src/librustdoc/passes/collect_intra_doc_links.rs

   1 //! This module implements [RFC 1946]: Intra-rustdoc-links
   2 //!
   3 //! [RFC 1946]: https://github.com/rust-lang/rfcs/blob/master/text/1946-intra-rustdoc-links.md
   4
   5 use rustc_ast as ast;
   6 use rustc_data_structures::{fx::FxHashMap, stable_set::FxHashSet};
   7 use rustc_errors::{Applicability, DiagnosticBuilder};
   8 use rustc_expand::base::SyntaxExtensionKind;
   9 use rustc_hir as hir;
  10 use rustc_hir::def::{
  11     DefKind,
  12     Namespace::{self, *},
  13     PerNS,
  14 };
  15 use rustc_hir::def_id::{CrateNum, DefId};
  16 use rustc_middle::ty::TyCtxt;
  17 use rustc_middle::{bug, ty};
  18 use rustc_resolve::ParentScope;
  19 use rustc_session::lint::Lint;
  20 use rustc_span::hygiene::{MacroKind, SyntaxContext};
  21 use rustc_span::symbol::{sym, Ident, Symbol};
  22 use rustc_span::DUMMY_SP;
  23 use smallvec::{smallvec, SmallVec};
  24
  25 use pulldown_cmark::LinkType;
  26
  27 use std::borrow::Cow;
  28 use std::cell::Cell;
  29 use std::convert::{TryFrom, TryInto};
  30 use std::mem;
  31 use std::ops::Range;
  32
  33 use crate::clean::{self, utils::find_nearest_parent_module, Crate, Item, ItemLink, PrimitiveType};
  34 use crate::core::DocContext;
  35 use crate::fold::DocFolder;
  36 use crate::html::markdown::{markdown_links, MarkdownLink};
  37 use crate::lint::{BROKEN_INTRA_DOC_LINKS, PRIVATE_INTRA_DOC_LINKS};
  38 use crate::passes::Pass;
  39
  40 use super::span_of_attrs;
  41
  42 crate const COLLECT_INTRA_DOC_LINKS: Pass = Pass {
  43     name: "collect-intra-doc-links",
  44     run: collect_intra_doc_links,
  45     description: "resolves intra-doc links",
  46 };
  47
  48 crate fn collect_intra_doc_links(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
  49     LinkCollector {
  50         cx,
  51         mod_ids: Vec::new(),
  52         kind_side_channel: Cell::new(None),
  53         visited_links: FxHashMap::default(),
  54     }
  55     .fold_crate(krate)
  56 }
  57
  58 /// Top-level errors emitted by this pass.
  59 enum ErrorKind<'a> {
  60     Resolve(Box<ResolutionFailure<'a>>),
  61     AnchorFailure(AnchorFailure),
  62 }
  63
  64 impl<'a> From<ResolutionFailure<'a>> for ErrorKind<'a> {
  65     fn from(err: ResolutionFailure<'a>) -> Self {
  66         ErrorKind::Resolve(box err)
  67     }
  68 }
  69
  70 #[derive(Copy, Clone, Debug, Hash)]
  71 enum Res {
  72     Def(DefKind, DefId),
  73     Primitive(PrimitiveType),
  74 }
  75
  76 type ResolveRes = rustc_hir::def::Res<rustc_ast::NodeId>;
  77
  78 impl Res {
  79     fn descr(self) -> &'static str {
  80         match self {
  81             Res::Def(kind, id) => ResolveRes::Def(kind, id).descr(),
  82             Res::Primitive(_) => "builtin type",
  83         }
  84     }
  85
  86     fn article(self) -> &'static str {
  87         match self {
  88             Res::Def(kind, id) => ResolveRes::Def(kind, id).article(),
  89             Res::Primitive(_) => "a",
  90         }
  91     }
  92
  93     fn name(self, tcx: TyCtxt<'_>) -> String {
  94         match self {
  95             Res::Def(_, id) => tcx.item_name(id).to_string(),
  96             Res::Primitive(prim) => prim.as_str().to_string(),
  97         }
  98     }
  99
 100     fn def_id(self) -> DefId {
 101         self.opt_def_id().expect("called def_id() on a primitive")
 102     }
 103
 104     fn opt_def_id(self) -> Option<DefId> {
 105         match self {
 106             Res::Def(_, id) => Some(id),
 107             Res::Primitive(_) => None,
 108         }
 109     }
 110
 111     fn as_hir_res(self) -> Option<rustc_hir::def::Res> {
 112         match self {
 113             Res::Def(kind, id) => Some(rustc_hir::def::Res::Def(kind, id)),
 114             // FIXME: maybe this should handle the subset of PrimitiveType that fits into hir::PrimTy?
 115             Res::Primitive(_) => None,
 116         }
 117     }
 118 }
 119
 120 impl TryFrom<ResolveRes> for Res {
 121     type Error = ();
 122
 123     fn try_from(res: ResolveRes) -> Result<Self, ()> {
 124         use rustc_hir::def::Res::*;
 125         match res {
 126             Def(kind, id) => Ok(Res::Def(kind, id)),
 127             PrimTy(prim) => Ok(Res::Primitive(PrimitiveType::from_hir(prim))),
 128             // e.g. `#[derive]`
 129             NonMacroAttr(..) | Err => Result::Err(()),
 130             other => bug!("unrecognized res {:?}", other),
 131         }
 132     }
 133 }
 134
 135 /// A link failed to resolve.
 136 #[derive(Debug)]
 137 enum ResolutionFailure<'a> {
 138     /// This resolved, but with the wrong namespace.
 139     WrongNamespace {
 140         /// What the link resolved to.
 141         res: Res,
 142         /// The expected namespace for the resolution, determined from the link's disambiguator.
 143         ///
 144         /// E.g., for `[fn@Result]` this is [`Namespace::ValueNS`],
 145         /// even though `Result`'s actual namespace is [`Namespace::TypeNS`].
 146         expected_ns: Namespace,
 147     },
 148     /// The link failed to resolve. [`resolution_failure`] should look to see if there's
 149     /// a more helpful error that can be given.
 150     NotResolved {
 151         /// The scope the link was resolved in.
 152         module_id: DefId,
 153         /// If part of the link resolved, this has the `Res`.
 154         ///
 155         /// In `[std::io::Error::x]`, `std::io::Error` would be a partial resolution.
 156         partial_res: Option<Res>,
 157         /// The remaining unresolved path segments.
 158         ///
 159         /// In `[std::io::Error::x]`, `x` would be unresolved.
 160         unresolved: Cow<'a, str>,
 161     },
 162     /// This happens when rustdoc can't determine the parent scope for an item.
 163     /// It is always a bug in rustdoc.
 164     NoParentItem,
 165     /// This link has malformed generic parameters; e.g., the angle brackets are unbalanced.
 166     MalformedGenerics(MalformedGenerics),
 167     /// Used to communicate that this should be ignored, but shouldn't be reported to the user.
 168     ///
 169     /// This happens when there is no disambiguator and one of the namespaces
 170     /// failed to resolve.
 171     Dummy,
 172 }
 173
 174 #[derive(Debug)]
 175 enum MalformedGenerics {
 176     /// This link has unbalanced angle brackets.
 177     ///
 178     /// For example, `Vec<T` should trigger this, as should `Vec<T>>`.
 179     UnbalancedAngleBrackets,
 180     /// The generics are not attached to a type.
 181     ///
 182     /// For example, `<T>` should trigger this.
 183     ///
 184     /// This is detected by checking if the path is empty after the generics are stripped.
 185     MissingType,
 186     /// The link uses fully-qualified syntax, which is currently unsupported.
 187     ///
 188     /// For example, `<Vec as IntoIterator>::into_iter` should trigger this.
 189     ///
 190     /// This is detected by checking if ` as ` (the keyword `as` with spaces around it) is inside
 191     /// angle brackets.
 192     HasFullyQualifiedSyntax,
 193     /// The link has an invalid path separator.
 194     ///
 195     /// For example, `Vec:<T>:new()` should trigger this. Note that `Vec:new()` will **not**
 196     /// trigger this because it has no generics and thus [`strip_generics_from_path`] will not be
 197     /// called.
 198     ///
 199     /// Note that this will also **not** be triggered if the invalid path separator is inside angle
 200     /// brackets because rustdoc mostly ignores what's inside angle brackets (except for
 201     /// [`HasFullyQualifiedSyntax`](MalformedGenerics::HasFullyQualifiedSyntax)).
 202     ///
 203     /// This is detected by checking if there is a colon followed by a non-colon in the link.
 204     InvalidPathSeparator,
 205     /// The link has too many angle brackets.
 206     ///
 207     /// For example, `Vec<<T>>` should trigger this.
 208     TooManyAngleBrackets,
 209     /// The link has empty angle brackets.
 210     ///
 211     /// For example, `Vec<>` should trigger this.
 212     EmptyAngleBrackets,
 213 }
 214
 215 impl ResolutionFailure<'a> {
 216     /// This resolved fully (not just partially) but is erroneous for some other reason
 217     ///
 218     /// Returns the full resolution of the link, if present.
 219     fn full_res(&self) -> Option<Res> {
 220         match self {
 221             Self::WrongNamespace { res, expected_ns: _ } => Some(*res),
 222             _ => None,
 223         }
 224     }
 225 }
 226
 227 enum AnchorFailure {
 228     /// User error: `[std#x#y]` is not valid
 229     MultipleAnchors,
 230     /// The anchor provided by the user conflicts with Rustdoc's generated anchor.
 231     ///
 232     /// This is an unfortunate state of affairs. Not every item that can be
 233     /// linked to has its own page; sometimes it is a subheading within a page,
 234     /// like for associated items. In those cases, rustdoc uses an anchor to
 235     /// link to the subheading. Since you can't have two anchors for the same
 236     /// link, Rustdoc disallows having a user-specified anchor.
 237     ///
 238     /// Most of the time this is fine, because you can just link to the page of
 239     /// the item if you want to provide your own anchor. For primitives, though,
 240     /// rustdoc uses the anchor as a side channel to know which page to link to;
 241     /// it doesn't show up in the generated link. Ideally, rustdoc would remove
 242     /// this limitation, allowing you to link to subheaders on primitives.
 243     RustdocAnchorConflict(Res),
 244 }
 245
 246 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 247 struct ResolutionInfo {
 248     module_id: DefId,
 249     dis: Option<Disambiguator>,
 250     path_str: String,
 251     extra_fragment: Option<String>,
 252 }
 253
 254 struct DiagnosticInfo<'a> {
 255     item: &'a Item,
 256     dox: &'a str,
 257     ori_link: &'a str,
 258     link_range: Range<usize>,
 259 }
 260
 261 #[derive(Clone, Debug, Hash)]
 262 struct CachedLink {
 263     pub res: (Res, Option<String>),
 264     pub side_channel: Option<(DefKind, DefId)>,
 265 }
 266
 267 struct LinkCollector<'a, 'tcx> {
 268     cx: &'a mut DocContext<'tcx>,
 269     /// A stack of modules used to decide what scope to resolve in.
 270     ///
 271     /// The last module will be used if the parent scope of the current item is
 272     /// unknown.
 273     mod_ids: Vec<DefId>,
 274     /// This is used to store the kind of associated items,
 275     /// because `clean` and the disambiguator code expect them to be different.
