src/librustdoc/clean/mod.rs

   1 //! This module contains the "cleaned" pieces of the AST, and the functions
   2 //! that clean them.
   3
   4 mod auto_trait;
   5 mod blanket_impl;
   6 pub mod cfg;
   7 pub mod inline;
   8 mod simplify;
   9 pub mod types;
  10 pub mod utils;
  11
  12 use rustc_ast as ast;
  13 use rustc_attr as attr;
  14 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  15 use rustc_hir as hir;
  16 use rustc_hir::def::{CtorKind, DefKind, Res};
  17 use rustc_hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX};
  18 use rustc_index::vec::{Idx, IndexVec};
  19 use rustc_infer::infer::region_constraints::{Constraint, RegionConstraintData};
  20 use rustc_middle::bug;
  21 use rustc_middle::middle::resolve_lifetime as rl;
  22 use rustc_middle::middle::stability;
  23 use rustc_middle::ty::fold::TypeFolder;
  24 use rustc_middle::ty::subst::InternalSubsts;
  25 use rustc_middle::ty::{self, AdtKind, Lift, Ty, TyCtxt};
  26 use rustc_mir::const_eval::is_min_const_fn;
  27 use rustc_span::hygiene::MacroKind;
  28 use rustc_span::symbol::{kw, sym, Ident, Symbol};
  29 use rustc_span::{self, Pos};
  30 use rustc_typeck::hir_ty_to_ty;
  31
  32 use std::collections::hash_map::Entry;
  33 use std::default::Default;
  34 use std::hash::Hash;
  35 use std::rc::Rc;
  36 use std::{mem, vec};
  37
  38 use crate::core::{self, DocContext, ImplTraitParam};
  39 use crate::doctree;
  40
  41 use utils::*;
  42
  43 pub use utils::{get_auto_trait_and_blanket_impls, krate, register_res};
  44
  45 pub use self::types::FnRetTy::*;
  46 pub use self::types::ItemEnum::*;
  47 pub use self::types::SelfTy::*;
  48 pub use self::types::Type::*;
  49 pub use self::types::Visibility::{Inherited, Public};
  50 pub use self::types::*;
  51
  52 const FN_OUTPUT_NAME: &str = "Output";
  53
  54 pub trait Clean<T> {
  55     fn clean(&self, cx: &DocContext<'_>) -> T;
  56 }
  57
  58 impl<T: Clean<U>, U> Clean<Vec<U>> for [T] {
  59     fn clean(&self, cx: &DocContext<'_>) -> Vec<U> {
  60         self.iter().map(|x| x.clean(cx)).collect()
  61     }
  62 }
  63
  64 impl<T: Clean<U>, U, V: Idx> Clean<IndexVec<V, U>> for IndexVec<V, T> {
  65     fn clean(&self, cx: &DocContext<'_>) -> IndexVec<V, U> {
  66         self.iter().map(|x| x.clean(cx)).collect()
  67     }
  68 }
  69
  70 impl<T: Clean<U>, U> Clean<U> for &T {
  71     fn clean(&self, cx: &DocContext<'_>) -> U {
  72         (**self).clean(cx)
  73     }
  74 }
  75
  76 impl<T: Clean<U>, U> Clean<U> for Rc<T> {
  77     fn clean(&self, cx: &DocContext<'_>) -> U {
  78         (**self).clean(cx)
  79     }
  80 }
  81
  82 impl<T: Clean<U>, U> Clean<Option<U>> for Option<T> {
  83     fn clean(&self, cx: &DocContext<'_>) -> Option<U> {
  84         self.as_ref().map(|v| v.clean(cx))
  85     }
  86 }
  87
  88 impl Clean<ExternalCrate> for CrateNum {
  89     fn clean(&self, cx: &DocContext<'_>) -> ExternalCrate {
  90         let root = DefId { krate: *self, index: CRATE_DEF_INDEX };
  91         let krate_span = cx.tcx.def_span(root);
  92         let krate_src = cx.sess().source_map().span_to_filename(krate_span);
  93
  94         // Collect all inner modules which are tagged as implementations of
  95         // primitives.
  96         //
  97         // Note that this loop only searches the top-level items of the crate,
  98         // and this is intentional. If we were to search the entire crate for an
  99         // item tagged with `#[doc(primitive)]` then we would also have to
 100         // search the entirety of external modules for items tagged
 101         // `#[doc(primitive)]`, which is a pretty inefficient process (decoding
 102         // all that metadata unconditionally).
 103         //
 104         // In order to keep the metadata load under control, the
 105         // `#[doc(primitive)]` feature is explicitly designed to only allow the
 106         // primitive tags to show up as the top level items in a crate.
 107         //
 108         // Also note that this does not attempt to deal with modules tagged
 109         // duplicately for the same primitive. This is handled later on when
 110         // rendering by delegating everything to a hash map.
 111         let as_primitive = |res: Res| {
 112             if let Res::Def(DefKind::Mod, def_id) = res {
 113                 let attrs = cx.tcx.get_attrs(def_id).clean(cx);
 114                 let mut prim = None;
 115                 for attr in attrs.lists(sym::doc) {
 116                     if let Some(v) = attr.value_str() {
 117                         if attr.has_name(sym::primitive) {
 118                             prim = PrimitiveType::from_symbol(v);
 119                             if prim.is_some() {
 120                                 break;
 121                             }
 122                             // FIXME: should warn on unknown primitives?
 123                         }
 124                     }
 125                 }
 126                 return prim.map(|p| (def_id, p, attrs));
 127             }
 128             None
 129         };
 130         let primitives = if root.is_local() {
 131             cx.tcx
 132                 .hir()
 133                 .krate()
 134                 .item
 135                 .module
 136                 .item_ids
 137                 .iter()
 138                 .filter_map(|&id| {
 139                     let item = cx.tcx.hir().expect_item(id.id);
 140                     match item.kind {
 141                         hir::ItemKind::Mod(_) => as_primitive(Res::Def(
 142                             DefKind::Mod,
 143                             cx.tcx.hir().local_def_id(id.id).to_def_id(),
 144                         )),
 145                         hir::ItemKind::Use(ref path, hir::UseKind::Single)
 146                             if item.vis.node.is_pub() =>
 147                         {
 148                             as_primitive(path.res).map(|(_, prim, attrs)| {
 149                                 // Pretend the primitive is local.
 150                                 (cx.tcx.hir().local_def_id(id.id).to_def_id(), prim, attrs)
 151                             })
 152                         }
 153                         _ => None,
 154                     }
 155                 })
 156                 .collect()
 157         } else {
 158             cx.tcx
 159                 .item_children(root)
 160                 .iter()
 161                 .map(|item| item.res)
 162                 .filter_map(as_primitive)
 163                 .collect()
 164         };
 165
 166         let as_keyword = |res: Res| {
 167             if let Res::Def(DefKind::Mod, def_id) = res {
 168                 let attrs = cx.tcx.get_attrs(def_id).clean(cx);
 169                 let mut keyword = None;
 170                 for attr in attrs.lists(sym::doc) {
 171                     if let Some(v) = attr.value_str() {
 172                         if attr.has_name(sym::keyword) {
 173                             if v.is_doc_keyword() {
 174                                 keyword = Some(v.to_string());
 175                                 break;
 176                             }
 177                             // FIXME: should warn on unknown keywords?
 178                         }
 179                     }
 180                 }
 181                 return keyword.map(|p| (def_id, p, attrs));
 182             }
 183             None
 184         };
 185         let keywords = if root.is_local() {
 186             cx.tcx
 187                 .hir()
 188                 .krate()
 189                 .item
 190                 .module
 191                 .item_ids
 192                 .iter()
 193                 .filter_map(|&id| {
 194                     let item = cx.tcx.hir().expect_item(id.id);
 195                     match item.kind {
 196                         hir::ItemKind::Mod(_) => as_keyword(Res::Def(
 197                             DefKind::Mod,
 198                             cx.tcx.hir().local_def_id(id.id).to_def_id(),
 199                         )),
 200                         hir::ItemKind::Use(ref path, hir::UseKind::Single)
 201                             if item.vis.node.is_pub() =>
 202                         {
 203                             as_keyword(path.res).map(|(_, prim, attrs)| {
 204                                 (cx.tcx.hir().local_def_id(id.id).to_def_id(), prim, attrs)
 205                             })
 206                         }
 207                         _ => None,
 208                     }
 209                 })
 210                 .collect()
 211         } else {
 212             cx.tcx.item_children(root).iter().map(|item| item.res).filter_map(as_keyword).collect()
 213         };
 214
 215         ExternalCrate {
 216             name: cx.tcx.crate_name(*self).to_string(),
 217             src: krate_src,
 218             attrs: cx.tcx.get_attrs(root).clean(cx),
 219             primitives,
 220             keywords,
 221         }
 222     }
 223 }
 224
 225 impl Clean<Item> for doctree::Module<'_> {
 226     fn clean(&self, cx: &DocContext<'_>) -> Item {
 227         let name = if self.name.is_some() {
 228             self.name.expect("No name provided").clean(cx)
 229         } else {
 230             String::new()
 231         };
 232
 233         // maintain a stack of mod ids, for doc comment path resolution
 234         // but we also need to resolve the module's own docs based on whether its docs were written
 235         // inside or outside the module, so check for that
 236         let attrs = self.attrs.clean(cx);
 237
 238         let mut items: Vec<Item> = vec![];
 239         items.extend(self.extern_crates.iter().flat_map(|x| x.clean(cx)));
 240         items.extend(self.imports.iter().flat_map(|x| x.clean(cx)));
 241         items.extend(self.structs.iter().map(|x| x.clean(cx)));
 242         items.extend(self.unions.iter().map(|x| x.clean(cx)));
 243         items.extend(self.enums.iter().map(|x| x.clean(cx)));
 244         items.extend(self.fns.iter().map(|x| x.clean(cx)));
 245         items.extend(self.foreigns.iter().map(|x| x.clean(cx)));
 246         items.extend(self.mods.iter().map(|x| x.clean(cx)));
 247         items.extend(self.typedefs.iter().map(|x| x.clean(cx)));
 248         items.extend(self.opaque_tys.iter().map(|x| x.clean(cx)));
 249         items.extend(self.statics.iter().map(|x| x.clean(cx)));
 250         items.extend(self.constants.iter().map(|x| x.clean(cx)));
 251         items.extend(self.traits.iter().map(|x| x.clean(cx)));
 252         items.extend(self.impls.iter().flat_map(|x| x.clean(cx)));
 253         items.extend(self.macros.iter().map(|x| x.clean(cx)));
 254         items.extend(self.proc_macros.iter().map(|x| x.clean(cx)));
 255         items.extend(self.trait_aliases.iter().map(|x| x.clean(cx)));
 256
 257         // determine if we should display the inner contents or
 258         // the outer `mod` item for the source code.
