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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 crate struct Module<'hir> {
25 crate name: Symbol,
26 crate where_inner: Span,
27 crate mods: Vec<Module<'hir>>,
28 crate id: hir::HirId,
29 // (item, renamed)
30 crate items: Vec<(&'hir hir::Item<'hir>, Option<Symbol>)>,
31 crate foreigns: Vec<(&'hir hir::ForeignItem<'hir>, Option<Symbol>)>,
32 }
33
34 impl Module<'_> {
35 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 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 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 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 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 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([Cfg::Cfg(sym::test, None)].into_iter())
145 .collect();
146
147 self.cx.cache.exact_paths = self.exact_paths;
148 top_level_module
149 }
150
151 fn visit_mod_contents(
152 &mut self,
153 id: hir::HirId,
154 m: &'tcx hir::Mod<'tcx>,
155 name: Symbol,
156 ) -> Module<'tcx> {
157 let mut om = Module::new(name, id, m.inner);
158 let def_id = self.cx.tcx.hir().local_def_id(id).to_def_id();
159 // Keep track of if there were any private modules in the path.
160 let orig_inside_public_path = self.inside_public_path;
161 self.inside_public_path &= self.cx.tcx.visibility(def_id).is_public();
162 for &i in m.item_ids {
163 let item = self.cx.tcx.hir().item(i);
164 self.visit_item(item, None, &mut om);
165 }
166 self.inside_public_path = orig_inside_public_path;
167 om
168 }
169
170 /// Tries to resolve the target of a `pub use` statement and inlines the
171 /// target if it is defined locally and would not be documented otherwise,
172 /// or when it is specifically requested with `please_inline`.
173 /// (the latter is the case when the import is marked `doc(inline)`)
174 ///
175 /// Cross-crate inlining occurs later on during crate cleaning
176 /// and follows different rules.
177 ///
178 /// Returns `true` if the target has been inlined.
179 fn maybe_inline_local(
180 &mut self,
181 id: hir::HirId,
182 res: Res,
183 renamed: Option<Symbol>,
184 glob: bool,
185 om: &mut Module<'tcx>,
186 please_inline: bool,
187 ) -> bool {
188 debug!("maybe_inline_local res: {:?}", res);
189
190 let tcx = self.cx.tcx;
191 let Some(res_did) = res.opt_def_id() else {
192 return false;
193 };
194
195 let use_attrs = tcx.hir().attrs(id);
196 // Don't inline `doc(hidden)` imports so they can be stripped at a later stage.
197 let is_no_inline = use_attrs.lists(sym::doc).has_word(sym::no_inline)
198 || use_attrs.lists(sym::doc).has_word(sym::hidden);
199
200 // For cross-crate impl inlining we need to know whether items are
201 // reachable in documentation -- a previously unreachable item can be
202 // made reachable by cross-crate inlining which we're checking here.
203 // (this is done here because we need to know this upfront).
204 if !res_did.is_local() && !is_no_inline {
205 let attrs = clean::inline::load_attrs(self.cx, res_did);
206 let self_is_hidden = attrs.lists(sym::doc).has_word(sym::hidden);
207 if !self_is_hidden {
208 if let Res::Def(kind, did) = res {
209 if kind == DefKind::Mod {
210 crate::visit_lib::LibEmbargoVisitor::new(self.cx).visit_mod(did)
211 } else {
212 // All items need to be handled here in case someone wishes to link
213 // to them with intra-doc links
214 self.cx.cache.access_levels.map.insert(did, AccessLevel::Public);
215 }
216 }
217 }
218 return false;
219 }
220
221 let res_hir_id = match res_did.as_local() {
222 Some(n) => tcx.hir().local_def_id_to_hir_id(n),
223 None => return false,
224 };
225
226 let is_private = !self.cx.cache.access_levels.is_public(res_did);
227 let is_hidden = inherits_doc_hidden(self.cx.tcx, res_hir_id);
228
229 // Only inline if requested or if the item would otherwise be stripped.
