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};
11 use rustc_data_structures::fx::FxHashMap;
12 use rustc_data_structures::stable_hasher::StableHasher;
13 use rustc_data_structures::unhash::UnhashMap;
14 use rustc_index::vec::IndexVec;
15 use rustc_span::crate_disambiguator::CrateDisambiguator;
16 use rustc_span::hygiene::ExpnId;
17 use rustc_span::symbol::{kw, sym, Symbol};
19 use std::fmt::{self, Write};
23 /// The `DefPathTable` maps `DefIndex`es to `DefKey`s and vice versa.
24 /// Internally the `DefPathTable` holds a tree of `DefKey`s, where each `DefKey`
25 /// stores the `DefIndex` of its parent.
26 /// There is one `DefPathTable` for each crate.
27 #[derive(Clone, Default)]
28 pub struct DefPathTable {
29 index_to_key: IndexVec<DefIndex, DefKey>,
30 def_path_hashes: IndexVec<DefIndex, DefPathHash>,
31 def_path_hash_to_index: UnhashMap<DefPathHash, DefIndex>,
35 fn allocate(&mut self, key: DefKey, def_path_hash: DefPathHash) -> DefIndex {
37 let index = DefIndex::from(self.index_to_key.len());
38 debug!("DefPathTable::insert() - {:?} <-> {:?}", key, index);
39 self.index_to_key.push(key);
42 self.def_path_hashes.push(def_path_hash);
43 debug_assert!(self.def_path_hashes.len() == self.index_to_key.len());
45 // Check for hash collisions of DefPathHashes. These should be
47 if let Some(existing) = self.def_path_hash_to_index.insert(def_path_hash, index) {
48 let def_path1 = DefPath::make(LOCAL_CRATE, existing, |idx| self.def_key(idx));
49 let def_path2 = DefPath::make(LOCAL_CRATE, index, |idx| self.def_key(idx));
51 // Continuing with colliding DefPathHashes can lead to correctness
52 // issues. We must abort compilation.
54 // The likelyhood of such a collision is very small, so actually
55 // running into one could be indicative of a poor hash function
58 // See the documentation for DefPathHash for more information.
60 "found DefPathHash collsion between {:?} and {:?}. \
61 Compilation cannot continue.",
66 // Assert that all DefPathHashes correctly contain the local crate's
68 #[cfg(debug_assertions)]
69 if let Some(root) = self.def_path_hashes.get(CRATE_DEF_INDEX) {
70 assert!(def_path_hash.stable_crate_id() == root.stable_crate_id());
77 pub fn def_key(&self, index: DefIndex) -> DefKey {
78 self.index_to_key[index]
82 pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
83 let hash = self.def_path_hashes[index];
84 debug!("def_path_hash({:?}) = {:?}", index, hash);
88 pub fn enumerated_keys_and_path_hashes(
90 ) -> impl Iterator<Item = (DefIndex, &DefKey, &DefPathHash)> + '_ {
93 .map(move |(index, key)| (index, key, &self.def_path_hashes[index]))
97 /// The definition table containing node definitions.
98 /// It holds the `DefPathTable` for `LocalDefId`s/`DefPath`s.
99 /// It also stores mappings to convert `LocalDefId`s to/from `HirId`s.
101 pub struct Definitions {
104 // FIXME(eddyb) ideally all `LocalDefId`s would be HIR owners.
105 pub(super) def_id_to_hir_id: IndexVec<LocalDefId, Option<hir::HirId>>,
106 /// The reverse mapping of `def_id_to_hir_id`.
107 pub(super) hir_id_to_def_id: FxHashMap<hir::HirId, LocalDefId>,
109 /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
110 expansions_that_defined: FxHashMap<LocalDefId, ExpnId>,
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 /// A pair of `DefPathData` and an integer disambiguator. The integer is
153 /// normally `0`, but in the event that there are multiple defs with the
154 /// same `parent` and `data`, we use this field to disambiguate
155 /// between them. This introduces some artificial ordering dependency
156 /// but means that if you have, e.g., two impls for the same type in
157 /// the same module, they do get distinct `DefId`s.
