• niteria's avatar
    Build the substitution correctly in piResultTy · dbf72dbc
    niteria authored
    This fixes a bug where piResultTy created
    substitutions that would violate both of the invariants
    in Note [The substitution invariant].
    Test Plan: ./validate --slow
    Reviewers: goldfire, simonpj, austin, bgamari
    Reviewed By: simonpj, bgamari
    Subscribers: simonmar, thomie
    Differential Revision: https://phabricator.haskell.org/D1855
    GHC Trac Issues: #11371