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);
 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<Type> for (ty::TraitRef<'_>, &[TypeBinding]) {
 156     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
 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         ResolvedPath { path, did: trait_ref.def_id, is_generic: false }
 172     }
 173 }
 174
 175 impl<'tcx> Clean<GenericBound> for ty::TraitRef<'tcx> {
 176     fn clean(&self, cx: &mut DocContext<'_>) -> GenericBound {
 177         GenericBound::TraitBound(
 178             PolyTrait { trait_: (*self, &[][..]).clean(cx), generic_params: vec![] },
 179             hir::TraitBoundModifier::None,
 180         )
 181     }
 182 }
 183
 184 impl Clean<GenericBound> for (ty::PolyTraitRef<'_>, &[TypeBinding]) {
 185     fn clean(&self, cx: &mut DocContext<'_>) -> GenericBound {
 186         let (poly_trait_ref, bounds) = *self;
 187         let poly_trait_ref = poly_trait_ref.lift_to_tcx(cx.tcx).unwrap();
 188
 189         // collect any late bound regions
 190         let late_bound_regions: Vec<_> = cx
 191             .tcx
 192             .collect_referenced_late_bound_regions(&poly_trait_ref)
 193             .into_iter()
 194             .filter_map(|br| match br {
 195                 ty::BrNamed(_, name) => Some(GenericParamDef {
 196                     name,
 197                     kind: GenericParamDefKind::Lifetime { outlives: vec![] },
 198                 }),
 199                 _ => None,
 200             })
 201             .collect();
 202
 203         GenericBound::TraitBound(
 204             PolyTrait {
 205                 trait_: (poly_trait_ref.skip_binder(), bounds).clean(cx),
 206                 generic_params: late_bound_regions,
 207             },
 208             hir::TraitBoundModifier::None,
 209         )
 210     }
 211 }
 212
 213 impl<'tcx> Clean<GenericBound> for ty::PolyTraitRef<'tcx> {
 214     fn clean(&self, cx: &mut DocContext<'_>) -> GenericBound {
 215         (*self, &[][..]).clean(cx)
 216     }
 217 }
 218
 219 impl Clean<Lifetime> for hir::Lifetime {
 220     fn clean(&self, cx: &mut DocContext<'_>) -> Lifetime {
 221         let def = cx.tcx.named_region(self.hir_id);
 222         match def {
 223             Some(
 224                 rl::Region::EarlyBound(_, node_id, _)
 225                 | rl::Region::LateBound(_, _, node_id, _)
 226                 | rl::Region::Free(_, node_id),
 227             ) => {
 228                 if let Some(lt) = cx.lt_substs.get(&node_id).cloned() {
 229                     return lt;
 230                 }
 231             }
 232             _ => {}
 233         }
 234         Lifetime(self.name.ident().name)
 235     }
 236 }
 237
 238 impl Clean<Constant> for hir::ConstArg {
 239     fn clean(&self, cx: &mut DocContext<'_>) -> Constant {
 240         Constant {
 241             type_: cx
 242                 .tcx
 243                 .type_of(cx.tcx.hir().body_owner_def_id(self.value.body).to_def_id())
 244                 .clean(cx),
 245             kind: ConstantKind::Anonymous { body: self.value.body },
 246         }
 247     }
 248 }
 249
 250 impl Clean<Option<Lifetime>> for ty::RegionKind {
 251     fn clean(&self, _cx: &mut DocContext<'_>) -> Option<Lifetime> {
 252         match *self {
 253             ty::ReStatic => Some(Lifetime::statik()),
 254             ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => {
 255                 Some(Lifetime(name))
 256             }
 257             ty::ReEarlyBound(ref data) => Some(Lifetime(data.name)),
 258
 259             ty::ReLateBound(..)
 260             | ty::ReFree(..)
 261             | ty::ReVar(..)
 262             | ty::RePlaceholder(..)
 263             | ty::ReEmpty(_)
 264             | ty::ReErased => {
 265                 debug!("cannot clean region {:?}", self);
 266                 None
 267             }
 268         }
 269     }
 270 }
 271
 272 impl Clean<WherePredicate> for hir::WherePredicate<'_> {
 273     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
 274         match *self {
 275             hir::WherePredicate::BoundPredicate(ref wbp) => {
 276                 let bound_params = wbp
 277                     .bound_generic_params
 278                     .into_iter()
 279                     .map(|param| {
 280                         // Higher-ranked params must be lifetimes.
 281                         // Higher-ranked lifetimes can't have bounds.
 282                         assert_matches!(
 283                             param,
 284                             hir::GenericParam {
 285                                 kind: hir::GenericParamKind::Lifetime { .. },
 286                                 bounds: [],
 287                                 ..
 288                             }
 289                         );
 290                         Lifetime(param.name.ident().name)
 291                     })
 292                     .collect();
 293                 WherePredicate::BoundPredicate {
 294                     ty: wbp.bounded_ty.clean(cx),
 295                     bounds: wbp.bounds.clean(cx),
 296                     bound_params,
 297                 }
 298             }
 299
 300             hir::WherePredicate::RegionPredicate(ref wrp) => WherePredicate::RegionPredicate {
 301                 lifetime: wrp.lifetime.clean(cx),
 302                 bounds: wrp.bounds.clean(cx),
 303             },
 304
 305             hir::WherePredicate::EqPredicate(ref wrp) => {
 306                 WherePredicate::EqPredicate { lhs: wrp.lhs_ty.clean(cx), rhs: wrp.rhs_ty.clean(cx) }
 307             }
 308         }
 309     }
 310 }
 311
 312 impl<'a> Clean<Option<WherePredicate>> for ty::Predicate<'a> {
 313     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 314         let bound_predicate = self.kind();
 315         match bound_predicate.skip_binder() {
 316             ty::PredicateKind::Trait(pred) => Some(bound_predicate.rebind(pred).clean(cx)),
 317             ty::PredicateKind::RegionOutlives(pred) => pred.clean(cx),
 318             ty::PredicateKind::TypeOutlives(pred) => pred.clean(cx),
 319             ty::PredicateKind::Projection(pred) => Some(pred.clean(cx)),
 320             ty::PredicateKind::ConstEvaluatable(..) => None,
 321
 322             ty::PredicateKind::Subtype(..)
 323             | ty::PredicateKind::Coerce(..)
 324             | ty::PredicateKind::WellFormed(..)
 325             | ty::PredicateKind::ObjectSafe(..)
 326             | ty::PredicateKind::ClosureKind(..)
 327             | ty::PredicateKind::ConstEquate(..)
 328             | ty::PredicateKind::TypeWellFormedFromEnv(..) => panic!("not user writable"),
 329         }
 330     }
 331 }
 332
 333 impl<'a> Clean<WherePredicate> for ty::PolyTraitPredicate<'a> {
 334     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
 335         let poly_trait_ref = self.map_bound(|pred| pred.trait_ref);
 336         WherePredicate::BoundPredicate {
 337             ty: poly_trait_ref.skip_binder().self_ty().clean(cx),
 338             bounds: vec![poly_trait_ref.clean(cx)],
 339             bound_params: Vec::new(),
 340         }
 341     }
 342 }
 343
 344 impl<'tcx> Clean<Option<WherePredicate>>
 345     for ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
 346 {
 347     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 348         let ty::OutlivesPredicate(a, b) = self;
 349
 350         if let (ty::ReEmpty(_), ty::ReEmpty(_)) = (a, b) {
 351             return None;
 352         }
 353
 354         Some(WherePredicate::RegionPredicate {
 355             lifetime: a.clean(cx).expect("failed to clean lifetime"),
 356             bounds: vec![GenericBound::Outlives(b.clean(cx).expect("failed to clean bounds"))],
 357         })
 358     }
 359 }
 360
 361 impl<'tcx> Clean<Option<WherePredicate>> for ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>> {
 362     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 363         let ty::OutlivesPredicate(ty, lt) = self;
 364
 365         if let ty::ReEmpty(_) = lt {
 366             return None;
 367         }
 368
 369         Some(WherePredicate::BoundPredicate {
 370             ty: ty.clean(cx),
 371             bounds: vec![GenericBound::Outlives(lt.clean(cx).expect("failed to clean lifetimes"))],
 372             bound_params: Vec::new(),
 373         })
 374     }
 375 }
 376
 377 impl<'tcx> Clean<WherePredicate> for ty::ProjectionPredicate<'tcx> {
 378     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
 379         let ty::ProjectionPredicate { projection_ty, ty } = self;
 380         WherePredicate::EqPredicate { lhs: projection_ty.clean(cx), rhs: ty.clean(cx) }
 381     }
 382 }
 383
 384 impl<'tcx> Clean<Type> for ty::ProjectionTy<'tcx> {
 385     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
 386         let lifted = self.lift_to_tcx(cx.tcx).unwrap();
 387         let trait_ = match lifted.trait_ref(cx.tcx).clean(cx) {
 388             GenericBound::TraitBound(t, _) => t.trait_,
 389             GenericBound::Outlives(_) => panic!("cleaning a trait got a lifetime"),
 390         };
 391         let self_type = self.self_ty().clean(cx);
 392         Type::QPath {
 393             name: cx.tcx.associated_item(self.item_def_id).ident.name,
 394             self_def_id: self_type.def_id(),
 395             self_type: Box::new(self_type),
 396             trait_: Box::new(trait_),
 397         }
 398     }
 399 }
 400
 401 impl Clean<GenericParamDef> for ty::GenericParamDef {
 402     fn clean(&self, cx: &mut DocContext<'_>) -> GenericParamDef {
 403         let (name, kind) = match self.kind {
 404             ty::GenericParamDefKind::Lifetime => {
 405                 (self.name, GenericParamDefKind::Lifetime { outlives: vec![] })
 406             }
 407             ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
 408                 let default = if has_default {
 409                     let mut default = cx.tcx.type_of(self.def_id).clean(cx);
 410
 411                     // We need to reassign the `self_def_id`, if there's a parent (which is the
 412                     // `Self` type), so we can properly render `<Self as X>` casts, because the
 413                     // information about which type `Self` is, is only present here, but not in
 414                     // the cleaning process of the type itself. To resolve this and have the
 415                     // `self_def_id` set, we override it here.
