src/librustc/hir/print.rs

   1 use rustc_target::spec::abi::Abi;
   2 use syntax::ast;
   3 use syntax::source_map::{SourceMap, Spanned};
   4 use syntax::parse::ParseSess;
   5 use syntax::print::pp::{self, Breaks};
   6 use syntax::print::pp::Breaks::{Consistent, Inconsistent};
   7 use syntax::print::pprust::{self, Comments, PrintState};
   8 use syntax::symbol::kw;
   9 use syntax::util::parser::{self, AssocOp, Fixity};
  10 use syntax_pos::{self, BytePos, FileName};
  11
  12 use crate::hir;
  13 use crate::hir::{PatKind, GenericBound, TraitBoundModifier, RangeEnd};
  14 use crate::hir::{GenericParam, GenericParamKind, GenericArg};
  15 use crate::hir::ptr::P;
  16
  17 use std::borrow::Cow;
  18 use std::cell::Cell;
  19 use std::vec;
  20
  21 pub enum AnnNode<'a> {
  22     Name(&'a ast::Name),
  23     Block(&'a hir::Block),
  24     Item(&'a hir::Item),
  25     SubItem(hir::HirId),
  26     Expr(&'a hir::Expr),
  27     Pat(&'a hir::Pat),
  28     Arm(&'a hir::Arm),
  29 }
  30
  31 pub enum Nested {
  32     Item(hir::ItemId),
  33     TraitItem(hir::TraitItemId),
  34     ImplItem(hir::ImplItemId),
  35     Body(hir::BodyId),
  36     BodyParamPat(hir::BodyId, usize)
  37 }
  38
  39 pub trait PpAnn {
  40     fn nested(&self, _state: &mut State<'_>, _nested: Nested) {
  41     }
  42     fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {
  43     }
  44     fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {
  45     }
  46     fn try_fetch_item(&self, _: hir::HirId) -> Option<&hir::Item> {
  47         None
  48     }
  49 }
  50
  51 pub struct NoAnn;
  52 impl PpAnn for NoAnn {}
  53 pub const NO_ANN: &dyn PpAnn = &NoAnn;
  54
  55 impl PpAnn for hir::Crate {
  56     fn try_fetch_item(&self, item: hir::HirId) -> Option<&hir::Item> {
  57         Some(self.item(item))
  58     }
  59     fn nested(&self, state: &mut State<'_>, nested: Nested) {
  60         match nested {
  61             Nested::Item(id) => state.print_item(self.item(id.id)),
  62             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
  63             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
  64             Nested::Body(id) => state.print_expr(&self.body(id).value),
  65             Nested::BodyParamPat(id, i) => state.print_pat(&self.body(id).params[i].pat)
  66         }
  67     }
  68 }
  69
  70 pub struct State<'a> {
  71     pub s: pp::Printer,
  72     comments: Option<Comments<'a>>,
  73     ann: &'a (dyn PpAnn + 'a),
  74 }
  75
  76 impl std::ops::Deref for State<'_> {
  77     type Target = pp::Printer;
  78     fn deref(&self) -> &Self::Target {
  79         &self.s
  80     }
  81 }
  82
  83 impl std::ops::DerefMut for State<'_> {
  84     fn deref_mut(&mut self) -> &mut Self::Target {
  85         &mut self.s
  86     }
  87 }
  88
  89 impl<'a> PrintState<'a> for State<'a> {
  90     fn comments(&mut self) -> &mut Option<Comments<'a>> {
  91         &mut self.comments
  92     }
  93
  94     fn print_ident(&mut self, ident: ast::Ident) {
  95         self.s.word(pprust::ast_ident_to_string(ident, ident.is_raw_guess()));
  96         self.ann.post(self, AnnNode::Name(&ident.name))
  97     }
  98
  99     fn print_generic_args(&mut self, args: &ast::GenericArgs, _colons_before_params: bool) {
 100         span_bug!(args.span(), "AST generic args printed by HIR pretty-printer");
 101     }
 102 }
 103
 104 pub const INDENT_UNIT: usize = 4;
 105
 106 /// Requires you to pass an input filename and reader so that
 107 /// it can scan the input text for comments to copy forward.
 108 pub fn print_crate<'a>(cm: &'a SourceMap,
 109                        sess: &ParseSess,
 110                        krate: &hir::Crate,
 111                        filename: FileName,
 112                        input: String,
 113                        ann: &'a dyn PpAnn) -> String {
 114     let mut s = State::new_from_input(cm, sess, filename, input, ann);
 115
 116     // When printing the AST, we sometimes need to inject `#[no_std]` here.
 117     // Since you can't compile the HIR, it's not necessary.
 118
 119     s.print_mod(&krate.module, &krate.attrs);
 120     s.print_remaining_comments();
 121     s.s.eof()
 122 }
 123
 124 impl<'a> State<'a> {
 125     pub fn new_from_input(cm: &'a SourceMap,
 126                           sess: &ParseSess,
 127                           filename: FileName,
 128                           input: String,
 129                           ann: &'a dyn PpAnn)
 130                           -> State<'a> {
 131         State {
 132             s: pp::mk_printer(),
 133             comments: Some(Comments::new(cm, sess, filename, input)),
 134             ann,
 135         }
 136     }
 137 }
 138
 139 pub fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
 140     where F: FnOnce(&mut State<'_>)
 141 {
 142     let mut printer = State {
 143         s: pp::mk_printer(),
 144         comments: None,
 145         ann,
 146     };
 147     f(&mut printer);
 148     printer.s.eof()
 149 }
 150
 151 pub fn visibility_qualified<S: Into<Cow<'static, str>>>(vis: &hir::Visibility, w: S) -> String {
 152     to_string(NO_ANN, |s| {
 153         s.print_visibility(vis);
 154         s.s.word(w)
 155     })
 156 }
 157
 158 impl<'a> State<'a> {
 159     pub fn cbox(&mut self, u: usize) {
 160         self.s.cbox(u);
 161     }
 162
 163     pub fn nbsp(&mut self) {
 164         self.s.word(" ")
 165     }
 166
 167     pub fn word_nbsp<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 168         self.s.word(w);
 169         self.nbsp()
 170     }
 171
 172     pub fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 173         let w = w.into();
 174         // outer-box is consistent
 175         self.cbox(INDENT_UNIT);
 176         // head-box is inconsistent
 177         self.ibox(w.len() + 1);
 178         // keyword that starts the head
 179         if !w.is_empty() {
 180             self.word_nbsp(w);
 181         }
 182     }
 183
 184     pub fn bopen(&mut self) {
 185         self.s.word("{");
 186         self.end(); // close the head-box
 187     }
 188
 189     pub fn bclose_maybe_open(&mut self,
 190                              span: syntax_pos::Span,
 191                              close_box: bool)
 192                              {
 193         self.maybe_print_comment(span.hi());
 194         self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
 195         self.s.word("}");
 196         if close_box {
 197             self.end(); // close the outer-box
 198         }
 199     }
 200
 201     pub fn bclose(&mut self, span: syntax_pos::Span) {
 202         self.bclose_maybe_open(span, true)
 203     }
 204
 205     pub fn space_if_not_bol(&mut self) {
 206         if !self.s.is_beginning_of_line() {
 207             self.s.space();
 208         }
 209     }
 210
 211     pub fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
 212         if !self.s.is_beginning_of_line() {
 213             self.s.break_offset(n, off)
 214         } else {
 215             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 216                 // We do something pretty sketchy here: tuck the nonzero
 217                 // offset-adjustment we were going to deposit along with the
 218                 // break into the previous hardbreak.
 219                 self.s.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 220             }
 221         }
 222     }
 223
 224     // Synthesizes a comment that was not textually present in the original source
 225     // file.
