sp-std -> core (#3199)

First in a series of PRs that reduces our use of sp-std with a view to
deprecating it.

This is just looking at /substrate and moving some of the references
from `sp-std` to `core`.
These particular changes should be uncontroversial.

Where macros are used `::core` should be used to remove any ambiguity.

part of #2101

Author: gilescope

substrate/frame/alliance/src/benchmarking.rs

@@ -19,13 +19,12 @@
 
 #![cfg(feature = "runtime-benchmarks")]
 
-use sp_runtime::traits::{Bounded, Hash, StaticLookup};
-use sp_std::{
+use core::{
 	cmp,
 	convert::{TryFrom, TryInto},
 	mem::size_of,
-	prelude::*,
 };
+use sp_runtime::traits::{Bounded, Hash, StaticLookup};
 
 use frame_benchmarking::{account, impl_benchmark_test_suite, v2::*, BenchmarkError};
 use frame_support::traits::{EnsureOrigin, Get, UnfilteredDispatchable};

substrate/frame/alliance/src/mock.rs

@@ -17,13 +17,13 @@
 
 //! Test utilities
 
+use core::convert::{TryFrom, TryInto};
 pub use sp_core::H256;
 use sp_runtime::traits::Hash;
 pub use sp_runtime::{
 	traits::{BlakeTwo256, IdentifyAccount, Lazy, Verify},
 	BuildStorage,
 };
-use sp_std::convert::{TryFrom, TryInto};
 
 pub use frame_support::{
 	assert_noop, assert_ok, derive_impl, ord_parameter_types, parameter_types,

substrate/frame/asset-conversion/src/mock.rs

@@ -19,6 +19,7 @@
 
 use super::*;
 use crate as pallet_asset_conversion;
+use core::default::Default;
 use frame_support::{
 	construct_runtime, derive_impl,
 	instances::{Instance1, Instance2},
@@ -39,7 +40,6 @@ use sp_runtime::{
 	traits::{AccountIdConversion, BlakeTwo256, IdentityLookup},
 	BuildStorage,
 };
-use sp_std::default::Default;
 
 type Block = frame_system::mocking::MockBlock<Test>;
 

substrate/frame/asset-conversion/src/types.rs

@@ -17,8 +17,8 @@
 
 use super::*;
 use codec::{Decode, Encode, MaxEncodedLen};
+use core::marker::PhantomData;
 use scale_info::TypeInfo;
-use sp_std::marker::PhantomData;
 
 /// Represents a swap path with associated asset amounts indicating how much of the asset needs to
 /// be deposited to get the following asset's amount withdrawn (this is inclusive of fees).

substrate/frame/assets/src/extra_mutator.rs

@@ -38,7 +38,7 @@ impl<T: Config<I>, I: 'static> Drop for ExtraMutator<T, I> {
 	}
 }
 
-impl<T: Config<I>, I: 'static> sp_std::ops::Deref for ExtraMutator<T, I> {
+impl<T: Config<I>, I: 'static> core::ops::Deref for ExtraMutator<T, I> {
 	type Target = T::Extra;
 	fn deref(&self) -> &T::Extra {
 		match self.pending {
@@ -48,7 +48,7 @@ impl<T: Config<I>, I: 'static> sp_std::ops::Deref for ExtraMutator<T, I> {
 	}
 }
 
-impl<T: Config<I>, I: 'static> sp_std::ops::DerefMut for ExtraMutator<T, I> {
+impl<T: Config<I>, I: 'static> core::ops::DerefMut for ExtraMutator<T, I> {
 	fn deref_mut(&mut self) -> &mut T::Extra {
 		if self.pending.is_none() {
 			self.pending = Some(self.original.clone());
@@ -60,7 +60,7 @@ impl<T: Config<I>, I: 'static> sp_std::ops::DerefMut for ExtraMutator<T, I> {
 impl<T: Config<I>, I: 'static> ExtraMutator<T, I> {
 	pub(super) fn maybe_new(
 		id: T::AssetId,
-		who: impl sp_std::borrow::Borrow<T::AccountId>,
+		who: impl core::borrow::Borrow<T::AccountId>,
 	) -> Option<ExtraMutator<T, I>> {
 		if let Some(a) = Account::<T, I>::get(&id, who.borrow()) {
 			Some(ExtraMutator::<T, I> {

substrate/frame/assets/src/migration.rs

@@ -64,7 +64,7 @@ pub mod v1 {
 		}
 	}
 
-	pub struct MigrateToV1<T>(sp_std::marker::PhantomData<T>);
+	pub struct MigrateToV1<T>(core::marker::PhantomData<T>);
 	impl<T: Config> OnRuntimeUpgrade for MigrateToV1<T> {
 		fn on_runtime_upgrade() -> Weight {
 			let current_version = Pallet::<T>::current_storage_version();

