src/librustdoc/clean/inline.rs

   1 //! Support for inlining external documentation into the current AST.
   2
   3 use std::iter::once;
   4
   5 use syntax::ast;
   6 use syntax::symbol::sym;
   7 use syntax_pos::hygiene::MacroKind;
   8 use syntax_pos::Span;
   9
  10 use rustc::hir;
  11 use rustc::hir::def::{Res, DefKind, CtorKind};
  12 use rustc::hir::def_id::DefId;
  13 use rustc_metadata::creader::LoadedMacro;
  14 use rustc::ty;
  15 use rustc::util::nodemap::FxHashSet;
  16
  17 use crate::core::DocContext;
  18 use crate::doctree;
  19 use crate::clean::{
  20     self,
  21     GetDefId,
  22     ToSource,
  23     TypeKind
  24 };
  25
  26 use super::Clean;
  27
  28 type Attrs<'hir> = rustc::ty::Attributes<'hir>;
  29
  30 /// Attempt to inline a definition into this AST.
  31 ///
  32 /// This function will fetch the definition specified, and if it is
  33 /// from another crate it will attempt to inline the documentation
  34 /// from the other crate into this crate.
  35 ///
  36 /// This is primarily used for `pub use` statements which are, in general,
  37 /// implementation details. Inlining the documentation should help provide a
  38 /// better experience when reading the documentation in this use case.
  39 ///
  40 /// The returned value is `None` if the definition could not be inlined,
  41 /// and `Some` of a vector of items if it was successfully expanded.
  42 pub fn try_inline(
  43     cx: &DocContext<'_>,
  44     res: Res,
  45     name: ast::Name,
  46     attrs: Option<Attrs<'_>>,
  47     visited: &mut FxHashSet<DefId>
  48 ) -> Option<Vec<clean::Item>> {
  49     let did = if let Some(did) = res.opt_def_id() {
  50         did
  51     } else {
  52         return None;
  53     };
  54     if did.is_local() { return None }
  55     let mut ret = Vec::new();
  56
  57     let attrs_clone = attrs.clone();
  58
  59     let inner = match res {
  60         Res::Def(DefKind::Trait, did) => {
  61             record_extern_fqn(cx, did, clean::TypeKind::Trait);
  62             ret.extend(build_impls(cx, did, attrs));
  63             clean::TraitItem(build_external_trait(cx, did))
  64         }
  65         Res::Def(DefKind::Fn, did) => {
  66             record_extern_fqn(cx, did, clean::TypeKind::Function);
  67             clean::FunctionItem(build_external_function(cx, did))
  68         }
  69         Res::Def(DefKind::Struct, did) => {
  70             record_extern_fqn(cx, did, clean::TypeKind::Struct);
  71             ret.extend(build_impls(cx, did, attrs));
  72             clean::StructItem(build_struct(cx, did))
  73         }
  74         Res::Def(DefKind::Union, did) => {
  75             record_extern_fqn(cx, did, clean::TypeKind::Union);
  76             ret.extend(build_impls(cx, did, attrs));
  77             clean::UnionItem(build_union(cx, did))
  78         }
  79         Res::Def(DefKind::TyAlias, did) => {
  80             record_extern_fqn(cx, did, clean::TypeKind::Typedef);
  81             ret.extend(build_impls(cx, did, attrs));
  82             clean::TypedefItem(build_type_alias(cx, did), false)
  83         }
  84         Res::Def(DefKind::Enum, did) => {
  85             record_extern_fqn(cx, did, clean::TypeKind::Enum);
  86             ret.extend(build_impls(cx, did, attrs));
  87             clean::EnumItem(build_enum(cx, did))
  88         }
  89         Res::Def(DefKind::ForeignTy, did) => {
  90             record_extern_fqn(cx, did, clean::TypeKind::Foreign);
  91             ret.extend(build_impls(cx, did, attrs));
  92             clean::ForeignTypeItem
  93         }
  94         // Never inline enum variants but leave them shown as re-exports.
  95         Res::Def(DefKind::Variant, _) => return None,
  96         // Assume that enum variants and struct types are re-exported next to
  97         // their constructors.
