2 files changed, 13 insertions, 3 deletions

diff --git a/crates/proc_macro_srv/src/cli.rs b/crates/proc_macro_srv/src/cli.rs
index d428b9567..bc48f1c43 100644
--- a/crates/proc_macro_srv/src/cli.rs
+++ b/crates/proc_macro_srv/src/cli.rs
@@ -6,8 +6,9 @@ use std::io;
 
 pub fn run() -> io::Result<()> {
     let mut srv = ProcMacroSrv::default();
+    let mut buf = String::new();
 
-    while let Some(req) = read_request()? {
+    while let Some(req) = read_request(&mut buf)? {
         let res = match req {
             msg::Request::ListMacro(task) => srv.list_macros(&task).map(msg::Response::ListMacro),
             msg::Request::ExpansionMacro(task) => {
@@ -30,8 +31,8 @@ pub fn run() -> io::Result<()> {
     Ok(())
 }
 
-fn read_request() -> io::Result<Option<msg::Request>> {
-    msg::Request::read(&mut io::stdin().lock())
+fn read_request(buf: &mut String) -> io::Result<Option<msg::Request>> {
+    msg::Request::read(&mut io::stdin().lock(), buf)
 }
 
 fn write_response(msg: msg::Response) -> io::Result<()> {
diff --git a/crates/proc_macro_srv/src/rustc_server.rs b/crates/proc_macro_srv/src/rustc_server.rs
index ceefd187d..c147484c0 100644
--- a/crates/proc_macro_srv/src/rustc_server.rs
+++ b/crates/proc_macro_srv/src/rustc_server.rs
@@ -805,5 +805,14 @@ mod tests {
         let t2 = TokenStream::from_str("(a);").unwrap();
         assert_eq!(t2.token_trees.len(), 2);
         assert_eq!(t2.token_trees[0], subtree_paren_a);
+
+        let underscore = TokenStream::from_str("_").unwrap();
+        assert_eq!(
+            underscore.token_trees[0],
+            tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
+                text: "_".into(),
+                id: tt::TokenId::unspecified(),
+            }))
+        );
     }
 }