rsmith accepted this revision.
rsmith added a comment.
This revision is now accepted and ready to land.
This looks fine as far as it goes, but it doesn't fix all cases of incorrect
behavior of `__has_unique_object_representations` due to
`[[no_unique_address]]`. Feel free to either to land this as-is and leave the
other case to a separate patch, or fix it as a revision of this same change. I
would expect we'll want to unify the code paths for base classes and non-static
data members, which might be better done all at once.
================
Comment at: clang/lib/AST/ASTContext.cpp:2580-2581
if (!isStructEmpty(Base.getType())) {
llvm::Optional<int64_t> Size = structHasUniqueObjectRepresentations(
Context, Base.getType()->castAs<RecordType>()->getDecl());
if (!Size)
----------------
We need to do this for non-empty `[[no_unique_address]]` members of class type
too, to handle tail padding reuse in cases such as:
```
struct A {
~A();
int a;
char b;
};
struct B {
[[no_unique_address]] A a;
char c[3];
};
static_assert(sizeof(B) == 8, "");
static_assert(__has_unique_object_representations(B), "");
```
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D89649/new/
https://reviews.llvm.org/D89649
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