$ cat smallhello.c
#include <unistd.h>
int main()
{
char hello[] = "hello, world\n";
write(1, hello, sizeof hello - 1);
return 0;
}
$ diet gcc -Wl,-z,noseparate-code smallhello.c -o smallhello
$ strip smallhello
$ ls -l smallhello
-rwxr-xr-x 1 user user 4864 Feb 9 06:47 smallhello
$ ./smallhello
hello, world
i would argue that this is 'with no linker optimizations' because -z noseparate-code was the default until a few years ago. linker optimizations can save another 200 bytes or so in this case
note that this is without dynamic linking. there's no giant standard library being swept under the rug here. most of the executable code in the resulting program is _start pulling in stackgap, which calls find_in_auxvec, __libc_open, __libc_read, __libc_close, __setup_tls, getenv, strstr, and finally main, and strstr in turn calls memcmp (as does getenv) and strlen. main() itself is only 61 bytes of code, __libc_write is 6 bytes, mostly a tail call to __unified_syscall, which is 34 bytes. so we're already looking at overhead that's 40 times the size of the hello-world code itself, which rust apparently expands to 100 times?
but possibly not; it's easy to accidentally compile something with c that ends up 14 kilobytes too
but basically c's required runtime is just memset() and memcpy(). everything else only gets invoked if you call it explicitly
> but basically c's required runtime is just memset() and memcpy(). everything else only gets invoked if you call it explicitly
Rust is barely more: https://doc.rust-lang.org/stable/core/
> memcpy, memmove, memset, memcmp, bcmp, strlen
> rust_begin_panic
> rust_eh_personality
Take a look at "#![no_std]", a Rust feature.
If you do that, your Rust Hello World program will have 14 kiB (with no linker optimizations).
>and allows formal verification (including functional requirements)
See <https://rust-formal-methods.github.io/tools.html>.
Also, the Rust compiler can be used as a library and you can add whatever checks you want like that. See <https://yoric.github.io/post/uom.rs/> for an example (not used that much).
Also, I like <https://docs.rs/pre/latest/pre/attr.pre.html>. It allows you to define and then mandate specifying textual requirements (in addition to the usual conditionals).