIR body, normalizing a type const within |
| /// that body can change the type of the resulting value, causing the MIR |
| /// to become ill-formed. If `check_type_const` for that alias has not yet |
| /// reported its error, no prior error has been recorded and MIR validation |
| /// fires a `span_bug!`. Registering the obligation here ensures the type |
| /// mismatch is reported during normalization itself, tainting the MIR |
| /// before validation runs. |
| fn instantiate_normalizes_to_term(&mut self, goal: Goal<I, NormalizesTo<I>>, term: I::Term) { |
| self.push_const_arg_has_type_goal(goal.param_env, goal.predicate.alias, term); |
| self.eq(goal.param_env, goal.predicate.term, term) |
| .expect("expected goal term to be fully unconstrained"); |
| } |
| |
| /// Unlike `instantiate_normalizes_to_term` this instantiates the expected term |
| /// with a rigid alias. Using this is pretty much always wrong. |
| fn structurally_instantiate_normalizes_to_term( |
| &mut self, |
| goal: Goal<I, NormalizesTo<I>>, |
| term: ty::AliasTerm<I>, |
| ) { |
| self.relate_rigid_alias_non_alias(goal.param_env, term, ty::Invariant, goal.predicate.term) |
| .expect("expected goal term to be fully unconstrained"); |
| } |
| } |
| |
| impl<D, I> assembly::GoalKind<D> for NormalizesTo<I> |
| where |
| D: SolverDelegate<Interner = I>, |
| I: Interner, |
| { |
| fn self_ty(self) -> I::Ty { |
| self.self_ty() |
| } |
| |
| fn trait_ref(self, cx: I) -> ty::TraitRef<I> { |
| self.alias.trait_ref(cx) |
| } |
| |
| fn with_replaced_self_ty(self, cx: I, self_ty: I::Ty) -> Self { |
| self.with_replaced_self_ty(cx, self_ty) |
| } |
| |
| fn trait_def_id(self, cx: I) -> I::TraitId { |
| self.trait_def_id(cx) |
| } |
| |
| fn fast_reject_assumption( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| assumption: I::Clause, |
| ) -> Result<(), NoSolution> { |
| let alias_def_id = match goal.predicate.alias.kind { |
| ty::AliasTermKind::ProjectionTy { def_id } => def_id.into(), |
| ty::AliasTermKind::ProjectionConst { def_id } => def_id.into(), |
| _ => return Err(NoSolution), |
| }; |
| if let Some(projection_pred) = assumption.as_projection_clause() |
| && projection_pred.item_def_id() == alias_def_id |
| && DeepRejectCtxt::relate_rigid_rigid(ecx.cx()).args_may_unify( |
| goal.predicate.alias.args, |
| projection_pred.skip_binder().projection_term.args, |
| ) |
| { |
| Ok(()) |
| } else { |
| Err(NoSolution) |
| } |
| } |
| |
| fn match_assumption( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| assumption: I::Clause, |
| then: impl FnOnce(&mut EvalCtxt<'_, D>) -> QueryResultOrRerunNonErased<I>, |
| ) -> QueryResultOrRerunNonErased<I> { |
| let cx = ecx.cx(); |
| let projection_pred = assumption.as_projection_clause().unwrap(); |
| let assumption_projection_pred = ecx.instantiate_binder_with_infer(projection_pred); |
| ecx.eq(goal.param_env, goal.predicate.alias, assumption_projection_pred.projection_term)?; |
| |
| ecx.instantiate_normalizes_to_term(goal, assumption_projection_pred.term); |
| |
| // Add GAT where clauses from the trait's definition |
| // FIXME: We don't need these, since these are the type's own WF obligations. |
| ecx.add_goals( |
| GoalSource::AliasWellFormed, |
| cx.own_predicates_of(goal.predicate.alias.expect_projection_def_id().into()) |
| .iter_instantiated(cx, goal.predicate.alias.args) |
| .map(Unnormalized::skip_norm_wip) |
| .map(|pred| goal.with(cx, pred)), |
| ); |
| |
| then(ecx) |
| } |
| |
| // Hack for trait-system-refactor-initiative#245. |
| // FIXME(-Zhigher-ranked-assumptions): this impl differs from trait goals and we should unify |
| // them again once we properly support binders. |
| fn probe_and_consider_object_bound_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| source: CandidateSource<I>, |
| goal: Goal<I, Self>, |
| assumption: I::Clause, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| Self::probe_and_match_goal_against_assumption(ecx, source, goal, assumption, |ecx| { |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| } |
| |
| fn consider_additional_alias_assumptions( |
| _ecx: &mut EvalCtxt<'_, D>, |
| _goal: Goal<I, Self>, |
