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                 debug!("resolving {} as a macro in the module {:?}", path_str, module_id);
 165                 if let Ok((_, res)) =
 166                     resolver.resolve_str_path_error(DUMMY_SP, path_str, MacroNS, module_id)
 167                 {
 168                     // don't resolve builtins like `#[derive]`
 169                     if let Res::Def(..) = res {
 170                         let res = res.map_id(|_| panic!("unexpected node_id"));
 171                         return Some(res);
 172                     }
 173                 }
 174             } else {
 175                 debug!("attempting to resolve item without parent module: {}", path_str);
 176             }
 177             None
 178         })
 179     }
 180     /// Resolves a string as a path within a particular namespace. Also returns an optional
 181     /// URL fragment in the case of variants and methods.
 182     fn resolve(
 183         &self,
 184         path_str: &str,
 185         ns: Namespace,
 186         current_item: &Option<String>,
 187         parent_id: Option<DefId>,
 188         extra_fragment: &Option<String>,
 189     ) -> Result<(Res, Option<String>), ErrorKind> {
 190         let cx = self.cx;
 191
 192         // In case we're in a module, try to resolve the relative path.
 193         if let Some(module_id) = parent_id {
 194             let result = cx.enter_resolver(|resolver| {
 195                 resolver.resolve_str_path_error(DUMMY_SP, &path_str, ns, module_id)
 196             });
 197             debug!("{} resolved to {:?} in namespace {:?}", path_str, result, ns);
 198             let result = match result {
 199                 Ok((_, Res::Err)) => Err(ErrorKind::ResolutionFailure),
 200                 _ => result.map_err(|_| ErrorKind::ResolutionFailure),
 201             };
 202
 203             if let Ok((_, res)) = result {
 204                 let res = res.map_id(|_| panic!("unexpected node_id"));
 205                 // In case this is a trait item, skip the
 206                 // early return and try looking for the trait.
 207                 let value = match res {
 208                     Res::Def(DefKind::AssocFn | DefKind::AssocConst, _) => true,
 209                     Res::Def(DefKind::AssocTy, _) => false,
 210                     Res::Def(DefKind::Variant, _) => {
 211                         return handle_variant(cx, res, extra_fragment);
 212                     }
 213                     // Not a trait item; just return what we found.
 214                     Res::PrimTy(..) => {
 215                         if extra_fragment.is_some() {
 216                             return Err(ErrorKind::AnchorFailure(AnchorFailure::Primitive));
 217                         }
 218                         return Ok((res, Some(path_str.to_owned())));
 219                     }
 220                     Res::Def(DefKind::Mod, _) => {
 221                         return Ok((res, extra_fragment.clone()));
 222                     }
 223                     _ => {
 224                         return Ok((res, extra_fragment.clone()));
 225                     }
 226                 };
 227
 228                 if value != (ns == ValueNS) {
 229                     return Err(ErrorKind::ResolutionFailure);
 230                 }
 231             } else if let Some((path, prim)) = is_primitive(path_str, ns) {
 232                 if extra_fragment.is_some() {
 233                     return Err(ErrorKind::AnchorFailure(AnchorFailure::Primitive));
 234                 }
 235                 return Ok((prim, Some(path.to_owned())));
 236             }
 237
 238             // Try looking for methods and associated items.
 239             let mut split = path_str.rsplitn(2, "::");
 240             let item_name =
 241                 split.next().map(|f| Symbol::intern(f)).ok_or(ErrorKind::ResolutionFailure)?;
 242             let path = split
 243                 .next()
 244                 .map(|f| {
 245                     if f == "self" || f == "Self" {
 246                         if let Some(name) = current_item.as_ref() {
 247                             return name.clone();
 248                         }
 249                     }
 250                     f.to_owned()
 251                 })
 252                 .ok_or(ErrorKind::ResolutionFailure)?;
 253
 254             if let Some((path, prim)) = is_primitive(&path, TypeNS) {
 255                 for &impl_ in primitive_impl(cx, &path).ok_or(ErrorKind::ResolutionFailure)? {
 256                     let link = cx
 257                         .tcx
 258                         .associated_items(impl_)
 259                         .find_by_name_and_namespace(
 260                             cx.tcx,
 261                             Ident::with_dummy_span(item_name),
 262                             ns,
 263                             impl_,
 264                         )
 265                         .map(|item| match item.kind {
 266                             ty::AssocKind::Fn => "method",
 267                             ty::AssocKind::Const => "associatedconstant",
 268                             ty::AssocKind::Type => "associatedtype",
 269                         })
 270                         .map(|out| (prim, Some(format!("{}#{}.{}", path, out, item_name))));
 271                     if let Some(link) = link {
 272                         return Ok(link);
 273                     }
 274                 }
 275                 return Err(ErrorKind::ResolutionFailure);
 276             }
 277
 278             let (_, ty_res) = cx
 279                 .enter_resolver(|resolver| {
 280                     resolver.resolve_str_path_error(DUMMY_SP, &path, TypeNS, module_id)
 281                 })
 282                 .map_err(|_| ErrorKind::ResolutionFailure)?;
 283             if let Res::Err = ty_res {
 284                 return if ns == Namespace::ValueNS {
 285                     self.variant_field(path_str, current_item, module_id)
 286                 } else {
 287                     Err(ErrorKind::ResolutionFailure)
 288                 };
 289             }
 290             let ty_res = ty_res.map_id(|_| panic!("unexpected node_id"));
 291             let res = match ty_res {
 292                 Res::Def(
 293                     DefKind::Struct | DefKind::Union | DefKind::Enum | DefKind::TyAlias,
 294                     did,
 295                 ) => {
 296                     debug!("looking for associated item named {} for item {:?}", item_name, did);
 297                     // Checks if item_name belongs to `impl SomeItem`
 298                     let kind = cx
 299                         .tcx
 300                         .inherent_impls(did)
 301                         .iter()
 302                         .flat_map(|&imp| {
 303                             cx.tcx.associated_items(imp).find_by_name_and_namespace(
 304                                 cx.tcx,
 305                                 Ident::with_dummy_span(item_name),
 306                                 ns,
 307                                 imp,
 308                             )
 309                         })
 310                         .map(|item| item.kind)
 311                         // There should only ever be one associated item that matches from any inherent impl
 312                         .next()
 313                         // Check if item_name belongs to `impl SomeTrait for SomeItem`
 314                         // This gives precedence to `impl SomeItem`:
 315                         // Although having both would be ambiguous, use impl version for compat. sake.
