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