Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 727 insertions, 0 deletions

diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
new file mode 100644
index 000000000..58d0aedb0
--- /dev/null
+++ b/src/librustdoc/clean/inline.rs
@@ -0,0 +1,727 @@
+//! Support for inlining external documentation into the current AST.
+
+use std::iter::once;
+use std::sync::Arc;
+
+use rustc_ast as ast;
+use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::thin_vec::ThinVec;
+use rustc_hir as hir;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::def_id::DefId;
+use rustc_hir::Mutability;
+use rustc_metadata::creader::{CStore, LoadedMacro};
+use rustc_middle::ty::{self, TyCtxt};
+use rustc_span::hygiene::MacroKind;
+use rustc_span::symbol::{kw, sym, Symbol};
+
+use crate::clean::{
+    self, clean_fn_decl_from_did_and_sig, clean_middle_field, clean_middle_ty,
+    clean_trait_ref_with_bindings, clean_ty, clean_ty_generics, clean_variant_def,
+    clean_visibility, utils, Attributes, AttributesExt, Clean, ImplKind, ItemId, Type, Visibility,
+};
+use crate::core::DocContext;
+use crate::formats::item_type::ItemType;
+
+type Attrs<'hir> = &'hir [ast::Attribute];
+
+/// Attempt to inline a definition into this AST.
+///
+/// This function will fetch the definition specified, and if it is
+/// from another crate it will attempt to inline the documentation
+/// from the other crate into this crate.
+///
+/// This is primarily used for `pub use` statements which are, in general,
+/// implementation details. Inlining the documentation should help provide a
+/// better experience when reading the documentation in this use case.
+///
+/// The returned value is `None` if the definition could not be inlined,
+/// and `Some` of a vector of items if it was successfully expanded.
+///
+/// `parent_module` refers to the parent of the *re-export*, not the original item.
+pub(crate) fn try_inline(
+    cx: &mut DocContext<'_>,
+    parent_module: DefId,
+    import_def_id: Option<DefId>,
+    res: Res,
+    name: Symbol,
+    attrs: Option<Attrs<'_>>,
+    visited: &mut FxHashSet<DefId>,
+) -> Option<Vec<clean::Item>> {
+    let did = res.opt_def_id()?;
+    if did.is_local() {
+        return None;
+    }
+    let mut ret = Vec::new();
+
+    debug!("attrs={:?}", attrs);
+    let attrs_clone = attrs;
+
+    let kind = match res {
+        Res::Def(DefKind::Trait, did) => {
+            record_extern_fqn(cx, did, ItemType::Trait);
+            build_impls(cx, Some(parent_module), did, attrs, &mut ret);
+            clean::TraitItem(build_external_trait(cx, did))
+        }
+        Res::Def(DefKind::Fn, did) => {
+            record_extern_fqn(cx, did, ItemType::Function);
+            clean::FunctionItem(build_external_function(cx, did))
+        }
+        Res::Def(DefKind::Struct, did) => {
+            record_extern_fqn(cx, did, ItemType::Struct);
+            build_impls(cx, Some(parent_module), did, attrs, &mut ret);
+            clean::StructItem(build_struct(cx, did))
+        }
+        Res::Def(DefKind::Union, did) => {
+            record_extern_fqn(cx, did, ItemType::Union);
+            build_impls(cx, Some(parent_module), did, attrs, &mut ret);
+            clean::UnionItem(build_union(cx, did))
+        }
+        Res::Def(DefKind::TyAlias, did) => {
+            record_extern_fqn(cx, did, ItemType::Typedef);
+            build_impls(cx, Some(parent_module), did, attrs, &mut ret);
+            clean::TypedefItem(build_type_alias(cx, did))
+        }
+        Res::Def(DefKind::Enum, did) => {
+            record_extern_fqn(cx, did, ItemType::Enum);
+            build_impls(cx, Some(parent_module), did, attrs, &mut ret);
+            clean::EnumItem(build_enum(cx, did))
+        }
+        Res::Def(DefKind::ForeignTy, did) => {
+            record_extern_fqn(cx, did, ItemType::ForeignType);
+            build_impls(cx, Some(parent_module), did, attrs, &mut ret);
+            clean::ForeignTypeItem
+        }
+        // Never inline enum variants but leave them shown as re-exports.
