[perl #71076] sort with active sub (5.10 regression)

One of the tests in sort.t causes a bus error (or sometimes ‘Undefined
subroutine called’) if run multiple times. This is because sort
decreases the refcount of an active sub used as a comparison routine.

Ironically enough, this test was added by the very change that broke it
(25953/9850bf2).

1 files changed, 5 insertions, 0 deletions

diff --git a/pp_sort.c b/pp_sort.c
index a657fa744a..12e77f9445 100644
--- a/pp_sort.c
+++ b/pp_sort.c
@@ -1652,6 +1652,11 @@ PP(pp_sort)
 	    if (!(flags & OPf_SPECIAL)) {
 		cx->cx_type = CXt_SUB;
 		cx->blk_gimme = G_SCALAR;
+		/* If our comparison routine is already active (CvDEPTH is
+		 * is not 0),  then PUSHSUB does not increase the refcount,
+		 * so we have to do it ourselves, because the LEAVESUB fur-
+		 * ther down lowers it. */
+		if (CvDEPTH(cv)) SvREFCNT_inc_simple_void_NN(cv);
 		PUSHSUB(cx);
 		if (!is_xsub) {
 		    AV* const padlist = CvPADLIST(cv);