Add option to log deprecation errors to prepare for Drupal 9

Seems like a new title is in order.

What about using PHP settings to make the behavior configurable? We could make this opt-in by assuming a FALSE default and punt aggregation/filtering to a follow-up issue :)

I closed 📌 Allow to display/log E_USER_DEPRECATED messages Closed: duplicate as a duplicate. Note that the other issue also tried to handle skipped deprecations, which is IMHO crucial for this, as some of them have been logged a _lot_ historically and would completely spam that log, making it rather useless.

Removed redundant tag

@Berdir

Note that the other issue also tried to handle skipped deprecations, which is IMHO crucial for this, as some of them have been logged a _lot_ historically and would completely spam that log, making it rather useless.

Fair, what about making those configurable via a setting as well? We could hardcode a default if the setting is NULL.

Here's some initial work on this: https://git.drupalcode.org/issue/drupal-3024296/-/compare/11.x...3024296...
Not sure if filename - based deprecation level (all, contrib + custom, custom only) filtering is reliable enough, namespace is not for sure as we cannot distinguish contrib from custom at all there. Let's get this moving in any case :)

Created a MR against 11.x, no tests yet as it'll be nice to receive feedback first and some recommendations what'd be the best way to test (Unit?).
Marking for initial review.
Adding a patch to lock at this state as well to avoid composer issues if the MR gets updated as well.

MR appears to have some failures.

@smutsgrave, yes, I'm aware of that - typo in a comment. Nevertheless, I asked for a small review at this stage to ensure the direction is correct before more hours are spent on this. Can we have it?

Go for it. Haven't checked the follow up tag need either.

Thanks, received some internal feedback on this and thought about it a bit in the meantime.
TODO:
- fix typo obviously
- remove deprecation level in favor or a boolean switch and ignored file path patterns (*/core/* and */vendor/* by default)
- we should probably only log deprecations instead of displaying them on pages.

Right, now work has to be done to update existing tests and write new ones. Moving this to review again so we can see if this has chances of merging at this state assuming tests are handled.

Seems @alexpott left some feedback on the MR.

@alexpott and I have looked at this, removing the tag

Started a test but in the test there is no logging of the deprecation message. I don't see why that is. Anyone?

it may help to catch deprecations from upcoming PHP release 🌱 [META] Make Drupal 10.3/11 compatible with PHP 8.4 Active

Resolved the threads but the kernel failure seems related to the change

Drupal\Core\Config\Schema\SchemaIncompleteException: Schema errors for system.logging with the following errors: 0 [] 'log_deprecations' is a required key., 1 [] 'deprecations_ignored_file_patterns' is a required key., 2 [] 'ignored_deprecations' is a required key.

Rebase and fixed the failing kernel test.

Believe all feedback has been addressed on this one, do we still need a follow up?