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::parse::lexer::comments;
   6 use syntax::print::pp::{self, Breaks};
   7 use syntax::print::pp::Breaks::{Consistent, Inconsistent};
   8 use syntax::print::pprust::PrintState;
   9 use syntax::ptr::P;
  10 use syntax::symbol::keywords;
  11 use syntax::util::parser::{self, AssocOp, Fixity};
  12 use syntax_pos::{self, BytePos, FileName};
  13
  14 use crate::hir;
  15 use crate::hir::{PatKind, GenericBound, TraitBoundModifier, RangeEnd};
  16 use crate::hir::{GenericParam, GenericParamKind, GenericArg};
  17
  18 use std::borrow::Cow;
  19 use std::cell::Cell;
  20 use std::io::{self, Write, Read};
  21 use std::iter::Peekable;
  22 use std::vec;
  23
  24 pub enum AnnNode<'a> {
  25     Name(&'a ast::Name),
  26     Block(&'a hir::Block),
  27     Item(&'a hir::Item),
  28     SubItem(ast::NodeId),
  29     Expr(&'a hir::Expr),
  30     Pat(&'a hir::Pat),
  31 }
  32
  33 pub enum Nested {
  34     Item(hir::ItemId),
  35     TraitItem(hir::TraitItemId),
  36     ImplItem(hir::ImplItemId),
  37     Body(hir::BodyId),
  38     BodyArgPat(hir::BodyId, usize)
  39 }
  40
  41 pub trait PpAnn {
  42     fn nested(&self, _state: &mut State<'_>, _nested: Nested) -> io::Result<()> {
  43         Ok(())
  44     }
  45     fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) -> io::Result<()> {
  46         Ok(())
  47     }
  48     fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) -> io::Result<()> {
  49         Ok(())
  50     }
  51     fn try_fetch_item(&self, _: ast::NodeId) -> Option<&hir::Item> {
  52         None
  53     }
  54 }
  55
  56 pub struct NoAnn;
  57 impl PpAnn for NoAnn {}
  58 pub const NO_ANN: &dyn PpAnn = &NoAnn;
  59
  60 impl PpAnn for hir::Crate {
  61     fn try_fetch_item(&self, item: ast::NodeId) -> Option<&hir::Item> {
  62         Some(self.item(item))
  63     }
  64     fn nested(&self, state: &mut State<'_>, nested: Nested) -> io::Result<()> {
  65         match nested {
  66             Nested::Item(id) => state.print_item(self.item(id.id)),
  67             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
  68             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
  69             Nested::Body(id) => state.print_expr(&self.body(id).value),
  70             Nested::BodyArgPat(id, i) => state.print_pat(&self.body(id).arguments[i].pat)
  71         }
  72     }
  73 }
  74
  75 pub struct State<'a> {
  76     pub s: pp::Printer<'a>,
  77     cm: Option<&'a SourceMap>,
  78     comments: Option<Vec<comments::Comment>>,
  79     literals: Peekable<vec::IntoIter<comments::Literal>>,
  80     cur_cmnt: usize,
  81     boxes: Vec<pp::Breaks>,
  82     ann: &'a (dyn PpAnn + 'a),
  83 }
  84
  85 impl<'a> PrintState<'a> for State<'a> {
  86     fn writer(&mut self) -> &mut pp::Printer<'a> {
  87         &mut self.s
  88     }
  89
  90     fn boxes(&mut self) -> &mut Vec<pp::Breaks> {
  91         &mut self.boxes
  92     }
  93
  94     fn comments(&mut self) -> &mut Option<Vec<comments::Comment>> {
  95         &mut self.comments
  96     }
  97
  98     fn cur_cmnt(&mut self) -> &mut usize {
  99         &mut self.cur_cmnt
 100     }
 101
 102     fn cur_lit(&mut self) -> Option<&comments::Literal> {
 103         self.literals.peek()
 104     }
 105
 106     fn bump_lit(&mut self) -> Option<comments::Literal> {
 107         self.literals.next()
 108     }
 109 }
 110
 111 #[allow(non_upper_case_globals)]
 112 pub const indent_unit: usize = 4;
 113
 114 #[allow(non_upper_case_globals)]
 115 pub const default_columns: usize = 78;
 116
 117
 118 /// Requires you to pass an input filename and reader so that
 119 /// it can scan the input text for comments and literals to
 120 /// copy forward.
 121 pub fn print_crate<'a>(cm: &'a SourceMap,
 122                        sess: &ParseSess,
 123                        krate: &hir::Crate,
 124                        filename: FileName,
 125                        input: &mut dyn Read,
 126                        out: Box<dyn Write + 'a>,
 127                        ann: &'a dyn PpAnn,
 128                        is_expanded: bool)
 129                        -> io::Result<()> {
 130     let mut s = State::new_from_input(cm, sess, filename, input, out, ann, is_expanded);
 131
 132     // When printing the AST, we sometimes need to inject `#[no_std]` here.
 133     // Since you can't compile the HIR, it's not necessary.
 134
 135     s.print_mod(&krate.module, &krate.attrs)?;
 136     s.print_remaining_comments()?;
 137     s.s.eof()
 138 }
 139
 140 impl<'a> State<'a> {
 141     pub fn new_from_input(cm: &'a SourceMap,
 142                           sess: &ParseSess,
 143                           filename: FileName,
 144                           input: &mut dyn Read,
 145                           out: Box<dyn Write + 'a>,
 146                           ann: &'a dyn PpAnn,
 147                           is_expanded: bool)
 148                           -> State<'a> {
 149         let (cmnts, lits) = comments::gather_comments_and_literals(sess, filename, input);
 150
 151         State::new(cm,
 152                    out,
 153                    ann,
 154                    Some(cmnts),
 155                    // If the code is post expansion, don't use the table of
 156                    // literals, since it doesn't correspond with the literals
 157                    // in the AST anymore.
 158                    if is_expanded {
 159                        None
 160                    } else {
 161                        Some(lits)
 162                    })
 163     }
 164
 165     pub fn new(cm: &'a SourceMap,
 166                out: Box<dyn Write + 'a>,
 167                ann: &'a dyn PpAnn,
 168                comments: Option<Vec<comments::Comment>>,
 169                literals: Option<Vec<comments::Literal>>)
 170                -> State<'a> {
 171         State {
 172             s: pp::mk_printer(out, default_columns),
 173             cm: Some(cm),
 174             comments,
 175             literals: literals.unwrap_or_default().into_iter().peekable(),
 176             cur_cmnt: 0,
 177             boxes: Vec::new(),
 178             ann,
 179         }
 180     }
 181 }
 182
 183 pub fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
 184     where F: FnOnce(&mut State<'_>) -> io::Result<()>
 185 {
 186     let mut wr = Vec::new();
 187     {
 188         let mut printer = State {
 189             s: pp::mk_printer(Box::new(&mut wr), default_columns),
 190             cm: None,
 191             comments: None,
 192             literals: vec![].into_iter().peekable(),
 193             cur_cmnt: 0,
 194             boxes: Vec::new(),
 195             ann,
 196         };
 197         f(&mut printer).unwrap();
 198         printer.s.eof().unwrap();
 199     }
 200     String::from_utf8(wr).unwrap()
 201 }
 202
 203 pub fn visibility_qualified<S: Into<Cow<'static, str>>>(vis: &hir::Visibility, w: S) -> String {
 204     to_string(NO_ANN, |s| {
 205         s.print_visibility(vis)?;
 206         s.s.word(w)
 207     })
 208 }
 209
 210 impl<'a> State<'a> {
 211     pub fn cbox(&mut self, u: usize) -> io::Result<()> {
 212         self.boxes.push(pp::Breaks::Consistent);
 213         self.s.cbox(u)
 214     }
 215
 216     pub fn nbsp(&mut self) -> io::Result<()> {
 217         self.s.word(" ")
 218     }
 219
 220     pub fn word_nbsp<S: Into<Cow<'static, str>>>(&mut self, w: S) -> io::Result<()> {
 221         self.s.word(w)?;
 222         self.nbsp()
 223     }
 224
 225     pub fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) -> io::Result<()> {
 226         let w = w.into();
 227         // outer-box is consistent
 228         self.cbox(indent_unit)?;
 229         // head-box is inconsistent
 230         self.ibox(w.len() + 1)?;
 231         // keyword that starts the head
 232         if !w.is_empty() {
 233             self.word_nbsp(w)?;
 234         }
 235         Ok(())
 236     }
 237
 238     pub fn bopen(&mut self) -> io::Result<()> {
 239         self.s.word("{")?;
 240         self.end() // close the head-box
 241     }
 242
 243     pub fn bclose_(&mut self, span: syntax_pos::Span, indented: usize) -> io::Result<()> {
 244         self.bclose_maybe_open(span, indented, true)
 245     }
 246
 247     pub fn bclose_maybe_open(&mut self,
 248                              span: syntax_pos::Span,
 249                              indented: usize,
 250                              close_box: bool)
 251                              -> io::Result<()> {
 252         self.maybe_print_comment(span.hi())?;
 253         self.break_offset_if_not_bol(1, -(indented as isize))?;
 254         self.s.word("}")?;
 255         if close_box {
 256             self.end()?; // close the outer-box
 257         }
 258         Ok(())
 259     }
 260
 261     pub fn bclose(&mut self, span: syntax_pos::Span) -> io::Result<()> {
 262         self.bclose_(span, indent_unit)
 263     }
 264
 265     pub fn in_cbox(&self) -> bool {
 266         match self.boxes.last() {
 267             Some(&last_box) => last_box == pp::Breaks::Consistent,
 268             None => false,
 269         }
 270     }
 271
 272     pub fn space_if_not_bol(&mut self) -> io::Result<()> {
 273         if !self.is_bol() {
 274             self.s.space()?;
 275         }
 276         Ok(())
 277     }
 278
 279     pub fn break_offset_if_not_bol(&mut self, n: usize, off: isize) -> io::Result<()> {
 280         if !self.is_bol() {
 281             self.s.break_offset(n, off)
 282         } else {
 283             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 284                 // We do something pretty sketchy here: tuck the nonzero
 285                 // offset-adjustment we were going to deposit along with the
 286                 // break into the previous hardbreak.
 287                 self.s.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 288             }
 289             Ok(())
 290         }
 291     }
 292
 293     // Synthesizes a comment that was not textually present in the original source
 294     // file.