 276     /// See the code for associated items on inherent impls for details.
 277     kind_side_channel: Cell<Option<(DefKind, DefId)>>,
 278     /// Cache the resolved links so we can avoid resolving (and emitting errors for) the same link.
 279     /// The link will be `None` if it could not be resolved (i.e. the error was cached).
 280     visited_links: FxHashMap<ResolutionInfo, Option<CachedLink>>,
 281 }
 282
 283 impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
 284     /// Given a full link, parse it as an [enum struct variant].
 285     ///
 286     /// In particular, this will return an error whenever there aren't three
 287     /// full path segments left in the link.
 288     ///
 289     /// [enum struct variant]: hir::VariantData::Struct
 290     fn variant_field(
 291         &self,
 292         path_str: &'path str,
 293         module_id: DefId,
 294     ) -> Result<(Res, Option<String>), ErrorKind<'path>> {
 295         let tcx = self.cx.tcx;
 296         let no_res = || ResolutionFailure::NotResolved {
 297             module_id,
 298             partial_res: None,
 299             unresolved: path_str.into(),
 300         };
 301
 302         debug!("looking for enum variant {}", path_str);
 303         let mut split = path_str.rsplitn(3, "::");
 304         let (variant_field_str, variant_field_name) = split
 305             .next()
 306             .map(|f| (f, Symbol::intern(f)))
 307             .expect("fold_item should ensure link is non-empty");
 308         let (variant_str, variant_name) =
 309             // we're not sure this is a variant at all, so use the full string
 310             // If there's no second component, the link looks like `[path]`.
 311             // So there's no partial res and we should say the whole link failed to resolve.
 312             split.next().map(|f| (f, Symbol::intern(f))).ok_or_else(no_res)?;
 313         let path = split
 314             .next()
 315             .map(|f| f.to_owned())
 316             // If there's no third component, we saw `[a::b]` before and it failed to resolve.
 317             // So there's no partial res.
 318             .ok_or_else(no_res)?;
 319         let ty_res = self
 320             .cx
 321             .enter_resolver(|resolver| {
 322                 resolver.resolve_str_path_error(DUMMY_SP, &path, TypeNS, module_id)
 323             })
 324             .and_then(|(_, res)| res.try_into())
 325             .map_err(|()| no_res())?;
 326
 327         match ty_res {
 328             Res::Def(DefKind::Enum, did) => {
 329                 if tcx
 330                     .inherent_impls(did)
 331                     .iter()
 332                     .flat_map(|imp| tcx.associated_items(*imp).in_definition_order())
 333                     .any(|item| item.ident.name == variant_name)
 334                 {
 335                     // This is just to let `fold_item` know that this shouldn't be considered;
 336                     // it's a bug for the error to make it to the user
 337                     return Err(ResolutionFailure::Dummy.into());
 338                 }
 339                 match tcx.type_of(did).kind() {
 340                     ty::Adt(def, _) if def.is_enum() => {
 341                         if def.all_fields().any(|item| item.ident.name == variant_field_name) {
 342                             Ok((
 343                                 ty_res,
 344                                 Some(format!(
 345                                     "variant.{}.field.{}",
 346                                     variant_str, variant_field_name
 347                                 )),
 348                             ))
 349                         } else {
 350                             Err(ResolutionFailure::NotResolved {
 351                                 module_id,
 352                                 partial_res: Some(Res::Def(DefKind::Enum, def.did)),
 353                                 unresolved: variant_field_str.into(),
 354                             }
 355                             .into())
 356                         }
 357                     }
 358                     _ => unreachable!(),
 359                 }
 360             }
 361             _ => Err(ResolutionFailure::NotResolved {
 362                 module_id,
 363                 partial_res: Some(ty_res),
 364                 unresolved: variant_str.into(),
 365             }
 366             .into()),
 367         }
 368     }
 369
 370     /// Given a primitive type, try to resolve an associated item.
 371     fn resolve_primitive_associated_item(
 372         &self,
 373         prim_ty: PrimitiveType,
 374         ns: Namespace,
 375         item_name: Symbol,
 376     ) -> Option<(Res, String, Option<(DefKind, DefId)>)> {
 377         let tcx = self.cx.tcx;
 378
 379         prim_ty.impls(tcx).into_iter().find_map(|&impl_| {
 380             tcx.associated_items(impl_)
 381                 .find_by_name_and_namespace(tcx, Ident::with_dummy_span(item_name), ns, impl_)
 382                 .map(|item| {
 383                     let kind = item.kind;
 384                     let out = match kind {
 385                         ty::AssocKind::Fn => "method",
 386                         ty::AssocKind::Const => "associatedconstant",
 387                         ty::AssocKind::Type => "associatedtype",
 388                     };
 389                     let fragment = format!("{}#{}.{}", prim_ty.as_str(), out, item_name);
 390                     (Res::Primitive(prim_ty), fragment, Some((kind.as_def_kind(), item.def_id)))
 391                 })
 392         })
 393     }
 394
 395     /// Resolves a string as a macro.
 396     ///
 397     /// FIXME(jynelson): Can this be unified with `resolve()`?
 398     fn resolve_macro(
 399         &self,
 400         path_str: &'a str,
 401         module_id: DefId,
 402     ) -> Result<Res, ResolutionFailure<'a>> {
 403         let path = ast::Path::from_ident(Ident::from_str(path_str));
 404         self.cx.enter_resolver(|resolver| {
 405             // FIXME(jynelson): does this really need 3 separate lookups?
 406             if let Ok((Some(ext), res)) = resolver.resolve_macro_path(
 407                 &path,
 408                 None,
 409                 &ParentScope::module(resolver.graph_root(), resolver),
 410                 false,
 411                 false,
 412             ) {
 413                 if let SyntaxExtensionKind::LegacyBang { .. } = ext.kind {
 414                     return Ok(res.try_into().unwrap());
 415                 }
 416             }
 417             if let Some(&res) = resolver.all_macros().get(&Symbol::intern(path_str)) {
 418                 return Ok(res.try_into().unwrap());
 419             }
 420             debug!("resolving {} as a macro in the module {:?}", path_str, module_id);
 421             if let Ok((_, res)) =
 422                 resolver.resolve_str_path_error(DUMMY_SP, path_str, MacroNS, module_id)
 423             {
 424                 // don't resolve builtins like `#[derive]`
 425                 if let Ok(res) = res.try_into() {
 426                     return Ok(res);
 427                 }
 428             }
 429             Err(ResolutionFailure::NotResolved {
 430                 module_id,
 431                 partial_res: None,
 432                 unresolved: path_str.into(),
 433             })
 434         })
 435     }
 436
 437     /// Convenience wrapper around `resolve_str_path_error`.
 438     ///
 439     /// This also handles resolving `true` and `false` as booleans.
 440     /// NOTE: `resolve_str_path_error` knows only about paths, not about types.
 441     /// Associated items will never be resolved by this function.
 442     fn resolve_path(&self, path_str: &str, ns: Namespace, module_id: DefId) -> Option<Res> {
 443         let result = self.cx.enter_resolver(|resolver| {
 444             resolver
 445                 .resolve_str_path_error(DUMMY_SP, &path_str, ns, module_id)
 446                 .and_then(|(_, res)| res.try_into())
 447         });
 448         debug!("{} resolved to {:?} in namespace {:?}", path_str, result, ns);
 449         match result {
 450             // resolver doesn't know about true, false, and types that aren't paths (e.g. `()`)
 451             // manually as bool
 452             Err(()) => resolve_primitive(path_str, ns),
 453             Ok(res) => Some(res),
 454         }
 455     }
 456
 457     /// Resolves a string as a path within a particular namespace. Returns an
 458     /// optional URL fragment in the case of variants and methods.
 459     fn resolve<'path>(
 460         &mut self,
 461         path_str: &'path str,
 462         ns: Namespace,
 463         module_id: DefId,
 464         extra_fragment: &Option<String>,
 465     ) -> Result<(Res, Option<String>), ErrorKind<'path>> {
 466         if let Some(res) = self.resolve_path(path_str, ns, module_id) {
 467             match res {
 468                 // FIXME(#76467): make this fallthrough to lookup the associated
 469                 // item a separate function.
 470                 Res::Def(DefKind::AssocFn | DefKind::AssocConst, _) => assert_eq!(ns, ValueNS),
 471                 Res::Def(DefKind::AssocTy, _) => assert_eq!(ns, TypeNS),
 472                 Res::Def(DefKind::Variant, _) => {
 473                     return handle_variant(self.cx, res, extra_fragment);
 474                 }
 475                 // Not a trait item; just return what we found.
 476                 Res::Primitive(ty) => {
 477                     if extra_fragment.is_some() {
 478                         return Err(ErrorKind::AnchorFailure(
 479                             AnchorFailure::RustdocAnchorConflict(res),
 480                         ));
 481                     }
 482                     return Ok((res, Some(ty.as_str().to_owned())));
 483                 }
 484                 _ => return Ok((res, extra_fragment.clone())),
 485             }
 486         }
 487
 488         // Try looking for methods and associated items.
 489         let mut split = path_str.rsplitn(2, "::");
 490         // NB: `split`'s first element is always defined, even if the delimiter was not present.
 491         // NB: `item_str` could be empty when resolving in the root namespace (e.g. `::std`).
 492         let item_str = split.next().unwrap();
 493         let item_name = Symbol::intern(item_str);
 494         let path_root = split
 495             .next()
 496             .map(|f| f.to_owned())
 497             // If there's no `::`, it's not an associated item.
 498             // So we can be sure that `rustc_resolve` was accurate when it said it wasn't resolved.
 499             .ok_or_else(|| {
 500                 debug!("found no `::`, assumming {} was correctly not in scope", item_name);
 501                 ResolutionFailure::NotResolved {
 502                     module_id,
 503                     partial_res: None,
 504                     unresolved: item_str.into(),
 505                 }
 506             })?;
 507
 508         // FIXME(#83862): this arbitrarily gives precedence to primitives over modules to support
 509         // links to primitives when `#[doc(primitive)]` is present. It should give an ambiguity
 510         // error instead and special case *only* modules with `#[doc(primitive)]`, not all
 511         // primitives.
 512         resolve_primitive(&path_root, TypeNS)
 513             .or_else(|| self.resolve_path(&path_root, TypeNS, module_id))
 514             .and_then(|ty_res| {
 515                 let (res, fragment, side_channel) =
 516                     self.resolve_associated_item(ty_res, item_name, ns, module_id)?;
 517                 let result = if extra_fragment.is_some() {
 518                     let diag_res = side_channel.map_or(res, |(k, r)| Res::Def(k, r));
 519                     Err(ErrorKind::AnchorFailure(AnchorFailure::RustdocAnchorConflict(diag_res)))
 520                 } else {
 521                     // HACK(jynelson): `clean` expects the type, not the associated item
 522                     // but the disambiguator logic expects the associated item.
 523                     // Store the kind in a side channel so that only the disambiguator logic looks at it.
