compiler/rustc_ast_pretty/src/pprust/state/item.rs

   1 use crate::pp::Breaks::Inconsistent;
   2 use crate::pprust::state::delimited::IterDelimited;
   3 use crate::pprust::state::{AnnNode, PrintState, State, INDENT_UNIT};
   4
   5 use rustc_ast as ast;
   6 use rustc_ast::GenericBound;
   7 use rustc_ast::ModKind;
   8 use rustc_span::symbol::Ident;
   9
  10 fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
  11     format!("{}{}", State::to_string(|s| s.print_visibility(vis)), s)
  12 }
  13
  14 impl<'a> State<'a> {
  15     fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod, attrs: &[ast::Attribute]) {
  16         self.print_inner_attributes(attrs);
  17         for item in &nmod.items {
  18             self.print_foreign_item(item);
  19         }
  20     }
  21
  22     fn print_foreign_item(&mut self, item: &ast::ForeignItem) {
  23         let ast::Item { id, span, ident, ref attrs, ref kind, ref vis, tokens: _ } = *item;
  24         self.ann.pre(self, AnnNode::SubItem(id));
  25         self.hardbreak_if_not_bol();
  26         self.maybe_print_comment(span.lo());
  27         self.print_outer_attributes(attrs);
  28         match kind {
  29             ast::ForeignItemKind::Fn(box ast::Fn { defaultness, sig, generics, body }) => {
  30                 self.print_fn_full(sig, ident, generics, vis, *defaultness, body.as_deref(), attrs);
  31             }
  32             ast::ForeignItemKind::Static(ty, mutbl, body) => {
  33                 let def = ast::Defaultness::Final;
  34                 self.print_item_const(ident, Some(*mutbl), ty, body.as_deref(), vis, def);
  35             }
  36             ast::ForeignItemKind::TyAlias(box ast::TyAlias {
  37                 defaultness,
  38                 generics,
  39                 where_clauses,
  40                 where_predicates_split,
  41                 bounds,
  42                 ty,
  43             }) => {
  44                 self.print_associated_type(
  45                     ident,
  46                     generics,
  47                     *where_clauses,
  48                     *where_predicates_split,
  49                     bounds,
  50                     ty.as_deref(),
  51                     vis,
  52                     *defaultness,
  53                 );
  54             }
  55             ast::ForeignItemKind::MacCall(m) => {
  56                 self.print_mac(m);
  57                 if m.args.need_semicolon() {
  58                     self.word(";");
  59                 }
  60             }
  61         }
  62         self.ann.post(self, AnnNode::SubItem(id))
  63     }
  64
  65     fn print_item_const(
  66         &mut self,
  67         ident: Ident,
  68         mutbl: Option<ast::Mutability>,
  69         ty: &ast::Ty,
  70         body: Option<&ast::Expr>,
  71         vis: &ast::Visibility,
  72         defaultness: ast::Defaultness,
  73     ) {
  74         self.head("");
  75         self.print_visibility(vis);
  76         self.print_defaultness(defaultness);
  77         let leading = match mutbl {
  78             None => "const",
  79             Some(ast::Mutability::Not) => "static",
  80             Some(ast::Mutability::Mut) => "static mut",
  81         };
  82         self.word_space(leading);
  83         self.print_ident(ident);
  84         self.word_space(":");
  85         self.print_type(ty);
  86         if body.is_some() {
  87             self.space();
  88         }
  89         self.end(); // end the head-ibox
  90         if let Some(body) = body {
  91             self.word_space("=");
  92             self.print_expr(body);
  93         }
  94         self.word(";");
  95         self.end(); // end the outer cbox
  96     }
  97
  98     fn print_associated_type(
  99         &mut self,
 100         ident: Ident,
 101         generics: &ast::Generics,
 102         where_clauses: (ast::TyAliasWhereClause, ast::TyAliasWhereClause),
 103         where_predicates_split: usize,
 104         bounds: &ast::GenericBounds,
 105         ty: Option<&ast::Ty>,
 106         vis: &ast::Visibility,
 107         defaultness: ast::Defaultness,
 108     ) {
 109         let (before_predicates, after_predicates) =
 110             generics.where_clause.predicates.split_at(where_predicates_split);
 111         self.head("");
 112         self.print_visibility(vis);
 113         self.print_defaultness(defaultness);
 114         self.word_space("type");
 115         self.print_ident(ident);
 116         self.print_generic_params(&generics.params);
 117         self.print_type_bounds(":", bounds);
 118         self.print_where_clause_parts(where_clauses.0.0, before_predicates);
 119         if let Some(ty) = ty {
 120             self.space();
 121             self.word_space("=");
 122             self.print_type(ty);
 123         }
 124         self.print_where_clause_parts(where_clauses.1.0, after_predicates);
 125         self.word(";");
 126         self.end(); // end inner head-block
 127         self.end(); // end outer head-block
 128     }
 129
 130     /// Pretty-prints an item.