 295     pub fn synth_comment(&mut self, text: String) -> io::Result<()> {
 296         self.s.word("/*")?;
 297         self.s.space()?;
 298         self.s.word(text)?;
 299         self.s.space()?;
 300         self.s.word("*/")
 301     }
 302
 303     pub fn commasep_cmnt<T, F, G>(&mut self,
 304                                   b: Breaks,
 305                                   elts: &[T],
 306                                   mut op: F,
 307                                   mut get_span: G)
 308                                   -> io::Result<()>
 309         where F: FnMut(&mut State<'_>, &T) -> io::Result<()>,
 310               G: FnMut(&T) -> syntax_pos::Span
 311     {
 312         self.rbox(0, b)?;
 313         let len = elts.len();
 314         let mut i = 0;
 315         for elt in elts {
 316             self.maybe_print_comment(get_span(elt).hi())?;
 317             op(self, elt)?;
 318             i += 1;
 319             if i < len {
 320                 self.s.word(",")?;
 321                 self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()))?;
 322                 self.space_if_not_bol()?;
 323             }
 324         }
 325         self.end()
 326     }
 327
 328     pub fn commasep_exprs(&mut self, b: Breaks, exprs: &[hir::Expr]) -> io::Result<()> {
 329         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
 330     }
 331
 332     pub fn print_mod(&mut self, _mod: &hir::Mod, attrs: &[ast::Attribute]) -> io::Result<()> {
 333         self.print_inner_attributes(attrs)?;
 334         for &item_id in &_mod.item_ids {
 335             self.ann.nested(self, Nested::Item(item_id))?;
 336         }
 337         Ok(())
 338     }
 339
 340     pub fn print_foreign_mod(&mut self,
 341                              nmod: &hir::ForeignMod,
 342                              attrs: &[ast::Attribute])
 343                              -> io::Result<()> {
 344         self.print_inner_attributes(attrs)?;
 345         for item in &nmod.items {
 346             self.print_foreign_item(item)?;
 347         }
 348         Ok(())
 349     }
 350
 351     pub fn print_opt_lifetime(&mut self, lifetime: &hir::Lifetime) -> io::Result<()> {
 352         if !lifetime.is_elided() {
 353             self.print_lifetime(lifetime)?;
 354             self.nbsp()?;
 355         }
 356         Ok(())
 357     }
 358
 359     pub fn print_type(&mut self, ty: &hir::Ty) -> io::Result<()> {
 360         self.maybe_print_comment(ty.span.lo())?;
 361         self.ibox(0)?;
 362         match ty.node {
 363             hir::TyKind::Slice(ref ty) => {
 364                 self.s.word("[")?;
 365                 self.print_type(&ty)?;
 366                 self.s.word("]")?;
 367             }
 368             hir::TyKind::Ptr(ref mt) => {
 369                 self.s.word("*")?;
 370                 match mt.mutbl {
 371                     hir::MutMutable => self.word_nbsp("mut")?,
 372                     hir::MutImmutable => self.word_nbsp("const")?,
 373                 }
 374                 self.print_type(&mt.ty)?;
 375             }
 376             hir::TyKind::Rptr(ref lifetime, ref mt) => {
 377                 self.s.word("&")?;
 378                 self.print_opt_lifetime(lifetime)?;
 379                 self.print_mt(mt)?;
 380             }
 381             hir::TyKind::Never => {
 382                 self.s.word("!")?;
 383             },
 384             hir::TyKind::Tup(ref elts) => {
 385                 self.popen()?;
 386                 self.commasep(Inconsistent, &elts[..], |s, ty| s.print_type(&ty))?;
 387                 if elts.len() == 1 {
 388                     self.s.word(",")?;
 389                 }
 390                 self.pclose()?;
 391             }
 392             hir::TyKind::BareFn(ref f) => {
 393                 self.print_ty_fn(f.abi, f.unsafety, &f.decl, None, &f.generic_params,
 394                                  &f.arg_names[..])?;
 395             }
 396             hir::TyKind::Def(..) => {},
 397             hir::TyKind::Path(ref qpath) => {
 398                 self.print_qpath(qpath, false)?
 399             }
 400             hir::TyKind::TraitObject(ref bounds, ref lifetime) => {
 401                 let mut first = true;
 402                 for bound in bounds {
 403                     if first {
 404                         first = false;
 405                     } else {
 406                         self.nbsp()?;
 407                         self.word_space("+")?;
 408                     }
 409                     self.print_poly_trait_ref(bound)?;
 410                 }
 411                 if !lifetime.is_elided() {
 412                     self.nbsp()?;
 413                     self.word_space("+")?;
 414                     self.print_lifetime(lifetime)?;
 415                 }
 416             }
 417             hir::TyKind::Array(ref ty, ref length) => {
 418                 self.s.word("[")?;
 419                 self.print_type(&ty)?;
 420                 self.s.word("; ")?;
 421                 self.print_anon_const(length)?;
 422                 self.s.word("]")?;
 423             }
 424             hir::TyKind::Typeof(ref e) => {
 425                 self.s.word("typeof(")?;
 426                 self.print_anon_const(e)?;
 427                 self.s.word(")")?;
 428             }
 429             hir::TyKind::Infer => {
 430                 self.s.word("_")?;
 431             }
 432             hir::TyKind::Err => {
 433                 self.popen()?;
 434                 self.s.word("/*ERROR*/")?;
 435                 self.pclose()?;
 436             }
 437         }
 438         self.end()
 439     }
 440
 441     pub fn print_foreign_item(&mut self, item: &hir::ForeignItem) -> io::Result<()> {
 442         self.hardbreak_if_not_bol()?;
 443         self.maybe_print_comment(item.span.lo())?;
 444         self.print_outer_attributes(&item.attrs)?;
 445         match item.node {
 446             hir::ForeignItemKind::Fn(ref decl, ref arg_names, ref generics) => {
 447                 self.head("")?;
 448                 self.print_fn(decl,
 449                               hir::FnHeader {
 450                                   unsafety: hir::Unsafety::Normal,
 451                                   constness: hir::Constness::NotConst,
 452                                   abi: Abi::Rust,
 453                                   asyncness: hir::IsAsync::NotAsync,
 454                               },
 455                               Some(item.ident.name),
 456                               generics,
 457                               &item.vis,
 458                               arg_names,
 459                               None)?;
 460                 self.end()?; // end head-ibox
 461                 self.s.word(";")?;
 462                 self.end() // end the outer fn box
 463             }
 464             hir::ForeignItemKind::Static(ref t, m) => {
 465                 self.head(visibility_qualified(&item.vis, "static"))?;
 466                 if m {
 467                     self.word_space("mut")?;
 468                 }
 469                 self.print_ident(item.ident)?;
 470                 self.word_space(":")?;
 471                 self.print_type(&t)?;
 472                 self.s.word(";")?;
 473                 self.end()?; // end the head-ibox
 474                 self.end() // end the outer cbox
 475             }
 476             hir::ForeignItemKind::Type => {
 477                 self.head(visibility_qualified(&item.vis, "type"))?;
 478                 self.print_ident(item.ident)?;
 479                 self.s.word(";")?;
 480                 self.end()?; // end the head-ibox
 481                 self.end() // end the outer cbox
 482             }
 483         }
 484     }
 485
 486     fn print_associated_const(&mut self,
 487                               ident: ast::Ident,
 488                               ty: &hir::Ty,
 489                               default: Option<hir::BodyId>,
 490                               vis: &hir::Visibility)
 491                               -> io::Result<()> {
 492         self.s.word(visibility_qualified(vis, ""))?;
 493         self.word_space("const")?;
 494         self.print_ident(ident)?;
 495         self.word_space(":")?;
 496         self.print_type(ty)?;
 497         if let Some(expr) = default {
 498             self.s.space()?;
 499             self.word_space("=")?;
 500             self.ann.nested(self, Nested::Body(expr))?;
 501         }
 502         self.s.word(";")
 503     }
 504
 505     fn print_associated_type(&mut self,
 506                              ident: ast::Ident,
 507                              bounds: Option<&hir::GenericBounds>,
 508                              ty: Option<&hir::Ty>)
 509                              -> io::Result<()> {
 510         self.word_space("type")?;
 511         self.print_ident(ident)?;
 512         if let Some(bounds) = bounds {
 513             self.print_bounds(":", bounds)?;
 514         }
 515         if let Some(ty) = ty {
 516             self.s.space()?;
 517             self.word_space("=")?;
 518             self.print_type(ty)?;
 519         }
 520         self.s.word(";")
 521     }
 522
 523     /// Pretty-print an item
 524     pub fn print_item(&mut self, item: &hir::Item) -> io::Result<()> {
 525         self.hardbreak_if_not_bol()?;
 526         self.maybe_print_comment(item.span.lo())?;
 527         self.print_outer_attributes(&item.attrs)?;
 528         self.ann.pre(self, AnnNode::Item(item))?;
 529         match item.node {
 530             hir::ItemKind::ExternCrate(orig_name) => {
 531                 self.head(visibility_qualified(&item.vis, "extern crate"))?;
 532                 if let Some(orig_name) = orig_name {
 533                     self.print_name(orig_name)?;
 534                     self.s.space()?;
 535                     self.s.word("as")?;
 536                     self.s.space()?;
 537                 }
 538                 self.print_ident(item.ident)?;
 539                 self.s.word(";")?;
 540                 self.end()?; // end inner head-block
 541                 self.end()?; // end outer head-block
 542             }
 543             hir::ItemKind::Use(ref path, kind) => {
 544                 self.head(visibility_qualified(&item.vis, "use"))?;
 545                 self.print_path(path, false)?;
 546
 547                 match kind {
 548                     hir::UseKind::Single => {
 549                         if path.segments.last().unwrap().ident != item.ident {
 550                             self.s.space()?;
 551                             self.word_space("as")?;
 552                             self.print_ident(item.ident)?;
 553                         }
 554                         self.s.word(";")?;
 555                     }
 556                     hir::UseKind::Glob => self.s.word("::*;")?,
 557                     hir::UseKind::ListStem => self.s.word("::{};")?
 558                 }
 559                 self.end()?; // end inner head-block
 560                 self.end()?; // end outer head-block
 561             }
 562             hir::ItemKind::Static(ref ty, m, expr) => {
 563                 self.head(visibility_qualified(&item.vis, "static"))?;
 564                 if m == hir::MutMutable {
 565                     self.word_space("mut")?;
 566                 }
 567                 self.print_ident(item.ident)?;
 568                 self.word_space(":")?;
 569                 self.print_type(&ty)?;
 570                 self.s.space()?;
 571                 self.end()?; // end the head-ibox
 572
 573                 self.word_space("=")?;
 574                 self.ann.nested(self, Nested::Body(expr))?;
 575                 self.s.word(";")?;
 576                 self.end()?; // end the outer cbox
 577             }
 578             hir::ItemKind::Const(ref ty, expr) => {
 579                 self.head(visibility_qualified(&item.vis, "const"))?;
 580                 self.print_ident(item.ident)?;
 581                 self.word_space(":")?;
 582                 self.print_type(&ty)?;
 583                 self.s.space()?;
 584                 self.end()?; // end the head-ibox
 585
 586                 self.word_space("=")?;
 587                 self.ann.nested(self, Nested::Body(expr))?;
 588                 self.s.word(";")?;
 589                 self.end()?; // end the outer cbox
 590             }
 591             hir::ItemKind::Fn(ref decl, header, ref typarams, body) => {
 592                 self.head("")?;
 593                 self.print_fn(decl,
 594                               header,
 595                               Some(item.ident.name),
 596                               typarams,
 597                               &item.vis,
 598                               &[],
 599                               Some(body))?;
 600                 self.s.word(" ")?;
 601                 self.end()?; // need to close a box
 602                 self.end()?; // need to close a box
 603                 self.ann.nested(self, Nested::Body(body))?;
 604             }
 605             hir::ItemKind::Mod(ref _mod) => {
 606                 self.head(visibility_qualified(&item.vis, "mod"))?;
 607                 self.print_ident(item.ident)?;
 608                 self.nbsp()?;
 609                 self.bopen()?;
 610                 self.print_mod(_mod, &item.attrs)?;
 611                 self.bclose(item.span)?;
 612             }
 613             hir::ItemKind::ForeignMod(ref nmod) => {
 614                 self.head("extern")?;
 615                 self.word_nbsp(nmod.abi.to_string())?;
 616                 self.bopen()?;
 617                 self.print_foreign_mod(nmod, &item.attrs)?;
 618                 self.bclose(item.span)?;
 619             }
 620             hir::ItemKind::GlobalAsm(ref ga) => {
 621                 self.head(visibility_qualified(&item.vis, "global asm"))?;
 622                 self.s.word(ga.asm.as_str().get())?;
 623                 self.end()?
