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Add checks for #[doc(keyword = "...")] and move them into rustc_passes
[rust.git] / src / librustdoc / clean / mod.rs
1 //! This module contains the "cleaned" pieces of the AST, and the functions
2 //! that clean them.
3
4 mod auto_trait;
5 mod blanket_impl;
6 crate mod cfg;
7 crate mod inline;
8 mod simplify;
9 crate mod types;
10 crate mod utils;
11
12 use rustc_ast as ast;
13 use rustc_attr as attr;
14 use rustc_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, LOCAL_CRATE};
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::ty::fold::TypeFolder;
23 use rustc_middle::ty::subst::{InternalSubsts, Subst};
24 use rustc_middle::ty::{self, AdtKind, Lift, Ty, TyCtxt};
25 use rustc_mir::const_eval::{is_const_fn, is_min_const_fn, is_unstable_const_fn};
26 use rustc_span::hygiene::{AstPass, MacroKind};
27 use rustc_span::symbol::{kw, sym, Ident, Symbol};
28 use rustc_span::{self, ExpnKind, Pos};
29 use rustc_typeck::hir_ty_to_ty;
30
31 use std::collections::hash_map::Entry;
32 use std::default::Default;
33 use std::hash::Hash;
34 use std::rc::Rc;
35 use std::{mem, vec};
36
37 use crate::core::{self, DocContext, ImplTraitParam};
38 use crate::doctree;
39
40 use utils::*;
41
42 crate use utils::{get_auto_trait_and_blanket_impls, krate, register_res};
43
44 crate use self::types::FnRetTy::*;
45 crate use self::types::ItemKind::*;
46 crate use self::types::SelfTy::*;
47 crate use self::types::Type::*;
48 crate use self::types::Visibility::{Inherited, Public};
49 crate use self::types::*;
50
51 const FN_OUTPUT_NAME: &str = "Output";
52
53 crate trait Clean<T> {
54     fn clean(&self, cx: &DocContext<'_>) -> T;
55 }
56
57 impl<T: Clean<U>, U> Clean<Vec<U>> for [T] {
58     fn clean(&self, cx: &DocContext<'_>) -> Vec<U> {
59         self.iter().map(|x| x.clean(cx)).collect()
60     }
61 }
62
63 impl<T: Clean<U>, U, V: Idx> Clean<IndexVec<V, U>> for IndexVec<V, T> {
64     fn clean(&self, cx: &DocContext<'_>) -> IndexVec<V, U> {
65         self.iter().map(|x| x.clean(cx)).collect()
66     }
67 }
68
69 impl<T: Clean<U>, U> Clean<U> for &T {
70     fn clean(&self, cx: &DocContext<'_>) -> U {
71         (**self).clean(cx)
72     }
73 }
74
75 impl<T: Clean<U>, U> Clean<U> for Rc<T> {
76     fn clean(&self, cx: &DocContext<'_>) -> U {
77         (**self).clean(cx)
78     }
79 }
80
81 impl<T: Clean<U>, U> Clean<Option<U>> for Option<T> {
82     fn clean(&self, cx: &DocContext<'_>) -> Option<U> {
83         self.as_ref().map(|v| v.clean(cx))
84     }
85 }
86
87 impl Clean<ExternalCrate> for CrateNum {
88     fn clean(&self, cx: &DocContext<'_>) -> ExternalCrate {
89         let root = DefId { krate: *self, index: CRATE_DEF_INDEX };
90         let krate_span = cx.tcx.def_span(root);
91         let krate_src = cx.sess().source_map().span_to_filename(krate_span);
92
93         // Collect all inner modules which are tagged as implementations of
94         // primitives.
95         //
96         // Note that this loop only searches the top-level items of the crate,
97         // and this is intentional. If we were to search the entire crate for an
98         // item tagged with `#[doc(primitive)]` then we would also have to
99         // search the entirety of external modules for items tagged
100         // `#[doc(primitive)]`, which is a pretty inefficient process (decoding
101         // all that metadata unconditionally).
102         //
103         // In order to keep the metadata load under control, the
104         // `#[doc(primitive)]` feature is explicitly designed to only allow the
105         // primitive tags to show up as the top level items in a crate.
106         //
107         // Also note that this does not attempt to deal with modules tagged
108         // duplicately for the same primitive. This is handled later on when
109         // rendering by delegating everything to a hash map.
110         let as_primitive = |res: Res| {
111             if let Res::Def(DefKind::Mod, def_id) = res {
112                 let attrs = cx.tcx.get_attrs(def_id).clean(cx);
113                 let mut prim = None;
114                 for attr in attrs.lists(sym::doc) {
115                     if let Some(v) = attr.value_str() {
116                         if attr.has_name(sym::primitive) {
117                             prim = PrimitiveType::from_symbol(v);
118                             if prim.is_some() {
119                                 break;
120                             }
121                             // FIXME: should warn on unknown primitives?
122                         }
123                     }
124                 }
125                 return prim.map(|p| (def_id, p));
126             }
127             None
128         };
129         let primitives = if root.is_local() {
130             cx.tcx
131                 .hir()
132                 .krate()
133                 .item
134                 .module
135                 .item_ids
136                 .iter()
137                 .filter_map(|&id| {
138                     let item = cx.tcx.hir().expect_item(id.id);
139                     match item.kind {
140                         hir::ItemKind::Mod(_) => as_primitive(Res::Def(
141                             DefKind::Mod,
142                             cx.tcx.hir().local_def_id(id.id).to_def_id(),
143                         )),
144                         hir::ItemKind::Use(ref path, hir::UseKind::Single)
145                             if item.vis.node.is_pub() =>
146                         {
147                             as_primitive(path.res).map(|(_, prim)| {
148                                 // Pretend the primitive is local.
149                                 (cx.tcx.hir().local_def_id(id.id).to_def_id(), prim)
150                             })
151                         }
152                         _ => None,
153                     }
154                 })
155                 .collect()
156         } else {
157             cx.tcx
158                 .item_children(root)
159                 .iter()
160                 .map(|item| item.res)
161                 .filter_map(as_primitive)
162                 .collect()
163         };
164
165         let as_keyword = |res: Res| {
166             if let Res::Def(DefKind::Mod, def_id) = res {
167                 let attrs = cx.tcx.get_attrs(def_id).clean(cx);
168                 let mut keyword = None;
169                 for attr in attrs.lists(sym::doc) {
170                     if attr.has_name(sym::keyword) {
171                         if let Some(v) = attr.value_str() {
172                             let k = v.to_string();
173                             if !rustc_lexer::is_ident(&k) {
174                                 let sp = get_span(&attr).unwrap_or_else(|| attr.span());
175                                 cx.tcx
176                                     .sess
177                                     .struct_span_err(
178                                         sp,
179                                         &format!("`{}` is not a valid identifier", v),
180                                     )
181                                     .emit();
182                             } else {
183                                 keyword = Some(k);
184                             }
185                             break;
186                         }
187                     }
188                 }
189                 return keyword.map(|p| (def_id, p));
190             }
191             None
192         };
193         let keywords = if root.is_local() {
194             cx.tcx
195                 .hir()
196                 .krate()
197                 .item
198                 .module
199                 .item_ids
200                 .iter()
201                 .filter_map(|&id| {
202                     let item = cx.tcx.hir().expect_item(id.id);
203                     match item.kind {
204                         hir::ItemKind::Mod(_) => as_keyword(Res::Def(
205                             DefKind::Mod,
206                             cx.tcx.hir().local_def_id(id.id).to_def_id(),
207                         )),
208                         hir::ItemKind::Use(ref path, hir::UseKind::Single)
209                             if item.vis.node.is_pub() =>
210                         {
211                             as_keyword(path.res).map(|(_, prim)| {
212                                 (cx.tcx.hir().local_def_id(id.id).to_def_id(), prim)
213                             })
214                         }
215                         _ => None,
216                     }
217                 })
218                 .collect()
219         } else {
220             cx.tcx.item_children(root).iter().map(|item| item.res).filter_map(as_keyword).collect()
221         };
222
223         ExternalCrate {
224             name: cx.tcx.crate_name(*self).to_string(),
225             src: krate_src,
226             attrs: cx.tcx.get_attrs(root).clean(cx),
227             primitives,
228             keywords,
229         }
230     }
231 }
232
233 impl Clean<Item> for doctree::Module<'_> {
234     fn clean(&self, cx: &DocContext<'_>) -> Item {
235         // maintain a stack of mod ids, for doc comment path resolution
236         // but we also need to resolve the module's own docs based on whether its docs were written
237         // inside or outside the module, so check for that
238         let attrs = self.attrs.clean(cx);
239
240         let mut items: Vec<Item> = vec![];
241         items.extend(self.imports.iter().flat_map(|x| x.clean(cx)));
242         items.extend(self.foreigns.iter().map(|x| x.clean(cx)));
243         items.extend(self.mods.iter().map(|x| x.clean(cx)));
244         items.extend(self.items.iter().map(|x| x.clean(cx)).flatten());
245         items.extend(self.macros.iter().map(|x| x.clean(cx)));
246
247         // determine if we should display the inner contents or
248         // the outer `mod` item for the source code.
