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 rustc_ast as ast;
   7 use rustc_data_structures::fx::FxHashSet;
   8 use rustc_data_structures::thin_vec::ThinVec;
   9 use rustc_hir as hir;
  10 use rustc_hir::def::{DefKind, Res};
  11 use rustc_hir::def_id::DefId;
  12 use rustc_hir::Mutability;
  13 use rustc_metadata::creader::{CStore, LoadedMacro};
  14 use rustc_middle::ty::{self, TyCtxt};
  15 use rustc_span::hygiene::MacroKind;
  16 use rustc_span::symbol::{kw, sym, Symbol};
  17
  18 use crate::clean::{
  19     self, clean_fn_decl_from_did_and_sig, clean_ty_generics, utils, Attributes, AttributesExt,
  20     Clean, ImplKind, ItemId, Type, Visibility,
  21 };
  22 use crate::core::DocContext;
  23 use crate::formats::item_type::ItemType;
  24
  25 type Attrs<'hir> = rustc_middle::ty::Attributes<'hir>;
  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 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<Attrs<'_>>,
  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     let attrs_clone = attrs;
  58
  59     let kind = match res {
  60         Res::Def(DefKind::Trait, did) => {
  61             record_extern_fqn(cx, did, ItemType::Trait);
  62             build_impls(cx, Some(parent_module), did, attrs, &mut ret);
  63             clean::TraitItem(build_external_trait(cx, did))
  64         }
  65         Res::Def(DefKind::Fn, did) => {
  66             record_extern_fqn(cx, did, ItemType::Function);
  67             clean::FunctionItem(build_external_function(cx, did))
  68         }
  69         Res::Def(DefKind::Struct, did) => {
  70             record_extern_fqn(cx, did, ItemType::Struct);
  71             build_impls(cx, Some(parent_module), did, attrs, &mut ret);
  72             clean::StructItem(build_struct(cx, did))
  73         }
  74         Res::Def(DefKind::Union, did) => {
  75             record_extern_fqn(cx, did, ItemType::Union);
  76             build_impls(cx, Some(parent_module), did, attrs, &mut ret);
  77             clean::UnionItem(build_union(cx, did))
  78         }
  79         Res::Def(DefKind::TyAlias, did) => {
  80             record_extern_fqn(cx, did, ItemType::Typedef);
  81             build_impls(cx, Some(parent_module), did, attrs, &mut ret);
  82             clean::TypedefItem(build_type_alias(cx, did), false)
  83         }
  84         Res::Def(DefKind::Enum, did) => {
  85             record_extern_fqn(cx, did, ItemType::Enum);
  86             build_impls(cx, Some(parent_module), did, attrs, &mut ret);
  87             clean::EnumItem(build_enum(cx, did))
  88         }
  89         Res::Def(DefKind::ForeignTy, did) => {
  90             record_extern_fqn(cx, did, ItemType::ForeignType);
  91             build_impls(cx, Some(parent_module), did, attrs, &mut ret);
  92             clean::ForeignTypeItem
  93         }
  94         // Never inline enum variants but leave them shown as re-exports.
  95         Res::Def(DefKind::Variant, _) => return None,
  96         // Assume that enum variants and struct types are re-exported next to
  97         // their constructors.
  98         Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) => return Some(Vec::new()),
  99         Res::Def(DefKind::Mod, did) => {
 100             record_extern_fqn(cx, did, ItemType::Module);
 101             clean::ModuleItem(build_module(cx, did, visited))
 102         }
 103         Res::Def(DefKind::Static(_), did) => {
 104             record_extern_fqn(cx, did, ItemType::Static);
 105             clean::StaticItem(build_static(cx, did, cx.tcx.is_mutable_static(did)))
 106         }
 107         Res::Def(DefKind::Const, did) => {
 108             record_extern_fqn(cx, did, ItemType::Constant);
 109             clean::ConstantItem(build_const(cx, did))
 110         }
 111         Res::Def(DefKind::Macro(kind), did) => {
 112             let mac = build_macro(cx, did, name, import_def_id);
 113
 114             let type_kind = match kind {
 115                 MacroKind::Bang => ItemType::Macro,
 116                 MacroKind::Attr => ItemType::ProcAttribute,
 117                 MacroKind::Derive => ItemType::ProcDerive,
 118             };
 119             record_extern_fqn(cx, did, type_kind);
 120             mac
 121         }
 122         _ => return None,
 123     };
 124
 125     let (attrs, cfg) = merge_attrs(cx, Some(parent_module), load_attrs(cx, did), attrs_clone);
 126     cx.inlined.insert(did.into());
 127     let mut item =
 128         clean::Item::from_def_id_and_attrs_and_parts(did, Some(name), kind, box attrs, cx, cfg);
 129     if let Some(import_def_id) = import_def_id {
 130         // The visibility needs to reflect the one from the reexport and not from the "source" DefId.