 316                         // To handle that properly resolve() would have to support
 317                         // something like [`ambi_fn`](<SomeStruct as SomeTrait>::ambi_fn)
 318                         .or_else(|| {
 319                             let kind = resolve_associated_trait_item(
 320                                 did, module_id, item_name, ns, &self.cx,
 321                             );
 322                             debug!("got associated item kind {:?}", kind);
 323                             kind
 324                         });
 325
 326                     if let Some(kind) = kind {
 327                         let out = match kind {
 328                             ty::AssocKind::Fn => "method",
 329                             ty::AssocKind::Const => "associatedconstant",
 330                             ty::AssocKind::Type => "associatedtype",
 331                         };
 332                         Some(if extra_fragment.is_some() {
 333                             Err(ErrorKind::AnchorFailure(if kind == ty::AssocKind::Fn {
 334                                 AnchorFailure::Method
 335                             } else {
 336                                 AnchorFailure::AssocConstant
 337                             }))
 338                         } else {
 339                             // HACK(jynelson): `clean` expects the type, not the associated item.
 340                             // but the disambiguator logic expects the associated item.
 341                             // Store the kind in a side channel so that only the disambiguator logic looks at it.
 342                             self.kind_side_channel.set(Some(kind.as_def_kind()));
 343                             Ok((ty_res, Some(format!("{}.{}", out, item_name))))
 344                         })
 345                     } else if ns == Namespace::ValueNS {
 346                         match cx.tcx.type_of(did).kind {
 347                             ty::Adt(def, _) => {
 348                                 let field = if def.is_enum() {
 349                                     def.all_fields().find(|item| item.ident.name == item_name)
 350                                 } else {
 351                                     def.non_enum_variant()
 352                                         .fields
 353                                         .iter()
 354                                         .find(|item| item.ident.name == item_name)
 355                                 };
 356                                 field.map(|item| {
 357                                     if extra_fragment.is_some() {
 358                                         Err(ErrorKind::AnchorFailure(if def.is_enum() {
 359                                             AnchorFailure::Variant
 360                                         } else {
 361                                             AnchorFailure::Field
 362                                         }))
 363                                     } else {
 364                                         Ok((
 365                                             ty_res,
 366                                             Some(format!(
 367                                                 "{}.{}",
 368                                                 if def.is_enum() {
 369                                                     "variant"
 370                                                 } else {
 371                                                     "structfield"
 372                                                 },
 373                                                 item.ident
 374                                             )),
 375                                         ))
 376                                     }
 377                                 })
 378                             }
 379                             _ => None,
 380                         }
 381                     } else {
 382                         // We already know this isn't in ValueNS, so no need to check variant_field
 383                         return Err(ErrorKind::ResolutionFailure);
 384                     }
 385                 }
 386                 Res::Def(DefKind::Trait, did) => cx
 387                     .tcx
 388                     .associated_items(did)
 389                     .find_by_name_and_namespace(cx.tcx, Ident::with_dummy_span(item_name), ns, did)
 390                     .map(|item| {
 391                         let kind = match item.kind {
 392                             ty::AssocKind::Const => "associatedconstant",
 393                             ty::AssocKind::Type => "associatedtype",
 394                             ty::AssocKind::Fn => {
 395                                 if item.defaultness.has_value() {
 396                                     "method"
 397                                 } else {
 398                                     "tymethod"
 399                                 }
 400                             }
 401                         };
 402
 403                         if extra_fragment.is_some() {
 404                             Err(ErrorKind::AnchorFailure(if item.kind == ty::AssocKind::Const {
 405                                 AnchorFailure::AssocConstant
 406                             } else if item.kind == ty::AssocKind::Type {
 407                                 AnchorFailure::AssocType
 408                             } else {
 409                                 AnchorFailure::Method
 410                             }))
 411                         } else {
 412                             let res = Res::Def(item.kind.as_def_kind(), item.def_id);
 413                             Ok((res, Some(format!("{}.{}", kind, item_name))))
 414                         }
 415                     }),
 416                 _ => None,
 417             };
 418             res.unwrap_or_else(|| {
 419                 if ns == Namespace::ValueNS {
 420                     self.variant_field(path_str, current_item, module_id)
 421                 } else {
 422                     Err(ErrorKind::ResolutionFailure)
 423                 }
 424             })
 425         } else {
 426             debug!("attempting to resolve item without parent module: {}", path_str);
 427             Err(ErrorKind::ResolutionFailure)
 428         }
 429     }
 430 }
 431
 432 fn resolve_associated_trait_item(
 433     did: DefId,
 434     module: DefId,
 435     item_name: Symbol,
 436     ns: Namespace,
 437     cx: &DocContext<'_>,
 438 ) -> Option<ty::AssocKind> {
 439     let ty = cx.tcx.type_of(did);
 440     // First consider automatic impls: `impl From<T> for T`
 441     let implicit_impls = crate::clean::get_auto_trait_and_blanket_impls(cx, ty, did);
 442     let mut candidates: Vec<_> = implicit_impls
 443         .flat_map(|impl_outer| {
 444             match impl_outer.inner {
 445                 ImplItem(impl_) => {
 446                     debug!("considering auto or blanket impl for trait {:?}", impl_.trait_);
 447                     // Give precedence to methods that were overridden
 448                     if !impl_.provided_trait_methods.contains(&*item_name.as_str()) {
 449                         let mut items = impl_.items.into_iter().filter_map(|assoc| {
 450                             if assoc.name.as_deref() != Some(&*item_name.as_str()) {
 451                                 return None;
 452                             }
 453                             let kind = assoc
 454                                 .inner
 455                                 .as_assoc_kind()
 456                                 .expect("inner items for a trait should be associated items");
 457                             if kind.namespace() != ns {
 458                                 return None;
 459                             }
 460
 461                             trace!("considering associated item {:?}", assoc.inner);
 462                             // We have a slight issue: normal methods come from `clean` types,
 463                             // but provided methods come directly from `tcx`.
 464                             // Fortunately, we don't need the whole method, we just need to know
 465                             // what kind of associated item it is.
