[perl #78194] Make list slices copy PADTMPs in lv cx

So that slices that reference the same value multiple times (such as
(...)[1,1]) will exhibit referential identity (\(...)[1,1] will return
two references to the same scalar).

1 files changed, 3 insertions, 0 deletions

diff --git a/pp.c b/pp.c
index cadfe96371..99f7d1fa07 100644
--- a/pp.c
+++ b/pp.c
@@ -4773,6 +4773,7 @@ PP(pp_lslice)
     SV ** const firstlelem = PL_stack_base + POPMARK + 1;
     SV ** const firstrelem = lastlelem + 1;
     I32 is_something_there = FALSE;
+    const U8 mod = PL_op->op_flags & OPf_MOD;
 
     const I32 max = lastrelem - lastlelem;
     SV **lelem;
@@ -4804,6 +4805,8 @@ PP(pp_lslice)
 	    is_something_there = TRUE;
 	    if (!(*lelem = firstrelem[ix]))
 		*lelem = &PL_sv_undef;
+	    else if (mod && SvPADTMP(*lelem) && !IS_PADGV(*lelem))
+		*lelem = firstrelem[ix] = sv_mortalcopy(*lelem);
 	}
     }
     if (is_something_there)