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 | 250 |
1 files changed, 129 insertions, 121 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/project_goals.rs b/compiler/rustc_trait_selection/src/solve/project_goals.rs index 33c66d072..14cb43b89 100644 --- a/compiler/rustc_trait_selection/src/solve/project_goals.rs +++ b/compiler/rustc_trait_selection/src/solve/project_goals.rs @@ -1,24 +1,23 @@ -use crate::traits::{specialization_graph, translate_substs}; +use crate::traits::specialization_graph; -use super::assembly; -use super::trait_goals::structural_traits; -use super::{Certainty, EvalCtxt, Goal, QueryResult}; +use super::assembly::{self, structural_traits}; +use super::EvalCtxt; use rustc_errors::ErrorGuaranteed; use rustc_hir::def::DefKind; use rustc_hir::def_id::DefId; use rustc_hir::LangItem; -use rustc_infer::infer::InferCtxt; use rustc_infer::traits::query::NoSolution; use rustc_infer::traits::specialization_graph::LeafDef; use rustc_infer::traits::Reveal; +use rustc_middle::traits::solve::{CanonicalResponse, Certainty, Goal, QueryResult}; use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams}; use rustc_middle::ty::ProjectionPredicate; use rustc_middle::ty::{self, Ty, TyCtxt}; use rustc_middle::ty::{ToPredicate, TypeVisitableExt}; use rustc_span::{sym, DUMMY_SP}; -use std::iter; impl<'tcx> EvalCtxt<'_, 'tcx> { + #[instrument(level = "debug", skip(self), ret)] pub(super) fn compute_projection_goal( &mut self, goal: Goal<'tcx, ProjectionPredicate<'tcx>>, @@ -32,57 +31,12 @@ 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_candidates_and_discard_reservation_impls(candidates) + self.merge_candidates(candidates) } else { - let predicate = goal.predicate; - let unconstrained_rhs = match predicate.term.unpack() { - ty::TermKind::Ty(_) => self.next_ty_infer().into(), - ty::TermKind::Const(ct) => self.next_const_infer(ct.ty()).into(), - }; - let unconstrained_predicate = ty::Clause::Projection(ProjectionPredicate { - projection_ty: goal.predicate.projection_ty, - term: unconstrained_rhs, - }); - let (_has_changed, normalize_certainty) = self.in_projection_eq_hack(|this| { - this.evaluate_goal(goal.with(this.tcx(), unconstrained_predicate)) - })?; - - let nested_eq_goals = self.eq(goal.param_env, unconstrained_rhs, predicate.term)?; - let eval_certainty = self.evaluate_all(nested_eq_goals)?; - self.make_canonical_response(normalize_certainty.unify_and(eval_certainty)) + self.set_normalizes_to_hack_goal(goal); + self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) } } - - /// This sets a flag used by a debug assert in [`EvalCtxt::evaluate_goal`], - /// see the comment in that method for more details. - fn in_projection_eq_hack<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T { - self.in_projection_eq_hack = true; - let result = f(self); - self.in_projection_eq_hack = false; - result - } - - /// After normalizing the projection to `normalized_alias` with the given - /// `normalization_certainty`, constrain the inference variable `term` to it - /// and return a query response. - fn eq_term_and_make_canonical_response( - &mut self, - goal: Goal<'tcx, ProjectionPredicate<'tcx>>, - normalization_certainty: Certainty, - normalized_alias: impl Into<ty::Term<'tcx>>, - ) -> QueryResult<'tcx> { - // The term of our goal should be fully unconstrained, so this should never fail. - // - // It can however be ambiguous when the `normalized_alias` contains a projection. - let nested_goals = self - .eq(goal.param_env, goal.predicate.term, normalized_alias.into()) - .expect("failed to unify with unconstrained term"); - - let unify_certainty = - self.evaluate_all(nested_goals).expect("failed to unify with unconstrained term"); - - self.make_canonical_response(normalization_certainty.unify_and(unify_certainty)) - } } impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { @@ -90,6 +44,10 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { self.self_ty() } + fn trait_ref(self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> { + self.projection_ty.trait_ref(tcx) + } + fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self { self.with_self_ty(tcx, self_ty) } @@ -110,19 +68,14 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { ecx.probe(|ecx| { let assumption_projection_pred = ecx.instantiate_binder_with_infer(poly_projection_pred); - let mut nested_goals = ecx.eq( + ecx.eq( goal.param_env, goal.predicate.projection_ty, assumption_projection_pred.projection_ty, )?; - nested_goals.extend(requirements); - let subst_certainty = ecx.evaluate_all(nested_goals)?; - - ecx.eq_term_and_make_canonical_response( - goal, - subst_certainty, - assumption_projection_pred.term, - ) + ecx.eq(goal.param_env, goal.predicate.term, assumption_projection_pred.term)?; + ecx.add_goals(requirements); + ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) }) } else { Err(NoSolution) @@ -138,21 +91,22 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { && poly_projection_pred.projection_def_id() == goal.predicate.def_id() { ecx.probe(|ecx| { + let tcx = ecx.tcx(); + let assumption_projection_pred = ecx.instantiate_binder_with_infer(poly_projection_pred); - let mut nested_goals = ecx.eq( + ecx.eq( goal.param_env, goal.predicate.projection_ty, assumption_projection_pred.projection_ty, )?; - let tcx = ecx.tcx(); let ty::Dynamic(bounds, _, _) = *goal.predicate.self_ty().kind() else { bug!