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(ref sig, ref gen, ref body) => {
1024                 self.print_fn_full(sig, item.ident, gen, &item.vis, body.as_deref(), &item.attrs);
1025             }
1026             ast::ForeignItemKind::Static(ref 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::Ty => {
1039                 self.head(visibility_qualified(&item.vis, "type"));
1040                 self.print_ident(item.ident);
1041                 self.s.word(";");
1042                 self.end(); // end the head-ibox
1043                 self.end(); // end the outer cbox
1044             }
1045             ast::ForeignItemKind::Macro(ref m) => {
1046                 self.print_mac(m);
1047                 if m.args.need_semicolon() {
1048                     self.s.word(";");
1049                 }
1050             }
1051         }
1052     }
1053
1054     fn print_associated_const(
1055         &mut self,
1056         ident: ast::Ident,
1057         ty: &ast::Ty,
1058         default: Option<&ast::Expr>,
1059         vis: &ast::Visibility,
1060     ) {
1061         self.s.word(visibility_qualified(vis, ""));
1062         self.word_space("const");
1063         self.print_ident(ident);
1064         self.word_space(":");
1065         self.print_type(ty);
1066         if let Some(expr) = default {
1067             self.s.space();
1068             self.word_space("=");
1069             self.print_expr(expr);
1070         }
1071         self.s.word(";")
1072     }
1073
1074     fn print_associated_type(
1075         &mut self,
1076         ident: ast::Ident,
1077         generics: &ast::Generics,
1078         bounds: &ast::GenericBounds,
1079         ty: Option<&ast::Ty>,
1080     ) {
1081         self.word_space("type");
1082         self.print_ident(ident);
1083         self.print_generic_params(&generics.params);
1084         self.print_type_bounds(":", bounds);
1085         self.print_where_clause(&generics.where_clause);
1086         if let Some(ty) = ty {
1087             self.s.space();
1088             self.word_space("=");
1089             self.print_type(ty);
1090         }
1091         self.s.word(";")
1092     }
1093
1094     /// Pretty-prints an item.
1095     crate fn print_item(&mut self, item: &ast::Item) {
1096         self.hardbreak_if_not_bol();
1097         self.maybe_print_comment(item.span.lo());
1098         self.print_outer_attributes(&item.attrs);
1099         self.ann.pre(self, AnnNode::Item(item));
1100         match item.kind {
1101             ast::ItemKind::ExternCrate(orig_name) => {
1102                 self.head(visibility_qualified(&item.vis, "extern crate"));
1103                 if let Some(orig_name) = orig_name {
1104                     self.print_name(orig_name);
1105                     self.s.space();
1106                     self.s.word("as");
1107                     self.s.space();
1108                 }
1109                 self.print_ident(item.ident);
1110                 self.s.word(";");
1111                 self.end(); // end inner head-block
1112                 self.end(); // end outer head-block
1113             }
1114             ast::ItemKind::Use(ref tree) => {
1115                 self.head(visibility_qualified(&item.vis, "use"));
1116                 self.print_use_tree(tree);
1117                 self.s.word(";");
1118                 self.end(); // end inner head-block
1119                 self.end(); // end outer head-block
1120             }
1121             ast::ItemKind::Static(ref ty, m, ref expr) => {
1122                 self.head(visibility_qualified(&item.vis, "static"));
1123                 if m == ast::Mutability::Mut {
1124                     self.word_space("mut");
1125                 }
1126                 self.print_ident(item.ident);
1127                 self.word_space(":");
1128                 self.print_type(ty);
1129                 self.s.space();
1130                 self.end(); // end the head-ibox
1131
1132                 self.word_space("=");
1133                 self.print_expr(expr);
1134                 self.s.word(";");
1135                 self.end(); // end the outer cbox
1136             }
1137             ast::ItemKind::Const(ref ty, ref expr) => {
1138                 self.head(visibility_qualified(&item.vis, "const"));
1139                 self.print_ident(item.ident);
1140                 self.word_space(":");
1141                 self.print_type(ty);
1142                 self.s.space();
1143                 self.end(); // end the head-ibox
1144
1145                 self.word_space("=");
1146                 self.print_expr(expr);
1147                 self.s.word(";");
1148                 self.end(); // end the outer cbox
1149             }
1150             ast::ItemKind::Fn(ref sig, ref gen, ref body) => {
1151                 self.print_fn_full(sig, item.ident, gen, &item.vis, body.as_deref(), &item.attrs);
1152             }
1153             ast::ItemKind::Mod(ref _mod) => {
1154                 self.head(visibility_qualified(&item.vis, "mod"));
1155                 self.print_ident(item.ident);
1156
1157                 if _mod.inline || self.is_expanded {
1158                     self.nbsp();
1159                     self.bopen();
1160                     self.print_mod(_mod, &item.attrs);
1161                     self.bclose(item.span);
1162                 } else {
1163                     self.s.word(";");
1164                     self.end(); // end inner head-block
1165                     self.end(); // end outer head-block
1166                 }
1167             }
1168             ast::ItemKind::ForeignMod(ref nmod) => {
1169                 self.head("extern");
1170                 if let Some(abi) = nmod.abi {
1171                     self.print_literal(&abi.as_lit());
1172                     self.nbsp();
1173                 }
1174                 self.bopen();
1175                 self.print_foreign_mod(nmod, &item.attrs);
1176                 self.bclose(item.span);
1177             }
1178             ast::ItemKind::GlobalAsm(ref ga) => {
1179                 self.head(visibility_qualified(&item.vis, "global_asm!"));
1180                 self.s.word(ga.asm.to_string());
1181                 self.end();
1182             }
1183             ast::ItemKind::TyAlias(ref ty, ref generics) => {
1184                 self.head(visibility_qualified(&item.vis, "type"));
1185                 self.print_ident(item.ident);
1186                 self.print_generic_params(&generics.params);
1187                 self.end(); // end the inner ibox
1188
1189                 self.print_where_clause(&generics.where_clause);
1190                 self.s.space();
1191                 self.word_space("=");
1192                 self.print_type(ty);
1193                 self.s.word(";");
1194                 self.end(); // end the outer ibox
1195             }
1196             ast::ItemKind::Enum(ref enum_definition, ref params) => {
1197                 self.print_enum_def(enum_definition, params, item.ident, item.span, &item.vis);
1198             }
1199             ast::ItemKind::Struct(ref struct_def, ref generics) => {
1200                 self.head(visibility_qualified(&item.vis, "struct"));
1201                 self.print_struct(struct_def, generics, item.ident, item.span, true);
1202             }
1203             ast::ItemKind::Union(ref struct_def, ref generics) => {
1204                 self.head(visibility_qualified(&item.vis, "union"));
1205                 self.print_struct(struct_def, generics, item.ident, item.span, true);
1206             }
1207             ast::ItemKind::Impl {
1208                 unsafety,
1209                 polarity,
1210                 defaultness,
1211                 constness,
1212                 ref generics,
1213                 ref of_trait,
1214                 ref self_ty,
1215                 ref items,
1216             } => {
1217                 self.head("");
1218                 self.print_visibility(&item.vis);
1219                 self.print_defaultness(defaultness);
1220                 self.print_unsafety(unsafety);
1221                 self.word_nbsp("impl");
1222                 self.print_constness(constness);
1223
1224                 if !generics.params.is_empty() {
1225                     self.print_generic_params(&generics.params);
1226                     self.s.space();
1227                 }
1228
1229                 if polarity == ast::ImplPolarity::Negative {
