src/librustdoc/html/format.rs

   1 //! HTML formatting module
   2 //!
   3 //! This module contains a large number of `fmt::Display` implementations for
   4 //! various types in `rustdoc::clean`. These implementations all currently
   5 //! assume that HTML output is desired, although it may be possible to redesign
   6 //! them in the future to instead emit any format desired.
   7
   8 use std::cell::Cell;
   9 use std::fmt;
  10 use std::iter;
  11
  12 use rustc_data_structures::captures::Captures;
  13 use rustc_data_structures::fx::FxHashSet;
  14 use rustc_hir as hir;
  15 use rustc_hir::def_id::DefId;
  16 use rustc_middle::ty::TyCtxt;
  17 use rustc_span::def_id::CRATE_DEF_INDEX;
  18 use rustc_target::spec::abi::Abi;
  19
  20 use crate::clean::{
  21     self, utils::find_nearest_parent_module, ExternalCrate, FakeDefId, GetDefId, PrimitiveType,
  22 };
  23 use crate::formats::item_type::ItemType;
  24 use crate::html::escape::Escape;
  25 use crate::html::render::cache::ExternalLocation;
  26 use crate::html::render::Context;
  27
  28 crate trait Print {
  29     fn print(self, buffer: &mut Buffer);
  30 }
  31
  32 impl<F> Print for F
  33 where
  34     F: FnOnce(&mut Buffer),
  35 {
  36     fn print(self, buffer: &mut Buffer) {
  37         (self)(buffer)
  38     }
  39 }
  40
  41 impl Print for String {
  42     fn print(self, buffer: &mut Buffer) {
  43         buffer.write_str(&self);
  44     }
  45 }
  46
  47 impl Print for &'_ str {
  48     fn print(self, buffer: &mut Buffer) {
  49         buffer.write_str(self);
  50     }
  51 }
  52
  53 #[derive(Debug, Clone)]
  54 crate struct Buffer {
  55     for_html: bool,
  56     buffer: String,
  57 }
  58
  59 impl Buffer {
  60     crate fn empty_from(v: &Buffer) -> Buffer {
  61         Buffer { for_html: v.for_html, buffer: String::new() }
  62     }
  63
  64     crate fn html() -> Buffer {
  65         Buffer { for_html: true, buffer: String::new() }
  66     }
  67
  68     crate fn new() -> Buffer {
  69         Buffer { for_html: false, buffer: String::new() }
  70     }
  71
  72     crate fn is_empty(&self) -> bool {
  73         self.buffer.is_empty()
  74     }
  75
  76     crate fn into_inner(self) -> String {
  77         self.buffer
  78     }
  79
  80     crate fn insert_str(&mut self, idx: usize, s: &str) {
  81         self.buffer.insert_str(idx, s);
  82     }
  83
  84     crate fn push_str(&mut self, s: &str) {
  85         self.buffer.push_str(s);
  86     }
  87
  88     crate fn push_buffer(&mut self, other: Buffer) {
  89         self.buffer.push_str(&other.buffer);
  90     }
  91
  92     // Intended for consumption by write! and writeln! (std::fmt) but without
  93     // the fmt::Result return type imposed by fmt::Write (and avoiding the trait
  94     // import).
  95     crate fn write_str(&mut self, s: &str) {
  96         self.buffer.push_str(s);
  97     }
  98
  99     // Intended for consumption by write! and writeln! (std::fmt) but without
 100     // the fmt::Result return type imposed by fmt::Write (and avoiding the trait
 101     // import).
 102     crate fn write_fmt(&mut self, v: fmt::Arguments<'_>) {
 103         use fmt::Write;
 104         self.buffer.write_fmt(v).unwrap();
 105     }
 106
 107     crate fn to_display<T: Print>(mut self, t: T) -> String {
 108         t.print(&mut self);
 109         self.into_inner()
 110     }
 111
 112     crate fn is_for_html(&self) -> bool {
 113         self.for_html
 114     }
 115
 116     crate fn reserve(&mut self, additional: usize) {
 117         self.buffer.reserve(additional)
 118     }
 119 }
 120
 121 fn comma_sep<T: fmt::Display>(items: impl Iterator<Item = T>) -> impl fmt::Display {
 122     display_fn(move |f| {
 123         for (i, item) in items.enumerate() {
 124             if i != 0 {
 125                 write!(f, ", ")?;
 126             }
 127             fmt::Display::fmt(&item, f)?;
 128         }
 129         Ok(())
 130     })
 131 }
 132
 133 crate fn print_generic_bounds<'a, 'tcx: 'a>(
 134     bounds: &'a [clean::GenericBound],
 135     cx: &'a Context<'tcx>,
 136 ) -> impl fmt::Display + 'a + Captures<'tcx> {
 137     display_fn(move |f| {
 138         let mut bounds_dup = FxHashSet::default();
 139
 140         for (i, bound) in
 141             bounds.iter().filter(|b| bounds_dup.insert(b.print(cx).to_string())).enumerate()
 142         {
 143             if i > 0 {
 144                 f.write_str(" + ")?;
 145             }
 146             fmt::Display::fmt(&bound.print(cx), f)?;
 147         }
 148         Ok(())
 149     })
 150 }
 151
 152 impl clean::GenericParamDef {
 153     crate fn print<'a, 'tcx: 'a>(
 154         &'a self,
 155         cx: &'a Context<'tcx>,
 156     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 157         display_fn(move |f| match self.kind {
 158             clean::GenericParamDefKind::Lifetime => write!(f, "{}", self.name),
 159             clean::GenericParamDefKind::Type { ref bounds, ref default, .. } => {
 160                 f.write_str(&*self.name.as_str())?;
 161
 162                 if !bounds.is_empty() {
 163                     if f.alternate() {
 164                         write!(f, ": {:#}", print_generic_bounds(bounds, cx))?;
 165                     } else {
 166                         write!(f, ":&nbsp;{}", print_generic_bounds(bounds, cx))?;
 167                     }
 168                 }
 169
 170                 if let Some(ref ty) = default {
 171                     if f.alternate() {
 172                         write!(f, " = {:#}", ty.print(cx))?;
 173                     } else {
 174                         write!(f, "&nbsp;=&nbsp;{}", ty.print(cx))?;
 175                     }
 176                 }
 177
 178                 Ok(())
 179             }
 180             clean::GenericParamDefKind::Const { ref ty, ref default, .. } => {
 181                 if f.alternate() {
 182                     write!(f, "const {}: {:#}", self.name, ty.print(cx))?;
 183                 } else {
 184                     write!(f, "const {}:&nbsp;{}", self.name, ty.print(cx))?;
 185                 }
 186
 187                 if let Some(default) = default {
 188                     if f.alternate() {
 189                         write!(f, " = {:#}", default)?;
 190                     } else {
 191                         write!(f, "&nbsp;=&nbsp;{}", default)?;
 192                     }
 193                 }
 194
 195                 Ok(())
 196             }
 197         })
 198     }
 199 }
 200
 201 impl clean::Generics {
 202     crate fn print<'a, 'tcx: 'a>(
 203         &'a self,
 204         cx: &'a Context<'tcx>,
 205     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 206         display_fn(move |f| {
 207             let real_params =
 208                 self.params.iter().filter(|p| !p.is_synthetic_type_param()).collect::<Vec<_>>();
 209             if real_params.is_empty() {
 210                 return Ok(());
 211             }
 212             if f.alternate() {
 213                 write!(f, "<{:#}>", comma_sep(real_params.iter().map(|g| g.print(cx))))
 214             } else {
 215                 write!(f, "&lt;{}&gt;", comma_sep(real_params.iter().map(|g| g.print(cx))))
 216             }
 217         })
 218     }
 219 }
 220
 221 /// * The Generics from which to emit a where-clause.
