good bug! -O or -O2 is irrelevant but it works if compiled with -fvia-C
You (or someone else) should add it to
http://hackage.haskell.org/trac/ghc
Christian
Brad Clow wrote:
I upgraded from GHC 6.6.1 to 6.8.1 and around that time I noticed that
the output from an app I am working on changed. I have distilled the
code down to the following example that produces different output
depending on whether it is compiled with -O2 or not:
main = do
let (T x) = read T 3
print $ f x
print $ g x
data T = T Int deriving (Read, Show)
f x = truncate $ 2000 / fromIntegral ((x * 25) + 10)
g :: Int - Int
g x = f x
Here is the transcript from a shell (example code is saved in test.hs):
$ ghc --make test.hs
[1 of 1] Compiling Main ( test.hs, test.o )
Linking test ...
$ ./test
23
23
$ rm test.hi test.o test
$ ghc -O2 --make test.hs
[1 of 1] Compiling Main ( test.hs, test.o )
Linking test ...
$ ./test
23
24
It is a little disconcerting that -O2 changes the output. :-)
Regards
brad
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