Remove Default bound for AccountId (#10403)

* Remove Default for AccountId

* More removals of default

* Update frame/authorship/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update frame/authorship/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update frame/authorship/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update frame/authorship/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* More work

* More work

* Remove old code

* More work

* pallet-asset-tx-payment

* tips

* sc-consensus-babe

* sc-finality-grandpa

* sc-consensus-babe-rpc

* sc-cli

* make npos crates accept non-default account (#10420)

* minimal changes to make npos pallets all work

* make this pesky reduce.rs a bit cleaner

* more work

* more work

* Tests build

* Fix imonline tests

* Formatting

* Fixes

* Fixes

* Fix bench

* Fixes

* Fixes

* Fixes

* Fixes

* Fixes

* Formatting

* Fixes

* Formatting

* Fixes

* Formatting

* Fixes

* Formatting

* Fixes

* Formatting

* Update client/keystore/src/local.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/finality-grandpa/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/keystore/src/local.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/keystore/src/local.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update frame/staking/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update frame/staking/src/lib.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update primitives/runtime/src/traits.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Formatting

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: kianenigma <kian@parity.io>

substrate/frame/aura/src/lib.rs

@@ -69,7 +69,6 @@ pub mod pallet {
 		type AuthorityId: Member
 			+ Parameter
 			+ RuntimeAppPublic
-			+ Default
 			+ MaybeSerializeDeserialize
 			+ MaxEncodedLen;
 		/// The maximum number of authorities that the pallet can hold.

substrate/frame/authorship/src/lib.rs

@@ -170,7 +170,9 @@ pub mod pallet {
 
 			<DidSetUncles<T>>::put(false);
 
-			T::EventHandler::note_author(Self::author());
+			if let Some(author) = Self::author() {
+				T::EventHandler::note_author(author);
+			}
 
 			0
 		}
@@ -300,20 +302,18 @@ impl<T: Config> Pallet<T> {
 	///
 	/// This is safe to invoke in `on_initialize` implementations, as well
 	/// as afterwards.
-	pub fn author() -> T::AccountId {
+	pub fn author() -> Option<T::AccountId> {
 		// Check the memoized storage value.
 		if let Some(author) = <Author<T>>::get() {
-			return author
+			return Some(author)
 		}
 
 		let digest = <frame_system::Pallet<T>>::digest();
 		let pre_runtime_digests = digest.logs.iter().filter_map(|d| d.as_pre_runtime());
-		if let Some(author) = T::FindAuthor::find_author(pre_runtime_digests) {
-			<Author<T>>::put(&author);
-			author
-		} else {
-			Default::default()
-		}
+		T::FindAuthor::find_author(pre_runtime_digests).map(|a| {
+			<Author<T>>::put(&a);
+			a
+		})
 	}
 
 	fn verify_and_import_uncles(new_uncles: Vec<T::Header>) -> dispatch::DispatchResult {
@@ -329,14 +329,13 @@ impl<T: Config> Pallet<T> {
 				UncleEntryItem::InclusionHeight(_) => None,
 				UncleEntryItem::Uncle(h, _) => Some(h),
 			});
-			let author = Self::verify_uncle(&uncle, prev_uncles, &mut acc)?;
+			let maybe_author = Self::verify_uncle(&uncle, prev_uncles, &mut acc)?;
 			let hash = uncle.hash();
 
-			T::EventHandler::note_uncle(
-				author.clone().unwrap_or_default(),
-				now - uncle.number().clone(),
-			);
-			uncles.push(UncleEntryItem::Uncle(hash, author));
+			if let Some(author) = maybe_author.clone() {
+				T::EventHandler::note_uncle(author, now - uncle.number().clone());
+			}
+			uncles.push(UncleEntryItem::Uncle(hash, maybe_author));
 		}
 
 		<Uncles<T>>::put(&uncles);
@@ -693,7 +692,7 @@ mod tests {
 			header.digest_mut().pop(); // pop the seal off.
 			System::initialize(&1, &Default::default(), header.digest(), Default::default());
 
-			assert_eq!(Authorship::author(), author);
+			assert_eq!(Authorship::author(), Some(author));
 		});
 	}
 

substrate/frame/babe/src/equivocation.rs

@@ -176,7 +176,7 @@ where
 	}
 
 	fn block_author() -> Option<T::AccountId> {
-		Some(<pallet_authorship::Pallet<T>>::author())
+		<pallet_authorship::Pallet<T>>::author()
 	}
 }
 

substrate/frame/babe/src/lib.rs

@@ -31,7 +31,7 @@ use frame_support::{
 	weights::{Pays, Weight},
 	BoundedVec, WeakBoundedVec,
 };
-use sp_application_crypto::Public;
+use sp_application_crypto::ByteArray;
 use sp_runtime::{
 	generic::DigestItem,
 	traits::{IsMember, One, SaturatedConversion, Saturating, Zero},

substrate/frame/beefy-mmr/src/lib.rs

@@ -72,7 +72,7 @@ where
 pub struct BeefyEcdsaToEthereum;
 impl Convert<beefy_primitives::crypto::AuthorityId, Vec<u8>> for BeefyEcdsaToEthereum {
 	fn convert(a: beefy_primitives::crypto::AuthorityId) -> Vec<u8> {
-		use sp_core::crypto::Public;
+		use sp_core::crypto::ByteArray;
 		let compressed_key = a.as_slice();
 
 		libsecp256k1::PublicKey::parse_slice(

substrate/frame/beefy/src/lib.rs

@@ -47,7 +47,7 @@ pub mod pallet {
 	#[pallet::config]
 	pub trait Config: frame_system::Config {
 		/// Authority identifier type
-		type BeefyId: Member + Parameter + RuntimeAppPublic + Default + MaybeSerializeDeserialize;
+		type BeefyId: Member + Parameter + RuntimeAppPublic + MaybeSerializeDeserialize;
 	}
 
 	#[pallet::pallet]

substrate/frame/benchmarking/src/utils.rs

@@ -23,6 +23,7 @@ use frame_support::{
 	traits::StorageInfo,
 };
 use sp_io::hashing::blake2_256;
+use sp_runtime::traits::TrailingZeroInput;
 use sp_std::{prelude::Box, vec::Vec};
 use sp_storage::TrackedStorageKey;
 
@@ -321,17 +322,14 @@ pub trait BenchmarkingSetup<T, I = ()> {
 }
 
 /// Grab an account, seeded by a name and index.
-pub fn account<AccountId: Decode + Default>(
-	name: &'static str,
-	index: u32,
-	seed: u32,
-) -> AccountId {
+pub fn account<AccountId: Decode>(name: &'static str, index: u32, seed: u32) -> AccountId {
 	let entropy = (name, index, seed).using_encoded(blake2_256);
-	AccountId::decode(&mut &entropy[..]).unwrap_or_default()
+	Decode::decode(&mut TrailingZeroInput::new(entropy.as_ref()))
+		.expect("infinite length input; no invalid inputs for type; qed")
 }
 
 /// This caller account is automatically whitelisted for DB reads/writes by the benchmarking macro.
-pub fn whitelisted_caller<AccountId: Decode + Default>() -> AccountId {
+pub fn whitelisted_caller<AccountId: Decode>() -> AccountId {
 	account::<AccountId>("whitelisted_caller", 0, 0)
 }
 

substrate/frame/bounties/src/lib.rs

@@ -123,7 +123,7 @@ pub struct Bounty<AccountId, Balance, BlockNumber> {
 	status: BountyStatus<AccountId, BlockNumber>,
 }
 
-impl<AccountId: PartialEq + Clone + Ord + Default, Balance, BlockNumber: Clone>
+impl<AccountId: PartialEq + Clone + Ord, Balance, BlockNumber: Clone>
 	Bounty<AccountId, Balance, BlockNumber>
 {
 	/// Getter for bounty status, to be used for child bounties.

substrate/frame/collective/src/benchmarking.rs

@@ -43,9 +43,9 @@ benchmarks_instance_pallet! {
 		// Set old members.
 		// We compute the difference of old and new members, so it should influence timing.
 		let mut old_members = vec![];
-		let mut last_old_member = T::AccountId::default();
+		let mut last_old_member = account::<T::AccountId>("old member", 0, SEED);
 		for i in 0 .. m {
-			last_old_member = account("old member", i, SEED);
+			last_old_member = account::<T::AccountId>("old member", i, SEED);
 			old_members.push(last_old_member.clone());
 		}
 		let old_members_count = old_members.len() as u32;
@@ -91,9 +91,9 @@ benchmarks_instance_pallet! {
 		// Construct `new_members`.
 		// It should influence timing since it will sort this vector.
 		let mut new_members = vec![];
-		let mut last_member = T::AccountId::default();
+		let mut last_member = account::<T::AccountId>("member", 0, SEED);
 		for i in 0 .. n {
-			last_member = account("member", i, SEED);
+			last_member = account::<T::AccountId>("member", i, SEED);
 			new_members.push(last_member.clone());
 		}
 
@@ -112,7 +112,7 @@ benchmarks_instance_pallet! {
 		// Construct `members`.
 		let mut members = vec![];
 		for i in 0 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
 
@@ -142,7 +142,7 @@ benchmarks_instance_pallet! {
 		// Construct `members`.
 		let mut members = vec![];
 		for i in 0 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
 
@@ -174,7 +174,7 @@ benchmarks_instance_pallet! {
 		// Construct `members`.
 		let mut members = vec![];
 		for i in 0 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
 		let caller: T::AccountId = whitelisted_caller();
@@ -216,13 +216,13 @@ benchmarks_instance_pallet! {
 
 		// Construct `members`.
 		let mut members = vec![];
-		let proposer: T::AccountId = account("proposer", 0, SEED);
+		let proposer: T::AccountId = account::<T::AccountId>("proposer", 0, SEED);
 		members.push(proposer.clone());
 		for i in 1 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
-		let voter: T::AccountId = account("voter", 0, SEED);
+		let voter: T::AccountId = account::<T::AccountId>("voter", 0, SEED);
 		members.push(voter.clone());
 		Collective::<T, I>::set_members(SystemOrigin::Root.into(), members.clone(), None, T::MaxMembers::get())?;
 
@@ -291,13 +291,13 @@ benchmarks_instance_pallet! {
 
 		// Construct `members`.
 		let mut members = vec![];
-		let proposer: T::AccountId = account("proposer", 0, SEED);
+		let proposer = account::<T::AccountId>("proposer", 0, SEED);
 		members.push(proposer.clone());
 		for i in 1 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
-		let voter: T::AccountId = account("voter", 0, SEED);
+		let voter = account::<T::AccountId>("voter", 0, SEED);
 		members.push(voter.clone());
 		Collective::<T, I>::set_members(SystemOrigin::Root.into(), members.clone(), None, T::MaxMembers::get())?;
 
@@ -373,7 +373,7 @@ benchmarks_instance_pallet! {
 		// Construct `members`.
 		let mut members = vec![];
 		for i in 0 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
 		let caller: T::AccountId = whitelisted_caller();
@@ -454,7 +454,7 @@ benchmarks_instance_pallet! {
 		// Construct `members`.
 		let mut members = vec![];
 		for i in 0 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
 		let caller: T::AccountId = whitelisted_caller();
@@ -528,7 +528,7 @@ benchmarks_instance_pallet! {
 		// Construct `members`.
 		let mut members = vec![];
 		for i in 0 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
 		let caller: T::AccountId = whitelisted_caller();
@@ -599,10 +599,10 @@ benchmarks_instance_pallet! {
 		// Construct `members`.
 		let mut members = vec![];
 		for i in 0 .. m - 1 {
-			let member = account("member", i, SEED);
+			let member = account::<T::AccountId>("member", i, SEED);
 			members.push(member);
 		}
-		let caller: T::AccountId = account("caller", 0, SEED);
+		let caller = account::<T::AccountId>("caller", 0, SEED);
 		members.push(caller.clone());
 		Collective::<T, I>::set_members(
 			SystemOrigin::Root.into(),

substrate/frame/contracts/src/migration.rs

@@ -224,13 +224,16 @@ mod v6 {
 			})
 		});
 
