Update gnulib

This updates gnulib to a relatively recent commit.  Most of this was
done by the gnulib import script; the only change I made was to
update-gnulib.sh.

Tested on x86-64 Fedora 34.  I also did a mingw cross build.

1 files changed, 368 insertions, 132 deletions

diff --git a/gnulib/config.in b/gnulib/config.in
index dd960bf..f9cce7b 100644
--- a/gnulib/config.in
+++ b/gnulib/config.in
@@ -72,7 +72,11 @@
 #undef FUNC_MKDIR_DOT_BUG
 
 /* Define to 1 if realpath() can malloc memory, always gives an absolute path,
-   and handles trailing slash correctly. */
+   and handles a trailing slash correctly. */
+#undef FUNC_REALPATH_NEARLY_WORKS
+
+/* Define to 1 if realpath() can malloc memory, always gives an absolute path,
+   and handles leading slashes and a trailing slash correctly. */
 #undef FUNC_REALPATH_WORKS
 
 /* Define this to 'void' or 'struct timezone' to match the system's
@@ -195,9 +199,27 @@
 /* Define to 1 when the gnulib module fdopendir should be tested. */
 #undef GNULIB_TEST_FDOPENDIR
 
+/* Define to 1 when the gnulib module fgetc should be tested. */
+#undef GNULIB_TEST_FGETC
+
+/* Define to 1 when the gnulib module fgets should be tested. */
+#undef GNULIB_TEST_FGETS
+
 /* Define to 1 when the gnulib module fnmatch should be tested. */
 #undef GNULIB_TEST_FNMATCH
 
+/* Define to 1 when the gnulib module fprintf should be tested. */
+#undef GNULIB_TEST_FPRINTF
+
+/* Define to 1 when the gnulib module fputc should be tested. */
+#undef GNULIB_TEST_FPUTC
+
+/* Define to 1 when the gnulib module fputs should be tested. */
+#undef GNULIB_TEST_FPUTS
+
+/* Define to 1 when the gnulib module fread should be tested. */
+#undef GNULIB_TEST_FREAD
+
 /* Define to 1 when the gnulib module free-posix should be tested. */
 #undef GNULIB_TEST_FREE_POSIX
 
@@ -207,12 +229,24 @@
 /* Define to 1 when the gnulib module frexpl should be tested. */
 #undef GNULIB_TEST_FREXPL
 
+/* Define to 1 when the gnulib module fscanf should be tested. */
+#undef GNULIB_TEST_FSCANF
+
 /* Define to 1 when the gnulib module fstat should be tested. */
 #undef GNULIB_TEST_FSTAT
 
 /* Define to 1 when the gnulib module fstatat should be tested. */
 #undef GNULIB_TEST_FSTATAT
 
+/* Define to 1 when the gnulib module fwrite should be tested. */
+#undef GNULIB_TEST_FWRITE
+
+/* Define to 1 when the gnulib module getc should be tested. */
+#undef GNULIB_TEST_GETC
+
+/* Define to 1 when the gnulib module getchar should be tested. */
+#undef GNULIB_TEST_GETCHAR
+
 /* Define to 1 when the gnulib module getcwd should be tested. */
 #undef GNULIB_TEST_GETCWD
 
@@ -291,6 +325,18 @@
 /* Define to 1 when the gnulib module pipe should be tested. */
 #undef GNULIB_TEST_PIPE
 
+/* Define to 1 when the gnulib module printf should be tested. */
+#undef GNULIB_TEST_PRINTF
+
+/* Define to 1 when the gnulib module putc should be tested. */
+#undef GNULIB_TEST_PUTC
+
+/* Define to 1 when the gnulib module putchar should be tested. */
+#undef GNULIB_TEST_PUTCHAR
+
+/* Define to 1 when the gnulib module puts should be tested. */
+#undef GNULIB_TEST_PUTS
+
 /* Define to 1 when the gnulib module rawmemchr should be tested. */
 #undef GNULIB_TEST_RAWMEMCHR
 
@@ -315,6 +361,9 @@
 /* Define to 1 when the gnulib module rmdir should be tested. */
 #undef GNULIB_TEST_RMDIR
 
+/* Define to 1 when the gnulib module scanf should be tested. */
+#undef GNULIB_TEST_SCANF
+
 /* Define to 1 when the gnulib module select should be tested. */
 #undef GNULIB_TEST_SELECT
 
@@ -360,6 +409,12 @@
 /* Define to 1 when the gnulib module unsetenv should be tested. */
 #undef GNULIB_TEST_UNSETENV
 
