1 files changed, 152 insertions, 0 deletions
diff --git a/third_party/rust/syn/tests/test_round_trip.rs b/third_party/rust/syn/tests/test_round_trip.rs
new file mode 100644
index 0000000000..260dd0c3d9
--- /dev/null
+++ b/third_party/rust/syn/tests/test_round_trip.rs
@@ -0,0 +1,152 @@
+#![cfg(not(syn_disable_nightly_tests))]
+#![recursion_limit = "1024"]
+#![feature(rustc_private)]
+
+extern crate rustc_ast;
+extern crate rustc_errors;
+extern crate rustc_expand;
+extern crate rustc_parse as parse;
+extern crate rustc_session;
+extern crate rustc_span;
+
+use quote::quote;
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
+use rustc_ast::ast;
+use rustc_errors::PResult;
+use rustc_session::parse::ParseSess;
+use rustc_span::source_map::FilePathMapping;
+use rustc_span::FileName;
+use walkdir::{DirEntry, WalkDir};
+
+use std::fs::File;
+use std::io::Read;
+use std::panic;
+use std::process;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::time::Instant;
+
+#[macro_use]
+mod macros;
+
+#[allow(dead_code)]
+mod common;
+
+mod repo;
+
+use common::eq::SpanlessEq;
+
+#[test]
+fn test_round_trip() {
+    common::rayon_init();
+    repo::clone_rust();
+    let abort_after = common::abort_after();
+    if abort_after == 0 {
+        panic!("Skipping all round_trip tests");
+    }
+
+    let failed = AtomicUsize::new(0);
+
+    WalkDir::new("tests/rust")
+        .sort_by(|a, b| a.file_name().cmp(b.file_name()))
+        .into_iter()
+        .filter_entry(repo::base_dir_filter)
+        .collect::<Result<Vec<DirEntry>, walkdir::Error>>()
+        .unwrap()
+        .into_par_iter()
+        .for_each(|entry| {
+            let path = entry.path();
+            if path.is_dir() {
+                return;
+            }
+
+            let mut file = File::open(path).unwrap();
+            let mut content = String::new();
+            file.read_to_string(&mut content).unwrap();
+
+            let start = Instant::now();
+            let (krate, elapsed) = match syn::parse_file(&content) {
+                Ok(krate) => (krate, start.elapsed()),
+                Err(msg) => {
+                    errorf!("=== {}: syn failed to parse\n{:?}\n", path.display(), msg);
+                    let prev_failed = failed.fetch_add(1, Ordering::SeqCst);
+                    if prev_failed + 1 >= abort_after {
+                        process::exit(1);
+                    }
+                    return;
+                }
+            };
+            let back = quote!(#krate).to_string();
+            let edition = repo::edition(path).parse().unwrap();
+
+            let equal = panic::catch_unwind(|| {
+                rustc_span::with_session_globals(edition, || {
+                    let sess = ParseSess::new(FilePathMapping::empty());
+                    let before = match librustc_parse(content, &sess) {
+                        Ok(before) => before,
+                        Err(mut diagnostic) => {
+                            diagnostic.cancel();
+                            if diagnostic
+                                .message()
+                                .starts_with("file not found for module")
+                            {
+                                errorf!("=== {}: ignore\n", path.display());
+                            } else {
+                                errorf!(
+                                "=== {}: ignore - librustc failed to parse original content: {}\n",
+                                path.display(),
+                                diagnostic.message()
+                            );
+                            }
+                            return true;
+                        }
+                    };
+                    let after = match librustc_parse(back, &sess) {
+                        Ok(after) => after,
+                        Err(mut diagnostic) => {
+                            errorf!("=== {}: librustc failed to parse", path.display());
+                            diagnostic.emit();
+                            return false;
+                        }
+                    };
+
+                    if SpanlessEq::eq(&before, &after) {
+                        errorf!(
+                            "=== {}: pass in {}ms\n",
+                            path.display(),
+                            elapsed.as_secs() * 1000
+                                + u64::from(elapsed.subsec_nanos()) / 1_000_000
+                        );
+                        true
+                    } else {
+                        errorf!(
+                            "=== {}: FAIL\nbefore: {:#?}\nafter: {:#?}\n",
+                            path.display(),
+                            before,
+                            after,
+                        );
+                        false
+                    }
+                })
+            });
+            match equal {
+                Err(_) => errorf!("=== {}: ignoring librustc panic\n", path.display()),
+                Ok(true) => {}
+                Ok(false) => {
+                    let prev_failed = failed.fetch_add(1, Ordering::SeqCst);
+                    if prev_failed + 1 >= abort_after {
+                        process::exit(1);
+                    }
+                }
+            }
+        });
+
+    let failed = failed.load(Ordering::SeqCst);
+    if failed > 0 {
+        panic!("{} failures", failed);
+    }
+}
+
+fn librustc_parse(content: String, sess: &ParseSess) -> PResult<ast::Crate> {
+    let name = FileName::Custom("test_round_trip".to_string());
+    parse::parse_crate_from_source_str(name, content, sess)
+}