Re: [Mingw-cross-env-list] MXE, Shared QT builds, and Freetype

[Mark Brand]

Jeremy Salwen wrote:
> Hi all,
>
> I'm looking to build a shared version of QT based on the MXE setup.  
> I've actually made quite a bit of progress, and I've been able to 
> convert all of the required packages for qtbase into shared builds 
> that compile and install correctly. If I get it working, I'll put the 
> changes up on github.

This topic has come up from time to time on the mailing list. You might 
want to search the archives for previous discussions.

> However, when I try to compile a shared build of qtbase, I get errors 
> resolving symbols in libfreetype (see the attached build log).  From 
> what I can tell, qt is simply forgetting to add the flag -lfreetype 
> when compiling qwindows.dll , as qbasicfontdatabase.cpp (which 
> compiles into qwindows.ll) uses functions defined in libfreetype. 
> Unfortunately, the ./configure script seems to be oblivious of any 
> options involving freetype, and greets -no-freeetype -system-freetype, 
> and -qt-freetype with the same "invalid command-line switch".
>
> When I asked in the QT IRC channel, I was questioned why I was 
> building QT on windows with freetype, which I'm not sure about.  Why 
> does MXE build QT with freetype?
First some background:
MXE uses qtbase's configure script, rather than configure.exe which is 
specifically for Windows. The configure script lacks the 'freetype' 
options that configure.exe has. The configure script uses the "system" 
freetype library if found. In our case, it is found in the MXE "system". 
The configure script also needs to find fontconfig before finding 
freetype. As far as I can tell, fontconfig isn't even used for Windows, 
but we have fontconfig as a fake dependency just to make this work.

Your main question is why -lfreetype is missing when linking 
qwindows.dll in a shared Qt build with "system-freetype". I think the 
problem is an upstream problem. It looks to me like -freetype is not 
added by the Qt build system except in combination with fontconfig.

MXE has a patch for qtbase to use pkgconfig for freetype. This fixed the 
problem for our static builds, but as you've discovered, not for shared 
ones. I see now that the change can be applied in a better place that 
works for both. Please try it out. The change is in commit 2d29cafd2df.

Alternatively, you could build without "system freetype", maybe by not 
building it in MXE so configure won't detect it. I'm not sure if that 
will give you "no freetype" or "qt (bundled) freetype". Otherwise, you 
could add the explicit freeype options to the configure script that 
configure.exe has. Maybe that would be a good contribution for upstream.

Mark