src/librustdoc/html/render/mod.rs

   1 //! Rustdoc's HTML rendering module.
   2 //!
   3 //! This modules contains the bulk of the logic necessary for rendering a
   4 //! rustdoc `clean::Crate` instance to a set of static HTML pages. This
   5 //! rendering process is largely driven by the `format!` syntax extension to
   6 //! perform all I/O into files and streams.
   7 //!
   8 //! The rendering process is largely driven by the `Context` and `Cache`
   9 //! structures. The cache is pre-populated by crawling the crate in question,
  10 //! and then it is shared among the various rendering threads. The cache is meant
  11 //! to be a fairly large structure not implementing `Clone` (because it's shared
  12 //! among threads). The context, however, should be a lightweight structure. This
  13 //! is cloned per-thread and contains information about what is currently being
  14 //! rendered.
  15 //!
  16 //! In order to speed up rendering (mostly because of markdown rendering), the
  17 //! rendering process has been parallelized. This parallelization is only
  18 //! exposed through the `crate` method on the context, and then also from the
  19 //! fact that the shared cache is stored in TLS (and must be accessed as such).
  20 //!
  21 //! In addition to rendering the crate itself, this module is also responsible
  22 //! for creating the corresponding search index and source file renderings.
  23 //! These threads are not parallelized (they haven't been a bottleneck yet), and
  24 //! both occur before the crate is rendered.
  25
  26 crate mod cache;
  27
  28 #[cfg(test)]
  29 mod tests;
  30
  31 mod context;
  32 mod print_item;
  33 mod span_map;
  34 mod templates;
  35 mod write_shared;
  36
  37 crate use self::context::*;
  38 crate use self::span_map::{collect_spans_and_sources, LinkFromSrc};
  39
  40 use std::collections::VecDeque;
  41 use std::default::Default;
  42 use std::fmt;
  43 use std::fs;
  44 use std::iter::Peekable;
  45 use std::path::PathBuf;
  46 use std::str;
  47 use std::string::ToString;
  48
  49 use rustc_ast_pretty::pprust;
  50 use rustc_attr::{ConstStability, Deprecation, StabilityLevel};
  51 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  52 use rustc_hir as hir;
  53 use rustc_hir::def::CtorKind;
  54 use rustc_hir::def_id::DefId;
  55 use rustc_hir::Mutability;
  56 use rustc_middle::middle::stability;
  57 use rustc_middle::ty;
  58 use rustc_middle::ty::TyCtxt;
  59 use rustc_span::{
  60     symbol::{kw, sym, Symbol},
  61     BytePos, FileName, RealFileName,
  62 };
  63 use serde::ser::SerializeSeq;
  64 use serde::{Serialize, Serializer};
  65
  66 use crate::clean::{self, ItemId, RenderedLink, SelfTy};
  67 use crate::docfs::PathError;
  68 use crate::error::Error;
  69 use crate::formats::cache::Cache;
  70 use crate::formats::item_type::ItemType;
  71 use crate::formats::{AssocItemRender, Impl, RenderMode};
  72 use crate::html::escape::Escape;
  73 use crate::html::format::{
  74     href, print_abi_with_space, print_constness_with_space, print_default_space,
  75     print_generic_bounds, print_where_clause, Buffer, HrefError, PrintWithSpace,
  76 };
  77 use crate::html::highlight;
  78 use crate::html::markdown::{HeadingOffset, Markdown, MarkdownHtml, MarkdownSummaryLine};
  79 use crate::html::sources;
  80 use crate::scrape_examples::{CallData, CallLocation};
  81 use crate::try_none;
  82
  83 /// A pair of name and its optional document.
  84 crate type NameDoc = (String, Option<String>);
  85
  86 crate fn ensure_trailing_slash(v: &str) -> impl fmt::Display + '_ {
  87     crate::html::format::display_fn(move |f| {
  88         if !v.ends_with('/') && !v.is_empty() { write!(f, "{}/", v) } else { f.write_str(v) }
  89     })
  90 }
  91
  92 // Helper structs for rendering items/sidebars and carrying along contextual
  93 // information
  94
  95 /// Struct representing one entry in the JS search index. These are all emitted
  96 /// by hand to a large JS file at the end of cache-creation.
  97 #[derive(Debug)]
  98 crate struct IndexItem {
  99     crate ty: ItemType,
 100     crate name: String,
 101     crate path: String,
 102     crate desc: String,
 103     crate parent: Option<DefId>,
 104     crate parent_idx: Option<usize>,
 105     crate search_type: Option<IndexItemFunctionType>,
 106     crate aliases: Box<[String]>,
 107 }
 108
 109 /// A type used for the search index.
 110 #[derive(Debug)]
 111 crate struct RenderType {
 112     name: Option<String>,
 113     generics: Option<Vec<TypeWithKind>>,
 114 }
 115
 116 /// Full type of functions/methods in the search index.
 117 #[derive(Debug)]
 118 crate struct IndexItemFunctionType {
 119     inputs: Vec<TypeWithKind>,
 120     output: Vec<TypeWithKind>,
 121 }
 122
 123 impl Serialize for IndexItemFunctionType {
 124     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
 125     where
 126         S: Serializer,
 127     {
 128         // If we couldn't figure out a type, just write `null`.
 129         let has_missing = self.inputs.iter().chain(self.output.iter()).any(|i| i.ty.name.is_none());
 130         if has_missing {
 131             serializer.serialize_none()
 132         } else {
 133             let mut seq = serializer.serialize_seq(None)?;
 134             seq.serialize_element(&self.inputs)?;
 135             match self.output.as_slice() {
 136                 [] => {}
 137                 [one] => seq.serialize_element(one)?,
 138                 all => seq.serialize_element(all)?,
 139             }
 140             seq.end()
 141         }
 142     }
 143 }
 144
 145 #[derive(Debug)]
 146 crate struct TypeWithKind {
 147     ty: RenderType,
 148     kind: ItemType,
 149 }
 150
 151 impl From<(RenderType, ItemType)> for TypeWithKind {
 152     fn from(x: (RenderType, ItemType)) -> TypeWithKind {
 153         TypeWithKind { ty: x.0, kind: x.1 }
 154     }
 155 }
 156
 157 impl Serialize for TypeWithKind {
 158     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
 159     where
 160         S: Serializer,
 161     {
 162         let mut seq = serializer.serialize_seq(None)?;
 163         seq.serialize_element(&self.ty.name)?;
 164         seq.serialize_element(&self.kind)?;
 165         if let Some(generics) = &self.ty.generics {
 166             seq.serialize_element(generics)?;
 167         }
 168         seq.end()
 169     }
 170 }
 171
 172 #[derive(Debug, Clone)]
 173 crate struct StylePath {
 174     /// The path to the theme
 175     crate path: PathBuf,
 176     /// What the `disabled` attribute should be set to in the HTML tag
 177     crate disabled: bool,
 178 }
 179
 180 fn write_srclink(cx: &Context<'_>, item: &clean::Item, buf: &mut Buffer) {
 181     if let Some(l) = cx.src_href(item) {
 182         write!(buf, "<a class=\"srclink\" href=\"{}\" title=\"goto source code\">[src]</a>", l)
 183     }
 184 }
 185
 186 #[derive(Debug, Eq, PartialEq, Hash)]
 187 struct ItemEntry {
 188     url: String,
 189     name: String,
 190 }
 191
 192 impl ItemEntry {
 193     fn new(mut url: String, name: String) -> ItemEntry {
 194         while url.starts_with('/') {
 195             url.remove(0);
 196         }
 197         ItemEntry { url, name }
 198     }
 199 }
 200
 201 impl ItemEntry {
 202     crate fn print(&self) -> impl fmt::Display + '_ {
 203         crate::html::format::display_fn(move |f| {
 204             write!(f, "<a href=\"{}\">{}</a>", self.url, Escape(&self.name))
 205         })
 206     }
 207 }
 208
 209 impl PartialOrd for ItemEntry {
 210     fn partial_cmp(&self, other: &ItemEntry) -> Option<::std::cmp::Ordering> {
 211         Some(self.cmp(other))
 212     }
 213 }
 214
 215 impl Ord for ItemEntry {
 216     fn cmp(&self, other: &ItemEntry) -> ::std::cmp::Ordering {
 217         self.name.cmp(&other.name)
 218     }
 219 }
 220
 221 #[derive(Debug)]
 222 struct AllTypes {
 223     structs: FxHashSet<ItemEntry>,
 224     enums: FxHashSet<ItemEntry>,
 225     unions: FxHashSet<ItemEntry>,
 226     primitives: FxHashSet<ItemEntry>,
 227     traits: FxHashSet<ItemEntry>,
 228     macros: FxHashSet<ItemEntry>,
 229     functions: FxHashSet<ItemEntry>,
 230     typedefs: FxHashSet<ItemEntry>,
 231     opaque_tys: FxHashSet<ItemEntry>,
 232     statics: FxHashSet<ItemEntry>,
 233     constants: FxHashSet<ItemEntry>,
 234     attributes: FxHashSet<ItemEntry>,
 235     derives: FxHashSet<ItemEntry>,
 236     trait_aliases: FxHashSet<ItemEntry>,
 237 }
 238
 239 impl AllTypes {
 240     fn new() -> AllTypes {
 241         let new_set = |cap| FxHashSet::with_capacity_and_hasher(cap, Default::default());
 242         AllTypes {
 243             structs: new_set(100),
 244             enums: new_set(100),
 245             unions: new_set(100),
 246             primitives: new_set(26),
 247             traits: new_set(100),
 248             macros: new_set(100),
 249             functions: new_set(100),
 250             typedefs: new_set(100),
 251             opaque_tys: new_set(100),
 252             statics: new_set(100),
 253             constants: new_set(100),
 254             attributes: new_set(100),
 255             derives: new_set(100),
 256             trait_aliases: new_set(100),
 257         }
 258     }
 259
 260     fn append(&mut self, item_name: String, item_type: &ItemType) {
 261         let mut url: Vec<_> = item_name.split("::").skip(1).collect();
 262         if let Some(name) = url.pop() {
 263             let new_url = format!("{}/{}.{}.html", url.join("/"), item_type, name);
 264             url.push(name);
 265             let name = url.join("::");
 266             match *item_type {
 267                 ItemType::Struct => self.structs.insert(ItemEntry::new(new_url, name)),
 268                 ItemType::Enum => self.enums.insert(ItemEntry::new(new_url, name)),
 269                 ItemType::Union => self.unions.insert(ItemEntry::new(new_url, name)),
 270                 ItemType::Primitive => self.primitives.insert(ItemEntry::new(new_url, name)),
 271                 ItemType::Trait => self.traits.insert(ItemEntry::new(new_url, name)),
 272                 ItemType::Macro => self.macros.insert(ItemEntry::new(new_url, name)),
 273                 ItemType::Function => self.functions.insert(ItemEntry::new(new_url, name)),
 274                 ItemType::Typedef => self.typedefs.insert(ItemEntry::new(new_url, name)),
 275                 ItemType::OpaqueTy => self.opaque_tys.insert(ItemEntry::new(new_url, name)),
 276                 ItemType::Static => self.statics.insert(ItemEntry::new(new_url, name)),
 277                 ItemType::Constant => self.constants.insert(ItemEntry::new(new_url, name)),
 278                 ItemType::ProcAttribute => self.attributes.insert(ItemEntry::new(new_url, name)),
 279                 ItemType::ProcDerive => self.derives.insert(ItemEntry::new(new_url, name)),
 280                 ItemType::TraitAlias => self.trait_aliases.insert(ItemEntry::new(new_url, name)),
 281                 _ => true,
 282             };
 283         }
 284     }
 285 }
 286
 287 impl AllTypes {
 288     fn print(self, f: &mut Buffer) {
 289         fn print_entries(f: &mut Buffer, e: &FxHashSet<ItemEntry>, title: &str, class: &str) {
 290             if !e.is_empty() {
 291                 let mut e: Vec<&ItemEntry> = e.iter().collect();
 292                 e.sort();
 293                 write!(
 294                     f,
 295                     "<h3 id=\"{}\">{}</h3><ul class=\"{} docblock\">",
 296                     title.replace(' ', "-"), // IDs cannot contain whitespaces.
 297                     title,
 298                     class
 299                 );
 300
 301                 for s in e.iter() {
 302                     write!(f, "<li>{}</li>", s.print());
 303                 }
 304
 305                 f.write_str("</ul>");
 306             }
 307         }
 308
 309         f.write_str(
 310             "<h1 class=\"fqn\">\
 311                  <span class=\"in-band\">List of all items</span>\
 312                  <span class=\"out-of-band\">\
 313                      <span id=\"render-detail\">\
 314                          <a id=\"toggle-all-docs\" href=\"javascript:void(0)\" \
 315                             title=\"collapse all docs\">\
 316                              [<span class=\"inner\">&#x2212;</span>]\
 317                          </a>\
 318                      </span>
 319                  </span>
 320              </h1>",
 321         );
 322         // Note: print_entries does not escape the title, because we know the current set of titles
 323         // doesn't require escaping.
