link-warning.h

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00001 /* GL_LINK_WARNING("literal string") arranges to emit the literal string as
00002    a linker warning on most glibc systems.
00003    We use a linker warning rather than a preprocessor warning, because
00004    #warning cannot be used inside macros.  */
00005 #ifndef GL_LINK_WARNING
00006   /* This works on platforms with GNU ld and ELF object format.
00007      Testing __GLIBC__ is sufficient for asserting that GNU ld is in use.
00008      Testing __ELF__ guarantees the ELF object format.
00009      Testing __GNUC__ is necessary for the compound expression syntax.  */
00010 # if defined __GLIBC__ && defined __ELF__ && defined __GNUC__
00011 #  define GL_LINK_WARNING(message) \
00012      GL_LINK_WARNING1 (__FILE__, __LINE__, message)
00013 #  define GL_LINK_WARNING1(file, line, message) \
00014      GL_LINK_WARNING2 (file, line, message)  /* macroexpand file and line */
00015 #  define GL_LINK_WARNING2(file, line, message) \
00016      GL_LINK_WARNING3 (file ":" #line ": warning: " message)
00017 #  define GL_LINK_WARNING3(message) \
00018      ({ static const char warning[sizeof (message)]             \
00019           __attribute__ ((__unused__,                           \
00020                           __section__ (".gnu.warning"),         \
00021                           __aligned__ (1)))                     \
00022           = message "\n";                                       \
00023         (void)0;                                                \
00024      })
00025 # else
00026 #  define GL_LINK_WARNING(message) ((void) 0)
00027 # endif
00028 #endif