Extract PartialComponents into a type alias (#2767)

Pulling PartialComponents into a named `Service` type stops clippy
complaining about type complexity and also makes the type signatures a
little less scary to read.

There's two instances where we can't pull it out into a type because a
nightly feature has not yet been stabilised (E.g. the `imp Fn` isn't
stabilised in a type alias context here:
https://github.com/paritytech/polkadot-sdk/blob/d84e135bbfc366a17bb6b72d0fc9d09ee781ab8d/polkadot/node/service/src/lib.rs#L477
).

---------

Co-authored-by: Bastian Köcher <git@kchr.de>

cumulus/parachain-template/node/src/service.rs

@@ -59,23 +59,21 @@ type ParachainBackend = TFullBackend<Block>;
 
 type ParachainBlockImport = TParachainBlockImport<Block, Arc<ParachainClient>, ParachainBackend>;
 
+/// Assembly of PartialComponents (enough to run chain ops subcommands)
+pub type Service = PartialComponents<
+	ParachainClient,
+	ParachainBackend,
+	(),
+	sc_consensus::DefaultImportQueue<Block>,
+	sc_transaction_pool::FullPool<Block, ParachainClient>,
+	(ParachainBlockImport, Option<Telemetry>, Option<TelemetryWorkerHandle>),
+>;
+
 /// Starts a `ServiceBuilder` for a full service.
 ///
 /// Use this macro if you don't actually need the full service, but just the builder in order to
 /// be able to perform chain operations.
-pub fn new_partial(
+pub fn new_partial(config: &Configuration) -> Result<Service, sc_service::Error> {
-	config: &Configuration,
-) -> Result<
-	PartialComponents<
-		ParachainClient,
-		ParachainBackend,
-		(),
-		sc_consensus::DefaultImportQueue<Block>,
-		sc_transaction_pool::FullPool<Block, ParachainClient>,
-		(ParachainBlockImport, Option<Telemetry>, Option<TelemetryWorkerHandle>),
-	>,
-	sc_service::Error,
-> {
 	let telemetry = config
 		.telemetry_endpoints
 		.clone()

cumulus/polkadot-parachain/src/service.rs

@@ -216,6 +216,16 @@ impl sc_executor::NativeExecutionDispatch for PeopleRococoRuntimeExecutor {
 	}
 }
 
+/// Assembly of PartialComponents (enough to run chain ops subcommands)
+pub type Service<RuntimeApi> = PartialComponents<
+	ParachainClient<RuntimeApi>,
+	ParachainBackend,
+	(),
+	sc_consensus::DefaultImportQueue<Block>,
+	sc_transaction_pool::FullPool<Block, ParachainClient<RuntimeApi>>,
+	(ParachainBlockImport<RuntimeApi>, Option<Telemetry>, Option<TelemetryWorkerHandle>),
+>;
+
 /// Starts a `ServiceBuilder` for a full service.
 ///
 /// Use this macro if you don't actually need the full service, but just the builder in order to
@@ -223,17 +233,7 @@ impl sc_executor::NativeExecutionDispatch for PeopleRococoRuntimeExecutor {
 pub fn new_partial<RuntimeApi, BIQ>(
 	config: &Configuration,
 	build_import_queue: BIQ,
-) -> Result<
+) -> Result<Service<RuntimeApi>, sc_service::Error>
-	PartialComponents<
-		ParachainClient<RuntimeApi>,
-		ParachainBackend,
-		(),
-		sc_consensus::DefaultImportQueue<Block>,
-		sc_transaction_pool::FullPool<Block, ParachainClient<RuntimeApi>>,
-		(ParachainBlockImport<RuntimeApi>, Option<Telemetry>, Option<TelemetryWorkerHandle>),
-	>,
-	sc_service::Error,
->
 where
 	RuntimeApi: ConstructRuntimeApi<Block, ParachainClient<RuntimeApi>> + Send + Sync + 'static,
 	RuntimeApi::RuntimeApi: sp_transaction_pool::runtime_api::TaggedTransactionQueue<Block>