 624             }
 625             hir::ItemKind::Ty(ref ty, ref generics) => {
 626                 self.head(visibility_qualified(&item.vis, "type"))?;
 627                 self.print_ident(item.ident)?;
 628                 self.print_generic_params(&generics.params)?;
 629                 self.end()?; // end the inner ibox
 630
 631                 self.print_where_clause(&generics.where_clause)?;
 632                 self.s.space()?;
 633                 self.word_space("=")?;
 634                 self.print_type(&ty)?;
 635                 self.s.word(";")?;
 636                 self.end()?; // end the outer ibox
 637             }
 638             hir::ItemKind::Existential(ref exist) => {
 639                 self.head(visibility_qualified(&item.vis, "existential type"))?;
 640                 self.print_ident(item.ident)?;
 641                 self.print_generic_params(&exist.generics.params)?;
 642                 self.end()?; // end the inner ibox
 643
 644                 self.print_where_clause(&exist.generics.where_clause)?;
 645                 self.s.space()?;
 646                 self.word_space(":")?;
 647                 let mut real_bounds = Vec::with_capacity(exist.bounds.len());
 648                 for b in exist.bounds.iter() {
 649                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 650                         self.s.space()?;
 651                         self.word_space("for ?")?;
 652                         self.print_trait_ref(&ptr.trait_ref)?;
 653                     } else {
 654                         real_bounds.push(b.clone());
 655                     }
 656                 }
 657                 self.print_bounds(":", &real_bounds[..])?;
 658                 self.s.word(";")?;
 659                 self.end()?; // end the outer ibox
 660             }
 661             hir::ItemKind::Enum(ref enum_definition, ref params) => {
 662                 self.print_enum_def(enum_definition, params, item.ident.name, item.span,
 663                                     &item.vis)?;
 664             }
 665             hir::ItemKind::Struct(ref struct_def, ref generics) => {
 666                 self.head(visibility_qualified(&item.vis, "struct"))?;
 667                 self.print_struct(struct_def, generics, item.ident.name, item.span, true)?;
 668             }
 669             hir::ItemKind::Union(ref struct_def, ref generics) => {
 670                 self.head(visibility_qualified(&item.vis, "union"))?;
 671                 self.print_struct(struct_def, generics, item.ident.name, item.span, true)?;
 672             }
 673             hir::ItemKind::Impl(unsafety,
 674                           polarity,
 675                           defaultness,
 676                           ref generics,
 677                           ref opt_trait,
 678                           ref ty,
 679                           ref impl_items) => {
 680                 self.head("")?;
 681                 self.print_visibility(&item.vis)?;
 682                 self.print_defaultness(defaultness)?;
 683                 self.print_unsafety(unsafety)?;
 684                 self.word_nbsp("impl")?;
 685
 686                 if !generics.params.is_empty() {
 687                     self.print_generic_params(&generics.params)?;
 688                     self.s.space()?;
 689                 }
 690
 691                 if let hir::ImplPolarity::Negative = polarity {
 692                     self.s.word("!")?;
 693                 }
 694
 695                 if let Some(ref t) = opt_trait {
 696                     self.print_trait_ref(t)?;
 697                     self.s.space()?;
 698                     self.word_space("for")?;
 699                 }
 700
 701                 self.print_type(&ty)?;
 702                 self.print_where_clause(&generics.where_clause)?;
 703
 704                 self.s.space()?;
 705                 self.bopen()?;
 706                 self.print_inner_attributes(&item.attrs)?;
 707                 for impl_item in impl_items {
 708                     self.ann.nested(self, Nested::ImplItem(impl_item.id))?;
 709                 }
 710                 self.bclose(item.span)?;
 711             }
 712             hir::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref trait_items) => {
 713                 self.head("")?;
 714                 self.print_visibility(&item.vis)?;
 715                 self.print_is_auto(is_auto)?;
 716                 self.print_unsafety(unsafety)?;
 717                 self.word_nbsp("trait")?;
 718                 self.print_ident(item.ident)?;
 719                 self.print_generic_params(&generics.params)?;
 720                 let mut real_bounds = Vec::with_capacity(bounds.len());
 721                 for b in bounds.iter() {
 722                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 723                         self.s.space()?;
 724                         self.word_space("for ?")?;
 725                         self.print_trait_ref(&ptr.trait_ref)?;
 726                     } else {
 727                         real_bounds.push(b.clone());
 728                     }
 729                 }
 730                 self.print_bounds(":", &real_bounds[..])?;
 731                 self.print_where_clause(&generics.where_clause)?;
 732                 self.s.word(" ")?;
 733                 self.bopen()?;
 734                 for trait_item in trait_items {
 735                     self.ann.nested(self, Nested::TraitItem(trait_item.id))?;
 736                 }
 737                 self.bclose(item.span)?;
 738             }
 739             hir::ItemKind::TraitAlias(ref generics, ref bounds) => {
 740                 self.head("")?;
 741                 self.print_visibility(&item.vis)?;
 742                 self.word_nbsp("trait")?;
 743                 self.print_ident(item.ident)?;
 744                 self.print_generic_params(&generics.params)?;
 745                 let mut real_bounds = Vec::with_capacity(bounds.len());
 746                 // FIXME(durka) this seems to be some quite outdated syntax
 747                 for b in bounds.iter() {
 748                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 749                         self.s.space()?;
 750                         self.word_space("for ?")?;
 751                         self.print_trait_ref(&ptr.trait_ref)?;
 752                     } else {
 753                         real_bounds.push(b.clone());
 754                     }
 755                 }
 756                 self.nbsp()?;
 757                 self.print_bounds("=", &real_bounds[..])?;
 758                 self.print_where_clause(&generics.where_clause)?;
 759                 self.s.word(";")?;
 760             }
 761         }
 762         self.ann.post(self, AnnNode::Item(item))
 763     }
 764
 765     pub fn print_trait_ref(&mut self, t: &hir::TraitRef) -> io::Result<()> {
 766         self.print_path(&t.path, false)
 767     }
 768
 769     fn print_formal_generic_params(
 770         &mut self,
 771         generic_params: &[hir::GenericParam]
 772     ) -> io::Result<()> {
 773         if !generic_params.is_empty() {
 774             self.s.word("for")?;
 775             self.print_generic_params(generic_params)?;
 776             self.nbsp()?;
 777         }
 778         Ok(())
 779     }
 780
 781     fn print_poly_trait_ref(&mut self, t: &hir::PolyTraitRef) -> io::Result<()> {
 782         self.print_formal_generic_params(&t.bound_generic_params)?;
 783         self.print_trait_ref(&t.trait_ref)
 784     }
 785
 786     pub fn print_enum_def(&mut self,
 787                           enum_definition: &hir::EnumDef,
 788                           generics: &hir::Generics,
 789                           name: ast::Name,
 790                           span: syntax_pos::Span,
 791                           visibility: &hir::Visibility)
 792                           -> io::Result<()> {
 793         self.head(visibility_qualified(visibility, "enum"))?;
 794         self.print_name(name)?;
 795         self.print_generic_params(&generics.params)?;
 796         self.print_where_clause(&generics.where_clause)?;
 797         self.s.space()?;
 798         self.print_variants(&enum_definition.variants, span)
 799     }
 800
 801     pub fn print_variants(&mut self,
 802                           variants: &[hir::Variant],
 803                           span: syntax_pos::Span)
 804                           -> io::Result<()> {
 805         self.bopen()?;
 806         for v in variants {
 807             self.space_if_not_bol()?;
 808             self.maybe_print_comment(v.span.lo())?;
 809             self.print_outer_attributes(&v.node.attrs)?;
 810             self.ibox(indent_unit)?;
 811             self.print_variant(v)?;
 812             self.s.word(",")?;
 813             self.end()?;
 814             self.maybe_print_trailing_comment(v.span, None)?;
 815         }
 816         self.bclose(span)
 817     }
 818
 819     pub fn print_visibility(&mut self, vis: &hir::Visibility) -> io::Result<()> {
 820         match vis.node {
 821             hir::VisibilityKind::Public => self.word_nbsp("pub")?,
 822             hir::VisibilityKind::Crate(ast::CrateSugar::JustCrate) => self.word_nbsp("crate")?,
 823             hir::VisibilityKind::Crate(ast::CrateSugar::PubCrate) => self.word_nbsp("pub(crate)")?,
 824             hir::VisibilityKind::Restricted { ref path, .. } => {
 825                 self.s.word("pub(")?;
 826                 if path.segments.len() == 1 &&
 827                    path.segments[0].ident.name == keywords::Super.name() {
 828                     // Special case: `super` can print like `pub(super)`.
 829                     self.s.word("super")?;
 830                 } else {
 831                     // Everything else requires `in` at present.
