Switch to Rust 2021 (#10170)

* Switch to Rust 2021

* Update trybuild to fix errors

substrate/client/finality-grandpa/Cargo.toml

@@ -2,7 +2,7 @@
 name = "sc-finality-grandpa"
 version = "0.10.0-dev"
 authors = ["Parity Technologies <admin@parity.io>"]
-edition = "2018"
+edition = "2021"
 license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 homepage = "https://substrate.io"
 repository = "https://github.com/paritytech/substrate/"

substrate/client/finality-grandpa/rpc/Cargo.toml

@@ -4,7 +4,7 @@ version = "0.10.0-dev"
 authors = ["Parity Technologies <admin@parity.io>"]
 description = "RPC extensions for the GRANDPA finality gadget"
 repository = "https://github.com/paritytech/substrate/"
-edition = "2018"
+edition = "2021"
 license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 readme = "README.md"
 

substrate/client/finality-grandpa/rpc/src/report.rs

@@ -87,8 +87,6 @@ impl RoundState {
 		round_state: &report::RoundState<AuthorityId>,
 		voters: &HashSet<AuthorityId>,
 	) -> Result<Self, Error> {
-		use std::convert::TryInto;
-
 		let prevotes = &round_state.prevote_ids;
 		let missing_prevotes = voters.difference(&prevotes).cloned().collect();
 
@@ -130,8 +128,6 @@ impl ReportedRoundStates {
 		AuthoritySet: ReportAuthoritySet,
 		VoterState: ReportVoterState,
 	{
-		use std::convert::TryFrom;
-
 		let voter_state = voter_state.get().ok_or(Error::EndpointNotReady)?;
 
 		let (set_id, current_voters) = authority_set.get();