bjoernager/rust
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Rollup merge of #120139 - compiler-errors:fnonce-shim, r=BoxyUwU

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Do not normalize closure signature when building `FnOnce` shim

It is not necessary to normalize the closure signature when building an `FnOnce` shim for an `Fn`/`FnMut` closure. That closure shim is just calling `FnMut::call_mut(&mut self)` anyways.

It's also somewhat sketchy that we were ever doing this to begin with, since we're normalizing with a `ParamEnv::reveal_all()` param-env, which is definitely not right with possibly polymorphic substs.

This cuts out a tiny bit of unnecessary work in `Instance::resolve` and simplifies the signature because now we can unconditionally return an `Instance`.
This commit is contained in:
León Orell Valerian Liehr 2024-01-23 21:53:56 +01:00 • committed by GitHub
commit 6131ba62ad
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7 changed files with 20 additions and 18 deletions
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18
compiler/rustc_middle/src/ty/instance.rs
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@ -530,12 +530,12 @@ impl<'tcx> Instance<'tcx> {
def_id: DefId,
args: ty::GenericArgsRef<'tcx>,
requested_kind: ty::ClosureKind,
) -> Option<Instance<'tcx>> {
) -> Instance<'tcx> {
let actual_kind = args.as_closure().kind();
match needs_fn_once_adapter_shim(actual_kind, requested_kind) {
Ok(true) => Instance::fn_once_adapter_instance(tcx, def_id, args),
_ => Some(Instance::new(def_id, args)),
_ => Instance::new(def_id, args),
}
}
@ -550,7 +550,7 @@ impl<'tcx> Instance<'tcx> {
tcx: TyCtxt<'tcx>,
closure_did: DefId,
args: ty::GenericArgsRef<'tcx>,
) -> Option<Instance<'tcx>> {
) -> Instance<'tcx> {
let fn_once = tcx.require_lang_item(LangItem::FnOnce, None);
let call_once = tcx
.associated_items(fn_once)
@ -564,14 +564,12 @@ impl<'tcx> Instance<'tcx> {
let self_ty = Ty::new_closure(tcx, closure_did, args);
let sig = args.as_closure().sig();
let sig =
tcx.try_normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig).ok()?;
assert_eq!(sig.inputs().len(), 1);
let args = tcx.mk_args_trait(self_ty, [sig.inputs()[0].into()]);
let tupled_inputs_ty = args.as_closure().sig().map_bound(|sig| sig.inputs()[0]);
let tupled_inputs_ty = tcx.instantiate_bound_regions_with_erased(tupled_inputs_ty);
let args = tcx.mk_args_trait(self_ty, [tupled_inputs_ty.into()]);
debug!(?self_ty, ?sig);
Some(Instance { def, args })
debug!(?self_ty, args=?tupled_inputs_ty.tuple_fields());
Instance { def, args }
}
pub fn try_resolve_item_for_coroutine(