USE_ITHREADS tweak (reused pad values could be SvREADONLY if

they belonged to freed OP_CONSTs)

p4raw-id: //depot/perl@4761

diff --git a/op.c b/op.c
index 0351b0e..383e917 100644 (file)
--- a/op.c
+++ b/op.c
@@ -512,8 +512,12 @@ Perl_pad_free(pTHX_ PADOFFSET po)
     DEBUG_X(PerlIO_printf(Perl_debug_log, "Pad 0x%"UVxf" free %"IVdf"\n",
                          PTR2UV(PL_curpad), (IV)po));
 #endif /* USE_THREADS */
-    if (PL_curpad[po] && PL_curpad[po] != &PL_sv_undef)
+    if (PL_curpad[po] && PL_curpad[po] != &PL_sv_undef) {
        SvPADTMP_off(PL_curpad[po]);
+#ifdef USE_ITHREADS
+       SvREADONLY_off(PL_curpad[po]);  /* could be a freed constant */
+#endif
+    }
     if ((I32)po < PL_padix)
        PL_padix = po - 1;
 }