 466                             Some((assoc.def_id, kind))
 467                         });
 468                         let assoc = items.next();
 469                         debug_assert_eq!(items.count(), 0);
 470                         assoc
 471                     } else {
 472                         // These are provided methods or default types:
 473                         // ```
 474                         // trait T {
 475                         //   type A = usize;
 476                         //   fn has_default() -> A { 0 }
 477                         // }
 478                         // ```
 479                         let trait_ = impl_.trait_.unwrap().def_id().unwrap();
 480                         cx.tcx
 481                             .associated_items(trait_)
 482                             .find_by_name_and_namespace(
 483                                 cx.tcx,
 484                                 Ident::with_dummy_span(item_name),
 485                                 ns,
 486                                 trait_,
 487                             )
 488                             .map(|assoc| (assoc.def_id, assoc.kind))
 489                     }
 490                 }
 491                 _ => panic!("get_impls returned something that wasn't an impl"),
 492             }
 493         })
 494         .collect();
 495
 496     // Next consider explicit impls: `impl MyTrait for MyType`
 497     // Give precedence to inherent impls.
 498     if candidates.is_empty() {
 499         let traits = traits_implemented_by(cx, did, module);
 500         debug!("considering traits {:?}", traits);
 501         candidates.extend(traits.iter().filter_map(|&trait_| {
 502             cx.tcx
 503                 .associated_items(trait_)
 504                 .find_by_name_and_namespace(cx.tcx, Ident::with_dummy_span(item_name), ns, trait_)
 505                 .map(|assoc| (assoc.def_id, assoc.kind))
 506         }));
 507     }
 508     // FIXME: warn about ambiguity
 509     debug!("the candidates were {:?}", candidates);
 510     candidates.pop().map(|(_, kind)| kind)
 511 }
 512
 513 /// Given a type, return all traits in scope in `module` implemented by that type.
 514 ///
 515 /// NOTE: this cannot be a query because more traits could be available when more crates are compiled!
 516 /// So it is not stable to serialize cross-crate.
 517 fn traits_implemented_by(cx: &DocContext<'_>, type_: DefId, module: DefId) -> FxHashSet<DefId> {
 518     let mut cache = cx.module_trait_cache.borrow_mut();
 519     let in_scope_traits = cache.entry(module).or_insert_with(|| {
 520         cx.enter_resolver(|resolver| {
 521             resolver.traits_in_scope(module).into_iter().map(|candidate| candidate.def_id).collect()
 522         })
 523     });
 524
 525     let ty = cx.tcx.type_of(type_);
 526     let iter = in_scope_traits.iter().flat_map(|&trait_| {
 527         trace!("considering explicit impl for trait {:?}", trait_);
 528         let mut saw_impl = false;
 529         // Look at each trait implementation to see if it's an impl for `did`
 530         cx.tcx.for_each_relevant_impl(trait_, ty, |impl_| {
 531             // FIXME: this is inefficient, find a way to short-circuit for_each_* so this doesn't take as long
 532             if saw_impl {
 533                 return;
 534             }
 535
 536             let trait_ref = cx.tcx.impl_trait_ref(impl_).expect("this is not an inherent impl");
 537             // Check if these are the same type.
 538             let impl_type = trait_ref.self_ty();
 539             debug!(
 540                 "comparing type {} with kind {:?} against type {:?}",
 541                 impl_type, impl_type.kind, type_
 542             );
 543             // Fast path: if this is a primitive simple `==` will work
 544             saw_impl = impl_type == ty
 545                 || match impl_type.kind {
 546                     // Check if these are the same def_id
 547                     ty::Adt(def, _) => {
 548                         debug!("adt def_id: {:?}", def.did);
 549                         def.did == type_
 550                     }
 551                     ty::Foreign(def_id) => def_id == type_,
 552                     _ => false,
 553                 };
 554         });
 555         if saw_impl { Some(trait_) } else { None }
 556     });
 557     iter.collect()
 558 }
 559
 560 /// Check for resolve collisions between a trait and its derive
 561 ///
 562 /// These are common and we should just resolve to the trait in that case
 563 fn is_derive_trait_collision<T>(ns: &PerNS<Option<(Res, T)>>) -> bool {
 564     if let PerNS {
 565         type_ns: Some((Res::Def(DefKind::Trait, _), _)),
 566         macro_ns: Some((Res::Def(DefKind::Macro(MacroKind::Derive), _), _)),
 567         ..
 568     } = *ns
 569     {
 570         true
 571     } else {
 572         false
 573     }
 574 }
 575
 576 impl<'a, 'tcx> DocFolder for LinkCollector<'a, 'tcx> {
 577     fn fold_item(&mut self, mut item: Item) -> Option<Item> {
 578         use rustc_middle::ty::DefIdTree;
 579
 580         let parent_node = if item.is_fake() {
 581             // FIXME: is this correct?
 582             None
 583         } else {
 584             let mut current = item.def_id;
 585             // The immediate parent might not always be a module.
 586             // Find the first parent which is.
 587             loop {
 588                 if let Some(parent) = self.cx.tcx.parent(current) {
 589                     if self.cx.tcx.def_kind(parent) == DefKind::Mod {
 590                         break Some(parent);
 591                     }
 592                     current = parent;
 593                 } else {
 594                     break None;
 595                 }
 596             }
 597         };
 598
 599         if parent_node.is_some() {
 600             trace!("got parent node for {:?} {:?}, id {:?}", item.type_(), item.name, item.def_id);
 601         }
 602
 603         let current_item = match item.inner {
 604             ModuleItem(..) => {
 605                 if item.attrs.inner_docs {
 606                     if item.def_id.is_top_level_module() { item.name.clone() } else { None }
 607                 } else {
 608                     match parent_node.or(self.mod_ids.last().copied()) {
 609                         Some(parent) if !parent.is_top_level_module() => {
 610                             // FIXME: can we pull the parent module's name from elsewhere?
 611                             Some(self.cx.tcx.item_name(parent).to_string())
 612                         }
 613                         _ => None,
 614                     }
 615                 }
 616             }
 617             ImplItem(Impl { ref for_, .. }) => {
 618                 for_.def_id().map(|did| self.cx.tcx.item_name(did).to_string())
 619             }
 620             // we don't display docs on `extern crate` items anyway, so don't process them.
