Expunge error-chain (feat. tomaka) (#2662)

* Remove error_chain

* Expunge error-chain from rpc and service.

* Expunge from transaction pool.

* Expunge from node/cli

* Expunge from keystore.

* Remove some boilerplate.

* Fix remaining stuff.

* Improve on deprecation message.

* Fix issues.

* Fix trnsaction pool tests.

* Fix the rest.

* Fix borked merge.

* Update lock

substrate/core/service/src/components.rs

@@ -522,7 +522,7 @@ impl<Factory: ServiceFactory> Components for FullComponents<Factory> {
 		select_chain: Option<Self::SelectChain>,
 	) -> Result<Self::ImportQueue, error::Error> {
 		let select_chain = select_chain
-			.ok_or_else(|| error::Error::from(error::ErrorKind::SelectChainRequired))?;
+			.ok_or(error::Error::SelectChainRequired)?;
 		Factory::build_full_import_queue(config, client, select_chain)
 	}
 

substrate/core/service/src/error.rs

@@ -16,32 +16,49 @@
 
 //! Errors that can occur during the service operation.
 
-// Silence: `use of deprecated item 'std::error::Error::cause': replaced by Error::source, which can support downcasting`
-// https://github.com/paritytech/substrate/issues/1547
-#![allow(deprecated)]
-
 use client;
 use network;
 use keystore;
 use consensus_common;
-use error_chain::*;
 
-error_chain! {
-	foreign_links {
-		Client(client::error::Error) #[doc="Client error"];
-		Io(::std::io::Error) #[doc="IO error"];
+/// Service Result typedef.
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// Service errors.
+#[derive(Debug, derive_more::Display, derive_more::From)]
+pub enum Error {
+	/// Client error.
+	Client(client::error::Error),
+	/// IO error.
+	Io(std::io::Error),
+	/// Consensus error.
+	Consensus(consensus_common::Error),
+	/// Network error.
+	Network(network::error::Error),
+	/// Keystore error.
+	Keystore(keystore::Error),
+	/// Best chain selection strategy is missing.
+	#[display(fmt="Best chain selection strategy (SelectChain) is not provided.")]
+	SelectChainRequired,
+	/// Other error.
+	Other(String),
+}
+
+impl<'a> From<&'a str> for Error {
+	fn from(s: &'a str) -> Self {
+		Error::Other(s.into())
 	}
+}
 
-	links {
-		Consensus(consensus_common::Error, consensus_common::ErrorKind) #[doc="Consensus error"];
-		Network(network::error::Error, network::error::ErrorKind) #[doc="Network error"];
-		Keystore(keystore::Error, keystore::ErrorKind) #[doc="Keystore error"];
-	}
-
-	errors {
-		SelectChainRequired {
-			description("Best chain selection strategy (SelectChain) must be provided when starting full node or authority."),
-			display("Best chain selection strategy (SelectChain) is not provided."),
+impl std::error::Error for Error {
+	fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+		match self {
+			Error::Client(ref err) => Some(err),
+			Error::Io(ref err) => Some(err),
+			Error::Consensus(ref err) => Some(err),
+			Error::Network(ref err) => Some(err),
+			Error::Keystore(ref err) => Some(err),
+			_ => None,
 		}
 	}
 }

substrate/core/service/src/lib.rs

@@ -44,7 +44,7 @@ use runtime_primitives::traits::{Header, SaturatedConversion};
 use substrate_executor::NativeExecutor;
 use tel::{telemetry, SUBSTRATE_INFO};
 
-pub use self::error::{ErrorKind, Error};
+pub use self::error::Error;
 pub use config::{Configuration, Roles, PruningMode};
 pub use chain_spec::{ChainSpec, Properties};
 pub use transaction_pool::txpool::{
@@ -515,7 +515,7 @@ impl<C: Components> network::TransactionPool<ComponentExHash<C>, ComponentBlock<
 			match self.pool.submit_one(&best_block_id, uxt) {
 				Ok(hash) => Some(hash),
 				Err(e) => match e.into_pool_error() {
-					Ok(txpool::error::Error(txpool::error::ErrorKind::AlreadyImported(hash), _)) => {
+					Ok(txpool::error::Error::AlreadyImported(hash)) => {
 						hash.downcast::<ComponentExHash<C>>().ok()
 							.map(|x| x.as_ref().clone())
 					},