[project @ 2003-11-03 15:26:22 by simonpj]

The generic to/from methods for derivable type classes should only
be generated for types in the current group, rather than all the
in-scope tycons.  Otherwise they get generated multiple times in
a Template-Haskell situation.

diff --git a/ghc/compiler/typecheck/TcDeriv.lhs b/ghc/compiler/typecheck/TcDeriv.lhs
index 911da5c..a9e1a83 100644 (file)
--- a/ghc/compiler/typecheck/TcDeriv.lhs
+++ b/ghc/compiler/typecheck/TcDeriv.lhs
@@ -16,7 +16,7 @@ import RdrHsSyn               ( RdrNameMonoBinds )
 import RnHsSyn         ( RenamedHsBinds, RenamedTyClDecl, RenamedHsPred )
 import CmdLineOpts     ( DynFlag(..) )
 
-import Generics                ( mkGenericBinds )
+import Generics                ( mkTyConGenericBinds )
 import TcRnMonad
 import TcEnv           ( newDFunName, 
                          InstInfo(..), pprInstInfo, InstBindings(..),
@@ -43,7 +43,7 @@ import Name           ( Name, getSrcLoc )
 import NameSet         ( NameSet, emptyNameSet, duDefs )
 import Unique          ( Unique, getUnique )
 
-import TyCon           ( tyConTyVars, tyConDataCons, tyConArity, 
+import TyCon           ( tyConTyVars, tyConDataCons, tyConArity, tyConHasGenerics,
                          tyConTheta, isProductTyCon, isDataTyCon,
                          isEnumerationTyCon, isRecursiveTyCon, TyCon
                        )
@@ -211,8 +211,7 @@ tcDeriving tycl_decls
                -- before tacking the "ordinary" ones
 
        -- Generate the generic to/from functions from each type declaration
-       ; tcg_env <- getGblEnv
-       ; let gen_binds = mkGenericBinds (typeEnvTyCons (tcg_type_env tcg_env))
+       ; gen_binds <- mkGenericBinds tycl_decls
        ; let inst_info  = newtype_inst_info ++ ordinary_inst_info
 
        -- Rename these extra bindings, discarding warnings about unused bindings etc
@@ -254,6 +253,13 @@ deriveOrdinaryStuff eqns
 
        -- Done
        ; returnM (inst_infos, andMonoBindList (extra_binds : aux_binds_s)) }
+
+-----------------------------------------
+mkGenericBinds tycl_decls
+  = do { tcs <- mapM tcLookupTyCon [tc_name | TyData { tcdName = tc_name } <- tycl_decls]
+               -- We are only interested in the data type declarations
+       ; return (andMonoBindList [mkTyConGenericBinds tc | tc <- tcs, tyConHasGenerics tc]) }
+               -- And then only in the ones whose 'has-generics' flag is on
 \end{code}
 
 

diff --git a/ghc/compiler/types/Generics.lhs b/ghc/compiler/types/Generics.lhs
index a0297ad..4ea84dc 100644 (file)
--- a/ghc/compiler/types/Generics.lhs
+++ b/ghc/compiler/types/Generics.lhs
@@ -1,5 +1,5 @@
 \begin{code}
-module Generics ( canDoGenerics, mkGenericBinds,
+module Generics ( canDoGenerics, mkTyConGenericBinds,
                  mkGenericRhs, 
                  validGenericInstanceType, validGenericMethodType
     ) where
@@ -248,12 +248,8 @@ canDoGenerics data_cons
 type US = Int  -- Local unique supply, just a plain Int
 type FromAlt = (Pat RdrName, HsExpr RdrName)
 
-mkGenericBinds :: [TyCon] -> MonoBinds RdrName
-mkGenericBinds tcs = andMonoBindList [ mkTyConGenBinds tc 
-                                    | tc <- tcs, tyConHasGenerics tc]
-
-mkTyConGenBinds :: TyCon -> MonoBinds RdrName
-mkTyConGenBinds tycon
+mkTyConGenericBinds :: TyCon -> MonoBinds RdrName
+mkTyConGenericBinds tycon
   = FunMonoBind from_RDR False {- Not infix -}
                [mkSimpleHsAlt pat rhs | (pat,rhs) <- from_alts]
                loc