+		let nobody = T::AccountId::decode(&mut sp_runtime::traits::TrailingZeroInput::zeroes())
+			.expect("Infinite input; no dead input space; qed");
+
 		<CodeStorage<T>>::translate(|key, old: OldPrefabWasmModule| {
 			weight = weight.saturating_add(T::DbWeight::get().reads_writes(1, 2));
 			<OwnerInfoOf<T>>::insert(
 				key,
 				OwnerInfo {
 					refcount: old.refcount,
-					owner: Default::default(),
+					owner: nobody.clone(),
 					deposit: Default::default(),
 				},
 			);

substrate/frame/democracy/src/benchmarking.rs

@@ -239,9 +239,14 @@ benchmarks! {
 		let origin = T::ExternalOrigin::successful_origin();
 		let proposal_hash = T::Hashing::hash_of(&0);
 		// Add proposal to blacklist with block number 0
+
+		let addresses = (0..v)
+			.into_iter()
+			.map(|i| account::<T::AccountId>("blacklist", i, SEED))
+			.collect::<Vec<_>>();
 		Blacklist::<T>::insert(
 			proposal_hash,
-			(T::BlockNumber::zero(), vec![T::AccountId::default(); v as usize])
+			(T::BlockNumber::zero(), addresses),
 		);
 	}: _<T::Origin>(origin, proposal_hash)
 	verify {
@@ -292,7 +297,7 @@ benchmarks! {
 
 		let mut vetoers: Vec<T::AccountId> = Vec::new();
 		for i in 0 .. v {
-			vetoers.push(account("vetoer", i, SEED));
+			vetoers.push(account::<T::AccountId>("vetoer", i, SEED));
 		}
 		vetoers.sort();
 		Blacklist::<T>::insert(proposal_hash, (T::BlockNumber::zero(), vetoers));

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

@@ -209,7 +209,11 @@ frame_benchmarking::benchmarks! {
 		let receiver = account("receiver", 0, SEED);
 		let initial_balance = T::Currency::minimum_balance() * 10u32.into();
 		T::Currency::make_free_balance_be(&receiver, initial_balance);
-		let ready: ReadySolution<T::AccountId> = Default::default();
+		let ready = ReadySolution {
+			supports: vec![],
+			score: Default::default(),
+			compute: Default::default()
+		};
 		let deposit: BalanceOf<T> = 10u32.into();
 		let reward: BalanceOf<T> = 20u32.into();
 
@@ -314,7 +318,12 @@ frame_benchmarking::benchmarks! {
 				score: [(10_000_000 + i).into(), 0, 0],
 				..Default::default()
 			};
-			let signed_submission = SignedSubmission { raw_solution, ..Default::default() };
+			let signed_submission = SignedSubmission {
+				raw_solution,
+				who: account("submitters", i, SEED),
+				deposit: Default::default(),
+				reward: Default::default(),
+			};
 			signed_submissions.insert(signed_submission);
 		}
 		signed_submissions.put();

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

@@ -1189,7 +1189,7 @@ pub mod pallet {
 	/// affect; we shouldn't need a cryptographically secure hasher.
 	#[pallet::storage]
 	pub(crate) type SignedSubmissionsMap<T: Config> =
-		StorageMap<_, Twox64Concat, u32, SignedSubmissionOf<T>, ValueQuery>;
+		StorageMap<_, Twox64Concat, u32, SignedSubmissionOf<T>, OptionQuery>;
 
 	// `SignedSubmissions` items end here.
 

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

@@ -42,7 +42,7 @@ use sp_std::{
 /// A raw, unchecked signed submission.
 ///
 /// This is just a wrapper around [`RawSolution`] and some additional info.
-#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug, Default, scale_info::TypeInfo)]
+#[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug, scale_info::TypeInfo)]
 pub struct SignedSubmission<AccountId, Balance: HasCompact, Solution> {
 	/// Who submitted this solution.
 	pub who: AccountId,
@@ -167,17 +167,17 @@ impl<T: Config> SignedSubmissions<T> {
 	}
 
 	/// Get the submission at a particular index.
-	fn get_submission(&self, idx: u32) -> Option<SignedSubmissionOf<T>> {
-		if self.deletion_overlay.contains(&idx) {
+	fn get_submission(&self, index: u32) -> Option<SignedSubmissionOf<T>> {
+		if self.deletion_overlay.contains(&index) {
 			// Note: can't actually remove the item from the insertion overlay (if present)
 			// because we don't want to use `&mut self` here. There may be some kind of
 			// `RefCell` optimization possible here in the future.
 			None
 		} else {
 			self.insertion_overlay
-				.get(&idx)
+				.get(&index)
 				.cloned()
-				.or_else(|| SignedSubmissionsMap::<T>::try_get(idx).ok())
+				.or_else(|| SignedSubmissionsMap::<T>::get(index))
 		}
 	}
 
@@ -200,18 +200,18 @@ impl<T: Config> SignedSubmissions<T> {
 		remove_score: ElectionScore,
 		insert: Option<(ElectionScore, u32)>,
 	) -> Option<SignedSubmissionOf<T>> {
-		let remove_idx = self.indices.remove(&remove_score)?;
+		let remove_index = self.indices.remove(&remove_score)?;
 		if let Some((insert_score, insert_idx)) = insert {
 			self.indices
 				.try_insert(insert_score, insert_idx)
 				.expect("just removed an item, we must be under capacity; qed");
 		}
 
-		self.insertion_overlay.remove(&remove_idx).or_else(|| {
-			(!self.deletion_overlay.contains(&remove_idx))
+		self.insertion_overlay.remove(&remove_index).or_else(|| {
+			(!self.deletion_overlay.contains(&remove_index))
 				.then(|| {
-					self.deletion_overlay.insert(remove_idx);
-					SignedSubmissionsMap::<T>::try_get(remove_idx).ok()
+					self.deletion_overlay.insert(remove_index);
+					SignedSubmissionsMap::<T>::get(remove_index)
 				})
 				.flatten()
 		})

substrate/frame/elections-phragmen/src/lib.rs

@@ -147,7 +147,7 @@ pub enum Renouncing {
 }
 
 /// An active voter.
-#[derive(Encode, Decode, Clone, Default, RuntimeDebug, PartialEq, TypeInfo)]
+#[derive(Encode, Decode, Clone, RuntimeDebug, PartialEq, TypeInfo)]
 pub struct Voter<AccountId, Balance> {
 	/// The members being backed.
 	pub votes: Vec<AccountId>,
@@ -159,6 +159,12 @@ pub struct Voter<AccountId, Balance> {
 	pub deposit: Balance,
 }
 
+impl<AccountId, Balance: Default> Default for Voter<AccountId, Balance> {
+	fn default() -> Self {
+		Self { votes: vec![], stake: Default::default(), deposit: Default::default() }
+	}
+}
+
 /// A holder of a seat as either a member or a runner-up.
 #[derive(Encode, Decode, Clone, Default, RuntimeDebug, PartialEq, TypeInfo)]
 pub struct SeatHolder<AccountId, Balance> {
@@ -1087,7 +1093,14 @@ impl<T: Config> SortedMembers<T::AccountId> for Pallet<T> {
 	fn add(who: &T::AccountId) {
 		Members::<T>::mutate(|members| match members.binary_search_by(|m| m.who.cmp(who)) {
 			Ok(_) => (),
-			Err(pos) => members.insert(pos, SeatHolder { who: who.clone(), ..Default::default() }),
+			Err(pos) => {
+				let s = SeatHolder {
+					who: who.clone(),
+					stake: Default::default(),
+					deposit: Default::default(),
+				};
+				members.insert(pos, s)
+			},
 		})
 	}
 }

substrate/frame/elections/Cargo.toml

@@ -1,42 +0,0 @@
-[package]
-name = "pallet-elections"
-version = "4.0.0-dev"
-authors = ["Parity Technologies <admin@parity.io>"]
-edition = "2021"
-license = "Apache-2.0"
-homepage = "https://substrate.io"
-repository = "https://github.com/paritytech/substrate/"
-description = "FRAME pallet for elections"
-readme = "README.md"
-
-[package.metadata.docs.rs]
-targets = ["x86_64-unknown-linux-gnu"]
-
-[dependencies]
-codec = { package = "parity-scale-codec", version = "2.0.0", default-features = false, features = [
-	"derive",
-] }
-scale-info = { version = "1.0", default-features = false, features = ["derive"] }
-sp-core = { version = "4.1.0-dev", default-features = false, path = "../../primitives/core" }
-sp-std = { version = "4.0.0", default-features = false, path = "../../primitives/std" }
-sp-io = { version = "4.0.0-dev", default-features = false, path = "../../primitives/io" }
-sp-runtime = { version = "4.0.0-dev", default-features = false, path = "../../primitives/runtime" }
-frame-support = { version = "4.0.0-dev", default-features = false, path = "../support" }
-frame-system = { version = "4.0.0-dev", default-features = false, path = "../system" }
-
-[dev-dependencies]
-pallet-balances = { version = "4.0.0-dev", path = "../balances" }
-
-[features]
-default = ["std"]
-std = [
-	"codec/std",
-	"scale-info/std",
-	"sp-core/std",
-	"sp-std/std",
-	"sp-io/std",
-	"frame-support/std",
-	"sp-runtime/std",
-	"frame-system/std",
-]
-try-runtime = ["frame-support/try-runtime"]

substrate/frame/elections/README.md

@@ -1,7 +0,0 @@
-Election module for stake-weighted membership selection of a collective.
-
-The composition of a set of account IDs works according to one or more approval votes
-weighted by stake. There is a partial carry-over facility to give greater weight to those
-whose voting is serially unsuccessful.
-
-License: Apache-2.0

