Use flag '-Wdouble-promotion' only on version 4.6 or greater of g++
Use flag '-Wdouble-promotion' only on version 4.6 or greater of g++

Older version does not support this flag.
To find the version of g++, I use the trick from KDEs MacroEnsureVersion.cmake file

aevum/libgdx-cpp,aevum/libgdx-cpp,aevum/libgdx-cpp,aevum/libgdx-cpp