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 = match impl_.impl_kind {
1260                    hir::ImplItemImplKind::Inherent { .. } => hir::Defaultness::Final,
1261                    hir::ImplItemImplKind::Trait { defaultness, .. } => defaultness,
1262                };
1263                MethodItem(m, Some(defaultness))
1264            }
1265            hir::ImplItemKind::Type(hir_ty) => {
1266                let type_ = clean_ty(hir_ty, cx);
1267                let generics = clean_generics(impl_.generics, cx);
1268                let item_type =
1269                    clean_middle_ty(ty::Binder::dummy(lower_ty(cx.tcx, hir_ty)), cx, None, None);
1270                AssocTypeItem(
1271                    Box::new(TypeAlias {
1272                        type_,
1273                        generics,
1274                        inner_type: None,
1275                        item_type: Some(item_type),
1276                    }),
1277                    Vec::new(),
1278                )
1279            }
1280        };
1281
1282        Item::from_def_id_and_parts(local_did, Some(impl_.ident.name), inner, cx)
1283    })
1284}
1285
1286pub(crate) fn clean_middle_assoc_item(assoc_item: &ty::AssocItem, cx: &mut DocContext<'_>) -> Item {
1287    let tcx = cx.tcx;
1288    let kind = match assoc_item.kind {
1289        ty::AssocKind::Const { .. } => {
1290            let ty = clean_middle_ty(
1291                ty::Binder::dummy(tcx.type_of(assoc_item.def_id).instantiate_identity()),
1292                cx,
1293                Some(assoc_item.def_id),
1294                None,
1295            );
1296
1297            let mut generics = clean_ty_generics(cx, assoc_item.def_id);
1298            simplify::move_bounds_to_generic_parameters(&mut generics);
1299
1300            match assoc_item.container {
1301                ty::AssocContainer::InherentImpl | ty::AssocContainer::TraitImpl(_) => {
1302                    ImplAssocConstItem(Box::new(Constant {
1303                        generics,
1304                        kind: ConstantKind::Extern { def_id: assoc_item.def_id },
1305                        type_: ty,
1306                    }))
1307                }
1308                ty::AssocContainer::Trait => {
1309                    if tcx.defaultness(assoc_item.def_id).has_value() {
1310                        ProvidedAssocConstItem(Box::new(Constant {
1311                            generics,
1312                            kind: ConstantKind::Extern { def_id: assoc_item.def_id },
1313                            type_: ty,
1314                        }))
1315                    } else {
1316                        RequiredAssocConstItem(generics, Box::new(ty))
1317                    }
1318                }
1319            }
1320        }
1321        ty::AssocKind::Fn { has_self, .. } => {
1322            let mut item = inline::build_function(cx, assoc_item.def_id);
1323
1324            if has_self {
1325                let self_ty = match assoc_item.container {
1326                    ty::AssocContainer::InherentImpl | ty::AssocContainer::TraitImpl(_) => {
1327                        tcx.type_of(assoc_item.container_id(tcx)).instantiate_identity()
1328                    }
1329                    ty::AssocContainer::Trait => tcx.types.self_param,
1330                };
1331                let self_param_ty =
1332                    tcx.fn_sig(assoc_item.def_id).instantiate_identity().input(0).skip_binder();
1333                if self_param_ty == self_ty {
1334                    item.decl.inputs[0].type_ = SelfTy;
1335                } else if let ty::Ref(_, ty, _) = *self_param_ty.kind()
1336                    && ty == self_ty
1337                {
1338                    match item.decl.inputs[0].type_ {
1339                        BorrowedRef { ref mut type_, .. } => **type_ = SelfTy,
1340                        _ => unreachable!(),
1341                    }
1342                }
1343            }
1344
1345            let provided = match assoc_item.container {
1346                ty::AssocContainer::InherentImpl | ty::AssocContainer::TraitImpl(_) => true,
1347                ty::AssocContainer::Trait => assoc_item.defaultness(tcx).has_value(),
1348            };
1349            if provided {
1350                let defaultness = match assoc_item.container {
1351                    ty::AssocContainer::TraitImpl(_) => Some(assoc_item.defaultness(tcx)),
1352                    ty::AssocContainer::InherentImpl | ty::AssocContainer::Trait => None,
1353                };
1354                MethodItem(item, defaultness)
1355            } else {
1356                RequiredMethodItem(item)
1357            }
1358        }
1359        ty::AssocKind::Type { .. } => {
1360            let my_name = assoc_item.name();
1361
1362            fn param_eq_arg(param: &GenericParamDef, arg: &GenericArg) -> bool {
1363                match (&param.kind, arg) {
1364                    (GenericParamDefKind::Type { .. }, GenericArg::Type(Type::Generic(ty)))
1365                        if *ty == param.name =>
1366                    {
1367                        true
1368                    }
1369                    (GenericParamDefKind::Lifetime { .. }, GenericArg::Lifetime(Lifetime(lt)))
1370                        if *lt == param.name =>
1371                    {
1372                        true
1373                    }
1374                    (GenericParamDefKind::Const { .. }, GenericArg::Const(c)) => match &**c {
1375                        ConstantKind::TyConst { expr } => **expr == *param.name.as_str(),
1376                        _ => false,
1377                    },
1378                    _ => false,
1379                }
1380            }
1381
1382            let mut predicates = tcx.explicit_predicates_of(assoc_item.def_id).predicates;
1383            if let ty::AssocContainer::Trait = assoc_item.container {
1384                let bounds = tcx.explicit_item_bounds(assoc_item.def_id).iter_identity_copied();
1385                predicates = tcx.arena.alloc_from_iter(bounds.chain(predicates.iter().copied()));
1386            }
1387            let mut generics = clean_ty_generics_inner(
1388                cx,
1389                tcx.generics_of(assoc_item.def_id),
1390                ty::GenericPredicates { parent: None, predicates },
1391            );
1392            simplify::move_bounds_to_generic_parameters(&mut generics);
1393
1394            if let ty::AssocContainer::Trait = assoc_item.container {
1395                // Move bounds that are (likely) directly attached to the associated type
1396                // from the where-clause to the associated type.
1397                // There is no guarantee that this is what the user actually wrote but we have
1398                // no way of knowing.
1399                let mut bounds: Vec<GenericBound> = Vec::new();
1400                generics.where_predicates.retain_mut(|pred| match *pred {
1401                    WherePredicate::BoundPredicate {
1402                        ty:
1403                            QPath(box QPathData {
1404                                ref assoc,
1405                                ref self_type,
1406                                trait_: Some(ref trait_),
1407                                ..
1408                            }),
1409                        bounds: ref mut pred_bounds,
1410                        ..
1411                    } => {
1412                        if assoc.name != my_name {
1413                            return true;
1414                        }
1415                        if trait_.def_id() != assoc_item.container_id(tcx) {
1416                            return true;
1417                        }
1418                        if *self_type != SelfTy {
1419                            return true;
1420                        }
1421                        match &assoc.args {
1422                            GenericArgs::AngleBracketed { args, constraints } => {
1423                                if !constraints.is_empty()
1424                                    || generics
1425                                        .params
1426                                        .iter()
1427                                        .zip(args.iter())
1428                                        .any(|(param, arg)| !param_eq_arg(param, arg))
1429                                {
1430                                    return true;
1431                                }
1432                            }
1433                            GenericArgs::Parenthesized { .. } => {
1434                                // The only time this happens is if we're inside the rustdoc for Fn(),
1435                                // which only has one associated type, which is not a GAT, so whatever.
1436                            }
1437                            GenericArgs::ReturnTypeNotation => {
1438                                // Never move these.
1439                            }
1440                        }
1441                        bounds.extend(mem::take(pred_bounds));
1442                        false
1443                    }
1444                    _ => true,
1445                });
1446
1447                bounds.retain(|b| {
1448                    // FIXME(sized-hierarchy): Always skip `MetaSized` bounds so that only `?Sized`
1449                    // is shown and none of the new sizedness traits leak into documentation.
1450                    !b.is_meta_sized_bound(cx)
1451                });
1452
1453                // Our Sized/?Sized bound didn't get handled when creating the generics
1454                // because we didn't actually get our whole set of bounds until just now
1455                // (some of them may have come from the trait). If we do have a sized
1456                // bound, we remove it, and if we don't then we add the `?Sized` bound
1457                // at the end.
1458                match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1459                    Some(i) => {
1460                        bounds.remove(i);
1461                    }
1462                    None => bounds.push(GenericBound::maybe_sized(cx)),
1463                }
1464
1465                if tcx.defaultness(assoc_item.def_id).has_value() {
1466                    AssocTypeItem(
1467                        Box::new(TypeAlias {
1468                            type_: clean_middle_ty(
1469                                ty::Binder::dummy(
1470                                    tcx.type_of(assoc_item.def_id).instantiate_identity(),
1471                                ),
1472                                cx,
1473                                Some(assoc_item.def_id),
1474                                None,
1475                            ),
1476                            generics,
1477                            inner_type: None,
1478                            item_type: None,
1479                        }),
1480                        bounds,
1481                    )
1482                } else {
1483                    RequiredAssocTypeItem(generics, bounds)
1484                }
1485            } else {
1486                AssocTypeItem(
1487                    Box::new(TypeAlias {
1488                        type_: clean_middle_ty(
1489                            ty::Binder::dummy(
1490                                tcx.type_of(assoc_item.def_id).instantiate_identity(),
1491                            ),
1492                            cx,
1493                            Some(assoc_item.def_id),
1494                            None,
1495                        ),
1496                        generics,
1497                        inner_type: None,
1498                        item_type: None,
1499                    }),
1500                    // Associated types inside trait or inherent impls are not allowed to have
1501                    // item bounds. Thus we don't attempt to move any bounds there.
1502                    Vec::new(),
1503                )
1504            }
1505        }
1506    };
1507
1508    Item::from_def_id_and_parts(assoc_item.def_id, Some(assoc_item.name()), kind, cx)
1509}
1510
1511fn first_non_private_clean_path<'tcx>(
1512    cx: &mut DocContext<'tcx>,
1513    path: &hir::Path<'tcx>,
1514    new_path_segments: &'tcx [hir::PathSegment<'tcx>],
1515    new_path_span: rustc_span::Span,
1516) -> Path {
1517    let new_hir_path =
1518        hir::Path { segments: new_path_segments, res: path.res, span: new_path_span };
1519    let mut new_clean_path = clean_path(&new_hir_path, cx);
1520    // In here we need to play with the path data one last time to provide it the
1521    // missing `args` and `res` of the final `Path` we get, which, since it comes
1522    // from a re-export, doesn't have the generics that were originally there, so
1523    // we add them by hand.