substrate/frame/elections/src/mock.rs

@@ -1,274 +0,0 @@
-// This file is part of Substrate.
-
-// Copyright (C) 2019-2021 Parity Technologies (UK) Ltd.
-// SPDX-License-Identifier: Apache-2.0
-
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// 	http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-//! Mock file for election module.
-
-#![cfg(test)]
-
-use crate as elections;
-use frame_support::{
-	assert_ok, parameter_types,
-	traits::{ChangeMembers, Currency, LockIdentifier},
-};
-use sp_core::H256;
-use sp_runtime::{
-	testing::Header,
-	traits::{BlakeTwo256, IdentityLookup},
-	BuildStorage,
-};
-
-parameter_types! {
-	pub const BlockHashCount: u64 = 250;
-	pub BlockWeights: frame_system::limits::BlockWeights =
-		frame_system::limits::BlockWeights::simple_max(1024);
-}
-impl frame_system::Config for Test {
-	type BaseCallFilter = frame_support::traits::Everything;
-	type BlockWeights = ();
-	type BlockLength = ();
-	type DbWeight = ();
-	type Origin = Origin;
-	type Call = Call;
-	type Index = u64;
-	type BlockNumber = u64;
-	type Hash = H256;
-	type Hashing = BlakeTwo256;
-	type AccountId = u64;
-	type Lookup = IdentityLookup<Self::AccountId>;
-	type Header = Header;
-	type Event = Event;
-	type BlockHashCount = BlockHashCount;
-	type Version = ();
-	type PalletInfo = PalletInfo;
-	type AccountData = pallet_balances::AccountData<u64>;
-	type OnNewAccount = ();
-	type OnKilledAccount = ();
-	type SystemWeightInfo = ();
-	type SS58Prefix = ();
-	type OnSetCode = ();
-	type MaxConsumers = frame_support::traits::ConstU32<16>;
-}
-
-parameter_types! {
-	pub const ExistentialDeposit: u64 = 1;
-}
-impl pallet_balances::Config for Test {
-	type MaxLocks = ();
-	type MaxReserves = ();
-	type ReserveIdentifier = [u8; 8];
-	type Balance = u64;
-	type DustRemoval = ();
-	type Event = Event;
-	type ExistentialDeposit = ExistentialDeposit;
-	type AccountStore = System;
-	type WeightInfo = ();
-}
-
-parameter_types! {
-	pub const CandidacyBond: u64 = 3;
-	pub const CarryCount: u32 = 2;
-	pub const InactiveGracePeriod: u32 = 1;
-	pub const VotingPeriod: u64 = 4;
-	pub const MinimumVotingLock: u64 = 5;
-	pub static VotingBond: u64 = 0;
-	pub static VotingFee: u64 = 0;
-	pub static PresentSlashPerVoter: u64 = 0;
-	pub static DecayRatio: u32 = 0;
-	pub static Members: Vec<u64> = vec![];
-}
-
-pub struct TestChangeMembers;
-impl ChangeMembers<u64> for TestChangeMembers {
-	fn change_members_sorted(incoming: &[u64], outgoing: &[u64], new: &[u64]) {
-		let mut old_plus_incoming = MEMBERS.with(|m| m.borrow().to_vec());
-		old_plus_incoming.extend_from_slice(incoming);
-		old_plus_incoming.sort();
-		let mut new_plus_outgoing = new.to_vec();
-		new_plus_outgoing.extend_from_slice(outgoing);
-		new_plus_outgoing.sort();
-		assert_eq!(old_plus_incoming, new_plus_outgoing);
-
-		MEMBERS.with(|m| *m.borrow_mut() = new.to_vec());
-	}
-}
-
-parameter_types! {
-	pub const ElectionPalletId: LockIdentifier = *b"py/elect";
-}
-
-impl elections::Config for Test {
-	type Event = Event;
-	type Currency = Balances;
-	type BadPresentation = ();
-	type BadReaper = ();
-	type BadVoterIndex = ();
-	type LoserCandidate = ();
-	type ChangeMembers = TestChangeMembers;
-	type CandidacyBond = CandidacyBond;
-	type VotingBond = VotingBond;
-	type VotingFee = VotingFee;
-	type MinimumVotingLock = MinimumVotingLock;
-	type PresentSlashPerVoter = PresentSlashPerVoter;
-	type CarryCount = CarryCount;
-	type InactiveGracePeriod = InactiveGracePeriod;
-	type VotingPeriod = VotingPeriod;
-	type DecayRatio = DecayRatio;
-	type PalletId = ElectionPalletId;
-}
-
-pub type Block = sp_runtime::generic::Block<Header, UncheckedExtrinsic>;
-pub type UncheckedExtrinsic = sp_runtime::generic::UncheckedExtrinsic<u32, u64, Call, ()>;
-
-use frame_system as system;
-frame_support::construct_runtime!(
-	pub enum Test where
-		Block = Block,
-		NodeBlock = Block,
-		UncheckedExtrinsic = UncheckedExtrinsic
-	{
-		System: system::{Pallet, Call, Event<T>},
-		Balances: pallet_balances::{Pallet, Call, Event<T>, Config<T>},
-		Elections: elections::{Pallet, Call, Event<T>, Config<T>},
-	}
-);
-
-pub struct ExtBuilder {
-	balance_factor: u64,
-	decay_ratio: u32,
-	desired_seats: u32,
-	voting_fee: u64,
-	voting_bond: u64,
-	bad_presentation_punishment: u64,
-}
-
-impl Default for ExtBuilder {
-	fn default() -> Self {
-		Self {
-			balance_factor: 1,
-			decay_ratio: 24,
-			desired_seats: 2,
-			voting_fee: 0,
-			voting_bond: 0,
-			bad_presentation_punishment: 1,
-		}
-	}
-}
-
-impl ExtBuilder {
-	pub fn balance_factor(mut self, factor: u64) -> Self {
-		self.balance_factor = factor;
-		self
-	}
-	pub fn decay_ratio(mut self, ratio: u32) -> Self {
-		self.decay_ratio = ratio;
-		self
-	}
-	pub fn voting_fee(mut self, fee: u64) -> Self {
-		self.voting_fee = fee;
-		self
-	}
-	pub fn bad_presentation_punishment(mut self, fee: u64) -> Self {
-		self.bad_presentation_punishment = fee;
-		self
-	}
-	pub fn voting_bond(mut self, fee: u64) -> Self {
-		self.voting_bond = fee;
-		self
-	}
-	pub fn desired_seats(mut self, seats: u32) -> Self {
-		self.desired_seats = seats;
-		self
-	}
-	pub fn build(self) -> sp_io::TestExternalities {
-		VOTING_BOND.with(|v| *v.borrow_mut() = self.voting_bond);
-		VOTING_FEE.with(|v| *v.borrow_mut() = self.voting_fee);
-		PRESENT_SLASH_PER_VOTER.with(|v| *v.borrow_mut() = self.bad_presentation_punishment);
-		DECAY_RATIO.with(|v| *v.borrow_mut() = self.decay_ratio);
-		let mut ext: sp_io::TestExternalities = GenesisConfig {
-			balances: pallet_balances::GenesisConfig::<Test> {
-				balances: vec![
-					(1, 10 * self.balance_factor),
-					(2, 20 * self.balance_factor),
-					(3, 30 * self.balance_factor),
-					(4, 40 * self.balance_factor),
-					(5, 50 * self.balance_factor),
-					(6, 60 * self.balance_factor),
-				],
-			},
-			elections: elections::GenesisConfig::<Test> {
-				members: vec![],
-				desired_seats: self.desired_seats,
-				presentation_duration: 2,
-				term_duration: 5,
-			},
-		}
-		.build_storage()
-		.unwrap()
-		.into();
-		ext.execute_with(|| System::set_block_number(1));
-		ext
-	}
-}
-
-pub(crate) fn voter_ids() -> Vec<u64> {
-	Elections::all_voters().iter().map(|v| v.unwrap_or(0)).collect::<Vec<u64>>()
-}
-
-pub(crate) fn vote(i: u64, l: usize) {
-	let _ = Balances::make_free_balance_be(&i, 20);
-	assert_ok!(Elections::set_approvals(
-		Origin::signed(i),
-		(0..l).map(|_| true).collect::<Vec<bool>>(),
-		0,
-		0,
-		20,
-	));
-}
-
-pub(crate) fn vote_at(i: u64, l: usize, index: elections::VoteIndex) {
-	let _ = Balances::make_free_balance_be(&i, 20);
-	assert_ok!(Elections::set_approvals(
-		Origin::signed(i),
-		(0..l).map(|_| true).collect::<Vec<bool>>(),
-		0,
-		index,
-		20,
-	));
-}
-
-pub(crate) fn create_candidate(i: u64, index: u32) {
-	let _ = Balances::make_free_balance_be(&i, 20);
-	assert_ok!(Elections::submit_candidacy(Origin::signed(i), index));
-}
-
-pub(crate) fn balances(who: &u64) -> (u64, u64) {
-	(Balances::free_balance(who), Balances::reserved_balance(who))
-}
-
-pub(crate) fn locks(who: &u64) -> Vec<u64> {
-	Balances::locks(who).iter().map(|l| l.amount).collect::<Vec<u64>>()
-}
-
-pub(crate) fn new_test_ext_with_candidate_holes() -> sp_io::TestExternalities {
-	let mut t = ExtBuilder::default().build();
-	t.execute_with(|| {
-		<elections::Candidates<Test>>::put(vec![0, 0, 1]);
-		elections::CandidateCount::<Test>::put(1);
-		<elections::RegisterInfoOf<Test>>::insert(1, (0, 2));
-	});
-	t
-}

substrate/frame/examples/basic/src/lib.rs

@@ -731,6 +731,16 @@ where
 		Ok(())
 	}
 
+	fn pre_dispatch(
+		self,
+		who: &Self::AccountId,
+		call: &Self::Call,
+		info: &DispatchInfoOf<Self::Call>,
+		len: usize,
+	) -> Result<Self::Pre, TransactionValidityError> {
+		Ok(self.validate(who, call, info, len).map(|_| ())?)
+	}
+
 	fn validate(
 		&self,
 		_who: &Self::AccountId,

substrate/frame/examples/offchain-worker/src/lib.rs

@@ -233,7 +233,7 @@ pub mod pallet {
 			// Retrieve sender of the transaction.
 			let who = ensure_signed(origin)?;
 			// Add the price to the on-chain list.
-			Self::add_price(who, price);
+			Self::add_price(Some(who), price);
 			Ok(().into())
 		}
 
@@ -262,7 +262,7 @@ pub mod pallet {
 			// This ensures that the function can only be called via unsigned transaction.
 			ensure_none(origin)?;
 			// Add the price to the on-chain list, but mark it as coming from an empty address.
-			Self::add_price(Default::default(), price);
+			Self::add_price(None, price);
 			// now increment the block number at which we expect next unsigned transaction.
 			let current_block = <system::Pallet<T>>::block_number();
 			<NextUnsignedAt<T>>::put(current_block + T::UnsignedInterval::get());
@@ -278,7 +278,7 @@ pub mod pallet {
 			// This ensures that the function can only be called via unsigned transaction.
 			ensure_none(origin)?;
 			// Add the price to the on-chain list, but mark it as coming from an empty address.
-			Self::add_price(Default::default(), price_payload.price);
+			Self::add_price(None, price_payload.price);
 			// now increment the block number at which we expect next unsigned transaction.
 			let current_block = <system::Pallet<T>>::block_number();
 			<NextUnsignedAt<T>>::put(current_block + T::UnsignedInterval::get());
@@ -291,7 +291,7 @@ pub mod pallet {
 	#[pallet::generate_deposit(pub(super) fn deposit_event)]
 	pub enum Event<T: Config> {
 		/// Event generated when new price is accepted to contribute to the average.
-		NewPrice { price: u32, who: T::AccountId },
+		NewPrice { price: u32, maybe_who: Option<T::AccountId> },
 	}
 
 	#[pallet::validate_unsigned]
@@ -641,7 +641,7 @@ impl<T: Config> Pallet<T> {
 	}
 
 	/// Add new price to the list.
-	fn add_price(who: T::AccountId, price: u32) {
+	fn add_price(maybe_who: Option<T::AccountId>, price: u32) {
 		log::info!("Adding to the average: {}", price);
 		<Prices<T>>::mutate(|prices| {
 			const MAX_LEN: usize = 64;
@@ -657,7 +657,7 @@ impl<T: Config> Pallet<T> {
 			.expect("The average is not empty, because it was just mutated; qed");
 		log::info!("Current average price is: {}", average);
 		// here we are raising the NewPrice event
-		Self::deposit_event(Event::NewPrice { price, who });
+		Self::deposit_event(Event::NewPrice { price, maybe_who });
 	}
 
 	/// Calculate current average price.

substrate/frame/examples/offchain-worker/src/tests.rs

@@ -125,15 +125,19 @@ impl Config for Test {
 	type UnsignedPriority = UnsignedPriority;
 }
 
+fn test_pub() -> sp_core::sr25519::Public {
+	sp_core::sr25519::Public::from_raw([1u8; 32])
+}
+
 #[test]
 fn it_aggregates_the_price() {
 	sp_io::TestExternalities::default().execute_with(|| {
 		assert_eq!(Example::average_price(), None);
 
-		assert_ok!(Example::submit_price(Origin::signed(Default::default()), 27));
+		assert_ok!(Example::submit_price(Origin::signed(test_pub()), 27));
 		assert_eq!(Example::average_price(), Some(27));
 
-		assert_ok!(Example::submit_price(Origin::signed(Default::default()), 43));
+		assert_ok!(Example::submit_price(Origin::signed(test_pub()), 43));
 		assert_eq!(Example::average_price(), Some(35));
 	});
 }

substrate/frame/examples/parallel/src/lib.rs

@@ -105,13 +105,13 @@ pub struct EnlistedParticipant {
 
 impl EnlistedParticipant {
 	fn verify(&self, event_id: &[u8]) -> bool {
-		use sp_core::Public;
+		use sp_core::ByteArray;
 		use sp_runtime::traits::Verify;
 
 		match sp_core::sr25519::Signature::try_from(&self.signature[..]) {
-			Ok(signature) => {
-				let public = sp_core::sr25519::Public::from_slice(self.account.as_ref());
-				signature.verify(event_id, &public)
+			Ok(signature) => match sp_core::sr25519::Public::from_slice(self.account.as_ref()) {
+				Err(()) => false,
+				Ok(signer) => signature.verify(event_id, &signer),
 			},
 			_ => false,
 		}

substrate/frame/examples/parallel/src/tests.rs

@@ -81,6 +81,14 @@ impl Config for Test {
 	type Call = Call;
 }
 
+fn test_pub(n: u8) -> sp_core::sr25519::Public {
+	sp_core::sr25519::Public::from_raw([n; 32])
+}
+
+fn test_origin(n: u8) -> Origin {
+	Origin::signed(test_pub(n))
+}
+
 #[test]
 fn it_can_enlist() {
 	use sp_core::Pair;
@@ -91,8 +99,7 @@ fn it_can_enlist() {
 
 		let event_name = b"test";
 
