1 files changed, 48 insertions, 0 deletions
diff --git a/third_party/rust/syn/tests/common/parse.rs b/third_party/rust/syn/tests/common/parse.rs
new file mode 100644
index 0000000000..636d0a37a0
--- /dev/null
+++ b/third_party/rust/syn/tests/common/parse.rs
@@ -0,0 +1,48 @@
+extern crate rustc_ast;
+extern crate rustc_expand;
+extern crate rustc_parse as parse;
+extern crate rustc_session;
+extern crate rustc_span;
+
+use rustc_ast::ast;
+use rustc_ast::ptr::P;
+use rustc_session::parse::ParseSess;
+use rustc_span::source_map::FilePathMapping;
+use rustc_span::FileName;
+use std::panic;
+
+pub fn librustc_expr(input: &str) -> Option<P<ast::Expr>> {
+    match panic::catch_unwind(|| {
+        let sess = ParseSess::new(FilePathMapping::empty());
+        let e = parse::new_parser_from_source_str(
+            &sess,
+            FileName::Custom("test_precedence".to_string()),
+            input.to_string(),
+        )
+        .parse_expr();
+        match e {
+            Ok(expr) => Some(expr),
+            Err(mut diagnostic) => {
+                diagnostic.emit();
+                None
+            }
+        }
+    }) {
+        Ok(Some(e)) => Some(e),
+        Ok(None) => None,
+        Err(_) => {
+            errorf!("librustc panicked\n");
+            None
+        }
+    }
+}
+
+pub fn syn_expr(input: &str) -> Option<syn::Expr> {
+    match syn::parse_str(input) {
+        Ok(e) => Some(e),
+        Err(msg) => {
+            errorf!("syn failed to parse\n{:?}\n", msg);
+            None
+        }
+    }
+}