src/librustdoc/clean/mod.rs

   1 //! This module contains the "cleaned" pieces of the AST, and the functions
   2 //! that clean them.
   3
   4 mod auto_trait;
   5 mod blanket_impl;
   6 pub(crate) mod cfg;
   7 pub(crate) mod inline;
   8 mod render_macro_matchers;
   9 mod simplify;
  10 pub(crate) mod types;
  11 pub(crate) mod utils;
  12
  13 use rustc_ast as ast;
  14 use rustc_attr as attr;
  15 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  16 use rustc_hir as hir;
  17 use rustc_hir::def::{CtorKind, DefKind, Res};
  18 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
  19 use rustc_hir::PredicateOrigin;
  20 use rustc_infer::infer::region_constraints::{Constraint, RegionConstraintData};
  21 use rustc_middle::middle::resolve_lifetime as rl;
  22 use rustc_middle::ty::fold::TypeFolder;
  23 use rustc_middle::ty::subst::{InternalSubsts, Subst};
  24 use rustc_middle::ty::{self, AdtKind, DefIdTree, EarlyBinder, Lift, Ty, TyCtxt};
  25 use rustc_middle::{bug, span_bug};
  26 use rustc_span::hygiene::{AstPass, MacroKind};
  27 use rustc_span::symbol::{kw, sym, Ident, Symbol};
  28 use rustc_span::{self, ExpnKind};
  29 use rustc_typeck::hir_ty_to_ty;
  30
  31 use std::assert_matches::assert_matches;
  32 use std::collections::hash_map::Entry;
  33 use std::collections::BTreeMap;
  34 use std::default::Default;
  35 use std::hash::Hash;
  36 use std::{mem, vec};
  37
  38 use crate::core::{self, DocContext, ImplTraitParam};
  39 use crate::formats::item_type::ItemType;
  40 use crate::visit_ast::Module as DocModule;
  41
  42 use utils::*;
  43
  44 pub(crate) use self::types::*;
  45 pub(crate) use self::utils::{get_auto_trait_and_blanket_impls, krate, register_res};
  46
  47 pub(crate) trait Clean<'tcx, T> {
  48     fn clean(&self, cx: &mut DocContext<'tcx>) -> T;
  49 }
  50
  51 impl<'tcx> Clean<'tcx, Item> for DocModule<'tcx> {
  52     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
  53         let mut items: Vec<Item> = vec![];
  54         items.extend(
  55             self.foreigns
  56                 .iter()
  57                 .map(|(item, renamed)| clean_maybe_renamed_foreign_item(cx, item, *renamed)),
  58         );
  59         items.extend(self.mods.iter().map(|x| x.clean(cx)));
  60         items.extend(
  61             self.items
  62                 .iter()
  63                 .flat_map(|(item, renamed)| clean_maybe_renamed_item(cx, item, *renamed)),
  64         );
  65
  66         // determine if we should display the inner contents or
  67         // the outer `mod` item for the source code.
  68
  69         let span = Span::new({
  70             let where_outer = self.where_outer(cx.tcx);
  71             let sm = cx.sess().source_map();
  72             let outer = sm.lookup_char_pos(where_outer.lo());
  73             let inner = sm.lookup_char_pos(self.where_inner.lo());
  74             if outer.file.start_pos == inner.file.start_pos {
  75                 // mod foo { ... }
  76                 where_outer
  77             } else {
  78                 // mod foo; (and a separate SourceFile for the contents)
  79                 self.where_inner
  80             }
  81         });
  82
  83         Item::from_hir_id_and_parts(
  84             self.id,
  85             Some(self.name),
  86             ModuleItem(Module { items, span }),
  87             cx,
  88         )
  89     }
  90 }
  91
  92 impl<'tcx> Clean<'tcx, Attributes> for [ast::Attribute] {
  93     fn clean(&self, _cx: &mut DocContext<'_>) -> Attributes {
  94         Attributes::from_ast(self, None)
  95     }
  96 }
  97
  98 impl<'tcx> Clean<'tcx, Option<GenericBound>> for hir::GenericBound<'tcx> {
  99     fn clean(&self, cx: &mut DocContext<'tcx>) -> Option<GenericBound> {
 100         Some(match *self {
 101             hir::GenericBound::Outlives(lt) => GenericBound::Outlives(lt.clean(cx)),
 102             hir::GenericBound::LangItemTrait(lang_item, span, _, generic_args) => {
 103                 let def_id = cx.tcx.require_lang_item(lang_item, Some(span));
 104
 105                 let trait_ref = ty::TraitRef::identity(cx.tcx, def_id).skip_binder();
 106
 107                 let generic_args = generic_args.clean(cx);
 108                 let GenericArgs::AngleBracketed { bindings, .. } = generic_args
 109                 else {
 110                     bug!("clean: parenthesized `GenericBound::LangItemTrait`");
 111                 };
 112
 113                 let trait_ = clean_trait_ref_with_bindings(cx, trait_ref, &bindings);
 114                 GenericBound::TraitBound(
 115                     PolyTrait { trait_, generic_params: vec![] },
 116                     hir::TraitBoundModifier::None,
 117                 )
 118             }
 119             hir::GenericBound::Trait(ref t, modifier) => {
 120                 // `T: ~const Destruct` is hidden because `T: Destruct` is a no-op.
 121                 if modifier == hir::TraitBoundModifier::MaybeConst
 122                     && cx.tcx.lang_items().destruct_trait()
 123                         == Some(t.trait_ref.trait_def_id().unwrap())
 124                 {
 125                     return None;
 126                 }
 127
 128                 GenericBound::TraitBound(t.clean(cx), modifier)
 129             }
 130         })
 131     }
 132 }
 133
 134 fn clean_trait_ref_with_bindings<'tcx>(
 135     cx: &mut DocContext<'tcx>,
 136     trait_ref: ty::TraitRef<'tcx>,
 137     bindings: &[TypeBinding],
 138 ) -> Path {
 139     let kind = cx.tcx.def_kind(trait_ref.def_id).into();
 140     if !matches!(kind, ItemType::Trait | ItemType::TraitAlias) {
 141         span_bug!(cx.tcx.def_span(trait_ref.def_id), "`TraitRef` had unexpected kind {:?}", kind);
 142     }
 143     inline::record_extern_fqn(cx, trait_ref.def_id, kind);
 144     let path = external_path(cx, trait_ref.def_id, true, bindings.to_vec(), trait_ref.substs);
 145
 146     debug!("ty::TraitRef\n  subst: {:?}\n", trait_ref.substs);
 147
 148     path
 149 }
 150
 151 impl<'tcx> Clean<'tcx, Path> for ty::TraitRef<'tcx> {
 152     fn clean(&self, cx: &mut DocContext<'tcx>) -> Path {
 153         clean_trait_ref_with_bindings(cx, *self, &[])
 154     }
 155 }
 156
 157 fn clean_poly_trait_ref_with_bindings<'tcx>(
 158     cx: &mut DocContext<'tcx>,
 159     poly_trait_ref: ty::PolyTraitRef<'tcx>,
 160     bindings: &[TypeBinding],
 161 ) -> GenericBound {
 162     let poly_trait_ref = poly_trait_ref.lift_to_tcx(cx.tcx).unwrap();
 163
 164     // collect any late bound regions
 165     let late_bound_regions: Vec<_> = cx
 166         .tcx
 167         .collect_referenced_late_bound_regions(&poly_trait_ref)
 168         .into_iter()
 169         .filter_map(|br| match br {
 170             ty::BrNamed(_, name) => Some(GenericParamDef {
 171                 name,
 172                 kind: GenericParamDefKind::Lifetime { outlives: vec![] },
 173             }),
 174             _ => None,
 175         })
 176         .collect();
 177
 178     let trait_ = clean_trait_ref_with_bindings(cx, poly_trait_ref.skip_binder(), bindings);
 179     GenericBound::TraitBound(
 180         PolyTrait { trait_, generic_params: late_bound_regions },
 181         hir::TraitBoundModifier::None,
 182     )
 183 }
 184
 185 impl<'tcx> Clean<'tcx, GenericBound> for ty::PolyTraitRef<'tcx> {
 186     fn clean(&self, cx: &mut DocContext<'tcx>) -> GenericBound {
 187         clean_poly_trait_ref_with_bindings(cx, *self, &[])
 188     }
 189 }
 190
 191 impl<'tcx> Clean<'tcx, Lifetime> for hir::Lifetime {
 192     fn clean(&self, cx: &mut DocContext<'tcx>) -> Lifetime {
 193         let def = cx.tcx.named_region(self.hir_id);
 194         if let Some(
 195             rl::Region::EarlyBound(_, node_id)
 196             | rl::Region::LateBound(_, _, node_id)
 197             | rl::Region::Free(_, node_id),
 198         ) = def
 199         {
 200             if let Some(lt) = cx.substs.get(&node_id).and_then(|p| p.as_lt()).cloned() {
 201                 return lt;
 202             }
 203         }
 204         Lifetime(self.name.ident().name)
 205     }
 206 }
 207
 208 impl<'tcx> Clean<'tcx, Constant> for hir::ConstArg {
 209     fn clean(&self, cx: &mut DocContext<'tcx>) -> Constant {
 210         Constant {
 211             type_: cx
 212                 .tcx
 213                 .type_of(cx.tcx.hir().body_owner_def_id(self.value.body).to_def_id())
 214                 .clean(cx),
 215             kind: ConstantKind::Anonymous { body: self.value.body },
 216         }
 217     }
 218 }
 219
 220 impl<'tcx> Clean<'tcx, Option<Lifetime>> for ty::Region<'tcx> {
 221     fn clean(&self, _cx: &mut DocContext<'_>) -> Option<Lifetime> {
 222         match **self {
 223             ty::ReStatic => Some(Lifetime::statik()),
 224             ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => {
 225                 if name != kw::UnderscoreLifetime { Some(Lifetime(name)) } else { None }
 226             }
 227             ty::ReEarlyBound(ref data) => {
 228                 if data.name != kw::UnderscoreLifetime {
 229                     Some(Lifetime(data.name))
 230                 } else {
 231                     None
 232                 }
 233             }
 234             ty::ReLateBound(..)
 235             | ty::ReFree(..)
 236             | ty::ReVar(..)
 237             | ty::RePlaceholder(..)
 238             | ty::ReEmpty(_)
 239             | ty::ReErased => {
 240                 debug!("cannot clean region {:?}", self);
 241                 None
 242             }
 243         }
 244     }
 245 }
 246
 247 impl<'tcx> Clean<'tcx, Option<WherePredicate>> for hir::WherePredicate<'tcx> {
 248     fn clean(&self, cx: &mut DocContext<'tcx>) -> Option<WherePredicate> {
 249         if !self.in_where_clause() {
 250             return None;
 251         }
 252         Some(match *self {
 253             hir::WherePredicate::BoundPredicate(ref wbp) => {
 254                 let bound_params = wbp
 255                     .bound_generic_params
 256                     .iter()
 257                     .map(|param| {
 258                         // Higher-ranked params must be lifetimes.
 259                         // Higher-ranked lifetimes can't have bounds.
