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::{dummy_spanned, SourceMap, Spanned};
   6 use rustc_span::symbol::{kw, sym};
   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     cm: &'a SourceMap,
  51     comments: Vec<comments::Comment>,
  52     current: usize,
  53 }
  54
  55 impl<'a> Comments<'a> {
  56     pub fn new(cm: &'a SourceMap, filename: FileName, input: String) -> Comments<'a> {
  57         let comments = comments::gather_comments(cm, filename, input);
  58         Comments { cm, 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.cm.lookup_char_pos(span.hi());
  75             let comment_line = self.cm.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     cm: &'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(cm, 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 an ident from AST, `$crate` is converted into its respective crate name.
 200 pub fn ast_ident_to_string(ident: ast::Ident, is_raw: bool) -> String {
 201     ident_to_string(ident.name, is_raw, Some(ident.span))
 202 }
 203
 204 // AST pretty-printer is used as a fallback for turning AST structures into token streams for
 205 // proc macros. Additionally, proc macros may stringify their input and expect it survive the
 206 // stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
 207 // So we need to somehow pretty-print `$crate` in a way preserving at least some of its
 208 // hygiene data, most importantly name of the crate it refers to.
 209 // As a result we print `$crate` as `crate` if it refers to the local crate
 210 // and as `::other_crate_name` if it refers to some other crate.
 211 // Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
 212 // but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
 213 // so we should not perform this lossy conversion if the top level call to the pretty-printer was
 214 // done for a token stream or a single token.
 215 fn ident_to_string(name: ast::Name, is_raw: bool, convert_dollar_crate: Option<Span>) -> String {
 216     if is_raw {
 217         format!("r#{}", name)
 218     } else {
 219         if name == kw::DollarCrate {
 220             if let Some(span) = convert_dollar_crate {
 221                 let converted = span.ctxt().dollar_crate_name();
 222                 return if converted.is_path_segment_keyword() {
 223                     converted.to_string()
 224                 } else {
 225                     format!("::{}", converted)
 226                 };
 227             }
 228         }
 229         name.to_string()
 230     }
 231 }
 232
 233 /// Print the token kind precisely, without converting `$crate` into its respective crate name.
 234 pub fn token_kind_to_string(tok: &TokenKind) -> String {
 235     token_kind_to_string_ext(tok, None)
 236 }
 237
 238 fn token_kind_to_string_ext(tok: &TokenKind, convert_dollar_crate: Option<Span>) -> String {
 239     match *tok {
 240         token::Eq => "=".to_string(),
 241         token::Lt => "<".to_string(),
 242         token::Le => "<=".to_string(),
 243         token::EqEq => "==".to_string(),
 244         token::Ne => "!=".to_string(),
 245         token::Ge => ">=".to_string(),
 246         token::Gt => ">".to_string(),
 247         token::Not => "!".to_string(),
 248         token::Tilde => "~".to_string(),
 249         token::OrOr => "||".to_string(),
 250         token::AndAnd => "&&".to_string(),
 251         token::BinOp(op) => binop_to_string(op).to_string(),
 252         token::BinOpEq(op) => format!("{}=", binop_to_string(op)),
 253
 254         /* Structural symbols */
 255         token::At => "@".to_string(),
 256         token::Dot => ".".to_string(),
 257         token::DotDot => "..".to_string(),
 258         token::DotDotDot => "...".to_string(),
 259         token::DotDotEq => "..=".to_string(),
 260         token::Comma => ",".to_string(),
 261         token::Semi => ";".to_string(),
 262         token::Colon => ":".to_string(),
 263         token::ModSep => "::".to_string(),
 264         token::RArrow => "->".to_string(),
 265         token::LArrow => "<-".to_string(),
 266         token::FatArrow => "=>".to_string(),
 267         token::OpenDelim(token::Paren) => "(".to_string(),
 268         token::CloseDelim(token::Paren) => ")".to_string(),
 269         token::OpenDelim(token::Bracket) => "[".to_string(),
 270         token::CloseDelim(token::Bracket) => "]".to_string(),
 271         token::OpenDelim(token::Brace) => "{".to_string(),
 272         token::CloseDelim(token::Brace) => "}".to_string(),
 273         token::OpenDelim(token::NoDelim) | token::CloseDelim(token::NoDelim) => " ".to_string(),
 274         token::Pound => "#".to_string(),
 275         token::Dollar => "$".to_string(),
 276         token::Question => "?".to_string(),
 277         token::SingleQuote => "'".to_string(),
 278
 279         /* Literals */
 280         token::Literal(lit) => literal_to_string(lit),
 281
 282         /* Name components */
 283         token::Ident(s, is_raw) => ident_to_string(s, is_raw, convert_dollar_crate),
 284         token::Lifetime(s) => s.to_string(),
 285
 286         /* Other */
 287         token::DocComment(s) => s.to_string(),
 288         token::Eof => "<eof>".to_string(),
 289         token::Whitespace => " ".to_string(),
 290         token::Comment => "/* */".to_string(),
 291         token::Shebang(s) => format!("/* shebang: {}*/", s),
 292         token::Unknown(s) => s.to_string(),
 293
 294         token::Interpolated(ref nt) => nonterminal_to_string(nt),
 295     }
 296 }
 297
 298 /// Print the token precisely, without converting `$crate` into its respective crate name.
 299 pub fn token_to_string(token: &Token) -> String {
 300     token_to_string_ext(token, false)
 301 }
 302
 303 fn token_to_string_ext(token: &Token, convert_dollar_crate: bool) -> String {
 304     let convert_dollar_crate = convert_dollar_crate.then_some(token.span);
 305     token_kind_to_string_ext(&token.kind, convert_dollar_crate)
 306 }
 307
 308 pub fn nonterminal_to_string(nt: &Nonterminal) -> String {
 309     match *nt {
 310         token::NtExpr(ref e) => expr_to_string(e),
 311         token::NtMeta(ref e) => attr_item_to_string(e),
 312         token::NtTy(ref e) => ty_to_string(e),
 313         token::NtPath(ref e) => path_to_string(e),
 314         token::NtItem(ref e) => item_to_string(e),
 315         token::NtBlock(ref e) => block_to_string(e),
 316         token::NtStmt(ref e) => stmt_to_string(e),
 317         token::NtPat(ref e) => pat_to_string(e),
 318         token::NtIdent(e, is_raw) => ast_ident_to_string(e, is_raw),
 319         token::NtLifetime(e) => e.to_string(),
 320         token::NtLiteral(ref e) => expr_to_string(e),
 321         token::NtTT(ref tree) => tt_to_string(tree.clone()),
 322         // FIXME(Centril): merge these variants.
 323         token::NtImplItem(ref e) | token::NtTraitItem(ref e) => assoc_item_to_string(e),
 324         token::NtVis(ref e) => vis_to_string(e),
 325         token::NtForeignItem(ref e) => foreign_item_to_string(e),
 326     }
 327 }
 328
 329 pub fn ty_to_string(ty: &ast::Ty) -> String {
 330     to_string(|s| s.print_type(ty))
 331 }
 332
 333 pub fn bounds_to_string(bounds: &[ast::GenericBound]) -> String {
 334     to_string(|s| s.print_type_bounds("", bounds))
 335 }
 336
 337 pub fn pat_to_string(pat: &ast::Pat) -> String {
 338     to_string(|s| s.print_pat(pat))
 339 }
 340
 341 pub fn expr_to_string(e: &ast::Expr) -> String {
 342     to_string(|s| s.print_expr(e))
 343 }
 344
 345 pub fn tt_to_string(tt: tokenstream::TokenTree) -> String {
 346     to_string(|s| s.print_tt(tt, false))
 347 }
 348
 349 pub fn tts_to_string(tokens: TokenStream) -> String {
 350     to_string(|s| s.print_tts(tokens, false))
 351 }
 352
 353 pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
 354     to_string(|s| s.print_stmt(stmt))
 355 }
 356
 357 pub fn item_to_string(i: &ast::Item) -> String {
 358     to_string(|s| s.print_item(i))
 359 }
 360
 361 fn assoc_item_to_string(i: &ast::AssocItem) -> String {
 362     to_string(|s| s.print_assoc_item(i))
 363 }
 364
 365 pub fn generic_params_to_string(generic_params: &[ast::GenericParam]) -> String {
 366     to_string(|s| s.print_generic_params(generic_params))
 367 }
 368
 369 pub fn path_to_string(p: &ast::Path) -> String {
 370     to_string(|s| s.print_path(p, false, 0))
 371 }
 372
 373 pub fn path_segment_to_string(p: &ast::PathSegment) -> String {
 374     to_string(|s| s.print_path_segment(p, false))
 375 }
 376
 377 pub fn vis_to_string(v: &ast::Visibility) -> String {
 378     to_string(|s| s.print_visibility(v))
 379 }
 380
 381 fn block_to_string(blk: &ast::Block) -> String {
 382     to_string(|s| {
 383         // Containing cbox, will be closed by `print_block` at `}`.
 384         s.cbox(INDENT_UNIT);
 385         // Head-ibox, will be closed by `print_block` after `{`.
 386         s.ibox(0);
 387         s.print_block(blk)
 388     })
 389 }
 390
 391 pub fn meta_list_item_to_string(li: &ast::NestedMetaItem) -> String {
 392     to_string(|s| s.print_meta_list_item(li))
 393 }
 394
 395 fn attr_item_to_string(ai: &ast::AttrItem) -> String {
 396     to_string(|s| s.print_attr_item(ai, ai.path.span))
 397 }
 398
 399 pub fn attribute_to_string(attr: &ast::Attribute) -> String {
 400     to_string(|s| s.print_attribute(attr))
 401 }
 402
 403 pub fn param_to_string(arg: &ast::Param) -> String {
 404     to_string(|s| s.print_param(arg, false))
 405 }
 406
 407 fn foreign_item_to_string(arg: &ast::ForeignItem) -> String {
 408     to_string(|s| s.print_foreign_item(arg))
 409 }
 410
 411 fn visibility_qualified(vis: &ast::Visibility, s: &str) -> String {
 412     format!("{}{}", to_string(|s| s.print_visibility(vis)), s)
 413 }
 414
 415 impl std::ops::Deref for State<'_> {
 416     type Target = pp::Printer;
 417     fn deref(&self) -> &Self::Target {
 418         &self.s
 419     }
 420 }
 421
 422 impl std::ops::DerefMut for State<'_> {
 423     fn deref_mut(&mut self) -> &mut Self::Target {
 424         &mut self.s
 425     }
 426 }
 427
 428 pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::DerefMut {
 429     fn comments(&mut self) -> &mut Option<Comments<'a>>;
 430     fn print_ident(&mut self, ident: ast::Ident);
 431     fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool);
 432
 433     fn strsep<T, F>(
 434         &mut self,
 435         sep: &'static str,
 436         space_before: bool,
 437         b: Breaks,
 438         elts: &[T],
 439         mut op: F,
 440     ) where
 441         F: FnMut(&mut Self, &T),
 442     {
 443         self.rbox(0, b);
 444         if let Some((first, rest)) = elts.split_first() {
 445             op(self, first);
 446             for elt in rest {
 447                 if space_before {
 448                     self.space();
 449                 }
 450                 self.word_space(sep);
 451                 op(self, elt);
 452             }
 453         }
 454         self.end();
 455     }
 456
 457     fn commasep<T, F>(&mut self, b: Breaks, elts: &[T], op: F)
 458     where
 459         F: FnMut(&mut Self, &T),
 460     {
 461         self.strsep(",", false, b, elts, op)
 462     }
 463
 464     fn maybe_print_comment(&mut self, pos: BytePos) {
 465         while let Some(ref cmnt) = self.next_comment() {
 466             if cmnt.pos < pos {
 467                 self.print_comment(cmnt);
 468             } else {
 469                 break;
 470             }
 471         }
 472     }
 473
 474     fn print_comment(&mut self, cmnt: &comments::Comment) {
 475         match cmnt.style {
 476             comments::Mixed => {
 477                 assert_eq!(cmnt.lines.len(), 1);
 478                 self.zerobreak();
 479                 self.word(cmnt.lines[0].clone());
 480                 self.zerobreak()
 481             }
 482             comments::Isolated => {
 483                 self.hardbreak_if_not_bol();
 484                 for line in &cmnt.lines {
 485                     // Don't print empty lines because they will end up as trailing
 486                     // whitespace.
