[Haskell-cafe] building HSQL MySQL on windows (Was: FFI imported function names)

Daniil Elovkov daniil.elovkov at googlemail.com
Wed Dec 24 14:01:26 EST 2008

Ok, enough talking to myself :)

If anybody ever wants to build hsql-mysql on windows and has the same
problems as I had, here's how it should be done.

The problem I had seemed to be that libmysql.dll uses stdcall, but
names its functions without @<n> decoration. Thus, when linking a
Haskell program against it, names with @<n> cannot be resolved.

The solution is pretty much a hack. Somebody from the Ruby community
used to run into the same problem, from the same situation -- namely
building ruby mysql bindings.

Here is the procedure one person suggests

It worked perfectly for me. Of course, with some cabal specifics,
which is obviously not described in the above page.

The solution was to create a def file listing the names which could
not be resolved and creating a .a file based on the dll and this def

2008/12/24 Daniil Elovkov <daniil.elovkov at googlemail.com>:
> Mm, actually I didn't change the calling convention ffi imports when I
> thought I did. I tried to do it through defines...
> Well, by explicitly saying ccall I get the names without @<n>
> decoration. And it all links well. But I get segault when I run the
> code, which should mean that calling conventions didn't match.
> Actually I found some ramblings on the internet that there's something
> wrong with libmysql.dll and libmysql.lib in this respect, but they
> were from 2004.
> Thus the question: how do I link against a lib file in ghc? When I say
> -lmysql on command line it strictly searches for dll and complains if
> it's not found. Adding lib exlpicitly on the cmd line doesn't seem to
> have any effect.
> Thanks
> 2008/12/24 Daniil Elovkov <daniil.elovkov at googlemail.com>:
>> Hello
>> How is decided whether the name of imported function gets the ending
>> of the form @4 in ghc?
>> I'm having this problem on Windows trying to use HSQL MySQL on windows.
>> I compile HSQL Oracle backend and I get names without that. It's ok.
>> With HSQL MySQL I get names with that stuff. It prevents me from
>> further linking to dll. Supplying in the ghc command-line the "lib"
>> file where names have those marks doesn't have any effect.
>> The linker says that fname at NN cannot be resolved.
>> Can I control that?
>> The ffi calling convention doesn't (and shouldn't as I understand)
>> affect this. The only difference is that in the case of mysql the
>> header file itself where functions are described marks it STDCALL. Is
>> that the reason?
>> Also I changed ffi import line from "hsmysql.h func" to just "func",
>> to no avail.
>> ghc 6.8.2
>> I'm lost. Please help.
>> --
>> Daniil Elovkov
> --
> Daniil Elovkov

Daniil Elovkov

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