Wibbles from Simon and Pedro

compiler/typecheck/TcDeriv.lhs

@@ -1491,10 +1491,10 @@ genDerivStuff loc fix_env clas name tycon
   | className clas `elem` typeableClassNames
   = return (gen_Typeable_binds loc tycon, emptyBag)
 
-  | classKey clas == genClassKey
+  | classKey clas == genClassKey   -- Special case because monadic
   = gen_Generic_binds tycon (nameModule name)
 
-  | otherwise
+  | otherwise	                   -- Non-monadic generators
   = case assocMaybe gen_list (getUnique clas) of
         Just gen_fn -> return (gen_fn loc tycon)
         Nothing	    -> pprPanic "genDerivStuff: bad derived class" (ppr clas)

compiler/typecheck/TcGenDeriv.lhs

@@ -70,28 +70,24 @@ import Data.List        ( partition, intersperse )
 \begin{code}
 type BagDerivStuff = Bag DerivStuff
 
-data DerivStuff     -- Please add this auxiliary stuff
+data AuxBindSpec
   = DerivCon2Tag TyCon  -- The con2Tag for given TyCon
   | DerivTag2Con TyCon  -- ...ditto tag2Con
   | DerivMaxTag  TyCon  -- ...and maxTag
+  deriving( Eq )
   -- All these generate ZERO-BASED tag operations
   -- I.e first constructor has tag 0
 
+data DerivStuff     -- Please add this auxiliary stuff
+  = DerivAuxBind AuxBindSpec
+
   -- Generics
   | DerivTyCon TyCon      -- New data types
   | DerivFamInst TyCon    -- New type family instances
 
   -- New top-level auxiliary bindings 
   | DerivHsBind (LHsBind RdrName, LSig RdrName) -- Also used for SYB
   | DerivInst (InstInfo RdrName)                -- New, auxiliary instances
-
-isDupAux :: DerivStuff -> DerivStuff -> Bool
-isDupAux (DerivCon2Tag tc1) (DerivCon2Tag tc2) = tc1 == tc2
-isDupAux (DerivTag2Con tc1) (DerivTag2Con tc2) = tc1 == tc2
-isDupAux (DerivMaxTag tc1)  (DerivMaxTag tc2)  = tc1 == tc2
-isDupAux (DerivTyCon tc1)   (DerivTyCon tc2)   = tc1 == tc2
-isDupAux (DerivFamInst tc1) (DerivFamInst tc2) = tc1 == tc2
-isDupAux _                   _                 = False
 \end{code}
 
 

compiler/types/Generics.lhs

@@ -2,6 +2,9 @@
 % (c) The University of Glasgow 2011
 %
 
+The deriving code for the Generic class
+(equivalent to the code in TcGenDeriv, for other classes)
+
 \begin{code}
 
 module Generics ( canDoGenerics,