How to use a local unpublished crate?

I've made a library:

cargo new my_lib

and I want to use that library in a different program:

cargo new my_program --bin

extern crate my_lib;

fn main {
    println!("Hello, World!");
}

what do I need to do to get this to work?

They aren't in the same project folder.

.
├── my_lib
└── my_program

Hopefully this makes sense.

I thought I'd be able to override the path as per the Cargo guide, but it states

You cannot use this feature to tell Cargo how to find local unpublished crates.

This is when using the latest stable version of Rust (1.3).

Solution 1:

Add a dependency section to your executable's Cargo.toml and specify the path:

[dependencies.my_lib]
path = "../my_lib"

or the equivalent alternate TOML:

[dependencies]
my_lib = { path = "../my_lib" }

Check out the Cargo docs for specifying dependencies for more detail, like how to use a git repository instead of a local path.