Forbid source filters in Unicode evals

Source filters have always been byte-level filters.  Therefore they
don’t make sense on Unicode strings, unless we are planning to add
new APIs to support it.  Until then, croak.

1 files changed, 10 insertions, 1 deletions

diff --git a/ext/XS-APItest/t/eval-filter.t b/ext/XS-APItest/t/eval-filter.t
index 8d370e59a7..d4a9153613 100644
--- a/ext/XS-APItest/t/eval-filter.t
+++ b/ext/XS-APItest/t/eval-filter.t
@@ -1,9 +1,18 @@
 #!perl -w
 use strict;
 
-use Test::More tests => 1;
+use Test::More tests => 3;
 use XS::APItest;
 
+{
+    use feature "unicode_eval";
+    my $unfiltered_foo = "foo";
+    eval "BEGIN { filter() }";
+    like $@, qr/^Source filters apply only to byte streams at /,
+	'filters die under unicode_eval';
+    is "foo", $unfiltered_foo, 'filters leak not out of unicode evals';
+}
+
 BEGIN { eval "BEGIN{ filter() }" }
 
 is "foo", "fee", "evals share filters with the currently compiling scope";