RT #4682: given() didn't scope $_ correctly

given(expr) {...} behaves similarly to { my $_ = expr; ...},
except that, prior to this commit, it wasn't doing the SAVECLEARSV()
that pp_padsv would do.  This meant that $_ was still marked as stale
while in scope, and wasn't getting cleared at the end of scope.

1 files changed, 1 insertions, 0 deletions

diff --git a/pp_ctl.c b/pp_ctl.c
index 0d2aae1639..238f230116 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -4367,6 +4367,7 @@ PP(pp_entergiven)
     ENTER_with_name("given");
     SAVETMPS;
 
+    SAVECLEARSV(PAD_SVl(PL_op->op_targ));
     sv_setsv_mg(PAD_SV(PL_op->op_targ), POPs);
 
     PUSHBLOCK(cx, CXt_GIVEN, SP);