patch applied (ghc): Fix Trac #2136: reporting of unused variables

[Simon Peyton Jones]

Thu Apr  3 04:02:50 PDT 2008  simonpj at microsoft.com
  * Fix Trac #2136: reporting of unused variables
  
  There's a bit of a hack RnBinds.rnValBindsAndThen, documented
  in Note [Unused binding hack].  But the hack was over brutal
  before, and produced unnecssarily bad (absence of) warnings.
  This patch does a bit of refactoring; and fixes the bug in
  rnValBindsAndThen.
  

    M ./compiler/rename/RnBinds.lhs -27 +38
    M ./compiler/rename/RnEnv.lhs -10 +4
    M ./compiler/rename/RnExpr.lhs -13 +13
    M ./compiler/rename/RnPat.lhs -3 +4