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     ///
 372     /// HACK(jynelson): `item_str` is passed in instead of derived from `item_name` so the
 373     /// lifetimes on `&'path` will work.
 374     fn resolve_primitive_associated_item(
 375         &self,
 376         prim_ty: PrimitiveType,
 377         ns: Namespace,
 378         module_id: DefId,
 379         item_name: Symbol,
 380         item_str: &'path str,
 381     ) -> Result<(Res, Option<String>), ErrorKind<'path>> {
 382         let tcx = self.cx.tcx;
 383
 384         prim_ty
 385             .impls(tcx)
 386             .into_iter()
 387             .find_map(|&impl_| {
 388                 tcx.associated_items(impl_)
 389                     .find_by_name_and_namespace(tcx, Ident::with_dummy_span(item_name), ns, impl_)
 390                     .map(|item| {
 391                         let kind = item.kind;
 392                         self.kind_side_channel.set(Some((kind.as_def_kind(), item.def_id)));
 393                         match kind {
 394                             ty::AssocKind::Fn => "method",
 395                             ty::AssocKind::Const => "associatedconstant",
 396                             ty::AssocKind::Type => "associatedtype",
 397                         }
 398                     })
 399                     .map(|out| {
 400                         (
 401                             Res::Primitive(prim_ty),
 402                             Some(format!("{}#{}.{}", prim_ty.as_str(), out, item_str)),
 403                         )
 404                     })
 405             })
 406             .ok_or_else(|| {
 407                 debug!(
 408                     "returning primitive error for {}::{} in {} namespace",
 409                     prim_ty.as_str(),
 410                     item_name,
 411                     ns.descr()
 412                 );
 413                 ResolutionFailure::NotResolved {
 414                     module_id,
 415                     partial_res: Some(Res::Primitive(prim_ty)),
 416                     unresolved: item_str.into(),
 417                 }
 418                 .into()
 419             })
 420     }
 421
 422     /// Resolves a string as a macro.
 423     ///
 424     /// FIXME(jynelson): Can this be unified with `resolve()`?
 425     fn resolve_macro(
 426         &self,
 427         path_str: &'a str,
 428         module_id: DefId,
 429     ) -> Result<Res, ResolutionFailure<'a>> {
 430         let path = ast::Path::from_ident(Ident::from_str(path_str));
 431         self.cx.enter_resolver(|resolver| {
 432             // FIXME(jynelson): does this really need 3 separate lookups?
 433             if let Ok((Some(ext), res)) = resolver.resolve_macro_path(
 434                 &path,
 435                 None,
 436                 &ParentScope::module(resolver.graph_root(), resolver),
 437                 false,
 438                 false,
 439             ) {
 440                 if let SyntaxExtensionKind::LegacyBang { .. } = ext.kind {
 441                     return Ok(res.try_into().unwrap());
 442                 }
 443             }
 444             if let Some(&res) = resolver.all_macros().get(&Symbol::intern(path_str)) {
 445                 return Ok(res.try_into().unwrap());
 446             }
 447             debug!("resolving {} as a macro in the module {:?}", path_str, module_id);
 448             if let Ok((_, res)) =
 449                 resolver.resolve_str_path_error(DUMMY_SP, path_str, MacroNS, module_id)
 450             {
 451                 // don't resolve builtins like `#[derive]`
 452                 if let Ok(res) = res.try_into() {
 453                     return Ok(res);
 454                 }
 455             }
 456             Err(ResolutionFailure::NotResolved {
 457                 module_id,
 458                 partial_res: None,
 459                 unresolved: path_str.into(),
 460             })
 461         })
 462     }
 463
 464     /// Convenience wrapper around `resolve_str_path_error`.
 465     ///
 466     /// This also handles resolving `true` and `false` as booleans.
 467     /// NOTE: `resolve_str_path_error` knows only about paths, not about types.
 468     /// Associated items will never be resolved by this function.
 469     fn resolve_path(&self, path_str: &str, ns: Namespace, module_id: DefId) -> Option<Res> {
 470         let result = self.cx.enter_resolver(|resolver| {
 471             resolver
 472                 .resolve_str_path_error(DUMMY_SP, &path_str, ns, module_id)
 473                 .and_then(|(_, res)| res.try_into())
 474         });
 475         debug!("{} resolved to {:?} in namespace {:?}", path_str, result, ns);
 476         match result {
 477             // resolver doesn't know about true, false, and types that aren't paths (e.g. `()`)
 478             // manually as bool
 479             Err(()) => resolve_primitive(path_str, ns),
 480             Ok(res) => Some(res),
 481         }
 482     }
 483
 484     /// Resolves a string as a path within a particular namespace. Returns an
 485     /// optional URL fragment in the case of variants and methods.
 486     fn resolve<'path>(
 487         &mut self,
 488         path_str: &'path str,
 489         ns: Namespace,
 490         module_id: DefId,
 491         extra_fragment: &Option<String>,
 492     ) -> Result<(Res, Option<String>), ErrorKind<'path>> {
 493         let tcx = self.cx.tcx;
 494
 495         if let Some(res) = self.resolve_path(path_str, ns, module_id) {
 496             match res {
 497                 // FIXME(#76467): make this fallthrough to lookup the associated
 498                 // item a separate function.
 499                 Res::Def(DefKind::AssocFn | DefKind::AssocConst, _) => assert_eq!(ns, ValueNS),
 500                 Res::Def(DefKind::AssocTy, _) => assert_eq!(ns, TypeNS),
 501                 Res::Def(DefKind::Variant, _) => {
 502                     return handle_variant(self.cx, res, extra_fragment);
 503                 }
 504                 // Not a trait item; just return what we found.
 505                 Res::Primitive(ty) => {
 506                     if extra_fragment.is_some() {
 507                         return Err(ErrorKind::AnchorFailure(
 508                             AnchorFailure::RustdocAnchorConflict(res),
 509                         ));
 510                     }
 511                     return Ok((res, Some(ty.as_str().to_owned())));
 512                 }
 513                 _ => return Ok((res, extra_fragment.clone())),
 514             }
 515         }
 516
 517         // Try looking for methods and associated items.
 518         let mut split = path_str.rsplitn(2, "::");
 519         // NB: `split`'s first element is always defined, even if the delimiter was not present.
 520         // NB: `item_str` could be empty when resolving in the root namespace (e.g. `::std`).
 521         let item_str = split.next().unwrap();
 522         let item_name = Symbol::intern(item_str);
 523         let path_root = split
 524             .next()
 525             .map(|f| f.to_owned())
 526             // If there's no `::`, it's not an associated item.
 527             // So we can be sure that `rustc_resolve` was accurate when it said it wasn't resolved.
 528             .ok_or_else(|| {
 529                 debug!("found no `::`, assumming {} was correctly not in scope", item_name);
 530                 ResolutionFailure::NotResolved {
 531                     module_id,
 532                     partial_res: None,
 533                     unresolved: item_str.into(),
 534                 }
 535             })?;
 536
 537         // FIXME: are these both necessary?
 538         let ty_res = if let Some(ty_res) = resolve_primitive(&path_root, TypeNS)
 539             .or_else(|| self.resolve_path(&path_root, TypeNS, module_id))
 540         {
 541             ty_res
 542         } else {
 543             // FIXME: this is duplicated on the end of this function.
 544             return if ns == Namespace::ValueNS {
 545                 self.variant_field(path_str, module_id)
 546             } else {
 547                 Err(ResolutionFailure::NotResolved {
 548                     module_id,
 549                     partial_res: None,
 550                     unresolved: path_root.into(),
 551                 }
 552                 .into())
 553             };
 554         };
 555
 556         let res = match ty_res {
 557             Res::Primitive(prim) => Some(
 558                 self.resolve_primitive_associated_item(prim, ns, module_id, item_name, item_str),
 559             ),
 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                     Some(if extra_fragment.is_some() {
 603                         Err(ErrorKind::AnchorFailure(AnchorFailure::RustdocAnchorConflict(ty_res)))
 604                     } else {
 605                         // HACK(jynelson): `clean` expects the type, not the associated item
 606                         // but the disambiguator logic expects the associated item.
 607                         // Store the kind in a side channel so that only the disambiguator logic looks at it.
 608                         self.kind_side_channel.set(Some((kind.as_def_kind(), id)));
 609                         Ok((ty_res, Some(format!("{}.{}", out, item_str))))
 610                     })
 611                 } else if ns == Namespace::ValueNS {
 612                     debug!("looking for variants or fields named {} for {:?}", item_name, did);
 613                     // FIXME(jynelson): why is this different from
 614                     // `variant_field`?
