Am 09.08.2017 um 12:20 schrieb Johannes Loher:

On Wed, 9 Aug 2017 11:38:24 +0200, Sönke Ludwig wrote:

[...]

Since redirection is implemented as returning a particular status code,
it cannot be mixed with other kinds of replies (i.e. the forbidden
response that would otherwise be generated by the thrown exception. If
both is required, you'll have to perform the redirection by setting the
Refresh header of the response object instead (with the appropriate
refresh timeout).

Otherwise, you could pass any error message using a query parameter in
the call to redirect() and then simply return AuthInfo.init;. The
forbidden code would not be reported, but the destination page could
still display the message then.

Thanks for your Answer. I have a few more questions:

I tried your first suggestion, and it works as expected for me. However, of course this displays the 403 error page (blank page showing Error 403 and the Exception message) before the Refresh timeout runs out. For normal requests, It is possible to set the errorpage with @errorDisplay. Is there any possibility to do this in this case, too?

Not using an annotation, but you can just render pages from within the
authenticate method, or call other functions of the class to do so.
Setting res.statusCode to forbidden before rendering should also
work as expected.

The second approach also works as expected. But still, the question remains, if it is safe to mark the call to redirect @trusted.

Sorry, I forgot about the trusted issue while replying. I've opened a PR
to mark all those functions as @safe. The only @trusted that is
required is for accessing a TaskLocal when the vibe-core package isn't
used and that also generally has a memory safe API.

https://github.com/rejectedsoftware/vibe.d/pull/1886