+        Res::Def(DefKind::Variant, _) => return None,
+        // Assume that enum variants and struct types are re-exported next to
+        // their constructors.
+        Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) => return Some(Vec::new()),
+        Res::Def(DefKind::Mod, did) => {
+            record_extern_fqn(cx, did, ItemType::Module);
+            clean::ModuleItem(build_module(cx, did, visited))
+        }
+        Res::Def(DefKind::Static(_), did) => {
+            record_extern_fqn(cx, did, ItemType::Static);
+            clean::StaticItem(build_static(cx, did, cx.tcx.is_mutable_static(did)))
+        }
+        Res::Def(DefKind::Const, did) => {
+            record_extern_fqn(cx, did, ItemType::Constant);
+            clean::ConstantItem(build_const(cx, did))
+        }
+        Res::Def(DefKind::Macro(kind), did) => {
+            let mac = build_macro(cx, did, name, import_def_id);
+
+            let type_kind = match kind {
+                MacroKind::Bang => ItemType::Macro,
+                MacroKind::Attr => ItemType::ProcAttribute,
+                MacroKind::Derive => ItemType::ProcDerive,
+            };
+            record_extern_fqn(cx, did, type_kind);
+            mac
+        }
+        _ => return None,
+    };
+
+    let (attrs, cfg) = merge_attrs(cx, Some(parent_module), load_attrs(cx, did), attrs_clone);
+    cx.inlined.insert(did.into());
+    let mut item = clean::Item::from_def_id_and_attrs_and_parts(
+        did,
+        Some(name),
+        kind,
+        Box::new(attrs),
+        cx,
+        cfg,
+    );
+    if let Some(import_def_id) = import_def_id {
+        // The visibility needs to reflect the one from the reexport and not from the "source" DefId.
+        item.visibility = clean_visibility(cx.tcx.visibility(import_def_id));
+    }
+    ret.push(item);
+    Some(ret)
+}
+
+pub(crate) fn try_inline_glob(
+    cx: &mut DocContext<'_>,
+    res: Res,
+    visited: &mut FxHashSet<DefId>,
+    inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
+) -> Option<Vec<clean::Item>> {
+    let did = res.opt_def_id()?;
+    if did.is_local() {
+        return None;
+    }
+
+    match res {
+        Res::Def(DefKind::Mod, did) => {
+            let mut items = build_module_items(cx, did, visited, inlined_names);
+            items.drain_filter(|item| {
+                if let Some(name) = item.name {
+                    // If an item with the same type and name already exists,
+                    // it takes priority over the inlined stuff.
+                    !inlined_names.insert((item.type_(), name))
+                } else {
+                    false
+                }
+            });
+            Some(items)
+        }
+        // glob imports on things like enums aren't inlined even for local exports, so just bail
+        _ => None,
+    }
+}
+
+pub(crate) fn load_attrs<'hir>(cx: &DocContext<'hir>, did: DefId) -> Attrs<'hir> {
+    cx.tcx.get_attrs_unchecked(did)
+}
+
+/// Record an external fully qualified name in the external_paths cache.
+///
+/// These names are used later on by HTML rendering to generate things like
+/// source links back to the original item.
