ktoon version 0.8.1-4.1ubuntu2 failed to build on amd64 with GCC-4.6/oneiric

ktoon version 0.8.1-4.1ubuntu2 failed to build on amd64 with GCC-4.6/oneiric
Link to failed build: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2454763

Details about the rebuild:
https://lists.ubuntu.com/archives/ubuntu-devel/2011-April/033042.html

Direct link to the build log: https://launchpad.net/ubuntu/+archive/test-rebuild-20110413/+buildjob/2454763/+files/buildlog_ubuntu-natty-amd64.ktoon_0.8.1-4.1ubuntu2_FAILEDTOBUILD.txt.gz

This log snippet might be of interest, since it triggered the matcher 'Purging chroot-autobuild'.
Excerpt 1415 lines into the build log:

ktdualcolorbutton.cpp: At global scope:
ktdualcolorbutton.cpp:171:6: warning: unused parameter 'ev' [-Wunused-parameter]
ktdualcolorbutton.cpp:176:6: warning: unused parameter 'ev' [-Wunused-parameter]
ktdualcolorbutton.cpp:242:6: warning: unused parameter 'ev' [-Wunused-parameter]
ktdualcolorbutton.cpp:259:6: warning: unused parameter 'ev' [-Wunused-parameter]
make[4]: *** [.obj/ktdualcolorbutton.o] Error 1
make[4]: Leaving directory `/build/buildd/ktoon-0.8.1/src/components/colorpalette'
make[3]: *** [sub-colorpalette-make_default] Error 2
make[3]: Leaving directory `/build/buildd/ktoon-0.8.1/src/components'
make[2]: *** [sub-components-make_default] Error 2
make[2]: Leaving directory `/build/buildd/ktoon-0.8.1/src'
make[1]: *** [sub-src-make_default] Error 2
make[1]: Leaving directory `/build/buildd/ktoon-0.8.1'
make: *** [build-stamp] Error 2
dpkg-buildpackage: error: debian/rules build gave error exit status 2
******************************************************************************
Build finished at 20110423-2325
FAILED [dpkg-buildpackage died]
Purging chroot-autobuild/build/buildd/ktoon-0.8.1