todo test for GH 5835 (local($^W) does not work correctly)

Author: 1-1sam

t/run/todo.t

@@ -100,6 +100,21 @@ my $is_debugging_build = $Config{cppflags} =~ /-DDEBUGGING/;
 
 our $TODO;
 
+TODO: {
+    local $::TODO = 'GH 5835';
+    my $results = fresh_perl(<<~'EOF', {});
+        $^W = 1;
+        print "$^W";
+        {
+            local $^W = $^W;
+            print "$^W";
+        }
+        print "$^W";
+        EOF
+    is($?, 0, 'perl exited normally');
+    is($results, '111', 'localized $^W behaves like ordinary localized scalar');
+}
+
 TODO: {
     local $::TODO = "GH 16008";
     my $results = fresh_perl(<<~'EOF', {} );