Thanks for catching those glitches. I suppose you're right, the new
_GL_ATTRIBUTE_* macros should be in gnulib-common.m4 even though that will now
grow by a bit (meaning config.h will grow quite a bit). Attached is a revised
draft patch to Gnulib, which (unlike the previous one) I have tested a bit. It
doesn't attempt to revamp all of Gnulib to use the new macros, but does enough
of them to give a flavor for the conversion.
>From 678e75be630f012a097092e781f9eac0eaa2c679 Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Fri, 1 May 2020 18:12:12 -0700
Subject: [PATCH] attribute: new module
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This simplifies use of GCC and C2X attributes like ‘deprecated’.
* MODULES.html.sh: Add attribute.
* doc/attribute.texi, lib/attribute.h, modules/attribute: New files.
* doc/gnulib.texi (Particular Modules): Add Attributes.
* lib/backupfile.c, lib/fnmatch.c, lib/freopen-safer.c:
* lib/mbrtoc32.c, lib/mbrtowc.c, lib/nstrftime.c, lib/quotearg.c:
* lib/savewd.c, lib/unistr/u8-uctomb-aux.c, lib/unistr/u8-uctomb.c:
* lib/vasnprintf.c:
Include attribute.h, and let it define FALLTHROUGH.
* lib/bitset/base.h, lib/c-stack.c (__attribute__): Remove macro.
* lib/bitset/base.h (ATTRIBUTE_UNUSED): Define in terms of
_GL_ATTRIBUTE_MAYBE_UNUSED, for forwards compatibility to C2X.
* lib/dfa.c (FALLTHROUGH): Define consistently with gl_COMMON_BODY.
This is a copy since Gawk doesn’t use Gnulib.
* lib/di-set.h (_GL_ATTRIBUTE_NONNULL): Remove definition that
is incompatible with gl_COMMON_BODY’s.  All uses changed.
* lib/fts.c: Include attribte.h, for FALLTHROUGH.
Keep the existing FALLTHROUGH definition since Glibc might use it,
and it does no harm to Gnulib’s FALLTHROUGH.
* lib/fts_.h, lib/inttostr.h:
(__GNUC_PREREQ): Remove; no longer needed.
(__attribute_warn_unused_result__): Remove.  All uses
replaced by _GL_ATTRIBUTE_NODISCARD.
* lib/gl_list.h, lib/gl_map.h, lib/gl_omap.h, lib/gl_oset.h:
* lib/gl_set.h: Prefer _GL_ATTRIBUTE_NODISCARD to an ifdeffed
__attribute__ ((__warn_unused_result__)), for forward
compatibility to C2X.
* lib/hash.h (_GL_ATTRIBUTE_WUR): Remove.  All uses replaced by
_GL_ATTRIBUTE_NODISCARD.
(_GL_ATTRIBUTE_DEPRECATED): Remove, since gl_COMMON_BODY defines it.
* lib/ino-map.h (_GL_ATTRIBUTE_NONNULL): Remove.  All uses
replaced by gl_COMMON_BODY’s implementation, which has a
slightly different signature.
* lib/safe-alloc.h (_GL_ATTRIBUTE_RETURN_CHECK):
Remove.  All uses replaced by _GL_ATTRIBUTE_NODISCARD.
* lib/unused-parameter.h (_GL_UNUSED_PARAMETER):
Define in terms of _GL_ATTRIBUTE_MAYBE_UNUSED.
No doubt all uses should be replaced, at some point.
* m4/gnulib-common.m4 (_GL_GNUC_PREREQ): New macro.
(_Noreturn): Use it.
(_GL_HAS_ATTRIBUTE, _GL_ATTRIBUTE_ALLOC_SIZE)
(_GL_ATTRIBUTE_ALWAYS_INLINE, _GL_ATTRIBUTE_ARTIFICIAL)
(_GL_ATTRIBUTE_COLD)
(_GL_ATTRIBUTE_DEPRECATED, _GL_ATTRIBUTE_ERROR)
(_GL_ATTRIBUTE_WARNING, _GL_ATTRIBUTE_EXTERNALLY_VISIBLE)
(_GL_ATTRIBUTE_FALLTHROUGH, _GL_ATTRIBUTE_FORMAT)
(_GL_ATTRIBUTE_LEAF, _GL_ATTRIBUTE_MAY_ALIAS)
(_GL_ATTRIBUTE_MAYBE_UNUSED)
(_GL_ATTRIBUTE_NODISCARD, _GL_ATTRIBUTE_NOINLINE)
(_GL_ATTRIBUTE_NONNULL, _GL_ATTRIBUTE_NONSTRING)
(_GL_ATTRIBUTE_NOTHROW, _GL_ATTRIBUTE_PACKED, _GL_ATTRIBUTE_PURE)
(_GL_ATTRIBUTE_SENTINEL): New macros.
* modules/backup-rename, modules/backupfile, modules/c-vasnprintf:
* modules/fnmatch, modules/freopen-safer, modules/fts:
* modules/mbrtoc32, modules/mbrtowc, modules/nstrftime:
* modules/quotearg, modules/savewd:
* modules/unistdio/u16-u16-vasnprintf:
* modules/unistdio/u16-vasnprintf:
* modules/unistdio/u32-u32-vasnprintf:
* modules/unistdio/u32-vasnprintf:
* modules/unistdio/u8-u8-vasnprintf:
* modules/unistdio/u8-vasnprintf:
* modules/unistdio/ulc-vasnprintf:
* modules/unistr/u8-uctomb, modules/vasnprintf:
(Depends-on:): Add attribute module.
---
 ChangeLog                           |  69 +++++++++
 MODULES.html.sh                     |   1 +
 doc/attribute.texi                  |  43 ++++++
 doc/gnulib.texi                     |   3 +
 lib/anytostr.c                      |   2 +-
 lib/attribute.h                     |  56 +++++++
 lib/backupfile.c                    |   9 +-
 lib/bitset/base.h                   |   8 +-
 lib/c-stack.c                       |   6 -
 lib/dfa.c                           |   4 +-
 lib/di-set.h                        |  13 +-
 lib/fnmatch.c                       |   9 +-
 lib/freopen-safer.c                 |  10 +-
 lib/fts.c                           |   1 +
 lib/fts_.h                          |  25 +---
 lib/gl_list.h                       |  80 ++--------
 lib/gl_map.h                        |  20 +--
 lib/gl_omap.h                       |  20 +--
 lib/gl_oset.h                       |  10 +-
 lib/gl_set.h                        |  10 +-
 lib/hash.h                          |  26 +---
 lib/ino-map.h                       |  11 +-
 lib/inttostr.h                      |  27 +---
 lib/mbrtoc32.c                      |  10 +-
 lib/mbrtowc.c                       |   9 +-
 lib/nstrftime.c                     |   9 +-
 lib/quotearg.c                      |   9 +-
 lib/safe-alloc.h                    |  12 +-
 lib/savewd.c                        |   9 +-
 lib/unistr/u8-uctomb-aux.c          |   8 +-
 lib/unistr/u8-uctomb.c              |   8 +-
 lib/unused-parameter.h              |   6 +-
 lib/vasnprintf.c                    |   9 +-
 m4/gnulib-common.m4                 | 223 ++++++++++++++++++++++++----
 modules/attribute                   |  19 +++
 modules/backup-rename               |   1 +
 modules/backupfile                  |   1 +
 modules/c-vasnprintf                |   1 +
 modules/fnmatch                     |   1 +
 modules/freopen-safer               |   1 +
 modules/fts                         |   1 +
 modules/mbrtoc32                    |   1 +
 modules/mbrtowc                     |   1 +
 modules/nstrftime                   |   1 +
 modules/quotearg                    |   1 +
 modules/savewd                      |   1 +
 modules/unistdio/u16-u16-vasnprintf |   1 +
 modules/unistdio/u16-vasnprintf     |   1 +
 modules/unistdio/u32-u32-vasnprintf |   1 +
 modules/unistdio/u32-vasnprintf     |   1 +
 modules/unistdio/u8-u8-vasnprintf   |   1 +
 modules/unistdio/u8-vasnprintf      |   1 +
 modules/unistdio/ulc-vasnprintf     |   1 +
 modules/unistr/u8-uctomb            |   1 +
 modules/vasnprintf                  |   1 +
 55 files changed, 471 insertions(+), 343 deletions(-)
 create mode 100644 doc/attribute.texi
 create mode 100644 lib/attribute.h
 create mode 100644 modules/attribute

