Merge from gnulib, using build-aux to remove clutter.

* m4/largefile.m4: New file, so that Emacs does not mess up when
accessing files with large inode numbers in MacOS X 10.5 and later.
* m4/nocrash.m4: New file, to avoid triggering background debugger
and/or create core dumps during 'configure'.
* build-aux/move-if-change: Renamed from move-if-change.
* build-aux/snippet/arg-nonnull.h: Renamed from arg-nonnull.h.
* build-aux/snippet/c++defs.h: Renamed from c++defs.h.
* build-aux/snippet/warn-on-use.h: Renamed from warn-on-use.h.
* build-aux/snippet/_Noreturn.h: New file, for draft C1X _Noreturn.
* .bzrignore: The autogenerated files compile, config.guess,
config.sub, depcomp, install-sh, and missing are now in build-aux.
* Makefile.in (epaths-force, sync-from-gnulib):
move-if-change is now in build-aux.
(GNULIB_TOOL_FLAGS): Avoid threadlib; this is now a prerequisite
of gnulib's pthread_sigmask module, but Emacs doesn't need it.
(mkdir): install-sh is now in build-aux.
* config.bat: c++defs.h is now in build-aux/snippets.
* configure.in: Specify AC_CONFIG_AUX_DIR with build-aux (the
usual parameter).
* lib/gnulib.mk, m4/gl-comp.m4: Regenerate.
* lib/makefile.w32-in (ARG_NONNULL_H): arg-nonnull.h moved
to build-aux/snippet.
* lib/pthread_sigmask.c, lib/stdlib.in.h, m4/extensions.m4:
* m4/getopt.m4, m4/gnulib-common.m4, m4/pthread_sigmask.m4:
Merge from gnuilib.  This fixes porting bugs on Cygwin, Irix, and
Solaris, enables MacOS extensions, and enables nocrash during
'configure'.
* make-dist: Adjust to new build-aux and build-aux/snippit dirs.
* admin/notes/copyright: The files compile, config.guess, config.sub,
depcomp, install-sh, missing, and move-if-change are now in the
new build-aux subdirectory.  The files arg-nonnull.h, c++defs.h,
and warn-on-use.h are now in build-aux/snippets.  New file
build-aux/snippets/_Noreturn.h.
* leim/Makefile.in (install): install-sh is now in build-aux.
* lib-src/Makefile.in ($(DESTDIR)${archlibdir}): install-sh moved
to build-aux.
* msdos/sedlibmk.inp (CONFIG_CLEAN_VPATH_FILES): Adjust to snippet moves
from top level to build-aux/snippet.
* src/Makefile.in (gl-stamp): move-if-change is now in build-aux.

5 files changed, 499 insertions, 0 deletions

diff --git a/build-aux/move-if-change b/build-aux/move-if-change
new file mode 100755
index 00000000000..e7ba25e3127
--- /dev/null
+++ b/build-aux/move-if-change
@@ -0,0 +1,83 @@
+#!/bin/sh
+# Like mv $1 $2, but if the files are the same, just delete $1.
+# Status is zero if successful, nonzero otherwise.
+
+VERSION='2011-01-28 20:09'; # UTC
+# The definition above must lie within the first 8 lines in order
+# for the Emacs time-stamp write hook (at end) to update it.
+# If you change this file with Emacs, please let the write hook
+# do its job.  Otherwise, update this string manually.
+
+# Copyright (C) 2002-2007, 2009-2011 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+usage="usage: $0 SOURCE DEST"
+
+help="$usage
+  or:  $0 OPTION
+If SOURCE is different than DEST, then move it to DEST; else remove SOURCE.
+
+  --help     display this help and exit
+  --version  output version information and exit
+
+The variable CMPPROG can be used to specify an alternative to \`cmp'.
+
+Report bugs to <bug-gnulib@gnu.org>."
+
+version=`expr "$VERSION" : '\([^ ]*\)'`
+version="move-if-change (gnulib) $version
+Copyright (C) 2011 Free Software Foundation, Inc.
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law."
