Revert multiple commits

This reverts multiple commits from Simon:

  - 04a484eafc9eb9f8774b4bdd41a5dc6c9f640daf Test Trac #10359
  - a9ccd37add8315e061c02e5bf26c08f05fad9ac9 Test Trac #10403
  - c0aae6f699cbd222d826d0b8d78d6cb3f682079e Test Trac #10248
  - eb6ca851f553262efe0824b8dcbe64952de4963d Make the "matchable-given" check happen first
  - ca173aa30467a0b1023682d573fcd94244d85c50 Add a case to checkValidTyCon
  - 51cbad15f86fca1d1b0e777199eb1079a1b64d74 Update haddock submodule
  - 6e1174da5b8e0b296f5bfc8b39904300d04eb5b7 Separate transCloVarSet from fixVarSet
  - a8493e03b89f3b3bfcdb6005795de050501f5c29 Fix imports in HscMain (stage2)
  - a154944bf07b2e13175519bafebd5a03926bf105 Two wibbles to fix the build
  - 5910a1bc8142b4e56a19abea104263d7bb5c5d3f Change in capitalisation of error msg
  - 130e93aab220bdf14d08028771f83df210da340b Refactor tuple constraints
  - 8da785d59f5989b9a9df06386d5bd13f65435bc0 Delete commented-out line

These break the build by causing Haddock to fail mysteriously when
trying to examine GHC.Prim it seems.

1 files changed, 17 insertions, 15 deletions

diff --git a/compiler/typecheck/FunDeps.hs b/compiler/typecheck/FunDeps.hs
index 830873c1b9..53ecb48cc7 100644
--- a/compiler/typecheck/FunDeps.hs
+++ b/compiler/typecheck/FunDeps.hs
@@ -23,7 +23,6 @@ import Name
 import Var
 import Class
 import Type
-import TcType( immSuperClasses )
 import Unify
 import InstEnv
 import VarSet
@@ -446,29 +445,32 @@ oclose :: [PredType] -> TyVarSet -> TyVarSet
 -- See Note [The liberal coverage condition]
 oclose preds fixed_tvs
   | null tv_fds = fixed_tvs -- Fast escape hatch for common case.
-  | otherwise   = fixVarSet extend fixed_tvs
+  | otherwise   = loop fixed_tvs
   where
-    extend fixed_tvs = foldl add fixed_tvs tv_fds
-       where
-          add fixed_tvs (ls,rs)
-            | ls `subVarSet` fixed_tvs = fixed_tvs `unionVarSet` rs
-            | otherwise                = fixed_tvs
+    loop fixed_tvs
+      | new_fixed_tvs `subVarSet` fixed_tvs = fixed_tvs
+      | otherwise                           = loop new_fixed_tvs
+      where new_fixed_tvs = foldl extend fixed_tvs tv_fds
+
+    extend fixed_tvs (ls,rs)
+        | ls `subVarSet` fixed_tvs = fixed_tvs `unionVarSet` rs
+        | otherwise                = fixed_tvs
 
     tv_fds  :: [(TyVarSet,TyVarSet)]
     tv_fds  = [ (tyVarsOfTypes xs, tyVarsOfTypes ys)
-              | (xs, ys) <- concatMap determined preds ]
+              | (xs, ys) <- concatMap determined preds
+              ]
 
     determined :: PredType -> [([Type],[Type])]
     determined pred
        = case classifyPredType pred of
+            ClassPred cls tys ->
+               do let (cls_tvs, cls_fds) = classTvsFds cls
+                  fd <- cls_fds
+                  return (instFD fd cls_tvs tys)
             EqPred NomEq t1 t2 -> [([t1],[t2]), ([t2],[t1])]
-            ClassPred cls tys -> local_fds ++ concatMap determined superclasses
-              where
-               local_fds = [ instFD fd cls_tvs tys
-                           | fd <- cls_fds ]
-               (cls_tvs, cls_fds) = classTvsFds cls
-               superclasses = immSuperClasses cls tys
-            _ -> []
+            TuplePred ts       -> concatMap determined ts
+            _                  -> []
 
 {-
 ************************************************************************