compiler/rustc_hir_pretty/src/lib.rs

   1 #![recursion_limit = "256"]
   2
   3 use rustc_ast as ast;
   4 use rustc_ast::util::parser::{self, AssocOp, Fixity};
   5 use rustc_ast_pretty::pp::Breaks::{Consistent, Inconsistent};
   6 use rustc_ast_pretty::pp::{self, Breaks};
   7 use rustc_ast_pretty::pprust::{Comments, PrintState};
   8 use rustc_hir as hir;
   9 use rustc_hir::{GenericArg, GenericParam, GenericParamKind, Node};
  10 use rustc_hir::{GenericBound, PatKind, RangeEnd, TraitBoundModifier};
  11 use rustc_span::source_map::{SourceMap, Spanned};
  12 use rustc_span::symbol::{kw, Ident, IdentPrinter, Symbol};
  13 use rustc_span::{self, BytePos, FileName};
  14 use rustc_target::spec::abi::Abi;
  15
  16 use std::borrow::Cow;
  17 use std::cell::Cell;
  18 use std::collections::BTreeMap;
  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     ForeignItem(hir::ForeignItemId),
  40     Body(hir::BodyId),
  41     BodyParamPat(hir::BodyId, usize),
  42 }
  43
  44 pub trait PpAnn {
  45     fn nested(&self, _state: &mut State<'_>, _nested: Nested) {}
  46     fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
  47     fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
  48 }
  49
  50 pub struct NoAnn;
  51 impl PpAnn for NoAnn {}
  52 pub const NO_ANN: &dyn PpAnn = &NoAnn;
  53
  54 impl PpAnn for hir::Crate<'_> {
  55     fn nested(&self, state: &mut State<'_>, nested: Nested) {
  56         match nested {
  57             Nested::Item(id) => state.print_item(self.item(id)),
  58             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
  59             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
  60             Nested::ForeignItem(id) => state.print_foreign_item(self.foreign_item(id)),
  61             Nested::Body(id) => state.print_expr(&self.body(id).value),
  62             Nested::BodyParamPat(id, i) => state.print_pat(&self.body(id).params[i].pat),
  63         }
  64     }
  65 }
  66
  67 /// Identical to the `PpAnn` implementation for `hir::Crate`,
  68 /// except it avoids creating a dependency on the whole crate.
  69 impl PpAnn for &dyn rustc_hir::intravisit::Map<'_> {
  70     fn nested(&self, state: &mut State<'_>, nested: Nested) {
  71         match nested {
  72             Nested::Item(id) => state.print_item(self.item(id)),
  73             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
  74             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
  75             Nested::ForeignItem(id) => state.print_foreign_item(self.foreign_item(id)),
  76             Nested::Body(id) => state.print_expr(&self.body(id).value),
  77             Nested::BodyParamPat(id, i) => state.print_pat(&self.body(id).params[i].pat),
  78         }
  79     }
  80 }
  81
  82 pub struct State<'a> {
  83     pub s: pp::Printer,
  84     comments: Option<Comments<'a>>,
  85     attrs: &'a BTreeMap<hir::HirId, &'a [ast::Attribute]>,
  86     ann: &'a (dyn PpAnn + 'a),
  87 }
  88
  89 impl<'a> State<'a> {
  90     pub fn print_node(&mut self, node: Node<'_>) {
  91         match node {
  92             Node::Param(a) => self.print_param(&a),
  93             Node::Item(a) => self.print_item(&a),
  94             Node::ForeignItem(a) => self.print_foreign_item(&a),
  95             Node::TraitItem(a) => self.print_trait_item(a),
  96             Node::ImplItem(a) => self.print_impl_item(a),
  97             Node::Variant(a) => self.print_variant(&a),
  98             Node::AnonConst(a) => self.print_anon_const(&a),
  99             Node::Expr(a) => self.print_expr(&a),
 100             Node::Stmt(a) => self.print_stmt(&a),
 101             Node::PathSegment(a) => self.print_path_segment(&a),
 102             Node::Ty(a) => self.print_type(&a),
 103             Node::TraitRef(a) => self.print_trait_ref(&a),
 104             Node::Binding(a) | Node::Pat(a) => self.print_pat(&a),
 105             Node::Arm(a) => self.print_arm(&a),
 106             Node::Infer(_) => self.s.word("_"),
 107             Node::Block(a) => {
 108                 // Containing cbox, will be closed by print-block at `}`.
 109                 self.cbox(INDENT_UNIT);
 110                 // Head-ibox, will be closed by print-block after `{`.
 111                 self.ibox(0);
 112                 self.print_block(&a)
 113             }
 114             Node::Lifetime(a) => self.print_lifetime(&a),
 115             Node::Visibility(a) => self.print_visibility(&a),
 116             Node::GenericParam(_) => panic!("cannot print Node::GenericParam"),
 117             Node::Field(_) => panic!("cannot print Node::Field"),
 118             // These cases do not carry enough information in the
 119             // `hir_map` to reconstruct their full structure for pretty
 120             // printing.
 121             Node::Ctor(..) => panic!("cannot print isolated Ctor"),
 122             Node::Local(a) => self.print_local_decl(&a),
 123             Node::MacroDef(_) => panic!("cannot print MacroDef"),
 124             Node::Crate(..) => panic!("cannot print Crate"),
 125         }
 126     }
 127 }
 128
 129 impl std::ops::Deref for State<'_> {
 130     type Target = pp::Printer;
 131     fn deref(&self) -> &Self::Target {
 132         &self.s
 133     }
 134 }
 135
 136 impl std::ops::DerefMut for State<'_> {
 137     fn deref_mut(&mut self) -> &mut Self::Target {
 138         &mut self.s
 139     }
 140 }
 141
 142 impl<'a> PrintState<'a> for State<'a> {
 143     fn comments(&mut self) -> &mut Option<Comments<'a>> {
 144         &mut self.comments
 145     }
 146
 147     fn print_ident(&mut self, ident: Ident) {
 148         self.s.word(IdentPrinter::for_ast_ident(ident, ident.is_raw_guess()).to_string());
 149         self.ann.post(self, AnnNode::Name(&ident.name))
 150     }
 151
 152     fn print_generic_args(&mut self, _: &ast::GenericArgs, _colons_before_params: bool) {
 153         panic!("AST generic args printed by HIR pretty-printer");
 154     }
 155 }
 156
 157 pub const INDENT_UNIT: usize = 4;
 158
 159 /// Requires you to pass an input filename and reader so that
 160 /// it can scan the input text for comments to copy forward.
 161 pub fn print_crate<'a>(
 162     sm: &'a SourceMap,
 163     krate: &hir::Crate<'_>,
 164     filename: FileName,
 165     input: String,
 166     ann: &'a dyn PpAnn,
 167 ) -> String {
 168     let mut s = State::new_from_input(sm, filename, input, &krate.attrs, ann);
 169
 170     // When printing the AST, we sometimes need to inject `#[no_std]` here.
 171     // Since you can't compile the HIR, it's not necessary.
 172
 173     s.print_mod(&krate.item, s.attrs(hir::CRATE_HIR_ID));
 174     s.print_remaining_comments();
 175     s.s.eof()
 176 }
 177
 178 impl<'a> State<'a> {
 179     pub fn new_from_input(
 180         sm: &'a SourceMap,
 181         filename: FileName,
 182         input: String,
 183         attrs: &'a BTreeMap<hir::HirId, &[ast::Attribute]>,
 184         ann: &'a dyn PpAnn,
 185     ) -> State<'a> {
 186         State {
 187             s: pp::mk_printer(),
 188             comments: Some(Comments::new(sm, filename, input)),
 189             attrs,
 190             ann,
 191         }
 192     }
 193
 194     fn attrs(&self, id: hir::HirId) -> &'a [ast::Attribute] {
 195         self.attrs.get(&id).map_or(&[], |la| *la)
 196     }
 197 }
 198
 199 pub fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
 200 where
 201     F: FnOnce(&mut State<'_>),
 202 {
 203     let mut printer =
 204         State { s: pp::mk_printer(), comments: None, attrs: &BTreeMap::default(), ann };
 205     f(&mut printer);
 206     printer.s.eof()
 207 }
 208
 209 pub fn visibility_qualified<S: Into<Cow<'static, str>>>(vis: &hir::Visibility<'_>, w: S) -> String {
 210     to_string(NO_ANN, |s| {
 211         s.print_visibility(vis);
 212         s.s.word(w)
 213     })
 214 }
 215
 216 pub fn generic_params_to_string(generic_params: &[GenericParam<'_>]) -> String {
 217     to_string(NO_ANN, |s| s.print_generic_params(generic_params))
 218 }
 219
 220 pub fn bounds_to_string<'b>(bounds: impl IntoIterator<Item = &'b hir::GenericBound<'b>>) -> String {
 221     to_string(NO_ANN, |s| s.print_bounds("", bounds))
 222 }
 223
 224 pub fn ty_to_string(ty: &hir::Ty<'_>) -> String {
 225     to_string(NO_ANN, |s| s.print_type(ty))
 226 }
 227
 228 pub fn path_segment_to_string(segment: &hir::PathSegment<'_>) -> String {
 229     to_string(NO_ANN, |s| s.print_path_segment(segment))
 230 }
 231
 232 pub fn path_to_string(segment: &hir::Path<'_>) -> String {
 233     to_string(NO_ANN, |s| s.print_path(segment, false))
 234 }
 235
 236 pub fn fn_to_string(
 237     decl: &hir::FnDecl<'_>,
 238     header: hir::FnHeader,
 239     name: Option<Symbol>,
 240     generics: &hir::Generics<'_>,
 241     vis: &hir::Visibility<'_>,
 242     arg_names: &[Ident],
 243     body_id: Option<hir::BodyId>,
 244 ) -> String {
 245     to_string(NO_ANN, |s| s.print_fn(decl, header, name, generics, vis, arg_names, body_id))
 246 }
 247
 248 pub fn enum_def_to_string(
 249     enum_definition: &hir::EnumDef<'_>,
 250     generics: &hir::Generics<'_>,
 251     name: Symbol,
 252     span: rustc_span::Span,
 253     visibility: &hir::Visibility<'_>,
 254 ) -> String {
 255     to_string(NO_ANN, |s| s.print_enum_def(enum_definition, generics, name, span, visibility))
 256 }
 257
 258 impl<'a> State<'a> {
 259     pub fn cbox(&mut self, u: usize) {
 260         self.s.cbox(u);
 261     }
 262
 263     pub fn nbsp(&mut self) {
 264         self.s.word(" ")
 265     }
 266
 267     pub fn word_nbsp<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 268         self.s.word(w);
 269         self.nbsp()
 270     }
 271
 272     pub fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 273         let w = w.into();
 274         // outer-box is consistent
 275         self.cbox(INDENT_UNIT);
 276         // head-box is inconsistent
 277         self.ibox(w.len() + 1);
 278         // keyword that starts the head
 279         if !w.is_empty() {
 280             self.word_nbsp(w);
 281         }
 282     }
 283
 284     pub fn bopen(&mut self) {
 285         self.s.word("{");
 286         self.end(); // close the head-box
 287     }
 288
 289     pub fn bclose_maybe_open(&mut self, span: rustc_span::Span, close_box: bool) {
 290         self.maybe_print_comment(span.hi());
 291         self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
 292         self.s.word("}");
 293         if close_box {
 294             self.end(); // close the outer-box
 295         }
 296     }
 297
 298     pub fn bclose(&mut self, span: rustc_span::Span) {
 299         self.bclose_maybe_open(span, true)
 300     }
 301
 302     pub fn space_if_not_bol(&mut self) {
 303         if !self.s.is_beginning_of_line() {
 304             self.s.space();
 305         }
 306     }
 307
 308     pub fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
 309         if !self.s.is_beginning_of_line() {
 310             self.s.break_offset(n, off)
 311         } else if off != 0 && self.s.last_token().is_hardbreak_tok() {
 312             // We do something pretty sketchy here: tuck the nonzero
 313             // offset-adjustment we were going to deposit along with the
 314             // break into the previous hardbreak.
