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::hygiene::ExpnId;
18 use rustc_span::symbol::{kw, sym, Symbol};
20 use std::fmt::{self, Write};
24 /// The `DefPathTable` maps `DefIndex`es to `DefKey`s and vice versa.
25 /// Internally the `DefPathTable` holds a tree of `DefKey`s, where each `DefKey`
26 /// stores the `DefIndex` of its parent.
27 /// There is one `DefPathTable` for each crate.
28 #[derive(Clone, Default)]
29 pub struct DefPathTable {
30 index_to_key: IndexVec<DefIndex, DefKey>,
31 def_path_hashes: IndexVec<DefIndex, DefPathHash>,
32 def_path_hash_to_index: UnhashMap<DefPathHash, DefIndex>,
36 fn allocate(&mut self, key: DefKey, def_path_hash: DefPathHash) -> DefIndex {
38 let index = DefIndex::from(self.index_to_key.len());
39 debug!("DefPathTable::insert() - {:?} <-> {:?}", key, index);
40 self.index_to_key.push(key);
43 self.def_path_hashes.push(def_path_hash);
44 debug_assert!(self.def_path_hashes.len() == self.index_to_key.len());
46 // Check for hash collisions of DefPathHashes. These should be
48 if let Some(existing) = self.def_path_hash_to_index.insert(def_path_hash, index) {
49 let def_path1 = DefPath::make(LOCAL_CRATE, existing, |idx| self.def_key(idx));
50 let def_path2 = DefPath::make(LOCAL_CRATE, index, |idx| self.def_key(idx));
52 // Continuing with colliding DefPathHashes can lead to correctness
53 // issues. We must abort compilation.
55 // The likelyhood of such a collision is very small, so actually
56 // running into one could be indicative of a poor hash function
59 // See the documentation for DefPathHash for more information.
61 "found DefPathHash collsion between {:?} and {:?}. \
62 Compilation cannot continue.",
67 // Assert that all DefPathHashes correctly contain the local crate's
69 #[cfg(debug_assertions)]
70 if let Some(root) = self.def_path_hashes.get(CRATE_DEF_INDEX) {
71 assert!(def_path_hash.stable_crate_id() == root.stable_crate_id());
78 pub fn def_key(&self, index: DefIndex) -> DefKey {
79 self.index_to_key[index]
83 pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
84 let hash = self.def_path_hashes[index];
85 debug!("def_path_hash({:?}) = {:?}", index, hash);
89 pub fn enumerated_keys_and_path_hashes(
91 ) -> impl Iterator<Item = (DefIndex, &DefKey, &DefPathHash)> + '_ {
94 .map(move |(index, key)| (index, key, &self.def_path_hashes[index]))
97 pub fn all_def_path_hashes_and_def_ids(
100 ) -> impl Iterator<Item = (DefPathHash, DefId)> + '_ {
103 .map(move |(index, hash)| (*hash, DefId { krate, index }))
107 /// The definition table containing node definitions.
108 /// It holds the `DefPathTable` for `LocalDefId`s/`DefPath`s.
109 /// It also stores mappings to convert `LocalDefId`s to/from `HirId`s.
111 pub struct Definitions {
114 // FIXME(eddyb) ideally all `LocalDefId`s would be HIR owners.
115 pub(super) def_id_to_hir_id: IndexVec<LocalDefId, Option<hir::HirId>>,
116 /// The reverse mapping of `def_id_to_hir_id`.
117 pub(super) hir_id_to_def_id: FxHashMap<hir::HirId, LocalDefId>,
119 /// If `ExpnId` is an ID of some macro expansion,
120 /// then `DefId` is the normal module (`mod`) in which the expanded macro was defined.
121 parent_modules_of_macro_defs: FxHashMap<ExpnId, DefId>,
122 /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
123 expansions_that_defined: FxHashMap<LocalDefId, ExpnId>,
126 /// A unique identifier that we can use to lookup a definition
127 /// precisely. It combines the index of the definition's parent (if
128 /// any) with a `DisambiguatedDefPathData`.
129 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
132 pub parent: Option<DefIndex>,
134 /// The identifier of this node.
135 pub disambiguated_data: DisambiguatedDefPathData,
139 pub(crate) fn compute_stable_hash(&self, parent: DefPathHash) -> DefPathHash {
140 let mut hasher = StableHasher::new();
142 parent.hash(&mut hasher);
144 let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
146 std::mem::discriminant(data).hash(&mut hasher);
147 if let Some(name) = data.get_opt_name() {
148 // Get a stable hash by considering the symbol chars rather than
150 name.as_str().hash(&mut hasher);
153 disambiguator.hash(&mut hasher);
155 let local_hash: u64 = hasher.finish();
157 // Construct the new DefPathHash, making sure that the `crate_id`
158 // portion of the hash is properly copied from the parent. This way the
159 // `crate_id` part will be recursively propagated from the root to all
160 // DefPathHashes in this DefPathTable.
