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