 226     pub fn synth_comment(&mut self, text: String) {
 227         self.s.word("/*");
 228         self.s.space();
 229         self.s.word(text);
 230         self.s.space();
 231         self.s.word("*/")
 232     }
 233
 234     pub fn commasep_cmnt<T, F, G>(&mut self,
 235                                   b: Breaks,
 236                                   elts: &[T],
 237                                   mut op: F,
 238                                   mut get_span: G)
 239         where F: FnMut(&mut State<'_>, &T),
 240               G: FnMut(&T) -> syntax_pos::Span
 241     {
 242         self.rbox(0, b);
 243         let len = elts.len();
 244         let mut i = 0;
 245         for elt in elts {
 246             self.maybe_print_comment(get_span(elt).hi());
 247             op(self, elt);
 248             i += 1;
 249             if i < len {
 250                 self.s.word(",");
 251                 self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()));
 252                 self.space_if_not_bol();
 253             }
 254         }
 255         self.end();
 256     }
 257
 258     pub fn commasep_exprs(&mut self, b: Breaks, exprs: &[hir::Expr]) {
 259         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
 260     }
 261
 262     pub fn print_mod(&mut self, _mod: &hir::Mod, attrs: &[ast::Attribute]) {
 263         self.print_inner_attributes(attrs);
 264         for &item_id in &_mod.item_ids {
 265             self.ann.nested(self, Nested::Item(item_id));
 266         }
 267     }
 268
 269     pub fn print_foreign_mod(&mut self,
 270                              nmod: &hir::ForeignMod,
 271                              attrs: &[ast::Attribute])
 272                              {
 273         self.print_inner_attributes(attrs);
 274         for item in &nmod.items {
 275             self.print_foreign_item(item);
 276         }
 277     }
 278
 279     pub fn print_opt_lifetime(&mut self, lifetime: &hir::Lifetime) {
 280         if !lifetime.is_elided() {
 281             self.print_lifetime(lifetime);
 282             self.nbsp();
 283         }
 284     }
 285
 286     pub fn print_type(&mut self, ty: &hir::Ty) {
 287         self.maybe_print_comment(ty.span.lo());
 288         self.ibox(0);
 289         match ty.kind {
 290             hir::TyKind::Slice(ref ty) => {
 291                 self.s.word("[");
 292                 self.print_type(&ty);
 293                 self.s.word("]");
 294             }
 295             hir::TyKind::Ptr(ref mt) => {
 296                 self.s.word("*");
 297                 match mt.mutbl {
 298                     hir::MutMutable => self.word_nbsp("mut"),
 299                     hir::MutImmutable => self.word_nbsp("const"),
 300                 }
 301                 self.print_type(&mt.ty);
 302             }
 303             hir::TyKind::Rptr(ref lifetime, ref mt) => {
 304                 self.s.word("&");
 305                 self.print_opt_lifetime(lifetime);
 306                 self.print_mt(mt);
 307             }
 308             hir::TyKind::Never => {
 309                 self.s.word("!");
 310             },
 311             hir::TyKind::Tup(ref elts) => {
 312                 self.popen();
 313                 self.commasep(Inconsistent, &elts[..], |s, ty| s.print_type(&ty));
 314                 if elts.len() == 1 {
 315                     self.s.word(",");
 316                 }
 317                 self.pclose();
 318             }
 319             hir::TyKind::BareFn(ref f) => {
 320                 self.print_ty_fn(f.abi, f.unsafety, &f.decl, None, &f.generic_params,
 321                                  &f.param_names[..]);
 322             }
 323             hir::TyKind::Def(..) => {},
 324             hir::TyKind::Path(ref qpath) => {
 325                 self.print_qpath(qpath, false)
 326             }
 327             hir::TyKind::TraitObject(ref bounds, ref lifetime) => {
 328                 let mut first = true;
 329                 for bound in bounds {
 330                     if first {
 331                         first = false;
 332                     } else {
 333                         self.nbsp();
 334                         self.word_space("+");
 335                     }
 336                     self.print_poly_trait_ref(bound);
 337                 }
 338                 if !lifetime.is_elided() {
 339                     self.nbsp();
 340                     self.word_space("+");
 341                     self.print_lifetime(lifetime);
 342                 }
 343             }
 344             hir::TyKind::Array(ref ty, ref length) => {
 345                 self.s.word("[");
 346                 self.print_type(&ty);
 347                 self.s.word("; ");
 348                 self.print_anon_const(length);
 349                 self.s.word("]");
 350             }
 351             hir::TyKind::Typeof(ref e) => {
 352                 self.s.word("typeof(");
 353                 self.print_anon_const(e);
 354                 self.s.word(")");
 355             }
 356             hir::TyKind::Infer => {
 357                 self.s.word("_");
 358             }
 359             hir::TyKind::Err => {
 360                 self.popen();
 361                 self.s.word("/*ERROR*/");
 362                 self.pclose();
 363             }
 364             hir::TyKind::CVarArgs(_) => {
 365                 self.s.word("...");
 366             }
 367         }
 368         self.end()
 369     }
 370
 371     pub fn print_foreign_item(&mut self, item: &hir::ForeignItem) {
 372         self.hardbreak_if_not_bol();
 373         self.maybe_print_comment(item.span.lo());
 374         self.print_outer_attributes(&item.attrs);
 375         match item.node {
 376             hir::ForeignItemKind::Fn(ref decl, ref arg_names, ref generics) => {
 377                 self.head("");
 378                 self.print_fn(decl,
 379                               hir::FnHeader {
 380                                   unsafety: hir::Unsafety::Normal,
 381                                   constness: hir::Constness::NotConst,
 382                                   abi: Abi::Rust,
 383                                   asyncness: hir::IsAsync::NotAsync,
 384                               },
 385                               Some(item.ident.name),
 386                               generics,
 387                               &item.vis,
 388                               arg_names,
 389                               None);
 390                 self.end(); // end head-ibox
 391                 self.s.word(";");
 392                 self.end() // end the outer fn box
 393             }
 394             hir::ForeignItemKind::Static(ref t, m) => {
 395                 self.head(visibility_qualified(&item.vis, "static"));
 396                 if m == hir::MutMutable {
 397                     self.word_space("mut");
 398                 }
 399                 self.print_ident(item.ident);
 400                 self.word_space(":");
 401                 self.print_type(&t);
 402                 self.s.word(";");
 403                 self.end(); // end the head-ibox
 404                 self.end() // end the outer cbox
 405             }
 406             hir::ForeignItemKind::Type => {
 407                 self.head(visibility_qualified(&item.vis, "type"));
 408                 self.print_ident(item.ident);
 409                 self.s.word(";");
 410                 self.end(); // end the head-ibox
 411                 self.end() // end the outer cbox
 412             }
 413         }
 414     }
 415
 416     fn print_associated_const(&mut self,
 417                               ident: ast::Ident,
 418                               ty: &hir::Ty,
 419                               default: Option<hir::BodyId>,
 420                               vis: &hir::Visibility)
 421                               {
 422         self.s.word(visibility_qualified(vis, ""));
 423         self.word_space("const");
 424         self.print_ident(ident);
 425         self.word_space(":");
 426         self.print_type(ty);
 427         if let Some(expr) = default {
 428             self.s.space();
 429             self.word_space("=");
 430             self.ann.nested(self, Nested::Body(expr));
 431         }
 432         self.s.word(";")
 433     }
 434
 435     fn print_associated_type(&mut self,
 436                              ident: ast::Ident,
 437                              bounds: Option<&hir::GenericBounds>,
 438                              ty: Option<&hir::Ty>)
 439                              {
 440         self.word_space("type");
 441         self.print_ident(ident);
 442         if let Some(bounds) = bounds {
 443             self.print_bounds(":", bounds);
 444         }
 445         if let Some(ty) = ty {
 446             self.s.space();
 447             self.word_space("=");
 448             self.print_type(ty);
 449         }
 450         self.s.word(";")
 451     }
 452
 453     fn print_item_type(
 454         &mut self,
 455         item: &hir::Item,
 456         generics: &hir::Generics,
 457         inner: impl Fn(&mut Self),
 458     ) {
 459         self.head(visibility_qualified(&item.vis, "type"));
 460         self.print_ident(item.ident);
 461         self.print_generic_params(&generics.params);
 462         self.end(); // end the inner ibox
 463
 464         self.print_where_clause(&generics.where_clause);
 465         self.s.space();
 466         inner(self);
 467         self.s.word(";");
 468         self.end(); // end the outer ibox
 469     }
 470
 471     /// Pretty-print an item
 472     pub fn print_item(&mut self, item: &hir::Item) {
 473         self.hardbreak_if_not_bol();
 474         self.maybe_print_comment(item.span.lo());
 475         self.print_outer_attributes(&item.attrs);
 476         self.ann.pre(self, AnnNode::Item(item));
 477         match item.node {
 478             hir::ItemKind::ExternCrate(orig_name) => {
 479                 self.head(visibility_qualified(&item.vis, "extern crate"));
 480                 if let Some(orig_name) = orig_name {
 481                     self.print_name(orig_name);
 482                     self.s.space();
 483                     self.s.word("as");
 484                     self.s.space();
 485                 }
 486                 self.print_ident(item.ident);
 487                 self.s.word(";");
 488                 self.end(); // end inner head-block
 489                 self.end(); // end outer head-block
 490             }
 491             hir::ItemKind::Use(ref path, kind) => {
 492                 self.head(visibility_qualified(&item.vis, "use"));
 493                 self.print_path(path, false);
 494
 495                 match kind {
 496                     hir::UseKind::Single => {
 497                         if path.segments.last().unwrap().ident != item.ident {
 498                             self.s.space();
 499                             self.word_space("as");
 500                             self.print_ident(item.ident);
 501                         }
 502                         self.s.word(";");
 503                     }
 504                     hir::UseKind::Glob => self.s.word("::*;"),
 505                     hir::UseKind::ListStem => self.s.word("::{};")
 506                 }
 507                 self.end(); // end inner head-block
 508                 self.end(); // end outer head-block
 509             }
 510             hir::ItemKind::Static(ref ty, m, expr) => {
 511                 self.head(visibility_qualified(&item.vis, "static"));
 512                 if m == hir::MutMutable {
 513                     self.word_space("mut");
 514                 }
 515                 self.print_ident(item.ident);
 516                 self.word_space(":");
 517                 self.print_type(&ty);
 518                 self.s.space();
 519                 self.end(); // end the head-ibox
 520
 521                 self.word_space("=");
 522                 self.ann.nested(self, Nested::Body(expr));
 523                 self.s.word(";");
 524                 self.end(); // end the outer cbox
 525             }
 526             hir::ItemKind::Const(ref ty, expr) => {
 527                 self.head(visibility_qualified(&item.vis, "const"));
 528                 self.print_ident(item.ident);
 529                 self.word_space(":");
 530                 self.print_type(&ty);
 531                 self.s.space();
 532                 self.end(); // end the head-ibox
 533
 534                 self.word_space("=");
 535                 self.ann.nested(self, Nested::Body(expr));
 536                 self.s.word(";");
 537                 self.end(); // end the outer cbox
 538             }
 539             hir::ItemKind::Fn(ref decl, header, ref param_names, body) => {
 540                 self.head("");
 541                 self.print_fn(decl,
 542                               header,
 543                               Some(item.ident.name),
 544                               param_names,
 545                               &item.vis,
