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 render_macro_matchers;
   9 mod simplify;
  10 crate mod types;
  11 crate mod utils;
  12
  13 use rustc_ast as ast;
  14 use rustc_attr as attr;
  15 use rustc_const_eval::const_eval::is_unstable_const_fn;
  16 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  17 use rustc_hir as hir;
  18 use rustc_hir::def::{CtorKind, DefKind, Res};
  19 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
  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::collections::BTreeMap;
  36 use std::default::Default;
  37 use std::hash::Hash;
  38 use std::{mem, vec};
  39
  40 use crate::core::{self, DocContext, ImplTraitParam};
  41 use crate::formats::item_type::ItemType;
  42 use crate::visit_ast::Module as DocModule;
  43
  44 use utils::*;
  45
  46 crate use self::types::*;
  47 crate use self::utils::{get_auto_trait_and_blanket_impls, krate, register_res};
  48
  49 crate trait Clean<T> {
  50     fn clean(&self, cx: &mut DocContext<'_>) -> T;
  51 }
  52
  53 impl Clean<Item> for DocModule<'_> {
  54     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
  55         let mut items: Vec<Item> = vec![];
  56         items.extend(
  57             self.foreigns
  58                 .iter()
  59                 .map(|(item, renamed)| clean_maybe_renamed_foreign_item(cx, item, *renamed)),
  60         );
  61         items.extend(self.mods.iter().map(|x| x.clean(cx)));
  62         items.extend(
  63             self.items
  64                 .iter()
  65                 .flat_map(|(item, renamed)| clean_maybe_renamed_item(cx, item, *renamed)),
  66         );
  67
  68         // determine if we should display the inner contents or
  69         // the outer `mod` item for the source code.
  70
  71         let span = Span::new({
  72             let where_outer = self.where_outer(cx.tcx);
  73             let sm = cx.sess().source_map();
  74             let outer = sm.lookup_char_pos(where_outer.lo());
  75             let inner = sm.lookup_char_pos(self.where_inner.lo());
  76             if outer.file.start_pos == inner.file.start_pos {
  77                 // mod foo { ... }
  78                 where_outer
  79             } else {
  80                 // mod foo; (and a separate SourceFile for the contents)
  81                 self.where_inner
  82             }
  83         });
  84
  85         Item::from_hir_id_and_parts(
  86             self.id,
  87             Some(self.name),
  88             ModuleItem(Module { items, span }),
  89             cx,
  90         )
  91     }
  92 }
  93
  94 impl Clean<Attributes> for [ast::Attribute] {
  95     fn clean(&self, _cx: &mut DocContext<'_>) -> Attributes {
  96         Attributes::from_ast(self, None)
  97     }
  98 }
  99
 100 impl Clean<Option<GenericBound>> for hir::GenericBound<'_> {
 101     fn clean(&self, cx: &mut DocContext<'_>) -> Option<GenericBound> {
 102         Some(match *self {
 103             hir::GenericBound::Outlives(lt) => GenericBound::Outlives(lt.clean(cx)),
 104             hir::GenericBound::LangItemTrait(lang_item, span, _, generic_args) => {
 105                 let def_id = cx.tcx.require_lang_item(lang_item, Some(span));
 106
 107                 let trait_ref = ty::TraitRef::identity(cx.tcx, def_id).skip_binder();
 108
 109                 let generic_args = generic_args.clean(cx);
 110                 let bindings = match generic_args {
 111                     GenericArgs::AngleBracketed { bindings, .. } => bindings,
 112                     _ => bug!("clean: parenthesized `GenericBound::LangItemTrait`"),
 113                 };
 114
 115                 let trait_ = clean_trait_ref_with_bindings(cx, trait_ref, &bindings);
 116                 GenericBound::TraitBound(
 117                     PolyTrait { trait_, generic_params: vec![] },
 118                     hir::TraitBoundModifier::None,
 119                 )
 120             }
 121             hir::GenericBound::Trait(ref t, modifier) => {
 122                 // `T: ~const Drop` is not equivalent to `T: Drop`, and we don't currently document `~const` bounds
 123                 // because of its experimental status, so just don't show these.
 124                 if Some(t.trait_ref.trait_def_id().unwrap()) == cx.tcx.lang_items().drop_trait()
 125                     && hir::TraitBoundModifier::MaybeConst == modifier
 126                 {
 127                     return None;
 128                 }
 129                 GenericBound::TraitBound(t.clean(cx), modifier)
 130             }
 131         })
 132     }
 133 }
 134
 135 fn clean_trait_ref_with_bindings(
 136     cx: &mut DocContext<'_>,
 137     trait_ref: ty::TraitRef<'_>,
 138     bindings: &[TypeBinding],
 139 ) -> Path {
 140     let kind = cx.tcx.def_kind(trait_ref.def_id).into();
 141     if !matches!(kind, ItemType::Trait | ItemType::TraitAlias) {
 142         span_bug!(cx.tcx.def_span(trait_ref.def_id), "`TraitRef` had unexpected kind {:?}", kind);
 143     }
 144     inline::record_extern_fqn(cx, trait_ref.def_id, kind);
 145     let path = external_path(cx, trait_ref.def_id, true, bindings.to_vec(), trait_ref.substs);
 146
 147     debug!("ty::TraitRef\n  subst: {:?}\n", trait_ref.substs);
 148
 149     path
 150 }
 151
 152 impl Clean<Path> for ty::TraitRef<'_> {
 153     fn clean(&self, cx: &mut DocContext<'_>) -> Path {
 154         clean_trait_ref_with_bindings(cx, *self, &[])
 155     }
 156 }
 157
 158 fn clean_poly_trait_ref_with_bindings(
 159     cx: &mut DocContext<'_>,
 160     poly_trait_ref: ty::PolyTraitRef<'_>,
 161     bindings: &[TypeBinding],
 162 ) -> GenericBound {
 163     let poly_trait_ref = poly_trait_ref.lift_to_tcx(cx.tcx).unwrap();
 164
 165     // collect any late bound regions
 166     let late_bound_regions: Vec<_> = cx
 167         .tcx
 168         .collect_referenced_late_bound_regions(&poly_trait_ref)
 169         .into_iter()
 170         .filter_map(|br| match br {
 171             ty::BrNamed(_, name) => Some(GenericParamDef {
 172                 name,
 173                 kind: GenericParamDefKind::Lifetime { outlives: vec![] },
 174             }),
 175             _ => None,
 176         })
 177         .collect();
 178
 179     let trait_ = clean_trait_ref_with_bindings(cx, poly_trait_ref.skip_binder(), bindings);
 180     GenericBound::TraitBound(
 181         PolyTrait { trait_, generic_params: late_bound_regions },
 182         hir::TraitBoundModifier::None,
 183     )
 184 }
 185
 186 impl<'tcx> Clean<GenericBound> for ty::PolyTraitRef<'tcx> {
 187     fn clean(&self, cx: &mut DocContext<'_>) -> GenericBound {
 188         clean_poly_trait_ref_with_bindings(cx, *self, &[])
 189     }
 190 }
 191
 192 impl Clean<Lifetime> for hir::Lifetime {
 193     fn clean(&self, cx: &mut DocContext<'_>) -> Lifetime {
 194         let def = cx.tcx.named_region(self.hir_id);
 195         if let Some(
 196             rl::Region::EarlyBound(_, node_id)
 197             | rl::Region::LateBound(_, _, node_id)
 198             | rl::Region::Free(_, node_id),
 199         ) = def
 200         {
 201             if let Some(lt) = cx.substs.get(&node_id).and_then(|p| p.as_lt()).cloned() {
 202                 return lt;
 203             }
 204         }
 205         Lifetime(self.name.ident().name)
 206     }
 207 }
 208
 209 impl Clean<Constant> for hir::ConstArg {
 210     fn clean(&self, cx: &mut DocContext<'_>) -> Constant {
 211         Constant {
 212             type_: cx
 213                 .tcx
 214                 .type_of(cx.tcx.hir().body_owner_def_id(self.value.body).to_def_id())
 215                 .clean(cx),
 216             kind: ConstantKind::Anonymous { body: self.value.body },
 217         }
 218     }
 219 }
 220
 221 impl Clean<Option<Lifetime>> for ty::Region<'_> {
 222     fn clean(&self, _cx: &mut DocContext<'_>) -> Option<Lifetime> {
 223         match **self {
 224             ty::ReStatic => Some(Lifetime::statik()),
 225             ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => {
 226                 Some(Lifetime(name))
 227             }
 228             ty::ReEarlyBound(ref data) => Some(Lifetime(data.name)),
 229
 230             ty::ReLateBound(..)
 231             | ty::ReFree(..)
 232             | ty::ReVar(..)
 233             | ty::RePlaceholder(..)
 234             | ty::ReEmpty(_)
 235             | ty::ReErased => {
 236                 debug!("cannot clean region {:?}", self);
 237                 None
 238             }
 239         }
 240     }
 241 }
 242
 243 impl Clean<WherePredicate> for hir::WherePredicate<'_> {
 244     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
 245         match *self {
 246             hir::WherePredicate::BoundPredicate(ref wbp) => {
 247                 let bound_params = wbp
 248                     .bound_generic_params
 249                     .into_iter()
 250                     .map(|param| {
 251                         // Higher-ranked params must be lifetimes.
 252                         // Higher-ranked lifetimes can't have bounds.
 253                         assert_matches!(
 254                             param,
 255                             hir::GenericParam {
 256                                 kind: hir::GenericParamKind::Lifetime { .. },
 257                                 bounds: [],
 258                                 ..
 259                             }
 260                         );
 261                         Lifetime(param.name.ident().name)
 262                     })
 263                     .collect();
 264                 WherePredicate::BoundPredicate {
 265                     ty: wbp.bounded_ty.clean(cx),
 266                     bounds: wbp.bounds.iter().filter_map(|x| x.clean(cx)).collect(),
 267                     bound_params,
 268                 }
 269             }
 270
 271             hir::WherePredicate::RegionPredicate(ref wrp) => WherePredicate::RegionPredicate {
 272                 lifetime: wrp.lifetime.clean(cx),
 273                 bounds: wrp.bounds.iter().filter_map(|x| x.clean(cx)).collect(),
 274             },
 275
 276             hir::WherePredicate::EqPredicate(ref wrp) => WherePredicate::EqPredicate {
 277                 lhs: wrp.lhs_ty.clean(cx),
 278                 rhs: wrp.rhs_ty.clean(cx).into(),
 279             },
 280         }
 281     }
 282 }
 283
 284 impl<'a> Clean<Option<WherePredicate>> for ty::Predicate<'a> {
 285     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 286         let bound_predicate = self.kind();
 287         match bound_predicate.skip_binder() {
 288             ty::PredicateKind::Trait(pred) => bound_predicate.rebind(pred).clean(cx),
 289             ty::PredicateKind::RegionOutlives(pred) => pred.clean(cx),
 290             ty::PredicateKind::TypeOutlives(pred) => pred.clean(cx),
 291             ty::PredicateKind::Projection(pred) => Some(pred.clean(cx)),
 292             ty::PredicateKind::ConstEvaluatable(..) => None,
 293
 294             ty::PredicateKind::Subtype(..)
