Regression: abstract entities in the middle of a hierarchy need to be part of discriminator map

[BenMorel]

BC Break Report

Q	A
BC Break	yes
Version	2.9.x, 2.10.x

Summary

As mentioned in #8771 (comment), there is a regression that affects both 2.9 and 2.10:

If an entity hierarchy has an abstract entity class in the middle of the hierarchy, Doctrine complains that it must be part of the discriminator map. Example:

• abstract class A
  • abstract class B
    • class C

bin/console doctrine:schema:validate reports:

[FAIL] The entity-class B mapping is invalid:

• Entity class 'B' is part of inheritance hierarchy, but is not mapped in the root entity 'A' discriminator map. All subclasses must be listed in the discriminator map.

This doesn't make sense, as there cannot be an entry in the database for an abstract entity class.

This was working fine up to Doctrine 2.8.

The quick fix for those affected is to add "fake" entries to the discriminator map for abstract child entities, that do not have an equivalent in the database ENUM; which is rather ugly.

[derrabus]

Do you want to work on a fix?

[BenMorel]

@derrabus Yes! I opened a PR in #9096, building on top of #8903.

I'm dubious as to whether it makes sense to have both ! $class->reflClass->isAbstract() and ! $class->isMappedSuperclass now though: does it make sense to have a non-abstract @MappedSuperclass? Isn't it enough to check if the class is abstract?

[derrabus]

Looks good to me. 🙂

[BenMorel]

Be careful that this has been reverted in #9262.

[mpdude]

#10420 suggests to fix this again; it should now be possible due to #10411.