diff --git a/ChangeLog b/ChangeLog
index 033f3be48..72c62be29 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,72 @@
+2020-05-02  Paul Eggert  <egg...@cs.ucla.edu>
+
+	attribute: new module
+	This simplifies use of GCC and C2X attributes like ‘deprecated’.
+	* MODULES.html.sh: Add attribute.
+	* doc/attribute.texi, lib/attribute.h, modules/attribute: New files.
+	* doc/gnulib.texi (Particular Modules): Add Attributes.
+	* lib/backupfile.c, lib/fnmatch.c, lib/freopen-safer.c:
+	* lib/mbrtoc32.c, lib/mbrtowc.c, lib/nstrftime.c, lib/quotearg.c:
+	* lib/savewd.c, lib/unistr/u8-uctomb-aux.c, lib/unistr/u8-uctomb.c:
+	* lib/vasnprintf.c:
+	Include attribute.h, and let it define FALLTHROUGH.
+	* lib/bitset/base.h, lib/c-stack.c (__attribute__): Remove macro.
+	* lib/bitset/base.h (ATTRIBUTE_UNUSED): Define in terms of
+	_GL_ATTRIBUTE_MAYBE_UNUSED, for forwards compatibility to C2X.
+	* lib/dfa.c (FALLTHROUGH): Define consistently with gl_COMMON_BODY.
+	This is a copy since Gawk doesn’t use Gnulib.
+	* lib/di-set.h (_GL_ATTRIBUTE_NONNULL): Remove definition that
+	is incompatible with gl_COMMON_BODY’s.  All uses changed.
+	* lib/fts.c: Include attribte.h, for FALLTHROUGH.
+	Keep the existing FALLTHROUGH definition since Glibc might use it,
+	and it does no harm to Gnulib’s FALLTHROUGH.
+	* lib/fts_.h, lib/inttostr.h:
+	(__GNUC_PREREQ): Remove; no longer needed.
+	(__attribute_warn_unused_result__): Remove.  All uses
+	replaced by _GL_ATTRIBUTE_NODISCARD.
+	* lib/gl_list.h, lib/gl_map.h, lib/gl_omap.h, lib/gl_oset.h:
+	* lib/gl_set.h: Prefer _GL_ATTRIBUTE_NODISCARD to an ifdeffed
+	__attribute__ ((__warn_unused_result__)), for forward
+	compatibility to C2X.
+	* lib/hash.h (_GL_ATTRIBUTE_WUR): Remove.  All uses replaced by
+	_GL_ATTRIBUTE_NODISCARD.
+	(_GL_ATTRIBUTE_DEPRECATED): Remove, since gl_COMMON_BODY defines it.
+	* lib/ino-map.h (_GL_ATTRIBUTE_NONNULL): Remove.  All uses
+	replaced by gl_COMMON_BODY’s implementation, which has a
+	slightly different signature.
+	* lib/safe-alloc.h (_GL_ATTRIBUTE_RETURN_CHECK):
+	Remove.  All uses replaced by _GL_ATTRIBUTE_NODISCARD.
+	* lib/unused-parameter.h (_GL_UNUSED_PARAMETER):
+	Define in terms of _GL_ATTRIBUTE_MAYBE_UNUSED.
+	No doubt all uses should be replaced, at some point.
+	* m4/gnulib-common.m4 (_GL_GNUC_PREREQ): New macro.
+	(_Noreturn): Use it.
+	(_GL_HAS_ATTRIBUTE, _GL_ATTRIBUTE_ALLOC_SIZE)
+	(_GL_ATTRIBUTE_ALWAYS_INLINE, _GL_ATTRIBUTE_ARTIFICIAL)
+	(_GL_ATTRIBUTE_COLD)
+	(_GL_ATTRIBUTE_DEPRECATED, _GL_ATTRIBUTE_ERROR)
+	(_GL_ATTRIBUTE_WARNING, _GL_ATTRIBUTE_EXTERNALLY_VISIBLE)
+	(_GL_ATTRIBUTE_FALLTHROUGH, _GL_ATTRIBUTE_FORMAT)
+	(_GL_ATTRIBUTE_LEAF, _GL_ATTRIBUTE_MAY_ALIAS)
+	(_GL_ATTRIBUTE_MAYBE_UNUSED)
+	(_GL_ATTRIBUTE_NODISCARD, _GL_ATTRIBUTE_NOINLINE)
+	(_GL_ATTRIBUTE_NONNULL, _GL_ATTRIBUTE_NONSTRING)
+	(_GL_ATTRIBUTE_NOTHROW, _GL_ATTRIBUTE_PACKED, _GL_ATTRIBUTE_PURE)
+	(_GL_ATTRIBUTE_SENTINEL): New macros.
+	* modules/backup-rename, modules/backupfile, modules/c-vasnprintf:
+	* modules/fnmatch, modules/freopen-safer, modules/fts:
+	* modules/mbrtoc32, modules/mbrtowc, modules/nstrftime:
+	* modules/quotearg, modules/savewd:
+	* modules/unistdio/u16-u16-vasnprintf:
+	* modules/unistdio/u16-vasnprintf:
+	* modules/unistdio/u32-u32-vasnprintf:
+	* modules/unistdio/u32-vasnprintf:
+	* modules/unistdio/u8-u8-vasnprintf:
+	* modules/unistdio/u8-vasnprintf:
+	* modules/unistdio/ulc-vasnprintf:
+	* modules/unistr/u8-uctomb, modules/vasnprintf:
+	(Depends-on:): Add attribute module.
+
 2020-05-01  Bruno Haible  <br...@clisp.org>
 
 	list: Add remove_first and remove_last operations.
diff --git a/MODULES.html.sh b/MODULES.html.sh
index 240a9ee20..318a15a1d 100755
--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -2364,6 +2364,7 @@ func_all_modules ()
   func_echo "$element"
 
   func_begin_table
+  func_module attribute
   func_module builtin-expect
   func_module ieee754-h
   func_module limits-h
diff --git a/doc/attribute.texi b/doc/attribute.texi
new file mode 100644
index 000000000..86591f16c
--- /dev/null
+++ b/doc/attribute.texi
@@ -0,0 +1,43 @@
+@c attribute module documentation
+
+@c Copyright 2020 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.3 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.  A
+@c copy of the license is at <https://www.gnu.org/licenses/fdl-1.3.en.html>.
+
+@node Attributes
+@section Attributes
+
+@cindex Attributes
+@findex __attribute__
+
+This module provides a header file @file{attribute.h} that defines
+macros related to C and C++ attributes and the GCC
+@code{__attribute__} keyword.
+
+Here is an example of its use:
+
+@example
+#include <attribute.h>
+
+extern char *crypt (char const *, char const *)
+  ATTRIBUTE_NOTHROW ATTRIBUTE_LEAF ATTRIBUTE_NONNULL ((1, 2));
+@end example
+
+@noindent
+@code{ATTRIBUTE_NOTHROW} expands to @code{__attribute__
+((__nothrow__))} if the compiler is a recent-enough GCC or GCC-like
+compiler, and to nothing otherwise.  Similarly for
+@code{ATTRIBUTE_LEAF}.  @code{ATTRIBUTE_NONNULL ((1, 2))} expands to
+@code{__attribute__ ((__nonnull__ (1, 2)))} if the compiler is
+recent-enough GCC, and to nothing otherwise.
+
+Most of these attribute names begin with @code{ATTRIBUTE_}.
+A few do not, because they are part of C2X and their
+names are not likely to clash with other macro names.
+These macros are @code{DEPRECATED}, @code{FALLTHROUGH},
+@code{MAYBE_UNUSED}, and @code{NODISCARD}, which can
+be defined to @code{[[deprecated]]} etc.@: on C2X platforms.
diff --git a/doc/gnulib.texi b/doc/gnulib.texi
index c9501ca23..3719978b6 100644
--- a/doc/gnulib.texi
+++ b/doc/gnulib.texi
@@ -6654,6 +6654,7 @@ to POSIX that it can be treated like any other Unix-like platform.
 * alloca::
 * alloca-opt::
 * Safe Allocation Macros::
+* Attributes::
 * Compile-time Assertions::
 * Non-returning Functions::
 * Integer Properties::
@@ -6685,6 +6686,8 @@ to POSIX that it can be treated like any other Unix-like platform.
 
 @include safe-alloc.texi
 
+@include attribute.texi
+
 @include verify.texi
 
 @include noreturn.texi
diff --git a/lib/anytostr.c b/lib/anytostr.c
index da602a7d7..5dcd211b4 100644
--- a/lib/anytostr.c
+++ b/lib/anytostr.c
@@ -32,7 +32,7 @@
    INT_BUFSIZE_BOUND (INTTYPE) bytes long.  Return the address of the
    printable string, which need not start at BUF.  */
 
