In newSVhek(), use sv_usepvn_flags() to avoid a malloc()/copy/free()

The return value of bytes_to_utf8() is a malloc()ed string, which we can donate
to the scalar to use as its buffer. Previously the code free()d this memory,
after using it as a parameter to newSVpvn(), which allocates a new buffer and
copies to it.

diff --git a/sv.c b/sv.c
index a1ca186..e811580 100644 (file)
--- a/sv.c
+++ b/sv.c
@@ -8214,11 +8214,11 @@ Perl_newSVhek(pTHX_ const HEK *const hek)
               Andreas would like keys he put in as utf8 to come back as utf8
            */
            STRLEN utf8_len = HEK_LEN(hek);
-           const U8 *as_utf8 = bytes_to_utf8 ((U8*)HEK_KEY(hek), &utf8_len);
-           SV * const sv = newSVpvn ((const char*)as_utf8, utf8_len);
-
+           SV * const sv = newSV_type(SVt_PV);
+           char *as_utf8 = (char *)bytes_to_utf8 ((U8*)HEK_KEY(hek), &utf8_len);
+           /* bytes_to_utf8() allocates a new string, which we can repurpose: */
+           sv_usepvn_flags(sv, as_utf8, utf8_len, SV_HAS_TRAILING_NUL);
            SvUTF8_on (sv);
-           Safefree (as_utf8); /* bytes_to_utf8() allocates a new string */
            return sv;
        } else if (flags & (HVhek_REHASH|HVhek_UNSHARED)) {
            /* We don't have a pointer to the hv, so we have to replicate the