 259         let whence = {
 260             let sm = cx.sess().source_map();
 261             let outer = sm.lookup_char_pos(self.where_outer.lo());
 262             let inner = sm.lookup_char_pos(self.where_inner.lo());
 263             if outer.file.start_pos == inner.file.start_pos {
 264                 // mod foo { ... }
 265                 self.where_outer
 266             } else {
 267                 // mod foo; (and a separate SourceFile for the contents)
 268                 self.where_inner
 269             }
 270         };
 271
 272         Item {
 273             name: Some(name),
 274             attrs,
 275             source: whence.clean(cx),
 276             visibility: self.vis.clean(cx),
 277             stability: cx.stability(self.id).clean(cx),
 278             deprecation: cx.deprecation(self.id).clean(cx),
 279             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
 280             inner: ModuleItem(Module { is_crate: self.is_crate, items }),
 281         }
 282     }
 283 }
 284
 285 impl Clean<Attributes> for [ast::Attribute] {
 286     fn clean(&self, cx: &DocContext<'_>) -> Attributes {
 287         Attributes::from_ast(cx.sess().diagnostic(), self)
 288     }
 289 }
 290
 291 impl Clean<GenericBound> for hir::GenericBound<'_> {
 292     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
 293         match *self {
 294             hir::GenericBound::Outlives(lt) => GenericBound::Outlives(lt.clean(cx)),
 295             hir::GenericBound::LangItemTrait(lang_item, span, _, generic_args) => {
 296                 let def_id = cx.tcx.require_lang_item(lang_item, Some(span));
 297
 298                 let trait_ref = ty::TraitRef::identity(cx.tcx, def_id);
 299
 300                 let generic_args = generic_args.clean(cx);
 301                 let bindings = match generic_args {
 302                     GenericArgs::AngleBracketed { bindings, .. } => bindings,
 303                     _ => bug!("clean: parenthesized `GenericBound::LangItemTrait`"),
 304                 };
 305
 306                 GenericBound::TraitBound(
 307                     PolyTrait { trait_: (trait_ref, &*bindings).clean(cx), generic_params: vec![] },
 308                     hir::TraitBoundModifier::None,
 309                 )
 310             }
 311             hir::GenericBound::Trait(ref t, modifier) => {
 312                 GenericBound::TraitBound(t.clean(cx), modifier)
 313             }
 314         }
 315     }
 316 }
 317
 318 impl Clean<Type> for (ty::TraitRef<'_>, &[TypeBinding]) {
 319     fn clean(&self, cx: &DocContext<'_>) -> Type {
 320         let (trait_ref, bounds) = *self;
 321         inline::record_extern_fqn(cx, trait_ref.def_id, TypeKind::Trait);
 322         let path = external_path(
 323             cx,
 324             cx.tcx.item_name(trait_ref.def_id),
 325             Some(trait_ref.def_id),
 326             true,
 327             bounds.to_vec(),
 328             trait_ref.substs,
 329         );
 330
 331         debug!("ty::TraitRef\n  subst: {:?}\n", trait_ref.substs);
 332
 333         ResolvedPath { path, param_names: None, did: trait_ref.def_id, is_generic: false }
 334     }
 335 }
 336
 337 impl<'tcx> Clean<GenericBound> for ty::TraitRef<'tcx> {
 338     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
 339         GenericBound::TraitBound(
 340             PolyTrait { trait_: (*self, &[][..]).clean(cx), generic_params: vec![] },
 341             hir::TraitBoundModifier::None,
 342         )
 343     }
 344 }
 345
 346 impl Clean<GenericBound> for (ty::PolyTraitRef<'_>, &[TypeBinding]) {
 347     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
 348         let (poly_trait_ref, bounds) = *self;
 349         let poly_trait_ref = poly_trait_ref.lift_to_tcx(cx.tcx).unwrap();
 350
 351         // collect any late bound regions
 352         let late_bound_regions: Vec<_> = cx
 353             .tcx
 354             .collect_referenced_late_bound_regions(&poly_trait_ref)
 355             .into_iter()
 356             .filter_map(|br| match br {
 357                 ty::BrNamed(_, name) => Some(GenericParamDef {
 358                     name: name.to_string(),
 359                     kind: GenericParamDefKind::Lifetime,
 360                 }),
 361                 _ => None,
 362             })
 363             .collect();
 364
 365         GenericBound::TraitBound(
 366             PolyTrait {
 367                 trait_: (poly_trait_ref.skip_binder(), bounds).clean(cx),
 368                 generic_params: late_bound_regions,
 369             },
 370             hir::TraitBoundModifier::None,
 371         )
 372     }
 373 }
 374
 375 impl<'tcx> Clean<GenericBound> for ty::PolyTraitRef<'tcx> {
 376     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
 377         (*self, &[][..]).clean(cx)
 378     }
 379 }
 380
 381 impl<'tcx> Clean<Option<Vec<GenericBound>>> for InternalSubsts<'tcx> {
 382     fn clean(&self, cx: &DocContext<'_>) -> Option<Vec<GenericBound>> {
 383         let mut v = Vec::new();
 384         v.extend(self.regions().filter_map(|r| r.clean(cx)).map(GenericBound::Outlives));
 385         v.extend(self.types().map(|t| {
 386             GenericBound::TraitBound(
 387                 PolyTrait { trait_: t.clean(cx), generic_params: Vec::new() },
 388                 hir::TraitBoundModifier::None,
 389             )
 390         }));
 391         if !v.is_empty() { Some(v) } else { None }
 392     }
 393 }
 394
 395 impl Clean<Lifetime> for hir::Lifetime {
 396     fn clean(&self, cx: &DocContext<'_>) -> Lifetime {
 397         let def = cx.tcx.named_region(self.hir_id);
 398         match def {
 399             Some(
 400                 rl::Region::EarlyBound(_, node_id, _)
 401                 | rl::Region::LateBound(_, node_id, _)
 402                 | rl::Region::Free(_, node_id),
 403             ) => {
 404                 if let Some(lt) = cx.lt_substs.borrow().get(&node_id).cloned() {
 405                     return lt;
 406                 }
 407             }
 408             _ => {}
 409         }
 410         Lifetime(self.name.ident().to_string())
 411     }
 412 }
 413
 414 impl Clean<Lifetime> for hir::GenericParam<'_> {
 415     fn clean(&self, _: &DocContext<'_>) -> Lifetime {
 416         match self.kind {
 417             hir::GenericParamKind::Lifetime { .. } => {
 418                 if !self.bounds.is_empty() {
 419                     let mut bounds = self.bounds.iter().map(|bound| match bound {
 420                         hir::GenericBound::Outlives(lt) => lt,
 421                         _ => panic!(),
 422                     });
 423                     let name = bounds.next().expect("no more bounds").name.ident();
 424                     let mut s = format!("{}: {}", self.name.ident(), name);
 425                     for bound in bounds {
 426                         s.push_str(&format!(" + {}", bound.name.ident()));
 427                     }
 428                     Lifetime(s)
 429                 } else {
 430                     Lifetime(self.name.ident().to_string())
 431                 }
 432             }
 433             _ => panic!(),
 434         }
 435     }
 436 }
 437
 438 impl Clean<Constant> for hir::ConstArg {
 439     fn clean(&self, cx: &DocContext<'_>) -> Constant {
 440         Constant {
 441             type_: cx
 442                 .tcx
 443                 .type_of(cx.tcx.hir().body_owner_def_id(self.value.body).to_def_id())
 444                 .clean(cx),
 445             expr: print_const_expr(cx, self.value.body),
 446             value: None,
 447             is_literal: is_literal_expr(cx, self.value.body.hir_id),
 448         }
 449     }
 450 }
 451
 452 impl Clean<Lifetime> for ty::GenericParamDef {
 453     fn clean(&self, _cx: &DocContext<'_>) -> Lifetime {
 454         Lifetime(self.name.to_string())
 455     }
 456 }
 457
 458 impl Clean<Option<Lifetime>> for ty::RegionKind {
 459     fn clean(&self, cx: &DocContext<'_>) -> Option<Lifetime> {
 460         match *self {
 461             ty::ReStatic => Some(Lifetime::statik()),
 462             ty::ReLateBound(_, ty::BrNamed(_, name)) => Some(Lifetime(name.to_string())),
 463             ty::ReEarlyBound(ref data) => Some(Lifetime(data.name.clean(cx))),
 464
 465             ty::ReLateBound(..)
 466             | ty::ReFree(..)
 467             | ty::ReVar(..)
 468             | ty::RePlaceholder(..)
 469             | ty::ReEmpty(_)
 470             | ty::ReErased => {
 471                 debug!("cannot clean region {:?}", self);
 472                 None
 473             }
 474         }
 475     }
 476 }
 477
 478 impl Clean<WherePredicate> for hir::WherePredicate<'_> {
 479     fn clean(&self, cx: &DocContext<'_>) -> WherePredicate {
 480         match *self {
 481             hir::WherePredicate::BoundPredicate(ref wbp) => WherePredicate::BoundPredicate {
 482                 ty: wbp.bounded_ty.clean(cx),
 483                 bounds: wbp.bounds.clean(cx),
 484             },
 485
 486             hir::WherePredicate::RegionPredicate(ref wrp) => WherePredicate::RegionPredicate {
 487                 lifetime: wrp.lifetime.clean(cx),
 488                 bounds: wrp.bounds.clean(cx),
 489             },
 490
 491             hir::WherePredicate::EqPredicate(ref wrp) => {
 492                 WherePredicate::EqPredicate { lhs: wrp.lhs_ty.clean(cx), rhs: wrp.rhs_ty.clean(cx) }
 493             }
 494         }
 495     }
 496 }
 497
 498 impl<'a> Clean<Option<WherePredicate>> for ty::Predicate<'a> {
 499     fn clean(&self, cx: &DocContext<'_>) -> Option<WherePredicate> {
 500         match self.skip_binders() {
 501             ty::PredicateAtom::Trait(pred, _) => Some(ty::Binder::bind(pred).clean(cx)),
 502             ty::PredicateAtom::RegionOutlives(pred) => pred.clean(cx),
 503             ty::PredicateAtom::TypeOutlives(pred) => pred.clean(cx),
 504             ty::PredicateAtom::Projection(pred) => Some(pred.clean(cx)),
 505
 506             ty::PredicateAtom::Subtype(..)
 507             | ty::PredicateAtom::WellFormed(..)
 508             | ty::PredicateAtom::ObjectSafe(..)
 509             | ty::PredicateAtom::ClosureKind(..)
 510             | ty::PredicateAtom::ConstEvaluatable(..)
 511             | ty::PredicateAtom::ConstEquate(..) => panic!("not user writable"),
 512         }
 513     }
 514 }
 515
 516 impl<'a> Clean<WherePredicate> for ty::PolyTraitPredicate<'a> {
 517     fn clean(&self, cx: &DocContext<'_>) -> WherePredicate {
 518         let poly_trait_ref = self.map_bound(|pred| pred.trait_ref);
 519         WherePredicate::BoundPredicate {
 520             ty: poly_trait_ref.skip_binder().self_ty().clean(cx),
 521             bounds: vec![poly_trait_ref.clean(cx)],
 522         }
 523     }
 524 }
 525
 526 impl<'tcx> Clean<Option<WherePredicate>>
 527     for ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
 528 {
 529     fn clean(&self, cx: &DocContext<'_>) -> Option<WherePredicate> {
 530         let ty::OutlivesPredicate(a, b) = self;
 531
 532         if let (ty::ReEmpty(_), ty::ReEmpty(_)) = (a, b) {
 533             return None;
 534         }
 535
 536         Some(WherePredicate::RegionPredicate {
 537             lifetime: a.clean(cx).expect("failed to clean lifetime"),
 538             bounds: vec![GenericBound::Outlives(b.clean(cx).expect("failed to clean bounds"))],
 539         })
 540     }
 541 }
 542
 543 impl<'tcx> Clean<Option<WherePredicate>> for ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>> {
 544     fn clean(&self, cx: &DocContext<'_>) -> Option<WherePredicate> {
 545         let ty::OutlivesPredicate(ty, lt) = self;
 546
 547         if let ty::ReEmpty(_) = lt {
 548             return None;
 549         }
 550
 551         Some(WherePredicate::BoundPredicate {
 552             ty: ty.clean(cx),
 553             bounds: vec![GenericBound::Outlives(lt.clean(cx).expect("failed to clean lifetimes"))],
 554         })
 555     }
 556 }
 557
 558 impl<'tcx> Clean<WherePredicate> for ty::ProjectionPredicate<'tcx> {
 559     fn clean(&self, cx: &DocContext<'_>) -> WherePredicate {
 560         let ty::ProjectionPredicate { projection_ty, ty } = self;
 561         WherePredicate::EqPredicate { lhs: projection_ty.clean(cx), rhs: ty.clean(cx) }
 562     }
 563 }
 564
 565 impl<'tcx> Clean<Type> for ty::ProjectionTy<'tcx> {
 566     fn clean(&self, cx: &DocContext<'_>) -> Type {
 567         let lifted = self.lift_to_tcx(cx.tcx).unwrap();
 568         let trait_ = match lifted.trait_ref(cx.tcx).clean(cx) {
 569             GenericBound::TraitBound(t, _) => t.trait_,
 570             GenericBound::Outlives(_) => panic!("cleaning a trait got a lifetime"),
 571         };
 572         Type::QPath {
 573             name: cx.tcx.associated_item(self.item_def_id).ident.name.clean(cx),
 574             self_type: box self.self_ty().clean(cx),
 575             trait_: box trait_,
 576         }
 577     }
 578 }
 579
 580 impl Clean<GenericParamDef> for ty::GenericParamDef {
 581     fn clean(&self, cx: &DocContext<'_>) -> GenericParamDef {
 582         let (name, kind) = match self.kind {
 583             ty::GenericParamDefKind::Lifetime => {
 584                 (self.name.to_string(), GenericParamDefKind::Lifetime)
 585             }
 586             ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
 587                 let default =
 588                     if has_default { Some(cx.tcx.type_of(self.def_id).clean(cx)) } else { None };
 589                 (
 590                     self.name.clean(cx),
 591                     GenericParamDefKind::Type {
 592                         did: self.def_id,
 593                         bounds: vec![], // These are filled in from the where-clauses.