-char * __attribute_warn_unused_result__
+char * _GL_ATTRIBUTE_NODISCARD
 anytostr (inttype i, char *buf)
 {
   char *p = buf + INT_STRLEN_BOUND (inttype);
diff --git a/lib/attribute.h b/lib/attribute.h
new file mode 100644
index 000000000..ffd9bdfa2
--- /dev/null
+++ b/lib/attribute.h
@@ -0,0 +1,56 @@
+/* ATTRIBUTE_* macros for using attributes in GCC and similar compilers
+
+   Copyright 2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify it
+   under the terms of the GNU Lesser 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert.  */
+
+/* Provide public ATTRIBUTE_* names for the private _GL_ATTRIBUTE_*
+   macros used within Gnulib.  */
+
+#ifndef _GL_ATTRIBUTE_H
+#define _GL_ATTRIBUTE_H
+
+/* C2X standard attributes have macro names that do not begin with
+   'ATTRIBUTE_'.  */
+#define DEPRECATED _GL_ATTRIBUTE_DEPRECATED
+#define FALLTHROUGH _GL_ATTRIBUTE_FALLTHROUGH
+#define MAYBE_UNUSED _GL_ATTRIBUTE_MAYBE_UNUSED
+#define NODISCARD _GL_ATTRIBUTE_NODISCARD
+
+/* Attributes from GCC have macro names beginning with 'ATTRIBUTE_' to
+   avoid name clashes.  */
+#define ATTRIBUTE_ALLOC_SIZE(args) _GL_ATTRIBUTE_ALLOC_SIZE(args)
+#define ATTRIBUTE_ALWAYS_INLINE _GL_ATTRIBUTE_ALWAYS_INLINE
+#define ATTRIBUTE_ARTIFICIAL _GL_ATTRIBUTE_ARTIFICIAL
+#define ATTRIBUTE_COLD _GL_ATTRIBUTE_COLD
+#define ATTRIBUTE_CONST _GL_ATTRIBUTE_CONST
+#define ATTRIBUTE_DEPRECATED _GL_ATTRIBUTE_DEPRECATED
+#define ATTRIBUTE_ERROR(msg) _GL_ATTRIBUTE_ERROR(msg)
+#define ATTRIBUTE_EXTERNALLY_VISIBLE _GL_ATTRIBUTE_EXTERNALLY_VISIBLE
+#define ATTRIBUTE_FORMAT(spec) _GL_ATTRIBUTE_FORMAT(spec)
+#define ATTRIBUTE_LEAF _GL_ATTRIBUTE_LEAF
+#define ATTRIBUTE_MAY_ALIAS _GL_ATTRIBUTE_MAY_ALIAS
+#define ATTRIBUTE_MALLOC _GL_ATTRIBUTE_MALLOC
+#define ATTRIBUTE_NOINLINE _GL_ATTRIBUTE_NOINLINE
+#define ATTRIBUTE_NONNULL(args) _GL_ATTRIBUTE_NONNULL(args)
+#define ATTRIBUTE_NONSTRING _GL_ATTRIBUTE_NONSTRING
+#define ATTRIBUTE_NOTHROW _GL_ATTRIBUTE_NOTHROW
+#define ATTRIBUTE_PACKED _GL_ATTRIBUTE_PACKED
+#define ATTRIBUTE_PURE _GL_ATTRIBUTE_PURE
+#define ATTRIBUTE_SENTINEL(pos) _GL_ATTRIBUTE_SENTINEL(pos)
+#define ATTRIBUTE_WARNING(msg) _GL_ATTRIBUTE_WARNING(msg)
+
+#endif /* _GL_ATTRIBUTE_H */
diff --git a/lib/backupfile.c b/lib/backupfile.c
index 319f084ef..7edd9c3db 100644
--- a/lib/backupfile.c
+++ b/lib/backupfile.c
@@ -22,6 +22,7 @@
 
 #include "backup-internal.h"
 
+#include "attribute.h"
 #include "dirname.h"
 #include "opendirat.h"
 #include "renameatu.h"
@@ -35,14 +36,6 @@
 #include <string.h>
 #include <unistd.h>
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
-
 #ifndef _D_EXACT_NAMLEN
 # define _D_EXACT_NAMLEN(dp) strlen ((dp)->d_name)
 #endif
diff --git a/lib/bitset/base.h b/lib/bitset/base.h
index 46ec894ec..1020515a4 100644
--- a/lib/bitset/base.h
+++ b/lib/bitset/base.h
@@ -27,13 +27,7 @@
 
 #include "xalloc.h"
 
-#ifndef __attribute__
-# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8)
-#  define __attribute__(x)
-# endif
-#endif
-
-#define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
+#define ATTRIBUTE_UNUSED _GL_ATTRIBUTE_MAYBE_UNUSED
 
 /* Currently we support five flavours of bitsets:
    BITSET_ARRAY:  Array of bits (fixed size, fast for dense bitsets).
diff --git a/lib/c-stack.c b/lib/c-stack.c
index 50a0380c2..4050d08e1 100644
--- a/lib/c-stack.c
+++ b/lib/c-stack.c
@@ -35,12 +35,6 @@
 
 #include <config.h>
 
-#ifndef __attribute__
-# if __GNUC__ < 3
-#  define __attribute__(x)
-# endif
-#endif
-
 #include "gettext.h"
 #define _(msgid) gettext (msgid)
 
diff --git a/lib/dfa.c b/lib/dfa.c
index 9939d228a..dee7be861 100644
--- a/lib/dfa.c
+++ b/lib/dfa.c
@@ -62,7 +62,9 @@ isasciidigit (char c)
 #include "localeinfo.h"
 
 #ifndef FALLTHROUGH
-# if __GNUC__ < 7
+# if 201710L < __STDC_VERSION__
+#  define FALLTHROUGH [[__fallthrough__]]
+# elif __GNUC__ < 7
 #  define FALLTHROUGH ((void) 0)
 # else
 #  define FALLTHROUGH __attribute__ ((__fallthrough__))
diff --git a/lib/di-set.h b/lib/di-set.h
index abc3161fe..bec5b3f9e 100644
--- a/lib/di-set.h
+++ b/lib/di-set.h
@@ -3,17 +3,10 @@
 
 # include <sys/types.h>
 
-# undef _GL_ATTRIBUTE_NONNULL
-# if __GNUC__ == 3 && __GNUC_MINOR__ >= 3 || 3 < __GNUC__
-#  define _GL_ATTRIBUTE_NONNULL(m) __attribute__ ((__nonnull__ (m)))
-# else
-#  define _GL_ATTRIBUTE_NONNULL(m)
-# endif
-
 struct di_set *di_set_alloc (void);
-int di_set_insert (struct di_set *, dev_t, ino_t) _GL_ATTRIBUTE_NONNULL (1);
-void di_set_free (struct di_set *) _GL_ATTRIBUTE_NONNULL (1);
+int di_set_insert (struct di_set *, dev_t, ino_t) _GL_ATTRIBUTE_NONNULL ((1));
+void di_set_free (struct di_set *) _GL_ATTRIBUTE_NONNULL ((1));
 int di_set_lookup (struct di_set *dis, dev_t dev, ino_t ino)
-  _GL_ATTRIBUTE_NONNULL (1);
+  _GL_ATTRIBUTE_NONNULL ((1));
 
 #endif
diff --git a/lib/fnmatch.c b/lib/fnmatch.c
index 79c1a3b2e..224512d8c 100644
--- a/lib/fnmatch.c
+++ b/lib/fnmatch.c
@@ -63,16 +63,9 @@ extern int fnmatch (const char *pattern, const char *string, int flags);
 # define SIZE_MAX ((size_t) -1)
 #endif
 
+#include "attribute.h"
 #include "flexmember.h"
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
-
 /* We often have to test for FNM_FILE_NAME and FNM_PERIOD being both set.  */
 #define NO_LEADING_PERIOD(flags) \
   ((flags & (FNM_FILE_NAME | FNM_PERIOD)) == (FNM_FILE_NAME | FNM_PERIOD))
diff --git a/lib/freopen-safer.c b/lib/freopen-safer.c
index adaa978f1..b69fd1a75 100644
--- a/lib/freopen-safer.c
+++ b/lib/freopen-safer.c
@@ -21,19 +21,13 @@
 
 #include "stdio-safer.h"
 
+#include "attribute.h"
+
 #include <errno.h>
 #include <fcntl.h>
 #include <stdbool.h>
 #include <unistd.h>
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
-
 /* Guarantee that FD is open; all smaller FDs must already be open.
    Return true if successful.  */
 static bool
diff --git a/lib/fts.c b/lib/fts.c
index bf62dfa92..3b2f693b4 100644
--- a/lib/fts.c
+++ b/lib/fts.c
@@ -70,6 +70,7 @@ static char sccsid[] = "@(#)fts.c       8.6 (Berkeley) 8/14/94";
 #include <unistd.h>
 
 #if ! _LIBC
+# include "attribute.h"
 # include "fcntl--.h"
 # include "flexmember.h"
 # include "openat.h"
diff --git a/lib/fts_.h b/lib/fts_.h
index 15c248cba..e7a9ead77 100644
--- a/lib/fts_.h
+++ b/lib/fts_.h
@@ -249,30 +249,13 @@ typedef struct _ftsent {
         char fts_name[__FLEXIBLE_ARRAY_MEMBER]; /* file name */
 } FTSENT;
 
-#ifndef __GNUC_PREREQ
-# if defined __GNUC__ && defined __GNUC_MINOR__
-#  define __GNUC_PREREQ(maj, min) \
-         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
-# else
-#  define __GNUC_PREREQ(maj, min) 0
-# endif
-#endif
-
-#if __GNUC_PREREQ (3,4)
-# undef __attribute_warn_unused_result__
-# define __attribute_warn_unused_result__ \
-   __attribute__ ((__warn_unused_result__))
-#else
-# define __attribute_warn_unused_result__ /* empty */
-#endif
-
 __BEGIN_DECLS
-FTSENT  *fts_children (FTS *, int) __THROW __attribute_warn_unused_result__;
-int      fts_close (FTS *) __THROW __attribute_warn_unused_result__;
+FTSENT  *fts_children (FTS *, int) __THROW _GL_ATTRIBUTE_NODISCARD;
+int      fts_close (FTS *) __THROW _GL_ATTRIBUTE_NODISCARD;
 FTS     *fts_open (char * const *, int,
                    int (*)(const FTSENT **, const FTSENT **))
-  __THROW __attribute_warn_unused_result__;
-FTSENT  *fts_read (FTS *) __THROW __attribute_warn_unused_result__;
+  __THROW _GL_ATTRIBUTE_NODISCARD;
+FTSENT  *fts_read (FTS *) __THROW _GL_ATTRIBUTE_NODISCARD;
 int      fts_set (FTS *, FTSENT *, int) __THROW;
 __END_DECLS
 
