src/librustdoc/clean/inline.rs

   1 //! Support for inlining external documentation into the current AST.
   2
   3 use std::iter::once;
   4 use std::sync::Arc;
   5
   6 use thin_vec::{thin_vec, ThinVec};
   7
   8 use rustc_ast as ast;
   9 use rustc_data_structures::fx::FxHashSet;
  10 use rustc_hir as hir;
  11 use rustc_hir::def::{DefKind, Res};
  12 use rustc_hir::def_id::{DefId, LocalDefId};
  13 use rustc_hir::Mutability;
  14 use rustc_metadata::creader::{CStore, LoadedMacro};
  15 use rustc_middle::ty::{self, TyCtxt};
  16 use rustc_span::hygiene::MacroKind;
  17 use rustc_span::symbol::{kw, sym, Symbol};
  18
  19 use crate::clean::{
  20     self, clean_fn_decl_from_did_and_sig, clean_generics, clean_impl_item, clean_middle_assoc_item,
  21     clean_middle_field, clean_middle_ty, clean_trait_ref_with_bindings, clean_ty,
  22     clean_ty_generics, clean_variant_def, utils, Attributes, AttributesExt, ImplKind, ItemId, Type,
  23 };
  24 use crate::core::DocContext;
  25 use crate::formats::item_type::ItemType;
  26
  27 /// Attempt to inline a definition into this AST.
  28 ///
  29 /// This function will fetch the definition specified, and if it is
  30 /// from another crate it will attempt to inline the documentation
  31 /// from the other crate into this crate.
  32 ///
  33 /// This is primarily used for `pub use` statements which are, in general,
  34 /// implementation details. Inlining the documentation should help provide a
  35 /// better experience when reading the documentation in this use case.
  36 ///
  37 /// The returned value is `None` if the definition could not be inlined,
  38 /// and `Some` of a vector of items if it was successfully expanded.
  39 ///
  40 /// `parent_module` refers to the parent of the *re-export*, not the original item.
  41 pub(crate) fn try_inline(
  42     cx: &mut DocContext<'_>,
  43     parent_module: DefId,
  44     import_def_id: Option<DefId>,
  45     res: Res,
  46     name: Symbol,
  47     attrs: Option<&[ast::Attribute]>,
  48     visited: &mut FxHashSet<DefId>,
  49 ) -> Option<Vec<clean::Item>> {
  50     let did = res.opt_def_id()?;
  51     if did.is_local() {
  52         return None;
  53     }
  54     let mut ret = Vec::new();
  55
  56     debug!("attrs={:?}", attrs);
  57
  58     let attrs_without_docs = attrs.map(|attrs| {
  59         attrs.into_iter().filter(|a| a.doc_str().is_none()).cloned().collect::<Vec<_>>()
  60     });
  61     // We need this ugly code because:
  62     //
  63     // ```
  64     // attrs_without_docs.map(|a| a.as_slice())
  65     // ```
  66     //
  67     // will fail because it returns a temporary slice and:
  68     //
  69     // ```
  70     // attrs_without_docs.map(|s| {
  71     //     vec = s.as_slice();
  72     //     vec
  73     // })
  74     // ```
  75     //
  76     // will fail because we're moving an uninitialized variable into a closure.
