From: bringert@cs.chalmers.se <unknown>
Date: Fri, 15 Sep 2006 23:33:15 +0000 (+0000)
Subject: Instantiate data constructor type variables with the type constructor type variables... 
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=45b391025ccd6f91d6c280c7d0e5e755b67e760c

Instantiate data constructor type variables with the type constructor type variables in constraints for derived class instances. Fixes instance deriving for GADTs which declar H98 types, closing ticket #902.
---

diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs
index 601f0de..65c425d 100644
--- a/compiler/typecheck/TcDeriv.lhs
+++ b/compiler/typecheck/TcDeriv.lhs
@@ -31,10 +31,10 @@ import RnEnv		( bindLocalNames )
 import HscTypes		( FixityEnv )
 
 import Class		( className, classArity, classKey, classTyVars, classSCTheta, Class )
-import Type		( zipOpenTvSubst, substTheta, pprThetaArrow, pprClassPred )
+import Type		( zipOpenTvSubst, substTheta, pprThetaArrow, pprClassPred, mkTyVarTy )
 import ErrUtils		( dumpIfSet_dyn )
 import MkId		( mkDictFunId )
-import DataCon		( isNullarySrcDataCon, isVanillaDataCon, dataConOrigArgTys )
+import DataCon		( isNullarySrcDataCon, isVanillaDataCon, dataConOrigArgTys, dataConInstOrigArgTys )
 import Maybes		( catMaybes )
 import RdrName		( RdrName )
 import Name		( Name, getSrcLoc )
@@ -568,7 +568,7 @@ mkDataTypeEqn tycon clas
     ordinary_constraints
       = [ mkClassPred clas [arg_ty] 
         | data_con <- tyConDataCons tycon,
-          arg_ty   <- dataConOrigArgTys data_con,
+          arg_ty <- dataConInstOrigArgTys data_con (map mkTyVarTy (tyConTyVars tycon)),
           not (isUnLiftedType arg_ty)	-- No constraints for unlifted types?
         ]