From b2d3daccfa882185cc5565ca82861babc1f64dd2 Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Thu, 8 Mar 2018 19:08:32 +0900
Subject: [PATCH 1/3] Add a test for #2491

---
 tests/source/impls.rs |  5 +++++
 tests/target/impls.rs | 11 +++++++++++
 2 files changed, 16 insertions(+)

diff --git a/tests/source/impls.rs b/tests/source/impls.rs
index ca8e486646a..85e0ef0d42b 100644
--- a/tests/source/impls.rs
+++ b/tests/source/impls.rs
@@ -152,3 +152,8 @@ impl Foo {
         1
     }
 }
+
+// #2491
+impl<'a, 'b, 'c> SomeThing<Something> for (&'a mut SomethingLong, &'b mut SomethingLong, &'c mut SomethingLong) {
+    fn foo() {}
+}
diff --git a/tests/target/impls.rs b/tests/target/impls.rs
index 91172b39fe5..0bc28acf7ea 100644
--- a/tests/target/impls.rs
+++ b/tests/target/impls.rs
@@ -217,3 +217,14 @@ impl Foo {
         1
     }
 }
+
+// #2491
+impl<'a, 'b, 'c> SomeThing<Something>
+    for (
+        &'a mut SomethingLong,
+        &'b mut SomethingLong,
+        &'c mut SomethingLong,
+    )
+{
+    fn foo() {}
+}

From 71ca21fc23ee0c2ea52d5440dca758bf1344b476 Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Thu, 8 Mar 2018 19:08:38 +0900
Subject: [PATCH 2/3] Disallow combining parens and brackets in impl

---
 src/items.rs | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/items.rs b/src/items.rs
index ce1bc1ae318..3793ae36577 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -33,8 +33,8 @@ use types::join_bounds;
 use utils::{colon_spaces, contains_skip, first_line_width, format_abi, format_constness,
             format_defaultness, format_mutability, format_unsafety, format_visibility,
             is_attributes_extendable, last_line_contains_single_line_comment,
-            last_line_extendable, last_line_used_width, last_line_width, mk_sp,
-            semicolon_for_expr, starts_with_newline, stmt_expr, trimmed_last_line_width};
+            last_line_used_width, last_line_width, mk_sp, semicolon_for_expr, starts_with_newline,
+            stmt_expr, trimmed_last_line_width};
 use vertical::rewrite_with_alignment;
 use visitor::FmtVisitor;
 
@@ -631,8 +631,7 @@ pub fn format_impl(
         }
         result.push_str(&where_clause_str);
 
-        let need_newline = !last_line_extendable(&result)
-            && (last_line_contains_single_line_comment(&result) || result.contains('\n'));
+        let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
         match context.config.brace_style() {
             _ if need_newline => result.push_str(&sep),
             BraceStyle::AlwaysNextLine => result.push_str(&sep),

From 10e37fd42e98dd94a49f696a065b55e9abbda574 Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Thu, 8 Mar 2018 19:08:56 +0900
Subject: [PATCH 3/3] Update tests

---
 tests/target/big-impl-block.rs | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tests/target/big-impl-block.rs b/tests/target/big-impl-block.rs
index bc16f12c9d7..3f26552e802 100644
--- a/tests/target/big-impl-block.rs
+++ b/tests/target/big-impl-block.rs
@@ -52,7 +52,8 @@ impl<ExcessivelyLongGenericName, ExcessivelyLongGenericName, AnotherExcessivelyL
         ExcessivelyLongGenericName,
         ExcessivelyLongGenericName,
         AnotherExcessivelyLongGenericName,
-    > {
+    >
+{
     fn foo() {}
 }
 impl Foo<ExcessivelyLongGenericName, ExcessivelyLongGenericName, AnotherExcessivelyLongGenericName>
@@ -60,7 +61,8 @@ impl Foo<ExcessivelyLongGenericName, ExcessivelyLongGenericName, AnotherExcessiv
         ExcessivelyLongGenericName,
         ExcessivelyLongGenericName,
         AnotherExcessivelyLongGenericName,
-    > {
+    >
+{
     fn foo() {}
 }
 impl<
@@ -72,7 +74,8 @@ impl<
         ExcessivelyLongGenericName,
         ExcessivelyLongGenericName,
         AnotherExcessivelyLongGenericName,
-    > {
+    >
+{
     fn foo() {}
 }