  77     let vec;
  78     let attrs_without_docs = match attrs_without_docs {
  79         Some(s) => {
  80             vec = s;
  81             Some(vec.as_slice())
  82         }
  83         None => None,
  84     };
  85
  86     let kind = match res {
  87         Res::Def(DefKind::Trait, did) => {
  88             record_extern_fqn(cx, did, ItemType::Trait);
  89             build_impls(cx, Some(parent_module), did, attrs_without_docs, &mut ret);
  90             clean::TraitItem(Box::new(build_external_trait(cx, did)))
  91         }
  92         Res::Def(DefKind::Fn, did) => {
  93             record_extern_fqn(cx, did, ItemType::Function);
  94             clean::FunctionItem(build_external_function(cx, did))
  95         }
  96         Res::Def(DefKind::Struct, did) => {
  97             record_extern_fqn(cx, did, ItemType::Struct);
  98             build_impls(cx, Some(parent_module), did, attrs_without_docs, &mut ret);
  99             clean::StructItem(build_struct(cx, did))
 100         }
 101         Res::Def(DefKind::Union, did) => {
 102             record_extern_fqn(cx, did, ItemType::Union);
 103             build_impls(cx, Some(parent_module), did, attrs_without_docs, &mut ret);
 104             clean::UnionItem(build_union(cx, did))
 105         }
 106         Res::Def(DefKind::TyAlias, did) => {
 107             record_extern_fqn(cx, did, ItemType::Typedef);
 108             build_impls(cx, Some(parent_module), did, attrs_without_docs, &mut ret);
 109             clean::TypedefItem(build_type_alias(cx, did))
 110         }
 111         Res::Def(DefKind::Enum, did) => {
 112             record_extern_fqn(cx, did, ItemType::Enum);
 113             build_impls(cx, Some(parent_module), did, attrs_without_docs, &mut ret);
 114             clean::EnumItem(build_enum(cx, did))
 115         }
 116         Res::Def(DefKind::ForeignTy, did) => {
 117             record_extern_fqn(cx, did, ItemType::ForeignType);
 118             build_impls(cx, Some(parent_module), did, attrs_without_docs, &mut ret);
 119             clean::ForeignTypeItem
 120         }
 121         // Never inline enum variants but leave them shown as re-exports.
 122         Res::Def(DefKind::Variant, _) => return None,
 123         // Assume that enum variants and struct types are re-exported next to
 124         // their constructors.
 125         Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) => return Some(Vec::new()),
 126         Res::Def(DefKind::Mod, did) => {
 127             record_extern_fqn(cx, did, ItemType::Module);
 128             clean::ModuleItem(build_module(cx, did, visited))
 129         }
 130         Res::Def(DefKind::Static(_), did) => {
 131             record_extern_fqn(cx, did, ItemType::Static);
 132             clean::StaticItem(build_static(cx, did, cx.tcx.is_mutable_static(did)))
 133         }
 134         Res::Def(DefKind::Const, did) => {
 135             record_extern_fqn(cx, did, ItemType::Constant);
 136             clean::ConstantItem(build_const(cx, did))
 137         }
 138         Res::Def(DefKind::Macro(kind), did) => {
 139             let mac = build_macro(cx, did, name, import_def_id);
 140
 141             let type_kind = match kind {
 142                 MacroKind::Bang => ItemType::Macro,
 143                 MacroKind::Attr => ItemType::ProcAttribute,
 144                 MacroKind::Derive => ItemType::ProcDerive,
 145             };
 146             record_extern_fqn(cx, did, type_kind);
 147             mac
 148         }
 149         _ => return None,
 150     };
 151
 152     let (attrs, cfg) = merge_attrs(cx, Some(parent_module), load_attrs(cx, did), attrs);
 153     cx.inlined.insert(did.into());
 154     let mut item =
 155         clean::Item::from_def_id_and_attrs_and_parts(did, Some(name), kind, Box::new(attrs), cfg);
 156     // The visibility needs to reflect the one from the reexport and not from the "source" DefId.
 157     item.inline_stmt_id = import_def_id;
 158     ret.push(item);
 159     Some(ret)
 160 }
 161
 162 pub(crate) fn try_inline_glob(
 163     cx: &mut DocContext<'_>,
 164     res: Res,
 165     current_mod: LocalDefId,
 166     visited: &mut FxHashSet<DefId>,
 167     inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
 168 ) -> Option<Vec<clean::Item>> {
 169     let did = res.opt_def_id()?;
 170     if did.is_local() {
 171         return None;
 172     }
 173
 174     match res {
 175         Res::Def(DefKind::Mod, did) => {
 176             // Use the set of module reexports to filter away names that are not actually
 177             // reexported by the glob, e.g. because they are shadowed by something else.
 178             let reexports = cx
 179                 .tcx
 180                 .module_reexports(current_mod)
 181                 .unwrap_or_default()
 182                 .iter()
 183                 .filter_map(|child| child.res.opt_def_id())
 184                 .collect();
 185             let mut items = build_module_items(cx, did, visited, inlined_names, Some(&reexports));
 186             items.drain_filter(|item| {
 187                 if let Some(name) = item.name {
 188                     // If an item with the same type and name already exists,
 189                     // it takes priority over the inlined stuff.
