compiler/rustc_ast_pretty/src/pprust/state.rs

   1 use crate::pp::Breaks::{Consistent, Inconsistent};
   2 use crate::pp::{self, Breaks};
   3
   4 use rustc_ast::attr;
   5 use rustc_ast::ptr::P;
   6 use rustc_ast::token::{self, BinOpToken, CommentKind, DelimToken, Nonterminal, Token, TokenKind};
   7 use rustc_ast::tokenstream::{TokenStream, TokenTree};
   8 use rustc_ast::util::classify;
   9 use rustc_ast::util::comments::{gather_comments, Comment, CommentStyle};
  10 use rustc_ast::util::parser::{self, AssocOp, Fixity};
  11 use rustc_ast::{self as ast, BlockCheckMode, PatKind, RangeEnd, RangeSyntax};
  12 use rustc_ast::{GenericArg, MacArgs, ModKind};
  13 use rustc_ast::{GenericBound, SelfKind, TraitBoundModifier};
  14 use rustc_ast::{InlineAsmOperand, InlineAsmRegOrRegClass};
  15 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
  16 use rustc_span::edition::Edition;
  17 use rustc_span::source_map::{SourceMap, Spanned};
  18 use rustc_span::symbol::{kw, sym, Ident, IdentPrinter, Symbol};
  19 use rustc_span::{BytePos, FileName, Span};
  20
  21 use std::borrow::Cow;
  22
  23 pub enum MacHeader<'a> {
  24     Path(&'a ast::Path),
  25     Keyword(&'static str),
  26 }
  27
  28 pub enum AnnNode<'a> {
  29     Ident(&'a Ident),
  30     Name(&'a Symbol),
  31     Block(&'a ast::Block),
  32     Item(&'a ast::Item),
  33     SubItem(ast::NodeId),
  34     Expr(&'a ast::Expr),
  35     Pat(&'a ast::Pat),
  36     Crate(&'a ast::Crate),
  37 }
  38
  39 pub trait PpAnn {
  40     fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
  41     fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
  42 }
  43
  44 #[derive(Copy, Clone)]
  45 pub struct NoAnn;
  46
  47 impl PpAnn for NoAnn {}
  48
  49 pub struct Comments<'a> {
  50     sm: &'a SourceMap,
  51     comments: Vec<Comment>,
  52     current: usize,
  53 }
  54
  55 impl<'a> Comments<'a> {
  56     pub fn new(sm: &'a SourceMap, filename: FileName, input: String) -> Comments<'a> {
  57         let comments = gather_comments(sm, filename, input);
  58         Comments { sm, comments, current: 0 }
  59     }
  60
  61     pub fn next(&self) -> Option<Comment> {
  62         self.comments.get(self.current).cloned()
  63     }
  64
  65     pub fn trailing_comment(
  66         &self,
  67         span: rustc_span::Span,
  68         next_pos: Option<BytePos>,
  69     ) -> Option<Comment> {
  70         if let Some(cmnt) = self.next() {
  71             if cmnt.style != CommentStyle::Trailing {
  72                 return None;
  73             }
  74             let span_line = self.sm.lookup_char_pos(span.hi());
  75             let comment_line = self.sm.lookup_char_pos(cmnt.pos);
  76             let next = next_pos.unwrap_or_else(|| cmnt.pos + BytePos(1));
  77             if span.hi() < cmnt.pos && cmnt.pos < next && span_line.line == comment_line.line {
  78                 return Some(cmnt);
  79             }
  80         }
  81
  82         None
  83     }
  84 }
  85
  86 pub struct State<'a> {
  87     pub s: pp::Printer,
  88     comments: Option<Comments<'a>>,
  89     ann: &'a (dyn PpAnn + 'a),
  90 }
  91
  92 crate const INDENT_UNIT: usize = 4;
  93
  94 /// Requires you to pass an input filename and reader so that
  95 /// it can scan the input text for comments to copy forward.
  96 pub fn print_crate<'a>(
  97     sm: &'a SourceMap,
  98     krate: &ast::Crate,
  99     filename: FileName,
 100     input: String,
 101     ann: &'a dyn PpAnn,
 102     is_expanded: bool,
 103     edition: Edition,
 104 ) -> String {
 105     let mut s =
 106         State { s: pp::mk_printer(), comments: Some(Comments::new(sm, filename, input)), ann };
 107
 108     if is_expanded && !krate.attrs.iter().any(|attr| attr.has_name(sym::no_core)) {
 109         // We need to print `#![no_std]` (and its feature gate) so that
 110         // compiling pretty-printed source won't inject libstd again.
 111         // However, we don't want these attributes in the AST because
 112         // of the feature gate, so we fake them up here.
 113
 114         // `#![feature(prelude_import)]`
 115         let pi_nested = attr::mk_nested_word_item(Ident::with_dummy_span(sym::prelude_import));
 116         let list = attr::mk_list_item(Ident::with_dummy_span(sym::feature), vec![pi_nested]);
 117         let fake_attr = attr::mk_attr_inner(list);
 118         s.print_attribute(&fake_attr);
 119
 120         // Currently, in Rust 2018 we don't have `extern crate std;` at the crate
 121         // root, so this is not needed, and actually breaks things.
 122         if edition == Edition::Edition2015 {
 123             // `#![no_std]`
 124             let no_std_meta = attr::mk_word_item(Ident::with_dummy_span(sym::no_std));
 125             let fake_attr = attr::mk_attr_inner(no_std_meta);
 126             s.print_attribute(&fake_attr);
 127         }
 128     }
 129
 130     s.print_inner_attributes(&krate.attrs);
 131     for item in &krate.items {
 132         s.print_item(item);
 133     }
 134     s.print_remaining_comments();
 135     s.ann.post(&mut s, AnnNode::Crate(krate));
 136     s.s.eof()
 137 }
 138
 139 // This makes printed token streams look slightly nicer,
 140 // and also addresses some specific regressions described in #63896 and #73345.
 141 fn tt_prepend_space(tt: &TokenTree, prev: &TokenTree) -> bool {
 142     if let TokenTree::Token(token) = prev {
 143         if let token::DocComment(comment_kind, ..) = token.kind {
 144             return comment_kind != CommentKind::Line;
 145         }
 146     }
 147     match tt {
 148         TokenTree::Token(token) => token.kind != token::Comma,
 149         TokenTree::Delimited(_, DelimToken::Paren, _) => {
 150             !matches!(prev, TokenTree::Token(Token { kind: token::Ident(..), .. }))
 151         }
 152         TokenTree::Delimited(_, DelimToken::Bracket, _) => {
 153             !matches!(prev, TokenTree::Token(Token { kind: token::Pound, .. }))
 154         }
 155         TokenTree::Delimited(..) => true,
 156     }
 157 }
 158
 159 fn binop_to_string(op: BinOpToken) -> &'static str {
 160     match op {
 161         token::Plus => "+",
 162         token::Minus => "-",
 163         token::Star => "*",
 164         token::Slash => "/",
 165         token::Percent => "%",
 166         token::Caret => "^",
 167         token::And => "&",
 168         token::Or => "|",
 169         token::Shl => "<<",
 170         token::Shr => ">>",
 171     }
 172 }
 173
 174 fn doc_comment_to_string(
 175     comment_kind: CommentKind,
 176     attr_style: ast::AttrStyle,
 177     data: Symbol,
 178 ) -> String {
 179     match (comment_kind, attr_style) {
 180         (CommentKind::Line, ast::AttrStyle::Outer) => format!("///{}", data),
 181         (CommentKind::Line, ast::AttrStyle::Inner) => format!("//!{}", data),
 182         (CommentKind::Block, ast::AttrStyle::Outer) => format!("/**{}*/", data),
 183         (CommentKind::Block, ast::AttrStyle::Inner) => format!("/*!{}*/", data),
 184     }
 185 }
 186
 187 pub fn literal_to_string(lit: token::Lit) -> String {
 188     let token::Lit { kind, symbol, suffix } = lit;
 189     let mut out = match kind {
 190         token::Byte => format!("b'{}'", symbol),
 191         token::Char => format!("'{}'", symbol),
 192         token::Str => format!("\"{}\"", symbol),
 193         token::StrRaw(n) => {
 194             format!("r{delim}\"{string}\"{delim}", delim = "#".repeat(n as usize), string = symbol)
 195         }
 196         token::ByteStr => format!("b\"{}\"", symbol),
 197         token::ByteStrRaw(n) => {
 198             format!("br{delim}\"{string}\"{delim}", delim = "#".repeat(n as usize), string = symbol)
 199         }
 200         token::Integer | token::Float | token::Bool | token::Err => symbol.to_string(),
 201     };
 202
 203     if let Some(suffix) = suffix {
 204         out.push_str(&suffix.as_str())
 205     }
 206
 207     out
 208 }
 209
 210 fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
 211     format!("{}{}", State::new().to_string(|s| s.print_visibility(vis)), s)
 212 }
 213
 214 impl std::ops::Deref for State<'_> {
 215     type Target = pp::Printer;
 216     fn deref(&self) -> &Self::Target {
 217         &self.s
 218     }
 219 }
 220
 221 impl std::ops::DerefMut for State<'_> {
 222     fn deref_mut(&mut self) -> &mut Self::Target {
 223         &mut self.s
 224     }
 225 }
 226
 227 pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::DerefMut {
 228     fn comments(&mut self) -> &mut Option<Comments<'a>>;
 229     fn print_ident(&mut self, ident: Ident);
 230     fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool);
 231
 232     fn strsep<T, F>(
 233         &mut self,
 234         sep: &'static str,
 235         space_before: bool,
 236         b: Breaks,
 237         elts: &[T],
 238         mut op: F,
 239     ) where
 240         F: FnMut(&mut Self, &T),
 241     {
 242         self.rbox(0, b);
 243         if let Some((first, rest)) = elts.split_first() {
 244             op(self, first);
 245             for elt in rest {
 246                 if space_before {
 247                     self.space();
 248                 }
 249                 self.word_space(sep);
 250                 op(self, elt);
 251             }
 252         }
 253         self.end();
 254     }
 255
 256     fn commasep<T, F>(&mut self, b: Breaks, elts: &[T], op: F)
 257     where
 258         F: FnMut(&mut Self, &T),
 259     {
 260         self.strsep(",", false, b, elts, op)
 261     }
 262
 263     fn maybe_print_comment(&mut self, pos: BytePos) {
 264         while let Some(ref cmnt) = self.next_comment() {
 265             if cmnt.pos < pos {
 266                 self.print_comment(cmnt);
 267             } else {
 268                 break;
 269             }
 270         }
 271     }
 272
 273     fn print_comment(&mut self, cmnt: &Comment) {
 274         match cmnt.style {
 275             CommentStyle::Mixed => {
 276                 if !self.is_beginning_of_line() {
 277                     self.zerobreak();
 278                 }
 279                 if let Some((last, lines)) = cmnt.lines.split_last() {
 280                     self.ibox(0);
 281
 282                     for line in lines {
 283                         self.word(line.clone());
 284                         self.hardbreak()
 285                     }
 286
 287                     self.word(last.clone());
 288                     self.space();
 289
 290                     self.end();
 291                 }
 292                 self.zerobreak()
 293             }
 294             CommentStyle::Isolated => {
 295                 self.hardbreak_if_not_bol();
 296                 for line in &cmnt.lines {
 297                     // Don't print empty lines because they will end up as trailing
 298                     // whitespace.
 299                     if !line.is_empty() {
 300                         self.word(line.clone());
 301                     }
 302                     self.hardbreak();
 303                 }
 304             }
 305             CommentStyle::Trailing => {
 306                 if !self.is_beginning_of_line() {
 307                     self.word(" ");
 308                 }
 309                 if cmnt.lines.len() == 1 {
 310                     self.word(cmnt.lines[0].clone());
 311                     self.hardbreak()
 312                 } else {
 313                     self.ibox(0);
 314                     for line in &cmnt.lines {
 315                         if !line.is_empty() {
 316                             self.word(line.clone());
 317                         }
 318                         self.hardbreak();
 319                     }
 320                     self.end();
 321                 }
 322             }
 323             CommentStyle::BlankLine => {
 324                 // We need to do at least one, possibly two hardbreaks.