 621             ExternCrateItem(..) => {
 622                 debug!("ignoring extern crate item {:?}", item.def_id);
 623                 return self.fold_item_recur(item);
 624             }
 625             ImportItem(Import::Simple(ref name, ..)) => Some(name.clone()),
 626             MacroItem(..) => None,
 627             _ => item.name.clone(),
 628         };
 629
 630         if item.is_mod() && item.attrs.inner_docs {
 631             self.mod_ids.push(item.def_id);
 632         }
 633
 634         let cx = self.cx;
 635         let dox = item.attrs.collapsed_doc_value().unwrap_or_else(String::new);
 636         trace!("got documentation '{}'", dox);
 637
 638         // find item's parent to resolve `Self` in item's docs below
 639         let parent_name = self.cx.as_local_hir_id(item.def_id).and_then(|item_hir| {
 640             let parent_hir = self.cx.tcx.hir().get_parent_item(item_hir);
 641             let item_parent = self.cx.tcx.hir().find(parent_hir);
 642             match item_parent {
 643                 Some(hir::Node::Item(hir::Item {
 644                     kind:
 645                         hir::ItemKind::Impl {
 646                             self_ty:
 647                                 hir::Ty {
 648                                     kind:
 649                                         hir::TyKind::Path(hir::QPath::Resolved(
 650                                             _,
 651                                             hir::Path { segments, .. },
 652                                         )),
 653                                     ..
 654                                 },
 655                             ..
 656                         },
 657                     ..
 658                 })) => segments.first().map(|seg| seg.ident.to_string()),
 659                 Some(hir::Node::Item(hir::Item {
 660                     ident, kind: hir::ItemKind::Enum(..), ..
 661                 }))
 662                 | Some(hir::Node::Item(hir::Item {
 663                     ident, kind: hir::ItemKind::Struct(..), ..
 664                 }))
 665                 | Some(hir::Node::Item(hir::Item {
 666                     ident, kind: hir::ItemKind::Union(..), ..
 667                 }))
 668                 | Some(hir::Node::Item(hir::Item {
 669                     ident, kind: hir::ItemKind::Trait(..), ..
 670                 })) => Some(ident.to_string()),
 671                 _ => None,
 672             }
 673         });
 674
 675         for (ori_link, link_range) in markdown_links(&dox) {
 676             trace!("considering link '{}'", ori_link);
 677
 678             // Bail early for real links.
 679             if ori_link.contains('/') {
 680                 continue;
 681             }
 682
 683             // [] is mostly likely not supposed to be a link
 684             if ori_link.is_empty() {
 685                 continue;
 686             }
 687
 688             //let had_backticks = ori_link.contains("`");
 689             let link = ori_link.replace("`", "");
 690             let parts = link.split('#').collect::<Vec<_>>();
 691             let (link, extra_fragment) = if parts.len() > 2 {
 692                 anchor_failure(cx, &item, &link, &dox, link_range, AnchorFailure::MultipleAnchors);
 693                 continue;
 694             } else if parts.len() == 2 {
 695                 if parts[0].trim().is_empty() {
 696                     // This is an anchor to an element of the current page, nothing to do in here!
 697                     continue;
 698                 }
 699                 (parts[0], Some(parts[1].to_owned()))
 700             } else {
 701                 (parts[0], None)
 702             };
 703             let resolved_self;
 704             let link_text;
 705             let mut path_str;
 706             let disambiguator;
 707             let (mut res, mut fragment) = {
 708                 path_str = if let Ok((d, path)) = Disambiguator::from_str(&link) {
 709                     disambiguator = Some(d);
 710                     path
 711                 } else {
 712                     disambiguator = None;
 713                     &link
 714                 }
 715                 .trim();
 716
 717                 if path_str.contains(|ch: char| !(ch.is_alphanumeric() || ch == ':' || ch == '_')) {
 718                     continue;
 719                 }
 720
 721                 // We stripped ` characters for `path_str`.
 722                 // The original link might have had multiple pairs of backticks,
 723                 // but we don't handle this case.
 724                 //link_text = if had_backticks { format!("`{}`", path_str) } else { path_str.to_owned() };
 725                 link_text = path_str.to_owned();
 726
 727                 // In order to correctly resolve intra-doc-links we need to
 728                 // pick a base AST node to work from.  If the documentation for
 729                 // this module came from an inner comment (//!) then we anchor
 730                 // our name resolution *inside* the module.  If, on the other
 731                 // hand it was an outer comment (///) then we anchor the name
 732                 // resolution in the parent module on the basis that the names
 733                 // used are more likely to be intended to be parent names.  For
 734                 // this, we set base_node to None for inner comments since
 735                 // we've already pushed this node onto the resolution stack but
 736                 // for outer comments we explicitly try and resolve against the
 737                 // parent_node first.
 738                 let base_node = if item.is_mod() && item.attrs.inner_docs {
 739                     self.mod_ids.last().copied()
 740                 } else {
 741                     parent_node
 742                 };
 743
 744                 // replace `Self` with suitable item's parent name
 745                 if path_str.starts_with("Self::") {
 746                     if let Some(ref name) = parent_name {
 747                         resolved_self = format!("{}::{}", name, &path_str[6..]);
 748                         path_str = &resolved_self;
 749                     }
 750                 }
 751
 752                 match disambiguator.map(Disambiguator::ns) {
 753                     Some(ns @ (ValueNS | TypeNS)) => {
 754                         match self.resolve(path_str, ns, &current_item, base_node, &extra_fragment)
 755                         {
 756                             Ok(res) => res,
 757                             Err(ErrorKind::ResolutionFailure) => {
 758                                 resolution_failure(cx, &item, path_str, &dox, link_range);
 759                                 // This could just be a normal link or a broken link
 760                                 // we could potentially check if something is
 761                                 // "intra-doc-link-like" and warn in that case.
 762                                 continue;
 763                             }
 764                             Err(ErrorKind::AnchorFailure(msg)) => {
 765                                 anchor_failure(cx, &item, &ori_link, &dox, link_range, msg);
 766                                 continue;
 767                             }
 768                         }
 769                     }
 770                     None => {
 771                         // Try everything!