  98         Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) => return Some(Vec::new()),
  99         Res::Def(DefKind::Mod, did) => {
 100             record_extern_fqn(cx, did, clean::TypeKind::Module);
 101             clean::ModuleItem(build_module(cx, did, visited))
 102         }
 103         Res::Def(DefKind::Static, did) => {
 104             record_extern_fqn(cx, did, clean::TypeKind::Static);
 105             clean::StaticItem(build_static(cx, did, cx.tcx.is_mutable_static(did)))
 106         }
 107         Res::Def(DefKind::Const, did) => {
 108             record_extern_fqn(cx, did, clean::TypeKind::Const);
 109             clean::ConstantItem(build_const(cx, did))
 110         }
 111         Res::Def(DefKind::Macro(kind), did) => {
 112             let mac = build_macro(cx, did, name);
 113
 114             let type_kind = match kind {
 115                 MacroKind::Bang => TypeKind::Macro,
 116                 MacroKind::Attr => TypeKind::Attr,
 117                 MacroKind::Derive => TypeKind::Derive
 118             };
 119             record_extern_fqn(cx, did, type_kind);
 120             mac
 121         }
 122         _ => return None,
 123     };
 124
 125     let target_attrs = load_attrs(cx, did);
 126     let attrs = merge_attrs(cx, target_attrs,  attrs_clone);
 127
 128     cx.renderinfo.borrow_mut().inlined.insert(did);
 129     ret.push(clean::Item {
 130         source: cx.tcx.def_span(did).clean(cx),
 131         name: Some(name.clean(cx)),
 132         attrs,
 133         inner,
 134         visibility: clean::Public,
 135         stability: cx.tcx.lookup_stability(did).clean(cx),
 136         deprecation: cx.tcx.lookup_deprecation(did).clean(cx),
 137         def_id: did,
 138     });
 139     Some(ret)
 140 }
 141
 142 pub fn try_inline_glob(cx: &DocContext<'_>, res: Res, visited: &mut FxHashSet<DefId>)
 143     -> Option<Vec<clean::Item>>
 144 {
 145     if res == Res::Err { return None }
 146     let did = res.def_id();
 147     if did.is_local() { return None }
 148
 149     match res {
 150         Res::Def(DefKind::Mod, did) => {
 151             let m = build_module(cx, did, visited);
 152             Some(m.items)
 153         }
 154         // glob imports on things like enums aren't inlined even for local exports, so just bail
 155         _ => None,
 156     }
 157 }
 158
 159 pub fn load_attrs<'hir>(cx: &DocContext<'hir>, did: DefId) -> Attrs<'hir> {
 160     cx.tcx.get_attrs(did)
 161 }
 162
 163 /// Record an external fully qualified name in the external_paths cache.
 164 ///
 165 /// These names are used later on by HTML rendering to generate things like
 166 /// source links back to the original item.