 260                         assert_matches!(
 261                             param,
 262                             hir::GenericParam { kind: hir::GenericParamKind::Lifetime { .. }, .. }
 263                         );
 264                         Lifetime(param.name.ident().name)
 265                     })
 266                     .collect();
 267                 WherePredicate::BoundPredicate {
 268                     ty: wbp.bounded_ty.clean(cx),
 269                     bounds: wbp.bounds.iter().filter_map(|x| x.clean(cx)).collect(),
 270                     bound_params,
 271                 }
 272             }
 273
 274             hir::WherePredicate::RegionPredicate(ref wrp) => WherePredicate::RegionPredicate {
 275                 lifetime: wrp.lifetime.clean(cx),
 276                 bounds: wrp.bounds.iter().filter_map(|x| x.clean(cx)).collect(),
 277             },
 278
 279             hir::WherePredicate::EqPredicate(ref wrp) => WherePredicate::EqPredicate {
 280                 lhs: wrp.lhs_ty.clean(cx),
 281                 rhs: wrp.rhs_ty.clean(cx).into(),
 282             },
 283         })
 284     }
 285 }
 286
 287 impl<'tcx> Clean<'tcx, Option<WherePredicate>> for ty::Predicate<'tcx> {
 288     fn clean(&self, cx: &mut DocContext<'tcx>) -> Option<WherePredicate> {
 289         let bound_predicate = self.kind();
 290         match bound_predicate.skip_binder() {
 291             ty::PredicateKind::Trait(pred) => bound_predicate.rebind(pred).clean(cx),
 292             ty::PredicateKind::RegionOutlives(pred) => pred.clean(cx),
 293             ty::PredicateKind::TypeOutlives(pred) => pred.clean(cx),
 294             ty::PredicateKind::Projection(pred) => Some(pred.clean(cx)),
 295             ty::PredicateKind::ConstEvaluatable(..) => None,
 296             ty::PredicateKind::WellFormed(..) => None,
 297
 298             ty::PredicateKind::Subtype(..)
 299             | ty::PredicateKind::Coerce(..)
 300             | ty::PredicateKind::ObjectSafe(..)
 301             | ty::PredicateKind::ClosureKind(..)
 302             | ty::PredicateKind::ConstEquate(..)
 303             | ty::PredicateKind::TypeWellFormedFromEnv(..) => panic!("not user writable"),
 304         }
 305     }
 306 }
 307
 308 impl<'tcx> Clean<'tcx, Option<WherePredicate>> for ty::PolyTraitPredicate<'tcx> {
 309     fn clean(&self, cx: &mut DocContext<'tcx>) -> Option<WherePredicate> {
 310         // `T: ~const Destruct` is hidden because `T: Destruct` is a no-op.
 311         if self.skip_binder().constness == ty::BoundConstness::ConstIfConst
 312             && Some(self.skip_binder().def_id()) == cx.tcx.lang_items().destruct_trait()
 313         {
 314             return None;
 315         }
 316
 317         let poly_trait_ref = self.map_bound(|pred| pred.trait_ref);
 318         Some(WherePredicate::BoundPredicate {
 319             ty: poly_trait_ref.skip_binder().self_ty().clean(cx),
 320             bounds: vec![poly_trait_ref.clean(cx)],
 321             bound_params: Vec::new(),
 322         })
 323     }
 324 }
 325
 326 impl<'tcx> Clean<'tcx, Option<WherePredicate>>
 327     for ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
 328 {
 329     fn clean(&self, cx: &mut DocContext<'tcx>) -> Option<WherePredicate> {
 330         let ty::OutlivesPredicate(a, b) = self;
 331
 332         if a.is_empty() && b.is_empty() {
 333             return None;
 334         }
 335
 336         Some(WherePredicate::RegionPredicate {
 337             lifetime: a.clean(cx).expect("failed to clean lifetime"),
 338             bounds: vec![GenericBound::Outlives(b.clean(cx).expect("failed to clean bounds"))],
 339         })
 340     }
 341 }
 342
 343 impl<'tcx> Clean<'tcx, Option<WherePredicate>>
 344     for ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>
 345 {
 346     fn clean(&self, cx: &mut DocContext<'tcx>) -> Option<WherePredicate> {
 347         let ty::OutlivesPredicate(ty, lt) = self;
 348
 349         if lt.is_empty() {
 350             return None;
 351         }
 352
 353         Some(WherePredicate::BoundPredicate {
 354             ty: ty.clean(cx),
 355             bounds: vec![GenericBound::Outlives(lt.clean(cx).expect("failed to clean lifetimes"))],
 356             bound_params: Vec::new(),
 357         })
 358     }
 359 }
 360
 361 impl<'tcx> Clean<'tcx, Term> for ty::Term<'tcx> {
 362     fn clean(&self, cx: &mut DocContext<'tcx>) -> Term {
 363         match self {
 364             ty::Term::Ty(ty) => Term::Type(ty.clean(cx)),
 365             ty::Term::Const(c) => Term::Constant(c.clean(cx)),
 366         }
 367     }
 368 }
 369
 370 impl<'tcx> Clean<'tcx, Term> for hir::Term<'tcx> {
 371     fn clean(&self, cx: &mut DocContext<'tcx>) -> Term {
 372         match self {
 373             hir::Term::Ty(ty) => Term::Type(ty.clean(cx)),
 374             hir::Term::Const(c) => {
 375                 let def_id = cx.tcx.hir().local_def_id(c.hir_id);
 376                 Term::Constant(ty::Const::from_anon_const(cx.tcx, def_id).clean(cx))
 377             }
 378         }
 379     }
 380 }
 381
 382 impl<'tcx> Clean<'tcx, WherePredicate> for ty::ProjectionPredicate<'tcx> {
 383     fn clean(&self, cx: &mut DocContext<'tcx>) -> WherePredicate {
 384         let ty::ProjectionPredicate { projection_ty, term } = self;
 385         WherePredicate::EqPredicate { lhs: projection_ty.clean(cx), rhs: term.clean(cx) }
 386     }
 387 }
 388
 389 fn clean_projection<'tcx>(
 390     ty: ty::ProjectionTy<'tcx>,
 391     cx: &mut DocContext<'tcx>,
 392     def_id: Option<DefId>,
 393 ) -> Type {
 394     let lifted = ty.lift_to_tcx(cx.tcx).unwrap();
 395     let trait_ = lifted.trait_ref(cx.tcx).clean(cx);
 396     let self_type = ty.self_ty().clean(cx);
 397     let self_def_id = if let Some(def_id) = def_id {
 398         cx.tcx.opt_parent(def_id).or(Some(def_id))
 399     } else {
 400         self_type.def_id(&cx.cache)
 401     };
 402     let should_show_cast = compute_should_show_cast(self_def_id, &trait_, &self_type);
 403     Type::QPath {
 404         assoc: Box::new(projection_to_path_segment(ty, cx)),
 405         should_show_cast,
 406         self_type: box self_type,
 407         trait_,
 408     }
 409 }
 410
 411 impl<'tcx> Clean<'tcx, Type> for ty::ProjectionTy<'tcx> {
 412     fn clean(&self, cx: &mut DocContext<'tcx>) -> Type {
 413         clean_projection(*self, cx, None)
 414     }
 415 }
 416
 417 fn compute_should_show_cast(self_def_id: Option<DefId>, trait_: &Path, self_type: &Type) -> bool {
 418     !trait_.segments.is_empty()
 419         && self_def_id
 420             .zip(Some(trait_.def_id()))
 421             .map_or(!self_type.is_self_type(), |(id, trait_)| id != trait_)
 422 }
 423
 424 fn projection_to_path_segment<'tcx>(
 425     ty: ty::ProjectionTy<'tcx>,
 426     cx: &mut DocContext<'tcx>,
 427 ) -> PathSegment {
 428     let item = cx.tcx.associated_item(ty.item_def_id);
 429     let generics = cx.tcx.generics_of(ty.item_def_id);
 430     PathSegment {
 431         name: item.name,
 432         args: GenericArgs::AngleBracketed {
 433             args: substs_to_args(cx, &ty.substs[generics.parent_count..], false).into(),
 434             bindings: Default::default(),
 435         },
 436     }
 437 }
 438
 439 impl<'tcx> Clean<'tcx, GenericParamDef> for ty::GenericParamDef {
 440     fn clean(&self, cx: &mut DocContext<'tcx>) -> GenericParamDef {
 441         let (name, kind) = match self.kind {
 442             ty::GenericParamDefKind::Lifetime => {
 443                 (self.name, GenericParamDefKind::Lifetime { outlives: vec![] })
 444             }
 445             ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
 446                 let default = if has_default {
 447                     Some(clean_ty(cx.tcx.type_of(self.def_id), cx, Some(self.def_id)))
 448                 } else {
 449                     None
 450                 };
 451                 (
 452                     self.name,
 453                     GenericParamDefKind::Type {
 454                         did: self.def_id,
 455                         bounds: vec![], // These are filled in from the where-clauses.
 456                         default: default.map(Box::new),
 457                         synthetic,
 458                     },
 459                 )
 460             }
 461             ty::GenericParamDefKind::Const { has_default } => (
 462                 self.name,
 463                 GenericParamDefKind::Const {
 464                     did: self.def_id,
 465                     ty: Box::new(cx.tcx.type_of(self.def_id).clean(cx)),
 466                     default: match has_default {
 467                         true => Some(Box::new(cx.tcx.const_param_default(self.def_id).to_string())),
 468                         false => None,
 469                     },
 470                 },
 471             ),
 472         };
 473
 474         GenericParamDef { name, kind }
 475     }
 476 }
 477
 478 fn clean_generic_param<'tcx>(
 479     cx: &mut DocContext<'tcx>,
 480     generics: Option<&hir::Generics<'tcx>>,
 481     param: &hir::GenericParam<'tcx>,
 482 ) -> GenericParamDef {
 483     let did = cx.tcx.hir().local_def_id(param.hir_id);
 484     let (name, kind) = match param.kind {
 485         hir::GenericParamKind::Lifetime { .. } => {
 486             let outlives = if let Some(generics) = generics {
 487                 generics
 488                     .outlives_for_param(did)
 489                     .filter(|bp| !bp.in_where_clause)
 490                     .flat_map(|bp| bp.bounds)
 491                     .map(|bound| match bound {
 492                         hir::GenericBound::Outlives(lt) => lt.clean(cx),
 493                         _ => panic!(),
 494                     })
 495                     .collect()
 496             } else {
 497                 Vec::new()
 498             };
 499             (param.name.ident().name, GenericParamDefKind::Lifetime { outlives })
 500         }
 501         hir::GenericParamKind::Type { ref default, synthetic } => {
 502             let bounds = if let Some(generics) = generics {
 503                 generics
 504                     .bounds_for_param(did)
 505                     .filter(|bp| bp.origin != PredicateOrigin::WhereClause)
 506                     .flat_map(|bp| bp.bounds)
 507                     .filter_map(|x| x.clean(cx))
 508                     .collect()
 509             } else {
 510                 Vec::new()
 511             };
 512             (
 513                 param.name.ident().name,
 514                 GenericParamDefKind::Type {
 515                     did: did.to_def_id(),
 516                     bounds,
 517                     default: default.map(|t| t.clean(cx)).map(Box::new),
 518                     synthetic,
 519                 },
 520             )
 521         }
 522         hir::GenericParamKind::Const { ty, default } => (
 523             param.name.ident().name,
 524             GenericParamDefKind::Const {
 525                 did: did.to_def_id(),
 526                 ty: Box::new(ty.clean(cx)),
 527                 default: default.map(|ct| {
 528                     let def_id = cx.tcx.hir().local_def_id(ct.hir_id);
 529                     Box::new(ty::Const::from_anon_const(cx.tcx, def_id).to_string())
 530                 }),
 531             },
 532         ),
 533     };
 534
 535     GenericParamDef { name, kind }
 536 }
 537
 538 /// Synthetic type-parameters are inserted after normal ones.
 539 /// In order for normal parameters to be able to refer to synthetic ones,
 540 /// scans them first.
 541 fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
 542     match param.kind {
 543         hir::GenericParamKind::Type { synthetic, .. } => synthetic,
 544         _ => false,
 545     }
 546 }
 547
 548 /// This can happen for `async fn`, e.g. `async fn f<'_>(&'_ self)`.
 549 ///
 550 /// See `lifetime_to_generic_param` in `rustc_ast_lowering` for more information.