diff --git a/lib/gl_list.h b/lib/gl_list.h
index ea5018d34..7f164fac6 100644
--- a/lib/gl_list.h
+++ b/lib/gl_list.h
@@ -193,10 +193,7 @@ extern void gl_list_node_set_value (gl_list_t list, gl_list_node_t node,
 /* Likewise.  Returns 0 upon success, -1 upon out-of-memory.  */
 extern int gl_list_node_nx_set_value (gl_list_t list, gl_list_node_t node,
                                       const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Returns the node immediately after the given node in the list, or NULL
    if the given node is the last (rightmost) one in the list.  */
@@ -219,10 +216,7 @@ extern gl_list_node_t gl_list_set_at (gl_list_t list, size_t position,
 /* Likewise.  Returns NULL upon out-of-memory.  */
 extern gl_list_node_t gl_list_nx_set_at (gl_list_t list, size_t position,
                                          const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Searches whether an element is already in the list.
    Returns its node if found, or NULL if not present in the list.  */
@@ -265,10 +259,7 @@ extern size_t gl_list_indexof_from_to (gl_list_t list,
 extern gl_list_node_t gl_list_add_first (gl_list_t list, const void *elt);
 /* Likewise.  Returns NULL upon out-of-memory.  */
 extern gl_list_node_t gl_list_nx_add_first (gl_list_t list, const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Adds an element as the last element of the list.
    Returns its node.  */
@@ -276,10 +267,7 @@ extern gl_list_node_t gl_list_nx_add_first (gl_list_t list, const void *elt)
 extern gl_list_node_t gl_list_add_last (gl_list_t list, const void *elt);
 /* Likewise.  Returns NULL upon out-of-memory.  */
 extern gl_list_node_t gl_list_nx_add_last (gl_list_t list, const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Adds an element before a given element node of the list.
    Returns its node.  */
@@ -290,10 +278,7 @@ extern gl_list_node_t gl_list_add_before (gl_list_t list, gl_list_node_t node,
 extern gl_list_node_t gl_list_nx_add_before (gl_list_t list,
                                              gl_list_node_t node,
                                              const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Adds an element after a given element node of the list.
    Returns its node.  */
@@ -303,10 +288,7 @@ extern gl_list_node_t gl_list_add_after (gl_list_t list, gl_list_node_t node,
 /* Likewise.  Returns NULL upon out-of-memory.  */
 extern gl_list_node_t gl_list_nx_add_after (gl_list_t list, gl_list_node_t node,
                                             const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Adds an element at a given position in the list.
    POSITION must be >= 0 and <= gl_list_size (list).  */
@@ -316,10 +298,7 @@ extern gl_list_node_t gl_list_add_at (gl_list_t list, size_t position,
 /* Likewise.  Returns NULL upon out-of-memory.  */
 extern gl_list_node_t gl_list_nx_add_at (gl_list_t list, size_t position,
                                          const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Removes an element from the list.
    Returns true.  */
@@ -463,10 +442,7 @@ extern gl_list_node_t gl_sortedlist_add (gl_list_t list,
 extern gl_list_node_t gl_sortedlist_nx_add (gl_list_t list,
                                             gl_listelement_compar_fn compar,
                                             const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Searches and removes an element from the list.
    The list is assumed to be sorted with COMPAR.
@@ -605,10 +581,7 @@ gl_list_node_value (gl_list_t list, gl_list_node_t node)
          ->node_value (list, node);
 }
 
-GL_LIST_INLINE int
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD int
 gl_list_node_nx_set_value (gl_list_t list, gl_list_node_t node,
                            const void *elt)
 {
@@ -637,10 +610,7 @@ gl_list_get_at (gl_list_t list, size_t position)
          ->get_at (list, position);
 }
 
-GL_LIST_INLINE gl_list_node_t
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD gl_list_node_t
 gl_list_nx_set_at (gl_list_t list, size_t position, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
@@ -695,50 +665,35 @@ gl_list_indexof_from_to (gl_list_t list, size_t start_index, size_t end_index,
          ->indexof_from_to (list, start_index, end_index, elt);
 }
 
-GL_LIST_INLINE gl_list_node_t
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD gl_list_node_t
 gl_list_nx_add_first (gl_list_t list, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
          ->nx_add_first (list, elt);
 }
 
-GL_LIST_INLINE gl_list_node_t
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD gl_list_node_t
 gl_list_nx_add_last (gl_list_t list, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
          ->nx_add_last (list, elt);
 }
 
-GL_LIST_INLINE gl_list_node_t
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD gl_list_node_t
 gl_list_nx_add_before (gl_list_t list, gl_list_node_t node, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
          ->nx_add_before (list, node, elt);
 }
 
-GL_LIST_INLINE gl_list_node_t
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD gl_list_node_t
 gl_list_nx_add_after (gl_list_t list, gl_list_node_t node, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
          ->nx_add_after (list, node, elt);
 }
 
-GL_LIST_INLINE gl_list_node_t
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD gl_list_node_t
 gl_list_nx_add_at (gl_list_t list, size_t position, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
@@ -843,10 +798,7 @@ gl_sortedlist_indexof_from_to (gl_list_t list, gl_listelement_compar_fn compar,
                                        elt);
 }
 
-GL_LIST_INLINE gl_list_node_t
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_LIST_INLINE _GL_ATTRIBUTE_NODISCARD gl_list_node_t
 gl_sortedlist_nx_add (gl_list_t list, gl_listelement_compar_fn compar, const void *elt)
 {
   return ((const struct gl_list_impl_base *) list)->vtable
diff --git a/lib/gl_map.h b/lib/gl_map.h
index 8a203b627..977457ce8 100644
--- a/lib/gl_map.h
+++ b/lib/gl_map.h
@@ -146,10 +146,7 @@ extern bool gl_map_search (gl_map_t map, const void *key, const void **valuep);
 extern bool gl_map_put (gl_map_t map, const void *key, const void *value);
 /* Likewise.  Returns -1 upon out-of-memory.  */
 extern int gl_map_nx_put (gl_map_t map, const void *key, const void *value)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Adds a pair to a map and retrieves the previous value.
    Returns true if a pair with the given key was not already in the map and so
@@ -162,10 +159,7 @@ extern bool gl_map_getput (gl_map_t map, const void *key, const void *value,
 /* Likewise.  Returns -1 upon out-of-memory.  */
 extern int gl_map_nx_getput (gl_map_t map, const void *key, const void *value,
                              const void **oldvaluep)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Removes a pair from a map.
    Returns true if the key was found and its pair removed.
@@ -286,10 +280,7 @@ gl_map_search (gl_map_t map, const void *key, const void **valuep)
          ->search (map, key, valuep);
 }
 
-GL_MAP_INLINE int
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_MAP_INLINE _GL_ATTRIBUTE_NODISCARD int
 gl_map_nx_getput (gl_map_t map, const void *key, const void *value,
                    const void **oldvaluep)
 {
@@ -340,10 +331,7 @@ gl_map_get (gl_map_t map, const void *key)
   return value;
 }
 
-GL_MAP_INLINE int
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_MAP_INLINE _GL_ATTRIBUTE_NODISCARD int
 gl_map_nx_put (gl_map_t map, const void *key, const void *value)
 {
   const void *oldvalue;
diff --git a/lib/gl_omap.h b/lib/gl_omap.h
index c534db582..e789ba3f0 100644
--- a/lib/gl_omap.h
+++ b/lib/gl_omap.h
@@ -156,10 +156,7 @@ extern bool gl_omap_search_atleast (gl_omap_t map,
 extern bool gl_omap_put (gl_omap_t map, const void *key, const void *value);
 /* Likewise.  Returns -1 upon out-of-memory.  */
 extern int gl_omap_nx_put (gl_omap_t map, const void *key, const void *value)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Adds a pair to an ordered map and retrieves the previous value.
    Returns true if a pair with the given key was not already in the map and so
@@ -172,10 +169,7 @@ extern bool gl_omap_getput (gl_omap_t map, const void *key, const void *value,
 /* Likewise.  Returns -1 upon out-of-memory.  */
 extern int gl_omap_nx_getput (gl_omap_t map, const void *key, const void *value,
                               const void **oldvaluep)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Removes a pair from an ordered map.
    Returns true if the key was found and its pair removed.
@@ -304,10 +298,7 @@ gl_omap_search_atleast (gl_omap_t map,
          ->search_atleast (map, threshold_fn, threshold, keyp, valuep);
 }
 
-GL_OMAP_INLINE int
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_OMAP_INLINE _GL_ATTRIBUTE_NODISCARD int
 gl_omap_nx_getput (gl_omap_t map, const void *key, const void *value,
                    const void **oldvaluep)
 {
@@ -358,10 +349,7 @@ gl_omap_get (gl_omap_t map, const void *key)
   return value;
 }
 
-GL_OMAP_INLINE int
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_OMAP_INLINE _GL_ATTRIBUTE_NODISCARD int
 gl_omap_nx_put (gl_omap_t map, const void *key, const void *value)
 {
   const void *oldvalue;
diff --git a/lib/gl_oset.h b/lib/gl_oset.h
index d6fb408c0..672527cd3 100644
--- a/lib/gl_oset.h
+++ b/lib/gl_oset.h
@@ -134,10 +134,7 @@ extern bool gl_oset_search_atleast (gl_oset_t set,
 extern bool gl_oset_add (gl_oset_t set, const void *elt);
 /* Likewise.  Returns -1 upon out-of-memory.  */
 extern int gl_oset_nx_add (gl_oset_t set, const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Removes an element from an ordered set.
    Returns true if it was found and removed.  */
@@ -248,10 +245,7 @@ gl_oset_search_atleast (gl_oset_t set,
          ->search_atleast (set, threshold_fn, threshold, eltp);
 }
 
