Compiling 10MB+ resource files with qrc in cmake results in heap space allocation failures

If you are use the the build in cmake macros, just replace

qt5_add_resources(SRC_FILES resources.qrc) # normal resources

with

qt5_add_big_resources(SRC_FILES resources.qrc) # big resources

This requires Qt5.12 and CMake 3.9.

I've filed bug report QTBUG-55680 and will update this answer once I hear back from Qt.