1 //! This module implements [RFC 1946]: Intra-rustdoc-links
3 //! [RFC 1946]: https://github.com/rust-lang/rfcs/blob/master/text/1946-intra-rustdoc-links.md
5 use pulldown_cmark::LinkType;
6 use rustc_data_structures::{fx::FxHashMap, intern::Interned, stable_set::FxHashSet};
7 use rustc_errors::{Applicability, Diagnostic};
8 use rustc_hir::def::Namespace::*;
9 use rustc_hir::def::{DefKind, Namespace, PerNS};
10 use rustc_hir::def_id::{DefId, CRATE_DEF_ID};
11 use rustc_hir::Mutability;
12 use rustc_middle::ty::{DefIdTree, Ty, TyCtxt};
13 use rustc_middle::{bug, span_bug, ty};
14 use rustc_session::lint::Lint;
15 use rustc_span::hygiene::MacroKind;
16 use rustc_span::symbol::{sym, Ident, Symbol};
17 use rustc_span::{BytePos, DUMMY_SP};
18 use smallvec::{smallvec, SmallVec};
25 use crate::clean::{self, utils::find_nearest_parent_module};
26 use crate::clean::{Crate, Item, ItemId, ItemLink, PrimitiveType};
27 use crate::core::DocContext;
28 use crate::html::markdown::{markdown_links, MarkdownLink};
29 use crate::lint::{BROKEN_INTRA_DOC_LINKS, PRIVATE_INTRA_DOC_LINKS};
30 use crate::passes::Pass;
31 use crate::visit::DocVisitor;
34 crate use early::early_resolve_intra_doc_links;
36 crate const COLLECT_INTRA_DOC_LINKS: Pass = Pass {
37 name: "collect-intra-doc-links",
38 run: collect_intra_doc_links,
39 description: "resolves intra-doc links",
42 fn collect_intra_doc_links(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
44 LinkCollector { cx, mod_ids: Vec::new(), visited_links: FxHashMap::default() };
45 collector.visit_crate(&krate);
49 /// Top-level errors emitted by this pass.
51 Resolve(Box<ResolutionFailure<'a>>),
52 AnchorFailure(AnchorFailure),
55 impl<'a> From<ResolutionFailure<'a>> for ErrorKind<'a> {
56 fn from(err: ResolutionFailure<'a>) -> Self {
57 ErrorKind::Resolve(box err)
61 #[derive(Copy, Clone, Debug, Hash)]
64 Primitive(PrimitiveType),
67 type ResolveRes = rustc_hir::def::Res<rustc_ast::NodeId>;
70 fn descr(self) -> &'static str {
72 Res::Def(kind, id) => ResolveRes::Def(kind, id).descr(),
73 Res::Primitive(_) => "builtin type",
77 fn article(self) -> &'static str {
79 Res::Def(kind, id) => ResolveRes::Def(kind, id).article(),
80 Res::Primitive(_) => "a",
84 fn name(self, tcx: TyCtxt<'_>) -> Symbol {
86 Res::Def(_, id) => tcx.item_name(id),
87 Res::Primitive(prim) => prim.as_sym(),
91 fn def_id(self, tcx: TyCtxt<'_>) -> DefId {
93 Res::Def(_, id) => id,
94 Res::Primitive(prim) => *PrimitiveType::primitive_locations(tcx).get(&prim).unwrap(),
98 fn as_hir_res(self) -> Option<rustc_hir::def::Res> {
100 Res::Def(kind, id) => Some(rustc_hir::def::Res::Def(kind, id)),
101 // FIXME: maybe this should handle the subset of PrimitiveType that fits into hir::PrimTy?
102 Res::Primitive(_) => None,
106 /// Used for error reporting.
107 fn disambiguator_suggestion(self) -> Suggestion {
108 let kind = match self {
109 Res::Primitive(_) => return Suggestion::Prefix("prim"),
110 Res::Def(kind, _) => kind,
112 if kind == DefKind::Macro(MacroKind::Bang) {
113 return Suggestion::Macro;
114 } else if kind == DefKind::Fn || kind == DefKind::AssocFn {
115 return Suggestion::Function;
116 } else if kind == DefKind::Field {
117 return Suggestion::RemoveDisambiguator;
120 let prefix = match kind {
121 DefKind::Struct => "struct",
122 DefKind::Enum => "enum",
123 DefKind::Trait => "trait",
124 DefKind::Union => "union",
125 DefKind::Mod => "mod",
126 DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst => {
129 DefKind::Static(_) => "static",
130 DefKind::Macro(MacroKind::Derive) => "derive",
131 // Now handle things that don't have a specific disambiguator
134 .expect("tried to calculate a disambiguator for a def without a namespace?")
136 Namespace::TypeNS => "type",
137 Namespace::ValueNS => "value",
138 Namespace::MacroNS => "macro",
142 Suggestion::Prefix(prefix)
146 impl TryFrom<ResolveRes> for Res {
149 fn try_from(res: ResolveRes) -> Result<Self, ()> {
150 use rustc_hir::def::Res::*;
152 Def(kind, id) => Ok(Res::Def(kind, id)),
153 PrimTy(prim) => Ok(Res::Primitive(PrimitiveType::from_hir(prim))),
155 NonMacroAttr(..) | Err => Result::Err(()),
156 other => bug!("unrecognized res {:?}", other),
161 /// A link failed to resolve.
163 enum ResolutionFailure<'a> {
164 /// This resolved, but with the wrong namespace.
166 /// What the link resolved to.
168 /// The expected namespace for the resolution, determined from the link's disambiguator.
170 /// E.g., for `[fn@Result]` this is [`Namespace::ValueNS`],
171 /// even though `Result`'s actual namespace is [`Namespace::TypeNS`].
172 expected_ns: Namespace,
174 /// The link failed to resolve. [`resolution_failure`] should look to see if there's
175 /// a more helpful error that can be given.
177 /// Item on which the link is resolved, used for resolving `Self`.
179 /// The scope the link was resolved in.
181 /// If part of the link resolved, this has the `Res`.
183 /// In `[std::io::Error::x]`, `std::io::Error` would be a partial resolution.
184 partial_res: Option<Res>,
185 /// The remaining unresolved path segments.
187 /// In `[std::io::Error::x]`, `x` would be unresolved.
188 unresolved: Cow<'a, str>,
190 /// This happens when rustdoc can't determine the parent scope for an item.
191 /// It is always a bug in rustdoc.
193 /// This link has malformed generic parameters; e.g., the angle brackets are unbalanced.
194 MalformedGenerics(MalformedGenerics),
195 /// Used to communicate that this should be ignored, but shouldn't be reported to the user.
197 /// This happens when there is no disambiguator and one of the namespaces
198 /// failed to resolve.
203 enum MalformedGenerics {
204 /// This link has unbalanced angle brackets.
206 /// For example, `Vec<T` should trigger this, as should `Vec<T>>`.
207 UnbalancedAngleBrackets,
208 /// The generics are not attached to a type.
210 /// For example, `<T>` should trigger this.
212 /// This is detected by checking if the path is empty after the generics are stripped.
214 /// The link uses fully-qualified syntax, which is currently unsupported.
216 /// For example, `<Vec as IntoIterator>::into_iter` should trigger this.
218 /// This is detected by checking if ` as ` (the keyword `as` with spaces around it) is inside
220 HasFullyQualifiedSyntax,
221 /// The link has an invalid path separator.
223 /// For example, `Vec:<T>:new()` should trigger this. Note that `Vec:new()` will **not**
224 /// trigger this because it has no generics and thus [`strip_generics_from_path`] will not be
227 /// Note that this will also **not** be triggered if the invalid path separator is inside angle
228 /// brackets because rustdoc mostly ignores what's inside angle brackets (except for
229 /// [`HasFullyQualifiedSyntax`](MalformedGenerics::HasFullyQualifiedSyntax)).
231 /// This is detected by checking if there is a colon followed by a non-colon in the link.
232 InvalidPathSeparator,
233 /// The link has too many angle brackets.
235 /// For example, `Vec<<T>>` should trigger this.
236 TooManyAngleBrackets,
237 /// The link has empty angle brackets.
239 /// For example, `Vec<>` should trigger this.
243 impl ResolutionFailure<'_> {
244 /// This resolved fully (not just partially) but is erroneous for some other reason
246 /// Returns the full resolution of the link, if present.
247 fn full_res(&self) -> Option<Res> {
249 Self::WrongNamespace { res, expected_ns: _ } => Some(*res),
256 /// User error: `[std#x#y]` is not valid
258 /// The anchor provided by the user conflicts with Rustdoc's generated anchor.
260 /// This is an unfortunate state of affairs. Not every item that can be
261 /// linked to has its own page; sometimes it is a subheading within a page,
262 /// like for associated items. In those cases, rustdoc uses an anchor to
263 /// link to the subheading. Since you can't have two anchors for the same
264 /// link, Rustdoc disallows having a user-specified anchor.
266 /// Most of the time this is fine, because you can just link to the page of
267 /// the item if you want to provide your own anchor.
268 RustdocAnchorConflict(Res),
271 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
272 crate enum UrlFragment {
278 /// Render the fragment, including the leading `#`.
279 crate fn render(&self, s: &mut String, tcx: TyCtxt<'_>) -> std::fmt::Result {
281 UrlFragment::Item(frag) => frag.render(s, tcx),
282 UrlFragment::UserWritten(raw) => write!(s, "#{}", raw),
287 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
288 crate struct ItemFragment(FragmentKind, DefId);
290 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
291 crate enum FragmentKind {
303 /// Create a fragment for an associated item.
