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| author | Simon Peyton Jones <simon.peytonjones@gmail.com> | 2022-11-18 22:54:31 +0000 |
|---|---|---|
| committer | Simon Peyton Jones <simon.peytonjones@gmail.com> | 2022-11-19 22:12:38 +0000 |
| commit | 458ba4b2934c82adeefdb75d6922d4563e8f4399 (patch) | |
| tree | 20ad817fcfca41af08d4f901dcdcd6976761d16a | |
| parent | e8f2b80da6429af05d5e8ef1a0937aae8c22f819 (diff) | |
| download | haskell-wip/T22476.tar.gz | |
Buglet in GHC.Tc.Module.checkBootTyConwip/T22476
This lurking bug used the wrong function to compare two
types in GHC.Tc.Module.checkBootTyCon
It's hard to trigger the bug, which only came up during
!9343, so there's no regression test in this MR.
| -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 |