compiler/rustc_hir_pretty/src/lib.rs

   1 #![feature(or_patterns)]
   2 #![recursion_limit = "256"]
   3
   4 use rustc_ast as ast;
   5 use rustc_ast::util::parser::{self, AssocOp, Fixity};
   6 use rustc_ast_pretty::pp::Breaks::{Consistent, Inconsistent};
   7 use rustc_ast_pretty::pp::{self, Breaks};
   8 use rustc_ast_pretty::pprust::{Comments, PrintState};
   9 use rustc_hir as hir;
  10 use rustc_hir::{GenericArg, GenericParam, GenericParamKind, Node};
  11 use rustc_hir::{GenericBound, PatKind, RangeEnd, TraitBoundModifier};
  12 use rustc_span::source_map::{SourceMap, Spanned};
  13 use rustc_span::symbol::{kw, Ident, IdentPrinter, Symbol};
  14 use rustc_span::{self, BytePos, FileName};
  15 use rustc_target::spec::abi::Abi;
  16
  17 use std::borrow::Cow;
  18 use std::cell::Cell;
  19 use std::vec;
  20
  21 pub fn id_to_string(map: &dyn rustc_hir::intravisit::Map<'_>, hir_id: hir::HirId) -> String {
  22     to_string(&map, |s| s.print_node(map.find(hir_id).unwrap()))
  23 }
  24
  25 pub enum AnnNode<'a> {
  26     Name(&'a Symbol),
  27     Block(&'a hir::Block<'a>),
  28     Item(&'a hir::Item<'a>),
  29     SubItem(hir::HirId),
  30     Expr(&'a hir::Expr<'a>),
  31     Pat(&'a hir::Pat<'a>),
  32     Arm(&'a hir::Arm<'a>),
  33 }
  34
  35 pub enum Nested {
  36     Item(hir::ItemId),
  37     TraitItem(hir::TraitItemId),
  38     ImplItem(hir::ImplItemId),
  39     Body(hir::BodyId),
  40     BodyParamPat(hir::BodyId, usize),
  41 }
  42
  43 pub trait PpAnn {
  44     fn nested(&self, _state: &mut State<'_>, _nested: Nested) {}
  45     fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
  46     fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
  47     fn try_fetch_item(&self, _: hir::HirId) -> Option<&hir::Item<'_>> {
  48         None
  49     }
  50 }
  51
  52 pub struct NoAnn;
  53 impl PpAnn for NoAnn {}
  54 pub const NO_ANN: &dyn PpAnn = &NoAnn;
  55
  56 impl PpAnn for hir::Crate<'_> {
  57     fn try_fetch_item(&self, item: hir::HirId) -> Option<&hir::Item<'_>> {
  58         Some(self.item(item))
  59     }
  60     fn nested(&self, state: &mut State<'_>, nested: Nested) {
  61         match nested {
  62             Nested::Item(id) => state.print_item(self.item(id.id)),
  63             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
  64             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
  65             Nested::Body(id) => state.print_expr(&self.body(id).value),
  66             Nested::BodyParamPat(id, i) => state.print_pat(&self.body(id).params[i].pat),
  67         }
  68     }
  69 }
  70
  71 /// Identical to the `PpAnn` implementation for `hir::Crate`,
  72 /// except it avoids creating a dependency on the whole crate.
  73 impl PpAnn for &dyn rustc_hir::intravisit::Map<'_> {
  74     fn nested(&self, state: &mut State<'_>, nested: Nested) {
  75         match nested {
  76             Nested::Item(id) => state.print_item(self.item(id.id)),
  77             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
  78             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
  79             Nested::Body(id) => state.print_expr(&self.body(id).value),
  80             Nested::BodyParamPat(id, i) => state.print_pat(&self.body(id).params[i].pat),
  81         }
  82     }
  83 }
  84
  85 pub struct State<'a> {
  86     pub s: pp::Printer,
  87     comments: Option<Comments<'a>>,
  88     ann: &'a (dyn PpAnn + 'a),
  89 }
  90
  91 impl<'a> State<'a> {
  92     pub fn print_node(&mut self, node: Node<'_>) {
  93         match node {
  94             Node::Param(a) => self.print_param(&a),
  95             Node::Item(a) => self.print_item(&a),
  96             Node::ForeignItem(a) => self.print_foreign_item(&a),
  97             Node::TraitItem(a) => self.print_trait_item(a),
  98             Node::ImplItem(a) => self.print_impl_item(a),
  99             Node::Variant(a) => self.print_variant(&a),
 100             Node::AnonConst(a) => self.print_anon_const(&a),
 101             Node::Expr(a) => self.print_expr(&a),
 102             Node::Stmt(a) => self.print_stmt(&a),
 103             Node::PathSegment(a) => self.print_path_segment(&a),
 104             Node::Ty(a) => self.print_type(&a),
 105             Node::TraitRef(a) => self.print_trait_ref(&a),
 106             Node::Binding(a) | Node::Pat(a) => self.print_pat(&a),
 107             Node::Arm(a) => self.print_arm(&a),
 108             Node::Block(a) => {
 109                 // Containing cbox, will be closed by print-block at `}`.
 110                 self.cbox(INDENT_UNIT);
 111                 // Head-ibox, will be closed by print-block after `{`.
 112                 self.ibox(0);
 113                 self.print_block(&a)
 114             }
 115             Node::Lifetime(a) => self.print_lifetime(&a),
 116             Node::Visibility(a) => self.print_visibility(&a),
 117             Node::GenericParam(_) => panic!("cannot print Node::GenericParam"),
 118             Node::Field(_) => panic!("cannot print StructField"),
 119             // These cases do not carry enough information in the
 120             // `hir_map` to reconstruct their full structure for pretty
 121             // printing.
 122             Node::Ctor(..) => panic!("cannot print isolated Ctor"),
 123             Node::Local(a) => self.print_local_decl(&a),
 124             Node::MacroDef(_) => panic!("cannot print MacroDef"),
 125             Node::Crate(..) => panic!("cannot print Crate"),
 126         }
 127     }
 128 }
 129
 130 impl std::ops::Deref for State<'_> {
 131     type Target = pp::Printer;
 132     fn deref(&self) -> &Self::Target {
 133         &self.s
 134     }
 135 }
 136
 137 impl std::ops::DerefMut for State<'_> {
 138     fn deref_mut(&mut self) -> &mut Self::Target {
 139         &mut self.s
 140     }
 141 }
 142
 143 impl<'a> PrintState<'a> for State<'a> {
 144     fn comments(&mut self) -> &mut Option<Comments<'a>> {
 145         &mut self.comments
 146     }
 147
 148     fn print_ident(&mut self, ident: Ident) {
 149         self.s.word(IdentPrinter::for_ast_ident(ident, ident.is_raw_guess()).to_string());
 150         self.ann.post(self, AnnNode::Name(&ident.name))
 151     }
 152
 153     fn print_generic_args(&mut self, _: &ast::GenericArgs, _colons_before_params: bool) {
 154         panic!("AST generic args printed by HIR pretty-printer");
 155     }
 156 }
 157
 158 pub const INDENT_UNIT: usize = 4;
 159
 160 /// Requires you to pass an input filename and reader so that
 161 /// it can scan the input text for comments to copy forward.
 162 pub fn print_crate<'a>(
 163     sm: &'a SourceMap,
 164     krate: &hir::Crate<'_>,
 165     filename: FileName,
 166     input: String,
 167     ann: &'a dyn PpAnn,
 168 ) -> String {
 169     let mut s = State::new_from_input(sm, filename, input, ann);
 170
 171     // When printing the AST, we sometimes need to inject `#[no_std]` here.
 172     // Since you can't compile the HIR, it's not necessary.
 173
 174     s.print_mod(&krate.item.module, &krate.item.attrs);
 175     s.print_remaining_comments();
 176     s.s.eof()
 177 }
 178
 179 impl<'a> State<'a> {
 180     pub fn new_from_input(
 181         sm: &'a SourceMap,
 182         filename: FileName,
 183         input: String,
 184         ann: &'a dyn PpAnn,
 185     ) -> State<'a> {
 186         State { s: pp::mk_printer(), comments: Some(Comments::new(sm, filename, input)), ann }
 187     }
 188 }
 189
 190 pub fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
 191 where
 192     F: FnOnce(&mut State<'_>),
 193 {
 194     let mut printer = State { s: pp::mk_printer(), comments: None, ann };
 195     f(&mut printer);
 196     printer.s.eof()
 197 }
 198
 199 pub fn visibility_qualified<S: Into<Cow<'static, str>>>(vis: &hir::Visibility<'_>, w: S) -> String {
 200     to_string(NO_ANN, |s| {
 201         s.print_visibility(vis);
 202         s.s.word(w)
 203     })
 204 }
 205
 206 pub fn generic_params_to_string(generic_params: &[GenericParam<'_>]) -> String {
 207     to_string(NO_ANN, |s| s.print_generic_params(generic_params))
 208 }
 209
 210 pub fn bounds_to_string<'b>(bounds: impl IntoIterator<Item = &'b hir::GenericBound<'b>>) -> String {
 211     to_string(NO_ANN, |s| s.print_bounds("", bounds))
 212 }
 213
 214 pub fn param_to_string(arg: &hir::Param<'_>) -> String {
 215     to_string(NO_ANN, |s| s.print_param(arg))
 216 }
 217
 218 pub fn ty_to_string(ty: &hir::Ty<'_>) -> String {
 219     to_string(NO_ANN, |s| s.print_type(ty))
 220 }
 221
 222 pub fn path_segment_to_string(segment: &hir::PathSegment<'_>) -> String {
 223     to_string(NO_ANN, |s| s.print_path_segment(segment))
 224 }
 225
 226 pub fn path_to_string(segment: &hir::Path<'_>) -> String {
 227     to_string(NO_ANN, |s| s.print_path(segment, false))
 228 }
 229
 230 pub fn fn_to_string(
 231     decl: &hir::FnDecl<'_>,
 232     header: hir::FnHeader,
 233     name: Option<Symbol>,
 234     generics: &hir::Generics<'_>,
 235     vis: &hir::Visibility<'_>,
 236     arg_names: &[Ident],
 237     body_id: Option<hir::BodyId>,
 238 ) -> String {
 239     to_string(NO_ANN, |s| s.print_fn(decl, header, name, generics, vis, arg_names, body_id))
 240 }
 241
 242 pub fn enum_def_to_string(
 243     enum_definition: &hir::EnumDef<'_>,
 244     generics: &hir::Generics<'_>,
 245     name: Symbol,
 246     span: rustc_span::Span,
 247     visibility: &hir::Visibility<'_>,
 248 ) -> String {
 249     to_string(NO_ANN, |s| s.print_enum_def(enum_definition, generics, name, span, visibility))
 250 }
 251
 252 impl<'a> State<'a> {
 253     pub fn cbox(&mut self, u: usize) {
 254         self.s.cbox(u);
 255     }
 256
 257     pub fn nbsp(&mut self) {
 258         self.s.word(" ")
 259     }
 260
 261     pub fn word_nbsp<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 262         self.s.word(w);
 263         self.nbsp()
 264     }
 265
 266     pub fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 267         let w = w.into();
 268         // outer-box is consistent
 269         self.cbox(INDENT_UNIT);
 270         // head-box is inconsistent
 271         self.ibox(w.len() + 1);
 272         // keyword that starts the head
 273         if !w.is_empty() {
 274             self.word_nbsp(w);
 275         }
 276     }
 277
 278     pub fn bopen(&mut self) {
 279         self.s.word("{");
 280         self.end(); // close the head-box
 281     }
 282
 283     pub fn bclose_maybe_open(&mut self, span: rustc_span::Span, close_box: bool) {
 284         self.maybe_print_comment(span.hi());
 285         self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
 286         self.s.word("}");
 287         if close_box {
 288             self.end(); // close the outer-box
 289         }
 290     }
 291
 292     pub fn bclose(&mut self, span: rustc_span::Span) {
 293         self.bclose_maybe_open(span, true)
 294     }
 295
 296     pub fn space_if_not_bol(&mut self) {
 297         if !self.s.is_beginning_of_line() {
 298             self.s.space();
 299         }
 300     }
 301
 302     pub fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
 303         if !self.s.is_beginning_of_line() {
 304             self.s.break_offset(n, off)
 305         } else {
 306             if off != 0 && self.s.last_token().is_hardbreak_tok() {
 307                 // We do something pretty sketchy here: tuck the nonzero
 308                 // offset-adjustment we were going to deposit along with the
 309                 // break into the previous hardbreak.
