Re: [Mingw-cross-env-list] Qt with Cmake

[Daniel Stonier]

On 25 November 2010 07:12, Mark Brand <address@hidden> wrote:
>
>
>>> Anyway, it's not clear to me why cmake would need to be told that the Qt
>>> libraries are static. It just needs to know the dependencies of the
>>> libraries used, and these should be in the .prl files. Obviously the .prl
>>> files will differ depending whether the libraries they describe are
>>> static
>>> or shared.
>>>
>>> Mark
>>
>> Sounds logical. I did some more testing just to closely see what was
>> getting linked and what was not and whether it was trying static or
>> dynamic linking. And it all looked correct. So I went back to setting
>> and unsetting -DQT_DLL making sure that QT_LIBRARIES was the same in
>> both situations. Without, it compiles fine, with it, it dies with
>> undefined references. The FindQt4.cmake files set this on by default
>> unless there's something in that global qconfig.pri file.
>
> I'm not sure if this is part of the issue, but don't forget that the Qt
> libraries have different names in Windows depending on whether they are
> static or shared.
>
>> So, it looks like windows does absolutely need to be told via QT_DLL
>> macro if qt was statically built or dynamically built - this affects
>> how the applications cpp files (aka my main.cpp) are built.
>>
>> 1) Should QT_DLL be set/not set using a decision better than looking
>> up qconfig.pri for 'static'? Can it be automatic?
>
> I think qmake must do that by considering the mkspec. It looks like
> mkspecs/features/qt.prf is responsible for QT_DLL.
>
>> 2) Parsing the prl's, if available, guarantee that you don't miss any
>> dependencies when statically compiling. Is it useful when dynamically
>> linking?
>>
>
> Don't forget that static and shared linking can be used together. For
> example, if you build shared Qt on mingw-cross-env where everything else is
> static, the shared Qt libs will have static dependencies that will have to
> be explicitly linked to your application. The .prl files can help with that.
>
> Mark

Good point. I'm talking with the guy who writes the cmake FindQt4
module and he's grabbed mingw_cross for some road testing. He's
avoiding the prl's for some reason though, not sure why. Anyway, good
news is that we should have better support for mingw_cross' qt next
version.

Regards,
Daniel.

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