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Rollup merge of #118551 - RalfJung:extern-types-bugs, r=compiler-errors

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more targeted errors when extern types end up in places they should not

Cc https://github.com/rust-lang/rust/issues/115709 -- this does not fix that bug but it makes the panics less obscure and makes it more clear that this is a deeper issue than just a little codegen oversight. (In https://github.com/rust-lang/rust/pull/116115 we decided we'd stick to causing ICEs here for now, rather than nicer errors. We can't currently show any errors pre-mono and probably we don't want post-mono checks when this gets stabilized anyway.)
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Takayuki Maeda 2023-12-04 21:19:44 +09:00 committed by GitHub
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9
compiler/rustc_codegen_llvm/src/builder.rs
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@ -489,6 +489,15 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
#[instrument(level = "trace", skip(self))]
fn load_operand(&mut self, place: PlaceRef<'tcx, &'ll Value>) -> OperandRef<'tcx, &'ll Value> {
if place.layout.is_unsized() {
let tail = self.tcx.struct_tail_with_normalize(place.layout.ty, |ty| ty, || {});
if matches!(tail.kind(), ty::Foreign(..)) {
// Unsized locals and, at least conceptually, even unsized arguments must be copied
// around, which requires dynamically determining their size. Therefore, we cannot
// allow `extern` types here. Consult t-opsem before removing this check.
panic!("unsized locals must not be `extern` types");
}
}
assert_eq!(place.llextra.is_some(), place.layout.is_unsized());
if place.layout.is_zst() {

1
compiler/rustc_codegen_ssa/src/mir/operand.rs
View File

@ -414,6 +414,7 @@ impl<'a, 'tcx, V: CodegenObject> OperandValue<V> {
// value is through `undef`/`poison`, and the store itself is useless.
}
OperandValue::Ref(r, None, source_align) => {
assert!(dest.layout.is_sized(), "cannot directly store unsized values");
if flags.contains(MemFlags::NONTEMPORAL) {
// HACK(nox): This is inefficient but there is no nontemporal memcpy.
let ty = bx.backend_type(dest.layout);

12
compiler/rustc_ty_utils/src/abi.rs
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@ -424,11 +424,23 @@ fn fn_abi_sanity_check<'tcx>(
}
PassMode::Indirect { meta_attrs: None, .. } => {
// No metadata, must be sized.
// Conceptually, unsized arguments must be copied around, which requires dynamically
// determining their size, which we cannot do without metadata. Consult
// t-opsem before removing this check.
assert!(arg.layout.is_sized());
}
PassMode::Indirect { meta_attrs: Some(_), on_stack, .. } => {
// With metadata. Must be unsized and not on the stack.
assert!(arg.layout.is_unsized() && !on_stack);
// Also, must not be `extern` type.
let tail = cx.tcx.struct_tail_with_normalize(arg.layout.ty, |ty| ty, || {});
if matches!(tail.kind(), ty::Foreign(..)) {
// These types do not have metadata, so having `meta_attrs` is bogus.
// Conceptually, unsized arguments must be copied around, which requires dynamically
// determining their size. Therefore, we cannot allow `extern` types here. Consult
// t-opsem before removing this check.
panic!("unsized arguments must not be `extern` types");
}
}
}
}