304 #[instrument(level = "debug")]
305 fn from_assoc_item(item: &ty::AssocItem) -> Self {
306 let def_id = item.def_id;
308 ty::AssocKind::Fn => {
309 if item.defaultness.has_value() {
310 ItemFragment(FragmentKind::Method, def_id)
312 ItemFragment(FragmentKind::TyMethod, def_id)
315 ty::AssocKind::Const => ItemFragment(FragmentKind::AssociatedConstant, def_id),
316 ty::AssocKind::Type => ItemFragment(FragmentKind::AssociatedType, def_id),
320 /// Render the fragment, including the leading `#`.
321 crate fn render(&self, s: &mut String, tcx: TyCtxt<'_>) -> std::fmt::Result {
324 ItemFragment(kind, def_id) => {
325 let name = tcx.item_name(def_id);
327 FragmentKind::Method => write!(s, "method.{}", name),
328 FragmentKind::TyMethod => write!(s, "tymethod.{}", name),
329 FragmentKind::AssociatedConstant => write!(s, "associatedconstant.{}", name),
330 FragmentKind::AssociatedType => write!(s, "associatedtype.{}", name),
331 FragmentKind::StructField => write!(s, "structfield.{}", name),
332 FragmentKind::Variant => write!(s, "variant.{}", name),
333 FragmentKind::VariantField => {
334 let variant = tcx.item_name(tcx.parent(def_id).unwrap());
335 write!(s, "variant.{}.field.{}", variant, name)
343 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
344 struct ResolutionInfo {
347 dis: Option<Disambiguator>,
349 extra_fragment: Option<String>,
353 struct DiagnosticInfo<'a> {
357 link_range: Range<usize>,
360 #[derive(Clone, Debug, Hash)]
362 res: (Res, Option<UrlFragment>),
365 struct LinkCollector<'a, 'tcx> {
366 cx: &'a mut DocContext<'tcx>,
367 /// A stack of modules used to decide what scope to resolve in.
369 /// The last module will be used if the parent scope of the current item is
372 /// Cache the resolved links so we can avoid resolving (and emitting errors for) the same link.
373 /// The link will be `None` if it could not be resolved (i.e. the error was cached).
374 visited_links: FxHashMap<ResolutionInfo, Option<CachedLink>>,
377 impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
378 /// Given a full link, parse it as an [enum struct variant].
380 /// In particular, this will return an error whenever there aren't three
381 /// full path segments left in the link.
383 /// [enum struct variant]: rustc_hir::VariantData::Struct
384 fn variant_field<'path>(
386 path_str: &'path str,
389 ) -> Result<(Res, Option<ItemFragment>), ErrorKind<'path>> {
390 let tcx = self.cx.tcx;
391 let no_res = || ResolutionFailure::NotResolved {
395 unresolved: path_str.into(),
398 debug!("looking for enum variant {}", path_str);
399 let mut split = path_str.rsplitn(3, "::");
400 let variant_field_name = split
402 .map(|f| Symbol::intern(f))
403 .expect("fold_item should ensure link is non-empty");
405 // we're not sure this is a variant at all, so use the full string
406 // If there's no second component, the link looks like `[path]`.
407 // So there's no partial res and we should say the whole link failed to resolve.
408 split.next().map(|f| Symbol::intern(f)).ok_or_else(no_res)?;
411 .map(|f| f.to_owned())
412 // If there's no third component, we saw `[a::b]` before and it failed to resolve.
413 // So there's no partial res.
414 .ok_or_else(no_res)?;
415 let ty_res = self.resolve_path(&path, TypeNS, item_id, module_id).ok_or_else(no_res)?;
418 Res::Def(DefKind::Enum, did) => {
422 .flat_map(|imp| tcx.associated_items(*imp).in_definition_order())
423 .any(|item| item.name == variant_name)
425 // This is just to let `fold_item` know that this shouldn't be considered;
426 // it's a bug for the error to make it to the user
427 return Err(ResolutionFailure::Dummy.into());
429 match tcx.type_of(did).kind() {
430 ty::Adt(def, _) if def.is_enum() => {
431 if let Some(field) = def.all_fields().find(|f| f.name == variant_field_name)
433 Ok((ty_res, Some(ItemFragment(FragmentKind::VariantField, field.did))))
435 Err(ResolutionFailure::NotResolved {
438 partial_res: Some(Res::Def(DefKind::Enum, def.did())),
439 unresolved: variant_field_name.to_string().into(),
447 _ => Err(ResolutionFailure::NotResolved {
450 partial_res: Some(ty_res),
451 unresolved: variant_name.to_string().into(),
457 /// Given a primitive type, try to resolve an associated item.
458 fn resolve_primitive_associated_item(
460 prim_ty: PrimitiveType,
463 ) -> Option<(Res, ItemFragment)> {
464 let tcx = self.cx.tcx;
466 prim_ty.impls(tcx).find_map(|impl_| {
467 tcx.associated_items(impl_)
468 .find_by_name_and_namespace(tcx, Ident::with_dummy_span(item_name), ns, impl_)
470 let fragment = ItemFragment::from_assoc_item(item);
471 (Res::Primitive(prim_ty), fragment)
476 /// Resolves a string as a macro.
478 /// FIXME(jynelson): Can this be unified with `resolve()`?
484 ) -> Result<Res, ResolutionFailure<'a>> {
485 self.resolve_path(path_str, MacroNS, item_id, module_id).ok_or_else(|| {
486 ResolutionFailure::NotResolved {
490 unresolved: path_str.into(),
495 fn resolve_self_ty(&self, path_str: &str, ns: Namespace, item_id: ItemId) -> Option<Res> {
496 if ns != TypeNS || path_str != "Self" {
500 let tcx = self.cx.tcx;
503 .map(|def_id| match tcx.def_kind(def_id) {
504 def_kind @ (DefKind::AssocFn
505 | DefKind::AssocConst
508 | DefKind::Field) => {
509 let parent_def_id = tcx.parent(def_id).expect("nested item has no parent");
510 if def_kind == DefKind::Field && tcx.def_kind(parent_def_id) == DefKind::Variant
512 tcx.parent(parent_def_id).expect("variant has no parent")
519 .and_then(|self_id| match tcx.def_kind(self_id) {
520 DefKind::Impl => self.def_id_to_res(self_id),
521 def_kind => Some(Res::Def(def_kind, self_id)),
525 /// HACK: Try to search the macro name in the list of all `macro_rules` items in the crate.
526 /// Used when nothing else works, may often give an incorrect result.
527 fn resolve_macro_rules(&self, path_str: &str, ns: Namespace) -> Option<Res> {
535 .get(&Symbol::intern(path_str))
537 .and_then(|res| res.try_into().ok())
540 /// Convenience wrapper around `resolve_rustdoc_path`.
542 /// This also handles resolving `true` and `false` as booleans.
543 /// NOTE: `resolve_rustdoc_path` knows only about paths, not about types.
544 /// Associated items will never be resolved by this function.
552 if let res @ Some(..) = self.resolve_self_ty(path_str, ns, item_id) {
556 // Resolver doesn't know about true, false, and types that aren't paths (e.g. `()`).
559 .enter_resolver(|resolver| resolver.resolve_rustdoc_path(path_str, ns, module_id))
560 .and_then(|res| res.try_into().ok())
561 .or_else(|| resolve_primitive(path_str, ns))
562 .or_else(|| self.resolve_macro_rules(path_str, ns));
563 debug!("{} resolved to {:?} in namespace {:?}", path_str, result, ns);
567 /// Resolves a string as a path within a particular namespace. Returns an
568 /// optional URL fragment in the case of variants and methods.
571 path_str: &'path str,
575 user_fragment: &Option<String>,
576 ) -> Result<(Res, Option<UrlFragment>), ErrorKind<'path>> {
577 let (res, rustdoc_fragment) = self.resolve_inner(path_str, ns, item_id, module_id)?;
578 let chosen_fragment = match (user_fragment, rustdoc_fragment) {
579 (Some(_), Some(r_frag)) => {
580 let diag_res = match r_frag {
581 ItemFragment(_, did) => Res::Def(self.cx.tcx.def_kind(did), did),
583 let failure = AnchorFailure::RustdocAnchorConflict(diag_res);
584 return Err(ErrorKind::AnchorFailure(failure));
586 (Some(u_frag), None) => Some(UrlFragment::UserWritten(u_frag.clone())),
587 (None, Some(r_frag)) => Some(UrlFragment::Item(r_frag)),
588 (None, None) => None,
590 Ok((res, chosen_fragment))
593 fn resolve_inner<'path>(
595 path_str: &'path str,
599 ) -> Result<(Res, Option<ItemFragment>), ErrorKind<'path>> {
600 if let Some(res) = self.resolve_path(path_str, ns, item_id, module_id) {
602 // FIXME(#76467): make this fallthrough to lookup the associated
603 // item a separate function.
604 Res::Def(DefKind::AssocFn | DefKind::AssocConst, _) => assert_eq!(ns, ValueNS),
605 Res::Def(DefKind::AssocTy, _) => assert_eq!(ns, TypeNS),
606 Res::Def(DefKind::Variant, _) => {
607 return handle_variant(self.cx, res);
609 // Not a trait item; just return what we found.
610 _ => return Ok((res, None)),
614 // Try looking for methods and associated items.