 487                     if !line.is_empty() {
 488                         self.word(line.clone());
 489                     }
 490                     self.hardbreak();
 491                 }
 492             }
 493             comments::Trailing => {
 494                 if !self.is_beginning_of_line() {
 495                     self.word(" ");
 496                 }
 497                 if cmnt.lines.len() == 1 {
 498                     self.word(cmnt.lines[0].clone());
 499                     self.hardbreak()
 500                 } else {
 501                     self.ibox(0);
 502                     for line in &cmnt.lines {
 503                         if !line.is_empty() {
 504                             self.word(line.clone());
 505                         }
 506                         self.hardbreak();
 507                     }
 508                     self.end();
 509                 }
 510             }
 511             comments::BlankLine => {
 512                 // We need to do at least one, possibly two hardbreaks.
 513                 let twice = match self.last_token() {
 514                     pp::Token::String(s) => ";" == s,
 515                     pp::Token::Begin(_) => true,
 516                     pp::Token::End => true,
 517                     _ => false,
 518                 };
 519                 if twice {
 520                     self.hardbreak();
 521                 }
 522                 self.hardbreak();
 523             }
 524         }
 525         if let Some(cm) = self.comments() {
 526             cm.current += 1;
 527         }
 528     }
 529
 530     fn next_comment(&mut self) -> Option<comments::Comment> {
 531         self.comments().as_mut().and_then(|c| c.next())
 532     }
 533
 534     fn print_literal(&mut self, lit: &ast::Lit) {
 535         self.maybe_print_comment(lit.span.lo());
 536         self.word(lit.token.to_string())
 537     }
 538
 539     fn print_string(&mut self, st: &str, style: ast::StrStyle) {
 540         let st = match style {
 541             ast::StrStyle::Cooked => (format!("\"{}\"", st.escape_debug())),
 542             ast::StrStyle::Raw(n) => {
 543                 format!("r{delim}\"{string}\"{delim}", delim = "#".repeat(n as usize), string = st)
 544             }
 545         };
 546         self.word(st)
 547     }
 548
 549     fn print_inner_attributes(&mut self, attrs: &[ast::Attribute]) {
 550         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, true)
 551     }
 552
 553     fn print_inner_attributes_no_trailing_hardbreak(&mut self, attrs: &[ast::Attribute]) {
 554         self.print_either_attributes(attrs, ast::AttrStyle::Inner, false, false)
 555     }
 556
 557     fn print_outer_attributes(&mut self, attrs: &[ast::Attribute]) {
 558         self.print_either_attributes(attrs, ast::AttrStyle::Outer, false, true)
 559     }
 560
 561     fn print_inner_attributes_inline(&mut self, attrs: &[ast::Attribute]) {
 562         self.print_either_attributes(attrs, ast::AttrStyle::Inner, true, true)
 563     }
 564
 565     fn print_outer_attributes_inline(&mut self, attrs: &[ast::Attribute]) {
 566         self.print_either_attributes(attrs, ast::AttrStyle::Outer, true, true)
 567     }
 568
 569     fn print_either_attributes(
 570         &mut self,
 571         attrs: &[ast::Attribute],
 572         kind: ast::AttrStyle,
 573         is_inline: bool,
 574         trailing_hardbreak: bool,
 575     ) {
 576         let mut count = 0;
 577         for attr in attrs {
 578             if attr.style == kind {
 579                 self.print_attribute_inline(attr, is_inline);
 580                 if is_inline {
 581                     self.nbsp();
 582                 }
 583                 count += 1;
 584             }
 585         }
 586         if count > 0 && trailing_hardbreak && !is_inline {
 587             self.hardbreak_if_not_bol();
 588         }
 589     }
 590
 591     fn print_attribute(&mut self, attr: &ast::Attribute) {
 592         self.print_attribute_inline(attr, false)
 593     }
 594
 595     fn print_attribute_inline(&mut self, attr: &ast::Attribute, is_inline: bool) {
 596         if !is_inline {
 597             self.hardbreak_if_not_bol();
 598         }
 599         self.maybe_print_comment(attr.span.lo());
 600         match attr.kind {
 601             ast::AttrKind::Normal(ref item) => {
 602                 match attr.style {
 603                     ast::AttrStyle::Inner => self.word("#!["),
 604                     ast::AttrStyle::Outer => self.word("#["),
 605                 }
 606                 self.print_attr_item(&item, attr.span);
 607                 self.word("]");
 608             }
 609             ast::AttrKind::DocComment(comment) => {
 610                 self.word(comment.to_string());
 611                 self.hardbreak()
 612             }
 613         }
 614     }
 615
 616     fn print_attr_item(&mut self, item: &ast::AttrItem, span: Span) {
 617         self.ibox(0);
 618         match &item.args {
 619             MacArgs::Delimited(_, delim, tokens) => self.print_mac_common(
 620                 Some(MacHeader::Path(&item.path)),
 621                 false,
 622                 None,
 623                 delim.to_token(),
 624                 tokens.clone(),
 625                 true,
 626                 span,
 627             ),
 628             MacArgs::Empty | MacArgs::Eq(..) => {
 629                 self.print_path(&item.path, false, 0);
 630                 if let MacArgs::Eq(_, tokens) = &item.args {
 631                     self.space();
 632                     self.word_space("=");
 633                     self.print_tts(tokens.clone(), true);
 634                 }
 635             }
 636         }
 637         self.end();
 638     }
 639
 640     fn print_meta_list_item(&mut self, item: &ast::NestedMetaItem) {
 641         match item {
 642             ast::NestedMetaItem::MetaItem(ref mi) => self.print_meta_item(mi),
 643             ast::NestedMetaItem::Literal(ref lit) => self.print_literal(lit),
 644         }
 645     }
 646
 647     fn print_meta_item(&mut self, item: &ast::MetaItem) {
 648         self.ibox(INDENT_UNIT);
 649         match item.kind {
 650             ast::MetaItemKind::Word => self.print_path(&item.path, false, 0),
 651             ast::MetaItemKind::NameValue(ref value) => {
 652                 self.print_path(&item.path, false, 0);
 653                 self.space();
 654                 self.word_space("=");
 655                 self.print_literal(value);
 656             }
 657             ast::MetaItemKind::List(ref items) => {
 658                 self.print_path(&item.path, false, 0);
 659                 self.popen();
 660                 self.commasep(Consistent, &items[..], |s, i| s.print_meta_list_item(i));
 661                 self.pclose();
 662             }
 663         }
 664         self.end();
 665     }
 666
 667     /// This doesn't deserve to be called "pretty" printing, but it should be
 668     /// meaning-preserving. A quick hack that might help would be to look at the
 669     /// spans embedded in the TTs to decide where to put spaces and newlines.
 670     /// But it'd be better to parse these according to the grammar of the
 671     /// appropriate macro, transcribe back into the grammar we just parsed from,
 672     /// and then pretty-print the resulting AST nodes (so, e.g., we print
 673     /// expression arguments as expressions). It can be done! I think.
 674     fn print_tt(&mut self, tt: tokenstream::TokenTree, convert_dollar_crate: bool) {
 675         match tt {
 676             TokenTree::Token(ref token) => {
 677                 self.word(token_to_string_ext(&token, convert_dollar_crate));
 678                 match token.kind {
 679                     token::DocComment(..) => self.hardbreak(),
 680                     _ => {}
 681                 }
 682             }
 683             TokenTree::Delimited(dspan, delim, tts) => {
 684                 self.print_mac_common(
 685                     None,
 686                     false,
 687                     None,
 688                     delim,
 689                     tts,
 690                     convert_dollar_crate,
 691                     dspan.entire(),
 692                 );
 693             }
 694         }
 695     }
 696
 697     fn print_tts(&mut self, tts: tokenstream::TokenStream, convert_dollar_crate: bool) {
 698         for (i, tt) in tts.into_trees().enumerate() {
 699             if i != 0 && tt_prepend_space(&tt) {
 700                 self.space();
 701             }
 702             self.print_tt(tt, convert_dollar_crate);
 703         }
 704     }
 705
 706     fn print_mac_common(
 707         &mut self,
 708         header: Option<MacHeader<'_>>,
 709         has_bang: bool,
 710         ident: Option<ast::Ident>,
 711         delim: DelimToken,
 712         tts: TokenStream,
 713         convert_dollar_crate: bool,
 714         span: Span,
 715     ) {
 716         if delim == DelimToken::Brace {
 717             self.cbox(INDENT_UNIT);
 718         }
 719         match header {
 720             Some(MacHeader::Path(path)) => self.print_path(path, false, 0),
 721             Some(MacHeader::Keyword(kw)) => self.word(kw),
 722             None => {}
 723         }
 724         if has_bang {
 725             self.word("!");
 726         }
 727         if let Some(ident) = ident {
 728             self.nbsp();
 729             self.print_ident(ident);
 730         }
 731         match delim {
 732             DelimToken::Brace => {
 733                 if header.is_some() || has_bang || ident.is_some() {
 734                     self.nbsp();
 735                 }
 736                 self.word("{");
 737                 if !tts.is_empty() {
 738                     self.space();
 739                 }
 740             }
 741             _ => self.word(token_kind_to_string(&token::OpenDelim(delim))),
 742         }
 743         self.ibox(0);
 744         self.print_tts(tts, convert_dollar_crate);
 745         self.end();
 746         match delim {
 747             DelimToken::Brace => self.bclose(span),
 748             _ => self.word(token_kind_to_string(&token::CloseDelim(delim))),
 749         }
 750     }
 751
 752     fn print_path(&mut self, path: &ast::Path, colons_before_params: bool, depth: usize) {
 753         self.maybe_print_comment(path.span.lo());
 754
 755         for (i, segment) in path.segments[..path.segments.len() - depth].iter().enumerate() {
 756             if i > 0 {
 757                 self.word("::")
 758             }
 759             self.print_path_segment(segment, colons_before_params);
 760         }
 761     }
 762
 763     fn print_path_segment(&mut self, segment: &ast::PathSegment, colons_before_params: bool) {
 764         if segment.ident.name != kw::PathRoot {
 765             self.print_ident(segment.ident);
 766             if let Some(ref args) = segment.args {
 767                 self.print_generic_args(args, colons_before_params);
 768             }
 769         }
 770     }
 771
 772     fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) {
 773         let w = w.into();
 774         // Outer-box is consistent.
 775         self.cbox(INDENT_UNIT);
 776         // Head-box is inconsistent.
 777         self.ibox(w.len() + 1);
 778         // Keyword that starts the head.
 779         if !w.is_empty() {
 780             self.word_nbsp(w);
 781         }
 782     }
 783
 784     fn bopen(&mut self) {
 785         self.word("{");
 786         self.end(); // Close the head-box.
 787     }
 788
 789     fn bclose_maybe_open(&mut self, span: rustc_span::Span, close_box: bool) {
 790         self.maybe_print_comment(span.hi());
 791         self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
 792         self.word("}");
 793         if close_box {
 794             self.end(); // Close the outer-box.
 795         }
 796     }
 797
 798     fn bclose(&mut self, span: rustc_span::Span) {
 799         self.bclose_maybe_open(span, true)
 800     }
 801
 802     fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
 803         if !self.is_beginning_of_line() {
 804             self.break_offset(n, off)
 805         } else {
 806             if off != 0 && self.last_token().is_hardbreak_tok() {
 807                 // We do something pretty sketchy here: tuck the nonzero
 808                 // offset-adjustment we were going to deposit along with the
 809                 // break into the previous hardbreak.
