1 files changed, 170 insertions, 0 deletions
diff --git a/third_party/rust/syn/benches/rust.rs b/third_party/rust/syn/benches/rust.rs
new file mode 100644
index 0000000000..e3f8f550ab
--- /dev/null
+++ b/third_party/rust/syn/benches/rust.rs
@@ -0,0 +1,170 @@
+// $ cargo bench --features full,test --bench rust
+//
+// Syn only, useful for profiling:
+// $ RUSTFLAGS='--cfg syn_only' cargo build --release --features full,test --bench rust
+
+#![cfg_attr(not(syn_only), feature(rustc_private))]
+#![recursion_limit = "1024"]
+#![allow(clippy::cast_lossless, clippy::unnecessary_wraps)]
+
+#[macro_use]
+#[path = "../tests/macros/mod.rs"]
+mod macros;
+
+#[path = "../tests/common/mod.rs"]
+mod common;
+#[path = "../tests/repo/mod.rs"]
+mod repo;
+
+use std::fs;
+use std::time::{Duration, Instant};
+
+#[cfg(not(syn_only))]
+mod tokenstream_parse {
+    use proc_macro2::TokenStream;
+    use std::str::FromStr;
+
+    pub fn bench(content: &str) -> Result<(), ()> {
+        TokenStream::from_str(content).map(drop).map_err(drop)
+    }
+}
+
+mod syn_parse {
+    pub fn bench(content: &str) -> Result<(), ()> {
+        syn::parse_file(content).map(drop).map_err(drop)
+    }
+}
+
+#[cfg(not(syn_only))]
+mod librustc_parse {
+    extern crate rustc_data_structures;
+    extern crate rustc_error_messages;
+    extern crate rustc_errors;
+    extern crate rustc_parse;
+    extern crate rustc_session;
+    extern crate rustc_span;
+
+    use rustc_data_structures::sync::Lrc;
+    use rustc_error_messages::FluentBundle;
+    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};
+
+    pub fn bench(content: &str) -> Result<(), ()> {
+        struct SilentEmitter;
+
+        impl Emitter for SilentEmitter {
+            fn emit_diagnostic(&mut self, _diag: &Diagnostic) {}
+            fn source_map(&self) -> Option<&Lrc<SourceMap>> {
+                None
+            }
+        }
+
+        impl Translate for SilentEmitter {
+            fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>> {
+                None
+            }
+            fn fallback_fluent_bundle(&self) -> &FluentBundle {
+                panic!("silent emitter attempted to translate a diagnostic");
+            }
+        }
+
+        rustc_span::create_session_if_not_set_then(Edition::Edition2018, |_| {
+            let cm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
+            let emitter = Box::new(SilentEmitter);
+            let handler = Handler::with_emitter(false, None, emitter);
+            let sess = ParseSess::with_span_handler(handler, cm);
+            if let Err(diagnostic) = rustc_parse::parse_crate_from_source_str(
+                FileName::Custom("bench".to_owned()),
+                content.to_owned(),
+                &sess,
+            ) {
+                diagnostic.cancel();
+                return Err(());
+            };
+            Ok(())
+        })
+    }
+}
+
+#[cfg(not(syn_only))]
+mod read_from_disk {
+    pub fn bench(content: &str) -> Result<(), ()> {
+        _ = content;
+        Ok(())
+    }
+}
+
+fn exec(mut codepath: impl FnMut(&str) -> Result<(), ()>) -> Duration {
+    let begin = Instant::now();
+    let mut success = 0;
+    let mut total = 0;
+
+    walkdir::WalkDir::new("tests/rust/src")
+        .into_iter()
+        .filter_entry(repo::base_dir_filter)
+        .for_each(|entry| {
+            let entry = entry.unwrap();
+            let path = entry.path();
+            if path.is_dir() {
+                return;
+            }
+            let content = fs::read_to_string(path).unwrap();
+            let ok = codepath(&content).is_ok();
+            success += ok as usize;
+            total += 1;
+            if !ok {
+                eprintln!("FAIL {}", path.display());
+            }
+        });
+
+    assert_eq!(success, total);
+    begin.elapsed()
+}
+
+fn main() {
+    repo::clone_rust();
+
+    macro_rules! testcases {
+        ($($(#[$cfg:meta])* $name:ident,)*) => {
+            [
+                $(
+                    $(#[$cfg])*
+                    (stringify!($name), $name::bench as fn(&str) -> Result<(), ()>),
+                )*
+            ]
+        };
+    }
+
+    #[cfg(not(syn_only))]
+    {
+        let mut lines = 0;
+        let mut files = 0;
+        exec(|content| {
+            lines += content.lines().count();
+            files += 1;
+            Ok(())
+        });
+        eprintln!("\n{} lines in {} files", lines, files);
+    }
+
+    for (name, f) in testcases!(
+        #[cfg(not(syn_only))]
+        read_from_disk,
+        #[cfg(not(syn_only))]
+        tokenstream_parse,
+        syn_parse,
+        #[cfg(not(syn_only))]
+        librustc_parse,
+    ) {
+        eprint!("{:20}", format!("{}:", name));
+        let elapsed = exec(f);
+        eprintln!(
+            "elapsed={}.{:03}s",
+            elapsed.as_secs(),
+            elapsed.subsec_millis(),
+        );
+    }
+    eprintln!();
+}