Fix wrap_match_arms resulting in a missing comma (#1307)

* Fix match arms missing comma with "wrap_match_arms = false"

* remove assert; use body_suffix for comma

* basic test case for issue 1127

src/expr.rs

@@ -1293,21 +1293,33 @@ impl Rewrite for ast::Arm {
                 ("{", "}")
             }
         } else {
-            ("", "")
+            ("", ",")
         };
 
+
         let block_sep = match context.config.control_brace_style {
             ControlBraceStyle::AlwaysNextLine => alt_block_sep + body_prefix + "\n",
             _ => String::from(" ") + body_prefix + "\n",
         };
-        Some(format!("{}{} =>{}{}{}\n{}{}",
-                     attr_str.trim_left(),
-                     pats_str,
-                     block_sep,
-                     indent_str,
-                     next_line_body,
-                     shape.indent.to_string(context.config),
-                     body_suffix))
+
+        if context.config.wrap_match_arms {
+            Some(format!("{}{} =>{}{}{}\n{}{}",
+                         attr_str.trim_left(),
+                         pats_str,
+                         block_sep,
+                         indent_str,
+                         next_line_body,
+                         shape.indent.to_string(context.config),
+                         body_suffix))
+        } else {
+            Some(format!("{}{} =>{}{}{}{}",
+                         attr_str.trim_left(),
+                         pats_str,
+                         block_sep,
+                         indent_str,
+                         next_line_body,
+                         body_suffix))
+        }
     }
 }
 

tests/source/issue-1127.rs

@@ -0,0 +1,23 @@
+// rustfmt-max_width:120
+// rustfmt-wrap_match_arms: false
+// rustfmt-match_block_trailing_comma: true
+
+fn a_very_very_very_very_very_very_very_very_very_very_very_long_function_name() -> i32 {
+    42
+}
+
+enum TestEnum {
+    AVeryVeryLongEnumName,
+    AnotherVeryLongEnumName,
+    TheLastVeryLongEnumName,
+}
+
+fn main() {
+    let var = TestEnum::AVeryVeryLongEnumName;
+    let num = match var {
+        TestEnum::AVeryVeryLongEnumName => a_very_very_very_very_very_very_very_very_very_very_very_long_function_name(),
+        TestEnum::AnotherVeryLongEnumName => a_very_very_very_very_very_very_very_very_very_very_very_long_function_name(),
+        TestEnum::TheLastVeryLongEnumName => a_very_very_very_very_very_very_very_very_very_very_very_long_function_name(),
+    };
+}
+

tests/target/issue-1127.rs

@@ -0,0 +1,25 @@
+// rustfmt-max_width:120
+// rustfmt-wrap_match_arms: false
+// rustfmt-match_block_trailing_comma: true
+
+fn a_very_very_very_very_very_very_very_very_very_very_very_long_function_name() -> i32 {
+    42
+}
+
+enum TestEnum {
+    AVeryVeryLongEnumName,
+    AnotherVeryLongEnumName,
+    TheLastVeryLongEnumName,
+}
+
+fn main() {
+    let var = TestEnum::AVeryVeryLongEnumName;
+    let num = match var {
+        TestEnum::AVeryVeryLongEnumName => 
+            a_very_very_very_very_very_very_very_very_very_very_very_long_function_name(),
+        TestEnum::AnotherVeryLongEnumName => 
+            a_very_very_very_very_very_very_very_very_very_very_very_long_function_name(),
+        TestEnum::TheLastVeryLongEnumName => 
+            a_very_very_very_very_very_very_very_very_very_very_very_long_function_name(),
+    };
+}