I had similar problem with cabal. Installing real gcc seems to help (at least on OS X 10.8.5 Mountain Lion with Xcode 5.0.2):
brew tap homebrew/versions
brew install gcc48
# go for lunch ... or maybe movie
Then edit /Library/Frameworks/GHC.framework/Versions/7.6.3-i386/usr/lib/ghc-7.6.3/settings
(as root) and put
("C compiler command", "/usr/local/bin/gcc-4.8"),
instead of /usr/bin/gcc
Then
rm -rf ~/.ghc ~/.cabal ~/Library/Haskell
As usual be careful with rm -rf
but it seems necessary as cached version of Cabal-the-library lead to bus error even with gcc-4.8
(which suggests the problem may be with the Cabal library rather than cabal-install itself).
NB the fresh install of Haskell Platform alone did not work for me, either with or without various clang wrappers.