Deprecate scheduler traits v1 and v2 (#3718)

This PR add `#[deprecated]` attribute to v1 and v2 of the schedule
trait. Proposed in this issue:
#3676

```rust
#[allow(deprecated)]
#[deprecated = "traits::schedule::v1 is deprecated. Please use v3 instead."]
pub mod v1 {
...
}

#[allow(deprecated)]
#[deprecated = "traits::schedule::v2 is deprecated. Please use v3 instead."]
pub mod v2 {
...
}
```

polkadot address: 19nSqFQorfF2HxD3oBzWM3oCh4SaCRKWt1yvmgaPYGCo71J

---------

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>

prdoc/pr_3718.prdoc

@@ -0,0 +1,13 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Deprecate scheduler traits v1 and v2
+
+doc:
+  - audience: Runtime Dev
+    description: |
+        Add `#[deprecated]` attribute to scheduler traits v1 and v2 to deprecate old versions
+
+crates:
+    - name: frame-support
+    - name: pallet-scheduler

substrate/frame/scheduler/src/lib.rs

@@ -1446,6 +1446,7 @@ impl<T: Config> Pallet<T> {
 	}
 }
 
+#[allow(deprecated)]
 impl<T: Config> schedule::v2::Anon<BlockNumberFor<T>, <T as Config>::RuntimeCall, T::PalletsOrigin>
 	for Pallet<T>
 {
@@ -1480,6 +1481,8 @@ impl<T: Config> schedule::v2::Anon<BlockNumberFor<T>, <T as Config>::RuntimeCall
 	}
 }
 
+// TODO: migrate `schedule::v2::Anon` to `v3`
+#[allow(deprecated)]
 impl<T: Config> schedule::v2::Named<BlockNumberFor<T>, <T as Config>::RuntimeCall, T::PalletsOrigin>
 	for Pallet<T>
 {

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

@@ -130,7 +130,7 @@ impl<T: Decode, H> MaybeHashed<T, H> {
 	}
 }
 
-// TODO: deprecate
+#[deprecated(note = "Use `v3` instead. Will be removed after September 2024.")]
 pub mod v1 {
 	use super::*;
 
@@ -218,10 +218,12 @@ pub mod v1 {
 		fn next_dispatch_time(id: Vec<u8>) -> Result<BlockNumber, ()>;
 	}
 
+	#[allow(deprecated)]
 	impl<T, BlockNumber, Call, RuntimeOrigin> Anon<BlockNumber, Call, RuntimeOrigin> for T
 	where
 		T: v2::Anon<BlockNumber, Call, RuntimeOrigin>,
 	{
+		#[allow(deprecated)]
 		type Address = T::Address;
 
 		fn schedule(
@@ -232,29 +234,36 @@ pub mod v1 {
 			call: Call,
 		) -> Result<Self::Address, DispatchError> {
 			let c = MaybeHashed::<Call, T::Hash>::Value(call);
+
+			#[allow(deprecated)]
 			T::schedule(when, maybe_periodic, priority, origin, c)
 		}
 
 		fn cancel(address: Self::Address) -> Result<(), ()> {
+			#[allow(deprecated)]
 			T::cancel(address)
 		}
 
 		fn reschedule(
 			address: Self::Address,
 			when: DispatchTime<BlockNumber>,
 		) -> Result<Self::Address, DispatchError> {
+			#[allow(deprecated)]
 			T::reschedule(address, when)
 		}
 
 		fn next_dispatch_time(address: Self::Address) -> Result<BlockNumber, ()> {
+			#[allow(deprecated)]
 			T::next_dispatch_time(address)
 		}
 	}
 
+	#[allow(deprecated)]
 	impl<T, BlockNumber, Call, RuntimeOrigin> Named<BlockNumber, Call, RuntimeOrigin> for T
 	where
 		T: v2::Named<BlockNumber, Call, RuntimeOrigin>,
 	{
+		#[allow(deprecated)]
 		type Address = T::Address;
 
 		fn schedule_named(
@@ -266,27 +275,31 @@ pub mod v1 {
 			call: Call,
 		) -> Result<Self::Address, ()> {
 			let c = MaybeHashed::<Call, T::Hash>::Value(call);
+			#[allow(deprecated)]
 			T::schedule_named(id, when, maybe_periodic, priority, origin, c)
 		}
 
 		fn cancel_named(id: Vec<u8>) -> Result<(), ()> {
+			#[allow(deprecated)]
 			T::cancel_named(id)
 		}
 
 		fn reschedule_named(
 			id: Vec<u8>,
 			when: DispatchTime<BlockNumber>,
 		) -> Result<Self::Address, DispatchError> {
+			#[allow(deprecated)]
 			T::reschedule_named(id, when)
 		}
 
 		fn next_dispatch_time(id: Vec<u8>) -> Result<BlockNumber, ()> {
+			#[allow(deprecated)]
 			T::next_dispatch_time(id)
 		}
 	}
 }
 
-// TODO: deprecate
+#[deprecated(note = "Use `v3` instead. Will be removed after September 2024.")]
 pub mod v2 {
 	use super::*;
 
@@ -478,4 +491,5 @@ pub mod v3 {
 	}
 }
 
+#[allow(deprecated)]
 pub use v1::*;