 315             self.s.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 316         }
 317     }
 318
 319     // Synthesizes a comment that was not textually present in the original source
 320     // file.
 321     pub fn synth_comment(&mut self, text: String) {
 322         self.s.word("/*");
 323         self.s.space();
 324         self.s.word(text);
 325         self.s.space();
 326         self.s.word("*/")
 327     }
 328
 329     pub fn commasep_cmnt<T, F, G>(&mut self, b: Breaks, elts: &[T], mut op: F, mut get_span: G)
 330     where
 331         F: FnMut(&mut State<'_>, &T),
 332         G: FnMut(&T) -> rustc_span::Span,
 333     {
 334         self.rbox(0, b);
 335         let len = elts.len();
 336         let mut i = 0;
 337         for elt in elts {
 338             self.maybe_print_comment(get_span(elt).hi());
 339             op(self, elt);
 340             i += 1;
 341             if i < len {
 342                 self.s.word(",");
 343                 self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()));
 344                 self.space_if_not_bol();
 345             }
 346         }
 347         self.end();
 348     }
 349
 350     pub fn commasep_exprs(&mut self, b: Breaks, exprs: &[hir::Expr<'_>]) {
 351         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
 352     }
 353
 354     pub fn print_mod(&mut self, _mod: &hir::Mod<'_>, attrs: &[ast::Attribute]) {
 355         self.print_inner_attributes(attrs);
 356         for &item_id in _mod.item_ids {
 357             self.ann.nested(self, Nested::Item(item_id));
 358         }
 359     }
 360
 361     pub fn print_opt_lifetime(&mut self, lifetime: &hir::Lifetime) {
 362         if !lifetime.is_elided() {
 363             self.print_lifetime(lifetime);
 364             self.nbsp();
 365         }
 366     }
 367
 368     pub fn print_type(&mut self, ty: &hir::Ty<'_>) {
 369         self.maybe_print_comment(ty.span.lo());
 370         self.ibox(0);
 371         match ty.kind {
 372             hir::TyKind::Slice(ref ty) => {
 373                 self.s.word("[");
 374                 self.print_type(&ty);
 375                 self.s.word("]");
 376             }
 377             hir::TyKind::Ptr(ref mt) => {
 378                 self.s.word("*");
 379                 self.print_mt(mt, true);
 380             }
 381             hir::TyKind::Rptr(ref lifetime, ref mt) => {
 382                 self.s.word("&");
 383                 self.print_opt_lifetime(lifetime);
 384                 self.print_mt(mt, false);
 385             }
 386             hir::TyKind::Never => {
 387                 self.s.word("!");
 388             }
 389             hir::TyKind::Tup(ref elts) => {
 390                 self.popen();
 391                 self.commasep(Inconsistent, &elts[..], |s, ty| s.print_type(&ty));
 392                 if elts.len() == 1 {
 393                     self.s.word(",");
 394                 }
 395                 self.pclose();
 396             }
 397             hir::TyKind::BareFn(ref f) => {
 398                 self.print_ty_fn(
 399                     f.abi,
 400                     f.unsafety,
 401                     &f.decl,
 402                     None,
 403                     &f.generic_params,
 404                     f.param_names,
 405                 );
 406             }
 407             hir::TyKind::OpaqueDef(..) => self.s.word("/*impl Trait*/"),
 408             hir::TyKind::Path(ref qpath) => self.print_qpath(qpath, false),
 409             hir::TyKind::TraitObject(bounds, ref lifetime, syntax) => {
 410                 if syntax == ast::TraitObjectSyntax::Dyn {
 411                     self.word_space("dyn");
 412                 }
 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::Err => {
 442                 self.popen();
 443                 self.s.word("/*ERROR*/");
 444                 self.pclose();
 445             }
 446             hir::TyKind::Infer => {
 447                 self.s.word("_");
 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(self.attrs(item.hir_id()));
 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         let attrs = self.attrs(item.hir_id());
 565         self.print_outer_attributes(attrs);
 566         self.ann.pre(self, AnnNode::Item(item));
 567         match item.kind {
 568             hir::ItemKind::ExternCrate(orig_name) => {
 569                 self.head(visibility_qualified(&item.vis, "extern crate"));
 570                 if let Some(orig_name) = orig_name {
 571                     self.print_name(orig_name);
 572                     self.s.space();
 573                     self.s.word("as");
 574                     self.s.space();
 575                 }
 576                 self.print_ident(item.ident);
 577                 self.s.word(";");
 578                 self.end(); // end inner head-block
 579                 self.end(); // end outer head-block
 580             }
 581             hir::ItemKind::Use(ref path, kind) => {
 582                 self.head(visibility_qualified(&item.vis, "use"));
 583                 self.print_path(path, false);
 584
 585                 match kind {
 586                     hir::UseKind::Single => {
 587                         if path.segments.last().unwrap().ident != item.ident {
 588                             self.s.space();
 589                             self.word_space("as");
 590                             self.print_ident(item.ident);
 591                         }
 592                         self.s.word(";");
 593                     }
 594                     hir::UseKind::Glob => self.s.word("::*;"),
 595                     hir::UseKind::ListStem => self.s.word("::{};"),
 596                 }
 597                 self.end(); // end inner head-block
 598                 self.end(); // end outer head-block
 599             }
 600             hir::ItemKind::Static(ref ty, m, expr) => {
 601                 self.head(visibility_qualified(&item.vis, "static"));
 602                 if m == hir::Mutability::Mut {
 603                     self.word_space("mut");
 604                 }
 605                 self.print_ident(item.ident);
 606                 self.word_space(":");
 607                 self.print_type(&ty);
 608                 self.s.space();
 609                 self.end(); // end the head-ibox
 610
 611                 self.word_space("=");
 612                 self.ann.nested(self, Nested::Body(expr));
 613                 self.s.word(";");
 614                 self.end(); // end the outer cbox
 615             }
 616             hir::ItemKind::Const(ref ty, expr) => {
 617                 self.head(visibility_qualified(&item.vis, "const"));
 618                 self.print_ident(item.ident);
 619                 self.word_space(":");
 620                 self.print_type(&ty);
 621                 self.s.space();
 622                 self.end(); // end the head-ibox
 623
 624                 self.word_space("=");
 625                 self.ann.nested(self, Nested::Body(expr));
 626                 self.s.word(";");
 627                 self.end(); // end the outer cbox
 628             }
 629             hir::ItemKind::Fn(ref sig, ref param_names, body) => {
 630                 self.head("");
 631                 self.print_fn(
 632                     &sig.decl,
 633                     sig.header,
 634                     Some(item.ident.name),
 635                     param_names,
 636                     &item.vis,
 637                     &[],
 638                     Some(body),
 639                 );
 640                 self.s.word(" ");
 641                 self.end(); // need to close a box
 642                 self.end(); // need to close a box
 643                 self.ann.nested(self, Nested::Body(body));
 644             }
 645             hir::ItemKind::Mod(ref _mod) => {
 646                 self.head(visibility_qualified(&item.vis, "mod"));
 647                 self.print_ident(item.ident);
 648                 self.nbsp();
 649                 self.bopen();
 650                 self.print_mod(_mod, attrs);
 651                 self.bclose(item.span);
 652             }
 653             hir::ItemKind::ForeignMod { abi, items } => {
 654                 self.head("extern");
 655                 self.word_nbsp(abi.to_string());
 656                 self.bopen();
 657                 self.print_inner_attributes(self.attrs(item.hir_id()));
 658                 for item in items {
 659                     self.ann.nested(self, Nested::ForeignItem(item.id));
 660                 }
 661                 self.bclose(item.span);
 662             }
 663             hir::ItemKind::GlobalAsm(ref asm) => {
 664                 self.head(visibility_qualified(&item.vis, "global_asm!"));
 665                 self.print_inline_asm(asm);
 666                 self.end()
 667             }
 668             hir::ItemKind::TyAlias(ref ty, ref generics) => {
 669                 self.print_item_type(item, &generics, |state| {
 670                     state.word_space("=");
 671                     state.print_type(&ty);
 672                 });
 673             }
 674             hir::ItemKind::OpaqueTy(ref opaque_ty) => {
 675                 self.print_item_type(item, &opaque_ty.generics, |state| {
 676                     let mut real_bounds = Vec::with_capacity(opaque_ty.bounds.len());
 677                     for b in opaque_ty.bounds.iter() {
 678                         if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 679                             state.s.space();
 680                             state.word_space("for ?");
 681                             state.print_trait_ref(&ptr.trait_ref);
 682                         } else {
 683                             real_bounds.push(b);
 684                         }
 685                     }
 686                     state.print_bounds("= impl", real_bounds);
 687                 });
 688             }
 689             hir::ItemKind::Enum(ref enum_definition, ref params) => {
 690                 self.print_enum_def(enum_definition, params, item.ident.name, item.span, &item.vis);
 691             }
 692             hir::ItemKind::Struct(ref struct_def, ref generics) => {
 693                 self.head(visibility_qualified(&item.vis, "struct"));
 694                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
 695             }
 696             hir::ItemKind::Union(ref struct_def, ref generics) => {
 697                 self.head(visibility_qualified(&item.vis, "union"));
 698                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
 699             }
 700             hir::ItemKind::Impl(hir::Impl {
 701                 unsafety,
 702                 polarity,
 703                 defaultness,
 704                 constness,
 705                 defaultness_span: _,
 706                 ref generics,
 707                 ref of_trait,
 708                 ref self_ty,
 709                 items,
 710             }) => {
 711                 self.head("");
 712                 self.print_visibility(&item.vis);
 713                 self.print_defaultness(defaultness);
 714                 self.print_unsafety(unsafety);
 715                 self.word_nbsp("impl");
 716
 717                 if !generics.params.is_empty() {
 718                     self.print_generic_params(&generics.params);
 719                     self.s.space();
 720                 }
 721
 722                 if constness == hir::Constness::Const {
 723                     self.word_nbsp("const");
 724                 }
 725
 726                 if let hir::ImplPolarity::Negative(_) = polarity {
