1 //! For each definition, we track the following data. A definition
2 //! here is defined somewhat circularly as "something with a `DefId`",
3 //! but it generally corresponds to things like structs, enums, etc.
4 //! There are also some rather random cases (like const initializer
5 //! expressions) that are mostly just leftovers.
7 pub use crate::def_id::DefPathHash;
8 use crate::def_id::{CrateNum, DefIndex, LocalDefId, StableCrateId, CRATE_DEF_INDEX, LOCAL_CRATE};
9 use crate::def_path_hash_map::DefPathHashMap;
11 use rustc_data_structures::fx::FxHashMap;
12 use rustc_data_structures::stable_hasher::StableHasher;
13 use rustc_index::vec::IndexVec;
14 use rustc_span::hygiene::ExpnId;
15 use rustc_span::symbol::{kw, sym, Symbol};
18 use std::fmt::{self, Write};
22 /// The `DefPathTable` maps `DefIndex`es to `DefKey`s and vice versa.
23 /// Internally the `DefPathTable` holds a tree of `DefKey`s, where each `DefKey`
24 /// stores the `DefIndex` of its parent.
25 /// There is one `DefPathTable` for each crate.
26 #[derive(Clone, Default, Debug)]
27 pub struct DefPathTable {
28 index_to_key: IndexVec<DefIndex, DefKey>,
29 def_path_hashes: IndexVec<DefIndex, DefPathHash>,
30 def_path_hash_to_index: DefPathHashMap,
34 fn allocate(&mut self, key: DefKey, def_path_hash: DefPathHash) -> DefIndex {
36 let index = DefIndex::from(self.index_to_key.len());
37 debug!("DefPathTable::insert() - {:?} <-> {:?}", key, index);
38 self.index_to_key.push(key);
41 self.def_path_hashes.push(def_path_hash);
42 debug_assert!(self.def_path_hashes.len() == self.index_to_key.len());
44 // Check for hash collisions of DefPathHashes. These should be
46 if let Some(existing) = self.def_path_hash_to_index.insert(&def_path_hash, &index) {
47 let def_path1 = DefPath::make(LOCAL_CRATE, existing, |idx| self.def_key(idx));
48 let def_path2 = DefPath::make(LOCAL_CRATE, index, |idx| self.def_key(idx));
50 // Continuing with colliding DefPathHashes can lead to correctness
51 // issues. We must abort compilation.
53 // The likelihood of such a collision is very small, so actually
54 // running into one could be indicative of a poor hash function
57 // See the documentation for DefPathHash for more information.
59 "found DefPathHash collision between {:?} and {:?}. \
60 Compilation cannot continue.",
65 // Assert that all DefPathHashes correctly contain the local crate's
67 #[cfg(debug_assertions)]
68 if let Some(root) = self.def_path_hashes.get(CRATE_DEF_INDEX) {
69 assert!(def_path_hash.stable_crate_id() == root.stable_crate_id());
76 pub fn def_key(&self, index: DefIndex) -> DefKey {
77 self.index_to_key[index]
81 pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
82 let hash = self.def_path_hashes[index];
83 debug!("def_path_hash({:?}) = {:?}", index, hash);
87 pub fn enumerated_keys_and_path_hashes(
89 ) -> impl Iterator<Item = (DefIndex, &DefKey, &DefPathHash)> + ExactSizeIterator + '_ {
92 .map(move |(index, key)| (index, key, &self.def_path_hashes[index]))
96 /// The definition table containing node definitions.
97 /// It holds the `DefPathTable` for `LocalDefId`s/`DefPath`s.
98 /// It also stores mappings to convert `LocalDefId`s to/from `HirId`s.
99 #[derive(Clone, Debug)]
100 pub struct Definitions {
102 next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>,
104 /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
105 expansions_that_defined: FxHashMap<LocalDefId, ExpnId>,
107 def_id_to_span: IndexVec<LocalDefId, Span>,
109 /// The [StableCrateId] of the local crate.
110 stable_crate_id: StableCrateId,
113 /// A unique identifier that we can use to lookup a definition
114 /// precisely. It combines the index of the definition's parent (if
115 /// any) with a `DisambiguatedDefPathData`.
116 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
119 pub parent: Option<DefIndex>,
121 /// The identifier of this node.
122 pub disambiguated_data: DisambiguatedDefPathData,
126 pub(crate) fn compute_stable_hash(&self, parent: DefPathHash) -> DefPathHash {
127 let mut hasher = StableHasher::new();
129 parent.hash(&mut hasher);
131 let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
133 std::mem::discriminant(data).hash(&mut hasher);
134 if let Some(name) = data.get_opt_name() {
135 // Get a stable hash by considering the symbol chars rather than
137 name.as_str().hash(&mut hasher);
140 disambiguator.hash(&mut hasher);
142 let local_hash: u64 = hasher.finish();
144 // Construct the new DefPathHash, making sure that the `crate_id`
145 // portion of the hash is properly copied from the parent. This way the
146 // `crate_id` part will be recursively propagated from the root to all
147 // DefPathHashes in this DefPathTable.
