CMake cxx_std_* propagation

[Wile_E_Coyote]

Compiler flag errors

Your source code may be “sensitive” to the “ROOT_CXX_FLAGS” and “ROOT_CXX_STANDARD” variables (which come from ROOT). The problem is that you may have (note “undefined”): ROOT_CXX_FLAGS -std=c++17 -pipe -fsigned-char -pthread ROOT_CXX_STANDARD undefined or (note the missing “-std=c++17”): ROOT_CXX_FLAGS -pipe -fsigned-char -pthread ROOT_CXX_STANDARD 17 Try the simple “CMakeLists.txt” file from (just execute “cmake .”):