Add flag to the ListFormatting struct for nested imports

src/attr.rs

@@ -247,6 +247,7 @@ fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
                     shape: item_shape,
                     ends_with_newline: false,
                     preserve_newline: false,
+                    nested: false,
                     config: context.config,
                 };
                 let item_str = write_list(&item_vec, &fmt)?;

src/closures.rs

@@ -260,6 +260,7 @@ fn rewrite_closure_fn_decl(
         shape: arg_shape,
         ends_with_newline: false,
         preserve_newline: true,
+        nested: false,
         config: context.config,
     };
     let list_str = write_list(&item_vec, &fmt)?;

src/expr.rs

@@ -1338,6 +1338,7 @@ pub fn rewrite_multiple_patterns(
         shape,
         ends_with_newline: false,
         preserve_newline: false,
+        nested: false,
         config: context.config,
     };
     write_list(&items, &fmt)
@@ -1902,6 +1903,7 @@ fn rewrite_tuple_in_visual_indent_style<'a, T>(
         shape,
         ends_with_newline: false,
         preserve_newline: false,
+        nested: false,
         config: context.config,
     };
     let list_str = write_list(&item_vec, &fmt)?;

src/imports.rs

@@ -727,6 +727,7 @@ fn rewrite_nested_use_tree(
         shape: nested_shape,
         ends_with_newline,
         preserve_newline: true,
+        nested: has_nested_list,
         config: context.config,
     };
 

src/items.rs

@@ -533,6 +533,7 @@ fn format_variant_list(
             shape,
             ends_with_newline: true,
             preserve_newline: true,
+            nested: false,
             config: self.config,
         };
 
@@ -2307,6 +2308,7 @@ enum ArgumentKind<'a> {
         shape: Shape::legacy(budget, indent),
         ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
         preserve_newline: true,
+        nested: false,
         config: context.config,
     };
 
@@ -2494,6 +2496,7 @@ fn rewrite_where_clause_rfc_style(
         shape: clause_shape,
         ends_with_newline: true,
         preserve_newline: true,
+        nested: false,
         config: context.config,
     };
     let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
@@ -2607,6 +2610,7 @@ fn rewrite_where_clause(
         shape: Shape::legacy(budget, offset),
         ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
         preserve_newline: true,
+        nested: false,
         config: context.config,
     };
     let preds_str = write_list(&item_vec, &fmt)?;

src/lists.rs

@@ -34,6 +34,8 @@ pub struct ListFormatting<'a> {
     pub ends_with_newline: bool,
     // Remove newlines between list elements for expressions.
     pub preserve_newline: bool,
+    // Nested import lists get some special handling for the "Mixed" list type
+    pub nested: bool,
     pub config: &'a Config,
 }
 
@@ -288,7 +290,8 @@ pub fn write_list<I, T>(items: I, formatting: &ListFormatting) -> Option<String>
                 // 1 is space between separator and item.
                 if (line_len > 0 && line_len + 1 + total_width > formatting.shape.width)
                     || prev_item_had_post_comment
-                    || (prev_item_is_nested_import || (!first && inner_item.contains("::")))
+                    || (formatting.nested
+                        && (prev_item_is_nested_import || (!first && inner_item.contains("::"))))
                 {
                     result.push('\n');
                     result.push_str(indent_str);
@@ -824,6 +827,7 @@ pub fn struct_lit_formatting<'a>(
         shape,
         ends_with_newline,
         preserve_newline: true,
+        nested: false,
         config: context.config,
     }
 }

src/macros.rs

@@ -399,6 +399,7 @@ pub fn rewrite_macro_def(
         shape: arm_shape,
         ends_with_newline: true,
         preserve_newline: true,
+        nested: false,
         config: context.config,
     };
 

src/matches.rs

@@ -224,6 +224,7 @@ fn rewrite_match_arms(
         shape: arm_shape,
         ends_with_newline: true,
         preserve_newline: true,
+        nested: false,
         config: context.config,
     };
 

src/overflow.rs

@@ -388,6 +388,7 @@ fn rewrite_items(&self) -> Option<(bool, String)> {
                 _ => false,
             },
             preserve_newline: false,
+            nested: false,
             config: self.context.config,
         };
 

src/reorder.rs

@@ -77,6 +77,7 @@ fn wrap_reorderable_items(
         shape,
         ends_with_newline: true,
         preserve_newline: false,
+        nested: false,
         config: context.config,
     };
 

src/types.rs

@@ -366,6 +366,7 @@ enum ArgumentKind<T>
         shape: list_shape,
         ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
         preserve_newline: true,
+        nested: false,
         config: context.config,
     };
 

src/vertical.rs

@@ -252,6 +252,7 @@ fn rewrite_aligned_items_inner<T: AlignedItem>(
         shape: item_shape,
         ends_with_newline: true,
         preserve_newline: true,
+        nested: false,
         config: context.config,
     };
     write_list(&items, &fmt)