 727                     self.s.word("!");
 728                 }
 729
 730                 if let Some(ref t) = of_trait {
 731                     self.print_trait_ref(t);
 732                     self.s.space();
 733                     self.word_space("for");
 734                 }
 735
 736                 self.print_type(&self_ty);
 737                 self.print_where_clause(&generics.where_clause);
 738
 739                 self.s.space();
 740                 self.bopen();
 741                 self.print_inner_attributes(attrs);
 742                 for impl_item in items {
 743                     self.ann.nested(self, Nested::ImplItem(impl_item.id));
 744                 }
 745                 self.bclose(item.span);
 746             }
 747             hir::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, trait_items) => {
 748                 self.head("");
 749                 self.print_visibility(&item.vis);
 750                 self.print_is_auto(is_auto);
 751                 self.print_unsafety(unsafety);
 752                 self.word_nbsp("trait");
 753                 self.print_ident(item.ident);
 754                 self.print_generic_params(&generics.params);
 755                 let mut real_bounds = Vec::with_capacity(bounds.len());
 756                 for b in bounds.iter() {
 757                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 758                         self.s.space();
 759                         self.word_space("for ?");
 760                         self.print_trait_ref(&ptr.trait_ref);
 761                     } else {
 762                         real_bounds.push(b);
 763                     }
 764                 }
 765                 self.print_bounds(":", real_bounds);
 766                 self.print_where_clause(&generics.where_clause);
 767                 self.s.word(" ");
 768                 self.bopen();
 769                 for trait_item in trait_items {
 770                     self.ann.nested(self, Nested::TraitItem(trait_item.id));
 771                 }
 772                 self.bclose(item.span);
 773             }
 774             hir::ItemKind::TraitAlias(ref generics, ref bounds) => {
 775                 self.head("");
 776                 self.print_visibility(&item.vis);
 777                 self.word_nbsp("trait");
 778                 self.print_ident(item.ident);
 779                 self.print_generic_params(&generics.params);
 780                 let mut real_bounds = Vec::with_capacity(bounds.len());
 781                 // FIXME(durka) this seems to be some quite outdated syntax
 782                 for b in bounds.iter() {
 783                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
 784                         self.s.space();
 785                         self.word_space("for ?");
 786                         self.print_trait_ref(&ptr.trait_ref);
 787                     } else {
 788                         real_bounds.push(b);
 789                     }
 790                 }
 791                 self.nbsp();
 792                 self.print_bounds("=", real_bounds);
 793                 self.print_where_clause(&generics.where_clause);
 794                 self.s.word(";");
 795             }
 796         }
 797         self.ann.post(self, AnnNode::Item(item))
 798     }
 799
 800     pub fn print_trait_ref(&mut self, t: &hir::TraitRef<'_>) {
 801         self.print_path(&t.path, false)
 802     }
 803
 804     fn print_formal_generic_params(&mut self, generic_params: &[hir::GenericParam<'_>]) {
 805         if !generic_params.is_empty() {
 806             self.s.word("for");
 807             self.print_generic_params(generic_params);
 808             self.nbsp();
 809         }
 810     }
 811
 812     fn print_poly_trait_ref(&mut self, t: &hir::PolyTraitRef<'_>) {
 813         self.print_formal_generic_params(&t.bound_generic_params);
 814         self.print_trait_ref(&t.trait_ref)
 815     }
 816
 817     pub fn print_enum_def(
 818         &mut self,
 819         enum_definition: &hir::EnumDef<'_>,
 820         generics: &hir::Generics<'_>,
 821         name: Symbol,
 822         span: rustc_span::Span,
 823         visibility: &hir::Visibility<'_>,
 824     ) {
 825         self.head(visibility_qualified(visibility, "enum"));
 826         self.print_name(name);
 827         self.print_generic_params(&generics.params);
 828         self.print_where_clause(&generics.where_clause);
 829         self.s.space();
 830         self.print_variants(&enum_definition.variants, span)
 831     }
 832
 833     pub fn print_variants(&mut self, variants: &[hir::Variant<'_>], span: rustc_span::Span) {
 834         self.bopen();
 835         for v in variants {
 836             self.space_if_not_bol();
 837             self.maybe_print_comment(v.span.lo());
 838             self.print_outer_attributes(self.attrs(v.id));
 839             self.ibox(INDENT_UNIT);
 840             self.print_variant(v);
 841             self.s.word(",");
 842             self.end();
 843             self.maybe_print_trailing_comment(v.span, None);
 844         }
 845         self.bclose(span)
 846     }
 847
 848     pub fn print_visibility(&mut self, vis: &hir::Visibility<'_>) {
 849         match vis.node {
 850             hir::VisibilityKind::Public => self.word_nbsp("pub"),
 851             hir::VisibilityKind::Crate(ast::CrateSugar::JustCrate) => self.word_nbsp("crate"),
 852             hir::VisibilityKind::Crate(ast::CrateSugar::PubCrate) => self.word_nbsp("pub(crate)"),
 853             hir::VisibilityKind::Restricted { ref path, .. } => {
 854                 self.s.word("pub(");
 855                 if path.segments.len() == 1 && path.segments[0].ident.name == kw::Super {
 856                     // Special case: `super` can print like `pub(super)`.
 857                     self.s.word("super");
 858                 } else {
 859                     // Everything else requires `in` at present.
 860                     self.word_nbsp("in");
 861                     self.print_path(path, false);
 862                 }
 863                 self.word_nbsp(")");
 864             }
 865             hir::VisibilityKind::Inherited => (),
 866         }
 867     }
 868
 869     pub fn print_defaultness(&mut self, defaultness: hir::Defaultness) {
 870         match defaultness {
 871             hir::Defaultness::Default { .. } => self.word_nbsp("default"),
 872             hir::Defaultness::Final => (),
 873         }
 874     }
 875
 876     pub fn print_struct(
 877         &mut self,
 878         struct_def: &hir::VariantData<'_>,
 879         generics: &hir::Generics<'_>,
 880         name: Symbol,
 881         span: rustc_span::Span,
 882         print_finalizer: bool,
 883     ) {
 884         self.print_name(name);
 885         self.print_generic_params(&generics.params);
 886         match struct_def {
 887             hir::VariantData::Tuple(..) | hir::VariantData::Unit(..) => {
 888                 if let hir::VariantData::Tuple(..) = struct_def {
 889                     self.popen();
 890                     self.commasep(Inconsistent, struct_def.fields(), |s, field| {
 891                         s.maybe_print_comment(field.span.lo());
 892                         s.print_outer_attributes(s.attrs(field.hir_id));
 893                         s.print_visibility(&field.vis);
 894                         s.print_type(&field.ty)
 895                     });
 896                     self.pclose();
 897                 }
 898                 self.print_where_clause(&generics.where_clause);
 899                 if print_finalizer {
 900                     self.s.word(";");
 901                 }
 902                 self.end();
 903                 self.end() // close the outer-box
 904             }
 905             hir::VariantData::Struct(..) => {
 906                 self.print_where_clause(&generics.where_clause);
 907                 self.nbsp();
 908                 self.bopen();
 909                 self.hardbreak_if_not_bol();
 910
 911                 for field in struct_def.fields() {
 912                     self.hardbreak_if_not_bol();
 913                     self.maybe_print_comment(field.span.lo());
 914                     self.print_outer_attributes(self.attrs(field.hir_id));
 915                     self.print_visibility(&field.vis);
 916                     self.print_ident(field.ident);
 917                     self.word_nbsp(":");
 918                     self.print_type(&field.ty);
 919                     self.s.word(",");
 920                 }
 921
 922                 self.bclose(span)
 923             }
 924         }
 925     }
 926
 927     pub fn print_variant(&mut self, v: &hir::Variant<'_>) {
 928         self.head("");
 929         let generics = hir::Generics::empty();
 930         self.print_struct(&v.data, &generics, v.ident.name, v.span, false);
 931         if let Some(ref d) = v.disr_expr {
 932             self.s.space();
 933             self.word_space("=");
 934             self.print_anon_const(d);
 935         }
 936     }
 937     pub fn print_method_sig(
 938         &mut self,
 939         ident: Ident,
 940         m: &hir::FnSig<'_>,
 941         generics: &hir::Generics<'_>,
 942         vis: &hir::Visibility<'_>,
 943         arg_names: &[Ident],
 944         body_id: Option<hir::BodyId>,
 945     ) {
 946         self.print_fn(&m.decl, m.header, Some(ident.name), generics, vis, arg_names, body_id)
 947     }
 948
 949     pub fn print_trait_item(&mut self, ti: &hir::TraitItem<'_>) {
 950         self.ann.pre(self, AnnNode::SubItem(ti.hir_id()));
 951         self.hardbreak_if_not_bol();
 952         self.maybe_print_comment(ti.span.lo());
 953         self.print_outer_attributes(self.attrs(ti.hir_id()));
 954         match ti.kind {
 955             hir::TraitItemKind::Const(ref ty, default) => {
 956                 let vis =
 957                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
 958                 self.print_associated_const(ti.ident, &ty, default, &vis);
 959             }
 960             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(ref arg_names)) => {
 961                 let vis =
 962                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
 963                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, arg_names, None);
 964                 self.s.word(";");
 965             }
 966             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
 967                 let vis =
 968                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
 969                 self.head("");
 970                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, &[], Some(body));
 971                 self.nbsp();
 972                 self.end(); // need to close a box
 973                 self.end(); // need to close a box
 974                 self.ann.nested(self, Nested::Body(body));
 975             }
 976             hir::TraitItemKind::Type(ref bounds, ref default) => {
 977                 self.print_associated_type(
 978                     ti.ident,
 979                     &ti.generics,
 980                     Some(bounds),
 981                     default.as_ref().map(|ty| &**ty),
 982                 );
 983             }
 984         }
 985         self.ann.post(self, AnnNode::SubItem(ti.hir_id()))
 986     }
 987
 988     pub fn print_impl_item(&mut self, ii: &hir::ImplItem<'_>) {
 989         self.ann.pre(self, AnnNode::SubItem(ii.hir_id()));
 990         self.hardbreak_if_not_bol();
 991         self.maybe_print_comment(ii.span.lo());
 992         self.print_outer_attributes(self.attrs(ii.hir_id()));