 551 fn is_elided_lifetime(param: &hir::GenericParam<'_>) -> bool {
 552     matches!(param.kind, hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided })
 553 }
 554
 555 impl<'tcx> Clean<'tcx, Generics> for hir::Generics<'tcx> {
 556     fn clean(&self, cx: &mut DocContext<'tcx>) -> Generics {
 557         let impl_trait_params = self
 558             .params
 559             .iter()
 560             .filter(|param| is_impl_trait(param))
 561             .map(|param| {
 562                 let param = clean_generic_param(cx, Some(self), param);
 563                 match param.kind {
 564                     GenericParamDefKind::Lifetime { .. } => unreachable!(),
 565                     GenericParamDefKind::Type { did, ref bounds, .. } => {
 566                         cx.impl_trait_bounds.insert(did.into(), bounds.clone());
 567                     }
 568                     GenericParamDefKind::Const { .. } => unreachable!(),
 569                 }
 570                 param
 571             })
 572             .collect::<Vec<_>>();
 573
 574         let mut params = Vec::with_capacity(self.params.len());
 575         for p in self.params.iter().filter(|p| !is_impl_trait(p) && !is_elided_lifetime(p)) {
 576             let p = clean_generic_param(cx, Some(self), p);
 577             params.push(p);
 578         }
 579         params.extend(impl_trait_params);
 580
 581         let mut generics = Generics {
 582             params,
 583             where_predicates: self.predicates.iter().filter_map(|x| x.clean(cx)).collect(),
 584         };
 585
 586         // Some duplicates are generated for ?Sized bounds between type params and where
 587         // predicates. The point in here is to move the bounds definitions from type params
 588         // to where predicates when such cases occur.
 589         for where_pred in &mut generics.where_predicates {
 590             match *where_pred {
 591                 WherePredicate::BoundPredicate {
 592                     ty: Generic(ref name), ref mut bounds, ..
 593                 } => {
 594                     if bounds.is_empty() {
 595                         for param in &mut generics.params {
 596                             match param.kind {
 597                                 GenericParamDefKind::Lifetime { .. } => {}
 598                                 GenericParamDefKind::Type { bounds: ref mut ty_bounds, .. } => {
 599                                     if &param.name == name {
 600                                         mem::swap(bounds, ty_bounds);
 601                                         break;
 602                                     }
 603                                 }
 604                                 GenericParamDefKind::Const { .. } => {}
 605                             }
 606                         }
 607                     }
 608                 }
 609                 _ => continue,
 610             }
 611         }
 612         generics
 613     }
 614 }
 615
 616 fn clean_ty_generics<'tcx>(
 617     cx: &mut DocContext<'tcx>,
 618     gens: &ty::Generics,
 619     preds: ty::GenericPredicates<'tcx>,
 620 ) -> Generics {
 621     // Don't populate `cx.impl_trait_bounds` before `clean`ning `where` clauses,
 622     // since `Clean for ty::Predicate` would consume them.
 623     let mut impl_trait = BTreeMap::<ImplTraitParam, Vec<GenericBound>>::default();
 624
 625     // Bounds in the type_params and lifetimes fields are repeated in the
 626     // predicates field (see rustc_typeck::collect::ty_generics), so remove
 627     // them.
 628     let stripped_params = gens
 629         .params
 630         .iter()
 631         .filter_map(|param| match param.kind {
 632             ty::GenericParamDefKind::Lifetime => Some(param.clean(cx)),
 633             ty::GenericParamDefKind::Type { synthetic, .. } => {
 634                 if param.name == kw::SelfUpper {
 635                     assert_eq!(param.index, 0);
 636                     return None;
 637                 }
 638                 if synthetic {
 639                     impl_trait.insert(param.index.into(), vec![]);
 640                     return None;
 641                 }
 642                 Some(param.clean(cx))
 643             }
 644             ty::GenericParamDefKind::Const { .. } => Some(param.clean(cx)),
 645         })
 646         .collect::<Vec<GenericParamDef>>();
 647
 648     // param index -> [(DefId of trait, associated type name and generics, type)]
 649     let mut impl_trait_proj = FxHashMap::<u32, Vec<(DefId, PathSegment, Ty<'_>)>>::default();
 650
 651     let where_predicates = preds
 652         .predicates
 653         .iter()
 654         .flat_map(|(p, _)| {
 655             let mut projection = None;
 656             let param_idx = (|| {
 657                 let bound_p = p.kind();
 658                 match bound_p.skip_binder() {
 659                     ty::PredicateKind::Trait(pred) => {
 660                         if let ty::Param(param) = pred.self_ty().kind() {
 661                             return Some(param.index);
 662                         }
 663                     }
 664                     ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty, _reg)) => {
 665                         if let ty::Param(param) = ty.kind() {
 666                             return Some(param.index);
 667                         }
 668                     }
 669                     ty::PredicateKind::Projection(p) => {
 670                         if let ty::Param(param) = p.projection_ty.self_ty().kind() {
 671                             projection = Some(bound_p.rebind(p));
 672                             return Some(param.index);
 673                         }
 674                     }
 675                     _ => (),
 676                 }
 677
 678                 None
 679             })();
 680
 681             if let Some(param_idx) = param_idx {
 682                 if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
 683                     let p: WherePredicate = p.clean(cx)?;
 684
 685                     b.extend(
 686                         p.get_bounds()
 687                             .into_iter()
 688                             .flatten()
 689                             .cloned()
 690                             .filter(|b| !b.is_sized_bound(cx)),
 691                     );
 692
 693                     let proj = projection
 694                         .map(|p| (p.skip_binder().projection_ty.clean(cx), p.skip_binder().term));
 695                     if let Some(((_, trait_did, name), rhs)) = proj
 696                         .as_ref()
 697                         .and_then(|(lhs, rhs): &(Type, _)| Some((lhs.projection()?, rhs)))
 698                     {
 699                         // FIXME(...): Remove this unwrap()
 700                         impl_trait_proj.entry(param_idx).or_default().push((
 701                             trait_did,
 702                             name,
 703                             rhs.ty().unwrap(),
 704                         ));
 705                     }
 706
 707                     return None;
 708                 }
 709             }
 710
 711             Some(p)
 712         })
 713         .collect::<Vec<_>>();
 714
 715     for (param, mut bounds) in impl_trait {
 716         // Move trait bounds to the front.
 717         bounds.sort_by_key(|b| !matches!(b, GenericBound::TraitBound(..)));
 718
 719         if let crate::core::ImplTraitParam::ParamIndex(idx) = param {
 720             if let Some(proj) = impl_trait_proj.remove(&idx) {
 721                 for (trait_did, name, rhs) in proj {
 722                     let rhs = rhs.clean(cx);
 723                     simplify::merge_bounds(cx, &mut bounds, trait_did, name, &Term::Type(rhs));
 724                 }
 725             }
 726         } else {
 727             unreachable!();
 728         }
 729
 730         cx.impl_trait_bounds.insert(param, bounds);
 731     }
 732
 733     // Now that `cx.impl_trait_bounds` is populated, we can process
 734     // remaining predicates which could contain `impl Trait`.
 735     let mut where_predicates =
 736         where_predicates.into_iter().flat_map(|p| p.clean(cx)).collect::<Vec<_>>();
 737
 738     // Type parameters have a Sized bound by default unless removed with
 739     // ?Sized. Scan through the predicates and mark any type parameter with
 740     // a Sized bound, removing the bounds as we find them.
 741     //
 742     // Note that associated types also have a sized bound by default, but we
 743     // don't actually know the set of associated types right here so that's
 744     // handled in cleaning associated types
 745     let mut sized_params = FxHashSet::default();
 746     where_predicates.retain(|pred| match *pred {
 747         WherePredicate::BoundPredicate { ty: Generic(ref g), ref bounds, .. } => {
 748             if bounds.iter().any(|b| b.is_sized_bound(cx)) {
 749                 sized_params.insert(*g);
 750                 false
 751             } else {
 752                 true
 753             }
 754         }
 755         _ => true,
 756     });
 757
 758     // Run through the type parameters again and insert a ?Sized
 759     // unbound for any we didn't find to be Sized.
 760     for tp in &stripped_params {
 761         if matches!(tp.kind, types::GenericParamDefKind::Type { .. })
 762             && !sized_params.contains(&tp.name)
 763         {
 764             where_predicates.push(WherePredicate::BoundPredicate {
 765                 ty: Type::Generic(tp.name),
 766                 bounds: vec![GenericBound::maybe_sized(cx)],
 767                 bound_params: Vec::new(),
 768             })
 769         }
 770     }
 771
 772     // It would be nice to collect all of the bounds on a type and recombine
 773     // them if possible, to avoid e.g., `where T: Foo, T: Bar, T: Sized, T: 'a`
 774     // and instead see `where T: Foo + Bar + Sized + 'a`
 775
 776     Generics {
 777         params: stripped_params,
 778         where_predicates: simplify::where_clauses(cx, where_predicates),
 779     }
 780 }
 781
 782 fn clean_fn_or_proc_macro<'tcx>(
 783     item: &hir::Item<'tcx>,
 784     sig: &hir::FnSig<'tcx>,
 785     generics: &hir::Generics<'tcx>,
 786     body_id: hir::BodyId,
 787     name: &mut Symbol,
 788     cx: &mut DocContext<'tcx>,
 789 ) -> ItemKind {
 790     let attrs = cx.tcx.hir().attrs(item.hir_id());
 791     let macro_kind = attrs.iter().find_map(|a| {
 792         if a.has_name(sym::proc_macro) {
 793             Some(MacroKind::Bang)
 794         } else if a.has_name(sym::proc_macro_derive) {
 795             Some(MacroKind::Derive)
 796         } else if a.has_name(sym::proc_macro_attribute) {
 797             Some(MacroKind::Attr)
 798         } else {
 799             None
 800         }
 801     });
 802     match macro_kind {
 803         Some(kind) => {
 804             if kind == MacroKind::Derive {
 805                 *name = attrs
 806                     .lists(sym::proc_macro_derive)
 807                     .find_map(|mi| mi.ident())
 808                     .expect("proc-macro derives require a name")
 809                     .name;
 810             }
 811
 812             let mut helpers = Vec::new();
 813             for mi in attrs.lists(sym::proc_macro_derive) {
 814                 if !mi.has_name(sym::attributes) {
 815                     continue;
 816                 }
 817
 818                 if let Some(list) = mi.meta_item_list() {
 819                     for inner_mi in list {
 820                         if let Some(ident) = inner_mi.ident() {
 821                             helpers.push(ident.name);
 822                         }
 823                     }
 824                 }
 825             }
 826             ProcMacroItem(ProcMacro { kind, helpers })
 827         }
 828         None => {
 829             let mut func = clean_function(cx, sig, generics, body_id);
 830             clean_fn_decl_legacy_const_generics(&mut func, attrs);
 831             FunctionItem(func)
 832         }
 833     }
 834 }
 835
 836 /// This is needed to make it more "readable" when documenting functions using
 837 /// `rustc_legacy_const_generics`. More information in
 838 /// <https://github.com/rust-lang/rust/issues/83167>.
