src/librustdoc/visit_ast.rs

   1 //! The Rust AST Visitor. Extracts useful information and massages it into a form
   2 //! usable for `clean`.
   3
   4 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
   5 use rustc_hir as hir;
   6 use rustc_hir::def::{DefKind, Res};
   7 use rustc_hir::def_id::DefId;
   8 use rustc_hir::Node;
   9 use rustc_hir::CRATE_HIR_ID;
  10 use rustc_middle::middle::privacy::AccessLevel;
  11 use rustc_middle::ty::TyCtxt;
  12 use rustc_span::def_id::{CRATE_DEF_ID, LOCAL_CRATE};
  13 use rustc_span::symbol::{kw, sym, Symbol};
  14 use rustc_span::Span;
  15
  16 use std::mem;
  17
  18 use crate::clean::{self, cfg::Cfg, AttributesExt, NestedAttributesExt};
  19 use crate::core;
  20
  21 /// This module is used to store stuff from Rust's AST in a more convenient
  22 /// manner (and with prettier names) before cleaning.
  23 #[derive(Debug)]
  24 pub(crate) struct Module<'hir> {
  25     pub(crate) name: Symbol,
  26     pub(crate) where_inner: Span,
  27     pub(crate) mods: Vec<Module<'hir>>,
  28     pub(crate) id: hir::HirId,
  29     // (item, renamed)
  30     pub(crate) items: Vec<(&'hir hir::Item<'hir>, Option<Symbol>)>,
  31     pub(crate) foreigns: Vec<(&'hir hir::ForeignItem<'hir>, Option<Symbol>)>,
  32 }
  33
  34 impl Module<'_> {
  35     pub(crate) fn new(name: Symbol, id: hir::HirId, where_inner: Span) -> Self {
  36         Module { name, id, where_inner, mods: Vec::new(), items: Vec::new(), foreigns: Vec::new() }
  37     }
  38
  39     pub(crate) fn where_outer(&self, tcx: TyCtxt<'_>) -> Span {
  40         tcx.hir().span(self.id)
  41     }
  42 }
  43
  44 // FIXME: Should this be replaced with tcx.def_path_str?
  45 fn def_id_to_path(tcx: TyCtxt<'_>, did: DefId) -> Vec<Symbol> {
  46     let crate_name = tcx.crate_name(did.krate);
  47     let relative = tcx.def_path(did).data.into_iter().filter_map(|elem| elem.data.get_opt_name());
  48     std::iter::once(crate_name).chain(relative).collect()
  49 }
  50
  51 pub(crate) fn inherits_doc_hidden(tcx: TyCtxt<'_>, mut node: hir::HirId) -> bool {
  52     while let Some(id) = tcx.hir().get_enclosing_scope(node) {
  53         node = id;
  54         if tcx.hir().attrs(node).lists(sym::doc).has_word(sym::hidden) {
  55             return true;
  56         }
  57     }
  58     false
  59 }
  60
  61 // Also, is there some reason that this doesn't use the 'visit'
  62 // framework from syntax?.
  63
  64 pub(crate) struct RustdocVisitor<'a, 'tcx> {
  65     cx: &'a mut core::DocContext<'tcx>,
  66     view_item_stack: FxHashSet<hir::HirId>,
  67     inlining: bool,
  68     /// Are the current module and all of its parents public?
  69     inside_public_path: bool,
  70     exact_paths: FxHashMap<DefId, Vec<Symbol>>,
  71 }
  72
  73 impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
  74     pub(crate) fn new(cx: &'a mut core::DocContext<'tcx>) -> RustdocVisitor<'a, 'tcx> {
  75         // If the root is re-exported, terminate all recursion.
  76         let mut stack = FxHashSet::default();
  77         stack.insert(hir::CRATE_HIR_ID);
  78         RustdocVisitor {
  79             cx,
  80             view_item_stack: stack,
  81             inlining: false,
  82             inside_public_path: true,
  83             exact_paths: FxHashMap::default(),
  84         }
  85     }
  86
  87     fn store_path(&mut self, did: DefId) {
  88         let tcx = self.cx.tcx;
  89         self.exact_paths.entry(did).or_insert_with(|| def_id_to_path(tcx, did));
  90     }
  91
  92     pub(crate) fn visit(mut self) -> Module<'tcx> {
  93         let mut top_level_module = self.visit_mod_contents(
  94             hir::CRATE_HIR_ID,
  95             self.cx.tcx.hir().root_module(),
  96             self.cx.tcx.crate_name(LOCAL_CRATE),
  97         );
  98
  99         // `#[macro_export] macro_rules!` items are reexported at the top level of the
 100         // crate, regardless of where they're defined. We want to document the
 101         // top level rexport of the macro, not its original definition, since
 102         // the rexport defines the path that a user will actually see. Accordingly,
 103         // we add the rexport as an item here, and then skip over the original
 104         // definition in `visit_item()` below.