 546                               &[],
 547                               Some(body));
 548                 self.s.word(" ");
 549                 self.end(); // need to close a box
 550                 self.end(); // need to close a box
 551                 self.ann.nested(self, Nested::Body(body));
 552             }
 553             hir::ItemKind::Mod(ref _mod) => {
 554                 self.head(visibility_qualified(&item.vis, "mod"));
 555                 self.print_ident(item.ident);
 556                 self.nbsp();
 557                 self.bopen();
 558                 self.print_mod(_mod, &item.attrs);
 559                 self.bclose(item.span);
 560             }
 561             hir::ItemKind::ForeignMod(ref nmod) => {
 562                 self.head("extern");
 563                 self.word_nbsp(nmod.abi.to_string());
 564                 self.bopen();
 565                 self.print_foreign_mod(nmod, &item.attrs);
 566                 self.bclose(item.span);
 567             }
 568             hir::ItemKind::GlobalAsm(ref ga) => {
 569                 self.head(visibility_qualified(&item.vis, "global asm"));
 570                 self.s.word(ga.asm.as_str().to_string());
 571                 self.end()
 572             }
 573             hir::ItemKind::TyAlias(ref ty, ref generics) => {
 574                 self.print_item_type(item, &generics, |state| {
 575                     state.word_space("=");
 576                     state.print_type(&ty);
 577                 });
 578             }
 579             hir::ItemKind::OpaqueTy(ref opaque_ty) => {
 580                 self.print_item_type(item, &opaque_ty.generics, |state| {
 581                     let mut real_bounds = Vec::with_capacity(opaque_ty.bounds.len());
 582                     for b in opaque_ty.bounds.iter() {
 583                         if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 584                             state.s.space();
 585                             state.word_space("for ?");
 586                             state.print_trait_ref(&ptr.trait_ref);
 587                         } else {
 588                             real_bounds.push(b);
 589                         }
 590                     }
 591                     state.print_bounds("= impl", real_bounds);
 592                 });
 593             }
 594             hir::ItemKind::Enum(ref enum_definition, ref params) => {
 595                 self.print_enum_def(enum_definition, params, item.ident.name, item.span, &item.vis);
 596             }
 597             hir::ItemKind::Struct(ref struct_def, ref generics) => {
 598                 self.head(visibility_qualified(&item.vis, "struct"));
 599                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
 600             }
 601             hir::ItemKind::Union(ref struct_def, ref generics) => {
 602                 self.head(visibility_qualified(&item.vis, "union"));
 603                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
 604             }
 605             hir::ItemKind::Impl(unsafety,
 606                           polarity,
 607                           defaultness,
 608                           ref generics,
 609                           ref opt_trait,
 610                           ref ty,
 611                           ref impl_items) => {
 612                 self.head("");
 613                 self.print_visibility(&item.vis);
 614                 self.print_defaultness(defaultness);
 615                 self.print_unsafety(unsafety);
 616                 self.word_nbsp("impl");
 617
 618                 if !generics.params.is_empty() {
 619                     self.print_generic_params(&generics.params);
 620                     self.s.space();
 621                 }
 622
 623                 if let hir::ImplPolarity::Negative = polarity {
 624                     self.s.word("!");
 625                 }
 626
 627                 if let Some(ref t) = opt_trait {
 628                     self.print_trait_ref(t);
 629                     self.s.space();
 630                     self.word_space("for");
 631                 }
 632
 633                 self.print_type(&ty);
 634                 self.print_where_clause(&generics.where_clause);
 635
 636                 self.s.space();
 637                 self.bopen();
 638                 self.print_inner_attributes(&item.attrs);
 639                 for impl_item in impl_items {
 640                     self.ann.nested(self, Nested::ImplItem(impl_item.id));
 641                 }
 642                 self.bclose(item.span);
 643             }
 644             hir::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref trait_items) => {
 645                 self.head("");
 646                 self.print_visibility(&item.vis);
 647                 self.print_is_auto(is_auto);
 648                 self.print_unsafety(unsafety);
 649                 self.word_nbsp("trait");
 650                 self.print_ident(item.ident);
 651                 self.print_generic_params(&generics.params);
 652                 let mut real_bounds = Vec::with_capacity(bounds.len());
 653                 for b in bounds.iter() {
 654                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 655                         self.s.space();
 656                         self.word_space("for ?");
 657                         self.print_trait_ref(&ptr.trait_ref);
 658                     } else {
 659                         real_bounds.push(b);
 660                     }
 661                 }
 662                 self.print_bounds(":", real_bounds);
 663                 self.print_where_clause(&generics.where_clause);
 664                 self.s.word(" ");
 665                 self.bopen();
 666                 for trait_item in trait_items {
 667                     self.ann.nested(self, Nested::TraitItem(trait_item.id));
 668                 }
 669                 self.bclose(item.span);
 670             }
 671             hir::ItemKind::TraitAlias(ref generics, ref bounds) => {
 672                 self.head("");
 673                 self.print_visibility(&item.vis);
 674                 self.word_nbsp("trait");
 675                 self.print_ident(item.ident);
 676                 self.print_generic_params(&generics.params);
 677                 let mut real_bounds = Vec::with_capacity(bounds.len());
 678                 // FIXME(durka) this seems to be some quite outdated syntax
 679                 for b in bounds.iter() {
 680                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 681                         self.s.space();
 682                         self.word_space("for ?");
 683                         self.print_trait_ref(&ptr.trait_ref);
 684                     } else {
 685                         real_bounds.push(b);
 686                     }
 687                 }
 688                 self.nbsp();
 689                 self.print_bounds("=", real_bounds);
 690                 self.print_where_clause(&generics.where_clause);
 691                 self.s.word(";");
 692             }
 693         }
 694         self.ann.post(self, AnnNode::Item(item))
 695     }
 696
 697     pub fn print_trait_ref(&mut self, t: &hir::TraitRef) {
 698         self.print_path(&t.path, false)
 699     }
 700
 701     fn print_formal_generic_params(
 702         &mut self,
 703         generic_params: &[hir::GenericParam]
 704     ) {
 705         if !generic_params.is_empty() {
 706             self.s.word("for");
 707             self.print_generic_params(generic_params);
 708             self.nbsp();
 709         }
 710     }
 711
 712     fn print_poly_trait_ref(&mut self, t: &hir::PolyTraitRef) {
 713         self.print_formal_generic_params(&t.bound_generic_params);
 714         self.print_trait_ref(&t.trait_ref)
 715     }
 716
 717     pub fn print_enum_def(&mut self,
 718                           enum_definition: &hir::EnumDef,
 719                           generics: &hir::Generics,
 720                           name: ast::Name,
 721                           span: syntax_pos::Span,
 722                           visibility: &hir::Visibility)
 723                           {
 724         self.head(visibility_qualified(visibility, "enum"));
 725         self.print_name(name);
 726         self.print_generic_params(&generics.params);
 727         self.print_where_clause(&generics.where_clause);
 728         self.s.space();
 729         self.print_variants(&enum_definition.variants, span)
 730     }
 731
 732     pub fn print_variants(&mut self,
 733                           variants: &[hir::Variant],
 734                           span: syntax_pos::Span)
 735                           {
 736         self.bopen();
 737         for v in variants {
 738             self.space_if_not_bol();
 739             self.maybe_print_comment(v.span.lo());
 740             self.print_outer_attributes(&v.attrs);
 741             self.ibox(INDENT_UNIT);
 742             self.print_variant(v);
 743             self.s.word(",");
 744             self.end();
 745             self.maybe_print_trailing_comment(v.span, None);
 746         }
 747         self.bclose(span)
 748     }
 749
 750     pub fn print_visibility(&mut self, vis: &hir::Visibility) {
 751         match vis.node {
 752             hir::VisibilityKind::Public => self.word_nbsp("pub"),
 753             hir::VisibilityKind::Crate(ast::CrateSugar::JustCrate) => self.word_nbsp("crate"),
 754             hir::VisibilityKind::Crate(ast::CrateSugar::PubCrate) => self.word_nbsp("pub(crate)"),
 755             hir::VisibilityKind::Restricted { ref path, .. } => {
 756                 self.s.word("pub(");
 757                 if path.segments.len() == 1 &&
 758                    path.segments[0].ident.name == kw::Super {
 759                     // Special case: `super` can print like `pub(super)`.
 760                     self.s.word("super");
 761                 } else {
 762                     // Everything else requires `in` at present.
 763                     self.word_nbsp("in");
 764                     self.print_path(path, false);
 765                 }
 766                 self.word_nbsp(")");
 767             }
 768             hir::VisibilityKind::Inherited => ()
 769         }
 770     }
 771
 772     pub fn print_defaultness(&mut self, defaultness: hir::Defaultness) {
 773         match defaultness {
 774             hir::Defaultness::Default { .. } => self.word_nbsp("default"),
 775             hir::Defaultness::Final => (),
 776         }
 777     }
 778
 779     pub fn print_struct(&mut self,
 780                         struct_def: &hir::VariantData,
 781                         generics: &hir::Generics,
 782                         name: ast::Name,
 783                         span: syntax_pos::Span,
 784                         print_finalizer: bool)
 785                         {
 786         self.print_name(name);
 787         self.print_generic_params(&generics.params);
 788         match struct_def {
 789             hir::VariantData::Tuple(..) | hir::VariantData::Unit(..) => {
 790                 if let hir::VariantData::Tuple(..) = struct_def {
 791                     self.popen();
 792                     self.commasep(Inconsistent, struct_def.fields(), |s, field| {
 793                         s.maybe_print_comment(field.span.lo());
 794                         s.print_outer_attributes(&field.attrs);
 795                         s.print_visibility(&field.vis);
 796                         s.print_type(&field.ty)
 797                     });
 798                     self.pclose();
 799                 }
 800                 self.print_where_clause(&generics.where_clause);
 801                 if print_finalizer {
 802                     self.s.word(";");
 803                 }
 804                 self.end();
 805                 self.end() // close the outer-box
 806             }
 807             hir::VariantData::Struct(..) => {
 808                 self.print_where_clause(&generics.where_clause);
 809                 self.nbsp();
 810                 self.bopen();
 811                 self.hardbreak_if_not_bol();
 812
 813                 for field in struct_def.fields() {
 814                     self.hardbreak_if_not_bol();
 815                     self.maybe_print_comment(field.span.lo());
 816                     self.print_outer_attributes(&field.attrs);
 817                     self.print_visibility(&field.vis);
 818                     self.print_ident(field.ident);
 819                     self.word_nbsp(":");
 820                     self.print_type(&field.ty);
 821                     self.s.word(",");
 822                 }
 823
 824                 self.bclose(span)
 825             }
 826         }
 827     }
 828
 829     pub fn print_variant(&mut self, v: &hir::Variant) {
 830         self.head("");
 831         let generics = hir::Generics::empty();
 832         self.print_struct(&v.data, &generics, v.ident.name, v.span, false);
 833         if let Some(ref d) = v.disr_expr {
 834             self.s.space();
