src/librustdoc/clean/mod.rs

   1 //! This module contains the "cleaned" pieces of the AST, and the functions
   2 //! that clean them.
   3
   4 mod auto_trait;
   5 mod blanket_impl;
   6 pub(crate) mod cfg;
   7 pub(crate) mod inline;
   8 mod render_macro_matchers;
   9 mod simplify;
  10 pub(crate) mod types;
  11 pub(crate) mod utils;
  12
  13 use rustc_ast as ast;
  14 use rustc_attr as attr;
  15 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  16 use rustc_hir as hir;
  17 use rustc_hir::def::{CtorKind, DefKind, Res};
  18 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
  19 use rustc_hir::PredicateOrigin;
  20 use rustc_infer::infer::region_constraints::{Constraint, RegionConstraintData};
  21 use rustc_middle::middle::resolve_lifetime as rl;
  22 use rustc_middle::ty::fold::TypeFolder;
  23 use rustc_middle::ty::subst::{InternalSubsts, Subst};
  24 use rustc_middle::ty::{self, AdtKind, DefIdTree, EarlyBinder, Lift, Ty, TyCtxt};
  25 use rustc_middle::{bug, span_bug};
  26 use rustc_span::hygiene::{AstPass, MacroKind};
  27 use rustc_span::symbol::{kw, sym, Ident, Symbol};
  28 use rustc_span::{self, ExpnKind};
  29 use rustc_typeck::hir_ty_to_ty;
  30
  31 use std::assert_matches::assert_matches;
  32 use std::collections::hash_map::Entry;
  33 use std::collections::BTreeMap;
  34 use std::default::Default;
  35 use std::hash::Hash;
  36 use std::{mem, vec};
  37
  38 use crate::core::{self, DocContext, ImplTraitParam};
  39 use crate::formats::item_type::ItemType;
  40 use crate::visit_ast::Module as DocModule;
  41
  42 use utils::*;
  43
  44 pub(crate) use self::types::*;
  45 pub(crate) use self::utils::{get_auto_trait_and_blanket_impls, krate, register_res};
  46
  47 pub(crate) trait Clean<'tcx, T> {
  48     fn clean(&self, cx: &mut DocContext<'tcx>) -> T;
  49 }
  50
  51 pub(crate) fn clean_doc_module<'tcx>(doc: &DocModule<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
  52     let mut items: Vec<Item> = vec![];
  53     let mut inserted = FxHashSet::default();
  54     items.extend(doc.foreigns.iter().map(|(item, renamed)| {
  55         let item = clean_maybe_renamed_foreign_item(cx, item, *renamed);
  56         if let Some(name) = item.name {
  57             inserted.insert((item.type_(), name));
  58         }
  59         item
  60     }));
  61     items.extend(doc.mods.iter().map(|x| {
  62         inserted.insert((ItemType::Module, x.name));
  63         clean_doc_module(x, cx)
  64     }));
  65
  66     // Split up imports from all other items.
  67     //
  68     // This covers the case where somebody does an import which should pull in an item,
  69     // but there's already an item with the same namespace and same name. Rust gives
  70     // priority to the not-imported one, so we should, too.
  71     items.extend(doc.items.iter().flat_map(|(item, renamed)| {
  72         // First, lower everything other than imports.
  73         if matches!(item.kind, hir::ItemKind::Use(_, hir::UseKind::Glob)) {
  74             return Vec::new();
  75         }
  76         let v = clean_maybe_renamed_item(cx, item, *renamed);
  77         for item in &v {
  78             if let Some(name) = item.name {
  79                 inserted.insert((item.type_(), name));
  80             }
  81         }
  82         v
  83     }));
  84     items.extend(doc.items.iter().flat_map(|(item, renamed)| {
  85         // Now we actually lower the imports, skipping everything else.
  86         if let hir::ItemKind::Use(path, hir::UseKind::Glob) = item.kind {
  87             let name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
  88             clean_use_statement(item, name, path, hir::UseKind::Glob, cx, &mut inserted)
  89         } else {
  90             // skip everything else
  91             Vec::new()
  92         }
  93     }));
  94
  95     // determine if we should display the inner contents or
  96     // the outer `mod` item for the source code.
  97
  98     let span = Span::new({
  99         let where_outer = doc.where_outer(cx.tcx);
 100         let sm = cx.sess().source_map();
 101         let outer = sm.lookup_char_pos(where_outer.lo());
 102         let inner = sm.lookup_char_pos(doc.where_inner.lo());
 103         if outer.file.start_pos == inner.file.start_pos {
 104             // mod foo { ... }
 105             where_outer
 106         } else {
 107             // mod foo; (and a separate SourceFile for the contents)
 108             doc.where_inner
 109         }
 110     });
 111
 112     Item::from_hir_id_and_parts(doc.id, Some(doc.name), ModuleItem(Module { items, span }), cx)
 113 }
 114
 115 fn clean_generic_bound<'tcx>(
 116     bound: &hir::GenericBound<'tcx>,
 117     cx: &mut DocContext<'tcx>,
 118 ) -> Option<GenericBound> {
 119     Some(match *bound {
 120         hir::GenericBound::Outlives(lt) => GenericBound::Outlives(clean_lifetime(lt, cx)),
 121         hir::GenericBound::LangItemTrait(lang_item, span, _, generic_args) => {
 122             let def_id = cx.tcx.require_lang_item(lang_item, Some(span));
 123
 124             let trait_ref = ty::TraitRef::identity(cx.tcx, def_id).skip_binder();
 125
 126             let generic_args = clean_generic_args(generic_args, cx);
 127             let GenericArgs::AngleBracketed { bindings, .. } = generic_args
 128             else {
 129                 bug!("clean: parenthesized `GenericBound::LangItemTrait`");
 130             };
 131
 132             let trait_ = clean_trait_ref_with_bindings(cx, trait_ref, &bindings);
 133             GenericBound::TraitBound(
 134                 PolyTrait { trait_, generic_params: vec![] },
 135                 hir::TraitBoundModifier::None,
 136             )
 137         }
 138         hir::GenericBound::Trait(ref t, modifier) => {
 139             // `T: ~const Destruct` is hidden because `T: Destruct` is a no-op.
 140             if modifier == hir::TraitBoundModifier::MaybeConst
 141                 && cx.tcx.lang_items().destruct_trait() == Some(t.trait_ref.trait_def_id().unwrap())
 142             {
 143                 return None;
 144             }
 145
 146             GenericBound::TraitBound(clean_poly_trait_ref(t, cx), modifier)
 147         }
 148     })
 149 }
 150
 151 pub(crate) fn clean_trait_ref_with_bindings<'tcx>(
 152     cx: &mut DocContext<'tcx>,
 153     trait_ref: ty::TraitRef<'tcx>,
 154     bindings: &[TypeBinding],
 155 ) -> Path {
 156     let kind = cx.tcx.def_kind(trait_ref.def_id).into();
 157     if !matches!(kind, ItemType::Trait | ItemType::TraitAlias) {
 158         span_bug!(cx.tcx.def_span(trait_ref.def_id), "`TraitRef` had unexpected kind {:?}", kind);
 159     }
 160     inline::record_extern_fqn(cx, trait_ref.def_id, kind);
 161     let path = external_path(cx, trait_ref.def_id, true, bindings.to_vec(), trait_ref.substs);
 162
 163     debug!("ty::TraitRef\n  subst: {:?}\n", trait_ref.substs);
 164
 165     path
 166 }
 167
 168 fn clean_poly_trait_ref_with_bindings<'tcx>(
 169     cx: &mut DocContext<'tcx>,
 170     poly_trait_ref: ty::PolyTraitRef<'tcx>,
 171     bindings: &[TypeBinding],
 172 ) -> GenericBound {
 173     let poly_trait_ref = poly_trait_ref.lift_to_tcx(cx.tcx).unwrap();
 174
 175     // collect any late bound regions
 176     let late_bound_regions: Vec<_> = cx
 177         .tcx
 178         .collect_referenced_late_bound_regions(&poly_trait_ref)
 179         .into_iter()
 180         .filter_map(|br| match br {
 181             ty::BrNamed(_, name) if name != kw::UnderscoreLifetime => Some(GenericParamDef {
 182                 name,
 183                 kind: GenericParamDefKind::Lifetime { outlives: vec![] },
 184             }),
 185             _ => None,
 186         })
 187         .collect();
 188
 189     let trait_ = clean_trait_ref_with_bindings(cx, poly_trait_ref.skip_binder(), bindings);
 190     GenericBound::TraitBound(
 191         PolyTrait { trait_, generic_params: late_bound_regions },
 192         hir::TraitBoundModifier::None,
 193     )
 194 }
 195
 196 fn clean_lifetime<'tcx>(lifetime: hir::Lifetime, cx: &mut DocContext<'tcx>) -> Lifetime {
 197     let def = cx.tcx.named_region(lifetime.hir_id);
 198     if let Some(
 199         rl::Region::EarlyBound(_, node_id)
 200         | rl::Region::LateBound(_, _, node_id)
 201         | rl::Region::Free(_, node_id),
 202     ) = def
 203     {
 204         if let Some(lt) = cx.substs.get(&node_id).and_then(|p| p.as_lt()).cloned() {
 205             return lt;
 206         }
 207     }
 208     Lifetime(lifetime.name.ident().name)
 209 }
 210
 211 pub(crate) fn clean_const<'tcx>(constant: &hir::ConstArg, cx: &mut DocContext<'tcx>) -> Constant {
 212     let def_id = cx.tcx.hir().body_owner_def_id(constant.value.body).to_def_id();
 213     Constant {
 214         type_: clean_middle_ty(cx.tcx.type_of(def_id), cx, Some(def_id)),
 215         kind: ConstantKind::Anonymous { body: constant.value.body },
 216     }
 217 }
 218
 219 pub(crate) fn clean_middle_const<'tcx>(
 220     constant: ty::Const<'tcx>,
 221     cx: &mut DocContext<'tcx>,
 222 ) -> Constant {
 223     // FIXME: instead of storing the stringified expression, store `self` directly instead.
 224     Constant {
 225         type_: clean_middle_ty(constant.ty(), cx, None),
 226         kind: ConstantKind::TyConst { expr: constant.to_string() },
 227     }
 228 }
 229
 230 pub(crate) fn clean_middle_region<'tcx>(region: ty::Region<'tcx>) -> Option<Lifetime> {
 231     match *region {
 232         ty::ReStatic => Some(Lifetime::statik()),
 233         ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => {
 234             if name != kw::UnderscoreLifetime { Some(Lifetime(name)) } else { None }
 235         }
 236         ty::ReEarlyBound(ref data) => {
 237             if data.name != kw::UnderscoreLifetime {
 238                 Some(Lifetime(data.name))
 239             } else {
 240                 None
 241             }
 242         }
 243         ty::ReLateBound(..)
 244         | ty::ReFree(..)
 245         | ty::ReVar(..)
 246         | ty::RePlaceholder(..)
 247         | ty::ReEmpty(_)
 248         | ty::ReErased => {
 249             debug!("cannot clean region {:?}", region);
 250             None
 251         }
 252     }
 253 }
 254
 255 fn clean_where_predicate<'tcx>(
 256     predicate: &hir::WherePredicate<'tcx>,
 257     cx: &mut DocContext<'tcx>,
 258 ) -> Option<WherePredicate> {
 259     if !predicate.in_where_clause() {
 260         return None;
 261     }
 262     Some(match *predicate {
 263         hir::WherePredicate::BoundPredicate(ref wbp) => {
 264             let bound_params = wbp
 265                 .bound_generic_params
 266                 .iter()
 267                 .map(|param| {
 268                     // Higher-ranked params must be lifetimes.
 269                     // Higher-ranked lifetimes can't have bounds.
