Add clippy to CI and fix several clippy warnings (#625)

* Remove ambiguity when using deps
* Fix doc and some linting hints
* Make tests more readable
* Run clippy during the CI checks
* Fix formatting
* A few more linting fixes
* Remove old comment

.gitlab-ci.yml

@@ -45,8 +45,9 @@ checkstyle-linux-stable:
   <<:                              *only
   <<:                              *docker-env
   script:
-    - rustup component add rustfmt
+    - rustup component add rustfmt clippy
     - cargo fmt --all -- --check
+    - cargo clippy
   allow_failure:                   true
 
 # test rust stable

core-client/transports/src/lib.rs

@@ -178,7 +178,7 @@ impl<T: DeserializeOwned + Unpin + 'static> Stream for TypedSubscriptionStream<T
 					.map_err(|error| RpcError::ParseError(self.returns.into(), Box::new(error))),
 			),
 			None => None,
-			Some(Err(err)) => Some(Err(err.into())),
+			Some(Err(err)) => Some(Err(err)),
 		}
 		.into()
 	}

core-client/transports/src/transports/duplex.rs

@@ -281,7 +281,7 @@ where
 			}
 			match self.outgoing.pop_front() {
 				Some(request) => {
-					if let Err(_) = self.sink.as_mut().start_send(request) {
+					if self.sink.as_mut().start_send(request).is_err() {
 						// the channel is disconnected.
 						return err().into();
 					}

core-client/transports/src/transports/mod.rs

@@ -151,7 +151,7 @@ impl From<ClientResponse> for Result<Value, Error> {
 						(Some(_), _, Some(error)) => {
 							let error = serde_json::from_value::<Error>(error.to_owned())
 								.ok()
-								.unwrap_or_else(|| Error::parse_error());
+								.unwrap_or_else(Error::parse_error);
 							Err(error)
 						}
 						_ => Ok(n.params.into()),

core/src/io.rs

@@ -8,7 +8,6 @@ use std::pin::Pin;
 use std::sync::Arc;
 
 use futures_util::{self, future, FutureExt};
-use serde_json;
 
 use crate::calls::{
 	Metadata, RemoteProcedure, RpcMethod, RpcMethodSimple, RpcMethodSync, RpcNotification, RpcNotificationSimple,
@@ -60,10 +59,10 @@ impl Default for Compatibility {
 
 impl Compatibility {
 	fn is_version_valid(self, version: Option<Version>) -> bool {
-		match (self, version) {
-			(Compatibility::V1, None) | (Compatibility::V2, Some(Version::V2)) | (Compatibility::Both, _) => true,
-			_ => false,
-		}
+		matches!(
+			(self, version),
+			(Compatibility::V1, None) | (Compatibility::V2, Some(Version::V2)) | (Compatibility::Both, _)
+		)
 	}
 
 	fn default_version(self) -> Option<Version> {
@@ -208,10 +207,7 @@ impl<T: Metadata, S: Middleware<T>> MetaIoHandler<T, S> {
 		use self::future::Either::{Left, Right};
 		fn as_string(response: Option<Response>) -> Option<String> {
 			let res = response.map(write_response);
-			debug!(target: "rpc", "Response: {}.", match res {
-				Some(ref res) => res,
-				None => "None",
-			});
+			debug!(target: "rpc", "Response: {}.", res.as_ref().unwrap_or(&"None".to_string()));
 			res
 		}
 
@@ -237,7 +233,7 @@ impl<T: Metadata, S: Middleware<T>> MetaIoHandler<T, S> {
 		}
 
 		fn outputs_as_batch(outs: Vec<Option<Output>>) -> Option<Response> {
-			let outs: Vec<_> = outs.into_iter().filter_map(|v| v).collect();
+			let outs: Vec<_> = outs.into_iter().flatten().collect();
 			if outs.is_empty() {
 				None
 			} else {

core/src/lib.rs

@@ -3,19 +3,17 @@
 //! Right now it supports only server side handling requests.
 //!
 //! ```rust
-//! use jsonrpc_core::*;
+//! use jsonrpc_core::IoHandler;
+//! use jsonrpc_core::Value;
+//! let mut io = IoHandler::new();
+//! io.add_sync_method("say_hello", |_| {
+//!     Ok(Value::String("Hello World!".into()))
+//! });
 //!
-//! fn main() {
-//! 	let mut io = IoHandler::new();
-//! 	io.add_sync_method("say_hello", |_| {
-//!			Ok(Value::String("Hello World!".into()))
-//! 	});
+//! let request = r#"{"jsonrpc": "2.0", "method": "say_hello", "params": [42, 23], "id": 1}"#;
+//! let response = r#"{"jsonrpc":"2.0","result":"Hello World!","id":1}"#;
 //!
-//! 	let request = r#"{"jsonrpc": "2.0", "method": "say_hello", "params": [42, 23], "id": 1}"#;
-//! 	let response = r#"{"jsonrpc":"2.0","result":"Hello World!","id":1}"#;
-//!
-//! 	assert_eq!(io.handle_request_sync(request), Some(response.to_string()));
-//! }
+//! assert_eq!(io.handle_request_sync(request), Some(response.to_string()));
 //! ```
 
 #![deny(missing_docs)]

core/src/types/params.rs

@@ -1,7 +1,6 @@
 //! jsonrpc params field
 
 use serde::de::DeserializeOwned;
-use serde_json;
 use serde_json::value::from_value;
 
 use super::{Error, Value};

core/src/types/response.rs

@@ -43,8 +43,8 @@ impl Output {
 	/// Creates new output given `Result`, `Id` and `Version`.
 	pub fn from(result: CoreResult<Value>, id: Id, jsonrpc: Option<Version>) -> Self {
 		match result {
-			Ok(result) => Output::Success(Success { id, jsonrpc, result }),
-			Err(error) => Output::Failure(Failure { id, jsonrpc, error }),
+			Ok(result) => Output::Success(Success { jsonrpc, result, id }),
+			Err(error) => Output::Failure(Failure { jsonrpc, error, id }),
 		}
 	}