| _alias_ty: ty::AliasTy<I>, |
| ) -> Vec<Candidate<I>> { |
| vec![] |
| } |
| |
| fn consider_impl_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, NormalizesTo<I>>, |
| impl_def_id: I::ImplId, |
| then: impl FnOnce(&mut EvalCtxt<'_, D>, Certainty) -> QueryResultOrRerunNonErased<I>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let cx = ecx.cx(); |
| |
| let alias_def_id = goal.predicate.alias.expect_projection_def_id(); |
| let goal_trait_ref = goal.predicate.alias.trait_ref(cx); |
| let impl_trait_ref = cx.impl_trait_ref(impl_def_id); |
| if !DeepRejectCtxt::relate_rigid_infer(ecx.cx()).args_may_unify( |
| goal.predicate.alias.trait_ref(cx).args, |
| impl_trait_ref.skip_binder().args, |
| ) { |
| return Err(NoSolution.into()); |
| } |
| |
| // We have to ignore negative impls when projecting. |
| let impl_polarity = cx.impl_polarity(impl_def_id); |
| match impl_polarity { |
| ty::ImplPolarity::Negative => return Err(NoSolution.into()), |
| ty::ImplPolarity::Reservation => { |
| unimplemented!("reservation impl for trait with assoc item: {:?}", goal) |
| } |
| ty::ImplPolarity::Positive => {} |
| }; |
| |
| ecx.probe_trait_candidate(CandidateSource::Impl(impl_def_id)).enter(|ecx| { |
| let impl_args = ecx.fresh_args_for_item(impl_def_id.into()); |
| let impl_trait_ref = impl_trait_ref.instantiate(cx, impl_args).skip_norm_wip(); |
| |
| ecx.eq(goal.param_env, goal_trait_ref, impl_trait_ref)?; |
| |
| let where_clause_bounds = cx |
| .predicates_of(impl_def_id.into()) |
| .iter_instantiated(cx, impl_args) |
| .map(Unnormalized::skip_norm_wip) |
| .map(|pred| goal.with(cx, pred)); |
| ecx.add_goals(GoalSource::ImplWhereBound, where_clause_bounds); |
| |
| // Bail if the nested goals don't hold here. This is to avoid unnecessarily |
| // computing the `type_of` query for associated types that never apply, as |
| // this may result in query cycles in the case of RPITITs. |
| // See <https://github.com/rust-lang/trait-system-refactor-initiative/issues/185>. |
| ecx.try_evaluate_added_goals()?; |
| |
| // Add GAT where clauses from the trait's definition. This is necessary |
| // for soundness until we properly handle implied bounds on binders, |
| // see tests/ui/generic-associated-types/must-prove-where-clauses-on-norm.rs. |
| ecx.add_goals( |
| GoalSource::AliasWellFormed, |
| cx.own_predicates_of(alias_def_id.into()) |
| .iter_instantiated(cx, goal.predicate.alias.args) |
| .map(Unnormalized::skip_norm_wip) |
| .map(|pred| goal.with(cx, pred)), |
| ); |
| |
| let error_response = |ecx: &mut EvalCtxt<'_, D>, guar| { |
| let error_term = match goal.predicate.alias.kind { |
| ty::AliasTermKind::ProjectionTy { .. } => Ty::new_error(cx, guar).into(), |
| ty::AliasTermKind::ProjectionConst { .. } => Const::new_error(cx, guar).into(), |
| kind => panic!("expected projection, found {kind:?}"), |
| }; |
| ecx.instantiate_normalizes_to_term(goal, error_term); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }; |
| |
| let target_item_def_id = |
| match ecx.fetch_eligible_assoc_item(goal_trait_ref, alias_def_id, impl_def_id) { |
| FetchEligibleAssocItemResponse::Found(target_item_def_id) => target_item_def_id, |
| FetchEligibleAssocItemResponse::NotFound(tm) => { |
| match tm { |
| // In case the associated item is hidden due to specialization, |
| // normalizing this associated item is always ambiguous. Treating |
| // the associated item as rigid would be incomplete and allow for |
| // overlapping impls, see #105782. |
| // |
| // As this ambiguity is unavoidable we emit a nested ambiguous |
| // goal instead of using `Certainty::AMBIGUOUS`. This allows us to |
| // return the nested goals to the parent `AliasRelate` goal. This |
| // would be relevant if any of the nested goals refer to the `term`. |
| // This is not the case here and we only prefer adding an ambiguous |
| // nested goal for consistency. |
| ty::TypingMode::Coherence => { |
| ecx.add_goal( |
| GoalSource::Misc, |
| goal.with(cx, PredicateKind::Ambiguous), |
| ); |
| return ecx |
| .evaluate_added_goals_and_make_canonical_response( |
| Certainty::Yes, |
| ) |
| .map_err(Into::into); |
| } |
