src/librustdoc/passes/collect_intra_doc_links.rs

   1 use rustc_ast as ast;
   2 use rustc_data_structures::stable_set::FxHashSet;
   3 use rustc_errors::{Applicability, DiagnosticBuilder};
   4 use rustc_expand::base::SyntaxExtensionKind;
   5 use rustc_feature::UnstableFeatures;
   6 use rustc_hir as hir;
   7 use rustc_hir::def::{
   8     DefKind,
   9     Namespace::{self, *},
  10     PerNS, Res,
  11 };
  12 use rustc_hir::def_id::DefId;
  13 use rustc_middle::ty;
  14 use rustc_resolve::ParentScope;
  15 use rustc_session::lint;
  16 use rustc_span::hygiene::MacroKind;
  17 use rustc_span::symbol::Ident;
  18 use rustc_span::symbol::Symbol;
  19 use rustc_span::DUMMY_SP;
  20 use smallvec::SmallVec;
  21
  22 use std::cell::Cell;
  23 use std::ops::Range;
  24
  25 use crate::clean::*;
  26 use crate::core::DocContext;
  27 use crate::fold::DocFolder;
  28 use crate::html::markdown::markdown_links;
  29 use crate::passes::Pass;
  30
  31 use super::span_of_attrs;
  32
  33 pub const COLLECT_INTRA_DOC_LINKS: Pass = Pass {
  34     name: "collect-intra-doc-links",
  35     run: collect_intra_doc_links,
  36     description: "reads a crate's documentation to resolve intra-doc-links",
  37 };
  38
  39 pub fn collect_intra_doc_links(krate: Crate, cx: &DocContext<'_>) -> Crate {
  40     if !UnstableFeatures::from_environment().is_nightly_build() {
  41         krate
  42     } else {
  43         let mut coll = LinkCollector::new(cx);
  44
  45         coll.fold_crate(krate)
  46     }
  47 }
  48
  49 enum ErrorKind {
  50     ResolutionFailure,
  51     AnchorFailure(AnchorFailure),
  52 }
  53
  54 enum AnchorFailure {
  55     MultipleAnchors,
  56     Primitive,
  57     Variant,
  58     AssocConstant,
  59     AssocType,
  60     Field,
  61     Method,
  62 }
  63
  64 struct LinkCollector<'a, 'tcx> {
  65     cx: &'a DocContext<'tcx>,
  66     // NOTE: this may not necessarily be a module in the current crate
  67     mod_ids: Vec<DefId>,
  68     /// This is used to store the kind of associated items,
  69     /// because `clean` and the disambiguator code expect them to be different.
  70     /// See the code for associated items on inherent impls for details.
  71     kind_side_channel: Cell<Option<DefKind>>,
  72 }
  73
  74 impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
  75     fn new(cx: &'a DocContext<'tcx>) -> Self {
  76         LinkCollector { cx, mod_ids: Vec::new(), kind_side_channel: Cell::new(None) }
  77     }
  78
  79     fn variant_field(
  80         &self,
  81         path_str: &str,
  82         current_item: &Option<String>,
  83         module_id: DefId,
  84     ) -> Result<(Res, Option<String>), ErrorKind> {
  85         let cx = self.cx;
  86
  87         let mut split = path_str.rsplitn(3, "::");
  88         let variant_field_name =
  89             split.next().map(|f| Symbol::intern(f)).ok_or(ErrorKind::ResolutionFailure)?;
  90         let variant_name =
  91             split.next().map(|f| Symbol::intern(f)).ok_or(ErrorKind::ResolutionFailure)?;
  92         let path = split
  93             .next()
  94             .map(|f| {
  95                 if f == "self" || f == "Self" {
  96                     if let Some(name) = current_item.as_ref() {
  97                         return name.clone();
  98                     }
  99                 }
 100                 f.to_owned()
 101             })
 102             .ok_or(ErrorKind::ResolutionFailure)?;
 103         let (_, ty_res) = cx
 104             .enter_resolver(|resolver| {
 105                 resolver.resolve_str_path_error(DUMMY_SP, &path, TypeNS, module_id)
 106             })
 107             .map_err(|_| ErrorKind::ResolutionFailure)?;
 108         if let Res::Err = ty_res {
 109             return Err(ErrorKind::ResolutionFailure);
 110         }
 111         let ty_res = ty_res.map_id(|_| panic!("unexpected node_id"));
 112         match ty_res {
 113             Res::Def(DefKind::Enum, did) => {
 114                 if cx
 115                     .tcx
 116                     .inherent_impls(did)
 117                     .iter()
 118                     .flat_map(|imp| cx.tcx.associated_items(*imp).in_definition_order())
 119                     .any(|item| item.ident.name == variant_name)
 120                 {
 121                     return Err(ErrorKind::ResolutionFailure);
 122                 }
 123                 match cx.tcx.type_of(did).kind {
 124                     ty::Adt(def, _) if def.is_enum() => {
 125                         if def.all_fields().any(|item| item.ident.name == variant_field_name) {
 126                             Ok((
 127                                 ty_res,
 128                                 Some(format!(
 129                                     "variant.{}.field.{}",
 130                                     variant_name, variant_field_name
 131                                 )),
 132                             ))
 133                         } else {
 134                             Err(ErrorKind::ResolutionFailure)
 135                         }
 136                     }
 137                     _ => Err(ErrorKind::ResolutionFailure),
 138                 }
 139             }
 140             _ => Err(ErrorKind::ResolutionFailure),
 141         }
 142     }
 143
 144     /// Resolves a string as a macro.
 145     fn macro_resolve(&self, path_str: &str, parent_id: Option<DefId>) -> Option<Res> {
 146         let cx = self.cx;
 147         let path = ast::Path::from_ident(Ident::from_str(path_str));
 148         cx.enter_resolver(|resolver| {
 149             if let Ok((Some(ext), res)) = resolver.resolve_macro_path(
 150                 &path,
 151                 None,
 152                 &ParentScope::module(resolver.graph_root()),
 153                 false,
 154                 false,
 155             ) {
 156                 if let SyntaxExtensionKind::LegacyBang { .. } = ext.kind {
 157                     return Some(res.map_id(|_| panic!("unexpected id")));
 158                 }
 159             }
 160             if let Some(res) = resolver.all_macros().get(&Symbol::intern(path_str)) {
 161                 return Some(res.map_id(|_| panic!("unexpected id")));
 162             }
 163             if let Some(module_id) = parent_id {
 164                 if let Ok((_, res)) =
 165                     resolver.resolve_str_path_error(DUMMY_SP, path_str, MacroNS, module_id)
 166                 {
 167                     // don't resolve builtins like `#[derive]`
 168                     if let Res::Def(..) = res {
 169                         let res = res.map_id(|_| panic!("unexpected node_id"));
 170                         return Some(res);
 171                     }
 172                 }
 173             } else {
 174                 debug!("attempting to resolve item without parent module: {}", path_str);
 175             }
 176             None
 177         })
 178     }
 179     /// Resolves a string as a path within a particular namespace. Also returns an optional
 180     /// URL fragment in the case of variants and methods.