+/* Define to 1 when the gnulib module vfprintf should be tested. */
+#undef GNULIB_TEST_VFPRINTF
+
+/* Define to 1 when the gnulib module vprintf should be tested. */
+#undef GNULIB_TEST_VPRINTF
+
 /* Define to 1 when the gnulib module wmemchr should be tested. */
 #undef GNULIB_TEST_WMEMCHR
 
@@ -395,6 +450,9 @@
 /* Define to 1 if you have the `chown' function. */
 #undef HAVE_CHOWN
 
+/* Define to 1 if you have the `clock_getres' function. */
+#undef HAVE_CLOCK_GETRES
+
 /* Define to 1 if you have the `clock_gettime' function. */
 #undef HAVE_CLOCK_GETTIME
 
@@ -407,6 +465,9 @@
 /* Define to 1 if you have the <crtdefs.h> header file. */
 #undef HAVE_CRTDEFS_H
 
+/* Define to 1 if C supports variable-length arrays. */
+#undef HAVE_C_VARARRAYS
+
 /* Define to 1 if you have the declaration of `alarm', and to 0 if you don't.
    */
 #undef HAVE_DECL_ALARM
@@ -582,6 +643,9 @@
 /* Define to 1 if you have the <fnmatch.h> header file. */
 #undef HAVE_FNMATCH_H
 
+/* Define if the 'free' function is guaranteed to preserve errno. */
+#undef HAVE_FREE_POSIX
+
 /* Define if the frexp() function is available and works. */
 #undef HAVE_FREXP
 
@@ -682,7 +746,7 @@
 /* Define to 1 if you have the `lstat' function. */
 #undef HAVE_LSTAT
 
-/* Define if the 'malloc' function is POSIX compliant. */
+/* Define if malloc, realloc, and calloc set errno on allocation failure. */
 #undef HAVE_MALLOC_POSIX
 
 /* Define to 1 if mmap()'s MAP_ANONYMOUS flag is available after including
@@ -786,9 +850,6 @@
 /* Define to 1 if you have the `readlink' function. */
 #undef HAVE_READLINK
 
-/* Define if the 'realloc' function is POSIX compliant. */
-#undef HAVE_REALLOC_POSIX
-
 /* Define to 1 if you have the `realpath' function. */
 #undef HAVE_REALPATH
 
