Hi!

Currently, in order to collect an application's deprecations, we need to run the tests, and only the deprecations triggered by code used by those tests will be displayed after the test run.

However, many deprecations are static (e.g. those triggered by DebugClassLoader), and I believe we can find a way to display all of them without requiring full test coverage.

What do you think about introducing a new command, something like lint:deprecations, which would trigger the autoloading of all classes defined in the application? We could leverage the PSR-0 and PSR-4 autoload definitions from composer.json and autodiscover all classes under those namespaces using a RecursiveDirectoryIterator.

Of course, this wouldn't catch runtime deprecations, but it would still uncover many issues, even in applications without full test coverage. Combined with bin/console debug:container --deprecations, this could greatly help for Symfony upgrades for instance.

I also believe that handling a baseline for this would be useful. Maybe it could borrow some code from the PHPUnit bridge?