 416                     // See https://github.com/rust-lang/rust/issues/85454
 417                     if let QPath { ref mut self_def_id, .. } = default {
 418                         *self_def_id = cx.tcx.parent(self.def_id);
 419                     }
 420
 421                     Some(default)
 422                 } else {
 423                     None
 424                 };
 425                 (
 426                     self.name,
 427                     GenericParamDefKind::Type {
 428                         did: self.def_id,
 429                         bounds: vec![], // These are filled in from the where-clauses.
 430                         default,
 431                         synthetic,
 432                     },
 433                 )
 434             }
 435             ty::GenericParamDefKind::Const { has_default, .. } => (
 436                 self.name,
 437                 GenericParamDefKind::Const {
 438                     did: self.def_id,
 439                     ty: cx.tcx.type_of(self.def_id).clean(cx),
 440                     default: match has_default {
 441                         true => Some(cx.tcx.const_param_default(self.def_id).to_string()),
 442                         false => None,
 443                     },
 444                 },
 445             ),
 446         };
 447
 448         GenericParamDef { name, kind }
 449     }
 450 }
 451
 452 impl Clean<GenericParamDef> for hir::GenericParam<'_> {
 453     fn clean(&self, cx: &mut DocContext<'_>) -> GenericParamDef {
 454         let (name, kind) = match self.kind {
 455             hir::GenericParamKind::Lifetime { .. } => {
 456                 let outlives = self
 457                     .bounds
 458                     .iter()
 459                     .map(|bound| match bound {
 460                         hir::GenericBound::Outlives(lt) => lt.clean(cx),
 461                         _ => panic!(),
 462                     })
 463                     .collect();
 464                 (self.name.ident().name, GenericParamDefKind::Lifetime { outlives })
 465             }
 466             hir::GenericParamKind::Type { ref default, synthetic } => (
 467                 self.name.ident().name,
 468                 GenericParamDefKind::Type {
 469                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
 470                     bounds: self.bounds.clean(cx),
 471                     default: default.clean(cx),
 472                     synthetic,
 473                 },
 474             ),
 475             hir::GenericParamKind::Const { ref ty, default } => (
 476                 self.name.ident().name,
 477                 GenericParamDefKind::Const {
 478                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
 479                     ty: ty.clean(cx),
 480                     default: default.map(|ct| {
 481                         let def_id = cx.tcx.hir().local_def_id(ct.hir_id);
 482                         ty::Const::from_anon_const(cx.tcx, def_id).to_string()
 483                     }),
 484                 },
 485             ),
 486         };
 487
 488         GenericParamDef { name, kind }
 489     }
 490 }
 491
 492 impl Clean<Generics> for hir::Generics<'_> {
 493     fn clean(&self, cx: &mut DocContext<'_>) -> Generics {
 494         // Synthetic type-parameters are inserted after normal ones.
 495         // In order for normal parameters to be able to refer to synthetic ones,
 496         // scans them first.
 497         fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
 498             match param.kind {
 499                 hir::GenericParamKind::Type { synthetic, .. } => {
 500                     synthetic == Some(hir::SyntheticTyParamKind::ImplTrait)
 501                 }
 502                 _ => false,
 503             }
 504         }
 505         /// This can happen for `async fn`, e.g. `async fn f<'_>(&'_ self)`.
 506         ///
 507         /// See [`lifetime_to_generic_param`] in [`rustc_ast_lowering`] for more information.
 508         ///
 509         /// [`lifetime_to_generic_param`]: rustc_ast_lowering::LoweringContext::lifetime_to_generic_param
 510         fn is_elided_lifetime(param: &hir::GenericParam<'_>) -> bool {
 511             matches!(
 512                 param.kind,
 513                 hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided }
 514             )
 515         }
 516
 517         let impl_trait_params = self
 518             .params
 519             .iter()
 520             .filter(|param| is_impl_trait(param))
 521             .map(|param| {
 522                 let param: GenericParamDef = param.clean(cx);
 523                 match param.kind {
 524                     GenericParamDefKind::Lifetime { .. } => unreachable!(),
 525                     GenericParamDefKind::Type { did, ref bounds, .. } => {
 526                         cx.impl_trait_bounds.insert(did.into(), bounds.clone());
 527                     }
 528                     GenericParamDefKind::Const { .. } => unreachable!(),
 529                 }
 530                 param
 531             })
 532             .collect::<Vec<_>>();
 533
 534         let mut params = Vec::with_capacity(self.params.len());
 535         for p in self.params.iter().filter(|p| !is_impl_trait(p) && !is_elided_lifetime(p)) {
 536             let p = p.clean(cx);
 537             params.push(p);
 538         }
 539         params.extend(impl_trait_params);
 540
 541         let mut generics =
 542             Generics { params, where_predicates: self.where_clause.predicates.clean(cx) };
 543
 544         // Some duplicates are generated for ?Sized bounds between type params and where
 545         // predicates. The point in here is to move the bounds definitions from type params
 546         // to where predicates when such cases occur.
 547         for where_pred in &mut generics.where_predicates {
 548             match *where_pred {
 549                 WherePredicate::BoundPredicate {
 550                     ty: Generic(ref name), ref mut bounds, ..
 551                 } => {
 552                     if bounds.is_empty() {
 553                         for param in &mut generics.params {
 554                             match param.kind {
 555                                 GenericParamDefKind::Lifetime { .. } => {}
 556                                 GenericParamDefKind::Type { bounds: ref mut ty_bounds, .. } => {
 557                                     if &param.name == name {
 558                                         mem::swap(bounds, ty_bounds);
 559                                         break;
 560                                     }
 561                                 }
 562                                 GenericParamDefKind::Const { .. } => {}
 563                             }
 564                         }
 565                     }
 566                 }
 567                 _ => continue,
 568             }
 569         }
 570         generics
 571     }
 572 }
 573
 574 impl<'a, 'tcx> Clean<Generics> for (&'a ty::Generics, ty::GenericPredicates<'tcx>) {
 575     fn clean(&self, cx: &mut DocContext<'_>) -> Generics {
 576         use self::WherePredicate as WP;
 577         use std::collections::BTreeMap;
 578
 579         let (gens, preds) = *self;
 580
 581         // Don't populate `cx.impl_trait_bounds` before `clean`ning `where` clauses,
 582         // since `Clean for ty::Predicate` would consume them.
 583         let mut impl_trait = BTreeMap::<ImplTraitParam, Vec<GenericBound>>::default();
 584
 585         // Bounds in the type_params and lifetimes fields are repeated in the
 586         // predicates field (see rustc_typeck::collect::ty_generics), so remove
 587         // them.
 588         let stripped_params = gens
 589             .params
 590             .iter()
 591             .filter_map(|param| match param.kind {
 592                 ty::GenericParamDefKind::Lifetime => Some(param.clean(cx)),
 593                 ty::GenericParamDefKind::Type { synthetic, .. } => {
 594                     if param.name == kw::SelfUpper {
 595                         assert_eq!(param.index, 0);
 596                         return None;
 597                     }
 598                     if synthetic == Some(hir::SyntheticTyParamKind::ImplTrait) {
 599                         impl_trait.insert(param.index.into(), vec![]);
 600                         return None;
 601                     }
 602                     Some(param.clean(cx))
 603                 }
 604                 ty::GenericParamDefKind::Const { .. } => Some(param.clean(cx)),
 605             })
 606             .collect::<Vec<GenericParamDef>>();
 607
 608         // param index -> [(DefId of trait, associated type name, type)]
 609         let mut impl_trait_proj = FxHashMap::<u32, Vec<(DefId, Symbol, Ty<'tcx>)>>::default();
 610
 611         let where_predicates = preds
 612             .predicates
 613             .iter()
 614             .flat_map(|(p, _)| {
 615                 let mut projection = None;
 616                 let param_idx = (|| {
 617                     let bound_p = p.kind();
 618                     match bound_p.skip_binder() {
 619                         ty::PredicateKind::Trait(pred) => {
 620                             if let ty::Param(param) = pred.self_ty().kind() {
 621                                 return Some(param.index);
 622                             }
 623                         }
 624                         ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty, _reg)) => {
 625                             if let ty::Param(param) = ty.kind() {
 626                                 return Some(param.index);
 627                             }
 628                         }
 629                         ty::PredicateKind::Projection(p) => {
 630                             if let ty::Param(param) = p.projection_ty.self_ty().kind() {
 631                                 projection = Some(bound_p.rebind(p));
 632                                 return Some(param.index);
 633                             }
 634                         }
 635                         _ => (),
 636                     }
 637
 638                     None
 639                 })();
 640
 641                 if let Some(param_idx) = param_idx {
 642                     if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
 643                         let p = p.clean(cx)?;
 644
 645                         b.extend(
 646                             p.get_bounds()
 647                                 .into_iter()
 648                                 .flatten()
 649                                 .cloned()
 650                                 .filter(|b| !b.is_sized_bound(cx)),
 651                         );
 652
 653                         let proj = projection
 654                             .map(|p| (p.skip_binder().projection_ty.clean(cx), p.skip_binder().ty));
 655                         if let Some(((_, trait_did, name), rhs)) =
 656                             proj.as_ref().and_then(|(lhs, rhs)| Some((lhs.projection()?, rhs)))
 657                         {
 658                             impl_trait_proj
 659                                 .entry(param_idx)
 660                                 .or_default()
 661                                 .push((trait_did, name, rhs));
 662                         }
 663
 664                         return None;
 665                     }
 666                 }
 667
 668                 Some(p)
 669             })
 670             .collect::<Vec<_>>();
 671
 672         for (param, mut bounds) in impl_trait {
 673             // Move trait bounds to the front.