 190                     !inlined_names.insert((item.type_(), name))
 191                 } else {
 192                     false
 193                 }
 194             });
 195             Some(items)
 196         }
 197         // glob imports on things like enums aren't inlined even for local exports, so just bail
 198         _ => None,
 199     }
 200 }
 201
 202 pub(crate) fn load_attrs<'hir>(cx: &DocContext<'hir>, did: DefId) -> &'hir [ast::Attribute] {
 203     cx.tcx.get_attrs_unchecked(did)
 204 }
 205
 206 /// Record an external fully qualified name in the external_paths cache.
 207 ///
 208 /// These names are used later on by HTML rendering to generate things like
 209 /// source links back to the original item.
 210 pub(crate) fn record_extern_fqn(cx: &mut DocContext<'_>, did: DefId, kind: ItemType) {
 211     let crate_name = cx.tcx.crate_name(did.krate);
 212
 213     let relative =
 214         cx.tcx.def_path(did).data.into_iter().filter_map(|elem| elem.data.get_opt_name());
 215     let fqn = if let ItemType::Macro = kind {
 216         // Check to see if it is a macro 2.0 or built-in macro
 217         if matches!(
 218             CStore::from_tcx(cx.tcx).load_macro_untracked(did, cx.sess()),
 219             LoadedMacro::MacroDef(def, _)
 220                 if matches!(&def.kind, ast::ItemKind::MacroDef(ast_def)
 221                     if !ast_def.macro_rules)
 222         ) {
 223             once(crate_name).chain(relative).collect()
 224         } else {
 225             vec![crate_name, relative.last().expect("relative was empty")]
 226         }
 227     } else {
 228         once(crate_name).chain(relative).collect()
 229     };
 230
 231     if did.is_local() {
 232         cx.cache.exact_paths.insert(did, fqn);
 233     } else {
 234         cx.cache.external_paths.insert(did, (fqn, kind));
 235     }
 236 }
 237
 238 pub(crate) fn build_external_trait(cx: &mut DocContext<'_>, did: DefId) -> clean::Trait {
 239     let trait_items = cx
 240         .tcx
 241         .associated_items(did)
 242         .in_definition_order()
 243         .map(|item| clean_middle_assoc_item(item, cx))
 244         .collect();
 245
 246     let predicates = cx.tcx.predicates_of(did);
 247     let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
 248     let generics = filter_non_trait_generics(did, generics);
 249     let (generics, supertrait_bounds) = separate_supertrait_bounds(generics);
 250     clean::Trait { def_id: did, generics, items: trait_items, bounds: supertrait_bounds }
 251 }
 252
 253 fn build_external_function<'tcx>(cx: &mut DocContext<'tcx>, did: DefId) -> Box<clean::Function> {
 254     let sig = cx.tcx.fn_sig(did);
 255
 256     let late_bound_regions = sig.bound_vars().into_iter().filter_map(|var| match var {
 257         ty::BoundVariableKind::Region(ty::BrNamed(_, name)) if name != kw::UnderscoreLifetime => {
 258             Some(clean::GenericParamDef::lifetime(name))
 259         }
 260         _ => None,
 261     });
 262
 263     let predicates = cx.tcx.explicit_predicates_of(did);
 264     let (generics, decl) = clean::enter_impl_trait(cx, |cx| {
 265         // NOTE: generics need to be cleaned before the decl!