| // Outside of coherence, we treat the associated item as rigid instead. |
| ty::TypingMode::Typeck { .. } |
| | ty::TypingMode::PostTypeckUntilBorrowck { .. } |
| | ty::TypingMode::PostBorrowck { .. } |
| | ty::TypingMode::PostAnalysis |
| | ty::TypingMode::Codegen => { |
| ecx.structurally_instantiate_normalizes_to_term( |
| goal, |
| goal.predicate.alias, |
| ); |
| return ecx |
| .evaluate_added_goals_and_make_canonical_response( |
| Certainty::Yes, |
| ) |
| .map_err(Into::into); |
| } |
| }; |
| } |
| FetchEligibleAssocItemResponse::Err(guar) => return error_response(ecx, guar), |
| FetchEligibleAssocItemResponse::NotFoundBecauseErased => { |
| ecx.opaque_accesses.rerun_always(RerunReason::FetchEligibleAssocItem)?; |
| return Err(NoSolution.into()); |
| } |
| }; |
| |
| if !cx.has_item_definition(target_item_def_id) { |
| // If the impl is missing an item, it's either because the user forgot to |
| // provide it, or the user is not *obligated* to provide it (because it |
| // has a trivially false `Sized` predicate). If it's the latter, we cannot |
| // delay a bug because we can have trivially false where clauses, so we |
| // treat it as rigid. |
| if cx.impl_self_is_guaranteed_unsized(impl_def_id) { |
| if ecx.typing_mode().is_coherence() { |
| // Trying to normalize such associated items is always ambiguous |
| // during coherence to avoid cyclic reasoning. See the example in |
| // tests/ui/traits/trivial-unsized-projection-in-coherence.rs. |
| // |
| // As this ambiguity is unavoidable we emit a nested ambiguous |
| // goal instead of using `Certainty::AMBIGUOUS`. This allows us to |
| // return the nested goals to the parent `AliasRelate` goal. This |
| // would be relevant if any of the nested goals refer to the `term`. |
| // This is not the case here and we only prefer adding an ambiguous |
| // nested goal for consistency. |
| ecx.add_goal(GoalSource::Misc, goal.with(cx, PredicateKind::Ambiguous)); |
| return then(ecx, Certainty::Yes).map_err(Into::into); |
| } else { |
| ecx.structurally_instantiate_normalizes_to_term(goal, goal.predicate.alias); |
| return then(ecx, Certainty::Yes).map_err(Into::into); |
| } |
| } else { |
| return error_response(ecx, cx.delay_bug("missing item")); |
| } |
| } |
| |
| let target_container_def_id = cx.impl_or_trait_assoc_term_parent(target_item_def_id); |
| |
| // Getting the right args here is complex, e.g. given: |
| // - a goal `<Vec<u32> as Trait<i32>>::Assoc<u64>` |
| // - the applicable impl `impl<T> Trait<i32> for Vec<T>` |
| // - and the impl which defines `Assoc` being `impl<T, U> Trait<U> for Vec<T>` |
| // |
| // We first rebase the goal args onto the impl, going from `[Vec<u32>, i32, u64]` |
| // to `[u32, u64]`. |
| // |
| // And then map these args to the args of the defining impl of `Assoc`, going |
| // from `[u32, u64]` to `[u32, i32, u64]`. |
| let target_args = ecx.translate_args( |
| goal, |
| impl_def_id, |
| impl_args, |
| impl_trait_ref, |
| target_container_def_id, |
| )?; |
| |
| if !cx.check_args_compatible(target_item_def_id.into(), target_args) { |
| return error_response( |
| ecx, |
| cx.delay_bug("associated item has mismatched arguments"), |
| ); |
| } |
| |
| // Finally we construct the actual value of the associated type. |
| let term = match goal.predicate.alias.kind { |
| ty::AliasTermKind::ProjectionTy { .. } => cx |
| .type_of(target_item_def_id.into()) |
| .instantiate(cx, target_args) |
| .skip_norm_wip() |
| .into(), |
| ty::AliasTermKind::ProjectionConst { .. } |
| if cx.is_type_const(target_item_def_id.into()) => |
| { |
| cx.const_of_item(target_item_def_id.into()) |
| .instantiate(cx, target_args) |
| .skip_norm_wip() |
| .into() |
| } |
| ty::AliasTermKind::ProjectionConst { .. } => { |
| let uv = ty::UnevaluatedConst::new( |
| cx, |
| ty::UnevaluatedConstKind::Projection { |
| def_id: target_item_def_id.into().try_into().unwrap(), |
| }, |
| target_args, |
| ); |
| return ecx.evaluate_const_and_instantiate_projection_term( |
| goal.param_env, |
| goal.predicate.alias, |
| goal.predicate.term, |
| uv, |
| ); |
| } |
| kind => panic!("expected projection, found {kind:?}"), |