 615                     match tcx.type_of(did).kind() {
 616                         ty::Adt(def, _) => {
 617                             let field = if def.is_enum() {
 618                                 def.all_fields().find(|item| item.ident.name == item_name)
 619                             } else {
 620                                 def.non_enum_variant()
 621                                     .fields
 622                                     .iter()
 623                                     .find(|item| item.ident.name == item_name)
 624                             };
 625                             field.map(|item| {
 626                                 if extra_fragment.is_some() {
 627                                     let res = Res::Def(
 628                                         if def.is_enum() {
 629                                             DefKind::Variant
 630                                         } else {
 631                                             DefKind::Field
 632                                         },
 633                                         item.did,
 634                                     );
 635                                     Err(ErrorKind::AnchorFailure(
 636                                         AnchorFailure::RustdocAnchorConflict(res),
 637                                     ))
 638                                 } else {
 639                                     Ok((
 640                                         ty_res,
 641                                         Some(format!(
 642                                             "{}.{}",
 643                                             if def.is_enum() { "variant" } else { "structfield" },
 644                                             item.ident
 645                                         )),
 646                                     ))
 647                                 }
 648                             })
 649                         }
 650                         _ => None,
 651                     }
 652                 } else {
 653                     None
 654                 }
 655             }
 656             Res::Def(DefKind::Trait, did) => tcx
 657                 .associated_items(did)
 658                 .find_by_name_and_namespace(tcx, Ident::with_dummy_span(item_name), ns, did)
 659                 .map(|item| {
 660                     let kind = match item.kind {
 661                         ty::AssocKind::Const => "associatedconstant",
 662                         ty::AssocKind::Type => "associatedtype",
 663                         ty::AssocKind::Fn => {
 664                             if item.defaultness.has_value() {
 665                                 "method"
 666                             } else {
 667                                 "tymethod"
 668                             }
 669                         }
 670                     };
 671
 672                     if extra_fragment.is_some() {
 673                         Err(ErrorKind::AnchorFailure(AnchorFailure::RustdocAnchorConflict(ty_res)))
 674                     } else {
 675                         let res = Res::Def(item.kind.as_def_kind(), item.def_id);
 676                         Ok((res, Some(format!("{}.{}", kind, item_str))))
 677                     }
 678                 }),
 679             _ => None,
 680         };
 681         res.unwrap_or_else(|| {
 682             if ns == Namespace::ValueNS {
 683                 self.variant_field(path_str, module_id)
 684             } else {
 685                 Err(ResolutionFailure::NotResolved {
 686                     module_id,
 687                     partial_res: Some(ty_res),
 688                     unresolved: item_str.into(),
 689                 }
 690                 .into())
 691             }
 692         })
 693     }
 694
 695     /// Used for reporting better errors.
 696     ///
 697     /// Returns whether the link resolved 'fully' in another namespace.
 698     /// 'fully' here means that all parts of the link resolved, not just some path segments.
 699     /// This returns the `Res` even if it was erroneous for some reason
 700     /// (such as having invalid URL fragments or being in the wrong namespace).
 701     fn check_full_res(
 702         &mut self,
 703         ns: Namespace,
 704         path_str: &str,
 705         module_id: DefId,
 706         extra_fragment: &Option<String>,
 707     ) -> Option<Res> {
 708         // resolve() can't be used for macro namespace
 709         let result = match ns {
 710             Namespace::MacroNS => self.resolve_macro(path_str, module_id).map_err(ErrorKind::from),
 711             Namespace::TypeNS | Namespace::ValueNS => {
 712                 self.resolve(path_str, ns, module_id, extra_fragment).map(|(res, _)| res)
 713             }
 714         };
 715
 716         let res = match result {
 717             Ok(res) => Some(res),
 718             Err(ErrorKind::Resolve(box kind)) => kind.full_res(),
 719             Err(ErrorKind::AnchorFailure(AnchorFailure::RustdocAnchorConflict(res))) => Some(res),
 720             Err(ErrorKind::AnchorFailure(AnchorFailure::MultipleAnchors)) => None,
 721         };
 722         self.kind_side_channel.take().map(|(kind, id)| Res::Def(kind, id)).or(res)
 723     }
 724 }
 725
 726 /// Look to see if a resolved item has an associated item named `item_name`.
 727 ///
 728 /// Given `[std::io::Error::source]`, where `source` is unresolved, this would
 729 /// find `std::error::Error::source` and return
 730 /// `<io::Error as error::Error>::source`.
 731 fn resolve_associated_trait_item(
 732     did: DefId,
 733     module: DefId,
 734     item_name: Symbol,
 735     ns: Namespace,
 736     cx: &mut DocContext<'_>,
 737 ) -> Option<(ty::AssocKind, DefId)> {
 738     // FIXME: this should also consider blanket impls (`impl<T> X for T`). Unfortunately
 739     // `get_auto_trait_and_blanket_impls` is broken because the caching behavior is wrong. In the
 740     // meantime, just don't look for these blanket impls.
 741
 742     // Next consider explicit impls: `impl MyTrait for MyType`
 743     // Give precedence to inherent impls.
 744     let traits = traits_implemented_by(cx, did, module);
 745     debug!("considering traits {:?}", traits);
 746     let mut candidates = traits.iter().filter_map(|&trait_| {
 747         cx.tcx
 748             .associated_items(trait_)
 749             .find_by_name_and_namespace(cx.tcx, Ident::with_dummy_span(item_name), ns, trait_)
 750             .map(|assoc| (assoc.kind, assoc.def_id))
 751     });
 752     // FIXME(#74563): warn about ambiguity
 753     debug!("the candidates were {:?}", candidates.clone().collect::<Vec<_>>());
 754     candidates.next()
 755 }
 756
 757 /// Given a type, return all traits in scope in `module` implemented by that type.
 758 ///
 759 /// NOTE: this cannot be a query because more traits could be available when more crates are compiled!
 760 /// So it is not stable to serialize cross-crate.
 761 fn traits_implemented_by(cx: &mut DocContext<'_>, type_: DefId, module: DefId) -> FxHashSet<DefId> {
 762     let mut resolver = cx.resolver.borrow_mut();
 763     let in_scope_traits = cx.module_trait_cache.entry(module).or_insert_with(|| {
 764         resolver.access(|resolver| {
 765             let parent_scope = &ParentScope::module(resolver.get_module(module), resolver);
 766             resolver
 767                 .traits_in_scope(None, parent_scope, SyntaxContext::root(), None)
 768                 .into_iter()
 769                 .map(|candidate| candidate.def_id)
 770                 .collect()
 771         })
 772     });
 773
 774     let tcx = cx.tcx;
 775     let ty = tcx.type_of(type_);
 776     let iter = in_scope_traits.iter().flat_map(|&trait_| {
 777         trace!("considering explicit impl for trait {:?}", trait_);
 778
 779         // Look at each trait implementation to see if it's an impl for `did`
 780         tcx.find_map_relevant_impl(trait_, ty, |impl_| {
 781             let trait_ref = tcx.impl_trait_ref(impl_).expect("this is not an inherent impl");
 782             // Check if these are the same type.
 783             let impl_type = trait_ref.self_ty();
 784             trace!(
 785                 "comparing type {} with kind {:?} against type {:?}",
 786                 impl_type,
 787                 impl_type.kind(),
 788                 type_
 789             );
 790             // Fast path: if this is a primitive simple `==` will work
 791             let saw_impl = impl_type == ty
 792                 || match impl_type.kind() {
 793                     // Check if these are the same def_id
 794                     ty::Adt(def, _) => {
 795                         debug!("adt def_id: {:?}", def.did);
 796                         def.did == type_
 797                     }
 798                     ty::Foreign(def_id) => *def_id == type_,
 799                     _ => false,
 800                 };
 801
 802             if saw_impl { Some(trait_) } else { None }
 803         })
 804     });
 805     iter.collect()
 806 }
 807
 808 /// Check for resolve collisions between a trait and its derive.
 809 ///
 810 /// These are common and we should just resolve to the trait in that case.
 811 fn is_derive_trait_collision<T>(ns: &PerNS<Result<(Res, T), ResolutionFailure<'_>>>) -> bool {
 812     matches!(
 813         *ns,
 814         PerNS {
 815             type_ns: Ok((Res::Def(DefKind::Trait, _), _)),
 816             macro_ns: Ok((Res::Def(DefKind::Macro(MacroKind::Derive), _), _)),
 817             ..
 818         }
 819     )
 820 }
 821
 822 impl<'a, 'tcx> DocFolder for LinkCollector<'a, 'tcx> {
 823     fn fold_item(&mut self, mut item: Item) -> Option<Item> {
 824         use rustc_middle::ty::DefIdTree;
 825
 826         let parent_node = if item.is_fake() {
 827             None
 828         } else {
 829             find_nearest_parent_module(self.cx.tcx, item.def_id)
 830         };
 831
 832         if parent_node.is_some() {
 833             trace!("got parent node for {:?} {:?}, id {:?}", item.type_(), item.name, item.def_id);
 834         }
 835
 836         // find item's parent to resolve `Self` in item's docs below
 837         debug!("looking for the `Self` type");
 838         let self_id = if item.is_fake() {
 839             None
 840         // Checking if the item is a field in an enum variant
 841         } else if (matches!(self.cx.tcx.def_kind(item.def_id), DefKind::Field)
 842             && matches!(
 843                 self.cx.tcx.def_kind(self.cx.tcx.parent(item.def_id).unwrap()),
 844                 DefKind::Variant
 845             ))
 846         {
 847             self.cx.tcx.parent(item.def_id).and_then(|item_id| self.cx.tcx.parent(item_id))
 848         } else if matches!(
 849             self.cx.tcx.def_kind(item.def_id),
 850             DefKind::AssocConst
 851                 | DefKind::AssocFn
 852                 | DefKind::AssocTy
 853                 | DefKind::Variant
 854                 | DefKind::Field
 855         ) {
 856             self.cx.tcx.parent(item.def_id)
 857         // HACK(jynelson): `clean` marks associated types as `TypedefItem`, not as `AssocTypeItem`.
