Why is migration adapter nullable?

[martenb]

I found this commit, where many methods changed their return type to nullable. f385bbb

For example AbstractMigration::getAdapter() returns null or AdapterInterface.
Is that even possible, that migration does not have adapter?

With static analysis (like phpstan) i must check everytime, that adapeter is not null...

assert($this->getAdapter() !== null);
$this->getAdapter()->...

[dereuromark]

This most likely is due to legacy code expectations and can be fixed in a new major (1.0).

[MasterOdin]

It's only really possible that getAdapter() returns null within the constructor as we don't pass in the adapter there. However, before we call the change, up, or down methods, we do setAdapter on the migration (and seed) so at that point, yeah, getAdapter() should always return something.

I think modifying the getAdapter() method to throw an exception if it's null should be fine to put in a minor release as while it's a "breaking change", the people it gets broken for would be those that are doing ->getAdapter() in a custom adapter, and then having it always return null which seems so unlikely to probably not matter.