[commit: ghc] tc-untouchables: Use System Names for evidence variables (2b523dc)

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : tc-untouchables

http://hackage.haskell.org/trac/ghc/changeset/2b523dc3c589f64d062dd4ed79a6bd24d2c37460

>---------------------------------------------------------------

commit 2b523dc3c589f64d062dd4ed79a6bd24d2c37460
Author: Simon Peyton Jones <[email protected]>
Date:   Mon Oct 1 10:36:13 2012 +0100

    Use System Names for evidence variables
    
    These variables all have uniformative names like "cobox" or "d".
    Make them System Names tells the pretty printer to show their
    uniques even without -dppr-debug.  That in turn makes the
    less-voluminous debug traces *much* more informative.

>---------------------------------------------------------------

 compiler/typecheck/TcMType.lhs   |    6 +++---
 compiler/typecheck/TcRnMonad.lhs |    5 +++++
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/compiler/typecheck/TcMType.lhs b/compiler/typecheck/TcMType.lhs
index 8773078..5037ade 100644
--- a/compiler/typecheck/TcMType.lhs
+++ b/compiler/typecheck/TcMType.lhs
@@ -155,17 +155,17 @@ newWantedEvVars theta = mapM newWantedEvVar theta
 
 newEvVar :: TcPredType -> TcM EvVar
 -- Creates new *rigid* variables for predicates
-newEvVar ty = do { name <- newName (predTypeOccName ty) 
+newEvVar ty = do { name <- newSysName (predTypeOccName ty) 
                  ; return (mkLocalId name ty) }
 
 newEq :: TcType -> TcType -> TcM EvVar
 newEq ty1 ty2
-  = do { name <- newName (mkVarOccFS (fsLit "cobox"))
+  = do { name <- newSysName (mkVarOccFS (fsLit "cobox"))
        ; return (mkLocalId name (mkTcEqPred ty1 ty2)) }
 
 newDict :: Class -> [TcType] -> TcM DictId
 newDict cls tys 
-  = do { name <- newName (mkDictOcc (getOccName cls))
+  = do { name <- newSysName (mkDictOcc (getOccName cls))
        ; return (mkLocalId name (mkClassPred cls tys)) }
 
 predTypeOccName :: PredType -> OccName
diff --git a/compiler/typecheck/TcRnMonad.lhs b/compiler/typecheck/TcRnMonad.lhs
index c40a9f7..68301f7 100644
--- a/compiler/typecheck/TcRnMonad.lhs
+++ b/compiler/typecheck/TcRnMonad.lhs
@@ -376,6 +376,11 @@ newName occ
        ; loc  <- getSrcSpanM
        ; return (mkInternalName uniq occ loc) }
 
+newSysName :: OccName -> TcM Name
+newSysName occ
+  = do { uniq <- newUnique
+       ; return (mkSystemName uniq occ) }
+
 newSysLocalIds :: FastString -> [TcType] -> TcRnIf gbl lcl [TcId]
 newSysLocalIds fs tys
   = do  { us <- newUniqueSupply