-		Example::run_event(Origin::signed(Default::default()), event_name.to_vec())
-			.expect("Failed to enlist");
+		Example::run_event(test_origin(1), event_name.to_vec()).expect("Failed to enlist");
 
 		let participants = vec![
 			EnlistedParticipant {
@@ -105,7 +112,7 @@ fn it_can_enlist() {
 			},
 		];
 
-		Example::enlist_participants(Origin::signed(Default::default()), participants)
+		Example::enlist_participants(Origin::signed(test_pub(1)), participants)
 			.expect("Failed to enlist");
 
 		assert_eq!(Example::participants().len(), 2);
@@ -123,8 +130,7 @@ fn one_wrong_will_not_enlist_anyone() {
 
 		let event_name = b"test";
 
-		Example::run_event(Origin::signed(Default::default()), event_name.to_vec())
-			.expect("Failed to enlist");
+		Example::run_event(test_origin(1), event_name.to_vec()).expect("Failed to enlist");
 
 		let participants = vec![
 			EnlistedParticipant {
@@ -142,8 +148,7 @@ fn one_wrong_will_not_enlist_anyone() {
 			},
 		];
 
-		Example::enlist_participants(Origin::signed(Default::default()), participants)
-			.expect("Failed to enlist");
+		Example::enlist_participants(test_origin(1), participants).expect("Failed to enlist");
 
 		assert_eq!(Example::participants().len(), 0);
 	});

substrate/frame/grandpa/src/equivocation.rs

@@ -185,7 +185,7 @@ where
 	}
 
 	fn block_author() -> Option<T::AccountId> {
-		Some(<pallet_authorship::Pallet<T>>::author())
+		<pallet_authorship::Pallet<T>>::author()
 	}
 }
 

substrate/frame/im-online/src/lib.rs

@@ -324,7 +324,6 @@ pub mod pallet {
 		type AuthorityId: Member
 			+ Parameter
 			+ RuntimeAppPublic
-			+ Default
 			+ Ord
 			+ MaybeSerializeDeserialize
 			+ MaxEncodedLen;

substrate/frame/im-online/src/mock.rs

@@ -106,7 +106,15 @@ impl ReportOffence<u64, IdentificationTuple, Offence> for OffenceHandler {
 
 pub fn new_test_ext() -> sp_io::TestExternalities {
 	let t = frame_system::GenesisConfig::default().build_storage::<Runtime>().unwrap();
-	t.into()
+	let mut result: sp_io::TestExternalities = t.into();
+	// Set the default keys, otherwise session will discard the validator.
+	result.execute_with(|| {
+		for i in 1..=6 {
+			System::inc_providers(&i);
+			assert_eq!(Session::set_keys(Origin::signed(i), (i - 1).into(), vec![]), Ok(()));
+		}
+	});
+	result
 }
 
 parameter_types! {

substrate/frame/multisig/src/lib.rs

@@ -64,7 +64,7 @@ use frame_system::{self as system, RawOrigin};
 use scale_info::TypeInfo;
 use sp_io::hashing::blake2_256;
 use sp_runtime::{
-	traits::{Dispatchable, Zero},
+	traits::{Dispatchable, TrailingZeroInput, Zero},
 	DispatchError,
 };
 use sp_std::prelude::*;
@@ -508,7 +508,8 @@ impl<T: Config> Pallet<T> {
 	/// NOTE: `who` must be sorted. If it is not, then you'll get the wrong answer.
 	pub fn multi_account_id(who: &[T::AccountId], threshold: u16) -> T::AccountId {
 		let entropy = (b"modlpy/utilisuba", who, threshold).using_encoded(blake2_256);
-		T::AccountId::decode(&mut &entropy[..]).unwrap_or_default()
+		Decode::decode(&mut TrailingZeroInput::new(entropy.as_ref()))
+			.expect("infinite length input; no invalid inputs for type; qed")
 	}
 
 	fn operate(

substrate/frame/proxy/src/lib.rs

@@ -45,7 +45,7 @@ use frame_system::{self as system};
 use scale_info::TypeInfo;
 use sp_io::hashing::blake2_256;
 use sp_runtime::{
-	traits::{Dispatchable, Hash, Saturating, Zero},
+	traits::{Dispatchable, Hash, Saturating, TrailingZeroInput, Zero},
 	DispatchResult,
 };
 use sp_std::{convert::TryInto, prelude::*};
@@ -653,7 +653,8 @@ impl<T: Config> Pallet<T> {
 		});
 		let entropy = (b"modlpy/proxy____", who, height, ext_index, proxy_type, index)
 			.using_encoded(blake2_256);
-		T::AccountId::decode(&mut &entropy[..]).unwrap_or_default()
+		Decode::decode(&mut TrailingZeroInput::new(entropy.as_ref()))
+			.expect("infinite length input; no invalid inputs for type; qed")
 	}
 
 	/// Register a proxy account for the delegator that is able to make calls on its behalf.

substrate/frame/session/benchmarking/src/lib.rs

@@ -22,7 +22,7 @@
 
 mod mock;
 
-use sp_runtime::traits::{One, StaticLookup};
+use sp_runtime::traits::{One, StaticLookup, TrailingZeroInput};
 use sp_std::{prelude::*, vec};
 
 use frame_benchmarking::benchmarks;
@@ -61,7 +61,8 @@ benchmarks! {
 			RewardDestination::Staked,
 		)?;
 		let v_controller = pallet_staking::Pallet::<T>::bonded(&v_stash).ok_or("not stash")?;
-		let keys = T::Keys::default();
+
+		let keys = T::Keys::decode(&mut TrailingZeroInput::zeroes()).unwrap();
 		let proof: Vec<u8> = vec![0,1,2,3];
 		// Whitelist controller account from further DB operations.
 		let v_controller_key = frame_system::Account::<T>::hashed_key_for(&v_controller);
@@ -77,7 +78,7 @@ benchmarks! {
 			RewardDestination::Staked
 		)?;
 		let v_controller = pallet_staking::Pallet::<T>::bonded(&v_stash).ok_or("not stash")?;
-		let keys = T::Keys::default();
+		let keys = T::Keys::decode(&mut TrailingZeroInput::zeroes()).unwrap();
 		let proof: Vec<u8> = vec![0,1,2,3];
 		Session::<T>::set_keys(RawOrigin::Signed(v_controller.clone()).into(), keys, proof)?;
 		// Whitelist controller account from further DB operations.

substrate/frame/session/src/lib.rs

@@ -312,8 +312,10 @@ impl<AId> SessionHandler<AId> for Tuple {
 		for_tuples!(
 			#(
 				let our_keys: Box<dyn Iterator<Item=_>> = Box::new(validators.iter()
-					.map(|k| (&k.0, k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID)
-						.unwrap_or_default())));
+					.filter_map(|k|
+						k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID).map(|k1| (&k.0, k1))
+					)
+				);
 
 				Tuple::on_genesis_session(our_keys);
 			)*
@@ -328,11 +330,13 @@ impl<AId> SessionHandler<AId> for Tuple {
 		for_tuples!(
 			#(
 				let our_keys: Box<dyn Iterator<Item=_>> = Box::new(validators.iter()
-					.map(|k| (&k.0, k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID)
-						.unwrap_or_default())));
+					.filter_map(|k|
+						k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID).map(|k1| (&k.0, k1))
+					));
 				let queued_keys: Box<dyn Iterator<Item=_>> = Box::new(queued_validators.iter()
-					.map(|k| (&k.0, k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID)
-						.unwrap_or_default())));
+					.filter_map(|k|
+						k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID).map(|k1| (&k.0, k1))
+					));
 				Tuple::on_new_session(changed, our_keys, queued_keys);
 			)*
 		)
@@ -403,7 +407,7 @@ pub mod pallet {
 		type SessionHandler: SessionHandler<Self::ValidatorId>;
 
 		/// The keys.
-		type Keys: OpaqueKeys + Member + Parameter + Default + MaybeSerializeDeserialize;
+		type Keys: OpaqueKeys + Member + Parameter + MaybeSerializeDeserialize;
 
 		/// Weight information for extrinsics in this pallet.
 		type WeightInfo: WeightInfo;
@@ -476,13 +480,18 @@ pub mod pallet {
 			let queued_keys: Vec<_> = initial_validators_1
 				.iter()
 				.cloned()
-				.map(|v| (v.clone(), <Pallet<T>>::load_keys(&v).unwrap_or_default()))
+				.filter_map(|v| {
+					Some((
+						v.clone(),
+						Pallet::<T>::load_keys(&v).expect("Validator in session 1 missing keys!"),
+					))
+				})
 				.collect();
 
 			// Tell everyone about the genesis session keys
 			T::SessionHandler::on_genesis_session::<T::Keys>(&queued_keys);
 
-			<Validators<T>>::put(initial_validators_0);
+			Validators::<T>::put(initial_validators_0);
 			<QueuedKeys<T>>::put(queued_keys);
 
 			T::SessionManager::start_session(0);
@@ -641,7 +650,7 @@ impl<T: Config> Pallet<T> {
 		let session_keys = <QueuedKeys<T>>::get();
 		let validators =
 			session_keys.iter().map(|(validator, _)| validator.clone()).collect::<Vec<_>>();
-		<Validators<T>>::put(&validators);
+		Validators::<T>::put(&validators);
 
 		if changed {
 			// reset disabled validators
@@ -663,7 +672,7 @@ impl<T: Config> Pallet<T> {
 				// same as before, as underlying economic conditions may have changed.
 				(validators, true)
 			} else {
-				(<Validators<T>>::get(), false)
+				(Validators::<T>::get(), false)
 			};
 
 		// Queue next session keys.
@@ -689,10 +698,10 @@ impl<T: Config> Pallet<T> {
 			};
 			let queued_amalgamated = next_validators
 				.into_iter()
-				.map(|a| {
-					let k = Self::load_keys(&a).unwrap_or_default();
+				.filter_map(|a| {
+					let k = Self::load_keys(&a)?;
 					check_next_changed(&k);
-					(a, k)
+					Some((a, k))
 				})
 				.collect::<Vec<_>>();
 

substrate/frame/staking/src/benchmarking.rs

@@ -21,6 +21,7 @@ use super::*;
 use crate::Pallet as Staking;
 use testing_utils::*;
 
+use codec::Decode;
 use frame_election_provider_support::SortedListProvider;
 use frame_support::{
 	dispatch::UnfilteredDispatchable,
@@ -28,7 +29,7 @@ use frame_support::{
 	traits::{Currency, CurrencyToVote, Get, Imbalance},
 };
 use sp_runtime::{
-	traits::{Bounded, One, StaticLookup, Zero},
+	traits::{Bounded, One, StaticLookup, TrailingZeroInput, Zero},
 	Perbill, Percent,
 };
 use sp_staking::SessionIndex;
@@ -535,8 +536,9 @@ benchmarks! {
 		let s in 1 .. MAX_SLASHES;
 		let mut unapplied_slashes = Vec::new();
 		let era = EraIndex::one();
+		let dummy = || T::AccountId::decode(&mut TrailingZeroInput::zeroes()).unwrap();
 		for _ in 0 .. MAX_SLASHES {
-			unapplied_slashes.push(UnappliedSlash::<T::AccountId, BalanceOf<T>>::default());
+			unapplied_slashes.push(UnappliedSlash::<T::AccountId, BalanceOf<T>>::default_from(dummy()));
 		}
 		UnappliedSlashes::<T>::insert(era, &unapplied_slashes);
 
