add ecx.probe_candidate
This commit is contained in:
lcnr
parent
cd68ead9ec
commit
795c2ef7d9
5 changed files with 276 additions and 294 deletions
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@ -6,7 +6,6 @@ use rustc_hir::def_id::DefId;
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use rustc_hir::{LangItem, Movability};
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use rustc_infer::traits::query::NoSolution;
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use rustc_infer::traits::util::supertraits;
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use rustc_middle::traits::solve::inspect::CandidateKind;
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use rustc_middle::traits::solve::{CanonicalResponse, Certainty, Goal, QueryResult};
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use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams, TreatProjections};
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use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt};
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@ -62,7 +61,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
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},
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};
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ecx.probe(|r| CandidateKind::Candidate { name: "impl".into(), result: *r }).enter(|ecx| {
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ecx.probe_candidate("impl").enter(|ecx| {
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let impl_substs = ecx.fresh_substs_for_item(impl_def_id);
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let impl_trait_ref = impl_trait_ref.subst(tcx, impl_substs);
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@ -90,16 +89,15 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
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&& trait_clause.polarity() == goal.predicate.polarity
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{
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// FIXME: Constness
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ecx.probe(|r| CandidateKind::Candidate { name: "assumption".into(), result: *r })
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.enter(|ecx| {
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let assumption_trait_pred = ecx.instantiate_binder_with_infer(trait_clause);
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ecx.eq(
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goal.param_env,
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goal.predicate.trait_ref,
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assumption_trait_pred.trait_ref,
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)?;
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then(ecx)
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})
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ecx.probe_candidate("assumption").enter(|ecx| {
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let assumption_trait_pred = ecx.instantiate_binder_with_infer(trait_clause);
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ecx.eq(
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goal.param_env,
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goal.predicate.trait_ref,
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assumption_trait_pred.trait_ref,
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)?;
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then(ecx)
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})
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} else {
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Err(NoSolution)
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}
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@ -136,15 +134,13 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
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let tcx = ecx.tcx();
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ecx.probe(|r| CandidateKind::Candidate { name: "trait alias".into(), result: *r }).enter(
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|ecx| {
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let nested_obligations = tcx
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.predicates_of(goal.predicate.def_id())
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.instantiate(tcx, goal.predicate.trait_ref.substs);
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ecx.add_goals(nested_obligations.predicates.into_iter().map(|p| goal.with(tcx, p)));
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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},
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)
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ecx.probe_candidate("trait alias").enter(|ecx| {
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let nested_obligations = tcx
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.predicates_of(goal.predicate.def_id())
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.instantiate(tcx, goal.predicate.trait_ref.substs);
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ecx.add_goals(nested_obligations.predicates.into_iter().map(|p| goal.with(tcx, p)));
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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})
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}
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fn consider_builtin_sized_candidate(
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@ -350,115 +346,109 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
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if b_ty.is_ty_var() {
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return ecx.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS);
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}
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ecx.probe(|r| CandidateKind::Candidate { name: "builtin unsize".into(), result: *r }).enter(
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|ecx| {
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match (a_ty.kind(), b_ty.kind()) {
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// Trait upcasting, or `dyn Trait + Auto + 'a` -> `dyn Trait + 'b`
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(&ty::Dynamic(_, _, ty::Dyn), &ty::Dynamic(_, _, ty::Dyn)) => {
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// Dyn upcasting is handled separately, since due to upcasting,
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// when there are two supertraits that differ by substs, we
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// may return more than one query response.
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Err(NoSolution)
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ecx.probe_candidate("builtin unsize").enter(|ecx| {
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match (a_ty.kind(), b_ty.kind()) {
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// Trait upcasting, or `dyn Trait + Auto + 'a` -> `dyn Trait + 'b`
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(&ty::Dynamic(_, _, ty::Dyn), &ty::Dynamic(_, _, ty::Dyn)) => {
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// Dyn upcasting is handled separately, since due to upcasting,
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// when there are two supertraits that differ by substs, we
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// may return more than one query response.
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Err(NoSolution)
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}
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// `T` -> `dyn Trait` unsizing
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(_, &ty::Dynamic(data, region, ty::Dyn)) => {
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// Can only unsize to an object-safe type
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if data
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.principal_def_id()
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.is_some_and(|def_id| !tcx.check_is_object_safe(def_id))
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{
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return Err(NoSolution);
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}
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// `T` -> `dyn Trait` unsizing
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(_, &ty::Dynamic(data, region, ty::Dyn)) => {
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// Can only unsize to an object-safe type
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if data
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.principal_def_id()
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.is_some_and(|def_id| !tcx.check_is_object_safe(def_id))
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{
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return Err(NoSolution);
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}
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let Some(sized_def_id) = tcx.lang_items().sized_trait() else {
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let Some(sized_def_id) = tcx.lang_items().sized_trait() else {
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return Err(NoSolution);
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};
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// Check that the type implements all of the predicates of the def-id.