 295             | ty::PredicateKind::Coerce(..)
 296             | ty::PredicateKind::WellFormed(..)
 297             | ty::PredicateKind::ObjectSafe(..)
 298             | ty::PredicateKind::ClosureKind(..)
 299             | ty::PredicateKind::ConstEquate(..)
 300             | ty::PredicateKind::TypeWellFormedFromEnv(..) => panic!("not user writable"),
 301         }
 302     }
 303 }
 304
 305 impl<'a> Clean<Option<WherePredicate>> for ty::PolyTraitPredicate<'a> {
 306     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 307         // `T: ~const Drop` is not equivalent to `T: Drop`, and we don't currently document `~const` bounds
 308         // because of its experimental status, so just don't show these.
 309         if self.skip_binder().constness == ty::BoundConstness::ConstIfConst
 310             && Some(self.skip_binder().trait_ref.def_id) == cx.tcx.lang_items().drop_trait()
 311         {
 312             return None;
 313         }
 314
 315         let poly_trait_ref = self.map_bound(|pred| pred.trait_ref);
 316         Some(WherePredicate::BoundPredicate {
 317             ty: poly_trait_ref.skip_binder().self_ty().clean(cx),
 318             bounds: vec![poly_trait_ref.clean(cx)],
 319             bound_params: Vec::new(),
 320         })
 321     }
 322 }
 323
 324 impl<'tcx> Clean<Option<WherePredicate>>
 325     for ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
 326 {
 327     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 328         let ty::OutlivesPredicate(a, b) = self;
 329
 330         if a.is_empty() && b.is_empty() {
 331             return None;
 332         }
 333
 334         Some(WherePredicate::RegionPredicate {
 335             lifetime: a.clean(cx).expect("failed to clean lifetime"),
 336             bounds: vec![GenericBound::Outlives(b.clean(cx).expect("failed to clean bounds"))],
 337         })
 338     }
 339 }
 340
 341 impl<'tcx> Clean<Option<WherePredicate>> for ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>> {
 342     fn clean(&self, cx: &mut DocContext<'_>) -> Option<WherePredicate> {
 343         let ty::OutlivesPredicate(ty, lt) = self;
 344
 345         if lt.is_empty() {
 346             return None;
 347         }
 348
 349         Some(WherePredicate::BoundPredicate {
 350             ty: ty.clean(cx),
 351             bounds: vec![GenericBound::Outlives(lt.clean(cx).expect("failed to clean lifetimes"))],
 352             bound_params: Vec::new(),
 353         })
 354     }
 355 }
 356
 357 impl<'tcx> Clean<Term> for ty::Term<'tcx> {
 358     fn clean(&self, cx: &mut DocContext<'_>) -> Term {
 359         match self {
 360             ty::Term::Ty(ty) => Term::Type(ty.clean(cx)),
 361             ty::Term::Const(c) => Term::Constant(c.clean(cx)),
 362         }
 363     }
 364 }
 365
 366 impl<'tcx> Clean<Term> for hir::Term<'tcx> {
 367     fn clean(&self, cx: &mut DocContext<'_>) -> Term {
 368         match self {
 369             hir::Term::Ty(ty) => Term::Type(ty.clean(cx)),
 370             hir::Term::Const(c) => {
 371                 let def_id = cx.tcx.hir().local_def_id(c.hir_id);
 372                 Term::Constant(ty::Const::from_anon_const(cx.tcx, def_id).clean(cx))
 373             }
 374         }
 375     }
 376 }
 377
 378 impl<'tcx> Clean<WherePredicate> for ty::ProjectionPredicate<'tcx> {
 379     fn clean(&self, cx: &mut DocContext<'_>) -> WherePredicate {
 380         let ty::ProjectionPredicate { projection_ty, term } = self;
 381         WherePredicate::EqPredicate { lhs: projection_ty.clean(cx), rhs: term.clean(cx) }
 382     }
 383 }
 384
 385 impl<'tcx> Clean<Type> for ty::ProjectionTy<'tcx> {
 386     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
 387         let lifted = self.lift_to_tcx(cx.tcx).unwrap();
 388         let trait_ = lifted.trait_ref(cx.tcx).clean(cx);
 389         let self_type = self.self_ty().clean(cx);
 390         Type::QPath {
 391             name: cx.tcx.associated_item(self.item_def_id).name,
 392             self_def_id: self_type.def_id(&cx.cache),
 393             self_type: box self_type,
 394             trait_,
 395         }
 396     }
 397 }
 398
 399 impl Clean<GenericParamDef> for ty::GenericParamDef {
 400     fn clean(&self, cx: &mut DocContext<'_>) -> GenericParamDef {
 401         let (name, kind) = match self.kind {
 402             ty::GenericParamDefKind::Lifetime => {
 403                 (self.name, GenericParamDefKind::Lifetime { outlives: vec![] })
 404             }
 405             ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
 406                 let default = if has_default {
 407                     let mut default = cx.tcx.type_of(self.def_id).clean(cx);
 408
 409                     // We need to reassign the `self_def_id`, if there's a parent (which is the
 410                     // `Self` type), so we can properly render `<Self as X>` casts, because the
 411                     // information about which type `Self` is, is only present here, but not in
 412                     // the cleaning process of the type itself. To resolve this and have the
 413                     // `self_def_id` set, we override it here.
 414                     // See https://github.com/rust-lang/rust/issues/85454
 415                     if let QPath { ref mut self_def_id, .. } = default {
 416                         *self_def_id = cx.tcx.parent(self.def_id);
 417                     }
 418
 419                     Some(default)
 420                 } else {
 421                     None
 422                 };
 423                 (
 424                     self.name,
 425                     GenericParamDefKind::Type {
 426                         did: self.def_id,
 427                         bounds: vec![], // These are filled in from the where-clauses.
 428                         default: default.map(Box::new),
 429                         synthetic,
 430                     },
 431                 )
 432             }
 433             ty::GenericParamDefKind::Const { has_default, .. } => (
 434                 self.name,
 435                 GenericParamDefKind::Const {
 436                     did: self.def_id,
 437                     ty: Box::new(cx.tcx.type_of(self.def_id).clean(cx)),
 438                     default: match has_default {
 439                         true => Some(Box::new(cx.tcx.const_param_default(self.def_id).to_string())),
 440                         false => None,
 441                     },
 442                 },
 443             ),
 444         };
 445
 446         GenericParamDef { name, kind }
 447     }
 448 }
 449
 450 impl Clean<GenericParamDef> for hir::GenericParam<'_> {
 451     fn clean(&self, cx: &mut DocContext<'_>) -> GenericParamDef {
 452         let (name, kind) = match self.kind {
 453             hir::GenericParamKind::Lifetime { .. } => {
 454                 let outlives = self
 455                     .bounds
 456                     .iter()
 457                     .map(|bound| match bound {
 458                         hir::GenericBound::Outlives(lt) => lt.clean(cx),
 459                         _ => panic!(),
 460                     })
 461                     .collect();
 462                 (self.name.ident().name, GenericParamDefKind::Lifetime { outlives })
 463             }
 464             hir::GenericParamKind::Type { ref default, synthetic } => (
 465                 self.name.ident().name,
 466                 GenericParamDefKind::Type {
 467                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
 468                     bounds: self.bounds.iter().filter_map(|x| x.clean(cx)).collect(),
 469                     default: default.map(|t| t.clean(cx)).map(Box::new),
 470                     synthetic,
 471                 },
 472             ),
 473             hir::GenericParamKind::Const { ref ty, default } => (
 474                 self.name.ident().name,
 475                 GenericParamDefKind::Const {
 476                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
 477                     ty: Box::new(ty.clean(cx)),
 478                     default: default.map(|ct| {
 479                         let def_id = cx.tcx.hir().local_def_id(ct.hir_id);
 480                         Box::new(ty::Const::from_anon_const(cx.tcx, def_id).to_string())
 481                     }),
 482                 },
 483             ),
 484         };
 485
 486         GenericParamDef { name, kind }
 487     }
 488 }
 489
 490 impl Clean<Generics> for hir::Generics<'_> {
 491     fn clean(&self, cx: &mut DocContext<'_>) -> Generics {
 492         // Synthetic type-parameters are inserted after normal ones.
 493         // In order for normal parameters to be able to refer to synthetic ones,
 494         // scans them first.
 495         fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
 496             match param.kind {
 497                 hir::GenericParamKind::Type { synthetic, .. } => synthetic,
 498                 _ => false,
 499             }
 500         }
 501         /// This can happen for `async fn`, e.g. `async fn f<'_>(&'_ self)`.
 502         ///
 503         /// See [`lifetime_to_generic_param`] in [`rustc_ast_lowering`] for more information.
 504         ///
 505         /// [`lifetime_to_generic_param`]: rustc_ast_lowering::LoweringContext::lifetime_to_generic_param
 506         fn is_elided_lifetime(param: &hir::GenericParam<'_>) -> bool {
 507             matches!(
 508                 param.kind,
 509                 hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided }
 510             )
 511         }
 512
 513         let impl_trait_params = self
 514             .params
 515             .iter()
 516             .filter(|param| is_impl_trait(param))
 517             .map(|param| {
 518                 let param: GenericParamDef = param.clean(cx);
 519                 match param.kind {
 520                     GenericParamDefKind::Lifetime { .. } => unreachable!(),
 521                     GenericParamDefKind::Type { did, ref bounds, .. } => {
 522                         cx.impl_trait_bounds.insert(did.into(), bounds.clone());
 523                     }
 524                     GenericParamDefKind::Const { .. } => unreachable!(),
 525                 }
 526                 param
 527             })
 528             .collect::<Vec<_>>();
 529
 530         let mut params = Vec::with_capacity(self.params.len());
 531         for p in self.params.iter().filter(|p| !is_impl_trait(p) && !is_elided_lifetime(p)) {
 532             let p = p.clean(cx);
 533             params.push(p);
 534         }
 535         params.extend(impl_trait_params);
 536
 537         let mut generics = Generics {
 538             params,
 539             where_predicates: self.where_clause.predicates.iter().map(|x| x.clean(cx)).collect(),
 540         };
 541
 542         // Some duplicates are generated for ?Sized bounds between type params and where
 543         // predicates. The point in here is to move the bounds definitions from type params
 544         // to where predicates when such cases occur.
 545         for where_pred in &mut generics.where_predicates {
 546             match *where_pred {
 547                 WherePredicate::BoundPredicate {
 548                     ty: Generic(ref name), ref mut bounds, ..
 549                 } => {
 550                     if bounds.is_empty() {
 551                         for param in &mut generics.params {
 552                             match param.kind {
 553                                 GenericParamDefKind::Lifetime { .. } => {}
 554                                 GenericParamDefKind::Type { bounds: ref mut ty_bounds, .. } => {
 555                                     if &param.name == name {
 556                                         mem::swap(bounds, ty_bounds);
 557                                         break;
 558                                     }
 559                                 }
 560                                 GenericParamDefKind::Const { .. } => {}
 561                             }
 562                         }
 563                     }
 564                 }
 565                 _ => continue,
 566             }
 567         }
 568         generics
 569     }
 570 }
 571
 572 fn clean_ty_generics(
 573     cx: &mut DocContext<'_>,
 574     gens: &ty::Generics,
 575     preds: ty::GenericPredicates<'_>,
 576 ) -> Generics {
 577     // Don't populate `cx.impl_trait_bounds` before `clean`ning `where` clauses,
 578     // since `Clean for ty::Predicate` would consume them.
