Simplify deposit_event declaration in decl_module (#3506)

* simplify module deposit_event declaration

* fix

* bump version

* fix

* fix test

* fix doc

substrate/node-template/runtime/src/template.rs

@@ -35,7 +35,7 @@ decl_module! {
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
 		// Initializing events
 		// this is needed only if you are using events in your module
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 
 		// Just a dummy entry point.
 		// function that can be called by the external world as an extrinsics call

substrate/node/runtime/src/lib.rs

@@ -80,7 +80,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	// implementation changes and behavior does not, then leave spec_version as
 	// is and increment impl_version.
 	spec_version: 154,
-	impl_version: 156,
+	impl_version: 157,
 	apis: RUNTIME_API_VERSIONS,
 };
 

substrate/srml/assets/src/lib.rs

@@ -149,7 +149,7 @@ pub trait Trait: system::Trait {
 
 decl_module! {
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 		/// Issue a new class of fungible assets. There are, and will only ever be, `total`
 		/// such assets and they'll all belong to the `origin` initially. It will have an
 		/// identifier `AssetId` instance: this will be specified in the `Issued` event.

substrate/srml/balances/src/lib.rs

@@ -413,7 +413,7 @@ decl_module! {
 		/// The fee to be paid for making a transaction; the per-byte portion.
 		const TransactionByteFee: T::Balance = T::TransactionByteFee::get();
 
-		fn deposit_event<T, I>() = default;
+		fn deposit_event() = default;
 
 		/// Transfer some liquid free balance to another account.
 		///

substrate/srml/collective/src/lib.rs

@@ -138,7 +138,7 @@ decl_event!(
 // operational class.
 decl_module! {
 	pub struct Module<T: Trait<I>, I: Instance=DefaultInstance> for enum Call where origin: <T as system::Trait>::Origin {
-		fn deposit_event<T, I>() = default;
+		fn deposit_event() = default;
 
 		/// Set the collective's membership manually to `new_members`. Be nice to the chain and
 		/// provide it pre-sorted.

substrate/srml/contracts/src/lib.rs

@@ -504,7 +504,7 @@ decl_module! {
 		/// default value is 10_000_000.
 		const BlockGasLimit: Gas = T::BlockGasLimit::get();
 
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 
 		/// Updates the schedule for metering contracts.
 		///

substrate/srml/democracy/src/lib.rs

@@ -354,7 +354,7 @@ decl_module! {
 		/// Period in blocks where an external proposal may not be re-submitted after being vetoed.
 		const CooloffPeriod: T::BlockNumber = T::CooloffPeriod::get();
 
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 
 		/// Propose a sensitive action to be taken.
 		///

substrate/srml/elections/src/lib.rs

@@ -296,7 +296,7 @@ decl_module! {
 		/// The chunk size of the approval vector.
 		const APPROVAL_SET_SIZE: u32 = APPROVAL_SET_SIZE as u32;
 
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 
 		/// Set candidate approvals. Approval slots stay valid as long as candidates in those slots
 		/// are registered.

substrate/srml/example/src/lib.rs

@@ -363,7 +363,7 @@ decl_module! {
 		/// It is also possible to provide a custom implementation.
 		/// For non-generic events, the generic parameter just needs to be dropped, so that it
 		/// looks like: `fn deposit_event() = default;`.
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 		/// This is your public interface. Be extremely careful.
 		/// This is just a simple example of how to interact with the module from the external
 		/// world.

substrate/srml/generic-asset/src/lib.rs

@@ -324,7 +324,7 @@ impl<AccountId> Into<PermissionVersions<AccountId>> for PermissionLatest<Account
 
 decl_module! {
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 
 		/// Create a new kind of asset.
 		fn create(origin, options: AssetOptions<T::Balance, T::AccountId>) -> Result {

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

@@ -238,7 +238,7 @@ decl_storage! {
 
 decl_module! {
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 
 		fn heartbeat(
 			origin,

substrate/srml/indices/src/lib.rs

@@ -73,7 +73,7 @@ pub trait Trait: system::Trait {
 
 decl_module! {
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 	}
 }
 

substrate/srml/membership/src/lib.rs

@@ -99,7 +99,7 @@ decl_module! {
 		for enum Call
 		where origin: T::Origin
 	{
-		fn deposit_event<T, I>() = default;
+		fn deposit_event() = default;
 
 		/// Add a member `who` to the set.
 		///

substrate/srml/scored-pool/src/lib.rs

@@ -228,7 +228,7 @@ decl_module! {
 		for enum Call
 		where origin: T::Origin
 	{
-		fn deposit_event<T, I>() = default;
+		fn deposit_event() = default;
 