 993         self.print_defaultness(ii.defaultness);
 994
 995         match ii.kind {
 996             hir::ImplItemKind::Const(ref ty, expr) => {
 997                 self.print_associated_const(ii.ident, &ty, Some(expr), &ii.vis);
 998             }
 999             hir::ImplItemKind::Fn(ref sig, body) => {
1000                 self.head("");
1001                 self.print_method_sig(ii.ident, sig, &ii.generics, &ii.vis, &[], Some(body));
1002                 self.nbsp();
1003                 self.end(); // need to close a box
1004                 self.end(); // need to close a box
1005                 self.ann.nested(self, Nested::Body(body));
1006             }
1007             hir::ImplItemKind::TyAlias(ref ty) => {
1008                 self.print_associated_type(ii.ident, &ii.generics, None, Some(ty));
1009             }
1010         }
1011         self.ann.post(self, AnnNode::SubItem(ii.hir_id()))
1012     }
1013
1014     pub fn print_local(&mut self, init: Option<&hir::Expr<'_>>, decl: impl Fn(&mut Self)) {
1015         self.space_if_not_bol();
1016         self.ibox(INDENT_UNIT);
1017         self.word_nbsp("let");
1018
1019         self.ibox(INDENT_UNIT);
1020         decl(self);
1021         self.end();
1022
1023         if let Some(ref init) = init {
1024             self.nbsp();
1025             self.word_space("=");
1026             self.print_expr(&init);
1027         }
1028         self.end()
1029     }
1030
1031     pub fn print_stmt(&mut self, st: &hir::Stmt<'_>) {
1032         self.maybe_print_comment(st.span.lo());
1033         match st.kind {
1034             hir::StmtKind::Local(ref loc) => {
1035                 self.print_local(loc.init.as_deref(), |this| this.print_local_decl(&loc));
1036             }
1037             hir::StmtKind::Item(item) => self.ann.nested(self, Nested::Item(item)),
1038             hir::StmtKind::Expr(ref expr) => {
1039                 self.space_if_not_bol();
1040                 self.print_expr(&expr);
1041             }
1042             hir::StmtKind::Semi(ref expr) => {
1043                 self.space_if_not_bol();
1044                 self.print_expr(&expr);
1045                 self.s.word(";");
1046             }
1047         }
1048         if stmt_ends_with_semi(&st.kind) {
1049             self.s.word(";");
1050         }
1051         self.maybe_print_trailing_comment(st.span, None)
1052     }
1053
1054     pub fn print_block(&mut self, blk: &hir::Block<'_>) {
1055         self.print_block_with_attrs(blk, &[])
1056     }
1057
1058     pub fn print_block_unclosed(&mut self, blk: &hir::Block<'_>) {
1059         self.print_block_maybe_unclosed(blk, &[], false)
1060     }
1061
1062     pub fn print_block_with_attrs(&mut self, blk: &hir::Block<'_>, attrs: &[ast::Attribute]) {
1063         self.print_block_maybe_unclosed(blk, attrs, true)
1064     }
1065
1066     pub fn print_block_maybe_unclosed(
1067         &mut self,
1068         blk: &hir::Block<'_>,
1069         attrs: &[ast::Attribute],
1070         close_box: bool,
1071     ) {
1072         match blk.rules {
1073             hir::BlockCheckMode::UnsafeBlock(..) => self.word_space("unsafe"),
1074             hir::BlockCheckMode::DefaultBlock => (),
1075         }
1076         self.maybe_print_comment(blk.span.lo());
1077         self.ann.pre(self, AnnNode::Block(blk));
1078         self.bopen();
1079
1080         self.print_inner_attributes(attrs);
1081
1082         for st in blk.stmts {
1083             self.print_stmt(st);
1084         }
1085         if let Some(ref expr) = blk.expr {
1086             self.space_if_not_bol();
1087             self.print_expr(&expr);
1088             self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
1089         }
1090         self.bclose_maybe_open(blk.span, close_box);
1091         self.ann.post(self, AnnNode::Block(blk))
1092     }
1093
1094     fn print_else(&mut self, els: Option<&hir::Expr<'_>>) {
1095         match els {
1096             Some(else_) => {
1097                 match else_.kind {
1098                     // "another else-if"
1099                     hir::ExprKind::If(ref i, ref then, ref e) => {
1100                         self.cbox(INDENT_UNIT - 1);
1101                         self.ibox(0);
1102                         self.s.word(" else if ");
1103                         self.print_expr_as_cond(&i);
1104                         self.s.space();
1105                         self.print_expr(&then);
1106                         self.print_else(e.as_ref().map(|e| &**e))
1107                     }
1108                     // "final else"
1109                     hir::ExprKind::Block(ref b, _) => {
1110                         self.cbox(INDENT_UNIT - 1);
1111                         self.ibox(0);
1112                         self.s.word(" else ");
1113                         self.print_block(&b)
1114                     }
1115                     hir::ExprKind::Match(ref expr, arms, _) => {
1116                         // else if let desugared to match
1117                         assert!(arms.len() == 2, "if let desugars to match with two arms");
1118
1119                         self.s.word(" else ");
1120                         self.s.word("{");
1121
1122                         self.cbox(INDENT_UNIT);
1123                         self.ibox(INDENT_UNIT);
1124                         self.word_nbsp("match");
1125                         self.print_expr_as_cond(&expr);
1126                         self.s.space();
1127                         self.bopen();
1128                         for arm in arms {
1129                             self.print_arm(arm);
1130                         }
1131                         self.bclose(expr.span);
1132
1133                         self.s.word("}");
1134                     }
1135                     // BLEAH, constraints would be great here
1136                     _ => {
1137                         panic!("print_if saw if with weird alternative");
1138                     }
1139                 }
1140             }
1141             _ => {}
1142         }
1143     }
1144
1145     pub fn print_if(
1146         &mut self,
1147         test: &hir::Expr<'_>,
1148         blk: &hir::Expr<'_>,
1149         elseopt: Option<&hir::Expr<'_>>,
1150     ) {
1151         self.head("if");
1152         self.print_expr_as_cond(test);
1153         self.s.space();
1154         self.print_expr(blk);
1155         self.print_else(elseopt)
1156     }
1157
1158     pub fn print_anon_const(&mut self, constant: &hir::AnonConst) {
1159         self.ann.nested(self, Nested::Body(constant.body))
1160     }
1161
1162     fn print_call_post(&mut self, args: &[hir::Expr<'_>]) {
1163         self.popen();
1164         self.commasep_exprs(Inconsistent, args);
1165         self.pclose()
1166     }
1167
1168     pub fn print_expr_maybe_paren(&mut self, expr: &hir::Expr<'_>, prec: i8) {
1169         let needs_par = expr.precedence().order() < prec;
1170         if needs_par {
1171             self.popen();
1172         }
1173         self.print_expr(expr);
1174         if needs_par {
1175             self.pclose();
1176         }
1177     }
1178
1179     /// Print an expr using syntax that's acceptable in a condition position, such as the `cond` in
1180     /// `if cond { ... }`.
1181     pub fn print_expr_as_cond(&mut self, expr: &hir::Expr<'_>) {
1182         let needs_par = match expr.kind {
1183             // These cases need parens due to the parse error observed in #26461: `if return {}`
1184             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1185             hir::ExprKind::Closure(..) | hir::ExprKind::Ret(..) | hir::ExprKind::Break(..) => true,
1186
1187             _ => contains_exterior_struct_lit(expr),
1188         };
1189
1190         if needs_par {
1191             self.popen();
1192         }
1193         self.print_expr(expr);
1194         if needs_par {
1195             self.pclose();
1196         }
1197     }
1198
1199     fn print_expr_vec(&mut self, exprs: &[hir::Expr<'_>]) {
1200         self.ibox(INDENT_UNIT);
1201         self.s.word("[");
1202         self.commasep_exprs(Inconsistent, exprs);
1203         self.s.word("]");
1204         self.end()
1205     }
1206
1207     fn print_expr_anon_const(&mut self, anon_const: &hir::AnonConst) {
1208         self.ibox(INDENT_UNIT);
1209         self.s.word_space("const");
1210         self.print_anon_const(anon_const);
1211         self.end()
1212     }
1213
1214     fn print_expr_repeat(&mut self, element: &hir::Expr<'_>, count: &hir::AnonConst) {
1215         self.ibox(INDENT_UNIT);
1216         self.s.word("[");
1217         self.print_expr(element);
1218         self.word_space(";");
1219         self.print_anon_const(count);
1220         self.s.word("]");
1221         self.end()
1222     }
1223
1224     fn print_expr_struct(
1225         &mut self,
1226         qpath: &hir::QPath<'_>,
1227         fields: &[hir::ExprField<'_>],
1228         wth: &Option<&hir::Expr<'_>>,
1229     ) {
1230         self.print_qpath(qpath, true);
1231         self.s.word("{");
1232         self.commasep_cmnt(
1233             Consistent,
1234             fields,
1235             |s, field| {
1236                 s.ibox(INDENT_UNIT);
1237                 if !field.is_shorthand {
1238                     s.print_ident(field.ident);
1239                     s.word_space(":");
1240                 }
1241                 s.print_expr(&field.expr);
1242                 s.end()
1243             },
1244             |f| f.span,
1245         );
1246         match *wth {
1247             Some(ref expr) => {
1248                 self.ibox(INDENT_UNIT);
1249                 if !fields.is_empty() {
1250                     self.s.word(",");
1251                     self.s.space();
1252                 }
1253                 self.s.word("..");
1254                 self.print_expr(&expr);
1255                 self.end();
1256             }
1257             _ => {
1258                 if !fields.is_empty() {
1259                     self.s.word(",")
1260                 }
1261             }
1262         }
1263         self.s.word("}");
1264     }
1265
1266     fn print_expr_tup(&mut self, exprs: &[hir::Expr<'_>]) {
1267         self.popen();
1268         self.commasep_exprs(Inconsistent, exprs);
1269         if exprs.len() == 1 {
1270             self.s.word(",");
1271         }
1272         self.pclose()
1273     }
1274
1275     fn print_expr_call(&mut self, func: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
1276         let prec = match func.kind {
1277             hir::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1278             _ => parser::PREC_POSTFIX,
1279         };
1280
1281         self.print_expr_maybe_paren(func, prec);
1282         self.print_call_post(args)
1283     }
1284
1285     fn print_expr_method_call(&mut self, segment: &hir::PathSegment<'_>, args: &[hir::Expr<'_>]) {
1286         let base_args = &args[1..];
1287         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
1288         self.s.word(".");
1289         self.print_ident(segment.ident);
1290
1291         let generic_args = segment.args();
1292         if !generic_args.args.is_empty() || !generic_args.bindings.is_empty() {
1293             self.print_generic_args(generic_args, segment.infer_args, true);
1294         }
1295
1296         self.print_call_post(base_args)
1297     }
1298
1299     fn print_expr_binary(&mut self, op: hir::BinOp, lhs: &hir::Expr<'_>, rhs: &hir::Expr<'_>) {
1300         let assoc_op = bin_op_to_assoc_op(op.node);
1301         let prec = assoc_op.precedence() as i8;
1302         let fixity = assoc_op.fixity();
