diff options
Diffstat (limited to 'compiler/GHC/Core/Unify.hs')
| -rw-r--r-- | compiler/GHC/Core/Unify.hs | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/compiler/GHC/Core/Unify.hs b/compiler/GHC/Core/Unify.hs index 709ccf10b4..29d2ae975c 100644 --- a/compiler/GHC/Core/Unify.hs +++ b/compiler/GHC/Core/Unify.hs @@ -957,7 +957,12 @@ unify_ty :: UMEnv -- Respects newtypes, PredTypes unify_ty env ty1 ty2 kco - -- Use tcView, not coreView. See Note [coreView vs tcView] in GHC.Core.Type. + -- See Note [Comparing nullary type synonyms] in GHC.Core.Type. + | TyConApp tc1 [] <- ty1 + , TyConApp tc2 [] <- ty2 + , tc1 == tc2 = return () + + -- TODO: More commentary needed here | Just ty1' <- tcView ty1 = unify_ty env ty1' ty2 kco | Just ty2' <- tcView ty2 = unify_ty env ty1 ty2' kco | CastTy ty1' co <- ty1 = if um_unif env |