isUTF8_CHAR() Check ptr before dereferencing

It is legal to call this function, though not so done in core, with
empty input.  By swapping two conditions in the same 'if', we check if
empty before trying to access it.

1 files changed, 1 insertions, 1 deletions

diff --git a/inline.h b/inline.h
index bbf27da6f5..8ec66b2290 100644
--- a/inline.h
+++ b/inline.h
@@ -1140,7 +1140,7 @@ Perl_isUTF8_CHAR(const U8 * const s0, const U8 * const e)
 
 #if defined(UV_IS_QUAD) || defined(EBCDIC)
 
-    if (NATIVE_UTF8_TO_I8(*s0) == 0xFF && e - s0 >= UTF8_MAXBYTES) {
+    if (e - s0 >= UTF8_MAXBYTES && NATIVE_UTF8_TO_I8(*s0) == 0xFF) {
        return is_utf8_char_helper(s0, e, 0);
     }