 131     crate fn print_item(&mut self, item: &ast::Item) {
 132         self.hardbreak_if_not_bol();
 133         self.maybe_print_comment(item.span.lo());
 134         self.print_outer_attributes(&item.attrs);
 135         self.ann.pre(self, AnnNode::Item(item));
 136         match item.kind {
 137             ast::ItemKind::ExternCrate(orig_name) => {
 138                 self.head(visibility_qualified(&item.vis, "extern crate"));
 139                 if let Some(orig_name) = orig_name {
 140                     self.print_name(orig_name);
 141                     self.space();
 142                     self.word("as");
 143                     self.space();
 144                 }
 145                 self.print_ident(item.ident);
 146                 self.word(";");
 147                 self.end(); // end inner head-block
 148                 self.end(); // end outer head-block
 149             }
 150             ast::ItemKind::Use(ref tree) => {
 151                 self.print_visibility(&item.vis);
 152                 self.word_nbsp("use");
 153                 self.print_use_tree(tree);
 154                 self.word(";");
 155             }
 156             ast::ItemKind::Static(ref ty, mutbl, ref body) => {
 157                 let def = ast::Defaultness::Final;
 158                 self.print_item_const(item.ident, Some(mutbl), ty, body.as_deref(), &item.vis, def);
 159             }
 160             ast::ItemKind::Const(def, ref ty, ref body) => {
 161                 self.print_item_const(item.ident, None, ty, body.as_deref(), &item.vis, def);
 162             }
 163             ast::ItemKind::Fn(box ast::Fn { defaultness, ref sig, ref generics, ref body }) => {
 164                 let body = body.as_deref();
 165                 self.print_fn_full(
 166                     sig,
 167                     item.ident,
 168                     generics,
 169                     &item.vis,
 170                     defaultness,
 171                     body,
 172                     &item.attrs,
 173                 );
 174             }
 175             ast::ItemKind::Mod(unsafety, ref mod_kind) => {
 176                 self.head(Self::to_string(|s| {
 177                     s.print_visibility(&item.vis);
 178                     s.print_unsafety(unsafety);
 179                     s.word("mod");
 180                 }));
 181                 self.print_ident(item.ident);
 182
 183                 match mod_kind {
 184                     ModKind::Loaded(items, ..) => {
 185                         self.nbsp();
 186                         self.bopen();
 187                         self.print_inner_attributes(&item.attrs);
 188                         for item in items {
 189                             self.print_item(item);
 190                         }
 191                         let empty = item.attrs.is_empty() && items.is_empty();
 192                         self.bclose(item.span, empty);
 193                     }
 194                     ModKind::Unloaded => {
 195                         self.word(";");
 196                         self.end(); // end inner head-block
 197                         self.end(); // end outer head-block
 198                     }
 199                 }
 200             }
 201             ast::ItemKind::ForeignMod(ref nmod) => {
 202                 self.head(Self::to_string(|s| {
 203                     s.print_unsafety(nmod.unsafety);
 204                     s.word("extern");
 205                 }));
 206                 if let Some(abi) = nmod.abi {
 207                     self.print_literal(&abi.as_lit());
 208                     self.nbsp();
 209                 }
 210                 self.bopen();
 211                 self.print_foreign_mod(nmod, &item.attrs);
 212                 let empty = item.attrs.is_empty() && nmod.items.is_empty();
 213                 self.bclose(item.span, empty);
 214             }
 215             ast::ItemKind::GlobalAsm(ref asm) => {
 216                 self.head(visibility_qualified(&item.vis, "global_asm!"));
 217                 self.print_inline_asm(asm);
 218                 self.end();
 219             }
 220             ast::ItemKind::TyAlias(box ast::TyAlias {
 221                 defaultness,
 222                 ref generics,
 223                 where_clauses,
 224                 where_predicates_split,
 225                 ref bounds,
 226                 ref ty,
 227             }) => {
 228                 let ty = ty.as_deref();
 229                 self.print_associated_type(
 230                     item.ident,
 231                     generics,
 232                     where_clauses,
 233                     where_predicates_split,
 234                     bounds,
 235                     ty,
 236                     &item.vis,
 237                     defaultness,
 238                 );
 239             }
 240             ast::ItemKind::Enum(ref enum_definition, ref params) => {
 241                 self.print_enum_def(enum_definition, params, item.ident, item.span, &item.vis);
