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 crate mod cfg;
   7 crate mod inline;
   8 mod simplify;
   9 crate mod types;
  10 crate mod utils;
  11
  12 use rustc_ast as ast;
  13 use rustc_attr as attr;
  14 use rustc_const_eval::const_eval::{is_const_fn, is_unstable_const_fn};
  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, CRATE_DEF_INDEX, LOCAL_CRATE};
  19 use rustc_index::vec::{Idx, IndexVec};
  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, 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_target::spec::abi::Abi;
  30 use rustc_typeck::check::intrinsic::intrinsic_operation_unsafety;
  31 use rustc_typeck::hir_ty_to_ty;
  32
  33 use std::assert_matches::assert_matches;
  34 use std::collections::hash_map::Entry;
  35 use std::default::Default;
  36 use std::hash::Hash;
  37 use std::rc::Rc;
  38 use std::{mem, vec};
  39
  40 use crate::core::{self, DocContext, ImplTraitParam};
  41 use crate::doctree;
  42 use crate::formats::item_type::ItemType;
  43
  44 use utils::*;
  45
  46 crate use utils::{get_auto_trait_and_blanket_impls, krate, register_res};
  47
  48 crate use self::types::FnRetTy::*;
  49 crate use self::types::ItemKind::*;
  50 crate use self::types::SelfTy::*;
  51 crate use self::types::Type::*;
  52 crate use self::types::Visibility::{Inherited, Public};
  53 crate use self::types::*;
  54
  55 crate trait Clean<T> {
  56     fn clean(&self, cx: &mut DocContext<'_>) -> T;
  57 }
  58
  59 impl<T: Clean<U>, U> Clean<Vec<U>> for [T] {
  60     fn clean(&self, cx: &mut DocContext<'_>) -> Vec<U> {
  61         self.iter().map(|x| x.clean(cx)).collect()
  62     }
  63 }
  64
  65 impl<T: Clean<U>, U, V: Idx> Clean<IndexVec<V, U>> for IndexVec<V, T> {
  66     fn clean(&self, cx: &mut DocContext<'_>) -> IndexVec<V, U> {
  67         self.iter().map(|x| x.clean(cx)).collect()
  68     }
  69 }
  70
  71 impl<T: Clean<U>, U> Clean<U> for &T {
  72     fn clean(&self, cx: &mut DocContext<'_>) -> U {
  73         (**self).clean(cx)
  74     }
  75 }
  76
  77 impl<T: Clean<U>, U> Clean<U> for Rc<T> {
  78     fn clean(&self, cx: &mut DocContext<'_>) -> U {
  79         (**self).clean(cx)
  80     }
  81 }
  82
  83 impl<T: Clean<U>, U> Clean<Option<U>> for Option<T> {
  84     fn clean(&self, cx: &mut DocContext<'_>) -> Option<U> {
  85         self.as_ref().map(|v| v.clean(cx))
  86     }
  87 }
  88
  89 impl Clean<Item> for doctree::Module<'_> {
  90     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
  91         let mut items: Vec<Item> = vec![];
  92         items.extend(self.foreigns.iter().map(|x| x.clean(cx)));
  93         items.extend(self.mods.iter().map(|x| x.clean(cx)));
  94         items.extend(self.items.iter().map(|x| x.clean(cx)).flatten());
  95
  96         // determine if we should display the inner contents or
  97         // the outer `mod` item for the source code.
  98
  99         let span = Span::new({
 100             let where_outer = self.where_outer(cx.tcx);
 101             let sm = cx.sess().source_map();
 102             let outer = sm.lookup_char_pos(where_outer.lo());
 103             let inner = sm.lookup_char_pos(self.where_inner.lo());
 104             if outer.file.start_pos == inner.file.start_pos {
 105                 // mod foo { ... }
 106                 where_outer
 107             } else {
 108                 // mod foo; (and a separate SourceFile for the contents)
 109                 self.where_inner
 110             }
 111         });
 112
 113         Item::from_hir_id_and_parts(
 114             self.id,
 115             Some(self.name),
 116             ModuleItem(Module { items, span }),
 117             cx,
 118         )
 119     }
 120 }
 121
 122 impl Clean<Attributes> for [ast::Attribute] {
 123     fn clean(&self, _cx: &mut DocContext<'_>) -> Attributes {
 124         Attributes::from_ast(self, None)
 125     }
 126 }
 127
 128 impl Clean<GenericBound> for hir::GenericBound<'_> {
 129     fn clean(&self, cx: &mut DocContext<'_>) -> GenericBound {
 130         match *self {
 131             hir::GenericBound::Outlives(lt) => GenericBound::Outlives(lt.clean(cx)),
 132             hir::GenericBound::LangItemTrait(lang_item, span, _, generic_args) => {
 133                 let def_id = cx.tcx.require_lang_item(lang_item, Some(span));
 134
 135                 let trait_ref = ty::TraitRef::identity(cx.tcx, def_id).skip_binder();
 136
 137                 let generic_args = generic_args.clean(cx);
 138                 let bindings = match generic_args {
 139                     GenericArgs::AngleBracketed { bindings, .. } => bindings,
 140                     _ => bug!("clean: parenthesized `GenericBound::LangItemTrait`"),
 141                 };
 142
 143                 GenericBound::TraitBound(
 144                     PolyTrait { trait_: (trait_ref, &*bindings).clean(cx), generic_params: vec![] },
 145                     hir::TraitBoundModifier::None,
 146                 )
 147             }
 148             hir::GenericBound::Trait(ref t, modifier) => {
 149                 GenericBound::TraitBound(t.clean(cx), modifier)
 150             }
 151         }
 152     }
 153 }
 154
 155 impl Clean<Path> for (ty::TraitRef<'_>, &[TypeBinding]) {
 156     fn clean(&self, cx: &mut DocContext<'_>) -> Path {
 157         let (trait_ref, bounds) = *self;
 158         let kind = cx.tcx.def_kind(trait_ref.def_id).into();
 159         if !matches!(kind, ItemType::Trait | ItemType::TraitAlias) {
 160             span_bug!(
 161                 cx.tcx.def_span(trait_ref.def_id),
 162                 "`TraitRef` had unexpected kind {:?}",
 163                 kind
 164             );
 165         }
 166         inline::record_extern_fqn(cx, trait_ref.def_id, kind);
 167         let path = external_path(cx, trait_ref.def_id, true, bounds.to_vec(), trait_ref.substs);
 168
 169         debug!("ty::TraitRef\n  subst: {:?}\n", trait_ref.substs);
 170
 171         path
 172     }
 173 }
 174
 175 impl<'tcx> Clean<GenericBound> for ty::TraitRef<'tcx> {
 176     fn clean(&self, cx: &mut DocContext<'_>) -> GenericBound {
 177         GenericBound::TraitBound(
 178             PolyTrait { trait_: (*self, &[][..]).clean(cx), generic_params: vec![] },
 179             hir::TraitBoundModifier::None,
 180         )
 181     }
 182 }
 183
 184 impl Clean<GenericBound> for (ty::PolyTraitRef<'_>, &[TypeBinding]) {
 185     fn clean(&self, cx: &mut DocContext<'_>) -> GenericBound {
 186         let (poly_trait_ref, bounds) = *self;
 187         let poly_trait_ref = poly_trait_ref.lift_to_tcx(cx.tcx).unwrap();
 188
 189         // collect any late bound regions
 190         let late_bound_regions: Vec<_> = cx
 191             .tcx
 192             .collect_referenced_late_bound_regions(&poly_trait_ref)
 193             .into_iter()
 194             .filter_map(|br| match br {
 195                 ty::BrNamed(_, name) => Some(GenericParamDef {
 196                     name,
 197                     kind: GenericParamDefKind::Lifetime { outlives: vec![] },
 198                 }),
 199                 _ => None,
 200             })
 201             .collect();
 202
 203         GenericBound::TraitBound(
 204             PolyTrait {
 205                 trait_: (poly_trait_ref.skip_binder(), bounds).clean(cx),
 206                 generic_params: late_bound_regions,
 207             },
 208             hir::TraitBoundModifier::None,
 209         )
 210     }
 211 }
 212
 213 impl<'tcx> Clean<GenericBound> for ty::PolyTraitRef<'tcx> {
 214     fn clean(&self, cx: &mut DocContext<'_>) -> GenericBound {
 215         (*self, &[][..]).clean(cx)
 216     }
 217 }
 218
 219 impl Clean<Lifetime> for hir::Lifetime {
 220     fn clean(&self, cx: &mut DocContext<'_>) -> Lifetime {
 221         let def = cx.tcx.named_region(self.hir_id);
 222         match def {
 223             Some(
 224                 rl::Region::EarlyBound(_, node_id, _)
 225                 | rl::Region::LateBound(_, _, node_id, _)
 226                 | rl::Region::Free(_, node_id),
 227             ) => {
 228                 if let Some(lt) = cx.lt_substs.get(&node_id).cloned() {
 229                     return lt;
 230                 }
 231             }
 232             _ => {}
 233         }
 234         Lifetime(self.name.ident().name)
 235     }
 236 }
 237
 238 impl Clean<Constant> for hir::ConstArg {
 239     fn clean(&self, cx: &mut DocContext<'_>) -> Constant {
 240         Constant {
 241             type_: cx
 242                 .tcx
 243                 .type_of(cx.tcx.hir().body_owner_def_id(self.value.body).to_def_id())
 244                 .clean(cx),
 245             kind: ConstantKind::Anonymous { body: self.value.body },
 246         }
 247     }
 248 }
 249
 250 impl Clean<Option<Lifetime>> for ty::RegionKind {
 251     fn clean(&self, _cx: &mut DocContext<'_>) -> Option<Lifetime> {
 252         match *self {
 253             ty::ReStatic => Some(Lifetime::statik()),
 254             ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => {
 255                 Some(Lifetime(name))
 256             }
 257             ty::ReEarlyBound(ref data) => Some(Lifetime(data.name)),
 258
 259             ty::ReLateBound(..)
 260             | ty::ReFree(..)
 261             | ty::ReVar(..)
 262             | ty::RePlaceholder(..)
 263             | ty::ReEmpty(_)
 264             | ty::ReErased => {
 265                 debug!("cannot clean region {:?}", self);
 266                 None
 267             }
 268         }
 269     }
 270 }
 271
 272 impl Clean<WherePredicate> for hir::WherePredicate<'_> {
 273     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
 274         match *self {
 275             hir::WherePredicate::BoundPredicate(ref wbp) => {
 276                 let bound_params = wbp
 277                     .bound_generic_params
 278                     .into_iter()
 279                     .map(|param| {
 280                         // Higher-ranked params must be lifetimes.
 281                         // Higher-ranked lifetimes can't have bounds.
 282                         assert_matches!(
 283                             param,
 284                             hir::GenericParam {
 285                                 kind: hir::GenericParamKind::Lifetime { .. },
 286                                 bounds: [],
 287                                 ..