 270                     assert_matches!(
 271                         param,
 272                         hir::GenericParam { kind: hir::GenericParamKind::Lifetime { .. }, .. }
 273                     );
 274                     Lifetime(param.name.ident().name)
 275                 })
 276                 .collect();
 277             WherePredicate::BoundPredicate {
 278                 ty: clean_ty(wbp.bounded_ty, cx),
 279                 bounds: wbp.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
 280                 bound_params,
 281             }
 282         }
 283
 284         hir::WherePredicate::RegionPredicate(ref wrp) => WherePredicate::RegionPredicate {
 285             lifetime: clean_lifetime(wrp.lifetime, cx),
 286             bounds: wrp.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
 287         },
 288
 289         hir::WherePredicate::EqPredicate(ref wrp) => WherePredicate::EqPredicate {
 290             lhs: clean_ty(wrp.lhs_ty, cx),
 291             rhs: clean_ty(wrp.rhs_ty, cx).into(),
 292         },
 293     })
 294 }
 295
 296 pub(crate) fn clean_predicate<'tcx>(
 297     predicate: ty::Predicate<'tcx>,
 298     cx: &mut DocContext<'tcx>,
 299 ) -> Option<WherePredicate> {
 300     let bound_predicate = predicate.kind();
 301     match bound_predicate.skip_binder() {
 302         ty::PredicateKind::Trait(pred) => {
 303             clean_poly_trait_predicate(bound_predicate.rebind(pred), cx)
 304         }
 305         ty::PredicateKind::RegionOutlives(pred) => clean_region_outlives_predicate(pred),
 306         ty::PredicateKind::TypeOutlives(pred) => clean_type_outlives_predicate(pred, cx),
 307         ty::PredicateKind::Projection(pred) => Some(clean_projection_predicate(pred, cx)),
 308         ty::PredicateKind::ConstEvaluatable(..) => None,
 309         ty::PredicateKind::WellFormed(..) => None,
 310
 311         ty::PredicateKind::Subtype(..)
 312         | ty::PredicateKind::Coerce(..)
 313         | ty::PredicateKind::ObjectSafe(..)
 314         | ty::PredicateKind::ClosureKind(..)
 315         | ty::PredicateKind::ConstEquate(..)
 316         | ty::PredicateKind::TypeWellFormedFromEnv(..) => panic!("not user writable"),
 317     }
 318 }
 319
 320 fn clean_poly_trait_predicate<'tcx>(
 321     pred: ty::PolyTraitPredicate<'tcx>,
 322     cx: &mut DocContext<'tcx>,
 323 ) -> Option<WherePredicate> {
 324     // `T: ~const Destruct` is hidden because `T: Destruct` is a no-op.
 325     if pred.skip_binder().constness == ty::BoundConstness::ConstIfConst
 326         && Some(pred.skip_binder().def_id()) == cx.tcx.lang_items().destruct_trait()
 327     {
 328         return None;
 329     }
 330
 331     let poly_trait_ref = pred.map_bound(|pred| pred.trait_ref);
 332     Some(WherePredicate::BoundPredicate {
 333         ty: clean_middle_ty(poly_trait_ref.skip_binder().self_ty(), cx, None),
 334         bounds: vec![clean_poly_trait_ref_with_bindings(cx, poly_trait_ref, &[])],
 335         bound_params: Vec::new(),
 336     })
 337 }
 338
 339 fn clean_region_outlives_predicate<'tcx>(
 340     pred: ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>,
 341 ) -> Option<WherePredicate> {
 342     let ty::OutlivesPredicate(a, b) = pred;
 343
 344     if a.is_empty() && b.is_empty() {
 345         return None;
 346     }
 347
 348     Some(WherePredicate::RegionPredicate {
 349         lifetime: clean_middle_region(a).expect("failed to clean lifetime"),
 350         bounds: vec![GenericBound::Outlives(
 351             clean_middle_region(b).expect("failed to clean bounds"),
 352         )],
 353     })
 354 }
 355
 356 fn clean_type_outlives_predicate<'tcx>(
 357     pred: ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>,
 358     cx: &mut DocContext<'tcx>,
 359 ) -> Option<WherePredicate> {
 360     let ty::OutlivesPredicate(ty, lt) = pred;
 361
 362     if lt.is_empty() {
 363         return None;
 364     }
 365
 366     Some(WherePredicate::BoundPredicate {
 367         ty: clean_middle_ty(ty, cx, None),
 368         bounds: vec![GenericBound::Outlives(
 369             clean_middle_region(lt).expect("failed to clean lifetimes"),
 370         )],
 371         bound_params: Vec::new(),
 372     })
 373 }
 374
 375 fn clean_middle_term<'tcx>(term: ty::Term<'tcx>, cx: &mut DocContext<'tcx>) -> Term {
 376     match term {
 377         ty::Term::Ty(ty) => Term::Type(clean_middle_ty(ty, cx, None)),
 378         ty::Term::Const(c) => Term::Constant(clean_middle_const(c, cx)),
 379     }
 380 }
 381
 382 fn clean_hir_term<'tcx>(term: &hir::Term<'tcx>, cx: &mut DocContext<'tcx>) -> Term {
 383     match term {
 384         hir::Term::Ty(ty) => Term::Type(clean_ty(ty, cx)),
 385         hir::Term::Const(c) => {
 386             let def_id = cx.tcx.hir().local_def_id(c.hir_id);
 387             Term::Constant(clean_middle_const(ty::Const::from_anon_const(cx.tcx, def_id), cx))
 388         }
 389     }
 390 }
 391
 392 fn clean_projection_predicate<'tcx>(
 393     pred: ty::ProjectionPredicate<'tcx>,
 394     cx: &mut DocContext<'tcx>,
 395 ) -> WherePredicate {
 396     let ty::ProjectionPredicate { projection_ty, term } = pred;
 397     WherePredicate::EqPredicate {
 398         lhs: clean_projection(projection_ty, cx, None),
 399         rhs: clean_middle_term(term, cx),
 400     }
 401 }
 402
 403 fn clean_projection<'tcx>(
 404     ty: ty::ProjectionTy<'tcx>,
 405     cx: &mut DocContext<'tcx>,
 406     def_id: Option<DefId>,
 407 ) -> Type {
 408     let lifted = ty.lift_to_tcx(cx.tcx).unwrap();
 409     let trait_ = clean_trait_ref_with_bindings(cx, lifted.trait_ref(cx.tcx), &[]);
 410     let self_type = clean_middle_ty(ty.self_ty(), cx, None);
 411     let self_def_id = if let Some(def_id) = def_id {
 412         cx.tcx.opt_parent(def_id).or(Some(def_id))
 413     } else {
 414         self_type.def_id(&cx.cache)
 415     };
 416     let should_show_cast = compute_should_show_cast(self_def_id, &trait_, &self_type);
 417     Type::QPath {
 418         assoc: Box::new(projection_to_path_segment(ty, cx)),
 419         should_show_cast,
 420         self_type: Box::new(self_type),
 421         trait_,
 422     }
 423 }
 424
 425 fn compute_should_show_cast(self_def_id: Option<DefId>, trait_: &Path, self_type: &Type) -> bool {
 426     !trait_.segments.is_empty()
 427         && self_def_id
 428             .zip(Some(trait_.def_id()))
 429             .map_or(!self_type.is_self_type(), |(id, trait_)| id != trait_)
 430 }
 431
 432 fn projection_to_path_segment<'tcx>(
 433     ty: ty::ProjectionTy<'tcx>,
 434     cx: &mut DocContext<'tcx>,
 435 ) -> PathSegment {
 436     let item = cx.tcx.associated_item(ty.item_def_id);
 437     let generics = cx.tcx.generics_of(ty.item_def_id);
 438     PathSegment {
 439         name: item.name,
 440         args: GenericArgs::AngleBracketed {
 441             args: substs_to_args(cx, &ty.substs[generics.parent_count..], false).into(),
 442             bindings: Default::default(),
 443         },
 444     }
 445 }
 446
 447 fn clean_generic_param_def<'tcx>(
 448     def: &ty::GenericParamDef,
 449     cx: &mut DocContext<'tcx>,
 450 ) -> GenericParamDef {
 451     let (name, kind) = match def.kind {
 452         ty::GenericParamDefKind::Lifetime => {
 453             (def.name, GenericParamDefKind::Lifetime { outlives: vec![] })
 454         }
 455         ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
 456             let default = if has_default {
 457                 Some(clean_middle_ty(cx.tcx.type_of(def.def_id), cx, Some(def.def_id)))
 458             } else {
 459                 None
 460             };
 461             (
 462                 def.name,
 463                 GenericParamDefKind::Type {
 464                     did: def.def_id,
 465                     bounds: vec![], // These are filled in from the where-clauses.
 466                     default: default.map(Box::new),
 467                     synthetic,
 468                 },
 469             )
 470         }
 471         ty::GenericParamDefKind::Const { has_default } => (
 472             def.name,
 473             GenericParamDefKind::Const {
 474                 did: def.def_id,
 475                 ty: Box::new(clean_middle_ty(cx.tcx.type_of(def.def_id), cx, Some(def.def_id))),
 476                 default: match has_default {
 477                     true => Some(Box::new(cx.tcx.const_param_default(def.def_id).to_string())),
 478                     false => None,
 479                 },
 480             },
 481         ),
 482     };
 483
 484     GenericParamDef { name, kind }
 485 }
 486
 487 fn clean_generic_param<'tcx>(
 488     cx: &mut DocContext<'tcx>,
 489     generics: Option<&hir::Generics<'tcx>>,
 490     param: &hir::GenericParam<'tcx>,
 491 ) -> GenericParamDef {
 492     let did = cx.tcx.hir().local_def_id(param.hir_id);
 493     let (name, kind) = match param.kind {
 494         hir::GenericParamKind::Lifetime { .. } => {
 495             let outlives = if let Some(generics) = generics {
 496                 generics
 497                     .outlives_for_param(did)
 498                     .filter(|bp| !bp.in_where_clause)
 499                     .flat_map(|bp| bp.bounds)
 500                     .map(|bound| match bound {
 501                         hir::GenericBound::Outlives(lt) => clean_lifetime(*lt, cx),
 502                         _ => panic!(),
 503                     })
 504                     .collect()
 505             } else {
 506                 Vec::new()
 507             };
 508             (param.name.ident().name, GenericParamDefKind::Lifetime { outlives })
 509         }
 510         hir::GenericParamKind::Type { ref default, synthetic } => {
 511             let bounds = if let Some(generics) = generics {
 512                 generics
 513                     .bounds_for_param(did)
 514                     .filter(|bp| bp.origin != PredicateOrigin::WhereClause)
 515                     .flat_map(|bp| bp.bounds)
 516                     .filter_map(|x| clean_generic_bound(x, cx))
 517                     .collect()
 518             } else {
 519                 Vec::new()
 520             };
 521             (
 522                 param.name.ident().name,
 523                 GenericParamDefKind::Type {
 524                     did: did.to_def_id(),
 525                     bounds,
 526                     default: default.map(|t| clean_ty(t, cx)).map(Box::new),
 527                     synthetic,
 528                 },
 529             )
 530         }
 531         hir::GenericParamKind::Const { ty, default } => (
 532             param.name.ident().name,
 533             GenericParamDefKind::Const {
 534                 did: did.to_def_id(),
 535                 ty: Box::new(clean_ty(ty, cx)),
 536                 default: default.map(|ct| {
 537                     let def_id = cx.tcx.hir().local_def_id(ct.hir_id);
 538                     Box::new(ty::Const::from_anon_const(cx.tcx, def_id).to_string())
 539                 }),
 540             },
 541         ),
 542     };
 543
 544     GenericParamDef { name, kind }
 545 }
 546
 547 /// Synthetic type-parameters are inserted after normal ones.
 548 /// In order for normal parameters to be able to refer to synthetic ones,
 549 /// scans them first.
 550 fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
 551     match param.kind {
 552         hir::GenericParamKind::Type { synthetic, .. } => synthetic,
 553         _ => false,
 554     }
 555 }
 556
 557 /// This can happen for `async fn`, e.g. `async fn f<'_>(&'_ self)`.