 181     fn resolve(
 182         &self,
 183         path_str: &str,
 184         ns: Namespace,
 185         current_item: &Option<String>,
 186         parent_id: Option<DefId>,
 187         extra_fragment: &Option<String>,
 188     ) -> Result<(Res, Option<String>), ErrorKind> {
 189         let cx = self.cx;
 190
 191         // In case we're in a module, try to resolve the relative path.
 192         if let Some(module_id) = parent_id {
 193             let result = cx.enter_resolver(|resolver| {
 194                 resolver.resolve_str_path_error(DUMMY_SP, &path_str, ns, module_id)
 195             });
 196             debug!("{} resolved to {:?} in namespace {:?}", path_str, result, ns);
 197             let result = match result {
 198                 Ok((_, Res::Err)) => Err(ErrorKind::ResolutionFailure),
 199                 _ => result.map_err(|_| ErrorKind::ResolutionFailure),
 200             };
 201
 202             if let Ok((_, res)) = result {
 203                 let res = res.map_id(|_| panic!("unexpected node_id"));
 204                 // In case this is a trait item, skip the
 205                 // early return and try looking for the trait.
 206                 let value = match res {
 207                     Res::Def(DefKind::AssocFn | DefKind::AssocConst, _) => true,
 208                     Res::Def(DefKind::AssocTy, _) => false,
 209                     Res::Def(DefKind::Variant, _) => {
 210                         return handle_variant(cx, res, extra_fragment);
 211                     }
 212                     // Not a trait item; just return what we found.
 213                     Res::PrimTy(..) => {
 214                         if extra_fragment.is_some() {
 215                             return Err(ErrorKind::AnchorFailure(AnchorFailure::Primitive));
 216                         }
 217                         return Ok((res, Some(path_str.to_owned())));
 218                     }
 219                     Res::Def(DefKind::Mod, _) => {
 220                         return Ok((res, extra_fragment.clone()));
 221                     }
 222                     _ => {
 223                         return Ok((res, extra_fragment.clone()));
 224                     }
 225                 };
 226
 227                 if value != (ns == ValueNS) {
 228                     return Err(ErrorKind::ResolutionFailure);
 229                 }
 230             } else if let Some((path, prim)) = is_primitive(path_str, ns) {
 231                 if extra_fragment.is_some() {
 232                     return Err(ErrorKind::AnchorFailure(AnchorFailure::Primitive));
 233                 }
 234                 return Ok((prim, Some(path.to_owned())));
 235             }
 236
 237             // Try looking for methods and associated items.
 238             let mut split = path_str.rsplitn(2, "::");
 239             let item_name =
 240                 split.next().map(|f| Symbol::intern(f)).ok_or(ErrorKind::ResolutionFailure)?;
 241             let path = split
 242                 .next()
 243                 .map(|f| {
 244                     if f == "self" || f == "Self" {
 245                         if let Some(name) = current_item.as_ref() {
 246                             return name.clone();
 247                         }
 248                     }
 249                     f.to_owned()
 250                 })
 251                 .ok_or(ErrorKind::ResolutionFailure)?;
 252
 253             if let Some((path, prim)) = is_primitive(&path, TypeNS) {
 254                 for &impl_ in primitive_impl(cx, &path).ok_or(ErrorKind::ResolutionFailure)? {
 255                     let link = cx
 256                         .tcx
 257                         .associated_items(impl_)
 258                         .find_by_name_and_namespace(
 259                             cx.tcx,
 260                             Ident::with_dummy_span(item_name),
 261                             ns,
 262                             impl_,
 263                         )
 264                         .and_then(|item| match item.kind {
 265                             ty::AssocKind::Fn => Some("method"),
 266                             _ => None,
 267                         })
 268                         .map(|out| (prim, Some(format!("{}#{}.{}", path, out, item_name))));
 269                     if let Some(link) = link {
 270                         return Ok(link);
 271                     }
 272                 }
 273                 return Err(ErrorKind::ResolutionFailure);
 274             }
 275
 276             let (_, ty_res) = cx
 277                 .enter_resolver(|resolver| {
 278                     resolver.resolve_str_path_error(DUMMY_SP, &path, TypeNS, module_id)
 279                 })
 280                 .map_err(|_| ErrorKind::ResolutionFailure)?;
 281             if let Res::Err = ty_res {
 282                 return if ns == Namespace::ValueNS {
 283                     self.variant_field(path_str, current_item, module_id)
 284                 } else {
 285                     Err(ErrorKind::ResolutionFailure)
 286                 };
 287             }
 288             let ty_res = ty_res.map_id(|_| panic!("unexpected node_id"));
 289             let res = match ty_res {
 290                 Res::Def(
 291                     DefKind::Struct | DefKind::Union | DefKind::Enum | DefKind::TyAlias,
 292                     did,
 293                 ) => {
 294                     debug!("looking for associated item named {} for item {:?}", item_name, did);
 295                     // Checks if item_name belongs to `impl SomeItem`
 296                     let kind = cx
 297                         .tcx
 298                         .inherent_impls(did)
 299                         .iter()
 300                         .flat_map(|&imp| {
 301                             cx.tcx.associated_items(imp).find_by_name_and_namespace(
 302                                 cx.tcx,
 303                                 Ident::with_dummy_span(item_name),
 304                                 ns,
 305                                 imp,
 306                             )
 307                         })
 308                         .map(|item| item.kind)
 309                         // There should only ever be one associated item that matches from any inherent impl
 310                         .next()
 311                         // Check if item_name belongs to `impl SomeTrait for SomeItem`
 312                         // This gives precedence to `impl SomeItem`:
 313                         // Although having both would be ambiguous, use impl version for compat. sake.
 314                         // To handle that properly resolve() would have to support
 315                         // something like [`ambi_fn`](<SomeStruct as SomeTrait>::ambi_fn)
 316                         .or_else(|| {
 317                             let kind = resolve_associated_trait_item(
 318                                 did, module_id, item_name, ns, &self.cx,
 319                             );
 320                             debug!("got associated item kind {:?}", kind);
 321                             kind
 322                         });
 323
 324                     if let Some(kind) = kind {
 325                         let out = match kind {
 326                             ty::AssocKind::Fn => "method",
 327                             ty::AssocKind::Const => "associatedconstant",
 328                             ty::AssocKind::Type => "associatedtype",
 329                         };
 330                         Some(if extra_fragment.is_some() {
 331                             Err(ErrorKind::AnchorFailure(if kind == ty::AssocKind::Fn {
 332                                 AnchorFailure::Method
 333                             } else {
 334                                 AnchorFailure::AssocConstant
 335                             }))
 336                         } else {
 337                             // HACK(jynelson): `clean` expects the type, not the associated item.
 338                             // but the disambiguator logic expects the associated item.
 339                             // Store the kind in a side channel so that only the disambiguator logic looks at it.