 524                     if let Some((kind, id)) = side_channel {
 525                         self.kind_side_channel.set(Some((kind, id)));
 526                     }
 527                     Ok((res, Some(fragment)))
 528                 };
 529                 Some(result)
 530             })
 531             .unwrap_or_else(|| {
 532                 if ns == Namespace::ValueNS {
 533                     self.variant_field(path_str, module_id)
 534                 } else {
 535                     Err(ResolutionFailure::NotResolved {
 536                         module_id,
 537                         partial_res: None,
 538                         unresolved: path_root.into(),
 539                     }
 540                     .into())
 541                 }
 542             })
 543     }
 544
 545     /// Returns:
 546     /// - None if no associated item was found
 547     /// - Some((_, _, Some(_))) if an item was found and should go through a side channel
 548     /// - Some((_, _, None)) otherwise
 549     fn resolve_associated_item(
 550         &mut self,
 551         root_res: Res,
 552         item_name: Symbol,
 553         ns: Namespace,
 554         module_id: DefId,
 555     ) -> Option<(Res, String, Option<(DefKind, DefId)>)> {
 556         let tcx = self.cx.tcx;
 557
 558         match root_res {
 559             Res::Primitive(prim) => self.resolve_primitive_associated_item(prim, ns, item_name),
 560             Res::Def(
 561                 DefKind::Struct
 562                 | DefKind::Union
 563                 | DefKind::Enum
 564                 | DefKind::TyAlias
 565                 | DefKind::ForeignTy,
 566                 did,
 567             ) => {
 568                 debug!("looking for associated item named {} for item {:?}", item_name, did);
 569                 // Checks if item_name belongs to `impl SomeItem`
 570                 let assoc_item = tcx
 571                     .inherent_impls(did)
 572                     .iter()
 573                     .flat_map(|&imp| {
 574                         tcx.associated_items(imp).find_by_name_and_namespace(
 575                             tcx,
 576                             Ident::with_dummy_span(item_name),
 577                             ns,
 578                             imp,
 579                         )
 580                     })
 581                     .map(|item| (item.kind, item.def_id))
 582                     // There should only ever be one associated item that matches from any inherent impl
 583                     .next()
 584                     // Check if item_name belongs to `impl SomeTrait for SomeItem`
 585                     // FIXME(#74563): This gives precedence to `impl SomeItem`:
 586                     // Although having both would be ambiguous, use impl version for compatibility's sake.
 587                     // To handle that properly resolve() would have to support
 588                     // something like [`ambi_fn`](<SomeStruct as SomeTrait>::ambi_fn)
 589                     .or_else(|| {
 590                         let kind =
 591                             resolve_associated_trait_item(did, module_id, item_name, ns, self.cx);
 592                         debug!("got associated item kind {:?}", kind);
 593                         kind
 594                     });
 595
 596                 if let Some((kind, id)) = assoc_item {
 597                     let out = match kind {
 598                         ty::AssocKind::Fn => "method",
 599                         ty::AssocKind::Const => "associatedconstant",
 600                         ty::AssocKind::Type => "associatedtype",
 601                     };
 602                     // HACK(jynelson): `clean` expects the type, not the associated item
 603                     // but the disambiguator logic expects the associated item.
 604                     // Store the kind in a side channel so that only the disambiguator logic looks at it.
 605                     return Some((
 606                         root_res,
 607                         format!("{}.{}", out, item_name),
 608                         Some((kind.as_def_kind(), id)),
 609                     ));
 610                 }
 611
 612                 if ns != Namespace::ValueNS {
 613                     return None;
 614                 }
 615                 debug!("looking for variants or fields named {} for {:?}", item_name, did);
 616                 // FIXME: this doesn't really belong in `associated_item` (maybe `variant_field` is better?)
 617                 // NOTE: it's different from variant_field because it resolves fields and variants,
 618                 // not variant fields (2 path segments, not 3).
 619                 let def = match tcx.type_of(did).kind() {
 620                     ty::Adt(def, _) => def,
 621                     _ => return None,
 622                 };
 623                 let field = if def.is_enum() {
 624                     def.all_fields().find(|item| item.ident.name == item_name)
 625                 } else {
 626                     def.non_enum_variant().fields.iter().find(|item| item.ident.name == item_name)
 627                 }?;
 628                 let kind = if def.is_enum() { DefKind::Variant } else { DefKind::Field };
 629                 Some((
 630                     root_res,
 631                     format!(
 632                         "{}.{}",
 633                         if def.is_enum() { "variant" } else { "structfield" },
 634                         field.ident
 635                     ),
 636                     Some((kind, field.did)),
 637                 ))
 638             }
 639             Res::Def(DefKind::Trait, did) => tcx
 640                 .associated_items(did)
 641                 .find_by_name_and_namespace(tcx, Ident::with_dummy_span(item_name), ns, did)
 642                 .map(|item| {
 643                     let kind = match item.kind {
 644                         ty::AssocKind::Const => "associatedconstant",
 645                         ty::AssocKind::Type => "associatedtype",
 646                         ty::AssocKind::Fn => {
 647                             if item.defaultness.has_value() {
 648                                 "method"
 649                             } else {
 650                                 "tymethod"
 651                             }
 652                         }
 653                     };
 654
 655                     let res = Res::Def(item.kind.as_def_kind(), item.def_id);
 656                     (res, format!("{}.{}", kind, item_name), None)
 657                 }),
 658             _ => None,
 659         }
 660     }
 661
 662     /// Used for reporting better errors.
 663     ///
 664     /// Returns whether the link resolved 'fully' in another namespace.
 665     /// 'fully' here means that all parts of the link resolved, not just some path segments.
 666     /// This returns the `Res` even if it was erroneous for some reason
 667     /// (such as having invalid URL fragments or being in the wrong namespace).
 668     fn check_full_res(
 669         &mut self,
 670         ns: Namespace,
 671         path_str: &str,
 672         module_id: DefId,
 673         extra_fragment: &Option<String>,
 674     ) -> Option<Res> {
 675         // resolve() can't be used for macro namespace
 676         let result = match ns {
 677             Namespace::MacroNS => self.resolve_macro(path_str, module_id).map_err(ErrorKind::from),
 678             Namespace::TypeNS | Namespace::ValueNS => {
 679                 self.resolve(path_str, ns, module_id, extra_fragment).map(|(res, _)| res)
 680             }
 681         };
 682
 683         let res = match result {
 684             Ok(res) => Some(res),
 685             Err(ErrorKind::Resolve(box kind)) => kind.full_res(),
 686             Err(ErrorKind::AnchorFailure(AnchorFailure::RustdocAnchorConflict(res))) => Some(res),
 687             Err(ErrorKind::AnchorFailure(AnchorFailure::MultipleAnchors)) => None,
 688         };
 689         self.kind_side_channel.take().map(|(kind, id)| Res::Def(kind, id)).or(res)
 690     }
 691 }
 692
 693 /// Look to see if a resolved item has an associated item named `item_name`.
 694 ///
 695 /// Given `[std::io::Error::source]`, where `source` is unresolved, this would
 696 /// find `std::error::Error::source` and return
 697 /// `<io::Error as error::Error>::source`.
 698 fn resolve_associated_trait_item(
 699     did: DefId,
 700     module: DefId,
 701     item_name: Symbol,
 702     ns: Namespace,
 703     cx: &mut DocContext<'_>,
 704 ) -> Option<(ty::AssocKind, DefId)> {
 705     // FIXME: this should also consider blanket impls (`impl<T> X for T`). Unfortunately
 706     // `get_auto_trait_and_blanket_impls` is broken because the caching behavior is wrong. In the
 707     // meantime, just don't look for these blanket impls.
 708
 709     // Next consider explicit impls: `impl MyTrait for MyType`
 710     // Give precedence to inherent impls.
 711     let traits = traits_implemented_by(cx, did, module);
 712     debug!("considering traits {:?}", traits);
 713     let mut candidates = traits.iter().filter_map(|&trait_| {
 714         cx.tcx
 715             .associated_items(trait_)
 716             .find_by_name_and_namespace(cx.tcx, Ident::with_dummy_span(item_name), ns, trait_)
 717             .map(|assoc| (assoc.kind, assoc.def_id))
 718     });
 719     // FIXME(#74563): warn about ambiguity
 720     debug!("the candidates were {:?}", candidates.clone().collect::<Vec<_>>());
 721     candidates.next()
 722 }
 723
 724 /// Given a type, return all traits in scope in `module` implemented by that type.
 725 ///
 726 /// NOTE: this cannot be a query because more traits could be available when more crates are compiled!
 727 /// So it is not stable to serialize cross-crate.
 728 fn traits_implemented_by(cx: &mut DocContext<'_>, type_: DefId, module: DefId) -> FxHashSet<DefId> {
 729     let mut resolver = cx.resolver.borrow_mut();
 730     let in_scope_traits = cx.module_trait_cache.entry(module).or_insert_with(|| {
 731         resolver.access(|resolver| {
 732             let parent_scope = &ParentScope::module(resolver.get_module(module), resolver);
 733             resolver
 734                 .traits_in_scope(None, parent_scope, SyntaxContext::root(), None)
 735                 .into_iter()
 736                 .map(|candidate| candidate.def_id)
 737                 .collect()
 738         })
 739     });
 740
 741     let tcx = cx.tcx;
 742     let ty = tcx.type_of(type_);
 743     let iter = in_scope_traits.iter().flat_map(|&trait_| {
 744         trace!("considering explicit impl for trait {:?}", trait_);
 745
 746         // Look at each trait implementation to see if it's an impl for `did`
 747         tcx.find_map_relevant_impl(trait_, ty, |impl_| {
 748             let trait_ref = tcx.impl_trait_ref(impl_).expect("this is not an inherent impl");
 749             // Check if these are the same type.
 750             let impl_type = trait_ref.self_ty();
 751             trace!(
 752                 "comparing type {} with kind {:?} against type {:?}",
 753                 impl_type,
 754                 impl_type.kind(),
 755                 type_
 756             );
 757             // Fast path: if this is a primitive simple `==` will work
 758             let saw_impl = impl_type == ty
 759                 || match impl_type.kind() {
 760                     // Check if these are the same def_id
 761                     ty::Adt(def, _) => {
 762                         debug!("adt def_id: {:?}", def.did);
 763                         def.did == type_
 764                     }
 765                     ty::Foreign(def_id) => *def_id == type_,
 766                     _ => false,
 767                 };
 768
 769             if saw_impl { Some(trait_) } else { None }
 770         })
 771     });
 772     iter.collect()
 773 }
 774
 775 /// Check for resolve collisions between a trait and its derive.
 776 ///
 777 /// These are common and we should just resolve to the trait in that case.
 778 fn is_derive_trait_collision<T>(ns: &PerNS<Result<(Res, T), ResolutionFailure<'_>>>) -> bool {
 779     matches!(
 780         *ns,
 781         PerNS {
 782             type_ns: Ok((Res::Def(DefKind::Trait, _), _)),
 783             macro_ns: Ok((Res::Def(DefKind::Macro(MacroKind::Derive), _), _)),
 784             ..