 310                 self.s.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 311             }
 312         }
 313     }
 314
 315     // Synthesizes a comment that was not textually present in the original source
 316     // file.
 317     pub fn synth_comment(&mut self, text: String) {
 318         self.s.word("/*");
 319         self.s.space();
 320         self.s.word(text);
 321         self.s.space();
 322         self.s.word("*/")
 323     }
 324
 325     pub fn commasep_cmnt<T, F, G>(&mut self, b: Breaks, elts: &[T], mut op: F, mut get_span: G)
 326     where
 327         F: FnMut(&mut State<'_>, &T),
 328         G: FnMut(&T) -> rustc_span::Span,
 329     {
 330         self.rbox(0, b);
 331         let len = elts.len();
 332         let mut i = 0;
 333         for elt in elts {
 334             self.maybe_print_comment(get_span(elt).hi());
 335             op(self, elt);
 336             i += 1;
 337             if i < len {
 338                 self.s.word(",");
 339                 self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()));
 340                 self.space_if_not_bol();
 341             }
 342         }
 343         self.end();
 344     }
 345
 346     pub fn commasep_exprs(&mut self, b: Breaks, exprs: &[hir::Expr<'_>]) {
 347         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
 348     }
 349
 350     pub fn print_mod(&mut self, _mod: &hir::Mod<'_>, attrs: &[ast::Attribute]) {
 351         self.print_inner_attributes(attrs);
 352         for &item_id in _mod.item_ids {
 353             self.ann.nested(self, Nested::Item(item_id));
 354         }
 355     }
 356
 357     pub fn print_foreign_mod(&mut self, nmod: &hir::ForeignMod<'_>, attrs: &[ast::Attribute]) {
 358         self.print_inner_attributes(attrs);
 359         for item in nmod.items {
 360             self.print_foreign_item(item);
 361         }
 362     }
 363
 364     pub fn print_opt_lifetime(&mut self, lifetime: &hir::Lifetime) {
 365         if !lifetime.is_elided() {
 366             self.print_lifetime(lifetime);
 367             self.nbsp();
 368         }
 369     }
 370
 371     pub fn print_type(&mut self, ty: &hir::Ty<'_>) {
 372         self.maybe_print_comment(ty.span.lo());
 373         self.ibox(0);
 374         match ty.kind {
 375             hir::TyKind::Slice(ref ty) => {
 376                 self.s.word("[");
 377                 self.print_type(&ty);
 378                 self.s.word("]");
 379             }
 380             hir::TyKind::Ptr(ref mt) => {
 381                 self.s.word("*");
 382                 self.print_mt(mt, true);
 383             }
 384             hir::TyKind::Rptr(ref lifetime, ref mt) => {
 385                 self.s.word("&");
 386                 self.print_opt_lifetime(lifetime);
 387                 self.print_mt(mt, false);
 388             }
 389             hir::TyKind::Never => {
 390                 self.s.word("!");
 391             }
 392             hir::TyKind::Tup(ref elts) => {
 393                 self.popen();
 394                 self.commasep(Inconsistent, &elts[..], |s, ty| s.print_type(&ty));
 395                 if elts.len() == 1 {
 396                     self.s.word(",");
 397                 }
 398                 self.pclose();
 399             }
 400             hir::TyKind::BareFn(ref f) => {
 401                 self.print_ty_fn(
 402                     f.abi,
 403                     f.unsafety,
 404                     &f.decl,
 405                     None,
 406                     &f.generic_params,
 407                     &f.param_names[..],
 408                 );
 409             }
 410             hir::TyKind::OpaqueDef(..) => self.s.word("/*impl Trait*/"),
 411             hir::TyKind::Path(ref qpath) => self.print_qpath(qpath, false),
 412             hir::TyKind::TraitObject(bounds, ref lifetime) => {
 413                 let mut first = true;
 414                 for bound in bounds {
 415                     if first {
 416                         first = false;
 417                     } else {
 418                         self.nbsp();
 419                         self.word_space("+");
 420                     }
 421                     self.print_poly_trait_ref(bound);
 422                 }
 423                 if !lifetime.is_elided() {
 424                     self.nbsp();
 425                     self.word_space("+");
 426                     self.print_lifetime(lifetime);
 427                 }
 428             }
 429             hir::TyKind::Array(ref ty, ref length) => {
 430                 self.s.word("[");
 431                 self.print_type(&ty);
 432                 self.s.word("; ");
 433                 self.print_anon_const(length);
 434                 self.s.word("]");
 435             }
 436             hir::TyKind::Typeof(ref e) => {
 437                 self.s.word("typeof(");
 438                 self.print_anon_const(e);
 439                 self.s.word(")");
 440             }
 441             hir::TyKind::Infer => {
 442                 self.s.word("_");
 443             }
 444             hir::TyKind::Err => {
 445                 self.popen();
 446                 self.s.word("/*ERROR*/");
 447                 self.pclose();
 448             }
 449         }
 450         self.end()
 451     }
 452
 453     pub fn print_foreign_item(&mut self, item: &hir::ForeignItem<'_>) {
 454         self.hardbreak_if_not_bol();
 455         self.maybe_print_comment(item.span.lo());
 456         self.print_outer_attributes(&item.attrs);
 457         match item.kind {
 458             hir::ForeignItemKind::Fn(ref decl, ref arg_names, ref generics) => {
 459                 self.head("");
 460                 self.print_fn(
 461                     decl,
 462                     hir::FnHeader {
 463                         unsafety: hir::Unsafety::Normal,
 464                         constness: hir::Constness::NotConst,
 465                         abi: Abi::Rust,
 466                         asyncness: hir::IsAsync::NotAsync,
 467                     },
 468                     Some(item.ident.name),
 469                     generics,
 470                     &item.vis,
 471                     arg_names,
 472                     None,
 473                 );
 474                 self.end(); // end head-ibox
 475                 self.s.word(";");
 476                 self.end() // end the outer fn box
 477             }
 478             hir::ForeignItemKind::Static(ref t, m) => {
 479                 self.head(visibility_qualified(&item.vis, "static"));
 480                 if m == hir::Mutability::Mut {
 481                     self.word_space("mut");
 482                 }
 483                 self.print_ident(item.ident);
 484                 self.word_space(":");
 485                 self.print_type(&t);
 486                 self.s.word(";");
 487                 self.end(); // end the head-ibox
 488                 self.end() // end the outer cbox
 489             }
 490             hir::ForeignItemKind::Type => {
 491                 self.head(visibility_qualified(&item.vis, "type"));
 492                 self.print_ident(item.ident);
 493                 self.s.word(";");
 494                 self.end(); // end the head-ibox
 495                 self.end() // end the outer cbox
 496             }
 497         }
 498     }
 499
 500     fn print_associated_const(
 501         &mut self,
 502         ident: Ident,
 503         ty: &hir::Ty<'_>,
 504         default: Option<hir::BodyId>,
 505         vis: &hir::Visibility<'_>,
 506     ) {
 507         self.s.word(visibility_qualified(vis, ""));
 508         self.word_space("const");
 509         self.print_ident(ident);
 510         self.word_space(":");
 511         self.print_type(ty);
 512         if let Some(expr) = default {
 513             self.s.space();
 514             self.word_space("=");
 515             self.ann.nested(self, Nested::Body(expr));
 516         }
 517         self.s.word(";")
 518     }
 519
 520     fn print_associated_type(
 521         &mut self,
 522         ident: Ident,
 523         generics: &hir::Generics<'_>,
 524         bounds: Option<hir::GenericBounds<'_>>,
 525         ty: Option<&hir::Ty<'_>>,
 526     ) {
 527         self.word_space("type");
 528         self.print_ident(ident);
 529         self.print_generic_params(&generics.params);
 530         if let Some(bounds) = bounds {
 531             self.print_bounds(":", bounds);
 532         }
 533         self.print_where_clause(&generics.where_clause);
 534         if let Some(ty) = ty {
 535             self.s.space();
 536             self.word_space("=");
 537             self.print_type(ty);
 538         }
 539         self.s.word(";")
 540     }
 541
 542     fn print_item_type(
 543         &mut self,
 544         item: &hir::Item<'_>,
 545         generics: &hir::Generics<'_>,
 546         inner: impl Fn(&mut Self),
 547     ) {
 548         self.head(visibility_qualified(&item.vis, "type"));
 549         self.print_ident(item.ident);
 550         self.print_generic_params(&generics.params);
 551         self.end(); // end the inner ibox
 552
 553         self.print_where_clause(&generics.where_clause);
 554         self.s.space();
 555         inner(self);
 556         self.s.word(";");
 557         self.end(); // end the outer ibox
 558     }
 559
 560     /// Pretty-print an item
 561     pub fn print_item(&mut self, item: &hir::Item<'_>) {
 562         self.hardbreak_if_not_bol();
 563         self.maybe_print_comment(item.span.lo());
 564         self.print_outer_attributes(&item.attrs);
 565         self.ann.pre(self, AnnNode::Item(item));
 566         match item.kind {
 567             hir::ItemKind::ExternCrate(orig_name) => {
 568                 self.head(visibility_qualified(&item.vis, "extern crate"));
 569                 if let Some(orig_name) = orig_name {
 570                     self.print_name(orig_name);
 571                     self.s.space();
 572                     self.s.word("as");
 573                     self.s.space();
 574                 }
 575                 self.print_ident(item.ident);
 576                 self.s.word(";");
 577                 self.end(); // end inner head-block
 578                 self.end(); // end outer head-block
 579             }
 580             hir::ItemKind::Use(ref path, kind) => {
 581                 self.head(visibility_qualified(&item.vis, "use"));
 582                 self.print_path(path, false);
 583
 584                 match kind {
 585                     hir::UseKind::Single => {
 586                         if path.segments.last().unwrap().ident != item.ident {
 587                             self.s.space();
 588                             self.word_space("as");
 589                             self.print_ident(item.ident);
 590                         }
 591                         self.s.word(";");
 592                     }
 593                     hir::UseKind::Glob => self.s.word("::*;"),
 594                     hir::UseKind::ListStem => self.s.word("::{};"),
 595                 }
 596                 self.end(); // end inner head-block
 597                 self.end(); // end outer head-block
 598             }
 599             hir::ItemKind::Static(ref ty, m, expr) => {
 600                 self.head(visibility_qualified(&item.vis, "static"));
 601                 if m == hir::Mutability::Mut {
