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_hir_analysis::hir_ty_to_ty;
  21 use rustc_infer::infer::region_constraints::{Constraint, RegionConstraintData};
  22 use rustc_middle::middle::resolve_lifetime as rl;
  23 use rustc_middle::ty::fold::TypeFolder;
  24 use rustc_middle::ty::InternalSubsts;
  25 use rustc_middle::ty::{self, AdtKind, DefIdTree, EarlyBinder, Ty, TyCtxt};
  26 use rustc_middle::{bug, span_bug};
  27 use rustc_span::hygiene::{AstPass, MacroKind};
  28 use rustc_span::symbol::{kw, sym, Ident, Symbol};
  29 use rustc_span::{self, ExpnKind};
  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;
  37 use thin_vec::ThinVec;
  38
  39 use crate::core::{self, DocContext, ImplTraitParam};
  40 use crate::formats::item_type::ItemType;
  41 use crate::visit_ast::Module as DocModule;
  42
  43 use utils::*;
  44
  45 pub(crate) use self::types::*;
  46 pub(crate) use self::utils::{get_auto_trait_and_blanket_impls, krate, register_res};
  47
  48 pub(crate) fn clean_doc_module<'tcx>(doc: &DocModule<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
  49     let mut items: Vec<Item> = vec![];
  50     let mut inserted = FxHashSet::default();
  51     items.extend(doc.foreigns.iter().map(|(item, renamed)| {
  52         let item = clean_maybe_renamed_foreign_item(cx, item, *renamed);
  53         if let Some(name) = item.name && !item.attrs.lists(sym::doc).has_word(sym::hidden) {
  54             inserted.insert((item.type_(), name));
  55         }
  56         item
  57     }));
  58     items.extend(doc.mods.iter().filter_map(|x| {
  59         if !inserted.insert((ItemType::Module, x.name)) {
  60             return None;
  61         }
  62         let item = clean_doc_module(x, cx);
  63         if item.attrs.lists(sym::doc).has_word(sym::hidden) {
  64             // Hidden modules are stripped at a later stage.
  65             // If a hidden module has the same name as a visible one, we want
  66             // to keep both of them around.
  67             inserted.remove(&(ItemType::Module, x.name));
  68         }
  69         Some(item)
  70     }));
  71
  72     // Split up imports from all other items.
  73     //
  74     // This covers the case where somebody does an import which should pull in an item,
  75     // but there's already an item with the same namespace and same name. Rust gives
  76     // priority to the not-imported one, so we should, too.
  77     items.extend(doc.items.iter().flat_map(|(item, renamed, import_id)| {
  78         // First, lower everything other than imports.
  79         if matches!(item.kind, hir::ItemKind::Use(_, hir::UseKind::Glob)) {
  80             return Vec::new();
  81         }
  82         let v = clean_maybe_renamed_item(cx, item, *renamed, *import_id);
  83         for item in &v {
  84             if let Some(name) = item.name && !item.attrs.lists(sym::doc).has_word(sym::hidden) {
  85                 inserted.insert((item.type_(), name));
  86             }
  87         }
  88         v
  89     }));
  90     items.extend(doc.items.iter().flat_map(|(item, renamed, _)| {
  91         // Now we actually lower the imports, skipping everything else.
  92         if let hir::ItemKind::Use(path, hir::UseKind::Glob) = item.kind {
  93             let name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
  94             clean_use_statement(item, name, path, hir::UseKind::Glob, cx, &mut inserted)
  95         } else {
  96             // skip everything else
  97             Vec::new()
  98         }
  99     }));
 100
 101     // determine if we should display the inner contents or
 102     // the outer `mod` item for the source code.
 103
 104     let span = Span::new({
 105         let where_outer = doc.where_outer(cx.tcx);
 106         let sm = cx.sess().source_map();
 107         let outer = sm.lookup_char_pos(where_outer.lo());
 108         let inner = sm.lookup_char_pos(doc.where_inner.lo());
 109         if outer.file.start_pos == inner.file.start_pos {
 110             // mod foo { ... }
 111             where_outer
 112         } else {
 113             // mod foo; (and a separate SourceFile for the contents)
 114             doc.where_inner
 115         }
 116     });
 117
 118     Item::from_hir_id_and_parts(doc.id, Some(doc.name), ModuleItem(Module { items, span }), cx)
 119 }
 120
 121 fn clean_generic_bound<'tcx>(
 122     bound: &hir::GenericBound<'tcx>,
 123     cx: &mut DocContext<'tcx>,
 124 ) -> Option<GenericBound> {
 125     Some(match *bound {
 126         hir::GenericBound::Outlives(lt) => GenericBound::Outlives(clean_lifetime(lt, cx)),
 127         hir::GenericBound::LangItemTrait(lang_item, span, _, generic_args) => {
 128             let def_id = cx.tcx.require_lang_item(lang_item, Some(span));
 129
 130             let trait_ref = ty::TraitRef::identity(cx.tcx, def_id).skip_binder();
 131
 132             let generic_args = clean_generic_args(generic_args, cx);
 133             let GenericArgs::AngleBracketed { bindings, .. } = generic_args
 134             else {
 135                 bug!("clean: parenthesized `GenericBound::LangItemTrait`");
 136             };
 137
 138             let trait_ = clean_trait_ref_with_bindings(cx, trait_ref, bindings);
 139             GenericBound::TraitBound(
 140                 PolyTrait { trait_, generic_params: vec![] },
 141                 hir::TraitBoundModifier::None,
 142             )
 143         }
 144         hir::GenericBound::Trait(ref t, modifier) => {
 145             // `T: ~const Destruct` is hidden because `T: Destruct` is a no-op.
 146             if modifier == hir::TraitBoundModifier::MaybeConst
 147                 && cx.tcx.lang_items().destruct_trait() == Some(t.trait_ref.trait_def_id().unwrap())
 148             {
 149                 return None;
 150             }
 151
 152             GenericBound::TraitBound(clean_poly_trait_ref(t, cx), modifier)
 153         }
 154     })
 155 }
 156
 157 pub(crate) fn clean_trait_ref_with_bindings<'tcx>(
 158     cx: &mut DocContext<'tcx>,
 159     trait_ref: ty::TraitRef<'tcx>,
 160     bindings: ThinVec<TypeBinding>,
 161 ) -> Path {
 162     let kind = cx.tcx.def_kind(trait_ref.def_id).into();
 163     if !matches!(kind, ItemType::Trait | ItemType::TraitAlias) {
 164         span_bug!(cx.tcx.def_span(trait_ref.def_id), "`TraitRef` had unexpected kind {:?}", kind);
 165     }
 166     inline::record_extern_fqn(cx, trait_ref.def_id, kind);
 167     let path = external_path(cx, trait_ref.def_id, true, bindings, trait_ref.substs);
 168
 169     debug!("ty::TraitRef\n  subst: {:?}\n", trait_ref.substs);
 170
 171     path
 172 }
 173
 174 fn clean_poly_trait_ref_with_bindings<'tcx>(
 175     cx: &mut DocContext<'tcx>,
 176     poly_trait_ref: ty::PolyTraitRef<'tcx>,
 177     bindings: ThinVec<TypeBinding>,
 178 ) -> GenericBound {
 179     // collect any late bound regions
 180     let late_bound_regions: Vec<_> = cx
 181         .tcx
 182         .collect_referenced_late_bound_regions(&poly_trait_ref)
 183         .into_iter()
 184         .filter_map(|br| match br {
 185             ty::BrNamed(_, name) if name != kw::UnderscoreLifetime => Some(GenericParamDef {
 186                 name,
 187                 kind: GenericParamDefKind::Lifetime { outlives: vec![] },
 188             }),
 189             _ => None,
 190         })
 191         .collect();
 192
 193     let trait_ = clean_trait_ref_with_bindings(cx, poly_trait_ref.skip_binder(), bindings);
 194     GenericBound::TraitBound(
 195         PolyTrait { trait_, generic_params: late_bound_regions },
 196         hir::TraitBoundModifier::None,
 197     )
 198 }
 199
 200 fn clean_lifetime<'tcx>(lifetime: &hir::Lifetime, cx: &mut DocContext<'tcx>) -> Lifetime {
 201     let def = cx.tcx.named_region(lifetime.hir_id);
 202     if let Some(
 203         rl::Region::EarlyBound(node_id)
 204         | rl::Region::LateBound(_, _, node_id)
 205         | rl::Region::Free(_, node_id),
 206     ) = def
 207     {
 208         if let Some(lt) = cx.substs.get(&node_id).and_then(|p| p.as_lt()).cloned() {
 209             return lt;
 210         }
 211     }
 212     Lifetime(lifetime.name.ident().name)
 213 }
 214
 215 pub(crate) fn clean_const<'tcx>(constant: &hir::ConstArg, cx: &mut DocContext<'tcx>) -> Constant {
 216     let def_id = cx.tcx.hir().body_owner_def_id(constant.value.body).to_def_id();
 217     Constant {
 218         type_: clean_middle_ty(cx.tcx.type_of(def_id), cx, Some(def_id)),
 219         kind: ConstantKind::Anonymous { body: constant.value.body },
 220     }
 221 }
 222
 223 pub(crate) fn clean_middle_const<'tcx>(
 224     constant: ty::Const<'tcx>,
 225     cx: &mut DocContext<'tcx>,
 226 ) -> Constant {
 227     // FIXME: instead of storing the stringified expression, store `self` directly instead.
 228     Constant {
 229         type_: clean_middle_ty(constant.ty(), cx, None),
 230         kind: ConstantKind::TyConst { expr: constant.to_string() },
 231     }
 232 }
 233
 234 pub(crate) fn clean_middle_region<'tcx>(region: ty::Region<'tcx>) -> Option<Lifetime> {
 235     match *region {
 236         ty::ReStatic => Some(Lifetime::statik()),
 237         ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) => {
 238             if name != kw::UnderscoreLifetime { Some(Lifetime(name)) } else { None }
 239         }
 240         ty::ReEarlyBound(ref data) => {
 241             if data.name != kw::UnderscoreLifetime {
 242                 Some(Lifetime(data.name))
 243             } else {
 244                 None
 245             }
 246         }
 247         ty::ReLateBound(..)
 248         | ty::ReFree(..)
 249         | ty::ReVar(..)
 250         | ty::RePlaceholder(..)
 251         | ty::ReErased => {
 252             debug!("cannot clean region {:?}", region);
 253             None
 254         }
 255     }
 256 }
 257
 258 fn clean_where_predicate<'tcx>(
 259     predicate: &hir::WherePredicate<'tcx>,
 260     cx: &mut DocContext<'tcx>,
 261 ) -> Option<WherePredicate> {
 262     if !predicate.in_where_clause() {
 263         return None;
 264     }
 265     Some(match *predicate {
 266         hir::WherePredicate::BoundPredicate(ref wbp) => {
 267             let bound_params = wbp
 268                 .bound_generic_params
 269                 .iter()
 270                 .map(|param| {
 271                     // Higher-ranked params must be lifetimes.
 272                     // Higher-ranked lifetimes can't have bounds.
 273                     assert_matches!(
 274                         param,
 275                         hir::GenericParam { kind: hir::GenericParamKind::Lifetime { .. }, .. }
 276                     );
 277                     Lifetime(param.name.ident().name)
 278                 })
 279                 .collect();
 280             WherePredicate::BoundPredicate {
 281                 ty: clean_ty(wbp.bounded_ty, cx),
 282                 bounds: wbp.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
 283                 bound_params,
 284             }
 285         }
 286
 287         hir::WherePredicate::RegionPredicate(ref wrp) => WherePredicate::RegionPredicate {
 288             lifetime: clean_lifetime(wrp.lifetime, cx),
 289             bounds: wrp.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
 290         },
 291
 292         hir::WherePredicate::EqPredicate(ref wrp) => WherePredicate::EqPredicate {
 293             lhs: Box::new(clean_ty(wrp.lhs_ty, cx)),
 294             rhs: Box::new(clean_ty(wrp.rhs_ty, cx).into()),
 295             bound_params: Vec::new(),
 296         },
 297     })
 298 }
 299
 300 pub(crate) fn clean_predicate<'tcx>(
 301     predicate: ty::Predicate<'tcx>,
 302     cx: &mut DocContext<'tcx>,
 303 ) -> Option<WherePredicate> {
 304     let bound_predicate = predicate.kind();
 305     match bound_predicate.skip_binder() {
 306         ty::PredicateKind::Trait(pred) => {
 307             clean_poly_trait_predicate(bound_predicate.rebind(pred), cx)
 308         }
 309         ty::PredicateKind::RegionOutlives(pred) => clean_region_outlives_predicate(pred),
 310         ty::PredicateKind::TypeOutlives(pred) => clean_type_outlives_predicate(pred, cx),
 311         ty::PredicateKind::Projection(pred) => {
 312             Some(clean_projection_predicate(bound_predicate.rebind(pred), cx))
 313         }
 314         ty::PredicateKind::ConstEvaluatable(..) => None,
 315         ty::PredicateKind::WellFormed(..) => None,
 316
 317         ty::PredicateKind::Subtype(..)
