src/librustc_ast_pretty/pprust.rs

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