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Make gen blocks implement the Iterator trait

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This commit is contained in:
Oli Scherer
2023-10-20 22:48:37 +00:00
parent 621494382d
commit 998a816106
17 changed files with 286 additions and 7 deletions
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48
compiler/rustc_trait_selection/src/traits/project.rs
View File

@@ -1798,7 +1798,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
let self_ty = selcx.infcx.shallow_resolve(obligation.predicate.self_ty());
let lang_items = selcx.tcx().lang_items();
if [lang_items.gen_trait(), lang_items.future_trait()].contains(&Some(trait_ref.def_id))
if [lang_items.gen_trait(), lang_items.future_trait(), lang_items.iterator_trait()].contains(&Some(trait_ref.def_id))
|| selcx.tcx().fn_trait_kind_from_def_id(trait_ref.def_id).is_some()
{
true
@@ -2015,6 +2015,8 @@ fn confirm_select_candidate<'cx, 'tcx>(
confirm_coroutine_candidate(selcx, obligation, data)
} else if lang_items.future_trait() == Some(trait_def_id) {
confirm_future_candidate(selcx, obligation, data)
} else if lang_items.iterator_trait() == Some(trait_def_id) {
confirm_iterator_candidate(selcx, obligation, data)
} else if selcx.tcx().fn_trait_kind_from_def_id(trait_def_id).is_some() {
if obligation.predicate.self_ty().is_closure() {
confirm_closure_candidate(selcx, obligation, data)
@@ -2135,6 +2137,50 @@ fn confirm_future_candidate<'cx, 'tcx>(
.with_addl_obligations(obligations)
}
fn confirm_iterator_candidate<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,
nested: Vec<PredicateObligation<'tcx>>,
) -> Progress<'tcx> {
let ty::Coroutine(_, args, _) =
selcx.infcx.shallow_resolve(obligation.predicate.self_ty()).kind()
else {
unreachable!()
};
let gen_sig = args.as_coroutine().poly_sig();
let Normalized { value: gen_sig, obligations } = normalize_with_depth(
selcx,
obligation.param_env,
obligation.cause.clone(),
obligation.recursion_depth + 1,
gen_sig,
);
debug!(?obligation, ?gen_sig, ?obligations, "confirm_future_candidate");
let tcx = selcx.tcx();
let iter_def_id = tcx.require_lang_item(LangItem::Iterator, None);
let predicate = super::util::iterator_trait_ref_and_outputs(
tcx,
iter_def_id,
obligation.predicate.self_ty(),
gen_sig,
)
.map_bound(|(trait_ref, yield_ty)| {
debug_assert_eq!(tcx.associated_item(obligation.predicate.def_id).name, sym::Item);
ty::ProjectionPredicate {
projection_ty: ty::AliasTy::new(tcx, obligation.predicate.def_id, trait_ref.args),
term: yield_ty.into(),
}
});
confirm_param_env_candidate(selcx, obligation, predicate, false)
.with_addl_obligations(nested)
.with_addl_obligations(obligations)
}
fn confirm_builtin_candidate<'cx, 'tcx>(
selcx: &mut SelectionContext<'cx, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,

23
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View File

@@ -114,6 +114,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
self.assemble_coroutine_candidates(obligation, &mut candidates);
} else if lang_items.future_trait() == Some(def_id) {
self.assemble_future_candidates(obligation, &mut candidates);
} else if lang_items.iterator_trait() == Some(def_id) {
self.assemble_iterator_candidates(obligation, &mut candidates);
}
self.assemble_closure_candidates(obligation, &mut candidates);
@@ -211,9 +213,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// type/region parameters.
let self_ty = obligation.self_ty().skip_binder();
match self_ty.kind() {
// async constructs get lowered to a special kind of coroutine that
// `async`/`gen` constructs get lowered to a special kind of coroutine that
// should *not* `impl Coroutine`.
ty::Coroutine(did, ..) if !self.tcx().coroutine_is_async(*did) => {
ty::Coroutine(did, ..) if self.tcx().is_general_coroutine(*did) => {
debug!(?self_ty, ?obligation, "assemble_coroutine_candidates",);
candidates.vec.push(CoroutineCandidate);
@@ -243,6 +245,23 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
}
fn assemble_iterator_candidates(
&mut self,
obligation: &PolyTraitObligation<'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",);
candidates.vec.push(IteratorCandidate);
}
}
}
/// Checks for the artificial impl that the compiler will create for an obligation like `X :
/// FnMut<..>` where `X` is a closure type.
///

