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| author | Krzysztof Gogolewski <krzysztof.gogolewski@tweag.io> | 2022-05-14 01:07:36 +0200 |
|---|---|---|
| committer | Krzysztof Gogolewski <krzysztof.gogolewski@tweag.io> | 2022-05-27 16:44:48 +0200 |
| commit | 3bd7d5d668b316f517a66c72fcf9bc7a36cc6ba4 (patch) | |
| tree | 186c133c0259d87f04b79c2017b7ee858b1b380a /compiler/GHC/Tc/Validity.hs | |
| parent | ed37027f713bb6563fd98d144a39211339fd91a5 (diff) | |
| download | haskell-3bd7d5d668b316f517a66c72fcf9bc7a36cc6ba4.tar.gz | |
Use a class to check validity of withDictwip/withdict
This moves handling of the magic 'withDict' function from the desugarer
to the typechecker. Details in Note [withDict].
I've extracted a part of T16646Fail to a separate file T16646Fail2,
because the new error in 'reify' hides the errors from 'f' and 'g'.
WithDict now works with casts, this fixes #21328.
Part of #19915
Diffstat (limited to 'compiler/GHC/Tc/Validity.hs')
| -rw-r--r-- | compiler/GHC/Tc/Validity.hs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/compiler/GHC/Tc/Validity.hs b/compiler/GHC/Tc/Validity.hs index 9010c43d46..22b627a36f 100644 --- a/compiler/GHC/Tc/Validity.hs +++ b/compiler/GHC/Tc/Validity.hs @@ -1407,7 +1407,7 @@ 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 ] + | clas_nm `elem` [ heqTyConName, eqTyConName, coercibleTyConName, withDictClassName ] , not quantified_constraint = failWithTc $ TcRnSpecialClassInst clas False |