+
+cmpprog=${CMPPROG-cmp}
+
+for arg
+do
+  case $arg in
+    --help | --hel | --he | --h)
+      exec echo "$help" ;;
+    --version | --versio | --versi | --vers | --ver | --ve | --v)
+      exec echo "$version" ;;
+    --)
+      shift
+      break ;;
+    -*)
+      echo "$0: invalid option: $arg" >&2
+      exit 1 ;;
+    *)
+      break ;;
+  esac
+done
+
+test $# -eq 2 || { echo "$0: $usage" >&2; exit 1; }
+
+if test -r "$2" && $cmpprog -- "$1" "$2" >/dev/null; then
+  rm -f -- "$1"
+else
+  if mv -f -- "$1" "$2"; then :; else
+    # Ignore failure due to a concurrent move-if-change.
+    test -r "$2" && $cmpprog -- "$1" "$2" >/dev/null && rm -f -- "$1"
+  fi
+fi
+
+## Local Variables:
+## eval: (add-hook 'write-file-hooks 'time-stamp)
+## time-stamp-start: "VERSION='"
+## time-stamp-format: "%:y-%02m-%02d %02H:%02M"
+## time-stamp-time-zone: "UTC"
+## time-stamp-end: "'; # UTC"
+## End:
diff --git a/build-aux/snippet/_Noreturn.h b/build-aux/snippet/_Noreturn.h
new file mode 100644
index 00000000000..1a7b4daed0a
--- /dev/null
+++ b/build-aux/snippet/_Noreturn.h
@@ -0,0 +1,10 @@
+#ifndef _Noreturn
+# if (3 <= __GNUC__ || (__GNUC__ == 2 && 8 <= __GNUC_MINOR__) \
+      || 0x5110 <= __SUNPRO_C)
+#  define _Noreturn __attribute__ ((__noreturn__))
+# elif 1200 <= _MSC_VER
+#  define _Noreturn __declspec (noreturn)
+# else
+#  define _Noreturn
+# endif
+#endif
diff --git a/build-aux/snippet/arg-nonnull.h b/build-aux/snippet/arg-nonnull.h
new file mode 100644
index 00000000000..6c2f1e82d06
--- /dev/null
+++ b/build-aux/snippet/arg-nonnull.h
@@ -0,0 +1,26 @@
+/* A C macro for declaring that specific arguments must not be NULL.
+   Copyright (C) 2009-2011 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* _GL_ARG_NONNULL((n,...,m)) tells the compiler and static analyzer tools
+   that the values passed as arguments n, ..., m must be non-NULL pointers.
+   n = 1 stands for the first argument, n = 2 for the second argument etc.  */
+#ifndef _GL_ARG_NONNULL
+# if (__GNUC__ == 3 && __GNUC_MINOR__ >= 3) || __GNUC__ > 3
+#  define _GL_ARG_NONNULL(params) __attribute__ ((__nonnull__ params))
+# else
+#  define _GL_ARG_NONNULL(params)
+# endif
+#endif
diff --git a/build-aux/snippet/c++defs.h b/build-aux/snippet/c++defs.h
new file mode 100644
index 00000000000..b6821a64ac4
--- /dev/null
+++ b/build-aux/snippet/c++defs.h
@@ -0,0 +1,271 @@
+/* C++ compatible function declaration macros.
+   Copyright (C) 2010-2011 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef _GL_CXXDEFS_H
+#define _GL_CXXDEFS_H
+
+/* The three most frequent use cases of these macros are:
+
+   * For providing a substitute for a function that is missing on some
+     platforms, but is declared and works fine on the platforms on which
+     it exists:
+
+       #if @GNULIB_FOO@
+       # if !@HAVE_FOO@
+       _GL_FUNCDECL_SYS (foo, ...);
+       # endif
+       _GL_CXXALIAS_SYS (foo, ...);
+       _GL_CXXALIASWARN (foo);
+       #elif defined GNULIB_POSIXCHECK
+       ...
+       #endif
+
+   * For providing a replacement for a function that exists on all platforms,
+     but is broken/insufficient and needs to be replaced on some platforms:
+
+       #if @GNULIB_FOO@
+       # if @REPLACE_FOO@
+       #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+       #   undef foo
+       #   define foo rpl_foo
+       #  endif
+       _GL_FUNCDECL_RPL (foo, ...);
+       _GL_CXXALIAS_RPL (foo, ...);
+       # else
+       _GL_CXXALIAS_SYS (foo, ...);
+       # endif
+       _GL_CXXALIASWARN (foo);
+       #elif defined GNULIB_POSIXCHECK
+       ...
