Upgrade UniqSet to a newtype

The fundamental problem with `type UniqSet = UniqFM` is that `UniqSet`
has a key invariant `UniqFM` does not. For example, `fmap` over
`UniqSet` will generally produce nonsense.

* Upgrade `UniqSet` from a type synonym to a newtype.

* Remove unused and shady `extendVarSet_C` and `addOneToUniqSet_C`.

* Use cached unique in `tyConsOfType` by replacing
  `unitNameEnv (tyConName tc) tc` with `unitUniqSet tc`.

Reviewers: austin, hvr, goldfire, simonmar, niteria, bgamari

Reviewed By: niteria

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D3146

2 files changed, 6 insertions, 6 deletions

diff --git a/compiler/rename/RnBinds.hs b/compiler/rename/RnBinds.hs
index f6a22f5df2..f8b3347ca5 100644
--- a/compiler/rename/RnBinds.hs
+++ b/compiler/rename/RnBinds.hs
@@ -48,7 +48,7 @@ import Bag
 import Util
 import Outputable
 import FastString
-import UniqFM
+import UniqSet
 import Maybes           ( orElse )
 import qualified GHC.LanguageExtensions as LangExt
 
@@ -528,8 +528,8 @@ depAnalBinds binds_w_dus
   = (map get_binds sccs, map get_du sccs)
   where
     sccs = depAnal (\(_, defs, _) -> defs)
-                   (\(_, _, uses) -> nonDetEltsUFM uses)
-                   -- It's OK to use nonDetEltsUFM here as explained in
+                   (\(_, _, uses) -> nonDetEltsUniqSet uses)
+                   -- It's OK to use nonDetEltsUniqSet here as explained in
                    -- Note [depAnal determinism] in NameEnv.
                    (bagToList binds_w_dus)
 
diff --git a/compiler/rename/RnSource.hs b/compiler/rename/RnSource.hs
index 3e462744e1..601d45b90e 100644
--- a/compiler/rename/RnSource.hs
+++ b/compiler/rename/RnSource.hs
@@ -51,7 +51,7 @@ import HscTypes         ( HscEnv, hsc_dflags )
 import ListSetOps       ( findDupsEq, removeDups, equivClasses )
 import Digraph          ( SCC, flattenSCC, flattenSCCs
                         , stronglyConnCompFromEdgedVerticesUniq )
-import UniqFM
+import UniqSet
 import qualified GHC.LanguageExtensions as LangExt
 
 import Control.Monad
@@ -1348,7 +1348,7 @@ depAnalTyClDecls :: GlobalRdrEnv
 depAnalTyClDecls rdr_env ds_w_fvs
   = stronglyConnCompFromEdgedVerticesUniq edges
   where
-    edges = [ (d, tcdName (unLoc d), map (getParent rdr_env) (nonDetEltsUFM fvs))
+    edges = [ (d, tcdName (unLoc d), map (getParent rdr_env) (nonDetEltsUniqSet fvs))
             | (d, fvs) <- ds_w_fvs ]
             -- It's OK to use nonDetEltsUFM here as
             -- stronglyConnCompFromEdgedVertices is still deterministic
@@ -1357,7 +1357,7 @@ depAnalTyClDecls rdr_env ds_w_fvs
 
 toParents :: GlobalRdrEnv -> NameSet -> NameSet
 toParents rdr_env ns
-  = nonDetFoldUFM add emptyNameSet ns
+  = nonDetFoldUniqSet add emptyNameSet ns
   -- It's OK to use nonDetFoldUFM because we immediately forget the
   -- ordering by creating a set
   where