| }; |
| |
| ecx.instantiate_normalizes_to_term(goal, term); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes).map_err(Into::into) |
| }) |
| } |
| |
| /// Fail to normalize if the predicate contains an error, alternatively, we could normalize to `ty::Error` |
| /// and succeed. Can experiment with this to figure out what results in better error messages. |
| fn consider_error_guaranteed_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| guar: I::ErrorGuaranteed, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let cx = ecx.cx(); |
| let error_term = match goal.predicate.alias.kind { |
| ty::AliasTermKind::ProjectionTy { .. } => Ty::new_error(cx, guar).into(), |
| ty::AliasTermKind::ProjectionConst { .. } => Const::new_error(cx, guar).into(), |
| kind => panic!("expected projection, found {kind:?}"), |
| }; |
| |
| ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| { |
| ecx.instantiate_normalizes_to_term(goal, error_term); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| } |
| |
| fn consider_auto_trait_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| _goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| ecx.cx().delay_bug("associated types not allowed on auto traits"); |
| Err(NoSolution.into()) |
| } |
| |
| fn consider_trait_alias_candidate( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| panic!("trait aliases do not have associated types: {:?}", goal); |
| } |
| |
| fn consider_builtin_sizedness_candidates( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| _sizedness: SizedTraitKind, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| panic!("`Sized`/`MetaSized` does not have an associated type: {:?}", goal); |
| } |
| |
| fn consider_builtin_copy_clone_candidate( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| panic!("`Copy`/`Clone` does not have an associated type: {:?}", goal); |
| } |
| |
| fn consider_builtin_fn_ptr_trait_candidate( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| panic!("`FnPtr` does not have an associated type: {:?}", goal); |
| } |
| |
| fn consider_builtin_fn_trait_candidates( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| goal_kind: ty::ClosureKind, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let cx = ecx.cx(); |
| let Some(tupled_inputs_and_output) = |
| structural_traits::extract_tupled_inputs_and_output_from_callable( |
| cx, |
| goal.predicate.self_ty(), |
| goal_kind, |
| )? |
| else { |
| return ecx.forced_ambiguity(MaybeInfo::AMBIGUOUS); |
| }; |
| let (inputs, output) = ecx.instantiate_binder_with_infer(tupled_inputs_and_output); |
| |
| // A built-in `Fn` impl only holds if the output is sized. |
| // (FIXME: technically we only need to check this if the type is a fn ptr...) |
| let output_is_sized_pred = |
| ty::TraitRef::new(cx, cx.require_trait_lang_item(SolverTraitLangItem::Sized), [output]); |
| |
| let pred = ty::ProjectionPredicate { |
| projection_term: ty::AliasTerm::new( |
| cx, |
| goal.predicate.alias.kind, |
| [goal.predicate.self_ty(), inputs], |
| ), |
| term: output.into(), |
| } |
| .upcast(cx); |
| |
| Self::probe_and_consider_implied_clause( |
| ecx, |
| CandidateSource::BuiltinImpl(BuiltinImplSource::Misc), |
| goal, |
| pred, |
| [(GoalSource::ImplWhereBound, goal.with(cx, output_is_sized_pred))], |
| ) |
| .map_err(Into::into) |
| } |
| |
| fn consider_builtin_async_fn_trait_candidates( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| goal_kind: ty::ClosureKind, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let cx = ecx.cx(); |
| let def_id = goal.predicate.alias.expect_projection_ty_def_id(); |
| |
| let env_region = match goal_kind { |
| ty::ClosureKind::Fn | ty::ClosureKind::FnMut => goal.predicate.alias.args.region_at(2), |
| // Doesn't matter what this region is |
| ty::ClosureKind::FnOnce => Region::new_static(cx), |
| }; |
| let (tupled_inputs_and_output_and_coroutine, nested_preds) = |
| structural_traits::extract_tupled_inputs_and_output_from_async_callable( |
| cx, |
| goal.predicate.self_ty(), |
| goal_kind, |
| env_region, |
| )?; |
| let AsyncCallableRelevantTypes { |
| tupled_inputs_ty, |
| output_coroutine_ty, |