 839 fn clean_fn_decl_legacy_const_generics(func: &mut Function, attrs: &[ast::Attribute]) {
 840     for meta_item_list in attrs
 841         .iter()
 842         .filter(|a| a.has_name(sym::rustc_legacy_const_generics))
 843         .filter_map(|a| a.meta_item_list())
 844     {
 845         for (pos, literal) in meta_item_list.iter().filter_map(|meta| meta.literal()).enumerate() {
 846             match literal.kind {
 847                 ast::LitKind::Int(a, _) => {
 848                     let gen = func.generics.params.remove(0);
 849                     if let GenericParamDef { name, kind: GenericParamDefKind::Const { ty, .. } } =
 850                         gen
 851                     {
 852                         func.decl
 853                             .inputs
 854                             .values
 855                             .insert(a as _, Argument { name, type_: *ty, is_const: true });
 856                     } else {
 857                         panic!("unexpected non const in position {pos}");
 858                     }
 859                 }
 860                 _ => panic!("invalid arg index"),
 861             }
 862         }
 863     }
 864 }
 865
 866 fn clean_function<'tcx>(
 867     cx: &mut DocContext<'tcx>,
 868     sig: &hir::FnSig<'tcx>,
 869     generics: &hir::Generics<'tcx>,
 870     body_id: hir::BodyId,
 871 ) -> Function {
 872     let (generics, decl) = enter_impl_trait(cx, |cx| {
 873         // NOTE: generics must be cleaned before args
 874         let generics = generics.clean(cx);
 875         let args = clean_args_from_types_and_body_id(cx, sig.decl.inputs, body_id);
 876         let decl = clean_fn_decl_with_args(cx, sig.decl, args);
 877         (generics, decl)
 878     });
 879     Function { decl, generics }
 880 }
 881
 882 fn clean_args_from_types_and_names<'tcx>(
 883     cx: &mut DocContext<'tcx>,
 884     types: &[hir::Ty<'tcx>],
 885     names: &[Ident],
 886 ) -> Arguments {
 887     Arguments {
 888         values: types
 889             .iter()
 890             .enumerate()
 891             .map(|(i, ty)| {
 892                 let mut name = names.get(i).map_or(kw::Empty, |ident| ident.name);
 893                 if name.is_empty() {
 894                     name = kw::Underscore;
 895                 }
 896                 Argument { name, type_: ty.clean(cx), is_const: false }
 897             })
 898             .collect(),
 899     }
 900 }
 901
 902 fn clean_args_from_types_and_body_id<'tcx>(
 903     cx: &mut DocContext<'tcx>,
 904     types: &[hir::Ty<'tcx>],
 905     body_id: hir::BodyId,
 906 ) -> Arguments {
 907     let body = cx.tcx.hir().body(body_id);
 908
 909     Arguments {
 910         values: types
 911             .iter()
 912             .enumerate()
 913             .map(|(i, ty)| Argument {
 914                 name: name_from_pat(body.params[i].pat),
 915                 type_: ty.clean(cx),
 916                 is_const: false,
 917             })
 918             .collect(),
 919     }
 920 }
 921
 922 fn clean_fn_decl_with_args<'tcx>(
 923     cx: &mut DocContext<'tcx>,
 924     decl: &hir::FnDecl<'tcx>,
 925     args: Arguments,
 926 ) -> FnDecl {
 927     FnDecl { inputs: args, output: decl.output.clean(cx), c_variadic: decl.c_variadic }
 928 }
 929
 930 fn clean_fn_decl_from_did_and_sig<'tcx>(
 931     cx: &mut DocContext<'tcx>,
 932     did: Option<DefId>,
 933     sig: ty::PolyFnSig<'tcx>,
 934 ) -> FnDecl {
 935     let mut names = did.map_or(&[] as &[_], |did| cx.tcx.fn_arg_names(did)).iter();
 936
 937     // We assume all empty tuples are default return type. This theoretically can discard `-> ()`,
 938     // but shouldn't change any code meaning.
 939     let output = match sig.skip_binder().output().clean(cx) {
 940         Type::Tuple(inner) if inner.is_empty() => DefaultReturn,
 941         ty => Return(ty),
 942     };
 943
 944     FnDecl {
 945         output,
 946         c_variadic: sig.skip_binder().c_variadic,
 947         inputs: Arguments {
 948             values: sig
 949                 .skip_binder()
 950                 .inputs()
 951                 .iter()
 952                 .map(|t| Argument {
 953                     type_: t.clean(cx),
 954                     name: names.next().map_or(kw::Empty, |i| i.name),
 955                     is_const: false,
 956                 })
 957                 .collect(),
 958         },
 959     }
 960 }
 961
 962 impl<'tcx> Clean<'tcx, FnRetTy> for hir::FnRetTy<'tcx> {
 963     fn clean(&self, cx: &mut DocContext<'tcx>) -> FnRetTy {
 964         match *self {
 965             Self::Return(typ) => Return(typ.clean(cx)),
 966             Self::DefaultReturn(..) => DefaultReturn,
 967         }
 968     }
 969 }
 970
 971 impl<'tcx> Clean<'tcx, bool> for hir::IsAuto {
 972     fn clean(&self, _: &mut DocContext<'tcx>) -> bool {
 973         match *self {
 974             hir::IsAuto::Yes => true,
 975             hir::IsAuto::No => false,
 976         }
 977     }
 978 }
 979
 980 impl<'tcx> Clean<'tcx, Path> for hir::TraitRef<'tcx> {
 981     fn clean(&self, cx: &mut DocContext<'tcx>) -> Path {
 982         let path = self.path.clean(cx);
 983         register_res(cx, path.res);
 984         path
 985     }
 986 }
 987
 988 impl<'tcx> Clean<'tcx, PolyTrait> for hir::PolyTraitRef<'tcx> {
 989     fn clean(&self, cx: &mut DocContext<'tcx>) -> PolyTrait {
 990         PolyTrait {
 991             trait_: self.trait_ref.clean(cx),
 992             generic_params: self
 993                 .bound_generic_params
 994                 .iter()
 995                 .filter(|p| !is_elided_lifetime(p))
 996                 .map(|x| clean_generic_param(cx, None, x))
 997                 .collect(),
 998         }
 999     }
1000 }
1001
1002 impl<'tcx> Clean<'tcx, Item> for hir::TraitItem<'tcx> {
1003     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
1004         let local_did = self.def_id.to_def_id();
1005         cx.with_param_env(local_did, |cx| {
1006             let inner = match self.kind {
1007                 hir::TraitItemKind::Const(ty, Some(default)) => AssocConstItem(
1008                     ty.clean(cx),
1009                     ConstantKind::Local { def_id: local_did, body: default },
1010                 ),
1011                 hir::TraitItemKind::Const(ty, None) => TyAssocConstItem(ty.clean(cx)),
1012                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
1013                     let m = clean_function(cx, sig, self.generics, body);
1014                     MethodItem(m, None)
1015                 }
1016                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(names)) => {
1017                     let (generics, decl) = enter_impl_trait(cx, |cx| {
1018                         // NOTE: generics must be cleaned before args
1019                         let generics = self.generics.clean(cx);
1020                         let args = clean_args_from_types_and_names(cx, sig.decl.inputs, names);
1021                         let decl = clean_fn_decl_with_args(cx, sig.decl, args);
1022                         (generics, decl)
1023                     });
1024                     TyMethodItem(Function { decl, generics })
1025                 }
1026                 hir::TraitItemKind::Type(bounds, Some(default)) => {
1027                     let generics = enter_impl_trait(cx, |cx| self.generics.clean(cx));
1028                     let bounds = bounds.iter().filter_map(|x| x.clean(cx)).collect();
1029                     let item_type = hir_ty_to_ty(cx.tcx, default).clean(cx);
1030                     AssocTypeItem(
1031                         Typedef { type_: default.clean(cx), generics, item_type: Some(item_type) },
1032                         bounds,
1033                     )
1034                 }
1035                 hir::TraitItemKind::Type(bounds, None) => {
1036                     let generics = enter_impl_trait(cx, |cx| self.generics.clean(cx));
1037                     let bounds = bounds.iter().filter_map(|x| x.clean(cx)).collect();
1038                     TyAssocTypeItem(Box::new(generics), bounds)
1039                 }
1040             };
1041             let what_rustc_thinks =
1042                 Item::from_def_id_and_parts(local_did, Some(self.ident.name), inner, cx);
1043             // Trait items always inherit the trait's visibility -- we don't want to show `pub`.
1044             Item { visibility: Inherited, ..what_rustc_thinks }
1045         })
1046     }
1047 }
1048
1049 impl<'tcx> Clean<'tcx, Item> for hir::ImplItem<'tcx> {
1050     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
1051         let local_did = self.def_id.to_def_id();
1052         cx.with_param_env(local_did, |cx| {
1053             let inner = match self.kind {
1054                 hir::ImplItemKind::Const(ty, expr) => {
1055                     let default = ConstantKind::Local { def_id: local_did, body: expr };
1056                     AssocConstItem(ty.clean(cx), default)
1057                 }
1058                 hir::ImplItemKind::Fn(ref sig, body) => {
1059                     let m = clean_function(cx, sig, self.generics, body);
1060                     let defaultness = cx.tcx.associated_item(self.def_id).defaultness;
1061                     MethodItem(m, Some(defaultness))
1062                 }
1063                 hir::ImplItemKind::TyAlias(hir_ty) => {
1064                     let type_ = hir_ty.clean(cx);
1065                     let generics = self.generics.clean(cx);
1066                     let item_type = hir_ty_to_ty(cx.tcx, hir_ty).clean(cx);
1067                     AssocTypeItem(
1068                         Typedef { type_, generics, item_type: Some(item_type) },
1069                         Vec::new(),
1070                     )
1071                 }
1072             };
1073
1074             let mut what_rustc_thinks =
1075                 Item::from_def_id_and_parts(local_did, Some(self.ident.name), inner, cx);
1076
1077             let impl_ref = cx.tcx.impl_trait_ref(cx.tcx.local_parent(self.def_id));
1078
1079             // Trait impl items always inherit the impl's visibility --
1080             // we don't want to show `pub`.
1081             if impl_ref.is_some() {
1082                 what_rustc_thinks.visibility = Inherited;
1083             }
1084
1085             what_rustc_thinks
1086         })
1087     }
1088 }
1089
1090 impl<'tcx> Clean<'tcx, Item> for ty::AssocItem {
1091     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
1092         let tcx = cx.tcx;
1093         let kind = match self.kind {
1094             ty::AssocKind::Const => {
1095                 let ty = tcx.type_of(self.def_id).clean(cx);
1096
1097                 let provided = match self.container {
1098                     ty::ImplContainer(_) => true,
1099                     ty::TraitContainer(_) => self.defaultness.has_value(),
1100                 };
1101                 if provided {
1102                     AssocConstItem(ty, ConstantKind::Extern { def_id: self.def_id })
1103                 } else {
1104                     TyAssocConstItem(ty)
1105                 }
1106             }
1107             ty::AssocKind::Fn => {
1108                 let generics = clean_ty_generics(
1109                     cx,
1110                     tcx.generics_of(self.def_id),
1111                     tcx.explicit_predicates_of(self.def_id),
1112                 );
1113                 let sig = tcx.fn_sig(self.def_id);
1114                 let mut decl = clean_fn_decl_from_did_and_sig(cx, Some(self.def_id), sig);
1115
1116                 if self.fn_has_self_parameter {
1117                     let self_ty = match self.container {
1118                         ty::ImplContainer(def_id) => tcx.type_of(def_id),
1119                         ty::TraitContainer(_) => tcx.types.self_param,
1120                     };
1121                     let self_arg_ty = sig.input(0).skip_binder();
1122                     if self_arg_ty == self_ty {
1123                         decl.inputs.values[0].type_ = Generic(kw::SelfUpper);
1124                     } else if let ty::Ref(_, ty, _) = *self_arg_ty.kind() {
1125                         if ty == self_ty {
1126                             match decl.inputs.values[0].type_ {
1127                                 BorrowedRef { ref mut type_, .. } => {
1128                                     **type_ = Generic(kw::SelfUpper)
1129                                 }
1130                                 _ => unreachable!(),
1131                             }
1132                         }
1133                     }
1134                 }
1135
1136                 let provided = match self.container {
1137                     ty::ImplContainer(_) => true,
1138                     ty::TraitContainer(_) => self.defaultness.has_value(),
1139                 };
1140                 if provided {
1141                     let defaultness = match self.container {
1142                         ty::ImplContainer(_) => Some(self.defaultness),
1143                         ty::TraitContainer(_) => None,
1144                     };
1145                     MethodItem(Function { generics, decl }, defaultness)
1146                 } else {
1147                     TyMethodItem(Function { generics, decl })
1148                 }
1149             }
1150             ty::AssocKind::Type => {
1151                 let my_name = self.name;
1152
1153                 fn param_eq_arg(param: &GenericParamDef, arg: &GenericArg) -> bool {
1154                     match (&param.kind, arg) {
1155                         (GenericParamDefKind::Type { .. }, GenericArg::Type(Type::Generic(ty)))
1156                             if *ty == param.name =>
1157                         {
1158                             true
1159                         }
1160                         (
1161                             GenericParamDefKind::Lifetime { .. },
1162                             GenericArg::Lifetime(Lifetime(lt)),
1163                         ) if *lt == param.name => true,
1164                         (GenericParamDefKind::Const { .. }, GenericArg::Const(c)) => {
1165                             match &c.kind {
1166                                 ConstantKind::TyConst { expr } => expr == param.name.as_str(),
1167                                 _ => false,
1168                             }
1169                         }
1170                         _ => false,
1171                     }
1172                 }
1173
1174                 if let ty::TraitContainer(_) = self.container {
1175                     let bounds = tcx.explicit_item_bounds(self.def_id);
1176                     let predicates = ty::GenericPredicates { parent: None, predicates: bounds };
1177                     let mut generics =
1178                         clean_ty_generics(cx, tcx.generics_of(self.def_id), predicates);
1179                     // Filter out the bounds that are (likely?) directly attached to the associated type,
1180                     // as opposed to being located in the where clause.