249         let span = {
250             let sm = cx.sess().source_map();
251             let outer = sm.lookup_char_pos(self.where_outer.lo());
252             let inner = sm.lookup_char_pos(self.where_inner.lo());
253             if outer.file.start_pos == inner.file.start_pos {
254                 // mod foo { ... }
255                 self.where_outer
256             } else {
257                 // mod foo; (and a separate SourceFile for the contents)
258                 self.where_inner
259             }
260         };
261
262         let what_rustc_thinks = Item::from_hir_id_and_parts(
263             self.id,
264             self.name,
265             ModuleItem(Module { is_crate: self.is_crate, items }),
266             cx,
267         );
268         Item {
269             name: Some(what_rustc_thinks.name.unwrap_or_default()),
270             attrs,
271             source: span.clean(cx),
272             ..what_rustc_thinks
273         }
274     }
275 }
276
277 impl Clean<Attributes> for [ast::Attribute] {
278     fn clean(&self, cx: &DocContext<'_>) -> Attributes {
279         Attributes::from_ast(cx.sess().diagnostic(), self, None)
280     }
281 }
282
283 impl Clean<GenericBound> for hir::GenericBound<'_> {
284     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
285         match *self {
286             hir::GenericBound::Outlives(lt) => GenericBound::Outlives(lt.clean(cx)),
287             hir::GenericBound::LangItemTrait(lang_item, span, _, generic_args) => {
288                 let def_id = cx.tcx.require_lang_item(lang_item, Some(span));
289
290                 let trait_ref = ty::TraitRef::identity(cx.tcx, def_id);
291
292                 let generic_args = generic_args.clean(cx);
293                 let bindings = match generic_args {
294                     GenericArgs::AngleBracketed { bindings, .. } => bindings,
295                     _ => bug!("clean: parenthesized `GenericBound::LangItemTrait`"),
296                 };
297
298                 GenericBound::TraitBound(
299                     PolyTrait { trait_: (trait_ref, &*bindings).clean(cx), generic_params: vec![] },
300                     hir::TraitBoundModifier::None,
301                 )
302             }
303             hir::GenericBound::Trait(ref t, modifier) => {
304                 GenericBound::TraitBound(t.clean(cx), modifier)
305             }
306         }
307     }
308 }
309
310 impl Clean<Type> for (ty::TraitRef<'_>, &[TypeBinding]) {
311     fn clean(&self, cx: &DocContext<'_>) -> Type {
312         let (trait_ref, bounds) = *self;
313         inline::record_extern_fqn(cx, trait_ref.def_id, TypeKind::Trait);
314         let path = external_path(
315             cx,
316             cx.tcx.item_name(trait_ref.def_id),
317             Some(trait_ref.def_id),
318             true,
319             bounds.to_vec(),
320             trait_ref.substs,
321         );
322
323         debug!("ty::TraitRef\n  subst: {:?}\n", trait_ref.substs);
324
325         ResolvedPath { path, param_names: None, did: trait_ref.def_id, is_generic: false }
326     }
327 }
328
329 impl<'tcx> Clean<GenericBound> for ty::TraitRef<'tcx> {
330     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
331         GenericBound::TraitBound(
332             PolyTrait { trait_: (*self, &[][..]).clean(cx), generic_params: vec![] },
333             hir::TraitBoundModifier::None,
334         )
335     }
336 }
337
338 impl Clean<GenericBound> for (ty::PolyTraitRef<'_>, &[TypeBinding]) {
339     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
340         let (poly_trait_ref, bounds) = *self;
341         let poly_trait_ref = poly_trait_ref.lift_to_tcx(cx.tcx).unwrap();
342
343         // collect any late bound regions
344         let late_bound_regions: Vec<_> = cx
345             .tcx
346             .collect_referenced_late_bound_regions(&poly_trait_ref)
347             .into_iter()
348             .filter_map(|br| match br {
349                 ty::BrNamed(_, name) => Some(GenericParamDef {
350                     name: name.to_string(),
351                     kind: GenericParamDefKind::Lifetime,
352                 }),
353                 _ => None,
354             })
355             .collect();
356
357         GenericBound::TraitBound(
358             PolyTrait {
359                 trait_: (poly_trait_ref.skip_binder(), bounds).clean(cx),
360                 generic_params: late_bound_regions,
361             },
362             hir::TraitBoundModifier::None,
363         )
364     }
365 }
366
367 impl<'tcx> Clean<GenericBound> for ty::PolyTraitRef<'tcx> {
368     fn clean(&self, cx: &DocContext<'_>) -> GenericBound {
369         (*self, &[][..]).clean(cx)
370     }
371 }
372
373 impl<'tcx> Clean<Option<Vec<GenericBound>>> for InternalSubsts<'tcx> {
374     fn clean(&self, cx: &DocContext<'_>) -> Option<Vec<GenericBound>> {
375         let mut v = Vec::new();
376         v.extend(self.regions().filter_map(|r| r.clean(cx)).map(GenericBound::Outlives));
377         v.extend(self.types().map(|t| {
378             GenericBound::TraitBound(
379                 PolyTrait { trait_: t.clean(cx), generic_params: Vec::new() },
380                 hir::TraitBoundModifier::None,
381             )
382         }));
383         if !v.is_empty() { Some(v) } else { None }
384     }
385 }
386
387 impl Clean<Lifetime> for hir::Lifetime {
388     fn clean(&self, cx: &DocContext<'_>) -> Lifetime {
389         let def = cx.tcx.named_region(self.hir_id);
390         match def {
391             Some(
392                 rl::Region::EarlyBound(_, node_id, _)
393                 | rl::Region::LateBound(_, node_id, _)
394                 | rl::Region::Free(_, node_id),
395             ) => {
396                 if let Some(lt) = cx.lt_substs.borrow().get(&node_id).cloned() {
397                     return lt;
398                 }
399             }
400             _ => {}
401         }
402         Lifetime(self.name.ident().to_string())
403     }
404 }
405
406 impl Clean<Lifetime> for hir::GenericParam<'_> {
407     fn clean(&self, _: &DocContext<'_>) -> Lifetime {
408         match self.kind {
409             hir::GenericParamKind::Lifetime { .. } => {
410                 if !self.bounds.is_empty() {
411                     let mut bounds = self.bounds.iter().map(|bound| match bound {
412                         hir::GenericBound::Outlives(lt) => lt,
413                         _ => panic!(),
414                     });
415                     let name = bounds.next().expect("no more bounds").name.ident();
416                     let mut s = format!("{}: {}", self.name.ident(), name);
417                     for bound in bounds {
418                         s.push_str(&format!(" + {}", bound.name.ident()));
419                     }
420                     Lifetime(s)
421                 } else {
422                     Lifetime(self.name.ident().to_string())
423                 }
424             }
425             _ => panic!(),
426         }
427     }
428 }
429
430 impl Clean<Constant> for hir::ConstArg {
431     fn clean(&self, cx: &DocContext<'_>) -> Constant {
432         Constant {
433             type_: cx
434                 .tcx
435                 .type_of(cx.tcx.hir().body_owner_def_id(self.value.body).to_def_id())
436                 .clean(cx),
437             expr: print_const_expr(cx, self.value.body),
438             value: None,
439             is_literal: is_literal_expr(cx, self.value.body.hir_id),
440         }
441     }
442 }
443
444 impl Clean<Lifetime> for ty::GenericParamDef {
445     fn clean(&self, _cx: &DocContext<'_>) -> Lifetime {
446         Lifetime(self.name.to_string())
447     }
448 }
449
450 impl Clean<Option<Lifetime>> for ty::RegionKind {
451     fn clean(&self, cx: &DocContext<'_>) -> Option<Lifetime> {
452         match *self {
453             ty::ReStatic => Some(Lifetime::statik()),
454             ty::ReLateBound(_, ty::BrNamed(_, name)) => Some(Lifetime(name.to_string())),
455             ty::ReEarlyBound(ref data) => Some(Lifetime(data.name.clean(cx))),
456
457             ty::ReLateBound(..)
458             | ty::ReFree(..)
459             | ty::ReVar(..)
460             | ty::RePlaceholder(..)
461             | ty::ReEmpty(_)
462             | ty::ReErased => {
463                 debug!("cannot clean region {:?}", self);
464                 None
465             }
466         }
467     }
468 }
469
470 impl Clean<WherePredicate> for hir::WherePredicate<'_> {
471     fn clean(&self, cx: &DocContext<'_>) -> WherePredicate {
472         match *self {
473             hir::WherePredicate::BoundPredicate(ref wbp) => WherePredicate::BoundPredicate {
474                 ty: wbp.bounded_ty.clean(cx),
475                 bounds: wbp.bounds.clean(cx),
476             },
477
478             hir::WherePredicate::RegionPredicate(ref wrp) => WherePredicate::RegionPredicate {
479                 lifetime: wrp.lifetime.clean(cx),
480                 bounds: wrp.bounds.clean(cx),
481             },
482
483             hir::WherePredicate::EqPredicate(ref wrp) => {
484                 WherePredicate::EqPredicate { lhs: wrp.lhs_ty.clean(cx), rhs: wrp.rhs_ty.clean(cx) }
485             }
486         }
487     }
488 }
489
490 impl<'a> Clean<Option<WherePredicate>> for ty::Predicate<'a> {
491     fn clean(&self, cx: &DocContext<'_>) -> Option<WherePredicate> {
492         match self.skip_binders() {
493             ty::PredicateAtom::Trait(pred, _) => Some(ty::Binder::bind(pred).clean(cx)),
494             ty::PredicateAtom::RegionOutlives(pred) => pred.clean(cx),
495             ty::PredicateAtom::TypeOutlives(pred) => pred.clean(cx),
496             ty::PredicateAtom::Projection(pred) => Some(pred.clean(cx)),
497
498             ty::PredicateAtom::Subtype(..)
499             | ty::PredicateAtom::WellFormed(..)
500             | ty::PredicateAtom::ObjectSafe(..)
501             | ty::PredicateAtom::ClosureKind(..)
502             | ty::PredicateAtom::ConstEvaluatable(..)
503             | ty::PredicateAtom::ConstEquate(..)
504             | ty::PredicateAtom::TypeWellFormedFromEnv(..) => panic!("not user writable"),
505         }
506     }
507 }
508
509 impl<'a> Clean<WherePredicate> for ty::PolyTraitPredicate<'a> {
510     fn clean(&self, cx: &DocContext<'_>) -> WherePredicate {
511         let poly_trait_ref = self.map_bound(|pred| pred.trait_ref);
512         WherePredicate::BoundPredicate {
513             ty: poly_trait_ref.skip_binder().self_ty().clean(cx),
514             bounds: vec![poly_trait_ref.clean(cx)],
515         }
516     }
517 }
518
519 impl<'tcx> Clean<Option<WherePredicate>>
520     for ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
521 {
522     fn clean(&self, cx: &DocContext<'_>) -> Option<WherePredicate> {
523         let ty::OutlivesPredicate(a, b) = self;
524
525         if let (ty::ReEmpty(_), ty::ReEmpty(_)) = (a, b) {
526             return None;
527         }
528
529         Some(WherePredicate::RegionPredicate {
530             lifetime: a.clean(cx).expect("failed to clean lifetime"),
531             bounds: vec![GenericBound::Outlives(b.clean(cx).expect("failed to clean bounds"))],
532         })
533     }
534 }
535
536 impl<'tcx> Clean<Option<WherePredicate>> for ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>> {
537     fn clean(&self, cx: &DocContext<'_>) -> Option<WherePredicate> {
538         let ty::OutlivesPredicate(ty, lt) = self;
539
540         if let ty::ReEmpty(_) = lt {
541             return None;
542         }
543
544         Some(WherePredicate::BoundPredicate {
545             ty: ty.clean(cx),
546             bounds: vec![GenericBound::Outlives(lt.clean(cx).expect("failed to clean lifetimes"))],
547         })
548     }
549 }
550
551 impl<'tcx> Clean<WherePredicate> for ty::ProjectionPredicate<'tcx> {
552     fn clean(&self, cx: &DocContext<'_>) -> WherePredicate {
553         let ty::ProjectionPredicate { projection_ty, ty } = self;
554         WherePredicate::EqPredicate { lhs: projection_ty.clean(cx), rhs: ty.clean(cx) }
555     }
556 }
557
558 impl<'tcx> Clean<Type> for ty::ProjectionTy<'tcx> {
559     fn clean(&self, cx: &DocContext<'_>) -> Type {
560         let lifted = self.lift_to_tcx(cx.tcx).unwrap();
561         let trait_ = match lifted.trait_ref(cx.tcx).clean(cx) {
562             GenericBound::TraitBound(t, _) => t.trait_,
563             GenericBound::Outlives(_) => panic!("cleaning a trait got a lifetime"),
564         };
565         Type::QPath {
566             name: cx.tcx.associated_item(self.item_def_id).ident.name.clean(cx),
567             self_type: box self.self_ty().clean(cx),
568             trait_: box trait_,
569         }
570     }
571 }
572
573 impl Clean<GenericParamDef> for ty::GenericParamDef {
574     fn clean(&self, cx: &DocContext<'_>) -> GenericParamDef {
575         let (name, kind) = match self.kind {
576             ty::GenericParamDefKind::Lifetime => {
577                 (self.name.to_string(), GenericParamDefKind::Lifetime)
578             }
579             ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
580                 let default =
581                     if has_default { Some(cx.tcx.type_of(self.def_id).clean(cx)) } else { None };
582                 (
583                     self.name.clean(cx),
584                     GenericParamDefKind::Type {
585                         did: self.def_id,
586                         bounds: vec![], // These are filled in from the where-clauses.
587                         default,
588                         synthetic,
589                     },
590                 )
591             }
592             ty::GenericParamDefKind::Const { .. } => (
593                 self.name.clean(cx),
594                 GenericParamDefKind::Const {
595                     did: self.def_id,
596                     ty: cx.tcx.type_of(self.def_id).clean(cx),
597                 },
598             ),
599         };
600
601         GenericParamDef { name, kind }
602     }
603 }
604
605 impl Clean<GenericParamDef> for hir::GenericParam<'_> {
606     fn clean(&self, cx: &DocContext<'_>) -> GenericParamDef {
607         let (name, kind) = match self.kind {
608             hir::GenericParamKind::Lifetime { .. } => {
609                 let name = if !self.bounds.is_empty() {
610                     let mut bounds = self.bounds.iter().map(|bound| match bound {
611                         hir::GenericBound::Outlives(lt) => lt,
612                         _ => panic!(),
613                     });
614                     let name = bounds.next().expect("no more bounds").name.ident();
615                     let mut s = format!("{}: {}", self.name.ident(), name);
616                     for bound in bounds {
617                         s.push_str(&format!(" + {}", bound.name.ident()));
618                     }
619                     s
620                 } else {
621                     self.name.ident().to_string()
622                 };
623                 (name, GenericParamDefKind::Lifetime)
624             }
625             hir::GenericParamKind::Type { ref default, synthetic } => (
626                 self.name.ident().name.clean(cx),
627                 GenericParamDefKind::Type {
628                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
629                     bounds: self.bounds.clean(cx),
630                     default: default.clean(cx),
631                     synthetic,
632                 },
633             ),
634             hir::GenericParamKind::Const { ref ty } => (
635                 self.name.ident().name.clean(cx),
636                 GenericParamDefKind::Const {
637                     did: cx.tcx.hir().local_def_id(self.hir_id).to_def_id(),
638                     ty: ty.clean(cx),
639                 },
640             ),
641         };
642
643         GenericParamDef { name, kind }
644     }
645 }
646
647 impl Clean<Generics> for hir::Generics<'_> {
648     fn clean(&self, cx: &DocContext<'_>) -> Generics {
649         // Synthetic type-parameters are inserted after normal ones.