 602                     self.word_space("mut");
 603                 }
 604                 self.print_ident(item.ident);
 605                 self.word_space(":");
 606                 self.print_type(&ty);
 607                 self.s.space();
 608                 self.end(); // end the head-ibox
 609
 610                 self.word_space("=");
 611                 self.ann.nested(self, Nested::Body(expr));
 612                 self.s.word(";");
 613                 self.end(); // end the outer cbox
 614             }
 615             hir::ItemKind::Const(ref ty, expr) => {
 616                 self.head(visibility_qualified(&item.vis, "const"));
 617                 self.print_ident(item.ident);
 618                 self.word_space(":");
 619                 self.print_type(&ty);
 620                 self.s.space();
 621                 self.end(); // end the head-ibox
 622
 623                 self.word_space("=");
 624                 self.ann.nested(self, Nested::Body(expr));
 625                 self.s.word(";");
 626                 self.end(); // end the outer cbox
 627             }
 628             hir::ItemKind::Fn(ref sig, ref param_names, body) => {
 629                 self.head("");
 630                 self.print_fn(
 631                     &sig.decl,
 632                     sig.header,
 633                     Some(item.ident.name),
 634                     param_names,
 635                     &item.vis,
 636                     &[],
 637                     Some(body),
 638                 );
 639                 self.s.word(" ");
 640                 self.end(); // need to close a box
 641                 self.end(); // need to close a box
 642                 self.ann.nested(self, Nested::Body(body));
 643             }
 644             hir::ItemKind::Mod(ref _mod) => {
 645                 self.head(visibility_qualified(&item.vis, "mod"));
 646                 self.print_ident(item.ident);
 647                 self.nbsp();
 648                 self.bopen();
 649                 self.print_mod(_mod, &item.attrs);
 650                 self.bclose(item.span);
 651             }
 652             hir::ItemKind::ForeignMod(ref nmod) => {
 653                 self.head("extern");
 654                 self.word_nbsp(nmod.abi.to_string());
 655                 self.bopen();
 656                 self.print_foreign_mod(nmod, &item.attrs);
 657                 self.bclose(item.span);
 658             }
 659             hir::ItemKind::GlobalAsm(ref ga) => {
 660                 self.head(visibility_qualified(&item.vis, "global asm"));
 661                 self.s.word(ga.asm.to_string());
 662                 self.end()
 663             }
 664             hir::ItemKind::TyAlias(ref ty, ref generics) => {
 665                 self.print_item_type(item, &generics, |state| {
 666                     state.word_space("=");
 667                     state.print_type(&ty);
 668                 });
 669             }
 670             hir::ItemKind::OpaqueTy(ref opaque_ty) => {
 671                 self.print_item_type(item, &opaque_ty.generics, |state| {
 672                     let mut real_bounds = Vec::with_capacity(opaque_ty.bounds.len());
 673                     for b in opaque_ty.bounds.iter() {
 674                         if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 675                             state.s.space();
 676                             state.word_space("for ?");
 677                             state.print_trait_ref(&ptr.trait_ref);
 678                         } else {
 679                             real_bounds.push(b);
 680                         }
 681                     }
 682                     state.print_bounds("= impl", real_bounds);
 683                 });
 684             }
 685             hir::ItemKind::Enum(ref enum_definition, ref params) => {
 686                 self.print_enum_def(enum_definition, params, item.ident.name, item.span, &item.vis);
 687             }
 688             hir::ItemKind::Struct(ref struct_def, ref generics) => {
 689                 self.head(visibility_qualified(&item.vis, "struct"));
 690                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
 691             }
 692             hir::ItemKind::Union(ref struct_def, ref generics) => {
 693                 self.head(visibility_qualified(&item.vis, "union"));
 694                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
 695             }
 696             hir::ItemKind::Impl {
 697                 unsafety,
 698                 polarity,
 699                 defaultness,
 700                 constness,
 701                 defaultness_span: _,
 702                 ref generics,
 703                 ref of_trait,
 704                 ref self_ty,
 705                 items,
 706             } => {
 707                 self.head("");
 708                 self.print_visibility(&item.vis);
 709                 self.print_defaultness(defaultness);
 710                 self.print_unsafety(unsafety);
 711                 self.word_nbsp("impl");
 712
 713                 if !generics.params.is_empty() {
 714                     self.print_generic_params(&generics.params);
 715                     self.s.space();
 716                 }
 717
 718                 if constness == hir::Constness::Const {
 719                     self.word_nbsp("const");
 720                 }
 721
 722                 if let hir::ImplPolarity::Negative(_) = polarity {
 723                     self.s.word("!");
 724                 }
 725
 726                 if let Some(ref t) = of_trait {
 727                     self.print_trait_ref(t);
 728                     self.s.space();
 729                     self.word_space("for");
 730                 }
 731
 732                 self.print_type(&self_ty);
 733                 self.print_where_clause(&generics.where_clause);
 734
 735                 self.s.space();
 736                 self.bopen();
 737                 self.print_inner_attributes(&item.attrs);
 738                 for impl_item in items {
 739                     self.ann.nested(self, Nested::ImplItem(impl_item.id));
 740                 }
 741                 self.bclose(item.span);
 742             }
 743             hir::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, trait_items) => {
 744                 self.head("");
 745                 self.print_visibility(&item.vis);
 746                 self.print_is_auto(is_auto);
 747                 self.print_unsafety(unsafety);
 748                 self.word_nbsp("trait");
 749                 self.print_ident(item.ident);
 750                 self.print_generic_params(&generics.params);
 751                 let mut real_bounds = Vec::with_capacity(bounds.len());
 752                 for b in bounds.iter() {
 753                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 754                         self.s.space();
 755                         self.word_space("for ?");
 756                         self.print_trait_ref(&ptr.trait_ref);
 757                     } else {
 758                         real_bounds.push(b);
 759                     }
 760                 }
 761                 self.print_bounds(":", real_bounds);
 762                 self.print_where_clause(&generics.where_clause);
 763                 self.s.word(" ");
 764                 self.bopen();
 765                 for trait_item in trait_items {
 766                     self.ann.nested(self, Nested::TraitItem(trait_item.id));
 767                 }
 768                 self.bclose(item.span);
 769             }
 770             hir::ItemKind::TraitAlias(ref generics, ref bounds) => {
 771                 self.head("");
 772                 self.print_visibility(&item.vis);
 773                 self.word_nbsp("trait");
 774                 self.print_ident(item.ident);
 775                 self.print_generic_params(&generics.params);
 776                 let mut real_bounds = Vec::with_capacity(bounds.len());
 777                 // FIXME(durka) this seems to be some quite outdated syntax
 778                 for b in bounds.iter() {
 779                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 780                         self.s.space();
 781                         self.word_space("for ?");
 782                         self.print_trait_ref(&ptr.trait_ref);
 783                     } else {
 784                         real_bounds.push(b);
 785                     }
 786                 }
 787                 self.nbsp();
 788                 self.print_bounds("=", real_bounds);
 789                 self.print_where_clause(&generics.where_clause);
 790                 self.s.word(";");
 791             }
 792         }
 793         self.ann.post(self, AnnNode::Item(item))
 794     }
 795
 796     pub fn print_trait_ref(&mut self, t: &hir::TraitRef<'_>) {
 797         self.print_path(&t.path, false)
 798     }
 799
 800     fn print_formal_generic_params(&mut self, generic_params: &[hir::GenericParam<'_>]) {
 801         if !generic_params.is_empty() {
 802             self.s.word("for");
 803             self.print_generic_params(generic_params);
 804             self.nbsp();
 805         }
 806     }
 807
 808     fn print_poly_trait_ref(&mut self, t: &hir::PolyTraitRef<'_>) {
 809         self.print_formal_generic_params(&t.bound_generic_params);
 810         self.print_trait_ref(&t.trait_ref)
 811     }
 812
 813     pub fn print_enum_def(
 814         &mut self,
 815         enum_definition: &hir::EnumDef<'_>,
 816         generics: &hir::Generics<'_>,
 817         name: Symbol,
 818         span: rustc_span::Span,
 819         visibility: &hir::Visibility<'_>,
 820     ) {
 821         self.head(visibility_qualified(visibility, "enum"));
 822         self.print_name(name);
 823         self.print_generic_params(&generics.params);
 824         self.print_where_clause(&generics.where_clause);
 825         self.s.space();
 826         self.print_variants(&enum_definition.variants, span)
 827     }
 828
 829     pub fn print_variants(&mut self, variants: &[hir::Variant<'_>], span: rustc_span::Span) {
 830         self.bopen();
 831         for v in variants {
 832             self.space_if_not_bol();
 833             self.maybe_print_comment(v.span.lo());
 834             self.print_outer_attributes(&v.attrs);
 835             self.ibox(INDENT_UNIT);
 836             self.print_variant(v);
 837             self.s.word(",");
 838             self.end();
 839             self.maybe_print_trailing_comment(v.span, None);
 840         }
 841         self.bclose(span)
 842     }
 843
 844     pub fn print_visibility(&mut self, vis: &hir::Visibility<'_>) {
 845         match vis.node {
 846             hir::VisibilityKind::Public => self.word_nbsp("pub"),
 847             hir::VisibilityKind::Crate(ast::CrateSugar::JustCrate) => self.word_nbsp("crate"),
 848             hir::VisibilityKind::Crate(ast::CrateSugar::PubCrate) => self.word_nbsp("pub(crate)"),
 849             hir::VisibilityKind::Restricted { ref path, .. } => {
 850                 self.s.word("pub(");
 851                 if path.segments.len() == 1 && path.segments[0].ident.name == kw::Super {
 852                     // Special case: `super` can print like `pub(super)`.
 853                     self.s.word("super");
 854                 } else {
 855                     // Everything else requires `in` at present.