615 let mut split = path_str.rsplitn(2, "::");
616 // NB: `split`'s first element is always defined, even if the delimiter was not present.
617 // NB: `item_str` could be empty when resolving in the root namespace (e.g. `::std`).
618 let item_str = split.next().unwrap();
619 let item_name = Symbol::intern(item_str);
620 let path_root = split
622 .map(|f| f.to_owned())
623 // If there's no `::`, it's not an associated item.
624 // So we can be sure that `rustc_resolve` was accurate when it said it wasn't resolved.
626 debug!("found no `::`, assumming {} was correctly not in scope", item_name);
627 ResolutionFailure::NotResolved {
631 unresolved: item_str.into(),
635 // FIXME(#83862): this arbitrarily gives precedence to primitives over modules to support
636 // links to primitives when `#[doc(primitive)]` is present. It should give an ambiguity
637 // error instead and special case *only* modules with `#[doc(primitive)]`, not all
639 resolve_primitive(&path_root, TypeNS)
640 .or_else(|| self.resolve_path(&path_root, TypeNS, item_id, module_id))
642 let (res, fragment) =
643 self.resolve_associated_item(ty_res, item_name, ns, module_id)?;
645 Some(Ok((res, Some(fragment))))
648 if ns == Namespace::ValueNS {
649 self.variant_field(path_str, item_id, module_id)
651 Err(ResolutionFailure::NotResolved {
655 unresolved: path_root.into(),
662 /// Convert a DefId to a Res, where possible.
664 /// This is used for resolving type aliases.
665 fn def_id_to_res(&self, ty_id: DefId) -> Option<Res> {
666 use PrimitiveType::*;
667 Some(match *self.cx.tcx.type_of(ty_id).kind() {
668 ty::Bool => Res::Primitive(Bool),
669 ty::Char => Res::Primitive(Char),
670 ty::Int(ity) => Res::Primitive(ity.into()),
671 ty::Uint(uty) => Res::Primitive(uty.into()),
672 ty::Float(fty) => Res::Primitive(fty.into()),
673 ty::Str => Res::Primitive(Str),
674 ty::Tuple(tys) if tys.is_empty() => Res::Primitive(Unit),
675 ty::Tuple(_) => Res::Primitive(Tuple),
676 ty::Array(..) => Res::Primitive(Array),
677 ty::Slice(_) => Res::Primitive(Slice),
678 ty::RawPtr(_) => Res::Primitive(RawPointer),
679 ty::Ref(..) => Res::Primitive(Reference),
680 ty::FnDef(..) => panic!("type alias to a function definition"),
681 ty::FnPtr(_) => Res::Primitive(Fn),
682 ty::Never => Res::Primitive(Never),
683 ty::Adt(ty::AdtDef(Interned(&ty::AdtDefData { did, .. }, _)), _) | ty::Foreign(did) => {
684 Res::Def(self.cx.tcx.def_kind(did), did)
689 | ty::GeneratorWitness(_)
696 | ty::Error(_) => return None,
700 /// Convert a PrimitiveType to a Ty, where possible.
702 /// This is used for resolving trait impls for primitives
703 fn primitive_type_to_ty(&mut self, prim: PrimitiveType) -> Option<Ty<'tcx>> {
704 use PrimitiveType::*;
705 let tcx = self.cx.tcx;
707 // FIXME: Only simple types are supported here, see if we can support
708 // other types such as Tuple, Array, Slice, etc.
709 // See https://github.com/rust-lang/rust/issues/90703#issuecomment-1004263455
710 Some(tcx.mk_ty(match prim {
715 I8 => ty::Int(ty::IntTy::I8),
716 I16 => ty::Int(ty::IntTy::I16),
717 I32 => ty::Int(ty::IntTy::I32),
718 I64 => ty::Int(ty::IntTy::I64),
719 I128 => ty::Int(ty::IntTy::I128),
720 Isize => ty::Int(ty::IntTy::Isize),
721 F32 => ty::Float(ty::FloatTy::F32),
722 F64 => ty::Float(ty::FloatTy::F64),
723 U8 => ty::Uint(ty::UintTy::U8),
724 U16 => ty::Uint(ty::UintTy::U16),
725 U32 => ty::Uint(ty::UintTy::U32),
726 U64 => ty::Uint(ty::UintTy::U64),
727 U128 => ty::Uint(ty::UintTy::U128),
728 Usize => ty::Uint(ty::UintTy::Usize),
733 /// Resolve an associated item, returning its containing page's `Res`
734 /// and the fragment targeting the associated item on its page.
735 fn resolve_associated_item(
741 ) -> Option<(Res, ItemFragment)> {
742 let tcx = self.cx.tcx;
745 Res::Primitive(prim) => {
746 self.resolve_primitive_associated_item(prim, ns, item_name).or_else(|| {
747 let assoc_item = self
748 .primitive_type_to_ty(prim)
750 resolve_associated_trait_item(ty, module_id, item_name, ns, self.cx)
754 assoc_item.map(|item| {
755 let fragment = ItemFragment::from_assoc_item(&item);
760 Res::Def(DefKind::TyAlias, did) => {
761 // Resolve the link on the type the alias points to.
762 // FIXME: if the associated item is defined directly on the type alias,
763 // it will show up on its documentation page, we should link there instead.
764 let res = self.def_id_to_res(did)?;
765 self.resolve_associated_item(res, item_name, ns, module_id)
768 def_kind @ (DefKind::Struct | DefKind::Union | DefKind::Enum | DefKind::ForeignTy),
771 debug!("looking for associated item named {} for item {:?}", item_name, did);
772 // Checks if item_name is a variant of the `SomeItem` enum
773 if ns == TypeNS && def_kind == DefKind::Enum {
774 match tcx.type_of(did).kind() {
775 ty::Adt(adt_def, _) => {
776 for variant in adt_def.variants() {
777 if variant.name == item_name {
780 ItemFragment(FragmentKind::Variant, variant.def_id),
789 // Checks if item_name belongs to `impl SomeItem`
794 tcx.associated_items(imp).find_by_name_and_namespace(
796 Ident::with_dummy_span(item_name),
802 // There should only ever be one associated item that matches from any inherent impl
804 // Check if item_name belongs to `impl SomeTrait for SomeItem`
805 // FIXME(#74563): This gives precedence to `impl SomeItem`:
806 // Although having both would be ambiguous, use impl version for compatibility's sake.
807 // To handle that properly resolve() would have to support
808 // something like [`ambi_fn`](<SomeStruct as SomeTrait>::ambi_fn)
810 resolve_associated_trait_item(
819 debug!("got associated item {:?}", assoc_item);
821 if let Some(item) = assoc_item {
822 let fragment = ItemFragment::from_assoc_item(&item);
823 return Some((root_res, fragment));
826 if ns != Namespace::ValueNS {
829 debug!("looking for fields named {} for {:?}", item_name, did);
830 // FIXME: this doesn't really belong in `associated_item` (maybe `variant_field` is better?)
831 // NOTE: it's different from variant_field because it only resolves struct fields,
832 // not variant fields (2 path segments, not 3).
834 // We need to handle struct (and union) fields in this code because
835 // syntactically their paths are identical to associated item paths:
836 // `module::Type::field` and `module::Type::Assoc`.
838 // On the other hand, variant fields can't be mistaken for associated
839 // items because they look like this: `module::Type::Variant::field`.
841 // Variants themselves don't need to be handled here, even though
842 // they also look like associated items (`module::Type::Variant`),
843 // because they are real Rust syntax (unlike the intra-doc links
844 // field syntax) and are handled by the compiler's resolver.
845 let def = match tcx.type_of(did).kind() {
846 ty::Adt(def, _) if !def.is_enum() => def,
850 def.non_enum_variant().fields.iter().find(|item| item.name == item_name)?;
851 Some((root_res, ItemFragment(FragmentKind::StructField, field.did)))
853 Res::Def(DefKind::Trait, did) => tcx
854 .associated_items(did)
855 .find_by_name_and_namespace(tcx, Ident::with_dummy_span(item_name), ns, did)
857 let fragment = ItemFragment::from_assoc_item(item);
858 let res = Res::Def(item.kind.as_def_kind(), item.def_id);
865 /// Used for reporting better errors.
867 /// Returns whether the link resolved 'fully' in another namespace.
868 /// 'fully' here means that all parts of the link resolved, not just some path segments.
869 /// This returns the `Res` even if it was erroneous for some reason
870 /// (such as having invalid URL fragments or being in the wrong namespace).
877 extra_fragment: &Option<String>,
879 // resolve() can't be used for macro namespace
880 let result = match ns {
881 Namespace::MacroNS => self
882 .resolve_macro(path_str, item_id, module_id)
883 .map(|res| (res, None))
884 .map_err(ErrorKind::from),
885 Namespace::TypeNS | Namespace::ValueNS => {
886 self.resolve(path_str, ns, item_id, module_id, extra_fragment)
890 let res = match result {
892 if let Some(UrlFragment::Item(ItemFragment(_, id))) = frag {
893 Some(Res::Def(self.cx.tcx.def_kind(id), id))
898 Err(ErrorKind::Resolve(box kind)) => kind.full_res(),
899 Err(ErrorKind::AnchorFailure(AnchorFailure::RustdocAnchorConflict(res))) => Some(res),
900 Err(ErrorKind::AnchorFailure(AnchorFailure::MultipleAnchors)) => None,
906 /// Look to see if a resolved item has an associated item named `item_name`.
