Hi,
extractBitMasks bits = [bm | bm <- [minBound..maxBound], bits `containsBitMask` bm]
Sadly this does not work since [minBound..maxBound] uses succ to enmerate the flags and the Enum instance that c2hs generates does not include a definition of succ and the default assumes that the enum is packed whereas of course for flags it is sparse (only has values for 2^n). We had this bug in gtk2hs too:
toFlags :: Flags a => Int -> [a] toFlags n = andNum n minBound where andNum n m = (if (n .|. fromEnum m) == n then (m:) else id) (if fromEnum m==fromEnum (maxBound `asTypeOf` m) then [] else andNum n (succ m))
We changed this to:
toFlags :: Flags a => Int -> [a] toFlags f = testBits f 1 where testBits f n | f == 0 = [] | f `testBit` 0 = toEnum n : testBits (f `shiftR` 1) (n `shiftL` 1) | otherwise = testBits (f `shiftR` 1) (n `shiftL` 1)
So, extractBitMasks needs fixing, probably in a similar way. Duncan