 835             self.word_space("=");
 836             self.print_anon_const(d);
 837         }
 838     }
 839     pub fn print_method_sig(&mut self,
 840                             ident: ast::Ident,
 841                             m: &hir::MethodSig,
 842                             generics: &hir::Generics,
 843                             vis: &hir::Visibility,
 844                             arg_names: &[ast::Ident],
 845                             body_id: Option<hir::BodyId>)
 846                             {
 847         self.print_fn(&m.decl,
 848                       m.header,
 849                       Some(ident.name),
 850                       generics,
 851                       vis,
 852                       arg_names,
 853                       body_id)
 854     }
 855
 856     pub fn print_trait_item(&mut self, ti: &hir::TraitItem) {
 857         self.ann.pre(self, AnnNode::SubItem(ti.hir_id));
 858         self.hardbreak_if_not_bol();
 859         self.maybe_print_comment(ti.span.lo());
 860         self.print_outer_attributes(&ti.attrs);
 861         match ti.kind {
 862             hir::TraitItemKind::Const(ref ty, default) => {
 863                 let vis = Spanned { span: syntax_pos::DUMMY_SP,
 864                                     node: hir::VisibilityKind::Inherited };
 865                 self.print_associated_const(ti.ident, &ty, default, &vis);
 866             }
 867             hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Required(ref arg_names)) => {
 868                 let vis = Spanned { span: syntax_pos::DUMMY_SP,
 869                                     node: hir::VisibilityKind::Inherited };
 870                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, arg_names, None);
 871                 self.s.word(";");
 872             }
 873             hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Provided(body)) => {
 874                 let vis = Spanned { span: syntax_pos::DUMMY_SP,
 875                                     node: hir::VisibilityKind::Inherited };
 876                 self.head("");
 877                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, &[], Some(body));
 878                 self.nbsp();
 879                 self.end(); // need to close a box
 880                 self.end(); // need to close a box
 881                 self.ann.nested(self, Nested::Body(body));
 882             }
 883             hir::TraitItemKind::Type(ref bounds, ref default) => {
 884                 self.print_associated_type(ti.ident,
 885                                            Some(bounds),
 886                                            default.as_ref().map(|ty| &**ty));
 887             }
 888         }
 889         self.ann.post(self, AnnNode::SubItem(ti.hir_id))
 890     }
 891
 892     pub fn print_impl_item(&mut self, ii: &hir::ImplItem) {
 893         self.ann.pre(self, AnnNode::SubItem(ii.hir_id));
 894         self.hardbreak_if_not_bol();
 895         self.maybe_print_comment(ii.span.lo());
 896         self.print_outer_attributes(&ii.attrs);
 897         self.print_defaultness(ii.defaultness);
 898
 899         match ii.kind {
 900             hir::ImplItemKind::Const(ref ty, expr) => {
 901                 self.print_associated_const(ii.ident, &ty, Some(expr), &ii.vis);
 902             }
 903             hir::ImplItemKind::Method(ref sig, body) => {
 904                 self.head("");
 905                 self.print_method_sig(ii.ident, sig, &ii.generics, &ii.vis, &[], Some(body));
 906                 self.nbsp();
 907                 self.end(); // need to close a box
 908                 self.end(); // need to close a box
 909                 self.ann.nested(self, Nested::Body(body));
 910             }
 911             hir::ImplItemKind::TyAlias(ref ty) => {
 912                 self.print_associated_type(ii.ident, None, Some(ty));
 913             }
 914             hir::ImplItemKind::OpaqueTy(ref bounds) => {
 915                 self.word_space("type");
 916                 self.print_ident(ii.ident);
 917                 self.print_bounds("= impl", bounds);
 918                 self.s.word(";");
 919             }
 920         }
 921         self.ann.post(self, AnnNode::SubItem(ii.hir_id))
 922     }
 923
 924     pub fn print_local(
 925         &mut self,
 926         init: Option<&hir::Expr>,
 927         decl: impl Fn(&mut Self)
 928     ) {
 929         self.space_if_not_bol();
 930         self.ibox(INDENT_UNIT);
 931         self.word_nbsp("let");
 932
 933         self.ibox(INDENT_UNIT);
 934         decl(self);
 935         self.end();
 936
 937         if let Some(ref init) = init {
 938             self.nbsp();
 939             self.word_space("=");
 940             self.print_expr(&init);
 941         }
 942         self.end()
 943     }
 944
 945     pub fn print_stmt(&mut self, st: &hir::Stmt) {
 946         self.maybe_print_comment(st.span.lo());
 947         match st.kind {
 948             hir::StmtKind::Local(ref loc) => {
 949                 self.print_local(loc.init.as_deref(), |this| this.print_local_decl(&loc));
 950             }
 951             hir::StmtKind::Item(item) => {
 952                 self.ann.nested(self, Nested::Item(item))
 953             }
 954             hir::StmtKind::Expr(ref expr) => {
 955                 self.space_if_not_bol();
 956                 self.print_expr(&expr);
 957             }
 958             hir::StmtKind::Semi(ref expr) => {
 959                 self.space_if_not_bol();
 960                 self.print_expr(&expr);
 961                 self.s.word(";");
 962             }
 963         }
 964         if stmt_ends_with_semi(&st.kind) {
 965             self.s.word(";");
 966         }
 967         self.maybe_print_trailing_comment(st.span, None)
 968     }
 969
 970     pub fn print_block(&mut self, blk: &hir::Block) {
 971         self.print_block_with_attrs(blk, &[])
 972     }
 973
 974     pub fn print_block_unclosed(&mut self, blk: &hir::Block) {
 975         self.print_block_maybe_unclosed(blk, &[], false)
 976     }
 977
 978     pub fn print_block_with_attrs(&mut self,
 979                                   blk: &hir::Block,
 980                                   attrs: &[ast::Attribute])
 981                                   {
 982         self.print_block_maybe_unclosed(blk, attrs, true)
 983     }
 984
 985     pub fn print_block_maybe_unclosed(&mut self,
 986                                       blk: &hir::Block,
 987                                       attrs: &[ast::Attribute],
 988                                       close_box: bool)
 989                                       {
 990         match blk.rules {
 991             hir::UnsafeBlock(..) => self.word_space("unsafe"),
 992             hir::PushUnsafeBlock(..) => self.word_space("push_unsafe"),
 993             hir::PopUnsafeBlock(..) => self.word_space("pop_unsafe"),
 994             hir::DefaultBlock => (),
 995         }
 996         self.maybe_print_comment(blk.span.lo());
 997         self.ann.pre(self, AnnNode::Block(blk));
 998         self.bopen();
 999
1000         self.print_inner_attributes(attrs);
1001
1002         for st in &blk.stmts {
1003             self.print_stmt(st);
1004         }
1005         if let Some(ref expr) = blk.expr {
1006             self.space_if_not_bol();
1007             self.print_expr(&expr);
1008             self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
1009         }
1010         self.bclose_maybe_open(blk.span, close_box);
1011         self.ann.post(self, AnnNode::Block(blk))
1012     }
1013
1014     pub fn print_anon_const(&mut self, constant: &hir::AnonConst) {
1015         self.ann.nested(self, Nested::Body(constant.body))
1016     }
1017
1018     fn print_call_post(&mut self, args: &[hir::Expr]) {
1019         self.popen();
1020         self.commasep_exprs(Inconsistent, args);
1021         self.pclose()
1022     }
1023
1024     pub fn print_expr_maybe_paren(&mut self, expr: &hir::Expr, prec: i8) {
1025         let needs_par = expr.precedence().order() < prec;
1026         if needs_par {
1027             self.popen();
1028         }
1029         self.print_expr(expr);
1030         if needs_par {
1031             self.pclose();
1032         }
1033     }
1034
1035     /// Print an expr using syntax that's acceptable in a condition position, such as the `cond` in
1036     /// `if cond { ... }`.
1037     pub fn print_expr_as_cond(&mut self, expr: &hir::Expr) {
1038         let needs_par = match expr.kind {
1039             // These cases need parens due to the parse error observed in #26461: `if return {}`
1040             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1041             hir::ExprKind::Closure(..) |
1042             hir::ExprKind::Ret(..) |
1043             hir::ExprKind::Break(..) => true,
1044
1045             _ => contains_exterior_struct_lit(expr),
1046         };
1047
1048         if needs_par {
1049             self.popen();
1050         }
1051         self.print_expr(expr);
1052         if needs_par {
1053             self.pclose();
1054         }
1055     }
1056
1057     fn print_expr_vec(&mut self, exprs: &[hir::Expr]) {
1058         self.ibox(INDENT_UNIT);
1059         self.s.word("[");
1060         self.commasep_exprs(Inconsistent, exprs);
1061         self.s.word("]");
1062         self.end()
1063     }
1064
1065     fn print_expr_repeat(&mut self, element: &hir::Expr, count: &hir::AnonConst) {
1066         self.ibox(INDENT_UNIT);
1067         self.s.word("[");
1068         self.print_expr(element);
1069         self.word_space(";");
1070         self.print_anon_const(count);
1071         self.s.word("]");
1072         self.end()
1073     }
1074
1075     fn print_expr_struct(&mut self,
1076                          qpath: &hir::QPath,
1077                          fields: &[hir::Field],
1078                          wth: &Option<P<hir::Expr>>)
1079                          {
1080         self.print_qpath(qpath, true);
1081         self.s.word("{");
1082         self.commasep_cmnt(Consistent,
1083                            &fields[..],
1084                            |s, field| {
1085                                s.ibox(INDENT_UNIT);
1086                                if !field.is_shorthand {
1087                                     s.print_ident(field.ident);
1088                                     s.word_space(":");
1089                                }
1090                                s.print_expr(&field.expr);
1091                                s.end()
1092                            },
1093                            |f| f.span);
1094         match *wth {
1095             Some(ref expr) => {
1096                 self.ibox(INDENT_UNIT);
1097                 if !fields.is_empty() {
1098                     self.s.word(",");
1099                     self.s.space();
1100                 }
1101                 self.s.word("..");
1102                 self.print_expr(&expr);
1103                 self.end();
1104             }
1105             _ => if !fields.is_empty() {
1106                 self.s.word(",")
1107             },
1108         }
1109         self.s.word("}");
1110     }
1111
1112     fn print_expr_tup(&mut self, exprs: &[hir::Expr]) {
1113         self.popen();
1114         self.commasep_exprs(Inconsistent, exprs);
1115         if exprs.len() == 1 {
1116             self.s.word(",");
1117         }
1118         self.pclose()
1119     }
1120
1121     fn print_expr_call(&mut self, func: &hir::Expr, args: &[hir::Expr]) {
1122         let prec = match func.kind {
1123             hir::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1124             _ => parser::PREC_POSTFIX,
1125         };
1126
1127         self.print_expr_maybe_paren(func, prec);
1128         self.print_call_post(args)
1129     }
1130
1131     fn print_expr_method_call(&mut self,
1132                               segment: &hir::PathSegment,
1133                               args: &[hir::Expr])
1134                               {
1135         let base_args = &args[1..];
1136         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
1137         self.s.word(".");
1138         self.print_ident(segment.ident);
1139
1140         let generic_args = segment.generic_args();
1141         if !generic_args.args.is_empty() || !generic_args.bindings.is_empty() {
1142             self.print_generic_args(generic_args, segment.infer_args, true);
1143         }
1144
1145         self.print_call_post(base_args)
1146     }
1147
1148     fn print_expr_binary(&mut self,
1149                          op: hir::BinOp,
1150                          lhs: &hir::Expr,
1151                          rhs: &hir::Expr)
1152                          {
1153         let assoc_op = bin_op_to_assoc_op(op.node);
1154         let prec = assoc_op.precedence() as i8;
1155         let fixity = assoc_op.fixity();
1156
1157         let (left_prec, right_prec) = match fixity {
1158             Fixity::Left => (prec, prec + 1),
1159             Fixity::Right => (prec + 1, prec),
1160             Fixity::None => (prec + 1, prec + 1),
1161         };