 579     let mut impl_trait = BTreeMap::<ImplTraitParam, Vec<GenericBound>>::default();
 580
 581     // Bounds in the type_params and lifetimes fields are repeated in the
 582     // predicates field (see rustc_typeck::collect::ty_generics), so remove
 583     // them.
 584     let stripped_params = gens
 585         .params
 586         .iter()
 587         .filter_map(|param| match param.kind {
 588             ty::GenericParamDefKind::Lifetime => Some(param.clean(cx)),
 589             ty::GenericParamDefKind::Type { synthetic, .. } => {
 590                 if param.name == kw::SelfUpper {
 591                     assert_eq!(param.index, 0);
 592                     return None;
 593                 }
 594                 if synthetic {
 595                     impl_trait.insert(param.index.into(), vec![]);
 596                     return None;
 597                 }
 598                 Some(param.clean(cx))
 599             }
 600             ty::GenericParamDefKind::Const { .. } => Some(param.clean(cx)),
 601         })
 602         .collect::<Vec<GenericParamDef>>();
 603
 604     // param index -> [(DefId of trait, associated type name, type)]
 605     let mut impl_trait_proj = FxHashMap::<u32, Vec<(DefId, Symbol, Ty<'_>)>>::default();
 606
 607     let where_predicates = preds
 608         .predicates
 609         .iter()
 610         .flat_map(|(p, _)| {
 611             let mut projection = None;
 612             let param_idx = (|| {
 613                 let bound_p = p.kind();
 614                 match bound_p.skip_binder() {
 615                     ty::PredicateKind::Trait(pred) => {
 616                         if let ty::Param(param) = pred.self_ty().kind() {
 617                             return Some(param.index);
 618                         }
 619                     }
 620                     ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty, _reg)) => {
 621                         if let ty::Param(param) = ty.kind() {
 622                             return Some(param.index);
 623                         }
 624                     }
 625                     ty::PredicateKind::Projection(p) => {
 626                         if let ty::Param(param) = p.projection_ty.self_ty().kind() {
 627                             projection = Some(bound_p.rebind(p));
 628                             return Some(param.index);
 629                         }
 630                     }
 631                     _ => (),
 632                 }
 633
 634                 None
 635             })();
 636
 637             if let Some(param_idx) = param_idx {
 638                 if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
 639                     let p: WherePredicate = p.clean(cx)?;
 640
 641                     b.extend(
 642                         p.get_bounds()
 643                             .into_iter()
 644                             .flatten()
 645                             .cloned()
 646                             .filter(|b| !b.is_sized_bound(cx)),
 647                     );
 648
 649                     let proj = projection
 650                         .map(|p| (p.skip_binder().projection_ty.clean(cx), p.skip_binder().term));
 651                     if let Some(((_, trait_did, name), rhs)) =
 652                         proj.as_ref().and_then(|(lhs, rhs)| Some((lhs.projection()?, rhs)))
 653                     {
 654                         // FIXME(...): Remove this unwrap()
 655                         impl_trait_proj.entry(param_idx).or_default().push((
 656                             trait_did,
 657                             name,
 658                             rhs.ty().unwrap(),
 659                         ));
 660                     }
 661
 662                     return None;
 663                 }
 664             }
 665
 666             Some(p)
 667         })
 668         .collect::<Vec<_>>();
 669
 670     for (param, mut bounds) in impl_trait {
 671         // Move trait bounds to the front.
 672         bounds.sort_by_key(|b| !matches!(b, GenericBound::TraitBound(..)));
 673
 674         if let crate::core::ImplTraitParam::ParamIndex(idx) = param {
 675             if let Some(proj) = impl_trait_proj.remove(&idx) {
 676                 for (trait_did, name, rhs) in proj {
 677                     let rhs = rhs.clean(cx);
 678                     simplify::merge_bounds(cx, &mut bounds, trait_did, name, &Term::Type(rhs));
 679                 }
 680             }
 681         } else {
 682             unreachable!();
 683         }
 684
 685         cx.impl_trait_bounds.insert(param, bounds);
 686     }
 687
 688     // Now that `cx.impl_trait_bounds` is populated, we can process
 689     // remaining predicates which could contain `impl Trait`.
 690     let mut where_predicates =
 691         where_predicates.into_iter().flat_map(|p| p.clean(cx)).collect::<Vec<_>>();
 692
 693     // Type parameters have a Sized bound by default unless removed with
 694     // ?Sized. Scan through the predicates and mark any type parameter with
 695     // a Sized bound, removing the bounds as we find them.
 696     //
 697     // Note that associated types also have a sized bound by default, but we
 698     // don't actually know the set of associated types right here so that's
 699     // handled in cleaning associated types
 700     let mut sized_params = FxHashSet::default();
 701     where_predicates.retain(|pred| match *pred {
 702         WherePredicate::BoundPredicate { ty: Generic(ref g), ref bounds, .. } => {
 703             if bounds.iter().any(|b| b.is_sized_bound(cx)) {
 704                 sized_params.insert(*g);
 705                 false
 706             } else {
 707                 true
 708             }
 709         }
 710         _ => true,
 711     });
 712
 713     // Run through the type parameters again and insert a ?Sized
 714     // unbound for any we didn't find to be Sized.
 715     for tp in &stripped_params {
 716         if matches!(tp.kind, types::GenericParamDefKind::Type { .. })
 717             && !sized_params.contains(&tp.name)
 718         {
 719             where_predicates.push(WherePredicate::BoundPredicate {
 720                 ty: Type::Generic(tp.name),
 721                 bounds: vec![GenericBound::maybe_sized(cx)],
 722                 bound_params: Vec::new(),
 723             })
 724         }
 725     }
 726
 727     // It would be nice to collect all of the bounds on a type and recombine
 728     // them if possible, to avoid e.g., `where T: Foo, T: Bar, T: Sized, T: 'a`
 729     // and instead see `where T: Foo + Bar + Sized + 'a`
 730
 731     Generics {
 732         params: stripped_params,
 733         where_predicates: simplify::where_clauses(cx, where_predicates),
 734     }
 735 }
 736
 737 fn clean_fn_or_proc_macro(
 738     item: &hir::Item<'_>,
 739     sig: &hir::FnSig<'_>,
 740     generics: &hir::Generics<'_>,
 741     body_id: hir::BodyId,
 742     name: &mut Symbol,
 743     cx: &mut DocContext<'_>,
 744 ) -> ItemKind {
 745     let attrs = cx.tcx.hir().attrs(item.hir_id());
 746     let macro_kind = attrs.iter().find_map(|a| {
 747         if a.has_name(sym::proc_macro) {
 748             Some(MacroKind::Bang)
 749         } else if a.has_name(sym::proc_macro_derive) {
 750             Some(MacroKind::Derive)
 751         } else if a.has_name(sym::proc_macro_attribute) {
 752             Some(MacroKind::Attr)
 753         } else {
 754             None
 755         }
 756     });
 757     match macro_kind {
 758         Some(kind) => {
 759             if kind == MacroKind::Derive {
 760                 *name = attrs
 761                     .lists(sym::proc_macro_derive)
 762                     .find_map(|mi| mi.ident())
 763                     .expect("proc-macro derives require a name")
 764                     .name;
 765             }
 766
 767             let mut helpers = Vec::new();
 768             for mi in attrs.lists(sym::proc_macro_derive) {
 769                 if !mi.has_name(sym::attributes) {
 770                     continue;
 771                 }
 772
 773                 if let Some(list) = mi.meta_item_list() {
 774                     for inner_mi in list {
 775                         if let Some(ident) = inner_mi.ident() {
 776                             helpers.push(ident.name);
 777                         }
 778                     }
 779                 }
 780             }
 781             ProcMacroItem(ProcMacro { kind, helpers })
 782         }
 783         None => {
 784             let mut func = clean_function(cx, sig, generics, body_id);
 785             let def_id = item.def_id.to_def_id();
 786             func.header.constness =
 787                 if cx.tcx.is_const_fn(def_id) && is_unstable_const_fn(cx.tcx, def_id).is_none() {
 788                     hir::Constness::Const
 789                 } else {
 790                     hir::Constness::NotConst
 791                 };
 792             clean_fn_decl_legacy_const_generics(&mut func, attrs);
 793             FunctionItem(func)
 794         }
 795     }
 796 }
 797
 798 /// This is needed to make it more "readable" when documenting functions using
 799 /// `rustc_legacy_const_generics`. More information in
 800 /// <https://github.com/rust-lang/rust/issues/83167>.
 801 fn clean_fn_decl_legacy_const_generics(func: &mut Function, attrs: &[ast::Attribute]) {
 802     for meta_item_list in attrs
 803         .iter()
 804         .filter(|a| a.has_name(sym::rustc_legacy_const_generics))
 805         .filter_map(|a| a.meta_item_list())
 806     {
 807         for (pos, literal) in meta_item_list.iter().filter_map(|meta| meta.literal()).enumerate() {
 808             match literal.kind {
 809                 ast::LitKind::Int(a, _) => {
 810                     let gen = func.generics.params.remove(0);
 811                     if let GenericParamDef { name, kind: GenericParamDefKind::Const { ty, .. } } =
 812                         gen
 813                     {
 814                         func.decl
 815                             .inputs
 816                             .values
 817                             .insert(a as _, Argument { name, type_: *ty, is_const: true });
 818                     } else {
 819                         panic!("unexpected non const in position {}", pos);
 820                     }
 821                 }
 822                 _ => panic!("invalid arg index"),
 823             }
 824         }
 825     }
 826 }
 827
 828 fn clean_function(
 829     cx: &mut DocContext<'_>,
 830     sig: &hir::FnSig<'_>,
 831     generics: &hir::Generics<'_>,
 832     body_id: hir::BodyId,
 833 ) -> Function {
 834     let (generics, decl) = enter_impl_trait(cx, |cx| {
 835         // NOTE: generics must be cleaned before args
 836         let generics = generics.clean(cx);
 837         let args = clean_args_from_types_and_body_id(cx, sig.decl.inputs, body_id);
 838         let decl = clean_fn_decl_with_args(cx, sig.decl, args);
 839         (generics, decl)
 840     });
 841     Function { decl, generics, header: sig.header }
 842 }
 843
 844 fn clean_args_from_types_and_names(
 845     cx: &mut DocContext<'_>,
 846     types: &[hir::Ty<'_>],
 847     names: &[Ident],
 848 ) -> Arguments {
 849     Arguments {
 850         values: types
 851             .iter()
 852             .enumerate()
 853             .map(|(i, ty)| {
 854                 let mut name = names.get(i).map_or(kw::Empty, |ident| ident.name);
 855                 if name.is_empty() {
 856                     name = kw::Underscore;
 857                 }
 858                 Argument { name, type_: ty.clean(cx), is_const: false }
 859             })
 860             .collect(),
 861     }
 862 }
 863
 864 fn clean_args_from_types_and_body_id(
 865     cx: &mut DocContext<'_>,
 866     types: &[hir::Ty<'_>],
 867     body_id: hir::BodyId,
 868 ) -> Arguments {
 869     let body = cx.tcx.hir().body(body_id);
 870
 871     Arguments {
 872         values: types
 873             .iter()
 874             .enumerate()
 875             .map(|(i, ty)| Argument {
 876                 name: name_from_pat(body.params[i].pat),
 877                 type_: ty.clean(cx),
 878                 is_const: false,
 879             })
 880             .collect(),
 881     }
 882 }
 883
 884 fn clean_fn_decl_with_args(
 885     cx: &mut DocContext<'_>,
 886     decl: &hir::FnDecl<'_>,
 887     args: Arguments,
 888 ) -> FnDecl {
 889     FnDecl { inputs: args, output: decl.output.clean(cx), c_variadic: decl.c_variadic }
 890 }
 891
 892 fn clean_fn_decl_from_did_and_sig(
 893     cx: &mut DocContext<'_>,
 894     did: Option<DefId>,
 895     sig: ty::PolyFnSig<'_>,
 896 ) -> FnDecl {
 897     let mut names = did.map_or(&[] as &[_], |did| cx.tcx.fn_arg_names(did)).iter();
 898
 899     // We assume all empty tuples are default return type. This theoretically can discard `-> ()`,
 900     // but shouldn't change any code meaning.
