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_middle::middle::privacy::AccessLevel;
  10 use rustc_middle::ty::TyCtxt;
  11 use rustc_span::source_map::Spanned;
  12 use rustc_span::symbol::{kw, sym, Symbol};
  13 use rustc_span::{self, Span};
  14
  15 use std::mem;
  16
  17 use crate::clean::{self, AttributesExt, NestedAttributesExt};
  18 use crate::core;
  19 use crate::doctree::*;
  20
  21 // FIXME: Should this be replaced with tcx.def_path_str?
  22 fn def_id_to_path(tcx: TyCtxt<'_>, did: DefId) -> Vec<String> {
  23     let crate_name = tcx.crate_name(did.krate).to_string();
  24     let relative = tcx.def_path(did).data.into_iter().filter_map(|elem| {
  25         // extern blocks have an empty name
  26         let s = elem.data.to_string();
  27         if !s.is_empty() { Some(s) } else { None }
  28     });
  29     std::iter::once(crate_name).chain(relative).collect()
  30 }
  31
  32 crate fn inherits_doc_hidden(tcx: TyCtxt<'_>, mut node: hir::HirId) -> bool {
  33     while let Some(id) = tcx.hir().get_enclosing_scope(node) {
  34         node = id;
  35         if tcx.hir().attrs(node).lists(sym::doc).has_word(sym::hidden) {
  36             return true;
  37         }
  38     }
  39     false
  40 }
  41
  42 // Also, is there some reason that this doesn't use the 'visit'
  43 // framework from syntax?.
  44
  45 crate struct RustdocVisitor<'a, 'tcx> {
  46     cx: &'a mut core::DocContext<'tcx>,
  47     view_item_stack: FxHashSet<hir::HirId>,
  48     inlining: bool,
  49     /// Are the current module and all of its parents public?
  50     inside_public_path: bool,
  51     exact_paths: FxHashMap<DefId, Vec<String>>,
  52 }
  53
  54 impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
  55     crate fn new(cx: &'a mut core::DocContext<'tcx>) -> RustdocVisitor<'a, 'tcx> {
  56         // If the root is re-exported, terminate all recursion.
  57         let mut stack = FxHashSet::default();
  58         stack.insert(hir::CRATE_HIR_ID);
  59         RustdocVisitor {
  60             cx,
  61             view_item_stack: stack,
  62             inlining: false,
  63             inside_public_path: true,
  64             exact_paths: FxHashMap::default(),
  65         }
  66     }
  67
  68     fn store_path(&mut self, did: DefId) {
  69         let tcx = self.cx.tcx;
  70         self.exact_paths.entry(did).or_insert_with(|| def_id_to_path(tcx, did));
  71     }
  72
  73     crate fn visit(mut self, krate: &'tcx hir::Crate<'_>) -> Module<'tcx> {
  74         let span = krate.item.inner;
  75         let mut top_level_module = self.visit_mod_contents(
  76             span,
  77             &Spanned { span, node: hir::VisibilityKind::Public },
  78             hir::CRATE_HIR_ID,
  79             &krate.item,
  80             self.cx.tcx.crate_name,
  81         );
  82         // Attach the crate's exported macros to the top-level module.
  83         // In the case of macros 2.0 (`pub macro`), and for built-in `derive`s or attributes as
  84         // well (_e.g._, `Copy`), these are wrongly bundled in there too, so we need to fix that by
  85         // moving them back to their correct locations.
  86         'exported_macros: for def in krate.exported_macros {
  87             // The `def` of a macro in `exported_macros` should correspond to either:
  88             //  - a `#[macro_export] macro_rules!` macro,
  89             //  - a built-in `derive` (or attribute) macro such as the ones in `::core`,
  90             //  - a `pub macro`.
  91             // Only the last two need to be fixed, thus:
  92             if def.ast.macro_rules {
  93                 top_level_module.macros.push((def, None));
  94                 continue 'exported_macros;
  95             }
  96             let tcx = self.cx.tcx;
  97             // Note: this is not the same as `.parent_module()`. Indeed, the latter looks
  98             // for the closest module _ancestor_, which is not necessarily a direct parent
  99             // (since a direct parent isn't necessarily a module, c.f. #77828).
 100             let macro_parent_def_id = {
 101                 use rustc_middle::ty::DefIdTree;
 102                 tcx.parent(def.def_id.to_def_id()).unwrap()
 103             };
 104             let macro_parent_path = tcx.def_path(macro_parent_def_id);
 105             // HACK: rustdoc has no way to lookup `doctree::Module`s by their HirId. Instead,
 106             // lookup the module by its name, by looking at each path segment one at a time.
 107             let mut cur_mod = &mut top_level_module;
 108             for path_segment in macro_parent_path.data {
 109                 // Path segments may refer to a module (in which case they belong to the type
 110                 // namespace), which is _necessary_ for the macro to be accessible outside it
 111                 // (no "associated macros" as of yet). Else we bail with an outer `continue`.
