Add Authorize Upgrade Pattern to Frame System (#2682)

Adds the `authorize_upgrade` -> `enact_authorized_upgrade` pattern to
`frame-system`. This will be useful for upgrading bridged chains that
are under the governance of Polkadot without passing entire runtime Wasm
blobs over a bridge.

Notes:

- Changed `enact_authorized_upgrade` to `apply_authorized_upgrade`.
Personal opinion, "apply" more accurately expresses what it's doing. Can
change back if outvoted.
- Remove `check_version` in favor of two extrinsics, so as to make
_checked_ the default.
- Left calls in `parachain-system` and marked as deprecated to prevent
breaking the API. They just call into the `frame-system` functions.
- Updated `frame-system` benchmarks to v2 syntax.

---------

Co-authored-by: command-bot <>

substrate/frame/system/src/tests.rs

@@ -675,6 +675,46 @@ fn set_code_with_real_wasm_blob() {
 	});
 }
 
+#[test]
+fn set_code_via_authorization_works() {
+	let executor = substrate_test_runtime_client::new_native_or_wasm_executor();
+	let mut ext = new_test_ext();
+	ext.register_extension(sp_core::traits::ReadRuntimeVersionExt::new(executor));
+	ext.execute_with(|| {
+		System::set_block_number(1);
+		assert!(System::authorized_upgrade().is_none());
+
+		let runtime = substrate_test_runtime_client::runtime::wasm_binary_unwrap().to_vec();
+		let hash = <mock::Test as pallet::Config>::Hashing::hash(&runtime);
+
+		// Can't apply before authorization
+		assert_noop!(
+			System::apply_authorized_upgrade(RawOrigin::None.into(), runtime.clone()),
+			Error::<Test>::NothingAuthorized,
+		);
+
+		// Can authorize
+		assert_ok!(System::authorize_upgrade(RawOrigin::Root.into(), hash));
+		System::assert_has_event(
+			SysEvent::UpgradeAuthorized { code_hash: hash, check_version: true }.into(),
+		);
+		assert!(System::authorized_upgrade().is_some());
+
+		// Can't be sneaky
+		let mut bad_runtime = substrate_test_runtime_client::runtime::wasm_binary_unwrap().to_vec();
+		bad_runtime.extend(b"sneaky");
+		assert_noop!(
+			System::apply_authorized_upgrade(RawOrigin::None.into(), bad_runtime),
+			Error::<Test>::Unauthorized,
+		);
+
+		// Can apply correct runtime
+		assert_ok!(System::apply_authorized_upgrade(RawOrigin::None.into(), runtime));
+		System::assert_has_event(SysEvent::CodeUpdated.into());
+		assert!(System::authorized_upgrade().is_none());
+	});
+}
+
 #[test]
 fn runtime_upgraded_with_set_storage() {
 	let executor = substrate_test_runtime_client::new_native_or_wasm_executor();