4 files changed, 89 insertions, 101 deletions

diff --git a/crates/ra_proc_macro/src/lib.rs b/crates/ra_proc_macro/src/lib.rs
index b200fd126..004943b9e 100644
--- a/crates/ra_proc_macro/src/lib.rs
+++ b/crates/ra_proc_macro/src/lib.rs
@@ -2,7 +2,7 @@
 //!
 //! We separate proc-macro expanding logic to an extern program to allow
 //! different implementations (e.g. wasm or dylib loading). And this crate
-//! is used to provide basic infrastructure  for communication between two
+//! is used to provide basic infrastructure for communication between two
 //! processes: Client (RA itself), Server (the external program)
 
 mod rpc;
@@ -13,6 +13,7 @@ use process::{ProcMacroProcessSrv, ProcMacroProcessThread};
 use ra_tt::{SmolStr, Subtree};
 use std::{
     ffi::OsStr,
+    io,
     path::{Path, PathBuf},
     sync::Arc,
 };
@@ -57,14 +58,10 @@ pub struct ProcMacroClient {
 }
 
 impl ProcMacroClient {
-    pub fn extern_process<I, S>(
-        process_path: &Path,
-        args: I,
-    ) -> Result<ProcMacroClient, std::io::Error>
-    where
-        I: IntoIterator<Item = S>,
-        S: AsRef<OsStr>,
-    {
+    pub fn extern_process(
+        process_path: PathBuf,
+        args: impl IntoIterator<Item = impl AsRef<OsStr>>,
+    ) -> io::Result<ProcMacroClient> {
         let (thread, process) = ProcMacroProcessSrv::run(process_path, args)?;
         Ok(ProcMacroClient {
             kind: ProcMacroClientKind::Process { process: Arc::new(process), thread },
@@ -84,7 +81,7 @@ impl ProcMacroClient {
             ProcMacroClientKind::Process { process, .. } => {
                 let macros = match process.find_proc_macros(dylib_path) {
                     Err(err) => {
-                        eprintln!("Fail to find proc macro. Error: {:#?}", err);
+                        eprintln!("Failed to find proc macros. Error: {:#?}", err);
                         return vec![];
                     }
                     Ok(macros) => macros,
diff --git a/crates/ra_proc_macro/src/msg.rs b/crates/ra_proc_macro/src/msg.rs
index aa95bcc8f..95d9b8804 100644
--- a/crates/ra_proc_macro/src/msg.rs
+++ b/crates/ra_proc_macro/src/msg.rs
@@ -1,4 +1,4 @@
-//! Defines messages for cross-process message based on `ndjson` wire protocol
+//! Defines messages for cross-process message passing based on `ndjson` wire protocol
 
 use std::{
     convert::TryFrom,
@@ -31,7 +31,7 @@ macro_rules! impl_try_from_response {
             fn try_from(value: Response) -> Result<Self, Self::Error> {
                 match value {
                     Response::$tag(res) => Ok(res),
-                    _ => Err("Fail to convert from response"),
+                    _ => Err(concat!("Failed to convert response to ", stringify!($tag))),
                 }
             }
         }
@@ -53,18 +53,16 @@ pub enum ErrorCode {
     ExpansionError,
 }
 
-pub trait Message: Sized + Serialize + DeserializeOwned {
-    fn read(r: &mut impl BufRead) -> io::Result<Option<Self>> {
-        let text = match read_json(r)? {
-            None => return Ok(None),
-            Some(text) => text,
-        };
-        let msg = serde_json::from_str(&text)?;
-        Ok(Some(msg))
+pub trait Message: Serialize + DeserializeOwned {
+    fn read(inp: &mut impl BufRead) -> io::Result<Option<Self>> {
+        Ok(match read_json(inp)? {
+            None => None,
+            Some(text) => Some(serde_json::from_str(&text)?),
+        })
     }
-    fn write(self, w: &mut impl Write) -> io::Result<()> {
+    fn write(self, out: &mut impl Write) -> io::Result<()> {
         let text = serde_json::to_string(&self)?;
-        write_json(w, &text)
+        write_json(out, &text)
     }
 }
 