-GL_OSET_INLINE int
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_OSET_INLINE _GL_ATTRIBUTE_NODISCARD int
 gl_oset_nx_add (gl_oset_t set, const void *elt)
 {
   return ((const struct gl_oset_impl_base *) set)->vtable->nx_add (set, elt);
diff --git a/lib/gl_set.h b/lib/gl_set.h
index 0c1f9a3c6..3d48f7e3b 100644
--- a/lib/gl_set.h
+++ b/lib/gl_set.h
@@ -126,10 +126,7 @@ extern bool gl_set_search (gl_set_t set, const void *elt);
 extern bool gl_set_add (gl_set_t set, const void *elt);
 /* Likewise.  Returns -1 upon out-of-memory.  */
 extern int gl_set_nx_add (gl_set_t set, const void *elt)
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
-  ;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /* Removes an element from a set.
    Returns true if it was found and removed.  */
@@ -233,10 +230,7 @@ gl_set_search (gl_set_t set, const void *elt)
   return ((const struct gl_set_impl_base *) set)->vtable->search (set, elt);
 }
 
-GL_SET_INLINE int
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-  __attribute__ ((__warn_unused_result__))
-#endif
+GL_SET_INLINE _GL_ATTRIBUTE_NODISCARD int
 gl_set_nx_add (gl_set_t set, const void *elt)
 {
   return ((const struct gl_set_impl_base *) set)->vtable->nx_add (set, elt);
diff --git a/lib/hash.h b/lib/hash.h
index 2ff4266a4..ae08ce867 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -27,24 +27,6 @@
 # include <stdio.h>
 # include <stdbool.h>
 
-/* The __attribute__ feature is available in gcc versions 2.5 and later.
-   The warn_unused_result attribute appeared first in gcc-3.4.0.  */
-# if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-#  define _GL_ATTRIBUTE_WUR __attribute__ ((__warn_unused_result__))
-# else
-#  define _GL_ATTRIBUTE_WUR /* empty */
-# endif
-
-# ifndef _GL_ATTRIBUTE_DEPRECATED
-/* The __attribute__((__deprecated__)) feature
-   is available in gcc versions 3.1 and newer.  */
-#  if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 1)
-#   define _GL_ATTRIBUTE_DEPRECATED /* empty */
-#  else
-#   define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
-#  endif
-# endif
-
 typedef size_t (*Hash_hasher) (const void *, size_t);
 typedef bool (*Hash_comparator) (const void *, const void *);
 typedef void (*Hash_data_freer) (void *);
@@ -88,16 +70,16 @@ size_t hash_string (const char *, size_t) _GL_ATTRIBUTE_PURE;
 void hash_reset_tuning (Hash_tuning *);
 Hash_table *hash_initialize (size_t, const Hash_tuning *,
                              Hash_hasher, Hash_comparator,
-                             Hash_data_freer) _GL_ATTRIBUTE_WUR;
+                             Hash_data_freer) _GL_ATTRIBUTE_NODISCARD;
 Hash_table *hash_xinitialize (size_t, const Hash_tuning *,
                               Hash_hasher, Hash_comparator,
-                              Hash_data_freer) _GL_ATTRIBUTE_WUR;
+                              Hash_data_freer) _GL_ATTRIBUTE_NODISCARD;
 void hash_clear (Hash_table *);
 void hash_free (Hash_table *);
 
 /* Insertion and deletion.  */
-bool hash_rehash (Hash_table *, size_t) _GL_ATTRIBUTE_WUR;
-void *hash_insert (Hash_table *, const void *) _GL_ATTRIBUTE_WUR;
+bool hash_rehash (Hash_table *, size_t) _GL_ATTRIBUTE_NODISCARD;
+void *hash_insert (Hash_table *, const void *) _GL_ATTRIBUTE_NODISCARD;
 
 int hash_insert_if_absent (Hash_table *table, const void *entry,
                            const void **matched_ent);
diff --git a/lib/ino-map.h b/lib/ino-map.h
index b7422912f..1bdf886f4 100644
--- a/lib/ino-map.h
+++ b/lib/ino-map.h
@@ -3,17 +3,10 @@
 
 # include <sys/types.h>
 
-# undef _GL_ATTRIBUTE_NONNULL
-# if __GNUC__ == 3 && __GNUC_MINOR__ >= 3 || 3 < __GNUC__
-#  define _GL_ATTRIBUTE_NONNULL(m) __attribute__ ((__nonnull__ (m)))
-# else
-#  define _GL_ATTRIBUTE_NONNULL(m)
-# endif
-
 # define INO_MAP_INSERT_FAILURE ((size_t) -1)
 
 struct ino_map *ino_map_alloc (size_t);
-void ino_map_free (struct ino_map *) _GL_ATTRIBUTE_NONNULL (1);
-size_t ino_map_insert (struct ino_map *, ino_t) _GL_ATTRIBUTE_NONNULL (1);
+void ino_map_free (struct ino_map *) _GL_ATTRIBUTE_NONNULL ((1));
+size_t ino_map_insert (struct ino_map *, ino_t) _GL_ATTRIBUTE_NONNULL ((1));
 
 #endif
diff --git a/lib/inttostr.h b/lib/inttostr.h
index f1c20815e..39b437683 100644
--- a/lib/inttostr.h
+++ b/lib/inttostr.h
@@ -22,25 +22,8 @@
 
 #include "intprops.h"
 
-#ifndef __GNUC_PREREQ
-# if defined __GNUC__ && defined __GNUC_MINOR__
-#  define __GNUC_PREREQ(maj, min) \
-         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
-# else
-#  define __GNUC_PREREQ(maj, min) 0
-# endif
-#endif
-
-#if __GNUC_PREREQ (3,4)
-# undef __attribute_warn_unused_result__
-# define __attribute_warn_unused_result__ \
-   __attribute__ ((__warn_unused_result__))
-#else
-# define __attribute_warn_unused_result__ /* empty */
-#endif
-
-char *imaxtostr (intmax_t, char *) __attribute_warn_unused_result__;
-char *inttostr (int, char *) __attribute_warn_unused_result__;
-char *offtostr (off_t, char *) __attribute_warn_unused_result__;
-char *uinttostr (unsigned int, char *) __attribute_warn_unused_result__;
-char *umaxtostr (uintmax_t, char *) __attribute_warn_unused_result__;
+char *imaxtostr (intmax_t, char *) _GL_ATTRIBUTE_NODISCARD;
+char *inttostr (int, char *) _GL_ATTRIBUTE_NODISCARD;
+char *offtostr (off_t, char *) _GL_ATTRIBUTE_NODISCARD;
+char *uinttostr (unsigned int, char *) _GL_ATTRIBUTE_NODISCARD;
+char *umaxtostr (uintmax_t, char *) _GL_ATTRIBUTE_NODISCARD;
diff --git a/lib/mbrtoc32.c b/lib/mbrtoc32.c
index facf28bc5..dc35ba2d4 100644
--- a/lib/mbrtoc32.c
+++ b/lib/mbrtoc32.c
@@ -21,17 +21,11 @@
 /* Specification.  */
 #include <uchar.h>
 
+#include <attribute.h>
+
 #include <errno.h>
 #include <stdlib.h>
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
-
 #if GNULIB_defined_mbstate_t /* AIX, IRIX */
 /* Implement mbrtoc32() on top of mbtowc() for the non-UTF-8 locales
    and directly for the UTF-8 locales.  */
diff --git a/lib/mbrtowc.c b/lib/mbrtowc.c
index 6cb52675b..a71d39430 100644
--- a/lib/mbrtowc.c
+++ b/lib/mbrtowc.c
@@ -50,18 +50,11 @@
 
 # endif
 
+# include "attribute.h"
 # include "verify.h"
 # include "lc-charset-dispatch.h"
 # include "mbtowc-lock.h"
 
-# ifndef FALLTHROUGH
-#  if __GNUC__ < 7
-#   define FALLTHROUGH ((void) 0)
-#  else
-#   define FALLTHROUGH __attribute__ ((__fallthrough__))
-#  endif
-# endif
-
 verify (sizeof (mbstate_t) >= 4);
 static char internal_state[4];
 
diff --git a/lib/nstrftime.c b/lib/nstrftime.c
index 8c520ce61..5326de60f 100644
--- a/lib/nstrftime.c
+++ b/lib/nstrftime.c
@@ -68,16 +68,9 @@ extern char *tzname[];
 #include <string.h>
 #include <stdbool.h>
 
+#include <attribute.h>
 #include <intprops.h>
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
-
 #ifdef COMPILE_WIDE
 # include <endian.h>
 # define CHAR_T wchar_t
diff --git a/lib/quotearg.c b/lib/quotearg.c
index c78fc1670..b13574d2f 100644
--- a/lib/quotearg.c
+++ b/lib/quotearg.c
@@ -29,6 +29,7 @@
 #include "quotearg.h"
 #include "quote.h"
 
+#include "attribute.h"
 #include "minmax.h"
 #include "xalloc.h"
 #include "c-strcaseeq.h"
@@ -54,14 +55,6 @@
 