| coroutine_return_ty, |
| } = ecx.instantiate_binder_with_infer(tupled_inputs_and_output_and_coroutine); |
| |
| // A built-in `AsyncFn` impl only holds if the output is sized. |
| // (FIXME: technically we only need to check this if the type is a fn ptr...) |
| let output_is_sized_pred = ty::TraitRef::new( |
| cx, |
| cx.require_trait_lang_item(SolverTraitLangItem::Sized), |
| [output_coroutine_ty], |
| ); |
| |
| let (projection_term, term) = if cx |
| .is_projection_lang_item(def_id, SolverProjectionLangItem::CallOnceFuture) |
| { |
| ( |
| ty::AliasTerm::new( |
| cx, |
| goal.predicate.alias.kind, |
| [goal.predicate.self_ty(), tupled_inputs_ty], |
| ), |
| output_coroutine_ty.into(), |
| ) |
| } else if cx.is_projection_lang_item(def_id, SolverProjectionLangItem::CallRefFuture) { |
| ( |
| ty::AliasTerm::new( |
| cx, |
| goal.predicate.alias.kind, |
| [ |
| I::GenericArg::from(goal.predicate.self_ty()), |
| tupled_inputs_ty.into(), |
| env_region.into(), |
| ], |
| ), |
| output_coroutine_ty.into(), |
| ) |
| } else if cx.is_projection_lang_item(def_id, SolverProjectionLangItem::AsyncFnOnceOutput) { |
| ( |
| ty::AliasTerm::new( |
| cx, |
| goal.predicate.alias.kind, |
| [goal.predicate.self_ty(), tupled_inputs_ty], |
| ), |
| coroutine_return_ty.into(), |
| ) |
| } else { |
| panic!("no such associated type in `AsyncFn*`: {:?}", def_id) |
| }; |
| let pred = ty::ProjectionPredicate { projection_term, term }.upcast(cx); |
| |
| Self::probe_and_consider_implied_clause( |
| ecx, |
| CandidateSource::BuiltinImpl(BuiltinImplSource::Misc), |
| goal, |
| pred, |
| [goal.with(cx, output_is_sized_pred)] |
| .into_iter() |
| .chain(nested_preds.into_iter().map(|pred| goal.with(cx, pred))) |
| .map(|goal| (GoalSource::ImplWhereBound, goal)), |
| ) |
| } |
| |
| fn consider_builtin_async_fn_kind_helper_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let [ |
| closure_fn_kind_ty, |
| goal_kind_ty, |
| borrow_region, |
| tupled_inputs_ty, |
| tupled_upvars_ty, |
| coroutine_captures_by_ref_ty, |
| ] = *goal.predicate.alias.args.as_slice() |
| else { |
| panic!(); |
| }; |
| |
| // Bail if the upvars haven't been constrained. |
| if tupled_upvars_ty.expect_ty().is_ty_var() { |
| return ecx.forced_ambiguity(MaybeInfo::AMBIGUOUS); |
| } |
| |
| let Some(closure_kind) = closure_fn_kind_ty.expect_ty().to_opt_closure_kind() else { |
| // We don't need to worry about the self type being an infer var. |
| return Err(NoSolution.into()); |
| }; |
| let Some(goal_kind) = goal_kind_ty.expect_ty().to_opt_closure_kind() else { |
| return Err(NoSolution.into()); |
| }; |
| if !closure_kind.extends(goal_kind) { |
| return Err(NoSolution.into()); |
| } |
| |
| let upvars_ty = ty::CoroutineClosureSignature::tupled_upvars_by_closure_kind( |
| ecx.cx(), |
| goal_kind, |
| tupled_inputs_ty.expect_ty(), |
| tupled_upvars_ty.expect_ty(), |
| coroutine_captures_by_ref_ty.expect_ty(), |
| borrow_region.expect_region(), |
| ); |
| |
| ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| { |
| ecx.instantiate_normalizes_to_term(goal, upvars_ty.into()); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| } |
| |
| fn consider_builtin_tuple_candidate( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| panic!("`Tuple` does not have an associated type: {:?}", goal); |
| } |
| |
| fn consider_builtin_pointee_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let cx = ecx.cx(); |
| let metadata_def_id = cx.require_projection_lang_item(SolverProjectionLangItem::Metadata); |
| assert_eq!( |
| ty::AliasTermKind::ProjectionTy { def_id: metadata_def_id }, |
| goal.predicate.alias.kind |
| ); |
| let metadata_ty = match goal.predicate.self_ty().kind() { |
| ty::Bool |
| | ty::Char |
| | ty::Int(..) |
| | ty::Uint(..) |
| | ty::Float(..) |
| | ty::Array(..) |
| | ty::Pat(..) |
| | ty::RawPtr(..) |
| | ty::Ref(..) |
| | ty::FnDef(..) |
| | ty::FnPtr(..) |
| | ty::Closure(..) |
| | ty::CoroutineClosure(..) |
| | ty::Infer(ty::IntVar(..) | ty::FloatVar(..)) |
| | ty::Coroutine(..) |
| | ty::CoroutineWitness(..) |
| | ty::Never |
| | ty::Foreign(..) => Ty::new_unit(cx), |
| |
| ty::Error(e) => Ty::new_error(cx, e), |