@@ -73,15 +71,12 @@ impl Message for Response {}
 
 fn read_json(inp: &mut impl BufRead) -> io::Result<Option<String>> {
     let mut buf = String::new();
-    if inp.read_line(&mut buf)? == 0 {
-        return Ok(None);
-    }
-    // Remove ending '\n'
-    let buf = &buf[..buf.len() - 1];
-    if buf.is_empty() {
-        return Ok(None);
-    }
-    Ok(Some(buf.to_string()))
+    inp.read_line(&mut buf)?;
+    buf.pop(); // Remove traling '\n'
+    Ok(match buf.len() {
+        0 => None,
+        _ => Some(buf),
+    })
 }
 
 fn write_json(out: &mut impl Write, msg: &str) -> io::Result<()> {
diff --git a/crates/ra_proc_macro/src/process.rs b/crates/ra_proc_macro/src/process.rs
index f851570bc..673f80a7a 100644
--- a/crates/ra_proc_macro/src/process.rs
+++ b/crates/ra_proc_macro/src/process.rs
@@ -9,7 +9,7 @@ use crate::rpc::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTas
 use io::{BufRead, BufReader};
 use std::{
     convert::{TryFrom, TryInto},
-    ffi::OsStr,
+    ffi::{OsStr, OsString},
     io::{self, Write},
     path::{Path, PathBuf},
     process::{Child, Command, Stdio},
@@ -28,66 +28,11 @@ pub(crate) struct ProcMacroProcessThread {
     handle: jod_thread::JoinHandle<()>,
 }
 
-struct Task {
-    req: Request,
-    result_tx: Sender<Option<Response>>,
-}
-
-struct Process {
-    path: PathBuf,
-    child: Child,
-}
-
-impl Drop for Process {
-    fn drop(&mut self) {
-        let _ = self.child.kill();
-    }
-}
-
-impl Process {
-    fn run<I, S>(process_path: &Path, args: I) -> Result<Process, io::Error>
-    where
-        I: IntoIterator<Item = S>,
-        S: AsRef<OsStr>,
-    {
-        let child = Command::new(process_path.clone())
-            .args(args)
-            .stdin(Stdio::piped())
-            .stdout(Stdio::piped())
-            .stderr(Stdio::null())
-            .spawn()?;
-
-        Ok(Process { path: process_path.into(), child })
-    }
-
-    fn restart(&mut self) -> Result<(), io::Error> {
-        let _ = self.child.kill();
-        self.child = Command::new(self.path.clone())
-            .stdin(Stdio::piped())
-            .stdout(Stdio::piped())
-            .stderr(Stdio::null())
-            .spawn()?;
-        Ok(())
-    }
-
-    fn stdio(&mut self) -> Option<(impl Write, impl BufRead)> {
-        let stdin = self.child.stdin.take()?;
-        let stdout = self.child.stdout.take()?;
-        let read = BufReader::new(stdout);
-
-        Some((stdin, read))
-    }
-}
-
 impl ProcMacroProcessSrv {
-    pub fn run<I, S>(
-        process_path: &Path,
-        args: I,
-    ) -> Result<(ProcMacroProcessThread, ProcMacroProcessSrv), io::Error>
-    where
-        I: IntoIterator<Item = S>,
-        S: AsRef<OsStr>,
-    {
+    pub fn run(
+        process_path: PathBuf,
+        args: impl IntoIterator<Item = impl AsRef<OsStr>>,
+    ) -> io::Result<(ProcMacroProcessThread, ProcMacroProcessSrv)> {
         let process = Process::run(process_path, args)?;
 
         let (task_tx, task_rx) = bounded(0);
@@ -197,11 +142,62 @@ fn client_loop(task_rx: Receiver<Task>, mut process: Process) {
     }
 }
 