 324         print_entries(f, &self.structs, "Structs", "structs");
 325         print_entries(f, &self.enums, "Enums", "enums");
 326         print_entries(f, &self.unions, "Unions", "unions");
 327         print_entries(f, &self.primitives, "Primitives", "primitives");
 328         print_entries(f, &self.traits, "Traits", "traits");
 329         print_entries(f, &self.macros, "Macros", "macros");
 330         print_entries(f, &self.attributes, "Attribute Macros", "attributes");
 331         print_entries(f, &self.derives, "Derive Macros", "derives");
 332         print_entries(f, &self.functions, "Functions", "functions");
 333         print_entries(f, &self.typedefs, "Typedefs", "typedefs");
 334         print_entries(f, &self.trait_aliases, "Trait Aliases", "trait-aliases");
 335         print_entries(f, &self.opaque_tys, "Opaque Types", "opaque-types");
 336         print_entries(f, &self.statics, "Statics", "statics");
 337         print_entries(f, &self.constants, "Constants", "constants")
 338     }
 339 }
 340
 341 #[derive(Debug)]
 342 enum Setting {
 343     Section {
 344         description: &'static str,
 345         sub_settings: Vec<Setting>,
 346     },
 347     Toggle {
 348         js_data_name: &'static str,
 349         description: &'static str,
 350         default_value: bool,
 351     },
 352     Select {
 353         js_data_name: &'static str,
 354         description: &'static str,
 355         default_value: &'static str,
 356         options: Vec<(String, String)>,
 357     },
 358 }
 359
 360 impl Setting {
 361     fn display(&self, root_path: &str, suffix: &str) -> String {
 362         match *self {
 363             Setting::Section { description, ref sub_settings } => format!(
 364                 "<div class=\"setting-line\">\
 365                      <div class=\"title\">{}</div>\
 366                      <div class=\"sub-settings\">{}</div>
 367                  </div>",
 368                 description,
 369                 sub_settings.iter().map(|s| s.display(root_path, suffix)).collect::<String>()
 370             ),
 371             Setting::Toggle { js_data_name, description, default_value } => format!(
 372                 "<div class=\"setting-line\">\
 373                      <label class=\"toggle\">\
 374                      <input type=\"checkbox\" id=\"{}\" {}>\
 375                      <span class=\"slider\"></span>\
 376                      </label>\
 377                      <div>{}</div>\
 378                  </div>",
 379                 js_data_name,
 380                 if default_value { " checked" } else { "" },
 381                 description,
 382             ),
 383             Setting::Select { js_data_name, description, default_value, ref options } => format!(
 384                 "<div class=\"setting-line\">\
 385                      <div>{}</div>\
 386                      <label class=\"select-wrapper\">\
 387                          <select id=\"{}\" autocomplete=\"off\">{}</select>\
 388                          <img src=\"{}down-arrow{}.svg\" alt=\"Select item\">\
 389                      </label>\
 390                  </div>",
 391                 description,
 392                 js_data_name,
 393                 options
 394                     .iter()
 395                     .map(|opt| format!(
 396                         "<option value=\"{}\" {}>{}</option>",
 397                         opt.0,
 398                         if opt.0 == default_value { "selected" } else { "" },
 399                         opt.1,
 400                     ))
 401                     .collect::<String>(),
 402                 root_path,
 403                 suffix,
 404             ),
 405         }
 406     }
 407 }
 408
 409 impl From<(&'static str, &'static str, bool)> for Setting {
 410     fn from(values: (&'static str, &'static str, bool)) -> Setting {
 411         Setting::Toggle { js_data_name: values.0, description: values.1, default_value: values.2 }
 412     }
 413 }
 414
 415 impl<T: Into<Setting>> From<(&'static str, Vec<T>)> for Setting {
 416     fn from(values: (&'static str, Vec<T>)) -> Setting {
 417         Setting::Section {
 418             description: values.0,
 419             sub_settings: values.1.into_iter().map(|v| v.into()).collect::<Vec<_>>(),
 420         }
 421     }
 422 }
 423
 424 fn settings(root_path: &str, suffix: &str, themes: &[StylePath]) -> Result<String, Error> {
 425     let theme_names: Vec<(String, String)> = themes
 426         .iter()
 427         .map(|entry| {
 428             let theme =
 429                 try_none!(try_none!(entry.path.file_stem(), &entry.path).to_str(), &entry.path)
 430                     .to_string();
 431
 432             Ok((theme.clone(), theme))
 433         })
 434         .collect::<Result<_, Error>>()?;
 435
 436     // (id, explanation, default value)
 437     let settings: &[Setting] = &[
 438         (
 439             "Theme preferences",
 440             vec![
 441                 Setting::from(("use-system-theme", "Use system theme", true)),
 442                 Setting::Select {
 443                     js_data_name: "preferred-dark-theme",
 444                     description: "Preferred dark theme",
 445                     default_value: "dark",
 446                     options: theme_names.clone(),
 447                 },
 448                 Setting::Select {
 449                     js_data_name: "preferred-light-theme",
 450                     description: "Preferred light theme",
 451                     default_value: "light",
 452                     options: theme_names,
 453                 },
 454             ],
 455         )
 456             .into(),
 457         ("auto-hide-large-items", "Auto-hide item contents for large items.", true).into(),
 458         ("auto-hide-method-docs", "Auto-hide item methods' documentation", false).into(),
 459         ("auto-hide-trait-implementations", "Auto-hide trait implementation documentation", false)
 460             .into(),
 461         ("go-to-only-result", "Directly go to item in search if there is only one result", false)
 462             .into(),
 463         ("line-numbers", "Show line numbers on code examples", false).into(),
 464         ("disable-shortcuts", "Disable keyboard shortcuts", false).into(),
 465     ];
 466
 467     Ok(format!(
 468         "<h1 class=\"fqn\">\
 469             <span class=\"in-band\">Rustdoc settings</span>\
 470         </h1>\
 471         <div class=\"settings\">{}</div>\
 472         <script src=\"{}settings{}.js\"></script>",
 473         settings.iter().map(|s| s.display(root_path, suffix)).collect::<String>(),
 474         root_path,
 475         suffix
 476     ))
 477 }
 478
 479 fn document(
 480     w: &mut Buffer,
 481     cx: &Context<'_>,
 482     item: &clean::Item,
 483     parent: Option<&clean::Item>,
 484     heading_offset: HeadingOffset,
 485 ) {
 486     if let Some(ref name) = item.name {
 487         info!("Documenting {}", name);
 488     }
 489     document_item_info(w, cx, item, parent);
 490     if parent.is_none() {
 491         document_full_collapsible(w, item, cx, heading_offset);
 492     } else {
 493         document_full(w, item, cx, heading_offset);
 494     }
 495 }
 496
 497 /// Render md_text as markdown.
 498 fn render_markdown(
 499     w: &mut Buffer,
 500     cx: &Context<'_>,
 501     md_text: &str,
 502     links: Vec<RenderedLink>,
 503     heading_offset: HeadingOffset,
 504 ) {
 505     let mut ids = cx.id_map.borrow_mut();
 506     write!(
 507         w,
 508         "<div class=\"docblock\">{}</div>",
 509         Markdown {
 510             content: md_text,
 511             links: &links,
 512             ids: &mut ids,
 513             error_codes: cx.shared.codes,
 514             edition: cx.shared.edition(),
 515             playground: &cx.shared.playground,
 516             heading_offset,
 517         }
 518         .into_string()
 519     )
 520 }
 521
 522 /// Writes a documentation block containing only the first paragraph of the documentation. If the
 523 /// docs are longer, a "Read more" link is appended to the end.
 524 fn document_short(
 525     w: &mut Buffer,
 526     item: &clean::Item,
 527     cx: &Context<'_>,
 528     link: AssocItemLink<'_>,
 529     parent: &clean::Item,
 530     show_def_docs: bool,
 531 ) {
 532     document_item_info(w, cx, item, Some(parent));
 533     if !show_def_docs {
 534         return;
 535     }
 536     if let Some(s) = item.doc_value() {
 537         let mut summary_html = MarkdownSummaryLine(&s, &item.links(cx)).into_string();
 538
 539         if s.contains('\n') {
 540             let link = format!(r#" <a href="{}">Read more</a>"#, naive_assoc_href(item, link, cx));
 541
 542             if let Some(idx) = summary_html.rfind("</p>") {
 543                 summary_html.insert_str(idx, &link);
 544             } else {
 545                 summary_html.push_str(&link);
 546             }
 547         }
 548
 549         write!(w, "<div class='docblock'>{}</div>", summary_html,);
 550     }
 551 }
 552
 553 fn document_full_collapsible(
 554     w: &mut Buffer,
 555     item: &clean::Item,
 556     cx: &Context<'_>,
 557     heading_offset: HeadingOffset,
 558 ) {
 559     document_full_inner(w, item, cx, true, heading_offset);
 560 }
 561
 562 fn document_full(
 563     w: &mut Buffer,
 564     item: &clean::Item,
 565     cx: &Context<'_>,
 566     heading_offset: HeadingOffset,
 567 ) {
 568     document_full_inner(w, item, cx, false, heading_offset);
 569 }
 570
 571 fn document_full_inner(
 572     w: &mut Buffer,
 573     item: &clean::Item,
 574     cx: &Context<'_>,
 575     is_collapsible: bool,
 576     heading_offset: HeadingOffset,
 577 ) {
 578     if let Some(s) = cx.shared.maybe_collapsed_doc_value(item) {
 579         debug!("Doc block: =====\n{}\n=====", s);
 580         if is_collapsible {
 581             w.write_str(
 582                 "<details class=\"rustdoc-toggle top-doc\" open>\
 583                 <summary class=\"hideme\">\
 584                      <span>Expand description</span>\
 585                 </summary>",
 586             );
 587             render_markdown(w, cx, &s, item.links(cx), heading_offset);
 588             w.write_str("</details>");
 589         } else {
 590             render_markdown(w, cx, &s, item.links(cx), heading_offset);
 591         }
 592     }
 593
 594     let kind = match &*item.kind {
 595         clean::ItemKind::StrippedItem(box kind) | kind => kind,
 596     };
 597
 598     if let clean::ItemKind::FunctionItem(..) | clean::ItemKind::MethodItem(..) = kind {
 599         render_call_locations(w, cx, item);
 600     }
 601 }
 602
 603 /// Add extra information about an item such as:
 604 ///
 605 /// * Stability
 606 /// * Deprecated
 607 /// * Required features (through the `doc_cfg` feature)
 608 fn document_item_info(
 609     w: &mut Buffer,
 610     cx: &Context<'_>,
 611     item: &clean::Item,
 612     parent: Option<&clean::Item>,
 613 ) {
 614     let item_infos = short_item_info(item, cx, parent);
 615     if !item_infos.is_empty() {
 616         w.write_str("<div class=\"item-info\">");
 617         for info in item_infos {
 618             w.write_str(&info);
 619         }
 620         w.write_str("</div>");
 621     }
 622 }
 623
 624 fn portability(item: &clean::Item, parent: Option<&clean::Item>) -> Option<String> {
 625     let cfg = match (&item.cfg, parent.and_then(|p| p.cfg.as_ref())) {
 626         (Some(cfg), Some(parent_cfg)) => cfg.simplify_with(parent_cfg),
 627         (cfg, _) => cfg.as_deref().cloned(),
 628     };
 629
 630     debug!("Portability {:?} - {:?} = {:?}", item.cfg, parent.and_then(|p| p.cfg.as_ref()), cfg);
 631
 632     Some(format!("<div class=\"stab portability\">{}</div>", cfg?.render_long_html()))
 633 }
 634
 635 /// Render the stability, deprecation and portability information that is displayed at the top of
 636 /// the item's documentation.
 637 fn short_item_info(
 638     item: &clean::Item,
 639     cx: &Context<'_>,
 640     parent: Option<&clean::Item>,
 641 ) -> Vec<String> {
 642     let mut extra_info = vec![];
 643     let error_codes = cx.shared.codes;
 644
 645     if let Some(depr @ Deprecation { note, since, is_since_rustc_version: _, suggestion: _ }) =
 646         item.deprecation(cx.tcx())
 647     {
 648         // We display deprecation messages for #[deprecated] and #[rustc_deprecated]
 649         // but only display the future-deprecation messages for #[rustc_deprecated].
 650         let mut message = if let Some(since) = since {
 651             let since = &since.as_str();
 652             if !stability::deprecation_in_effect(&depr) {
 653                 if *since == "TBD" {
 654                     String::from("Deprecating in a future Rust version")
 655                 } else {
 656                     format!("Deprecating in {}", Escape(since))
 657                 }
 658             } else {
 659                 format!("Deprecated since {}", Escape(since))
 660             }
 661         } else {
 662             String::from("Deprecated")
 663         };
 664
 665         if let Some(note) = note {
 666             let note = note.as_str();
 667             let mut ids = cx.id_map.borrow_mut();
 668             let html = MarkdownHtml(
 669                 &note,
 670                 &mut ids,
 671                 error_codes,
 672                 cx.shared.edition(),
 673                 &cx.shared.playground,
 674             );
 675             message.push_str(&format!(": {}", html.into_string()));
 676         }
 677         extra_info.push(format!(
 678             "<div class=\"stab deprecated\"><span class=\"emoji\">👎</span> {}</div>",
 679             message,
 680         ));
 681     }
 682
 683     // Render unstable items. But don't render "rustc_private" crates (internal compiler crates).
 684     // Those crates are permanently unstable so it makes no sense to render "unstable" everywhere.