 810                 self.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
 811             }
 812         }
 813     }
 814 }
 815
 816 impl<'a> PrintState<'a> for State<'a> {
 817     fn comments(&mut self) -> &mut Option<Comments<'a>> {
 818         &mut self.comments
 819     }
 820
 821     fn print_ident(&mut self, ident: ast::Ident) {
 822         self.s.word(ast_ident_to_string(ident, ident.is_raw_guess()));
 823         self.ann.post(self, AnnNode::Ident(&ident))
 824     }
 825
 826     fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool) {
 827         if colons_before_params {
 828             self.s.word("::")
 829         }
 830
 831         match *args {
 832             ast::GenericArgs::AngleBracketed(ref data) => {
 833                 self.s.word("<");
 834
 835                 self.commasep(Inconsistent, &data.args, |s, generic_arg| {
 836                     s.print_generic_arg(generic_arg)
 837                 });
 838
 839                 let mut comma = data.args.len() != 0;
 840
 841                 for constraint in data.constraints.iter() {
 842                     if comma {
 843                         self.word_space(",")
 844                     }
 845                     self.print_ident(constraint.ident);
 846                     self.s.space();
 847                     match constraint.kind {
 848                         ast::AssocTyConstraintKind::Equality { ref ty } => {
 849                             self.word_space("=");
 850                             self.print_type(ty);
 851                         }
 852                         ast::AssocTyConstraintKind::Bound { ref bounds } => {
 853                             self.print_type_bounds(":", &*bounds);
 854                         }
 855                     }
 856                     comma = true;
 857                 }
 858
 859                 self.s.word(">")
 860             }
 861
 862             ast::GenericArgs::Parenthesized(ref data) => {
 863                 self.s.word("(");
 864                 self.commasep(Inconsistent, &data.inputs, |s, ty| s.print_type(ty));
 865                 self.s.word(")");
 866                 self.print_fn_ret_ty(&data.output);
 867             }
 868         }
 869     }
 870 }
 871
 872 impl<'a> State<'a> {
 873     // Synthesizes a comment that was not textually present in the original source
 874     // file.
 875     pub fn synth_comment(&mut self, text: String) {
 876         self.s.word("/*");
 877         self.s.space();
 878         self.s.word(text);
 879         self.s.space();
 880         self.s.word("*/")
 881     }
 882
 883     crate fn commasep_cmnt<T, F, G>(&mut self, b: Breaks, elts: &[T], mut op: F, mut get_span: G)
 884     where
 885         F: FnMut(&mut State<'_>, &T),
 886         G: FnMut(&T) -> rustc_span::Span,
 887     {
 888         self.rbox(0, b);
 889         let len = elts.len();
 890         let mut i = 0;
 891         for elt in elts {
 892             self.maybe_print_comment(get_span(elt).hi());
 893             op(self, elt);
 894             i += 1;
 895             if i < len {
 896                 self.s.word(",");
 897                 self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()));
 898                 self.space_if_not_bol();
 899             }
 900         }
 901         self.end();
 902     }
 903
 904     crate fn commasep_exprs(&mut self, b: Breaks, exprs: &[P<ast::Expr>]) {
 905         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(e), |e| e.span)
 906     }
 907
 908     pub fn print_mod(&mut self, _mod: &ast::Mod, attrs: &[ast::Attribute]) {
 909         self.print_inner_attributes(attrs);
 910         for item in &_mod.items {
 911             self.print_item(item);
 912         }
 913     }
 914
 915     crate fn print_foreign_mod(&mut self, nmod: &ast::ForeignMod, attrs: &[ast::Attribute]) {
 916         self.print_inner_attributes(attrs);
 917         for item in &nmod.items {
 918             self.print_foreign_item(item);
 919         }
 920     }
 921
 922     pub fn print_opt_lifetime(&mut self, lifetime: &Option<ast::Lifetime>) {
 923         if let Some(lt) = *lifetime {
 924             self.print_lifetime(lt);
 925             self.nbsp();
 926         }
 927     }
 928
 929     crate fn print_generic_arg(&mut self, generic_arg: &GenericArg) {
 930         match generic_arg {
 931             GenericArg::Lifetime(lt) => self.print_lifetime(*lt),
 932             GenericArg::Type(ty) => self.print_type(ty),
 933             GenericArg::Const(ct) => self.print_expr(&ct.value),
 934         }
 935     }
 936
 937     pub fn print_type(&mut self, ty: &ast::Ty) {
 938         self.maybe_print_comment(ty.span.lo());
 939         self.ibox(0);
 940         match ty.kind {
 941             ast::TyKind::Slice(ref ty) => {
 942                 self.s.word("[");
 943                 self.print_type(ty);
 944                 self.s.word("]");
 945             }
 946             ast::TyKind::Ptr(ref mt) => {
 947                 self.s.word("*");
 948                 self.print_mt(mt, true);
 949             }
 950             ast::TyKind::Rptr(ref lifetime, ref mt) => {
 951                 self.s.word("&");
 952                 self.print_opt_lifetime(lifetime);
 953                 self.print_mt(mt, false);
 954             }
 955             ast::TyKind::Never => {
 956                 self.s.word("!");
 957             }
 958             ast::TyKind::Tup(ref elts) => {
 959                 self.popen();
 960                 self.commasep(Inconsistent, &elts[..], |s, ty| s.print_type(ty));
 961                 if elts.len() == 1 {
 962                     self.s.word(",");
 963                 }
 964                 self.pclose();
 965             }
 966             ast::TyKind::Paren(ref typ) => {
 967                 self.popen();
 968                 self.print_type(typ);
 969                 self.pclose();
 970             }
 971             ast::TyKind::BareFn(ref f) => {
 972                 self.print_ty_fn(f.ext, f.unsafety, &f.decl, None, &f.generic_params);
 973             }
 974             ast::TyKind::Path(None, ref path) => {
 975                 self.print_path(path, false, 0);
 976             }
 977             ast::TyKind::Path(Some(ref qself), ref path) => self.print_qpath(path, qself, false),
 978             ast::TyKind::TraitObject(ref bounds, syntax) => {
 979                 let prefix = if syntax == ast::TraitObjectSyntax::Dyn { "dyn" } else { "" };
 980                 self.print_type_bounds(prefix, &bounds[..]);
 981             }
 982             ast::TyKind::ImplTrait(_, ref bounds) => {
 983                 self.print_type_bounds("impl", &bounds[..]);
 984             }
 985             ast::TyKind::Array(ref ty, ref length) => {
 986                 self.s.word("[");
 987                 self.print_type(ty);
 988                 self.s.word("; ");
 989                 self.print_expr(&length.value);
 990                 self.s.word("]");
 991             }
 992             ast::TyKind::Typeof(ref e) => {
 993                 self.s.word("typeof(");
 994                 self.print_expr(&e.value);
 995                 self.s.word(")");
 996             }
 997             ast::TyKind::Infer => {
 998                 self.s.word("_");
 999             }
1000             ast::TyKind::Err => {
1001                 self.popen();
1002                 self.s.word("/*ERROR*/");
1003                 self.pclose();
1004             }
1005             ast::TyKind::ImplicitSelf => {
1006                 self.s.word("Self");
1007             }
1008             ast::TyKind::Mac(ref m) => {
1009                 self.print_mac(m);
1010             }
1011             ast::TyKind::CVarArgs => {
1012                 self.s.word("...");
1013             }
1014         }
1015         self.end();
1016     }
1017
1018     crate fn print_foreign_item(&mut self, item: &ast::ForeignItem) {
1019         self.hardbreak_if_not_bol();
1020         self.maybe_print_comment(item.span.lo());
1021         self.print_outer_attributes(&item.attrs);
1022         match &item.kind {
1023             ast::ForeignItemKind::Fn(sig, gen, body) => {
1024                 self.print_fn_full(sig, item.ident, gen, &item.vis, body.as_deref(), &item.attrs);
1025             }
1026             ast::ForeignItemKind::Static(t, m) => {
1027                 self.head(visibility_qualified(&item.vis, "static"));
1028                 if *m == ast::Mutability::Mut {
1029                     self.word_space("mut");
1030                 }
1031                 self.print_ident(item.ident);
1032                 self.word_space(":");
1033                 self.print_type(t);
1034                 self.s.word(";");
1035                 self.end(); // end the head-ibox
1036                 self.end(); // end the outer cbox
1037             }
1038             ast::ForeignItemKind::TyAlias(generics, bounds, ty) => {
1039                 self.print_associated_type(item.ident, generics, bounds, ty.as_deref());
1040             }
1041             ast::ForeignItemKind::Macro(m) => {
1042                 self.print_mac(m);
1043                 if m.args.need_semicolon() {
1044                     self.s.word(";");
1045                 }
1046             }
1047         }
1048     }
1049
1050     fn print_associated_const(
1051         &mut self,
1052         ident: ast::Ident,
1053         ty: &ast::Ty,
1054         default: Option<&ast::Expr>,
1055         vis: &ast::Visibility,
1056     ) {
1057         self.s.word(visibility_qualified(vis, ""));
1058         self.word_space("const");
1059         self.print_ident(ident);
1060         self.word_space(":");
1061         self.print_type(ty);
1062         if let Some(expr) = default {
1063             self.s.space();
1064             self.word_space("=");
1065             self.print_expr(expr);
1066         }
1067         self.s.word(";")
1068     }
1069
1070     fn print_associated_type(
1071         &mut self,
1072         ident: ast::Ident,
1073         generics: &ast::Generics,
1074         bounds: &ast::GenericBounds,
1075         ty: Option<&ast::Ty>,
1076     ) {
1077         self.word_space("type");
1078         self.print_ident(ident);
1079         self.print_generic_params(&generics.params);
1080         self.print_type_bounds(":", bounds);
1081         self.print_where_clause(&generics.where_clause);
1082         if let Some(ty) = ty {
1083             self.s.space();
1084             self.word_space("=");
1085             self.print_type(ty);
1086         }
1087         self.s.word(";")
1088     }
1089
1090     /// Pretty-prints an item.