 858         // Fixing this breaks `fn render_deref_methods`.
 859         // As a workaround, see if the parent of the item is an `impl`; if so this must be an associated item,
 860         // regardless of what rustdoc wants to call it.
 861         } else if let Some(parent) = self.cx.tcx.parent(item.def_id) {
 862             let parent_kind = self.cx.tcx.def_kind(parent);
 863             Some(if parent_kind == DefKind::Impl { parent } else { item.def_id })
 864         } else {
 865             Some(item.def_id)
 866         };
 867
 868         // FIXME(jynelson): this shouldn't go through stringification, rustdoc should just use the DefId directly
 869         let self_name = self_id.and_then(|self_id| {
 870             if matches!(self.cx.tcx.def_kind(self_id), DefKind::Impl) {
 871                 // using `ty.to_string()` (or any variant) has issues with raw idents
 872                 let ty = self.cx.tcx.type_of(self_id);
 873                 let name = match ty.kind() {
 874                     ty::Adt(def, _) => Some(self.cx.tcx.item_name(def.did).to_string()),
 875                     other if other.is_primitive() => Some(ty.to_string()),
 876                     _ => None,
 877                 };
 878                 debug!("using type_of(): {:?}", name);
 879                 name
 880             } else {
 881                 let name = self.cx.tcx.opt_item_name(self_id).map(|sym| sym.to_string());
 882                 debug!("using item_name(): {:?}", name);
 883                 name
 884             }
 885         });
 886
 887         if item.is_mod() && item.attrs.inner_docs {
 888             self.mod_ids.push(item.def_id);
 889         }
 890
 891         // We want to resolve in the lexical scope of the documentation.
 892         // In the presence of re-exports, this is not the same as the module of the item.
 893         // Rather than merging all documentation into one, resolve it one attribute at a time
 894         // so we know which module it came from.
 895         for (parent_module, doc) in item.attrs.collapsed_doc_value_by_module_level() {
 896             debug!("combined_docs={}", doc);
 897
 898             let (krate, parent_node) = if let Some(id) = parent_module {
 899                 (id.krate, Some(id))
 900             } else {
 901                 (item.def_id.krate, parent_node)
 902             };
 903             // NOTE: if there are links that start in one crate and end in another, this will not resolve them.
 904             // This is a degenerate case and it's not supported by rustdoc.
 905             for md_link in markdown_links(&doc) {
 906                 let link = self.resolve_link(&item, &doc, &self_name, parent_node, krate, md_link);
 907                 if let Some(link) = link {
 908                     item.attrs.links.push(link);
 909                 }
 910             }
 911         }
 912
 913         Some(if item.is_mod() {
 914             if !item.attrs.inner_docs {
 915                 self.mod_ids.push(item.def_id);
 916             }
 917
 918             let ret = self.fold_item_recur(item);
 919             self.mod_ids.pop();
 920             ret
 921         } else {
 922             self.fold_item_recur(item)
 923         })
 924     }
 925 }
 926
 927 impl LinkCollector<'_, '_> {
 928     /// This is the entry point for resolving an intra-doc link.
 929     ///
 930     /// FIXME(jynelson): this is way too many arguments
 931     fn resolve_link(
 932         &mut self,
 933         item: &Item,
 934         dox: &str,
 935         self_name: &Option<String>,
 936         parent_node: Option<DefId>,
 937         krate: CrateNum,
 938         ori_link: MarkdownLink,
 939     ) -> Option<ItemLink> {
 940         trace!("considering link '{}'", ori_link.link);
 941
 942         // Bail early for real links.
 943         if ori_link.link.contains('/') {
 944             return None;
 945         }
 946
 947         // [] is mostly likely not supposed to be a link
 948         if ori_link.link.is_empty() {
 949             return None;
 950         }
 951
 952         let link = ori_link.link.replace("`", "");
 953         let no_backticks_range = range_between_backticks(&ori_link);
 954         let parts = link.split('#').collect::<Vec<_>>();
 955         let (link, extra_fragment) = if parts.len() > 2 {
 956             // A valid link can't have multiple #'s
 957             anchor_failure(
 958                 self.cx,
 959                 &item,
 960                 &link,
 961                 dox,
 962                 ori_link.range,
 963                 AnchorFailure::MultipleAnchors,
 964             );
 965             return None;
 966         } else if parts.len() == 2 {
 967             if parts[0].trim().is_empty() {
 968                 // This is an anchor to an element of the current page, nothing to do in here!
 969                 return None;
 970             }
 971             (parts[0], Some(parts[1].to_owned()))
 972         } else {
 973             (parts[0], None)
 974         };
 975
 976         // Parse and strip the disambiguator from the link, if present.
 977         let (mut path_str, disambiguator) = match Disambiguator::from_str(&link) {
 978             Ok(Some((d, path))) => (path.trim(), Some(d)),
 979             Ok(None) => (link.trim(), None),
 980             Err((err_msg, relative_range)) => {
 981                 let disambiguator_range = (no_backticks_range.start + relative_range.start)
 982                     ..(no_backticks_range.start + relative_range.end);
 983                 disambiguator_error(self.cx, &item, dox, disambiguator_range, &err_msg);
 984                 return None;
 985             }
 986         };
 987
 988         if path_str.contains(|ch: char| !(ch.is_alphanumeric() || ":_<>, !*&;".contains(ch))) {
 989             return None;
 990         }
 991
 992         // We stripped `()` and `!` when parsing the disambiguator.
 993         // Add them back to be displayed, but not prefix disambiguators.
 994         let link_text =
 995             disambiguator.map(|d| d.display_for(path_str)).unwrap_or_else(|| path_str.to_owned());
 996
 997         // In order to correctly resolve intra-doc links we need to
 998         // pick a base AST node to work from.  If the documentation for
 999         // this module came from an inner comment (//!) then we anchor
1000         // our name resolution *inside* the module.  If, on the other
1001         // hand it was an outer comment (///) then we anchor the name
1002         // resolution in the parent module on the basis that the names
1003         // used are more likely to be intended to be parent names.  For
1004         // this, we set base_node to None for inner comments since
1005         // we've already pushed this node onto the resolution stack but
1006         // for outer comments we explicitly try and resolve against the
1007         // parent_node first.
1008         let base_node = if item.is_mod() && item.attrs.inner_docs {
1009             self.mod_ids.last().copied()
1010         } else {
1011             parent_node
1012         };
1013
1014         let mut module_id = if let Some(id) = base_node {
1015             id
1016         } else {
1017             // This is a bug.
1018             debug!("attempting to resolve item without parent module: {}", path_str);
1019             resolution_failure(
1020                 self,
1021                 &item,
1022                 path_str,
1023                 disambiguator,
1024                 dox,
1025                 ori_link.range,
1026                 smallvec![ResolutionFailure::NoParentItem],
1027             );
1028             return None;
1029         };
1030
1031         let resolved_self;
1032         // replace `Self` with suitable item's parent name
1033         let is_lone_self = path_str == "Self";
1034         let is_lone_crate = path_str == "crate";
1035         if path_str.starts_with("Self::") || is_lone_self {
1036             if let Some(ref name) = self_name {
1037                 if is_lone_self {
1038                     path_str = name;
1039                 } else {
1040                     resolved_self = format!("{}::{}", name, &path_str[6..]);
1041                     path_str = &resolved_self;
1042                 }
1043             }
1044         } else if path_str.starts_with("crate::") || is_lone_crate {
1045             use rustc_span::def_id::CRATE_DEF_INDEX;
1046
1047             // HACK(jynelson): rustc_resolve thinks that `crate` is the crate currently being documented.
1048             // But rustdoc wants it to mean the crate this item was originally present in.
1049             // To work around this, remove it and resolve relative to the crate root instead.
1050             // HACK(jynelson)(2): If we just strip `crate::` then suddenly primitives become ambiguous
1051             // (consider `crate::char`). Instead, change it to `self::`. This works because 'self' is now the crate root.
1052             // FIXME(#78696): This doesn't always work.
1053             if is_lone_crate {
1054                 path_str = "self";
1055             } else {
1056                 resolved_self = format!("self::{}", &path_str["crate::".len()..]);
1057                 path_str = &resolved_self;
1058             }
1059             module_id = DefId { krate, index: CRATE_DEF_INDEX };
1060         }
1061
1062         // Strip generics from the path.
1063         let stripped_path_string;
1064         if path_str.contains(['<', '>'].as_slice()) {
1065             stripped_path_string = match strip_generics_from_path(path_str) {
1066                 Ok(path) => path,
1067                 Err(err_kind) => {
1068                     debug!("link has malformed generics: {}", path_str);
1069                     resolution_failure(
1070                         self,
1071                         &item,
1072                         path_str,
1073                         disambiguator,
1074                         dox,
1075                         ori_link.range,
1076                         smallvec![err_kind],
1077                     );
1078                     return None;
1079                 }
1080             };
1081             path_str = &stripped_path_string;
1082         }
1083         // Sanity check to make sure we don't have any angle brackets after stripping generics.
