Enable extra warnings required by rust-lang/rust

crates/proc-macro-api/src/lib.rs

@@ -5,6 +5,8 @@
 //! is used to provide basic infrastructure for communication between two
 //! processes: Client (RA itself), Server (the external program)
 
+#![warn(rust_2018_idioms, unused_lifetimes, semicolon_in_expressions_from_macros)]
+
 pub mod msg;
 mod process;
 mod version;