1diff --git a/src/lib.rs b/src/lib.rs 2index 2f31fc6..d1fe77e 100644 3--- a/src/lib.rs 4+++ b/src/lib.rs 5@@ -3,6 +3,7 @@ 6 #![crate_type = "proc-macro"] 7 #![forbid(unsafe_code)] 8 #![warn(rust_2018_idioms, trivial_casts, unused_qualifications)] 9+extern crate proc_macro; 10 11 use proc_macro2::{Ident, TokenStream}; 12 use quote::{format_ident, quote}; 13