 685     if let Some((StabilityLevel::Unstable { reason, issue, .. }, feature)) = item
 686         .stability(cx.tcx())
 687         .as_ref()
 688         .filter(|stab| stab.feature != sym::rustc_private)
 689         .map(|stab| (stab.level, stab.feature))
 690     {
 691         let mut message =
 692             "<span class=\"emoji\">🔬</span> This is a nightly-only experimental API.".to_owned();
 693
 694         let mut feature = format!("<code>{}</code>", Escape(&feature.as_str()));
 695         if let (Some(url), Some(issue)) = (&cx.shared.issue_tracker_base_url, issue) {
 696             feature.push_str(&format!(
 697                 "&nbsp;<a href=\"{url}{issue}\">#{issue}</a>",
 698                 url = url,
 699                 issue = issue
 700             ));
 701         }
 702
 703         message.push_str(&format!(" ({})", feature));
 704
 705         if let Some(unstable_reason) = reason {
 706             let mut ids = cx.id_map.borrow_mut();
 707             message = format!(
 708                 "<details><summary>{}</summary>{}</details>",
 709                 message,
 710                 MarkdownHtml(
 711                     &unstable_reason.as_str(),
 712                     &mut ids,
 713                     error_codes,
 714                     cx.shared.edition(),
 715                     &cx.shared.playground,
 716                 )
 717                 .into_string()
 718             );
 719         }
 720
 721         extra_info.push(format!("<div class=\"stab unstable\">{}</div>", message));
 722     }
 723
 724     if let Some(portability) = portability(item, parent) {
 725         extra_info.push(portability);
 726     }
 727
 728     extra_info
 729 }
 730
 731 // Render the list of items inside one of the sections "Trait Implementations",
 732 // "Auto Trait Implementations," "Blanket Trait Implementations" (on struct/enum pages).
 733 fn render_impls(cx: &Context<'_>, w: &mut Buffer, impls: &[&&Impl], containing_item: &clean::Item) {
 734     let tcx = cx.tcx();
 735     let mut rendered_impls = impls
 736         .iter()
 737         .map(|i| {
 738             let did = i.trait_did().unwrap();
 739             let provided_trait_methods = i.inner_impl().provided_trait_methods(tcx);
 740             let assoc_link = AssocItemLink::GotoSource(did.into(), &provided_trait_methods);
 741             let mut buffer = if w.is_for_html() { Buffer::html() } else { Buffer::new() };
 742             render_impl(
 743                 &mut buffer,
 744                 cx,
 745                 i,
 746                 containing_item,
 747                 assoc_link,
 748                 RenderMode::Normal,
 749                 None,
 750                 &[],
 751                 ImplRenderingParameters {
 752                     show_def_docs: true,
 753                     is_on_foreign_type: false,
 754                     show_default_items: true,
 755                     show_non_assoc_items: true,
 756                     toggle_open_by_default: true,
 757                 },
 758             );
 759             buffer.into_inner()
 760         })
 761         .collect::<Vec<_>>();
 762     rendered_impls.sort();
 763     w.write_str(&rendered_impls.join(""));
 764 }
 765
 766 fn naive_assoc_href(it: &clean::Item, link: AssocItemLink<'_>, cx: &Context<'_>) -> String {
 767     use crate::formats::item_type::ItemType::*;
 768
 769     let name = it.name.as_ref().unwrap();
 770     let ty = match it.type_() {
 771         Typedef | AssocType => AssocType,
 772         s => s,
 773     };
 774
 775     let anchor = format!("#{}.{}", ty, name);
 776     match link {
 777         AssocItemLink::Anchor(Some(ref id)) => format!("#{}", id),
 778         AssocItemLink::Anchor(None) => anchor,
 779         AssocItemLink::GotoSource(did, _) => {
 780             href(did.expect_def_id(), cx).map(|p| format!("{}{}", p.0, anchor)).unwrap_or(anchor)
 781         }
 782     }
 783 }
 784
 785 fn assoc_const(
 786     w: &mut Buffer,
 787     it: &clean::Item,
 788     ty: &clean::Type,
 789     _default: Option<&String>,
 790     link: AssocItemLink<'_>,
 791     extra: &str,
 792     cx: &Context<'_>,
 793 ) {
 794     write!(
 795         w,
 796         "{}{}const <a href=\"{}\" class=\"constant\">{}</a>: {}",
 797         extra,
 798         it.visibility.print_with_space(it.def_id, cx),
 799         naive_assoc_href(it, link, cx),
 800         it.name.as_ref().unwrap(),
 801         ty.print(cx)
 802     );
 803 }
 804
 805 fn assoc_type(
 806     w: &mut Buffer,
 807     it: &clean::Item,
 808     bounds: &[clean::GenericBound],
 809     default: Option<&clean::Type>,
 810     link: AssocItemLink<'_>,
 811     extra: &str,
 812     cx: &Context<'_>,
 813 ) {
 814     write!(
 815         w,
 816         "{}type <a href=\"{}\" class=\"type\">{}</a>",
 817         extra,
 818         naive_assoc_href(it, link, cx),
 819         it.name.as_ref().unwrap()
 820     );
 821     if !bounds.is_empty() {
 822         write!(w, ": {}", print_generic_bounds(bounds, cx))
 823     }
 824     if let Some(default) = default {
 825         write!(w, " = {}", default.print(cx))
 826     }
 827 }
 828
 829 fn render_stability_since_raw(
 830     w: &mut Buffer,
 831     ver: Option<&str>,
 832     const_stability: Option<&ConstStability>,
 833     containing_ver: Option<&str>,
 834     containing_const_ver: Option<&str>,
 835 ) {
 836     let ver = ver.filter(|inner| !inner.is_empty());
 837
 838     match (ver, const_stability) {
 839         // stable and const stable
 840         (Some(v), Some(ConstStability { level: StabilityLevel::Stable { since }, .. }))
 841             if Some(since.as_str()).as_deref() != containing_const_ver =>
 842         {
 843             write!(
 844                 w,
 845                 "<span class=\"since\" title=\"Stable since Rust version {0}, const since {1}\">{0} (const: {1})</span>",
 846                 v, since
 847             );
 848         }
 849         // stable and const unstable
 850         (
 851             Some(v),
 852             Some(ConstStability { level: StabilityLevel::Unstable { issue, .. }, feature, .. }),
 853         ) => {
 854             write!(
 855                 w,
 856                 "<span class=\"since\" title=\"Stable since Rust version {0}, const unstable\">{0} (const: ",
 857                 v
 858             );
 859             if let Some(n) = issue {
 860                 write!(
 861                     w,
 862                     "<a href=\"https://github.com/rust-lang/rust/issues/{}\" title=\"Tracking issue for {}\">unstable</a>",
 863                     n, feature
 864                 );
 865             } else {
 866                 write!(w, "unstable");
 867             }
 868             write!(w, ")</span>");
 869         }
 870         // stable
 871         (Some(v), _) if ver != containing_ver => {
 872             write!(
 873                 w,
 874                 "<span class=\"since\" title=\"Stable since Rust version {0}\">{0}</span>",
 875                 v
 876             );
 877         }
 878         _ => {}
 879     }
 880 }
 881
 882 fn render_assoc_item(
 883     w: &mut Buffer,
 884     item: &clean::Item,
 885     link: AssocItemLink<'_>,
 886     parent: ItemType,
 887     cx: &Context<'_>,
 888 ) {
 889     fn method(
 890         w: &mut Buffer,
 891         meth: &clean::Item,
 892         header: hir::FnHeader,
 893         g: &clean::Generics,
 894         d: &clean::FnDecl,
 895         link: AssocItemLink<'_>,
 896         parent: ItemType,
 897         cx: &Context<'_>,
 898     ) {
 899         let name = meth.name.as_ref().unwrap();
 900         let href = match link {
 901             AssocItemLink::Anchor(Some(ref id)) => Some(format!("#{}", id)),
 902             AssocItemLink::Anchor(None) => Some(format!("#{}.{}", meth.type_(), name)),
 903             AssocItemLink::GotoSource(did, provided_methods) => {
 904                 // We're creating a link from an impl-item to the corresponding
 905                 // trait-item and need to map the anchored type accordingly.
 906                 let ty = if provided_methods.contains(name) {
 907                     ItemType::Method
 908                 } else {
 909                     ItemType::TyMethod
 910                 };
 911
 912                 match (href(did.expect_def_id(), cx), ty) {
 913                     (Ok(p), ty) => Some(format!("{}#{}.{}", p.0, ty, name)),
 914                     (Err(HrefError::DocumentationNotBuilt), ItemType::TyMethod) => None,
 915                     (Err(_), ty) => Some(format!("#{}.{}", ty, name)),
 916                 }
 917             }
 918         };
 919         let vis = meth.visibility.print_with_space(meth.def_id, cx).to_string();
 920         let constness =
 921             print_constness_with_space(&header.constness, meth.const_stability(cx.tcx()));
 922         let asyncness = header.asyncness.print_with_space();
 923         let unsafety = header.unsafety.print_with_space();
 924         let defaultness = print_default_space(meth.is_default());
 925         let abi = print_abi_with_space(header.abi).to_string();
 926
 927         // NOTE: `{:#}` does not print HTML formatting, `{}` does. So `g.print` can't be reused between the length calculation and `write!`.
 928         let generics_len = format!("{:#}", g.print(cx)).len();
 929         let mut header_len = "fn ".len()
 930             + vis.len()
 931             + constness.len()
 932             + asyncness.len()
 933             + unsafety.len()
 934             + defaultness.len()
 935             + abi.len()
 936             + name.as_str().len()
 937             + generics_len;
 938
 939         let (indent, indent_str, end_newline) = if parent == ItemType::Trait {
 940             header_len += 4;
 941             let indent_str = "    ";
 942             render_attributes_in_pre(w, meth, indent_str);
 943             (4, indent_str, false)
 944         } else {
 945             render_attributes_in_code(w, meth);
 946             (0, "", true)
 947         };
 948         w.reserve(header_len + "<a href=\"\" class=\"fnname\">{".len() + "</a>".len());
 949         write!(
 950             w,
 951             "{indent}{vis}{constness}{asyncness}{unsafety}{defaultness}{abi}fn <a {href} class=\"fnname\">{name}</a>\
 952              {generics}{decl}{notable_traits}{where_clause}",
 953             indent = indent_str,
 954             vis = vis,
 955             constness = constness,
 956             asyncness = asyncness,
 957             unsafety = unsafety,
 958             defaultness = defaultness,
 959             abi = abi,
 960             // links without a href are valid - https://www.w3schools.com/tags/att_a_href.asp
 961             href = href.map(|href| format!("href=\"{}\"", href)).unwrap_or_else(|| "".to_string()),
 962             name = name,
 963             generics = g.print(cx),
 964             decl = d.full_print(header_len, indent, header.asyncness, cx),
 965             notable_traits = notable_traits_decl(d, cx),
 966             where_clause = print_where_clause(g, cx, indent, end_newline),
 967         )
 968     }
 969     match *item.kind {
 970         clean::StrippedItem(..) => {}
 971         clean::TyMethodItem(ref m) => {
 972             method(w, item, m.header, &m.generics, &m.decl, link, parent, cx)
 973         }
 974         clean::MethodItem(ref m, _) => {
 975             method(w, item, m.header, &m.generics, &m.decl, link, parent, cx)
 976         }
 977         clean::AssocConstItem(ref ty, ref default) => assoc_const(
 978             w,
 979             item,
 980             ty,
 981             default.as_ref(),
 982             link,
 983             if parent == ItemType::Trait { "    " } else { "" },
 984             cx,
 985         ),
 986         clean::AssocTypeItem(ref bounds, ref default) => assoc_type(
 987             w,
 988             item,
 989             bounds,
 990             default.as_ref(),
 991             link,
 992             if parent == ItemType::Trait { "    " } else { "" },
 993             cx,
 994         ),
 995         _ => panic!("render_assoc_item called on non-associated-item"),
 996     }
 997 }
 998
 999 const ALLOWED_ATTRIBUTES: &[Symbol] =
1000     &[sym::export_name, sym::link_section, sym::no_mangle, sym::repr, sym::non_exhaustive];
1001
1002 fn attributes(it: &clean::Item) -> Vec<String> {
1003     it.attrs
1004         .other_attrs
1005         .iter()
1006         .filter_map(|attr| {
1007             if ALLOWED_ATTRIBUTES.contains(&attr.name_or_empty()) {
1008                 Some(pprust::attribute_to_string(attr).replace("\n", "").replace("  ", " "))
1009             } else {
1010                 None
1011             }
1012         })
1013         .collect()
1014 }
1015
1016 // When an attribute is rendered inside a `<pre>` tag, it is formatted using
1017 // a whitespace prefix and newline.
1018 fn render_attributes_in_pre(w: &mut Buffer, it: &clean::Item, prefix: &str) {
1019     for a in attributes(it) {
1020         writeln!(w, "{}{}", prefix, a);
1021     }
1022 }
1023
1024 // When an attribute is rendered inside a <code> tag, it is formatted using
1025 // a div to produce a newline after it.
