Allow deriving Typeable for more tycons

ghc · May 7, 2013 · 92191a3 · 92191a3
1 parent c041b62
commit 92191a3
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs
@@ -683,7 +683,8 @@ mkEqnHelp :: CtOrigin -> [TyVar] -> Class -> [Type] -> Type
 
 mkEqnHelp orig tvs cls cls_tys tc_app mtheta
   | Just (tycon, tc_args) <- tcSplitTyConApp_maybe tc_app
-  , isAlgTyCon tycon    -- Check for functions, primitive types etc
+  , className cls == typeableClassName || isAlgTyCon tycon
+  -- Avoid functions, primitive types, etc, unless it's Typeable
   = mk_alg_eqn tycon tc_args
   | otherwise
   = failWithTc (derivingThingErr False cls cls_tys tc_app