 #define INT_BITS (sizeof (int) * CHAR_BIT)
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
-
 struct quoting_options
 {
   /* Basic quoting style.  */
diff --git a/lib/safe-alloc.h b/lib/safe-alloc.h
index 3c9f20fa0..58970bd00 100644
--- a/lib/safe-alloc.h
+++ b/lib/safe-alloc.h
@@ -31,22 +31,14 @@
 # endif
 #endif
 
-# ifndef _GL_ATTRIBUTE_RETURN_CHECK
-#  if __GNUC_PREREQ (3, 4)
-#   define _GL_ATTRIBUTE_RETURN_CHECK __attribute__((__warn_unused_result__))
-#  else
-#   define _GL_ATTRIBUTE_RETURN_CHECK
-#  endif
-# endif
-
 /* Don't call these directly - use the macros below */
 int
 safe_alloc_alloc_n (void *ptrptr, size_t size, size_t count, int zeroed)
-  _GL_ATTRIBUTE_RETURN_CHECK;
+  _GL_ATTRIBUTE_NODISCARD;
 
 int
 safe_alloc_realloc_n (void *ptrptr, size_t size, size_t count)
-  _GL_ATTRIBUTE_RETURN_CHECK;
+  _GL_ATTRIBUTE_NODISCARD;
 
 /**
  * ALLOC:
diff --git a/lib/savewd.c b/lib/savewd.c
index 2b68e417b..ecc70fbcc 100644
--- a/lib/savewd.c
+++ b/lib/savewd.c
@@ -33,17 +33,10 @@
 #include <unistd.h>
 
 #include "assure.h"
+#include "attribute.h"
 #include "fcntl-safer.h"
 #include "filename.h"
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
-
 /* Save the working directory into *WD, if it hasn't been saved
    already.  Return true if a child has been forked to do the real
    work.  */
diff --git a/lib/unistr/u8-uctomb-aux.c b/lib/unistr/u8-uctomb-aux.c
index 976f8d398..0b5ec9064 100644
--- a/lib/unistr/u8-uctomb-aux.c
+++ b/lib/unistr/u8-uctomb-aux.c
@@ -20,13 +20,7 @@
 /* Specification.  */
 #include "unistr.h"
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
+#include "attribute.h"
 
 int
 u8_uctomb_aux (uint8_t *s, ucs4_t uc, int n)
diff --git a/lib/unistr/u8-uctomb.c b/lib/unistr/u8-uctomb.c
index d9980022c..7cf338963 100644
--- a/lib/unistr/u8-uctomb.c
+++ b/lib/unistr/u8-uctomb.c
@@ -25,13 +25,7 @@
 /* Specification.  */
 #include "unistr.h"
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
+#include "attribute.h"
 
 #if !HAVE_INLINE
 
diff --git a/lib/unused-parameter.h b/lib/unused-parameter.h
index dd8be7c57..baf80c03a 100644
--- a/lib/unused-parameter.h
+++ b/lib/unused-parameter.h
@@ -28,9 +28,5 @@
        _GL_UNUSED_PARAMETER int *(*param)(void)
  */
 #ifndef _GL_UNUSED_PARAMETER
-# if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
-#  define _GL_UNUSED_PARAMETER __attribute__ ((__unused__))
-# else
-#  define _GL_UNUSED_PARAMETER
-# endif
+# define _GL_UNUSED_PARAMETER _GL_ATTRIBUTE_MAYBE_UNUSED
 #endif
diff --git a/lib/vasnprintf.c b/lib/vasnprintf.c
index b3b6e7b78..0cdc6c095 100644
--- a/lib/vasnprintf.c
+++ b/lib/vasnprintf.c
@@ -94,6 +94,7 @@
 /* Checked size_t computations.  */
 #include "xsize.h"
 
+#include "attribute.h"
 #include "verify.h"
 
 #if (NEED_PRINTF_DOUBLE || NEED_PRINTF_LONG_DOUBLE) && !defined IN_LIBINTL
@@ -125,14 +126,6 @@
 # include "fpucw.h"
 #endif
 
-#ifndef FALLTHROUGH
-# if __GNUC__ < 7
-#  define FALLTHROUGH ((void) 0)
-# else
-#  define FALLTHROUGH __attribute__ ((__fallthrough__))
-# endif
-#endif
-
 /* Default parameters.  */
 #ifndef VASNPRINTF
 # if WIDE_CHAR_VERSION
diff --git a/m4/gnulib-common.m4 b/m4/gnulib-common.m4
index b4795c18a..1a817662c 100644
--- a/m4/gnulib-common.m4
+++ b/m4/gnulib-common.m4
@@ -1,4 +1,4 @@
-# gnulib-common.m4 serial 48
+# gnulib-common.m4 serial 49
 dnl Copyright (C) 2007-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -15,6 +15,15 @@ AC_DEFUN([gl_COMMON], [
   AC_REQUIRE([gl_ZZGNULIB])
 ])
 AC_DEFUN([gl_COMMON_BODY], [
+  AH_VERBATIM([_GL_GNUC_PREREQ],
+[/* True if the compiler says it groks GNU C version MAJOR.MINOR.  */
+#if defined __GNUC__ && defined __GNUC_MINOR__
+# define _GL_GNUC_PREREQ(major, minor) \
+    ((major) < __GNUC__ + ((minor) <= __GNUC_MINOR__))
+#else
+# define _GL_GNUC_PREREQ(major, minor) 0
+#endif
+])
   AH_VERBATIM([_Noreturn],
 [/* The _Noreturn keyword of C11.  */
 #ifndef _Noreturn
@@ -31,12 +40,12 @@ AC_DEFUN([gl_COMMON_BODY], [
 #  define _Noreturn [[noreturn]]
 # elif ((!defined __cplusplus || defined __clang__) \
         && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0)  \
-            || 4 < __GNUC__ + (7 <= __GNUC_MINOR__) \
+            || _GL_GNUC_PREREQ (4, 7) \
             || (defined __apple_build_version__ \
                 ? 6000000 <= __apple_build_version__ \
                 : 3 < __clang_major__ + (5 <= __clang_minor__))))
    /* _Noreturn works as-is.  */
-# elif 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || 0x5110 <= __SUNPRO_C
+# elif _GL_GNUC_PREREQ (2, 8) || 0x5110 <= __SUNPRO_C
 #  define _Noreturn __attribute__ ((__noreturn__))
 # elif 1200 <= (defined _MSC_VER ? _MSC_VER : 0)
 #  define _Noreturn __declspec (noreturn)
@@ -55,48 +64,200 @@ AC_DEFUN([gl_COMMON_BODY], [
 #if defined __APPLE__ && defined __MACH__ && __APPLE_CC__ >= 5465 && !defined __cplusplus && __STDC_VERSION__ >= 199901L && !defined __GNUC_STDC_INLINE__
 # define __GNUC_STDC_INLINE__ 1
 #endif])
-  AH_VERBATIM([unused_parameter],
-[/* Define as a marker that can be attached to declarations that might not
-    be used.  This helps to reduce warnings, such as from
-    GCC -Wunused-parameter.  */
-#if __GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
-# define _GL_UNUSED __attribute__ ((__unused__))
+  AH_VERBATIM([attribute],
+[/* Attributes.  */
+#ifdef __has_attribute
+# define _GL_HAS_ATTRIBUTE(attr) __has_attribute (__##attr##__)
 #else
-# define _GL_UNUSED
+# define _GL_HAS_ATTRIBUTE(attr) _GL_ATTR_##attr
+# define _GL_ATTR_alloc_size _GL_GNUC_PREREQ (4, 3)
+# define _GL_ATTR_always_inline _GL_GNUC_PREREQ (3, 2)
+# define _GL_ATTR_artificial _GL_GNUC_PREREQ (4, 3)
+# define _GL_ATTR_cold _GL_GNUC_PREREQ (4, 3)
+# define _GL_ATTR_const _GL_GNUC_PREREQ (2, 95)
+# define _GL_ATTR_deprecated _GL_GNUC_PREREQ (3, 1)
+# define _GL_ATTR_error _GL_GNUC_PREREQ (4, 3)
+# define _GL_ATTR_externally_visible _GL_GNUC_PREREQ (4, 1)
+# define _GL_ATTR_fallthrough _GL_GNUC_PREREQ (7, 0)
+# define _GL_ATTR_format _GL_GNUC_PREREQ (2, 7)
+# define _GL_ATTR_leaf _GL_GNUC_PREREQ (4, 6)
+# ifdef _ICC
+#  define _GL_ATTR_may_alias 0
+# else
+#  define _GL_ATTR_may_alias _GL_GNUC_PREREQ (3, 3)
+# endif
+# define _GL_ATTR_malloc _GL_GNUC_PREREQ (3, 0)
+# define _GL_ATTR_noinline _GL_GNUC_PREREQ (3, 1)
+# define _GL_ATTR_nonnull _GL_GNUC_PREREQ (3, 3)
+# define _GL_ATTR_nonstring _GL_GNUC_PREREQ (8, 0)
+# define _GL_ATTR_nothrow _GL_GNUC_PREREQ (3, 3)
+# define _GL_ATTR_packed _GL_GNUC_PREREQ (2, 7)
+# define _GL_ATTR_pure _GL_GNUC_PREREQ (2, 96)
+# define _GL_ATTR_returns_nonnull _GL_GNUC_PREREQ (4, 9)
+# define _GL_ATTR_sentinel _GL_GNUC_PREREQ (4, 0)
+# define _GL_ATTR_unused _GL_GNUC_PREREQ (2, 7)
+# define _GL_ATTR_warn_unused_result_GL_GNUC_PREREQ (3, 4)
 #endif
-/* The name _UNUSED_PARAMETER_ is an earlier spelling, although the name
-   is a misnomer outside of parameter lists.  */
-#define _UNUSED_PARAMETER_ _GL_UNUSED
-
-/* gcc supports the "unused" attribute on possibly unused labels, and
-   g++ has since version 4.5.  Note to support C++ as well as C,
-   _GL_UNUSED_LABEL should be used with a trailing ;  */
-#if !defined __cplusplus || __GNUC__ > 4 \
-    || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
-# define _GL_UNUSED_LABEL _GL_UNUSED
+
+]dnl There is no _GL_ATTRIBUTE_ALIGNED; use stdalign's _Alignas instead.
+[
+#if _GL_HAS_ATTRIBUTE (alloc_size)
+# define _GL_ATTRIBUTE_ALLOC_SIZE(args) __attribute__ ((__alloc_size__ args))
 #else
-# define _GL_UNUSED_LABEL
+# define _GL_ATTRIBUTE_ALLOC_SIZE(args)
 #endif
 