 558 ///
 559 /// See `lifetime_to_generic_param` in `rustc_ast_lowering` for more information.
 560 fn is_elided_lifetime(param: &hir::GenericParam<'_>) -> bool {
 561     matches!(param.kind, hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided })
 562 }
 563
 564 pub(crate) fn clean_generics<'tcx>(
 565     gens: &hir::Generics<'tcx>,
 566     cx: &mut DocContext<'tcx>,
 567 ) -> Generics {
 568     let impl_trait_params = gens
 569         .params
 570         .iter()
 571         .filter(|param| is_impl_trait(param))
 572         .map(|param| {
 573             let param = clean_generic_param(cx, Some(gens), param);
 574             match param.kind {
 575                 GenericParamDefKind::Lifetime { .. } => unreachable!(),
 576                 GenericParamDefKind::Type { did, ref bounds, .. } => {
 577                     cx.impl_trait_bounds.insert(did.into(), bounds.clone());
 578                 }
 579                 GenericParamDefKind::Const { .. } => unreachable!(),
 580             }
 581             param
 582         })
 583         .collect::<Vec<_>>();
 584
 585     let mut params = Vec::with_capacity(gens.params.len());
 586     for p in gens.params.iter().filter(|p| !is_impl_trait(p) && !is_elided_lifetime(p)) {
 587         let p = clean_generic_param(cx, Some(gens), p);
 588         params.push(p);
 589     }
 590     params.extend(impl_trait_params);
 591
 592     let mut generics = Generics {
 593         params,
 594         where_predicates: gens
 595             .predicates
 596             .iter()
 597             .filter_map(|x| clean_where_predicate(x, cx))
 598             .collect(),
 599     };
 600
 601     // Some duplicates are generated for ?Sized bounds between type params and where
 602     // predicates. The point in here is to move the bounds definitions from type params
 603     // to where predicates when such cases occur.
 604     for where_pred in &mut generics.where_predicates {
 605         match *where_pred {
 606             WherePredicate::BoundPredicate { ty: Generic(ref name), ref mut bounds, .. } => {
 607                 if bounds.is_empty() {
 608                     for param in &mut generics.params {
 609                         match param.kind {
 610                             GenericParamDefKind::Lifetime { .. } => {}
 611                             GenericParamDefKind::Type { bounds: ref mut ty_bounds, .. } => {
 612                                 if &param.name == name {
 613                                     mem::swap(bounds, ty_bounds);
 614                                     break;
 615                                 }
 616                             }
 617                             GenericParamDefKind::Const { .. } => {}
 618                         }
 619                     }
 620                 }
 621             }
 622             _ => continue,
 623         }
 624     }
 625     generics
 626 }
 627
 628 fn clean_ty_generics<'tcx>(
 629     cx: &mut DocContext<'tcx>,
 630     gens: &ty::Generics,
 631     preds: ty::GenericPredicates<'tcx>,
 632 ) -> Generics {
 633     // Don't populate `cx.impl_trait_bounds` before `clean`ning `where` clauses,
 634     // since `Clean for ty::Predicate` would consume them.
 635     let mut impl_trait = BTreeMap::<ImplTraitParam, Vec<GenericBound>>::default();
 636
 637     // Bounds in the type_params and lifetimes fields are repeated in the
 638     // predicates field (see rustc_typeck::collect::ty_generics), so remove
 639     // them.
 640     let stripped_params = gens
 641         .params
 642         .iter()
 643         .filter_map(|param| match param.kind {
 644             ty::GenericParamDefKind::Lifetime if param.name == kw::UnderscoreLifetime => None,
 645             ty::GenericParamDefKind::Lifetime => Some(clean_generic_param_def(param, cx)),
 646             ty::GenericParamDefKind::Type { synthetic, .. } => {
 647                 if param.name == kw::SelfUpper {
 648                     assert_eq!(param.index, 0);
 649                     return None;
 650                 }
 651                 if synthetic {
 652                     impl_trait.insert(param.index.into(), vec![]);
 653                     return None;
 654                 }
 655                 Some(clean_generic_param_def(param, cx))
 656             }
 657             ty::GenericParamDefKind::Const { .. } => Some(clean_generic_param_def(param, cx)),
 658         })
 659         .collect::<Vec<GenericParamDef>>();
 660
 661     // param index -> [(DefId of trait, associated type name and generics, type)]
 662     let mut impl_trait_proj = FxHashMap::<u32, Vec<(DefId, PathSegment, Ty<'_>)>>::default();
 663
 664     let where_predicates = preds
 665         .predicates
 666         .iter()
 667         .flat_map(|(p, _)| {
 668             let mut projection = None;
 669             let param_idx = (|| {
 670                 let bound_p = p.kind();
 671                 match bound_p.skip_binder() {
 672                     ty::PredicateKind::Trait(pred) => {
 673                         if let ty::Param(param) = pred.self_ty().kind() {
 674                             return Some(param.index);
 675                         }
 676                     }
 677                     ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty, _reg)) => {
 678                         if let ty::Param(param) = ty.kind() {
 679                             return Some(param.index);
 680                         }
 681                     }
 682                     ty::PredicateKind::Projection(p) => {
 683                         if let ty::Param(param) = p.projection_ty.self_ty().kind() {
 684                             projection = Some(bound_p.rebind(p));
 685                             return Some(param.index);
 686                         }
 687                     }
 688                     _ => (),
 689                 }
 690
 691                 None
 692             })();
 693
 694             if let Some(param_idx) = param_idx {
 695                 if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
 696                     let p: WherePredicate = clean_predicate(*p, cx)?;
 697
 698                     b.extend(
 699                         p.get_bounds()
 700                             .into_iter()
 701                             .flatten()
 702                             .cloned()
 703                             .filter(|b| !b.is_sized_bound(cx)),
 704                     );
 705
 706                     let proj = projection.map(|p| {
 707                         (
 708                             clean_projection(p.skip_binder().projection_ty, cx, None),
 709                             p.skip_binder().term,
 710                         )
 711                     });
 712                     if let Some(((_, trait_did, name), rhs)) = proj
 713                         .as_ref()
 714                         .and_then(|(lhs, rhs): &(Type, _)| Some((lhs.projection()?, rhs)))
 715                     {
 716                         // FIXME(...): Remove this unwrap()
 717                         impl_trait_proj.entry(param_idx).or_default().push((
 718                             trait_did,
 719                             name,
 720                             rhs.ty().unwrap(),
 721                         ));
 722                     }
 723
 724                     return None;
 725                 }
 726             }
 727
 728             Some(p)
 729         })
 730         .collect::<Vec<_>>();
 731
 732     for (param, mut bounds) in impl_trait {
 733         // Move trait bounds to the front.
 734         bounds.sort_by_key(|b| !matches!(b, GenericBound::TraitBound(..)));
 735
 736         if let crate::core::ImplTraitParam::ParamIndex(idx) = param {
 737             if let Some(proj) = impl_trait_proj.remove(&idx) {
 738                 for (trait_did, name, rhs) in proj {
 739                     let rhs = clean_middle_ty(rhs, cx, None);
 740                     simplify::merge_bounds(cx, &mut bounds, trait_did, name, &Term::Type(rhs));
 741                 }
 742             }
 743         } else {
 744             unreachable!();
 745         }
 746
 747         cx.impl_trait_bounds.insert(param, bounds);
 748     }
 749
 750     // Now that `cx.impl_trait_bounds` is populated, we can process
 751     // remaining predicates which could contain `impl Trait`.
 752     let mut where_predicates =
 753         where_predicates.into_iter().flat_map(|p| clean_predicate(*p, cx)).collect::<Vec<_>>();
 754
 755     // Type parameters have a Sized bound by default unless removed with
 756     // ?Sized. Scan through the predicates and mark any type parameter with
 757     // a Sized bound, removing the bounds as we find them.
 758     //
 759     // Note that associated types also have a sized bound by default, but we
 760     // don't actually know the set of associated types right here so that's
 761     // handled in cleaning associated types
 762     let mut sized_params = FxHashSet::default();
 763     where_predicates.retain(|pred| match *pred {
 764         WherePredicate::BoundPredicate { ty: Generic(ref g), ref bounds, .. } => {
 765             if bounds.iter().any(|b| b.is_sized_bound(cx)) {
 766                 sized_params.insert(*g);
 767                 false
 768             } else {
 769                 true
 770             }
 771         }
 772         _ => true,
 773     });
 774
 775     // Run through the type parameters again and insert a ?Sized
 776     // unbound for any we didn't find to be Sized.
 777     for tp in &stripped_params {
 778         if matches!(tp.kind, types::GenericParamDefKind::Type { .. })
 779             && !sized_params.contains(&tp.name)
 780         {
 781             where_predicates.push(WherePredicate::BoundPredicate {
 782                 ty: Type::Generic(tp.name),
 783                 bounds: vec![GenericBound::maybe_sized(cx)],
 784                 bound_params: Vec::new(),
 785             })
 786         }
 787     }
 788
 789     // It would be nice to collect all of the bounds on a type and recombine
 790     // them if possible, to avoid e.g., `where T: Foo, T: Bar, T: Sized, T: 'a`
 791     // and instead see `where T: Foo + Bar + Sized + 'a`
 792
 793     Generics {
 794         params: stripped_params,
 795         where_predicates: simplify::where_clauses(cx, where_predicates),
 796     }
 797 }
 798
 799 fn clean_fn_or_proc_macro<'tcx>(
 800     item: &hir::Item<'tcx>,
 801     sig: &hir::FnSig<'tcx>,
 802     generics: &hir::Generics<'tcx>,
 803     body_id: hir::BodyId,
 804     name: &mut Symbol,
 805     cx: &mut DocContext<'tcx>,
 806 ) -> ItemKind {
 807     let attrs = cx.tcx.hir().attrs(item.hir_id());
 808     let macro_kind = attrs.iter().find_map(|a| {
 809         if a.has_name(sym::proc_macro) {
 810             Some(MacroKind::Bang)
 811         } else if a.has_name(sym::proc_macro_derive) {
 812             Some(MacroKind::Derive)
 813         } else if a.has_name(sym::proc_macro_attribute) {
 814             Some(MacroKind::Attr)
 815         } else {
 816             None
 817         }
 818     });
 819     match macro_kind {
 820         Some(kind) => {
 821             if kind == MacroKind::Derive {
 822                 *name = attrs
 823                     .lists(sym::proc_macro_derive)
 824                     .find_map(|mi| mi.ident())
 825                     .expect("proc-macro derives require a name")
 826                     .name;
 827             }
 828
 829             let mut helpers = Vec::new();
 830             for mi in attrs.lists(sym::proc_macro_derive) {
 831                 if !mi.has_name(sym::attributes) {
 832                     continue;
 833                 }
 834
 835                 if let Some(list) = mi.meta_item_list() {
 836                     for inner_mi in list {
 837                         if let Some(ident) = inner_mi.ident() {
 838                             helpers.push(ident.name);
 839                         }
 840                     }
 841                 }
 842             }
 843             ProcMacroItem(ProcMacro { kind, helpers })
 844         }
 845         None => {
 846             let mut func = clean_function(cx, sig, generics, body_id);
 847             clean_fn_decl_legacy_const_generics(&mut func, attrs);
 848             FunctionItem(func)
 849         }
 850     }
 851 }
 852
 853 /// This is needed to make it more "readable" when documenting functions using
 854 /// `rustc_legacy_const_generics`. More information in
 855 /// <https://github.com/rust-lang/rust/issues/83167>.
