Add leave_last field to ListItems

src/expr.rs

@@ -466,6 +466,7 @@ where
         |item| item.rewrite(context, nested_shape),
         span.lo,
         span.hi,
+        false,
     ).collect::<Vec<_>>();
 
     if items.is_empty() {
@@ -587,6 +588,7 @@ fn rewrite_closure_fn_decl(
         |arg| arg.rewrite(context, arg_shape),
         context.codemap.span_after(span, "|"),
         body.span.lo,
+        false,
     );
     let item_vec = arg_items.collect::<Vec<_>>();
     // 1 = space between arguments and return type.
@@ -2190,6 +2192,7 @@ where
         |item| item.rewrite(context, shape),
         span.lo,
         span.hi,
+        true,
     );
     let mut item_vec: Vec<_> = items.collect();
 
@@ -2651,6 +2654,7 @@ fn rewrite_struct_lit<'a>(
             rewrite,
             body_lo,
             span.hi,
+            false,
         );
         let item_vec = items.collect::<Vec<_>>();
 
@@ -2803,6 +2807,7 @@ where
         |item| item.rewrite(context, nested_shape),
         list_lo,
         span.hi - BytePos(1),
+        false,
     );
     let item_vec: Vec<_> = items.collect();
     let tactic = definitive_tactic(

src/imports.rs

@@ -442,6 +442,7 @@ fn rewrite_use_list(
             rewrite_path_item,
             context.codemap.span_after(span, "{"),
             span.hi,
+            false,
         );
         items.extend(iter);
         items

src/items.rs

@@ -469,6 +469,7 @@ impl<'a> FmtVisitor<'a> {
             |f| self.format_variant(f),
             body_lo,
             body_hi,
+            false,
         );
 
         let shape = Shape::indented(self.block_indent, self.config)
@@ -2207,6 +2208,7 @@ fn rewrite_args(
             },
             comment_span_start,
             span.hi,
+            false,
         );
 
         arg_items.extend(more_items);
@@ -2411,6 +2413,7 @@ fn rewrite_generics_inner(
         |&(_, ref str)| str.clone(),
         context.codemap.span_after(span, "<"),
         span.hi,
+        false,
     );
     format_generics_item_list(context, items, shape, one_line_width)
 }
@@ -2554,6 +2557,7 @@ fn rewrite_where_clause_rfc_style(
         |pred| pred.rewrite(context, block_shape),
         span_start,
         span_end,
+        false,
     );
     let comma_tactic = if where_clause_option.suppress_comma {
         SeparatorTactic::Never
@@ -2654,6 +2658,7 @@ fn rewrite_where_clause(
         |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
         span_start,
         span_end,
+        false,
     );
     let item_vec = items.collect::<Vec<_>>();
     // FIXME: we don't need to collect here if the where_layout isn't

src/lists.rs

@@ -454,6 +454,7 @@ where
     prev_span_end: BytePos,
     next_span_start: BytePos,
     terminator: &'a str,
+    leave_last: bool,
 }
 
 impl<'a, T, I, F1, F2, F3> Iterator for ListItems<'a, I, F1, F2, F3>
@@ -592,7 +593,11 @@ where
             ListItem {
                 pre_comment: pre_comment,
                 pre_comment_style: pre_comment_style,
-                item: (self.get_item_string)(&item),
+                item: if self.inner.peek().is_none() && self.leave_last {
+                    None
+                } else {
+                    (self.get_item_string)(&item)
+                },
                 post_comment: post_comment,
                 new_lines: new_lines,
             }
@@ -610,6 +615,7 @@ pub fn itemize_list<'a, T, I, F1, F2, F3>(
     get_item_string: F3,
     prev_span_end: BytePos,
     next_span_start: BytePos,
+    leave_last: bool,
 ) -> ListItems<'a, I, F1, F2, F3>
 where
     I: Iterator<Item = T>,
@@ -626,6 +632,7 @@ where
         prev_span_end: prev_span_end,
         next_span_start: next_span_start,
         terminator: terminator,
+        leave_last: leave_last,
     }
 }
 

src/patterns.rs

@@ -162,6 +162,7 @@ fn rewrite_struct_pat(
         |f| f.node.rewrite(context, v_shape),
         context.codemap.span_after(span, "{"),
         span.hi,
+        false,
     );
     let item_vec = items.collect::<Vec<_>>();
 
@@ -342,6 +343,7 @@ fn count_wildcard_suffix_len(
         |item| item.rewrite(context, shape),
         context.codemap.span_after(span, "("),
         span.hi - BytePos(1),
+        false,
     ).collect();
 
     for item in items.iter().rev().take_while(|i| match i.item {

src/types.rs

@@ -241,6 +241,7 @@ fn rewrite_segment(
                     |seg| seg.rewrite(context, generics_shape),
                     list_lo,
                     span_hi,
+                    false,
                 );
                 let generics_str = try_opt!(format_generics_item_list(
                     context,
@@ -344,6 +345,7 @@ where
         },
         list_lo,
         span.hi,
+        false,
     );
 
     let item_vec: Vec<_> = items.collect();

src/vertical.rs

@@ -219,6 +219,7 @@ fn rewrite_aligned_items_inner<T: AlignedItem>(
         |field| field.rewrite_aligned_item(context, item_shape, field_prefix_max_width),
         span.lo,
         span.hi,
+        false,
     ).collect::<Vec<_>>();
 
     let tactic = definitive_tactic(

src/visitor.rs

@@ -818,6 +818,7 @@ impl Rewrite for ast::MetaItem {
                     |nested_meta_item| nested_meta_item.rewrite(context, item_shape),
                     self.span.lo,
                     hi,
+                    false,
                 );
                 let item_vec = items.collect::<Vec<_>>();
                 let fmt = ListFormatting {