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[libtasn1.git] / build-aux / link-warning.h
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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; \
25 # else
26 # define GL_LINK_WARNING(message) ((void) 0)
27 # endif
28 #endif