+       #endif
+
+   * For providing a replacement for a function that exists on some platforms
+     but is broken/insufficient and needs to be replaced on some of them and
+     is additionally either missing or undeclared on some other platforms:
+
+       #if @GNULIB_FOO@
+       # if @REPLACE_FOO@
+       #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+       #   undef foo
+       #   define foo rpl_foo
+       #  endif
+       _GL_FUNCDECL_RPL (foo, ...);
+       _GL_CXXALIAS_RPL (foo, ...);
+       # else
+       #  if !@HAVE_FOO@   or   if !@HAVE_DECL_FOO@
+       _GL_FUNCDECL_SYS (foo, ...);
+       #  endif
+       _GL_CXXALIAS_SYS (foo, ...);
+       # endif
+       _GL_CXXALIASWARN (foo);
+       #elif defined GNULIB_POSIXCHECK
+       ...
+       #endif
+*/
+
+/* _GL_EXTERN_C declaration;
+   performs the declaration with C linkage.  */
+#if defined __cplusplus
+# define _GL_EXTERN_C extern "C"
+#else
+# define _GL_EXTERN_C extern
+#endif
+
+/* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes);
+   declares a replacement function, named rpl_func, with the given prototype,
+   consisting of return type, parameters, and attributes.
+   Example:
+     _GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...)
+                                  _GL_ARG_NONNULL ((1)));
+ */
+#define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \
+  _GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes)
+#define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \
+  _GL_EXTERN_C rettype rpl_func parameters_and_attributes
+
+/* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes);
+   declares the system function, named func, with the given prototype,
+   consisting of return type, parameters, and attributes.
+   Example:
+     _GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...)
+                                  _GL_ARG_NONNULL ((1)));
+ */
+#define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \
+  _GL_EXTERN_C rettype func parameters_and_attributes
+
+/* _GL_CXXALIAS_RPL (func, rettype, parameters);
+   declares a C++ alias called GNULIB_NAMESPACE::func
+   that redirects to rpl_func, if GNULIB_NAMESPACE is defined.
+   Example:
+     _GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...));
+ */
+#define _GL_CXXALIAS_RPL(func,rettype,parameters) \
+  _GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters)
+#if defined __cplusplus && defined GNULIB_NAMESPACE
+# define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
+    namespace GNULIB_NAMESPACE                                \
+    {                                                         \
+      rettype (*const func) parameters = ::rpl_func;          \
+    }                                                         \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#else
+# define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#endif
+
+/* _GL_CXXALIAS_RPL_CAST_1 (func, rpl_func, rettype, parameters);
+   is like  _GL_CXXALIAS_RPL_1 (func, rpl_func, rettype, parameters);
+   except that the C function rpl_func may have a slightly different
+   declaration.  A cast is used to silence the "invalid conversion" error
+   that would otherwise occur.  */
+#if defined __cplusplus && defined GNULIB_NAMESPACE
+# define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
+    namespace GNULIB_NAMESPACE                                     \
+    {                                                              \
+      rettype (*const func) parameters =                           \
+        reinterpret_cast<rettype(*)parameters>(::rpl_func);        \
+    }                                                              \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#else
+# define _GL_CXXALIAS_RPL_CAST_1(func,rpl_func,rettype,parameters) \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#endif
+
+/* _GL_CXXALIAS_SYS (func, rettype, parameters);
+   declares a C++ alias called GNULIB_NAMESPACE::func
+   that redirects to the system provided function func, if GNULIB_NAMESPACE
+   is defined.
+   Example:
+     _GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
+ */
+#if defined __cplusplus && defined GNULIB_NAMESPACE
+  /* If we were to write
+       rettype (*const func) parameters = ::func;
+     like above in _GL_CXXALIAS_RPL_1, the compiler could optimize calls
+     better (remove an indirection through a 'static' pointer variable),
+     but then the _GL_CXXALIASWARN macro below would cause a warning not only
+     for uses of ::func but also for uses of GNULIB_NAMESPACE::func.  */
+# define _GL_CXXALIAS_SYS(func,rettype,parameters) \
+    namespace GNULIB_NAMESPACE                     \
+    {                                              \
+      static rettype (*func) parameters = ::func;  \
+    }                                              \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#else
+# define _GL_CXXALIAS_SYS(func,rettype,parameters) \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#endif
+
+/* _GL_CXXALIAS_SYS_CAST (func, rettype, parameters);
+   is like  _GL_CXXALIAS_SYS (func, rettype, parameters);
+   except that the C function func may have a slightly different declaration.
