1# environ.m4 serial 5
2dnl Copyright (C) 2001-2004, 2006-2011 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7AC_DEFUN_ONCE([gl_ENVIRON],
8[
9  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
10  dnl Persuade glibc <unistd.h> to declare environ.
11  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
12  gt_CHECK_VAR_DECL([#include <unistd.h>], environ)
13  if test $gt_cv_var_environ_declaration != yes; then
14    HAVE_DECL_ENVIRON=0
15  fi
16])
17
18# Check if a variable is properly declared.
19# gt_CHECK_VAR_DECL(includes,variable)
20AC_DEFUN([gt_CHECK_VAR_DECL],
21[
22  define([gt_cv_var], [gt_cv_var_]$2[_declaration])
23  AC_MSG_CHECKING([if $2 is properly declared])
24  AC_CACHE_VAL([gt_cv_var], [
25    AC_COMPILE_IFELSE(
26      [AC_LANG_PROGRAM(
27         [[$1
28           extern struct { int foo; } $2;]],
29         [[$2.foo = 1;]])],
30      [gt_cv_var=no],
31      [gt_cv_var=yes])])
32  AC_MSG_RESULT([$gt_cv_var])
33  if test $gt_cv_var = yes; then
34    AC_DEFINE([HAVE_]m4_translit($2, [a-z], [A-Z])[_DECL], 1,
35              [Define if you have the declaration of $2.])
36  fi
37  undefine([gt_cv_var])
38])
39