650         // In order for normal parameters to be able to refer to synthetic ones,
651         // scans them first.
652         fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
653             match param.kind {
654                 hir::GenericParamKind::Type { synthetic, .. } => {
655                     synthetic == Some(hir::SyntheticTyParamKind::ImplTrait)
656                 }
657                 _ => false,
658             }
659         }
660         let impl_trait_params = self
661             .params
662             .iter()
663             .filter(|param| is_impl_trait(param))
664             .map(|param| {
665                 let param: GenericParamDef = param.clean(cx);
666                 match param.kind {
667                     GenericParamDefKind::Lifetime => unreachable!(),
668                     GenericParamDefKind::Type { did, ref bounds, .. } => {
669                         cx.impl_trait_bounds.borrow_mut().insert(did.into(), bounds.clone());
670                     }
671                     GenericParamDefKind::Const { .. } => unreachable!(),
672                 }
673                 param
674             })
675             .collect::<Vec<_>>();
676
677         let mut params = Vec::with_capacity(self.params.len());
678         for p in self.params.iter().filter(|p| !is_impl_trait(p)) {
679             let p = p.clean(cx);
680             params.push(p);
681         }
682         params.extend(impl_trait_params);
683
684         let mut generics =
685             Generics { params, where_predicates: self.where_clause.predicates.clean(cx) };
686
687         // Some duplicates are generated for ?Sized bounds between type params and where
688         // predicates. The point in here is to move the bounds definitions from type params
689         // to where predicates when such cases occur.
690         for where_pred in &mut generics.where_predicates {
691             match *where_pred {
692                 WherePredicate::BoundPredicate { ty: Generic(ref name), ref mut bounds } => {
693                     if bounds.is_empty() {
694                         for param in &mut generics.params {
695                             match param.kind {
696                                 GenericParamDefKind::Lifetime => {}
697                                 GenericParamDefKind::Type { bounds: ref mut ty_bounds, .. } => {
698                                     if &param.name == name {
699                                         mem::swap(bounds, ty_bounds);
700                                         break;
701                                     }
702                                 }
703                                 GenericParamDefKind::Const { .. } => {}
704                             }
705                         }
706                     }
707                 }
708                 _ => continue,
709             }
710         }
711         generics
712     }
713 }
714
715 impl<'a, 'tcx> Clean<Generics> for (&'a ty::Generics, ty::GenericPredicates<'tcx>) {
716     fn clean(&self, cx: &DocContext<'_>) -> Generics {
717         use self::WherePredicate as WP;
718         use std::collections::BTreeMap;
719
720         let (gens, preds) = *self;
721
722         // Don't populate `cx.impl_trait_bounds` before `clean`ning `where` clauses,
723         // since `Clean for ty::Predicate` would consume them.
724         let mut impl_trait = BTreeMap::<ImplTraitParam, Vec<GenericBound>>::default();
725
726         // Bounds in the type_params and lifetimes fields are repeated in the
727         // predicates field (see rustc_typeck::collect::ty_generics), so remove
728         // them.
729         let stripped_params = gens
730             .params
731             .iter()
732             .filter_map(|param| match param.kind {
733                 ty::GenericParamDefKind::Lifetime => Some(param.clean(cx)),
734                 ty::GenericParamDefKind::Type { synthetic, .. } => {
735                     if param.name == kw::SelfUpper {
736                         assert_eq!(param.index, 0);
737                         return None;
738                     }
739                     if synthetic == Some(hir::SyntheticTyParamKind::ImplTrait) {
740                         impl_trait.insert(param.index.into(), vec![]);
741                         return None;
742                     }
743                     Some(param.clean(cx))
744                 }
745                 ty::GenericParamDefKind::Const { .. } => Some(param.clean(cx)),
746             })
747             .collect::<Vec<GenericParamDef>>();
748
749         // param index -> [(DefId of trait, associated type name, type)]
750         let mut impl_trait_proj = FxHashMap::<u32, Vec<(DefId, String, Ty<'tcx>)>>::default();
751
752         let where_predicates = preds
753             .predicates
754             .iter()
755             .flat_map(|(p, _)| {
756                 let mut projection = None;
757                 let param_idx = (|| {
758                     match p.skip_binders() {
759                         ty::PredicateAtom::Trait(pred, _constness) => {
760                             if let ty::Param(param) = pred.self_ty().kind() {
761                                 return Some(param.index);
762                             }
763                         }
764                         ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(ty, _reg)) => {
765                             if let ty::Param(param) = ty.kind() {
766                                 return Some(param.index);
767                             }
768                         }
769                         ty::PredicateAtom::Projection(p) => {
770                             if let ty::Param(param) = p.projection_ty.self_ty().kind() {
771                                 projection = Some(ty::Binder::bind(p));
772                                 return Some(param.index);
773                             }
774                         }
775                         _ => (),
776                     }
777
778                     None
779                 })();
780
781                 if let Some(param_idx) = param_idx {
782                     if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
783                         let p = p.clean(cx)?;
784
785                         b.extend(
786                             p.get_bounds()
787                                 .into_iter()
788                                 .flatten()
789                                 .cloned()
790                                 .filter(|b| !b.is_sized_bound(cx)),
791                         );
792
793                         let proj = projection
794                             .map(|p| (p.skip_binder().projection_ty.clean(cx), p.skip_binder().ty));
795                         if let Some(((_, trait_did, name), rhs)) =
796                             proj.as_ref().and_then(|(lhs, rhs)| Some((lhs.projection()?, rhs)))
797                         {
798                             impl_trait_proj.entry(param_idx).or_default().push((
799                                 trait_did,
800                                 name.to_string(),
801                                 rhs,
802                             ));
803                         }
804
805                         return None;
806                     }
807                 }
808
809                 Some(p)
810             })
811             .collect::<Vec<_>>();
812
813         for (param, mut bounds) in impl_trait {
814             // Move trait bounds to the front.
815             bounds.sort_by_key(|b| if let GenericBound::TraitBound(..) = b { false } else { true });
816
817             if let crate::core::ImplTraitParam::ParamIndex(idx) = param {
818                 if let Some(proj) = impl_trait_proj.remove(&idx) {
819                     for (trait_did, name, rhs) in proj {
820                         simplify::merge_bounds(cx, &mut bounds, trait_did, &name, &rhs.clean(cx));
821                     }
822                 }
823             } else {
824                 unreachable!();
825             }
826
827             cx.impl_trait_bounds.borrow_mut().insert(param, bounds);
828         }
829
830         // Now that `cx.impl_trait_bounds` is populated, we can process
831         // remaining predicates which could contain `impl Trait`.
832         let mut where_predicates =
833             where_predicates.into_iter().flat_map(|p| p.clean(cx)).collect::<Vec<_>>();
834
835         // Type parameters have a Sized bound by default unless removed with
836         // ?Sized. Scan through the predicates and mark any type parameter with
837         // a Sized bound, removing the bounds as we find them.
838         //
839         // Note that associated types also have a sized bound by default, but we
840         // don't actually know the set of associated types right here so that's
841         // handled in cleaning associated types
842         let mut sized_params = FxHashSet::default();
843         where_predicates.retain(|pred| match *pred {
844             WP::BoundPredicate { ty: Generic(ref g), ref bounds } => {
845                 if bounds.iter().any(|b| b.is_sized_bound(cx)) {
846                     sized_params.insert(g.clone());
847                     false
848                 } else {
849                     true
850                 }
851             }
852             _ => true,
853         });
854
855         // Run through the type parameters again and insert a ?Sized
856         // unbound for any we didn't find to be Sized.
857         for tp in &stripped_params {
858             if matches!(tp.kind, types::GenericParamDefKind::Type { .. })
859                 && !sized_params.contains(&tp.name)
860             {
861                 where_predicates.push(WP::BoundPredicate {
862                     ty: Type::Generic(tp.name.clone()),
863                     bounds: vec![GenericBound::maybe_sized(cx)],
864                 })
865             }
866         }
867
868         // It would be nice to collect all of the bounds on a type and recombine
869         // them if possible, to avoid e.g., `where T: Foo, T: Bar, T: Sized, T: 'a`
870         // and instead see `where T: Foo + Bar + Sized + 'a`
871
872         Generics {
873             params: stripped_params,
874             where_predicates: simplify::where_clauses(cx, where_predicates),
875         }
876     }
877 }
878
879 fn clean_fn_or_proc_macro(
880     item: &hir::Item<'_>,
881     sig: &'a hir::FnSig<'a>,
882     generics: &'a hir::Generics<'a>,
883     body_id: hir::BodyId,
884     name: &mut Symbol,
885     cx: &DocContext<'_>,
886 ) -> ItemKind {
887     let macro_kind = item.attrs.iter().find_map(|a| {
888         if a.has_name(sym::proc_macro) {
889             Some(MacroKind::Bang)
890         } else if a.has_name(sym::proc_macro_derive) {
891             Some(MacroKind::Derive)
892         } else if a.has_name(sym::proc_macro_attribute) {
893             Some(MacroKind::Attr)
894         } else {
895             None
896         }
897     });
898     match macro_kind {
899         Some(kind) => {
900             if kind == MacroKind::Derive {
901                 *name = item
902                     .attrs
903                     .lists(sym::proc_macro_derive)
904                     .find_map(|mi| mi.ident())
905                     .expect("proc-macro derives require a name")
906                     .name;
907             }
908
909             let mut helpers = Vec::new();
910             for mi in item.attrs.lists(sym::proc_macro_derive) {
911                 if !mi.has_name(sym::attributes) {
912                     continue;
913                 }
914
915                 if let Some(list) = mi.meta_item_list() {
916                     for inner_mi in list {
917                         if let Some(ident) = inner_mi.ident() {
918                             helpers.push(ident.name);
919                         }
920                     }
921                 }
922             }
923             ProcMacroItem(ProcMacro { kind, helpers: helpers.clean(cx) })
924         }
925         None => {
926             let mut func = (sig, generics, body_id).clean(cx);
927             let def_id = cx.tcx.hir().local_def_id(item.hir_id).to_def_id();
928             func.header.constness =
929                 if is_const_fn(cx.tcx, def_id) && is_unstable_const_fn(cx.tcx, def_id).is_none() {
930                     hir::Constness::Const
931                 } else {
932                     hir::Constness::NotConst
933                 };
934             FunctionItem(func)
935         }
936     }
937 }
938
939 impl<'a> Clean<Function> for (&'a hir::FnSig<'a>, &'a hir::Generics<'a>, hir::BodyId) {
940     fn clean(&self, cx: &DocContext<'_>) -> Function {
941         let (generics, decl) =
942             enter_impl_trait(cx, || (self.1.clean(cx), (&*self.0.decl, self.2).clean(cx)));
943         let (all_types, ret_types) = get_all_types(&generics, &decl, cx);
944         Function { decl, generics, header: self.0.header, all_types, ret_types }
945     }
946 }
947
948 impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], &'a [Ident]) {
949     fn clean(&self, cx: &DocContext<'_>) -> Arguments {
950         Arguments {
951             values: self
952                 .0
953                 .iter()
954                 .enumerate()
955                 .map(|(i, ty)| {
956                     let mut name = self.1.get(i).map(|ident| ident.to_string()).unwrap_or_default();
957                     if name.is_empty() {
958                         name = "_".to_string();
959                     }
960                     Argument { name, type_: ty.clean(cx) }
961                 })
962                 .collect(),
963         }
964     }
965 }
966
967 impl<'a> Clean<Arguments> for (&'a [hir::Ty<'a>], hir::BodyId) {
968     fn clean(&self, cx: &DocContext<'_>) -> Arguments {