 856 fn clean_fn_decl_legacy_const_generics(func: &mut Function, attrs: &[ast::Attribute]) {
 857     for meta_item_list in attrs
 858         .iter()
 859         .filter(|a| a.has_name(sym::rustc_legacy_const_generics))
 860         .filter_map(|a| a.meta_item_list())
 861     {
 862         for (pos, literal) in meta_item_list.iter().filter_map(|meta| meta.literal()).enumerate() {
 863             match literal.kind {
 864                 ast::LitKind::Int(a, _) => {
 865                     let gen = func.generics.params.remove(0);
 866                     if let GenericParamDef { name, kind: GenericParamDefKind::Const { ty, .. } } =
 867                         gen
 868                     {
 869                         func.decl
 870                             .inputs
 871                             .values
 872                             .insert(a as _, Argument { name, type_: *ty, is_const: true });
 873                     } else {
 874                         panic!("unexpected non const in position {pos}");
 875                     }
 876                 }
 877                 _ => panic!("invalid arg index"),
 878             }
 879         }
 880     }
 881 }
 882
 883 fn clean_function<'tcx>(
 884     cx: &mut DocContext<'tcx>,
 885     sig: &hir::FnSig<'tcx>,
 886     generics: &hir::Generics<'tcx>,
 887     body_id: hir::BodyId,
 888 ) -> Box<Function> {
 889     let (generics, decl) = enter_impl_trait(cx, |cx| {
 890         // NOTE: generics must be cleaned before args
 891         let generics = clean_generics(generics, cx);
 892         let args = clean_args_from_types_and_body_id(cx, sig.decl.inputs, body_id);
 893         let decl = clean_fn_decl_with_args(cx, sig.decl, args);
 894         (generics, decl)
 895     });
 896     Box::new(Function { decl, generics })
 897 }
 898
 899 fn clean_args_from_types_and_names<'tcx>(
 900     cx: &mut DocContext<'tcx>,
 901     types: &[hir::Ty<'tcx>],
 902     names: &[Ident],
 903 ) -> Arguments {
 904     Arguments {
 905         values: types
 906             .iter()
 907             .enumerate()
 908             .map(|(i, ty)| {
 909                 let mut name = names.get(i).map_or(kw::Empty, |ident| ident.name);
 910                 if name.is_empty() {
 911                     name = kw::Underscore;
 912                 }
 913                 Argument { name, type_: clean_ty(ty, cx), is_const: false }
 914             })
 915             .collect(),
 916     }
 917 }
 918
 919 fn clean_args_from_types_and_body_id<'tcx>(
 920     cx: &mut DocContext<'tcx>,
 921     types: &[hir::Ty<'tcx>],
 922     body_id: hir::BodyId,
 923 ) -> Arguments {
 924     let body = cx.tcx.hir().body(body_id);
 925
 926     Arguments {
 927         values: types
 928             .iter()
 929             .enumerate()
 930             .map(|(i, ty)| Argument {
 931                 name: name_from_pat(body.params[i].pat),
 932                 type_: clean_ty(ty, cx),
 933                 is_const: false,
 934             })
 935             .collect(),
 936     }
 937 }
 938
 939 fn clean_fn_decl_with_args<'tcx>(
 940     cx: &mut DocContext<'tcx>,
 941     decl: &hir::FnDecl<'tcx>,
 942     args: Arguments,
 943 ) -> FnDecl {
 944     let output = match decl.output {
 945         hir::FnRetTy::Return(typ) => Return(clean_ty(typ, cx)),
 946         hir::FnRetTy::DefaultReturn(..) => DefaultReturn,
 947     };
 948     FnDecl { inputs: args, output, c_variadic: decl.c_variadic }
 949 }
 950
 951 fn clean_fn_decl_from_did_and_sig<'tcx>(
 952     cx: &mut DocContext<'tcx>,
 953     did: Option<DefId>,
 954     sig: ty::PolyFnSig<'tcx>,
 955 ) -> FnDecl {
 956     let mut names = did.map_or(&[] as &[_], |did| cx.tcx.fn_arg_names(did)).iter();
 957
 958     // We assume all empty tuples are default return type. This theoretically can discard `-> ()`,
 959     // but shouldn't change any code meaning.
 960     let output = match clean_middle_ty(sig.skip_binder().output(), cx, None) {
 961         Type::Tuple(inner) if inner.is_empty() => DefaultReturn,
 962         ty => Return(ty),
 963     };
 964
 965     FnDecl {
 966         output,
 967         c_variadic: sig.skip_binder().c_variadic,
 968         inputs: Arguments {
 969             values: sig
 970                 .skip_binder()
 971                 .inputs()
 972                 .iter()
 973                 .map(|t| Argument {
 974                     type_: clean_middle_ty(*t, cx, None),
 975                     name: names.next().map_or(kw::Empty, |i| i.name),
 976                     is_const: false,
 977                 })
 978                 .collect(),
 979         },
 980     }
 981 }
 982
 983 fn clean_trait_ref<'tcx>(trait_ref: &hir::TraitRef<'tcx>, cx: &mut DocContext<'tcx>) -> Path {
 984     let path = clean_path(trait_ref.path, cx);
 985     register_res(cx, path.res);
 986     path
 987 }
 988
 989 fn clean_poly_trait_ref<'tcx>(
 990     poly_trait_ref: &hir::PolyTraitRef<'tcx>,
 991     cx: &mut DocContext<'tcx>,
 992 ) -> PolyTrait {
 993     PolyTrait {
 994         trait_: clean_trait_ref(&poly_trait_ref.trait_ref, cx),
 995         generic_params: poly_trait_ref
 996             .bound_generic_params
 997             .iter()
 998             .filter(|p| !is_elided_lifetime(p))
 999             .map(|x| clean_generic_param(cx, None, x))
1000             .collect(),
1001     }
1002 }
1003
1004 fn clean_trait_item<'tcx>(trait_item: &hir::TraitItem<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
1005     let local_did = trait_item.def_id.to_def_id();
1006     cx.with_param_env(local_did, |cx| {
1007         let inner = match trait_item.kind {
1008             hir::TraitItemKind::Const(ty, Some(default)) => AssocConstItem(
1009                 clean_ty(ty, cx),
1010                 ConstantKind::Local { def_id: local_did, body: default },
1011             ),
1012             hir::TraitItemKind::Const(ty, None) => TyAssocConstItem(clean_ty(ty, cx)),
1013             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
1014                 let m = clean_function(cx, sig, trait_item.generics, body);
1015                 MethodItem(m, None)
1016             }
1017             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(names)) => {
1018                 let (generics, decl) = enter_impl_trait(cx, |cx| {
1019                     // NOTE: generics must be cleaned before args
1020                     let generics = clean_generics(trait_item.generics, cx);
1021                     let args = clean_args_from_types_and_names(cx, sig.decl.inputs, names);
1022                     let decl = clean_fn_decl_with_args(cx, sig.decl, args);
1023                     (generics, decl)
1024                 });
1025                 TyMethodItem(Box::new(Function { decl, generics }))
1026             }
1027             hir::TraitItemKind::Type(bounds, Some(default)) => {
1028                 let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
1029                 let bounds = bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect();
1030                 let item_type = clean_middle_ty(hir_ty_to_ty(cx.tcx, default), cx, None);
1031                 AssocTypeItem(
1032                     Box::new(Typedef {
1033                         type_: clean_ty(default, cx),
1034                         generics,
1035                         item_type: Some(item_type),
1036                     }),
1037                     bounds,
1038                 )
1039             }
1040             hir::TraitItemKind::Type(bounds, None) => {
1041                 let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
1042                 let bounds = bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect();
1043                 TyAssocTypeItem(Box::new(generics), bounds)
1044             }
1045         };
1046         let what_rustc_thinks =
1047             Item::from_def_id_and_parts(local_did, Some(trait_item.ident.name), inner, cx);
1048         // Trait items always inherit the trait's visibility -- we don't want to show `pub`.
1049         Item { visibility: Inherited, ..what_rustc_thinks }
1050     })
1051 }
1052
1053 pub(crate) fn clean_impl_item<'tcx>(
1054     impl_: &hir::ImplItem<'tcx>,
1055     cx: &mut DocContext<'tcx>,
1056 ) -> Item {
1057     let local_did = impl_.def_id.to_def_id();
1058     cx.with_param_env(local_did, |cx| {
1059         let inner = match impl_.kind {
1060             hir::ImplItemKind::Const(ty, expr) => {
1061                 let default = ConstantKind::Local { def_id: local_did, body: expr };
1062                 AssocConstItem(clean_ty(ty, cx), default)
1063             }
1064             hir::ImplItemKind::Fn(ref sig, body) => {
1065                 let m = clean_function(cx, sig, impl_.generics, body);
1066                 let defaultness = cx.tcx.impl_defaultness(impl_.def_id);
1067                 MethodItem(m, Some(defaultness))
1068             }
1069             hir::ImplItemKind::TyAlias(hir_ty) => {
1070                 let type_ = clean_ty(hir_ty, cx);
1071                 let generics = clean_generics(impl_.generics, cx);
1072                 let item_type = clean_middle_ty(hir_ty_to_ty(cx.tcx, hir_ty), cx, None);
1073                 AssocTypeItem(
1074                     Box::new(Typedef { type_, generics, item_type: Some(item_type) }),
1075                     Vec::new(),
1076                 )
1077             }
1078         };
1079
1080         let mut what_rustc_thinks =
1081             Item::from_def_id_and_parts(local_did, Some(impl_.ident.name), inner, cx);
1082
1083         let impl_ref = cx.tcx.impl_trait_ref(cx.tcx.local_parent(impl_.def_id));
1084
1085         // Trait impl items always inherit the impl's visibility --
1086         // we don't want to show `pub`.
1087         if impl_ref.is_some() {
1088             what_rustc_thinks.visibility = Inherited;
1089         }
1090
1091         what_rustc_thinks
1092     })
1093 }
1094
1095 pub(crate) fn clean_middle_assoc_item<'tcx>(
1096     assoc_item: &ty::AssocItem,
1097     cx: &mut DocContext<'tcx>,
1098 ) -> Item {
1099     let tcx = cx.tcx;
1100     let kind = match assoc_item.kind {
1101         ty::AssocKind::Const => {
1102             let ty = clean_middle_ty(tcx.type_of(assoc_item.def_id), cx, Some(assoc_item.def_id));
1103
1104             let provided = match assoc_item.container {
1105                 ty::ImplContainer => true,
1106                 ty::TraitContainer => tcx.impl_defaultness(assoc_item.def_id).has_value(),
1107             };
1108             if provided {
1109                 AssocConstItem(ty, ConstantKind::Extern { def_id: assoc_item.def_id })
1110             } else {
1111                 TyAssocConstItem(ty)
1112             }
1113         }
1114         ty::AssocKind::Fn => {
1115             let generics = clean_ty_generics(
1116                 cx,
1117                 tcx.generics_of(assoc_item.def_id),
1118                 tcx.explicit_predicates_of(assoc_item.def_id),
1119             );
1120             let sig = tcx.fn_sig(assoc_item.def_id);
1121             let mut decl = clean_fn_decl_from_did_and_sig(cx, Some(assoc_item.def_id), sig);
1122
1123             if assoc_item.fn_has_self_parameter {
1124                 let self_ty = match assoc_item.container {
1125                     ty::ImplContainer => tcx.type_of(assoc_item.container_id(tcx)),
1126                     ty::TraitContainer => tcx.types.self_param,
1127                 };
1128                 let self_arg_ty = sig.input(0).skip_binder();
1129                 if self_arg_ty == self_ty {
1130                     decl.inputs.values[0].type_ = Generic(kw::SelfUpper);
1131                 } else if let ty::Ref(_, ty, _) = *self_arg_ty.kind() {
1132                     if ty == self_ty {
1133                         match decl.inputs.values[0].type_ {
1134                             BorrowedRef { ref mut type_, .. } => **type_ = Generic(kw::SelfUpper),
1135                             _ => unreachable!(),
1136                         }
1137                     }
1138                 }
1139             }
1140
1141             let provided = match assoc_item.container {
1142                 ty::ImplContainer => true,
1143                 ty::TraitContainer => assoc_item.defaultness(tcx).has_value(),
1144             };
1145             if provided {
1146                 let defaultness = match assoc_item.container {
1147                     ty::ImplContainer => Some(assoc_item.defaultness(tcx)),
1148                     ty::TraitContainer => None,
1149                 };
1150                 MethodItem(Box::new(Function { generics, decl }), defaultness)
1151             } else {
1152                 TyMethodItem(Box::new(Function { generics, decl }))
1153             }
1154         }
1155         ty::AssocKind::Type => {
1156             let my_name = assoc_item.name;
1157
1158             fn param_eq_arg(param: &GenericParamDef, arg: &GenericArg) -> bool {
1159                 match (&param.kind, arg) {
1160                     (GenericParamDefKind::Type { .. }, GenericArg::Type(Type::Generic(ty)))
1161                         if *ty == param.name =>
1162                     {
1163                         true
1164                     }
1165                     (GenericParamDefKind::Lifetime { .. }, GenericArg::Lifetime(Lifetime(lt)))
1166                         if *lt == param.name =>
1167                     {
1168                         true
1169                     }
1170                     (GenericParamDefKind::Const { .. }, GenericArg::Const(c)) => match &c.kind {
1171                         ConstantKind::TyConst { expr } => expr == param.name.as_str(),
1172                         _ => false,
1173                     },
1174                     _ => false,
1175                 }
1176             }
1177
1178             if let ty::TraitContainer = assoc_item.container {
1179                 let bounds = tcx.explicit_item_bounds(assoc_item.def_id);
1180                 let predicates = ty::GenericPredicates { parent: None, predicates: bounds };
1181                 let mut generics =
1182                     clean_ty_generics(cx, tcx.generics_of(assoc_item.def_id), predicates);
1183                 // Filter out the bounds that are (likely?) directly attached to the associated type,
1184                 // as opposed to being located in the where clause.