 674             bounds.sort_by_key(|b| !matches!(b, GenericBound::TraitBound(..)));
 675
 676             if let crate::core::ImplTraitParam::ParamIndex(idx) = param {
 677                 if let Some(proj) = impl_trait_proj.remove(&idx) {
 678                     for (trait_did, name, rhs) in proj {
 679                         let rhs = rhs.clean(cx);
 680                         simplify::merge_bounds(cx, &mut bounds, trait_did, name, &rhs);
 681                     }
 682                 }
 683             } else {
 684                 unreachable!();
 685             }
 686
 687             cx.impl_trait_bounds.insert(param, bounds);
 688         }
 689
 690         // Now that `cx.impl_trait_bounds` is populated, we can process
 691         // remaining predicates which could contain `impl Trait`.
 692         let mut where_predicates =
 693             where_predicates.into_iter().flat_map(|p| p.clean(cx)).collect::<Vec<_>>();
 694
 695         // Type parameters have a Sized bound by default unless removed with
 696         // ?Sized. Scan through the predicates and mark any type parameter with
 697         // a Sized bound, removing the bounds as we find them.
 698         //
 699         // Note that associated types also have a sized bound by default, but we
 700         // don't actually know the set of associated types right here so that's
 701         // handled in cleaning associated types
 702         let mut sized_params = FxHashSet::default();
 703         where_predicates.retain(|pred| match *pred {
 704             WP::BoundPredicate { ty: Generic(ref g), ref bounds, .. } => {
 705                 if bounds.iter().any(|b| b.is_sized_bound(cx)) {
 706                     sized_params.insert(*g);
 707                     false
 708                 } else {
 709                     true
 710                 }
 711             }
 712             _ => true,
 713         });
 714
 715         // Run through the type parameters again and insert a ?Sized
 716         // unbound for any we didn't find to be Sized.
 717         for tp in &stripped_params {
 718             if matches!(tp.kind, types::GenericParamDefKind::Type { .. })
 719                 && !sized_params.contains(&tp.name)
 720             {
 721                 where_predicates.push(WP::BoundPredicate {
 722                     ty: Type::Generic(tp.name),
 723                     bounds: vec![GenericBound::maybe_sized(cx)],
 724                     bound_params: Vec::new(),
 725                 })
 726             }
 727         }
 728
 729         // It would be nice to collect all of the bounds on a type and recombine
 730         // them if possible, to avoid e.g., `where T: Foo, T: Bar, T: Sized, T: 'a`
 731         // and instead see `where T: Foo + Bar + Sized + 'a`
 732
 733         Generics {
 734             params: stripped_params,
 735             where_predicates: simplify::where_clauses(cx, where_predicates),
 736         }
 737     }
 738 }
 739
 740 fn clean_fn_or_proc_macro(
 741     item: &hir::Item<'_>,
 742     sig: &'a hir::FnSig<'a>,
 743     generics: &'a hir::Generics<'a>,
 744     body_id: hir::BodyId,
 745     name: &mut Symbol,
 746     cx: &mut DocContext<'_>,
 747 ) -> ItemKind {
 748     let attrs = cx.tcx.hir().attrs(item.hir_id());
 749     let macro_kind = attrs.iter().find_map(|a| {
 750         if a.has_name(sym::proc_macro) {
 751             Some(MacroKind::Bang)
 752         } else if a.has_name(sym::proc_macro_derive) {
 753             Some(MacroKind::Derive)
 754         } else if a.has_name(sym::proc_macro_attribute) {
 755             Some(MacroKind::Attr)
 756         } else {
 757             None
 758         }
 759     });
 760     match macro_kind {
 761         Some(kind) => {
 762             if kind == MacroKind::Derive {
 763                 *name = attrs
 764                     .lists(sym::proc_macro_derive)
 765                     .find_map(|mi| mi.ident())
 766                     .expect("proc-macro derives require a name")
 767                     .name;
 768             }
 769
 770             let mut helpers = Vec::new();
 771             for mi in attrs.lists(sym::proc_macro_derive) {
 772                 if !mi.has_name(sym::attributes) {
 773                     continue;
 774                 }
 775
 776                 if let Some(list) = mi.meta_item_list() {
 777                     for inner_mi in list {
 778                         if let Some(ident) = inner_mi.ident() {
 779                             helpers.push(ident.name);
 780                         }
 781                     }
 782                 }
 783             }
 784             ProcMacroItem(ProcMacro { kind, helpers })
 785         }
 786         None => {
 787             let mut func = (sig, generics, body_id).clean(cx);
 788             let def_id = item.def_id.to_def_id();
 789             func.header.constness =
 790                 if is_const_fn(cx.tcx, def_id) && is_unstable_const_fn(cx.tcx, def_id).is_none() {
 791                     hir::Constness::Const
 792                 } else {
 793                     hir::Constness::NotConst
 794                 };
 795             FunctionItem(func)
 796         }
 797     }
 798 }
 799
 800 impl<'a> Clean<Function> for (&'a hir::FnSig<'a>, &'a hir::Generics<'a>, hir::BodyId) {
 801     fn clean(&self, cx: &mut DocContext<'_>) -> Function {
 802         let (generics, decl) =
 803             enter_impl_trait(cx, |cx| (self.1.clean(cx), (&*self.0.decl, self.2).clean(cx)));
 804         Function { decl, generics, header: self.0.header }
 805     }
 806 }
 807
 808 impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], &'a [Ident]) {
 809     fn clean(&self, cx: &mut DocContext<'_>) -> Arguments {
 810         Arguments {
 811             values: self
 812                 .0
 813                 .iter()
 814                 .enumerate()
 815                 .map(|(i, ty)| {
 816                     let mut name = self.1.get(i).map_or(kw::Empty, |ident| ident.name);
 817                     if name.is_empty() {
 818                         name = kw::Underscore;
 819                     }
 820                     Argument { name, type_: ty.clean(cx) }
 821                 })
 822                 .collect(),
 823         }
 824     }
 825 }
 826
 827 impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], hir::BodyId) {
 828     fn clean(&self, cx: &mut DocContext<'_>) -> Arguments {
 829         let body = cx.tcx.hir().body(self.1);
 830
 831         Arguments {
 832             values: self
 833                 .0
 834                 .iter()
 835                 .enumerate()
 836                 .map(|(i, ty)| Argument {
 837                     name: name_from_pat(&body.params[i].pat),
 838                     type_: ty.clean(cx),
 839                 })
 840                 .collect(),
 841         }
 842     }
 843 }
 844
 845 impl<'a, A: Copy> Clean<FnDecl> for (&'a hir::FnDecl<'a>, A)
 846 where
 847     (&'a [hir::Ty<'a>], A): Clean<Arguments>,
 848 {
 849     fn clean(&self, cx: &mut DocContext<'_>) -> FnDecl {
 850         FnDecl {
 851             inputs: (self.0.inputs, self.1).clean(cx),
 852             output: self.0.output.clean(cx),
 853             c_variadic: self.0.c_variadic,
 854         }
 855     }
 856 }
 857
 858 impl<'tcx> Clean<FnDecl> for (DefId, ty::PolyFnSig<'tcx>) {
 859     fn clean(&self, cx: &mut DocContext<'_>) -> FnDecl {
 860         let (did, sig) = *self;
 861         let mut names = if did.is_local() { &[] } else { cx.tcx.fn_arg_names(did) }.iter();
 862
 863         FnDecl {
 864             output: Return(sig.skip_binder().output().clean(cx)),
 865             c_variadic: sig.skip_binder().c_variadic,
 866             inputs: Arguments {
 867                 values: sig
 868                     .skip_binder()
 869                     .inputs()
 870                     .iter()
 871                     .map(|t| Argument {
 872                         type_: t.clean(cx),
 873                         name: names.next().map_or(kw::Empty, |i| i.name),
 874                     })
 875                     .collect(),
 876             },
 877         }
 878     }
 879 }
 880
 881 impl Clean<FnRetTy> for hir::FnRetTy<'_> {
 882     fn clean(&self, cx: &mut DocContext<'_>) -> FnRetTy {
 883         match *self {
 884             Self::Return(ref typ) => Return(typ.clean(cx)),
 885             Self::DefaultReturn(..) => DefaultReturn,
 886         }
 887     }
 888 }
 889
 890 impl Clean<bool> for hir::IsAuto {
 891     fn clean(&self, _: &mut DocContext<'_>) -> bool {
 892         match *self {
 893             hir::IsAuto::Yes => true,
 894             hir::IsAuto::No => false,
 895         }
 896     }
 897 }
 898
 899 impl Clean<Type> for hir::TraitRef<'_> {
 900     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
 901         let path = self.path.clean(cx);
 902         resolve_type(cx, path)
 903     }
 904 }
 905
 906 impl Clean<PolyTrait> for hir::PolyTraitRef<'_> {
 907     fn clean(&self, cx: &mut DocContext<'_>) -> PolyTrait {
 908         PolyTrait {
 909             trait_: self.trait_ref.clean(cx),
 910             generic_params: self.bound_generic_params.clean(cx),
 911         }
 912     }
 913 }
 914
 915 impl Clean<Item> for hir::TraitItem<'_> {
 916     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
 917         let local_did = self.def_id.to_def_id();
 918         cx.with_param_env(local_did, |cx| {
 919             let inner = match self.kind {
 920                 hir::TraitItemKind::Const(ref ty, default) => {
 921                     AssocConstItem(ty.clean(cx), default.map(|e| print_const_expr(cx.tcx, e)))
 922                 }
 923                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
 924                     let mut m = (sig, &self.generics, body).clean(cx);
 925                     if m.header.constness == hir::Constness::Const
 926                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
 927                     {
 928                         m.header.constness = hir::Constness::NotConst;
 929                     }
 930                     MethodItem(m, None)
 931                 }
 932                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(ref names)) => {
 933                     let (generics, decl) = enter_impl_trait(cx, |cx| {
 934                         (self.generics.clean(cx), (&*sig.decl, &names[..]).clean(cx))
 935                     });
 936                     let mut t = Function { header: sig.header, decl, generics };
 937                     if t.header.constness == hir::Constness::Const
 938                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
 939                     {
 940                         t.header.constness = hir::Constness::NotConst;
 941                     }
 942                     TyMethodItem(t)
 943                 }
 944                 hir::TraitItemKind::Type(ref bounds, ref default) => {
 945                     AssocTypeItem(bounds.clean(cx), default.clean(cx))
 946                 }
 947             };
 948             let what_rustc_thinks =
 949                 Item::from_def_id_and_parts(local_did, Some(self.ident.name), inner, cx);
 950             // Trait items always inherit the trait's visibility -- we don't want to show `pub`.
