Comments on their own lines between args

src/functions.rs

@@ -236,10 +236,11 @@ impl<'a> FmtVisitor<'a> {
             let cur_start = get_lo(&item);
             let snippet = self.snippet(codemap::mk_sp(prev_end, cur_start));
             let mut snippet = snippet.trim();
+            let white_space: &[_] = &[' ', '\t'];
             if snippet.starts_with(separator) {
-                snippet = snippet[1..].trim();
+                snippet = snippet[separator.len()..].trim_matches(white_space);
             } else if snippet.ends_with(separator) {
-                snippet = snippet[..snippet.len()-1].trim();
+                snippet = snippet[..snippet.len()-separator.len()].trim_matches(white_space);
             }
             result.push(snippet.to_string());
             prev_end = get_hi(&item);

src/lists.rs

@@ -124,7 +124,9 @@ pub fn write_list<'b>(items: &[(String, String)], formatting: &ListFormatting<'b
         result.push_str(item);
 
         if tactic != ListTactic::Vertical && comment.len() > 0 {
-            result.push(' ');
+            if !comment.starts_with('\n') {
+                result.push(' ');
+            }
             result.push_str(comment);
         }
 
@@ -133,7 +135,9 @@ pub fn write_list<'b>(items: &[(String, String)], formatting: &ListFormatting<'b
         }
 
         if tactic == ListTactic::Vertical && comment.len() > 0 {
-            result.push(' ');
+            if !comment.starts_with('\n') {
+                result.push(' ');
+            }
             result.push_str(comment);
         }
     }

tests/idem/comments-fn.rs

@@ -4,7 +4,10 @@
 fn foo<F, G>(a: aaaaaaaaaaaaa, // A comment
              b: bbbbbbbbbbbbb, /* a second comment */
              c: ccccccccccccc,
+             // Newline comment
              d: ddddddddddddd,
+             //  A multi line comment
+             // between args.
              e: eeeeeeeeeeeee /* comment before paren*/)
     -> bar
     where F: Foo, // COmment after where clause