1084         assert!(!path_str.contains(['<', '>'].as_slice()));
1085
1086         // The link is not an intra-doc link if it still contains spaces after stripping generics.
1087         if path_str.contains(' ') {
1088             return None;
1089         }
1090
1091         let diag_info = DiagnosticInfo {
1092             item,
1093             dox,
1094             ori_link: &ori_link.link,
1095             link_range: ori_link.range.clone(),
1096         };
1097         let (mut res, mut fragment) = self.resolve_with_disambiguator_cached(
1098             ResolutionInfo {
1099                 module_id,
1100                 dis: disambiguator,
1101                 path_str: path_str.to_owned(),
1102                 extra_fragment,
1103             },
1104             diag_info,
1105             matches!(ori_link.kind, LinkType::Reference | LinkType::Shortcut),
1106         )?;
1107
1108         // Check for a primitive which might conflict with a module
1109         // Report the ambiguity and require that the user specify which one they meant.
1110         // FIXME: could there ever be a primitive not in the type namespace?
1111         if matches!(
1112             disambiguator,
1113             None | Some(Disambiguator::Namespace(Namespace::TypeNS) | Disambiguator::Primitive)
1114         ) && !matches!(res, Res::Primitive(_))
1115         {
1116             if let Some(prim) = resolve_primitive(path_str, TypeNS) {
1117                 // `prim@char`
1118                 if matches!(disambiguator, Some(Disambiguator::Primitive)) {
1119                     if fragment.is_some() {
1120                         anchor_failure(
1121                             self.cx,
1122                             &item,
1123                             path_str,
1124                             dox,
1125                             ori_link.range,
1126                             AnchorFailure::RustdocAnchorConflict(prim),
1127                         );
1128                         return None;
1129                     }
1130                     res = prim;
1131                     fragment = Some(prim.name(self.cx.tcx));
1132                 } else {
1133                     // `[char]` when a `char` module is in scope
1134                     let candidates = vec![res, prim];
1135                     ambiguity_error(self.cx, &item, path_str, dox, ori_link.range, candidates);
1136                     return None;
1137                 }
1138             }
1139         }
1140
1141         let report_mismatch = |specified: Disambiguator, resolved: Disambiguator| {
1142             // The resolved item did not match the disambiguator; give a better error than 'not found'
1143             let msg = format!("incompatible link kind for `{}`", path_str);
1144             let callback = |diag: &mut DiagnosticBuilder<'_>, sp| {
1145                 let note = format!(
1146                     "this link resolved to {} {}, which is not {} {}",
1147                     resolved.article(),
1148                     resolved.descr(),
1149                     specified.article(),
1150                     specified.descr()
1151                 );
1152                 diag.note(&note);
1153                 suggest_disambiguator(resolved, diag, path_str, dox, sp, &ori_link.range);
1154             };
1155             report_diagnostic(
1156                 self.cx.tcx,
1157                 BROKEN_INTRA_DOC_LINKS,
1158                 &msg,
1159                 &item,
1160                 dox,
1161                 &ori_link.range,
1162                 callback,
1163             );
1164         };
1165
1166         let verify = |kind: DefKind, id: DefId| {
1167             let (kind, id) = self.kind_side_channel.take().unwrap_or((kind, id));
1168             debug!("intra-doc link to {} resolved to {:?} (id: {:?})", path_str, res, id);
1169
1170             // Disallow e.g. linking to enums with `struct@`
1171             debug!("saw kind {:?} with disambiguator {:?}", kind, disambiguator);
1172             match (kind, disambiguator) {
1173                 | (DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst, Some(Disambiguator::Kind(DefKind::Const)))
1174                 // NOTE: this allows 'method' to mean both normal functions and associated functions
1175                 // This can't cause ambiguity because both are in the same namespace.
1176                 | (DefKind::Fn | DefKind::AssocFn, Some(Disambiguator::Kind(DefKind::Fn)))
1177                 // These are namespaces; allow anything in the namespace to match
1178                 | (_, Some(Disambiguator::Namespace(_)))
1179                 // If no disambiguator given, allow anything
1180                 | (_, None)
1181                 // All of these are valid, so do nothing
1182                 => {}
1183                 (actual, Some(Disambiguator::Kind(expected))) if actual == expected => {}
1184                 (_, Some(specified @ Disambiguator::Kind(_) | specified @ Disambiguator::Primitive)) => {
1185                     report_mismatch(specified, Disambiguator::Kind(kind));
1186                     return None;
1187                 }
1188             }
1189
1190             // item can be non-local e.g. when using #[doc(primitive = "pointer")]
1191             if let Some((src_id, dst_id)) = id
1192                 .as_local()
1193                 .and_then(|dst_id| item.def_id.as_local().map(|src_id| (src_id, dst_id)))
1194             {
1195                 use rustc_hir::def_id::LOCAL_CRATE;
1196
1197                 let hir_src = self.cx.tcx.hir().local_def_id_to_hir_id(src_id);
1198                 let hir_dst = self.cx.tcx.hir().local_def_id_to_hir_id(dst_id);
1199
1200                 if self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_src)
1201                     && !self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_dst)
1202                 {
1203                     privacy_error(self.cx, &item, &path_str, dox, &ori_link);
1204                 }
1205             }
1206
1207             Some(())
1208         };
1209
1210         match res {
1211             Res::Primitive(prim) => {
1212                 if let Some((kind, id)) = self.kind_side_channel.take() {
1213                     // We're actually resolving an associated item of a primitive, so we need to
1214                     // verify the disambiguator (if any) matches the type of the associated item.
1215                     // This case should really follow the same flow as the `Res::Def` branch below,
1216                     // but attempting to add a call to `clean::register_res` causes an ICE. @jyn514
1217                     // thinks `register_res` is only needed for cross-crate re-exports, but Rust
1218                     // doesn't allow statements like `use str::trim;`, making this a (hopefully)
1219                     // valid omission. See https://github.com/rust-lang/rust/pull/80660#discussion_r551585677
1220                     // for discussion on the matter.
1221                     verify(kind, id)?;
1222
1223                     // FIXME: it would be nice to check that the feature gate was enabled in the original crate, not just ignore it altogether.
1224                     // However I'm not sure how to check that across crates.
1225                     if prim == PrimitiveType::RawPointer
1226                         && item.def_id.is_local()
1227                         && !self.cx.tcx.features().intra_doc_pointers
1228                     {
1229                         let span = super::source_span_for_markdown_range(
1230                             self.cx.tcx,
1231                             dox,
1232                             &ori_link.range,
1233                             &item.attrs,
1234                         )
1235                         .unwrap_or_else(|| span_of_attrs(&item.attrs).unwrap_or(item.span.inner()));
1236
1237                         rustc_session::parse::feature_err(
1238                             &self.cx.tcx.sess.parse_sess,
1239                             sym::intra_doc_pointers,
1240                             span,
1241                             "linking to associated items of raw pointers is experimental",
1242                         )
1243                         .note("rustdoc does not allow disambiguating between `*const` and `*mut`, and pointers are unstable until it does")
1244                         .emit();
1245                     }
1246                 } else {
1247                     match disambiguator {
1248                         Some(Disambiguator::Primitive | Disambiguator::Namespace(_)) | None => {}
1249                         Some(other) => {
1250                             report_mismatch(other, Disambiguator::Primitive);
1251                             return None;
1252                         }
1253                     }
1254                 }
1255
1256                 Some(ItemLink { link: ori_link.link, link_text, did: None, fragment })
1257             }
1258             Res::Def(kind, id) => {
1259                 verify(kind, id)?;
1260                 let id = clean::register_res(self.cx, rustc_hir::def::Res::Def(kind, id));
1261                 Some(ItemLink { link: ori_link.link, link_text, did: Some(id), fragment })
1262             }
1263         }
1264     }
1265
1266     fn resolve_with_disambiguator_cached(
1267         &mut self,
1268         key: ResolutionInfo,
1269         diag: DiagnosticInfo<'_>,
1270         cache_resolution_failure: bool,
1271     ) -> Option<(Res, Option<String>)> {
1272         // Try to look up both the result and the corresponding side channel value
1273         if let Some(ref cached) = self.visited_links.get(&key) {
1274             match cached {
1275                 Some(cached) => {
1276                     self.kind_side_channel.set(cached.side_channel.clone());
1277                     return Some(cached.res.clone());
1278                 }
1279                 None if cache_resolution_failure => return None,
1280                 None => {
1281                     // Although we hit the cache and found a resolution error, this link isn't
1282                     // supposed to cache those. Run link resolution again to emit the expected
1283                     // resolution error.
1284                 }
1285             }
1286         }
1287
1288         let res = self.resolve_with_disambiguator(&key, diag);
1289
1290         // Cache only if resolved successfully - don't silence duplicate errors
1291         if let Some(res) = res {
1292             // Store result for the actual namespace
1293             self.visited_links.insert(
1294                 key,
1295                 Some(CachedLink {
1296                     res: res.clone(),
1297                     side_channel: self.kind_side_channel.clone().into_inner(),
1298                 }),
1299             );
1300
1301             Some(res)
1302         } else {
1303             if cache_resolution_failure {
1304                 // For reference-style links we only want to report one resolution error
1305                 // so let's cache them as well.