 266         let mut generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
 267         // FIXME: This does not place parameters in source order (late-bound ones come last)
 268         generics.params.extend(late_bound_regions);
 269         let decl = clean_fn_decl_from_did_and_sig(cx, Some(did), sig);
 270         (generics, decl)
 271     });
 272     Box::new(clean::Function { decl, generics })
 273 }
 274
 275 fn build_enum(cx: &mut DocContext<'_>, did: DefId) -> clean::Enum {
 276     let predicates = cx.tcx.explicit_predicates_of(did);
 277
 278     clean::Enum {
 279         generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
 280         variants: cx.tcx.adt_def(did).variants().iter().map(|v| clean_variant_def(v, cx)).collect(),
 281     }
 282 }
 283
 284 fn build_struct(cx: &mut DocContext<'_>, did: DefId) -> clean::Struct {
 285     let predicates = cx.tcx.explicit_predicates_of(did);
 286     let variant = cx.tcx.adt_def(did).non_enum_variant();
 287
 288     clean::Struct {
 289         ctor_kind: variant.ctor_kind(),
 290         generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
 291         fields: variant.fields.iter().map(|x| clean_middle_field(x, cx)).collect(),
 292     }
 293 }
 294
 295 fn build_union(cx: &mut DocContext<'_>, did: DefId) -> clean::Union {
 296     let predicates = cx.tcx.explicit_predicates_of(did);
 297     let variant = cx.tcx.adt_def(did).non_enum_variant();
 298
 299     let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
 300     let fields = variant.fields.iter().map(|x| clean_middle_field(x, cx)).collect();
 301     clean::Union { generics, fields }
 302 }
 303
 304 fn build_type_alias(cx: &mut DocContext<'_>, did: DefId) -> Box<clean::Typedef> {
 305     let predicates = cx.tcx.explicit_predicates_of(did);
 306     let type_ = clean_middle_ty(ty::Binder::dummy(cx.tcx.type_of(did)), cx, Some(did));
 307
 308     Box::new(clean::Typedef {
 309         type_,
 310         generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
 311         item_type: None,
 312     })
 313 }
 314
 315 /// Builds all inherent implementations of an ADT (struct/union/enum) or Trait item/path/reexport.
 316 pub(crate) fn build_impls(
 317     cx: &mut DocContext<'_>,
 318     parent_module: Option<DefId>,
 319     did: DefId,
 320     attrs: Option<&[ast::Attribute]>,
 321     ret: &mut Vec<clean::Item>,
 322 ) {
 323     let _prof_timer = cx.tcx.sess.prof.generic_activity("build_inherent_impls");
 324     let tcx = cx.tcx;
 325
 326     // for each implementation of an item represented by `did`, build the clean::Item for that impl
 327     for &did in tcx.inherent_impls(did).iter() {
 328         build_impl(cx, parent_module, did, attrs, ret);
 329     }
 330
 331     // This pretty much exists expressly for `dyn Error` traits that exist in the `alloc` crate.
 332     // See also:
 333     //
 334     // * https://github.com/rust-lang/rust/issues/103170 — where it didn't used to get documented
 335     // * https://github.com/rust-lang/rust/pull/99917 — where the feature got used
 336     // * https://github.com/rust-lang/rust/issues/53487 — overall tracking issue for Error
 337     if tcx.has_attr(did, sym::rustc_has_incoherent_inherent_impls) {
 338         use rustc_middle::ty::fast_reject::SimplifiedType::*;
 339         let type_ =
 340             if tcx.is_trait(did) { TraitSimplifiedType(did) } else { AdtSimplifiedType(did) };
 341         for &did in tcx.incoherent_impls(type_) {
 342             build_impl(cx, parent_module, did, attrs, ret);
 343         }
 344     }
 345 }
 346
 347 /// `parent_module` refers to the parent of the re-export, not the original item
 348 pub(crate) fn merge_attrs(
 349     cx: &mut DocContext<'_>,
 350     parent_module: Option<DefId>,
 351     old_attrs: &[ast::Attribute],
 352     new_attrs: Option<&[ast::Attribute]>,
 353 ) -> (clean::Attributes, Option<Arc<clean::cfg::Cfg>>) {
 354     // NOTE: If we have additional attributes (from a re-export),
 355     // always insert them first. This ensure that re-export
 356     // doc comments show up before the original doc comments
 357     // when we render them.