+pub(crate) fn record_extern_fqn(cx: &mut DocContext<'_>, did: DefId, kind: ItemType) {
+    let crate_name = cx.tcx.crate_name(did.krate);
+
+    let relative =
+        cx.tcx.def_path(did).data.into_iter().filter_map(|elem| elem.data.get_opt_name());
+    let fqn = if let ItemType::Macro = kind {
+        // Check to see if it is a macro 2.0 or built-in macro
+        if matches!(
+            CStore::from_tcx(cx.tcx).load_macro_untracked(did, cx.sess()),
+            LoadedMacro::MacroDef(def, _)
+                if matches!(&def.kind, ast::ItemKind::MacroDef(ast_def)
+                    if !ast_def.macro_rules)
+        ) {
+            once(crate_name).chain(relative).collect()
+        } else {
+            vec![crate_name, relative.last().expect("relative was empty")]
+        }
+    } else {
+        once(crate_name).chain(relative).collect()
+    };
+
+    if did.is_local() {
+        cx.cache.exact_paths.insert(did, fqn);
+    } else {
+        cx.cache.external_paths.insert(did, (fqn, kind));
+    }
+}
+
+pub(crate) fn build_external_trait(cx: &mut DocContext<'_>, did: DefId) -> clean::Trait {
+    let trait_items = cx
+        .tcx
+        .associated_items(did)
+        .in_definition_order()
+        .map(|item| {
+            // When building an external trait, the cleaned trait will have all items public,
+            // which causes methods to have a `pub` prefix, which is invalid since items in traits
+            // can not have a visibility prefix. Thus we override the visibility here manually.
+            // See https://github.com/rust-lang/rust/issues/81274
+            clean::Item { visibility: Visibility::Inherited, ..item.clean(cx) }
+        })
+        .collect();
+
+    let predicates = cx.tcx.predicates_of(did);
+    let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
+    let generics = filter_non_trait_generics(did, generics);
+    let (generics, supertrait_bounds) = separate_supertrait_bounds(generics);
+    clean::Trait { def_id: did, generics, items: trait_items, bounds: supertrait_bounds }
+}
+
+fn build_external_function<'tcx>(cx: &mut DocContext<'tcx>, did: DefId) -> Box<clean::Function> {
+    let sig = cx.tcx.fn_sig(did);
+
+    let predicates = cx.tcx.predicates_of(did);
+    let (generics, decl) = clean::enter_impl_trait(cx, |cx| {
+        // NOTE: generics need to be cleaned before the decl!
+        let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
+        let decl = clean_fn_decl_from_did_and_sig(cx, Some(did), sig);
+        (generics, decl)
+    });
+    Box::new(clean::Function { decl, generics })
+}
+
+fn build_enum(cx: &mut DocContext<'_>, did: DefId) -> clean::Enum {
+    let predicates = cx.tcx.explicit_predicates_of(did);
+
+    clean::Enum {
+        generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
+        variants: cx.tcx.adt_def(did).variants().iter().map(|v| clean_variant_def(v, cx)).collect(),
+    }
+}
+
+fn build_struct(cx: &mut DocContext<'_>, did: DefId) -> clean::Struct {
+    let predicates = cx.tcx.explicit_predicates_of(did);
+    let variant = cx.tcx.adt_def(did).non_enum_variant();
+
+    clean::Struct {
+        struct_type: variant.ctor_kind,
+        generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
+        fields: variant.fields.iter().map(|x| clean_middle_field(x, cx)).collect(),
+    }
+}
+
+fn build_union(cx: &mut DocContext<'_>, did: DefId) -> clean::Union {
+    let predicates = cx.tcx.explicit_predicates_of(did);
+    let variant = cx.tcx.adt_def(did).non_enum_variant();
+
+    let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
+    let fields = variant.fields.iter().map(|x| clean_middle_field(x, cx)).collect();
+    clean::Union { generics, fields }
+}
+
+fn build_type_alias(cx: &mut DocContext<'_>, did: DefId) -> Box<clean::Typedef> {
+    let predicates = cx.tcx.explicit_predicates_of(did);
+    let type_ = clean_middle_ty(cx.tcx.type_of(did), cx, Some(did));
+
+    Box::new(clean::Typedef {
+        type_,
+        generics: clean_ty_generics(cx, cx.tcx.generics_of(did), predicates),
+        item_type: None,
+    })
+}
+
+/// Builds all inherent implementations of an ADT (struct/union/enum) or Trait item/path/reexport.
