Description:
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Affected PHP versions: 7.0.0 - 7.1.0beta3

When implementing interfaces, it is impossible to override return types declarations with their (return types) subtypes/implementations although it is perfectly fine with LSP.

Test script:
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https://3v4l.org/MgU9b

Now I get error: "Fatal error: Declaration of CustomerFactory::create(): Customer must be compatible with AggregateRootFactory::create(): AggregateRoot in /file/path on line 15"

I expect: Customer type is implementation of AggregateRoot and it should work perfectly fine.