1181                     let mut bounds = generics
1182                         .where_predicates
1183                         .drain_filter(|pred| match *pred {
1184                             WherePredicate::BoundPredicate {
1185                                 ty: QPath { ref assoc, ref self_type, ref trait_, .. },
1186                                 ..
1187                             } => {
1188                                 if assoc.name != my_name {
1189                                     return false;
1190                                 }
1191                                 if trait_.def_id() != self.container.id() {
1192                                     return false;
1193                                 }
1194                                 match **self_type {
1195                                     Generic(ref s) if *s == kw::SelfUpper => {}
1196                                     _ => return false,
1197                                 }
1198                                 match &assoc.args {
1199                                     GenericArgs::AngleBracketed { args, bindings } => {
1200                                         if !bindings.is_empty()
1201                                             || generics
1202                                                 .params
1203                                                 .iter()
1204                                                 .zip(args.iter())
1205                                                 .any(|(param, arg)| !param_eq_arg(param, arg))
1206                                         {
1207                                             return false;
1208                                         }
1209                                     }
1210                                     GenericArgs::Parenthesized { .. } => {
1211                                         // The only time this happens is if we're inside the rustdoc for Fn(),
1212                                         // which only has one associated type, which is not a GAT, so whatever.
1213                                     }
1214                                 }
1215                                 true
1216                             }
1217                             _ => false,
1218                         })
1219                         .flat_map(|pred| {
1220                             if let WherePredicate::BoundPredicate { bounds, .. } = pred {
1221                                 bounds
1222                             } else {
1223                                 unreachable!()
1224                             }
1225                         })
1226                         .collect::<Vec<_>>();
1227                     // Our Sized/?Sized bound didn't get handled when creating the generics
1228                     // because we didn't actually get our whole set of bounds until just now
1229                     // (some of them may have come from the trait). If we do have a sized
1230                     // bound, we remove it, and if we don't then we add the `?Sized` bound
1231                     // at the end.
1232                     match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1233                         Some(i) => {
1234                             bounds.remove(i);
1235                         }
1236                         None => bounds.push(GenericBound::maybe_sized(cx)),
1237                     }
1238
1239                     if self.defaultness.has_value() {
1240                         AssocTypeItem(
1241                             Typedef {
1242                                 type_: tcx.type_of(self.def_id).clean(cx),
1243                                 generics,
1244                                 // FIXME: should we obtain the Type from HIR and pass it on here?
1245                                 item_type: None,
1246                             },
1247                             bounds,
1248                         )
1249                     } else {
1250                         TyAssocTypeItem(Box::new(generics), bounds)
1251                     }
1252                 } else {
1253                     // FIXME: when could this happen? Associated items in inherent impls?
1254                     AssocTypeItem(
1255                         Typedef {
1256                             type_: tcx.type_of(self.def_id).clean(cx),
1257                             generics: Generics { params: Vec::new(), where_predicates: Vec::new() },
1258                             item_type: None,
1259                         },
1260                         Vec::new(),
1261                     )
1262                 }
1263             }
1264         };
1265
1266         let mut what_rustc_thinks =
1267             Item::from_def_id_and_parts(self.def_id, Some(self.name), kind, cx);
1268
1269         let impl_ref = tcx.impl_trait_ref(tcx.parent(self.def_id));
1270
1271         // Trait impl items always inherit the impl's visibility --
1272         // we don't want to show `pub`.
1273         if impl_ref.is_some() {
1274             what_rustc_thinks.visibility = Visibility::Inherited;
1275         }
1276
1277         what_rustc_thinks
1278     }
1279 }
1280
1281 fn clean_qpath<'tcx>(hir_ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1282     let hir::Ty { hir_id: _, span, ref kind } = *hir_ty;
1283     let hir::TyKind::Path(qpath) = kind else { unreachable!() };
1284
1285     match qpath {
1286         hir::QPath::Resolved(None, path) => {
1287             if let Res::Def(DefKind::TyParam, did) = path.res {
1288                 if let Some(new_ty) = cx.substs.get(&did).and_then(|p| p.as_ty()).cloned() {
1289                     return new_ty;
1290                 }
1291                 if let Some(bounds) = cx.impl_trait_bounds.remove(&did.into()) {
1292                     return ImplTrait(bounds);
1293                 }
1294             }
1295
1296             if let Some(expanded) = maybe_expand_private_type_alias(cx, path) {
1297                 expanded
1298             } else {
1299                 let path = path.clean(cx);
1300                 resolve_type(cx, path)
1301             }
1302         }
1303         hir::QPath::Resolved(Some(qself), p) => {
1304             // Try to normalize `<X as Y>::T` to a type
1305             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1306             if let Some(normalized_value) = normalize(cx, ty) {
1307                 return normalized_value.clean(cx);
1308             }
1309
1310             let trait_segments = &p.segments[..p.segments.len() - 1];
1311             let trait_def = cx.tcx.associated_item(p.res.def_id()).container.id();
1312             let trait_ = self::Path {
1313                 res: Res::Def(DefKind::Trait, trait_def),
1314                 segments: trait_segments.iter().map(|x| x.clean(cx)).collect(),
1315             };
1316             register_res(cx, trait_.res);
1317             let self_def_id = DefId::local(qself.hir_id.owner.local_def_index);
1318             let self_type = qself.clean(cx);
1319             let should_show_cast = compute_should_show_cast(Some(self_def_id), &trait_, &self_type);
1320             Type::QPath {
1321                 assoc: Box::new(p.segments.last().expect("segments were empty").clean(cx)),
1322                 should_show_cast,
1323                 self_type: box self_type,
1324                 trait_,
1325             }
1326         }
1327         hir::QPath::TypeRelative(qself, segment) => {
1328             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1329             let res = match ty.kind() {
1330                 ty::Projection(proj) => Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id),
1331                 // Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
1332                 ty::Error(_) => return Type::Infer,
1333                 _ => bug!("clean: expected associated type, found `{:?}`", ty),
1334             };
1335             let trait_ = hir::Path { span, res, segments: &[] }.clean(cx);
1336             register_res(cx, trait_.res);
1337             let self_def_id = res.opt_def_id();
1338             let self_type = qself.clean(cx);
1339             let should_show_cast = compute_should_show_cast(self_def_id, &trait_, &self_type);
1340             Type::QPath {
1341                 assoc: Box::new(segment.clean(cx)),
1342                 should_show_cast,
1343                 self_type: box self_type,
1344                 trait_,
1345             }
1346         }
1347         hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1348     }
1349 }
1350
1351 fn maybe_expand_private_type_alias<'tcx>(
1352     cx: &mut DocContext<'tcx>,
1353     path: &hir::Path<'tcx>,
1354 ) -> Option<Type> {
1355     let Res::Def(DefKind::TyAlias, def_id) = path.res else { return None };
1356     // Substitute private type aliases
1357     let def_id = def_id.as_local()?;
1358     let alias = if !cx.cache.access_levels.is_exported(def_id.to_def_id()) {
1359         &cx.tcx.hir().expect_item(def_id).kind
1360     } else {
1361         return None;
1362     };
1363     let hir::ItemKind::TyAlias(ty, generics) = alias else { return None };
1364
1365     let provided_params = &path.segments.last().expect("segments were empty");
1366     let mut substs = FxHashMap::default();
1367     let generic_args = provided_params.args();
1368
1369     let mut indices: hir::GenericParamCount = Default::default();
1370     for param in generics.params.iter() {
1371         match param.kind {
1372             hir::GenericParamKind::Lifetime { .. } => {
1373                 let mut j = 0;
1374                 let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1375                     hir::GenericArg::Lifetime(lt) => {
1376                         if indices.lifetimes == j {
1377                             return Some(lt);
1378                         }
1379                         j += 1;
1380                         None
1381                     }
1382                     _ => None,
1383                 });
1384                 if let Some(lt) = lifetime.cloned() {
1385                     let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1386                     let cleaned = if !lt.is_elided() { lt.clean(cx) } else { Lifetime::elided() };
1387                     substs.insert(lt_def_id.to_def_id(), SubstParam::Lifetime(cleaned));
1388                 }
1389                 indices.lifetimes += 1;
1390             }
1391             hir::GenericParamKind::Type { ref default, .. } => {
1392                 let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1393                 let mut j = 0;
1394                 let type_ = generic_args.args.iter().find_map(|arg| match arg {
1395                     hir::GenericArg::Type(ty) => {
1396                         if indices.types == j {
1397                             return Some(ty);
1398                         }
1399                         j += 1;
1400                         None
1401                     }
1402                     _ => None,
1403                 });
1404                 if let Some(ty) = type_ {
1405                     substs.insert(ty_param_def_id.to_def_id(), SubstParam::Type(ty.clean(cx)));
1406                 } else if let Some(default) = *default {
1407                     substs.insert(ty_param_def_id.to_def_id(), SubstParam::Type(default.clean(cx)));
1408                 }
1409                 indices.types += 1;
1410             }
1411             hir::GenericParamKind::Const { .. } => {
1412                 let const_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1413                 let mut j = 0;
1414                 let const_ = generic_args.args.iter().find_map(|arg| match arg {
1415                     hir::GenericArg::Const(ct) => {
1416                         if indices.consts == j {
1417                             return Some(ct);
1418                         }
1419                         j += 1;
1420                         None
1421                     }
1422                     _ => None,
1423                 });
1424                 if let Some(ct) = const_ {
1425                     substs
1426                         .insert(const_param_def_id.to_def_id(), SubstParam::Constant(ct.clean(cx)));
1427                 }
1428                 // FIXME(const_generics_defaults)
1429                 indices.consts += 1;
1430             }
1431         }
1432     }
1433
1434     Some(cx.enter_alias(substs, |cx| ty.clean(cx)))
1435 }
1436
1437 impl<'tcx> Clean<'tcx, Type> for hir::Ty<'tcx> {
1438     fn clean(&self, cx: &mut DocContext<'tcx>) -> Type {
1439         use rustc_hir::*;
1440
1441         match self.kind {
1442             TyKind::Never => Primitive(PrimitiveType::Never),
1443             TyKind::Ptr(ref m) => RawPointer(m.mutbl, box m.ty.clean(cx)),
1444             TyKind::Rptr(ref l, ref m) => {
1445                 // There are two times a `Fresh` lifetime can be created:
1446                 // 1. For `&'_ x`, written by the user. This corresponds to `lower_lifetime` in `rustc_ast_lowering`.
1447                 // 2. For `&x` as a parameter to an `async fn`. This corresponds to `elided_ref_lifetime in `rustc_ast_lowering`.
1448                 //    See #59286 for more information.
1449                 // Ideally we would only hide the `'_` for case 2., but I don't know a way to distinguish it.