 856                     self.word_nbsp("in");
 857                     self.print_path(path, false);
 858                 }
 859                 self.word_nbsp(")");
 860             }
 861             hir::VisibilityKind::Inherited => (),
 862         }
 863     }
 864
 865     pub fn print_defaultness(&mut self, defaultness: hir::Defaultness) {
 866         match defaultness {
 867             hir::Defaultness::Default { .. } => self.word_nbsp("default"),
 868             hir::Defaultness::Final => (),
 869         }
 870     }
 871
 872     pub fn print_struct(
 873         &mut self,
 874         struct_def: &hir::VariantData<'_>,
 875         generics: &hir::Generics<'_>,
 876         name: Symbol,
 877         span: rustc_span::Span,
 878         print_finalizer: bool,
 879     ) {
 880         self.print_name(name);
 881         self.print_generic_params(&generics.params);
 882         match struct_def {
 883             hir::VariantData::Tuple(..) | hir::VariantData::Unit(..) => {
 884                 if let hir::VariantData::Tuple(..) = struct_def {
 885                     self.popen();
 886                     self.commasep(Inconsistent, struct_def.fields(), |s, field| {
 887                         s.maybe_print_comment(field.span.lo());
 888                         s.print_outer_attributes(&field.attrs);
 889                         s.print_visibility(&field.vis);
 890                         s.print_type(&field.ty)
 891                     });
 892                     self.pclose();
 893                 }
 894                 self.print_where_clause(&generics.where_clause);
 895                 if print_finalizer {
 896                     self.s.word(";");
 897                 }
 898                 self.end();
 899                 self.end() // close the outer-box
 900             }
 901             hir::VariantData::Struct(..) => {
 902                 self.print_where_clause(&generics.where_clause);
 903                 self.nbsp();
 904                 self.bopen();
 905                 self.hardbreak_if_not_bol();
 906
 907                 for field in struct_def.fields() {
 908                     self.hardbreak_if_not_bol();
 909                     self.maybe_print_comment(field.span.lo());
 910                     self.print_outer_attributes(&field.attrs);
 911                     self.print_visibility(&field.vis);
 912                     self.print_ident(field.ident);
 913                     self.word_nbsp(":");
 914                     self.print_type(&field.ty);
 915                     self.s.word(",");
 916                 }
 917
 918                 self.bclose(span)
 919             }
 920         }
 921     }
 922
 923     pub fn print_variant(&mut self, v: &hir::Variant<'_>) {
 924         self.head("");
 925         let generics = hir::Generics::empty();
 926         self.print_struct(&v.data, &generics, v.ident.name, v.span, false);
 927         if let Some(ref d) = v.disr_expr {
 928             self.s.space();
 929             self.word_space("=");
 930             self.print_anon_const(d);
 931         }
 932     }
 933     pub fn print_method_sig(
 934         &mut self,
 935         ident: Ident,
 936         m: &hir::FnSig<'_>,
 937         generics: &hir::Generics<'_>,
 938         vis: &hir::Visibility<'_>,
 939         arg_names: &[Ident],
 940         body_id: Option<hir::BodyId>,
 941     ) {
 942         self.print_fn(&m.decl, m.header, Some(ident.name), generics, vis, arg_names, body_id)
 943     }
 944
 945     pub fn print_trait_item(&mut self, ti: &hir::TraitItem<'_>) {
 946         self.ann.pre(self, AnnNode::SubItem(ti.hir_id));
 947         self.hardbreak_if_not_bol();
 948         self.maybe_print_comment(ti.span.lo());
 949         self.print_outer_attributes(&ti.attrs);
 950         match ti.kind {
 951             hir::TraitItemKind::Const(ref ty, default) => {
 952                 let vis =
 953                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
 954                 self.print_associated_const(ti.ident, &ty, default, &vis);
 955             }
 956             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(ref arg_names)) => {
 957                 let vis =
 958                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
 959                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, arg_names, None);
 960                 self.s.word(";");
 961             }
 962             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
 963                 let vis =
 964                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
 965                 self.head("");
 966                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, &[], Some(body));
 967                 self.nbsp();
 968                 self.end(); // need to close a box
 969                 self.end(); // need to close a box
 970                 self.ann.nested(self, Nested::Body(body));
 971             }
 972             hir::TraitItemKind::Type(ref bounds, ref default) => {
 973                 self.print_associated_type(
 974                     ti.ident,
 975                     &ti.generics,
 976                     Some(bounds),
 977                     default.as_ref().map(|ty| &**ty),
 978                 );
 979             }
 980         }
 981         self.ann.post(self, AnnNode::SubItem(ti.hir_id))
 982     }
 983
 984     pub fn print_impl_item(&mut self, ii: &hir::ImplItem<'_>) {
 985         self.ann.pre(self, AnnNode::SubItem(ii.hir_id));
 986         self.hardbreak_if_not_bol();
 987         self.maybe_print_comment(ii.span.lo());
 988         self.print_outer_attributes(&ii.attrs);
 989         self.print_defaultness(ii.defaultness);
 990
 991         match ii.kind {
 992             hir::ImplItemKind::Const(ref ty, expr) => {
 993                 self.print_associated_const(ii.ident, &ty, Some(expr), &ii.vis);
 994             }
 995             hir::ImplItemKind::Fn(ref sig, body) => {
 996                 self.head("");
 997                 self.print_method_sig(ii.ident, sig, &ii.generics, &ii.vis, &[], Some(body));
 998                 self.nbsp();
 999                 self.end(); // need to close a box
1000                 self.end(); // need to close a box
1001                 self.ann.nested(self, Nested::Body(body));
1002             }
1003             hir::ImplItemKind::TyAlias(ref ty) => {
1004                 self.print_associated_type(ii.ident, &ii.generics, None, Some(ty));
1005             }
1006         }
1007         self.ann.post(self, AnnNode::SubItem(ii.hir_id))
1008     }
1009
1010     pub fn print_local(&mut self, init: Option<&hir::Expr<'_>>, decl: impl Fn(&mut Self)) {
1011         self.space_if_not_bol();
1012         self.ibox(INDENT_UNIT);
1013         self.word_nbsp("let");
1014
1015         self.ibox(INDENT_UNIT);
1016         decl(self);
1017         self.end();
1018
1019         if let Some(ref init) = init {
1020             self.nbsp();
1021             self.word_space("=");
1022             self.print_expr(&init);
1023         }
1024         self.end()
1025     }
1026
1027     pub fn print_stmt(&mut self, st: &hir::Stmt<'_>) {
1028         self.maybe_print_comment(st.span.lo());
1029         match st.kind {
1030             hir::StmtKind::Local(ref loc) => {
1031                 self.print_local(loc.init.as_deref(), |this| this.print_local_decl(&loc));
1032             }
1033             hir::StmtKind::Item(item) => self.ann.nested(self, Nested::Item(item)),
1034             hir::StmtKind::Expr(ref expr) => {
1035                 self.space_if_not_bol();
1036                 self.print_expr(&expr);
1037             }
1038             hir::StmtKind::Semi(ref expr) => {
1039                 self.space_if_not_bol();
1040                 self.print_expr(&expr);
1041                 self.s.word(";");
1042             }
1043         }
1044         if stmt_ends_with_semi(&st.kind) {
1045             self.s.word(";");
1046         }
1047         self.maybe_print_trailing_comment(st.span, None)
1048     }
1049
1050     pub fn print_block(&mut self, blk: &hir::Block<'_>) {
1051         self.print_block_with_attrs(blk, &[])
1052     }
1053
1054     pub fn print_block_unclosed(&mut self, blk: &hir::Block<'_>) {
1055         self.print_block_maybe_unclosed(blk, &[], false)
1056     }
1057
1058     pub fn print_block_with_attrs(&mut self, blk: &hir::Block<'_>, attrs: &[ast::Attribute]) {
1059         self.print_block_maybe_unclosed(blk, attrs, true)
1060     }
1061
1062     pub fn print_block_maybe_unclosed(
1063         &mut self,
1064         blk: &hir::Block<'_>,
1065         attrs: &[ast::Attribute],
1066         close_box: bool,
1067     ) {
1068         match blk.rules {
1069             hir::BlockCheckMode::UnsafeBlock(..) => self.word_space("unsafe"),
1070             hir::BlockCheckMode::PushUnsafeBlock(..) => self.word_space("push_unsafe"),
1071             hir::BlockCheckMode::PopUnsafeBlock(..) => self.word_space("pop_unsafe"),
1072             hir::BlockCheckMode::DefaultBlock => (),
1073         }
1074         self.maybe_print_comment(blk.span.lo());
1075         self.ann.pre(self, AnnNode::Block(blk));
1076         self.bopen();
1077
1078         self.print_inner_attributes(attrs);
1079
1080         for st in blk.stmts {
1081             self.print_stmt(st);
1082         }
1083         if let Some(ref expr) = blk.expr {
1084             self.space_if_not_bol();
1085             self.print_expr(&expr);
1086             self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
1087         }
1088         self.bclose_maybe_open(blk.span, close_box);
1089         self.ann.post(self, AnnNode::Block(blk))
1090     }
1091
1092     pub fn print_anon_const(&mut self, constant: &hir::AnonConst) {
1093         self.ann.nested(self, Nested::Body(constant.body))
1094     }
1095
1096     fn print_call_post(&mut self, args: &[hir::Expr<'_>]) {
1097         self.popen();
1098         self.commasep_exprs(Inconsistent, args);
1099         self.pclose()
1100     }
1101
1102     pub fn print_expr_maybe_paren(&mut self, expr: &hir::Expr<'_>, prec: i8) {
1103         let needs_par = expr.precedence().order() < prec;
1104         if needs_par {
1105             self.popen();
1106         }
1107         self.print_expr(expr);
1108         if needs_par {
1109             self.pclose();
1110         }
1111     }
1112
1113     /// Print an expr using syntax that's acceptable in a condition position, such as the `cond` in
1114     /// `if cond { ... }`.
1115     pub fn print_expr_as_cond(&mut self, expr: &hir::Expr<'_>) {
1116         let needs_par = match expr.kind {
1117             // These cases need parens due to the parse error observed in #26461: `if return {}`
1118             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1119             hir::ExprKind::Closure(..) | hir::ExprKind::Ret(..) | hir::ExprKind::Break(..) => true,
1120
1121             _ => contains_exterior_struct_lit(expr),
1122         };
1123
1124         if needs_par {
1125             self.popen();
1126         }
1127         self.print_expr(expr);
1128         if needs_par {
1129             self.pclose();
1130         }
1131     }
1132
1133     fn print_expr_vec(&mut self, exprs: &[hir::Expr<'_>]) {
1134         self.ibox(INDENT_UNIT);
1135         self.s.word("[");
1136         self.commasep_exprs(Inconsistent, exprs);
1137         self.s.word("]");
1138         self.end()
1139     }
1140
1141     fn print_expr_repeat(&mut self, element: &hir::Expr<'_>, count: &hir::AnonConst) {
1142         self.ibox(INDENT_UNIT);
1143         self.s.word("[");
1144         self.print_expr(element);
1145         self.word_space(";");
1146         self.print_anon_const(count);
1147         self.s.word("]");
1148         self.end()
1149     }
1150
1151     fn print_expr_struct(
1152         &mut self,
1153         qpath: &hir::QPath<'_>,
1154         fields: &[hir::Field<'_>],
1155         wth: &Option<&hir::Expr<'_>>,
1156     ) {
1157         self.print_qpath(qpath, true);
1158         self.s.word("{");
1159         self.commasep_cmnt(
1160             Consistent,
1161             &fields[..],
1162             |s, field| {
1163                 s.ibox(INDENT_UNIT);
1164                 if !field.is_shorthand {
1165                     s.print_ident(field.ident);
1166                     s.word_space(":");
1167                 }
1168                 s.print_expr(&field.expr);
1169                 s.end()
1170             },
1171             |f| f.span,
1172         );
1173         match *wth {
1174             Some(ref expr) => {
1175                 self.ibox(INDENT_UNIT);
1176                 if !fields.is_empty() {
1177                     self.s.word(",");
1178                     self.s.space();
1179                 }
1180                 self.s.word("..");
1181                 self.print_expr(&expr);
1182                 self.end();
1183             }
1184             _ => {
1185                 if !fields.is_empty() {
1186                     self.s.word(",")
1187                 }
1188             }
1189         }
1190         self.s.word("}");
1191     }
1192
1193     fn print_expr_tup(&mut self, exprs: &[hir::Expr<'_>]) {
1194         self.popen();