1524    if let Some(path_last) = path.segments.last().as_ref()
1525        && let Some(new_path_last) = new_clean_path.segments[..].last_mut()
1526        && let Some(path_last_args) = path_last.args.as_ref()
1527        && path_last.args.is_some()
1528    {
1529        assert!(new_path_last.args.is_empty());
1530        new_path_last.args = clean_generic_args(path_last_args, cx);
1531    }
1532    new_clean_path
1533}
1534
1535/// The goal of this function is to return the first `Path` which is not private (ie not private
1536/// or `doc(hidden)`). If it's not possible, it'll return the "end type".
1537///
1538/// If the path is not a re-export or is public, it'll return `None`.
1539fn first_non_private<'tcx>(
1540    cx: &mut DocContext<'tcx>,
1541    hir_id: hir::HirId,
1542    path: &hir::Path<'tcx>,
1543) -> Option<Path> {
1544    let target_def_id = path.res.opt_def_id()?;
1545    let (parent_def_id, ident) = match &path.segments {
1546        [] => return None,
1547        // Relative paths are available in the same scope as the owner.
1548        [leaf] => (cx.tcx.local_parent(hir_id.owner.def_id), leaf.ident),
1549        // So are self paths.
1550        [parent, leaf] if parent.ident.name == kw::SelfLower => {
1551            (cx.tcx.local_parent(hir_id.owner.def_id), leaf.ident)
1552        }
1553        // Crate paths are not. We start from the crate root.
1554        [parent, leaf] if matches!(parent.ident.name, kw::Crate | kw::PathRoot) => {
1555            (LOCAL_CRATE.as_def_id().as_local()?, leaf.ident)
1556        }
1557        [parent, leaf] if parent.ident.name == kw::Super => {
1558            let parent_mod = cx.tcx.parent_module(hir_id);
1559            if let Some(super_parent) = cx.tcx.opt_local_parent(parent_mod.to_local_def_id()) {
1560                (super_parent, leaf.ident)
1561            } else {
1562                // If we can't find the parent of the parent, then the parent is already the crate.
1563                (LOCAL_CRATE.as_def_id().as_local()?, leaf.ident)
1564            }
1565        }
1566        // Absolute paths are not. We start from the parent of the item.
1567        [.., parent, leaf] => (parent.res.opt_def_id()?.as_local()?, leaf.ident),
1568    };
1569    // First we try to get the `DefId` of the item.
1570    for child in
1571        cx.tcx.module_children_local(parent_def_id).iter().filter(move |c| c.ident == ident)
1572    {
1573        if let Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) = child.res {
1574            continue;
1575        }
1576
1577        if let Some(def_id) = child.res.opt_def_id()
1578            && target_def_id == def_id
1579        {
1580            let mut last_path_res = None;
1581            'reexps: for reexp in child.reexport_chain.iter() {
1582                if let Some(use_def_id) = reexp.id()
1583                    && let Some(local_use_def_id) = use_def_id.as_local()
1584                    && let hir::Node::Item(item) = cx.tcx.hir_node_by_def_id(local_use_def_id)
1585                    && let hir::ItemKind::Use(path, hir::UseKind::Single(_)) = item.kind
1586                {
1587                    for res in path.res.present_items() {
1588                        if let Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) = res {
1589                            continue;
1590                        }
1591                        if (cx.render_options.document_hidden ||
1592                            !cx.tcx.is_doc_hidden(use_def_id)) &&
1593                            // We never check for "cx.render_options.document_private"
1594                            // because if a re-export is not fully public, it's never
1595                            // documented.
1596                            cx.tcx.local_visibility(local_use_def_id).is_public()
1597                        {
1598                            break 'reexps;
1599                        }
1600                        last_path_res = Some((path, res));
1601                        continue 'reexps;
1602                    }
1603                }
1604            }
1605            if !child.reexport_chain.is_empty() {
1606                // So in here, we use the data we gathered from iterating the reexports. If
1607                // `last_path_res` is set, it can mean two things:
1608                //
1609                // 1. We found a public reexport.
1610                // 2. We didn't find a public reexport so it's the "end type" path.
1611                if let Some((new_path, _)) = last_path_res {
1612                    return Some(first_non_private_clean_path(
1613                        cx,
1614                        path,
1615                        new_path.segments,
1616                        new_path.span,
1617                    ));
1618                }
1619                // If `last_path_res` is `None`, it can mean two things:
1620                //
1621                // 1. The re-export is public, no need to change anything, just use the path as is.
1622                // 2. Nothing was found, so let's just return the original path.
1623                return None;
1624            }
1625        }
1626    }
1627    None
1628}
1629
1630fn clean_qpath<'tcx>(hir_ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1631    let hir::Ty { hir_id, span, ref kind } = *hir_ty;
1632    let hir::TyKind::Path(qpath) = kind else { unreachable!() };
1633
1634    match qpath {
1635        hir::QPath::Resolved(None, path) => {
1636            if let Res::Def(DefKind::TyParam, did) = path.res {
1637                if let Some(new_ty) = cx.args.get(&did).and_then(|p| p.as_ty()).cloned() {
1638                    return new_ty;
1639                }
1640                if let Some(bounds) = cx.impl_trait_bounds.remove(&did.into()) {
1641                    return ImplTrait(bounds);
1642                }
1643            }
1644
1645            if let Some(expanded) = maybe_expand_private_type_alias(cx, path) {
1646                expanded
1647            } else {
1648                // First we check if it's a private re-export.
1649                let path = if let Some(path) = first_non_private(cx, hir_id, path) {
1650                    path
1651                } else {
1652                    clean_path(path, cx)
1653                };
1654                resolve_type(cx, path)
1655            }
1656        }
1657        hir::QPath::Resolved(Some(qself), p) => {
1658            // Try to normalize `<X as Y>::T` to a type
1659            let ty = lower_ty(cx.tcx, hir_ty);
1660            // `hir_to_ty` can return projection types with escaping vars for GATs, e.g. `<() as Trait>::Gat<'_>`
1661            if !ty.has_escaping_bound_vars()
1662                && let Some(normalized_value) = normalize(cx, ty::Binder::dummy(ty))
1663            {
1664                return clean_middle_ty(normalized_value, cx, None, None);
1665            }
1666
1667            let trait_segments = &p.segments[..p.segments.len() - 1];
1668            let trait_def = cx.tcx.parent(p.res.def_id());
1669            let trait_ = self::Path {
1670                res: Res::Def(DefKind::Trait, trait_def),
1671                segments: trait_segments.iter().map(|x| clean_path_segment(x, cx)).collect(),
1672            };
1673            register_res(cx, trait_.res);
1674            let self_def_id = DefId::local(qself.hir_id.owner.def_id.local_def_index);
1675            let self_type = clean_ty(qself, cx);
1676            let should_fully_qualify =
1677                should_fully_qualify_path(Some(self_def_id), &trait_, &self_type);
1678            Type::QPath(Box::new(QPathData {
1679                assoc: clean_path_segment(p.segments.last().expect("segments were empty"), cx),
1680                should_fully_qualify,
1681                self_type,
1682                trait_: Some(trait_),
1683            }))
1684        }
1685        hir::QPath::TypeRelative(qself, segment) => {
1686            let ty = lower_ty(cx.tcx, hir_ty);
1687            let self_type = clean_ty(qself, cx);
1688
1689            let (trait_, should_fully_qualify) = match ty.kind() {
1690                ty::Alias(ty::Projection, proj) => {
1691                    let res = Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id);
1692                    let trait_ = clean_path(&hir::Path { span, res, segments: &[] }, cx);
1693                    register_res(cx, trait_.res);
1694                    let self_def_id = res.opt_def_id();
1695                    let should_fully_qualify =
1696                        should_fully_qualify_path(self_def_id, &trait_, &self_type);
1697
1698                    (Some(trait_), should_fully_qualify)
1699                }
1700                ty::Alias(ty::Inherent, _) => (None, false),
1701                // Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
1702                ty::Error(_) => return Type::Infer,
1703                _ => bug!("clean: expected associated type, found `{ty:?}`"),
1704            };
1705
1706            Type::QPath(Box::new(QPathData {
1707                assoc: clean_path_segment(segment, cx),
1708                should_fully_qualify,
1709                self_type,
1710                trait_,
1711            }))
1712        }
1713        hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1714    }
1715}
1716
1717fn maybe_expand_private_type_alias<'tcx>(
1718    cx: &mut DocContext<'tcx>,
1719    path: &hir::Path<'tcx>,
1720) -> Option<Type> {
1721    let Res::Def(DefKind::TyAlias, def_id) = path.res else { return None };
1722    // Substitute private type aliases
1723    let def_id = def_id.as_local()?;
1724    let alias = if !cx.cache.effective_visibilities.is_exported(cx.tcx, def_id.to_def_id())
1725        && !cx.current_type_aliases.contains_key(&def_id.to_def_id())
1726    {
1727        &cx.tcx.hir_expect_item(def_id).kind
1728    } else {
1729        return None;
1730    };
1731    let hir::ItemKind::TyAlias(_, generics, ty) = alias else { return None };
1732
1733    let final_seg = &path.segments.last().expect("segments were empty");
1734    let mut args = DefIdMap::default();
1735    let generic_args = final_seg.args();
1736
1737    let mut indices: hir::GenericParamCount = Default::default();
1738    for param in generics.params.iter() {
1739        match param.kind {
1740            hir::GenericParamKind::Lifetime { .. } => {
1741                let mut j = 0;
1742                let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1743                    hir::GenericArg::Lifetime(lt) => {
1744                        if indices.lifetimes == j {
1745                            return Some(lt);
1746                        }
1747                        j += 1;
1748                        None
1749                    }
1750                    _ => None,
1751                });
1752                if let Some(lt) = lifetime {
1753                    let lt = if !lt.is_anonymous() {
1754                        clean_lifetime(lt, cx)
1755                    } else {
1756                        Lifetime::elided()
1757                    };
1758                    args.insert(param.def_id.to_def_id(), GenericArg::Lifetime(lt));
1759                }
1760                indices.lifetimes += 1;
1761            }
1762            hir::GenericParamKind::Type { ref default, .. } => {
1763                let mut j = 0;
1764                let type_ = generic_args.args.iter().find_map(|arg| match arg {
1765                    hir::GenericArg::Type(ty) => {
1766                        if indices.types == j {
1767                            return Some(ty.as_unambig_ty());
1768                        }
1769                        j += 1;
1770                        None
1771                    }
1772                    _ => None,
1773                });
1774                if let Some(ty) = type_.or(*default) {
1775                    args.insert(param.def_id.to_def_id(), GenericArg::Type(clean_ty(ty, cx)));
1776                }
1777                indices.types += 1;
1778            }
1779            // FIXME(#82852): Instantiate const parameters.