 772                         let mut candidates = PerNS {
 773                             macro_ns: self
 774                                 .macro_resolve(path_str, base_node)
 775                                 .map(|res| (res, extra_fragment.clone())),
 776                             type_ns: match self.resolve(
 777                                 path_str,
 778                                 TypeNS,
 779                                 &current_item,
 780                                 base_node,
 781                                 &extra_fragment,
 782                             ) {
 783                                 Ok(res) => {
 784                                     debug!("got res in TypeNS: {:?}", res);
 785                                     Some(res)
 786                                 }
 787                                 Err(ErrorKind::AnchorFailure(msg)) => {
 788                                     anchor_failure(cx, &item, &ori_link, &dox, link_range, msg);
 789                                     continue;
 790                                 }
 791                                 Err(ErrorKind::ResolutionFailure) => None,
 792                             },
 793                             value_ns: match self.resolve(
 794                                 path_str,
 795                                 ValueNS,
 796                                 &current_item,
 797                                 base_node,
 798                                 &extra_fragment,
 799                             ) {
 800                                 Ok(res) => Some(res),
 801                                 Err(ErrorKind::AnchorFailure(msg)) => {
 802                                     anchor_failure(cx, &item, &ori_link, &dox, link_range, msg);
 803                                     continue;
 804                                 }
 805                                 Err(ErrorKind::ResolutionFailure) => None,
 806                             }
 807                             .and_then(|(res, fragment)| {
 808                                 // Constructors are picked up in the type namespace.
 809                                 match res {
 810                                     Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) => None,
 811                                     _ => match (fragment, extra_fragment) {
 812                                         (Some(fragment), Some(_)) => {
 813                                             // Shouldn't happen but who knows?
 814                                             Some((res, Some(fragment)))
 815                                         }
 816                                         (fragment, None) | (None, fragment) => {
 817                                             Some((res, fragment))
 818                                         }
 819                                     },
 820                                 }
 821                             }),
 822                         };
 823
 824                         if candidates.is_empty() {
 825                             resolution_failure(cx, &item, path_str, &dox, link_range);
 826                             // this could just be a normal link
 827                             continue;
 828                         }
 829
 830                         let len = candidates.clone().present_items().count();
 831
 832                         if len == 1 {
 833                             candidates.present_items().next().unwrap()
 834                         } else if len == 2 && is_derive_trait_collision(&candidates) {
 835                             candidates.type_ns.unwrap()
 836                         } else {
 837                             if is_derive_trait_collision(&candidates) {
 838                                 candidates.macro_ns = None;
 839                             }
 840                             let candidates =
 841                                 candidates.map(|candidate| candidate.map(|(res, _)| res));
 842                             ambiguity_error(
 843                                 cx,
 844                                 &item,
 845                                 path_str,
 846                                 &dox,
 847                                 link_range,
 848                                 candidates.present_items().collect(),
 849                             );
 850                             continue;
 851                         }
 852                     }
 853                     Some(MacroNS) => {
 854                         if let Some(res) = self.macro_resolve(path_str, base_node) {
 855                             (res, extra_fragment)
 856                         } else {
 857                             resolution_failure(cx, &item, path_str, &dox, link_range);
 858                             continue;
 859                         }
 860                     }
 861                 }
 862             };
 863
 864             // Check for a primitive which might conflict with a module
 865             // Report the ambiguity and require that the user specify which one they meant.
 866             // FIXME: could there ever be a primitive not in the type namespace?
 867             if matches!(
 868                 disambiguator,
 869                 None | Some(Disambiguator::Namespace(Namespace::TypeNS) | Disambiguator::Primitive)
 870             ) && !matches!(res, Res::PrimTy(_))
 871             {
 872                 if let Some((path, prim)) = is_primitive(path_str, TypeNS) {
 873                     // `prim@char`
 874                     if matches!(disambiguator, Some(Disambiguator::Primitive)) {
 875                         if fragment.is_some() {
 876                             anchor_failure(
 877                                 cx,
 878                                 &item,
 879                                 path_str,
 880                                 &dox,
 881                                 link_range,
 882                                 AnchorFailure::Primitive,
 883                             );
 884                             continue;
 885                         }
 886                         res = prim;
 887                         fragment = Some(path.to_owned());
 888                     } else {
 889                         // `[char]` when a `char` module is in scope
 890                         let candidates = vec![res, prim];
 891                         ambiguity_error(cx, &item, path_str, &dox, link_range, candidates);
 892                         continue;
 893                     }
 894                 }
 895             }
 896
 897             let report_mismatch = |specified: Disambiguator, resolved: Disambiguator| {
 898                 // The resolved item did not match the disambiguator; give a better error than 'not found'
 899                 let msg = format!("incompatible link kind for `{}`", path_str);
 900                 report_diagnostic(cx, &msg, &item, &dox, link_range.clone(), |diag, sp| {
 901                     let note = format!(
 902                         "this link resolved to {} {}, which is not {} {}",
 903                         resolved.article(),
 904                         resolved.descr(),
 905                         specified.article(),
 906                         specified.descr()
 907                     );
 908                     diag.note(&note);
 909                     suggest_disambiguator(resolved, diag, path_str, &dox, sp, &link_range);
 910                 });
 911             };
 912             if let Res::PrimTy(_) = res {
 913                 match disambiguator {
 914                     Some(Disambiguator::Primitive | Disambiguator::Namespace(_)) | None => {
 915                         item.attrs.links.push(ItemLink {
 916                             link: ori_link,
 917                             link_text: path_str.to_owned(),
 918                             did: None,
 919                             fragment,
 920                         });
 921                     }
 922                     Some(other) => {
 923                         report_mismatch(other, Disambiguator::Primitive);
 924                         continue;
 925                     }
 926                 }
 927             } else {
 928                 debug!("intra-doc link to {} resolved to {:?}", path_str, res);
 929
 930                 // Disallow e.g. linking to enums with `struct@`
 931                 if let Res::Def(kind, _) = res {
 932                     debug!("saw kind {:?} with disambiguator {:?}", kind, disambiguator);
 933                     match (self.kind_side_channel.take().unwrap_or(kind), disambiguator) {
 934                         | (DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst, Some(Disambiguator::Kind(DefKind::Const)))
 935                         // NOTE: this allows 'method' to mean both normal functions and associated functions
 936                         // This can't cause ambiguity because both are in the same namespace.