 325                 let twice = match self.last_token() {
 326                     pp::Token::String(s) => ";" == s,
 327                     pp::Token::Begin(_) => true,
 328                     pp::Token::End => true,
 329                     _ => false,
 330                 };
 331                 if twice {
 332                     self.hardbreak();
 333                 }
 334                 self.hardbreak();
 335             }
 336         }
 337         if let Some(cmnts) = self.comments() {
 338             cmnts.current += 1;
 339         }
 340     }
 341
 342     fn next_comment(&mut self) -> Option<Comment> {
 343         self.comments().as_mut().and_then(|c| c.next())
 344     }
 345
 346     fn print_literal(&mut self, lit: &ast::Lit) {
 347         self.maybe_print_comment(lit.span.lo());
 348         self.word(lit.token.to_string())
 349     }
 350
 351     fn print_string(&mut self, st: &str, style: ast::StrStyle) {
 352         let st = match style {
 353             ast::StrStyle::Cooked => (format!("\"{}\"", st.escape_debug())),
 354             ast::StrStyle::Raw(n) => {
 355                 format!("r{delim}\"{string}\"{delim}", delim = "#".repeat(n as usize), string = st)
 356             }
 357         };
 358         self.word(st)
 359     }
 360
 361     fn print_symbol(&mut self, sym: Symbol, style: ast::StrStyle) {
 362         self.print_string(&sym.as_str(), style);
 363     }
 364
 365     fn print_inner_attributes(&mut self, attrs: &[ast::Attribute]) {
 366         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
 367     }
 368
 369     fn print_inner_attributes_no_trailing_hardbreak(&mut self, attrs: &[ast::Attribute]) {
 370         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
 371     }
 372
 373     fn print_outer_attributes(&mut self, attrs: &[ast::Attribute]) {
 374         self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
 375     }
 376
 377     fn print_inner_attributes_inline(&mut self, attrs: &[ast::Attribute]) {
 378         self.print_either_attributes(attrs, ast::AttrStyle::Inner, true, true)
 379     }
 380
 381     fn print_outer_attributes_inline(&mut self, attrs: &[ast::Attribute]) {
 382         self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
 383     }
 384
 385     fn print_either_attributes(
 386         &mut self,
 387         attrs: &[ast::Attribute],
 388         kind: ast::AttrStyle,
 389         is_inline: bool,
 390         trailing_hardbreak: bool,
 391     ) {
 392         let mut count = 0;
 393         for attr in attrs {
 394             if attr.style == kind {
 395                 self.print_attribute_inline(attr, is_inline);
 396                 if is_inline {
 397                     self.nbsp();
 398                 }
 399                 count += 1;
 400             }
 401         }
 402         if count > 0 && trailing_hardbreak && !is_inline {
 403             self.hardbreak_if_not_bol();
 404         }
 405     }
 406
 407     fn print_attribute(&mut self, attr: &ast::Attribute) {
 408         self.print_attribute_inline(attr, false)
 409     }
 410
 411     fn print_attribute_inline(&mut self, attr: &ast::Attribute, is_inline: bool) {
 412         if !is_inline {
 413             self.hardbreak_if_not_bol();
 414         }
 415         self.maybe_print_comment(attr.span.lo());
 416         match attr.kind {
 417             ast::AttrKind::Normal(ref item, _) => {
 418                 match attr.style {
 419                     ast::AttrStyle::Inner => self.word("#!["),
 420                     ast::AttrStyle::Outer => self.word("#["),
 421                 }
 422                 self.print_attr_item(&item, attr.span);
 423                 self.word("]");
 424             }
 425             ast::AttrKind::DocComment(comment_kind, data) => {
 426                 self.word(doc_comment_to_string(comment_kind, attr.style, data));
 427                 self.hardbreak()
 428             }
 429         }
 430     }
 431
 432     fn print_attr_item(&mut self, item: &ast::AttrItem, span: Span) {
 433         self.ibox(0);
 434         match &item.args {
 435             MacArgs::Delimited(_, delim, tokens) => self.print_mac_common(
 436                 Some(MacHeader::Path(&item.path)),
 437                 false,
 438                 None,
 439                 delim.to_token(),
 440                 tokens,
 441                 true,
 442                 span,
 443             ),
 444             MacArgs::Empty | MacArgs::Eq(..) => {
 445                 self.print_path(&item.path, false, 0);
 446                 if let MacArgs::Eq(_, token) = &item.args {
 447                     self.space();
 448                     self.word_space("=");
 449                     let token_str = self.token_to_string_ext(token, true);
 450                     self.word(token_str);
 451                 }
 452             }
 453         }
 454         self.end();
 455     }
 456
 457     fn print_meta_list_item(&mut self, item: &ast::NestedMetaItem) {
 458         match item {
 459             ast::NestedMetaItem::MetaItem(ref mi) => self.print_meta_item(mi),
 460             ast::NestedMetaItem::Literal(ref lit) => self.print_literal(lit),
 461         }
 462     }
 463
 464     fn print_meta_item(&mut self, item: &ast::MetaItem) {
 465         self.ibox(INDENT_UNIT);
 466         match item.kind {
 467             ast::MetaItemKind::Word => self.print_path(&item.path, false, 0),
 468             ast::MetaItemKind::NameValue(ref value) => {
 469                 self.print_path(&item.path, false, 0);
 470                 self.space();
 471                 self.word_space("=");
 472                 self.print_literal(value);
 473             }
 474             ast::MetaItemKind::List(ref items) => {
 475                 self.print_path(&item.path, false, 0);
 476                 self.popen();
 477                 self.commasep(Consistent, &items[..], |s, i| s.print_meta_list_item(i));
 478                 self.pclose();
 479             }
 480         }
 481         self.end();
 482     }
 483
 484     /// This doesn't deserve to be called "pretty" printing, but it should be
 485     /// meaning-preserving. A quick hack that might help would be to look at the
 486     /// spans embedded in the TTs to decide where to put spaces and newlines.
 487     /// But it'd be better to parse these according to the grammar of the
 488     /// appropriate macro, transcribe back into the grammar we just parsed from,
 489     /// and then pretty-print the resulting AST nodes (so, e.g., we print
 490     /// expression arguments as expressions). It can be done! I think.
 491     fn print_tt(&mut self, tt: &TokenTree, convert_dollar_crate: bool) {
 492         match tt {
 493             TokenTree::Token(token) => {
 494                 let token_str = self.token_to_string_ext(&token, convert_dollar_crate);
 495                 self.word(token_str);
 496                 if let token::DocComment(..) = token.kind {
 497                     self.hardbreak()
 498                 }
 499             }
 500             TokenTree::Delimited(dspan, delim, tts) => {
 501                 self.print_mac_common(
 502                     None,
 503                     false,
 504                     None,
 505                     *delim,
 506                     tts,
 507                     convert_dollar_crate,
 508                     dspan.entire(),
 509                 );
 510             }
 511         }
 512     }
 513
 514     fn print_tts(&mut self, tts: &TokenStream, convert_dollar_crate: bool) {
 515         let mut iter = tts.trees().peekable();
 516         while let Some(tt) = iter.next() {
 517             self.print_tt(&tt, convert_dollar_crate);
 518             if let Some(next) = iter.peek() {
 519                 if tt_prepend_space(next, &tt) {
 520                     self.space();
 521                 }
 522             }
 523         }
 524     }
 525
 526     fn print_mac_common(
 527         &mut self,
 528         header: Option<MacHeader<'_>>,
 529         has_bang: bool,
 530         ident: Option<Ident>,
 531         delim: DelimToken,
 532         tts: &TokenStream,
 533         convert_dollar_crate: bool,
 534         span: Span,
 535     ) {
 536         if delim == DelimToken::Brace {
 537             self.cbox(INDENT_UNIT);
 538         }
 539         match header {
 540             Some(MacHeader::Path(path)) => self.print_path(path, false, 0),
 541             Some(MacHeader::Keyword(kw)) => self.word(kw),
 542             None => {}
 543         }
 544         if has_bang {
 545             self.word("!");
 546         }
 547         if let Some(ident) = ident {
 548             self.nbsp();
 549             self.print_ident(ident);
 550         }
 551         match delim {
 552             DelimToken::Brace => {
 553                 if header.is_some() || has_bang || ident.is_some() {
 554                     self.nbsp();
 555                 }
 556                 self.word("{");
 557                 if !tts.is_empty() {
 558                     self.space();
 559                 }
 560             }
 561             _ => {
 562                 let token_str = self.token_kind_to_string(&token::OpenDelim(delim));
 563                 self.word(token_str)
 564             }
 565         }
 566         self.ibox(0);
 567         self.print_tts(tts, convert_dollar_crate);
 568         self.end();
 569         match delim {
 570             DelimToken::Brace => self.bclose(span),
 571             _ => {
 572                 let token_str = self.token_kind_to_string(&token::CloseDelim(delim));
 573                 self.word(token_str)
 574             }
 575         }
 576     }
 577
 578     fn print_path(&mut self, path: &ast::Path, colons_before_params: bool, depth: usize) {
 579         self.maybe_print_comment(path.span.lo());
 580
 581         for (i, segment) in path.segments[..path.segments.len() - depth].iter().enumerate() {
 582             if i > 0 {
 583                 self.word("::")
 584             }
 585             self.print_path_segment(segment, colons_before_params);
 586         }
 587     }
 588
 589     fn print_path_segment(&mut self, segment: &ast::PathSegment, colons_before_params: bool) {
 590         if segment.ident.name != kw::PathRoot {
 591             self.print_ident(segment.ident);
 592             if let Some(ref args) = segment.args {
 593                 self.print_generic_args(args, colons_before_params);
 594             }
 595         }
 596     }
 597
 598     fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 599         let w = w.into();
 600         // Outer-box is consistent.
 601         self.cbox(INDENT_UNIT);
 602         // Head-box is inconsistent.
 603         self.ibox(w.len() + 1);
 604         // Keyword that starts the head.
 605         if !w.is_empty() {
 606             self.word_nbsp(w);
 607         }
 608     }
 609
 610     fn bopen(&mut self) {
 611         self.word("{");
 612         self.end(); // Close the head-box.
 613     }
 614
 615     fn bclose_maybe_open(&mut self, span: rustc_span::Span, close_box: bool) {
 616         self.maybe_print_comment(span.hi());
 617         self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
 618         self.word("}");
 619         if close_box {
 620             self.end(); // Close the outer-box.
 621         }
 622     }
 623
 624     fn bclose(&mut self, span: rustc_span::Span) {
 625         self.bclose_maybe_open(span, true)
 626     }
 627
 628     fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
 629         if !self.is_beginning_of_line() {
 630             self.break_offset(n, off)
 631         } else if off != 0 && self.last_token().is_hardbreak_tok() {
 632             // We do something pretty sketchy here: tuck the nonzero
 633             // offset-adjustment we were going to deposit along with the
 634             // break into the previous hardbreak.
 635             self.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 636         }
 637     }
 638
 639     fn nonterminal_to_string(&self, nt: &Nonterminal) -> String {
 640         match *nt {
 641             token::NtExpr(ref e) => self.expr_to_string(e),
 642             token::NtMeta(ref e) => self.attr_item_to_string(e),
 643             token::NtTy(ref e) => self.ty_to_string(e),
 644             token::NtPath(ref e) => self.path_to_string(e),
 645             token::NtItem(ref e) => self.item_to_string(e),
 646             token::NtBlock(ref e) => self.block_to_string(e),
 647             token::NtStmt(ref e) => self.stmt_to_string(e),
 648             token::NtPat(ref e) => self.pat_to_string(e),
 649             token::NtIdent(e, is_raw) => IdentPrinter::for_ast_ident(e, is_raw).to_string(),
 650             token::NtLifetime(e) => e.to_string(),
 651             token::NtLiteral(ref e) => self.expr_to_string(e),
 652             token::NtTT(ref tree) => self.tt_to_string(tree),
 653             token::NtVis(ref e) => self.vis_to_string(e),
 654         }
 655     }
 656
 657     /// Print the token kind precisely, without converting `$crate` into its respective crate name.
 658     fn token_kind_to_string(&self, tok: &TokenKind) -> String {
 659         self.token_kind_to_string_ext(tok, None)
 660     }
 661
 662     fn token_kind_to_string_ext(
 663         &self,
 664         tok: &TokenKind,
 665         convert_dollar_crate: Option<Span>,
 666     ) -> String {
 667         match *tok {
 668             token::Eq => "=".to_string(),
 669             token::Lt => "<".to_string(),
 670             token::Le => "<=".to_string(),
 671             token::EqEq => "==".to_string(),
 672             token::Ne => "!=".to_string(),
 673             token::Ge => ">=".to_string(),
 674             token::Gt => ">".to_string(),
 675             token::Not => "!".to_string(),
 676             token::Tilde => "~".to_string(),
 677             token::OrOr => "||".to_string(),
 678             token::AndAnd => "&&".to_string(),
 679             token::BinOp(op) => binop_to_string(op).to_string(),
 680             token::BinOpEq(op) => format!("{}=", binop_to_string(op)),
 681
 682             /* Structural symbols */
 683             token::At => "@".to_string(),
 684             token::Dot => ".".to_string(),
 685             token::DotDot => "..".to_string(),
 686             token::DotDotDot => "...".to_string(),
 687             token::DotDotEq => "..=".to_string(),
 688             token::Comma => ",".to_string(),
 689             token::Semi => ";".to_string(),
 690             token::Colon => ":".to_string(),
 691             token::ModSep => "::".to_string(),
 692             token::RArrow => "->".to_string(),
 693             token::LArrow => "<-".to_string(),
 694             token::FatArrow => "=>".to_string(),
 695             token::OpenDelim(token::Paren) => "(".to_string(),
 696             token::CloseDelim(token::Paren) => ")".to_string(),
 697             token::OpenDelim(token::Bracket) => "[".to_string(),
 698             token::CloseDelim(token::Bracket) => "]".to_string(),
 699             token::OpenDelim(token::Brace) => "{".to_string(),
 700             token::CloseDelim(token::Brace) => "}".to_string(),
 701             token::OpenDelim(token::NoDelim) | token::CloseDelim(token::NoDelim) => "".to_string(),
 702             token::Pound => "#".to_string(),
 703             token::Dollar => "$".to_string(),
 704             token::Question => "?".to_string(),
 705             token::SingleQuote => "'".to_string(),
 706
 707             /* Literals */
 708             token::Literal(lit) => literal_to_string(lit),
 709
 710             /* Name components */
 711             token::Ident(s, is_raw) => {
 712                 IdentPrinter::new(s, is_raw, convert_dollar_crate).to_string()
 713             }
 714             token::Lifetime(s) => s.to_string(),
 715
 716             /* Other */
 717             token::DocComment(comment_kind, attr_style, data) => {
 718                 doc_comment_to_string(comment_kind, attr_style, data)
 719             }
 720             token::Eof => "<eof>".to_string(),
 721
 722             token::Interpolated(ref nt) => self.nonterminal_to_string(nt),
 723         }
 724     }
 725
 726     /// Print the token precisely, without converting `$crate` into its respective crate name.