+   A cast is used to silence the "invalid conversion" error that would
+   otherwise occur.  */
+#if defined __cplusplus && defined GNULIB_NAMESPACE
+# define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
+    namespace GNULIB_NAMESPACE                          \
+    {                                                   \
+      static rettype (*func) parameters =               \
+        reinterpret_cast<rettype(*)parameters>(::func); \
+    }                                                   \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#else
+# define _GL_CXXALIAS_SYS_CAST(func,rettype,parameters) \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#endif
+
+/* _GL_CXXALIAS_SYS_CAST2 (func, rettype, parameters, rettype2, parameters2);
+   is like  _GL_CXXALIAS_SYS (func, rettype, parameters);
+   except that the C function is picked among a set of overloaded functions,
+   namely the one with rettype2 and parameters2.  Two consecutive casts
+   are used to silence the "cannot find a match" and "invalid conversion"
+   errors that would otherwise occur.  */
+#if defined __cplusplus && defined GNULIB_NAMESPACE
+  /* The outer cast must be a reinterpret_cast.
+     The inner cast: When the function is defined as a set of overloaded
+     functions, it works as a static_cast<>, choosing the designated variant.
+     When the function is defined as a single variant, it works as a
+     reinterpret_cast<>. The parenthesized cast syntax works both ways.  */
+# define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
+    namespace GNULIB_NAMESPACE                                                \
+    {                                                                         \
+      static rettype (*func) parameters =                                     \
+        reinterpret_cast<rettype(*)parameters>(                               \
+          (rettype2(*)parameters2)(::func));                                  \
+    }                                                                         \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#else
+# define _GL_CXXALIAS_SYS_CAST2(func,rettype,parameters,rettype2,parameters2) \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#endif
+
+/* _GL_CXXALIASWARN (func);
+   causes a warning to be emitted when ::func is used but not when
+   GNULIB_NAMESPACE::func is used.  func must be defined without overloaded
+   variants.  */
+#if defined __cplusplus && defined GNULIB_NAMESPACE
+# define _GL_CXXALIASWARN(func) \
+   _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
+# define _GL_CXXALIASWARN_1(func,namespace) \
+   _GL_CXXALIASWARN_2 (func, namespace)
+/* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
+   we enable the warning only when not optimizing.  */
+# if !__OPTIMIZE__
+#  define _GL_CXXALIASWARN_2(func,namespace) \
+    _GL_WARN_ON_USE (func, \
+                     "The symbol ::" #func " refers to the system function. " \
+                     "Use " #namespace "::" #func " instead.")
+# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
+#  define _GL_CXXALIASWARN_2(func,namespace) \
+     extern __typeof__ (func) func
+# else
+#  define _GL_CXXALIASWARN_2(func,namespace) \
+     _GL_EXTERN_C int _gl_cxxalias_dummy
+# endif
+#else
+# define _GL_CXXALIASWARN(func) \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#endif
+
+/* _GL_CXXALIASWARN1 (func, rettype, parameters_and_attributes);
+   causes a warning to be emitted when the given overloaded variant of ::func
+   is used but not when GNULIB_NAMESPACE::func is used.  */
+#if defined __cplusplus && defined GNULIB_NAMESPACE
+# define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
+   _GL_CXXALIASWARN1_1 (func, rettype, parameters_and_attributes, \
+                        GNULIB_NAMESPACE)
+# define _GL_CXXALIASWARN1_1(func,rettype,parameters_and_attributes,namespace) \
+   _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)
+/* To work around GCC bug <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
+   we enable the warning only when not optimizing.  */
+# if !__OPTIMIZE__
+#  define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
+    _GL_WARN_ON_USE_CXX (func, rettype, parameters_and_attributes, \
+                         "The symbol ::" #func " refers to the system function. " \
+                         "Use " #namespace "::" #func " instead.")
+# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
+#  define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
+     extern __typeof__ (func) func
+# else
+#  define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
+     _GL_EXTERN_C int _gl_cxxalias_dummy
+# endif
+#else
+# define _GL_CXXALIASWARN1(func,rettype,parameters_and_attributes) \
+    _GL_EXTERN_C int _gl_cxxalias_dummy
+#endif
+
+#endif /* _GL_CXXDEFS_H */
diff --git a/build-aux/snippet/warn-on-use.h b/build-aux/snippet/warn-on-use.h
new file mode 100644
index 00000000000..2cdeec3e663
--- /dev/null
+++ b/build-aux/snippet/warn-on-use.h
@@ -0,0 +1,109 @@
+/* A C macro for emitting warnings if a function is used.