 832                     self.word_nbsp("in")?;
 833                     self.print_path(path, false)?;
 834                 }
 835                 self.word_nbsp(")")?;
 836             }
 837             hir::VisibilityKind::Inherited => ()
 838         }
 839
 840         Ok(())
 841     }
 842
 843     pub fn print_defaultness(&mut self, defaultness: hir::Defaultness) -> io::Result<()> {
 844         match defaultness {
 845             hir::Defaultness::Default { .. } => self.word_nbsp("default")?,
 846             hir::Defaultness::Final => (),
 847         }
 848         Ok(())
 849     }
 850
 851     pub fn print_struct(&mut self,
 852                         struct_def: &hir::VariantData,
 853                         generics: &hir::Generics,
 854                         name: ast::Name,
 855                         span: syntax_pos::Span,
 856                         print_finalizer: bool)
 857                         -> io::Result<()> {
 858         self.print_name(name)?;
 859         self.print_generic_params(&generics.params)?;
 860         if !struct_def.is_struct() {
 861             if struct_def.is_tuple() {
 862                 self.popen()?;
 863                 self.commasep(Inconsistent, struct_def.fields(), |s, field| {
 864                     s.maybe_print_comment(field.span.lo())?;
 865                     s.print_outer_attributes(&field.attrs)?;
 866                     s.print_visibility(&field.vis)?;
 867                     s.print_type(&field.ty)
 868                 })?;
 869                 self.pclose()?;
 870             }
 871             self.print_where_clause(&generics.where_clause)?;
 872             if print_finalizer {
 873                 self.s.word(";")?;
 874             }
 875             self.end()?;
 876             self.end() // close the outer-box
 877         } else {
 878             self.print_where_clause(&generics.where_clause)?;
 879             self.nbsp()?;
 880             self.bopen()?;
 881             self.hardbreak_if_not_bol()?;
 882
 883             for field in struct_def.fields() {
 884                 self.hardbreak_if_not_bol()?;
 885                 self.maybe_print_comment(field.span.lo())?;
 886                 self.print_outer_attributes(&field.attrs)?;
 887                 self.print_visibility(&field.vis)?;
 888                 self.print_ident(field.ident)?;
 889                 self.word_nbsp(":")?;
 890                 self.print_type(&field.ty)?;
 891                 self.s.word(",")?;
 892             }
 893
 894             self.bclose(span)
 895         }
 896     }
 897
 898     pub fn print_variant(&mut self, v: &hir::Variant) -> io::Result<()> {
 899         self.head("")?;
 900         let generics = hir::Generics::empty();
 901         self.print_struct(&v.node.data, &generics, v.node.ident.name, v.span, false)?;
 902         if let Some(ref d) = v.node.disr_expr {
 903             self.s.space()?;
 904             self.word_space("=")?;
 905             self.print_anon_const(d)?;
 906         }
 907         Ok(())
 908     }
 909     pub fn print_method_sig(&mut self,
 910                             ident: ast::Ident,
 911                             m: &hir::MethodSig,
 912                             generics: &hir::Generics,
 913                             vis: &hir::Visibility,
 914                             arg_names: &[ast::Ident],
 915                             body_id: Option<hir::BodyId>)
 916                             -> io::Result<()> {
 917         self.print_fn(&m.decl,
 918                       m.header,
 919                       Some(ident.name),
 920                       generics,
 921                       vis,
 922                       arg_names,
 923                       body_id)
 924     }
 925
 926     pub fn print_trait_item(&mut self, ti: &hir::TraitItem) -> io::Result<()> {
 927         self.ann.pre(self, AnnNode::SubItem(ti.id))?;
 928         self.hardbreak_if_not_bol()?;
 929         self.maybe_print_comment(ti.span.lo())?;
 930         self.print_outer_attributes(&ti.attrs)?;
 931         match ti.node {
 932             hir::TraitItemKind::Const(ref ty, default) => {
 933                 let vis = Spanned { span: syntax_pos::DUMMY_SP,
 934                                     node: hir::VisibilityKind::Inherited };
 935                 self.print_associated_const(ti.ident, &ty, default, &vis)?;
 936             }
 937             hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Required(ref arg_names)) => {
 938                 let vis = Spanned { span: syntax_pos::DUMMY_SP,
 939                                     node: hir::VisibilityKind::Inherited };
 940                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, arg_names, None)?;
 941                 self.s.word(";")?;
 942             }
 943             hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Provided(body)) => {
 944                 let vis = Spanned { span: syntax_pos::DUMMY_SP,
 945                                     node: hir::VisibilityKind::Inherited };
 946                 self.head("")?;
 947                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, &[], Some(body))?;
 948                 self.nbsp()?;
 949                 self.end()?; // need to close a box
 950                 self.end()?; // need to close a box
 951                 self.ann.nested(self, Nested::Body(body))?;
 952             }
 953             hir::TraitItemKind::Type(ref bounds, ref default) => {
 954                 self.print_associated_type(ti.ident,
 955                                            Some(bounds),
 956                                            default.as_ref().map(|ty| &**ty))?;
 957             }
 958         }
 959         self.ann.post(self, AnnNode::SubItem(ti.id))
 960     }
 961
 962     pub fn print_impl_item(&mut self, ii: &hir::ImplItem) -> io::Result<()> {
 963         self.ann.pre(self, AnnNode::SubItem(ii.id))?;
 964         self.hardbreak_if_not_bol()?;
 965         self.maybe_print_comment(ii.span.lo())?;
 966         self.print_outer_attributes(&ii.attrs)?;
 967         self.print_defaultness(ii.defaultness)?;
 968
 969         match ii.node {
 970             hir::ImplItemKind::Const(ref ty, expr) => {
 971                 self.print_associated_const(ii.ident, &ty, Some(expr), &ii.vis)?;
 972             }
 973             hir::ImplItemKind::Method(ref sig, body) => {
 974                 self.head("")?;
 975                 self.print_method_sig(ii.ident, sig, &ii.generics, &ii.vis, &[], Some(body))?;
 976                 self.nbsp()?;
 977                 self.end()?; // need to close a box
 978                 self.end()?; // need to close a box
 979                 self.ann.nested(self, Nested::Body(body))?;
 980             }
 981             hir::ImplItemKind::Type(ref ty) => {
 982                 self.print_associated_type(ii.ident, None, Some(ty))?;
 983             }
 984             hir::ImplItemKind::Existential(ref bounds) => {
 985                 self.word_space("existential")?;
 986                 self.print_associated_type(ii.ident, Some(bounds), None)?;
 987             }
 988         }
 989         self.ann.post(self, AnnNode::SubItem(ii.id))
 990     }
 991
 992     pub fn print_stmt(&mut self, st: &hir::Stmt) -> io::Result<()> {
 993         self.maybe_print_comment(st.span.lo())?;
 994         match st.node {
 995             hir::StmtKind::Local(ref loc) => {
 996                 self.space_if_not_bol()?;
 997                 self.ibox(indent_unit)?;
 998                 self.word_nbsp("let")?;
 999
1000                 self.ibox(indent_unit)?;
1001                 self.print_local_decl(&loc)?;
1002                 self.end()?;
1003                 if let Some(ref init) = loc.init {
1004                     self.nbsp()?;
1005                     self.word_space("=")?;
1006                     self.print_expr(&init)?;
1007                 }
1008                 self.end()?
1009             }
1010             hir::StmtKind::Item(item) => {
1011                 self.ann.nested(self, Nested::Item(item))?
1012             }
1013             hir::StmtKind::Expr(ref expr) => {
1014                 self.space_if_not_bol()?;
1015                 self.print_expr(&expr)?;
1016             }
1017             hir::StmtKind::Semi(ref expr) => {
1018                 self.space_if_not_bol()?;
1019                 self.print_expr(&expr)?;
1020                 self.s.word(";")?;
1021             }
1022         }
1023         if stmt_ends_with_semi(&st.node) {
1024             self.s.word(";")?;
1025         }
1026         self.maybe_print_trailing_comment(st.span, None)
1027     }
1028
1029     pub fn print_block(&mut self, blk: &hir::Block) -> io::Result<()> {
1030         self.print_block_with_attrs(blk, &[])
1031     }
1032
1033     pub fn print_block_unclosed(&mut self, blk: &hir::Block) -> io::Result<()> {
1034         self.print_block_unclosed_indent(blk, indent_unit)
1035     }
1036
1037     pub fn print_block_unclosed_indent(&mut self,
1038                                        blk: &hir::Block,
1039                                        indented: usize)
1040                                        -> io::Result<()> {
1041         self.print_block_maybe_unclosed(blk, indented, &[], false)
1042     }
1043
1044     pub fn print_block_with_attrs(&mut self,
1045                                   blk: &hir::Block,
1046                                   attrs: &[ast::Attribute])
1047                                   -> io::Result<()> {
1048         self.print_block_maybe_unclosed(blk, indent_unit, attrs, true)
1049     }
1050
1051     pub fn print_block_maybe_unclosed(&mut self,
1052                                       blk: &hir::Block,
1053                                       indented: usize,
1054                                       attrs: &[ast::Attribute],
1055                                       close_box: bool)
1056                                       -> io::Result<()> {
1057         match blk.rules {
1058             hir::UnsafeBlock(..) => self.word_space("unsafe")?,
1059             hir::PushUnsafeBlock(..) => self.word_space("push_unsafe")?,
1060             hir::PopUnsafeBlock(..) => self.word_space("pop_unsafe")?,
1061             hir::DefaultBlock => (),
1062         }
1063         self.maybe_print_comment(blk.span.lo())?;
1064         self.ann.pre(self, AnnNode::Block(blk))?;
1065         self.bopen()?;
1066
1067         self.print_inner_attributes(attrs)?;
1068
1069         for st in &blk.stmts {
1070             self.print_stmt(st)?;
1071         }
1072         if let Some(ref expr) = blk.expr {
1073             self.space_if_not_bol()?;
1074             self.print_expr(&expr)?;
1075             self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()))?;
1076         }
1077         self.bclose_maybe_open(blk.span, indented, close_box)?;
1078         self.ann.post(self, AnnNode::Block(blk))
1079     }
1080
1081     fn print_else(&mut self, els: Option<&hir::Expr>) -> io::Result<()> {
1082         match els {
1083             Some(_else) => {
1084                 match _else.node {
1085                     // "another else-if"
1086                     hir::ExprKind::If(ref i, ref then, ref e) => {
1087                         self.cbox(indent_unit - 1)?;
1088                         self.ibox(0)?;
1089                         self.s.word(" else if ")?;
1090                         self.print_expr_as_cond(&i)?;
1091                         self.s.space()?;
1092                         self.print_expr(&then)?;
1093                         self.print_else(e.as_ref().map(|e| &**e))
1094                     }
1095                     // "final else"
1096                     hir::ExprKind::Block(ref b, _) => {
1097                         self.cbox(indent_unit - 1)?;
1098                         self.ibox(0)?;
1099                         self.s.word(" else ")?;
1100                         self.print_block(&b)
1101                     }
1102                     // BLEAH, constraints would be great here
1103                     _ => {
1104                         panic!("print_if saw if with weird alternative");
1105                     }
1106                 }
1107             }
1108             _ => Ok(()),
1109         }
1110     }
1111
1112     pub fn print_if(&mut self,
1113                     test: &hir::Expr,
1114                     blk: &hir::Expr,
1115                     elseopt: Option<&hir::Expr>)
1116                     -> io::Result<()> {
1117         self.head("if")?;
1118         self.print_expr_as_cond(test)?;
1119         self.s.space()?;
1120         self.print_expr(blk)?;
1121         self.print_else(elseopt)
1122     }
1123
1124     pub fn print_if_let(&mut self,
1125                         pat: &hir::Pat,
1126                         expr: &hir::Expr,
1127                         blk: &hir::Block,
1128                         elseopt: Option<&hir::Expr>)
1129                         -> io::Result<()> {
1130         self.head("if let")?;
1131         self.print_pat(pat)?;
1132         self.s.space()?;
1133         self.word_space("=")?;
1134         self.print_expr_as_cond(expr)?;
1135         self.s.space()?;
1136         self.print_block(blk)?;
1137         self.print_else(elseopt)
1138     }
1139
1140     pub fn print_anon_const(&mut self, constant: &hir::AnonConst) -> io::Result<()> {
1141         self.ann.nested(self, Nested::Body(constant.body))
1142     }
1143
1144     fn print_call_post(&mut self, args: &[hir::Expr]) -> io::Result<()> {
1145         self.popen()?;
1146         self.commasep_exprs(Inconsistent, args)?;
1147         self.pclose()
1148     }
1149
1150     pub fn print_expr_maybe_paren(&mut self, expr: &hir::Expr, prec: i8) -> io::Result<()> {
1151         let needs_par = expr.precedence().order() < prec;
1152         if needs_par {
1153             self.popen()?;
1154         }
1155         self.print_expr(expr)?;
1156         if needs_par {
1157             self.pclose()?;
1158         }
1159         Ok(())
1160     }
1161
1162     /// Print an expr using syntax that's acceptable in a condition position, such as the `cond` in
1163     /// `if cond { ... }`.
1164     pub fn print_expr_as_cond(&mut self, expr: &hir::Expr) -> io::Result<()> {
1165         let needs_par = match expr.node {
1166             // These cases need parens due to the parse error observed in #26461: `if return {}`
1167             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1168             hir::ExprKind::Closure(..) |
1169             hir::ExprKind::Ret(..) |
1170             hir::ExprKind::Break(..) => true,
1171
1172             _ => contains_exterior_struct_lit(expr),
1173         };
1174
1175         if needs_par {
1176             self.popen()?;
1177         }
1178         self.print_expr(expr)?;
1179         if needs_par {
1180             self.pclose()?;
1181         }
1182         Ok(())
1183     }
1184
1185     fn print_expr_vec(&mut self, exprs: &[hir::Expr]) -> io::Result<()> {
1186         self.ibox(indent_unit)?;
1187         self.s.word("[")?;
1188         self.commasep_exprs(Inconsistent, exprs)?;
1189         self.s.word("]")?;
1190         self.end()
1191     }
1192
1193     fn print_expr_repeat(&mut self, element: &hir::Expr, count: &hir::AnonConst) -> io::Result<()> {
1194         self.ibox(indent_unit)?;
1195         self.s.word("[")?;
1196         self.print_expr(element)?;
1197         self.word_space(";")?;
1198         self.print_anon_const(count)?;
1199         self.s.word("]")?;
1200         self.end()
1201     }
1202
1203     fn print_expr_struct(&mut self,
1204                          qpath: &hir::QPath,
1205                          fields: &[hir::Field],
1206                          wth: &Option<P<hir::Expr>>)
1207                          -> io::Result<()> {
1208         self.print_qpath(qpath, true)?;
1209         self.s.word("{")?;
1210         self.commasep_cmnt(Consistent,
1211                            &fields[..],
1212                            |s, field| {
1213                                s.ibox(indent_unit)?;
1214                                if !field.is_shorthand {
1215                                     s.print_ident(field.ident)?;
1216                                     s.word_space(":")?;
1217                                }
1218                                s.print_expr(&field.expr)?;
1219                                s.end()
1220                            },
1221                            |f| f.span)?;
1222         match *wth {
1223             Some(ref expr) => {
1224                 self.ibox(indent_unit)?;
1225                 if !fields.is_empty() {
1226                     self.s.word(",")?;
1227                     self.s.space()?;
1228                 }
1229                 self.s.word("..")?;
1230                 self.print_expr(&expr)?;
1231                 self.end()?;
1232             }
1233             _ => if !fields.is_empty() {
1234                 self.s.word(",")?