 951             Item { visibility: Inherited, ..what_rustc_thinks }
 952         })
 953     }
 954 }
 955
 956 impl Clean<Item> for hir::ImplItem<'_> {
 957     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
 958         let local_did = self.def_id.to_def_id();
 959         cx.with_param_env(local_did, |cx| {
 960             let inner = match self.kind {
 961                 hir::ImplItemKind::Const(ref ty, expr) => {
 962                     AssocConstItem(ty.clean(cx), Some(print_const_expr(cx.tcx, expr)))
 963                 }
 964                 hir::ImplItemKind::Fn(ref sig, body) => {
 965                     let mut m = (sig, &self.generics, body).clean(cx);
 966                     if m.header.constness == hir::Constness::Const
 967                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
 968                     {
 969                         m.header.constness = hir::Constness::NotConst;
 970                     }
 971                     MethodItem(m, Some(self.defaultness))
 972                 }
 973                 hir::ImplItemKind::TyAlias(ref hir_ty) => {
 974                     let type_ = hir_ty.clean(cx);
 975                     let item_type = hir_ty_to_ty(cx.tcx, hir_ty).clean(cx);
 976                     TypedefItem(
 977                         Typedef {
 978                             type_,
 979                             generics: Generics::default(),
 980                             item_type: Some(item_type),
 981                         },
 982                         true,
 983                     )
 984                 }
 985             };
 986
 987             let what_rustc_thinks =
 988                 Item::from_def_id_and_parts(local_did, Some(self.ident.name), inner, cx);
 989             let parent_item = cx.tcx.hir().expect_item(cx.tcx.hir().get_parent_item(self.hir_id()));
 990             if let hir::ItemKind::Impl(impl_) = &parent_item.kind {
 991                 if impl_.of_trait.is_some() {
 992                     // Trait impl items always inherit the impl's visibility --
 993                     // we don't want to show `pub`.
 994                     Item { visibility: Inherited, ..what_rustc_thinks }
 995                 } else {
 996                     what_rustc_thinks
 997                 }
 998             } else {
 999                 panic!("found impl item with non-impl parent {:?}", parent_item);
1000             }
1001         })
1002     }
1003 }
1004
1005 impl Clean<Item> for ty::AssocItem {
1006     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1007         let tcx = cx.tcx;
1008         let kind = match self.kind {
1009             ty::AssocKind::Const => {
1010                 let ty = tcx.type_of(self.def_id);
1011                 let default = if self.defaultness.has_value() {
1012                     Some(inline::print_inlined_const(tcx, self.def_id))
1013                 } else {
1014                     None
1015                 };
1016                 AssocConstItem(ty.clean(cx), default)
1017             }
1018             ty::AssocKind::Fn => {
1019                 let generics =
1020                     (tcx.generics_of(self.def_id), tcx.explicit_predicates_of(self.def_id))
1021                         .clean(cx);
1022                 let sig = tcx.fn_sig(self.def_id);
1023                 let mut decl = (self.def_id, sig).clean(cx);
1024
1025                 if self.fn_has_self_parameter {
1026                     let self_ty = match self.container {
1027                         ty::ImplContainer(def_id) => tcx.type_of(def_id),
1028                         ty::TraitContainer(_) => tcx.types.self_param,
1029                     };
1030                     let self_arg_ty = sig.input(0).skip_binder();
1031                     if self_arg_ty == self_ty {
1032                         decl.inputs.values[0].type_ = Generic(kw::SelfUpper);
1033                     } else if let ty::Ref(_, ty, _) = *self_arg_ty.kind() {
1034                         if ty == self_ty {
1035                             match decl.inputs.values[0].type_ {
1036                                 BorrowedRef { ref mut type_, .. } => {
1037                                     **type_ = Generic(kw::SelfUpper)
1038                                 }
1039                                 _ => unreachable!(),
1040                             }
1041                         }
1042                     }
1043                 }
1044
1045                 let provided = match self.container {
1046                     ty::ImplContainer(_) => true,
1047                     ty::TraitContainer(_) => self.defaultness.has_value(),
1048                 };
1049                 if provided {
1050                     let constness = if tcx.is_const_fn_raw(self.def_id) {
1051                         hir::Constness::Const
1052                     } else {
1053                         hir::Constness::NotConst
1054                     };
1055                     let asyncness = tcx.asyncness(self.def_id);
1056                     let defaultness = match self.container {
1057                         ty::ImplContainer(_) => Some(self.defaultness),
1058                         ty::TraitContainer(_) => None,
1059                     };
1060                     MethodItem(
1061                         Function {
1062                             generics,
1063                             decl,
1064                             header: hir::FnHeader {
1065                                 unsafety: sig.unsafety(),
1066                                 abi: sig.abi(),
1067                                 constness,
1068                                 asyncness,
1069                             },
1070                         },
1071                         defaultness,
1072                     )
1073                 } else {
1074                     TyMethodItem(Function {
1075                         generics,
1076                         decl,
1077                         header: hir::FnHeader {
1078                             unsafety: sig.unsafety(),
1079                             abi: sig.abi(),
1080                             constness: hir::Constness::NotConst,
1081                             asyncness: hir::IsAsync::NotAsync,
1082                         },
1083                     })
1084                 }
1085             }
1086             ty::AssocKind::Type => {
1087                 let my_name = self.ident.name;
1088
1089                 if let ty::TraitContainer(_) = self.container {
1090                     let bounds = tcx.explicit_item_bounds(self.def_id);
1091                     let predicates = ty::GenericPredicates { parent: None, predicates: bounds };
1092                     let generics = (tcx.generics_of(self.def_id), predicates).clean(cx);
1093                     let mut bounds = generics
1094                         .where_predicates
1095                         .iter()
1096                         .filter_map(|pred| {
1097                             let (name, self_type, trait_, bounds) = match *pred {
1098                                 WherePredicate::BoundPredicate {
1099                                     ty: QPath { ref name, ref self_type, ref trait_, .. },
1100                                     ref bounds,
1101                                     ..
1102                                 } => (name, self_type, trait_, bounds),
1103                                 _ => return None,
1104                             };
1105                             if *name != my_name {
1106                                 return None;
1107                             }
1108                             match **trait_ {
1109                                 ResolvedPath { did, .. } if did == self.container.id() => {}
1110                                 _ => return None,
1111                             }
1112                             match **self_type {
1113                                 Generic(ref s) if *s == kw::SelfUpper => {}
1114                                 _ => return None,
1115                             }
1116                             Some(bounds)
1117                         })
1118                         .flat_map(|i| i.iter().cloned())
1119                         .collect::<Vec<_>>();
1120                     // Our Sized/?Sized bound didn't get handled when creating the generics
1121                     // because we didn't actually get our whole set of bounds until just now
1122                     // (some of them may have come from the trait). If we do have a sized
1123                     // bound, we remove it, and if we don't then we add the `?Sized` bound
1124                     // at the end.
1125                     match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1126                         Some(i) => {
1127                             bounds.remove(i);
1128                         }
1129                         None => bounds.push(GenericBound::maybe_sized(cx)),
1130                     }
1131
1132                     let ty = if self.defaultness.has_value() {
1133                         Some(tcx.type_of(self.def_id))
1134                     } else {
1135                         None
1136                     };
1137
1138                     AssocTypeItem(bounds, ty.clean(cx))
1139                 } else {
1140                     // FIXME: when could this happen? Associated items in inherent impls?