 727     fn token_to_string(&self, token: &Token) -> String {
 728         self.token_to_string_ext(token, false)
 729     }
 730
 731     fn token_to_string_ext(&self, token: &Token, convert_dollar_crate: bool) -> String {
 732         let convert_dollar_crate = convert_dollar_crate.then_some(token.span);
 733         self.token_kind_to_string_ext(&token.kind, convert_dollar_crate)
 734     }
 735
 736     fn ty_to_string(&self, ty: &ast::Ty) -> String {
 737         self.to_string(|s| s.print_type(ty))
 738     }
 739
 740     fn bounds_to_string(&self, bounds: &[ast::GenericBound]) -> String {
 741         self.to_string(|s| s.print_type_bounds("", bounds))
 742     }
 743
 744     fn pat_to_string(&self, pat: &ast::Pat) -> String {
 745         self.to_string(|s| s.print_pat(pat))
 746     }
 747
 748     fn expr_to_string(&self, e: &ast::Expr) -> String {
 749         self.to_string(|s| s.print_expr(e))
 750     }
 751
 752     fn tt_to_string(&self, tt: &TokenTree) -> String {
 753         self.to_string(|s| s.print_tt(tt, false))
 754     }
 755
 756     fn tts_to_string(&self, tokens: &TokenStream) -> String {
 757         self.to_string(|s| s.print_tts(tokens, false))
 758     }
 759
 760     fn stmt_to_string(&self, stmt: &ast::Stmt) -> String {
 761         self.to_string(|s| s.print_stmt(stmt))
 762     }
 763
 764     fn item_to_string(&self, i: &ast::Item) -> String {
 765         self.to_string(|s| s.print_item(i))
 766     }
 767
 768     fn generic_params_to_string(&self, generic_params: &[ast::GenericParam]) -> String {
 769         self.to_string(|s| s.print_generic_params(generic_params))
 770     }
 771
 772     fn path_to_string(&self, p: &ast::Path) -> String {
 773         self.to_string(|s| s.print_path(p, false, 0))
 774     }
 775
 776     fn path_segment_to_string(&self, p: &ast::PathSegment) -> String {
 777         self.to_string(|s| s.print_path_segment(p, false))
 778     }
 779
 780     fn vis_to_string(&self, v: &ast::Visibility) -> String {
 781         self.to_string(|s| s.print_visibility(v))
 782     }
 783
 784     fn block_to_string(&self, blk: &ast::Block) -> String {
 785         self.to_string(|s| {
 786             // Containing cbox, will be closed by `print_block` at `}`.
 787             s.cbox(INDENT_UNIT);
 788             // Head-ibox, will be closed by `print_block` after `{`.
 789             s.ibox(0);
 790             s.print_block(blk)
 791         })
 792     }
 793
 794     fn meta_list_item_to_string(&self, li: &ast::NestedMetaItem) -> String {
 795         self.to_string(|s| s.print_meta_list_item(li))
 796     }
 797
 798     fn attr_item_to_string(&self, ai: &ast::AttrItem) -> String {
 799         self.to_string(|s| s.print_attr_item(ai, ai.path.span))
 800     }
 801
 802     fn attribute_to_string(&self, attr: &ast::Attribute) -> String {
 803         self.to_string(|s| s.print_attribute(attr))
 804     }
 805
 806     fn param_to_string(&self, arg: &ast::Param) -> String {
 807         self.to_string(|s| s.print_param(arg, false))
 808     }
 809
 810     fn to_string(&self, f: impl FnOnce(&mut State<'_>)) -> String {
 811         let mut printer = State::new();
 812         f(&mut printer);
 813         printer.s.eof()
 814     }
 815 }
 816
 817 impl<'a> PrintState<'a> for State<'a> {
 818     fn comments(&mut self) -> &mut Option<Comments<'a>> {
 819         &mut self.comments
 820     }
 821
 822     fn print_ident(&mut self, ident: Ident) {
 823         self.s.word(IdentPrinter::for_ast_ident(ident, ident.is_raw_guess()).to_string());
 824         self.ann.post(self, AnnNode::Ident(&ident))
 825     }
 826
 827     fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool) {
 828         if colons_before_params {
 829             self.s.word("::")
 830         }
 831
 832         match *args {
 833             ast::GenericArgs::AngleBracketed(ref data) => {
 834                 self.s.word("<");
 835                 self.commasep(Inconsistent, &data.args, |s, arg| match arg {
 836                     ast::AngleBracketedArg::Arg(a) => s.print_generic_arg(a),
 837                     ast::AngleBracketedArg::Constraint(c) => s.print_assoc_constraint(c),
 838                 });
 839                 self.s.word(">")
 840             }
 841
 842             ast::GenericArgs::Parenthesized(ref data) => {
 843                 self.s.word("(");
 844                 self.commasep(Inconsistent, &data.inputs, |s, ty| s.print_type(ty));
 845                 self.s.word(")");
 846                 self.print_fn_ret_ty(&data.output);
 847             }
 848         }
 849     }
 850 }
 851
 852 impl<'a> State<'a> {
 853     pub fn new() -> State<'a> {
 854         State { s: pp::mk_printer(), comments: None, ann: &NoAnn }
 855     }
 856
 857     // Synthesizes a comment that was not textually present in the original source
 858     // file.
 859     pub fn synth_comment(&mut self, text: String) {
 860         self.s.word("/*");
 861         self.s.space();
 862         self.s.word(text);
 863         self.s.space();
 864         self.s.word("*/")
 865     }
 866
 867     crate fn commasep_cmnt<T, F, G>(&mut self, b: Breaks, elts: &[T], mut op: F, mut get_span: G)
 868     where
 869         F: FnMut(&mut State<'_>, &T),
 870         G: FnMut(&T) -> rustc_span::Span,
 871     {
 872         self.rbox(0, b);
 873         let len = elts.len();
 874         let mut i = 0;
 875         for elt in elts {
 876             self.maybe_print_comment(get_span(elt).hi());
 877             op(self, elt);
 878             i += 1;
 879             if i < len {
 880                 self.s.word(",");
 881                 self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()));
 882                 self.space_if_not_bol();
 883             }
 884         }
 885         self.end();
 886     }
 887
 888     crate fn commasep_exprs(&mut self, b: Breaks, exprs: &[P<ast::Expr>]) {
 889         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(e), |e| e.span)
 890     }
 891
 892     crate fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod, attrs: &[ast::Attribute]) {
 893         self.print_inner_attributes(attrs);
 894         for item in &nmod.items {
 895             self.print_foreign_item(item);
 896         }
 897     }
 898
 899     pub fn print_opt_lifetime(&mut self, lifetime: &Option<ast::Lifetime>) {
 900         if let Some(lt) = *lifetime {
 901             self.print_lifetime(lt);
 902             self.nbsp();
 903         }
 904     }
 905
 906     pub fn print_assoc_constraint(&mut self, constraint: &ast::AssocTyConstraint) {
 907         self.print_ident(constraint.ident);
 908         constraint.gen_args.as_ref().map(|args| self.print_generic_args(args, false));
 909         self.s.space();
 910         match &constraint.kind {
 911             ast::AssocTyConstraintKind::Equality { ty } => {
 912                 self.word_space("=");
 913                 self.print_type(ty);
 914             }
 915             ast::AssocTyConstraintKind::Bound { bounds } => {
 916                 self.print_type_bounds(":", &*bounds);
 917             }
 918         }
 919     }
 920
 921     pub fn print_generic_arg(&mut self, generic_arg: &GenericArg) {
 922         match generic_arg {
 923             GenericArg::Lifetime(lt) => self.print_lifetime(*lt),
 924             GenericArg::Type(ty) => self.print_type(ty),
 925             GenericArg::Const(ct) => self.print_expr(&ct.value),
 926         }
 927     }
 928
 929     pub fn print_type(&mut self, ty: &ast::Ty) {
 930         self.maybe_print_comment(ty.span.lo());
 931         self.ibox(0);
 932         match ty.kind {
 933             ast::TyKind::Slice(ref ty) => {
 934                 self.s.word("[");
 935                 self.print_type(ty);
 936                 self.s.word("]");
 937             }
 938             ast::TyKind::Ptr(ref mt) => {
 939                 self.s.word("*");
 940                 self.print_mt(mt, true);
 941             }
 942             ast::TyKind::Rptr(ref lifetime, ref mt) => {
 943                 self.s.word("&");
 944                 self.print_opt_lifetime(lifetime);
 945                 self.print_mt(mt, false);
 946             }
 947             ast::TyKind::Never => {
 948                 self.s.word("!");
 949             }
 950             ast::TyKind::Tup(ref elts) => {
 951                 self.popen();
 952                 self.commasep(Inconsistent, &elts[..], |s, ty| s.print_type(ty));
 953                 if elts.len() == 1 {
 954                     self.s.word(",");
 955                 }
 956                 self.pclose();
 957             }
 958             ast::TyKind::Paren(ref typ) => {
 959                 self.popen();
 960                 self.print_type(typ);
 961                 self.pclose();
 962             }
 963             ast::TyKind::BareFn(ref f) => {
 964                 self.print_ty_fn(f.ext, f.unsafety, &f.decl, None, &f.generic_params);
 965             }
 966             ast::TyKind::Path(None, ref path) => {
 967                 self.print_path(path, false, 0);
 968             }
 969             ast::TyKind::Path(Some(ref qself), ref path) => self.print_qpath(path, qself, false),
 970             ast::TyKind::TraitObject(ref bounds, syntax) => {
 971                 let prefix = if syntax == ast::TraitObjectSyntax::Dyn { "dyn" } else { "" };
 972                 self.print_type_bounds(prefix, &bounds[..]);
 973             }
 974             ast::TyKind::ImplTrait(_, ref bounds) => {
 975                 self.print_type_bounds("impl", &bounds[..]);
 976             }
 977             ast::TyKind::Array(ref ty, ref length) => {
 978                 self.s.word("[");
 979                 self.print_type(ty);
 980                 self.s.word("; ");
 981                 self.print_expr(&length.value);
 982                 self.s.word("]");
 983             }
 984             ast::TyKind::Typeof(ref e) => {
 985                 self.s.word("typeof(");
 986                 self.print_expr(&e.value);
 987                 self.s.word(")");
 988             }
 989             ast::TyKind::Infer => {
 990                 self.s.word("_");
 991             }
 992             ast::TyKind::Err => {
 993                 self.popen();
 994                 self.s.word("/*ERROR*/");
 995                 self.pclose();
 996             }
 997             ast::TyKind::ImplicitSelf => {
 998                 self.s.word("Self");
 999             }
1000             ast::TyKind::MacCall(ref m) => {
1001                 self.print_mac(m);
1002             }
1003             ast::TyKind::CVarArgs => {
1004                 self.s.word("...");
1005             }
1006         }
1007         self.end();
1008     }
1009
1010     crate fn print_foreign_item(&mut self, item: &ast::ForeignItem) {
1011         let ast::Item { id, span, ident, ref attrs, ref kind, ref vis, tokens: _ } = *item;
1012         self.ann.pre(self, AnnNode::SubItem(id));
1013         self.hardbreak_if_not_bol();
1014         self.maybe_print_comment(span.lo());
1015         self.print_outer_attributes(attrs);
1016         match kind {
1017             ast::ForeignItemKind::Fn(box ast::FnKind(def, sig, gen, body)) => {
1018                 self.print_fn_full(sig, ident, gen, vis, *def, body.as_deref(), attrs);
1019             }
1020             ast::ForeignItemKind::Static(ty, mutbl, body) => {
1021                 let def = ast::Defaultness::Final;
1022                 self.print_item_const(ident, Some(*mutbl), ty, body.as_deref(), vis, def);
1023             }
1024             ast::ForeignItemKind::TyAlias(box ast::TyAliasKind(def, generics, bounds, ty)) => {
1025                 self.print_associated_type(ident, generics, bounds, ty.as_deref(), vis, *def);
1026             }
1027             ast::ForeignItemKind::MacCall(m) => {
1028                 self.print_mac(m);
1029                 if m.args.need_semicolon() {
1030                     self.s.word(";");
1031                 }
1032             }
1033         }
1034         self.ann.post(self, AnnNode::SubItem(id))
1035     }
1036
1037     fn print_item_const(
1038         &mut self,
1039         ident: Ident,
1040         mutbl: Option<ast::Mutability>,
1041         ty: &ast::Ty,
1042         body: Option<&ast::Expr>,
1043         vis: &ast::Visibility,
1044         defaultness: ast::Defaultness,
1045     ) {
1046         self.head("");
1047         self.print_visibility(vis);
1048         self.print_defaultness(defaultness);
1049         let leading = match mutbl {
1050             None => "const",
1051             Some(ast::Mutability::Not) => "static",
1052             Some(ast::Mutability::Mut) => "static mut",
1053         };
1054         self.word_space(leading);
1055         self.print_ident(ident);
1056         self.word_space(":");
1057         self.print_type(ty);
1058         self.s.space();
1059         self.end(); // end the head-ibox
1060         if let Some(body) = body {
1061             self.word_space("=");
1062             self.print_expr(body);
1063         }
1064         self.s.word(";");
1065         self.end(); // end the outer cbox
1066     }
1067
1068     fn print_associated_type(
1069         &mut self,
1070         ident: Ident,
1071         generics: &ast::Generics,
1072         bounds: &ast::GenericBounds,
1073         ty: Option<&ast::Ty>,
1074         vis: &ast::Visibility,
1075         defaultness: ast::Defaultness,
1076     ) {
1077         self.head("");
1078         self.print_visibility(vis);
1079         self.print_defaultness(defaultness);
1080         self.word_space("type");
1081         self.print_ident(ident);
1082         self.print_generic_params(&generics.params);
1083         self.print_type_bounds(":", bounds);
1084         self.print_where_clause(&generics.where_clause);
1085         if let Some(ty) = ty {
1086             self.s.space();
1087             self.word_space("=");
1088             self.print_type(ty);
1089         }
1090         self.s.word(";");
1091         self.end(); // end inner head-block
1092         self.end(); // end outer head-block
1093     }
1094
1095     /// Pretty-prints an item.