 242             }
 243             ast::ItemKind::Struct(ref struct_def, ref generics) => {
 244                 self.head(visibility_qualified(&item.vis, "struct"));
 245                 self.print_struct(struct_def, generics, item.ident, item.span, true);
 246             }
 247             ast::ItemKind::Union(ref struct_def, ref generics) => {
 248                 self.head(visibility_qualified(&item.vis, "union"));
 249                 self.print_struct(struct_def, generics, item.ident, item.span, true);
 250             }
 251             ast::ItemKind::Impl(box ast::Impl {
 252                 unsafety,
 253                 polarity,
 254                 defaultness,
 255                 constness,
 256                 ref generics,
 257                 ref of_trait,
 258                 ref self_ty,
 259                 ref items,
 260             }) => {
 261                 self.head("");
 262                 self.print_visibility(&item.vis);
 263                 self.print_defaultness(defaultness);
 264                 self.print_unsafety(unsafety);
 265                 self.word("impl");
 266
 267                 if generics.params.is_empty() {
 268                     self.nbsp();
 269                 } else {
 270                     self.print_generic_params(&generics.params);
 271                     self.space();
 272                 }
 273
 274                 self.print_constness(constness);
 275
 276                 if let ast::ImplPolarity::Negative(_) = polarity {
 277                     self.word("!");
 278                 }
 279
 280                 if let Some(ref t) = *of_trait {
 281                     self.print_trait_ref(t);
 282                     self.space();
 283                     self.word_space("for");
 284                 }
 285
 286                 self.print_type(self_ty);
 287                 self.print_where_clause(&generics.where_clause);
 288
 289                 self.space();
 290                 self.bopen();
 291                 self.print_inner_attributes(&item.attrs);
 292                 for impl_item in items {
 293                     self.print_assoc_item(impl_item);
 294                 }
 295                 let empty = item.attrs.is_empty() && items.is_empty();
 296                 self.bclose(item.span, empty);
 297             }
 298             ast::ItemKind::Trait(box ast::Trait {
 299                 is_auto,
 300                 unsafety,
 301                 ref generics,
 302                 ref bounds,
 303                 ref items,
 304                 ..
 305             }) => {
 306                 self.head("");
 307                 self.print_visibility(&item.vis);
 308                 self.print_unsafety(unsafety);
 309                 self.print_is_auto(is_auto);
 310                 self.word_nbsp("trait");
 311                 self.print_ident(item.ident);
 312                 self.print_generic_params(&generics.params);
 313                 let mut real_bounds = Vec::with_capacity(bounds.len());
 314                 for b in bounds.iter() {
 315                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
 316                         self.space();
 317                         self.word_space("for ?");
 318                         self.print_trait_ref(&ptr.trait_ref);
 319                     } else {
 320                         real_bounds.push(b.clone());
 321                     }
 322                 }
 323                 self.print_type_bounds(":", &real_bounds);
 324                 self.print_where_clause(&generics.where_clause);
 325                 self.word(" ");
 326                 self.bopen();
 327                 self.print_inner_attributes(&item.attrs);
 328                 for trait_item in items {
 329                     self.print_assoc_item(trait_item);
 330                 }
 331                 let empty = item.attrs.is_empty() && items.is_empty();
 332                 self.bclose(item.span, empty);
 333             }
 334             ast::ItemKind::TraitAlias(ref generics, ref bounds) => {
 335                 self.head(visibility_qualified(&item.vis, "trait"));
 336                 self.print_ident(item.ident);
 337                 self.print_generic_params(&generics.params);
 338                 let mut real_bounds = Vec::with_capacity(bounds.len());
 339                 // FIXME(durka) this seems to be some quite outdated syntax
 340                 for b in bounds.iter() {
 341                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
 342                         self.space();
 343                         self.word_space("for ?");
 344                         self.print_trait_ref(&ptr.trait_ref);
 345                     } else {
 346                         real_bounds.push(b.clone());
 347                     }
 348                 }
 349                 self.nbsp();
 350                 self.print_type_bounds("=", &real_bounds);
 351                 self.print_where_clause(&generics.where_clause);
 352                 self.word(";");
 353                 self.end(); // end inner head-block
