Rust raw identifiers

Overview

Raw identifiers allow us to give a variable/function/… a name that is a reserved word.

For instance, the following snippet will not compile

struct Foo {
    name: String,
    type: String,
}

whereas this one will

struct Foo {
    name: String,
    r#type: String,
}

This is particularly useful when wanting to refer to a function in a crate of a previous rust edition that allowed the function to be named to something that is a reserved word in newer rust editions.

For example, assuming crate foo is using 2015 edition and the snippers below are using 2018 edition when try became a reserved word we have:

extern crate foo;

fn main() {
    foo::try();
}

You’ll get this error:

error: expected identifier, found keyword `try`
--> src/main.rs:4:4
|
4 | foo::try();
|      ^^^ expected identifier, found keyword
You can write this with a raw identifier:

This will compile though:

extern crate foo;

fn main() {
    foo::r#try();
}

References

• https://doc.rust-lang.org/rust-by-example/compatibility/raw_identifiers.html