1780            hir::GenericParamKind::Const { .. } => {}
1781        }
1782    }
1783
1784    Some(cx.enter_alias(args, def_id.to_def_id(), |cx| {
1785        cx.with_param_env(def_id.to_def_id(), |cx| clean_ty(ty, cx))
1786    }))
1787}
1788
1789pub(crate) fn clean_ty<'tcx>(ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1790    use rustc_hir::*;
1791
1792    match ty.kind {
1793        TyKind::Never => Primitive(PrimitiveType::Never),
1794        TyKind::Ptr(ref m) => RawPointer(m.mutbl, Box::new(clean_ty(m.ty, cx))),
1795        TyKind::Ref(l, ref m) => {
1796            let lifetime = if l.is_anonymous() { None } else { Some(clean_lifetime(l, cx)) };
1797            BorrowedRef { lifetime, mutability: m.mutbl, type_: Box::new(clean_ty(m.ty, cx)) }
1798        }
1799        TyKind::Slice(ty) => Slice(Box::new(clean_ty(ty, cx))),
1800        TyKind::Pat(ty, pat) => Type::Pat(Box::new(clean_ty(ty, cx)), format!("{pat:?}").into()),
1801        TyKind::Array(ty, const_arg) => {
1802            // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1803            // as we currently do not supply the parent generics to anonymous constants
1804            // but do allow `ConstKind::Param`.
1805            //
1806            // `const_eval_poly` tries to first substitute generic parameters which
1807            // results in an ICE while manually constructing the constant and using `eval`
1808            // does nothing for `ConstKind::Param`.
1809            let length = match const_arg.kind {
1810                hir::ConstArgKind::Infer(..) => "_".to_string(),
1811                hir::ConstArgKind::Anon(hir::AnonConst { def_id, .. }) => {
1812                    let ct = lower_const_arg_for_rustdoc(cx.tcx, const_arg, FeedConstTy::No);
1813                    let typing_env = ty::TypingEnv::post_analysis(cx.tcx, *def_id);
1814                    let ct = cx.tcx.normalize_erasing_regions(typing_env, ct);
1815                    print_const(cx, ct)
1816                }
1817                hir::ConstArgKind::Path(..) => {
1818                    let ct = lower_const_arg_for_rustdoc(cx.tcx, const_arg, FeedConstTy::No);
1819                    print_const(cx, ct)
1820                }
1821            };
1822            Array(Box::new(clean_ty(ty, cx)), length.into())
1823        }
1824        TyKind::Tup(tys) => Tuple(tys.iter().map(|ty| clean_ty(ty, cx)).collect()),
1825        TyKind::OpaqueDef(ty) => {
1826            ImplTrait(ty.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect())
1827        }
1828        TyKind::Path(_) => clean_qpath(ty, cx),
1829        TyKind::TraitObject(bounds, lifetime) => {
1830            let bounds = bounds.iter().map(|bound| clean_poly_trait_ref(bound, cx)).collect();
1831            let lifetime = if !lifetime.is_elided() {
1832                Some(clean_lifetime(lifetime.pointer(), cx))
1833            } else {
1834                None
1835            };
1836            DynTrait(bounds, lifetime)
1837        }
1838        TyKind::FnPtr(barefn) => BareFunction(Box::new(clean_bare_fn_ty(barefn, cx))),
1839        TyKind::UnsafeBinder(unsafe_binder_ty) => {
1840            UnsafeBinder(Box::new(clean_unsafe_binder_ty(unsafe_binder_ty, cx)))
1841        }
1842        // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
1843        TyKind::Infer(())
1844        | TyKind::Err(_)
1845        | TyKind::Typeof(..)
1846        | TyKind::InferDelegation(..)
1847        | TyKind::TraitAscription(_) => Infer,
1848    }
1849}
1850
1851/// Returns `None` if the type could not be normalized
1852fn normalize<'tcx>(
1853    cx: &DocContext<'tcx>,
1854    ty: ty::Binder<'tcx, Ty<'tcx>>,
1855) -> Option<ty::Binder<'tcx, Ty<'tcx>>> {
1856    // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1857    if !cx.tcx.sess.opts.unstable_opts.normalize_docs {
1858        return None;
1859    }
1860
1861    use rustc_middle::traits::ObligationCause;
1862    use rustc_trait_selection::infer::TyCtxtInferExt;
1863    use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
1864
1865    // Try to normalize `<X as Y>::T` to a type
1866    let infcx = cx.tcx.infer_ctxt().build(TypingMode::non_body_analysis());
1867    let normalized = infcx
1868        .at(&ObligationCause::dummy(), cx.param_env)
1869        .query_normalize(ty)
1870        .map(|resolved| infcx.resolve_vars_if_possible(resolved.value));
1871    match normalized {
1872        Ok(normalized_value) => {
1873            debug!("normalized {ty:?} to {normalized_value:?}");
1874            Some(normalized_value)
1875        }
1876        Err(err) => {
1877            debug!("failed to normalize {ty:?}: {err:?}");
1878            None
1879        }
1880    }
1881}
1882
1883fn clean_trait_object_lifetime_bound<'tcx>(
1884    region: ty::Region<'tcx>,
1885    container: Option<ContainerTy<'_, 'tcx>>,
1886    preds: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
1887    tcx: TyCtxt<'tcx>,
1888) -> Option<Lifetime> {
1889    if can_elide_trait_object_lifetime_bound(region, container, preds, tcx) {
1890        return None;
1891    }
1892
1893    // Since there is a semantic difference between an implicitly elided (i.e. "defaulted") object
1894    // lifetime and an explicitly elided object lifetime (`'_`), we intentionally don't hide the
1895    // latter contrary to `clean_middle_region`.
1896    match region.kind() {
1897        ty::ReStatic => Some(Lifetime::statik()),
1898        ty::ReEarlyParam(region) => Some(Lifetime(region.name)),
1899        ty::ReBound(_, ty::BoundRegion { kind: ty::BoundRegionKind::Named(def_id), .. }) => {
1900            Some(Lifetime(tcx.item_name(def_id)))
1901        }
1902        ty::ReBound(..)
1903        | ty::ReLateParam(_)
1904        | ty::ReVar(_)
1905        | ty::RePlaceholder(_)
1906        | ty::ReErased
1907        | ty::ReError(_) => None,
1908    }
1909}
1910
1911fn can_elide_trait_object_lifetime_bound<'tcx>(
1912    region: ty::Region<'tcx>,
1913    container: Option<ContainerTy<'_, 'tcx>>,
1914    preds: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
1915    tcx: TyCtxt<'tcx>,
1916) -> bool {
1917    // Below we quote extracts from https://doc.rust-lang.org/stable/reference/lifetime-elision.html#default-trait-object-lifetimes
1918
1919    // > If the trait object is used as a type argument of a generic type then the containing type is
1920    // > first used to try to infer a bound.
1921    let default = container
1922        .map_or(ObjectLifetimeDefault::Empty, |container| container.object_lifetime_default(tcx));
1923
1924    // > If there is a unique bound from the containing type then that is the default
1925    // If there is a default object lifetime and the given region is lexically equal to it, elide it.
1926    match default {
1927        ObjectLifetimeDefault::Static => return region.kind() == ty::ReStatic,
1928        // FIXME(fmease): Don't compare lexically but respect de Bruijn indices etc. to handle shadowing correctly.
1929        ObjectLifetimeDefault::Arg(default) => {
1930            return region.get_name(tcx) == default.get_name(tcx);
1931        }
1932        // > If there is more than one bound from the containing type then an explicit bound must be specified
1933        // Due to ambiguity there is no default trait-object lifetime and thus elision is impossible.
1934        // Don't elide the lifetime.
1935        ObjectLifetimeDefault::Ambiguous => return false,
1936        // There is no meaningful bound. Further processing is needed...
1937        ObjectLifetimeDefault::Empty => {}
1938    }
1939
1940    // > If neither of those rules apply, then the bounds on the trait are used:
1941    match *object_region_bounds(tcx, preds) {
1942        // > If the trait has no lifetime bounds, then the lifetime is inferred in expressions
1943        // > and is 'static outside of expressions.
1944        // FIXME: If we are in an expression context (i.e. fn bodies and const exprs) then the default is
1945        // `'_` and not `'static`. Only if we are in a non-expression one, the default is `'static`.
1946        // Note however that at the time of this writing it should be fine to disregard this subtlety
1947        // as we neither render const exprs faithfully anyway (hiding them in some places or using `_` instead)
1948        // nor show the contents of fn bodies.
1949        [] => region.kind() == ty::ReStatic,
1950        // > If the trait is defined with a single lifetime bound then that bound is used.
1951        // > If 'static is used for any lifetime bound then 'static is used.
1952        // FIXME(fmease): Don't compare lexically but respect de Bruijn indices etc. to handle shadowing correctly.
1953        [object_region] => object_region.get_name(tcx) == region.get_name(tcx),
1954        // There are several distinct trait regions and none are `'static`.
1955        // Due to ambiguity there is no default trait-object lifetime and thus elision is impossible.
1956        // Don't elide the lifetime.
1957        _ => false,
1958    }
1959}
1960
1961#[derive(Debug)]
1962pub(crate) enum ContainerTy<'a, 'tcx> {
1963    Ref(ty::Region<'tcx>),
1964    Regular {
1965        ty: DefId,
1966        /// The arguments *have* to contain an arg for the self type if the corresponding generics
1967        /// contain a self type.
