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d74825b9
by Simon Peyton Jones at 2025-12-08T10:28:57+00:00
```
Wibble
```

@@ -648,6 +648,7 @@ reportWanteds ctxt tc_lvl wc@(WC { wc_simple = simples, wc_impl = implics
                , ("Homo eqs",      is_homo_equality,  True,  mkGroupReporter mkEqErr)
                , ("Other eqs",     is_equality,       True,  mkGroupReporter mkEqErr)
 +              , ("Insoluble fundeps", is_insoluble_fundep, True, mkGroupReporter mkDictErr)
+               ]
      -- report2: we suppress these if there are insolubles elsewhere in the tree
@@ -665,6 +666,11 @@ reportWanteds ctxt tc_lvl wc@(WC { wc_simple = simples, wc_impl = implics
         | otherwise         = False
         -- I think all given residuals are equalities
 +    -- Constraints that have insoluble functional dependencies
 +    is_insoluble_fundep item _ = case ei_m_reason item of
 +           Just InsolubleFunDepReason -> True
 +           _                          -> False
++
      -- Things like (Int ~N Bool)
      utterly_wrong _ (EqPred NomEq ty1 ty2) = isRigidTy ty1 && isRigidTy ty2
      utterly_wrong _ _                      = False

@@ -5423,7 +5423,7 @@ getUserGivens (CEC {cec_encl = implics}) = getUserGivensFromImplics implics
  -- that will give rise to a diagnostic.
  data ErrorItem
  -- We could perhaps use Ct here (and indeed used to do exactly that), but
 --- having a separate type gives to denote errors-in-formation gives us
 +-- having a separate type to denote error-information gives us
  -- a nice place to do pre-processing, such as calculating ei_suppress.
  -- Perhaps some day, an ErrorItem could eventually evolve to contain
  -- the error text (or some representation of it), so we can then have all
@@ -5436,7 +5436,7 @@ data ErrorItem
           --   for Givens, Nothing
         , ei_flavour  :: CtFlavour
         , ei_loc      :: CtLoc
 -       , ei_m_reason :: Maybe CtIrredReason  -- if this ErrorItem was made from a
 +       , ei_m_reason :: Maybe CtIrredReason  -- If this ErrorItem was made from a
                                               -- CtIrred, this stores the reason
         , ei_suppress :: Bool    -- Suppress because of
                                  -- Note [Wanteds rewrite Wanteds: rewriter-sets]