1450                 // Turning `fn f(&'_ self)` into `fn f(&self)` isn't the worst thing in the world, though;
1451                 // there's no case where it could cause the function to fail to compile.
1452                 let elided =
1453                     l.is_elided() || matches!(l.name, LifetimeName::Param(_, ParamName::Fresh));
1454                 let lifetime = if elided { None } else { Some(l.clean(cx)) };
1455                 BorrowedRef { lifetime, mutability: m.mutbl, type_: box m.ty.clean(cx) }
1456             }
1457             TyKind::Slice(ty) => Slice(box ty.clean(cx)),
1458             TyKind::Array(ty, ref length) => {
1459                 let length = match length {
1460                     hir::ArrayLen::Infer(_, _) => "_".to_string(),
1461                     hir::ArrayLen::Body(anon_const) => {
1462                         let def_id = cx.tcx.hir().local_def_id(anon_const.hir_id);
1463                         // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1464                         // as we currently do not supply the parent generics to anonymous constants
1465                         // but do allow `ConstKind::Param`.
1466                         //
1467                         // `const_eval_poly` tries to to first substitute generic parameters which
1468                         // results in an ICE while manually constructing the constant and using `eval`
1469                         // does nothing for `ConstKind::Param`.
1470                         let ct = ty::Const::from_anon_const(cx.tcx, def_id);
1471                         let param_env = cx.tcx.param_env(def_id);
1472                         print_const(cx, ct.eval(cx.tcx, param_env))
1473                     }
1474                 };
1475
1476                 Array(box ty.clean(cx), length)
1477             }
1478             TyKind::Tup(tys) => Tuple(tys.iter().map(|x| x.clean(cx)).collect()),
1479             TyKind::OpaqueDef(item_id, _) => {
1480                 let item = cx.tcx.hir().item(item_id);
1481                 if let hir::ItemKind::OpaqueTy(ref ty) = item.kind {
1482                     ImplTrait(ty.bounds.iter().filter_map(|x| x.clean(cx)).collect())
1483                 } else {
1484                     unreachable!()
1485                 }
1486             }
1487             TyKind::Path(_) => clean_qpath(self, cx),
1488             TyKind::TraitObject(bounds, ref lifetime, _) => {
1489                 let bounds = bounds.iter().map(|bound| bound.clean(cx)).collect();
1490                 let lifetime = if !lifetime.is_elided() { Some(lifetime.clean(cx)) } else { None };
1491                 DynTrait(bounds, lifetime)
1492             }
1493             TyKind::BareFn(barefn) => BareFunction(box barefn.clean(cx)),
1494             // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
1495             TyKind::Infer | TyKind::Err => Infer,
1496             TyKind::Typeof(..) => panic!("unimplemented type {:?}", self.kind),
1497         }
1498     }
1499 }
1500
1501 /// Returns `None` if the type could not be normalized
1502 fn normalize<'tcx>(cx: &mut DocContext<'tcx>, ty: Ty<'_>) -> Option<Ty<'tcx>> {
1503     // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1504     if !cx.tcx.sess.opts.debugging_opts.normalize_docs {
1505         return None;
1506     }
1507
1508     use crate::rustc_trait_selection::infer::TyCtxtInferExt;
1509     use crate::rustc_trait_selection::traits::query::normalize::AtExt;
1510     use rustc_middle::traits::ObligationCause;
1511
1512     // Try to normalize `<X as Y>::T` to a type
1513     let lifted = ty.lift_to_tcx(cx.tcx).unwrap();
1514     let normalized = cx.tcx.infer_ctxt().enter(|infcx| {
1515         infcx
1516             .at(&ObligationCause::dummy(), cx.param_env)
1517             .normalize(lifted)
1518             .map(|resolved| infcx.resolve_vars_if_possible(resolved.value))
1519     });
1520     match normalized {
1521         Ok(normalized_value) => {
1522             debug!("normalized {:?} to {:?}", ty, normalized_value);
1523             Some(normalized_value)
1524         }
1525         Err(err) => {
1526             debug!("failed to normalize {:?}: {:?}", ty, err);
1527             None
1528         }
1529     }
1530 }
1531
1532 fn clean_ty<'tcx>(this: Ty<'tcx>, cx: &mut DocContext<'tcx>, def_id: Option<DefId>) -> Type {
1533     trace!("cleaning type: {:?}", this);
1534     let ty = normalize(cx, this).unwrap_or(this);
1535     match *ty.kind() {
1536         ty::Never => Primitive(PrimitiveType::Never),
1537         ty::Bool => Primitive(PrimitiveType::Bool),
1538         ty::Char => Primitive(PrimitiveType::Char),
1539         ty::Int(int_ty) => Primitive(int_ty.into()),
1540         ty::Uint(uint_ty) => Primitive(uint_ty.into()),
1541         ty::Float(float_ty) => Primitive(float_ty.into()),
1542         ty::Str => Primitive(PrimitiveType::Str),
1543         ty::Slice(ty) => Slice(box ty.clean(cx)),
1544         ty::Array(ty, n) => {
1545             let mut n = cx.tcx.lift(n).expect("array lift failed");
1546             n = n.eval(cx.tcx, ty::ParamEnv::reveal_all());
1547             let n = print_const(cx, n);
1548             Array(box ty.clean(cx), n)
1549         }
1550         ty::RawPtr(mt) => RawPointer(mt.mutbl, box mt.ty.clean(cx)),
1551         ty::Ref(r, ty, mutbl) => {
1552             BorrowedRef { lifetime: r.clean(cx), mutability: mutbl, type_: box ty.clean(cx) }
1553         }
1554         ty::FnDef(..) | ty::FnPtr(_) => {
1555             let ty = cx.tcx.lift(this).expect("FnPtr lift failed");
1556             let sig = ty.fn_sig(cx.tcx);
1557             let decl = clean_fn_decl_from_did_and_sig(cx, None, sig);
1558             BareFunction(box BareFunctionDecl {
1559                 unsafety: sig.unsafety(),
1560                 generic_params: Vec::new(),
1561                 decl,
1562                 abi: sig.abi(),
1563             })
1564         }
1565         ty::Adt(def, substs) => {
1566             let did = def.did();
1567             let kind = match def.adt_kind() {
1568                 AdtKind::Struct => ItemType::Struct,
1569                 AdtKind::Union => ItemType::Union,
1570                 AdtKind::Enum => ItemType::Enum,
1571             };
1572             inline::record_extern_fqn(cx, did, kind);
1573             let path = external_path(cx, did, false, vec![], substs);
1574             Type::Path { path }
1575         }
1576         ty::Foreign(did) => {
1577             inline::record_extern_fqn(cx, did, ItemType::ForeignType);
1578             let path = external_path(cx, did, false, vec![], InternalSubsts::empty());
1579             Type::Path { path }
1580         }
1581         ty::Dynamic(obj, ref reg) => {
1582             // HACK: pick the first `did` as the `did` of the trait object. Someone
1583             // might want to implement "native" support for marker-trait-only
1584             // trait objects.
1585             let mut dids = obj.principal_def_id().into_iter().chain(obj.auto_traits());
1586             let did = dids
1587                 .next()
1588                 .unwrap_or_else(|| panic!("found trait object `{:?}` with no traits?", this));
1589             let substs = match obj.principal() {
1590                 Some(principal) => principal.skip_binder().substs,
1591                 // marker traits have no substs.
1592                 _ => cx.tcx.intern_substs(&[]),
1593             };
1594
1595             inline::record_extern_fqn(cx, did, ItemType::Trait);
1596
1597             let lifetime = reg.clean(cx);
1598             let mut bounds = vec![];
1599
1600             for did in dids {
1601                 let empty = cx.tcx.intern_substs(&[]);
1602                 let path = external_path(cx, did, false, vec![], empty);
1603                 inline::record_extern_fqn(cx, did, ItemType::Trait);
1604                 let bound = PolyTrait { trait_: path, generic_params: Vec::new() };
1605                 bounds.push(bound);
1606             }
1607
1608             let mut bindings = vec![];
1609             for pb in obj.projection_bounds() {
1610                 bindings.push(TypeBinding {
1611                     assoc: projection_to_path_segment(
1612                         pb.skip_binder()
1613                             .lift_to_tcx(cx.tcx)
1614                             .unwrap()
1615                             // HACK(compiler-errors): Doesn't actually matter what self
1616                             // type we put here, because we're only using the GAT's substs.
1617                             .with_self_ty(cx.tcx, cx.tcx.types.self_param)
1618                             .projection_ty,
1619                         cx,
1620                     ),
1621                     kind: TypeBindingKind::Equality { term: pb.skip_binder().term.clean(cx) },
1622                 });
1623             }
1624
1625             let path = external_path(cx, did, false, bindings, substs);
1626             bounds.insert(0, PolyTrait { trait_: path, generic_params: Vec::new() });
1627
1628             DynTrait(bounds, lifetime)
1629         }
1630         ty::Tuple(t) => Tuple(t.iter().map(|t| t.clean(cx)).collect()),
1631
1632         ty::Projection(ref data) => clean_projection(*data, cx, def_id),
1633
1634         ty::Param(ref p) => {
1635             if let Some(bounds) = cx.impl_trait_bounds.remove(&p.index.into()) {
1636                 ImplTrait(bounds)
1637             } else {
1638                 Generic(p.name)
1639             }
1640         }
1641
1642         ty::Opaque(def_id, substs) => {
1643             // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1644             // by looking up the bounds associated with the def_id.
1645             let substs = cx.tcx.lift(substs).expect("Opaque lift failed");
1646             let bounds = cx
1647                 .tcx
1648                 .explicit_item_bounds(def_id)
1649                 .iter()
1650                 .map(|(bound, _)| EarlyBinder(*bound).subst(cx.tcx, substs))
1651                 .collect::<Vec<_>>();
1652             let mut regions = vec![];
1653             let mut has_sized = false;
1654             let mut bounds = bounds
1655                 .iter()
1656                 .filter_map(|bound| {
1657                     let bound_predicate = bound.kind();
1658                     let trait_ref = match bound_predicate.skip_binder() {
1659                         ty::PredicateKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
1660                         ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
1661                             if let Some(r) = reg.clean(cx) {
1662                                 regions.push(GenericBound::Outlives(r));
1663                             }
1664                             return None;
1665                         }
1666                         _ => return None,
1667                     };
1668
1669                     if let Some(sized) = cx.tcx.lang_items().sized_trait() {
1670                         if trait_ref.def_id() == sized {
1671                             has_sized = true;
1672                             return None;
1673                         }
1674                     }
1675
1676                     let bindings: Vec<_> = bounds
1677                         .iter()
1678                         .filter_map(|bound| {
1679                             if let ty::PredicateKind::Projection(proj) = bound.kind().skip_binder()
1680                             {
1681                                 if proj.projection_ty.trait_ref(cx.tcx) == trait_ref.skip_binder() {
1682                                     Some(TypeBinding {
1683                                         assoc: projection_to_path_segment(proj.projection_ty, cx),
1684                                         kind: TypeBindingKind::Equality {
1685                                             term: proj.term.clean(cx),
1686                                         },
1687                                     })
1688                                 } else {
1689                                     None
1690                                 }
1691                             } else {
1692                                 None
1693                             }
1694                         })
1695                         .collect();
1696
1697                     Some(clean_poly_trait_ref_with_bindings(cx, trait_ref, &bindings))
1698                 })
1699                 .collect::<Vec<_>>();
1700             bounds.extend(regions);
1701             if !has_sized && !bounds.is_empty() {
1702                 bounds.insert(0, GenericBound::maybe_sized(cx));
1703             }
1704             ImplTrait(bounds)
1705         }
1706
1707         ty::Closure(..) | ty::Generator(..) => Tuple(vec![]), // FIXME(pcwalton)
1708
1709         ty::Bound(..) => panic!("Bound"),
1710         ty::Placeholder(..) => panic!("Placeholder"),
1711         ty::GeneratorWitness(..) => panic!("GeneratorWitness"),
1712         ty::Infer(..) => panic!("Infer"),
1713         ty::Error(_) => panic!("Error"),
1714     }
1715 }
1716
1717 impl<'tcx> Clean<'tcx, Type> for Ty<'tcx> {
1718     fn clean(&self, cx: &mut DocContext<'tcx>) -> Type {
1719         clean_ty(*self, cx, None)
1720     }
1721 }
1722
1723 impl<'tcx> Clean<'tcx, Constant> for ty::Const<'tcx> {
1724     fn clean(&self, cx: &mut DocContext<'tcx>) -> Constant {
1725         // FIXME: instead of storing the stringified expression, store `self` directly instead.