 167 pub fn record_extern_fqn(cx: &DocContext<'_>, did: DefId, kind: clean::TypeKind) {
 168     let crate_name = cx.tcx.crate_name(did.krate).to_string();
 169
 170     let relative = cx.tcx.def_path(did).data.into_iter().filter_map(|elem| {
 171         // extern blocks have an empty name
 172         let s = elem.data.to_string();
 173         if !s.is_empty() {
 174             Some(s)
 175         } else {
 176             None
 177         }
 178     });
 179     let fqn = if let clean::TypeKind::Macro = kind {
 180         vec![crate_name, relative.last().expect("relative was empty")]
 181     } else {
 182         once(crate_name).chain(relative).collect()
 183     };
 184
 185     if did.is_local() {
 186         cx.renderinfo.borrow_mut().exact_paths.insert(did, fqn);
 187     } else {
 188         cx.renderinfo.borrow_mut().external_paths.insert(did, (fqn, kind));
 189     }
 190 }
 191
 192 pub fn build_external_trait(cx: &DocContext<'_>, did: DefId) -> clean::Trait {
 193     let auto_trait = cx.tcx.trait_def(did).has_auto_impl;
 194     let trait_items = cx.tcx.associated_items(did).map(|item| item.clean(cx)).collect();
 195     let predicates = cx.tcx.predicates_of(did);
 196     let generics = (cx.tcx.generics_of(did), predicates).clean(cx);
 197     let generics = filter_non_trait_generics(did, generics);
 198     let (generics, supertrait_bounds) = separate_supertrait_bounds(generics);
 199     let is_spotlight = load_attrs(cx, did).clean(cx).has_doc_flag(sym::spotlight);
 200     let is_auto = cx.tcx.trait_is_auto(did);
 201     clean::Trait {
 202         auto: auto_trait,
 203         unsafety: cx.tcx.trait_def(did).unsafety,
 204         generics,
 205         items: trait_items,
 206         bounds: supertrait_bounds,
 207         is_spotlight,
 208         is_auto,
 209     }
 210 }
 211
 212 fn build_external_function(cx: &DocContext<'_>, did: DefId) -> clean::Function {
 213     let sig = cx.tcx.fn_sig(did);
 214
 215     let constness = if cx.tcx.is_min_const_fn(did) {
 216         hir::Constness::Const
 217     } else {
 218         hir::Constness::NotConst
 219     };
 220     let asyncness =  cx.tcx.asyncness(did);
 221     let predicates = cx.tcx.predicates_of(did);
 222     let (generics, decl) = clean::enter_impl_trait(cx, || {
 223         ((cx.tcx.generics_of(did), predicates).clean(cx), (did, sig).clean(cx))
 224     });
 225     let (all_types, ret_types) = clean::get_all_types(&generics, &decl, cx);
 226     clean::Function {
 227         decl,
 228         generics,
 229         header: hir::FnHeader {
 230             unsafety: sig.unsafety(),
 231             abi: sig.abi(),
 232             constness,
 233             asyncness,
 234         },
 235         all_types,
 236         ret_types,
 237     }
 238 }
 239
 240 fn build_enum(cx: &DocContext<'_>, did: DefId) -> clean::Enum {
 241     let predicates = cx.tcx.explicit_predicates_of(did);
 242
 243     clean::Enum {
 244         generics: (cx.tcx.generics_of(did), predicates).clean(cx),
 245         variants_stripped: false,
 246         variants: cx.tcx.adt_def(did).variants.clean(cx),
 247     }
 248 }
 249
 250 fn build_struct(cx: &DocContext<'_>, did: DefId) -> clean::Struct {
 251     let predicates = cx.tcx.explicit_predicates_of(did);
 252     let variant = cx.tcx.adt_def(did).non_enum_variant();
 253
 254     clean::Struct {
 255         struct_type: match variant.ctor_kind {
 256             CtorKind::Fictive => doctree::Plain,
 257             CtorKind::Fn => doctree::Tuple,
 258             CtorKind::Const => doctree::Unit,
 259         },
 260         generics: (cx.tcx.generics_of(did), predicates).clean(cx),
 261         fields: variant.fields.clean(cx),
 262         fields_stripped: false,
 263     }
 264 }
 265
 266 fn build_union(cx: &DocContext<'_>, did: DefId) -> clean::Union {
 267     let predicates = cx.tcx.explicit_predicates_of(did);
 268     let variant = cx.tcx.adt_def(did).non_enum_variant();
 269
 270     clean::Union {
 271         struct_type: doctree::Plain,
 272         generics: (cx.tcx.generics_of(did), predicates).clean(cx),
 273         fields: variant.fields.clean(cx),
 274         fields_stripped: false,
 275     }
 276 }
 277
 278 fn build_type_alias(cx: &DocContext<'_>, did: DefId) -> clean::Typedef {
 279     let predicates = cx.tcx.explicit_predicates_of(did);
 280
 281     clean::Typedef {
 282         type_: cx.tcx.type_of(did).clean(cx),
 283         generics: (cx.tcx.generics_of(did), predicates).clean(cx),
 284     }
 285 }
 286
 287 pub fn build_impls(cx: &DocContext<'_>, did: DefId, attrs: Option<Attrs<'_>>) -> Vec<clean::Item> {
 288     let tcx = cx.tcx;
 289     let mut impls = Vec::new();
 290
 291     for &did in tcx.inherent_impls(did).iter() {
 292         build_impl(cx, did, attrs.clone(), &mut impls);
 293     }
 294
 295     impls
 296 }
 297
 298 fn merge_attrs(cx: &DocContext<'_>, attrs: Attrs<'_>, other_attrs: Option<Attrs<'_>>
 299 ) -> clean::Attributes {
 300     let mut merged_attrs: Vec<ast::Attribute> = Vec::with_capacity(attrs.len());
 301     // If we have additional attributes (from a re-export),
 302     // always insert them first. This ensure that re-export
 303     // doc comments show up before the original doc comments
 304     // when we render them.