969         let body = cx.tcx.hir().body(self.1);
970
971         Arguments {
972             values: self
973                 .0
974                 .iter()
975                 .enumerate()
976                 .map(|(i, ty)| Argument {
977                     name: name_from_pat(&body.params[i].pat),
978                     type_: ty.clean(cx),
979                 })
980                 .collect(),
981         }
982     }
983 }
984
985 impl<'a, A: Copy> Clean<FnDecl> for (&'a hir::FnDecl<'a>, A)
986 where
987     (&'a [hir::Ty<'a>], A): Clean<Arguments>,
988 {
989     fn clean(&self, cx: &DocContext<'_>) -> FnDecl {
990         FnDecl {
991             inputs: (&self.0.inputs[..], self.1).clean(cx),
992             output: self.0.output.clean(cx),
993             c_variadic: self.0.c_variadic,
994             attrs: Attributes::default(),
995         }
996     }
997 }
998
999 impl<'tcx> Clean<FnDecl> for (DefId, ty::PolyFnSig<'tcx>) {
1000     fn clean(&self, cx: &DocContext<'_>) -> FnDecl {
1001         let (did, sig) = *self;
1002         let mut names = if did.is_local() { &[] } else { cx.tcx.fn_arg_names(did) }.iter();
1003
1004         FnDecl {
1005             output: Return(sig.skip_binder().output().clean(cx)),
1006             attrs: Attributes::default(),
1007             c_variadic: sig.skip_binder().c_variadic,
1008             inputs: Arguments {
1009                 values: sig
1010                     .skip_binder()
1011                     .inputs()
1012                     .iter()
1013                     .map(|t| Argument {
1014                         type_: t.clean(cx),
1015                         name: names.next().map_or(String::new(), |name| name.to_string()),
1016                     })
1017                     .collect(),
1018             },
1019         }
1020     }
1021 }
1022
1023 impl Clean<FnRetTy> for hir::FnRetTy<'_> {
1024     fn clean(&self, cx: &DocContext<'_>) -> FnRetTy {
1025         match *self {
1026             Self::Return(ref typ) => Return(typ.clean(cx)),
1027             Self::DefaultReturn(..) => DefaultReturn,
1028         }
1029     }
1030 }
1031
1032 impl Clean<bool> for hir::IsAuto {
1033     fn clean(&self, _: &DocContext<'_>) -> bool {
1034         match *self {
1035             hir::IsAuto::Yes => true,
1036             hir::IsAuto::No => false,
1037         }
1038     }
1039 }
1040
1041 impl Clean<Type> for hir::TraitRef<'_> {
1042     fn clean(&self, cx: &DocContext<'_>) -> Type {
1043         resolve_type(cx, self.path.clean(cx), self.hir_ref_id)
1044     }
1045 }
1046
1047 impl Clean<PolyTrait> for hir::PolyTraitRef<'_> {
1048     fn clean(&self, cx: &DocContext<'_>) -> PolyTrait {
1049         PolyTrait {
1050             trait_: self.trait_ref.clean(cx),
1051             generic_params: self.bound_generic_params.clean(cx),
1052         }
1053     }
1054 }
1055
1056 impl Clean<TypeKind> for hir::def::DefKind {
1057     fn clean(&self, _: &DocContext<'_>) -> TypeKind {
1058         match *self {
1059             hir::def::DefKind::Mod => TypeKind::Module,
1060             hir::def::DefKind::Struct => TypeKind::Struct,
1061             hir::def::DefKind::Union => TypeKind::Union,
1062             hir::def::DefKind::Enum => TypeKind::Enum,
1063             hir::def::DefKind::Trait => TypeKind::Trait,
1064             hir::def::DefKind::TyAlias => TypeKind::Typedef,
1065             hir::def::DefKind::ForeignTy => TypeKind::Foreign,
1066             hir::def::DefKind::TraitAlias => TypeKind::TraitAlias,
1067             hir::def::DefKind::Fn => TypeKind::Function,
1068             hir::def::DefKind::Const => TypeKind::Const,
1069             hir::def::DefKind::Static => TypeKind::Static,
1070             hir::def::DefKind::Macro(_) => TypeKind::Macro,
1071             _ => TypeKind::Foreign,
1072         }
1073     }
1074 }
1075
1076 impl Clean<Item> for hir::TraitItem<'_> {
1077     fn clean(&self, cx: &DocContext<'_>) -> Item {
1078         let local_did = cx.tcx.hir().local_def_id(self.hir_id).to_def_id();
1079         cx.with_param_env(local_did, || {
1080             let inner = match self.kind {
1081                 hir::TraitItemKind::Const(ref ty, default) => {
1082                     AssocConstItem(ty.clean(cx), default.map(|e| print_const_expr(cx, e)))
1083                 }
1084                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
1085                     let mut m = (sig, &self.generics, body).clean(cx);
1086                     if m.header.constness == hir::Constness::Const
1087                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
1088                     {
1089                         m.header.constness = hir::Constness::NotConst;
1090                     }
1091                     MethodItem(m, None)
1092                 }
1093                 hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(ref names)) => {
1094                     let (generics, decl) = enter_impl_trait(cx, || {
1095                         (self.generics.clean(cx), (&*sig.decl, &names[..]).clean(cx))
1096                     });
1097                     let (all_types, ret_types) = get_all_types(&generics, &decl, cx);
1098                     let mut t =
1099                         Function { header: sig.header, decl, generics, all_types, ret_types };
1100                     if t.header.constness == hir::Constness::Const
1101                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
1102                     {
1103                         t.header.constness = hir::Constness::NotConst;
1104                     }
1105                     TyMethodItem(t)
1106                 }
1107                 hir::TraitItemKind::Type(ref bounds, ref default) => {
1108                     AssocTypeItem(bounds.clean(cx), default.clean(cx))
1109                 }
1110             };
1111             Item::from_def_id_and_parts(local_did, Some(self.ident.name.clean(cx)), inner, cx)
1112         })
1113     }
1114 }
1115
1116 impl Clean<Item> for hir::ImplItem<'_> {
1117     fn clean(&self, cx: &DocContext<'_>) -> Item {
1118         let local_did = cx.tcx.hir().local_def_id(self.hir_id).to_def_id();
1119         cx.with_param_env(local_did, || {
1120             let inner = match self.kind {
1121                 hir::ImplItemKind::Const(ref ty, expr) => {
1122                     AssocConstItem(ty.clean(cx), Some(print_const_expr(cx, expr)))
1123                 }
1124                 hir::ImplItemKind::Fn(ref sig, body) => {
1125                     let mut m = (sig, &self.generics, body).clean(cx);
1126                     if m.header.constness == hir::Constness::Const
1127                         && is_unstable_const_fn(cx.tcx, local_did).is_some()
1128                     {
1129                         m.header.constness = hir::Constness::NotConst;
1130                     }
1131                     MethodItem(m, Some(self.defaultness))
1132                 }
1133                 hir::ImplItemKind::TyAlias(ref ty) => {
1134                     let type_ = ty.clean(cx);
1135                     let item_type = type_.def_id().and_then(|did| inline::build_ty(cx, did));
1136                     TypedefItem(Typedef { type_, generics: Generics::default(), item_type }, true)
1137                 }
1138             };
1139             Item::from_def_id_and_parts(local_did, Some(self.ident.name.clean(cx)), inner, cx)
1140         })
1141     }
1142 }
1143
1144 impl Clean<Item> for ty::AssocItem {
1145     fn clean(&self, cx: &DocContext<'_>) -> Item {
1146         let kind = match self.kind {
1147             ty::AssocKind::Const => {
1148                 let ty = cx.tcx.type_of(self.def_id);
1149                 let default = if self.defaultness.has_value() {
1150                     Some(inline::print_inlined_const(cx, self.def_id))
1151                 } else {
1152                     None
1153                 };
1154                 AssocConstItem(ty.clean(cx), default)
1155             }
1156             ty::AssocKind::Fn => {
1157                 let generics =
1158                     (cx.tcx.generics_of(self.def_id), cx.tcx.explicit_predicates_of(self.def_id))
1159                         .clean(cx);
1160                 let sig = cx.tcx.fn_sig(self.def_id);
1161                 let mut decl = (self.def_id, sig).clean(cx);
1162
1163                 if self.fn_has_self_parameter {
1164                     let self_ty = match self.container {
1165                         ty::ImplContainer(def_id) => cx.tcx.type_of(def_id),
1166                         ty::TraitContainer(_) => cx.tcx.types.self_param,
1167                     };
1168                     let self_arg_ty = sig.input(0).skip_binder();
1169                     if self_arg_ty == self_ty {
1170                         decl.inputs.values[0].type_ = Generic(String::from("Self"));
1171                     } else if let ty::Ref(_, ty, _) = *self_arg_ty.kind() {
1172                         if ty == self_ty {
1173                             match decl.inputs.values[0].type_ {
1174                                 BorrowedRef { ref mut type_, .. } => {
1175                                     **type_ = Generic(String::from("Self"))
1176                                 }
1177                                 _ => unreachable!(),
1178                             }
1179                         }
1180                     }
1181                 }
1182
1183                 let provided = match self.container {
1184                     ty::ImplContainer(_) => true,
1185                     ty::TraitContainer(_) => self.defaultness.has_value(),
1186                 };
1187                 let (all_types, ret_types) = get_all_types(&generics, &decl, cx);
1188                 if provided {
1189                     let constness = if is_min_const_fn(cx.tcx, self.def_id) {
1190                         hir::Constness::Const
1191                     } else {
1192                         hir::Constness::NotConst
1193                     };
1194                     let asyncness = cx.tcx.asyncness(self.def_id);
1195                     let defaultness = match self.container {
1196                         ty::ImplContainer(_) => Some(self.defaultness),
1197                         ty::TraitContainer(_) => None,
1198                     };
1199                     MethodItem(
1200                         Function {
1201                             generics,
1202                             decl,
1203                             header: hir::FnHeader {
1204                                 unsafety: sig.unsafety(),
1205                                 abi: sig.abi(),
1206                                 constness,
1207                                 asyncness,
1208                             },
1209                             all_types,
1210                             ret_types,
1211                         },
1212                         defaultness,
1213                     )
1214                 } else {
1215                     TyMethodItem(Function {
1216                         generics,
1217                         decl,
1218                         header: hir::FnHeader {
1219                             unsafety: sig.unsafety(),
1220                             abi: sig.abi(),
1221                             constness: hir::Constness::NotConst,
1222                             asyncness: hir::IsAsync::NotAsync,
1223                         },
1224                         all_types,
1225                         ret_types,
1226                     })
1227                 }
1228             }
1229             ty::AssocKind::Type => {
1230                 let my_name = self.ident.name.clean(cx);
1231
1232                 if let ty::TraitContainer(_) = self.container {
1233                     let bounds = cx.tcx.explicit_item_bounds(self.def_id);
1234                     let predicates = ty::GenericPredicates { parent: None, predicates: bounds };
1235                     let generics = (cx.tcx.generics_of(self.def_id), predicates).clean(cx);
1236                     let mut bounds = generics
1237                         .where_predicates
1238                         .iter()
1239                         .filter_map(|pred| {
1240                             let (name, self_type, trait_, bounds) = match *pred {
1241                                 WherePredicate::BoundPredicate {
1242                                     ty: QPath { ref name, ref self_type, ref trait_ },
1243                                     ref bounds,
1244                                 } => (name, self_type, trait_, bounds),
1245                                 _ => return None,
1246                             };
1247                             if *name != my_name {
1248                                 return None;
1249                             }
1250                             match **trait_ {
1251                                 ResolvedPath { did, .. } if did == self.container.id() => {}
1252                                 _ => return None,
1253                             }
1254                             match **self_type {
1255                                 Generic(ref s) if *s == "Self" => {}
1256                                 _ => return None,
1257                             }
1258                             Some(bounds)
1259                         })
1260                         .flat_map(|i| i.iter().cloned())
1261                         .collect::<Vec<_>>();
1262                     // Our Sized/?Sized bound didn't get handled when creating the generics
1263                     // because we didn't actually get our whole set of bounds until just now
1264                     // (some of them may have come from the trait). If we do have a sized
1265                     // bound, we remove it, and if we don't then we add the `?Sized` bound
1266                     // at the end.
