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-rw-r--r--build-aux/link-warning.h28
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diff --git a/build-aux/link-warning.h b/build-aux/link-warning.h
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+/* GL_LINK_WARNING("literal string") arranges to emit the literal string as
+ a linker warning on most glibc systems.
+ We use a linker warning rather than a preprocessor warning, because
+ #warning cannot be used inside macros. */
+#ifndef GL_LINK_WARNING
+ /* This works on platforms with GNU ld and ELF object format.
+ Testing __GLIBC__ is sufficient for asserting that GNU ld is in use.
+ Testing __ELF__ guarantees the ELF object format.
+ Testing __GNUC__ is necessary for the compound expression syntax. */
+# if defined __GLIBC__ && defined __ELF__ && defined __GNUC__
+# define GL_LINK_WARNING(message) \
+ GL_LINK_WARNING1 (__FILE__, __LINE__, message)
+# define GL_LINK_WARNING1(file, line, message) \
+ GL_LINK_WARNING2 (file, line, message) /* macroexpand file and line */
+# define GL_LINK_WARNING2(file, line, message) \
+ GL_LINK_WARNING3 (file ":" #line ": warning: " message)
+# define GL_LINK_WARNING3(message) \
+ ({ static const char warning[sizeof (message)] \
+ __attribute__ ((__unused__, \
+ __section__ (".gnu.warning"), \
+ __aligned__ (1))) \
+ = message "\n"; \
+ (void)0; \
+ })
+# else
+# define GL_LINK_WARNING(message) ((void) 0)
+# endif
+#endif