rustdoc/clean/
mod.rs

1//! This module defines the primary IR[^1] used in rustdoc together with the procedures that
2//! transform rustc data types into it.
3//!
4//! This IR — commonly referred to as the *cleaned AST* — is modeled after the [AST][ast].
5//!
6//! There are two kinds of transformation — *cleaning* — procedures:
7//!
8//! 1. Cleans [HIR][hir] types. Used for user-written code and inlined local re-exports
9//!    both found in the local crate.
10//! 2. Cleans [`rustc_middle::ty`] types. Used for inlined cross-crate re-exports and anything
11//!    output by the trait solver (e.g., when synthesizing blanket and auto-trait impls).
12//!    They usually have `ty` or `middle` in their name.
13//!
14//! Their name is prefixed by `clean_`.
15//!
16//! Both the HIR and the `rustc_middle::ty` IR are quite removed from the source code.
17//! The cleaned AST on the other hand is closer to it which simplifies the rendering process.
18//! Furthermore, operating on a single IR instead of two avoids duplicating efforts down the line.
19//!
20//! This IR is consumed by both the HTML and the JSON backend.
21//!
22//! [^1]: Intermediate representation.
23
24mod auto_trait;
25mod blanket_impl;
26pub(crate) mod cfg;
27pub(crate) mod inline;
28mod render_macro_matchers;
29mod simplify;
30pub(crate) mod types;
31pub(crate) mod utils;
32
33use std::borrow::Cow;
34use std::collections::BTreeMap;
35use std::mem;
36
37use rustc_ast::token::{Token, TokenKind};
38use rustc_ast::tokenstream::{TokenStream, TokenTree};
39use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet, IndexEntry};
40use rustc_errors::codes::*;
41use rustc_errors::{FatalError, struct_span_code_err};
42use rustc_hir::attrs::AttributeKind;
43use rustc_hir::def::{CtorKind, DefKind, MacroKinds, Res};
44use rustc_hir::def_id::{DefId, DefIdMap, DefIdSet, LOCAL_CRATE, LocalDefId};
45use rustc_hir::{LangItem, PredicateOrigin, find_attr};
46use rustc_hir_analysis::hir_ty_lowering::FeedConstTy;
47use rustc_hir_analysis::{lower_const_arg_for_rustdoc, lower_ty};
48use rustc_middle::metadata::Reexport;
49use rustc_middle::middle::resolve_bound_vars as rbv;
50use rustc_middle::ty::{self, AdtKind, GenericArgsRef, Ty, TyCtxt, TypeVisitableExt, TypingMode};
51use rustc_middle::{bug, span_bug};
52use rustc_span::ExpnKind;
53use rustc_span::hygiene::{AstPass, MacroKind};
54use rustc_span::symbol::{Ident, Symbol, kw, sym};
55use rustc_trait_selection::traits::wf::object_region_bounds;
56use thin_vec::ThinVec;
57use tracing::{debug, instrument};
58use utils::*;
59use {rustc_ast as ast, rustc_hir as hir};
60
61pub(crate) use self::types::*;
62pub(crate) use self::utils::{krate, register_res, synthesize_auto_trait_and_blanket_impls};
63use crate::core::DocContext;
64use crate::formats::item_type::ItemType;
65use crate::visit_ast::Module as DocModule;
66
67pub(crate) fn clean_doc_module<'tcx>(doc: &DocModule<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
68    let mut items: Vec<Item> = vec![];
69    let mut inserted = FxHashSet::default();
70    items.extend(doc.foreigns.iter().map(|(item, renamed, import_id)| {
71        let item = clean_maybe_renamed_foreign_item(cx, item, *renamed, *import_id);
72        if let Some(name) = item.name
73            && (cx.render_options.document_hidden || !item.is_doc_hidden())
74        {
75            inserted.insert((item.type_(), name));
76        }
77        item
78    }));
79    items.extend(doc.mods.iter().filter_map(|x| {
80        if !inserted.insert((ItemType::Module, x.name)) {
81            return None;
82        }
83        let item = clean_doc_module(x, cx);
84        if !cx.render_options.document_hidden && item.is_doc_hidden() {
85            // Hidden modules are stripped at a later stage.
86            // If a hidden module has the same name as a visible one, we want
87            // to keep both of them around.
88            inserted.remove(&(ItemType::Module, x.name));
89        }
90        Some(item)
91    }));
92
93    // Split up glob imports from all other items.
94    //
95    // This covers the case where somebody does an import which should pull in an item,
96    // but there's already an item with the same namespace and same name. Rust gives
97    // priority to the not-imported one, so we should, too.
98    items.extend(doc.items.values().flat_map(|(item, renamed, import_ids)| {
99        // First, lower everything other than glob imports.
100        if matches!(item.kind, hir::ItemKind::Use(_, hir::UseKind::Glob)) {
101            return Vec::new();
102        }
103        let v = clean_maybe_renamed_item(cx, item, *renamed, import_ids);
104        for item in &v {
105            if let Some(name) = item.name
106                && (cx.render_options.document_hidden || !item.is_doc_hidden())
107            {
108                inserted.insert((item.type_(), name));
109            }
110        }
111        v
112    }));
113    items.extend(doc.inlined_foreigns.iter().flat_map(|((_, renamed), (res, local_import_id))| {
114        let Some(def_id) = res.opt_def_id() else { return Vec::new() };
115        let name = renamed.unwrap_or_else(|| cx.tcx.item_name(def_id));
116        let import = cx.tcx.hir_expect_item(*local_import_id);
117        match import.kind {
118            hir::ItemKind::Use(path, kind) => {
119                let hir::UsePath { segments, span, .. } = *path;
120                let path = hir::Path { segments, res: *res, span };
121                clean_use_statement_inner(
122                    import,
123                    Some(name),
124                    &path,
125                    kind,
126                    cx,
127                    &mut Default::default(),
128                )
129            }
130            _ => unreachable!(),
131        }
132    }));
133    items.extend(doc.items.values().flat_map(|(item, renamed, _)| {
134        // Now we actually lower the imports, skipping everything else.
135        if let hir::ItemKind::Use(path, hir::UseKind::Glob) = item.kind {
136            clean_use_statement(item, *renamed, path, hir::UseKind::Glob, cx, &mut inserted)
137        } else {
138            // skip everything else
139            Vec::new()
140        }
141    }));
142
143    // determine if we should display the inner contents or
144    // the outer `mod` item for the source code.
145
146    let span = Span::new({
147        let where_outer = doc.where_outer(cx.tcx);
148        let sm = cx.sess().source_map();
149        let outer = sm.lookup_char_pos(where_outer.lo());
150        let inner = sm.lookup_char_pos(doc.where_inner.lo());
151        if outer.file.start_pos == inner.file.start_pos {
152            // mod foo { ... }
153            where_outer
154        } else {
155            // mod foo; (and a separate SourceFile for the contents)
156            doc.where_inner
157        }
158    });
159
160    let kind = ModuleItem(Module { items, span });
161    generate_item_with_correct_attrs(
162        cx,
163        kind,
164        doc.def_id.to_def_id(),
165        doc.name,
166        doc.import_id.as_slice(),
167        doc.renamed,
168    )
169}
170
171fn is_glob_import(tcx: TyCtxt<'_>, import_id: LocalDefId) -> bool {
172    if let hir::Node::Item(item) = tcx.hir_node_by_def_id(import_id)
173        && let hir::ItemKind::Use(_, use_kind) = item.kind
174    {
175        use_kind == hir::UseKind::Glob
176    } else {
177        false
178    }
179}
180
181fn generate_item_with_correct_attrs(
182    cx: &mut DocContext<'_>,
183    kind: ItemKind,
184    def_id: DefId,
185    name: Symbol,
186    import_ids: &[LocalDefId],
187    renamed: Option<Symbol>,
188) -> Item {
189    let target_attrs = inline::load_attrs(cx, def_id);
190    let attrs = if !import_ids.is_empty() {
191        let mut attrs = Vec::with_capacity(import_ids.len());
192        let mut is_inline = false;
193
194        for import_id in import_ids.iter().copied() {
195            // glob reexports are treated the same as `#[doc(inline)]` items.
196            //
197            // For glob re-exports the item may or may not exist to be re-exported (potentially the
198            // cfgs on the path up until the glob can be removed, and only cfgs on the globbed item
199            // itself matter), for non-inlined re-exports see #85043.
200            let import_is_inline =
201                hir_attr_lists(inline::load_attrs(cx, import_id.to_def_id()), sym::doc)
202                    .get_word_attr(sym::inline)
203                    .is_some()
204                    || (is_glob_import(cx.tcx, import_id)
205                        && (cx.render_options.document_hidden || !cx.tcx.is_doc_hidden(def_id)));
206            attrs.extend(get_all_import_attributes(cx, import_id, def_id, is_inline));
207            is_inline = is_inline || import_is_inline;
208        }
209        add_without_unwanted_attributes(&mut attrs, target_attrs, is_inline, None);
210        attrs
211    } else {
212        // We only keep the item's attributes.
213        target_attrs.iter().map(|attr| (Cow::Borrowed(attr), None)).collect()
214    };
215    let cfg = extract_cfg_from_attrs(
216        attrs.iter().map(move |(attr, _)| match attr {
217            Cow::Borrowed(attr) => *attr,
218            Cow::Owned(attr) => attr,
219        }),
220        cx.tcx,
221        &cx.cache.hidden_cfg,
222    );
223    let attrs = Attributes::from_hir_iter(attrs.iter().map(|(attr, did)| (&**attr, *did)), false);
224
225    let name = renamed.or(Some(name));
226    let mut item = Item::from_def_id_and_attrs_and_parts(def_id, name, kind, attrs, cfg);
227    // FIXME (GuillaumeGomez): Should we also make `inline_stmt_id` a `Vec` instead of an `Option`?
228    item.inner.inline_stmt_id = import_ids.first().copied();
229    item
230}
231
232fn clean_generic_bound<'tcx>(
233    bound: &hir::GenericBound<'tcx>,
234    cx: &mut DocContext<'tcx>,
235) -> Option<GenericBound> {
236    Some(match bound {
237        hir::GenericBound::Outlives(lt) => GenericBound::Outlives(clean_lifetime(lt, cx)),
238        hir::GenericBound::Trait(t) => {
239            // `T: [const] Destruct` is hidden because `T: Destruct` is a no-op.
240            if let hir::BoundConstness::Maybe(_) = t.modifiers.constness
241                && cx.tcx.lang_items().destruct_trait() == Some(t.trait_ref.trait_def_id().unwrap())
242            {
243                return None;
244            }
245
246            GenericBound::TraitBound(clean_poly_trait_ref(t, cx), t.modifiers)
247        }
248        hir::GenericBound::Use(args, ..) => {
249            GenericBound::Use(args.iter().map(|arg| clean_precise_capturing_arg(arg, cx)).collect())
250        }
251    })
252}
253
254pub(crate) fn clean_trait_ref_with_constraints<'tcx>(
255    cx: &mut DocContext<'tcx>,
256    trait_ref: ty::PolyTraitRef<'tcx>,
257    constraints: ThinVec<AssocItemConstraint>,
258) -> Path {
259    let kind = cx.tcx.def_kind(trait_ref.def_id()).into();
260    if !matches!(kind, ItemType::Trait | ItemType::TraitAlias) {
261        span_bug!(cx.tcx.def_span(trait_ref.def_id()), "`TraitRef` had unexpected kind {kind:?}");
262    }
263    inline::record_extern_fqn(cx, trait_ref.def_id(), kind);
264    let path = clean_middle_path(
265        cx,
266        trait_ref.def_id(),
267        true,
268        constraints,
269        trait_ref.map_bound(|tr| tr.args),
270    );
271
272    debug!(?trait_ref);
273
274    path
275}
276
277fn clean_poly_trait_ref_with_constraints<'tcx>(
278    cx: &mut DocContext<'tcx>,
279    poly_trait_ref: ty::PolyTraitRef<'tcx>,
280    constraints: ThinVec<AssocItemConstraint>,
281) -> GenericBound {
282    GenericBound::TraitBound(
283        PolyTrait {
284            trait_: clean_trait_ref_with_constraints(cx, poly_trait_ref, constraints),
285            generic_params: clean_bound_vars(poly_trait_ref.bound_vars(), cx),
286        },
287        hir::TraitBoundModifiers::NONE,
288    )
289}
290
291fn clean_lifetime(lifetime: &hir::Lifetime, cx: &DocContext<'_>) -> Lifetime {
292    if let Some(
293        rbv::ResolvedArg::EarlyBound(did)
294        | rbv::ResolvedArg::LateBound(_, _, did)
295        | rbv::ResolvedArg::Free(_, did),
296    ) = cx.tcx.named_bound_var(lifetime.hir_id)
297        && let Some(lt) = cx.args.get(&did.to_def_id()).and_then(|arg| arg.as_lt())
298    {
299        return *lt;
300    }
301    Lifetime(lifetime.ident.name)
302}
303
304pub(crate) fn clean_precise_capturing_arg(
305    arg: &hir::PreciseCapturingArg<'_>,
306    cx: &DocContext<'_>,
307) -> PreciseCapturingArg {
308    match arg {
309        hir::PreciseCapturingArg::Lifetime(lt) => {
310            PreciseCapturingArg::Lifetime(clean_lifetime(lt, cx))
311        }
312        hir::PreciseCapturingArg::Param(param) => PreciseCapturingArg::Param(param.ident.name),
313    }
314}
315
316pub(crate) fn clean_const<'tcx>(
317    constant: &hir::ConstArg<'tcx>,
318    _cx: &mut DocContext<'tcx>,
319) -> ConstantKind {
320    match &constant.kind {
321        hir::ConstArgKind::Path(qpath) => {
322            ConstantKind::Path { path: qpath_to_string(qpath).into() }
323        }
324        hir::ConstArgKind::Anon(anon) => ConstantKind::Anonymous { body: anon.body },
325        hir::ConstArgKind::Infer(..) => ConstantKind::Infer,
326    }
327}
328
329pub(crate) fn clean_middle_const<'tcx>(
330    constant: ty::Binder<'tcx, ty::Const<'tcx>>,
331    _cx: &mut DocContext<'tcx>,
332) -> ConstantKind {
333    // FIXME: instead of storing the stringified expression, store `self` directly instead.
334    ConstantKind::TyConst { expr: constant.skip_binder().to_string().into() }
335}
336
337pub(crate) fn clean_middle_region<'tcx>(
338    region: ty::Region<'tcx>,
339    cx: &mut DocContext<'tcx>,
340) -> Option<Lifetime> {
341    region.get_name(cx.tcx).map(Lifetime)
342}
343
344fn clean_where_predicate<'tcx>(
345    predicate: &hir::WherePredicate<'tcx>,
346    cx: &mut DocContext<'tcx>,
347) -> Option<WherePredicate> {
348    if !predicate.kind.in_where_clause() {
349        return None;
350    }
351    Some(match predicate.kind {
352        hir::WherePredicateKind::BoundPredicate(wbp) => {
353            let bound_params = wbp
354                .bound_generic_params
355                .iter()
356                .map(|param| clean_generic_param(cx, None, param))
357                .collect();
358            WherePredicate::BoundPredicate {
359                ty: clean_ty(wbp.bounded_ty, cx),
360                bounds: wbp.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
361                bound_params,
362            }
363        }
364
365        hir::WherePredicateKind::RegionPredicate(wrp) => WherePredicate::RegionPredicate {
366            lifetime: clean_lifetime(wrp.lifetime, cx),
367            bounds: wrp.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
368        },
369
370        // We should never actually reach this case because these predicates should've already been
371        // rejected in an earlier compiler pass. This feature isn't fully implemented (#20041).
372        hir::WherePredicateKind::EqPredicate(_) => bug!("EqPredicate"),
373    })
374}
375
376pub(crate) fn clean_predicate<'tcx>(
377    predicate: ty::Clause<'tcx>,
378    cx: &mut DocContext<'tcx>,
379) -> Option<WherePredicate> {
380    let bound_predicate = predicate.kind();
381    match bound_predicate.skip_binder() {
382        ty::ClauseKind::Trait(pred) => clean_poly_trait_predicate(bound_predicate.rebind(pred), cx),
383        ty::ClauseKind::RegionOutlives(pred) => Some(clean_region_outlives_predicate(pred, cx)),
384        ty::ClauseKind::TypeOutlives(pred) => {
385            Some(clean_type_outlives_predicate(bound_predicate.rebind(pred), cx))
386        }
387        ty::ClauseKind::Projection(pred) => {
388            Some(clean_projection_predicate(bound_predicate.rebind(pred), cx))
389        }
390        // FIXME(generic_const_exprs): should this do something?
