inclyc added inline comments.
================
Comment at: clang/test/Sema/offsetof.c:79
+ int a;
+ struct B // no-error, struct B is not defined within __builtin_offsetof
directly
+ {
----------------
aaron.ballman wrote:
> inclyc wrote:
> > aaron.ballman wrote:
> > > I think this is defensible. The wording in the standard is "If the
> > > specified type defines a new type or if the specified member is a
> > > bit-field, the behavior is undefined." and the specified type in this
> > > case is `struct A`; that `struct A` happens to also define `struct B` is
> > > immaterial.
> > >
> > > However, the intent behind the change to the rule is to support older
> > > implementations of `offsetof` to protect them from having to deal with a
> > > case like: `offsetof(struct S { int a, b }, b);` where `offsetof` is a
> > > macro and thus the comma between `a` and `b` is treated as a separator.
> > > So there's a part of me that wonders if we want to also support
> > > diagnosing this case. But then we'd have to look at the declarator
> > > context more recursively to see whether any of the contexts on the stack
> > > are an `offsetof` context and that might be tricky.
> > >
> > > Thoughts?
> > FWIW, gcc seems just rejects all definitions in this context. (Perhaps
> > during Parsing the statements). If we add a bool state to the Parser (just
> > using RAII object as before) struct B will trigger diagnostic error because
> > the state "ParsingOffsetof" is passed into inner declaration.
> GCC accepts currently: https://godbolt.org/z/oEvzjW6Ee but you're correct
> regarding switching back to an RAII object being an easier way to address the
> nested declarations.
>
> Let me think on this situation a bit....
> GCC accepts currently
C++: https://godbolt.org/z/fon8e7dzf
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D133574/new/
https://reviews.llvm.org/D133574
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