3 files changed, 8 insertions, 0 deletions

diff --git a/include/fortify-headers.h b/include/fortify-headers.h
index 67c4792..1581076 100644
--- a/include/fortify-headers.h
+++ b/include/fortify-headers.h
@@ -73,6 +73,12 @@
 #define __format(...)
 #endif
 
+#if __has_attribute (__diagnose_if)
+#define __warning_if(cond, msg) __attribute__ ((__diagnose_if (cond, msg, "warning")))
+#else
+#define __warning_if(cond, msg)
+#endif
+
 #endif
 
 #endif
diff --git a/include/stdlib.h b/include/stdlib.h
index 38015d4..aeed102 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -39,6 +39,7 @@ extern "C" {
 /* FIXME clang */
 #if (defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)) && !defined(__clang__)
 #undef realpath
+__warning_if(__p == NULL, "'realpath' called with path set to `NULL`; did you invert the arguments?")
 _FORTIFY_FN(realpath) char *realpath(const char *__p, char *__r)
 {
 #ifndef PATH_MAX
diff --git a/include/string.h b/include/string.h
index cf0be60..987b50c 100644
--- a/include/string.h
+++ b/include/string.h
@@ -71,6 +71,7 @@ _FORTIFY_FN(memmove) void *memmove(void * _FORTIFY_POS0 __d,
 }
 
 __access(write_only, 1, 3)
+__warning_if(__c != 0 && __n == 0, "'memset' will set `0` bytes; did you invert the arguments?")
 _FORTIFY_FN(memset) void *memset(void * _FORTIFY_POS0 __d, int __c, size_t __n)
 {
         size_t __b = __bos(__d, 0);