 288                             }
 289                         );
 290                         Lifetime(param.name.ident().name)
 291                     })
 292                     .collect();
 293                 WherePredicate::BoundPredicate {
 294                     ty: wbp.bounded_ty.clean(cx),
 295                     bounds: wbp.bounds.clean(cx),
 296                     bound_params,
 297                 }
 298             }
 299
 300             hir::WherePredicate::RegionPredicate(ref wrp) => WherePredicate::RegionPredicate {
 301                 lifetime: wrp.lifetime.clean(cx),
 302                 bounds: wrp.bounds.clean(cx),
 303             },
 304
 305             hir::WherePredicate::EqPredicate(ref wrp) => {
 306                 WherePredicate::EqPredicate { lhs: wrp.lhs_ty.clean(cx), rhs: wrp.rhs_ty.clean(cx) }
 307             }
 308         }
 309     }
 310 }
 311
 312 impl<'a> Clean<Option<WherePredicate>> for ty::Predicate<'a> {
 313     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 314         let bound_predicate = self.kind();
 315         match bound_predicate.skip_binder() {
 316             ty::PredicateKind::Trait(pred) => Some(bound_predicate.rebind(pred).clean(cx)),
 317             ty::PredicateKind::RegionOutlives(pred) => pred.clean(cx),
 318             ty::PredicateKind::TypeOutlives(pred) => pred.clean(cx),
 319             ty::PredicateKind::Projection(pred) => Some(pred.clean(cx)),
 320             ty::PredicateKind::ConstEvaluatable(..) => None,
 321
 322             ty::PredicateKind::Subtype(..)
 323             | ty::PredicateKind::Coerce(..)
 324             | ty::PredicateKind::WellFormed(..)
 325             | ty::PredicateKind::ObjectSafe(..)
 326             | ty::PredicateKind::ClosureKind(..)
 327             | ty::PredicateKind::ConstEquate(..)
 328             | ty::PredicateKind::TypeWellFormedFromEnv(..) => panic!("not user writable"),
 329         }
 330     }
 331 }
 332
 333 impl<'a> Clean<WherePredicate> for ty::PolyTraitPredicate<'a> {
 334     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
 335         let poly_trait_ref = self.map_bound(|pred| pred.trait_ref);
 336         WherePredicate::BoundPredicate {
 337             ty: poly_trait_ref.skip_binder().self_ty().clean(cx),
 338             bounds: vec![poly_trait_ref.clean(cx)],
 339             bound_params: Vec::new(),
 340         }
 341     }
 342 }
 343
 344 impl<'tcx> Clean<Option<WherePredicate>>
 345     for ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
 346 {
 347     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 348         let ty::OutlivesPredicate(a, b) = self;
 349
 350         if let (ty::ReEmpty(_), ty::ReEmpty(_)) = (a, b) {
 351             return None;
 352         }
 353
 354         Some(WherePredicate::RegionPredicate {
 355             lifetime: a.clean(cx).expect("failed to clean lifetime"),
 356             bounds: vec![GenericBound::Outlives(b.clean(cx).expect("failed to clean bounds"))],
 357         })
 358     }
 359 }
 360
 361 impl<'tcx> Clean<Option<WherePredicate>> for ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>> {
 362     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 363         let ty::OutlivesPredicate(ty, lt) = self;
 364
 365         if let ty::ReEmpty(_) = lt {
 366             return None;
 367         }
 368
 369         Some(WherePredicate::BoundPredicate {
 370             ty: ty.clean(cx),
 371             bounds: vec![GenericBound::Outlives(lt.clean(cx).expect("failed to clean lifetimes"))],
 372             bound_params: Vec::new(),
 373         })
 374     }
 375 }
 376
 377 impl<'tcx> Clean<WherePredicate> for ty::ProjectionPredicate<'tcx> {
 378     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
 379         let ty::ProjectionPredicate { projection_ty, ty } = self;
 380         WherePredicate::EqPredicate { lhs: projection_ty.clean(cx), rhs: ty.clean(cx) }
 381     }
 382 }
 383
 384 impl<'tcx> Clean<Type> for ty::ProjectionTy<'tcx> {
 385     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
 386         let lifted = self.lift_to_tcx(cx.tcx).unwrap();
 387         let trait_ = match lifted.trait_ref(cx.tcx).clean(cx) {
 388             GenericBound::TraitBound(t, _) => t.trait_,
 389             GenericBound::Outlives(_) => panic!("cleaning a trait got a lifetime"),
 390         };
 391         let self_type = self.self_ty().clean(cx);
 392         Type::QPath {
 393             name: cx.tcx.associated_item(self.item_def_id).ident.name,
 394             self_def_id: self_type.def_id(),
 395             self_type: box self_type,
 396             trait_: box trait_,
 397         }
 398     }
 399 }
 400
 401 impl Clean<GenericParamDef> for ty::GenericParamDef {
 402     fn clean(&self, cx: &mut DocContext<'_>) -> GenericParamDef {
 403         let (name, kind) = match self.kind {
 404             ty::GenericParamDefKind::Lifetime => {
 405                 (self.name, GenericParamDefKind::Lifetime { outlives: vec![] })
 406             }
 407             ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
 408                 let default = if has_default {
 409                     let mut default = cx.tcx.type_of(self.def_id).clean(cx);
 410
 411                     // We need to reassign the `self_def_id`, if there's a parent (which is the
 412                     // `Self` type), so we can properly render `<Self as X>` casts, because the
 413                     // information about which type `Self` is, is only present here, but not in
 414                     // the cleaning process of the type itself. To resolve this and have the
 415                     // `self_def_id` set, we override it here.
 416                     // See https://github.com/rust-lang/rust/issues/85454
 417                     if let QPath { ref mut self_def_id, .. } = default {
 418                         *self_def_id = cx.tcx.parent(self.def_id);
 419                     }
 420
 421                     Some(default)
 422                 } else {
 423                     None
 424                 };
 425                 (
 426                     self.name,
 427                     GenericParamDefKind::Type {
 428                         did: self.def_id,
 429                         bounds: vec![], // These are filled in from the where-clauses.
 430                         default,
 431                         synthetic,
 432                     },
 433                 )
 434             }
 435             ty::GenericParamDefKind::Const { has_default, .. } => (
 436                 self.name,
 437                 GenericParamDefKind::Const {
 438                     did: self.def_id,
 439                     ty: cx.tcx.type_of(self.def_id).clean(cx),
 440                     default: match has_default {
 441                         true => Some(cx.tcx.const_param_default(self.def_id).to_string()),
 442                         false => None,
 443                     },
 444                 },
 445             ),
 446         };
 447
 448         GenericParamDef { name, kind }
 449     }
 450 }
 451
 452 impl Clean<GenericParamDef> for hir::GenericParam<'_> {
 453     fn clean(&self, cx: &mut DocContext<'_>) -> GenericParamDef {
 454         let (name, kind) = match self.kind {
 455             hir::GenericParamKind::Lifetime { .. } => {
 456                 let outlives = self
 457                     .bounds
 458                     .iter()
 459                     .map(|bound| match bound {
 460                         hir::GenericBound::Outlives(lt) => lt.clean(cx),
 461                         _ => panic!(),
 462                     })
 463                     .collect();
 464                 (self.name.ident().name, GenericParamDefKind::Lifetime { outlives })
 465             }
 466             hir::GenericParamKind::Type { ref default, synthetic } => (
 467                 self.name.ident().name,
 468                 GenericParamDefKind::Type {
 469                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
 470                     bounds: self.bounds.clean(cx),
 471                     default: default.clean(cx),
 472                     synthetic,
 473                 },
 474             ),
 475             hir::GenericParamKind::Const { ref ty, default } => (
 476                 self.name.ident().name,
 477                 GenericParamDefKind::Const {
 478                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
 479                     ty: ty.clean(cx),
 480                     default: default.map(|ct| {
 481                         let def_id = cx.tcx.hir().local_def_id(ct.hir_id);
 482                         ty::Const::from_anon_const(cx.tcx, def_id).to_string()
 483                     }),
 484                 },
 485             ),
 486         };
 487
 488         GenericParamDef { name, kind }
 489     }
 490 }
 491
 492 impl Clean<Generics> for hir::Generics<'_> {
 493     fn clean(&self, cx: &mut DocContext<'_>) -> Generics {
 494         // Synthetic type-parameters are inserted after normal ones.
 495         // In order for normal parameters to be able to refer to synthetic ones,
 496         // scans them first.
 497         fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
 498             match param.kind {
 499                 hir::GenericParamKind::Type { synthetic, .. } => {
 500                     synthetic == Some(hir::SyntheticTyParamKind::ImplTrait)
 501                 }
 502                 _ => false,
 503             }
 504         }
 505         /// This can happen for `async fn`, e.g. `async fn f<'_>(&'_ self)`.
 506         ///
 507         /// See [`lifetime_to_generic_param`] in [`rustc_ast_lowering`] for more information.
 508         ///
 509         /// [`lifetime_to_generic_param`]: rustc_ast_lowering::LoweringContext::lifetime_to_generic_param
 510         fn is_elided_lifetime(param: &hir::GenericParam<'_>) -> bool {
 511             matches!(
 512                 param.kind,
 513                 hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided }
 514             )
 515         }
 516
 517         let impl_trait_params = self
 518             .params
 519             .iter()
 520             .filter(|param| is_impl_trait(param))
 521             .map(|param| {
 522                 let param: GenericParamDef = param.clean(cx);
 523                 match param.kind {
 524                     GenericParamDefKind::Lifetime { .. } => unreachable!(),
 525                     GenericParamDefKind::Type { did, ref bounds, .. } => {
 526                         cx.impl_trait_bounds.insert(did.into(), bounds.clone());
 527                     }
 528                     GenericParamDefKind::Const { .. } => unreachable!(),
 529                 }
 530                 param
 531             })
 532             .collect::<Vec<_>>();
 533
 534         let mut params = Vec::with_capacity(self.params.len());
 535         for p in self.params.iter().filter(|p| !is_impl_trait(p) && !is_elided_lifetime(p)) {
 536             let p = p.clean(cx);
 537             params.push(p);
 538         }
 539         params.extend(impl_trait_params);
 540
 541         let mut generics =
 542             Generics { params, where_predicates: self.where_clause.predicates.clean(cx) };
 543
 544         // Some duplicates are generated for ?Sized bounds between type params and where
 545         // predicates. The point in here is to move the bounds definitions from type params
 546         // to where predicates when such cases occur.
 547         for where_pred in &mut generics.where_predicates {
 548             match *where_pred {
 549                 WherePredicate::BoundPredicate {
 550                     ty: Generic(ref name), ref mut bounds, ..