1726         Constant {
1727             type_: self.ty().clean(cx),
1728             kind: ConstantKind::TyConst { expr: self.to_string() },
1729         }
1730     }
1731 }
1732
1733 impl<'tcx> Clean<'tcx, Item> for hir::FieldDef<'tcx> {
1734     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
1735         let def_id = cx.tcx.hir().local_def_id(self.hir_id).to_def_id();
1736         clean_field(def_id, self.ident.name, self.ty.clean(cx), cx)
1737     }
1738 }
1739
1740 impl<'tcx> Clean<'tcx, Item> for ty::FieldDef {
1741     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
1742         clean_field(self.did, self.name, cx.tcx.type_of(self.did).clean(cx), cx)
1743     }
1744 }
1745
1746 fn clean_field(def_id: DefId, name: Symbol, ty: Type, cx: &mut DocContext<'_>) -> Item {
1747     let what_rustc_thinks =
1748         Item::from_def_id_and_parts(def_id, Some(name), StructFieldItem(ty), cx);
1749     if is_field_vis_inherited(cx.tcx, def_id) {
1750         // Variant fields inherit their enum's visibility.
1751         Item { visibility: Visibility::Inherited, ..what_rustc_thinks }
1752     } else {
1753         what_rustc_thinks
1754     }
1755 }
1756
1757 fn is_field_vis_inherited(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
1758     let parent = tcx.parent(def_id);
1759     match tcx.def_kind(parent) {
1760         DefKind::Struct | DefKind::Union => false,
1761         DefKind::Variant => true,
1762         // FIXME: what about DefKind::Ctor?
1763         parent_kind => panic!("unexpected parent kind: {:?}", parent_kind),
1764     }
1765 }
1766
1767 impl<'tcx> Clean<'tcx, Visibility> for ty::Visibility {
1768     fn clean(&self, _cx: &mut DocContext<'_>) -> Visibility {
1769         match *self {
1770             ty::Visibility::Public => Visibility::Public,
1771             // NOTE: this is not quite right: `ty` uses `Invisible` to mean 'private',
1772             // while rustdoc really does mean inherited. That means that for enum variants, such as
1773             // `pub enum E { V }`, `V` will be marked as `Public` by `ty`, but as `Inherited` by rustdoc.
1774             // Various parts of clean override `tcx.visibility` explicitly to make sure this distinction is captured.
1775             ty::Visibility::Invisible => Visibility::Inherited,
1776             ty::Visibility::Restricted(module) => Visibility::Restricted(module),
1777         }
1778     }
1779 }
1780
1781 impl<'tcx> Clean<'tcx, VariantStruct> for rustc_hir::VariantData<'tcx> {
1782     fn clean(&self, cx: &mut DocContext<'tcx>) -> VariantStruct {
1783         VariantStruct {
1784             struct_type: CtorKind::from_hir(self),
1785             fields: self.fields().iter().map(|x| x.clean(cx)).collect(),
1786         }
1787     }
1788 }
1789
1790 impl<'tcx> Clean<'tcx, Vec<Item>> for hir::VariantData<'tcx> {
1791     fn clean(&self, cx: &mut DocContext<'tcx>) -> Vec<Item> {
1792         self.fields().iter().map(|x| x.clean(cx)).collect()
1793     }
1794 }
1795
1796 impl<'tcx> Clean<'tcx, Item> for ty::VariantDef {
1797     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
1798         let kind = match self.ctor_kind {
1799             CtorKind::Const => Variant::CLike,
1800             CtorKind::Fn => {
1801                 Variant::Tuple(self.fields.iter().map(|field| field.clean(cx)).collect())
1802             }
1803             CtorKind::Fictive => Variant::Struct(VariantStruct {
1804                 struct_type: CtorKind::Fictive,
1805                 fields: self.fields.iter().map(|field| field.clean(cx)).collect(),
1806             }),
1807         };
1808         let what_rustc_thinks =
1809             Item::from_def_id_and_parts(self.def_id, Some(self.name), VariantItem(kind), cx);
1810         // don't show `pub` for variants, which always inherit visibility
1811         Item { visibility: Inherited, ..what_rustc_thinks }
1812     }
1813 }
1814
1815 impl<'tcx> Clean<'tcx, Variant> for hir::VariantData<'tcx> {
1816     fn clean(&self, cx: &mut DocContext<'tcx>) -> Variant {
1817         match self {
1818             hir::VariantData::Struct(..) => Variant::Struct(self.clean(cx)),
1819             hir::VariantData::Tuple(..) => Variant::Tuple(self.clean(cx)),
1820             hir::VariantData::Unit(..) => Variant::CLike,
1821         }
1822     }
1823 }
1824
1825 impl<'tcx> Clean<'tcx, Path> for hir::Path<'tcx> {
1826     fn clean(&self, cx: &mut DocContext<'tcx>) -> Path {
1827         Path { res: self.res, segments: self.segments.iter().map(|x| x.clean(cx)).collect() }
1828     }
1829 }
1830
1831 impl<'tcx> Clean<'tcx, GenericArgs> for hir::GenericArgs<'tcx> {
1832     fn clean(&self, cx: &mut DocContext<'tcx>) -> GenericArgs {
1833         if self.parenthesized {
1834             let output = self.bindings[0].ty().clean(cx);
1835             let output =
1836                 if output != Type::Tuple(Vec::new()) { Some(Box::new(output)) } else { None };
1837             let inputs = self.inputs().iter().map(|x| x.clean(cx)).collect::<Vec<_>>().into();
1838             GenericArgs::Parenthesized { inputs, output }
1839         } else {
1840             let args = self
1841                 .args
1842                 .iter()
1843                 .map(|arg| match arg {
1844                     hir::GenericArg::Lifetime(lt) if !lt.is_elided() => {
1845                         GenericArg::Lifetime(lt.clean(cx))
1846                     }
1847                     hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
1848                     hir::GenericArg::Type(ty) => GenericArg::Type(ty.clean(cx)),
1849                     hir::GenericArg::Const(ct) => GenericArg::Const(Box::new(ct.clean(cx))),
1850                     hir::GenericArg::Infer(_inf) => GenericArg::Infer,
1851                 })
1852                 .collect::<Vec<_>>()
1853                 .into();
1854             let bindings = self.bindings.iter().map(|x| x.clean(cx)).collect::<Vec<_>>().into();
1855             GenericArgs::AngleBracketed { args, bindings }
1856         }
1857     }
1858 }
1859
1860 impl<'tcx> Clean<'tcx, PathSegment> for hir::PathSegment<'tcx> {
1861     fn clean(&self, cx: &mut DocContext<'tcx>) -> PathSegment {
1862         PathSegment { name: self.ident.name, args: self.args().clean(cx) }
1863     }
1864 }
1865
1866 impl<'tcx> Clean<'tcx, BareFunctionDecl> for hir::BareFnTy<'tcx> {
1867     fn clean(&self, cx: &mut DocContext<'tcx>) -> BareFunctionDecl {
1868         let (generic_params, decl) = enter_impl_trait(cx, |cx| {
1869             // NOTE: generics must be cleaned before args
1870             let generic_params = self
1871                 .generic_params
1872                 .iter()
1873                 .filter(|p| !is_elided_lifetime(p))
1874                 .map(|x| clean_generic_param(cx, None, x))
1875                 .collect();
1876             let args = clean_args_from_types_and_names(cx, self.decl.inputs, self.param_names);
1877             let decl = clean_fn_decl_with_args(cx, self.decl, args);
1878             (generic_params, decl)
1879         });
1880         BareFunctionDecl { unsafety: self.unsafety, abi: self.abi, decl, generic_params }
1881     }
1882 }
1883
1884 fn clean_maybe_renamed_item<'tcx>(
1885     cx: &mut DocContext<'tcx>,
1886     item: &hir::Item<'tcx>,
1887     renamed: Option<Symbol>,
1888 ) -> Vec<Item> {
1889     use hir::ItemKind;
1890
1891     let def_id = item.def_id.to_def_id();
1892     let mut name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
1893     cx.with_param_env(def_id, |cx| {
1894         let kind = match item.kind {
1895             ItemKind::Static(ty, mutability, body_id) => {
1896                 StaticItem(Static { type_: ty.clean(cx), mutability, expr: Some(body_id) })
1897             }
1898             ItemKind::Const(ty, body_id) => ConstantItem(Constant {
1899                 type_: ty.clean(cx),
1900                 kind: ConstantKind::Local { body: body_id, def_id },
1901             }),
1902             ItemKind::OpaqueTy(ref ty) => OpaqueTyItem(OpaqueTy {
1903                 bounds: ty.bounds.iter().filter_map(|x| x.clean(cx)).collect(),
1904                 generics: ty.generics.clean(cx),
1905             }),
1906             ItemKind::TyAlias(hir_ty, generics) => {
1907                 let rustdoc_ty = hir_ty.clean(cx);
1908                 let ty = hir_ty_to_ty(cx.tcx, hir_ty).clean(cx);
1909                 TypedefItem(Typedef {
1910                     type_: rustdoc_ty,
1911                     generics: generics.clean(cx),
1912                     item_type: Some(ty),
1913                 })
1914             }
1915             ItemKind::Enum(ref def, generics) => EnumItem(Enum {
1916                 variants: def.variants.iter().map(|v| v.clean(cx)).collect(),
1917                 generics: generics.clean(cx),
1918             }),
1919             ItemKind::TraitAlias(generics, bounds) => TraitAliasItem(TraitAlias {
1920                 generics: generics.clean(cx),
1921                 bounds: bounds.iter().filter_map(|x| x.clean(cx)).collect(),
1922             }),
1923             ItemKind::Union(ref variant_data, generics) => UnionItem(Union {
1924                 generics: generics.clean(cx),
1925                 fields: variant_data.fields().iter().map(|x| x.clean(cx)).collect(),
1926             }),
1927             ItemKind::Struct(ref variant_data, generics) => StructItem(Struct {
1928                 struct_type: CtorKind::from_hir(variant_data),
1929                 generics: generics.clean(cx),
1930                 fields: variant_data.fields().iter().map(|x| x.clean(cx)).collect(),
1931             }),
1932             ItemKind::Impl(impl_) => return clean_impl(impl_, item.hir_id(), cx),
1933             // proc macros can have a name set by attributes
1934             ItemKind::Fn(ref sig, generics, body_id) => {
1935                 clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
1936             }
1937             ItemKind::Macro(ref macro_def, _) => {
1938                 let ty_vis = cx.tcx.visibility(def_id).clean(cx);
1939                 MacroItem(Macro {
1940                     source: display_macro_source(cx, name, macro_def, def_id, ty_vis),
1941                 })
1942             }
1943             ItemKind::Trait(is_auto, unsafety, generics, bounds, item_ids) => {
1944                 let items =
1945                     item_ids.iter().map(|ti| cx.tcx.hir().trait_item(ti.id).clean(cx)).collect();
1946                 TraitItem(Trait {
1947                     unsafety,
1948                     items,
1949                     generics: generics.clean(cx),
1950                     bounds: bounds.iter().filter_map(|x| x.clean(cx)).collect(),
1951                     is_auto: is_auto.clean(cx),
1952                 })
1953             }
1954             ItemKind::ExternCrate(orig_name) => {
1955                 return clean_extern_crate(item, name, orig_name, cx);
1956             }
1957             ItemKind::Use(path, kind) => {
1958                 return clean_use_statement(item, name, path, kind, cx);
1959             }
1960             _ => unreachable!("not yet converted"),
1961         };
1962
1963         vec![Item::from_def_id_and_parts(def_id, Some(name), kind, cx)]
1964     })
1965 }
1966
1967 impl<'tcx> Clean<'tcx, Item> for hir::Variant<'tcx> {
1968     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
1969         let kind = VariantItem(self.data.clean(cx));
1970         let what_rustc_thinks =
1971             Item::from_hir_id_and_parts(self.id, Some(self.ident.name), kind, cx);
1972         // don't show `pub` for variants, which are always public
1973         Item { visibility: Inherited, ..what_rustc_thinks }
1974     }
1975 }
1976
1977 fn clean_impl<'tcx>(
1978     impl_: &hir::Impl<'tcx>,
1979     hir_id: hir::HirId,
1980     cx: &mut DocContext<'tcx>,
1981 ) -> Vec<Item> {
1982     let tcx = cx.tcx;
1983     let mut ret = Vec::new();
1984     let trait_ = impl_.of_trait.as_ref().map(|t| t.clean(cx));
1985     let items =
1986         impl_.items.iter().map(|ii| tcx.hir().impl_item(ii.id).clean(cx)).collect::<Vec<_>>();
1987     let def_id = tcx.hir().local_def_id(hir_id);
1988
1989     // If this impl block is an implementation of the Deref trait, then we
1990     // need to try inlining the target's inherent impl blocks as well.