1303
1304         let (left_prec, right_prec) = match fixity {
1305             Fixity::Left => (prec, prec + 1),
1306             Fixity::Right => (prec + 1, prec),
1307             Fixity::None => (prec + 1, prec + 1),
1308         };
1309
1310         let left_prec = match (&lhs.kind, op.node) {
1311             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1312             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1313             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1314             (&hir::ExprKind::Cast { .. }, hir::BinOpKind::Lt | hir::BinOpKind::Shl) => {
1315                 parser::PREC_FORCE_PAREN
1316             }
1317             _ => left_prec,
1318         };
1319
1320         self.print_expr_maybe_paren(lhs, left_prec);
1321         self.s.space();
1322         self.word_space(op.node.as_str());
1323         self.print_expr_maybe_paren(rhs, right_prec)
1324     }
1325
1326     fn print_expr_unary(&mut self, op: hir::UnOp, expr: &hir::Expr<'_>) {
1327         self.s.word(op.as_str());
1328         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1329     }
1330
1331     fn print_expr_addr_of(
1332         &mut self,
1333         kind: hir::BorrowKind,
1334         mutability: hir::Mutability,
1335         expr: &hir::Expr<'_>,
1336     ) {
1337         self.s.word("&");
1338         match kind {
1339             hir::BorrowKind::Ref => self.print_mutability(mutability, false),
1340             hir::BorrowKind::Raw => {
1341                 self.word_nbsp("raw");
1342                 self.print_mutability(mutability, true);
1343             }
1344         }
1345         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1346     }
1347
1348     fn print_literal(&mut self, lit: &hir::Lit) {
1349         self.maybe_print_comment(lit.span.lo());
1350         self.word(lit.node.to_lit_token().to_string())
1351     }
1352
1353     fn print_inline_asm(&mut self, asm: &hir::InlineAsm<'_>) {
1354         enum AsmArg<'a> {
1355             Template(String),
1356             Operand(&'a hir::InlineAsmOperand<'a>),
1357             Options(ast::InlineAsmOptions),
1358         }
1359
1360         let mut args = vec![];
1361         args.push(AsmArg::Template(ast::InlineAsmTemplatePiece::to_string(&asm.template)));
1362         args.extend(asm.operands.iter().map(|(o, _)| AsmArg::Operand(o)));
1363         if !asm.options.is_empty() {
1364             args.push(AsmArg::Options(asm.options));
1365         }
1366
1367         self.popen();
1368         self.commasep(Consistent, &args, |s, arg| match arg {
1369             AsmArg::Template(template) => s.print_string(&template, ast::StrStyle::Cooked),
1370             AsmArg::Operand(op) => match op {
1371                 hir::InlineAsmOperand::In { reg, expr } => {
1372                     s.word("in");
1373                     s.popen();
1374                     s.word(format!("{}", reg));
1375                     s.pclose();
1376                     s.space();
1377                     s.print_expr(expr);
1378                 }
1379                 hir::InlineAsmOperand::Out { reg, late, expr } => {
1380                     s.word(if *late { "lateout" } else { "out" });
1381                     s.popen();
1382                     s.word(format!("{}", reg));
1383                     s.pclose();
1384                     s.space();
1385                     match expr {
1386                         Some(expr) => s.print_expr(expr),
1387                         None => s.word("_"),
1388                     }
1389                 }
1390                 hir::InlineAsmOperand::InOut { reg, late, expr } => {
1391                     s.word(if *late { "inlateout" } else { "inout" });
1392                     s.popen();
1393                     s.word(format!("{}", reg));
1394                     s.pclose();
1395                     s.space();
1396                     s.print_expr(expr);
1397                 }
1398                 hir::InlineAsmOperand::SplitInOut { reg, late, in_expr, out_expr } => {
1399                     s.word(if *late { "inlateout" } else { "inout" });
1400                     s.popen();
1401                     s.word(format!("{}", reg));
1402                     s.pclose();
1403                     s.space();
1404                     s.print_expr(in_expr);
1405                     s.space();
1406                     s.word_space("=>");
1407                     match out_expr {
1408                         Some(out_expr) => s.print_expr(out_expr),
1409                         None => s.word("_"),
1410                     }
1411                 }
1412                 hir::InlineAsmOperand::Const { anon_const } => {
1413                     s.word("const");
1414                     s.space();
1415                     s.print_anon_const(anon_const);
1416                 }
1417                 hir::InlineAsmOperand::Sym { expr } => {
1418                     s.word("sym");
1419                     s.space();
1420                     s.print_expr(expr);
1421                 }
1422             },
1423             AsmArg::Options(opts) => {
1424                 s.word("options");
1425                 s.popen();
1426                 let mut options = vec![];
1427                 if opts.contains(ast::InlineAsmOptions::PURE) {
1428                     options.push("pure");
1429                 }
1430                 if opts.contains(ast::InlineAsmOptions::NOMEM) {
1431                     options.push("nomem");
1432                 }
1433                 if opts.contains(ast::InlineAsmOptions::READONLY) {
1434                     options.push("readonly");
1435                 }
1436                 if opts.contains(ast::InlineAsmOptions::PRESERVES_FLAGS) {
1437                     options.push("preserves_flags");
1438                 }
1439                 if opts.contains(ast::InlineAsmOptions::NORETURN) {
1440                     options.push("noreturn");
1441                 }
1442                 if opts.contains(ast::InlineAsmOptions::NOSTACK) {
1443                     options.push("nostack");
1444                 }
1445                 if opts.contains(ast::InlineAsmOptions::ATT_SYNTAX) {
1446                     options.push("att_syntax");
1447                 }
1448                 if opts.contains(ast::InlineAsmOptions::RAW) {
1449                     options.push("raw");
1450                 }
1451                 s.commasep(Inconsistent, &options, |s, &opt| {
1452                     s.word(opt);
1453                 });
1454                 s.pclose();
1455             }
1456         });
1457         self.pclose();
1458     }
1459
1460     pub fn print_expr(&mut self, expr: &hir::Expr<'_>) {
1461         self.maybe_print_comment(expr.span.lo());
1462         self.print_outer_attributes(self.attrs(expr.hir_id));
1463         self.ibox(INDENT_UNIT);
1464         self.ann.pre(self, AnnNode::Expr(expr));
1465         match expr.kind {
1466             hir::ExprKind::Box(ref expr) => {
1467                 self.word_space("box");
1468                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX);
1469             }
1470             hir::ExprKind::Array(ref exprs) => {
1471                 self.print_expr_vec(exprs);
1472             }
1473             hir::ExprKind::ConstBlock(ref anon_const) => {
1474                 self.print_expr_anon_const(anon_const);
1475             }
1476             hir::ExprKind::Repeat(ref element, ref count) => {
1477                 self.print_expr_repeat(&element, count);
1478             }
1479             hir::ExprKind::Struct(ref qpath, fields, ref wth) => {
1480                 self.print_expr_struct(qpath, fields, wth);
1481             }
1482             hir::ExprKind::Tup(ref exprs) => {
1483                 self.print_expr_tup(exprs);
1484             }
1485             hir::ExprKind::Call(ref func, ref args) => {
1486                 self.print_expr_call(&func, args);
1487             }
1488             hir::ExprKind::MethodCall(ref segment, _, ref args, _) => {
1489                 self.print_expr_method_call(segment, args);
1490             }
1491             hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
1492                 self.print_expr_binary(op, &lhs, &rhs);
1493             }
1494             hir::ExprKind::Unary(op, ref expr) => {
1495                 self.print_expr_unary(op, &expr);
1496             }
1497             hir::ExprKind::AddrOf(k, m, ref expr) => {
1498                 self.print_expr_addr_of(k, m, &expr);
1499             }
1500             hir::ExprKind::Lit(ref lit) => {
1501                 self.print_literal(&lit);
1502             }
1503             hir::ExprKind::Cast(ref expr, ref ty) => {
1504                 let prec = AssocOp::As.precedence() as i8;
1505                 self.print_expr_maybe_paren(&expr, prec);
1506                 self.s.space();
1507                 self.word_space("as");
1508                 self.print_type(&ty);
1509             }
1510             hir::ExprKind::Type(ref expr, ref ty) => {
1511                 let prec = AssocOp::Colon.precedence() as i8;
1512                 self.print_expr_maybe_paren(&expr, prec);
1513                 self.word_space(":");
1514                 self.print_type(&ty);
1515             }
1516             hir::ExprKind::DropTemps(ref init) => {
1517                 // Print `{`:
1518                 self.cbox(INDENT_UNIT);
1519                 self.ibox(0);
1520                 self.bopen();
1521
1522                 // Print `let _t = $init;`:
1523                 let temp = Ident::from_str("_t");
1524                 self.print_local(Some(init), |this| this.print_ident(temp));
1525                 self.s.word(";");
1526
1527                 // Print `_t`:
1528                 self.space_if_not_bol();
1529                 self.print_ident(temp);
1530
1531                 // Print `}`:
1532                 self.bclose_maybe_open(expr.span, true);
1533             }
1534             hir::ExprKind::If(ref test, ref blk, ref elseopt) => {
1535                 self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e));
1536             }
1537             hir::ExprKind::Loop(ref blk, opt_label, _, _) => {
1538                 if let Some(label) = opt_label {
1539                     self.print_ident(label.ident);
1540                     self.word_space(":");
1541                 }
1542                 self.head("loop");
1543                 self.print_block(&blk);
1544             }
1545             hir::ExprKind::Match(ref expr, arms, _) => {
1546                 self.cbox(INDENT_UNIT);
1547                 self.ibox(INDENT_UNIT);
1548                 self.word_nbsp("match");
1549                 self.print_expr_as_cond(&expr);
1550                 self.s.space();
1551                 self.bopen();
1552                 for arm in arms {
1553                     self.print_arm(arm);
1554                 }
1555                 self.bclose(expr.span);
1556             }
1557             hir::ExprKind::Closure(capture_clause, ref decl, body, _fn_decl_span, _gen) => {
1558                 self.print_capture_clause(capture_clause);
1559
1560                 self.print_closure_params(&decl, body);
1561                 self.s.space();
1562
1563                 // This is a bare expression.
1564                 self.ann.nested(self, Nested::Body(body));
1565                 self.end(); // need to close a box
1566
1567                 // A box will be closed by `print_expr`, but we didn't want an overall
1568                 // wrapper so we closed the corresponding opening. so create an
1569                 // empty box to satisfy the close.