+pub(crate) fn build_impls(
+    cx: &mut DocContext<'_>,
+    parent_module: Option<DefId>,
+    did: DefId,
+    attrs: Option<Attrs<'_>>,
+    ret: &mut Vec<clean::Item>,
+) {
+    let _prof_timer = cx.tcx.sess.prof.generic_activity("build_inherent_impls");
+    let tcx = cx.tcx;
+
+    // for each implementation of an item represented by `did`, build the clean::Item for that impl
+    for &did in tcx.inherent_impls(did).iter() {
+        build_impl(cx, parent_module, did, attrs, ret);
+    }
+}
+
+/// `parent_module` refers to the parent of the re-export, not the original item
+fn merge_attrs(
+    cx: &mut DocContext<'_>,
+    parent_module: Option<DefId>,
+    old_attrs: Attrs<'_>,
+    new_attrs: Option<Attrs<'_>>,
+) -> (clean::Attributes, Option<Arc<clean::cfg::Cfg>>) {
+    // NOTE: If we have additional attributes (from a re-export),
+    // always insert them first. This ensure that re-export
+    // doc comments show up before the original doc comments
+    // when we render them.
+    if let Some(inner) = new_attrs {
+        let mut both = inner.to_vec();
+        both.extend_from_slice(old_attrs);
+        (
+            if let Some(new_id) = parent_module {
+                Attributes::from_ast_with_additional(old_attrs, (inner, new_id))
+            } else {
+                Attributes::from_ast(&both)
+            },
+            both.cfg(cx.tcx, &cx.cache.hidden_cfg),
+        )
+    } else {
+        (Attributes::from_ast(&old_attrs), old_attrs.cfg(cx.tcx, &cx.cache.hidden_cfg))
+    }
+}
+
+/// Inline an `impl`, inherent or of a trait. The `did` must be for an `impl`.
+pub(crate) fn build_impl(
+    cx: &mut DocContext<'_>,
+    parent_module: Option<DefId>,
+    did: DefId,
+    attrs: Option<Attrs<'_>>,
+    ret: &mut Vec<clean::Item>,
+) {
+    if !cx.inlined.insert(did.into()) {
+        return;
+    }
+
+    let _prof_timer = cx.tcx.sess.prof.generic_activity("build_impl");
+
+    let tcx = cx.tcx;
+    let associated_trait = tcx.impl_trait_ref(did);
+
+    // Only inline impl if the implemented trait is
+    // reachable in rustdoc generated documentation
+    if !did.is_local() {
+        if let Some(traitref) = associated_trait {
+            let did = traitref.def_id;
+            if !cx.cache.access_levels.is_public(did) {
+                return;
+            }
+
+            if let Some(stab) = tcx.lookup_stability(did) {
+                if stab.is_unstable() && stab.feature == sym::rustc_private {
+                    return;
+                }
+            }
+        }
+    }
+
+    let impl_item = match did.as_local() {
+        Some(did) => match &tcx.hir().expect_item(did).kind {
+            hir::ItemKind::Impl(impl_) => Some(impl_),
+            _ => panic!("`DefID` passed to `build_impl` is not an `impl"),
+        },
+        None => None,
+    };
+
+    let for_ = match &impl_item {
+        Some(impl_) => clean_ty(impl_.self_ty, cx),
+        None => clean_middle_ty(tcx.type_of(did), cx, Some(did)),
+    };
+
+    // Only inline impl if the implementing type is
+    // reachable in rustdoc generated documentation
+    if !did.is_local() {
+        if let Some(did) = for_.def_id(&cx.cache) {
+            if !cx.cache.access_levels.is_public(did) {
+                return;
+            }
+
+            if let Some(stab) = tcx.lookup_stability(did) {
+                if stab.is_unstable() && stab.feature == sym::rustc_private {
+                    return;
+                }
+            }
+        }
+    }
+
+    let document_hidden = cx.render_options.document_hidden;
+    let predicates = tcx.explicit_predicates_of(did);
+    let (trait_items, generics) = match impl_item {
+        Some(impl_) => (
+            impl_
+                .items
+                .iter()
+                .map(|item| tcx.hir().impl_item(item.id))
+                .filter(|item| {
+                    // Filter out impl items whose corresponding trait item has `doc(hidden)`
+                    // not to document such impl items.