 305     if let Some(a) = other_attrs {
 306         merged_attrs.extend(a.iter().cloned());
 307     }
 308     merged_attrs.extend(attrs.to_vec());
 309     merged_attrs.clean(cx)
 310 }
 311
 312 pub fn build_impl(cx: &DocContext<'_>, did: DefId, attrs: Option<Attrs<'_>>,
 313                   ret: &mut Vec<clean::Item>
 314 ) {
 315     if !cx.renderinfo.borrow_mut().inlined.insert(did) {
 316         return
 317     }
 318
 319     let attrs = merge_attrs(cx, load_attrs(cx, did), attrs);
 320
 321
 322     let tcx = cx.tcx;
 323     let associated_trait = tcx.impl_trait_ref(did);
 324
 325     // Only inline impl if the implemented trait is
 326     // reachable in rustdoc generated documentation
 327     if !did.is_local() {
 328         if let Some(traitref) = associated_trait {
 329             if !cx.renderinfo.borrow().access_levels.is_public(traitref.def_id) {
 330                 return
 331             }
 332         }
 333     }
 334
 335     let for_ = if let Some(hir_id) = tcx.hir().as_local_hir_id(did) {
 336         match tcx.hir().expect_item(hir_id).kind {
 337             hir::ItemKind::Impl(.., ref t, _) => {
 338                 t.clean(cx)
 339             }
 340             _ => panic!("did given to build_impl was not an impl"),
 341         }
 342     } else {
 343         tcx.type_of(did).clean(cx)
 344     };
 345
 346     // Only inline impl if the implementing type is
 347     // reachable in rustdoc generated documentation
 348     if !did.is_local() {
 349         if let Some(did) = for_.def_id() {
 350             if !cx.renderinfo.borrow().access_levels.is_public(did) {
 351                 return
 352             }
 353         }
 354     }
 355
 356     let predicates = tcx.explicit_predicates_of(did);
 357     let (trait_items, generics) = if let Some(hir_id) = tcx.hir().as_local_hir_id(did) {
 358         match tcx.hir().expect_item(hir_id).kind {
 359             hir::ItemKind::Impl(.., ref gen, _, _, ref item_ids) => {
 360                 (
 361                     item_ids.iter()
 362                             .map(|ii| tcx.hir().impl_item(ii.id).clean(cx))
 363                             .collect::<Vec<_>>(),
 364                     gen.clean(cx),
 365                 )
 366             }
 367             _ => panic!("did given to build_impl was not an impl"),
 368         }
 369     } else {
 370         (
 371             tcx.associated_items(did).filter_map(|item| {
 372                 if associated_trait.is_some() || item.vis == ty::Visibility::Public {
 373                     Some(item.clean(cx))
 374                 } else {
 375                     None
 376                 }
 377             }).collect::<Vec<_>>(),
 378             clean::enter_impl_trait(cx, || {
 379                 (tcx.generics_of(did), predicates).clean(cx)
 380             }),
 381         )
 382     };
 383     let polarity = tcx.impl_polarity(did);
 384     let trait_ = associated_trait.clean(cx).map(|bound| {
 385         match bound {
 386             clean::GenericBound::TraitBound(polyt, _) => polyt.trait_,
 387             clean::GenericBound::Outlives(..) => unreachable!(),
 388         }
 389     });
 390     if trait_.def_id() == tcx.lang_items().deref_trait() {
 391         super::build_deref_target_impls(cx, &trait_items, ret);
 392     }
 393     if let Some(trait_did) = trait_.def_id() {
 394         record_extern_trait(cx, trait_did);
 395     }
 396
 397     let provided = trait_.def_id().map(|did| {
 398         tcx.provided_trait_methods(did)
 399            .into_iter()
 400            .map(|meth| meth.ident.to_string())
 401            .collect()
 402     }).unwrap_or_default();
 403
 404     debug!("build_impl: impl {:?} for {:?}", trait_.def_id(), for_.def_id());
 405
 406     ret.push(clean::Item {
 407         inner: clean::ImplItem(clean::Impl {
 408             unsafety: hir::Unsafety::Normal,
 409             generics,
 410             provided_trait_methods: provided,
 411             trait_,
 412             for_,
 413             items: trait_items,
 414             polarity: Some(polarity.clean(cx)),
