I have not been following the recent work on Cabal, but I tried to build in the gap before this patch was committed.  I

Fri Aug  3 18:57:01 GMT Daylight Time 2007  Thomas Schilling <nominolo@gmail.com>

  * Fix tab in Cabal.cabal.

I was surprised to find that tabs are disallowed in cabal files.  Is that really the intention?  It seems like a pitfall for the unwary!  At the very least, if they must be disallowed, could the error message be more informative?  At the moment we get

                Setup.exe: Cabal.cabal:70: Unrecognized field format: 'Distribution.Simple.SetupWrapper,'

It’d be better to get

                Setup.exe: Cabal.cabal:70: illegal tab character: replace with spaces

Simon