1185                 let mut bounds = generics
1186                     .where_predicates
1187                     .drain_filter(|pred| match *pred {
1188                         WherePredicate::BoundPredicate {
1189                             ty: QPath { ref assoc, ref self_type, ref trait_, .. },
1190                             ..
1191                         } => {
1192                             if assoc.name != my_name {
1193                                 return false;
1194                             }
1195                             if trait_.def_id() != assoc_item.container_id(tcx) {
1196                                 return false;
1197                             }
1198                             match **self_type {
1199                                 Generic(ref s) if *s == kw::SelfUpper => {}
1200                                 _ => return false,
1201                             }
1202                             match &assoc.args {
1203                                 GenericArgs::AngleBracketed { args, bindings } => {
1204                                     if !bindings.is_empty()
1205                                         || generics
1206                                             .params
1207                                             .iter()
1208                                             .zip(args.iter())
1209                                             .any(|(param, arg)| !param_eq_arg(param, arg))
1210                                     {
1211                                         return false;
1212                                     }
1213                                 }
1214                                 GenericArgs::Parenthesized { .. } => {
1215                                     // The only time this happens is if we're inside the rustdoc for Fn(),
1216                                     // which only has one associated type, which is not a GAT, so whatever.
1217                                 }
1218                             }
1219                             true
1220                         }
1221                         _ => false,
1222                     })
1223                     .flat_map(|pred| {
1224                         if let WherePredicate::BoundPredicate { bounds, .. } = pred {
1225                             bounds
1226                         } else {
1227                             unreachable!()
1228                         }
1229                     })
1230                     .collect::<Vec<_>>();
1231                 // Our Sized/?Sized bound didn't get handled when creating the generics
1232                 // because we didn't actually get our whole set of bounds until just now
1233                 // (some of them may have come from the trait). If we do have a sized
1234                 // bound, we remove it, and if we don't then we add the `?Sized` bound
1235                 // at the end.
1236                 match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1237                     Some(i) => {
1238                         bounds.remove(i);
1239                     }
1240                     None => bounds.push(GenericBound::maybe_sized(cx)),
1241                 }
1242
1243                 if tcx.impl_defaultness(assoc_item.def_id).has_value() {
1244                     AssocTypeItem(
1245                         Box::new(Typedef {
1246                             type_: clean_middle_ty(
1247                                 tcx.type_of(assoc_item.def_id),
1248                                 cx,
1249                                 Some(assoc_item.def_id),
1250                             ),
1251                             generics,
1252                             // FIXME: should we obtain the Type from HIR and pass it on here?
1253                             item_type: None,
1254                         }),
1255                         bounds,
1256                     )
1257                 } else {
1258                     TyAssocTypeItem(Box::new(generics), bounds)
1259                 }
1260             } else {
1261                 // FIXME: when could this happen? Associated items in inherent impls?
1262                 AssocTypeItem(
1263                     Box::new(Typedef {
1264                         type_: clean_middle_ty(
1265                             tcx.type_of(assoc_item.def_id),
1266                             cx,
1267                             Some(assoc_item.def_id),
1268                         ),
1269                         generics: Generics { params: Vec::new(), where_predicates: Vec::new() },
1270                         item_type: None,
1271                     }),
1272                     Vec::new(),
1273                 )
1274             }
1275         }
1276     };
1277
1278     let mut what_rustc_thinks =
1279         Item::from_def_id_and_parts(assoc_item.def_id, Some(assoc_item.name), kind, cx);
1280
1281     let impl_ref = tcx.impl_trait_ref(tcx.parent(assoc_item.def_id));
1282
1283     // Trait impl items always inherit the impl's visibility --
1284     // we don't want to show `pub`.
1285     if impl_ref.is_some() {
1286         what_rustc_thinks.visibility = Visibility::Inherited;
1287     }
1288
1289     what_rustc_thinks
1290 }
1291
1292 fn clean_qpath<'tcx>(hir_ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1293     let hir::Ty { hir_id: _, span, ref kind } = *hir_ty;
1294     let hir::TyKind::Path(qpath) = kind else { unreachable!() };
1295
1296     match qpath {
1297         hir::QPath::Resolved(None, path) => {
1298             if let Res::Def(DefKind::TyParam, did) = path.res {
1299                 if let Some(new_ty) = cx.substs.get(&did).and_then(|p| p.as_ty()).cloned() {
1300                     return new_ty;
1301                 }
1302                 if let Some(bounds) = cx.impl_trait_bounds.remove(&did.into()) {
1303                     return ImplTrait(bounds);
1304                 }
1305             }
1306
1307             if let Some(expanded) = maybe_expand_private_type_alias(cx, path) {
1308                 expanded
1309             } else {
1310                 let path = clean_path(path, cx);
1311                 resolve_type(cx, path)
1312             }
1313         }
1314         hir::QPath::Resolved(Some(qself), p) => {
1315             // Try to normalize `<X as Y>::T` to a type
1316             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1317             if let Some(normalized_value) = normalize(cx, ty) {
1318                 return clean_middle_ty(normalized_value, cx, None);
1319             }
1320
1321             let trait_segments = &p.segments[..p.segments.len() - 1];
1322             let trait_def = cx.tcx.associated_item(p.res.def_id()).container_id(cx.tcx);
1323             let trait_ = self::Path {
1324                 res: Res::Def(DefKind::Trait, trait_def),
1325                 segments: trait_segments.iter().map(|x| x.clean(cx)).collect(),
1326             };
1327             register_res(cx, trait_.res);
1328             let self_def_id = DefId::local(qself.hir_id.owner.local_def_index);
1329             let self_type = clean_ty(qself, cx);
1330             let should_show_cast = compute_should_show_cast(Some(self_def_id), &trait_, &self_type);
1331             Type::QPath {
1332                 assoc: Box::new(p.segments.last().expect("segments were empty").clean(cx)),
1333                 should_show_cast,
1334                 self_type: Box::new(self_type),
1335                 trait_,
1336             }
1337         }
1338         hir::QPath::TypeRelative(qself, segment) => {
1339             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1340             let res = match ty.kind() {
1341                 ty::Projection(proj) => Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id),
1342                 // Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
1343                 ty::Error(_) => return Type::Infer,
1344                 _ => bug!("clean: expected associated type, found `{:?}`", ty),
1345             };
1346             let trait_ = clean_path(&hir::Path { span, res, segments: &[] }, cx);
1347             register_res(cx, trait_.res);
1348             let self_def_id = res.opt_def_id();
1349             let self_type = clean_ty(qself, cx);
1350             let should_show_cast = compute_should_show_cast(self_def_id, &trait_, &self_type);
1351             Type::QPath {
1352                 assoc: Box::new(segment.clean(cx)),
1353                 should_show_cast,
1354                 self_type: Box::new(self_type),
1355                 trait_,
1356             }
1357         }
1358         hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1359     }
1360 }
1361
1362 fn maybe_expand_private_type_alias<'tcx>(
1363     cx: &mut DocContext<'tcx>,
1364     path: &hir::Path<'tcx>,
1365 ) -> Option<Type> {
1366     let Res::Def(DefKind::TyAlias, def_id) = path.res else { return None };
1367     // Substitute private type aliases
1368     let def_id = def_id.as_local()?;
1369     let alias = if !cx.cache.access_levels.is_exported(def_id.to_def_id()) {
1370         &cx.tcx.hir().expect_item(def_id).kind
1371     } else {
1372         return None;
1373     };
1374     let hir::ItemKind::TyAlias(ty, generics) = alias else { return None };
1375
1376     let provided_params = &path.segments.last().expect("segments were empty");
1377     let mut substs = FxHashMap::default();
1378     let generic_args = provided_params.args();
1379
1380     let mut indices: hir::GenericParamCount = Default::default();
1381     for param in generics.params.iter() {
1382         match param.kind {
1383             hir::GenericParamKind::Lifetime { .. } => {
1384                 let mut j = 0;
1385                 let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1386                     hir::GenericArg::Lifetime(lt) => {
1387                         if indices.lifetimes == j {
1388                             return Some(lt);
1389                         }
1390                         j += 1;
1391                         None
1392                     }
1393                     _ => None,
1394                 });
1395                 if let Some(lt) = lifetime.cloned() {
1396                     let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1397                     let cleaned =
1398                         if !lt.is_elided() { clean_lifetime(lt, cx) } else { Lifetime::elided() };
1399                     substs.insert(lt_def_id.to_def_id(), SubstParam::Lifetime(cleaned));
1400                 }
1401                 indices.lifetimes += 1;
1402             }
1403             hir::GenericParamKind::Type { ref default, .. } => {
1404                 let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1405                 let mut j = 0;
1406                 let type_ = generic_args.args.iter().find_map(|arg| match arg {
1407                     hir::GenericArg::Type(ty) => {
1408                         if indices.types == j {
1409                             return Some(ty);
1410                         }
1411                         j += 1;
1412                         None
1413                     }
1414                     _ => None,
1415                 });
1416                 if let Some(ty) = type_ {
1417                     substs.insert(ty_param_def_id.to_def_id(), SubstParam::Type(clean_ty(ty, cx)));
1418                 } else if let Some(default) = *default {
1419                     substs.insert(
1420                         ty_param_def_id.to_def_id(),
1421                         SubstParam::Type(clean_ty(default, cx)),
1422                     );
1423                 }
1424                 indices.types += 1;
1425             }
1426             hir::GenericParamKind::Const { .. } => {
1427                 let const_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1428                 let mut j = 0;
1429                 let const_ = generic_args.args.iter().find_map(|arg| match arg {
1430                     hir::GenericArg::Const(ct) => {
1431                         if indices.consts == j {
1432                             return Some(ct);
1433                         }
1434                         j += 1;
1435                         None
1436                     }
1437                     _ => None,
1438                 });
1439                 if let Some(ct) = const_ {
1440                     substs.insert(
1441                         const_param_def_id.to_def_id(),
1442                         SubstParam::Constant(clean_const(ct, cx)),
1443                     );
1444                 }
1445                 // FIXME(const_generics_defaults)
1446                 indices.consts += 1;
1447             }
1448         }
1449     }
1450
1451     Some(cx.enter_alias(substs, |cx| clean_ty(ty, cx)))
1452 }
1453
1454 pub(crate) fn clean_ty<'tcx>(ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1455     use rustc_hir::*;
1456
1457     match ty.kind {
1458         TyKind::Never => Primitive(PrimitiveType::Never),
1459         TyKind::Ptr(ref m) => RawPointer(m.mutbl, Box::new(clean_ty(m.ty, cx))),
1460         TyKind::Rptr(ref l, ref m) => {
1461             // There are two times a `Fresh` lifetime can be created:
1462             // 1. For `&'_ x`, written by the user. This corresponds to `lower_lifetime` in `rustc_ast_lowering`.