161 DefPathHash::new(parent.stable_crate_id(), local_hash)
165 /// A pair of `DefPathData` and an integer disambiguator. The integer is
166 /// normally `0`, but in the event that there are multiple defs with the
167 /// same `parent` and `data`, we use this field to disambiguate
168 /// between them. This introduces some artificial ordering dependency
169 /// but means that if you have, e.g., two impls for the same type in
170 /// the same module, they do get distinct `DefId`s.
171 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
172 pub struct DisambiguatedDefPathData {
173 pub data: DefPathData,
174 pub disambiguator: u32,
177 impl DisambiguatedDefPathData {
178 pub fn fmt_maybe_verbose(&self, writer: &mut impl Write, verbose: bool) -> fmt::Result {
179 match self.data.name() {
180 DefPathDataName::Named(name) => {
181 if verbose && self.disambiguator != 0 {
182 write!(writer, "{}#{}", name, self.disambiguator)
184 writer.write_str(&name.as_str())
187 DefPathDataName::Anon { namespace } => {
188 write!(writer, "{{{}#{}}}", namespace, self.disambiguator)
194 impl fmt::Display for DisambiguatedDefPathData {
195 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
196 self.fmt_maybe_verbose(f, true)
200 #[derive(Clone, Debug, Encodable, Decodable)]
202 /// The path leading from the crate root to the item.
203 pub data: Vec<DisambiguatedDefPathData>,
205 /// The crate root this path is relative to.
210 pub fn make<FN>(krate: CrateNum, start_index: DefIndex, mut get_key: FN) -> DefPath
212 FN: FnMut(DefIndex) -> DefKey,
214 let mut data = vec![];
215 let mut index = Some(start_index);
217 debug!("DefPath::make: krate={:?} index={:?}", krate, index);
218 let p = index.unwrap();
219 let key = get_key(p);
220 debug!("DefPath::make: key={:?}", key);
221 match key.disambiguated_data.data {
222 DefPathData::CrateRoot => {
223 assert!(key.parent.is_none());
227 data.push(key.disambiguated_data);
233 DefPath { data, krate }
236 /// Returns a string representation 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_string_no_crate_verbose(&self) -> String {
240 let mut s = String::with_capacity(self.data.len() * 16);
242 for component in &self.data {
243 write!(s, "::{}", component).unwrap();
249 /// Returns a filename-friendly string of the `DefPath`, without
250 /// the crate-prefix. This method is useful if you don't have
251 /// a `TyCtxt` available.
252 pub fn to_filename_friendly_no_crate(&self) -> String {
253 let mut s = String::with_capacity(self.data.len() * 16);
255 let mut opt_delimiter = None;
256 for component in &self.data {
257 s.extend(opt_delimiter);
258 opt_delimiter = Some('-');
259 write!(s, "{}", component).unwrap();
266 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
267 pub enum DefPathData {
268 // Root: these should only be used for the root nodes, because
269 // they are treated specially by the `def_path` function.
270 /// The crate root (marker).
272 // Catch-all for random `DefId` things like `DUMMY_NODE_ID`.
275 // Different kinds of items and item-like things:
278 /// Something in the type namespace.
280 /// Something in the value namespace.
282 /// Something in the macro namespace.
284 /// Something in the lifetime namespace.
286 /// A closure expression.
289 // Subportions of items:
290 /// Implicit constructor for a unit or tuple-like struct or enum variant.
292 /// A constant expression (see `{ast,hir}::AnonConst`).
294 /// An `impl Trait` type node.
299 pub fn def_path_table(&self) -> &DefPathTable {
303 /// Gets the number of definitions.
304 pub fn def_index_count(&self) -> usize {
305 self.table.index_to_key.len()
309 pub fn def_key(&self, id: LocalDefId) -> DefKey {
310 self.table.def_key(id.local_def_index)
314 pub fn def_path_hash(&self, id: LocalDefId) -> DefPathHash {
315 self.table.def_path_hash(id.local_def_index)
318 /// Returns the path from the crate root to `index`. The root
319 /// nodes are not included in the path (i.e., this will be an
320 /// empty vector for the crate root). For an inlined item, this
321 /// will be the path of the item in the external crate (but the
322 /// path will begin with the path to the external crate).
323 pub fn def_path(&self, id: LocalDefId) -> DefPath {
324 DefPath::make(LOCAL_CRATE, id.local_def_index, |index| {
325 self.def_key(LocalDefId { local_def_index: index })
331 pub fn local_def_id_to_hir_id(&self, id: LocalDefId) -> hir::HirId {
332 self.def_id_to_hir_id[id].unwrap()
336 pub fn opt_hir_id_to_local_def_id(&self, hir_id: hir::HirId) -> Option<LocalDefId> {
337 self.hir_id_to_def_id.get(&hir_id).copied()
340 /// Adds a root definition (no parent) and a few other reserved definitions.