@@ -1007,6 +1068,114 @@
 #endif
     
 
+/* Define to 1 if ctype.h defines __header_inline. */
+#undef HAVE___HEADER_INLINE
+
+/* Please see the Gnulib manual for how to use these macros.
+
+   Suppress extern inline with HP-UX cc, as it appears to be broken; see
+   <https://lists.gnu.org/r/bug-texinfo/2013-02/msg00030.html>.
+
+   Suppress extern inline with Sun C in standards-conformance mode, as it
+   mishandles inline functions that call each other.  E.g., for 'inline void f
+   (void) { } inline void g (void) { f (); }', c99 incorrectly complains
+   'reference to static identifier "f" in extern inline function'.
+   This bug was observed with Oracle Developer Studio 12.6
+   (Sun C 5.15 SunOS_sparc 2017/05/30).
+
+   Suppress extern inline (with or without __attribute__ ((__gnu_inline__)))
+   on configurations that mistakenly use 'static inline' to implement
+   functions or macros in standard C headers like <ctype.h>.  For example,
+   if isdigit is mistakenly implemented via a static inline function,
+   a program containing an extern inline function that calls isdigit
+   may not work since the C standard prohibits extern inline functions
+   from calling static functions (ISO C 99 section 6.7.4.(3).
+   This bug is known to occur on:
+
+     OS X 10.8 and earlier; see:
+     https://lists.gnu.org/r/bug-gnulib/2012-12/msg00023.html
+
+     DragonFly; see
+     http://muscles.dragonflybsd.org/bulk/clang-master-potential/20141111_102002/logs/ah-tty-0.3.12.log
+
+     FreeBSD; see:
+     https://lists.gnu.org/r/bug-gnulib/2014-07/msg00104.html
+
+   OS X 10.9 has a macro __header_inline indicating the bug is fixed for C and
+   for clang but remains for g++; see <https://trac.macports.org/ticket/41033>.
+   Assume DragonFly and FreeBSD will be similar.
+
+   GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
+   inline semantics, unless -fgnu89-inline is used.  It defines a macro
+   __GNUC_STDC_INLINE__ to indicate this situation or a macro
+   __GNUC_GNU_INLINE__ to indicate the opposite situation.
+   GCC 4.2 with -std=c99 or -std=gnu99 implements the GNU C inline
+   semantics but warns, unless -fgnu89-inline is used:
+     warning: C99 inline functions are not supported; using GNU89
+     warning: to disable this warning use -fgnu89-inline or the gnu_inline function attribute
+   It defines a macro __GNUC_GNU_INLINE__ to indicate this situation.
+ */
+#if (((defined __APPLE__ && defined __MACH__) \
+      || defined __DragonFly__ || defined __FreeBSD__) \
+     && (defined HAVE___HEADER_INLINE \
+         ? (defined __cplusplus && defined __GNUC_STDC_INLINE__ \
+            && ! defined __clang__) \
+         : ((! defined _DONT_USE_CTYPE_INLINE_ \
+             && (defined __GNUC__ || defined __cplusplus)) \
+            || (defined _FORTIFY_SOURCE && 0 < _FORTIFY_SOURCE \
+                && defined __GNUC__ && ! defined __cplusplus))))
+# define _GL_EXTERN_INLINE_STDHEADER_BUG
+#endif
+#if ((__GNUC__ \
+      ? defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__ \
+      : (199901L <= __STDC_VERSION__ \
+         && !defined __HP_cc \
+         && !defined __PGI \
+         && !(defined __SUNPRO_C && __STDC__))) \
+     && !defined _GL_EXTERN_INLINE_STDHEADER_BUG)
+# define _GL_INLINE inline
+# define _GL_EXTERN_INLINE extern inline
+# define _GL_EXTERN_INLINE_IN_USE
+#elif (2 < __GNUC__ + (7 <= __GNUC_MINOR__) && !defined __STRICT_ANSI__ \
+       && !defined _GL_EXTERN_INLINE_STDHEADER_BUG)
+# if defined __GNUC_GNU_INLINE__ && __GNUC_GNU_INLINE__
+   /* __gnu_inline__ suppresses a GCC 4.2 diagnostic.  */
+#  define _GL_INLINE extern inline __attribute__ ((__gnu_inline__))
+# else
+#  define _GL_INLINE extern inline
+# endif
+# define _GL_EXTERN_INLINE extern
+# define _GL_EXTERN_INLINE_IN_USE
+#else
+# define _GL_INLINE _GL_UNUSED static
+# define _GL_EXTERN_INLINE _GL_UNUSED static
+#endif
+
+/* In GCC 4.6 (inclusive) to 5.1 (exclusive),
+   suppress bogus "no previous prototype for 'FOO'"
+   and "no previous declaration for 'FOO'" diagnostics,
+   when FOO is an inline function in the header; see
+   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113> and
+   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63877>.  */
+#if __GNUC__ == 4 && 6 <= __GNUC_MINOR__
+# if defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__
+#  define _GL_INLINE_HEADER_CONST_PRAGMA
+# else
+#  define _GL_INLINE_HEADER_CONST_PRAGMA \
+     _Pragma ("GCC diagnostic ignored \"-Wsuggest-attribute=const\"")
+# endif
+# define _GL_INLINE_HEADER_BEGIN \
+    _Pragma ("GCC diagnostic push") \
+    _Pragma ("GCC diagnostic ignored \"-Wmissing-prototypes\"") \
+    _Pragma ("GCC diagnostic ignored \"-Wmissing-declarations\"") \
+    _GL_INLINE_HEADER_CONST_PRAGMA
+# define _GL_INLINE_HEADER_END \
+    _Pragma ("GCC diagnostic pop")
+#else
+# define _GL_INLINE_HEADER_BEGIN
+# define _GL_INLINE_HEADER_END
+#endif
+
 /* Define to 1 if the compiler supports the keyword '__inline'. */
 #undef HAVE___INLINE
 
@@ -1177,6 +1346,10 @@
 /* Define if the POSIX multithreading library can be used. */
 #undef USE_POSIX_THREADS
 
+/* Define if references to the POSIX multithreading library are satisfied by
+   libc. */
+#undef USE_POSIX_THREADS_FROM_LIBC
+
 /* Define if references to the POSIX multithreading library should be made
    weak. */
 #undef USE_POSIX_THREADS_WEAK
@@ -1333,11 +1506,12 @@
        this syntax with 'extern'.  */
 #  define _Noreturn [[noreturn]]
 # elif ((!defined __cplusplus || defined __clang__) \
-        && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0)  \
-            || _GL_GNUC_PREREQ (4, 7) \
-            || (defined __apple_build_version__ \
-                ? 6000000 <= __apple_build_version__ \
-                : 3 < __clang_major__ + (5 <= __clang_minor__))))
+        && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
+            || (!defined __STRICT_ANSI__ \
+                && (_GL_GNUC_PREREQ (4, 7) \
+                    || (defined __apple_build_version__ \
+                        ? 6000000 <= __apple_build_version__ \
+                        : 3 < __clang_major__ + (5 <= __clang_minor__))))))
    /* _Noreturn works as-is.  */
 # elif _GL_GNUC_PREREQ (2, 8) || defined __clang__ || 0x5110 <= __SUNPRO_C
 #  define _Noreturn __attribute__ ((__noreturn__))
@@ -1353,15 +1527,25 @@
    functions. */
 #undef _POSIX_PII_SOCKET
 
