patch applied (ghc-7.0/ghc): Ensure that instance overlap errors are report properly

[Ian Lynagh]

Mon Nov 15 06:28:05 PST 2010  simonpj at microsoft.com
  * Ensure that instance overlap errors are report properly
  
  This (annoyingly) requires us to re-flatten the class predicate.
  See Note [Flattening in error message generation]

    M ./compiler/typecheck/TcErrors.lhs -37 +91

View patch online:
http://darcs.haskell.org/cgi-bin/darcsweb.cgi?r=ghc-7.0/ghc;a=darcs_commitdiff;h=20101115142805-1287e-ba1adb6fda4cb20041ec0d8fe7021b2910ac5837.gz