 354                 self.end(); // end outer head-block
 355             }
 356             ast::ItemKind::MacCall(ref mac) => {
 357                 self.print_mac(mac);
 358                 if mac.args.need_semicolon() {
 359                     self.word(";");
 360                 }
 361             }
 362             ast::ItemKind::MacroDef(ref macro_def) => {
 363                 self.print_mac_def(macro_def, &item.ident, item.span, |state| {
 364                     state.print_visibility(&item.vis)
 365                 });
 366             }
 367         }
 368         self.ann.post(self, AnnNode::Item(item))
 369     }
 370
 371     fn print_enum_def(
 372         &mut self,
 373         enum_definition: &ast::EnumDef,
 374         generics: &ast::Generics,
 375         ident: Ident,
 376         span: rustc_span::Span,
 377         visibility: &ast::Visibility,
 378     ) {
 379         self.head(visibility_qualified(visibility, "enum"));
 380         self.print_ident(ident);
 381         self.print_generic_params(&generics.params);
 382         self.print_where_clause(&generics.where_clause);
 383         self.space();
 384         self.print_variants(&enum_definition.variants, span)
 385     }
 386
 387     fn print_variants(&mut self, variants: &[ast::Variant], span: rustc_span::Span) {
 388         self.bopen();
 389         for v in variants {
 390             self.space_if_not_bol();
 391             self.maybe_print_comment(v.span.lo());
 392             self.print_outer_attributes(&v.attrs);
 393             self.ibox(0);
 394             self.print_variant(v);
 395             self.word(",");
 396             self.end();
 397             self.maybe_print_trailing_comment(v.span, None);
 398         }
 399         let empty = variants.is_empty();
 400         self.bclose(span, empty)
 401     }
 402
 403     crate fn print_visibility(&mut self, vis: &ast::Visibility) {
 404         match vis.kind {
 405             ast::VisibilityKind::Public => self.word_nbsp("pub"),
 406             ast::VisibilityKind::Crate(sugar) => match sugar {
 407                 ast::CrateSugar::PubCrate => self.word_nbsp("pub(crate)"),
 408                 ast::CrateSugar::JustCrate => self.word_nbsp("crate"),
 409             },
 410             ast::VisibilityKind::Restricted { ref path, .. } => {
 411                 let path = Self::to_string(|s| s.print_path(path, false, 0));
 412                 if path == "self" || path == "super" {
 413                     self.word_nbsp(format!("pub({})", path))
 414                 } else {
 415                     self.word_nbsp(format!("pub(in {})", path))
 416                 }
 417             }
 418             ast::VisibilityKind::Inherited => {}
 419         }
 420     }
 421
 422     fn print_defaultness(&mut self, defaultness: ast::Defaultness) {
 423         if let ast::Defaultness::Default(_) = defaultness {
 424             self.word_nbsp("default");
 425         }
 426     }
 427
 428     fn print_record_struct_body(&mut self, fields: &[ast::FieldDef], span: rustc_span::Span) {
 429         self.nbsp();
 430         self.bopen();
 431
 432         let empty = fields.is_empty();
 433         if !empty {
 434             self.hardbreak_if_not_bol();
 435
 436             for field in fields {
 437                 self.hardbreak_if_not_bol();
 438                 self.maybe_print_comment(field.span.lo());
 439                 self.print_outer_attributes(&field.attrs);
 440                 self.print_visibility(&field.vis);
 441                 self.print_ident(field.ident.unwrap());
 442                 self.word_nbsp(":");
 443                 self.print_type(&field.ty);
 444                 self.word(",");
 445             }
 446         }
 447
 448         self.bclose(span, empty);
 449     }
 450
 451     fn print_struct(
 452         &mut self,
 453         struct_def: &ast::VariantData,
 454         generics: &ast::Generics,
 455         ident: Ident,
 456         span: rustc_span::Span,
 457         print_finalizer: bool,
 458     ) {
 459         self.print_ident(ident);
 460         self.print_generic_params(&generics.params);
 461         match struct_def {
 462             ast::VariantData::Tuple(..) | ast::VariantData::Unit(..) => {
 463                 if let ast::VariantData::Tuple(..) = struct_def {
 464                     self.popen();
 465                     self.commasep(Inconsistent, struct_def.fields(), |s, field| {
 466                         s.maybe_print_comment(field.span.lo());
 467                         s.print_outer_attributes(&field.attrs);
 468                         s.print_visibility(&field.vis);
 469                         s.print_type(&field.ty)
 470                     });
 471                     self.pclose();
 472                 }
 473                 self.print_where_clause(&generics.where_clause);
 474                 if print_finalizer {
 475                     self.word(";");
 476                 }
 477                 self.end();
 478                 self.end(); // Close the outer-box.