1463             // 2. For `&x` as a parameter to an `async fn`. This corresponds to `elided_ref_lifetime in `rustc_ast_lowering`.
1464             //    See #59286 for more information.
1465             // Ideally we would only hide the `'_` for case 2., but I don't know a way to distinguish it.
1466             // Turning `fn f(&'_ self)` into `fn f(&self)` isn't the worst thing in the world, though;
1467             // there's no case where it could cause the function to fail to compile.
1468             let elided =
1469                 l.is_elided() || matches!(l.name, LifetimeName::Param(_, ParamName::Fresh));
1470             let lifetime = if elided { None } else { Some(clean_lifetime(*l, cx)) };
1471             BorrowedRef { lifetime, mutability: m.mutbl, type_: Box::new(clean_ty(m.ty, cx)) }
1472         }
1473         TyKind::Slice(ty) => Slice(Box::new(clean_ty(ty, cx))),
1474         TyKind::Array(ty, ref length) => {
1475             let length = match length {
1476                 hir::ArrayLen::Infer(_, _) => "_".to_string(),
1477                 hir::ArrayLen::Body(anon_const) => {
1478                     let def_id = cx.tcx.hir().local_def_id(anon_const.hir_id);
1479                     // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1480                     // as we currently do not supply the parent generics to anonymous constants
1481                     // but do allow `ConstKind::Param`.
1482                     //
1483                     // `const_eval_poly` tries to to first substitute generic parameters which
1484                     // results in an ICE while manually constructing the constant and using `eval`
1485                     // does nothing for `ConstKind::Param`.
1486                     let ct = ty::Const::from_anon_const(cx.tcx, def_id);
1487                     let param_env = cx.tcx.param_env(def_id);
1488                     print_const(cx, ct.eval(cx.tcx, param_env))
1489                 }
1490             };
1491
1492             Array(Box::new(clean_ty(ty, cx)), length)
1493         }
1494         TyKind::Tup(tys) => Tuple(tys.iter().map(|ty| clean_ty(ty, cx)).collect()),
1495         TyKind::OpaqueDef(item_id, _) => {
1496             let item = cx.tcx.hir().item(item_id);
1497             if let hir::ItemKind::OpaqueTy(ref ty) = item.kind {
1498                 ImplTrait(ty.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect())
1499             } else {
1500                 unreachable!()
1501             }
1502         }
1503         TyKind::Path(_) => clean_qpath(ty, cx),
1504         TyKind::TraitObject(bounds, ref lifetime, _) => {
1505             let bounds = bounds.iter().map(|bound| clean_poly_trait_ref(bound, cx)).collect();
1506             let lifetime =
1507                 if !lifetime.is_elided() { Some(clean_lifetime(*lifetime, cx)) } else { None };
1508             DynTrait(bounds, lifetime)
1509         }
1510         TyKind::BareFn(barefn) => BareFunction(Box::new(barefn.clean(cx))),
1511         // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
1512         TyKind::Infer | TyKind::Err => Infer,
1513         TyKind::Typeof(..) => panic!("unimplemented type {:?}", ty.kind),
1514     }
1515 }
1516
1517 /// Returns `None` if the type could not be normalized
1518 fn normalize<'tcx>(cx: &mut DocContext<'tcx>, ty: Ty<'_>) -> Option<Ty<'tcx>> {
1519     // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1520     if !cx.tcx.sess.opts.unstable_opts.normalize_docs {
1521         return None;
1522     }
1523
1524     use crate::rustc_trait_selection::infer::TyCtxtInferExt;
1525     use crate::rustc_trait_selection::traits::query::normalize::AtExt;
1526     use rustc_middle::traits::ObligationCause;
1527
1528     // Try to normalize `<X as Y>::T` to a type
1529     let lifted = ty.lift_to_tcx(cx.tcx).unwrap();
1530     let normalized = cx.tcx.infer_ctxt().enter(|infcx| {
1531         infcx
1532             .at(&ObligationCause::dummy(), cx.param_env)
1533             .normalize(lifted)
1534             .map(|resolved| infcx.resolve_vars_if_possible(resolved.value))
1535     });
1536     match normalized {
1537         Ok(normalized_value) => {
1538             debug!("normalized {:?} to {:?}", ty, normalized_value);
1539             Some(normalized_value)
1540         }
1541         Err(err) => {
1542             debug!("failed to normalize {:?}: {:?}", ty, err);
1543             None
1544         }
1545     }
1546 }
1547
1548 pub(crate) fn clean_middle_ty<'tcx>(
1549     this: Ty<'tcx>,
1550     cx: &mut DocContext<'tcx>,
1551     def_id: Option<DefId>,
1552 ) -> Type {
1553     trace!("cleaning type: {:?}", this);
1554     let ty = normalize(cx, this).unwrap_or(this);
1555     match *ty.kind() {
1556         ty::Never => Primitive(PrimitiveType::Never),
1557         ty::Bool => Primitive(PrimitiveType::Bool),
1558         ty::Char => Primitive(PrimitiveType::Char),
1559         ty::Int(int_ty) => Primitive(int_ty.into()),
1560         ty::Uint(uint_ty) => Primitive(uint_ty.into()),
1561         ty::Float(float_ty) => Primitive(float_ty.into()),
1562         ty::Str => Primitive(PrimitiveType::Str),
1563         ty::Slice(ty) => Slice(Box::new(clean_middle_ty(ty, cx, None))),
1564         ty::Array(ty, n) => {
1565             let mut n = cx.tcx.lift(n).expect("array lift failed");
1566             n = n.eval(cx.tcx, ty::ParamEnv::reveal_all());
1567             let n = print_const(cx, n);
1568             Array(Box::new(clean_middle_ty(ty, cx, None)), n)
1569         }
1570         ty::RawPtr(mt) => RawPointer(mt.mutbl, Box::new(clean_middle_ty(mt.ty, cx, None))),
1571         ty::Ref(r, ty, mutbl) => BorrowedRef {
1572             lifetime: clean_middle_region(r),
1573             mutability: mutbl,
1574             type_: Box::new(clean_middle_ty(ty, cx, None)),
1575         },
1576         ty::FnDef(..) | ty::FnPtr(_) => {
1577             let ty = cx.tcx.lift(this).expect("FnPtr lift failed");
1578             let sig = ty.fn_sig(cx.tcx);
1579             let decl = clean_fn_decl_from_did_and_sig(cx, None, sig);
1580             BareFunction(Box::new(BareFunctionDecl {
1581                 unsafety: sig.unsafety(),
1582                 generic_params: Vec::new(),
1583                 decl,
1584                 abi: sig.abi(),
1585             }))
1586         }
1587         ty::Adt(def, substs) => {
1588             let did = def.did();
1589             let kind = match def.adt_kind() {
1590                 AdtKind::Struct => ItemType::Struct,
1591                 AdtKind::Union => ItemType::Union,
1592                 AdtKind::Enum => ItemType::Enum,
1593             };
1594             inline::record_extern_fqn(cx, did, kind);
1595             let path = external_path(cx, did, false, vec![], substs);
1596             Type::Path { path }
1597         }
1598         ty::Foreign(did) => {
1599             inline::record_extern_fqn(cx, did, ItemType::ForeignType);
1600             let path = external_path(cx, did, false, vec![], InternalSubsts::empty());
1601             Type::Path { path }
1602         }
1603         ty::Dynamic(obj, ref reg) => {
1604             // HACK: pick the first `did` as the `did` of the trait object. Someone
1605             // might want to implement "native" support for marker-trait-only
1606             // trait objects.
1607             let mut dids = obj.auto_traits();
1608             let did = obj
1609                 .principal_def_id()
1610                 .or_else(|| dids.next())
1611                 .unwrap_or_else(|| panic!("found trait object `{:?}` with no traits?", this));
1612             let substs = match obj.principal() {
1613                 Some(principal) => principal.skip_binder().substs,
1614                 // marker traits have no substs.
1615                 _ => cx.tcx.intern_substs(&[]),
1616             };
1617
1618             inline::record_extern_fqn(cx, did, ItemType::Trait);
1619
1620             let lifetime = clean_middle_region(*reg);
1621             let mut bounds = dids
1622                 .map(|did| {
1623                     let empty = cx.tcx.intern_substs(&[]);
1624                     let path = external_path(cx, did, false, vec![], empty);
1625                     inline::record_extern_fqn(cx, did, ItemType::Trait);
1626                     PolyTrait { trait_: path, generic_params: Vec::new() }
1627                 })
1628                 .collect::<Vec<_>>();
1629
1630             let bindings = obj
1631                 .projection_bounds()
1632                 .map(|pb| TypeBinding {
1633                     assoc: projection_to_path_segment(
1634                         pb.skip_binder()
1635                             .lift_to_tcx(cx.tcx)
1636                             .unwrap()
1637                             // HACK(compiler-errors): Doesn't actually matter what self
1638                             // type we put here, because we're only using the GAT's substs.
1639                             .with_self_ty(cx.tcx, cx.tcx.types.self_param)
1640                             .projection_ty,
1641                         cx,
1642                     ),
1643                     kind: TypeBindingKind::Equality {
1644                         term: clean_middle_term(pb.skip_binder().term, cx),
1645                     },
1646                 })
1647                 .collect();
1648
1649             let path = external_path(cx, did, false, bindings, substs);
1650             bounds.insert(0, PolyTrait { trait_: path, generic_params: Vec::new() });
1651
1652             DynTrait(bounds, lifetime)
1653         }
1654         ty::Tuple(t) => Tuple(t.iter().map(|t| clean_middle_ty(t, cx, None)).collect()),
1655
1656         ty::Projection(ref data) => clean_projection(*data, cx, def_id),
1657
1658         ty::Param(ref p) => {
1659             if let Some(bounds) = cx.impl_trait_bounds.remove(&p.index.into()) {
1660                 ImplTrait(bounds)
1661             } else {
1662                 Generic(p.name)
1663             }
1664         }
1665
1666         ty::Opaque(def_id, substs) => {
1667             // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1668             // by looking up the bounds associated with the def_id.