 318         | ty::PredicateKind::Coerce(..)
 319         | ty::PredicateKind::ObjectSafe(..)
 320         | ty::PredicateKind::ClosureKind(..)
 321         | ty::PredicateKind::ConstEquate(..)
 322         | ty::PredicateKind::TypeWellFormedFromEnv(..) => panic!("not user writable"),
 323     }
 324 }
 325
 326 fn clean_poly_trait_predicate<'tcx>(
 327     pred: ty::PolyTraitPredicate<'tcx>,
 328     cx: &mut DocContext<'tcx>,
 329 ) -> Option<WherePredicate> {
 330     // `T: ~const Destruct` is hidden because `T: Destruct` is a no-op.
 331     if pred.skip_binder().constness == ty::BoundConstness::ConstIfConst
 332         && Some(pred.skip_binder().def_id()) == cx.tcx.lang_items().destruct_trait()
 333     {
 334         return None;
 335     }
 336
 337     let poly_trait_ref = pred.map_bound(|pred| pred.trait_ref);
 338     Some(WherePredicate::BoundPredicate {
 339         ty: clean_middle_ty(poly_trait_ref.skip_binder().self_ty(), cx, None),
 340         bounds: vec![clean_poly_trait_ref_with_bindings(cx, poly_trait_ref, ThinVec::new())],
 341         bound_params: Vec::new(),
 342     })
 343 }
 344
 345 fn clean_region_outlives_predicate<'tcx>(
 346     pred: ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>,
 347 ) -> Option<WherePredicate> {
 348     let ty::OutlivesPredicate(a, b) = pred;
 349
 350     Some(WherePredicate::RegionPredicate {
 351         lifetime: clean_middle_region(a).expect("failed to clean lifetime"),
 352         bounds: vec![GenericBound::Outlives(
 353             clean_middle_region(b).expect("failed to clean bounds"),
 354         )],
 355     })
 356 }
 357
 358 fn clean_type_outlives_predicate<'tcx>(
 359     pred: ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>,
 360     cx: &mut DocContext<'tcx>,
 361 ) -> Option<WherePredicate> {
 362     let ty::OutlivesPredicate(ty, lt) = pred;
 363
 364     Some(WherePredicate::BoundPredicate {
 365         ty: clean_middle_ty(ty, cx, None),
 366         bounds: vec![GenericBound::Outlives(
 367             clean_middle_region(lt).expect("failed to clean lifetimes"),
 368         )],
 369         bound_params: Vec::new(),
 370     })
 371 }
 372
 373 fn clean_middle_term<'tcx>(term: ty::Term<'tcx>, cx: &mut DocContext<'tcx>) -> Term {
 374     match term.unpack() {
 375         ty::TermKind::Ty(ty) => Term::Type(clean_middle_ty(ty, cx, None)),
 376         ty::TermKind::Const(c) => Term::Constant(clean_middle_const(c, cx)),
 377     }
 378 }
 379
 380 fn clean_hir_term<'tcx>(term: &hir::Term<'tcx>, cx: &mut DocContext<'tcx>) -> Term {
 381     match term {
 382         hir::Term::Ty(ty) => Term::Type(clean_ty(ty, cx)),
 383         hir::Term::Const(c) => {
 384             let def_id = cx.tcx.hir().local_def_id(c.hir_id);
 385             Term::Constant(clean_middle_const(ty::Const::from_anon_const(cx.tcx, def_id), cx))
 386         }
 387     }
 388 }
 389
 390 fn clean_projection_predicate<'tcx>(
 391     pred: ty::Binder<'tcx, ty::ProjectionPredicate<'tcx>>,
 392     cx: &mut DocContext<'tcx>,
 393 ) -> WherePredicate {
 394     let late_bound_regions = cx
 395         .tcx
 396         .collect_referenced_late_bound_regions(&pred)
 397         .into_iter()
 398         .filter_map(|br| match br {
 399             ty::BrNamed(_, name) if name != kw::UnderscoreLifetime => Some(Lifetime(name)),
 400             _ => None,
 401         })
 402         .collect();
 403
 404     let ty::ProjectionPredicate { projection_ty, term } = pred.skip_binder();
 405
 406     WherePredicate::EqPredicate {
 407         lhs: Box::new(clean_projection(projection_ty, cx, None)),
 408         rhs: Box::new(clean_middle_term(term, cx)),
 409         bound_params: late_bound_regions,
 410     }
 411 }
 412
 413 fn clean_projection<'tcx>(
 414     ty: ty::ProjectionTy<'tcx>,
 415     cx: &mut DocContext<'tcx>,
 416     def_id: Option<DefId>,
 417 ) -> Type {
 418     if cx.tcx.def_kind(ty.item_def_id) == DefKind::ImplTraitPlaceholder {
 419         let bounds = cx
 420             .tcx
 421             .explicit_item_bounds(ty.item_def_id)
 422             .iter()
 423             .map(|(bound, _)| EarlyBinder(*bound).subst(cx.tcx, ty.substs))
 424             .collect::<Vec<_>>();
 425         return clean_middle_opaque_bounds(cx, bounds);
 426     }
 427
 428     let trait_ = clean_trait_ref_with_bindings(cx, ty.trait_ref(cx.tcx), ThinVec::new());
 429     let self_type = clean_middle_ty(ty.self_ty(), cx, None);
 430     let self_def_id = if let Some(def_id) = def_id {
 431         cx.tcx.opt_parent(def_id).or(Some(def_id))
 432     } else {
 433         self_type.def_id(&cx.cache)
 434     };
 435     let should_show_cast = compute_should_show_cast(self_def_id, &trait_, &self_type);
 436     Type::QPath(Box::new(QPathData {
 437         assoc: projection_to_path_segment(ty, cx),
 438         should_show_cast,
 439         self_type,
 440         trait_,
 441     }))
 442 }
 443
 444 fn compute_should_show_cast(self_def_id: Option<DefId>, trait_: &Path, self_type: &Type) -> bool {
 445     !trait_.segments.is_empty()
 446         && self_def_id
 447             .zip(Some(trait_.def_id()))
 448             .map_or(!self_type.is_self_type(), |(id, trait_)| id != trait_)
 449 }
 450
 451 fn projection_to_path_segment<'tcx>(
 452     ty: ty::ProjectionTy<'tcx>,
 453     cx: &mut DocContext<'tcx>,
 454 ) -> PathSegment {
 455     let item = cx.tcx.associated_item(ty.item_def_id);
 456     let generics = cx.tcx.generics_of(ty.item_def_id);
 457     PathSegment {
 458         name: item.name,
 459         args: GenericArgs::AngleBracketed {
 460             args: substs_to_args(cx, &ty.substs[generics.parent_count..], false).into(),
 461             bindings: Default::default(),
 462         },
 463     }
 464 }
 465
 466 fn clean_generic_param_def<'tcx>(
 467     def: &ty::GenericParamDef,
 468     cx: &mut DocContext<'tcx>,
 469 ) -> GenericParamDef {
 470     let (name, kind) = match def.kind {
 471         ty::GenericParamDefKind::Lifetime => {
 472             (def.name, GenericParamDefKind::Lifetime { outlives: vec![] })
 473         }
 474         ty::GenericParamDefKind::Type { has_default, synthetic, .. } => {
 475             let default = if has_default {
 476                 Some(clean_middle_ty(cx.tcx.type_of(def.def_id), cx, Some(def.def_id)))
 477             } else {
 478                 None
 479             };
 480             (
 481                 def.name,
 482                 GenericParamDefKind::Type {
 483                     did: def.def_id,
 484                     bounds: vec![], // These are filled in from the where-clauses.
 485                     default: default.map(Box::new),
 486                     synthetic,
 487                 },
 488             )
 489         }
 490         ty::GenericParamDefKind::Const { has_default } => (
 491             def.name,
 492             GenericParamDefKind::Const {
 493                 did: def.def_id,
 494                 ty: Box::new(clean_middle_ty(cx.tcx.type_of(def.def_id), cx, Some(def.def_id))),
 495                 default: match has_default {
 496                     true => Some(Box::new(cx.tcx.const_param_default(def.def_id).to_string())),
 497                     false => None,
 498                 },
 499             },
 500         ),
 501     };
 502
 503     GenericParamDef { name, kind }
 504 }
 505
 506 fn clean_generic_param<'tcx>(
 507     cx: &mut DocContext<'tcx>,
 508     generics: Option<&hir::Generics<'tcx>>,
 509     param: &hir::GenericParam<'tcx>,
 510 ) -> GenericParamDef {
 511     let did = cx.tcx.hir().local_def_id(param.hir_id);
 512     let (name, kind) = match param.kind {
 513         hir::GenericParamKind::Lifetime { .. } => {
 514             let outlives = if let Some(generics) = generics {
 515                 generics
 516                     .outlives_for_param(did)
 517                     .filter(|bp| !bp.in_where_clause)
 518                     .flat_map(|bp| bp.bounds)
 519                     .map(|bound| match bound {
 520                         hir::GenericBound::Outlives(lt) => clean_lifetime(lt, cx),
 521                         _ => panic!(),
 522                     })
 523                     .collect()
 524             } else {
 525                 Vec::new()
 526             };
 527             (param.name.ident().name, GenericParamDefKind::Lifetime { outlives })
 528         }
 529         hir::GenericParamKind::Type { ref default, synthetic } => {
 530             let bounds = if let Some(generics) = generics {
 531                 generics
 532                     .bounds_for_param(did)
 533                     .filter(|bp| bp.origin != PredicateOrigin::WhereClause)
 534                     .flat_map(|bp| bp.bounds)
 535                     .filter_map(|x| clean_generic_bound(x, cx))
 536                     .collect()
 537             } else {
 538                 Vec::new()
 539             };
 540             (
 541                 param.name.ident().name,
 542                 GenericParamDefKind::Type {
 543                     did: did.to_def_id(),
 544                     bounds,
 545                     default: default.map(|t| clean_ty(t, cx)).map(Box::new),
 546                     synthetic,
 547                 },
 548             )
 549         }
 550         hir::GenericParamKind::Const { ty, default } => (
 551             param.name.ident().name,
 552             GenericParamDefKind::Const {
 553                 did: did.to_def_id(),
 554                 ty: Box::new(clean_ty(ty, cx)),
 555                 default: default.map(|ct| {
 556                     let def_id = cx.tcx.hir().local_def_id(ct.hir_id);
 557                     Box::new(ty::Const::from_anon_const(cx.tcx, def_id).to_string())
 558                 }),
 559             },
 560         ),
 561     };
 562
 563     GenericParamDef { name, kind }
 564 }
 565
 566 /// Synthetic type-parameters are inserted after normal ones.
 567 /// In order for normal parameters to be able to refer to synthetic ones,
 568 /// scans them first.
 569 fn is_impl_trait(param: &hir::GenericParam<'_>) -> bool {
 570     match param.kind {
 571         hir::GenericParamKind::Type { synthetic, .. } => synthetic,
 572         _ => false,
 573     }
 574 }
 575
 576 /// This can happen for `async fn`, e.g. `async fn f<'_>(&'_ self)`.
 577 ///
 578 /// See `lifetime_to_generic_param` in `rustc_ast_lowering` for more information.