 222 /// * The number of spaces to indent each line with.
 223 /// * Whether the where-clause needs to add a comma and newline after the last bound.
 224 crate fn print_where_clause<'a, 'tcx: 'a>(
 225     gens: &'a clean::Generics,
 226     cx: &'a Context<'tcx>,
 227     indent: usize,
 228     end_newline: bool,
 229 ) -> impl fmt::Display + 'a + Captures<'tcx> {
 230     display_fn(move |f| {
 231         if gens.where_predicates.is_empty() {
 232             return Ok(());
 233         }
 234         let mut clause = String::new();
 235         if f.alternate() {
 236             clause.push_str(" where");
 237         } else {
 238             if end_newline {
 239                 clause.push_str(" <span class=\"where fmt-newline\">where");
 240             } else {
 241                 clause.push_str(" <span class=\"where\">where");
 242             }
 243         }
 244         for (i, pred) in gens.where_predicates.iter().enumerate() {
 245             if f.alternate() {
 246                 clause.push(' ');
 247             } else {
 248                 clause.push_str("<br>");
 249             }
 250
 251             match pred {
 252                 clean::WherePredicate::BoundPredicate { ty, bounds } => {
 253                     let bounds = bounds;
 254                     if f.alternate() {
 255                         clause.push_str(&format!(
 256                             "{:#}: {:#}",
 257                             ty.print(cx),
 258                             print_generic_bounds(bounds, cx)
 259                         ));
 260                     } else {
 261                         clause.push_str(&format!(
 262                             "{}: {}",
 263                             ty.print(cx),
 264                             print_generic_bounds(bounds, cx)
 265                         ));
 266                     }
 267                 }
 268                 clean::WherePredicate::RegionPredicate { lifetime, bounds } => {
 269                     clause.push_str(&format!(
 270                         "{}: {}",
 271                         lifetime.print(),
 272                         bounds
 273                             .iter()
 274                             .map(|b| b.print(cx).to_string())
 275                             .collect::<Vec<_>>()
 276                             .join(" + ")
 277                     ));
 278                 }
 279                 clean::WherePredicate::EqPredicate { lhs, rhs } => {
 280                     if f.alternate() {
 281                         clause.push_str(&format!("{:#} == {:#}", lhs.print(cx), rhs.print(cx),));
 282                     } else {
 283                         clause.push_str(&format!("{} == {}", lhs.print(cx), rhs.print(cx),));
 284                     }
 285                 }
 286             }
 287
 288             if i < gens.where_predicates.len() - 1 || end_newline {
 289                 clause.push(',');
 290             }
 291         }
 292
 293         if end_newline {
 294             // add a space so stripping <br> tags and breaking spaces still renders properly
 295             if f.alternate() {
 296                 clause.push(' ');
 297             } else {
 298                 clause.push_str("&nbsp;");
 299             }
 300         }
 301
 302         if !f.alternate() {
 303             clause.push_str("</span>");
 304             let padding = "&nbsp;".repeat(indent + 4);
 305             clause = clause.replace("<br>", &format!("<br>{}", padding));
 306             clause.insert_str(0, &"&nbsp;".repeat(indent.saturating_sub(1)));
 307             if !end_newline {
 308                 clause.insert_str(0, "<br>");
 309             }
 310         }
 311         write!(f, "{}", clause)
 312     })
 313 }
 314
 315 impl clean::Lifetime {
 316     crate fn print(&self) -> impl fmt::Display + '_ {
 317         self.get_ref()
 318     }
 319 }
 320
 321 impl clean::Constant {
 322     crate fn print(&self, tcx: TyCtxt<'_>) -> impl fmt::Display + '_ {
 323         let expr = self.expr(tcx);
 324         display_fn(
 325             move |f| {
 326                 if f.alternate() { f.write_str(&expr) } else { write!(f, "{}", Escape(&expr)) }
 327             },
 328         )
 329     }
 330 }
 331
 332 impl clean::PolyTrait {
 333     fn print<'a, 'tcx: 'a>(
 334         &'a self,
 335         cx: &'a Context<'tcx>,
 336     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 337         display_fn(move |f| {
 338             if !self.generic_params.is_empty() {
 339                 if f.alternate() {
 340                     write!(
 341                         f,
 342                         "for<{:#}> ",
 343                         comma_sep(self.generic_params.iter().map(|g| g.print(cx)))
 344                     )?;
 345                 } else {
 346                     write!(
 347                         f,
 348                         "for&lt;{}&gt; ",
 349                         comma_sep(self.generic_params.iter().map(|g| g.print(cx)))
 350                     )?;
 351                 }
 352             }
 353             if f.alternate() {
 354                 write!(f, "{:#}", self.trait_.print(cx))
 355             } else {
 356                 write!(f, "{}", self.trait_.print(cx))
 357             }
 358         })
 359     }
 360 }
 361
 362 impl clean::GenericBound {
 363     crate fn print<'a, 'tcx: 'a>(
 364         &'a self,
 365         cx: &'a Context<'tcx>,
 366     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 367         display_fn(move |f| match self {
 368             clean::GenericBound::Outlives(lt) => write!(f, "{}", lt.print()),
 369             clean::GenericBound::TraitBound(ty, modifier) => {
 370                 let modifier_str = match modifier {
 371                     hir::TraitBoundModifier::None => "",
 372                     hir::TraitBoundModifier::Maybe => "?",
 373                     hir::TraitBoundModifier::MaybeConst => "?const",
 374                 };
 375                 if f.alternate() {
 376                     write!(f, "{}{:#}", modifier_str, ty.print(cx))
 377                 } else {
 378                     write!(f, "{}{}", modifier_str, ty.print(cx))
 379                 }
 380             }
 381         })
 382     }
 383 }
 384
 385 impl clean::GenericArgs {
 386     fn print<'a, 'tcx: 'a>(
 387         &'a self,
 388         cx: &'a Context<'tcx>,
 389     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 390         display_fn(move |f| {
