Can I mark a function as deprecated?

I'd like to mark functions/methods as deprecated. I tried to apply the deprecated attribute:

#[deprecated]
fn old_way_of_doing_it() {

but this yields an error:

error: stability attributes may not be used outside of the standard library

Is there a way in which I can have the compiler warn a consumer of my library that a function is deprecated?

I have no experience, but I'm considering experimenting with compiler plugins and custom attributes, but I guess that would require the consumer to also use the plugin, which is maybe unreasonable (or may be an unreasonable amount of work for me to implement?)

As a side question out of curiosity, why is the deprecated attribute only applicable to the standard library?

Since Rust 1.9.0 (2016 May 26th) you can use the #[deprecated] attribute in your own crates (RFC 1270). The syntax is:

#[deprecated(since="0.5.0", note="please use `new_method` instead")]
pub fn old_method() { ..; }

It will throw the following warning whenever you use old_method:

:6:5: 6:15 warning: use of deprecated item: please use `new_method` instead, #[warn(deprecated)] on by default
:6     old_method()
             ^~~~~~~~~~

You may find more information in the RFC.

Stack Overflow Q#30757914, score: 62