1026 fn render_attributes_in_code(w: &mut Buffer, it: &clean::Item) {
1027     for a in attributes(it) {
1028         write!(w, "<div class=\"code-attribute\">{}</div>", a);
1029     }
1030 }
1031
1032 #[derive(Copy, Clone)]
1033 enum AssocItemLink<'a> {
1034     Anchor(Option<&'a str>),
1035     GotoSource(ItemId, &'a FxHashSet<Symbol>),
1036 }
1037
1038 impl<'a> AssocItemLink<'a> {
1039     fn anchor(&self, id: &'a str) -> Self {
1040         match *self {
1041             AssocItemLink::Anchor(_) => AssocItemLink::Anchor(Some(id)),
1042             ref other => *other,
1043         }
1044     }
1045 }
1046
1047 fn render_assoc_items(
1048     w: &mut Buffer,
1049     cx: &Context<'_>,
1050     containing_item: &clean::Item,
1051     it: DefId,
1052     what: AssocItemRender<'_>,
1053 ) {
1054     let mut derefs = FxHashSet::default();
1055     derefs.insert(it);
1056     render_assoc_items_inner(w, cx, containing_item, it, what, &mut derefs)
1057 }
1058
1059 fn render_assoc_items_inner(
1060     w: &mut Buffer,
1061     cx: &Context<'_>,
1062     containing_item: &clean::Item,
1063     it: DefId,
1064     what: AssocItemRender<'_>,
1065     derefs: &mut FxHashSet<DefId>,
1066 ) {
1067     info!("Documenting associated items of {:?}", containing_item.name);
1068     let cache = cx.cache();
1069     let v = match cache.impls.get(&it) {
1070         Some(v) => v,
1071         None => return,
1072     };
1073     let (non_trait, traits): (Vec<_>, _) = v.iter().partition(|i| i.inner_impl().trait_.is_none());
1074     if !non_trait.is_empty() {
1075         let mut tmp_buf = Buffer::empty_from(w);
1076         let render_mode = match what {
1077             AssocItemRender::All => {
1078                 tmp_buf.write_str(
1079                     "<h2 id=\"implementations\" class=\"small-section-header\">\
1080                          Implementations<a href=\"#implementations\" class=\"anchor\"></a>\
1081                     </h2>",
1082                 );
1083                 RenderMode::Normal
1084             }
1085             AssocItemRender::DerefFor { trait_, type_, deref_mut_ } => {
1086                 let id =
1087                     cx.derive_id(small_url_encode(format!("deref-methods-{:#}", type_.print(cx))));
1088                 if let Some(def_id) = type_.def_id(cx.cache()) {
1089                     cx.deref_id_map.borrow_mut().insert(def_id, id.clone());
1090                 }
1091                 write!(
1092                     tmp_buf,
1093                     "<h2 id=\"{id}\" class=\"small-section-header\">\
1094                          <span>Methods from {trait_}&lt;Target = {type_}&gt;</span>\
1095                          <a href=\"#{id}\" class=\"anchor\"></a>\
1096                      </h2>",
1097                     id = id,
1098                     trait_ = trait_.print(cx),
1099                     type_ = type_.print(cx),
1100                 );
1101                 RenderMode::ForDeref { mut_: deref_mut_ }
1102             }
1103         };
1104         let mut impls_buf = Buffer::empty_from(w);
1105         for i in &non_trait {
1106             render_impl(
1107                 &mut impls_buf,
1108                 cx,
1109                 i,
1110                 containing_item,
1111                 AssocItemLink::Anchor(None),
1112                 render_mode,
1113                 None,
1114                 &[],
1115                 ImplRenderingParameters {
1116                     show_def_docs: true,
1117                     is_on_foreign_type: false,
1118                     show_default_items: true,
1119                     show_non_assoc_items: true,
1120                     toggle_open_by_default: true,
1121                 },
1122             );
1123         }
1124         if !impls_buf.is_empty() {
1125             w.push_buffer(tmp_buf);
1126             w.push_buffer(impls_buf);
1127         }
1128     }
1129
1130     if !traits.is_empty() {
1131         let deref_impl =
1132             traits.iter().find(|t| t.trait_did() == cx.tcx().lang_items().deref_trait());
1133         if let Some(impl_) = deref_impl {
1134             let has_deref_mut =
1135                 traits.iter().any(|t| t.trait_did() == cx.tcx().lang_items().deref_mut_trait());
1136             render_deref_methods(w, cx, impl_, containing_item, has_deref_mut, derefs);
1137         }
1138
1139         // If we were already one level into rendering deref methods, we don't want to render
1140         // anything after recursing into any further deref methods above.
1141         if let AssocItemRender::DerefFor { .. } = what {
1142             return;
1143         }
1144
1145         let (synthetic, concrete): (Vec<&&Impl>, Vec<&&Impl>) =
1146             traits.iter().partition(|t| t.inner_impl().kind.is_auto());
1147         let (blanket_impl, concrete): (Vec<&&Impl>, _) =
1148             concrete.into_iter().partition(|t| t.inner_impl().kind.is_blanket());
1149
1150         let mut impls = Buffer::empty_from(w);
1151         render_impls(cx, &mut impls, &concrete, containing_item);
1152         let impls = impls.into_inner();
1153         if !impls.is_empty() {
1154             write!(
1155                 w,
1156                 "<h2 id=\"trait-implementations\" class=\"small-section-header\">\
1157                      Trait Implementations<a href=\"#trait-implementations\" class=\"anchor\"></a>\
1158                  </h2>\
1159                  <div id=\"trait-implementations-list\">{}</div>",
1160                 impls
1161             );
1162         }
1163
1164         if !synthetic.is_empty() {
1165             w.write_str(
1166                 "<h2 id=\"synthetic-implementations\" class=\"small-section-header\">\
1167                      Auto Trait Implementations\
1168                      <a href=\"#synthetic-implementations\" class=\"anchor\"></a>\
1169                  </h2>\
1170                  <div id=\"synthetic-implementations-list\">",
1171             );
1172             render_impls(cx, w, &synthetic, containing_item);
1173             w.write_str("</div>");
1174         }
1175
1176         if !blanket_impl.is_empty() {
1177             w.write_str(
1178                 "<h2 id=\"blanket-implementations\" class=\"small-section-header\">\
1179                      Blanket Implementations\
1180                      <a href=\"#blanket-implementations\" class=\"anchor\"></a>\
1181                  </h2>\
1182                  <div id=\"blanket-implementations-list\">",
1183             );
1184             render_impls(cx, w, &blanket_impl, containing_item);
1185             w.write_str("</div>");
1186         }
1187     }
1188 }
1189
1190 fn render_deref_methods(
1191     w: &mut Buffer,
1192     cx: &Context<'_>,
1193     impl_: &Impl,
1194     container_item: &clean::Item,
1195     deref_mut: bool,
1196     derefs: &mut FxHashSet<DefId>,
1197 ) {
1198     let cache = cx.cache();
1199     let deref_type = impl_.inner_impl().trait_.as_ref().unwrap();
1200     let (target, real_target) = impl_
1201         .inner_impl()
1202         .items
1203         .iter()
1204         .find_map(|item| match *item.kind {
1205             clean::TypedefItem(ref t, true) => Some(match *t {
1206                 clean::Typedef { item_type: Some(ref type_), .. } => (type_, &t.type_),
1207                 _ => (&t.type_, &t.type_),
1208             }),
1209             _ => None,
1210         })
1211         .expect("Expected associated type binding");
1212     debug!("Render deref methods for {:#?}, target {:#?}", impl_.inner_impl().for_, target);
1213     let what =
1214         AssocItemRender::DerefFor { trait_: deref_type, type_: real_target, deref_mut_: deref_mut };
1215     if let Some(did) = target.def_id(cache) {
1216         if let Some(type_did) = impl_.inner_impl().for_.def_id(cache) {
1217             // `impl Deref<Target = S> for S`
1218             if did == type_did || !derefs.insert(did) {
1219                 // Avoid infinite cycles
1220                 return;
1221             }
1222         }
1223         render_assoc_items_inner(w, cx, container_item, did, what, derefs);
1224     } else {
1225         if let Some(prim) = target.primitive_type() {
1226             if let Some(&did) = cache.primitive_locations.get(&prim) {
1227                 render_assoc_items_inner(w, cx, container_item, did, what, derefs);
1228             }
1229         }
1230     }
1231 }
1232
1233 fn should_render_item(item: &clean::Item, deref_mut_: bool, tcx: TyCtxt<'_>) -> bool {
1234     let self_type_opt = match *item.kind {
1235         clean::MethodItem(ref method, _) => method.decl.self_type(),
1236         clean::TyMethodItem(ref method) => method.decl.self_type(),
1237         _ => None,
1238     };
1239
1240     if let Some(self_ty) = self_type_opt {
1241         let (by_mut_ref, by_box, by_value) = match self_ty {
1242             SelfTy::SelfBorrowed(_, mutability)
1243             | SelfTy::SelfExplicit(clean::BorrowedRef { mutability, .. }) => {
1244                 (mutability == Mutability::Mut, false, false)
1245             }
1246             SelfTy::SelfExplicit(clean::ResolvedPath { did, .. }) => {
1247                 (false, Some(did) == tcx.lang_items().owned_box(), false)
1248             }
1249             SelfTy::SelfValue => (false, false, true),
1250             _ => (false, false, false),
1251         };
1252
1253         (deref_mut_ || !by_mut_ref) && !by_box && !by_value
1254     } else {
1255         false
1256     }
1257 }
1258
1259 fn notable_traits_decl(decl: &clean::FnDecl, cx: &Context<'_>) -> String {
1260     let mut out = Buffer::html();
1261
1262     if let Some(did) = decl.output.as_return().and_then(|t| t.def_id(cx.cache())) {
1263         if let Some(impls) = cx.cache().impls.get(&did) {
1264             for i in impls {
1265                 let impl_ = i.inner_impl();
1266                 if let Some(trait_) = &impl_.trait_ {
1267                     let trait_did = trait_.def_id();
1268
1269                     if cx.cache().traits.get(&trait_did).map_or(false, |t| t.is_notable) {
1270                         if out.is_empty() {
1271                             write!(
1272                                 &mut out,
1273                                 "<div class=\"notable\">Notable traits for {}</div>\
1274                              <code class=\"content\">",
1275                                 impl_.for_.print(cx)
1276                             );
1277                         }
1278
1279                         //use the "where" class here to make it small
1280                         write!(
1281                             &mut out,
1282                             "<span class=\"where fmt-newline\">{}</span>",
1283                             impl_.print(false, cx)
1284                         );
1285                         for it in &impl_.items {
1286                             if let clean::TypedefItem(ref tydef, _) = *it.kind {
1287                                 out.push_str("<span class=\"where fmt-newline\">    ");
1288                                 let empty_set = FxHashSet::default();
1289                                 let src_link =
1290                                     AssocItemLink::GotoSource(trait_did.into(), &empty_set);
1291                                 assoc_type(&mut out, it, &[], Some(&tydef.type_), src_link, "", cx);
1292                                 out.push_str(";</span>");
1293                             }
1294                         }
1295                     }
1296                 }
1297             }
1298         }
1299     }
1300
1301     if !out.is_empty() {
1302         out.insert_str(
1303             0,
1304             "<span class=\"notable-traits\"><span class=\"notable-traits-tooltip\">ⓘ\
1305             <div class=\"notable-traits-tooltiptext\"><span class=\"docblock\">",
1306         );
1307         out.push_str("</code></span></div></span></span>");
1308     }
1309
1310     out.into_inner()
1311 }
1312
1313 #[derive(Clone, Copy, Debug)]
1314 struct ImplRenderingParameters {
1315     show_def_docs: bool,
1316     is_on_foreign_type: bool,
1317     show_default_items: bool,
1318     /// Whether or not to show methods.
1319     show_non_assoc_items: bool,
1320     toggle_open_by_default: bool,
1321 }
1322
1323 fn render_impl(
1324     w: &mut Buffer,
1325     cx: &Context<'_>,
1326     i: &Impl,
1327     parent: &clean::Item,
1328     link: AssocItemLink<'_>,
1329     render_mode: RenderMode,
1330     use_absolute: Option<bool>,
1331     aliases: &[String],
1332     rendering_params: ImplRenderingParameters,
1333 ) {
1334     let cache = cx.cache();
1335     let traits = &cache.traits;
1336     let trait_ = i.trait_did().map(|did| &traits[&did]);
1337     let mut close_tags = String::new();
1338
1339     // For trait implementations, the `interesting` output contains all methods that have doc
1340     // comments, and the `boring` output contains all methods that do not. The distinction is
1341     // used to allow hiding the boring methods.
1342     // `containing_item` is used for rendering stability info. If the parent is a trait impl,
1343     // `containing_item` will the grandparent, since trait impls can't have stability attached.
1344     fn doc_impl_item(
1345         boring: &mut Buffer,
1346         interesting: &mut Buffer,
1347         cx: &Context<'_>,
1348         item: &clean::Item,
1349         parent: &clean::Item,
1350         containing_item: &clean::Item,
1351         link: AssocItemLink<'_>,
1352         render_mode: RenderMode,
1353         is_default_item: bool,
1354         trait_: Option<&clean::Trait>,
1355         rendering_params: ImplRenderingParameters,
1356     ) {
1357         let item_type = item.type_();
1358         let name = item.name.as_ref().unwrap();
1359
1360         let render_method_item = rendering_params.show_non_assoc_items
1361             && match render_mode {
1362                 RenderMode::Normal => true,
1363                 RenderMode::ForDeref { mut_: deref_mut_ } => {
1364                     should_render_item(item, deref_mut_, cx.tcx())
1365                 }
1366             };
1367
1368         let in_trait_class = if trait_.is_some() { " trait-impl" } else { "" };
1369
1370         let mut doc_buffer = Buffer::empty_from(boring);
1371         let mut info_buffer = Buffer::empty_from(boring);
1372         let mut short_documented = true;
1373
1374         if render_method_item {
1375             if !is_default_item {
1376                 if let Some(t) = trait_ {
1377                     // The trait item may have been stripped so we might not
1378                     // find any documentation or stability for it.
1379                     if let Some(it) = t.items.iter().find(|i| i.name == item.name) {
1380                         // We need the stability of the item from the trait
1381                         // because impls can't have a stability.