1091     crate fn print_item(&mut self, item: &ast::Item) {
1092         self.hardbreak_if_not_bol();
1093         self.maybe_print_comment(item.span.lo());
1094         self.print_outer_attributes(&item.attrs);
1095         self.ann.pre(self, AnnNode::Item(item));
1096         match item.kind {
1097             ast::ItemKind::ExternCrate(orig_name) => {
1098                 self.head(visibility_qualified(&item.vis, "extern crate"));
1099                 if let Some(orig_name) = orig_name {
1100                     self.print_name(orig_name);
1101                     self.s.space();
1102                     self.s.word("as");
1103                     self.s.space();
1104                 }
1105                 self.print_ident(item.ident);
1106                 self.s.word(";");
1107                 self.end(); // end inner head-block
1108                 self.end(); // end outer head-block
1109             }
1110             ast::ItemKind::Use(ref tree) => {
1111                 self.head(visibility_qualified(&item.vis, "use"));
1112                 self.print_use_tree(tree);
1113                 self.s.word(";");
1114                 self.end(); // end inner head-block
1115                 self.end(); // end outer head-block
1116             }
1117             ast::ItemKind::Static(ref ty, m, ref expr) => {
1118                 self.head(visibility_qualified(&item.vis, "static"));
1119                 if m == ast::Mutability::Mut {
1120                     self.word_space("mut");
1121                 }
1122                 self.print_ident(item.ident);
1123                 self.word_space(":");
1124                 self.print_type(ty);
1125                 self.s.space();
1126                 self.end(); // end the head-ibox
1127                 if let Some(expr) = expr {
1128                     self.word_space("=");
1129                     self.print_expr(expr);
1130                 }
1131                 self.s.word(";");
1132                 self.end(); // end the outer cbox
1133             }
1134             ast::ItemKind::Const(ref ty, ref expr) => {
1135                 self.head(visibility_qualified(&item.vis, "const"));
1136                 self.print_ident(item.ident);
1137                 self.word_space(":");
1138                 self.print_type(ty);
1139                 self.s.space();
1140                 self.end(); // end the head-ibox
1141                 if let Some(expr) = expr {
1142                     self.word_space("=");
1143                     self.print_expr(expr);
1144                 }
1145                 self.s.word(";");
1146                 self.end(); // end the outer cbox
1147             }
1148             ast::ItemKind::Fn(ref sig, ref gen, ref body) => {
1149                 self.print_fn_full(sig, item.ident, gen, &item.vis, body.as_deref(), &item.attrs);
1150             }
1151             ast::ItemKind::Mod(ref _mod) => {
1152                 self.head(visibility_qualified(&item.vis, "mod"));
1153                 self.print_ident(item.ident);
1154
1155                 if _mod.inline || self.is_expanded {
1156                     self.nbsp();
1157                     self.bopen();
1158                     self.print_mod(_mod, &item.attrs);
1159                     self.bclose(item.span);
1160                 } else {
1161                     self.s.word(";");
1162                     self.end(); // end inner head-block
1163                     self.end(); // end outer head-block
1164                 }
1165             }
1166             ast::ItemKind::ForeignMod(ref nmod) => {
1167                 self.head("extern");
1168                 if let Some(abi) = nmod.abi {
1169                     self.print_literal(&abi.as_lit());
1170                     self.nbsp();
1171                 }
1172                 self.bopen();
1173                 self.print_foreign_mod(nmod, &item.attrs);
1174                 self.bclose(item.span);
1175             }
1176             ast::ItemKind::GlobalAsm(ref ga) => {
1177                 self.head(visibility_qualified(&item.vis, "global_asm!"));
1178                 self.s.word(ga.asm.to_string());
1179                 self.end();
1180             }
1181             ast::ItemKind::TyAlias(ref ty, ref generics) => {
1182                 self.head(visibility_qualified(&item.vis, "type"));
1183                 self.print_ident(item.ident);
1184                 self.print_generic_params(&generics.params);
1185                 self.end(); // end the inner ibox
1186
1187                 self.print_where_clause(&generics.where_clause);
1188                 self.s.space();
1189                 self.word_space("=");
1190                 self.print_type(ty);
1191                 self.s.word(";");
1192                 self.end(); // end the outer ibox
1193             }
1194             ast::ItemKind::Enum(ref enum_definition, ref params) => {
1195                 self.print_enum_def(enum_definition, params, item.ident, item.span, &item.vis);
1196             }
1197             ast::ItemKind::Struct(ref struct_def, ref generics) => {
1198                 self.head(visibility_qualified(&item.vis, "struct"));
1199                 self.print_struct(struct_def, generics, item.ident, item.span, true);
1200             }
1201             ast::ItemKind::Union(ref struct_def, ref generics) => {
1202                 self.head(visibility_qualified(&item.vis, "union"));
1203                 self.print_struct(struct_def, generics, item.ident, item.span, true);
1204             }
1205             ast::ItemKind::Impl {
1206                 unsafety,
1207                 polarity,
1208                 defaultness,
1209                 constness,
1210                 ref generics,
1211                 ref of_trait,
1212                 ref self_ty,
1213                 ref items,
1214             } => {
1215                 self.head("");
1216                 self.print_visibility(&item.vis);
1217                 self.print_defaultness(defaultness);
1218                 self.print_unsafety(unsafety);
1219                 self.word_nbsp("impl");
1220                 self.print_constness(constness);
1221
1222                 if !generics.params.is_empty() {
1223                     self.print_generic_params(&generics.params);
1224                     self.s.space();
1225                 }
1226
1227                 if polarity == ast::ImplPolarity::Negative {
1228                     self.s.word("!");
1229                 }
1230
1231                 if let Some(ref t) = *of_trait {
1232                     self.print_trait_ref(t);
1233                     self.s.space();
1234                     self.word_space("for");
1235                 }
1236
1237                 self.print_type(self_ty);
1238                 self.print_where_clause(&generics.where_clause);
1239
1240                 self.s.space();
1241                 self.bopen();
1242                 self.print_inner_attributes(&item.attrs);
1243                 for impl_item in items {
1244                     self.print_assoc_item(impl_item);
1245                 }
1246                 self.bclose(item.span);
1247             }
1248             ast::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref trait_items) => {
1249                 self.head("");
1250                 self.print_visibility(&item.vis);
1251                 self.print_unsafety(unsafety);
1252                 self.print_is_auto(is_auto);
1253                 self.word_nbsp("trait");
1254                 self.print_ident(item.ident);
1255                 self.print_generic_params(&generics.params);
1256                 let mut real_bounds = Vec::with_capacity(bounds.len());
1257                 for b in bounds.iter() {
1258                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1259                         self.s.space();
1260                         self.word_space("for ?");
1261                         self.print_trait_ref(&ptr.trait_ref);
1262                     } else {
1263                         real_bounds.push(b.clone());
1264                     }
1265                 }
1266                 self.print_type_bounds(":", &real_bounds[..]);
1267                 self.print_where_clause(&generics.where_clause);
1268                 self.s.word(" ");
1269                 self.bopen();
1270                 self.print_inner_attributes(&item.attrs);
1271                 for trait_item in trait_items {
1272                     self.print_assoc_item(trait_item);
1273                 }
1274                 self.bclose(item.span);
1275             }
1276             ast::ItemKind::TraitAlias(ref generics, ref bounds) => {
1277                 self.head("");
1278                 self.print_visibility(&item.vis);
1279                 self.word_nbsp("trait");
1280                 self.print_ident(item.ident);
1281                 self.print_generic_params(&generics.params);
1282                 let mut real_bounds = Vec::with_capacity(bounds.len());
1283                 // FIXME(durka) this seems to be some quite outdated syntax
1284                 for b in bounds.iter() {
1285                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1286                         self.s.space();
1287                         self.word_space("for ?");
1288                         self.print_trait_ref(&ptr.trait_ref);
1289                     } else {
1290                         real_bounds.push(b.clone());
1291                     }
1292                 }
1293                 self.nbsp();
1294                 self.print_type_bounds("=", &real_bounds[..]);
1295                 self.print_where_clause(&generics.where_clause);
1296                 self.s.word(";");
1297             }
1298             ast::ItemKind::Mac(ref mac) => {
1299                 self.print_mac(mac);
1300                 if mac.args.need_semicolon() {
1301                     self.s.word(";");
1302                 }
1303             }
1304             ast::ItemKind::MacroDef(ref macro_def) => {
1305                 let (kw, has_bang) = if macro_def.legacy {
1306                     ("macro_rules", true)
1307                 } else {
1308                     self.print_visibility(&item.vis);
1309                     ("macro", false)
1310                 };
1311                 self.print_mac_common(
1312                     Some(MacHeader::Keyword(kw)),
1313                     has_bang,
1314                     Some(item.ident),
1315                     macro_def.body.delim(),
1316                     macro_def.body.inner_tokens(),
1317                     true,
1318                     item.span,
1319                 );
1320             }
1321         }
1322         self.ann.post(self, AnnNode::Item(item))
1323     }
1324
1325     fn print_trait_ref(&mut self, t: &ast::TraitRef) {
1326         self.print_path(&t.path, false, 0)
1327     }
1328
1329     fn print_formal_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
1330         if !generic_params.is_empty() {
1331             self.s.word("for");
1332             self.print_generic_params(generic_params);
1333             self.nbsp();
1334         }
1335     }
1336
1337     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) {
1338         self.print_formal_generic_params(&t.bound_generic_params);
1339         self.print_trait_ref(&t.trait_ref)
1340     }
1341
1342     crate fn print_enum_def(
1343         &mut self,
1344         enum_definition: &ast::EnumDef,
1345         generics: &ast::Generics,
1346         ident: ast::Ident,
1347         span: rustc_span::Span,
1348         visibility: &ast::Visibility,
1349     ) {
1350         self.head(visibility_qualified(visibility, "enum"));
1351         self.print_ident(ident);
1352         self.print_generic_params(&generics.params);
1353         self.print_where_clause(&generics.where_clause);
1354         self.s.space();
1355         self.print_variants(&enum_definition.variants, span)
1356     }
1357
1358     crate fn print_variants(&mut self, variants: &[ast::Variant], span: rustc_span::Span) {
1359         self.bopen();
1360         for v in variants {
1361             self.space_if_not_bol();
1362             self.maybe_print_comment(v.span.lo());
1363             self.print_outer_attributes(&v.attrs);
1364             self.ibox(INDENT_UNIT);
1365             self.print_variant(v);
1366             self.s.word(",");
1367             self.end();
1368             self.maybe_print_trailing_comment(v.span, None);
1369         }
1370         self.bclose(span)
1371     }
1372
1373     crate fn print_visibility(&mut self, vis: &ast::Visibility) {
1374         match vis.node {
1375             ast::VisibilityKind::Public => self.word_nbsp("pub"),
1376             ast::VisibilityKind::Crate(sugar) => match sugar {
1377                 ast::CrateSugar::PubCrate => self.word_nbsp("pub(crate)"),
1378                 ast::CrateSugar::JustCrate => self.word_nbsp("crate"),
1379             },
1380             ast::VisibilityKind::Restricted { ref path, .. } => {
1381                 let path = to_string(|s| s.print_path(path, false, 0));
1382                 if path == "self" || path == "super" {
1383                     self.word_nbsp(format!("pub({})", path))
1384                 } else {
1385                     self.word_nbsp(format!("pub(in {})", path))
1386                 }
1387             }
1388             ast::VisibilityKind::Inherited => {}
1389         }
1390     }
1391
1392     crate fn print_defaultness(&mut self, defaultness: ast::Defaultness) {
1393         if let ast::Defaultness::Default = defaultness {
1394             self.word_nbsp("default");
1395         }
1396     }
1397
1398     crate fn print_struct(
1399         &mut self,
1400         struct_def: &ast::VariantData,
1401         generics: &ast::Generics,
1402         ident: ast::Ident,
1403         span: rustc_span::Span,
1404         print_finalizer: bool,
1405     ) {
1406         self.print_ident(ident);
1407         self.print_generic_params(&generics.params);
1408         match struct_def {
1409             ast::VariantData::Tuple(..) | ast::VariantData::Unit(..) => {
1410                 if let ast::VariantData::Tuple(..) = struct_def {
1411                     self.popen();
1412                     self.commasep(Inconsistent, struct_def.fields(), |s, field| {
1413                         s.maybe_print_comment(field.span.lo());
1414                         s.print_outer_attributes(&field.attrs);
1415                         s.print_visibility(&field.vis);
1416                         s.print_type(&field.ty)
1417                     });
1418                     self.pclose();
1419                 }
1420                 self.print_where_clause(&generics.where_clause);
1421                 if print_finalizer {
1422                     self.s.word(";");
1423                 }
1424                 self.end();
1425                 self.end(); // Close the outer-box.
