2 files changed, 37 insertions, 10 deletions

diff --git a/vendor/syn/benches/file.rs b/vendor/syn/benches/file.rs
index 86204df2d..bd4a247df 100644
--- a/vendor/syn/benches/file.rs
+++ b/vendor/syn/benches/file.rs
@@ -1,8 +1,12 @@
-// $ cargo bench --features full --bench file
+// $ cargo bench --features full,test --bench file
 
 #![feature(rustc_private, test)]
 #![recursion_limit = "1024"]
-#![allow(clippy::missing_panics_doc, clippy::must_use_candidate)]
+#![allow(
+    clippy::items_after_statements,
+    clippy::missing_panics_doc,
+    clippy::must_use_candidate
+)]
 
 extern crate test;
 
@@ -15,17 +19,37 @@ mod common;
 #[path = "../tests/repo/mod.rs"]
 pub mod repo;
 
-use proc_macro2::TokenStream;
+use proc_macro2::{Span, TokenStream};
 use std::fs;
 use std::str::FromStr;
+use syn::parse::{ParseStream, Parser};
 use test::Bencher;
 
 const FILE: &str = "tests/rust/library/core/src/str/mod.rs";
 
-#[bench]
-fn parse_file(b: &mut Bencher) {
+fn get_tokens() -> TokenStream {
     repo::clone_rust();
     let content = fs::read_to_string(FILE).unwrap();
-    let tokens = TokenStream::from_str(&content).unwrap();
+    TokenStream::from_str(&content).unwrap()
+}
+
+#[bench]
+fn baseline(b: &mut Bencher) {
+    let tokens = get_tokens();
+    b.iter(|| drop(tokens.clone()));
+}
+
+#[bench]
+fn create_token_buffer(b: &mut Bencher) {
+    let tokens = get_tokens();
+    fn immediate_fail(_input: ParseStream) -> syn::Result<()> {
+        Err(syn::Error::new(Span::call_site(), ""))
+    }
+    b.iter(|| immediate_fail.parse2(tokens.clone()));
+}
+
+#[bench]
+fn parse_file(b: &mut Bencher) {
+    let tokens = get_tokens();
     b.iter(|| syn::parse2::<syn::File>(tokens.clone()));
 }
diff --git a/vendor/syn/benches/rust.rs b/vendor/syn/benches/rust.rs
index 5e4fba182..e3f8f550a 100644
--- a/vendor/syn/benches/rust.rs
+++ b/vendor/syn/benches/rust.rs
@@ -1,7 +1,7 @@
-// $ cargo bench --features full --bench rust
+// $ cargo bench --features full,test --bench rust
 //
 // Syn only, useful for profiling:
-// $ RUSTFLAGS='--cfg syn_only' cargo build --release --features full --bench rust
+// $ RUSTFLAGS='--cfg syn_only' cargo build --release --features full,test --bench rust
 
 #![cfg_attr(not(syn_only), feature(rustc_private))]
 #![recursion_limit = "1024"]
@@ -46,7 +46,7 @@ mod librustc_parse {
 
     use rustc_data_structures::sync::Lrc;
     use rustc_error_messages::FluentBundle;
-    use rustc_errors::{emitter::Emitter, Diagnostic, Handler};
+    use rustc_errors::{emitter::Emitter, translation::Translate, Diagnostic, Handler};
     use rustc_session::parse::ParseSess;
     use rustc_span::source_map::{FilePathMapping, SourceMap};
     use rustc_span::{edition::Edition, FileName};
@@ -59,6 +59,9 @@ mod librustc_parse {
             fn source_map(&self) -> Option<&Lrc<SourceMap>> {
                 None
             }
+        }
+
+        impl Translate for SilentEmitter {
             fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>> {
                 None
             }
@@ -88,7 +91,7 @@ mod librustc_parse {
 #[cfg(not(syn_only))]
 mod read_from_disk {
     pub fn bench(content: &str) -> Result<(), ()> {
-        let _ = content;
+        _ = content;
         Ok(())
     }
 }