 579 fn is_elided_lifetime(param: &hir::GenericParam<'_>) -> bool {
 580     matches!(param.kind, hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided })
 581 }
 582
 583 pub(crate) fn clean_generics<'tcx>(
 584     gens: &hir::Generics<'tcx>,
 585     cx: &mut DocContext<'tcx>,
 586 ) -> Generics {
 587     let impl_trait_params = gens
 588         .params
 589         .iter()
 590         .filter(|param| is_impl_trait(param))
 591         .map(|param| {
 592             let param = clean_generic_param(cx, Some(gens), param);
 593             match param.kind {
 594                 GenericParamDefKind::Lifetime { .. } => unreachable!(),
 595                 GenericParamDefKind::Type { did, ref bounds, .. } => {
 596                     cx.impl_trait_bounds.insert(did.into(), bounds.clone());
 597                 }
 598                 GenericParamDefKind::Const { .. } => unreachable!(),
 599             }
 600             param
 601         })
 602         .collect::<Vec<_>>();
 603
 604     let mut params = ThinVec::with_capacity(gens.params.len());
 605     for p in gens.params.iter().filter(|p| !is_impl_trait(p) && !is_elided_lifetime(p)) {
 606         let p = clean_generic_param(cx, Some(gens), p);
 607         params.push(p);
 608     }
 609     params.extend(impl_trait_params);
 610
 611     let mut generics = Generics {
 612         params,
 613         where_predicates: gens
 614             .predicates
 615             .iter()
 616             .filter_map(|x| clean_where_predicate(x, cx))
 617             .collect(),
 618     };
 619
 620     // Some duplicates are generated for ?Sized bounds between type params and where
 621     // predicates. The point in here is to move the bounds definitions from type params
 622     // to where predicates when such cases occur.
 623     for where_pred in &mut generics.where_predicates {
 624         match *where_pred {
 625             WherePredicate::BoundPredicate { ty: Generic(ref name), ref mut bounds, .. } => {
 626                 if bounds.is_empty() {
 627                     for param in &mut generics.params {
 628                         match param.kind {
 629                             GenericParamDefKind::Lifetime { .. } => {}
 630                             GenericParamDefKind::Type { bounds: ref mut ty_bounds, .. } => {
 631                                 if &param.name == name {
 632                                     mem::swap(bounds, ty_bounds);
 633                                     break;
 634                                 }
 635                             }
 636                             GenericParamDefKind::Const { .. } => {}
 637                         }
 638                     }
 639                 }
 640             }
 641             _ => continue,
 642         }
 643     }
 644     generics
 645 }
 646
 647 fn clean_ty_generics<'tcx>(
 648     cx: &mut DocContext<'tcx>,
 649     gens: &ty::Generics,
 650     preds: ty::GenericPredicates<'tcx>,
 651 ) -> Generics {
 652     // Don't populate `cx.impl_trait_bounds` before `clean`ning `where` clauses,
 653     // since `Clean for ty::Predicate` would consume them.
 654     let mut impl_trait = BTreeMap::<ImplTraitParam, Vec<GenericBound>>::default();
 655
 656     // Bounds in the type_params and lifetimes fields are repeated in the
 657     // predicates field (see rustc_hir_analysis::collect::ty_generics), so remove
 658     // them.
 659     let stripped_params = gens
 660         .params
 661         .iter()
 662         .filter_map(|param| match param.kind {
 663             ty::GenericParamDefKind::Lifetime if param.name == kw::UnderscoreLifetime => None,
 664             ty::GenericParamDefKind::Lifetime => Some(clean_generic_param_def(param, cx)),
 665             ty::GenericParamDefKind::Type { synthetic, .. } => {
 666                 if param.name == kw::SelfUpper {
 667                     assert_eq!(param.index, 0);
 668                     return None;
 669                 }
 670                 if synthetic {
 671                     impl_trait.insert(param.index.into(), vec![]);
 672                     return None;
 673                 }
 674                 Some(clean_generic_param_def(param, cx))
 675             }
 676             ty::GenericParamDefKind::Const { .. } => Some(clean_generic_param_def(param, cx)),
 677         })
 678         .collect::<ThinVec<GenericParamDef>>();
 679
 680     // param index -> [(trait DefId, associated type name & generics, type, higher-ranked params)]
 681     let mut impl_trait_proj =
 682         FxHashMap::<u32, Vec<(DefId, PathSegment, Ty<'_>, Vec<GenericParamDef>)>>::default();
 683
 684     let where_predicates = preds
 685         .predicates
 686         .iter()
 687         .flat_map(|(p, _)| {
 688             let mut projection = None;
 689             let param_idx = (|| {
 690                 let bound_p = p.kind();
 691                 match bound_p.skip_binder() {
 692                     ty::PredicateKind::Trait(pred) => {
 693                         if let ty::Param(param) = pred.self_ty().kind() {
 694                             return Some(param.index);
 695                         }
 696                     }
 697                     ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty, _reg)) => {
 698                         if let ty::Param(param) = ty.kind() {
 699                             return Some(param.index);
 700                         }
 701                     }
 702                     ty::PredicateKind::Projection(p) => {
 703                         if let ty::Param(param) = p.projection_ty.self_ty().kind() {
 704                             projection = Some(bound_p.rebind(p));
 705                             return Some(param.index);
 706                         }
 707                     }
 708                     _ => (),
 709                 }
 710
 711                 None
 712             })();
 713
 714             if let Some(param_idx) = param_idx {
 715                 if let Some(b) = impl_trait.get_mut(&param_idx.into()) {
 716                     let p: WherePredicate = clean_predicate(*p, cx)?;
 717
 718                     b.extend(
 719                         p.get_bounds()
 720                             .into_iter()
 721                             .flatten()
 722                             .cloned()
 723                             .filter(|b| !b.is_sized_bound(cx)),
 724                     );
 725
 726                     let proj = projection.map(|p| {
 727                         (
 728                             clean_projection(p.skip_binder().projection_ty, cx, None),
 729                             p.skip_binder().term,
 730                         )
 731                     });
 732                     if let Some(((_, trait_did, name), rhs)) = proj
 733                         .as_ref()
 734                         .and_then(|(lhs, rhs): &(Type, _)| Some((lhs.projection()?, rhs)))
 735                     {
 736                         // FIXME(...): Remove this unwrap()
 737                         impl_trait_proj.entry(param_idx).or_default().push((
 738                             trait_did,
 739                             name,
 740                             rhs.ty().unwrap(),
 741                             p.get_bound_params()
 742                                 .into_iter()
 743                                 .flatten()
 744                                 .map(|param| GenericParamDef {
 745                                     name: param.0,
 746                                     kind: GenericParamDefKind::Lifetime { outlives: Vec::new() },
 747                                 })
 748                                 .collect(),
 749                         ));
 750                     }
 751
 752                     return None;
 753                 }
 754             }
 755
 756             Some(p)
 757         })
 758         .collect::<Vec<_>>();
 759
 760     for (param, mut bounds) in impl_trait {
 761         // Move trait bounds to the front.
 762         bounds.sort_by_key(|b| !matches!(b, GenericBound::TraitBound(..)));
 763
 764         let crate::core::ImplTraitParam::ParamIndex(idx) = param else { unreachable!() };
 765         if let Some(proj) = impl_trait_proj.remove(&idx) {
 766             for (trait_did, name, rhs, bound_params) in proj {
 767                 let rhs = clean_middle_ty(rhs, cx, None);
 768                 simplify::merge_bounds(
 769                     cx,
 770                     &mut bounds,
 771                     bound_params,
 772                     trait_did,
 773                     name,
 774                     &Term::Type(rhs),
 775                 );
 776             }
 777         }
 778
 779         cx.impl_trait_bounds.insert(param, bounds);
 780     }
 781
 782     // Now that `cx.impl_trait_bounds` is populated, we can process
 783     // remaining predicates which could contain `impl Trait`.
 784     let mut where_predicates =
 785         where_predicates.into_iter().flat_map(|p| clean_predicate(*p, cx)).collect::<Vec<_>>();
 786
 787     // In the surface language, all type parameters except `Self` have an
 788     // implicit `Sized` bound unless removed with `?Sized`.
 789     // However, in the list of where-predicates below, `Sized` appears like a
 790     // normal bound: It's either present (the type is sized) or
 791     // absent (the type is unsized) but never *maybe* (i.e. `?Sized`).
 792     //
 793     // This is unsuitable for rendering.
 794     // Thus, as a first step remove all `Sized` bounds that should be implicit.
 795     //
 796     // Note that associated types also have an implicit `Sized` bound but we
 797     // don't actually know the set of associated types right here so that's
 798     // handled when cleaning associated types.
 799     let mut sized_params = FxHashSet::default();
 800     where_predicates.retain(|pred| {
 801         if let WherePredicate::BoundPredicate { ty: Generic(g), bounds, .. } = pred
 802         && *g != kw::SelfUpper
 803         && bounds.iter().any(|b| b.is_sized_bound(cx))
 804         {
 805             sized_params.insert(*g);
 806             false
 807         } else {
 808             true
 809         }
 810     });
 811
 812     // As a final step, go through the type parameters again and insert a
 813     // `?Sized` bound for each one we didn't find to be `Sized`.
 814     for tp in &stripped_params {
 815         if let types::GenericParamDefKind::Type { .. } = tp.kind
 816         && !sized_params.contains(&tp.name)
 817         {
 818             where_predicates.push(WherePredicate::BoundPredicate {
 819                 ty: Type::Generic(tp.name),
 820                 bounds: vec![GenericBound::maybe_sized(cx)],
 821                 bound_params: Vec::new(),
 822             })
 823         }
 824     }
 825
 826     // It would be nice to collect all of the bounds on a type and recombine
 827     // them if possible, to avoid e.g., `where T: Foo, T: Bar, T: Sized, T: 'a`
 828     // and instead see `where T: Foo + Bar + Sized + 'a`
 829
 830     Generics {
 831         params: stripped_params,
 832         where_predicates: simplify::where_clauses(cx, where_predicates),
 833     }
 834 }
 835
 836 fn clean_fn_or_proc_macro<'tcx>(
 837     item: &hir::Item<'tcx>,
 838     sig: &hir::FnSig<'tcx>,
 839     generics: &hir::Generics<'tcx>,
 840     body_id: hir::BodyId,
 841     name: &mut Symbol,
 842     cx: &mut DocContext<'tcx>,
 843 ) -> ItemKind {
 844     let attrs = cx.tcx.hir().attrs(item.hir_id());
 845     let macro_kind = attrs.iter().find_map(|a| {
 846         if a.has_name(sym::proc_macro) {
 847             Some(MacroKind::Bang)
 848         } else if a.has_name(sym::proc_macro_derive) {
 849             Some(MacroKind::Derive)
 850         } else if a.has_name(sym::proc_macro_attribute) {
 851             Some(MacroKind::Attr)
 852         } else {
 853             None
 854         }
 855     });
 856     match macro_kind {
 857         Some(kind) => {
 858             if kind == MacroKind::Derive {
 859                 *name = attrs
 860                     .lists(sym::proc_macro_derive)
 861                     .find_map(|mi| mi.ident())
 862                     .expect("proc-macro derives require a name")
 863                     .name;
 864             }
 865
 866             let mut helpers = Vec::new();
 867             for mi in attrs.lists(sym::proc_macro_derive) {
 868                 if !mi.has_name(sym::attributes) {
 869                     continue;
 870                 }
 871
 872                 if let Some(list) = mi.meta_item_list() {
 873                     for inner_mi in list {
 874                         if let Some(ident) = inner_mi.ident() {
 875                             helpers.push(ident.name);
 876                         }
 877                     }
 878                 }
 879             }
 880             ProcMacroItem(ProcMacro { kind, helpers })
 881         }
 882         None => {
 883             let mut func = clean_function(cx, sig, generics, FunctionArgs::Body(body_id));
 884             clean_fn_decl_legacy_const_generics(&mut func, attrs);
 885             FunctionItem(func)
 886         }
 887     }
 888 }
 889
 890 /// This is needed to make it more "readable" when documenting functions using
 891 /// `rustc_legacy_const_generics`. More information in
 892 /// <https://github.com/rust-lang/rust/issues/83167>.
