Fix Trac #3012: allow more free-wheeling in standalone deriving

[ghc-hetmet.git] / compiler / typecheck / TcEnv.lhs

diff --git a/compiler/typecheck/TcEnv.lhs b/compiler/typecheck/TcEnv.lhs
index d1a10cf..055fc2c 100644 (file)
--- a/compiler/typecheck/TcEnv.lhs
+++ b/compiler/typecheck/TcEnv.lhs
@@ -640,6 +640,7 @@ data InstBindings a
        (LHsBinds a)            -- Bindings for the instance methods
        [LSig a]                -- User pragmas recorded for generating 
                                -- specialised instances
+       Bool                    -- True <=> This code came from a standalone deriving clause
 
   | NewTypeDerived              -- Used for deriving instances of newtypes, where the
        CoercionI               -- witness dictionary is identical to the argument 
@@ -655,8 +656,8 @@ pprInstInfo info = vcat [ptext (sLit "InstInfo:") <+> ppr (idType (iDFunId info)
 pprInstInfoDetails :: OutputableBndr a => InstInfo a -> SDoc
 pprInstInfoDetails info = pprInstInfo info $$ nest 2 (details (iBinds info))
   where
-    details (VanillaInst b _)  = pprLHsBinds b
-    details (NewTypeDerived _) = text "Derived from the representation type"
+    details (VanillaInst b _ _) = pprLHsBinds b
+    details (NewTypeDerived _)  = text "Derived from the representation type"
 
 simpleInstInfoClsTy :: InstInfo a -> (Class, Type)
 simpleInstInfoClsTy info = case instanceHead (iSpec info) of