macros.h 2.4 KB
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/*
 * Portability macros used in include files.
 *
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 * The canonical version of this file is maintained in the rra-c-util package,
 * which can be found at <http://www.eyrie.org/~eagle/software/rra-c-util/>.
 *
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 * Written by Russ Allbery <eagle@eyrie.org>
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 *
 * The authors hereby relinquish any claim to any copyright that they may have
 * in this work, whether granted under contract or by operation of law or
 * international treaty, and hereby commit to the public, at large, that they
 * shall not, at any time in the future, seek to enforce any copyright in this
 * work against any person or entity, or prevent any person or entity from
 * copying, publishing, distributing or creating derivative works of this
 * work.
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 */

#ifndef PORTABLE_MACROS_H
#define PORTABLE_MACROS_H 1

/*
 * __attribute__ is available in gcc 2.5 and later, but only with gcc 2.7
 * could you use the __format__ form of the attributes, which is what we use
 * (to avoid confusion with other macros).
 */
#ifndef __attribute__
# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
#  define __attribute__(spec)   /* empty */
# endif
#endif

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/*
 * We use __alloc_size__, but it was only available in fairly recent versions
 * of GCC.  Suppress warnings about the unknown attribute if GCC is too old.
 * We know that we're GCC at this point, so we can use the GCC variadic macro
 * extension, which will still work with versions of GCC too old to have C99
 * variadic macro support.
 */
#if !defined(__attribute__) && !defined(__alloc_size__)
# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 3)
#  define __alloc_size__(spec, args...) /* empty */
# endif
#endif

/*
 * LLVM and Clang pretend to be GCC but don't support all of the __attribute__
 * settings that GCC does.  For them, suppress warnings about unknown
 * attributes on declarations.  This unfortunately will affect the entire
 * compilation context, but there's no push and pop available.
 */
#if !defined(__attribute__) && (defined(__llvm__) || defined(__clang__))
# pragma GCC diagnostic ignored "-Wattributes"
#endif

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/*
 * BEGIN_DECLS is used at the beginning of declarations so that C++
 * compilers don't mangle their names.  END_DECLS is used at the end.
 */
#undef BEGIN_DECLS
#undef END_DECLS
#ifdef __cplusplus
# define BEGIN_DECLS    extern "C" {
# define END_DECLS      }
#else
# define BEGIN_DECLS    /* empty */
# define END_DECLS      /* empty */
#endif

#endif /* !PORTABLE_MACROS_H */