 112                 let path_segment_ty_ns = match path_segment.data {
 113                     rustc_hir::definitions::DefPathData::TypeNs(symbol) => symbol,
 114                     _ => continue 'exported_macros,
 115                 };
 116                 // Descend into the child module that matches this path segment (if any).
 117                 match cur_mod.mods.iter_mut().find(|child| child.name == path_segment_ty_ns) {
 118                     Some(child_mod) => cur_mod = &mut *child_mod,
 119                     None => continue 'exported_macros,
 120                 }
 121             }
 122             let cur_mod_def_id = tcx.hir().local_def_id(cur_mod.id).to_def_id();
 123             assert_eq!(cur_mod_def_id, macro_parent_def_id);
 124             cur_mod.macros.push((def, None));
 125         }
 126         self.cx.cache.exact_paths = self.exact_paths;
 127         top_level_module
 128     }
 129
 130     fn visit_mod_contents(
 131         &mut self,
 132         span: Span,
 133         vis: &hir::Visibility<'_>,
 134         id: hir::HirId,
 135         m: &'tcx hir::Mod<'tcx>,
 136         name: Symbol,
 137     ) -> Module<'tcx> {
 138         let mut om = Module::new(name);
 139         om.where_outer = span;
 140         om.where_inner = m.inner;
 141         om.id = id;
 142         // Keep track of if there were any private modules in the path.
 143         let orig_inside_public_path = self.inside_public_path;
 144         self.inside_public_path &= vis.node.is_pub();
 145         for &i in m.item_ids {
 146             let item = self.cx.tcx.hir().item(i);
 147             self.visit_item(item, None, &mut om);
 148         }
 149         self.inside_public_path = orig_inside_public_path;
 150         om
 151     }
 152
 153     /// Tries to resolve the target of a `pub use` statement and inlines the
 154     /// target if it is defined locally and would not be documented otherwise,
 155     /// or when it is specifically requested with `please_inline`.
 156     /// (the latter is the case when the import is marked `doc(inline)`)
 157     ///
 158     /// Cross-crate inlining occurs later on during crate cleaning
 159     /// and follows different rules.
 160     ///
 161     /// Returns `true` if the target has been inlined.
 162     fn maybe_inline_local(
 163         &mut self,
 164         id: hir::HirId,
 165         res: Res,
 166         renamed: Option<Symbol>,
 167         glob: bool,
 168         om: &mut Module<'tcx>,
 169         please_inline: bool,
 170     ) -> bool {
 171         debug!("maybe_inline_local res: {:?}", res);
 172
 173         let tcx = self.cx.tcx;
 174         let res_did = if let Some(did) = res.opt_def_id() {
 175             did
 176         } else {
 177             return false;
 178         };
 179
 180         let use_attrs = tcx.hir().attrs(id);
 181         // Don't inline `doc(hidden)` imports so they can be stripped at a later stage.
 182         let is_no_inline = use_attrs.lists(sym::doc).has_word(sym::no_inline)
 183             || use_attrs.lists(sym::doc).has_word(sym::hidden);
 184
 185         // For cross-crate impl inlining we need to know whether items are
 186         // reachable in documentation -- a previously unreachable item can be
 187         // made reachable by cross-crate inlining which we're checking here.
 188         // (this is done here because we need to know this upfront).
 189         if !res_did.is_local() && !is_no_inline {
 190             let attrs = clean::inline::load_attrs(self.cx, res_did);
 191             let self_is_hidden = attrs.lists(sym::doc).has_word(sym::hidden);
 192             if !self_is_hidden {
 193                 if let Res::Def(kind, did) = res {
 194                     if kind == DefKind::Mod {
 195                         crate::visit_lib::LibEmbargoVisitor::new(self.cx).visit_mod(did)
 196                     } else {
 197                         // All items need to be handled here in case someone wishes to link
 198                         // to them with intra-doc links
 199                         self.cx.cache.access_levels.map.insert(did, AccessLevel::Public);
 200                     }
 201                 }
 202             }
 203             return false;
 204         }
 205
 206         let res_hir_id = match res_did.as_local() {
 207             Some(n) => tcx.hir().local_def_id_to_hir_id(n),
 208             None => return false,
 209         };
 210
 211         let is_private = !self.cx.cache.access_levels.is_public(res_did);
 212         let is_hidden = inherits_doc_hidden(self.cx.tcx, res_hir_id);
 213
 214         // Only inline if requested or if the item would otherwise be stripped.
