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;
9 CrateNum, DefId, DefIndex, LocalDefId, StableCrateId, CRATE_DEF_INDEX, LOCAL_CRATE,
13 use rustc_data_structures::fx::FxHashMap;
14 use rustc_data_structures::stable_hasher::StableHasher;
15 use rustc_data_structures::unhash::UnhashMap;
16 use rustc_index::vec::IndexVec;
17 use rustc_span::crate_disambiguator::CrateDisambiguator;
18 use rustc_span::hygiene::ExpnId;
19 use rustc_span::symbol::{kw, sym, Symbol};
21 use std::fmt::{self, Write};
25 /// The `DefPathTable` maps `DefIndex`es to `DefKey`s and vice versa.
26 /// Internally the `DefPathTable` holds a tree of `DefKey`s, where each `DefKey`
27 /// stores the `DefIndex` of its parent.
28 /// There is one `DefPathTable` for each crate.
29 #[derive(Clone, Default)]
30 pub struct DefPathTable {
31 index_to_key: IndexVec<DefIndex, DefKey>,
32 def_path_hashes: IndexVec<DefIndex, DefPathHash>,
33 def_path_hash_to_index: UnhashMap<DefPathHash, DefIndex>,
37 fn allocate(&mut self, key: DefKey, def_path_hash: DefPathHash) -> DefIndex {
39 let index = DefIndex::from(self.index_to_key.len());
40 debug!("DefPathTable::insert() - {:?} <-> {:?}", key, index);
41 self.index_to_key.push(key);
44 self.def_path_hashes.push(def_path_hash);
45 debug_assert!(self.def_path_hashes.len() == self.index_to_key.len());
47 // Check for hash collisions of DefPathHashes. These should be
49 if let Some(existing) = self.def_path_hash_to_index.insert(def_path_hash, index) {
50 let def_path1 = DefPath::make(LOCAL_CRATE, existing, |idx| self.def_key(idx));
51 let def_path2 = DefPath::make(LOCAL_CRATE, index, |idx| self.def_key(idx));
53 // Continuing with colliding DefPathHashes can lead to correctness
54 // issues. We must abort compilation.
56 // The likelyhood of such a collision is very small, so actually
57 // running into one could be indicative of a poor hash function
60 // See the documentation for DefPathHash for more information.
62 "found DefPathHash collsion between {:?} and {:?}. \
63 Compilation cannot continue.",
68 // Assert that all DefPathHashes correctly contain the local crate's
70 #[cfg(debug_assertions)]
71 if let Some(root) = self.def_path_hashes.get(CRATE_DEF_INDEX) {
72 assert!(def_path_hash.stable_crate_id() == root.stable_crate_id());
79 pub fn def_key(&self, index: DefIndex) -> DefKey {
80 self.index_to_key[index]
84 pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
85 let hash = self.def_path_hashes[index];
86 debug!("def_path_hash({:?}) = {:?}", index, hash);
90 /// Used by librustdoc for fake DefIds.
91 pub fn num_def_ids(&self) -> usize {
92 self.index_to_key.len()
95 pub fn enumerated_keys_and_path_hashes(
97 ) -> impl Iterator<Item = (DefIndex, &DefKey, &DefPathHash)> + '_ {
100 .map(move |(index, key)| (index, key, &self.def_path_hashes[index]))
103 pub fn all_def_path_hashes_and_def_ids(
106 ) -> impl Iterator<Item = (DefPathHash, DefId)> + '_ {
109 .map(move |(index, hash)| (*hash, DefId { krate, index }))
113 /// The definition table containing node definitions.
114 /// It holds the `DefPathTable` for `LocalDefId`s/`DefPath`s.
115 /// It also stores mappings to convert `LocalDefId`s to/from `HirId`s.
117 pub struct Definitions {
120 // FIXME(eddyb) ideally all `LocalDefId`s would be HIR owners.
