Rollup merge of #63000 - max-sixty:chars-display, r=alexcrichton

Impl Debug for Chars

Closes https://github.com/rust-lang/rust/issues/62947, making `Debug` more consistent with the struct's output and purpose

Let me know any feedback!

src/liballoc/tests/str.rs

@@ -1108,6 +1108,16 @@ fn test_iterator_last() {
     assert_eq!(it.last(), Some('m'));
 }
 
+#[test]
+fn test_chars_debug() {
+    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";

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 fmt::Debug for Chars<'_> {
+    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]