From 87c4bd5a94cb40d49d7cac6e626f24421b5f43ce Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seiichi.uchida@dena.com>
Date: Thu, 26 Jul 2018 21:35:48 +0900
Subject: [PATCH 1/2] Add a test for #2863

---
 tests/source/issue-2863.rs | 25 ++++++++++++++++++
 tests/target/issue-2863.rs | 54 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)
 create mode 100644 tests/source/issue-2863.rs
 create mode 100644 tests/target/issue-2863.rs

diff --git a/tests/source/issue-2863.rs b/tests/source/issue-2863.rs
new file mode 100644
index 00000000000..792ffdbac24
--- /dev/null
+++ b/tests/source/issue-2863.rs
@@ -0,0 +1,25 @@
+// rustfmt-reorder_impl_items: true
+
+impl<T> IntoIterator for SafeVec<T> {
+    existential type F: Trait;
+    type IntoIter = self::IntoIter<T>;
+    type Item = T;
+    // comment on foo()
+    fn foo() {println!("hello, world");}
+    type Bar = u32;
+    fn foo1() {println!("hello, world");}
+    type FooBar = u32;
+    fn foo2() {println!("hello, world");}
+    fn foo3() {println!("hello, world");}
+    const SomeConst: i32 = 100;
+    fn foo4() {println!("hello, world");}
+    fn foo5() {println!("hello, world");}
+    // comment on FoooooBar
+    type FoooooBar = u32;
+    fn foo6() {println!("hello, world");}
+    fn foo7() {println!("hello, world");}
+    type BarFoo = u32;
+    existential type E: Trait;
+    const AnotherConst: i32 = 100;
+    fn foo8() {println!("hello, world");}
+}
diff --git a/tests/target/issue-2863.rs b/tests/target/issue-2863.rs
new file mode 100644
index 00000000000..a53628e3ea9
--- /dev/null
+++ b/tests/target/issue-2863.rs
@@ -0,0 +1,54 @@
+// rustfmt-reorder_impl_items: true
+
+impl<T> IntoIterator for SafeVec<T> {
+    type Bar = u32;
+    type BarFoo = u32;
+    type FooBar = u32;
+    // comment on FoooooBar
+    type FoooooBar = u32;
+    type IntoIter = self::IntoIter<T>;
+    type Item = T;
+
+    existential type E: Trait;
+    existential type F: Trait;
+
+    const AnotherConst: i32 = 100;
+    const SomeConst: i32 = 100;
+
+    // comment on foo()
+    fn foo() {
+        println!("hello, world");
+    }
+
+    fn foo1() {
+        println!("hello, world");
+    }
+
+    fn foo2() {
+        println!("hello, world");
+    }
+
+    fn foo3() {
+        println!("hello, world");
+    }
+
+    fn foo4() {
+        println!("hello, world");
+    }
+
+    fn foo5() {
+        println!("hello, world");
+    }
+
+    fn foo6() {
+        println!("hello, world");
+    }
+
+    fn foo7() {
+        println!("hello, world");
+    }
+
+    fn foo8() {
+        println!("hello, world");
+    }
+}

From 7b37776ade019d8aa6cf86c5bcb2d9f39c0121a5 Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seiichi.uchida@dena.com>
Date: Thu, 26 Jul 2018 21:35:56 +0900
Subject: [PATCH 2/2] Modify the rule for reordering impl items

1. If two items have the same kind, then reorder them based on its ident.
2. Handle existential type.
---
 src/items.rs | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/items.rs b/src/items.rs
index 7da84bfe68f..8c32d393df4 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -591,23 +591,31 @@ impl<'a> FmtVisitor<'a> {
                 buffer.push((self.buffer.clone(), item.clone()));
                 self.buffer.clear();
             }
-            // type -> const -> macro -> method
+            // type -> existential -> const -> macro -> method
             use ast::ImplItemKind::*;
             fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
                 match (a, b) {
-                    (Type(..), Type(..)) | (Const(..), Const(..)) => false,
+                    (Type(..), Type(..))
+                    | (Const(..), Const(..))
+                    | (Existential(..), Existential(..)) => false,
                     _ => true,
                 }
             }
 
             buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
+                (Type(..), Type(..))
+                | (Const(..), Const(..))
+                | (Macro(..), Macro(..))
+                | (Existential(..), Existential(..)) => a.ident.as_str().cmp(&b.ident.as_str()),
+                (Method(..), Method(..)) => a.span.lo().cmp(&b.span.lo()),
                 (Type(..), _) => Ordering::Less,
                 (_, Type(..)) => Ordering::Greater,
+                (Existential(..), _) => Ordering::Less,
+                (_, Existential(..)) => Ordering::Greater,
                 (Const(..), _) => Ordering::Less,
                 (_, Const(..)) => Ordering::Greater,
                 (Macro(..), _) => Ordering::Less,
                 (_, Macro(..)) => Ordering::Greater,
-                _ => a.span.lo().cmp(&b.span.lo()),
             });
             let mut prev_kind = None;
             for (buf, item) in buffer {