 340                             self.kind_side_channel.set(Some(kind.as_def_kind()));
 341                             Ok((ty_res, Some(format!("{}.{}", out, item_name))))
 342                         })
 343                     } else if ns == Namespace::ValueNS {
 344                         match cx.tcx.type_of(did).kind {
 345                             ty::Adt(def, _) => {
 346                                 let field = if def.is_enum() {
 347                                     def.all_fields().find(|item| item.ident.name == item_name)
 348                                 } else {
 349                                     def.non_enum_variant()
 350                                         .fields
 351                                         .iter()
 352                                         .find(|item| item.ident.name == item_name)
 353                                 };
 354                                 field.map(|item| {
 355                                     if extra_fragment.is_some() {
 356                                         Err(ErrorKind::AnchorFailure(if def.is_enum() {
 357                                             AnchorFailure::Variant
 358                                         } else {
 359                                             AnchorFailure::Field
 360                                         }))
 361                                     } else {
 362                                         Ok((
 363                                             ty_res,
 364                                             Some(format!(
 365                                                 "{}.{}",
 366                                                 if def.is_enum() {
 367                                                     "variant"
 368                                                 } else {
 369                                                     "structfield"
 370                                                 },
 371                                                 item.ident
 372                                             )),
 373                                         ))
 374                                     }
 375                                 })
 376                             }
 377                             _ => None,
 378                         }
 379                     } else {
 380                         // We already know this isn't in ValueNS, so no need to check variant_field
 381                         return Err(ErrorKind::ResolutionFailure);
 382                     }
 383                 }
 384                 Res::Def(DefKind::Trait, did) => cx
 385                     .tcx
 386                     .associated_items(did)
 387                     .find_by_name_and_namespace(cx.tcx, Ident::with_dummy_span(item_name), ns, did)
 388                     .map(|item| {
 389                         let kind = match item.kind {
 390                             ty::AssocKind::Const => "associatedconstant",
 391                             ty::AssocKind::Type => "associatedtype",
 392                             ty::AssocKind::Fn => {
 393                                 if item.defaultness.has_value() {
 394                                     "method"
 395                                 } else {
 396                                     "tymethod"
 397                                 }
 398                             }
 399                         };
 400
 401                         if extra_fragment.is_some() {
 402                             Err(ErrorKind::AnchorFailure(if item.kind == ty::AssocKind::Const {
 403                                 AnchorFailure::AssocConstant
 404                             } else if item.kind == ty::AssocKind::Type {
 405                                 AnchorFailure::AssocType
 406                             } else {
 407                                 AnchorFailure::Method
 408                             }))
 409                         } else {
 410                             let res = Res::Def(item.kind.as_def_kind(), item.def_id);
 411                             Ok((res, Some(format!("{}.{}", kind, item_name))))
 412                         }
 413                     }),
 414                 _ => None,
 415             };
 416             res.unwrap_or_else(|| {
 417                 if ns == Namespace::ValueNS {
 418                     self.variant_field(path_str, current_item, module_id)
 419                 } else {
 420                     Err(ErrorKind::ResolutionFailure)
 421                 }
 422             })
 423         } else {
 424             debug!("attempting to resolve item without parent module: {}", path_str);
 425             Err(ErrorKind::ResolutionFailure)
 426         }
 427     }
 428 }
 429
 430 fn resolve_associated_trait_item(
 431     did: DefId,
 432     module: DefId,
 433     item_name: Symbol,
 434     ns: Namespace,
 435     cx: &DocContext<'_>,
 436 ) -> Option<ty::AssocKind> {
 437     let ty = cx.tcx.type_of(did);
 438     // First consider automatic impls: `impl From<T> for T`
 439     let implicit_impls = crate::clean::get_auto_trait_and_blanket_impls(cx, ty, did);
 440     let mut candidates: Vec<_> = implicit_impls
 441         .flat_map(|impl_outer| {
 442             match impl_outer.inner {
 443                 ImplItem(impl_) => {
 444                     debug!("considering auto or blanket impl for trait {:?}", impl_.trait_);
 445                     // Give precedence to methods that were overridden
 446                     if !impl_.provided_trait_methods.contains(&*item_name.as_str()) {
 447                         let mut items = impl_.items.into_iter().filter_map(|assoc| {
 448                             if assoc.name.as_deref() != Some(&*item_name.as_str()) {
 449                                 return None;
 450                             }
 451                             let kind = assoc
 452                                 .inner
 453                                 .as_assoc_kind()
 454                                 .expect("inner items for a trait should be associated items");
 455                             if kind.namespace() != ns {
 456                                 return None;
 457                             }
 458
 459                             trace!("considering associated item {:?}", assoc.inner);
 460                             // We have a slight issue: normal methods come from `clean` types,
 461                             // but provided methods come directly from `tcx`.
 462                             // Fortunately, we don't need the whole method, we just need to know
 463                             // what kind of associated item it is.
 464                             Some((assoc.def_id, kind))
 465                         });
 466                         let assoc = items.next();
 467                         debug_assert_eq!(items.count(), 0);
 468                         assoc
 469                     } else {
 470                         // These are provided methods or default types:
 471                         // ```
 472                         // trait T {
 473                         //   type A = usize;
 474                         //   fn has_default() -> A { 0 }
 475                         // }
 476                         // ```
 477                         let trait_ = impl_.trait_.unwrap().def_id().unwrap();
 478                         cx.tcx
 479                             .associated_items(trait_)
 480                             .find_by_name_and_namespace(
 481                                 cx.tcx,
 482                                 Ident::with_dummy_span(item_name),
 483                                 ns,
 484                                 trait_,
 485                             )
 486                             .map(|assoc| (assoc.def_id, assoc.kind))
 487                     }
 488                 }
 489                 _ => panic!("get_impls returned something that wasn't an impl"),
 490             }
 491         })
 492         .collect();
 493
 494     // Next consider explicit impls: `impl MyTrait for MyType`
 495     // Give precedence to inherent impls.
 496     if candidates.is_empty() {
 497         let traits = traits_implemented_by(cx, did, module);
 498         debug!("considering traits {:?}", traits);
 499         candidates.extend(traits.iter().filter_map(|&trait_| {
 500             cx.tcx
 501                 .associated_items(trait_)
 502                 .find_by_name_and_namespace(cx.tcx, Ident::with_dummy_span(item_name), ns, trait_)
 503                 .map(|assoc| (assoc.def_id, assoc.kind))
 504         }));
 505     }
 506     // FIXME: warn about ambiguity
 507     debug!("the candidates were {:?}", candidates);
 508     candidates.pop().map(|(_, kind)| kind)
 509 }
 510
 511 /// Given a type, return all traits in scope in `module` implemented by that type.
 512 ///
 513 /// NOTE: this cannot be a query because more traits could be available when more crates are compiled!
 514 /// So it is not stable to serialize cross-crate.