158 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
159 pub struct DisambiguatedDefPathData {
160 pub data: DefPathData,
161 pub disambiguator: u32,
164 impl DisambiguatedDefPathData {
165 pub fn fmt_maybe_verbose(&self, writer: &mut impl Write, verbose: bool) -> fmt::Result {
166 match self.data.name() {
167 DefPathDataName::Named(name) => {
168 if verbose && self.disambiguator != 0 {
169 write!(writer, "{}#{}", name, self.disambiguator)
171 writer.write_str(&name.as_str())
174 DefPathDataName::Anon { namespace } => {
175 write!(writer, "{{{}#{}}}", namespace, self.disambiguator)
181 impl fmt::Display for DisambiguatedDefPathData {
182 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
183 self.fmt_maybe_verbose(f, true)
187 #[derive(Clone, Debug, Encodable, Decodable)]
189 /// The path leading from the crate root to the item.
190 pub data: Vec<DisambiguatedDefPathData>,
192 /// The crate root this path is relative to.
197 pub fn make<FN>(krate: CrateNum, start_index: DefIndex, mut get_key: FN) -> DefPath
199 FN: FnMut(DefIndex) -> DefKey,
201 let mut data = vec![];
202 let mut index = Some(start_index);
204 debug!("DefPath::make: krate={:?} index={:?}", krate, index);
205 let p = index.unwrap();
206 let key = get_key(p);
207 debug!("DefPath::make: key={:?}", key);
208 match key.disambiguated_data.data {
209 DefPathData::CrateRoot => {
210 assert!(key.parent.is_none());
214 data.push(key.disambiguated_data);
220 DefPath { data, krate }
223 /// Returns a string representation of the `DefPath` without
224 /// the crate-prefix. This method is useful if you don't have
225 /// a `TyCtxt` available.
226 pub fn to_string_no_crate_verbose(&self) -> String {
227 let mut s = String::with_capacity(self.data.len() * 16);
229 for component in &self.data {
230 write!(s, "::{}", component).unwrap();
236 /// Returns a filename-friendly string of the `DefPath`, without
237 /// the crate-prefix. This method is useful if you don't have
238 /// a `TyCtxt` available.
239 pub fn to_filename_friendly_no_crate(&self) -> String {
240 let mut s = String::with_capacity(self.data.len() * 16);
242 let mut opt_delimiter = None;
243 for component in &self.data {
244 s.extend(opt_delimiter);
245 opt_delimiter = Some('-');
246 write!(s, "{}", component).unwrap();
253 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
254 pub enum DefPathData {
255 // Root: these should only be used for the root nodes, because
256 // they are treated specially by the `def_path` function.
257 /// The crate root (marker).
259 // Catch-all for random `DefId` things like `DUMMY_NODE_ID`.
262 // Different kinds of items and item-like things:
265 /// Something in the type namespace.
267 /// Something in the value namespace.
269 /// Something in the macro namespace.
271 /// Something in the lifetime namespace.
273 /// A closure expression.
276 // Subportions of items:
277 /// Implicit constructor for a unit or tuple-like struct or enum variant.
279 /// A constant expression (see `{ast,hir}::AnonConst`).
281 /// An `impl Trait` type node.
286 pub fn def_path_table(&self) -> &DefPathTable {
290 /// Gets the number of definitions.
291 pub fn def_index_count(&self) -> usize {
292 self.table.index_to_key.len()
296 pub fn def_key(&self, id: LocalDefId) -> DefKey {
297 self.table.def_key(id.local_def_index)
301 pub fn def_path_hash(&self, id: LocalDefId) -> DefPathHash {
302 self.table.def_path_hash(id.local_def_index)
305 /// Returns the path from the crate root to `index`. The root
306 /// nodes are not included in the path (i.e., this will be an
307 /// empty vector for the crate root). For an inlined item, this
308 /// will be the path of the item in the external crate (but the
309 /// path will begin with the path to the external crate).
310 pub fn def_path(&self, id: LocalDefId) -> DefPath {
311 DefPath::make(LOCAL_CRATE, id.local_def_index, |index| {
312 self.def_key(LocalDefId { local_def_index: index })
318 pub fn local_def_id_to_hir_id(&self, id: LocalDefId) -> hir::HirId {
319 self.def_id_to_hir_id[id].unwrap()
323 pub fn opt_hir_id_to_local_def_id(&self, hir_id: hir::HirId) -> Option<LocalDefId> {
324 self.hir_id_to_def_id.get(&hir_id).copied()
327 /// Adds a root definition (no parent) and a few other reserved definitions.
328 pub fn new(crate_name: &str, crate_disambiguator: CrateDisambiguator) -> Definitions {
331 disambiguated_data: DisambiguatedDefPathData {
332 data: DefPathData::CrateRoot,
337 let stable_crate_id = StableCrateId::new(crate_name, crate_disambiguator);
338 let parent_hash = DefPathHash::new(stable_crate_id, 0);
339 let def_path_hash = key.compute_stable_hash(parent_hash);
341 // Create the root definition.