 937                         | (DefKind::Fn | DefKind::AssocFn, Some(Disambiguator::Kind(DefKind::Fn)))
 938                         // These are namespaces; allow anything in the namespace to match
 939                         | (_, Some(Disambiguator::Namespace(_)))
 940                         // If no disambiguator given, allow anything
 941                         | (_, None)
 942                         // All of these are valid, so do nothing
 943                         => {}
 944                         (actual, Some(Disambiguator::Kind(expected))) if actual == expected => {}
 945                         (_, Some(specified @ Disambiguator::Kind(_) | specified @ Disambiguator::Primitive)) => {
 946                             report_mismatch(specified, Disambiguator::Kind(kind));
 947                             continue;
 948                         }
 949                     }
 950                 }
 951
 952                 // item can be non-local e.g. when using #[doc(primitive = "pointer")]
 953                 if let Some((src_id, dst_id)) = res
 954                     .opt_def_id()
 955                     .and_then(|def_id| def_id.as_local())
 956                     .and_then(|dst_id| item.def_id.as_local().map(|src_id| (src_id, dst_id)))
 957                 {
 958                     use rustc_hir::def_id::LOCAL_CRATE;
 959
 960                     let hir_src = self.cx.tcx.hir().local_def_id_to_hir_id(src_id);
 961                     let hir_dst = self.cx.tcx.hir().local_def_id_to_hir_id(dst_id);
 962
 963                     if self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_src)
 964                         && !self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_dst)
 965                     {
 966                         privacy_error(cx, &item, &path_str, &dox, link_range);
 967                         continue;
 968                     }
 969                 }
 970                 let id = register_res(cx, res);
 971                 item.attrs.links.push(ItemLink {
 972                     link: ori_link,
 973                     link_text,
 974                     did: Some(id),
 975                     fragment,
 976                 });
 977             }
 978         }
 979
 980         if item.is_mod() && !item.attrs.inner_docs {
 981             self.mod_ids.push(item.def_id);
 982         }
 983
 984         if item.is_mod() {
 985             let ret = self.fold_item_recur(item);
 986
 987             self.mod_ids.pop();
 988
 989             ret
 990         } else {
 991             self.fold_item_recur(item)
 992         }
 993     }
 994 }
 995
 996 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 997 enum Disambiguator {
 998     Primitive,
 999     Kind(DefKind),
1000     Namespace(Namespace),
1001 }
1002
1003 impl Disambiguator {
1004     /// (disambiguator, path_str)
1005     fn from_str(link: &str) -> Result<(Self, &str), ()> {
1006         use Disambiguator::{Kind, Namespace as NS, Primitive};
1007
1008         let find_suffix = || {
1009             let suffixes = [
1010                 ("!()", DefKind::Macro(MacroKind::Bang)),
1011                 ("()", DefKind::Fn),
1012                 ("!", DefKind::Macro(MacroKind::Bang)),
1013             ];
1014             for &(suffix, kind) in &suffixes {
1015                 if link.ends_with(suffix) {
1016                     return Ok((Kind(kind), link.trim_end_matches(suffix)));
1017                 }
1018             }
1019             Err(())
1020         };
1021
1022         if let Some(idx) = link.find('@') {
1023             let (prefix, rest) = link.split_at(idx);
1024             let d = match prefix {
1025                 "struct" => Kind(DefKind::Struct),
1026                 "enum" => Kind(DefKind::Enum),
1027                 "trait" => Kind(DefKind::Trait),
1028                 "union" => Kind(DefKind::Union),
1029                 "module" | "mod" => Kind(DefKind::Mod),
1030                 "const" | "constant" => Kind(DefKind::Const),
1031                 "static" => Kind(DefKind::Static),
1032                 "function" | "fn" | "method" => Kind(DefKind::Fn),
1033                 "derive" => Kind(DefKind::Macro(MacroKind::Derive)),
1034                 "type" => NS(Namespace::TypeNS),
1035                 "value" => NS(Namespace::ValueNS),
1036                 "macro" => NS(Namespace::MacroNS),
1037                 "prim" | "primitive" => Primitive,
1038                 _ => return find_suffix(),
1039             };
1040             Ok((d, &rest[1..]))
1041         } else {
1042             find_suffix()
1043         }
1044     }
1045
1046     /// WARNING: panics on `Res::Err`
1047     fn from_res(res: Res) -> Self {
1048         match res {
1049             Res::Def(kind, _) => Disambiguator::Kind(kind),
1050             Res::PrimTy(_) => Disambiguator::Primitive,
1051             _ => Disambiguator::Namespace(res.ns().expect("can't call `from_res` on Res::err")),
1052         }
1053     }
1054
1055     /// Return (description of the change, suggestion)
1056     fn display_for(self, path_str: &str) -> (&'static str, String) {
1057         const PREFIX: &str = "prefix with the item kind";
1058         const FUNCTION: &str = "add parentheses";
1059         const MACRO: &str = "add an exclamation mark";
1060
1061         let kind = match self {
1062             Disambiguator::Primitive => return (PREFIX, format!("prim@{}", path_str)),
1063             Disambiguator::Kind(kind) => kind,
1064             Disambiguator::Namespace(_) => panic!("display_for cannot be used on namespaces"),
1065         };
1066         if kind == DefKind::Macro(MacroKind::Bang) {
1067             return (MACRO, format!("{}!", path_str));
1068         } else if kind == DefKind::Fn || kind == DefKind::AssocFn {
1069             return (FUNCTION, format!("{}()", path_str));
1070         }
1071
1072         let prefix = match kind {
1073             DefKind::Struct => "struct",
1074             DefKind::Enum => "enum",
1075             DefKind::Trait => "trait",
1076             DefKind::Union => "union",
1077             DefKind::Mod => "mod",
1078             DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst => {
1079                 "const"
1080             }
1081             DefKind::Static => "static",
1082             DefKind::Macro(MacroKind::Derive) => "derive",
1083             // Now handle things that don't have a specific disambiguator
1084             _ => match kind
1085                 .ns()
1086                 .expect("tried to calculate a disambiguator for a def without a namespace?")
