Initial implementation. Leak reporting output isn't very helpful just…

… yet.

lib/CatalystX/LeakChecker.pm

@@ -0,0 +1,48 @@
+package CatalystX::LeakChecker;
+
+use Moose::Role;
+use PadWalker 'closed_over';
+use Scalar::Util 'weaken', 'isweak';;
+use aliased 'Data::Visitor::Callback', 'Visitor';
+
+use namespace::autoclean -also => [qw/Visitor visit_code/];
+
+sub visit_code {
+    my ($self, $code, $weak_ctx, $leaks) = @_;
+    my $vars = closed_over $code;
+
+    while (my ($name, $val) = each %{ $vars }) {
+        next unless $weak_ctx == ${ $val };
+        next if isweak ${ $val };
+        push @{ $leaks }, $name;
+    }
+
+    return $code;
+}
+
+sub format_table {
+    my @leaks = @_;
+
+    my $t = Text::SimpleTable->new([ 70, 'Variable' ]);
+    $t->row($_) for @leaks;
+    return $t->draw;
+}
+
+after finalize => sub {
+    my ($ctx) = @_;
+    my @leaks;
+
+    my $weak_ctx = $ctx;
+    weaken $weak_ctx;
+
+    my $visitor = Visitor->new(
+        code => sub { visit_code(@_, $weak_ctx, \@leaks) },
+    );
+    $visitor->visit($ctx->stash);
+    return unless @leaks;
+
+    my $msg = "Leaked context:\n" . format_table(@leaks);
+    $ctx->log->debug($msg) if $ctx->debug;
+};
+
+1;