diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src')
4 files changed, 99 insertions, 135 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/assembly.rs b/compiler/rustc_trait_selection/src/solve/assembly.rs index 8525b96c0c2..775974d8e9a 100644 --- a/compiler/rustc_trait_selection/src/solve/assembly.rs +++ b/compiler/rustc_trait_selection/src/solve/assembly.rs @@ -3,7 +3,7 @@ use super::infcx_ext::InferCtxtExt; #[cfg(doc)] use super::trait_goals::structural_traits::*; -use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, QueryResult}; +use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, MaybeCause, QueryResult}; use rustc_hir::def_id::DefId; use rustc_infer::traits::query::NoSolution; use rustc_infer::traits::util::elaborate_predicates; @@ -399,10 +399,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { ty::Alias(_, alias_ty) => alias_ty, }; - for (assumption, _) in self - .tcx() - .bound_explicit_item_bounds(alias_ty.def_id) - .subst_iter_copied(self.tcx(), alias_ty.substs) + for assumption in self.tcx().item_bounds(alias_ty.def_id).subst(self.tcx(), alias_ty.substs) { match G::consider_assumption(self, goal, assumption) { Ok(result) => { @@ -462,4 +459,78 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { } } } + + #[instrument(level = "debug", skip(self), ret)] + pub(super) fn merge_candidates_and_discard_reservation_impls( + &mut self, + mut candidates: Vec<Candidate<'tcx>>, + ) -> QueryResult<'tcx> { + match candidates.len() { + 0 => return Err(NoSolution), + 1 => return Ok(self.discard_reservation_impl(candidates.pop().unwrap()).result), + _ => {} + } + + if candidates.len() > 1 { + let mut i = 0; + 'outer: while i < candidates.len() { + for j in (0..candidates.len()).filter(|&j| i != j) { + if self.trait_candidate_should_be_dropped_in_favor_of( + &candidates[i], + &candidates[j], + ) { + debug!(candidate = ?candidates[i], "Dropping candidate #{}/{}", i, candidates.len()); + candidates.swap_remove(i); + continue 'outer; + } + } + + debug!(candidate = ?candidates[i], "Retaining candidate #{}/{}", i, candidates.len()); + i += 1; + } + + // If there are *STILL* multiple candidates, give up + // and report ambiguity. + if candidates.len() > 1 { + let certainty = if candidates.iter().all(|x| { + matches!(x.result.value.certainty, Certainty::Maybe(MaybeCause::Overflow)) + }) { + Certainty::Maybe(MaybeCause::Overflow) + } else { + Certainty::AMBIGUOUS + }; + return self.make_canonical_response(certainty); + } + } + + Ok(self.discard_reservation_impl(candidates.pop().unwrap()).result) + } + + fn trait_candidate_should_be_dropped_in_favor_of( + &self, + candidate: &Candidate<'tcx>, + other: &Candidate<'tcx>, + ) -> bool { + // FIXME: implement this + match (candidate.source, other.source) { + (CandidateSource::Impl(_), _) + | (CandidateSource::ParamEnv(_), _) + | (CandidateSource::AliasBound, _) + | (CandidateSource::BuiltinImpl, _) => false, + } + } + + fn discard_reservation_impl(&self, mut candidate: Candidate<'tcx>) -> Candidate<'tcx> { + if let CandidateSource::Impl(def_id) = candidate.source { + if let ty::ImplPolarity::Reservation = self.tcx().impl_polarity(def_id) { + debug!("Selected reservation impl"); + // We assemble all candidates inside of a probe so by + // making a new canonical response here our result will + // have no constraints. + candidate.result = self.make_canonical_response(Certainty::AMBIGUOUS).unwrap(); + } + } + + candidate + } } diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs index e3ec71d1b4f..4fea49893a6 100644 --- a/compiler/rustc_trait_selection/src/solve/project_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs @@ -1,6 +1,6 @@ use crate::traits::{specialization_graph, translate_substs}; -use super::assembly::{self, Candidate, CandidateSource}; +use super::assembly; use super::infcx_ext::InferCtxtExt; use super::trait_goals::structural_traits; use super::{Certainty, EvalCtxt, Goal, QueryResult}; @@ -34,7 +34,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { // projection cache in the solver. if self.term_is_fully_unconstrained(goal) { let candidates = self.assemble_and_evaluate_candidates(goal); - self.merge_project_candidates(candidates) + self.merge_candidates_and_discard_reservation_impls(candidates) } else { let predicate = goal.predicate; let unconstrained_rhs = match predicate.term.unpack() { @@ -153,59 +153,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { self.make_canonical_response(normalization_certainty.unify_and(rhs_certainty)) } - - fn merge_project_candidates( - &mut self, - mut candidates: Vec<Candidate<'tcx>>, - ) -> QueryResult<'tcx> { - match candidates.len() { - 0 => return Err(NoSolution), - 1 => return Ok(candidates.pop().unwrap().result), - _ => {} - } - - if candidates.len() > 1 { - let mut i = 0; - 'outer: while i < candidates.len() { - for j in (0..candidates.len()).filter(|&j| i != j) { - if self.project_candidate_should_be_dropped_in_favor_of( - &candidates[i], - &candidates[j], - ) { - debug!(candidate = ?candidates[i], "Dropping candidate #{}/{}", i, candidates.len()); - candidates.swap_remove(i); - continue 'outer; - } - } - - debug!