+                    // For inherent impls, we don't do any filtering, because that's already done in strip_hidden.rs.
+
+                    // When `--document-hidden-items` is passed, we don't
+                    // do any filtering, too.
+                    if document_hidden {
+                        return true;
+                    }
+                    if let Some(associated_trait) = associated_trait {
+                        let assoc_kind = match item.kind {
+                            hir::ImplItemKind::Const(..) => ty::AssocKind::Const,
+                            hir::ImplItemKind::Fn(..) => ty::AssocKind::Fn,
+                            hir::ImplItemKind::TyAlias(..) => ty::AssocKind::Type,
+                        };
+                        let trait_item = tcx
+                            .associated_items(associated_trait.def_id)
+                            .find_by_name_and_kind(
+                                tcx,
+                                item.ident,
+                                assoc_kind,
+                                associated_trait.def_id,
+                            )
+                            .unwrap(); // SAFETY: For all impl items there exists trait item that has the same name.
+                        !tcx.is_doc_hidden(trait_item.def_id)
+                    } else {
+                        true
+                    }
+                })
+                .map(|item| item.clean(cx))
+                .collect::<Vec<_>>(),
+            impl_.generics.clean(cx),
+        ),
+        None => (
+            tcx.associated_items(did)
+                .in_definition_order()
+                .filter(|item| {
+                    // If this is a trait impl, filter out associated items whose corresponding item
+                    // in the associated trait is marked `doc(hidden)`.
+                    // If this is an inherent impl, filter out private associated items.
+                    if let Some(associated_trait) = associated_trait {
+                        let trait_item = tcx
+                            .associated_items(associated_trait.def_id)
+                            .find_by_name_and_kind(
+                                tcx,
+                                item.ident(tcx),
+                                item.kind,
+                                associated_trait.def_id,
+                            )
+                            .unwrap(); // corresponding associated item has to exist
+                        !tcx.is_doc_hidden(trait_item.def_id)
+                    } else {
+                        item.visibility(tcx).is_public()
+                    }
+                })
+                .map(|item| item.clean(cx))
+                .collect::<Vec<_>>(),
+            clean::enter_impl_trait(cx, |cx| {
+                clean_ty_generics(cx, tcx.generics_of(did), predicates)
+            }),
+        ),
+    };
+    let polarity = tcx.impl_polarity(did);
+    let trait_ = associated_trait.map(|t| clean_trait_ref_with_bindings(cx, t, &[]));
+    if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
+        super::build_deref_target_impls(cx, &trait_items, ret);
+    }
+
+    // Return if the trait itself or any types of the generic parameters are doc(hidden).
+    let mut stack: Vec<&Type> = vec![&for_];
+
+    if let Some(did) = trait_.as_ref().map(|t| t.def_id()) {
+        if tcx.is_doc_hidden(did) {
+            return;
+        }
+    }
+    if let Some(generics) = trait_.as_ref().and_then(|t| t.generics()) {
+        stack.extend(generics);
+    }
+
+    while let Some(ty) = stack.pop() {
+        if let Some(did) = ty.def_id(&cx.cache) {
+            if tcx.is_doc_hidden(did) {
+                return;
+            }
+        }
+        if let Some(generics) = ty.generics() {
+            stack.extend(generics);
+        }
+    }
+
+    if let Some(did) = trait_.as_ref().map(|t| t.def_id()) {
+        record_extern_trait(cx, did);
+    }
+
+    let (merged_attrs, cfg) = merge_attrs(cx, parent_module, load_attrs(cx, did), attrs);
+    trace!("merged_attrs={:?}", merged_attrs);
