Ticket #3344 (closed feature request: fixed)
request earlier and more perspicuous detection of tab characters in compiler/ghc.cabal.in
It turns out that if there is a tab character in compiler/ghc.cabal.in then the build fails in a way that I at least found hard to diagnose. Since the configure script builds compiler/ghc.cabal from compiler/ghc.cabal.in, life would be a lot simpler if the build fell over at that point with an error saying that tab characters are forbidden in that file.
Since I believe the tab character is a tool of Satan, I would not dream of suggesting that the configure script run expand(1) over the offending file.