False-positive result on add nullable type in final method of abstract class

[vjik]

Example:

abstract class X {
	final public function test(string $var): self
}

changed to:

abstract class X {
	final public function test(?string $var): self
}

result will be:

[BC] CHANGED: The parameter $var of X#test() changed from string to ?string

Real example: yiisoft/html#78

[Ocramius]

So, if I understand correctly, if a method is final, then a contravariant type (expansion) is acceptable here.

The check should be this one:

BackwardCompatibilityCheck/src/DetectChanges/BCBreak/FunctionBased/ParameterTypeChanged.php

Line 22 in 7f185e3

final class ParameterTypeChanged implements FunctionBased

I think we need to restrict ParameterTypeChanged checks (see https://github.com/Roave/BackwardCompatibilityCheck/blob/7f185e3128276bbaa3d6c086ebee45e3ba02c374/bin/roave-backward-compatibility-check.php) to only non-contravariant, when the method is final.

[Ocramius]

Not going to be able to drag this into 6.0 - removing milestone for now.