1570                 self.ibox(0);
1571             }
1572             hir::ExprKind::Block(ref blk, opt_label) => {
1573                 if let Some(label) = opt_label {
1574                     self.print_ident(label.ident);
1575                     self.word_space(":");
1576                 }
1577                 // containing cbox, will be closed by print-block at `}`
1578                 self.cbox(INDENT_UNIT);
1579                 // head-box, will be closed by print-block after `{`
1580                 self.ibox(0);
1581                 self.print_block(&blk);
1582             }
1583             hir::ExprKind::Assign(ref lhs, ref rhs, _) => {
1584                 let prec = AssocOp::Assign.precedence() as i8;
1585                 self.print_expr_maybe_paren(&lhs, prec + 1);
1586                 self.s.space();
1587                 self.word_space("=");
1588                 self.print_expr_maybe_paren(&rhs, prec);
1589             }
1590             hir::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
1591                 let prec = AssocOp::Assign.precedence() as i8;
1592                 self.print_expr_maybe_paren(&lhs, prec + 1);
1593                 self.s.space();
1594                 self.s.word(op.node.as_str());
1595                 self.word_space("=");
1596                 self.print_expr_maybe_paren(&rhs, prec);
1597             }
1598             hir::ExprKind::Field(ref expr, ident) => {
1599                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
1600                 self.s.word(".");
1601                 self.print_ident(ident);
1602             }
1603             hir::ExprKind::Index(ref expr, ref index) => {
1604                 self.print_expr_maybe_paren(&expr, parser::PREC_POSTFIX);
1605                 self.s.word("[");
1606                 self.print_expr(&index);
1607                 self.s.word("]");
1608             }
1609             hir::ExprKind::Path(ref qpath) => self.print_qpath(qpath, true),
1610             hir::ExprKind::Break(destination, ref opt_expr) => {
1611                 self.s.word("break");
1612                 self.s.space();
1613                 if let Some(label) = destination.label {
1614                     self.print_ident(label.ident);
1615                     self.s.space();
1616                 }
1617                 if let Some(ref expr) = *opt_expr {
1618                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
1619                     self.s.space();
1620                 }
1621             }
1622             hir::ExprKind::Continue(destination) => {
1623                 self.s.word("continue");
1624                 self.s.space();
1625                 if let Some(label) = destination.label {
1626                     self.print_ident(label.ident);
1627                     self.s.space()
1628                 }
1629             }
1630             hir::ExprKind::Ret(ref result) => {
1631                 self.s.word("return");
1632                 if let Some(ref expr) = *result {
1633                     self.s.word(" ");
1634                     self.print_expr_maybe_paren(&expr, parser::PREC_JUMP);
1635                 }
1636             }
1637             hir::ExprKind::InlineAsm(ref asm) => {
1638                 self.word("asm!");
1639                 self.print_inline_asm(asm);
1640             }
1641             hir::ExprKind::LlvmInlineAsm(ref a) => {
1642                 let i = &a.inner;
1643                 self.s.word("llvm_asm!");
1644                 self.popen();
1645                 self.print_symbol(i.asm, i.asm_str_style);
1646                 self.word_space(":");
1647
1648                 let mut out_idx = 0;
1649                 self.commasep(Inconsistent, &i.outputs, |s, out| {
1650                     let constraint = out.constraint.as_str();
1651                     let mut ch = constraint.chars();
1652                     match ch.next() {
1653                         Some('=') if out.is_rw => {
1654                             s.print_string(&format!("+{}", ch.as_str()), ast::StrStyle::Cooked)
1655                         }
1656                         _ => s.print_string(&constraint, ast::StrStyle::Cooked),
1657                     }
1658                     s.popen();
1659                     s.print_expr(&a.outputs_exprs[out_idx]);
1660                     s.pclose();
1661                     out_idx += 1;
1662                 });
1663                 self.s.space();
1664                 self.word_space(":");
1665
1666                 let mut in_idx = 0;
1667                 self.commasep(Inconsistent, &i.inputs, |s, &co| {
1668                     s.print_symbol(co, ast::StrStyle::Cooked);
1669                     s.popen();
1670                     s.print_expr(&a.inputs_exprs[in_idx]);
1671                     s.pclose();
1672                     in_idx += 1;
1673                 });
1674                 self.s.space();
1675                 self.word_space(":");
1676
1677                 self.commasep(Inconsistent, &i.clobbers, |s, &co| {
1678                     s.print_symbol(co, ast::StrStyle::Cooked);
1679                 });
1680
1681                 let mut options = vec![];
1682                 if i.volatile {
1683                     options.push("volatile");
1684                 }
1685                 if i.alignstack {
1686                     options.push("alignstack");
1687                 }
1688                 if i.dialect == ast::LlvmAsmDialect::Intel {
1689                     options.push("intel");
1690                 }
1691
1692                 if !options.is_empty() {
1693                     self.s.space();
1694                     self.word_space(":");
1695                     self.commasep(Inconsistent, &options, |s, &co| {
1696                         s.print_string(co, ast::StrStyle::Cooked);
1697                     });
1698                 }
1699
1700                 self.pclose();
1701             }
1702             hir::ExprKind::Yield(ref expr, _) => {
1703                 self.word_space("yield");
1704                 self.print_expr_maybe_paren(&expr, parser::PREC_JUMP);
1705             }
1706             hir::ExprKind::Err => {
1707                 self.popen();
1708                 self.s.word("/*ERROR*/");
1709                 self.pclose();
1710             }
1711         }
1712         self.ann.post(self, AnnNode::Expr(expr));
1713         self.end()
1714     }
1715
1716     pub fn print_local_decl(&mut self, loc: &hir::Local<'_>) {
1717         self.print_pat(&loc.pat);
1718         if let Some(ref ty) = loc.ty {
1719             self.word_space(":");
1720             self.print_type(&ty);
1721         }
1722     }
1723
1724     pub fn print_name(&mut self, name: Symbol) {
1725         self.print_ident(Ident::with_dummy_span(name))
1726     }
1727
1728     pub fn print_path(&mut self, path: &hir::Path<'_>, colons_before_params: bool) {
1729         self.maybe_print_comment(path.span.lo());
1730
1731         for (i, segment) in path.segments.iter().enumerate() {
1732             if i > 0 {
1733                 self.s.word("::")
1734             }
1735             if segment.ident.name != kw::PathRoot {
1736                 self.print_ident(segment.ident);
1737                 self.print_generic_args(segment.args(), segment.infer_args, colons_before_params);
1738             }
1739         }
1740     }
1741
1742     pub fn print_path_segment(&mut self, segment: &hir::PathSegment<'_>) {
1743         if segment.ident.name != kw::PathRoot {
1744             self.print_ident(segment.ident);
1745             self.print_generic_args(segment.args(), segment.infer_args, false);
1746         }
1747     }
1748
1749     pub fn print_qpath(&mut self, qpath: &hir::QPath<'_>, colons_before_params: bool) {
1750         match *qpath {
1751             hir::QPath::Resolved(None, ref path) => self.print_path(path, colons_before_params),
1752             hir::QPath::Resolved(Some(ref qself), ref path) => {
1753                 self.s.word("<");
1754                 self.print_type(qself);
1755                 self.s.space();
1756                 self.word_space("as");
1757
1758                 for (i, segment) in path.segments[..path.segments.len() - 1].iter().enumerate() {
1759                     if i > 0 {
1760                         self.s.word("::")
1761                     }
1762                     if segment.ident.name != kw::PathRoot {
1763                         self.print_ident(segment.ident);
1764                         self.print_generic_args(
1765                             segment.args(),
1766                             segment.infer_args,
1767                             colons_before_params,
1768                         );
1769                     }
1770                 }
1771
1772                 self.s.word(">");
1773                 self.s.word("::");
1774                 let item_segment = path.segments.last().unwrap();
1775                 self.print_ident(item_segment.ident);
1776                 self.print_generic_args(
1777                     item_segment.args(),
1778                     item_segment.infer_args,
1779                     colons_before_params,
1780                 )
1781             }
1782             hir::QPath::TypeRelative(ref qself, ref item_segment) => {
1783                 // If we've got a compound-qualified-path, let's push an additional pair of angle
1784                 // brackets, so that we pretty-print `<<A::B>::C>` as `<A::B>::C`, instead of just
1785                 // `A::B::C` (since the latter could be ambiguous to the user)
1786                 if let hir::TyKind::Path(hir::QPath::Resolved(None, _)) = &qself.kind {
1787                     self.print_type(qself);
1788                 } else {
1789                     self.s.word("<");
1790                     self.print_type(qself);
1791                     self.s.word(">");
1792                 }
1793
1794                 self.s.word("::");
1795                 self.print_ident(item_segment.ident);
1796                 self.print_generic_args(
1797                     item_segment.args(),
1798                     item_segment.infer_args,
1799                     colons_before_params,
1800                 )
1801             }
1802             hir::QPath::LangItem(lang_item, span) => {
1803                 self.s.word("#[lang = \"");
1804                 self.print_ident(Ident::new(lang_item.name(), span));
1805                 self.s.word("\"]");
1806             }
1807         }
1808     }
1809
1810     fn print_generic_args(
1811         &mut self,
1812         generic_args: &hir::GenericArgs<'_>,
1813         infer_args: bool,
1814         colons_before_params: bool,
1815     ) {
1816         if generic_args.parenthesized {
1817             self.s.word("(");
1818             self.commasep(Inconsistent, generic_args.inputs(), |s, ty| s.print_type(&ty));
1819             self.s.word(")");
1820
1821             self.space_if_not_bol();
1822             self.word_space("->");
1823             self.print_type(generic_args.bindings[0].ty());
1824         } else {
1825             let start = if colons_before_params { "::<" } else { "<" };
1826             let empty = Cell::new(true);
1827             let start_or_comma = |this: &mut Self| {
1828                 if empty.get() {
1829                     empty.set(false);
1830                     this.s.word(start)
1831                 } else {
1832                     this.word_space(",")
1833                 }
1834             };
1835
1836             let mut nonelided_generic_args: bool = false;
1837             let elide_lifetimes = generic_args.args.iter().all(|arg| match arg {
1838                 GenericArg::Lifetime(lt) => lt.is_elided(),
1839                 _ => {
1840                     nonelided_generic_args = true;
1841                     true
1842                 }
1843             });
1844
1845             if nonelided_generic_args {
1846                 start_or_comma(self);
1847                 self.commasep(
1848                     Inconsistent,
1849                     &generic_args.args,
1850                     |s, generic_arg| match generic_arg {
1851                         GenericArg::Lifetime(lt) if !elide_lifetimes => s.print_lifetime(lt),
1852                         GenericArg::Lifetime(_) => {}
1853                         GenericArg::Type(ty) => s.print_type(ty),
1854                         GenericArg::Const(ct) => s.print_anon_const(&ct.value),
1855                         GenericArg::Infer(_inf) => s.word("_"),
1856                     },
1857                 );
1858             }
1859
1860             // FIXME(eddyb): this would leak into error messages (e.g.,
1861             // "non-exhaustive patterns: `Some::<..>(_)` not covered").