+/* Number of bits in a timestamp, on hosts where this is settable. */
+#undef _TIME_BITS
+
 /* For standard stat data types on VMS. */
 #undef _USE_STD_STAT
 
+/* For 64-bit time_t on 32-bit mingw. */
+#undef __MINGW_USE_VC2005_COMPAT
+
 /* Define to 1 if the system <stdint.h> predates C++11. */
 #undef __STDC_CONSTANT_MACROS
 
 /* Define to 1 if the system <stdint.h> predates C++11. */
 #undef __STDC_LIMIT_MACROS
 
+/* Define to 1 if C does not support variable-length arrays, and if the
+   compiler does not already define this. */
+#undef __STDC_NO_VLA__
+
 /* The _GL_ASYNC_SAFE marker should be attached to functions that are
    signal handlers (for signals other than SIGABRT, SIGPIPE) or can be
    invoked from such signal handlers.  Such functions have some restrictions:
@@ -1390,7 +1574,11 @@
 
 
 /* Attributes.  */
-#ifdef __has_attribute
+#if (defined __has_attribute \
+     && (!defined __clang_minor__ \
+         || (defined __apple_build_version__ \
+             ? 6000000 <= __apple_build_version__ \
+             : 3 < __clang_major__ + (5 <= __clang_minor__))))
 # define _GL_HAS_ATTRIBUTE(attr) __has_attribute (__##attr##__)
 #else
 # define _GL_HAS_ATTRIBUTE(attr) _GL_ATTR_##attr
@@ -1406,12 +1594,12 @@
 # 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)
+# define _GL_ATTR_malloc _GL_GNUC_PREREQ (3, 0)
 # 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)
@@ -1424,25 +1612,46 @@
 # define _GL_ATTR_warn_unused_result _GL_GNUC_PREREQ (3, 4)
 #endif
 
+#ifdef __has_c_attribute
+# define _GL_HAS_C_ATTRIBUTE(attr) __has_c_attribute (__##attr##__)
+#else
+# define _GL_HAS_C_ATTRIBUTE(attr) 0
+#endif
 
+
+/* _GL_ATTRIBUTE_ALLOC_SIZE ((N)) declares that the Nth argument of the function
+   is the size of the returned memory block.
+   _GL_ATTRIBUTE_ALLOC_SIZE ((M, N)) declares that the Mth argument multiplied
+   by the Nth argument of the function is the size of the returned memory block.
+ */
+/* Applies to: function, pointer to function, function types.  */
 #if _GL_HAS_ATTRIBUTE (alloc_size)
 # define _GL_ATTRIBUTE_ALLOC_SIZE(args) __attribute__ ((__alloc_size__ args))
 #else
 # define _GL_ATTRIBUTE_ALLOC_SIZE(args)
 #endif
 
+/* _GL_ATTRIBUTE_ALWAYS_INLINE tells that the compiler should always inline the
+   function and report an error if it cannot do so.  */
+/* Applies to: function.  */
 #if _GL_HAS_ATTRIBUTE (always_inline)
 # define _GL_ATTRIBUTE_ALWAYS_INLINE __attribute__ ((__always_inline__))
 #else
 # define _GL_ATTRIBUTE_ALWAYS_INLINE
 #endif
 
+/* _GL_ATTRIBUTE_ARTIFICIAL declares that the function is not important to show
+    in stack traces when debugging.  The compiler should omit the function from
+    stack traces.  */
+/* Applies to: function.  */
 #if _GL_HAS_ATTRIBUTE (artificial)
 # define _GL_ATTRIBUTE_ARTIFICIAL __attribute__ ((__artificial__))
 #else
 # define _GL_ATTRIBUTE_ARTIFICIAL
 #endif
 
+/* _GL_ATTRIBUTE_COLD declares that the function is rarely executed.  */
+/* Applies to: functions.  */
 /* Avoid __attribute__ ((cold)) on MinGW; see thread starting at
    <https://lists.gnu.org/r/emacs-devel/2019-04/msg01152.html>.
    Also, Oracle Studio 12.6 requires 'cold' not '__cold__'.  */
@@ -1456,13 +1665,46 @@
 # define _GL_ATTRIBUTE_COLD
 #endif
 
