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, 25 insertions, 17 deletions

diff --git a/lib/se-context.in.h b/lib/se-context.in.h
index 999a7b413c..d4ed6a4c1a 100644
--- a/lib/se-context.in.h
+++ b/lib/se-context.in.h
@@ -29,34 +29,42 @@ _GL_INLINE_HEADER_BEGIN
 # define SE_CONTEXT_INLINE _GL_INLINE
 #endif
 
-/* The definition of _GL_UNUSED_PARAMETER is copied here.  */
-
 typedef int context_t;
-SE_CONTEXT_INLINE context_t context_new (char const *s _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE context_t
+context_new (_GL_ATTRIBUTE_MAYBE_UNUSED char const *s)
   { errno = ENOTSUP; return 0; }
-SE_CONTEXT_INLINE char *context_str (context_t con _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE char *
+context_str (_GL_ATTRIBUTE_MAYBE_UNUSED context_t con)
   { errno = ENOTSUP; return (void *) 0; }
-SE_CONTEXT_INLINE void context_free (context_t c _GL_UNUSED_PARAMETER) {}
+SE_CONTEXT_INLINE void context_free (_GL_ATTRIBUTE_MAYBE_UNUSED context_t c) {}
 
-SE_CONTEXT_INLINE int context_user_set (context_t sc _GL_UNUSED_PARAMETER,
-                                        char const *s _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE int
+context_user_set (_GL_ATTRIBUTE_MAYBE_UNUSED context_t sc,
+                  _GL_ATTRIBUTE_MAYBE_UNUSED char const *s)
   { errno = ENOTSUP; return -1; }
-SE_CONTEXT_INLINE int context_role_set (context_t sc _GL_UNUSED_PARAMETER,
-                                        char const *s _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE int
+context_role_set (_GL_ATTRIBUTE_MAYBE_UNUSED context_t sc,
+                  _GL_ATTRIBUTE_MAYBE_UNUSED char const *s)
   { errno = ENOTSUP; return -1; }
-SE_CONTEXT_INLINE int context_range_set (context_t sc _GL_UNUSED_PARAMETER,
-                                         char const *s _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE int
+context_range_set (_GL_ATTRIBUTE_MAYBE_UNUSED context_t sc,
+                   _GL_ATTRIBUTE_MAYBE_UNUSED char const *s)
   { errno = ENOTSUP; return -1; }
-SE_CONTEXT_INLINE int context_type_set (context_t sc _GL_UNUSED_PARAMETER,
-                                        char const *s _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE int
+context_type_set (_GL_ATTRIBUTE_MAYBE_UNUSED context_t sc,
+                  _GL_ATTRIBUTE_MAYBE_UNUSED char const *s)
   { errno = ENOTSUP; return -1; }
-SE_CONTEXT_INLINE char *context_type_get (context_t sc _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE char *
+context_type_get (_GL_ATTRIBUTE_MAYBE_UNUSED context_t sc)
   { errno = ENOTSUP; return (void *) 0; }
-SE_CONTEXT_INLINE char *context_range_get (context_t sc _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE char *
+context_range_get (_GL_ATTRIBUTE_MAYBE_UNUSED context_t sc)
   { errno = ENOTSUP; return (void *) 0; }
-SE_CONTEXT_INLINE char *context_role_get (context_t sc _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE char *
+context_role_get (_GL_ATTRIBUTE_MAYBE_UNUSED context_t sc)
   { errno = ENOTSUP; return (void *) 0; }
-SE_CONTEXT_INLINE char *context_user_get (context_t sc _GL_UNUSED_PARAMETER)
+SE_CONTEXT_INLINE char *
+context_user_get (_GL_ATTRIBUTE_MAYBE_UNUSED context_t sc)
   { errno = ENOTSUP; return (void *) 0; }
 
 _GL_INLINE_HEADER_END