From 4fb097a5de14399b86dda519e1e597104a15b3b2 Mon Sep 17 00:00:00 2001 From: Michael Goulet Date: Thu, 26 Sep 2024 23:20:59 -0400 Subject: [PATCH] Instantiate binders when checking supertrait upcasting --- compiler/rustc_infer/src/infer/at.rs | 19 +++- .../src/solve/eval_ctxt/mod.rs | 16 ++-- .../src/solve/trait_goals.rs | 49 ++++++---- .../src/traits/select/mod.rs | 96 +++++++++++++++---- 4 files changed, 132 insertions(+), 48 deletions(-) diff --git a/compiler/rustc_infer/src/infer/at.rs b/compiler/rustc_infer/src/infer/at.rs index 9f6a1763866..37f7f04db3f 100644 --- a/compiler/rustc_infer/src/infer/at.rs +++ b/compiler/rustc_infer/src/infer/at.rs @@ -159,7 +159,24 @@ pub fn eq( ToTrace::to_trace(self.cause, true, expected, actual), self.param_env, define_opaque_types, - ); + ToTrace::to_trace(self.cause, expected, actual), + expected, + actual, + ) + } + + /// Makes `expected == actual`. + pub fn eq_trace( + self, + define_opaque_types: DefineOpaqueTypes, + trace: TypeTrace<'tcx>, + expected: T, + actual: T, + ) -> InferResult<'tcx, ()> + where + T: Relate>, + { + let mut fields = CombineFields::new(self.infcx, trace, self.param_env, define_opaque_types); fields.equate(StructurallyRelateAliases::No).relate(expected, actual)?; Ok(InferOk { value: (), diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs index 12ad0724b5c..932875b759f 100644 --- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs +++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs @@ -448,10 +448,10 @@ fn compute_goal(&mut self, goal: Goal) -> QueryResult { } } } else { - self.delegate.enter_forall(kind, |kind| { - let goal = goal.with(self.cx(), ty::Binder::dummy(kind)); - self.add_goal(GoalSource::InstantiateHigherRanked, goal); - self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) + self.enter_forall(kind, |ecx, kind| { + let goal = goal.with(ecx.cx(), ty::Binder::dummy(kind)); + ecx.add_goal(GoalSource::InstantiateHigherRanked, goal); + ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) }) } } @@ -840,12 +840,14 @@ pub(super) fn instantiate_binder_with_infer + Copy>( self.delegate.instantiate_binder_with_infer(value) } + /// `enter_forall`, but takes `&mut self` and passes it back through the + /// callback since it can't be aliased during the call. pub(super) fn enter_forall + Copy, U>( - &self, + &mut self, value: ty::Binder, - f: impl FnOnce(T) -> U, + f: impl FnOnce(&mut Self, T) -> U, ) -> U { - self.delegate.enter_forall(value, f) + self.delegate.enter_forall(value, |value| f(self, value)) } pub(super) fn resolve_vars_if_possible(&self, value: T) -> T diff --git a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs index 0befe7f5e8a..493bbf1e665 100644 --- a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs +++ b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs @@ -895,10 +895,13 @@ fn consider_builtin_upcast_to_principal( source_projection.item_def_id() == target_projection.item_def_id() && ecx .probe(|_| ProbeKind::UpcastProjectionCompatibility) - .enter(|ecx| -> Result<(), NoSolution> { - ecx.sub(param_env, source_projection, target_projection)?; - let _ = ecx.try_evaluate_added_goals()?; - Ok(()) + .enter(|ecx| -> Result<_, NoSolution> { + ecx.enter_forall(target_projection, |ecx, target_projection| { + let source_projection = + ecx.instantiate_binder_with_infer(source_projection); + ecx.eq(param_env, source_projection, target_projection)?; + ecx.try_evaluate_added_goals() + }) }) .is_ok() }; @@ -909,11 +912,14 @@ fn consider_builtin_upcast_to_principal( // Check that a's supertrait (upcast_principal) is compatible // with the target (b_ty). ty::ExistentialPredicate::Trait(target_principal) => { - ecx.sub( - param_env, - upcast_principal.unwrap(), - bound.rebind(target_principal), - )?; + let source_principal = upcast_principal.unwrap(); + let target_principal = bound.rebind(target_principal); + ecx.enter_forall(target_principal, |ecx, target_principal| { + let source_principal = + ecx.instantiate_binder_with_infer(source_principal); + ecx.eq(param_env, source_principal, target_principal)?; + ecx.try_evaluate_added_goals() + })?; } // Check that b_ty's projection is satisfied by exactly one of // a_ty's projections. First, we look through the list to see if @@ -934,7 +940,12 @@ fn consider_builtin_upcast_to_principal( Certainty::AMBIGUOUS, ); } - ecx.sub(param_env, source_projection, target_projection)?; + ecx.enter_forall(target_projection, |ecx, target_projection| { + let source_projection = + ecx.instantiate_binder_with_infer(source_projection); + ecx.eq(param_env, source_projection, target_projection)?; + ecx.try_evaluate_added_goals() + })?; } // Check that b_ty's auto traits are present in a_ty's bounds. ty::ExistentialPredicate::AutoTrait(def_id) => { @@ -1187,17 +1198,15 @@ fn