 901     let output = match sig.skip_binder().output().clean(cx) {
 902         Type::Tuple(inner) if inner.len() == 0 => DefaultReturn,
 903         ty => Return(ty),
 904     };
 905
 906     FnDecl {
 907         output,
 908         c_variadic: sig.skip_binder().c_variadic,
 909         inputs: Arguments {
 910             values: sig
 911                 .skip_binder()
 912                 .inputs()
 913                 .iter()
 914                 .map(|t| Argument {
 915                     type_: t.clean(cx),
 916                     name: names.next().map_or(kw::Empty, |i| i.name),
 917                     is_const: false,
 918                 })
 919                 .collect(),
 920         },
 921     }
 922 }
 923
 924 impl Clean<FnRetTy> for hir::FnRetTy<'_> {
 925     fn clean(&self, cx: &mut DocContext<'_>) -> FnRetTy {
 926         match *self {
 927             Self::Return(ref typ) => Return(typ.clean(cx)),
 928             Self::DefaultReturn(..) => DefaultReturn,
 929         }
 930     }
 931 }
 932
 933 impl Clean<bool> for hir::IsAuto {
 934     fn clean(&self, _: &mut DocContext<'_>) -> bool {
 935         match *self {
 936             hir::IsAuto::Yes => true,
 937             hir::IsAuto::No => false,
 938         }
 939     }
 940 }
 941
 942 impl Clean<Path> for hir::TraitRef<'_> {
 943     fn clean(&self, cx: &mut DocContext<'_>) -> Path {
 944         let path = self.path.clean(cx);
 945         register_res(cx, path.res);
 946         path
 947     }
 948 }
 949
 950 impl Clean<PolyTrait> for hir::PolyTraitRef<'_> {
 951     fn clean(&self, cx: &mut DocContext<'_>) -> PolyTrait {
 952         PolyTrait {
 953             trait_: self.trait_ref.clean(cx),
 954             generic_params: self.bound_generic_params.iter().map(|x| x.clean(cx)).collect(),
 955         }
 956     }
 957 }
 958
 959 impl Clean<Item> for hir::TraitItem<'_> {
 960     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
 961         let local_did = self.def_id.to_def_id();
 962         cx.with_param_env(local_did, |cx| {
 963             let inner = match self.kind {
 964                 hir::TraitItemKind::Const(ref ty, default) => {
 965                     let default =
 966                         default.map(|e| ConstantKind::Local { def_id: local_did, body: e });
 967                     AssocConstItem(ty.clean(cx), default)
 968                 }
 969                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
 970                     let mut m = clean_function(cx, sig, &self.generics, body);
 971                     if m.header.constness == hir::Constness::Const
 972                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
 973                     {
 974                         m.header.constness = hir::Constness::NotConst;
 975                     }
 976                     MethodItem(m, None)
 977                 }
 978                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(names)) => {
 979                     let (generics, decl) = enter_impl_trait(cx, |cx| {
 980                         // NOTE: generics must be cleaned before args
 981                         let generics = self.generics.clean(cx);
 982                         let args = clean_args_from_types_and_names(cx, sig.decl.inputs, names);
 983                         let decl = clean_fn_decl_with_args(cx, sig.decl, args);
 984                         (generics, decl)
 985                     });
 986                     let mut t = Function { header: sig.header, decl, generics };
 987                     if t.header.constness == hir::Constness::Const
 988                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
 989                     {
 990                         t.header.constness = hir::Constness::NotConst;
 991                     }
 992                     TyMethodItem(t)
 993                 }
 994                 hir::TraitItemKind::Type(bounds, ref default) => {
 995                     let bounds = bounds.iter().filter_map(|x| x.clean(cx)).collect();
 996                     let default = default.map(|t| t.clean(cx));
 997                     AssocTypeItem(bounds, default)
 998                 }
 999             };
1000             let what_rustc_thinks =
1001                 Item::from_def_id_and_parts(local_did, Some(self.ident.name), inner, cx);
1002             // Trait items always inherit the trait's visibility -- we don't want to show `pub`.
1003             Item { visibility: Inherited, ..what_rustc_thinks }
1004         })
1005     }
1006 }
1007
1008 impl Clean<Item> for hir::ImplItem<'_> {
1009     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1010         let local_did = self.def_id.to_def_id();
1011         cx.with_param_env(local_did, |cx| {
1012             let inner = match self.kind {
1013                 hir::ImplItemKind::Const(ref ty, expr) => {
1014                     let default = Some(ConstantKind::Local { def_id: local_did, body: expr });
1015                     AssocConstItem(ty.clean(cx), default)
1016                 }
1017                 hir::ImplItemKind::Fn(ref sig, body) => {
1018                     let mut m = clean_function(cx, sig, &self.generics, body);
1019                     if m.header.constness == hir::Constness::Const
1020                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
1021                     {
1022                         m.header.constness = hir::Constness::NotConst;
1023                     }
1024                     let defaultness = cx.tcx.associated_item(self.def_id).defaultness;
1025                     MethodItem(m, Some(defaultness))
1026                 }
1027                 hir::ImplItemKind::TyAlias(ref hir_ty) => {
1028                     let type_ = hir_ty.clean(cx);
1029                     let item_type = hir_ty_to_ty(cx.tcx, hir_ty).clean(cx);
1030                     TypedefItem(
1031                         Typedef {
1032                             type_,
1033                             generics: Generics::default(),
1034                             item_type: Some(item_type),
1035                         },
1036                         true,
1037                     )
1038                 }
1039             };
1040
1041             let mut what_rustc_thinks =
1042                 Item::from_def_id_and_parts(local_did, Some(self.ident.name), inner, cx);
1043
1044             let impl_ref = cx.tcx.parent(local_did).and_then(|did| cx.tcx.impl_trait_ref(did));
1045
1046             // Trait impl items always inherit the impl's visibility --
1047             // we don't want to show `pub`.
1048             if impl_ref.is_some() {
1049                 what_rustc_thinks.visibility = Inherited;
1050             }
1051
1052             what_rustc_thinks
1053         })
1054     }
1055 }
1056
1057 impl Clean<Item> for ty::AssocItem {
1058     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1059         let tcx = cx.tcx;
1060         let kind = match self.kind {
1061             ty::AssocKind::Const => {
1062                 let ty = tcx.type_of(self.def_id);
1063                 let default = if self.defaultness.has_value() {
1064                     Some(ConstantKind::Extern { def_id: self.def_id })
1065                 } else {
1066                     None
1067                 };
1068                 AssocConstItem(ty.clean(cx), default)
1069             }
1070             ty::AssocKind::Fn => {
1071                 let generics = clean_ty_generics(
1072                     cx,
1073                     tcx.generics_of(self.def_id),
1074                     tcx.explicit_predicates_of(self.def_id),
1075                 );
1076                 let sig = tcx.fn_sig(self.def_id);
1077                 let mut decl = clean_fn_decl_from_did_and_sig(cx, Some(self.def_id), sig);
1078
1079                 if self.fn_has_self_parameter {
1080                     let self_ty = match self.container {
1081                         ty::ImplContainer(def_id) => tcx.type_of(def_id),
1082                         ty::TraitContainer(_) => tcx.types.self_param,
1083                     };
1084                     let self_arg_ty = sig.input(0).skip_binder();
1085                     if self_arg_ty == self_ty {
1086                         decl.inputs.values[0].type_ = Generic(kw::SelfUpper);
1087                     } else if let ty::Ref(_, ty, _) = *self_arg_ty.kind() {
1088                         if ty == self_ty {
1089                             match decl.inputs.values[0].type_ {
1090                                 BorrowedRef { ref mut type_, .. } => {
1091                                     **type_ = Generic(kw::SelfUpper)
1092                                 }
1093                                 _ => unreachable!(),
1094                             }
1095                         }
1096                     }
1097                 }
1098
1099                 let provided = match self.container {
1100                     ty::ImplContainer(_) => true,
1101                     ty::TraitContainer(_) => self.defaultness.has_value(),
1102                 };
1103                 if provided {
1104                     let constness = if tcx.is_const_fn_raw(self.def_id) {
1105                         hir::Constness::Const
1106                     } else {
1107                         hir::Constness::NotConst
1108                     };
1109                     let asyncness = tcx.asyncness(self.def_id);
1110                     let defaultness = match self.container {
1111                         ty::ImplContainer(_) => Some(self.defaultness),
1112                         ty::TraitContainer(_) => None,
1113                     };
1114                     MethodItem(
1115                         Function {
1116                             generics,
1117                             decl,
1118                             header: hir::FnHeader {
1119                                 unsafety: sig.unsafety(),
1120                                 abi: sig.abi(),
1121                                 constness,
1122                                 asyncness,
1123                             },
1124                         },
1125                         defaultness,
1126                     )
1127                 } else {
1128                     TyMethodItem(Function {
1129                         generics,
1130                         decl,
1131                         header: hir::FnHeader {
1132                             unsafety: sig.unsafety(),
1133                             abi: sig.abi(),
1134                             constness: hir::Constness::NotConst,
1135                             asyncness: hir::IsAsync::NotAsync,
1136                         },
1137                     })
1138                 }
1139             }
1140             ty::AssocKind::Type => {
1141                 let my_name = self.name;
1142
1143                 if let ty::TraitContainer(_) = self.container {
1144                     let bounds = tcx.explicit_item_bounds(self.def_id);
1145                     let predicates = ty::GenericPredicates { parent: None, predicates: bounds };
1146                     let generics = clean_ty_generics(cx, tcx.generics_of(self.def_id), predicates);
1147                     let mut bounds = generics
1148                         .where_predicates
1149                         .iter()
1150                         .filter_map(|pred| {
1151                             let (name, self_type, trait_, bounds) = match *pred {
1152                                 WherePredicate::BoundPredicate {
1153                                     ty: QPath { ref name, ref self_type, ref trait_, .. },
1154                                     ref bounds,
1155                                     ..