1382                         if item.doc_value().is_some() {
1383                             document_item_info(&mut info_buffer, cx, it, Some(parent));
1384                             document_full(&mut doc_buffer, item, cx, HeadingOffset::H5);
1385                             short_documented = false;
1386                         } else {
1387                             // In case the item isn't documented,
1388                             // provide short documentation from the trait.
1389                             document_short(
1390                                 &mut doc_buffer,
1391                                 it,
1392                                 cx,
1393                                 link,
1394                                 parent,
1395                                 rendering_params.show_def_docs,
1396                             );
1397                         }
1398                     }
1399                 } else {
1400                     document_item_info(&mut info_buffer, cx, item, Some(parent));
1401                     if rendering_params.show_def_docs {
1402                         document_full(&mut doc_buffer, item, cx, HeadingOffset::H5);
1403                         short_documented = false;
1404                     }
1405                 }
1406             } else {
1407                 document_short(
1408                     &mut doc_buffer,
1409                     item,
1410                     cx,
1411                     link,
1412                     parent,
1413                     rendering_params.show_def_docs,
1414                 );
1415             }
1416         }
1417         let w = if short_documented && trait_.is_some() { interesting } else { boring };
1418
1419         let toggled = !doc_buffer.is_empty();
1420         if toggled {
1421             let method_toggle_class =
1422                 if item_type == ItemType::Method { " method-toggle" } else { "" };
1423             write!(w, "<details class=\"rustdoc-toggle{}\" open><summary>", method_toggle_class);
1424         }
1425         match *item.kind {
1426             clean::MethodItem(..) | clean::TyMethodItem(_) => {
1427                 // Only render when the method is not static or we allow static methods
1428                 if render_method_item {
1429                     let id = cx.derive_id(format!("{}.{}", item_type, name));
1430                     let source_id = trait_
1431                         .and_then(|trait_| {
1432                             trait_.items.iter().find(|item| {
1433                                 item.name.map(|n| n.as_str().eq(&name.as_str())).unwrap_or(false)
1434                             })
1435                         })
1436                         .map(|item| format!("{}.{}", item.type_(), name));
1437                     write!(
1438                         w,
1439                         "<div id=\"{}\" class=\"{}{} has-srclink\">",
1440                         id, item_type, in_trait_class,
1441                     );
1442                     render_rightside(w, cx, item, containing_item);
1443                     write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
1444                     w.write_str("<h4 class=\"code-header\">");
1445                     render_assoc_item(
1446                         w,
1447                         item,
1448                         link.anchor(source_id.as_ref().unwrap_or(&id)),
1449                         ItemType::Impl,
1450                         cx,
1451                     );
1452                     w.write_str("</h4>");
1453                     w.write_str("</div>");
1454                 }
1455             }
1456             clean::TypedefItem(ref tydef, _) => {
1457                 let source_id = format!("{}.{}", ItemType::AssocType, name);
1458                 let id = cx.derive_id(source_id.clone());
1459                 write!(
1460                     w,
1461                     "<div id=\"{}\" class=\"{}{} has-srclink\">",
1462                     id, item_type, in_trait_class
1463                 );
1464                 write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
1465                 w.write_str("<h4 class=\"code-header\">");
1466                 assoc_type(
1467                     w,
1468                     item,
1469                     &Vec::new(),
1470                     Some(&tydef.type_),
1471                     link.anchor(if trait_.is_some() { &source_id } else { &id }),
1472                     "",
1473                     cx,
1474                 );
1475                 w.write_str("</h4>");
1476                 w.write_str("</div>");
1477             }
1478             clean::AssocConstItem(ref ty, ref default) => {
1479                 let source_id = format!("{}.{}", item_type, name);
1480                 let id = cx.derive_id(source_id.clone());
1481                 write!(
1482                     w,
1483                     "<div id=\"{}\" class=\"{}{} has-srclink\">",
1484                     id, item_type, in_trait_class
1485                 );
1486                 render_rightside(w, cx, item, containing_item);
1487                 write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
1488                 w.write_str("<h4 class=\"code-header\">");
1489                 assoc_const(
1490                     w,
1491                     item,
1492                     ty,
1493                     default.as_ref(),
1494                     link.anchor(if trait_.is_some() { &source_id } else { &id }),
1495                     "",
1496                     cx,
1497                 );
1498                 w.write_str("</h4>");
1499                 w.write_str("</div>");
1500             }
1501             clean::AssocTypeItem(ref bounds, ref default) => {
1502                 let source_id = format!("{}.{}", item_type, name);
1503                 let id = cx.derive_id(source_id.clone());
1504                 write!(w, "<div id=\"{}\" class=\"{}{}\">", id, item_type, in_trait_class,);
1505                 write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
1506                 w.write_str("<h4 class=\"code-header\">");
1507                 assoc_type(
1508                     w,
1509                     item,
1510                     bounds,
1511                     default.as_ref(),
1512                     link.anchor(if trait_.is_some() { &source_id } else { &id }),
1513                     "",
1514                     cx,
1515                 );
1516                 w.write_str("</h4>");
1517                 w.write_str("</div>");
1518             }
1519             clean::StrippedItem(..) => return,
1520             _ => panic!("can't make docs for trait item with name {:?}", item.name),
1521         }
1522
1523         w.push_buffer(info_buffer);
1524         if toggled {
1525             w.write_str("</summary>");
1526             w.push_buffer(doc_buffer);
1527             w.push_str("</details>");
1528         }
1529     }
1530
1531     let mut impl_items = Buffer::empty_from(w);
1532     let mut default_impl_items = Buffer::empty_from(w);
1533
1534     for trait_item in &i.inner_impl().items {
1535         doc_impl_item(
1536             &mut default_impl_items,
1537             &mut impl_items,
1538             cx,
1539             trait_item,
1540             if trait_.is_some() { &i.impl_item } else { parent },
1541             parent,
1542             link,
1543             render_mode,
1544             false,
1545             trait_.map(|t| &t.trait_),
1546             rendering_params,
1547         );
1548     }
1549
1550     fn render_default_items(
1551         boring: &mut Buffer,
1552         interesting: &mut Buffer,
1553         cx: &Context<'_>,
1554         t: &clean::Trait,
1555         i: &clean::Impl,
1556         parent: &clean::Item,
1557         containing_item: &clean::Item,
1558         render_mode: RenderMode,
1559         rendering_params: ImplRenderingParameters,
1560     ) {
1561         for trait_item in &t.items {
1562             let n = trait_item.name;
1563             if i.items.iter().any(|m| m.name == n) {
1564                 continue;
1565             }
1566             let did = i.trait_.as_ref().unwrap().def_id();
1567             let provided_methods = i.provided_trait_methods(cx.tcx());
1568             let assoc_link = AssocItemLink::GotoSource(did.into(), &provided_methods);
1569
1570             doc_impl_item(
1571                 boring,
1572                 interesting,
1573                 cx,
1574                 trait_item,
1575                 parent,
1576                 containing_item,
1577                 assoc_link,
1578                 render_mode,
1579                 true,
1580                 Some(t),
1581                 rendering_params,
1582             );
1583         }
1584     }
1585
1586     // If we've implemented a trait, then also emit documentation for all
1587     // default items which weren't overridden in the implementation block.
1588     // We don't emit documentation for default items if they appear in the
1589     // Implementations on Foreign Types or Implementors sections.
1590     if rendering_params.show_default_items {
1591         if let Some(t) = trait_ {
1592             render_default_items(
1593                 &mut default_impl_items,
1594                 &mut impl_items,
1595                 cx,
1596                 &t.trait_,
1597                 i.inner_impl(),
1598                 &i.impl_item,
1599                 parent,
1600                 render_mode,
1601                 rendering_params,
1602             );
1603         }
1604     }
1605     if render_mode == RenderMode::Normal {
1606         let toggled = !(impl_items.is_empty() && default_impl_items.is_empty());
1607         if toggled {
1608             close_tags.insert_str(0, "</details>");
1609             write!(
1610                 w,
1611                 "<details class=\"rustdoc-toggle implementors-toggle\"{}>",
1612                 if rendering_params.toggle_open_by_default { " open" } else { "" }
1613             );
1614             write!(w, "<summary>")
1615         }
1616         render_impl_summary(
1617             w,
1618             cx,
1619             i,
1620             parent,
1621             parent,
1622             rendering_params.show_def_docs,
1623             use_absolute,
1624             rendering_params.is_on_foreign_type,
1625             aliases,
1626         );
1627         if toggled {
1628             write!(w, "</summary>")
1629         }
1630
1631         if let Some(ref dox) = cx.shared.maybe_collapsed_doc_value(&i.impl_item) {
1632             let mut ids = cx.id_map.borrow_mut();
1633             write!(
1634                 w,
1635                 "<div class=\"docblock\">{}</div>",
1636                 Markdown {
1637                     content: &*dox,
1638                     links: &i.impl_item.links(cx),
1639                     ids: &mut ids,
1640                     error_codes: cx.shared.codes,
1641                     edition: cx.shared.edition(),
1642                     playground: &cx.shared.playground,
1643                     heading_offset: HeadingOffset::H4
1644                 }
1645                 .into_string()
1646             );
1647         }
1648     }
1649     if !default_impl_items.is_empty() || !impl_items.is_empty() {
1650         w.write_str("<div class=\"impl-items\">");
1651         w.push_buffer(default_impl_items);
1652         w.push_buffer(impl_items);
1653         close_tags.insert_str(0, "</div>");
1654     }
1655     w.write_str(&close_tags);
1656 }
1657
1658 // Render the items that appear on the right side of methods, impls, and
1659 // associated types. For example "1.0.0 (const: 1.39.0) [src]".
1660 fn render_rightside(
1661     w: &mut Buffer,
1662     cx: &Context<'_>,
1663     item: &clean::Item,
1664     containing_item: &clean::Item,
1665 ) {
1666     let tcx = cx.tcx();
1667
1668     write!(w, "<div class=\"rightside\">");
1669     render_stability_since_raw(
1670         w,
1671         item.stable_since(tcx).as_deref(),
1672         item.const_stability(tcx),
1673         containing_item.stable_since(tcx).as_deref(),
1674         containing_item.const_stable_since(tcx).as_deref(),
1675     );
1676
1677     write_srclink(cx, item, w);
1678     w.write_str("</div>");
1679 }
1680
1681 pub(crate) fn render_impl_summary(
1682     w: &mut Buffer,
1683     cx: &Context<'_>,
1684     i: &Impl,
1685     parent: &clean::Item,
1686     containing_item: &clean::Item,
1687     show_def_docs: bool,
1688     use_absolute: Option<bool>,
1689     is_on_foreign_type: bool,
1690     // This argument is used to reference same type with different paths to avoid duplication
1691     // in documentation pages for trait with automatic implementations like "Send" and "Sync".
1692     aliases: &[String],
1693 ) {
1694     let id = cx.derive_id(match i.inner_impl().trait_ {
1695         Some(ref t) => {
1696             if is_on_foreign_type {
1697                 get_id_for_impl_on_foreign_type(&i.inner_impl().for_, t, cx)
1698             } else {
1699                 format!("impl-{}", small_url_encode(format!("{:#}", t.print(cx))))
1700             }
1701         }
1702         None => "impl".to_string(),
1703     });
1704     let aliases = if aliases.is_empty() {
1705         String::new()
1706     } else {
1707         format!(" data-aliases=\"{}\"", aliases.join(","))
1708     };
1709     write!(w, "<div id=\"{}\" class=\"impl has-srclink\"{}>", id, aliases);
1710     render_rightside(w, cx, &i.impl_item, containing_item);
1711     write!(w, "<a href=\"#{}\" class=\"anchor\"></a>", id);
1712     write!(w, "<h3 class=\"code-header in-band\">");
1713
1714     if let Some(use_absolute) = use_absolute {
1715         write!(w, "{}", i.inner_impl().print(use_absolute, cx));
1716         if show_def_docs {
1717             for it in &i.inner_impl().items {
1718                 if let clean::TypedefItem(ref tydef, _) = *it.kind {
1719                     w.write_str("<span class=\"where fmt-newline\">  ");
1720                     assoc_type(w, it, &[], Some(&tydef.type_), AssocItemLink::Anchor(None), "", cx);
1721                     w.write_str(";</span>");
1722                 }
1723             }
1724         }
1725     } else {
1726         write!(w, "{}", i.inner_impl().print(false, cx));
1727     }
1728     write!(w, "</h3>");
1729
1730     let is_trait = i.inner_impl().trait_.is_some();
1731     if is_trait {
1732         if let Some(portability) = portability(&i.impl_item, Some(parent)) {
1733             write!(w, "<div class=\"item-info\">{}</div>", portability);
1734         }
1735     }
1736
1737     w.write_str("</div>");
1738 }
1739
1740 fn print_sidebar(cx: &Context<'_>, it: &clean::Item, buffer: &mut Buffer) {
1741     let parentlen = cx.current.len() - if it.is_mod() { 1 } else { 0 };
1742
1743     if it.is_struct()
1744         || it.is_trait()
1745         || it.is_primitive()
1746         || it.is_union()
1747         || it.is_enum()
1748         || it.is_mod()
1749         || it.is_typedef()
1750     {
1751         write!(
1752             buffer,
1753             "<h2 class=\"location\">{}{}</h2>",
1754             match *it.kind {
1755                 clean::StructItem(..) => "Struct ",
1756                 clean::TraitItem(..) => "Trait ",
1757                 clean::PrimitiveItem(..) => "Primitive Type ",
1758                 clean::UnionItem(..) => "Union ",
1759                 clean::EnumItem(..) => "Enum ",
1760                 clean::TypedefItem(..) => "Type Definition ",
1761                 clean::ForeignTypeItem => "Foreign Type ",
1762                 clean::ModuleItem(..) =>
1763                     if it.is_crate() {
1764                         "Crate "
1765                     } else {
1766                         "Module "
1767                     },
1768                 _ => "",
1769             },
1770             it.name.as_ref().unwrap()
1771         );
1772     }
1773
1774     if it.is_crate() {
1775         if let Some(ref version) = cx.cache().crate_version {
1776             write!(
1777                 buffer,
1778                 "<div class=\"block version\">\
1779                      <div class=\"narrow-helper\"></div>\
1780                      <p>Version {}</p>\
1781                  </div>",
1782                 Escape(version),
1783             );
1784         }
1785     }
1786
1787     buffer.write_str("<div class=\"sidebar-elems\">");
1788     if it.is_crate() {
1789         write!(
1790             buffer,
1791             "<a id=\"all-types\" href=\"all.html\"><p>See all {}'s items</p></a>",
1792             it.name.as_ref().expect("crates always have a name"),
1793         );
1794     }
1795
1796     match *it.kind {
1797         clean::StructItem(ref s) => sidebar_struct(cx, buffer, it, s),
1798         clean::TraitItem(ref t) => sidebar_trait(cx, buffer, it, t),
1799         clean::PrimitiveItem(_) => sidebar_primitive(cx, buffer, it),
1800         clean::UnionItem(ref u) => sidebar_union(cx, buffer, it, u),
1801         clean::EnumItem(ref e) => sidebar_enum(cx, buffer, it, e),
1802         clean::TypedefItem(_, _) => sidebar_typedef(cx, buffer, it),
1803         clean::ModuleItem(ref m) => sidebar_module(buffer, &m.items),
1804         clean::ForeignTypeItem => sidebar_foreign_type(cx, buffer, it),
1805         _ => {}
1806     }
1807
1808     // The sidebar is designed to display sibling functions, modules and
1809     // other miscellaneous information. since there are lots of sibling
1810     // items (and that causes quadratic growth in large modules),
1811     // we refactor common parts into a shared JavaScript file per module.
