gnulib-common: update for C2x 2020-12-11 draft

Use blessed-by-draft-standard way to test for [[__deprecated__]]
etc.; this is supported by GCC 11 and the fallback code should
work fine with GCC 10 and earlier, clang, etc.
* NEWS, doc/attribute.texi:
Mention that DEPRECATED etc. must now come first.
* lib/fflush.c, lib/unistr.in.h:
Do not include unused-parameter.h.  All uses of _GL_UNUSED_PARAMETER
(after parameters) replaced by _GL_ATTRIBUTE_MAYBE_UNUSED (before
parameters).  Although perhaps we need a shorter name for
_GL_ATTRIBUTE_MAYBE_UNUSED, that should probably be in
gnulib-common.m4, due to the ubiquity of this issue.
And perhaps the snippet/unused-parameter module should be marked
obsolete since it's no longer compatible with its old use.
* m4/gnulib-common.m4 (gl_COMMON_BODY): Define the macro
_GL_HAS_C_ATTRIBUTE, and use it instead of __STDC_VERSION__ in
deciding whether to use C2x attributes like [[__deprecated__]].
(_GL_ATTRIBUTE_MAYBE_UNUSED): Fall back on _GL_ATTRIBUTE_UNUSED.
(_GL_ATTRIBUTE_UNUSED): New macro, for labels where C2x
[[maybe_unused]] do not work.
(_GL_UNUSED, _GL_UNUSED_LABEL): Use it.
* modules/fflush, modules/unistr/base (Depends-on):
Remove snippet/unused-parameter.
* modules/fflush (selinux/selinux.h, selinux/context.h)
(selinux/label.h): Do not use $(UNUSED_PARAMETER).
Remove useless chmod a-x.

1 files changed, 6 insertions, 6 deletions

diff --git a/lib/gl_omap.h b/lib/gl_omap.h
index ca6916c82f..b2dacfb283 100644
--- a/lib/gl_omap.h
+++ b/lib/gl_omap.h
@@ -155,8 +155,8 @@ extern bool gl_omap_search_atleast (gl_omap_t map,
 /* declared in gl_xomap.h */
 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)
-  _GL_ATTRIBUTE_NODISCARD;
+_GL_ATTRIBUTE_NODISCARD
+extern int gl_omap_nx_put (gl_omap_t map, const void *key, const void *value);
 
 /* 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
@@ -167,9 +167,9 @@ extern int gl_omap_nx_put (gl_omap_t map, const void *key, const void *value)
 extern bool gl_omap_getput (gl_omap_t map, const void *key, const void *value,
                             const void **oldvaluep);
 /* Likewise.  Returns -1 upon out-of-memory.  */
+_GL_ATTRIBUTE_NODISCARD
 extern int gl_omap_nx_getput (gl_omap_t map, const void *key, const void *value,
-                              const void **oldvaluep)
-  _GL_ATTRIBUTE_NODISCARD;
+                              const void **oldvaluep);
 
 /* Removes a pair from an ordered map.
    Returns true if the key was found and its pair removed.
@@ -298,7 +298,7 @@ gl_omap_search_atleast (gl_omap_t map,
          ->search_atleast (map, threshold_fn, threshold, keyp, valuep);
 }
 
-GL_OMAP_INLINE _GL_ATTRIBUTE_NODISCARD int
+_GL_ATTRIBUTE_NODISCARD GL_OMAP_INLINE int
 gl_omap_nx_getput (gl_omap_t map, const void *key, const void *value,
                    const void **oldvaluep)
 {
@@ -349,7 +349,7 @@ gl_omap_get (gl_omap_t map, const void *key)
   return value;
 }
 
-GL_OMAP_INLINE _GL_ATTRIBUTE_NODISCARD int
+_GL_ATTRIBUTE_NODISCARD GL_OMAP_INLINE int
 gl_omap_nx_put (gl_omap_t map, const void *key, const void *value)
 {
   const void *oldvalue;