 893 fn clean_fn_decl_legacy_const_generics(func: &mut Function, attrs: &[ast::Attribute]) {
 894     for meta_item_list in attrs
 895         .iter()
 896         .filter(|a| a.has_name(sym::rustc_legacy_const_generics))
 897         .filter_map(|a| a.meta_item_list())
 898     {
 899         for (pos, literal) in meta_item_list.iter().filter_map(|meta| meta.literal()).enumerate() {
 900             match literal.kind {
 901                 ast::LitKind::Int(a, _) => {
 902                     let gen = func.generics.params.remove(0);
 903                     if let GenericParamDef { name, kind: GenericParamDefKind::Const { ty, .. } } =
 904                         gen
 905                     {
 906                         func.decl
 907                             .inputs
 908                             .values
 909                             .insert(a as _, Argument { name, type_: *ty, is_const: true });
 910                     } else {
 911                         panic!("unexpected non const in position {pos}");
 912                     }
 913                 }
 914                 _ => panic!("invalid arg index"),
 915             }
 916         }
 917     }
 918 }
 919
 920 enum FunctionArgs<'tcx> {
 921     Body(hir::BodyId),
 922     Names(&'tcx [Ident]),
 923 }
 924
 925 fn clean_function<'tcx>(
 926     cx: &mut DocContext<'tcx>,
 927     sig: &hir::FnSig<'tcx>,
 928     generics: &hir::Generics<'tcx>,
 929     args: FunctionArgs<'tcx>,
 930 ) -> Box<Function> {
 931     let (generics, decl) = enter_impl_trait(cx, |cx| {
 932         // NOTE: generics must be cleaned before args
 933         let generics = clean_generics(generics, cx);
 934         let args = match args {
 935             FunctionArgs::Body(body_id) => {
 936                 clean_args_from_types_and_body_id(cx, sig.decl.inputs, body_id)
 937             }
 938             FunctionArgs::Names(names) => {
 939                 clean_args_from_types_and_names(cx, sig.decl.inputs, names)
 940             }
 941         };
 942         let mut decl = clean_fn_decl_with_args(cx, sig.decl, args);
 943         if sig.header.is_async() {
 944             decl.output = decl.sugared_async_return_type();
 945         }
 946         (generics, decl)
 947     });
 948     Box::new(Function { decl, generics })
 949 }
 950
 951 fn clean_args_from_types_and_names<'tcx>(
 952     cx: &mut DocContext<'tcx>,
 953     types: &[hir::Ty<'tcx>],
 954     names: &[Ident],
 955 ) -> Arguments {
 956     Arguments {
 957         values: types
 958             .iter()
 959             .enumerate()
 960             .map(|(i, ty)| {
 961                 let mut name = names.get(i).map_or(kw::Empty, |ident| ident.name);
 962                 if name.is_empty() {
 963                     name = kw::Underscore;
 964                 }
 965                 Argument { name, type_: clean_ty(ty, cx), is_const: false }
 966             })
 967             .collect(),
 968     }
 969 }
 970
 971 fn clean_args_from_types_and_body_id<'tcx>(
 972     cx: &mut DocContext<'tcx>,
 973     types: &[hir::Ty<'tcx>],
 974     body_id: hir::BodyId,
 975 ) -> Arguments {
 976     let body = cx.tcx.hir().body(body_id);
 977
 978     Arguments {
 979         values: types
 980             .iter()
 981             .enumerate()
 982             .map(|(i, ty)| Argument {
 983                 name: name_from_pat(body.params[i].pat),
 984                 type_: clean_ty(ty, cx),
 985                 is_const: false,
 986             })
 987             .collect(),
 988     }
 989 }
 990
 991 fn clean_fn_decl_with_args<'tcx>(
 992     cx: &mut DocContext<'tcx>,
 993     decl: &hir::FnDecl<'tcx>,
 994     args: Arguments,
 995 ) -> FnDecl {
 996     let output = match decl.output {
 997         hir::FnRetTy::Return(typ) => Return(clean_ty(typ, cx)),
 998         hir::FnRetTy::DefaultReturn(..) => DefaultReturn,
 999     };
1000     FnDecl { inputs: args, output, c_variadic: decl.c_variadic }
1001 }
1002
1003 fn clean_fn_decl_from_did_and_sig<'tcx>(
1004     cx: &mut DocContext<'tcx>,
1005     did: Option<DefId>,
1006     sig: ty::PolyFnSig<'tcx>,
1007 ) -> FnDecl {
1008     let mut names = did.map_or(&[] as &[_], |did| cx.tcx.fn_arg_names(did)).iter();
1009
1010     // We assume all empty tuples are default return type. This theoretically can discard `-> ()`,
1011     // but shouldn't change any code meaning.
1012     let output = match clean_middle_ty(sig.skip_binder().output(), cx, None) {
1013         Type::Tuple(inner) if inner.is_empty() => DefaultReturn,
1014         ty => Return(ty),
1015     };
1016
1017     FnDecl {
1018         output,
1019         c_variadic: sig.skip_binder().c_variadic,
1020         inputs: Arguments {
1021             values: sig
1022                 .skip_binder()
1023                 .inputs()
1024                 .iter()
1025                 .map(|t| Argument {
1026                     type_: clean_middle_ty(*t, cx, None),
1027                     name: names.next().map_or(kw::Empty, |i| i.name),
1028                     is_const: false,
1029                 })
1030                 .collect(),
1031         },
1032     }
1033 }
1034
1035 fn clean_trait_ref<'tcx>(trait_ref: &hir::TraitRef<'tcx>, cx: &mut DocContext<'tcx>) -> Path {
1036     let path = clean_path(trait_ref.path, cx);
1037     register_res(cx, path.res);
1038     path
1039 }
1040
1041 fn clean_poly_trait_ref<'tcx>(
1042     poly_trait_ref: &hir::PolyTraitRef<'tcx>,
1043     cx: &mut DocContext<'tcx>,
1044 ) -> PolyTrait {
1045     PolyTrait {
1046         trait_: clean_trait_ref(&poly_trait_ref.trait_ref, cx),
1047         generic_params: poly_trait_ref
1048             .bound_generic_params
1049             .iter()
1050             .filter(|p| !is_elided_lifetime(p))
1051             .map(|x| clean_generic_param(cx, None, x))
1052             .collect(),
1053     }
1054 }
1055
1056 fn clean_trait_item<'tcx>(trait_item: &hir::TraitItem<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
1057     let local_did = trait_item.owner_id.to_def_id();
1058     cx.with_param_env(local_did, |cx| {
1059         let inner = match trait_item.kind {
1060             hir::TraitItemKind::Const(ty, Some(default)) => AssocConstItem(
1061                 clean_ty(ty, cx),
1062                 ConstantKind::Local { def_id: local_did, body: default },
1063             ),
1064             hir::TraitItemKind::Const(ty, None) => TyAssocConstItem(clean_ty(ty, cx)),
1065             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
1066                 let m = clean_function(cx, sig, trait_item.generics, FunctionArgs::Body(body));
1067                 MethodItem(m, None)
1068             }
1069             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(names)) => {
1070                 let m = clean_function(cx, sig, trait_item.generics, FunctionArgs::Names(names));
1071                 TyMethodItem(m)
1072             }
1073             hir::TraitItemKind::Type(bounds, Some(default)) => {
1074                 let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
1075                 let bounds = bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect();
1076                 let item_type = clean_middle_ty(hir_ty_to_ty(cx.tcx, default), cx, None);
1077                 AssocTypeItem(
1078                     Box::new(Typedef {
1079                         type_: clean_ty(default, cx),
1080                         generics,
1081                         item_type: Some(item_type),
1082                     }),
1083                     bounds,
1084                 )
1085             }
1086             hir::TraitItemKind::Type(bounds, None) => {
1087                 let generics = enter_impl_trait(cx, |cx| clean_generics(trait_item.generics, cx));
1088                 let bounds = bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect();
1089                 TyAssocTypeItem(generics, bounds)
1090             }
1091         };
1092         Item::from_def_id_and_parts(local_did, Some(trait_item.ident.name), inner, cx)
1093     })
1094 }
1095
1096 pub(crate) fn clean_impl_item<'tcx>(
1097     impl_: &hir::ImplItem<'tcx>,
1098     cx: &mut DocContext<'tcx>,
1099 ) -> Item {
1100     let local_did = impl_.owner_id.to_def_id();
1101     cx.with_param_env(local_did, |cx| {
1102         let inner = match impl_.kind {
1103             hir::ImplItemKind::Const(ty, expr) => {
1104                 let default = ConstantKind::Local { def_id: local_did, body: expr };
1105                 AssocConstItem(clean_ty(ty, cx), default)
1106             }
1107             hir::ImplItemKind::Fn(ref sig, body) => {
1108                 let m = clean_function(cx, sig, impl_.generics, FunctionArgs::Body(body));
1109                 let defaultness = cx.tcx.impl_defaultness(impl_.owner_id);
1110                 MethodItem(m, Some(defaultness))
1111             }
1112             hir::ImplItemKind::Type(hir_ty) => {
1113                 let type_ = clean_ty(hir_ty, cx);
1114                 let generics = clean_generics(impl_.generics, cx);
1115                 let item_type = clean_middle_ty(hir_ty_to_ty(cx.tcx, hir_ty), cx, None);
1116                 AssocTypeItem(
1117                     Box::new(Typedef { type_, generics, item_type: Some(item_type) }),
1118                     Vec::new(),
1119                 )
1120             }
1121         };
1122
1123         Item::from_def_id_and_parts(local_did, Some(impl_.ident.name), inner, cx)
1124     })
1125 }
1126
1127 pub(crate) fn clean_middle_assoc_item<'tcx>(
1128     assoc_item: &ty::AssocItem,
1129     cx: &mut DocContext<'tcx>,
1130 ) -> Item {
1131     let tcx = cx.tcx;
1132     let kind = match assoc_item.kind {
1133         ty::AssocKind::Const => {
1134             let ty = clean_middle_ty(tcx.type_of(assoc_item.def_id), cx, Some(assoc_item.def_id));
1135
1136             let provided = match assoc_item.container {
1137                 ty::ImplContainer => true,
1138                 ty::TraitContainer => tcx.impl_defaultness(assoc_item.def_id).has_value(),
1139             };
1140             if provided {
1141                 AssocConstItem(ty, ConstantKind::Extern { def_id: assoc_item.def_id })
1142             } else {
1143                 TyAssocConstItem(ty)
1144             }
1145         }
1146         ty::AssocKind::Fn => {
1147             let generics = clean_ty_generics(
1148                 cx,
1149                 tcx.generics_of(assoc_item.def_id),
1150                 tcx.explicit_predicates_of(assoc_item.def_id),
1151             );
1152             let sig = tcx.fn_sig(assoc_item.def_id);
1153             let mut decl = clean_fn_decl_from_did_and_sig(cx, Some(assoc_item.def_id), sig);
1154
1155             if assoc_item.fn_has_self_parameter {
1156                 let self_ty = match assoc_item.container {
1157                     ty::ImplContainer => tcx.type_of(assoc_item.container_id(tcx)),
1158                     ty::TraitContainer => tcx.types.self_param,
1159                 };
1160                 let self_arg_ty = sig.input(0).skip_binder();
1161                 if self_arg_ty == self_ty {
1162                     decl.inputs.values[0].type_ = Generic(kw::SelfUpper);
1163                 } else if let ty::Ref(_, ty, _) = *self_arg_ty.kind() {
1164                     if ty == self_ty {
1165                         match decl.inputs.values[0].type_ {
1166                             BorrowedRef { ref mut type_, .. } => **type_ = Generic(kw::SelfUpper),
1167                             _ => unreachable!(),
1168                         }
1169                     }
1170                 }
1171             }
1172
1173             let provided = match assoc_item.container {
1174                 ty::ImplContainer => true,
1175                 ty::TraitContainer => assoc_item.defaultness(tcx).has_value(),
1176             };
1177             if provided {
1178                 let defaultness = match assoc_item.container {
1179                     ty::ImplContainer => Some(assoc_item.defaultness(tcx)),
1180                     ty::TraitContainer => None,
1181                 };
1182                 MethodItem(Box::new(Function { generics, decl }), defaultness)
1183             } else {
1184                 TyMethodItem(Box::new(Function { generics, decl }))
1185             }
1186         }
1187         ty::AssocKind::Type => {
1188             let my_name = assoc_item.name;
1189
1190             fn param_eq_arg(param: &GenericParamDef, arg: &GenericArg) -> bool {
1191                 match (&param.kind, arg) {
1192                     (GenericParamDefKind::Type { .. }, GenericArg::Type(Type::Generic(ty)))
1193                         if *ty == param.name =>
1194                     {
1195                         true
1196                     }
1197                     (GenericParamDefKind::Lifetime { .. }, GenericArg::Lifetime(Lifetime(lt)))
1198                         if *lt == param.name =>
1199                     {
1200                         true
1201                     }
1202                     (GenericParamDefKind::Const { .. }, GenericArg::Const(c)) => match &c.kind {
1203                         ConstantKind::TyConst { expr } => expr == param.name.as_str(),
1204                         _ => false,
1205                     },
1206                     _ => false,
1207                 }
1208             }
1209
1210             if let ty::TraitContainer = assoc_item.container {
1211                 let bounds = tcx.explicit_item_bounds(assoc_item.def_id);
1212                 let predicates = tcx.explicit_predicates_of(assoc_item.def_id).predicates;
1213                 let predicates =
1214                     tcx.arena.alloc_from_iter(bounds.into_iter().chain(predicates).copied());
1215                 let mut generics = clean_ty_generics(
1216                     cx,
1217                     tcx.generics_of(assoc_item.def_id),
1218                     ty::GenericPredicates { parent: None, predicates },
1219                 );
1220                 // Filter out the bounds that are (likely?) directly attached to the associated type,
1221                 // as opposed to being located in the where clause.