1267                     match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1268                         Some(i) => {
1269                             bounds.remove(i);
1270                         }
1271                         None => bounds.push(GenericBound::maybe_sized(cx)),
1272                     }
1273
1274                     let ty = if self.defaultness.has_value() {
1275                         Some(cx.tcx.type_of(self.def_id))
1276                     } else {
1277                         None
1278                     };
1279
1280                     AssocTypeItem(bounds, ty.clean(cx))
1281                 } else {
1282                     let type_ = cx.tcx.type_of(self.def_id).clean(cx);
1283                     let item_type = type_.def_id().and_then(|did| inline::build_ty(cx, did));
1284                     TypedefItem(
1285                         Typedef {
1286                             type_,
1287                             generics: Generics { params: Vec::new(), where_predicates: Vec::new() },
1288                             item_type,
1289                         },
1290                         true,
1291                     )
1292                 }
1293             }
1294         };
1295
1296         Item::from_def_id_and_parts(self.def_id, Some(self.ident.name.clean(cx)), kind, cx)
1297     }
1298 }
1299
1300 fn clean_qpath(hir_ty: &hir::Ty<'_>, cx: &DocContext<'_>) -> Type {
1301     use rustc_hir::GenericParamCount;
1302     let hir::Ty { hir_id, span, ref kind } = *hir_ty;
1303     let qpath = match kind {
1304         hir::TyKind::Path(qpath) => qpath,
1305         _ => unreachable!(),
1306     };
1307
1308     match qpath {
1309         hir::QPath::Resolved(None, ref path) => {
1310             if let Res::Def(DefKind::TyParam, did) = path.res {
1311                 if let Some(new_ty) = cx.ty_substs.borrow().get(&did).cloned() {
1312                     return new_ty;
1313                 }
1314                 if let Some(bounds) = cx.impl_trait_bounds.borrow_mut().remove(&did.into()) {
1315                     return ImplTrait(bounds);
1316                 }
1317             }
1318
1319             let mut alias = None;
1320             if let Res::Def(DefKind::TyAlias, def_id) = path.res {
1321                 // Substitute private type aliases
1322                 if let Some(def_id) = def_id.as_local() {
1323                     let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id);
1324                     if !cx.renderinfo.borrow().access_levels.is_exported(def_id.to_def_id()) {
1325                         alias = Some(&cx.tcx.hir().expect_item(hir_id).kind);
1326                     }
1327                 }
1328             };
1329
1330             if let Some(&hir::ItemKind::TyAlias(ref ty, ref generics)) = alias {
1331                 let provided_params = &path.segments.last().expect("segments were empty");
1332                 let mut ty_substs = FxHashMap::default();
1333                 let mut lt_substs = FxHashMap::default();
1334                 let mut ct_substs = FxHashMap::default();
1335                 let generic_args = provided_params.generic_args();
1336                 {
1337                     let mut indices: GenericParamCount = Default::default();
1338                     for param in generics.params.iter() {
1339                         match param.kind {
1340                             hir::GenericParamKind::Lifetime { .. } => {
1341                                 let mut j = 0;
1342                                 let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1343                                     hir::GenericArg::Lifetime(lt) => {
1344                                         if indices.lifetimes == j {
1345                                             return Some(lt);
1346                                         }
1347                                         j += 1;
1348                                         None
1349                                     }
1350                                     _ => None,
1351                                 });
1352                                 if let Some(lt) = lifetime.cloned() {
1353                                     let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1354                                     let cleaned = if !lt.is_elided() {
1355                                         lt.clean(cx)
1356                                     } else {
1357                                         self::types::Lifetime::elided()
1358                                     };
1359                                     lt_substs.insert(lt_def_id.to_def_id(), cleaned);
1360                                 }
1361                                 indices.lifetimes += 1;
1362                             }
1363                             hir::GenericParamKind::Type { ref default, .. } => {
1364                                 let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1365                                 let mut j = 0;
1366                                 let type_ = generic_args.args.iter().find_map(|arg| match arg {
1367                                     hir::GenericArg::Type(ty) => {
1368                                         if indices.types == j {
1369                                             return Some(ty);
1370                                         }
1371                                         j += 1;
1372                                         None
1373                                     }
1374                                     _ => None,
1375                                 });
1376                                 if let Some(ty) = type_ {
1377                                     ty_substs.insert(ty_param_def_id.to_def_id(), ty.clean(cx));
1378                                 } else if let Some(default) = *default {
1379                                     ty_substs
1380                                         .insert(ty_param_def_id.to_def_id(), default.clean(cx));
1381                                 }
1382                                 indices.types += 1;
1383                             }
1384                             hir::GenericParamKind::Const { .. } => {
1385                                 let const_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1386                                 let mut j = 0;
1387                                 let const_ = generic_args.args.iter().find_map(|arg| match arg {
1388                                     hir::GenericArg::Const(ct) => {
1389                                         if indices.consts == j {
1390                                             return Some(ct);
1391                                         }
1392                                         j += 1;
1393                                         None
1394                                     }
1395                                     _ => None,
1396                                 });
1397                                 if let Some(ct) = const_ {
1398                                     ct_substs.insert(const_param_def_id.to_def_id(), ct.clean(cx));
1399                                 }
1400                                 // FIXME(const_generics:defaults)
1401                                 indices.consts += 1;
1402                             }
1403                         }
1404                     }
1405                 }
1406                 return cx.enter_alias(ty_substs, lt_substs, ct_substs, || ty.clean(cx));
1407             }
1408             resolve_type(cx, path.clean(cx), hir_id)
1409         }
1410         hir::QPath::Resolved(Some(ref qself), ref p) => {
1411             // Try to normalize `<X as Y>::T` to a type
1412             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1413             if let Some(normalized_value) = normalize(cx, ty) {
1414                 return normalized_value.clean(cx);
1415             }
1416
1417             let segments = if p.is_global() { &p.segments[1..] } else { &p.segments };
1418             let trait_segments = &segments[..segments.len() - 1];
1419             let trait_path = self::Path {
1420                 global: p.is_global(),
1421                 res: Res::Def(
1422                     DefKind::Trait,
1423                     cx.tcx.associated_item(p.res.def_id()).container.id(),
1424                 ),
1425                 segments: trait_segments.clean(cx),
1426             };
1427             Type::QPath {
1428                 name: p.segments.last().expect("segments were empty").ident.name.clean(cx),
1429                 self_type: box qself.clean(cx),
1430                 trait_: box resolve_type(cx, trait_path, hir_id),
1431             }
1432         }
1433         hir::QPath::TypeRelative(ref qself, ref segment) => {
1434             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1435             let res = if let ty::Projection(proj) = ty.kind() {
1436                 Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id)
1437             } else {
1438                 Res::Err
1439             };
1440             let trait_path = hir::Path { span, res, segments: &[] };
1441             Type::QPath {
1442                 name: segment.ident.name.clean(cx),
1443                 self_type: box qself.clean(cx),
1444                 trait_: box resolve_type(cx, trait_path.clean(cx), hir_id),
1445             }
1446         }
1447         hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1448     }
1449 }
1450
1451 impl Clean<Type> for hir::Ty<'_> {
1452     fn clean(&self, cx: &DocContext<'_>) -> Type {
1453         use rustc_hir::*;
1454
1455         match self.kind {
1456             TyKind::Never => Never,
1457             TyKind::Ptr(ref m) => RawPointer(m.mutbl, box m.ty.clean(cx)),
1458             TyKind::Rptr(ref l, ref m) => {
1459                 let lifetime = if l.is_elided() { None } else { Some(l.clean(cx)) };
1460                 BorrowedRef { lifetime, mutability: m.mutbl, type_: box m.ty.clean(cx) }
1461             }
1462             TyKind::Slice(ref ty) => Slice(box ty.clean(cx)),
1463             TyKind::Array(ref ty, ref length) => {
1464                 let def_id = cx.tcx.hir().local_def_id(length.hir_id);
1465                 // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1466                 // as we currently do not supply the parent generics to anonymous constants
1467                 // but do allow `ConstKind::Param`.
1468                 //
1469                 // `const_eval_poly` tries to to first substitute generic parameters which
1470                 // results in an ICE while manually constructing the constant and using `eval`
1471                 // does nothing for `ConstKind::Param`.
1472                 let ct = ty::Const::from_anon_const(cx.tcx, def_id);
1473                 let param_env = cx.tcx.param_env(def_id);
1474                 let length = print_const(cx, ct.eval(cx.tcx, param_env));
1475                 Array(box ty.clean(cx), length)
1476             }
1477             TyKind::Tup(ref tys) => Tuple(tys.clean(cx)),
1478             TyKind::OpaqueDef(item_id, _) => {
1479                 let item = cx.tcx.hir().expect_item(item_id.id);
1480                 if let hir::ItemKind::OpaqueTy(ref ty) = item.kind {
1481                     ImplTrait(ty.bounds.clean(cx))
1482                 } else {
1483                     unreachable!()
1484                 }
1485             }
1486             TyKind::Path(_) => clean_qpath(&self, cx),
1487             TyKind::TraitObject(ref bounds, ref lifetime) => {
1488                 match bounds[0].clean(cx).trait_ {
1489                     ResolvedPath { path, param_names: None, did, is_generic } => {
1490                         let mut bounds: Vec<self::GenericBound> = bounds[1..]