1235             },
1236         }
1237         self.s.word("}")?;
1238         Ok(())
1239     }
1240
1241     fn print_expr_tup(&mut self, exprs: &[hir::Expr]) -> io::Result<()> {
1242         self.popen()?;
1243         self.commasep_exprs(Inconsistent, exprs)?;
1244         if exprs.len() == 1 {
1245             self.s.word(",")?;
1246         }
1247         self.pclose()
1248     }
1249
1250     fn print_expr_call(&mut self, func: &hir::Expr, args: &[hir::Expr]) -> io::Result<()> {
1251         let prec =
1252             match func.node {
1253                 hir::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1254                 _ => parser::PREC_POSTFIX,
1255             };
1256
1257         self.print_expr_maybe_paren(func, prec)?;
1258         self.print_call_post(args)
1259     }
1260
1261     fn print_expr_method_call(&mut self,
1262                               segment: &hir::PathSegment,
1263                               args: &[hir::Expr])
1264                               -> io::Result<()> {
1265         let base_args = &args[1..];
1266         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX)?;
1267         self.s.word(".")?;
1268         self.print_ident(segment.ident)?;
1269
1270         segment.with_generic_args(|generic_args| {
1271             if !generic_args.args.is_empty() || !generic_args.bindings.is_empty() {
1272                 return self.print_generic_args(&generic_args, segment.infer_types, true);
1273             }
1274             Ok(())
1275         })?;
1276         self.print_call_post(base_args)
1277     }
1278
1279     fn print_expr_binary(&mut self,
1280                          op: hir::BinOp,
1281                          lhs: &hir::Expr,
1282                          rhs: &hir::Expr)
1283                          -> io::Result<()> {
1284         let assoc_op = bin_op_to_assoc_op(op.node);
1285         let prec = assoc_op.precedence() as i8;
1286         let fixity = assoc_op.fixity();
1287
1288         let (left_prec, right_prec) = match fixity {
1289             Fixity::Left => (prec, prec + 1),
1290             Fixity::Right => (prec + 1, prec),
1291             Fixity::None => (prec + 1, prec + 1),
1292         };
1293
1294         let left_prec = match (&lhs.node, op.node) {
1295             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1296             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1297             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1298             (&hir::ExprKind::Cast { .. }, hir::BinOpKind::Lt) |
1299             (&hir::ExprKind::Cast { .. }, hir::BinOpKind::Shl) => parser::PREC_FORCE_PAREN,
1300             _ => left_prec,
1301         };
1302
1303         self.print_expr_maybe_paren(lhs, left_prec)?;
1304         self.s.space()?;
1305         self.word_space(op.node.as_str())?;
1306         self.print_expr_maybe_paren(rhs, right_prec)
1307     }
1308
1309     fn print_expr_unary(&mut self, op: hir::UnOp, expr: &hir::Expr) -> io::Result<()> {
1310         self.s.word(op.as_str())?;
1311         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1312     }
1313
1314     fn print_expr_addr_of(&mut self,
1315                           mutability: hir::Mutability,
1316                           expr: &hir::Expr)
1317                           -> io::Result<()> {
1318         self.s.word("&")?;
1319         self.print_mutability(mutability)?;
1320         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1321     }
1322
1323     pub fn print_expr(&mut self, expr: &hir::Expr) -> io::Result<()> {
1324         self.maybe_print_comment(expr.span.lo())?;
1325         self.print_outer_attributes(&expr.attrs)?;
1326         self.ibox(indent_unit)?;
1327         self.ann.pre(self, AnnNode::Expr(expr))?;
1328         match expr.node {
1329             hir::ExprKind::Box(ref expr) => {
1330                 self.word_space("box")?;
1331                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)?;
1332             }
1333             hir::ExprKind::Array(ref exprs) => {
1334                 self.print_expr_vec(exprs)?;
1335             }
1336             hir::ExprKind::Repeat(ref element, ref count) => {
1337                 self.print_expr_repeat(&element, count)?;
1338             }
1339             hir::ExprKind::Struct(ref qpath, ref fields, ref wth) => {
1340                 self.print_expr_struct(qpath, &fields[..], wth)?;
1341             }
1342             hir::ExprKind::Tup(ref exprs) => {
1343                 self.print_expr_tup(exprs)?;
1344             }
1345             hir::ExprKind::Call(ref func, ref args) => {
1346                 self.print_expr_call(&func, args)?;
1347             }
1348             hir::ExprKind::MethodCall(ref segment, _, ref args) => {
1349                 self.print_expr_method_call(segment, args)?;
1350             }
1351             hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
1352                 self.print_expr_binary(op, &lhs, &rhs)?;
1353             }
1354             hir::ExprKind::Unary(op, ref expr) => {
1355                 self.print_expr_unary(op, &expr)?;
1356             }
1357             hir::ExprKind::AddrOf(m, ref expr) => {
1358                 self.print_expr_addr_of(m, &expr)?;
1359             }
1360             hir::ExprKind::Lit(ref lit) => {
1361                 self.print_literal(&lit)?;
1362             }
1363             hir::ExprKind::Cast(ref expr, ref ty) => {
1364                 let prec = AssocOp::As.precedence() as i8;
1365                 self.print_expr_maybe_paren(&expr, prec)?;
1366                 self.s.space()?;
1367                 self.word_space("as")?;
1368                 self.print_type(&ty)?;
1369             }
1370             hir::ExprKind::Type(ref expr, ref ty) => {
1371                 let prec = AssocOp::Colon.precedence() as i8;
1372                 self.print_expr_maybe_paren(&expr, prec)?;
1373                 self.word_space(":")?;
1374                 self.print_type(&ty)?;
1375             }
1376             hir::ExprKind::If(ref test, ref blk, ref elseopt) => {
1377                 self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e))?;
1378             }
1379             hir::ExprKind::While(ref test, ref blk, opt_label) => {
1380                 if let Some(label) = opt_label {
1381                     self.print_ident(label.ident)?;
1382                     self.word_space(":")?;
1383                 }
1384                 self.head("while")?;
1385                 self.print_expr_as_cond(&test)?;
1386                 self.s.space()?;
1387                 self.print_block(&blk)?;
1388             }
1389             hir::ExprKind::Loop(ref blk, opt_label, _) => {
1390                 if let Some(label) = opt_label {
1391                     self.print_ident(label.ident)?;
1392                     self.word_space(":")?;
1393                 }
1394                 self.head("loop")?;
1395                 self.s.space()?;
1396                 self.print_block(&blk)?;
1397             }
1398             hir::ExprKind::Match(ref expr, ref arms, _) => {
1399                 self.cbox(indent_unit)?;
1400                 self.ibox(4)?;
1401                 self.word_nbsp("match")?;
1402                 self.print_expr_as_cond(&expr)?;
1403                 self.s.space()?;
1404                 self.bopen()?;
1405                 for arm in arms {
1406                     self.print_arm(arm)?;
1407                 }
1408                 self.bclose_(expr.span, indent_unit)?;
1409             }
1410             hir::ExprKind::Closure(capture_clause, ref decl, body, _fn_decl_span, _gen) => {
1411                 self.print_capture_clause(capture_clause)?;
1412
1413                 self.print_closure_args(&decl, body)?;
1414                 self.s.space()?;
1415
1416                 // this is a bare expression
1417                 self.ann.nested(self, Nested::Body(body))?;
1418                 self.end()?; // need to close a box
1419
1420                 // a box will be closed by print_expr, but we didn't want an overall
1421                 // wrapper so we closed the corresponding opening. so create an
1422                 // empty box to satisfy the close.
1423                 self.ibox(0)?;
1424             }
1425             hir::ExprKind::Block(ref blk, opt_label) => {
1426                 if let Some(label) = opt_label {
1427                     self.print_ident(label.ident)?;
1428                     self.word_space(":")?;
1429                 }
1430                 // containing cbox, will be closed by print-block at }
1431                 self.cbox(indent_unit)?;
1432                 // head-box, will be closed by print-block after {
1433                 self.ibox(0)?;
1434                 self.print_block(&blk)?;
1435             }
1436             hir::ExprKind::Assign(ref lhs, ref rhs) => {
1437                 let prec = AssocOp::Assign.precedence() as i8;
1438                 self.print_expr_maybe_paren(&lhs, prec + 1)?;
1439                 self.s.space()?;
1440                 self.word_space("=")?;
1441                 self.print_expr_maybe_paren(&rhs, prec)?;
1442             }
1443             hir::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
1444                 let prec = AssocOp::Assign.precedence() as i8;
1445                 self.print_expr_maybe_paren(&lhs, prec + 1)?;
1446                 self.s.space()?;
1447                 self.s.word(op.node.as_str())?;
1448                 self.word_space("=")?;
1449                 self.print_expr_maybe_paren(&rhs, prec)?;
1450             }
1451             hir::ExprKind::Field(ref expr, ident) => {
1452                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX)?;
1453                 self.s.word(".")?;
1454                 self.print_ident(ident)?;
1455             }
1456             hir::ExprKind::Index(ref expr, ref index) => {
1457                 self.print_expr_maybe_paren(&expr, parser::PREC_POSTFIX)?;
1458                 self.s.word("[")?;
1459                 self.print_expr(&index)?;
1460                 self.s.word("]")?;
1461             }
1462             hir::ExprKind::Path(ref qpath) => {
1463                 self.print_qpath(qpath, true)?
1464             }
1465             hir::ExprKind::Break(destination, ref opt_expr) => {
1466                 self.s.word("break")?;
1467                 self.s.space()?;
1468                 if let Some(label) = destination.label {
1469                     self.print_ident(label.ident)?;
1470                     self.s.space()?;
1471                 }
1472                 if let Some(ref expr) = *opt_expr {
1473                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP)?;
1474                     self.s.space()?;
1475                 }
1476             }
1477             hir::ExprKind::Continue(destination) => {
1478                 self.s.word("continue")?;
1479                 self.s.space()?;
1480                 if let Some(label) = destination.label {
1481                     self.print_ident(label.ident)?;
1482                     self.s.space()?
1483                 }
1484             }
1485             hir::ExprKind::Ret(ref result) => {
1486                 self.s.word("return")?;
1487                 if let Some(ref expr) = *result {
1488                     self.s.word(" ")?;
1489                     self.print_expr_maybe_paren(&expr, parser::PREC_JUMP)?;
1490                 }
1491             }
1492             hir::ExprKind::InlineAsm(ref a, ref outputs, ref inputs) => {
1493                 self.s.word("asm!")?;
1494                 self.popen()?;
1495                 self.print_string(&a.asm.as_str(), a.asm_str_style)?;
1496                 self.word_space(":")?;
1497
1498                 let mut out_idx = 0;
1499                 self.commasep(Inconsistent, &a.outputs, |s, out| {
1500                     let constraint = out.constraint.as_str();
1501                     let mut ch = constraint.chars();
1502                     match ch.next() {
1503                         Some('=') if out.is_rw => {
1504                             s.print_string(&format!("+{}", ch.as_str()),
1505                                            ast::StrStyle::Cooked)?
