1Cargo automatically imports proc_macro in Rust 2018, but Soong only
2does this for rust_proc_macro targets.
3
4--- a/src/lib.rs	2023-11-06 16:32:46.480193187 +0100
5+++ b/src/lib.rs	2023-11-06 16:29:38.743132168 +0100
6@@ -34,6 +34,8 @@
7 use crate::mock_item_struct::MockItemStruct;
8 use crate::mockable_item::MockableItem;
9
10+extern crate proc_macro;
11+
12 // Define deterministic aliases for these common types.
13 type HashMap<K, V> = std::collections::HashMap<K, V, BuildHasherDefault<std::collections::hash_map::DefaultHasher>>;
14 type HashSet<K> = std::collections::HashSet<K, BuildHasherDefault<std::collections::hash_map::DefaultHasher>>;
15