 594                         default,
 595                         synthetic,
 596                     },
 597                 )
 598             }
 599             ty::GenericParamDefKind::Const { .. } => (
 600                 self.name.clean(cx),
 601                 GenericParamDefKind::Const {
 602                     did: self.def_id,
 603                     ty: cx.tcx.type_of(self.def_id).clean(cx),
 604                 },
 605             ),
 606         };
 607
 608         GenericParamDef { name, kind }
 609     }
 610 }
 611
 612 impl Clean<GenericParamDef> for hir::GenericParam<'_> {
 613     fn clean(&self, cx: &DocContext<'_>) -> GenericParamDef {
 614         let (name, kind) = match self.kind {
 615             hir::GenericParamKind::Lifetime { .. } => {
 616                 let name = if !self.bounds.is_empty() {
 617                     let mut bounds = self.bounds.iter().map(|bound| match bound {
 618                         hir::GenericBound::Outlives(lt) => lt,
 619                         _ => panic!(),
 620                     });
 621                     let name = bounds.next().expect("no more bounds").name.ident();
 622                     let mut s = format!("{}: {}", self.name.ident(), name);
 623                     for bound in bounds {
 624                         s.push_str(&format!(" + {}", bound.name.ident()));
 625                     }
 626                     s
 627                 } else {
 628                     self.name.ident().to_string()
 629                 };
 630                 (name, GenericParamDefKind::Lifetime)
 631             }
 632             hir::GenericParamKind::Type { ref default, synthetic } => (
 633                 self.name.ident().name.clean(cx),
 634                 GenericParamDefKind::Type {
 635                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
 636                     bounds: self.bounds.clean(cx),
 637                     default: default.clean(cx),
 638                     synthetic,
 639                 },
 640             ),
 641             hir::GenericParamKind::Const { ref ty } => (
 642                 self.name.ident().name.clean(cx),
 643                 GenericParamDefKind::Const {
 644                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
 645                     ty: ty.clean(cx),
 646                 },
 647             ),
 648         };
 649
 650         GenericParamDef { name, kind }
 651     }
 652 }
 653
 654 impl Clean<Generics> for hir::Generics<'_> {
 655     fn clean(&self, cx: &DocContext<'_>) -> Generics {
 656         // Synthetic type-parameters are inserted after normal ones.
 657         // In order for normal parameters to be able to refer to synthetic ones,
 658         // scans them first.
 659         fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
 660             match param.kind {
 661                 hir::GenericParamKind::Type { synthetic, .. } => {
 662                     synthetic == Some(hir::SyntheticTyParamKind::ImplTrait)
 663                 }
 664                 _ => false,
 665             }
 666         }
 667         let impl_trait_params = self
 668             .params
 669             .iter()
 670             .filter(|param| is_impl_trait(param))
 671             .map(|param| {
 672                 let param: GenericParamDef = param.clean(cx);
 673                 match param.kind {
 674                     GenericParamDefKind::Lifetime => unreachable!(),
 675                     GenericParamDefKind::Type { did, ref bounds, .. } => {
 676                         cx.impl_trait_bounds.borrow_mut().insert(did.into(), bounds.clone());
 677                     }
 678                     GenericParamDefKind::Const { .. } => unreachable!(),
 679                 }
 680                 param
 681             })
 682             .collect::<Vec<_>>();
 683
 684         let mut params = Vec::with_capacity(self.params.len());
 685         for p in self.params.iter().filter(|p| !is_impl_trait(p)) {
 686             let p = p.clean(cx);
 687             params.push(p);
 688         }
 689         params.extend(impl_trait_params);
 690
 691         let mut generics =
 692             Generics { params, where_predicates: self.where_clause.predicates.clean(cx) };
 693
 694         // Some duplicates are generated for ?Sized bounds between type params and where
 695         // predicates. The point in here is to move the bounds definitions from type params
 696         // to where predicates when such cases occur.
 697         for where_pred in &mut generics.where_predicates {
 698             match *where_pred {
 699                 WherePredicate::BoundPredicate { ty: Generic(ref name), ref mut bounds } => {
 700                     if bounds.is_empty() {
 701                         for param in &mut generics.params {
 702                             match param.kind {
 703                                 GenericParamDefKind::Lifetime => {}
 704                                 GenericParamDefKind::Type { bounds: ref mut ty_bounds, .. } => {
 705                                     if &param.name == name {
 706                                         mem::swap(bounds, ty_bounds);
 707                                         break;
 708                                     }
 709                                 }
 710                                 GenericParamDefKind::Const { .. } => {}
 711                             }
 712                         }
 713                     }
 714                 }
 715                 _ => continue,
 716             }
 717         }
 718         generics
 719     }
 720 }
 721
 722 impl<'a, 'tcx> Clean<Generics> for (&'a ty::Generics, ty::GenericPredicates<'tcx>) {
 723     fn clean(&self, cx: &DocContext<'_>) -> Generics {
 724         use self::WherePredicate as WP;
 725         use std::collections::BTreeMap;
 726
 727         let (gens, preds) = *self;
 728
 729         // Don't populate `cx.impl_trait_bounds` before `clean`ning `where` clauses,
 730         // since `Clean for ty::Predicate` would consume them.
 731         let mut impl_trait = BTreeMap::<ImplTraitParam, Vec<GenericBound>>::default();
 732
 733         // Bounds in the type_params and lifetimes fields are repeated in the
 734         // predicates field (see rustc_typeck::collect::ty_generics), so remove
 735         // them.
 736         let stripped_params = gens
 737             .params
 738             .iter()
 739             .filter_map(|param| match param.kind {
 740                 ty::GenericParamDefKind::Lifetime => Some(param.clean(cx)),
 741                 ty::GenericParamDefKind::Type { synthetic, .. } => {
 742                     if param.name == kw::SelfUpper {
 743                         assert_eq!(param.index, 0);
 744                         return None;
 745                     }
 746                     if synthetic == Some(hir::SyntheticTyParamKind::ImplTrait) {
 747                         impl_trait.insert(param.index.into(), vec![]);
 748                         return None;
 749                     }
 750                     Some(param.clean(cx))
 751                 }
 752                 ty::GenericParamDefKind::Const { .. } => Some(param.clean(cx)),
 753             })
 754             .collect::<Vec<GenericParamDef>>();
 755
 756         // param index -> [(DefId of trait, associated type name, type)]
 757         let mut impl_trait_proj = FxHashMap::<u32, Vec<(DefId, String, Ty<'tcx>)>>::default();
 758
 759         let where_predicates = preds
 760             .predicates
 761             .iter()
 762             .flat_map(|(p, _)| {
 763                 let mut projection = None;
 764                 let param_idx = (|| {
 765                     match p.skip_binders() {
 766                         ty::PredicateAtom::Trait(pred, _constness) => {
 767                             if let ty::Param(param) = pred.self_ty().kind() {
 768                                 return Some(param.index);
 769                             }
 770                         }
 771                         ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(ty, _reg)) => {
 772                             if let ty::Param(param) = ty.kind() {
 773                                 return Some(param.index);
 774                             }
 775                         }
 776                         ty::PredicateAtom::Projection(p) => {
 777                             if let ty::Param(param) = p.projection_ty.self_ty().kind() {
 778                                 projection = Some(ty::Binder::bind(p));
 779                                 return Some(param.index);
 780                             }
 781                         }
 782                         _ => (),
 783                     }
 784
 785                     None
 786                 })();
 787
 788                 if let Some(param_idx) = param_idx {
 789                     if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
 790                         let p = p.clean(cx)?;
 791
 792                         b.extend(
 793                             p.get_bounds()
 794                                 .into_iter()
 795                                 .flatten()
 796                                 .cloned()
 797                                 .filter(|b| !b.is_sized_bound(cx)),
 798                         );
 799
 800                         let proj = projection
 801                             .map(|p| (p.skip_binder().projection_ty.clean(cx), p.skip_binder().ty));
 802                         if let Some(((_, trait_did, name), rhs)) =
 803                             proj.as_ref().and_then(|(lhs, rhs)| Some((lhs.projection()?, rhs)))
 804                         {
 805                             impl_trait_proj.entry(param_idx).or_default().push((
 806                                 trait_did,
 807                                 name.to_string(),
 808                                 rhs,
 809                             ));
 810                         }
 811
 812                         return None;
 813                     }
 814                 }
 815
 816                 Some(p)
 817             })
 818             .collect::<Vec<_>>();
 819
 820         for (param, mut bounds) in impl_trait {
 821             // Move trait bounds to the front.
 822             bounds.sort_by_key(|b| if let GenericBound::TraitBound(..) = b { false } else { true });
 823
 824             if let crate::core::ImplTraitParam::ParamIndex(idx) = param {
 825                 if let Some(proj) = impl_trait_proj.remove(&idx) {
 826                     for (trait_did, name, rhs) in proj {
 827                         simplify::merge_bounds(cx, &mut bounds, trait_did, &name, &rhs.clean(cx));
 828                     }
 829                 }
 830             } else {
 831                 unreachable!();
 832             }
 833
 834             cx.impl_trait_bounds.borrow_mut().insert(param, bounds);
 835         }
 836
 837         // Now that `cx.impl_trait_bounds` is populated, we can process
 838         // remaining predicates which could contain `impl Trait`.
 839         let mut where_predicates =
 840             where_predicates.into_iter().flat_map(|p| p.clean(cx)).collect::<Vec<_>>();
 841
 842         // Type parameters and have a Sized bound by default unless removed with
 843         // ?Sized. Scan through the predicates and mark any type parameter with
 844         // a Sized bound, removing the bounds as we find them.
 845         //
 846         // Note that associated types also have a sized bound by default, but we
 847         // don't actually know the set of associated types right here so that's
 848         // handled in cleaning associated types
 849         let mut sized_params = FxHashSet::default();
 850         where_predicates.retain(|pred| match *pred {
 851             WP::BoundPredicate { ty: Generic(ref g), ref bounds } => {
 852                 if bounds.iter().any(|b| b.is_sized_bound(cx)) {
 853                     sized_params.insert(g.clone());
 854                     false
 855                 } else {
 856                     true
 857                 }
 858             }
 859             _ => true,
 860         });
 861
 862         // Run through the type parameters again and insert a ?Sized
 863         // unbound for any we didn't find to be Sized.
