[5.6] Fix relative route URL generation with custom host formatter

[staudenmeir]

Generating relative route URLs doesn't work with a custom host formatter:

$url = new UrlGenerator(
    $routes = new RouteCollection,
    $request = Request::create('http://www.foo.com/')
);

$routes->add(
    new Route(['GET'], '/named-route', ['as' => 'plain'])
);

$url->formatHostUsing(function ($host) {
    return str_replace('foo.com', 'foo.org', $host);
});

dd($url->route('plain', [], false));
// expected: '/named-route'
// actual: '/http://www.foo.org/named-route'

RouteUrlGenerator::to() tries to remove the original root, but fails because the root has been modified.

Fixes #24047.

[vlakoff]

That's an interesting regex… I tried this and it seems to work fine, but maybe there are some unit tests to add (for example, with a query string).

[staudenmeir]

There are a lot of tests in RoutingUrlGeneratorTest::testBasicRouteGeneration().

[vlakoff]

Sure thing, thanks for pointing these. Apparently what I had in mind is already covered.