From 957b762c4db8d3f2f3673e3595ec80c2d64a3274 Mon Sep 17 00:00:00 2001
From: "simonpj@microsoft.com" <unknown>
Date: Thu, 11 Jan 2007 09:09:22 +0000
Subject: [PATCH] Comments

---
 compiler/typecheck/TcDeriv.lhs |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs
index af53740..4bad739 100644
--- a/compiler/typecheck/TcDeriv.lhs
+++ b/compiler/typecheck/TcDeriv.lhs
@@ -420,6 +420,7 @@ baleOut err = addErrTc err >> returnM (Nothing, Nothing)
 \begin{code}
 mkDataTypeEqn orig gla_exts tvs cls cls_tys tycon tc_args rep_tc rep_tc_args
   | Just err <- checkSideConditions gla_exts cls cls_tys rep_tc
+	-- NB: pass the *representation* tycon to checkSideConditions
   = baleOut (derivingThingErr cls cls_tys (mkTyConApp tycon tc_args) err)
 
   | otherwise 
@@ -496,7 +497,11 @@ sideConditions
 	(dataClassKey,	   cond_glaExts `andCond` cond_std)
     ]
 
-type Condition = (Bool, TyCon) -> Maybe SDoc	-- Nothing => OK
+type Condition = (Bool, TyCon) -> Maybe SDoc
+	-- Bool is gla-exts flag
+	-- TyCon is the *representation* tycon if the 
+	--	data type is an indexed one
+	-- Nothing => OK
 
 orCond :: Condition -> Condition -> Condition
 orCond c1 c2 tc 
-- 
1.7.10.4