Alberto, SevenThunders, Joel, Glark. This is not good. Thank you for being so polite about it. And thanks for working on a reproducible test case -- without that we are 100% stuck. We did fix one just-possibly-related bug in 6.8 recently, which concerned the use of {-# UNPACK #-} on strict Double-sized fields in fixed, top-level data structures. I think it was only wrong on a 64-bit machine. http://www.haskell.org/pipermail/glasgow-haskell-users/2007-November/013454.... What is the word size on your machine? But that may well be a complete red herring. We'll stand by. Simon | -----Original Message----- | From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Alberto Ruiz | Sent: 15 November 2007 08:44 | To: haskell-cafe@haskell.org | Subject: Re: [Haskell-cafe] ghc 6.8.1 bug? | | Hello, | | I have had exactly the same problem with my bindings to GSL, BLAS and LAPACK. | The foreign functions (!) randomly (but very frequently) produced NaN with | ghc-6.8.1 -O. As usual, I first thought that I had a subtle bug related to | the foreign pointers, but after a lot of refactoring, experiments, and | tracing everything, I'm reasonably sure that memory is safely used. What I | have found is that the same errors can be reproduced on ghc-6.6.1 | with -O -fasm. So I tried -O -fvia-C on ghc-6.8.1 (which now it is not the | default) and apparently everything works well. So it seems that now the ffi | requires and additional and explicit -fvia-C. In any case I don't know | why -fasm produces those strange NaN in precompiled foreign functions... | | Alberto | | On Thursday 15 November 2007 09:05, SevenThunders wrote: | > The good news is that my code compiles without error and much faster under | > ghc 6.8.1. | > The bad news is that there appear to be subtle bugs that did not occur when | > I compiled things under | > 6.6.1. One issue is that my code is somewhat complex and links into a C | > library as well.