 864         for tp in &stripped_params {
 865             if matches!(tp.kind, types::GenericParamDefKind::Type { .. })
 866                 && !sized_params.contains(&tp.name)
 867             {
 868                 where_predicates.push(WP::BoundPredicate {
 869                     ty: Type::Generic(tp.name.clone()),
 870                     bounds: vec![GenericBound::maybe_sized(cx)],
 871                 })
 872             }
 873         }
 874
 875         // It would be nice to collect all of the bounds on a type and recombine
 876         // them if possible, to avoid e.g., `where T: Foo, T: Bar, T: Sized, T: 'a`
 877         // and instead see `where T: Foo + Bar + Sized + 'a`
 878
 879         Generics {
 880             params: stripped_params,
 881             where_predicates: simplify::where_clauses(cx, where_predicates),
 882         }
 883     }
 884 }
 885
 886 impl<'a> Clean<Method>
 887     for (&'a hir::FnSig<'a>, &'a hir::Generics<'a>, hir::BodyId, Option<hir::Defaultness>)
 888 {
 889     fn clean(&self, cx: &DocContext<'_>) -> Method {
 890         let (generics, decl) =
 891             enter_impl_trait(cx, || (self.1.clean(cx), (&*self.0.decl, self.2).clean(cx)));
 892         let (all_types, ret_types) = get_all_types(&generics, &decl, cx);
 893         Method { decl, generics, header: self.0.header, defaultness: self.3, all_types, ret_types }
 894     }
 895 }
 896
 897 impl Clean<Item> for doctree::Function<'_> {
 898     fn clean(&self, cx: &DocContext<'_>) -> Item {
 899         let (generics, decl) =
 900             enter_impl_trait(cx, || (self.generics.clean(cx), (self.decl, self.body).clean(cx)));
 901
 902         let did = cx.tcx.hir().local_def_id(self.id);
 903         let constness = if is_min_const_fn(cx.tcx, did.to_def_id()) {
 904             hir::Constness::Const
 905         } else {
 906             hir::Constness::NotConst
 907         };
 908         let (all_types, ret_types) = get_all_types(&generics, &decl, cx);
 909         Item {
 910             name: Some(self.name.clean(cx)),
 911             attrs: self.attrs.clean(cx),
 912             source: self.whence.clean(cx),
 913             visibility: self.vis.clean(cx),
 914             stability: cx.stability(self.id).clean(cx),
 915             deprecation: cx.deprecation(self.id).clean(cx),
 916             def_id: did.to_def_id(),
 917             inner: FunctionItem(Function {
 918                 decl,
 919                 generics,
 920                 header: hir::FnHeader { constness, ..self.header },
 921                 all_types,
 922                 ret_types,
 923             }),
 924         }
 925     }
 926 }
 927
 928 impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], &'a [Ident]) {
 929     fn clean(&self, cx: &DocContext<'_>) -> Arguments {
 930         Arguments {
 931             values: self
 932                 .0
 933                 .iter()
 934                 .enumerate()
 935                 .map(|(i, ty)| {
 936                     let mut name =
 937                         self.1.get(i).map(|ident| ident.to_string()).unwrap_or(String::new());
 938                     if name.is_empty() {
 939                         name = "_".to_string();
 940                     }
 941                     Argument { name, type_: ty.clean(cx) }
 942                 })
 943                 .collect(),
 944         }
 945     }
 946 }
 947
 948 impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], hir::BodyId) {
 949     fn clean(&self, cx: &DocContext<'_>) -> Arguments {
 950         let body = cx.tcx.hir().body(self.1);
 951
 952         Arguments {
 953             values: self
 954                 .0
 955                 .iter()
 956                 .enumerate()
 957                 .map(|(i, ty)| Argument {
 958                     name: name_from_pat(&body.params[i].pat),
 959                     type_: ty.clean(cx),
 960                 })
 961                 .collect(),
 962         }
 963     }
 964 }
 965
 966 impl<'a, A: Copy> Clean<FnDecl> for (&'a hir::FnDecl<'a>, A)
 967 where
 968     (&'a [hir::Ty<'a>], A): Clean<Arguments>,
 969 {
 970     fn clean(&self, cx: &DocContext<'_>) -> FnDecl {
 971         FnDecl {
 972             inputs: (&self.0.inputs[..], self.1).clean(cx),
 973             output: self.0.output.clean(cx),
 974             c_variadic: self.0.c_variadic,
 975             attrs: Attributes::default(),
 976         }
 977     }
 978 }
 979
 980 impl<'tcx> Clean<FnDecl> for (DefId, ty::PolyFnSig<'tcx>) {
 981     fn clean(&self, cx: &DocContext<'_>) -> FnDecl {
 982         let (did, sig) = *self;
 983         let mut names = if did.is_local() { &[] } else { cx.tcx.fn_arg_names(did) }.iter();
 984
 985         FnDecl {
 986             output: Return(sig.skip_binder().output().clean(cx)),
 987             attrs: Attributes::default(),
 988             c_variadic: sig.skip_binder().c_variadic,
 989             inputs: Arguments {
 990                 values: sig
 991                     .skip_binder()
 992                     .inputs()
 993                     .iter()
 994                     .map(|t| Argument {
 995                         type_: t.clean(cx),
 996                         name: names.next().map_or(String::new(), |name| name.to_string()),
 997                     })
 998                     .collect(),
 999             },
1000         }
1001     }
1002 }
1003
1004 impl Clean<FnRetTy> for hir::FnRetTy<'_> {
1005     fn clean(&self, cx: &DocContext<'_>) -> FnRetTy {
1006         match *self {
1007             Self::Return(ref typ) => Return(typ.clean(cx)),
1008             Self::DefaultReturn(..) => DefaultReturn,
1009         }
1010     }
1011 }
1012
1013 impl Clean<Item> for doctree::Trait<'_> {
1014     fn clean(&self, cx: &DocContext<'_>) -> Item {
1015         let attrs = self.attrs.clean(cx);
1016         let is_spotlight = attrs.has_doc_flag(sym::spotlight);
1017         Item {
1018             name: Some(self.name.clean(cx)),
1019             attrs,
1020             source: self.whence.clean(cx),
1021             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
1022             visibility: self.vis.clean(cx),
1023             stability: cx.stability(self.id).clean(cx),
1024             deprecation: cx.deprecation(self.id).clean(cx),
1025             inner: TraitItem(Trait {
1026                 auto: self.is_auto.clean(cx),
1027                 unsafety: self.unsafety,
1028                 items: self.items.iter().map(|ti| ti.clean(cx)).collect(),
1029                 generics: self.generics.clean(cx),
1030                 bounds: self.bounds.clean(cx),
1031                 is_spotlight,
1032                 is_auto: self.is_auto.clean(cx),
1033             }),
1034         }
1035     }
1036 }
1037
1038 impl Clean<Item> for doctree::TraitAlias<'_> {
1039     fn clean(&self, cx: &DocContext<'_>) -> Item {
1040         let attrs = self.attrs.clean(cx);
1041         Item {
1042             name: Some(self.name.clean(cx)),
1043             attrs,
1044             source: self.whence.clean(cx),
1045             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
1046             visibility: self.vis.clean(cx),
1047             stability: cx.stability(self.id).clean(cx),
1048             deprecation: cx.deprecation(self.id).clean(cx),
1049             inner: TraitAliasItem(TraitAlias {
1050                 generics: self.generics.clean(cx),
1051                 bounds: self.bounds.clean(cx),
1052             }),
1053         }
1054     }
1055 }
1056
1057 impl Clean<bool> for hir::IsAuto {
1058     fn clean(&self, _: &DocContext<'_>) -> bool {
1059         match *self {
1060             hir::IsAuto::Yes => true,
1061             hir::IsAuto::No => false,
1062         }
1063     }
1064 }
1065
1066 impl Clean<Type> for hir::TraitRef<'_> {
1067     fn clean(&self, cx: &DocContext<'_>) -> Type {
1068         resolve_type(cx, self.path.clean(cx), self.hir_ref_id)
1069     }
1070 }
1071
1072 impl Clean<PolyTrait> for hir::PolyTraitRef<'_> {
1073     fn clean(&self, cx: &DocContext<'_>) -> PolyTrait {
1074         PolyTrait {
1075             trait_: self.trait_ref.clean(cx),
1076             generic_params: self.bound_generic_params.clean(cx),
1077         }
1078     }
1079 }
1080
1081 impl Clean<TypeKind> for hir::def::DefKind {
1082     fn clean(&self, _: &DocContext<'_>) -> TypeKind {
1083         match *self {
1084             hir::def::DefKind::Mod => TypeKind::Module,
1085             hir::def::DefKind::Struct => TypeKind::Struct,
1086             hir::def::DefKind::Union => TypeKind::Union,
1087             hir::def::DefKind::Enum => TypeKind::Enum,
1088             hir::def::DefKind::Trait => TypeKind::Trait,
1089             hir::def::DefKind::TyAlias => TypeKind::Typedef,
1090             hir::def::DefKind::ForeignTy => TypeKind::Foreign,
1091             hir::def::DefKind::TraitAlias => TypeKind::TraitAlias,
1092             hir::def::DefKind::Fn => TypeKind::Function,
1093             hir::def::DefKind::Const => TypeKind::Const,
1094             hir::def::DefKind::Static => TypeKind::Static,
1095             hir::def::DefKind::Macro(_) => TypeKind::Macro,
1096             _ => TypeKind::Foreign,
1097         }
1098     }
1099 }
1100
1101 impl Clean<Item> for hir::TraitItem<'_> {
1102     fn clean(&self, cx: &DocContext<'_>) -> Item {
1103         let local_did = cx.tcx.hir().local_def_id(self.hir_id);
1104         let inner = match self.kind {
1105             hir::TraitItemKind::Const(ref ty, default) => {
1106                 AssocConstItem(ty.clean(cx), default.map(|e| print_const_expr(cx, e)))
1107             }
1108             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
1109                 let mut m = (sig, &self.generics, body, None).clean(cx);
1110                 if m.header.constness == hir::Constness::Const
1111                     && !is_min_const_fn(cx.tcx, local_did.to_def_id())
1112                 {
1113                     m.header.constness = hir::Constness::NotConst;
1114                 }
1115                 MethodItem(m)
1116             }
1117             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(ref names)) => {
1118                 let (generics, decl) = enter_impl_trait(cx, || {
1119                     (self.generics.clean(cx), (&*sig.decl, &names[..]).clean(cx))
1120                 });
1121                 let (all_types, ret_types) = get_all_types(&generics, &decl, cx);
1122                 let mut t = TyMethod { header: sig.header, decl, generics, all_types, ret_types };
1123                 if t.header.constness == hir::Constness::Const
1124                     && !is_min_const_fn(cx.tcx, local_did.to_def_id())
1125                 {
1126                     t.header.constness = hir::Constness::NotConst;
1127                 }
1128                 TyMethodItem(t)
1129             }
1130             hir::TraitItemKind::Type(ref bounds, ref default) => {
1131                 AssocTypeItem(bounds.clean(cx), default.clean(cx))
1132             }
1133         };
1134         Item {
1135             name: Some(self.ident.name.clean(cx)),
1136             attrs: self.attrs.clean(cx),
1137             source: self.span.clean(cx),
1138             def_id: local_did.to_def_id(),
1139             visibility: Visibility::Inherited,
1140             stability: get_stability(cx, local_did.to_def_id()),
1141             deprecation: get_deprecation(cx, local_did.to_def_id()),
1142             inner,
1143         }
1144     }
1145 }
1146
1147 impl Clean<Item> for hir::ImplItem<'_> {
1148     fn clean(&self, cx: &DocContext<'_>) -> Item {
1149         let local_did = cx.tcx.hir().local_def_id(self.hir_id);
1150         let inner = match self.kind {
1151             hir::ImplItemKind::Const(ref ty, expr) => {
1152                 AssocConstItem(ty.clean(cx), Some(print_const_expr(cx, expr)))
1153             }
1154             hir::ImplItemKind::Fn(ref sig, body) => {
1155                 let mut m = (sig, &self.generics, body, Some(self.defaultness)).clean(cx);
1156                 if m.header.constness == hir::Constness::Const
1157                     && !is_min_const_fn(cx.tcx, local_did.to_def_id())
1158                 {
1159                     m.header.constness = hir::Constness::NotConst;
1160                 }
1161                 MethodItem(m)
1162             }
1163             hir::ImplItemKind::TyAlias(ref ty) => {
1164                 let type_ = ty.clean(cx);
1165                 let item_type = type_.def_id().and_then(|did| inline::build_ty(cx, did));
1166                 TypedefItem(Typedef { type_, generics: Generics::default(), item_type }, true)
1167             }
1168         };
1169         Item {
1170             name: Some(self.ident.name.clean(cx)),
1171             source: self.span.clean(cx),
1172             attrs: self.attrs.clean(cx),
1173             def_id: local_did.to_def_id(),
1174             visibility: self.vis.clean(cx),
1175             stability: get_stability(cx, local_did.to_def_id()),
1176             deprecation: get_deprecation(cx, local_did.to_def_id()),
1177             inner,
1178         }
1179     }
1180 }
1181
1182 impl Clean<Item> for ty::AssocItem {
1183     fn clean(&self, cx: &DocContext<'_>) -> Item {
1184         let inner = match self.kind {
1185             ty::AssocKind::Const => {
1186                 let ty = cx.tcx.type_of(self.def_id);
1187                 let default = if self.defaultness.has_value() {
1188                     Some(inline::print_inlined_const(cx, self.def_id))
1189                 } else {
1190                     None
1191                 };
1192                 AssocConstItem(ty.clean(cx), default)
1193             }
1194             ty::AssocKind::Fn => {
1195                 let generics =
1196                     (cx.tcx.generics_of(self.def_id), cx.tcx.explicit_predicates_of(self.def_id))
1197                         .clean(cx);
1198                 let sig = cx.tcx.fn_sig(self.def_id);
1199                 let mut decl = (self.def_id, sig).clean(cx);
1200
1201                 if self.fn_has_self_parameter {
1202                     let self_ty = match self.container {
1203                         ty::ImplContainer(def_id) => cx.tcx.type_of(def_id),
1204                         ty::TraitContainer(_) => cx.tcx.types.self_param,
1205                     };
1206                     let self_arg_ty = sig.input(0).skip_binder();
1207                     if self_arg_ty == self_ty {
1208                         decl.inputs.values[0].type_ = Generic(String::from("Self"));
1209                     } else if let ty::Ref(_, ty, _) = *self_arg_ty.kind() {
1210                         if ty == self_ty {
1211                             match decl.inputs.values[0].type_ {
1212                                 BorrowedRef { ref mut type_, .. } => {
1213                                     **type_ = Generic(String::from("Self"))
1214                                 }
1215                                 _ => unreachable!(),
1216                             }
1217                         }
1218                     }
1219                 }
1220
1221                 let provided = match self.container {
1222                     ty::ImplContainer(_) => true,
1223                     ty::TraitContainer(_) => self.defaultness.has_value(),
1224                 };
1225                 let (all_types, ret_types) = get_all_types(&generics, &decl, cx);
1226                 if provided {
1227                     let constness = if is_min_const_fn(cx.tcx, self.def_id) {
1228                         hir::Constness::Const
1229                     } else {
1230                         hir::Constness::NotConst
1231                     };
1232                     let asyncness = cx.tcx.asyncness(self.def_id);
1233                     let defaultness = match self.container {
1234                         ty::ImplContainer(_) => Some(self.defaultness),
1235                         ty::TraitContainer(_) => None,
1236                     };
1237                     MethodItem(Method {
1238                         generics,
1239                         decl,
1240                         header: hir::FnHeader {
1241                             unsafety: sig.unsafety(),
1242                             abi: sig.abi(),
1243                             constness,
1244                             asyncness,
1245                         },
1246                         defaultness,
1247                         all_types,
1248                         ret_types,
1249                     })
1250                 } else {
1251                     TyMethodItem(TyMethod {
1252                         generics,
1253                         decl,
1254                         header: hir::FnHeader {
1255                             unsafety: sig.unsafety(),
1256                             abi: sig.abi(),
1257                             constness: hir::Constness::NotConst,
1258                             asyncness: hir::IsAsync::NotAsync,
1259                         },
1260                         all_types,
1261                         ret_types,
1262                     })
1263                 }
1264             }
1265             ty::AssocKind::Type => {
1266                 let my_name = self.ident.name.clean(cx);
1267
1268                 if let ty::TraitContainer(did) = self.container {
1269                     // When loading a cross-crate associated type, the bounds for this type
1270                     // are actually located on the trait/impl itself, so we need to load
1271                     // all of the generics from there and then look for bounds that are
1272                     // applied to this associated type in question.