 105         //
 106         // We also skip `#[macro_export] macro_rules!` that have already been inserted,
 107         // it can happen if within the same module a `#[macro_export] macro_rules!`
 108         // is declared but also a reexport of itself producing two exports of the same
 109         // macro in the same module.
 110         let mut inserted = FxHashSet::default();
 111         for export in self.cx.tcx.module_reexports(CRATE_DEF_ID).unwrap_or(&[]) {
 112             if let Res::Def(DefKind::Macro(_), def_id) = export.res {
 113                 if let Some(local_def_id) = def_id.as_local() {
 114                     if self.cx.tcx.has_attr(def_id, sym::macro_export) {
 115                         if inserted.insert(def_id) {
 116                             let item = self.cx.tcx.hir().expect_item(local_def_id);
 117                             top_level_module.items.push((item, None));
 118                         }
 119                     }
 120                 }
 121             }
 122         }
 123
 124         self.cx.cache.hidden_cfg = self
 125             .cx
 126             .tcx
 127             .hir()
 128             .attrs(CRATE_HIR_ID)
 129             .iter()
 130             .filter(|attr| attr.has_name(sym::doc))
 131             .flat_map(|attr| attr.meta_item_list().into_iter().flatten())
 132             .filter(|attr| attr.has_name(sym::cfg_hide))
 133             .flat_map(|attr| {
 134                 attr.meta_item_list()
 135                     .unwrap_or(&[])
 136                     .iter()
 137                     .filter_map(|attr| {
 138                         Cfg::parse(attr.meta_item()?)
 139                             .map_err(|e| self.cx.sess().diagnostic().span_err(e.span, e.msg))
 140                             .ok()
 141                     })
 142                     .collect::<Vec<_>>()
 143             })
 144             .chain(
 145                 [Cfg::Cfg(sym::test, None), Cfg::Cfg(sym::doc, None), Cfg::Cfg(sym::doctest, None)]
 146                     .into_iter(),
 147             )
 148             .collect();
 149
 150         self.cx.cache.exact_paths = self.exact_paths;
 151         top_level_module
 152     }
 153
 154     fn visit_mod_contents(
 155         &mut self,
 156         id: hir::HirId,
 157         m: &'tcx hir::Mod<'tcx>,
 158         name: Symbol,
 159     ) -> Module<'tcx> {
 160         let mut om = Module::new(name, id, m.spans.inner_span);
 161         let def_id = self.cx.tcx.hir().local_def_id(id).to_def_id();
 162         // Keep track of if there were any private modules in the path.
 163         let orig_inside_public_path = self.inside_public_path;
 164         self.inside_public_path &= self.cx.tcx.visibility(def_id).is_public();
 165         for &i in m.item_ids {
 166             let item = self.cx.tcx.hir().item(i);
 167             if matches!(item.kind, hir::ItemKind::Use(_, hir::UseKind::Glob)) {
 168                 continue;
 169             }
 170             self.visit_item(item, None, &mut om);
 171         }
 172         for &i in m.item_ids {
 173             let item = self.cx.tcx.hir().item(i);
 174             // To match the way import precedence works, visit glob imports last.
 175             // Later passes in rustdoc will de-duplicate by name and kind, so if glob-
 176             // imported items appear last, then they'll be the ones that get discarded.
 177             if matches!(item.kind, hir::ItemKind::Use(_, hir::UseKind::Glob)) {
 178                 self.visit_item(item, None, &mut om);
 179             }
 180         }
 181         self.inside_public_path = orig_inside_public_path;
 182         om
 183     }
 184
 185     /// Tries to resolve the target of a `pub use` statement and inlines the
 186     /// target if it is defined locally and would not be documented otherwise,
 187     /// or when it is specifically requested with `please_inline`.
 188     /// (the latter is the case when the import is marked `doc(inline)`)
 189     ///
 190     /// Cross-crate inlining occurs later on during crate cleaning
 191     /// and follows different rules.
