@_ can't have junk in it even in the non-USE_ITHREADS case because

caller() wants to populate @DB::args with it (causes a coredump
in Carp::confess())

p4raw-id: //depot/perl@6214

2 files changed, 18 insertions, 7 deletions

diff --git a/cop.h b/cop.h
index d6fdd23ab2..adf3863d03 100644
--- a/cop.h
+++ b/cop.h
@@ -106,13 +106,9 @@ struct block_sub {
     } STMT_END
 #endif /* USE_THREADS */
 
-#ifdef USE_ITHREADS
-   /* junk in @_ spells trouble when cloning CVs, so don't leave any */
-#  define CLEAR_ARGARRAY()	av_clear(cx->blk_sub.argarray)
-#else
-#  define CLEAR_ARGARRAY()	NOOP
-#endif /* USE_ITHREADS */
-
+/* junk in @_ spells trouble when cloning CVs and in pp_caller(), so don't
+ * leave any */
+#define CLEAR_ARGARRAY()	av_clear(cx->blk_sub.argarray)
 
 #define POPSUB(cx,sv)							\
     STMT_START {							\
diff --git a/t/op/runlevel.t b/t/op/runlevel.t
index e988ad9362..3865e52070 100755
--- a/t/op/runlevel.t
+++ b/t/op/runlevel.t
@@ -349,3 +349,18 @@ A 1
 bar
 B 2
 bar
+########
+sub n { 0 }
+sub f { my $x = shift; d(); }
+f(n());
+f();
+
+sub d {
+    my $i = 0; my @a;
+    while (do { { package DB; @a = caller($i++) } } ) {
+        @a = @DB::args;
+        for (@a) { print "$_\n"; $_ = '' }
+    }
+}
+EXPECT
+0