1162
1163         let left_prec = match (&lhs.kind, op.node) {
1164             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1165             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1166             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1167             (&hir::ExprKind::Cast { .. }, hir::BinOpKind::Lt) |
1168             (&hir::ExprKind::Cast { .. }, hir::BinOpKind::Shl) => parser::PREC_FORCE_PAREN,
1169             _ => left_prec,
1170         };
1171
1172         self.print_expr_maybe_paren(lhs, left_prec);
1173         self.s.space();
1174         self.word_space(op.node.as_str());
1175         self.print_expr_maybe_paren(rhs, right_prec)
1176     }
1177
1178     fn print_expr_unary(&mut self, op: hir::UnOp, expr: &hir::Expr) {
1179         self.s.word(op.as_str());
1180         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1181     }
1182
1183     fn print_expr_addr_of(&mut self,
1184                           mutability: hir::Mutability,
1185                           expr: &hir::Expr)
1186                           {
1187         self.s.word("&");
1188         self.print_mutability(mutability);
1189         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1190     }
1191
1192     fn print_literal(&mut self, lit: &hir::Lit) {
1193         self.maybe_print_comment(lit.span.lo());
1194         self.word(lit.node.to_lit_token().to_string())
1195     }
1196
1197     pub fn print_expr(&mut self, expr: &hir::Expr) {
1198         self.maybe_print_comment(expr.span.lo());
1199         self.print_outer_attributes(&expr.attrs);
1200         self.ibox(INDENT_UNIT);
1201         self.ann.pre(self, AnnNode::Expr(expr));
1202         match expr.kind {
1203             hir::ExprKind::Box(ref expr) => {
1204                 self.word_space("box");
1205                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX);
1206             }
1207             hir::ExprKind::Array(ref exprs) => {
1208                 self.print_expr_vec(exprs);
1209             }
1210             hir::ExprKind::Repeat(ref element, ref count) => {
1211                 self.print_expr_repeat(&element, count);
1212             }
1213             hir::ExprKind::Struct(ref qpath, ref fields, ref wth) => {
1214                 self.print_expr_struct(qpath, &fields[..], wth);
1215             }
1216             hir::ExprKind::Tup(ref exprs) => {
1217                 self.print_expr_tup(exprs);
1218             }
1219             hir::ExprKind::Call(ref func, ref args) => {
1220                 self.print_expr_call(&func, args);
1221             }
1222             hir::ExprKind::MethodCall(ref segment, _, ref args) => {
1223                 self.print_expr_method_call(segment, args);
1224             }
1225             hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
1226                 self.print_expr_binary(op, &lhs, &rhs);
1227             }
1228             hir::ExprKind::Unary(op, ref expr) => {
1229                 self.print_expr_unary(op, &expr);
1230             }
1231             hir::ExprKind::AddrOf(m, ref expr) => {
1232                 self.print_expr_addr_of(m, &expr);
1233             }
1234             hir::ExprKind::Lit(ref lit) => {
1235                 self.print_literal(&lit);
1236             }
1237             hir::ExprKind::Cast(ref expr, ref ty) => {
1238                 let prec = AssocOp::As.precedence() as i8;
1239                 self.print_expr_maybe_paren(&expr, prec);
1240                 self.s.space();
1241                 self.word_space("as");
1242                 self.print_type(&ty);
1243             }
1244             hir::ExprKind::Type(ref expr, ref ty) => {
1245                 let prec = AssocOp::Colon.precedence() as i8;
1246                 self.print_expr_maybe_paren(&expr, prec);
1247                 self.word_space(":");
1248                 self.print_type(&ty);
1249             }
1250             hir::ExprKind::DropTemps(ref init) => {
1251                 // Print `{`:
1252                 self.cbox(INDENT_UNIT);
1253                 self.ibox(0);
1254                 self.bopen();
1255
1256                 // Print `let _t = $init;`:
1257                 let temp = ast::Ident::from_str("_t");
1258                 self.print_local(Some(init), |this| this.print_ident(temp));
1259                 self.s.word(";");
1260
1261                 // Print `_t`:
1262                 self.space_if_not_bol();
1263                 self.print_ident(temp);
1264
1265                 // Print `}`:
1266                 self.bclose_maybe_open(expr.span, true);
1267             }
1268             hir::ExprKind::Loop(ref blk, opt_label, _) => {
1269                 if let Some(label) = opt_label {
1270                     self.print_ident(label.ident);
1271                     self.word_space(":");
1272                 }
1273                 self.head("loop");
1274                 self.s.space();
1275                 self.print_block(&blk);
1276             }
1277             hir::ExprKind::Match(ref expr, ref arms, _) => {
1278                 self.cbox(INDENT_UNIT);
1279                 self.ibox(INDENT_UNIT);
1280                 self.word_nbsp("match");
1281                 self.print_expr_as_cond(&expr);
1282                 self.s.space();
1283                 self.bopen();
1284                 for arm in arms {
1285                     self.print_arm(arm);
1286                 }
1287                 self.bclose(expr.span);
1288             }
1289             hir::ExprKind::Closure(capture_clause, ref decl, body, _fn_decl_span, _gen) => {
1290                 self.print_capture_clause(capture_clause);
1291
1292                 self.print_closure_params(&decl, body);
1293                 self.s.space();
1294
1295                 // This is a bare expression.
1296                 self.ann.nested(self, Nested::Body(body));
1297                 self.end(); // need to close a box
1298
1299                 // A box will be closed by `print_expr`, but we didn't want an overall
1300                 // wrapper so we closed the corresponding opening. so create an
1301                 // empty box to satisfy the close.
1302                 self.ibox(0);
1303             }
1304             hir::ExprKind::Block(ref blk, opt_label) => {
1305                 if let Some(label) = opt_label {
1306                     self.print_ident(label.ident);
1307                     self.word_space(":");
1308                 }
1309                 // containing cbox, will be closed by print-block at `}`
1310                 self.cbox(INDENT_UNIT);
1311                 // head-box, will be closed by print-block after `{`
1312                 self.ibox(0);
1313                 self.print_block(&blk);
1314             }
1315             hir::ExprKind::Assign(ref lhs, ref rhs) => {
1316                 let prec = AssocOp::Assign.precedence() as i8;
1317                 self.print_expr_maybe_paren(&lhs, prec + 1);
1318                 self.s.space();
1319                 self.word_space("=");
1320                 self.print_expr_maybe_paren(&rhs, prec);
1321             }
1322             hir::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
1323                 let prec = AssocOp::Assign.precedence() as i8;
1324                 self.print_expr_maybe_paren(&lhs, prec + 1);
1325                 self.s.space();
1326                 self.s.word(op.node.as_str());
1327                 self.word_space("=");
1328                 self.print_expr_maybe_paren(&rhs, prec);
1329             }
1330             hir::ExprKind::Field(ref expr, ident) => {
1331                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
1332                 self.s.word(".");
1333                 self.print_ident(ident);
1334             }
1335             hir::ExprKind::Index(ref expr, ref index) => {
1336                 self.print_expr_maybe_paren(&expr, parser::PREC_POSTFIX);
1337                 self.s.word("[");
1338                 self.print_expr(&index);
1339                 self.s.word("]");
1340             }
1341             hir::ExprKind::Path(ref qpath) => {
1342                 self.print_qpath(qpath, true)
1343             }
1344             hir::ExprKind::Break(destination, ref opt_expr) => {
1345                 self.s.word("break");
1346                 self.s.space();
1347                 if let Some(label) = destination.label {
1348                     self.print_ident(label.ident);
1349                     self.s.space();
1350                 }
1351                 if let Some(ref expr) = *opt_expr {
1352                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
1353                     self.s.space();
1354                 }
1355             }
1356             hir::ExprKind::Continue(destination) => {
1357                 self.s.word("continue");
1358                 self.s.space();
1359                 if let Some(label) = destination.label {
1360                     self.print_ident(label.ident);
1361                     self.s.space()
1362                 }
1363             }
1364             hir::ExprKind::Ret(ref result) => {
1365                 self.s.word("return");
1366                 if let Some(ref expr) = *result {
1367                     self.s.word(" ");
1368                     self.print_expr_maybe_paren(&expr, parser::PREC_JUMP);
1369                 }
1370             }
1371             hir::ExprKind::InlineAsm(ref a, ref outputs, ref inputs) => {
1372                 self.s.word("asm!");
1373                 self.popen();
1374                 self.print_string(&a.asm.as_str(), a.asm_str_style);
1375                 self.word_space(":");
1376
1377                 let mut out_idx = 0;
1378                 self.commasep(Inconsistent, &a.outputs, |s, out| {
1379                     let constraint = out.constraint.as_str();
1380                     let mut ch = constraint.chars();
1381                     match ch.next() {
1382                         Some('=') if out.is_rw => {
1383                             s.print_string(&format!("+{}", ch.as_str()),
1384                                            ast::StrStyle::Cooked)
1385                         }
1386                         _ => s.print_string(&constraint, ast::StrStyle::Cooked),
1387                     }
1388                     s.popen();
1389                     s.print_expr(&outputs[out_idx]);
1390                     s.pclose();
1391                     out_idx += 1;
1392                 });
1393                 self.s.space();
1394                 self.word_space(":");
1395
1396                 let mut in_idx = 0;
1397                 self.commasep(Inconsistent, &a.inputs, |s, co| {
1398                     s.print_string(&co.as_str(), ast::StrStyle::Cooked);
1399                     s.popen();
1400                     s.print_expr(&inputs[in_idx]);
1401                     s.pclose();
1402                     in_idx += 1;
1403                 });
1404                 self.s.space();
1405                 self.word_space(":");
1406
1407                 self.commasep(Inconsistent, &a.clobbers, |s, co| {
1408                     s.print_string(&co.as_str(), ast::StrStyle::Cooked);
1409                 });
1410
1411                 let mut options = vec![];
1412                 if a.volatile {
1413                     options.push("volatile");
1414                 }
1415                 if a.alignstack {
1416                     options.push("alignstack");
1417                 }
1418                 if a.dialect == ast::AsmDialect::Intel {
1419                     options.push("intel");
1420                 }
1421
1422                 if !options.is_empty() {
1423                     self.s.space();
1424                     self.word_space(":");
1425                     self.commasep(Inconsistent, &options, |s, &co| {
1426                         s.print_string(co, ast::StrStyle::Cooked);
1427                     });
1428                 }
1429
1430                 self.pclose();
1431             }
1432             hir::ExprKind::Yield(ref expr, _) => {
1433                 self.word_space("yield");
1434                 self.print_expr_maybe_paren(&expr, parser::PREC_JUMP);
1435             }
1436             hir::ExprKind::Err => {
1437                 self.popen();
1438                 self.s.word("/*ERROR*/");
1439                 self.pclose();
1440             }
1441         }
1442         self.ann.post(self, AnnNode::Expr(expr));
1443         self.end()
1444     }
1445
1446     pub fn print_local_decl(&mut self, loc: &hir::Local) {
1447         self.print_pat(&loc.pat);
1448         if let Some(ref ty) = loc.ty {
1449             self.word_space(":");
1450             self.print_type(&ty);
1451         }
1452     }
1453
1454     pub fn print_usize(&mut self, i: usize) {
1455         self.s.word(i.to_string())
1456     }
1457
1458     pub fn print_name(&mut self, name: ast::Name) {
1459         self.print_ident(ast::Ident::with_dummy_span(name))
1460     }
1461
1462     pub fn print_for_decl(&mut self, loc: &hir::Local, coll: &hir::Expr) {
1463         self.print_local_decl(loc);
