diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs index b18b59d9a75..f18f1f4f8f0 100644 --- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs +++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs @@ -12,7 +12,6 @@ use rustc_middle::traits::solve::{ inspect, CanonicalInput, CanonicalResponse, Certainty, PredefinedOpaquesData, QueryResult, }; -use rustc_middle::traits::specialization_graph; use rustc_middle::ty::AliasRelationDirection; use rustc_middle::ty::TypeFolder; use rustc_middle::ty::{ @@ -900,16 +899,6 @@ pub(super) fn fresh_args_for_item(&mut self, def_id: DefId) -> ty::GenericArgsRe args } - pub(super) fn translate_args( - &self, - param_env: ty::ParamEnv<'tcx>, - source_impl: DefId, - source_args: ty::GenericArgsRef<'tcx>, - target_node: specialization_graph::Node, - ) -> ty::GenericArgsRef<'tcx> { - crate::traits::translate_args(self.infcx, param_env, source_impl, source_args, target_node) - } - pub(super) fn register_ty_outlives(&self, ty: Ty<'tcx>, lt: ty::Region<'tcx>) { self.infcx.register_region_obligation_with_cause(ty, lt, &ObligationCause::dummy()); } diff --git a/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs b/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs index 22a77e2ecb8..8c63bd824bc 100644 --- a/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs +++ b/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs @@ -1,4 +1,4 @@ -use crate::traits::specialization_graph; +use crate::traits::specialization_graph::{self, LeafDef, Node}; use super::assembly::structural_traits::AsyncCallableRelevantTypes; use super::assembly::{self, structural_traits, Candidate}; @@ -9,7 +9,6 @@ use rustc_infer::traits::query::NoSolution; use rustc_infer::traits::solve::inspect::ProbeKind; use rustc_infer::traits::solve::MaybeCause; -use rustc_infer::traits::specialization_graph::LeafDef; use rustc_infer::traits::Reveal; use rustc_middle::traits::solve::{CandidateSource, Certainty, Goal, QueryResult}; use rustc_middle::traits::BuiltinImplSource; @@ -189,8 +188,7 @@ fn consider_impl_candidate( // 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, + let Some(assoc_def) = ecx.fetch_eligible_assoc_item_def( goal.param_env, goal_trait_ref, goal.predicate.def_id(), @@ -235,16 +233,10 @@ fn consider_impl_candidate( // // And then map these args to the args of the defining impl of `Assoc`, going // from `[u32, u64]` to `[u32, i32, u64]`. - let impl_args_with_gat = - goal.predicate.alias.args.rebase_onto(tcx, goal_trait_ref.def_id, impl_args); - let args = ecx.translate_args( - goal.param_env, - impl_def_id, - impl_args_with_gat, - assoc_def.defining_node, - ); + let associated_item_args = + ecx.translate_args(&assoc_def, goal, impl_def_id, impl_args, impl_trait_ref)?; - if !tcx.check_args_compatible(assoc_def.item.def_id, args) { + if !tcx.check_args_compatible(assoc_def.item.def_id, associated_item_args) { return error_response( ecx, "associated item has mismatched generic item arguments", @@ -272,7 +264,7 @@ fn consider_impl_candidate( ty::AssocKind::Fn => unreachable!("we should never project to a fn"), }; - ecx.instantiate_normalizes_to_term(goal, term.instantiate(tcx, args)); + ecx.instantiate_normalizes_to_term(goal, term.instantiate(tcx, associated_item_args)); ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) }) } @@ -889,38 +881,79 @@ fn consider_builtin_transmute_candidate( } } -/// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code. -/// -/// FIXME: We should merge these 3 implementations as it's likely that they otherwise -/// diverge. -#[instrument(level = "trace", skip(ecx, param_env), ret)] -fn fetch_eligible_assoc_item_def<'tcx>( - ecx: &EvalCtxt<'_, InferCtxt<'tcx>>, - param_env: ty::ParamEnv<'tcx>, - goal_trait_ref: ty::TraitRef<'tcx>, - trait_assoc_def_id: DefId, - impl_def_id: DefId, -) -> Result, NoSolution> { - let node_item = - specialization_graph::assoc_def(ecx.interner(), impl_def_id, trait_assoc_def_id) - .map_err(|ErrorGuaranteed { .. }| NoSolution)?; +impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> { + fn translate_args( + &mut self, + assoc_def: &LeafDef, + goal: Goal<'tcx, ty::NormalizesTo<'tcx>>, + impl_def_id: DefId, + impl_args: ty::GenericArgsRef<'tcx>, + impl_trait_ref: rustc_type_ir::TraitRef>, + ) -> Result, NoSolution> { + let tcx = self.interner(); + Ok(match assoc_def.defining_node { + Node::Trait(_) => goal.predicate.alias.args, + Node::Impl(target_impl_def_id) => { + if target_impl_def_id == impl_def_id { + // Same impl, no need to fully translate, just a rebase from + // the trait is sufficient. + goal.predicate.alias.args.rebase_onto(tcx, impl_trait_ref.def_id, impl_args) + } else { + let target_args = self.fresh_args_for_item(target_impl_def_id); + let target_trait_ref = tcx + .impl_trait_ref(target_impl_def_id) + .unwrap() + .instantiate(tcx, target_args); + // 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, + tcx.predicates_of(target_impl_def_id) + .instantiate(tcx, target_args) + .into_iter() + .map(|(pred, _)| goal.with(tcx, pred)), + ); + goal.predicate.alias.args.rebase_onto(tcx, impl_trait_ref.def_id, target_args) + } + } + }) + } - let eligible = if node_item.is_final() { - // Non-specializable items are always projectable. - true - } else { - // Only reveal a specializable default if we're past type-checking - // and the obligation is monomorphic, otherwise passes such as - // transmute checking and polymorphic MIR optimizations could - // get a result which isn't correct for all monomorphizations. - if param_env.reveal() == Reveal::All { - let poly_trait_ref = ecx.resolve_vars_if_possible(goal_trait_ref); - !poly_trait_ref.still_further_specializable() + /// This behavior is also implemented in `rustc_ty_utils` and in the old `project` code. + /// + /// FIXME: We should merge these 3 implementations as it's likely that they otherwise + /// diverge. + #[instrument(level = "trace", skip(self, param_env), ret)] + fn fetch_eligible_assoc_item_def( + &self, + param_env: ty::ParamEnv<'tcx>, + goal_trait_ref: ty::TraitRef<'tcx>, + trait_assoc_def_id: DefId, + impl_def_id: DefId, + ) -> Result, NoSolution> { + let node_item = + specialization_graph::assoc_def(self.interner(), impl_def_id, trait_assoc_def_id) + .map_err(|ErrorGuaranteed { .. }| NoSolution)?; + + let eligible = if node_item.is_final() { + // Non-specializable items are always projectable. + true } else { - trace!(?node_item.item.def_id, "not eligible due to default"); - false - } - }; + // Only reveal a specializable default if we're past type-checking + // and the obligation is monomorphic, otherwise passes such as + // transmute checking and polymorphic MIR optimizations could + // get a result which isn't correct for all monomorphizations. + if param_env.reveal() == Reveal::All { + let poly_trait_ref = self.resolve_vars_if_possible(goal_trait_ref); + !poly_trait_ref.still_further_specializable() + } else { + trace!(?node_item.item.def_id, "not eligible due to default"); + false + } + }; - if eligible { Ok(Some(node_item)) } else { Ok(None) } + if eligible { Ok(Some(node_item)) } else { Ok(None) } + } } diff --git a/tests/ui/specialization/source-impl-requires-constraining-predicates-ambig.next.stderr b/tests/ui/specialization/source-impl-requires-constraining-predicates-ambig.next.stderr new file mode 100644 index 00000000000..17918a77821 --- /dev/null +++ b/tests/ui/specialization/source-impl-requires-constraining-predicates-ambig.next.stderr @@ -0,0 +1,12 @@ +warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes + --> $DIR/source-impl-requires-constraining-predicates-ambig.rs:14:12 + | +LL | #![feature(specialization)] + | ^^^^^^^^^^^^^^ + | + = note: see issue #31844 for more information + = help: consider using `min_specialization` instead, which is more stable and complete + = note: `#[warn(incomplete_features)]` on by default + +warning: 1 warning emitted + diff --git a/tests/ui/specialization/source-impl-requires-constraining-predicates-ambig.rs b/tests/ui/specialization/source-impl-requires-constraining-predicates-ambig.rs new file mode 100644 index 00000000000..977493c885b --- /dev/null +++ b/tests/ui/specialization/source-impl-requires-constraining-predicates-ambig.rs @@ -0,0 +1,29 @@ +//@ revisions: current next +//@ ignore-compare-mode-next-solver (explicit revisions) +//@[next] compile-flags: -Znext-solver +//@[next] check-pass +//@[current] known-bug: unknown +//@[current] failure-status: 101 +//@[current] dont-check-compiler-stderr + +// Tests that rebasing from the concrete impl to the default impl also processes the +// `[u32; 0]: IntoIterator` predicate to constrain the `?U` impl arg. +// This test also makes sure that we don't do anything weird when rebasing the args +// is ambiguous. + +#![feature(specialization)] +//[next]~^ WARN the feature `specialization` is incomplete + +trait Spec { + type Assoc; +} + +default impl Spec for T where T: IntoIterator { + type Assoc = U; +} + +impl Spec for [T; 0] {} + +fn main() { + let x: <[_; 0] as Spec>::Assoc = 1; +} diff --git a/tests/ui/specialization/source-impl-requires-constraining-predicates.current.stderr b/tests/ui/specialization/source-impl-requires-constraining-predicates.current.stderr new file mode 100644 index 00000000000..3442e5b5ca6 --- /dev/null +++ b/tests/ui/specialization/source-impl-requires-constraining-predicates.current.stderr @@ -0,0 +1,12 @@ +warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes + --> $DIR/source-impl-requires-constraining-predicates.rs:9:12 + | +LL | #![feature(specialization)] + | ^^^^^^^^^^^^^^ + | + = note: see issue #31844 for more information + = help: consider using `min_specialization` instead, which is more stable and complete + = note: `#[warn(incomplete_features)]` on by default + +warning: 1 warning emitted + diff --git a/tests/ui/specialization/source-impl-requires-constraining-predicates.next.stderr b/tests/ui/specialization/source-impl-requires-constraining-predicates.next.stderr new file mode 100644 index 00000000000..3442e5b5ca6 --- /dev/null +++ b/tests/ui/specialization/source-impl-requires-constraining-predicates.next.stderr @@ -0,0 +1,12 @@ +warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes + --> $DIR/source-impl-requires-constraining-predicates.rs:9:12 + | +LL | #![feature(specialization)] + | ^^^^^^^^^^^^^^ + | + = note: see issue #31844 for more information + = help: consider using `min_specialization` instead, which is more stable and complete + = note: `#[warn(incomplete_features)]` on by default + +warning: 1 warning emitted + diff --git a/tests/ui/specialization/source-impl-requires-constraining-predicates.rs b/tests/ui/specialization/source-impl-requires-constraining-predicates.rs new file mode 100644 index 00000000000..532fc367640 --- /dev/null +++ b/tests/ui/specialization/source-impl-requires-constraining-predicates.rs @@ -0,0 +1,24 @@ +//@ check-pass +//@ revisions: current next +//@ ignore-compare-mode-next-solver (explicit revisions) +//@[next] compile-flags: -Znext-solver + +// Tests that rebasing from the concrete impl to the default impl also processes the +// `[u32; 0]: IntoIterator` predicate to constrain the `?U` impl arg. + +#![feature(specialization)] +//~^ WARN the feature `specialization` is incomplete + +trait Spec { + type Assoc; +} + +default impl Spec for T where T: IntoIterator { + type Assoc = U; +} + +impl Spec for [T; 0] {} + +fn main() { + let x: <[u32; 0] as Spec>::Assoc = 1; +}