1096     crate fn print_item(&mut self, item: &ast::Item) {
1097         self.hardbreak_if_not_bol();
1098         self.maybe_print_comment(item.span.lo());
1099         self.print_outer_attributes(&item.attrs);
1100         self.ann.pre(self, AnnNode::Item(item));
1101         match item.kind {
1102             ast::ItemKind::ExternCrate(orig_name) => {
1103                 self.head(visibility_qualified(&item.vis, "extern crate"));
1104                 if let Some(orig_name) = orig_name {
1105                     self.print_name(orig_name);
1106                     self.s.space();
1107                     self.s.word("as");
1108                     self.s.space();
1109                 }
1110                 self.print_ident(item.ident);
1111                 self.s.word(";");
1112                 self.end(); // end inner head-block
1113                 self.end(); // end outer head-block
1114             }
1115             ast::ItemKind::Use(ref tree) => {
1116                 self.head(visibility_qualified(&item.vis, "use"));
1117                 self.print_use_tree(tree);
1118                 self.s.word(";");
1119                 self.end(); // end inner head-block
1120                 self.end(); // end outer head-block
1121             }
1122             ast::ItemKind::Static(ref ty, mutbl, ref body) => {
1123                 let def = ast::Defaultness::Final;
1124                 self.print_item_const(item.ident, Some(mutbl), ty, body.as_deref(), &item.vis, def);
1125             }
1126             ast::ItemKind::Const(def, ref ty, ref body) => {
1127                 self.print_item_const(item.ident, None, ty, body.as_deref(), &item.vis, def);
1128             }
1129             ast::ItemKind::Fn(box ast::FnKind(def, ref sig, ref gen, ref body)) => {
1130                 let body = body.as_deref();
1131                 self.print_fn_full(sig, item.ident, gen, &item.vis, def, body, &item.attrs);
1132             }
1133             ast::ItemKind::Mod(unsafety, ref mod_kind) => {
1134                 self.head(self.to_string(|s| {
1135                     s.print_visibility(&item.vis);
1136                     s.print_unsafety(unsafety);
1137                     s.word("mod");
1138                 }));
1139                 self.print_ident(item.ident);
1140
1141                 match mod_kind {
1142                     ModKind::Loaded(items, ..) => {
1143                         self.nbsp();
1144                         self.bopen();
1145                         self.print_inner_attributes(&item.attrs);
1146                         for item in items {
1147                             self.print_item(item);
1148                         }
1149                         self.bclose(item.span);
1150                     }
1151                     ModKind::Unloaded => {
1152                         self.s.word(";");
1153                         self.end(); // end inner head-block
1154                         self.end(); // end outer head-block
1155                     }
1156                 }
1157             }
1158             ast::ItemKind::ForeignMod(ref nmod) => {
1159                 self.head(self.to_string(|s| {
1160                     s.print_unsafety(nmod.unsafety);
1161                     s.word("extern");
1162                 }));
1163                 if let Some(abi) = nmod.abi {
1164                     self.print_literal(&abi.as_lit());
1165                     self.nbsp();
1166                 }
1167                 self.bopen();
1168                 self.print_foreign_mod(nmod, &item.attrs);
1169                 self.bclose(item.span);
1170             }
1171             ast::ItemKind::GlobalAsm(ref ga) => {
1172                 self.head(visibility_qualified(&item.vis, "global_asm!"));
1173                 self.s.word(ga.asm.to_string());
1174                 self.end();
1175             }
1176             ast::ItemKind::TyAlias(box ast::TyAliasKind(def, ref generics, ref bounds, ref ty)) => {
1177                 let ty = ty.as_deref();
1178                 self.print_associated_type(item.ident, generics, bounds, ty, &item.vis, def);
1179             }
1180             ast::ItemKind::Enum(ref enum_definition, ref params) => {
1181                 self.print_enum_def(enum_definition, params, item.ident, item.span, &item.vis);
1182             }
1183             ast::ItemKind::Struct(ref struct_def, ref generics) => {
1184                 self.head(visibility_qualified(&item.vis, "struct"));
1185                 self.print_struct(struct_def, generics, item.ident, item.span, true);
1186             }
1187             ast::ItemKind::Union(ref struct_def, ref generics) => {
1188                 self.head(visibility_qualified(&item.vis, "union"));
1189                 self.print_struct(struct_def, generics, item.ident, item.span, true);
1190             }
1191             ast::ItemKind::Impl(box ast::ImplKind {
1192                 unsafety,
1193                 polarity,
1194                 defaultness,
1195                 constness,
1196                 ref generics,
1197                 ref of_trait,
1198                 ref self_ty,
1199                 ref items,
1200             }) => {
1201                 self.head("");
1202                 self.print_visibility(&item.vis);
1203                 self.print_defaultness(defaultness);
1204                 self.print_unsafety(unsafety);
1205                 self.word_nbsp("impl");
1206                 self.print_constness(constness);
1207
1208                 if !generics.params.is_empty() {
1209                     self.print_generic_params(&generics.params);
1210                     self.s.space();
1211                 }
1212
1213                 if let ast::ImplPolarity::Negative(_) = polarity {
1214                     self.s.word("!");
1215                 }
1216
1217                 if let Some(ref t) = *of_trait {
1218                     self.print_trait_ref(t);
1219                     self.s.space();
1220                     self.word_space("for");
1221                 }
1222
1223                 self.print_type(self_ty);
1224                 self.print_where_clause(&generics.where_clause);
1225
1226                 self.s.space();
1227                 self.bopen();
1228                 self.print_inner_attributes(&item.attrs);
1229                 for impl_item in items {
1230                     self.print_assoc_item(impl_item);
1231                 }
1232                 self.bclose(item.span);
1233             }
1234             ast::ItemKind::Trait(box ast::TraitKind(
1235                 is_auto,
1236                 unsafety,
1237                 ref generics,
1238                 ref bounds,
1239                 ref trait_items,
1240             )) => {
1241                 self.head("");
1242                 self.print_visibility(&item.vis);
1243                 self.print_unsafety(unsafety);
1244                 self.print_is_auto(is_auto);
1245                 self.word_nbsp("trait");
1246                 self.print_ident(item.ident);
1247                 self.print_generic_params(&generics.params);
1248                 let mut real_bounds = Vec::with_capacity(bounds.len());
1249                 for b in bounds.iter() {
1250                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1251                         self.s.space();
1252                         self.word_space("for ?");
1253                         self.print_trait_ref(&ptr.trait_ref);
1254                     } else {
1255                         real_bounds.push(b.clone());
1256                     }
1257                 }
1258                 self.print_type_bounds(":", &real_bounds[..]);
1259                 self.print_where_clause(&generics.where_clause);
1260                 self.s.word(" ");
1261                 self.bopen();
1262                 self.print_inner_attributes(&item.attrs);
1263                 for trait_item in trait_items {
1264                     self.print_assoc_item(trait_item);
1265                 }
1266                 self.bclose(item.span);
1267             }
1268             ast::ItemKind::TraitAlias(ref generics, ref bounds) => {
1269                 self.head("");
1270                 self.print_visibility(&item.vis);
1271                 self.word_nbsp("trait");
1272                 self.print_ident(item.ident);
1273                 self.print_generic_params(&generics.params);
1274                 let mut real_bounds = Vec::with_capacity(bounds.len());
1275                 // FIXME(durka) this seems to be some quite outdated syntax
1276                 for b in bounds.iter() {
1277                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1278                         self.s.space();
1279                         self.word_space("for ?");
1280                         self.print_trait_ref(&ptr.trait_ref);
1281                     } else {
1282                         real_bounds.push(b.clone());
1283                     }
1284                 }
1285                 self.nbsp();
1286                 self.print_type_bounds("=", &real_bounds[..]);
1287                 self.print_where_clause(&generics.where_clause);
1288                 self.s.word(";");
1289             }
1290             ast::ItemKind::MacCall(ref mac) => {
1291                 self.print_mac(mac);
1292                 if mac.args.need_semicolon() {
1293                     self.s.word(";");
1294                 }
1295             }
1296             ast::ItemKind::MacroDef(ref macro_def) => {
1297                 let (kw, has_bang) = if macro_def.macro_rules {
1298                     ("macro_rules", true)
1299                 } else {
1300                     self.print_visibility(&item.vis);
1301                     ("macro", false)
1302                 };
1303                 self.print_mac_common(
1304                     Some(MacHeader::Keyword(kw)),
1305                     has_bang,
1306                     Some(item.ident),
1307                     macro_def.body.delim(),
1308                     &macro_def.body.inner_tokens(),
1309                     true,
1310                     item.span,
1311                 );
1312                 if macro_def.body.need_semicolon() {
1313                     self.word(";");
1314                 }
1315             }
1316         }
1317         self.ann.post(self, AnnNode::Item(item))
1318     }
1319
1320     fn print_trait_ref(&mut self, t: &ast::TraitRef) {
1321         self.print_path(&t.path, false, 0)
1322     }
1323
1324     fn print_formal_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
1325         if !generic_params.is_empty() {
1326             self.s.word("for");
1327             self.print_generic_params(generic_params);
1328             self.nbsp();
1329         }
1330     }
1331
1332     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) {
1333         self.print_formal_generic_params(&t.bound_generic_params);
1334         self.print_trait_ref(&t.trait_ref)
1335     }
1336
1337     crate fn print_enum_def(
1338         &mut self,
1339         enum_definition: &ast::EnumDef,
1340         generics: &ast::Generics,
1341         ident: Ident,
1342         span: rustc_span::Span,
1343         visibility: &ast::Visibility,
1344     ) {
1345         self.head(visibility_qualified(visibility, "enum"));
1346         self.print_ident(ident);
1347         self.print_generic_params(&generics.params);
1348         self.print_where_clause(&generics.where_clause);
1349         self.s.space();
1350         self.print_variants(&enum_definition.variants, span)
1351     }
1352
1353     crate fn print_variants(&mut self, variants: &[ast::Variant], span: rustc_span::Span) {
1354         self.bopen();
1355         for v in variants {
1356             self.space_if_not_bol();
1357             self.maybe_print_comment(v.span.lo());
1358             self.print_outer_attributes(&v.attrs);
1359             self.ibox(INDENT_UNIT);
1360             self.print_variant(v);
1361             self.s.word(",");
1362             self.end();
1363             self.maybe_print_trailing_comment(v.span, None);
1364         }
1365         self.bclose(span)
1366     }
1367
1368     crate fn print_visibility(&mut self, vis: &ast::Visibility) {
1369         match vis.kind {
1370             ast::VisibilityKind::Public => self.word_nbsp("pub"),
1371             ast::VisibilityKind::Crate(sugar) => match sugar {
1372                 ast::CrateSugar::PubCrate => self.word_nbsp("pub(crate)"),
1373                 ast::CrateSugar::JustCrate => self.word_nbsp("crate"),
1374             },
1375             ast::VisibilityKind::Restricted { ref path, .. } => {
1376                 let path = self.to_string(|s| s.print_path(path, false, 0));
1377                 if path == "self" || path == "super" {
1378                     self.word_nbsp(format!("pub({})", path))
1379                 } else {
1380                     self.word_nbsp(format!("pub(in {})", path))
1381                 }
1382             }
1383             ast::VisibilityKind::Inherited => {}
1384         }
1385     }
1386
1387     crate fn print_defaultness(&mut self, defaultness: ast::Defaultness) {
1388         if let ast::Defaultness::Default(_) = defaultness {
1389             self.word_nbsp("default");
1390         }
1391     }
1392
1393     crate fn print_struct(
1394         &mut self,
1395         struct_def: &ast::VariantData,
1396         generics: &ast::Generics,
1397         ident: Ident,
1398         span: rustc_span::Span,
1399         print_finalizer: bool,
1400     ) {
1401         self.print_ident(ident);
1402         self.print_generic_params(&generics.params);
1403         match struct_def {
1404             ast::VariantData::Tuple(..) | ast::VariantData::Unit(..) => {
1405                 if let ast::VariantData::Tuple(..) = struct_def {
1406                     self.popen();
1407                     self.commasep(Inconsistent, struct_def.fields(), |s, field| {
1408                         s.maybe_print_comment(field.span.lo());
1409                         s.print_outer_attributes(&field.attrs);
1410                         s.print_visibility(&field.vis);
1411                         s.print_type(&field.ty)
1412                     });
1413                     self.pclose();
1414                 }
1415                 self.print_where_clause(&generics.where_clause);
1416                 if print_finalizer {
1417                     self.s.word(";");
1418                 }
1419                 self.end();
1420                 self.end(); // Close the outer-box.
