Revisiting gcc versions, decided to use the official documentation for reference: First versions documenting support for the features, only goes back to 2.95. unused: https://gcc.gnu.org/onlinedocs/gcc-2.95.3/gcc_4.html#SEC90 deprecated: https://gcc.gnu.org/onlinedocs/gcc-3.1.1/gcc/Function-Attributes.html deprecated with message: https://gcc.gnu.org/onlinedocs/gcc-4.5.4/gcc/Function-Attributes.html