 358     if let Some(inner) = new_attrs {
 359         let mut both = inner.to_vec();
 360         both.extend_from_slice(old_attrs);
 361         (
 362             if let Some(new_id) = parent_module {
 363                 Attributes::from_ast_with_additional(old_attrs, (inner, new_id))
 364             } else {
 365                 Attributes::from_ast(&both)
 366             },
 367             both.cfg(cx.tcx, &cx.cache.hidden_cfg),
 368         )
 369     } else {
 370         (Attributes::from_ast(&old_attrs), old_attrs.cfg(cx.tcx, &cx.cache.hidden_cfg))
 371     }
 372 }
 373
 374 /// Inline an `impl`, inherent or of a trait. The `did` must be for an `impl`.
 375 pub(crate) fn build_impl(
 376     cx: &mut DocContext<'_>,
 377     parent_module: Option<DefId>,
 378     did: DefId,
 379     attrs: Option<&[ast::Attribute]>,
 380     ret: &mut Vec<clean::Item>,
 381 ) {
 382     if !cx.inlined.insert(did.into()) {
 383         return;
 384     }
 385
 386     let _prof_timer = cx.tcx.sess.prof.generic_activity("build_impl");
 387
 388     let tcx = cx.tcx;
 389     let associated_trait = tcx.impl_trait_ref(did).map(ty::EarlyBinder::skip_binder);
 390
 391     // Only inline impl if the implemented trait is
 392     // reachable in rustdoc generated documentation
 393     if !did.is_local() {
 394         if let Some(traitref) = associated_trait {
 395             let did = traitref.def_id;
 396             if !cx.cache.effective_visibilities.is_directly_public(tcx, did) {
 397                 return;
 398             }
 399
 400             if let Some(stab) = tcx.lookup_stability(did) {
 401                 if stab.is_unstable() && stab.feature == sym::rustc_private {
 402                     return;
 403                 }
 404             }
 405         }
 406     }
 407
 408     let impl_item = match did.as_local() {
 409         Some(did) => match &tcx.hir().expect_item(did).kind {
 410             hir::ItemKind::Impl(impl_) => Some(impl_),
 411             _ => panic!("`DefID` passed to `build_impl` is not an `impl"),
 412         },
 413         None => None,
 414     };
 415
 416     let for_ = match &impl_item {
 417         Some(impl_) => clean_ty(impl_.self_ty, cx),
 418         None => clean_middle_ty(ty::Binder::dummy(tcx.type_of(did)), cx, Some(did)),
 419     };
 420
 421     // Only inline impl if the implementing type is
 422     // reachable in rustdoc generated documentation
 423     if !did.is_local() {
 424         if let Some(did) = for_.def_id(&cx.cache) {
 425             if !cx.cache.effective_visibilities.is_directly_public(tcx, did) {
 426                 return;
 427             }
 428
 429             if let Some(stab) = tcx.lookup_stability(did) {
 430                 if stab.is_unstable() && stab.feature == sym::rustc_private {
 431                     return;
 432                 }
 433             }
 434         }
 435     }
 436
 437     let document_hidden = cx.render_options.document_hidden;
 438     let predicates = tcx.explicit_predicates_of(did);
 439     let (trait_items, generics) = match impl_item {
 440         Some(impl_) => (
 441             impl_
 442                 .items
 443                 .iter()
 444                 .map(|item| tcx.hir().impl_item(item.id))
 445                 .filter(|item| {
 446                     // Filter out impl items whose corresponding trait item has `doc(hidden)`
 447                     // not to document such impl items.
 448                     // For inherent impls, we don't do any filtering, because that's already done in strip_hidden.rs.
 449
 450                     // When `--document-hidden-items` is passed, we don't
 451                     // do any filtering, too.
 452                     if document_hidden {
 453                         return true;
 454                     }
 455                     if let Some(associated_trait) = associated_trait {
 456                         let assoc_kind = match item.kind {
 457                             hir::ImplItemKind::Const(..) => ty::AssocKind::Const,
 458                             hir::ImplItemKind::Fn(..) => ty::AssocKind::Fn,
 459                             hir::ImplItemKind::Type(..) => ty::AssocKind::Type,
 460                         };
 461                         let trait_item = tcx
 462                             .associated_items(associated_trait.def_id)
 463                             .find_by_name_and_kind(
 464                                 tcx,
 465                                 item.ident,
 466                                 assoc_kind,
 467                                 associated_trait.def_id,
 468                             )
 469                             .unwrap(); // SAFETY: For all impl items there exists trait item that has the same name.