230 if (!please_inline && !is_private && !is_hidden) || is_no_inline {
231 return false;
232 }
233
234 if !self.view_item_stack.insert(res_hir_id) {
235 return false;
236 }
237
238 let ret = match tcx.hir().get(res_hir_id) {
239 Node::Item(&hir::Item { kind: hir::ItemKind::Mod(ref m), .. }) if glob => {
240 let prev = mem::replace(&mut self.inlining, true);
241 for &i in m.item_ids {
242 let i = self.cx.tcx.hir().item(i);
243 self.visit_item(i, None, om);
244 }
245 self.inlining = prev;
246 true
247 }
248 Node::Item(it) if !glob => {
249 let prev = mem::replace(&mut self.inlining, true);
250 self.visit_item(it, renamed, om);
251 self.inlining = prev;
252 true
253 }
254 Node::ForeignItem(it) if !glob => {
255 let prev = mem::replace(&mut self.inlining, true);
256 self.visit_foreign_item(it, renamed, om);
257 self.inlining = prev;
258 true
259 }
260 _ => false,
261 };
262 self.view_item_stack.remove(&res_hir_id);
263 ret
264 }
265
266 fn visit_item(
267 &mut self,
268 item: &'tcx hir::Item<'_>,
269 renamed: Option<Symbol>,
270 om: &mut Module<'tcx>,
271 ) {
272 debug!("visiting item {:?}", item);
273 let name = renamed.unwrap_or(item.ident.name);
274
275 let def_id = item.def_id.to_def_id();
276 let is_pub = self.cx.tcx.visibility(def_id).is_public();
277
278 if is_pub {
279 self.store_path(item.def_id.to_def_id());
280 }
281
282 match item.kind {
283 hir::ItemKind::ForeignMod { items, .. } => {
284 for item in items {
285 let item = self.cx.tcx.hir().foreign_item(item.id);
286 self.visit_foreign_item(item, None, om);
287 }
288 }
289 // If we're inlining, skip private items.
290 _ if self.inlining && !is_pub => {}
291 hir::ItemKind::GlobalAsm(..) => {}
292 hir::ItemKind::Use(_, hir::UseKind::ListStem) => {}
293 hir::ItemKind::Use(path, kind) => {
294 let is_glob = kind == hir::UseKind::Glob;
295
296 // Struct and variant constructors and proc macro stubs always show up alongside
297 // their definitions, we've already processed them so just discard these.
298 if let Res::Def(DefKind::Ctor(..), _) | Res::SelfCtor(..) = path.res {
299 return;
300 }
301
302 let attrs = self.cx.tcx.hir().attrs(item.hir_id());
303
304 // If there was a private module in the current path then don't bother inlining
305 // anything as it will probably be stripped anyway.
306 if is_pub && self.inside_public_path {
307 let please_inline = attrs.iter().any(|item| match item.meta_item_list() {
308 Some(ref list) if item.has_name(sym::doc) => {
309 list.iter().any(|i| i.has_name(sym::inline))
310 }
311 _ => false,
312 });
313 let ident = if is_glob { None } else { Some(name) };
314 if self.maybe_inline_local(
315 item.hir_id(),
316 path.res,
317 ident,
318 is_glob,
319 om,
320 please_inline,
321 ) {
322 return;
323 }
324 }
325
326 om.items.push((item, renamed))
327 }
328 hir::ItemKind::Macro(ref macro_def) => {
329 // `#[macro_export] macro_rules!` items are handled seperately in `visit()`,
330 // above, since they need to be documented at the module top level. Accordingly,
331 // we only want to handle macros if one of three conditions holds:
332 //
333 // 1. This macro was defined by `macro`, and thus isn't covered by the case
334 // above.
335 // 2. This macro isn't marked with `#[macro_export]`, and thus isn't covered
336 // by the case above.
337 // 3. We're inlining, since a reexport where inlining has been requested
338 // should be inlined even if it is also documented at the top level.
339
340 let def_id = item.def_id.to_def_id();
341 let is_macro_2_0 = !macro_def.macro_rules;
342 let nonexported = !self.cx.tcx.has_attr(def_id, sym::macro_export);
343
344 if is_macro_2_0 || nonexported || self.inlining {
345 om.items.push((item, renamed));
346 }
347 }
348 hir::ItemKind::Mod(ref m) => {
349 om.mods.push(self.visit_mod_contents(item.hir_id(), m, name));
350 }
351 hir::ItemKind::Fn(..)
352 | hir::ItemKind::ExternCrate(..)
353 | hir::ItemKind::Enum(..)
354 | hir::ItemKind::Struct(..)
355 | hir::ItemKind::Union(..)
356 | hir::ItemKind::TyAlias(..)
357 | hir::ItemKind::OpaqueTy(..)
358 | hir::ItemKind::Static(..)
359 | hir::ItemKind::Trait(..)
360 | hir::ItemKind::TraitAlias(..) => om.items.push((item, renamed)),
361 hir::ItemKind::Const(..) => {
362 // Underscore constants do not correspond to a nameable item and
363 // so are never useful in documentation.
364 if name != kw::Underscore {
365 om.items.push((item, renamed));
366 }
367 }
368 hir::ItemKind::Impl(ref impl_) => {
369 // Don't duplicate impls when inlining or if it's implementing a trait, we'll pick
370 // them up regardless of where they're located.
371 if !self.inlining && impl_.of_trait.is_none() {
372 om.items.push((item, None));
373 }
374 }
375 }
376 }
377
378 fn visit_foreign_item(
379 &mut self,
380 item: &'tcx hir::ForeignItem<'_>,
381 renamed: Option<Symbol>,
382 om: &mut Module<'tcx>,
383 ) {
384 // If inlining we only want to include public functions.
385 if !self.inlining || self.cx.tcx.visibility(item.def_id).is_public() {
386 om.foreigns.push((item, renamed));
387 }
388 }
389 }