/ phpstan-src Public
Fix invariance composition #2054
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Now for the more complicated bit.
In my research for type projections, I've found this paper very resourceful; in section 3.1 which discusses variance composition, it says that "invariance transforms everything into invariance".
So, as also argued in #1492 (comment), this is indeed technically a bugfix. To make sure that the position variance is composed correctly, I've also replicated the test case from this PR in Kotlin whose type system I firmly trust.
Let's see what builds this breaks :)