 515 fn traits_implemented_by(cx: &DocContext<'_>, type_: DefId, module: DefId) -> FxHashSet<DefId> {
 516     let mut cache = cx.module_trait_cache.borrow_mut();
 517     let in_scope_traits = cache.entry(module).or_insert_with(|| {
 518         cx.enter_resolver(|resolver| {
 519             resolver.traits_in_scope(module).into_iter().map(|candidate| candidate.def_id).collect()
 520         })
 521     });
 522
 523     let ty = cx.tcx.type_of(type_);
 524     let iter = in_scope_traits.iter().flat_map(|&trait_| {
 525         trace!("considering explicit impl for trait {:?}", trait_);
 526         let mut saw_impl = false;
 527         // Look at each trait implementation to see if it's an impl for `did`
 528         cx.tcx.for_each_relevant_impl(trait_, ty, |impl_| {
 529             // FIXME: this is inefficient, find a way to short-circuit for_each_* so this doesn't take as long
 530             if saw_impl {
 531                 return;
 532             }
 533
 534             let trait_ref = cx.tcx.impl_trait_ref(impl_).expect("this is not an inherent impl");
 535             // Check if these are the same type.
 536             let impl_type = trait_ref.self_ty();
 537             debug!(
 538                 "comparing type {} with kind {:?} against type {:?}",
 539                 impl_type, impl_type.kind, type_
 540             );
 541             // Fast path: if this is a primitive simple `==` will work
 542             saw_impl = impl_type == ty
 543                 || match impl_type.kind {
 544                     // Check if these are the same def_id
 545                     ty::Adt(def, _) => {
 546                         debug!("adt def_id: {:?}", def.did);
 547                         def.did == type_
 548                     }
 549                     ty::Foreign(def_id) => def_id == type_,
 550                     _ => false,
 551                 };
 552         });
 553         if saw_impl { Some(trait_) } else { None }
 554     });
 555     iter.collect()
 556 }
 557
 558 /// Check for resolve collisions between a trait and its derive
 559 ///
 560 /// These are common and we should just resolve to the trait in that case
 561 fn is_derive_trait_collision<T>(ns: &PerNS<Option<(Res, T)>>) -> bool {
 562     if let PerNS {
 563         type_ns: Some((Res::Def(DefKind::Trait, _), _)),
 564         macro_ns: Some((Res::Def(DefKind::Macro(MacroKind::Derive), _), _)),
 565         ..
 566     } = *ns
 567     {
 568         true
 569     } else {
 570         false
 571     }
 572 }
 573
 574 impl<'a, 'tcx> DocFolder for LinkCollector<'a, 'tcx> {
 575     fn fold_item(&mut self, mut item: Item) -> Option<Item> {
 576         use rustc_middle::ty::DefIdTree;
 577
 578         let parent_node = if item.is_fake() {
 579             // FIXME: is this correct?
 580             None
 581         } else {
 582             let mut current = item.def_id;
 583             // The immediate parent might not always be a module.
 584             // Find the first parent which is.
 585             loop {
 586                 if let Some(parent) = self.cx.tcx.parent(current) {
 587                     if self.cx.tcx.def_kind(parent) == DefKind::Mod {
 588                         break Some(parent);
 589                     }
 590                     current = parent;
 591                 } else {
 592                     break None;
 593                 }
 594             }
 595         };
 596
 597         if parent_node.is_some() {
 598             trace!("got parent node for {:?} {:?}, id {:?}", item.type_(), item.name, item.def_id);
 599         }
 600
 601         let current_item = match item.inner {
 602             ModuleItem(..) => {
 603                 if item.attrs.inner_docs {
 604                     if item.def_id.is_top_level_module() { item.name.clone() } else { None }
 605                 } else {
 606                     match parent_node.or(self.mod_ids.last().copied()) {
 607                         Some(parent) if !parent.is_top_level_module() => {
 608                             // FIXME: can we pull the parent module's name from elsewhere?
 609                             Some(self.cx.tcx.item_name(parent).to_string())
 610                         }
 611                         _ => None,
 612                     }
 613                 }
 614             }
 615             ImplItem(Impl { ref for_, .. }) => {
 616                 for_.def_id().map(|did| self.cx.tcx.item_name(did).to_string())
 617             }
 618             // we don't display docs on `extern crate` items anyway, so don't process them.
 619             ExternCrateItem(..) => {
 620                 debug!("ignoring extern crate item {:?}", item.def_id);
 621                 return self.fold_item_recur(item);
 622             }
 623             ImportItem(Import::Simple(ref name, ..)) => Some(name.clone()),
 624             MacroItem(..) => None,
 625             _ => item.name.clone(),
 626         };
 627
 628         if item.is_mod() && item.attrs.inner_docs {
 629             self.mod_ids.push(item.def_id);
 630         }
 631
 632         let cx = self.cx;
 633         let dox = item.attrs.collapsed_doc_value().unwrap_or_else(String::new);
 634         trace!("got documentation '{}'", dox);
 635
 636         // find item's parent to resolve `Self` in item's docs below
 637         let parent_name = self.cx.as_local_hir_id(item.def_id).and_then(|item_hir| {
 638             let parent_hir = self.cx.tcx.hir().get_parent_item(item_hir);
 639             let item_parent = self.cx.tcx.hir().find(parent_hir);
 640             match item_parent {
 641                 Some(hir::Node::Item(hir::Item {
 642                     kind:
 643                         hir::ItemKind::Impl {
 644                             self_ty:
 645                                 hir::Ty {
 646                                     kind:
 647                                         hir::TyKind::Path(hir::QPath::Resolved(
 648                                             _,
 649                                             hir::Path { segments, .. },
 650                                         )),
 651                                     ..
 652                                 },
 653                             ..
 654                         },
 655                     ..
 656                 })) => segments.first().map(|seg| seg.ident.to_string()),
 657                 Some(hir::Node::Item(hir::Item {
 658                     ident, kind: hir::ItemKind::Enum(..), ..
 659                 }))
 660                 | Some(hir::Node::Item(hir::Item {
 661                     ident, kind: hir::ItemKind::Struct(..), ..
 662                 }))
 663                 | Some(hir::Node::Item(hir::Item {
 664                     ident, kind: hir::ItemKind::Union(..), ..
 665                 }))
 666                 | Some(hir::Node::Item(hir::Item {
 667                     ident, kind: hir::ItemKind::Trait(..), ..
 668                 })) => Some(ident.to_string()),
 669                 _ => None,
 670             }
 671         });
 672
 673         for (ori_link, link_range) in markdown_links(&dox) {
 674             trace!("considering link '{}'", ori_link);
 675
 676             // Bail early for real links.
 677             if ori_link.contains('/') {
 678                 continue;
 679             }
 680
 681             // [] is mostly likely not supposed to be a link
 682             if ori_link.is_empty() {
 683                 continue;
 684             }
 685
 686             let link = ori_link.replace("`", "");
 687             let parts = link.split('#').collect::<Vec<_>>();
 688             let (link, extra_fragment) = if parts.len() > 2 {
 689                 anchor_failure(cx, &item, &link, &dox, link_range, AnchorFailure::MultipleAnchors);
 690                 continue;
 691             } else if parts.len() == 2 {
 692                 if parts[0].trim().is_empty() {
 693                     // This is an anchor to an element of the current page, nothing to do in here!