1464         self.s.space();
1465         self.word_space("in");
1466         self.print_expr(coll)
1467     }
1468
1469     pub fn print_path(&mut self,
1470                       path: &hir::Path,
1471                       colons_before_params: bool)
1472                       {
1473         self.maybe_print_comment(path.span.lo());
1474
1475         for (i, segment) in path.segments.iter().enumerate() {
1476             if i > 0 {
1477                 self.s.word("::")
1478             }
1479             if segment.ident.name != kw::PathRoot {
1480                 self.print_ident(segment.ident);
1481                 self.print_generic_args(segment.generic_args(), segment.infer_args,
1482                                         colons_before_params);
1483             }
1484         }
1485     }
1486
1487     pub fn print_path_segment(&mut self, segment: &hir::PathSegment) {
1488         if segment.ident.name != kw::PathRoot {
1489             self.print_ident(segment.ident);
1490             self.print_generic_args(segment.generic_args(), segment.infer_args, false);
1491         }
1492     }
1493
1494     pub fn print_qpath(&mut self,
1495                        qpath: &hir::QPath,
1496                        colons_before_params: bool)
1497                        {
1498         match *qpath {
1499             hir::QPath::Resolved(None, ref path) => {
1500                 self.print_path(path, colons_before_params)
1501             }
1502             hir::QPath::Resolved(Some(ref qself), ref path) => {
1503                 self.s.word("<");
1504                 self.print_type(qself);
1505                 self.s.space();
1506                 self.word_space("as");
1507
1508                 for (i, segment) in path.segments[..path.segments.len() - 1].iter().enumerate() {
1509                     if i > 0 {
1510                         self.s.word("::")
1511                     }
1512                     if segment.ident.name != kw::PathRoot {
1513                         self.print_ident(segment.ident);
1514                         self.print_generic_args(segment.generic_args(),
1515                                                 segment.infer_args,
1516                                                 colons_before_params);
1517                     }
1518                 }
1519
1520                 self.s.word(">");
1521                 self.s.word("::");
1522                 let item_segment = path.segments.last().unwrap();
1523                 self.print_ident(item_segment.ident);
1524                 self.print_generic_args(item_segment.generic_args(),
1525                                         item_segment.infer_args,
1526                                         colons_before_params)
1527             }
1528             hir::QPath::TypeRelative(ref qself, ref item_segment) => {
1529                 self.s.word("<");
1530                 self.print_type(qself);
1531                 self.s.word(">");
1532                 self.s.word("::");
1533                 self.print_ident(item_segment.ident);
1534                 self.print_generic_args(item_segment.generic_args(),
1535                                         item_segment.infer_args,
1536                                         colons_before_params)
1537             }
1538         }
1539     }
1540
1541     fn print_generic_args(&mut self,
1542                              generic_args: &hir::GenericArgs,
1543                              infer_args: bool,
1544                              colons_before_params: bool)
1545                              {
1546         if generic_args.parenthesized {
1547             self.s.word("(");
1548             self.commasep(Inconsistent, generic_args.inputs(), |s, ty| s.print_type(&ty));
1549             self.s.word(")");
1550
1551             self.space_if_not_bol();
1552             self.word_space("->");
1553             self.print_type(generic_args.bindings[0].ty());
1554         } else {
1555             let start = if colons_before_params { "::<" } else { "<" };
1556             let empty = Cell::new(true);
1557             let start_or_comma = |this: &mut Self| {
1558                 if empty.get() {
1559                     empty.set(false);
1560                     this.s.word(start)
1561                 } else {
1562                     this.word_space(",")
1563                 }
1564             };
1565
1566             let mut nonelided_generic_args: bool = false;
1567             let elide_lifetimes = generic_args.args.iter().all(|arg| match arg {
1568                 GenericArg::Lifetime(lt) => lt.is_elided(),
1569                 _ => {
1570                     nonelided_generic_args = true;
1571                     true
1572                 }
1573             });
1574
1575             if nonelided_generic_args {
1576                 start_or_comma(self);
1577                 self.commasep(Inconsistent, &generic_args.args, |s, generic_arg| {
1578                     match generic_arg {
1579                         GenericArg::Lifetime(lt) if !elide_lifetimes => s.print_lifetime(lt),
1580                         GenericArg::Lifetime(_) => {},
1581                         GenericArg::Type(ty) => s.print_type(ty),
1582                         GenericArg::Const(ct) => s.print_anon_const(&ct.value),
1583                     }
1584                 });
1585             }
1586
1587             // FIXME(eddyb): this would leak into error messages (e.g.,
1588             // "non-exhaustive patterns: `Some::<..>(_)` not covered").
1589             if infer_args && false {
1590                 start_or_comma(self);
1591                 self.s.word("..");
1592             }
1593
1594             for binding in generic_args.bindings.iter() {
1595                 start_or_comma(self);
1596                 self.print_ident(binding.ident);
1597                 self.s.space();
1598                 match generic_args.bindings[0].kind {
1599                     hir::TypeBindingKind::Equality { ref ty } => {
1600                         self.word_space("=");
1601                         self.print_type(ty);
1602                     }
1603                     hir::TypeBindingKind::Constraint { ref bounds } => {
1604                         self.print_bounds(":", bounds);
1605                     }
1606                 }
1607             }
1608
1609             if !empty.get() {
1610                 self.s.word(">")
1611             }
1612         }
1613     }
1614
1615     pub fn print_pat(&mut self, pat: &hir::Pat) {
1616         self.maybe_print_comment(pat.span.lo());
1617         self.ann.pre(self, AnnNode::Pat(pat));
1618         // Pat isn't normalized, but the beauty of it
1619         // is that it doesn't matter
1620         match pat.kind {
1621             PatKind::Wild => self.s.word("_"),
1622             PatKind::Binding(binding_mode, _, ident, ref sub) => {
1623                 match binding_mode {
1624                     hir::BindingAnnotation::Ref => {
1625                         self.word_nbsp("ref");
1626                         self.print_mutability(hir::MutImmutable);
1627                     }
1628                     hir::BindingAnnotation::RefMut => {
1629                         self.word_nbsp("ref");
1630                         self.print_mutability(hir::MutMutable);
1631                     }
1632                     hir::BindingAnnotation::Unannotated => {}
1633                     hir::BindingAnnotation::Mutable => {
1634                         self.word_nbsp("mut");
1635                     }
1636                 }
1637                 self.print_ident(ident);
1638                 if let Some(ref p) = *sub {
1639                     self.s.word("@");
1640                     self.print_pat(&p);
1641                 }
1642             }
1643             PatKind::TupleStruct(ref qpath, ref elts, ddpos) => {
1644                 self.print_qpath(qpath, true);
1645                 self.popen();
1646                 if let Some(ddpos) = ddpos {
1647                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p));
1648                     if ddpos != 0 {
1649                         self.word_space(",");
1650                     }
1651                     self.s.word("..");
1652                     if ddpos != elts.len() {
1653                         self.s.word(",");
1654                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p));
1655                     }
1656                 } else {
1657                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p));
1658                 }
1659                 self.pclose();
1660             }
1661             PatKind::Path(ref qpath) => {
1662                 self.print_qpath(qpath, true);
1663             }
1664             PatKind::Struct(ref qpath, ref fields, etc) => {
1665                 self.print_qpath(qpath, true);
1666                 self.nbsp();
1667                 self.word_space("{");
1668                 self.commasep_cmnt(Consistent,
1669                                    &fields[..],
1670                                    |s, f| {
1671                                        s.cbox(INDENT_UNIT);
1672                                        if !f.is_shorthand {
1673                                            s.print_ident(f.ident);
1674                                            s.word_nbsp(":");
1675                                        }
1676                                        s.print_pat(&f.pat);
1677                                        s.end()
1678                                    },
1679                                    |f| f.pat.span);
1680                 if etc {
1681                     if !fields.is_empty() {
1682                         self.word_space(",");
1683                     }
1684                     self.s.word("..");
1685                 }
1686                 self.s.space();
1687                 self.s.word("}");
1688             }
1689             PatKind::Or(ref pats) => {
1690                 self.strsep("|", true, Inconsistent, &pats[..], |s, p| s.print_pat(&p));
1691             }
1692             PatKind::Tuple(ref elts, ddpos) => {
1693                 self.popen();
1694                 if let Some(ddpos) = ddpos {
1695                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p));
1696                     if ddpos != 0 {
1697                         self.word_space(",");
1698                     }
1699                     self.s.word("..");
1700                     if ddpos != elts.len() {
1701                         self.s.word(",");
1702                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p));
1703                     }
1704                 } else {
1705                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p));
1706                     if elts.len() == 1 {
1707                         self.s.word(",");
1708                     }
1709                 }
1710                 self.pclose();
1711             }
1712             PatKind::Box(ref inner) => {
1713                 let is_range_inner = match inner.kind {
1714                     PatKind::Range(..) => true,
1715                     _ => false,
1716                 };
1717                 self.s.word("box ");
1718                 if is_range_inner {
1719                     self.popen();
1720                 }
1721                 self.print_pat(&inner);
1722                 if is_range_inner {
1723                     self.pclose();
1724                 }
1725             }
1726             PatKind::Ref(ref inner, mutbl) => {
1727                 let is_range_inner = match inner.kind {
1728                     PatKind::Range(..) => true,
1729                     _ => false,
1730                 };
1731                 self.s.word("&");
1732                 if mutbl == hir::MutMutable {
1733                     self.s.word("mut ");
1734                 }
1735                 if is_range_inner {
1736                     self.popen();
1737                 }
1738                 self.print_pat(&inner);
1739                 if is_range_inner {
1740                     self.pclose();
1741                 }
1742             }
1743             PatKind::Lit(ref e) => self.print_expr(&e),
1744             PatKind::Range(ref begin, ref end, ref end_kind) => {
1745                 self.print_expr(&begin);
1746                 self.s.space();
1747                 match *end_kind {
1748                     RangeEnd::Included => self.s.word("..."),
1749                     RangeEnd::Excluded => self.s.word(".."),
1750                 }
1751                 self.print_expr(&end);
1752             }
1753             PatKind::Slice(ref before, ref slice, ref after) => {
1754                 self.s.word("[");
1755                 self.commasep(Inconsistent, &before[..], |s, p| s.print_pat(&p));
1756                 if let Some(ref p) = *slice {
1757                     if !before.is_empty() {
1758                         self.word_space(",");
1759                     }
1760                     if let PatKind::Wild = p.kind {
1761                         // Print nothing.
