diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/solve/project_goals.rs')
| -rw-r--r-- | compiler/rustc_trait_selection/src/solve/project_goals.rs | 157 |
1 files changed, 78 insertions, 79 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs index e53b784a756..9b701ca2023 100644 --- a/compiler/rustc_trait_selection/src/solve/project_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs @@ -146,89 +146,88 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { return Err(NoSolution); } - ecx.probe( - |r| CandidateKind::Candidate { name: "impl".into(), result: *r }).enter( - |ecx| { - let impl_substs = ecx.fresh_substs_for_item(impl_def_id); - let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs); - - ecx.eq(goal.param_env, goal_trait_ref, impl_trait_ref)?; - - let where_clause_bounds = tcx - .predicates_of(impl_def_id) - .instantiate(tcx, impl_substs) - .predicates - .into_iter() - .map(|pred| goal.with(tcx, pred)); - ecx.add_goals(where_clause_bounds); - - // In case the associated item is hidden due to specialization, we have to - // return ambiguity this would otherwise be incomplete, resulting in - // unsoundness during coherence (#105782). - let Some(assoc_def) = fetch_eligible_assoc_item_def( - ecx, - goal.param_env, - goal_trait_ref, - goal.predicate.def_id(), - impl_def_id - )? else { - return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS); - }; - - if !assoc_def.item.defaultness(tcx).has_value() { - let guar = tcx.sess.delay_span_bug( - tcx.def_span(assoc_def.item.def_id), - "missing value for assoc item in impl", - ); - let error_term = match assoc_def.item.kind { - ty::AssocKind::Const => ty::Const::new_error(tcx, - guar, - tcx.type_of(goal.predicate.def_id()) - .subst(tcx, goal.predicate.projection_ty.substs), - ) - .into(), - ty::AssocKind::Type => Ty::new_error(tcx,guar).into(), - ty::AssocKind::Fn => unreachable!(), - }; - ecx.eq(goal.param_env, goal.predicate.term, error_term) - .expect("expected goal term to be fully unconstrained"); - return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes); - } + ecx.probe(|r| CandidateKind::Candidate { name: "impl".into(), result: *r }).enter(|ecx| { + let impl_substs = ecx.fresh_substs_for_item(impl_def_id); + let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs); + + ecx.eq(goal.param_env, goal_trait_ref, impl_trait_ref)?; + + let where_clause_bounds = tcx + .predicates_of(impl_def_id) + .instantiate(tcx, impl_substs) + .predicates + .into_iter() + .map(|pred| goal.with(tcx, pred)); + ecx.add_goals(where_clause_bounds); + + // In case the associated item is hidden due to specialization, we have to + // return ambiguity this would otherwise be incomplete, resulting in + // unsoundness during coherence (#105782). + let Some(assoc_def) = fetch_eligible_assoc_item_def( + ecx, + goal.param_env, + goal_trait_ref, + goal.predicate.def_id(), + impl_def_id, + )? + else { + return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS); + }; - // Getting the right substitutions 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 substs onto the impl, going from `[Vec<u32>, i32, u64]` - // to `[u32, u64]`. - // - // And then map these substs to the substs of the defining impl of `Assoc`, going - // from `[u32, u64]` to `[u32, i32, u64]`. - let impl_substs_with_gat = goal.predicate.projection_ty.substs.rebase_onto( - tcx, - goal_trait_ref.def_id, - impl_substs, - ); - let substs = ecx.translate_substs( - goal.param_env, - impl_def_id, - impl_substs_with_gat, - assoc_def.defining_node, + if !assoc_def.item.defaultness(tcx).has_value() { + let guar = tcx.sess.delay_span_bug( + tcx.def_span(assoc_def.item.def_id), + "missing value for assoc item in impl", ); - - // Finally we construct the actual value of the associated type. - let term = match assoc_def.item.kind { - ty::AssocKind::Type => tcx.type_of(assoc_def.item.def_id).map_bound(|ty| ty.into()), - ty::AssocKind::Const => bug!("associated const projection is not supported yet"), - ty::AssocKind::Fn => unreachable!("we should never project to a fn"), + let error_term = match assoc_def.item.kind { + ty::AssocKind::Const => ty::Const::new_error( + tcx, + guar, + tcx.type_of(goal.predicate.def_id()) + .subst(tcx, goal.predicate.projection_ty.substs), + ) + .into(), + ty::AssocKind::Type => Ty::new_error(tcx, guar).into(), + ty::AssocKind::Fn => unreachable!(), }; - - ecx.eq(goal.param_env, goal.predicate.term, term.subst(tcx, substs)) + ecx.eq(goal.param_env, goal.predicate.term, error_term) .expect("expected goal term to be fully unconstrained"); - ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) - }, - ) + return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes); + } + + // Getting the right substitutions 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 substs onto the impl, going from `[Vec<u32>, i32, u64]` + // to `[u32, u64]`. + // + // And then map these substs to the substs of the defining impl of `Assoc`, going + // from `[u32, u64]` to `[u32, i32, u64]`. + let impl_substs_with_gat = goal.predicate.projection_ty.substs.rebase_onto( + tcx, + goal_trait_ref.def_id, + impl_substs, + ); + let substs = ecx.translate_substs( + goal.param_env, + impl_def_id, + impl_substs_with_gat, + assoc_def.defining_node, + ); + + // Finally we construct the actual value of the associated type. + let term = match assoc_def.item.kind { + ty::AssocKind::Type => tcx.type_of(assoc_def.item.def_id).map_bound(|ty| ty.into()), + ty::AssocKind::Const => bug!("associated const projection is not supported yet"), + ty::AssocKind::Fn => unreachable!("we should never project to a fn"), + }; + + ecx.eq(goal.param_env, goal.predicate.term, term.subst(tcx, substs)) + .expect("expected goal term to be fully unconstrained"); + ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) + }) } fn consider_auto_trait_candidate( |