patches/proc_macro.patch

diff --git a/src/lib.rs b/src/lib.rs
index 2f31fc6..d1fe77e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,6 +3,7 @@
 #![crate_type = "proc-macro"]
 #![forbid(unsafe_code)]
 #![warn(rust_2018_idioms, trivial_casts, unused_qualifications)]
+extern crate proc_macro;
 
 use proc_macro2::{Ident, TokenStream};
 use quote::{format_ident, quote};