1426             }
1427             ast::VariantData::Struct(..) => {
1428                 self.print_where_clause(&generics.where_clause);
1429                 self.nbsp();
1430                 self.bopen();
1431                 self.hardbreak_if_not_bol();
1432
1433                 for field in struct_def.fields() {
1434                     self.hardbreak_if_not_bol();
1435                     self.maybe_print_comment(field.span.lo());
1436                     self.print_outer_attributes(&field.attrs);
1437                     self.print_visibility(&field.vis);
1438                     self.print_ident(field.ident.unwrap());
1439                     self.word_nbsp(":");
1440                     self.print_type(&field.ty);
1441                     self.s.word(",");
1442                 }
1443
1444                 self.bclose(span)
1445             }
1446         }
1447     }
1448
1449     crate fn print_variant(&mut self, v: &ast::Variant) {
1450         self.head("");
1451         self.print_visibility(&v.vis);
1452         let generics = ast::Generics::default();
1453         self.print_struct(&v.data, &generics, v.ident, v.span, false);
1454         match v.disr_expr {
1455             Some(ref d) => {
1456                 self.s.space();
1457                 self.word_space("=");
1458                 self.print_expr(&d.value)
1459             }
1460             _ => {}
1461         }
1462     }
1463
1464     crate fn print_assoc_item(&mut self, item: &ast::AssocItem) {
1465         self.ann.pre(self, AnnNode::SubItem(item.id));
1466         self.hardbreak_if_not_bol();
1467         self.maybe_print_comment(item.span.lo());
1468         self.print_outer_attributes(&item.attrs);
1469         self.print_defaultness(item.defaultness);
1470         match &item.kind {
1471             ast::AssocItemKind::Const(ty, expr) => {
1472                 self.print_associated_const(item.ident, ty, expr.as_deref(), &item.vis);
1473             }
1474             ast::AssocItemKind::Fn(sig, generics, body) => {
1475                 let body = body.as_deref();
1476                 self.print_fn_full(sig, item.ident, generics, &item.vis, body, &item.attrs);
1477             }
1478             ast::AssocItemKind::TyAlias(generics, bounds, ty) => {
1479                 self.print_associated_type(item.ident, generics, bounds, ty.as_deref());
1480             }
1481             ast::AssocItemKind::Macro(mac) => {
1482                 self.print_mac(mac);
1483                 if mac.args.need_semicolon() {
1484                     self.s.word(";");
1485                 }
1486             }
1487         }
1488         self.ann.post(self, AnnNode::SubItem(item.id))
1489     }
1490
1491     crate fn print_stmt(&mut self, st: &ast::Stmt) {
1492         self.maybe_print_comment(st.span.lo());
1493         match st.kind {
1494             ast::StmtKind::Local(ref loc) => {
1495                 self.print_outer_attributes(&loc.attrs);
1496                 self.space_if_not_bol();
1497                 self.ibox(INDENT_UNIT);
1498                 self.word_nbsp("let");
1499
1500                 self.ibox(INDENT_UNIT);
1501                 self.print_local_decl(loc);
1502                 self.end();
1503                 if let Some(ref init) = loc.init {
1504                     self.nbsp();
1505                     self.word_space("=");
1506                     self.print_expr(init);
1507                 }
1508                 self.s.word(";");
1509                 self.end();
1510             }
1511             ast::StmtKind::Item(ref item) => self.print_item(item),
1512             ast::StmtKind::Expr(ref expr) => {
1513                 self.space_if_not_bol();
1514                 self.print_expr_outer_attr_style(expr, false);
1515                 if classify::expr_requires_semi_to_be_stmt(expr) {
1516                     self.s.word(";");
1517                 }
1518             }
1519             ast::StmtKind::Semi(ref expr) => {
1520                 match expr.kind {
1521                     // Filter out empty `Tup` exprs created for the `redundant_semicolon`
1522                     // lint, as they shouldn't be visible and interact poorly
1523                     // with proc macros.
1524                     ast::ExprKind::Tup(ref exprs) if exprs.is_empty() && expr.attrs.is_empty() => {
1525                         ()
1526                     }
1527                     _ => {
1528                         self.space_if_not_bol();
1529                         self.print_expr_outer_attr_style(expr, false);
1530                         self.s.word(";");
1531                     }
1532                 }
1533             }
1534             ast::StmtKind::Mac(ref mac) => {
1535                 let (ref mac, style, ref attrs) = **mac;
1536                 self.space_if_not_bol();
1537                 self.print_outer_attributes(attrs);
1538                 self.print_mac(mac);
1539                 if style == ast::MacStmtStyle::Semicolon {
1540                     self.s.word(";");
1541                 }
1542             }
1543         }
1544         self.maybe_print_trailing_comment(st.span, None)
1545     }
1546
1547     crate fn print_block(&mut self, blk: &ast::Block) {
1548         self.print_block_with_attrs(blk, &[])
1549     }
1550
1551     crate fn print_block_unclosed_indent(&mut self, blk: &ast::Block) {
1552         self.print_block_maybe_unclosed(blk, &[], false)
1553     }
1554
1555     crate fn print_block_with_attrs(&mut self, blk: &ast::Block, attrs: &[ast::Attribute]) {
1556         self.print_block_maybe_unclosed(blk, attrs, true)
1557     }
1558
1559     crate fn print_block_maybe_unclosed(
1560         &mut self,
1561         blk: &ast::Block,
1562         attrs: &[ast::Attribute],
1563         close_box: bool,
1564     ) {
1565         match blk.rules {
1566             BlockCheckMode::Unsafe(..) => self.word_space("unsafe"),
1567             BlockCheckMode::Default => (),
1568         }
1569         self.maybe_print_comment(blk.span.lo());
1570         self.ann.pre(self, AnnNode::Block(blk));
1571         self.bopen();
1572
1573         self.print_inner_attributes(attrs);
1574
1575         for (i, st) in blk.stmts.iter().enumerate() {
1576             match st.kind {
1577                 ast::StmtKind::Expr(ref expr) if i == blk.stmts.len() - 1 => {
1578                     self.maybe_print_comment(st.span.lo());
1579                     self.space_if_not_bol();
1580                     self.print_expr_outer_attr_style(expr, false);
1581                     self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
1582                 }
1583                 _ => self.print_stmt(st),
1584             }
1585         }
1586
1587         self.bclose_maybe_open(blk.span, close_box);
1588         self.ann.post(self, AnnNode::Block(blk))
1589     }
1590
1591     /// Print a `let pat = scrutinee` expression.
1592     crate fn print_let(&mut self, pat: &ast::Pat, scrutinee: &ast::Expr) {
1593         self.s.word("let ");
1594
1595         self.print_pat(pat);
1596         self.s.space();
1597
1598         self.word_space("=");
1599         self.print_expr_cond_paren(
1600             scrutinee,
1601             Self::cond_needs_par(scrutinee)
1602                 || parser::needs_par_as_let_scrutinee(scrutinee.precedence().order()),
1603         )
1604     }
1605
1606     fn print_else(&mut self, els: Option<&ast::Expr>) {
1607         if let Some(_else) = els {
1608             match _else.kind {
1609                 // Another `else if` block.
1610                 ast::ExprKind::If(ref i, ref then, ref e) => {
1611                     self.cbox(INDENT_UNIT - 1);
1612                     self.ibox(0);
1613                     self.s.word(" else if ");
1614                     self.print_expr_as_cond(i);
1615                     self.s.space();
1616                     self.print_block(then);
1617                     self.print_else(e.as_deref())
1618                 }
1619                 // Final `else` block.
1620                 ast::ExprKind::Block(ref b, _) => {
1621                     self.cbox(INDENT_UNIT - 1);
1622                     self.ibox(0);
1623                     self.s.word(" else ");
1624                     self.print_block(b)
1625                 }
1626                 // Constraints would be great here!
1627                 _ => {
1628                     panic!("print_if saw if with weird alternative");
1629                 }
1630             }
1631         }
1632     }
1633
1634     crate fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block, elseopt: Option<&ast::Expr>) {
1635         self.head("if");
1636
1637         self.print_expr_as_cond(test);
1638         self.s.space();
1639
1640         self.print_block(blk);
1641         self.print_else(elseopt)
1642     }
1643
1644     crate fn print_mac(&mut self, m: &ast::Mac) {
1645         self.print_mac_common(
1646             Some(MacHeader::Path(&m.path)),
1647             true,
1648             None,
1649             m.args.delim(),
1650             m.args.inner_tokens(),
1651             true,
1652             m.span(),
1653         );
1654     }
1655
1656     fn print_call_post(&mut self, args: &[P<ast::Expr>]) {
1657         self.popen();
1658         self.commasep_exprs(Inconsistent, args);
1659         self.pclose()
1660     }
1661
1662     crate fn print_expr_maybe_paren(&mut self, expr: &ast::Expr, prec: i8) {
1663         self.print_expr_cond_paren(expr, expr.precedence().order() < prec)
1664     }
1665
1666     /// Prints an expr using syntax that's acceptable in a condition position, such as the `cond` in
1667     /// `if cond { ... }`.
1668     crate fn print_expr_as_cond(&mut self, expr: &ast::Expr) {
1669         self.print_expr_cond_paren(expr, Self::cond_needs_par(expr))
1670     }
1671
1672     /// Does `expr` need parenthesis when printed in a condition position?
1673     fn cond_needs_par(expr: &ast::Expr) -> bool {
1674         match expr.kind {
1675             // These cases need parens due to the parse error observed in #26461: `if return {}`
1676             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1677             ast::ExprKind::Closure(..) | ast::ExprKind::Ret(..) | ast::ExprKind::Break(..) => true,
1678
1679             _ => parser::contains_exterior_struct_lit(expr),
1680         }
1681     }
1682
1683     /// Prints `expr` or `(expr)` when `needs_par` holds.
1684     fn print_expr_cond_paren(&mut self, expr: &ast::Expr, needs_par: bool) {
1685         if needs_par {
1686             self.popen();
1687         }
1688         self.print_expr(expr);
1689         if needs_par {
1690             self.pclose();
1691         }
1692     }
1693
1694     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>], attrs: &[Attribute]) {
1695         self.ibox(INDENT_UNIT);
1696         self.s.word("[");
1697         self.print_inner_attributes_inline(attrs);
1698         self.commasep_exprs(Inconsistent, &exprs[..]);
1699         self.s.word("]");
1700         self.end();
1701     }
1702
1703     fn print_expr_repeat(
1704         &mut self,
1705         element: &ast::Expr,
1706         count: &ast::AnonConst,
1707         attrs: &[Attribute],
1708     ) {
1709         self.ibox(INDENT_UNIT);
1710         self.s.word("[");
1711         self.print_inner_attributes_inline(attrs);
1712         self.print_expr(element);
1713         self.word_space(";");
1714         self.print_expr(&count.value);
1715         self.s.word("]");
1716         self.end();
1717     }
1718
1719     fn print_expr_struct(
1720         &mut self,
1721         path: &ast::Path,
1722         fields: &[ast::Field],
1723         wth: &Option<P<ast::Expr>>,
1724         attrs: &[Attribute],
1725     ) {
1726         self.print_path(path, true, 0);
1727         self.s.word("{");
1728         self.print_inner_attributes_inline(attrs);
1729         self.commasep_cmnt(
1730             Consistent,
1731             &fields[..],
1732             |s, field| {
1733                 s.print_outer_attributes(&field.attrs);
1734                 s.ibox(INDENT_UNIT);
1735                 if !field.is_shorthand {
1736                     s.print_ident(field.ident);
1737                     s.word_space(":");
1738                 }
1739                 s.print_expr(&field.expr);
1740                 s.end();
1741             },
1742             |f| f.span,
1743         );
1744         match *wth {
1745             Some(ref expr) => {
1746                 self.ibox(INDENT_UNIT);
1747                 if !fields.is_empty() {
1748                     self.s.word(",");
1749                     self.s.space();
1750                 }
1751                 self.s.word("..");
1752                 self.print_expr(expr);
1753                 self.end();
1754             }
1755             _ => {
1756                 if !fields.is_empty() {
1757                     self.s.word(",")
1758                 }
1759             }
1760         }
1761         self.s.word("}");
1762     }
1763
1764     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>], attrs: &[Attribute]) {
1765         self.popen();
1766         self.print_inner_attributes_inline(attrs);
1767         self.commasep_exprs(Inconsistent, &exprs[..]);
1768         if exprs.len() == 1 {
1769             self.s.word(",");
1770         }
1771         self.pclose()
1772     }
1773
1774     fn print_expr_call(&mut self, func: &ast::Expr, args: &[P<ast::Expr>]) {
1775         let prec = match func.kind {
1776             ast::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1777             _ => parser::PREC_POSTFIX,
1778         };
1779
1780         self.print_expr_maybe_paren(func, prec);
1781         self.print_call_post(args)
1782     }
1783
1784     fn print_expr_method_call(&mut self, segment: &ast::PathSegment, args: &[P<ast::Expr>]) {
1785         let base_args = &args[1..];
1786         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
1787         self.s.word(".");
1788         self.print_ident(segment.ident);
1789         if let Some(ref args) = segment.args {
1790             self.print_generic_args(args, true);
1791         }
1792         self.print_call_post(base_args)
1793     }
1794
1795     fn print_expr_binary(&mut self, op: ast::BinOp, lhs: &ast::Expr, rhs: &ast::Expr) {
1796         let assoc_op = AssocOp::from_ast_binop(op.node);
1797         let prec = assoc_op.precedence() as i8;
1798         let fixity = assoc_op.fixity();
1799
1800         let (left_prec, right_prec) = match fixity {
1801             Fixity::Left => (prec, prec + 1),
1802             Fixity::Right => (prec + 1, prec),
1803             Fixity::None => (prec + 1, prec + 1),
1804         };
1805
1806         let left_prec = match (&lhs.kind, op.node) {
1807             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1808             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1809             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1810             (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Lt)
1811             | (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Shl) => parser::PREC_FORCE_PAREN,
1812             // We are given `(let _ = a) OP b`.
