Expose size_hint() for TokenStream's iterator

Author: dtolnay

src/lib.rs

@@ -1290,6 +1290,10 @@ pub mod token_stream {
         fn next(&mut self) -> Option<TokenTree> {
             self.inner.next()
         }
+
+        fn size_hint(&self) -> (usize, Option<usize>) {
+            self.inner.size_hint()
+        }
     }
 
     impl Debug for IntoIter {

tests/test.rs

@@ -551,7 +551,7 @@ fn default_tokenstream_is_empty() {
 fn tokenstream_size_hint() {
     let tokens = "a b (c d) e".parse::<TokenStream>().unwrap();
 
-    assert_eq!(tokens.into_iter().size_hint(), (0, None)); // FIXME
+    assert_eq!(tokens.into_iter().size_hint(), (4, Some(4)));
 }
 
 #[test]