 694                     continue;
 695                 }
 696                 (parts[0].to_owned(), Some(parts[1].to_owned()))
 697             } else {
 698                 (parts[0].to_owned(), None)
 699             };
 700             let resolved_self;
 701             let mut path_str;
 702             let disambiguator;
 703             let (mut res, mut fragment) = {
 704                 path_str = if let Ok((d, path)) = Disambiguator::from_str(&link) {
 705                     disambiguator = Some(d);
 706                     path
 707                 } else {
 708                     disambiguator = None;
 709                     &link
 710                 }
 711                 .trim();
 712
 713                 if path_str.contains(|ch: char| !(ch.is_alphanumeric() || ch == ':' || ch == '_')) {
 714                     continue;
 715                 }
 716
 717                 // In order to correctly resolve intra-doc-links we need to
 718                 // pick a base AST node to work from.  If the documentation for
 719                 // this module came from an inner comment (//!) then we anchor
 720                 // our name resolution *inside* the module.  If, on the other
 721                 // hand it was an outer comment (///) then we anchor the name
 722                 // resolution in the parent module on the basis that the names
 723                 // used are more likely to be intended to be parent names.  For
 724                 // this, we set base_node to None for inner comments since
 725                 // we've already pushed this node onto the resolution stack but
 726                 // for outer comments we explicitly try and resolve against the
 727                 // parent_node first.
 728                 let base_node = if item.is_mod() && item.attrs.inner_docs {
 729                     self.mod_ids.last().copied()
 730                 } else {
 731                     parent_node
 732                 };
 733
 734                 // replace `Self` with suitable item's parent name
 735                 if path_str.starts_with("Self::") {
 736                     if let Some(ref name) = parent_name {
 737                         resolved_self = format!("{}::{}", name, &path_str[6..]);
 738                         path_str = &resolved_self;
 739                     }
 740                 }
 741
 742                 match disambiguator.map(Disambiguator::ns) {
 743                     Some(ns @ (ValueNS | TypeNS)) => {
 744                         match self.resolve(path_str, ns, &current_item, base_node, &extra_fragment)
 745                         {
 746                             Ok(res) => res,
 747                             Err(ErrorKind::ResolutionFailure) => {
 748                                 resolution_failure(cx, &item, path_str, &dox, link_range);
 749                                 // This could just be a normal link or a broken link
 750                                 // we could potentially check if something is
 751                                 // "intra-doc-link-like" and warn in that case.
 752                                 continue;
 753                             }
 754                             Err(ErrorKind::AnchorFailure(msg)) => {
 755                                 anchor_failure(cx, &item, &ori_link, &dox, link_range, msg);
 756                                 continue;
 757                             }
 758                         }
 759                     }
 760                     None => {
 761                         // Try everything!
 762                         let mut candidates = PerNS {
 763                             macro_ns: self
 764                                 .macro_resolve(path_str, base_node)
 765                                 .map(|res| (res, extra_fragment.clone())),
 766                             type_ns: match self.resolve(
 767                                 path_str,
 768                                 TypeNS,
 769                                 &current_item,
 770                                 base_node,
 771                                 &extra_fragment,
 772                             ) {
 773                                 Ok(res) => {
 774                                     debug!("got res in TypeNS: {:?}", res);
 775                                     Some(res)
 776                                 }
 777                                 Err(ErrorKind::AnchorFailure(msg)) => {
 778                                     anchor_failure(cx, &item, &ori_link, &dox, link_range, msg);
 779                                     continue;
 780                                 }
 781                                 Err(ErrorKind::ResolutionFailure) => None,
 782                             },
 783                             value_ns: match self.resolve(
 784                                 path_str,
 785                                 ValueNS,
 786                                 &current_item,
 787                                 base_node,
 788                                 &extra_fragment,
 789                             ) {
 790                                 Ok(res) => Some(res),
 791                                 Err(ErrorKind::AnchorFailure(msg)) => {
 792                                     anchor_failure(cx, &item, &ori_link, &dox, link_range, msg);
 793                                     continue;
 794                                 }
 795                                 Err(ErrorKind::ResolutionFailure) => None,
 796                             }
 797                             .and_then(|(res, fragment)| {
 798                                 // Constructors are picked up in the type namespace.
 799                                 match res {
 800                                     Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) => None,
 801                                     _ => match (fragment, extra_fragment) {
 802                                         (Some(fragment), Some(_)) => {
 803                                             // Shouldn't happen but who knows?
 804                                             Some((res, Some(fragment)))
 805                                         }
 806                                         (fragment, None) | (None, fragment) => {
 807                                             Some((res, fragment))
 808                                         }
 809                                     },
 810                                 }
 811                             }),
 812                         };
 813
 814                         if candidates.is_empty() {
 815                             resolution_failure(cx, &item, path_str, &dox, link_range);
 816                             // this could just be a normal link
 817                             continue;
 818                         }
 819
 820                         let len = candidates.clone().present_items().count();
 821
 822                         if len == 1 {
 823                             candidates.present_items().next().unwrap()
 824                         } else if len == 2 && is_derive_trait_collision(&candidates) {
 825                             candidates.type_ns.unwrap()
 826                         } else {
 827                             if is_derive_trait_collision(&candidates) {
 828                                 candidates.macro_ns = None;
 829                             }
 830                             let candidates =
 831                                 candidates.map(|candidate| candidate.map(|(res, _)| res));
 832                             ambiguity_error(
 833                                 cx,
 834                                 &item,
 835                                 path_str,
 836                                 &dox,
 837                                 link_range,
 838                                 candidates.present_items().collect(),
 839                             );
 840                             continue;
 841                         }
 842                     }
 843                     Some(MacroNS) => {
 844                         if let Some(res) = self.macro_resolve(path_str, base_node) {
 845                             (res, extra_fragment)
 846                         } else {
 847                             resolution_failure(cx, &item, path_str, &dox, link_range);
 848                             continue;
 849                         }
 850                     }
 851                 }
 852             };
 853
 854             // Check for a primitive which might conflict with a module
 855             // Report the ambiguity and require that the user specify which one they meant.
 856             // FIXME: could there ever be a primitive not in the type namespace?