342 let mut table = DefPathTable::default();
343 let root = LocalDefId { local_def_index: table.allocate(key, def_path_hash) };
344 assert_eq!(root.local_def_index, CRATE_DEF_INDEX);
348 def_id_to_hir_id: Default::default(),
349 hir_id_to_def_id: Default::default(),
350 expansions_that_defined: Default::default(),
354 /// Retrieves the root definition.
355 pub fn get_root_def(&self) -> LocalDefId {
356 LocalDefId { local_def_index: CRATE_DEF_INDEX }
359 /// Adds a definition with a parent definition.
365 mut next_disambiguator: impl FnMut(LocalDefId, DefPathData) -> u32,
367 debug!("create_def(parent={:?}, data={:?}, expn_id={:?})", parent, data, expn_id);
369 // The root node must be created with `create_root_def()`.
370 assert!(data != DefPathData::CrateRoot);
372 let disambiguator = next_disambiguator(parent, data);
374 parent: Some(parent.local_def_index),
375 disambiguated_data: DisambiguatedDefPathData { data, disambiguator },
378 let parent_hash = self.table.def_path_hash(parent.local_def_index);
379 let def_path_hash = key.compute_stable_hash(parent_hash);
381 debug!("create_def: after disambiguation, key = {:?}", key);
383 // Create the definition.
384 let def_id = LocalDefId { local_def_index: self.table.allocate(key, def_path_hash) };
386 if expn_id != ExpnId::root() {
387 self.expansions_that_defined.insert(def_id, expn_id);
393 /// Initializes the `LocalDefId` to `HirId` mapping once it has been generated during
394 /// AST to HIR lowering.
395 pub fn init_def_id_to_hir_id_mapping(
397 mapping: IndexVec<LocalDefId, Option<hir::HirId>>,
400 self.def_id_to_hir_id.is_empty(),
401 "trying to initialize `LocalDefId` <-> `HirId` mappings twice"
404 // Build the reverse mapping of `def_id_to_hir_id`.
405 self.hir_id_to_def_id = mapping
407 .filter_map(|(def_id, hir_id)| hir_id.map(|hir_id| (hir_id, def_id)))
410 self.def_id_to_hir_id = mapping;
413 pub fn expansion_that_defined(&self, id: LocalDefId) -> ExpnId {
414 self.expansions_that_defined.get(&id).copied().unwrap_or_else(ExpnId::root)
417 pub fn iter_local_def_id(&self) -> impl Iterator<Item = LocalDefId> + '_ {
418 self.def_id_to_hir_id.iter_enumerated().map(|(k, _)| k)
422 pub fn local_def_path_hash_to_def_id(&self, hash: DefPathHash) -> Option<LocalDefId> {
424 .def_path_hash_to_index
426 .map(|&local_def_index| LocalDefId { local_def_index })
430 #[derive(Copy, Clone, PartialEq, Debug)]
431 pub enum DefPathDataName {
433 Anon { namespace: Symbol },
437 pub fn get_opt_name(&self) -> Option<Symbol> {
438 use self::DefPathData::*;
440 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
442 Impl | CrateRoot | Misc | ClosureExpr | Ctor | AnonConst | ImplTrait => None,
446 pub fn name(&self) -> DefPathDataName {
447 use self::DefPathData::*;
449 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => {
450 DefPathDataName::Named(name)
452 // Note that this does not show up in user print-outs.
453 CrateRoot => DefPathDataName::Anon { namespace: kw::Crate },
454 Impl => DefPathDataName::Anon { namespace: kw::Impl },
455 Misc => DefPathDataName::Anon { namespace: sym::misc },
456 ClosureExpr => DefPathDataName::Anon { namespace: sym::closure },
457 Ctor => DefPathDataName::Anon { namespace: sym::constructor },
458 AnonConst => DefPathDataName::Anon { namespace: sym::constant },
459 ImplTrait => DefPathDataName::Anon { namespace: sym::opaque },
464 impl fmt::Display for DefPathData {
465 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
467 DefPathDataName::Named(name) => f.write_str(&name.as_str()),
468 // FIXME(#70334): this will generate legacy {{closure}}, {{impl}}, etc
469 DefPathDataName::Anon { namespace } => write!(f, "{{{{{}}}}}", namespace),