 470                         !tcx.is_doc_hidden(trait_item.def_id)
 471                     } else {
 472                         true
 473                     }
 474                 })
 475                 .map(|item| clean_impl_item(item, cx))
 476                 .collect::<Vec<_>>(),
 477             clean_generics(impl_.generics, cx),
 478         ),
 479         None => (
 480             tcx.associated_items(did)
 481                 .in_definition_order()
 482                 .filter(|item| {
 483                     // If this is a trait impl, filter out associated items whose corresponding item
 484                     // in the associated trait is marked `doc(hidden)`.
 485                     // If this is an inherent impl, filter out private associated items.
 486                     if let Some(associated_trait) = associated_trait {
 487                         let trait_item = tcx
 488                             .associated_items(associated_trait.def_id)
 489                             .find_by_name_and_kind(
 490                                 tcx,
 491                                 item.ident(tcx),
 492                                 item.kind,
 493                                 associated_trait.def_id,
 494                             )
 495                             .unwrap(); // corresponding associated item has to exist
 496                         !tcx.is_doc_hidden(trait_item.def_id)
 497                     } else {
 498                         item.visibility(tcx).is_public()
 499                     }
 500                 })
 501                 .map(|item| clean_middle_assoc_item(item, cx))
 502                 .collect::<Vec<_>>(),
 503             clean::enter_impl_trait(cx, |cx| {
 504                 clean_ty_generics(cx, tcx.generics_of(did), predicates)
 505             }),
 506         ),
 507     };
 508     let polarity = tcx.impl_polarity(did);
 509     let trait_ = associated_trait
 510         .map(|t| clean_trait_ref_with_bindings(cx, ty::Binder::dummy(t), ThinVec::new()));
 511     if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
 512         super::build_deref_target_impls(cx, &trait_items, ret);
 513     }
 514
 515     // Return if the trait itself or any types of the generic parameters are doc(hidden).
 516     let mut stack: Vec<&Type> = vec![&for_];
 517
 518     if let Some(did) = trait_.as_ref().map(|t| t.def_id()) {
 519         if tcx.is_doc_hidden(did) {
 520             return;
 521         }
 522     }
 523     if let Some(generics) = trait_.as_ref().and_then(|t| t.generics()) {
 524         stack.extend(generics);
 525     }
 526
 527     while let Some(ty) = stack.pop() {
 528         if let Some(did) = ty.def_id(&cx.cache) {
 529             if tcx.is_doc_hidden(did) {
 530                 return;
 531             }
 532         }
 533         if let Some(generics) = ty.generics() {
 534             stack.extend(generics);
 535         }
 536     }
 537
 538     if let Some(did) = trait_.as_ref().map(|t| t.def_id()) {
 539         record_extern_trait(cx, did);
 540     }
 541
 542     let (merged_attrs, cfg) = merge_attrs(cx, parent_module, load_attrs(cx, did), attrs);
 543     trace!("merged_attrs={:?}", merged_attrs);
 544
 545     trace!(
 546         "build_impl: impl {:?} for {:?}",
 547         trait_.as_ref().map(|t| t.def_id()),
 548         for_.def_id(&cx.cache)
 549     );
 550     ret.push(clean::Item::from_def_id_and_attrs_and_parts(
 551         did,
 552         None,
 553         clean::ImplItem(Box::new(clean::Impl {
 554             unsafety: hir::Unsafety::Normal,
 555             generics,
 556             trait_,
 557             for_,
 558             items: trait_items,
 559             polarity,
 560             kind: if utils::has_doc_flag(tcx, did, sym::fake_variadic) {
 561                 ImplKind::FakeVaradic
 562             } else {
 563                 ImplKind::Normal
 564             },
 565         })),
 566         Box::new(merged_attrs),
 567         cfg,
 568     ));
 569 }
 570
 571 fn build_module(
 572     cx: &mut DocContext<'_>,
 573     did: DefId,
 574     visited: &mut FxHashSet<DefId>,
 575 ) -> clean::Module {
 576     let items = build_module_items(cx, did, visited, &mut FxHashSet::default(), None);
 577
 578     let span = clean::Span::new(cx.tcx.def_span(did));
 579     clean::Module { items, span }
 580 }
 581
 582 fn build_module_items(
 583     cx: &mut DocContext<'_>,
 584     did: DefId,
 585     visited: &mut FxHashSet<DefId>,
 586     inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
 587     allowed_def_ids: Option<&FxHashSet<DefId>>,
 588 ) -> Vec<clean::Item> {
 589     let mut items = Vec::new();
 590
 591     // If we're re-exporting a re-export it may actually re-export something in
 592     // two namespaces, so the target may be listed twice. Make sure we only
 593     // visit each node at most once.
