patch applied (ghc-6.8/ghc): When complaining about non-rigid context, give suggestion of adding a signature

[Ian Lynagh]

Mon Dec 24 04:22:17 PST 2007  simonpj at microsoft.com
  * When complaining about non-rigid context, give suggestion of adding a signature

    M ./compiler/typecheck/TcPat.lhs -2 +2