@@ -667,10 +669,11 @@ benchmarks! {
 		let e in 1 .. 100;
 		HistoryDepth::<T>::put(e);
 		CurrentEra::<T>::put(e);
+		let dummy = || -> T::AccountId { codec::Decode::decode(&mut TrailingZeroInput::zeroes()).unwrap() };
 		for i in 0 .. e {
-			<ErasStakers<T>>::insert(i, T::AccountId::default(), Exposure::<T::AccountId, BalanceOf<T>>::default());
-			<ErasStakersClipped<T>>::insert(i, T::AccountId::default(), Exposure::<T::AccountId, BalanceOf<T>>::default());
-			<ErasValidatorPrefs<T>>::insert(i, T::AccountId::default(), ValidatorPrefs::default());
+			<ErasStakers<T>>::insert(i, dummy(), Exposure::<T::AccountId, BalanceOf<T>>::default());
+			<ErasStakersClipped<T>>::insert(i, dummy(), Exposure::<T::AccountId, BalanceOf<T>>::default());
+			<ErasValidatorPrefs<T>>::insert(i, dummy(), ValidatorPrefs::default());
 			<ErasValidatorReward<T>>::insert(i, BalanceOf::<T>::one());
 			<ErasRewardPoints<T>>::insert(i, EraRewardPoints::<T::AccountId>::default());
 			<ErasTotalStake<T>>::insert(i, BalanceOf::<T>::one());
@@ -695,7 +698,14 @@ benchmarks! {
 		let stash = scenario.origin_stash1.clone();
 
 		add_slashing_spans::<T>(&stash, s);
-		Ledger::<T>::insert(&controller, StakingLedger { active: T::Currency::minimum_balance() - One::one(), total: T::Currency::minimum_balance() - One::one(), ..Default::default() });
+		let l = StakingLedger {
+			stash: stash.clone(),
+			active: T::Currency::minimum_balance() - One::one(),
+			total: T::Currency::minimum_balance() - One::one(),
+			unlocking: vec![],
+			claimed_rewards: vec![],
+		};
+		Ledger::<T>::insert(&controller, l);
 
 		assert!(Bonded::<T>::contains_key(&stash));
 		assert!(T::SortedListProvider::contains(&stash));

substrate/frame/staking/src/lib.rs

@@ -364,7 +364,7 @@ pub struct ActiveEraInfo {
 /// Reward points of an era. Used to split era total payout between validators.
 ///
 /// This points will be used to reward validators and their respective nominators.
-#[derive(PartialEq, Encode, Decode, Default, RuntimeDebug, TypeInfo)]
+#[derive(PartialEq, Encode, Decode, RuntimeDebug, TypeInfo)]
 pub struct EraRewardPoints<AccountId: Ord> {
 	/// Total number of points. Equals the sum of reward points for each validator.
 	total: RewardPoint,
@@ -372,9 +372,15 @@ pub struct EraRewardPoints<AccountId: Ord> {
 	individual: BTreeMap<AccountId, RewardPoint>,
 }
 
+impl<AccountId: Ord> Default for EraRewardPoints<AccountId> {
+	fn default() -> Self {
+		EraRewardPoints { total: Default::default(), individual: BTreeMap::new() }
+	}
+}
+
 /// Indicates the initial status of the staker.
 #[derive(RuntimeDebug, TypeInfo)]
-#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize, Clone))]
 pub enum StakerStatus<AccountId> {
 	/// Chilling.
 	Idle,
@@ -436,7 +442,6 @@ pub struct UnlockChunk<Balance: HasCompact> {
 }
 
 /// The ledger of a (bonded) stash.
-#[cfg_attr(feature = "runtime-benchmarks", derive(Default))]
 #[derive(PartialEq, Eq, Clone, Encode, Decode, RuntimeDebug, TypeInfo)]
 pub struct StakingLedger<AccountId, Balance: HasCompact> {
 	/// The stash account whose balance is actually locked and at stake.
@@ -457,9 +462,20 @@ pub struct StakingLedger<AccountId, Balance: HasCompact> {
 	pub claimed_rewards: Vec<EraIndex>,
 }
 
-impl<AccountId, Balance: HasCompact + Copy + Saturating + AtLeast32BitUnsigned>
+impl<AccountId, Balance: HasCompact + Copy + Saturating + AtLeast32BitUnsigned + Zero>
 	StakingLedger<AccountId, Balance>
 {
+	/// Initializes the default object using the given `validator`.
+	pub fn default_from(stash: AccountId) -> Self {
+		Self {
+			stash,
+			total: Zero::zero(),
+			active: Zero::zero(),
+			unlocking: vec![],
+			claimed_rewards: vec![],
+		}
+	}
+
 	/// Remove entries from `unlocking` that are sufficiently old and reduce the
 	/// total by the sum of their balances.
 	fn consolidate_unlocked(self, current_era: EraIndex) -> Self {
@@ -593,9 +609,7 @@ pub struct IndividualExposure<AccountId, Balance: HasCompact> {
 }
 
 /// A snapshot of the stake backing a single validator in the system.
-#[derive(
-	PartialEq, Eq, PartialOrd, Ord, Clone, Encode, Decode, Default, RuntimeDebug, TypeInfo,
-)]
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Encode, Decode, RuntimeDebug, TypeInfo)]
 pub struct Exposure<AccountId, Balance: HasCompact> {
 	/// The total balance backing this validator.
 	#[codec(compact)]
@@ -607,9 +621,15 @@ pub struct Exposure<AccountId, Balance: HasCompact> {
 	pub others: Vec<IndividualExposure<AccountId, Balance>>,
 }
 
+impl<AccountId, Balance: Default + HasCompact> Default for Exposure<AccountId, Balance> {
+	fn default() -> Self {
+		Self { total: Default::default(), own: Default::default(), others: vec![] }
+	}
+}
+
 /// A pending slash record. The value of the slash has been computed but not applied yet,
 /// rather deferred for several eras.
-#[derive(Encode, Decode, Default, RuntimeDebug, TypeInfo)]
+#[derive(Encode, Decode, RuntimeDebug, TypeInfo)]
 pub struct UnappliedSlash<AccountId, Balance: HasCompact> {
 	/// The stash ID of the offending validator.
 	validator: AccountId,
@@ -623,6 +643,19 @@ pub struct UnappliedSlash<AccountId, Balance: HasCompact> {
 	payout: Balance,
 }
 
+impl<AccountId, Balance: HasCompact + Zero> UnappliedSlash<AccountId, Balance> {
+	/// Initializes the default object using the given `validator`.
+	pub fn default_from(validator: AccountId) -> Self {
+		Self {
+			validator,
+			own: Zero::zero(),
+			others: vec![],
+			reporters: vec![],
+			payout: Zero::zero(),
+		}
+	}
+}
+
 /// Means for interacting with a specialized version of the `session` trait.
 ///
 /// This is needed because `Staking` sets the `ValidatorIdOf` of the `pallet_session::Config`

substrate/frame/staking/src/mock.rs

@@ -480,7 +480,7 @@ impl ExtBuilder {
 		}
 
 		let _ = pallet_staking::GenesisConfig::<Test> {
-			stakers,
+			stakers: stakers.clone(),
 			validator_count: self.validator_count,
 			minimum_validator_count: self.minimum_validator_count,
 			invulnerables: self.invulnerables,
@@ -493,12 +493,15 @@ impl ExtBuilder {
 
 		let _ = pallet_session::GenesisConfig::<Test> {
 			keys: if self.has_stakers {
-				// genesis election will overwrite this, no worries.
-				Default::default()
+				// set the keys for the first session.
+				stakers
+					.into_iter()
+					.map(|(id, ..)| (id, id, SessionKeys { other: id.into() }))
+					.collect()
 			} else {
 				// set some dummy validators in genesis.
 				(0..self.validator_count as u64)
-					.map(|x| (x, x, SessionKeys { other: UintAuthorityId(x as u64) }))
+					.map(|id| (id, id, SessionKeys { other: id.into() }))
 					.collect()
 			},
 		}
@@ -644,6 +647,7 @@ pub(crate) fn bond(stash: AccountId, ctrl: AccountId, val: Balance) {
 pub(crate) fn bond_validator(stash: AccountId, ctrl: AccountId, val: Balance) {
 	bond(stash, ctrl, val);
 	assert_ok!(Staking::validate(Origin::signed(ctrl), ValidatorPrefs::default()));
+	assert_ok!(Session::set_keys(Origin::signed(ctrl), SessionKeys { other: ctrl.into() }, vec![]));
 }
 
 pub(crate) fn bond_nominator(

substrate/frame/staking/src/pallet/impls.rs

@@ -1089,8 +1089,13 @@ where
 	fn note_author(author: T::AccountId) {
 		Self::reward_by_ids(vec![(author, 20)])
 	}
-	fn note_uncle(author: T::AccountId, _age: T::BlockNumber) {
-		Self::reward_by_ids(vec![(<pallet_authorship::Pallet<T>>::author(), 2), (author, 1)])
+	fn note_uncle(uncle_author: T::AccountId, _age: T::BlockNumber) {
+		// defensive-only: block author must exist.
+		if let Some(block_author) = <pallet_authorship::Pallet<T>>::author() {
+			Self::reward_by_ids(vec![(block_author, 2), (uncle_author, 1)])
+		} else {
+			crate::log!(warn, "block author not set, this should never happen");
+		}
 	}
 }
 
@@ -1238,8 +1243,13 @@ impl<T: Config> VoteWeightProvider<T::AccountId> for Pallet<T> {
 		// this will clearly results in an inconsistent state, but it should not matter for a
 		// benchmark.
 		let active: BalanceOf<T> = weight.try_into().map_err(|_| ()).unwrap();
-		let mut ledger = Self::ledger(who).unwrap_or_default();
-		ledger.active = active;
+		let ledger = match Self::ledger(who) {
+			None => StakingLedger::default_from(who.clone()),
+			Some(mut l) => {
+				l.active = active;
+				l
+			},
+		};
 		<Ledger<T>>::insert(who, ledger);
 		<Bonded<T>>::insert(who, who);
 

substrate/frame/staking/src/tests.rs

@@ -217,16 +217,17 @@ fn rewards_should_work() {
 		Payee::<Test>::insert(21, RewardDestination::Controller);
 		Payee::<Test>::insert(101, RewardDestination::Controller);
 
-		<Pallet<Test>>::reward_by_ids(vec![(11, 50)]);
-		<Pallet<Test>>::reward_by_ids(vec![(11, 50)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 50)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 50)]);
 		// This is the second validator of the current elected set.
-		<Pallet<Test>>::reward_by_ids(vec![(21, 50)]);
+		Pallet::<Test>::reward_by_ids(vec![(21, 50)]);
 
 		// Compute total payout now for whole duration of the session.
 		let total_payout_0 = current_total_payout_for_duration(reward_time_per_era());
 		let maximum_payout = maximum_payout_for_duration(reward_time_per_era());
 
 		start_session(1);
+		assert_eq_uvec!(Session::validators(), vec![11, 21]);
 
 		assert_eq!(Balances::total_balance(&10), init_balance_10);
 		assert_eq!(Balances::total_balance(&11), init_balance_11);
@@ -234,7 +235,6 @@ fn rewards_should_work() {
 		assert_eq!(Balances::total_balance(&21), init_balance_21);
 		assert_eq!(Balances::total_balance(&100), init_balance_100);
 		assert_eq!(Balances::total_balance(&101), init_balance_101);
-		assert_eq_uvec!(Session::validators(), vec![11, 21]);
 		assert_eq!(
 			Staking::eras_reward_points(active_era()),
 			EraRewardPoints {
@@ -283,7 +283,7 @@ fn rewards_should_work() {
 		assert_eq_error_rate!(Balances::total_balance(&101), init_balance_101, 2);
 
 		assert_eq_uvec!(Session::validators(), vec![11, 21]);
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 
 		// Compute total payout now for whole duration as other parameter won't change
 		let total_payout_1 = current_total_payout_for_duration(reward_time_per_era());
@@ -338,6 +338,7 @@ fn staking_should_work() {
 		// add a new candidate for being a validator. account 3 controlled by 4.
 		assert_ok!(Staking::bond(Origin::signed(3), 4, 1500, RewardDestination::Controller));
 		assert_ok!(Staking::validate(Origin::signed(4), ValidatorPrefs::default()));
+		assert_ok!(Session::set_keys(Origin::signed(4), SessionKeys { other: 4.into() }, vec![]));
 
 		// No effects will be seen so far.
 		assert_eq_uvec!(validator_controllers(), vec![20, 10]);
@@ -519,8 +520,8 @@ fn nominating_and_rewards_should_work() {
 
 			// the total reward for era 0
 			let total_payout_0 = current_total_payout_for_duration(reward_time_per_era());
-			<Pallet<Test>>::reward_by_ids(vec![(41, 1)]);
-			<Pallet<Test>>::reward_by_ids(vec![(21, 1)]);
+			Pallet::<Test>::reward_by_ids(vec![(41, 1)]);
+			Pallet::<Test>::reward_by_ids(vec![(21, 1)]);
 
 			mock::start_active_era(1);
 