 594     for &item in cx.tcx.module_children(did).iter() {
 595         if item.vis.is_public() {
 596             let res = item.res.expect_non_local();
 597             if let Some(def_id) = res.opt_def_id()
 598                 && let Some(allowed_def_ids) = allowed_def_ids
 599                 && !allowed_def_ids.contains(&def_id) {
 600                 continue;
 601             }
 602             if let Some(def_id) = res.mod_def_id() {
 603                 // If we're inlining a glob import, it's possible to have
 604                 // two distinct modules with the same name. We don't want to
 605                 // inline it, or mark any of its contents as visited.
 606                 if did == def_id
 607                     || inlined_names.contains(&(ItemType::Module, item.ident.name))
 608                     || !visited.insert(def_id)
 609                 {
 610                     continue;
 611                 }
 612             }
 613             if let Res::PrimTy(p) = res {
 614                 // Primitive types can't be inlined so generate an import instead.
 615                 let prim_ty = clean::PrimitiveType::from(p);
 616                 items.push(clean::Item {
 617                     name: None,
 618                     attrs: Box::new(clean::Attributes::default()),
 619                     // We can use the item's `DefId` directly since the only information ever used
 620                     // from it is `DefId.krate`.
 621                     item_id: ItemId::DefId(did),
 622                     kind: Box::new(clean::ImportItem(clean::Import::new_simple(
 623                         item.ident.name,
 624                         clean::ImportSource {
 625                             path: clean::Path {
 626                                 res,
 627                                 segments: thin_vec![clean::PathSegment {
 628                                     name: prim_ty.as_sym(),
 629                                     args: clean::GenericArgs::AngleBracketed {
 630                                         args: Default::default(),
 631                                         bindings: ThinVec::new(),
 632                                     },
 633                                 }],
 634                             },
 635                             did: None,
 636                         },
 637                         true,
 638                     ))),
 639                     cfg: None,
 640                     inline_stmt_id: None,
 641                 });
 642             } else if let Some(i) = try_inline(cx, did, None, res, item.ident.name, None, visited) {
 643                 items.extend(i)
 644             }
 645         }
 646     }
 647
 648     items
 649 }
 650
 651 pub(crate) fn print_inlined_const(tcx: TyCtxt<'_>, did: DefId) -> String {
 652     if let Some(did) = did.as_local() {
 653         let hir_id = tcx.hir().local_def_id_to_hir_id(did);
 654         rustc_hir_pretty::id_to_string(&tcx.hir(), hir_id)
 655     } else {
 656         tcx.rendered_const(did).clone()
 657     }
 658 }
 659
 660 fn build_const(cx: &mut DocContext<'_>, def_id: DefId) -> clean::Constant {
 661     clean::Constant {
 662         type_: clean_middle_ty(ty::Binder::dummy(cx.tcx.type_of(def_id)), cx, Some(def_id)),
 663         kind: clean::ConstantKind::Extern { def_id },
 664     }
 665 }
 666
 667 fn build_static(cx: &mut DocContext<'_>, did: DefId, mutable: bool) -> clean::Static {
 668     clean::Static {
 669         type_: clean_middle_ty(ty::Binder::dummy(cx.tcx.type_of(did)), cx, Some(did)),
 670         mutability: if mutable { Mutability::Mut } else { Mutability::Not },
 671         expr: None,
 672     }
 673 }
 674
 675 fn build_macro(
 676     cx: &mut DocContext<'_>,
 677     def_id: DefId,
 678     name: Symbol,
 679     import_def_id: Option<DefId>,
