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Implement FusedIterator for gen block

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This commit is contained in:
Shoyu Vanilla 2024-03-22 00:48:36 +09:00
parent 03994e498d
commit ae4c5c891e
10 changed files with 105 additions and 7 deletions
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9
compiler/rustc_trait_selection/src/solve/assembly/mod.rs
View file

@ -215,6 +215,13 @@ pub(super) trait GoalKind<'tcx>:
goal: Goal<'tcx, Self>,
) -> QueryResult<'tcx>;
/// A coroutine (that comes from a `gen` desugaring) is known to implement
/// `FusedIterator`
fn consider_builtin_fused_iterator_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
) -> QueryResult<'tcx>;
fn consider_builtin_async_iterator_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
@ -497,6 +504,8 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
G::consider_builtin_future_candidate(self, goal)
} else if lang_items.iterator_trait() == Some(trait_def_id) {
G::consider_builtin_iterator_candidate(self, goal)
} else if lang_items.fused_iterator_trait() == Some(trait_def_id) {
G::consider_builtin_fused_iterator_candidate(self, goal)
} else if lang_items.async_iterator_trait() == Some(trait_def_id) {
G::consider_builtin_async_iterator_candidate(self, goal)
} else if lang_items.coroutine_trait() == Some(trait_def_id) {

7
compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
View file

@ -647,6 +647,13 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
)
}
fn consider_builtin_fused_iterator_candidate(
_ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
) -> QueryResult<'tcx> {
bug!("`FusedIterator` does not have an associated type: {:?}", goal);
}
fn consider_builtin_async_iterator_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,

22
compiler/rustc_trait_selection/src/solve/trait_goals.rs
View file

@ -456,6 +456,28 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
}
fn consider_builtin_fused_iterator_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
) -> QueryResult<'tcx> {
if goal.predicate.polarity != ty::ImplPolarity::Positive {
return Err(NoSolution);
}
let ty::Coroutine(def_id, _) = *goal.predicate.self_ty().kind() else {
return Err(NoSolution);
};
// Coroutines are not iterators unless they come from `gen` desugaring
let tcx = ecx.tcx();
if !tcx.coroutine_is_gen(def_id) {
return Err(NoSolution);
}
// Gen coroutines unconditionally implement `FusedIterator`
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
}
fn consider_builtin_async_iterator_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,

33
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View file

@ -118,6 +118,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
self.assemble_future_candidates(obligation, &mut candidates);
} else if lang_items.iterator_trait() == Some(def_id) {
self.assemble_iterator_candidates(obligation, &mut candidates);
} else if lang_items.fused_iterator_trait() == Some(def_id) {
self.assemble_fused_iterator_candidates(obligation, &mut candidates);
} else if lang_items.async_iterator_trait() == Some(def_id) {
self.assemble_async_iterator_candidates(obligation, &mut candidates);
} else if lang_items.async_fn_kind_helper() == Some(def_id) {
@ -302,14 +304,31 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
candidates: &mut SelectionCandidateSet<'tcx>,
) {
let self_ty = obligation.self_ty().skip_binder();
if let ty::Coroutine(did, ..) = self_ty.kind() {
// gen constructs get lowered to a special kind of coroutine that
// should directly `impl Iterator`.
if self.tcx().coroutine_is_gen(*did) {
debug!(?self_ty, ?obligation, "assemble_iterator_candidates",);
// gen constructs get lowered to a special kind of coroutine that
// should directly `impl Iterator`.
if let ty::Coroutine(did, ..) = self_ty.kind()
&& self.tcx().coroutine_is_gen(*did)
{
debug!(?self_ty, ?obligation, "assemble_iterator_candidates",);
candidates.vec.push(IteratorCandidate);
}
candidates.vec.push(IteratorCandidate);
}
}
fn assemble_fused_iterator_candidates(
&mut self,
obligation: &PolyTraitObligation<'tcx>,
candidates: &mut SelectionCandidateSet<'tcx>,
) {
let self_ty = obligation.self_ty().skip_binder();
// gen constructs get lowered to a special kind of coroutine that
// should directly `impl FusedIterator`.
if let ty::Coroutine(did, ..) = self_ty.kind()
&& self.tcx().coroutine_is_gen(*did)
{
debug!(?self_ty, ?obligation, "assemble_fused_iterator_candidates",);
candidates.vec.push(BuiltinCandidate { has_nested: false });
}
}

2
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View file

@ -267,6 +267,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
self.copy_clone_conditions(obligation)
} else if Some(trait_def) == lang_items.clone_trait() {
self.copy_clone_conditions(obligation)
} else if Some(trait_def) == lang_items.fused_iterator_trait() {
self.fused_iterator_conditions(obligation)
} else {
bug!("unexpected builtin trait {:?}", trait_def)
};

14
compiler/rustc_trait_selection/src/traits/select/mod.rs
View file

@ -2259,6 +2259,20 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
}
}
fn fused_iterator_conditions(
&mut self,
obligation: &PolyTraitObligation<'tcx>,
) -> BuiltinImplConditions<'tcx> {
let self_ty = self.infcx.shallow_resolve(obligation.self_ty().skip_binder());
if let ty::Coroutine(did, ..) = *self_ty.kind()
&& self.tcx().coroutine_is_gen(did)
{
BuiltinImplConditions::Where(ty::Binder::dummy(Vec::new()))
} else {
BuiltinImplConditions::None
}
}
/// For default impls, we need to break apart a type into its
/// "constituent types" -- meaning, the types that it contains.
///