@@ -561,8 +562,8 @@ fn nominating_and_rewards_should_work() {
 
 			// the total reward for era 1
 			let total_payout_1 = current_total_payout_for_duration(reward_time_per_era());
-			<Pallet<Test>>::reward_by_ids(vec![(21, 2)]);
-			<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+			Pallet::<Test>::reward_by_ids(vec![(21, 2)]);
+			Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 
 			mock::start_active_era(2);
 
@@ -942,7 +943,7 @@ fn reward_destination_works() {
 
 		// Compute total payout now for whole duration as other parameter won't change
 		let total_payout_0 = current_total_payout_for_duration(reward_time_per_era());
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 
 		mock::start_active_era(1);
 		mock::make_all_reward_payment(0);
@@ -968,7 +969,7 @@ fn reward_destination_works() {
 
 		// Compute total payout now for whole duration as other parameter won't change
 		let total_payout_1 = current_total_payout_for_duration(reward_time_per_era());
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 
 		mock::start_active_era(2);
 		mock::make_all_reward_payment(1);
@@ -999,7 +1000,7 @@ fn reward_destination_works() {
 
 		// Compute total payout now for whole duration as other parameter won't change
 		let total_payout_2 = current_total_payout_for_duration(reward_time_per_era());
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 
 		mock::start_active_era(3);
 		mock::make_all_reward_payment(2);
@@ -1049,7 +1050,7 @@ fn validator_payment_prefs_work() {
 		// Compute total payout now for whole duration as other parameter won't change
 		let total_payout_1 = current_total_payout_for_duration(reward_time_per_era());
 		let exposure_1 = Staking::eras_stakers(active_era(), 11);
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 
 		mock::start_active_era(2);
 		mock::make_all_reward_payment(1);
@@ -1610,8 +1611,8 @@ fn reward_to_stake_works() {
 
 			// Compute total payout now for whole duration as other parameter won't change
 			let total_payout_0 = current_total_payout_for_duration(reward_time_per_era());
-			<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
-			<Pallet<Test>>::reward_by_ids(vec![(21, 1)]);
+			Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
+			Pallet::<Test>::reward_by_ids(vec![(21, 1)]);
 
 			// New era --> rewards are paid --> stakes are changed
 			mock::start_active_era(1);
@@ -1707,6 +1708,7 @@ fn switching_roles() {
 		// add a new validator candidate
 		assert_ok!(Staking::bond(Origin::signed(5), 6, 1000, RewardDestination::Controller));
 		assert_ok!(Staking::validate(Origin::signed(6), ValidatorPrefs::default()));
+		assert_ok!(Session::set_keys(Origin::signed(6), SessionKeys { other: 6.into() }, vec![]));
 
 		mock::start_active_era(1);
 
@@ -1715,6 +1717,7 @@ fn switching_roles() {
 
 		// 2 decides to be a validator. Consequences:
 		assert_ok!(Staking::validate(Origin::signed(2), ValidatorPrefs::default()));
+		assert_ok!(Session::set_keys(Origin::signed(2), SessionKeys { other: 2.into() }, vec![]));
 		// new stakes:
 		// 10: 1000 self vote
 		// 20: 1000 self vote + 250 vote
@@ -1819,6 +1822,11 @@ fn bond_with_little_staked_value_bounded() {
 			// Stingy validator.
 			assert_ok!(Staking::bond(Origin::signed(1), 2, 1, RewardDestination::Controller));
 			assert_ok!(Staking::validate(Origin::signed(2), ValidatorPrefs::default()));
+			assert_ok!(Session::set_keys(
+				Origin::signed(2),
+				SessionKeys { other: 2.into() },
+				vec![]
+			));
 
 			// 1 era worth of reward. BUT, we set the timestamp after on_initialize, so outdated by
 			// one block.
@@ -2051,12 +2059,12 @@ fn reward_from_authorship_event_handler_works() {
 	ExtBuilder::default().build_and_execute(|| {
 		use pallet_authorship::EventHandler;
 
-		assert_eq!(<pallet_authorship::Pallet<Test>>::author(), 11);
+		assert_eq!(<pallet_authorship::Pallet<Test>>::author(), Some(11));
 
-		<Pallet<Test>>::note_author(11);
-		<Pallet<Test>>::note_uncle(21, 1);
+		Pallet::<Test>::note_author(11);
+		Pallet::<Test>::note_uncle(21, 1);
 		// Rewarding the same two times works.
-		<Pallet<Test>>::note_uncle(11, 1);
+		Pallet::<Test>::note_uncle(11, 1);
 
 		// Not mandatory but must be coherent with rewards
 		assert_eq_uvec!(Session::validators(), vec![11, 21]);
@@ -2079,9 +2087,9 @@ fn add_reward_points_fns_works() {
 		// Not mandatory but must be coherent with rewards
 		assert_eq_uvec!(Session::validators(), vec![21, 11]);
 
-		<Pallet<Test>>::reward_by_ids(vec![(21, 1), (11, 1), (11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(21, 1), (11, 1), (11, 1)]);
 
-		<Pallet<Test>>::reward_by_ids(vec![(21, 1), (11, 1), (11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(21, 1), (11, 1), (11, 1)]);
 
 		assert_eq!(
 			ErasRewardPoints::<Test>::get(active_era()),
@@ -3091,13 +3099,13 @@ fn claim_reward_at_the_last_era_and_no_double_claim_and_invalid_claim() {
 		Payee::<Test>::insert(11, RewardDestination::Controller);
 		Payee::<Test>::insert(101, RewardDestination::Controller);
 
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 		// Compute total payout now for whole duration as other parameter won't change
 		let total_payout_0 = current_total_payout_for_duration(reward_time_per_era());
 
 		mock::start_active_era(1);
 
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 		// Change total issuance in order to modify total payout
 		let _ = Balances::deposit_creating(&999, 1_000_000_000);
 		// Compute total payout now for whole duration as other parameter won't change
@@ -3106,7 +3114,7 @@ fn claim_reward_at_the_last_era_and_no_double_claim_and_invalid_claim() {
 
 		mock::start_active_era(2);
 
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 		// Change total issuance in order to modify total payout
 		let _ = Balances::deposit_creating(&999, 1_000_000_000);
 		// Compute total payout now for whole duration as other parameter won't change
@@ -3266,7 +3274,7 @@ fn test_max_nominator_rewarded_per_validator_and_cant_steal_someone_else_reward(
 		}
 		mock::start_active_era(1);
 
-		<Pallet<Test>>::reward_by_ids(vec![(11, 1)]);
+		Pallet::<Test>::reward_by_ids(vec![(11, 1)]);
 		// compute and ensure the reward amount is greater than zero.
 		let _ = current_total_payout_for_duration(reward_time_per_era());
 

substrate/frame/sudo/src/lib.rs

@@ -146,7 +146,7 @@ pub mod pallet {
 		) -> DispatchResultWithPostInfo {
 			// This is a public call, so we ensure that the origin is some signed account.
 			let sender = ensure_signed(origin)?;
-			ensure!(sender == Self::key(), Error::<T>::RequireSudo);
+			ensure!(Self::key().map_or(false, |k| sender == k), Error::<T>::RequireSudo);
 
 			let res = call.dispatch_bypass_filter(frame_system::RawOrigin::Root.into());
 			Self::deposit_event(Event::Sudid { sudo_result: res.map(|_| ()).map_err(|e| e.error) });
@@ -172,7 +172,7 @@ pub mod pallet {
 		) -> DispatchResultWithPostInfo {
 			// This is a public call, so we ensure that the origin is some signed account.
 			let sender = ensure_signed(origin)?;
-			ensure!(sender == Self::key(), Error::<T>::RequireSudo);
+			ensure!(Self::key().map_or(false, |k| sender == k), Error::<T>::RequireSudo);
 
 			let res = call.dispatch_bypass_filter(frame_system::RawOrigin::Root.into());
 			Self::deposit_event(Event::Sudid { sudo_result: res.map(|_| ()).map_err(|e| e.error) });
@@ -197,11 +197,11 @@ pub mod pallet {
 		) -> DispatchResultWithPostInfo {
 			// This is a public call, so we ensure that the origin is some signed account.
 			let sender = ensure_signed(origin)?;
-			ensure!(sender == Self::key(), Error::<T>::RequireSudo);
+			ensure!(Self::key().map_or(false, |k| sender == k), Error::<T>::RequireSudo);
 			let new = T::Lookup::lookup(new)?;
 
-			Self::deposit_event(Event::KeyChanged { new_sudoer: Self::key() });
-			<Key<T>>::put(new);
+			Self::deposit_event(Event::KeyChanged { old_sudoer: Key::<T>::get() });
+			Key::<T>::put(&new);
 			// Sudo user does not pay a fee.
 			Ok(Pays::No.into())
 		}
@@ -234,7 +234,7 @@ pub mod pallet {
 		) -> DispatchResultWithPostInfo {
 			// This is a public call, so we ensure that the origin is some signed account.
 			let sender = ensure_signed(origin)?;
-			ensure!(sender == Self::key(), Error::<T>::RequireSudo);
+			ensure!(Self::key().map_or(false, |k| sender == k), Error::<T>::RequireSudo);
 
 			let who = T::Lookup::lookup(who)?;
 
@@ -253,8 +253,8 @@ pub mod pallet {
 	pub enum Event<T: Config> {
 		/// A sudo just took place. \[result\]
 		Sudid { sudo_result: DispatchResult },
-		/// The \[sudoer\] just switched identity; the old key is supplied.
-		KeyChanged { new_sudoer: T::AccountId },
+		/// The \[sudoer\] just switched identity; the old key is supplied if one existed.
+		KeyChanged { old_sudoer: Option<T::AccountId> },
 		/// A sudo just took place. \[result\]
 		SudoAsDone { sudo_result: DispatchResult },
 	}
@@ -269,25 +269,27 @@ pub mod pallet {
 	/// The `AccountId` of the sudo key.
 	#[pallet::storage]
 	#[pallet::getter(fn key)]
-	pub(super) type Key<T: Config> = StorageValue<_, T::AccountId, ValueQuery>;
+	pub(super) type Key<T: Config> = StorageValue<_, T::AccountId, OptionQuery>;
 
 	#[pallet::genesis_config]
 	pub struct GenesisConfig<T: Config> {
 		/// The `AccountId` of the sudo key.
-		pub key: T::AccountId,
+		pub key: Option<T::AccountId>,
 	}
 
 	#[cfg(feature = "std")]
 	impl<T: Config> Default for GenesisConfig<T> {
 		fn default() -> Self {
-			Self { key: Default::default() }
+			Self { key: None }
 		}
 	}
 
 	#[pallet::genesis_build]
 	impl<T: Config> GenesisBuild<T> for GenesisConfig<T> {
 		fn build(&self) {
-			<Key<T>>::put(&self.key);
+			if let Some(ref key) = self.key {
+				Key::<T>::put(key);
+			}
 		}
 	}
 }

substrate/frame/sudo/src/mock.rs

@@ -165,7 +165,7 @@ pub type LoggerCall = logger::Call<Test>;
 // Build test environment by setting the root `key` for the Genesis.
 pub fn new_test_ext(root_key: u64) -> sp_io::TestExternalities {
 	let mut t = frame_system::GenesisConfig::default().build_storage::<Test>().unwrap();
-	sudo::GenesisConfig::<Test> { key: root_key }
+	sudo::GenesisConfig::<Test> { key: Some(root_key) }
 		.assimilate_storage(&mut t)
 		.unwrap();
 	t.into()

substrate/frame/sudo/src/tests.rs

@@ -28,7 +28,7 @@ use mock::{
 fn test_setup_works() {
 	// Environment setup, logger storage, and sudo `key` retrieval should work as expected.
 	new_test_ext(1).execute_with(|| {
-		assert_eq!(Sudo::key(), 1u64);
+		assert_eq!(Sudo::key(), Some(1u64));
 		assert!(Logger::i32_log().is_empty());
 		assert!(Logger::account_log().is_empty());
 	});
@@ -105,7 +105,7 @@ fn set_key_basics() {
 	new_test_ext(1).execute_with(|| {
 		// A root `key` can change the root `key`
 		assert_ok!(Sudo::set_key(Origin::signed(1), 2));
-		assert_eq!(Sudo::key(), 2u64);
+		assert_eq!(Sudo::key(), Some(2u64));
 	});
 
 	new_test_ext(1).execute_with(|| {
@@ -123,10 +123,10 @@ fn set_key_emits_events_correctly() {
 