1968        args: ty::Binder<'tcx, &'a [ty::GenericArg<'tcx>]>,
1969        arg: usize,
1970    },
1971}
1972
1973impl<'tcx> ContainerTy<'_, 'tcx> {
1974    fn object_lifetime_default(self, tcx: TyCtxt<'tcx>) -> ObjectLifetimeDefault<'tcx> {
1975        match self {
1976            Self::Ref(region) => ObjectLifetimeDefault::Arg(region),
1977            Self::Regular { ty: container, args, arg: index } => {
1978                let (DefKind::Struct
1979                | DefKind::Union
1980                | DefKind::Enum
1981                | DefKind::TyAlias
1982                | DefKind::Trait) = tcx.def_kind(container)
1983                else {
1984                    return ObjectLifetimeDefault::Empty;
1985                };
1986
1987                let generics = tcx.generics_of(container);
1988                debug_assert_eq!(generics.parent_count, 0);
1989
1990                let param = generics.own_params[index].def_id;
1991                let default = tcx.object_lifetime_default(param);
1992                match default {
1993                    rbv::ObjectLifetimeDefault::Param(lifetime) => {
1994                        // The index is relative to the parent generics but since we don't have any,
1995                        // we don't need to translate it.
1996                        let index = generics.param_def_id_to_index[&lifetime];
1997                        let arg = args.skip_binder()[index as usize].expect_region();
1998                        ObjectLifetimeDefault::Arg(arg)
1999                    }
2000                    rbv::ObjectLifetimeDefault::Empty => ObjectLifetimeDefault::Empty,
2001                    rbv::ObjectLifetimeDefault::Static => ObjectLifetimeDefault::Static,
2002                    rbv::ObjectLifetimeDefault::Ambiguous => ObjectLifetimeDefault::Ambiguous,
2003                }
2004            }
2005        }
2006    }
2007}
2008
2009#[derive(Debug, Clone, Copy)]
2010pub(crate) enum ObjectLifetimeDefault<'tcx> {
2011    Empty,
2012    Static,
2013    Ambiguous,
2014    Arg(ty::Region<'tcx>),
2015}
2016
2017#[instrument(level = "trace", skip(cx), ret)]
2018pub(crate) fn clean_middle_ty<'tcx>(
2019    bound_ty: ty::Binder<'tcx, Ty<'tcx>>,
2020    cx: &mut DocContext<'tcx>,
2021    parent_def_id: Option<DefId>,
2022    container: Option<ContainerTy<'_, 'tcx>>,
2023) -> Type {
2024    let bound_ty = normalize(cx, bound_ty).unwrap_or(bound_ty);
2025    match *bound_ty.skip_binder().kind() {
2026        ty::Never => Primitive(PrimitiveType::Never),
2027        ty::Bool => Primitive(PrimitiveType::Bool),
2028        ty::Char => Primitive(PrimitiveType::Char),
2029        ty::Int(int_ty) => Primitive(int_ty.into()),
2030        ty::Uint(uint_ty) => Primitive(uint_ty.into()),
2031        ty::Float(float_ty) => Primitive(float_ty.into()),
2032        ty::Str => Primitive(PrimitiveType::Str),
2033        ty::Slice(ty) => Slice(Box::new(clean_middle_ty(bound_ty.rebind(ty), cx, None, None))),
2034        ty::Pat(ty, pat) => Type::Pat(
2035            Box::new(clean_middle_ty(bound_ty.rebind(ty), cx, None, None)),
2036            format!("{pat:?}").into_boxed_str(),
2037        ),
2038        ty::Array(ty, n) => {
2039            let n = cx.tcx.normalize_erasing_regions(cx.typing_env(), n);
2040            let n = print_const(cx, n);
2041            Array(Box::new(clean_middle_ty(bound_ty.rebind(ty), cx, None, None)), n.into())
2042        }
2043        ty::RawPtr(ty, mutbl) => {
2044            RawPointer(mutbl, Box::new(clean_middle_ty(bound_ty.rebind(ty), cx, None, None)))
2045        }
2046        ty::Ref(r, ty, mutbl) => BorrowedRef {
2047            lifetime: clean_middle_region(r, cx),
2048            mutability: mutbl,
2049            type_: Box::new(clean_middle_ty(
2050                bound_ty.rebind(ty),
2051                cx,
2052                None,
2053                Some(ContainerTy::Ref(r)),
2054            )),
2055        },
2056        ty::FnDef(..) | ty::FnPtr(..) => {
2057            // FIXME: should we merge the outer and inner binders somehow?
2058            let sig = bound_ty.skip_binder().fn_sig(cx.tcx);
2059            let decl = clean_poly_fn_sig(cx, None, sig);
2060            let generic_params = clean_bound_vars(sig.bound_vars(), cx);
2061
2062            BareFunction(Box::new(BareFunctionDecl {
2063                safety: sig.safety(),
2064                generic_params,
2065                decl,
2066                abi: sig.abi(),
2067            }))
2068        }
2069        ty::UnsafeBinder(inner) => {
2070            let generic_params = clean_bound_vars(inner.bound_vars(), cx);
2071            let ty = clean_middle_ty(inner.into(), cx, None, None);
2072            UnsafeBinder(Box::new(UnsafeBinderTy { generic_params, ty }))
2073        }
2074        ty::Adt(def, args) => {
2075            let did = def.did();
2076            let kind = match def.adt_kind() {
2077                AdtKind::Struct => ItemType::Struct,
2078                AdtKind::Union => ItemType::Union,
2079                AdtKind::Enum => ItemType::Enum,
2080            };
2081            inline::record_extern_fqn(cx, did, kind);
2082            let path = clean_middle_path(cx, did, false, ThinVec::new(), bound_ty.rebind(args));
2083            Type::Path { path }
2084        }
2085        ty::Foreign(did) => {
2086            inline::record_extern_fqn(cx, did, ItemType::ForeignType);
2087            let path = clean_middle_path(
2088                cx,
2089                did,
2090                false,
2091                ThinVec::new(),
2092                ty::Binder::dummy(ty::GenericArgs::empty()),
2093            );
2094            Type::Path { path }
2095        }
2096        ty::Dynamic(obj, reg) => {
2097            // HACK: pick the first `did` as the `did` of the trait object. Someone
2098            // might want to implement "native" support for marker-trait-only
2099            // trait objects.
2100            let mut dids = obj.auto_traits();
2101            let did = obj
2102                .principal_def_id()
2103                .or_else(|| dids.next())
2104                .unwrap_or_else(|| panic!("found trait object `{bound_ty:?}` with no traits?"));
2105            let args = match obj.principal() {
2106                Some(principal) => principal.map_bound(|p| p.args),
2107                // marker traits have no args.
2108                _ => ty::Binder::dummy(ty::GenericArgs::empty()),
2109            };
2110
2111            inline::record_extern_fqn(cx, did, ItemType::Trait);
2112
2113            let lifetime = clean_trait_object_lifetime_bound(reg, container, obj, cx.tcx);
2114
2115            let mut bounds = dids
2116                .map(|did| {
2117                    let empty = ty::Binder::dummy(ty::GenericArgs::empty());
2118                    let path = clean_middle_path(cx, did, false, ThinVec::new(), empty);
2119                    inline::record_extern_fqn(cx, did, ItemType::Trait);
2120                    PolyTrait { trait_: path, generic_params: Vec::new() }
2121                })
2122                .collect::<Vec<_>>();
2123
2124            let constraints = obj
2125                .projection_bounds()
2126                .map(|pb| AssocItemConstraint {
2127                    assoc: projection_to_path_segment(
2128                        pb.map_bound(|pb| {
2129                            pb.with_self_ty(cx.tcx, cx.tcx.types.trait_object_dummy_self)
2130                                .projection_term
2131                        }),
2132                        cx,
2133                    ),
2134                    kind: AssocItemConstraintKind::Equality {
2135                        term: clean_middle_term(pb.map_bound(|pb| pb.term), cx),
2136                    },
2137                })
2138                .collect();
2139
2140            let late_bound_regions: FxIndexSet<_> = obj
2141                .iter()
2142                .flat_map(|pred| pred.bound_vars())
2143                .filter_map(|var| match var {
2144                    ty::BoundVariableKind::Region(ty::BoundRegionKind::Named(def_id)) => {
2145                        let name = cx.tcx.item_name(def_id);
2146                        if name != kw::UnderscoreLifetime {
2147                            Some(GenericParamDef::lifetime(def_id, name))
2148                        } else {
2149                            None
2150                        }
2151                    }
2152                    _ => None,
2153                })
2154                .collect();
2155            let late_bound_regions = late_bound_regions.into_iter().collect();
2156
2157            let path = clean_middle_path(cx, did, false, constraints, args);
2158            bounds.insert(0, PolyTrait { trait_: path, generic_params: late_bound_regions });
2159
2160            DynTrait(bounds, lifetime)
2161        }
2162        ty::Tuple(t) => {
2163            Tuple(t.iter().map(|t| clean_middle_ty(bound_ty.rebind(t), cx, None, None)).collect())
2164        }
2165
2166        ty::Alias(ty::Projection, alias_ty @ ty::AliasTy { def_id, args, .. }) => {
2167            if cx.tcx.is_impl_trait_in_trait(def_id) {
2168                clean_middle_opaque_bounds(cx, def_id, args)
2169            } else {
2170                Type::QPath(Box::new(clean_projection(
2171                    bound_ty.rebind(alias_ty.into()),
2172                    cx,
2173                    parent_def_id,
2174                )))
2175            }
2176        }
2177
2178        ty::Alias(ty::Inherent, alias_ty @ ty::AliasTy { def_id, .. }) => {
2179            let alias_ty = bound_ty.rebind(alias_ty);
2180            let self_type = clean_middle_ty(alias_ty.map_bound(|ty| ty.self_ty()), cx, None, None);
2181
2182            Type::QPath(Box::new(QPathData {
2183                assoc: PathSegment {
2184                    name: cx.tcx.item_name(def_id),
2185                    args: GenericArgs::AngleBracketed {
2186                        args: clean_middle_generic_args(
2187                            cx,
2188                            alias_ty.map_bound(|ty| ty.args.as_slice()),
2189                            true,
2190                            def_id,
2191                        ),
2192                        constraints: Default::default(),
2193                    },
2194                },
2195                should_fully_qualify: false,
2196                self_type,
2197                trait_: None,
2198            }))
2199        }
2200
2201        ty::Alias(ty::Free, ty::AliasTy { def_id, args, .. }) => {
2202            if cx.tcx.features().lazy_type_alias() {
2203                // Free type alias `data` represents the `type X` in `type X = Y`. If we need `Y`,
2204                // we need to use `type_of`.
