v0.1.x lint fix, MSRV 1.28.0 updates (#1451)

* use dyn Trait syntax where appropriate

recent rust nightly started warning that not using `dyn` was
deprecated. This requires MSRV 1.27.0+.

* rustfmt fallout from dyn additions

* stop explicit allow of rust_2018_idioms

* more dyn Trait syntax

* drop tokio-macros from 0.1.x workspace

Since tokio-macros specifies an edition=2018, we would otherwise
require MSRV 1.31.0 to build/test it. And tokio-macros isn't used with
tokio 0.1.x.

* reactor: narrow tokio-io-pool dev dep to 0.1.4

Since 0.1.5-6 is now a edition=2018 crate, which has effective MSRV
1.31.0.

* narrow tempfile dev-dep to avoid MSRV bump

tempfile 3.1.0 pulls in rand 0.7.0 and is MSRV 1.32.0

* narrow flate2 dev-dep to avoid MSRV bump

flate2 1.0.10-11 have MSRV 1.34.0.

github refs: alexcrichton/flate2-rs#207

* fs: drop deprecated tempdir crate use in tests

In particular because it pulls in old rand duplicates. Replace use
with tempfile::tempdir() which has been available since tempfile
3.0.0.

backport-of: #1312

* increase CI MSRV to 1.28.0

tokio-threadpool/src/builder.rs

@@ -67,7 +67,7 @@ pub struct Builder {
     max_blocking: usize,
 
     /// Generates the `Park` instances
-    new_park: Box<Fn(&WorkerId) -> BoxPark>,
+    new_park: Box<dyn Fn(&WorkerId) -> BoxPark>,
 }
 
 impl Builder {
@@ -223,7 +223,7 @@ impl Builder {
     /// ```
     pub fn panic_handler<F>(&mut self, f: F) -> &mut Self
     where
-        F: Fn(Box<Any + Send>) + Send + Sync + 'static,
+        F: Fn(Box<dyn Any + Send>) + Send + Sync + 'static,
     {
         self.config.panic_handler = Some(Arc::new(f));
         self

tokio-threadpool/src/callback.rs

@@ -7,7 +7,7 @@ use tokio_executor::Enter;
 
 #[derive(Clone)]
 pub(crate) struct Callback {
-    f: Arc<Fn(&Worker, &mut Enter) + Send + Sync>,
+    f: Arc<dyn Fn(&Worker, &mut Enter) + Send + Sync>,
 }
 
 impl Callback {

tokio-threadpool/src/config.rs

@@ -13,9 +13,9 @@ pub(crate) struct Config {
     pub name_prefix: Option<String>,
     pub stack_size: Option<usize>,
     pub around_worker: Option<Callback>,
-    pub after_start: Option<Arc<Fn() + Send + Sync>>,
-    pub before_stop: Option<Arc<Fn() + Send + Sync>>,
-    pub panic_handler: Option<Arc<Fn(Box<Any + Send>) + Send + Sync>>,
+    pub after_start: Option<Arc<dyn Fn() + Send + Sync>>,
+    pub before_stop: Option<Arc<dyn Fn() + Send + Sync>>,
+    pub panic_handler: Option<Arc<dyn Fn(Box<dyn Any + Send>) + Send + Sync>>,
 }
 
 /// Max number of workers that can be part of a pool. This is the most that can

tokio-threadpool/src/lib.rs

@@ -1,7 +1,5 @@
 #![doc(html_root_url = "https://docs.rs/tokio-threadpool/0.1.15")]
 #![deny(warnings, missing_docs, missing_debug_implementations)]
-// Our MSRV doesn't allow us to fix these warnings yet
-#![allow(rust_2018_idioms)]
 
 //! A work-stealing based thread pool for executing futures.
 //!

tokio-threadpool/src/park/boxed.rs

@@ -3,8 +3,8 @@ use tokio_executor::park::{Park, Unpark};
 use std::error::Error;
 use std::time::Duration;
 
-pub(crate) type BoxPark = Box<Park<Unpark = BoxUnpark, Error = ()> + Send>;
-pub(crate) type BoxUnpark = Box<Unpark>;
+pub(crate) type BoxPark = Box<dyn Park<Unpark = BoxUnpark, Error = ()> + Send>;
+pub(crate) type BoxUnpark = Box<dyn Unpark>;
 
 pub(crate) struct BoxedPark<T>(T);
 

tokio-threadpool/src/sender.rs

@@ -131,7 +131,7 @@ impl tokio_executor::Executor for Sender {
 
     fn spawn(
         &mut self,
-        future: Box<Future<Item = (), Error = ()> + Send>,
+        future: Box<dyn Future<Item = (), Error = ()> + Send>,
     ) -> Result<(), SpawnError> {
         let mut s = &*self;
         tokio_executor::Executor::spawn(&mut s, future)
@@ -157,7 +157,7 @@ impl<'a> tokio_executor::Executor for &'a Sender {
 
     fn spawn(
         &mut self,
-        future: Box<Future<Item = (), Error = ()> + Send>,
+        future: Box<dyn Future<Item = (), Error = ()> + Send>,
     ) -> Result<(), SpawnError> {
         self.prepare_for_spawn()?;
 

tokio-threadpool/src/task/mod.rs

@@ -60,7 +60,7 @@ pub(crate) enum Run {
     Complete,
 }
 
-type BoxFuture = Box<Future<Item = (), Error = ()> + Send + 'static>;
+type BoxFuture = Box<dyn Future<Item = (), Error = ()> + Send + 'static>;
 
 // ===== impl Task =====