 131         item.visibility = cx.tcx.visibility(import_def_id).clean(cx);
 132     }
 133     ret.push(item);
 134     Some(ret)
 135 }
 136
 137 crate fn try_inline_glob(
 138     cx: &mut DocContext<'_>,
 139     res: Res,
 140     visited: &mut FxHashSet<DefId>,
 141 ) -> Option<Vec<clean::Item>> {
 142     let did = res.opt_def_id()?;
 143     if did.is_local() {
 144         return None;
 145     }
 146
 147     match res {
 148         Res::Def(DefKind::Mod, did) => {
 149             let m = build_module(cx, did, visited);
 150             Some(m.items)
 151         }
 152         // glob imports on things like enums aren't inlined even for local exports, so just bail
 153         _ => None,
 154     }
 155 }
 156
 157 crate fn load_attrs<'hir>(cx: &DocContext<'hir>, did: DefId) -> Attrs<'hir> {
 158     cx.tcx.get_attrs(did)
 159 }
 160
 161 /// Record an external fully qualified name in the external_paths cache.
 162 ///
 163 /// These names are used later on by HTML rendering to generate things like
 164 /// source links back to the original item.
 165 crate fn record_extern_fqn(cx: &mut DocContext<'_>, did: DefId, kind: ItemType) {
 166     let crate_name = cx.tcx.crate_name(did.krate);
 167
 168     let relative =
 169         cx.tcx.def_path(did).data.into_iter().filter_map(|elem| elem.data.get_opt_name());
 170     let fqn = if let ItemType::Macro = kind {
 171         // Check to see if it is a macro 2.0 or built-in macro
 172         if matches!(
 173             CStore::from_tcx(cx.tcx).load_macro_untracked(did, cx.sess()),
 174             LoadedMacro::MacroDef(def, _)
 175                 if matches!(&def.kind, ast::ItemKind::MacroDef(ast_def)
 176                     if !ast_def.macro_rules)
 177         ) {
 178             once(crate_name).chain(relative).collect()
 179         } else {
 180             vec![crate_name, relative.last().expect("relative was empty")]
 181         }
 182     } else {
 183         once(crate_name).chain(relative).collect()
 184     };
 185
 186     if did.is_local() {
 187         cx.cache.exact_paths.insert(did, fqn);
 188     } else {
 189         cx.cache.external_paths.insert(did, (fqn, kind));
 190     }
 191 }
 192
 193 crate fn build_external_trait(cx: &mut DocContext<'_>, did: DefId) -> clean::Trait {
 194     let trait_items = cx
 195         .tcx
 196         .associated_items(did)
 197         .in_definition_order()
 198         .map(|item| {
 199             // When building an external trait, the cleaned trait will have all items public,
 200             // which causes methods to have a `pub` prefix, which is invalid since items in traits
 201             // can not have a visibility prefix. Thus we override the visibility here manually.
 202             // See https://github.com/rust-lang/rust/issues/81274
 203             clean::Item { visibility: Visibility::Inherited, ..item.clean(cx) }
 204         })
 205         .collect();
 206
 207     let predicates = cx.tcx.predicates_of(did);
 208     let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
 209     let generics = filter_non_trait_generics(did, generics);
 210     let (generics, supertrait_bounds) = separate_supertrait_bounds(generics);
 211     let is_auto = cx.tcx.trait_is_auto(did);
 212     clean::Trait {
 213         unsafety: cx.tcx.trait_def(did).unsafety,
 214         generics,
 215         items: trait_items,
 216         bounds: supertrait_bounds,
 217         is_auto,
 218     }
 219 }
 220
 221 fn build_external_function(cx: &mut DocContext<'_>, did: DefId) -> clean::Function {
 222     let sig = cx.tcx.fn_sig(did);
 223
 224     let predicates = cx.tcx.predicates_of(did);
 225     let (generics, decl) = clean::enter_impl_trait(cx, |cx| {
 226         // NOTE: generics need to be cleaned before the decl!