 415             synthetic: false,
 416             blanket_impl: None,
 417         }),
 418         source: tcx.def_span(did).clean(cx),
 419         name: None,
 420         attrs,
 421         visibility: clean::Inherited,
 422         stability: tcx.lookup_stability(did).clean(cx),
 423         deprecation: tcx.lookup_deprecation(did).clean(cx),
 424         def_id: did,
 425     });
 426 }
 427
 428 fn build_module(
 429     cx: &DocContext<'_>,
 430     did: DefId,
 431     visited: &mut FxHashSet<DefId>
 432 ) -> clean::Module {
 433     let mut items = Vec::new();
 434     fill_in(cx, did, &mut items, visited);
 435     return clean::Module {
 436         items,
 437         is_crate: false,
 438     };
 439
 440     fn fill_in(cx: &DocContext<'_>, did: DefId, items: &mut Vec<clean::Item>,
 441                visited: &mut FxHashSet<DefId>) {
 442         // If we're re-exporting a re-export it may actually re-export something in
 443         // two namespaces, so the target may be listed twice. Make sure we only
 444         // visit each node at most once.
 445         for &item in cx.tcx.item_children(did).iter() {
 446             let def_id = item.res.def_id();
 447             if item.vis == ty::Visibility::Public {
 448                 if did == def_id || !visited.insert(def_id) { continue }
 449                 if let Some(i) = try_inline(cx, item.res, item.ident.name, None, visited) {
 450                     items.extend(i)
 451                 }
 452             }
 453         }
 454     }
 455 }
 456
 457 pub fn print_inlined_const(cx: &DocContext<'_>, did: DefId) -> String {
 458     if let Some(node_id) = cx.tcx.hir().as_local_hir_id(did) {
 459         cx.tcx.hir().hir_to_pretty_string(node_id)
 460     } else {
 461         cx.tcx.rendered_const(did)
 462     }
 463 }
 464
 465 fn build_const(cx: &DocContext<'_>, did: DefId) -> clean::Constant {
 466     clean::Constant {
 467         type_: cx.tcx.type_of(did).clean(cx),
 468         expr: print_inlined_const(cx, did)
 469     }
 470 }
 471
 472 fn build_static(cx: &DocContext<'_>, did: DefId, mutable: bool) -> clean::Static {
 473     clean::Static {
 474         type_: cx.tcx.type_of(did).clean(cx),
 475         mutability: if mutable {clean::Mutable} else {clean::Immutable},
 476         expr: "\n\n\n".to_string(), // trigger the "[definition]" links
 477     }
 478 }
 479
 480 fn build_macro(cx: &DocContext<'_>, did: DefId, name: ast::Name) -> clean::ItemEnum {
 481     let imported_from = cx.tcx.original_crate_name(did.krate);
 482     match cx.enter_resolver(|r| r.cstore().load_macro_untracked(did, cx.sess())) {
 483         LoadedMacro::MacroDef(def, _) => {
 484             let matchers: hir::HirVec<Span> = if let ast::ItemKind::MacroDef(ref def) = def.kind {
 485                 let tts: Vec<_> = def.body.inner_tokens().into_trees().collect();
 486                 tts.chunks(4).map(|arm| arm[0].span()).collect()
 487             } else {
 488                 unreachable!()
 489             };
 490
 491             let source = format!("macro_rules! {} {{\n{}}}",
 492                                  name.clean(cx),
 493                                  matchers.iter().map(|span| {
 494                                      format!("    {} => {{ ... }};\n", span.to_src(cx))
 495                                  }).collect::<String>());
 496
 497             clean::MacroItem(clean::Macro {
 498                 source,
 499                 imported_from: Some(imported_from).clean(cx),
 500             })
 501         }
 502         LoadedMacro::ProcMacro(ext) => {
 503             clean::ProcMacroItem(clean::ProcMacro {
 504                 kind: ext.macro_kind(),
 505                 helpers: ext.helper_attrs.clean(cx),
 506             })
 507         }
 508     }
 509 }
 510
 511 /// A trait's generics clause actually contains all of the predicates for all of
 512 /// its associated types as well. We specifically move these clauses to the
 513 /// associated types instead when displaying, so when we're generating the
 514 /// generics for the trait itself we need to be sure to remove them.
