Bug 822710

Description of problem:
When trying to build a 32bit binary for a Qt based program on 64bit CFLAGS will always include -m64 for release configuration.

Version-Release number of selected component (if applicable):
$ rpm -q qt-devel
qt-devel-4.8.1-5.fc16.x86_64
qt-devel-4.8.1-5.fc16.i686
$ uname -a
Linux luna.lan 3.3.5-2.fc16.x86_64 #1 SMP Tue May 8 11:24:50 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
$ cat /etc/fedora-release 
Fedora release 16 (Verne)


How reproducible:
Always reproducible with -spec linug-g++-32 for release binary, not reproducible for debug binary (-spec linux-g++-32 -config debug).


Steps to Reproduce:
Build an arbitrary Qt based program (example below taken from http://doc.qt.nokia.com/4.7/gettingstartedqt.html) using -spec linux-g++-32:
$ cat << EOF > test.cpp
> #include <QApplication>
> #include <QTextEdit>
> 
> int main(int argv, char **args)
> {
>     QApplication app(argv, args);
> 
>     QTextEdit textEdit;
>     textEdit.show();
> 
>     return app.exec();
> }
> EOF
$ qmake-qt4 -project
$ qmake-qt4 -spec linux-g++-32
$ make
g++ -c -m32 -pipe -O2 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/lib64/qt4/mkspecs/linux-g++-32 -I. -I/usr/include/QtCore -I/usr/include/QtGui -I/usr/include -I. -I. -o test.o test.cpp
g++ -m32 -Wl,-O1 -o a test.o    -L/usr/lib64 -lQtGui -lQtCore -lpthread 
/usr/bin/ld: skipping incompatible /usr/lib64/libQtGui.so when searching for -lQtGui
/usr/bin/ld: skipping incompatible /usr/lib64/libQtCore.so when searching for -lQtCore
/usr/bin/ld: skipping incompatible /usr/lib64/libpthread.so when searching for -lpthread
/usr/bin/ld: skipping incompatible /usr/lib64/libm.so when searching for -lm
/usr/bin/ld: skipping incompatible /usr/lib64/libc.so when searching for -lc
/usr/bin/ld: i386:x86-64 architecture of input file `test.o' is incompatible with i386 output
collect2: ld returned 1 exit status
make: *** [a] Error 1

This problem does not appear if you build as debug binary:
$ qmake-qt4 -spec linux-g++-32 -config debug
$ make
g++ -c -m32 -pipe -g -Wall -W -D_REENTRANT -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/lib64/qt4/mkspecs/linux-g++-32 -I. -I/usr/include/QtCore -I/usr/include/QtGui -I/usr/include -I. -I. -o test.o test.cpp
g++ -m32 -o a test.o    -L/usr/lib64 -lQtGui -lQtCore -lpthread 
/usr/bin/ld: skipping incompatible /usr/lib64/libQtGui.so when searching for -lQtGui
/usr/bin/ld: skipping incompatible /usr/lib64/libQtCore.so when searching for -lQtCore
/usr/bin/ld: skipping incompatible /usr/lib64/libpthread.so when searching for -lpthread
/usr/bin/ld: skipping incompatible /usr/lib64/libm.so when searching for -lm
/usr/bin/ld: skipping incompatible /usr/lib64/libc.so when searching for -lc
{ test -n "" && DESTDIR="" || DESTDIR=.; } && test $(gdb --version | sed -e 's,[^0-9]\+\([0-9]\)\.\([0-9]\).*,\1\2,;q') -gt 72 && gdb --nx --batch --quiet -ex 'set confirm off' -ex "save gdb-index $DESTDIR" -ex quit 'a' && test -f a.gdb-index && objcopy --add-section '.gdb_index=a.gdb-index' --set-section-flags '.gdb_index=readonly' 'a' 'a' && rm -f a.gdb-index || true
$ ldd a
(bunch of 32bit libs)

  
Actual results:
Compiler flags contain -m64 additionally and after -m32, resulting in 64bit objects.


Expected results:
Compiler flags contain -m32 only, resulting in 32bit objects.


Additional info:
The problem is caused by the mkspec gcc-base.conf, which adds the -m64 parameter to QMAKE_CFLAGS_RELEASE. When removing the -m64 things work as expected. This also explains why the problem doesn't appear if -config debug is used.