Composite accounts (#4820)

* Basic account composition.

* Add try_mutate_exists

* De-duplicate

* Refactor away the UpdateBalanceOutcome

* Expunge final UpdateBalanceOutcome refs

* Refactor transfer

* Refactor reservable currency stuff.

* Test with the alternative setup.

* Fixes

* Test with both setups.

* Fixes

* Fix

* Fix macros

* Make indices opt-in

* Remove CreationFee, and make indices opt-in.

* Fix construct_runtime

* Fix last few bits

* Fix tests

* Update trait impls

* Don't hardcode the system event

* Make tests build and fix some stuff.

* Pointlessly bump runtime version

* Fix benchmark

* Another fix

* Whitespace

* Make indices module economically safe

* Migrations for indices.

* Fix

* Whilespace

* Trim defunct migrations

* Remove unused storage item

* More contains_key fixes

* Docs.

* Bump runtime

* Remove unneeded code

* Fix test

* Fix test

* Update frame/balances/src/lib.rs

Co-Authored-By: Shawn Tabrizi <shawntabrizi@gmail.com>

* Fix ED logic

* Repatriate reserved logic

* Typo

* Fix typo

* Update frame/system/src/lib.rs

Co-Authored-By: Shawn Tabrizi <shawntabrizi@gmail.com>

* Update frame/system/src/lib.rs

Co-Authored-By: Shawn Tabrizi <shawntabrizi@gmail.com>

* Last few fixes

* Another fix

* Build fix

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
Co-authored-by: Jaco Greeff <jacogr@gmail.com>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/frame/staking/src/lib.rs

@@ -250,7 +250,6 @@
 mod mock;
 #[cfg(test)]
 mod tests;
-mod migration;
 mod slashing;
 
 pub mod inflation;
@@ -761,9 +760,6 @@ decl_storage! {
 
 		/// The earliest era for which we have a pending, unapplied slash.
 		EarliestUnappliedSlash: Option<EraIndex>;
-
-		/// The version of storage for upgrade.
-		StorageVersion: u32;
 	}
 	add_extra_genesis {
 		config(stakers):
@@ -795,8 +791,6 @@ decl_storage! {
 					}, _ => Ok(())
 				};
 			}
-
-			StorageVersion::put(migration::CURRENT_VERSION);
 		});
 	}
 }
@@ -1298,9 +1292,10 @@ impl<T: Trait> Module<T> {
 	}
 
 	/// Ensures storage is upgraded to most recent necessary state.
-	fn ensure_storage_upgraded() {
-		migration::perform_migrations::<T>();
-	}
+	///
+	/// Right now it's a no-op as all networks that are supported by Substrate Frame Core are
+	/// running with the latest staking storage scheme.
+	fn ensure_storage_upgraded() {}
 
 	/// Actually make a payment to a staker. This uses the currency's reward function
 	/// to pay the right payee for the given staker account.

substrate/frame/staking/src/migration.rs

@@ -1,140 +0,0 @@
-// Copyright 2019-2020 Parity Technologies (UK) Ltd.
-// This file is part of Substrate.
-
-// Substrate is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-
-// Substrate is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
-
-//! Storage migrations for srml-staking.
-
-/// Indicator of a version of a storage layout.
-pub type VersionNumber = u32;
-
-// the current expected version of the storage
-pub const CURRENT_VERSION: VersionNumber = 2;
-
-/// The inner logic of migrations.
-#[cfg(any(test, feature = "migrate"))]
-pub mod inner {
-	use crate::{Store, Module, Trait};
-	use frame_support::{StorageLinkedMap, StoragePrefixedMap, StorageValue};
-	use codec::{Encode, Decode};
-	use sp_std::vec::Vec;
-	use super::{CURRENT_VERSION, VersionNumber};
-
-	// the minimum supported version of the migration logic.
-	const MIN_SUPPORTED_VERSION: VersionNumber = 0;
-
-	// migrate storage from v0 to v1.
-	//
-	// this upgrades the `Nominators` linked_map value type from `Vec<T::AccountId>` to
-	// `Option<Nominations<T::AccountId>>`
-	pub fn to_v1<T: Trait>(version: &mut VersionNumber) {
-		if *version != 0 { return }
-		*version += 1;
-
-		let now = <Module<T>>::current_era();
-		let res = <Module<T> as Store>::Nominators::translate::<T::AccountId, Vec<T::AccountId>, _, _>(
-			|key| key,
-			|targets| crate::Nominations {
-				targets,
-				submitted_in: now,
-				suppressed: false,
-			},
-		);
-
-		if let Err(e) = res {
-			frame_support::print("Encountered error in migration of Staking::Nominators map.");
-			if e.is_none() {
-				frame_support::print("Staking::Nominators map reinitialized");
-			}
-		}
-
-		frame_support::print("Finished migrating Staking storage to v1.");
-	}
-
-	// migrate storage from v1 to v2: adds another field to the `SlashingSpans`
-	// struct.
-	pub fn to_v2<T: Trait>(version: &mut VersionNumber) {
-		use crate::{EraIndex, slashing::SpanIndex};
-		#[derive(Decode)]
-		struct V1SlashingSpans {
-			span_index: SpanIndex,
-			last_start: EraIndex,
-			prior: Vec<EraIndex>,
-		}
-
-		#[derive(Encode)]
-		struct V2SlashingSpans {
-			span_index: SpanIndex,
-			last_start: EraIndex,
-			last_nonzero_slash: EraIndex,
-			prior: Vec<EraIndex>,
-		}
-
-		if *version != 1 { return }
-		*version += 1;
-
-		let prefix = <Module<T> as Store>::SlashingSpans::final_prefix();
-		let mut current_key = prefix.to_vec();
-		loop {
-			let maybe_next_key = sp_io::storage::next_key(&current_key[..])
-				.filter(|v| v.starts_with(&prefix[..]));
-
-			match maybe_next_key {
-				Some(next_key) => {
-					let maybe_spans = sp_io::storage::get(&next_key[..])
-						.and_then(|v| V1SlashingSpans::decode(&mut &v[..]).ok());
-					if let Some(spans) = maybe_spans {
-						let new_val = V2SlashingSpans {
-							span_index: spans.span_index,
-							last_start: spans.last_start,
-							last_nonzero_slash: spans.last_start,
-							prior: spans.prior,
-						}.encode();
-
-						sp_io::storage::set(&next_key[..], &new_val[..]);
-					}
-					current_key = next_key;
-				}
-				None => break,
-			}
-		}
-	}
-
-	pub(super) fn perform_migrations<T: Trait>() {
-		<Module<T> as Store>::StorageVersion::mutate(|version| {
-			if *version < MIN_SUPPORTED_VERSION {
-				frame_support::print("Cannot migrate staking storage because version is less than\
-					minimum.");
-				frame_support::print(*version);
-				return
-			}
-
-			if *version == CURRENT_VERSION { return }
-
-			to_v1::<T>(version);
-			to_v2::<T>(version);
-		});
-	}
-}
-
-#[cfg(not(any(test, feature = "migrate")))]
-mod inner {
-	pub(super) fn perform_migrations<T>() { }
-}
-
-/// Perform all necessary storage migrations to get storage into the expected stsate for current
-/// logic. No-op if fully upgraded.
-pub(crate) fn perform_migrations<T: crate::Trait>() {
-	inner::perform_migrations::<T>();
-}

