Remove grandpa `StoredPendingChange` shim (#8788)

* Remove grandpa StoredPendingChange shim

* Unused import

substrate/frame/grandpa/src/lib.rs

@@ -107,21 +107,8 @@ pub trait WeightInfo {
 	fn note_stalled() -> Weight;
 }
 
-/// A stored pending change, old format.
-// TODO: remove shim
-// https://github.com/paritytech/substrate/issues/1614
-#[derive(Encode, Decode)]
-pub struct OldStoredPendingChange<N> {
-	/// The block number this was scheduled at.
-	pub scheduled_at: N,
-	/// The delay in blocks until it will be applied.
-	pub delay: N,
-	/// The next authority set.
-	pub next_authorities: AuthorityList,
-}
-
 /// A stored pending change.
-#[derive(Encode)]
+#[derive(Encode, Decode)]
 pub struct StoredPendingChange<N> {
 	/// The block number this was scheduled at.
 	pub scheduled_at: N,
@@ -134,20 +121,6 @@ pub struct StoredPendingChange<N> {
 	pub forced: Option<N>,
 }
 
-impl<N: Decode> Decode for StoredPendingChange<N> {
-	fn decode<I: codec::Input>(value: &mut I) -> core::result::Result<Self, codec::Error> {
-		let old = OldStoredPendingChange::decode(value)?;
-		let forced = <Option<N>>::decode(value).unwrap_or(None);
-
-		Ok(StoredPendingChange {
-			scheduled_at: old.scheduled_at,
-			delay: old.delay,
-			next_authorities: old.next_authorities,
-			forced,
-		})
-	}
-}
-
 /// Current state of the GRANDPA authority set. State transitions must happen in
 /// the same order of states defined below, e.g. `Paused` implies a prior
 /// `PendingPause`.

substrate/frame/grandpa/src/tests.rs

@@ -21,7 +21,7 @@
 
 use super::{Call, Event, *};
 use crate::mock::*;
-use codec::{Decode, Encode};
+use codec::Encode;
 use fg_primitives::ScheduledChange;
 use frame_support::{
 	assert_err, assert_ok, assert_noop,
@@ -127,22 +127,6 @@ fn cannot_schedule_change_when_one_pending() {
 	});
 }
 
-#[test]
-fn new_decodes_from_old() {
-	let old = OldStoredPendingChange {
-		scheduled_at: 5u32,
-		delay: 100u32,
-		next_authorities: to_authorities(vec![(1, 5), (2, 10), (3, 2)]),
-	};
-
-	let encoded = old.encode();
-	let new = StoredPendingChange::<u32>::decode(&mut &encoded[..]).unwrap();
-	assert!(new.forced.is_none());
-	assert_eq!(new.scheduled_at, old.scheduled_at);
-	assert_eq!(new.delay, old.delay);
-	assert_eq!(new.next_authorities, old.next_authorities);
-}
-
 #[test]
 fn dispatch_forced_change() {
 	new_test_ext(vec![(1, 1), (2, 1), (3, 1)]).execute_with(|| {