1222                 let mut bounds: Vec<GenericBound> = Vec::new();
1223                 generics.where_predicates.retain_mut(|pred| match *pred {
1224                     WherePredicate::BoundPredicate {
1225                         ty: QPath(box QPathData { ref assoc, ref self_type, ref trait_, .. }),
1226                         bounds: ref mut pred_bounds,
1227                         ..
1228                     } => {
1229                         if assoc.name != my_name {
1230                             return true;
1231                         }
1232                         if trait_.def_id() != assoc_item.container_id(tcx) {
1233                             return true;
1234                         }
1235                         match *self_type {
1236                             Generic(ref s) if *s == kw::SelfUpper => {}
1237                             _ => return true,
1238                         }
1239                         match &assoc.args {
1240                             GenericArgs::AngleBracketed { args, bindings } => {
1241                                 if !bindings.is_empty()
1242                                     || generics
1243                                         .params
1244                                         .iter()
1245                                         .zip(args.iter())
1246                                         .any(|(param, arg)| !param_eq_arg(param, arg))
1247                                 {
1248                                     return true;
1249                                 }
1250                             }
1251                             GenericArgs::Parenthesized { .. } => {
1252                                 // The only time this happens is if we're inside the rustdoc for Fn(),
1253                                 // which only has one associated type, which is not a GAT, so whatever.
1254                             }
1255                         }
1256                         bounds.extend(mem::replace(pred_bounds, Vec::new()));
1257                         false
1258                     }
1259                     _ => true,
1260                 });
1261                 // Our Sized/?Sized bound didn't get handled when creating the generics
1262                 // because we didn't actually get our whole set of bounds until just now
1263                 // (some of them may have come from the trait). If we do have a sized
1264                 // bound, we remove it, and if we don't then we add the `?Sized` bound
1265                 // at the end.
1266                 match bounds.iter().position(|b| b.is_sized_bound(cx)) {
1267                     Some(i) => {
1268                         bounds.remove(i);
1269                     }
1270                     None => bounds.push(GenericBound::maybe_sized(cx)),
1271                 }
1272                 // Move bounds that are (likely) directly attached to the parameters of the
1273                 // (generic) associated type from the where clause to the respective parameter.
1274                 // There is no guarantee that this is what the user actually wrote but we have
1275                 // no way of knowing.
1276                 let mut where_predicates = ThinVec::new();
1277                 for mut pred in generics.where_predicates {
1278                     if let WherePredicate::BoundPredicate { ty: Generic(arg), bounds, .. } = &mut pred
1279                     && let Some(GenericParamDef {
1280                         kind: GenericParamDefKind::Type { bounds: param_bounds, .. },
1281                         ..
1282                     }) = generics.params.iter_mut().find(|param| &param.name == arg)
1283                     {
1284                         param_bounds.extend(mem::take(bounds));
1285                     } else {
1286                         where_predicates.push(pred);
1287                     }
1288                 }
1289                 generics.where_predicates = where_predicates;
1290
1291                 if tcx.impl_defaultness(assoc_item.def_id).has_value() {
1292                     AssocTypeItem(
1293                         Box::new(Typedef {
1294                             type_: clean_middle_ty(
1295                                 tcx.type_of(assoc_item.def_id),
1296                                 cx,
1297                                 Some(assoc_item.def_id),
1298                             ),
1299                             generics,
1300                             // FIXME: should we obtain the Type from HIR and pass it on here?
1301                             item_type: None,
1302                         }),
1303                         bounds,
1304                     )
1305                 } else {
1306                     TyAssocTypeItem(generics, bounds)
1307                 }
1308             } else {
1309                 // FIXME: when could this happen? Associated items in inherent impls?
1310                 AssocTypeItem(
1311                     Box::new(Typedef {
1312                         type_: clean_middle_ty(
1313                             tcx.type_of(assoc_item.def_id),
1314                             cx,
1315                             Some(assoc_item.def_id),
1316                         ),
1317                         generics: Generics {
1318                             params: ThinVec::new(),
1319                             where_predicates: ThinVec::new(),
1320                         },
1321                         item_type: None,
1322                     }),
1323                     Vec::new(),
1324                 )
1325             }
1326         }
1327     };
1328
1329     Item::from_def_id_and_parts(assoc_item.def_id, Some(assoc_item.name), kind, cx)
1330 }
1331
1332 fn clean_qpath<'tcx>(hir_ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1333     let hir::Ty { hir_id: _, span, ref kind } = *hir_ty;
1334     let hir::TyKind::Path(qpath) = kind else { unreachable!() };
1335
1336     match qpath {
1337         hir::QPath::Resolved(None, path) => {
1338             if let Res::Def(DefKind::TyParam, did) = path.res {
1339                 if let Some(new_ty) = cx.substs.get(&did).and_then(|p| p.as_ty()).cloned() {
1340                     return new_ty;
1341                 }
1342                 if let Some(bounds) = cx.impl_trait_bounds.remove(&did.into()) {
1343                     return ImplTrait(bounds);
1344                 }
1345             }
1346
1347             if let Some(expanded) = maybe_expand_private_type_alias(cx, path) {
1348                 expanded
1349             } else {
1350                 let path = clean_path(path, cx);
1351                 resolve_type(cx, path)
1352             }
1353         }
1354         hir::QPath::Resolved(Some(qself), p) => {
1355             // Try to normalize `<X as Y>::T` to a type
1356             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1357             if let Some(normalized_value) = normalize(cx, ty) {
1358                 return clean_middle_ty(normalized_value, cx, None);
1359             }
1360
1361             let trait_segments = &p.segments[..p.segments.len() - 1];
1362             let trait_def = cx.tcx.associated_item(p.res.def_id()).container_id(cx.tcx);
1363             let trait_ = self::Path {
1364                 res: Res::Def(DefKind::Trait, trait_def),
1365                 segments: trait_segments.iter().map(|x| clean_path_segment(x, cx)).collect(),
1366             };
1367             register_res(cx, trait_.res);
1368             let self_def_id = DefId::local(qself.hir_id.owner.def_id.local_def_index);
1369             let self_type = clean_ty(qself, cx);
1370             let should_show_cast = compute_should_show_cast(Some(self_def_id), &trait_, &self_type);
1371             Type::QPath(Box::new(QPathData {
1372                 assoc: clean_path_segment(p.segments.last().expect("segments were empty"), cx),
1373                 should_show_cast,
1374                 self_type,
1375                 trait_,
1376             }))
1377         }
1378         hir::QPath::TypeRelative(qself, segment) => {
1379             let ty = hir_ty_to_ty(cx.tcx, hir_ty);
1380             let res = match ty.kind() {
1381                 ty::Projection(proj) => Res::Def(DefKind::Trait, proj.trait_ref(cx.tcx).def_id),
1382                 // Rustdoc handles `ty::Error`s by turning them into `Type::Infer`s.
1383                 ty::Error(_) => return Type::Infer,
1384                 // Otherwise, this is an inherent associated type.
1385                 _ => return clean_middle_ty(ty, cx, None),
1386             };
1387             let trait_ = clean_path(&hir::Path { span, res, segments: &[] }, cx);
1388             register_res(cx, trait_.res);
1389             let self_def_id = res.opt_def_id();
1390             let self_type = clean_ty(qself, cx);
1391             let should_show_cast = compute_should_show_cast(self_def_id, &trait_, &self_type);
1392             Type::QPath(Box::new(QPathData {
1393                 assoc: clean_path_segment(segment, cx),
1394                 should_show_cast,
1395                 self_type,
1396                 trait_,
1397             }))
1398         }
1399         hir::QPath::LangItem(..) => bug!("clean: requiring documentation of lang item"),
1400     }
1401 }
1402
1403 fn maybe_expand_private_type_alias<'tcx>(
1404     cx: &mut DocContext<'tcx>,
1405     path: &hir::Path<'tcx>,
1406 ) -> Option<Type> {
1407     let Res::Def(DefKind::TyAlias, def_id) = path.res else { return None };
1408     // Substitute private type aliases
1409     let def_id = def_id.as_local()?;
1410     let alias = if !cx.cache.effective_visibilities.is_exported(cx.tcx, def_id.to_def_id()) {
1411         &cx.tcx.hir().expect_item(def_id).kind
1412     } else {
1413         return None;
1414     };
1415     let hir::ItemKind::TyAlias(ty, generics) = alias else { return None };
1416
1417     let provided_params = &path.segments.last().expect("segments were empty");
1418     let mut substs = FxHashMap::default();
1419     let generic_args = provided_params.args();
1420
1421     let mut indices: hir::GenericParamCount = Default::default();
1422     for param in generics.params.iter() {
1423         match param.kind {
1424             hir::GenericParamKind::Lifetime { .. } => {
1425                 let mut j = 0;
1426                 let lifetime = generic_args.args.iter().find_map(|arg| match arg {
1427                     hir::GenericArg::Lifetime(lt) => {
1428                         if indices.lifetimes == j {
1429                             return Some(lt);
1430                         }
1431                         j += 1;
1432                         None
1433                     }
1434                     _ => None,
1435                 });
1436                 if let Some(lt) = lifetime {
1437                     let lt_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1438                     let cleaned =
1439                         if !lt.is_elided() { clean_lifetime(lt, cx) } else { Lifetime::elided() };
1440                     substs.insert(lt_def_id.to_def_id(), SubstParam::Lifetime(cleaned));
1441                 }
1442                 indices.lifetimes += 1;
1443             }
1444             hir::GenericParamKind::Type { ref default, .. } => {
1445                 let ty_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1446                 let mut j = 0;
1447                 let type_ = generic_args.args.iter().find_map(|arg| match arg {
1448                     hir::GenericArg::Type(ty) => {
1449                         if indices.types == j {
1450                             return Some(ty);
1451                         }
1452                         j += 1;
1453                         None
1454                     }
1455                     _ => None,
1456                 });
1457                 if let Some(ty) = type_ {
1458                     substs.insert(ty_param_def_id.to_def_id(), SubstParam::Type(clean_ty(ty, cx)));
1459                 } else if let Some(default) = *default {
1460                     substs.insert(
1461                         ty_param_def_id.to_def_id(),
1462                         SubstParam::Type(clean_ty(default, cx)),
1463                     );
1464                 }
1465                 indices.types += 1;
1466             }
1467             hir::GenericParamKind::Const { .. } => {
1468                 let const_param_def_id = cx.tcx.hir().local_def_id(param.hir_id);
1469                 let mut j = 0;
1470                 let const_ = generic_args.args.iter().find_map(|arg| match arg {
1471                     hir::GenericArg::Const(ct) => {
1472                         if indices.consts == j {
1473                             return Some(ct);
1474                         }
1475                         j += 1;
1476                         None
1477                     }
1478                     _ => None,
1479                 });
1480                 if let Some(ct) = const_ {
1481                     substs.insert(
1482                         const_param_def_id.to_def_id(),
1483                         SubstParam::Constant(clean_const(ct, cx)),
1484                     );
1485                 }
1486                 // FIXME(const_generics_defaults)
1487                 indices.consts += 1;
1488             }
1489         }
1490     }
1491
1492     Some(cx.enter_alias(substs, |cx| clean_ty(ty, cx)))
1493 }
1494
1495 pub(crate) fn clean_ty<'tcx>(ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> Type {
1496     use rustc_hir::*;
1497
1498     match ty.kind {
1499         TyKind::Never => Primitive(PrimitiveType::Never),
1500         TyKind::Ptr(ref m) => RawPointer(m.mutbl, Box::new(clean_ty(m.ty, cx))),
1501         TyKind::Rptr(ref l, ref m) => {
1502             // There are two times a `Fresh` lifetime can be created:
1503             // 1. For `&'_ x`, written by the user. This corresponds to `lower_lifetime` in `rustc_ast_lowering`.