 391             match self {
 392                 clean::GenericArgs::AngleBracketed { args, bindings } => {
 393                     if !args.is_empty() || !bindings.is_empty() {
 394                         if f.alternate() {
 395                             f.write_str("<")?;
 396                         } else {
 397                             f.write_str("&lt;")?;
 398                         }
 399                         let mut comma = false;
 400                         for arg in args {
 401                             if comma {
 402                                 f.write_str(", ")?;
 403                             }
 404                             comma = true;
 405                             if f.alternate() {
 406                                 write!(f, "{:#}", arg.print(cx))?;
 407                             } else {
 408                                 write!(f, "{}", arg.print(cx))?;
 409                             }
 410                         }
 411                         for binding in bindings {
 412                             if comma {
 413                                 f.write_str(", ")?;
 414                             }
 415                             comma = true;
 416                             if f.alternate() {
 417                                 write!(f, "{:#}", binding.print(cx))?;
 418                             } else {
 419                                 write!(f, "{}", binding.print(cx))?;
 420                             }
 421                         }
 422                         if f.alternate() {
 423                             f.write_str(">")?;
 424                         } else {
 425                             f.write_str("&gt;")?;
 426                         }
 427                     }
 428                 }
 429                 clean::GenericArgs::Parenthesized { inputs, output } => {
 430                     f.write_str("(")?;
 431                     let mut comma = false;
 432                     for ty in inputs {
 433                         if comma {
 434                             f.write_str(", ")?;
 435                         }
 436                         comma = true;
 437                         if f.alternate() {
 438                             write!(f, "{:#}", ty.print(cx))?;
 439                         } else {
 440                             write!(f, "{}", ty.print(cx))?;
 441                         }
 442                     }
 443                     f.write_str(")")?;
 444                     if let Some(ref ty) = *output {
 445                         if f.alternate() {
 446                             write!(f, " -> {:#}", ty.print(cx))?;
 447                         } else {
 448                             write!(f, " -&gt; {}", ty.print(cx))?;
 449                         }
 450                     }
 451                 }
 452             }
 453             Ok(())
 454         })
 455     }
 456 }
 457
 458 crate fn href(did: DefId, cx: &Context<'_>) -> Option<(String, ItemType, Vec<String>)> {
 459     let cache = &cx.cache();
 460     let relative_to = &cx.current;
 461     fn to_module_fqp(shortty: ItemType, fqp: &[String]) -> &[String] {
 462         if shortty == ItemType::Module { &fqp[..] } else { &fqp[..fqp.len() - 1] }
 463     }
 464
 465     if !did.is_local() && !cache.access_levels.is_public(did) && !cache.document_private {
 466         return None;
 467     }
 468
 469     let (fqp, shortty, mut url_parts) = match cache.paths.get(&did) {
 470         Some(&(ref fqp, shortty)) => (fqp, shortty, {
 471             let module_fqp = to_module_fqp(shortty, fqp);
 472             href_relative_parts(module_fqp, relative_to)
 473         }),
 474         None => {
 475             let &(ref fqp, shortty) = cache.external_paths.get(&did)?;
 476             let module_fqp = to_module_fqp(shortty, fqp);
 477             (
 478                 fqp,
 479                 shortty,
 480                 match cache.extern_locations[&did.krate] {
 481                     ExternalLocation::Remote(ref s) => {
 482                         let s = s.trim_end_matches('/');
 483                         let mut s = vec![&s[..]];
 484                         s.extend(module_fqp[..].iter().map(String::as_str));
 485                         s
 486                     }
 487                     ExternalLocation::Local => href_relative_parts(module_fqp, relative_to),
 488                     ExternalLocation::Unknown => return None,
 489                 },
 490             )
 491         }
 492     };
 493     let last = &fqp.last().unwrap()[..];
 494     let filename;
 495     match shortty {
 496         ItemType::Module => {
 497             url_parts.push("index.html");
 498         }
 499         _ => {
 500             filename = format!("{}.{}.html", shortty.as_str(), last);
 501             url_parts.push(&filename);
 502         }
 503     }
 504     Some((url_parts.join("/"), shortty, fqp.to_vec()))
 505 }
 506
 507 /// Both paths should only be modules.
 508 /// This is because modules get their own directories; that is, `std::vec` and `std::vec::Vec` will
 509 /// both need `../iter/trait.Iterator.html` to get at the iterator trait.
 510 crate fn href_relative_parts<'a>(fqp: &'a [String], relative_to_fqp: &'a [String]) -> Vec<&'a str> {
 511     for (i, (f, r)) in fqp.iter().zip(relative_to_fqp.iter()).enumerate() {
 512         // e.g. linking to std::iter from std::vec (`dissimilar_part_count` will be 1)
 513         if f != r {
 514             let dissimilar_part_count = relative_to_fqp.len() - i;
 515             let fqp_module = fqp[i..fqp.len()].iter().map(String::as_str);
 516             return iter::repeat("..").take(dissimilar_part_count).chain(fqp_module).collect();
 517         }
 518     }
 519     // e.g. linking to std::sync::atomic from std::sync
 520     if relative_to_fqp.len() < fqp.len() {
 521         fqp[relative_to_fqp.len()..fqp.len()].iter().map(String::as_str).collect()
 522     // e.g. linking to std::sync from std::sync::atomic
 523     } else if fqp.len() < relative_to_fqp.len() {
 524         let dissimilar_part_count = relative_to_fqp.len() - fqp.len();
 525         iter::repeat("..").take(dissimilar_part_count).collect()
 526     // linking to the same module
 527     } else {
 528         Vec::new()
 529     }
 530 }
 531
 532 /// Used when rendering a `ResolvedPath` structure. This invokes the `path`
 533 /// rendering function with the necessary arguments for linking to a local path.