1812     // still, we don't move everything into JS because we want to preserve
1813     // as much HTML as possible in order to allow non-JS-enabled browsers
1814     // to navigate the documentation (though slightly inefficiently).
1815
1816     if !it.is_mod() {
1817         buffer.write_str("<h2 class=\"location\">Other items in<br>");
1818         for (i, name) in cx.current.iter().take(parentlen).enumerate() {
1819             if i > 0 {
1820                 buffer.write_str("::<wbr>");
1821             }
1822             write!(
1823                 buffer,
1824                 "<a href=\"{}index.html\">{}</a>",
1825                 &cx.root_path()[..(cx.current.len() - i - 1) * 3],
1826                 *name
1827             );
1828         }
1829         buffer.write_str("</h2>");
1830     }
1831
1832     // Sidebar refers to the enclosing module, not this module.
1833     let relpath = if it.is_mod() && parentlen != 0 { "./" } else { "" };
1834     write!(
1835         buffer,
1836         "<div id=\"sidebar-vars\" data-name=\"{name}\" data-ty=\"{ty}\" data-relpath=\"{path}\">\
1837         </div>",
1838         name = it.name.unwrap_or(kw::Empty),
1839         ty = it.type_(),
1840         path = relpath
1841     );
1842     write!(buffer, "<script defer src=\"{}sidebar-items.js\"></script>", relpath);
1843     // Closes sidebar-elems div.
1844     buffer.write_str("</div>");
1845 }
1846
1847 fn get_next_url(used_links: &mut FxHashSet<String>, url: String) -> String {
1848     if used_links.insert(url.clone()) {
1849         return url;
1850     }
1851     let mut add = 1;
1852     while !used_links.insert(format!("{}-{}", url, add)) {
1853         add += 1;
1854     }
1855     format!("{}-{}", url, add)
1856 }
1857
1858 struct SidebarLink {
1859     name: Symbol,
1860     url: String,
1861 }
1862
1863 impl fmt::Display for SidebarLink {
1864     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1865         write!(f, "<a href=\"#{}\">{}</a>", self.url, self.name)
1866     }
1867 }
1868
1869 impl PartialEq for SidebarLink {
1870     fn eq(&self, other: &Self) -> bool {
1871         self.url == other.url
1872     }
1873 }
1874
1875 impl Eq for SidebarLink {}
1876
1877 impl PartialOrd for SidebarLink {
1878     fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
1879         Some(self.cmp(other))
1880     }
1881 }
1882
1883 impl Ord for SidebarLink {
1884     fn cmp(&self, other: &Self) -> std::cmp::Ordering {
1885         self.url.cmp(&other.url)
1886     }
1887 }
1888
1889 fn get_methods(
1890     i: &clean::Impl,
1891     for_deref: bool,
1892     used_links: &mut FxHashSet<String>,
1893     deref_mut: bool,
1894     tcx: TyCtxt<'_>,
1895 ) -> Vec<SidebarLink> {
1896     i.items
1897         .iter()
1898         .filter_map(|item| match item.name {
1899             Some(name) if !name.is_empty() && item.is_method() => {
1900                 if !for_deref || should_render_item(item, deref_mut, tcx) {
1901                     Some(SidebarLink {
1902                         name,
1903                         url: get_next_url(used_links, format!("method.{}", name)),
1904                     })
1905                 } else {
1906                     None
1907                 }
1908             }
1909             _ => None,
1910         })
1911         .collect::<Vec<_>>()
1912 }
1913
1914 fn get_associated_constants(
1915     i: &clean::Impl,
1916     used_links: &mut FxHashSet<String>,
1917 ) -> Vec<SidebarLink> {
1918     i.items
1919         .iter()
1920         .filter_map(|item| match item.name {
1921             Some(name) if !name.is_empty() && item.is_associated_const() => Some(SidebarLink {
1922                 name,
1923                 url: get_next_url(used_links, format!("associatedconstant.{}", name)),
1924             }),
1925             _ => None,
1926         })
1927         .collect::<Vec<_>>()
1928 }
1929
1930 // The point is to url encode any potential character from a type with genericity.
1931 fn small_url_encode(s: String) -> String {
1932     let mut st = String::new();
1933     let mut last_match = 0;
1934     for (idx, c) in s.char_indices() {
1935         let escaped = match c {
1936             '<' => "%3C",
1937             '>' => "%3E",
1938             ' ' => "%20",
1939             '?' => "%3F",
1940             '\'' => "%27",
1941             '&' => "%26",
1942             ',' => "%2C",
1943             ':' => "%3A",
1944             ';' => "%3B",
1945             '[' => "%5B",
1946             ']' => "%5D",
1947             '"' => "%22",
1948             _ => continue,
1949         };
1950
1951         st += &s[last_match..idx];
1952         st += escaped;
1953         // NOTE: we only expect single byte characters here - which is fine as long as we
1954         // only match single byte characters
1955         last_match = idx + 1;
1956     }
1957
1958     if last_match != 0 {
1959         st += &s[last_match..];
1960         st
1961     } else {
1962         s
1963     }
1964 }
1965
1966 fn sidebar_assoc_items(cx: &Context<'_>, out: &mut Buffer, it: &clean::Item) {
1967     let did = it.def_id.expect_def_id();
1968     let cache = cx.cache();
1969     if let Some(v) = cache.impls.get(&did) {
1970         let mut used_links = FxHashSet::default();
1971
1972         {
1973             let used_links_bor = &mut used_links;
1974             let mut assoc_consts = v
1975                 .iter()
1976                 .flat_map(|i| get_associated_constants(i.inner_impl(), used_links_bor))
1977                 .collect::<Vec<_>>();
1978             if !assoc_consts.is_empty() {
1979                 // We want links' order to be reproducible so we don't use unstable sort.
1980                 assoc_consts.sort();
1981
1982                 out.push_str(
1983                     "<h3 class=\"sidebar-title\">\
1984                         <a href=\"#implementations\">Associated Constants</a>\
1985                      </h3>\
1986                      <div class=\"sidebar-links\">",
1987                 );
1988                 for line in assoc_consts {
1989                     write!(out, "{}", line);
1990                 }
1991                 out.push_str("</div>");
1992             }
1993             let mut methods = v
1994                 .iter()
1995                 .filter(|i| i.inner_impl().trait_.is_none())
1996                 .flat_map(|i| get_methods(i.inner_impl(), false, used_links_bor, false, cx.tcx()))
1997                 .collect::<Vec<_>>();
1998             if !methods.is_empty() {
1999                 // We want links' order to be reproducible so we don't use unstable sort.
2000                 methods.sort();
2001
2002                 out.push_str(
2003                     "<h3 class=\"sidebar-title\"><a href=\"#implementations\">Methods</a></h3>\
2004                      <div class=\"sidebar-links\">",
2005                 );
2006                 for line in methods {
2007                     write!(out, "{}", line);
2008                 }
2009                 out.push_str("</div>");
2010             }
2011         }
2012
2013         if v.iter().any(|i| i.inner_impl().trait_.is_some()) {
2014             if let Some(impl_) =
2015                 v.iter().find(|i| i.trait_did() == cx.tcx().lang_items().deref_trait())
2016             {
2017                 let mut derefs = FxHashSet::default();
2018                 derefs.insert(did);
2019                 sidebar_deref_methods(cx, out, impl_, v, &mut derefs);
2020             }
2021
2022             let format_impls = |impls: Vec<&Impl>| {
2023                 let mut links = FxHashSet::default();
2024
2025                 let mut ret = impls
2026                     .iter()
2027                     .filter_map(|it| {
2028                         if let Some(ref i) = it.inner_impl().trait_ {
2029                             let i_display = format!("{:#}", i.print(cx));
2030                             let out = Escape(&i_display);
2031                             let encoded = small_url_encode(format!("{:#}", i.print(cx)));
2032                             let prefix = match it.inner_impl().polarity {
2033                                 ty::ImplPolarity::Positive | ty::ImplPolarity::Reservation => "",
2034                                 ty::ImplPolarity::Negative => "!",
2035                             };
2036                             let generated =
2037                                 format!("<a href=\"#impl-{}\">{}{}</a>", encoded, prefix, out);
2038                             if links.insert(generated.clone()) { Some(generated) } else { None }
2039                         } else {
2040                             None
2041                         }
2042                     })
2043                     .collect::<Vec<String>>();
2044                 ret.sort();
2045                 ret
2046             };
2047
2048             let write_sidebar_links = |out: &mut Buffer, links: Vec<String>| {
2049                 out.push_str("<div class=\"sidebar-links\">");
2050                 for link in links {
2051                     out.push_str(&link);
2052                 }
2053                 out.push_str("</div>");
2054             };
2055
2056             let (synthetic, concrete): (Vec<&Impl>, Vec<&Impl>) =
2057                 v.iter().partition::<Vec<_>, _>(|i| i.inner_impl().kind.is_auto());
2058             let (blanket_impl, concrete): (Vec<&Impl>, Vec<&Impl>) =
2059                 concrete.into_iter().partition::<Vec<_>, _>(|i| i.inner_impl().kind.is_blanket());
2060
2061             let concrete_format = format_impls(concrete);
2062             let synthetic_format = format_impls(synthetic);
2063             let blanket_format = format_impls(blanket_impl);
2064
2065             if !concrete_format.is_empty() {
2066                 out.push_str(
2067                     "<h3 class=\"sidebar-title\"><a href=\"#trait-implementations\">\
2068                         Trait Implementations</a></h3>",
2069                 );
2070                 write_sidebar_links(out, concrete_format);
2071             }
2072
2073             if !synthetic_format.is_empty() {
2074                 out.push_str(
2075                     "<h3 class=\"sidebar-title\"><a href=\"#synthetic-implementations\">\
2076                         Auto Trait Implementations</a></h3>",
2077                 );
2078                 write_sidebar_links(out, synthetic_format);
2079             }
2080
2081             if !blanket_format.is_empty() {
2082                 out.push_str(
2083                     "<h3 class=\"sidebar-title\"><a href=\"#blanket-implementations\">\
2084                         Blanket Implementations</a></h3>",
2085                 );
2086                 write_sidebar_links(out, blanket_format);
2087             }
2088         }
2089     }
2090 }
2091
2092 fn sidebar_deref_methods(
2093     cx: &Context<'_>,
2094     out: &mut Buffer,
2095     impl_: &Impl,
2096     v: &[Impl],
2097     derefs: &mut FxHashSet<DefId>,
2098 ) {
2099     let c = cx.cache();
2100
2101     debug!("found Deref: {:?}", impl_);
2102     if let Some((target, real_target)) =
2103         impl_.inner_impl().items.iter().find_map(|item| match *item.kind {
2104             clean::TypedefItem(ref t, true) => Some(match *t {
2105                 clean::Typedef { item_type: Some(ref type_), .. } => (type_, &t.type_),
2106                 _ => (&t.type_, &t.type_),
2107             }),
2108             _ => None,
2109         })
2110     {
2111         debug!("found target, real_target: {:?} {:?}", target, real_target);
2112         if let Some(did) = target.def_id(c) {
2113             if let Some(type_did) = impl_.inner_impl().for_.def_id(c) {
2114                 // `impl Deref<Target = S> for S`
2115                 if did == type_did || !derefs.insert(did) {
2116                     // Avoid infinite cycles
2117                     return;
2118                 }
2119             }
2120         }
2121         let deref_mut = v.iter().any(|i| i.trait_did() == cx.tcx().lang_items().deref_mut_trait());
2122         let inner_impl = target
2123             .def_id(c)
2124             .or_else(|| {
2125                 target.primitive_type().and_then(|prim| c.primitive_locations.get(&prim).cloned())
2126             })
2127             .and_then(|did| c.impls.get(&did));
2128         if let Some(impls) = inner_impl {
2129             debug!("found inner_impl: {:?}", impls);
2130             let mut used_links = FxHashSet::default();
2131             let mut ret = impls
2132                 .iter()
2133                 .filter(|i| i.inner_impl().trait_.is_none())
2134                 .flat_map(|i| {
2135                     get_methods(i.inner_impl(), true, &mut used_links, deref_mut, cx.tcx())
2136                 })
2137                 .collect::<Vec<_>>();
2138             if !ret.is_empty() {
2139                 let map;
2140                 let id = if let Some(target_def_id) = real_target.def_id(c) {
2141                     map = cx.deref_id_map.borrow();
2142                     map.get(&target_def_id).expect("Deref section without derived id")
2143                 } else {
2144                     "deref-methods"
2145                 };
2146                 write!(
2147                     out,
2148                     "<h3 class=\"sidebar-title\"><a href=\"#{}\">Methods from {}&lt;Target={}&gt;</a></h3>",
2149                     id,
2150                     Escape(&format!("{:#}", impl_.inner_impl().trait_.as_ref().unwrap().print(cx))),
2151                     Escape(&format!("{:#}", real_target.print(cx))),
2152                 );
2153                 // We want links' order to be reproducible so we don't use unstable sort.