substrate/frame/staking/src/mock.rs

@@ -138,19 +138,16 @@ impl frame_system::Trait for Test {
 	type MaximumBlockLength = MaximumBlockLength;
 	type Version = ();
 	type ModuleToIndex = ();
-}
-parameter_types! {
-	pub const CreationFee: Balance = 0;
+	type AccountData = pallet_balances::AccountData<u64>;
+	type OnNewAccount = ();
+	type OnReapAccount = (Balances, Staking, Session);
 }
 impl pallet_balances::Trait for Test {
 	type Balance = Balance;
-	type OnReapAccount = (System, Staking);
-	type OnNewAccount = ();
 	type Event = ();
-	type TransferPayment = ();
 	type DustRemoval = ();
 	type ExistentialDeposit = ExistentialDeposit;
-	type CreationFee = CreationFee;
+	type AccountStore = System;
 }
 parameter_types! {
 	pub const Period: BlockNumber = 1;

substrate/frame/staking/src/tests.rs

@@ -18,7 +18,6 @@
 
 use super::*;
 use mock::*;
-use codec::Encode;
 use sp_runtime::{assert_eq_error_rate, traits::{OnInitialize, BadOrigin}};
 use sp_staking::offence::OffenceDetails;
 use frame_support::{
@@ -2671,13 +2670,6 @@ fn remove_multi_deferred() {
 	})
 }
 
-#[test]
-fn version_initialized() {
-	ExtBuilder::default().build().execute_with(|| {
-		assert_eq!(<Staking as Store>::StorageVersion::get(), crate::migration::CURRENT_VERSION);
-	});
-}
-
 #[test]
 fn slash_kicks_validators_not_nominators() {
 	ExtBuilder::default().build().execute_with(|| {
@@ -2717,56 +2709,6 @@ fn slash_kicks_validators_not_nominators() {
 	});
 }
 
-#[test]
-fn migration_v2() {
-	ExtBuilder::default().build().execute_with(|| {
-		use crate::{EraIndex, slashing::SpanIndex};
-
-		#[derive(Encode)]
-		struct V1SlashingSpans {
-			span_index: SpanIndex,
-			last_start: EraIndex,
-			prior: Vec<EraIndex>,
-		}
-
-		// inject old-style values directly into storage.
-		let set = |stash, spans: V1SlashingSpans| {
-			let key = <Staking as Store>::SlashingSpans::hashed_key_for(stash);
-			sp_io::storage::set(&key, &spans.encode());
-		};
-
-		let spans_11 = V1SlashingSpans {
-			span_index: 10,
-			last_start: 1,
-			prior: vec![0],
-		};
-
-		let spans_21 = V1SlashingSpans {
-			span_index: 1,
-			last_start: 5,
-			prior: vec![],
-		};
-
-		set(11, spans_11);
-		set(21, spans_21);
-
-		<Staking as Store>::StorageVersion::put(1);
-
-		// perform migration.
-		crate::migration::inner::to_v2::<Test>(&mut 1);
-
-		assert_eq!(
-			<Staking as Store>::SlashingSpans::get(&11).unwrap().last_nonzero_slash(),
-			1,
-		);
-
-		assert_eq!(
-			<Staking as Store>::SlashingSpans::get(&21).unwrap().last_nonzero_slash(),
-			5,
-		);
-	});
-}
-
 #[test]
 fn zero_slash_keeps_nominators() {
 	ExtBuilder::default().build().execute_with(|| {