 192     ///
 193     /// Returns `true` if the target has been inlined.
 194     fn maybe_inline_local(
 195         &mut self,
 196         id: hir::HirId,
 197         res: Res,
 198         renamed: Option<Symbol>,
 199         glob: bool,
 200         om: &mut Module<'tcx>,
 201         please_inline: bool,
 202     ) -> bool {
 203         debug!("maybe_inline_local res: {:?}", res);
 204
 205         if self.cx.output_format.is_json() {
 206             return false;
 207         }
 208
 209         let tcx = self.cx.tcx;
 210         let Some(res_did) = res.opt_def_id() else {
 211             return false;
 212         };
 213
 214         let use_attrs = tcx.hir().attrs(id);
 215         // Don't inline `doc(hidden)` imports so they can be stripped at a later stage.
 216         let is_no_inline = use_attrs.lists(sym::doc).has_word(sym::no_inline)
 217             || use_attrs.lists(sym::doc).has_word(sym::hidden);
 218
 219         // For cross-crate impl inlining we need to know whether items are
 220         // reachable in documentation -- a previously unreachable item can be
 221         // made reachable by cross-crate inlining which we're checking here.
 222         // (this is done here because we need to know this upfront).
 223         if !res_did.is_local() && !is_no_inline {
 224             let attrs = clean::inline::load_attrs(self.cx, res_did);
 225             let self_is_hidden = attrs.lists(sym::doc).has_word(sym::hidden);
 226             if !self_is_hidden {
 227                 if let Res::Def(kind, did) = res {
 228                     if kind == DefKind::Mod {
 229                         crate::visit_lib::LibEmbargoVisitor::new(self.cx).visit_mod(did)
 230                     } else {
 231                         // All items need to be handled here in case someone wishes to link
 232                         // to them with intra-doc links
 233                         self.cx.cache.access_levels.map.insert(did, AccessLevel::Public);
 234                     }
 235                 }
 236             }
 237             return false;
 238         }
 239
 240         let res_hir_id = match res_did.as_local() {
 241             Some(n) => tcx.hir().local_def_id_to_hir_id(n),
 242             None => return false,
 243         };
 244
 245         let is_private = !self.cx.cache.access_levels.is_public(res_did);
 246         let is_hidden = inherits_doc_hidden(self.cx.tcx, res_hir_id);
 247
 248         // Only inline if requested or if the item would otherwise be stripped.
 249         if (!please_inline && !is_private && !is_hidden) || is_no_inline {
 250             return false;
 251         }
 252
 253         if !self.view_item_stack.insert(res_hir_id) {
 254             return false;
 255         }
 256
 257         let ret = match tcx.hir().get(res_hir_id) {
 258             Node::Item(&hir::Item { kind: hir::ItemKind::Mod(ref m), .. }) if glob => {
 259                 let prev = mem::replace(&mut self.inlining, true);
 260                 for &i in m.item_ids {
 261                     let i = self.cx.tcx.hir().item(i);
 262                     self.visit_item(i, None, om);
 263                 }
 264                 self.inlining = prev;
 265                 true
 266             }
 267             Node::Item(it) if !glob => {
 268                 let prev = mem::replace(&mut self.inlining, true);
 269                 self.visit_item(it, renamed, om);
 270                 self.inlining = prev;
 271                 true
 272             }
 273             Node::ForeignItem(it) if !glob => {
 274                 let prev = mem::replace(&mut self.inlining, true);
 275                 self.visit_foreign_item(it, renamed, om);
 276                 self.inlining = prev;
 277                 true
 278             }
 279             _ => false,
 280         };
 281         self.view_item_stack.remove(&res_hir_id);
 282         ret
 283     }
 284
 285     fn visit_item(
 286         &mut self,
 287         item: &'tcx hir::Item<'_>,
 288         renamed: Option<Symbol>,
 289         om: &mut Module<'tcx>,
 290     ) {
 291         debug!("visiting item {:?}", item);
 292         let name = renamed.unwrap_or(item.ident.name);
 293
 294         let def_id = item.def_id.to_def_id();
 295         let is_pub = self.cx.tcx.visibility(def_id).is_public();
 296
 297         if is_pub {
 298             self.store_path(item.def_id.to_def_id());
 299         }
 300
 301         match item.kind {
 302             hir::ItemKind::ForeignMod { items, .. } => {
 303                 for item in items {
 304                     let item = self.cx.tcx.hir().foreign_item(item.id);
 305                     self.visit_foreign_item(item, None, om);
 306                 }
 307             }
 308             // If we're inlining, skip private items or item reexported as "_".