1273                     let predicates = cx.tcx.explicit_predicates_of(did);
1274                     let generics = (cx.tcx.generics_of(did), predicates).clean(cx);
1275                     let mut bounds = generics
1276                         .where_predicates
1277                         .iter()
1278                         .filter_map(|pred| {
1279                             let (name, self_type, trait_, bounds) = match *pred {
1280                                 WherePredicate::BoundPredicate {
1281                                     ty: QPath { ref name, ref self_type, ref trait_ },
1282                                     ref bounds,
1283                                 } => (name, self_type, trait_, bounds),
1284                                 _ => return None,
1285                             };
1286                             if *name != my_name {
1287                                 return None;
1288                             }
1289                             match **trait_ {
1290                                 ResolvedPath { did, .. } if did == self.container.id() => {}
1291                                 _ => return None,
1292                             }
1293                             match **self_type {
1294                                 Generic(ref s) if *s == "Self" => {}
1295                                 _ => return None,
1296                             }
1297                             Some(bounds)
1298                         })
1299                         .flat_map(|i| i.iter().cloned())
1300                         .collect::<Vec<_>>();
1301                     // Our Sized/?Sized bound didn't get handled when creating the generics
1302                     // because we didn't actually get our whole set of bounds until just now
1303                     // (some of them may have come from the trait). If we do have a sized
1304                     // bound, we remove it, and if we don't then we add the `?Sized` bound
1305                     // at the end.
1306                     match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1307                         Some(i) => {
1308                             bounds.remove(i);
1309                         }
1310                         None => bounds.push(GenericBound::maybe_sized(cx)),
1311                     }
1312
1313                     let ty = if self.defaultness.has_value() {
1314                         Some(cx.tcx.type_of(self.def_id))
1315                     } else {
1316                         None
1317                     };
1318
1319                     AssocTypeItem(bounds, ty.clean(cx))
1320                 } else {
1321                     let type_ = cx.tcx.type_of(self.def_id).clean(cx);
1322                     let item_type = type_.def_id().and_then(|did| inline::build_ty(cx, did));
1323                     TypedefItem(
1324                         Typedef {
1325                             type_,
1326                             generics: Generics { params: Vec::new(), where_predicates: Vec::new() },
1327                             item_type,
1328                         },
1329                         true,
1330                     )
1331                 }
1332             }
1333         };
1334
1335         let visibility = match self.container {
1336             ty::ImplContainer(_) => self.vis.clean(cx),
1337             ty::TraitContainer(_) => Inherited,
1338         };
1339
1340         Item {
1341             name: Some(self.ident.name.clean(cx)),
1342             visibility,
1343             stability: get_stability(cx, self.def_id),
1344             deprecation: get_deprecation(cx, self.def_id),
1345             def_id: self.def_id,
1346             attrs: inline::load_attrs(cx, self.def_id).clean(cx),
1347             source: cx.tcx.def_span(self.def_id).clean(cx),
1348             inner,
1349         }
1350     }
1351 }
1352
1353 impl Clean<Type> for hir::Ty<'_> {
1354     fn clean(&self, cx: &DocContext<'_>) -> Type {
1355         use rustc_hir::*;
1356
1357         match self.kind {
1358             TyKind::Never => Never,
1359             TyKind::Ptr(ref m) => RawPointer(m.mutbl, box m.ty.clean(cx)),
1360             TyKind::Rptr(ref l, ref m) => {
1361                 let lifetime = if l.is_elided() { None } else { Some(l.clean(cx)) };
1362                 BorrowedRef { lifetime, mutability: m.mutbl, type_: box m.ty.clean(cx) }
1363             }
1364             TyKind::Slice(ref ty) => Slice(box ty.clean(cx)),
1365             TyKind::Array(ref ty, ref length) => {
1366                 let def_id = cx.tcx.hir().local_def_id(length.hir_id);
1367                 let length = match cx.tcx.const_eval_poly(def_id.to_def_id()) {
1368                     Ok(length) => {
1369                         print_const(cx, ty::Const::from_value(cx.tcx, length, cx.tcx.types.usize))
1370                     }
1371                     Err(_) => cx
1372                         .sess()
1373                         .source_map()
1374                         .span_to_snippet(cx.tcx.def_span(def_id))
1375                         .unwrap_or_else(|_| "_".to_string()),
1376                 };
1377                 Array(box ty.clean(cx), length)
1378             }
1379             TyKind::Tup(ref tys) => Tuple(tys.clean(cx)),
1380             TyKind::OpaqueDef(item_id, _) => {
1381                 let item = cx.tcx.hir().expect_item(item_id.id);
1382                 if let hir::ItemKind::OpaqueTy(ref ty) = item.kind {
1383                     ImplTrait(ty.bounds.clean(cx))
1384                 } else {
1385                     unreachable!()
1386                 }
1387             }
1388             TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
1389                 if let Res::Def(DefKind::TyParam, did) = path.res {
1390                     if let Some(new_ty) = cx.ty_substs.borrow().get(&did).cloned() {
1391                         return new_ty;
1392                     }
1393                     if let Some(bounds) = cx.impl_trait_bounds.borrow_mut().remove(&did.into()) {
1394                         return ImplTrait(bounds);
1395                     }
1396                 }
1397
1398                 let mut alias = None;
1399                 if let Res::Def(DefKind::TyAlias, def_id) = path.res {
1400                     // Substitute private type aliases
1401                     if let Some(def_id) = def_id.as_local() {
1402                         let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
1403                         if !cx.renderinfo.borrow().access_levels.is_exported(def_id.to_def_id()) {
1404                             alias = Some(&cx.tcx.hir().expect_item(hir_id).kind);
1405                         }
1406                     }
1407                 };
1408
1409                 if let Some(&hir::ItemKind::TyAlias(ref ty, ref generics)) = alias {
1410                     let provided_params = &path.segments.last().expect("segments were empty");
1411                     let mut ty_substs = FxHashMap::default();
1412                     let mut lt_substs = FxHashMap::default();
1413                     let mut ct_substs = FxHashMap::default();
1414                     let generic_args = provided_params.generic_args();
1415                     {
1416                         let mut indices: GenericParamCount = Default::default();
1417                         for param in generics.params.iter() {
1418                             match param.kind {
1419                                 hir::GenericParamKind::Lifetime { .. } => {
1420                                     let mut j = 0;
1421                                     let lifetime =
1422                                         generic_args.args.iter().find_map(|arg| match arg {
1423                                             hir::GenericArg::Lifetime(lt) => {
1424                                                 if indices.lifetimes == j {
1425                                                     return Some(lt);
1426                                                 }
1427                                                 j += 1;
1428                                                 None
1429                                             }
1430                                             _ => None,
1431                                         });
1432                                     if let Some(lt) = lifetime.cloned() {
1433                                         let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1434                                         let cleaned = if !lt.is_elided() {
1435                                             lt.clean(cx)
1436                                         } else {
1437                                             self::types::Lifetime::elided()
1438                                         };
1439                                         lt_substs.insert(lt_def_id.to_def_id(), cleaned);
1440                                     }
1441                                     indices.lifetimes += 1;
1442                                 }
1443                                 hir::GenericParamKind::Type { ref default, .. } => {
1444                                     let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1445                                     let mut j = 0;
1446                                     let type_ =
1447                                         generic_args.args.iter().find_map(|arg| match arg {
1448                                             hir::GenericArg::Type(ty) => {
1449                                                 if indices.types == j {
1450                                                     return Some(ty);
1451                                                 }
1452                                                 j += 1;
1453                                                 None
1454                                             }
1455                                             _ => None,
1456                                         });
1457                                     if let Some(ty) = type_ {
1458                                         ty_substs.insert(ty_param_def_id.to_def_id(), ty.clean(cx));
1459                                     } else if let Some(default) = *default {
1460                                         ty_substs
1461                                             .insert(ty_param_def_id.to_def_id(), default.clean(cx));
1462                                     }
1463                                     indices.types += 1;
1464                                 }
1465                                 hir::GenericParamKind::Const { .. } => {
1466                                     let const_param_def_id =
1467                                         cx.tcx.hir().local_def_id(param.hir_id);
1468                                     let mut j = 0;
1469                                     let const_ =
1470                                         generic_args.args.iter().find_map(|arg| match arg {
1471                                             hir::GenericArg::Const(ct) => {
1472                                                 if indices.consts == j {
1473                                                     return Some(ct);
1474                                                 }
1475                                                 j += 1;
1476                                                 None
1477                                             }
1478                                             _ => None,
1479                                         });
1480                                     if let Some(ct) = const_ {
1481                                         ct_substs
1482                                             .insert(const_param_def_id.to_def_id(), ct.clean(cx));
1483                                     }
1484                                     // FIXME(const_generics:defaults)
1485                                     indices.consts += 1;
1486                                 }
1487                             }
1488                         }
1489                     }
1490                     return cx.enter_alias(ty_substs, lt_substs, ct_substs, || ty.clean(cx));
1491                 }
1492                 resolve_type(cx, path.clean(cx), self.hir_id)
1493             }
1494             TyKind::Path(hir::QPath::Resolved(Some(ref qself), ref p)) => {
1495                 let segments = if p.is_global() { &p.segments[1..] } else { &p.segments };
1496                 let trait_segments = &segments[..segments.len() - 1];
1497                 let trait_path = self::Path {
1498                     global: p.is_global(),
1499                     res: Res::Def(
1500                         DefKind::Trait,
1501                         cx.tcx.associated_item(p.res.def_id()).container.id(),
1502                     ),
1503                     segments: trait_segments.clean(cx),
1504                 };
1505                 Type::QPath {
1506                     name: p.segments.last().expect("segments were empty").ident.name.clean(cx),
1507                     self_type: box qself.clean(cx),
1508                     trait_: box resolve_type(cx, trait_path, self.hir_id),
1509                 }
1510             }
1511             TyKind::Path(hir::QPath::TypeRelative(ref qself, ref segment)) => {
1512                 let mut res = Res::Err;
1513                 let ty = hir_ty_to_ty(cx.tcx, self);
1514                 if let ty::Projection(proj) = ty.kind() {
1515                     res = Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id);
1516                 }
1517                 let trait_path = hir::Path { span: self.span, res, segments: &[] };
1518                 Type::QPath {
1519                     name: segment.ident.name.clean(cx),
1520                     self_type: box qself.clean(cx),
1521                     trait_: box resolve_type(cx, trait_path.clean(cx), self.hir_id),
1522                 }
1523             }
1524             TyKind::Path(hir::QPath::LangItem(..)) => {
1525                 bug!("clean: requiring documentation of lang item")
1526             }
1527             TyKind::TraitObject(ref bounds, ref lifetime) => {
1528                 match bounds[0].clean(cx).trait_ {
1529                     ResolvedPath { path, param_names: None, did, is_generic } => {
1530                         let mut bounds: Vec<self::GenericBound> = bounds[1..]