1813             //
1814             // - When `OP <= LAnd` we should print `let _ = a OP b` to avoid redundant parens
1815             //   as the parser will interpret this as `(let _ = a) OP b`.
1816             //
1817             // - Otherwise, e.g. when we have `(let a = b) < c` in AST,
1818             //   parens are required since the parser would interpret `let a = b < c` as
1819             //   `let a = (b < c)`. To achieve this, we force parens.
1820             (&ast::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(prec) => {
1821                 parser::PREC_FORCE_PAREN
1822             }
1823             _ => left_prec,
1824         };
1825
1826         self.print_expr_maybe_paren(lhs, left_prec);
1827         self.s.space();
1828         self.word_space(op.node.to_string());
1829         self.print_expr_maybe_paren(rhs, right_prec)
1830     }
1831
1832     fn print_expr_unary(&mut self, op: ast::UnOp, expr: &ast::Expr) {
1833         self.s.word(ast::UnOp::to_string(op));
1834         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1835     }
1836
1837     fn print_expr_addr_of(
1838         &mut self,
1839         kind: ast::BorrowKind,
1840         mutability: ast::Mutability,
1841         expr: &ast::Expr,
1842     ) {
1843         self.s.word("&");
1844         match kind {
1845             ast::BorrowKind::Ref => self.print_mutability(mutability, false),
1846             ast::BorrowKind::Raw => {
1847                 self.word_nbsp("raw");
1848                 self.print_mutability(mutability, true);
1849             }
1850         }
1851         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1852     }
1853
1854     pub fn print_expr(&mut self, expr: &ast::Expr) {
1855         self.print_expr_outer_attr_style(expr, true)
1856     }
1857
1858     fn print_expr_outer_attr_style(&mut self, expr: &ast::Expr, is_inline: bool) {
1859         self.maybe_print_comment(expr.span.lo());
1860
1861         let attrs = &expr.attrs;
1862         if is_inline {
1863             self.print_outer_attributes_inline(attrs);
1864         } else {
1865             self.print_outer_attributes(attrs);
1866         }
1867
1868         self.ibox(INDENT_UNIT);
1869         self.ann.pre(self, AnnNode::Expr(expr));
1870         match expr.kind {
1871             ast::ExprKind::Box(ref expr) => {
1872                 self.word_space("box");
1873                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX);
1874             }
1875             ast::ExprKind::Array(ref exprs) => {
1876                 self.print_expr_vec(&exprs[..], attrs);
1877             }
1878             ast::ExprKind::Repeat(ref element, ref count) => {
1879                 self.print_expr_repeat(element, count, attrs);
1880             }
1881             ast::ExprKind::Struct(ref path, ref fields, ref wth) => {
1882                 self.print_expr_struct(path, &fields[..], wth, attrs);
1883             }
1884             ast::ExprKind::Tup(ref exprs) => {
1885                 self.print_expr_tup(&exprs[..], attrs);
1886             }
1887             ast::ExprKind::Call(ref func, ref args) => {
1888                 self.print_expr_call(func, &args[..]);
1889             }
1890             ast::ExprKind::MethodCall(ref segment, ref args) => {
1891                 self.print_expr_method_call(segment, &args[..]);
1892             }
1893             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
1894                 self.print_expr_binary(op, lhs, rhs);
1895             }
1896             ast::ExprKind::Unary(op, ref expr) => {
1897                 self.print_expr_unary(op, expr);
1898             }
1899             ast::ExprKind::AddrOf(k, m, ref expr) => {
1900                 self.print_expr_addr_of(k, m, expr);
1901             }
1902             ast::ExprKind::Lit(ref lit) => {
1903                 self.print_literal(lit);
1904             }
1905             ast::ExprKind::Cast(ref expr, ref ty) => {
1906                 let prec = AssocOp::As.precedence() as i8;
1907                 self.print_expr_maybe_paren(expr, prec);
1908                 self.s.space();
1909                 self.word_space("as");
1910                 self.print_type(ty);
1911             }
1912             ast::ExprKind::Type(ref expr, ref ty) => {
1913                 let prec = AssocOp::Colon.precedence() as i8;
1914                 self.print_expr_maybe_paren(expr, prec);
1915                 self.word_space(":");
1916                 self.print_type(ty);
1917             }
1918             ast::ExprKind::Let(ref pat, ref scrutinee) => {
1919                 self.print_let(pat, scrutinee);
1920             }
1921             ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
1922                 self.print_if(test, blk, elseopt.as_deref())
1923             }
1924             ast::ExprKind::While(ref test, ref blk, opt_label) => {
1925                 if let Some(label) = opt_label {
1926                     self.print_ident(label.ident);
1927                     self.word_space(":");
1928                 }
1929                 self.head("while");
1930                 self.print_expr_as_cond(test);
1931                 self.s.space();
1932                 self.print_block_with_attrs(blk, attrs);
1933             }
1934             ast::ExprKind::ForLoop(ref pat, ref iter, ref blk, opt_label) => {
1935                 if let Some(label) = opt_label {
1936                     self.print_ident(label.ident);
1937                     self.word_space(":");
1938                 }
1939                 self.head("for");
1940                 self.print_pat(pat);
1941                 self.s.space();
1942                 self.word_space("in");
1943                 self.print_expr_as_cond(iter);
1944                 self.s.space();
1945                 self.print_block_with_attrs(blk, attrs);
1946             }
1947             ast::ExprKind::Loop(ref blk, opt_label) => {
1948                 if let Some(label) = opt_label {
1949                     self.print_ident(label.ident);
1950                     self.word_space(":");
1951                 }
1952                 self.head("loop");
1953                 self.s.space();
1954                 self.print_block_with_attrs(blk, attrs);
1955             }
1956             ast::ExprKind::Match(ref expr, ref arms) => {
1957                 self.cbox(INDENT_UNIT);
1958                 self.ibox(INDENT_UNIT);
1959                 self.word_nbsp("match");
1960                 self.print_expr_as_cond(expr);
1961                 self.s.space();
1962                 self.bopen();
1963                 self.print_inner_attributes_no_trailing_hardbreak(attrs);
1964                 for arm in arms {
1965                     self.print_arm(arm);
1966                 }
1967                 self.bclose(expr.span);
1968             }
1969             ast::ExprKind::Closure(
1970                 capture_clause,
1971                 asyncness,
1972                 movability,
1973                 ref decl,
1974                 ref body,
1975                 _,
1976             ) => {
1977                 self.print_movability(movability);
1978                 self.print_asyncness(asyncness);
1979                 self.print_capture_clause(capture_clause);
1980
1981                 self.print_fn_params_and_ret(decl, true);
1982                 self.s.space();
1983                 self.print_expr(body);
1984                 self.end(); // need to close a box
1985
1986                 // a box will be closed by print_expr, but we didn't want an overall
1987                 // wrapper so we closed the corresponding opening. so create an
1988                 // empty box to satisfy the close.
1989                 self.ibox(0);
1990             }
1991             ast::ExprKind::Block(ref blk, opt_label) => {
1992                 if let Some(label) = opt_label {
1993                     self.print_ident(label.ident);
1994                     self.word_space(":");
1995                 }
1996                 // containing cbox, will be closed by print-block at }
1997                 self.cbox(INDENT_UNIT);
1998                 // head-box, will be closed by print-block after {
1999                 self.ibox(0);
2000                 self.print_block_with_attrs(blk, attrs);
2001             }
2002             ast::ExprKind::Async(capture_clause, _, ref blk) => {
2003                 self.word_nbsp("async");
2004                 self.print_capture_clause(capture_clause);
2005                 self.s.space();
2006                 // cbox/ibox in analogy to the `ExprKind::Block` arm above
2007                 self.cbox(INDENT_UNIT);
2008                 self.ibox(0);
2009                 self.print_block_with_attrs(blk, attrs);
2010             }
2011             ast::ExprKind::Await(ref expr) => {
2012                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2013                 self.s.word(".await");
2014             }
2015             ast::ExprKind::Assign(ref lhs, ref rhs, _) => {
2016                 let prec = AssocOp::Assign.precedence() as i8;
2017                 self.print_expr_maybe_paren(lhs, prec + 1);
2018                 self.s.space();
2019                 self.word_space("=");
2020                 self.print_expr_maybe_paren(rhs, prec);
2021             }
2022             ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
2023                 let prec = AssocOp::Assign.precedence() as i8;
2024                 self.print_expr_maybe_paren(lhs, prec + 1);
2025                 self.s.space();
2026                 self.s.word(op.node.to_string());
2027                 self.word_space("=");
2028                 self.print_expr_maybe_paren(rhs, prec);
2029             }
2030             ast::ExprKind::Field(ref expr, ident) => {
2031                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2032                 self.s.word(".");
2033                 self.print_ident(ident);
2034             }
2035             ast::ExprKind::Index(ref expr, ref index) => {
2036                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2037                 self.s.word("[");
2038                 self.print_expr(index);
2039                 self.s.word("]");
2040             }
2041             ast::ExprKind::Range(ref start, ref end, limits) => {
2042                 // Special case for `Range`.  `AssocOp` claims that `Range` has higher precedence
2043                 // than `Assign`, but `x .. x = x` gives a parse error instead of `x .. (x = x)`.
2044                 // Here we use a fake precedence value so that any child with lower precedence than
2045                 // a "normal" binop gets parenthesized.  (`LOr` is the lowest-precedence binop.)