1230                     self.s.word("!");
1231                 }
1232
1233                 if let Some(ref t) = *of_trait {
1234                     self.print_trait_ref(t);
1235                     self.s.space();
1236                     self.word_space("for");
1237                 }
1238
1239                 self.print_type(self_ty);
1240                 self.print_where_clause(&generics.where_clause);
1241
1242                 self.s.space();
1243                 self.bopen();
1244                 self.print_inner_attributes(&item.attrs);
1245                 for impl_item in items {
1246                     self.print_assoc_item(impl_item);
1247                 }
1248                 self.bclose(item.span);
1249             }
1250             ast::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref trait_items) => {
1251                 self.head("");
1252                 self.print_visibility(&item.vis);
1253                 self.print_unsafety(unsafety);
1254                 self.print_is_auto(is_auto);
1255                 self.word_nbsp("trait");
1256                 self.print_ident(item.ident);
1257                 self.print_generic_params(&generics.params);
1258                 let mut real_bounds = Vec::with_capacity(bounds.len());
1259                 for b in bounds.iter() {
1260                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1261                         self.s.space();
1262                         self.word_space("for ?");
1263                         self.print_trait_ref(&ptr.trait_ref);
1264                     } else {
1265                         real_bounds.push(b.clone());
1266                     }
1267                 }
1268                 self.print_type_bounds(":", &real_bounds[..]);
1269                 self.print_where_clause(&generics.where_clause);
1270                 self.s.word(" ");
1271                 self.bopen();
1272                 for trait_item in trait_items {
1273                     self.print_assoc_item(trait_item);
1274                 }
1275                 self.bclose(item.span);
1276             }
1277             ast::ItemKind::TraitAlias(ref generics, ref bounds) => {
1278                 self.head("");
1279                 self.print_visibility(&item.vis);
1280                 self.word_nbsp("trait");
1281                 self.print_ident(item.ident);
1282                 self.print_generic_params(&generics.params);
1283                 let mut real_bounds = Vec::with_capacity(bounds.len());
1284                 // FIXME(durka) this seems to be some quite outdated syntax
1285                 for b in bounds.iter() {
1286                     if let GenericBound::Trait(ref ptr, ast::TraitBoundModifier::Maybe) = *b {
1287                         self.s.space();
1288                         self.word_space("for ?");
1289                         self.print_trait_ref(&ptr.trait_ref);
1290                     } else {
1291                         real_bounds.push(b.clone());
1292                     }
1293                 }
1294                 self.nbsp();
1295                 self.print_type_bounds("=", &real_bounds[..]);
1296                 self.print_where_clause(&generics.where_clause);
1297                 self.s.word(";");
1298             }
1299             ast::ItemKind::Mac(ref mac) => {
1300                 self.print_mac(mac);
1301                 if mac.args.need_semicolon() {
1302                     self.s.word(";");
1303                 }
1304             }
1305             ast::ItemKind::MacroDef(ref macro_def) => {
1306                 let (kw, has_bang) = if macro_def.legacy {
1307                     ("macro_rules", true)
1308                 } else {
1309                     self.print_visibility(&item.vis);
1310                     ("macro", false)
1311                 };
1312                 self.print_mac_common(
1313                     Some(MacHeader::Keyword(kw)),
1314                     has_bang,
1315                     Some(item.ident),
1316                     macro_def.body.delim(),
1317                     macro_def.body.inner_tokens(),
1318                     true,
1319                     item.span,
1320                 );
1321             }
1322         }
1323         self.ann.post(self, AnnNode::Item(item))
1324     }
1325
1326     fn print_trait_ref(&mut self, t: &ast::TraitRef) {
1327         self.print_path(&t.path, false, 0)
1328     }
1329
1330     fn print_formal_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
1331         if !generic_params.is_empty() {
1332             self.s.word("for");
1333             self.print_generic_params(generic_params);
1334             self.nbsp();
1335         }
1336     }
1337
1338     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) {
1339         self.print_formal_generic_params(&t.bound_generic_params);
1340         self.print_trait_ref(&t.trait_ref)
1341     }
1342
1343     crate fn print_enum_def(
1344         &mut self,
1345         enum_definition: &ast::EnumDef,
1346         generics: &ast::Generics,
1347         ident: ast::Ident,
1348         span: rustc_span::Span,
1349         visibility: &ast::Visibility,
1350     ) {
1351         self.head(visibility_qualified(visibility, "enum"));
1352         self.print_ident(ident);
1353         self.print_generic_params(&generics.params);
1354         self.print_where_clause(&generics.where_clause);
1355         self.s.space();
1356         self.print_variants(&enum_definition.variants, span)
1357     }
1358
1359     crate fn print_variants(&mut self, variants: &[ast::Variant], span: rustc_span::Span) {
1360         self.bopen();
1361         for v in variants {
1362             self.space_if_not_bol();
1363             self.maybe_print_comment(v.span.lo());
1364             self.print_outer_attributes(&v.attrs);
1365             self.ibox(INDENT_UNIT);
1366             self.print_variant(v);
1367             self.s.word(",");
1368             self.end();
1369             self.maybe_print_trailing_comment(v.span, None);
1370         }
1371         self.bclose(span)
1372     }
1373
1374     crate fn print_visibility(&mut self, vis: &ast::Visibility) {
1375         match vis.node {
1376             ast::VisibilityKind::Public => self.word_nbsp("pub"),
1377             ast::VisibilityKind::Crate(sugar) => match sugar {
1378                 ast::CrateSugar::PubCrate => self.word_nbsp("pub(crate)"),
1379                 ast::CrateSugar::JustCrate => self.word_nbsp("crate"),
1380             },
1381             ast::VisibilityKind::Restricted { ref path, .. } => {
1382                 let path = to_string(|s| s.print_path(path, false, 0));
1383                 if path == "self" || path == "super" {
1384                     self.word_nbsp(format!("pub({})", path))
1385                 } else {
1386                     self.word_nbsp(format!("pub(in {})", path))
1387                 }
1388             }
1389             ast::VisibilityKind::Inherited => {}
1390         }
1391     }
1392
1393     crate fn print_defaultness(&mut self, defaultness: ast::Defaultness) {
1394         if let ast::Defaultness::Default = defaultness {
1395             self.word_nbsp("default");
1396         }
1397     }
1398
1399     crate fn print_struct(
1400         &mut self,
1401         struct_def: &ast::VariantData,
1402         generics: &ast::Generics,
1403         ident: ast::Ident,
1404         span: rustc_span::Span,
1405         print_finalizer: bool,
1406     ) {
1407         self.print_ident(ident);
1408         self.print_generic_params(&generics.params);
1409         match struct_def {
1410             ast::VariantData::Tuple(..) | ast::VariantData::Unit(..) => {
1411                 if let ast::VariantData::Tuple(..) = struct_def {
1412                     self.popen();
1413                     self.commasep(Inconsistent, struct_def.fields(), |s, field| {
1414                         s.maybe_print_comment(field.span.lo());
1415                         s.print_outer_attributes(&field.attrs);
1416                         s.print_visibility(&field.vis);
1417                         s.print_type(&field.ty)
1418                     });
1419                     self.pclose();
1420                 }
1421                 self.print_where_clause(&generics.where_clause);
1422                 if print_finalizer {
1423                     self.s.word(";");
1424                 }
1425                 self.end();
1426                 self.end(); // Close the outer-box.