1531                             .iter()
1532                             .map(|bound| {
1533                                 self::GenericBound::TraitBound(
1534                                     bound.clean(cx),
1535                                     hir::TraitBoundModifier::None,
1536                                 )
1537                             })
1538                             .collect();
1539                         if !lifetime.is_elided() {
1540                             bounds.push(self::GenericBound::Outlives(lifetime.clean(cx)));
1541                         }
1542                         ResolvedPath { path, param_names: Some(bounds), did, is_generic }
1543                     }
1544                     _ => Infer, // shouldn't happen
1545                 }
1546             }
1547             TyKind::BareFn(ref barefn) => BareFunction(box barefn.clean(cx)),
1548             TyKind::Infer | TyKind::Err => Infer,
1549             TyKind::Typeof(..) => panic!("unimplemented type {:?}", self.kind),
1550         }
1551     }
1552 }
1553
1554 impl<'tcx> Clean<Type> for Ty<'tcx> {
1555     fn clean(&self, cx: &DocContext<'_>) -> Type {
1556         debug!("cleaning type: {:?}", self);
1557         match *self.kind() {
1558             ty::Never => Never,
1559             ty::Bool => Primitive(PrimitiveType::Bool),
1560             ty::Char => Primitive(PrimitiveType::Char),
1561             ty::Int(int_ty) => Primitive(int_ty.into()),
1562             ty::Uint(uint_ty) => Primitive(uint_ty.into()),
1563             ty::Float(float_ty) => Primitive(float_ty.into()),
1564             ty::Str => Primitive(PrimitiveType::Str),
1565             ty::Slice(ty) => Slice(box ty.clean(cx)),
1566             ty::Array(ty, n) => {
1567                 let mut n = cx.tcx.lift(&n).expect("array lift failed");
1568                 n = n.eval(cx.tcx, ty::ParamEnv::reveal_all());
1569                 let n = print_const(cx, n);
1570                 Array(box ty.clean(cx), n)
1571             }
1572             ty::RawPtr(mt) => RawPointer(mt.mutbl, box mt.ty.clean(cx)),
1573             ty::Ref(r, ty, mutbl) => {
1574                 BorrowedRef { lifetime: r.clean(cx), mutability: mutbl, type_: box ty.clean(cx) }
1575             }
1576             ty::FnDef(..) | ty::FnPtr(_) => {
1577                 let ty = cx.tcx.lift(self).expect("FnPtr lift failed");
1578                 let sig = ty.fn_sig(cx.tcx);
1579                 let def_id = DefId::local(CRATE_DEF_INDEX);
1580                 BareFunction(box BareFunctionDecl {
1581                     unsafety: sig.unsafety(),
1582                     generic_params: Vec::new(),
1583                     decl: (def_id, sig).clean(cx),
1584                     abi: sig.abi(),
1585                 })
1586             }
1587             ty::Adt(def, substs) => {
1588                 let did = def.did;
1589                 let kind = match def.adt_kind() {
1590                     AdtKind::Struct => TypeKind::Struct,
1591                     AdtKind::Union => TypeKind::Union,
1592                     AdtKind::Enum => TypeKind::Enum,
1593                 };
1594                 inline::record_extern_fqn(cx, did, kind);
1595                 let path = external_path(cx, cx.tcx.item_name(did), None, false, vec![], substs);
1596                 ResolvedPath { path, param_names: None, did, is_generic: false }
1597             }
1598             ty::Foreign(did) => {
1599                 inline::record_extern_fqn(cx, did, TypeKind::Foreign);
1600                 let path = external_path(
1601                     cx,
1602                     cx.tcx.item_name(did),
1603                     None,
1604                     false,
1605                     vec![],
1606                     InternalSubsts::empty(),
1607                 );
1608                 ResolvedPath { path, param_names: None, did, is_generic: false }
1609             }
1610             ty::Dynamic(ref obj, ref reg) => {
1611                 // HACK: pick the first `did` as the `did` of the trait object. Someone
1612                 // might want to implement "native" support for marker-trait-only
1613                 // trait objects.
1614                 let mut dids = obj.principal_def_id().into_iter().chain(obj.auto_traits());
1615                 let did = dids
1616                     .next()
1617                     .unwrap_or_else(|| panic!("found trait object `{:?}` with no traits?", self));
1618                 let substs = match obj.principal() {
1619                     Some(principal) => principal.skip_binder().substs,
1620                     // marker traits have no substs.
1621                     _ => cx.tcx.intern_substs(&[]),
1622                 };
1623
1624                 inline::record_extern_fqn(cx, did, TypeKind::Trait);
1625
1626                 let mut param_names = vec![];
1627                 if let Some(b) = reg.clean(cx) {
1628                     param_names.push(GenericBound::Outlives(b));
1629                 }
1630                 for did in dids {
1631                     let empty = cx.tcx.intern_substs(&[]);
1632                     let path =
1633                         external_path(cx, cx.tcx.item_name(did), Some(did), false, vec![], empty);
1634                     inline::record_extern_fqn(cx, did, TypeKind::Trait);
1635                     let bound = GenericBound::TraitBound(
1636                         PolyTrait {
1637                             trait_: ResolvedPath {
1638                                 path,
1639                                 param_names: None,
1640                                 did,
1641                                 is_generic: false,
1642                             },
1643                             generic_params: Vec::new(),
1644                         },
1645                         hir::TraitBoundModifier::None,
1646                     );
1647                     param_names.push(bound);
1648                 }
1649
1650                 let mut bindings = vec![];
1651                 for pb in obj.projection_bounds() {
1652                     bindings.push(TypeBinding {
1653                         name: cx.tcx.associated_item(pb.item_def_id()).ident.name.clean(cx),
1654                         kind: TypeBindingKind::Equality { ty: pb.skip_binder().ty.clean(cx) },
1655                     });
1656                 }
1657
1658                 let path =
1659                     external_path(cx, cx.tcx.item_name(did), Some(did), false, bindings, substs);
1660                 ResolvedPath { path, param_names: Some(param_names), did, is_generic: false }
1661             }
1662             ty::Tuple(ref t) => {
1663                 Tuple(t.iter().map(|t| t.expect_ty()).collect::<Vec<_>>().clean(cx))
1664             }
1665
1666             ty::Projection(ref data) => data.clean(cx),
1667
1668             ty::Param(ref p) => {
1669                 if let Some(bounds) = cx.impl_trait_bounds.borrow_mut().remove(&p.index.into()) {
1670                     ImplTrait(bounds)
1671                 } else {
1672                     Generic(p.name.to_string())
1673                 }
1674             }
1675
1676             ty::Opaque(def_id, substs) => {
1677                 // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1678                 // by looking up the projections associated with the def_id.
1679                 let predicates_of = cx.tcx.explicit_predicates_of(def_id);
1680                 let substs = cx.tcx.lift(&substs).expect("Opaque lift failed");
1681                 let bounds = predicates_of.instantiate(cx.tcx, substs);
1682                 let mut regions = vec![];
1683                 let mut has_sized = false;
1684                 let mut bounds = bounds
1685                     .predicates
1686                     .iter()
1687                     .filter_map(|predicate| {
1688                         // Note: The substs of opaque types can contain unbound variables,
1689                         // meaning that we have to use `ignore_quantifiers_with_unbound_vars` here.
1690                         let trait_ref = match predicate.bound_atom(cx.tcx).skip_binder() {
1691                             ty::PredicateAtom::Trait(tr, _constness) => {
1692                                 ty::Binder::bind(tr.trait_ref)
1693                             }
1694                             ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
1695                                 if let Some(r) = reg.clean(cx) {
1696                                     regions.push(GenericBound::Outlives(r));
1697                                 }
1698                                 return None;
1699                             }
1700                             _ => return None,
1701                         };
1702
1703                         if let Some(sized) = cx.tcx.lang_items().sized_trait() {
1704                             if trait_ref.def_id() == sized {
1705                                 has_sized = true;
1706                                 return None;
1707                             }
1708                         }
1709
1710                         let bounds: Vec<_> = bounds
1711                             .predicates
1712                             .iter()
1713                             .filter_map(|pred| {
1714                                 if let ty::PredicateAtom::Projection(proj) =
1715                                     pred.bound_atom(cx.tcx).skip_binder()
1716                                 {
1717                                     if proj.projection_ty.trait_ref(cx.tcx)
1718                                         == trait_ref.skip_binder()
1719                                     {
1720                                         Some(TypeBinding {
1721                                             name: cx
1722                                                 .tcx
1723                                                 .associated_item(proj.projection_ty.item_def_id)
1724                                                 .ident
1725                                                 .name
1726                                                 .clean(cx),
1727                                             kind: TypeBindingKind::Equality {
1728                                                 ty: proj.ty.clean(cx),
1729                                             },
1730                                         })
1731                                     } else {
1732                                         None
1733                                     }
1734                                 } else {
1735                                     None
1736                                 }
1737                             })
1738                             .collect();
1739
1740                         Some((trait_ref, &bounds[..]).clean(cx))
1741                     })
1742                     .collect::<Vec<_>>();
1743                 bounds.extend(regions);
1744                 if !has_sized && !bounds.is_empty() {
1745                     bounds.insert(0, GenericBound::maybe_sized(cx));
1746                 }
1747                 ImplTrait(bounds)
1748             }
1749
1750             ty::Closure(..) | ty::Generator(..) => Tuple(vec![]), // FIXME(pcwalton)
1751
1752             ty::Bound(..) => panic!("Bound"),
1753             ty::Placeholder(..) => panic!("Placeholder"),
1754             ty::GeneratorWitness(..) => panic!("GeneratorWitness"),
1755             ty::Infer(..) => panic!("Infer"),
1756             ty::Error(_) => panic!("Error"),
1757         }
1758     }
1759 }
1760
1761 impl<'tcx> Clean<Constant> for ty::Const<'tcx> {
1762     fn clean(&self, cx: &DocContext<'_>) -> Constant {
1763         Constant {
1764             type_: self.ty.clean(cx),
1765             expr: format!("{}", self),
1766             value: None,
1767             is_literal: false,
1768         }
1769     }
1770 }
1771
1772 impl Clean<Item> for hir::StructField<'_> {
1773     fn clean(&self, cx: &DocContext<'_>) -> Item {
1774         let local_did = cx.tcx.hir().local_def_id(self.hir_id);
1775
1776         Item {
1777             name: Some(self.ident.name).clean(cx),
1778             attrs: self.attrs.clean(cx),
1779             source: self.span.clean(cx),
1780             visibility: self.vis.clean(cx),
1781             stability: get_stability(cx, local_did.to_def_id()),
1782             deprecation: get_deprecation(cx, local_did.to_def_id()),
1783             def_id: local_did.to_def_id(),
1784             inner: StructFieldItem(self.ty.clean(cx)),
1785         }
1786     }
1787 }
1788
1789 impl Clean<Item> for ty::FieldDef {
1790     fn clean(&self, cx: &DocContext<'_>) -> Item {
1791         Item {
1792             name: Some(self.ident.name).clean(cx),
1793             attrs: cx.tcx.get_attrs(self.did).clean(cx),
1794             source: cx.tcx.def_span(self.did).clean(cx),
1795             visibility: self.vis.clean(cx),
1796             stability: get_stability(cx, self.did),
1797             deprecation: get_deprecation(cx, self.did),
1798             def_id: self.did,
1799             inner: StructFieldItem(cx.tcx.type_of(self.did).clean(cx)),
1800         }
1801     }
1802 }
1803
1804 impl Clean<Visibility> for hir::Visibility<'_> {
1805     fn clean(&self, cx: &DocContext<'_>) -> Visibility {
1806         match self.node {
