/* A compiler attribute is available in gcc versions 4.3.0 and later. */
# define _GL_WARN_ON_USE(function, message) \
extern __typeof__ (function) function __attribute__ ((__warning__ (message)))
-
+# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
+/* Verify the existence of the function. */
+# define _GL_WARN_ON_USE(function, message) \
+extern __typeof__ (function) function
# else /* Unsupported. */
# define _GL_WARN_ON_USE(function, message) \
-extern int _gl_warn_on_use
+_GL_WARN_EXTERN_C int _gl_warn_on_use
# endif
#endif
# define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
extern rettype function parameters_and_attributes \
__attribute__ ((__warning__ (msg)))
+# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
+/* Verify the existence of the function. */
+# define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
+extern rettype function parameters_and_attributes
# else /* Unsupported. */
# define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
-extern int _gl_warn_on_use
+_GL_WARN_EXTERN_C int _gl_warn_on_use
+# endif
+#endif
+
+/* _GL_WARN_EXTERN_C declaration;
+ performs the declaration with C linkage. */
+#ifndef _GL_WARN_EXTERN_C
+# if defined __cplusplus
+# define _GL_WARN_EXTERN_C extern "C"
+# else
+# define _GL_WARN_EXTERN_C extern
# endif
#endif