1491                             .iter()
1492                             .map(|bound| {
1493                                 self::GenericBound::TraitBound(
1494                                     bound.clean(cx),
1495                                     hir::TraitBoundModifier::None,
1496                                 )
1497                             })
1498                             .collect();
1499                         if !lifetime.is_elided() {
1500                             bounds.push(self::GenericBound::Outlives(lifetime.clean(cx)));
1501                         }
1502                         ResolvedPath { path, param_names: Some(bounds), did, is_generic }
1503                     }
1504                     _ => Infer, // shouldn't happen
1505                 }
1506             }
1507             TyKind::BareFn(ref barefn) => BareFunction(box barefn.clean(cx)),
1508             TyKind::Infer | TyKind::Err => Infer,
1509             TyKind::Typeof(..) => panic!("unimplemented type {:?}", self.kind),
1510         }
1511     }
1512 }
1513
1514 /// Returns `None` if the type could not be normalized
1515 fn normalize(cx: &DocContext<'tcx>, ty: Ty<'_>) -> Option<Ty<'tcx>> {
1516     // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1517     if !cx.tcx.sess.opts.debugging_opts.normalize_docs {
1518         return None;
1519     }
1520
1521     use crate::rustc_trait_selection::infer::TyCtxtInferExt;
1522     use crate::rustc_trait_selection::traits::query::normalize::AtExt;
1523     use rustc_middle::traits::ObligationCause;
1524
1525     // Try to normalize `<X as Y>::T` to a type
1526     let lifted = ty.lift_to_tcx(cx.tcx).unwrap();
1527     let normalized = cx.tcx.infer_ctxt().enter(|infcx| {
1528         infcx
1529             .at(&ObligationCause::dummy(), cx.param_env.get())
1530             .normalize(lifted)
1531             .map(|resolved| infcx.resolve_vars_if_possible(resolved.value))
1532     });
1533     match normalized {
1534         Ok(normalized_value) => {
1535             debug!("normalized {:?} to {:?}", ty, normalized_value);
1536             Some(normalized_value)
1537         }
1538         Err(err) => {
1539             debug!("failed to normalize {:?}: {:?}", ty, err);
1540             None
1541         }
1542     }
1543 }
1544
1545 impl<'tcx> Clean<Type> for Ty<'tcx> {
1546     fn clean(&self, cx: &DocContext<'_>) -> Type {
1547         debug!("cleaning type: {:?}", self);
1548         let ty = normalize(cx, self).unwrap_or(self);
1549         match *ty.kind() {
1550             ty::Never => Never,
1551             ty::Bool => Primitive(PrimitiveType::Bool),
1552             ty::Char => Primitive(PrimitiveType::Char),
1553             ty::Int(int_ty) => Primitive(int_ty.into()),
1554             ty::Uint(uint_ty) => Primitive(uint_ty.into()),
1555             ty::Float(float_ty) => Primitive(float_ty.into()),
1556             ty::Str => Primitive(PrimitiveType::Str),
1557             ty::Slice(ty) => Slice(box ty.clean(cx)),
1558             ty::Array(ty, n) => {
1559                 let mut n = cx.tcx.lift(n).expect("array lift failed");
1560                 n = n.eval(cx.tcx, ty::ParamEnv::reveal_all());
1561                 let n = print_const(cx, n);
1562                 Array(box ty.clean(cx), n)
1563             }
1564             ty::RawPtr(mt) => RawPointer(mt.mutbl, box mt.ty.clean(cx)),
1565             ty::Ref(r, ty, mutbl) => {
1566                 BorrowedRef { lifetime: r.clean(cx), mutability: mutbl, type_: box ty.clean(cx) }
1567             }
1568             ty::FnDef(..) | ty::FnPtr(_) => {
1569                 let ty = cx.tcx.lift(*self).expect("FnPtr lift failed");
1570                 let sig = ty.fn_sig(cx.tcx);
1571                 let def_id = DefId::local(CRATE_DEF_INDEX);
1572                 BareFunction(box BareFunctionDecl {
1573                     unsafety: sig.unsafety(),
1574                     generic_params: Vec::new(),
1575                     decl: (def_id, sig).clean(cx),
1576                     abi: sig.abi(),
1577                 })
1578             }
1579             ty::Adt(def, substs) => {
1580                 let did = def.did;
1581                 let kind = match def.adt_kind() {
1582                     AdtKind::Struct => TypeKind::Struct,
1583                     AdtKind::Union => TypeKind::Union,
1584                     AdtKind::Enum => TypeKind::Enum,
1585                 };
1586                 inline::record_extern_fqn(cx, did, kind);
1587                 let path = external_path(cx, cx.tcx.item_name(did), None, false, vec![], substs);
1588                 ResolvedPath { path, param_names: None, did, is_generic: false }
1589             }
1590             ty::Foreign(did) => {
1591                 inline::record_extern_fqn(cx, did, TypeKind::Foreign);
1592                 let path = external_path(
1593                     cx,
1594                     cx.tcx.item_name(did),
1595                     None,
1596                     false,
1597                     vec![],
1598                     InternalSubsts::empty(),
1599                 );
1600                 ResolvedPath { path, param_names: None, did, is_generic: false }
1601             }
1602             ty::Dynamic(ref obj, ref reg) => {
1603                 // HACK: pick the first `did` as the `did` of the trait object. Someone
1604                 // might want to implement "native" support for marker-trait-only
1605                 // trait objects.
1606                 let mut dids = obj.principal_def_id().into_iter().chain(obj.auto_traits());
1607                 let did = dids
1608                     .next()
1609                     .unwrap_or_else(|| panic!("found trait object `{:?}` with no traits?", self));
1610                 let substs = match obj.principal() {
1611                     Some(principal) => principal.skip_binder().substs,
1612                     // marker traits have no substs.
1613                     _ => cx.tcx.intern_substs(&[]),
1614                 };
1615
1616                 inline::record_extern_fqn(cx, did, TypeKind::Trait);
1617
1618                 let mut param_names = vec![];
1619                 if let Some(b) = reg.clean(cx) {
1620                     param_names.push(GenericBound::Outlives(b));
1621                 }
1622                 for did in dids {
1623                     let empty = cx.tcx.intern_substs(&[]);
1624                     let path =
1625                         external_path(cx, cx.tcx.item_name(did), Some(did), false, vec![], empty);
1626                     inline::record_extern_fqn(cx, did, TypeKind::Trait);
1627                     let bound = GenericBound::TraitBound(
1628                         PolyTrait {
1629                             trait_: ResolvedPath {
1630                                 path,
1631                                 param_names: None,
1632                                 did,
1633                                 is_generic: false,
1634                             },
1635                             generic_params: Vec::new(),
1636                         },
1637                         hir::TraitBoundModifier::None,
1638                     );
1639                     param_names.push(bound);
1640                 }
1641
1642                 let mut bindings = vec![];
1643                 for pb in obj.projection_bounds() {
1644                     bindings.push(TypeBinding {
1645                         name: cx.tcx.associated_item(pb.item_def_id()).ident.name.clean(cx),
1646                         kind: TypeBindingKind::Equality { ty: pb.skip_binder().ty.clean(cx) },
1647                     });
1648                 }
1649
1650                 let path =
1651                     external_path(cx, cx.tcx.item_name(did), Some(did), false, bindings, substs);
1652                 ResolvedPath { path, param_names: Some(param_names), did, is_generic: false }
1653             }
1654             ty::Tuple(ref t) => {
1655                 Tuple(t.iter().map(|t| t.expect_ty()).collect::<Vec<_>>().clean(cx))
1656             }
1657
1658             ty::Projection(ref data) => data.clean(cx),
1659
1660             ty::Param(ref p) => {
1661                 if let Some(bounds) = cx.impl_trait_bounds.borrow_mut().remove(&p.index.into()) {
1662                     ImplTrait(bounds)
1663                 } else {
1664                     Generic(p.name.to_string())
1665                 }
1666             }
1667
1668             ty::Opaque(def_id, substs) => {
1669                 // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1670                 // by looking up the bounds associated with the def_id.
1671                 let substs = cx.tcx.lift(substs).expect("Opaque lift failed");
1672                 let bounds = cx
1673                     .tcx
1674                     .explicit_item_bounds(def_id)
1675                     .iter()
1676                     .map(|(bound, _)| bound.subst(cx.tcx, substs))
1677                     .collect::<Vec<_>>();
1678                 let mut regions = vec![];
1679                 let mut has_sized = false;
1680                 let mut bounds = bounds
1681                     .iter()
1682                     .filter_map(|bound| {
1683                         // Note: The substs of opaque types can contain unbound variables,
1684                         // meaning that we have to use `ignore_quantifiers_with_unbound_vars` here.
1685                         let trait_ref = match bound
1686                             .bound_atom_with_opt_escaping(cx.tcx)
1687                             .skip_binder()
1688                         {
1689                             ty::PredicateAtom::Trait(tr, _constness) => {
1690                                 ty::Binder::bind(tr.trait_ref)
1691                             }
1692                             ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
1693                                 if let Some(r) = reg.clean(cx) {
1694                                     regions.push(GenericBound::Outlives(r));
1695                                 }
1696                                 return None;
1697                             }
1698                             _ => return None,
1699                         };
1700
1701                         if let Some(sized) = cx.tcx.lang_items().sized_trait() {
1702                             if trait_ref.def_id() == sized {
1703                                 has_sized = true;
1704                                 return None;
1705                             }
1706                         }
1707
1708                         let bounds: Vec<_> = bounds
1709                             .iter()
1710                             .filter_map(|bound| {
1711                                 if let ty::PredicateAtom::Projection(proj) =
1712                                     bound.bound_atom_with_opt_escaping(cx.tcx).skip_binder()
1713                                 {
1714                                     if proj.projection_ty.trait_ref(cx.tcx)
1715                                         == trait_ref.skip_binder()
1716                                     {
1717                                         Some(TypeBinding {
1718                                             name: cx
1719                                                 .tcx
1720                                                 .associated_item(proj.projection_ty.item_def_id)
1721                                                 .ident
1722                                                 .name
1723                                                 .clean(cx),
1724                                             kind: TypeBindingKind::Equality {
1725                                                 ty: proj.ty.clean(cx),
1726                                             },
1727                                         })
1728                                     } else {
1729                                         None
1730                                     }
1731                                 } else {
1732                                     None
1733                                 }
1734                             })
1735                             .collect();
1736
1737                         Some((trait_ref, &bounds[..]).clean(cx))
1738                     })
1739                     .collect::<Vec<_>>();
1740                 bounds.extend(regions);
1741                 if !has_sized && !bounds.is_empty() {
1742                     bounds.insert(0, GenericBound::maybe_sized(cx));
1743                 }
1744                 ImplTrait(bounds)
1745             }
1746
1747             ty::Closure(..) | ty::Generator(..) => Tuple(vec![]), // FIXME(pcwalton)
1748
1749             ty::Bound(..) => panic!("Bound"),
1750             ty::Placeholder(..) => panic!("Placeholder"),
1751             ty::GeneratorWitness(..) => panic!("GeneratorWitness"),
1752             ty::Infer(..) => panic!("Infer"),
1753             ty::Error(_) => panic!("Error"),
1754         }
1755     }
1756 }
1757
1758 impl<'tcx> Clean<Constant> for ty::Const<'tcx> {
1759     fn clean(&self, cx: &DocContext<'_>) -> Constant {
1760         Constant {
1761             type_: self.ty.clean(cx),
1762             expr: format!("{}", self),
1763             value: None,
1764             is_literal: false,
1765         }
1766     }
1767 }
1768
1769 impl Clean<Item> for hir::StructField<'_> {
1770     fn clean(&self, cx: &DocContext<'_>) -> Item {
1771         let what_rustc_thinks = Item::from_hir_id_and_parts(
1772             self.hir_id,
1773             Some(self.ident.name),
1774             StructFieldItem(self.ty.clean(cx)),
1775             cx,
1776         );
1777         // Don't show `pub` for fields on enum variants; they are always public
1778         Item { visibility: self.vis.clean(cx), ..what_rustc_thinks }
1779     }
1780 }
1781
1782 impl Clean<Item> for ty::FieldDef {
1783     fn clean(&self, cx: &DocContext<'_>) -> Item {
1784         let what_rustc_thinks = Item::from_def_id_and_parts(
1785             self.did,
1786             Some(self.ident.name.clean(cx)),
1787             StructFieldItem(cx.tcx.type_of(self.did).clean(cx)),
1788             cx,
1789         );
1790         // Don't show `pub` for fields on enum variants; they are always public
1791         Item { visibility: self.vis.clean(cx), ..what_rustc_thinks }
1792     }
1793 }
1794
1795 impl Clean<Visibility> for hir::Visibility<'_> {
1796     fn clean(&self, cx: &DocContext<'_>) -> Visibility {
1797         match self.node {
1798             hir::VisibilityKind::Public => Visibility::Public,
1799             hir::VisibilityKind::Inherited => Visibility::Inherited,
1800             hir::VisibilityKind::Crate(_) => {
1801                 let krate = DefId::local(CRATE_DEF_INDEX);
1802                 Visibility::Restricted(krate, cx.tcx.def_path(krate))
1803             }
1804             hir::VisibilityKind::Restricted { ref path, .. } => {
1805                 let path = path.clean(cx);
1806                 let did = register_res(cx, path.res);
1807                 Visibility::Restricted(did, cx.tcx.def_path(did))
1808             }
1809         }
1810     }
1811 }
1812
1813 impl Clean<Visibility> for ty::Visibility {
1814     fn clean(&self, cx: &DocContext<'_>) -> Visibility {
1815         match *self {
1816             ty::Visibility::Public => Visibility::Public,
1817             ty::Visibility::Invisible => Visibility::Inherited,
1818             ty::Visibility::Restricted(module) => {
1819                 Visibility::Restricted(module, cx.tcx.def_path(module))
1820             }
1821         }
1822     }
1823 }
1824
1825 impl Clean<VariantStruct> for rustc_hir::VariantData<'_> {
1826     fn clean(&self, cx: &DocContext<'_>) -> VariantStruct {
1827         VariantStruct {
1828             struct_type: doctree::struct_type_from_def(self),
1829             fields: self.fields().iter().map(|x| x.clean(cx)).collect(),
1830             fields_stripped: false,
1831         }
1832     }
1833 }
1834
1835 impl Clean<Item> for doctree::Variant<'_> {
1836     fn clean(&self, cx: &DocContext<'_>) -> Item {
1837         let what_rustc_thinks = Item::from_hir_id_and_parts(
1838             self.id,
1839             Some(self.name),
1840             VariantItem(Variant { kind: self.def.clean(cx) }),
1841             cx,
1842         );
1843         // don't show `pub` for variants, which are always public
1844         Item { visibility: Inherited, ..what_rustc_thinks }
1845     }
1846 }
1847
1848 impl Clean<Item> for ty::VariantDef {
1849     fn clean(&self, cx: &DocContext<'_>) -> Item {
1850         let kind = match self.ctor_kind {
1851             CtorKind::Const => VariantKind::CLike,
1852             CtorKind::Fn => VariantKind::Tuple(
1853                 self.fields.iter().map(|f| cx.tcx.type_of(f.did).clean(cx)).collect(),
1854             ),
1855             CtorKind::Fictive => VariantKind::Struct(VariantStruct {
1856                 struct_type: doctree::Plain,
1857                 fields_stripped: false,
1858                 fields: self
1859                     .fields
1860                     .iter()
1861                     .map(|field| {
1862                         let name = Some(field.ident.name.clean(cx));
1863                         let kind = StructFieldItem(cx.tcx.type_of(field.did).clean(cx));
1864                         let what_rustc_thinks =
1865                             Item::from_def_id_and_parts(field.did, name, kind, cx);
1866                         // don't show `pub` for fields, which are always public
1867                         Item { visibility: Visibility::Inherited, ..what_rustc_thinks }
1868                     })
1869                     .collect(),
1870             }),
1871         };
1872         let what_rustc_thinks = Item::from_def_id_and_parts(
1873             self.def_id,
1874             Some(self.ident.name.clean(cx)),
1875             VariantItem(Variant { kind }),
1876             cx,
1877         );
1878         // don't show `pub` for fields, which are always public
1879         Item { visibility: Inherited, ..what_rustc_thinks }
1880     }
1881 }
1882
1883 impl Clean<VariantKind> for hir::VariantData<'_> {
1884     fn clean(&self, cx: &DocContext<'_>) -> VariantKind {
1885         match self {
1886             hir::VariantData::Struct(..) => VariantKind::Struct(self.clean(cx)),
1887             hir::VariantData::Tuple(..) => {
1888                 VariantKind::Tuple(self.fields().iter().map(|x| x.ty.clean(cx)).collect())
1889             }
1890             hir::VariantData::Unit(..) => VariantKind::CLike,
1891         }
1892     }
1893 }
1894
1895 impl Clean<Span> for rustc_span::Span {
1896     fn clean(&self, cx: &DocContext<'_>) -> Span {
1897         if self.is_dummy() {
1898             return Span::empty();
1899         }
1900
1901         // Get the macro invocation instead of the definition,
1902         // in case the span is result of a macro expansion.
