patch applied (ghc): Fix Trac #3219: type of a record update

[Simon Peyton Jones]

Wed May 13 08:09:22 PDT 2009  simonpj at microsoft.com
  * Fix Trac #3219: type of a record update
  Ignore-this: 95af0b6c81a888839528327905f849fa
  
  Record updates are amazingly hard to typecheck right.  This is one place
  where GHC's policy of typechecking the original source is much harder than
  desugaring and typechecking that!
  
  Anyway, the bug here is that to compute the 'fixed' type variables I was
  only looking at one constructor rather than all the relevant_cons
  
  Test is typecheck/should_compile/T3219, which GHC 6.10 barfs on (with Lint).
  

    M ./compiler/typecheck/TcExpr.lhs -28 +41

View patch online:
http://darcs.haskell.org/ghc/_darcs/patches/20090513150922-1287e-9151bc714850547e0c9fadaab426b5484e8fe174.gz