 		// A root `key` can change the root `key`.
 		assert_ok!(Sudo::set_key(Origin::signed(1), 2));
-		System::assert_has_event(TestEvent::Sudo(Event::KeyChanged { new_sudoer: 1 }));
+		System::assert_has_event(TestEvent::Sudo(Event::KeyChanged { old_sudoer: Some(1) }));
 		// Double check.
 		assert_ok!(Sudo::set_key(Origin::signed(2), 4));
-		System::assert_has_event(TestEvent::Sudo(Event::KeyChanged { new_sudoer: 2 }));
+		System::assert_has_event(TestEvent::Sudo(Event::KeyChanged { old_sudoer: Some(2) }));
 	});
 }
 

substrate/frame/support/src/traits/validation.rs

@@ -77,7 +77,7 @@ pub trait VerifySeal<Header, Author> {
 /// A session handler for specific key type.
 pub trait OneSessionHandler<ValidatorId>: BoundToRuntimeAppPublic {
 	/// The key type expected.
-	type Key: Decode + Default + RuntimeAppPublic;
+	type Key: Decode + RuntimeAppPublic;
 
 	/// The given validator set will be used for the genesis session.
 	/// It is guaranteed that the given validator set will also be used

substrate/frame/support/test/tests/construct_runtime.rs

@@ -229,6 +229,10 @@ pub type AccountId = <Signature as Verify>::Signer;
 pub type BlockNumber = u64;
 pub type Index = u64;
 
+fn test_pub() -> AccountId {
+	AccountId::from_raw([0; 32])
+}
+
 impl system::Config for Runtime {
 	type BaseCallFilter = frame_support::traits::Everything;
 	type Hash = H256;
@@ -451,13 +455,13 @@ fn event_codec() {
 	let event = system::Event::<Runtime>::ExtrinsicSuccess;
 	assert_eq!(Event::from(event).encode()[0], 30);
 
-	let event = module1::Event::<Runtime, module1::Instance1>::A(Default::default());
+	let event = module1::Event::<Runtime, module1::Instance1>::A(test_pub());
 	assert_eq!(Event::from(event).encode()[0], 31);
 
 	let event = module2::Event::A;
 	assert_eq!(Event::from(event).encode()[0], 32);
 
-	let event = module1::Event::<Runtime, module1::Instance2>::A(Default::default());
+	let event = module1::Event::<Runtime, module1::Instance2>::A(test_pub());
 	assert_eq!(Event::from(event).encode()[0], 33);
 
 	let event = nested::module3::Event::A;
@@ -466,19 +470,19 @@ fn event_codec() {
 	let event = module3::Event::A;
 	assert_eq!(Event::from(event).encode()[0], 35);
 
-	let event = module1::Event::<Runtime, module1::Instance5>::A(Default::default());
+	let event = module1::Event::<Runtime, module1::Instance5>::A(test_pub());
 	assert_eq!(Event::from(event).encode()[0], 4);
 
-	let event = module1::Event::<Runtime, module1::Instance6>::A(Default::default());
+	let event = module1::Event::<Runtime, module1::Instance6>::A(test_pub());
 	assert_eq!(Event::from(event).encode()[0], 1);
 
-	let event = module1::Event::<Runtime, module1::Instance7>::A(Default::default());
+	let event = module1::Event::<Runtime, module1::Instance7>::A(test_pub());
 	assert_eq!(Event::from(event).encode()[0], 2);
 
-	let event = module1::Event::<Runtime, module1::Instance8>::A(Default::default());
+	let event = module1::Event::<Runtime, module1::Instance8>::A(test_pub());
 	assert_eq!(Event::from(event).encode()[0], 12);
 
-	let event = module1::Event::<Runtime, module1::Instance9>::A(Default::default());
+	let event = module1::Event::<Runtime, module1::Instance9>::A(test_pub());
 	assert_eq!(Event::from(event).encode()[0], 13);
 }
 

substrate/frame/system/src/extensions/check_genesis.rs

@@ -19,7 +19,7 @@ use crate::{Config, Pallet};
 use codec::{Decode, Encode};
 use scale_info::TypeInfo;
 use sp_runtime::{
-	traits::{SignedExtension, Zero},
+	traits::{DispatchInfoOf, SignedExtension, Zero},
 	transaction_validity::TransactionValidityError,
 };
 
@@ -62,4 +62,14 @@ impl<T: Config + Send + Sync> SignedExtension for CheckGenesis<T> {
 	fn additional_signed(&self) -> Result<Self::AdditionalSigned, TransactionValidityError> {
 		Ok(<Pallet<T>>::block_hash(T::BlockNumber::zero()))
 	}
+
+	fn pre_dispatch(
+		self,
+		who: &Self::AccountId,
+		call: &Self::Call,
+		info: &DispatchInfoOf<Self::Call>,
+		len: usize,
+	) -> Result<Self::Pre, TransactionValidityError> {
+		Ok(self.validate(who, call, info, len).map(|_| ())?)
+	}
 }

substrate/frame/system/src/extensions/check_mortality.rs

@@ -85,6 +85,16 @@ impl<T: Config + Send + Sync> SignedExtension for CheckMortality<T> {
 			Ok(<Pallet<T>>::block_hash(n))
 		}
 	}
+
+	fn pre_dispatch(
+		self,
+		who: &Self::AccountId,
+		call: &Self::Call,
+		info: &DispatchInfoOf<Self::Call>,
+		len: usize,
+	) -> Result<Self::Pre, TransactionValidityError> {
+		Ok(self.validate(who, call, info, len).map(|_| ())?)
+	}
 }
 
 #[cfg(test)]

substrate/frame/system/src/extensions/check_non_zero_sender.rs

@@ -65,6 +65,16 @@ where
 		Ok(())
 	}
 
+	fn pre_dispatch(
+		self,
+		who: &Self::AccountId,
+		call: &Self::Call,
+		info: &DispatchInfoOf<Self::Call>,
+		len: usize,
+	) -> Result<Self::Pre, TransactionValidityError> {
+		Ok(self.validate(who, call, info, len).map(|_| ())?)
+	}
+
 	fn validate(
 		&self,
 		who: &Self::AccountId,

substrate/frame/system/src/extensions/check_spec_version.rs

@@ -18,7 +18,10 @@
 use crate::{Config, Pallet};
 use codec::{Decode, Encode};
 use scale_info::TypeInfo;
-use sp_runtime::{traits::SignedExtension, transaction_validity::TransactionValidityError};
+use sp_runtime::{
+	traits::{DispatchInfoOf, SignedExtension},
+	transaction_validity::TransactionValidityError,
+};
 
 /// Ensure the runtime version registered in the transaction is the same as at present.
 ///
@@ -59,4 +62,14 @@ impl<T: Config + Send + Sync> SignedExtension for CheckSpecVersion<T> {
 	fn additional_signed(&self) -> Result<Self::AdditionalSigned, TransactionValidityError> {
 		Ok(<Pallet<T>>::runtime_version().spec_version)
 	}
+
+	fn pre_dispatch(
+		self,
+		who: &Self::AccountId,
+		call: &Self::Call,
+		info: &DispatchInfoOf<Self::Call>,
+		len: usize,
+	) -> Result<Self::Pre, TransactionValidityError> {
+		Ok(self.validate(who, call, info, len).map(|_| ())?)
+	}
 }

substrate/frame/system/src/extensions/check_tx_version.rs

@@ -18,7 +18,10 @@
 use crate::{Config, Pallet};
 use codec::{Decode, Encode};
 use scale_info::TypeInfo;
-use sp_runtime::{traits::SignedExtension, transaction_validity::TransactionValidityError};
+use sp_runtime::{
+	traits::{DispatchInfoOf, SignedExtension},
+	transaction_validity::TransactionValidityError,
+};
 
 /// Ensure the transaction version registered in the transaction is the same as at present.
 ///
@@ -59,4 +62,13 @@ impl<T: Config + Send + Sync> SignedExtension for CheckTxVersion<T> {
 	fn additional_signed(&self) -> Result<Self::AdditionalSigned, TransactionValidityError> {
 		Ok(<Pallet<T>>::runtime_version().transaction_version)
 	}
+	fn pre_dispatch(
+		self,
+		who: &Self::AccountId,
+		call: &Self::Call,
+		info: &DispatchInfoOf<Self::Call>,
+		len: usize,
+	) -> Result<Self::Pre, TransactionValidityError> {
+		Ok(self.validate(who, call, info, len).map(|_| ())?)
+	}
 }

substrate/frame/system/src/extensions/check_weight.rs

@@ -223,7 +223,7 @@ where
 	}
 
 	fn post_dispatch(
-		_pre: Self::Pre,
+		_pre: Option<Self::Pre>,
 		info: &DispatchInfoOf<Self::Call>,
 		post_info: &PostDispatchInfoOf<Self::Call>,
 		_len: usize,
@@ -563,7 +563,13 @@ mod tests {
 			let pre = CheckWeight::<Test>(PhantomData).pre_dispatch(&1, CALL, &info, len).unwrap();
 			assert_eq!(BlockWeight::<Test>::get().total(), info.weight + 256);
 
-			assert_ok!(CheckWeight::<Test>::post_dispatch(pre, &info, &post_info, len, &Ok(())));
+			assert_ok!(CheckWeight::<Test>::post_dispatch(
+				Some(pre),
+				&info,
+				&post_info,
+				len,
+				&Ok(())
+			));
 			assert_eq!(BlockWeight::<Test>::get().total(), post_info.actual_weight.unwrap() + 256);
 		})
 	}
@@ -587,7 +593,13 @@ mod tests {
 				info.weight + 128 + block_weights().get(DispatchClass::Normal).base_extrinsic,
 			);
 
-			assert_ok!(CheckWeight::<Test>::post_dispatch(pre, &info, &post_info, len, &Ok(())));
+			assert_ok!(CheckWeight::<Test>::post_dispatch(
+				Some(pre),
+				&info,
+				&post_info,
+				len,
+				&Ok(())
+			));
 			assert_eq!(
 				BlockWeight::<Test>::get().total(),
 				info.weight + 128 + block_weights().get(DispatchClass::Normal).base_extrinsic,

substrate/frame/system/src/lib.rs

@@ -238,7 +238,6 @@ pub mod pallet {
 			+ Debug
 			+ MaybeDisplay
 			+ Ord
-			+ Default
 			+ MaxEncodedLen;
 
 		/// Converting trait to take a source type and convert to `AccountId`.

substrate/frame/tips/src/lib.rs

@@ -61,7 +61,7 @@ pub mod migrations;
 pub mod weights;
 
 use sp_runtime::{
-	traits::{AccountIdConversion, BadOrigin, Hash, Zero},
+	traits::{AccountIdConversion, BadOrigin, Hash, TrailingZeroInput, Zero},
 	Percent, RuntimeDebug,
 };
 use sp_std::prelude::*;
@@ -580,6 +580,9 @@ impl<T: Config> Pallet<T> {
 
 		use frame_support::{migration::storage_key_iter, Twox64Concat};
 
