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-current-thread/tests/current_thread.rs

@@ -22,7 +22,7 @@ use futures::sync::oneshot;
 
 mod from_block_on_all {
     use super::*;
-    fn test<F: Fn(Box<Future<Item = (), Error = ()>>) + 'static>(spawn: F) {
+    fn test<F: Fn(Box<dyn Future<Item = (), Error = ()>>) + 'static>(spawn: F) {
         let cnt = Rc::new(Cell::new(0));
         let c = cnt.clone();
 
@@ -102,7 +102,7 @@ fn spawn_many() {
 mod does_not_set_global_executor_by_default {
     use super::*;
 
-    fn test<F: Fn(Box<Future<Item = (), Error = ()> + Send>) -> Result<(), E> + 'static, E>(
+    fn test<F: Fn(Box<dyn Future<Item = (), Error = ()> + Send>) -> Result<(), E> + 'static, E>(
         spawn: F,
     ) {
         block_on_all(lazy(|| {
@@ -127,7 +127,7 @@ mod does_not_set_global_executor_by_default {
 mod from_block_on_future {
     use super::*;
 
-    fn test<F: Fn(Box<Future<Item = (), Error = ()>>)>(spawn: F) {
+    fn test<F: Fn(Box<dyn Future<Item = (), Error = ()>>)>(spawn: F) {
         let cnt = Rc::new(Cell::new(0));
 
         let mut tokio_current_thread = CurrentThread::new();
@@ -181,8 +181,8 @@ mod outstanding_tasks_are_dropped_when_executor_is_dropped {
 
     fn test<F, G>(spawn: F, dotspawn: G)
     where
-        F: Fn(Box<Future<Item = (), Error = ()>>) + 'static,
-        G: Fn(&mut CurrentThread, Box<Future<Item = (), Error = ()>>),
+        F: Fn(Box<dyn Future<Item = (), Error = ()>>) + 'static,
+        G: Fn(&mut CurrentThread, Box<dyn Future<Item = (), Error = ()>>),
     {
         let mut rc = Rc::new(());
 
@@ -383,8 +383,8 @@ mod and_turn {
 
     fn test<F, G>(spawn: F, dotspawn: G)
     where
-        F: Fn(Box<Future<Item = (), Error = ()>>) + 'static,
-        G: Fn(&mut CurrentThread, Box<Future<Item = (), Error = ()>>),
+        F: Fn(Box<dyn Future<Item = (), Error = ()>>) + 'static,
+        G: Fn(&mut CurrentThread, Box<dyn Future<Item = (), Error = ()>>),
     {
         let cnt = Rc::new(Cell::new(0));
         let c = cnt.clone();
@@ -459,7 +459,7 @@ mod in_drop {
     }
 
     struct MyFuture {
-        _data: Box<Any>,
+        _data: Box<dyn Any>,
     }
 
     impl Future for MyFuture {
@@ -473,8 +473,8 @@ mod in_drop {
 
     fn test<F, G>(spawn: F, dotspawn: G)
     where
-        F: Fn(Box<Future<Item = (), Error = ()>>) + 'static,
-        G: Fn(&mut CurrentThread, Box<Future<Item = (), Error = ()>>),
+        F: Fn(Box<dyn Future<Item = (), Error = ()>>) + 'static,
+        G: Fn(&mut CurrentThread, Box<dyn Future<Item = (), Error = ()>>),
     {
         let mut tokio_current_thread = CurrentThread::new();