1087             {
1088                 Namespace::TypeNS => "type",
1089                 Namespace::ValueNS => "value",
1090                 Namespace::MacroNS => "macro",
1091             },
1092         };
1093
1094         // FIXME: if this is an implied shortcut link, it's bad style to suggest `@`
1095         (PREFIX, format!("{}@{}", prefix, path_str))
1096     }
1097
1098     fn ns(self) -> Namespace {
1099         match self {
1100             Self::Namespace(n) => n,
1101             Self::Kind(k) => {
1102                 k.ns().expect("only DefKinds with a valid namespace can be disambiguators")
1103             }
1104             Self::Primitive => TypeNS,
1105         }
1106     }
1107
1108     fn article(self) -> &'static str {
1109         match self {
1110             Self::Namespace(_) => panic!("article() doesn't make sense for namespaces"),
1111             Self::Kind(k) => k.article(),
1112             Self::Primitive => "a",
1113         }
1114     }
1115
1116     fn descr(self) -> &'static str {
1117         match self {
1118             Self::Namespace(n) => n.descr(),
1119             // HACK(jynelson): by looking at the source I saw the DefId we pass
1120             // for `expected.descr()` doesn't matter, since it's not a crate
1121             Self::Kind(k) => k.descr(DefId::local(hir::def_id::DefIndex::from_usize(0))),
1122             Self::Primitive => "builtin type",
1123         }
1124     }
1125 }
1126
1127 /// Reports a diagnostic for an intra-doc link.
1128 ///
1129 /// If no link range is provided, or the source span of the link cannot be determined, the span of
1130 /// the entire documentation block is used for the lint. If a range is provided but the span
1131 /// calculation fails, a note is added to the diagnostic pointing to the link in the markdown.
1132 ///
1133 /// The `decorate` callback is invoked in all cases to allow further customization of the
1134 /// diagnostic before emission. If the span of the link was able to be determined, the second
1135 /// parameter of the callback will contain it, and the primary span of the diagnostic will be set
1136 /// to it.
1137 fn report_diagnostic(
1138     cx: &DocContext<'_>,
1139     msg: &str,
1140     item: &Item,
1141     dox: &str,
1142     link_range: Option<Range<usize>>,
1143     decorate: impl FnOnce(&mut DiagnosticBuilder<'_>, Option<rustc_span::Span>),
1144 ) {
1145     let hir_id = match cx.as_local_hir_id(item.def_id) {
1146         Some(hir_id) => hir_id,
1147         None => {
1148             // If non-local, no need to check anything.
1149             info!("ignoring warning from parent crate: {}", msg);
1150             return;
1151         }
1152     };
1153
1154     let attrs = &item.attrs;
1155     let sp = span_of_attrs(attrs).unwrap_or(item.source.span());
1156
1157     cx.tcx.struct_span_lint_hir(lint::builtin::BROKEN_INTRA_DOC_LINKS, hir_id, sp, |lint| {
1158         let mut diag = lint.build(msg);
1159
1160         let span = link_range
1161             .as_ref()
1162             .and_then(|range| super::source_span_for_markdown_range(cx, dox, range, attrs));
1163
1164         if let Some(link_range) = link_range {
1165             if let Some(sp) = span {
1166                 diag.set_span(sp);
1167             } else {
1168                 // blah blah blah\nblah\nblah [blah] blah blah\nblah blah
1169                 //                       ^     ~~~~
1170                 //                       |     link_range
1171                 //                       last_new_line_offset
1172                 let last_new_line_offset = dox[..link_range.start].rfind('\n').map_or(0, |n| n + 1);
1173                 let line = dox[last_new_line_offset..].lines().next().unwrap_or("");
1174
1175                 // Print the line containing the `link_range` and manually mark it with '^'s.
1176                 diag.note(&format!(
1177                     "the link appears in this line:\n\n{line}\n\
1178                      {indicator: <before$}{indicator:^<found$}",
1179                     line = line,
1180                     indicator = "",
1181                     before = link_range.start - last_new_line_offset,
1182                     found = link_range.len(),
1183                 ));
1184             }
1185         }
1186
1187         decorate(&mut diag, span);
1188
1189         diag.emit();
1190     });
1191 }
1192
1193 fn resolution_failure(
1194     cx: &DocContext<'_>,
1195     item: &Item,
1196     path_str: &str,
1197     dox: &str,
1198     link_range: Option<Range<usize>>,
1199 ) {
1200     report_diagnostic(
1201         cx,
1202         &format!("unresolved link to `{}`", path_str),
1203         item,
1204         dox,
1205         link_range,
1206         |diag, sp| {
1207             if let Some(sp) = sp {
1208                 diag.span_label(sp, "unresolved link");
1209             }
1210
1211             diag.help(r#"to escape `[` and `]` characters, add '\' before them like `\[` or `\]`"#);
1212         },
1213     );
1214 }
1215
1216 fn anchor_failure(
1217     cx: &DocContext<'_>,
1218     item: &Item,
1219     path_str: &str,
1220     dox: &str,
1221     link_range: Option<Range<usize>>,
1222     failure: AnchorFailure,
1223 ) {
1224     let msg = match failure {
1225         AnchorFailure::MultipleAnchors => format!("`{}` contains multiple anchors", path_str),
1226         AnchorFailure::Primitive
1227         | AnchorFailure::Variant
1228         | AnchorFailure::AssocConstant
1229         | AnchorFailure::AssocType
1230         | AnchorFailure::Field
1231         | AnchorFailure::Method => {
1232             let kind = match failure {
1233                 AnchorFailure::Primitive => "primitive type",
1234                 AnchorFailure::Variant => "enum variant",
1235                 AnchorFailure::AssocConstant => "associated constant",
1236                 AnchorFailure::AssocType => "associated type",
1237                 AnchorFailure::Field => "struct field",
1238                 AnchorFailure::Method => "method",
1239                 AnchorFailure::MultipleAnchors => unreachable!("should be handled already"),
1240             };
1241
1242             format!(
1243                 "`{}` contains an anchor, but links to {kind}s are already anchored",
1244                 path_str,
1245                 kind = kind
1246             )
1247         }
1248     };
1249
