• eir@cis.upenn.edu's avatar
    Fix #10815 by kind-checking type patterns against known kinds. · 2d4db40a
    eir@cis.upenn.edu authored
    tcFamTyPats now must take information about the instantiation of any
    class variables, when checking the instance of an associated type.
    
    Getting this to work out required some unexpected refactoring in
    TcDeriv. TcDeriv needs to look at class instances because of the
    possibility of associated datatypes with `deriving` specs. TcDeriv
    worked over the user-specified instances. But any data family instances
    were already processed, and TcDeriv had no way of finding the rep
    tycons. Indeed, TcDeriv *re-type-checked* any data family instances
    in an attempt to rediscover what GHC already knew. So, this commit
    introduces better tracking of compiled data families between TcInstDcls
    and TcDeriv to streamline all of this.
    2d4db40a
TcTyClsDecls.hs 102 KB