1669             let substs = cx.tcx.lift(substs).expect("Opaque lift failed");
1670             let bounds = cx
1671                 .tcx
1672                 .explicit_item_bounds(def_id)
1673                 .iter()
1674                 .map(|(bound, _)| EarlyBinder(*bound).subst(cx.tcx, substs))
1675                 .collect::<Vec<_>>();
1676             let mut regions = vec![];
1677             let mut has_sized = false;
1678             let mut bounds = bounds
1679                 .iter()
1680                 .filter_map(|bound| {
1681                     let bound_predicate = bound.kind();
1682                     let trait_ref = match bound_predicate.skip_binder() {
1683                         ty::PredicateKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
1684                         ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
1685                             if let Some(r) = clean_middle_region(reg) {
1686                                 regions.push(GenericBound::Outlives(r));
1687                             }
1688                             return None;
1689                         }
1690                         _ => return None,
1691                     };
1692
1693                     if let Some(sized) = cx.tcx.lang_items().sized_trait() {
1694                         if trait_ref.def_id() == sized {
1695                             has_sized = true;
1696                             return None;
1697                         }
1698                     }
1699
1700                     let bindings: Vec<_> = bounds
1701                         .iter()
1702                         .filter_map(|bound| {
1703                             if let ty::PredicateKind::Projection(proj) = bound.kind().skip_binder()
1704                             {
1705                                 if proj.projection_ty.trait_ref(cx.tcx) == trait_ref.skip_binder() {
1706                                     Some(TypeBinding {
1707                                         assoc: projection_to_path_segment(proj.projection_ty, cx),
1708                                         kind: TypeBindingKind::Equality {
1709                                             term: clean_middle_term(proj.term, cx),
1710                                         },
1711                                     })
1712                                 } else {
1713                                     None
1714                                 }
1715                             } else {
1716                                 None
1717                             }
1718                         })
1719                         .collect();
1720
1721                     Some(clean_poly_trait_ref_with_bindings(cx, trait_ref, &bindings))
1722                 })
1723                 .collect::<Vec<_>>();
1724             bounds.extend(regions);
1725             if !has_sized && !bounds.is_empty() {
1726                 bounds.insert(0, GenericBound::maybe_sized(cx));
1727             }
1728             ImplTrait(bounds)
1729         }
1730
1731         ty::Closure(..) => panic!("Closure"),
1732         ty::Generator(..) => panic!("Generator"),
1733         ty::Bound(..) => panic!("Bound"),
1734         ty::Placeholder(..) => panic!("Placeholder"),
1735         ty::GeneratorWitness(..) => panic!("GeneratorWitness"),
1736         ty::Infer(..) => panic!("Infer"),
1737         ty::Error(_) => panic!("Error"),
1738     }
1739 }
1740
1741 pub(crate) fn clean_field<'tcx>(field: &hir::FieldDef<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
1742     let def_id = cx.tcx.hir().local_def_id(field.hir_id).to_def_id();
1743     clean_field_with_def_id(def_id, field.ident.name, clean_ty(field.ty, cx), cx)
1744 }
1745
1746 pub(crate) fn clean_middle_field<'tcx>(field: &ty::FieldDef, cx: &mut DocContext<'tcx>) -> Item {
1747     clean_field_with_def_id(
1748         field.did,
1749         field.name,
1750         clean_middle_ty(cx.tcx.type_of(field.did), cx, Some(field.did)),
1751         cx,
1752     )
1753 }
1754
1755 pub(crate) fn clean_field_with_def_id(
1756     def_id: DefId,
1757     name: Symbol,
1758     ty: Type,
1759     cx: &mut DocContext<'_>,
1760 ) -> Item {
1761     let what_rustc_thinks =
1762         Item::from_def_id_and_parts(def_id, Some(name), StructFieldItem(ty), cx);
1763     if is_field_vis_inherited(cx.tcx, def_id) {
1764         // Variant fields inherit their enum's visibility.
1765         Item { visibility: Visibility::Inherited, ..what_rustc_thinks }
1766     } else {
1767         what_rustc_thinks
1768     }
1769 }
1770
1771 fn is_field_vis_inherited(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
1772     let parent = tcx.parent(def_id);
1773     match tcx.def_kind(parent) {
1774         DefKind::Struct | DefKind::Union => false,
1775         DefKind::Variant => true,
1776         parent_kind => panic!("unexpected parent kind: {:?}", parent_kind),
1777     }
1778 }
1779
1780 pub(crate) fn clean_visibility(vis: ty::Visibility) -> Visibility {
1781     match vis {
1782         ty::Visibility::Public => Visibility::Public,
1783         // NOTE: this is not quite right: `ty` uses `Invisible` to mean 'private',
1784         // while rustdoc really does mean inherited. That means that for enum variants, such as
1785         // `pub enum E { V }`, `V` will be marked as `Public` by `ty`, but as `Inherited` by rustdoc.
1786         // Various parts of clean override `tcx.visibility` explicitly to make sure this distinction is captured.
1787         ty::Visibility::Invisible => Visibility::Inherited,
1788         ty::Visibility::Restricted(module) => Visibility::Restricted(module),
1789     }
1790 }
1791
1792 pub(crate) fn clean_variant_def<'tcx>(variant: &ty::VariantDef, cx: &mut DocContext<'tcx>) -> Item {
1793     let kind = match variant.ctor_kind {
1794         CtorKind::Const => Variant::CLike,
1795         CtorKind::Fn => Variant::Tuple(
1796             variant.fields.iter().map(|field| clean_middle_field(field, cx)).collect(),
1797         ),
1798         CtorKind::Fictive => Variant::Struct(VariantStruct {
1799             struct_type: CtorKind::Fictive,
1800             fields: variant.fields.iter().map(|field| clean_middle_field(field, cx)).collect(),
1801         }),
1802     };
1803     let what_rustc_thinks =
1804         Item::from_def_id_and_parts(variant.def_id, Some(variant.name), VariantItem(kind), cx);
1805     // don't show `pub` for variants, which always inherit visibility
1806     Item { visibility: Inherited, ..what_rustc_thinks }
1807 }
1808
1809 fn clean_variant_data<'tcx>(
1810     variant: &hir::VariantData<'tcx>,
1811     cx: &mut DocContext<'tcx>,
1812 ) -> Variant {
1813     match variant {
1814         hir::VariantData::Struct(..) => Variant::Struct(VariantStruct {
1815             struct_type: CtorKind::from_hir(variant),
1816             fields: variant.fields().iter().map(|x| clean_field(x, cx)).collect(),
1817         }),
1818         hir::VariantData::Tuple(..) => {
1819             Variant::Tuple(variant.fields().iter().map(|x| clean_field(x, cx)).collect())
1820         }
1821         hir::VariantData::Unit(..) => Variant::CLike,
1822     }
1823 }
1824
1825 fn clean_path<'tcx>(path: &hir::Path<'tcx>, cx: &mut DocContext<'tcx>) -> Path {
1826     Path { res: path.res, segments: path.segments.iter().map(|x| x.clean(cx)).collect() }
1827 }
1828
1829 fn clean_generic_args<'tcx>(
1830     generic_args: &hir::GenericArgs<'tcx>,
1831     cx: &mut DocContext<'tcx>,
1832 ) -> GenericArgs {
1833     if generic_args.parenthesized {
1834         let output = clean_ty(generic_args.bindings[0].ty(), cx);
1835         let output = if output != Type::Tuple(Vec::new()) { Some(Box::new(output)) } else { None };
1836         let inputs =
1837             generic_args.inputs().iter().map(|x| clean_ty(x, cx)).collect::<Vec<_>>().into();
1838         GenericArgs::Parenthesized { inputs, output }
1839     } else {
1840         let args = generic_args
1841             .args
1842             .iter()
1843             .map(|arg| match arg {
1844                 hir::GenericArg::Lifetime(lt) if !lt.is_elided() => {
1845                     GenericArg::Lifetime(clean_lifetime(*lt, cx))
1846                 }
1847                 hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
1848                 hir::GenericArg::Type(ty) => GenericArg::Type(clean_ty(ty, cx)),
1849                 hir::GenericArg::Const(ct) => GenericArg::Const(Box::new(clean_const(ct, cx))),
1850                 hir::GenericArg::Infer(_inf) => GenericArg::Infer,
1851             })
1852             .collect::<Vec<_>>()
1853             .into();
1854         let bindings = generic_args
1855             .bindings
1856             .iter()
1857             .map(|x| clean_type_binding(x, cx))
1858             .collect::<Vec<_>>()
1859             .into();
1860         GenericArgs::AngleBracketed { args, bindings }
1861     }
1862 }
1863
1864 impl<'tcx> Clean<'tcx, PathSegment> for hir::PathSegment<'tcx> {
1865     fn clean(&self, cx: &mut DocContext<'tcx>) -> PathSegment {
1866         PathSegment { name: self.ident.name, args: clean_generic_args(self.args(), cx) }
1867     }
1868 }
1869
1870 impl<'tcx> Clean<'tcx, BareFunctionDecl> for hir::BareFnTy<'tcx> {
1871     fn clean(&self, cx: &mut DocContext<'tcx>) -> BareFunctionDecl {
1872         let (generic_params, decl) = enter_impl_trait(cx, |cx| {
1873             // NOTE: generics must be cleaned before args
1874             let generic_params = self
1875                 .generic_params
1876                 .iter()
1877                 .filter(|p| !is_elided_lifetime(p))
1878                 .map(|x| clean_generic_param(cx, None, x))
1879                 .collect();
1880             let args = clean_args_from_types_and_names(cx, self.decl.inputs, self.param_names);
1881             let decl = clean_fn_decl_with_args(cx, self.decl, args);
1882             (generic_params, decl)
1883         });
1884         BareFunctionDecl { unsafety: self.unsafety, abi: self.abi, decl, generic_params }
1885     }
1886 }
1887
1888 fn clean_maybe_renamed_item<'tcx>(
1889     cx: &mut DocContext<'tcx>,
1890     item: &hir::Item<'tcx>,
1891     renamed: Option<Symbol>,
1892 ) -> Vec<Item> {
1893     use hir::ItemKind;
1894
1895     let def_id = item.def_id.to_def_id();
1896     let mut name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
1897     cx.with_param_env(def_id, |cx| {
1898         let kind = match item.kind {
1899             ItemKind::Static(ty, mutability, body_id) => {
1900                 StaticItem(Static { type_: clean_ty(ty, cx), mutability, expr: Some(body_id) })
1901             }
1902             ItemKind::Const(ty, body_id) => ConstantItem(Constant {
1903                 type_: clean_ty(ty, cx),
1904                 kind: ConstantKind::Local { body: body_id, def_id },
1905             }),
1906             ItemKind::OpaqueTy(ref ty) => OpaqueTyItem(OpaqueTy {
1907                 bounds: ty.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
1908                 generics: clean_generics(ty.generics, cx),
1909             }),
1910             ItemKind::TyAlias(hir_ty, generics) => {
1911                 let rustdoc_ty = clean_ty(hir_ty, cx);
1912                 let ty = clean_middle_ty(hir_ty_to_ty(cx.tcx, hir_ty), cx, None);
1913                 TypedefItem(Box::new(Typedef {
1914                     type_: rustdoc_ty,
1915                     generics: clean_generics(generics, cx),
1916                     item_type: Some(ty),
1917                 }))
1918             }
1919             ItemKind::Enum(ref def, generics) => EnumItem(Enum {
1920                 variants: def.variants.iter().map(|v| v.clean(cx)).collect(),
1921                 generics: clean_generics(generics, cx),
1922             }),
1923             ItemKind::TraitAlias(generics, bounds) => TraitAliasItem(TraitAlias {
1924                 generics: clean_generics(generics, cx),
1925                 bounds: bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
1926             }),
1927             ItemKind::Union(ref variant_data, generics) => UnionItem(Union {
1928                 generics: clean_generics(generics, cx),
1929                 fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
1930             }),
1931             ItemKind::Struct(ref variant_data, generics) => StructItem(Struct {
1932                 struct_type: CtorKind::from_hir(variant_data),
1933                 generics: clean_generics(generics, cx),
1934                 fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
1935             }),
1936             ItemKind::Impl(impl_) => return clean_impl(impl_, item.hir_id(), cx),
1937             // proc macros can have a name set by attributes
1938             ItemKind::Fn(ref sig, generics, body_id) => {
1939                 clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
1940             }
1941             ItemKind::Macro(ref macro_def, _) => {
1942                 let ty_vis = clean_visibility(cx.tcx.visibility(def_id));
1943                 MacroItem(Macro {
1944                     source: display_macro_source(cx, name, macro_def, def_id, ty_vis),
1945                 })
1946             }
1947             ItemKind::Trait(_, _, generics, bounds, item_ids) => {
1948                 let items = item_ids
1949                     .iter()
1950                     .map(|ti| clean_trait_item(cx.tcx.hir().trait_item(ti.id), cx))
1951                     .collect();
1952
1953                 TraitItem(Trait {
1954                     def_id,
1955                     items,
1956                     generics: clean_generics(generics, cx),
1957                     bounds: bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
1958                 })
1959             }
1960             ItemKind::ExternCrate(orig_name) => {
1961                 return clean_extern_crate(item, name, orig_name, cx);
1962             }
1963             ItemKind::Use(path, kind) => {
1964                 return clean_use_statement(item, name, path, kind, cx, &mut FxHashSet::default());
1965             }
1966             _ => unreachable!("not yet converted"),
1967         };
1968
1969         vec![Item::from_def_id_and_parts(def_id, Some(name), kind, cx)]
1970     })
1971 }
1972
1973 impl<'tcx> Clean<'tcx, Item> for hir::Variant<'tcx> {
1974     fn clean(&self, cx: &mut DocContext<'tcx>) -> Item {
1975         let kind = VariantItem(clean_variant_data(&self.data, cx));
1976         let what_rustc_thinks =
1977             Item::from_hir_id_and_parts(self.id, Some(self.ident.name), kind, cx);
1978         // don't show `pub` for variants, which are always public
1979         Item { visibility: Inherited, ..what_rustc_thinks }
1980     }
1981 }
1982
1983 fn clean_impl<'tcx>(
1984     impl_: &hir::Impl<'tcx>,
1985     hir_id: hir::HirId,
1986     cx: &mut DocContext<'tcx>,
1987 ) -> Vec<Item> {
1988     let tcx = cx.tcx;
1989     let mut ret = Vec::new();
1990     let trait_ = impl_.of_trait.as_ref().map(|t| clean_trait_ref(t, cx));
1991     let items = impl_
1992         .items
1993         .iter()
1994         .map(|ii| clean_impl_item(tcx.hir().impl_item(ii.id), cx))
1995         .collect::<Vec<_>>();
1996     let def_id = tcx.hir().local_def_id(hir_id);
1997
1998     // If this impl block is an implementation of the Deref trait, then we
1999     // need to try inlining the target's inherent impl blocks as well.