1807             hir::VisibilityKind::Public => Visibility::Public,
1808             hir::VisibilityKind::Inherited => Visibility::Inherited,
1809             hir::VisibilityKind::Crate(_) => Visibility::Crate,
1810             hir::VisibilityKind::Restricted { ref path, .. } => {
1811                 let path = path.clean(cx);
1812                 let did = register_res(cx, path.res);
1813                 Visibility::Restricted(did, path)
1814             }
1815         }
1816     }
1817 }
1818
1819 impl Clean<Visibility> for ty::Visibility {
1820     fn clean(&self, _: &DocContext<'_>) -> Visibility {
1821         if *self == ty::Visibility::Public { Public } else { Inherited }
1822     }
1823 }
1824
1825 impl Clean<Item> for doctree::Struct<'_> {
1826     fn clean(&self, cx: &DocContext<'_>) -> Item {
1827         Item {
1828             name: Some(self.name.clean(cx)),
1829             attrs: self.attrs.clean(cx),
1830             source: self.whence.clean(cx),
1831             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
1832             visibility: self.vis.clean(cx),
1833             stability: cx.stability(self.id).clean(cx),
1834             deprecation: cx.deprecation(self.id).clean(cx),
1835             inner: StructItem(Struct {
1836                 struct_type: self.struct_type,
1837                 generics: self.generics.clean(cx),
1838                 fields: self.fields.clean(cx),
1839                 fields_stripped: false,
1840             }),
1841         }
1842     }
1843 }
1844
1845 impl Clean<Item> for doctree::Union<'_> {
1846     fn clean(&self, cx: &DocContext<'_>) -> Item {
1847         Item {
1848             name: Some(self.name.clean(cx)),
1849             attrs: self.attrs.clean(cx),
1850             source: self.whence.clean(cx),
1851             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
1852             visibility: self.vis.clean(cx),
1853             stability: cx.stability(self.id).clean(cx),
1854             deprecation: cx.deprecation(self.id).clean(cx),
1855             inner: UnionItem(Union {
1856                 struct_type: self.struct_type,
1857                 generics: self.generics.clean(cx),
1858                 fields: self.fields.clean(cx),
1859                 fields_stripped: false,
1860             }),
1861         }
1862     }
1863 }
1864
1865 impl Clean<VariantStruct> for rustc_hir::VariantData<'_> {
1866     fn clean(&self, cx: &DocContext<'_>) -> VariantStruct {
1867         VariantStruct {
1868             struct_type: doctree::struct_type_from_def(self),
1869             fields: self.fields().iter().map(|x| x.clean(cx)).collect(),
1870             fields_stripped: false,
1871         }
1872     }
1873 }
1874
1875 impl Clean<Item> for doctree::Enum<'_> {
1876     fn clean(&self, cx: &DocContext<'_>) -> Item {
1877         Item {
1878             name: Some(self.name.clean(cx)),
1879             attrs: self.attrs.clean(cx),
1880             source: self.whence.clean(cx),
1881             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
1882             visibility: self.vis.clean(cx),
1883             stability: cx.stability(self.id).clean(cx),
1884             deprecation: cx.deprecation(self.id).clean(cx),
1885             inner: EnumItem(Enum {
1886                 variants: self.variants.iter().map(|v| v.clean(cx)).collect(),
1887                 generics: self.generics.clean(cx),
1888                 variants_stripped: false,
1889             }),
1890         }
1891     }
1892 }
1893
1894 impl Clean<Item> for doctree::Variant<'_> {
1895     fn clean(&self, cx: &DocContext<'_>) -> Item {
1896         Item {
1897             name: Some(self.name.clean(cx)),
1898             attrs: self.attrs.clean(cx),
1899             source: self.whence.clean(cx),
1900             visibility: Inherited,
1901             stability: cx.stability(self.id).clean(cx),
1902             deprecation: cx.deprecation(self.id).clean(cx),
1903             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
1904             inner: VariantItem(Variant { kind: self.def.clean(cx) }),
1905         }
1906     }
1907 }
1908
1909 impl Clean<Item> for ty::VariantDef {
1910     fn clean(&self, cx: &DocContext<'_>) -> Item {
1911         let kind = match self.ctor_kind {
1912             CtorKind::Const => VariantKind::CLike,
1913             CtorKind::Fn => VariantKind::Tuple(
1914                 self.fields.iter().map(|f| cx.tcx.type_of(f.did).clean(cx)).collect(),
1915             ),
1916             CtorKind::Fictive => VariantKind::Struct(VariantStruct {
1917                 struct_type: doctree::Plain,
1918                 fields_stripped: false,
1919                 fields: self
1920                     .fields
1921                     .iter()
1922                     .map(|field| Item {
1923                         source: cx.tcx.def_span(field.did).clean(cx),
1924                         name: Some(field.ident.name.clean(cx)),
1925                         attrs: cx.tcx.get_attrs(field.did).clean(cx),
1926                         visibility: field.vis.clean(cx),
1927                         def_id: field.did,
1928                         stability: get_stability(cx, field.did),
1929                         deprecation: get_deprecation(cx, field.did),
1930                         inner: StructFieldItem(cx.tcx.type_of(field.did).clean(cx)),
1931                     })
1932                     .collect(),
1933             }),
1934         };
1935         Item {
1936             name: Some(self.ident.clean(cx)),
1937             attrs: inline::load_attrs(cx, self.def_id).clean(cx),
1938             source: cx.tcx.def_span(self.def_id).clean(cx),
1939             visibility: Inherited,
1940             def_id: self.def_id,
1941             inner: VariantItem(Variant { kind }),
1942             stability: get_stability(cx, self.def_id),
1943             deprecation: get_deprecation(cx, self.def_id),
1944         }
1945     }
1946 }
1947
1948 impl Clean<VariantKind> for hir::VariantData<'_> {
1949     fn clean(&self, cx: &DocContext<'_>) -> VariantKind {
1950         match self {
1951             hir::VariantData::Struct(..) => VariantKind::Struct(self.clean(cx)),
1952             hir::VariantData::Tuple(..) => {
1953                 VariantKind::Tuple(self.fields().iter().map(|x| x.ty.clean(cx)).collect())
1954             }
1955             hir::VariantData::Unit(..) => VariantKind::CLike,
1956         }
1957     }
1958 }
1959
1960 impl Clean<Span> for rustc_span::Span {
1961     fn clean(&self, cx: &DocContext<'_>) -> Span {
1962         if self.is_dummy() {
1963             return Span::empty();
1964         }
1965
1966         let sm = cx.sess().source_map();
1967         let filename = sm.span_to_filename(*self);
1968         let lo = sm.lookup_char_pos(self.lo());
1969         let hi = sm.lookup_char_pos(self.hi());
1970         Span {
1971             filename,
1972             cnum: lo.file.cnum,
1973             loline: lo.line,
1974             locol: lo.col.to_usize(),
1975             hiline: hi.line,
1976             hicol: hi.col.to_usize(),
1977             original: *self,
1978         }
1979     }
1980 }
1981
1982 impl Clean<Path> for hir::Path<'_> {
1983     fn clean(&self, cx: &DocContext<'_>) -> Path {
1984         Path {
1985             global: self.is_global(),
1986             res: self.res,
1987             segments: if self.is_global() { &self.segments[1..] } else { &self.segments }.clean(cx),
1988         }
1989     }
1990 }
1991
1992 impl Clean<GenericArgs> for hir::GenericArgs<'_> {
1993     fn clean(&self, cx: &DocContext<'_>) -> GenericArgs {
1994         if self.parenthesized {
1995             let output = self.bindings[0].ty().clean(cx);
1996             GenericArgs::Parenthesized {
1997                 inputs: self.inputs().clean(cx),
1998                 output: if output != Type::Tuple(Vec::new()) { Some(output) } else { None },
1999             }
2000         } else {
2001             GenericArgs::AngleBracketed {
2002                 args: self
2003                     .args
2004                     .iter()
2005                     .map(|arg| match arg {
2006                         hir::GenericArg::Lifetime(lt) if !lt.is_elided() => {
2007                             GenericArg::Lifetime(lt.clean(cx))
2008                         }
2009                         hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
2010                         hir::GenericArg::Type(ty) => GenericArg::Type(ty.clean(cx)),
2011                         hir::GenericArg::Const(ct) => GenericArg::Const(ct.clean(cx)),
2012                     })
2013                     .collect(),
2014                 bindings: self.bindings.clean(cx),
2015             }
2016         }
2017     }
2018 }
2019
2020 impl Clean<PathSegment> for hir::PathSegment<'_> {
2021     fn clean(&self, cx: &DocContext<'_>) -> PathSegment {
2022         PathSegment { name: self.ident.name.clean(cx), args: self.generic_args().clean(cx) }
2023     }
2024 }
2025
2026 impl Clean<String> for Ident {
2027     #[inline]
2028     fn clean(&self, cx: &DocContext<'_>) -> String {
2029         self.name.clean(cx)
2030     }
2031 }
2032
2033 impl Clean<String> for Symbol {
2034     #[inline]
2035     fn clean(&self, _: &DocContext<'_>) -> String {
2036         self.to_string()
2037     }
2038 }
2039
2040 impl Clean<Item> for doctree::Typedef<'_> {
2041     fn clean(&self, cx: &DocContext<'_>) -> Item {
2042         let type_ = self.ty.clean(cx);
2043         let item_type = type_.def_id().and_then(|did| inline::build_ty(cx, did));
2044         Item {
2045             name: Some(self.name.clean(cx)),
2046             attrs: self.attrs.clean(cx),
2047             source: self.whence.clean(cx),
2048             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
2049             visibility: self.vis.clean(cx),
2050             stability: cx.stability(self.id).clean(cx),
2051             deprecation: cx.deprecation(self.id).clean(cx),
2052             inner: TypedefItem(Typedef { type_, generics: self.gen.clean(cx), item_type }, false),
2053         }
2054     }
2055 }
2056
2057 impl Clean<Item> for doctree::OpaqueTy<'_> {
2058     fn clean(&self, cx: &DocContext<'_>) -> Item {
2059         Item {
2060             name: Some(self.name.clean(cx)),
2061             attrs: self.attrs.clean(cx),
2062             source: self.whence.clean(cx),
2063             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
2064             visibility: self.vis.clean(cx),
2065             stability: cx.stability(self.id).clean(cx),
2066             deprecation: cx.deprecation(self.id).clean(cx),
2067             inner: OpaqueTyItem(
2068                 OpaqueTy {
2069                     bounds: self.opaque_ty.bounds.clean(cx),
2070                     generics: self.opaque_ty.generics.clean(cx),
2071                 },
2072                 false,
2073             ),
2074         }
2075     }
2076 }
2077
2078 impl Clean<BareFunctionDecl> for hir::BareFnTy<'_> {
2079     fn clean(&self, cx: &DocContext<'_>) -> BareFunctionDecl {
2080         let (generic_params, decl) = enter_impl_trait(cx, || {
2081             (self.generic_params.clean(cx), (&*self.decl, &self.param_names[..]).clean(cx))
2082         });
2083         BareFunctionDecl { unsafety: self.unsafety, abi: self.abi, decl, generic_params }
2084     }
2085 }
2086
2087 impl Clean<Item> for doctree::Static<'_> {
2088     fn clean(&self, cx: &DocContext<'_>) -> Item {
2089         debug!("cleaning static {}: {:?}", self.name.clean(cx), self);
2090         Item {
2091             name: Some(self.name.clean(cx)),
2092             attrs: self.attrs.clean(cx),
2093             source: self.whence.clean(cx),
2094             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
2095             visibility: self.vis.clean(cx),
2096             stability: cx.stability(self.id).clean(cx),
2097             deprecation: cx.deprecation(self.id).clean(cx),
2098             inner: StaticItem(Static {
2099                 type_: self.type_.clean(cx),
2100                 mutability: self.mutability,
2101                 expr: print_const_expr(cx, self.expr),
2102             }),
2103         }
2104     }
2105 }
2106
2107 impl Clean<Item> for doctree::Constant<'_> {
2108     fn clean(&self, cx: &DocContext<'_>) -> Item {
2109         let def_id = cx.tcx.hir().local_def_id(self.id);
2110
2111         Item {
2112             name: Some(self.name.clean(cx)),
2113             attrs: self.attrs.clean(cx),
2114             source: self.whence.clean(cx),
2115             def_id: def_id.to_def_id(),
2116             visibility: self.vis.clean(cx),
2117             stability: cx.stability(self.id).clean(cx),
2118             deprecation: cx.deprecation(self.id).clean(cx),
2119             inner: ConstantItem(Constant {
2120                 type_: self.type_.clean(cx),
2121                 expr: print_const_expr(cx, self.expr),
2122                 value: print_evaluated_const(cx, def_id.to_def_id()),
2123                 is_literal: is_literal_expr(cx, self.expr.hir_id),
2124             }),
2125         }
2126     }
2127 }
2128
2129 impl Clean<ImplPolarity> for ty::ImplPolarity {
2130     fn clean(&self, _: &DocContext<'_>) -> ImplPolarity {
2131         match self {
2132             &ty::ImplPolarity::Positive |
2133             // FIXME: do we want to do something else here?