391        ty::ClauseKind::ConstEvaluatable(..)
392        | ty::ClauseKind::WellFormed(..)
393        | ty::ClauseKind::ConstArgHasType(..)
394        | ty::ClauseKind::UnstableFeature(..)
395        // FIXME(const_trait_impl): We can probably use this `HostEffect` pred to render `~const`.
396        | ty::ClauseKind::HostEffect(_) => None,
397    }
398}
399
400fn clean_poly_trait_predicate<'tcx>(
401    pred: ty::PolyTraitPredicate<'tcx>,
402    cx: &mut DocContext<'tcx>,
403) -> Option<WherePredicate> {
404    // `T: [const] Destruct` is hidden because `T: Destruct` is a no-op.
405    // FIXME(const_trait_impl) check constness
406    if Some(pred.skip_binder().def_id()) == cx.tcx.lang_items().destruct_trait() {
407        return None;
408    }
409
410    let poly_trait_ref = pred.map_bound(|pred| pred.trait_ref);
411    Some(WherePredicate::BoundPredicate {
412        ty: clean_middle_ty(poly_trait_ref.self_ty(), cx, None, None),
413        bounds: vec![clean_poly_trait_ref_with_constraints(cx, poly_trait_ref, ThinVec::new())],
414        bound_params: Vec::new(),
415    })
416}
417
418fn clean_region_outlives_predicate<'tcx>(
419    pred: ty::RegionOutlivesPredicate<'tcx>,
420    cx: &mut DocContext<'tcx>,
421) -> WherePredicate {
422    let ty::OutlivesPredicate(a, b) = pred;
423
424    WherePredicate::RegionPredicate {
425        lifetime: clean_middle_region(a, cx).expect("failed to clean lifetime"),
426        bounds: vec![GenericBound::Outlives(
427            clean_middle_region(b, cx).expect("failed to clean bounds"),
428        )],
429    }
430}
431
432fn clean_type_outlives_predicate<'tcx>(
433    pred: ty::Binder<'tcx, ty::TypeOutlivesPredicate<'tcx>>,
434    cx: &mut DocContext<'tcx>,
435) -> WherePredicate {
436    let ty::OutlivesPredicate(ty, lt) = pred.skip_binder();
437
438    WherePredicate::BoundPredicate {
439        ty: clean_middle_ty(pred.rebind(ty), cx, None, None),
440        bounds: vec![GenericBound::Outlives(
441            clean_middle_region(lt, cx).expect("failed to clean lifetimes"),
442        )],
443        bound_params: Vec::new(),
444    }
445}
446
447fn clean_middle_term<'tcx>(
448    term: ty::Binder<'tcx, ty::Term<'tcx>>,
449    cx: &mut DocContext<'tcx>,
450) -> Term {
451    match term.skip_binder().kind() {
452        ty::TermKind::Ty(ty) => Term::Type(clean_middle_ty(term.rebind(ty), cx, None, None)),
453        ty::TermKind::Const(c) => Term::Constant(clean_middle_const(term.rebind(c), cx)),
454    }
455}
456
457fn clean_hir_term<'tcx>(term: &hir::Term<'tcx>, cx: &mut DocContext<'tcx>) -> Term {
458    match term {
459        hir::Term::Ty(ty) => Term::Type(clean_ty(ty, cx)),
460        hir::Term::Const(c) => {
461            let ct = lower_const_arg_for_rustdoc(cx.tcx, c, FeedConstTy::No);
462            Term::Constant(clean_middle_const(ty::Binder::dummy(ct), cx))
463        }
464    }
465}
466
467fn clean_projection_predicate<'tcx>(
468    pred: ty::Binder<'tcx, ty::ProjectionPredicate<'tcx>>,
469    cx: &mut DocContext<'tcx>,
470) -> WherePredicate {
471    WherePredicate::EqPredicate {
472        lhs: clean_projection(pred.map_bound(|p| p.projection_term), cx, None),
473        rhs: clean_middle_term(pred.map_bound(|p| p.term), cx),
474    }
475}
476
477fn clean_projection<'tcx>(
478    proj: ty::Binder<'tcx, ty::AliasTerm<'tcx>>,
479    cx: &mut DocContext<'tcx>,
480    parent_def_id: Option<DefId>,
481) -> QPathData {
482    let trait_ = clean_trait_ref_with_constraints(
483        cx,
484        proj.map_bound(|proj| proj.trait_ref(cx.tcx)),
485        ThinVec::new(),
486    );
487    let self_type = clean_middle_ty(proj.map_bound(|proj| proj.self_ty()), cx, None, None);
488    let self_def_id = match parent_def_id {
489        Some(parent_def_id) => cx.tcx.opt_parent(parent_def_id).or(Some(parent_def_id)),
490        None => self_type.def_id(&cx.cache),
491    };
492    let should_fully_qualify = should_fully_qualify_path(self_def_id, &trait_, &self_type);
493
494    QPathData {
495        assoc: projection_to_path_segment(proj, cx),
496        self_type,
497        should_fully_qualify,
498        trait_: Some(trait_),
499    }
500}
501
502fn should_fully_qualify_path(self_def_id: Option<DefId>, trait_: &Path, self_type: &Type) -> bool {
503    !trait_.segments.is_empty()
504        && self_def_id
505            .zip(Some(trait_.def_id()))
506            .map_or(!self_type.is_self_type(), |(id, trait_)| id != trait_)
507}
508
509fn projection_to_path_segment<'tcx>(
510    proj: ty::Binder<'tcx, ty::AliasTerm<'tcx>>,
511    cx: &mut DocContext<'tcx>,
512) -> PathSegment {
513    let def_id = proj.skip_binder().def_id;
514    let generics = cx.tcx.generics_of(def_id);
515    PathSegment {
516        name: cx.tcx.item_name(def_id),
517        args: GenericArgs::AngleBracketed {
518            args: clean_middle_generic_args(
519                cx,
520                proj.map_bound(|ty| &ty.args[generics.parent_count..]),
521                false,
522                def_id,
523            ),
524            constraints: Default::default(),
525        },
526    }
527}
528
529fn clean_generic_param_def(
530    def: &ty::GenericParamDef,
531    defaults: ParamDefaults,
532    cx: &mut DocContext<'_>,
533) -> GenericParamDef {
534    let (name, kind) = match def.kind {
535        ty::GenericParamDefKind::Lifetime => {
536            (def.name, GenericParamDefKind::Lifetime { outlives: ThinVec::new() })
537        }
538        ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
539            let default = if let ParamDefaults::Yes = defaults
540                && has_default
541            {
542                Some(clean_middle_ty(
543                    ty::Binder::dummy(cx.tcx.type_of(def.def_id).instantiate_identity()),
544                    cx,
545                    Some(def.def_id),
546                    None,
547                ))
548            } else {
549                None
550            };
551            (
552                def.name,
553                GenericParamDefKind::Type {
554                    bounds: ThinVec::new(), // These are filled in from the where-clauses.
555                    default: default.map(Box::new),
556                    synthetic,
557                },
558            )
559        }
560        ty::GenericParamDefKind::Const { has_default } => (
561            def.name,
562            GenericParamDefKind::Const {
563                ty: Box::new(clean_middle_ty(
564                    ty::Binder::dummy(
565                        cx.tcx
566                            .type_of(def.def_id)
567                            .no_bound_vars()
568                            .expect("const parameter types cannot be generic"),
569                    ),
570                    cx,
571                    Some(def.def_id),
572                    None,
573                )),
574                default: if let ParamDefaults::Yes = defaults
575                    && has_default
576                {
577                    Some(Box::new(
578                        cx.tcx.const_param_default(def.def_id).instantiate_identity().to_string(),
579                    ))
580                } else {
581                    None
582                },
583            },
584        ),
585    };
586
587    GenericParamDef { name, def_id: def.def_id, kind }
588}
589
590/// Whether to clean generic parameter defaults or not.
591enum ParamDefaults {
592    Yes,
593    No,
594}
595
596fn clean_generic_param<'tcx>(
597    cx: &mut DocContext<'tcx>,
598    generics: Option<&hir::Generics<'tcx>>,
599    param: &hir::GenericParam<'tcx>,
600) -> GenericParamDef {
601    let (name, kind) = match param.kind {
602        hir::GenericParamKind::Lifetime { .. } => {
603            let outlives = if let Some(generics) = generics {
604                generics
605                    .outlives_for_param(param.def_id)
606                    .filter(|bp| !bp.in_where_clause)
607                    .flat_map(|bp| bp.bounds)
608                    .map(|bound| match bound {
609                        hir::GenericBound::Outlives(lt) => clean_lifetime(lt, cx),
610                        _ => panic!(),
611                    })
612                    .collect()
613            } else {
614                ThinVec::new()
615            };
616            (param.name.ident().name, GenericParamDefKind::Lifetime { outlives })
617        }
618        hir::GenericParamKind::Type { ref default, synthetic } => {
619            let bounds = if let Some(generics) = generics {
620                generics
621                    .bounds_for_param(param.def_id)
622                    .filter(|bp| bp.origin != PredicateOrigin::WhereClause)
623                    .flat_map(|bp| bp.bounds)
624                    .filter_map(|x| clean_generic_bound(x, cx))
625                    .collect()
626            } else {
627                ThinVec::new()
628            };
629            (
630                param.name.ident().name,
631                GenericParamDefKind::Type {
632                    bounds,
633                    default: default.map(|t| clean_ty(t, cx)).map(Box::new),
634                    synthetic,
635                },
636            )
637        }
638        hir::GenericParamKind::Const { ty, default } => (
639            param.name.ident().name,
640            GenericParamDefKind::Const {
641                ty: Box::new(clean_ty(ty, cx)),
642                default: default.map(|ct| {
643                    Box::new(lower_const_arg_for_rustdoc(cx.tcx, ct, FeedConstTy::No).to_string())
644                }),
645            },
646        ),
647    };
648
649    GenericParamDef { name, def_id: param.def_id.to_def_id(), kind }
650}
651
652/// Synthetic type-parameters are inserted after normal ones.
653/// In order for normal parameters to be able to refer to synthetic ones,
654/// scans them first.
655fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
656    match param.kind {
657        hir::GenericParamKind::Type { synthetic, .. } => synthetic,
658        _ => false,
659    }
660}
661
662/// This can happen for `async fn`, e.g. `async fn f<'_>(&'_ self)`.
663///
664/// See `lifetime_to_generic_param` in `rustc_ast_lowering` for more information.
665fn is_elided_lifetime(param: &hir::GenericParam<'_>) -> bool {
666    matches!(
667        param.kind,
668        hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided(_) }
669    )
670}
671
672pub(crate) fn clean_generics<'tcx>(
673    gens: &hir::Generics<'tcx>,
674    cx: &mut DocContext<'tcx>,
675) -> Generics {
676    let impl_trait_params = gens
677        .params
678        .iter()
679        .filter(|param| is_impl_trait(param))
680        .map(|param| {
681            let param = clean_generic_param(cx, Some(gens), param);
682            match param.kind {
683                GenericParamDefKind::Lifetime { .. } => unreachable!(),
684                GenericParamDefKind::Type { ref bounds, .. } => {
685                    cx.impl_trait_bounds.insert(param.def_id.into(), bounds.to_vec());
686                }
687                GenericParamDefKind::Const { .. } => unreachable!(),
688            }
689            param
690        })
691        .collect::<Vec<_>>();
692
693    let mut bound_predicates = FxIndexMap::default();
694    let mut region_predicates = FxIndexMap::default();
695    let mut eq_predicates = ThinVec::default();
696    for pred in gens.predicates.iter().filter_map(|x| clean_where_predicate(x, cx)) {
697        match pred {
698            WherePredicate::BoundPredicate { ty, bounds, bound_params } => {
699                match bound_predicates.entry(ty) {
700                    IndexEntry::Vacant(v) => {
701                        v.insert((bounds, bound_params));
702                    }
703                    IndexEntry::Occupied(mut o) => {
704                        // we merge both bounds.
705                        for bound in bounds {
706                            if !o.get().0.contains(&bound) {
707                                o.get_mut().0.push(bound);
708                            }
709                        }
710                        for bound_param in bound_params {
711                            if !o.get().1.contains(&bound_param) {
712                                o.get_mut().1.push(bound_param);
713                            }
714                        }
715                    }
716                }
717            }
718            WherePredicate::RegionPredicate { lifetime, bounds } => {
719                match region_predicates.entry(lifetime) {
720                    IndexEntry::Vacant(v) => {
721                        v.insert(bounds);
722                    }
723                    IndexEntry::Occupied(mut o) => {
724                        // we merge both bounds.
725                        for bound in bounds {
726                            if !o.get().contains(&bound) {
727                                o.get_mut().push(bound);
728                            }
729                        }
730                    }
731                }
732            }
733            WherePredicate::EqPredicate { lhs, rhs } => {
734                eq_predicates.push(WherePredicate::EqPredicate { lhs, rhs });
735            }
736        }
737    }
738
739    let mut params = ThinVec::with_capacity(gens.params.len());
740    // In this loop, we gather the generic parameters (`<'a, B: 'a>`) and check if they have
741    // bounds in the where predicates. If so, we move their bounds into the where predicates
742    // while also preventing duplicates.
743    for p in gens.params.iter().filter(|p| !is_impl_trait(p) && !is_elided_lifetime(p)) {
744        let mut p = clean_generic_param(cx, Some(gens), p);
745        match &mut p.kind {
746            GenericParamDefKind::Lifetime { outlives } => {
747                if let Some(region_pred) = region_predicates.get_mut(&Lifetime(p.name)) {
748                    // We merge bounds in the `where` clause.
749                    for outlive in outlives.drain(..) {
750                        let outlive = GenericBound::Outlives(outlive);
751                        if !region_pred.contains(&outlive) {
752                            region_pred.push(outlive);
753                        }
754                    }
755                }
756            }
757            GenericParamDefKind::Type { bounds, synthetic: false, .. } => {
758                if let Some(bound_pred) = bound_predicates.get_mut(&Type::Generic(p.name)) {
759                    // We merge bounds in the `where` clause.
760                    for bound in bounds.drain(..) {
761                        if !bound_pred.0.contains(&bound) {
762                            bound_pred.0.push(bound);
763                        }
764                    }
765                }
766            }
767            GenericParamDefKind::Type { .. } | GenericParamDefKind::Const { .. } => {
768                // nothing to do here.
769            }
770        }
771        params.push(p);
772    }
773    params.extend(impl_trait_params);
774
775    Generics {
776        params,
777        where_predicates: bound_predicates
778            .into_iter()
779            .map(|(ty, (bounds, bound_params))| WherePredicate::BoundPredicate {
780                ty,
781                bounds,
782                bound_params,
783            })
784            .chain(
785                region_predicates
786                    .into_iter()
787                    .map(|(lifetime, bounds)| WherePredicate::RegionPredicate { lifetime, bounds }),
788            )
789            .chain(eq_predicates)
790            .collect(),
791    }
792}
793
794fn clean_ty_generics<'tcx>(cx: &mut DocContext<'tcx>, def_id: DefId) -> Generics {
795    clean_ty_generics_inner(cx, cx.tcx.generics_of(def_id), cx.tcx.explicit_predicates_of(def_id))
796}
797
798fn clean_ty_generics_inner<'tcx>(
799    cx: &mut DocContext<'tcx>,
800    gens: &ty::Generics,
801    preds: ty::GenericPredicates<'tcx>,
802) -> Generics {
803    // Don't populate `cx.impl_trait_bounds` before cleaning where clauses,
804    // since `clean_predicate` would consume them.
