Read-only COWs should not be exempt from s/// croaking

$  ./miniperl -Ilib -e 'for(__PACKAGE__) { s/a/a/ }'
Modification of a read-only value attempted at -e line 1.
$  ./miniperl -Ilib -e 'for(__PACKAGE__) { s/b/b/ }'
$  ./miniperl -Ilib -e 'for("main") { s/a/a/ }'
Modification of a read-only value attempted at -e line 1.
$  ./miniperl -Ilib -e 'for("main") { s/b/b/ }'
Modification of a read-only value attempted at -e line 1.

When I pass the constant "main" to s///, it croaks whether the regular
expression matches or not.

When I pass __PACKAGE__, which has the same content and is also read-
only, it only croaks when the pattern matches.

This commit removes some logic that is left over from when
READONLY+FAKE meant copy-on-write.  Read-only does mean read-only now,
so copy-on-write scalars should not be exempt from read-only checks.

1 files changed, 0 insertions, 3 deletions

diff --git a/pp_hot.c b/pp_hot.c
index 5010606ee0..3adeb1e8f7 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -2058,9 +2058,6 @@ PP(pp_subst)
 	sv_force_normal_flags(TARG,0);
 #endif
     if (!(rpm->op_pmflags & PMf_NONDESTRUCT)
-#ifdef PERL_ANY_COW
-	&& !is_cow
-#endif
 	&& (SvREADONLY(TARG)
 	    || ( ((SvTYPE(TARG) == SVt_PVGV && isGV_with_GP(TARG))
 		  || SvTYPE(TARG) > SVt_PVLV)