1427             }
1428             ast::VariantData::Struct(..) => {
1429                 self.print_where_clause(&generics.where_clause);
1430                 self.nbsp();
1431                 self.bopen();
1432                 self.hardbreak_if_not_bol();
1433
1434                 for field in struct_def.fields() {
1435                     self.hardbreak_if_not_bol();
1436                     self.maybe_print_comment(field.span.lo());
1437                     self.print_outer_attributes(&field.attrs);
1438                     self.print_visibility(&field.vis);
1439                     self.print_ident(field.ident.unwrap());
1440                     self.word_nbsp(":");
1441                     self.print_type(&field.ty);
1442                     self.s.word(",");
1443                 }
1444
1445                 self.bclose(span)
1446             }
1447         }
1448     }
1449
1450     crate fn print_variant(&mut self, v: &ast::Variant) {
1451         self.head("");
1452         self.print_visibility(&v.vis);
1453         let generics = ast::Generics::default();
1454         self.print_struct(&v.data, &generics, v.ident, v.span, false);
1455         match v.disr_expr {
1456             Some(ref d) => {
1457                 self.s.space();
1458                 self.word_space("=");
1459                 self.print_expr(&d.value)
1460             }
1461             _ => {}
1462         }
1463     }
1464
1465     crate fn print_assoc_item(&mut self, item: &ast::AssocItem) {
1466         self.ann.pre(self, AnnNode::SubItem(item.id));
1467         self.hardbreak_if_not_bol();
1468         self.maybe_print_comment(item.span.lo());
1469         self.print_outer_attributes(&item.attrs);
1470         self.print_defaultness(item.defaultness);
1471         match &item.kind {
1472             ast::AssocItemKind::Const(ty, expr) => {
1473                 self.print_associated_const(item.ident, ty, expr.as_deref(), &item.vis);
1474             }
1475             ast::AssocItemKind::Fn(sig, body) => {
1476                 let body = body.as_deref();
1477                 self.print_fn_full(sig, item.ident, &item.generics, &item.vis, body, &item.attrs);
1478             }
1479             ast::AssocItemKind::TyAlias(bounds, ty) => {
1480                 self.print_associated_type(item.ident, &item.generics, bounds, ty.as_deref());
1481             }
1482             ast::AssocItemKind::Macro(mac) => {
1483                 self.print_mac(mac);
1484                 if mac.args.need_semicolon() {
1485                     self.s.word(";");
1486                 }
1487             }
1488         }
1489         self.ann.post(self, AnnNode::SubItem(item.id))
1490     }
1491
1492     crate fn print_stmt(&mut self, st: &ast::Stmt) {
1493         self.maybe_print_comment(st.span.lo());
1494         match st.kind {
1495             ast::StmtKind::Local(ref loc) => {
1496                 self.print_outer_attributes(&loc.attrs);
1497                 self.space_if_not_bol();
1498                 self.ibox(INDENT_UNIT);
1499                 self.word_nbsp("let");
1500
1501                 self.ibox(INDENT_UNIT);
1502                 self.print_local_decl(loc);
1503                 self.end();
1504                 if let Some(ref init) = loc.init {
1505                     self.nbsp();
1506                     self.word_space("=");
1507                     self.print_expr(init);
1508                 }
1509                 self.s.word(";");
1510                 self.end();
1511             }
1512             ast::StmtKind::Item(ref item) => self.print_item(item),
1513             ast::StmtKind::Expr(ref expr) => {
1514                 self.space_if_not_bol();
1515                 self.print_expr_outer_attr_style(expr, false);
1516                 if classify::expr_requires_semi_to_be_stmt(expr) {
1517                     self.s.word(";");
1518                 }
1519             }
1520             ast::StmtKind::Semi(ref expr) => {
1521                 match expr.kind {
1522                     // Filter out empty `Tup` exprs created for the `redundant_semicolon`
1523                     // lint, as they shouldn't be visible and interact poorly
1524                     // with proc macros.
1525                     ast::ExprKind::Tup(ref exprs) if exprs.is_empty() && expr.attrs.is_empty() => {
1526                         ()
1527                     }
1528                     _ => {
1529                         self.space_if_not_bol();
1530                         self.print_expr_outer_attr_style(expr, false);
1531                         self.s.word(";");
1532                     }
1533                 }
1534             }
1535             ast::StmtKind::Mac(ref mac) => {
1536                 let (ref mac, style, ref attrs) = **mac;
1537                 self.space_if_not_bol();
1538                 self.print_outer_attributes(attrs);
1539                 self.print_mac(mac);
1540                 if style == ast::MacStmtStyle::Semicolon {
1541                     self.s.word(";");
1542                 }
1543             }
1544         }
1545         self.maybe_print_trailing_comment(st.span, None)
1546     }
1547
1548     crate fn print_block(&mut self, blk: &ast::Block) {
1549         self.print_block_with_attrs(blk, &[])
1550     }
1551
1552     crate fn print_block_unclosed_indent(&mut self, blk: &ast::Block) {
1553         self.print_block_maybe_unclosed(blk, &[], false)
1554     }
1555
1556     crate fn print_block_with_attrs(&mut self, blk: &ast::Block, attrs: &[ast::Attribute]) {
1557         self.print_block_maybe_unclosed(blk, attrs, true)
1558     }
1559
1560     crate fn print_block_maybe_unclosed(
1561         &mut self,
1562         blk: &ast::Block,
1563         attrs: &[ast::Attribute],
1564         close_box: bool,
1565     ) {
1566         match blk.rules {
1567             BlockCheckMode::Unsafe(..) => self.word_space("unsafe"),
1568             BlockCheckMode::Default => (),
1569         }
1570         self.maybe_print_comment(blk.span.lo());
1571         self.ann.pre(self, AnnNode::Block(blk));
1572         self.bopen();
1573
1574         self.print_inner_attributes(attrs);
1575
1576         for (i, st) in blk.stmts.iter().enumerate() {
1577             match st.kind {
1578                 ast::StmtKind::Expr(ref expr) if i == blk.stmts.len() - 1 => {
1579                     self.maybe_print_comment(st.span.lo());
1580                     self.space_if_not_bol();
1581                     self.print_expr_outer_attr_style(expr, false);
1582                     self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
1583                 }
1584                 _ => self.print_stmt(st),
1585             }
1586         }
1587
1588         self.bclose_maybe_open(blk.span, close_box);
1589         self.ann.post(self, AnnNode::Block(blk))
1590     }
1591
1592     /// Print a `let pat = scrutinee` expression.
1593     crate fn print_let(&mut self, pat: &ast::Pat, scrutinee: &ast::Expr) {
1594         self.s.word("let ");
1595
1596         self.print_pat(pat);
1597         self.s.space();
1598
1599         self.word_space("=");
1600         self.print_expr_cond_paren(
1601             scrutinee,
1602             Self::cond_needs_par(scrutinee)
1603                 || parser::needs_par_as_let_scrutinee(scrutinee.precedence().order()),
1604         )
1605     }
1606
1607     fn print_else(&mut self, els: Option<&ast::Expr>) {
1608         if let Some(_else) = els {
1609             match _else.kind {
1610                 // Another `else if` block.
1611                 ast::ExprKind::If(ref i, ref then, ref e) => {
1612                     self.cbox(INDENT_UNIT - 1);
1613                     self.ibox(0);
1614                     self.s.word(" else if ");
1615                     self.print_expr_as_cond(i);
1616                     self.s.space();
1617                     self.print_block(then);
1618                     self.print_else(e.as_deref())
1619                 }
1620                 // Final `else` block.
1621                 ast::ExprKind::Block(ref b, _) => {
1622                     self.cbox(INDENT_UNIT - 1);
1623                     self.ibox(0);
1624                     self.s.word(" else ");
1625                     self.print_block(b)
1626                 }
1627                 // Constraints would be great here!
1628                 _ => {
1629                     panic!("print_if saw if with weird alternative");
1630                 }
1631             }
1632         }
1633     }
1634
1635     crate fn print_if(&mut self, test: &ast::Expr, blk: &ast::Block, elseopt: Option<&ast::Expr>) {
1636         self.head("if");
1637
1638         self.print_expr_as_cond(test);
1639         self.s.space();
1640
1641         self.print_block(blk);
1642         self.print_else(elseopt)
1643     }
1644
1645     crate fn print_mac(&mut self, m: &ast::Mac) {
1646         self.print_mac_common(
1647             Some(MacHeader::Path(&m.path)),
1648             true,
1649             None,
1650             m.args.delim(),
1651             m.args.inner_tokens(),
1652             true,
1653             m.span(),
1654         );
1655     }
1656
1657     fn print_call_post(&mut self, args: &[P<ast::Expr>]) {
1658         self.popen();
1659         self.commasep_exprs(Inconsistent, args);
1660         self.pclose()
1661     }
1662
1663     crate fn print_expr_maybe_paren(&mut self, expr: &ast::Expr, prec: i8) {
1664         self.print_expr_cond_paren(expr, expr.precedence().order() < prec)
1665     }
1666
1667     /// Prints an expr using syntax that's acceptable in a condition position, such as the `cond` in
1668     /// `if cond { ... }`.
1669     crate fn print_expr_as_cond(&mut self, expr: &ast::Expr) {
1670         self.print_expr_cond_paren(expr, Self::cond_needs_par(expr))
1671     }
1672
1673     /// Does `expr` need parenthesis when printed in a condition position?