 534 fn resolved_path<'a, 'cx: 'a>(
 535     w: &mut fmt::Formatter<'_>,
 536     did: DefId,
 537     path: &clean::Path,
 538     print_all: bool,
 539     use_absolute: bool,
 540     cx: &'cx Context<'_>,
 541 ) -> fmt::Result {
 542     let last = path.segments.last().unwrap();
 543
 544     if print_all {
 545         for seg in &path.segments[..path.segments.len() - 1] {
 546             write!(w, "{}::", seg.name)?;
 547         }
 548     }
 549     if w.alternate() {
 550         write!(w, "{}{:#}", &last.name, last.args.print(cx))?;
 551     } else {
 552         let path = if use_absolute {
 553             if let Some((_, _, fqp)) = href(did, cx) {
 554                 format!(
 555                     "{}::{}",
 556                     fqp[..fqp.len() - 1].join("::"),
 557                     anchor(did, fqp.last().unwrap(), cx)
 558                 )
 559             } else {
 560                 last.name.to_string()
 561             }
 562         } else {
 563             anchor(did, &*last.name.as_str(), cx).to_string()
 564         };
 565         write!(w, "{}{}", path, last.args.print(cx))?;
 566     }
 567     Ok(())
 568 }
 569
 570 fn primitive_link(
 571     f: &mut fmt::Formatter<'_>,
 572     prim: clean::PrimitiveType,
 573     name: &str,
 574     cx: &Context<'_>,
 575 ) -> fmt::Result {
 576     let m = &cx.cache();
 577     let mut needs_termination = false;
 578     if !f.alternate() {
 579         match m.primitive_locations.get(&prim) {
 580             Some(&def_id) if def_id.is_local() => {
 581                 let len = cx.current.len();
 582                 let len = if len == 0 { 0 } else { len - 1 };
 583                 write!(
 584                     f,
 585                     "<a class=\"primitive\" href=\"{}primitive.{}.html\">",
 586                     "../".repeat(len),
 587                     prim.as_sym()
 588                 )?;
 589                 needs_termination = true;
 590             }
 591             Some(&def_id) => {
 592                 let cname_str;
 593                 let loc = match m.extern_locations[&def_id.krate] {
 594                     ExternalLocation::Remote(ref s) => {
 595                         cname_str =
 596                             ExternalCrate { crate_num: def_id.krate }.name(cx.tcx()).as_str();
 597                         Some(vec![s.trim_end_matches('/'), &cname_str[..]])
 598                     }
 599                     ExternalLocation::Local => {
 600                         cname_str =
 601                             ExternalCrate { crate_num: def_id.krate }.name(cx.tcx()).as_str();
 602                         Some(if cx.current.first().map(|x| &x[..]) == Some(&cname_str[..]) {
 603                             iter::repeat("..").take(cx.current.len() - 1).collect()
 604                         } else {
 605                             let cname = iter::once(&cname_str[..]);
 606                             iter::repeat("..").take(cx.current.len()).chain(cname).collect()
 607                         })
 608                     }
 609                     ExternalLocation::Unknown => None,
 610                 };
 611                 if let Some(loc) = loc {
 612                     write!(
 613                         f,
 614                         "<a class=\"primitive\" href=\"{}/primitive.{}.html\">",
 615                         loc.join("/"),
 616                         prim.as_sym()
 617                     )?;
 618                     needs_termination = true;
 619                 }
 620             }
 621             None => {}
 622         }
 623     }
 624     write!(f, "{}", name)?;
 625     if needs_termination {
 626         write!(f, "</a>")?;
 627     }
 628     Ok(())
 629 }
 630
 631 /// Helper to render type parameters
 632 fn tybounds<'a, 'tcx: 'a>(
 633     param_names: &'a Option<Vec<clean::GenericBound>>,
 634     cx: &'a Context<'tcx>,
 635 ) -> impl fmt::Display + 'a + Captures<'tcx> {
 636     display_fn(move |f| match *param_names {
 637         Some(ref params) => {
 638             for param in params {
 639                 write!(f, " + ")?;
 640                 fmt::Display::fmt(&param.print(cx), f)?;
 641             }
 642             Ok(())
 643         }
 644         None => Ok(()),
 645     })
 646 }
 647
 648 crate fn anchor<'a, 'cx: 'a>(
 649     did: DefId,
 650     text: &'a str,
 651     cx: &'cx Context<'_>,
 652 ) -> impl fmt::Display + 'a {
 653     let parts = href(did.into(), cx);
 654     display_fn(move |f| {
 655         if let Some((url, short_ty, fqp)) = parts {
 656             write!(
 657                 f,
 658                 r#"<a class="{}" href="{}" title="{} {}">{}</a>"#,
 659                 short_ty,
 660                 url,
 661                 short_ty,
 662                 fqp.join("::"),
 663                 text
 664             )
 665         } else {
 666             write!(f, "{}", text)
 667         }
 668     })
 669 }
 670
 671 fn fmt_type<'cx>(
 672     t: &clean::Type,
 673     f: &mut fmt::Formatter<'_>,
 674     use_absolute: bool,
 675     cx: &'cx Context<'_>,
 676 ) -> fmt::Result {
 677     debug!("fmt_type(t = {:?})", t);
 678
 679     match *t {
 680         clean::Generic(name) => write!(f, "{}", name),
 681         clean::ResolvedPath { did, ref param_names, ref path, is_generic } => {
 682             if param_names.is_some() {
 683                 f.write_str("dyn ")?;
 684             }
 685             // Paths like `T::Output` and `Self::Output` should be rendered with all segments.
 686             resolved_path(f, did, path, is_generic, use_absolute, cx)?;
 687             fmt::Display::fmt(&tybounds(param_names, cx), f)
 688         }
 689         clean::Infer => write!(f, "_"),
 690         clean::Primitive(prim) => primitive_link(f, prim, &*prim.as_sym().as_str(), cx),
 691         clean::BareFunction(ref decl) => {
 692             if f.alternate() {
 693                 write!(
 694                     f,
 695                     "{:#}{}{:#}fn{:#}",
 696                     decl.print_hrtb_with_space(cx),
 697                     decl.unsafety.print_with_space(),
 698                     print_abi_with_space(decl.abi),
 699                     decl.decl.print(cx),
 700                 )
 701             } else {
 702                 write!(
 703                     f,
 704                     "{}{}{}",
 705                     decl.print_hrtb_with_space(cx),
 706                     decl.unsafety.print_with_space(),
 707                     print_abi_with_space(decl.abi)
 708                 )?;
 709                 primitive_link(f, PrimitiveType::Fn, "fn", cx)?;
 710                 write!(f, "{}", decl.decl.print(cx))
 711             }
 712         }
 713         clean::Tuple(ref typs) => {
 714             match &typs[..] {
 715                 &[] => primitive_link(f, PrimitiveType::Unit, "()", cx),
 716                 &[ref one] => {
 717                     primitive_link(f, PrimitiveType::Tuple, "(", cx)?;
 718                     // Carry `f.alternate()` into this display w/o branching manually.