121 pub(super) def_id_to_hir_id: IndexVec<LocalDefId, Option<hir::HirId>>,
122 /// The reverse mapping of `def_id_to_hir_id`.
123 pub(super) hir_id_to_def_id: FxHashMap<hir::HirId, LocalDefId>,
125 /// If `ExpnId` is an ID of some macro expansion,
126 /// then `DefId` is the normal module (`mod`) in which the expanded macro was defined.
127 parent_modules_of_macro_defs: FxHashMap<ExpnId, DefId>,
128 /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
129 expansions_that_defined: FxHashMap<LocalDefId, ExpnId>,
132 /// A unique identifier that we can use to lookup a definition
133 /// precisely. It combines the index of the definition's parent (if
134 /// any) with a `DisambiguatedDefPathData`.
135 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
138 pub parent: Option<DefIndex>,
140 /// The identifier of this node.
141 pub disambiguated_data: DisambiguatedDefPathData,
145 pub(crate) fn compute_stable_hash(&self, parent: DefPathHash) -> DefPathHash {
146 let mut hasher = StableHasher::new();
148 parent.hash(&mut hasher);
150 let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
152 std::mem::discriminant(data).hash(&mut hasher);
153 if let Some(name) = data.get_opt_name() {
154 // Get a stable hash by considering the symbol chars rather than
156 name.as_str().hash(&mut hasher);
159 disambiguator.hash(&mut hasher);
161 let local_hash: u64 = hasher.finish();
163 // Construct the new DefPathHash, making sure that the `crate_id`
164 // portion of the hash is properly copied from the parent. This way the
165 // `crate_id` part will be recursively propagated from the root to all
166 // DefPathHashes in this DefPathTable.
167 DefPathHash::new(parent.stable_crate_id(), local_hash)
171 /// A pair of `DefPathData` and an integer disambiguator. The integer is
172 /// normally `0`, but in the event that there are multiple defs with the
173 /// same `parent` and `data`, we use this field to disambiguate
174 /// between them. This introduces some artificial ordering dependency
175 /// but means that if you have, e.g., two impls for the same type in
176 /// the same module, they do get distinct `DefId`s.
177 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
178 pub struct DisambiguatedDefPathData {
179 pub data: DefPathData,
180 pub disambiguator: u32,
183 impl DisambiguatedDefPathData {
184 pub fn fmt_maybe_verbose(&self, writer: &mut impl Write, verbose: bool) -> fmt::Result {
185 match self.data.name() {
186 DefPathDataName::Named(name) => {
187 if verbose && self.disambiguator != 0 {
188 write!(writer, "{}#{}", name, self.disambiguator)
190 writer.write_str(&name.as_str())
193 DefPathDataName::Anon { namespace } => {
194 write!(writer, "{{{}#{}}}", namespace, self.disambiguator)
200 impl fmt::Display for DisambiguatedDefPathData {
201 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
202 self.fmt_maybe_verbose(f, true)
206 #[derive(Clone, Debug, Encodable, Decodable)]
208 /// The path leading from the crate root to the item.
209 pub data: Vec<DisambiguatedDefPathData>,
211 /// The crate root this path is relative to.
216 pub fn make<FN>(krate: CrateNum, start_index: DefIndex, mut get_key: FN) -> DefPath
218 FN: FnMut(DefIndex) -> DefKey,
220 let mut data = vec![];
221 let mut index = Some(start_index);
223 debug!("DefPath::make: krate={:?} index={:?}", krate, index);
224 let p = index.unwrap();
225 let key = get_key(p);
226 debug!("DefPath::make: key={:?}", key);
227 match key.disambiguated_data.data {
228 DefPathData::CrateRoot => {
229 assert!(key.parent.is_none());
233 data.push(key.disambiguated_data);
239 DefPath { data, krate }
242 /// Returns a string representation of the `DefPath` without
243 /// the crate-prefix. This method is useful if you don't have
244 /// a `TyCtxt` available.