+   Copyright (C) 2010-2011 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* _GL_WARN_ON_USE (function, "literal string") issues a declaration
+   for FUNCTION which will then trigger a compiler warning containing
+   the text of "literal string" anywhere that function is called, if
+   supported by the compiler.  If the compiler does not support this
+   feature, the macro expands to an unused extern declaration.
+
+   This macro is useful for marking a function as a potential
+   portability trap, with the intent that "literal string" include
+   instructions on the replacement function that should be used
+   instead.  However, one of the reasons that a function is a
+   portability trap is if it has the wrong signature.  Declaring
+   FUNCTION with a different signature in C is a compilation error, so
+   this macro must use the same type as any existing declaration so
+   that programs that avoid the problematic FUNCTION do not fail to
+   compile merely because they included a header that poisoned the
+   function.  But this implies that _GL_WARN_ON_USE is only safe to
+   use if FUNCTION is known to already have a declaration.  Use of
+   this macro implies that there must not be any other macro hiding
+   the declaration of FUNCTION; but undefining FUNCTION first is part
+   of the poisoning process anyway (although for symbols that are
+   provided only via a macro, the result is a compilation error rather
+   than a warning containing "literal string").  Also note that in
+   C++, it is only safe to use if FUNCTION has no overloads.
+
+   For an example, it is possible to poison 'getline' by:
+   - adding a call to gl_WARN_ON_USE_PREPARE([[#include <stdio.h>]],
+     [getline]) in configure.ac, which potentially defines
+     HAVE_RAW_DECL_GETLINE
+   - adding this code to a header that wraps the system <stdio.h>:
+     #undef getline
+     #if HAVE_RAW_DECL_GETLINE
+     _GL_WARN_ON_USE (getline, "getline is required by POSIX 2008, but"
+       "not universally present; use the gnulib module getline");
+     #endif
+
+   It is not possible to directly poison global variables.  But it is
+   possible to write a wrapper accessor function, and poison that
+   (less common usage, like &environ, will cause a compilation error
+   rather than issue the nice warning, but the end result of informing
+   the developer about their portability problem is still achieved):
+   #if HAVE_RAW_DECL_ENVIRON
+   static inline char ***rpl_environ (void) { return &environ; }
+   _GL_WARN_ON_USE (rpl_environ, "environ is not always properly declared");
+   # undef environ
+   # define environ (*rpl_environ ())
+   #endif
+   */
+#ifndef _GL_WARN_ON_USE
+
+# if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__)
+/* A compiler attribute is available in gcc versions 4.3.0 and later.  */
+#  define _GL_WARN_ON_USE(function, message) \
+extern __typeof__ (function) function __attribute__ ((__warning__ (message)))
+# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
+/* Verify the existence of the function.  */
+#  define _GL_WARN_ON_USE(function, message) \
+extern __typeof__ (function) function
+# else /* Unsupported.  */
+#  define _GL_WARN_ON_USE(function, message) \
+_GL_WARN_EXTERN_C int _gl_warn_on_use
+# endif
+#endif
+
+/* _GL_WARN_ON_USE_CXX (function, rettype, parameters_and_attributes, "string")
+   is like _GL_WARN_ON_USE (function, "string"), except that the function is
+   declared with the given prototype, consisting of return type, parameters,
+   and attributes.
+   This variant is useful for overloaded functions in C++. _GL_WARN_ON_USE does
+   not work in this case.  */
+#ifndef _GL_WARN_ON_USE_CXX
+# if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__)
+#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
+extern rettype function parameters_and_attributes \
+     __attribute__ ((__warning__ (msg)))
+# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
+/* Verify the existence of the function.  */
+#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
+extern rettype function parameters_and_attributes
+# else /* Unsupported.  */
+#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
+_GL_WARN_EXTERN_C int _gl_warn_on_use
+# endif
+#endif
+
+/* _GL_WARN_EXTERN_C declaration;
+   performs the declaration with C linkage.  */
+#ifndef _GL_WARN_EXTERN_C
+# if defined __cplusplus
+#  define _GL_WARN_EXTERN_C extern "C"
+# else
+#  define _GL_WARN_EXTERN_C extern
+# endif
+#endif