 719                     fmt::Display::fmt(&one.print(cx), f)?;
 720                     primitive_link(f, PrimitiveType::Tuple, ",)", cx)
 721                 }
 722                 many => {
 723                     primitive_link(f, PrimitiveType::Tuple, "(", cx)?;
 724                     for (i, item) in many.iter().enumerate() {
 725                         if i != 0 {
 726                             write!(f, ", ")?;
 727                         }
 728                         fmt::Display::fmt(&item.print(cx), f)?;
 729                     }
 730                     primitive_link(f, PrimitiveType::Tuple, ")", cx)
 731                 }
 732             }
 733         }
 734         clean::Slice(ref t) => {
 735             primitive_link(f, PrimitiveType::Slice, "[", cx)?;
 736             fmt::Display::fmt(&t.print(cx), f)?;
 737             primitive_link(f, PrimitiveType::Slice, "]", cx)
 738         }
 739         clean::Array(ref t, ref n) => {
 740             primitive_link(f, PrimitiveType::Array, "[", cx)?;
 741             fmt::Display::fmt(&t.print(cx), f)?;
 742             if f.alternate() {
 743                 primitive_link(f, PrimitiveType::Array, &format!("; {}]", n), cx)
 744             } else {
 745                 primitive_link(f, PrimitiveType::Array, &format!("; {}]", Escape(n)), cx)
 746             }
 747         }
 748         clean::Never => primitive_link(f, PrimitiveType::Never, "!", cx),
 749         clean::RawPointer(m, ref t) => {
 750             let m = match m {
 751                 hir::Mutability::Mut => "mut",
 752                 hir::Mutability::Not => "const",
 753             };
 754             match **t {
 755                 clean::Generic(_) | clean::ResolvedPath { is_generic: true, .. } => {
 756                     if f.alternate() {
 757                         primitive_link(
 758                             f,
 759                             clean::PrimitiveType::RawPointer,
 760                             &format!("*{} {:#}", m, t.print(cx)),
 761                             cx,
 762                         )
 763                     } else {
 764                         primitive_link(
 765                             f,
 766                             clean::PrimitiveType::RawPointer,
 767                             &format!("*{} {}", m, t.print(cx)),
 768                             cx,
 769                         )
 770                     }
 771                 }
 772                 _ => {
 773                     primitive_link(f, clean::PrimitiveType::RawPointer, &format!("*{} ", m), cx)?;
 774                     fmt::Display::fmt(&t.print(cx), f)
 775                 }
 776             }
 777         }
 778         clean::BorrowedRef { lifetime: ref l, mutability, type_: ref ty } => {
 779             let lt = match l {
 780                 Some(l) => format!("{} ", l.print()),
 781                 _ => String::new(),
 782             };
 783             let m = mutability.print_with_space();
 784             let amp = if f.alternate() { "&".to_string() } else { "&amp;".to_string() };
 785             match **ty {
 786                 clean::Slice(ref bt) => {
 787                     // `BorrowedRef{ ... Slice(T) }` is `&[T]`
 788                     match **bt {
 789                         clean::Generic(_) => {
 790                             if f.alternate() {
 791                                 primitive_link(
 792                                     f,
 793                                     PrimitiveType::Slice,
 794                                     &format!("{}{}{}[{:#}]", amp, lt, m, bt.print(cx)),
 795                                     cx,
 796                                 )
 797                             } else {
 798                                 primitive_link(
 799                                     f,
 800                                     PrimitiveType::Slice,
 801                                     &format!("{}{}{}[{}]", amp, lt, m, bt.print(cx)),
 802                                     cx,
 803                                 )
 804                             }
 805                         }
 806                         _ => {
 807                             primitive_link(
 808                                 f,
 809                                 PrimitiveType::Slice,
 810                                 &format!("{}{}{}[", amp, lt, m),
 811                                 cx,
 812                             )?;
 813                             if f.alternate() {
 814                                 write!(f, "{:#}", bt.print(cx))?;
 815                             } else {
 816                                 write!(f, "{}", bt.print(cx))?;
 817                             }
 818                             primitive_link(f, PrimitiveType::Slice, "]", cx)
 819                         }
 820                     }
 821                 }
 822                 clean::ResolvedPath { param_names: Some(ref v), .. } if !v.is_empty() => {
 823                     write!(f, "{}{}{}(", amp, lt, m)?;
 824                     fmt_type(&ty, f, use_absolute, cx)?;
 825                     write!(f, ")")
 826                 }
 827                 clean::Generic(..) => {
 828                     primitive_link(
 829                         f,
 830                         PrimitiveType::Reference,
 831                         &format!("{}{}{}", amp, lt, m),
 832                         cx,
 833                     )?;
 834                     fmt_type(&ty, f, use_absolute, cx)
 835                 }
 836                 _ => {
 837                     write!(f, "{}{}{}", amp, lt, m)?;
 838                     fmt_type(&ty, f, use_absolute, cx)
 839                 }
 840             }
 841         }
 842         clean::ImplTrait(ref bounds) => {
 843             if f.alternate() {
 844                 write!(f, "impl {:#}", print_generic_bounds(bounds, cx))
 845             } else {
 846                 write!(f, "impl {}", print_generic_bounds(bounds, cx))
 847             }
 848         }
 849         clean::QPath { ref name, ref self_type, ref trait_, ref self_def_id } => {
 850             let should_show_cast = match *trait_ {
 851                 box clean::ResolvedPath { ref path, .. } => {
 852                     !path.segments.is_empty()
 853                         && self_def_id
 854                             .zip(trait_.def_id())
 855                             .map_or(!self_type.is_self_type(), |(id, trait_)| id != trait_)
 856                 }
 857                 _ => true,
 858             };
 859             if f.alternate() {
 860                 if should_show_cast {
 861                     write!(f, "<{:#} as {:#}>::", self_type.print(cx), trait_.print(cx))?
 862                 } else {
 863                     write!(f, "{:#}::", self_type.print(cx))?
 864                 }
 865             } else {
 866                 if should_show_cast {
 867                     write!(f, "&lt;{} as {}&gt;::", self_type.print(cx), trait_.print(cx))?
 868                 } else {
 869                     write!(f, "{}::", self_type.print(cx))?
 870                 }
 871             };
 872             match *trait_ {
 873                 // It's pretty unsightly to look at `<A as B>::C` in output, and
 874                 // we've got hyperlinking on our side, so try to avoid longer
 875                 // notation as much as possible by making `C` a hyperlink to trait
 876                 // `B` to disambiguate.
 877                 //
 878                 // FIXME: this is still a lossy conversion and there should probably
 879                 //        be a better way of representing this in general? Most of
 880                 //        the ugliness comes from inlining across crates where
 881                 //        everything comes in as a fully resolved QPath (hard to
 882                 //        look at).
