diff options
| -rw-r--r-- | compiler/GHC/Tc/Module.hs | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/compiler/GHC/Tc/Module.hs b/compiler/GHC/Tc/Module.hs index beb4c64557..76c5f0fb66 100644 --- a/compiler/GHC/Tc/Module.hs +++ b/compiler/GHC/Tc/Module.hs @@ -1096,6 +1096,7 @@ checkBootTyCon is_boot tc1 tc2 -- Order of pattern matching matters. subDM _ Nothing _ = True subDM _ _ Nothing = False + -- If the hsig wrote: -- -- f :: a -> a @@ -1103,11 +1104,14 @@ checkBootTyCon is_boot tc1 tc2 -- -- this should be validly implementable using an old-fashioned -- vanilla default method. - subDM t1 (Just (_, GenericDM t2)) (Just (_, VanillaDM)) - = eqTypeX env t1 t2 + subDM t1 (Just (_, GenericDM gdm_t1)) (Just (_, VanillaDM)) + = eqType t1 gdm_t1 -- Take care (#22476). Both t1 and gdm_t1 come + -- from tc1, so use eqType, and /not/ eqTypeX + -- This case can occur when merging signatures subDM t1 (Just (_, VanillaDM)) (Just (_, GenericDM t2)) = eqTypeX env t1 t2 + subDM _ (Just (_, VanillaDM)) (Just (_, VanillaDM)) = True subDM _ (Just (_, GenericDM t1)) (Just (_, GenericDM t2)) = eqTypeX env t1 t2 |