+/* _GL_ATTRIBUTE_CONST declares that it is OK for a compiler to omit duplicate
+   calls to the function with the same arguments.
+   This attribute is safe for a function that neither depends on nor affects
+   observable state, and always returns exactly once - e.g., does not loop
+   forever, and does not call longjmp.
+   (This attribute is stricter than _GL_ATTRIBUTE_PURE.)  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (const)
 # define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
 #else
 # define _GL_ATTRIBUTE_CONST
 #endif
 
-#if 201710L < __STDC_VERSION__
+/* _GL_ATTRIBUTE_DEALLOC (F, I) declares that the function returns pointers
+   that can be freed by passing them as the Ith argument to the
+   function F.
+   _GL_ATTRIBUTE_DEALLOC_FREE declares that the function returns pointers that
+   can be freed via 'free'; it can be used only after declaring 'free'.  */
+/* Applies to: functions.  Cannot be used on inline functions.  */
+#if _GL_GNUC_PREREQ (11, 0)
+# define _GL_ATTRIBUTE_DEALLOC(f, i) __attribute__ ((__malloc__ (f, i)))
+#else
+# define _GL_ATTRIBUTE_DEALLOC(f, i)
+#endif
+/* If gnulib's <string.h> or <wchar.h> has already defined this macro, continue
+   to use this earlier definition, since <stdlib.h> may not have been included
+   yet.  */
+#ifndef _GL_ATTRIBUTE_DEALLOC_FREE
+# define _GL_ATTRIBUTE_DEALLOC_FREE _GL_ATTRIBUTE_DEALLOC (free, 1)
+#endif
+
+/* _GL_ATTRIBUTE_DEPRECATED: Declares that an entity is deprecated.
+   The compiler may warn if the entity is used.  */
+/* Applies to:
+     - function, variable,
+     - struct, union, struct/union member,
+     - enumeration, enumeration item,
+     - typedef,
+   in C++ also: namespace, class, template specialization.  */
+#if _GL_HAS_C_ATTRIBUTE (deprecated)
 # define _GL_ATTRIBUTE_DEPRECATED [[__deprecated__]]
 #elif _GL_HAS_ATTRIBUTE (deprecated)
 # define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
@@ -1470,6 +1712,11 @@
 # define _GL_ATTRIBUTE_DEPRECATED
 #endif
 
+/* _GL_ATTRIBUTE_ERROR(msg) requests an error if a function is called and
+   the function call is not optimized away.
+   _GL_ATTRIBUTE_WARNING(msg) requests a warning if a function is called and
+   the function call is not optimized away.  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (error)
 # define _GL_ATTRIBUTE_ERROR(msg) __attribute__ ((__error__ (msg)))
 # define _GL_ATTRIBUTE_WARNING(msg) __attribute__ ((__warning__ (msg)))
@@ -1481,14 +1728,21 @@
 # define _GL_ATTRIBUTE_WARNING(msg)
 #endif
 
+/* _GL_ATTRIBUTE_EXTERNALLY_VISIBLE declares that the entity should remain
+   visible to debuggers etc., even with '-fwhole-program'.  */
+/* Applies to: functions, variables.  */
 #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__
+/* _GL_ATTRIBUTE_FALLTHROUGH declares that it is not a programming mistake if
+   the control flow falls through to the immediately following 'case' or
+   'default' label.  The compiler should not warn in this case.  */
+/* Applies to: Empty statement (;), inside a 'switch' statement.  */
+/* Always expands to something.  */
+#if _GL_HAS_C_ATTRIBUTE (fallthrough)
 # define _GL_ATTRIBUTE_FALLTHROUGH [[__fallthrough__]]
 #elif _GL_HAS_ATTRIBUTE (fallthrough)
 # define _GL_ATTRIBUTE_FALLTHROUGH __attribute__ ((__fallthrough__))
@@ -1496,18 +1750,47 @@
 # define _GL_ATTRIBUTE_FALLTHROUGH ((void) 0)
 #endif
 
+/* _GL_ATTRIBUTE_FORMAT ((ARCHETYPE, STRING-INDEX, FIRST-TO-CHECK))
+   declares that the STRING-INDEXth function argument is a format string of
+   style ARCHETYPE, which is one of:
+     printf, gnu_printf
+     scanf, gnu_scanf,
+     strftime, gnu_strftime,
+     strfmon,
+   or the same thing prefixed and suffixed with '__'.
+   If FIRST-TO-CHECK is not 0, arguments starting at FIRST-TO_CHECK
+   are suitable for the format string.  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (format)
 # define _GL_ATTRIBUTE_FORMAT(spec) __attribute__ ((__format__ spec))
 #else
 # define _GL_ATTRIBUTE_FORMAT(spec)
 #endif
 
