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

[Daniil Elovkov]

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
http://rubydotnetproxy.rubyforge.org/mysql_win.html

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
file.


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