2134             &ty::ImplPolarity::Reservation => ImplPolarity::Positive,
2135             &ty::ImplPolarity::Negative => ImplPolarity::Negative,
2136         }
2137     }
2138 }
2139
2140 impl Clean<Vec<Item>> for doctree::Impl<'_> {
2141     fn clean(&self, cx: &DocContext<'_>) -> Vec<Item> {
2142         let mut ret = Vec::new();
2143         let trait_ = self.trait_.clean(cx);
2144         let items = self.items.iter().map(|ii| ii.clean(cx)).collect::<Vec<_>>();
2145         let def_id = cx.tcx.hir().local_def_id(self.id);
2146
2147         // If this impl block is an implementation of the Deref trait, then we
2148         // need to try inlining the target's inherent impl blocks as well.
2149         if trait_.def_id() == cx.tcx.lang_items().deref_trait() {
2150             build_deref_target_impls(cx, &items, &mut ret);
2151         }
2152
2153         let provided: FxHashSet<String> = trait_
2154             .def_id()
2155             .map(|did| {
2156                 cx.tcx.provided_trait_methods(did).map(|meth| meth.ident.to_string()).collect()
2157             })
2158             .unwrap_or_default();
2159
2160         let for_ = self.for_.clean(cx);
2161         let type_alias = for_.def_id().and_then(|did| match cx.tcx.def_kind(did) {
2162             DefKind::TyAlias => Some(cx.tcx.type_of(did).clean(cx)),
2163             _ => None,
2164         });
2165         let make_item = |trait_: Option<Type>, for_: Type, items: Vec<Item>| Item {
2166             name: None,
2167             attrs: self.attrs.clean(cx),
2168             source: self.whence.clean(cx),
2169             def_id: def_id.to_def_id(),
2170             visibility: self.vis.clean(cx),
2171             stability: cx.stability(self.id).clean(cx),
2172             deprecation: cx.deprecation(self.id).clean(cx),
2173             inner: ImplItem(Impl {
2174                 unsafety: self.unsafety,
2175                 generics: self.generics.clean(cx),
2176                 provided_trait_methods: provided.clone(),
2177                 trait_,
2178                 for_,
2179                 items,
2180                 polarity: Some(cx.tcx.impl_polarity(def_id).clean(cx)),
2181                 synthetic: false,
2182                 blanket_impl: None,
2183             }),
2184         };
2185         if let Some(type_alias) = type_alias {
2186             ret.push(make_item(trait_.clone(), type_alias, items.clone()));
2187         }
2188         ret.push(make_item(trait_, for_, items));
2189         ret
2190     }
2191 }
2192
2193 impl Clean<Vec<Item>> for doctree::ExternCrate<'_> {
2194     fn clean(&self, cx: &DocContext<'_>) -> Vec<Item> {
2195         let please_inline = self.vis.node.is_pub()
2196             && self.attrs.iter().any(|a| {
2197                 a.has_name(sym::doc)
2198                     && match a.meta_item_list() {
2199                         Some(l) => attr::list_contains_name(&l, sym::inline),
2200                         None => false,
2201                     }
2202             });
2203
2204         if please_inline {
2205             let mut visited = FxHashSet::default();
2206
2207             let res = Res::Def(DefKind::Mod, DefId { krate: self.cnum, index: CRATE_DEF_INDEX });
2208
2209             if let Some(items) =
2210                 inline::try_inline(cx, res, self.name, Some(self.attrs), &mut visited)
2211             {
2212                 return items;
2213             }
2214         }
2215
2216         vec![Item {
2217             name: None,
2218             attrs: self.attrs.clean(cx),
2219             source: self.whence.clean(cx),
2220             def_id: DefId { krate: self.cnum, index: CRATE_DEF_INDEX },
2221             visibility: self.vis.clean(cx),
2222             stability: None,
2223             deprecation: None,
2224             inner: ExternCrateItem(self.name.clean(cx), self.path.clone()),
2225         }]
2226     }
2227 }
2228
2229 impl Clean<Vec<Item>> for doctree::Import<'_> {
2230     fn clean(&self, cx: &DocContext<'_>) -> Vec<Item> {
2231         // We consider inlining the documentation of `pub use` statements, but we
2232         // forcefully don't inline if this is not public or if the
2233         // #[doc(no_inline)] attribute is present.
2234         // Don't inline doc(hidden) imports so they can be stripped at a later stage.
2235         let mut denied = !self.vis.node.is_pub()
2236             || self.attrs.iter().any(|a| {
2237                 a.has_name(sym::doc)
2238                     && match a.meta_item_list() {
2239                         Some(l) => {
2240                             attr::list_contains_name(&l, sym::no_inline)
2241                                 || attr::list_contains_name(&l, sym::hidden)
2242                         }
2243                         None => false,
2244                     }
2245             });
2246         // Also check whether imports were asked to be inlined, in case we're trying to re-export a
2247         // crate in Rust 2018+
2248         let please_inline = self.attrs.lists(sym::doc).has_word(sym::inline);
2249         let path = self.path.clean(cx);
2250         let inner = if self.glob {
2251             if !denied {
2252                 let mut visited = FxHashSet::default();
2253                 if let Some(items) = inline::try_inline_glob(cx, path.res, &mut visited) {
2254                     return items;
2255                 }
2256             }
2257
2258             Import::Glob(resolve_use_source(cx, path))
2259         } else {
2260             let name = self.name;
2261             if !please_inline {
2262                 if let Res::Def(DefKind::Mod, did) = path.res {
2263                     if !did.is_local() && did.index == CRATE_DEF_INDEX {
2264                         // if we're `pub use`ing an extern crate root, don't inline it unless we
2265                         // were specifically asked for it
2266                         denied = true;
2267                     }
2268                 }
2269             }
2270             if !denied {
2271                 let mut visited = FxHashSet::default();
2272                 if let Some(items) =
2273                     inline::try_inline(cx, path.res, name, Some(self.attrs), &mut visited)
2274                 {
2275                     return items;
2276                 }
2277             }
2278             Import::Simple(name.clean(cx), resolve_use_source(cx, path))
2279         };
2280
2281         vec![Item {
2282             name: None,
2283             attrs: self.attrs.clean(cx),
2284             source: self.whence.clean(cx),
2285             def_id: DefId::local(CRATE_DEF_INDEX),
2286             visibility: self.vis.clean(cx),
2287             stability: None,
2288             deprecation: None,
2289             inner: ImportItem(inner),
2290         }]
2291     }
2292 }
2293
2294 impl Clean<Item> for doctree::ForeignItem<'_> {
2295     fn clean(&self, cx: &DocContext<'_>) -> Item {
2296         let inner = match self.kind {
2297             hir::ForeignItemKind::Fn(ref decl, ref names, ref generics) => {
2298                 let abi = cx.tcx.hir().get_foreign_abi(self.id);
2299                 let (generics, decl) =
2300                     enter_impl_trait(cx, || (generics.clean(cx), (&**decl, &names[..]).clean(cx)));
2301                 let (all_types, ret_types) = get_all_types(&generics, &decl, cx);
2302                 ForeignFunctionItem(Function {
2303                     decl,
2304                     generics,
2305                     header: hir::FnHeader {
2306                         unsafety: hir::Unsafety::Unsafe,
2307                         abi,
2308                         constness: hir::Constness::NotConst,
2309                         asyncness: hir::IsAsync::NotAsync,
2310                     },
2311                     all_types,
2312                     ret_types,
2313                 })
2314             }
2315             hir::ForeignItemKind::Static(ref ty, mutbl) => ForeignStaticItem(Static {
2316                 type_: ty.clean(cx),
2317                 mutability: *mutbl,
2318                 expr: String::new(),
2319             }),
2320             hir::ForeignItemKind::Type => ForeignTypeItem,
2321         };
2322
2323         Item {
2324             name: Some(self.name.clean(cx)),
2325             attrs: self.attrs.clean(cx),
2326             source: self.whence.clean(cx),
2327             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
2328             visibility: self.vis.clean(cx),
2329             stability: cx.stability(self.id).clean(cx),
2330             deprecation: cx.deprecation(self.id).clean(cx),
2331             inner,
2332         }
2333     }
2334 }
2335
2336 impl Clean<Item> for doctree::Macro<'_> {
2337     fn clean(&self, cx: &DocContext<'_>) -> Item {
2338         let name = self.name.clean(cx);
2339         Item {
2340             name: Some(name.clone()),
2341             attrs: self.attrs.clean(cx),
2342             source: self.whence.clean(cx),
2343             visibility: Public,
2344             stability: cx.stability(self.hid).clean(cx),
2345             deprecation: cx.deprecation(self.hid).clean(cx),
2346             def_id: self.def_id,
2347             inner: MacroItem(Macro {
2348                 source: format!(
2349                     "macro_rules! {} {{\n{}}}",
2350                     name,
2351                     self.matchers
2352                         .iter()
2353                         .map(|span| { format!("    {} => {{ ... }};\n", span.to_src(cx)) })
2354                         .collect::<String>()
2355                 ),
2356                 imported_from: self.imported_from.clean(cx),
2357             }),
2358         }
2359     }
2360 }
2361
2362 impl Clean<Item> for doctree::ProcMacro<'_> {
2363     fn clean(&self, cx: &DocContext<'_>) -> Item {
2364         Item {
2365             name: Some(self.name.clean(cx)),
2366             attrs: self.attrs.clean(cx),
2367             source: self.whence.clean(cx),
2368             visibility: Public,
2369             stability: cx.stability(self.id).clean(cx),
2370             deprecation: cx.deprecation(self.id).clean(cx),
2371             def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
2372             inner: ProcMacroItem(ProcMacro { kind: self.kind, helpers: self.helpers.clean(cx) }),
2373         }
2374     }
2375 }
2376
2377 impl Clean<Stability> for attr::Stability {
2378     fn clean(&self, _: &DocContext<'_>) -> Stability {
2379         Stability {
2380             level: stability::StabilityLevel::from_attr_level(&self.level),
2381             feature: self.feature.to_string(),
2382             since: match self.level {
2383                 attr::Stable { ref since } => since.to_string(),
2384                 _ => String::new(),
2385             },
2386             unstable_reason: match self.level {
2387                 attr::Unstable { reason: Some(ref reason), .. } => Some(reason.to_string()),
2388                 _ => None,
2389             },
2390             issue: match self.level {
2391                 attr::Unstable { issue, .. } => issue,
2392                 _ => None,
2393             },
2394         }
2395     }
2396 }
2397
2398 impl Clean<Deprecation> for attr::Deprecation {
2399     fn clean(&self, _: &DocContext<'_>) -> Deprecation {
2400         Deprecation {
2401             since: self.since.map(|s| s.to_string()).filter(|s| !s.is_empty()),
2402             note: self.note.map(|n| n.to_string()).filter(|n| !n.is_empty()),
2403             is_since_rustc_version: self.is_since_rustc_version,
2404         }
2405     }
2406 }
2407
2408 impl Clean<TypeBinding> for hir::TypeBinding<'_> {
2409     fn clean(&self, cx: &DocContext<'_>) -> TypeBinding {
2410         TypeBinding { name: self.ident.name.clean(cx), kind: self.kind.clean(cx) }
2411     }
2412 }
2413
2414 impl Clean<TypeBindingKind> for hir::TypeBindingKind<'_> {
2415     fn clean(&self, cx: &DocContext<'_>) -> TypeBindingKind {
2416         match *self {
2417             hir::TypeBindingKind::Equality { ref ty } => {
2418                 TypeBindingKind::Equality { ty: ty.clean(cx) }
2419             }
2420             hir::TypeBindingKind::Constraint { ref bounds } => {
2421                 TypeBindingKind::Constraint { bounds: bounds.iter().map(|b| b.clean(cx)).collect() }
2422             }
2423         }
2424     }
2425 }
2426
2427 enum SimpleBound {
2428     TraitBound(Vec<PathSegment>, Vec<SimpleBound>, Vec<GenericParamDef>, hir::TraitBoundModifier),
2429     Outlives(Lifetime),
2430 }
2431
2432 impl From<GenericBound> for SimpleBound {
2433     fn from(bound: GenericBound) -> Self {
2434         match bound.clone() {
2435             GenericBound::Outlives(l) => SimpleBound::Outlives(l),
2436             GenericBound::TraitBound(t, mod_) => match t.trait_ {
2437                 Type::ResolvedPath { path, param_names, .. } => SimpleBound::TraitBound(
2438                     path.segments,
2439                     param_names.map_or_else(Vec::new, |v| {
2440                         v.iter().map(|p| SimpleBound::from(p.clone())).collect()
2441                     }),
2442                     t.generic_params,
2443                     mod_,
2444                 ),
2445                 _ => panic!("Unexpected bound {:?}", bound),
2446             },
2447         }
2448     }
2449 }