1674     fn cond_needs_par(expr: &ast::Expr) -> bool {
1675         match expr.kind {
1676             // These cases need parens due to the parse error observed in #26461: `if return {}`
1677             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1678             ast::ExprKind::Closure(..) | ast::ExprKind::Ret(..) | ast::ExprKind::Break(..) => true,
1679
1680             _ => parser::contains_exterior_struct_lit(expr),
1681         }
1682     }
1683
1684     /// Prints `expr` or `(expr)` when `needs_par` holds.
1685     fn print_expr_cond_paren(&mut self, expr: &ast::Expr, needs_par: bool) {
1686         if needs_par {
1687             self.popen();
1688         }
1689         self.print_expr(expr);
1690         if needs_par {
1691             self.pclose();
1692         }
1693     }
1694
1695     fn print_expr_vec(&mut self, exprs: &[P<ast::Expr>], attrs: &[Attribute]) {
1696         self.ibox(INDENT_UNIT);
1697         self.s.word("[");
1698         self.print_inner_attributes_inline(attrs);
1699         self.commasep_exprs(Inconsistent, &exprs[..]);
1700         self.s.word("]");
1701         self.end();
1702     }
1703
1704     fn print_expr_repeat(
1705         &mut self,
1706         element: &ast::Expr,
1707         count: &ast::AnonConst,
1708         attrs: &[Attribute],
1709     ) {
1710         self.ibox(INDENT_UNIT);
1711         self.s.word("[");
1712         self.print_inner_attributes_inline(attrs);
1713         self.print_expr(element);
1714         self.word_space(";");
1715         self.print_expr(&count.value);
1716         self.s.word("]");
1717         self.end();
1718     }
1719
1720     fn print_expr_struct(
1721         &mut self,
1722         path: &ast::Path,
1723         fields: &[ast::Field],
1724         wth: &Option<P<ast::Expr>>,
1725         attrs: &[Attribute],
1726     ) {
1727         self.print_path(path, true, 0);
1728         self.s.word("{");
1729         self.print_inner_attributes_inline(attrs);
1730         self.commasep_cmnt(
1731             Consistent,
1732             &fields[..],
1733             |s, field| {
1734                 s.print_outer_attributes(&field.attrs);
1735                 s.ibox(INDENT_UNIT);
1736                 if !field.is_shorthand {
1737                     s.print_ident(field.ident);
1738                     s.word_space(":");
1739                 }
1740                 s.print_expr(&field.expr);
1741                 s.end();
1742             },
1743             |f| f.span,
1744         );
1745         match *wth {
1746             Some(ref expr) => {
1747                 self.ibox(INDENT_UNIT);
1748                 if !fields.is_empty() {
1749                     self.s.word(",");
1750                     self.s.space();
1751                 }
1752                 self.s.word("..");
1753                 self.print_expr(expr);
1754                 self.end();
1755             }
1756             _ => {
1757                 if !fields.is_empty() {
1758                     self.s.word(",")
1759                 }
1760             }
1761         }
1762         self.s.word("}");
1763     }
1764
1765     fn print_expr_tup(&mut self, exprs: &[P<ast::Expr>], attrs: &[Attribute]) {
1766         self.popen();
1767         self.print_inner_attributes_inline(attrs);
1768         self.commasep_exprs(Inconsistent, &exprs[..]);
1769         if exprs.len() == 1 {
1770             self.s.word(",");
1771         }
1772         self.pclose()
1773     }
1774
1775     fn print_expr_call(&mut self, func: &ast::Expr, args: &[P<ast::Expr>]) {
1776         let prec = match func.kind {
1777             ast::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1778             _ => parser::PREC_POSTFIX,
1779         };
1780
1781         self.print_expr_maybe_paren(func, prec);
1782         self.print_call_post(args)
1783     }
1784
1785     fn print_expr_method_call(&mut self, segment: &ast::PathSegment, args: &[P<ast::Expr>]) {
1786         let base_args = &args[1..];
1787         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
1788         self.s.word(".");
1789         self.print_ident(segment.ident);
1790         if let Some(ref args) = segment.args {
1791             self.print_generic_args(args, true);
1792         }
1793         self.print_call_post(base_args)
1794     }
1795
1796     fn print_expr_binary(&mut self, op: ast::BinOp, lhs: &ast::Expr, rhs: &ast::Expr) {
1797         let assoc_op = AssocOp::from_ast_binop(op.node);
1798         let prec = assoc_op.precedence() as i8;
1799         let fixity = assoc_op.fixity();
1800
1801         let (left_prec, right_prec) = match fixity {
1802             Fixity::Left => (prec, prec + 1),
1803             Fixity::Right => (prec + 1, prec),
1804             Fixity::None => (prec + 1, prec + 1),
1805         };
1806
1807         let left_prec = match (&lhs.kind, op.node) {
1808             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1809             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1810             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1811             (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Lt)
1812             | (&ast::ExprKind::Cast { .. }, ast::BinOpKind::Shl) => parser::PREC_FORCE_PAREN,
1813             // We are given `(let _ = a) OP b`.
1814             //
1815             // - When `OP <= LAnd` we should print `let _ = a OP b` to avoid redundant parens
1816             //   as the parser will interpret this as `(let _ = a) OP b`.
1817             //
1818             // - Otherwise, e.g. when we have `(let a = b) < c` in AST,
1819             //   parens are required since the parser would interpret `let a = b < c` as
1820             //   `let a = (b < c)`. To achieve this, we force parens.
1821             (&ast::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(prec) => {
1822                 parser::PREC_FORCE_PAREN
1823             }
1824             _ => left_prec,
1825         };
1826
1827         self.print_expr_maybe_paren(lhs, left_prec);
1828         self.s.space();
1829         self.word_space(op.node.to_string());
1830         self.print_expr_maybe_paren(rhs, right_prec)
1831     }
1832
1833     fn print_expr_unary(&mut self, op: ast::UnOp, expr: &ast::Expr) {
1834         self.s.word(ast::UnOp::to_string(op));
1835         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1836     }
1837
1838     fn print_expr_addr_of(
1839         &mut self,
1840         kind: ast::BorrowKind,
1841         mutability: ast::Mutability,
1842         expr: &ast::Expr,
1843     ) {
1844         self.s.word("&");
1845         match kind {
1846             ast::BorrowKind::Ref => self.print_mutability(mutability, false),
1847             ast::BorrowKind::Raw => {
1848                 self.word_nbsp("raw");
1849                 self.print_mutability(mutability, true);
1850             }
1851         }
1852         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1853     }
1854
1855     pub fn print_expr(&mut self, expr: &ast::Expr) {
1856         self.print_expr_outer_attr_style(expr, true)
1857     }
1858
1859     fn print_expr_outer_attr_style(&mut self, expr: &ast::Expr, is_inline: bool) {
1860         self.maybe_print_comment(expr.span.lo());
1861
1862         let attrs = &expr.attrs;
1863         if is_inline {
1864             self.print_outer_attributes_inline(attrs);
1865         } else {
1866             self.print_outer_attributes(attrs);
1867         }
1868
1869         self.ibox(INDENT_UNIT);
1870         self.ann.pre(self, AnnNode::Expr(expr));
1871         match expr.kind {
1872             ast::ExprKind::Box(ref expr) => {
1873                 self.word_space("box");
1874                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX);
1875             }
1876             ast::ExprKind::Array(ref exprs) => {
1877                 self.print_expr_vec(&exprs[..], attrs);
1878             }
1879             ast::ExprKind::Repeat(ref element, ref count) => {
