Rollup merge of #58835 - Centril:rust_2018_idioms-remote-test, r=oli-obk

tools/remote-test-{client,server}: deny(rust_2018_idioms) r? @oli-obk (+ tiny amount of cleanup)

Author: kennytm

src/tools/remote-test-client/src/main.rs

@@ -1,3 +1,5 @@
+#![deny(rust_2018_idioms)]
+
 /// This is a small client program intended to pair with `remote-test-server` in
 /// this repository. This client connects to the server over TCP and is used to
 /// push artifacts and run tests on the server instead of locally.
@@ -15,7 +17,7 @@ use std::process::{Command, Stdio};
 use std::thread;
 use std::time::Duration;
 
-const REMOTE_ADDR_ENV: &'static str = "TEST_DEVICE_ADDR";
+const REMOTE_ADDR_ENV: &str = "TEST_DEVICE_ADDR";
 
 macro_rules! t {
  ($e:expr) => (match $e {

src/tools/remote-test-server/src/main.rs

@@ -1,3 +1,5 @@
+#![deny(rust_2018_idioms)]
+
 /// This is a small server which is intended to run inside of an emulator or
 /// on a remote test device. This server pairs with the `remote-test-client`
 /// program in this repository. The `remote-test-client` connects to this
@@ -120,7 +122,7 @@ struct RemoveOnDrop<'a> {
  inner: &'a Path,
 }
 
-impl<'a> Drop for RemoveOnDrop<'a> {
+impl Drop for RemoveOnDrop<'_> {
  fn drop(&mut self) {
  t!(fs::remove_dir_all(self.inner));
  }