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Coroutine closures implement regular Fn traits, when possible

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This commit is contained in:
Michael Goulet 2024-02-05 19:59:05 +00:00
parent 08af64e96b
commit b8c93f1223
5 changed files with 142 additions and 18 deletions
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18
compiler/rustc_ty_utils/src/instance.rs
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@ -278,6 +278,24 @@ fn resolve_associated_item<'tcx>(
def: ty::InstanceDef::FnPtrShim(trait_item_id, rcvr_args.type_at(0)),
args: rcvr_args,
}),
ty::CoroutineClosure(coroutine_closure_def_id, args) => {
// When a coroutine-closure implements the `Fn` traits, then it
// always dispatches to the `FnOnce` implementation. This is to
// ensure that the `closure_kind` of the resulting closure is in
// sync with the built-in trait implementations (since all of the
// implementations return `FnOnce::Output`).
if ty::ClosureKind::FnOnce == args.as_coroutine_closure().kind() {
Some(Instance::new(coroutine_closure_def_id, args))
} else {
Some(Instance {
def: ty::InstanceDef::ConstructCoroutineInClosureShim {
coroutine_closure_def_id,
target_kind: ty::ClosureKind::FnOnce,
},
args,
})
}
}
_ => bug!(
"no built-in definition for `{trait_ref}::{}` for non-fn type",
tcx.item_name(trait_item_id)