Enabling Link time optimization for GCC (MinGW64) removes resources from exe

Found this little thing today.

Adding the following optimization flags to .pro file will remove resources from compiled .exe file:

QMAKE_CXXFLAGS += -flto
QMAKE_LFLAGS += -fuse-linker-plugin -flto

If my memory works correctly, this optimization still worked with Qt 5.2.1 mingw bundle, but that must have had an older gcc version??

So is this a compiler bug or Qt bug ?

How to reproduce:

• Compile and run the attached test project. Small adobe pdf icon should not be shown on the button.

• Now, comment out the above to environment flags from .pro file, clean the project, recompile & run. adobe pdf icon should appear on the button.