--- src/system.c.orig	2008-11-26 18:53:51.000000000 +0900
+++ src/system.c	2021-12-25 20:30:44.000000000 +0900
@@ -52,6 +52,10 @@
 #include    "dir.h"
 #endif
 
+#if defined(__clang__)
+ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize);
+#endif
+
 #include    "sys/types.h"
 #include    "sys/stat.h"                        /* For stat()       */
 #if     ! defined( S_ISREG)
@@ -1276,7 +1280,7 @@
     chk_opts( sflag, trad);
 
     if (warn_level == -1)               /* No -W option             */
-        warn_level = 1;                 /* Default warning level    */
+        warn_level = 0;                 /* Default warning level    */
     else if (warn_level == 0xFF)
         warn_level = 0;                 /* -W0 has high precedence  */