245 pub fn to_string_no_crate_verbose(&self) -> String {
246 let mut s = String::with_capacity(self.data.len() * 16);
248 for component in &self.data {
249 write!(s, "::{}", component).unwrap();
255 /// Returns a filename-friendly string of the `DefPath`, without
256 /// the crate-prefix. This method is useful if you don't have
257 /// a `TyCtxt` available.
258 pub fn to_filename_friendly_no_crate(&self) -> String {
259 let mut s = String::with_capacity(self.data.len() * 16);
261 let mut opt_delimiter = None;
262 for component in &self.data {
263 s.extend(opt_delimiter);
264 opt_delimiter = Some('-');
265 write!(s, "{}", component).unwrap();
272 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
273 pub enum DefPathData {
274 // Root: these should only be used for the root nodes, because
275 // they are treated specially by the `def_path` function.
276 /// The crate root (marker).
278 // Catch-all for random `DefId` things like `DUMMY_NODE_ID`.
281 // Different kinds of items and item-like things:
284 /// Something in the type namespace.
286 /// Something in the value namespace.
288 /// Something in the macro namespace.
290 /// Something in the lifetime namespace.
292 /// A closure expression.
295 // Subportions of items:
296 /// Implicit constructor for a unit or tuple-like struct or enum variant.
298 /// A constant expression (see `{ast,hir}::AnonConst`).
300 /// An `impl Trait` type node.
305 pub fn def_path_table(&self) -> &DefPathTable {
309 /// Gets the number of definitions.
310 pub fn def_index_count(&self) -> usize {
311 self.table.index_to_key.len()
314 pub fn def_key(&self, id: LocalDefId) -> DefKey {
315 self.table.def_key(id.local_def_index)
319 pub fn def_path_hash(&self, id: LocalDefId) -> DefPathHash {
320 self.table.def_path_hash(id.local_def_index)
323 /// Returns the path from the crate root to `index`. The root
324 /// nodes are not included in the path (i.e., this will be an
325 /// empty vector for the crate root). For an inlined item, this
326 /// will be the path of the item in the external crate (but the
327 /// path will begin with the path to the external crate).
328 pub fn def_path(&self, id: LocalDefId) -> DefPath {
329 DefPath::make(LOCAL_CRATE, id.local_def_index, |index| {
330 self.def_key(LocalDefId { local_def_index: index })
336 pub fn local_def_id_to_hir_id(&self, id: LocalDefId) -> hir::HirId {
337 self.def_id_to_hir_id[id].unwrap()
341 pub fn opt_hir_id_to_local_def_id(&self, hir_id: hir::HirId) -> Option<LocalDefId> {
342 self.hir_id_to_def_id.get(&hir_id).copied()
345 /// Adds a root definition (no parent) and a few other reserved definitions.
346 pub fn new(crate_name: &str, crate_disambiguator: CrateDisambiguator) -> Definitions {
349 disambiguated_data: DisambiguatedDefPathData {
350 data: DefPathData::CrateRoot,
355 let stable_crate_id = StableCrateId::new(crate_name, crate_disambiguator);
356 let parent_hash = DefPathHash::new(stable_crate_id, 0);
357 let def_path_hash = key.compute_stable_hash(parent_hash);
359 // Create the root definition.
360 let mut table = DefPathTable::default();
361 let root = LocalDefId { local_def_index: table.allocate(key, def_path_hash) };
362 assert_eq!(root.local_def_index, CRATE_DEF_INDEX);
366 def_id_to_hir_id: Default::default(),
367 hir_id_to_def_id: Default::default(),
368 expansions_that_defined: Default::default(),
369 parent_modules_of_macro_defs: Default::default(),
373 /// Retrieves the root definition.
374 pub fn get_root_def(&self) -> LocalDefId {
375 LocalDefId { local_def_index: CRATE_DEF_INDEX }
378 /// Adds a definition with a parent definition.