805    let mut impl_trait = BTreeMap::<u32, Vec<GenericBound>>::default();
806
807    let params: ThinVec<_> = gens
808        .own_params
809        .iter()
810        .filter(|param| match param.kind {
811            ty::GenericParamDefKind::Lifetime => !param.is_anonymous_lifetime(),
812            ty::GenericParamDefKind::Type { synthetic, .. } => {
813                if param.name == kw::SelfUpper {
814                    debug_assert_eq!(param.index, 0);
815                    return false;
816                }
817                if synthetic {
818                    impl_trait.insert(param.index, vec![]);
819                    return false;
820                }
821                true
822            }
823            ty::GenericParamDefKind::Const { .. } => true,
824        })
825        .map(|param| clean_generic_param_def(param, ParamDefaults::Yes, cx))
826        .collect();
827
828    // param index -> [(trait DefId, associated type name & generics, term)]
829    let mut impl_trait_proj =
830        FxHashMap::<u32, Vec<(DefId, PathSegment, ty::Binder<'_, ty::Term<'_>>)>>::default();
831
832    let where_predicates = preds
833        .predicates
834        .iter()
835        .flat_map(|(pred, _)| {
836            let mut proj_pred = None;
837            let param_idx = {
838                let bound_p = pred.kind();
839                match bound_p.skip_binder() {
840                    ty::ClauseKind::Trait(pred) if let ty::Param(param) = pred.self_ty().kind() => {
841                        Some(param.index)
842                    }
843                    ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(ty, _reg))
844                        if let ty::Param(param) = ty.kind() =>
845                    {
846                        Some(param.index)
847                    }
848                    ty::ClauseKind::Projection(p)
849                        if let ty::Param(param) = p.projection_term.self_ty().kind() =>
850                    {
851                        proj_pred = Some(bound_p.rebind(p));
852                        Some(param.index)
853                    }
854                    _ => None,
855                }
856            };
857
858            if let Some(param_idx) = param_idx
859                && let Some(bounds) = impl_trait.get_mut(&param_idx)
860            {
861                let pred = clean_predicate(*pred, cx)?;
862
863                bounds.extend(pred.get_bounds().into_iter().flatten().cloned());
864
865                if let Some(pred) = proj_pred {
866                    let lhs = clean_projection(pred.map_bound(|p| p.projection_term), cx, None);
867                    impl_trait_proj.entry(param_idx).or_default().push((
868                        lhs.trait_.unwrap().def_id(),
869                        lhs.assoc,
870                        pred.map_bound(|p| p.term),
871                    ));
872                }
873
874                return None;
875            }
876
877            Some(pred)
878        })
879        .collect::<Vec<_>>();
880
881    for (idx, mut bounds) in impl_trait {
882        let mut has_sized = false;
883        bounds.retain(|b| {
884            if b.is_sized_bound(cx) {
885                has_sized = true;
886                false
887            } else if b.is_meta_sized_bound(cx) {
888                // FIXME(sized-hierarchy): Always skip `MetaSized` bounds so that only `?Sized`
889                // is shown and none of the new sizedness traits leak into documentation.
890                false
891            } else {
892                true
893            }
894        });
895        if !has_sized {
896            bounds.push(GenericBound::maybe_sized(cx));
897        }
898
899        // Move trait bounds to the front.
900        bounds.sort_by_key(|b| !b.is_trait_bound());
901
902        // Add back a `Sized` bound if there are no *trait* bounds remaining (incl. `?Sized`).
903        // Since all potential trait bounds are at the front we can just check the first bound.
904        if bounds.first().is_none_or(|b| !b.is_trait_bound()) {
905            bounds.insert(0, GenericBound::sized(cx));
906        }
907
908        if let Some(proj) = impl_trait_proj.remove(&idx) {
909            for (trait_did, name, rhs) in proj {
910                let rhs = clean_middle_term(rhs, cx);
911                simplify::merge_bounds(cx, &mut bounds, trait_did, name, &rhs);
912            }
913        }
914
915        cx.impl_trait_bounds.insert(idx.into(), bounds);
916    }
917
918    // Now that `cx.impl_trait_bounds` is populated, we can process
919    // remaining predicates which could contain `impl Trait`.
920    let where_predicates =
921        where_predicates.into_iter().flat_map(|p| clean_predicate(*p, cx)).collect();
922
923    let mut generics = Generics { params, where_predicates };
924    simplify::sized_bounds(cx, &mut generics);
925    generics.where_predicates = simplify::where_clauses(cx, generics.where_predicates);
926    generics
927}
928
929fn clean_ty_alias_inner_type<'tcx>(
930    ty: Ty<'tcx>,
931    cx: &mut DocContext<'tcx>,
932    ret: &mut Vec<Item>,
933) -> Option<TypeAliasInnerType> {
934    let ty::Adt(adt_def, args) = ty.kind() else {
935        return None;
936    };
937
938    if !adt_def.did().is_local() {
939        cx.with_param_env(adt_def.did(), |cx| {
940            inline::build_impls(cx, adt_def.did(), None, ret);
941        });
942    }
943
944    Some(if adt_def.is_enum() {
945        let variants: rustc_index::IndexVec<_, _> = adt_def
946            .variants()
947            .iter()
948            .map(|variant| clean_variant_def_with_args(variant, args, cx))
949            .collect();
950
951        if !adt_def.did().is_local() {
952            inline::record_extern_fqn(cx, adt_def.did(), ItemType::Enum);
953        }
954
955        TypeAliasInnerType::Enum {
956            variants,
957            is_non_exhaustive: adt_def.is_variant_list_non_exhaustive(),
958        }
959    } else {
960        let variant = adt_def
961            .variants()
962            .iter()
963            .next()
964            .unwrap_or_else(|| bug!("a struct or union should always have one variant def"));
965
966        let fields: Vec<_> =
967            clean_variant_def_with_args(variant, args, cx).kind.inner_items().cloned().collect();
968
969        if adt_def.is_struct() {
970            if !adt_def.did().is_local() {
971                inline::record_extern_fqn(cx, adt_def.did(), ItemType::Struct);
972            }
973            TypeAliasInnerType::Struct { ctor_kind: variant.ctor_kind(), fields }
974        } else {
975            if !adt_def.did().is_local() {
976                inline::record_extern_fqn(cx, adt_def.did(), ItemType::Union);
977            }
978            TypeAliasInnerType::Union { fields }
979        }
980    })
981}
982
983fn clean_proc_macro<'tcx>(
984    item: &hir::Item<'tcx>,
985    name: &mut Symbol,
986    kind: MacroKind,
987    cx: &mut DocContext<'tcx>,
988) -> ItemKind {
989    if kind != MacroKind::Derive {
990        return ProcMacroItem(ProcMacro { kind, helpers: vec![] });
991    }
992    let attrs = cx.tcx.hir_attrs(item.hir_id());
993    let Some((trait_name, helper_attrs)) = find_attr!(attrs, AttributeKind::ProcMacroDerive { trait_name, helper_attrs, ..} => (*trait_name, helper_attrs))
994    else {
995        return ProcMacroItem(ProcMacro { kind, helpers: vec![] });
996    };
997    *name = trait_name;
998    let helpers = helper_attrs.iter().copied().collect();
999
1000    ProcMacroItem(ProcMacro { kind, helpers })
1001}
1002
1003fn clean_fn_or_proc_macro<'tcx>(
1004    item: &hir::Item<'tcx>,
1005    sig: &hir::FnSig<'tcx>,
1006    generics: &hir::Generics<'tcx>,
1007    body_id: hir::BodyId,
1008    name: &mut Symbol,
1009    cx: &mut DocContext<'tcx>,
1010) -> ItemKind {
1011    let attrs = cx.tcx.hir_attrs(item.hir_id());
1012    let macro_kind = if find_attr!(attrs, AttributeKind::ProcMacro(..)) {
1013        Some(MacroKind::Bang)
1014    } else if find_attr!(attrs, AttributeKind::ProcMacroDerive { .. }) {
1015        Some(MacroKind::Derive)
1016    } else if find_attr!(attrs, AttributeKind::ProcMacroAttribute(..)) {
1017        Some(MacroKind::Attr)
1018    } else {
1019        None
1020    };
1021
1022    match macro_kind {
1023        Some(kind) => clean_proc_macro(item, name, kind, cx),
1024        None => {
1025            let mut func = clean_function(cx, sig, generics, ParamsSrc::Body(body_id));
1026            clean_fn_decl_legacy_const_generics(&mut func, attrs);
1027            FunctionItem(func)
1028        }
1029    }
1030}
1031
1032/// This is needed to make it more "readable" when documenting functions using
1033/// `rustc_legacy_const_generics`. More information in
1034/// <https://github.com/rust-lang/rust/issues/83167>.
1035fn clean_fn_decl_legacy_const_generics(func: &mut Function, attrs: &[hir::Attribute]) {
1036    for meta_item_list in attrs
1037        .iter()
1038        .filter(|a| a.has_name(sym::rustc_legacy_const_generics))
1039        .filter_map(|a| a.meta_item_list())
1040    {
1041        for (pos, literal) in meta_item_list.iter().filter_map(|meta| meta.lit()).enumerate() {
1042            match literal.kind {
1043                ast::LitKind::Int(a, _) => {
1044                    let GenericParamDef { name, kind, .. } = func.generics.params.remove(0);
1045                    if let GenericParamDefKind::Const { ty, .. } = kind {
1046                        func.decl.inputs.insert(
1047                            a.get() as _,
1048                            Parameter { name: Some(name), type_: *ty, is_const: true },
1049                        );
1050                    } else {
1051                        panic!("unexpected non const in position {pos}");
1052                    }
1053                }
1054                _ => panic!("invalid arg index"),
1055            }
1056        }
1057    }
1058}
1059
1060enum ParamsSrc<'tcx> {
1061    Body(hir::BodyId),
1062    Idents(&'tcx [Option<Ident>]),
1063}
1064
1065fn clean_function<'tcx>(
1066    cx: &mut DocContext<'tcx>,
1067    sig: &hir::FnSig<'tcx>,
1068    generics: &hir::Generics<'tcx>,
1069    params: ParamsSrc<'tcx>,
1070) -> Box<Function> {
1071    let (generics, decl) = enter_impl_trait(cx, |cx| {
1072        // NOTE: Generics must be cleaned before params.
1073        let generics = clean_generics(generics, cx);
1074        let params = match params {
1075            ParamsSrc::Body(body_id) => clean_params_via_body(cx, sig.decl.inputs, body_id),
1076            // Let's not perpetuate anon params from Rust 2015; use `_` for them.
1077            ParamsSrc::Idents(idents) => clean_params(cx, sig.decl.inputs, idents, |ident| {
1078                Some(ident.map_or(kw::Underscore, |ident| ident.name))
1079            }),
1080        };
1081        let decl = clean_fn_decl_with_params(cx, sig.decl, Some(&sig.header), params);
1082        (generics, decl)
1083    });
1084    Box::new(Function { decl, generics })
1085}
1086
1087fn clean_params<'tcx>(
1088    cx: &mut DocContext<'tcx>,
1089    types: &[hir::Ty<'tcx>],
1090    idents: &[Option<Ident>],
1091    postprocess: impl Fn(Option<Ident>) -> Option<Symbol>,
1092) -> Vec<Parameter> {
1093    types
1094        .iter()
1095        .enumerate()
1096        .map(|(i, ty)| Parameter {
1097            name: postprocess(idents[i]),
1098            type_: clean_ty(ty, cx),
1099            is_const: false,
1100        })
1101        .collect()
1102}
1103
1104fn clean_params_via_body<'tcx>(
1105    cx: &mut DocContext<'tcx>,
1106    types: &[hir::Ty<'tcx>],
1107    body_id: hir::BodyId,
1108) -> Vec<Parameter> {
1109    types
1110        .iter()
1111        .zip(cx.tcx.hir_body(body_id).params)
1112        .map(|(ty, param)| Parameter {
1113            name: Some(name_from_pat(param.pat)),
1114            type_: clean_ty(ty, cx),
1115            is_const: false,
1116        })
1117        .collect()
1118}
1119
1120fn clean_fn_decl_with_params<'tcx>(
1121    cx: &mut DocContext<'tcx>,
1122    decl: &hir::FnDecl<'tcx>,
1123    header: Option<&hir::FnHeader>,
1124    params: Vec<Parameter>,
1125) -> FnDecl {
1126    let mut output = match decl.output {
1127        hir::FnRetTy::Return(typ) => clean_ty(typ, cx),
1128        hir::FnRetTy::DefaultReturn(..) => Type::Tuple(Vec::new()),
1129    };
1130    if let Some(header) = header
1131        && header.is_async()
1132    {
1133        output = output.sugared_async_return_type();
1134    }
1135    FnDecl { inputs: params, output, c_variadic: decl.c_variadic }
1136}
1137
1138fn clean_poly_fn_sig<'tcx>(
1139    cx: &mut DocContext<'tcx>,
1140    did: Option<DefId>,
1141    sig: ty::PolyFnSig<'tcx>,
1142) -> FnDecl {
1143    let mut output = clean_middle_ty(sig.output(), cx, None, None);
1144
1145    // If the return type isn't an `impl Trait`, we can safely assume that this
1146    // function isn't async without needing to execute the query `asyncness` at
1147    // all which gives us a noticeable performance boost.
1148    if let Some(did) = did
1149        && let Type::ImplTrait(_) = output
1150        && cx.tcx.asyncness(did).is_async()
1151    {
1152        output = output.sugared_async_return_type();
1153    }
1154
1155    let mut idents = did.map(|did| cx.tcx.fn_arg_idents(did)).unwrap_or_default().iter().copied();
1156
1157    // If this comes from a fn item, let's not perpetuate anon params from Rust 2015; use `_` for them.
1158    // If this comes from a fn ptr ty, we just keep params unnamed since it's more conventional stylistically.
1159    // Since the param name is not part of the semantic type, these params never bear a name unlike
1160    // in the HIR case, thus we can't perform any fancy fallback logic unlike `clean_bare_fn_ty`.
