diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index e1f6e1caeae..6adfaa53946 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -141,15 +141,8 @@ pub mod util {
     pub mod bug;
 }
 
-// A private module so that macro-expanded idents like
-// `::rustc::lint::Lint` will also work in `rustc` itself.
-//
-// `libstd` uses the same trick.
-#[doc(hidden)]
-mod rustc {
-    pub use crate::lint;
-    pub use crate::ich;
-}
+// Allows macros to refer to this crate as `::rustc`
+extern crate self as rustc;
 
 // FIXME(#27438): right now the unit tests of librustc don't refer to any actual
 //                functions generated in librustc_data_structures (all
diff --git a/src/librustc_macros/Cargo.toml b/src/librustc_macros/Cargo.toml
index c5e01e9e0a7..2fe51a22fb4 100644
--- a/src/librustc_macros/Cargo.toml
+++ b/src/librustc_macros/Cargo.toml
@@ -2,6 +2,7 @@
 name = "rustc_macros"
 version = "0.1.0"
 authors = ["The Rust Project Developers"]
+edition = "2018"
 
 [lib]
 proc-macro = true
@@ -10,4 +11,4 @@ proc-macro = true
 synstructure = "0.10.1"
 syn = { version = "0.15.22", features = ["full"] }
 proc-macro2 = "0.4.24"
-quote = "0.6.10"
\ No newline at end of file
+quote = "0.6.10"
diff --git a/src/librustc_macros/src/hash_stable.rs b/src/librustc_macros/src/hash_stable.rs
index 13899d68cd2..6d7590c7d1c 100644
--- a/src/librustc_macros/src/hash_stable.rs
+++ b/src/librustc_macros/src/hash_stable.rs
@@ -1,6 +1,7 @@
 use synstructure;
-use syn::{self, Meta, NestedMeta};
+use syn::{self, Meta, NestedMeta, parse_quote};
 use proc_macro2::{self, Ident};
+use quote::quote;
 
 struct Attributes {
     ignore: bool,
@@ -46,7 +47,7 @@ fn parse_attributes(field: &syn::Field) -> Attributes {
     attrs
 }
 
-pub fn hash_stable_derive(mut s: synstructure::Structure) -> proc_macro2::TokenStream {
+pub fn hash_stable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
     let generic: syn::GenericParam = parse_quote!('__ctx);
     s.add_bounds(synstructure::AddBounds::Generics);
     s.add_impl_generic(generic);
diff --git a/src/librustc_macros/src/lib.rs b/src/librustc_macros/src/lib.rs
index 460b415c537..cad31264b05 100644
--- a/src/librustc_macros/src/lib.rs
+++ b/src/librustc_macros/src/lib.rs
@@ -1,13 +1,7 @@
 #![feature(proc_macro_hygiene)]
+#![deny(rust_2018_idioms)]
 
-#[macro_use]
-extern crate syn;
-#[macro_use]
-extern crate synstructure;
-#[macro_use]
-extern crate quote;
-extern crate proc_macro;
-extern crate proc_macro2;
+use synstructure::decl_derive;
 
 mod hash_stable;