+
+    trace!(
+        "build_impl: impl {:?} for {:?}",
+        trait_.as_ref().map(|t| t.def_id()),
+        for_.def_id(&cx.cache)
+    );
+    ret.push(clean::Item::from_def_id_and_attrs_and_parts(
+        did,
+        None,
+        clean::ImplItem(Box::new(clean::Impl {
+            unsafety: hir::Unsafety::Normal,
+            generics,
+            trait_,
+            for_,
+            items: trait_items,
+            polarity,
+            kind: if utils::has_doc_flag(tcx, did, sym::fake_variadic) {
+                ImplKind::FakeVaradic
+            } else {
+                ImplKind::Normal
+            },
+        })),
+        Box::new(merged_attrs),
+        cx,
+        cfg,
+    ));
+}
+
+fn build_module(
+    cx: &mut DocContext<'_>,
+    did: DefId,
+    visited: &mut FxHashSet<DefId>,
+) -> clean::Module {
+    let items = build_module_items(cx, did, visited, &mut FxHashSet::default());
+
+    let span = clean::Span::new(cx.tcx.def_span(did));
+    clean::Module { items, span }
+}
+
+fn build_module_items(
+    cx: &mut DocContext<'_>,
+    did: DefId,
+    visited: &mut FxHashSet<DefId>,
+    inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
+) -> Vec<clean::Item> {
+    let mut items = Vec::new();
+
+    // If we're re-exporting a re-export it may actually re-export something in
+    // two namespaces, so the target may be listed twice. Make sure we only
+    // visit each node at most once.
+    for &item in cx.tcx.module_children(did).iter() {
+        if item.vis.is_public() {
+            let res = item.res.expect_non_local();
+            if let Some(def_id) = res.mod_def_id() {
+                // If we're inlining a glob import, it's possible to have
+                // two distinct modules with the same name. We don't want to
+                // inline it, or mark any of its contents as visited.
+                if did == def_id
+                    || inlined_names.contains(&(ItemType::Module, item.ident.name))
+                    || !visited.insert(def_id)
+                {
+                    continue;
+                }
+            }
+            if let Res::PrimTy(p) = res {
+                // Primitive types can't be inlined so generate an import instead.
+                let prim_ty = clean::PrimitiveType::from(p);
+                items.push(clean::Item {
+                    name: None,
+                    attrs: Box::new(clean::Attributes::default()),
+                    item_id: ItemId::Primitive(prim_ty, did.krate),
+                    visibility: clean::Public,
+                    kind: Box::new(clean::ImportItem(clean::Import::new_simple(
+                        item.ident.name,
+                        clean::ImportSource {
+                            path: clean::Path {
+                                res,
+                                segments: vec![clean::PathSegment {
+                                    name: prim_ty.as_sym(),
+                                    args: clean::GenericArgs::AngleBracketed {
+                                        args: Default::default(),
+                                        bindings: ThinVec::new(),
+                                    },
+                                }],
+                            },
+                            did: None,
+                        },
+                        true,
+                    ))),
+                    cfg: None,
+                });
+            } else if let Some(i) = try_inline(cx, did, None, res, item.ident.name, None, visited) {
+                items.extend(i)
+            }
+        }
+    }
+
+    items
+}
+
+pub(crate) fn print_inlined_const(tcx: TyCtxt<'_>, did: DefId) -> String {
+    if let Some(did) = did.as_local() {
+        let hir_id = tcx.hir().local_def_id_to_hir_id(did);
+        rustc_hir_pretty::id_to_string(&tcx.hir(), hir_id)
+    } else {
+        tcx.rendered_const(did).clone()
+    }
+}
+
+fn build_const(cx: &mut DocContext<'_>, def_id: DefId) -> clean::Constant {
+    clean::Constant {
+        type_: clean_middle_ty(cx.tcx.type_of(def_id), cx, Some(def_id)),