1306                 self.visited_links.insert(key, None);
1307             }
1308
1309             None
1310         }
1311     }
1312
1313     /// After parsing the disambiguator, resolve the main part of the link.
1314     // FIXME(jynelson): wow this is just so much
1315     fn resolve_with_disambiguator(
1316         &mut self,
1317         key: &ResolutionInfo,
1318         diag: DiagnosticInfo<'_>,
1319     ) -> Option<(Res, Option<String>)> {
1320         let disambiguator = key.dis;
1321         let path_str = &key.path_str;
1322         let base_node = key.module_id;
1323         let extra_fragment = &key.extra_fragment;
1324
1325         match disambiguator.map(Disambiguator::ns) {
1326             Some(expected_ns @ (ValueNS | TypeNS)) => {
1327                 match self.resolve(path_str, expected_ns, base_node, extra_fragment) {
1328                     Ok(res) => Some(res),
1329                     Err(ErrorKind::Resolve(box mut kind)) => {
1330                         // We only looked in one namespace. Try to give a better error if possible.
1331                         if kind.full_res().is_none() {
1332                             let other_ns = if expected_ns == ValueNS { TypeNS } else { ValueNS };
1333                             // FIXME: really it should be `resolution_failure` that does this, not `resolve_with_disambiguator`
1334                             // See https://github.com/rust-lang/rust/pull/76955#discussion_r493953382 for a good approach
1335                             for &new_ns in &[other_ns, MacroNS] {
1336                                 if let Some(res) =
1337                                     self.check_full_res(new_ns, path_str, base_node, extra_fragment)
1338                                 {
1339                                     kind = ResolutionFailure::WrongNamespace { res, expected_ns };
1340                                     break;
1341                                 }
1342                             }
1343                         }
1344                         resolution_failure(
1345                             self,
1346                             diag.item,
1347                             path_str,
1348                             disambiguator,
1349                             diag.dox,
1350                             diag.link_range,
1351                             smallvec![kind],
1352                         );
1353                         // This could just be a normal link or a broken link
1354                         // we could potentially check if something is
1355                         // "intra-doc-link-like" and warn in that case.
1356                         None
1357                     }
1358                     Err(ErrorKind::AnchorFailure(msg)) => {
1359                         anchor_failure(
1360                             self.cx,
1361                             diag.item,
1362                             diag.ori_link,
1363                             diag.dox,
1364                             diag.link_range,
1365                             msg,
1366                         );
1367                         None
1368                     }
1369                 }
1370             }
1371             None => {
1372                 // Try everything!
1373                 let mut candidates = PerNS {
1374                     macro_ns: self
1375                         .resolve_macro(path_str, base_node)
1376                         .map(|res| (res, extra_fragment.clone())),
1377                     type_ns: match self.resolve(path_str, TypeNS, base_node, extra_fragment) {
1378                         Ok(res) => {
1379                             debug!("got res in TypeNS: {:?}", res);
1380                             Ok(res)
1381                         }
1382                         Err(ErrorKind::AnchorFailure(msg)) => {
1383                             anchor_failure(
1384                                 self.cx,
1385                                 diag.item,
1386                                 diag.ori_link,
1387                                 diag.dox,
1388                                 diag.link_range,
1389                                 msg,
1390                             );
1391                             return None;
1392                         }
1393                         Err(ErrorKind::Resolve(box kind)) => Err(kind),
1394                     },
1395                     value_ns: match self.resolve(path_str, ValueNS, base_node, extra_fragment) {
1396                         Ok(res) => Ok(res),
1397                         Err(ErrorKind::AnchorFailure(msg)) => {
1398                             anchor_failure(
1399                                 self.cx,
1400                                 diag.item,
1401                                 diag.ori_link,
1402                                 diag.dox,
1403                                 diag.link_range,
1404                                 msg,
1405                             );
1406                             return None;
1407                         }
1408                         Err(ErrorKind::Resolve(box kind)) => Err(kind),
1409                     }
1410                     .and_then(|(res, fragment)| {
1411                         // Constructors are picked up in the type namespace.
1412                         match res {
1413                             Res::Def(DefKind::Ctor(..), _) => {
1414                                 Err(ResolutionFailure::WrongNamespace { res, expected_ns: TypeNS })
1415                             }
1416                             _ => {
1417                                 match (fragment, extra_fragment.clone()) {
1418                                     (Some(fragment), Some(_)) => {
1419                                         // Shouldn't happen but who knows?
1420                                         Ok((res, Some(fragment)))
1421                                     }
1422                                     (fragment, None) | (None, fragment) => Ok((res, fragment)),
1423                                 }
1424                             }
1425                         }
1426                     }),
1427                 };
1428
1429                 let len = candidates.iter().filter(|res| res.is_ok()).count();
1430
1431                 if len == 0 {
1432                     resolution_failure(
1433                         self,
1434                         diag.item,
1435                         path_str,
1436                         disambiguator,
1437                         diag.dox,
1438                         diag.link_range,
1439                         candidates.into_iter().filter_map(|res| res.err()).collect(),
1440                     );
1441                     // this could just be a normal link
1442                     return None;
1443                 }
1444
1445                 if len == 1 {
1446                     Some(candidates.into_iter().filter_map(|res| res.ok()).next().unwrap())
1447                 } else if len == 2 && is_derive_trait_collision(&candidates) {
1448                     Some(candidates.type_ns.unwrap())
1449                 } else {
1450                     if is_derive_trait_collision(&candidates) {
1451                         candidates.macro_ns = Err(ResolutionFailure::Dummy);
1452                     }
1453                     // If we're reporting an ambiguity, don't mention the namespaces that failed
1454                     let candidates = candidates.map(|candidate| candidate.ok().map(|(res, _)| res));
1455                     ambiguity_error(
1456                         self.cx,
1457                         diag.item,
1458                         path_str,
1459                         diag.dox,
1460                         diag.link_range,
1461                         candidates.present_items().collect(),
1462                     );
1463                     None
1464                 }
1465             }
1466             Some(MacroNS) => {
1467                 match self.resolve_macro(path_str, base_node) {
1468                     Ok(res) => Some((res, extra_fragment.clone())),
1469                     Err(mut kind) => {
1470                         // `resolve_macro` only looks in the macro namespace. Try to give a better error if possible.
1471                         for &ns in &[TypeNS, ValueNS] {
1472                             if let Some(res) =
1473                                 self.check_full_res(ns, path_str, base_node, extra_fragment)
1474                             {
1475                                 kind =
1476                                     ResolutionFailure::WrongNamespace { res, expected_ns: MacroNS };
1477                                 break;
1478                             }
1479                         }
1480                         resolution_failure(
1481                             self,
1482                             diag.item,
1483                             path_str,
1484                             disambiguator,
1485                             diag.dox,
1486                             diag.link_range,
1487                             smallvec![kind],
1488                         );
1489                         None
1490                     }
1491                 }
1492             }
1493         }
1494     }
1495 }
1496
1497 /// Get the section of a link between the backticks,
1498 /// or the whole link if there aren't any backticks.
1499 ///
1500 /// For example:
1501 ///
1502 /// ```text
1503 /// [`Foo`]
1504 ///   ^^^
1505 /// ```
1506 fn range_between_backticks(ori_link: &MarkdownLink) -> Range<usize> {
1507     let after_first_backtick_group = ori_link.link.bytes().position(|b| b != b'`').unwrap_or(0);
1508     let before_second_backtick_group = ori_link
1509         .link
1510         .bytes()
1511         .skip(after_first_backtick_group)
1512         .position(|b| b == b'`')
1513         .unwrap_or(ori_link.link.len());
1514     (ori_link.range.start + after_first_backtick_group)
1515         ..(ori_link.range.start + before_second_backtick_group)
1516 }
1517
1518 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1519 /// Disambiguators for a link.
1520 crate enum Disambiguator {
1521     /// `prim@`
1522     ///
1523     /// This is buggy, see <https://github.com/rust-lang/rust/pull/77875#discussion_r503583103>
1524     Primitive,
1525     /// `struct@` or `f()`
1526     Kind(DefKind),
1527     /// `type@`
1528     Namespace(Namespace),
1529 }
1530
1531 impl Disambiguator {
1532     /// The text that should be displayed when the path is rendered as HTML.
1533     ///
1534     /// NOTE: `path` is not the original link given by the user, but a name suitable for passing to `resolve`.
1535     fn display_for(&self, path: &str) -> String {
1536         match self {
1537             // FIXME: this will have different output if the user had `m!()` originally.
1538             Self::Kind(DefKind::Macro(MacroKind::Bang)) => format!("{}!", path),
1539             Self::Kind(DefKind::Fn) => format!("{}()", path),
1540             _ => path.to_owned(),
1541         }
1542     }
1543
1544     /// Given a link, parse and return `(disambiguator, path_str)`.
1545     ///
1546     /// This returns `Ok(Some(...))` if a disambiguator was found,
1547     /// `Ok(None)` if no disambiguator was found, or `Err(...)`
1548     /// if there was a problem with the disambiguator.