 227         let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
 228         let decl = clean_fn_decl_from_did_and_sig(cx, Some(did), sig);
 229         (generics, decl)
 230     });
 231     clean::Function { decl, generics }
 232 }
 233
 234 fn build_enum(cx: &mut DocContext<'_>, did: DefId) -> clean::Enum {
 235     let predicates = cx.tcx.explicit_predicates_of(did);
 236
 237     clean::Enum {
 238         generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
 239         variants_stripped: false,
 240         variants: cx.tcx.adt_def(did).variants().iter().map(|v| v.clean(cx)).collect(),
 241     }
 242 }
 243
 244 fn build_struct(cx: &mut DocContext<'_>, did: DefId) -> clean::Struct {
 245     let predicates = cx.tcx.explicit_predicates_of(did);
 246     let variant = cx.tcx.adt_def(did).non_enum_variant();
 247
 248     clean::Struct {
 249         struct_type: variant.ctor_kind,
 250         generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
 251         fields: variant.fields.iter().map(|x| x.clean(cx)).collect(),
 252         fields_stripped: false,
 253     }
 254 }
 255
 256 fn build_union(cx: &mut DocContext<'_>, did: DefId) -> clean::Union {
 257     let predicates = cx.tcx.explicit_predicates_of(did);
 258     let variant = cx.tcx.adt_def(did).non_enum_variant();
 259
 260     let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
 261     let fields = variant.fields.iter().map(|x| x.clean(cx)).collect();
 262     clean::Union { generics, fields, fields_stripped: false }
 263 }
 264
 265 fn build_type_alias(cx: &mut DocContext<'_>, did: DefId) -> clean::Typedef {
 266     let predicates = cx.tcx.explicit_predicates_of(did);
 267     let type_ = cx.tcx.type_of(did).clean(cx);
 268
 269     clean::Typedef {
 270         type_,
 271         generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
 272         item_type: None,
 273     }
 274 }
 275
 276 /// Builds all inherent implementations of an ADT (struct/union/enum) or Trait item/path/reexport.
 277 crate fn build_impls(
 278     cx: &mut DocContext<'_>,
 279     parent_module: Option<DefId>,
 280     did: DefId,
 281     attrs: Option<Attrs<'_>>,
 282     ret: &mut Vec<clean::Item>,
 283 ) {
 284     let _prof_timer = cx.tcx.sess.prof.generic_activity("build_inherent_impls");
 285     let tcx = cx.tcx;
 286
 287     // for each implementation of an item represented by `did`, build the clean::Item for that impl
 288     for &did in tcx.inherent_impls(did).iter() {
 289         build_impl(cx, parent_module, did, attrs, ret);
 290     }
 291 }
 292
 293 /// `parent_module` refers to the parent of the re-export, not the original item
 294 fn merge_attrs(
 295     cx: &mut DocContext<'_>,
 296     parent_module: Option<DefId>,
 297     old_attrs: Attrs<'_>,
 298     new_attrs: Option<Attrs<'_>>,
 299 ) -> (clean::Attributes, Option<Arc<clean::cfg::Cfg>>) {
 300     // NOTE: If we have additional attributes (from a re-export),
 301     // always insert them first. This ensure that re-export
 302     // doc comments show up before the original doc comments
 303     // when we render them.
 304     if let Some(inner) = new_attrs {
 305         let mut both = inner.to_vec();
 306         both.extend_from_slice(old_attrs);
 307         (
 308             if let Some(new_id) = parent_module {
 309                 Attributes::from_ast(old_attrs, Some((inner, new_id)))
 310             } else {
 311                 Attributes::from_ast(&both, None)
 312             },
 313             both.cfg(cx.tcx, &cx.cache.hidden_cfg),
 314         )
 315     } else {
 316         (old_attrs.clean(cx), old_attrs.cfg(cx.tcx, &cx.cache.hidden_cfg))
 317     }
 318 }
 319
 320 /// Inline an `impl`, inherent or of a trait. The `did` must be for an `impl`.
