[DX] Misleading error when the namespace of a controller is wrong

[javiereguiluz]

The problem

The other day I was playing with the Symfony Demo application, in which the routing is simply defined as:

# app/config/routing.yml
app:
    resource: @AppBundle/Controller/
    type:     annotation

I had a BlogController.php file with @Route() annotations in src/AppBundle/Controller/BlogController.php file.

Then, I moved this controller to the src/AppBundle/Controller/Admin/ folder without updating the namespace of the PHP class. Then, the application displayed the following error message:

FileLoaderImportCircularReferenceException in FileLoader.php line 97:
Circular reference detected in "/Users/javier/sf/symfony-demo/app/config/routing_dev.yml" 
("/Users/javier/sf/symfony-demo/app/config/routing_dev.yml" >
"/Users/javier/sf/symfony-demo/app/config/routing.yml" >
"/Users/javier/sf/symfony-demo/src/AppBundle/Controller/" >
"/Users/javier/sf/symfony-demo/app/config/routing_dev.yml").

Sadly this error message is very misleading because CircularReferenceException message looks scary and the error keeps talking about the routing_dev.yml file, which has nothing to do with the actual error.

The solution

Symfony already includes some great error messages when you are warned about typos and PHP classes mislocations. I'd like to see a better error message when the namespace of a controller file is not correct.

[stof]

why does AppBundle/Controller try to load routing_dev.yml again when the namespace is wrong ? this does not make any sense

[javiereguiluz]

@stof I know it's very strange. By the way, yesterday I was contacted by a Symfony developer which suffered the exact same problem and for the same reasons (moving a controller without updating its namespace).

[liutec]

Possibly a problem with re-throwing exceptions in FileLoader

My steps to reproduce are:

1. new symfony project (2.6.6 or 2.6.5) - no demo bundle, hard assets
2. edit app/config/routing.yml and change @AppBundle/Controller/ to @AppBundleX/Controller/
3. http://localhost/app_dev.php/app/example

I was unable to reproduce the problem following the steps above for Symfony 2.6.4

[liutec]

I've found this commit 0ebcf63 to have generated the problem.
Specifically throw $e; instead of just returning from src/Symfony/Component/HttpKernel/EventListener/ExceptionListener.php onKernelException when exception thrown during handler.

[nicolas-grekas]

Does #14192 enhance the situation? As stated in 0ebcf63#commitcomment-10558553, the issue is not in this commit, but in the error handling strategy of the route loader. A circular exception is just plain wrong.

[javiereguiluz]

@nicolas-grekas it's better ... but it's not good enough yet :)

After applying your changes, I see 4 exceptions now. However, I see first the "wrong exceptions". The best exception in this case would be the number 2 (and possibly the number 1 too):

[nicolas-grekas]

So, HttpKernel is at the maximum that is legitimate to do: error reporting does not hide anything so the situation can be handled by reading the page.
If we need more, then we need to rethink the error handling part of the route loader.

[liutec]

#14192 does the trick and saves a lot of debugging. Thx nicholas.

[stof]

@nicolas-grekas the first exception in this case is wrong: the exception happened too early in the Symfony lifecycle to even give a chance to the kernel to throw the kernel.exception event