1549     crate fn from_str(link: &str) -> Result<Option<(Self, &str)>, (String, Range<usize>)> {
1550         use Disambiguator::{Kind, Namespace as NS, Primitive};
1551
1552         if let Some(idx) = link.find('@') {
1553             let (prefix, rest) = link.split_at(idx);
1554             let d = match prefix {
1555                 "struct" => Kind(DefKind::Struct),
1556                 "enum" => Kind(DefKind::Enum),
1557                 "trait" => Kind(DefKind::Trait),
1558                 "union" => Kind(DefKind::Union),
1559                 "module" | "mod" => Kind(DefKind::Mod),
1560                 "const" | "constant" => Kind(DefKind::Const),
1561                 "static" => Kind(DefKind::Static),
1562                 "function" | "fn" | "method" => Kind(DefKind::Fn),
1563                 "derive" => Kind(DefKind::Macro(MacroKind::Derive)),
1564                 "type" => NS(Namespace::TypeNS),
1565                 "value" => NS(Namespace::ValueNS),
1566                 "macro" => NS(Namespace::MacroNS),
1567                 "prim" | "primitive" => Primitive,
1568                 _ => return Err((format!("unknown disambiguator `{}`", prefix), 0..idx)),
1569             };
1570             Ok(Some((d, &rest[1..])))
1571         } else {
1572             let suffixes = [
1573                 ("!()", DefKind::Macro(MacroKind::Bang)),
1574                 ("()", DefKind::Fn),
1575                 ("!", DefKind::Macro(MacroKind::Bang)),
1576             ];
1577             for &(suffix, kind) in &suffixes {
1578                 if let Some(link) = link.strip_suffix(suffix) {
1579                     // Avoid turning `!` or `()` into an empty string
1580                     if !link.is_empty() {
1581                         return Ok(Some((Kind(kind), link)));
1582                     }
1583                 }
1584             }
1585             Ok(None)
1586         }
1587     }
1588
1589     fn from_res(res: Res) -> Self {
1590         match res {
1591             Res::Def(kind, _) => Disambiguator::Kind(kind),
1592             Res::Primitive(_) => Disambiguator::Primitive,
1593         }
1594     }
1595
1596     /// Used for error reporting.
1597     fn suggestion(self) -> Suggestion {
1598         let kind = match self {
1599             Disambiguator::Primitive => return Suggestion::Prefix("prim"),
1600             Disambiguator::Kind(kind) => kind,
1601             Disambiguator::Namespace(_) => panic!("display_for cannot be used on namespaces"),
1602         };
1603         if kind == DefKind::Macro(MacroKind::Bang) {
1604             return Suggestion::Macro;
1605         } else if kind == DefKind::Fn || kind == DefKind::AssocFn {
1606             return Suggestion::Function;
1607         }
1608
1609         let prefix = match kind {
1610             DefKind::Struct => "struct",
1611             DefKind::Enum => "enum",
1612             DefKind::Trait => "trait",
1613             DefKind::Union => "union",
1614             DefKind::Mod => "mod",
1615             DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst => {
1616                 "const"
1617             }
1618             DefKind::Static => "static",
1619             DefKind::Macro(MacroKind::Derive) => "derive",
1620             // Now handle things that don't have a specific disambiguator
1621             _ => match kind
1622                 .ns()
1623                 .expect("tried to calculate a disambiguator for a def without a namespace?")
1624             {
1625                 Namespace::TypeNS => "type",
1626                 Namespace::ValueNS => "value",
1627                 Namespace::MacroNS => "macro",
1628             },
1629         };
1630
1631         Suggestion::Prefix(prefix)
1632     }
1633
1634     fn ns(self) -> Namespace {
1635         match self {
1636             Self::Namespace(n) => n,
1637             Self::Kind(k) => {
1638                 k.ns().expect("only DefKinds with a valid namespace can be disambiguators")
1639             }
1640             Self::Primitive => TypeNS,
1641         }
1642     }
1643
1644     fn article(self) -> &'static str {
1645         match self {
1646             Self::Namespace(_) => panic!("article() doesn't make sense for namespaces"),
1647             Self::Kind(k) => k.article(),
1648             Self::Primitive => "a",
1649         }
1650     }
1651
1652     fn descr(self) -> &'static str {
1653         match self {
1654             Self::Namespace(n) => n.descr(),
1655             // HACK(jynelson): by looking at the source I saw the DefId we pass
1656             // for `expected.descr()` doesn't matter, since it's not a crate
1657             Self::Kind(k) => k.descr(DefId::local(hir::def_id::DefIndex::from_usize(0))),
1658             Self::Primitive => "builtin type",
1659         }
1660     }
1661 }
1662
1663 /// A suggestion to show in a diagnostic.
1664 enum Suggestion {
1665     /// `struct@`
1666     Prefix(&'static str),
1667     /// `f()`
1668     Function,
1669     /// `m!`
1670     Macro,
1671 }
1672
1673 impl Suggestion {
1674     fn descr(&self) -> Cow<'static, str> {
1675         match self {
1676             Self::Prefix(x) => format!("prefix with `{}@`", x).into(),
1677             Self::Function => "add parentheses".into(),
1678             Self::Macro => "add an exclamation mark".into(),
1679         }
1680     }
1681
1682     fn as_help(&self, path_str: &str) -> String {
1683         // FIXME: if this is an implied shortcut link, it's bad style to suggest `@`
1684         match self {
1685             Self::Prefix(prefix) => format!("{}@{}", prefix, path_str),
1686             Self::Function => format!("{}()", path_str),
1687             Self::Macro => format!("{}!", path_str),
1688         }
1689     }
1690 }
1691
1692 /// Reports a diagnostic for an intra-doc link.
1693 ///
1694 /// If no link range is provided, or the source span of the link cannot be determined, the span of
1695 /// the entire documentation block is used for the lint. If a range is provided but the span
1696 /// calculation fails, a note is added to the diagnostic pointing to the link in the markdown.
1697 ///
1698 /// The `decorate` callback is invoked in all cases to allow further customization of the
1699 /// diagnostic before emission. If the span of the link was able to be determined, the second
1700 /// parameter of the callback will contain it, and the primary span of the diagnostic will be set
1701 /// to it.
1702 fn report_diagnostic(
1703     tcx: TyCtxt<'_>,
1704     lint: &'static Lint,
1705     msg: &str,
1706     item: &Item,
1707     dox: &str,
1708     link_range: &Range<usize>,
1709     decorate: impl FnOnce(&mut DiagnosticBuilder<'_>, Option<rustc_span::Span>),
1710 ) {
1711     let hir_id = match DocContext::as_local_hir_id(tcx, item.def_id) {
1712         Some(hir_id) => hir_id,
1713         None => {
1714             // If non-local, no need to check anything.
1715             info!("ignoring warning from parent crate: {}", msg);
1716             return;
1717         }
1718     };
1719
1720     let attrs = &item.attrs;
1721     let sp = span_of_attrs(attrs).unwrap_or(item.span.inner());
1722
1723     tcx.struct_span_lint_hir(lint, hir_id, sp, |lint| {
1724         let mut diag = lint.build(msg);
1725
1726         let span = super::source_span_for_markdown_range(tcx, dox, link_range, attrs);
1727
1728         if let Some(sp) = span {
1729             diag.set_span(sp);
1730         } else {
1731             // blah blah blah\nblah\nblah [blah] blah blah\nblah blah
1732             //                       ^     ~~~~
1733             //                       |     link_range
1734             //                       last_new_line_offset
1735             let last_new_line_offset = dox[..link_range.start].rfind('\n').map_or(0, |n| n + 1);
1736             let line = dox[last_new_line_offset..].lines().next().unwrap_or("");
1737
1738             // Print the line containing the `link_range` and manually mark it with '^'s.
1739             diag.note(&format!(
1740                 "the link appears in this line:\n\n{line}\n\
1741                      {indicator: <before$}{indicator:^<found$}",
1742                 line = line,
1743                 indicator = "",
1744                 before = link_range.start - last_new_line_offset,
1745                 found = link_range.len(),
1746             ));
1747         }
1748
1749         decorate(&mut diag, span);
1750
1751         diag.emit();
1752     });
1753 }
1754
1755 /// Reports a link that failed to resolve.
1756 ///
1757 /// This also tries to resolve any intermediate path segments that weren't
1758 /// handled earlier. For example, if passed `Item::Crate(std)` and `path_str`
1759 /// `std::io::Error::x`, this will resolve `std::io::Error`.
