useInitializationList
ftp://ftp.de.debian.org/debian/pool/main/c/cxxopts/cxxopts_3.3.1.orig.tar.gz
head jarro2783-cxxopts-44380e5/test/catch.hpp:9319:13: performance: Variable 'm_ref' is assigned in constructor body. Consider performing initialization in initialization list. [useInitializationList]