[perl #79178] STORE/FETCH of tie()d hash get stringified key

This bug has been present in non-threaded builds for a long time.
Change 38bb37b9aa introduced it to threaded builds.

$hash{...} makes its operand a shared-PV scalar if it is an OP_CONST.
But \"foo" is also an OP_CONST, as is anything generated with use
constant. This is the sort of thing that results:

$ perl5.8.5 -MO=Concise -e '$a{\"foo"}'
7  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
6     <2> helem vK/2 ->7
4        <1> rv2hv sKR/1 ->5
3           <$> gv(*a) s ->4
5        <$> const(PVIV "SCALAR(0x81b378)") s ->6
-e syntax OK

(My 5.8.5 installation is non-threaded.)

See the "SCALAR(0x81b378)" in there?

So this commit skips that optimisation if the key is ROK or if it is a
PVMG or higher.

1 files changed, 2 insertions, 1 deletions

diff --git a/op.c b/op.c
index 53641c7a8d..4c3c876662 100644
--- a/op.c
+++ b/op.c
@@ -9661,7 +9661,8 @@ Perl_rpeep(pTHX_ register OP *o)
 
 	    /* Make the CONST have a shared SV */
 	    svp = cSVOPx_svp(((BINOP*)o)->op_last);
-	    if (!SvFAKE(sv = *svp) || !SvREADONLY(sv)) {
+	    if ((!SvFAKE(sv = *svp) || !SvREADONLY(sv))
+	     && SvTYPE(sv) < SVt_PVMG && !SvROK(sv)) {
 		key = SvPV_const(sv, keylen);
 		lexname = newSVpvn_share(key,
 					 SvUTF8(sv) ? -(I32)keylen : (I32)keylen,