2205                let path =
2206                    clean_middle_path(cx, def_id, false, ThinVec::new(), bound_ty.rebind(args));
2207                Type::Path { path }
2208            } else {
2209                let ty = cx.tcx.type_of(def_id).instantiate(cx.tcx, args);
2210                clean_middle_ty(bound_ty.rebind(ty), cx, None, None)
2211            }
2212        }
2213
2214        ty::Param(ref p) => {
2215            if let Some(bounds) = cx.impl_trait_bounds.remove(&p.index.into()) {
2216                ImplTrait(bounds)
2217            } else if p.name == kw::SelfUpper {
2218                SelfTy
2219            } else {
2220                Generic(p.name)
2221            }
2222        }
2223
2224        ty::Bound(_, ref ty) => match ty.kind {
2225            ty::BoundTyKind::Param(def_id) => Generic(cx.tcx.item_name(def_id)),
2226            ty::BoundTyKind::Anon => panic!("unexpected anonymous bound type variable"),
2227        },
2228
2229        ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
2230            // If it's already in the same alias, don't get an infinite loop.
2231            if cx.current_type_aliases.contains_key(&def_id) {
2232                let path =
2233                    clean_middle_path(cx, def_id, false, ThinVec::new(), bound_ty.rebind(args));
2234                Type::Path { path }
2235            } else {
2236                *cx.current_type_aliases.entry(def_id).or_insert(0) += 1;
2237                // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
2238                // by looking up the bounds associated with the def_id.
2239                let ty = clean_middle_opaque_bounds(cx, def_id, args);
2240                if let Some(count) = cx.current_type_aliases.get_mut(&def_id) {
2241                    *count -= 1;
2242                    if *count == 0 {
2243                        cx.current_type_aliases.remove(&def_id);
2244                    }
2245                }
2246                ty
2247            }
2248        }
2249
2250        ty::Closure(..) => panic!("Closure"),
2251        ty::CoroutineClosure(..) => panic!("CoroutineClosure"),
2252        ty::Coroutine(..) => panic!("Coroutine"),
2253        ty::Placeholder(..) => panic!("Placeholder"),
2254        ty::CoroutineWitness(..) => panic!("CoroutineWitness"),
2255        ty::Infer(..) => panic!("Infer"),
2256
2257        ty::Error(_) => FatalError.raise(),
2258    }
2259}
2260
2261fn clean_middle_opaque_bounds<'tcx>(
2262    cx: &mut DocContext<'tcx>,
2263    impl_trait_def_id: DefId,
2264    args: ty::GenericArgsRef<'tcx>,
2265) -> Type {
2266    let mut has_sized = false;
2267
2268    let bounds: Vec<_> = cx
2269        .tcx
2270        .explicit_item_bounds(impl_trait_def_id)
2271        .iter_instantiated_copied(cx.tcx, args)
2272        .collect();
2273
2274    let mut bounds = bounds
2275        .iter()
2276        .filter_map(|(bound, _)| {
2277            let bound_predicate = bound.kind();
2278            let trait_ref = match bound_predicate.skip_binder() {
2279                ty::ClauseKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
2280                ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
2281                    return clean_middle_region(reg, cx).map(GenericBound::Outlives);
2282                }
2283                _ => return None,
2284            };
2285
2286            // FIXME(sized-hierarchy): Always skip `MetaSized` bounds so that only `?Sized`
2287            // is shown and none of the new sizedness traits leak into documentation.
2288            if cx.tcx.is_lang_item(trait_ref.def_id(), LangItem::MetaSized) {
2289                return None;
2290            }
2291
2292            if let Some(sized) = cx.tcx.lang_items().sized_trait()
2293                && trait_ref.def_id() == sized
2294            {
2295                has_sized = true;
2296                return None;
2297            }
2298
2299            let bindings: ThinVec<_> = bounds
2300                .iter()
2301                .filter_map(|(bound, _)| {
2302                    let bound = bound.kind();
2303                    if let ty::ClauseKind::Projection(proj_pred) = bound.skip_binder()
2304                        && proj_pred.projection_term.trait_ref(cx.tcx) == trait_ref.skip_binder()
2305                    {
2306                        return Some(AssocItemConstraint {
2307                            assoc: projection_to_path_segment(
2308                                bound.rebind(proj_pred.projection_term),
2309                                cx,
2310                            ),
2311                            kind: AssocItemConstraintKind::Equality {
2312                                term: clean_middle_term(bound.rebind(proj_pred.term), cx),
2313                            },
2314                        });
2315                    }
2316                    None
2317                })
2318                .collect();
2319
2320            Some(clean_poly_trait_ref_with_constraints(cx, trait_ref, bindings))
2321        })
2322        .collect::<Vec<_>>();
2323
2324    if !has_sized {
2325        bounds.push(GenericBound::maybe_sized(cx));
2326    }
2327
2328    // Move trait bounds to the front.
2329    bounds.sort_by_key(|b| !b.is_trait_bound());
2330
2331    // Add back a `Sized` bound if there are no *trait* bounds remaining (incl. `?Sized`).
2332    // Since all potential trait bounds are at the front we can just check the first bound.
2333    if bounds.first().is_none_or(|b| !b.is_trait_bound()) {
2334        bounds.insert(0, GenericBound::sized(cx));
2335    }
2336
2337    if let Some(args) = cx.tcx.rendered_precise_capturing_args(impl_trait_def_id) {
2338        bounds.push(GenericBound::Use(
2339            args.iter()
2340                .map(|arg| match arg {
2341                    hir::PreciseCapturingArgKind::Lifetime(lt) => {
2342                        PreciseCapturingArg::Lifetime(Lifetime(*lt))
2343                    }
2344                    hir::PreciseCapturingArgKind::Param(param) => {
2345                        PreciseCapturingArg::Param(*param)
2346                    }
2347                })
2348                .collect(),
2349        ));
2350    }
2351
2352    ImplTrait(bounds)
2353}
2354
2355pub(crate) fn clean_field<'tcx>(field: &hir::FieldDef<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
2356    clean_field_with_def_id(field.def_id.to_def_id(), field.ident.name, clean_ty(field.ty, cx), cx)
2357}
2358
2359pub(crate) fn clean_middle_field(field: &ty::FieldDef, cx: &mut DocContext<'_>) -> Item {
2360    clean_field_with_def_id(
2361        field.did,
2362        field.name,
2363        clean_middle_ty(
2364            ty::Binder::dummy(cx.tcx.type_of(field.did).instantiate_identity()),
2365            cx,
2366            Some(field.did),
2367            None,
2368        ),
2369        cx,
2370    )
2371}
2372
2373pub(crate) fn clean_field_with_def_id(
2374    def_id: DefId,
2375    name: Symbol,
2376    ty: Type,
2377    cx: &mut DocContext<'_>,
2378) -> Item {
2379    Item::from_def_id_and_parts(def_id, Some(name), StructFieldItem(ty), cx)
2380}
2381
2382pub(crate) fn clean_variant_def(variant: &ty::VariantDef, cx: &mut DocContext<'_>) -> Item {
2383    let discriminant = match variant.discr {
2384        ty::VariantDiscr::Explicit(def_id) => Some(Discriminant { expr: None, value: def_id }),
2385        ty::VariantDiscr::Relative(_) => None,
2386    };
2387
2388    let kind = match variant.ctor_kind() {
2389        Some(CtorKind::Const) => VariantKind::CLike,
2390        Some(CtorKind::Fn) => VariantKind::Tuple(
2391            variant.fields.iter().map(|field| clean_middle_field(field, cx)).collect(),
2392        ),
2393        None => VariantKind::Struct(VariantStruct {
2394            fields: variant.fields.iter().map(|field| clean_middle_field(field, cx)).collect(),
2395        }),
2396    };
2397
2398    Item::from_def_id_and_parts(
2399        variant.def_id,
2400        Some(variant.name),
2401        VariantItem(Variant { kind, discriminant }),
2402        cx,
2403    )
2404}
2405
2406pub(crate) fn clean_variant_def_with_args<'tcx>(
2407    variant: &ty::VariantDef,
2408    args: &GenericArgsRef<'tcx>,
2409    cx: &mut DocContext<'tcx>,
2410) -> Item {
2411    let discriminant = match variant.discr {
2412        ty::VariantDiscr::Explicit(def_id) => Some(Discriminant { expr: None, value: def_id }),
2413        ty::VariantDiscr::Relative(_) => None,
2414    };
2415
2416    use rustc_middle::traits::ObligationCause;
2417    use rustc_trait_selection::infer::TyCtxtInferExt;
2418    use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
2419
2420    let infcx = cx.tcx.infer_ctxt().build(TypingMode::non_body_analysis());
2421    let kind = match variant.ctor_kind() {
2422        Some(CtorKind::Const) => VariantKind::CLike,
2423        Some(CtorKind::Fn) => VariantKind::Tuple(
2424            variant
2425                .fields
2426                .iter()
2427                .map(|field| {
2428                    let ty = cx.tcx.type_of(field.did).instantiate(cx.tcx, args);
2429
2430                    // normalize the type to only show concrete types
2431                    // note: we do not use try_normalize_erasing_regions since we
2432                    // do care about showing the regions
2433                    let ty = infcx
2434                        .at(&ObligationCause::dummy(), cx.param_env)
2435                        .query_normalize(ty)
2436                        .map(|normalized| normalized.value)
2437                        .unwrap_or(ty);
2438
2439                    clean_field_with_def_id(
2440                        field.did,
2441                        field.name,
2442                        clean_middle_ty(ty::Binder::dummy(ty), cx, Some(field.did), None),
2443                        cx,
2444                    )
2445                })
2446                .collect(),