148 DefPathHash::new(parent.stable_crate_id(), local_hash)
152 pub fn get_opt_name(&self) -> Option<Symbol> {
153 self.disambiguated_data.data.get_opt_name()
157 /// A pair of `DefPathData` and an integer disambiguator. The integer is
158 /// normally `0`, but in the event that there are multiple defs with the
159 /// same `parent` and `data`, we use this field to disambiguate
160 /// between them. This introduces some artificial ordering dependency
161 /// but means that if you have, e.g., two impls for the same type in
162 /// the same module, they do get distinct `DefId`s.
163 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
164 pub struct DisambiguatedDefPathData {
165 pub data: DefPathData,
166 pub disambiguator: u32,
169 impl DisambiguatedDefPathData {
170 pub fn fmt_maybe_verbose(&self, writer: &mut impl Write, verbose: bool) -> fmt::Result {
171 match self.data.name() {
172 DefPathDataName::Named(name) => {
173 if verbose && self.disambiguator != 0 {
174 write!(writer, "{}#{}", name, self.disambiguator)
176 writer.write_str(name.as_str())
179 DefPathDataName::Anon { namespace } => {
180 write!(writer, "{{{}#{}}}", namespace, self.disambiguator)
186 impl fmt::Display for DisambiguatedDefPathData {
187 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
188 self.fmt_maybe_verbose(f, true)
192 #[derive(Clone, Debug, Encodable, Decodable)]
194 /// The path leading from the crate root to the item.
195 pub data: Vec<DisambiguatedDefPathData>,
197 /// The crate root this path is relative to.
202 pub fn make<FN>(krate: CrateNum, start_index: DefIndex, mut get_key: FN) -> DefPath
204 FN: FnMut(DefIndex) -> DefKey,
206 let mut data = vec![];
207 let mut index = Some(start_index);
209 debug!("DefPath::make: krate={:?} index={:?}", krate, index);
210 let p = index.unwrap();
211 let key = get_key(p);
212 debug!("DefPath::make: key={:?}", key);
213 match key.disambiguated_data.data {
214 DefPathData::CrateRoot => {
215 assert!(key.parent.is_none());
219 data.push(key.disambiguated_data);
225 DefPath { data, krate }
228 /// Returns a string representation of the `DefPath` without
229 /// the crate-prefix. This method is useful if you don't have
230 /// a `TyCtxt` available.
231 pub fn to_string_no_crate_verbose(&self) -> String {
232 let mut s = String::with_capacity(self.data.len() * 16);
234 for component in &self.data {
235 write!(s, "::{}", component).unwrap();
241 /// Returns a filename-friendly string of the `DefPath`, without
242 /// the crate-prefix. This method is useful if you don't have
243 /// a `TyCtxt` available.
244 pub fn to_filename_friendly_no_crate(&self) -> String {
245 let mut s = String::with_capacity(self.data.len() * 16);
247 let mut opt_delimiter = None;
248 for component in &self.data {
249 s.extend(opt_delimiter);
250 opt_delimiter = Some('-');
251 write!(s, "{}", component).unwrap();
258 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
259 pub enum DefPathData {
260 // Root: these should only be used for the root nodes, because
261 // they are treated specially by the `def_path` function.
262 /// The crate root (marker).
264 // Catch-all for random `DefId` things like `DUMMY_NODE_ID`.
267 // Different kinds of items and item-like things:
270 /// An `extern` block.
272 /// Something in the type namespace.
274 /// Something in the value namespace.
276 /// Something in the macro namespace.
278 /// Something in the lifetime namespace.
280 /// A closure expression.
283 // Subportions of items:
284 /// Implicit constructor for a unit or tuple-like struct or enum variant.
286 /// A constant expression (see `{ast,hir}::AnonConst`).
288 /// An `impl Trait` type node.
293 pub fn def_path_table(&self) -> &DefPathTable {
297 /// Gets the number of definitions.
298 pub fn def_index_count(&self) -> usize {
299 self.table.index_to_key.len()
303 pub fn def_key(&self, id: LocalDefId) -> DefKey {
304 self.table.def_key(id.local_def_index)
308 pub fn def_path_hash(&self, id: LocalDefId) -> DefPathHash {
309 self.table.def_path_hash(id.local_def_index)
312 /// Returns the path from the crate root to `index`. The root
313 /// nodes are not included in the path (i.e., this will be an
314 /// empty vector for the crate root). For an inlined item, this
315 /// will be the path of the item in the external crate (but the
316 /// path will begin with the path to the external crate).
317 pub fn def_path(&self, id: LocalDefId) -> DefPath {
318 DefPath::make(LOCAL_CRATE, id.local_def_index, |index| {
319 self.def_key(LocalDefId { local_def_index: index })
323 /// Adds a root definition (no parent) and a few other reserved definitions.
