Qt Creator + Qt 4.7.3 on Mac OS 10.6 - always builds x86_64, but I need 32 bit.
I’m compiling my Qt app on Mac OS 10.6.8 with the latest Qt Creator (2.2.1) and Qt 4.7.3 installed from the Online Installer.
When I compile my app that uses some 3rd party libraries built for x86 and PPC in Qt Creator, I get “missing required architecture x86_64 in file….” errors. So obviously it is compiling for 64 bits – which I don’t need.
In my .pro file I have:
Which I understand will tell the compiler to not build for 64 bits.
When I look at the “Build Settings” for my project I notice:
“Qt version” is “Desktop Qt 4.7.3 for GCC (Qt SDK)” and is grayed out.
“Tool chain” is “GCC (x86 64bit)” and also grayed out.
I’m not sure why only 64 bit compiles are available. Should I be able to select to use 32 bits in the “Build Settings”?
Also shouldn’t my settings in the .pro file remove the 64 bit build, and add x86 32 bit and PCC?
I don’t remember seeing any options during the Qt install to select the defaults.
How can I tell Qt Creator to only build for 32 bit x86 and PPC?
I won’t say for sure, especially since I don’t use Mac OS, but probably the libraries you link against are 64bit (that’s the case in Linux anyway). So, in order to compile x86, you’ll have to compile Qt in x86, or use the source files instead of the lib. Mind you, I might be wrong, I myself am happy with x86_64, and have not actually tried compiling for other architectures. Also, this might be some special case of Mac that I’m not aware of.
The Qt version being greyed out shows that you only have that one available for the target you develop for. So the first thing is which ABIs does it support? Please check in Tools->Options->Qt versions and hover the Qt version in question. Check the tooltip for information on the supported ABIs. If there is no 32bit version there, then you will need to install a Qt that actually was compiled for a 32bit environment.
If that lists 32bit, then you might not be able to build a 32bit version because Qt Creator did not find any 32bit tool chain on your system: Please check in Tools->Options->Tool chains and make sure you have tool chains defined for all ABIs of the Qt version.
I’m using Qt from the online installer for Mac OS.
The Qt version tool tip shows:
On the Tool Chains panel it shows:
GCC (x86 64bit) GCC
GCC (x86 32bit) GCC
GCC (ppc 64bit) GCC
GCC (ppc 32bit) GCC
So it looks like it has 32 bits in the tool chain – correct?
Then why does it compile and link against 64 bit stuff? I get errors because some of the Carbon APIs I use aren’t available in 64 bit. If I remove those temporarily, when it gets to linking it says that my external frameworks are missing 64bit architecture (which I know – but I don’t want a 64 bit app anyway).
Here is some output from the compile window, which seems to prove the compiler is being directed to make a 64 bit version:
g++ -c -pipe -O2 -arch x86_64 -Xarch_x86_64 -mmacosx-version-min=10.5 -arch ppc -arch i386 -Wall -W -isysroot /Developer/SDKs/MacOSX10.5.sdk -DNDEBUG -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I../../../QtSDK/Desktop/Qt/473/gcc/mkspecs/macx-g++ -I../
I see there are multiple -arch parameters there. So where are the “-arch x86_64 -Xarch_x86_64” coming from? In my pro file I have :
CONFIG -= x86_64
CONFIG +=x86 ppc
I’ve also tried with just:
CONFIG +=x86 ppc
Looks like we are having trouble to pick the correct mkspec. As a workaround you can specify the mkspec you want via the qmake build step widget (Projects->Build Settings, somewhere in the middle of the page). I am not sure there actually is one available to build for 32bit PPC on Mac though.
Please file a bug report [bugreports.qt.nokia.com] if you find one:-)
OK I filed a bug report:
Sorry but I’m not quite sure how I would specify the mkspec to not tell the compiler to use “-arch x86_64 -Xarch_x86_64”.
FYI – I have Xcode 3.2.6 installed and it will compile my app OK as 32 bit only when creating an XCode project from the .pro file.
That didn’t work. I did a clean and rebuild of my app but I still see “-arch x86_64 -Xarch_x86_64” in the compile output. It’s like it is totally ignoring it.
The following may be useful:
If in Qt Creator I go to the Build Settings, General and change the “Qt Version” from “Desktop Qt 4.7.3 for CGG (SDK)” to “Qt in PATH”, then do a clean rebuild of my app I no longer get any of the x64 stuff included.
Does that mean something is messed up with my Qt install?
I don’t know for sure, I never installed Qt from the SDK, but it may be that the SDK only delivers universal binaries containing intel code and/or containing only 64bit code. You can check yourself with
The output will containt i386 and ppc7400 for Intel and PPC 32bit, and x86_64 for Intel 64bit.
Also, make sure that the command line for qmake in the build settings pane, does not contain any arch related stuff, as this can override the settings in the .pro file.
I just stumbled across this problem myself, though I don’t fully understand it.
I’m running Creator 2.3.0, based on Qt 4.7.4 (64 bit).
So, do I understand correctly that I can’t control which GCC the build process uses? In Preferences -> Tool Chains, I have Auto-detected entries for both 64 and 32 bit (as well as some PPC entries which I should probably get rid of). 64 is listed first, so I assumed that’s why I was getting 64-bit integers in my code. Not so?
The toolchain on the Mac is a single one (although Creatore reports at least two). You have only one gcc (per version, you have gcc-4.0 and gcc-4.2 of course). This gcc can produce object code for Intel and PowerPC and for 32 and 64 bit, make four architectures altogether.
BUT: You cannot create an object file containing, let’s say 32 and 64 bit Intel code, in case your Qt libs only contains 64 bit Intel code. In the end, the linker would complain that some code is missing.
I never used the prebuilt binaries or SDKs for the Mac myself, so I cannot tell you what’s inside. You can find out yourself:
It should print something like: Architectures in the fat file: /usr/local/Trolltech/Qt-4.7.3/lib/QtGui.framework/QtGui are: i386 ppc7400 – the architectures listed differ, of course :-)
By manipulating the CONFIG variable you control for which architectures code will be built.