1862             if infer_args && false {
1863                 start_or_comma(self);
1864                 self.s.word("..");
1865             }
1866
1867             for binding in generic_args.bindings.iter() {
1868                 start_or_comma(self);
1869                 self.print_ident(binding.ident);
1870                 self.print_generic_args(binding.gen_args, false, false);
1871                 self.s.space();
1872                 match generic_args.bindings[0].kind {
1873                     hir::TypeBindingKind::Equality { ref ty } => {
1874                         self.word_space("=");
1875                         self.print_type(ty);
1876                     }
1877                     hir::TypeBindingKind::Constraint { bounds } => {
1878                         self.print_bounds(":", bounds);
1879                     }
1880                 }
1881             }
1882
1883             if !empty.get() {
1884                 self.s.word(">")
1885             }
1886         }
1887     }
1888
1889     pub fn print_pat(&mut self, pat: &hir::Pat<'_>) {
1890         self.maybe_print_comment(pat.span.lo());
1891         self.ann.pre(self, AnnNode::Pat(pat));
1892         // Pat isn't normalized, but the beauty of it
1893         // is that it doesn't matter
1894         match pat.kind {
1895             PatKind::Wild => self.s.word("_"),
1896             PatKind::Binding(binding_mode, _, ident, ref sub) => {
1897                 match binding_mode {
1898                     hir::BindingAnnotation::Ref => {
1899                         self.word_nbsp("ref");
1900                         self.print_mutability(hir::Mutability::Not, false);
1901                     }
1902                     hir::BindingAnnotation::RefMut => {
1903                         self.word_nbsp("ref");
1904                         self.print_mutability(hir::Mutability::Mut, false);
1905                     }
1906                     hir::BindingAnnotation::Unannotated => {}
1907                     hir::BindingAnnotation::Mutable => {
1908                         self.word_nbsp("mut");
1909                     }
1910                 }
1911                 self.print_ident(ident);
1912                 if let Some(ref p) = *sub {
1913                     self.s.word("@");
1914                     self.print_pat(&p);
1915                 }
1916             }
1917             PatKind::TupleStruct(ref qpath, ref elts, ddpos) => {
1918                 self.print_qpath(qpath, true);
1919                 self.popen();
1920                 if let Some(ddpos) = ddpos {
1921                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p));
1922                     if ddpos != 0 {
1923                         self.word_space(",");
1924                     }
1925                     self.s.word("..");
1926                     if ddpos != elts.len() {
1927                         self.s.word(",");
1928                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p));
1929                     }
1930                 } else {
1931                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p));
1932                 }
1933                 self.pclose();
1934             }
1935             PatKind::Path(ref qpath) => {
1936                 self.print_qpath(qpath, true);
1937             }
1938             PatKind::Struct(ref qpath, ref fields, etc) => {
1939                 self.print_qpath(qpath, true);
1940                 self.nbsp();
1941                 self.word_space("{");
1942                 self.commasep_cmnt(
1943                     Consistent,
1944                     &fields[..],
1945                     |s, f| {
1946                         s.cbox(INDENT_UNIT);
1947                         if !f.is_shorthand {
1948                             s.print_ident(f.ident);
1949                             s.word_nbsp(":");
1950                         }
1951                         s.print_pat(&f.pat);
1952                         s.end()
1953                     },
1954                     |f| f.pat.span,
1955                 );
1956                 if etc {
1957                     if !fields.is_empty() {
1958                         self.word_space(",");
1959                     }
1960                     self.s.word("..");
1961                 }
1962                 self.s.space();
1963                 self.s.word("}");
1964             }
1965             PatKind::Or(ref pats) => {
1966                 self.strsep("|", true, Inconsistent, &pats[..], |s, p| s.print_pat(&p));
1967             }
1968             PatKind::Tuple(ref elts, ddpos) => {
1969                 self.popen();
1970                 if let Some(ddpos) = ddpos {
1971                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p));
1972                     if ddpos != 0 {
1973                         self.word_space(",");
1974                     }
1975                     self.s.word("..");
1976                     if ddpos != elts.len() {
1977                         self.s.word(",");
1978                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p));
1979                     }
1980                 } else {
1981                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p));
1982                     if elts.len() == 1 {
1983                         self.s.word(",");
1984                     }
1985                 }
1986                 self.pclose();
1987             }
1988             PatKind::Box(ref inner) => {
1989                 let is_range_inner = matches!(inner.kind, PatKind::Range(..));
1990                 self.s.word("box ");
1991                 if is_range_inner {
1992                     self.popen();
1993                 }
1994                 self.print_pat(&inner);
1995                 if is_range_inner {
1996                     self.pclose();
1997                 }
1998             }
1999             PatKind::Ref(ref inner, mutbl) => {
2000                 let is_range_inner = matches!(inner.kind, PatKind::Range(..));
2001                 self.s.word("&");
2002                 self.s.word(mutbl.prefix_str());
2003                 if is_range_inner {
2004                     self.popen();
2005                 }
2006                 self.print_pat(&inner);
2007                 if is_range_inner {
2008                     self.pclose();
2009                 }
2010             }
2011             PatKind::Lit(ref e) => self.print_expr(&e),
2012             PatKind::Range(ref begin, ref end, ref end_kind) => {
2013                 if let Some(expr) = begin {
2014                     self.print_expr(expr);
2015                     self.s.space();
2016                 }
2017                 match *end_kind {
2018                     RangeEnd::Included => self.s.word("..."),
2019                     RangeEnd::Excluded => self.s.word(".."),
2020                 }
2021                 if let Some(expr) = end {
2022                     self.print_expr(expr);
2023                 }
2024             }
2025             PatKind::Slice(ref before, ref slice, ref after) => {
2026                 self.s.word("[");
2027                 self.commasep(Inconsistent, &before[..], |s, p| s.print_pat(&p));
2028                 if let Some(ref p) = *slice {
2029                     if !before.is_empty() {
2030                         self.word_space(",");
2031                     }
2032                     if let PatKind::Wild = p.kind {
2033                         // Print nothing.
2034                     } else {
2035                         self.print_pat(&p);
2036                     }
2037                     self.s.word("..");
2038                     if !after.is_empty() {
2039                         self.word_space(",");
2040                     }
2041                 }
2042                 self.commasep(Inconsistent, &after[..], |s, p| s.print_pat(&p));
2043                 self.s.word("]");
2044             }
2045         }
2046         self.ann.post(self, AnnNode::Pat(pat))
2047     }
2048
2049     pub fn print_param(&mut self, arg: &hir::Param<'_>) {
2050         self.print_outer_attributes(self.attrs(arg.hir_id));
2051         self.print_pat(&arg.pat);
2052     }
2053
2054     pub fn print_arm(&mut self, arm: &hir::Arm<'_>) {
2055         // I have no idea why this check is necessary, but here it
2056         // is :(
2057         if self.attrs(arm.hir_id).is_empty() {
2058             self.s.space();
2059         }
2060         self.cbox(INDENT_UNIT);
2061         self.ann.pre(self, AnnNode::Arm(arm));
2062         self.ibox(0);
2063         self.print_outer_attributes(&self.attrs(arm.hir_id));
2064         self.print_pat(&arm.pat);
2065         self.s.space();
2066         if let Some(ref g) = arm.guard {
2067             match g {
2068                 hir::Guard::If(e) => {
2069                     self.word_space("if");
2070                     self.print_expr(&e);
2071                     self.s.space();
2072                 }
2073                 hir::Guard::IfLet(pat, e) => {
2074                     self.word_nbsp("if");
2075                     self.word_nbsp("let");
2076                     self.print_pat(&pat);
2077                     self.s.space();
2078                     self.word_space("=");
2079                     self.print_expr(&e);
2080                     self.s.space();
2081                 }
2082             }
2083         }
2084         self.word_space("=>");
2085
2086         match arm.body.kind {
2087             hir::ExprKind::Block(ref blk, opt_label) => {
2088                 if let Some(label) = opt_label {
2089                     self.print_ident(label.ident);
2090                     self.word_space(":");
2091                 }
2092                 // the block will close the pattern's ibox
2093                 self.print_block_unclosed(&blk);
2094
2095                 // If it is a user-provided unsafe block, print a comma after it
2096                 if let hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::UserProvided) = blk.rules
2097                 {
2098                     self.s.word(",");
2099                 }
2100             }
2101             _ => {
2102                 self.end(); // close the ibox for the pattern
2103                 self.print_expr(&arm.body);
2104                 self.s.word(",");
2105             }
2106         }
2107         self.ann.post(self, AnnNode::Arm(arm));
2108         self.end() // close enclosing cbox
2109     }
2110
2111     pub fn print_fn(
2112         &mut self,
2113         decl: &hir::FnDecl<'_>,
2114         header: hir::FnHeader,
2115         name: Option<Symbol>,
2116         generics: &hir::Generics<'_>,
2117         vis: &hir::Visibility<'_>,
2118         arg_names: &[Ident],
2119         body_id: Option<hir::BodyId>,
2120     ) {
2121         self.print_fn_header_info(header, vis);
2122
2123         if let Some(name) = name {
2124             self.nbsp();
2125             self.print_name(name);
2126         }
2127         self.print_generic_params(&generics.params);
2128
2129         self.popen();
2130         let mut i = 0;
2131         // Make sure we aren't supplied *both* `arg_names` and `body_id`.
2132         assert!(arg_names.is_empty() || body_id.is_none());
2133         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
2134             s.ibox(INDENT_UNIT);
2135             if let Some(arg_name) = arg_names.get(i) {
2136                 s.s.word(arg_name.to_string());
2137                 s.s.word(":");
2138                 s.s.space();
2139             } else if let Some(body_id) = body_id {
2140                 s.ann.nested(s, Nested::BodyParamPat(body_id, i));
2141                 s.s.word(":");
2142                 s.s.space();
2143             }
2144             i += 1;
2145             s.print_type(ty);
2146             s.end()
2147         });
2148         if decl.c_variadic {
2149             self.s.word(", ...");
2150         }
2151         self.pclose();
2152
2153         self.print_fn_output(decl);
2154         self.print_where_clause(&generics.where_clause)
2155     }
2156
2157     fn print_closure_params(&mut self, decl: &hir::FnDecl<'_>, body_id: hir::BodyId) {
2158         self.s.word("|");
2159         let mut i = 0;
2160         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
2161             s.ibox(INDENT_UNIT);
2162
2163             s.ann.nested(s, Nested::BodyParamPat(body_id, i));
2164             i += 1;
2165
2166             if let hir::TyKind::Infer = ty.kind {
2167                 // Print nothing.
2168             } else {
2169                 s.s.word(":");
2170                 s.s.space();
2171                 s.print_type(ty);
2172             }
2173             s.end();
2174         });
2175         self.s.word("|");
2176
2177         if let hir::FnRetTy::DefaultReturn(..) = decl.output {
2178             return;
2179         }
2180
2181         self.space_if_not_bol();
2182         self.word_space("->");
2183         match decl.output {
2184             hir::FnRetTy::Return(ref ty) => {
2185                 self.print_type(&ty);
2186                 self.maybe_print_comment(ty.span.lo())
2187             }
2188             hir::FnRetTy::DefaultReturn(..) => unreachable!(),
2189         }
2190     }
2191
2192     pub fn print_capture_clause(&mut self, capture_clause: hir::CaptureBy) {
2193         match capture_clause {
2194             hir::CaptureBy::Value => self.word_space("move"),
2195             hir::CaptureBy::Ref => {}
2196         }
2197     }
2198
2199     pub fn print_bounds<'b>(
2200         &mut self,
2201         prefix: &'static str,
2202         bounds: impl IntoIterator<Item = &'b hir::GenericBound<'b>>,
2203     ) {
2204         let mut first = true;
2205         for bound in bounds {
2206             if first {
2207                 self.s.word(prefix);
2208             }
2209             if !(first && prefix.is_empty()) {
2210                 self.nbsp();
2211             }
2212             if first {
2213                 first = false;
2214             } else {
2215                 self.word_space("+");
2216             }
2217
2218             match bound {
2219                 GenericBound::Trait(tref, modifier) => {
2220                     if modifier == &TraitBoundModifier::Maybe {
2221                         self.s.word("?");
2222                     }
2223                     self.print_poly_trait_ref(tref);
2224                 }
2225                 GenericBound::LangItemTrait(lang_item, span, ..) => {
2226                     self.s.word("#[lang = \"");
2227                     self.print_ident(Ident::new(lang_item.name(), *span));
2228                     self.s.word("\"]");
2229                 }
2230                 GenericBound::Outlives(lt) => {
2231                     self.print_lifetime(lt);
2232                 }
2233             }
2234         }
2235     }
2236
2237     pub fn print_generic_params(&mut self, generic_params: &[GenericParam<'_>]) {
2238         if !generic_params.is_empty() {
2239             self.s.word("<");
2240
2241             self.commasep(Inconsistent, generic_params, |s, param| s.print_generic_param(param));
2242
2243             self.s.word(">");
2244         }
2245     }
2246
2247     pub fn print_generic_param(&mut self, param: &GenericParam<'_>) {
2248         if let GenericParamKind::Const { .. } = param.kind {
2249             self.word_space("const");
2250         }
2251
2252         self.print_ident(param.name.ident());
2253
2254         match param.kind {
2255             GenericParamKind::Lifetime { .. } => {
2256                 let mut sep = ":";
2257                 for bound in param.bounds {
2258                     match bound {
2259                         GenericBound::Outlives(ref lt) => {
2260                             self.s.word(sep);
2261                             self.print_lifetime(lt);
2262                             sep = "+";
2263                         }
2264                         _ => panic!(),
2265                     }
2266                 }
2267             }
2268             GenericParamKind::Type { ref default, .. } => {
2269                 self.print_bounds(":", param.bounds);
2270                 if let Some(default) = default {
2271                     self.s.space();
2272                     self.word_space("=");
2273                     self.print_type(&default)
2274                 }
2275             }
2276             GenericParamKind::Const { ref ty, ref default } => {
2277                 self.word_space(":");
2278                 self.print_type(ty);
2279                 if let Some(ref default) = default {
2280                     self.s.space();
2281                     self.word_space("=");
2282                     self.print_anon_const(&default)
2283                 }
2284             }
2285         }
2286     }
2287
2288     pub fn print_lifetime(&mut self, lifetime: &hir::Lifetime) {
2289         self.print_ident(lifetime.name.ident())
2290     }
2291
2292     pub fn print_where_clause(&mut self, where_clause: &hir::WhereClause<'_>) {
2293         if where_clause.predicates.is_empty() {
2294             return;
2295         }
2296
2297         self.s.space();
2298         self.word_space("where");
2299
2300         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2301             if i != 0 {
2302                 self.word_space(",");
2303             }
2304
2305             match predicate {
2306                 hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
2307                     bound_generic_params,
2308                     bounded_ty,
2309                     bounds,
2310                     ..