 785         }
 786     )
 787 }
 788
 789 impl<'a, 'tcx> DocFolder for LinkCollector<'a, 'tcx> {
 790     fn fold_item(&mut self, mut item: Item) -> Option<Item> {
 791         use rustc_middle::ty::DefIdTree;
 792
 793         let parent_node = if item.is_fake() {
 794             None
 795         } else {
 796             find_nearest_parent_module(self.cx.tcx, item.def_id)
 797         };
 798
 799         if parent_node.is_some() {
 800             trace!("got parent node for {:?} {:?}, id {:?}", item.type_(), item.name, item.def_id);
 801         }
 802
 803         // find item's parent to resolve `Self` in item's docs below
 804         debug!("looking for the `Self` type");
 805         let self_id = if item.is_fake() {
 806             None
 807         // Checking if the item is a field in an enum variant
 808         } else if (matches!(self.cx.tcx.def_kind(item.def_id), DefKind::Field)
 809             && matches!(
 810                 self.cx.tcx.def_kind(self.cx.tcx.parent(item.def_id).unwrap()),
 811                 DefKind::Variant
 812             ))
 813         {
 814             self.cx.tcx.parent(item.def_id).and_then(|item_id| self.cx.tcx.parent(item_id))
 815         } else if matches!(
 816             self.cx.tcx.def_kind(item.def_id),
 817             DefKind::AssocConst
 818                 | DefKind::AssocFn
 819                 | DefKind::AssocTy
 820                 | DefKind::Variant
 821                 | DefKind::Field
 822         ) {
 823             self.cx.tcx.parent(item.def_id)
 824         // HACK(jynelson): `clean` marks associated types as `TypedefItem`, not as `AssocTypeItem`.
 825         // Fixing this breaks `fn render_deref_methods`.
 826         // As a workaround, see if the parent of the item is an `impl`; if so this must be an associated item,
 827         // regardless of what rustdoc wants to call it.
 828         } else if let Some(parent) = self.cx.tcx.parent(item.def_id) {
 829             let parent_kind = self.cx.tcx.def_kind(parent);
 830             Some(if parent_kind == DefKind::Impl { parent } else { item.def_id })
 831         } else {
 832             Some(item.def_id)
 833         };
 834
 835         // FIXME(jynelson): this shouldn't go through stringification, rustdoc should just use the DefId directly
 836         let self_name = self_id.and_then(|self_id| {
 837             if matches!(self.cx.tcx.def_kind(self_id), DefKind::Impl) {
 838                 // using `ty.to_string()` (or any variant) has issues with raw idents
 839                 let ty = self.cx.tcx.type_of(self_id);
 840                 let name = match ty.kind() {
 841                     ty::Adt(def, _) => Some(self.cx.tcx.item_name(def.did).to_string()),
 842                     other if other.is_primitive() => Some(ty.to_string()),
 843                     _ => None,
 844                 };
 845                 debug!("using type_of(): {:?}", name);
 846                 name
 847             } else {
 848                 let name = self.cx.tcx.opt_item_name(self_id).map(|sym| sym.to_string());
 849                 debug!("using item_name(): {:?}", name);
 850                 name
 851             }
 852         });
 853
 854         if item.is_mod() && item.attrs.inner_docs {
 855             self.mod_ids.push(item.def_id);
 856         }
 857
 858         // We want to resolve in the lexical scope of the documentation.
 859         // In the presence of re-exports, this is not the same as the module of the item.
 860         // Rather than merging all documentation into one, resolve it one attribute at a time
 861         // so we know which module it came from.
 862         for (parent_module, doc) in item.attrs.collapsed_doc_value_by_module_level() {
 863             debug!("combined_docs={}", doc);
 864
 865             let (krate, parent_node) = if let Some(id) = parent_module {
 866                 (id.krate, Some(id))
 867             } else {
 868                 (item.def_id.krate, parent_node)
 869             };
 870             // NOTE: if there are links that start in one crate and end in another, this will not resolve them.
 871             // This is a degenerate case and it's not supported by rustdoc.
 872             for md_link in markdown_links(&doc) {
 873                 let link = self.resolve_link(&item, &doc, &self_name, parent_node, krate, md_link);
 874                 if let Some(link) = link {
 875                     item.attrs.links.push(link);
 876                 }
 877             }
 878         }
 879
 880         Some(if item.is_mod() {
 881             if !item.attrs.inner_docs {
 882                 self.mod_ids.push(item.def_id);
 883             }
 884
 885             let ret = self.fold_item_recur(item);
 886             self.mod_ids.pop();
 887             ret
 888         } else {
 889             self.fold_item_recur(item)
 890         })
 891     }
 892 }
 893
 894 impl LinkCollector<'_, '_> {
 895     /// This is the entry point for resolving an intra-doc link.
 896     ///
 897     /// FIXME(jynelson): this is way too many arguments
 898     fn resolve_link(
 899         &mut self,
 900         item: &Item,
 901         dox: &str,
 902         self_name: &Option<String>,
 903         parent_node: Option<DefId>,
 904         krate: CrateNum,
 905         ori_link: MarkdownLink,
 906     ) -> Option<ItemLink> {
 907         trace!("considering link '{}'", ori_link.link);
 908
 909         // Bail early for real links.
 910         if ori_link.link.contains('/') {
 911             return None;
 912         }
 913
 914         // [] is mostly likely not supposed to be a link
 915         if ori_link.link.is_empty() {
 916             return None;
 917         }
 918
 919         let link = ori_link.link.replace("`", "");
 920         let no_backticks_range = range_between_backticks(&ori_link);
 921         let parts = link.split('#').collect::<Vec<_>>();
 922         let (link, extra_fragment) = if parts.len() > 2 {
 923             // A valid link can't have multiple #'s
 924             anchor_failure(
 925                 self.cx,
 926                 &item,
 927                 &link,
 928                 dox,
 929                 ori_link.range,
 930                 AnchorFailure::MultipleAnchors,
 931             );
 932             return None;
 933         } else if parts.len() == 2 {
 934             if parts[0].trim().is_empty() {
 935                 // This is an anchor to an element of the current page, nothing to do in here!
 936                 return None;
 937             }
 938             (parts[0], Some(parts[1].to_owned()))
 939         } else {
 940             (parts[0], None)
 941         };
 942
 943         // Parse and strip the disambiguator from the link, if present.
 944         let (mut path_str, disambiguator) = match Disambiguator::from_str(&link) {
 945             Ok(Some((d, path))) => (path.trim(), Some(d)),
 946             Ok(None) => (link.trim(), None),
 947             Err((err_msg, relative_range)) => {
 948                 if !should_ignore_link_with_disambiguators(link) {
 949                     // Only report error if we would not have ignored this link.
 950                     // See issue #83859.
 951                     let disambiguator_range = (no_backticks_range.start + relative_range.start)
 952                         ..(no_backticks_range.start + relative_range.end);
 953                     disambiguator_error(self.cx, &item, dox, disambiguator_range, &err_msg);
 954                 }
 955                 return None;
 956             }
 957         };
 958
 959         if should_ignore_link(path_str) {
 960             return None;
 961         }
 962
 963         // We stripped `()` and `!` when parsing the disambiguator.
 964         // Add them back to be displayed, but not prefix disambiguators.
 965         let link_text =
 966             disambiguator.map(|d| d.display_for(path_str)).unwrap_or_else(|| path_str.to_owned());
 967
 968         // In order to correctly resolve intra-doc links we need to
 969         // pick a base AST node to work from.  If the documentation for
 970         // this module came from an inner comment (//!) then we anchor
 971         // our name resolution *inside* the module.  If, on the other
 972         // hand it was an outer comment (///) then we anchor the name
 973         // resolution in the parent module on the basis that the names
 974         // used are more likely to be intended to be parent names.  For
 975         // this, we set base_node to None for inner comments since
 976         // we've already pushed this node onto the resolution stack but
 977         // for outer comments we explicitly try and resolve against the
 978         // parent_node first.
 979         let base_node = if item.is_mod() && item.attrs.inner_docs {
 980             self.mod_ids.last().copied()
 981         } else {
 982             parent_node
 983         };
 984
 985         let mut module_id = if let Some(id) = base_node {
 986             id
 987         } else {
 988             // This is a bug.
 989             debug!("attempting to resolve item without parent module: {}", path_str);
 990             resolution_failure(
 991                 self,
 992                 &item,
 993                 path_str,
 994                 disambiguator,
 995                 dox,
 996                 ori_link.range,
 997                 smallvec![ResolutionFailure::NoParentItem],
 998             );
 999             return None;
1000         };
1001
1002         let resolved_self;
1003         // replace `Self` with suitable item's parent name
1004         let is_lone_self = path_str == "Self";
1005         let is_lone_crate = path_str == "crate";
1006         if path_str.starts_with("Self::") || is_lone_self {
1007             if let Some(ref name) = self_name {
1008                 if is_lone_self {
1009                     path_str = name;
1010                 } else {
1011                     resolved_self = format!("{}::{}", name, &path_str[6..]);
1012                     path_str = &resolved_self;
1013                 }
1014             }
1015         } else if path_str.starts_with("crate::") || is_lone_crate {
1016             use rustc_span::def_id::CRATE_DEF_INDEX;
1017
1018             // HACK(jynelson): rustc_resolve thinks that `crate` is the crate currently being documented.
1019             // But rustdoc wants it to mean the crate this item was originally present in.
1020             // To work around this, remove it and resolve relative to the crate root instead.
1021             // HACK(jynelson)(2): If we just strip `crate::` then suddenly primitives become ambiguous
1022             // (consider `crate::char`). Instead, change it to `self::`. This works because 'self' is now the crate root.
1023             // FIXME(#78696): This doesn't always work.
1024             if is_lone_crate {
1025                 path_str = "self";
1026             } else {
1027                 resolved_self = format!("self::{}", &path_str["crate::".len()..]);
1028                 path_str = &resolved_self;
1029             }
1030             module_id = DefId { krate, index: CRATE_DEF_INDEX };
1031         }
1032
1033         // Strip generics from the path.
1034         let stripped_path_string;
1035         if path_str.contains(['<', '>'].as_slice()) {
1036             stripped_path_string = match strip_generics_from_path(path_str) {
1037                 Ok(path) => path,
1038                 Err(err_kind) => {
1039                     debug!("link has malformed generics: {}", path_str);
1040                     resolution_failure(
1041                         self,
1042                         &item,
1043                         path_str,
1044                         disambiguator,
1045                         dox,
1046                         ori_link.range,
1047                         smallvec![err_kind],
1048                     );
1049                     return None;
1050                 }
1051             };
1052             path_str = &stripped_path_string;
1053         }
1054         // Sanity check to make sure we don't have any angle brackets after stripping generics.
1055         assert!(!path_str.contains(['<', '>'].as_slice()));
1056
1057         // The link is not an intra-doc link if it still contains spaces after stripping generics.
1058         if path_str.contains(' ') {
1059             return None;
1060         }
1061
1062         let diag_info = DiagnosticInfo {
1063             item,
1064             dox,
1065             ori_link: &ori_link.link,
1066             link_range: ori_link.range.clone(),
1067         };
1068         let (mut res, mut fragment) = self.resolve_with_disambiguator_cached(
1069             ResolutionInfo {
1070                 module_id,
1071                 dis: disambiguator,
1072                 path_str: path_str.to_owned(),
1073                 extra_fragment,
1074             },
1075             diag_info,
1076             matches!(ori_link.kind, LinkType::Reference | LinkType::Shortcut),
1077         )?;
1078
1079         // Check for a primitive which might conflict with a module
1080         // Report the ambiguity and require that the user specify which one they meant.
1081         // FIXME: could there ever be a primitive not in the type namespace?
