[project @ 2001-10-22 11:37:45 by simonpj]

[project @ 2001-10-22 11:37:45 by simonpj]
-------------------------------
	Correct a nasty existential bug
	-------------------------------

	MERGE WITH STABLE BRANCH

Thanks to Volker Stolz for finding this existential bug.
Again, it's amazing that it hasn't shown up before.
GHC 5.02 allows this utterly bogus program to get past
the type checker

  data DS = forall a. C (a -> Int)

  call (C f) arg = f arg

The existential-tyvar-escape check was wrong. Easily fixed, though.

	tcfail099 now tests for this