2154                 ret.sort();
2155                 out.push_str("<div class=\"sidebar-links\">");
2156                 for link in ret {
2157                     write!(out, "{}", link);
2158                 }
2159                 out.push_str("</div>");
2160             }
2161         }
2162
2163         // Recurse into any further impls that might exist for `target`
2164         if let Some(target_did) = target.def_id(c) {
2165             if let Some(target_impls) = c.impls.get(&target_did) {
2166                 if let Some(target_deref_impl) = target_impls.iter().find(|i| {
2167                     i.inner_impl()
2168                         .trait_
2169                         .as_ref()
2170                         .map(|t| Some(t.def_id()) == cx.tcx().lang_items().deref_trait())
2171                         .unwrap_or(false)
2172                 }) {
2173                     sidebar_deref_methods(cx, out, target_deref_impl, target_impls, derefs);
2174                 }
2175             }
2176         }
2177     }
2178 }
2179
2180 fn sidebar_struct(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item, s: &clean::Struct) {
2181     let mut sidebar = Buffer::new();
2182     let fields = get_struct_fields_name(&s.fields);
2183
2184     if !fields.is_empty() {
2185         if let CtorKind::Fictive = s.struct_type {
2186             sidebar.push_str(
2187                 "<h3 class=\"sidebar-title\"><a href=\"#fields\">Fields</a></h3>\
2188                 <div class=\"sidebar-links\">",
2189             );
2190
2191             for field in fields {
2192                 sidebar.push_str(&field);
2193             }
2194
2195             sidebar.push_str("</div>");
2196         } else if let CtorKind::Fn = s.struct_type {
2197             sidebar
2198                 .push_str("<h3 class=\"sidebar-title\"><a href=\"#fields\">Tuple Fields</a></h3>");
2199         }
2200     }
2201
2202     sidebar_assoc_items(cx, &mut sidebar, it);
2203
2204     if !sidebar.is_empty() {
2205         write!(buf, "<div class=\"block items\">{}</div>", sidebar.into_inner());
2206     }
2207 }
2208
2209 fn get_id_for_impl_on_foreign_type(
2210     for_: &clean::Type,
2211     trait_: &clean::Path,
2212     cx: &Context<'_>,
2213 ) -> String {
2214     small_url_encode(format!("impl-{:#}-for-{:#}", trait_.print(cx), for_.print(cx)))
2215 }
2216
2217 fn extract_for_impl_name(item: &clean::Item, cx: &Context<'_>) -> Option<(String, String)> {
2218     match *item.kind {
2219         clean::ItemKind::ImplItem(ref i) => {
2220             i.trait_.as_ref().map(|trait_| {
2221                 // Alternative format produces no URLs,
2222                 // so this parameter does nothing.
2223                 (
2224                     format!("{:#}", i.for_.print(cx)),
2225                     get_id_for_impl_on_foreign_type(&i.for_, trait_, cx),
2226                 )
2227             })
2228         }
2229         _ => None,
2230     }
2231 }
2232
2233 fn sidebar_trait(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item, t: &clean::Trait) {
2234     buf.write_str("<div class=\"block items\">");
2235
2236     fn print_sidebar_section(
2237         out: &mut Buffer,
2238         items: &[clean::Item],
2239         before: &str,
2240         filter: impl Fn(&clean::Item) -> bool,
2241         write: impl Fn(&mut Buffer, &str),
2242         after: &str,
2243     ) {
2244         let mut items = items
2245             .iter()
2246             .filter_map(|m| match m.name {
2247                 Some(ref name) if filter(m) => Some(name.as_str()),
2248                 _ => None,
2249             })
2250             .collect::<Vec<_>>();
2251
2252         if !items.is_empty() {
2253             items.sort_unstable();
2254             out.push_str(before);
2255             for item in items.into_iter() {
2256                 write(out, &item);
2257             }
2258             out.push_str(after);
2259         }
2260     }
2261
2262     print_sidebar_section(
2263         buf,
2264         &t.items,
2265         "<h3 class=\"sidebar-title\"><a href=\"#associated-types\">\
2266             Associated Types</a></h3><div class=\"sidebar-links\">",
2267         |m| m.is_associated_type(),
2268         |out, sym| write!(out, "<a href=\"#associatedtype.{0}\">{0}</a>", sym),
2269         "</div>",
2270     );
2271
2272     print_sidebar_section(
2273         buf,
2274         &t.items,
2275         "<h3 class=\"sidebar-title\"><a href=\"#associated-const\">\
2276             Associated Constants</a></h3><div class=\"sidebar-links\">",
2277         |m| m.is_associated_const(),
2278         |out, sym| write!(out, "<a href=\"#associatedconstant.{0}\">{0}</a>", sym),
2279         "</div>",
2280     );
2281
2282     print_sidebar_section(
2283         buf,
2284         &t.items,
2285         "<h3 class=\"sidebar-title\"><a href=\"#required-methods\">\
2286             Required Methods</a></h3><div class=\"sidebar-links\">",
2287         |m| m.is_ty_method(),
2288         |out, sym| write!(out, "<a href=\"#tymethod.{0}\">{0}</a>", sym),
2289         "</div>",
2290     );
2291
2292     print_sidebar_section(
2293         buf,
2294         &t.items,
2295         "<h3 class=\"sidebar-title\"><a href=\"#provided-methods\">\
2296             Provided Methods</a></h3><div class=\"sidebar-links\">",
2297         |m| m.is_method(),
2298         |out, sym| write!(out, "<a href=\"#method.{0}\">{0}</a>", sym),
2299         "</div>",
2300     );
2301
2302     let cache = cx.cache();
2303     if let Some(implementors) = cache.implementors.get(&it.def_id.expect_def_id()) {
2304         let mut res = implementors
2305             .iter()
2306             .filter(|i| {
2307                 i.inner_impl().for_.def_id(cache).map_or(false, |d| !cache.paths.contains_key(&d))
2308             })
2309             .filter_map(|i| extract_for_impl_name(&i.impl_item, cx))
2310             .collect::<Vec<_>>();
2311
2312         if !res.is_empty() {
2313             res.sort();
2314             buf.push_str(
2315                 "<h3 class=\"sidebar-title\"><a href=\"#foreign-impls\">\
2316                     Implementations on Foreign Types</a></h3>\
2317                  <div class=\"sidebar-links\">",
2318             );
2319             for (name, id) in res.into_iter() {
2320                 write!(buf, "<a href=\"#{}\">{}</a>", id, Escape(&name));
2321             }
2322             buf.push_str("</div>");
2323         }
2324     }
2325
2326     sidebar_assoc_items(cx, buf, it);
2327
2328     buf.push_str("<h3 class=\"sidebar-title\"><a href=\"#implementors\">Implementors</a></h3>");
2329     if t.is_auto {
2330         buf.push_str(
2331             "<h3 class=\"sidebar-title\"><a \
2332                 href=\"#synthetic-implementors\">Auto Implementors</a></h3>",
2333         );
2334     }
2335
2336     buf.push_str("</div>")
2337 }
2338
2339 fn sidebar_primitive(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item) {
2340     let mut sidebar = Buffer::new();
2341     sidebar_assoc_items(cx, &mut sidebar, it);
2342
2343     if !sidebar.is_empty() {
2344         write!(buf, "<div class=\"block items\">{}</div>", sidebar.into_inner());
2345     }
2346 }
2347
2348 fn sidebar_typedef(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item) {
2349     let mut sidebar = Buffer::new();
2350     sidebar_assoc_items(cx, &mut sidebar, it);
2351
2352     if !sidebar.is_empty() {
2353         write!(buf, "<div class=\"block items\">{}</div>", sidebar.into_inner());
2354     }
2355 }
2356
2357 fn get_struct_fields_name(fields: &[clean::Item]) -> Vec<String> {
2358     let mut fields = fields
2359         .iter()
2360         .filter(|f| matches!(*f.kind, clean::StructFieldItem(..)))
2361         .filter_map(|f| {
2362             f.name.map(|name| format!("<a href=\"#structfield.{name}\">{name}</a>", name = name))
2363         })
2364         .collect::<Vec<_>>();
2365     fields.sort();
2366     fields
2367 }
2368
2369 fn sidebar_union(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item, u: &clean::Union) {
2370     let mut sidebar = Buffer::new();
2371     let fields = get_struct_fields_name(&u.fields);
2372
2373     if !fields.is_empty() {
2374         sidebar.push_str(
2375             "<h3 class=\"sidebar-title\"><a href=\"#fields\">Fields</a></h3>\
2376             <div class=\"sidebar-links\">",
2377         );
2378
2379         for field in fields {
2380             sidebar.push_str(&field);
2381         }
2382
2383         sidebar.push_str("</div>");
2384     }
2385
2386     sidebar_assoc_items(cx, &mut sidebar, it);
2387
2388     if !sidebar.is_empty() {
2389         write!(buf, "<div class=\"block items\">{}</div>", sidebar.into_inner());
2390     }
2391 }
2392
2393 fn sidebar_enum(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item, e: &clean::Enum) {
2394     let mut sidebar = Buffer::new();
2395
2396     let mut variants = e
2397         .variants
2398         .iter()
2399         .filter_map(|v| {
2400             v.name
2401                 .as_ref()
2402                 .map(|name| format!("<a href=\"#variant.{name}\">{name}</a>", name = name))
2403         })
2404         .collect::<Vec<_>>();
2405     if !variants.is_empty() {
2406         variants.sort_unstable();
2407         sidebar.push_str(&format!(
2408             "<h3 class=\"sidebar-title\"><a href=\"#variants\">Variants</a></h3>\
2409              <div class=\"sidebar-links\">{}</div>",
2410             variants.join(""),
2411         ));
2412     }
2413
2414     sidebar_assoc_items(cx, &mut sidebar, it);
2415
2416     if !sidebar.is_empty() {
2417         write!(buf, "<div class=\"block items\">{}</div>", sidebar.into_inner());
2418     }
2419 }
2420
2421 fn item_ty_to_strs(ty: ItemType) -> (&'static str, &'static str) {
2422     match ty {
2423         ItemType::ExternCrate | ItemType::Import => ("reexports", "Re-exports"),
2424         ItemType::Module => ("modules", "Modules"),
2425         ItemType::Struct => ("structs", "Structs"),
2426         ItemType::Union => ("unions", "Unions"),
2427         ItemType::Enum => ("enums", "Enums"),
2428         ItemType::Function => ("functions", "Functions"),
2429         ItemType::Typedef => ("types", "Type Definitions"),
2430         ItemType::Static => ("statics", "Statics"),
2431         ItemType::Constant => ("constants", "Constants"),
2432         ItemType::Trait => ("traits", "Traits"),
2433         ItemType::Impl => ("impls", "Implementations"),
2434         ItemType::TyMethod => ("tymethods", "Type Methods"),
2435         ItemType::Method => ("methods", "Methods"),
2436         ItemType::StructField => ("fields", "Struct Fields"),
2437         ItemType::Variant => ("variants", "Variants"),
2438         ItemType::Macro => ("macros", "Macros"),
2439         ItemType::Primitive => ("primitives", "Primitive Types"),
2440         ItemType::AssocType => ("associated-types", "Associated Types"),
2441         ItemType::AssocConst => ("associated-consts", "Associated Constants"),
2442         ItemType::ForeignType => ("foreign-types", "Foreign Types"),
2443         ItemType::Keyword => ("keywords", "Keywords"),
2444         ItemType::OpaqueTy => ("opaque-types", "Opaque Types"),
2445         ItemType::ProcAttribute => ("attributes", "Attribute Macros"),
2446         ItemType::ProcDerive => ("derives", "Derive Macros"),
2447         ItemType::TraitAlias => ("trait-aliases", "Trait aliases"),
2448         ItemType::Generic => unreachable!(),
2449     }
2450 }
2451
2452 fn sidebar_module(buf: &mut Buffer, items: &[clean::Item]) {
2453     let mut sidebar = String::new();
2454
2455     // Re-exports are handled a bit differently because they can be extern crates or imports.