+/* _GL_ATTRIBUTE_LEAF declares that if the function is called from some other
+   compilation unit, it executes code from that unit only by return or by
+   exception handling.  This declaration lets the compiler optimize that unit
+   more aggressively.  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (leaf)
 # define _GL_ATTRIBUTE_LEAF __attribute__ ((__leaf__))
 #else
 # define _GL_ATTRIBUTE_LEAF
 #endif
 
+/* _GL_ATTRIBUTE_MALLOC declares that the function returns a pointer to freshly
+   allocated memory.  */
+/* Applies to: functions.  */
+#if _GL_HAS_ATTRIBUTE (malloc)
+# define _GL_ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
+#else
+# define _GL_ATTRIBUTE_MALLOC
+#endif
+
+/* _GL_ATTRIBUTE_MAY_ALIAS declares that pointers to the type may point to the
+   same storage as pointers to other types.  Thus this declaration disables
+   strict aliasing optimization.  */
+/* Applies to: types.  */
 /* Oracle Studio 12.6 mishandles may_alias despite __has_attribute OK.  */
 #if _GL_HAS_ATTRIBUTE (may_alias) && !defined __SUNPRO_C
 # define _GL_ATTRIBUTE_MAY_ALIAS __attribute__ ((__may_alias__))
@@ -1515,24 +1798,33 @@
 # define _GL_ATTRIBUTE_MAY_ALIAS
 #endif
 
-#if 201710L < __STDC_VERSION__
+/* _GL_ATTRIBUTE_MAYBE_UNUSED declares that it is not a programming mistake if
+   the entity is not used.  The compiler should not warn if the entity is not
+   used.  */
+/* Applies to:
+     - function, variable,
+     - struct, union, struct/union member,
+     - enumeration, enumeration item,
+     - typedef,
+   in C++ also: class.  */
+/* In C++ and C2x, this is spelled [[__maybe_unused__]].
+   GCC's syntax is __attribute__ ((__unused__)).
+   clang supports both syntaxes.  */
+#if _GL_HAS_C_ATTRIBUTE (maybe_unused)
 # 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
+# define _GL_ATTRIBUTE_MAYBE_UNUSED _GL_ATTRIBUTE_UNUSED
 #endif
-/* Earlier spellings of this macro.  */
+/* Alternative spelling of this macro, for convenience.  */
 #define _GL_UNUSED _GL_ATTRIBUTE_MAYBE_UNUSED
+/* Earlier spellings of this macro.  */
 #define _UNUSED_PARAMETER_ _GL_ATTRIBUTE_MAYBE_UNUSED
 
-#if _GL_HAS_ATTRIBUTE (malloc)
-# define _GL_ATTRIBUTE_MALLOC __attribute__ ((__malloc__))
-#else
-# define _GL_ATTRIBUTE_MALLOC
-#endif
-
-#if 201710L < __STDC_VERSION__
+/* _GL_ATTRIBUTE_NODISCARD declares that the caller of the function should not
+   discard the return value.  The compiler may warn if the caller does not use
+   the return value, unless the caller uses something like ignore_value.  */
+/* Applies to: function, enumeration, class.  */
+#if _GL_HAS_C_ATTRIBUTE (nodiscard)
 # define _GL_ATTRIBUTE_NODISCARD [[__nodiscard__]]
 #elif _GL_HAS_ATTRIBUTE (warn_unused_result)
 # define _GL_ATTRIBUTE_NODISCARD __attribute__ ((__warn_unused_result__))
@@ -1540,18 +1832,30 @@
 # define _GL_ATTRIBUTE_NODISCARD
 #endif
 
+/* _GL_ATTRIBUTE_NOINLINE tells that the compiler should not inline the
+   function.  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (noinline)
 # define _GL_ATTRIBUTE_NOINLINE __attribute__ ((__noinline__))
 #else
 # define _GL_ATTRIBUTE_NOINLINE
 #endif
 
+/* _GL_ATTRIBUTE_NONNULL ((N1, N2,...)) declares that the arguments N1, N2,...
+   must not be NULL.
+   _GL_ATTRIBUTE_NONNULL () declares that all pointer arguments must not be
+   null.  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (nonnull)
 # define _GL_ATTRIBUTE_NONNULL(args) __attribute__ ((__nonnull__ args))
 #else
 # define _GL_ATTRIBUTE_NONNULL(args)
 #endif
 
+/* _GL_ATTRIBUTE_NONSTRING declares that the contents of a character array is
+   not meant to be NUL-terminated.  */
+/* Applies to: struct/union members and variables that are arrays of element
+   type '[[un]signed] char'.  */
 #if _GL_HAS_ATTRIBUTE (nonstring)
 # define _GL_ATTRIBUTE_NONSTRING __attribute__ ((__nonstring__))
 #else
@@ -1560,148 +1864,80 @@
 