1195         self.commasep_exprs(Inconsistent, exprs);
1196         if exprs.len() == 1 {
1197             self.s.word(",");
1198         }
1199         self.pclose()
1200     }
1201
1202     fn print_expr_call(&mut self, func: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
1203         let prec = match func.kind {
1204             hir::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1205             _ => parser::PREC_POSTFIX,
1206         };
1207
1208         self.print_expr_maybe_paren(func, prec);
1209         self.print_call_post(args)
1210     }
1211
1212     fn print_expr_method_call(&mut self, segment: &hir::PathSegment<'_>, args: &[hir::Expr<'_>]) {
1213         let base_args = &args[1..];
1214         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
1215         self.s.word(".");
1216         self.print_ident(segment.ident);
1217
1218         let generic_args = segment.generic_args();
1219         if !generic_args.args.is_empty() || !generic_args.bindings.is_empty() {
1220             self.print_generic_args(generic_args, segment.infer_args, true);
1221         }
1222
1223         self.print_call_post(base_args)
1224     }
1225
1226     fn print_expr_binary(&mut self, op: hir::BinOp, lhs: &hir::Expr<'_>, rhs: &hir::Expr<'_>) {
1227         let assoc_op = bin_op_to_assoc_op(op.node);
1228         let prec = assoc_op.precedence() as i8;
1229         let fixity = assoc_op.fixity();
1230
1231         let (left_prec, right_prec) = match fixity {
1232             Fixity::Left => (prec, prec + 1),
1233             Fixity::Right => (prec + 1, prec),
1234             Fixity::None => (prec + 1, prec + 1),
1235         };
1236
1237         let left_prec = match (&lhs.kind, op.node) {
1238             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1239             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1240             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1241             (&hir::ExprKind::Cast { .. }, hir::BinOpKind::Lt | hir::BinOpKind::Shl) => {
1242                 parser::PREC_FORCE_PAREN
1243             }
1244             _ => left_prec,
1245         };
1246
1247         self.print_expr_maybe_paren(lhs, left_prec);
1248         self.s.space();
1249         self.word_space(op.node.as_str());
1250         self.print_expr_maybe_paren(rhs, right_prec)
1251     }
1252
1253     fn print_expr_unary(&mut self, op: hir::UnOp, expr: &hir::Expr<'_>) {
1254         self.s.word(op.as_str());
1255         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1256     }
1257
1258     fn print_expr_addr_of(
1259         &mut self,
1260         kind: hir::BorrowKind,
1261         mutability: hir::Mutability,
1262         expr: &hir::Expr<'_>,
1263     ) {
1264         self.s.word("&");
1265         match kind {
1266             hir::BorrowKind::Ref => self.print_mutability(mutability, false),
1267             hir::BorrowKind::Raw => {
1268                 self.word_nbsp("raw");
1269                 self.print_mutability(mutability, true);
1270             }
1271         }
1272         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1273     }
1274
1275     fn print_literal(&mut self, lit: &hir::Lit) {
1276         self.maybe_print_comment(lit.span.lo());
1277         self.word(lit.node.to_lit_token().to_string())
1278     }
1279
1280     pub fn print_expr(&mut self, expr: &hir::Expr<'_>) {
1281         self.maybe_print_comment(expr.span.lo());
1282         self.print_outer_attributes(&expr.attrs);
1283         self.ibox(INDENT_UNIT);
1284         self.ann.pre(self, AnnNode::Expr(expr));
1285         match expr.kind {
1286             hir::ExprKind::Box(ref expr) => {
1287                 self.word_space("box");
1288                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX);
1289             }
1290             hir::ExprKind::Array(ref exprs) => {
1291                 self.print_expr_vec(exprs);
1292             }
1293             hir::ExprKind::Repeat(ref element, ref count) => {
1294                 self.print_expr_repeat(&element, count);
1295             }
1296             hir::ExprKind::Struct(ref qpath, fields, ref wth) => {
1297                 self.print_expr_struct(qpath, fields, wth);
1298             }
1299             hir::ExprKind::Tup(ref exprs) => {
1300                 self.print_expr_tup(exprs);
1301             }
1302             hir::ExprKind::Call(ref func, ref args) => {
1303                 self.print_expr_call(&func, args);
1304             }
1305             hir::ExprKind::MethodCall(ref segment, _, ref args, _) => {
1306                 self.print_expr_method_call(segment, args);
1307             }
1308             hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
1309                 self.print_expr_binary(op, &lhs, &rhs);
1310             }
1311             hir::ExprKind::Unary(op, ref expr) => {
1312                 self.print_expr_unary(op, &expr);
1313             }
1314             hir::ExprKind::AddrOf(k, m, ref expr) => {
1315                 self.print_expr_addr_of(k, m, &expr);
1316             }
1317             hir::ExprKind::Lit(ref lit) => {
1318                 self.print_literal(&lit);
1319             }
1320             hir::ExprKind::Cast(ref expr, ref ty) => {
1321                 let prec = AssocOp::As.precedence() as i8;
1322                 self.print_expr_maybe_paren(&expr, prec);
1323                 self.s.space();
1324                 self.word_space("as");
1325                 self.print_type(&ty);
1326             }
1327             hir::ExprKind::Type(ref expr, ref ty) => {
1328                 let prec = AssocOp::Colon.precedence() as i8;
1329                 self.print_expr_maybe_paren(&expr, prec);
1330                 self.word_space(":");
1331                 self.print_type(&ty);
1332             }
1333             hir::ExprKind::DropTemps(ref init) => {
1334                 // Print `{`:
1335                 self.cbox(INDENT_UNIT);
1336                 self.ibox(0);
1337                 self.bopen();
1338
1339                 // Print `let _t = $init;`:
1340                 let temp = Ident::from_str("_t");
1341                 self.print_local(Some(init), |this| this.print_ident(temp));
1342                 self.s.word(";");
1343
1344                 // Print `_t`:
1345                 self.space_if_not_bol();
1346                 self.print_ident(temp);
1347
1348                 // Print `}`:
1349                 self.bclose_maybe_open(expr.span, true);
1350             }
1351             hir::ExprKind::Loop(ref blk, opt_label, _) => {
1352                 if let Some(label) = opt_label {
1353                     self.print_ident(label.ident);
1354                     self.word_space(":");
1355                 }
1356                 self.head("loop");
1357                 self.s.space();
1358                 self.print_block(&blk);
1359             }
1360             hir::ExprKind::Match(ref expr, arms, _) => {
1361                 self.cbox(INDENT_UNIT);
1362                 self.ibox(INDENT_UNIT);
1363                 self.word_nbsp("match");
1364                 self.print_expr_as_cond(&expr);
1365                 self.s.space();
1366                 self.bopen();
1367                 for arm in arms {
1368                     self.print_arm(arm);
1369                 }
1370                 self.bclose(expr.span);
1371             }
1372             hir::ExprKind::Closure(capture_clause, ref decl, body, _fn_decl_span, _gen) => {
1373                 self.print_capture_clause(capture_clause);
1374
1375                 self.print_closure_params(&decl, body);
1376                 self.s.space();
1377
1378                 // This is a bare expression.
1379                 self.ann.nested(self, Nested::Body(body));
1380                 self.end(); // need to close a box
1381
1382                 // A box will be closed by `print_expr`, but we didn't want an overall
1383                 // wrapper so we closed the corresponding opening. so create an
1384                 // empty box to satisfy the close.
1385                 self.ibox(0);
1386             }
1387             hir::ExprKind::Block(ref blk, opt_label) => {
1388                 if let Some(label) = opt_label {
1389                     self.print_ident(label.ident);
1390                     self.word_space(":");
1391                 }
1392                 // containing cbox, will be closed by print-block at `}`
1393                 self.cbox(INDENT_UNIT);
1394                 // head-box, will be closed by print-block after `{`
1395                 self.ibox(0);
1396                 self.print_block(&blk);
1397             }
1398             hir::ExprKind::Assign(ref lhs, ref rhs, _) => {
1399                 let prec = AssocOp::Assign.precedence() as i8;
1400                 self.print_expr_maybe_paren(&lhs, prec + 1);
1401                 self.s.space();
1402                 self.word_space("=");
1403                 self.print_expr_maybe_paren(&rhs, prec);
1404             }
1405             hir::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
1406                 let prec = AssocOp::Assign.precedence() as i8;
1407                 self.print_expr_maybe_paren(&lhs, prec + 1);
1408                 self.s.space();
1409                 self.s.word(op.node.as_str());
1410                 self.word_space("=");
1411                 self.print_expr_maybe_paren(&rhs, prec);
1412             }
1413             hir::ExprKind::Field(ref expr, ident) => {
1414                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
1415                 self.s.word(".");
1416                 self.print_ident(ident);
1417             }
1418             hir::ExprKind::Index(ref expr, ref index) => {
1419                 self.print_expr_maybe_paren(&expr, parser::PREC_POSTFIX);
1420                 self.s.word("[");
1421                 self.print_expr(&index);
1422                 self.s.word("]");
1423             }
1424             hir::ExprKind::Path(ref qpath) => self.print_qpath(qpath, true),
1425             hir::ExprKind::Break(destination, ref opt_expr) => {
1426                 self.s.word("break");
1427                 self.s.space();
1428                 if let Some(label) = destination.label {
1429                     self.print_ident(label.ident);
1430                     self.s.space();
1431                 }
1432                 if let Some(ref expr) = *opt_expr {
1433                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
1434                     self.s.space();
1435                 }
1436             }
1437             hir::ExprKind::Continue(destination) => {
1438                 self.s.word("continue");
1439                 self.s.space();
1440                 if let Some(label) = destination.label {
1441                     self.print_ident(label.ident);
1442                     self.s.space()
1443                 }
1444             }
1445             hir::ExprKind::Ret(ref result) => {
1446                 self.s.word("return");
1447                 if let Some(ref expr) = *result {
1448                     self.s.word(" ");
1449                     self.print_expr_maybe_paren(&expr, parser::PREC_JUMP);
1450                 }
1451             }
1452             hir::ExprKind::InlineAsm(ref a) => {
1453                 enum AsmArg<'a> {
1454                     Template(String),
1455                     Operand(&'a hir::InlineAsmOperand<'a>),
1456                     Options(ast::InlineAsmOptions),
1457                 }
1458
1459                 let mut args = vec![];
1460                 args.push(AsmArg::Template(ast::InlineAsmTemplatePiece::to_string(&a.template)));
1461                 args.extend(a.operands.iter().map(|o| AsmArg::Operand(o)));
1462                 if !a.options.is_empty() {
1463                     args.push(AsmArg::Options(a.options));
1464                 }
1465
1466                 self.word("asm!");
1467                 self.popen();
1468                 self.commasep(Consistent, &args, |s, arg| match arg {
1469                     AsmArg::Template(template) => s.print_string(&template, ast::StrStyle::Cooked),
1470                     AsmArg::Operand(op) => match op {
1471                         hir::InlineAsmOperand::In { reg, expr } => {
1472                             s.word("in");
1473                             s.popen();
1474                             s.word(format!("{}", reg));
1475                             s.pclose();
1476                             s.space();
1477                             s.print_expr(expr);
1478                         }
1479                         hir::InlineAsmOperand::Out { reg, late, expr } => {
1480                             s.word(if *late { "lateout" } else { "out" });
1481                             s.popen();
1482                             s.word(format!("{}", reg));
1483                             s.pclose();
1484                             s.space();
1485                             match expr {
1486                                 Some(expr) => s.print_expr(expr),
1487                                 None => s.word("_"),
1488                             }
1489                         }
1490                         hir::InlineAsmOperand::InOut { reg, late, expr } => {
