use locale; fc(""); shouldn't taint.

fc() brought to life its own version of #39028. fc(""), like
lc("") and friends, shouldn't taint the result.

diff --git a/pp.c b/pp.c
index 29ed4c6..f6ad80f 100644 (file)
--- a/pp.c
+++ b/pp.c
@@ -4184,7 +4184,7 @@ PP(pp_fc)
            SvTAINTED_on(dest);
        }
     } /* Unflagged string */
-    else {
+    else if (len) {
         /* For locale, bytes, and nothing, the behavior is supposed to be the
          * same as lc().
          */