324 pub fn new(stable_crate_id: StableCrateId, crate_span: Span) -> Definitions {
327 disambiguated_data: DisambiguatedDefPathData {
328 data: DefPathData::CrateRoot,
333 let parent_hash = DefPathHash::new(stable_crate_id, 0);
334 let def_path_hash = key.compute_stable_hash(parent_hash);
336 // Create the root definition.
337 let mut table = DefPathTable::default();
338 let root = LocalDefId { local_def_index: table.allocate(key, def_path_hash) };
339 assert_eq!(root.local_def_index, CRATE_DEF_INDEX);
341 let mut def_id_to_span = IndexVec::new();
342 // A relative span's parent must be an absolute span.
343 debug_assert_eq!(crate_span.data_untracked().parent, None);
344 let _root = def_id_to_span.push(crate_span);
345 debug_assert_eq!(_root, root);
349 next_disambiguator: Default::default(),
350 expansions_that_defined: Default::default(),
356 /// Retrieves the root definition.
357 pub fn get_root_def(&self) -> LocalDefId {
358 LocalDefId { local_def_index: CRATE_DEF_INDEX }
361 /// Adds a definition with a parent definition.
369 debug!("create_def(parent={:?}, data={:?}, expn_id={:?})", parent, data, expn_id);
371 // The root node must be created with `create_root_def()`.
372 assert!(data != DefPathData::CrateRoot);
374 // Find the next free disambiguator for this key.
375 let disambiguator = {
376 let next_disamb = self.next_disambiguator.entry((parent, data)).or_insert(0);
377 let disambiguator = *next_disamb;
378 *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
382 parent: Some(parent.local_def_index),
383 disambiguated_data: DisambiguatedDefPathData { data, disambiguator },
386 let parent_hash = self.table.def_path_hash(parent.local_def_index);
387 let def_path_hash = key.compute_stable_hash(parent_hash);
389 debug!("create_def: after disambiguation, key = {:?}", key);
391 // Create the definition.
392 let def_id = LocalDefId { local_def_index: self.table.allocate(key, def_path_hash) };
394 if expn_id != ExpnId::root() {
395 self.expansions_that_defined.insert(def_id, expn_id);
398 // A relative span's parent must be an absolute span.
399 debug_assert_eq!(span.data_untracked().parent, None);
400 let _id = self.def_id_to_span.push(span);
401 debug_assert_eq!(_id, def_id);
406 pub fn expansion_that_defined(&self, id: LocalDefId) -> ExpnId {
407 self.expansions_that_defined.get(&id).copied().unwrap_or_else(ExpnId::root)
410 /// Retrieves the span of the given `DefId` if `DefId` is in the local crate.
412 pub fn def_span(&self, def_id: LocalDefId) -> Span {
413 self.def_id_to_span[def_id]
416 pub fn iter_local_def_id(&self) -> impl Iterator<Item = LocalDefId> + '_ {
417 self.table.def_path_hashes.indices().map(|local_def_index| LocalDefId { local_def_index })
421 pub fn local_def_path_hash_to_def_id(
424 err: &mut dyn FnMut() -> !,
426 debug_assert!(hash.stable_crate_id() == self.stable_crate_id);
428 .def_path_hash_to_index
430 .map(|local_def_index| LocalDefId { local_def_index })
431 .unwrap_or_else(|| err())
434 pub fn def_path_hash_to_def_index_map(&self) -> &DefPathHashMap {
435 &self.table.def_path_hash_to_index
439 #[derive(Copy, Clone, PartialEq, Debug)]
440 pub enum DefPathDataName {
442 Anon { namespace: Symbol },
446 pub fn get_opt_name(&self) -> Option<Symbol> {
447 use self::DefPathData::*;
449 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
451 Impl | ForeignMod | CrateRoot | Misc | ClosureExpr | Ctor | AnonConst | ImplTrait => {
457 pub fn name(&self) -> DefPathDataName {
458 use self::DefPathData::*;
460 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => {
461 DefPathDataName::Named(name)
463 // Note that this does not show up in user print-outs.
464 CrateRoot => DefPathDataName::Anon { namespace: kw::Crate },
465 Impl => DefPathDataName::Anon { namespace: kw::Impl },
466 ForeignMod => DefPathDataName::Anon { namespace: kw::Extern },
467 Misc => DefPathDataName::Anon { namespace: sym::misc },
468 ClosureExpr => DefPathDataName::Anon { namespace: sym::closure },
469 Ctor => DefPathDataName::Anon { namespace: sym::constructor },
470 AnonConst => DefPathDataName::Anon { namespace: sym::constant },
471 ImplTrait => DefPathDataName::Anon { namespace: sym::opaque },
476 impl fmt::Display for DefPathData {
477 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
479 DefPathDataName::Named(name) => f.write_str(name.as_str()),
480 // FIXME(#70334): this will generate legacy {{closure}}, {{impl}}, etc
481 DefPathDataName::Anon { namespace } => write!(f, "{{{{{}}}}}", namespace),