 /* There is no _GL_ATTRIBUTE_NORETURN; use _Noreturn instead.  */
 
+/* _GL_ATTRIBUTE_NOTHROW declares that the function does not throw exceptions.
+ */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (nothrow) && !defined __cplusplus
 # define _GL_ATTRIBUTE_NOTHROW __attribute__ ((__nothrow__))
 #else
 # define _GL_ATTRIBUTE_NOTHROW
 #endif
 
+/* _GL_ATTRIBUTE_PACKED declares:
+   For struct members: The member has the smallest possible alignment.
+   For struct, union, class: All members have the smallest possible alignment,
+   minimizing the memory required.  */
+/* Applies to: struct members, struct, union,
+   in C++ also: class.  */
 #if _GL_HAS_ATTRIBUTE (packed)
 # define _GL_ATTRIBUTE_PACKED __attribute__ ((__packed__))
 #else
 # define _GL_ATTRIBUTE_PACKED
 #endif
 
+/* _GL_ATTRIBUTE_PURE declares that It is OK for a compiler to omit duplicate
+   calls to the function with the same arguments if observable state is not
+   changed between calls.
+   This attribute is safe for a function that does not affect
+   observable state, and always returns exactly once.
+   (This attribute is looser than _GL_ATTRIBUTE_CONST.)  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (pure)
 # define _GL_ATTRIBUTE_PURE __attribute__ ((__pure__))
 #else
 # define _GL_ATTRIBUTE_PURE
 #endif
 
+/* _GL_ATTRIBUTE_RETURNS_NONNULL declares that the function's return value is
+   a non-NULL pointer.  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (returns_nonnull)
 # define _GL_ATTRIBUTE_RETURNS_NONNULL __attribute__ ((__returns_nonnull__))
 #else
 # define _GL_ATTRIBUTE_RETURNS_NONNULL
 #endif
 
+/* _GL_ATTRIBUTE_SENTINEL(pos) declares that the variadic function expects a
+   trailing NULL argument.
+   _GL_ATTRIBUTE_SENTINEL () - The last argument is NULL (requires C99).
+   _GL_ATTRIBUTE_SENTINEL ((N)) - The (N+1)st argument from the end is NULL.  */
+/* Applies to: functions.  */
 #if _GL_HAS_ATTRIBUTE (sentinel)
 # define _GL_ATTRIBUTE_SENTINEL(pos) __attribute__ ((__sentinel__ pos))
 #else
 # define _GL_ATTRIBUTE_SENTINEL(pos)
 #endif
 
-
-/* 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
+/* A helper macro.  Don't use it directly.  */
+#if _GL_HAS_ATTRIBUTE (unused)
+# define _GL_ATTRIBUTE_UNUSED __attribute__ ((__unused__))
 #else
-# define _GL_UNUSED_LABEL
+# define _GL_ATTRIBUTE_UNUSED
 #endif
 
