contracts: Release as v3.0.0 and add reserved field to ContractInfoOf (#8175)

* contracts: Update README

* contracts: Add CHANGELOG.md

* contracts: Bump version to v3.0.0 and allow publish

* Typos

Co-authored-by: Andrew Jones <ascjones@gmail.com>

* Improve wording in the changelog

* contracts: Add reserved field to ContractInfoOf for future proofing

* also bump frame-benchmarking

* update lockfile

Co-authored-by: Andrew Jones <ascjones@gmail.com>
Co-authored-by: Benjamin Kampmann <ben@parity.io>

substrate/frame/contracts/src/lib.rs

@@ -837,6 +837,8 @@ pub struct RawAliveContractInfo<CodeHash, Balance, BlockNumber> {
 	pub deduct_block: BlockNumber,
 	/// Last block child storage has been written.
 	pub last_write: Option<BlockNumber>,
+	/// This field is reserved for future evolution of format.
+	pub _reserved: Option<()>,
 }
 
 impl<CodeHash, Balance, BlockNumber> RawAliveContractInfo<CodeHash, Balance, BlockNumber> {

substrate/frame/contracts/src/rent.rs

@@ -514,14 +514,12 @@ where
 		<ContractInfoOf<T>>::remove(&origin);
 		let tombstone_code_len = E::remove_user(origin_contract.code_hash);
 		<ContractInfoOf<T>>::insert(&dest, ContractInfo::Alive(AliveContractInfo::<T> {
-			trie_id: origin_contract.trie_id,
-			storage_size: origin_contract.storage_size,
-			pair_count: origin_contract.pair_count,
 			code_hash,
 			rent_allowance,
 			rent_payed: <BalanceOf<T>>::zero(),
 			deduct_block: current_block,
 			last_write,
+			.. origin_contract
 		}));
 
 		let origin_free_balance = T::Currency::free_balance(&origin);

substrate/frame/contracts/src/storage.rs

@@ -182,6 +182,7 @@ where
 				rent_payed: <BalanceOf<T>>::zero(),
 				pair_count: 0,
 				last_write: None,
+				_reserved: None,
 			};
 
 			*existing = Some(contract.into());

substrate/frame/contracts/src/tests.rs

@@ -392,6 +392,7 @@ fn account_removal_does_not_remove_storage() {
 				rent_allowance: 40,
 				rent_payed: 0,
 				last_write: None,
+				_reserved: None,
 			});
 			let _ = Balances::deposit_creating(&ALICE, 110);
 			ContractInfoOf::<Test>::insert(ALICE, &alice_contract_info);
@@ -407,6 +408,7 @@ fn account_removal_does_not_remove_storage() {
 				rent_allowance: 40,
 				rent_payed: 0,
 				last_write: None,
+				_reserved: None,
 			});
 			let _ = Balances::deposit_creating(&BOB, 110);
 			ContractInfoOf::<Test>::insert(BOB, &bob_contract_info);