1# environ.m4 serial 7
2dnl Copyright (C) 2001-2004, 2006-2019 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
13  AC_CHECK_HEADERS_ONCE([unistd.h])
14  gt_CHECK_VAR_DECL(
15    [#if HAVE_UNISTD_H
16     #include <unistd.h>
17     #endif
18     /* mingw, BeOS, Haiku declare environ in <stdlib.h>, not in <unistd.h>.  */
19     #include <stdlib.h>
20    ],
21    [environ])
22  if test $gt_cv_var_environ_declaration != yes; then
23    HAVE_DECL_ENVIRON=0
24  fi
25])
26
27# Check if a variable is properly declared.
28# gt_CHECK_VAR_DECL(includes,variable)
29AC_DEFUN([gt_CHECK_VAR_DECL],
30[
31  define([gt_cv_var], [gt_cv_var_]$2[_declaration])
32  AC_CACHE_CHECK([if $2 is properly declared], [gt_cv_var],
33    [AC_COMPILE_IFELSE(
34       [AC_LANG_PROGRAM(
35          [[$1
36            extern struct { int foo; } $2;]],
37          [[$2.foo = 1;]])],
38       [gt_cv_var=no],
39       [gt_cv_var=yes])])
40  if test $gt_cv_var = yes; then
41    AC_DEFINE([HAVE_]m4_translit($2, [a-z], [A-Z])[_DECL], 1,
42              [Define if you have the declaration of $2.])
43  fi
44  undefine([gt_cv_var])
45])
46