1421             }
1422             ast::VariantData::Struct(..) => {
1423                 self.print_where_clause(&generics.where_clause);
1424                 self.nbsp();
1425                 self.bopen();
1426                 self.hardbreak_if_not_bol();
1427
1428                 for field in struct_def.fields() {
1429                     self.hardbreak_if_not_bol();
1430                     self.maybe_print_comment(field.span.lo());
1431                     self.print_outer_attributes(&field.attrs);
1432                     self.print_visibility(&field.vis);
1433                     self.print_ident(field.ident.unwrap());
1434                     self.word_nbsp(":");
1435                     self.print_type(&field.ty);
1436                     self.s.word(",");
1437                 }
1438
1439                 self.bclose(span)
1440             }
1441         }
1442     }
1443
1444     crate fn print_variant(&mut self, v: &ast::Variant) {
1445         self.head("");
1446         self.print_visibility(&v.vis);
1447         let generics = ast::Generics::default();
1448         self.print_struct(&v.data, &generics, v.ident, v.span, false);
1449         if let Some(ref d) = v.disr_expr {
1450             self.s.space();
1451             self.word_space("=");
1452             self.print_expr(&d.value)
1453         }
1454     }
1455
1456     crate fn print_assoc_item(&mut self, item: &ast::AssocItem) {
1457         let ast::Item { id, span, ident, ref attrs, ref kind, ref vis, tokens: _ } = *item;
1458         self.ann.pre(self, AnnNode::SubItem(id));
1459         self.hardbreak_if_not_bol();
1460         self.maybe_print_comment(span.lo());
1461         self.print_outer_attributes(attrs);
1462         match kind {
1463             ast::AssocItemKind::Fn(box ast::FnKind(def, sig, gen, body)) => {
1464                 self.print_fn_full(sig, ident, gen, vis, *def, body.as_deref(), attrs);
1465             }
1466             ast::AssocItemKind::Const(def, ty, body) => {
1467                 self.print_item_const(ident, None, ty, body.as_deref(), vis, *def);
1468             }
1469             ast::AssocItemKind::TyAlias(box ast::TyAliasKind(def, generics, bounds, ty)) => {
1470                 self.print_associated_type(ident, generics, bounds, ty.as_deref(), vis, *def);
1471             }
1472             ast::AssocItemKind::MacCall(m) => {
1473                 self.print_mac(m);
1474                 if m.args.need_semicolon() {
1475                     self.s.word(";");
1476                 }
1477             }
1478         }
1479         self.ann.post(self, AnnNode::SubItem(id))
1480     }
1481
1482     crate fn print_stmt(&mut self, st: &ast::Stmt) {
1483         self.maybe_print_comment(st.span.lo());
1484         match st.kind {
1485             ast::StmtKind::Local(ref loc) => {
1486                 self.print_outer_attributes(&loc.attrs);
1487                 self.space_if_not_bol();
1488                 self.ibox(INDENT_UNIT);
1489                 self.word_nbsp("let");
1490
1491                 self.ibox(INDENT_UNIT);
1492                 self.print_local_decl(loc);
1493                 self.end();
1494                 if let Some(ref init) = loc.init {
1495                     self.nbsp();
1496                     self.word_space("=");
1497                     self.print_expr(init);
1498                 }
1499                 self.s.word(";");
1500                 self.end();
1501             }
1502             ast::StmtKind::Item(ref item) => self.print_item(item),
1503             ast::StmtKind::Expr(ref expr) => {
1504                 self.space_if_not_bol();
1505                 self.print_expr_outer_attr_style(expr, false);
1506                 if classify::expr_requires_semi_to_be_stmt(expr) {
1507                     self.s.word(";");
1508                 }
1509             }
1510             ast::StmtKind::Semi(ref expr) => {
1511                 self.space_if_not_bol();
1512                 self.print_expr_outer_attr_style(expr, false);
1513                 self.s.word(";");
1514             }
1515             ast::StmtKind::Empty => {
1516                 self.space_if_not_bol();
1517                 self.s.word(";");
1518             }
1519             ast::StmtKind::MacCall(ref mac) => {
1520                 self.space_if_not_bol();
1521                 self.print_outer_attributes(&mac.attrs);
1522                 self.print_mac(&mac.mac);
1523                 if mac.style == ast::MacStmtStyle::Semicolon {
1524                     self.s.word(";");
1525                 }
1526             }
1527         }
1528         self.maybe_print_trailing_comment(st.span, None)
1529     }
1530
1531     crate fn print_block(&mut self, blk: &ast::Block) {
1532         self.print_block_with_attrs(blk, &[])
1533     }
1534
1535     crate fn print_block_unclosed_indent(&mut self, blk: &ast::Block) {
1536         self.print_block_maybe_unclosed(blk, &[], false)
1537     }
1538
1539     crate fn print_block_with_attrs(&mut self, blk: &ast::Block, attrs: &[ast::Attribute]) {
1540         self.print_block_maybe_unclosed(blk, attrs, true)
1541     }
1542
1543     crate fn print_block_maybe_unclosed(
1544         &mut self,
1545         blk: &ast::Block,
1546         attrs: &[ast::Attribute],
1547         close_box: bool,
1548     ) {
1549         match blk.rules {
1550             BlockCheckMode::Unsafe(..) => self.word_space("unsafe"),
1551             BlockCheckMode::Default => (),
1552         }
1553         self.maybe_print_comment(blk.span.lo());
1554         self.ann.pre(self, AnnNode::Block(blk));
1555         self.bopen();
1556
1557         self.print_inner_attributes(attrs);
1558
1559         for (i, st) in blk.stmts.iter().enumerate() {
1560             match st.kind {
1561                 ast::StmtKind::Expr(ref expr) if i == blk.stmts.len() - 1 => {
1562                     self.maybe_print_comment(st.span.lo());
1563                     self.space_if_not_bol();
1564                     self.print_expr_outer_attr_style(expr, false);
1565                     self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
1566                 }
1567                 _ => self.print_stmt(st),
1568             }
1569         }
1570
1571         self.bclose_maybe_open(blk.span, close_box);
1572         self.ann.post(self, AnnNode::Block(blk))
1573     }
1574
1575     /// Print a `let pat = scrutinee` expression.
1576     crate fn print_let(&mut self, pat: &ast::Pat, scrutinee: &ast::Expr) {
1577         self.s.word("let ");
1578
1579         self.print_pat(pat);
1580         self.s.space();
1581
1582         self.word_space("=");
1583         self.print_expr_cond_paren(
1584             scrutinee,
1585             Self::cond_needs_par(scrutinee)
1586                 || parser::needs_par_as_let_scrutinee(scrutinee.precedence().order()),
1587         )
1588     }
1589
1590     fn print_else(&mut self, els: Option<&ast::Expr>) {
1591         if let Some(_else) = els {
1592             match _else.kind {
1593                 // Another `else if` block.
1594                 ast::ExprKind::If(ref i, ref then, ref e) => {
1595                     self.cbox(INDENT_UNIT - 1);
1596                     self.ibox(0);
1597                     self.s.word(" else if ");
1598                     self.print_expr_as_cond(i);
1599                     self.s.space();
1600                     self.print_block(then);
1601                     self.print_else(e.as_deref())
1602                 }
1603                 // Final `else` block.
1604                 ast::ExprKind::Block(ref b, _) => {
1605                     self.cbox(INDENT_UNIT - 1);
1606                     self.ibox(0);
1607                     self.s.word(" else ");
1608                     self.print_block(b)
1609                 }
1610                 // Constraints would be great here!
1611                 _ => {
1612                     panic!("print_if saw if with weird alternative");
1613                 }
1614             }
1615         }
1616     }
1617
1618     crate fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block, elseopt: Option<&ast::Expr>) {
1619         self.head("if");
1620
1621         self.print_expr_as_cond(test);
1622         self.s.space();
1623
1624         self.print_block(blk);
1625         self.print_else(elseopt)
1626     }
1627
1628     crate fn print_mac(&mut self, m: &ast::MacCall) {
1629         self.print_mac_common(
1630             Some(MacHeader::Path(&m.path)),
1631             true,
1632             None,
1633             m.args.delim(),
1634             &m.args.inner_tokens(),
1635             true,
1636             m.span(),
1637         );
1638     }
1639
1640     fn print_call_post(&mut self, args: &[P<ast::Expr>]) {
1641         self.popen();
1642         self.commasep_exprs(Inconsistent, args);
1643         self.pclose()
1644     }
1645
1646     crate fn print_expr_maybe_paren(&mut self, expr: &ast::Expr, prec: i8) {
1647         self.print_expr_cond_paren(expr, expr.precedence().order() < prec)
1648     }
1649
1650     /// Prints an expr using syntax that's acceptable in a condition position, such as the `cond` in
1651     /// `if cond { ... }`.
1652     crate fn print_expr_as_cond(&mut self, expr: &ast::Expr) {
1653         self.print_expr_cond_paren(expr, Self::cond_needs_par(expr))
1654     }
1655
1656     /// Does `expr` need parenthesis when printed in a condition position?
1657     fn cond_needs_par(expr: &ast::Expr) -> bool {
1658         match expr.kind {
1659             // These cases need parens due to the parse error observed in #26461: `if return {}`
1660             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1661             ast::ExprKind::Closure(..) | ast::ExprKind::Ret(..) | ast::ExprKind::Break(..) => true,
1662
1663             _ => parser::contains_exterior_struct_lit(expr),
1664         }
1665     }
1666
1667     /// Prints `expr` or `(expr)` when `needs_par` holds.
1668     fn print_expr_cond_paren(&mut self, expr: &ast::Expr, needs_par: bool) {
1669         if needs_par {
1670             self.popen();
1671         }
1672         self.print_expr(expr);
1673         if needs_par {
1674             self.pclose();
1675         }
1676     }
1677
1678     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>], attrs: &[ast::Attribute]) {
1679         self.ibox(INDENT_UNIT);
1680         self.s.word("[");
1681         self.print_inner_attributes_inline(attrs);
1682         self.commasep_exprs(Inconsistent, exprs);
1683         self.s.word("]");
1684         self.end();
1685     }
1686
1687     fn print_expr_anon_const(&mut self, expr: &ast::AnonConst, attrs: &[ast::Attribute]) {
1688         self.ibox(INDENT_UNIT);
1689         self.s.word("const");
1690         self.print_inner_attributes_inline(attrs);
1691         self.print_expr(&expr.value);
1692         self.end();
1693     }
1694
1695     fn print_expr_repeat(
1696         &mut self,
1697         element: &ast::Expr,
1698         count: &ast::AnonConst,
1699         attrs: &[ast::Attribute],
1700     ) {
1701         self.ibox(INDENT_UNIT);
1702         self.s.word("[");
1703         self.print_inner_attributes_inline(attrs);
1704         self.print_expr(element);
1705         self.word_space(";");
1706         self.print_expr(&count.value);
1707         self.s.word("]");
1708         self.end();
1709     }
1710
1711     fn print_expr_struct(
1712         &mut self,
1713         path: &ast::Path,
1714         fields: &[ast::ExprField],
1715         rest: &ast::StructRest,
1716         attrs: &[ast::Attribute],
1717     ) {
1718         self.print_path(path, true, 0);
1719         self.s.word("{");
1720         self.print_inner_attributes_inline(attrs);
1721         self.commasep_cmnt(
1722             Consistent,
1723             fields,
1724             |s, field| {
1725                 s.print_outer_attributes(&field.attrs);
1726                 s.ibox(INDENT_UNIT);
1727                 if !field.is_shorthand {
1728                     s.print_ident(field.ident);
1729                     s.word_space(":");
1730                 }
1731                 s.print_expr(&field.expr);
1732                 s.end();
1733             },
1734             |f| f.span,
1735         );
1736         match rest {
1737             ast::StructRest::Base(_) | ast::StructRest::Rest(_) => {
1738                 self.ibox(INDENT_UNIT);
1739                 if !fields.is_empty() {
1740                     self.s.word(",");
1741                     self.s.space();
1742                 }
1743                 self.s.word("..");
1744                 if let ast::StructRest::Base(ref expr) = *rest {
1745                     self.print_expr(expr);
1746                 }
1747                 self.end();
1748             }
1749             ast::StructRest::None if !fields.is_empty() => self.s.word(","),
1750             _ => {}
1751         }
1752         self.s.word("}");
1753     }
1754
1755     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>], attrs: &[ast::Attribute]) {
1756         self.popen();
1757         self.print_inner_attributes_inline(attrs);
1758         self.commasep_exprs(Inconsistent, exprs);
1759         if exprs.len() == 1 {
1760             self.s.word(",");
1761         }
1762         self.pclose()
1763     }
1764
1765     fn print_expr_call(&mut self, func: &ast::Expr, args: &[P<ast::Expr>]) {
1766         let prec = match func.kind {
1767             ast::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1768             _ => parser::PREC_POSTFIX,
1769         };
1770
1771         self.print_expr_maybe_paren(func, prec);
1772         self.print_call_post(args)
1773     }
1774
1775     fn print_expr_method_call(&mut self, segment: &ast::PathSegment, args: &[P<ast::Expr>]) {
1776         let base_args = &args[1..];
1777         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
1778         self.s.word(".");
1779         self.print_ident(segment.ident);
1780         if let Some(ref args) = segment.args {
1781             self.print_generic_args(args, true);
1782         }
1783         self.print_call_post(base_args)
1784     }
1785
1786     fn print_expr_binary(&mut self, op: ast::BinOp, lhs: &ast::Expr, rhs: &ast::Expr) {
1787         let assoc_op = AssocOp::from_ast_binop(op.node);
1788         let prec = assoc_op.precedence() as i8;
1789         let fixity = assoc_op.fixity();
1790
1791         let (left_prec, right_prec) = match fixity {
1792             Fixity::Left => (prec, prec + 1),
1793             Fixity::Right => (prec + 1, prec),
1794             Fixity::None => (prec + 1, prec + 1),
1795         };
1796
1797         let left_prec = match (&lhs.kind, op.node) {
1798             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1799             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1800             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1801             (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Lt | ast::BinOpKind::Shl) => {
1802                 parser::PREC_FORCE_PAREN
1803             }
1804             // We are given `(let _ = a) OP b`.