probe_and_evaluate_goal_for_constituent_tys( ) -> Result>, NoSolution>, ) -> Result, NoSolution> { self.probe_trait_candidate(source).enter(|ecx| { - ecx.add_goals( - GoalSource::ImplWhereBound, - constituent_tys(ecx, goal.predicate.self_ty())? - .into_iter() - .map(|ty| { - ecx.enter_forall(ty, |ty| { - goal.with(ecx.cx(), goal.predicate.with_self_ty(ecx.cx(), ty)) - }) + let goals = constituent_tys(ecx, goal.predicate.self_ty())? + .into_iter() + .map(|ty| { + ecx.enter_forall(ty, |ecx, ty| { + goal.with(ecx.cx(), goal.predicate.with_self_ty(ecx.cx(), ty)) }) - .collect::>(), - ); + }) + .collect::>(); + ecx.add_goals(GoalSource::ImplWhereBound, goals); ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) }) } diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index 2922a4898e9..c3042ab9636 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -16,6 +16,7 @@ use rustc_hir::def_id::DefId; use rustc_infer::infer::BoundRegionConversionTime::{self, HigherRankedType}; use rustc_infer::infer::DefineOpaqueTypes; +use rustc_infer::infer::at::ToTrace; use rustc_infer::infer::relate::TypeRelation; use rustc_infer::traits::TraitObligation; use rustc_middle::bug; @@ -44,7 +45,7 @@ TraitQueryMode, const_evaluatable, project, util, wf, }; use crate::error_reporting::InferCtxtErrorExt; -use crate::infer::{InferCtxt, InferCtxtExt, InferOk, TypeFreshener}; +use crate::infer::{InferCtxt, InferOk, TypeFreshener}; use crate::solve::InferCtxtSelectExt as _; use crate::traits::normalize::{normalize_with_depth, normalize_with_depth_to}; use crate::traits::project::{ProjectAndUnifyResult, ProjectionCacheKeyExt}; @@ -2579,16 +2580,32 @@ fn match_upcast_principal( // Check that a_ty's supertrait (upcast_principal) is compatible // with the target (b_ty). ty::ExistentialPredicate::Trait(target_principal) => { + let hr_source_principal = upcast_principal.map_bound(|trait_ref| { + ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref) + }); + let hr_target_principal = bound.rebind(target_principal); + nested.extend( self.infcx - .at(&obligation.cause, obligation.param_env) - .sup( - DefineOpaqueTypes::Yes, - bound.rebind(target_principal), - upcast_principal.map_bound(|trait_ref| { - ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref) - }), - ) + .enter_forall(hr_target_principal, |target_principal| { + let source_principal = + self.infcx.instantiate_binder_with_fresh_vars( + obligation.cause.span, + HigherRankedType, + hr_source_principal, + ); + self.infcx.at(&obligation.cause, obligation.param_env).eq_trace( + DefineOpaqueTypes::Yes, + ToTrace::to_trace( + &obligation.cause, + true, + hr_target_principal, + hr_source_principal, + ), + target_principal, + source_principal, + ) + }) .map_err(|_| SelectionError::Unimplemented)? .into_obligations(), ); @@ -2599,19 +2616,41 @@ fn match_upcast_principal( // return ambiguity. Otherwise, if exactly one matches, equate // it with b_ty's projection. ty::ExistentialPredicate::Projection(target_projection) => { - let target_projection = bound.rebind(target_projection); + let hr_target_projection = bound.rebind(target_projection); + let mut matching_projections = - a_data.projection_bounds().filter(|source_projection| { + a_data.projection_bounds().filter(|&hr_source_projection| { // Eager normalization means that we can just use can_eq // here instead of equating and processing obligations. - source_projection.item_def_id() == target_projection.item_def_id() - && self.infcx.can_eq( - obligation.param_env, - *source_projection, - target_projection, - ) + hr_source_projection.item_def_id() == hr_target_projection.item_def_id() + && self.infcx.probe(|_| { + self.infcx + .enter_forall(hr_target_projection, |target_projection| { + let source_projection = + self.infcx.instantiate_binder_with_fresh_vars( + obligation.cause.span, + HigherRankedType, + hr_source_projection, + ); + self.infcx + .at(&obligation.cause, obligation.param_env) + .eq_trace( + DefineOpaqueTypes::Yes, + ToTrace::to_trace( + &obligation.cause, + true, + hr_target_projection, + hr_source_projection, + ), + target_projection, + source_projection, + ) + }) + .is_ok() + }) }); - let Some(source_projection) = matching_projections.next() else { + + let Some(hr_source_projection) = matching_projections.next() else { return Err(SelectionError::Unimplemented); }; if matching_projections.next().is_some() { @@ -2619,8 +2658,25 @@ fn match_upcast_principal( } nested.extend( self.infcx - .at(&obligation.cause, obligation.param_env) - .sup(DefineOpaqueTypes::Yes, target_projection, source_projection) + .enter_forall(hr_target_projection, |target_projection| { + let source_projection = + self.infcx.instantiate_binder_with_fresh_vars( + obligation.cause.span, + HigherRankedType, + hr_source_projection, + ); + self.infcx.at(&obligation.cause, obligation.param_env).eq_trace( + DefineOpaqueTypes::Yes, + ToTrace::to_trace( + &obligation.cause, + true, + hr_target_projection, + hr_source_projection, + ), + target_projection, + source_projection, + ) + }) .map_err(|_| SelectionError::Unimplemented)? .into_obligations(), );