908 /// Given `[std::io::Error::source]`, where `source` is unresolved, this would
909 /// find `std::error::Error::source` and return
910 /// `<io::Error as error::Error>::source`.
911 fn resolve_associated_trait_item<'a>(
916 cx: &mut DocContext<'a>,
917 ) -> Option<ty::AssocItem> {
918 // FIXME: this should also consider blanket impls (`impl<T> X for T`). Unfortunately
919 // `get_auto_trait_and_blanket_impls` is broken because the caching behavior is wrong. In the
920 // meantime, just don't look for these blanket impls.
922 // Next consider explicit impls: `impl MyTrait for MyType`
923 // Give precedence to inherent impls.
924 let traits = trait_impls_for(cx, ty, module);
925 debug!("considering traits {:?}", traits);
926 let mut candidates = traits.iter().filter_map(|&(impl_, trait_)| {
928 .associated_items(trait_)
929 .find_by_name_and_namespace(cx.tcx, Ident::with_dummy_span(item_name), ns, trait_)
931 trait_assoc_to_impl_assoc_item(cx.tcx, impl_, trait_assoc.def_id)
932 .unwrap_or(trait_assoc)
935 // FIXME(#74563): warn about ambiguity
936 debug!("the candidates were {:?}", candidates.clone().collect::<Vec<_>>());
937 candidates.next().copied()
940 /// Find the associated item in the impl `impl_id` that corresponds to the
941 /// trait associated item `trait_assoc_id`.
943 /// This function returns `None` if no associated item was found in the impl.
944 /// This can occur when the trait associated item has a default value that is
945 /// not overridden in the impl.
947 /// This is just a wrapper around [`TyCtxt::impl_item_implementor_ids()`] and
948 /// [`TyCtxt::associated_item()`] (with some helpful logging added).
949 #[instrument(level = "debug", skip(tcx))]
950 fn trait_assoc_to_impl_assoc_item<'tcx>(
953 trait_assoc_id: DefId,
954 ) -> Option<&'tcx ty::AssocItem> {
955 let trait_to_impl_assoc_map = tcx.impl_item_implementor_ids(impl_id);
956 debug!(?trait_to_impl_assoc_map);
957 let impl_assoc_id = *trait_to_impl_assoc_map.get(&trait_assoc_id)?;
958 debug!(?impl_assoc_id);
959 let impl_assoc = tcx.associated_item(impl_assoc_id);
964 /// Given a type, return all trait impls in scope in `module` for that type.
965 /// Returns a set of pairs of `(impl_id, trait_id)`.
967 /// NOTE: this cannot be a query because more traits could be available when more crates are compiled!
968 /// So it is not stable to serialize cross-crate.
969 #[instrument(level = "debug", skip(cx))]
970 fn trait_impls_for<'a>(
971 cx: &mut DocContext<'a>,
974 ) -> FxHashSet<(DefId, DefId)> {
976 let iter = cx.resolver_caches.traits_in_scope[&module].iter().flat_map(|trait_candidate| {
977 let trait_ = trait_candidate.def_id;
978 trace!("considering explicit impl for trait {:?}", trait_);
980 // Look at each trait implementation to see if it's an impl for `did`
981 tcx.find_map_relevant_impl(trait_, ty, |impl_| {
982 let trait_ref = tcx.impl_trait_ref(impl_).expect("this is not an inherent impl");
983 // Check if these are the same type.
984 let impl_type = trait_ref.self_ty();
986 "comparing type {} with kind {:?} against type {:?}",
991 // Fast path: if this is a primitive simple `==` will work
992 // NOTE: the `match` is necessary; see #92662.
993 // this allows us to ignore generics because the user input
994 // may not include the generic placeholders
995 // e.g. this allows us to match Foo (user comment) with Foo<T> (actual type)
996 let saw_impl = impl_type == ty
997 || match (impl_type.kind(), ty.kind()) {
998 (ty::Adt(impl_def, _), ty::Adt(ty_def, _)) => {
999 debug!("impl def_id: {:?}, ty def_id: {:?}", impl_def.did(), ty_def.did());
1000 impl_def.did() == ty_def.did()
1005 if saw_impl { Some((impl_, trait_)) } else { None }
1011 /// Check for resolve collisions between a trait and its derive.
1013 /// These are common and we should just resolve to the trait in that case.
1014 fn is_derive_trait_collision<T>(ns: &PerNS<Result<(Res, T), ResolutionFailure<'_>>>) -> bool {
1018 type_ns: Ok((Res::Def(DefKind::Trait, _), _)),
1019 macro_ns: Ok((Res::Def(DefKind::Macro(MacroKind::Derive), _), _)),
1025 impl<'a, 'tcx> DocVisitor for LinkCollector<'a, 'tcx> {
1026 fn visit_item(&mut self, item: &Item) {
1028 item.def_id.as_def_id().and_then(|did| find_nearest_parent_module(self.cx.tcx, did));
1029 if parent_node.is_some() {
1030 trace!("got parent node for {:?} {:?}, id {:?}", item.type_(), item.name, item.def_id);
1033 let inner_docs = item.inner_docs(self.cx.tcx);
1035 if item.is_mod() && inner_docs {
1036 self.mod_ids.push(item.def_id.expect_def_id());
1039 // We want to resolve in the lexical scope of the documentation.
1040 // In the presence of re-exports, this is not the same as the module of the item.
1041 // Rather than merging all documentation into one, resolve it one attribute at a time
1042 // so we know which module it came from.
1043 for (parent_module, doc) in item.attrs.collapsed_doc_value_by_module_level() {
1044 debug!("combined_docs={}", doc);
1045 // NOTE: if there are links that start in one crate and end in another, this will not resolve them.
1046 // This is a degenerate case and it's not supported by rustdoc.
1047 let parent_node = parent_module.or(parent_node);
1048 for md_link in markdown_links(&doc) {
1049 let link = self.resolve_link(&item, &doc, parent_node, md_link);
1050 if let Some(link) = link {
1051 self.cx.cache.intra_doc_links.entry(item.def_id).or_default().push(link);
1058 self.mod_ids.push(item.def_id.expect_def_id());
1061 self.visit_item_recur(item);
1064 self.visit_item_recur(item)
1069 enum PreprocessingError<'a> {
1070 Anchor(AnchorFailure),
1071 Disambiguator(Range<usize>, String),
1072 Resolution(ResolutionFailure<'a>, String, Option<Disambiguator>),
1075 impl From<AnchorFailure> for PreprocessingError<'_> {
1076 fn from(err: AnchorFailure) -> Self {
1081 struct PreprocessingInfo {
1083 disambiguator: Option<Disambiguator>,
1084 extra_fragment: Option<String>,
1089 /// - `None` if the link should be ignored.
1090 /// - `Some(Err)` if the link should emit an error
1091 /// - `Some(Ok)` if the link is valid
1093 /// `link_buffer` is needed for lifetime reasons; it will always be overwritten and the contents ignored.
1094 fn preprocess_link<'a>(
1095 ori_link: &'a MarkdownLink,
1096 ) -> Option<Result<PreprocessingInfo, PreprocessingError<'a>>> {
1097 // [] is mostly likely not supposed to be a link
1098 if ori_link.link.is_empty() {
1102 // Bail early for real links.
1103 if ori_link.link.contains('/') {
1107 let stripped = ori_link.link.replace('`', "");
1108 let mut parts = stripped.split('#');
1110 let link = parts.next().unwrap();
1111 if link.trim().is_empty() {
1112 // This is an anchor to an element of the current page, nothing to do in here!
1115 let extra_fragment = parts.next();
1116 if parts.next().is_some() {
1117 // A valid link can't have multiple #'s
1118 return Some(Err(AnchorFailure::MultipleAnchors.into()));
1121 // Parse and strip the disambiguator from the link, if present.
1122 let (disambiguator, path_str, link_text) = match Disambiguator::from_str(link) {
1123 Ok(Some((d, path, link_text))) => (Some(d), path.trim(), link_text.trim()),
1124 Ok(None) => (None, link.trim(), link.trim()),
1125 Err((err_msg, relative_range)) => {
1126 // Only report error if we would not have ignored this link. See issue #83859.
1127 if !should_ignore_link_with_disambiguators(link) {
1128 let no_backticks_range = range_between_backticks(ori_link);
1129 let disambiguator_range = (no_backticks_range.start + relative_range.start)
1130 ..(no_backticks_range.start + relative_range.end);
1131 return Some(Err(PreprocessingError::Disambiguator(disambiguator_range, err_msg)));
1138 if should_ignore_link(path_str) {
1142 // Strip generics from the path.
1143 let path_str = if path_str.contains(['<', '>'].as_slice()) {
1144 match strip_generics_from_path(path_str) {
1147 debug!("link has malformed generics: {}", path_str);
1148 return Some(Err(PreprocessingError::Resolution(
1150 path_str.to_owned(),
1159 // Sanity check to make sure we don't have any angle brackets after stripping generics.
1160 assert!(!path_str.contains(['<', '>'].as_slice()));
1162 // The link is not an intra-doc link if it still contains spaces after stripping generics.
1163 if path_str.contains(' ') {
1167 Some(Ok(PreprocessingInfo {
1170 extra_fragment: extra_fragment.map(|frag| frag.to_owned()),
1171 link_text: link_text.to_owned(),
1175 impl LinkCollector<'_, '_> {
1176 /// This is the entry point for resolving an intra-doc link.