1903         // (See rust-lang/rust#39726)
1904         let span = self.source_callsite();
1905
1906         let sm = cx.sess().source_map();
1907         let filename = sm.span_to_filename(span);
1908         let lo = sm.lookup_char_pos(span.lo());
1909         let hi = sm.lookup_char_pos(span.hi());
1910         Span {
1911             filename,
1912             cnum: lo.file.cnum,
1913             loline: lo.line,
1914             locol: lo.col.to_usize(),
1915             hiline: hi.line,
1916             hicol: hi.col.to_usize(),
1917             original: span,
1918         }
1919     }
1920 }
1921
1922 impl Clean<Path> for hir::Path<'_> {
1923     fn clean(&self, cx: &DocContext<'_>) -> Path {
1924         Path {
1925             global: self.is_global(),
1926             res: self.res,
1927             segments: if self.is_global() { &self.segments[1..] } else { &self.segments }.clean(cx),
1928         }
1929     }
1930 }
1931
1932 impl Clean<GenericArgs> for hir::GenericArgs<'_> {
1933     fn clean(&self, cx: &DocContext<'_>) -> GenericArgs {
1934         if self.parenthesized {
1935             let output = self.bindings[0].ty().clean(cx);
1936             GenericArgs::Parenthesized {
1937                 inputs: self.inputs().clean(cx),
1938                 output: if output != Type::Tuple(Vec::new()) { Some(output) } else { None },
1939             }
1940         } else {
1941             GenericArgs::AngleBracketed {
1942                 args: self
1943                     .args
1944                     .iter()
1945                     .map(|arg| match arg {
1946                         hir::GenericArg::Lifetime(lt) if !lt.is_elided() => {
1947                             GenericArg::Lifetime(lt.clean(cx))
1948                         }
1949                         hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
1950                         hir::GenericArg::Type(ty) => GenericArg::Type(ty.clean(cx)),
1951                         hir::GenericArg::Const(ct) => GenericArg::Const(ct.clean(cx)),
1952                     })
1953                     .collect(),
1954                 bindings: self.bindings.clean(cx),
1955             }
1956         }
1957     }
1958 }
1959
1960 impl Clean<PathSegment> for hir::PathSegment<'_> {
1961     fn clean(&self, cx: &DocContext<'_>) -> PathSegment {
1962         PathSegment { name: self.ident.name.clean(cx), args: self.generic_args().clean(cx) }
1963     }
1964 }
1965
1966 impl Clean<String> for Ident {
1967     #[inline]
1968     fn clean(&self, cx: &DocContext<'_>) -> String {
1969         self.name.clean(cx)
1970     }
1971 }
1972
1973 impl Clean<String> for Symbol {
1974     #[inline]
1975     fn clean(&self, _: &DocContext<'_>) -> String {
1976         self.to_string()
1977     }
1978 }
1979
1980 impl Clean<BareFunctionDecl> for hir::BareFnTy<'_> {
1981     fn clean(&self, cx: &DocContext<'_>) -> BareFunctionDecl {
1982         let (generic_params, decl) = enter_impl_trait(cx, || {
1983             (self.generic_params.clean(cx), (&*self.decl, &self.param_names[..]).clean(cx))
1984         });
1985         BareFunctionDecl { unsafety: self.unsafety, abi: self.abi, decl, generic_params }
1986     }
1987 }
1988
1989 impl Clean<Vec<Item>> for (&hir::Item<'_>, Option<Ident>) {
1990     fn clean(&self, cx: &DocContext<'_>) -> Vec<Item> {
1991         use hir::ItemKind;
1992
1993         let (item, renamed) = self;
1994         let def_id = cx.tcx.hir().local_def_id(item.hir_id).to_def_id();
1995         let mut name = match renamed {
1996             Some(ident) => ident.name,
1997             None => cx.tcx.hir().name(item.hir_id),
1998         };
1999         cx.with_param_env(def_id, || {
2000             let kind = match item.kind {
2001                 ItemKind::Static(ty, mutability, body_id) => StaticItem(Static {
2002                     type_: ty.clean(cx),
2003                     mutability,
2004                     expr: print_const_expr(cx, body_id),
2005                 }),
2006                 ItemKind::Const(ty, body_id) => ConstantItem(Constant {
2007                     type_: ty.clean(cx),
2008                     expr: print_const_expr(cx, body_id),
2009                     value: print_evaluated_const(cx, def_id),
2010                     is_literal: is_literal_expr(cx, body_id.hir_id),
2011                 }),
2012                 ItemKind::OpaqueTy(ref ty) => OpaqueTyItem(OpaqueTy {
2013                     bounds: ty.bounds.clean(cx),
2014                     generics: ty.generics.clean(cx),
2015                 }),
2016                 ItemKind::TyAlias(ty, ref generics) => {
2017                     let rustdoc_ty = ty.clean(cx);
2018                     let item_type = rustdoc_ty.def_id().and_then(|did| inline::build_ty(cx, did));
2019                     TypedefItem(
2020                         Typedef { type_: rustdoc_ty, generics: generics.clean(cx), item_type },
2021                         false,
2022                     )
2023                 }
2024                 ItemKind::Enum(ref def, ref generics) => EnumItem(Enum {
2025                     variants: def.variants.iter().map(|v| v.clean(cx)).collect(),
2026                     generics: generics.clean(cx),
2027                     variants_stripped: false,
2028                 }),
2029                 ItemKind::TraitAlias(ref generics, bounds) => TraitAliasItem(TraitAlias {
2030                     generics: generics.clean(cx),
2031                     bounds: bounds.clean(cx),
2032                 }),
2033                 ItemKind::Union(ref variant_data, ref generics) => UnionItem(Union {
2034                     struct_type: doctree::struct_type_from_def(&variant_data),
2035                     generics: generics.clean(cx),
2036                     fields: variant_data.fields().clean(cx),
2037                     fields_stripped: false,
2038                 }),
2039                 ItemKind::Struct(ref variant_data, ref generics) => StructItem(Struct {
2040                     struct_type: doctree::struct_type_from_def(&variant_data),
2041                     generics: generics.clean(cx),
2042                     fields: variant_data.fields().clean(cx),
2043                     fields_stripped: false,
2044                 }),
2045                 ItemKind::Impl { .. } => return clean_impl(item, cx),
2046                 // proc macros can have a name set by attributes
2047                 ItemKind::Fn(ref sig, ref generics, body_id) => {
2048                     clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
2049                 }
2050                 hir::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref item_ids) => {
2051                     let items = item_ids
2052                         .iter()
2053                         .map(|ti| cx.tcx.hir().trait_item(ti.id).clean(cx))
2054                         .collect();
2055                     let attrs = item.attrs.clean(cx);
2056                     let is_spotlight = attrs.has_doc_flag(sym::spotlight);
2057                     TraitItem(Trait {
2058                         unsafety,
2059                         items,
2060                         generics: generics.clean(cx),
2061                         bounds: bounds.clean(cx),
2062                         is_spotlight,
2063                         is_auto: is_auto.clean(cx),
2064                     })
2065                 }
2066                 ItemKind::ExternCrate(orig_name) => {
2067                     return clean_extern_crate(item, name, orig_name, cx);
2068                 }
2069                 _ => unreachable!("not yet converted"),
2070             };
2071
2072             vec![Item::from_def_id_and_parts(def_id, Some(name.clean(cx)), kind, cx)]
2073         })
2074     }
2075 }
2076
2077 impl Clean<Item> for hir::Variant<'_> {
2078     fn clean(&self, cx: &DocContext<'_>) -> Item {
2079         let kind = VariantItem(Variant { kind: self.data.clean(cx) });
2080         let what_rustc_thinks =
2081             Item::from_hir_id_and_parts(self.id, Some(self.ident.name), kind, cx);
2082         // don't show `pub` for variants, which are always public
2083         Item { visibility: Inherited, ..what_rustc_thinks }
2084     }
2085 }
2086
2087 impl Clean<ImplPolarity> for ty::ImplPolarity {
2088     fn clean(&self, _: &DocContext<'_>) -> ImplPolarity {
2089         match self {
2090             &ty::ImplPolarity::Positive |
2091             // FIXME: do we want to do something else here?
2092             &ty::ImplPolarity::Reservation => ImplPolarity::Positive,
2093             &ty::ImplPolarity::Negative => ImplPolarity::Negative,
2094         }
2095     }
2096 }
2097
2098 fn clean_impl(impl_: &hir::Item<'_>, cx: &DocContext<'_>) -> Vec<Item> {
2099     let mut ret = Vec::new();
2100     let (trait_, items, for_, unsafety, generics) = match &impl_.kind {
2101         hir::ItemKind::Impl { of_trait, items, self_ty, unsafety, generics, .. } => {
2102             (of_trait, items, self_ty, *unsafety, generics)
2103         }
2104         _ => unreachable!(),
2105     };
2106     let trait_ = trait_.clean(cx);
2107     let items = items.iter().map(|ii| cx.tcx.hir().impl_item(ii.id).clean(cx)).collect::<Vec<_>>();
2108     let def_id = cx.tcx.hir().local_def_id(impl_.hir_id);
2109
2110     // If this impl block is an implementation of the Deref trait, then we
2111     // need to try inlining the target's inherent impl blocks as well.