 883                 box clean::ResolvedPath { did, ref param_names, .. } => {
 884                     match href(did.into(), cx) {
 885                         Some((ref url, _, ref path)) if !f.alternate() => {
 886                             write!(
 887                                 f,
 888                                 "<a class=\"type\" href=\"{url}#{shortty}.{name}\" \
 889                                     title=\"type {path}::{name}\">{name}</a>",
 890                                 url = url,
 891                                 shortty = ItemType::AssocType,
 892                                 name = name,
 893                                 path = path.join("::")
 894                             )?;
 895                         }
 896                         _ => write!(f, "{}", name)?,
 897                     }
 898
 899                     // FIXME: `param_names` are not rendered, and this seems bad?
 900                     drop(param_names);
 901                     Ok(())
 902                 }
 903                 _ => write!(f, "{}", name),
 904             }
 905         }
 906     }
 907 }
 908
 909 impl clean::Type {
 910     crate fn print<'b, 'a: 'b, 'tcx: 'a>(
 911         &'a self,
 912         cx: &'a Context<'tcx>,
 913     ) -> impl fmt::Display + 'b + Captures<'tcx> {
 914         display_fn(move |f| fmt_type(self, f, false, cx))
 915     }
 916 }
 917
 918 impl clean::Impl {
 919     crate fn print<'a, 'tcx: 'a>(
 920         &'a self,
 921         use_absolute: bool,
 922         cx: &'a Context<'tcx>,
 923     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 924         display_fn(move |f| {
 925             if f.alternate() {
 926                 write!(f, "impl{:#} ", self.generics.print(cx))?;
 927             } else {
 928                 write!(f, "impl{} ", self.generics.print(cx))?;
 929             }
 930
 931             if let Some(ref ty) = self.trait_ {
 932                 if self.negative_polarity {
 933                     write!(f, "!")?;
 934                 }
 935                 fmt::Display::fmt(&ty.print(cx), f)?;
 936                 write!(f, " for ")?;
 937             }
 938
 939             if let Some(ref ty) = self.blanket_impl {
 940                 fmt_type(ty, f, use_absolute, cx)?;
 941             } else {
 942                 fmt_type(&self.for_, f, use_absolute, cx)?;
 943             }
 944
 945             fmt::Display::fmt(&print_where_clause(&self.generics, cx, 0, true), f)?;
 946             Ok(())
 947         })
 948     }
 949 }
 950
 951 impl clean::Arguments {
 952     crate fn print<'a, 'tcx: 'a>(
 953         &'a self,
 954         cx: &'a Context<'tcx>,
 955     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 956         display_fn(move |f| {
 957             for (i, input) in self.values.iter().enumerate() {
 958                 if !input.name.is_empty() {
 959                     write!(f, "{}: ", input.name)?;
 960                 }
 961                 if f.alternate() {
 962                     write!(f, "{:#}", input.type_.print(cx))?;
 963                 } else {
 964                     write!(f, "{}", input.type_.print(cx))?;
 965                 }
 966                 if i + 1 < self.values.len() {
 967                     write!(f, ", ")?;
 968                 }
 969             }
 970             Ok(())
 971         })
 972     }
 973 }
 974
 975 impl clean::FnRetTy {
 976     crate fn print<'a, 'tcx: 'a>(
 977         &'a self,
 978         cx: &'a Context<'tcx>,
 979     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 980         display_fn(move |f| match self {
 981             clean::Return(clean::Tuple(tys)) if tys.is_empty() => Ok(()),
 982             clean::Return(ty) if f.alternate() => {
 983                 write!(f, " -> {:#}", ty.print(cx))
 984             }
 985             clean::Return(ty) => write!(f, " -&gt; {}", ty.print(cx)),
 986             clean::DefaultReturn => Ok(()),
 987         })
 988     }
 989 }
 990
 991 impl clean::BareFunctionDecl {
 992     fn print_hrtb_with_space<'a, 'tcx: 'a>(
 993         &'a self,
 994         cx: &'a Context<'tcx>,
 995     ) -> impl fmt::Display + 'a + Captures<'tcx> {
 996         display_fn(move |f| {
 997             if !self.generic_params.is_empty() {
 998                 write!(f, "for<{}> ", comma_sep(self.generic_params.iter().map(|g| g.print(cx))))
 999             } else {
1000                 Ok(())
1001             }
1002         })
1003     }
1004 }
1005
1006 impl clean::FnDecl {
1007     crate fn print<'b, 'a: 'b, 'tcx: 'a>(
1008         &'a self,
1009         cx: &'a Context<'tcx>,
1010     ) -> impl fmt::Display + 'b + Captures<'tcx> {
1011         display_fn(move |f| {
1012             let ellipsis = if self.c_variadic { ", ..." } else { "" };
1013             if f.alternate() {
1014                 write!(
1015                     f,
1016                     "({args:#}{ellipsis}){arrow:#}",
1017                     args = self.inputs.print(cx),
1018                     ellipsis = ellipsis,
1019                     arrow = self.output.print(cx)
1020                 )
1021             } else {
1022                 write!(
1023                     f,
1024                     "({args}{ellipsis}){arrow}",
1025                     args = self.inputs.print(cx),
1026                     ellipsis = ellipsis,
1027                     arrow = self.output.print(cx)
1028                 )
1029             }
1030         })
1031     }
1032
1033     /// * `header_len`: The length of the function header and name. In other words, the number of
1034     ///   characters in the function declaration up to but not including the parentheses.
1035     ///   <br>Used to determine line-wrapping.
1036     /// * `indent`: The number of spaces to indent each successive line with, if line-wrapping is
1037     ///   necessary.
1038     /// * `asyncness`: Whether the function is async or not.
