Remove newlines between list elements for expressions

src/expr.rs

@@ -567,6 +567,7 @@ pub fn rewrite_array<'a, I>(
         },
         shape: nested_shape,
         ends_with_newline: ends_with_newline,
+        preserve_newline: false,
         config: context.config,
     };
     let list_str = try_opt!(write_list(&items, &fmt));
@@ -642,6 +643,7 @@ fn rewrite_closure_fn_decl(
         trailing_separator: SeparatorTactic::Never,
         shape: arg_shape,
         ends_with_newline: false,
+        preserve_newline: true,
         config: context.config,
     };
     let list_str = try_opt!(write_list(&item_vec, &fmt));
@@ -1696,6 +1698,7 @@ fn rewrite_match_pattern(
         trailing_separator: SeparatorTactic::Never,
         shape: pat_shape,
         ends_with_newline: false,
+        preserve_newline: false,
         config: context.config,
     };
     let pats_str = try_opt!(write_list(&items, &fmt));
@@ -2188,6 +2191,7 @@ fn rewrite_call_args<'a, T>(
         },
         shape: shape,
         ends_with_newline: context.use_block_indent() && tactic == DefinitiveListTactic::Vertical,
+        preserve_newline: false,
         config: context.config,
     };
 
@@ -2783,6 +2787,7 @@ fn rewrite_tuple_in_visual_indent_style<'a, T>(
         trailing_separator: SeparatorTactic::Never,
         shape: shape,
         ends_with_newline: false,
+        preserve_newline: false,
         config: context.config,
     };
     let list_str = try_opt!(write_list(&item_vec, &fmt));

src/imports.rs

@@ -478,6 +478,7 @@ fn rewrite_use_list(
         },
         shape: nested_shape,
         ends_with_newline: ends_with_newline,
+        preserve_newline: true,
         config: context.config,
     };
     let list_str = try_opt!(write_list(&items[first_index..], &fmt));

src/items.rs

@@ -477,6 +477,7 @@ fn format_variant_list(
             trailing_separator: self.config.trailing_comma(),
             shape: shape,
             ends_with_newline: true,
+            preserve_newline: true,
             config: self.config,
         };
 
@@ -2252,6 +2253,7 @@ enum ArgumentKind<'a> {
         },
         shape: Shape::legacy(budget, indent),
         ends_with_newline: tactic.ends_with_newline(context.config.fn_args_layout()),
+        preserve_newline: true,
         config: context.config,
     };
 
@@ -2425,6 +2427,7 @@ pub fn format_generics_item_list<I>(
         },
         shape: shape,
         ends_with_newline: tactic.ends_with_newline(context.config.generics_indent()),
+        preserve_newline: true,
         config: context.config,
     };
 
@@ -2538,6 +2541,7 @@ fn rewrite_where_clause_rfc_style(
         trailing_separator: comma_tactic,
         shape: clause_shape,
         ends_with_newline: true,
+        preserve_newline: true,
         config: context.config,
     };
     let preds_str = try_opt!(write_list(&items.collect::<Vec<_>>(), &fmt));
@@ -2639,6 +2643,7 @@ fn rewrite_where_clause(
         trailing_separator: comma_tactic,
         shape: Shape::legacy(budget, offset),
         ends_with_newline: tactic.ends_with_newline(context.config.where_pred_indent()),
+        preserve_newline: true,
         config: context.config,
     };
     let preds_str = try_opt!(write_list(&item_vec, &fmt));

src/lists.rs

@@ -65,6 +65,8 @@ pub struct ListFormatting<'a> {
     // Non-expressions, e.g. items, will have a new line at the end of the list.
     // Important for comment styles.
     pub ends_with_newline: bool,
+    // Remove newlines between list elements for expressions.
+    pub preserve_newline: bool,
     pub config: &'a Config,
 }
 
@@ -342,7 +344,9 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
             item_max_width = None;
         }
 
-        if !last && tactic == DefinitiveListTactic::Vertical && item.new_lines {
+        if formatting.preserve_newline && !last && tactic == DefinitiveListTactic::Vertical &&
+            item.new_lines
+        {
             item_max_width = None;
             result.push('\n');
         }
@@ -675,6 +679,7 @@ pub fn struct_lit_formatting<'a>(
         },
         shape: shape,
         ends_with_newline: ends_with_newline,
+        preserve_newline: true,
         config: context.config,
     }
 }

src/types.rs

@@ -361,6 +361,7 @@ enum ArgumentKind<T>
         },
         shape: list_shape,
         ends_with_newline: tactic.ends_with_newline(context.config.fn_call_style()),
+        preserve_newline: true,
         config: context.config,
     };
 

src/vertical.rs

@@ -229,6 +229,7 @@ fn rewrite_aligned_items_inner<T: AlignedItem>(
         trailing_separator: context.config.trailing_comma(),
         shape: item_shape,
         ends_with_newline: true,
+        preserve_newline: true,
         config: context.config,
     };
     write_list(&items, &fmt)

src/visitor.rs

@@ -820,6 +820,7 @@ fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
                     trailing_separator: SeparatorTactic::Never,
                     shape: item_shape,
                     ends_with_newline: false,
+                    preserve_newline: false,
                     config: context.config,
                 };
                 format!("{}({})", name, try_opt!(write_list(&item_vec, &fmt)))