1491                             s.word(if *late { "inlateout" } else { "inout" });
1492                             s.popen();
1493                             s.word(format!("{}", reg));
1494                             s.pclose();
1495                             s.space();
1496                             s.print_expr(expr);
1497                         }
1498                         hir::InlineAsmOperand::SplitInOut { reg, late, in_expr, out_expr } => {
1499                             s.word(if *late { "inlateout" } else { "inout" });
1500                             s.popen();
1501                             s.word(format!("{}", reg));
1502                             s.pclose();
1503                             s.space();
1504                             s.print_expr(in_expr);
1505                             s.space();
1506                             s.word_space("=>");
1507                             match out_expr {
1508                                 Some(out_expr) => s.print_expr(out_expr),
1509                                 None => s.word("_"),
1510                             }
1511                         }
1512                         hir::InlineAsmOperand::Const { expr } => {
1513                             s.word("const");
1514                             s.space();
1515                             s.print_expr(expr);
1516                         }
1517                         hir::InlineAsmOperand::Sym { expr } => {
1518                             s.word("sym");
1519                             s.space();
1520                             s.print_expr(expr);
1521                         }
1522                     },
1523                     AsmArg::Options(opts) => {
1524                         s.word("options");
1525                         s.popen();
1526                         let mut options = vec![];
1527                         if opts.contains(ast::InlineAsmOptions::PURE) {
1528                             options.push("pure");
1529                         }
1530                         if opts.contains(ast::InlineAsmOptions::NOMEM) {
1531                             options.push("nomem");
1532                         }
1533                         if opts.contains(ast::InlineAsmOptions::READONLY) {
1534                             options.push("readonly");
1535                         }
1536                         if opts.contains(ast::InlineAsmOptions::PRESERVES_FLAGS) {
1537                             options.push("preserves_flags");
1538                         }
1539                         if opts.contains(ast::InlineAsmOptions::NORETURN) {
1540                             options.push("noreturn");
1541                         }
1542                         if opts.contains(ast::InlineAsmOptions::NOSTACK) {
1543                             options.push("nostack");
1544                         }
1545                         if opts.contains(ast::InlineAsmOptions::ATT_SYNTAX) {
1546                             options.push("att_syntax");
1547                         }
1548                         s.commasep(Inconsistent, &options, |s, &opt| {
1549                             s.word(opt);
1550                         });
1551                         s.pclose();
1552                     }
1553                 });
1554                 self.pclose();
1555             }
1556             hir::ExprKind::LlvmInlineAsm(ref a) => {
1557                 let i = &a.inner;
1558                 self.s.word("llvm_asm!");
1559                 self.popen();
1560                 self.print_symbol(i.asm, i.asm_str_style);
1561                 self.word_space(":");
1562
1563                 let mut out_idx = 0;
1564                 self.commasep(Inconsistent, &i.outputs, |s, out| {
1565                     let constraint = out.constraint.as_str();
1566                     let mut ch = constraint.chars();
1567                     match ch.next() {
1568                         Some('=') if out.is_rw => {
1569                             s.print_string(&format!("+{}", ch.as_str()), ast::StrStyle::Cooked)
1570                         }
1571                         _ => s.print_string(&constraint, ast::StrStyle::Cooked),
1572                     }
1573                     s.popen();
1574                     s.print_expr(&a.outputs_exprs[out_idx]);
1575                     s.pclose();
1576                     out_idx += 1;
1577                 });
1578                 self.s.space();
1579                 self.word_space(":");
1580
1581                 let mut in_idx = 0;
1582                 self.commasep(Inconsistent, &i.inputs, |s, &co| {
1583                     s.print_symbol(co, ast::StrStyle::Cooked);
1584                     s.popen();
1585                     s.print_expr(&a.inputs_exprs[in_idx]);
1586                     s.pclose();
1587                     in_idx += 1;
1588                 });
1589                 self.s.space();
1590                 self.word_space(":");
1591
1592                 self.commasep(Inconsistent, &i.clobbers, |s, &co| {
1593                     s.print_symbol(co, ast::StrStyle::Cooked);
1594                 });
1595
1596                 let mut options = vec![];
1597                 if i.volatile {
1598                     options.push("volatile");
1599                 }
1600                 if i.alignstack {
1601                     options.push("alignstack");
1602                 }
1603                 if i.dialect == ast::LlvmAsmDialect::Intel {
1604                     options.push("intel");
1605                 }
1606
1607                 if !options.is_empty() {
1608                     self.s.space();
1609                     self.word_space(":");
1610                     self.commasep(Inconsistent, &options, |s, &co| {
1611                         s.print_string(co, ast::StrStyle::Cooked);
1612                     });
1613                 }
1614
1615                 self.pclose();
1616             }
1617             hir::ExprKind::Yield(ref expr, _) => {
1618                 self.word_space("yield");
1619                 self.print_expr_maybe_paren(&expr, parser::PREC_JUMP);
1620             }
1621             hir::ExprKind::Err => {
1622                 self.popen();
1623                 self.s.word("/*ERROR*/");
1624                 self.pclose();
1625             }
1626         }
1627         self.ann.post(self, AnnNode::Expr(expr));
1628         self.end()
1629     }
1630
1631     pub fn print_local_decl(&mut self, loc: &hir::Local<'_>) {
1632         self.print_pat(&loc.pat);
1633         if let Some(ref ty) = loc.ty {
1634             self.word_space(":");
1635             self.print_type(&ty);
1636         }
1637     }
1638
1639     pub fn print_usize(&mut self, i: usize) {
1640         self.s.word(i.to_string())
1641     }
1642
1643     pub fn print_name(&mut self, name: Symbol) {
1644         self.print_ident(Ident::with_dummy_span(name))
1645     }
1646
1647     pub fn print_for_decl(&mut self, loc: &hir::Local<'_>, coll: &hir::Expr<'_>) {
1648         self.print_local_decl(loc);
1649         self.s.space();
1650         self.word_space("in");
1651         self.print_expr(coll)
1652     }
1653
1654     pub fn print_path(&mut self, path: &hir::Path<'_>, colons_before_params: bool) {
1655         self.maybe_print_comment(path.span.lo());
1656
1657         for (i, segment) in path.segments.iter().enumerate() {
1658             if i > 0 {
1659                 self.s.word("::")
1660             }
1661             if segment.ident.name != kw::PathRoot {
1662                 self.print_ident(segment.ident);
1663                 self.print_generic_args(
1664                     segment.generic_args(),
1665                     segment.infer_args,
1666                     colons_before_params,
1667                 );
1668             }
1669         }
1670     }
1671
1672     pub fn print_path_segment(&mut self, segment: &hir::PathSegment<'_>) {
1673         if segment.ident.name != kw::PathRoot {
1674             self.print_ident(segment.ident);
1675             self.print_generic_args(segment.generic_args(), segment.infer_args, false);
1676         }
1677     }
1678
1679     pub fn print_qpath(&mut self, qpath: &hir::QPath<'_>, colons_before_params: bool) {
1680         match *qpath {
1681             hir::QPath::Resolved(None, ref path) => self.print_path(path, colons_before_params),
1682             hir::QPath::Resolved(Some(ref qself), ref path) => {
1683                 self.s.word("<");
1684                 self.print_type(qself);
1685                 self.s.space();
1686                 self.word_space("as");
1687
1688                 for (i, segment) in path.segments[..path.segments.len() - 1].iter().enumerate() {
1689                     if i > 0 {
1690                         self.s.word("::")
1691                     }
1692                     if segment.ident.name != kw::PathRoot {
1693                         self.print_ident(segment.ident);
1694                         self.print_generic_args(
1695                             segment.generic_args(),
1696                             segment.infer_args,
1697                             colons_before_params,
1698                         );
1699                     }
1700                 }
1701
1702                 self.s.word(">");
1703                 self.s.word("::");
1704                 let item_segment = path.segments.last().unwrap();
1705                 self.print_ident(item_segment.ident);
1706                 self.print_generic_args(
1707                     item_segment.generic_args(),
1708                     item_segment.infer_args,
1709                     colons_before_params,
1710                 )
1711             }
1712             hir::QPath::TypeRelative(ref qself, ref item_segment) => {
1713                 // If we've got a compound-qualified-path, let's push an additional pair of angle
1714                 // brackets, so that we pretty-print `<<A::B>::C>` as `<A::B>::C`, instead of just
1715                 // `A::B::C` (since the latter could be ambiguous to the user)
1716                 if let hir::TyKind::Path(hir::QPath::Resolved(None, _)) = &qself.kind {
1717                     self.print_type(qself);
1718                 } else {
1719                     self.s.word("<");
1720                     self.print_type(qself);
1721                     self.s.word(">");
1722                 }
1723
1724                 self.s.word("::");
1725                 self.print_ident(item_segment.ident);
1726                 self.print_generic_args(
1727                     item_segment.generic_args(),
1728                     item_segment.infer_args,
1729                     colons_before_params,
1730                 )
1731             }
1732             hir::QPath::LangItem(lang_item, span) => {
1733                 self.s.word("#[lang = \"");
1734                 self.print_ident(Ident::new(lang_item.name(), span));
1735                 self.s.word("\"]");
1736             }
1737         }
1738     }
1739
1740     fn print_generic_args(
1741         &mut self,
1742         generic_args: &hir::GenericArgs<'_>,
1743         infer_args: bool,
1744         colons_before_params: bool,
1745     ) {
1746         if generic_args.parenthesized {
1747             self.s.word("(");
1748             self.commasep(Inconsistent, generic_args.inputs(), |s, ty| s.print_type(&ty));
1749             self.s.word(")");
1750
1751             self.space_if_not_bol();
1752             self.word_space("->");
1753             self.print_type(generic_args.bindings[0].ty());
1754         } else {
1755             let start = if colons_before_params { "::<" } else { "<" };
1756             let empty = Cell::new(true);
1757             let start_or_comma = |this: &mut Self| {
1758                 if empty.get() {
1759                     empty.set(false);
1760                     this.s.word(start)
1761                 } else {
1762                     this.word_space(",")
1763                 }
1764             };
1765
1766             let mut nonelided_generic_args: bool = false;
1767             let elide_lifetimes = generic_args.args.iter().all(|arg| match arg {
1768                 GenericArg::Lifetime(lt) => lt.is_elided(),
1769                 _ => {
1770                     nonelided_generic_args = true;
1771                     true
1772                 }
1773             });
1774
1775             if nonelided_generic_args {
1776                 start_or_comma(self);
1777                 self.commasep(
1778                     Inconsistent,
1779                     &generic_args.args,
1780                     |s, generic_arg| match generic_arg {
1781                         GenericArg::Lifetime(lt) if !elide_lifetimes => s.print_lifetime(lt),
1782                         GenericArg::Lifetime(_) => {}
1783                         GenericArg::Type(ty) => s.print_type(ty),
1784                         GenericArg::Const(ct) => s.print_anon_const(&ct.value),
1785                     },
1786                 );
1787             }
1788
1789             // FIXME(eddyb): this would leak into error messages (e.g.,
1790             // "non-exhaustive patterns: `Some::<..>(_)` not covered").