 479             }
 480             ast::VariantData::Struct(ref fields, ..) => {
 481                 self.print_where_clause(&generics.where_clause);
 482                 self.print_record_struct_body(fields, span);
 483             }
 484         }
 485     }
 486
 487     crate fn print_variant(&mut self, v: &ast::Variant) {
 488         self.head("");
 489         self.print_visibility(&v.vis);
 490         let generics = ast::Generics::default();
 491         self.print_struct(&v.data, &generics, v.ident, v.span, false);
 492         if let Some(ref d) = v.disr_expr {
 493             self.space();
 494             self.word_space("=");
 495             self.print_expr(&d.value)
 496         }
 497     }
 498
 499     fn print_assoc_item(&mut self, item: &ast::AssocItem) {
 500         let ast::Item { id, span, ident, ref attrs, ref kind, ref vis, tokens: _ } = *item;
 501         self.ann.pre(self, AnnNode::SubItem(id));
 502         self.hardbreak_if_not_bol();
 503         self.maybe_print_comment(span.lo());
 504         self.print_outer_attributes(attrs);
 505         match kind {
 506             ast::AssocItemKind::Fn(box ast::Fn { defaultness, sig, generics, body }) => {
 507                 self.print_fn_full(sig, ident, generics, vis, *defaultness, body.as_deref(), attrs);
 508             }
 509             ast::AssocItemKind::Const(def, ty, body) => {
 510                 self.print_item_const(ident, None, ty, body.as_deref(), vis, *def);
 511             }
 512             ast::AssocItemKind::TyAlias(box ast::TyAlias {
 513                 defaultness,
 514                 generics,
 515                 where_clauses,
 516                 where_predicates_split,
 517                 bounds,
 518                 ty,
 519             }) => {
 520                 self.print_associated_type(
 521                     ident,
 522                     generics,
 523                     *where_clauses,
 524                     *where_predicates_split,
 525                     bounds,
 526                     ty.as_deref(),
 527                     vis,
 528                     *defaultness,
 529                 );
 530             }
 531             ast::AssocItemKind::MacCall(m) => {
 532                 self.print_mac(m);
 533                 if m.args.need_semicolon() {
 534                     self.word(";");
 535                 }
 536             }
 537         }
 538         self.ann.post(self, AnnNode::SubItem(id))
 539     }
 540
 541     fn print_fn_full(
 542         &mut self,
 543         sig: &ast::FnSig,
 544         name: Ident,
 545         generics: &ast::Generics,
 546         vis: &ast::Visibility,
 547         defaultness: ast::Defaultness,
 548         body: Option<&ast::Block>,
 549         attrs: &[ast::Attribute],
 550     ) {
 551         if body.is_some() {
 552             self.head("");
 553         }
 554         self.print_visibility(vis);
 555         self.print_defaultness(defaultness);
 556         self.print_fn(&sig.decl, sig.header, Some(name), generics);
 557         if let Some(body) = body {
 558             self.nbsp();
 559             self.print_block_with_attrs(body, attrs);
 560         } else {
 561             self.word(";");
 562         }
 563     }
 564
 565     crate fn print_fn(
 566         &mut self,
 567         decl: &ast::FnDecl,
 568         header: ast::FnHeader,
 569         name: Option<Ident>,
 570         generics: &ast::Generics,
 571     ) {
 572         self.print_fn_header_info(header);
 573         if let Some(name) = name {
 574             self.nbsp();
 575             self.print_ident(name);
 576         }
 577         self.print_generic_params(&generics.params);
 578         self.print_fn_params_and_ret(decl, false);
 579         self.print_where_clause(&generics.where_clause)
 580     }
 581
 582     crate fn print_fn_params_and_ret(&mut self, decl: &ast::FnDecl, is_closure: bool) {
 583         let (open, close) = if is_closure { ("|", "|") } else { ("(", ")") };
 584         self.word(open);
 585         self.commasep(Inconsistent, &decl.inputs, |s, param| s.print_param(param, is_closure));
 586         self.word(close);