1156                                 } => (name, self_type, trait_, bounds),
1157                                 _ => return None,
1158                             };
1159                             if *name != my_name {
1160                                 return None;
1161                             }
1162                             if trait_.def_id() != self.container.id() {
1163                                 return None;
1164                             }
1165                             match **self_type {
1166                                 Generic(ref s) if *s == kw::SelfUpper => {}
1167                                 _ => return None,
1168                             }
1169                             Some(bounds)
1170                         })
1171                         .flat_map(|i| i.iter().cloned())
1172                         .collect::<Vec<_>>();
1173                     // Our Sized/?Sized bound didn't get handled when creating the generics
1174                     // because we didn't actually get our whole set of bounds until just now
1175                     // (some of them may have come from the trait). If we do have a sized
1176                     // bound, we remove it, and if we don't then we add the `?Sized` bound
1177                     // at the end.
1178                     match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1179                         Some(i) => {
1180                             bounds.remove(i);
1181                         }
1182                         None => bounds.push(GenericBound::maybe_sized(cx)),
1183                     }
1184
1185                     let ty = if self.defaultness.has_value() {
1186                         Some(tcx.type_of(self.def_id))
1187                     } else {
1188                         None
1189                     };
1190
1191                     AssocTypeItem(bounds, ty.map(|t| t.clean(cx)))
1192                 } else {
1193                     // FIXME: when could this happen? Associated items in inherent impls?
1194                     let type_ = tcx.type_of(self.def_id).clean(cx);
1195                     TypedefItem(
1196                         Typedef {
1197                             type_,
1198                             generics: Generics { params: Vec::new(), where_predicates: Vec::new() },
1199                             item_type: None,
1200                         },
1201                         true,
1202                     )
1203                 }
1204             }
1205         };
1206
1207         let mut what_rustc_thinks =
1208             Item::from_def_id_and_parts(self.def_id, Some(self.name), kind, cx);
1209
1210         let impl_ref = tcx.parent(self.def_id).and_then(|did| tcx.impl_trait_ref(did));
1211
1212         // Trait impl items always inherit the impl's visibility --
1213         // we don't want to show `pub`.
1214         if impl_ref.is_some() {
1215             what_rustc_thinks.visibility = Visibility::Inherited;
1216         }
1217
1218         what_rustc_thinks
1219     }
1220 }
1221
1222 fn clean_qpath(hir_ty: &hir::Ty<'_>, cx: &mut DocContext<'_>) -> Type {
1223     let hir::Ty { hir_id: _, span, ref kind } = *hir_ty;
1224     let qpath = match kind {
1225         hir::TyKind::Path(qpath) => qpath,
1226         _ => unreachable!(),
1227     };
1228
1229     match qpath {
1230         hir::QPath::Resolved(None, ref path) => {
1231             if let Res::Def(DefKind::TyParam, did) = path.res {
1232                 if let Some(new_ty) = cx.substs.get(&did).and_then(|p| p.as_ty()).cloned() {
1233                     return new_ty;
1234                 }
1235                 if let Some(bounds) = cx.impl_trait_bounds.remove(&did.into()) {
1236                     return ImplTrait(bounds);
1237                 }
1238             }
1239
1240             if let Some(expanded) = maybe_expand_private_type_alias(cx, path) {
1241                 expanded
1242             } else {
1243                 let path = path.clean(cx);
1244                 resolve_type(cx, path)
1245             }
1246         }
1247         hir::QPath::Resolved(Some(ref qself), p) => {
1248             // Try to normalize `<X as Y>::T` to a type
1249             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1250             if let Some(normalized_value) = normalize(cx, ty) {
1251                 return normalized_value.clean(cx);
1252             }
1253
1254             let trait_segments = &p.segments[..p.segments.len() - 1];
1255             let trait_def = cx.tcx.associated_item(p.res.def_id()).container.id();
1256             let trait_ = self::Path {
1257                 res: Res::Def(DefKind::Trait, trait_def),
1258                 segments: trait_segments.iter().map(|x| x.clean(cx)).collect(),
1259             };
1260             register_res(cx, trait_.res);
1261             Type::QPath {
1262                 name: p.segments.last().expect("segments were empty").ident.name,
1263                 self_def_id: Some(DefId::local(qself.hir_id.owner.local_def_index)),
1264                 self_type: box qself.clean(cx),
1265                 trait_,
1266             }
1267         }
1268         hir::QPath::TypeRelative(ref qself, segment) => {
1269             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1270             let res = match ty.kind() {
1271                 ty::Projection(proj) => Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id),
1272                 // Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
1273                 ty::Error(_) => return Type::Infer,
1274                 _ => bug!("clean: expected associated type, found `{:?}`", ty),
1275             };
1276             let trait_ = hir::Path { span, res, segments: &[] }.clean(cx);
1277             register_res(cx, trait_.res);
1278             Type::QPath {
1279                 name: segment.ident.name,
1280                 self_def_id: res.opt_def_id(),
1281                 self_type: box qself.clean(cx),
1282                 trait_,
1283             }
1284         }
1285         hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1286     }
1287 }
1288
1289 fn maybe_expand_private_type_alias(cx: &mut DocContext<'_>, path: &hir::Path<'_>) -> Option<Type> {
1290     let Res::Def(DefKind::TyAlias, def_id) = path.res else { return None };
1291     // Substitute private type aliases
1292     let Some(def_id) = def_id.as_local() else { return None };
1293     let alias = if !cx.cache.access_levels.is_exported(def_id.to_def_id()) {
1294         &cx.tcx.hir().expect_item(def_id).kind
1295     } else {
1296         return None;
1297     };
1298     let hir::ItemKind::TyAlias(ty, generics) = alias else { return None };
1299
1300     let provided_params = &path.segments.last().expect("segments were empty");
1301     let mut substs = FxHashMap::default();
1302     let generic_args = provided_params.args();
1303
1304     let mut indices: hir::GenericParamCount = Default::default();
1305     for param in generics.params.iter() {
1306         match param.kind {
1307             hir::GenericParamKind::Lifetime { .. } => {
1308                 let mut j = 0;
1309                 let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1310                     hir::GenericArg::Lifetime(lt) => {
1311                         if indices.lifetimes == j {
1312                             return Some(lt);
1313                         }
1314                         j += 1;
1315                         None
1316                     }
1317                     _ => None,
1318                 });
1319                 if let Some(lt) = lifetime.cloned() {
1320                     let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1321                     let cleaned = if !lt.is_elided() {
1322                         lt.clean(cx)
1323                     } else {
1324                         self::types::Lifetime::elided()
1325                     };
1326                     substs.insert(lt_def_id.to_def_id(), SubstParam::Lifetime(cleaned));
1327                 }
1328                 indices.lifetimes += 1;
1329             }
1330             hir::GenericParamKind::Type { ref default, .. } => {
1331                 let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1332                 let mut j = 0;
1333                 let type_ = generic_args.args.iter().find_map(|arg| match arg {
1334                     hir::GenericArg::Type(ty) => {
1335                         if indices.types == j {
1336                             return Some(ty);
1337                         }
1338                         j += 1;
1339                         None
1340                     }
1341                     _ => None,
1342                 });
1343                 if let Some(ty) = type_ {
1344                     substs.insert(ty_param_def_id.to_def_id(), SubstParam::Type(ty.clean(cx)));
1345                 } else if let Some(default) = *default {
1346                     substs.insert(ty_param_def_id.to_def_id(), SubstParam::Type(default.clean(cx)));
1347                 }
1348                 indices.types += 1;
1349             }
1350             hir::GenericParamKind::Const { .. } => {
1351                 let const_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1352                 let mut j = 0;
1353                 let const_ = generic_args.args.iter().find_map(|arg| match arg {
1354                     hir::GenericArg::Const(ct) => {
1355                         if indices.consts == j {
1356                             return Some(ct);
1357                         }
1358                         j += 1;
1359                         None
1360                     }
1361                     _ => None,
1362                 });
1363                 if let Some(ct) = const_ {
1364                     substs
1365                         .insert(const_param_def_id.to_def_id(), SubstParam::Constant(ct.clean(cx)));
1366                 }
1367                 // FIXME(const_generics_defaults)
1368                 indices.consts += 1;
1369             }
1370         }
1371     }
1372
1373     Some(cx.enter_alias(substs, |cx| ty.clean(cx)))
1374 }
1375
1376 impl Clean<Type> for hir::Ty<'_> {
1377     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
1378         use rustc_hir::*;
1379
1380         match self.kind {
1381             TyKind::Never => Primitive(PrimitiveType::Never),
1382             TyKind::Ptr(ref m) => RawPointer(m.mutbl, box m.ty.clean(cx)),
1383             TyKind::Rptr(ref l, ref m) => {
1384                 // There are two times a `Fresh` lifetime can be created:
1385                 // 1. For `&'_ x`, written by the user. This corresponds to `lower_lifetime` in `rustc_ast_lowering`.
1386                 // 2. For `&x` as a parameter to an `async fn`. This corresponds to `elided_ref_lifetime in `rustc_ast_lowering`.
1387                 //    See #59286 for more information.
1388                 // Ideally we would only hide the `'_` for case 2., but I don't know a way to distinguish it.
1389                 // Turning `fn f(&'_ self)` into `fn f(&self)` isn't the worst thing in the world, though;
1390                 // there's no case where it could cause the function to fail to compile.
1391                 let elided =
1392                     l.is_elided() || matches!(l.name, LifetimeName::Param(ParamName::Fresh(_)));
1393                 let lifetime = if elided { None } else { Some(l.clean(cx)) };
1394                 BorrowedRef { lifetime, mutability: m.mutbl, type_: box m.ty.clean(cx) }
1395             }
1396             TyKind::Slice(ref ty) => Slice(box ty.clean(cx)),
1397             TyKind::Array(ref ty, ref length) => {
1398                 let length = match length {
1399                     hir::ArrayLen::Infer(_, _) => "_".to_string(),
1400                     hir::ArrayLen::Body(anon_const) => {
1401                         let def_id = cx.tcx.hir().local_def_id(anon_const.hir_id);
1402                         // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1403                         // as we currently do not supply the parent generics to anonymous constants
1404                         // but do allow `ConstKind::Param`.
1405                         //
1406                         // `const_eval_poly` tries to to first substitute generic parameters which
1407                         // results in an ICE while manually constructing the constant and using `eval`
1408                         // does nothing for `ConstKind::Param`.