 309             _ if self.inlining && (!is_pub || renamed == Some(kw::Underscore)) => {}
 310             hir::ItemKind::GlobalAsm(..) => {}
 311             hir::ItemKind::Use(_, hir::UseKind::ListStem) => {}
 312             hir::ItemKind::Use(path, kind) => {
 313                 let is_glob = kind == hir::UseKind::Glob;
 314
 315                 // Struct and variant constructors and proc macro stubs always show up alongside
 316                 // their definitions, we've already processed them so just discard these.
 317                 if let Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) = path.res {
 318                     return;
 319                 }
 320
 321                 let attrs = self.cx.tcx.hir().attrs(item.hir_id());
 322
 323                 // If there was a private module in the current path then don't bother inlining
 324                 // anything as it will probably be stripped anyway.
 325                 if is_pub && self.inside_public_path {
 326                     let please_inline = attrs.iter().any(|item| match item.meta_item_list() {
 327                         Some(ref list) if item.has_name(sym::doc) => {
 328                             list.iter().any(|i| i.has_name(sym::inline))
 329                         }
 330                         _ => false,
 331                     });
 332                     let ident = if is_glob { None } else { Some(name) };
 333                     if self.maybe_inline_local(
 334                         item.hir_id(),
 335                         path.res,
 336                         ident,
 337                         is_glob,
 338                         om,
 339                         please_inline,
 340                     ) {
 341                         return;
 342                     }
 343                 }
 344
 345                 om.items.push((item, renamed))
 346             }
 347             hir::ItemKind::Macro(ref macro_def, _) => {
 348                 // `#[macro_export] macro_rules!` items are handled separately in `visit()`,
 349                 // above, since they need to be documented at the module top level. Accordingly,
 350                 // we only want to handle macros if one of three conditions holds:
 351                 //
 352                 // 1. This macro was defined by `macro`, and thus isn't covered by the case
 353                 //    above.
 354                 // 2. This macro isn't marked with `#[macro_export]`, and thus isn't covered
 355                 //    by the case above.
 356                 // 3. We're inlining, since a reexport where inlining has been requested
 357                 //    should be inlined even if it is also documented at the top level.
 358
 359                 let def_id = item.def_id.to_def_id();
 360                 let is_macro_2_0 = !macro_def.macro_rules;
 361                 let nonexported = !self.cx.tcx.has_attr(def_id, sym::macro_export);
 362
 363                 if is_macro_2_0 || nonexported || self.inlining {
 364                     om.items.push((item, renamed));
 365                 }
 366             }
 367             hir::ItemKind::Mod(ref m) => {
 368                 om.mods.push(self.visit_mod_contents(item.hir_id(), m, name));
 369             }
 370             hir::ItemKind::Fn(..)
 371             | hir::ItemKind::ExternCrate(..)
 372             | hir::ItemKind::Enum(..)
 373             | hir::ItemKind::Struct(..)
 374             | hir::ItemKind::Union(..)
 375             | hir::ItemKind::TyAlias(..)
 376             | hir::ItemKind::OpaqueTy(..)
 377             | hir::ItemKind::Static(..)
 378             | hir::ItemKind::Trait(..)
 379             | hir::ItemKind::TraitAlias(..) => om.items.push((item, renamed)),
 380             hir::ItemKind::Const(..) => {
 381                 // Underscore constants do not correspond to a nameable item and
 382                 // so are never useful in documentation.
 383                 if name != kw::Underscore {
 384                     om.items.push((item, renamed));
 385                 }
 386             }
 387             hir::ItemKind::Impl(impl_) => {
 388                 // Don't duplicate impls when inlining or if it's implementing a trait, we'll pick
 389                 // them up regardless of where they're located.
 390                 if !self.inlining && impl_.of_trait.is_none() {
 391                     om.items.push((item, None));
 392                 }
 393             }
 394         }
 395     }
 396
 397     fn visit_foreign_item(
 398         &mut self,
 399         item: &'tcx hir::ForeignItem<'_>,
 400         renamed: Option<Symbol>,
 401         om: &mut Module<'tcx>,
 402     ) {
 403         // If inlining we only want to include public functions.
 404         if !self.inlining || self.cx.tcx.visibility(item.def_id).is_public() {
 405             om.foreigns.push((item, renamed));
 406         }
 407     }
 408 }