Catch attributes before comments

Closes #1280
Closes #1284

Cargo.lock

@@ -1,6 +1,6 @@
 [root]
 name = "rustfmt"
-version = "0.7.0"
+version = "0.7.1"
 dependencies = [
  "diff 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "env_logger 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",

src/missed_spans.rs

@@ -84,6 +84,8 @@ impl<'a> FmtVisitor<'a> {
         let big_diff = (span.lo - big_span_lo).to_usize();
         let snippet = self.snippet(span);
 
+        debug!("write_snippet `{}`", snippet);
+
         self.write_snippet_inner(big_snippet, big_diff, &snippet, process_last_snippet);
     }
 
@@ -114,6 +116,8 @@ impl<'a> FmtVisitor<'a> {
         let snippet = &*replaced;
 
         for (kind, offset, subslice) in CommentCodeSlices::new(snippet) {
+            debug!("{:?}: {:?}", kind, subslice);
+
             if let CodeCharKind::Comment = kind {
                 let last_char = big_snippet[..(offset + big_diff)]
                     .chars()
@@ -199,6 +203,13 @@ impl<'a> FmtVisitor<'a> {
                     last_wspace = None;
                 }
             }
+
+            let remaining = snippet[line_start..subslice.len() + offset].trim();
+            if !remaining.is_empty() {
+                self.buffer.push_str(remaining);
+                line_start = subslice.len() + offset;
+                rewrite_next_comment = rewrite_next_comment || kind == CodeCharKind::Normal;
+            }
         }
 
         process_last_snippet(self, &snippet[line_start..], snippet);

tests/source/comment4.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)] // bar
+
 //! Doc comment
 fn test() {
 // comment
@@ -44,3 +46,8 @@ fn debug_function() {
     println!("hello");
 }
 // */
+
+#[link_section=".vectors"]
+#[no_mangle] // Test this attribute is preserved.
+#[cfg_attr(rustfmt, rustfmt_skip)]
+pub static ISSUE_1284: [i32; 16] = [];

tests/target/comment4.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)] // bar
+
 //! Doc comment
 fn test() {
     // comment
@@ -43,3 +45,8 @@ fn debug_function() {
     println!("hello");
 }
 // */
+
+#[link_section=".vectors"]
+#[no_mangle] // Test this attribute is preserved.
+#[cfg_attr(rustfmt, rustfmt_skip)]
+pub static ISSUE_1284: [i32; 16] = [];

tests/target/fn.rs

@@ -86,7 +86,7 @@ fn ______________________baz(a: i32)
         *mut ::std::option::Option<extern "C" fn(arg1: i32,
                                                 _____________________a: i32,
                                                 arg3: i32)
-                                    -> ()> {
+-> ()>{
 }
 
 pub fn check_path<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,