1760 fn resolution_failure(
1761     collector: &mut LinkCollector<'_, '_>,
1762     item: &Item,
1763     path_str: &str,
1764     disambiguator: Option<Disambiguator>,
1765     dox: &str,
1766     link_range: Range<usize>,
1767     kinds: SmallVec<[ResolutionFailure<'_>; 3]>,
1768 ) {
1769     let tcx = collector.cx.tcx;
1770     report_diagnostic(
1771         tcx,
1772         BROKEN_INTRA_DOC_LINKS,
1773         &format!("unresolved link to `{}`", path_str),
1774         item,
1775         dox,
1776         &link_range,
1777         |diag, sp| {
1778             let item = |res: Res| format!("the {} `{}`", res.descr(), res.name(tcx),);
1779             let assoc_item_not_allowed = |res: Res| {
1780                 let name = res.name(tcx);
1781                 format!(
1782                     "`{}` is {} {}, not a module or type, and cannot have associated items",
1783                     name,
1784                     res.article(),
1785                     res.descr()
1786                 )
1787             };
1788             // ignore duplicates
1789             let mut variants_seen = SmallVec::<[_; 3]>::new();
1790             for mut failure in kinds {
1791                 let variant = std::mem::discriminant(&failure);
1792                 if variants_seen.contains(&variant) {
1793                     continue;
1794                 }
1795                 variants_seen.push(variant);
1796
1797                 if let ResolutionFailure::NotResolved { module_id, partial_res, unresolved } =
1798                     &mut failure
1799                 {
1800                     use DefKind::*;
1801
1802                     let module_id = *module_id;
1803                     // FIXME(jynelson): this might conflict with my `Self` fix in #76467
1804                     // FIXME: maybe use itertools `collect_tuple` instead?
1805                     fn split(path: &str) -> Option<(&str, &str)> {
1806                         let mut splitter = path.rsplitn(2, "::");
1807                         splitter.next().and_then(|right| splitter.next().map(|left| (left, right)))
1808                     }
1809
1810                     // Check if _any_ parent of the path gets resolved.
1811                     // If so, report it and say the first which failed; if not, say the first path segment didn't resolve.
1812                     let mut name = path_str;
1813                     'outer: loop {
1814                         let (start, end) = if let Some(x) = split(name) {
1815                             x
1816                         } else {
1817                             // avoid bug that marked [Quux::Z] as missing Z, not Quux
1818                             if partial_res.is_none() {
1819                                 *unresolved = name.into();
1820                             }
1821                             break;
1822                         };
1823                         name = start;
1824                         for &ns in &[TypeNS, ValueNS, MacroNS] {
1825                             if let Some(res) =
1826                                 collector.check_full_res(ns, &start, module_id, &None)
1827                             {
1828                                 debug!("found partial_res={:?}", res);
1829                                 *partial_res = Some(res);
1830                                 *unresolved = end.into();
1831                                 break 'outer;
1832                             }
1833                         }
1834                         *unresolved = end.into();
1835                     }
1836
1837                     let last_found_module = match *partial_res {
1838                         Some(Res::Def(DefKind::Mod, id)) => Some(id),
1839                         None => Some(module_id),
1840                         _ => None,
1841                     };
1842                     // See if this was a module: `[path]` or `[std::io::nope]`
1843                     if let Some(module) = last_found_module {
1844                         let note = if partial_res.is_some() {
1845                             // Part of the link resolved; e.g. `std::io::nonexistent`
1846                             let module_name = tcx.item_name(module);
1847                             format!("no item named `{}` in module `{}`", unresolved, module_name)
1848                         } else {
1849                             // None of the link resolved; e.g. `Notimported`
1850                             format!("no item named `{}` in scope", unresolved)
1851                         };
1852                         if let Some(span) = sp {
1853                             diag.span_label(span, &note);
1854                         } else {
1855                             diag.note(&note);
1856                         }
1857
1858                         // If the link has `::` in it, assume it was meant to be an intra-doc link.
1859                         // Otherwise, the `[]` might be unrelated.
1860                         // FIXME: don't show this for autolinks (`<>`), `()` style links, or reference links
1861                         if !path_str.contains("::") {
1862                             diag.help(r#"to escape `[` and `]` characters, add '\' before them like `\[` or `\]`"#);
1863                         }
1864
1865                         continue;
1866                     }
1867
1868                     // Otherwise, it must be an associated item or variant
1869                     let res = partial_res.expect("None case was handled by `last_found_module`");
1870                     let name = res.name(tcx);
1871                     let kind = match res {
1872                         Res::Def(kind, _) => Some(kind),
1873                         Res::Primitive(_) => None,
1874                     };
1875                     let path_description = if let Some(kind) = kind {
1876                         match kind {
1877                             Mod | ForeignMod => "inner item",
1878                             Struct => "field or associated item",
1879                             Enum | Union => "variant or associated item",
1880                             Variant
1881                             | Field
1882                             | Closure
1883                             | Generator
1884                             | AssocTy
1885                             | AssocConst
1886                             | AssocFn
1887                             | Fn
1888                             | Macro(_)
1889                             | Const
1890                             | ConstParam
1891                             | ExternCrate
1892                             | Use
1893                             | LifetimeParam
1894                             | Ctor(_, _)
1895                             | AnonConst => {
1896                                 let note = assoc_item_not_allowed(res);
1897                                 if let Some(span) = sp {
1898                                     diag.span_label(span, &note);
1899                                 } else {
1900                                     diag.note(&note);
1901                                 }
1902                                 return;
1903                             }
1904                             Trait | TyAlias | ForeignTy | OpaqueTy | TraitAlias | TyParam
1905                             | Static => "associated item",
1906                             Impl | GlobalAsm => unreachable!("not a path"),
1907                         }
1908                     } else {
1909                         "associated item"
1910                     };
1911                     let note = format!(
1912                         "the {} `{}` has no {} named `{}`",
1913                         res.descr(),
1914                         name,
1915                         disambiguator.map_or(path_description, |d| d.descr()),
1916                         unresolved,
1917                     );
1918                     if let Some(span) = sp {
1919                         diag.span_label(span, &note);
1920                     } else {
1921                         diag.note(&note);
1922                     }
1923
1924                     continue;
1925                 }
1926                 let note = match failure {
1927                     ResolutionFailure::NotResolved { .. } => unreachable!("handled above"),
1928                     ResolutionFailure::Dummy => continue,
1929                     ResolutionFailure::WrongNamespace { res, expected_ns } => {
1930                         if let Res::Def(kind, _) = res {
1931                             let disambiguator = Disambiguator::Kind(kind);
1932                             suggest_disambiguator(
1933                                 disambiguator,
1934                                 diag,
1935                                 path_str,
1936                                 dox,
1937                                 sp,
1938                                 &link_range,
1939                             )
1940                         }
1941
1942                         format!(
1943                             "this link resolves to {}, which is not in the {} namespace",
1944                             item(res),
1945                             expected_ns.descr()
1946                         )
1947                     }
1948                     ResolutionFailure::NoParentItem => {
1949                         diag.level = rustc_errors::Level::Bug;
1950                         "all intra-doc links should have a parent item".to_owned()
1951                     }
1952                     ResolutionFailure::MalformedGenerics(variant) => match variant {
1953                         MalformedGenerics::UnbalancedAngleBrackets => {
1954                             String::from("unbalanced angle brackets")
1955                         }
1956                         MalformedGenerics::MissingType => {
1957                             String::from("missing type for generic parameters")
1958                         }
1959                         MalformedGenerics::HasFullyQualifiedSyntax => {
1960                             diag.note("see https://github.com/rust-lang/rust/issues/74563 for more information");
1961                             String::from("fully-qualified syntax is unsupported")
1962                         }
1963                         MalformedGenerics::InvalidPathSeparator => {
1964                             String::from("has invalid path separator")
1965                         }
1966                         MalformedGenerics::TooManyAngleBrackets => {
1967                             String::from("too many angle brackets")
1968                         }
1969                         MalformedGenerics::EmptyAngleBrackets => {
1970                             String::from("empty angle brackets")
1971                         }
1972                     },
1973                 };
1974                 if let Some(span) = sp {
1975                     diag.span_label(span, &note);
1976                 } else {
1977                     diag.note(&note);
1978                 }
1979             }
1980         },
1981     );
1982 }
1983
1984 /// Report an anchor failure.
1985 fn anchor_failure(
1986     cx: &DocContext<'_>,
1987     item: &Item,
1988     path_str: &str,
1989     dox: &str,
1990     link_range: Range<usize>,
1991     failure: AnchorFailure,
1992 ) {
1993     let msg = match failure {
1994         AnchorFailure::MultipleAnchors => format!("`{}` contains multiple anchors", path_str),
1995         AnchorFailure::RustdocAnchorConflict(res) => format!(
1996             "`{}` contains an anchor, but links to {kind}s are already anchored",
1997             path_str,
1998             kind = res.descr(),
1999         ),
2000     };
2001
2002     report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, &msg, item, dox, &link_range, |diag, sp| {
2003         if let Some(sp) = sp {
2004             diag.span_label(sp, "contains invalid anchor");
2005         }
2006     });
2007 }
2008
2009 /// Report an error in the link disambiguator.
2010 fn disambiguator_error(
2011     cx: &DocContext<'_>,
2012     item: &Item,
2013     dox: &str,
2014     link_range: Range<usize>,
2015     msg: &str,
2016 ) {
2017     report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, msg, item, dox, &link_range, |_diag, _sp| {});
2018 }
2019
2020 /// Report an ambiguity error, where there were multiple possible resolutions.
