Catch panics in round-trip tests

tests/test_round_trip.rs

@@ -77,16 +77,25 @@ fn test(path: &Path, failed: &AtomicUsize, abort_after: usize) {
 
     let content = fs::read_to_string(path).unwrap();
 
-    let start = Instant::now();
-    let (krate, elapsed) = match syn::parse_file(&content) {
-        Ok(krate) => (krate, start.elapsed()),
-        Err(msg) => {
+    let (back, elapsed) = match panic::catch_unwind(|| {
+        let start = Instant::now();
+        let result = syn::parse_file(&content);
+        let elapsed = start.elapsed();
+        result.map(|krate| (quote!(#krate).to_string(), elapsed))
+    }) {
+        Err(_) => {
+            errorf!("=== {}: syn panic\n", path.display());
+            failed();
+            return;
+        }
+        Ok(Err(msg)) => {
             errorf!("=== {}: syn failed to parse\n{:?}\n", path.display(), msg);
             failed();
             return;
         }
+        Ok(Ok(result)) => result,
     };
-    let back = quote!(#krate).to_string();
+
     let edition = repo::edition(path).parse().unwrap();
 
     rustc_span::create_session_if_not_set_then(edition, |_| {