[Haskell-cafe] Re: FFI question

[Frederico Franzosi]

Thank you Simon...
That was just what I needed...
Short and simple.

I would like also to thank all for the answers. That will be surely
helpful too, if not for me, maybe for someone else.

On 2/9/06, Simon Marlow <simonmarhaskell at gmail.com> wrote:
> Frederico Franzosi wrote:
> > I'll try to make it short.
> >
> > I'm developping a package wich imports C functions.
> >
> > the fact is that when I try to compile if I call the compiler in the
> > usual way, using -package and -llib it gives an undefined reference
> > error...
> >
> > For example if I use:
> > $ghc -package PKGname-PKGversion -fffi -o main Main.hs -llib
> >
> > it gives an error message (undefined references of objects from PKG to
> > functions in lib)
> >
> >
> > but if I use:
> >
> > $ghc -fffi -o main Main.hs -llib /path/to/PKGlib.a
> >
> > it compiles correctly.
>
> It looks like -llib is appearing earlier on the linker's command line
> than the library from your package, when you use -package.  You haven't
> specified a dependency between the two, so GHC is making an arbitrary
> choice.
>
> The right way to fix this, if your package depends on a library, is to
> include that library in the "extra-libraries" field of the package.
>
> Cheers,
>         SImon
>