1409                         let ct = ty::Const::from_anon_const(cx.tcx, def_id);
1410                         let param_env = cx.tcx.param_env(def_id);
1411                         print_const(cx, ct.eval(cx.tcx, param_env))
1412                     }
1413                 };
1414
1415                 Array(box ty.clean(cx), length)
1416             }
1417             TyKind::Tup(tys) => Tuple(tys.iter().map(|x| x.clean(cx)).collect()),
1418             TyKind::OpaqueDef(item_id, _) => {
1419                 let item = cx.tcx.hir().item(item_id);
1420                 if let hir::ItemKind::OpaqueTy(ref ty) = item.kind {
1421                     ImplTrait(ty.bounds.iter().filter_map(|x| x.clean(cx)).collect())
1422                 } else {
1423                     unreachable!()
1424                 }
1425             }
1426             TyKind::Path(_) => clean_qpath(self, cx),
1427             TyKind::TraitObject(bounds, ref lifetime, _) => {
1428                 let bounds = bounds.iter().map(|bound| bound.clean(cx)).collect();
1429                 let lifetime = if !lifetime.is_elided() { Some(lifetime.clean(cx)) } else { None };
1430                 DynTrait(bounds, lifetime)
1431             }
1432             TyKind::BareFn(ref barefn) => BareFunction(box barefn.clean(cx)),
1433             // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
1434             TyKind::Infer | TyKind::Err => Infer,
1435             TyKind::Typeof(..) => panic!("unimplemented type {:?}", self.kind),
1436         }
1437     }
1438 }
1439
1440 /// Returns `None` if the type could not be normalized
1441 fn normalize<'tcx>(cx: &mut DocContext<'tcx>, ty: Ty<'_>) -> Option<Ty<'tcx>> {
1442     // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1443     if !cx.tcx.sess.opts.debugging_opts.normalize_docs {
1444         return None;
1445     }
1446
1447     use crate::rustc_trait_selection::infer::TyCtxtInferExt;
1448     use crate::rustc_trait_selection::traits::query::normalize::AtExt;
1449     use rustc_middle::traits::ObligationCause;
1450
1451     // Try to normalize `<X as Y>::T` to a type
1452     let lifted = ty.lift_to_tcx(cx.tcx).unwrap();
1453     let normalized = cx.tcx.infer_ctxt().enter(|infcx| {
1454         infcx
1455             .at(&ObligationCause::dummy(), cx.param_env)
1456             .normalize(lifted)
1457             .map(|resolved| infcx.resolve_vars_if_possible(resolved.value))
1458     });
1459     match normalized {
1460         Ok(normalized_value) => {
1461             debug!("normalized {:?} to {:?}", ty, normalized_value);
1462             Some(normalized_value)
1463         }
1464         Err(err) => {
1465             debug!("failed to normalize {:?}: {:?}", ty, err);
1466             None
1467         }
1468     }
1469 }
1470
1471 impl<'tcx> Clean<Type> for Ty<'tcx> {
1472     fn clean(&self, cx: &mut DocContext<'_>) -> Type {
1473         trace!("cleaning type: {:?}", self);
1474         let ty = normalize(cx, *self).unwrap_or(*self);
1475         match *ty.kind() {
1476             ty::Never => Primitive(PrimitiveType::Never),
1477             ty::Bool => Primitive(PrimitiveType::Bool),
1478             ty::Char => Primitive(PrimitiveType::Char),
1479             ty::Int(int_ty) => Primitive(int_ty.into()),
1480             ty::Uint(uint_ty) => Primitive(uint_ty.into()),
1481             ty::Float(float_ty) => Primitive(float_ty.into()),
1482             ty::Str => Primitive(PrimitiveType::Str),
1483             ty::Slice(ty) => Slice(box ty.clean(cx)),
1484             ty::Array(ty, n) => {
1485                 let mut n = cx.tcx.lift(n).expect("array lift failed");
1486                 n = n.eval(cx.tcx, ty::ParamEnv::reveal_all());
1487                 let n = print_const(cx, n);
1488                 Array(box ty.clean(cx), n)
1489             }
1490             ty::RawPtr(mt) => RawPointer(mt.mutbl, box mt.ty.clean(cx)),
1491             ty::Ref(r, ty, mutbl) => {
1492                 BorrowedRef { lifetime: r.clean(cx), mutability: mutbl, type_: box ty.clean(cx) }
1493             }
1494             ty::FnDef(..) | ty::FnPtr(_) => {
1495                 let ty = cx.tcx.lift(*self).expect("FnPtr lift failed");
1496                 let sig = ty.fn_sig(cx.tcx);
1497                 let decl = clean_fn_decl_from_did_and_sig(cx, None, sig);
1498                 BareFunction(box BareFunctionDecl {
1499                     unsafety: sig.unsafety(),
1500                     generic_params: Vec::new(),
1501                     decl,
1502                     abi: sig.abi(),
1503                 })
1504             }
1505             ty::Adt(def, substs) => {
1506                 let did = def.did;
1507                 let kind = match def.adt_kind() {
1508                     AdtKind::Struct => ItemType::Struct,
1509                     AdtKind::Union => ItemType::Union,
1510                     AdtKind::Enum => ItemType::Enum,
1511                 };
1512                 inline::record_extern_fqn(cx, did, kind);
1513                 let path = external_path(cx, did, false, vec![], substs);
1514                 Type::Path { path }
1515             }
1516             ty::Foreign(did) => {
1517                 inline::record_extern_fqn(cx, did, ItemType::ForeignType);
1518                 let path = external_path(cx, did, false, vec![], InternalSubsts::empty());
1519                 Type::Path { path }
1520             }
1521             ty::Dynamic(obj, ref reg) => {
1522                 // HACK: pick the first `did` as the `did` of the trait object. Someone
1523                 // might want to implement "native" support for marker-trait-only
1524                 // trait objects.
1525                 let mut dids = obj.principal_def_id().into_iter().chain(obj.auto_traits());
1526                 let did = dids
1527                     .next()
1528                     .unwrap_or_else(|| panic!("found trait object `{:?}` with no traits?", self));
1529                 let substs = match obj.principal() {
1530                     Some(principal) => principal.skip_binder().substs,
1531                     // marker traits have no substs.
1532                     _ => cx.tcx.intern_substs(&[]),
1533                 };
1534
1535                 inline::record_extern_fqn(cx, did, ItemType::Trait);
1536
1537                 let lifetime = reg.clean(cx);
1538                 let mut bounds = vec![];
1539
1540                 for did in dids {
1541                     let empty = cx.tcx.intern_substs(&[]);
1542                     let path = external_path(cx, did, false, vec![], empty);
1543                     inline::record_extern_fqn(cx, did, ItemType::Trait);
1544                     let bound = PolyTrait { trait_: path, generic_params: Vec::new() };
1545                     bounds.push(bound);
1546                 }
1547
1548                 let mut bindings = vec![];
1549                 for pb in obj.projection_bounds() {
1550                     bindings.push(TypeBinding {
1551                         name: cx.tcx.associated_item(pb.item_def_id()).name,
1552                         kind: TypeBindingKind::Equality { term: pb.skip_binder().term.clean(cx) },
1553                     });
1554                 }
1555
1556                 let path = external_path(cx, did, false, bindings, substs);
1557                 bounds.insert(0, PolyTrait { trait_: path, generic_params: Vec::new() });
1558
1559                 DynTrait(bounds, lifetime)
1560             }
1561             ty::Tuple(t) => Tuple(t.iter().map(|t| t.clean(cx)).collect()),
1562
1563             ty::Projection(ref data) => data.clean(cx),
1564
1565             ty::Param(ref p) => {
1566                 if let Some(bounds) = cx.impl_trait_bounds.remove(&p.index.into()) {
1567                     ImplTrait(bounds)
1568                 } else {
1569                     Generic(p.name)
1570                 }
1571             }
1572
1573             ty::Opaque(def_id, substs) => {
1574                 // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1575                 // by looking up the bounds associated with the def_id.
1576                 let substs = cx.tcx.lift(substs).expect("Opaque lift failed");
1577                 let bounds = cx
1578                     .tcx
1579                     .explicit_item_bounds(def_id)
1580                     .iter()
1581                     .map(|(bound, _)| bound.subst(cx.tcx, substs))
1582                     .collect::<Vec<_>>();
1583                 let mut regions = vec![];
1584                 let mut has_sized = false;
1585                 let mut bounds = bounds
1586                     .iter()
1587                     .filter_map(|bound| {
1588                         let bound_predicate = bound.kind();
1589                         let trait_ref = match bound_predicate.skip_binder() {
1590                             ty::PredicateKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
1591                             ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
1592                                 if let Some(r) = reg.clean(cx) {
1593                                     regions.push(GenericBound::Outlives(r));
1594                                 }
1595                                 return None;
1596                             }
1597                             _ => return None,
1598                         };
1599
1600                         if let Some(sized) = cx.tcx.lang_items().sized_trait() {
1601                             if trait_ref.def_id() == sized {
1602                                 has_sized = true;
1603                                 return None;
1604                             }
1605                         }
1606
1607                         let bindings: Vec<_> = bounds
1608                             .iter()
1609                             .filter_map(|bound| {
1610                                 if let ty::PredicateKind::Projection(proj) =
1611                                     bound.kind().skip_binder()
1612                                 {
1613                                     if proj.projection_ty.trait_ref(cx.tcx)
1614                                         == trait_ref.skip_binder()
1615                                     {
1616                                         Some(TypeBinding {
1617                                             name: cx
1618                                                 .tcx
1619                                                 .associated_item(proj.projection_ty.item_def_id)
1620                                                 .name,
1621                                             kind: TypeBindingKind::Equality {
1622                                                 term: proj.term.clean(cx),
1623                                             },
1624                                         })
1625                                     } else {
1626                                         None
1627                                     }
1628                                 } else {
1629                                     None
1630                                 }
1631                             })
1632                             .collect();
1633
1634                         Some(clean_poly_trait_ref_with_bindings(cx, trait_ref, &bindings))
1635                     })
1636                     .collect::<Vec<_>>();
1637                 bounds.extend(regions);
1638                 if !has_sized && !bounds.is_empty() {
1639                     bounds.insert(0, GenericBound::maybe_sized(cx));
1640                 }
1641                 ImplTrait(bounds)
1642             }
1643
1644             ty::Closure(..) | ty::Generator(..) => Tuple(vec![]), // FIXME(pcwalton)
1645
1646             ty::Bound(..) => panic!("Bound"),
1647             ty::Placeholder(..) => panic!("Placeholder"),
1648             ty::GeneratorWitness(..) => panic!("GeneratorWitness"),
1649             ty::Infer(..) => panic!("Infer"),
1650             ty::Error(_) => panic!("Error"),
1651         }
1652     }
1653 }
1654
1655 impl<'tcx> Clean<Constant> for ty::Const<'tcx> {
1656     fn clean(&self, cx: &mut DocContext<'_>) -> Constant {
1657         // FIXME: instead of storing the stringified expression, store `self` directly instead.
1658         Constant {
1659             type_: self.ty().clean(cx),
1660             kind: ConstantKind::TyConst { expr: self.to_string() },
1661         }
1662     }
1663 }
1664
1665 impl Clean<Item> for hir::FieldDef<'_> {
1666     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1667         let def_id = cx.tcx.hir().local_def_id(self.hir_id).to_def_id();
1668         clean_field(def_id, self.ident.name, self.ty.clean(cx), cx)
1669     }
1670 }
1671
1672 impl Clean<Item> for ty::FieldDef {
1673     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1674         clean_field(self.did, self.name, cx.tcx.type_of(self.did).clean(cx), cx)
1675     }
1676 }
1677
1678 fn clean_field(def_id: DefId, name: Symbol, ty: Type, cx: &mut DocContext<'_>) -> Item {
1679     let what_rustc_thinks =
1680         Item::from_def_id_and_parts(def_id, Some(name), StructFieldItem(ty), cx);
1681     if is_field_vis_inherited(cx.tcx, def_id) {
1682         // Variant fields inherit their enum's visibility.