 321 crate fn build_impl(
 322     cx: &mut DocContext<'_>,
 323     parent_module: Option<DefId>,
 324     did: DefId,
 325     attrs: Option<Attrs<'_>>,
 326     ret: &mut Vec<clean::Item>,
 327 ) {
 328     if !cx.inlined.insert(did.into()) {
 329         return;
 330     }
 331
 332     let _prof_timer = cx.tcx.sess.prof.generic_activity("build_impl");
 333
 334     let tcx = cx.tcx;
 335     let associated_trait = tcx.impl_trait_ref(did);
 336
 337     // Only inline impl if the implemented trait is
 338     // reachable in rustdoc generated documentation
 339     if !did.is_local() {
 340         if let Some(traitref) = associated_trait {
 341             let did = traitref.def_id;
 342             if !cx.cache.access_levels.is_public(did) {
 343                 return;
 344             }
 345
 346             if let Some(stab) = tcx.lookup_stability(did) {
 347                 if stab.level.is_unstable() && stab.feature == sym::rustc_private {
 348                     return;
 349                 }
 350             }
 351         }
 352     }
 353
 354     let impl_item = match did.as_local() {
 355         Some(did) => match &tcx.hir().expect_item(did).kind {
 356             hir::ItemKind::Impl(impl_) => Some(impl_),
 357             _ => panic!("`DefID` passed to `build_impl` is not an `impl"),
 358         },
 359         None => None,
 360     };
 361
 362     let for_ = match &impl_item {
 363         Some(impl_) => impl_.self_ty.clean(cx),
 364         None => tcx.type_of(did).clean(cx),
 365     };
 366
 367     // Only inline impl if the implementing type is
 368     // reachable in rustdoc generated documentation
 369     if !did.is_local() {
 370         if let Some(did) = for_.def_id(&cx.cache) {
 371             if !cx.cache.access_levels.is_public(did) {
 372                 return;
 373             }
 374
 375             if let Some(stab) = tcx.lookup_stability(did) {
 376                 if stab.level.is_unstable() && stab.feature == sym::rustc_private {
 377                     return;
 378                 }
 379             }
 380         }
 381     }
 382
 383     let document_hidden = cx.render_options.document_hidden;
 384     let predicates = tcx.explicit_predicates_of(did);
 385     let (trait_items, generics) = match impl_item {
 386         Some(impl_) => (
 387             impl_
 388                 .items
 389                 .iter()
 390                 .map(|item| tcx.hir().impl_item(item.id))
 391                 .filter(|item| {
 392                     // Filter out impl items whose corresponding trait item has `doc(hidden)`
 393                     // not to document such impl items.
 394                     // For inherent impls, we don't do any filtering, because that's already done in strip_hidden.rs.
 395
 396                     // When `--document-hidden-items` is passed, we don't
 397                     // do any filtering, too.
 398                     if document_hidden {
 399                         return true;
 400                     }
 401                     if let Some(associated_trait) = associated_trait {
 402                         let assoc_kind = match item.kind {
 403                             hir::ImplItemKind::Const(..) => ty::AssocKind::Const,
 404                             hir::ImplItemKind::Fn(..) => ty::AssocKind::Fn,
 405                             hir::ImplItemKind::TyAlias(..) => ty::AssocKind::Type,
 406                         };
 407                         let trait_item = tcx
 408                             .associated_items(associated_trait.def_id)
 409                             .find_by_name_and_kind(
 410                                 tcx,
 411                                 item.ident,
 412                                 assoc_kind,
 413                                 associated_trait.def_id,
 414                             )
 415                             .unwrap(); // SAFETY: For all impl items there exists trait item that has the same name.
 416                         !tcx.is_doc_hidden(trait_item.def_id)
 417                     } else {
 418                         true
 419                     }
 420                 })
 421                 .map(|item| item.clean(cx))
 422                 .collect::<Vec<_>>(),
 423             impl_.generics.clean(cx),
 424         ),
 425         None => (
 426             tcx.associated_items(did)
 427                 .in_definition_order()
 428                 .filter_map(|item| {
 429                     if associated_trait.is_some() || item.vis.is_public() {
 430                         Some(item.clean(cx))
 431                     } else {
 432                         None
 433                     }
 434                 })
 435                 .collect::<Vec<_>>(),
 436             clean::enter_impl_trait(cx, |cx| {
 437                 clean_ty_generics(cx, tcx.generics_of(did), predicates)
 438             }),
 439         ),
 440     };
 441     let polarity = tcx.impl_polarity(did);
 442     let trait_ = associated_trait.map(|t| t.clean(cx));
 443     if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
 444         super::build_deref_target_impls(cx, &trait_items, ret);
 445     }
 446
 447     // Return if the trait itself or any types of the generic parameters are doc(hidden).
