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