1683         Item { visibility: Visibility::Inherited, ..what_rustc_thinks }
1684     } else {
1685         what_rustc_thinks
1686     }
1687 }
1688
1689 fn is_field_vis_inherited(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
1690     let parent = tcx
1691         .parent(def_id)
1692         .expect("is_field_vis_inherited can only be called on struct or variant fields");
1693     match tcx.def_kind(parent) {
1694         DefKind::Struct | DefKind::Union => false,
1695         DefKind::Variant => true,
1696         // FIXME: what about DefKind::Ctor?
1697         parent_kind => panic!("unexpected parent kind: {:?}", parent_kind),
1698     }
1699 }
1700
1701 impl Clean<Visibility> for ty::Visibility {
1702     fn clean(&self, _cx: &mut DocContext<'_>) -> Visibility {
1703         match *self {
1704             ty::Visibility::Public => Visibility::Public,
1705             // NOTE: this is not quite right: `ty` uses `Invisible` to mean 'private',
1706             // while rustdoc really does mean inherited. That means that for enum variants, such as
1707             // `pub enum E { V }`, `V` will be marked as `Public` by `ty`, but as `Inherited` by rustdoc.
1708             // Various parts of clean override `tcx.visibility` explicitly to make sure this distinction is captured.
1709             ty::Visibility::Invisible => Visibility::Inherited,
1710             ty::Visibility::Restricted(module) => Visibility::Restricted(module),
1711         }
1712     }
1713 }
1714
1715 impl Clean<VariantStruct> for rustc_hir::VariantData<'_> {
1716     fn clean(&self, cx: &mut DocContext<'_>) -> VariantStruct {
1717         VariantStruct {
1718             struct_type: CtorKind::from_hir(self),
1719             fields: self.fields().iter().map(|x| x.clean(cx)).collect(),
1720             fields_stripped: false,
1721         }
1722     }
1723 }
1724
1725 impl Clean<Vec<Item>> for hir::VariantData<'_> {
1726     fn clean(&self, cx: &mut DocContext<'_>) -> Vec<Item> {
1727         self.fields().iter().map(|x| x.clean(cx)).collect()
1728     }
1729 }
1730
1731 impl Clean<Item> for ty::VariantDef {
1732     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1733         let kind = match self.ctor_kind {
1734             CtorKind::Const => Variant::CLike,
1735             CtorKind::Fn => {
1736                 Variant::Tuple(self.fields.iter().map(|field| field.clean(cx)).collect())
1737             }
1738             CtorKind::Fictive => Variant::Struct(VariantStruct {
1739                 struct_type: CtorKind::Fictive,
1740                 fields_stripped: false,
1741                 fields: self.fields.iter().map(|field| field.clean(cx)).collect(),
1742             }),
1743         };
1744         let what_rustc_thinks =
1745             Item::from_def_id_and_parts(self.def_id, Some(self.name), VariantItem(kind), cx);
1746         // don't show `pub` for variants, which always inherit visibility
1747         Item { visibility: Inherited, ..what_rustc_thinks }
1748     }
1749 }
1750
1751 impl Clean<Variant> for hir::VariantData<'_> {
1752     fn clean(&self, cx: &mut DocContext<'_>) -> Variant {
1753         match self {
1754             hir::VariantData::Struct(..) => Variant::Struct(self.clean(cx)),
1755             hir::VariantData::Tuple(..) => Variant::Tuple(self.clean(cx)),
1756             hir::VariantData::Unit(..) => Variant::CLike,
1757         }
1758     }
1759 }
1760
1761 impl Clean<Path> for hir::Path<'_> {
1762     fn clean(&self, cx: &mut DocContext<'_>) -> Path {
1763         Path { res: self.res, segments: self.segments.iter().map(|x| x.clean(cx)).collect() }
1764     }
1765 }
1766
1767 impl Clean<GenericArgs> for hir::GenericArgs<'_> {
1768     fn clean(&self, cx: &mut DocContext<'_>) -> GenericArgs {
1769         if self.parenthesized {
1770             let output = self.bindings[0].ty().clean(cx);
1771             let output =
1772                 if output != Type::Tuple(Vec::new()) { Some(Box::new(output)) } else { None };
1773             let inputs = self.inputs().iter().map(|x| x.clean(cx)).collect();
1774             GenericArgs::Parenthesized { inputs, output }
1775         } else {
1776             let args = self
1777                 .args
1778                 .iter()
1779                 .map(|arg| match arg {
1780                     hir::GenericArg::Lifetime(lt) if !lt.is_elided() => {
1781                         GenericArg::Lifetime(lt.clean(cx))
1782                     }
1783                     hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
1784                     hir::GenericArg::Type(ty) => GenericArg::Type(ty.clean(cx)),
1785                     hir::GenericArg::Const(ct) => GenericArg::Const(Box::new(ct.clean(cx))),
1786                     hir::GenericArg::Infer(_inf) => GenericArg::Infer,
1787                 })
1788                 .collect();
1789             let bindings = self.bindings.iter().map(|x| x.clean(cx)).collect();
1790             GenericArgs::AngleBracketed { args, bindings }
1791         }
1792     }
1793 }
1794
1795 impl Clean<PathSegment> for hir::PathSegment<'_> {
1796     fn clean(&self, cx: &mut DocContext<'_>) -> PathSegment {
1797         PathSegment { name: self.ident.name, args: self.args().clean(cx) }
1798     }
1799 }
1800
1801 impl Clean<BareFunctionDecl> for hir::BareFnTy<'_> {
1802     fn clean(&self, cx: &mut DocContext<'_>) -> BareFunctionDecl {
1803         let (generic_params, decl) = enter_impl_trait(cx, |cx| {
1804             // NOTE: generics must be cleaned before args
1805             let generic_params = self.generic_params.iter().map(|x| x.clean(cx)).collect();
1806             let args = clean_args_from_types_and_names(cx, self.decl.inputs, self.param_names);
1807             let decl = clean_fn_decl_with_args(cx, self.decl, args);
1808             (generic_params, decl)
1809         });
1810         BareFunctionDecl { unsafety: self.unsafety, abi: self.abi, decl, generic_params }
1811     }
1812 }
1813
1814 fn clean_maybe_renamed_item(
1815     cx: &mut DocContext<'_>,
1816     item: &hir::Item<'_>,
1817     renamed: Option<Symbol>,
1818 ) -> Vec<Item> {
1819     use hir::ItemKind;
1820
1821     let def_id = item.def_id.to_def_id();
1822     let mut name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
1823     cx.with_param_env(def_id, |cx| {
1824         let kind = match item.kind {
1825             ItemKind::Static(ty, mutability, body_id) => {
1826                 StaticItem(Static { type_: ty.clean(cx), mutability, expr: Some(body_id) })
1827             }
1828             ItemKind::Const(ty, body_id) => ConstantItem(Constant {
1829                 type_: ty.clean(cx),
1830                 kind: ConstantKind::Local { body: body_id, def_id },
1831             }),
1832             ItemKind::OpaqueTy(ref ty) => OpaqueTyItem(OpaqueTy {
1833                 bounds: ty.bounds.iter().filter_map(|x| x.clean(cx)).collect(),
1834                 generics: ty.generics.clean(cx),
1835             }),
1836             ItemKind::TyAlias(hir_ty, ref generics) => {
1837                 let rustdoc_ty = hir_ty.clean(cx);
1838                 let ty = hir_ty_to_ty(cx.tcx, hir_ty).clean(cx);
1839                 TypedefItem(
1840                     Typedef {
1841                         type_: rustdoc_ty,
1842                         generics: generics.clean(cx),
1843                         item_type: Some(ty),
1844                     },
1845                     false,
1846                 )
1847             }
1848             ItemKind::Enum(ref def, ref generics) => EnumItem(Enum {
1849                 variants: def.variants.iter().map(|v| v.clean(cx)).collect(),
1850                 generics: generics.clean(cx),
1851                 variants_stripped: false,
1852             }),
1853             ItemKind::TraitAlias(ref generics, bounds) => TraitAliasItem(TraitAlias {
1854                 generics: generics.clean(cx),
1855                 bounds: bounds.iter().filter_map(|x| x.clean(cx)).collect(),
1856             }),
1857             ItemKind::Union(ref variant_data, ref generics) => UnionItem(Union {
1858                 generics: generics.clean(cx),
1859                 fields: variant_data.fields().iter().map(|x| x.clean(cx)).collect(),
1860                 fields_stripped: false,
1861             }),
1862             ItemKind::Struct(ref variant_data, ref generics) => StructItem(Struct {
1863                 struct_type: CtorKind::from_hir(variant_data),
1864                 generics: generics.clean(cx),
1865                 fields: variant_data.fields().iter().map(|x| x.clean(cx)).collect(),
1866                 fields_stripped: false,
1867             }),
1868             ItemKind::Impl(ref impl_) => return clean_impl(impl_, item.hir_id(), cx),
1869             // proc macros can have a name set by attributes
1870             ItemKind::Fn(ref sig, ref generics, body_id) => {
1871                 clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
1872             }
1873             ItemKind::Macro(ref macro_def, _) => {
1874                 let ty_vis = cx.tcx.visibility(def_id).clean(cx);
1875                 MacroItem(Macro {
1876                     source: display_macro_source(cx, name, macro_def, def_id, ty_vis),
1877                 })
1878             }
1879             ItemKind::Trait(is_auto, unsafety, ref generics, bounds, item_ids) => {
1880                 let items =
1881                     item_ids.iter().map(|ti| cx.tcx.hir().trait_item(ti.id).clean(cx)).collect();
1882                 TraitItem(Trait {
1883                     unsafety,
1884                     items,
1885                     generics: generics.clean(cx),
1886                     bounds: bounds.iter().filter_map(|x| x.clean(cx)).collect(),
1887                     is_auto: is_auto.clean(cx),
1888                 })
1889             }
1890             ItemKind::ExternCrate(orig_name) => {
1891                 return clean_extern_crate(item, name, orig_name, cx);
1892             }
1893             ItemKind::Use(path, kind) => {
1894                 return clean_use_statement(item, name, path, kind, cx);
1895             }
1896             _ => unreachable!("not yet converted"),
1897         };
1898
1899         vec![Item::from_def_id_and_parts(def_id, Some(name), kind, cx)]
1900     })
1901 }
1902
1903 impl Clean<Item> for hir::Variant<'_> {
1904     fn clean(&self, cx: &mut DocContext<'_>) -> Item {
1905         let kind = VariantItem(self.data.clean(cx));
1906         let what_rustc_thinks =
1907             Item::from_hir_id_and_parts(self.id, Some(self.ident.name), kind, cx);
1908         // don't show `pub` for variants, which are always public
1909         Item { visibility: Inherited, ..what_rustc_thinks }
1910     }
1911 }
1912
1913 fn clean_impl(impl_: &hir::Impl<'_>, hir_id: hir::HirId, cx: &mut DocContext<'_>) -> Vec<Item> {
1914     let tcx = cx.tcx;
1915     let mut ret = Vec::new();
1916     let trait_ = impl_.of_trait.as_ref().map(|t| t.clean(cx));
1917     let items =
1918         impl_.items.iter().map(|ii| tcx.hir().impl_item(ii.id).clean(cx)).collect::<Vec<_>>();
1919     let def_id = tcx.hir().local_def_id(hir_id);
1920
1921     // If this impl block is an implementation of the Deref trait, then we
1922     // need to try inlining the target's inherent impl blocks as well.
