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author | Simon Peyton Jones <simon.peytonjones@gmail.com> | 2022-12-19 22:58:07 +0000 |
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committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2022-12-21 14:32:30 -0500 |
commit | 3d55d8ab51ece43c51055c43c9e7aba77cce46c0 (patch) | |
tree | 5f4450f04c43ca0e56342d2f9f8312f576e4a5bf /compiler | |
parent | e193e53790dd5886feea3cf4c9c17625d188291b (diff) | |
download | haskell-3d55d8ab51ece43c51055c43c9e7aba77cce46c0.tar.gz |
Fix an assertion check in addToEqualCtList
The old assertion saw that a constraint ct could rewrite itself
(of course it can) and complained (stupid).
Fixes #22645
Diffstat (limited to 'compiler')
-rw-r--r-- | compiler/GHC/Tc/Solver/Types.hs | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/compiler/GHC/Tc/Solver/Types.hs b/compiler/GHC/Tc/Solver/Types.hs index 4c52721638..e6ee09b0d8 100644 --- a/compiler/GHC/Tc/Solver/Types.hs +++ b/compiler/GHC/Tc/Solver/Types.hs @@ -273,21 +273,29 @@ addToEqualCtList ct old_eqs | debugIsOn = case ct of CEqCan { cc_lhs = TyVarLHS tv } -> - let shares_lhs (CEqCan { cc_lhs = TyVarLHS old_tv }) = tv == old_tv - shares_lhs _other = False - in - assert (all shares_lhs old_eqs) $ - assert (null ([ (ct1, ct2) | ct1 <- ct : old_eqs - , ct2 <- ct : old_eqs - , let { fr1 = ctFlavourRole ct1 - ; fr2 = ctFlavourRole ct2 } - , fr1 `eqCanRewriteFR` fr2 ])) $ + assert (all (shares_lhs tv) old_eqs) $ + assertPpr (null bad_prs) + (vcat [ text "bad_prs" <+> ppr bad_prs + , text "ct:old_eqs" <+> ppr (ct : old_eqs) ]) $ (ct : old_eqs) _ -> pprPanic "addToEqualCtList not CEqCan" (ppr ct) | otherwise = ct : old_eqs + where + shares_lhs tv (CEqCan { cc_lhs = TyVarLHS old_tv }) = tv == old_tv + shares_lhs _ _ = False + bad_prs = filter is_bad_pair (distinctPairs (ct : old_eqs)) + is_bad_pair (ct1,ct2) = ctFlavourRole ct1 `eqCanRewriteFR` ctFlavourRole ct2 + +distinctPairs :: [a] -> [(a,a)] +-- distinctPairs [x1,...xn] is the list of all pairs [ ...(xi, xj)...] +-- where i /= j +-- NB: does not return pairs (xi,xi), which would be stupid in the +-- context of addToEqualCtList (#22645) +distinctPairs [] = [] +distinctPairs (x:xs) = concatMap (\y -> [(x,y),(y,x)]) xs ++ distinctPairs xs -- returns Nothing when the new list is empty, to keep the environments smaller filterEqualCtList :: (Ct -> Bool) -> EqualCtList -> Maybe EqualCtList |