("expected object type in `consider_object_bound_candidate`"); }; - nested_goals.extend( + ecx.add_goals( structural_traits::predicates_for_object_candidate( - ecx, + &ecx, goal.param_env, goal.predicate.projection_ty.trait_ref(tcx), bounds, @@ -160,14 +114,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { .into_iter() .map(|pred| goal.with(tcx, pred)), ); - - let subst_certainty = ecx.evaluate_all(nested_goals)?; - - ecx.eq_term_and_make_canonical_response( - goal, - subst_certainty, - assumption_projection_pred.term, - ) + ecx.eq(goal.param_env, goal.predicate.term, assumption_projection_pred.term)?; + ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) }) } else { Err(NoSolution) @@ -183,10 +131,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { let goal_trait_ref = goal.predicate.projection_ty.trait_ref(tcx); let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap(); - let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::AsPlaceholder }; - if iter::zip(goal_trait_ref.substs, impl_trait_ref.skip_binder().substs) - .any(|(goal, imp)| !drcx.generic_args_may_unify(goal, imp)) - { + let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::ForLookup }; + if !drcx.substs_refs_may_unify(goal_trait_ref.substs, impl_trait_ref.skip_binder().substs) { return Err(NoSolution); } @@ -194,28 +140,27 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { let impl_substs = ecx.fresh_substs_for_item(impl_def_id); let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs); - let mut nested_goals = ecx.eq(goal.param_env, goal_trait_ref, impl_trait_ref)?; + 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)); - - nested_goals.extend(where_clause_bounds); - let match_impl_certainty = ecx.evaluate_all(nested_goals)?; + 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.infcx, + ecx, goal.param_env, goal_trait_ref, goal.predicate.def_id(), impl_def_id )? else { - return ecx.make_canonical_response(match_impl_certainty.unify_and(Certainty::AMBIGUOUS)); + return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS); }; if !assoc_def.item.defaultness(tcx).has_value() { @@ -240,8 +185,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { goal_trait_ref.def_id, impl_substs, ); - let substs = translate_substs( - ecx.infcx, + let substs = ecx.translate_substs( goal.param_env, impl_def_id, impl_substs_with_gat, @@ -262,7 +206,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { ty.map_bound(|ty| ty.into()) }; - ecx.eq_term_and_make_canonical_response(goal, match_impl_certainty, term.subst(tcx, substs)) + ecx.eq(goal.param_env, goal.predicate.term, term.subst(tcx, substs))?; + ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) }) } @@ -301,20 +246,31 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { bug!("`PointerLike` does not have an associated type: {:?}", goal); } + fn consider_builtin_fn_ptr_trait_candidate( + _ecx: &mut EvalCtxt<'_, 'tcx>, + goal: Goal<'tcx, Self>, + ) -> QueryResult<'tcx> { + bug!("`FnPtr` does not have an associated type: {:?}", goal); + } + fn consider_builtin_fn_trait_candidates( ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, Self>, goal_kind: ty::ClosureKind, ) -> QueryResult<'tcx> { let tcx = ecx.tcx(); - let Some(tupled_inputs_and_output) = - structural_traits::extract_tupled_inputs_and_output_from_callable( - tcx, - goal.predicate.self_ty(), - goal_kind, - )? else { - return ecx.make_canonical_response(Certainty::AMBIGUOUS); - }; + let tupled_inputs_and_output = + match structural_traits::extract_tupled_inputs_and_output_from_callable( + tcx, + goal.predicate.self_ty(), + goal_kind, + )? { + Some(tupled_inputs_and_output) => tupled_inputs_and_output, + None => { + return ecx + .evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS); + } + }; let output_is_sized_pred = tupled_inputs_and_output .map_bound(|(_, output)| tcx.at(DUMMY_SP).mk_trait_ref(LangItem::Sized, [output])); @@ -378,27 +334,21 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { LangItem::Sized, [ty::GenericArg::from(goal.predicate.self_ty())], )); - - let (_, is_sized_certainty) = - ecx.evaluate_goal(goal.with(tcx, sized_predicate))?; - return ecx.eq_term_and_make_canonical_response( - goal, - is_sized_certainty, - tcx.types.unit, - ); + ecx.add_goal(goal.with(tcx, sized_predicate)); + tcx.types.unit } ty::Adt(def, substs) if def.is_struct() => { - match def.non_enum_variant().fields.last() { + match def.non_enum_variant().fields.raw.last() { None => tcx.types.unit, Some(field_def) => { let self_ty = field_def.ty(tcx, substs); - let new_goal = goal.with( + ecx.add_goal(goal.with( tcx, ty::Binder::dummy(goal.predicate.with_self_ty(tcx, self_ty)), - ); - let (_, certainty) = ecx.evaluate_goal(new_goal)?; - return ecx.make_canonical_response(certainty); + )); + return ecx + .evaluate_added_goals_and_make_canonical_response(Certainty::Yes); } } } @@ -407,12 +357,12 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { ty::Tuple(elements) => match elements.last() { None => tcx.types.unit, Some(&self_ty) => { - let new_goal = goal.with( + ecx.add_goal(goal.with( tcx, ty::Binder::dummy(goal.predicate.with_self_ty(tcx, self_ty)), - ); - let (_, certainty) = ecx.evaluate_goal(new_goal)?; - return ecx.make_canonical_response(certainty); + )); + return ecx + .evaluate_added_goals_and_make_canonical_response(Certainty::Yes); } }, @@ -425,7 +375,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { ), }; - ecx.eq_term_and_make_canonical_response(goal, Certainty::Yes, metadata_ty) + ecx.eq(goal.param_env, goal.predicate.term, metadata_ty.into())?; + ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) }) } @@ -512,7 +463,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { fn consider_builtin_dyn_upcast_candidates( _ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, Self>, - ) -> Vec<super::CanonicalResponse<'tcx>> { + ) -> Vec<CanonicalResponse<'tcx>> { bug!("`Unsize` does not have an associated type: {:?}", goal); } @@ -520,8 +471,65 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { ecx: &mut EvalCtxt<'_, 'tcx>, goal: Goal<'tcx, Self>, ) -> QueryResult<'tcx> { - let discriminant = goal.predicate.self_ty().discriminant_ty(ecx.tcx()); - ecx.probe(|ecx| ecx.eq_term_and_make_canonical_response(goal, Certainty::Yes, discriminant)) + 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::RawPtr(..) + | ty::Ref(..) + | ty::FnDef(..) + | ty::FnPtr(..) + | ty::Closure(..) + | ty::Infer(ty::IntVar(..) | ty::FloatVar(..)) + | ty::Generator(..) + | ty::GeneratorWitness(..) + | ty::GeneratorWitnessMIR(..) + | ty::Never + | ty::Foreign(..) + | ty::Adt(_, _) + | ty::Str + | ty::Slice(_) + | ty::Dynamic(_, _, _) + | ty::Tuple(_) + | ty::Error(_) => self_ty.discriminant_ty(ecx.tcx()), + + // We do not call `Ty::discriminant_ty` on alias, param, or placeholder + // types, which return `<self_ty as DiscriminantKind>::Discriminant` + // (or ICE in the case of placeholders). Projecting a type to itself + // is never really productive. + ty::Alias(_, _) | ty::Param(_) | ty::Placeholder(..) => { + return Err(NoSolution); + } + + ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) + | ty::Bound(..) => bug!( + "unexpected self ty `{:?}` when normalizing `<T as DiscriminantKind>::Discriminant`", + goal.predicate.self_ty() + ), + }; + + ecx.probe(|ecx| { + ecx.eq(goal.param_env, goal.predicate.term, discriminant_ty.into())?; + ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes) + }) + } + + fn consider_builtin_destruct_candidate( + _ecx: &mut EvalCtxt<'_, 'tcx>, + goal: Goal<'tcx, Self>, + ) -> QueryResult<'tcx> { + bug!("`Destruct` does not have an associated type: {:?}", goal); + } + + fn consider_builtin_transmute_candidate( + _ecx: &mut EvalCtxt<'_, 'tcx>, + goal: Goal<'tcx, Self>, + ) -> QueryResult<'tcx> { + bug!("`BikeshedIntrinsicFrom` does not have an associated type: {:?}", goal) } } @@ -529,15 +537,15 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> { /// /// FIXME: We should merge these 3 implementations as it's likely that they otherwise /// diverge. -#[instrument(level = "debug", skip(infcx, param_env), ret)] +#[instrument(level = "debug", skip(ecx, param_env), ret)] fn fetch_eligible_assoc_item_def<'tcx>( - infcx: &InferCtxt<'tcx>, + ecx: &EvalCtxt<'_, 'tcx>, param_env: ty::ParamEnv<'tcx>, goal_trait_ref: ty::TraitRef<'tcx>, trait_assoc_def_id: DefId, impl_def_id: DefId, ) -> Result<Option<LeafDef>, NoSolution> { - let node_item = specialization_graph::assoc_def(infcx.tcx, impl_def_id, trait_assoc_def_id) + let node_item = specialization_graph::assoc_def(ecx.tcx(), impl_def_id, trait_assoc_def_id) .map_err(|ErrorGuaranteed { .. }| NoSolution)?; let eligible = if node_item.is_final() { @@ -549,7 +557,7 @@ fn fetch_eligible_assoc_item_def<'tcx>( // 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 = infcx.resolve_vars_if_possible(goal_trait_ref); + let poly_trait_ref = ecx.resolve_vars_if_possible(goal_trait_ref); !poly_trait_ref.still_further_specializable() } else { debug!(?node_item.item.def_id, "not eligible due to default"); |