1805             //
1806             // - When `OP <= LAnd` we should print `let _ = a OP b` to avoid redundant parens
1807             //   as the parser will interpret this as `(let _ = a) OP b`.
1808             //
1809             // - Otherwise, e.g. when we have `(let a = b) < c` in AST,
1810             //   parens are required since the parser would interpret `let a = b < c` as
1811             //   `let a = (b < c)`. To achieve this, we force parens.
1812             (&ast::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(prec) => {
1813                 parser::PREC_FORCE_PAREN
1814             }
1815             _ => left_prec,
1816         };
1817
1818         self.print_expr_maybe_paren(lhs, left_prec);
1819         self.s.space();
1820         self.word_space(op.node.to_string());
1821         self.print_expr_maybe_paren(rhs, right_prec)
1822     }
1823
1824     fn print_expr_unary(&mut self, op: ast::UnOp, expr: &ast::Expr) {
1825         self.s.word(ast::UnOp::to_string(op));
1826         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1827     }
1828
1829     fn print_expr_addr_of(
1830         &mut self,
1831         kind: ast::BorrowKind,
1832         mutability: ast::Mutability,
1833         expr: &ast::Expr,
1834     ) {
1835         self.s.word("&");
1836         match kind {
1837             ast::BorrowKind::Ref => self.print_mutability(mutability, false),
1838             ast::BorrowKind::Raw => {
1839                 self.word_nbsp("raw");
1840                 self.print_mutability(mutability, true);
1841             }
1842         }
1843         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1844     }
1845
1846     pub fn print_expr(&mut self, expr: &ast::Expr) {
1847         self.print_expr_outer_attr_style(expr, true)
1848     }
1849
1850     fn print_expr_outer_attr_style(&mut self, expr: &ast::Expr, is_inline: bool) {
1851         self.maybe_print_comment(expr.span.lo());
1852
1853         let attrs = &expr.attrs;
1854         if is_inline {
1855             self.print_outer_attributes_inline(attrs);
1856         } else {
1857             self.print_outer_attributes(attrs);
1858         }
1859
1860         self.ibox(INDENT_UNIT);
1861         self.ann.pre(self, AnnNode::Expr(expr));
1862         match expr.kind {
1863             ast::ExprKind::Box(ref expr) => {
1864                 self.word_space("box");
1865                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX);
1866             }
1867             ast::ExprKind::Array(ref exprs) => {
1868                 self.print_expr_vec(&exprs[..], attrs);
1869             }
1870             ast::ExprKind::ConstBlock(ref anon_const) => {
1871                 self.print_expr_anon_const(anon_const, attrs);
1872             }
1873             ast::ExprKind::Repeat(ref element, ref count) => {
1874                 self.print_expr_repeat(element, count, attrs);
1875             }
1876             ast::ExprKind::Struct(ref se) => {
1877                 self.print_expr_struct(&se.path, &se.fields, &se.rest, attrs);
1878             }
1879             ast::ExprKind::Tup(ref exprs) => {
1880                 self.print_expr_tup(&exprs[..], attrs);
1881             }
1882             ast::ExprKind::Call(ref func, ref args) => {
1883                 self.print_expr_call(func, &args[..]);
1884             }
1885             ast::ExprKind::MethodCall(ref segment, ref args, _) => {
1886                 self.print_expr_method_call(segment, &args[..]);
1887             }
1888             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
1889                 self.print_expr_binary(op, lhs, rhs);
1890             }
1891             ast::ExprKind::Unary(op, ref expr) => {
1892                 self.print_expr_unary(op, expr);
1893             }
1894             ast::ExprKind::AddrOf(k, m, ref expr) => {
1895                 self.print_expr_addr_of(k, m, expr);
1896             }
1897             ast::ExprKind::Lit(ref lit) => {
1898                 self.print_literal(lit);
1899             }
1900             ast::ExprKind::Cast(ref expr, ref ty) => {
1901                 let prec = AssocOp::As.precedence() as i8;
1902                 self.print_expr_maybe_paren(expr, prec);
1903                 self.s.space();
1904                 self.word_space("as");
1905                 self.print_type(ty);
1906             }
1907             ast::ExprKind::Type(ref expr, ref ty) => {
1908                 let prec = AssocOp::Colon.precedence() as i8;
1909                 self.print_expr_maybe_paren(expr, prec);
1910                 self.word_space(":");
1911                 self.print_type(ty);
1912             }
1913             ast::ExprKind::Let(ref pat, ref scrutinee) => {
1914                 self.print_let(pat, scrutinee);
1915             }
1916             ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
1917                 self.print_if(test, blk, elseopt.as_deref())
1918             }
1919             ast::ExprKind::While(ref test, ref blk, opt_label) => {
1920                 if let Some(label) = opt_label {
1921                     self.print_ident(label.ident);
1922                     self.word_space(":");
1923                 }
1924                 self.head("while");
1925                 self.print_expr_as_cond(test);
1926                 self.s.space();
1927                 self.print_block_with_attrs(blk, attrs);
1928             }
1929             ast::ExprKind::ForLoop(ref pat, ref iter, ref blk, opt_label) => {
1930                 if let Some(label) = opt_label {
1931                     self.print_ident(label.ident);
1932                     self.word_space(":");
1933                 }
1934                 self.head("for");
1935                 self.print_pat(pat);
1936                 self.s.space();
1937                 self.word_space("in");
1938                 self.print_expr_as_cond(iter);
1939                 self.s.space();
1940                 self.print_block_with_attrs(blk, attrs);
1941             }
1942             ast::ExprKind::Loop(ref blk, opt_label) => {
1943                 if let Some(label) = opt_label {
1944                     self.print_ident(label.ident);
1945                     self.word_space(":");
1946                 }
1947                 self.head("loop");
1948                 self.s.space();
1949                 self.print_block_with_attrs(blk, attrs);
1950             }
1951             ast::ExprKind::Match(ref expr, ref arms) => {
1952                 self.cbox(INDENT_UNIT);
1953                 self.ibox(INDENT_UNIT);
1954                 self.word_nbsp("match");
1955                 self.print_expr_as_cond(expr);
1956                 self.s.space();
1957                 self.bopen();
1958                 self.print_inner_attributes_no_trailing_hardbreak(attrs);
1959                 for arm in arms {
1960                     self.print_arm(arm);
1961                 }
1962                 self.bclose(expr.span);
1963             }
1964             ast::ExprKind::Closure(
1965                 capture_clause,
1966                 asyncness,
1967                 movability,
1968                 ref decl,
1969                 ref body,
1970                 _,
1971             ) => {
1972                 self.print_movability(movability);
1973                 self.print_asyncness(asyncness);
1974                 self.print_capture_clause(capture_clause);
1975
1976                 self.print_fn_params_and_ret(decl, true);
1977                 self.s.space();
1978                 self.print_expr(body);
1979                 self.end(); // need to close a box
1980
1981                 // a box will be closed by print_expr, but we didn't want an overall
1982                 // wrapper so we closed the corresponding opening. so create an
1983                 // empty box to satisfy the close.
1984                 self.ibox(0);
1985             }
1986             ast::ExprKind::Block(ref blk, opt_label) => {
1987                 if let Some(label) = opt_label {
1988                     self.print_ident(label.ident);
1989                     self.word_space(":");
1990                 }
1991                 // containing cbox, will be closed by print-block at }
1992                 self.cbox(INDENT_UNIT);
1993                 // head-box, will be closed by print-block after {
1994                 self.ibox(0);
1995                 self.print_block_with_attrs(blk, attrs);
1996             }
1997             ast::ExprKind::Async(capture_clause, _, ref blk) => {
1998                 self.word_nbsp("async");
1999                 self.print_capture_clause(capture_clause);
2000                 self.s.space();
2001                 // cbox/ibox in analogy to the `ExprKind::Block` arm above
2002                 self.cbox(INDENT_UNIT);
2003                 self.ibox(0);
2004                 self.print_block_with_attrs(blk, attrs);
2005             }
2006             ast::ExprKind::Await(ref expr) => {
2007                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2008                 self.s.word(".await");
2009             }
2010             ast::ExprKind::Assign(ref lhs, ref rhs, _) => {
2011                 let prec = AssocOp::Assign.precedence() as i8;
2012                 self.print_expr_maybe_paren(lhs, prec + 1);
2013                 self.s.space();
2014                 self.word_space("=");
2015                 self.print_expr_maybe_paren(rhs, prec);
2016             }
2017             ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
2018                 let prec = AssocOp::Assign.precedence() as i8;
2019                 self.print_expr_maybe_paren(lhs, prec + 1);
2020                 self.s.space();
2021                 self.s.word(op.node.to_string());
2022                 self.word_space("=");
2023                 self.print_expr_maybe_paren(rhs, prec);
2024             }
2025             ast::ExprKind::Field(ref expr, ident) => {
2026                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2027                 self.s.word(".");
2028                 self.print_ident(ident);
2029             }
2030             ast::ExprKind::Index(ref expr, ref index) => {
2031                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2032                 self.s.word("[");
2033                 self.print_expr(index);
2034                 self.s.word("]");
2035             }
2036             ast::ExprKind::Range(ref start, ref end, limits) => {
2037                 // Special case for `Range`.  `AssocOp` claims that `Range` has higher precedence
2038                 // than `Assign`, but `x .. x = x` gives a parse error instead of `x .. (x = x)`.
2039                 // Here we use a fake precedence value so that any child with lower precedence than
2040                 // a "normal" binop gets parenthesized.  (`LOr` is the lowest-precedence binop.)