 515 /// We also need to remove the implied "recursive" Self: Trait bound.
 516 ///
 517 /// The inverse of this filtering logic can be found in the `Clean`
 518 /// implementation for `AssociatedType`
 519 fn filter_non_trait_generics(trait_did: DefId, mut g: clean::Generics) -> clean::Generics {
 520     for pred in &mut g.where_predicates {
 521         match *pred {
 522             clean::WherePredicate::BoundPredicate {
 523                 ty: clean::Generic(ref s),
 524                 ref mut bounds
 525             } if *s == "Self" => {
 526                 bounds.retain(|bound| {
 527                     match *bound {
 528                         clean::GenericBound::TraitBound(clean::PolyTrait {
 529                             trait_: clean::ResolvedPath { did, .. },
 530                             ..
 531                         }, _) => did != trait_did,
 532                         _ => true
 533                     }
 534                 });
 535             }
 536             _ => {}
 537         }
 538     }
 539
 540     g.where_predicates.retain(|pred| {
 541         match *pred {
 542             clean::WherePredicate::BoundPredicate {
 543                 ty: clean::QPath {
 544                     self_type: box clean::Generic(ref s),
 545                     trait_: box clean::ResolvedPath { did, .. },
 546                     name: ref _name,
 547                 }, ref bounds
 548             } => !(*s == "Self" && did == trait_did) && !bounds.is_empty(),
 549             _ => true,
 550         }
 551     });
 552     g
 553 }
 554
 555 /// Supertrait bounds for a trait are also listed in the generics coming from
 556 /// the metadata for a crate, so we want to separate those out and create a new
 557 /// list of explicit supertrait bounds to render nicely.
 558 fn separate_supertrait_bounds(mut g: clean::Generics)
 559                               -> (clean::Generics, Vec<clean::GenericBound>) {
 560     let mut ty_bounds = Vec::new();
 561     g.where_predicates.retain(|pred| {
 562         match *pred {
 563             clean::WherePredicate::BoundPredicate {
 564                 ty: clean::Generic(ref s),
 565                 ref bounds
 566             } if *s == "Self" => {
 567                 ty_bounds.extend(bounds.iter().cloned());
 568                 false
 569             }
 570             _ => true,
 571         }
 572     });
 573     (g, ty_bounds)
 574 }
 575
 576 pub fn record_extern_trait(cx: &DocContext<'_>, did: DefId) {
 577     if did.is_local() {
 578         return;
 579     }
 580
 581     {
 582         if cx.external_traits.borrow().contains_key(&did) ||
 583             cx.active_extern_traits.borrow().contains(&did)
 584         {
 585             return;
 586         }
 587     }
 588
 589     cx.active_extern_traits.borrow_mut().insert(did);
 590
 591     debug!("record_extern_trait: {:?}", did);
 592     let trait_ = build_external_trait(cx, did);
 593
 594     cx.external_traits.borrow_mut().insert(did, trait_);
 595     cx.active_extern_traits.borrow_mut().remove(&did);
 596 }