From 624c5da1aacf44354dead47dce5033f1806e9228 Mon Sep 17 00:00:00 2001
From: Maximilian Roos <m@maxroos.com>
Date: Fri, 26 Jul 2019 02:58:37 -0400
Subject: [PATCH 1/2] impl Debug for Chars

---
 src/liballoc/tests/str.rs | 10 ++++++++++
 src/libcore/str/mod.rs    | 12 +++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/liballoc/tests/str.rs b/src/liballoc/tests/str.rs
index b197516403f78..20132fea65118 100644
--- a/src/liballoc/tests/str.rs
+++ b/src/liballoc/tests/str.rs
@@ -1108,6 +1108,16 @@ fn test_iterator_last() {
     assert_eq!(it.last(), Some('m'));
 }
 
+#[test]
+fn test_chars_display() {
+    let s = "ศไทย中华Việt Nam";
+    let c = s.chars();
+    assert_eq!(
+        format!("{:?}", c),
+        r#"Chars(['ศ', 'ไ', 'ท', 'ย', '中', '华', 'V', 'i', 'ệ', 't', ' ', 'N', 'a', 'm'])"#
+    );
+}
+
 #[test]
 fn test_bytesator() {
     let s = "ศไทย中华Việt Nam";
diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs
index 4ecaa37460c66..ee791748c1ddf 100644
--- a/src/libcore/str/mod.rs
+++ b/src/libcore/str/mod.rs
@@ -464,7 +464,7 @@ Section: Iterators
 ///
 /// [`chars`]: ../../std/primitive.str.html#method.chars
 /// [`str`]: ../../std/primitive.str.html
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Chars<'a> {
     iter: slice::Iter<'a, u8>
@@ -600,6 +600,16 @@ impl<'a> Iterator for Chars<'a> {
     }
 }
 
+#[stable(feature = "chars_debug_impl", since = "1.38.0")]
+impl<'a> fmt::Debug for Chars<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Chars(")?;
+        f.debug_list().entries(self.clone()).finish()?;
+        write!(f, ")")?;
+        Ok(())
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a> DoubleEndedIterator for Chars<'a> {
     #[inline]

From 3325ff6df47f75cdf4891b35dcaf565f7ffb22cf Mon Sep 17 00:00:00 2001
From: Maximilian Roos <m@maxroos.com>
Date: Mon, 29 Jul 2019 12:26:59 -0400
Subject: [PATCH 2/2] comments from @lzutao

---
 src/liballoc/tests/str.rs | 2 +-
 src/libcore/str/mod.rs    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/liballoc/tests/str.rs b/src/liballoc/tests/str.rs
index 20132fea65118..c5198ca39fedf 100644
--- a/src/liballoc/tests/str.rs
+++ b/src/liballoc/tests/str.rs
@@ -1109,7 +1109,7 @@ fn test_iterator_last() {
 }
 
 #[test]
-fn test_chars_display() {
+fn test_chars_debug() {
     let s = "ศไทย中华Việt Nam";
     let c = s.chars();
     assert_eq!(
diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs
index ee791748c1ddf..4faf9ff4d2ee2 100644
--- a/src/libcore/str/mod.rs
+++ b/src/libcore/str/mod.rs
@@ -601,7 +601,7 @@ impl<'a> Iterator for Chars<'a> {
 }
 
 #[stable(feature = "chars_debug_impl", since = "1.38.0")]
-impl<'a> fmt::Debug for Chars<'a> {
+impl fmt::Debug for Chars<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "Chars(")?;
         f.debug_list().entries(self.clone()).finish()?;