1506                         }
1507                         _ => s.print_string(&constraint, ast::StrStyle::Cooked)?,
1508                     }
1509                     s.popen()?;
1510                     s.print_expr(&outputs[out_idx])?;
1511                     s.pclose()?;
1512                     out_idx += 1;
1513                     Ok(())
1514                 })?;
1515                 self.s.space()?;
1516                 self.word_space(":")?;
1517
1518                 let mut in_idx = 0;
1519                 self.commasep(Inconsistent, &a.inputs, |s, co| {
1520                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
1521                     s.popen()?;
1522                     s.print_expr(&inputs[in_idx])?;
1523                     s.pclose()?;
1524                     in_idx += 1;
1525                     Ok(())
1526                 })?;
1527                 self.s.space()?;
1528                 self.word_space(":")?;
1529
1530                 self.commasep(Inconsistent, &a.clobbers, |s, co| {
1531                     s.print_string(&co.as_str(), ast::StrStyle::Cooked)?;
1532                     Ok(())
1533                 })?;
1534
1535                 let mut options = vec![];
1536                 if a.volatile {
1537                     options.push("volatile");
1538                 }
1539                 if a.alignstack {
1540                     options.push("alignstack");
1541                 }
1542                 if a.dialect == ast::AsmDialect::Intel {
1543                     options.push("intel");
1544                 }
1545
1546                 if !options.is_empty() {
1547                     self.s.space()?;
1548                     self.word_space(":")?;
1549                     self.commasep(Inconsistent, &options, |s, &co| {
1550                         s.print_string(co, ast::StrStyle::Cooked)?;
1551                         Ok(())
1552                     })?;
1553                 }
1554
1555                 self.pclose()?;
1556             }
1557             hir::ExprKind::Yield(ref expr) => {
1558                 self.word_space("yield")?;
1559                 self.print_expr_maybe_paren(&expr, parser::PREC_JUMP)?;
1560             }
1561             hir::ExprKind::Err => {
1562                 self.popen()?;
1563                 self.s.word("/*ERROR*/")?;
1564                 self.pclose()?;
1565             }
1566         }
1567         self.ann.post(self, AnnNode::Expr(expr))?;
1568         self.end()
1569     }
1570
1571     pub fn print_local_decl(&mut self, loc: &hir::Local) -> io::Result<()> {
1572         self.print_pat(&loc.pat)?;
1573         if let Some(ref ty) = loc.ty {
1574             self.word_space(":")?;
1575             self.print_type(&ty)?;
1576         }
1577         Ok(())
1578     }
1579
1580     pub fn print_usize(&mut self, i: usize) -> io::Result<()> {
1581         self.s.word(i.to_string())
1582     }
1583
1584     pub fn print_ident(&mut self, ident: ast::Ident) -> io::Result<()> {
1585         if ident.is_raw_guess() {
1586             self.s.word(format!("r#{}", ident.name))?;
1587         } else {
1588             self.s.word(ident.as_str().get())?;
1589         }
1590         self.ann.post(self, AnnNode::Name(&ident.name))
1591     }
1592
1593     pub fn print_name(&mut self, name: ast::Name) -> io::Result<()> {
1594         self.print_ident(ast::Ident::with_empty_ctxt(name))
1595     }
1596
1597     pub fn print_for_decl(&mut self, loc: &hir::Local, coll: &hir::Expr) -> io::Result<()> {
1598         self.print_local_decl(loc)?;
1599         self.s.space()?;
1600         self.word_space("in")?;
1601         self.print_expr(coll)
1602     }
1603
1604     pub fn print_path(&mut self,
1605                       path: &hir::Path,
1606                       colons_before_params: bool)
1607                       -> io::Result<()> {
1608         self.maybe_print_comment(path.span.lo())?;
1609
1610         for (i, segment) in path.segments.iter().enumerate() {
1611             if i > 0 {
1612                 self.s.word("::")?
1613             }
1614             if segment.ident.name != keywords::PathRoot.name() {
1615                self.print_ident(segment.ident)?;
1616                segment.with_generic_args(|generic_args| {
1617                    self.print_generic_args(generic_args, segment.infer_types,
1618                                            colons_before_params)
1619                })?;
1620             }
1621         }
1622
1623         Ok(())
1624     }
1625
1626     pub fn print_path_segment(&mut self, segment: &hir::PathSegment) -> io::Result<()> {
1627         if segment.ident.name != keywords::PathRoot.name() {
1628            self.print_ident(segment.ident)?;
1629            segment.with_generic_args(|generic_args| {
1630                self.print_generic_args(generic_args, segment.infer_types, false)
1631            })?;
1632         }
1633         Ok(())
1634     }
1635
1636     pub fn print_qpath(&mut self,
1637                        qpath: &hir::QPath,
1638                        colons_before_params: bool)
1639                        -> io::Result<()> {
1640         match *qpath {
1641             hir::QPath::Resolved(None, ref path) => {
1642                 self.print_path(path, colons_before_params)
1643             }
1644             hir::QPath::Resolved(Some(ref qself), ref path) => {
1645                 self.s.word("<")?;
1646                 self.print_type(qself)?;
1647                 self.s.space()?;
1648                 self.word_space("as")?;
1649
1650                 for (i, segment) in path.segments[..path.segments.len() - 1].iter().enumerate() {
1651                     if i > 0 {
1652                         self.s.word("::")?
1653                     }
1654                     if segment.ident.name != keywords::PathRoot.name() {
1655                         self.print_ident(segment.ident)?;
1656                         segment.with_generic_args(|generic_args| {
1657                             self.print_generic_args(generic_args,
1658                                                     segment.infer_types,
1659                                                     colons_before_params)
1660                         })?;
1661                     }
1662                 }
1663
1664                 self.s.word(">")?;
1665                 self.s.word("::")?;
1666                 let item_segment = path.segments.last().unwrap();
1667                 self.print_ident(item_segment.ident)?;
1668                 item_segment.with_generic_args(|generic_args| {
1669                     self.print_generic_args(generic_args,
1670                                             item_segment.infer_types,
1671                                             colons_before_params)
1672                 })
1673             }
1674             hir::QPath::TypeRelative(ref qself, ref item_segment) => {
1675                 self.s.word("<")?;
1676                 self.print_type(qself)?;
1677                 self.s.word(">")?;
1678                 self.s.word("::")?;
1679                 self.print_ident(item_segment.ident)?;
1680                 item_segment.with_generic_args(|generic_args| {
1681                     self.print_generic_args(generic_args,
1682                                             item_segment.infer_types,
1683                                             colons_before_params)
1684                 })
1685             }
1686         }
1687     }
1688
1689     fn print_generic_args(&mut self,
1690                              generic_args: &hir::GenericArgs,
1691                              infer_types: bool,
1692                              colons_before_params: bool)
1693                              -> io::Result<()> {
1694         if generic_args.parenthesized {
1695             self.s.word("(")?;
1696             self.commasep(Inconsistent, generic_args.inputs(), |s, ty| s.print_type(&ty))?;
1697             self.s.word(")")?;
1698
1699             self.space_if_not_bol()?;
1700             self.word_space("->")?;
1701             self.print_type(&generic_args.bindings[0].ty)?;
1702         } else {
1703             let start = if colons_before_params { "::<" } else { "<" };
1704             let empty = Cell::new(true);
1705             let start_or_comma = |this: &mut Self| {
1706                 if empty.get() {
1707                     empty.set(false);
1708                     this.s.word(start)
1709                 } else {
1710                     this.word_space(",")
1711                 }
1712             };
1713
1714             let mut nonelided_generic_args: bool = false;
1715             let elide_lifetimes = generic_args.args.iter().all(|arg| match arg {
1716                 GenericArg::Lifetime(lt) => lt.is_elided(),
1717                 _ => {
1718                     nonelided_generic_args = true;
1719                     true
1720                 }
1721             });
1722
1723             if nonelided_generic_args {
1724                 start_or_comma(self)?;
1725                 self.commasep(Inconsistent, &generic_args.args, |s, generic_arg| {
1726                     match generic_arg {
1727                         GenericArg::Lifetime(lt) if !elide_lifetimes => s.print_lifetime(lt),
1728                         GenericArg::Lifetime(_) => Ok(()),
1729                         GenericArg::Type(ty) => s.print_type(ty),
1730                         GenericArg::Const(ct) => s.print_anon_const(&ct.value),
1731                     }
1732                 })?;
1733             }
1734
1735             // FIXME(eddyb) This would leak into error messages, e.g.:
1736             // "non-exhaustive patterns: `Some::<..>(_)` not covered".
1737             if infer_types && false {
1738                 start_or_comma(self)?;
1739                 self.s.word("..")?;
1740             }
1741
1742             for binding in generic_args.bindings.iter() {
1743                 start_or_comma(self)?;
1744                 self.print_ident(binding.ident)?;
1745                 self.s.space()?;
1746                 self.word_space("=")?;
1747                 self.print_type(&binding.ty)?;
1748             }
1749
1750             if !empty.get() {
1751                 self.s.word(">")?