 		/// Every `Period` blocks the `Members` set is refreshed from the
 		/// highest scoring members in the pool.

substrate/srml/staking/src/lib.rs

@@ -674,7 +674,7 @@ decl_module! {
 		/// Number of eras that staked funds must remain bonded for.
 		const BondingDuration: EraIndex = T::BondingDuration::get();
 
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 
 		fn on_finalize() {
 			// Set the start of the first era.
@@ -1595,7 +1595,7 @@ impl<T, Reporter, Offender, R, O> ReportOffence<Reporter, Offender, O>
 			R::report_offence(reporters, offence)
 		} else {
 			<Module<T>>::deposit_event(
-				RawEvent::OldSlashingReportDiscarded(offence_session).into()
+				RawEvent::OldSlashingReportDiscarded(offence_session)
 			)
 		}
 	}

substrate/srml/sudo/src/lib.rs

@@ -106,7 +106,7 @@ pub trait Trait: system::Trait {
 decl_module! {
 	// Simple declaration of the `Module` type. Lets the macro know what it's working on.
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 
 		/// Authenticates the sudo key and dispatches a function call with `Root` origin.
 		///

substrate/srml/support/src/dispatch.rs

@@ -203,7 +203,7 @@ impl<T> Parameter for T where T: Codec + Clone + Eq {}
 /// * `deposit_event`: Helper function for depositing an [event](https://docs.substrate.dev/docs/event-enum).
 /// The default behavior is to call `deposit_event` from the [System module](../srml_system/index.html).
 /// However, you can write your own implementation for events in your runtime. To use the default behavior,
-/// add `fn deposit_event<T>() = default;` to your `Module`.
+/// add `fn deposit_event() = default;` to your `Module`.
 ///
 /// The following reserved functions also take the block number (with type `T::BlockNumber`) as an optional input:
 ///
@@ -288,7 +288,7 @@ macro_rules! decl_module {
 		{ $( $constants:tt )* }
 		[ $( $dispatchables:tt )* ]
 		$(#[doc = $doc_attr:tt])*
-		$vis:vis fn deposit_event $(<$dpeg:ident $(, $dpeg_instance:ident)?>)* () = default;
+		$vis:vis fn deposit_event() = default;
 		$($rest:tt)*
 	) => {
 		$crate::decl_module!(@normalize
@@ -296,7 +296,7 @@ macro_rules! decl_module {
 			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
 			for enum $call_type where origin: $origin_type, system = $system
 			{ $( $other_where_bounds )* }
-			{ $vis fn deposit_event $(<$dpeg $(, $dpeg_instance)?>)* () = default; }
+			{ $vis fn deposit_event() = default; }
 			{ $( $on_initialize )* }
 			{ $( $on_finalize )* }
 			{ $( $offchain )* }
@@ -317,23 +317,11 @@ macro_rules! decl_module {
 		{ $( $constants:tt )* }
 		[ $( $dispatchables:tt )* ]
 		$(#[doc = $doc_attr:tt])*
-		$vis:vis fn deposit_event $(<$dpeg:ident $(, $dpeg_instance:ident)?>)* (
+		$vis:vis fn deposit_event
-			$($param_name:ident : $param:ty),*
-		) { $( $impl:tt )* }
 		$($rest:tt)*
 	) => {
-		$crate::decl_module!(@normalize
+		compile_error!(
-			$(#[$attr])*
+			"`deposit_event` function is reserved and must follow the syntax: `$vis:vis fn deposit_event() = default;`"
-			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
-			for enum $call_type where origin: $origin_type, system = $system
-			{ $( $other_where_bounds )* }
-			{ $vis fn deposit_event $(<$dpeg $(, $dpeg_instance)?>)* ($( $param_name: $param ),* ) { $( $impl )* } }
-			{ $( $on_initialize )* }
-			{ $( $on_finalize )* }
-			{ $( $offchain )* }
-			{ $( $constants )* }
-			[ $( $dispatchables )* ]
-			$($rest)*
 		);
 	};
 	(@normalize
@@ -685,25 +673,10 @@ macro_rules! decl_module {
 		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?> $module<$trait_instance $(, $instance)?>
 			where $( $other_where_bounds )*
 		{
-			$vis fn deposit_event(event: Event$(<$event_trait_instance $(, $event_instance)?>)?) {
+			$vis fn deposit_event(
-				<$system::Module<$trait_instance>>::deposit_event(
+				event: impl Into<< $trait_instance as $trait_name $(<$instance>)? >::Event>
-					<$trait_instance as $trait_name$(<$instance>)?>::Event::from(event).into()
+			) {
-				);
+				<$system::Module<$trait_instance>>::deposit_event(event.into())
-			}
-		}
-	};
-
-	(@impl_deposit_event
-		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
-		$system:ident;
-		{ $( $other_where_bounds:tt )* }
-		$vis:vis fn deposit_event($param:ident : $param_ty:ty) { $( $impl:tt )* }
-	) => {
-		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?> $module<$trait_instance $(, $instance)?>
-			where $( $other_where_bounds )*
-		{
-			$vis fn deposit_event($param: $param_ty) {
-				$( $impl )*
 			}
 		}
 	};