-/* The __pure__ attribute was added in gcc 2.96.  */
-#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96)
-# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
+#if _GL_HAS_ATTRIBUTE (always_inline)
+# define _GL_ATTRIBUTE_ALWAYS_INLINE __attribute__ ((__always_inline__))
 #else
-# define _GL_ATTRIBUTE_PURE /* empty */
+# define _GL_ATTRIBUTE_ALWAYS_INLINE
 #endif
 
-/* The __const__ attribute was added in gcc 2.95.  */
-#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
+#if _GL_HAS_ATTRIBUTE (artificial)
+# define _GL_ATTRIBUTE_ARTIFICIAL __attribute__ ((__artificial__))
+#else
+# define _GL_ATTRIBUTE_ARTIFICIAL
+#endif
+
+/* Avoid __attribute__ ((cold)) on MinGW; see thread starting at
+   <https://lists.gnu.org/r/emacs-devel/2019-04/msg01152.html>. */
+#if _GL_HAS_ATTRIBUTE (cold) && !defined __MINGW32__
+# define _GL_ATTRIBUTE_COLD __attribute__ ((cold))
+#else
+# define _GL_ATTRIBUTE_COLD
+#endif
+
+#if _GL_HAS_ATTRIBUTE (const)
 # define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
 #else
-# define _GL_ATTRIBUTE_CONST /* empty */
+# define _GL_ATTRIBUTE_CONST
+#endif
+
+#if 201710L < __STDC_VERSION__
+# define _GL_ATTRIBUTE_DEPRECATED [[__deprecated__]]
+#elif _GL_HAS_ATTRIBUTE (deprecated)
+# define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
+#else
+# define _GL_ATTRIBUTE_DEPRECATED
+#endif
+
+#if _GL_HAS_ATTRIBUTE (error)
+# define _GL_ATTRIBUTE_ERROR(msg) __attribute__((__error__ (msg)))
+# define _GL_ATTRIBUTE_WARNING(msg) __attribute__((__warning__ (msg)))
+#else
+# define _GL_ATTRIBUTE_ERROR(msg)
+# define _GL_ATTRIBUTE_WARNING(msg)
+#endif
+
+#if _GL_HAS_ATTRIBUTE (externally_visible)
+# define _GL_ATTRIBUTE_EXTERNALLY_VISIBLE __attribute__ ((externally_visible))
+#else
+# define _GL_ATTRIBUTE_EXTERNALLY_VISIBLE
+#endif
+
+/* FALLTHROUGH is special, because it always expands to something.  */
+#if 201710L < __STDC_VERSION__
+# define _GL_ATTRIBUTE_FALLTHROUGH [[__fallthrough__]]
+#elif _GL_HAS_ATTRIBUTE (fallthrough)
+# define _GL_ATTRIBUTE_FALLTHROUGH __attribute__ ((__fallthrough__))
+#else
+# define _GL_ATTRIBUTE_FALLTHROUGH ((void) 0)
+#endif
+
+#if _GL_HAS_ATTRIBUTE (format)
+# define _GL_ATTRIBUTE_FORMAT(spec) __attribute__ ((__format__ spec))
+#else
+# define _GL_ATTRIBUTE_FORMAT(spec)
+#endif
+
+#if _GL_HAS_ATTRIBUTE (leaf)
+# define _GL_ATTRIBUTE_LEAF __attribute__ ((__leaf__))
+#else
+# define _GL_ATTRIBUTE_LEAF
+#endif
+
+#if _GL_HAS_ATTRIBUTE (may_alias)
+# define _GL_ATTRIBUTE_MAY_ALIAS __attribute__ ((__may_alias__))
+#else
+# define _GL_ATTRIBUTE_MAY_ALIAS
 #endif
 
-/* The __malloc__ attribute was added in gcc 3.  */
-#if 3 <= __GNUC__
+#if 201710L < __STDC_VERSION__
+# define _GL_ATTRIBUTE_MAYBE_UNUSED [[__maybe_unused__]]
+#elif _GL_HAS_ATTRIBUTE (unused)
+# define _GL_ATTRIBUTE_MAYBE_UNUSED __attribute__ ((__unused__))
+#else
+# define _GL_ATTRIBUTE_MAYBE_UNUSED
+#endif
+/* Earlier spellings of this macro.  */
+#define _GL_UNUSED _GL_ATTRIBUTE_MAYBE_UNUSED
+#define _UNUSED_PARAMETER_ _GL_ATTRIBUTE_MAYBE_UNUSED
+
+#if _GL_HAS_ATTRIBUTE (malloc)
 # define _GL_ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
 #else
-# define _GL_ATTRIBUTE_MALLOC /* empty */
+# define _GL_ATTRIBUTE_MALLOC
+#endif
+
+#if 201710L < __STDC_VERSION__
+# define _GL_ATTRIBUTE_NODISCARD [[__nodiscard__]]
+#elif _GL_HAS_ATTRIBUTE (warn_unused_result)
+# define _GL_ATTRIBUTE_NODISCARD __attribute__ ((__warn_unused_result__))
+#else
+# define _GL_ATTRIBUTE_NODISCARD
+#endif
+
+#if _GL_HAS_ATTRIBUTE (noinline)
+# define _GL_ATTRIBUTE_NOINLINE __attribute__ ((__noinline__))
+#else
+# define _GL_ATTRIBUTE_NOINLINE
+#endif
+
+#if _GL_HAS_ATTRIBUTE (nonnull)
+# define _GL_ATTRIBUTE_NONNULL(args) __attribute__ ((__nonnull__ args))
+#else
+# define _GL_ATTRIBUTE_NONNULL(args)
+#endif
+
+#if _GL_HAS_ATTRIBUTE (nonstring)
+# define _GL_ATTRIBUTE_NONSTRING __attribute__ ((__nonstring__))
+#else
+# define _GL_ATTRIBUTE_NONSTRING
+#endif
+
+/* There is no _GL_ATTRIBUTE_NORETURN; use _Noreturn instead.  */
+
+#if _GL_HAS_ATTRIBUTE (nothrow) && !defined __cplusplus
+# define _GL_ATTRIBUTE_NOTHROW __attribute__ ((__nothrow__))
+#else
+# define _GL_ATTRIBUTE_NOTHROW
+#endif
+
+#if _GL_HAS_ATTRIBUTE (packed)
+# define _GL_ATTRIBUTE_PACKED __attribute__ ((__packed__))
+#else
+# define _GL_ATTRIBUTE_PACKED
+#endif
+
+#if _GL_HAS_ATTRIBUTE (pure)
+# define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
+#else
+# define _GL_ATTRIBUTE_PURE
+#endif
+
+#if _GL_HAS_ATTRIBUTE (sentinel)
+# define _GL_ATTRIBUTE_SENTINEL(pos) __attribute__ ((__sentinel__ pos))
+#else
+# define _GL_ATTRIBUTE_SENTINEL(pos)
+#endif
+
+]dnl There is no _GL_ATTRIBUTE_VISIBILITY; see m4/visibility.m4 instead.
+[
+/* To support C++ as well as C, use _GL_UNUSED_LABEL with trailing ';'.  */
+#if !defined __cplusplus || _GL_GNUC_PREREQ (4, 5)
+# define _GL_UNUSED_LABEL _GL_ATTRIBUTE_MAYBE_UNUSED
+#else
+# define _GL_UNUSED_LABEL
 #endif
 ])
   AH_VERBATIM([async_safe],
diff --git a/modules/attribute b/modules/attribute
new file mode 100644
index 000000000..fcb0442c7
--- /dev/null
+++ b/modules/attribute
@@ -0,0 +1,19 @@
+Description:
+C/C++ attributes
+
+Files:
+lib/attribute.h
+
+Depends-on:
+
+configure.ac:
+
+Makefile.am:
+
+Include:
+
+License:
+LGPLv2+
+
+Maintainer:
+all
diff --git a/modules/backup-rename b/modules/backup-rename
index 0d6c34bd5..1e29b73be 100644
--- a/modules/backup-rename
+++ b/modules/backup-rename
@@ -10,6 +10,7 @@ m4/backupfile.m4
 
 Depends-on:
 argmatch
+attribute
 closedir
 d-ino
 dirent-safer
diff --git a/modules/backupfile b/modules/backupfile
index 7916d6adc..dc46d7687 100644
--- a/modules/backupfile
+++ b/modules/backupfile
@@ -10,6 +10,7 @@ m4/backupfile.m4
 
