[Bug libgomp/90527] alloc.c:72:7: error: implicit declaration of function ‘posix_memalign’

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90527

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
libgomp configure checks for posix_memalign:
AC_CHECK_FUNCS(aligned_alloc posix_memalign memalign _aligned_malloc)
and uses posix_memalign only if it is found:
#ifdef HAVE_ALIGNED_ALLOC
  ret = aligned_alloc (al, size);
#elif defined(HAVE__ALIGNED_MALLOC)
  ret = _aligned_malloc (size, al);
#elif defined(HAVE_POSIX_MEMALIGN)
  if (posix_memalign (&ret, al, size) != 0)
    ret = NULL;
#elif defined(HAVE_MEMALIGN)
  {
    extern void *memalign (size_t, size_t);
    ret = memalign (al, size);
  }
#else
So your case seems to be that posix_memalign is present in the library, but not
declared, I think AC_CHECK_FUNCS just checks whether it is defined in the
library.  So, either we need additionally AC_CHECK_DECL for posix_memalign, or
for this case perhaps #define _GNU_SOURCE before first header in alloc.c might
be enough, in env.c we already do that.
So, can you try:
--- libgomp/alloc.c     2019-04-25 20:01:50.766232432 +0200
+++ libgomp/alloc.c     2019-05-18 10:10:40.153245345 +0200
@@ -27,6 +27,7 @@
    places in the OpenMP API do not make any provision for failure, so in
    general we cannot allow memory allocation to fail.  */

+#define _GNU_SOURCE
 #include "libgomp.h"
 #include <stdlib.h>