1250     report_diagnostic(cx, &msg, item, dox, link_range, |diag, sp| {
1251         if let Some(sp) = sp {
1252             diag.span_label(sp, "contains invalid anchor");
1253         }
1254     });
1255 }
1256
1257 fn ambiguity_error(
1258     cx: &DocContext<'_>,
1259     item: &Item,
1260     path_str: &str,
1261     dox: &str,
1262     link_range: Option<Range<usize>>,
1263     candidates: Vec<Res>,
1264 ) {
1265     let mut msg = format!("`{}` is ", path_str);
1266
1267     match candidates.as_slice() {
1268         [first_def, second_def] => {
1269             msg += &format!(
1270                 "both {} {} and {} {}",
1271                 first_def.article(),
1272                 first_def.descr(),
1273                 second_def.article(),
1274                 second_def.descr(),
1275             );
1276         }
1277         _ => {
1278             let mut candidates = candidates.iter().peekable();
1279             while let Some(res) = candidates.next() {
1280                 if candidates.peek().is_some() {
1281                     msg += &format!("{} {}, ", res.article(), res.descr());
1282                 } else {
1283                     msg += &format!("and {} {}", res.article(), res.descr());
1284                 }
1285             }
1286         }
1287     }
1288
1289     report_diagnostic(cx, &msg, item, dox, link_range.clone(), |diag, sp| {
1290         if let Some(sp) = sp {
1291             diag.span_label(sp, "ambiguous link");
1292         } else {
1293             diag.note("ambiguous link");
1294         }
1295
1296         for res in candidates {
1297             let disambiguator = Disambiguator::from_res(res);
1298             suggest_disambiguator(disambiguator, diag, path_str, dox, sp, &link_range);
1299         }
1300     });
1301 }
1302
1303 fn suggest_disambiguator(
1304     disambiguator: Disambiguator,
1305     diag: &mut DiagnosticBuilder<'_>,
1306     path_str: &str,
1307     dox: &str,
1308     sp: Option<rustc_span::Span>,
1309     link_range: &Option<Range<usize>>,
1310 ) {
1311     let (action, mut suggestion) = disambiguator.display_for(path_str);
1312     let help = format!("to link to the {}, {}", disambiguator.descr(), action);
1313
1314     if let Some(sp) = sp {
1315         let link_range = link_range.as_ref().expect("must have a link range if we have a span");
1316         if dox.bytes().nth(link_range.start) == Some(b'`') {
1317             suggestion = format!("`{}`", suggestion);
1318         }
1319
1320         diag.span_suggestion(sp, &help, suggestion, Applicability::MaybeIncorrect);
1321     } else {
1322         diag.help(&format!("{}: {}", help, suggestion));
1323     }
1324 }
1325
1326 fn privacy_error(
1327     cx: &DocContext<'_>,
1328     item: &Item,
1329     path_str: &str,
1330     dox: &str,
1331     link_range: Option<Range<usize>>,
1332 ) {
1333     let item_name = item.name.as_deref().unwrap_or("<unknown>");
1334     let msg =
1335         format!("public documentation for `{}` links to private item `{}`", item_name, path_str);
1336
1337     report_diagnostic(cx, &msg, item, dox, link_range, |diag, sp| {
1338         if let Some(sp) = sp {
1339             diag.span_label(sp, "this item is private");
1340         }
1341
1342         let note_msg = if cx.render_options.document_private {
1343             "this link resolves only because you passed `--document-private-items`, but will break without"
1344         } else {
1345             "this link will resolve properly if you pass `--document-private-items`"
1346         };
1347         diag.note(note_msg);
1348     });
1349 }
1350
1351 /// Given an enum variant's res, return the res of its enum and the associated fragment.
1352 fn handle_variant(
1353     cx: &DocContext<'_>,
1354     res: Res,
1355     extra_fragment: &Option<String>,
1356 ) -> Result<(Res, Option<String>), ErrorKind> {
1357     use rustc_middle::ty::DefIdTree;
1358
1359     if extra_fragment.is_some() {
1360         return Err(ErrorKind::AnchorFailure(AnchorFailure::Variant));
1361     }
1362     let parent = if let Some(parent) = cx.tcx.parent(res.def_id()) {
1363         parent
1364     } else {
1365         return Err(ErrorKind::ResolutionFailure);
1366     };
1367     let parent_def = Res::Def(DefKind::Enum, parent);
1368     let variant = cx.tcx.expect_variant_res(res);
1369     Ok((parent_def, Some(format!("variant.{}", variant.ident.name))))
1370 }
1371
1372 const PRIMITIVES: &[(&str, Res)] = &[
1373     ("u8", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U8))),
1374     ("u16", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U16))),
1375     ("u32", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U32))),
1376     ("u64", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U64))),
1377     ("u128", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::U128))),
1378     ("usize", Res::PrimTy(hir::PrimTy::Uint(rustc_ast::UintTy::Usize))),
1379     ("i8", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I8))),
1380     ("i16", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I16))),
1381     ("i32", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I32))),
1382     ("i64", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I64))),
1383     ("i128", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::I128))),
1384     ("isize", Res::PrimTy(hir::PrimTy::Int(rustc_ast::IntTy::Isize))),
1385     ("f32", Res::PrimTy(hir::PrimTy::Float(rustc_ast::FloatTy::F32))),
1386     ("f64", Res::PrimTy(hir::PrimTy::Float(rustc_ast::FloatTy::F64))),
1387     ("str", Res::PrimTy(hir::PrimTy::Str)),
1388     ("bool", Res::PrimTy(hir::PrimTy::Bool)),
1389     ("true", Res::PrimTy(hir::PrimTy::Bool)),
1390     ("false", Res::PrimTy(hir::PrimTy::Bool)),
1391     ("char", Res::PrimTy(hir::PrimTy::Char)),
1392 ];
1393
1394 fn is_primitive(path_str: &str, ns: Namespace) -> Option<(&'static str, Res)> {
1395     if ns == TypeNS {
1396         PRIMITIVES
1397             .iter()
1398             .filter(|x| x.0 == path_str)
1399             .copied()
1400             .map(|x| if x.0 == "true" || x.0 == "false" { ("bool", x.1) } else { x })
1401             .next()
1402     } else {
1403         None
1404     }
1405 }
1406
1407 fn primitive_impl(cx: &DocContext<'_>, path_str: &str) -> Option<&'static SmallVec<[DefId; 4]>> {
1408     Some(PrimitiveType::from_symbol(Symbol::intern(path_str))?.impls(cx.tcx))
1409 }