1752             }
1753         }
1754
1755         Ok(())
1756     }
1757
1758     pub fn print_pat(&mut self, pat: &hir::Pat) -> io::Result<()> {
1759         self.maybe_print_comment(pat.span.lo())?;
1760         self.ann.pre(self, AnnNode::Pat(pat))?;
1761         // Pat isn't normalized, but the beauty of it
1762         // is that it doesn't matter
1763         match pat.node {
1764             PatKind::Wild => self.s.word("_")?,
1765             PatKind::Binding(binding_mode, _, _, ident, ref sub) => {
1766                 match binding_mode {
1767                     hir::BindingAnnotation::Ref => {
1768                         self.word_nbsp("ref")?;
1769                         self.print_mutability(hir::MutImmutable)?;
1770                     }
1771                     hir::BindingAnnotation::RefMut => {
1772                         self.word_nbsp("ref")?;
1773                         self.print_mutability(hir::MutMutable)?;
1774                     }
1775                     hir::BindingAnnotation::Unannotated => {}
1776                     hir::BindingAnnotation::Mutable => {
1777                         self.word_nbsp("mut")?;
1778                     }
1779                 }
1780                 self.print_ident(ident)?;
1781                 if let Some(ref p) = *sub {
1782                     self.s.word("@")?;
1783                     self.print_pat(&p)?;
1784                 }
1785             }
1786             PatKind::TupleStruct(ref qpath, ref elts, ddpos) => {
1787                 self.print_qpath(qpath, true)?;
1788                 self.popen()?;
1789                 if let Some(ddpos) = ddpos {
1790                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p))?;
1791                     if ddpos != 0 {
1792                         self.word_space(",")?;
1793                     }
1794                     self.s.word("..")?;
1795                     if ddpos != elts.len() {
1796                         self.s.word(",")?;
1797                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
1798                     }
1799                 } else {
1800                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
1801                 }
1802                 self.pclose()?;
1803             }
1804             PatKind::Path(ref qpath) => {
1805                 self.print_qpath(qpath, true)?;
1806             }
1807             PatKind::Struct(ref qpath, ref fields, etc) => {
1808                 self.print_qpath(qpath, true)?;
1809                 self.nbsp()?;
1810                 self.word_space("{")?;
1811                 self.commasep_cmnt(Consistent,
1812                                    &fields[..],
1813                                    |s, f| {
1814                                        s.cbox(indent_unit)?;
1815                                        if !f.node.is_shorthand {
1816                                            s.print_ident(f.node.ident)?;
1817                                            s.word_nbsp(":")?;
1818                                        }
1819                                        s.print_pat(&f.node.pat)?;
1820                                        s.end()
1821                                    },
1822                                    |f| f.node.pat.span)?;
1823                 if etc {
1824                     if !fields.is_empty() {
1825                         self.word_space(",")?;
1826                     }
1827                     self.s.word("..")?;
1828                 }
1829                 self.s.space()?;
1830                 self.s.word("}")?;
1831             }
1832             PatKind::Tuple(ref elts, ddpos) => {
1833                 self.popen()?;
1834                 if let Some(ddpos) = ddpos {
1835                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p))?;
1836                     if ddpos != 0 {
1837                         self.word_space(",")?;
1838                     }
1839                     self.s.word("..")?;
1840                     if ddpos != elts.len() {
1841                         self.s.word(",")?;
1842                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p))?;
1843                     }
1844                 } else {
1845                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p))?;
1846                     if elts.len() == 1 {
1847                         self.s.word(",")?;
1848                     }
1849                 }
1850                 self.pclose()?;
1851             }
1852             PatKind::Box(ref inner) => {
1853                 let is_range_inner = match inner.node {
1854                     PatKind::Range(..) => true,
1855                     _ => false,
1856                 };
1857                 self.s.word("box ")?;
1858                 if is_range_inner {
1859                     self.popen()?;
1860                 }
1861                 self.print_pat(&inner)?;
1862                 if is_range_inner {
1863                     self.pclose()?;
1864                 }
1865             }
1866             PatKind::Ref(ref inner, mutbl) => {
1867                 let is_range_inner = match inner.node {
1868                     PatKind::Range(..) => true,
1869                     _ => false,
1870                 };
1871                 self.s.word("&")?;
1872                 if mutbl == hir::MutMutable {
1873                     self.s.word("mut ")?;
1874                 }
1875                 if is_range_inner {
1876                     self.popen()?;
1877                 }
1878                 self.print_pat(&inner)?;
1879                 if is_range_inner {
1880                     self.pclose()?;
1881                 }
1882             }
1883             PatKind::Lit(ref e) => self.print_expr(&e)?,
1884             PatKind::Range(ref begin, ref end, ref end_kind) => {
1885                 self.print_expr(&begin)?;
1886                 self.s.space()?;
1887                 match *end_kind {
1888                     RangeEnd::Included => self.s.word("...")?,
1889                     RangeEnd::Excluded => self.s.word("..")?,
1890                 }
1891                 self.print_expr(&end)?;
1892             }
1893             PatKind::Slice(ref before, ref slice, ref after) => {
1894                 self.s.word("[")?;
1895                 self.commasep(Inconsistent, &before[..], |s, p| s.print_pat(&p))?;
1896                 if let Some(ref p) = *slice {
1897                     if !before.is_empty() {
1898                         self.word_space(",")?;
1899                     }
1900                     if let PatKind::Wild = p.node {
1901                         // Print nothing
1902                     } else {
1903                         self.print_pat(&p)?;
1904                     }
1905                     self.s.word("..")?;
1906                     if !after.is_empty() {
1907                         self.word_space(",")?;
1908                     }
1909                 }
1910                 self.commasep(Inconsistent, &after[..], |s, p| s.print_pat(&p))?;
1911                 self.s.word("]")?;
1912             }
1913         }
1914         self.ann.post(self, AnnNode::Pat(pat))
1915     }
1916
1917     fn print_arm(&mut self, arm: &hir::Arm) -> io::Result<()> {
1918         // I have no idea why this check is necessary, but here it
1919         // is :(
1920         if arm.attrs.is_empty() {
1921             self.s.space()?;
1922         }
1923         self.cbox(indent_unit)?;
1924         self.ibox(0)?;
1925         self.print_outer_attributes(&arm.attrs)?;
1926         let mut first = true;
1927         for p in &arm.pats {
1928             if first {
1929                 first = false;
1930             } else {
1931                 self.s.space()?;
1932                 self.word_space("|")?;
1933             }
1934             self.print_pat(&p)?;
1935         }
1936         self.s.space()?;
1937         if let Some(ref g) = arm.guard {
1938             match g {
1939                 hir::Guard::If(e) => {
1940                     self.word_space("if")?;
1941                     self.print_expr(&e)?;
1942                     self.s.space()?;
1943                 }
1944             }
1945         }
1946         self.word_space("=>")?;
1947
1948         match arm.body.node {
1949             hir::ExprKind::Block(ref blk, opt_label) => {
1950                 if let Some(label) = opt_label {
1951                     self.print_ident(label.ident)?;
1952                     self.word_space(":")?;
1953                 }
1954                 // the block will close the pattern's ibox
1955                 self.print_block_unclosed_indent(&blk, indent_unit)?;
1956
1957                 // If it is a user-provided unsafe block, print a comma after it
1958                 if let hir::UnsafeBlock(hir::UserProvided) = blk.rules {
1959                     self.s.word(",")?;
1960                 }
1961             }
1962             _ => {
1963                 self.end()?; // close the ibox for the pattern
1964                 self.print_expr(&arm.body)?;
1965                 self.s.word(",")?;
1966             }
1967         }
1968         self.end() // close enclosing cbox
1969     }
1970
1971     pub fn print_fn(&mut self,
1972                     decl: &hir::FnDecl,
1973                     header: hir::FnHeader,
1974                     name: Option<ast::Name>,
1975                     generics: &hir::Generics,
1976                     vis: &hir::Visibility,
1977                     arg_names: &[ast::Ident],
1978                     body_id: Option<hir::BodyId>)
1979                     -> io::Result<()> {
1980         self.print_fn_header_info(header, vis)?;
1981
1982         if let Some(name) = name {
1983             self.nbsp()?;
1984             self.print_name(name)?;
1985         }
1986         self.print_generic_params(&generics.params)?;
1987
1988         self.popen()?;
1989         let mut i = 0;
1990         // Make sure we aren't supplied *both* `arg_names` and `body_id`.
1991         assert!(arg_names.is_empty() || body_id.is_none());
1992         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
1993             s.ibox(indent_unit)?;
1994             if let Some(arg_name) = arg_names.get(i) {
1995                 s.s.word(arg_name.as_str().get())?;
1996                 s.s.word(":")?;
1997                 s.s.space()?;
1998             } else if let Some(body_id) = body_id {
1999                 s.ann.nested(s, Nested::BodyArgPat(body_id, i))?;
2000                 s.s.word(":")?;
2001                 s.s.space()?;
2002             }
2003             i += 1;
2004             s.print_type(ty)?;
2005             s.end()
2006         })?;
2007         if decl.variadic {
2008             self.s.word(", ...")?;
2009         }
2010         self.pclose()?;
2011
2012         self.print_fn_output(decl)?;
2013         self.print_where_clause(&generics.where_clause)
2014     }
2015
2016     fn print_closure_args(&mut self, decl: &hir::FnDecl, body_id: hir::BodyId) -> io::Result<()> {
2017         self.s.word("|")?;
2018         let mut i = 0;
2019         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
2020             s.ibox(indent_unit)?;
2021
2022             s.ann.nested(s, Nested::BodyArgPat(body_id, i))?;
2023             i += 1;
2024
2025             if let hir::TyKind::Infer = ty.node {
2026                 // Print nothing
2027             } else {
2028                 s.s.word(":")?;
2029                 s.s.space()?;
2030                 s.print_type(ty)?;
2031             }
2032             s.end()
2033         })?;
2034         self.s.word("|")?;
2035
2036         if let hir::DefaultReturn(..) = decl.output {
2037             return Ok(());
2038         }
2039
2040         self.space_if_not_bol()?;
2041         self.word_space("->")?;
2042         match decl.output {
2043             hir::Return(ref ty) => {
2044                 self.print_type(&ty)?;
2045                 self.maybe_print_comment(ty.span.lo())
2046             }
2047             hir::DefaultReturn(..) => unreachable!(),
2048         }
2049     }
2050
2051     pub fn print_capture_clause(&mut self, capture_clause: hir::CaptureClause) -> io::Result<()> {
2052         match capture_clause {
2053             hir::CaptureByValue => self.word_space("move"),
2054             hir::CaptureByRef => Ok(()),
2055         }
2056     }
2057
2058     pub fn print_bounds(&mut self, prefix: &'static str, bounds: &[hir::GenericBound])
2059                         -> io::Result<()> {
2060         if !bounds.is_empty() {
2061             self.s.word(prefix)?;
2062             let mut first = true;
2063             for bound in bounds {
2064                 if !(first && prefix.is_empty()) {
2065                     self.nbsp()?;
2066                 }
2067                 if first {
2068                     first = false;
2069                 } else {
2070                     self.word_space("+")?;
2071                 }
2072
2073                 match bound {
2074                     GenericBound::Trait(tref, modifier) => {
2075                         if modifier == &TraitBoundModifier::Maybe {
2076                             self.s.word("?")?;
2077                         }
2078                         self.print_poly_trait_ref(tref)?;
2079                     }
2080                     GenericBound::Outlives(lt) => {
2081                         self.print_lifetime(lt)?;
2082                     }
2083                 }
2084             }
2085         }
2086         Ok(())
2087     }
2088
2089     pub fn print_generic_params(&mut self, generic_params: &[GenericParam]) -> io::Result<()> {
2090         if !generic_params.is_empty() {
2091             self.s.word("<")?;
2092
2093             self.commasep(Inconsistent, generic_params, |s, param| {
2094                 s.print_generic_param(param)
2095             })?;
2096
2097             self.s.word(">")?;
2098         }
2099         Ok(())
2100     }
2101
2102     pub fn print_generic_param(&mut self, param: &GenericParam) -> io::Result<()> {
2103         if let GenericParamKind::Const { .. } = param.kind {
2104             self.word_space("const")?;
2105         }
2106
2107         self.print_ident(param.name.ident())?;
2108
2109         match param.kind {
2110             GenericParamKind::Lifetime { .. } => {
2111                 let mut sep = ":";
2112                 for bound in &param.bounds {
2113                     match bound {
2114                         GenericBound::Outlives(lt) => {
2115                             self.s.word(sep)?;
2116                             self.print_lifetime(lt)?;
2117                             sep = "+";
2118                         }
2119                         _ => bug!(),
2120                     }
2121                 }
2122                 Ok(())
2123             }
2124             GenericParamKind::Type { ref default, .. } => {
2125                 self.print_bounds(":", &param.bounds)?;
2126                 match default {
2127                     Some(default) => {
2128                         self.s.space()?;
2129                         self.word_space("=")?;
2130                         self.print_type(&default)
2131                     }
2132                     _ => Ok(()),
2133                 }
2134             }
2135             GenericParamKind::Const { ref ty } => {
2136                 self.word_space(":")?;
2137                 self.print_type(ty)
2138             }
2139         }
2140     }
2141
2142     pub fn print_lifetime(&mut self, lifetime: &hir::Lifetime) -> io::Result<()> {
2143         self.print_ident(lifetime.name.ident())
2144     }
2145
2146     pub fn print_where_clause(&mut self, where_clause: &hir::WhereClause) -> io::Result<()> {
2147         if where_clause.predicates.is_empty() {
2148             return Ok(());
2149         }
2150
2151         self.s.space()?;
2152         self.word_space("where")?;
2153
2154         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2155             if i != 0 {
2156                 self.word_space(",")?;
2157             }
2158
2159             match predicate {
2160                 &hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
2161                     ref bound_generic_params,
2162                     ref bounded_ty,
2163                     ref bounds,
2164                     ..