1880                 self.print_expr_repeat(element, count, attrs);
1881             }
1882             ast::ExprKind::Struct(ref path, ref fields, ref wth) => {
1883                 self.print_expr_struct(path, &fields[..], wth, attrs);
1884             }
1885             ast::ExprKind::Tup(ref exprs) => {
1886                 self.print_expr_tup(&exprs[..], attrs);
1887             }
1888             ast::ExprKind::Call(ref func, ref args) => {
1889                 self.print_expr_call(func, &args[..]);
1890             }
1891             ast::ExprKind::MethodCall(ref segment, ref args) => {
1892                 self.print_expr_method_call(segment, &args[..]);
1893             }
1894             ast::ExprKind::Binary(op, ref lhs, ref rhs) => {
1895                 self.print_expr_binary(op, lhs, rhs);
1896             }
1897             ast::ExprKind::Unary(op, ref expr) => {
1898                 self.print_expr_unary(op, expr);
1899             }
1900             ast::ExprKind::AddrOf(k, m, ref expr) => {
1901                 self.print_expr_addr_of(k, m, expr);
1902             }
1903             ast::ExprKind::Lit(ref lit) => {
1904                 self.print_literal(lit);
1905             }
1906             ast::ExprKind::Cast(ref expr, ref ty) => {
1907                 let prec = AssocOp::As.precedence() as i8;
1908                 self.print_expr_maybe_paren(expr, prec);
1909                 self.s.space();
1910                 self.word_space("as");
1911                 self.print_type(ty);
1912             }
1913             ast::ExprKind::Type(ref expr, ref ty) => {
1914                 let prec = AssocOp::Colon.precedence() as i8;
1915                 self.print_expr_maybe_paren(expr, prec);
1916                 self.word_space(":");
1917                 self.print_type(ty);
1918             }
1919             ast::ExprKind::Let(ref pat, ref scrutinee) => {
1920                 self.print_let(pat, scrutinee);
1921             }
1922             ast::ExprKind::If(ref test, ref blk, ref elseopt) => {
1923                 self.print_if(test, blk, elseopt.as_deref())
1924             }
1925             ast::ExprKind::While(ref test, ref blk, opt_label) => {
1926                 if let Some(label) = opt_label {
1927                     self.print_ident(label.ident);
1928                     self.word_space(":");
1929                 }
1930                 self.head("while");
1931                 self.print_expr_as_cond(test);
1932                 self.s.space();
1933                 self.print_block_with_attrs(blk, attrs);
1934             }
1935             ast::ExprKind::ForLoop(ref pat, ref iter, ref blk, opt_label) => {
1936                 if let Some(label) = opt_label {
1937                     self.print_ident(label.ident);
1938                     self.word_space(":");
1939                 }
1940                 self.head("for");
1941                 self.print_pat(pat);
1942                 self.s.space();
1943                 self.word_space("in");
1944                 self.print_expr_as_cond(iter);
1945                 self.s.space();
1946                 self.print_block_with_attrs(blk, attrs);
1947             }
1948             ast::ExprKind::Loop(ref blk, opt_label) => {
1949                 if let Some(label) = opt_label {
1950                     self.print_ident(label.ident);
1951                     self.word_space(":");
1952                 }
1953                 self.head("loop");
1954                 self.s.space();
1955                 self.print_block_with_attrs(blk, attrs);
1956             }
1957             ast::ExprKind::Match(ref expr, ref arms) => {
1958                 self.cbox(INDENT_UNIT);
1959                 self.ibox(INDENT_UNIT);
1960                 self.word_nbsp("match");
1961                 self.print_expr_as_cond(expr);
1962                 self.s.space();
1963                 self.bopen();
1964                 self.print_inner_attributes_no_trailing_hardbreak(attrs);
1965                 for arm in arms {
1966                     self.print_arm(arm);
1967                 }
1968                 self.bclose(expr.span);
1969             }
1970             ast::ExprKind::Closure(
1971                 capture_clause,
1972                 asyncness,
1973                 movability,
1974                 ref decl,
1975                 ref body,
1976                 _,
1977             ) => {
1978                 self.print_movability(movability);
1979                 self.print_asyncness(asyncness);
1980                 self.print_capture_clause(capture_clause);
1981
1982                 self.print_fn_params_and_ret(decl, true);
1983                 self.s.space();
1984                 self.print_expr(body);
1985                 self.end(); // need to close a box
1986
1987                 // a box will be closed by print_expr, but we didn't want an overall
1988                 // wrapper so we closed the corresponding opening. so create an
1989                 // empty box to satisfy the close.
1990                 self.ibox(0);
1991             }
1992             ast::ExprKind::Block(ref blk, opt_label) => {
1993                 if let Some(label) = opt_label {
1994                     self.print_ident(label.ident);
1995                     self.word_space(":");
1996                 }
1997                 // containing cbox, will be closed by print-block at }
1998                 self.cbox(INDENT_UNIT);
1999                 // head-box, will be closed by print-block after {
2000                 self.ibox(0);
2001                 self.print_block_with_attrs(blk, attrs);
2002             }
2003             ast::ExprKind::Async(capture_clause, _, ref blk) => {
2004                 self.word_nbsp("async");
2005                 self.print_capture_clause(capture_clause);
2006                 self.s.space();
2007                 // cbox/ibox in analogy to the `ExprKind::Block` arm above
2008                 self.cbox(INDENT_UNIT);
2009                 self.ibox(0);
2010                 self.print_block_with_attrs(blk, attrs);
2011             }
2012             ast::ExprKind::Await(ref expr) => {
2013                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2014                 self.s.word(".await");
2015             }
2016             ast::ExprKind::Assign(ref lhs, ref rhs, _) => {
2017                 let prec = AssocOp::Assign.precedence() as i8;
2018                 self.print_expr_maybe_paren(lhs, prec + 1);
2019                 self.s.space();
2020                 self.word_space("=");
2021                 self.print_expr_maybe_paren(rhs, prec);
2022             }
2023             ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
2024                 let prec = AssocOp::Assign.precedence() as i8;
2025                 self.print_expr_maybe_paren(lhs, prec + 1);
2026                 self.s.space();
2027                 self.s.word(op.node.to_string());
2028                 self.word_space("=");
2029                 self.print_expr_maybe_paren(rhs, prec);
2030             }
2031             ast::ExprKind::Field(ref expr, ident) => {
2032                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2033                 self.s.word(".");
2034                 self.print_ident(ident);
2035             }
2036             ast::ExprKind::Index(ref expr, ref index) => {
2037                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
2038                 self.s.word("[");
2039                 self.print_expr(index);
2040                 self.s.word("]");
2041             }
2042             ast::ExprKind::Range(ref start, ref end, limits) => {
2043                 // Special case for `Range`.  `AssocOp` claims that `Range` has higher precedence
2044                 // than `Assign`, but `x .. x = x` gives a parse error instead of `x .. (x = x)`.
2045                 // Here we use a fake precedence value so that any child with lower precedence than
2046                 // a "normal" binop gets parenthesized.  (`LOr` is the lowest-precedence binop.)