 551                 } => {
 552                     if bounds.is_empty() {
 553                         for param in &mut generics.params {
 554                             match param.kind {
 555                                 GenericParamDefKind::Lifetime { .. } => {}
 556                                 GenericParamDefKind::Type { bounds: ref mut ty_bounds, .. } => {
 557                                     if &param.name == name {
 558                                         mem::swap(bounds, ty_bounds);
 559                                         break;
 560                                     }
 561                                 }
 562                                 GenericParamDefKind::Const { .. } => {}
 563                             }
 564                         }
 565                     }
 566                 }
 567                 _ => continue,
 568             }
 569         }
 570         generics
 571     }
 572 }
 573
 574 impl<'a, 'tcx> Clean<Generics> for (&'a ty::Generics, ty::GenericPredicates<'tcx>) {
 575     fn clean(&self, cx: &mut DocContext<'_>) -> Generics {
 576         use self::WherePredicate as WP;
 577         use std::collections::BTreeMap;
 578
 579         let (gens, preds) = *self;
 580
 581         // Don't populate `cx.impl_trait_bounds` before `clean`ning `where` clauses,
 582         // since `Clean for ty::Predicate` would consume them.
 583         let mut impl_trait = BTreeMap::<ImplTraitParam, Vec<GenericBound>>::default();
 584
 585         // Bounds in the type_params and lifetimes fields are repeated in the
 586         // predicates field (see rustc_typeck::collect::ty_generics), so remove
 587         // them.
 588         let stripped_params = gens
 589             .params
 590             .iter()
 591             .filter_map(|param| match param.kind {
 592                 ty::GenericParamDefKind::Lifetime => Some(param.clean(cx)),
 593                 ty::GenericParamDefKind::Type { synthetic, .. } => {
 594                     if param.name == kw::SelfUpper {
 595                         assert_eq!(param.index, 0);
 596                         return None;
 597                     }
 598                     if synthetic == Some(hir::SyntheticTyParamKind::ImplTrait) {
 599                         impl_trait.insert(param.index.into(), vec![]);
 600                         return None;
 601                     }
 602                     Some(param.clean(cx))
 603                 }
 604                 ty::GenericParamDefKind::Const { .. } => Some(param.clean(cx)),
 605             })
 606             .collect::<Vec<GenericParamDef>>();
 607
 608         // param index -> [(DefId of trait, associated type name, type)]
 609         let mut impl_trait_proj = FxHashMap::<u32, Vec<(DefId, Symbol, Ty<'tcx>)>>::default();
 610
 611         let where_predicates = preds
 612             .predicates
 613             .iter()
 614             .flat_map(|(p, _)| {
 615                 let mut projection = None;
 616                 let param_idx = (|| {
 617                     let bound_p = p.kind();
 618                     match bound_p.skip_binder() {
 619                         ty::PredicateKind::Trait(pred) => {
 620                             if let ty::Param(param) = pred.self_ty().kind() {
 621                                 return Some(param.index);
 622                             }
 623                         }
 624                         ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty, _reg)) => {
 625                             if let ty::Param(param) = ty.kind() {
 626                                 return Some(param.index);
 627                             }
 628                         }
 629                         ty::PredicateKind::Projection(p) => {
 630                             if let ty::Param(param) = p.projection_ty.self_ty().kind() {
 631                                 projection = Some(bound_p.rebind(p));
 632                                 return Some(param.index);
 633                             }
 634                         }
 635                         _ => (),
 636                     }
 637
 638                     None
 639                 })();
 640
 641                 if let Some(param_idx) = param_idx {
 642                     if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
 643                         let p = p.clean(cx)?;
 644
 645                         b.extend(
 646                             p.get_bounds()
 647                                 .into_iter()
 648                                 .flatten()
 649                                 .cloned()
 650                                 .filter(|b| !b.is_sized_bound(cx)),
 651                         );
 652
 653                         let proj = projection
 654                             .map(|p| (p.skip_binder().projection_ty.clean(cx), p.skip_binder().ty));
 655                         if let Some(((_, trait_did, name), rhs)) =
 656                             proj.as_ref().and_then(|(lhs, rhs)| Some((lhs.projection()?, rhs)))
 657                         {
 658                             impl_trait_proj
 659                                 .entry(param_idx)
 660                                 .or_default()
 661                                 .push((trait_did, name, rhs));
 662                         }
 663
 664                         return None;
 665                     }
 666                 }
 667
 668                 Some(p)
 669             })
 670             .collect::<Vec<_>>();
 671
 672         for (param, mut bounds) in impl_trait {
 673             // Move trait bounds to the front.
 674             bounds.sort_by_key(|b| !matches!(b, GenericBound::TraitBound(..)));
 675
 676             if let crate::core::ImplTraitParam::ParamIndex(idx) = param {
 677                 if let Some(proj) = impl_trait_proj.remove(&idx) {
 678                     for (trait_did, name, rhs) in proj {
 679                         let rhs = rhs.clean(cx);
 680                         simplify::merge_bounds(cx, &mut bounds, trait_did, name, &rhs);
 681                     }
 682                 }
 683             } else {
 684                 unreachable!();
 685             }
 686
 687             cx.impl_trait_bounds.insert(param, bounds);
 688         }
 689
 690         // Now that `cx.impl_trait_bounds` is populated, we can process
 691         // remaining predicates which could contain `impl Trait`.
 692         let mut where_predicates =
 693             where_predicates.into_iter().flat_map(|p| p.clean(cx)).collect::<Vec<_>>();
 694
 695         // Type parameters have a Sized bound by default unless removed with
 696         // ?Sized. Scan through the predicates and mark any type parameter with
 697         // a Sized bound, removing the bounds as we find them.
 698         //
 699         // Note that associated types also have a sized bound by default, but we
 700         // don't actually know the set of associated types right here so that's
 701         // handled in cleaning associated types
 702         let mut sized_params = FxHashSet::default();
 703         where_predicates.retain(|pred| match *pred {
 704             WP::BoundPredicate { ty: Generic(ref g), ref bounds, .. } => {
 705                 if bounds.iter().any(|b| b.is_sized_bound(cx)) {
 706                     sized_params.insert(*g);
 707                     false
 708                 } else {
 709                     true
 710                 }
 711             }
 712             _ => true,
 713         });
 714
 715         // Run through the type parameters again and insert a ?Sized
 716         // unbound for any we didn't find to be Sized.
 717         for tp in &stripped_params {
 718             if matches!(tp.kind, types::GenericParamDefKind::Type { .. })
 719                 && !sized_params.contains(&tp.name)
 720             {
 721                 where_predicates.push(WP::BoundPredicate {
 722                     ty: Type::Generic(tp.name),
 723                     bounds: vec![GenericBound::maybe_sized(cx)],
 724                     bound_params: Vec::new(),
 725                 })
 726             }
 727         }
 728
 729         // It would be nice to collect all of the bounds on a type and recombine
 730         // them if possible, to avoid e.g., `where T: Foo, T: Bar, T: Sized, T: 'a`
 731         // and instead see `where T: Foo + Bar + Sized + 'a`
 732
 733         Generics {
 734             params: stripped_params,
 735             where_predicates: simplify::where_clauses(cx, where_predicates),
 736         }
 737     }
 738 }
 739
 740 fn clean_fn_or_proc_macro(
 741     item: &hir::Item<'_>,
 742     sig: &'a hir::FnSig<'a>,
 743     generics: &'a hir::Generics<'a>,
 744     body_id: hir::BodyId,
 745     name: &mut Symbol,
 746     cx: &mut DocContext<'_>,
 747 ) -> ItemKind {
 748     let attrs = cx.tcx.hir().attrs(item.hir_id());
 749     let macro_kind = attrs.iter().find_map(|a| {
 750         if a.has_name(sym::proc_macro) {
 751             Some(MacroKind::Bang)
 752         } else if a.has_name(sym::proc_macro_derive) {
 753             Some(MacroKind::Derive)
 754         } else if a.has_name(sym::proc_macro_attribute) {
 755             Some(MacroKind::Attr)
 756         } else {
 757             None
 758         }
 759     });
 760     match macro_kind {
 761         Some(kind) => {
 762             if kind == MacroKind::Derive {
 763                 *name = attrs
 764                     .lists(sym::proc_macro_derive)
 765                     .find_map(|mi| mi.ident())
 766                     .expect("proc-macro derives require a name")
 767                     .name;
 768             }
 769
 770             let mut helpers = Vec::new();
 771             for mi in attrs.lists(sym::proc_macro_derive) {
 772                 if !mi.has_name(sym::attributes) {
 773                     continue;
 774                 }
 775
 776                 if let Some(list) = mi.meta_item_list() {
 777                     for inner_mi in list {
 778                         if let Some(ident) = inner_mi.ident() {
 779                             helpers.push(ident.name);
 780                         }
 781                     }
 782                 }
 783             }
 784             ProcMacroItem(ProcMacro { kind, helpers })
 785         }
 786         None => {
 787             let mut func = (sig, generics, body_id).clean(cx);
 788             let def_id = item.def_id.to_def_id();
 789             func.header.constness =
 790                 if is_const_fn(cx.tcx, def_id) && is_unstable_const_fn(cx.tcx, def_id).is_none() {
 791                     hir::Constness::Const
 792                 } else {
 793                     hir::Constness::NotConst
 794                 };
 795             FunctionItem(func)
 796         }
 797     }
 798 }
 799
 800 impl<'a> Clean<Function> for (&'a hir::FnSig<'a>, &'a hir::Generics<'a>, hir::BodyId) {
 801     fn clean(&self, cx: &mut DocContext<'_>) -> Function {
 802         let (generics, decl) =
 803             enter_impl_trait(cx, |cx| (self.1.clean(cx), (&*self.0.decl, self.2).clean(cx)));
 804         Function { decl, generics, header: self.0.header }
 805     }
 806 }
 807
 808 impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], &'a [Ident]) {
 809     fn clean(&self, cx: &mut DocContext<'_>) -> Arguments {
 810         Arguments {
 811             values: self
 812                 .0
 813                 .iter()
 814                 .enumerate()
 815                 .map(|(i, ty)| {
 816                     let mut name = self.1.get(i).map_or(kw::Empty, |ident| ident.name);
 817                     if name.is_empty() {
 818                         name = kw::Underscore;
 819                     }
 820                     Argument { name, type_: ty.clean(cx) }
 821                 })
 822                 .collect(),
 823         }
 824     }
 825 }
 826
 827 impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], hir::BodyId) {
 828     fn clean(&self, cx: &mut DocContext<'_>) -> Arguments {
 829         let body = cx.tcx.hir().body(self.1);
 830
 831         Arguments {
 832             values: self
 833                 .0
 834                 .iter()
 835                 .enumerate()