1141                     let type_ = tcx.type_of(self.def_id).clean(cx);
1142                     TypedefItem(
1143                         Typedef {
1144                             type_,
1145                             generics: Generics { params: Vec::new(), where_predicates: Vec::new() },
1146                             item_type: None,
1147                         },
1148                         true,
1149                     )
1150                 }
1151             }
1152         };
1153
1154         Item::from_def_id_and_parts(self.def_id, Some(self.ident.name), kind, cx)
1155     }
1156 }
1157
1158 fn clean_qpath(hir_ty: &hir::Ty<'_>, cx: &mut DocContext<'_>) -> Type {
1159     use rustc_hir::GenericParamCount;
1160     let hir::Ty { hir_id: _, span, ref kind } = *hir_ty;
1161     let qpath = match kind {
1162         hir::TyKind::Path(qpath) => qpath,
1163         _ => unreachable!(),
1164     };
1165
1166     match qpath {
1167         hir::QPath::Resolved(None, ref path) => {
1168             if let Res::Def(DefKind::TyParam, did) = path.res {
1169                 if let Some(new_ty) = cx.ty_substs.get(&did).cloned() {
1170                     return new_ty;
1171                 }
1172                 if let Some(bounds) = cx.impl_trait_bounds.remove(&did.into()) {
1173                     return ImplTrait(bounds);
1174                 }
1175             }
1176
1177             let mut alias = None;
1178             if let Res::Def(DefKind::TyAlias, def_id) = path.res {
1179                 // Substitute private type aliases
1180                 if let Some(def_id) = def_id.as_local() {
1181                     let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
1182                     if !cx.cache.access_levels.is_exported(def_id.to_def_id()) {
1183                         alias = Some(&cx.tcx.hir().expect_item(hir_id).kind);
1184                     }
1185                 }
1186             };
1187
1188             if let Some(&hir::ItemKind::TyAlias(ref ty, ref generics)) = alias {
1189                 let provided_params = &path.segments.last().expect("segments were empty");
1190                 let mut ty_substs = FxHashMap::default();
1191                 let mut lt_substs = FxHashMap::default();
1192                 let mut ct_substs = FxHashMap::default();
1193                 let generic_args = provided_params.args();
1194                 {
1195                     let mut indices: GenericParamCount = Default::default();
1196                     for param in generics.params.iter() {
1197                         match param.kind {
1198                             hir::GenericParamKind::Lifetime { .. } => {
1199                                 let mut j = 0;
1200                                 let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1201                                     hir::GenericArg::Lifetime(lt) => {
1202                                         if indices.lifetimes == j {
1203                                             return Some(lt);
1204                                         }
1205                                         j += 1;
1206                                         None
1207                                     }
1208                                     _ => None,
1209                                 });
1210                                 if let Some(lt) = lifetime.cloned() {
1211                                     let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1212                                     let cleaned = if !lt.is_elided() {
1213                                         lt.clean(cx)
1214                                     } else {
1215                                         self::types::Lifetime::elided()
1216                                     };
1217                                     lt_substs.insert(lt_def_id.to_def_id(), cleaned);
1218                                 }
1219                                 indices.lifetimes += 1;
1220                             }
1221                             hir::GenericParamKind::Type { ref default, .. } => {
1222                                 let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1223                                 let mut j = 0;
1224                                 let type_ = generic_args.args.iter().find_map(|arg| match arg {
1225                                     hir::GenericArg::Type(ty) => {
1226                                         if indices.types == j {
1227                                             return Some(ty);
1228                                         }
1229                                         j += 1;
1230                                         None
1231                                     }
1232                                     _ => None,
1233                                 });
1234                                 if let Some(ty) = type_ {
1235                                     ty_substs.insert(ty_param_def_id.to_def_id(), ty.clean(cx));
1236                                 } else if let Some(default) = *default {
1237                                     ty_substs
1238                                         .insert(ty_param_def_id.to_def_id(), default.clean(cx));
1239                                 }
1240                                 indices.types += 1;
1241                             }
1242                             hir::GenericParamKind::Const { .. } => {
1243                                 let const_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1244                                 let mut j = 0;
1245                                 let const_ = generic_args.args.iter().find_map(|arg| match arg {
1246                                     hir::GenericArg::Const(ct) => {
1247                                         if indices.consts == j {
1248                                             return Some(ct);
1249                                         }
1250                                         j += 1;
1251                                         None
1252                                     }
1253                                     _ => None,
1254                                 });
1255                                 if let Some(ct) = const_ {
1256                                     ct_substs.insert(const_param_def_id.to_def_id(), ct.clean(cx));
1257                                 }
1258                                 // FIXME(const_generics_defaults)
1259                                 indices.consts += 1;
1260                             }
1261                         }
1262                     }
1263                 }
1264                 return cx.enter_alias(ty_substs, lt_substs, ct_substs, |cx| ty.clean(cx));
1265             }
1266             let path = path.clean(cx);
1267             resolve_type(cx, path)
1268         }
1269         hir::QPath::Resolved(Some(ref qself), ref p) => {
1270             // Try to normalize `<X as Y>::T` to a type
1271             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1272             if let Some(normalized_value) = normalize(cx, ty) {
1273                 return normalized_value.clean(cx);
1274             }
1275
1276             let segments = if p.is_global() { &p.segments[1..] } else { &p.segments };
1277             let trait_segments = &segments[..segments.len() - 1];
1278             let trait_def = cx.tcx.associated_item(p.res.def_id()).container.id();
1279             let trait_path = self::Path {
1280                 global: p.is_global(),
1281                 res: Res::Def(DefKind::Trait, trait_def),
1282                 segments: trait_segments.clean(cx),
1283             };
1284             Type::QPath {
1285                 name: p.segments.last().expect("segments were empty").ident.name,
1286                 self_def_id: Some(DefId::local(qself.hir_id.owner.local_def_index)),
1287                 self_type: Box::new(qself.clean(cx)),
1288                 trait_: Box::new(resolve_type(cx, trait_path)),
1289             }
1290         }
1291         hir::QPath::TypeRelative(ref qself, ref segment) => {
1292             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1293             let res = match ty.kind() {
1294                 ty::Projection(proj) => Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id),
1295                 // Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
1296                 ty::Error(_) => return Type::Infer,
1297                 _ => bug!("clean: expected associated type, found `{:?}`", ty),
1298             };
1299             let trait_path = hir::Path { span, res, segments: &[] }.clean(cx);
1300             Type::QPath {
1301                 name: segment.ident.name,
1302                 self_def_id: res.opt_def_id(),
1303                 self_type: Box::new(qself.clean(cx)),
1304                 trait_: Box::new(resolve_type(cx, trait_path)),
1305             }
1306         }
1307         hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1308     }
1309 }
1310
1311 impl Clean<Type> for hir::Ty<'_> {
1312     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
1313         use rustc_hir::*;
1314
1315         match self.kind {
1316             TyKind::Never => Never,
1317             TyKind::Ptr(ref m) => RawPointer(m.mutbl, Box::new(m.ty.clean(cx))),
1318             TyKind::Rptr(ref l, ref m) => {
1319                 // There are two times a `Fresh` lifetime can be created:
1320                 // 1. For `&'_ x`, written by the user. This corresponds to `lower_lifetime` in `rustc_ast_lowering`.
1321                 // 2. For `&x` as a parameter to an `async fn`. This corresponds to `elided_ref_lifetime in `rustc_ast_lowering`.
1322                 //    See #59286 for more information.
1323                 // Ideally we would only hide the `'_` for case 2., but I don't know a way to distinguish it.
1324                 // Turning `fn f(&'_ self)` into `fn f(&self)` isn't the worst thing in the world, though;
1325                 // there's no case where it could cause the function to fail to compile.
1326                 let elided =
1327                     l.is_elided() || matches!(l.name, LifetimeName::Param(ParamName::Fresh(_)));
1328                 let lifetime = if elided { None } else { Some(l.clean(cx)) };
1329                 BorrowedRef { lifetime, mutability: m.mutbl, type_: Box::new(m.ty.clean(cx)) }
1330             }
1331             TyKind::Slice(ref ty) => Slice(Box::new(ty.clean(cx))),
1332             TyKind::Array(ref ty, ref length) => {
1333                 let def_id = cx.tcx.hir().local_def_id(length.hir_id);
1334                 // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1335                 // as we currently do not supply the parent generics to anonymous constants
1336                 // but do allow `ConstKind::Param`.
1337                 //
1338                 // `const_eval_poly` tries to to first substitute generic parameters which
1339                 // results in an ICE while manually constructing the constant and using `eval`
1340                 // does nothing for `ConstKind::Param`.
