From 96a2f25788ebda721bdd52de9e6c178ed364a5aa Mon Sep 17 00:00:00 2001
From: Nick Cameron <ncameron@mozilla.com>
Date: Mon, 14 Mar 2016 18:55:55 +1300
Subject: [PATCH] Keep empty extern blocks on one line

Closes #462
---
 src/items.rs           | 23 ++++++++++++++---------
 tests/source/extern.rs |  4 ++++
 tests/target/extern.rs |  2 ++
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/items.rs b/src/items.rs
index 1c5eaa2a631..d70f780df5a 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -84,19 +84,24 @@ impl<'a> FmtVisitor<'a> {
         self.buffer.push_str(&::utils::format_abi(fm.abi));
 
         let snippet = self.snippet(span);
-        let brace_pos = snippet.find_uncommented("{").unwrap() as u32;
+        let brace_pos = snippet.find_uncommented("{").unwrap();
 
-        // FIXME: this skips comments between the extern keyword and the opening
-        // brace.
-        self.last_pos = span.lo + BytePos(brace_pos);
-        self.block_indent = self.block_indent.block_indent(self.config);
+        if fm.items.is_empty() && !contains_comment(&snippet[brace_pos..]) {
+            self.buffer.push_str("{");
+        } else {
+            // FIXME: this skips comments between the extern keyword and the opening
+            // brace.
+            self.last_pos = span.lo + BytePos(brace_pos as u32);
+            self.block_indent = self.block_indent.block_indent(self.config);
 
-        for item in &fm.items {
-            self.format_foreign_item(&*item);
+            for item in &fm.items {
+                self.format_foreign_item(&*item);
+            }
+
+            self.block_indent = self.block_indent.block_unindent(self.config);
+            self.format_missing_with_indent(span.hi - BytePos(1));
         }
 
-        self.block_indent = self.block_indent.block_unindent(self.config);
-        self.format_missing_with_indent(span.hi - BytePos(1));
         self.buffer.push_str("}");
         self.last_pos = span.hi;
     }
diff --git a/tests/source/extern.rs b/tests/source/extern.rs
index e33b646b726..347612dd8f1 100644
--- a/tests/source/extern.rs
+++ b/tests/source/extern.rs
@@ -34,3 +34,7 @@ libc::c_long;
                                file: *mut FILE)
                               -> *mut FILE;
    }
+
+extern {
+
+}
diff --git a/tests/target/extern.rs b/tests/target/extern.rs
index ca8c43d8b2c..e25e8b01cd4 100644
--- a/tests/target/extern.rs
+++ b/tests/target/extern.rs
@@ -45,3 +45,5 @@ extern "C" {
                    file: *mut FILE)
                    -> *mut FILE;
 }
+
+extern "C" {}