| |
| ty::Str | ty::Slice(_) => Ty::new_usize(cx), |
| |
| ty::Dynamic(_, _) => { |
| let dyn_metadata = cx.require_adt_lang_item(SolverAdtLangItem::DynMetadata); |
| cx.type_of(dyn_metadata.into()) |
| .instantiate(cx, &[I::GenericArg::from(goal.predicate.self_ty())]) |
| .skip_norm_wip() |
| } |
| |
| ty::Alias(_) | ty::Param(_) | ty::Placeholder(..) => { |
| // This is the "fallback impl" for type parameters, unnormalizable projections |
| // and opaque types: If the `self_ty` is `Sized`, then the metadata is `()`. |
| // FIXME(ptr_metadata): This impl overlaps with the other impls and shouldn't |
| // exist. Instead, `Pointee<Metadata = ()>` should be a supertrait of `Sized`. |
| let alias_bound_result = |
| ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| { |
| let sized_predicate = ty::TraitRef::new( |
| cx, |
| cx.require_trait_lang_item(SolverTraitLangItem::Sized), |
| [I::GenericArg::from(goal.predicate.self_ty())], |
| ); |
| ecx.add_goal(GoalSource::Misc, goal.with(cx, sized_predicate)); |
| ecx.instantiate_normalizes_to_term(goal, Ty::new_unit(cx).into()); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }); |
| |
| let alias_bound_result = match alias_bound_result.map_err_to_rerun()? { |
| Ok(i) => Ok(i), |
| Err(NoSolution) => Err(NoSolution), |
| }; |
| |
| // In case the dummy alias-bound candidate does not apply, we instead treat this projection |
| // as rigid. |
| return alias_bound_result.or_else(|NoSolution| { |
| ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|this| { |
| this.structurally_instantiate_normalizes_to_term( |
| goal, |
| goal.predicate.alias, |
| ); |
| this.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| }); |
| } |
| |
| ty::Adt(def, args) if def.is_struct() => match def.struct_tail_ty(cx) { |
| None => Ty::new_unit(cx), |
| Some(tail_ty) => Ty::new_projection( |
| cx, |
| metadata_def_id, |
| [tail_ty.instantiate(cx, args).skip_norm_wip()], |
| ), |
| }, |
| ty::Adt(_, _) => Ty::new_unit(cx), |
| |
| ty::Tuple(elements) => match elements.last() { |
| None => Ty::new_unit(cx), |
| Some(tail_ty) => Ty::new_projection(cx, metadata_def_id, [tail_ty]), |
| }, |
| |
| ty::UnsafeBinder(_) => { |
| // FIXME(unsafe_binder): Figure out how to handle pointee for unsafe binders. |
| todo!() |
| } |
| |
| ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) |
| | ty::Bound(..) => panic!( |
| "unexpected self ty `{:?}` when normalizing `<T as Pointee>::Metadata`", |
| goal.predicate.self_ty() |
| ), |
| }; |
| |
| ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| { |
| ecx.instantiate_normalizes_to_term(goal, metadata_ty.into()); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| } |
| |
| fn consider_builtin_future_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let self_ty = goal.predicate.self_ty(); |
| let ty::Coroutine(def_id, args) = self_ty.kind() else { |
| return Err(NoSolution.into()); |
| }; |
| |
| // Coroutines are not futures unless they come from `async` desugaring |
| let cx = ecx.cx(); |
| if !cx.coroutine_is_async(def_id) { |
| return Err(NoSolution.into()); |
| } |
| |
| let term = args.as_coroutine().return_ty().into(); |
| |
| Self::probe_and_consider_implied_clause( |
| ecx, |
| CandidateSource::BuiltinImpl(BuiltinImplSource::Misc), |
| goal, |
| ty::ProjectionPredicate { |
| projection_term: ty::AliasTerm::new(ecx.cx(), goal.predicate.alias.kind, [self_ty]), |
| term, |
| } |
| .upcast(cx), |
| // Technically, we need to check that the future type is Sized, |
| // but that's already proven by the coroutine being WF. |
| [], |
| ) |
| } |
| |
| fn consider_builtin_iterator_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let self_ty = goal.predicate.self_ty(); |
| let ty::Coroutine(def_id, args) = self_ty.kind() else { |
| return Err(NoSolution.into()); |
| }; |
| |
| // Coroutines are not Iterators unless they come from `gen` desugaring |
| let cx = ecx.cx(); |
| if !cx.coroutine_is_gen(def_id) { |
| return Err(NoSolution.into()); |
| } |
| |
| let term = args.as_coroutine().yield_ty().into(); |
| |
| Self::probe_and_consider_implied_clause( |
| ecx, |