1504             // 2. For `&x` as a parameter to an `async fn`. This corresponds to `elided_ref_lifetime in `rustc_ast_lowering`.
1505             //    See #59286 for more information.
1506             // Ideally we would only hide the `'_` for case 2., but I don't know a way to distinguish it.
1507             // Turning `fn f(&'_ self)` into `fn f(&self)` isn't the worst thing in the world, though;
1508             // there's no case where it could cause the function to fail to compile.
1509             let elided =
1510                 l.is_elided() || matches!(l.name, LifetimeName::Param(_, ParamName::Fresh));
1511             let lifetime = if elided { None } else { Some(clean_lifetime(*l, cx)) };
1512             BorrowedRef { lifetime, mutability: m.mutbl, type_: Box::new(clean_ty(m.ty, cx)) }
1513         }
1514         TyKind::Slice(ty) => Slice(Box::new(clean_ty(ty, cx))),
1515         TyKind::Array(ty, ref length) => {
1516             let length = match length {
1517                 hir::ArrayLen::Infer(_, _) => "_".to_string(),
1518                 hir::ArrayLen::Body(anon_const) => {
1519                     let def_id = cx.tcx.hir().local_def_id(anon_const.hir_id);
1520                     // NOTE(min_const_generics): We can't use `const_eval_poly` for constants
1521                     // as we currently do not supply the parent generics to anonymous constants
1522                     // but do allow `ConstKind::Param`.
1523                     //
1524                     // `const_eval_poly` tries to first substitute generic parameters which
1525                     // results in an ICE while manually constructing the constant and using `eval`
1526                     // does nothing for `ConstKind::Param`.
1527                     let ct = ty::Const::from_anon_const(cx.tcx, def_id);
1528                     let param_env = cx.tcx.param_env(def_id);
1529                     print_const(cx, ct.eval(cx.tcx, param_env))
1530                 }
1531             };
1532
1533             Array(Box::new(clean_ty(ty, cx)), length)
1534         }
1535         TyKind::Tup(tys) => Tuple(tys.iter().map(|ty| clean_ty(ty, cx)).collect()),
1536         TyKind::OpaqueDef(item_id, _, _) => {
1537             let item = cx.tcx.hir().item(item_id);
1538             if let hir::ItemKind::OpaqueTy(ref ty) = item.kind {
1539                 ImplTrait(ty.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect())
1540             } else {
1541                 unreachable!()
1542             }
1543         }
1544         TyKind::Path(_) => clean_qpath(ty, cx),
1545         TyKind::TraitObject(bounds, ref lifetime, _) => {
1546             let bounds = bounds.iter().map(|bound| clean_poly_trait_ref(bound, cx)).collect();
1547             let lifetime =
1548                 if !lifetime.is_elided() { Some(clean_lifetime(*lifetime, cx)) } else { None };
1549             DynTrait(bounds, lifetime)
1550         }
1551         TyKind::BareFn(barefn) => BareFunction(Box::new(clean_bare_fn_ty(barefn, cx))),
1552         // Rustdoc handles `TyKind::Err`s by turning them into `Type::Infer`s.
1553         TyKind::Infer | TyKind::Err | TyKind::Typeof(..) => Infer,
1554     }
1555 }
1556
1557 /// Returns `None` if the type could not be normalized
1558 fn normalize<'tcx>(cx: &mut DocContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
1559     // HACK: low-churn fix for #79459 while we wait for a trait normalization fix
1560     if !cx.tcx.sess.opts.unstable_opts.normalize_docs {
1561         return None;
1562     }
1563
1564     use crate::rustc_trait_selection::infer::TyCtxtInferExt;
1565     use crate::rustc_trait_selection::traits::query::normalize::AtExt;
1566     use rustc_middle::traits::ObligationCause;
1567
1568     // Try to normalize `<X as Y>::T` to a type
1569     let infcx = cx.tcx.infer_ctxt().build();
1570     let normalized = infcx
1571         .at(&ObligationCause::dummy(), cx.param_env)
1572         .normalize(ty)
1573         .map(|resolved| infcx.resolve_vars_if_possible(resolved.value));
1574     match normalized {
1575         Ok(normalized_value) => {
1576             debug!("normalized {:?} to {:?}", ty, normalized_value);
1577             Some(normalized_value)
1578         }
1579         Err(err) => {
1580             debug!("failed to normalize {:?}: {:?}", ty, err);
1581             None
1582         }
1583     }
1584 }
1585
1586 pub(crate) fn clean_middle_ty<'tcx>(
1587     ty: Ty<'tcx>,
1588     cx: &mut DocContext<'tcx>,
1589     def_id: Option<DefId>,
1590 ) -> Type {
1591     trace!("cleaning type: {:?}", ty);
1592     let ty = normalize(cx, ty).unwrap_or(ty);
1593     match *ty.kind() {
1594         ty::Never => Primitive(PrimitiveType::Never),
1595         ty::Bool => Primitive(PrimitiveType::Bool),
1596         ty::Char => Primitive(PrimitiveType::Char),
1597         ty::Int(int_ty) => Primitive(int_ty.into()),
1598         ty::Uint(uint_ty) => Primitive(uint_ty.into()),
1599         ty::Float(float_ty) => Primitive(float_ty.into()),
1600         ty::Str => Primitive(PrimitiveType::Str),
1601         ty::Slice(ty) => Slice(Box::new(clean_middle_ty(ty, cx, None))),
1602         ty::Array(ty, mut n) => {
1603             n = n.eval(cx.tcx, ty::ParamEnv::reveal_all());
1604             let n = print_const(cx, n);
1605             Array(Box::new(clean_middle_ty(ty, cx, None)), n)
1606         }
1607         ty::RawPtr(mt) => RawPointer(mt.mutbl, Box::new(clean_middle_ty(mt.ty, cx, None))),
1608         ty::Ref(r, ty, mutbl) => BorrowedRef {
1609             lifetime: clean_middle_region(r),
1610             mutability: mutbl,
1611             type_: Box::new(clean_middle_ty(ty, cx, None)),
1612         },
1613         ty::FnDef(..) | ty::FnPtr(_) => {
1614             let sig = ty.fn_sig(cx.tcx);
1615             let decl = clean_fn_decl_from_did_and_sig(cx, None, sig);
1616             BareFunction(Box::new(BareFunctionDecl {
1617                 unsafety: sig.unsafety(),
1618                 generic_params: Vec::new(),
1619                 decl,
1620                 abi: sig.abi(),
1621             }))
1622         }
1623         ty::Adt(def, substs) => {
1624             let did = def.did();
1625             let kind = match def.adt_kind() {
1626                 AdtKind::Struct => ItemType::Struct,
1627                 AdtKind::Union => ItemType::Union,
1628                 AdtKind::Enum => ItemType::Enum,
1629             };
1630             inline::record_extern_fqn(cx, did, kind);
1631             let path = external_path(cx, did, false, ThinVec::new(), substs);
1632             Type::Path { path }
1633         }
1634         ty::Foreign(did) => {
1635             inline::record_extern_fqn(cx, did, ItemType::ForeignType);
1636             let path = external_path(cx, did, false, ThinVec::new(), InternalSubsts::empty());
1637             Type::Path { path }
1638         }
1639         ty::Dynamic(obj, ref reg, _) => {
1640             // HACK: pick the first `did` as the `did` of the trait object. Someone
1641             // might want to implement "native" support for marker-trait-only
1642             // trait objects.
1643             let mut dids = obj.auto_traits();
1644             let did = obj
1645                 .principal_def_id()
1646                 .or_else(|| dids.next())
1647                 .unwrap_or_else(|| panic!("found trait object `{:?}` with no traits?", ty));
1648             let substs = match obj.principal() {
1649                 Some(principal) => principal.skip_binder().substs,
1650                 // marker traits have no substs.
1651                 _ => cx.tcx.intern_substs(&[]),
1652             };
1653
1654             inline::record_extern_fqn(cx, did, ItemType::Trait);
1655
1656             let lifetime = clean_middle_region(*reg);
1657             let mut bounds = dids
1658                 .map(|did| {
1659                     let empty = cx.tcx.intern_substs(&[]);
1660                     let path = external_path(cx, did, false, ThinVec::new(), empty);
1661                     inline::record_extern_fqn(cx, did, ItemType::Trait);
1662                     PolyTrait { trait_: path, generic_params: Vec::new() }
1663                 })
1664                 .collect::<Vec<_>>();
1665
1666             let bindings = obj
1667                 .projection_bounds()
1668                 .map(|pb| TypeBinding {
1669                     assoc: projection_to_path_segment(
1670                         pb.skip_binder()
1671                             // HACK(compiler-errors): Doesn't actually matter what self
1672                             // type we put here, because we're only using the GAT's substs.
1673                             .with_self_ty(cx.tcx, cx.tcx.types.self_param)
1674                             .projection_ty,
1675                         cx,
1676                     ),
1677                     kind: TypeBindingKind::Equality {
1678                         term: clean_middle_term(pb.skip_binder().term, cx),
1679                     },
1680                 })
1681                 .collect();
1682
1683             let path = external_path(cx, did, false, bindings, substs);
1684             bounds.insert(0, PolyTrait { trait_: path, generic_params: Vec::new() });
1685
1686             DynTrait(bounds, lifetime)
1687         }
1688         ty::Tuple(t) => Tuple(t.iter().map(|t| clean_middle_ty(t, cx, None)).collect()),
1689
1690         ty::Projection(ref data) => clean_projection(*data, cx, def_id),
1691
1692         ty::Param(ref p) => {
1693             if let Some(bounds) = cx.impl_trait_bounds.remove(&p.index.into()) {
1694                 ImplTrait(bounds)
1695             } else {
1696                 Generic(p.name)
1697             }
1698         }
1699
1700         ty::Opaque(def_id, substs) => {
1701             // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1702             // by looking up the bounds associated with the def_id.
