From f4273659a28f2d1f82cc30bbcad69d833383c23d Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 24 Jul 2022 21:34:03 -0700
Subject: [PATCH 1/2] Add test of ineffective TokenStream size_hint

---
 tests/test.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tests/test.rs b/tests/test.rs
index 86031db6..99874e9a 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -547,6 +547,13 @@ fn default_tokenstream_is_empty() {
     assert!(default_token_stream.is_empty());
 }
 
+#[test]
+fn tokenstream_size_hint() {
+    let tokens = "a b (c d) e".parse::<TokenStream>().unwrap();
+
+    assert_eq!(tokens.into_iter().size_hint(), (0, None)); // FIXME
+}
+
 #[test]
 fn tuple_indexing() {
     // This behavior may change depending on https://github.com/rust-lang/rust/pull/71322

From 25a20e06717af8990d3c7c24392f60ab1e355ae2 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 24 Jul 2022 21:12:56 -0700
Subject: [PATCH 2/2] Expose size_hint() for TokenStream's iterator

---
 src/lib.rs    | 4 ++++
 tests/test.rs | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index 5d07b720..e06f0bfa 100644
--- a/src/lib.rs
+++ b/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 {
diff --git a/tests/test.rs b/tests/test.rs
index 99874e9a..31d9a8df 100644
--- a/tests/test.rs
+++ b/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]