`extern crate proc_macro` not found even if the project compiles

[KizzyCode]

The Rust-plugin gives me the error extern crate proc_macro not found even if the project compiles without an error.

Cargo.toml:

[package]
name = "json_derive"
version = "0.1.0"
authors = ["Keziah Biermann <development@kizzycode.de>"]

[lib]
proc-macro = true

[dependencies]
syn = "0.15.14"
quote = "0.6.8"

lib.rs:

#![recursion_limit = "128"]

extern crate proc_macro; // ← This gives me the "not found" error
extern crate syn;
#[macro_use] extern crate quote;

use proc_macro::TokenStream;


#[proc_macro_derive(Dummy)] pub fn dummy_derive(input: TokenStream) -> TokenStream {
	unimplemented!()
}

[Undin]

@KizzyCode this repo is not about IntelliJ Rust plugin, just about intellij-rust.github.io page
Please, file issue related to the plugin here
Also, it's a duplicate of intellij-rust/intellij-rust#2623

[KizzyCode]

Ups, sorry 😕