1 files changed, 19 insertions, 8 deletions

diff --git a/gl/m4/environ.m4 b/gl/m4/environ.m4
index 4c6849a3..593a33ed 100644
--- a/gl/m4/environ.m4
+++ b/gl/m4/environ.m4
@@ -1,5 +1,5 @@
-# environ.m4 serial 4
-dnl Copyright (C) 2001-2004, 2006-2010 Free Software Foundation, Inc.
+# environ.m4 serial 6
+dnl Copyright (C) 2001-2004, 2006-2013 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -9,7 +9,16 @@ AC_DEFUN_ONCE([gl_ENVIRON],
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   dnl Persuade glibc <unistd.h> to declare environ.
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
-  gt_CHECK_VAR_DECL([#include <unistd.h>], environ)
+
+  AC_CHECK_HEADERS_ONCE([unistd.h])
+  gt_CHECK_VAR_DECL(
+    [#if HAVE_UNISTD_H
+     #include <unistd.h>
+     #endif
+     /* mingw, BeOS, Haiku declare environ in <stdlib.h>, not in <unistd.h>.  */
+     #include <stdlib.h>
+    ],
+    [environ])
   if test $gt_cv_var_environ_declaration != yes; then
     HAVE_DECL_ENVIRON=0
   fi
@@ -22,11 +31,13 @@ AC_DEFUN([gt_CHECK_VAR_DECL],
   define([gt_cv_var], [gt_cv_var_]$2[_declaration])
   AC_MSG_CHECKING([if $2 is properly declared])
   AC_CACHE_VAL([gt_cv_var], [
-    AC_TRY_COMPILE([$1
-      extern struct { int foo; } $2;],
-      [$2.foo = 1;],
-      gt_cv_var=no,
-      gt_cv_var=yes)])
+    AC_COMPILE_IFELSE(
+      [AC_LANG_PROGRAM(
+         [[$1
+           extern struct { int foo; } $2;]],
+         [[$2.foo = 1;]])],
+      [gt_cv_var=no],
+      [gt_cv_var=yes])])
   AC_MSG_RESULT([$gt_cv_var])
   if test $gt_cv_var = yes; then
     AC_DEFINE([HAVE_]m4_translit($2, [a-z], [A-Z])[_DECL], 1,