X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcClassDcl.lhs;h=67f2945464d1eb9ce11303ba63a2a4952fba18fc;hb=7e76baf009923981e5c277afd4bc8b14913dbf04;hp=87c18414ea3abc400c29e68c13d0be6b2d49c845;hpb=e07e74e5a074490d25443aeff4db4f1f299040c4;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcClassDcl.lhs b/compiler/typecheck/TcClassDcl.lhs
index 87c1841..67f2945 100644
--- a/compiler/typecheck/TcClassDcl.lhs
+++ b/compiler/typecheck/TcClassDcl.lhs
@@ -425,7 +425,7 @@ mkMethId origin clas sel_id inst_tys
 	rho_ty	     = ASSERT( length tyvars == length inst_tys )
 		       substTyWith tyvars inst_tys rho
 	(preds,tau)  = tcSplitPhiTy rho_ty
-        first_pred   = head preds
+        first_pred   = ASSERT( not (null preds)) head preds
     in
 	-- The first predicate should be of form (C a b)
 	-- where C is the class in question
@@ -452,8 +452,7 @@ mkMethId origin clas sel_id inst_tys
 	getSrcSpanM			`thenM` \ loc ->
 	let 
 	    real_tau = mkPhiTy (tail preds) tau
-	    meth_id  = mkUserLocal (getOccName sel_id) uniq real_tau 
-			(srcSpanStart loc) --TODO
+	    meth_id  = mkUserLocal (getOccName sel_id) uniq real_tau loc
 	in
 	returnM (Nothing, meth_id)
 
@@ -529,7 +528,7 @@ mkDefMethRhs origin clas inst_tys sel_id loc GenDefMeth
 	  -- case we require that the instance decl is for a single-parameter
 	  -- type class with type variable arguments:
 	  --	instance (...) => C (T a b)
-    clas_tyvar    = head (classTyVars clas)
+    clas_tyvar    = ASSERT (not (null (classTyVars clas))) head (classTyVars clas)
     Just tycon	  = maybe_tycon
     maybe_tycon   = case inst_tys of 
 			[ty] -> case tcSplitTyConApp_maybe ty of
@@ -707,7 +706,7 @@ mkGenericInstance clas (hs_ty, binds)
 	-- Make the dictionary function.
     getSrcSpanM						`thenM` \ span -> 
     getOverlapFlag					`thenM` \ overlap_flag -> 
-    newDFunName clas [inst_ty] (srcSpanStart span)	`thenM` \ dfun_name ->
+    newDFunName clas [inst_ty] span             	`thenM` \ dfun_name ->
     let
 	inst_theta = [mkClassPred clas [mkTyVarTy tv] | tv <- tyvars]
 	dfun_id    = mkDictFunId dfun_name tyvars inst_theta clas [inst_ty]
@@ -734,7 +733,7 @@ tcAddDeclCtxt decl thing_inside
 				 else "data type" ++ maybeInst
 	   | isFamilyDecl decl = "family"
 
-     maybeInst | isFamInstDecl decl = " family"
+     maybeInst | isFamInstDecl decl = " instance"
 	       | otherwise          = ""
 
      ctxt = hsep [ptext SLIT("In the"), text thing,