 836                 .map(|(i, ty)| Argument {
 837                     name: name_from_pat(&body.params[i].pat),
 838                     type_: ty.clean(cx),
 839                 })
 840                 .collect(),
 841         }
 842     }
 843 }
 844
 845 impl<'a, A: Copy> Clean<FnDecl> for (&'a hir::FnDecl<'a>, A)
 846 where
 847     (&'a [hir::Ty<'a>], A): Clean<Arguments>,
 848 {
 849     fn clean(&self, cx: &mut DocContext<'_>) -> FnDecl {
 850         FnDecl {
 851             inputs: (self.0.inputs, self.1).clean(cx),
 852             output: self.0.output.clean(cx),
 853             c_variadic: self.0.c_variadic,
 854         }
 855     }
 856 }
 857
 858 impl<'tcx> Clean<FnDecl> for (DefId, ty::PolyFnSig<'tcx>) {
 859     fn clean(&self, cx: &mut DocContext<'_>) -> FnDecl {
 860         let (did, sig) = *self;
 861         let mut names = if did.is_local() { &[] } else { cx.tcx.fn_arg_names(did) }.iter();
 862
 863         FnDecl {
 864             output: Return(sig.skip_binder().output().clean(cx)),
 865             c_variadic: sig.skip_binder().c_variadic,
 866             inputs: Arguments {
 867                 values: sig
 868                     .skip_binder()
 869                     .inputs()
 870                     .iter()
 871                     .map(|t| Argument {
 872                         type_: t.clean(cx),
 873                         name: names.next().map_or(kw::Empty, |i| i.name),
 874                     })
 875                     .collect(),
 876             },
 877         }
 878     }
 879 }
 880
 881 impl Clean<FnRetTy> for hir::FnRetTy<'_> {
 882     fn clean(&self, cx: &mut DocContext<'_>) -> FnRetTy {
 883         match *self {
 884             Self::Return(ref typ) => Return(typ.clean(cx)),
 885             Self::DefaultReturn(..) => DefaultReturn,
 886         }
 887     }
 888 }
 889
 890 impl Clean<bool> for hir::IsAuto {
 891     fn clean(&self, _: &mut DocContext<'_>) -> bool {
 892         match *self {
 893             hir::IsAuto::Yes => true,
 894             hir::IsAuto::No => false,
 895         }
 896     }
 897 }
 898
 899 impl Clean<Type> for hir::TraitRef<'_> {
 900     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
 901         let path = self.path.clean(cx);
 902         resolve_type(cx, path)
 903     }
 904 }
 905
 906 impl Clean<Path> for hir::TraitRef<'_> {
 907     fn clean(&self, cx: &mut DocContext<'_>) -> Path {
 908         let path = self.path.clean(cx);
 909         register_res(cx, path.res);
 910         path
 911     }
 912 }
 913
 914 impl Clean<PolyTrait> for hir::PolyTraitRef<'_> {
 915     fn clean(&self, cx: &mut DocContext<'_>) -> PolyTrait {
 916         PolyTrait {
 917             trait_: self.trait_ref.clean(cx),
 918             generic_params: self.bound_generic_params.clean(cx),
 919         }
 920     }
 921 }
 922
 923 impl Clean<Item> for hir::TraitItem<'_> {
 924     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
 925         let local_did = self.def_id.to_def_id();
 926         cx.with_param_env(local_did, |cx| {
 927             let inner = match self.kind {
 928                 hir::TraitItemKind::Const(ref ty, default) => {
 929                     AssocConstItem(ty.clean(cx), default.map(|e| print_const_expr(cx.tcx, e)))
 930                 }
 931                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
 932                     let mut m = (sig, &self.generics, body).clean(cx);
 933                     if m.header.constness == hir::Constness::Const
 934                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
 935                     {
 936                         m.header.constness = hir::Constness::NotConst;
 937                     }
 938                     MethodItem(m, None)
 939                 }
 940                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(ref names)) => {
 941                     let (generics, decl) = enter_impl_trait(cx, |cx| {
 942                         (self.generics.clean(cx), (&*sig.decl, &names[..]).clean(cx))
 943                     });
 944                     let mut t = Function { header: sig.header, decl, generics };
 945                     if t.header.constness == hir::Constness::Const
 946                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
 947                     {
 948                         t.header.constness = hir::Constness::NotConst;
 949                     }
 950                     TyMethodItem(t)
 951                 }
 952                 hir::TraitItemKind::Type(ref bounds, ref default) => {
 953                     AssocTypeItem(bounds.clean(cx), default.clean(cx))
 954                 }
 955             };
 956             let what_rustc_thinks =
 957                 Item::from_def_id_and_parts(local_did, Some(self.ident.name), inner, cx);
 958             // Trait items always inherit the trait's visibility -- we don't want to show `pub`.
 959             Item { visibility: Inherited, ..what_rustc_thinks }
 960         })
 961     }
 962 }
 963
 964 impl Clean<Item> for hir::ImplItem<'_> {
 965     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
 966         let local_did = self.def_id.to_def_id();
 967         cx.with_param_env(local_did, |cx| {
 968             let inner = match self.kind {
 969                 hir::ImplItemKind::Const(ref ty, expr) => {
 970                     AssocConstItem(ty.clean(cx), Some(print_const_expr(cx.tcx, expr)))
 971                 }
 972                 hir::ImplItemKind::Fn(ref sig, body) => {
 973                     let mut m = (sig, &self.generics, body).clean(cx);
 974                     if m.header.constness == hir::Constness::Const
 975                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
 976                     {
 977                         m.header.constness = hir::Constness::NotConst;
 978                     }
 979                     MethodItem(m, Some(self.defaultness))
 980                 }
 981                 hir::ImplItemKind::TyAlias(ref hir_ty) => {
 982                     let type_ = hir_ty.clean(cx);
 983                     let item_type = hir_ty_to_ty(cx.tcx, hir_ty).clean(cx);
 984                     TypedefItem(
 985                         Typedef {
 986                             type_,
 987                             generics: Generics::default(),
 988                             item_type: Some(item_type),
 989                         },
 990                         true,
 991                     )
 992                 }
 993             };
 994
 995             let what_rustc_thinks =
 996                 Item::from_def_id_and_parts(local_did, Some(self.ident.name), inner, cx);
 997             let parent_item = cx.tcx.hir().expect_item(cx.tcx.hir().get_parent_item(self.hir_id()));
 998             if let hir::ItemKind::Impl(impl_) = &parent_item.kind {
 999                 if impl_.of_trait.is_some() {
1000                     // Trait impl items always inherit the impl's visibility --
1001                     // we don't want to show `pub`.
1002                     Item { visibility: Inherited, ..what_rustc_thinks }
1003                 } else {
1004                     what_rustc_thinks
1005                 }
1006             } else {
1007                 panic!("found impl item with non-impl parent {:?}", parent_item);
1008             }
1009         })
1010     }
1011 }
1012
1013 impl Clean<Item> for ty::AssocItem {
1014     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1015         let tcx = cx.tcx;
1016         let kind = match self.kind {
1017             ty::AssocKind::Const => {
1018                 let ty = tcx.type_of(self.def_id);
1019                 let default = if self.defaultness.has_value() {
1020                     Some(inline::print_inlined_const(tcx, self.def_id))
1021                 } else {
1022                     None
1023                 };
1024                 AssocConstItem(ty.clean(cx), default)
1025             }
1026             ty::AssocKind::Fn => {
1027                 let generics =
1028                     (tcx.generics_of(self.def_id), tcx.explicit_predicates_of(self.def_id))
1029                         .clean(cx);
1030                 let sig = tcx.fn_sig(self.def_id);
1031                 let mut decl = (self.def_id, sig).clean(cx);
1032
1033                 if self.fn_has_self_parameter {
1034                     let self_ty = match self.container {
1035                         ty::ImplContainer(def_id) => tcx.type_of(def_id),
1036                         ty::TraitContainer(_) => tcx.types.self_param,
1037                     };
1038                     let self_arg_ty = sig.input(0).skip_binder();
1039                     if self_arg_ty == self_ty {
1040                         decl.inputs.values[0].type_ = Generic(kw::SelfUpper);
1041                     } else if let ty::Ref(_, ty, _) = *self_arg_ty.kind() {
1042                         if ty == self_ty {
1043                             match decl.inputs.values[0].type_ {
1044                                 BorrowedRef { ref mut type_, .. } => {
1045                                     **type_ = Generic(kw::SelfUpper)
1046                                 }
1047                                 _ => unreachable!(),
1048                             }
1049                         }
1050                     }
1051                 }
1052
1053                 let provided = match self.container {
1054                     ty::ImplContainer(_) => true,
1055                     ty::TraitContainer(_) => self.defaultness.has_value(),
1056                 };
1057                 if provided {
1058                     let constness = if tcx.is_const_fn_raw(self.def_id) {
1059                         hir::Constness::Const
1060                     } else {
1061                         hir::Constness::NotConst
1062                     };
1063                     let asyncness = tcx.asyncness(self.def_id);
1064                     let defaultness = match self.container {
1065                         ty::ImplContainer(_) => Some(self.defaultness),
1066                         ty::TraitContainer(_) => None,
1067                     };
1068                     MethodItem(
1069                         Function {
1070                             generics,
1071                             decl,
1072                             header: hir::FnHeader {
1073                                 unsafety: sig.unsafety(),
1074                                 abi: sig.abi(),
1075                                 constness,
1076                                 asyncness,
1077                             },
1078                         },
1079                         defaultness,
1080                     )
1081                 } else {
1082                     TyMethodItem(Function {
1083                         generics,
1084                         decl,
1085                         header: hir::FnHeader {
1086                             unsafety: sig.unsafety(),
1087                             abi: sig.abi(),
1088                             constness: hir::Constness::NotConst,
1089                             asyncness: hir::IsAsync::NotAsync,
1090                         },
1091                     })
1092                 }
1093             }
1094             ty::AssocKind::Type => {
1095                 let my_name = self.ident.name;
1096
1097                 if let ty::TraitContainer(_) = self.container {
1098                     let bounds = tcx.explicit_item_bounds(self.def_id);
1099                     let predicates = ty::GenericPredicates { parent: None, predicates: bounds };
1100                     let generics = (tcx.generics_of(self.def_id), predicates).clean(cx);
1101                     let mut bounds = generics
1102                         .where_predicates
1103                         .iter()
1104                         .filter_map(|pred| {
1105                             let (name, self_type, trait_, bounds) = match *pred {
1106                                 WherePredicate::BoundPredicate {
1107                                     ty: QPath { ref name, ref self_type, ref trait_, .. },
1108                                     ref bounds,
1109                                     ..