1082         if matches!(
1083             disambiguator,
1084             None | Some(Disambiguator::Namespace(Namespace::TypeNS) | Disambiguator::Primitive)
1085         ) && !matches!(res, Res::Primitive(_))
1086         {
1087             if let Some(prim) = resolve_primitive(path_str, TypeNS) {
1088                 // `prim@char`
1089                 if matches!(disambiguator, Some(Disambiguator::Primitive)) {
1090                     if fragment.is_some() {
1091                         anchor_failure(
1092                             self.cx,
1093                             &item,
1094                             path_str,
1095                             dox,
1096                             ori_link.range,
1097                             AnchorFailure::RustdocAnchorConflict(prim),
1098                         );
1099                         return None;
1100                     }
1101                     res = prim;
1102                     fragment = Some(prim.name(self.cx.tcx));
1103                 } else {
1104                     // `[char]` when a `char` module is in scope
1105                     let candidates = vec![res, prim];
1106                     ambiguity_error(self.cx, &item, path_str, dox, ori_link.range, candidates);
1107                     return None;
1108                 }
1109             }
1110         }
1111
1112         let report_mismatch = |specified: Disambiguator, resolved: Disambiguator| {
1113             // The resolved item did not match the disambiguator; give a better error than 'not found'
1114             let msg = format!("incompatible link kind for `{}`", path_str);
1115             let callback = |diag: &mut DiagnosticBuilder<'_>, sp| {
1116                 let note = format!(
1117                     "this link resolved to {} {}, which is not {} {}",
1118                     resolved.article(),
1119                     resolved.descr(),
1120                     specified.article(),
1121                     specified.descr()
1122                 );
1123                 diag.note(&note);
1124                 suggest_disambiguator(resolved, diag, path_str, dox, sp, &ori_link.range);
1125             };
1126             report_diagnostic(
1127                 self.cx.tcx,
1128                 BROKEN_INTRA_DOC_LINKS,
1129                 &msg,
1130                 &item,
1131                 dox,
1132                 &ori_link.range,
1133                 callback,
1134             );
1135         };
1136
1137         let verify = |kind: DefKind, id: DefId| {
1138             let (kind, id) = self.kind_side_channel.take().unwrap_or((kind, id));
1139             debug!("intra-doc link to {} resolved to {:?} (id: {:?})", path_str, res, id);
1140
1141             // Disallow e.g. linking to enums with `struct@`
1142             debug!("saw kind {:?} with disambiguator {:?}", kind, disambiguator);
1143             match (kind, disambiguator) {
1144                 | (DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst, Some(Disambiguator::Kind(DefKind::Const)))
1145                 // NOTE: this allows 'method' to mean both normal functions and associated functions
1146                 // This can't cause ambiguity because both are in the same namespace.
1147                 | (DefKind::Fn | DefKind::AssocFn, Some(Disambiguator::Kind(DefKind::Fn)))
1148                 // These are namespaces; allow anything in the namespace to match
1149                 | (_, Some(Disambiguator::Namespace(_)))
1150                 // If no disambiguator given, allow anything
1151                 | (_, None)
1152                 // All of these are valid, so do nothing
1153                 => {}
1154                 (actual, Some(Disambiguator::Kind(expected))) if actual == expected => {}
1155                 (_, Some(specified @ Disambiguator::Kind(_) | specified @ Disambiguator::Primitive)) => {
1156                     report_mismatch(specified, Disambiguator::Kind(kind));
1157                     return None;
1158                 }
1159             }
1160
1161             // item can be non-local e.g. when using #[doc(primitive = "pointer")]
1162             if let Some((src_id, dst_id)) = id
1163                 .as_local()
1164                 .and_then(|dst_id| item.def_id.as_local().map(|src_id| (src_id, dst_id)))
1165             {
1166                 use rustc_hir::def_id::LOCAL_CRATE;
1167
1168                 let hir_src = self.cx.tcx.hir().local_def_id_to_hir_id(src_id);
1169                 let hir_dst = self.cx.tcx.hir().local_def_id_to_hir_id(dst_id);
1170
1171                 if self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_src)
1172                     && !self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_dst)
1173                 {
1174                     privacy_error(self.cx, &item, &path_str, dox, &ori_link);
1175                 }
1176             }
1177
1178             Some(())
1179         };
1180
1181         match res {
1182             Res::Primitive(prim) => {
1183                 if let Some((kind, id)) = self.kind_side_channel.take() {
1184                     // We're actually resolving an associated item of a primitive, so we need to
1185                     // verify the disambiguator (if any) matches the type of the associated item.
1186                     // This case should really follow the same flow as the `Res::Def` branch below,
1187                     // but attempting to add a call to `clean::register_res` causes an ICE. @jyn514
1188                     // thinks `register_res` is only needed for cross-crate re-exports, but Rust
1189                     // doesn't allow statements like `use str::trim;`, making this a (hopefully)
1190                     // valid omission. See https://github.com/rust-lang/rust/pull/80660#discussion_r551585677
1191                     // for discussion on the matter.
1192                     verify(kind, id)?;
1193
1194                     // FIXME: it would be nice to check that the feature gate was enabled in the original crate, not just ignore it altogether.
1195                     // However I'm not sure how to check that across crates.
1196                     if prim == PrimitiveType::RawPointer
1197                         && item.def_id.is_local()
1198                         && !self.cx.tcx.features().intra_doc_pointers
1199                     {
1200                         let span = super::source_span_for_markdown_range(
1201                             self.cx.tcx,
1202                             dox,
1203                             &ori_link.range,
1204                             &item.attrs,
1205                         )
1206                         .unwrap_or_else(|| span_of_attrs(&item.attrs).unwrap_or(item.span.inner()));
1207
1208                         rustc_session::parse::feature_err(
1209                             &self.cx.tcx.sess.parse_sess,
1210                             sym::intra_doc_pointers,
1211                             span,
1212                             "linking to associated items of raw pointers is experimental",
1213                         )
1214                         .note("rustdoc does not allow disambiguating between `*const` and `*mut`, and pointers are unstable until it does")
1215                         .emit();
1216                     }
1217                 } else {
1218                     match disambiguator {
1219                         Some(Disambiguator::Primitive | Disambiguator::Namespace(_)) | None => {}
1220                         Some(other) => {
1221                             report_mismatch(other, Disambiguator::Primitive);
1222                             return None;
1223                         }
1224                     }
1225                 }
1226
1227                 Some(ItemLink { link: ori_link.link, link_text, did: None, fragment })
1228             }
1229             Res::Def(kind, id) => {
1230                 verify(kind, id)?;
1231                 let id = clean::register_res(self.cx, rustc_hir::def::Res::Def(kind, id));
1232                 Some(ItemLink { link: ori_link.link, link_text, did: Some(id), fragment })
1233             }
1234         }
1235     }
1236
1237     fn resolve_with_disambiguator_cached(
1238         &mut self,
1239         key: ResolutionInfo,
1240         diag: DiagnosticInfo<'_>,
1241         cache_resolution_failure: bool,
1242     ) -> Option<(Res, Option<String>)> {
1243         // Try to look up both the result and the corresponding side channel value
1244         if let Some(ref cached) = self.visited_links.get(&key) {
1245             match cached {
1246                 Some(cached) => {
1247                     self.kind_side_channel.set(cached.side_channel.clone());
1248                     return Some(cached.res.clone());
1249                 }
1250                 None if cache_resolution_failure => return None,
1251                 None => {
1252                     // Although we hit the cache and found a resolution error, this link isn't
1253                     // supposed to cache those. Run link resolution again to emit the expected
1254                     // resolution error.
1255                 }
1256             }
1257         }
1258
1259         let res = self.resolve_with_disambiguator(&key, diag);
1260
1261         // Cache only if resolved successfully - don't silence duplicate errors
1262         if let Some(res) = res {
1263             // Store result for the actual namespace
1264             self.visited_links.insert(
1265                 key,
1266                 Some(CachedLink {
1267                     res: res.clone(),
1268                     side_channel: self.kind_side_channel.clone().into_inner(),
1269                 }),
1270             );
1271
1272             Some(res)
1273         } else {
1274             if cache_resolution_failure {
1275                 // For reference-style links we only want to report one resolution error
1276                 // so let's cache them as well.
1277                 self.visited_links.insert(key, None);
1278             }
1279
1280             None
1281         }
1282     }
1283
1284     /// After parsing the disambiguator, resolve the main part of the link.
1285     // FIXME(jynelson): wow this is just so much
1286     fn resolve_with_disambiguator(
1287         &mut self,
1288         key: &ResolutionInfo,
1289         diag: DiagnosticInfo<'_>,
1290     ) -> Option<(Res, Option<String>)> {
1291         let disambiguator = key.dis;
1292         let path_str = &key.path_str;
1293         let base_node = key.module_id;
1294         let extra_fragment = &key.extra_fragment;
1295
1296         match disambiguator.map(Disambiguator::ns) {
1297             Some(expected_ns @ (ValueNS | TypeNS)) => {
1298                 match self.resolve(path_str, expected_ns, base_node, extra_fragment) {
1299                     Ok(res) => Some(res),
1300                     Err(ErrorKind::Resolve(box mut kind)) => {
1301                         // We only looked in one namespace. Try to give a better error if possible.
1302                         if kind.full_res().is_none() {
1303                             let other_ns = if expected_ns == ValueNS { TypeNS } else { ValueNS };
1304                             // FIXME: really it should be `resolution_failure` that does this, not `resolve_with_disambiguator`
1305                             // See https://github.com/rust-lang/rust/pull/76955#discussion_r493953382 for a good approach
1306                             for &new_ns in &[other_ns, MacroNS] {
1307                                 if let Some(res) =
1308                                     self.check_full_res(new_ns, path_str, base_node, extra_fragment)
1309                                 {
1310                                     kind = ResolutionFailure::WrongNamespace { res, expected_ns };
1311                                     break;
1312                                 }
1313                             }
1314                         }
1315                         resolution_failure(
1316                             self,
1317                             diag.item,
1318                             path_str,
1319                             disambiguator,
1320                             diag.dox,
1321                             diag.link_range,
1322                             smallvec![kind],
1323                         );
1324                         // This could just be a normal link or a broken link
1325                         // we could potentially check if something is
1326                         // "intra-doc-link-like" and warn in that case.
1327                         None
1328                     }
1329                     Err(ErrorKind::AnchorFailure(msg)) => {
1330                         anchor_failure(
1331                             self.cx,
1332                             diag.item,
1333                             diag.ori_link,
1334                             diag.dox,
1335                             diag.link_range,
1336                             msg,
1337                         );
1338                         None
1339                     }
1340                 }
1341             }
1342             None => {
1343                 // Try everything!
1344                 let mut candidates = PerNS {
1345                     macro_ns: self
1346                         .resolve_macro(path_str, base_node)
1347                         .map(|res| (res, extra_fragment.clone())),
1348                     type_ns: match self.resolve(path_str, TypeNS, base_node, extra_fragment) {
1349                         Ok(res) => {
1350                             debug!("got res in TypeNS: {:?}", res);
1351                             Ok(res)
1352                         }
1353                         Err(ErrorKind::AnchorFailure(msg)) => {
1354                             anchor_failure(
1355                                 self.cx,
1356                                 diag.item,
1357                                 diag.ori_link,
1358                                 diag.dox,
1359                                 diag.link_range,
1360                                 msg,
1361                             );
1362                             return None;
1363                         }
1364                         Err(ErrorKind::Resolve(box kind)) => Err(kind),
1365                     },
1366                     value_ns: match self.resolve(path_str, ValueNS, base_node, extra_fragment) {
1367                         Ok(res) => Ok(res),
1368                         Err(ErrorKind::AnchorFailure(msg)) => {
1369                             anchor_failure(
1370                                 self.cx,
1371                                 diag.item,
1372                                 diag.ori_link,
1373                                 diag.dox,
1374                                 diag.link_range,
1375                                 msg,
1376                             );
1377                             return None;
1378                         }
1379                         Err(ErrorKind::Resolve(box kind)) => Err(kind),
1380                     }
1381                     .and_then(|(res, fragment)| {
1382                         // Constructors are picked up in the type namespace.