substrate/frame/assets/src/types.rs

@@ -123,7 +123,7 @@ where
 			return None
 		}
 		if let ExistenceReason::DepositHeld(deposit) =
-			sp_std::mem::replace(self, ExistenceReason::DepositRefunded)
+			core::mem::replace(self, ExistenceReason::DepositRefunded)
 		{
 			Some(deposit)
 		} else {
@@ -136,7 +136,7 @@ where
 			return None
 		}
 		if let ExistenceReason::DepositFrom(depositor, deposit) =
-			sp_std::mem::replace(self, ExistenceReason::DepositRefunded)
+			core::mem::replace(self, ExistenceReason::DepositRefunded)
 		{
 			Some((depositor, deposit))
 		} else {

substrate/frame/atomic-swap/src/lib.rs

@@ -43,6 +43,10 @@
 mod tests;
 
 use codec::{Decode, Encode};
+use core::{
+	marker::PhantomData,
+	ops::{Deref, DerefMut},
+};
 use frame_support::{
 	dispatch::DispatchResult,
 	pallet_prelude::MaxEncodedLen,
@@ -54,11 +58,6 @@ use frame_system::pallet_prelude::BlockNumberFor;
 use scale_info::TypeInfo;
 use sp_io::hashing::blake2_256;
 use sp_runtime::RuntimeDebug;
-use sp_std::{
-	marker::PhantomData,
-	ops::{Deref, DerefMut},
-	prelude::*,
-};
 
 /// Pending atomic swap operation.
 #[derive(Clone, Eq, PartialEq, RuntimeDebugNoBound, Encode, Decode, TypeInfo, MaxEncodedLen)]

substrate/frame/aura/src/migrations.rs

@@ -19,7 +19,7 @@
 
 use frame_support::{pallet_prelude::*, traits::Get, weights::Weight};
 
-struct __LastTimestamp<T>(sp_std::marker::PhantomData<T>);
+struct __LastTimestamp<T>(core::marker::PhantomData<T>);
 impl<T: RemoveLastTimestamp> frame_support::traits::StorageInstance for __LastTimestamp<T> {
 	fn pallet_prefix() -> &'static str {
 		T::PalletPrefix::get()

substrate/frame/babe/src/randomness.rs

@@ -51,7 +51,7 @@ use sp_runtime::traits::{Hash, One, Saturating};
 ///
 /// Adversaries should not possess many block production slots towards the beginning or
 /// end of every epoch, but they possess some influence over when they possess more slots.
-pub struct RandomnessFromTwoEpochsAgo<T>(sp_std::marker::PhantomData<T>);
+pub struct RandomnessFromTwoEpochsAgo<T>(core::marker::PhantomData<T>);
 
 /// Randomness usable by on-chain code that **does not depend** upon finality and takes
 /// action based upon on-chain commitments made during the previous epoch.
@@ -79,7 +79,7 @@ pub struct RandomnessFromTwoEpochsAgo<T>(sp_std::marker::PhantomData<T>);
 /// As an example usage, we determine parachain auctions ending times in Polkadot using
 /// `RandomnessFromOneEpochAgo` because it reduces bias from `ParentBlockRandomness` and
 /// does not require the extra finality delay of `RandomnessFromTwoEpochsAgo`.
-pub struct RandomnessFromOneEpochAgo<T>(sp_std::marker::PhantomData<T>);
+pub struct RandomnessFromOneEpochAgo<T>(core::marker::PhantomData<T>);
 
 /// Randomness produced semi-freshly with each block, but inherits limitations of
 /// `RandomnessFromTwoEpochsAgo` from which it derives.
@@ -119,7 +119,7 @@ pub struct RandomnessFromOneEpochAgo<T>(sp_std::marker::PhantomData<T>);
 /// instead you are using this randomness externally, i.e. after block execution, then
 /// this randomness will be provided by the "current" block (this stems from the fact that
 /// we process VRF outputs on block execution finalization, i.e. `on_finalize`).
-pub struct ParentBlockRandomness<T>(sp_std::marker::PhantomData<T>);
+pub struct ParentBlockRandomness<T>(core::marker::PhantomData<T>);
 
 /// Randomness produced semi-freshly with each block, but inherits limitations of
 /// `RandomnessFromTwoEpochsAgo` from which it derives.
@@ -128,7 +128,7 @@ pub struct ParentBlockRandomness<T>(sp_std::marker::PhantomData<T>);
 #[deprecated(note = "Should not be relied upon for correctness, \
 					 will not provide fresh randomness for the current block. \
 					 Please use `ParentBlockRandomness` instead.")]
-pub struct CurrentBlockRandomness<T>(sp_std::marker::PhantomData<T>);
+pub struct CurrentBlockRandomness<T>(core::marker::PhantomData<T>);
 
 impl<T: Config> RandomnessT<T::Hash, BlockNumberFor<T>> for RandomnessFromTwoEpochsAgo<T> {
 	fn random(subject: &[u8]) -> (T::Hash, BlockNumberFor<T>) {