Using Rust without the Standard Library

Rust is foremost a systems programming language and because the compiler can decide when a variable's lifetime ends, no garbage collection is needed for freeing memory. So when a Rust program executes, it runs in a very lightweight runtime, providing a heap, backtraces, stack guards, unwinding of the call stack when a panic occurs, and dynamic dispatching of methods on trait objects. Also, a small amount of initialization code is run before an executable project's main function starts up.

As we have seen, the standard library gives a lot of functionality. It offers support for various features of its host system: threads, networking, heap allocation, and more. It also links to its C equivalent, which also does some runtime initialization.

But Rust can also run on much more constrained systems that do not need (or do not have) this functionality. You can leave out the standard library from the compilation altogether by using the #![no_std] attribute at...