+struct Task {
+    req: Request,
+    result_tx: Sender<Option<Response>>,
+}
+
+struct Process {
+    path: PathBuf,
+    args: Vec<OsString>,
+    child: Child,
+}
+
+impl Drop for Process {
+    fn drop(&mut self) {
+        let _ = self.child.kill();
+    }
+}
+
+impl Process {
+    fn run(
+        path: PathBuf,
+        args: impl IntoIterator<Item = impl AsRef<OsStr>>,
+    ) -> io::Result<Process> {
+        let args = args.into_iter().map(|s| s.as_ref().into()).collect();
+        let child = mk_child(&path, &args)?;
+        Ok(Process { path, args, child })
+    }
+
+    fn restart(&mut self) -> io::Result<()> {
+        let _ = self.child.kill();
+        self.child = mk_child(&self.path, &self.args)?;
+        Ok(())
+    }
+
+    fn stdio(&mut self) -> Option<(impl Write, impl BufRead)> {
+        let stdin = self.child.stdin.take()?;
+        let stdout = self.child.stdout.take()?;
+        let read = BufReader::new(stdout);
+
+        Some((stdin, read))
+    }
+}
+
+fn mk_child(path: &Path, args: impl IntoIterator<Item = impl AsRef<OsStr>>) -> io::Result<Child> {
+    Command::new(&path)
+        .args(args)
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::null())
+        .spawn()
+}
+
 fn send_request(
     mut writer: &mut impl Write,
     mut reader: &mut impl BufRead,
     req: Request,
-) -> Result<Option<Response>, io::Error> {
+) -> io::Result<Option<Response>> {
     req.write(&mut writer)?;
     Ok(Response::read(&mut reader)?)
 }
diff --git a/crates/ra_proc_macro/src/rpc.rs b/crates/ra_proc_macro/src/rpc.rs
index 66b3f55db..4ce485926 100644
--- a/crates/ra_proc_macro/src/rpc.rs
+++ b/crates/ra_proc_macro/src/rpc.rs
@@ -1,9 +1,9 @@
-//! Data struture serialization related stuffs for RPC
+//! Data struture serialization related stuff for RPC
 //!
-//! Define all necessary rpc serialization data structure,
-//! which include ra_tt related data and some task messages.
-//! Although adding Serialize and Deserialize trait to ra_tt directly seem to be much easier,
-//! we deliberately duplicate the ra_tt struct with #[serde(with = "XXDef")]
+//! Defines all necessary rpc serialization data structures,
+//! which includes `ra_tt` related data and some task messages.
+//! Although adding `Serialize` and `Deserialize` traits to `ra_tt` directly seems
+//! to be much easier, we deliberately duplicate `ra_tt` structs with `#[serde(with = "XXDef")]`
 //! for separation of code responsibility.
 
 use ra_tt::{
@@ -34,15 +34,15 @@ pub struct ListMacrosResult {
 pub struct ExpansionTask {
     /// Argument of macro call.
     ///
-    /// In custom derive that would be a struct or enum; in attribute-like macro - underlying
+    /// In custom derive this will be a struct or enum; in attribute-like macro - underlying
     /// item; in function-like macro - the macro body.
     #[serde(with = "SubtreeDef")]
     pub macro_body: Subtree,
 
-    /// Names of macros to expand.
+    /// Name of macro to expand.
     ///
-    /// In custom derive those are names of derived traits (`Serialize`, `Getters`, etc.). In
-    /// attribute-like and functiona-like macros - single name of macro itself (`show_streams`).
+    /// In custom derive this is the name of the derived trait (`Serialize`, `Getters`, etc.).
+    /// In attribute-like and function-like macros - single name of macro itself (`show_streams`).
     pub macro_name: String,
 
     /// Possible attributes for the attribute-like macros.