Restore Trees That Grow reverted commits

The following commits were reverted prior to the release of GHC 8.4.1,
because the time to derive Data instances was too long [1].

 438dd1cbba13d35f3452b4dcef3f94ce9a216905 Phab:D4147
 e3ec2e7ae94524ebd111963faf34b84d942265b4 Phab:D4177
 47ad6578ea460999b53eb4293c3a3b3017a56d65 Phab:D4186

The work is continuing, as the minimum bootstrap compiler is now
GHC 8.2.1, and this allows Plan B[2] for instances to be used.  This
will land in a following commit.

Updates Haddock submodule

[1] https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/Instances
[2] https://ghc.haskell.org/trac/ghc/wiki/ImplementingTreesThatGrow/Instances#PLANB

1 files changed, 6 insertions, 6 deletions

diff --git a/ghc/GHCi/UI/Info.hs b/ghc/GHCi/UI/Info.hs
index ad390dd433..3bb90fdf6b 100644
--- a/ghc/GHCi/UI/Info.hs
+++ b/ghc/GHCi/UI/Info.hs
@@ -323,19 +323,19 @@ processAllTypeCheckedModule tcm = do
         return $ fmap (\expr -> (mid, getLoc e, CoreUtils.exprType expr)) mbe
       where
         mid :: Maybe Id
-        mid | HsVar (L _ i) <- unwrapVar (unLoc e) = Just i
-            | otherwise                            = Nothing
+        mid | HsVar _ (L _ i) <- unwrapVar (unLoc e) = Just i
+            | otherwise                              = Nothing
 
-        unwrapVar (HsWrap _ var) = var
-        unwrapVar e'             = e'
+        unwrapVar (HsWrap _ _ var) = var
+        unwrapVar e'               = e'
 
     -- | Extract 'Id', 'SrcSpan', and 'Type' for 'LPats's
     getTypeLPat :: LPat GhcTc -> m (Maybe (Maybe Id,SrcSpan,Type))
     getTypeLPat (L spn pat) =
         pure (Just (getMaybeId pat,spn,hsPatType pat))
       where
-        getMaybeId (VarPat (L _ vid)) = Just vid
-        getMaybeId _                  = Nothing
+        getMaybeId (VarPat _ (L _ vid)) = Just vid
+        getMaybeId _                    = Nothing
 
     -- | Get ALL source spans in the source.
     listifyAllSpans :: Typeable a => TypecheckedSource -> [Located a]