Flag logic in CMake is faulty

[zerothi]

One basically can't add flags on the command line in release mode since you overwrite everything.

Please don't overwrite CXX_FLAGS when users want to point to dependent libraries in other directories.

For instance:

CXXFLAGS="-I<some path>" cmake -DCMAKE_CXX_FLAGS="-I<some path>" -H. -Bbuild

will neglect all flags...

I would advice you to not mingle with the CMAKE_CXX_FLAGS, or at least always append stuff if you really want to.

Altogether I would suggest you avoid the hard-coding to some extent as it means one cannot build your project with other compilers than GNU.