1161    let fallback = did.map(|_| kw::Underscore);
1162
1163    let params = sig
1164        .inputs()
1165        .iter()
1166        .map(|ty| Parameter {
1167            name: idents.next().flatten().map(|ident| ident.name).or(fallback),
1168            type_: clean_middle_ty(ty.map_bound(|ty| *ty), cx, None, None),
1169            is_const: false,
1170        })
1171        .collect();
1172
1173    FnDecl { inputs: params, output, c_variadic: sig.skip_binder().c_variadic }
1174}
1175
1176fn clean_trait_ref<'tcx>(trait_ref: &hir::TraitRef<'tcx>, cx: &mut DocContext<'tcx>) -> Path {
1177    let path = clean_path(trait_ref.path, cx);
1178    register_res(cx, path.res);
1179    path
1180}
1181
1182fn clean_poly_trait_ref<'tcx>(
1183    poly_trait_ref: &hir::PolyTraitRef<'tcx>,
1184    cx: &mut DocContext<'tcx>,
1185) -> PolyTrait {
1186    PolyTrait {
1187        trait_: clean_trait_ref(&poly_trait_ref.trait_ref, cx),
1188        generic_params: poly_trait_ref
1189            .bound_generic_params
1190            .iter()
1191            .filter(|p| !is_elided_lifetime(p))
1192            .map(|x| clean_generic_param(cx, None, x))
1193            .collect(),
1194    }
1195}
1196
1197fn clean_trait_item<'tcx>(trait_item: &hir::TraitItem<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
1198    let local_did = trait_item.owner_id.to_def_id();
1199    cx.with_param_env(local_did, |cx| {
1200        let inner = match trait_item.kind {
1201            hir::TraitItemKind::Const(ty, Some(default)) => {
1202                ProvidedAssocConstItem(Box::new(Constant {
1203                    generics: enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx)),
1204                    kind: ConstantKind::Local { def_id: local_did, body: default },
1205                    type_: clean_ty(ty, cx),
1206                }))
1207            }
1208            hir::TraitItemKind::Const(ty, None) => {
1209                let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
1210                RequiredAssocConstItem(generics, Box::new(clean_ty(ty, cx)))
1211            }
1212            hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
1213                let m = clean_function(cx, sig, trait_item.generics, ParamsSrc::Body(body));
1214                MethodItem(m, None)
1215            }
1216            hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(idents)) => {
1217                let m = clean_function(cx, sig, trait_item.generics, ParamsSrc::Idents(idents));
1218                RequiredMethodItem(m)
1219            }
1220            hir::TraitItemKind::Type(bounds, Some(default)) => {
1221                let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
1222                let bounds = bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect();
1223                let item_type =
1224                    clean_middle_ty(ty::Binder::dummy(lower_ty(cx.tcx, default)), cx, None, None);
1225                AssocTypeItem(
1226                    Box::new(TypeAlias {
1227                        type_: clean_ty(default, cx),
1228                        generics,
1229                        inner_type: None,
1230                        item_type: Some(item_type),
1231                    }),
1232                    bounds,
1233                )
1234            }
1235            hir::TraitItemKind::Type(bounds, None) => {
1236                let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
1237                let bounds = bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect();
1238                RequiredAssocTypeItem(generics, bounds)
1239            }
1240        };
1241        Item::from_def_id_and_parts(local_did, Some(trait_item.ident.name), inner, cx)
1242    })
1243}
1244
1245pub(crate) fn clean_impl_item<'tcx>(
1246    impl_: &hir::ImplItem<'tcx>,
1247    cx: &mut DocContext<'tcx>,
1248) -> Item {
1249    let local_did = impl_.owner_id.to_def_id();
1250    cx.with_param_env(local_did, |cx| {
1251        let inner = match impl_.kind {
1252            hir::ImplItemKind::Const(ty, expr) => ImplAssocConstItem(Box::new(Constant {
1253                generics: clean_generics(impl_.generics, cx),
1254                kind: ConstantKind::Local { def_id: local_did, body: expr },
1255                type_: clean_ty(ty, cx),
1256            })),
1257            hir::ImplItemKind::Fn(ref sig, body) => {
1258                let m = clean_function(cx, sig, impl_.generics, ParamsSrc::Body(body));
1259                let defaultness = cx.tcx.defaultness(impl_.owner_id);
1260                MethodItem(m, Some(defaultness))
1261            }
1262            hir::ImplItemKind::Type(hir_ty) => {
1263                let type_ = clean_ty(hir_ty, cx);
1264                let generics = clean_generics(impl_.generics, cx);
1265                let item_type =
1266                    clean_middle_ty(ty::Binder::dummy(lower_ty(cx.tcx, hir_ty)), cx, None, None);
1267                AssocTypeItem(
1268                    Box::new(TypeAlias {
1269                        type_,
1270                        generics,
1271                        inner_type: None,
1272                        item_type: Some(item_type),
1273                    }),
1274                    Vec::new(),
1275                )
1276            }
1277        };
1278
1279        Item::from_def_id_and_parts(local_did, Some(impl_.ident.name), inner, cx)
1280    })
1281}
1282
1283pub(crate) fn clean_middle_assoc_item(assoc_item: &ty::AssocItem, cx: &mut DocContext<'_>) -> Item {
1284    let tcx = cx.tcx;
1285    let kind = match assoc_item.kind {
1286        ty::AssocKind::Const { .. } => {
1287            let ty = clean_middle_ty(
1288                ty::Binder::dummy(tcx.type_of(assoc_item.def_id).instantiate_identity()),
1289                cx,
1290                Some(assoc_item.def_id),
1291                None,
1292            );
1293
1294            let mut generics = clean_ty_generics(cx, assoc_item.def_id);
1295            simplify::move_bounds_to_generic_parameters(&mut generics);
1296
1297            match assoc_item.container {
1298                ty::AssocItemContainer::Impl => ImplAssocConstItem(Box::new(Constant {
1299                    generics,
1300                    kind: ConstantKind::Extern { def_id: assoc_item.def_id },
1301                    type_: ty,
1302                })),
1303                ty::AssocItemContainer::Trait => {
1304                    if tcx.defaultness(assoc_item.def_id).has_value() {
1305                        ProvidedAssocConstItem(Box::new(Constant {
1306                            generics,
1307                            kind: ConstantKind::Extern { def_id: assoc_item.def_id },
1308                            type_: ty,
1309                        }))
1310                    } else {
1311                        RequiredAssocConstItem(generics, Box::new(ty))
1312                    }
1313                }
1314            }
1315        }
1316        ty::AssocKind::Fn { has_self, .. } => {
1317            let mut item = inline::build_function(cx, assoc_item.def_id);
1318
1319            if has_self {
1320                let self_ty = match assoc_item.container {
1321                    ty::AssocItemContainer::Impl => {
1322                        tcx.type_of(assoc_item.container_id(tcx)).instantiate_identity()
1323                    }
1324                    ty::AssocItemContainer::Trait => tcx.types.self_param,
1325                };
1326                let self_param_ty =
1327                    tcx.fn_sig(assoc_item.def_id).instantiate_identity().input(0).skip_binder();
1328                if self_param_ty == self_ty {
1329                    item.decl.inputs[0].type_ = SelfTy;
1330                } else if let ty::Ref(_, ty, _) = *self_param_ty.kind()
1331                    && ty == self_ty
1332                {
1333                    match item.decl.inputs[0].type_ {
1334                        BorrowedRef { ref mut type_, .. } => **type_ = SelfTy,
1335                        _ => unreachable!(),
1336                    }
1337                }
1338            }
1339
1340            let provided = match assoc_item.container {
1341                ty::AssocItemContainer::Impl => true,
1342                ty::AssocItemContainer::Trait => assoc_item.defaultness(tcx).has_value(),
1343            };
1344            if provided {
1345                let defaultness = match assoc_item.container {
1346                    ty::AssocItemContainer::Impl => Some(assoc_item.defaultness(tcx)),
1347                    ty::AssocItemContainer::Trait => None,
1348                };
1349                MethodItem(item, defaultness)
1350            } else {
1351                RequiredMethodItem(item)
1352            }
1353        }
1354        ty::AssocKind::Type { .. } => {
1355            let my_name = assoc_item.name();
1356
1357            fn param_eq_arg(param: &GenericParamDef, arg: &GenericArg) -> bool {
1358                match (&param.kind, arg) {
1359                    (GenericParamDefKind::Type { .. }, GenericArg::Type(Type::Generic(ty)))
1360                        if *ty == param.name =>
1361                    {
1362                        true
1363                    }
1364                    (GenericParamDefKind::Lifetime { .. }, GenericArg::Lifetime(Lifetime(lt)))
1365                        if *lt == param.name =>
1366                    {
1367                        true
1368                    }
1369                    (GenericParamDefKind::Const { .. }, GenericArg::Const(c)) => match &**c {
1370                        ConstantKind::TyConst { expr } => **expr == *param.name.as_str(),
1371                        _ => false,
1372                    },
1373                    _ => false,
1374                }
1375            }
1376
1377            let mut predicates = tcx.explicit_predicates_of(assoc_item.def_id).predicates;
1378            if let ty::AssocItemContainer::Trait = assoc_item.container {
1379                let bounds = tcx.explicit_item_bounds(assoc_item.def_id).iter_identity_copied();
1380                predicates = tcx.arena.alloc_from_iter(bounds.chain(predicates.iter().copied()));
1381            }
1382            let mut generics = clean_ty_generics_inner(
1383                cx,
1384                tcx.generics_of(assoc_item.def_id),
1385                ty::GenericPredicates { parent: None, predicates },
1386            );
1387            simplify::move_bounds_to_generic_parameters(&mut generics);
1388
1389            if let ty::AssocItemContainer::Trait = assoc_item.container {
1390                // Move bounds that are (likely) directly attached to the associated type
1391                // from the where-clause to the associated type.
1392                // There is no guarantee that this is what the user actually wrote but we have
1393                // no way of knowing.
1394                let mut bounds: Vec<GenericBound> = Vec::new();
1395                generics.where_predicates.retain_mut(|pred| match *pred {
1396                    WherePredicate::BoundPredicate {
1397                        ty:
1398                            QPath(box QPathData {
1399                                ref assoc,
1400                                ref self_type,
1401                                trait_: Some(ref trait_),
1402                                ..
1403                            }),
1404                        bounds: ref mut pred_bounds,
1405                        ..
1406                    } => {
1407                        if assoc.name != my_name {
1408                            return true;
1409                        }
1410                        if trait_.def_id() != assoc_item.container_id(tcx) {
1411                            return true;
1412                        }
1413                        if *self_type != SelfTy {
1414                            return true;
1415                        }
1416                        match &assoc.args {
1417                            GenericArgs::AngleBracketed { args, constraints } => {
1418                                if !constraints.is_empty()
1419                                    || generics
1420                                        .params
1421                                        .iter()
1422                                        .zip(args.iter())
1423                                        .any(|(param, arg)| !param_eq_arg(param, arg))
1424                                {
1425                                    return true;
1426                                }
1427                            }
1428                            GenericArgs::Parenthesized { .. } => {
1429                                // The only time this happens is if we're inside the rustdoc for Fn(),
1430                                // which only has one associated type, which is not a GAT, so whatever.
1431                            }
1432                            GenericArgs::ReturnTypeNotation => {
1433                                // Never move these.
1434                            }
1435                        }
1436                        bounds.extend(mem::take(pred_bounds));
1437                        false
1438                    }
1439                    _ => true,
1440                });
1441
1442                bounds.retain(|b| {
1443                    // FIXME(sized-hierarchy): Always skip `MetaSized` bounds so that only `?Sized`
1444                    // is shown and none of the new sizedness traits leak into documentation.
1445                    !b.is_meta_sized_bound(cx)
1446                });
1447
1448                // Our Sized/?Sized bound didn't get handled when creating the generics
1449                // because we didn't actually get our whole set of bounds until just now
1450                // (some of them may have come from the trait). If we do have a sized
1451                // bound, we remove it, and if we don't then we add the `?Sized` bound
1452                // at the end.
1453                match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1454                    Some(i) => {
1455                        bounds.remove(i);
1456                    }
1457                    None => bounds.push(GenericBound::maybe_sized(cx)),
1458                }
1459
1460                if tcx.defaultness(assoc_item.def_id).has_value() {
1461                    AssocTypeItem(
1462                        Box::new(TypeAlias {
1463                            type_: clean_middle_ty(
1464                                ty::Binder::dummy(
1465                                    tcx.type_of(assoc_item.def_id).instantiate_identity(),
1466                                ),
1467                                cx,
1468                                Some(assoc_item.def_id),
1469                                None,
1470                            ),
1471                            generics,
1472                            inner_type: None,
1473                            item_type: None,
1474                        }),
1475                        bounds,
1476                    )
1477                } else {
1478                    RequiredAssocTypeItem(generics, bounds)
1479                }
1480            } else {
1481                AssocTypeItem(
1482                    Box::new(TypeAlias {
1483                        type_: clean_middle_ty(
1484                            ty::Binder::dummy(
1485                                tcx.type_of(assoc_item.def_id).instantiate_identity(),
1486                            ),
1487                            cx,
1488                            Some(assoc_item.def_id),
1489                            None,
1490                        ),
1491                        generics,
1492                        inner_type: None,
1493                        item_type: None,
1494                    }),
1495                    // Associated types inside trait or inherent impls are not allowed to have
1496                    // item bounds. Thus we don't attempt to move any bounds there.
1497                    Vec::new(),
1498                )
1499            }
1500        }
1501    };
1502
1503    Item::from_def_id_and_parts(assoc_item.def_id, Some(assoc_item.name()), kind, cx)
1504}
1505
1506fn first_non_private_clean_path<'tcx>(
1507    cx: &mut DocContext<'tcx>,
1508    path: &hir::Path<'tcx>,
1509    new_path_segments: &'tcx [hir::PathSegment<'tcx>],
1510    new_path_span: rustc_span::Span,
1511) -> Path {
1512    let new_hir_path =
1513        hir::Path { segments: new_path_segments, res: path.res, span: new_path_span };
1514    let mut new_clean_path = clean_path(&new_hir_path, cx);
1515    // In here we need to play with the path data one last time to provide it the
1516    // missing `args` and `res` of the final `Path` we get, which, since it comes
1517    // from a re-export, doesn't have the generics that were originally there, so
1518    // we add them by hand.
1519    if let Some(path_last) = path.segments.last().as_ref()
1520        && let Some(new_path_last) = new_clean_path.segments[..].last_mut()
1521        && let Some(path_last_args) = path_last.args.as_ref()
1522        && path_last.args.is_some()
1523    {
1524        assert!(new_path_last.args.is_empty());
1525        new_path_last.args = clean_generic_args(path_last_args, cx);
1526    }
1527    new_clean_path
1528}
1529
1530/// The goal of this function is to return the first `Path` which is not private (ie not private
1531/// or `doc(hidden)`). If it's not possible, it'll return the "end type".
1532///
1533/// If the path is not a re-export or is public, it'll return `None`.
1534fn first_non_private<'tcx>(
1535    cx: &mut DocContext<'tcx>,
1536    hir_id: hir::HirId,
1537    path: &hir::Path<'tcx>,
1538) -> Option<Path> {
1539    let target_def_id = path.res.opt_def_id()?;
1540    let (parent_def_id, ident) = match &path.segments {
1541        [] => return None,
1542        // Relative paths are available in the same scope as the owner.
1543        [leaf] => (cx.tcx.local_parent(hir_id.owner.def_id), leaf.ident),
1544        // So are self paths.
1545        [parent, leaf] if parent.ident.name == kw::SelfLower => {
1546            (cx.tcx.local_parent(hir_id.owner.def_id), leaf.ident)
1547        }
1548        // Crate paths are not. We start from the crate root.
1549        [parent, leaf] if matches!(parent.ident.name, kw::Crate | kw::PathRoot) => {
1550            (LOCAL_CRATE.as_def_id().as_local()?, leaf.ident)
1551        }
1552        [parent, leaf] if parent.ident.name == kw::Super => {
1553            let parent_mod = cx.tcx.parent_module(hir_id);
1554            if let Some(super_parent) = cx.tcx.opt_local_parent(parent_mod.to_local_def_id()) {
1555                (super_parent, leaf.ident)
1556            } else {
1557                // If we can't find the parent of the parent, then the parent is already the crate.
1558                (LOCAL_CRATE.as_def_id().as_local()?, leaf.ident)
1559            }
1560        }
1561        // Absolute paths are not. We start from the parent of the item.
1562        [.., parent, leaf] => (parent.res.opt_def_id()?.as_local()?, leaf.ident),
1563    };
1564    // First we try to get the `DefId` of the item.
1565    for child in
1566        cx.tcx.module_children_local(parent_def_id).iter().filter(move |c| c.ident == ident)
1567    {
1568        if let Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) = child.res {
1569            continue;
1570        }
1571
1572        if let Some(def_id) = child.res.opt_def_id()
1573            && target_def_id == def_id
1574        {
1575            let mut last_path_res = None;
1576            'reexps: for reexp in child.reexport_chain.iter() {
1577                if let Some(use_def_id) = reexp.id()
1578                    && let Some(local_use_def_id) = use_def_id.as_local()
1579                    && let hir::Node::Item(item) = cx.tcx.hir_node_by_def_id(local_use_def_id)
1580                    && let hir::ItemKind::Use(path, hir::UseKind::Single(_)) = item.kind
1581                {
1582                    for res in path.res.present_items() {
1583                        if let Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) = res {
1584                            continue;
1585                        }
1586                        if (cx.render_options.document_hidden ||
1587                            !cx.tcx.is_doc_hidden(use_def_id)) &&
1588                            // We never check for "cx.render_options.document_private"
1589                            // because if a re-export is not fully public, it's never
1590                            // documented.
1591                            cx.tcx.local_visibility(local_use_def_id).is_public()
1592                        {
1593                            break 'reexps;
1594                        }
1595                        last_path_res = Some((path, res));
1596                        continue 'reexps;
1597                    }
1598                }
1599            }
1600            if !child.reexport_chain.is_empty() {
1601                // So in here, we use the data we gathered from iterating the reexports. If
1602                // `last_path_res` is set, it can mean two things:
1603                //
1604                // 1. We found a public reexport.
1605                // 2. We didn't find a public reexport so it's the "end type" path.
1606                if let Some((new_path, _)) = last_path_res {
1607                    return Some(first_non_private_clean_path(
1608                        cx,
1609                        path,
1610                        new_path.segments,
1611                        new_path.span,
1612                    ));
1613                }
1614                // If `last_path_res` is `None`, it can mean two things:
1615                //
1616                // 1. The re-export is public, no need to change anything, just use the path as is.
1617                // 2. Nothing was found, so let's just return the original path.
1618                return None;
1619            }
1620        }
1621    }
1622    None
1623}
1624
1625fn clean_qpath<'tcx>(hir_ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1626    let hir::Ty { hir_id, span, ref kind } = *hir_ty;
1627    let hir::TyKind::Path(qpath) = kind else { unreachable!() };
1628
1629    match qpath {
1630        hir::QPath::Resolved(None, path) => {
1631            if let Res::Def(DefKind::TyParam, did) = path.res {
1632                if let Some(new_ty) = cx.args.get(&did).and_then(|p| p.as_ty()).cloned() {
1633                    return new_ty;
1634                }
1635                if let Some(bounds) = cx.impl_trait_bounds.remove(&did.into()) {
1636                    return ImplTrait(bounds);
1637                }
1638            }
1639
1640            if let Some(expanded) = maybe_expand_private_type_alias(cx, path) {
1641                expanded
1642            } else {
1643                // First we check if it's a private re-export.
