Bug#667346: qtwebkit: ftbfs with GCC-4.7

[Matthias Klose <doko@debian.org>]

Package: qtwebkit
Version: 2.2.0-3
Severity: important
Tags: sid wheezy
User: debian-gcc@lists.debian.org
Usertags: ftbfs-gcc-4.7

The package fails to build in a test rebuild on at least amd64 with
gcc-4.7/g++-4.7, but succeeds to build with gcc-4.6/g++-4.6. The
severity of this report may be raised before the wheezy release.

../JavaScriptCore/wtf/RefCounted.h:141:13: error: deleting object of polymorphic class type 'WebCore::Frame' which has non-virtual destructor might cause undefined behaviour [-Werror=delete-non-virtual-dtor]

The full build log can be found at:
http://people.debian.org/~lucas/logs/2012/03/29-clang-gcc47/unstable-gcc47/qtwebkit_2.2.0-3_unstable-gcc47.log
The last lines of the build log are at the end of this report.

Some hints on fixing these issues can be found at
http://gcc.gnu.org/gcc-4.7/porting_to.html

To build with GCC 4.7, either set CC=gcc-4.7 CXX=g++-4.7 explicitly,
or install the gcc, g++, gfortran, ... packages from experimental.

[...]
In file included from ../JavaScriptCore/wtf/CrossThreadRefCounted.h:36:0,
                 from ../JavaScriptCore/wtf/text/StringImpl.h:28,
                 from ../JavaScriptCore/wtf/text/AtomicStringImpl.h:24,
                 from ../JavaScriptCore/wtf/text/AtomicString.h:24,
                 from ../JavaScriptCore/wtf/text/StringHash.h:25,
                 from platform/ThreadGlobalData.h:33,
                 from dom/EventNames.h:25,
                 from dom/EventTarget.h:35,
                 from dom/Node.h:28,
                 from editing/VisiblePosition.h:30,
                 from accessibility/AccessibilityObject.h:34,
                 from accessibility/AccessibilityRenderObject.h:33,
                 from accessibility/AccessibilityRenderObject.cpp:30:
../JavaScriptCore/wtf/RefCounted.h: In instantiation of 'void WTF::RefCounted<T>::deref() [with T = WebCore::Frame]':
../JavaScriptCore/wtf/PassRefPtr.h:59:13:   required from 'void WTF::derefIfNotNull(T*) [with T = WebCore::Frame]'
../JavaScriptCore/wtf/RefPtr.h:58:35:   required from 'WTF::RefPtr<T>::~RefPtr() [with T = WebCore::Frame]'
page/FrameTree.h:37:29:   required from here
../JavaScriptCore/wtf/RefCounted.h:141:13: error: deleting object of polymorphic class type 'WebCore::Frame' which has non-virtual destructor might cause undefined behaviour [-Werror=delete-non-virtual-dtor]
cc1plus: all warnings being treated as errors
make[3]: *** [obj/release/AccessibilityScrollView.o] Error 1
cc1plus: all warnings being treated as errors
make[3]: *** [obj/release/AccessibilityRenderObject.o] Error 1
make[3]: Leaving directory `/«PKGBUILDDIR»/Source/WebCore'
make[2]: *** [sub-WebCore-make_default-ordered] Error 2
make[2]: Leaving directory `/«PKGBUILDDIR»/Source'
dh_auto_build: make -j10 returned exit code 2
make[1]: *** [override_dh_auto_build] Error 2
make[1]: Leaving directory `/«PKGBUILDDIR»'
make: *** [build-arch] Error 2
dpkg-buildpackage: error: debian/rules build-arch gave error exit status 2