Fix bug #23141 : localization of readonly magic scalars

now produces an error "Modification of a read-only value
attempted", instead of silently failing.

p4raw-id: //depot/perl@20479

2 files changed, 16 insertions, 2 deletions

diff --git a/scope.c b/scope.c
index f738b5b68c..673a312900 100644
--- a/scope.c
+++ b/scope.c
@@ -214,7 +214,7 @@ S_save_scalar_at(pTHX_ SV **sptr)
 	    PL_tainted = oldtainted;
 	}
 	SvMAGIC(sv) = SvMAGIC(osv);
-	SvFLAGS(sv) |= SvMAGICAL(osv);
+	SvFLAGS(sv) |= SvMAGICAL(osv) | SvREADONLY(osv);
 	/* XXX SvMAGIC() is *shared* between osv and sv.  This can
 	 * lead to coredumps when both SVs are destroyed without one
 	 * of their SvMAGIC() slots being NULLed. */
diff --git a/t/op/local.t b/t/op/local.t
index 1bb8b8ac1b..5a5b7ee552 100755
--- a/t/op/local.t
+++ b/t/op/local.t
@@ -1,6 +1,6 @@
 #!./perl
 
-print "1..75\n";
+print "1..78\n";
 
 sub foo {
     local($a, $b) = @_;
@@ -257,3 +257,17 @@ print "not " if exists $h{'y'}; print "ok 72\n";
 print "not " if exists $h{'z'}; print "ok 73\n";
 print "not " if exists $ENV{_A_}; print "ok 74\n";
 print "not " if exists $ENV{_B_}; print "ok 75\n";
+
+# local() and readonly magic variables
+
+eval { local $1 = 1 };
+print "not " if $@ !~ /Modification of a read-only value attempted/;
+print "ok 76\n";
+
+eval { for ($1) { local $_ = 1 } };
+print "not " if $@ !~ /Modification of a read-only value attempted/;
+print "ok 77\n";
+
+eval { for ($1) { local $_ = 1 } };
+print "not " if $@;
+print "ok 78\n";