openpbs/m4/pbs_decl_h_errno.m4

# Copyright (C) 1994-2018 Altair Engineering, Inc.
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# Test to see whether h_errno is visible when netdb.h is included.
# At least under HP-UX 10.x this is not the case unless
# XOPEN_SOURCE_EXTENDED is declared but then other nasty stuff happens.
# The appropriate thing to do is to call this macro and then
# if it is not available do a "extern int h_errno;" in the code.

AC_DEFUN([PBS_AC_DECL_H_ERRNO],
  [AC_CACHE_CHECK([for h_errno declaration in netdb.h],
    ac_cv_decl_h_errno,
    [AC_TRY_COMPILE([#include <sys/types.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <netdb.h>
],
      [int _ZzQ = (int)(h_errno + 1);],
      [ac_cv_decl_h_errno=yes],
      [ac_cv_decl_h_errno=no])
    ])
  AS_IF([test x$ac_cv_decl_h_errno = xyes],
    AC_DEFINE(H_ERRNO_DECLARED, [], [Defined when h_errno is declared in netdb.h]))
])