2046                 let fake_prec = AssocOp::LOr.precedence() as i8;
2047                 if let Some(ref e) = *start {
2048                     self.print_expr_maybe_paren(e, fake_prec);
2049                 }
2050                 if limits == ast::RangeLimits::HalfOpen {
2051                     self.s.word("..");
2052                 } else {
2053                     self.s.word("..=");
2054                 }
2055                 if let Some(ref e) = *end {
2056                     self.print_expr_maybe_paren(e, fake_prec);
2057                 }
2058             }
2059             ast::ExprKind::Path(None, ref path) => self.print_path(path, true, 0),
2060             ast::ExprKind::Path(Some(ref qself), ref path) => self.print_qpath(path, qself, true),
2061             ast::ExprKind::Break(opt_label, ref opt_expr) => {
2062                 self.s.word("break");
2063                 self.s.space();
2064                 if let Some(label) = opt_label {
2065                     self.print_ident(label.ident);
2066                     self.s.space();
2067                 }
2068                 if let Some(ref expr) = *opt_expr {
2069                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2070                     self.s.space();
2071                 }
2072             }
2073             ast::ExprKind::Continue(opt_label) => {
2074                 self.s.word("continue");
2075                 self.s.space();
2076                 if let Some(label) = opt_label {
2077                     self.print_ident(label.ident);
2078                     self.s.space()
2079                 }
2080             }
2081             ast::ExprKind::Ret(ref result) => {
2082                 self.s.word("return");
2083                 if let Some(ref expr) = *result {
2084                     self.s.word(" ");
2085                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2086                 }
2087             }
2088             ast::ExprKind::InlineAsm(ref a) => {
2089                 self.s.word("asm!");
2090                 self.popen();
2091                 self.print_string(&a.asm.as_str(), a.asm_str_style);
2092                 self.word_space(":");
2093
2094                 self.commasep(Inconsistent, &a.outputs, |s, out| {
2095                     let constraint = out.constraint.as_str();
2096                     let mut ch = constraint.chars();
2097                     match ch.next() {
2098                         Some('=') if out.is_rw => {
2099                             s.print_string(&format!("+{}", ch.as_str()), ast::StrStyle::Cooked)
2100                         }
2101                         _ => s.print_string(&constraint, ast::StrStyle::Cooked),
2102                     }
2103                     s.popen();
2104                     s.print_expr(&out.expr);
2105                     s.pclose();
2106                 });
2107                 self.s.space();
2108                 self.word_space(":");
2109
2110                 self.commasep(Inconsistent, &a.inputs, |s, &(co, ref o)| {
2111                     s.print_string(&co.as_str(), ast::StrStyle::Cooked);
2112                     s.popen();
2113                     s.print_expr(o);
2114                     s.pclose();
2115                 });
2116                 self.s.space();
2117                 self.word_space(":");
2118
2119                 self.commasep(Inconsistent, &a.clobbers, |s, co| {
2120                     s.print_string(&co.as_str(), ast::StrStyle::Cooked);
2121                 });
2122
2123                 let mut options = vec![];
2124                 if a.volatile {
2125                     options.push("volatile");
2126                 }
2127                 if a.alignstack {
2128                     options.push("alignstack");
2129                 }
2130                 if a.dialect == ast::AsmDialect::Intel {
2131                     options.push("intel");
2132                 }
2133
2134                 if !options.is_empty() {
2135                     self.s.space();
2136                     self.word_space(":");
2137                     self.commasep(Inconsistent, &options, |s, &co| {
2138                         s.print_string(co, ast::StrStyle::Cooked);
2139                     });
2140                 }
2141
2142                 self.pclose();
2143             }
2144             ast::ExprKind::Mac(ref m) => self.print_mac(m),
2145             ast::ExprKind::Paren(ref e) => {
2146                 self.popen();
2147                 self.print_inner_attributes_inline(attrs);
2148                 self.print_expr(e);
2149                 self.pclose();
2150             }
2151             ast::ExprKind::Yield(ref e) => {
2152                 self.s.word("yield");
2153                 match *e {
2154                     Some(ref expr) => {
2155                         self.s.space();
2156                         self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2157                     }
2158                     _ => (),
2159                 }
2160             }
2161             ast::ExprKind::Try(ref e) => {
2162                 self.print_expr_maybe_paren(e, parser::PREC_POSTFIX);
2163                 self.s.word("?")
2164             }
2165             ast::ExprKind::TryBlock(ref blk) => {
2166                 self.head("try");
2167                 self.s.space();
2168                 self.print_block_with_attrs(blk, attrs)
2169             }
2170             ast::ExprKind::Err => {
2171                 self.popen();
2172                 self.s.word("/*ERROR*/");
2173                 self.pclose()
2174             }
2175         }
2176         self.ann.post(self, AnnNode::Expr(expr));
2177         self.end();
2178     }
2179
2180     crate fn print_local_decl(&mut self, loc: &ast::Local) {
2181         self.print_pat(&loc.pat);
2182         if let Some(ref ty) = loc.ty {
2183             self.word_space(":");
2184             self.print_type(ty);
2185         }
2186     }
2187
2188     pub fn print_usize(&mut self, i: usize) {
2189         self.s.word(i.to_string())
2190     }
2191
2192     crate fn print_name(&mut self, name: ast::Name) {
2193         self.s.word(name.to_string());
2194         self.ann.post(self, AnnNode::Name(&name))
2195     }
2196
2197     fn print_qpath(&mut self, path: &ast::Path, qself: &ast::QSelf, colons_before_params: bool) {
2198         self.s.word("<");
2199         self.print_type(&qself.ty);
2200         if qself.position > 0 {
2201             self.s.space();
2202             self.word_space("as");
2203             let depth = path.segments.len() - qself.position;
2204             self.print_path(path, false, depth);
2205         }
2206         self.s.word(">");
2207         self.s.word("::");
2208         let item_segment = path.segments.last().unwrap();
2209         self.print_ident(item_segment.ident);
2210         match item_segment.args {
2211             Some(ref args) => self.print_generic_args(args, colons_before_params),
2212             None => {}
2213         }
2214     }
2215
2216     crate fn print_pat(&mut self, pat: &ast::Pat) {
2217         self.maybe_print_comment(pat.span.lo());
2218         self.ann.pre(self, AnnNode::Pat(pat));
2219         /* Pat isn't normalized, but the beauty of it
2220         is that it doesn't matter */
2221         match pat.kind {
2222             PatKind::Wild => self.s.word("_"),
2223             PatKind::Ident(binding_mode, ident, ref sub) => {
2224                 match binding_mode {
2225                     ast::BindingMode::ByRef(mutbl) => {
2226                         self.word_nbsp("ref");
2227                         self.print_mutability(mutbl, false);
2228                     }
2229                     ast::BindingMode::ByValue(ast::Mutability::Not) => {}
2230                     ast::BindingMode::ByValue(ast::Mutability::Mut) => {
2231                         self.word_nbsp("mut");
2232                     }
2233                 }
2234                 self.print_ident(ident);
2235                 if let Some(ref p) = *sub {
2236                     self.s.space();
2237                     self.s.word_space("@");
2238                     self.print_pat(p);
2239                 }
2240             }
2241             PatKind::TupleStruct(ref path, ref elts) => {
2242                 self.print_path(path, true, 0);
2243                 self.popen();
2244                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2245                 self.pclose();
2246             }
2247             PatKind::Or(ref pats) => {
2248                 self.strsep("|", true, Inconsistent, &pats[..], |s, p| s.print_pat(p));
2249             }
2250             PatKind::Path(None, ref path) => {
2251                 self.print_path(path, true, 0);
2252             }
2253             PatKind::Path(Some(ref qself), ref path) => {
2254                 self.print_qpath(path, qself, false);
2255             }
2256             PatKind::Struct(ref path, ref fields, etc) => {
2257                 self.print_path(path, true, 0);
2258                 self.nbsp();
2259                 self.word_space("{");
2260                 self.commasep_cmnt(
2261                     Consistent,
2262                     &fields[..],
2263                     |s, f| {
2264                         s.cbox(INDENT_UNIT);
2265                         if !f.is_shorthand {
2266                             s.print_ident(f.ident);
2267                             s.word_nbsp(":");
2268                         }
2269                         s.print_pat(&f.pat);
2270                         s.end();
2271                     },
2272                     |f| f.pat.span,
2273                 );
2274                 if etc {
2275                     if !fields.is_empty() {
2276                         self.word_space(",");
2277                     }
2278                     self.s.word("..");
2279                 }
2280                 self.s.space();
2281                 self.s.word("}");
2282             }
2283             PatKind::Tuple(ref elts) => {
2284                 self.popen();
2285                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2286                 if elts.len() == 1 {
2287                     self.s.word(",");
2288                 }
2289                 self.pclose();
2290             }
2291             PatKind::Box(ref inner) => {
2292                 self.s.word("box ");
2293                 self.print_pat(inner);
2294             }
2295             PatKind::Ref(ref inner, mutbl) => {
2296                 self.s.word("&");
2297                 if mutbl == ast::Mutability::Mut {
2298                     self.s.word("mut ");
2299                 }
2300                 self.print_pat(inner);
2301             }
2302             PatKind::Lit(ref e) => self.print_expr(&**e),
2303             PatKind::Range(ref begin, ref end, Spanned { node: ref end_kind, .. }) => {
2304                 if let Some(e) = begin {
2305                     self.print_expr(e);
2306                     self.s.space();
2307                 }
2308                 match *end_kind {
2309                     RangeEnd::Included(RangeSyntax::DotDotDot) => self.s.word("..."),
2310                     RangeEnd::Included(RangeSyntax::DotDotEq) => self.s.word("..="),
2311                     RangeEnd::Excluded => self.s.word(".."),
2312                 }
2313                 if let Some(e) = end {
2314                     self.print_expr(e);
2315                 }
2316             }
2317             PatKind::Slice(ref elts) => {
2318                 self.s.word("[");
2319                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2320                 self.s.word("]");
2321             }
2322             PatKind::Rest => self.s.word(".."),
2323             PatKind::Paren(ref inner) => {
2324                 self.popen();
2325                 self.print_pat(inner);
2326                 self.pclose();
2327             }
2328             PatKind::Mac(ref m) => self.print_mac(m),
2329         }
2330         self.ann.post(self, AnnNode::Pat(pat))
2331     }
2332
2333     fn print_arm(&mut self, arm: &ast::Arm) {
2334         // Note, I have no idea why this check is necessary, but here it is.
2335         if arm.attrs.is_empty() {
2336             self.s.space();
2337         }
2338         self.cbox(INDENT_UNIT);
2339         self.ibox(0);
2340         self.maybe_print_comment(arm.pat.span.lo());
2341         self.print_outer_attributes(&arm.attrs);
2342         self.print_pat(&arm.pat);
2343         self.s.space();
2344         if let Some(ref e) = arm.guard {
2345             self.word_space("if");
2346             self.print_expr(e);
2347             self.s.space();
2348         }
2349         self.word_space("=>");
2350
2351         match arm.body.kind {
2352             ast::ExprKind::Block(ref blk, opt_label) => {
2353                 if let Some(label) = opt_label {
2354                     self.print_ident(label.ident);
2355                     self.word_space(":");
2356                 }
2357
2358                 // The block will close the pattern's ibox.
2359                 self.print_block_unclosed_indent(blk);
2360
2361                 // If it is a user-provided unsafe block, print a comma after it.
2362                 if let BlockCheckMode::Unsafe(ast::UserProvided) = blk.rules {
2363                     self.s.word(",");
2364                 }
2365             }
2366             _ => {
2367                 self.end(); // Close the ibox for the pattern.
2368                 self.print_expr(&arm.body);
2369                 self.s.word(",");
2370             }
2371         }
2372         self.end(); // Close enclosing cbox.