+        kind: clean::ConstantKind::Extern { def_id },
+    }
+}
+
+fn build_static(cx: &mut DocContext<'_>, did: DefId, mutable: bool) -> clean::Static {
+    clean::Static {
+        type_: clean_middle_ty(cx.tcx.type_of(did), cx, Some(did)),
+        mutability: if mutable { Mutability::Mut } else { Mutability::Not },
+        expr: None,
+    }
+}
+
+fn build_macro(
+    cx: &mut DocContext<'_>,
+    def_id: DefId,
+    name: Symbol,
+    import_def_id: Option<DefId>,
+) -> clean::ItemKind {
+    match CStore::from_tcx(cx.tcx).load_macro_untracked(def_id, cx.sess()) {
+        LoadedMacro::MacroDef(item_def, _) => {
+            if let ast::ItemKind::MacroDef(ref def) = item_def.kind {
+                let vis = clean_visibility(cx.tcx.visibility(import_def_id.unwrap_or(def_id)));
+                clean::MacroItem(clean::Macro {
+                    source: utils::display_macro_source(cx, name, def, def_id, vis),
+                })
+            } else {
+                unreachable!()
+            }
+        }
+        LoadedMacro::ProcMacro(ext) => clean::ProcMacroItem(clean::ProcMacro {
+            kind: ext.macro_kind(),
+            helpers: ext.helper_attrs,
+        }),
+    }
+}
+
+/// A trait's generics clause actually contains all of the predicates for all of
+/// its associated types as well. We specifically move these clauses to the
+/// associated types instead when displaying, so when we're generating the
+/// generics for the trait itself we need to be sure to remove them.
+/// We also need to remove the implied "recursive" Self: Trait bound.
+///
+/// The inverse of this filtering logic can be found in the `Clean`
+/// implementation for `AssociatedType`
+fn filter_non_trait_generics(trait_did: DefId, mut g: clean::Generics) -> clean::Generics {
+    for pred in &mut g.where_predicates {
+        match *pred {
+            clean::WherePredicate::BoundPredicate {
+                ty: clean::Generic(ref s),
+                ref mut bounds,
+                ..
+            } if *s == kw::SelfUpper => {
+                bounds.retain(|bound| match bound {
+                    clean::GenericBound::TraitBound(clean::PolyTrait { trait_, .. }, _) => {
+                        trait_.def_id() != trait_did
+                    }
+                    _ => true,
+                });
+            }
+            _ => {}
+        }
+    }
+
+    g.where_predicates.retain(|pred| match pred {
+        clean::WherePredicate::BoundPredicate {
+            ty: clean::QPath { self_type: box clean::Generic(ref s), trait_, .. },
+            bounds,
+            ..
+        } => !(bounds.is_empty() || *s == kw::SelfUpper && trait_.def_id() == trait_did),
+        _ => true,
+    });
+    g
+}
+
+/// Supertrait bounds for a trait are also listed in the generics coming from
+/// the metadata for a crate, so we want to separate those out and create a new
+/// list of explicit supertrait bounds to render nicely.
+fn separate_supertrait_bounds(
+    mut g: clean::Generics,
+) -> (clean::Generics, Vec<clean::GenericBound>) {
+    let mut ty_bounds = Vec::new();
+    g.where_predicates.retain(|pred| match *pred {
+        clean::WherePredicate::BoundPredicate { ty: clean::Generic(ref s), ref bounds, .. }
+            if *s == kw::SelfUpper =>
+        {
+            ty_bounds.extend(bounds.iter().cloned());
+            false
+        }
+        _ => true,
+    });
+    (g, ty_bounds)
+}
+
+pub(crate) fn record_extern_trait(cx: &mut DocContext<'_>, did: DefId) {
+    if did.is_local() {
+        return;
+    }
+
+    {
+        if cx.external_traits.borrow().contains_key(&did) || cx.active_extern_traits.contains(&did)
+        {
+            return;
+        }
+    }
+
+    {
+        cx.active_extern_traits.insert(did);
+    }
+
+    debug!("record_extern_trait: {:?}", did);
+    let trait_ = build_external_trait(cx, did);
+
+    let trait_ = clean::TraitWithExtraInfo {
+        trait_,
+        is_notable: clean::utils::has_doc_flag(cx.tcx, did, sym::notable_trait),
+    };
+    cx.external_traits.borrow_mut().insert(did, trait_);
+    cx.active_extern_traits.remove(&did);
+}