1762                     } else {
1763                         self.print_pat(&p);
1764                     }
1765                     self.s.word("..");
1766                     if !after.is_empty() {
1767                         self.word_space(",");
1768                     }
1769                 }
1770                 self.commasep(Inconsistent, &after[..], |s, p| s.print_pat(&p));
1771                 self.s.word("]");
1772             }
1773         }
1774         self.ann.post(self, AnnNode::Pat(pat))
1775     }
1776
1777     pub fn print_param(&mut self, arg: &hir::Param) {
1778         self.print_outer_attributes(&arg.attrs);
1779         self.print_pat(&arg.pat);
1780     }
1781
1782     pub fn print_arm(&mut self, arm: &hir::Arm) {
1783         // I have no idea why this check is necessary, but here it
1784         // is :(
1785         if arm.attrs.is_empty() {
1786             self.s.space();
1787         }
1788         self.cbox(INDENT_UNIT);
1789         self.ann.pre(self, AnnNode::Arm(arm));
1790         self.ibox(0);
1791         self.print_outer_attributes(&arm.attrs);
1792         self.print_pat(&arm.pat);
1793         self.s.space();
1794         if let Some(ref g) = arm.guard {
1795             match g {
1796                 hir::Guard::If(e) => {
1797                     self.word_space("if");
1798                     self.print_expr(&e);
1799                     self.s.space();
1800                 }
1801             }
1802         }
1803         self.word_space("=>");
1804
1805         match arm.body.kind {
1806             hir::ExprKind::Block(ref blk, opt_label) => {
1807                 if let Some(label) = opt_label {
1808                     self.print_ident(label.ident);
1809                     self.word_space(":");
1810                 }
1811                 // the block will close the pattern's ibox
1812                 self.print_block_unclosed(&blk);
1813
1814                 // If it is a user-provided unsafe block, print a comma after it
1815                 if let hir::UnsafeBlock(hir::UserProvided) = blk.rules {
1816                     self.s.word(",");
1817                 }
1818             }
1819             _ => {
1820                 self.end(); // close the ibox for the pattern
1821                 self.print_expr(&arm.body);
1822                 self.s.word(",");
1823             }
1824         }
1825         self.ann.post(self, AnnNode::Arm(arm));
1826         self.end() // close enclosing cbox
1827     }
1828
1829     pub fn print_fn(&mut self,
1830                     decl: &hir::FnDecl,
1831                     header: hir::FnHeader,
1832                     name: Option<ast::Name>,
1833                     generics: &hir::Generics,
1834                     vis: &hir::Visibility,
1835                     arg_names: &[ast::Ident],
1836                     body_id: Option<hir::BodyId>)
1837                     {
1838         self.print_fn_header_info(header, vis);
1839
1840         if let Some(name) = name {
1841             self.nbsp();
1842             self.print_name(name);
1843         }
1844         self.print_generic_params(&generics.params);
1845
1846         self.popen();
1847         let mut i = 0;
1848         // Make sure we aren't supplied *both* `arg_names` and `body_id`.
1849         assert!(arg_names.is_empty() || body_id.is_none());
1850         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
1851             s.ibox(INDENT_UNIT);
1852             if let Some(arg_name) = arg_names.get(i) {
1853                 s.s.word(arg_name.as_str().to_string());
1854                 s.s.word(":");
1855                 s.s.space();
1856             } else if let Some(body_id) = body_id {
1857                 s.ann.nested(s, Nested::BodyParamPat(body_id, i));
1858                 s.s.word(":");
1859                 s.s.space();
1860             }
1861             i += 1;
1862             s.print_type(ty);
1863             s.end()
1864         });
1865         if decl.c_variadic {
1866             self.s.word(", ...");
1867         }
1868         self.pclose();
1869
1870         self.print_fn_output(decl);
1871         self.print_where_clause(&generics.where_clause)
1872     }
1873
1874     fn print_closure_params(&mut self, decl: &hir::FnDecl, body_id: hir::BodyId) {
1875         self.s.word("|");
1876         let mut i = 0;
1877         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
1878             s.ibox(INDENT_UNIT);
1879
1880             s.ann.nested(s, Nested::BodyParamPat(body_id, i));
1881             i += 1;
1882
1883             if let hir::TyKind::Infer = ty.kind {
1884                 // Print nothing.
1885             } else {
1886                 s.s.word(":");
1887                 s.s.space();
1888                 s.print_type(ty);
1889             }
1890             s.end();
1891         });
1892         self.s.word("|");
1893
1894         if let hir::DefaultReturn(..) = decl.output {
1895             return;
1896         }
1897
1898         self.space_if_not_bol();
1899         self.word_space("->");
1900         match decl.output {
1901             hir::Return(ref ty) => {
1902                 self.print_type(&ty);
1903                 self.maybe_print_comment(ty.span.lo())
1904             }
1905             hir::DefaultReturn(..) => unreachable!(),
1906         }
1907     }
1908
1909     pub fn print_capture_clause(&mut self, capture_clause: hir::CaptureClause) {
1910         match capture_clause {
1911             hir::CaptureByValue => self.word_space("move"),
1912             hir::CaptureByRef => {},
1913         }
1914     }
1915
1916     pub fn print_bounds<'b>(
1917         &mut self,
1918         prefix: &'static str,
1919         bounds: impl IntoIterator<Item = &'b hir::GenericBound>,
1920     ) {
1921         let mut first = true;
1922         for bound in bounds {
1923             if first {
1924                 self.s.word(prefix);
1925             }
1926             if !(first && prefix.is_empty()) {
1927                 self.nbsp();
1928             }
1929             if first {
1930                 first = false;
1931             } else {
1932                 self.word_space("+");
1933             }
1934
1935             match bound {
1936                 GenericBound::Trait(tref, modifier) => {
1937                     if modifier == &TraitBoundModifier::Maybe {
1938                         self.s.word("?");
1939                     }
1940                     self.print_poly_trait_ref(tref);
1941                 }
1942                 GenericBound::Outlives(lt) => {
1943                     self.print_lifetime(lt);
1944                 }
1945             }
1946         }
1947     }
1948
1949     pub fn print_generic_params(&mut self, generic_params: &[GenericParam]) {
1950         if !generic_params.is_empty() {
1951             self.s.word("<");
1952
1953             self.commasep(Inconsistent, generic_params, |s, param| {
1954                 s.print_generic_param(param)
1955             });
1956
1957             self.s.word(">");
1958         }
1959     }
1960
1961     pub fn print_generic_param(&mut self, param: &GenericParam) {
1962         if let GenericParamKind::Const { .. } = param.kind {
1963             self.word_space("const");
1964         }
1965
1966         self.print_ident(param.name.ident());
1967
1968         match param.kind {
1969             GenericParamKind::Lifetime { .. } => {
1970                 let mut sep = ":";
1971                 for bound in &param.bounds {
1972                     match bound {
1973                         GenericBound::Outlives(lt) => {
1974                             self.s.word(sep);
1975                             self.print_lifetime(lt);
1976                             sep = "+";
1977                         }
1978                         _ => bug!(),
1979                     }
1980                 }
1981             }
1982             GenericParamKind::Type { ref default, .. } => {
1983                 self.print_bounds(":", &param.bounds);
1984                 match default {
1985                     Some(default) => {
1986                         self.s.space();
1987                         self.word_space("=");
1988                         self.print_type(&default)
1989                     }
1990                     _ => {}
1991                 }
1992             }
1993             GenericParamKind::Const { ref ty } => {
1994                 self.word_space(":");
1995                 self.print_type(ty)
1996             }
1997         }
1998     }
1999
2000     pub fn print_lifetime(&mut self, lifetime: &hir::Lifetime) {
2001         self.print_ident(lifetime.name.ident())
2002     }
2003
2004     pub fn print_where_clause(&mut self, where_clause: &hir::WhereClause) {
2005         if where_clause.predicates.is_empty() {
2006             return;
2007         }
2008
2009         self.s.space();
2010         self.word_space("where");
2011
2012         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2013             if i != 0 {
2014                 self.word_space(",");
2015             }
2016
2017             match predicate {
2018                 &hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
2019                     ref bound_generic_params,
2020                     ref bounded_ty,
2021                     ref bounds,
2022                     ..
