HTTPServerResponse.writeJsonBody causes assertion

[japplegame]

HTTPServerResponse.writeJsonBody causes assertion if compression used.

Test-case:

import vibe.d;

shared static this() {
    auto settings = new HTTPServerSettings;
    settings.port = 8080;
    settings.bindAddresses = ["127.0.0.1"];
    settings.useCompressionIfPossible = true; // compression used

    auto router = new URLRouter;
    router.get("/", (request, response) {
        struct Result {
            string data;
        }
        response.writeJsonBody(Result("test"));
    });

    listenHTTP(settings, router);
}

The reason is incompatibility between compression and non-chunked encoding.
writeJsonBody() adds Content-Length header (see code), but bodyWriter removes it because compression used (see code). Because of this, body writer uses ChunkedOutputStream instead CountingOutputStream, which leads to assertion at this line.

[s-ludwig]

Hmm, looks like the assertion has to go. There was actually an issue there (one of the output ranges missing a put(char) overload caused too many bytes to be written), so that's a bit unfortunate, but the only other way would be to install another counting wrapper stream and I'm not sure if adding more overhead just for an assertion is a good idea.