Change save/restore behavior for comparisons

S_mergesortsv was saving the current comparison routine only when the
SORTf_DESC flag was set, but "restoring" it when ANY flag was set.
When some flag other than SORTf_DESC was set, this could lead to
the pointer to the comparison routine being set to NULL,
triggering a segfault when the routine was subsequently invoked.

1 files changed, 1 insertions, 1 deletions

diff --git a/pp_sort.c b/pp_sort.c
index 604950910a..9d31bdafe0 100644
--- a/pp_sort.c
+++ b/pp_sort.c
@@ -558,7 +558,7 @@ S_mergesortsv(pTHX_ gptr *base, size_t nmemb, SVCOMPARE_t cmp, U32 flags)
     }
   done:
     if (aux != small) Safefree(aux);	/* free iff allocated */
-    if (flags) {
+    if (savecmp != NULL) {
 	 PL_sort_RealCmp = savecmp;	/* Restore current comparison routine, if any */
     }
     return;