Type parameters usage at forbidden positions

[klimick]

Bug report

Phpstan allows to use type parameters where they cannot be used.

Code snippet that reproduces the problem

https://phpstan.org/r/8dc1c703-eb15-408a-a146-83c8ead2c840

Expected output

"covariant type A occurs in contravariant position"

Did PHPStan help you today? Did it make you happy in any way?

No response

[klimick]

Why it is bad at runtime: https://3v4l.org/A0joX

[klimick]

More complex example: https://phpstan.org/r/476e20b9-112d-49c4-a3a1-f86342e3598a
And full runtime example: https://3v4l.org/U1rIf

[ondrejmirtes]

/cc @jiripudil

[jiripudil]

Hm, looks like ClosureType uses NonGenericTypeTrait, and thus does not report referenced template types at all. Perhaps it should implement inferTemplateTypes and getReferencedTemplateTypes the same way that CallableType does?

[ondrejmirtes]

Closures cannot be generic, not until #8964 is implemented. But yeah, it should still implement inferTemplateTypes and getReferencedTemplateTypes because that's totally relevant even today.