1923     if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
1924         build_deref_target_impls(cx, &items, &mut ret);
1925     }
1926
1927     let for_ = impl_.self_ty.clean(cx);
1928     let type_alias = for_.def_id(&cx.cache).and_then(|did| match tcx.def_kind(did) {
1929         DefKind::TyAlias => Some(tcx.type_of(did).clean(cx)),
1930         _ => None,
1931     });
1932     let mut make_item = |trait_: Option<Path>, for_: Type, items: Vec<Item>| {
1933         let kind = ImplItem(Impl {
1934             unsafety: impl_.unsafety,
1935             generics: impl_.generics.clean(cx),
1936             trait_,
1937             for_,
1938             items,
1939             polarity: tcx.impl_polarity(def_id),
1940             kind: ImplKind::Normal,
1941         });
1942         Item::from_hir_id_and_parts(hir_id, None, kind, cx)
1943     };
1944     if let Some(type_alias) = type_alias {
1945         ret.push(make_item(trait_.clone(), type_alias, items.clone()));
1946     }
1947     ret.push(make_item(trait_, for_, items));
1948     ret
1949 }
1950
1951 fn clean_extern_crate(
1952     krate: &hir::Item<'_>,
1953     name: Symbol,
1954     orig_name: Option<Symbol>,
1955     cx: &mut DocContext<'_>,
1956 ) -> Vec<Item> {
1957     // this is the ID of the `extern crate` statement
1958     let cnum = cx.tcx.extern_mod_stmt_cnum(krate.def_id).unwrap_or(LOCAL_CRATE);
1959     // this is the ID of the crate itself
1960     let crate_def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
1961     let attrs = cx.tcx.hir().attrs(krate.hir_id());
1962     let ty_vis = cx.tcx.visibility(krate.def_id);
1963     let please_inline = ty_vis.is_public()
1964         && attrs.iter().any(|a| {
1965             a.has_name(sym::doc)
1966                 && match a.meta_item_list() {
1967                     Some(l) => attr::list_contains_name(&l, sym::inline),
1968                     None => false,
1969                 }
1970         });
1971
1972     if please_inline {
1973         let mut visited = FxHashSet::default();
1974
1975         let res = Res::Def(DefKind::Mod, crate_def_id);
1976
1977         if let Some(items) = inline::try_inline(
1978             cx,
1979             cx.tcx.parent_module(krate.hir_id()).to_def_id(),
1980             Some(krate.def_id.to_def_id()),
1981             res,
1982             name,
1983             Some(attrs),
1984             &mut visited,
1985         ) {
1986             return items;
1987         }
1988     }
1989
1990     // FIXME: using `from_def_id_and_kind` breaks `rustdoc/masked` for some reason
1991     vec![Item {
1992         name: Some(name),
1993         attrs: box attrs.clean(cx),
1994         def_id: crate_def_id.into(),
1995         visibility: ty_vis.clean(cx),
1996         kind: box ExternCrateItem { src: orig_name },
1997         cfg: attrs.cfg(cx.tcx, &cx.cache.hidden_cfg),
1998     }]
1999 }
2000
2001 fn clean_use_statement(
2002     import: &hir::Item<'_>,
2003     name: Symbol,
2004     path: &hir::Path<'_>,
2005     kind: hir::UseKind,
2006     cx: &mut DocContext<'_>,
2007 ) -> Vec<Item> {
2008     // We need this comparison because some imports (for std types for example)
2009     // are "inserted" as well but directly by the compiler and they should not be
2010     // taken into account.
2011     if import.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
2012         return Vec::new();
2013     }
2014
2015     let visibility = cx.tcx.visibility(import.def_id);
2016     let attrs = cx.tcx.hir().attrs(import.hir_id());
2017     let inline_attr = attrs.lists(sym::doc).get_word_attr(sym::inline);
2018     let pub_underscore = visibility.is_public() && name == kw::Underscore;
2019     let current_mod = cx.tcx.parent_module_from_def_id(import.def_id);
2020
2021     // The parent of the module in which this import resides. This
2022     // is the same as `current_mod` if that's already the top
2023     // level module.
2024     let parent_mod = cx.tcx.parent_module_from_def_id(current_mod);
2025
2026     // This checks if the import can be seen from a higher level module.
2027     // In other words, it checks if the visibility is the equivalent of
2028     // `pub(super)` or higher. If the current module is the top level
2029     // module, there isn't really a parent module, which makes the results
2030     // meaningless. In this case, we make sure the answer is `false`.
2031     let is_visible_from_parent_mod = visibility.is_accessible_from(parent_mod.to_def_id(), cx.tcx)
2032         && !current_mod.is_top_level_module();
2033
2034     if pub_underscore {
2035         if let Some(ref inline) = inline_attr {
2036             rustc_errors::struct_span_err!(
2037                 cx.tcx.sess,
2038                 inline.span(),
2039                 E0780,
2040                 "anonymous imports cannot be inlined"
2041             )
2042             .span_label(import.span, "anonymous import")
2043             .emit();
2044         }
2045     }
2046
2047     // We consider inlining the documentation of `pub use` statements, but we
2048     // forcefully don't inline if this is not public or if the
2049     // #[doc(no_inline)] attribute is present.
2050     // Don't inline doc(hidden) imports so they can be stripped at a later stage.
2051     let mut denied = !(visibility.is_public()
2052         || (cx.render_options.document_private && is_visible_from_parent_mod))
2053         || pub_underscore
2054         || attrs.iter().any(|a| {
2055             a.has_name(sym::doc)
2056                 && match a.meta_item_list() {
2057                     Some(l) => {
2058                         attr::list_contains_name(&l, sym::no_inline)
2059                             || attr::list_contains_name(&l, sym::hidden)
2060                     }
2061                     None => false,
2062                 }
2063         });
2064
2065     // Also check whether imports were asked to be inlined, in case we're trying to re-export a
2066     // crate in Rust 2018+
2067     let path = path.clean(cx);
2068     let inner = if kind == hir::UseKind::Glob {
2069         if !denied {
2070             let mut visited = FxHashSet::default();
2071             if let Some(items) = inline::try_inline_glob(cx, path.res, &mut visited) {
2072                 return items;
2073             }
2074         }
2075         Import::new_glob(resolve_use_source(cx, path), true)
2076     } else {
2077         if inline_attr.is_none() {
2078             if let Res::Def(DefKind::Mod, did) = path.res {
2079                 if !did.is_local() && did.index == CRATE_DEF_INDEX {
2080                     // if we're `pub use`ing an extern crate root, don't inline it unless we
2081                     // were specifically asked for it
2082                     denied = true;
2083                 }
2084             }
2085         }
2086         if !denied {
2087             let mut visited = FxHashSet::default();
2088             let import_def_id = import.def_id.to_def_id();
2089
2090             if let Some(mut items) = inline::try_inline(
2091                 cx,
2092                 cx.tcx.parent_module(import.hir_id()).to_def_id(),
2093                 Some(import_def_id),
2094                 path.res,
2095                 name,
2096                 Some(attrs),
2097                 &mut visited,
2098             ) {
2099                 items.push(Item::from_def_id_and_parts(
2100                     import_def_id,
2101                     None,
2102                     ImportItem(Import::new_simple(name, resolve_use_source(cx, path), false)),
2103                     cx,
2104                 ));
2105                 return items;
2106             }
2107         }
2108         Import::new_simple(name, resolve_use_source(cx, path), true)
2109     };
2110
2111     vec![Item::from_def_id_and_parts(import.def_id.to_def_id(), None, ImportItem(inner), cx)]
2112 }
2113
2114 fn clean_maybe_renamed_foreign_item(
2115     cx: &mut DocContext<'_>,
2116     item: &hir::ForeignItem<'_>,
2117     renamed: Option<Symbol>,
2118 ) -> Item {
2119     let def_id = item.def_id.to_def_id();
2120     cx.with_param_env(def_id, |cx| {
2121         let kind = match item.kind {
2122             hir::ForeignItemKind::Fn(decl, names, ref generics) => {
2123                 let abi = cx.tcx.hir().get_foreign_abi(item.hir_id());
2124                 let (generics, decl) = enter_impl_trait(cx, |cx| {
2125                     // NOTE: generics must be cleaned before args
2126                     let generics = generics.clean(cx);
2127                     let args = clean_args_from_types_and_names(cx, decl.inputs, names);
2128                     let decl = clean_fn_decl_with_args(cx, decl, args);
2129                     (generics, decl)
2130                 });
2131                 ForeignFunctionItem(Function {
2132                     decl,
2133                     generics,
2134                     header: hir::FnHeader {
2135                         unsafety: if abi == Abi::RustIntrinsic {
2136                             intrinsic_operation_unsafety(item.ident.name)
2137                         } else {
2138                             hir::Unsafety::Unsafe
2139                         },
2140                         abi,
2141                         constness: hir::Constness::NotConst,
2142                         asyncness: hir::IsAsync::NotAsync,
2143                     },
2144                 })
2145             }
2146             hir::ForeignItemKind::Static(ref ty, mutability) => {
2147                 ForeignStaticItem(Static { type_: ty.clean(cx), mutability, expr: None })
2148             }
2149             hir::ForeignItemKind::Type => ForeignTypeItem,
2150         };
2151
2152         Item::from_hir_id_and_parts(
2153             item.hir_id(),
2154             Some(renamed.unwrap_or(item.ident.name)),
2155             kind,
2156             cx,
2157         )
2158     })
2159 }
2160
2161 impl Clean<TypeBinding> for hir::TypeBinding<'_> {
2162     fn clean(&self, cx: &mut DocContext<'_>) -> TypeBinding {
2163         TypeBinding { name: self.ident.name, kind: self.kind.clean(cx) }
2164     }
2165 }
2166
2167 impl Clean<TypeBindingKind> for hir::TypeBindingKind<'_> {
2168     fn clean(&self, cx: &mut DocContext<'_>) -> TypeBindingKind {
2169         match *self {
2170             hir::TypeBindingKind::Equality { ref term } => {
2171                 TypeBindingKind::Equality { term: term.clean(cx) }
2172             }
2173             hir::TypeBindingKind::Constraint { ref bounds } => TypeBindingKind::Constraint {
2174                 bounds: bounds.iter().filter_map(|b| b.clean(cx)).collect(),
2175             },
2176         }
2177     }
2178 }