384 mut next_disambiguator: impl FnMut(LocalDefId, DefPathData) -> u32,
386 debug!("create_def(parent={:?}, data={:?}, expn_id={:?})", parent, data, expn_id);
388 // The root node must be created with `create_root_def()`.
389 assert!(data != DefPathData::CrateRoot);
391 let disambiguator = next_disambiguator(parent, data);
393 parent: Some(parent.local_def_index),
394 disambiguated_data: DisambiguatedDefPathData { data, disambiguator },
397 let parent_hash = self.table.def_path_hash(parent.local_def_index);
398 let def_path_hash = key.compute_stable_hash(parent_hash);
400 debug!("create_def: after disambiguation, key = {:?}", key);
402 // Create the definition.
403 let def_id = LocalDefId { local_def_index: self.table.allocate(key, def_path_hash) };
405 if expn_id != ExpnId::root() {
406 self.expansions_that_defined.insert(def_id, expn_id);
412 /// Initializes the `LocalDefId` to `HirId` mapping once it has been generated during
413 /// AST to HIR lowering.
414 pub fn init_def_id_to_hir_id_mapping(
416 mapping: IndexVec<LocalDefId, Option<hir::HirId>>,
419 self.def_id_to_hir_id.is_empty(),
420 "trying to initialize `LocalDefId` <-> `HirId` mappings twice"
423 // Build the reverse mapping of `def_id_to_hir_id`.
424 self.hir_id_to_def_id = mapping
426 .filter_map(|(def_id, hir_id)| hir_id.map(|hir_id| (hir_id, def_id)))
429 self.def_id_to_hir_id = mapping;
432 pub fn expansion_that_defined(&self, id: LocalDefId) -> ExpnId {
433 self.expansions_that_defined.get(&id).copied().unwrap_or_else(ExpnId::root)
436 pub fn parent_module_of_macro_def(&self, expn_id: ExpnId) -> DefId {
437 self.parent_modules_of_macro_defs[&expn_id]
440 pub fn add_parent_module_of_macro_def(&mut self, expn_id: ExpnId, module: DefId) {
441 self.parent_modules_of_macro_defs.insert(expn_id, module);
444 pub fn iter_local_def_id(&self) -> impl Iterator<Item = LocalDefId> + '_ {
445 self.def_id_to_hir_id.iter_enumerated().map(|(k, _)| k)
449 #[derive(Copy, Clone, PartialEq, Debug)]
450 pub enum DefPathDataName {
452 Anon { namespace: Symbol },
456 pub fn get_opt_name(&self) -> Option<Symbol> {
457 use self::DefPathData::*;
459 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
461 Impl | CrateRoot | Misc | ClosureExpr | Ctor | AnonConst | ImplTrait => None,
465 pub fn name(&self) -> DefPathDataName {
466 use self::DefPathData::*;
468 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => {
469 DefPathDataName::Named(name)
471 // Note that this does not show up in user print-outs.
472 CrateRoot => DefPathDataName::Anon { namespace: kw::Crate },
473 Impl => DefPathDataName::Anon { namespace: kw::Impl },
474 Misc => DefPathDataName::Anon { namespace: sym::misc },
475 ClosureExpr => DefPathDataName::Anon { namespace: sym::closure },
476 Ctor => DefPathDataName::Anon { namespace: sym::constructor },
477 AnonConst => DefPathDataName::Anon { namespace: sym::constant },
478 ImplTrait => DefPathDataName::Anon { namespace: sym::opaque },
483 impl fmt::Display for DefPathData {
484 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
486 DefPathDataName::Named(name) => f.write_str(&name.as_str()),
487 // FIXME(#70334): this will generate legacy {{closure}}, {{impl}}, etc
488 DefPathDataName::Anon { namespace } => write!(f, "{{{{{}}}}}", namespace),