2456     if items.iter().any(|it| {
2457         it.name.is_some()
2458             && (it.type_() == ItemType::ExternCrate
2459                 || (it.type_() == ItemType::Import && !it.is_stripped()))
2460     }) {
2461         let (id, name) = item_ty_to_strs(ItemType::Import);
2462         sidebar.push_str(&format!("<li><a href=\"#{}\">{}</a></li>", id, name));
2463     }
2464
2465     // ordering taken from item_module, reorder, where it prioritized elements in a certain order
2466     // to print its headings
2467     for &myty in &[
2468         ItemType::Primitive,
2469         ItemType::Module,
2470         ItemType::Macro,
2471         ItemType::Struct,
2472         ItemType::Enum,
2473         ItemType::Constant,
2474         ItemType::Static,
2475         ItemType::Trait,
2476         ItemType::Function,
2477         ItemType::Typedef,
2478         ItemType::Union,
2479         ItemType::Impl,
2480         ItemType::TyMethod,
2481         ItemType::Method,
2482         ItemType::StructField,
2483         ItemType::Variant,
2484         ItemType::AssocType,
2485         ItemType::AssocConst,
2486         ItemType::ForeignType,
2487         ItemType::Keyword,
2488     ] {
2489         if items.iter().any(|it| !it.is_stripped() && it.type_() == myty && it.name.is_some()) {
2490             let (id, name) = item_ty_to_strs(myty);
2491             sidebar.push_str(&format!("<li><a href=\"#{}\">{}</a></li>", id, name));
2492         }
2493     }
2494
2495     if !sidebar.is_empty() {
2496         write!(buf, "<div class=\"block items\"><ul>{}</ul></div>", sidebar);
2497     }
2498 }
2499
2500 fn sidebar_foreign_type(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item) {
2501     let mut sidebar = Buffer::new();
2502     sidebar_assoc_items(cx, &mut sidebar, it);
2503
2504     if !sidebar.is_empty() {
2505         write!(buf, "<div class=\"block items\">{}</div>", sidebar.into_inner());
2506     }
2507 }
2508
2509 crate const BASIC_KEYWORDS: &str = "rust, rustlang, rust-lang";
2510
2511 /// Returns a list of all paths used in the type.
2512 /// This is used to help deduplicate imported impls
2513 /// for reexported types. If any of the contained
2514 /// types are re-exported, we don't use the corresponding
2515 /// entry from the js file, as inlining will have already
2516 /// picked up the impl
2517 fn collect_paths_for_type(first_ty: clean::Type, cache: &Cache) -> Vec<String> {
2518     let mut out = Vec::new();
2519     let mut visited = FxHashSet::default();
2520     let mut work = VecDeque::new();
2521
2522     let mut process_path = |did: DefId| {
2523         let get_extern = || cache.external_paths.get(&did).map(|s| s.0.clone());
2524         let fqp = cache.exact_paths.get(&did).cloned().or_else(get_extern);
2525
2526         if let Some(path) = fqp {
2527             out.push(path.join("::"));
2528         }
2529     };
2530
2531     work.push_back(first_ty);
2532
2533     while let Some(ty) = work.pop_front() {
2534         if !visited.insert(ty.clone()) {
2535             continue;
2536         }
2537
2538         match ty {
2539             clean::Type::ResolvedPath { did, .. } => process_path(did),
2540             clean::Type::Tuple(tys) => {
2541                 work.extend(tys.into_iter());
2542             }
2543             clean::Type::Slice(ty) => {
2544                 work.push_back(*ty);
2545             }
2546             clean::Type::Array(ty, _) => {
2547                 work.push_back(*ty);
2548             }
2549             clean::Type::RawPointer(_, ty) => {
2550                 work.push_back(*ty);
2551             }
2552             clean::Type::BorrowedRef { type_, .. } => {
2553                 work.push_back(*type_);
2554             }
2555             clean::Type::QPath { self_type, trait_, .. } => {
2556                 work.push_back(*self_type);
2557                 process_path(trait_.def_id());
2558             }
2559             _ => {}
2560         }
2561     }
2562     out
2563 }
2564
2565 const MAX_FULL_EXAMPLES: usize = 5;
2566 const NUM_VISIBLE_LINES: usize = 10;
2567
2568 /// Generates the HTML for example call locations generated via the --scrape-examples flag.
2569 fn render_call_locations(w: &mut Buffer, cx: &Context<'_>, item: &clean::Item) {
2570     let tcx = cx.tcx();
2571     let def_id = item.def_id.expect_def_id();
2572     let key = tcx.def_path_hash(def_id);
2573     let call_locations = match cx.shared.call_locations.get(&key) {
2574         Some(call_locations) => call_locations,
2575         _ => {
2576             return;
2577         }
2578     };
2579
2580     // Generate a unique ID so users can link to this section for a given method
2581     let id = cx.id_map.borrow_mut().derive("scraped-examples");
2582     write!(
2583         w,
2584         "<div class=\"docblock scraped-example-list\">\
2585           <span></span>\
2586           <h5 id=\"{id}\" class=\"section-header\">\
2587              <a href=\"#{id}\">Examples found in repository</a>\
2588           </h5>",
2589         id = id
2590     );
2591
2592     // Create a URL to a particular location in a reverse-dependency's source file
2593     let link_to_loc = |call_data: &CallData, loc: &CallLocation| -> (String, String) {
2594         let (line_lo, line_hi) = loc.call_expr.line_span;
2595         let (anchor, title) = if line_lo == line_hi {
2596             ((line_lo + 1).to_string(), format!("line {}", line_lo + 1))
2597         } else {
2598             (
2599                 format!("{}-{}", line_lo + 1, line_hi + 1),
2600                 format!("lines {}-{}", line_lo + 1, line_hi + 1),
2601             )
2602         };
2603         let url = format!("{}{}#{}", cx.root_path(), call_data.url, anchor);
2604         (url, title)
2605     };
2606
2607     // Generate the HTML for a single example, being the title and code block
2608     let write_example = |w: &mut Buffer, (path, call_data): (&PathBuf, &CallData)| -> bool {
2609         let contents = match fs::read_to_string(&path) {
2610             Ok(contents) => contents,
2611             Err(err) => {
2612                 let span = item.span(tcx).inner();
2613                 tcx.sess
2614                     .span_err(span, &format!("failed to read file {}: {}", path.display(), err));
2615                 return false;
2616             }
2617         };
2618
2619         // To reduce file sizes, we only want to embed the source code needed to understand the example, not
2620         // the entire file. So we find the smallest byte range that covers all items enclosing examples.
2621         assert!(!call_data.locations.is_empty());
2622         let min_loc =
2623             call_data.locations.iter().min_by_key(|loc| loc.enclosing_item.byte_span.0).unwrap();
2624         let byte_min = min_loc.enclosing_item.byte_span.0;
2625         let line_min = min_loc.enclosing_item.line_span.0;
2626         let max_loc =
2627             call_data.locations.iter().max_by_key(|loc| loc.enclosing_item.byte_span.1).unwrap();
2628         let byte_max = max_loc.enclosing_item.byte_span.1;
2629         let line_max = max_loc.enclosing_item.line_span.1;
2630
2631         // The output code is limited to that byte range.
2632         let contents_subset = &contents[(byte_min as usize)..(byte_max as usize)];
2633
2634         // The call locations need to be updated to reflect that the size of the program has changed.
2635         // Specifically, the ranges are all subtracted by `byte_min` since that's the new zero point.
2636         let (mut byte_ranges, line_ranges): (Vec<_>, Vec<_>) = call_data
2637             .locations
2638             .iter()
2639             .map(|loc| {
2640                 let (byte_lo, byte_hi) = loc.call_expr.byte_span;
2641                 let (line_lo, line_hi) = loc.call_expr.line_span;
2642                 let byte_range = (byte_lo - byte_min, byte_hi - byte_min);
2643                 let line_range = (line_lo - line_min, line_hi - line_min);
2644                 let (line_url, line_title) = link_to_loc(call_data, loc);
2645
2646                 (byte_range, (line_range, line_url, line_title))
2647             })
2648             .unzip();
2649
2650         let (_, init_url, init_title) = &line_ranges[0];
2651         let needs_expansion = line_max - line_min > NUM_VISIBLE_LINES;
2652         let locations_encoded = serde_json::to_string(&line_ranges).unwrap();
2653
2654         write!(
2655             w,
2656             "<div class=\"scraped-example {expanded_cls}\" data-locs=\"{locations}\">\
2657                 <div class=\"scraped-example-title\">\
2658                    {name} (<a href=\"{url}\">{title}</a>)\
2659                 </div>\
2660                 <div class=\"code-wrapper\">",
2661             expanded_cls = if needs_expansion { "" } else { "expanded" },
2662             name = call_data.display_name,
2663             url = init_url,
2664             title = init_title,
2665             // The locations are encoded as a data attribute, so they can be read
2666             // later by the JS for interactions.
2667             locations = Escape(&locations_encoded)
2668         );
2669
2670         if line_ranges.len() > 1 {
2671             write!(w, r#"<span class="prev">&pr;</span> <span class="next">&sc;</span>"#);
2672         }
2673
2674         if needs_expansion {
2675             write!(w, r#"<span class="expand">&varr;</span>"#);
2676         }
2677
2678         // Look for the example file in the source map if it exists, otherwise return a dummy span
2679         let file_span = (|| {
2680             let source_map = tcx.sess.source_map();
2681             let crate_src = tcx.sess.local_crate_source_file.as_ref()?;
2682             let abs_crate_src = crate_src.canonicalize().ok()?;
2683             let crate_root = abs_crate_src.parent()?.parent()?;
2684             let rel_path = path.strip_prefix(crate_root).ok()?;
2685             let files = source_map.files();
2686             let file = files.iter().find(|file| match &file.name {
2687                 FileName::Real(RealFileName::LocalPath(other_path)) => rel_path == other_path,
2688                 _ => false,
2689             })?;
2690             Some(rustc_span::Span::with_root_ctxt(
2691                 file.start_pos + BytePos(byte_min),
2692                 file.start_pos + BytePos(byte_max),
2693             ))
2694         })()
2695         .unwrap_or(rustc_span::DUMMY_SP);
2696
2697         // The root path is the inverse of Context::current
2698         let root_path = vec!["../"; cx.current.len() - 1].join("");
2699
2700         let mut decoration_info = FxHashMap::default();
2701         decoration_info.insert("highlight focus", vec![byte_ranges.remove(0)]);
2702         decoration_info.insert("highlight", byte_ranges);
2703
2704         sources::print_src(
2705             w,
2706             contents_subset,
2707             call_data.edition,
2708             file_span,
2709             cx,
2710             &root_path,
2711             Some(highlight::DecorationInfo(decoration_info)),
2712             sources::SourceContext::Embedded { offset: line_min },
2713         );
2714         write!(w, "</div></div>");
2715
2716         true
2717     };
2718
2719     // The call locations are output in sequence, so that sequence needs to be determined.
2720     // Ideally the most "relevant" examples would be shown first, but there's no general algorithm
2721     // for determining relevance. Instead, we prefer the smallest examples being likely the easiest to
2722     // understand at a glance.
2723     let ordered_locations = {
2724         let sort_criterion = |(_, call_data): &(_, &CallData)| {
2725             // Use the first location because that's what the user will see initially
2726             let (lo, hi) = call_data.locations[0].enclosing_item.byte_span;
2727             hi - lo
2728         };
2729
2730         let mut locs = call_locations.into_iter().collect::<Vec<_>>();
2731         locs.sort_by_key(sort_criterion);
2732         locs
2733     };
2734
2735     let mut it = ordered_locations.into_iter().peekable();
2736
2737     // An example may fail to write if its source can't be read for some reason, so this method
2738     // continues iterating until a write suceeds
2739     let write_and_skip_failure = |w: &mut Buffer, it: &mut Peekable<_>| {
2740         while let Some(example) = it.next() {
2741             if write_example(&mut *w, example) {
2742                 break;
2743             }
2744         }
2745     };
2746
2747     // Write just one example that's visible by default in the method's description.
2748     write_and_skip_failure(w, &mut it);
2749
2750     // Then add the remaining examples in a hidden section.
2751     if it.peek().is_some() {
2752         write!(
2753             w,
2754             "<details class=\"rustdoc-toggle more-examples-toggle\">\
2755                   <summary class=\"hideme\">\
2756                      <span>More examples</span>\
2757                   </summary>\
2758                   <div class=\"more-scraped-examples\">\
2759                     <div class=\"toggle-line\"><div class=\"toggle-line-inner\"></div></div>\
2760                     <div class=\"more-scraped-examples-inner\">"
2761         );
2762
2763         // Only generate inline code for MAX_FULL_EXAMPLES number of examples. Otherwise we could
2764         // make the page arbitrarily huge!
2765         for _ in 0..MAX_FULL_EXAMPLES {
2766             write_and_skip_failure(w, &mut it);
2767         }
2768
2769         // For the remaining examples, generate a <ul> containing links to the source files.
2770         if it.peek().is_some() {
2771             write!(w, r#"<div class="example-links">Additional examples can be found in:<br><ul>"#);
2772             it.for_each(|(_, call_data)| {
2773                 let (url, _) = link_to_loc(&call_data, &call_data.locations[0]);
2774                 write!(
2775                     w,
2776                     r#"<li><a href="{url}">{name}</a></li>"#,
2777                     url = url,
2778                     name = call_data.display_name
2779                 );
2780             });
2781             write!(w, "</ul></div>");
2782         }
2783
2784         write!(w, "</div></div></details>");
2785     }
2786
2787     write!(w, "</div>");
2788 }