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// (i.e. the principal, all of the associated types match, and any auto traits)
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ecx.add_goals(
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data.iter().map(|pred| goal.with(tcx, pred.with_self_ty(tcx, a_ty))),
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);
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// The type must be Sized to be unsized.
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ecx.add_goal(goal.with(tcx, ty::TraitRef::new(tcx, sized_def_id, [a_ty])));
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// The type must outlive the lifetime of the `dyn` we're unsizing into.
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ecx.add_goal(
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goal.with(tcx, ty::Binder::dummy(ty::OutlivesPredicate(a_ty, region))),
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);
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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// `[T; n]` -> `[T]` unsizing
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(&ty::Array(a_elem_ty, ..), &ty::Slice(b_elem_ty)) => {
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// We just require that the element type stays the same
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ecx.eq(goal.param_env, a_elem_ty, b_elem_ty)?;
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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// Struct unsizing `Struct<T>` -> `Struct<U>` where `T: Unsize<U>`
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(&ty::Adt(a_def, a_substs), &ty::Adt(b_def, b_substs))
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if a_def.is_struct() && a_def.did() == b_def.did() =>
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{
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let unsizing_params = tcx.unsizing_params_for_adt(a_def.did());
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// We must be unsizing some type parameters. This also implies
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// that the struct has a tail field.
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if unsizing_params.is_empty() {
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return Err(NoSolution);
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}
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let tail_field = a_def
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.non_enum_variant()
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.fields
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.raw
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.last()
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.expect("expected unsized ADT to have a tail field");
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let tail_field_ty = tcx.type_of(tail_field.did);
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let a_tail_ty = tail_field_ty.subst(tcx, a_substs);
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let b_tail_ty = tail_field_ty.subst(tcx, b_substs);
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// Substitute just the unsizing params from B into A. The type after
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// this substitution must be equal to B. This is so we don't unsize
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// unrelated type parameters.
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let new_a_substs =
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tcx.mk_substs_from_iter(a_substs.iter().enumerate().map(|(i, a)| {
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if unsizing_params.contains(i as u32) { b_substs[i] } else { a }
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}));
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let unsized_a_ty = tcx.mk_adt(a_def, new_a_substs);
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// Finally, we require that `TailA: Unsize<TailB>` for the tail field
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// types.
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ecx.eq(goal.param_env, unsized_a_ty, b_ty)?;
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ecx.add_goal(goal.with(
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tcx,
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ty::TraitRef::new(tcx, goal.predicate.def_id(), [a_tail_ty, b_tail_ty]),
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));
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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// Tuple unsizing `(.., T)` -> `(.., U)` where `T: Unsize<U>`
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(&ty::Tuple(a_tys), &ty::Tuple(b_tys))
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if a_tys.len() == b_tys.len() && !a_tys.is_empty() =>
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{
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let (a_last_ty, a_rest_tys) = a_tys.split_last().unwrap();
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let b_last_ty = b_tys.last().unwrap();
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// Substitute just the tail field of B., and require that they're equal.
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let unsized_a_ty =
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tcx.mk_tup_from_iter(a_rest_tys.iter().chain([b_last_ty]).copied());
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ecx.eq(goal.param_env, unsized_a_ty, b_ty)?;
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// Similar to ADTs, require that the rest of the fields are equal.
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ecx.add_goal(goal.with(
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tcx,
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ty::TraitRef::new(
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tcx,
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goal.predicate.def_id(),
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[*a_last_ty, *b_last_ty],
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),
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));
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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_ => Err(NoSolution),
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// Check that the type implements all of the predicates of the def-id.
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// (i.e. the principal, all of the associated types match, and any auto traits)
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ecx.add_goals(
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data.iter().map(|pred| goal.with(tcx, pred.with_self_ty(tcx, a_ty))),
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);
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// The type must be Sized to be unsized.
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ecx.add_goal(goal.with(tcx, ty::TraitRef::new(tcx, sized_def_id, [a_ty])));
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// The type must outlive the lifetime of the `dyn` we're unsizing into.