1178 /// FIXME(jynelson): this is way too many arguments
1183 parent_node: Option<DefId>,
1184 ori_link: MarkdownLink,
1185 ) -> Option<ItemLink> {
1186 trace!("considering link '{}'", ori_link.link);
1188 let diag_info = DiagnosticInfo {
1191 ori_link: &ori_link.link,
1192 link_range: ori_link.range.clone(),
1195 let PreprocessingInfo { ref path_str, disambiguator, extra_fragment, link_text } =
1196 match preprocess_link(&ori_link)? {
1200 PreprocessingError::Anchor(err) => anchor_failure(self.cx, diag_info, err),
1201 PreprocessingError::Disambiguator(range, msg) => {
1202 disambiguator_error(self.cx, diag_info, range, &msg)
1204 PreprocessingError::Resolution(err, path_str, disambiguator) => {
1218 let inner_docs = item.inner_docs(self.cx.tcx);
1220 // In order to correctly resolve intra-doc links we need to
1221 // pick a base AST node to work from. If the documentation for
1222 // this module came from an inner comment (//!) then we anchor
1223 // our name resolution *inside* the module. If, on the other
1224 // hand it was an outer comment (///) then we anchor the name
1225 // resolution in the parent module on the basis that the names
1226 // used are more likely to be intended to be parent names. For
1227 // this, we set base_node to None for inner comments since
1228 // we've already pushed this node onto the resolution stack but
1229 // for outer comments we explicitly try and resolve against the
1230 // parent_node first.
1232 if item.is_mod() && inner_docs { self.mod_ids.last().copied() } else { parent_node };
1234 let Some(module_id) = base_node else {
1236 debug!("attempting to resolve item without parent module: {}", path_str);
1242 smallvec![ResolutionFailure::NoParentItem],
1247 let (mut res, fragment) = self.resolve_with_disambiguator_cached(
1249 item_id: item.def_id,
1252 path_str: path_str.to_owned(),
1255 diag_info.clone(), // this struct should really be Copy, but Range is not :(
1256 matches!(ori_link.kind, LinkType::Reference | LinkType::Shortcut),
1259 // Check for a primitive which might conflict with a module
1260 // Report the ambiguity and require that the user specify which one they meant.
1261 // FIXME: could there ever be a primitive not in the type namespace?
1264 None | Some(Disambiguator::Namespace(Namespace::TypeNS) | Disambiguator::Primitive)
1265 ) && !matches!(res, Res::Primitive(_))
1267 if let Some(prim) = resolve_primitive(path_str, TypeNS) {
1269 if matches!(disambiguator, Some(Disambiguator::Primitive)) {
1272 // `[char]` when a `char` module is in scope
1273 let candidates = vec![res, prim];
1274 ambiguity_error(self.cx, diag_info, path_str, candidates);
1281 Res::Primitive(prim) => {
1282 if let Some(UrlFragment::Item(ItemFragment(_, id))) = fragment {
1283 // We're actually resolving an associated item of a primitive, so we need to
1284 // verify the disambiguator (if any) matches the type of the associated item.
1285 // This case should really follow the same flow as the `Res::Def` branch below,
1286 // but attempting to add a call to `clean::register_res` causes an ICE. @jyn514
1287 // thinks `register_res` is only needed for cross-crate re-exports, but Rust
1288 // doesn't allow statements like `use str::trim;`, making this a (hopefully)
1289 // valid omission. See https://github.com/rust-lang/rust/pull/80660#discussion_r551585677
1290 // for discussion on the matter.
1291 let kind = self.cx.tcx.def_kind(id);
1292 self.verify_disambiguator(
1302 // FIXME: it would be nice to check that the feature gate was enabled in the original crate, not just ignore it altogether.
1303 // However I'm not sure how to check that across crates.
1304 if prim == PrimitiveType::RawPointer
1305 && item.def_id.is_local()
1306 && !self.cx.tcx.features().intra_doc_pointers
1308 self.report_rawptr_assoc_feature_gate(dox, &ori_link, item);
1311 match disambiguator {
1312 Some(Disambiguator::Primitive | Disambiguator::Namespace(_)) | None => {}
1314 self.report_disambiguator_mismatch(
1315 path_str, &ori_link, other, res, &diag_info,
1323 link: ori_link.link,
1325 did: res.def_id(self.cx.tcx),
1329 Res::Def(kind, id) => {
1330 let (kind_for_dis, id_for_dis) =
1331 if let Some(UrlFragment::Item(ItemFragment(_, id))) = fragment {
1332 (self.cx.tcx.def_kind(id), id)
1336 self.verify_disambiguator(
1345 let id = clean::register_res(self.cx, rustc_hir::def::Res::Def(kind, id));
1346 Some(ItemLink { link: ori_link.link, link_text, did: id, fragment })
1351 fn verify_disambiguator(
1354 ori_link: &MarkdownLink,
1357 disambiguator: Option<Disambiguator>,
1359 diag_info: &DiagnosticInfo<'_>,
1361 debug!("intra-doc link to {} resolved to {:?}", path_str, (kind, id));
1363 // Disallow e.g. linking to enums with `struct@`
1364 debug!("saw kind {:?} with disambiguator {:?}", kind, disambiguator);
1365 match (kind, disambiguator) {
1366 | (DefKind::Const | DefKind::ConstParam | DefKind::AssocConst | DefKind::AnonConst, Some(Disambiguator::Kind(DefKind::Const)))
1367 // NOTE: this allows 'method' to mean both normal functions and associated functions
1368 // This can't cause ambiguity because both are in the same namespace.
1369 | (DefKind::Fn | DefKind::AssocFn, Some(Disambiguator::Kind(DefKind::Fn)))
1370 // These are namespaces; allow anything in the namespace to match
1371 | (_, Some(Disambiguator::Namespace(_)))
1372 // If no disambiguator given, allow anything
1374 // All of these are valid, so do nothing
1376 (actual, Some(Disambiguator::Kind(expected))) if actual == expected => {}
1377 (_, Some(specified @ Disambiguator::Kind(_) | specified @ Disambiguator::Primitive)) => {
1378 self.report_disambiguator_mismatch(path_str,ori_link,specified, Res::Def(kind, id),diag_info);
1383 // item can be non-local e.g. when using #[doc(primitive = "pointer")]
1384 if let Some((src_id, dst_id)) = id
1386 // The `expect_def_id()` should be okay because `local_def_id_to_hir_id`
1387 // would presumably panic if a fake `DefIndex` were passed.
1388 .and_then(|dst_id| {
1389 item.def_id.expect_def_id().as_local().map(|src_id| (src_id, dst_id))
1392 if self.cx.tcx.privacy_access_levels(()).is_exported(src_id)
1393 && !self.cx.tcx.privacy_access_levels(()).is_exported(dst_id)
1395 privacy_error(self.cx, diag_info, path_str);
1402 fn report_disambiguator_mismatch(
1405 ori_link: &MarkdownLink,
1406 specified: Disambiguator,
1408 diag_info: &DiagnosticInfo<'_>,
1410 // The resolved item did not match the disambiguator; give a better error than 'not found'
1411 let msg = format!("incompatible link kind for `{}`", path_str);
1412 let callback = |diag: &mut Diagnostic, sp: Option<rustc_span::Span>| {
1414 "this link resolved to {} {}, which is not {} {}",
1417 specified.article(),
1420 if let Some(sp) = sp {
1421 diag.span_label(sp, ¬e);
1425 suggest_disambiguator(resolved, diag, path_str, &ori_link.link, sp);
1427 report_diagnostic(self.cx.tcx, BROKEN_INTRA_DOC_LINKS, &msg, &diag_info, callback);
1430 fn report_rawptr_assoc_feature_gate(&self, dox: &str, ori_link: &MarkdownLink, item: &Item) {
1432 super::source_span_for_markdown_range(self.cx.tcx, dox, &ori_link.range, &item.attrs)
1433 .unwrap_or_else(|| item.attr_span(self.cx.tcx));
1434 rustc_session::parse::feature_err(
1435 &self.cx.tcx.sess.parse_sess,
1436 sym::intra_doc_pointers,
1438 "linking to associated items of raw pointers is experimental",
1440 .note("rustdoc does not allow disambiguating between `*const` and `*mut`, and pointers are unstable until it does")
1444 fn resolve_with_disambiguator_cached(
1446 key: ResolutionInfo,
1447 diag: DiagnosticInfo<'_>,
1448 cache_resolution_failure: bool,
1449 ) -> Option<(Res, Option<UrlFragment>)> {
1450 if let Some(ref cached) = self.visited_links.get(&key) {
1453 return Some(cached.res.clone());
1455 None if cache_resolution_failure => return None,
1457 // Although we hit the cache and found a resolution error, this link isn't
1458 // supposed to cache those. Run link resolution again to emit the expected
1459 // resolution error.
1464 let res = self.resolve_with_disambiguator(&key, diag);
1466 // Cache only if resolved successfully - don't silence duplicate errors
1467 if let Some(res) = res {
1468 // Store result for the actual namespace
1469 self.visited_links.insert(key, Some(CachedLink { res: res.clone() }));
1473 if cache_resolution_failure {
1474 // For reference-style links we only want to report one resolution error
1475 // so let's cache them as well.
1476 self.visited_links.insert(key, None);
1483 /// After parsing the disambiguator, resolve the main part of the link.