+		let zero_account = T::AccountId::decode(&mut TrailingZeroInput::new(&[][..]))
+			.expect("infinite input; qed");
+
 		for (hash, old_tip) in storage_key_iter::<
 			T::Hash,
 			OldOpenTip<T::AccountId, BalanceOf<T>, T::BlockNumber, T::Hash>,
@@ -589,7 +592,7 @@ impl<T: Config> Pallet<T> {
 		{
 			let (finder, deposit, finders_fee) = match old_tip.finder {
 				Some((finder, deposit)) => (finder, deposit, true),
-				None => (T::AccountId::default(), Zero::zero(), false),
+				None => (zero_account.clone(), Zero::zero(), false),
 			};
 			let new_tip = OpenTip {
 				reason: old_tip.reason,

substrate/frame/transaction-payment/asset-tx-payment/src/lib.rs

@@ -244,43 +244,44 @@ where
 	}
 
 	fn post_dispatch(
-		pre: Self::Pre,
+		pre: Option<Self::Pre>,
 		info: &DispatchInfoOf<Self::Call>,
 		post_info: &PostDispatchInfoOf<Self::Call>,
 		len: usize,
 		result: &DispatchResult,
 	) -> Result<(), TransactionValidityError> {
-		let (tip, who, initial_payment) = pre;
-		match initial_payment {
-			InitialPayment::Native(already_withdrawn) => {
-				pallet_transaction_payment::ChargeTransactionPayment::<T>::post_dispatch(
-					(tip, who, already_withdrawn),
-					info,
-					post_info,
-					len,
-					result,
-				)?;
-			},
-			InitialPayment::Asset(already_withdrawn) => {
-				let actual_fee = pallet_transaction_payment::Pallet::<T>::compute_actual_fee(
-					len as u32, info, post_info, tip,
-				);
-				T::OnChargeAssetTransaction::correct_and_deposit_fee(
-					&who,
-					info,
-					post_info,
-					actual_fee.into(),
-					tip.into(),
-					already_withdrawn.into(),
-				)?;
-			},
-			InitialPayment::Nothing => {
-				// `actual_fee` should be zero here for any signed extrinsic. It would be non-zero
-				// here in case of unsigned extrinsics as they don't pay fees but
-				// `compute_actual_fee` is not aware of them. In both cases it's fine to just move
-				// ahead without adjusting the fee, though, so we do nothing.
-				debug_assert!(tip.is_zero(), "tip should be zero if initial fee was zero.");
-			},
+		if let Some((tip, who, initial_payment)) = pre {
+			match initial_payment {
+				InitialPayment::Native(already_withdrawn) => {
+					pallet_transaction_payment::ChargeTransactionPayment::<T>::post_dispatch(
+						Some((tip, who, already_withdrawn)),
+						info,
+						post_info,
+						len,
+						result,
+					)?;
+				},
+				InitialPayment::Asset(already_withdrawn) => {
+					let actual_fee = pallet_transaction_payment::Pallet::<T>::compute_actual_fee(
+						len as u32, info, post_info, tip,
+					);
+					T::OnChargeAssetTransaction::correct_and_deposit_fee(
+						&who,
+						info,
+						post_info,
+						actual_fee.into(),
+						tip.into(),
+						already_withdrawn.into(),
+					)?;
+				},
+				InitialPayment::Nothing => {
+					// `actual_fee` should be zero here for any signed extrinsic. It would be
+					// non-zero here in case of unsigned extrinsics as they don't pay fees but
+					// `compute_actual_fee` is not aware of them. In both cases it's fine to just
+					// move ahead without adjusting the fee, though, so we do nothing.
+					debug_assert!(tip.is_zero(), "tip should be zero if initial fee was zero.");
+				},
+			}
 		}
 
 		Ok(())

substrate/frame/transaction-payment/asset-tx-payment/src/tests.rs

@@ -201,10 +201,11 @@ impl pallet_authorship::Config for Runtime {
 pub struct CreditToBlockAuthor;
 impl HandleCredit<AccountId, Assets> for CreditToBlockAuthor {
 	fn handle_credit(credit: CreditOf<AccountId, Assets>) {
-		let author = pallet_authorship::Pallet::<Runtime>::author();
-		// What to do in case paying the author fails (e.g. because `fee < min_balance`)
-		// default: drop the result which will trigger the `OnDrop` of the imbalance.
-		let _ = <Assets as Balanced<AccountId>>::resolve(&author, credit);
+		if let Some(author) = pallet_authorship::Pallet::<Runtime>::author() {
+			// What to do in case paying the author fails (e.g. because `fee < min_balance`)
+			// default: drop the result which will trigger the `OnDrop` of the imbalance.
+			let _ = <Assets as Balanced<AccountId>>::resolve(&author, credit);
+		}
 	}
 }
 
@@ -304,7 +305,7 @@ fn transaction_payment_in_native_possible() {
 			assert_eq!(Balances::free_balance(1), initial_balance - 5 - 5 - 10);
 
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				Some(pre),
 				&info_from_weight(5),
 				&default_post_info(),
 				len,
@@ -319,7 +320,7 @@ fn transaction_payment_in_native_possible() {
 			assert_eq!(Balances::free_balance(2), initial_balance_for_2 - 5 - 10 - 100 - 5);
 
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				Some(pre),
 				&info_from_weight(100),
 				&post_info_from_weight(50),
 				len,
@@ -370,7 +371,7 @@ fn transaction_payment_in_asset_possible() {
 			assert_eq!(Assets::balance(asset_id, BLOCK_AUTHOR), 0);
 
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				Some(pre),
 				&info_from_weight(weight),
 				&default_post_info(),
 				len,
@@ -423,7 +424,7 @@ fn transaction_payment_without_fee() {
 			assert_eq!(Assets::balance(asset_id, BLOCK_AUTHOR), 0);
 
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				Some(pre),
 				&info_from_weight(weight),
 				&post_info_from_pays(Pays::No),
 				len,
@@ -475,7 +476,7 @@ fn asset_transaction_payment_with_tip_and_refund() {
 
 			let final_weight = 50;
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				Some(pre),
 				&info_from_weight(weight),
 				&post_info_from_weight(final_weight),
 				len,
@@ -528,7 +529,7 @@ fn payment_from_account_with_only_assets() {
 			assert_eq!(Assets::balance(asset_id, caller), balance - fee);
 
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				Some(pre),
 				&info_from_weight(weight),
 				&default_post_info(),
 				len,
@@ -612,7 +613,7 @@ fn converted_fee_is_never_zero_if_input_fee_is_not() {
 				assert_eq!(Assets::balance(asset_id, caller), balance);
 
 				assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&info_from_pays(Pays::No),
 					&post_info_from_pays(Pays::No),
 					len,
@@ -627,7 +628,7 @@ fn converted_fee_is_never_zero_if_input_fee_is_not() {
 			assert_eq!(Assets::balance(asset_id, caller), balance - 1);
 
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				Some(pre),
 				&info_from_weight(weight),
 				&default_post_info(),
 				len,
@@ -684,7 +685,7 @@ fn post_dispatch_fee_is_zero_if_pre_dispatch_fee_is_zero() {
 			// `Pays::Yes` on post-dispatch does not mean we pay (we never charge more than the
 			// initial fee)
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				Some(pre),
 				&info_from_pays(Pays::No),
 				&post_info_from_pays(Pays::Yes),
 				len,
@@ -721,7 +722,7 @@ fn post_dispatch_fee_is_zero_if_unsigned_pre_dispatch_fee_is_zero() {
 			assert_eq!(Assets::balance(asset_id, caller), balance);
 			let weight = 1;
 			let len = 1;
-			let pre = ChargeAssetTxPayment::<Runtime>::pre_dispatch_unsigned(
+			ChargeAssetTxPayment::<Runtime>::pre_dispatch_unsigned(
 				CALL,
 				&info_from_weight(weight),
 				len,
@@ -729,17 +730,11 @@ fn post_dispatch_fee_is_zero_if_unsigned_pre_dispatch_fee_is_zero() {
 			.unwrap();
 
 			assert_eq!(Assets::balance(asset_id, caller), balance);
-			let (_tip, _who, initial_payment) = &pre;
-			let not_paying = match initial_payment {
-				&InitialPayment::Nothing => true,
-				_ => false,
-			};
-			assert!(not_paying, "initial payment is Nothing for unsigned extrinsics");
 
 			// `Pays::Yes` on post-dispatch does not mean we pay (we never charge more than the
 			// initial fee)
 			assert_ok!(ChargeAssetTxPayment::<Runtime>::post_dispatch(
-				pre,
+				None,
 				&info_from_weight(weight),
 				&post_info_from_pays(Pays::Yes),
 				len,

substrate/frame/transaction-payment/src/lib.rs

@@ -704,7 +704,7 @@ where
 	type Pre = (
 		// tip
 		BalanceOf<T>,
-		// who paid the fee
+		// who paid the fee - this is an option to allow for a Default impl.
 		Self::AccountId,
 		// imbalance resulting from withdrawing the fee
 		<<T as Config>::OnChargeTransaction as OnChargeTransaction<T>>::LiquidityInfo,
@@ -740,17 +740,18 @@ where
 	}
 
 	fn post_dispatch(
-		pre: Self::Pre,
+		maybe_pre: Option<Self::Pre>,
 		info: &DispatchInfoOf<Self::Call>,
 		post_info: &PostDispatchInfoOf<Self::Call>,
 		len: usize,
 		_result: &DispatchResult,
 	) -> Result<(), TransactionValidityError> {
-		let (tip, who, imbalance) = pre;
-		let actual_fee = Pallet::<T>::compute_actual_fee(len as u32, info, post_info, tip);
-		T::OnChargeTransaction::correct_and_deposit_fee(
-			&who, info, post_info, actual_fee, tip, imbalance,
-		)?;
+		if let Some((tip, who, imbalance)) = maybe_pre {
+			let actual_fee = Pallet::<T>::compute_actual_fee(len as u32, info, post_info, tip);
+			T::OnChargeTransaction::correct_and_deposit_fee(
+				&who, info, post_info, actual_fee, tip, imbalance,
+			)?;
+		}
 		Ok(())
 	}
 }
@@ -1014,7 +1015,7 @@ mod tests {
 				assert_eq!(Balances::free_balance(1), 100 - 5 - 5 - 10);
 
 				assert_ok!(ChargeTransactionPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&info_from_weight(5),
 					&default_post_info(),
 					len,
@@ -1032,7 +1033,7 @@ mod tests {
 				assert_eq!(Balances::free_balance(2), 200 - 5 - 10 - 100 - 5);
 
 				assert_ok!(ChargeTransactionPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&info_from_weight(100),
 					&post_info_from_weight(50),
 					len,
@@ -1061,7 +1062,7 @@ mod tests {
 				assert_eq!(Balances::free_balance(2), 200 - 5 - 10 - 150 - 5);
 
 				assert_ok!(ChargeTransactionPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&info_from_weight(100),
 					&post_info_from_weight(50),
 					len,
@@ -1356,7 +1357,7 @@ mod tests {
 				assert_eq!(Balances::free_balance(2), 0);
 
 				assert_ok!(ChargeTransactionPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&info_from_weight(100),
 					&post_info_from_weight(50),
 					len,
@@ -1390,7 +1391,7 @@ mod tests {
 				assert_eq!(Balances::free_balance(2), 200 - 5 - 10 - 100 - 5);
 
 				assert_ok!(ChargeTransactionPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&info_from_weight(100),
 					&post_info_from_weight(101),
 					len,
@@ -1418,7 +1419,7 @@ mod tests {
 					.unwrap();
 				assert_eq!(Balances::total_balance(&user), 0);
 				assert_ok!(ChargeTransactionPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&dispatch_info,
 					&default_post_info(),
 					len,
@@ -1450,7 +1451,7 @@ mod tests {
 					.unwrap();
 
 				ChargeTransactionPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&info,
 					&post_info,
 					len,
@@ -1601,7 +1602,7 @@ mod tests {
 					.unwrap();
 
 				ChargeTransactionPayment::<Runtime>::post_dispatch(
-					pre,
+					Some(pre),
 					&info,
 					&post_info,
 					len,

substrate/frame/utility/src/lib.rs

@@ -65,7 +65,7 @@ use frame_support::{
 };
 use sp_core::TypeId;
 use sp_io::hashing::blake2_256;
-use sp_runtime::traits::Dispatchable;
+use sp_runtime::traits::{Dispatchable, TrailingZeroInput};
 use sp_std::prelude::*;
 pub use weights::WeightInfo;
 
@@ -400,6 +400,7 @@ impl<T: Config> Pallet<T> {
 	/// Derive a derivative account ID from the owner account and the sub-account index.
 	pub fn derivative_account_id(who: T::AccountId, index: u16) -> T::AccountId {
 		let entropy = (b"modlpy/utilisuba", who, index).using_encoded(blake2_256);
-		T::AccountId::decode(&mut &entropy[..]).unwrap_or_default()
+		Decode::decode(&mut TrailingZeroInput::new(entropy.as_ref()))
+			.expect("infinite length input; no invalid inputs for type; qed")
 	}
 }