substrate/srml/support/test/tests/instance.rs

@@ -55,7 +55,7 @@ mod module1 {
 		{
 			fn offchain_worker() {}
 
-			fn deposit_event<T, I>() = default;
+			fn deposit_event() = default;
 
 			fn one(origin) {
 				system::ensure_root(origin)?;
@@ -132,7 +132,7 @@ mod module2 {
 		pub struct Module<T: Trait<I>, I: Instance=DefaultInstance> for enum Call where
 			origin: <T as system::Trait>::Origin
 		{
-			fn deposit_event<T, I>() = default;
+			fn deposit_event() = default;
 		}
 	}
 

substrate/srml/support/test/tests/reserved_keyword/on_initialize.stderr

@@ -38,7 +38,7 @@ error: Invalid call fn name: `offchain_worker`, name is reserved and doesn't mat
    |
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
 
-error: Invalid call fn name: `deposit_event`, name is reserved and doesn't match expected signature, please refer to `decl_module!` documentation to see the appropriate usage, or rename it to an unreserved keyword.
+error: `deposit_event` function is reserved and must follow the syntax: `$vis:vis fn deposit_event() = default;`
   --> $DIR/on_initialize.rs:30:1
    |
 30 | reserved!(on_finalize on_initialize on_finalise on_initialise offchain_worker deposit_event);

substrate/srml/support/test/tests/system.rs

@@ -12,8 +12,11 @@ pub trait Trait: 'static + Eq + Clone {
 
 srml_support::decl_module! {
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
-		pub fn deposit_event(_event: T::Event) {
+	}
-		}
+}
+
+impl<T: Trait> Module<T> {
+	pub fn deposit_event(_event: impl Into<T::Event>) {
 	}
 }
 
@@ -49,4 +52,4 @@ pub fn ensure_root<OuterOrigin, AccountId>(o: OuterOrigin) -> Result<(), &'stati
 	where OuterOrigin: Into<Result<RawOrigin<AccountId>, OuterOrigin>>
 {
 	o.into().map(|_| ()).map_err(|_| "bad origin: expected to be a root origin")
-}
+}

substrate/srml/system/src/lib.rs

@@ -246,11 +246,6 @@ pub type KeyValue = (Vec<u8>, Vec<u8>);
 
 decl_module! {
 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
-		/// Deposits an event into this block's event record.
-		pub fn deposit_event(event: T::Event) {
-			Self::deposit_event_indexed(&[], event);
-		}
-
 		/// A big dispatch that will disallow any other transaction to be included.
 		// TODO: this must be preferable available for testing really (not possible at the moment).
 		#[weight = SimpleDispatchInfo::MaxOperational]
@@ -545,6 +540,11 @@ pub fn ensure_none<OuterOrigin, AccountId>(o: OuterOrigin) -> Result<(), &'stati
 }
 
 impl<T: Trait> Module<T> {
+	/// Deposits an event into this block's event record.
+	pub fn deposit_event(event: impl Into<T::Event>) {
+		Self::deposit_event_indexed(&[], event.into());
+	}
+
 	/// Deposits an event into this block's event record adding this event
 	/// to the corresponding topic indexes.
 	///
@@ -815,7 +815,7 @@ impl<T: Trait> Module<T> {
 		Self::deposit_event(match r {
 			Ok(_) => Event::ExtrinsicSuccess,
 			Err(_) => Event::ExtrinsicFailed,
-		}.into());
+		});
 
 		let next_extrinsic_index = Self::extrinsic_index().unwrap_or_default() + 1u32;
 

substrate/srml/treasury/src/lib.rs

@@ -139,7 +139,7 @@ decl_module! {
 		/// Percentage of spare funds (if any) that are burnt per spend period.
 		const Burn: Permill = T::Burn::get();
 
-		fn deposit_event<T>() = default;
+		fn deposit_event() = default;
 		/// Put forward a suggestion for spending. A deposit proportional to the value
 		/// is reserved and slashed if the proposal is rejected. It is returned once the
 		/// proposal is awarded.