• Ningning Xie's avatar
    Fix `:k` command: add validity checking · c4a876d5
    Ningning Xie authored
    This patch fixes #15806, where we found that the `:k` command in GHCi
    misses a validity checking for the type.
    Missing validity checking causes `:k` to accept types that are not validated.
    For example, `:k (Maybe (forall a. a -> a))` (incorrectly) returns `*`, while
    impredictivity of type instantiation shouldn't be allowed.
    Test Plan: ./validate
    Reviewers: simonpj, goldfire, bgamari
    Reviewed By: bgamari
    Subscribers: rwbarton, carter
    GHC Trac Issues: #15806
    Differential Revision: https://phabricator.haskell.org/D5265
TcRnDriver.hs 119 KB