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ecx.add_goal(
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goal.with(tcx, ty::Binder::dummy(ty::OutlivesPredicate(a_ty, region))),
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);
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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},
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)
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// `[T; n]` -> `[T]` unsizing
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(&ty::Array(a_elem_ty, ..), &ty::Slice(b_elem_ty)) => {
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// We just require that the element type stays the same
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ecx.eq(goal.param_env, a_elem_ty, b_elem_ty)?;
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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// Struct unsizing `Struct<T>` -> `Struct<U>` where `T: Unsize<U>`
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(&ty::Adt(a_def, a_substs), &ty::Adt(b_def, b_substs))
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if a_def.is_struct() && a_def.did() == b_def.did() =>
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{
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let unsizing_params = tcx.unsizing_params_for_adt(a_def.did());
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// We must be unsizing some type parameters. This also implies
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// that the struct has a tail field.
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if unsizing_params.is_empty() {
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return Err(NoSolution);
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}
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let tail_field = a_def
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.non_enum_variant()
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.fields
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.raw
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.last()
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.expect("expected unsized ADT to have a tail field");
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let tail_field_ty = tcx.type_of(tail_field.did);
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let a_tail_ty = tail_field_ty.subst(tcx, a_substs);
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let b_tail_ty = tail_field_ty.subst(tcx, b_substs);
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// Substitute just the unsizing params from B into A. The type after
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// this substitution must be equal to B. This is so we don't unsize
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// unrelated type parameters.
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let new_a_substs =
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tcx.mk_substs_from_iter(a_substs.iter().enumerate().map(|(i, a)| {
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if unsizing_params.contains(i as u32) { b_substs[i] } else { a }
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}));
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let unsized_a_ty = tcx.mk_adt(a_def, new_a_substs);
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// Finally, we require that `TailA: Unsize<TailB>` for the tail field
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// types.
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ecx.eq(goal.param_env, unsized_a_ty, b_ty)?;
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ecx.add_goal(goal.with(
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tcx,
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ty::TraitRef::new(tcx, goal.predicate.def_id(), [a_tail_ty, b_tail_ty]),
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));
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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// Tuple unsizing `(.., T)` -> `(.., U)` where `T: Unsize<U>`
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(&ty::Tuple(a_tys), &ty::Tuple(b_tys))
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if a_tys.len() == b_tys.len() && !a_tys.is_empty() =>
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{
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let (a_last_ty, a_rest_tys) = a_tys.split_last().unwrap();
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let b_last_ty = b_tys.last().unwrap();
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// Substitute just the tail field of B., and require that they're equal.
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let unsized_a_ty =
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tcx.mk_tup_from_iter(a_rest_tys.iter().chain([b_last_ty]).copied());
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ecx.eq(goal.param_env, unsized_a_ty, b_ty)?;
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// Similar to ADTs, require that the rest of the fields are equal.
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ecx.add_goal(goal.with(
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tcx,
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ty::TraitRef::new(tcx, goal.predicate.def_id(), [*a_last_ty, *b_last_ty]),
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));
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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}
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_ => Err(NoSolution),
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}
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})
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}
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fn consider_builtin_dyn_upcast_candidates(
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@ -488,11 +478,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
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}
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let mut unsize_dyn_to_principal = |principal: Option<ty::PolyExistentialTraitRef<'tcx>>| {
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ecx.probe(|r| CandidateKind::Candidate {
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name: "upcast dyn to principle".into(),
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result: *r,
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})
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.enter(|ecx| -> Result<_, NoSolution> {
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ecx.probe_candidate("upcast dyn to principle").enter(|ecx| -> Result<_, NoSolution> {
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// Require that all of the trait predicates from A match B, except for
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// the auto traits. We do this by constructing a new A type with B's
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// auto traits, and equating these types.
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@ -714,21 +700,20 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
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goal: Goal<'tcx, TraitPredicate<'tcx>>,
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constituent_tys: impl Fn(&EvalCtxt<'_, 'tcx>, Ty<'tcx>) -> Result<Vec<Ty<'tcx>>, NoSolution>,
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) -> QueryResult<'tcx> {
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self.probe(|r| CandidateKind::Candidate { name: "constituent tys".into(), result: *r })
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.enter(|ecx| {
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ecx.add_goals(
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constituent_tys(ecx, goal.predicate.self_ty())?
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.into_iter()
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.map(|ty| {
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goal.with(
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ecx.tcx(),
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ty::Binder::dummy(goal.predicate.with_self_ty(ecx.tcx(), ty)),
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)
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})
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.collect::<Vec<_>>(),
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);
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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})
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self.probe_candidate("constituent tys").enter(|ecx| {
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ecx.add_goals(
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constituent_tys(ecx, goal.predicate.self_ty())?
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.into_iter()
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.map(|ty| {
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goal.with(
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ecx.tcx(),
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ty::Binder::dummy(goal.predicate.with_self_ty(ecx.tcx(), ty)),
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)
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})
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.collect::<Vec<_>>(),
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);
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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})
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}
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#[instrument(level = "debug", skip(self))]
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