1484 // FIXME(jynelson): wow this is just so much
1485 fn resolve_with_disambiguator(
1487 key: &ResolutionInfo,
1488 diag: DiagnosticInfo<'_>,
1489 ) -> Option<(Res, Option<UrlFragment>)> {
1490 let disambiguator = key.dis;
1491 let path_str = &key.path_str;
1492 let item_id = key.item_id;
1493 let base_node = key.module_id;
1494 let extra_fragment = &key.extra_fragment;
1496 match disambiguator.map(Disambiguator::ns) {
1497 Some(expected_ns @ (ValueNS | TypeNS)) => {
1498 match self.resolve(path_str, expected_ns, item_id, base_node, extra_fragment) {
1499 Ok(res) => Some(res),
1500 Err(ErrorKind::Resolve(box mut kind)) => {
1501 // We only looked in one namespace. Try to give a better error if possible.
1502 if kind.full_res().is_none() {
1503 let other_ns = if expected_ns == ValueNS { TypeNS } else { ValueNS };
1504 // FIXME: really it should be `resolution_failure` that does this, not `resolve_with_disambiguator`
1505 // See https://github.com/rust-lang/rust/pull/76955#discussion_r493953382 for a good approach
1506 for new_ns in [other_ns, MacroNS] {
1507 if let Some(res) = self.check_full_res(
1514 kind = ResolutionFailure::WrongNamespace { res, expected_ns };
1519 resolution_failure(self, diag, path_str, disambiguator, smallvec![kind]);
1520 // This could just be a normal link or a broken link
1521 // we could potentially check if something is
1522 // "intra-doc-link-like" and warn in that case.
1525 Err(ErrorKind::AnchorFailure(msg)) => {
1526 anchor_failure(self.cx, diag, msg);
1533 let mut candidates = PerNS {
1535 .resolve_macro(path_str, item_id, base_node)
1536 .map(|res| (res, extra_fragment.clone().map(UrlFragment::UserWritten))),
1537 type_ns: match self.resolve(
1545 debug!("got res in TypeNS: {:?}", res);
1548 Err(ErrorKind::AnchorFailure(msg)) => {
1549 anchor_failure(self.cx, diag, msg);
1552 Err(ErrorKind::Resolve(box kind)) => Err(kind),
1554 value_ns: match self.resolve(
1562 Err(ErrorKind::AnchorFailure(msg)) => {
1563 anchor_failure(self.cx, diag, msg);
1566 Err(ErrorKind::Resolve(box kind)) => Err(kind),
1568 .and_then(|(res, fragment)| {
1569 // Constructors are picked up in the type namespace.
1571 Res::Def(DefKind::Ctor(..), _) => {
1572 Err(ResolutionFailure::WrongNamespace { res, expected_ns: TypeNS })
1575 match (fragment, extra_fragment.clone()) {
1576 (Some(fragment), Some(_)) => {
1577 // Shouldn't happen but who knows?
1578 Ok((res, Some(fragment)))
1580 (fragment, None) => Ok((res, fragment)),
1581 (None, fragment) => {
1582 Ok((res, fragment.map(UrlFragment::UserWritten)))
1590 let len = candidates.iter().filter(|res| res.is_ok()).count();
1598 candidates.into_iter().filter_map(|res| res.err()).collect(),
1600 // this could just be a normal link
1605 Some(candidates.into_iter().find_map(|res| res.ok()).unwrap())
1606 } else if len == 2 && is_derive_trait_collision(&candidates) {
1607 Some(candidates.type_ns.unwrap())
1609 if is_derive_trait_collision(&candidates) {
1610 candidates.macro_ns = Err(ResolutionFailure::Dummy);
1612 // If we're reporting an ambiguity, don't mention the namespaces that failed
1613 let candidates = candidates.map(|candidate| candidate.ok().map(|(res, _)| res));
1614 ambiguity_error(self.cx, diag, path_str, candidates.present_items().collect());
1619 match self.resolve_macro(path_str, item_id, base_node) {
1620 Ok(res) => Some((res, extra_fragment.clone().map(UrlFragment::UserWritten))),
1622 // `resolve_macro` only looks in the macro namespace. Try to give a better error if possible.
1623 for ns in [TypeNS, ValueNS] {
1624 if let Some(res) = self.check_full_res(
1632 ResolutionFailure::WrongNamespace { res, expected_ns: MacroNS };
1636 resolution_failure(self, diag, path_str, disambiguator, smallvec![kind]);
1645 /// Get the section of a link between the backticks,
1646 /// or the whole link if there aren't any backticks.
1654 fn range_between_backticks(ori_link: &MarkdownLink) -> Range<usize> {
1655 let after_first_backtick_group = ori_link.link.bytes().position(|b| b != b'`').unwrap_or(0);
1656 let before_second_backtick_group = ori_link
1659 .skip(after_first_backtick_group)
1660 .position(|b| b == b'`')
1661 .unwrap_or(ori_link.link.len());
1662 (ori_link.range.start + after_first_backtick_group)
1663 ..(ori_link.range.start + before_second_backtick_group)
1666 /// Returns true if we should ignore `link` due to it being unlikely
1667 /// that it is an intra-doc link. `link` should still have disambiguators
1668 /// if there were any.
1670 /// The difference between this and [`should_ignore_link()`] is that this
1671 /// check should only be used on links that still have disambiguators.
1672 fn should_ignore_link_with_disambiguators(link: &str) -> bool {
1673 link.contains(|ch: char| !(ch.is_alphanumeric() || ":_<>, !*&;@()".contains(ch)))
1676 /// Returns true if we should ignore `path_str` due to it being unlikely
1677 /// that it is an intra-doc link.
1678 fn should_ignore_link(path_str: &str) -> bool {
1679 path_str.contains(|ch: char| !(ch.is_alphanumeric() || ":_<>, !*&;".contains(ch)))
1682 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1683 /// Disambiguators for a link.
1684 enum Disambiguator {
1687 /// This is buggy, see <https://github.com/rust-lang/rust/pull/77875#discussion_r503583103>
1689 /// `struct@` or `f()`
1692 Namespace(Namespace),
1695 impl Disambiguator {
1696 /// Given a link, parse and return `(disambiguator, path_str, link_text)`.
1698 /// This returns `Ok(Some(...))` if a disambiguator was found,
1699 /// `Ok(None)` if no disambiguator was found, or `Err(...)`
1700 /// if there was a problem with the disambiguator.
1701 fn from_str(link: &str) -> Result<Option<(Self, &str, &str)>, (String, Range<usize>)> {
1702 use Disambiguator::{Kind, Namespace as NS, Primitive};
1704 if let Some(idx) = link.find('@') {
1705 let (prefix, rest) = link.split_at(idx);
1706 let d = match prefix {
1707 "struct" => Kind(DefKind::Struct),
1708 "enum" => Kind(DefKind::Enum),
1709 "trait" => Kind(DefKind::Trait),
1710 "union" => Kind(DefKind::Union),
1711 "module" | "mod" => Kind(DefKind::Mod),
1712 "const" | "constant" => Kind(DefKind::Const),
1713 "static" => Kind(DefKind::Static(Mutability::Not)),
1714 "function" | "fn" | "method" => Kind(DefKind::Fn),
1715 "derive" => Kind(DefKind::Macro(MacroKind::Derive)),
1716 "type" => NS(Namespace::TypeNS),
1717 "value" => NS(Namespace::ValueNS),
1718 "macro" => NS(Namespace::MacroNS),
1719 "prim" | "primitive" => Primitive,
1720 _ => return Err((format!("unknown disambiguator `{}`", prefix), 0..idx)),
1722 Ok(Some((d, &rest[1..], &rest[1..])))
1725 ("!()", DefKind::Macro(MacroKind::Bang)),
1726 ("!{}", DefKind::Macro(MacroKind::Bang)),
1727 ("![]", DefKind::Macro(MacroKind::Bang)),
1728 ("()", DefKind::Fn),
1729 ("!", DefKind::Macro(MacroKind::Bang)),
1731 for (suffix, kind) in suffixes {
1732 if let Some(path_str) = link.strip_suffix(suffix) {
1733 // Avoid turning `!` or `()` into an empty string
1734 if !path_str.is_empty() {
1735 return Ok(Some((Kind(kind), path_str, link)));
1743 fn ns(self) -> Namespace {
1745 Self::Namespace(n) => n,
1747 k.ns().expect("only DefKinds with a valid namespace can be disambiguators")
1749 Self::Primitive => TypeNS,
1753 fn article(self) -> &'static str {
1755 Self::Namespace(_) => panic!("article() doesn't make sense for namespaces"),
1756 Self::Kind(k) => k.article(),
1757 Self::Primitive => "a",
1761 fn descr(self) -> &'static str {
1763 Self::Namespace(n) => n.descr(),
1764 // HACK(jynelson): the source of `DefKind::descr` only uses the DefId for
1765 // printing "module" vs "crate" so using the wrong ID is not a huge problem
1766 Self::Kind(k) => k.descr(CRATE_DEF_ID.to_def_id()),
1767 Self::Primitive => "builtin type",
1772 /// A suggestion to show in a diagnostic.