2447        ),
2448        None => VariantKind::Struct(VariantStruct {
2449            fields: variant
2450                .fields
2451                .iter()
2452                .map(|field| {
2453                    let ty = cx.tcx.type_of(field.did).instantiate(cx.tcx, args);
2454
2455                    // normalize the type to only show concrete types
2456                    // note: we do not use try_normalize_erasing_regions since we
2457                    // do care about showing the regions
2458                    let ty = infcx
2459                        .at(&ObligationCause::dummy(), cx.param_env)
2460                        .query_normalize(ty)
2461                        .map(|normalized| normalized.value)
2462                        .unwrap_or(ty);
2463
2464                    clean_field_with_def_id(
2465                        field.did,
2466                        field.name,
2467                        clean_middle_ty(ty::Binder::dummy(ty), cx, Some(field.did), None),
2468                        cx,
2469                    )
2470                })
2471                .collect(),
2472        }),
2473    };
2474
2475    Item::from_def_id_and_parts(
2476        variant.def_id,
2477        Some(variant.name),
2478        VariantItem(Variant { kind, discriminant }),
2479        cx,
2480    )
2481}
2482
2483fn clean_variant_data<'tcx>(
2484    variant: &hir::VariantData<'tcx>,
2485    disr_expr: &Option<&hir::AnonConst>,
2486    cx: &mut DocContext<'tcx>,
2487) -> Variant {
2488    let discriminant = disr_expr
2489        .map(|disr| Discriminant { expr: Some(disr.body), value: disr.def_id.to_def_id() });
2490
2491    let kind = match variant {
2492        hir::VariantData::Struct { fields, .. } => VariantKind::Struct(VariantStruct {
2493            fields: fields.iter().map(|x| clean_field(x, cx)).collect(),
2494        }),
2495        hir::VariantData::Tuple(..) => {
2496            VariantKind::Tuple(variant.fields().iter().map(|x| clean_field(x, cx)).collect())
2497        }
2498        hir::VariantData::Unit(..) => VariantKind::CLike,
2499    };
2500
2501    Variant { discriminant, kind }
2502}
2503
2504fn clean_path<'tcx>(path: &hir::Path<'tcx>, cx: &mut DocContext<'tcx>) -> Path {
2505    Path {
2506        res: path.res,
2507        segments: path.segments.iter().map(|x| clean_path_segment(x, cx)).collect(),
2508    }
2509}
2510
2511fn clean_generic_args<'tcx>(
2512    generic_args: &hir::GenericArgs<'tcx>,
2513    cx: &mut DocContext<'tcx>,
2514) -> GenericArgs {
2515    match generic_args.parenthesized {
2516        hir::GenericArgsParentheses::No => {
2517            let args = generic_args
2518                .args
2519                .iter()
2520                .map(|arg| match arg {
2521                    hir::GenericArg::Lifetime(lt) if !lt.is_anonymous() => {
2522                        GenericArg::Lifetime(clean_lifetime(lt, cx))
2523                    }
2524                    hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
2525                    hir::GenericArg::Type(ty) => GenericArg::Type(clean_ty(ty.as_unambig_ty(), cx)),
2526                    hir::GenericArg::Const(ct) => {
2527                        GenericArg::Const(Box::new(clean_const(ct.as_unambig_ct(), cx)))
2528                    }
2529                    hir::GenericArg::Infer(_inf) => GenericArg::Infer,
2530                })
2531                .collect();
2532            let constraints = generic_args
2533                .constraints
2534                .iter()
2535                .map(|c| clean_assoc_item_constraint(c, cx))
2536                .collect::<ThinVec<_>>();
2537            GenericArgs::AngleBracketed { args, constraints }
2538        }
2539        hir::GenericArgsParentheses::ParenSugar => {
2540            let Some((inputs, output)) = generic_args.paren_sugar_inputs_output() else {
2541                bug!();
2542            };
2543            let inputs = inputs.iter().map(|x| clean_ty(x, cx)).collect();
2544            let output = match output.kind {
2545                hir::TyKind::Tup(&[]) => None,
2546                _ => Some(Box::new(clean_ty(output, cx))),
2547            };
2548            GenericArgs::Parenthesized { inputs, output }
2549        }
2550        hir::GenericArgsParentheses::ReturnTypeNotation => GenericArgs::ReturnTypeNotation,
2551    }
2552}
2553
2554fn clean_path_segment<'tcx>(
2555    path: &hir::PathSegment<'tcx>,
2556    cx: &mut DocContext<'tcx>,
2557) -> PathSegment {
2558    PathSegment { name: path.ident.name, args: clean_generic_args(path.args(), cx) }
2559}
2560
2561fn clean_bare_fn_ty<'tcx>(
2562    bare_fn: &hir::FnPtrTy<'tcx>,
2563    cx: &mut DocContext<'tcx>,
2564) -> BareFunctionDecl {
2565    let (generic_params, decl) = enter_impl_trait(cx, |cx| {
2566        // NOTE: Generics must be cleaned before params.
2567        let generic_params = bare_fn
2568            .generic_params
2569            .iter()
2570            .filter(|p| !is_elided_lifetime(p))
2571            .map(|x| clean_generic_param(cx, None, x))
2572            .collect();
2573        // Since it's more conventional stylistically, elide the name of all params called `_`
2574        // unless there's at least one interestingly named param in which case don't elide any
2575        // name since mixing named and unnamed params is less legible.
2576        let filter = |ident: Option<Ident>| {
2577            ident.map(|ident| ident.name).filter(|&ident| ident != kw::Underscore)
2578        };
2579        let fallback =
2580            bare_fn.param_idents.iter().copied().find_map(filter).map(|_| kw::Underscore);
2581        let params = clean_params(cx, bare_fn.decl.inputs, bare_fn.param_idents, |ident| {
2582            filter(ident).or(fallback)
2583        });
2584        let decl = clean_fn_decl_with_params(cx, bare_fn.decl, None, params);
2585        (generic_params, decl)
2586    });
2587    BareFunctionDecl { safety: bare_fn.safety, abi: bare_fn.abi, decl, generic_params }
2588}
2589
2590fn clean_unsafe_binder_ty<'tcx>(
2591    unsafe_binder_ty: &hir::UnsafeBinderTy<'tcx>,
2592    cx: &mut DocContext<'tcx>,
2593) -> UnsafeBinderTy {
2594    let generic_params = unsafe_binder_ty
2595        .generic_params
2596        .iter()
2597        .filter(|p| !is_elided_lifetime(p))
2598        .map(|x| clean_generic_param(cx, None, x))
2599        .collect();
2600    let ty = clean_ty(unsafe_binder_ty.inner_ty, cx);
2601    UnsafeBinderTy { generic_params, ty }
2602}
2603
2604pub(crate) fn reexport_chain(
2605    tcx: TyCtxt<'_>,
2606    import_def_id: LocalDefId,
2607    target_def_id: DefId,
2608) -> &[Reexport] {
2609    for child in tcx.module_children_local(tcx.local_parent(import_def_id)) {
2610        if child.res.opt_def_id() == Some(target_def_id)
2611            && child.reexport_chain.first().and_then(|r| r.id()) == Some(import_def_id.to_def_id())
2612        {
2613            return &child.reexport_chain;
2614        }
2615    }
2616    &[]
2617}
2618
2619/// Collect attributes from the whole import chain.
2620fn get_all_import_attributes<'hir>(
2621    cx: &mut DocContext<'hir>,
2622    import_def_id: LocalDefId,
2623    target_def_id: DefId,
2624    is_inline: bool,
2625) -> Vec<(Cow<'hir, hir::Attribute>, Option<DefId>)> {
2626    let mut attrs = Vec::new();
2627    let mut first = true;
2628    for def_id in reexport_chain(cx.tcx, import_def_id, target_def_id)
2629        .iter()
2630        .flat_map(|reexport| reexport.id())
2631    {
2632        let import_attrs = inline::load_attrs(cx, def_id);
2633        if first {
2634            // This is the "original" reexport so we get all its attributes without filtering them.
2635            attrs = import_attrs.iter().map(|attr| (Cow::Borrowed(attr), Some(def_id))).collect();
2636            first = false;
2637        // We don't add attributes of an intermediate re-export if it has `#[doc(hidden)]`.
2638        } else if cx.render_options.document_hidden || !cx.tcx.is_doc_hidden(def_id) {
2639            add_without_unwanted_attributes(&mut attrs, import_attrs, is_inline, Some(def_id));
2640        }
2641    }
2642    attrs
2643}
2644
2645fn filter_tokens_from_list(
2646    args_tokens: &TokenStream,
2647    should_retain: impl Fn(&TokenTree) -> bool,
2648) -> Vec<TokenTree> {
2649    let mut tokens = Vec::with_capacity(args_tokens.len());
2650    let mut skip_next_comma = false;
2651    for token in args_tokens.iter() {
2652        match token {
2653            TokenTree::Token(Token { kind: TokenKind::Comma, .. }, _) if skip_next_comma => {
2654                skip_next_comma = false;
2655            }
2656            token if should_retain(token) => {
2657                skip_next_comma = false;
2658                tokens.push(token.clone());
2659            }
2660            _ => {
2661                skip_next_comma = true;
2662            }
2663        }
2664    }
2665    tokens
2666}
2667
2668fn filter_doc_attr_ident(ident: Symbol, is_inline: bool) -> bool {
2669    if is_inline {
2670        ident == sym::hidden || ident == sym::inline || ident == sym::no_inline
2671    } else {
2672        ident == sym::cfg
2673    }
2674}
2675
2676/// Remove attributes from `normal` that should not be inherited by `use` re-export.
2677/// Before calling this function, make sure `normal` is a `#[doc]` attribute.
2678fn filter_doc_attr(args: &mut hir::AttrArgs, is_inline: bool) {
2679    match args {
2680        hir::AttrArgs::Delimited(args) => {
2681            let tokens = filter_tokens_from_list(&args.tokens, |token| {
2682                !matches!(
2683                    token,
2684                    TokenTree::Token(
2685                        Token {
2686                            kind: TokenKind::Ident(
2687                                ident,
2688                                _,
2689                            ),
2690                            ..
