Don't drop opening brace on long line matches. (#1228)

* Don't drop opening brace on long line matches.

Fixes #1225

* Added a test case for long match arms with braces on newline.

Author: luke-clifton

src/expr.rs

@@ -1315,17 +1315,17 @@ impl Rewrite for ast::Arm {
         let indent_str = offset.block_indent(context.config).to_string(context.config);
         let (body_prefix, body_suffix) = if context.config.wrap_match_arms {
             if context.config.match_block_trailing_comma {
-                (" {", "},")
+                ("{", "},")
             } else {
-                (" {", "}")
+                ("{", "}")
             }
         } else {
             ("", "")
         };
 
         let block_sep = match context.config.control_brace_style {
-            ControlBraceStyle::AlwaysNextLine => alt_block_sep,
-            ControlBraceStyle::AlwaysSameLine => String::from(body_prefix) + "\n",
+            ControlBraceStyle::AlwaysNextLine => alt_block_sep + body_prefix + "\n",
+            ControlBraceStyle::AlwaysSameLine => String::from(" ") + body_prefix + "\n",
         };
         Some(format!("{}{} =>{}{}{}\n{}{}",
                      attr_str.trim_left(),

tests/source/long-match-arms-brace-newline.rs

@@ -0,0 +1,14 @@
+// rustfmt-max_width: 80
+// rustfmt-control_brace_style: AlwaysNextLine
+
+fn main() {
+    match x {
+        aaaaaaaa::Bbbbb::Ccccccccccccc(_, Some(ref x)) if x ==
+            "aaaaaaaaaaa \
+            aaaaaaa \
+            aaaaaa" => {
+            Ok(())
+        }
+            _ => Err(x),
+    }
+}

tests/target/long-match-arms-brace-newline.rs

@@ -0,0 +1,15 @@
+// rustfmt-max_width: 80
+// rustfmt-control_brace_style: AlwaysNextLine
+
+fn main() {
+    match x
+    {
+        aaaaaaaa::Bbbbb::Ccccccccccccc(_, Some(ref x)) if x ==
+                                                          "aaaaaaaaaaa \
+                                                           aaaaaaa aaaaaa" =>
+        {
+            Ok(())
+        }
+        _ => Err(x),
+    }
+}