 680 ) -> clean::ItemKind {
 681     match CStore::from_tcx(cx.tcx).load_macro_untracked(def_id, cx.sess()) {
 682         LoadedMacro::MacroDef(item_def, _) => {
 683             if let ast::ItemKind::MacroDef(ref def) = item_def.kind {
 684                 let vis = cx.tcx.visibility(import_def_id.unwrap_or(def_id));
 685                 clean::MacroItem(clean::Macro {
 686                     source: utils::display_macro_source(cx, name, def, def_id, vis),
 687                 })
 688             } else {
 689                 unreachable!()
 690             }
 691         }
 692         LoadedMacro::ProcMacro(ext) => clean::ProcMacroItem(clean::ProcMacro {
 693             kind: ext.macro_kind(),
 694             helpers: ext.helper_attrs,
 695         }),
 696     }
 697 }
 698
 699 /// A trait's generics clause actually contains all of the predicates for all of
 700 /// its associated types as well. We specifically move these clauses to the
 701 /// associated types instead when displaying, so when we're generating the
 702 /// generics for the trait itself we need to be sure to remove them.
 703 /// We also need to remove the implied "recursive" Self: Trait bound.
 704 ///
 705 /// The inverse of this filtering logic can be found in the `Clean`
 706 /// implementation for `AssociatedType`
 707 fn filter_non_trait_generics(trait_did: DefId, mut g: clean::Generics) -> clean::Generics {
 708     for pred in &mut g.where_predicates {
 709         match *pred {
 710             clean::WherePredicate::BoundPredicate {
 711                 ty: clean::Generic(ref s),
 712                 ref mut bounds,
 713                 ..
 714             } if *s == kw::SelfUpper => {
 715                 bounds.retain(|bound| match bound {
 716                     clean::GenericBound::TraitBound(clean::PolyTrait { trait_, .. }, _) => {
 717                         trait_.def_id() != trait_did
 718                     }
 719                     _ => true,
 720                 });
 721             }
 722             _ => {}
 723         }
 724     }
 725
 726     g.where_predicates.retain(|pred| match pred {
 727         clean::WherePredicate::BoundPredicate {
 728             ty: clean::QPath(box clean::QPathData { self_type: clean::Generic(ref s), trait_, .. }),
 729             bounds,
 730             ..
 731         } => !(bounds.is_empty() || *s == kw::SelfUpper && trait_.def_id() == trait_did),
 732         _ => true,
 733     });
 734     g
 735 }
 736
 737 /// Supertrait bounds for a trait are also listed in the generics coming from
 738 /// the metadata for a crate, so we want to separate those out and create a new
 739 /// list of explicit supertrait bounds to render nicely.
 740 fn separate_supertrait_bounds(
 741     mut g: clean::Generics,
 742 ) -> (clean::Generics, Vec<clean::GenericBound>) {
 743     let mut ty_bounds = Vec::new();
 744     g.where_predicates.retain(|pred| match *pred {
 745         clean::WherePredicate::BoundPredicate { ty: clean::Generic(ref s), ref bounds, .. }
 746             if *s == kw::SelfUpper =>
 747         {
 748             ty_bounds.extend(bounds.iter().cloned());
 749             false
 750         }
 751         _ => true,
 752     });
 753     (g, ty_bounds)
 754 }
 755
 756 pub(crate) fn record_extern_trait(cx: &mut DocContext<'_>, did: DefId) {
 757     if did.is_local() {
 758         return;
 759     }
 760
 761     {
 762         if cx.external_traits.borrow().contains_key(&did) || cx.active_extern_traits.contains(&did)
 763         {
 764             return;
 765         }
 766     }
 767
 768     {
 769         cx.active_extern_traits.insert(did);
 770     }
 771
 772     debug!("record_extern_trait: {:?}", did);
 773     let trait_ = build_external_trait(cx, did);
 774
 775     cx.external_traits.borrow_mut().insert(did, trait_);
 776     cx.active_extern_traits.remove(&did);
 777 }