 857             if matches!(
 858                 disambiguator,
 859                 None | Some(Disambiguator::Namespace(Namespace::TypeNS) | Disambiguator::Primitive)
 860             ) && !matches!(res, Res::PrimTy(_))
 861             {
 862                 if let Some((path, prim)) = is_primitive(path_str, TypeNS) {
 863                     // `prim@char`
 864                     if matches!(disambiguator, Some(Disambiguator::Primitive)) {
 865                         if fragment.is_some() {
 866                             anchor_failure(
 867                                 cx,
 868                                 &item,
 869                                 path_str,
 870                                 &dox,
 871                                 link_range,
 872                                 AnchorFailure::Primitive,
 873                             );
 874                             continue;
 875                         }
 876                         res = prim;
 877                         fragment = Some(path.to_owned());
 878                     } else {
 879                         // `[char]` when a `char` module is in scope
 880                         let candidates = vec![res, prim];
 881                         ambiguity_error(cx, &item, path_str, &dox, link_range, candidates);
 882                         continue;
 883                     }
 884                 }
 885             }
 886
 887             let report_mismatch = |specified: Disambiguator, resolved: Disambiguator| {
 888                 // The resolved item did not match the disambiguator; give a better error than 'not found'
 889                 let msg = format!("incompatible link kind for `{}`", path_str);
 890                 report_diagnostic(cx, &msg, &item, &dox, link_range.clone(), |diag, sp| {
 891                     let note = format!(
 892                         "this link resolved to {} {}, which is not {} {}",
 893                         resolved.article(),
 894                         resolved.descr(),
 895                         specified.article(),
 896                         specified.descr()
 897                     );
 898                     diag.note(&note);
 899                     suggest_disambiguator(resolved, diag, path_str, &dox, sp, &link_range);
 900                 });
 901             };
 902             if let Res::PrimTy(_) = res {
 903                 match disambiguator {
 904                     Some(Disambiguator::Primitive | Disambiguator::Namespace(_)) | None => {
 905                         item.attrs.links.push((ori_link, None, fragment))
 906                     }
 907                     Some(other) => {
 908                         report_mismatch(other, Disambiguator::Primitive);
 909                         continue;
 910                     }
 911                 }
 912             } else {
 913                 debug!("intra-doc link to {} resolved to {:?}", path_str, res);
 914
 915                 // Disallow e.g. linking to enums with `struct@`
 916                 if let Res::Def(kind, _) = res {
 917                     debug!("saw kind {:?} with disambiguator {:?}", kind, disambiguator);
 918                     match (self.kind_side_channel.take().unwrap_or(kind), disambiguator) {
 919                         | (DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst, Some(Disambiguator::Kind(DefKind::Const)))
 920                         // NOTE: this allows 'method' to mean both normal functions and associated functions
 921                         // This can't cause ambiguity because both are in the same namespace.
 922                         | (DefKind::Fn | DefKind::AssocFn, Some(Disambiguator::Kind(DefKind::Fn)))
 923                         // These are namespaces; allow anything in the namespace to match
 924                         | (_, Some(Disambiguator::Namespace(_)))
 925                         // If no disambiguator given, allow anything
 926                         | (_, None)
 927                         // All of these are valid, so do nothing
 928                         => {}
 929                         (actual, Some(Disambiguator::Kind(expected))) if actual == expected => {}
 930                         (_, Some(specified @ Disambiguator::Kind(_) | specified @ Disambiguator::Primitive)) => {
 931                             report_mismatch(specified, Disambiguator::Kind(kind));
 932                             continue;
 933                         }
 934                     }
 935                 }
 936
 937                 // item can be non-local e.g. when using #[doc(primitive = "pointer")]
 938                 if let Some((src_id, dst_id)) = res
 939                     .opt_def_id()
 940                     .and_then(|def_id| def_id.as_local())
 941                     .and_then(|dst_id| item.def_id.as_local().map(|src_id| (src_id, dst_id)))
 942                 {
 943                     use rustc_hir::def_id::LOCAL_CRATE;
 944
 945                     let hir_src = self.cx.tcx.hir().local_def_id_to_hir_id(src_id);
 946                     let hir_dst = self.cx.tcx.hir().local_def_id_to_hir_id(dst_id);
 947
 948                     if self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_src)
 949                         && !self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_dst)
 950                     {
 951                         privacy_error(cx, &item, &path_str, &dox, link_range);
 952                         continue;
 953                     }
 954                 }
 955                 let id = register_res(cx, res);
 956                 item.attrs.links.push((ori_link, Some(id), fragment));
 957             }
 958         }
 959
 960         if item.is_mod() && !item.attrs.inner_docs {
 961             self.mod_ids.push(item.def_id);
 962         }
 963
 964         if item.is_mod() {
 965             let ret = self.fold_item_recur(item);
 966
 967             self.mod_ids.pop();
 968
 969             ret
 970         } else {
 971             self.fold_item_recur(item)
 972         }
 973     }
 974
 975     // FIXME: if we can resolve intra-doc links from other crates, we can use the stock
 976     // `fold_crate`, but until then we should avoid scanning `krate.external_traits` since those
 977     // will never resolve properly
 978     fn fold_crate(&mut self, mut c: Crate) -> Crate {
 979         c.module = c.module.take().and_then(|module| self.fold_item(module));
 980
 981         c
 982     }
 983 }
 984
 985 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 986 enum Disambiguator {
 987     Primitive,
 988     Kind(DefKind),
 989     Namespace(Namespace),
 990 }
 991
 992 impl Disambiguator {
 993     /// (disambiguator, path_str)
 994     fn from_str(link: &str) -> Result<(Self, &str), ()> {
 995         use Disambiguator::{Kind, Namespace as NS, Primitive};
 996
 997         let find_suffix = || {
 998             let suffixes = [
 999                 ("!()", DefKind::Macro(MacroKind::Bang)),
1000                 ("()", DefKind::Fn),
1001                 ("!", DefKind::Macro(MacroKind::Bang)),
1002             ];
1003             for &(suffix, kind) in &suffixes {
1004                 if link.ends_with(suffix) {
1005                     return Ok((Kind(kind), link.trim_end_matches(suffix)));
1006                 }
1007             }
1008             Err(())
1009         };
1010
1011         if let Some(idx) = link.find('@') {
1012             let (prefix, rest) = link.split_at(idx);
1013             let d = match prefix {
1014                 "struct" => Kind(DefKind::Struct),
1015                 "enum" => Kind(DefKind::Enum),
1016                 "trait" => Kind(DefKind::Trait),
1017                 "union" => Kind(DefKind::Union),
1018                 "module" | "mod" => Kind(DefKind::Mod),
1019                 "const" | "constant" => Kind(DefKind::Const),
1020                 "static" => Kind(DefKind::Static),
1021                 "function" | "fn" | "method" => Kind(DefKind::Fn),
1022                 "derive" => Kind(DefKind::Macro(MacroKind::Derive)),
1023                 "type" => NS(Namespace::TypeNS),
1024                 "value" => NS(Namespace::ValueNS),
1025                 "macro" => NS(Namespace::MacroNS),
1026                 "prim" | "primitive" => Primitive,
1027                 _ => return find_suffix(),
1028             };
