Switch to Rust 2021 (#10170)

* Switch to Rust 2021

* Update trybuild to fix errors

substrate/client/network/Cargo.toml

@@ -4,7 +4,7 @@ name = "sc-network"
 version = "0.10.0-dev"
 license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 authors = ["Parity Technologies <admin@parity.io>"]
-edition = "2018"
+edition = "2021"
 homepage = "https://substrate.io"
 repository = "https://github.com/paritytech/substrate/"
 documentation = "https://docs.rs/sc-network"

substrate/client/network/src/protocol/sync.rs

@@ -2172,7 +2172,6 @@ impl<B: BlockT> ChainSync<B> {
 
 	/// Return some key metrics.
 	pub(crate) fn metrics(&self) -> Metrics {
-		use std::convert::TryInto;
 		Metrics {
 			queued_blocks: self.queue_blocks.len().try_into().unwrap_or(std::u32::MAX),
 			fork_targets: self.fork_targets.len().try_into().unwrap_or(std::u32::MAX),

substrate/client/network/src/protocol/sync/extra_requests.rs

@@ -255,7 +255,6 @@ impl<B: BlockT> ExtraRequests<B> {
 
 	/// Get some key metrics.
 	pub(crate) fn metrics(&self) -> Metrics {
-		use std::convert::TryInto;
 		Metrics {
 			pending_requests: self.pending_requests.len().try_into().unwrap_or(std::u32::MAX),
 			active_requests: self.active_requests.len().try_into().unwrap_or(std::u32::MAX),

substrate/client/network/test/Cargo.toml

@@ -4,7 +4,7 @@ name = "sc-network-test"
 version = "0.8.0"
 license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 authors = ["Parity Technologies <admin@parity.io>"]
-edition = "2018"
+edition = "2021"
 publish = false
 homepage = "https://substrate.io"
 repository = "https://github.com/paritytech/substrate/"