 215         if (!please_inline && !is_private && !is_hidden) || is_no_inline {
 216             return false;
 217         }
 218
 219         if !self.view_item_stack.insert(res_hir_id) {
 220             return false;
 221         }
 222
 223         let ret = match tcx.hir().get(res_hir_id) {
 224             Node::Item(&hir::Item { kind: hir::ItemKind::Mod(ref m), .. }) if glob => {
 225                 let prev = mem::replace(&mut self.inlining, true);
 226                 for &i in m.item_ids {
 227                     let i = self.cx.tcx.hir().item(i);
 228                     self.visit_item(i, None, om);
 229                 }
 230                 self.inlining = prev;
 231                 true
 232             }
 233             Node::Item(it) if !glob => {
 234                 let prev = mem::replace(&mut self.inlining, true);
 235                 self.visit_item(it, renamed, om);
 236                 self.inlining = prev;
 237                 true
 238             }
 239             Node::ForeignItem(it) if !glob => {
 240                 let prev = mem::replace(&mut self.inlining, true);
 241                 self.visit_foreign_item(it, renamed, om);
 242                 self.inlining = prev;
 243                 true
 244             }
 245             Node::MacroDef(def) if !glob => {
 246                 om.macros.push((def, renamed));
 247                 true
 248             }
 249             _ => false,
 250         };
 251         self.view_item_stack.remove(&res_hir_id);
 252         ret
 253     }
 254
 255     fn visit_item(
 256         &mut self,
 257         item: &'tcx hir::Item<'_>,
 258         renamed: Option<Symbol>,
 259         om: &mut Module<'tcx>,
 260     ) {
 261         debug!("visiting item {:?}", item);
 262         let name = renamed.unwrap_or(item.ident.name);
 263
 264         if item.vis.node.is_pub() {
 265             self.store_path(item.def_id.to_def_id());
 266         }
 267
 268         match item.kind {
 269             hir::ItemKind::ForeignMod { items, .. } => {
 270                 for item in items {
 271                     let item = self.cx.tcx.hir().foreign_item(item.id);
 272                     self.visit_foreign_item(item, None, om);
 273                 }
 274             }
 275             // If we're inlining, skip private items.
 276             _ if self.inlining && !item.vis.node.is_pub() => {}
 277             hir::ItemKind::GlobalAsm(..) => {}
 278             hir::ItemKind::Use(_, hir::UseKind::ListStem) => {}
 279             hir::ItemKind::Use(ref path, kind) => {
 280                 let is_glob = kind == hir::UseKind::Glob;
 281
 282                 // Struct and variant constructors and proc macro stubs always show up alongside
 283                 // their definitions, we've already processed them so just discard these.
 284                 if let Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) = path.res {
 285                     return;
 286                 }
 287
 288                 let attrs = self.cx.tcx.hir().attrs(item.hir_id());
 289
 290                 // If there was a private module in the current path then don't bother inlining
 291                 // anything as it will probably be stripped anyway.
 292                 if item.vis.node.is_pub() && self.inside_public_path {
 293                     let please_inline = attrs.iter().any(|item| match item.meta_item_list() {
 294                         Some(ref list) if item.has_name(sym::doc) => {
 295                             list.iter().any(|i| i.has_name(sym::inline))
 296                         }
 297                         _ => false,
 298                     });
 299                     let ident = if is_glob { None } else { Some(name) };
 300                     if self.maybe_inline_local(
 301                         item.hir_id(),
 302                         path.res,
 303                         ident,
 304                         is_glob,
 305                         om,
 306                         please_inline,
 307                     ) {
 308                         return;
 309                     }
 310                 }
 311
 312                 om.items.push((item, renamed))
 313             }
 314             hir::ItemKind::Mod(ref m) => {
 315                 om.mods.push(self.visit_mod_contents(item.span, &item.vis, item.hir_id(), m, name));
 316             }
 317             hir::ItemKind::Fn(..)
 318             | hir::ItemKind::ExternCrate(..)
 319             | hir::ItemKind::Enum(..)
 320             | hir::ItemKind::Struct(..)
 321             | hir::ItemKind::Union(..)
 322             | hir::ItemKind::TyAlias(..)
 323             | hir::ItemKind::OpaqueTy(..)
 324             | hir::ItemKind::Static(..)
 325             | hir::ItemKind::Trait(..)
 326             | hir::ItemKind::TraitAlias(..) => om.items.push((item, renamed)),
 327             hir::ItemKind::Const(..) => {
 328                 // Underscore constants do not correspond to a nameable item and
 329                 // so are never useful in documentation.
 330                 if name != kw::Underscore {
 331                     om.items.push((item, renamed));
 332                 }
 333             }
 334             hir::ItemKind::Impl(ref impl_) => {
 335                 // Don't duplicate impls when inlining or if it's implementing a trait, we'll pick
 336                 // them up regardless of where they're located.
 337                 if !self.inlining && impl_.of_trait.is_none() {
 338                     om.items.push((item, None));
 339                 }
 340             }
 341         }
 342     }
 343
 344     fn visit_foreign_item(
 345         &mut self,
 346         item: &'tcx hir::ForeignItem<'_>,
 347         renamed: Option<Symbol>,
 348         om: &mut Module<'tcx>,
 349     ) {
 350         // If inlining we only want to include public functions.
 351         if !self.inlining || item.vis.node.is_pub() {
 352             om.foreigns.push((item, renamed));
 353         }
 354     }
 355 }