1110                                 } => (name, self_type, trait_, bounds),
1111                                 _ => return None,
1112                             };
1113                             if *name != my_name {
1114                                 return None;
1115                             }
1116                             if trait_.res.def_id() != self.container.id() {
1117                                 return None;
1118                             }
1119                             match **self_type {
1120                                 Generic(ref s) if *s == kw::SelfUpper => {}
1121                                 _ => return None,
1122                             }
1123                             Some(bounds)
1124                         })
1125                         .flat_map(|i| i.iter().cloned())
1126                         .collect::<Vec<_>>();
1127                     // Our Sized/?Sized bound didn't get handled when creating the generics
1128                     // because we didn't actually get our whole set of bounds until just now
1129                     // (some of them may have come from the trait). If we do have a sized
1130                     // bound, we remove it, and if we don't then we add the `?Sized` bound
1131                     // at the end.
1132                     match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1133                         Some(i) => {
1134                             bounds.remove(i);
1135                         }
1136                         None => bounds.push(GenericBound::maybe_sized(cx)),
1137                     }
1138
1139                     let ty = if self.defaultness.has_value() {
1140                         Some(tcx.type_of(self.def_id))
1141                     } else {
1142                         None
1143                     };
1144
1145                     AssocTypeItem(bounds, ty.clean(cx))
1146                 } else {
1147                     // FIXME: when could this happen? Associated items in inherent impls?
1148                     let type_ = tcx.type_of(self.def_id).clean(cx);
1149                     TypedefItem(
1150                         Typedef {
1151                             type_,
1152                             generics: Generics { params: Vec::new(), where_predicates: Vec::new() },
1153                             item_type: None,
1154                         },
1155                         true,
1156                     )
1157                 }
1158             }
1159         };
1160
1161         Item::from_def_id_and_parts(self.def_id, Some(self.ident.name), kind, cx)
1162     }
1163 }
1164
1165 fn clean_qpath(hir_ty: &hir::Ty<'_>, cx: &mut DocContext<'_>) -> Type {
1166     use rustc_hir::GenericParamCount;
1167     let hir::Ty { hir_id: _, span, ref kind } = *hir_ty;
1168     let qpath = match kind {
1169         hir::TyKind::Path(qpath) => qpath,
1170         _ => unreachable!(),
1171     };
1172
1173     match qpath {
1174         hir::QPath::Resolved(None, ref path) => {
1175             if let Res::Def(DefKind::TyParam, did) = path.res {
1176                 if let Some(new_ty) = cx.ty_substs.get(&did).cloned() {
1177                     return new_ty;
1178                 }
1179                 if let Some(bounds) = cx.impl_trait_bounds.remove(&did.into()) {
1180                     return ImplTrait(bounds);
1181                 }
1182             }
1183
1184             let mut alias = None;
1185             if let Res::Def(DefKind::TyAlias, def_id) = path.res {
1186                 // Substitute private type aliases
1187                 if let Some(def_id) = def_id.as_local() {
1188                     let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
1189                     if !cx.cache.access_levels.is_exported(def_id.to_def_id()) {
1190                         alias = Some(&cx.tcx.hir().expect_item(hir_id).kind);
1191                     }
1192                 }
1193             };
1194
1195             if let Some(&hir::ItemKind::TyAlias(ref ty, ref generics)) = alias {
1196                 let provided_params = &path.segments.last().expect("segments were empty");
1197                 let mut ty_substs = FxHashMap::default();
1198                 let mut lt_substs = FxHashMap::default();
1199                 let mut ct_substs = FxHashMap::default();
1200                 let generic_args = provided_params.args();
1201                 {
1202                     let mut indices: GenericParamCount = Default::default();
1203                     for param in generics.params.iter() {
1204                         match param.kind {
1205                             hir::GenericParamKind::Lifetime { .. } => {
1206                                 let mut j = 0;
1207                                 let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1208                                     hir::GenericArg::Lifetime(lt) => {
1209                                         if indices.lifetimes == j {
1210                                             return Some(lt);
1211                                         }
1212                                         j += 1;
1213                                         None
1214                                     }
1215                                     _ => None,
1216                                 });
1217                                 if let Some(lt) = lifetime.cloned() {
1218                                     let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1219                                     let cleaned = if !lt.is_elided() {
1220                                         lt.clean(cx)
1221                                     } else {
1222                                         self::types::Lifetime::elided()
1223                                     };
1224                                     lt_substs.insert(lt_def_id.to_def_id(), cleaned);
1225                                 }
1226                                 indices.lifetimes += 1;
1227                             }
1228                             hir::GenericParamKind::Type { ref default, .. } => {
1229                                 let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1230                                 let mut j = 0;
1231                                 let type_ = generic_args.args.iter().find_map(|arg| match arg {
1232                                     hir::GenericArg::Type(ty) => {
1233                                         if indices.types == j {
1234                                             return Some(ty);
1235                                         }
1236                                         j += 1;
1237                                         None
1238                                     }
1239                                     _ => None,
1240                                 });
1241                                 if let Some(ty) = type_ {
1242                                     ty_substs.insert(ty_param_def_id.to_def_id(), ty.clean(cx));
1243                                 } else if let Some(default) = *default {
1244                                     ty_substs
1245                                         .insert(ty_param_def_id.to_def_id(), default.clean(cx));
1246                                 }
1247                                 indices.types += 1;
1248                             }
1249                             hir::GenericParamKind::Const { .. } => {
1250                                 let const_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1251                                 let mut j = 0;
1252                                 let const_ = generic_args.args.iter().find_map(|arg| match arg {
1253                                     hir::GenericArg::Const(ct) => {
1254                                         if indices.consts == j {
1255                                             return Some(ct);
1256                                         }
1257                                         j += 1;
1258                                         None
1259                                     }
1260                                     _ => None,
1261                                 });
1262                                 if let Some(ct) = const_ {
1263                                     ct_substs.insert(const_param_def_id.to_def_id(), ct.clean(cx));
1264                                 }
1265                                 // FIXME(const_generics_defaults)
1266                                 indices.consts += 1;
1267                             }
1268                         }
1269                     }
1270                 }
1271                 return cx.enter_alias(ty_substs, lt_substs, ct_substs, |cx| ty.clean(cx));
1272             }
1273             let path = path.clean(cx);
1274             resolve_type(cx, path)
1275         }
1276         hir::QPath::Resolved(Some(ref qself), ref p) => {
1277             // Try to normalize `<X as Y>::T` to a type
1278             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1279             if let Some(normalized_value) = normalize(cx, ty) {
1280                 return normalized_value.clean(cx);
1281             }
1282
1283             let segments = if p.is_global() { &p.segments[1..] } else { &p.segments };
1284             let trait_segments = &segments[..segments.len() - 1];
1285             let trait_def = cx.tcx.associated_item(p.res.def_id()).container.id();
1286             let trait_path = self::Path {
1287                 res: Res::Def(DefKind::Trait, trait_def),
1288                 segments: trait_segments.clean(cx),
1289             };
1290             register_res(cx, trait_path.res);
1291             Type::QPath {
1292                 name: p.segments.last().expect("segments were empty").ident.name,
1293                 self_def_id: Some(DefId::local(qself.hir_id.owner.local_def_index)),
1294                 self_type: box qself.clean(cx),
1295                 trait_: box trait_path,
1296             }
1297         }
1298         hir::QPath::TypeRelative(ref qself, ref segment) => {
1299             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1300             let res = match ty.kind() {
1301                 ty::Projection(proj) => Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id),
1302                 // Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
1303                 ty::Error(_) => return Type::Infer,
1304                 _ => bug!("clean: expected associated type, found `{:?}`", ty),
1305             };
1306             let trait_path = hir::Path { span, res, segments: &[] }.clean(cx);
1307             register_res(cx, trait_path.res);
1308             Type::QPath {
1309                 name: segment.ident.name,
1310                 self_def_id: res.opt_def_id(),
1311                 self_type: box qself.clean(cx),
1312                 trait_: box trait_path,
1313             }
1314         }
1315         hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1316     }
1317 }
1318
1319 impl Clean<Type> for hir::Ty<'_> {
1320     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
1321         use rustc_hir::*;
1322
1323         match self.kind {
1324             TyKind::Never => Primitive(PrimitiveType::Never),
1325             TyKind::Ptr(ref m) => RawPointer(m.mutbl, box m.ty.clean(cx)),
1326             TyKind::Rptr(ref l, ref m) => {
1327                 // There are two times a `Fresh` lifetime can be created:
1328                 // 1. For `&'_ x`, written by the user. This corresponds to `lower_lifetime` in `rustc_ast_lowering`.
1329                 // 2. For `&x` as a parameter to an `async fn`. This corresponds to `elided_ref_lifetime in `rustc_ast_lowering`.
1330                 //    See #59286 for more information.
1331                 // Ideally we would only hide the `'_` for case 2., but I don't know a way to distinguish it.
1332                 // Turning `fn f(&'_ self)` into `fn f(&self)` isn't the worst thing in the world, though;
1333                 // there's no case where it could cause the function to fail to compile.
1334                 let elided =
1335                     l.is_elided() || matches!(l.name, LifetimeName::Param(ParamName::Fresh(_)));
1336                 let lifetime = if elided { None } else { Some(l.clean(cx)) };
1337                 BorrowedRef { lifetime, mutability: m.mutbl, type_: box m.ty.clean(cx) }
1338             }
1339             TyKind::Slice(ref ty) => Slice(box ty.clean(cx)),
1340             TyKind::Array(ref ty, ref length) => {
1341                 let def_id = cx.tcx.hir().local_def_id(length.hir_id);
1342                 // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1343                 // as we currently do not supply the parent generics to anonymous constants
1344                 // but do allow `ConstKind::Param`.
1345                 //
1346                 // `const_eval_poly` tries to to first substitute generic parameters which
1347                 // results in an ICE while manually constructing the constant and using `eval`
1348                 // does nothing for `ConstKind::Param`.
