Hi. I have two packages. The first one is a lib that uses bindings for native C libary.

unsafe extern "C" {
    fn add(a: i32, b: i32) -> i32;
}

pub fn safe_add(a: i32, b: i32) -> i32 {
    unsafe { add(a, b) }
}

and the second one is exe that depends on this lib:

fn main() {
    let result = rust_lib::safe_add(2, 3);
    println!("The result of adding 2 and 3 is: {}", result);
}

I don't understand a few things:

1. Why does the lib compile without any build.rs scripts with cargo build? It looks like the compiler doesn't check that the add function exists somewhere.
2. The exe compiles only if I add these build scripts:

// lib package
fn main() {
    println!("cargo::rustc-link-lib=add");
}

// exe package
fn main() {
    println!("cargo::rustc-link-search=native=<path/to/native/lib>");
 
}

Why does it work like this? I don't understand why I don't need to specify the library path in the lib's build script and the library name in the exe's build script. Do these build scripts depend on each other?

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