1775 Prefix(&'static str),
1780 /// `foo` without any disambiguator
1781 RemoveDisambiguator,
1785 fn descr(&self) -> Cow<'static, str> {
1787 Self::Prefix(x) => format!("prefix with `{}@`", x).into(),
1788 Self::Function => "add parentheses".into(),
1789 Self::Macro => "add an exclamation mark".into(),
1790 Self::RemoveDisambiguator => "remove the disambiguator".into(),
1794 fn as_help(&self, path_str: &str) -> String {
1795 // FIXME: if this is an implied shortcut link, it's bad style to suggest `@`
1797 Self::Prefix(prefix) => format!("{}@{}", prefix, path_str),
1798 Self::Function => format!("{}()", path_str),
1799 Self::Macro => format!("{}!", path_str),
1800 Self::RemoveDisambiguator => path_str.into(),
1808 sp: rustc_span::Span,
1809 ) -> Vec<(rustc_span::Span, String)> {
1810 let inner_sp = match ori_link.find('(') {
1811 Some(index) => sp.with_hi(sp.lo() + BytePos(index as _)),
1814 let inner_sp = match ori_link.find('!') {
1815 Some(index) => inner_sp.with_hi(inner_sp.lo() + BytePos(index as _)),
1818 let inner_sp = match ori_link.find('@') {
1819 Some(index) => inner_sp.with_lo(inner_sp.lo() + BytePos(index as u32 + 1)),
1823 Self::Prefix(prefix) => {
1824 // FIXME: if this is an implied shortcut link, it's bad style to suggest `@`
1825 let mut sugg = vec![(sp.with_hi(inner_sp.lo()), format!("{}@", prefix))];
1826 if sp.hi() != inner_sp.hi() {
1827 sugg.push((inner_sp.shrink_to_hi().with_hi(sp.hi()), String::new()));
1832 let mut sugg = vec![(inner_sp.shrink_to_hi().with_hi(sp.hi()), "()".to_string())];
1833 if sp.lo() != inner_sp.lo() {
1834 sugg.push((inner_sp.shrink_to_lo().with_lo(sp.lo()), String::new()));
1839 let mut sugg = vec![(inner_sp.shrink_to_hi(), "!".to_string())];
1840 if sp.lo() != inner_sp.lo() {
1841 sugg.push((inner_sp.shrink_to_lo().with_lo(sp.lo()), String::new()));
1845 Self::RemoveDisambiguator => vec![(sp, path_str.into())],
1850 /// Reports a diagnostic for an intra-doc link.
1852 /// If no link range is provided, or the source span of the link cannot be determined, the span of
1853 /// the entire documentation block is used for the lint. If a range is provided but the span
1854 /// calculation fails, a note is added to the diagnostic pointing to the link in the markdown.
1856 /// The `decorate` callback is invoked in all cases to allow further customization of the
1857 /// diagnostic before emission. If the span of the link was able to be determined, the second
1858 /// parameter of the callback will contain it, and the primary span of the diagnostic will be set
1860 fn report_diagnostic(
1862 lint: &'static Lint,
1864 DiagnosticInfo { item, ori_link: _, dox, link_range }: &DiagnosticInfo<'_>,
1865 decorate: impl FnOnce(&mut Diagnostic, Option<rustc_span::Span>),
1867 let Some(hir_id) = DocContext::as_local_hir_id(tcx, item.def_id)
1869 // If non-local, no need to check anything.
1870 info!("ignoring warning from parent crate: {}", msg);
1874 let sp = item.attr_span(tcx);
1876 tcx.struct_span_lint_hir(lint, hir_id, sp, |lint| {
1877 let mut diag = lint.build(msg);
1880 super::source_span_for_markdown_range(tcx, dox, link_range, &item.attrs).map(|sp| {
1881 if dox.as_bytes().get(link_range.start) == Some(&b'`')
1882 && dox.as_bytes().get(link_range.end - 1) == Some(&b'`')
1884 sp.with_lo(sp.lo() + BytePos(1)).with_hi(sp.hi() - BytePos(1))
1890 if let Some(sp) = span {
1893 // blah blah blah\nblah\nblah [blah] blah blah\nblah blah
1896 // last_new_line_offset
1897 let last_new_line_offset = dox[..link_range.start].rfind('\n').map_or(0, |n| n + 1);
1898 let line = dox[last_new_line_offset..].lines().next().unwrap_or("");
1900 // Print the line containing the `link_range` and manually mark it with '^'s.
1902 "the link appears in this line:\n\n{line}\n\
1903 {indicator: <before$}{indicator:^<found$}",
1906 before = link_range.start - last_new_line_offset,
1907 found = link_range.len(),
1911 decorate(&mut diag, span);
1917 /// Reports a link that failed to resolve.
1919 /// This also tries to resolve any intermediate path segments that weren't
1920 /// handled earlier. For example, if passed `Item::Crate(std)` and `path_str`
1921 /// `std::io::Error::x`, this will resolve `std::io::Error`.
1922 fn resolution_failure(
1923 collector: &mut LinkCollector<'_, '_>,
1924 diag_info: DiagnosticInfo<'_>,
1926 disambiguator: Option<Disambiguator>,
1927 kinds: SmallVec<[ResolutionFailure<'_>; 3]>,
1929 let tcx = collector.cx.tcx;
1932 BROKEN_INTRA_DOC_LINKS,
1933 &format!("unresolved link to `{}`", path_str),
1936 let item = |res: Res| format!("the {} `{}`", res.descr(), res.name(tcx),);
1937 let assoc_item_not_allowed = |res: Res| {
1938 let name = res.name(tcx);
1940 "`{}` is {} {}, not a module or type, and cannot have associated items",
1946 // ignore duplicates
1947 let mut variants_seen = SmallVec::<[_; 3]>::new();
1948 for mut failure in kinds {
1949 let variant = std::mem::discriminant(&failure);
1950 if variants_seen.contains(&variant) {
1953 variants_seen.push(variant);
1955 if let ResolutionFailure::NotResolved {
1964 let item_id = *item_id;
1965 let module_id = *module_id;
1966 // FIXME(jynelson): this might conflict with my `Self` fix in #76467
1967 // FIXME: maybe use itertools `collect_tuple` instead?
1968 fn split(path: &str) -> Option<(&str, &str)> {
1969 let mut splitter = path.rsplitn(2, "::");
1970 splitter.next().and_then(|right| splitter.next().map(|left| (left, right)))
1973 // Check if _any_ parent of the path gets resolved.
1974 // If so, report it and say the first which failed; if not, say the first path segment didn't resolve.
1975 let mut name = path_str;
1977 let Some((start, end)) = split(name) else {
1978 // avoid bug that marked [Quux::Z] as missing Z, not Quux
1979 if partial_res.is_none() {
1980 *unresolved = name.into();
1985 for ns in [TypeNS, ValueNS, MacroNS] {
1987 collector.check_full_res(ns, start, item_id, module_id, &None)
1989 debug!("found partial_res={:?}", res);
1990 *partial_res = Some(res);
1991 *unresolved = end.into();
1995 *unresolved = end.into();
1998 let last_found_module = match *partial_res {
1999 Some(Res::Def(DefKind::Mod, id)) => Some(id),
2000 None => Some(module_id),
2003 // See if this was a module: `[path]` or `[std::io::nope]`
2004 if let Some(module) = last_found_module {
2005 let note = if partial_res.is_some() {
2006 // Part of the link resolved; e.g. `std::io::nonexistent`
2007 let module_name = tcx.item_name(module);
2008 format!("no item named `{}` in module `{}`", unresolved, module_name)
2010 // None of the link resolved; e.g. `Notimported`
2011 format!("no item named `{}` in scope", unresolved)
2013 if let Some(span) = sp {
2014 diag.span_label(span, ¬e);
2019 // If the link has `::` in it, assume it was meant to be an intra-doc link.
2020 // Otherwise, the `[]` might be unrelated.
2021 // FIXME: don't show this for autolinks (`<>`), `()` style links, or reference links
2022 if !path_str.contains("::") {
2023 diag.help(r#"to escape `[` and `]` characters, add '\' before them like `\[` or `\]`"#);
2029 // Otherwise, it must be an associated item or variant
2030 let res = partial_res.expect("None case was handled by `last_found_module`");
2031 let name = res.name(tcx);
2032 let kind = match res {
2033 Res::Def(kind, _) => Some(kind),
2034 Res::Primitive(_) => None,
2036 let path_description = if let Some(kind) = kind {
2038 Mod | ForeignMod => "inner item",
2039 Struct => "field or associated item",
2040 Enum | Union => "variant or associated item",
2058 let note = assoc_item_not_allowed(res);
2059 if let Some(span) = sp {
2060 diag.span_label(span, ¬e);
2066 Trait | TyAlias | ForeignTy | OpaqueTy | TraitAlias | TyParam
2067 | Static(_) => "associated item",
2068 Impl | GlobalAsm => unreachable!("not a path"),
2074 "the {} `{}` has no {} named `{}`",
2077 disambiguator.map_or(path_description, |d| d.descr()),
2080 if let Some(span) = sp {
2081 diag.span_label(span, ¬e);
2088 let note = match failure {
2089 ResolutionFailure::NotResolved { .. } => unreachable!("handled above"),
2090 ResolutionFailure::Dummy => continue,
2091 ResolutionFailure::WrongNamespace { res, expected_ns } => {
2092 suggest_disambiguator(res, diag, path_str, diag_info.ori_link, sp);
2095 "this link resolves to {}, which is not in the {} namespace",
2100 ResolutionFailure::NoParentItem => {
2101 // FIXME(eddyb) this doesn't belong here, whatever made
2102 // the `ResolutionFailure::NoParentItem` should emit an
2103 // immediate or delayed `span_bug` about the issue.
