[Interest] Building 32-bit Qt 5 on Mac

[morten.sorvig at nokia.com]

On Apr 24, 2012, at 6:38 PM, ext Thiago Macieira wrote:

On terça-feira, 24 de abril de 2012 11.41.14, Stephen Chu wrote:
So I grabbed Qt 5 from git to give it a shot again. I am now more
confused then before. :)

The configure script uses pre-processor output from
qtbase/config.tets/arch/arch.cpp to determine the host and target
architectures (around line 3707). I assume this is to setup compiler
flags for various features (SSE2, etc).

It then check the architecture that qmake is built in and adds it to
QT_CONFIG (line 4968). This makes the built libs in the same
architecture as qmake.

I guess I need to make/hack/trick the 2 the same to have a chance to
make it work? The former is using i386 while the later wants x86. So I
can't just copy them.

I don't think I am capable of coming up with a elegant solution. The
only way I can do it is to just hard code the architectures into the
configure script and hope for the best. :(

I think this discussion should be moved to development at qt-project.org<mailto:development at qt-project.org>. Cross-
posting now. Please drop interest at qt-project.org<mailto:interest at qt-project.org> when replying.

Like we've said before, you need to make the compiler flags such that it
produces a non-universal build of one single architecture: x86. Then the arch-
detection should work correctly.

Unless you're saying that the arch-detection is broken. Well, it is in one
way, I'm fixing it, but I don't think it's related to your problem.


Disregarding Thiago and cross-posting (sorry!)

Yes, Qt 5.0 will support 32-bit builds. We'll have to figure out _how_. I'm not a big fan of multiple mkspecs so I'm going to suggest a configure option of some sort. Perhaps we can re-use "-device-option" from http://labs.qt.nokia.com/2012/04/13/cross-compiling-qt-for-the-masses/ .

The only reason for supporting 32-bit builds is as far as I can see the need to integrate with other 32-bit software. This is a very good and sufficient reason. Qt 5 requires Mac OS 10.6 minimum, which requires a 64-bit capable CPU (Core 2 Duo). Universal binary support is not needed since you can reach all of the supported install base with a single 32 or 64 bit executable.

- Morten

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