Non-covariant method doesn't trigger an error when return type declaration is missing

[johnbillion]

Bug report

When a method's return type is covariant with its grandparent class but not its parent class, PHPStan doesn't detect this problem even though it triggers a fatal error in PHP at runtime.

Code snippet that reproduces the problem

• https://phpstan.org/r/80daaeb5-855e-40bf-9b03-c3238b96e6f2
• https://3v4l.org/iVFd1

Expected output

I expect this to trigger an error

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[phpstan-bot]

@johnbillion After the latest push in 1.11.x, PHPStan now reports different result with your code snippet:

@@ @@
-No errors
+PHP 7.4 – 8.2 (1 error)
+==========
+
+19: Return type mixed of method three::foo() is not covariant with return type array of method two::foo().
+
+PHP 7.1 – 7.3 (1 error)
+==========
+
+19: Return type mixed of method three::foo() is not compatible with return type array of method two::foo().

Full report

PHP 7.4 – 8.2 (1 error)

Line	Error
19	Return type mixed of method three::foo() is not covariant with return type array of method two::foo().

PHP 7.1 – 7.3 (1 error)

Line	Error
19	Return type mixed of method three::foo() is not compatible with return type array of method two::foo().

[github-actions]

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