Make utf8::encode respect magic

It has always ignored set-magic, as far as I can tell.

Since the magic flags patch (4bac9ae47b), it has been ignor-
ing get- magic on magical scalars that were already PVs.
sv_utf8_upgrade_flags_grow begins with an if(!SvPOK(sv)) check, which
used to mean ‘if this scalar is magic or not a string’, but now means
simply ‘if this scalar is not a string’.  SvPOK_nog is the new SvPOK.

Due to the way the flags now work, I had to modify sv_pvutf8n_force
as well, to keep existing tests passing.

1 files changed, 10 insertions, 1 deletions

diff --git a/t/op/utf8magic.t b/t/op/utf8magic.t
index 3d942c0cea..cc6936f392 100644
--- a/t/op/utf8magic.t
+++ b/t/op/utf8magic.t
@@ -6,7 +6,7 @@ BEGIN {
     require './test.pl';
 }
 
-plan tests => 4;
+plan tests => 5;
 
 use strict;
 
@@ -23,3 +23,12 @@ $str =~ /(.)/;
 ok !utf8::is_utf8($1), "is_utf8(bytes)";
 scalar "$1"; # invoke SvGETMAGIC
 ok !utf8::is_utf8($1), "is_utf8(bytes)";
+
+sub TIESCALAR { bless [pop] }
+sub FETCH     { $_[0][0] }
+sub STORE     { $::stored = pop }
+
+tie my $str2, "", "a";
+$str2 = "b";
+utf8::encode $str2;
+is $::stored, "a", 'utf8::encode respects get-magic on POK scalars';