(candidate = ?candidates[i], "Retaining candidate #{}/{}", i, candidates.len()); - // If there are *STILL* multiple candidates, give up - // and report ambiguity. - i += 1; - if i > 1 { - debug!("multiple matches, ambig"); - // FIXME: return overflow if all candidates overflow, otherwise return ambiguity. - unimplemented!(); - } - } - } - - Ok(candidates.pop().unwrap().result) - } - - fn project_candidate_should_be_dropped_in_favor_of( - &self, - candidate: &Candidate<'tcx>, - other: &Candidate<'tcx>, - ) -> bool { - // FIXME: implement this - match (candidate.source, other.source) { - (CandidateSource::Impl(_), _) - | (CandidateSource::ParamEnv(_), _) - | (CandidateSource::BuiltinImpl, _) - | (CandidateSource::AliasBound, _) => unimplemented!(), - } - } } impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { @@ -452,7 +399,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { [ty::GenericArg::from(goal.predicate.self_ty())], )); - let is_sized_certainty = ecx.evaluate_goal(goal.with(tcx, sized_predicate))?.1; + let (_, is_sized_certainty) = + ecx.evaluate_goal(goal.with(tcx, sized_predicate))?; return ecx.eq_term_and_make_canonical_response( goal, is_sized_certainty, diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs index 06a72e95d49..6554c739b3f 100644 --- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs @@ -2,7 +2,7 @@ use std::iter; -use super::assembly::{self, Candidate, CandidateSource}; +use super::assembly; use super::infcx_ext::InferCtxtExt; use super::{CanonicalResponse, Certainty, EvalCtxt, Goal, QueryResult}; use rustc_hir::def_id::DefId; @@ -89,6 +89,20 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> { ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, Self>, ) -> QueryResult<'tcx> { + // This differs from the current stable behavior and + // fixes #84857. Due to breakage found via crater, we + // currently instead lint patterns which can be used to + // exploit this unsoundness on stable, see #93367 for + // more details. + if let Some(def_id) = ecx.tcx().find_map_relevant_impl( + goal.predicate.def_id(), + goal.predicate.self_ty(), + Some, + ) { + debug!(?def_id, ?goal, "disqualified auto-trait implementation"); + return Err(NoSolution); + } + ecx.probe_and_evaluate_goal_for_constituent_tys( goal, structural_traits::instantiate_constituent_tys_for_auto_trait, @@ -479,73 +493,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { goal: Goal<'tcx, TraitPredicate<'tcx>>, ) -> QueryResult<'tcx> { let candidates = self.assemble_and_evaluate_candidates(goal); - self.merge_trait_candidates_discard_reservation_impls(candidates) - } - - #[instrument(level = "debug", skip(self), ret)] - pub(super) fn merge_trait_candidates_discard_reservation_impls( - &mut self, - mut candidates: Vec<Candidate<'tcx>>, - ) -> QueryResult<'tcx> { - match candidates.len() { - 0 => return Err(NoSolution), - 1 => return Ok(self.discard_reservation_impl(candidates.pop().unwrap()).result), - _ => {} - } - - if candidates.len() > 1 { - let mut i = 0; - 'outer: while i < candidates.len() { - for j in (0..candidates.len()).filter(|&j| i != j) { - if self.trait_candidate_should_be_dropped_in_favor_of( - &candidates[i], - &candidates[j], - ) { - debug!(candidate = ?candidates[i], "Dropping candidate #{}/{}", i, candidates.len()); - candidates.swap_remove(i); - continue 'outer; - } - } - - debug!(candidate = ?candidates[i], "Retaining candidate #{}/{}", i, candidates.len()); - // If there are *STILL* multiple candidates, give up - // and report ambiguity. - i += 1; - if i > 1 { - debug!("multiple matches, ambig"); - // FIXME: return overflow if all candidates overflow, otherwise return ambiguity. - unimplemented!(); - } - } - } - - Ok(self.discard_reservation_impl(candidates.pop().unwrap()).result) - } - - fn trait_candidate_should_be_dropped_in_favor_of( - &self, - candidate: &Candidate<'tcx>, - other: &Candidate<'tcx>, - ) -> bool { - // FIXME: implement this - match (candidate.source, other.source) { - (CandidateSource::Impl(_), _) - | (CandidateSource::ParamEnv(_), _) - | (CandidateSource::AliasBound, _) - | (CandidateSource::BuiltinImpl, _) => unimplemented!(), - } - } - - fn discard_reservation_impl(&self, candidate: Candidate<'tcx>) -> Candidate<'tcx> { - if let CandidateSource::Impl(def_id) = candidate.source { - if let ty::ImplPolarity::Reservation = self.tcx().impl_polarity(def_id) { - debug!("Selected reservation impl"); - // FIXME: reduce candidate to ambiguous - // FIXME: replace `var_values` with identity, yeet external constraints. - unimplemented!() - } - } - - candidate + self.merge_candidates_and_discard_reservation_impls(candidates) } } diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs index 8f548acfd2e..bafa2981a87 100644 --- a/compiler/rustc_trait_selection/src/traits/object_safety.rs +++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs @@ -646,11 +646,9 @@ fn object_ty_for_trait<'tcx>( debug!(?obligation); let pred = obligation.predicate.to_opt_poly_projection_pred()?; Some(pred.map_bound(|p| { - ty::ExistentialPredicate::Projection(ty::ExistentialProjection { - def_id: p.projection_ty.def_id, - substs: p.projection_ty.substs, - term: p.term, - }) + ty::ExistentialPredicate::Projection(ty::ExistentialProjection::erase_self_ty( + tcx, p, + )) })) }) .collect(); |