1029             Ok((d, &rest[1..]))
1030         } else {
1031             find_suffix()
1032         }
1033     }
1034
1035     /// WARNING: panics on `Res::Err`
1036     fn from_res(res: Res) -> Self {
1037         match res {
1038             Res::Def(kind, _) => Disambiguator::Kind(kind),
1039             Res::PrimTy(_) => Disambiguator::Primitive,
1040             _ => Disambiguator::Namespace(res.ns().expect("can't call `from_res` on Res::err")),
1041         }
1042     }
1043
1044     /// Return (description of the change, suggestion)
1045     fn display_for(self, path_str: &str) -> (&'static str, String) {
1046         const PREFIX: &str = "prefix with the item kind";
1047         const FUNCTION: &str = "add parentheses";
1048         const MACRO: &str = "add an exclamation mark";
1049
1050         let kind = match self {
1051             Disambiguator::Primitive => return (PREFIX, format!("prim@{}", path_str)),
1052             Disambiguator::Kind(kind) => kind,
1053             Disambiguator::Namespace(_) => panic!("display_for cannot be used on namespaces"),
1054         };
1055         if kind == DefKind::Macro(MacroKind::Bang) {
1056             return (MACRO, format!("{}!", path_str));
1057         } else if kind == DefKind::Fn || kind == DefKind::AssocFn {
1058             return (FUNCTION, format!("{}()", path_str));
1059         }
1060
1061         let prefix = match kind {
1062             DefKind::Struct => "struct",
1063             DefKind::Enum => "enum",
1064             DefKind::Trait => "trait",
1065             DefKind::Union => "union",
1066             DefKind::Mod => "mod",
1067             DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst => {
1068                 "const"
1069             }
1070             DefKind::Static => "static",
1071             DefKind::Macro(MacroKind::Derive) => "derive",
1072             // Now handle things that don't have a specific disambiguator
1073             _ => match kind
1074                 .ns()
1075                 .expect("tried to calculate a disambiguator for a def without a namespace?")
1076             {
1077                 Namespace::TypeNS => "type",
1078                 Namespace::ValueNS => "value",
1079                 Namespace::MacroNS => "macro",
1080             },
1081         };
1082
1083         // FIXME: if this is an implied shortcut link, it's bad style to suggest `@`
1084         (PREFIX, format!("{}@{}", prefix, path_str))
1085     }
1086
1087     fn ns(self) -> Namespace {
1088         match self {
1089             Self::Namespace(n) => n,
1090             Self::Kind(k) => {
1091                 k.ns().expect("only DefKinds with a valid namespace can be disambiguators")
1092             }
1093             Self::Primitive => TypeNS,
1094         }
1095     }
1096
1097     fn article(self) -> &'static str {
1098         match self {
1099             Self::Namespace(_) => panic!("article() doesn't make sense for namespaces"),
1100             Self::Kind(k) => k.article(),
1101             Self::Primitive => "a",
1102         }
1103     }
1104
1105     fn descr(self) -> &'static str {
1106         match self {
1107             Self::Namespace(n) => n.descr(),
1108             // HACK(jynelson): by looking at the source I saw the DefId we pass
1109             // for `expected.descr()` doesn't matter, since it's not a crate
1110             Self::Kind(k) => k.descr(DefId::local(hir::def_id::DefIndex::from_usize(0))),
1111             Self::Primitive => "builtin type",
1112         }
1113     }
1114 }
1115
1116 /// Reports a diagnostic for an intra-doc link.
1117 ///
1118 /// If no link range is provided, or the source span of the link cannot be determined, the span of
1119 /// the entire documentation block is used for the lint. If a range is provided but the span
1120 /// calculation fails, a note is added to the diagnostic pointing to the link in the markdown.
1121 ///
1122 /// The `decorate` callback is invoked in all cases to allow further customization of the
1123 /// diagnostic before emission. If the span of the link was able to be determined, the second
1124 /// parameter of the callback will contain it, and the primary span of the diagnostic will be set
1125 /// to it.
1126 fn report_diagnostic(
1127     cx: &DocContext<'_>,
1128     msg: &str,
1129     item: &Item,
1130     dox: &str,
1131     link_range: Option<Range<usize>>,
1132     decorate: impl FnOnce(&mut DiagnosticBuilder<'_>, Option<rustc_span::Span>),
1133 ) {
1134     let hir_id = match cx.as_local_hir_id(item.def_id) {
1135         Some(hir_id) => hir_id,
1136         None => {
1137             // If non-local, no need to check anything.
1138             info!("ignoring warning from parent crate: {}", msg);
1139             return;
1140         }
1141     };
1142
1143     let attrs = &item.attrs;
1144     let sp = span_of_attrs(attrs).unwrap_or(item.source.span());
1145
1146     cx.tcx.struct_span_lint_hir(lint::builtin::BROKEN_INTRA_DOC_LINKS, hir_id, sp, |lint| {
1147         let mut diag = lint.build(msg);
1148
1149         let span = link_range
1150             .as_ref()
1151             .and_then(|range| super::source_span_for_markdown_range(cx, dox, range, attrs));
1152
1153         if let Some(link_range) = link_range {
1154             if let Some(sp) = span {
1155                 diag.set_span(sp);
1156             } else {
1157                 // blah blah blah\nblah\nblah [blah] blah blah\nblah blah
1158                 //                       ^     ~~~~
1159                 //                       |     link_range
1160                 //                       last_new_line_offset
1161                 let last_new_line_offset = dox[..link_range.start].rfind('\n').map_or(0, |n| n + 1);
1162                 let line = dox[last_new_line_offset..].lines().next().unwrap_or("");
1163
1164                 // Print the line containing the `link_range` and manually mark it with '^'s.
