1 /* GL_LINK_WARNING("literal string") arranges to emit the literal string as 2 a linker warning on most glibc systems. 3 We use a linker warning rather than a preprocessor warning, because 4 #warning cannot be used inside macros. */ 5 #ifndef GL_LINK_WARNING 6 /* This works on platforms with GNU ld and ELF object format. 7 Testing __GLIBC__ is sufficient for asserting that GNU ld is in use. 8 Testing __ELF__ guarantees the ELF object format. 9 Testing __GNUC__ is necessary for the compound expression syntax. */ 10 # if defined __GLIBC__ && defined __ELF__ && defined __GNUC__ 11 # define GL_LINK_WARNING(message) \ 12 GL_LINK_WARNING1 (__FILE__, __LINE__, message) 13 # define GL_LINK_WARNING1(file, line, message) \ 14 GL_LINK_WARNING2 (file, line, message) /* macroexpand file and line */ 15 # define GL_LINK_WARNING2(file, line, message) \ 16 GL_LINK_WARNING3 (file ":" #line ": warning: " message) 17 # define GL_LINK_WARNING3(message) \ 18 ({ static const char warning[sizeof (message)] \ 19 __attribute__ ((__unused__, \ 20 __section__ (".gnu.warning"), \ 21 __aligned__ (1))) \ 22 = message "\n"; \ 23 (void)0; \ 24 }) 25 # else 26 # define GL_LINK_WARNING(message) ((void) 0) 27 # endif 28 #endif 29