[PATCH] Undef __INT64_C/__UINT64_C for glibc build and test

[H.J. Lu]

On Fri, Aug 22, 2025 at 4:37 PM Collin Funk <collin.funk1@gmail.com> wrote:
>
> "H.J. Lu" <hjl.tools@gmail.com> writes:
>
> > Since clang 20 defines __INT64_C and __UINT64_C as built-in macros, undef
> > them for glibc build and test.  This fixes BZ #33311.
> >
> > Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
> > ---
> >  include/stdint.h | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/include/stdint.h b/include/stdint.h
> > index 7f428741d7..8db6187c49 100644
> > --- a/include/stdint.h
> > +++ b/include/stdint.h
> > @@ -1 +1,6 @@
> > +#ifndef _STDINT_H
> > +/* NB: Clang 20 defines them as built-in macros.  */
> > +#undef __INT64_C
> > +#undef __UINT64_C
> >  #include <stdlib/stdint.h>
> > +#endif
>
> Should we just do all the others while we are at it? They are also

Since stdint.h defines only __INT64_C and __UINT64_C, we don't
need to do more than that.

> defined [1]. Confirmed on my system:
>
> $ echo | clang -dM -E - | grep -F '_C('
> #define __INT16_C(c) c
> #define __INT32_C(c) c
> #define __INT64_C(c) c##L
> #define __INT8_C(c) c
> #define __INTMAX_C(c) c##L
> #define __UINT16_C(c) c
> #define __UINT32_C(c) c##U
> #define __UINT64_C(c) c##UL
> #define __UINT8_C(c) c
> #define __UINTMAX_C(c) c##UL
>
> Collin
>
> [1] https://github.com/llvm/llvm-project/commit/33ad474c45e6d7a0de7bc75e15e27cf6cb9ff895



-- 
H.J.