2104 tcx.sess.delay_span_bug(
2105 sp.unwrap_or(DUMMY_SP),
2106 "intra-doc link missing parent item",
2109 "BUG: all intra-doc links should have a parent item".to_owned()
2111 ResolutionFailure::MalformedGenerics(variant) => match variant {
2112 MalformedGenerics::UnbalancedAngleBrackets => {
2113 String::from("unbalanced angle brackets")
2115 MalformedGenerics::MissingType => {
2116 String::from("missing type for generic parameters")
2118 MalformedGenerics::HasFullyQualifiedSyntax => {
2119 diag.note("see https://github.com/rust-lang/rust/issues/74563 for more information");
2120 String::from("fully-qualified syntax is unsupported")
2122 MalformedGenerics::InvalidPathSeparator => {
2123 String::from("has invalid path separator")
2125 MalformedGenerics::TooManyAngleBrackets => {
2126 String::from("too many angle brackets")
2128 MalformedGenerics::EmptyAngleBrackets => {
2129 String::from("empty angle brackets")
2133 if let Some(span) = sp {
2134 diag.span_label(span, ¬e);
2143 /// Report an anchor failure.
2144 fn anchor_failure(cx: &DocContext<'_>, diag_info: DiagnosticInfo<'_>, failure: AnchorFailure) {
2145 let (msg, anchor_idx) = match failure {
2146 AnchorFailure::MultipleAnchors => {
2147 (format!("`{}` contains multiple anchors", diag_info.ori_link), 1)
2149 AnchorFailure::RustdocAnchorConflict(res) => (
2151 "`{}` contains an anchor, but links to {kind}s are already anchored",
2159 report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, &msg, &diag_info, |diag, sp| {
2160 if let Some(mut sp) = sp {
2161 if let Some((fragment_offset, _)) =
2162 diag_info.ori_link.char_indices().filter(|(_, x)| *x == '#').nth(anchor_idx)
2164 sp = sp.with_lo(sp.lo() + BytePos(fragment_offset as _));
2166 diag.span_label(sp, "invalid anchor");
2168 if let AnchorFailure::RustdocAnchorConflict(Res::Primitive(_)) = failure {
2169 if let Some(sp) = sp {
2170 span_bug!(sp, "anchors should be allowed now");
2172 bug!("anchors should be allowed now");
2178 /// Report an error in the link disambiguator.
2179 fn disambiguator_error(
2180 cx: &DocContext<'_>,
2181 mut diag_info: DiagnosticInfo<'_>,
2182 disambiguator_range: Range<usize>,
2185 diag_info.link_range = disambiguator_range;
2186 report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, msg, &diag_info, |diag, _sp| {
2188 "see {}/rustdoc/linking-to-items-by-name.html#namespaces-and-disambiguators for more info about disambiguators",
2189 crate::DOC_RUST_LANG_ORG_CHANNEL
2195 /// Report an ambiguity error, where there were multiple possible resolutions.
2197 cx: &DocContext<'_>,
2198 diag_info: DiagnosticInfo<'_>,
2200 candidates: Vec<Res>,
2202 let mut msg = format!("`{}` is ", path_str);
2204 match candidates.as_slice() {
2205 [first_def, second_def] => {
2207 "both {} {} and {} {}",
2208 first_def.article(),
2210 second_def.article(),
2215 let mut candidates = candidates.iter().peekable();
2216 while let Some(res) = candidates.next() {
2217 if candidates.peek().is_some() {
2218 msg += &format!("{} {}, ", res.article(), res.descr());
2220 msg += &format!("and {} {}", res.article(), res.descr());
2226 report_diagnostic(cx.tcx, BROKEN_INTRA_DOC_LINKS, &msg, &diag_info, |diag, sp| {
2227 if let Some(sp) = sp {
2228 diag.span_label(sp, "ambiguous link");
2230 diag.note("ambiguous link");
2233 for res in candidates {
2234 suggest_disambiguator(res, diag, path_str, diag_info.ori_link, sp);
2239 /// In case of an ambiguity or mismatched disambiguator, suggest the correct
2241 fn suggest_disambiguator(
2243 diag: &mut Diagnostic,
2246 sp: Option<rustc_span::Span>,
2248 let suggestion = res.disambiguator_suggestion();
2249 let help = format!("to link to the {}, {}", res.descr(), suggestion.descr());
2251 if let Some(sp) = sp {
2252 let mut spans = suggestion.as_help_span(path_str, ori_link, sp);
2253 if spans.len() > 1 {
2254 diag.multipart_suggestion(&help, spans, Applicability::MaybeIncorrect);
2256 let (sp, suggestion_text) = spans.pop().unwrap();
2257 diag.span_suggestion_verbose(sp, &help, suggestion_text, Applicability::MaybeIncorrect);
2260 diag.help(&format!("{}: {}", help, suggestion.as_help(path_str)));
2264 /// Report a link from a public item to a private one.
2265 fn privacy_error(cx: &DocContext<'_>, diag_info: &DiagnosticInfo<'_>, path_str: &str) {
2267 let item_name = match diag_info.item.name {
2272 None => "<unknown>",
2275 format!("public documentation for `{}` links to private item `{}`", item_name, path_str);
2277 report_diagnostic(cx.tcx, PRIVATE_INTRA_DOC_LINKS, &msg, diag_info, |diag, sp| {
2278 if let Some(sp) = sp {
2279 diag.span_label(sp, "this item is private");
2282 let note_msg = if cx.render_options.document_private {
2283 "this link resolves only because you passed `--document-private-items`, but will break without"
2285 "this link will resolve properly if you pass `--document-private-items`"
2287 diag.note(note_msg);
2291 /// Given an enum variant's res, return the res of its enum and the associated fragment.
2293 cx: &DocContext<'_>,
2295 ) -> Result<(Res, Option<ItemFragment>), ErrorKind<'static>> {
2297 .parent(res.def_id(cx.tcx))
2299 let parent_def = Res::Def(DefKind::Enum, parent);
2300 let variant = cx.tcx.expect_variant_res(res.as_hir_res().unwrap());
2301 (parent_def, Some(ItemFragment(FragmentKind::Variant, variant.def_id)))
2303 .ok_or_else(|| ResolutionFailure::NoParentItem.into())
2306 /// Resolve a primitive type or value.
2307 fn resolve_primitive(path_str: &str, ns: Namespace) -> Option<Res> {
2311 use PrimitiveType::*;
2312 let prim = match path_str {
2328 "bool" | "true" | "false" => Bool,
2329 "str" | "&str" => Str,
2330 // See #80181 for why these don't have symbols associated.
2335 "pointer" | "*const" | "*mut" => RawPointer,
2336 "reference" | "&" | "&mut" => Reference,
2338 "never" | "!" => Never,
2341 debug!("resolved primitives {:?}", prim);
2342 Some(Res::Primitive(prim))
2345 fn strip_generics_from_path(path_str: &str) -> Result<String, ResolutionFailure<'static>> {
2346 let mut stripped_segments = vec![];
2347 let mut path = path_str.chars().peekable();
2348 let mut segment = Vec::new();
2350 while let Some(chr) = path.next() {
2353 if path.next_if_eq(&':').is_some() {
2354 let stripped_segment =
2355 strip_generics_from_path_segment(mem::take(&mut segment))?;
2356 if !stripped_segment.is_empty() {
2357 stripped_segments.push(stripped_segment);
2360 return Err(ResolutionFailure::MalformedGenerics(
2361 MalformedGenerics::InvalidPathSeparator,
2370 return Err(ResolutionFailure::MalformedGenerics(
2371 MalformedGenerics::TooManyAngleBrackets,
2375 return Err(ResolutionFailure::MalformedGenerics(
2376 MalformedGenerics::EmptyAngleBrackets,
2382 while let Some(chr) = path.next_if(|c| *c != '>') {
2389 _ => segment.push(chr),
2391 trace!("raw segment: {:?}", segment);
2394 if !segment.is_empty() {
2395 let stripped_segment = strip_generics_from_path_segment(segment)?;
2396 if !stripped_segment.is_empty() {
2397 stripped_segments.push(stripped_segment);
2401 debug!("path_str: {:?}\nstripped segments: {:?}", path_str, &stripped_segments);
2403 let stripped_path = stripped_segments.join("::");
2405 if !stripped_path.is_empty() {
2408 Err(ResolutionFailure::MalformedGenerics(MalformedGenerics::MissingType))
2412 fn strip_generics_from_path_segment(
2414 ) -> Result<String, ResolutionFailure<'static>> {
2415 let mut stripped_segment = String::new();
2416 let mut param_depth = 0;
2418 let mut latest_generics_chunk = String::new();
2423 latest_generics_chunk.clear();
2424 } else if c == '>' {
2426 if latest_generics_chunk.contains(" as ") {
2427 // The segment tries to use fully-qualified syntax, which is currently unsupported.
2428 // Give a helpful error message instead of completely ignoring the angle brackets.
2429 return Err(ResolutionFailure::MalformedGenerics(
2430 MalformedGenerics::HasFullyQualifiedSyntax,
2434 if param_depth == 0 {
2435 stripped_segment.push(c);
2437 latest_generics_chunk.push(c);
2442 if param_depth == 0 {
2443 Ok(stripped_segment)
2445 // The segment has unbalanced angle brackets, e.g. `Vec<T` or `Vec<T>>`
2446 Err(ResolutionFailure::MalformedGenerics(MalformedGenerics::UnbalancedAngleBrackets))