2373     }
2374
2375     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) {
2376         match explicit_self.node {
2377             SelfKind::Value(m) => {
2378                 self.print_mutability(m, false);
2379                 self.s.word("self")
2380             }
2381             SelfKind::Region(ref lt, m) => {
2382                 self.s.word("&");
2383                 self.print_opt_lifetime(lt);
2384                 self.print_mutability(m, false);
2385                 self.s.word("self")
2386             }
2387             SelfKind::Explicit(ref typ, m) => {
2388                 self.print_mutability(m, false);
2389                 self.s.word("self");
2390                 self.word_space(":");
2391                 self.print_type(typ)
2392             }
2393         }
2394     }
2395
2396     fn print_fn_full(
2397         &mut self,
2398         sig: &ast::FnSig,
2399         name: ast::Ident,
2400         generics: &ast::Generics,
2401         vis: &ast::Visibility,
2402         body: Option<&ast::Block>,
2403         attrs: &[ast::Attribute],
2404     ) {
2405         if body.is_some() {
2406             self.head("");
2407         }
2408         self.print_fn(&sig.decl, sig.header, Some(name), generics, vis);
2409         if let Some(body) = body {
2410             self.nbsp();
2411             self.print_block_with_attrs(body, attrs);
2412         } else {
2413             self.s.word(";");
2414         }
2415     }
2416
2417     crate fn print_fn(
2418         &mut self,
2419         decl: &ast::FnDecl,
2420         header: ast::FnHeader,
2421         name: Option<ast::Ident>,
2422         generics: &ast::Generics,
2423         vis: &ast::Visibility,
2424     ) {
2425         self.print_fn_header_info(header, vis);
2426
2427         if let Some(name) = name {
2428             self.nbsp();
2429             self.print_ident(name);
2430         }
2431         self.print_generic_params(&generics.params);
2432         self.print_fn_params_and_ret(decl, false);
2433         self.print_where_clause(&generics.where_clause)
2434     }
2435
2436     crate fn print_fn_params_and_ret(&mut self, decl: &ast::FnDecl, is_closure: bool) {
2437         let (open, close) = if is_closure { ("|", "|") } else { ("(", ")") };
2438         self.word(open);
2439         self.commasep(Inconsistent, &decl.inputs, |s, param| s.print_param(param, is_closure));
2440         self.word(close);
2441         self.print_fn_ret_ty(&decl.output)
2442     }
2443
2444     crate fn print_movability(&mut self, movability: ast::Movability) {
2445         match movability {
2446             ast::Movability::Static => self.word_space("static"),
2447             ast::Movability::Movable => {}
2448         }
2449     }
2450
2451     crate fn print_asyncness(&mut self, asyncness: ast::Async) {
2452         if asyncness.is_async() {
2453             self.word_nbsp("async");
2454         }
2455     }
2456
2457     crate fn print_capture_clause(&mut self, capture_clause: ast::CaptureBy) {
2458         match capture_clause {
2459             ast::CaptureBy::Value => self.word_space("move"),
2460             ast::CaptureBy::Ref => {}
2461         }
2462     }
2463
2464     pub fn print_type_bounds(&mut self, prefix: &'static str, bounds: &[ast::GenericBound]) {
2465         if !bounds.is_empty() {
2466             self.s.word(prefix);
2467             let mut first = true;
2468             for bound in bounds {
2469                 if !(first && prefix.is_empty()) {
2470                     self.nbsp();
2471                 }
2472                 if first {
2473                     first = false;
2474                 } else {
2475                     self.word_space("+");
2476                 }
2477
2478                 match bound {
2479                     GenericBound::Trait(tref, modifier) => {
2480                         if modifier == &TraitBoundModifier::Maybe {
2481                             self.s.word("?");
2482                         }
2483                         self.print_poly_trait_ref(tref);
2484                     }
2485                     GenericBound::Outlives(lt) => self.print_lifetime(*lt),
2486                 }
2487             }
2488         }
2489     }
2490
2491     crate fn print_lifetime(&mut self, lifetime: ast::Lifetime) {
2492         self.print_name(lifetime.ident.name)
2493     }
2494
2495     crate fn print_lifetime_bounds(
2496         &mut self,
2497         lifetime: ast::Lifetime,
2498         bounds: &ast::GenericBounds,
2499     ) {
2500         self.print_lifetime(lifetime);
2501         if !bounds.is_empty() {
2502             self.s.word(": ");
2503             for (i, bound) in bounds.iter().enumerate() {
2504                 if i != 0 {
2505                     self.s.word(" + ");
2506                 }
2507                 match bound {
2508                     ast::GenericBound::Outlives(lt) => self.print_lifetime(*lt),
2509                     _ => panic!(),
2510                 }
2511             }
2512         }
2513     }
2514
2515     crate fn print_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
2516         if generic_params.is_empty() {
2517             return;
2518         }
2519
2520         self.s.word("<");
2521
2522         self.commasep(Inconsistent, &generic_params, |s, param| {
2523             s.print_outer_attributes_inline(&param.attrs);
2524
2525             match param.kind {
2526                 ast::GenericParamKind::Lifetime => {
2527                     let lt = ast::Lifetime { id: param.id, ident: param.ident };
2528                     s.print_lifetime_bounds(lt, &param.bounds)
2529                 }
2530                 ast::GenericParamKind::Type { ref default } => {
2531                     s.print_ident(param.ident);
2532                     s.print_type_bounds(":", &param.bounds);
2533                     if let Some(ref default) = default {
2534                         s.s.space();
2535                         s.word_space("=");
2536                         s.print_type(default)
2537                     }
2538                 }
2539                 ast::GenericParamKind::Const { ref ty } => {
2540                     s.word_space("const");
2541                     s.print_ident(param.ident);
2542                     s.s.space();
2543                     s.word_space(":");
2544                     s.print_type(ty);
2545                     s.print_type_bounds(":", &param.bounds)
2546                 }
2547             }
2548         });
2549
2550         self.s.word(">");
2551     }
2552
2553     crate fn print_where_clause(&mut self, where_clause: &ast::WhereClause) {
2554         if where_clause.predicates.is_empty() {
2555             return;
2556         }
2557
2558         self.s.space();
2559         self.word_space("where");
2560
2561         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2562             if i != 0 {
2563                 self.word_space(",");
2564             }
2565
2566             match *predicate {
2567                 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
2568                     ref bound_generic_params,
2569                     ref bounded_ty,
2570                     ref bounds,
2571                     ..
2572                 }) => {
2573                     self.print_formal_generic_params(bound_generic_params);
2574                     self.print_type(bounded_ty);
2575                     self.print_type_bounds(":", bounds);
2576                 }
2577                 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
2578                     ref lifetime,
2579                     ref bounds,
2580                     ..
2581                 }) => {
2582                     self.print_lifetime_bounds(*lifetime, bounds);
2583                 }
2584                 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
2585                     ref lhs_ty,
2586                     ref rhs_ty,
2587                     ..
2588                 }) => {
2589                     self.print_type(lhs_ty);
2590                     self.s.space();
2591                     self.word_space("=");
2592                     self.print_type(rhs_ty);
2593                 }
2594             }
2595         }
2596     }
2597
2598     crate fn print_use_tree(&mut self, tree: &ast::UseTree) {
2599         match tree.kind {
2600             ast::UseTreeKind::Simple(rename, ..) => {
2601                 self.print_path(&tree.prefix, false, 0);
2602                 if let Some(rename) = rename {
2603                     self.s.space();
2604                     self.word_space("as");
2605                     self.print_ident(rename);
2606                 }
2607             }
2608             ast::UseTreeKind::Glob => {
2609                 if !tree.prefix.segments.is_empty() {
2610                     self.print_path(&tree.prefix, false, 0);
2611                     self.s.word("::");
2612                 }
2613                 self.s.word("*");
2614             }
2615             ast::UseTreeKind::Nested(ref items) => {
2616                 if tree.prefix.segments.is_empty() {
2617                     self.s.word("{");
2618                 } else {
2619                     self.print_path(&tree.prefix, false, 0);
2620                     self.s.word("::{");
2621                 }
2622                 self.commasep(Inconsistent, &items[..], |this, &(ref tree, _)| {
2623                     this.print_use_tree(tree)
2624                 });
2625                 self.s.word("}");
2626             }
2627         }
2628     }
2629
2630     pub fn print_mutability(&mut self, mutbl: ast::Mutability, print_const: bool) {
2631         match mutbl {
2632             ast::Mutability::Mut => self.word_nbsp("mut"),
2633             ast::Mutability::Not => {
2634                 if print_const {
2635                     self.word_nbsp("const");
2636                 }
2637             }
2638         }
2639     }
2640
2641     crate fn print_mt(&mut self, mt: &ast::MutTy, print_const: bool) {
2642         self.print_mutability(mt.mutbl, print_const);
2643         self.print_type(&mt.ty)
2644     }
2645
2646     crate fn print_param(&mut self, input: &ast::Param, is_closure: bool) {
2647         self.ibox(INDENT_UNIT);
2648
2649         self.print_outer_attributes_inline(&input.attrs);
2650
2651         match input.ty.kind {
2652             ast::TyKind::Infer if is_closure => self.print_pat(&input.pat),
2653             _ => {
2654                 if let Some(eself) = input.to_self() {
2655                     self.print_explicit_self(&eself);
2656                 } else {
2657                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.kind {
2658                         ident.name == kw::Invalid
2659                     } else {
2660                         false
2661                     };
2662                     if !invalid {
2663                         self.print_pat(&input.pat);
2664                         self.s.word(":");
2665                         self.s.space();
2666                     }
2667                     self.print_type(&input.ty);
2668                 }
2669             }
2670         }
2671         self.end();
2672     }
2673
2674     crate fn print_fn_ret_ty(&mut self, fn_ret_ty: &ast::FunctionRetTy) {
2675         if let ast::FunctionRetTy::Ty(ty) = fn_ret_ty {
2676             self.space_if_not_bol();
2677             self.ibox(INDENT_UNIT);
2678             self.word_space("->");
2679             self.print_type(ty);
2680             self.end();
2681             self.maybe_print_comment(ty.span.lo());
2682         }
2683     }
2684
2685     crate fn print_ty_fn(
2686         &mut self,
2687         ext: ast::Extern,
2688         unsafety: ast::Unsafe,
2689         decl: &ast::FnDecl,
2690         name: Option<ast::Ident>,
2691         generic_params: &[ast::GenericParam],
2692     ) {
2693         self.ibox(INDENT_UNIT);
2694         if !generic_params.is_empty() {
2695             self.s.word("for");
2696             self.print_generic_params(generic_params);
2697         }
2698         let generics = ast::Generics {
2699             params: Vec::new(),
2700             where_clause: ast::WhereClause { predicates: Vec::new(), span: rustc_span::DUMMY_SP },
2701             span: rustc_span::DUMMY_SP,
2702         };
2703         let header = ast::FnHeader { unsafety, ext, ..ast::FnHeader::default() };
2704         let vis = dummy_spanned(ast::VisibilityKind::Inherited);
2705         self.print_fn(decl, header, name, &generics, &vis);
2706         self.end();
2707     }
2708
2709     crate fn maybe_print_trailing_comment(
2710         &mut self,
2711         span: rustc_span::Span,
2712         next_pos: Option<BytePos>,
2713     ) {
2714         if let Some(cmnts) = self.comments() {
2715             if let Some(cmnt) = cmnts.trailing_comment(span, next_pos) {
2716                 self.print_comment(&cmnt);
2717             }
2718         }
2719     }
2720
2721     crate fn print_remaining_comments(&mut self) {
2722         // If there aren't any remaining comments, then we need to manually
2723         // make sure there is a line break at the end.
2724         if self.next_comment().is_none() {
2725             self.s.hardbreak();
2726         }
2727         while let Some(ref cmnt) = self.next_comment() {
2728             self.print_comment(cmnt);
2729         }
2730     }
2731
2732     crate fn print_fn_header_info(&mut self, header: ast::FnHeader, vis: &ast::Visibility) {
2733         self.s.word(visibility_qualified(vis, ""));
2734
2735         self.print_constness(header.constness);
2736         self.print_asyncness(header.asyncness);
2737         self.print_unsafety(header.unsafety);
2738
2739         match header.ext {
2740             ast::Extern::None => {}
2741             ast::Extern::Implicit => {
2742                 self.word_nbsp("extern");
2743             }
2744             ast::Extern::Explicit(abi) => {
2745                 self.word_nbsp("extern");
2746                 self.print_literal(&abi.as_lit());
2747                 self.nbsp();
2748             }
2749         }
2750
2751         self.s.word("fn")
2752     }
2753
2754     crate fn print_unsafety(&mut self, s: ast::Unsafe) {
2755         match s {
2756             ast::Unsafe::No => {}
2757             ast::Unsafe::Yes(_) => self.word_nbsp("unsafe"),
2758         }
2759     }
2760
2761     crate fn print_constness(&mut self, s: ast::Const) {
2762         match s {
2763             ast::Const::No => {}
2764             ast::Const::Yes(_) => self.word_nbsp("const"),
2765         }
2766     }
2767
2768     crate fn print_is_auto(&mut self, s: ast::IsAuto) {
2769         match s {
2770             ast::IsAuto::Yes => self.word_nbsp("auto"),
2771             ast::IsAuto::No => {}
2772         }
2773     }
2774 }