 448     let mut stack: Vec<&Type> = vec![&for_];
 449
 450     if let Some(did) = trait_.as_ref().map(|t| t.def_id()) {
 451         if tcx.is_doc_hidden(did) {
 452             return;
 453         }
 454     }
 455     if let Some(generics) = trait_.as_ref().and_then(|t| t.generics()) {
 456         stack.extend(generics);
 457     }
 458
 459     while let Some(ty) = stack.pop() {
 460         if let Some(did) = ty.def_id(&cx.cache) {
 461             if tcx.is_doc_hidden(did) {
 462                 return;
 463             }
 464         }
 465         if let Some(generics) = ty.generics() {
 466             stack.extend(generics);
 467         }
 468     }
 469
 470     if let Some(did) = trait_.as_ref().map(|t| t.def_id()) {
 471         record_extern_trait(cx, did);
 472     }
 473
 474     let (merged_attrs, cfg) = merge_attrs(cx, parent_module, load_attrs(cx, did), attrs);
 475     trace!("merged_attrs={:?}", merged_attrs);
 476
 477     trace!(
 478         "build_impl: impl {:?} for {:?}",
 479         trait_.as_ref().map(|t| t.def_id()),
 480         for_.def_id(&cx.cache)
 481     );
 482     ret.push(clean::Item::from_def_id_and_attrs_and_parts(
 483         did,
 484         None,
 485         clean::ImplItem(clean::Impl {
 486             unsafety: hir::Unsafety::Normal,
 487             generics,
 488             trait_,
 489             for_,
 490             items: trait_items,
 491             polarity,
 492             kind: ImplKind::Normal,
 493         }),
 494         box merged_attrs,
 495         cx,
 496         cfg,
 497     ));
 498 }
 499
 500 fn build_module(
 501     cx: &mut DocContext<'_>,
 502     did: DefId,
 503     visited: &mut FxHashSet<DefId>,
 504 ) -> clean::Module {
 505     let mut items = Vec::new();
 506
 507     // If we're re-exporting a re-export it may actually re-export something in
 508     // two namespaces, so the target may be listed twice. Make sure we only
 509     // visit each node at most once.
 510     for &item in cx.tcx.module_children(did).iter() {
 511         if item.vis.is_public() {
 512             let res = item.res.expect_non_local();
 513             if let Some(def_id) = res.mod_def_id() {
 514                 if did == def_id || !visited.insert(def_id) {
 515                     continue;
 516                 }
 517             }
 518             if let Res::PrimTy(p) = res {
 519                 // Primitive types can't be inlined so generate an import instead.
 520                 let prim_ty = clean::PrimitiveType::from(p);
 521                 items.push(clean::Item {
 522                     name: None,
 523                     attrs: box clean::Attributes::default(),
 524                     def_id: ItemId::Primitive(prim_ty, did.krate),
 525                     visibility: clean::Public,
 526                     kind: box clean::ImportItem(clean::Import::new_simple(
 527                         item.ident.name,
 528                         clean::ImportSource {
 529                             path: clean::Path {
 530                                 res,
 531                                 segments: vec![clean::PathSegment {
 532                                     name: prim_ty.as_sym(),
 533                                     args: clean::GenericArgs::AngleBracketed {
 534                                         args: Vec::new(),
 535                                         bindings: ThinVec::new(),
 536                                     },
 537                                 }],
 538                             },
 539                             did: None,
 540                         },
 541                         true,
 542                     )),
 543                     cfg: None,
 544                 });
 545             } else if let Some(i) = try_inline(cx, did, None, res, item.ident.name, None, visited) {
 546                 items.extend(i)
 547             }
 548         }
 549     }
 550
 551     let span = clean::Span::new(cx.tcx.def_span(did));
 552     clean::Module { items, span }
 553 }
 554
 555 crate fn print_inlined_const(tcx: TyCtxt<'_>, did: DefId) -> String {
 556     if let Some(did) = did.as_local() {
 557         let hir_id = tcx.hir().local_def_id_to_hir_id(did);
 558         rustc_hir_pretty::id_to_string(&tcx.hir(), hir_id)
 559     } else {
 560         tcx.rendered_const(did).clone()
 561     }
 562 }
 563
 564 fn build_const(cx: &mut DocContext<'_>, def_id: DefId) -> clean::Constant {
 565     clean::Constant {
 566         type_: cx.tcx.type_of(def_id).clean(cx),