2021 fn ambiguity_error(
2022     cx: &DocContext<'_>,
2023     item: &Item,
2024     path_str: &str,
2025     dox: &str,
2026     link_range: Range<usize>,
2027     candidates: Vec<Res>,
2028 ) {
2029     let mut msg = format!("`{}` is ", path_str);
2030
2031     match candidates.as_slice() {
2032         [first_def, second_def] => {
2033             msg += &format!(
2034                 "both {} {} and {} {}",
2035                 first_def.article(),
2036                 first_def.descr(),
2037                 second_def.article(),
2038                 second_def.descr(),
2039             );
2040         }
2041         _ => {
2042             let mut candidates = candidates.iter().peekable();
2043             while let Some(res) = candidates.next() {
2044                 if candidates.peek().is_some() {
2045                     msg += &format!("{} {}, ", res.article(), res.descr());
2046                 } else {
2047                     msg += &format!("and {} {}", res.article(), res.descr());
2048                 }
2049             }
2050         }
2051     }
2052
2053     report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, &msg, item, dox, &link_range, |diag, sp| {
2054         if let Some(sp) = sp {
2055             diag.span_label(sp, "ambiguous link");
2056         } else {
2057             diag.note("ambiguous link");
2058         }
2059
2060         for res in candidates {
2061             let disambiguator = Disambiguator::from_res(res);
2062             suggest_disambiguator(disambiguator, diag, path_str, dox, sp, &link_range);
2063         }
2064     });
2065 }
2066
2067 /// In case of an ambiguity or mismatched disambiguator, suggest the correct
2068 /// disambiguator.
2069 fn suggest_disambiguator(
2070     disambiguator: Disambiguator,
2071     diag: &mut DiagnosticBuilder<'_>,
2072     path_str: &str,
2073     dox: &str,
2074     sp: Option<rustc_span::Span>,
2075     link_range: &Range<usize>,
2076 ) {
2077     let suggestion = disambiguator.suggestion();
2078     let help = format!("to link to the {}, {}", disambiguator.descr(), suggestion.descr());
2079
2080     if let Some(sp) = sp {
2081         let msg = if dox.bytes().nth(link_range.start) == Some(b'`') {
2082             format!("`{}`", suggestion.as_help(path_str))
2083         } else {
2084             suggestion.as_help(path_str)
2085         };
2086
2087         diag.span_suggestion(sp, &help, msg, Applicability::MaybeIncorrect);
2088     } else {
2089         diag.help(&format!("{}: {}", help, suggestion.as_help(path_str)));
2090     }
2091 }
2092
2093 /// Report a link from a public item to a private one.
2094 fn privacy_error(cx: &DocContext<'_>, item: &Item, path_str: &str, dox: &str, link: &MarkdownLink) {
2095     let sym;
2096     let item_name = match item.name {
2097         Some(name) => {
2098             sym = name.as_str();
2099             &*sym
2100         }
2101         None => "<unknown>",
2102     };
2103     let msg =
2104         format!("public documentation for `{}` links to private item `{}`", item_name, path_str);
2105
2106     report_diagnostic(cx.tcx, PRIVATE_INTRA_DOC_LINKS, &msg, item, dox, &link.range, |diag, sp| {
2107         if let Some(sp) = sp {
2108             diag.span_label(sp, "this item is private");
2109         }
2110
2111         let note_msg = if cx.render_options.document_private {
2112             "this link resolves only because you passed `--document-private-items`, but will break without"
2113         } else {
2114             "this link will resolve properly if you pass `--document-private-items`"
2115         };
2116         diag.note(note_msg);
2117     });
2118 }
2119
2120 /// Given an enum variant's res, return the res of its enum and the associated fragment.
2121 fn handle_variant(
2122     cx: &DocContext<'_>,
2123     res: Res,
2124     extra_fragment: &Option<String>,
2125 ) -> Result<(Res, Option<String>), ErrorKind<'static>> {
2126     use rustc_middle::ty::DefIdTree;
2127
2128     if extra_fragment.is_some() {
2129         return Err(ErrorKind::AnchorFailure(AnchorFailure::RustdocAnchorConflict(res)));
2130     }
2131     cx.tcx
2132         .parent(res.def_id())
2133         .map(|parent| {
2134             let parent_def = Res::Def(DefKind::Enum, parent);
2135             let variant = cx.tcx.expect_variant_res(res.as_hir_res().unwrap());
2136             (parent_def, Some(format!("variant.{}", variant.ident.name)))
2137         })
2138         .ok_or_else(|| ResolutionFailure::NoParentItem.into())
2139 }
2140
2141 /// Resolve a primitive type or value.
2142 fn resolve_primitive(path_str: &str, ns: Namespace) -> Option<Res> {
2143     if ns != TypeNS {
2144         return None;
2145     }
2146     use PrimitiveType::*;
2147     let prim = match path_str {
2148         "isize" => Isize,
2149         "i8" => I8,
2150         "i16" => I16,
2151         "i32" => I32,
2152         "i64" => I64,
2153         "i128" => I128,
2154         "usize" => Usize,
2155         "u8" => U8,
2156         "u16" => U16,
2157         "u32" => U32,
2158         "u64" => U64,
2159         "u128" => U128,
2160         "f32" => F32,
2161         "f64" => F64,
2162         "char" => Char,
2163         "bool" | "true" | "false" => Bool,
2164         "str" | "&str" => Str,
2165         // See #80181 for why these don't have symbols associated.
2166         "slice" => Slice,
2167         "array" => Array,
2168         "tuple" => Tuple,
2169         "unit" => Unit,
2170         "pointer" | "*const" | "*mut" => RawPointer,
2171         "reference" | "&" | "&mut" => Reference,
2172         "fn" => Fn,
2173         "never" | "!" => Never,
2174         _ => return None,
2175     };
2176     debug!("resolved primitives {:?}", prim);
2177     Some(Res::Primitive(prim))
2178 }
2179
2180 fn strip_generics_from_path(path_str: &str) -> Result<String, ResolutionFailure<'static>> {
2181     let mut stripped_segments = vec![];
2182     let mut path = path_str.chars().peekable();
2183     let mut segment = Vec::new();
2184
2185     while let Some(chr) = path.next() {
2186         match chr {
2187             ':' => {
2188                 if path.next_if_eq(&':').is_some() {
2189                     let stripped_segment =
2190                         strip_generics_from_path_segment(mem::take(&mut segment))?;
2191                     if !stripped_segment.is_empty() {
2192                         stripped_segments.push(stripped_segment);
2193                     }
2194                 } else {
2195                     return Err(ResolutionFailure::MalformedGenerics(
2196                         MalformedGenerics::InvalidPathSeparator,
2197                     ));
2198                 }
2199             }
2200             '<' => {
2201                 segment.push(chr);
2202
2203                 match path.next() {
2204                     Some('<') => {
2205                         return Err(ResolutionFailure::MalformedGenerics(
2206                             MalformedGenerics::TooManyAngleBrackets,
2207                         ));
2208                     }
2209                     Some('>') => {
2210                         return Err(ResolutionFailure::MalformedGenerics(
2211                             MalformedGenerics::EmptyAngleBrackets,
2212                         ));
2213                     }
2214                     Some(chr) => {
2215                         segment.push(chr);
2216
2217                         while let Some(chr) = path.next_if(|c| *c != '>') {
2218                             segment.push(chr);
2219                         }
2220                     }
2221                     None => break,
2222                 }
2223             }
2224             _ => segment.push(chr),
2225         }
2226         trace!("raw segment: {:?}", segment);
2227     }
2228
2229     if !segment.is_empty() {
2230         let stripped_segment = strip_generics_from_path_segment(segment)?;
2231         if !stripped_segment.is_empty() {
2232             stripped_segments.push(stripped_segment);
2233         }
2234     }
2235
2236     debug!("path_str: {:?}\nstripped segments: {:?}", path_str, &stripped_segments);
2237
2238     let stripped_path = stripped_segments.join("::");
2239
2240     if !stripped_path.is_empty() {
2241         Ok(stripped_path)
2242     } else {
2243         Err(ResolutionFailure::MalformedGenerics(MalformedGenerics::MissingType))
2244     }
2245 }
2246
2247 fn strip_generics_from_path_segment(
2248     segment: Vec<char>,
2249 ) -> Result<String, ResolutionFailure<'static>> {
2250     let mut stripped_segment = String::new();
2251     let mut param_depth = 0;
2252
2253     let mut latest_generics_chunk = String::new();
2254
2255     for c in segment {
2256         if c == '<' {
2257             param_depth += 1;
2258             latest_generics_chunk.clear();
2259         } else if c == '>' {
2260             param_depth -= 1;
2261             if latest_generics_chunk.contains(" as ") {
2262                 // The segment tries to use fully-qualified syntax, which is currently unsupported.
2263                 // Give a helpful error message instead of completely ignoring the angle brackets.
2264                 return Err(ResolutionFailure::MalformedGenerics(
2265                     MalformedGenerics::HasFullyQualifiedSyntax,
2266                 ));
2267             }
2268         } else {
2269             if param_depth == 0 {
2270                 stripped_segment.push(c);
2271             } else {
2272                 latest_generics_chunk.push(c);
2273             }
2274         }
2275     }
2276
2277     if param_depth == 0 {
2278         Ok(stripped_segment)
2279     } else {
2280         // The segment has unbalanced angle brackets, e.g. `Vec<T` or `Vec<T>>`
2281         Err(ResolutionFailure::MalformedGenerics(MalformedGenerics::UnbalancedAngleBrackets))
2282     }
2283 }