1383                         match res {
1384                             Res::Def(DefKind::Ctor(..), _) => {
1385                                 Err(ResolutionFailure::WrongNamespace { res, expected_ns: TypeNS })
1386                             }
1387                             _ => {
1388                                 match (fragment, extra_fragment.clone()) {
1389                                     (Some(fragment), Some(_)) => {
1390                                         // Shouldn't happen but who knows?
1391                                         Ok((res, Some(fragment)))
1392                                     }
1393                                     (fragment, None) | (None, fragment) => Ok((res, fragment)),
1394                                 }
1395                             }
1396                         }
1397                     }),
1398                 };
1399
1400                 let len = candidates.iter().filter(|res| res.is_ok()).count();
1401
1402                 if len == 0 {
1403                     resolution_failure(
1404                         self,
1405                         diag.item,
1406                         path_str,
1407                         disambiguator,
1408                         diag.dox,
1409                         diag.link_range,
1410                         candidates.into_iter().filter_map(|res| res.err()).collect(),
1411                     );
1412                     // this could just be a normal link
1413                     return None;
1414                 }
1415
1416                 if len == 1 {
1417                     Some(candidates.into_iter().filter_map(|res| res.ok()).next().unwrap())
1418                 } else if len == 2 && is_derive_trait_collision(&candidates) {
1419                     Some(candidates.type_ns.unwrap())
1420                 } else {
1421                     if is_derive_trait_collision(&candidates) {
1422                         candidates.macro_ns = Err(ResolutionFailure::Dummy);
1423                     }
1424                     // If we're reporting an ambiguity, don't mention the namespaces that failed
1425                     let candidates = candidates.map(|candidate| candidate.ok().map(|(res, _)| res));
1426                     ambiguity_error(
1427                         self.cx,
1428                         diag.item,
1429                         path_str,
1430                         diag.dox,
1431                         diag.link_range,
1432                         candidates.present_items().collect(),
1433                     );
1434                     None
1435                 }
1436             }
1437             Some(MacroNS) => {
1438                 match self.resolve_macro(path_str, base_node) {
1439                     Ok(res) => Some((res, extra_fragment.clone())),
1440                     Err(mut kind) => {
1441                         // `resolve_macro` only looks in the macro namespace. Try to give a better error if possible.
1442                         for &ns in &[TypeNS, ValueNS] {
1443                             if let Some(res) =
1444                                 self.check_full_res(ns, path_str, base_node, extra_fragment)
1445                             {
1446                                 kind =
1447                                     ResolutionFailure::WrongNamespace { res, expected_ns: MacroNS };
1448                                 break;
1449                             }
1450                         }
1451                         resolution_failure(
1452                             self,
1453                             diag.item,
1454                             path_str,
1455                             disambiguator,
1456                             diag.dox,
1457                             diag.link_range,
1458                             smallvec![kind],
1459                         );
1460                         None
1461                     }
1462                 }
1463             }
1464         }
1465     }
1466 }
1467
1468 /// Get the section of a link between the backticks,
1469 /// or the whole link if there aren't any backticks.
1470 ///
1471 /// For example:
1472 ///
1473 /// ```text
1474 /// [`Foo`]
1475 ///   ^^^
1476 /// ```
1477 fn range_between_backticks(ori_link: &MarkdownLink) -> Range<usize> {
1478     let after_first_backtick_group = ori_link.link.bytes().position(|b| b != b'`').unwrap_or(0);
1479     let before_second_backtick_group = ori_link
1480         .link
1481         .bytes()
1482         .skip(after_first_backtick_group)
1483         .position(|b| b == b'`')
1484         .unwrap_or(ori_link.link.len());
1485     (ori_link.range.start + after_first_backtick_group)
1486         ..(ori_link.range.start + before_second_backtick_group)
1487 }
1488
1489 /// Returns true if we should ignore `link` due to it being unlikely
1490 /// that it is an intra-doc link. `link` should still have disambiguators
1491 /// if there were any.
1492 ///
1493 /// The difference between this and [`should_ignore_link()`] is that this
1494 /// check should only be used on links that still have disambiguators.
1495 fn should_ignore_link_with_disambiguators(link: &str) -> bool {
1496     link.contains(|ch: char| !(ch.is_alphanumeric() || ":_<>, !*&;@()".contains(ch)))
1497 }
1498
1499 /// Returns true if we should ignore `path_str` due to it being unlikely
1500 /// that it is an intra-doc link.
1501 fn should_ignore_link(path_str: &str) -> bool {
1502     path_str.contains(|ch: char| !(ch.is_alphanumeric() || ":_<>, !*&;".contains(ch)))
1503 }
1504
1505 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1506 /// Disambiguators for a link.
1507 crate enum Disambiguator {
1508     /// `prim@`
1509     ///
1510     /// This is buggy, see <https://github.com/rust-lang/rust/pull/77875#discussion_r503583103>
1511     Primitive,
1512     /// `struct@` or `f()`
1513     Kind(DefKind),
1514     /// `type@`
1515     Namespace(Namespace),
1516 }
1517
1518 impl Disambiguator {
1519     /// The text that should be displayed when the path is rendered as HTML.
1520     ///
1521     /// NOTE: `path` is not the original link given by the user, but a name suitable for passing to `resolve`.
1522     fn display_for(&self, path: &str) -> String {
1523         match self {
1524             // FIXME: this will have different output if the user had `m!()` originally.
1525             Self::Kind(DefKind::Macro(MacroKind::Bang)) => format!("{}!", path),
1526             Self::Kind(DefKind::Fn) => format!("{}()", path),
1527             _ => path.to_owned(),
1528         }
1529     }
1530
1531     /// Given a link, parse and return `(disambiguator, path_str)`.
1532     ///
1533     /// This returns `Ok(Some(...))` if a disambiguator was found,
1534     /// `Ok(None)` if no disambiguator was found, or `Err(...)`
1535     /// if there was a problem with the disambiguator.
1536     crate fn from_str(link: &str) -> Result<Option<(Self, &str)>, (String, Range<usize>)> {
1537         use Disambiguator::{Kind, Namespace as NS, Primitive};
1538
1539         if let Some(idx) = link.find('@') {
1540             let (prefix, rest) = link.split_at(idx);
1541             let d = match prefix {
1542                 "struct" => Kind(DefKind::Struct),
1543                 "enum" => Kind(DefKind::Enum),
1544                 "trait" => Kind(DefKind::Trait),
1545                 "union" => Kind(DefKind::Union),
1546                 "module" | "mod" => Kind(DefKind::Mod),
1547                 "const" | "constant" => Kind(DefKind::Const),
1548                 "static" => Kind(DefKind::Static),
1549                 "function" | "fn" | "method" => Kind(DefKind::Fn),
1550                 "derive" => Kind(DefKind::Macro(MacroKind::Derive)),
1551                 "type" => NS(Namespace::TypeNS),
1552                 "value" => NS(Namespace::ValueNS),
1553                 "macro" => NS(Namespace::MacroNS),
1554                 "prim" | "primitive" => Primitive,
1555                 _ => return Err((format!("unknown disambiguator `{}`", prefix), 0..idx)),
1556             };
1557             Ok(Some((d, &rest[1..])))
1558         } else {
1559             let suffixes = [
1560                 ("!()", DefKind::Macro(MacroKind::Bang)),
1561                 ("()", DefKind::Fn),
1562                 ("!", DefKind::Macro(MacroKind::Bang)),
1563             ];
1564             for &(suffix, kind) in &suffixes {
1565                 if let Some(link) = link.strip_suffix(suffix) {
1566                     // Avoid turning `!` or `()` into an empty string
1567                     if !link.is_empty() {
1568                         return Ok(Some((Kind(kind), link)));
1569                     }
1570                 }
1571             }
1572             Ok(None)
1573         }
1574     }
1575
1576     fn from_res(res: Res) -> Self {
1577         match res {
1578             Res::Def(kind, _) => Disambiguator::Kind(kind),
1579             Res::Primitive(_) => Disambiguator::Primitive,
1580         }
1581     }
1582
1583     /// Used for error reporting.
1584     fn suggestion(self) -> Suggestion {
1585         let kind = match self {
1586             Disambiguator::Primitive => return Suggestion::Prefix("prim"),
1587             Disambiguator::Kind(kind) => kind,
1588             Disambiguator::Namespace(_) => panic!("display_for cannot be used on namespaces"),
1589         };
1590         if kind == DefKind::Macro(MacroKind::Bang) {
1591             return Suggestion::Macro;
1592         } else if kind == DefKind::Fn || kind == DefKind::AssocFn {
1593             return Suggestion::Function;
1594         }
1595
1596         let prefix = match kind {
1597             DefKind::Struct => "struct",
1598             DefKind::Enum => "enum",
1599             DefKind::Trait => "trait",
1600             DefKind::Union => "union",
1601             DefKind::Mod => "mod",
1602             DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst => {
1603                 "const"
1604             }
1605             DefKind::Static => "static",
1606             DefKind::Macro(MacroKind::Derive) => "derive",
1607             // Now handle things that don't have a specific disambiguator
1608             _ => match kind
1609                 .ns()
1610                 .expect("tried to calculate a disambiguator for a def without a namespace?")
1611             {
1612                 Namespace::TypeNS => "type",
1613                 Namespace::ValueNS => "value",
1614                 Namespace::MacroNS => "macro",
1615             },
1616         };
1617
1618         Suggestion::Prefix(prefix)
1619     }
1620
1621     fn ns(self) -> Namespace {
1622         match self {
1623             Self::Namespace(n) => n,
1624             Self::Kind(k) => {
1625                 k.ns().expect("only DefKinds with a valid namespace can be disambiguators")
1626             }
1627             Self::Primitive => TypeNS,
1628         }
1629     }
1630
1631     fn article(self) -> &'static str {
1632         match self {
1633             Self::Namespace(_) => panic!("article() doesn't make sense for namespaces"),
1634             Self::Kind(k) => k.article(),
1635             Self::Primitive => "a",
1636         }
1637     }
1638
1639     fn descr(self) -> &'static str {
1640         match self {
1641             Self::Namespace(n) => n.descr(),
1642             // HACK(jynelson): by looking at the source I saw the DefId we pass
1643             // for `expected.descr()` doesn't matter, since it's not a crate
1644             Self::Kind(k) => k.descr(DefId::local(hir::def_id::DefIndex::from_usize(0))),
1645             Self::Primitive => "builtin type",
1646         }
1647     }
1648 }
1649
1650 /// A suggestion to show in a diagnostic.