| CandidateSource::BuiltinImpl(BuiltinImplSource::Misc), |
| goal, |
| ty::ProjectionPredicate { |
| projection_term: ty::AliasTerm::new(ecx.cx(), goal.predicate.alias.kind, [self_ty]), |
| term, |
| } |
| .upcast(cx), |
| // Technically, we need to check that the iterator type is Sized, |
| // but that's already proven by the generator being WF. |
| [], |
| ) |
| .map_err(Into::into) |
| } |
| |
| fn consider_builtin_fused_iterator_candidate( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| panic!("`FusedIterator` does not have an associated type: {:?}", goal); |
| } |
| |
| fn consider_builtin_async_iterator_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let self_ty = goal.predicate.self_ty(); |
| let ty::Coroutine(def_id, args) = self_ty.kind() else { |
| return Err(NoSolution.into()); |
| }; |
| |
| // Coroutines are not AsyncIterators unless they come from `gen` desugaring |
| let cx = ecx.cx(); |
| if !cx.coroutine_is_async_gen(def_id) { |
| return Err(NoSolution.into()); |
| } |
| |
| ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| { |
| let expected_ty = ecx.next_ty_infer(); |
| // Take `AsyncIterator<Item = I>` and turn it into the corresponding |
| // coroutine yield ty `Poll<Option<I>>`. |
| let wrapped_expected_ty = Ty::new_adt( |
| cx, |
| cx.adt_def(cx.require_adt_lang_item(SolverAdtLangItem::Poll)), |
| cx.mk_args(&[Ty::new_adt( |
| cx, |
| cx.adt_def(cx.require_adt_lang_item(SolverAdtLangItem::Option)), |
| cx.mk_args(&[expected_ty.into()]), |
| ) |
| .into()]), |
| ); |
| let yield_ty = args.as_coroutine().yield_ty(); |
| ecx.eq(goal.param_env, wrapped_expected_ty, yield_ty)?; |
| ecx.instantiate_normalizes_to_term(goal, expected_ty.into()); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| } |
| |
| fn consider_builtin_coroutine_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let self_ty = goal.predicate.self_ty(); |
| let ty::Coroutine(def_id, args) = self_ty.kind() else { |
| return Err(NoSolution.into()); |
| }; |
| |
| // `async`-desugared coroutines do not implement the coroutine trait |
| let cx = ecx.cx(); |
| if !cx.is_general_coroutine(def_id) { |
| return Err(NoSolution.into()); |
| } |
| |
| let coroutine = args.as_coroutine(); |
| let def_id = goal.predicate.alias.expect_projection_ty_def_id(); |
| |
| let term = if cx.is_projection_lang_item(def_id, SolverProjectionLangItem::CoroutineReturn) |
| { |
| coroutine.return_ty().into() |
| } else if cx.is_projection_lang_item(def_id, SolverProjectionLangItem::CoroutineYield) { |
| coroutine.yield_ty().into() |
| } else { |
| panic!("unexpected associated item `{:?}` for `{self_ty:?}`", def_id) |
| }; |
| |
| Self::probe_and_consider_implied_clause( |
| ecx, |
| CandidateSource::BuiltinImpl(BuiltinImplSource::Misc), |
| goal, |
| ty::ProjectionPredicate { |
| projection_term: ty::AliasTerm::new( |
| ecx.cx(), |
| goal.predicate.alias.kind, |
| [self_ty, coroutine.resume_ty()], |
| ), |
| term, |
| } |
| .upcast(cx), |
| // Technically, we need to check that the coroutine type is Sized, |
| // but that's already proven by the coroutine being WF. |
| [], |
| ) |
| } |
| |
| fn consider_structural_builtin_unsize_candidates( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Vec<Candidate<I>>, RerunNonErased> { |
| panic!("`Unsize` does not have an associated type: {:?}", goal); |
| } |
| |
| fn consider_builtin_discriminant_kind_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let self_ty = goal.predicate.self_ty(); |
| let discriminant_ty = match self_ty.kind() { |
| ty::Bool |
| | ty::Char |
| | ty::Int(..) |
| | ty::Uint(..) |
| | ty::Float(..) |
| | ty::Array(..) |
| | ty::Pat(..) |
| | ty::RawPtr(..) |
| | ty::Ref(..) |
| | ty::FnDef(..) |
| | ty::FnPtr(..) |
| | ty::Closure(..) |
| | ty::CoroutineClosure(..) |
| | ty::Infer(ty::IntVar(..) | ty::FloatVar(..)) |
| | ty::Coroutine(..) |
| | ty::CoroutineWitness(..) |
| | ty::Never |
| | ty::Foreign(..) |
| | ty::Adt(_, _) |
| | ty::Str |
| | ty::Slice(_) |
| | ty::Dynamic(_, _) |
| | ty::Tuple(_) |
| | ty::Error(_) => self_ty.discriminant_ty(ecx.cx()), |
| |
| ty::UnsafeBinder(_) => { |
| // FIXME(unsafe_binders): instantiate this with placeholders?? i guess?? |