1644                let path = if let Some(path) = first_non_private(cx, hir_id, path) {
1645                    path
1646                } else {
1647                    clean_path(path, cx)
1648                };
1649                resolve_type(cx, path)
1650            }
1651        }
1652        hir::QPath::Resolved(Some(qself), p) => {
1653            // Try to normalize `<X as Y>::T` to a type
1654            let ty = lower_ty(cx.tcx, hir_ty);
1655            // `hir_to_ty` can return projection types with escaping vars for GATs, e.g. `<() as Trait>::Gat<'_>`
1656            if !ty.has_escaping_bound_vars()
1657                && let Some(normalized_value) = normalize(cx, ty::Binder::dummy(ty))
1658            {
1659                return clean_middle_ty(normalized_value, cx, None, None);
1660            }
1661
1662            let trait_segments = &p.segments[..p.segments.len() - 1];
1663            let trait_def = cx.tcx.parent(p.res.def_id());
1664            let trait_ = self::Path {
1665                res: Res::Def(DefKind::Trait, trait_def),
1666                segments: trait_segments.iter().map(|x| clean_path_segment(x, cx)).collect(),
1667            };
1668            register_res(cx, trait_.res);
1669            let self_def_id = DefId::local(qself.hir_id.owner.def_id.local_def_index);
1670            let self_type = clean_ty(qself, cx);
1671            let should_fully_qualify =
1672                should_fully_qualify_path(Some(self_def_id), &trait_, &self_type);
1673            Type::QPath(Box::new(QPathData {
1674                assoc: clean_path_segment(p.segments.last().expect("segments were empty"), cx),
1675                should_fully_qualify,
1676                self_type,
1677                trait_: Some(trait_),
1678            }))
1679        }
1680        hir::QPath::TypeRelative(qself, segment) => {
1681            let ty = lower_ty(cx.tcx, hir_ty);
1682            let self_type = clean_ty(qself, cx);
1683
1684            let (trait_, should_fully_qualify) = match ty.kind() {
1685                ty::Alias(ty::Projection, proj) => {
1686                    let res = Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id);
1687                    let trait_ = clean_path(&hir::Path { span, res, segments: &[] }, cx);
1688                    register_res(cx, trait_.res);
1689                    let self_def_id = res.opt_def_id();
1690                    let should_fully_qualify =
1691                        should_fully_qualify_path(self_def_id, &trait_, &self_type);
1692
1693                    (Some(trait_), should_fully_qualify)
1694                }
1695                ty::Alias(ty::Inherent, _) => (None, false),
1696                // Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
1697                ty::Error(_) => return Type::Infer,
1698                _ => bug!("clean: expected associated type, found `{ty:?}`"),
1699            };
1700
1701            Type::QPath(Box::new(QPathData {
1702                assoc: clean_path_segment(segment, cx),
1703                should_fully_qualify,
1704                self_type,
1705                trait_,
1706            }))
1707        }
1708        hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1709    }
1710}
1711
1712fn maybe_expand_private_type_alias<'tcx>(
1713    cx: &mut DocContext<'tcx>,
1714    path: &hir::Path<'tcx>,
1715) -> Option<Type> {
1716    let Res::Def(DefKind::TyAlias, def_id) = path.res else { return None };
1717    // Substitute private type aliases
1718    let def_id = def_id.as_local()?;
1719    let alias = if !cx.cache.effective_visibilities.is_exported(cx.tcx, def_id.to_def_id())
1720        && !cx.current_type_aliases.contains_key(&def_id.to_def_id())
1721    {
1722        &cx.tcx.hir_expect_item(def_id).kind
1723    } else {
1724        return None;
1725    };
1726    let hir::ItemKind::TyAlias(_, generics, ty) = alias else { return None };
1727
1728    let final_seg = &path.segments.last().expect("segments were empty");
1729    let mut args = DefIdMap::default();
1730    let generic_args = final_seg.args();
1731
1732    let mut indices: hir::GenericParamCount = Default::default();
1733    for param in generics.params.iter() {
1734        match param.kind {
1735            hir::GenericParamKind::Lifetime { .. } => {
1736                let mut j = 0;
1737                let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1738                    hir::GenericArg::Lifetime(lt) => {
1739                        if indices.lifetimes == j {
1740                            return Some(lt);
1741                        }
1742                        j += 1;
1743                        None
1744                    }
1745                    _ => None,
1746                });
1747                if let Some(lt) = lifetime {
1748                    let lt = if !lt.is_anonymous() {
1749                        clean_lifetime(lt, cx)
1750                    } else {
1751                        Lifetime::elided()
1752                    };
1753                    args.insert(param.def_id.to_def_id(), GenericArg::Lifetime(lt));
1754                }
1755                indices.lifetimes += 1;
1756            }
1757            hir::GenericParamKind::Type { ref default, .. } => {
1758                let mut j = 0;
1759                let type_ = generic_args.args.iter().find_map(|arg| match arg {
1760                    hir::GenericArg::Type(ty) => {
1761                        if indices.types == j {
1762                            return Some(ty.as_unambig_ty());
1763                        }
1764                        j += 1;
1765                        None
1766                    }
1767                    _ => None,
1768                });
1769                if let Some(ty) = type_.or(*default) {
1770                    args.insert(param.def_id.to_def_id(), GenericArg::Type(clean_ty(ty, cx)));
1771                }
1772                indices.types += 1;
1773            }
1774            // FIXME(#82852): Instantiate const parameters.
1775            hir::GenericParamKind::Const { .. } => {}
1776        }
1777    }
1778
1779    Some(cx.enter_alias(args, def_id.to_def_id(), |cx| {
1780        cx.with_param_env(def_id.to_def_id(), |cx| clean_ty(ty, cx))
1781    }))
1782}
1783
1784pub(crate) fn clean_ty<'tcx>(ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1785    use rustc_hir::*;
1786
1787    match ty.kind {
1788        TyKind::Never => Primitive(PrimitiveType::Never),
1789        TyKind::Ptr(ref m) => RawPointer(m.mutbl, Box::new(clean_ty(m.ty, cx))),
1790        TyKind::Ref(l, ref m) => {
1791            let lifetime = if l.is_anonymous() { None } else { Some(clean_lifetime(l, cx)) };
1792            BorrowedRef { lifetime, mutability: m.mutbl, type_: Box::new(clean_ty(m.ty, cx)) }
1793        }
1794        TyKind::Slice(ty) => Slice(Box::new(clean_ty(ty, cx))),
1795        TyKind::Pat(ty, pat) => Type::Pat(Box::new(clean_ty(ty, cx)), format!("{pat:?}").into()),
1796        TyKind::Array(ty, const_arg) => {
1797            // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1798            // as we currently do not supply the parent generics to anonymous constants
1799            // but do allow `ConstKind::Param`.
1800            //
1801            // `const_eval_poly` tries to first substitute generic parameters which
1802            // results in an ICE while manually constructing the constant and using `eval`
1803            // does nothing for `ConstKind::Param`.
1804            let length = match const_arg.kind {
1805                hir::ConstArgKind::Infer(..) => "_".to_string(),
1806                hir::ConstArgKind::Anon(hir::AnonConst { def_id, .. }) => {
1807                    let ct = lower_const_arg_for_rustdoc(cx.tcx, const_arg, FeedConstTy::No);
1808                    let typing_env = ty::TypingEnv::post_analysis(cx.tcx, *def_id);
1809                    let ct = cx.tcx.normalize_erasing_regions(typing_env, ct);
1810                    print_const(cx, ct)
1811                }
1812                hir::ConstArgKind::Path(..) => {
1813                    let ct = lower_const_arg_for_rustdoc(cx.tcx, const_arg, FeedConstTy::No);
1814                    print_const(cx, ct)
1815                }
1816            };
1817            Array(Box::new(clean_ty(ty, cx)), length.into())
1818        }
1819        TyKind::Tup(tys) => Tuple(tys.iter().map(|ty| clean_ty(ty, cx)).collect()),
1820        TyKind::OpaqueDef(ty) => {
1821            ImplTrait(ty.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect())
1822        }
1823        TyKind::Path(_) => clean_qpath(ty, cx),
1824        TyKind::TraitObject(bounds, lifetime) => {
1825            let bounds = bounds.iter().map(|bound| clean_poly_trait_ref(bound, cx)).collect();
1826            let lifetime = if !lifetime.is_elided() {
1827                Some(clean_lifetime(lifetime.pointer(), cx))
1828            } else {
1829                None
1830            };
1831            DynTrait(bounds, lifetime)
1832        }
1833        TyKind::FnPtr(barefn) => BareFunction(Box::new(clean_bare_fn_ty(barefn, cx))),
1834        TyKind::UnsafeBinder(unsafe_binder_ty) => {
1835            UnsafeBinder(Box::new(clean_unsafe_binder_ty(unsafe_binder_ty, cx)))
1836        }
1837        // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
1838        TyKind::Infer(())
1839        | TyKind::Err(_)
1840        | TyKind::Typeof(..)
1841        | TyKind::InferDelegation(..)
1842        | TyKind::TraitAscription(_) => Infer,
1843    }
1844}
1845
1846/// Returns `None` if the type could not be normalized
1847fn normalize<'tcx>(
1848    cx: &DocContext<'tcx>,
1849    ty: ty::Binder<'tcx, Ty<'tcx>>,
1850) -> Option<ty::Binder<'tcx, Ty<'tcx>>> {
1851    // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1852    if !cx.tcx.sess.opts.unstable_opts.normalize_docs {
1853        return None;
1854    }
1855
1856    use rustc_middle::traits::ObligationCause;
1857    use rustc_trait_selection::infer::TyCtxtInferExt;
1858    use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
1859
1860    // Try to normalize `<X as Y>::T` to a type
1861    let infcx = cx.tcx.infer_ctxt().build(TypingMode::non_body_analysis());
1862    let normalized = infcx
1863        .at(&ObligationCause::dummy(), cx.param_env)
1864        .query_normalize(ty)
1865        .map(|resolved| infcx.resolve_vars_if_possible(resolved.value));
1866    match normalized {
1867        Ok(normalized_value) => {
1868            debug!("normalized {ty:?} to {normalized_value:?}");
1869            Some(normalized_value)
1870        }
1871        Err(err) => {
1872            debug!("failed to normalize {ty:?}: {err:?}");
1873            None
1874        }
1875    }
1876}
1877
1878fn clean_trait_object_lifetime_bound<'tcx>(
1879    region: ty::Region<'tcx>,
1880    container: Option<ContainerTy<'_, 'tcx>>,
1881    preds: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
1882    tcx: TyCtxt<'tcx>,
1883) -> Option<Lifetime> {
1884    if can_elide_trait_object_lifetime_bound(region, container, preds, tcx) {
1885        return None;
1886    }
1887
1888    // Since there is a semantic difference between an implicitly elided (i.e. "defaulted") object
1889    // lifetime and an explicitly elided object lifetime (`'_`), we intentionally don't hide the
1890    // latter contrary to `clean_middle_region`.
1891    match region.kind() {
1892        ty::ReStatic => Some(Lifetime::statik()),
1893        ty::ReEarlyParam(region) => Some(Lifetime(region.name)),
1894        ty::ReBound(_, ty::BoundRegion { kind: ty::BoundRegionKind::Named(def_id), .. }) => {
1895            Some(Lifetime(tcx.item_name(def_id)))
1896        }
1897        ty::ReBound(..)
1898        | ty::ReLateParam(_)
1899        | ty::ReVar(_)
1900        | ty::RePlaceholder(_)
1901        | ty::ReErased
1902        | ty::ReError(_) => None,
1903    }
1904}
1905
1906fn can_elide_trait_object_lifetime_bound<'tcx>(
1907    region: ty::Region<'tcx>,
1908    container: Option<ContainerTy<'_, 'tcx>>,
1909    preds: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
1910    tcx: TyCtxt<'tcx>,
1911) -> bool {
1912    // Below we quote extracts from https://doc.rust-lang.org/stable/reference/lifetime-elision.html#default-trait-object-lifetimes
1913
1914    // > If the trait object is used as a type argument of a generic type then the containing type is
1915    // > first used to try to infer a bound.
1916    let default = container
1917        .map_or(ObjectLifetimeDefault::Empty, |container| container.object_lifetime_default(tcx));
1918
1919    // > If there is a unique bound from the containing type then that is the default
1920    // If there is a default object lifetime and the given region is lexically equal to it, elide it.
1921    match default {
1922        ObjectLifetimeDefault::Static => return region.kind() == ty::ReStatic,
1923        // FIXME(fmease): Don't compare lexically but respect de Bruijn indices etc. to handle shadowing correctly.
1924        ObjectLifetimeDefault::Arg(default) => {
1925            return region.get_name(tcx) == default.get_name(tcx);
1926        }
1927        // > If there is more than one bound from the containing type then an explicit bound must be specified
1928        // Due to ambiguity there is no default trait-object lifetime and thus elision is impossible.
1929        // Don't elide the lifetime.
1930        ObjectLifetimeDefault::Ambiguous => return false,
1931        // There is no meaningful bound. Further processing is needed...
1932        ObjectLifetimeDefault::Empty => {}
1933    }
1934
1935    // > If neither of those rules apply, then the bounds on the trait are used:
1936    match *object_region_bounds(tcx, preds) {
1937        // > If the trait has no lifetime bounds, then the lifetime is inferred in expressions
1938        // > and is 'static outside of expressions.
1939        // FIXME: If we are in an expression context (i.e. fn bodies and const exprs) then the default is
1940        // `'_` and not `'static`. Only if we are in a non-expression one, the default is `'static`.
1941        // Note however that at the time of this writing it should be fine to disregard this subtlety
1942        // as we neither render const exprs faithfully anyway (hiding them in some places or using `_` instead)
1943        // nor show the contents of fn bodies.
1944        [] => region.kind() == ty::ReStatic,
1945        // > If the trait is defined with a single lifetime bound then that bound is used.
1946        // > If 'static is used for any lifetime bound then 'static is used.
1947        // FIXME(fmease): Don't compare lexically but respect de Bruijn indices etc. to handle shadowing correctly.
1948        [object_region] => object_region.get_name(tcx) == region.get_name(tcx),
1949        // There are several distinct trait regions and none are `'static`.
1950        // Due to ambiguity there is no default trait-object lifetime and thus elision is impossible.
1951        // Don't elide the lifetime.
1952        _ => false,
1953    }
1954}
1955
1956#[derive(Debug)]
1957pub(crate) enum ContainerTy<'a, 'tcx> {
1958    Ref(ty::Region<'tcx>),
1959    Regular {
1960        ty: DefId,
1961        /// The arguments *have* to contain an arg for the self type if the corresponding generics
1962        /// contain a self type.
1963        args: ty::Binder<'tcx, &'a [ty::GenericArg<'tcx>]>,
1964        arg: usize,
1965    },
1966}
1967
1968impl<'tcx> ContainerTy<'_, 'tcx> {
1969    fn object_lifetime_default(self, tcx: TyCtxt<'tcx>) -> ObjectLifetimeDefault<'tcx> {
1970        match self {
1971            Self::Ref(region) => ObjectLifetimeDefault::Arg(region),
1972            Self::Regular { ty: container, args, arg: index } => {
1973                let (DefKind::Struct
1974                | DefKind::Union
1975                | DefKind::Enum
1976                | DefKind::TyAlias
1977                | DefKind::Trait) = tcx.def_kind(container)
1978                else {
1979                    return ObjectLifetimeDefault::Empty;
1980                };
1981
1982                let generics = tcx.generics_of(container);
1983                debug_assert_eq!(generics.parent_count, 0);
1984
1985                let param = generics.own_params[index].def_id;
1986                let default = tcx.object_lifetime_default(param);
1987                match default {
1988                    rbv::ObjectLifetimeDefault::Param(lifetime) => {
1989                        // The index is relative to the parent generics but since we don't have any,
1990                        // we don't need to translate it.