1651 enum Suggestion {
1652     /// `struct@`
1653     Prefix(&'static str),
1654     /// `f()`
1655     Function,
1656     /// `m!`
1657     Macro,
1658 }
1659
1660 impl Suggestion {
1661     fn descr(&self) -> Cow<'static, str> {
1662         match self {
1663             Self::Prefix(x) => format!("prefix with `{}@`", x).into(),
1664             Self::Function => "add parentheses".into(),
1665             Self::Macro => "add an exclamation mark".into(),
1666         }
1667     }
1668
1669     fn as_help(&self, path_str: &str) -> String {
1670         // FIXME: if this is an implied shortcut link, it's bad style to suggest `@`
1671         match self {
1672             Self::Prefix(prefix) => format!("{}@{}", prefix, path_str),
1673             Self::Function => format!("{}()", path_str),
1674             Self::Macro => format!("{}!", path_str),
1675         }
1676     }
1677 }
1678
1679 /// Reports a diagnostic for an intra-doc link.
1680 ///
1681 /// If no link range is provided, or the source span of the link cannot be determined, the span of
1682 /// the entire documentation block is used for the lint. If a range is provided but the span
1683 /// calculation fails, a note is added to the diagnostic pointing to the link in the markdown.
1684 ///
1685 /// The `decorate` callback is invoked in all cases to allow further customization of the
1686 /// diagnostic before emission. If the span of the link was able to be determined, the second
1687 /// parameter of the callback will contain it, and the primary span of the diagnostic will be set
1688 /// to it.
1689 fn report_diagnostic(
1690     tcx: TyCtxt<'_>,
1691     lint: &'static Lint,
1692     msg: &str,
1693     item: &Item,
1694     dox: &str,
1695     link_range: &Range<usize>,
1696     decorate: impl FnOnce(&mut DiagnosticBuilder<'_>, Option<rustc_span::Span>),
1697 ) {
1698     let hir_id = match DocContext::as_local_hir_id(tcx, item.def_id) {
1699         Some(hir_id) => hir_id,
1700         None => {
1701             // If non-local, no need to check anything.
1702             info!("ignoring warning from parent crate: {}", msg);
1703             return;
1704         }
1705     };
1706
1707     let attrs = &item.attrs;
1708     let sp = span_of_attrs(attrs).unwrap_or(item.span.inner());
1709
1710     tcx.struct_span_lint_hir(lint, hir_id, sp, |lint| {
1711         let mut diag = lint.build(msg);
1712
1713         let span = super::source_span_for_markdown_range(tcx, dox, link_range, attrs);
1714
1715         if let Some(sp) = span {
1716             diag.set_span(sp);
1717         } else {
1718             // blah blah blah\nblah\nblah [blah] blah blah\nblah blah
1719             //                       ^     ~~~~
1720             //                       |     link_range
1721             //                       last_new_line_offset
1722             let last_new_line_offset = dox[..link_range.start].rfind('\n').map_or(0, |n| n + 1);
1723             let line = dox[last_new_line_offset..].lines().next().unwrap_or("");
1724
1725             // Print the line containing the `link_range` and manually mark it with '^'s.
1726             diag.note(&format!(
1727                 "the link appears in this line:\n\n{line}\n\
1728                      {indicator: <before$}{indicator:^<found$}",
1729                 line = line,
1730                 indicator = "",
1731                 before = link_range.start - last_new_line_offset,
1732                 found = link_range.len(),
1733             ));
1734         }
1735
1736         decorate(&mut diag, span);
1737
1738         diag.emit();
1739     });
1740 }
1741
1742 /// Reports a link that failed to resolve.
1743 ///
1744 /// This also tries to resolve any intermediate path segments that weren't
1745 /// handled earlier. For example, if passed `Item::Crate(std)` and `path_str`
1746 /// `std::io::Error::x`, this will resolve `std::io::Error`.
1747 fn resolution_failure(
1748     collector: &mut LinkCollector<'_, '_>,
1749     item: &Item,
1750     path_str: &str,
1751     disambiguator: Option<Disambiguator>,
1752     dox: &str,
1753     link_range: Range<usize>,
1754     kinds: SmallVec<[ResolutionFailure<'_>; 3]>,
1755 ) {
1756     let tcx = collector.cx.tcx;
1757     report_diagnostic(
1758         tcx,
1759         BROKEN_INTRA_DOC_LINKS,
1760         &format!("unresolved link to `{}`", path_str),
1761         item,
1762         dox,
1763         &link_range,
1764         |diag, sp| {
1765             let item = |res: Res| format!("the {} `{}`", res.descr(), res.name(tcx),);
1766             let assoc_item_not_allowed = |res: Res| {
1767                 let name = res.name(tcx);
1768                 format!(
1769                     "`{}` is {} {}, not a module or type, and cannot have associated items",
1770                     name,
1771                     res.article(),
1772                     res.descr()
1773                 )
1774             };
1775             // ignore duplicates
1776             let mut variants_seen = SmallVec::<[_; 3]>::new();
1777             for mut failure in kinds {
1778                 let variant = std::mem::discriminant(&failure);
1779                 if variants_seen.contains(&variant) {
1780                     continue;
1781                 }
1782                 variants_seen.push(variant);
1783
1784                 if let ResolutionFailure::NotResolved { module_id, partial_res, unresolved } =
1785                     &mut failure
1786                 {
1787                     use DefKind::*;
1788
1789                     let module_id = *module_id;
1790                     // FIXME(jynelson): this might conflict with my `Self` fix in #76467
1791                     // FIXME: maybe use itertools `collect_tuple` instead?
1792                     fn split(path: &str) -> Option<(&str, &str)> {
1793                         let mut splitter = path.rsplitn(2, "::");
1794                         splitter.next().and_then(|right| splitter.next().map(|left| (left, right)))
1795                     }
1796
1797                     // Check if _any_ parent of the path gets resolved.
1798                     // If so, report it and say the first which failed; if not, say the first path segment didn't resolve.
1799                     let mut name = path_str;
1800                     'outer: loop {
1801                         let (start, end) = if let Some(x) = split(name) {
1802                             x
1803                         } else {
1804                             // avoid bug that marked [Quux::Z] as missing Z, not Quux
1805                             if partial_res.is_none() {
1806                                 *unresolved = name.into();
1807                             }
1808                             break;
1809                         };
1810                         name = start;
1811                         for &ns in &[TypeNS, ValueNS, MacroNS] {
1812                             if let Some(res) =
1813                                 collector.check_full_res(ns, &start, module_id, &None)
1814                             {
1815                                 debug!("found partial_res={:?}", res);
1816                                 *partial_res = Some(res);
1817                                 *unresolved = end.into();
1818                                 break 'outer;
1819                             }
1820                         }
1821                         *unresolved = end.into();
1822                     }
1823
1824                     let last_found_module = match *partial_res {
1825                         Some(Res::Def(DefKind::Mod, id)) => Some(id),
1826                         None => Some(module_id),
1827                         _ => None,
1828                     };
1829                     // See if this was a module: `[path]` or `[std::io::nope]`
1830                     if let Some(module) = last_found_module {
1831                         let note = if partial_res.is_some() {
1832                             // Part of the link resolved; e.g. `std::io::nonexistent`
1833                             let module_name = tcx.item_name(module);
1834                             format!("no item named `{}` in module `{}`", unresolved, module_name)
1835                         } else {
1836                             // None of the link resolved; e.g. `Notimported`
1837                             format!("no item named `{}` in scope", unresolved)
1838                         };
1839                         if let Some(span) = sp {
1840                             diag.span_label(span, &note);
1841                         } else {
1842                             diag.note(&note);
1843                         }
1844
1845                         // If the link has `::` in it, assume it was meant to be an intra-doc link.
1846                         // Otherwise, the `[]` might be unrelated.
1847                         // FIXME: don't show this for autolinks (`<>`), `()` style links, or reference links
1848                         if !path_str.contains("::") {
1849                             diag.help(r#"to escape `[` and `]` characters, add '\' before them like `\[` or `\]`"#);
1850                         }
1851
1852                         continue;
1853                     }
1854
1855                     // Otherwise, it must be an associated item or variant
1856                     let res = partial_res.expect("None case was handled by `last_found_module`");
1857                     let name = res.name(tcx);
1858                     let kind = match res {
1859                         Res::Def(kind, _) => Some(kind),
1860                         Res::Primitive(_) => None,
1861                     };
1862                     let path_description = if let Some(kind) = kind {
1863                         match kind {
1864                             Mod | ForeignMod => "inner item",
1865                             Struct => "field or associated item",
1866                             Enum | Union => "variant or associated item",
1867                             Variant
1868                             | Field
1869                             | Closure
1870                             | Generator
1871                             | AssocTy
1872                             | AssocConst
1873                             | AssocFn
1874                             | Fn
1875                             | Macro(_)
1876                             | Const
1877                             | ConstParam
1878                             | ExternCrate
1879                             | Use
1880                             | LifetimeParam
1881                             | Ctor(_, _)
1882                             | AnonConst => {
1883                                 let note = assoc_item_not_allowed(res);
1884                                 if let Some(span) = sp {
1885                                     diag.span_label(span, &note);
1886                                 } else {
1887                                     diag.note(&note);
1888                                 }
1889                                 return;
1890                             }
1891                             Trait | TyAlias | ForeignTy | OpaqueTy | TraitAlias | TyParam
1892                             | Static => "associated item",
1893                             Impl | GlobalAsm => unreachable!("not a path"),
1894                         }
1895                     } else {
1896                         "associated item"
1897                     };
1898                     let note = format!(
1899                         "the {} `{}` has no {} named `{}`",
1900                         res.descr(),
1901                         name,
1902                         disambiguator.map_or(path_description, |d| d.descr()),
1903                         unresolved,
1904                     );
1905                     if let Some(span) = sp {
1906                         diag.span_label(span, &note);
1907                     } else {
1908                         diag.note(&note);
1909                     }
1910
1911                     continue;
1912                 }
1913                 let note = match failure {
1914                     ResolutionFailure::NotResolved { .. } => unreachable!("handled above"),
1915                     ResolutionFailure::Dummy => continue,
1916                     ResolutionFailure::WrongNamespace { res, expected_ns } => {
1917                         if let Res::Def(kind, _) = res {
1918                             let disambiguator = Disambiguator::Kind(kind);
1919                             suggest_disambiguator(
1920                                 disambiguator,
1921                                 diag,
1922                                 path_str,
1923                                 dox,
1924                                 sp,
1925                                 &link_range,
1926                             )
1927                         }
1928
1929                         format!(
1930                             "this link resolves to {}, which is not in the {} namespace",
1931                             item(res),
1932                             expected_ns.descr()
1933                         )
1934                     }
1935                     ResolutionFailure::NoParentItem => {
1936                         diag.level = rustc_errors::Level::Bug;
1937                         "all intra-doc links should have a parent item".to_owned()
1938                     }
1939                     ResolutionFailure::MalformedGenerics(variant) => match variant {
1940                         MalformedGenerics::UnbalancedAngleBrackets => {
1941                             String::from("unbalanced angle brackets")
1942                         }
1943                         MalformedGenerics::MissingType => {
1944                             String::from("missing type for generic parameters")
1945                         }
1946                         MalformedGenerics::HasFullyQualifiedSyntax => {
1947                             diag.note("see https://github.com/rust-lang/rust/issues/74563 for more information");
1948                             String::from("fully-qualified syntax is unsupported")
1949                         }
1950                         MalformedGenerics::InvalidPathSeparator => {
1951                             String::from("has invalid path separator")
1952                         }
1953                         MalformedGenerics::TooManyAngleBrackets => {
1954                             String::from("too many angle brackets")
1955                         }
1956                         MalformedGenerics::EmptyAngleBrackets => {
1957                             String::from("empty angle brackets")
1958                         }
1959                     },
1960                 };
1961                 if let Some(span) = sp {
1962                     diag.span_label(span, &note);
1963                 } else {
1964                     diag.note(&note);
1965                 }
1966             }
1967         },
1968     );
1969 }
1970
1971 /// Report an anchor failure.