2047                 let fake_prec = AssocOp::LOr.precedence() as i8;
2048                 if let Some(ref e) = *start {
2049                     self.print_expr_maybe_paren(e, fake_prec);
2050                 }
2051                 if limits == ast::RangeLimits::HalfOpen {
2052                     self.s.word("..");
2053                 } else {
2054                     self.s.word("..=");
2055                 }
2056                 if let Some(ref e) = *end {
2057                     self.print_expr_maybe_paren(e, fake_prec);
2058                 }
2059             }
2060             ast::ExprKind::Path(None, ref path) => self.print_path(path, true, 0),
2061             ast::ExprKind::Path(Some(ref qself), ref path) => self.print_qpath(path, qself, true),
2062             ast::ExprKind::Break(opt_label, ref opt_expr) => {
2063                 self.s.word("break");
2064                 self.s.space();
2065                 if let Some(label) = opt_label {
2066                     self.print_ident(label.ident);
2067                     self.s.space();
2068                 }
2069                 if let Some(ref expr) = *opt_expr {
2070                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2071                     self.s.space();
2072                 }
2073             }
2074             ast::ExprKind::Continue(opt_label) => {
2075                 self.s.word("continue");
2076                 self.s.space();
2077                 if let Some(label) = opt_label {
2078                     self.print_ident(label.ident);
2079                     self.s.space()
2080                 }
2081             }
2082             ast::ExprKind::Ret(ref result) => {
2083                 self.s.word("return");
2084                 if let Some(ref expr) = *result {
2085                     self.s.word(" ");
2086                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2087                 }
2088             }
2089             ast::ExprKind::InlineAsm(ref a) => {
2090                 self.s.word("asm!");
2091                 self.popen();
2092                 self.print_string(&a.asm.as_str(), a.asm_str_style);
2093                 self.word_space(":");
2094
2095                 self.commasep(Inconsistent, &a.outputs, |s, out| {
2096                     let constraint = out.constraint.as_str();
2097                     let mut ch = constraint.chars();
2098                     match ch.next() {
2099                         Some('=') if out.is_rw => {
2100                             s.print_string(&format!("+{}", ch.as_str()), ast::StrStyle::Cooked)
2101                         }
2102                         _ => s.print_string(&constraint, ast::StrStyle::Cooked),
2103                     }
2104                     s.popen();
2105                     s.print_expr(&out.expr);
2106                     s.pclose();
2107                 });
2108                 self.s.space();
2109                 self.word_space(":");
2110
2111                 self.commasep(Inconsistent, &a.inputs, |s, &(co, ref o)| {
2112                     s.print_string(&co.as_str(), ast::StrStyle::Cooked);
2113                     s.popen();
2114                     s.print_expr(o);
2115                     s.pclose();
2116                 });
2117                 self.s.space();
2118                 self.word_space(":");
2119
2120                 self.commasep(Inconsistent, &a.clobbers, |s, co| {
2121                     s.print_string(&co.as_str(), ast::StrStyle::Cooked);
2122                 });
2123
2124                 let mut options = vec![];
2125                 if a.volatile {
2126                     options.push("volatile");
2127                 }
2128                 if a.alignstack {
2129                     options.push("alignstack");
2130                 }
2131                 if a.dialect == ast::AsmDialect::Intel {
2132                     options.push("intel");
2133                 }
2134
2135                 if !options.is_empty() {
2136                     self.s.space();
2137                     self.word_space(":");
2138                     self.commasep(Inconsistent, &options, |s, &co| {
2139                         s.print_string(co, ast::StrStyle::Cooked);
2140                     });
2141                 }
2142
2143                 self.pclose();
2144             }
2145             ast::ExprKind::Mac(ref m) => self.print_mac(m),
2146             ast::ExprKind::Paren(ref e) => {
2147                 self.popen();
2148                 self.print_inner_attributes_inline(attrs);
2149                 self.print_expr(e);
2150                 self.pclose();
2151             }
2152             ast::ExprKind::Yield(ref e) => {
2153                 self.s.word("yield");
2154                 match *e {
2155                     Some(ref expr) => {
2156                         self.s.space();
2157                         self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
2158                     }
2159                     _ => (),
2160                 }
2161             }
2162             ast::ExprKind::Try(ref e) => {
2163                 self.print_expr_maybe_paren(e, parser::PREC_POSTFIX);
2164                 self.s.word("?")
2165             }
2166             ast::ExprKind::TryBlock(ref blk) => {
2167                 self.head("try");
2168                 self.s.space();
2169                 self.print_block_with_attrs(blk, attrs)
2170             }
2171             ast::ExprKind::Err => {
2172                 self.popen();
2173                 self.s.word("/*ERROR*/");
2174                 self.pclose()
2175             }
2176         }
2177         self.ann.post(self, AnnNode::Expr(expr));
2178         self.end();
2179     }
2180
2181     crate fn print_local_decl(&mut self, loc: &ast::Local) {
2182         self.print_pat(&loc.pat);
2183         if let Some(ref ty) = loc.ty {
2184             self.word_space(":");
2185             self.print_type(ty);
2186         }
2187     }
2188
2189     pub fn print_usize(&mut self, i: usize) {
2190         self.s.word(i.to_string())
2191     }
2192
2193     crate fn print_name(&mut self, name: ast::Name) {
2194         self.s.word(name.to_string());
2195         self.ann.post(self, AnnNode::Name(&name))
2196     }
2197
2198     fn print_qpath(&mut self, path: &ast::Path, qself: &ast::QSelf, colons_before_params: bool) {
2199         self.s.word("<");
2200         self.print_type(&qself.ty);
2201         if qself.position > 0 {
2202             self.s.space();
2203             self.word_space("as");
2204             let depth = path.segments.len() - qself.position;
2205             self.print_path(path, false, depth);
2206         }
2207         self.s.word(">");
2208         self.s.word("::");
2209         let item_segment = path.segments.last().unwrap();
2210         self.print_ident(item_segment.ident);
2211         match item_segment.args {
2212             Some(ref args) => self.print_generic_args(args, colons_before_params),
2213             None => {}
2214         }
2215     }
2216
2217     crate fn print_pat(&mut self, pat: &ast::Pat) {
2218         self.maybe_print_comment(pat.span.lo());
2219         self.ann.pre(self, AnnNode::Pat(pat));
2220         /* Pat isn't normalized, but the beauty of it
2221         is that it doesn't matter */
2222         match pat.kind {
2223             PatKind::Wild => self.s.word("_"),
2224             PatKind::Ident(binding_mode, ident, ref sub) => {
2225                 match binding_mode {
2226                     ast::BindingMode::ByRef(mutbl) => {
2227                         self.word_nbsp("ref");
2228                         self.print_mutability(mutbl, false);
2229                     }
2230                     ast::BindingMode::ByValue(ast::Mutability::Not) => {}
2231                     ast::BindingMode::ByValue(ast::Mutability::Mut) => {
2232                         self.word_nbsp("mut");
2233                     }
2234                 }
2235                 self.print_ident(ident);
2236                 if let Some(ref p) = *sub {
2237                     self.s.space();
2238                     self.s.word_space("@");
2239                     self.print_pat(p);
2240                 }
2241             }
2242             PatKind::TupleStruct(ref path, ref elts) => {
2243                 self.print_path(path, true, 0);
2244                 self.popen();
2245                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2246                 self.pclose();
2247             }
2248             PatKind::Or(ref pats) => {
2249                 self.strsep("|", true, Inconsistent, &pats[..], |s, p| s.print_pat(p));
2250             }
2251             PatKind::Path(None, ref path) => {
2252                 self.print_path(path, true, 0);
2253             }
2254             PatKind::Path(Some(ref qself), ref path) => {
2255                 self.print_qpath(path, qself, false);
2256             }
2257             PatKind::Struct(ref path, ref fields, etc) => {
2258                 self.print_path(path, true, 0);
2259                 self.nbsp();
2260                 self.word_space("{");
2261                 self.commasep_cmnt(
2262                     Consistent,
2263                     &fields[..],
2264                     |s, f| {
2265                         s.cbox(INDENT_UNIT);
2266                         if !f.is_shorthand {
2267                             s.print_ident(f.ident);
2268                             s.word_nbsp(":");
2269                         }
2270                         s.print_pat(&f.pat);
2271                         s.end();
2272                     },
2273                     |f| f.pat.span,
2274                 );
2275                 if etc {
2276                     if !fields.is_empty() {
2277                         self.word_space(",");
2278                     }
2279                     self.s.word("..");
2280                 }
2281                 self.s.space();
2282                 self.s.word("}");
2283             }
2284             PatKind::Tuple(ref elts) => {
2285                 self.popen();
2286                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2287                 if elts.len() == 1 {
2288                     self.s.word(",");
2289                 }
2290                 self.pclose();
2291             }
2292             PatKind::Box(ref inner) => {
2293                 self.s.word("box ");
2294                 self.print_pat(inner);
2295             }
2296             PatKind::Ref(ref inner, mutbl) => {
2297                 self.s.word("&");
2298                 if mutbl == ast::Mutability::Mut {
2299                     self.s.word("mut ");
2300                 }
2301                 self.print_pat(inner);
2302             }
2303             PatKind::Lit(ref e) => self.print_expr(&**e),
2304             PatKind::Range(ref begin, ref end, Spanned { node: ref end_kind, .. }) => {
2305                 if let Some(e) = begin {
2306                     self.print_expr(e);
2307                     self.s.space();
2308                 }
2309                 match *end_kind {
2310                     RangeEnd::Included(RangeSyntax::DotDotDot) => self.s.word("..."),
2311                     RangeEnd::Included(RangeSyntax::DotDotEq) => self.s.word("..="),
2312                     RangeEnd::Excluded => self.s.word(".."),
2313                 }
2314                 if let Some(e) = end {
2315                     self.print_expr(e);
2316                 }
2317             }
2318             PatKind::Slice(ref elts) => {
2319                 self.s.word("[");
2320                 self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(p));
2321                 self.s.word("]");
2322             }
2323             PatKind::Rest => self.s.word(".."),
2324             PatKind::Paren(ref inner) => {
2325                 self.popen();
2326                 self.print_pat(inner);
2327                 self.pclose();
2328             }
2329             PatKind::Mac(ref m) => self.print_mac(m),
2330         }
2331         self.ann.post(self, AnnNode::Pat(pat))
2332     }
2333
2334     fn print_arm(&mut self, arm: &ast::Arm) {
2335         // Note, I have no idea why this check is necessary, but here it is.
