# environ.m4 serial 6

dnl Copyright (C) 2001-2004, 2006-2017 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.

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])

  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

])

# Check if a variable is properly declared.

# gt_CHECK_VAR_DECL(includes,variable)

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_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,

              [Define if you have the declaration of $2.])

  fi

  undefine([gt_cv_var])

])