2112     if trait_.def_id() == cx.tcx.lang_items().deref_trait() {
2113         build_deref_target_impls(cx, &items, &mut ret);
2114     }
2115
2116     let provided: FxHashSet<String> = trait_
2117         .def_id()
2118         .map(|did| cx.tcx.provided_trait_methods(did).map(|meth| meth.ident.to_string()).collect())
2119         .unwrap_or_default();
2120
2121     let for_ = for_.clean(cx);
2122     let type_alias = for_.def_id().and_then(|did| match cx.tcx.def_kind(did) {
2123         DefKind::TyAlias => Some(cx.tcx.type_of(did).clean(cx)),
2124         _ => None,
2125     });
2126     let make_item = |trait_: Option<Type>, for_: Type, items: Vec<Item>| {
2127         let kind = ImplItem(Impl {
2128             unsafety,
2129             generics: generics.clean(cx),
2130             provided_trait_methods: provided.clone(),
2131             trait_,
2132             for_,
2133             items,
2134             polarity: Some(cx.tcx.impl_polarity(def_id).clean(cx)),
2135             synthetic: false,
2136             blanket_impl: None,
2137         });
2138         Item::from_hir_id_and_parts(impl_.hir_id, None, kind, cx)
2139     };
2140     if let Some(type_alias) = type_alias {
2141         ret.push(make_item(trait_.clone(), type_alias, items.clone()));
2142     }
2143     ret.push(make_item(trait_, for_, items));
2144     ret
2145 }
2146
2147 fn clean_extern_crate(
2148     krate: &hir::Item<'_>,
2149     name: Symbol,
2150     orig_name: Option<Symbol>,
2151     cx: &DocContext<'_>,
2152 ) -> Vec<Item> {
2153     // this is the ID of the `extern crate` statement
2154     let def_id = cx.tcx.hir().local_def_id(krate.hir_id);
2155     let cnum = cx.tcx.extern_mod_stmt_cnum(def_id).unwrap_or(LOCAL_CRATE);
2156     // this is the ID of the crate itself
2157     let crate_def_id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
2158     let please_inline = krate.vis.node.is_pub()
2159         && krate.attrs.iter().any(|a| {
2160             a.has_name(sym::doc)
2161                 && match a.meta_item_list() {
2162                     Some(l) => attr::list_contains_name(&l, sym::inline),
2163                     None => false,
2164                 }
2165         });
2166
2167     if please_inline {
2168         let mut visited = FxHashSet::default();
2169
2170         let res = Res::Def(DefKind::Mod, crate_def_id);
2171
2172         if let Some(items) = inline::try_inline(
2173             cx,
2174             cx.tcx.parent_module(krate.hir_id).to_def_id(),
2175             res,
2176             name,
2177             Some(krate.attrs),
2178             &mut visited,
2179         ) {
2180             return items;
2181         }
2182     }
2183     let path = orig_name.map(|x| x.to_string());
2184     // FIXME: using `from_def_id_and_kind` breaks `rustdoc/masked` for some reason
2185     vec![Item {
2186         name: None,
2187         attrs: krate.attrs.clean(cx),
2188         source: krate.span.clean(cx),
2189         def_id: crate_def_id,
2190         visibility: krate.vis.clean(cx),
2191         stability: None,
2192         const_stability: None,
2193         deprecation: None,
2194         kind: ExternCrateItem(name.clean(cx), path),
2195     }]
2196 }
2197
2198 impl Clean<Vec<Item>> for doctree::Import<'_> {
2199     fn clean(&self, cx: &DocContext<'_>) -> Vec<Item> {
2200         // We need this comparison because some imports (for std types for example)
2201         // are "inserted" as well but directly by the compiler and they should not be
2202         // taken into account.
2203         if self.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
2204             return Vec::new();
2205         }
2206
2207         // We consider inlining the documentation of `pub use` statements, but we
2208         // forcefully don't inline if this is not public or if the
2209         // #[doc(no_inline)] attribute is present.
2210         // Don't inline doc(hidden) imports so they can be stripped at a later stage.
2211         let mut denied = !self.vis.node.is_pub()
2212             || self.attrs.iter().any(|a| {
2213                 a.has_name(sym::doc)
2214                     && match a.meta_item_list() {
2215                         Some(l) => {
2216                             attr::list_contains_name(&l, sym::no_inline)
2217                                 || attr::list_contains_name(&l, sym::hidden)
2218                         }
2219                         None => false,
2220                     }
2221             });
2222         // Also check whether imports were asked to be inlined, in case we're trying to re-export a
2223         // crate in Rust 2018+
2224         let please_inline = self.attrs.lists(sym::doc).has_word(sym::inline);
2225         let path = self.path.clean(cx);
2226         let inner = if self.glob {
2227             if !denied {
2228                 let mut visited = FxHashSet::default();
2229                 if let Some(items) = inline::try_inline_glob(cx, path.res, &mut visited) {
2230                     return items;
2231                 }
2232             }
2233             Import::new_glob(resolve_use_source(cx, path), true)
2234         } else {
2235             let name = self.name;
2236             if !please_inline {
2237                 if let Res::Def(DefKind::Mod, did) = path.res {
2238                     if !did.is_local() && did.index == CRATE_DEF_INDEX {
2239                         // if we're `pub use`ing an extern crate root, don't inline it unless we
2240                         // were specifically asked for it
2241                         denied = true;
2242                     }
2243                 }
2244             }
2245             if !denied {
2246                 let mut visited = FxHashSet::default();
2247
2248                 if let Some(mut items) = inline::try_inline(
2249                     cx,
2250                     cx.tcx.parent_module(self.id).to_def_id(),
2251                     path.res,
2252                     name,
2253                     Some(self.attrs),
2254                     &mut visited,
2255                 ) {
2256                     items.push(Item {
2257                         name: None,
2258                         attrs: self.attrs.clean(cx),
2259                         source: self.span.clean(cx),
2260                         def_id: cx.tcx.hir().local_def_id(self.id).to_def_id(),
2261                         visibility: self.vis.clean(cx),
2262                         stability: None,
2263                         const_stability: None,
2264                         deprecation: None,
2265                         kind: ImportItem(Import::new_simple(
2266                             self.name.clean(cx),
2267                             resolve_use_source(cx, path),
2268                             false,
2269                         )),
2270                     });
2271                     return items;
2272                 }
2273             }
2274             Import::new_simple(name.clean(cx), resolve_use_source(cx, path), true)
2275         };
2276
2277         vec![Item {
2278             name: None,
2279             attrs: self.attrs.clean(cx),
2280             source: self.span.clean(cx),
2281             def_id: DefId::local(CRATE_DEF_INDEX),
2282             visibility: self.vis.clean(cx),
2283             stability: None,
2284             const_stability: None,
2285             deprecation: None,
2286             kind: ImportItem(inner),
2287         }]
2288     }
2289 }
2290
2291 impl Clean<Item> for (&hir::ForeignItem<'_>, Option<Ident>) {
2292     fn clean(&self, cx: &DocContext<'_>) -> Item {
2293         let (item, renamed) = self;
2294         cx.with_param_env(cx.tcx.hir().local_def_id(item.hir_id).to_def_id(), || {
2295             let kind = match item.kind {
2296                 hir::ForeignItemKind::Fn(ref decl, ref names, ref generics) => {
2297                     let abi = cx.tcx.hir().get_foreign_abi(item.hir_id);
2298                     let (generics, decl) = enter_impl_trait(cx, || {
2299                         (generics.clean(cx), (&**decl, &names[..]).clean(cx))
2300                     });
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, mutability) => ForeignStaticItem(Static {
2316                     type_: ty.clean(cx),
2317                     mutability,
2318                     expr: String::new(),
2319                 }),
2320                 hir::ForeignItemKind::Type => ForeignTypeItem,
2321             };
2322
2323             Item::from_hir_id_and_parts(
2324                 item.hir_id,
2325                 Some(renamed.unwrap_or(item.ident).name),
2326                 kind,
2327                 cx,
2328             )
2329         })
2330     }
2331 }
2332
2333 impl Clean<Item> for (&hir::MacroDef<'_>, Option<Ident>) {
2334     fn clean(&self, cx: &DocContext<'_>) -> Item {
2335         let (item, renamed) = self;
2336         let name = renamed.unwrap_or(item.ident).name;
2337         let tts = item.ast.body.inner_tokens().trees().collect::<Vec<_>>();
2338         // Extract the spans of all matchers. They represent the "interface" of the macro.
2339         let matchers = tts.chunks(4).map(|arm| arm[0].span()).collect::<Vec<_>>();
2340         let source = if item.ast.macro_rules {
2341             format!(
2342                 "macro_rules! {} {{\n{}}}",
2343                 name,
2344                 matchers
2345                     .iter()
2346                     .map(|span| { format!("    {} => {{ ... }};\n", span.to_src(cx)) })
2347                     .collect::<String>(),
2348             )
2349         } else {
2350             let vis = item.vis.clean(cx);
2351
2352             if matchers.len() <= 1 {
2353                 format!(
2354                     "{}macro {}{} {{\n    ...\n}}",
2355                     vis.print_with_space(),
2356                     name,
2357                     matchers.iter().map(|span| span.to_src(cx)).collect::<String>(),
2358                 )
2359             } else {
2360                 format!(
2361                     "{}macro {} {{\n{}}}",
2362                     vis.print_with_space(),
2363                     name,
2364                     matchers
2365                         .iter()
2366                         .map(|span| { format!("    {} => {{ ... }},\n", span.to_src(cx)) })
2367                         .collect::<String>(),
2368                 )
2369             }
2370         };
2371
2372         Item::from_hir_id_and_parts(
2373             item.hir_id,
2374             Some(name),
2375             MacroItem(Macro { source, imported_from: None }),
2376             cx,
2377         )
2378     }
2379 }
2380
2381 impl Clean<Deprecation> for attr::Deprecation {
2382     fn clean(&self, _: &DocContext<'_>) -> Deprecation {
2383         Deprecation {
2384             since: self.since.map(|s| s.to_string()).filter(|s| !s.is_empty()),
2385             note: self.note.map(|n| n.to_string()).filter(|n| !n.is_empty()),
2386             is_since_rustc_version: self.is_since_rustc_version,
2387         }
2388     }
2389 }
2390
2391 impl Clean<TypeBinding> for hir::TypeBinding<'_> {
2392     fn clean(&self, cx: &DocContext<'_>) -> TypeBinding {
2393         TypeBinding { name: self.ident.name.clean(cx), kind: self.kind.clean(cx) }
2394     }
2395 }
2396
2397 impl Clean<TypeBindingKind> for hir::TypeBindingKind<'_> {
2398     fn clean(&self, cx: &DocContext<'_>) -> TypeBindingKind {
2399         match *self {
2400             hir::TypeBindingKind::Equality { ref ty } => {
2401                 TypeBindingKind::Equality { ty: ty.clean(cx) }
2402             }
2403             hir::TypeBindingKind::Constraint { ref bounds } => {
2404                 TypeBindingKind::Constraint { bounds: bounds.iter().map(|b| b.clean(cx)).collect() }
2405             }
2406         }
2407     }
2408 }
2409
2410 enum SimpleBound {
2411     TraitBound(Vec<PathSegment>, Vec<SimpleBound>, Vec<GenericParamDef>, hir::TraitBoundModifier),
2412     Outlives(Lifetime),
2413 }
2414
2415 impl From<GenericBound> for SimpleBound {
2416     fn from(bound: GenericBound) -> Self {
2417         match bound.clone() {
2418             GenericBound::Outlives(l) => SimpleBound::Outlives(l),
2419             GenericBound::TraitBound(t, mod_) => match t.trait_ {
2420                 Type::ResolvedPath { path, param_names, .. } => SimpleBound::TraitBound(
2421                     path.segments,
2422                     param_names.map_or_else(Vec::new, |v| {
2423                         v.iter().map(|p| SimpleBound::from(p.clone())).collect()
2424                     }),
2425                     t.generic_params,
2426                     mod_,
2427                 ),
2428                 _ => panic!("Unexpected bound {:?}", bound),
2429             },
2430         }
2431     }
2432 }