2336         if arm.attrs.is_empty() {
2337             self.s.space();
2338         }
2339         self.cbox(INDENT_UNIT);
2340         self.ibox(0);
2341         self.maybe_print_comment(arm.pat.span.lo());
2342         self.print_outer_attributes(&arm.attrs);
2343         self.print_pat(&arm.pat);
2344         self.s.space();
2345         if let Some(ref e) = arm.guard {
2346             self.word_space("if");
2347             self.print_expr(e);
2348             self.s.space();
2349         }
2350         self.word_space("=>");
2351
2352         match arm.body.kind {
2353             ast::ExprKind::Block(ref blk, opt_label) => {
2354                 if let Some(label) = opt_label {
2355                     self.print_ident(label.ident);
2356                     self.word_space(":");
2357                 }
2358
2359                 // The block will close the pattern's ibox.
2360                 self.print_block_unclosed_indent(blk);
2361
2362                 // If it is a user-provided unsafe block, print a comma after it.
2363                 if let BlockCheckMode::Unsafe(ast::UserProvided) = blk.rules {
2364                     self.s.word(",");
2365                 }
2366             }
2367             _ => {
2368                 self.end(); // Close the ibox for the pattern.
2369                 self.print_expr(&arm.body);
2370                 self.s.word(",");
2371             }
2372         }
2373         self.end(); // Close enclosing cbox.
2374     }
2375
2376     fn print_explicit_self(&mut self, explicit_self: &ast::ExplicitSelf) {
2377         match explicit_self.node {
2378             SelfKind::Value(m) => {
2379                 self.print_mutability(m, false);
2380                 self.s.word("self")
2381             }
2382             SelfKind::Region(ref lt, m) => {
2383                 self.s.word("&");
2384                 self.print_opt_lifetime(lt);
2385                 self.print_mutability(m, false);
2386                 self.s.word("self")
2387             }
2388             SelfKind::Explicit(ref typ, m) => {
2389                 self.print_mutability(m, false);
2390                 self.s.word("self");
2391                 self.word_space(":");
2392                 self.print_type(typ)
2393             }
2394         }
2395     }
2396
2397     fn print_fn_full(
2398         &mut self,
2399         sig: &ast::FnSig,
2400         name: ast::Ident,
2401         generics: &ast::Generics,
2402         vis: &ast::Visibility,
2403         body: Option<&ast::Block>,
2404         attrs: &[ast::Attribute],
2405     ) {
2406         if body.is_some() {
2407             self.head("");
2408         }
2409         self.print_fn(&sig.decl, sig.header, Some(name), generics, vis);
2410         if let Some(body) = body {
2411             self.nbsp();
2412             self.print_block_with_attrs(body, attrs);
2413         } else {
2414             self.s.word(";");
2415         }
2416     }
2417
2418     crate fn print_fn(
2419         &mut self,
2420         decl: &ast::FnDecl,
2421         header: ast::FnHeader,
2422         name: Option<ast::Ident>,
2423         generics: &ast::Generics,
2424         vis: &ast::Visibility,
2425     ) {
2426         self.print_fn_header_info(header, vis);
2427
2428         if let Some(name) = name {
2429             self.nbsp();
2430             self.print_ident(name);
2431         }
2432         self.print_generic_params(&generics.params);
2433         self.print_fn_params_and_ret(decl, false);
2434         self.print_where_clause(&generics.where_clause)
2435     }
2436
2437     crate fn print_fn_params_and_ret(&mut self, decl: &ast::FnDecl, is_closure: bool) {
2438         let (open, close) = if is_closure { ("|", "|") } else { ("(", ")") };
2439         self.word(open);
2440         self.commasep(Inconsistent, &decl.inputs, |s, param| s.print_param(param, is_closure));
2441         self.word(close);
2442         self.print_fn_ret_ty(&decl.output)
2443     }
2444
2445     crate fn print_movability(&mut self, movability: ast::Movability) {
2446         match movability {
2447             ast::Movability::Static => self.word_space("static"),
2448             ast::Movability::Movable => {}
2449         }
2450     }
2451
2452     crate fn print_asyncness(&mut self, asyncness: ast::IsAsync) {
2453         if asyncness.is_async() {
2454             self.word_nbsp("async");
2455         }
2456     }
2457
2458     crate fn print_capture_clause(&mut self, capture_clause: ast::CaptureBy) {
2459         match capture_clause {
2460             ast::CaptureBy::Value => self.word_space("move"),
2461             ast::CaptureBy::Ref => {}
2462         }
2463     }
2464
2465     pub fn print_type_bounds(&mut self, prefix: &'static str, bounds: &[ast::GenericBound]) {
2466         if !bounds.is_empty() {
2467             self.s.word(prefix);
2468             let mut first = true;
2469             for bound in bounds {
2470                 if !(first && prefix.is_empty()) {
2471                     self.nbsp();
2472                 }
2473                 if first {
2474                     first = false;
2475                 } else {
2476                     self.word_space("+");
2477                 }
2478
2479                 match bound {
2480                     GenericBound::Trait(tref, modifier) => {
2481                         if modifier == &TraitBoundModifier::Maybe {
2482                             self.s.word("?");
2483                         }
2484                         self.print_poly_trait_ref(tref);
2485                     }
2486                     GenericBound::Outlives(lt) => self.print_lifetime(*lt),
2487                 }
2488             }
2489         }
2490     }
2491
2492     crate fn print_lifetime(&mut self, lifetime: ast::Lifetime) {
2493         self.print_name(lifetime.ident.name)
2494     }
2495
2496     crate fn print_lifetime_bounds(
2497         &mut self,
2498         lifetime: ast::Lifetime,
2499         bounds: &ast::GenericBounds,
2500     ) {
2501         self.print_lifetime(lifetime);
2502         if !bounds.is_empty() {
2503             self.s.word(": ");
2504             for (i, bound) in bounds.iter().enumerate() {
2505                 if i != 0 {
2506                     self.s.word(" + ");
2507                 }
2508                 match bound {
2509                     ast::GenericBound::Outlives(lt) => self.print_lifetime(*lt),
2510                     _ => panic!(),
2511                 }
2512             }
2513         }
2514     }
2515
2516     crate fn print_generic_params(&mut self, generic_params: &[ast::GenericParam]) {
2517         if generic_params.is_empty() {
2518             return;
2519         }
2520
2521         self.s.word("<");
2522
2523         self.commasep(Inconsistent, &generic_params, |s, param| {
2524             s.print_outer_attributes_inline(&param.attrs);
2525
2526             match param.kind {
2527                 ast::GenericParamKind::Lifetime => {
2528                     let lt = ast::Lifetime { id: param.id, ident: param.ident };
2529                     s.print_lifetime_bounds(lt, &param.bounds)
2530                 }
2531                 ast::GenericParamKind::Type { ref default } => {
2532                     s.print_ident(param.ident);
2533                     s.print_type_bounds(":", &param.bounds);
2534                     if let Some(ref default) = default {
2535                         s.s.space();
2536                         s.word_space("=");
2537                         s.print_type(default)
2538                     }
2539                 }
2540                 ast::GenericParamKind::Const { ref ty } => {
2541                     s.word_space("const");
2542                     s.print_ident(param.ident);
2543                     s.s.space();
2544                     s.word_space(":");
2545                     s.print_type(ty);
2546                     s.print_type_bounds(":", &param.bounds)
2547                 }
2548             }
2549         });
2550
2551         self.s.word(">");
2552     }
2553
2554     crate fn print_where_clause(&mut self, where_clause: &ast::WhereClause) {
2555         if where_clause.predicates.is_empty() {
2556             return;
2557         }
2558
2559         self.s.space();
2560         self.word_space("where");
2561
2562         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2563             if i != 0 {
2564                 self.word_space(",");
2565             }
2566
2567             match *predicate {
2568                 ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
2569                     ref bound_generic_params,
2570                     ref bounded_ty,
2571                     ref bounds,
2572                     ..
