main.rs

extern crate othercrate = "othercrate#0.1.0";

use std::intrinsics::TypeId;

use othercrate::other::{Foo, foo_id};

fn main() {
	println!("Foo's TypeId from this crate: {}", TypeId::of::<Foo>());
	println!("Foo's TypeId from othercrate: {}", foo_id());
}

Makefile

.PHONY : all
all: thiscrate

.PHONY : thiscrate
thiscrate: libothercrate
	rustc -L . -O main.rs

.PHONY : libothercrate
libothercrate:
	rustc -O --crate-type=rlib --out-dir . othercrate/lib.rs

othercrate_lib.rs

#![crate_id = "othercrate#0.1.0"]
#![crate_type = "lib"]

pub mod other;

othercrate_other.rs

use std::intrinsics::TypeId;


pub enum Foo {
	VarA(uint),
	VarB(uint, uint)
}

pub fn foo_id() -> TypeId {
	TypeId::of::<Foo>()
}

Prints
Foo's TypeId from this crate: TypeId { t: 17870372292551777611 }
Foo's TypeId from othercrate: TypeId { t: 15921533803692407670 }