 Depends-on:
 argmatch
+attribute
 closedir
 d-ino
 dirent-safer
diff --git a/modules/c-vasnprintf b/modules/c-vasnprintf
index 391d9647f..5fe1fa7d6 100644
--- a/modules/c-vasnprintf
+++ b/modules/c-vasnprintf
@@ -22,6 +22,7 @@ m4/math_h.m4
 m4/exponentd.m4
 
 Depends-on:
+attribute
 isnand-nolibm
 isnanl-nolibm
 frexpl-nolibm
diff --git a/modules/fnmatch b/modules/fnmatch
index 50a2c7183..c7977b4fb 100644
--- a/modules/fnmatch
+++ b/modules/fnmatch
@@ -10,6 +10,7 @@ m4/fnmatch.m4
 Depends-on:
 fnmatch-h
 alloca          [test $HAVE_FNMATCH = 0 || test $REPLACE_FNMATCH = 1]
+attribute       [test $HAVE_FNMATCH = 0 || test $REPLACE_FNMATCH = 1]
 builtin-expect  [test $HAVE_FNMATCH = 0 || test $REPLACE_FNMATCH = 1]
 flexmember      [test $HAVE_FNMATCH = 0 || test $REPLACE_FNMATCH = 1]
 stdbool         [test $HAVE_FNMATCH = 0 || test $REPLACE_FNMATCH = 1]
diff --git a/modules/freopen-safer b/modules/freopen-safer
index bfeb0ce88..8b1e8655a 100644
--- a/modules/freopen-safer
+++ b/modules/freopen-safer
@@ -7,6 +7,7 @@ lib/stdio-safer.h
 lib/freopen-safer.c
 
 Depends-on:
+attribute
 dup2
 freopen
 open
diff --git a/modules/fts b/modules/fts
index 3e09bcc91..480700b1c 100644
--- a/modules/fts
+++ b/modules/fts
@@ -8,6 +8,7 @@ lib/fts-cycle.c
 m4/fts.m4
 
 Depends-on:
+attribute
 closedir
 cycle-check
 d-ino
diff --git a/modules/mbrtoc32 b/modules/mbrtoc32
index cf418464e..e99c0f0a0 100644
--- a/modules/mbrtoc32
+++ b/modules/mbrtoc32
@@ -18,6 +18,7 @@ m4/visibility.m4
 
 Depends-on:
 uchar
+attribute       [test $HAVE_MBRTOC32 = 0 || test $REPLACE_MBRTOC32 = 1]
 hard-locale     [{ test $HAVE_MBRTOC32 = 0 || test $REPLACE_MBRTOC32 = 1; } && test $REPLACE_MBSTATE_T = 0]
 mbrtowc         [{ test $HAVE_MBRTOC32 = 0 || test $REPLACE_MBRTOC32 = 1; } && test $REPLACE_MBSTATE_T = 0]
 localcharset    [test $HAVE_MBRTOC32 = 0 || test $REPLACE_MBRTOC32 = 1]
diff --git a/modules/mbrtowc b/modules/mbrtowc
index 294050f94..0b6478e90 100644
--- a/modules/mbrtowc
+++ b/modules/mbrtowc
@@ -22,6 +22,7 @@ m4/visibility.m4
 Depends-on:
 wchar
 extensions
+attribute       [test $HAVE_MBRTOWC = 0 || test $REPLACE_MBRTOWC = 1]
 stdint          [test $HAVE_MBRTOWC = 0 || test $REPLACE_MBRTOWC = 1]
 hard-locale     [{ test $HAVE_MBRTOWC = 0 || test $REPLACE_MBRTOWC = 1; } && test $REPLACE_MBSTATE_T = 0]
 mbsinit         [{ test $HAVE_MBRTOWC = 0 || test $REPLACE_MBRTOWC = 1; } && test $REPLACE_MBSTATE_T = 0]
diff --git a/modules/nstrftime b/modules/nstrftime
index a1ce1b33f..7ff82896b 100644
--- a/modules/nstrftime
+++ b/modules/nstrftime
@@ -8,6 +8,7 @@ m4/tm_gmtoff.m4
 m4/nstrftime.m4
 
 Depends-on:
+attribute
 extensions
 intprops
 stdbool
diff --git a/modules/quotearg b/modules/quotearg
index 9d9276ed1..6f5356dcc 100644
--- a/modules/quotearg
+++ b/modules/quotearg
@@ -10,6 +10,7 @@ m4/mbrtowc.m4
 m4/quotearg.m4
 
 Depends-on:
+attribute
 c-strcaseeq
 extensions
 gettext-h
diff --git a/modules/savewd b/modules/savewd
index 935540cbd..198596ef6 100644
--- a/modules/savewd
+++ b/modules/savewd
@@ -8,6 +8,7 @@ m4/savewd.m4
 
 Depends-on:
 assure
+attribute
 chdir
 errno
 extern-inline
diff --git a/modules/unistdio/u16-u16-vasnprintf b/modules/unistdio/u16-u16-vasnprintf
index 6997f372f..cae63721b 100644
--- a/modules/unistdio/u16-u16-vasnprintf
+++ b/modules/unistdio/u16-u16-vasnprintf
@@ -30,6 +30,7 @@ unistr/u16-strlen
 unistr/u16-strmblen
 unistr/u32-strlen
 unistr/u32-strmblen
+attribute
 isnand-nolibm
 isnanl-nolibm
 frexpl-nolibm
diff --git a/modules/unistdio/u16-vasnprintf b/modules/unistdio/u16-vasnprintf
index 29c82a6b9..940ff2eae 100644
--- a/modules/unistdio/u16-vasnprintf
+++ b/modules/unistdio/u16-vasnprintf
@@ -30,6 +30,7 @@ unistr/u16-strlen
 unistr/u16-strmblen
 unistr/u32-strlen
 unistr/u32-strmblen
+attribute
 isnand-nolibm
 isnanl-nolibm
 frexpl-nolibm
diff --git a/modules/unistdio/u32-u32-vasnprintf b/modules/unistdio/u32-u32-vasnprintf
index 58f657997..358cb73e6 100644
--- a/modules/unistdio/u32-u32-vasnprintf
+++ b/modules/unistdio/u32-u32-vasnprintf
@@ -30,6 +30,7 @@ unistr/u16-strlen
 unistr/u16-strmblen
 unistr/u32-strlen
 unistr/u32-strmblen
+attribute
 isnand-nolibm
 isnanl-nolibm
 frexpl-nolibm
diff --git a/modules/unistdio/u32-vasnprintf b/modules/unistdio/u32-vasnprintf
index be0c3cd11..2167c4781 100644
--- a/modules/unistdio/u32-vasnprintf
+++ b/modules/unistdio/u32-vasnprintf
@@ -30,6 +30,7 @@ unistr/u16-strlen
 unistr/u16-strmblen
 unistr/u32-strlen
 unistr/u32-strmblen
+attribute
 isnand-nolibm
 isnanl-nolibm
 frexpl-nolibm
diff --git a/modules/unistdio/u8-u8-vasnprintf b/modules/unistdio/u8-u8-vasnprintf
index 57ed3fe76..6ac98b63b 100644
--- a/modules/unistdio/u8-u8-vasnprintf
+++ b/modules/unistdio/u8-u8-vasnprintf
@@ -30,6 +30,7 @@ unistr/u16-strlen
 unistr/u16-strmblen
 unistr/u32-strlen
 unistr/u32-strmblen
+attribute
 isnand-nolibm
 isnanl-nolibm
 frexpl-nolibm
diff --git a/modules/unistdio/u8-vasnprintf b/modules/unistdio/u8-vasnprintf
index 884179032..7a6654003 100644
--- a/modules/unistdio/u8-vasnprintf
+++ b/modules/unistdio/u8-vasnprintf
@@ -30,6 +30,7 @@ unistr/u16-strlen
 unistr/u16-strmblen
 unistr/u32-strlen
 unistr/u32-strmblen
+attribute
 isnand-nolibm
 isnanl-nolibm
 frexpl-nolibm
diff --git a/modules/unistdio/ulc-vasnprintf b/modules/unistdio/ulc-vasnprintf
index 750602f86..9c8f48f40 100644
--- a/modules/unistdio/ulc-vasnprintf
+++ b/modules/unistdio/ulc-vasnprintf
@@ -27,6 +27,7 @@ unistr/u16-strlen
 unistr/u16-strmblen
 unistr/u32-strlen
 unistr/u32-strmblen
+attribute
 mbsnlen
 isnand-nolibm
 isnanl-nolibm
diff --git a/modules/unistr/u8-uctomb b/modules/unistr/u8-uctomb
index c32b2d6b0..7cc94e0da 100644
--- a/modules/unistr/u8-uctomb
+++ b/modules/unistr/u8-uctomb
@@ -7,6 +7,7 @@ lib/unistr/u8-uctomb-aux.c
 
 Depends-on:
 unistr/base
+attribute
 
 configure.ac:
 gl_MODULE_INDICATOR([unistr/u8-uctomb])
diff --git a/modules/vasnprintf b/modules/vasnprintf
index de8537acb..893ce974b 100644
--- a/modules/vasnprintf
+++ b/modules/vasnprintf
@@ -22,6 +22,7 @@ m4/exponentd.m4
 
 Depends-on:
 alloca-opt
+attribute
 float
 stdint
 xsize
-- 
2.17.1

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