2023                 }) => {
2024                     self.print_formal_generic_params(bound_generic_params);
2025                     self.print_type(&bounded_ty);
2026                     self.print_bounds(":", bounds);
2027                 }
2028                 &hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate{ref lifetime,
2029                                                                                 ref bounds,
2030                                                                                 ..}) => {
2031                     self.print_lifetime(lifetime);
2032                     self.s.word(":");
2033
2034                     for (i, bound) in bounds.iter().enumerate() {
2035                         match bound {
2036                             GenericBound::Outlives(lt) => {
2037                                 self.print_lifetime(lt);
2038                             }
2039                             _ => bug!(),
2040                         }
2041
2042                         if i != 0 {
2043                             self.s.word(":");
2044                         }
2045                     }
2046                 }
2047                 &hir::WherePredicate::EqPredicate(hir::WhereEqPredicate{ref lhs_ty,
2048                                                                         ref rhs_ty,
2049                                                                         ..}) => {
2050                     self.print_type(lhs_ty);
2051                     self.s.space();
2052                     self.word_space("=");
2053                     self.print_type(rhs_ty);
2054                 }
2055             }
2056         }
2057     }
2058
2059     pub fn print_mutability(&mut self, mutbl: hir::Mutability) {
2060         match mutbl {
2061             hir::MutMutable => self.word_nbsp("mut"),
2062             hir::MutImmutable => {},
2063         }
2064     }
2065
2066     pub fn print_mt(&mut self, mt: &hir::MutTy) {
2067         self.print_mutability(mt.mutbl);
2068         self.print_type(&mt.ty)
2069     }
2070
2071     pub fn print_fn_output(&mut self, decl: &hir::FnDecl) {
2072         if let hir::DefaultReturn(..) = decl.output {
2073             return;
2074         }
2075
2076         self.space_if_not_bol();
2077         self.ibox(INDENT_UNIT);
2078         self.word_space("->");
2079         match decl.output {
2080             hir::DefaultReturn(..) => unreachable!(),
2081             hir::Return(ref ty) => self.print_type(&ty),
2082         }
2083         self.end();
2084
2085         match decl.output {
2086             hir::Return(ref output) => self.maybe_print_comment(output.span.lo()),
2087             _ => {},
2088         }
2089     }
2090
2091     pub fn print_ty_fn(&mut self,
2092                        abi: Abi,
2093                        unsafety: hir::Unsafety,
2094                        decl: &hir::FnDecl,
2095                        name: Option<ast::Name>,
2096                        generic_params: &[hir::GenericParam],
2097                        arg_names: &[ast::Ident])
2098                        {
2099         self.ibox(INDENT_UNIT);
2100         if !generic_params.is_empty() {
2101             self.s.word("for");
2102             self.print_generic_params(generic_params);
2103         }
2104         let generics = hir::Generics {
2105             params: hir::HirVec::new(),
2106             where_clause: hir::WhereClause {
2107                 predicates: hir::HirVec::new(),
2108                 span: syntax_pos::DUMMY_SP,
2109             },
2110             span: syntax_pos::DUMMY_SP,
2111         };
2112         self.print_fn(decl,
2113                       hir::FnHeader {
2114                           unsafety,
2115                           abi,
2116                           constness: hir::Constness::NotConst,
2117                           asyncness: hir::IsAsync::NotAsync,
2118                       },
2119                       name,
2120                       &generics,
2121                       &Spanned { span: syntax_pos::DUMMY_SP,
2122                                  node: hir::VisibilityKind::Inherited },
2123                       arg_names,
2124                       None);
2125         self.end();
2126     }
2127
2128     pub fn maybe_print_trailing_comment(&mut self,
2129                                         span: syntax_pos::Span,
2130                                         next_pos: Option<BytePos>)
2131                                         {
2132         if let Some(cmnts) = self.comments() {
2133             if let Some(cmnt) = cmnts.trailing_comment(span, next_pos) {
2134                 self.print_comment(&cmnt);
2135             }
2136         }
2137     }
2138
2139     pub fn print_remaining_comments(&mut self) {
2140         // If there aren't any remaining comments, then we need to manually
2141         // make sure there is a line break at the end.
2142         if self.next_comment().is_none() {
2143             self.s.hardbreak();
2144         }
2145         while let Some(ref cmnt) = self.next_comment() {
2146             self.print_comment(cmnt)
2147         }
2148     }
2149
2150     pub fn print_opt_abi_and_extern_if_nondefault(&mut self,
2151                                                   opt_abi: Option<Abi>)
2152                                                   {
2153         match opt_abi {
2154             Some(Abi::Rust) => {},
2155             Some(abi) => {
2156                 self.word_nbsp("extern");
2157                 self.word_nbsp(abi.to_string())
2158             }
2159             None => {},
2160         }
2161     }
2162
2163     pub fn print_extern_opt_abi(&mut self, opt_abi: Option<Abi>) {
2164         match opt_abi {
2165             Some(abi) => {
2166                 self.word_nbsp("extern");
2167                 self.word_nbsp(abi.to_string())
2168             }
2169             None => {},
2170         }
2171     }
2172
2173     pub fn print_fn_header_info(&mut self,
2174                                 header: hir::FnHeader,
2175                                 vis: &hir::Visibility)
2176                                 {
2177         self.s.word(visibility_qualified(vis, ""));
2178
2179         match header.constness {
2180             hir::Constness::NotConst => {}
2181             hir::Constness::Const => self.word_nbsp("const"),
2182         }
2183
2184         match header.asyncness {
2185             hir::IsAsync::NotAsync => {}
2186             hir::IsAsync::Async => self.word_nbsp("async"),
2187         }
2188
2189         self.print_unsafety(header.unsafety);
2190
2191         if header.abi != Abi::Rust {
2192             self.word_nbsp("extern");
2193             self.word_nbsp(header.abi.to_string());
2194         }
2195
2196         self.s.word("fn")
2197     }
2198
2199     pub fn print_unsafety(&mut self, s: hir::Unsafety) {
2200         match s {
2201             hir::Unsafety::Normal => {}
2202             hir::Unsafety::Unsafe => self.word_nbsp("unsafe"),
2203         }
2204     }
2205
2206     pub fn print_is_auto(&mut self, s: hir::IsAuto) {
2207         match s {
2208             hir::IsAuto::Yes => self.word_nbsp("auto"),
2209             hir::IsAuto::No => {},
2210         }
2211     }
2212 }
2213
2214 /// Does this expression require a semicolon to be treated
2215 /// as a statement? The negation of this: 'can this expression
2216 /// be used as a statement without a semicolon' -- is used
2217 /// as an early-bail-out in the parser so that, for instance,
2218 ///     if true {...} else {...}
2219 ///      |x| 5
2220 /// isn't parsed as (if true {...} else {...} | x) | 5
2221 //
2222 // Duplicated from `parse::classify`, but adapted for the HIR.
2223 fn expr_requires_semi_to_be_stmt(e: &hir::Expr) -> bool {
2224     match e.kind {
2225         hir::ExprKind::Match(..) |
2226         hir::ExprKind::Block(..) |
2227         hir::ExprKind::Loop(..) => false,
2228         _ => true,
2229     }
2230 }
2231
2232 /// This statement requires a semicolon after it.
2233 /// note that in one case (stmt_semi), we've already
2234 /// seen the semicolon, and thus don't need another.
2235 fn stmt_ends_with_semi(stmt: &hir::StmtKind) -> bool {
2236     match *stmt {
2237         hir::StmtKind::Local(_) => true,
2238         hir::StmtKind::Item(_) => false,
2239         hir::StmtKind::Expr(ref e) => expr_requires_semi_to_be_stmt(&e),
2240         hir::StmtKind::Semi(..) => false,
2241     }
2242 }
2243
2244 fn bin_op_to_assoc_op(op: hir::BinOpKind) -> AssocOp {
2245     use crate::hir::BinOpKind::*;
2246     match op {
2247         Add => AssocOp::Add,
2248         Sub => AssocOp::Subtract,
2249         Mul => AssocOp::Multiply,
2250         Div => AssocOp::Divide,
2251         Rem => AssocOp::Modulus,
2252
2253         And => AssocOp::LAnd,
2254         Or => AssocOp::LOr,
2255
2256         BitXor => AssocOp::BitXor,
2257         BitAnd => AssocOp::BitAnd,
2258         BitOr => AssocOp::BitOr,
2259         Shl => AssocOp::ShiftLeft,
2260         Shr => AssocOp::ShiftRight,
2261
2262         Eq => AssocOp::Equal,
2263         Lt => AssocOp::Less,
2264         Le => AssocOp::LessEqual,
2265         Ne => AssocOp::NotEqual,
2266         Ge => AssocOp::GreaterEqual,
2267         Gt => AssocOp::Greater,
2268     }
2269 }
2270
2271 /// Expressions that syntactically contain an "exterior" struct literal, i.e., not surrounded by any
2272 /// parens or other delimiters, e.g., `X { y: 1 }`, `X { y: 1 }.method()`, `foo == X { y: 1 }` and
2273 /// `X { y: 1 } == foo` all do, but `(X { y: 1 }) == foo` does not.
2274 fn contains_exterior_struct_lit(value: &hir::Expr) -> bool {
2275     match value.kind {
2276         hir::ExprKind::Struct(..) => true,
2277
2278         hir::ExprKind::Assign(ref lhs, ref rhs) |
2279         hir::ExprKind::AssignOp(_, ref lhs, ref rhs) |
2280         hir::ExprKind::Binary(_, ref lhs, ref rhs) => {
2281             // `X { y: 1 } + X { y: 2 }`
2282             contains_exterior_struct_lit(&lhs) || contains_exterior_struct_lit(&rhs)
2283         }
2284         hir::ExprKind::Unary(_, ref x) |
2285         hir::ExprKind::Cast(ref x, _) |
2286         hir::ExprKind::Type(ref x, _) |
2287         hir::ExprKind::Field(ref x, _) |
2288         hir::ExprKind::Index(ref x, _) => {
2289             // `&X { y: 1 }, X { y: 1 }.y`
2290             contains_exterior_struct_lit(&x)
2291         }
2292
2293         hir::ExprKind::MethodCall(.., ref exprs) => {
2294             // `X { y: 1 }.bar(...)`
2295             contains_exterior_struct_lit(&exprs[0])
2296         }
2297
2298         _ => false,
2299     }
2300 }