 587         self.print_fn_ret_ty(&decl.output)
 588     }
 589
 590     fn print_where_clause(&mut self, where_clause: &ast::WhereClause) {
 591         self.print_where_clause_parts(where_clause.has_where_token, &where_clause.predicates);
 592     }
 593
 594     crate fn print_where_clause_parts(
 595         &mut self,
 596         has_where_token: bool,
 597         predicates: &[ast::WherePredicate],
 598     ) {
 599         if predicates.is_empty() && !has_where_token {
 600             return;
 601         }
 602
 603         self.space();
 604         self.word_space("where");
 605
 606         for (i, predicate) in predicates.iter().enumerate() {
 607             if i != 0 {
 608                 self.word_space(",");
 609             }
 610
 611             self.print_where_predicate(predicate);
 612         }
 613     }
 614
 615     pub fn print_where_predicate(&mut self, predicate: &ast::WherePredicate) {
 616         match predicate {
 617             ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
 618                 bound_generic_params,
 619                 bounded_ty,
 620                 bounds,
 621                 ..
 622             }) => {
 623                 self.print_formal_generic_params(bound_generic_params);
 624                 self.print_type(bounded_ty);
 625                 self.print_type_bounds(":", bounds);
 626             }
 627             ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
 628                 lifetime,
 629                 bounds,
 630                 ..
 631             }) => {
 632                 self.print_lifetime_bounds(*lifetime, bounds);
 633             }
 634             ast::WherePredicate::EqPredicate(ast::WhereEqPredicate { lhs_ty, rhs_ty, .. }) => {
 635                 self.print_type(lhs_ty);
 636                 self.space();
 637                 self.word_space("=");
 638                 self.print_type(rhs_ty);
 639             }
 640         }
 641     }
 642
 643     fn print_use_tree(&mut self, tree: &ast::UseTree) {
 644         match tree.kind {
 645             ast::UseTreeKind::Simple(rename, ..) => {
 646                 self.print_path(&tree.prefix, false, 0);
 647                 if let Some(rename) = rename {
 648                     self.nbsp();
 649                     self.word_nbsp("as");
 650                     self.print_ident(rename);
 651                 }
 652             }
 653             ast::UseTreeKind::Glob => {
 654                 if !tree.prefix.segments.is_empty() {
 655                     self.print_path(&tree.prefix, false, 0);
 656                     self.word("::");
 657                 }
 658                 self.word("*");
 659             }
 660             ast::UseTreeKind::Nested(ref items) => {
 661                 if !tree.prefix.segments.is_empty() {
 662                     self.print_path(&tree.prefix, false, 0);
 663                     self.word("::");
 664                 }
 665                 if items.is_empty() {
 666                     self.word("{}");
 667                 } else if items.len() == 1 {
 668                     self.print_use_tree(&items[0].0);
 669                 } else {
 670                     self.cbox(INDENT_UNIT);
 671                     self.word("{");
 672                     self.zerobreak();
 673                     self.ibox(0);
 674                     for use_tree in items.iter().delimited() {
 675                         self.print_use_tree(&use_tree.0);
 676                         if !use_tree.is_last {
 677                             self.word(",");
 678                             if let ast::UseTreeKind::Nested(_) = use_tree.0.kind {
 679                                 self.hardbreak();
 680                             } else {
 681                                 self.space();
 682                             }
 683                         }
 684                     }
 685                     self.end();
 686                     self.trailing_comma();
 687                     self.offset(-INDENT_UNIT);
 688                     self.word("}");
 689                     self.end();
 690                 }
 691             }
 692         }
 693     }
 694 }