1991                        let index = generics.param_def_id_to_index[&lifetime];
1992                        let arg = args.skip_binder()[index as usize].expect_region();
1993                        ObjectLifetimeDefault::Arg(arg)
1994                    }
1995                    rbv::ObjectLifetimeDefault::Empty => ObjectLifetimeDefault::Empty,
1996                    rbv::ObjectLifetimeDefault::Static => ObjectLifetimeDefault::Static,
1997                    rbv::ObjectLifetimeDefault::Ambiguous => ObjectLifetimeDefault::Ambiguous,
1998                }
1999            }
2000        }
2001    }
2002}
2003
2004#[derive(Debug, Clone, Copy)]
2005pub(crate) enum ObjectLifetimeDefault<'tcx> {
2006    Empty,
2007    Static,
2008    Ambiguous,
2009    Arg(ty::Region<'tcx>),
2010}
2011
2012#[instrument(level = "trace", skip(cx), ret)]
2013pub(crate) fn clean_middle_ty<'tcx>(
2014    bound_ty: ty::Binder<'tcx, Ty<'tcx>>,
2015    cx: &mut DocContext<'tcx>,
2016    parent_def_id: Option<DefId>,
2017    container: Option<ContainerTy<'_, 'tcx>>,
2018) -> Type {
2019    let bound_ty = normalize(cx, bound_ty).unwrap_or(bound_ty);
2020    match *bound_ty.skip_binder().kind() {
2021        ty::Never => Primitive(PrimitiveType::Never),
2022        ty::Bool => Primitive(PrimitiveType::Bool),
2023        ty::Char => Primitive(PrimitiveType::Char),
2024        ty::Int(int_ty) => Primitive(int_ty.into()),
2025        ty::Uint(uint_ty) => Primitive(uint_ty.into()),
2026        ty::Float(float_ty) => Primitive(float_ty.into()),
2027        ty::Str => Primitive(PrimitiveType::Str),
2028        ty::Slice(ty) => Slice(Box::new(clean_middle_ty(bound_ty.rebind(ty), cx, None, None))),
2029        ty::Pat(ty, pat) => Type::Pat(
2030            Box::new(clean_middle_ty(bound_ty.rebind(ty), cx, None, None)),
2031            format!("{pat:?}").into_boxed_str(),
2032        ),
2033        ty::Array(ty, n) => {
2034            let n = cx.tcx.normalize_erasing_regions(cx.typing_env(), n);
2035            let n = print_const(cx, n);
2036            Array(Box::new(clean_middle_ty(bound_ty.rebind(ty), cx, None, None)), n.into())
2037        }
2038        ty::RawPtr(ty, mutbl) => {
2039            RawPointer(mutbl, Box::new(clean_middle_ty(bound_ty.rebind(ty), cx, None, None)))
2040        }
2041        ty::Ref(r, ty, mutbl) => BorrowedRef {
2042            lifetime: clean_middle_region(r, cx),
2043            mutability: mutbl,
2044            type_: Box::new(clean_middle_ty(
2045                bound_ty.rebind(ty),
2046                cx,
2047                None,
2048                Some(ContainerTy::Ref(r)),
2049            )),
2050        },
2051        ty::FnDef(..) | ty::FnPtr(..) => {
2052            // FIXME: should we merge the outer and inner binders somehow?
2053            let sig = bound_ty.skip_binder().fn_sig(cx.tcx);
2054            let decl = clean_poly_fn_sig(cx, None, sig);
2055            let generic_params = clean_bound_vars(sig.bound_vars(), cx);
2056
2057            BareFunction(Box::new(BareFunctionDecl {
2058                safety: sig.safety(),
2059                generic_params,
2060                decl,
2061                abi: sig.abi(),
2062            }))
2063        }
2064        ty::UnsafeBinder(inner) => {
2065            let generic_params = clean_bound_vars(inner.bound_vars(), cx);
2066            let ty = clean_middle_ty(inner.into(), cx, None, None);
2067            UnsafeBinder(Box::new(UnsafeBinderTy { generic_params, ty }))
2068        }
2069        ty::Adt(def, args) => {
2070            let did = def.did();
2071            let kind = match def.adt_kind() {
2072                AdtKind::Struct => ItemType::Struct,
2073                AdtKind::Union => ItemType::Union,
2074                AdtKind::Enum => ItemType::Enum,
2075            };
2076            inline::record_extern_fqn(cx, did, kind);
2077            let path = clean_middle_path(cx, did, false, ThinVec::new(), bound_ty.rebind(args));
2078            Type::Path { path }
2079        }
2080        ty::Foreign(did) => {
2081            inline::record_extern_fqn(cx, did, ItemType::ForeignType);
2082            let path = clean_middle_path(
2083                cx,
2084                did,
2085                false,
2086                ThinVec::new(),
2087                ty::Binder::dummy(ty::GenericArgs::empty()),
2088            );
2089            Type::Path { path }
2090        }
2091        ty::Dynamic(obj, reg, _) => {
2092            // HACK: pick the first `did` as the `did` of the trait object. Someone
2093            // might want to implement "native" support for marker-trait-only
2094            // trait objects.
2095            let mut dids = obj.auto_traits();
2096            let did = obj
2097                .principal_def_id()
2098                .or_else(|| dids.next())
2099                .unwrap_or_else(|| panic!("found trait object `{bound_ty:?}` with no traits?"));
2100            let args = match obj.principal() {
2101                Some(principal) => principal.map_bound(|p| p.args),
2102                // marker traits have no args.
2103                _ => ty::Binder::dummy(ty::GenericArgs::empty()),
2104            };
2105
2106            inline::record_extern_fqn(cx, did, ItemType::Trait);
2107
2108            let lifetime = clean_trait_object_lifetime_bound(reg, container, obj, cx.tcx);
2109
2110            let mut bounds = dids
2111                .map(|did| {
2112                    let empty = ty::Binder::dummy(ty::GenericArgs::empty());
2113                    let path = clean_middle_path(cx, did, false, ThinVec::new(), empty);
2114                    inline::record_extern_fqn(cx, did, ItemType::Trait);
2115                    PolyTrait { trait_: path, generic_params: Vec::new() }
2116                })
2117                .collect::<Vec<_>>();
2118
2119            let constraints = obj
2120                .projection_bounds()
2121                .map(|pb| AssocItemConstraint {
2122                    assoc: projection_to_path_segment(
2123                        pb.map_bound(|pb| {
2124                            pb.with_self_ty(cx.tcx, cx.tcx.types.trait_object_dummy_self)
2125                                .projection_term
2126                        }),
2127                        cx,
2128                    ),
2129                    kind: AssocItemConstraintKind::Equality {
2130                        term: clean_middle_term(pb.map_bound(|pb| pb.term), cx),
2131                    },
2132                })
2133                .collect();
2134
2135            let late_bound_regions: FxIndexSet<_> = obj
2136                .iter()
2137                .flat_map(|pred| pred.bound_vars())
2138                .filter_map(|var| match var {
2139                    ty::BoundVariableKind::Region(ty::BoundRegionKind::Named(def_id)) => {
2140                        let name = cx.tcx.item_name(def_id);
2141                        if name != kw::UnderscoreLifetime {
2142                            Some(GenericParamDef::lifetime(def_id, name))
2143                        } else {
2144                            None
2145                        }
2146                    }
2147                    _ => None,
2148                })
2149                .collect();
2150            let late_bound_regions = late_bound_regions.into_iter().collect();
2151
2152            let path = clean_middle_path(cx, did, false, constraints, args);
2153            bounds.insert(0, PolyTrait { trait_: path, generic_params: late_bound_regions });
2154
2155            DynTrait(bounds, lifetime)
2156        }
2157        ty::Tuple(t) => {
2158            Tuple(t.iter().map(|t| clean_middle_ty(bound_ty.rebind(t), cx, None, None)).collect())
2159        }
2160
2161        ty::Alias(ty::Projection, alias_ty @ ty::AliasTy { def_id, args, .. }) => {
2162            if cx.tcx.is_impl_trait_in_trait(def_id) {
2163                clean_middle_opaque_bounds(cx, def_id, args)
2164            } else {
2165                Type::QPath(Box::new(clean_projection(
2166                    bound_ty.rebind(alias_ty.into()),
2167                    cx,
2168                    parent_def_id,
2169                )))
2170            }
2171        }
2172
2173        ty::Alias(ty::Inherent, alias_ty @ ty::AliasTy { def_id, .. }) => {
2174            let alias_ty = bound_ty.rebind(alias_ty);
2175            let self_type = clean_middle_ty(alias_ty.map_bound(|ty| ty.self_ty()), cx, None, None);
2176
2177            Type::QPath(Box::new(QPathData {
2178                assoc: PathSegment {
2179                    name: cx.tcx.item_name(def_id),
2180                    args: GenericArgs::AngleBracketed {
2181                        args: clean_middle_generic_args(
2182                            cx,
2183                            alias_ty.map_bound(|ty| ty.args.as_slice()),
2184                            true,
2185                            def_id,
2186                        ),
2187                        constraints: Default::default(),
2188                    },
2189                },
2190                should_fully_qualify: false,
2191                self_type,
2192                trait_: None,
2193            }))
2194        }
2195
2196        ty::Alias(ty::Free, ty::AliasTy { def_id, args, .. }) => {
2197            if cx.tcx.features().lazy_type_alias() {
2198                // Free type alias `data` represents the `type X` in `type X = Y`. If we need `Y`,
2199                // we need to use `type_of`.
2200                let path =
2201                    clean_middle_path(cx, def_id, false, ThinVec::new(), bound_ty.rebind(args));
2202                Type::Path { path }
2203            } else {
2204                let ty = cx.tcx.type_of(def_id).instantiate(cx.tcx, args);
2205                clean_middle_ty(bound_ty.rebind(ty), cx, None, None)
2206            }
2207        }
2208
2209        ty::Param(ref p) => {
2210            if let Some(bounds) = cx.impl_trait_bounds.remove(&p.index.into()) {
2211                ImplTrait(bounds)
2212            } else if p.name == kw::SelfUpper {
2213                SelfTy
2214            } else {
2215                Generic(p.name)
2216            }
2217        }
2218
2219        ty::Bound(_, ref ty) => match ty.kind {
2220            ty::BoundTyKind::Param(def_id) => Generic(cx.tcx.item_name(def_id)),
2221            ty::BoundTyKind::Anon => panic!("unexpected anonymous bound type variable"),
2222        },
2223
2224        ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
2225            // If it's already in the same alias, don't get an infinite loop.
2226            if cx.current_type_aliases.contains_key(&def_id) {
2227                let path =
2228                    clean_middle_path(cx, def_id, false, ThinVec::new(), bound_ty.rebind(args));
2229                Type::Path { path }
2230            } else {
2231                *cx.current_type_aliases.entry(def_id).or_insert(0) += 1;
2232                // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
2233                // by looking up the bounds associated with the def_id.
2234                let ty = clean_middle_opaque_bounds(cx, def_id, args);
2235                if let Some(count) = cx.current_type_aliases.get_mut(&def_id) {
2236                    *count -= 1;
2237                    if *count == 0 {
2238                        cx.current_type_aliases.remove(&def_id);
2239                    }
2240                }
2241                ty
2242            }
2243        }
2244
2245        ty::Closure(..) => panic!("Closure"),
2246        ty::CoroutineClosure(..) => panic!("CoroutineClosure"),
2247        ty::Coroutine(..) => panic!("Coroutine"),
2248        ty::Placeholder(..) => panic!("Placeholder"),
2249        ty::CoroutineWitness(..) => panic!("CoroutineWitness"),
2250        ty::Infer(..) => panic!("Infer"),
2251
2252        ty::Error(_) => FatalError.raise(),
2253    }
2254}
2255
2256fn clean_middle_opaque_bounds<'tcx>(
2257    cx: &mut DocContext<'tcx>,
2258    impl_trait_def_id: DefId,
2259    args: ty::GenericArgsRef<'tcx>,
2260) -> Type {
2261    let mut has_sized = false;
2262
2263    let bounds: Vec<_> = cx
2264        .tcx
2265        .explicit_item_bounds(impl_trait_def_id)
2266        .iter_instantiated_copied(cx.tcx, args)
2267        .collect();
2268
2269    let mut bounds = bounds
2270        .iter()
2271        .filter_map(|(bound, _)| {
2272            let bound_predicate = bound.kind();
2273            let trait_ref = match bound_predicate.skip_binder() {
2274                ty::ClauseKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
2275                ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
2276                    return clean_middle_region(reg, cx).map(GenericBound::Outlives);
2277                }
2278                _ => return None,
2279            };
2280
2281            // FIXME(sized-hierarchy): Always skip `MetaSized` bounds so that only `?Sized`
2282            // is shown and none of the new sizedness traits leak into documentation.
2283            if cx.tcx.is_lang_item(trait_ref.def_id(), LangItem::MetaSized) {
2284                return None;
2285            }
2286
2287            if let Some(sized) = cx.tcx.lang_items().sized_trait()
2288                && trait_ref.def_id() == sized
2289            {
2290                has_sized = true;
2291                return None;
2292            }
2293
2294            let bindings: ThinVec<_> = bounds
2295                .iter()
2296                .filter_map(|(bound, _)| {
2297                    let bound = bound.kind();
2298                    if let ty::ClauseKind::Projection(proj_pred) = bound.skip_binder()
2299                        && proj_pred.projection_term.trait_ref(cx.tcx) == trait_ref.skip_binder()
2300                    {
2301                        return Some(AssocItemConstraint {
2302                            assoc: projection_to_path_segment(
2303                                bound.rebind(proj_pred.projection_term),
2304                                cx,
2305                            ),
2306                            kind: AssocItemConstraintKind::Equality {
2307                                term: clean_middle_term(bound.rebind(proj_pred.term), cx),
2308                            },
2309                        });
2310                    }
2311                    None
2312                })
2313                .collect();
2314
2315            Some(clean_poly_trait_ref_with_constraints(cx, trait_ref, bindings))
2316        })
2317        .collect::<Vec<_>>();
2318
2319    if !has_sized {
2320        bounds.push(GenericBound::maybe_sized(cx));
2321    }
2322
2323    // Move trait bounds to the front.
2324    bounds.sort_by_key(|b| !b.is_trait_bound());
2325
2326    // Add back a `Sized` bound if there are no *trait* bounds remaining (incl. `?Sized`).
2327    // Since all potential trait bounds are at the front we can just check the first bound.