2041                 let fake_prec = AssocOp::LOr.precedence() as i8;
2042                 if let Some(ref e) = *start {
2043                     self.print_expr_maybe_paren(e, fake_prec);
2044                 }
2045                 if limits == ast::RangeLimits::HalfOpen {
2046                     self.s.word("..");
2047                 } else {
2048                     self.s.word("..=");
2049                 }
2050                 if let Some(ref e) = *end {
2051                     self.print_expr_maybe_paren(e, fake_prec);
2052                 }
2053             }
2054             ast::ExprKind::Underscore => self.s.word("_"),
2055             ast::ExprKind::Path(None, ref path) => self.print_path(path, true, 0),
2056             ast::ExprKind::Path(Some(ref qself), ref path) => self.print_qpath(path, qself, true),
2057             ast::ExprKind::Break(opt_label, ref opt_expr) => {
2058                 self.s.word("break");
2059                 self.s.space();
2060                 if let Some(label) = opt_label {
2061                     self.print_ident(label.ident);
2062                     self.s.space();
2063                 }
2064                 if let Some(ref expr) = *opt_expr {
2065                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2066                     self.s.space();
2067                 }
2068             }
2069             ast::ExprKind::Continue(opt_label) => {
2070                 self.s.word("continue");
2071                 self.s.space();
2072                 if let Some(label) = opt_label {
2073                     self.print_ident(label.ident);
2074                     self.s.space()
2075                 }
2076             }
2077             ast::ExprKind::Ret(ref result) => {
2078                 self.s.word("return");
2079                 if let Some(ref expr) = *result {
2080                     self.s.word(" ");
2081                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2082                 }
2083             }
2084             ast::ExprKind::InlineAsm(ref a) => {
2085                 enum AsmArg<'a> {
2086                     Template(String),
2087                     Operand(&'a InlineAsmOperand),
2088                     Options(InlineAsmOptions),
2089                 }
2090
2091                 let mut args = vec![];
2092                 args.push(AsmArg::Template(InlineAsmTemplatePiece::to_string(&a.template)));
2093                 args.extend(a.operands.iter().map(|(o, _)| AsmArg::Operand(o)));
2094                 if !a.options.is_empty() {
2095                     args.push(AsmArg::Options(a.options));
2096                 }
2097
2098                 self.word("asm!");
2099                 self.popen();
2100                 self.commasep(Consistent, &args, |s, arg| match arg {
2101                     AsmArg::Template(template) => s.print_string(&template, ast::StrStyle::Cooked),
2102                     AsmArg::Operand(op) => {
2103                         let print_reg_or_class = |s: &mut Self, r: &InlineAsmRegOrRegClass| match r
2104                         {
2105                             InlineAsmRegOrRegClass::Reg(r) => {
2106                                 s.print_symbol(*r, ast::StrStyle::Cooked)
2107                             }
2108                             InlineAsmRegOrRegClass::RegClass(r) => s.word(r.to_string()),
2109                         };
2110                         match op {
2111                             InlineAsmOperand::In { reg, expr } => {
2112                                 s.word("in");
2113                                 s.popen();
2114                                 print_reg_or_class(s, reg);
2115                                 s.pclose();
2116                                 s.space();
2117                                 s.print_expr(expr);
2118                             }
2119                             InlineAsmOperand::Out { reg, late, expr } => {
2120                                 s.word(if *late { "lateout" } else { "out" });
2121                                 s.popen();
2122                                 print_reg_or_class(s, reg);
2123                                 s.pclose();
2124                                 s.space();
2125                                 match expr {
2126                                     Some(expr) => s.print_expr(expr),
2127                                     None => s.word("_"),
2128                                 }
2129                             }
2130                             InlineAsmOperand::InOut { reg, late, expr } => {
2131                                 s.word(if *late { "inlateout" } else { "inout" });
2132                                 s.popen();
2133                                 print_reg_or_class(s, reg);
2134                                 s.pclose();
2135                                 s.space();
2136                                 s.print_expr(expr);
2137                             }
2138                             InlineAsmOperand::SplitInOut { reg, late, in_expr, out_expr } => {
2139                                 s.word(if *late { "inlateout" } else { "inout" });
2140                                 s.popen();
2141                                 print_reg_or_class(s, reg);
2142                                 s.pclose();
2143                                 s.space();
2144                                 s.print_expr(in_expr);
2145                                 s.space();
2146                                 s.word_space("=>");
2147                                 match out_expr {
2148                                     Some(out_expr) => s.print_expr(out_expr),
2149                                     None => s.word("_"),
2150                                 }
2151                             }
2152                             InlineAsmOperand::Const { expr } => {
2153                                 s.word("const");
2154                                 s.space();
2155                                 s.print_expr(expr);
2156                             }
2157                             InlineAsmOperand::Sym { expr } => {
2158                                 s.word("sym");
2159                                 s.space();
2160                                 s.print_expr(expr);
2161                             }
2162                         }
2163                     }
2164                     AsmArg::Options(opts) => {
2165                         s.word("options");
2166                         s.popen();
2167                         let mut options = vec![];
2168                         if opts.contains(InlineAsmOptions::PURE) {
2169                             options.push("pure");
2170                         }
2171                         if opts.contains(InlineAsmOptions::NOMEM) {
2172                             options.push("nomem");
2173                         }
2174                         if opts.contains(InlineAsmOptions::READONLY) {
2175                             options.push("readonly");
2176                         }
2177                         if opts.contains(InlineAsmOptions::PRESERVES_FLAGS) {
2178                             options.push("preserves_flags");
2179                         }
2180                         if opts.contains(InlineAsmOptions::NORETURN) {
2181                             options.push("noreturn");
2182                         }
2183                         if opts.contains(InlineAsmOptions::NOSTACK) {
2184                             options.push("nostack");
2185                         }
2186                         if opts.contains(InlineAsmOptions::ATT_SYNTAX) {
2187                             options.push("att_syntax");
2188                         }
2189                         s.commasep(Inconsistent, &options, |s, &opt| {
2190                             s.word(opt);
2191                         });
2192                         s.pclose();
2193                     }
2194                 });
2195                 self.pclose();
2196             }
2197             ast::ExprKind::LlvmInlineAsm(ref a) => {
2198                 self.s.word("llvm_asm!");
2199                 self.popen();
2200                 self.print_symbol(a.asm, a.asm_str_style);
2201                 self.word_space(":");
2202
2203                 self.commasep(Inconsistent, &a.outputs, |s, out| {
2204                     let constraint = out.constraint.as_str();
2205                     let mut ch = constraint.chars();
2206                     match ch.next() {
2207                         Some('=') if out.is_rw => {
2208                             s.print_string(&format!("+{}", ch.as_str()), ast::StrStyle::Cooked)
2209                         }
2210                         _ => s.print_string(&constraint, ast::StrStyle::Cooked),
2211                     }
2212                     s.popen();
2213                     s.print_expr(&out.expr);
2214                     s.pclose();
2215                 });
2216                 self.s.space();
2217                 self.word_space(":");
2218
2219                 self.commasep(Inconsistent, &a.inputs, |s, &(co, ref o)| {
2220                     s.print_symbol(co, ast::StrStyle::Cooked);
2221                     s.popen();
2222                     s.print_expr(o);
2223                     s.pclose();
2224                 });
2225                 self.s.space();
2226                 self.word_space(":");
2227
2228                 self.commasep(Inconsistent, &a.clobbers, |s, &co| {
2229                     s.print_symbol(co, ast::StrStyle::Cooked);
2230                 });
2231
2232                 let mut options = vec![];
2233                 if a.volatile {
2234                     options.push("volatile");
2235                 }
2236                 if a.alignstack {
2237                     options.push("alignstack");
2238                 }
2239                 if a.dialect == ast::LlvmAsmDialect::Intel {
2240                     options.push("intel");
2241                 }
2242
2243                 if !options.is_empty() {
2244                     self.s.space();
2245                     self.word_space(":");
2246                     self.commasep(Inconsistent, &options, |s, &co| {
2247                         s.print_string(co, ast::StrStyle::Cooked);
2248                     });
2249                 }
2250
2251                 self.pclose();
2252             }
2253             ast::ExprKind::MacCall(ref m) => self.print_mac(m),
2254             ast::ExprKind::Paren(ref e) => {
2255                 self.popen();
2256                 self.print_inner_attributes_inline(attrs);
2257                 self.print_expr(e);
2258                 self.pclose();
2259             }
2260             ast::ExprKind::Yield(ref e) => {
2261                 self.s.word("yield");
2262
2263                 if let Some(ref expr) = *e {
2264                     self.s.space();
2265                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2266                 }
2267             }
2268             ast::ExprKind::Try(ref e) => {
2269                 self.print_expr_maybe_paren(e, parser::PREC_POSTFIX);
2270                 self.s.word("?")
2271             }
2272             ast::ExprKind::TryBlock(ref blk) => {
2273                 self.head("try");
2274                 self.s.space();
2275                 self.print_block_with_attrs(blk, attrs)
2276             }
2277             ast::ExprKind::Err => {
2278                 self.popen();
2279                 self.s.word("/*ERROR*/");
2280                 self.pclose()
2281             }
2282         }
2283         self.ann.post(self, AnnNode::Expr(expr));
2284         self.end();
2285     }
2286
2287     crate fn print_local_decl(&mut self, loc: &ast::Local) {
2288         self.print_pat(&loc.pat);
2289         if let Some(ref ty) = loc.ty {
2290             self.word_space(":");
2291             self.print_type(ty);
2292         }
2293     }
2294
2295     pub fn print_usize(&mut self, i: usize) {
2296         self.s.word(i.to_string())
2297     }
2298
2299     crate fn print_name(&mut self, name: Symbol) {
2300         self.s.word(name.to_string());
2301         self.ann.post(self, AnnNode::Name(&name))
2302     }
2303
2304     fn print_qpath(&mut self, path: &ast::Path, qself: &ast::QSelf, colons_before_params: bool) {
2305         self.s.word("<");
2306         self.print_type(&qself.ty);
2307         if qself.position > 0 {
2308             self.s.space();
2309             self.word_space("as");
2310             let depth = path.segments.len() - qself.position;
2311             self.print_path(path, false, depth);
2312         }
2313         self.s.word(">");
2314         for item_segment in &path.segments[qself.position..] {
2315             self.s.word("::");
2316             self.print_ident(item_segment.ident);
2317             if let Some(ref args) = item_segment.args {
2318                 self.print_generic_args(args, colons_before_params)
2319             }
2320         }
2321     }
2322
2323     crate fn print_pat(&mut self, pat: &ast::Pat) {
2324         self.maybe_print_comment(pat.span.lo());
2325         self.ann.pre(self, AnnNode::Pat(pat));
2326         /* Pat isn't normalized, but the beauty of it
2327         is that it doesn't matter */
2328         match pat.kind {
2329             PatKind::Wild => self.s.word("_"),
2330             PatKind::Ident(binding_mode, ident, ref sub) => {
2331                 match binding_mode {
2332                     ast::BindingMode::ByRef(mutbl) => {
2333                         self.word_nbsp("ref");
2334                         self.print_mutability(mutbl, false);
2335                     }
2336                     ast::BindingMode::ByValue(ast::Mutability::Not) => {}
2337                     ast::BindingMode::ByValue(ast::Mutability::Mut) => {
2338                         self.word_nbsp("mut");
2339                     }
2340                 }
2341                 self.print_ident(ident);
2342                 if let Some(ref p) = *sub {
2343                     self.s.space();
2344                     self.s.word_space("@");
2345                     self.print_pat(p);
2346                 }
2347             }
2348             PatKind::TupleStruct(ref path, ref elts) => {
2349                 self.print_path(path, true, 0);
2350                 self.popen();
2351                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2352                 self.pclose();
2353             }
2354             PatKind::Or(ref pats) => {
2355                 self.strsep("|", true, Inconsistent, &pats[..], |s, p| s.print_pat(p));
2356             }
2357             PatKind::Path(None, ref path) => {
2358                 self.print_path(path, true, 0);
2359             }
2360             PatKind::Path(Some(ref qself), ref path) => {
2361                 self.print_qpath(path, qself, false);
2362             }
2363             PatKind::Struct(ref path, ref fields, etc) => {
2364                 self.print_path(path, true, 0);
2365                 self.nbsp();
2366                 self.word_space("{");
2367                 self.commasep_cmnt(
2368                     Consistent,
2369                     &fields[..],
2370                     |s, f| {
2371                         s.cbox(INDENT_UNIT);
2372                         if !f.is_shorthand {
2373                             s.print_ident(f.ident);
2374                             s.word_nbsp(":");
2375                         }
2376                         s.print_pat(&f.pat);
2377                         s.end();
2378                     },
2379                     |f| f.pat.span,
2380                 );
2381                 if etc {
2382                     if !fields.is_empty() {
2383                         self.word_space(",");
2384                     }
2385                     self.s.word("..");
2386                 }
2387                 self.s.space();
2388                 self.s.word("}");
2389             }
2390             PatKind::Tuple(ref elts) => {
2391                 self.popen();
2392                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2393                 if elts.len() == 1 {
2394                     self.s.word(",");
2395                 }
2396                 self.pclose();
2397             }
2398             PatKind::Box(ref inner) => {
2399                 self.s.word("box ");
2400                 self.print_pat(inner);
2401             }
2402             PatKind::Ref(ref inner, mutbl) => {
2403                 self.s.word("&");
2404                 if mutbl == ast::Mutability::Mut {
2405                     self.s.word("mut ");
2406                 }
2407                 if let PatKind::Ident(ast::BindingMode::ByValue(ast::Mutability::Mut), ..) =
2408                     inner.kind
2409                 {
2410                     self.popen();
2411                     self.print_pat(inner);
2412                     self.pclose();
2413                 } else {
2414                     self.print_pat(inner);
2415                 }
2416             }
2417             PatKind::Lit(ref e) => self.print_expr(&**e),
2418             PatKind::Range(ref begin, ref end, Spanned { node: ref end_kind, .. }) => {
2419                 if let Some(e) = begin {
2420                     self.print_expr(e);
2421                     self.s.space();
2422                 }
2423                 match *end_kind {
2424                     RangeEnd::Included(RangeSyntax::DotDotDot) => self.s.word("..."),
2425                     RangeEnd::Included(RangeSyntax::DotDotEq) => self.s.word("..="),
2426                     RangeEnd::Excluded => self.s.word(".."),
2427                 }
2428                 if let Some(e) = end {
2429                     self.print_expr(e);
2430                 }
2431             }
2432             PatKind::Slice(ref elts) => {
2433                 self.s.word("[");
2434                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2435                 self.s.word("]");
2436             }
2437             PatKind::Rest => self.s.word(".."),
2438             PatKind::Paren(ref inner) => {
2439                 self.popen();
2440                 self.print_pat(inner);
2441                 self.pclose();
2442             }
2443             PatKind::MacCall(ref m) => self.print_mac(m),
2444         }
2445         self.ann.post(self, AnnNode::Pat(pat))
2446     }
2447
2448     fn print_arm(&mut self, arm: &ast::Arm) {
2449         // Note, I have no idea why this check is necessary, but here it is.
2450         if arm.attrs.is_empty() {
2451             self.s.space();
2452         }
2453         self.cbox(INDENT_UNIT);
2454         self.ibox(0);
2455         self.maybe_print_comment(arm.pat.span.lo());
2456         self.print_outer_attributes(&arm.attrs);
2457         self.print_pat(&arm.pat);
2458         self.s.space();
2459         if let Some(ref e) = arm.guard {
2460             self.word_space("if");
2461             self.print_expr(e);
2462             self.s.space();
2463         }
2464         self.word_space("=>");
2465
2466         match arm.body.kind {
2467             ast::ExprKind::Block(ref blk, opt_label) => {
2468                 if let Some(label) = opt_label {
2469                     self.print_ident(label.ident);
2470                     self.word_space(":");
2471                 }
2472
2473                 // The block will close the pattern's ibox.
2474                 self.print_block_unclosed_indent(blk);
2475
2476                 // If it is a user-provided unsafe block, print a comma after it.
2477                 if let BlockCheckMode::Unsafe(ast::UserProvided) = blk.rules {
2478                     self.s.word(",");
2479                 }
2480             }
2481             _ => {
2482                 self.end(); // Close the ibox for the pattern.
2483                 self.print_expr(&arm.body);
2484                 self.s.word(",");
2485             }
2486         }
2487         self.end(); // Close enclosing cbox.
