diff options
Diffstat (limited to 'compiler/GHC/Core/DataCon.hs')
| -rw-r--r-- | compiler/GHC/Core/DataCon.hs | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/compiler/GHC/Core/DataCon.hs b/compiler/GHC/Core/DataCon.hs index 064cdc866f..7e18b471f3 100644 --- a/compiler/GHC/Core/DataCon.hs +++ b/compiler/GHC/Core/DataCon.hs @@ -250,6 +250,8 @@ in wrapper_reqd in GHC.Types.Id.Make.mkDataConRep. * Type variables may be permuted; see MkId Note [Data con wrappers and GADT syntax] +* Datatype contexts require dropping some dictionary arguments. + See Note [Instantiating stupid theta]. Note [The stupid context] ~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -1449,9 +1451,9 @@ dataConWrapperType :: DataCon -> Type -- mentions the family tycon, not the internal one. dataConWrapperType (MkData { dcUserTyVarBinders = user_tvbs, dcOtherTheta = theta, dcOrigArgTys = arg_tys, - dcOrigResTy = res_ty }) + dcOrigResTy = res_ty, dcStupidTheta = stupid }) = mkInvisForAllTys user_tvbs $ - mkInvisFunTysMany theta $ + mkInvisFunTysMany (stupid ++ theta) $ mkVisFunTys arg_tys $ res_ty |