 567         kind: clean::ConstantKind::Extern { def_id },
 568     }
 569 }
 570
 571 fn build_static(cx: &mut DocContext<'_>, did: DefId, mutable: bool) -> clean::Static {
 572     clean::Static {
 573         type_: cx.tcx.type_of(did).clean(cx),
 574         mutability: if mutable { Mutability::Mut } else { Mutability::Not },
 575         expr: None,
 576     }
 577 }
 578
 579 fn build_macro(
 580     cx: &mut DocContext<'_>,
 581     def_id: DefId,
 582     name: Symbol,
 583     import_def_id: Option<DefId>,
 584 ) -> clean::ItemKind {
 585     match CStore::from_tcx(cx.tcx).load_macro_untracked(def_id, cx.sess()) {
 586         LoadedMacro::MacroDef(item_def, _) => {
 587             if let ast::ItemKind::MacroDef(ref def) = item_def.kind {
 588                 let vis = cx.tcx.visibility(import_def_id.unwrap_or(def_id)).clean(cx);
 589                 clean::MacroItem(clean::Macro {
 590                     source: utils::display_macro_source(cx, name, def, def_id, vis),
 591                 })
 592             } else {
 593                 unreachable!()
 594             }
 595         }
 596         LoadedMacro::ProcMacro(ext) => clean::ProcMacroItem(clean::ProcMacro {
 597             kind: ext.macro_kind(),
 598             helpers: ext.helper_attrs,
 599         }),
 600     }
 601 }
 602
 603 /// A trait's generics clause actually contains all of the predicates for all of
 604 /// its associated types as well. We specifically move these clauses to the
 605 /// associated types instead when displaying, so when we're generating the
 606 /// generics for the trait itself we need to be sure to remove them.
 607 /// We also need to remove the implied "recursive" Self: Trait bound.
 608 ///
 609 /// The inverse of this filtering logic can be found in the `Clean`
 610 /// implementation for `AssociatedType`
 611 fn filter_non_trait_generics(trait_did: DefId, mut g: clean::Generics) -> clean::Generics {
 612     for pred in &mut g.where_predicates {
 613         match *pred {
 614             clean::WherePredicate::BoundPredicate {
 615                 ty: clean::Generic(ref s),
 616                 ref mut bounds,
 617                 ..
 618             } if *s == kw::SelfUpper => {
 619                 bounds.retain(|bound| match bound {
 620                     clean::GenericBound::TraitBound(clean::PolyTrait { trait_, .. }, _) => {
 621                         trait_.def_id() != trait_did
 622                     }
 623                     _ => true,
 624                 });
 625             }
 626             _ => {}
 627         }
 628     }
 629
 630     g.where_predicates.retain(|pred| match pred {
 631         clean::WherePredicate::BoundPredicate {
 632             ty: clean::QPath { self_type: box clean::Generic(ref s), trait_, .. },
 633             bounds,
 634             ..
 635         } => !(bounds.is_empty() || *s == kw::SelfUpper && trait_.def_id() == trait_did),
 636         _ => true,
 637     });
 638     g
 639 }
 640
 641 /// Supertrait bounds for a trait are also listed in the generics coming from
 642 /// the metadata for a crate, so we want to separate those out and create a new
 643 /// list of explicit supertrait bounds to render nicely.
 644 fn separate_supertrait_bounds(
 645     mut g: clean::Generics,
 646 ) -> (clean::Generics, Vec<clean::GenericBound>) {
 647     let mut ty_bounds = Vec::new();
 648     g.where_predicates.retain(|pred| match *pred {
 649         clean::WherePredicate::BoundPredicate { ty: clean::Generic(ref s), ref bounds, .. }
 650             if *s == kw::SelfUpper =>
 651         {
 652             ty_bounds.extend(bounds.iter().cloned());
 653             false
 654         }
 655         _ => true,
 656     });
 657     (g, ty_bounds)
 658 }
 659
 660 crate fn record_extern_trait(cx: &mut DocContext<'_>, did: DefId) {
 661     if did.is_local() {
 662         return;
 663     }
 664
 665     {
 666         if cx.external_traits.borrow().contains_key(&did) || cx.active_extern_traits.contains(&did)
 667         {
 668             return;
 669         }
 670     }
 671
 672     {
 673         cx.active_extern_traits.insert(did);
 674     }
 675
 676     debug!("record_extern_trait: {:?}", did);
 677     let trait_ = build_external_trait(cx, did);
 678
 679     let trait_ = clean::TraitWithExtraInfo {
 680         trait_,
 681         is_notable: clean::utils::has_doc_flag(cx.tcx.get_attrs(did), sym::notable_trait),
 682     };
 683     cx.external_traits.borrow_mut().insert(did, trait_);
 684     cx.active_extern_traits.remove(&did);
 685 }