1349                 let ct = ty::Const::from_anon_const(cx.tcx, def_id);
1350                 let param_env = cx.tcx.param_env(def_id);
1351                 let length = print_const(cx, ct.eval(cx.tcx, param_env));
1352                 Array(box ty.clean(cx), length)
1353             }
1354             TyKind::Tup(ref tys) => Tuple(tys.clean(cx)),
1355             TyKind::OpaqueDef(item_id, _) => {
1356                 let item = cx.tcx.hir().item(item_id);
1357                 if let hir::ItemKind::OpaqueTy(ref ty) = item.kind {
1358                     ImplTrait(ty.bounds.clean(cx))
1359                 } else {
1360                     unreachable!()
1361                 }
1362             }
1363             TyKind::Path(_) => clean_qpath(&self, cx),
1364             TyKind::TraitObject(ref bounds, ref lifetime, _) => {
1365                 let bounds = bounds.iter().map(|bound| bound.clean(cx)).collect();
1366                 let lifetime = if !lifetime.is_elided() { Some(lifetime.clean(cx)) } else { None };
1367                 DynTrait(bounds, lifetime)
1368             }
1369             TyKind::BareFn(ref barefn) => BareFunction(box barefn.clean(cx)),
1370             // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
1371             TyKind::Infer | TyKind::Err => Infer,
1372             TyKind::Typeof(..) => panic!("unimplemented type {:?}", self.kind),
1373         }
1374     }
1375 }
1376
1377 /// Returns `None` if the type could not be normalized
1378 fn normalize(cx: &mut DocContext<'tcx>, ty: Ty<'_>) -> Option<Ty<'tcx>> {
1379     // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1380     if !cx.tcx.sess.opts.debugging_opts.normalize_docs {
1381         return None;
1382     }
1383
1384     use crate::rustc_trait_selection::infer::TyCtxtInferExt;
1385     use crate::rustc_trait_selection::traits::query::normalize::AtExt;
1386     use rustc_middle::traits::ObligationCause;
1387
1388     // Try to normalize `<X as Y>::T` to a type
1389     let lifted = ty.lift_to_tcx(cx.tcx).unwrap();
1390     let normalized = cx.tcx.infer_ctxt().enter(|infcx| {
1391         infcx
1392             .at(&ObligationCause::dummy(), cx.param_env)
1393             .normalize(lifted)
1394             .map(|resolved| infcx.resolve_vars_if_possible(resolved.value))
1395     });
1396     match normalized {
1397         Ok(normalized_value) => {
1398             debug!("normalized {:?} to {:?}", ty, normalized_value);
1399             Some(normalized_value)
1400         }
1401         Err(err) => {
1402             debug!("failed to normalize {:?}: {:?}", ty, err);
1403             None
1404         }
1405     }
1406 }
1407
1408 impl<'tcx> Clean<Type> for Ty<'tcx> {
1409     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
1410         trace!("cleaning type: {:?}", self);
1411         let ty = normalize(cx, self).unwrap_or(self);
1412         match *ty.kind() {
1413             ty::Never => Primitive(PrimitiveType::Never),
1414             ty::Bool => Primitive(PrimitiveType::Bool),
1415             ty::Char => Primitive(PrimitiveType::Char),
1416             ty::Int(int_ty) => Primitive(int_ty.into()),
1417             ty::Uint(uint_ty) => Primitive(uint_ty.into()),
1418             ty::Float(float_ty) => Primitive(float_ty.into()),
1419             ty::Str => Primitive(PrimitiveType::Str),
1420             ty::Slice(ty) => Slice(box ty.clean(cx)),
1421             ty::Array(ty, n) => {
1422                 let mut n = cx.tcx.lift(n).expect("array lift failed");
1423                 n = n.eval(cx.tcx, ty::ParamEnv::reveal_all());
1424                 let n = print_const(cx, n);
1425                 Array(box ty.clean(cx), n)
1426             }
1427             ty::RawPtr(mt) => RawPointer(mt.mutbl, box mt.ty.clean(cx)),
1428             ty::Ref(r, ty, mutbl) => {
1429                 BorrowedRef { lifetime: r.clean(cx), mutability: mutbl, type_: box ty.clean(cx) }
1430             }
1431             ty::FnDef(..) | ty::FnPtr(_) => {
1432                 let ty = cx.tcx.lift(*self).expect("FnPtr lift failed");
1433                 let sig = ty.fn_sig(cx.tcx);
1434                 let def_id = DefId::local(CRATE_DEF_INDEX);
1435                 BareFunction(box BareFunctionDecl {
1436                     unsafety: sig.unsafety(),
1437                     generic_params: Vec::new(),
1438                     decl: (def_id, sig).clean(cx),
1439                     abi: sig.abi(),
1440                 })
1441             }
1442             ty::Adt(def, substs) => {
1443                 let did = def.did;
1444                 let kind = match def.adt_kind() {
1445                     AdtKind::Struct => ItemType::Struct,
1446                     AdtKind::Union => ItemType::Union,
1447                     AdtKind::Enum => ItemType::Enum,
1448                 };
1449                 inline::record_extern_fqn(cx, did, kind);
1450                 let path = external_path(cx, did, false, vec![], substs);
1451                 ResolvedPath { path, did }
1452             }
1453             ty::Foreign(did) => {
1454                 inline::record_extern_fqn(cx, did, ItemType::ForeignType);
1455                 let path = external_path(cx, did, false, vec![], InternalSubsts::empty());
1456                 ResolvedPath { path, did }
1457             }
1458             ty::Dynamic(ref obj, ref reg) => {
1459                 // HACK: pick the first `did` as the `did` of the trait object. Someone
1460                 // might want to implement "native" support for marker-trait-only
1461                 // trait objects.
1462                 let mut dids = obj.principal_def_id().into_iter().chain(obj.auto_traits());
1463                 let did = dids
1464                     .next()
1465                     .unwrap_or_else(|| panic!("found trait object `{:?}` with no traits?", self));
1466                 let substs = match obj.principal() {
1467                     Some(principal) => principal.skip_binder().substs,
1468                     // marker traits have no substs.
1469                     _ => cx.tcx.intern_substs(&[]),
1470                 };
1471
1472                 inline::record_extern_fqn(cx, did, ItemType::Trait);
1473
1474                 let lifetime = reg.clean(cx);
1475                 let mut bounds = vec![];
1476
1477                 for did in dids {
1478                     let empty = cx.tcx.intern_substs(&[]);
1479                     let path = external_path(cx, did, false, vec![], empty);
1480                     inline::record_extern_fqn(cx, did, ItemType::Trait);
1481                     let bound = PolyTrait { trait_: path, generic_params: Vec::new() };
1482                     bounds.push(bound);
1483                 }
1484
1485                 let mut bindings = vec![];
1486                 for pb in obj.projection_bounds() {
1487                     bindings.push(TypeBinding {
1488                         name: cx.tcx.associated_item(pb.item_def_id()).ident.name,
1489                         kind: TypeBindingKind::Equality { ty: pb.skip_binder().ty.clean(cx) },
1490                     });
1491                 }
1492
1493                 let path = external_path(cx, did, false, bindings, substs);
1494                 bounds.insert(0, PolyTrait { trait_: path, generic_params: Vec::new() });
1495
1496                 DynTrait(bounds, lifetime)
1497             }
1498             ty::Tuple(ref t) => {
1499                 Tuple(t.iter().map(|t| t.expect_ty()).collect::<Vec<_>>().clean(cx))
1500             }
1501
1502             ty::Projection(ref data) => data.clean(cx),
1503
1504             ty::Param(ref p) => {
1505                 if let Some(bounds) = cx.impl_trait_bounds.remove(&p.index.into()) {
1506                     ImplTrait(bounds)
1507                 } else {
1508                     Generic(p.name)
1509                 }
1510             }
1511
1512             ty::Opaque(def_id, substs) => {
1513                 // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1514                 // by looking up the bounds associated with the def_id.
1515                 let substs = cx.tcx.lift(substs).expect("Opaque lift failed");
1516                 let bounds = cx
1517                     .tcx
1518                     .explicit_item_bounds(def_id)
1519                     .iter()
1520                     .map(|(bound, _)| bound.subst(cx.tcx, substs))
1521                     .collect::<Vec<_>>();
1522                 let mut regions = vec![];
1523                 let mut has_sized = false;
1524                 let mut bounds = bounds
1525                     .iter()
1526                     .filter_map(|bound| {
1527                         let bound_predicate = bound.kind();
1528                         let trait_ref = match bound_predicate.skip_binder() {
1529                             ty::PredicateKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
1530                             ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
1531                                 if let Some(r) = reg.clean(cx) {
1532                                     regions.push(GenericBound::Outlives(r));
1533                                 }
1534                                 return None;
1535                             }
1536                             _ => return None,
1537                         };
1538
1539                         if let Some(sized) = cx.tcx.lang_items().sized_trait() {
1540                             if trait_ref.def_id() == sized {
1541                                 has_sized = true;
1542                                 return None;
1543                             }
1544                         }
1545
1546                         let bounds: Vec<_> = bounds
1547                             .iter()
1548                             .filter_map(|bound| {
1549                                 if let ty::PredicateKind::Projection(proj) =
1550                                     bound.kind().skip_binder()
1551                                 {
1552                                     if proj.projection_ty.trait_ref(cx.tcx)
1553                                         == trait_ref.skip_binder()
1554                                     {
1555                                         Some(TypeBinding {
1556                                             name: cx
1557                                                 .tcx
1558                                                 .associated_item(proj.projection_ty.item_def_id)
1559                                                 .ident
1560                                                 .name,
1561                                             kind: TypeBindingKind::Equality {
1562                                                 ty: proj.ty.clean(cx),
1563                                             },
1564                                         })
1565                                     } else {
1566                                         None
1567                                     }
1568                                 } else {
1569                                     None
1570                                 }
1571                             })
1572                             .collect();
1573
1574                         Some((trait_ref, &bounds[..]).clean(cx))
1575                     })
1576                     .collect::<Vec<_>>();
1577                 bounds.extend(regions);
1578                 if !has_sized && !bounds.is_empty() {
1579                     bounds.insert(0, GenericBound::maybe_sized(cx));
1580                 }
1581                 ImplTrait(bounds)
1582             }
1583
1584             ty::Closure(..) | ty::Generator(..) => Tuple(vec![]), // FIXME(pcwalton)
1585
1586             ty::Bound(..) => panic!("Bound"),
1587             ty::Placeholder(..) => panic!("Placeholder"),
1588             ty::GeneratorWitness(..) => panic!("GeneratorWitness"),
1589             ty::Infer(..) => panic!("Infer"),
1590             ty::Error(_) => panic!("Error"),
1591         }
1592     }
1593 }
1594
1595 impl<'tcx> Clean<Constant> for ty::Const<'tcx> {
1596     fn clean(&self, cx: &mut DocContext<'_>) -> Constant {
1597         // FIXME: instead of storing the stringified expression, store `self` directly instead.