1341                 let ct = ty::Const::from_anon_const(cx.tcx, def_id);
1342                 let param_env = cx.tcx.param_env(def_id);
1343                 let length = print_const(cx, ct.eval(cx.tcx, param_env));
1344                 Array(Box::new(ty.clean(cx)), length)
1345             }
1346             TyKind::Tup(ref tys) => Tuple(tys.clean(cx)),
1347             TyKind::OpaqueDef(item_id, _) => {
1348                 let item = cx.tcx.hir().item(item_id);
1349                 if let hir::ItemKind::OpaqueTy(ref ty) = item.kind {
1350                     ImplTrait(ty.bounds.clean(cx))
1351                 } else {
1352                     unreachable!()
1353                 }
1354             }
1355             TyKind::Path(_) => clean_qpath(&self, cx),
1356             TyKind::TraitObject(ref bounds, ref lifetime, _) => {
1357                 let bounds = bounds.iter().map(|bound| bound.clean(cx)).collect();
1358                 let lifetime = if !lifetime.is_elided() { Some(lifetime.clean(cx)) } else { None };
1359                 DynTrait(bounds, lifetime)
1360             }
1361             TyKind::BareFn(ref barefn) => BareFunction(Box::new(barefn.clean(cx))),
1362             // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
1363             TyKind::Infer | TyKind::Err => Infer,
1364             TyKind::Typeof(..) => panic!("unimplemented type {:?}", self.kind),
1365         }
1366     }
1367 }
1368
1369 /// Returns `None` if the type could not be normalized
1370 fn normalize(cx: &mut DocContext<'tcx>, ty: Ty<'_>) -> Option<Ty<'tcx>> {
1371     // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1372     if !cx.tcx.sess.opts.debugging_opts.normalize_docs {
1373         return None;
1374     }
1375
1376     use crate::rustc_trait_selection::infer::TyCtxtInferExt;
1377     use crate::rustc_trait_selection::traits::query::normalize::AtExt;
1378     use rustc_middle::traits::ObligationCause;
1379
1380     // Try to normalize `<X as Y>::T` to a type
1381     let lifted = ty.lift_to_tcx(cx.tcx).unwrap();
1382     let normalized = cx.tcx.infer_ctxt().enter(|infcx| {
1383         infcx
1384             .at(&ObligationCause::dummy(), cx.param_env)
1385             .normalize(lifted)
1386             .map(|resolved| infcx.resolve_vars_if_possible(resolved.value))
1387     });
1388     match normalized {
1389         Ok(normalized_value) => {
1390             debug!("normalized {:?} to {:?}", ty, normalized_value);
1391             Some(normalized_value)
1392         }
1393         Err(err) => {
1394             debug!("failed to normalize {:?}: {:?}", ty, err);
1395             None
1396         }
1397     }
1398 }
1399
1400 impl<'tcx> Clean<Type> for Ty<'tcx> {
1401     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
1402         trace!("cleaning type: {:?}", self);
1403         let ty = normalize(cx, self).unwrap_or(self);
1404         match *ty.kind() {
1405             ty::Never => Never,
1406             ty::Bool => Primitive(PrimitiveType::Bool),
1407             ty::Char => Primitive(PrimitiveType::Char),
1408             ty::Int(int_ty) => Primitive(int_ty.into()),
1409             ty::Uint(uint_ty) => Primitive(uint_ty.into()),
1410             ty::Float(float_ty) => Primitive(float_ty.into()),
1411             ty::Str => Primitive(PrimitiveType::Str),
1412             ty::Slice(ty) => Slice(Box::new(ty.clean(cx))),
1413             ty::Array(ty, n) => {
1414                 let mut n = cx.tcx.lift(n).expect("array lift failed");
1415                 n = n.eval(cx.tcx, ty::ParamEnv::reveal_all());
1416                 let n = print_const(cx, n);
1417                 Array(Box::new(ty.clean(cx)), n)
1418             }
1419             ty::RawPtr(mt) => RawPointer(mt.mutbl, Box::new(mt.ty.clean(cx))),
1420             ty::Ref(r, ty, mutbl) => BorrowedRef {
1421                 lifetime: r.clean(cx),
1422                 mutability: mutbl,
1423                 type_: Box::new(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::new(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, is_generic: false }
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, is_generic: false }
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 {
1476                         trait_: ResolvedPath { path, did, is_generic: false },
1477                         generic_params: Vec::new(),
1478                     };
1479                     bounds.push(bound);
1480                 }
1481
1482                 let mut bindings = vec![];
1483                 for pb in obj.projection_bounds() {
1484                     bindings.push(TypeBinding {
1485                         name: cx.tcx.associated_item(pb.item_def_id()).ident.name,
1486                         kind: TypeBindingKind::Equality { ty: pb.skip_binder().ty.clean(cx) },
1487                     });
1488                 }
1489
1490                 let path = external_path(cx, did, false, bindings, substs);
1491                 bounds.insert(
1492                     0,
1493                     PolyTrait {
1494                         trait_: ResolvedPath { path, did, is_generic: false },
1495                         generic_params: Vec::new(),
1496                     },
1497                 );
1498
1499                 DynTrait(bounds, lifetime)
1500             }
1501             ty::Tuple(ref t) => {
1502                 Tuple(t.iter().map(|t| t.expect_ty()).collect::<Vec<_>>().clean(cx))
1503             }
1504
1505             ty::Projection(ref data) => data.clean(cx),
1506
1507             ty::Param(ref p) => {
1508                 if let Some(bounds) = cx.impl_trait_bounds.remove(&p.index.into()) {
1509                     ImplTrait(bounds)
1510                 } else {
1511                     Generic(p.name)
1512                 }
1513             }
1514
1515             ty::Opaque(def_id, substs) => {
1516                 // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1517                 // by looking up the bounds associated with the def_id.
1518                 let substs = cx.tcx.lift(substs).expect("Opaque lift failed");
1519                 let bounds = cx
1520                     .tcx
1521                     .explicit_item_bounds(def_id)
1522                     .iter()
1523                     .map(|(bound, _)| bound.subst(cx.tcx, substs))
1524                     .collect::<Vec<_>>();
1525                 let mut regions = vec![];
1526                 let mut has_sized = false;
1527                 let mut bounds = bounds
1528                     .iter()
1529                     .filter_map(|bound| {
1530                         let bound_predicate = bound.kind();
1531                         let trait_ref = match bound_predicate.skip_binder() {
1532                             ty::PredicateKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
1533                             ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
1534                                 if let Some(r) = reg.clean(cx) {
1535                                     regions.push(GenericBound::Outlives(r));
1536                                 }
1537                                 return None;
1538                             }
1539                             _ => return None,
1540                         };
1541
1542                         if let Some(sized) = cx.tcx.lang_items().sized_trait() {
1543                             if trait_ref.def_id() == sized {
1544                                 has_sized = true;
1545                                 return None;
1546                             }
1547                         }
1548
1549                         let bounds: Vec<_> = bounds
1550                             .iter()
1551                             .filter_map(|bound| {
1552                                 if let ty::PredicateKind::Projection(proj) =
1553                                     bound.kind().skip_binder()
1554                                 {
1555                                     if proj.projection_ty.trait_ref(cx.tcx)
1556                                         == trait_ref.skip_binder()
1557                                     {
1558                                         Some(TypeBinding {
1559                                             name: cx
1560                                                 .tcx
1561                                                 .associated_item(proj.projection_ty.item_def_id)
1562                                                 .ident
1563                                                 .name,
1564                                             kind: TypeBindingKind::Equality {
1565                                                 ty: proj.ty.clean(cx),
1566                                             },
1567                                         })
1568                                     } else {
1569                                         None
1570                                     }
1571                                 } else {
1572                                     None
1573                                 }
1574                             })
1575                             .collect();
1576
1577                         Some((trait_ref, &bounds[..]).clean(cx))
1578                     })
1579                     .collect::<Vec<_>>();
1580                 bounds.extend(regions);
1581                 if !has_sized && !bounds.is_empty() {
1582                     bounds.insert(0, GenericBound::maybe_sized(cx));
1583                 }
1584                 ImplTrait(bounds)
1585             }
1586
1587             ty::Closure(..) | ty::Generator(..) => Tuple(vec![]), // FIXME(pcwalton)
1588
1589             ty::Bound(..) => panic!("Bound"),
1590             ty::Placeholder(..) => panic!("Placeholder"),
1591             ty::GeneratorWitness(..) => panic!("GeneratorWitness"),
1592             ty::Infer(..) => panic!("Infer"),
1593             ty::Error(_) => panic!("Error"),
1594         }
1595     }
1596 }
1597
1598 impl<'tcx> Clean<Constant> for ty::Const<'tcx> {
1599     fn clean(&self, cx: &mut DocContext<'_>) -> Constant {
1600         // FIXME: instead of storing the stringified expression, store `self` directly instead.
1601         Constant {
1602             type_: self.ty.clean(cx),
1603             kind: ConstantKind::TyConst { expr: self.to_string() },
1604         }
1605     }
1606 }
1607
1608 impl Clean<Item> for hir::FieldDef<'_> {
1609     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1610         let what_rustc_thinks = Item::from_hir_id_and_parts(
1611             self.hir_id,
1612             Some(self.ident.name),
1613             StructFieldItem(self.ty.clean(cx)),
1614             cx,
1615         );
1616         // Don't show `pub` for fields on enum variants; they are always public
1617         Item { visibility: self.vis.clean(cx), ..what_rustc_thinks }
1618     }
1619 }
1620
1621 impl Clean<Item> for ty::FieldDef {
1622     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1623         let what_rustc_thinks = Item::from_def_id_and_parts(
1624             self.did,
1625             Some(self.ident.name),
1626             StructFieldItem(cx.tcx.type_of(self.did).clean(cx)),
1627             cx,
1628         );
1629         // Don't show `pub` for fields on enum variants; they are always public
1630         Item { visibility: self.vis.clean(cx), ..what_rustc_thinks }
1631     }
1632 }
1633
1634 impl Clean<Visibility> for hir::Visibility<'_> {
1635     fn clean(&self, cx: &mut DocContext<'_>) -> Visibility {
1636         match self.node {
1637             hir::VisibilityKind::Public => Visibility::Public,
1638             hir::VisibilityKind::Inherited => Visibility::Inherited,
1639             hir::VisibilityKind::Crate(_) => {
1640                 let krate = DefId::local(CRATE_DEF_INDEX);
1641                 Visibility::Restricted(krate)
1642             }
1643             hir::VisibilityKind::Restricted { ref path, .. } => {
1644                 let path = path.clean(cx);
1645                 let did = register_res(cx, path.res);
1646                 Visibility::Restricted(did)
1647             }
1648         }
1649     }
1650 }
1651
1652 impl Clean<Visibility> for ty::Visibility {
1653     fn clean(&self, _cx: &mut DocContext<'_>) -> Visibility {
1654         match *self {
1655             ty::Visibility::Public => Visibility::Public,
1656             // NOTE: this is not quite right: `ty` uses `Invisible` to mean 'private',
1657             // while rustdoc really does mean inherited. That means that for enum variants, such as
1658             // `pub enum E { V }`, `V` will be marked as `Public` by `ty`, but as `Inherited` by rustdoc.
1659             // This is the main reason `impl Clean for hir::Visibility` still exists; various parts of clean
1660             // override `tcx.visibility` explicitly to make sure this distinction is captured.