2691                        },
2692                        _,
2693                    ) if filter_doc_attr_ident(*ident, is_inline),
2694                )
2695            });
2696            args.tokens = TokenStream::new(tokens);
2697        }
2698        hir::AttrArgs::Empty | hir::AttrArgs::Eq { .. } => {}
2699    }
2700}
2701
2702/// When inlining items, we merge their attributes (and all the reexports attributes too) with the
2703/// final reexport. For example:
2704///
2705/// ```ignore (just an example)
2706/// #[doc(hidden, cfg(feature = "foo"))]
2707/// pub struct Foo;
2708///
2709/// #[doc(cfg(feature = "bar"))]
2710/// #[doc(hidden, no_inline)]
2711/// pub use Foo as Foo1;
2712///
2713/// #[doc(inline)]
2714/// pub use Foo2 as Bar;
2715/// ```
2716///
2717/// So `Bar` at the end will have both `cfg(feature = "...")`. However, we don't want to merge all
2718/// attributes so we filter out the following ones:
2719/// * `doc(inline)`
2720/// * `doc(no_inline)`
2721/// * `doc(hidden)`
2722fn add_without_unwanted_attributes<'hir>(
2723    attrs: &mut Vec<(Cow<'hir, hir::Attribute>, Option<DefId>)>,
2724    new_attrs: &'hir [hir::Attribute],
2725    is_inline: bool,
2726    import_parent: Option<DefId>,
2727) {
2728    for attr in new_attrs {
2729        if attr.is_doc_comment() {
2730            attrs.push((Cow::Borrowed(attr), import_parent));
2731            continue;
2732        }
2733        let mut attr = attr.clone();
2734        match attr {
2735            hir::Attribute::Unparsed(ref mut normal) if let [ident] = &*normal.path.segments => {
2736                let ident = ident.name;
2737                if ident == sym::doc {
2738                    filter_doc_attr(&mut normal.args, is_inline);
2739                    attrs.push((Cow::Owned(attr), import_parent));
2740                } else if is_inline || ident != sym::cfg_trace {
2741                    // If it's not a `cfg()` attribute, we keep it.
2742                    attrs.push((Cow::Owned(attr), import_parent));
2743                }
2744            }
2745            // FIXME: make sure to exclude `#[cfg_trace]` here when it is ported to the new parsers
2746            hir::Attribute::Parsed(..) => {
2747                attrs.push((Cow::Owned(attr), import_parent));
2748            }
2749            _ => {}
2750        }
2751    }
2752}
2753
2754fn clean_maybe_renamed_item<'tcx>(
2755    cx: &mut DocContext<'tcx>,
2756    item: &hir::Item<'tcx>,
2757    renamed: Option<Symbol>,
2758    import_ids: &[LocalDefId],
2759) -> Vec<Item> {
2760    use hir::ItemKind;
2761    fn get_name(
2762        cx: &DocContext<'_>,
2763        item: &hir::Item<'_>,
2764        renamed: Option<Symbol>,
2765    ) -> Option<Symbol> {
2766        renamed.or_else(|| cx.tcx.hir_opt_name(item.hir_id()))
2767    }
2768
2769    let def_id = item.owner_id.to_def_id();
2770    cx.with_param_env(def_id, |cx| {
2771        // These kinds of item either don't need a `name` or accept a `None` one so we handle them
2772        // before.
2773        match item.kind {
2774            ItemKind::Impl(ref impl_) => return clean_impl(impl_, item.owner_id.def_id, cx),
2775            ItemKind::Use(path, kind) => {
2776                return clean_use_statement(
2777                    item,
2778                    get_name(cx, item, renamed),
2779                    path,
2780                    kind,
2781                    cx,
2782                    &mut FxHashSet::default(),
2783                );
2784            }
2785            _ => {}
2786        }
2787
2788        let mut name = get_name(cx, item, renamed).unwrap();
2789
2790        let kind = match item.kind {
2791            ItemKind::Static(mutability, _, ty, body_id) => StaticItem(Static {
2792                type_: Box::new(clean_ty(ty, cx)),
2793                mutability,
2794                expr: Some(body_id),
2795            }),
2796            ItemKind::Const(_, generics, ty, body_id) => ConstantItem(Box::new(Constant {
2797                generics: clean_generics(generics, cx),
2798                type_: clean_ty(ty, cx),
2799                kind: ConstantKind::Local { body: body_id, def_id },
2800            })),
2801            ItemKind::TyAlias(_, generics, ty) => {
2802                *cx.current_type_aliases.entry(def_id).or_insert(0) += 1;
2803                let rustdoc_ty = clean_ty(ty, cx);
2804                let type_ =
2805                    clean_middle_ty(ty::Binder::dummy(lower_ty(cx.tcx, ty)), cx, None, None);
2806                let generics = clean_generics(generics, cx);
2807                if let Some(count) = cx.current_type_aliases.get_mut(&def_id) {
2808                    *count -= 1;
2809                    if *count == 0 {
2810                        cx.current_type_aliases.remove(&def_id);
2811                    }
2812                }
2813
2814                let ty = cx.tcx.type_of(def_id).instantiate_identity();
2815
2816                let mut ret = Vec::new();
2817                let inner_type = clean_ty_alias_inner_type(ty, cx, &mut ret);
2818
2819                ret.push(generate_item_with_correct_attrs(
2820                    cx,
2821                    TypeAliasItem(Box::new(TypeAlias {
2822                        generics,
2823                        inner_type,
2824                        type_: rustdoc_ty,
2825                        item_type: Some(type_),
2826                    })),
2827                    item.owner_id.def_id.to_def_id(),
2828                    name,
2829                    import_ids,
2830                    renamed,
2831                ));
2832                return ret;
2833            }
2834            ItemKind::Enum(_, generics, def) => EnumItem(Enum {
2835                variants: def.variants.iter().map(|v| clean_variant(v, cx)).collect(),
2836                generics: clean_generics(generics, cx),
2837            }),
2838            ItemKind::TraitAlias(_, generics, bounds) => TraitAliasItem(TraitAlias {
2839                generics: clean_generics(generics, cx),
2840                bounds: bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
2841            }),
2842            ItemKind::Union(_, generics, variant_data) => UnionItem(Union {
2843                generics: clean_generics(generics, cx),
2844                fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
2845            }),
2846            ItemKind::Struct(_, generics, variant_data) => StructItem(Struct {
2847                ctor_kind: variant_data.ctor_kind(),
2848                generics: clean_generics(generics, cx),
2849                fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
2850            }),
2851            // FIXME: handle attributes and derives that aren't proc macros, and macros with
2852            // multiple kinds
2853            ItemKind::Macro(_, macro_def, MacroKinds::BANG) => MacroItem(Macro {
2854                source: display_macro_source(cx, name, macro_def),
2855                macro_rules: macro_def.macro_rules,
2856            }),
2857            ItemKind::Macro(_, _, MacroKinds::ATTR) => {
2858                clean_proc_macro(item, &mut name, MacroKind::Attr, cx)
2859            }
2860            ItemKind::Macro(_, _, MacroKinds::DERIVE) => {
2861                clean_proc_macro(item, &mut name, MacroKind::Derive, cx)
2862            }
2863            ItemKind::Macro(_, _, _) => todo!("Handle macros with multiple kinds"),
2864            // proc macros can have a name set by attributes
2865            ItemKind::Fn { ref sig, generics, body: body_id, .. } => {
2866                clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
2867            }
2868            ItemKind::Trait(_, _, _, _, generics, bounds, item_ids) => {
2869                let items = item_ids
2870                    .iter()
2871                    .map(|&ti| clean_trait_item(cx.tcx.hir_trait_item(ti), cx))
2872                    .collect();
2873
2874                TraitItem(Box::new(Trait {
2875                    def_id,
2876                    items,
2877                    generics: clean_generics(generics, cx),
2878                    bounds: bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
2879                }))
2880            }
2881            ItemKind::ExternCrate(orig_name, _) => {
2882                return clean_extern_crate(item, name, orig_name, cx);
2883            }
2884            _ => span_bug!(item.span, "not yet converted"),
2885        };
2886
2887        vec![generate_item_with_correct_attrs(
2888            cx,
2889            kind,
2890            item.owner_id.def_id.to_def_id(),
2891            name,
2892            import_ids,
2893            renamed,
2894        )]
2895    })
2896}
2897
2898fn clean_variant<'tcx>(variant: &hir::Variant<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
2899    let kind = VariantItem(clean_variant_data(&variant.data, &variant.disr_expr, cx));
2900    Item::from_def_id_and_parts(variant.def_id.to_def_id(), Some(variant.ident.name), kind, cx)
2901}
2902
2903fn clean_impl<'tcx>(
2904    impl_: &hir::Impl<'tcx>,
2905    def_id: LocalDefId,
2906    cx: &mut DocContext<'tcx>,
2907) -> Vec<Item> {
2908    let tcx = cx.tcx;
2909    let mut ret = Vec::new();
2910    let trait_ = impl_.of_trait.map(|t| clean_trait_ref(&t.trait_ref, cx));
2911    let items = impl_
2912        .items
2913        .iter()
2914        .map(|&ii| clean_impl_item(tcx.hir_impl_item(ii), cx))
2915        .collect::<Vec<_>>();
2916
2917    // If this impl block is an implementation of the Deref trait, then we
2918    // need to try inlining the target's inherent impl blocks as well.