 
-/* Please see the Gnulib manual for how to use these macros.
-
-   Suppress extern inline with HP-UX cc, as it appears to be broken; see
-   <https://lists.gnu.org/r/bug-texinfo/2013-02/msg00030.html>.
-
-   Suppress extern inline with Sun C in standards-conformance mode, as it
-   mishandles inline functions that call each other.  E.g., for 'inline void f
-   (void) { } inline void g (void) { f (); }', c99 incorrectly complains
-   'reference to static identifier "f" in extern inline function'.
-   This bug was observed with Sun C 5.12 SunOS_i386 2011/11/16.
-
-   Suppress extern inline (with or without __attribute__ ((__gnu_inline__)))
-   on configurations that mistakenly use 'static inline' to implement
-   functions or macros in standard C headers like <ctype.h>.  For example,
-   if isdigit is mistakenly implemented via a static inline function,
-   a program containing an extern inline function that calls isdigit
-   may not work since the C standard prohibits extern inline functions
-   from calling static functions (ISO C 99 section 6.7.4.(3).
-   This bug is known to occur on:
-
-     OS X 10.8 and earlier; see:
-     https://lists.gnu.org/r/bug-gnulib/2012-12/msg00023.html
-
-     DragonFly; see
-     http://muscles.dragonflybsd.org/bulk/clang-master-potential/20141111_102002/logs/ah-tty-0.3.12.log
-
-     FreeBSD; see:
-     https://lists.gnu.org/r/bug-gnulib/2014-07/msg00104.html
-
-   OS X 10.9 has a macro __header_inline indicating the bug is fixed for C and
-   for clang but remains for g++; see <https://trac.macports.org/ticket/41033>.
-   Assume DragonFly and FreeBSD will be similar.
-
-   GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
-   inline semantics, unless -fgnu89-inline is used.  It defines a macro
-   __GNUC_STDC_INLINE__ to indicate this situation or a macro
-   __GNUC_GNU_INLINE__ to indicate the opposite situation.
-   GCC 4.2 with -std=c99 or -std=gnu99 implements the GNU C inline
-   semantics but warns, unless -fgnu89-inline is used:
-     warning: C99 inline functions are not supported; using GNU89
-     warning: to disable this warning use -fgnu89-inline or the gnu_inline function attribute
-   It defines a macro __GNUC_GNU_INLINE__ to indicate this situation.
- */
-#if (((defined __APPLE__ && defined __MACH__) \
-      || defined __DragonFly__ || defined __FreeBSD__) \
-     && (defined __header_inline \
-         ? (defined __cplusplus && defined __GNUC_STDC_INLINE__ \
-            && ! defined __clang__) \
-         : ((! defined _DONT_USE_CTYPE_INLINE_ \
-             && (defined __GNUC__ || defined __cplusplus)) \
-            || (defined _FORTIFY_SOURCE && 0 < _FORTIFY_SOURCE \
-                && defined __GNUC__ && ! defined __cplusplus))))
-# define _GL_EXTERN_INLINE_STDHEADER_BUG
-#endif
-#if ((__GNUC__ \
-      ? defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__ \
-      : (199901L <= __STDC_VERSION__ \
-         && !defined __HP_cc \
-         && !defined __PGI \
-         && !(defined __SUNPRO_C && __STDC__))) \
-     && !defined _GL_EXTERN_INLINE_STDHEADER_BUG)
-# define _GL_INLINE inline
-# define _GL_EXTERN_INLINE extern inline
-# define _GL_EXTERN_INLINE_IN_USE
-#elif (2 < __GNUC__ + (7 <= __GNUC_MINOR__) && !defined __STRICT_ANSI__ \
-       && !defined _GL_EXTERN_INLINE_STDHEADER_BUG)
-# if defined __GNUC_GNU_INLINE__ && __GNUC_GNU_INLINE__
-   /* __gnu_inline__ suppresses a GCC 4.2 diagnostic.  */
-#  define _GL_INLINE extern inline __attribute__ ((__gnu_inline__))
-# else
-#  define _GL_INLINE extern inline
-# endif
-# define _GL_EXTERN_INLINE extern
-# define _GL_EXTERN_INLINE_IN_USE
+/* _GL_UNUSED_LABEL; declares that it is not a programming mistake if the
+   immediately preceding label is not used.  The compiler should not warn
+   if the label is not used.  */
+/* Applies to: label (both in C and C++).  */
+/* Note that g++ < 4.5 does not support the '__attribute__ ((__unused__)) ;'
+   syntax.  But clang does.  */
+#if !(defined __cplusplus && !_GL_GNUC_PREREQ (4, 5)) || defined __clang__
+# define _GL_UNUSED_LABEL _GL_ATTRIBUTE_UNUSED
 #else
-# define _GL_INLINE static _GL_UNUSED
-# define _GL_EXTERN_INLINE static _GL_UNUSED
+# define _GL_UNUSED_LABEL
 #endif
 
-/* In GCC 4.6 (inclusive) to 5.1 (exclusive),
-   suppress bogus "no previous prototype for 'FOO'"
-   and "no previous declaration for 'FOO'" diagnostics,
-   when FOO is an inline function in the header; see
-   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54113> and
-   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63877>.  */
-#if __GNUC__ == 4 && 6 <= __GNUC_MINOR__
-# if defined __GNUC_STDC_INLINE__ && __GNUC_STDC_INLINE__
-#  define _GL_INLINE_HEADER_CONST_PRAGMA
-# else
-#  define _GL_INLINE_HEADER_CONST_PRAGMA \
-     _Pragma ("GCC diagnostic ignored \"-Wsuggest-attribute=const\"")
-# endif
-# define _GL_INLINE_HEADER_BEGIN \
-    _Pragma ("GCC diagnostic push") \
-    _Pragma ("GCC diagnostic ignored \"-Wmissing-prototypes\"") \
-    _Pragma ("GCC diagnostic ignored \"-Wmissing-declarations\"") \
-    _GL_INLINE_HEADER_CONST_PRAGMA
-# define _GL_INLINE_HEADER_END \
-    _Pragma ("GCC diagnostic pop")
-#else
-# define _GL_INLINE_HEADER_BEGIN
-# define _GL_INLINE_HEADER_END
-#endif
 
 /* Define to `int' if <sys/types.h> doesn't define. */
 #undef gid_t