1039     crate fn full_print<'a, 'tcx: 'a>(
1040         &'a self,
1041         header_len: usize,
1042         indent: usize,
1043         asyncness: hir::IsAsync,
1044         cx: &'a Context<'tcx>,
1045     ) -> impl fmt::Display + 'a + Captures<'tcx> {
1046         display_fn(move |f| self.inner_full_print(header_len, indent, asyncness, f, cx))
1047     }
1048
1049     fn inner_full_print(
1050         &self,
1051         header_len: usize,
1052         indent: usize,
1053         asyncness: hir::IsAsync,
1054         f: &mut fmt::Formatter<'_>,
1055         cx: &Context<'_>,
1056     ) -> fmt::Result {
1057         let amp = if f.alternate() { "&" } else { "&amp;" };
1058         let mut args = String::new();
1059         let mut args_plain = String::new();
1060         for (i, input) in self.inputs.values.iter().enumerate() {
1061             if i == 0 {
1062                 args.push_str("<br>");
1063             }
1064
1065             if let Some(selfty) = input.to_self() {
1066                 match selfty {
1067                     clean::SelfValue => {
1068                         args.push_str("self");
1069                         args_plain.push_str("self");
1070                     }
1071                     clean::SelfBorrowed(Some(ref lt), mtbl) => {
1072                         args.push_str(&format!(
1073                             "{}{} {}self",
1074                             amp,
1075                             lt.print(),
1076                             mtbl.print_with_space()
1077                         ));
1078                         args_plain.push_str(&format!(
1079                             "&{} {}self",
1080                             lt.print(),
1081                             mtbl.print_with_space()
1082                         ));
1083                     }
1084                     clean::SelfBorrowed(None, mtbl) => {
1085                         args.push_str(&format!("{}{}self", amp, mtbl.print_with_space()));
1086                         args_plain.push_str(&format!("&{}self", mtbl.print_with_space()));
1087                     }
1088                     clean::SelfExplicit(ref typ) => {
1089                         if f.alternate() {
1090                             args.push_str(&format!("self: {:#}", typ.print(cx)));
1091                         } else {
1092                             args.push_str(&format!("self: {}", typ.print(cx)));
1093                         }
1094                         args_plain.push_str(&format!("self: {:#}", typ.print(cx)));
1095                     }
1096                 }
1097             } else {
1098                 if i > 0 {
1099                     args.push_str(" <br>");
1100                     args_plain.push(' ');
1101                 }
1102                 if !input.name.is_empty() {
1103                     args.push_str(&format!("{}: ", input.name));
1104                     args_plain.push_str(&format!("{}: ", input.name));
1105                 }
1106
1107                 if f.alternate() {
1108                     args.push_str(&format!("{:#}", input.type_.print(cx)));
1109                 } else {
1110                     args.push_str(&input.type_.print(cx).to_string());
1111                 }
1112                 args_plain.push_str(&format!("{:#}", input.type_.print(cx)));
1113             }
1114             if i + 1 < self.inputs.values.len() {
1115                 args.push(',');
1116                 args_plain.push(',');
1117             }
1118         }
1119
1120         let mut args_plain = format!("({})", args_plain);
1121
1122         if self.c_variadic {
1123             args.push_str(",<br> ...");
1124             args_plain.push_str(", ...");
1125         }
1126
1127         let arrow_plain;
1128         let arrow = if let hir::IsAsync::Async = asyncness {
1129             let output = self.sugared_async_return_type();
1130             arrow_plain = format!("{:#}", output.print(cx));
1131             if f.alternate() { arrow_plain.clone() } else { format!("{}", output.print(cx)) }
1132         } else {
1133             arrow_plain = format!("{:#}", self.output.print(cx));
1134             if f.alternate() { arrow_plain.clone() } else { format!("{}", self.output.print(cx)) }
1135         };
1136
1137         let declaration_len = header_len + args_plain.len() + arrow_plain.len();
1138         let output = if declaration_len > 80 {
1139             let full_pad = format!("<br>{}", "&nbsp;".repeat(indent + 4));
1140             let close_pad = format!("<br>{}", "&nbsp;".repeat(indent));
1141             format!(
1142                 "({args}{close}){arrow}",
1143                 args = args.replace("<br>", &full_pad),
1144                 close = close_pad,
1145                 arrow = arrow
1146             )
1147         } else {
1148             format!("({args}){arrow}", args = args.replace("<br>", ""), arrow = arrow)
1149         };
1150
1151         if f.alternate() {
1152             write!(f, "{}", output.replace("<br>", "\n"))
1153         } else {
1154             write!(f, "{}", output)
1155         }
1156     }
1157 }
1158
1159 impl clean::Visibility {
1160     crate fn print_with_space<'a, 'tcx: 'a>(
1161         self,
1162         item_did: FakeDefId,
1163         cx: &'a Context<'tcx>,
1164     ) -> impl fmt::Display + 'a + Captures<'tcx> {
1165         let to_print = match self {
1166             clean::Public => "pub ".to_owned(),
1167             clean::Inherited => String::new(),
1168             clean::Visibility::Restricted(vis_did) => {
1169                 // FIXME(camelid): This may not work correctly if `item_did` is a module.
1170                 //                 However, rustdoc currently never displays a module's
1171                 //                 visibility, so it shouldn't matter.
1172                 let parent_module = find_nearest_parent_module(cx.tcx(), item_did.expect_real());
1173
1174                 if vis_did.index == CRATE_DEF_INDEX {
1175                     "pub(crate) ".to_owned()
1176                 } else if parent_module == Some(vis_did) {
1177                     // `pub(in foo)` where `foo` is the parent module
1178                     // is the same as no visibility modifier
1179                     String::new()
1180                 } else if parent_module
1181                     .map(|parent| find_nearest_parent_module(cx.tcx(), parent))
1182                     .flatten()
1183                     == Some(vis_did)
1184                 {
1185                     "pub(super) ".to_owned()
1186                 } else {
1187                     let path = cx.tcx().def_path(vis_did);
1188                     debug!("path={:?}", path);
1189                     // modified from `resolved_path()` to work with `DefPathData`
1190                     let last_name = path.data.last().unwrap().data.get_opt_name().unwrap();
1191                     let anchor = anchor(vis_did, &last_name.as_str(), cx).to_string();
1192
1193                     let mut s = "pub(in ".to_owned();
1194                     for seg in &path.data[..path.data.len() - 1] {
1195                         s.push_str(&format!("{}::", seg.data.get_opt_name().unwrap()));
1196                     }
1197                     s.push_str(&format!("{}) ", anchor));
1198                     s
1199                 }
1200             }
1201         };
1202         display_fn(move |f| f.write_str(&to_print))
1203     }
1204
1205     /// This function is the same as print_with_space, except that it renders no links.
1206     /// It's used for macros' rendered source view, which is syntax highlighted and cannot have
1207     /// any HTML in it.
1208     crate fn to_src_with_space<'a, 'tcx: 'a>(
1209         self,
1210         tcx: TyCtxt<'tcx>,
1211         item_did: DefId,
1212     ) -> impl fmt::Display + 'a + Captures<'tcx> {
1213         let to_print = match self {
1214             clean::Public => "pub ".to_owned(),
1215             clean::Inherited => String::new(),
1216             clean::Visibility::Restricted(vis_did) => {
1217                 // FIXME(camelid): This may not work correctly if `item_did` is a module.
1218                 //                 However, rustdoc currently never displays a module's
1219                 //                 visibility, so it shouldn't matter.