1661             ty::Visibility::Invisible => Visibility::Inherited,
1662             ty::Visibility::Restricted(module) => Visibility::Restricted(module),
1663         }
1664     }
1665 }
1666
1667 impl Clean<VariantStruct> for rustc_hir::VariantData<'_> {
1668     fn clean(&self, cx: &mut DocContext<'_>) -> VariantStruct {
1669         VariantStruct {
1670             struct_type: CtorKind::from_hir(self),
1671             fields: self.fields().iter().map(|x| x.clean(cx)).collect(),
1672             fields_stripped: false,
1673         }
1674     }
1675 }
1676
1677 impl Clean<Vec<Item>> for hir::VariantData<'_> {
1678     fn clean(&self, cx: &mut DocContext<'_>) -> Vec<Item> {
1679         self.fields().iter().map(|x| x.clean(cx)).collect()
1680     }
1681 }
1682
1683 impl Clean<Item> for ty::VariantDef {
1684     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1685         let kind = match self.ctor_kind {
1686             CtorKind::Const => Variant::CLike,
1687             CtorKind::Fn => Variant::Tuple(
1688                 self.fields
1689                     .iter()
1690                     .map(|field| {
1691                         let name = Some(field.ident.name);
1692                         let kind = StructFieldItem(cx.tcx.type_of(field.did).clean(cx));
1693                         let what_rustc_thinks =
1694                             Item::from_def_id_and_parts(field.did, name, kind, cx);
1695                         // don't show `pub` for fields, which are always public
1696                         Item { visibility: Visibility::Inherited, ..what_rustc_thinks }
1697                     })
1698                     .collect(),
1699             ),
1700             CtorKind::Fictive => Variant::Struct(VariantStruct {
1701                 struct_type: CtorKind::Fictive,
1702                 fields_stripped: false,
1703                 fields: self
1704                     .fields
1705                     .iter()
1706                     .map(|field| {
1707                         let name = Some(field.ident.name);
1708                         let kind = StructFieldItem(cx.tcx.type_of(field.did).clean(cx));
1709                         let what_rustc_thinks =
1710                             Item::from_def_id_and_parts(field.did, name, kind, cx);
1711                         // don't show `pub` for fields, which are always public
1712                         Item { visibility: Visibility::Inherited, ..what_rustc_thinks }
1713                     })
1714                     .collect(),
1715             }),
1716         };
1717         let what_rustc_thinks =
1718             Item::from_def_id_and_parts(self.def_id, Some(self.ident.name), VariantItem(kind), cx);
1719         // don't show `pub` for fields, which are always public
1720         Item { visibility: Inherited, ..what_rustc_thinks }
1721     }
1722 }
1723
1724 impl Clean<Variant> for hir::VariantData<'_> {
1725     fn clean(&self, cx: &mut DocContext<'_>) -> Variant {
1726         match self {
1727             hir::VariantData::Struct(..) => Variant::Struct(self.clean(cx)),
1728             hir::VariantData::Tuple(..) => Variant::Tuple(self.clean(cx)),
1729             hir::VariantData::Unit(..) => Variant::CLike,
1730         }
1731     }
1732 }
1733
1734 impl Clean<Path> for hir::Path<'_> {
1735     fn clean(&self, cx: &mut DocContext<'_>) -> Path {
1736         Path {
1737             global: self.is_global(),
1738             res: self.res,
1739             segments: if self.is_global() { &self.segments[1..] } else { &self.segments }.clean(cx),
1740         }
1741     }
1742 }
1743
1744 impl Clean<GenericArgs> for hir::GenericArgs<'_> {
1745     fn clean(&self, cx: &mut DocContext<'_>) -> GenericArgs {
1746         if self.parenthesized {
1747             let output = self.bindings[0].ty().clean(cx);
1748             let output =
1749                 if output != Type::Tuple(Vec::new()) { Some(Box::new(output)) } else { None };
1750             GenericArgs::Parenthesized { inputs: self.inputs().clean(cx), output }
1751         } else {
1752             GenericArgs::AngleBracketed {
1753                 args: self
1754                     .args
1755                     .iter()
1756                     .map(|arg| match arg {
1757                         hir::GenericArg::Lifetime(lt) if !lt.is_elided() => {
1758                             GenericArg::Lifetime(lt.clean(cx))
1759                         }
1760                         hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
1761                         hir::GenericArg::Type(ty) => GenericArg::Type(ty.clean(cx)),
1762                         hir::GenericArg::Const(ct) => GenericArg::Const(Box::new(ct.clean(cx))),
1763                         hir::GenericArg::Infer(_inf) => GenericArg::Infer,
1764                     })
1765                     .collect(),
1766                 bindings: self.bindings.clean(cx),
1767             }
1768         }
1769     }
1770 }
1771
1772 impl Clean<PathSegment> for hir::PathSegment<'_> {
1773     fn clean(&self, cx: &mut DocContext<'_>) -> PathSegment {
1774         PathSegment { name: self.ident.name, args: self.args().clean(cx) }
1775     }
1776 }
1777
1778 impl Clean<BareFunctionDecl> for hir::BareFnTy<'_> {
1779     fn clean(&self, cx: &mut DocContext<'_>) -> BareFunctionDecl {
1780         let (generic_params, decl) = enter_impl_trait(cx, |cx| {
1781             (self.generic_params.clean(cx), (&*self.decl, self.param_names).clean(cx))
1782         });
1783         BareFunctionDecl { unsafety: self.unsafety, abi: self.abi, decl, generic_params }
1784     }
1785 }
1786
1787 impl Clean<Vec<Item>> for (&hir::Item<'_>, Option<Symbol>) {
1788     fn clean(&self, cx: &mut DocContext<'_>) -> Vec<Item> {
1789         use hir::ItemKind;
1790
1791         let (item, renamed) = self;
1792         let def_id = item.def_id.to_def_id();
1793         let mut name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
1794         cx.with_param_env(def_id, |cx| {
1795             let kind = match item.kind {
1796                 ItemKind::Static(ty, mutability, body_id) => {
1797                     StaticItem(Static { type_: ty.clean(cx), mutability, expr: Some(body_id) })
1798                 }
1799                 ItemKind::Const(ty, body_id) => ConstantItem(Constant {
1800                     type_: ty.clean(cx),
1801                     kind: ConstantKind::Local { body: body_id, def_id },
1802                 }),
1803                 ItemKind::OpaqueTy(ref ty) => OpaqueTyItem(OpaqueTy {
1804                     bounds: ty.bounds.clean(cx),
1805                     generics: ty.generics.clean(cx),
1806                 }),
1807                 ItemKind::TyAlias(hir_ty, ref generics) => {
1808                     let rustdoc_ty = hir_ty.clean(cx);
1809                     let ty = hir_ty_to_ty(cx.tcx, hir_ty).clean(cx);
1810                     TypedefItem(
1811                         Typedef {
1812                             type_: rustdoc_ty,
1813                             generics: generics.clean(cx),
1814                             item_type: Some(ty),
1815                         },
1816                         false,
1817                     )
1818                 }
1819                 ItemKind::Enum(ref def, ref generics) => EnumItem(Enum {
1820                     variants: def.variants.iter().map(|v| v.clean(cx)).collect(),
1821                     generics: generics.clean(cx),
1822                     variants_stripped: false,
1823                 }),
1824                 ItemKind::TraitAlias(ref generics, bounds) => TraitAliasItem(TraitAlias {
1825                     generics: generics.clean(cx),
1826                     bounds: bounds.clean(cx),
1827                 }),
1828                 ItemKind::Union(ref variant_data, ref generics) => UnionItem(Union {
1829                     generics: generics.clean(cx),
1830                     fields: variant_data.fields().clean(cx),
1831                     fields_stripped: false,
1832                 }),
1833                 ItemKind::Struct(ref variant_data, ref generics) => StructItem(Struct {
1834                     struct_type: CtorKind::from_hir(variant_data),
1835                     generics: generics.clean(cx),
1836                     fields: variant_data.fields().clean(cx),
1837                     fields_stripped: false,
1838                 }),
1839                 ItemKind::Impl(ref impl_) => return clean_impl(impl_, item.hir_id(), cx),
1840                 // proc macros can have a name set by attributes
1841                 ItemKind::Fn(ref sig, ref generics, body_id) => {
1842                     clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
1843                 }
1844                 ItemKind::Macro(ref macro_def) => MacroItem(Macro {
1845                     source: display_macro_source(cx, name, &macro_def, def_id, &item.vis),
1846                 }),
1847                 ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref item_ids) => {
1848                     let items = item_ids
1849                         .iter()
1850                         .map(|ti| cx.tcx.hir().trait_item(ti.id).clean(cx))
1851                         .collect();
1852                     TraitItem(Trait {
1853                         unsafety,
1854                         items,
1855                         generics: generics.clean(cx),
1856                         bounds: bounds.clean(cx),
1857                         is_auto: is_auto.clean(cx),
1858                     })
1859                 }
1860                 ItemKind::ExternCrate(orig_name) => {
1861                     return clean_extern_crate(item, name, orig_name, cx);
1862                 }
1863                 ItemKind::Use(path, kind) => {
1864                     return clean_use_statement(item, name, path, kind, cx);
1865                 }
1866                 _ => unreachable!("not yet converted"),
1867             };
1868
1869             vec![Item::from_def_id_and_parts(def_id, Some(name), kind, cx)]
1870         })
1871     }
1872 }
1873
1874 impl Clean<Item> for hir::Variant<'_> {
1875     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1876         let kind = VariantItem(self.data.clean(cx));
1877         let what_rustc_thinks =
1878             Item::from_hir_id_and_parts(self.id, Some(self.ident.name), kind, cx);
1879         // don't show `pub` for variants, which are always public
1880         Item { visibility: Inherited, ..what_rustc_thinks }
1881     }
1882 }
1883
1884 impl Clean<bool> for ty::ImplPolarity {
1885     /// Returns whether the impl has negative polarity.
1886     fn clean(&self, _: &mut DocContext<'_>) -> bool {
1887         match self {
1888             &ty::ImplPolarity::Positive |
1889             // FIXME: do we want to do something else here?
1890             &ty::ImplPolarity::Reservation => false,
1891             &ty::ImplPolarity::Negative => true,
1892         }
1893     }
1894 }
1895
1896 fn clean_impl(impl_: &hir::Impl<'_>, hir_id: hir::HirId, cx: &mut DocContext<'_>) -> Vec<Item> {
1897     let tcx = cx.tcx;
1898     let mut ret = Vec::new();
1899     let trait_ = impl_.of_trait.clean(cx);
1900     let items =
1901         impl_.items.iter().map(|ii| tcx.hir().impl_item(ii.id).clean(cx)).collect::<Vec<_>>();
1902     let def_id = tcx.hir().local_def_id(hir_id);
1903
1904     // If this impl block is an implementation of the Deref trait, then we
1905     // need to try inlining the target's inherent impl blocks as well.
