Speaking about C and C++ on Linux, I have an impression that the compilers seldom can decide that the whole functions aren't used, especially because most libra

Speaking about C and C++ on Linux, I have an impression that the compilers seldom can decide that the whole functions aren't used, especially because most libraries and programs "export" "everything" by default, so only on run-time it can be decided what will be actually used -- the last linking step happens only when you start the program, by the loader.