diff options
Diffstat (limited to 'compiler/GHC/Tc/Validity.hs')
| -rw-r--r-- | compiler/GHC/Tc/Validity.hs | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/compiler/GHC/Tc/Validity.hs b/compiler/GHC/Tc/Validity.hs index 250811b99e..da51f7245f 100644 --- a/compiler/GHC/Tc/Validity.hs +++ b/compiler/GHC/Tc/Validity.hs @@ -1503,7 +1503,9 @@ check_special_inst_head dflags is_boot is_sig ctxt clas cls_args -- instances for (~), (~~), or Coercible; -- but we DO want to allow them in quantified constraints: -- f :: (forall a b. Coercible a b => Coercible (m a) (m b)) => ...m... - | clas_nm `elem` [ heqTyConName, eqTyConName, coercibleTyConName, withDictClassName ] + | clas_nm `elem` + [ heqTyConName, eqTyConName, coercibleTyConName + , withDictClassName, unsatisfiableClassName ] , not quantified_constraint = failWithTc $ TcRnSpecialClassInst clas False |