patch applied (ghc): Fix Trac #3640, plus associated refactoring

[Simon Peyton Jones]

Thu Nov  5 08:55:25 PST 2009  simonpj at microsoft.com
  * Fix Trac #3640, plus associated refactoring
  Ignore-this: cf1f4ea1e8b75b4909ab395907de9eb3
  
  In fixing this bug (to do with record puns), I had the usual rush of
  blood to the head, and I did quite a bit of refactoring in the way
  that duplicate/shadowed names are reported.
  
  I think the result is shorter as well as clearer.
  
  In one place I found it convenient for the renamer to use the ErrCtxt
  carried in the monad.  (The renamer used not to have such a context,
  but years ago the typechecker and renamer monads became one, so now it
  does.)   So now it's availble if you want it in future.

    M ./compiler/rename/RnBinds.lhs -73 +50
    M ./compiler/rename/RnEnv.lhs -48 +45
    M ./compiler/rename/RnExpr.lhs -10 +9
    M ./compiler/rename/RnPat.lhs -3 +1
    M ./compiler/rename/RnSource.lhs -34 +29
    M ./compiler/rename/RnTypes.lhs -1 +1
    M ./compiler/typecheck/TcRnMonad.lhs -32 +47

View patch online:
http://darcs.haskell.org/ghc/_darcs/patches/20091105165525-1287e-cbfc3ae27a99d02ae7e0e6821bc92000f66e8bed.gz