1991     if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
1992         build_deref_target_impls(cx, &items, &mut ret);
1993     }
1994
1995     let for_ = impl_.self_ty.clean(cx);
1996     let type_alias = for_.def_id(&cx.cache).and_then(|did| match tcx.def_kind(did) {
1997         DefKind::TyAlias => Some(tcx.type_of(did).clean(cx)),
1998         _ => None,
1999     });
2000     let mut make_item = |trait_: Option<Path>, for_: Type, items: Vec<Item>| {
2001         let kind = ImplItem(Impl {
2002             unsafety: impl_.unsafety,
2003             generics: impl_.generics.clean(cx),
2004             trait_,
2005             for_,
2006             items,
2007             polarity: tcx.impl_polarity(def_id),
2008             kind: if utils::has_doc_flag(tcx, def_id.to_def_id(), sym::tuple_variadic) {
2009                 ImplKind::TupleVaradic
2010             } else {
2011                 ImplKind::Normal
2012             },
2013         });
2014         Item::from_hir_id_and_parts(hir_id, None, kind, cx)
2015     };
2016     if let Some(type_alias) = type_alias {
2017         ret.push(make_item(trait_.clone(), type_alias, items.clone()));
2018     }
2019     ret.push(make_item(trait_, for_, items));
2020     ret
2021 }
2022
2023 fn clean_extern_crate<'tcx>(
2024     krate: &hir::Item<'tcx>,
2025     name: Symbol,
2026     orig_name: Option<Symbol>,
2027     cx: &mut DocContext<'tcx>,
2028 ) -> Vec<Item> {
2029     // this is the ID of the `extern crate` statement
2030     let cnum = cx.tcx.extern_mod_stmt_cnum(krate.def_id).unwrap_or(LOCAL_CRATE);
2031     // this is the ID of the crate itself
2032     let crate_def_id = cnum.as_def_id();
2033     let attrs = cx.tcx.hir().attrs(krate.hir_id());
2034     let ty_vis = cx.tcx.visibility(krate.def_id);
2035     let please_inline = ty_vis.is_public()
2036         && attrs.iter().any(|a| {
2037             a.has_name(sym::doc)
2038                 && match a.meta_item_list() {
2039                     Some(l) => attr::list_contains_name(&l, sym::inline),
2040                     None => false,
2041                 }
2042         });
2043
2044     if please_inline {
2045         let mut visited = FxHashSet::default();
2046
2047         let res = Res::Def(DefKind::Mod, crate_def_id);
2048
2049         if let Some(items) = inline::try_inline(
2050             cx,
2051             cx.tcx.parent_module(krate.hir_id()).to_def_id(),
2052             Some(krate.def_id.to_def_id()),
2053             res,
2054             name,
2055             Some(attrs),
2056             &mut visited,
2057         ) {
2058             return items;
2059         }
2060     }
2061
2062     // FIXME: using `from_def_id_and_kind` breaks `rustdoc/masked` for some reason
2063     vec![Item {
2064         name: Some(name),
2065         attrs: box attrs.clean(cx),
2066         item_id: crate_def_id.into(),
2067         visibility: ty_vis.clean(cx),
2068         kind: box ExternCrateItem { src: orig_name },
2069         cfg: attrs.cfg(cx.tcx, &cx.cache.hidden_cfg),
2070     }]
2071 }
2072
2073 fn clean_use_statement<'tcx>(
2074     import: &hir::Item<'tcx>,
2075     name: Symbol,
2076     path: &hir::Path<'tcx>,
2077     kind: hir::UseKind,
2078     cx: &mut DocContext<'tcx>,
2079 ) -> Vec<Item> {
2080     // We need this comparison because some imports (for std types for example)
2081     // are "inserted" as well but directly by the compiler and they should not be
2082     // taken into account.
2083     if import.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
2084         return Vec::new();
2085     }
2086
2087     let visibility = cx.tcx.visibility(import.def_id);
2088     let attrs = cx.tcx.hir().attrs(import.hir_id());
2089     let inline_attr = attrs.lists(sym::doc).get_word_attr(sym::inline);
2090     let pub_underscore = visibility.is_public() && name == kw::Underscore;
2091     let current_mod = cx.tcx.parent_module_from_def_id(import.def_id);
2092
2093     // The parent of the module in which this import resides. This
2094     // is the same as `current_mod` if that's already the top
2095     // level module.
2096     let parent_mod = cx.tcx.parent_module_from_def_id(current_mod);
2097
2098     // This checks if the import can be seen from a higher level module.
2099     // In other words, it checks if the visibility is the equivalent of
2100     // `pub(super)` or higher. If the current module is the top level
2101     // module, there isn't really a parent module, which makes the results
2102     // meaningless. In this case, we make sure the answer is `false`.
2103     let is_visible_from_parent_mod = visibility.is_accessible_from(parent_mod.to_def_id(), cx.tcx)
2104         && !current_mod.is_top_level_module();
2105
2106     if pub_underscore {
2107         if let Some(ref inline) = inline_attr {
2108             rustc_errors::struct_span_err!(
2109                 cx.tcx.sess,
2110                 inline.span(),
2111                 E0780,
2112                 "anonymous imports cannot be inlined"
2113             )
2114             .span_label(import.span, "anonymous import")
2115             .emit();
2116         }
2117     }
2118
2119     // We consider inlining the documentation of `pub use` statements, but we
2120     // forcefully don't inline if this is not public or if the
2121     // #[doc(no_inline)] attribute is present.
2122     // Don't inline doc(hidden) imports so they can be stripped at a later stage.
2123     let mut denied = !(visibility.is_public()
2124         || (cx.render_options.document_private && is_visible_from_parent_mod))
2125         || pub_underscore
2126         || attrs.iter().any(|a| {
2127             a.has_name(sym::doc)
2128                 && match a.meta_item_list() {
2129                     Some(l) => {
2130                         attr::list_contains_name(&l, sym::no_inline)
2131                             || attr::list_contains_name(&l, sym::hidden)
2132                     }
2133                     None => false,
2134                 }
2135         });
2136
2137     // Also check whether imports were asked to be inlined, in case we're trying to re-export a
2138     // crate in Rust 2018+
2139     let path = path.clean(cx);
2140     let inner = if kind == hir::UseKind::Glob {
2141         if !denied {
2142             let mut visited = FxHashSet::default();
2143             if let Some(items) = inline::try_inline_glob(cx, path.res, &mut visited) {
2144                 return items;
2145             }
2146         }
2147         Import::new_glob(resolve_use_source(cx, path), true)
2148     } else {
2149         if inline_attr.is_none() {
2150             if let Res::Def(DefKind::Mod, did) = path.res {
2151                 if !did.is_local() && did.is_crate_root() {
2152                     // if we're `pub use`ing an extern crate root, don't inline it unless we
2153                     // were specifically asked for it
2154                     denied = true;
2155                 }
2156             }
2157         }
2158         if !denied {
2159             let mut visited = FxHashSet::default();
2160             let import_def_id = import.def_id.to_def_id();
2161
2162             if let Some(mut items) = inline::try_inline(
2163                 cx,
2164                 cx.tcx.parent_module(import.hir_id()).to_def_id(),
2165                 Some(import_def_id),
2166                 path.res,
2167                 name,
2168                 Some(attrs),
2169                 &mut visited,
2170             ) {
2171                 items.push(Item::from_def_id_and_parts(
2172                     import_def_id,
2173                     None,
2174                     ImportItem(Import::new_simple(name, resolve_use_source(cx, path), false)),
2175                     cx,
2176                 ));
2177                 return items;
2178             }
2179         }
2180         Import::new_simple(name, resolve_use_source(cx, path), true)
2181     };
2182
2183     vec![Item::from_def_id_and_parts(import.def_id.to_def_id(), None, ImportItem(inner), cx)]
2184 }
2185
2186 fn clean_maybe_renamed_foreign_item<'tcx>(
2187     cx: &mut DocContext<'tcx>,
2188     item: &hir::ForeignItem<'tcx>,
2189     renamed: Option<Symbol>,
2190 ) -> Item {
2191     let def_id = item.def_id.to_def_id();
2192     cx.with_param_env(def_id, |cx| {
2193         let kind = match item.kind {
2194             hir::ForeignItemKind::Fn(decl, names, generics) => {
2195                 let (generics, decl) = enter_impl_trait(cx, |cx| {
2196                     // NOTE: generics must be cleaned before args
2197                     let generics = generics.clean(cx);
2198                     let args = clean_args_from_types_and_names(cx, decl.inputs, names);
2199                     let decl = clean_fn_decl_with_args(cx, decl, args);
2200                     (generics, decl)
2201                 });
2202                 ForeignFunctionItem(Function { decl, generics })
2203             }
2204             hir::ForeignItemKind::Static(ty, mutability) => {
2205                 ForeignStaticItem(Static { type_: ty.clean(cx), mutability, expr: None })
2206             }
2207             hir::ForeignItemKind::Type => ForeignTypeItem,
2208         };
2209
2210         Item::from_hir_id_and_parts(
2211             item.hir_id(),
2212             Some(renamed.unwrap_or(item.ident.name)),
2213             kind,
2214             cx,
2215         )
2216     })
2217 }
2218
2219 impl<'tcx> Clean<'tcx, TypeBinding> for hir::TypeBinding<'tcx> {
2220     fn clean(&self, cx: &mut DocContext<'tcx>) -> TypeBinding {
2221         TypeBinding {
2222             assoc: PathSegment { name: self.ident.name, args: self.gen_args.clean(cx) },
2223             kind: self.kind.clean(cx),
2224         }
2225     }
2226 }
2227
2228 impl<'tcx> Clean<'tcx, TypeBindingKind> for hir::TypeBindingKind<'tcx> {
2229     fn clean(&self, cx: &mut DocContext<'tcx>) -> TypeBindingKind {
2230         match *self {
2231             hir::TypeBindingKind::Equality { ref term } => {
2232                 TypeBindingKind::Equality { term: term.clean(cx) }
2233             }
2234             hir::TypeBindingKind::Constraint { bounds } => TypeBindingKind::Constraint {
2235                 bounds: bounds.iter().filter_map(|b| b.clean(cx)).collect(),
2236             },
2237         }
2238     }
2239 }