35
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
View File

@@ -93,6 +93,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
ImplSource::Builtin(BuiltinImplSource::Misc, vtable_future)
}
IteratorCandidate => {
let vtable_iterator = self.confirm_iterator_candidate(obligation)?;
ImplSource::Builtin(BuiltinImplSource::Misc, vtable_iterator)
}
FnPointerCandidate { is_const } => {
let data = self.confirm_fn_pointer_candidate(obligation, is_const)?;
ImplSource::Builtin(BuiltinImplSource::Misc, data)
@@ -780,6 +785,36 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
Ok(nested)
}
fn confirm_iterator_candidate(
&mut self,
obligation: &PolyTraitObligation<'tcx>,
) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
// Okay to skip binder because the args on coroutine types never
// touch bound regions, they just capture the in-scope
// type/region parameters.
let self_ty = self.infcx.shallow_resolve(obligation.self_ty().skip_binder());
let ty::Coroutine(coroutine_def_id, args, _) = *self_ty.kind() else {
bug!("closure candidate for non-closure {:?}", obligation);
};
debug!(?obligation, ?coroutine_def_id, ?args, "confirm_iterator_candidate");
let gen_sig = args.as_coroutine().poly_sig();
let trait_ref = super::util::iterator_trait_ref_and_outputs(
self.tcx(),
obligation.predicate.def_id(),
obligation.predicate.no_bound_vars().expect("iterator has no bound vars").self_ty(),
gen_sig,
)
.map_bound(|(trait_ref, ..)| trait_ref);
let nested = self.confirm_poly_trait_refs(obligation, trait_ref)?;
debug!(?trait_ref, ?nested, "iterator candidate obligations");
Ok(nested)
}
#[instrument(skip(self), level = "debug")]
fn confirm_closure_candidate(
&mut self,

6
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@@ -1888,6 +1888,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
| ClosureCandidate { .. }
| CoroutineCandidate
| FutureCandidate
| IteratorCandidate
| FnPointerCandidate { .. }
| BuiltinObjectCandidate
| BuiltinUnsizeCandidate
@@ -1916,6 +1917,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
| ClosureCandidate { .. }
| CoroutineCandidate
| FutureCandidate
| IteratorCandidate
| FnPointerCandidate { .. }
| BuiltinObjectCandidate
| BuiltinUnsizeCandidate
@@ -1950,6 +1952,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
| ClosureCandidate { .. }
| CoroutineCandidate
| FutureCandidate
| IteratorCandidate
| FnPointerCandidate { .. }
| BuiltinObjectCandidate
| BuiltinUnsizeCandidate
@@ -1964,6 +1967,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
| ClosureCandidate { .. }
| CoroutineCandidate
| FutureCandidate
| IteratorCandidate
| FnPointerCandidate { .. }
| BuiltinObjectCandidate
| BuiltinUnsizeCandidate
@@ -2070,6 +2074,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
| ClosureCandidate { .. }
| CoroutineCandidate
| FutureCandidate
| IteratorCandidate
| FnPointerCandidate { .. }
| BuiltinObjectCandidate
| BuiltinUnsizeCandidate
@@ -2080,6 +2085,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
| ClosureCandidate { .. }
| CoroutineCandidate
| FutureCandidate
| IteratorCandidate
| FnPointerCandidate { .. }
| BuiltinObjectCandidate
| BuiltinUnsizeCandidate

11
compiler/rustc_trait_selection/src/traits/util.rs
View File

@@ -297,6 +297,17 @@ pub fn future_trait_ref_and_outputs<'tcx>(
sig.map_bound(|sig| (trait_ref, sig.return_ty))
}
pub fn iterator_trait_ref_and_outputs<'tcx>(
tcx: TyCtxt<'tcx>,
iterator_def_id: DefId,
self_ty: Ty<'tcx>,
sig: ty::PolyGenSig<'tcx>,
) -> ty::Binder<'tcx, (ty::TraitRef<'tcx>, Ty<'tcx>)> {
assert!(!self_ty.has_escaping_bound_vars());
let trait_ref = ty::TraitRef::new(tcx, iterator_def_id, [self_ty]);
sig.map_bound(|sig| (trait_ref, sig.yield_ty))
}
pub fn impl_item_is_final(tcx: TyCtxt<'_>, assoc_item: &ty::AssocItem) -> bool {
assoc_item.defaultness(tcx).is_final()
&& tcx.defaultness(assoc_item.container_id(tcx)).is_final()