Merge #3800

3800: Introduce ra_proc_macro_srv r=matklad a=edwin0cheng

This PR add preliminary for server side of proc macro : 

1. Add crate setup
2. IO for server side


Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>

crates/ra_proc_macro/src/lib.rs

@@ -11,13 +11,12 @@ pub mod msg;
 
 use process::{ProcMacroProcessSrv, ProcMacroProcessThread};
 use ra_tt::{SmolStr, Subtree};
-use rpc::ProcMacroKind;
 use std::{
     path::{Path, PathBuf},
     sync::Arc,
 };
 
-pub use rpc::{ExpansionResult, ExpansionTask};
+pub use rpc::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask, ProcMacroKind};
 
 #[derive(Debug, Clone)]
 pub struct ProcMacroProcessExpander {

crates/ra_proc_macro_srv/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+edition = "2018"
+name = "ra_proc_macro_srv"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+publish = false
+
+[lib]
+doctest = false
+
+[dependencies]
+ra_tt = { path = "../ra_tt" }
+ra_mbe = { path = "../ra_mbe" }
+ra_proc_macro = { path = "../ra_proc_macro" }
+
+serde_derive = "1.0.104"
+serde = "1.0.104"
+serde_json = "1.0.48"
+libloading = "0.5.2"
+goblin = "0.2.0"
+
+[dev-dependencies]
+cargo_metadata = "0.9.1"
+difference = "2.0.0"

crates/ra_proc_macro_srv/src/lib.rs

@@ -0,0 +1,21 @@
+//! RA Proc Macro Server
+//!
+//! This library is able to call compiled Rust custom derive dynamic libraries on arbitrary code.
+//! The general idea here is based on https://github.com/fedochet/rust-proc-macro-expander.
+//!
+//! But we change some several design for fitting RA needs:
+//!
+//! * We use `ra_tt` for proc-macro `TokenStream` server, it is easy to manipute and interact with
+//!   RA then proc-macro2 token stream.
+//! * By **copying** the whole rustc `lib_proc_macro` code, we are able to build this with `stable`
+//!   rustc rather than `unstable`. (Although in gerenal ABI compatibility is still an issue)
+
+use ra_proc_macro::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask};
+
+pub fn expand_task(_task: &ExpansionTask) -> Result<ExpansionResult, String> {
+    unimplemented!()
+}
+
+pub fn list_macros(_task: &ListMacrosTask) -> Result<ListMacrosResult, String> {
+    unimplemented!()
+}

crates/ra_proc_macro_srv/src/main.rs

@@ -0,0 +1,55 @@
+//! Driver for proc macro server
+
+use ra_proc_macro::msg::{self, Message};
+use ra_proc_macro_srv::{expand_task, list_macros};
+
+use std::io;
+
+fn read_request() -> Result<Option<msg::Request>, io::Error> {
+    let stdin = io::stdin();
+    let mut stdin = stdin.lock();
+    msg::Request::read(&mut stdin)
+}
+
+fn write_response(res: Result<msg::Response, String>) -> Result<(), io::Error> {
+    let msg: msg::Response = match res {
+        Ok(res) => res,
+        Err(err) => msg::Response::Error(msg::ResponseError {
+            code: msg::ErrorCode::ExpansionError,
+            message: err,
+        }),
+    };
+
+    let stdout = io::stdout();
+    let mut stdout = stdout.lock();
+    msg.write(&mut stdout)
+}
+fn main() {
+    loop {
+        let req = match read_request() {
+            Err(err) => {
+                eprintln!("Read message error on ra_proc_macro_srv: {}", err.to_string());
+                continue;
+            }
+            Ok(None) => continue,
+            Ok(Some(req)) => req,
+        };
+
+        match req {
+            msg::Request::ListMacro(task) => {
+                if let Err(err) =
+                    write_response(list_macros(&task).map(|it| msg::Response::ListMacro(it)))
+                {
+                    eprintln!("Write message error on list macro: {}", err);
+                }
+            }
+            msg::Request::ExpansionMacro(task) => {
+                if let Err(err) =
+                    write_response(expand_task(&task).map(|it| msg::Response::ExpansionMacro(it)))
+                {
+                    eprintln!("Write message error on expansion macro: {}", err);
+                }
+            }
+        }
+    }
+}