Add a readonly check to Perl_sv_utf8_upgrade_flags, a regresion test

in utf8.t, and fix 3 bugs it exposed in utfhash.t

p4raw-id: //depot/perl@22463

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/utf8.t b/lib/utf8.t
index 33cd5966af..90035e56b3 100644
--- a/lib/utf8.t
+++ b/lib/utf8.t
@@ -37,7 +37,7 @@ no utf8; # Ironic, no?
 #
 #
 
-plan tests => 143;
+plan tests => 144;
 
 {
     # bug id 20001009.001
@@ -409,3 +409,9 @@ SKIP: {
     ok( utf8::is_utf8($b), " utf8::is_utf8 beyond"); # $b stays in UTF-8.
     ok( utf8::is_utf8($c), " utf8::is_utf8 unicode");
 }
+
+{
+    eval {utf8::encode("£")};
+    like($@, qr/^Modification of a read-only value attempted/,
+	 "utf8::encode should refuse to touch read-only values");
+}