2919    if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
2920        build_deref_target_impls(cx, &items, &mut ret);
2921    }
2922
2923    let for_ = clean_ty(impl_.self_ty, cx);
2924    let type_alias =
2925        for_.def_id(&cx.cache).and_then(|alias_def_id: DefId| match tcx.def_kind(alias_def_id) {
2926            DefKind::TyAlias => Some(clean_middle_ty(
2927                ty::Binder::dummy(tcx.type_of(def_id).instantiate_identity()),
2928                cx,
2929                Some(def_id.to_def_id()),
2930                None,
2931            )),
2932            _ => None,
2933        });
2934    let mut make_item = |trait_: Option<Path>, for_: Type, items: Vec<Item>| {
2935        let kind = ImplItem(Box::new(Impl {
2936            safety: match impl_.of_trait {
2937                Some(of_trait) => of_trait.safety,
2938                None => hir::Safety::Safe,
2939            },
2940            generics: clean_generics(impl_.generics, cx),
2941            trait_,
2942            for_,
2943            items,
2944            polarity: tcx.impl_polarity(def_id),
2945            kind: if utils::has_doc_flag(tcx, def_id.to_def_id(), sym::fake_variadic) {
2946                ImplKind::FakeVariadic
2947            } else {
2948                ImplKind::Normal
2949            },
2950        }));
2951        Item::from_def_id_and_parts(def_id.to_def_id(), None, kind, cx)
2952    };
2953    if let Some(type_alias) = type_alias {
2954        ret.push(make_item(trait_.clone(), type_alias, items.clone()));
2955    }
2956    ret.push(make_item(trait_, for_, items));
2957    ret
2958}
2959
2960fn clean_extern_crate<'tcx>(
2961    krate: &hir::Item<'tcx>,
2962    name: Symbol,
2963    orig_name: Option<Symbol>,
2964    cx: &mut DocContext<'tcx>,
2965) -> Vec<Item> {
2966    // this is the ID of the `extern crate` statement
2967    let cnum = cx.tcx.extern_mod_stmt_cnum(krate.owner_id.def_id).unwrap_or(LOCAL_CRATE);
2968    // this is the ID of the crate itself
2969    let crate_def_id = cnum.as_def_id();
2970    let attrs = cx.tcx.hir_attrs(krate.hir_id());
2971    let ty_vis = cx.tcx.visibility(krate.owner_id);
2972    let please_inline = ty_vis.is_public()
2973        && attrs.iter().any(|a| {
2974            a.has_name(sym::doc)
2975                && match a.meta_item_list() {
2976                    Some(l) => ast::attr::list_contains_name(&l, sym::inline),
2977                    None => false,
2978                }
2979        })
2980        && !cx.is_json_output();
2981
2982    let krate_owner_def_id = krate.owner_id.def_id;
2983
2984    if please_inline
2985        && let Some(items) = inline::try_inline(
2986            cx,
2987            Res::Def(DefKind::Mod, crate_def_id),
2988            name,
2989            Some((attrs, Some(krate_owner_def_id))),
2990            &mut Default::default(),
2991        )
2992    {
2993        return items;
2994    }
2995
2996    vec![Item::from_def_id_and_parts(
2997        krate_owner_def_id.to_def_id(),
2998        Some(name),
2999        ExternCrateItem { src: orig_name },
3000        cx,
3001    )]
3002}
3003
3004fn clean_use_statement<'tcx>(
3005    import: &hir::Item<'tcx>,
3006    name: Option<Symbol>,
3007    path: &hir::UsePath<'tcx>,
3008    kind: hir::UseKind,
3009    cx: &mut DocContext<'tcx>,
3010    inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
3011) -> Vec<Item> {
3012    let mut items = Vec::new();
3013    let hir::UsePath { segments, ref res, span } = *path;
3014    for res in res.present_items() {
3015        let path = hir::Path { segments, res, span };
3016        items.append(&mut clean_use_statement_inner(import, name, &path, kind, cx, inlined_names));
3017    }
3018    items
3019}
3020
3021fn clean_use_statement_inner<'tcx>(
3022    import: &hir::Item<'tcx>,
3023    name: Option<Symbol>,
3024    path: &hir::Path<'tcx>,
3025    kind: hir::UseKind,
3026    cx: &mut DocContext<'tcx>,
3027    inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
3028) -> Vec<Item> {
3029    if should_ignore_res(path.res) {
3030        return Vec::new();
3031    }
3032    // We need this comparison because some imports (for std types for example)
3033    // are "inserted" as well but directly by the compiler and they should not be
3034    // taken into account.
3035    if import.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
3036        return Vec::new();
3037    }
3038
3039    let visibility = cx.tcx.visibility(import.owner_id);
3040    let attrs = cx.tcx.hir_attrs(import.hir_id());
3041    let inline_attr = hir_attr_lists(attrs, sym::doc).get_word_attr(sym::inline);
3042    let pub_underscore = visibility.is_public() && name == Some(kw::Underscore);
3043    let current_mod = cx.tcx.parent_module_from_def_id(import.owner_id.def_id);
3044    let import_def_id = import.owner_id.def_id;
3045
3046    // The parent of the module in which this import resides. This
3047    // is the same as `current_mod` if that's already the top
3048    // level module.
3049    let parent_mod = cx.tcx.parent_module_from_def_id(current_mod.to_local_def_id());
3050
3051    // This checks if the import can be seen from a higher level module.
3052    // In other words, it checks if the visibility is the equivalent of
3053    // `pub(super)` or higher. If the current module is the top level
3054    // module, there isn't really a parent module, which makes the results
3055    // meaningless. In this case, we make sure the answer is `false`.
3056    let is_visible_from_parent_mod =
3057        visibility.is_accessible_from(parent_mod, cx.tcx) && !current_mod.is_top_level_module();
3058
3059    if pub_underscore && let Some(ref inline) = inline_attr {
3060        struct_span_code_err!(
3061            cx.tcx.dcx(),
3062            inline.span(),
3063            E0780,
3064            "anonymous imports cannot be inlined"
3065        )
3066        .with_span_label(import.span, "anonymous import")
3067        .emit();
3068    }
3069
3070    // We consider inlining the documentation of `pub use` statements, but we
3071    // forcefully don't inline if this is not public or if the
3072    // #[doc(no_inline)] attribute is present.
3073    // Don't inline doc(hidden) imports so they can be stripped at a later stage.
3074    let mut denied = cx.is_json_output()
3075        || !(visibility.is_public()
3076            || (cx.render_options.document_private && is_visible_from_parent_mod))
3077        || pub_underscore
3078        || attrs.iter().any(|a| {
3079            a.has_name(sym::doc)
3080                && match a.meta_item_list() {
3081                    Some(l) => {
3082                        ast::attr::list_contains_name(&l, sym::no_inline)
3083                            || ast::attr::list_contains_name(&l, sym::hidden)
3084                    }
3085                    None => false,
3086                }
3087        });
3088
3089    // Also check whether imports were asked to be inlined, in case we're trying to re-export a
3090    // crate in Rust 2018+
3091    let path = clean_path(path, cx);
3092    let inner = if kind == hir::UseKind::Glob {
3093        if !denied {
3094            let mut visited = DefIdSet::default();
3095            if let Some(items) = inline::try_inline_glob(
3096                cx,
3097                path.res,
3098                current_mod,
3099                &mut visited,
3100                inlined_names,
3101                import,
3102            ) {
3103                return items;
3104            }
3105        }
3106        Import::new_glob(resolve_use_source(cx, path), true)
3107    } else {
3108        let name = name.unwrap();
3109        if inline_attr.is_none()
3110            && let Res::Def(DefKind::Mod, did) = path.res
3111            && !did.is_local()
3112            && did.is_crate_root()
3113        {
3114            // if we're `pub use`ing an extern crate root, don't inline it unless we
3115            // were specifically asked for it
3116            denied = true;
3117        }
3118        if !denied
3119            && let Some(mut items) = inline::try_inline(
3120                cx,
3121                path.res,
3122                name,
3123                Some((attrs, Some(import_def_id))),
3124                &mut Default::default(),
3125            )
3126        {
3127            items.push(Item::from_def_id_and_parts(
3128                import_def_id.to_def_id(),
3129                None,
3130                ImportItem(Import::new_simple(name, resolve_use_source(cx, path), false)),
3131                cx,
3132            ));
3133            return items;
3134        }
3135        Import::new_simple(name, resolve_use_source(cx, path), true)
3136    };
3137
3138    vec![Item::from_def_id_and_parts(import_def_id.to_def_id(), None, ImportItem(inner), cx)]
3139}
3140
3141fn clean_maybe_renamed_foreign_item<'tcx>(
3142    cx: &mut DocContext<'tcx>,
3143    item: &hir::ForeignItem<'tcx>,
3144    renamed: Option<Symbol>,
3145    import_id: Option<LocalDefId>,
3146) -> Item {
3147    let def_id = item.owner_id.to_def_id();
3148    cx.with_param_env(def_id, |cx| {
3149        let kind = match item.kind {
3150            hir::ForeignItemKind::Fn(sig, idents, generics) => ForeignFunctionItem(
3151                clean_function(cx, &sig, generics, ParamsSrc::Idents(idents)),
3152                sig.header.safety(),
3153            ),
3154            hir::ForeignItemKind::Static(ty, mutability, safety) => ForeignStaticItem(
3155                Static { type_: Box::new(clean_ty(ty, cx)), mutability, expr: None },
3156                safety,
3157            ),
3158            hir::ForeignItemKind::Type => ForeignTypeItem,
3159        };
3160
3161        generate_item_with_correct_attrs(
3162            cx,
3163            kind,
3164            item.owner_id.def_id.to_def_id(),
3165            item.ident.name,
3166            import_id.as_slice(),
3167            renamed,
3168        )
3169    })
3170}
3171
3172fn clean_assoc_item_constraint<'tcx>(
3173    constraint: &hir::AssocItemConstraint<'tcx>,
3174    cx: &mut DocContext<'tcx>,
3175) -> AssocItemConstraint {
3176    AssocItemConstraint {
3177        assoc: PathSegment {
3178            name: constraint.ident.name,
3179            args: clean_generic_args(constraint.gen_args, cx),
3180        },
3181        kind: match constraint.kind {
3182            hir::AssocItemConstraintKind::Equality { ref term } => {
3183                AssocItemConstraintKind::Equality { term: clean_hir_term(term, cx) }
3184            }
3185            hir::AssocItemConstraintKind::Bound { bounds } => AssocItemConstraintKind::Bound {
3186                bounds: bounds.iter().filter_map(|b| clean_generic_bound(b, cx)).collect(),
3187            },
3188        },
3189    }
3190}
3191
3192fn clean_bound_vars<'tcx>(
3193    bound_vars: &ty::List<ty::BoundVariableKind>,
3194    cx: &mut DocContext<'tcx>,
3195) -> Vec<GenericParamDef> {
3196    bound_vars
3197        .into_iter()
3198        .filter_map(|var| match var {
3199            ty::BoundVariableKind::Region(ty::BoundRegionKind::Named(def_id)) => {
3200                let name = cx.tcx.item_name(def_id);
3201                if name != kw::UnderscoreLifetime {
3202                    Some(GenericParamDef::lifetime(def_id, name))
3203                } else {
3204                    None
3205                }
3206            }
3207            ty::BoundVariableKind::Ty(ty::BoundTyKind::Param(def_id)) => {
3208                let name = cx.tcx.item_name(def_id);
3209                Some(GenericParamDef {
3210                    name,
3211                    def_id,
3212                    kind: GenericParamDefKind::Type {
3213                        bounds: ThinVec::new(),
3214                        default: None,
3215                        synthetic: false,
3216                    },
3217                })
3218            }
3219            // FIXME(non_lifetime_binders): Support higher-ranked const parameters.
3220            ty::BoundVariableKind::Const => None,
3221            _ => None,
3222        })
3223        .collect()
3224}