1598         Constant {
1599             type_: self.ty.clean(cx),
1600             kind: ConstantKind::TyConst { expr: self.to_string() },
1601         }
1602     }
1603 }
1604
1605 impl Clean<Item> for hir::FieldDef<'_> {
1606     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1607         let what_rustc_thinks = Item::from_hir_id_and_parts(
1608             self.hir_id,
1609             Some(self.ident.name),
1610             StructFieldItem(self.ty.clean(cx)),
1611             cx,
1612         );
1613         // Don't show `pub` for fields on enum variants; they are always public
1614         Item { visibility: self.vis.clean(cx), ..what_rustc_thinks }
1615     }
1616 }
1617
1618 impl Clean<Item> for ty::FieldDef {
1619     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1620         let what_rustc_thinks = Item::from_def_id_and_parts(
1621             self.did,
1622             Some(self.ident.name),
1623             StructFieldItem(cx.tcx.type_of(self.did).clean(cx)),
1624             cx,
1625         );
1626         // Don't show `pub` for fields on enum variants; they are always public
1627         Item { visibility: self.vis.clean(cx), ..what_rustc_thinks }
1628     }
1629 }
1630
1631 impl Clean<Visibility> for hir::Visibility<'_> {
1632     fn clean(&self, cx: &mut DocContext<'_>) -> Visibility {
1633         match self.node {
1634             hir::VisibilityKind::Public => Visibility::Public,
1635             hir::VisibilityKind::Inherited => Visibility::Inherited,
1636             hir::VisibilityKind::Crate(_) => {
1637                 let krate = DefId::local(CRATE_DEF_INDEX);
1638                 Visibility::Restricted(krate)
1639             }
1640             hir::VisibilityKind::Restricted { ref path, .. } => {
1641                 let path = path.clean(cx);
1642                 let did = register_res(cx, path.res);
1643                 Visibility::Restricted(did)
1644             }
1645         }
1646     }
1647 }
1648
1649 impl Clean<Visibility> for ty::Visibility {
1650     fn clean(&self, _cx: &mut DocContext<'_>) -> Visibility {
1651         match *self {
1652             ty::Visibility::Public => Visibility::Public,
1653             // NOTE: this is not quite right: `ty` uses `Invisible` to mean 'private',
1654             // while rustdoc really does mean inherited. That means that for enum variants, such as
1655             // `pub enum E { V }`, `V` will be marked as `Public` by `ty`, but as `Inherited` by rustdoc.
1656             // This is the main reason `impl Clean for hir::Visibility` still exists; various parts of clean
1657             // override `tcx.visibility` explicitly to make sure this distinction is captured.
1658             ty::Visibility::Invisible => Visibility::Inherited,
1659             ty::Visibility::Restricted(module) => Visibility::Restricted(module),
1660         }
1661     }
1662 }
1663
1664 impl Clean<VariantStruct> for rustc_hir::VariantData<'_> {
1665     fn clean(&self, cx: &mut DocContext<'_>) -> VariantStruct {
1666         VariantStruct {
1667             struct_type: CtorKind::from_hir(self),
1668             fields: self.fields().iter().map(|x| x.clean(cx)).collect(),
1669             fields_stripped: false,
1670         }
1671     }
1672 }
1673
1674 impl Clean<Vec<Item>> for hir::VariantData<'_> {
1675     fn clean(&self, cx: &mut DocContext<'_>) -> Vec<Item> {
1676         self.fields().iter().map(|x| x.clean(cx)).collect()
1677     }
1678 }
1679
1680 impl Clean<Item> for ty::VariantDef {
1681     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1682         let kind = match self.ctor_kind {
1683             CtorKind::Const => Variant::CLike,
1684             CtorKind::Fn => Variant::Tuple(
1685                 self.fields
1686                     .iter()
1687                     .map(|field| {
1688                         let name = Some(field.ident.name);
1689                         let kind = StructFieldItem(cx.tcx.type_of(field.did).clean(cx));
1690                         let what_rustc_thinks =
1691                             Item::from_def_id_and_parts(field.did, name, kind, cx);
1692                         // don't show `pub` for fields, which are always public
1693                         Item { visibility: Visibility::Inherited, ..what_rustc_thinks }
1694                     })
1695                     .collect(),
1696             ),
1697             CtorKind::Fictive => Variant::Struct(VariantStruct {
1698                 struct_type: CtorKind::Fictive,
1699                 fields_stripped: false,
1700                 fields: self
1701                     .fields
1702                     .iter()
1703                     .map(|field| {
1704                         let name = Some(field.ident.name);
1705                         let kind = StructFieldItem(cx.tcx.type_of(field.did).clean(cx));
1706                         let what_rustc_thinks =
1707                             Item::from_def_id_and_parts(field.did, name, kind, cx);
1708                         // don't show `pub` for fields, which are always public
1709                         Item { visibility: Visibility::Inherited, ..what_rustc_thinks }
1710                     })
1711                     .collect(),
1712             }),
1713         };
1714         let what_rustc_thinks =
1715             Item::from_def_id_and_parts(self.def_id, Some(self.ident.name), VariantItem(kind), cx);
1716         // don't show `pub` for fields, which are always public
1717         Item { visibility: Inherited, ..what_rustc_thinks }
1718     }
1719 }
1720
1721 impl Clean<Variant> for hir::VariantData<'_> {
1722     fn clean(&self, cx: &mut DocContext<'_>) -> Variant {
1723         match self {
1724             hir::VariantData::Struct(..) => Variant::Struct(self.clean(cx)),
1725             hir::VariantData::Tuple(..) => Variant::Tuple(self.clean(cx)),
1726             hir::VariantData::Unit(..) => Variant::CLike,
1727         }
1728     }
1729 }
1730
1731 impl Clean<Path> for hir::Path<'_> {
1732     fn clean(&self, cx: &mut DocContext<'_>) -> Path {
1733         Path { res: self.res, segments: self.segments.clean(cx) }
1734     }
1735 }
1736
1737 impl Clean<GenericArgs> for hir::GenericArgs<'_> {
1738     fn clean(&self, cx: &mut DocContext<'_>) -> GenericArgs {
1739         if self.parenthesized {
1740             let output = self.bindings[0].ty().clean(cx);
1741             let output =
1742                 if output != Type::Tuple(Vec::new()) { Some(Box::new(output)) } else { None };
1743             GenericArgs::Parenthesized { inputs: self.inputs().clean(cx), output }
1744         } else {
1745             GenericArgs::AngleBracketed {
1746                 args: self
1747                     .args
1748                     .iter()
1749                     .map(|arg| match arg {
1750                         hir::GenericArg::Lifetime(lt) if !lt.is_elided() => {
1751                             GenericArg::Lifetime(lt.clean(cx))
1752                         }
1753                         hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
1754                         hir::GenericArg::Type(ty) => GenericArg::Type(ty.clean(cx)),
1755                         hir::GenericArg::Const(ct) => GenericArg::Const(Box::new(ct.clean(cx))),
1756                         hir::GenericArg::Infer(_inf) => GenericArg::Infer,
1757                     })
1758                     .collect(),
1759                 bindings: self.bindings.clean(cx),
1760             }
1761         }
1762     }
1763 }
1764
1765 impl Clean<PathSegment> for hir::PathSegment<'_> {
1766     fn clean(&self, cx: &mut DocContext<'_>) -> PathSegment {
1767         PathSegment { name: self.ident.name, args: self.args().clean(cx) }
1768     }
1769 }
1770
1771 impl Clean<BareFunctionDecl> for hir::BareFnTy<'_> {
1772     fn clean(&self, cx: &mut DocContext<'_>) -> BareFunctionDecl {
1773         let (generic_params, decl) = enter_impl_trait(cx, |cx| {
1774             (self.generic_params.clean(cx), (&*self.decl, self.param_names).clean(cx))
1775         });
1776         BareFunctionDecl { unsafety: self.unsafety, abi: self.abi, decl, generic_params }
1777     }
1778 }
1779
1780 impl Clean<Vec<Item>> for (&hir::Item<'_>, Option<Symbol>) {
1781     fn clean(&self, cx: &mut DocContext<'_>) -> Vec<Item> {
1782         use hir::ItemKind;
1783
1784         let (item, renamed) = self;
1785         let def_id = item.def_id.to_def_id();
1786         let mut name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
1787         cx.with_param_env(def_id, |cx| {
1788             let kind = match item.kind {
1789                 ItemKind::Static(ty, mutability, body_id) => {
1790                     StaticItem(Static { type_: ty.clean(cx), mutability, expr: Some(body_id) })
1791                 }
1792                 ItemKind::Const(ty, body_id) => ConstantItem(Constant {
1793                     type_: ty.clean(cx),
1794                     kind: ConstantKind::Local { body: body_id, def_id },
1795                 }),
1796                 ItemKind::OpaqueTy(ref ty) => OpaqueTyItem(OpaqueTy {
1797                     bounds: ty.bounds.clean(cx),
1798                     generics: ty.generics.clean(cx),
1799                 }),
1800                 ItemKind::TyAlias(hir_ty, ref generics) => {
1801                     let rustdoc_ty = hir_ty.clean(cx);
1802                     let ty = hir_ty_to_ty(cx.tcx, hir_ty).clean(cx);
1803                     TypedefItem(
1804                         Typedef {
1805                             type_: rustdoc_ty,
1806                             generics: generics.clean(cx),
1807                             item_type: Some(ty),
1808                         },
1809                         false,
1810                     )
1811                 }
1812                 ItemKind::Enum(ref def, ref generics) => EnumItem(Enum {
1813                     variants: def.variants.iter().map(|v| v.clean(cx)).collect(),
1814                     generics: generics.clean(cx),
1815                     variants_stripped: false,
1816                 }),
1817                 ItemKind::TraitAlias(ref generics, bounds) => TraitAliasItem(TraitAlias {
1818                     generics: generics.clean(cx),
1819                     bounds: bounds.clean(cx),
1820                 }),
1821                 ItemKind::Union(ref variant_data, ref generics) => UnionItem(Union {
1822                     generics: generics.clean(cx),
1823                     fields: variant_data.fields().clean(cx),
1824                     fields_stripped: false,
1825                 }),
1826                 ItemKind::Struct(ref variant_data, ref generics) => StructItem(Struct {
1827                     struct_type: CtorKind::from_hir(variant_data),
1828                     generics: generics.clean(cx),
1829                     fields: variant_data.fields().clean(cx),
1830                     fields_stripped: false,
1831                 }),
1832                 ItemKind::Impl(ref impl_) => return clean_impl(impl_, item.hir_id(), cx),
1833                 // proc macros can have a name set by attributes
1834                 ItemKind::Fn(ref sig, ref generics, body_id) => {
1835                     clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
1836                 }
1837                 ItemKind::Macro(ref macro_def) => MacroItem(Macro {
1838                     source: display_macro_source(cx, name, &macro_def, def_id, &item.vis),
1839                 }),
1840                 ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref item_ids) => {
1841                     let items = item_ids
1842                         .iter()
1843                         .map(|ti| cx.tcx.hir().trait_item(ti.id).clean(cx))
1844                         .collect();
1845                     TraitItem(Trait {
1846                         unsafety,
1847                         items,
1848                         generics: generics.clean(cx),
1849                         bounds: bounds.clean(cx),
1850                         is_auto: is_auto.clean(cx),
1851                     })
1852                 }
1853                 ItemKind::ExternCrate(orig_name) => {
1854                     return clean_extern_crate(item, name, orig_name, cx);
1855                 }
1856                 ItemKind::Use(path, kind) => {
1857                     return clean_use_statement(item, name, path, kind, cx);
1858                 }
1859                 _ => unreachable!("not yet converted"),
1860             };
1861
1862             vec![Item::from_def_id_and_parts(def_id, Some(name), kind, cx)]
1863         })
1864     }
1865 }
1866
1867 impl Clean<Item> for hir::Variant<'_> {
1868     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1869         let kind = VariantItem(self.data.clean(cx));
1870         let what_rustc_thinks =
1871             Item::from_hir_id_and_parts(self.id, Some(self.ident.name), kind, cx);
1872         // don't show `pub` for variants, which are always public
1873         Item { visibility: Inherited, ..what_rustc_thinks }
1874     }
1875 }
1876
1877 impl Clean<bool> for ty::ImplPolarity {
1878     /// Returns whether the impl has negative polarity.