2311                 }) => {
2312                     self.print_formal_generic_params(bound_generic_params);
2313                     self.print_type(&bounded_ty);
2314                     self.print_bounds(":", *bounds);
2315                 }
2316                 hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
2317                     lifetime,
2318                     bounds,
2319                     ..
2320                 }) => {
2321                     self.print_lifetime(lifetime);
2322                     self.s.word(":");
2323
2324                     for (i, bound) in bounds.iter().enumerate() {
2325                         match bound {
2326                             GenericBound::Outlives(lt) => {
2327                                 self.print_lifetime(lt);
2328                             }
2329                             _ => panic!(),
2330                         }
2331
2332                         if i != 0 {
2333                             self.s.word(":");
2334                         }
2335                     }
2336                 }
2337                 hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
2338                     lhs_ty, rhs_ty, ..
2339                 }) => {
2340                     self.print_type(lhs_ty);
2341                     self.s.space();
2342                     self.word_space("=");
2343                     self.print_type(rhs_ty);
2344                 }
2345             }
2346         }
2347     }
2348
2349     pub fn print_mutability(&mut self, mutbl: hir::Mutability, print_const: bool) {
2350         match mutbl {
2351             hir::Mutability::Mut => self.word_nbsp("mut"),
2352             hir::Mutability::Not => {
2353                 if print_const {
2354                     self.word_nbsp("const")
2355                 }
2356             }
2357         }
2358     }
2359
2360     pub fn print_mt(&mut self, mt: &hir::MutTy<'_>, print_const: bool) {
2361         self.print_mutability(mt.mutbl, print_const);
2362         self.print_type(&mt.ty)
2363     }
2364
2365     pub fn print_fn_output(&mut self, decl: &hir::FnDecl<'_>) {
2366         if let hir::FnRetTy::DefaultReturn(..) = decl.output {
2367             return;
2368         }
2369
2370         self.space_if_not_bol();
2371         self.ibox(INDENT_UNIT);
2372         self.word_space("->");
2373         match decl.output {
2374             hir::FnRetTy::DefaultReturn(..) => unreachable!(),
2375             hir::FnRetTy::Return(ref ty) => self.print_type(&ty),
2376         }
2377         self.end();
2378
2379         if let hir::FnRetTy::Return(ref output) = decl.output {
2380             self.maybe_print_comment(output.span.lo())
2381         }
2382     }
2383
2384     pub fn print_ty_fn(
2385         &mut self,
2386         abi: Abi,
2387         unsafety: hir::Unsafety,
2388         decl: &hir::FnDecl<'_>,
2389         name: Option<Symbol>,
2390         generic_params: &[hir::GenericParam<'_>],
2391         arg_names: &[Ident],
2392     ) {
2393         self.ibox(INDENT_UNIT);
2394         if !generic_params.is_empty() {
2395             self.s.word("for");
2396             self.print_generic_params(generic_params);
2397         }
2398         let generics = hir::Generics {
2399             params: &[],
2400             where_clause: hir::WhereClause { predicates: &[], span: rustc_span::DUMMY_SP },
2401             span: rustc_span::DUMMY_SP,
2402         };
2403         self.print_fn(
2404             decl,
2405             hir::FnHeader {
2406                 unsafety,
2407                 abi,
2408                 constness: hir::Constness::NotConst,
2409                 asyncness: hir::IsAsync::NotAsync,
2410             },
2411             name,
2412             &generics,
2413             &Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited },
2414             arg_names,
2415             None,
2416         );
2417         self.end();
2418     }
2419
2420     pub fn maybe_print_trailing_comment(
2421         &mut self,
2422         span: rustc_span::Span,
2423         next_pos: Option<BytePos>,
2424     ) {
2425         if let Some(cmnts) = self.comments() {
2426             if let Some(cmnt) = cmnts.trailing_comment(span, next_pos) {
2427                 self.print_comment(&cmnt);
2428             }
2429         }
2430     }
2431
2432     pub fn print_remaining_comments(&mut self) {
2433         // If there aren't any remaining comments, then we need to manually
2434         // make sure there is a line break at the end.
2435         if self.next_comment().is_none() {
2436             self.s.hardbreak();
2437         }
2438         while let Some(ref cmnt) = self.next_comment() {
2439             self.print_comment(cmnt)
2440         }
2441     }
2442
2443     pub fn print_fn_header_info(&mut self, header: hir::FnHeader, vis: &hir::Visibility<'_>) {
2444         self.s.word(visibility_qualified(vis, ""));
2445
2446         match header.constness {
2447             hir::Constness::NotConst => {}
2448             hir::Constness::Const => self.word_nbsp("const"),
2449         }
2450
2451         match header.asyncness {
2452             hir::IsAsync::NotAsync => {}
2453             hir::IsAsync::Async => self.word_nbsp("async"),
2454         }
2455
2456         self.print_unsafety(header.unsafety);
2457
2458         if header.abi != Abi::Rust {
2459             self.word_nbsp("extern");
2460             self.word_nbsp(header.abi.to_string());
2461         }
2462
2463         self.s.word("fn")
2464     }
2465
2466     pub fn print_unsafety(&mut self, s: hir::Unsafety) {
2467         match s {
2468             hir::Unsafety::Normal => {}
2469             hir::Unsafety::Unsafe => self.word_nbsp("unsafe"),
2470         }
2471     }
2472
2473     pub fn print_is_auto(&mut self, s: hir::IsAuto) {
2474         match s {
2475             hir::IsAuto::Yes => self.word_nbsp("auto"),
2476             hir::IsAuto::No => {}
2477         }
2478     }
2479 }
2480
2481 /// Does this expression require a semicolon to be treated
2482 /// as a statement? The negation of this: 'can this expression
2483 /// be used as a statement without a semicolon' -- is used
2484 /// as an early-bail-out in the parser so that, for instance,
2485 ///     if true {...} else {...}
2486 ///      |x| 5
2487 /// isn't parsed as (if true {...} else {...} | x) | 5
2488 //
2489 // Duplicated from `parse::classify`, but adapted for the HIR.
2490 fn expr_requires_semi_to_be_stmt(e: &hir::Expr<'_>) -> bool {
2491     !matches!(
2492         e.kind,
2493         hir::ExprKind::If(..)
2494             | hir::ExprKind::Match(..)
2495             | hir::ExprKind::Block(..)
2496             | hir::ExprKind::Loop(..)
2497     )
2498 }
2499
2500 /// This statement requires a semicolon after it.
2501 /// note that in one case (stmt_semi), we've already
2502 /// seen the semicolon, and thus don't need another.
2503 fn stmt_ends_with_semi(stmt: &hir::StmtKind<'_>) -> bool {
2504     match *stmt {
2505         hir::StmtKind::Local(_) => true,
2506         hir::StmtKind::Item(_) => false,
2507         hir::StmtKind::Expr(ref e) => expr_requires_semi_to_be_stmt(&e),
2508         hir::StmtKind::Semi(..) => false,
2509     }
2510 }
2511
2512 fn bin_op_to_assoc_op(op: hir::BinOpKind) -> AssocOp {
2513     use crate::hir::BinOpKind::*;
2514     match op {
2515         Add => AssocOp::Add,
2516         Sub => AssocOp::Subtract,
2517         Mul => AssocOp::Multiply,
2518         Div => AssocOp::Divide,
2519         Rem => AssocOp::Modulus,
2520
2521         And => AssocOp::LAnd,
2522         Or => AssocOp::LOr,
2523
2524         BitXor => AssocOp::BitXor,
2525         BitAnd => AssocOp::BitAnd,
2526         BitOr => AssocOp::BitOr,
2527         Shl => AssocOp::ShiftLeft,
2528         Shr => AssocOp::ShiftRight,
2529
2530         Eq => AssocOp::Equal,
2531         Lt => AssocOp::Less,
2532         Le => AssocOp::LessEqual,
2533         Ne => AssocOp::NotEqual,
2534         Ge => AssocOp::GreaterEqual,
2535         Gt => AssocOp::Greater,
2536     }
2537 }
2538
2539 /// Expressions that syntactically contain an "exterior" struct literal, i.e., not surrounded by any
2540 /// parens or other delimiters, e.g., `X { y: 1 }`, `X { y: 1 }.method()`, `foo == X { y: 1 }` and
2541 /// `X { y: 1 } == foo` all do, but `(X { y: 1 }) == foo` does not.
2542 fn contains_exterior_struct_lit(value: &hir::Expr<'_>) -> bool {
2543     match value.kind {
2544         hir::ExprKind::Struct(..) => true,
2545
2546         hir::ExprKind::Assign(ref lhs, ref rhs, _)
2547         | hir::ExprKind::AssignOp(_, ref lhs, ref rhs)
2548         | hir::ExprKind::Binary(_, ref lhs, ref rhs) => {
2549             // `X { y: 1 } + X { y: 2 }`
2550             contains_exterior_struct_lit(&lhs) || contains_exterior_struct_lit(&rhs)
2551         }
2552         hir::ExprKind::Unary(_, ref x)
2553         | hir::ExprKind::Cast(ref x, _)
2554         | hir::ExprKind::Type(ref x, _)
2555         | hir::ExprKind::Field(ref x, _)
2556         | hir::ExprKind::Index(ref x, _) => {
2557             // `&X { y: 1 }, X { y: 1 }.y`
2558             contains_exterior_struct_lit(&x)
2559         }
2560
2561         hir::ExprKind::MethodCall(.., ref exprs, _) => {
2562             // `X { y: 1 }.bar(...)`
2563             contains_exterior_struct_lit(&exprs[0])
2564         }
2565
2566         _ => false,
2567     }
2568 }