1703             let bounds = cx
1704                 .tcx
1705                 .explicit_item_bounds(def_id)
1706                 .iter()
1707                 .map(|(bound, _)| EarlyBinder(*bound).subst(cx.tcx, substs))
1708                 .collect::<Vec<_>>();
1709             clean_middle_opaque_bounds(cx, bounds)
1710         }
1711
1712         ty::Closure(..) => panic!("Closure"),
1713         ty::Generator(..) => panic!("Generator"),
1714         ty::Bound(..) => panic!("Bound"),
1715         ty::Placeholder(..) => panic!("Placeholder"),
1716         ty::GeneratorWitness(..) => panic!("GeneratorWitness"),
1717         ty::Infer(..) => panic!("Infer"),
1718         ty::Error(_) => panic!("Error"),
1719     }
1720 }
1721
1722 fn clean_middle_opaque_bounds<'tcx>(
1723     cx: &mut DocContext<'tcx>,
1724     bounds: Vec<ty::Predicate<'tcx>>,
1725 ) -> Type {
1726     let mut regions = vec![];
1727     let mut has_sized = false;
1728     let mut bounds = bounds
1729         .iter()
1730         .filter_map(|bound| {
1731             let bound_predicate = bound.kind();
1732             let trait_ref = match bound_predicate.skip_binder() {
1733                 ty::PredicateKind::Trait(tr) => bound_predicate.rebind(tr.trait_ref),
1734                 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_ty, reg)) => {
1735                     if let Some(r) = clean_middle_region(reg) {
1736                         regions.push(GenericBound::Outlives(r));
1737                     }
1738                     return None;
1739                 }
1740                 _ => return None,
1741             };
1742
1743             if let Some(sized) = cx.tcx.lang_items().sized_trait() {
1744                 if trait_ref.def_id() == sized {
1745                     has_sized = true;
1746                     return None;
1747                 }
1748             }
1749
1750             let bindings: ThinVec<_> = bounds
1751                 .iter()
1752                 .filter_map(|bound| {
1753                     if let ty::PredicateKind::Projection(proj) = bound.kind().skip_binder() {
1754                         if proj.projection_ty.trait_ref(cx.tcx) == trait_ref.skip_binder() {
1755                             Some(TypeBinding {
1756                                 assoc: projection_to_path_segment(proj.projection_ty, cx),
1757                                 kind: TypeBindingKind::Equality {
1758                                     term: clean_middle_term(proj.term, cx),
1759                                 },
1760                             })
1761                         } else {
1762                             None
1763                         }
1764                     } else {
1765                         None
1766                     }
1767                 })
1768                 .collect();
1769
1770             Some(clean_poly_trait_ref_with_bindings(cx, trait_ref, bindings))
1771         })
1772         .collect::<Vec<_>>();
1773     bounds.extend(regions);
1774     if !has_sized && !bounds.is_empty() {
1775         bounds.insert(0, GenericBound::maybe_sized(cx));
1776     }
1777     ImplTrait(bounds)
1778 }
1779
1780 pub(crate) fn clean_field<'tcx>(field: &hir::FieldDef<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
1781     let def_id = cx.tcx.hir().local_def_id(field.hir_id).to_def_id();
1782     clean_field_with_def_id(def_id, field.ident.name, clean_ty(field.ty, cx), cx)
1783 }
1784
1785 pub(crate) fn clean_middle_field<'tcx>(field: &ty::FieldDef, cx: &mut DocContext<'tcx>) -> Item {
1786     clean_field_with_def_id(
1787         field.did,
1788         field.name,
1789         clean_middle_ty(cx.tcx.type_of(field.did), cx, Some(field.did)),
1790         cx,
1791     )
1792 }
1793
1794 pub(crate) fn clean_field_with_def_id(
1795     def_id: DefId,
1796     name: Symbol,
1797     ty: Type,
1798     cx: &mut DocContext<'_>,
1799 ) -> Item {
1800     Item::from_def_id_and_parts(def_id, Some(name), StructFieldItem(ty), cx)
1801 }
1802
1803 pub(crate) fn clean_variant_def<'tcx>(variant: &ty::VariantDef, cx: &mut DocContext<'tcx>) -> Item {
1804     let kind = match variant.ctor_kind {
1805         CtorKind::Const => Variant::CLike(match variant.discr {
1806             ty::VariantDiscr::Explicit(def_id) => Some(Discriminant { expr: None, value: def_id }),
1807             ty::VariantDiscr::Relative(_) => None,
1808         }),
1809         CtorKind::Fn => Variant::Tuple(
1810             variant.fields.iter().map(|field| clean_middle_field(field, cx)).collect(),
1811         ),
1812         CtorKind::Fictive => Variant::Struct(VariantStruct {
1813             struct_type: CtorKind::Fictive,
1814             fields: variant.fields.iter().map(|field| clean_middle_field(field, cx)).collect(),
1815         }),
1816     };
1817     Item::from_def_id_and_parts(variant.def_id, Some(variant.name), VariantItem(kind), cx)
1818 }
1819
1820 fn clean_variant_data<'tcx>(
1821     variant: &hir::VariantData<'tcx>,
1822     disr_expr: &Option<hir::AnonConst>,
1823     cx: &mut DocContext<'tcx>,
1824 ) -> Variant {
1825     match variant {
1826         hir::VariantData::Struct(..) => Variant::Struct(VariantStruct {
1827             struct_type: CtorKind::from_hir(variant),
1828             fields: variant.fields().iter().map(|x| clean_field(x, cx)).collect(),
1829         }),
1830         hir::VariantData::Tuple(..) => {
1831             Variant::Tuple(variant.fields().iter().map(|x| clean_field(x, cx)).collect())
1832         }
1833         hir::VariantData::Unit(..) => Variant::CLike(disr_expr.map(|disr| Discriminant {
1834             expr: Some(disr.body),
1835             value: cx.tcx.hir().local_def_id(disr.hir_id).to_def_id(),
1836         })),
1837     }
1838 }
1839
1840 fn clean_path<'tcx>(path: &hir::Path<'tcx>, cx: &mut DocContext<'tcx>) -> Path {
1841     Path {
1842         res: path.res,
1843         segments: path.segments.iter().map(|x| clean_path_segment(x, cx)).collect(),
1844     }
1845 }
1846
1847 fn clean_generic_args<'tcx>(
1848     generic_args: &hir::GenericArgs<'tcx>,
1849     cx: &mut DocContext<'tcx>,
1850 ) -> GenericArgs {
1851     if generic_args.parenthesized {
1852         let output = clean_ty(generic_args.bindings[0].ty(), cx);
1853         let output = if output != Type::Tuple(Vec::new()) { Some(Box::new(output)) } else { None };
1854         let inputs =
1855             generic_args.inputs().iter().map(|x| clean_ty(x, cx)).collect::<Vec<_>>().into();
1856         GenericArgs::Parenthesized { inputs, output }
1857     } else {
1858         let args = generic_args
1859             .args
1860             .iter()
1861             .map(|arg| match arg {
1862                 hir::GenericArg::Lifetime(lt) if !lt.is_elided() => {
1863                     GenericArg::Lifetime(clean_lifetime(*lt, cx))
1864                 }
1865                 hir::GenericArg::Lifetime(_) => GenericArg::Lifetime(Lifetime::elided()),
1866                 hir::GenericArg::Type(ty) => GenericArg::Type(clean_ty(ty, cx)),
1867                 hir::GenericArg::Const(ct) => GenericArg::Const(Box::new(clean_const(ct, cx))),
1868                 hir::GenericArg::Infer(_inf) => GenericArg::Infer,
1869             })
1870             .collect::<Vec<_>>()
1871             .into();
1872         let bindings =
1873             generic_args.bindings.iter().map(|x| clean_type_binding(x, cx)).collect::<ThinVec<_>>();
1874         GenericArgs::AngleBracketed { args, bindings }
1875     }
1876 }
1877
1878 fn clean_path_segment<'tcx>(
1879     path: &hir::PathSegment<'tcx>,
1880     cx: &mut DocContext<'tcx>,
1881 ) -> PathSegment {
1882     PathSegment { name: path.ident.name, args: clean_generic_args(path.args(), cx) }
1883 }
1884
1885 fn clean_bare_fn_ty<'tcx>(
1886     bare_fn: &hir::BareFnTy<'tcx>,
1887     cx: &mut DocContext<'tcx>,
1888 ) -> BareFunctionDecl {
1889     let (generic_params, decl) = enter_impl_trait(cx, |cx| {
1890         // NOTE: generics must be cleaned before args
1891         let generic_params = bare_fn
1892             .generic_params
1893             .iter()
1894             .filter(|p| !is_elided_lifetime(p))
1895             .map(|x| clean_generic_param(cx, None, x))
1896             .collect();
1897         let args = clean_args_from_types_and_names(cx, bare_fn.decl.inputs, bare_fn.param_names);
1898         let decl = clean_fn_decl_with_args(cx, bare_fn.decl, args);
1899         (generic_params, decl)
1900     });
1901     BareFunctionDecl { unsafety: bare_fn.unsafety, abi: bare_fn.abi, decl, generic_params }
1902 }
1903
1904 fn clean_maybe_renamed_item<'tcx>(
1905     cx: &mut DocContext<'tcx>,
1906     item: &hir::Item<'tcx>,
1907     renamed: Option<Symbol>,
1908     import_id: Option<hir::HirId>,
1909 ) -> Vec<Item> {
1910     use hir::ItemKind;
1911
1912     let def_id = item.owner_id.to_def_id();
1913     let mut name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
1914     cx.with_param_env(def_id, |cx| {
1915         let kind = match item.kind {
1916             ItemKind::Static(ty, mutability, body_id) => {
1917                 StaticItem(Static { type_: clean_ty(ty, cx), mutability, expr: Some(body_id) })
1918             }
1919             ItemKind::Const(ty, body_id) => ConstantItem(Constant {
1920                 type_: clean_ty(ty, cx),
1921                 kind: ConstantKind::Local { body: body_id, def_id },
1922             }),
1923             ItemKind::OpaqueTy(ref ty) => OpaqueTyItem(OpaqueTy {
1924                 bounds: ty.bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
1925                 generics: clean_generics(ty.generics, cx),
1926             }),
1927             ItemKind::TyAlias(hir_ty, generics) => {
1928                 let rustdoc_ty = clean_ty(hir_ty, cx);
1929                 let ty = clean_middle_ty(hir_ty_to_ty(cx.tcx, hir_ty), cx, None);
1930                 TypedefItem(Box::new(Typedef {
1931                     type_: rustdoc_ty,
1932                     generics: clean_generics(generics, cx),
1933                     item_type: Some(ty),
1934                 }))
1935             }
1936             ItemKind::Enum(ref def, generics) => EnumItem(Enum {
1937                 variants: def.variants.iter().map(|v| clean_variant(v, cx)).collect(),
1938                 generics: clean_generics(generics, cx),
1939             }),
1940             ItemKind::TraitAlias(generics, bounds) => TraitAliasItem(TraitAlias {
1941                 generics: clean_generics(generics, cx),
1942                 bounds: bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
1943             }),
1944             ItemKind::Union(ref variant_data, generics) => UnionItem(Union {
1945                 generics: clean_generics(generics, cx),
1946                 fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
1947             }),
1948             ItemKind::Struct(ref variant_data, generics) => StructItem(Struct {
1949                 struct_type: CtorKind::from_hir(variant_data),
1950                 generics: clean_generics(generics, cx),
1951                 fields: variant_data.fields().iter().map(|x| clean_field(x, cx)).collect(),
1952             }),
1953             ItemKind::Impl(impl_) => return clean_impl(impl_, item.hir_id(), cx),
1954             // proc macros can have a name set by attributes
1955             ItemKind::Fn(ref sig, generics, body_id) => {
1956                 clean_fn_or_proc_macro(item, sig, generics, body_id, &mut name, cx)
1957             }
1958             ItemKind::Macro(ref macro_def, _) => {
1959                 let ty_vis = cx.tcx.visibility(def_id);
1960                 MacroItem(Macro {
1961                     source: display_macro_source(cx, name, macro_def, def_id, ty_vis),
1962                 })
1963             }
1964             ItemKind::Trait(_, _, generics, bounds, item_ids) => {
1965                 let items = item_ids
1966                     .iter()
1967                     .map(|ti| clean_trait_item(cx.tcx.hir().trait_item(ti.id), cx))
1968                     .collect();
1969
1970                 TraitItem(Box::new(Trait {
1971                     def_id,
1972                     items,
1973                     generics: clean_generics(generics, cx),
1974                     bounds: bounds.iter().filter_map(|x| clean_generic_bound(x, cx)).collect(),
1975                 }))
1976             }
1977             ItemKind::ExternCrate(orig_name) => {
1978                 return clean_extern_crate(item, name, orig_name, cx);
1979             }
1980             ItemKind::Use(path, kind) => {
1981                 return clean_use_statement(item, name, path, kind, cx, &mut FxHashSet::default());
1982             }
1983             _ => unreachable!("not yet converted"),
1984         };
1985         if let Some(import_id) = import_id {
1986             let (attrs, cfg) = inline::merge_attrs(
1987                 cx,
1988                 Some(cx.tcx.parent_module(import_id).to_def_id()),
1989                 inline::load_attrs(cx, def_id),
1990                 Some(inline::load_attrs(cx, cx.tcx.hir().local_def_id(import_id).to_def_id())),
1991             );
1992             vec![Item::from_def_id_and_attrs_and_parts(
1993                 def_id,
1994                 Some(name),
1995                 kind,
1996                 Box::new(attrs),
1997                 cfg,
1998             )]
1999         } else {
2000             vec![Item::from_def_id_and_parts(def_id, Some(name), kind, cx)]
2001         }
2002     })
2003 }
2004
2005 fn clean_variant<'tcx>(variant: &hir::Variant<'tcx>, cx: &mut DocContext<'tcx>) -> Item {
2006     let kind = VariantItem(clean_variant_data(&variant.data, &variant.disr_expr, cx));
2007     Item::from_hir_id_and_parts(variant.id, Some(variant.ident.name), kind, cx)
2008 }
2009
2010 fn clean_impl<'tcx>(
2011     impl_: &hir::Impl<'tcx>,
2012     hir_id: hir::HirId,
2013     cx: &mut DocContext<'tcx>,
2014 ) -> Vec<Item> {
2015     let tcx = cx.tcx;
2016     let mut ret = Vec::new();
2017     let trait_ = impl_.of_trait.as_ref().map(|t| clean_trait_ref(t, cx));
2018     let items = impl_
2019         .items
2020         .iter()
2021         .map(|ii| clean_impl_item(tcx.hir().impl_item(ii.id), cx))
2022         .collect::<Vec<_>>();
2023     let def_id = tcx.hir().local_def_id(hir_id);
2024
2025     // If this impl block is an implementation of the Deref trait, then we
2026     // need to try inlining the target's inherent impl blocks as well.
