Convert sort_by to sort_by_cached_key

3 files changed, 5 insertions, 9 deletions

diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index 6f88b0aecb6..ab710f2e900 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -23,6 +23,7 @@
 #![cfg_attr(unix, feature(libc))]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
+#![feature(slice_sort_by_cached_key)]
 #![feature(set_stdio)]
 #![feature(rustc_stack_internals)]
 
@@ -83,7 +84,6 @@ use rustc_trans_utils::trans_crate::TransCrate;
 use serialize::json::ToJson;
 
 use std::any::Any;
-use std::cmp::Ordering::Equal;
 use std::cmp::max;
 use std::default::Default;
 use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
@@ -1177,13 +1177,8 @@ Available lint options:
 
     fn sort_lints(sess: &Session, lints: Vec<(&'static Lint, bool)>) -> Vec<&'static Lint> {
         let mut lints: Vec<_> = lints.into_iter().map(|(x, _)| x).collect();
-        lints.sort_by(|x: &&Lint, y: &&Lint| {
-            match x.default_level(sess).cmp(&y.default_level(sess)) {
-                // The sort doesn't case-fold but it's doubtful we care.
-                Equal => x.name.cmp(y.name),
-                r => r,
-            }
-        });
+        // The sort doesn't case-fold but it's doubtful we care.
+        lints.sort_by_cached_key(|x: &&Lint| (x.default_level(sess), x.name));
         lints
     }
 
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index c456dc45d21..7774095e204 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -22,6 +22,7 @@
 
 #![feature(unicode)]
 #![feature(rustc_diagnostic_macros)]
+#![feature(slice_sort_by_cached_key)]
 #![feature(non_exhaustive)]
 #![feature(const_atomic_usize_new)]
 #![feature(rustc_attrs)]
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index e6da5bcaa3a..6ed7088d052 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -689,7 +689,7 @@ impl<'a> Parser<'a> {
                 .chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
                 .chain(self.expected_tokens.iter().cloned())
                 .collect::<Vec<_>>();
-            expected.sort_by(|a, b| a.to_string().cmp(&b.to_string()));
+            expected.sort_by_cached_key(|x| x.to_string());
             expected.dedup();
             let expect = tokens_to_string(&expected[..]);
             let actual = self.this_token_to_string();