-caf-all gives "Error: symbol `Mainmain_CAF_cc_ccs' is already defined"
With this module:
module Main where x = f [1..5] (f [2..] [3..]) f xs ys = l where l = [ if s then x else y | (x, y) <- zip xs ys ] s = g xs ys g  _ = True g _  = False g (x:xs) (y:ys) = g xs ys main = print (show x)
compiling with -caf-all gives:
% ghc -prof -caf-all a.hs -o a /tmp/ghc21918_0/ghc21918_0.s: Assembler messages: /tmp/ghc21918_0/ghc21918_0.s:3039:0: Error: symbol `Mainmain_CAF_cc_ccs' is already defined /tmp/ghc21918_0/ghc21918_0.s:3087:0: Error: symbol `Mainsat_CAF_cc_ccs' is already defined /tmp/ghc21918_0/ghc21918_0.s:3103:0: Error: symbol `Mainsat_CAF_cc_ccs' is already defined
The failure is similar in 6.4.2 and almost-6.6.
Reported on the haskell-cafe list.