The binary size difference is presumably because the 'test' binary omits the version and help text, along with the code to display it. But if you look at the relevant Coreutils test.c code, the relevant code isn't disabled with an #ifdef. Instead, LBRACKET is #defined to 0 when compiling the 'test' binary. So it seems that modern C compilers are doing dead code elimination on the 'if (LBRACKET) { ...}' section, which is a well established optimization, and then going on to notice that the called functions like 'usage()' are never invoked and dropping them from the binary.