2000     if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
2001         build_deref_target_impls(cx, &items, &mut ret);
2002     }
2003
2004     let for_ = clean_ty(impl_.self_ty, cx);
2005     let type_alias = for_.def_id(&cx.cache).and_then(|did| match tcx.def_kind(did) {
2006         DefKind::TyAlias => Some(clean_middle_ty(tcx.type_of(did), cx, Some(did))),
2007         _ => None,
2008     });
2009     let mut make_item = |trait_: Option<Path>, for_: Type, items: Vec<Item>| {
2010         let kind = ImplItem(Box::new(Impl {
2011             unsafety: impl_.unsafety,
2012             generics: clean_generics(impl_.generics, cx),
2013             trait_,
2014             for_,
2015             items,
2016             polarity: tcx.impl_polarity(def_id),
2017             kind: if utils::has_doc_flag(tcx, def_id.to_def_id(), sym::fake_variadic) {
2018                 ImplKind::FakeVaradic
2019             } else {
2020                 ImplKind::Normal
2021             },
2022         }));
2023         Item::from_hir_id_and_parts(hir_id, None, kind, cx)
2024     };
2025     if let Some(type_alias) = type_alias {
2026         ret.push(make_item(trait_.clone(), type_alias, items.clone()));
2027     }
2028     ret.push(make_item(trait_, for_, items));
2029     ret
2030 }
2031
2032 fn clean_extern_crate<'tcx>(
2033     krate: &hir::Item<'tcx>,
2034     name: Symbol,
2035     orig_name: Option<Symbol>,
2036     cx: &mut DocContext<'tcx>,
2037 ) -> Vec<Item> {
2038     // this is the ID of the `extern crate` statement
2039     let cnum = cx.tcx.extern_mod_stmt_cnum(krate.def_id).unwrap_or(LOCAL_CRATE);
2040     // this is the ID of the crate itself
2041     let crate_def_id = cnum.as_def_id();
2042     let attrs = cx.tcx.hir().attrs(krate.hir_id());
2043     let ty_vis = cx.tcx.visibility(krate.def_id);
2044     let please_inline = ty_vis.is_public()
2045         && attrs.iter().any(|a| {
2046             a.has_name(sym::doc)
2047                 && match a.meta_item_list() {
2048                     Some(l) => attr::list_contains_name(&l, sym::inline),
2049                     None => false,
2050                 }
2051         });
2052
2053     if please_inline {
2054         let mut visited = FxHashSet::default();
2055
2056         let res = Res::Def(DefKind::Mod, crate_def_id);
2057
2058         if let Some(items) = inline::try_inline(
2059             cx,
2060             cx.tcx.parent_module(krate.hir_id()).to_def_id(),
2061             Some(krate.def_id.to_def_id()),
2062             res,
2063             name,
2064             Some(attrs),
2065             &mut visited,
2066         ) {
2067             return items;
2068         }
2069     }
2070
2071     // FIXME: using `from_def_id_and_kind` breaks `rustdoc/masked` for some reason
2072     vec![Item {
2073         name: Some(name),
2074         attrs: Box::new(Attributes::from_ast(attrs)),
2075         item_id: crate_def_id.into(),
2076         visibility: clean_visibility(ty_vis),
2077         kind: Box::new(ExternCrateItem { src: orig_name }),
2078         cfg: attrs.cfg(cx.tcx, &cx.cache.hidden_cfg),
2079     }]
2080 }
2081
2082 fn clean_use_statement<'tcx>(
2083     import: &hir::Item<'tcx>,
2084     name: Symbol,
2085     path: &hir::Path<'tcx>,
2086     kind: hir::UseKind,
2087     cx: &mut DocContext<'tcx>,
2088     inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
2089 ) -> Vec<Item> {
2090     // We need this comparison because some imports (for std types for example)
2091     // are "inserted" as well but directly by the compiler and they should not be
2092     // taken into account.
2093     if import.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
2094         return Vec::new();
2095     }
2096
2097     let visibility = cx.tcx.visibility(import.def_id);
2098     let attrs = cx.tcx.hir().attrs(import.hir_id());
2099     let inline_attr = attrs.lists(sym::doc).get_word_attr(sym::inline);
2100     let pub_underscore = visibility.is_public() && name == kw::Underscore;
2101     let current_mod = cx.tcx.parent_module_from_def_id(import.def_id);
2102
2103     // The parent of the module in which this import resides. This
2104     // is the same as `current_mod` if that's already the top
2105     // level module.
2106     let parent_mod = cx.tcx.parent_module_from_def_id(current_mod);
2107
2108     // This checks if the import can be seen from a higher level module.
2109     // In other words, it checks if the visibility is the equivalent of
2110     // `pub(super)` or higher. If the current module is the top level
2111     // module, there isn't really a parent module, which makes the results
2112     // meaningless. In this case, we make sure the answer is `false`.
2113     let is_visible_from_parent_mod = visibility.is_accessible_from(parent_mod.to_def_id(), cx.tcx)
2114         && !current_mod.is_top_level_module();
2115
2116     if pub_underscore {
2117         if let Some(ref inline) = inline_attr {
2118             rustc_errors::struct_span_err!(
2119                 cx.tcx.sess,
2120                 inline.span(),
2121                 E0780,
2122                 "anonymous imports cannot be inlined"
2123             )
2124             .span_label(import.span, "anonymous import")
2125             .emit();
2126         }
2127     }
2128
2129     // We consider inlining the documentation of `pub use` statements, but we
2130     // forcefully don't inline if this is not public or if the
2131     // #[doc(no_inline)] attribute is present.
2132     // Don't inline doc(hidden) imports so they can be stripped at a later stage.
2133     let mut denied = cx.output_format.is_json()
2134         || !(visibility.is_public()
2135             || (cx.render_options.document_private && is_visible_from_parent_mod))
2136         || pub_underscore
2137         || attrs.iter().any(|a| {
2138             a.has_name(sym::doc)
2139                 && match a.meta_item_list() {
2140                     Some(l) => {
2141                         attr::list_contains_name(&l, sym::no_inline)
2142                             || attr::list_contains_name(&l, sym::hidden)
2143                     }
2144                     None => false,
2145                 }
2146         });
2147
2148     // Also check whether imports were asked to be inlined, in case we're trying to re-export a
2149     // crate in Rust 2018+
2150     let path = clean_path(path, cx);
2151     let inner = if kind == hir::UseKind::Glob {
2152         if !denied {
2153             let mut visited = FxHashSet::default();
2154             if let Some(items) = inline::try_inline_glob(cx, path.res, &mut visited, inlined_names)
2155             {
2156                 return items;
2157             }
2158         }
2159         Import::new_glob(resolve_use_source(cx, path), true)
2160     } else {
2161         if inline_attr.is_none() {
2162             if let Res::Def(DefKind::Mod, did) = path.res {
2163                 if !did.is_local() && did.is_crate_root() {
2164                     // if we're `pub use`ing an extern crate root, don't inline it unless we
2165                     // were specifically asked for it
2166                     denied = true;
2167                 }
2168             }
2169         }
2170         if !denied {
2171             let mut visited = FxHashSet::default();
2172             let import_def_id = import.def_id.to_def_id();
2173
2174             if let Some(mut items) = inline::try_inline(
2175                 cx,
2176                 cx.tcx.parent_module(import.hir_id()).to_def_id(),
2177                 Some(import_def_id),
2178                 path.res,
2179                 name,
2180                 Some(attrs),
2181                 &mut visited,
2182             ) {
2183                 items.push(Item::from_def_id_and_parts(
2184                     import_def_id,
2185                     None,
2186                     ImportItem(Import::new_simple(name, resolve_use_source(cx, path), false)),
2187                     cx,
2188                 ));
2189                 return items;
2190             }
2191         }
2192         Import::new_simple(name, resolve_use_source(cx, path), true)
2193     };
2194
2195     vec![Item::from_def_id_and_parts(import.def_id.to_def_id(), None, ImportItem(inner), cx)]
2196 }
2197
2198 fn clean_maybe_renamed_foreign_item<'tcx>(
2199     cx: &mut DocContext<'tcx>,
2200     item: &hir::ForeignItem<'tcx>,
2201     renamed: Option<Symbol>,
2202 ) -> Item {
2203     let def_id = item.def_id.to_def_id();
2204     cx.with_param_env(def_id, |cx| {
2205         let kind = match item.kind {
2206             hir::ForeignItemKind::Fn(decl, names, generics) => {
2207                 let (generics, decl) = enter_impl_trait(cx, |cx| {
2208                     // NOTE: generics must be cleaned before args
2209                     let generics = clean_generics(generics, cx);
2210                     let args = clean_args_from_types_and_names(cx, decl.inputs, names);
2211                     let decl = clean_fn_decl_with_args(cx, decl, args);
2212                     (generics, decl)
2213                 });
2214                 ForeignFunctionItem(Box::new(Function { decl, generics }))
2215             }
2216             hir::ForeignItemKind::Static(ty, mutability) => {
2217                 ForeignStaticItem(Static { type_: clean_ty(ty, cx), mutability, expr: None })
2218             }
2219             hir::ForeignItemKind::Type => ForeignTypeItem,
2220         };
2221
2222         Item::from_hir_id_and_parts(
2223             item.hir_id(),
2224             Some(renamed.unwrap_or(item.ident.name)),
2225             kind,
2226             cx,
2227         )
2228     })
2229 }
2230
2231 fn clean_type_binding<'tcx>(
2232     type_binding: &hir::TypeBinding<'tcx>,
2233     cx: &mut DocContext<'tcx>,
2234 ) -> TypeBinding {
2235     TypeBinding {
2236         assoc: PathSegment {
2237             name: type_binding.ident.name,
2238             args: clean_generic_args(type_binding.gen_args, cx),
2239         },
2240         kind: match type_binding.kind {
2241             hir::TypeBindingKind::Equality { ref term } => {
2242                 TypeBindingKind::Equality { term: clean_hir_term(term, cx) }
2243             }
2244             hir::TypeBindingKind::Constraint { bounds } => TypeBindingKind::Constraint {
2245                 bounds: bounds.iter().filter_map(|b| clean_generic_bound(b, cx)).collect(),
2246             },
2247         },
2248     }
2249 }