diff options
Diffstat (limited to 'compiler/GHC/Tc/Gen/HsType.hs')
| -rw-r--r-- | compiler/GHC/Tc/Gen/HsType.hs | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/compiler/GHC/Tc/Gen/HsType.hs b/compiler/GHC/Tc/Gen/HsType.hs index 9e8375b47d..dd1b0c0eca 100644 --- a/compiler/GHC/Tc/Gen/HsType.hs +++ b/compiler/GHC/Tc/Gen/HsType.hs @@ -388,11 +388,11 @@ kcClassSigType :: [LocatedN Name] -> LHsSigType GhcRn -> TcM () -- meth :: forall a (x :: f a). Proxy x -> () -- When instantiating Proxy with kappa, we must unify kappa := f a. But we're -- still working out the kind of f, and thus f a will have a coercion in it. --- Coercions block unification (Note [Equalities with incompatible kinds] in --- TcCanonical) and so we fail to unify. If we try to kind-generalize, we'll --- end up promoting kappa to the top level (because kind-generalization is --- normally done right before adding a binding to the context), and then we --- can't set kappa := f a, because a is local. +-- Coercions may block unification (Note [Equalities with incompatible kinds] in +-- GHC.Tc.Solver.Equality, wrinkle (EIK2)) and so we fail to unify. If we try to +-- kind-generalize, we'll end up promoting kappa to the top level (because +-- kind-generalization is normally done right before adding a binding to the context), +-- and then we can't set kappa := f a, because a is local. kcClassSigType names sig_ty@(L _ (HsSig { sig_bndrs = hs_outer_bndrs, sig_body = hs_ty })) = addSigCtxt (funsSigCtxt names) sig_ty $ @@ -1932,7 +1932,7 @@ checkExpectedKind hs_ty ty act_kind exp_kind ; if act_kind' `tcEqType` exp_kind then return res_ty -- This is very common - else do { co_k <- uType KindLevel origin act_kind' exp_kind + else do { co_k <- unifyTypeAndEmit KindLevel origin act_kind' exp_kind ; traceTc "checkExpectedKind" (vcat [ ppr act_kind , ppr exp_kind , ppr co_k ]) |