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

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This commit is contained in:
Ralf Jung 2023-12-02 22:25:14 +01:00
parent 0908f173fd
commit 5a20bac6b3
3 changed files with 22 additions and 0 deletions
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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");
}
}
}
}