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Don't ICE when generating Fn shim for async closure with borrowck error

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This commit is contained in:
Michael Goulet 2024-09-15 16:07:08 -04:00
parent 13b5a4e43b
commit 57a7e514a4
3 changed files with 37 additions and 6 deletions
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17
compiler/rustc_mir_transform/src/shim.rs
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@ -1070,19 +1070,26 @@ fn build_construct_coroutine_by_move_shim<'tcx>(
let locals = local_decls_for_sig(&sig, span);
let mut fields = vec![];
// Move all of the closure args.
for idx in 1..sig.inputs().len() {
fields.push(Operand::Move(Local::from_usize(idx + 1).into()));
}
for (idx, ty) in args.as_coroutine_closure().upvar_tys().iter().enumerate() {
if receiver_by_ref {
// The only situation where it's possible is when we capture immuatable references,
// since those don't need to be reborrowed with the closure's env lifetime. Since
// references are always `Copy`, just emit a copy.
assert_matches!(
ty.kind(),
ty::Ref(_, _, hir::Mutability::Not),
"field should be captured by immutable ref if we have an `Fn` instance"
);
if !matches!(ty.kind(), ty::Ref(_, _, hir::Mutability::Not)) {
// This copy is only sound if it's a `&T`. This may be
// reachable e.g. when eagerly computing the `Fn` instance
// of an async closure that doesn't borrowck.
tcx.dcx().delayed_bug(format!(
"field should be captured by immutable ref if we have \
an `Fn` instance, but it was: {ty}"
));
}
fields.push(Operand::Copy(tcx.mk_place_field(
self_local,
FieldIdx::from_usize(idx),