Merge pull request #1646 from dtolnay/unwindsafe

Make ParseBuffer unwindsafe

src/parse.rs

@@ -197,6 +197,7 @@ use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem;
 use std::ops::Deref;
+use std::panic::{RefUnwindSafe, UnwindSafe};
 use std::rc::Rc;
 use std::str::FromStr;
 
@@ -283,6 +284,9 @@ impl<'a> Debug for ParseBuffer<'a> {
     }
 }
 
+impl<'a> UnwindSafe for ParseBuffer<'a> {}
+impl<'a> RefUnwindSafe for ParseBuffer<'a> {}
+
 /// Cursor state associated with speculative parsing.
 ///
 /// This type is the input of the closure provided to [`ParseStream::step`].

tests/test_parse_buffer.rs

@@ -1,6 +1,7 @@
 #![allow(clippy::non_ascii_literal)]
 
-use proc_macro2::{Delimiter, Group, Punct, Spacing, TokenStream, TokenTree};
+use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, TokenStream, TokenTree};
+use std::panic;
 use syn::parse::discouraged::Speculative as _;
 use syn::parse::{Parse, ParseStream, Parser, Result};
 use syn::{parenthesized, Token};
@@ -90,3 +91,13 @@ fn trailing_empty_none_group() {
 
     parse.parse2(tokens).unwrap();
 }
+
+#[test]
+fn test_unwind_safe() {
+    fn parse(input: ParseStream) -> Result<Ident> {
+        let thread_result = panic::catch_unwind(|| input.parse());
+        thread_result.unwrap()
+    }
+
+    parse.parse_str("throw").unwrap();
+}