1791             if infer_args && false {
1792                 start_or_comma(self);
1793                 self.s.word("..");
1794             }
1795
1796             for binding in generic_args.bindings.iter() {
1797                 start_or_comma(self);
1798                 self.print_ident(binding.ident);
1799                 self.s.space();
1800                 match generic_args.bindings[0].kind {
1801                     hir::TypeBindingKind::Equality { ref ty } => {
1802                         self.word_space("=");
1803                         self.print_type(ty);
1804                     }
1805                     hir::TypeBindingKind::Constraint { bounds } => {
1806                         self.print_bounds(":", bounds);
1807                     }
1808                 }
1809             }
1810
1811             if !empty.get() {
1812                 self.s.word(">")
1813             }
1814         }
1815     }
1816
1817     pub fn print_pat(&mut self, pat: &hir::Pat<'_>) {
1818         self.maybe_print_comment(pat.span.lo());
1819         self.ann.pre(self, AnnNode::Pat(pat));
1820         // Pat isn't normalized, but the beauty of it
1821         // is that it doesn't matter
1822         match pat.kind {
1823             PatKind::Wild => self.s.word("_"),
1824             PatKind::Binding(binding_mode, _, ident, ref sub) => {
1825                 match binding_mode {
1826                     hir::BindingAnnotation::Ref => {
1827                         self.word_nbsp("ref");
1828                         self.print_mutability(hir::Mutability::Not, false);
1829                     }
1830                     hir::BindingAnnotation::RefMut => {
1831                         self.word_nbsp("ref");
1832                         self.print_mutability(hir::Mutability::Mut, false);
1833                     }
1834                     hir::BindingAnnotation::Unannotated => {}
1835                     hir::BindingAnnotation::Mutable => {
1836                         self.word_nbsp("mut");
1837                     }
1838                 }
1839                 self.print_ident(ident);
1840                 if let Some(ref p) = *sub {
1841                     self.s.word("@");
1842                     self.print_pat(&p);
1843                 }
1844             }
1845             PatKind::TupleStruct(ref qpath, ref elts, ddpos) => {
1846                 self.print_qpath(qpath, true);
1847                 self.popen();
1848                 if let Some(ddpos) = ddpos {
1849                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p));
1850                     if ddpos != 0 {
1851                         self.word_space(",");
1852                     }
1853                     self.s.word("..");
1854                     if ddpos != elts.len() {
1855                         self.s.word(",");
1856                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p));
1857                     }
1858                 } else {
1859                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p));
1860                 }
1861                 self.pclose();
1862             }
1863             PatKind::Path(ref qpath) => {
1864                 self.print_qpath(qpath, true);
1865             }
1866             PatKind::Struct(ref qpath, ref fields, etc) => {
1867                 self.print_qpath(qpath, true);
1868                 self.nbsp();
1869                 self.word_space("{");
1870                 self.commasep_cmnt(
1871                     Consistent,
1872                     &fields[..],
1873                     |s, f| {
1874                         s.cbox(INDENT_UNIT);
1875                         if !f.is_shorthand {
1876                             s.print_ident(f.ident);
1877                             s.word_nbsp(":");
1878                         }
1879                         s.print_pat(&f.pat);
1880                         s.end()
1881                     },
1882                     |f| f.pat.span,
1883                 );
1884                 if etc {
1885                     if !fields.is_empty() {
1886                         self.word_space(",");
1887                     }
1888                     self.s.word("..");
1889                 }
1890                 self.s.space();
1891                 self.s.word("}");
1892             }
1893             PatKind::Or(ref pats) => {
1894                 self.strsep("|", true, Inconsistent, &pats[..], |s, p| s.print_pat(&p));
1895             }
1896             PatKind::Tuple(ref elts, ddpos) => {
1897                 self.popen();
1898                 if let Some(ddpos) = ddpos {
1899                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p));
1900                     if ddpos != 0 {
1901                         self.word_space(",");
1902                     }
1903                     self.s.word("..");
1904                     if ddpos != elts.len() {
1905                         self.s.word(",");
1906                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p));
1907                     }
1908                 } else {
1909                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p));
1910                     if elts.len() == 1 {
1911                         self.s.word(",");
1912                     }
1913                 }
1914                 self.pclose();
1915             }
1916             PatKind::Box(ref inner) => {
1917                 let is_range_inner = match inner.kind {
1918                     PatKind::Range(..) => true,
1919                     _ => false,
1920                 };
1921                 self.s.word("box ");
1922                 if is_range_inner {
1923                     self.popen();
1924                 }
1925                 self.print_pat(&inner);
1926                 if is_range_inner {
1927                     self.pclose();
1928                 }
1929             }
1930             PatKind::Ref(ref inner, mutbl) => {
1931                 let is_range_inner = match inner.kind {
1932                     PatKind::Range(..) => true,
1933                     _ => false,
1934                 };
1935                 self.s.word("&");
1936                 self.s.word(mutbl.prefix_str());
1937                 if is_range_inner {
1938                     self.popen();
1939                 }
1940                 self.print_pat(&inner);
1941                 if is_range_inner {
1942                     self.pclose();
1943                 }
1944             }
1945             PatKind::Lit(ref e) => self.print_expr(&e),
1946             PatKind::Range(ref begin, ref end, ref end_kind) => {
1947                 if let Some(expr) = begin {
1948                     self.print_expr(expr);
1949                     self.s.space();
1950                 }
1951                 match *end_kind {
1952                     RangeEnd::Included => self.s.word("..."),
1953                     RangeEnd::Excluded => self.s.word(".."),
1954                 }
1955                 if let Some(expr) = end {
1956                     self.print_expr(expr);
1957                 }
1958             }
1959             PatKind::Slice(ref before, ref slice, ref after) => {
1960                 self.s.word("[");
1961                 self.commasep(Inconsistent, &before[..], |s, p| s.print_pat(&p));
1962                 if let Some(ref p) = *slice {
1963                     if !before.is_empty() {
1964                         self.word_space(",");
1965                     }
1966                     if let PatKind::Wild = p.kind {
1967                         // Print nothing.
1968                     } else {
1969                         self.print_pat(&p);
1970                     }
1971                     self.s.word("..");
1972                     if !after.is_empty() {
1973                         self.word_space(",");
1974                     }
1975                 }
1976                 self.commasep(Inconsistent, &after[..], |s, p| s.print_pat(&p));
1977                 self.s.word("]");
1978             }
1979         }
1980         self.ann.post(self, AnnNode::Pat(pat))
1981     }
1982
1983     pub fn print_param(&mut self, arg: &hir::Param<'_>) {
1984         self.print_outer_attributes(&arg.attrs);
1985         self.print_pat(&arg.pat);
1986     }
1987
1988     pub fn print_arm(&mut self, arm: &hir::Arm<'_>) {
1989         // I have no idea why this check is necessary, but here it
1990         // is :(
1991         if arm.attrs.is_empty() {
1992             self.s.space();
1993         }
1994         self.cbox(INDENT_UNIT);
1995         self.ann.pre(self, AnnNode::Arm(arm));
1996         self.ibox(0);
1997         self.print_outer_attributes(&arm.attrs);
1998         self.print_pat(&arm.pat);
1999         self.s.space();
2000         if let Some(ref g) = arm.guard {
2001             match g {
2002                 hir::Guard::If(e) => {
2003                     self.word_space("if");
2004                     self.print_expr(&e);
2005                     self.s.space();
2006                 }
2007             }
2008         }
2009         self.word_space("=>");
2010
2011         match arm.body.kind {
2012             hir::ExprKind::Block(ref blk, opt_label) => {
2013                 if let Some(label) = opt_label {
2014                     self.print_ident(label.ident);
2015                     self.word_space(":");
2016                 }
2017                 // the block will close the pattern's ibox
2018                 self.print_block_unclosed(&blk);
2019
2020                 // If it is a user-provided unsafe block, print a comma after it
2021                 if let hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::UserProvided) = blk.rules
2022                 {
2023                     self.s.word(",");
2024                 }
2025             }
2026             _ => {
2027                 self.end(); // close the ibox for the pattern
2028                 self.print_expr(&arm.body);
2029                 self.s.word(",");
2030             }
2031         }
2032         self.ann.post(self, AnnNode::Arm(arm));
2033         self.end() // close enclosing cbox
2034     }
2035
2036     pub fn print_fn(
2037         &mut self,
2038         decl: &hir::FnDecl<'_>,
2039         header: hir::FnHeader,
2040         name: Option<Symbol>,
2041         generics: &hir::Generics<'_>,
2042         vis: &hir::Visibility<'_>,
2043         arg_names: &[Ident],
2044         body_id: Option<hir::BodyId>,
2045     ) {
2046         self.print_fn_header_info(header, vis);
2047
2048         if let Some(name) = name {
2049             self.nbsp();
2050             self.print_name(name);
2051         }
2052         self.print_generic_params(&generics.params);
2053
2054         self.popen();
2055         let mut i = 0;
2056         // Make sure we aren't supplied *both* `arg_names` and `body_id`.
2057         assert!(arg_names.is_empty() || body_id.is_none());
2058         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
2059             s.ibox(INDENT_UNIT);
2060             if let Some(arg_name) = arg_names.get(i) {
2061                 s.s.word(arg_name.to_string());
2062                 s.s.word(":");
2063                 s.s.space();
2064             } else if let Some(body_id) = body_id {
2065                 s.ann.nested(s, Nested::BodyParamPat(body_id, i));
2066                 s.s.word(":");
2067                 s.s.space();
2068             }
2069             i += 1;
2070             s.print_type(ty);
2071             s.end()
2072         });
2073         if decl.c_variadic {
2074             self.s.word(", ...");
2075         }
2076         self.pclose();
2077
2078         self.print_fn_output(decl);
2079         self.print_where_clause(&generics.where_clause)
2080     }
2081
2082     fn print_closure_params(&mut self, decl: &hir::FnDecl<'_>, body_id: hir::BodyId) {
2083         self.s.word("|");
2084         let mut i = 0;
2085         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
2086             s.ibox(INDENT_UNIT);
2087
2088             s.ann.nested(s, Nested::BodyParamPat(body_id, i));
2089             i += 1;
2090
2091             if let hir::TyKind::Infer = ty.kind {
2092                 // Print nothing.
2093             } else {
2094                 s.s.word(":");
2095                 s.s.space();
2096                 s.print_type(ty);
2097             }
2098             s.end();
2099         });
2100         self.s.word("|");
2101
2102         if let hir::FnRetTy::DefaultReturn(..) = decl.output {
2103             return;
2104         }
2105
2106         self.space_if_not_bol();
2107         self.word_space("->");
2108         match decl.output {
2109             hir::FnRetTy::Return(ref ty) => {
2110                 self.print_type(&ty);
2111                 self.maybe_print_comment(ty.span.lo())
2112             }
2113             hir::FnRetTy::DefaultReturn(..) => unreachable!(),
2114         }
2115     }
2116
2117     pub fn print_capture_clause(&mut self, capture_clause: hir::CaptureBy) {
2118         match capture_clause {
2119             hir::CaptureBy::Value => self.word_space("move"),
2120             hir::CaptureBy::Ref => {}
2121         }
2122     }
2123
2124     pub fn print_bounds<'b>(
2125         &mut self,
2126         prefix: &'static str,
2127         bounds: impl IntoIterator<Item = &'b hir::GenericBound<'b>>,
2128     ) {
2129         let mut first = true;
2130         for bound in bounds {
2131             if first {
2132                 self.s.word(prefix);
2133             }
2134             if !(first && prefix.is_empty()) {
2135                 self.nbsp();
2136             }
2137             if first {
2138                 first = false;
2139             } else {
2140                 self.word_space("+");
2141             }
2142
2143             match bound {
2144                 GenericBound::Trait(tref, modifier) => {
2145                     if modifier == &TraitBoundModifier::Maybe {
2146                         self.s.word("?");
2147                     }
2148                     self.print_poly_trait_ref(tref);
2149                 }
2150                 GenericBound::LangItemTrait(lang_item, span, ..) => {
2151                     self.s.word("#[lang = \"");
2152                     self.print_ident(Ident::new(lang_item.name(), *span));
2153                     self.s.word("\"]");
2154                 }
2155                 GenericBound::Outlives(lt) => {
2156                     self.print_lifetime(lt);
2157                 }
2158             }
2159         }
2160     }
2161
2162     pub fn print_generic_params(&mut self, generic_params: &[GenericParam<'_>]) {
2163         if !generic_params.is_empty() {
2164             self.s.word("<");
2165
2166             self.commasep(Inconsistent, generic_params, |s, param| s.print_generic_param(param));
2167
2168             self.s.word(">");
2169         }
2170     }
2171
2172     pub fn print_generic_param(&mut self, param: &GenericParam<'_>) {
2173         if let GenericParamKind::Const { .. } = param.kind {
2174             self.word_space("const");
2175         }
2176
2177         self.print_ident(param.name.ident());
2178
2179         match param.kind {
2180             GenericParamKind::Lifetime { .. } => {
2181                 let mut sep = ":";
2182                 for bound in param.bounds {
2183                     match bound {
2184                         GenericBound::Outlives(ref lt) => {
2185                             self.s.word(sep);
2186                             self.print_lifetime(lt);
2187                             sep = "+";
2188                         }
2189                         _ => panic!(),
2190                     }
2191                 }
2192             }
2193             GenericParamKind::Type { ref default, .. } => {
2194                 self.print_bounds(":", param.bounds);
2195                 if let Some(default) = default {
2196                     self.s.space();
2197                     self.word_space("=");
2198                     self.print_type(&default)
2199                 }
2200             }
2201             GenericParamKind::Const { ref ty } => {
2202                 self.word_space(":");
2203                 self.print_type(ty)
2204             }
2205         }
2206     }
2207
2208     pub fn print_lifetime(&mut self, lifetime: &hir::Lifetime) {
2209         self.print_ident(lifetime.name.ident())
2210     }
2211
2212     pub fn print_where_clause(&mut self, where_clause: &hir::WhereClause<'_>) {
2213         if where_clause.predicates.is_empty() {
2214             return;
2215         }
2216
2217         self.s.space();
2218         self.word_space("where");
2219
2220         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2221             if i != 0 {
2222                 self.word_space(",");
2223             }
2224
2225             match predicate {
2226                 &hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
2227                     ref bound_generic_params,
2228                     ref bounded_ty,
2229                     bounds,
2230                     ..