2328    if bounds.first().is_none_or(|b| !b.is_trait_bound()) {
2329        bounds.insert(0, GenericBound::sized(cx));
2330    }
2331
2332    if let Some(args) = cx.tcx.rendered_precise_capturing_args(impl_trait_def_id) {
2333        bounds.push(GenericBound::Use(
2334            args.iter()
2335                .map(|arg| match arg {
2336                    hir::PreciseCapturingArgKind::Lifetime(lt) => {
2337                        PreciseCapturingArg::Lifetime(Lifetime(*lt))
2338                    }
2339                    hir::PreciseCapturingArgKind::Param(param) => {
2340                        PreciseCapturingArg::Param(*param)
2341                    }
2342                })
2343                .collect(),
2344        ));
2345    }
2346
2347    ImplTrait(bounds)
2348}
2349
2350pub(crate) fn clean_field<'tcx>(field: &hir::FieldDef<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
2351    clean_field_with_def_id(field.def_id.to_def_id(), field.ident.name, clean_ty(field.ty, cx), cx)
2352}
2353
2354pub(crate) fn clean_middle_field(field: &ty::FieldDef, cx: &mut DocContext<'_>) -> Item {
2355    clean_field_with_def_id(
2356        field.did,
2357        field.name,
2358        clean_middle_ty(
2359            ty::Binder::dummy(cx.tcx.type_of(field.did).instantiate_identity()),
2360            cx,
2361            Some(field.did),
2362            None,
2363        ),
2364        cx,
2365    )
2366}
2367
2368pub(crate) fn clean_field_with_def_id(
2369    def_id: DefId,
2370    name: Symbol,
2371    ty: Type,
2372    cx: &mut DocContext<'_>,
2373) -> Item {
2374    Item::from_def_id_and_parts(def_id, Some(name), StructFieldItem(ty), cx)
2375}
2376
2377pub(crate) fn clean_variant_def(variant: &ty::VariantDef, cx: &mut DocContext<'_>) -> Item {
2378    let discriminant = match variant.discr {
2379        ty::VariantDiscr::Explicit(def_id) => Some(Discriminant { expr: None, value: def_id }),
2380        ty::VariantDiscr::Relative(_) => None,
2381    };
2382
2383    let kind = match variant.ctor_kind() {
2384        Some(CtorKind::Const) => VariantKind::CLike,
2385        Some(CtorKind::Fn) => VariantKind::Tuple(
2386            variant.fields.iter().map(|field| clean_middle_field(field, cx)).collect(),
2387        ),
2388        None => VariantKind::Struct(VariantStruct {
2389            fields: variant.fields.iter().map(|field| clean_middle_field(field, cx)).collect(),
2390        }),
2391    };
2392
2393    Item::from_def_id_and_parts(
2394        variant.def_id,
2395        Some(variant.name),
2396        VariantItem(Variant { kind, discriminant }),
2397        cx,
2398    )
2399}
2400
2401pub(crate) fn clean_variant_def_with_args<'tcx>(
2402    variant: &ty::VariantDef,
2403    args: &GenericArgsRef<'tcx>,
2404    cx: &mut DocContext<'tcx>,
2405) -> Item {
2406    let discriminant = match variant.discr {
2407        ty::VariantDiscr::Explicit(def_id) => Some(Discriminant { expr: None, value: def_id }),
2408        ty::VariantDiscr::Relative(_) => None,
2409    };
2410
2411    use rustc_middle::traits::ObligationCause;
2412    use rustc_trait_selection::infer::TyCtxtInferExt;
2413    use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
2414
2415    let infcx = cx.tcx.infer_ctxt().build(TypingMode::non_body_analysis());
2416    let kind = match variant.ctor_kind() {
2417        Some(CtorKind::Const) => VariantKind::CLike,
2418        Some(CtorKind::Fn) => VariantKind::Tuple(
2419            variant
2420                .fields
2421                .iter()
2422                .map(|field| {
2423                    let ty = cx.tcx.type_of(field.did).instantiate(cx.tcx, args);
2424
2425                    // normalize the type to only show concrete types
2426                    // note: we do not use try_normalize_erasing_regions since we
2427                    // do care about showing the regions
2428                    let ty = infcx
2429                        .at(&ObligationCause::dummy(), cx.param_env)
2430                        .query_normalize(ty)
2431                        .map(|normalized| normalized.value)
2432                        .unwrap_or(ty);
2433
2434                    clean_field_with_def_id(
2435                        field.did,
2436                        field.name,
2437                        clean_middle_ty(ty::Binder::dummy(ty), cx, Some(field.did), None),
2438                        cx,
2439                    )
2440                })
2441                .collect(),
2442        ),
2443        None => VariantKind::Struct(VariantStruct {
2444            fields: variant
2445                .fields
2446                .iter()
2447                .map(|field| {
2448                    let ty = cx.tcx.type_of(field.did).instantiate(cx.tcx, args);
2449
2450                    // normalize the type to only show concrete types
2451                    // note: we do not use try_normalize_erasing_regions since we
2452                    // do care about showing the regions
2453                    let ty = infcx
2454                        .at(&ObligationCause::dummy(), cx.param_env)
2455                        .query_normalize(ty)
2456                        .map(|normalized| normalized.value)
2457                        .unwrap_or(ty);
2458
2459                    clean_field_with_def_id(
2460                        field.did,
2461                        field.name,
2462                        clean_middle_ty(ty::Binder::dummy(ty), cx, Some(field.did), None),
2463                        cx,
2464                    )
2465                })
2466                .collect(),
2467        }),
2468    };
2469
2470    Item::from_def_id_and_parts(
2471        variant.def_id,
2472        Some(variant.name),
2473        VariantItem(Variant { kind, discriminant }),
2474        cx,
2475    )
2476}
2477
2478fn clean_variant_data<'tcx>(
2479    variant: &hir::VariantData<'tcx>,
2480    disr_expr: &Option<&hir::AnonConst>,
2481    cx: &mut DocContext<'tcx>,
2482) -> Variant {
2483    let discriminant = disr_expr
2484        .map(|disr| Discriminant { expr: Some(disr.body), value: disr.def_id.to_def_id() });
2485
2486    let kind = match variant {
2487        hir::VariantData::Struct { fields, .. } => VariantKind::Struct(VariantStruct {
2488            fields: fields.iter().map(|x| clean_field(x, cx)).collect(),
2489        }),
2490        hir::VariantData::Tuple(..) => {
2491            VariantKind::Tuple(variant.fields().iter().map(|x| clean_field(x, cx)).collect())
2492        }
2493        hir::VariantData::Unit(..) => VariantKind::CLike,
2494    };
2495
2496    Variant { discriminant, kind }
2497}
2498
2499fn clean_path<'tcx>(path: &hir::Path<'tcx>, cx: &mut DocContext<'tcx>) -> Path {
2500    Path {
2501        res: path.res,
2502        segments: path.segments.iter().map(|x| clean_path_segment(x, cx)).collect(),
2503    }
2504}
2505
2506fn clean_generic_args<'tcx>(
2507    generic_args: &hir::GenericArgs<'tcx>,
2508    cx: &mut DocContext<'tcx>,
2509) -> GenericArgs {
2510    match generic_args.parenthesized {
2511        hir::GenericArgsParentheses::No => {
2512            let args = generic_args
2513                .args
2514                .iter()
2515                .map(|arg| match arg {
2516                    hir::GenericArg::Lifetime(lt) if !lt.is_anonymous() => {
2517                        GenericArg::Lifetime(clean_lifetime(lt, cx))
2518                    }
2519                    hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
2520                    hir::GenericArg::Type(ty) => GenericArg::Type(clean_ty(ty.as_unambig_ty(), cx)),
2521                    hir::GenericArg::Const(ct) => {
2522                        GenericArg::Const(Box::new(clean_const(ct.as_unambig_ct(), cx)))
2523                    }
2524                    hir::GenericArg::Infer(_inf) => GenericArg::Infer,
2525                })
2526                .collect();
2527            let constraints = generic_args
2528                .constraints
2529                .iter()
2530                .map(|c| clean_assoc_item_constraint(c, cx))
2531                .collect::<ThinVec<_>>();
2532            GenericArgs::AngleBracketed { args, constraints }
2533        }
2534        hir::GenericArgsParentheses::ParenSugar => {
2535            let Some((inputs, output)) = generic_args.paren_sugar_inputs_output() else {
2536                bug!();
2537            };
2538            let inputs = inputs.iter().map(|x| clean_ty(x, cx)).collect();
2539            let output = match output.kind {
2540                hir::TyKind::Tup(&[]) => None,
2541                _ => Some(Box::new(clean_ty(output, cx))),
2542            };
2543            GenericArgs::Parenthesized { inputs, output }
2544        }
2545        hir::GenericArgsParentheses::ReturnTypeNotation => GenericArgs::ReturnTypeNotation,
2546    }
2547}
2548
2549fn clean_path_segment<'tcx>(
2550    path: &hir::PathSegment<'tcx>,
2551    cx: &mut DocContext<'tcx>,
2552) -> PathSegment {
2553    PathSegment { name: path.ident.name, args: clean_generic_args(path.args(), cx) }
2554}
2555
2556fn clean_bare_fn_ty<'tcx>(
2557    bare_fn: &hir::FnPtrTy<'tcx>,
2558    cx: &mut DocContext<'tcx>,
2559) -> BareFunctionDecl {
2560    let (generic_params, decl) = enter_impl_trait(cx, |cx| {
2561        // NOTE: Generics must be cleaned before params.
2562        let generic_params = bare_fn
2563            .generic_params
2564            .iter()
2565            .filter(|p| !is_elided_lifetime(p))
2566            .map(|x| clean_generic_param(cx, None, x))
2567            .collect();
2568        // Since it's more conventional stylistically, elide the name of all params called `_`
2569        // unless there's at least one interestingly named param in which case don't elide any
2570        // name since mixing named and unnamed params is less legible.
2571        let filter = |ident: Option<Ident>| {
2572            ident.map(|ident| ident.name).filter(|&ident| ident != kw::Underscore)
2573        };
2574        let fallback =
2575            bare_fn.param_idents.iter().copied().find_map(filter).map(|_| kw::Underscore);
2576        let params = clean_params(cx, bare_fn.decl.inputs, bare_fn.param_idents, |ident| {
2577            filter(ident).or(fallback)
2578        });
2579        let decl = clean_fn_decl_with_params(cx, bare_fn.decl, None, params);
2580        (generic_params, decl)
2581    });
2582    BareFunctionDecl { safety: bare_fn.safety, abi: bare_fn.abi, decl, generic_params }
2583}
2584
2585fn clean_unsafe_binder_ty<'tcx>(
2586    unsafe_binder_ty: &hir::UnsafeBinderTy<'tcx>,
2587    cx: &mut DocContext<'tcx>,
2588) -> UnsafeBinderTy {
2589    let generic_params = unsafe_binder_ty
2590        .generic_params
2591        .iter()
2592        .filter(|p| !is_elided_lifetime(p))
2593        .map(|x| clean_generic_param(cx, None, x))
2594        .collect();
2595    let ty = clean_ty(unsafe_binder_ty.inner_ty, cx);
2596    UnsafeBinderTy { generic_params, ty }
2597}
2598
2599pub(crate) fn reexport_chain(
2600    tcx: TyCtxt<'_>,
2601    import_def_id: LocalDefId,
2602    target_def_id: DefId,
2603) -> &[Reexport] {
2604    for child in tcx.module_children_local(tcx.local_parent(import_def_id)) {
2605        if child.res.opt_def_id() == Some(target_def_id)
2606            && child.reexport_chain.first().and_then(|r| r.id()) == Some(import_def_id.to_def_id())
2607        {
2608            return &child.reexport_chain;
2609        }
2610    }
2611    &[]
2612}
2613
2614/// Collect attributes from the whole import chain.
2615fn get_all_import_attributes<'hir>(
2616    cx: &mut DocContext<'hir>,
2617    import_def_id: LocalDefId,
2618    target_def_id: DefId,
2619    is_inline: bool,
2620) -> Vec<(Cow<'hir, hir::Attribute>, Option<DefId>)> {
2621    let mut attrs = Vec::new();
2622    let mut first = true;
2623    for def_id in reexport_chain(cx.tcx, import_def_id, target_def_id)
2624        .iter()
2625        .flat_map(|reexport| reexport.id())
2626    {
2627        let import_attrs = inline::load_attrs(cx, def_id);
2628        if first {
2629            // This is the "original" reexport so we get all its attributes without filtering them.
2630            attrs = import_attrs.iter().map(|attr| (Cow::Borrowed(attr), Some(def_id))).collect();
2631            first = false;
2632        // We don't add attributes of an intermediate re-export if it has `#[doc(hidden)]`.
2633        } else if cx.render_options.document_hidden || !cx.tcx.is_doc_hidden(def_id) {
2634            add_without_unwanted_attributes(&mut attrs, import_attrs, is_inline, Some(def_id));
2635        }
2636    }
2637    attrs
2638}
2639
2640fn filter_tokens_from_list(
2641    args_tokens: &TokenStream,
2642    should_retain: impl Fn(&TokenTree) -> bool,
2643) -> Vec<TokenTree> {
2644    let mut tokens = Vec::with_capacity(args_tokens.len());
2645    let mut skip_next_comma = false;
2646    for token in args_tokens.iter() {
2647        match token {
2648            TokenTree::Token(Token { kind: TokenKind::Comma, .. }, _) if skip_next_comma => {
2649                skip_next_comma = false;
2650            }
2651            token if should_retain(token) => {
2652                skip_next_comma = false;
2653                tokens.push(token.clone());
2654            }
2655            _ => {
2656                skip_next_comma = true;
2657            }
2658        }
2659    }
2660    tokens
2661}
2662
2663fn filter_doc_attr_ident(ident: Symbol, is_inline: bool) -> bool {
2664    if is_inline {
2665        ident == sym::hidden || ident == sym::inline || ident == sym::no_inline
2666    } else {
2667        ident == sym::cfg
2668    }
2669}
2670
2671/// Remove attributes from `normal` that should not be inherited by `use` re-export.
2672/// Before calling this function, make sure `normal` is a `#[doc]` attribute.
2673fn filter_doc_attr(args: &mut hir::AttrArgs, is_inline: bool) {
2674    match args {
2675        hir::AttrArgs::Delimited(args) => {
2676            let tokens = filter_tokens_from_list(&args.tokens, |token| {
2677                !matches!(
2678                    token,
2679                    TokenTree::Token(
2680                        Token {
2681                            kind: TokenKind::Ident(
2682                                ident,
2683                                _,
2684                            ),
2685                            ..
2686                        },
2687                        _,
2688                    ) if filter_doc_attr_ident(*ident, is_inline),
2689                )
2690            });
2691            args.tokens = TokenStream::new(tokens);
2692        }
2693        hir::AttrArgs::Empty | hir::AttrArgs::Eq { .. } => {}
2694    }
2695}
2696
2697/// When inlining items, we merge their attributes (and all the reexports attributes too) with the
2698/// final reexport. For example:
2699///
2700/// ```ignore (just an example)
2701/// #[doc(hidden, cfg(feature = "foo"))]
2702/// pub struct Foo;
2703///
2704/// #[doc(cfg(feature = "bar"))]
2705/// #[doc(hidden, no_inline)]
2706/// pub use Foo as Foo1;
2707///
2708/// #[doc(inline)]
2709/// pub use Foo2 as Bar;
2710/// ```
2711///
2712/// So `Bar` at the end will have both `cfg(feature = "...")`. However, we don't want to merge all
2713/// attributes so we filter out the following ones:
2714/// * `doc(inline)`
2715/// * `doc(no_inline)`
2716/// * `doc(hidden)`
2717fn add_without_unwanted_attributes<'hir>(
2718    attrs: &mut Vec<(Cow<'hir, hir::Attribute>, Option<DefId>)>,
2719    new_attrs: &'hir [hir::Attribute],
2720    is_inline: bool,
2721    import_parent: Option<DefId>,
2722) {
2723    for attr in new_attrs {
2724        if attr.is_doc_comment() {
2725            attrs.push((Cow::Borrowed(attr), import_parent));
2726            continue;
2727        }
2728        let mut attr = attr.clone();
2729        match attr {
2730            hir::Attribute::Unparsed(ref mut normal) if let [ident] = &*normal.path.segments => {
2731                let ident = ident.name;
2732                if ident == sym::doc {
2733                    filter_doc_attr(&mut normal.args, is_inline);
2734                    attrs.push((Cow::Owned(attr), import_parent));
2735                } else if is_inline || ident != sym::cfg_trace {
2736                    // If it's not a `cfg()` attribute, we keep it.
2737                    attrs.push((Cow::Owned(attr), import_parent));
2738                }
2739            }
2740            // FIXME: make sure to exclude `#[cfg_trace]` here when it is ported to the new parsers
2741            hir::Attribute::Parsed(..) => {
2742                attrs.push((Cow::Owned(attr), import_parent));
2743            }
2744            _ => {}
2745        }
2746    }
2747}
2748
2749fn clean_maybe_renamed_item<'tcx>(
2750    cx: &mut DocContext<'tcx>,
2751    item: &hir::Item<'tcx>,
2752    renamed: Option<Symbol>,
2753    import_ids: &[LocalDefId],
2754) -> Vec<Item> {
2755    use hir::ItemKind;
2756    fn get_name(
2757        cx: &DocContext<'_>,
2758        item: &hir::Item<'_>,
2759        renamed: Option<Symbol>,
2760    ) -> Option<Symbol> {
2761        renamed.or_else(|| cx.tcx.hir_opt_name(item.hir_id()))
2762    }
2763
2764    let def_id = item.owner_id.to_def_id();
2765    cx.with_param_env(def_id, |cx| {
2766        // These kinds of item either don't need a `name` or accept a `None` one so we handle them
2767        // before.