1165                 diag.note(&format!(
1166                     "the link appears in this line:\n\n{line}\n\
1167                          {indicator: <before$}{indicator:^<found$}",
1168                     line = line,
1169                     indicator = "",
1170                     before = link_range.start - last_new_line_offset,
1171                     found = link_range.len(),
1172                 ));
1173             }
1174         }
1175
1176         decorate(&mut diag, span);
1177
1178         diag.emit();
1179     });
1180 }
1181
1182 fn resolution_failure(
1183     cx: &DocContext<'_>,
1184     item: &Item,
1185     path_str: &str,
1186     dox: &str,
1187     link_range: Option<Range<usize>>,
1188 ) {
1189     report_diagnostic(
1190         cx,
1191         &format!("unresolved link to `{}`", path_str),
1192         item,
1193         dox,
1194         link_range,
1195         |diag, sp| {
1196             if let Some(sp) = sp {
1197                 diag.span_label(sp, "unresolved link");
1198             }
1199
1200             diag.help(r#"to escape `[` and `]` characters, add '\' before them like `\[` or `\]`"#);
1201         },
1202     );
1203 }
1204
1205 fn anchor_failure(
1206     cx: &DocContext<'_>,
1207     item: &Item,
1208     path_str: &str,
1209     dox: &str,
1210     link_range: Option<Range<usize>>,
1211     failure: AnchorFailure,
1212 ) {
1213     let msg = match failure {
1214         AnchorFailure::MultipleAnchors => format!("`{}` contains multiple anchors", path_str),
1215         AnchorFailure::Primitive
1216         | AnchorFailure::Variant
1217         | AnchorFailure::AssocConstant
1218         | AnchorFailure::AssocType
1219         | AnchorFailure::Field
1220         | AnchorFailure::Method => {
1221             let kind = match failure {
1222                 AnchorFailure::Primitive => "primitive type",
1223                 AnchorFailure::Variant => "enum variant",
1224                 AnchorFailure::AssocConstant => "associated constant",
1225                 AnchorFailure::AssocType => "associated type",
1226                 AnchorFailure::Field => "struct field",
1227                 AnchorFailure::Method => "method",
1228                 AnchorFailure::MultipleAnchors => unreachable!("should be handled already"),
1229             };
1230
1231             format!(
1232                 "`{}` contains an anchor, but links to {kind}s are already anchored",
1233                 path_str,
1234                 kind = kind
1235             )
1236         }
1237     };
1238
1239     report_diagnostic(cx, &msg, item, dox, link_range, |diag, sp| {
1240         if let Some(sp) = sp {
1241             diag.span_label(sp, "contains invalid anchor");
1242         }
1243     });
1244 }
1245
1246 fn ambiguity_error(
1247     cx: &DocContext<'_>,
1248     item: &Item,
1249     path_str: &str,
1250     dox: &str,
1251     link_range: Option<Range<usize>>,
1252     candidates: Vec<Res>,
1253 ) {
1254     let mut msg = format!("`{}` is ", path_str);
1255
1256     match candidates.as_slice() {
1257         [first_def, second_def] => {
1258             msg += &format!(
1259                 "both {} {} and {} {}",
1260                 first_def.article(),
1261                 first_def.descr(),
1262                 second_def.article(),
1263                 second_def.descr(),
1264             );
1265         }
1266         _ => {
1267             let mut candidates = candidates.iter().peekable();
1268             while let Some(res) = candidates.next() {
1269                 if candidates.peek().is_some() {
1270                     msg += &format!("{} {}, ", res.article(), res.descr());
1271                 } else {
1272                     msg += &format!("and {} {}", res.article(), res.descr());
1273                 }
1274             }
1275         }
1276     }
1277
1278     report_diagnostic(cx, &msg, item, dox, link_range.clone(), |diag, sp| {
1279         if let Some(sp) = sp {
1280             diag.span_label(sp, "ambiguous link");
1281         } else {
1282             diag.note("ambiguous link");
1283         }
1284
1285         for res in candidates {
1286             let disambiguator = Disambiguator::from_res(res);
1287             suggest_disambiguator(disambiguator, diag, path_str, dox, sp, &link_range);
1288         }
1289     });
1290 }
1291
1292 fn suggest_disambiguator(
1293     disambiguator: Disambiguator,
1294     diag: &mut DiagnosticBuilder<'_>,
1295     path_str: &str,
1296     dox: &str,
1297     sp: Option<rustc_span::Span>,
1298     link_range: &Option<Range<usize>>,
1299 ) {
1300     let (action, mut suggestion) = disambiguator.display_for(path_str);
1301     let help = format!("to link to the {}, {}", disambiguator.descr(), action);
1302
1303     if let Some(sp) = sp {
1304         let link_range = link_range.as_ref().expect("must have a link range if we have a span");
1305         if dox.bytes().nth(link_range.start) == Some(b'`') {
1306             suggestion = format!("`{}`", suggestion);
1307         }
1308
1309         diag.span_suggestion(sp, &help, suggestion, Applicability::MaybeIncorrect);
1310     } else {
1311         diag.help(&format!("{}: {}", help, suggestion));
1312     }
1313 }
1314
1315 fn privacy_error(
1316     cx: &DocContext<'_>,
1317     item: &Item,
1318     path_str: &str,
1319     dox: &str,
1320     link_range: Option<Range<usize>>,
1321 ) {
1322     let item_name = item.name.as_deref().unwrap_or("<unknown>");
1323     let msg =
1324         format!("public documentation for `{}` links to private item `{}`", item_name, path_str);
1325
1326     report_diagnostic(cx, &msg, item, dox, link_range, |diag, sp| {
1327         if let Some(sp) = sp {
1328             diag.span_label(sp, "this item is private");
1329         }
1330
1331         let note_msg = if cx.render_options.document_private {
1332             "this link resolves only because you passed `--document-private-items`, but will break without"
1333         } else {
1334             "this link will resolve properly if you pass `--document-private-items`"
1335         };
1336         diag.note(note_msg);
1337     });
1338 }
1339
1340 /// Given an enum variant's res, return the res of its enum and the associated fragment.
1341 fn handle_variant(
1342     cx: &DocContext<'_>,
1343     res: Res,
1344     extra_fragment: &Option<String>,
1345 ) -> Result<(Res, Option<String>), ErrorKind> {
1346     use rustc_middle::ty::DefIdTree;
1347
1348     if extra_fragment.is_some() {
1349         return Err(ErrorKind::AnchorFailure(AnchorFailure::Variant));
1350     }
1351     let parent = if let Some(parent) = cx.tcx.parent(res.def_id()) {
1352         parent
1353     } else {
1354         return Err(ErrorKind::ResolutionFailure);
1355     };
1356     let parent_def = Res::Def(DefKind::Enum, parent);
1357     let variant = cx.tcx.expect_variant_res(res);
1358     Ok((parent_def, Some(format!("variant.{}", variant.ident.name))))
1359 }
1360
1361 const PRIMITIVES: &[(&str, Res)] = &[
1362     ("u8", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U8))),
1363     ("u16", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U16))),
1364     ("u32", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U32))),
1365     ("u64", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U64))),
1366     ("u128", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U128))),
1367     ("usize", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::Usize))),
1368     ("i8", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I8))),
1369     ("i16", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I16))),
1370     ("i32", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I32))),
1371     ("i64", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I64))),
1372     ("i128", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I128))),
1373     ("isize", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::Isize))),
1374     ("f32", Res::PrimTy(hir::PrimTy::Float(rustc_ast::FloatTy::F32))),
1375     ("f64", Res::PrimTy(hir::PrimTy::Float(rustc_ast::FloatTy::F64))),
1376     ("str", Res::PrimTy(hir::PrimTy::Str)),
1377     ("bool", Res::PrimTy(hir::PrimTy::Bool)),
1378     ("true", Res::PrimTy(hir::PrimTy::Bool)),
1379     ("false", Res::PrimTy(hir::PrimTy::Bool)),
1380     ("char", Res::PrimTy(hir::PrimTy::Char)),
1381 ];
1382
1383 fn is_primitive(path_str: &str, ns: Namespace) -> Option<(&'static str, Res)> {
1384     if ns == TypeNS {
1385         PRIMITIVES
1386             .iter()
1387             .filter(|x| x.0 == path_str)
1388             .copied()
1389             .map(|x| if x.0 == "true" || x.0 == "false" { ("bool", x.1) } else { x })
1390             .next()
1391     } else {
1392         None
1393     }
1394 }
1395
1396 fn primitive_impl(cx: &DocContext<'_>, path_str: &str) -> Option<&'static SmallVec<[DefId; 4]>> {
1397     Some(PrimitiveType::from_symbol(Symbol::intern(path_str))?.impls(cx.tcx))
1398 }