cumulus/test/service/src/lib.rs

@@ -183,6 +183,16 @@ impl RecoveryHandle for FailingRecoveryHandle {
 	}
 }
 
+/// Assembly of PartialComponents (enough to run chain ops subcommands)
+pub type Service = PartialComponents<
+	Client,
+	Backend,
+	(),
+	sc_consensus::import_queue::BasicQueue<Block>,
+	sc_transaction_pool::FullPool<Block, Client>,
+	ParachainBlockImport,
+>;
+
 /// Starts a `ServiceBuilder` for a full service.
 ///
 /// Use this macro if you don't actually need the full service, but just the builder in order to
@@ -190,17 +200,7 @@ impl RecoveryHandle for FailingRecoveryHandle {
 pub fn new_partial(
 	config: &mut Configuration,
 	enable_import_proof_record: bool,
-) -> Result<
+) -> Result<Service, sc_service::Error> {
-	PartialComponents<
-		Client,
-		Backend,
-		(),
-		sc_consensus::import_queue::BasicQueue<Block>,
-		sc_transaction_pool::FullPool<Block, Client>,
-		ParachainBlockImport,
-	>,
-	sc_service::Error,
-> {
 	let heap_pages = config
 		.default_heap_pages
 		.map_or(DEFAULT_HEAP_ALLOC_STRATEGY, |h| HeapAllocStrategy::Static { extra_pages: h as _ });

prdoc/pr_2767.prdoc

@@ -0,0 +1,17 @@
+# 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: Extract PartialComponents into type alias `Service`
+
+doc:
+  - audience: Node Dev
+    description: |
+      Simplifies service definitions by extraction of a complicated type into a type alias. No breaking changes.
+
+crates:
+  - name: "sc-service"
+  - name: "node-template"
+  - name: "minimal-node"
+  - name: "cumulus-test-service"
+  - name: "polkadot-parachain-bin"
+  - name: "parachain-template-node"

substrate/bin/minimal/node/src/service.rs

@@ -38,19 +38,17 @@ pub(crate) type FullClient =
 type FullBackend = sc_service::TFullBackend<Block>;
 type FullSelectChain = sc_consensus::LongestChain<FullBackend, Block>;
 
-pub fn new_partial(
+/// Assembly of PartialComponents (enough to run chain ops subcommands)
-	config: &Configuration,
+pub type Service = sc_service::PartialComponents<
-) -> Result<
+	FullClient,
-	sc_service::PartialComponents<
+	FullBackend,
-		FullClient,
+	FullSelectChain,
-		FullBackend,
+	sc_consensus::DefaultImportQueue<Block>,
-		FullSelectChain,
+	sc_transaction_pool::FullPool<Block, FullClient>,
-		sc_consensus::DefaultImportQueue<Block>,
+	Option<Telemetry>,
-		sc_transaction_pool::FullPool<Block, FullClient>,
+>;
-		Option<Telemetry>,
+
-	>,
+pub fn new_partial(config: &Configuration) -> Result<Service, ServiceError> {
-	ServiceError,
-> {
 	let telemetry = config
 		.telemetry_endpoints
 		.clone()

substrate/bin/node-template/node/src/service.rs

@@ -23,29 +23,20 @@ type FullSelectChain = sc_consensus::LongestChain<FullBackend, Block>;
 /// imported and generated.
 const GRANDPA_JUSTIFICATION_PERIOD: u32 = 512;
 
-#[allow(clippy::type_complexity)]
+pub type Service = sc_service::PartialComponents<
-pub fn new_partial(
+	FullClient,
-	config: &Configuration,
+	FullBackend,
-) -> Result<
+	FullSelectChain,
-	sc_service::PartialComponents<
+	sc_consensus::DefaultImportQueue<Block>,
-		FullClient,
+	sc_transaction_pool::FullPool<Block, FullClient>,
-		FullBackend,
+	(
-		FullSelectChain,
+		sc_consensus_grandpa::GrandpaBlockImport<FullBackend, Block, FullClient, FullSelectChain>,
-		sc_consensus::DefaultImportQueue<Block>,
+		sc_consensus_grandpa::LinkHalf<Block, FullClient, FullSelectChain>,
-		sc_transaction_pool::FullPool<Block, FullClient>,
+		Option<Telemetry>,
-		(
+	),
-			sc_consensus_grandpa::GrandpaBlockImport<
+>;
-				FullBackend,
+
-				Block,
+pub fn new_partial(config: &Configuration) -> Result<Service, ServiceError> {
-				FullClient,
-				FullSelectChain,
-			>,
-			sc_consensus_grandpa::LinkHalf<Block, FullClient, FullSelectChain>,
-			Option<Telemetry>,
-		),
-	>,
-	ServiceError,
-> {
 	let telemetry = config
 		.telemetry_endpoints
 		.clone()