PHP loader: use phpstan includes

[gharlan]

Using phpstan includes instead of require improves the cache handling.

At the moment phpstan does not recognize changes in the baseline files (e.g. when removing/comment a baseline entry manually). It only recognizes changes to the loader file.

[janedbal]

Thank you!

I also added a test that ensures it truely works in #36

[janedbal]

Released in 2.1.4

[clxmstaab]

nice!

[bendavies]

i'm unsure it it's related to this change or not, but now if I run phpstan in a PR, with baseline errors fixed, I am getting an error for each error that I've removed from the baseline.

Ignored error pattern ... was not matched in reported errors.                                                                                         

i am running it as suggested in the docs with actions/cache

https://github.com/phpstan/phpstan/blob/2.1.x/website/src/user-guide/result-cache.md?plain=1

[bendavies]

that said i've only just starting using this library. so another option is that this PR does not work as intended.

[clxmstaab]

if you don't want this errors you should use reportUnmatchedIgnoredErrors: false

https://phpstan.org/user-guide/ignoring-errors#reporting-unused-ignores

[bendavies]

no, the errors have been fixed and removed from the baseline, but phpstan thinks they are in the baseline. so I think this is a cache problem.

[bendavies]

I've cleared the github actions caches and it's resolved. so i'll see how it goes

[bendavies]

unfortunately this issue has reoccurred, every time baseline errors are removed.
I'll try setup a reproducer

[bendavies]

ignore all this. i worked out the problem. PEBCAK