1972 fn anchor_failure(
1973     cx: &DocContext<'_>,
1974     item: &Item,
1975     path_str: &str,
1976     dox: &str,
1977     link_range: Range<usize>,
1978     failure: AnchorFailure,
1979 ) {
1980     let msg = match failure {
1981         AnchorFailure::MultipleAnchors => format!("`{}` contains multiple anchors", path_str),
1982         AnchorFailure::RustdocAnchorConflict(res) => format!(
1983             "`{}` contains an anchor, but links to {kind}s are already anchored",
1984             path_str,
1985             kind = res.descr(),
1986         ),
1987     };
1988
1989     report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, &msg, item, dox, &link_range, |diag, sp| {
1990         if let Some(sp) = sp {
1991             diag.span_label(sp, "contains invalid anchor");
1992         }
1993     });
1994 }
1995
1996 /// Report an error in the link disambiguator.
1997 fn disambiguator_error(
1998     cx: &DocContext<'_>,
1999     item: &Item,
2000     dox: &str,
2001     link_range: Range<usize>,
2002     msg: &str,
2003 ) {
2004     report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, msg, item, dox, &link_range, |_diag, _sp| {});
2005 }
2006
2007 /// Report an ambiguity error, where there were multiple possible resolutions.
2008 fn ambiguity_error(
2009     cx: &DocContext<'_>,
2010     item: &Item,
2011     path_str: &str,
2012     dox: &str,
2013     link_range: Range<usize>,
2014     candidates: Vec<Res>,
2015 ) {
2016     let mut msg = format!("`{}` is ", path_str);
2017
2018     match candidates.as_slice() {
2019         [first_def, second_def] => {
2020             msg += &format!(
2021                 "both {} {} and {} {}",
2022                 first_def.article(),
2023                 first_def.descr(),
2024                 second_def.article(),
2025                 second_def.descr(),
2026             );
2027         }
2028         _ => {
2029             let mut candidates = candidates.iter().peekable();
2030             while let Some(res) = candidates.next() {
2031                 if candidates.peek().is_some() {
2032                     msg += &format!("{} {}, ", res.article(), res.descr());
2033                 } else {
2034                     msg += &format!("and {} {}", res.article(), res.descr());
2035                 }
2036             }
2037         }
2038     }
2039
2040     report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, &msg, item, dox, &link_range, |diag, sp| {
2041         if let Some(sp) = sp {
2042             diag.span_label(sp, "ambiguous link");
2043         } else {
2044             diag.note("ambiguous link");
2045         }
2046
2047         for res in candidates {
2048             let disambiguator = Disambiguator::from_res(res);
2049             suggest_disambiguator(disambiguator, diag, path_str, dox, sp, &link_range);
2050         }
2051     });
2052 }
2053
2054 /// In case of an ambiguity or mismatched disambiguator, suggest the correct
2055 /// disambiguator.
2056 fn suggest_disambiguator(
2057     disambiguator: Disambiguator,
2058     diag: &mut DiagnosticBuilder<'_>,
2059     path_str: &str,
2060     dox: &str,
2061     sp: Option<rustc_span::Span>,
2062     link_range: &Range<usize>,
2063 ) {
2064     let suggestion = disambiguator.suggestion();
2065     let help = format!("to link to the {}, {}", disambiguator.descr(), suggestion.descr());
2066
2067     if let Some(sp) = sp {
2068         let msg = if dox.bytes().nth(link_range.start) == Some(b'`') {
2069             format!("`{}`", suggestion.as_help(path_str))
2070         } else {
2071             suggestion.as_help(path_str)
2072         };
2073
2074         diag.span_suggestion(sp, &help, msg, Applicability::MaybeIncorrect);
2075     } else {
2076         diag.help(&format!("{}: {}", help, suggestion.as_help(path_str)));
2077     }
2078 }
2079
2080 /// Report a link from a public item to a private one.
2081 fn privacy_error(cx: &DocContext<'_>, item: &Item, path_str: &str, dox: &str, link: &MarkdownLink) {
2082     let sym;
2083     let item_name = match item.name {
2084         Some(name) => {
2085             sym = name.as_str();
2086             &*sym
2087         }
2088         None => "<unknown>",
2089     };
2090     let msg =
2091         format!("public documentation for `{}` links to private item `{}`", item_name, path_str);
2092
2093     report_diagnostic(cx.tcx, PRIVATE_INTRA_DOC_LINKS, &msg, item, dox, &link.range, |diag, sp| {
2094         if let Some(sp) = sp {
2095             diag.span_label(sp, "this item is private");
2096         }
2097
2098         let note_msg = if cx.render_options.document_private {
2099             "this link resolves only because you passed `--document-private-items`, but will break without"
2100         } else {
2101             "this link will resolve properly if you pass `--document-private-items`"
2102         };
2103         diag.note(note_msg);
2104     });
2105 }
2106
2107 /// Given an enum variant's res, return the res of its enum and the associated fragment.
2108 fn handle_variant(
2109     cx: &DocContext<'_>,
2110     res: Res,
2111     extra_fragment: &Option<String>,
2112 ) -> Result<(Res, Option<String>), ErrorKind<'static>> {
2113     use rustc_middle::ty::DefIdTree;
2114
2115     if extra_fragment.is_some() {
2116         return Err(ErrorKind::AnchorFailure(AnchorFailure::RustdocAnchorConflict(res)));
2117     }
2118     cx.tcx
2119         .parent(res.def_id())
2120         .map(|parent| {
2121             let parent_def = Res::Def(DefKind::Enum, parent);
2122             let variant = cx.tcx.expect_variant_res(res.as_hir_res().unwrap());
2123             (parent_def, Some(format!("variant.{}", variant.ident.name)))
2124         })
2125         .ok_or_else(|| ResolutionFailure::NoParentItem.into())
2126 }
2127
2128 /// Resolve a primitive type or value.
2129 fn resolve_primitive(path_str: &str, ns: Namespace) -> Option<Res> {
2130     if ns != TypeNS {
2131         return None;
2132     }
2133     use PrimitiveType::*;
2134     let prim = match path_str {
2135         "isize" => Isize,
2136         "i8" => I8,
2137         "i16" => I16,
2138         "i32" => I32,
2139         "i64" => I64,
2140         "i128" => I128,
2141         "usize" => Usize,
2142         "u8" => U8,
2143         "u16" => U16,
2144         "u32" => U32,
2145         "u64" => U64,
2146         "u128" => U128,
2147         "f32" => F32,
2148         "f64" => F64,
2149         "char" => Char,
2150         "bool" | "true" | "false" => Bool,
2151         "str" | "&str" => Str,
2152         // See #80181 for why these don't have symbols associated.
2153         "slice" => Slice,
2154         "array" => Array,
2155         "tuple" => Tuple,
2156         "unit" => Unit,
2157         "pointer" | "*const" | "*mut" => RawPointer,
2158         "reference" | "&" | "&mut" => Reference,
2159         "fn" => Fn,
2160         "never" | "!" => Never,
2161         _ => return None,
2162     };
2163     debug!("resolved primitives {:?}", prim);
2164     Some(Res::Primitive(prim))
2165 }
2166
2167 fn strip_generics_from_path(path_str: &str) -> Result<String, ResolutionFailure<'static>> {
2168     let mut stripped_segments = vec![];
2169     let mut path = path_str.chars().peekable();
2170     let mut segment = Vec::new();
2171
2172     while let Some(chr) = path.next() {
2173         match chr {
2174             ':' => {
2175                 if path.next_if_eq(&':').is_some() {
2176                     let stripped_segment =
2177                         strip_generics_from_path_segment(mem::take(&mut segment))?;
2178                     if !stripped_segment.is_empty() {
2179                         stripped_segments.push(stripped_segment);
2180                     }
2181                 } else {
2182                     return Err(ResolutionFailure::MalformedGenerics(
2183                         MalformedGenerics::InvalidPathSeparator,
2184                     ));
2185                 }
2186             }
2187             '<' => {
2188                 segment.push(chr);
2189
2190                 match path.next() {
2191                     Some('<') => {
2192                         return Err(ResolutionFailure::MalformedGenerics(
2193                             MalformedGenerics::TooManyAngleBrackets,
2194                         ));
2195                     }
2196                     Some('>') => {
2197                         return Err(ResolutionFailure::MalformedGenerics(
2198                             MalformedGenerics::EmptyAngleBrackets,
2199                         ));
2200                     }
2201                     Some(chr) => {
2202                         segment.push(chr);
2203
2204                         while let Some(chr) = path.next_if(|c| *c != '>') {
2205                             segment.push(chr);
2206                         }
2207                     }
2208                     None => break,
2209                 }
2210             }
2211             _ => segment.push(chr),
2212         }
2213         trace!("raw segment: {:?}", segment);
2214     }
2215
2216     if !segment.is_empty() {
2217         let stripped_segment = strip_generics_from_path_segment(segment)?;
2218         if !stripped_segment.is_empty() {
2219             stripped_segments.push(stripped_segment);
2220         }
2221     }
2222
2223     debug!("path_str: {:?}\nstripped segments: {:?}", path_str, &stripped_segments);
2224
2225     let stripped_path = stripped_segments.join("::");
2226
2227     if !stripped_path.is_empty() {
2228         Ok(stripped_path)
2229     } else {
2230         Err(ResolutionFailure::MalformedGenerics(MalformedGenerics::MissingType))
2231     }
2232 }
2233
2234 fn strip_generics_from_path_segment(
2235     segment: Vec<char>,
2236 ) -> Result<String, ResolutionFailure<'static>> {
2237     let mut stripped_segment = String::new();
2238     let mut param_depth = 0;
2239
2240     let mut latest_generics_chunk = String::new();
2241
2242     for c in segment {
2243         if c == '<' {
2244             param_depth += 1;
2245             latest_generics_chunk.clear();
2246         } else if c == '>' {
2247             param_depth -= 1;
2248             if latest_generics_chunk.contains(" as ") {
2249                 // The segment tries to use fully-qualified syntax, which is currently unsupported.
2250                 // Give a helpful error message instead of completely ignoring the angle brackets.
2251                 return Err(ResolutionFailure::MalformedGenerics(
2252                     MalformedGenerics::HasFullyQualifiedSyntax,
2253                 ));
2254             }
2255         } else {
2256             if param_depth == 0 {
2257                 stripped_segment.push(c);
2258             } else {
2259                 latest_generics_chunk.push(c);
2260             }
2261         }
2262     }
2263
2264     if param_depth == 0 {
2265         Ok(stripped_segment)
2266     } else {
2267         // The segment has unbalanced angle brackets, e.g. `Vec<T` or `Vec<T>>`
2268         Err(ResolutionFailure::MalformedGenerics(MalformedGenerics::UnbalancedAngleBrackets))
2269     }
2270 }