2768        match item.kind {
2769            ItemKind::Impl(ref impl_) => return clean_impl(impl_, item.owner_id.def_id, cx),
2770            ItemKind::Use(path, kind) => {
2771                return clean_use_statement(
2772                    item,
2773                    get_name(cx, item, renamed),
2774                    path,
2775                    kind,
2776                    cx,
2777                    &mut FxHashSet::default(),
2778                );
2779            }
2780            _ => {}
2781        }
2782
2783        let mut name = get_name(cx, item, renamed).unwrap();
2784
2785        let kind = match item.kind {
2786            ItemKind::Static(mutability, _, ty, body_id) => StaticItem(Static {
2787                type_: Box::new(clean_ty(ty, cx)),
2788                mutability,
2789                expr: Some(body_id),
2790            }),
2791            ItemKind::Const(_, generics, ty, body_id) => ConstantItem(Box::new(Constant {
2792                generics: clean_generics(generics, cx),
2793                type_: clean_ty(ty, cx),
2794                kind: ConstantKind::Local { body: body_id, def_id },
2795            })),
2796            ItemKind::TyAlias(_, generics, ty) => {
2797                *cx.current_type_aliases.entry(def_id).or_insert(0) += 1;
2798                let rustdoc_ty = clean_ty(ty, cx);
2799                let type_ =
2800                    clean_middle_ty(ty::Binder::dummy(lower_ty(cx.tcx, ty)), cx, None, None);
2801                let generics = clean_generics(generics, cx);
2802                if let Some(count) = cx.current_type_aliases.get_mut(&def_id) {
2803                    *count -= 1;
2804                    if *count == 0 {
2805                        cx.current_type_aliases.remove(&def_id);
2806                    }
2807                }
2808
2809                let ty = cx.tcx.type_of(def_id).instantiate_identity();
2810
2811                let mut ret = Vec::new();
2812                let inner_type = clean_ty_alias_inner_type(ty, cx, &mut ret);
2813
2814                ret.push(generate_item_with_correct_attrs(
2815                    cx,
2816                    TypeAliasItem(Box::new(TypeAlias {
2817                        generics,
2818                        inner_type,
2819                        type_: rustdoc_ty,
2820                        item_type: Some(type_),
2821                    })),
2822                    item.owner_id.def_id.to_def_id(),
2823                    name,
2824                    import_ids,
2825                    renamed,
2826                ));
2827                return ret;
2828            }
2829            ItemKind::Enum(_, generics, def) => EnumItem(Enum {
2830                variants: def.variants.iter().map(|v| clean_variant(v, cx)).collect(),
2831                generics: clean_generics(generics, cx),
2832            }),
2833            ItemKind::TraitAlias(_, generics, bounds) => TraitAliasItem(TraitAlias {
2834                generics: clean_generics(generics, cx),
2835                bounds: bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
2836            }),
2837            ItemKind::Union(_, generics, variant_data) => UnionItem(Union {
2838                generics: clean_generics(generics, cx),
2839                fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
2840            }),
2841            ItemKind::Struct(_, generics, variant_data) => StructItem(Struct {
2842                ctor_kind: variant_data.ctor_kind(),
2843                generics: clean_generics(generics, cx),
2844                fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
2845            }),
2846            // FIXME: handle attributes and derives that aren't proc macros, and macros with
2847            // multiple kinds
2848            ItemKind::Macro(_, macro_def, MacroKinds::BANG) => MacroItem(Macro {
2849                source: display_macro_source(cx, name, macro_def),
2850                macro_rules: macro_def.macro_rules,
2851            }),
2852            ItemKind::Macro(_, _, MacroKinds::ATTR) => {
2853                clean_proc_macro(item, &mut name, MacroKind::Attr, cx)
2854            }
2855            ItemKind::Macro(_, _, MacroKinds::DERIVE) => {
2856                clean_proc_macro(item, &mut name, MacroKind::Derive, cx)
2857            }
2858            ItemKind::Macro(_, _, _) => todo!("Handle macros with multiple kinds"),
2859            // proc macros can have a name set by attributes
2860            ItemKind::Fn { ref sig, generics, body: body_id, .. } => {
2861                clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
2862            }
2863            ItemKind::Trait(_, _, _, _, generics, bounds, item_ids) => {
2864                let items = item_ids
2865                    .iter()
2866                    .map(|&ti| clean_trait_item(cx.tcx.hir_trait_item(ti), cx))
2867                    .collect();
2868
2869                TraitItem(Box::new(Trait {
2870                    def_id,
2871                    items,
2872                    generics: clean_generics(generics, cx),
2873                    bounds: bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
2874                }))
2875            }
2876            ItemKind::ExternCrate(orig_name, _) => {
2877                return clean_extern_crate(item, name, orig_name, cx);
2878            }
2879            _ => span_bug!(item.span, "not yet converted"),
2880        };
2881
2882        vec![generate_item_with_correct_attrs(
2883            cx,
2884            kind,
2885            item.owner_id.def_id.to_def_id(),
2886            name,
2887            import_ids,
2888            renamed,
2889        )]
2890    })
2891}
2892
2893fn clean_variant<'tcx>(variant: &hir::Variant<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
2894    let kind = VariantItem(clean_variant_data(&variant.data, &variant.disr_expr, cx));
2895    Item::from_def_id_and_parts(variant.def_id.to_def_id(), Some(variant.ident.name), kind, cx)
2896}
2897
2898fn clean_impl<'tcx>(
2899    impl_: &hir::Impl<'tcx>,
2900    def_id: LocalDefId,
2901    cx: &mut DocContext<'tcx>,
2902) -> Vec<Item> {
2903    let tcx = cx.tcx;
2904    let mut ret = Vec::new();
2905    let trait_ = impl_.of_trait.map(|t| clean_trait_ref(&t.trait_ref, cx));
2906    let items = impl_
2907        .items
2908        .iter()
2909        .map(|&ii| clean_impl_item(tcx.hir_impl_item(ii), cx))
2910        .collect::<Vec<_>>();
2911
2912    // If this impl block is an implementation of the Deref trait, then we
2913    // need to try inlining the target's inherent impl blocks as well.
2914    if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
2915        build_deref_target_impls(cx, &items, &mut ret);
2916    }
2917
2918    let for_ = clean_ty(impl_.self_ty, cx);
2919    let type_alias =
2920        for_.def_id(&cx.cache).and_then(|alias_def_id: DefId| match tcx.def_kind(alias_def_id) {
2921            DefKind::TyAlias => Some(clean_middle_ty(
2922                ty::Binder::dummy(tcx.type_of(def_id).instantiate_identity()),
2923                cx,
2924                Some(def_id.to_def_id()),
2925                None,
2926            )),
2927            _ => None,
2928        });
2929    let mut make_item = |trait_: Option<Path>, for_: Type, items: Vec<Item>| {
2930        let kind = ImplItem(Box::new(Impl {
2931            safety: match impl_.of_trait {
2932                Some(of_trait) => of_trait.safety,
2933                None => hir::Safety::Safe,
2934            },
2935            generics: clean_generics(impl_.generics, cx),
2936            trait_,
2937            for_,
2938            items,
2939            polarity: tcx.impl_polarity(def_id),
2940            kind: if utils::has_doc_flag(tcx, def_id.to_def_id(), sym::fake_variadic) {
2941                ImplKind::FakeVariadic
2942            } else {
2943                ImplKind::Normal
2944            },
2945        }));
2946        Item::from_def_id_and_parts(def_id.to_def_id(), None, kind, cx)
2947    };
2948    if let Some(type_alias) = type_alias {
2949        ret.push(make_item(trait_.clone(), type_alias, items.clone()));
2950    }
2951    ret.push(make_item(trait_, for_, items));
2952    ret
2953}
2954
2955fn clean_extern_crate<'tcx>(
2956    krate: &hir::Item<'tcx>,
2957    name: Symbol,
2958    orig_name: Option<Symbol>,
2959    cx: &mut DocContext<'tcx>,
2960) -> Vec<Item> {
2961    // this is the ID of the `extern crate` statement
2962    let cnum = cx.tcx.extern_mod_stmt_cnum(krate.owner_id.def_id).unwrap_or(LOCAL_CRATE);
2963    // this is the ID of the crate itself
2964    let crate_def_id = cnum.as_def_id();
2965    let attrs = cx.tcx.hir_attrs(krate.hir_id());
2966    let ty_vis = cx.tcx.visibility(krate.owner_id);
2967    let please_inline = ty_vis.is_public()
2968        && attrs.iter().any(|a| {
2969            a.has_name(sym::doc)
2970                && match a.meta_item_list() {
2971                    Some(l) => ast::attr::list_contains_name(&l, sym::inline),
2972                    None => false,
2973                }
2974        })
2975        && !cx.is_json_output();
2976
2977    let krate_owner_def_id = krate.owner_id.def_id;
2978
2979    if please_inline
2980        && let Some(items) = inline::try_inline(
2981            cx,
2982            Res::Def(DefKind::Mod, crate_def_id),
2983            name,
2984            Some((attrs, Some(krate_owner_def_id))),
2985            &mut Default::default(),
2986        )
2987    {
2988        return items;
2989    }
2990
2991    vec![Item::from_def_id_and_parts(
2992        krate_owner_def_id.to_def_id(),
2993        Some(name),
2994        ExternCrateItem { src: orig_name },
2995        cx,
2996    )]
2997}
2998
2999fn clean_use_statement<'tcx>(
3000    import: &hir::Item<'tcx>,
3001    name: Option<Symbol>,
3002    path: &hir::UsePath<'tcx>,
3003    kind: hir::UseKind,
3004    cx: &mut DocContext<'tcx>,
3005    inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
3006) -> Vec<Item> {
3007    let mut items = Vec::new();
3008    let hir::UsePath { segments, ref res, span } = *path;
3009    for res in res.present_items() {
3010        let path = hir::Path { segments, res, span };
3011        items.append(&mut clean_use_statement_inner(import, name, &path, kind, cx, inlined_names));
3012    }
3013    items
3014}
3015
3016fn clean_use_statement_inner<'tcx>(
3017    import: &hir::Item<'tcx>,
3018    name: Option<Symbol>,
3019    path: &hir::Path<'tcx>,
3020    kind: hir::UseKind,
3021    cx: &mut DocContext<'tcx>,
3022    inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
3023) -> Vec<Item> {
3024    if should_ignore_res(path.res) {
3025        return Vec::new();
3026    }
3027    // We need this comparison because some imports (for std types for example)
3028    // are "inserted" as well but directly by the compiler and they should not be
3029    // taken into account.
3030    if import.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
3031        return Vec::new();
3032    }
3033
3034    let visibility = cx.tcx.visibility(import.owner_id);
3035    let attrs = cx.tcx.hir_attrs(import.hir_id());
3036    let inline_attr = hir_attr_lists(attrs, sym::doc).get_word_attr(sym::inline);
3037    let pub_underscore = visibility.is_public() && name == Some(kw::Underscore);
3038    let current_mod = cx.tcx.parent_module_from_def_id(import.owner_id.def_id);
3039    let import_def_id = import.owner_id.def_id;
3040
3041    // The parent of the module in which this import resides. This
3042    // is the same as `current_mod` if that's already the top
3043    // level module.
3044    let parent_mod = cx.tcx.parent_module_from_def_id(current_mod.to_local_def_id());
3045
3046    // This checks if the import can be seen from a higher level module.
3047    // In other words, it checks if the visibility is the equivalent of
3048    // `pub(super)` or higher. If the current module is the top level
3049    // module, there isn't really a parent module, which makes the results
3050    // meaningless. In this case, we make sure the answer is `false`.
3051    let is_visible_from_parent_mod =
3052        visibility.is_accessible_from(parent_mod, cx.tcx) && !current_mod.is_top_level_module();
3053
3054    if pub_underscore && let Some(ref inline) = inline_attr {
3055        struct_span_code_err!(
3056            cx.tcx.dcx(),
3057            inline.span(),
3058            E0780,
3059            "anonymous imports cannot be inlined"
3060        )
3061        .with_span_label(import.span, "anonymous import")
3062        .emit();
3063    }
3064
3065    // We consider inlining the documentation of `pub use` statements, but we
3066    // forcefully don't inline if this is not public or if the
3067    // #[doc(no_inline)] attribute is present.
3068    // Don't inline doc(hidden) imports so they can be stripped at a later stage.
3069    let mut denied = cx.is_json_output()
3070        || !(visibility.is_public()
3071            || (cx.render_options.document_private && is_visible_from_parent_mod))
3072        || pub_underscore
3073        || attrs.iter().any(|a| {
3074            a.has_name(sym::doc)
3075                && match a.meta_item_list() {
3076                    Some(l) => {
3077                        ast::attr::list_contains_name(&l, sym::no_inline)
3078                            || ast::attr::list_contains_name(&l, sym::hidden)
3079                    }
3080                    None => false,
3081                }
3082        });
3083
3084    // Also check whether imports were asked to be inlined, in case we're trying to re-export a
3085    // crate in Rust 2018+
3086    let path = clean_path(path, cx);
3087    let inner = if kind == hir::UseKind::Glob {
3088        if !denied {
3089            let mut visited = DefIdSet::default();
3090            if let Some(items) = inline::try_inline_glob(
3091                cx,
3092                path.res,
3093                current_mod,
3094                &mut visited,
3095                inlined_names,
3096                import,
3097            ) {
3098                return items;
3099            }
3100        }
3101        Import::new_glob(resolve_use_source(cx, path), true)
3102    } else {
3103        let name = name.unwrap();
3104        if inline_attr.is_none()
3105            && let Res::Def(DefKind::Mod, did) = path.res
3106            && !did.is_local()
3107            && did.is_crate_root()
3108        {
3109            // if we're `pub use`ing an extern crate root, don't inline it unless we
3110            // were specifically asked for it
3111            denied = true;
3112        }
3113        if !denied
3114            && let Some(mut items) = inline::try_inline(
3115                cx,
3116                path.res,
3117                name,
3118                Some((attrs, Some(import_def_id))),
3119                &mut Default::default(),
3120            )
3121        {
3122            items.push(Item::from_def_id_and_parts(
3123                import_def_id.to_def_id(),
3124                None,
3125                ImportItem(Import::new_simple(name, resolve_use_source(cx, path), false)),
3126                cx,
3127            ));
3128            return items;
3129        }
3130        Import::new_simple(name, resolve_use_source(cx, path), true)
3131    };
3132
3133    vec![Item::from_def_id_and_parts(import_def_id.to_def_id(), None, ImportItem(inner), cx)]
3134}
3135
3136fn clean_maybe_renamed_foreign_item<'tcx>(
3137    cx: &mut DocContext<'tcx>,
3138    item: &hir::ForeignItem<'tcx>,
3139    renamed: Option<Symbol>,
3140    import_id: Option<LocalDefId>,
3141) -> Item {
3142    let def_id = item.owner_id.to_def_id();
3143    cx.with_param_env(def_id, |cx| {
3144        let kind = match item.kind {
3145            hir::ForeignItemKind::Fn(sig, idents, generics) => ForeignFunctionItem(
3146                clean_function(cx, &sig, generics, ParamsSrc::Idents(idents)),
3147                sig.header.safety(),
3148            ),
3149            hir::ForeignItemKind::Static(ty, mutability, safety) => ForeignStaticItem(
3150                Static { type_: Box::new(clean_ty(ty, cx)), mutability, expr: None },
3151                safety,
3152            ),
3153            hir::ForeignItemKind::Type => ForeignTypeItem,
3154        };
3155
3156        generate_item_with_correct_attrs(
3157            cx,
3158            kind,
3159            item.owner_id.def_id.to_def_id(),
3160            item.ident.name,
3161            import_id.as_slice(),
3162            renamed,
3163        )
3164    })
3165}
3166
3167fn clean_assoc_item_constraint<'tcx>(
3168    constraint: &hir::AssocItemConstraint<'tcx>,
3169    cx: &mut DocContext<'tcx>,
3170) -> AssocItemConstraint {
3171    AssocItemConstraint {
3172        assoc: PathSegment {
3173            name: constraint.ident.name,
3174            args: clean_generic_args(constraint.gen_args, cx),
3175        },
3176        kind: match constraint.kind {
3177            hir::AssocItemConstraintKind::Equality { ref term } => {
3178                AssocItemConstraintKind::Equality { term: clean_hir_term(term, cx) }
3179            }
3180            hir::AssocItemConstraintKind::Bound { bounds } => AssocItemConstraintKind::Bound {
3181                bounds: bounds.iter().filter_map(|b| clean_generic_bound(b, cx)).collect(),
3182            },
3183        },
3184    }
3185}
3186
3187fn clean_bound_vars<'tcx>(
3188    bound_vars: &ty::List<ty::BoundVariableKind>,
3189    cx: &mut DocContext<'tcx>,
3190) -> Vec<GenericParamDef> {
3191    bound_vars
3192        .into_iter()
3193        .filter_map(|var| match var {
3194            ty::BoundVariableKind::Region(ty::BoundRegionKind::Named(def_id)) => {
3195                let name = cx.tcx.item_name(def_id);
3196                if name != kw::UnderscoreLifetime {
3197                    Some(GenericParamDef::lifetime(def_id, name))
3198                } else {
3199                    None
3200                }
3201            }
3202            ty::BoundVariableKind::Ty(ty::BoundTyKind::Param(def_id)) => {
3203                let name = cx.tcx.item_name(def_id);
3204                Some(GenericParamDef {
3205                    name,
3206                    def_id,
3207                    kind: GenericParamDefKind::Type {
3208                        bounds: ThinVec::new(),
3209                        default: None,
3210                        synthetic: false,
3211                    },
3212                })
3213            }
3214            // FIXME(non_lifetime_binders): Support higher-ranked const parameters.
3215            ty::BoundVariableKind::Const => None,
3216            _ => None,
3217        })
3218        .collect()
3219}