Summary

In a DEBUG compiler, I see an assertion failure in substitution while abusing GHC.

Steps to reproduce

Compile this on a DEBUG compiler:

data Q :: forall d. Type

data HR :: (forall d. Type) -> Type

x :: HR Q
x = undefined

Expected behavior

Type error: the inferred kind of HR quantifies the kind of d outside the higher-rank argument.

Environment

• GHC version used: HEAD