https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114181
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |MOVED
Status|WAITING |RESOLVED
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to g.peterhoff from comment #3)
> Of course issubnormal is defined in math.h (in my case line 1088, gcc 13.2).
libstdc++'s cmath does:
```
#define _GLIBCXX_INCLUDE_NEXT_C_HEADERS
#include_next <math.h>
#undef _GLIBCXX_INCLUDE_NEXT_C_HEADERS
...
#undef fpclassify
#undef isfinite
#undef isinf
#undef isnan
#undef isnormal
#undef signbit
#undef isgreater
#undef isgreaterequal
#undef isless
#undef islessequal
#undef islessgreater
#undef isunordered
```
And then libstdc++'s math.h does:
```
#if !defined __cplusplus || defined _GLIBCXX_INCLUDE_NEXT_C_HEADERS
# include_next <math.h>
#else
#ifndef _GLIBCXX_MATH_H
#define _GLIBCXX_MATH_H 1
# include <cmath>
```
If you are implementing a cmath for a C++ implementation, you need to a similar
thing and `#undef` it.
The math.h that defines issubnormal comes from glibc.