2573                 }) => {
2574                     self.print_formal_generic_params(bound_generic_params);
2575                     self.print_type(bounded_ty);
2576                     self.print_type_bounds(":", bounds);
2577                 }
2578                 ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
2579                     ref lifetime,
2580                     ref bounds,
2581                     ..
2582                 }) => {
2583                     self.print_lifetime_bounds(*lifetime, bounds);
2584                 }
2585                 ast::WherePredicate::EqPredicate(ast::WhereEqPredicate {
2586                     ref lhs_ty,
2587                     ref rhs_ty,
2588                     ..
2589                 }) => {
2590                     self.print_type(lhs_ty);
2591                     self.s.space();
2592                     self.word_space("=");
2593                     self.print_type(rhs_ty);
2594                 }
2595             }
2596         }
2597     }
2598
2599     crate fn print_use_tree(&mut self, tree: &ast::UseTree) {
2600         match tree.kind {
2601             ast::UseTreeKind::Simple(rename, ..) => {
2602                 self.print_path(&tree.prefix, false, 0);
2603                 if let Some(rename) = rename {
2604                     self.s.space();
2605                     self.word_space("as");
2606                     self.print_ident(rename);
2607                 }
2608             }
2609             ast::UseTreeKind::Glob => {
2610                 if !tree.prefix.segments.is_empty() {
2611                     self.print_path(&tree.prefix, false, 0);
2612                     self.s.word("::");
2613                 }
2614                 self.s.word("*");
2615             }
2616             ast::UseTreeKind::Nested(ref items) => {
2617                 if tree.prefix.segments.is_empty() {
2618                     self.s.word("{");
2619                 } else {
2620                     self.print_path(&tree.prefix, false, 0);
2621                     self.s.word("::{");
2622                 }
2623                 self.commasep(Inconsistent, &items[..], |this, &(ref tree, _)| {
2624                     this.print_use_tree(tree)
2625                 });
2626                 self.s.word("}");
2627             }
2628         }
2629     }
2630
2631     pub fn print_mutability(&mut self, mutbl: ast::Mutability, print_const: bool) {
2632         match mutbl {
2633             ast::Mutability::Mut => self.word_nbsp("mut"),
2634             ast::Mutability::Not => {
2635                 if print_const {
2636                     self.word_nbsp("const");
2637                 }
2638             }
2639         }
2640     }
2641
2642     crate fn print_mt(&mut self, mt: &ast::MutTy, print_const: bool) {
2643         self.print_mutability(mt.mutbl, print_const);
2644         self.print_type(&mt.ty)
2645     }
2646
2647     crate fn print_param(&mut self, input: &ast::Param, is_closure: bool) {
2648         self.ibox(INDENT_UNIT);
2649
2650         self.print_outer_attributes_inline(&input.attrs);
2651
2652         match input.ty.kind {
2653             ast::TyKind::Infer if is_closure => self.print_pat(&input.pat),
2654             _ => {
2655                 if let Some(eself) = input.to_self() {
2656                     self.print_explicit_self(&eself);
2657                 } else {
2658                     let invalid = if let PatKind::Ident(_, ident, _) = input.pat.kind {
2659                         ident.name == kw::Invalid
2660                     } else {
2661                         false
2662                     };
2663                     if !invalid {
2664                         self.print_pat(&input.pat);
2665                         self.s.word(":");
2666                         self.s.space();
2667                     }
2668                     self.print_type(&input.ty);
2669                 }
2670             }
2671         }
2672         self.end();
2673     }
2674
2675     crate fn print_fn_ret_ty(&mut self, fn_ret_ty: &ast::FunctionRetTy) {
2676         if let ast::FunctionRetTy::Ty(ty) = fn_ret_ty {
2677             self.space_if_not_bol();
2678             self.ibox(INDENT_UNIT);
2679             self.word_space("->");
2680             self.print_type(ty);
2681             self.end();
2682             self.maybe_print_comment(ty.span.lo());
2683         }
2684     }
2685
2686     crate fn print_ty_fn(
2687         &mut self,
2688         ext: ast::Extern,
2689         unsafety: ast::Unsafety,
2690         decl: &ast::FnDecl,
2691         name: Option<ast::Ident>,
2692         generic_params: &[ast::GenericParam],
2693     ) {
2694         self.ibox(INDENT_UNIT);
2695         if !generic_params.is_empty() {
2696             self.s.word("for");
2697             self.print_generic_params(generic_params);
2698         }
2699         let generics = ast::Generics {
2700             params: Vec::new(),
2701             where_clause: ast::WhereClause { predicates: Vec::new(), span: rustc_span::DUMMY_SP },
2702             span: rustc_span::DUMMY_SP,
2703         };
2704         let header = ast::FnHeader { unsafety, ext, ..ast::FnHeader::default() };
2705         let vis = dummy_spanned(ast::VisibilityKind::Inherited);
2706         self.print_fn(decl, header, name, &generics, &vis);
2707         self.end();
2708     }
2709
2710     crate fn maybe_print_trailing_comment(
2711         &mut self,
2712         span: rustc_span::Span,
2713         next_pos: Option<BytePos>,
2714     ) {
2715         if let Some(cmnts) = self.comments() {
2716             if let Some(cmnt) = cmnts.trailing_comment(span, next_pos) {
2717                 self.print_comment(&cmnt);
2718             }
2719         }
2720     }
2721
2722     crate fn print_remaining_comments(&mut self) {
2723         // If there aren't any remaining comments, then we need to manually
2724         // make sure there is a line break at the end.
2725         if self.next_comment().is_none() {
2726             self.s.hardbreak();
2727         }
2728         while let Some(ref cmnt) = self.next_comment() {
2729             self.print_comment(cmnt);
2730         }
2731     }
2732
2733     crate fn print_fn_header_info(&mut self, header: ast::FnHeader, vis: &ast::Visibility) {
2734         self.s.word(visibility_qualified(vis, ""));
2735
2736         match header.constness.node {
2737             ast::Constness::NotConst => {}
2738             ast::Constness::Const => self.word_nbsp("const"),
2739         }
2740
2741         self.print_asyncness(header.asyncness.node);
2742         self.print_unsafety(header.unsafety);
2743
2744         match header.ext {
2745             ast::Extern::None => {}
2746             ast::Extern::Implicit => {
2747                 self.word_nbsp("extern");
2748             }
2749             ast::Extern::Explicit(abi) => {
2750                 self.word_nbsp("extern");
2751                 self.print_literal(&abi.as_lit());
2752                 self.nbsp();
2753             }
2754         }
2755
2756         self.s.word("fn")
2757     }
2758
2759     crate fn print_unsafety(&mut self, s: ast::Unsafety) {
2760         match s {
2761             ast::Unsafety::Normal => {}
2762             ast::Unsafety::Unsafe => self.word_nbsp("unsafe"),
2763         }
2764     }
2765
2766     crate fn print_constness(&mut self, s: ast::Constness) {
2767         match s {
2768             ast::Constness::Const => self.word_nbsp("const"),
2769             ast::Constness::NotConst => {}
2770         }
2771     }
2772
2773     crate fn print_is_auto(&mut self, s: ast::IsAuto) {
2774         match s {
2775             ast::IsAuto::Yes => self.word_nbsp("auto"),
2776             ast::IsAuto::No => {}
2777         }
2778     }
2779 }