---

yaml
---
r: 228273
b: refs/heads/try
c: b0ab164
h: refs/heads/master
i:
  228271: b62e8a0
v: v3

Author: sfackler

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: aca2057ed5fb7af3f8905b2bc01f72fa001c35c8
 refs/heads/snap-stage3: 1af31d4974e33027a68126fa5a5a3c2c6491824f
-refs/heads/try: 0bcbd169310556cfdc7b673df7992ba660ac4d3a
+refs/heads/try: b0ab164b80f8d559cfc96e1d1d3819993672cced
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596
 refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503

branches/try/src/libcore/fmt/builders.rs

@@ -175,6 +175,12 @@ impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
     fn is_pretty(&self) -> bool {
         self.fmt.flags() & (1 << (FlagV1::Alternate as usize)) != 0
     }
+
+    /// Returns the wrapped `Formatter`.
+    #[unstable(feature = "debug_builder_formatter", reason = "recently added")]
+    pub fn formatter(&mut self) -> &mut fmt::Formatter<'b> {
+        &mut self.fmt
+    }
 }
 
 struct DebugInner<'a, 'b: 'a> {

branches/try/src/libcore/fmt/mod.rs

@@ -1490,7 +1490,16 @@ macro_rules! tuple {
             fn fmt(&self, f: &mut Formatter) -> Result {
                 let mut builder = f.debug_tuple("");
                 let ($(ref $name,)*) = *self;
-                $(builder.field($name);)*
+                let mut n = 0;
+                $(
+                    builder.field($name);
+                    n += 1;
+                )*
+
+                if n == 1 {
+                    try!(write!(builder.formatter(), ","));
+                }
+
                 builder.finish()
             }
         }

branches/try/src/libcoretest/tuple.rs

@@ -60,7 +60,7 @@ fn test_tuple_cmp() {
 #[test]
 fn test_show() {
     let s = format!("{:?}", (1,));
-    assert_eq!(s, "(1)");
+    assert_eq!(s, "(1,)");
     let s = format!("{:?}", (1, true));
     assert_eq!(s, "(1, true)");
     let s = format!("{:?}", (1, "hi", true));