2231                 }) => {
2232                     self.print_formal_generic_params(bound_generic_params);
2233                     self.print_type(&bounded_ty);
2234                     self.print_bounds(":", bounds);
2235                 }
2236                 &hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
2237                     ref lifetime,
2238                     ref bounds,
2239                     ..
2240                 }) => {
2241                     self.print_lifetime(lifetime);
2242                     self.s.word(":");
2243
2244                     for (i, bound) in bounds.iter().enumerate() {
2245                         match bound {
2246                             GenericBound::Outlives(lt) => {
2247                                 self.print_lifetime(lt);
2248                             }
2249                             _ => panic!(),
2250                         }
2251
2252                         if i != 0 {
2253                             self.s.word(":");
2254                         }
2255                     }
2256                 }
2257                 &hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
2258                     ref lhs_ty,
2259                     ref rhs_ty,
2260                     ..
2261                 }) => {
2262                     self.print_type(lhs_ty);
2263                     self.s.space();
2264                     self.word_space("=");
2265                     self.print_type(rhs_ty);
2266                 }
2267             }
2268         }
2269     }
2270
2271     pub fn print_mutability(&mut self, mutbl: hir::Mutability, print_const: bool) {
2272         match mutbl {
2273             hir::Mutability::Mut => self.word_nbsp("mut"),
2274             hir::Mutability::Not => {
2275                 if print_const {
2276                     self.word_nbsp("const")
2277                 }
2278             }
2279         }
2280     }
2281
2282     pub fn print_mt(&mut self, mt: &hir::MutTy<'_>, print_const: bool) {
2283         self.print_mutability(mt.mutbl, print_const);
2284         self.print_type(&mt.ty)
2285     }
2286
2287     pub fn print_fn_output(&mut self, decl: &hir::FnDecl<'_>) {
2288         if let hir::FnRetTy::DefaultReturn(..) = decl.output {
2289             return;
2290         }
2291
2292         self.space_if_not_bol();
2293         self.ibox(INDENT_UNIT);
2294         self.word_space("->");
2295         match decl.output {
2296             hir::FnRetTy::DefaultReturn(..) => unreachable!(),
2297             hir::FnRetTy::Return(ref ty) => self.print_type(&ty),
2298         }
2299         self.end();
2300
2301         if let hir::FnRetTy::Return(ref output) = decl.output {
2302             self.maybe_print_comment(output.span.lo())
2303         }
2304     }
2305
2306     pub fn print_ty_fn(
2307         &mut self,
2308         abi: Abi,
2309         unsafety: hir::Unsafety,
2310         decl: &hir::FnDecl<'_>,
2311         name: Option<Symbol>,
2312         generic_params: &[hir::GenericParam<'_>],
2313         arg_names: &[Ident],
2314     ) {
2315         self.ibox(INDENT_UNIT);
2316         if !generic_params.is_empty() {
2317             self.s.word("for");
2318             self.print_generic_params(generic_params);
2319         }
2320         let generics = hir::Generics {
2321             params: &[],
2322             where_clause: hir::WhereClause { predicates: &[], span: rustc_span::DUMMY_SP },
2323             span: rustc_span::DUMMY_SP,
2324         };
2325         self.print_fn(
2326             decl,
2327             hir::FnHeader {
2328                 unsafety,
2329                 abi,
2330                 constness: hir::Constness::NotConst,
2331                 asyncness: hir::IsAsync::NotAsync,
2332             },
2333             name,
2334             &generics,
2335             &Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited },
2336             arg_names,
2337             None,
2338         );
2339         self.end();
2340     }
2341
2342     pub fn maybe_print_trailing_comment(
2343         &mut self,
2344         span: rustc_span::Span,
2345         next_pos: Option<BytePos>,
2346     ) {
2347         if let Some(cmnts) = self.comments() {
2348             if let Some(cmnt) = cmnts.trailing_comment(span, next_pos) {
2349                 self.print_comment(&cmnt);
2350             }
2351         }
2352     }
2353
2354     pub fn print_remaining_comments(&mut self) {
2355         // If there aren't any remaining comments, then we need to manually
2356         // make sure there is a line break at the end.
2357         if self.next_comment().is_none() {
2358             self.s.hardbreak();
2359         }
2360         while let Some(ref cmnt) = self.next_comment() {
2361             self.print_comment(cmnt)
2362         }
2363     }
2364
2365     pub fn print_opt_abi_and_extern_if_nondefault(&mut self, opt_abi: Option<Abi>) {
2366         match opt_abi {
2367             Some(Abi::Rust) => {}
2368             Some(abi) => {
2369                 self.word_nbsp("extern");
2370                 self.word_nbsp(abi.to_string())
2371             }
2372             None => {}
2373         }
2374     }
2375
2376     pub fn print_extern_opt_abi(&mut self, opt_abi: Option<Abi>) {
2377         if let Some(abi) = opt_abi {
2378             self.word_nbsp("extern");
2379             self.word_nbsp(abi.to_string())
2380         }
2381     }
2382
2383     pub fn print_fn_header_info(&mut self, header: hir::FnHeader, vis: &hir::Visibility<'_>) {
2384         self.s.word(visibility_qualified(vis, ""));
2385
2386         match header.constness {
2387             hir::Constness::NotConst => {}
2388             hir::Constness::Const => self.word_nbsp("const"),
2389         }
2390
2391         match header.asyncness {
2392             hir::IsAsync::NotAsync => {}
2393             hir::IsAsync::Async => self.word_nbsp("async"),
2394         }
2395
2396         self.print_unsafety(header.unsafety);
2397
2398         if header.abi != Abi::Rust {
2399             self.word_nbsp("extern");
2400             self.word_nbsp(header.abi.to_string());
2401         }
2402
2403         self.s.word("fn")
2404     }
2405
2406     pub fn print_unsafety(&mut self, s: hir::Unsafety) {
2407         match s {
2408             hir::Unsafety::Normal => {}
2409             hir::Unsafety::Unsafe => self.word_nbsp("unsafe"),
2410         }
2411     }
2412
2413     pub fn print_is_auto(&mut self, s: hir::IsAuto) {
2414         match s {
2415             hir::IsAuto::Yes => self.word_nbsp("auto"),
2416             hir::IsAuto::No => {}
2417         }
2418     }
2419 }
2420
2421 /// Does this expression require a semicolon to be treated
2422 /// as a statement? The negation of this: 'can this expression
2423 /// be used as a statement without a semicolon' -- is used
2424 /// as an early-bail-out in the parser so that, for instance,
2425 ///     if true {...} else {...}
2426 ///      |x| 5
2427 /// isn't parsed as (if true {...} else {...} | x) | 5
2428 //
2429 // Duplicated from `parse::classify`, but adapted for the HIR.
2430 fn expr_requires_semi_to_be_stmt(e: &hir::Expr<'_>) -> bool {
2431     match e.kind {
2432         hir::ExprKind::Match(..) | hir::ExprKind::Block(..) | hir::ExprKind::Loop(..) => false,
2433         _ => true,
2434     }
2435 }
2436
2437 /// This statement requires a semicolon after it.
2438 /// note that in one case (stmt_semi), we've already
2439 /// seen the semicolon, and thus don't need another.
2440 fn stmt_ends_with_semi(stmt: &hir::StmtKind<'_>) -> bool {
2441     match *stmt {
2442         hir::StmtKind::Local(_) => true,
2443         hir::StmtKind::Item(_) => false,
2444         hir::StmtKind::Expr(ref e) => expr_requires_semi_to_be_stmt(&e),
2445         hir::StmtKind::Semi(..) => false,
2446     }
2447 }
2448
2449 fn bin_op_to_assoc_op(op: hir::BinOpKind) -> AssocOp {
2450     use crate::hir::BinOpKind::*;
2451     match op {
2452         Add => AssocOp::Add,
2453         Sub => AssocOp::Subtract,
2454         Mul => AssocOp::Multiply,
2455         Div => AssocOp::Divide,
2456         Rem => AssocOp::Modulus,
2457
2458         And => AssocOp::LAnd,
2459         Or => AssocOp::LOr,
2460
2461         BitXor => AssocOp::BitXor,
2462         BitAnd => AssocOp::BitAnd,
2463         BitOr => AssocOp::BitOr,
2464         Shl => AssocOp::ShiftLeft,
2465         Shr => AssocOp::ShiftRight,
2466
2467         Eq => AssocOp::Equal,
2468         Lt => AssocOp::Less,
2469         Le => AssocOp::LessEqual,
2470         Ne => AssocOp::NotEqual,
2471         Ge => AssocOp::GreaterEqual,
2472         Gt => AssocOp::Greater,
2473     }
2474 }
2475
2476 /// Expressions that syntactically contain an "exterior" struct literal, i.e., not surrounded by any
2477 /// parens or other delimiters, e.g., `X { y: 1 }`, `X { y: 1 }.method()`, `foo == X { y: 1 }` and
2478 /// `X { y: 1 } == foo` all do, but `(X { y: 1 }) == foo` does not.
2479 fn contains_exterior_struct_lit(value: &hir::Expr<'_>) -> bool {
2480     match value.kind {
2481         hir::ExprKind::Struct(..) => true,
2482
2483         hir::ExprKind::Assign(ref lhs, ref rhs, _)
2484         | hir::ExprKind::AssignOp(_, ref lhs, ref rhs)
2485         | hir::ExprKind::Binary(_, ref lhs, ref rhs) => {
2486             // `X { y: 1 } + X { y: 2 }`
2487             contains_exterior_struct_lit(&lhs) || contains_exterior_struct_lit(&rhs)
2488         }
2489         hir::ExprKind::Unary(_, ref x)
2490         | hir::ExprKind::Cast(ref x, _)
2491         | hir::ExprKind::Type(ref x, _)
2492         | hir::ExprKind::Field(ref x, _)
2493         | hir::ExprKind::Index(ref x, _) => {
2494             // `&X { y: 1 }, X { y: 1 }.y`
2495             contains_exterior_struct_lit(&x)
2496         }
2497
2498         hir::ExprKind::MethodCall(.., ref exprs, _) => {
2499             // `X { y: 1 }.bar(...)`
2500             contains_exterior_struct_lit(&exprs[0])
2501         }
2502
2503         _ => false,
2504     }
2505 }