Deprecate traits ForwardCompatTestTrait

[jderusse]

Q	A
Branch?	4.3
Bug fix?	no
New feature?	no
BC breaks?	no
Deprecations?	yes
Tests pass?	yes
Fixed tickets	#32844
License	MIT
Doc PR	NA

As symfony 4.3 is compatible with php 7.1 which supports typehint, we don't have to provide a trait that provide 2 signatures in order to be compatible with both PHPUnit 8 and bellow

[nicolas-grekas]

They are internal and used by core, we cannot do this.

[derrabus]

Suggested change

	@trigger_error(sprintf('The "%s" trait is deprecated since Symfony 4.3, typehint methods "setUp" and "tearDown" with ": void" instead.', ForwardCompatTestTrait::class), E_USER_DEPRECATED);
	@trigger_error(sprintf('The "%s" trait is deprecated since Symfony 4.4, typehint methods "setUp" and "tearDown" with ": void" instead.', ForwardCompatTestTrait::class), E_USER_DEPRECATED);

[jderusse]

They are internal and used by core, we cannot do this.

@nicolas-grekas then we should stop using them. I don't see what problem they solve (when using php 7.1).

[nicolas-grekas]

I agree, that's what we should do.

[jderusse]

Closing as this trait is used by exposed abstract classes like KernelTestCase. Removing this trait means to add a : void return typehint on abstract class which is a BC break.