The final type of attributes are #[cfg] attributes. These attributes are incredibly powerful, enabling us to compile certain parts of the code depending on the target we are compiling to. For example, we might want to use a specific Windows function and have a backup one for the rest, or we might want the code to do different things in little- and big-endian machines.
The syntax is pretty easy. For example, if you want to check the system architecture, you can use #[cfg(target_arch = "arm")], and instead of ARM, you can check for "x86", "x86_64", "mips", "powerpc", "powerpc64", or "aarch64" too. To compile something only for FreeBSD, we can use #[cfg(target_os = "freebsd")]. You can compare the target_os configuration ...