2027     if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
2028         build_deref_target_impls(cx, &items, &mut ret);
2029     }
2030
2031     let for_ = clean_ty(impl_.self_ty, cx);
2032     let type_alias = for_.def_id(&cx.cache).and_then(|did| match tcx.def_kind(did) {
2033         DefKind::TyAlias => Some(clean_middle_ty(tcx.type_of(did), cx, Some(did))),
2034         _ => None,
2035     });
2036     let mut make_item = |trait_: Option<Path>, for_: Type, items: Vec<Item>| {
2037         let kind = ImplItem(Box::new(Impl {
2038             unsafety: impl_.unsafety,
2039             generics: clean_generics(impl_.generics, cx),
2040             trait_,
2041             for_,
2042             items,
2043             polarity: tcx.impl_polarity(def_id),
2044             kind: if utils::has_doc_flag(tcx, def_id.to_def_id(), sym::fake_variadic) {
2045                 ImplKind::FakeVaradic
2046             } else {
2047                 ImplKind::Normal
2048             },
2049         }));
2050         Item::from_hir_id_and_parts(hir_id, None, kind, cx)
2051     };
2052     if let Some(type_alias) = type_alias {
2053         ret.push(make_item(trait_.clone(), type_alias, items.clone()));
2054     }
2055     ret.push(make_item(trait_, for_, items));
2056     ret
2057 }
2058
2059 fn clean_extern_crate<'tcx>(
2060     krate: &hir::Item<'tcx>,
2061     name: Symbol,
2062     orig_name: Option<Symbol>,
2063     cx: &mut DocContext<'tcx>,
2064 ) -> Vec<Item> {
2065     // this is the ID of the `extern crate` statement
2066     let cnum = cx.tcx.extern_mod_stmt_cnum(krate.owner_id.def_id).unwrap_or(LOCAL_CRATE);
2067     // this is the ID of the crate itself
2068     let crate_def_id = cnum.as_def_id();
2069     let attrs = cx.tcx.hir().attrs(krate.hir_id());
2070     let ty_vis = cx.tcx.visibility(krate.owner_id);
2071     let please_inline = ty_vis.is_public()
2072         && attrs.iter().any(|a| {
2073             a.has_name(sym::doc)
2074                 && match a.meta_item_list() {
2075                     Some(l) => attr::list_contains_name(&l, sym::inline),
2076                     None => false,
2077                 }
2078         });
2079
2080     let krate_owner_def_id = krate.owner_id.to_def_id();
2081     if please_inline {
2082         let mut visited = FxHashSet::default();
2083
2084         let res = Res::Def(DefKind::Mod, crate_def_id);
2085
2086         if let Some(items) = inline::try_inline(
2087             cx,
2088             cx.tcx.parent_module(krate.hir_id()).to_def_id(),
2089             Some(krate_owner_def_id),
2090             res,
2091             name,
2092             Some(attrs),
2093             &mut visited,
2094         ) {
2095             return items;
2096         }
2097     }
2098
2099     // FIXME: using `from_def_id_and_kind` breaks `rustdoc/masked` for some reason
2100     vec![Item {
2101         name: Some(name),
2102         attrs: Box::new(Attributes::from_ast(attrs)),
2103         item_id: crate_def_id.into(),
2104         kind: Box::new(ExternCrateItem { src: orig_name }),
2105         cfg: attrs.cfg(cx.tcx, &cx.cache.hidden_cfg),
2106         inline_stmt_id: Some(krate_owner_def_id),
2107     }]
2108 }
2109
2110 fn clean_use_statement<'tcx>(
2111     import: &hir::Item<'tcx>,
2112     name: Symbol,
2113     path: &hir::Path<'tcx>,
2114     kind: hir::UseKind,
2115     cx: &mut DocContext<'tcx>,
2116     inlined_names: &mut FxHashSet<(ItemType, Symbol)>,
2117 ) -> Vec<Item> {
2118     // We need this comparison because some imports (for std types for example)
2119     // are "inserted" as well but directly by the compiler and they should not be
2120     // taken into account.
2121     if import.span.ctxt().outer_expn_data().kind == ExpnKind::AstPass(AstPass::StdImports) {
2122         return Vec::new();
2123     }
2124
2125     let visibility = cx.tcx.visibility(import.owner_id);
2126     let attrs = cx.tcx.hir().attrs(import.hir_id());
2127     let inline_attr = attrs.lists(sym::doc).get_word_attr(sym::inline);
2128     let pub_underscore = visibility.is_public() && name == kw::Underscore;
2129     let current_mod = cx.tcx.parent_module_from_def_id(import.owner_id.def_id);
2130
2131     // The parent of the module in which this import resides. This
2132     // is the same as `current_mod` if that's already the top
2133     // level module.
2134     let parent_mod = cx.tcx.parent_module_from_def_id(current_mod);
2135
2136     // This checks if the import can be seen from a higher level module.
2137     // In other words, it checks if the visibility is the equivalent of
2138     // `pub(super)` or higher. If the current module is the top level
2139     // module, there isn't really a parent module, which makes the results
2140     // meaningless. In this case, we make sure the answer is `false`.
2141     let is_visible_from_parent_mod =
2142         visibility.is_accessible_from(parent_mod, cx.tcx) && !current_mod.is_top_level_module();
2143
2144     if pub_underscore {
2145         if let Some(ref inline) = inline_attr {
2146             rustc_errors::struct_span_err!(
2147                 cx.tcx.sess,
2148                 inline.span(),
2149                 E0780,
2150                 "anonymous imports cannot be inlined"
2151             )
2152             .span_label(import.span, "anonymous import")
2153             .emit();
2154         }
2155     }
2156
2157     // We consider inlining the documentation of `pub use` statements, but we
2158     // forcefully don't inline if this is not public or if the
2159     // #[doc(no_inline)] attribute is present.
2160     // Don't inline doc(hidden) imports so they can be stripped at a later stage.
2161     let mut denied = cx.output_format.is_json()
2162         || !(visibility.is_public()
2163             || (cx.render_options.document_private && is_visible_from_parent_mod))
2164         || pub_underscore
2165         || attrs.iter().any(|a| {
2166             a.has_name(sym::doc)
2167                 && match a.meta_item_list() {
2168                     Some(l) => {
2169                         attr::list_contains_name(&l, sym::no_inline)
2170                             || attr::list_contains_name(&l, sym::hidden)
2171                     }
2172                     None => false,
2173                 }
2174         });
2175
2176     // Also check whether imports were asked to be inlined, in case we're trying to re-export a
2177     // crate in Rust 2018+
2178     let path = clean_path(path, cx);
2179     let inner = if kind == hir::UseKind::Glob {
2180         if !denied {
2181             let mut visited = FxHashSet::default();
2182             if let Some(items) = inline::try_inline_glob(cx, path.res, &mut visited, inlined_names)
2183             {
2184                 return items;
2185             }
2186         }
2187         Import::new_glob(resolve_use_source(cx, path), true)
2188     } else {
2189         if inline_attr.is_none() {
2190             if let Res::Def(DefKind::Mod, did) = path.res {
2191                 if !did.is_local() && did.is_crate_root() {
2192                     // if we're `pub use`ing an extern crate root, don't inline it unless we
2193                     // were specifically asked for it
2194                     denied = true;
2195                 }
2196             }
2197         }
2198         if !denied {
2199             let mut visited = FxHashSet::default();
2200             let import_def_id = import.owner_id.to_def_id();
2201
2202             if let Some(mut items) = inline::try_inline(
2203                 cx,
2204                 cx.tcx.parent_module(import.hir_id()).to_def_id(),
2205                 Some(import_def_id),
2206                 path.res,
2207                 name,
2208                 Some(attrs),
2209                 &mut visited,
2210             ) {
2211                 items.push(Item::from_def_id_and_parts(
2212                     import_def_id,
2213                     None,
2214                     ImportItem(Import::new_simple(name, resolve_use_source(cx, path), false)),
2215                     cx,
2216                 ));
2217                 return items;
2218             }
2219         }
2220         Import::new_simple(name, resolve_use_source(cx, path), true)
2221     };
2222
2223     vec![Item::from_def_id_and_parts(import.owner_id.to_def_id(), None, ImportItem(inner), cx)]
2224 }
2225
2226 fn clean_maybe_renamed_foreign_item<'tcx>(
2227     cx: &mut DocContext<'tcx>,
2228     item: &hir::ForeignItem<'tcx>,
2229     renamed: Option<Symbol>,
2230 ) -> Item {
2231     let def_id = item.owner_id.to_def_id();
2232     cx.with_param_env(def_id, |cx| {
2233         let kind = match item.kind {
2234             hir::ForeignItemKind::Fn(decl, names, generics) => {
2235                 let (generics, decl) = enter_impl_trait(cx, |cx| {
2236                     // NOTE: generics must be cleaned before args
2237                     let generics = clean_generics(generics, cx);
2238                     let args = clean_args_from_types_and_names(cx, decl.inputs, names);
2239                     let decl = clean_fn_decl_with_args(cx, decl, args);
2240                     (generics, decl)
2241                 });
2242                 ForeignFunctionItem(Box::new(Function { decl, generics }))
2243             }
2244             hir::ForeignItemKind::Static(ty, mutability) => {
2245                 ForeignStaticItem(Static { type_: clean_ty(ty, cx), mutability, expr: None })
2246             }
2247             hir::ForeignItemKind::Type => ForeignTypeItem,
2248         };
2249
2250         Item::from_hir_id_and_parts(
2251             item.hir_id(),
2252             Some(renamed.unwrap_or(item.ident.name)),
2253             kind,
2254             cx,
2255         )
2256     })
2257 }
2258
2259 fn clean_type_binding<'tcx>(
2260     type_binding: &hir::TypeBinding<'tcx>,
2261     cx: &mut DocContext<'tcx>,
2262 ) -> TypeBinding {
2263     TypeBinding {
2264         assoc: PathSegment {
2265             name: type_binding.ident.name,
2266             args: clean_generic_args(type_binding.gen_args, cx),
2267         },
2268         kind: match type_binding.kind {
2269             hir::TypeBindingKind::Equality { ref term } => {
2270                 TypeBindingKind::Equality { term: clean_hir_term(term, cx) }
2271             }
2272             hir::TypeBindingKind::Constraint { bounds } => TypeBindingKind::Constraint {
2273                 bounds: bounds.iter().filter_map(|b| clean_generic_bound(b, cx)).collect(),
2274             },
2275         },
2276     }
2277 }