2165                 }) => {
2166                     self.print_formal_generic_params(bound_generic_params)?;
2167                     self.print_type(&bounded_ty)?;
2168                     self.print_bounds(":", bounds)?;
2169                 }
2170                 &hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate{ref lifetime,
2171                                                                                 ref bounds,
2172                                                                                 ..}) => {
2173                     self.print_lifetime(lifetime)?;
2174                     self.s.word(":")?;
2175
2176                     for (i, bound) in bounds.iter().enumerate() {
2177                         match bound {
2178                             GenericBound::Outlives(lt) => {
2179                                 self.print_lifetime(lt)?;
2180                             }
2181                             _ => bug!(),
2182                         }
2183
2184                         if i != 0 {
2185                             self.s.word(":")?;
2186                         }
2187                     }
2188                 }
2189                 &hir::WherePredicate::EqPredicate(hir::WhereEqPredicate{ref lhs_ty,
2190                                                                         ref rhs_ty,
2191                                                                         ..}) => {
2192                     self.print_type(lhs_ty)?;
2193                     self.s.space()?;
2194                     self.word_space("=")?;
2195                     self.print_type(rhs_ty)?;
2196                 }
2197             }
2198         }
2199
2200         Ok(())
2201     }
2202
2203     pub fn print_mutability(&mut self, mutbl: hir::Mutability) -> io::Result<()> {
2204         match mutbl {
2205             hir::MutMutable => self.word_nbsp("mut"),
2206             hir::MutImmutable => Ok(()),
2207         }
2208     }
2209
2210     pub fn print_mt(&mut self, mt: &hir::MutTy) -> io::Result<()> {
2211         self.print_mutability(mt.mutbl)?;
2212         self.print_type(&mt.ty)
2213     }
2214
2215     pub fn print_fn_output(&mut self, decl: &hir::FnDecl) -> io::Result<()> {
2216         if let hir::DefaultReturn(..) = decl.output {
2217             return Ok(());
2218         }
2219
2220         self.space_if_not_bol()?;
2221         self.ibox(indent_unit)?;
2222         self.word_space("->")?;
2223         match decl.output {
2224             hir::DefaultReturn(..) => unreachable!(),
2225             hir::Return(ref ty) => self.print_type(&ty)?,
2226         }
2227         self.end()?;
2228
2229         match decl.output {
2230             hir::Return(ref output) => self.maybe_print_comment(output.span.lo()),
2231             _ => Ok(()),
2232         }
2233     }
2234
2235     pub fn print_ty_fn(&mut self,
2236                        abi: Abi,
2237                        unsafety: hir::Unsafety,
2238                        decl: &hir::FnDecl,
2239                        name: Option<ast::Name>,
2240                        generic_params: &[hir::GenericParam],
2241                        arg_names: &[ast::Ident])
2242                        -> io::Result<()> {
2243         self.ibox(indent_unit)?;
2244         if !generic_params.is_empty() {
2245             self.s.word("for")?;
2246             self.print_generic_params(generic_params)?;
2247         }
2248         let generics = hir::Generics {
2249             params: hir::HirVec::new(),
2250             where_clause: hir::WhereClause {
2251                 hir_id: hir::DUMMY_HIR_ID,
2252                 predicates: hir::HirVec::new(),
2253             },
2254             span: syntax_pos::DUMMY_SP,
2255         };
2256         self.print_fn(decl,
2257                       hir::FnHeader {
2258                           unsafety,
2259                           abi,
2260                           constness: hir::Constness::NotConst,
2261                           asyncness: hir::IsAsync::NotAsync,
2262                       },
2263                       name,
2264                       &generics,
2265                       &Spanned { span: syntax_pos::DUMMY_SP,
2266                                  node: hir::VisibilityKind::Inherited },
2267                       arg_names,
2268                       None)?;
2269         self.end()
2270     }
2271
2272     pub fn maybe_print_trailing_comment(&mut self,
2273                                         span: syntax_pos::Span,
2274                                         next_pos: Option<BytePos>)
2275                                         -> io::Result<()> {
2276         let cm = match self.cm {
2277             Some(cm) => cm,
2278             _ => return Ok(()),
2279         };
2280         if let Some(ref cmnt) = self.next_comment() {
2281             if (*cmnt).style != comments::Trailing {
2282                 return Ok(());
2283             }
2284             let span_line = cm.lookup_char_pos(span.hi());
2285             let comment_line = cm.lookup_char_pos((*cmnt).pos);
2286             let mut next = (*cmnt).pos + BytePos(1);
2287             if let Some(p) = next_pos {
2288                 next = p;
2289             }
2290             if span.hi() < (*cmnt).pos && (*cmnt).pos < next &&
2291                span_line.line == comment_line.line {
2292                 self.print_comment(cmnt)?;
2293             }
2294         }
2295         Ok(())
2296     }
2297
2298     pub fn print_remaining_comments(&mut self) -> io::Result<()> {
2299         // If there aren't any remaining comments, then we need to manually
2300         // make sure there is a line break at the end.
2301         if self.next_comment().is_none() {
2302             self.s.hardbreak()?;
2303         }
2304         while let Some(ref cmnt) = self.next_comment() {
2305             self.print_comment(cmnt)?
2306         }
2307         Ok(())
2308     }
2309
2310     pub fn print_opt_abi_and_extern_if_nondefault(&mut self,
2311                                                   opt_abi: Option<Abi>)
2312                                                   -> io::Result<()> {
2313         match opt_abi {
2314             Some(Abi::Rust) => Ok(()),
2315             Some(abi) => {
2316                 self.word_nbsp("extern")?;
2317                 self.word_nbsp(abi.to_string())
2318             }
2319             None => Ok(()),
2320         }
2321     }
2322
2323     pub fn print_extern_opt_abi(&mut self, opt_abi: Option<Abi>) -> io::Result<()> {
2324         match opt_abi {
2325             Some(abi) => {
2326                 self.word_nbsp("extern")?;
2327                 self.word_nbsp(abi.to_string())
2328             }
2329             None => Ok(()),
2330         }
2331     }
2332
2333     pub fn print_fn_header_info(&mut self,
2334                                 header: hir::FnHeader,
2335                                 vis: &hir::Visibility)
2336                                 -> io::Result<()> {
2337         self.s.word(visibility_qualified(vis, ""))?;
2338
2339         match header.constness {
2340             hir::Constness::NotConst => {}
2341             hir::Constness::Const => self.word_nbsp("const")?,
2342         }
2343
2344         match header.asyncness {
2345             hir::IsAsync::NotAsync => {}
2346             hir::IsAsync::Async => self.word_nbsp("async")?,
2347         }
2348
2349         self.print_unsafety(header.unsafety)?;
2350
2351         if header.abi != Abi::Rust {
2352             self.word_nbsp("extern")?;
2353             self.word_nbsp(header.abi.to_string())?;
2354         }
2355
2356         self.s.word("fn")
2357     }
2358
2359     pub fn print_unsafety(&mut self, s: hir::Unsafety) -> io::Result<()> {
2360         match s {
2361             hir::Unsafety::Normal => Ok(()),
2362             hir::Unsafety::Unsafe => self.word_nbsp("unsafe"),
2363         }
2364     }
2365
2366     pub fn print_is_auto(&mut self, s: hir::IsAuto) -> io::Result<()> {
2367         match s {
2368             hir::IsAuto::Yes => self.word_nbsp("auto"),
2369             hir::IsAuto::No => Ok(()),
2370         }
2371     }
2372 }
2373
2374 // Dup'ed from parse::classify, but adapted for the HIR.
2375 /// Does this expression require a semicolon to be treated
2376 /// as a statement? The negation of this: 'can this expression
2377 /// be used as a statement without a semicolon' -- is used
2378 /// as an early-bail-out in the parser so that, for instance,
2379 ///     if true {...} else {...}
2380 ///      |x| 5
2381 /// isn't parsed as (if true {...} else {...} | x) | 5
2382 fn expr_requires_semi_to_be_stmt(e: &hir::Expr) -> bool {
2383     match e.node {
2384         hir::ExprKind::If(..) |
2385         hir::ExprKind::Match(..) |
2386         hir::ExprKind::Block(..) |
2387         hir::ExprKind::While(..) |
2388         hir::ExprKind::Loop(..) => false,
2389         _ => true,
2390     }
2391 }
2392
2393 /// this statement requires a semicolon after it.
2394 /// note that in one case (stmt_semi), we've already
2395 /// seen the semicolon, and thus don't need another.
2396 fn stmt_ends_with_semi(stmt: &hir::StmtKind) -> bool {
2397     match *stmt {
2398         hir::StmtKind::Local(_) => true,
2399         hir::StmtKind::Item(_) => false,
2400         hir::StmtKind::Expr(ref e) => expr_requires_semi_to_be_stmt(&e),
2401         hir::StmtKind::Semi(..) => false,
2402     }
2403 }
2404
2405 fn bin_op_to_assoc_op(op: hir::BinOpKind) -> AssocOp {
2406     use crate::hir::BinOpKind::*;
2407     match op {
2408         Add => AssocOp::Add,
2409         Sub => AssocOp::Subtract,
2410         Mul => AssocOp::Multiply,
2411         Div => AssocOp::Divide,
2412         Rem => AssocOp::Modulus,
2413
2414         And => AssocOp::LAnd,
2415         Or => AssocOp::LOr,
2416
2417         BitXor => AssocOp::BitXor,
2418         BitAnd => AssocOp::BitAnd,
2419         BitOr => AssocOp::BitOr,
2420         Shl => AssocOp::ShiftLeft,
2421         Shr => AssocOp::ShiftRight,
2422
2423         Eq => AssocOp::Equal,
2424         Lt => AssocOp::Less,
2425         Le => AssocOp::LessEqual,
2426         Ne => AssocOp::NotEqual,
2427         Ge => AssocOp::GreaterEqual,
2428         Gt => AssocOp::Greater,
2429     }
2430 }
2431
2432 /// Expressions that syntactically contain an "exterior" struct literal i.e., not surrounded by any
2433 /// parens or other delimiters, e.g., `X { y: 1 }`, `X { y: 1 }.method()`, `foo == X { y: 1 }` and
2434 /// `X { y: 1 } == foo` all do, but `(X { y: 1 }) == foo` does not.
2435 fn contains_exterior_struct_lit(value: &hir::Expr) -> bool {
2436     match value.node {
2437         hir::ExprKind::Struct(..) => true,
2438
2439         hir::ExprKind::Assign(ref lhs, ref rhs) |
2440         hir::ExprKind::AssignOp(_, ref lhs, ref rhs) |
2441         hir::ExprKind::Binary(_, ref lhs, ref rhs) => {
2442             // X { y: 1 } + X { y: 2 }
2443             contains_exterior_struct_lit(&lhs) || contains_exterior_struct_lit(&rhs)
2444         }
2445         hir::ExprKind::Unary(_, ref x) |
2446         hir::ExprKind::Cast(ref x, _) |
2447         hir::ExprKind::Type(ref x, _) |
2448         hir::ExprKind::Field(ref x, _) |
2449         hir::ExprKind::Index(ref x, _) => {
2450             // &X { y: 1 }, X { y: 1 }.y
2451             contains_exterior_struct_lit(&x)
2452         }
2453
2454         hir::ExprKind::MethodCall(.., ref exprs) => {
2455             // X { y: 1 }.bar(...)
2456             contains_exterior_struct_lit(&exprs[0])
2457         }
2458
2459         _ => false,
2460     }
2461 }