Do you seriously think that's how IP law works? If you weren't able to write GPL Rust code, Rust would not be free software. That would require the Rust project to issue software licences to programmers that stipulate that you must not create GPL-licensed software using Rust.
Rust is free and open-source, like most programming languages. That means you are allowed to make whatever software you want with it, including GPL software. There's nothing stipulating that you can't...