put TryInto and TryFrom in sp_std::prelude (#10183)

* Switch to Rust 2021

* Update trybuild to fix errors

* half baked

* fix

* remove unused import

* remove more warnings

Co-authored-by: Bastian Köcher <info@kchr.de>

substrate/frame/election-provider-multi-phase/src/benchmarking.rs

@@ -26,10 +26,6 @@ use rand::{prelude::SliceRandom, rngs::SmallRng, SeedableRng};
 use sp_arithmetic::{per_things::Percent, traits::One};
 use sp_npos_elections::IndexAssignment;
 use sp_runtime::InnerOf;
-use sp_std::{
-	boxed::Box,
-	convert::{TryFrom, TryInto},
-};
 
 const SEED: u32 = 999;
 

substrate/frame/election-provider-multi-phase/src/helpers.rs

@@ -18,7 +18,7 @@
 //! Some helper functions/macros for this crate.
 
 use super::{Config, SolutionTargetIndexOf, SolutionVoterIndexOf, VoteWeight};
-use sp_std::{collections::btree_map::BTreeMap, convert::TryInto, prelude::*};
+use sp_std::{collections::btree_map::BTreeMap, prelude::*};
 
 #[macro_export]
 macro_rules! log {

substrate/frame/election-provider-multi-phase/src/lib.rs

@@ -255,7 +255,7 @@ use sp_runtime::{
 	},
 	DispatchError, PerThing, Perbill, RuntimeDebug, SaturatedConversion,
 };
-use sp_std::{convert::TryInto, prelude::*};
+use sp_std::prelude::*;
 
 #[cfg(feature = "runtime-benchmarks")]
 mod benchmarking;

substrate/frame/election-provider-multi-phase/src/mock.rs

@@ -40,7 +40,7 @@ use sp_runtime::{
 	traits::{BlakeTwo256, IdentityLookup},
 	PerU16,
 };
-use std::{convert::TryFrom, sync::Arc};
+use std::sync::Arc;
 
 pub type Block = sp_runtime::generic::Block<Header, UncheckedExtrinsic>;
 pub type UncheckedExtrinsic = sp_runtime::generic::UncheckedExtrinsic<AccountId, Call, (), ()>;

substrate/frame/election-provider-multi-phase/src/unsigned.rs

@@ -35,7 +35,7 @@ use sp_runtime::{
 	offchain::storage::{MutateStorageError, StorageValueRef},
 	DispatchError, SaturatedConversion,
 };
-use sp_std::{boxed::Box, cmp::Ordering, convert::TryFrom, vec::Vec};
+use sp_std::{cmp::Ordering, prelude::*};
 
 /// Storage key used to store the last block number at which offchain worker ran.
 pub(crate) const OFFCHAIN_LAST_BLOCK: &[u8] = b"parity/multi-phase-unsigned-election";