1220                 let parent_module = find_nearest_parent_module(tcx, item_did);
1221
1222                 if vis_did.index == CRATE_DEF_INDEX {
1223                     "pub(crate) ".to_owned()
1224                 } else if parent_module == Some(vis_did) {
1225                     // `pub(in foo)` where `foo` is the parent module
1226                     // is the same as no visibility modifier
1227                     String::new()
1228                 } else if parent_module
1229                     .map(|parent| find_nearest_parent_module(tcx, parent))
1230                     .flatten()
1231                     == Some(vis_did)
1232                 {
1233                     "pub(super) ".to_owned()
1234                 } else {
1235                     format!("pub(in {}) ", tcx.def_path_str(vis_did))
1236                 }
1237             }
1238         };
1239         display_fn(move |f| f.write_str(&to_print))
1240     }
1241 }
1242
1243 crate trait PrintWithSpace {
1244     fn print_with_space(&self) -> &str;
1245 }
1246
1247 impl PrintWithSpace for hir::Unsafety {
1248     fn print_with_space(&self) -> &str {
1249         match self {
1250             hir::Unsafety::Unsafe => "unsafe ",
1251             hir::Unsafety::Normal => "",
1252         }
1253     }
1254 }
1255
1256 impl PrintWithSpace for hir::Constness {
1257     fn print_with_space(&self) -> &str {
1258         match self {
1259             hir::Constness::Const => "const ",
1260             hir::Constness::NotConst => "",
1261         }
1262     }
1263 }
1264
1265 impl PrintWithSpace for hir::IsAsync {
1266     fn print_with_space(&self) -> &str {
1267         match self {
1268             hir::IsAsync::Async => "async ",
1269             hir::IsAsync::NotAsync => "",
1270         }
1271     }
1272 }
1273
1274 impl PrintWithSpace for hir::Mutability {
1275     fn print_with_space(&self) -> &str {
1276         match self {
1277             hir::Mutability::Not => "",
1278             hir::Mutability::Mut => "mut ",
1279         }
1280     }
1281 }
1282
1283 impl clean::Import {
1284     crate fn print<'a, 'tcx: 'a>(
1285         &'a self,
1286         cx: &'a Context<'tcx>,
1287     ) -> impl fmt::Display + 'a + Captures<'tcx> {
1288         display_fn(move |f| match self.kind {
1289             clean::ImportKind::Simple(name) => {
1290                 if name == self.source.path.last() {
1291                     write!(f, "use {};", self.source.print(cx))
1292                 } else {
1293                     write!(f, "use {} as {};", self.source.print(cx), name)
1294                 }
1295             }
1296             clean::ImportKind::Glob => {
1297                 if self.source.path.segments.is_empty() {
1298                     write!(f, "use *;")
1299                 } else {
1300                     write!(f, "use {}::*;", self.source.print(cx))
1301                 }
1302             }
1303         })
1304     }
1305 }
1306
1307 impl clean::ImportSource {
1308     crate fn print<'a, 'tcx: 'a>(
1309         &'a self,
1310         cx: &'a Context<'tcx>,
1311     ) -> impl fmt::Display + 'a + Captures<'tcx> {
1312         display_fn(move |f| match self.did {
1313             Some(did) => resolved_path(f, did, &self.path, true, false, cx),
1314             _ => {
1315                 for seg in &self.path.segments[..self.path.segments.len() - 1] {
1316                     write!(f, "{}::", seg.name)?;
1317                 }
1318                 let name = self.path.last_name();
1319                 if let hir::def::Res::PrimTy(p) = self.path.res {
1320                     primitive_link(f, PrimitiveType::from(p), &*name, cx)?;
1321                 } else {
1322                     write!(f, "{}", name)?;
1323                 }
1324                 Ok(())
1325             }
1326         })
1327     }
1328 }
1329
1330 impl clean::TypeBinding {
1331     crate fn print<'a, 'tcx: 'a>(
1332         &'a self,
1333         cx: &'a Context<'tcx>,
1334     ) -> impl fmt::Display + 'a + Captures<'tcx> {
1335         display_fn(move |f| {
1336             f.write_str(&*self.name.as_str())?;
1337             match self.kind {
1338                 clean::TypeBindingKind::Equality { ref ty } => {
1339                     if f.alternate() {
1340                         write!(f, " = {:#}", ty.print(cx))?;
1341                     } else {
1342                         write!(f, " = {}", ty.print(cx))?;
1343                     }
1344                 }
1345                 clean::TypeBindingKind::Constraint { ref bounds } => {
1346                     if !bounds.is_empty() {
1347                         if f.alternate() {
1348                             write!(f, ": {:#}", print_generic_bounds(bounds, cx))?;
1349                         } else {
1350                             write!(f, ":&nbsp;{}", print_generic_bounds(bounds, cx))?;
1351                         }
1352                     }
1353                 }
1354             }
1355             Ok(())
1356         })
1357     }
1358 }
1359
1360 crate fn print_abi_with_space(abi: Abi) -> impl fmt::Display {
1361     display_fn(move |f| {
1362         let quot = if f.alternate() { "\"" } else { "&quot;" };
1363         match abi {
1364             Abi::Rust => Ok(()),
1365             abi => write!(f, "extern {0}{1}{0} ", quot, abi.name()),
1366         }
1367     })
1368 }
1369
1370 crate fn print_default_space<'a>(v: bool) -> &'a str {
1371     if v { "default " } else { "" }
1372 }
1373
1374 impl clean::GenericArg {
1375     crate fn print<'a, 'tcx: 'a>(
1376         &'a self,
1377         cx: &'a Context<'tcx>,
1378     ) -> impl fmt::Display + 'a + Captures<'tcx> {
1379         display_fn(move |f| match self {
1380             clean::GenericArg::Lifetime(lt) => fmt::Display::fmt(&lt.print(), f),
1381             clean::GenericArg::Type(ty) => fmt::Display::fmt(&ty.print(cx), f),
1382             clean::GenericArg::Const(ct) => fmt::Display::fmt(&ct.print(cx.tcx()), f),
1383         })
1384     }
1385 }
1386
1387 crate fn display_fn(f: impl FnOnce(&mut fmt::Formatter<'_>) -> fmt::Result) -> impl fmt::Display {
1388     struct WithFormatter<F>(Cell<Option<F>>);
1389
1390     impl<F> fmt::Display for WithFormatter<F>
1391     where
1392         F: FnOnce(&mut fmt::Formatter<'_>) -> fmt::Result,
1393     {
1394         fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1395             (self.0.take()).unwrap()(f)
1396         }
1397     }
1398
1399     WithFormatter(Cell::new(Some(f)))
1400 }