Allow default_hash_types in some crates

src/librustc/lint/internal.rs

@@ -23,7 +23,7 @@ pub struct DefaultHashTypes {
 
 impl DefaultHashTypes {
     // we are allowed to use `HashMap` and `HashSet` as identifiers for implementing the lint itself
-    #[allow(internal)]
+    #[allow(default_hash_types)]
     pub fn new() -> Self {
         let mut map = FxHashMap::default();
         map.insert(sym::HashMap, sym::FxHashMap);

src/librustc_data_structures/lib.rs

@@ -27,6 +27,7 @@
 #![cfg_attr(test, feature(test))]
 
 #![deny(rust_2018_idioms)]
+#![allow(default_hash_types)]
 
 #[macro_use]
 extern crate log;

src/librustc_macros/src/lib.rs

@@ -1,5 +1,6 @@
 #![feature(proc_macro_hygiene)]
 #![deny(rust_2018_idioms)]
+#![allow(default_hash_types)]
 
 extern crate proc_macro;