341 pub fn new(stable_crate_id: StableCrateId) -> Definitions {
344 disambiguated_data: DisambiguatedDefPathData {
345 data: DefPathData::CrateRoot,
350 let parent_hash = DefPathHash::new(stable_crate_id, 0);
351 let def_path_hash = key.compute_stable_hash(parent_hash);
353 // Create the root definition.
354 let mut table = DefPathTable::default();
355 let root = LocalDefId { local_def_index: table.allocate(key, def_path_hash) };
356 assert_eq!(root.local_def_index, CRATE_DEF_INDEX);
360 def_id_to_hir_id: Default::default(),
361 hir_id_to_def_id: Default::default(),
362 expansions_that_defined: Default::default(),
363 parent_modules_of_macro_defs: Default::default(),
367 /// Retrieves the root definition.
368 pub fn get_root_def(&self) -> LocalDefId {
369 LocalDefId { local_def_index: CRATE_DEF_INDEX }
372 /// Adds a definition with a parent definition.
378 mut next_disambiguator: impl FnMut(LocalDefId, DefPathData) -> u32,
380 debug!("create_def(parent={:?}, data={:?}, expn_id={:?})", parent, data, expn_id);
382 // The root node must be created with `create_root_def()`.
383 assert!(data != DefPathData::CrateRoot);
385 let disambiguator = next_disambiguator(parent, data);
387 parent: Some(parent.local_def_index),
388 disambiguated_data: DisambiguatedDefPathData { data, disambiguator },
391 let parent_hash = self.table.def_path_hash(parent.local_def_index);
392 let def_path_hash = key.compute_stable_hash(parent_hash);
394 debug!("create_def: after disambiguation, key = {:?}", key);
396 // Create the definition.
397 let def_id = LocalDefId { local_def_index: self.table.allocate(key, def_path_hash) };
399 if expn_id != ExpnId::root() {
400 self.expansions_that_defined.insert(def_id, expn_id);
406 /// Initializes the `LocalDefId` to `HirId` mapping once it has been generated during
407 /// AST to HIR lowering.
408 pub fn init_def_id_to_hir_id_mapping(
410 mapping: IndexVec<LocalDefId, Option<hir::HirId>>,
413 self.def_id_to_hir_id.is_empty(),
414 "trying to initialize `LocalDefId` <-> `HirId` mappings twice"
417 // Build the reverse mapping of `def_id_to_hir_id`.
418 self.hir_id_to_def_id = mapping
420 .filter_map(|(def_id, hir_id)| hir_id.map(|hir_id| (hir_id, def_id)))
423 self.def_id_to_hir_id = mapping;
426 pub fn expansion_that_defined(&self, id: LocalDefId) -> ExpnId {
427 self.expansions_that_defined.get(&id).copied().unwrap_or_else(ExpnId::root)
430 pub fn parent_module_of_macro_def(&self, expn_id: ExpnId) -> DefId {
431 self.parent_modules_of_macro_defs[&expn_id]
434 pub fn add_parent_module_of_macro_def(&mut self, expn_id: ExpnId, module: DefId) {
435 self.parent_modules_of_macro_defs.insert(expn_id, module);
438 pub fn iter_local_def_id(&self) -> impl Iterator<Item = LocalDefId> + '_ {
439 self.def_id_to_hir_id.iter_enumerated().map(|(k, _)| k)
443 #[derive(Copy, Clone, PartialEq, Debug)]
444 pub enum DefPathDataName {
446 Anon { namespace: Symbol },
450 pub fn get_opt_name(&self) -> Option<Symbol> {
451 use self::DefPathData::*;
453 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
455 Impl | CrateRoot | Misc | ClosureExpr | Ctor | AnonConst | ImplTrait => None,
459 pub fn name(&self) -> DefPathDataName {
460 use self::DefPathData::*;
462 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => {
463 DefPathDataName::Named(name)
465 // Note that this does not show up in user print-outs.
466 CrateRoot => DefPathDataName::Anon { namespace: kw::Crate },
467 Impl => DefPathDataName::Anon { namespace: kw::Impl },
468 Misc => DefPathDataName::Anon { namespace: sym::misc },
469 ClosureExpr => DefPathDataName::Anon { namespace: sym::closure },
470 Ctor => DefPathDataName::Anon { namespace: sym::constructor },
471 AnonConst => DefPathDataName::Anon { namespace: sym::constant },
472 ImplTrait => DefPathDataName::Anon { namespace: sym::opaque },
477 impl fmt::Display for DefPathData {
478 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
480 DefPathDataName::Named(name) => f.write_str(&name.as_str()),
481 // FIXME(#70334): this will generate legacy {{closure}}, {{impl}}, etc
482 DefPathDataName::Anon { namespace } => write!(f, "{{{{{}}}}}", namespace),