2488     }
2489
2490     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) {
2491         match explicit_self.node {
2492             SelfKind::Value(m) => {
2493                 self.print_mutability(m, false);
2494                 self.s.word("self")
2495             }
2496             SelfKind::Region(ref lt, m) => {
2497                 self.s.word("&");
2498                 self.print_opt_lifetime(lt);
2499                 self.print_mutability(m, false);
2500                 self.s.word("self")
2501             }
2502             SelfKind::Explicit(ref typ, m) => {
2503                 self.print_mutability(m, false);
2504                 self.s.word("self");
2505                 self.word_space(":");
2506                 self.print_type(typ)
2507             }
2508         }
2509     }
2510
2511     fn print_fn_full(
2512         &mut self,
2513         sig: &ast::FnSig,
2514         name: Ident,
2515         generics: &ast::Generics,
2516         vis: &ast::Visibility,
2517         defaultness: ast::Defaultness,
2518         body: Option<&ast::Block>,
2519         attrs: &[ast::Attribute],
2520     ) {
2521         if body.is_some() {
2522             self.head("");
2523         }
2524         self.print_visibility(vis);
2525         self.print_defaultness(defaultness);
2526         self.print_fn(&sig.decl, sig.header, Some(name), generics);
2527         if let Some(body) = body {
2528             self.nbsp();
2529             self.print_block_with_attrs(body, attrs);
2530         } else {
2531             self.s.word(";");
2532         }
2533     }
2534
2535     crate fn print_fn(
2536         &mut self,
2537         decl: &ast::FnDecl,
2538         header: ast::FnHeader,
2539         name: Option<Ident>,
2540         generics: &ast::Generics,
2541     ) {
2542         self.print_fn_header_info(header);
2543         if let Some(name) = name {
2544             self.nbsp();
2545             self.print_ident(name);
2546         }
2547         self.print_generic_params(&generics.params);
2548         self.print_fn_params_and_ret(decl, false);
2549         self.print_where_clause(&generics.where_clause)
2550     }
2551
2552     crate fn print_fn_params_and_ret(&mut self, decl: &ast::FnDecl, is_closure: bool) {
2553         let (open, close) = if is_closure { ("|", "|") } else { ("(", ")") };
2554         self.word(open);
2555         self.commasep(Inconsistent, &decl.inputs, |s, param| s.print_param(param, is_closure));
2556         self.word(close);
2557         self.print_fn_ret_ty(&decl.output)
2558     }
2559
2560     crate fn print_movability(&mut self, movability: ast::Movability) {
2561         match movability {
2562             ast::Movability::Static => self.word_space("static"),
2563             ast::Movability::Movable => {}
2564         }
2565     }
2566
2567     crate fn print_asyncness(&mut self, asyncness: ast::Async) {
2568         if asyncness.is_async() {
2569             self.word_nbsp("async");
2570         }
2571     }
2572
2573     crate fn print_capture_clause(&mut self, capture_clause: ast::CaptureBy) {
2574         match capture_clause {
2575             ast::CaptureBy::Value => self.word_space("move"),
2576             ast::CaptureBy::Ref => {}
2577         }
2578     }
2579
2580     pub fn print_type_bounds(&mut self, prefix: &'static str, bounds: &[ast::GenericBound]) {
2581         if !bounds.is_empty() {
2582             self.s.word(prefix);
2583             let mut first = true;
2584             for bound in bounds {
2585                 if !(first && prefix.is_empty()) {
2586                     self.nbsp();
2587                 }
2588                 if first {
2589                     first = false;
2590                 } else {
2591                     self.word_space("+");
2592                 }
2593
2594                 match bound {
2595                     GenericBound::Trait(tref, modifier) => {
2596                         if modifier == &TraitBoundModifier::Maybe {
2597                             self.s.word("?");
2598                         }
2599                         self.print_poly_trait_ref(tref);
2600                     }
2601                     GenericBound::Outlives(lt) => self.print_lifetime(*lt),
2602                 }
2603             }
2604         }
2605     }
2606
2607     crate fn print_lifetime(&mut self, lifetime: ast::Lifetime) {
2608         self.print_name(lifetime.ident.name)
2609     }
2610
2611     crate fn print_lifetime_bounds(
2612         &mut self,
2613         lifetime: ast::Lifetime,
2614         bounds: &ast::GenericBounds,
2615     ) {
2616         self.print_lifetime(lifetime);
2617         if !bounds.is_empty() {
2618             self.s.word(": ");
2619             for (i, bound) in bounds.iter().enumerate() {
2620                 if i != 0 {
2621                     self.s.word(" + ");
2622                 }
2623                 match bound {
2624                     ast::GenericBound::Outlives(lt) => self.print_lifetime(*lt),
2625                     _ => panic!(),
2626                 }
2627             }
2628         }
2629     }
2630
2631     crate fn print_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
2632         if generic_params.is_empty() {
2633             return;
2634         }
2635
2636         self.s.word("<");
2637
2638         self.commasep(Inconsistent, &generic_params, |s, param| {
2639             s.print_outer_attributes_inline(&param.attrs);
2640
2641             match param.kind {
2642                 ast::GenericParamKind::Lifetime => {
2643                     let lt = ast::Lifetime { id: param.id, ident: param.ident };
2644                     s.print_lifetime_bounds(lt, &param.bounds)
2645                 }
2646                 ast::GenericParamKind::Type { ref default } => {
2647                     s.print_ident(param.ident);
2648                     s.print_type_bounds(":", &param.bounds);
2649                     if let Some(ref default) = default {
2650                         s.s.space();
2651                         s.word_space("=");
2652                         s.print_type(default)
2653                     }
2654                 }
2655                 ast::GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
2656                     s.word_space("const");
2657                     s.print_ident(param.ident);
2658                     s.s.space();
2659                     s.word_space(":");
2660                     s.print_type(ty);
2661                     s.print_type_bounds(":", &param.bounds);
2662                     // FIXME(const_generic_defaults)
2663                     if let Some(ref _default) = default {
2664                         // FIXME(const_generics_defaults): print the `default` value here
2665                         s.s.space();
2666                         s.word_space("=");
2667                         // s.print_anon_const(&default);
2668                     }
2669                 }
2670             }
2671         });
2672
2673         self.s.word(">");
2674     }
2675
2676     crate fn print_where_clause(&mut self, where_clause: &ast::WhereClause) {
2677         if where_clause.predicates.is_empty() && !where_clause.has_where_token {
2678             return;
2679         }
2680
2681         self.s.space();
2682         self.word_space("where");
2683
2684         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2685             if i != 0 {
2686                 self.word_space(",");
2687             }
2688
2689             match *predicate {
2690                 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
2691                     ref bound_generic_params,
2692                     ref bounded_ty,
2693                     ref bounds,
2694                     ..
2695                 }) => {
2696                     self.print_formal_generic_params(bound_generic_params);
2697                     self.print_type(bounded_ty);
2698                     self.print_type_bounds(":", bounds);
2699                 }
2700                 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
2701                     ref lifetime,
2702                     ref bounds,
2703                     ..
2704                 }) => {
2705                     self.print_lifetime_bounds(*lifetime, bounds);
2706                 }
2707                 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
2708                     ref lhs_ty,
2709                     ref rhs_ty,
2710                     ..
2711                 }) => {
2712                     self.print_type(lhs_ty);
2713                     self.s.space();
2714                     self.word_space("=");
2715                     self.print_type(rhs_ty);
2716                 }
2717             }
2718         }
2719     }
2720
2721     crate fn print_use_tree(&mut self, tree: &ast::UseTree) {
2722         match tree.kind {
2723             ast::UseTreeKind::Simple(rename, ..) => {
2724                 self.print_path(&tree.prefix, false, 0);
2725                 if let Some(rename) = rename {
2726                     self.s.space();
2727                     self.word_space("as");
2728                     self.print_ident(rename);
2729                 }
2730             }
2731             ast::UseTreeKind::Glob => {
2732                 if !tree.prefix.segments.is_empty() {
2733                     self.print_path(&tree.prefix, false, 0);
2734                     self.s.word("::");
2735                 }
2736                 self.s.word("*");
2737             }
2738             ast::UseTreeKind::Nested(ref items) => {
2739                 if tree.prefix.segments.is_empty() {
2740                     self.s.word("{");
2741                 } else {
2742                     self.print_path(&tree.prefix, false, 0);
2743                     self.s.word("::{");
2744                 }
2745                 self.commasep(Inconsistent, &items[..], |this, &(ref tree, _)| {
2746                     this.print_use_tree(tree)
2747                 });
2748                 self.s.word("}");
2749             }
2750         }
2751     }
2752
2753     pub fn print_mutability(&mut self, mutbl: ast::Mutability, print_const: bool) {
2754         match mutbl {
2755             ast::Mutability::Mut => self.word_nbsp("mut"),
2756             ast::Mutability::Not => {
2757                 if print_const {
2758                     self.word_nbsp("const");
2759                 }
2760             }
2761         }
2762     }
2763
2764     crate fn print_mt(&mut self, mt: &ast::MutTy, print_const: bool) {
2765         self.print_mutability(mt.mutbl, print_const);
2766         self.print_type(&mt.ty)
2767     }
2768
2769     crate fn print_param(&mut self, input: &ast::Param, is_closure: bool) {
2770         self.ibox(INDENT_UNIT);
2771
2772         self.print_outer_attributes_inline(&input.attrs);
2773
2774         match input.ty.kind {
2775             ast::TyKind::Infer if is_closure => self.print_pat(&input.pat),
2776             _ => {
2777                 if let Some(eself) = input.to_self() {
2778                     self.print_explicit_self(&eself);
2779                 } else {
2780                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.kind {
2781                         ident.name == kw::Empty
2782                     } else {
2783                         false
2784                     };
2785                     if !invalid {
2786                         self.print_pat(&input.pat);
2787                         self.s.word(":");
2788                         self.s.space();
2789                     }
2790                     self.print_type(&input.ty);
2791                 }
2792             }
2793         }
2794         self.end();
2795     }
2796
2797     crate fn print_fn_ret_ty(&mut self, fn_ret_ty: &ast::FnRetTy) {
2798         if let ast::FnRetTy::Ty(ty) = fn_ret_ty {
2799             self.space_if_not_bol();
2800             self.ibox(INDENT_UNIT);
2801             self.word_space("->");
2802             self.print_type(ty);
2803             self.end();
2804             self.maybe_print_comment(ty.span.lo());
2805         }
2806     }
2807
2808     crate fn print_ty_fn(
2809         &mut self,
2810         ext: ast::Extern,
2811         unsafety: ast::Unsafe,
2812         decl: &ast::FnDecl,
2813         name: Option<Ident>,
2814         generic_params: &[ast::GenericParam],
2815     ) {
2816         self.ibox(INDENT_UNIT);
2817         if !generic_params.is_empty() {
2818             self.s.word("for");
2819             self.print_generic_params(generic_params);
2820         }
2821         let generics = ast::Generics {
2822             params: Vec::new(),
2823             where_clause: ast::WhereClause {
2824                 has_where_token: false,
2825                 predicates: Vec::new(),
2826                 span: rustc_span::DUMMY_SP,
2827             },
2828             span: rustc_span::DUMMY_SP,
2829         };
2830         let header = ast::FnHeader { unsafety, ext, ..ast::FnHeader::default() };
2831         self.print_fn(decl, header, name, &generics);
2832         self.end();
2833     }
2834
2835     crate fn maybe_print_trailing_comment(
2836         &mut self,
2837         span: rustc_span::Span,
2838         next_pos: Option<BytePos>,
2839     ) {
2840         if let Some(cmnts) = self.comments() {
2841             if let Some(cmnt) = cmnts.trailing_comment(span, next_pos) {
2842                 self.print_comment(&cmnt);
2843             }
2844         }
2845     }
2846
2847     crate fn print_remaining_comments(&mut self) {
2848         // If there aren't any remaining comments, then we need to manually
2849         // make sure there is a line break at the end.
2850         if self.next_comment().is_none() {
2851             self.s.hardbreak();
2852         }
2853         while let Some(ref cmnt) = self.next_comment() {
2854             self.print_comment(cmnt);
2855         }
2856     }
2857
2858     crate fn print_fn_header_info(&mut self, header: ast::FnHeader) {
2859         self.print_constness(header.constness);
2860         self.print_asyncness(header.asyncness);
2861         self.print_unsafety(header.unsafety);
2862
2863         match header.ext {
2864             ast::Extern::None => {}
2865             ast::Extern::Implicit => {
2866                 self.word_nbsp("extern");
2867             }
2868             ast::Extern::Explicit(abi) => {
2869                 self.word_nbsp("extern");
2870                 self.print_literal(&abi.as_lit());
2871                 self.nbsp();
2872             }
2873         }
2874
2875         self.s.word("fn")
2876     }
2877
2878     crate fn print_unsafety(&mut self, s: ast::Unsafe) {
2879         match s {
2880             ast::Unsafe::No => {}
2881             ast::Unsafe::Yes(_) => self.word_nbsp("unsafe"),
2882         }
2883     }
2884
2885     crate fn print_constness(&mut self, s: ast::Const) {
2886         match s {
2887             ast::Const::No => {}
2888             ast::Const::Yes(_) => self.word_nbsp("const"),
2889         }
2890     }
2891
2892     crate fn print_is_auto(&mut self, s: ast::IsAuto) {
2893         match s {
2894             ast::IsAuto::Yes => self.word_nbsp("auto"),
2895             ast::IsAuto::No => {}
2896         }
2897     }
2898 }