add sub errors to SubSystemError

node/subsystem/Cargo.toml

@@ -21,6 +21,7 @@ polkadot-statement-table = { path = "../../statement-table" }
 sc-network = { git = "https://github.com/paritytech/substrate", branch = "master" }
 smallvec = "1.4.1"
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master" }
+thiserror = "1.0.21"
 
 [dev-dependencies]
 assert_matches = "1.3.0"

node/subsystem/src/lib.rs

@@ -105,19 +105,30 @@ pub enum FromOverseer<M> {
 	},
 }
 
+
+use thiserror::Error;
 /// An error type that describes faults that may happen
 ///
 /// These are:
 ///   * Channels being closed
 ///   * Subsystems dying when they are not expected to
 ///   * Subsystems not dying when they are told to die
 ///   * etc.
-#[derive(Debug, PartialEq, Eq)]
-pub struct SubsystemError;
+#[derive(Error, Debug, PartialEq, Eq)]
+pub enum SubsystemError {
+	#[error(transparent)]
+	NotifyCancellation(#[from] oneshot::Canceled),
+	#[error(transparent)]
+	QueueError(#[from] mpsc::SendError),
+	#[error(transparent)]
+	TaskSpawn(#[from] futures::task::SpawnError),
+	#[error(transparent)]
+	Infallible(#[from] std::convert::Infallible),
+}
 
 impl From<mpsc::SendError> for SubsystemError {
-	fn from(_: mpsc::SendError) -> Self {
-		Self
+	fn from(error: mpsc::SendError) -> Self {
+		Self::Queue()
 	}
 }