| todo!("discr subgoal...") |
| } |
| |
| // Given an alias, parameter, or placeholder we add an impl candidate normalizing to a rigid |
| // alias. In case there's a where-bound further constraining this alias it is preferred over |
| // this impl candidate anyways. It's still a bit scuffed. |
| ty::Alias(_) | ty::Param(_) | ty::Placeholder(..) => { |
| return ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| { |
| ecx.structurally_instantiate_normalizes_to_term(goal, goal.predicate.alias); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }); |
| } |
| |
| ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) |
| | ty::Bound(..) => panic!( |
| "unexpected self ty `{:?}` when normalizing `<T as DiscriminantKind>::Discriminant`", |
| goal.predicate.self_ty() |
| ), |
| }; |
| |
| ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| { |
| ecx.instantiate_normalizes_to_term(goal, discriminant_ty.into()); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| } |
| |
| fn consider_builtin_destruct_candidate( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| panic!("`Destruct` does not have an associated type: {:?}", goal); |
| } |
| |
| fn consider_builtin_transmute_candidate( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| panic!("`TransmuteFrom` does not have an associated type: {:?}", goal) |
| } |
| |
| fn consider_builtin_bikeshed_guaranteed_no_drop_candidate( |
| _ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| unreachable!("`BikeshedGuaranteedNoDrop` does not have an associated type: {:?}", goal) |
| } |
| |
| fn consider_builtin_field_candidate( |
| ecx: &mut EvalCtxt<'_, D>, |
| goal: Goal<I, Self>, |
| ) -> Result<Candidate<I>, NoSolutionOrRerunNonErased> { |
| let self_ty = goal.predicate.self_ty(); |
| let ty::Adt(def, args) = self_ty.kind() else { |
| return Err(NoSolution.into()); |
| }; |
| let Some(FieldInfo { base, ty, .. }) = def.field_representing_type_info(ecx.cx(), args) |
| else { |
| return Err(NoSolution.into()); |
| }; |
| let def_id = goal.predicate.alias.expect_projection_ty_def_id(); |
| let ty = match ecx.cx().as_projection_lang_item(def_id) { |
| Some(SolverProjectionLangItem::FieldBase) => base, |
| Some(SolverProjectionLangItem::FieldType) => ty, |
| _ => panic!("unexpected associated type {:?} in `Field`", goal.predicate), |
| }; |
| ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| { |
| ecx.instantiate_normalizes_to_term(goal, ty.into()); |
| ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) |
| }) |
| } |
| } |
| |
| impl<D, I> EvalCtxt<'_, D> |
| where |
| D: SolverDelegate<Interner = I>, |
| I: Interner, |
| { |
| fn translate_args( |
| &mut self, |
| goal: Goal<I, ty::NormalizesTo<I>>, |
| impl_def_id: I::ImplId, |
| impl_args: I::GenericArgs, |
| impl_trait_ref: rustc_type_ir::TraitRef<I>, |
| target_container_def_id: I::DefId, |
| ) -> Result<I::GenericArgs, NoSolution> { |
| let cx = self.cx(); |
| Ok(if target_container_def_id == impl_trait_ref.def_id.into() { |
| // Default value from the trait definition. No need to rebase. |
| goal.predicate.alias.args |
| } else if target_container_def_id == impl_def_id.into() { |
| // Same impl, no need to fully translate, just a rebase from |
| // the trait is sufficient. |
| goal.predicate.alias.args.rebase_onto(cx, impl_trait_ref.def_id.into(), impl_args) |
| } else { |
| let target_args = self.fresh_args_for_item(target_container_def_id); |
| let target_trait_ref = cx |
| .impl_trait_ref(target_container_def_id.try_into().unwrap()) |
| .instantiate(cx, target_args) |
| .skip_norm_wip(); |
| // Relate source impl to target impl by equating trait refs. |
| self.eq(goal.param_env, impl_trait_ref, target_trait_ref)?; |
| // Also add predicates since they may be needed to constrain the |
| // target impl's params. |
| self.add_goals( |
| GoalSource::Misc, |
| cx.predicates_of(target_container_def_id) |
| .iter_instantiated(cx, target_args) |
| .map(Unnormalized::skip_norm_wip) |
| .map(|pred| goal.with(cx, pred)), |
| ); |
| goal.predicate.alias.args.rebase_onto(cx, impl_trait_ref.def_id.into(), target_args) |
| }) |
| } |
| } |
