argp: Do not override GCC keywords with macros [BZ #16907]

glibc provides fallback definitions already.  It is not necessary to
suppress warnings for unknown attributes because GCC does this
automatically for system headers.

This commit does not sync with gnulib because gnulib has started to use
_GL_* macros in the header file, which are arguably in the gnulib
implementation space and not suitable for an installed glibc header
file.

(cherry picked from commit 2c820533c61fed175390bc6058afbbe42d2edc37)

3 files changed, 14 insertions, 55 deletions

diff --git a/ChangeLog b/ChangeLog
index bbc56c0aef..de82f344a1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2016-08-18  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #16907]
+	* argp/argp.h: Switch to __BEGIN_DECLS and __END_DECLS.
+	(__THROW, __NTH, __attribute__, __restrict): Remove definitions.
+	* argp/argp-fmtstream.h: Add __BEGIN_DECLS and __END_DECLS.
+	(__attribute__): Remove definition.
+
 2016-06-11  Florian Weimer  <fweimer@redhat.com>
 
 	[BZ #20222]
diff --git a/argp/argp-fmtstream.h b/argp/argp-fmtstream.h
index bdeaa54dc2..e8c5797f38 100644
--- a/argp/argp-fmtstream.h
+++ b/argp/argp-fmtstream.h
@@ -29,21 +29,6 @@
 #include <string.h>
 #include <unistd.h>
 
-#ifndef __attribute__
-/* This feature is available in gcc versions 2.5 and later.  */
-# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5) || \
-  defined __STRICT_ANSI__
-#  define __attribute__(Spec) /* empty */
-# endif
-/* The __-protected variants of `format' and `printf' attributes
-   are accepted by gcc versions 2.6.4 (effectively 2.7) and later.  */
-# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7) || \
-  defined __STRICT_ANSI__
-#  define __format__ format
-#  define __printf__ printf
-# endif
-#endif
-
 #if defined (__GNU_LIBRARY__) && defined (HAVE_LINEWRAP_H)
 /* line_wrap_stream is available, so use that.  */
 #define ARGP_FMTSTREAM_USE_LINEWRAP
@@ -111,6 +96,8 @@ struct argp_fmtstream
 
 typedef struct argp_fmtstream *argp_fmtstream_t;
 
+__BEGIN_DECLS
+
 /* Return an argp_fmtstream that outputs to STREAM, and which prefixes lines
    written on it with LMARGIN spaces and limits them to RMARGIN columns
    total.  If WMARGIN >= 0, words that extend past RMARGIN are wrapped by
@@ -297,6 +284,8 @@ __argp_fmtstream_point (argp_fmtstream_t __fs)
 
 #endif /* __OPTIMIZE__ */
 
+__END_DECLS
+
 #endif /* ARGP_FMTSTREAM_USE_LINEWRAP */
 
 #endif /* argp-fmtstream.h */
diff --git a/argp/argp.h b/argp/argp.h
index e67bbef739..7cb5a69f08 100644
--- a/argp/argp.h
+++ b/argp/argp.h
@@ -28,48 +28,12 @@
 #define __need_error_t
 #include <errno.h>
 
-#ifndef __THROW
-# define __THROW
-#endif
-#ifndef __NTH
-# define __NTH(fct) fct __THROW
-#endif
-
-#ifndef __attribute__
-/* This feature is available in gcc versions 2.5 and later.  */
-# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5) || \
-  defined __STRICT_ANSI__
-#  define __attribute__(Spec) /* empty */
-# endif
-/* The __-protected variants of `format' and `printf' attributes
-   are accepted by gcc versions 2.6.4 (effectively 2.7) and later.  */
-# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7) || \
-  defined __STRICT_ANSI__
-#  define __format__ format
-#  define __printf__ printf
-# endif
-#endif
-
-/* GCC 2.95 and later have "__restrict"; C99 compilers have
-   "restrict", and "configure" may have defined "restrict".  */
-#ifndef __restrict
-# if ! (2 < __GNUC__ || (2 == __GNUC__ && 95 <= __GNUC_MINOR__))
-#  if defined restrict || 199901L <= __STDC_VERSION__
-#   define __restrict restrict
-#  else
-#   define __restrict
-#  endif
-# endif
-#endif
-
 #ifndef __error_t_defined
 typedef int error_t;
 # define __error_t_defined
 #endif
 
-#ifdef  __cplusplus
-extern "C" {
-#endif
+__BEGIN_DECLS
 
 /* A description of a particular option.  A pointer to an array of
    these is passed in the OPTIONS field of an argp structure.  Each option
@@ -590,8 +554,6 @@ __NTH (__option_is_end (const struct argp_option *__opt))
 # endif
 #endif /* Use extern inlines.  */
 
-#ifdef  __cplusplus
-}
-#endif
+__END_DECLS
 
 #endif /* argp.h */