1879     fn clean(&self, _: &mut DocContext<'_>) -> bool {
1880         match self {
1881             &ty::ImplPolarity::Positive |
1882             // FIXME: do we want to do something else here?
1883             &ty::ImplPolarity::Reservation => false,
1884             &ty::ImplPolarity::Negative => true,
1885         }
1886     }
1887 }
1888
1889 fn clean_impl(impl_: &hir::Impl<'_>, hir_id: hir::HirId, cx: &mut DocContext<'_>) -> Vec<Item> {
1890     let tcx = cx.tcx;
1891     let mut ret = Vec::new();
1892     let trait_ = impl_.of_trait.clean(cx);
1893     let items =
1894         impl_.items.iter().map(|ii| tcx.hir().impl_item(ii.id).clean(cx)).collect::<Vec<_>>();
1895     let def_id = tcx.hir().local_def_id(hir_id);
1896
1897     // If this impl block is an implementation of the Deref trait, then we
1898     // need to try inlining the target's inherent impl blocks as well.
1899     if trait_.def_id() == tcx.lang_items().deref_trait() {
1900         build_deref_target_impls(cx, &items, &mut ret);
1901     }
1902
1903     let for_ = impl_.self_ty.clean(cx);
1904     let type_alias = for_.def_id().and_then(|did| match tcx.def_kind(did) {
1905         DefKind::TyAlias => Some(tcx.type_of(did).clean(cx)),
1906         _ => None,
1907     });
1908     let mut make_item = |trait_: Option<Path>, for_: Type, items: Vec<Item>| {
1909         let kind = ImplItem(Impl {
1910             span: types::rustc_span(tcx.hir().local_def_id(hir_id).to_def_id(), tcx),
1911             unsafety: impl_.unsafety,
1912             generics: impl_.generics.clean(cx),
1913             trait_,
1914             for_,
1915             items,
1916             negative_polarity: tcx.impl_polarity(def_id).clean(cx),
1917             synthetic: false,
1918             blanket_impl: None,
1919         });
1920         Item::from_hir_id_and_parts(hir_id, None, kind, cx)
1921     };
1922     if let Some(type_alias) = type_alias {
1923         ret.push(make_item(trait_.clone(), type_alias, items.clone()));
1924     }
1925     ret.push(make_item(trait_, for_, items));
1926     ret
1927 }
1928
1929 fn clean_extern_crate(
1930     krate: &hir::Item<'_>,
1931     name: Symbol,
1932     orig_name: Option<Symbol>,
1933     cx: &mut DocContext<'_>,
1934 ) -> Vec<Item> {
1935     // this is the ID of the `extern crate` statement
1936     let cnum = cx.tcx.extern_mod_stmt_cnum(krate.def_id).unwrap_or(LOCAL_CRATE);
1937     // this is the ID of the crate itself
1938     let crate_def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
1939     let attrs = cx.tcx.hir().attrs(krate.hir_id());
1940     let please_inline = krate.vis.node.is_pub()
1941         && attrs.iter().any(|a| {
1942             a.has_name(sym::doc)
1943                 && match a.meta_item_list() {
1944                     Some(l) => attr::list_contains_name(&l, sym::inline),
1945                     None => false,
1946                 }
1947         });
1948
1949     if please_inline {
1950         let mut visited = FxHashSet::default();
1951
1952         let res = Res::Def(DefKind::Mod, crate_def_id);
1953
1954         if let Some(items) = inline::try_inline(
1955             cx,
1956             cx.tcx.parent_module(krate.hir_id()).to_def_id(),
1957             Some(krate.def_id.to_def_id()),
1958             res,
1959             name,
1960             Some(attrs),
1961             &mut visited,
1962         ) {
1963             return items;
1964         }
1965     }
1966
1967     // FIXME: using `from_def_id_and_kind` breaks `rustdoc/masked` for some reason
1968     vec![Item {
1969         name: Some(name),
1970         attrs: box attrs.clean(cx),
1971         def_id: crate_def_id.into(),
1972         visibility: krate.vis.clean(cx),
1973         kind: box ExternCrateItem { src: orig_name },
1974         cfg: attrs.cfg(cx.sess()),
1975     }]
1976 }
1977
1978 fn clean_use_statement(
1979     import: &hir::Item<'_>,
1980     name: Symbol,
1981     path: &hir::Path<'_>,
1982     kind: hir::UseKind,
1983     cx: &mut DocContext<'_>,
1984 ) -> Vec<Item> {
1985     // We need this comparison because some imports (for std types for example)
1986     // are "inserted" as well but directly by the compiler and they should not be
1987     // taken into account.
1988     if import.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
1989         return Vec::new();
1990     }
1991
1992     let attrs = cx.tcx.hir().attrs(import.hir_id());
1993     let inline_attr = attrs.lists(sym::doc).get_word_attr(sym::inline);
1994     let pub_underscore = import.vis.node.is_pub() && name == kw::Underscore;
1995
1996     if pub_underscore {
1997         if let Some(ref inline) = inline_attr {
1998             rustc_errors::struct_span_err!(
1999                 cx.tcx.sess,
2000                 inline.span(),
2001                 E0780,
2002                 "anonymous imports cannot be inlined"
2003             )
2004             .span_label(import.span, "anonymous import")
2005             .emit();
2006         }
2007     }
2008
2009     // We consider inlining the documentation of `pub use` statements, but we
2010     // forcefully don't inline if this is not public or if the
2011     // #[doc(no_inline)] attribute is present.
2012     // Don't inline doc(hidden) imports so they can be stripped at a later stage.
2013     let mut denied = !(import.vis.node.is_pub()
2014         || (cx.render_options.document_private && import.vis.node.is_pub_restricted()))
2015         || pub_underscore
2016         || attrs.iter().any(|a| {
2017             a.has_name(sym::doc)
2018                 && match a.meta_item_list() {
2019                     Some(l) => {
2020                         attr::list_contains_name(&l, sym::no_inline)
2021                             || attr::list_contains_name(&l, sym::hidden)
2022                     }
2023                     None => false,
2024                 }
2025         });
2026
2027     // Also check whether imports were asked to be inlined, in case we're trying to re-export a
2028     // crate in Rust 2018+
2029     let path = path.clean(cx);
2030     let inner = if kind == hir::UseKind::Glob {
2031         if !denied {
2032             let mut visited = FxHashSet::default();
2033             if let Some(items) = inline::try_inline_glob(cx, path.res, &mut visited) {
2034                 return items;
2035             }
2036         }
2037         Import::new_glob(resolve_use_source(cx, path), true)
2038     } else {
2039         if inline_attr.is_none() {
2040             if let Res::Def(DefKind::Mod, did) = path.res {
2041                 if !did.is_local() && did.index == CRATE_DEF_INDEX {
2042                     // if we're `pub use`ing an extern crate root, don't inline it unless we
2043                     // were specifically asked for it
2044                     denied = true;
2045                 }
2046             }
2047         }
2048         if !denied {
2049             let mut visited = FxHashSet::default();
2050             let import_def_id = import.def_id.to_def_id();
2051
2052             if let Some(mut items) = inline::try_inline(
2053                 cx,
2054                 cx.tcx.parent_module(import.hir_id()).to_def_id(),
2055                 Some(import_def_id),
2056                 path.res,
2057                 name,
2058                 Some(attrs),
2059                 &mut visited,
2060             ) {
2061                 items.push(Item::from_def_id_and_parts(
2062                     import_def_id,
2063                     None,
2064                     ImportItem(Import::new_simple(name, resolve_use_source(cx, path), false)),
2065                     cx,
2066                 ));
2067                 return items;
2068             }
2069         }
2070         Import::new_simple(name, resolve_use_source(cx, path), true)
2071     };
2072
2073     vec![Item::from_def_id_and_parts(import.def_id.to_def_id(), None, ImportItem(inner), cx)]
2074 }
2075
2076 impl Clean<Item> for (&hir::ForeignItem<'_>, Option<Symbol>) {
2077     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
2078         let (item, renamed) = self;
2079         cx.with_param_env(item.def_id.to_def_id(), |cx| {
2080             let kind = match item.kind {
2081                 hir::ForeignItemKind::Fn(ref decl, ref names, ref generics) => {
2082                     let abi = cx.tcx.hir().get_foreign_abi(item.hir_id());
2083                     let (generics, decl) = enter_impl_trait(cx, |cx| {
2084                         (generics.clean(cx), (&**decl, &names[..]).clean(cx))
2085                     });
2086                     ForeignFunctionItem(Function {
2087                         decl,
2088                         generics,
2089                         header: hir::FnHeader {
2090                             unsafety: if abi == Abi::RustIntrinsic {
2091                                 intrinsic_operation_unsafety(item.ident.name)
2092                             } else {
2093                                 hir::Unsafety::Unsafe
2094                             },
2095                             abi,
2096                             constness: hir::Constness::NotConst,
2097                             asyncness: hir::IsAsync::NotAsync,
2098                         },
2099                     })
2100                 }
2101                 hir::ForeignItemKind::Static(ref ty, mutability) => {
2102                     ForeignStaticItem(Static { type_: ty.clean(cx), mutability, expr: None })
2103                 }
2104                 hir::ForeignItemKind::Type => ForeignTypeItem,
2105             };
2106
2107             Item::from_hir_id_and_parts(
2108                 item.hir_id(),
2109                 Some(renamed.unwrap_or(item.ident.name)),
2110                 kind,
2111                 cx,
2112             )
2113         })
2114     }
2115 }
2116
2117 impl Clean<TypeBinding> for hir::TypeBinding<'_> {
2118     fn clean(&self, cx: &mut DocContext<'_>) -> TypeBinding {
2119         TypeBinding { name: self.ident.name, kind: self.kind.clean(cx) }
2120     }
2121 }
2122
2123 impl Clean<TypeBindingKind> for hir::TypeBindingKind<'_> {
2124     fn clean(&self, cx: &mut DocContext<'_>) -> TypeBindingKind {
2125         match *self {
2126             hir::TypeBindingKind::Equality { ref ty } => {
2127                 TypeBindingKind::Equality { ty: ty.clean(cx) }
2128             }
2129             hir::TypeBindingKind::Constraint { ref bounds } => {
2130                 TypeBindingKind::Constraint { bounds: bounds.iter().map(|b| b.clean(cx)).collect() }
2131             }
2132         }
2133     }
2134 }