1906     if trait_.def_id() == tcx.lang_items().deref_trait() {
1907         build_deref_target_impls(cx, &items, &mut ret);
1908     }
1909
1910     let for_ = impl_.self_ty.clean(cx);
1911     let type_alias = for_.def_id().and_then(|did| match tcx.def_kind(did) {
1912         DefKind::TyAlias => Some(tcx.type_of(did).clean(cx)),
1913         _ => None,
1914     });
1915     let mut make_item = |trait_: Option<Type>, for_: Type, items: Vec<Item>| {
1916         let kind = ImplItem(Impl {
1917             span: types::rustc_span(tcx.hir().local_def_id(hir_id).to_def_id(), tcx),
1918             unsafety: impl_.unsafety,
1919             generics: impl_.generics.clean(cx),
1920             trait_,
1921             for_,
1922             items,
1923             negative_polarity: tcx.impl_polarity(def_id).clean(cx),
1924             synthetic: false,
1925             blanket_impl: None,
1926         });
1927         Item::from_hir_id_and_parts(hir_id, None, kind, cx)
1928     };
1929     if let Some(type_alias) = type_alias {
1930         ret.push(make_item(trait_.clone(), type_alias, items.clone()));
1931     }
1932     ret.push(make_item(trait_, for_, items));
1933     ret
1934 }
1935
1936 fn clean_extern_crate(
1937     krate: &hir::Item<'_>,
1938     name: Symbol,
1939     orig_name: Option<Symbol>,
1940     cx: &mut DocContext<'_>,
1941 ) -> Vec<Item> {
1942     // this is the ID of the `extern crate` statement
1943     let cnum = cx.tcx.extern_mod_stmt_cnum(krate.def_id).unwrap_or(LOCAL_CRATE);
1944     // this is the ID of the crate itself
1945     let crate_def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
1946     let attrs = cx.tcx.hir().attrs(krate.hir_id());
1947     let please_inline = krate.vis.node.is_pub()
1948         && attrs.iter().any(|a| {
1949             a.has_name(sym::doc)
1950                 && match a.meta_item_list() {
1951                     Some(l) => attr::list_contains_name(&l, sym::inline),
1952                     None => false,
1953                 }
1954         });
1955
1956     if please_inline {
1957         let mut visited = FxHashSet::default();
1958
1959         let res = Res::Def(DefKind::Mod, crate_def_id);
1960
1961         if let Some(items) = inline::try_inline(
1962             cx,
1963             cx.tcx.parent_module(krate.hir_id()).to_def_id(),
1964             Some(krate.def_id.to_def_id()),
1965             res,
1966             name,
1967             Some(attrs),
1968             &mut visited,
1969         ) {
1970             return items;
1971         }
1972     }
1973
1974     // FIXME: using `from_def_id_and_kind` breaks `rustdoc/masked` for some reason
1975     vec![Item {
1976         name: Some(name),
1977         attrs: Box::new(attrs.clean(cx)),
1978         def_id: crate_def_id.into(),
1979         visibility: krate.vis.clean(cx),
1980         kind: Box::new(ExternCrateItem { src: orig_name }),
1981         cfg: attrs.cfg(cx.sess()),
1982     }]
1983 }
1984
1985 fn clean_use_statement(
1986     import: &hir::Item<'_>,
1987     name: Symbol,
1988     path: &hir::Path<'_>,
1989     kind: hir::UseKind,
1990     cx: &mut DocContext<'_>,
1991 ) -> Vec<Item> {
1992     // We need this comparison because some imports (for std types for example)
1993     // are "inserted" as well but directly by the compiler and they should not be
1994     // taken into account.
1995     if import.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
1996         return Vec::new();
1997     }
1998
1999     let attrs = cx.tcx.hir().attrs(import.hir_id());
2000     let inline_attr = attrs.lists(sym::doc).get_word_attr(sym::inline);
2001     let pub_underscore = import.vis.node.is_pub() && name == kw::Underscore;
2002
2003     if pub_underscore {
2004         if let Some(ref inline) = inline_attr {
2005             rustc_errors::struct_span_err!(
2006                 cx.tcx.sess,
2007                 inline.span(),
2008                 E0780,
2009                 "anonymous imports cannot be inlined"
2010             )
2011             .span_label(import.span, "anonymous import")
2012             .emit();
2013         }
2014     }
2015
2016     // We consider inlining the documentation of `pub use` statements, but we
2017     // forcefully don't inline if this is not public or if the
2018     // #[doc(no_inline)] attribute is present.
2019     // Don't inline doc(hidden) imports so they can be stripped at a later stage.
2020     let mut denied = !(import.vis.node.is_pub()
2021         || (cx.render_options.document_private && import.vis.node.is_pub_restricted()))
2022         || pub_underscore
2023         || attrs.iter().any(|a| {
2024             a.has_name(sym::doc)
2025                 && match a.meta_item_list() {
2026                     Some(l) => {
2027                         attr::list_contains_name(&l, sym::no_inline)
2028                             || attr::list_contains_name(&l, sym::hidden)
2029                     }
2030                     None => false,
2031                 }
2032         });
2033
2034     // Also check whether imports were asked to be inlined, in case we're trying to re-export a
2035     // crate in Rust 2018+
2036     let path = path.clean(cx);
2037     let inner = if kind == hir::UseKind::Glob {
2038         if !denied {
2039             let mut visited = FxHashSet::default();
2040             if let Some(items) = inline::try_inline_glob(cx, path.res, &mut visited) {
2041                 return items;
2042             }
2043         }
2044         Import::new_glob(resolve_use_source(cx, path), true)
2045     } else {
2046         if inline_attr.is_none() {
2047             if let Res::Def(DefKind::Mod, did) = path.res {
2048                 if !did.is_local() && did.index == CRATE_DEF_INDEX {
2049                     // if we're `pub use`ing an extern crate root, don't inline it unless we
2050                     // were specifically asked for it
2051                     denied = true;
2052                 }
2053             }
2054         }
2055         if !denied {
2056             let mut visited = FxHashSet::default();
2057             let import_def_id = import.def_id.to_def_id();
2058
2059             if let Some(mut items) = inline::try_inline(
2060                 cx,
2061                 cx.tcx.parent_module(import.hir_id()).to_def_id(),
2062                 Some(import_def_id),
2063                 path.res,
2064                 name,
2065                 Some(attrs),
2066                 &mut visited,
2067             ) {
2068                 items.push(Item::from_def_id_and_parts(
2069                     import_def_id,
2070                     None,
2071                     ImportItem(Import::new_simple(name, resolve_use_source(cx, path), false)),
2072                     cx,
2073                 ));
2074                 return items;
2075             }
2076         }
2077         Import::new_simple(name, resolve_use_source(cx, path), true)
2078     };
2079
2080     vec![Item::from_def_id_and_parts(import.def_id.to_def_id(), None, ImportItem(inner), cx)]
2081 }
2082
2083 impl Clean<Item> for (&hir::ForeignItem<'_>, Option<Symbol>) {
2084     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
2085         let (item, renamed) = self;
2086         cx.with_param_env(item.def_id.to_def_id(), |cx| {
2087             let kind = match item.kind {
2088                 hir::ForeignItemKind::Fn(ref decl, ref names, ref generics) => {
2089                     let abi = cx.tcx.hir().get_foreign_abi(item.hir_id());
2090                     let (generics, decl) = enter_impl_trait(cx, |cx| {
2091                         (generics.clean(cx), (&**decl, &names[..]).clean(cx))
2092                     });
2093                     ForeignFunctionItem(Function {
2094                         decl,
2095                         generics,
2096                         header: hir::FnHeader {
2097                             unsafety: if abi == Abi::RustIntrinsic {
2098                                 intrinsic_operation_unsafety(item.ident.name)
2099                             } else {
2100                                 hir::Unsafety::Unsafe
2101                             },
2102                             abi,
2103                             constness: hir::Constness::NotConst,
2104                             asyncness: hir::IsAsync::NotAsync,
2105                         },
2106                     })
2107                 }
2108                 hir::ForeignItemKind::Static(ref ty, mutability) => {
2109                     ForeignStaticItem(Static { type_: ty.clean(cx), mutability, expr: None })
2110                 }
2111                 hir::ForeignItemKind::Type => ForeignTypeItem,
2112             };
2113
2114             Item::from_hir_id_and_parts(
2115                 item.hir_id(),
2116                 Some(renamed.unwrap_or(item.ident.name)),
2117                 kind,
2118                 cx,
2119             )
2120         })
2121     }
2122 }
2123
2124 impl Clean<TypeBinding> for hir::TypeBinding<'_> {
2125     fn clean(&self, cx: &mut DocContext<'_>) -> TypeBinding {
2126         TypeBinding { name: self.ident.name, kind: self.kind.clean(cx) }
2127     }
2128 }
2129
2130 impl Clean<TypeBindingKind> for hir::TypeBindingKind<'_> {
2131     fn clean(&self, cx: &mut DocContext<'_>) -> TypeBindingKind {
2132         match *self {
2133             hir::TypeBindingKind::Equality { ref ty } => {
2134                 TypeBindingKind::Equality { ty: ty.clean(cx) }
2135             }
2136             hir::TypeBindingKind::Constraint { ref bounds } => {
2137                 TypeBindingKind::Constraint { bounds: bounds.iter().map(|b| b.clean(cx)).collect() }
2138             }
2139         }
2140     }
2141 }