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::symbol::{kw, sym, Symbol};
16 use std::fmt::{self, Write};
19 /// The `DefPathTable` maps `DefIndex`es to `DefKey`s and vice versa.
20 /// Internally the `DefPathTable` holds a tree of `DefKey`s, where each `DefKey`
21 /// stores the `DefIndex` of its parent.
22 /// There is one `DefPathTable` for each crate.
23 #[derive(Clone, Default, Debug)]
24 pub struct DefPathTable {
25 index_to_key: IndexVec<DefIndex, DefKey>,
26 def_path_hashes: IndexVec<DefIndex, DefPathHash>,
27 def_path_hash_to_index: DefPathHashMap,
31 fn allocate(&mut self, key: DefKey, def_path_hash: DefPathHash) -> DefIndex {
33 let index = DefIndex::from(self.index_to_key.len());
34 debug!("DefPathTable::insert() - {:?} <-> {:?}", key, index);
35 self.index_to_key.push(key);
38 self.def_path_hashes.push(def_path_hash);
39 debug_assert!(self.def_path_hashes.len() == self.index_to_key.len());
41 // Check for hash collisions of DefPathHashes. These should be
43 if let Some(existing) = self.def_path_hash_to_index.insert(&def_path_hash, &index) {
44 let def_path1 = DefPath::make(LOCAL_CRATE, existing, |idx| self.def_key(idx));
45 let def_path2 = DefPath::make(LOCAL_CRATE, index, |idx| self.def_key(idx));
47 // Continuing with colliding DefPathHashes can lead to correctness
48 // issues. We must abort compilation.
50 // The likelihood of such a collision is very small, so actually
51 // running into one could be indicative of a poor hash function
54 // See the documentation for DefPathHash for more information.
56 "found DefPathHash collision between {def_path1:?} and {def_path2:?}. \
57 Compilation cannot continue."
61 // Assert that all DefPathHashes correctly contain the local crate's
63 #[cfg(debug_assertions)]
64 if let Some(root) = self.def_path_hashes.get(CRATE_DEF_INDEX) {
65 assert!(def_path_hash.stable_crate_id() == root.stable_crate_id());
72 pub fn def_key(&self, index: DefIndex) -> DefKey {
73 self.index_to_key[index]
77 pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
78 let hash = self.def_path_hashes[index];
79 debug!("def_path_hash({:?}) = {:?}", index, hash);
83 pub fn enumerated_keys_and_path_hashes(
85 ) -> impl Iterator<Item = (DefIndex, &DefKey, &DefPathHash)> + ExactSizeIterator + '_ {
88 .map(move |(index, key)| (index, key, &self.def_path_hashes[index]))
92 /// The definition table containing node definitions.
93 /// It holds the `DefPathTable` for `LocalDefId`s/`DefPath`s.
94 /// It also stores mappings to convert `LocalDefId`s to/from `HirId`s.
95 #[derive(Clone, Debug)]
96 pub struct Definitions {
98 next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>,
100 /// The [StableCrateId] of the local crate.
101 stable_crate_id: StableCrateId,
104 /// A unique identifier that we can use to lookup a definition
105 /// precisely. It combines the index of the definition's parent (if
106 /// any) with a `DisambiguatedDefPathData`.
107 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
110 pub parent: Option<DefIndex>,
112 /// The identifier of this node.
113 pub disambiguated_data: DisambiguatedDefPathData,
117 pub(crate) fn compute_stable_hash(&self, parent: DefPathHash) -> DefPathHash {
118 let mut hasher = StableHasher::new();
120 parent.hash(&mut hasher);
122 let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
124 std::mem::discriminant(data).hash(&mut hasher);
125 if let Some(name) = data.get_opt_name() {
126 // Get a stable hash by considering the symbol chars rather than
128 name.as_str().hash(&mut hasher);
131 disambiguator.hash(&mut hasher);
133 let local_hash: u64 = hasher.finish();
135 // Construct the new DefPathHash, making sure that the `crate_id`
136 // portion of the hash is properly copied from the parent. This way the
137 // `crate_id` part will be recursively propagated from the root to all
138 // DefPathHashes in this DefPathTable.
139 DefPathHash::new(parent.stable_crate_id(), local_hash)
143 pub fn get_opt_name(&self) -> Option<Symbol> {
144 self.disambiguated_data.data.get_opt_name()
148 /// A pair of `DefPathData` and an integer disambiguator. The integer is
149 /// normally `0`, but in the event that there are multiple defs with the
150 /// same `parent` and `data`, we use this field to disambiguate
151 /// between them. This introduces some artificial ordering dependency
152 /// but means that if you have, e.g., two impls for the same type in
153 /// the same module, they do get distinct `DefId`s.
154 #[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
155 pub struct DisambiguatedDefPathData {
156 pub data: DefPathData,
157 pub disambiguator: u32,
160 impl DisambiguatedDefPathData {
161 pub fn fmt_maybe_verbose(&self, writer: &mut impl Write, verbose: bool) -> fmt::Result {
162 match self.data.name() {
163 DefPathDataName::Named(name) => {
164 if verbose && self.disambiguator != 0 {
165 write!(writer, "{}#{}", name, self.disambiguator)
167 writer.write_str(name.as_str())
170 DefPathDataName::Anon { namespace } => {
171 write!(writer, "{{{}#{}}}", namespace, self.disambiguator)
177 impl fmt::Display for DisambiguatedDefPathData {
178 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
179 self.fmt_maybe_verbose(f, true)
183 #[derive(Clone, Debug, Encodable, Decodable)]
185 /// The path leading from the crate root to the item.
186 pub data: Vec<DisambiguatedDefPathData>,
188 /// The crate root this path is relative to.
193 pub fn make<FN>(krate: CrateNum, start_index: DefIndex, mut get_key: FN) -> DefPath
195 FN: FnMut(DefIndex) -> DefKey,
197 let mut data = vec![];
198 let mut index = Some(start_index);
200 debug!("DefPath::make: krate={:?} index={:?}", krate, index);
201 let p = index.unwrap();
202 let key = get_key(p);
203 debug!("DefPath::make: key={:?}", key);
204 match key.disambiguated_data.data {
205 DefPathData::CrateRoot => {
206 assert!(key.parent.is_none());
210 data.push(key.disambiguated_data);
216 DefPath { data, krate }
219 /// Returns a string representation of the `DefPath` without
220 /// the crate-prefix. This method is useful if you don't have
221 /// a `TyCtxt` available.
222 pub fn to_string_no_crate_verbose(&self) -> String {
223 let mut s = String::with_capacity(self.data.len() * 16);
225 for component in &self.data {
226 write!(s, "::{component}").unwrap();
232 /// Returns a filename-friendly string of the `DefPath`, without
233 /// the crate-prefix. This method is useful if you don't have
234 /// a `TyCtxt` available.
235 pub fn to_filename_friendly_no_crate(&self) -> String {
236 let mut s = String::with_capacity(self.data.len() * 16);
238 let mut opt_delimiter = None;
239 for component in &self.data {
240 s.extend(opt_delimiter);
241 opt_delimiter = Some('-');
242 write!(s, "{component}").unwrap();
249 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
250 pub enum DefPathData {
251 // Root: these should only be used for the root nodes, because
252 // they are treated specially by the `def_path` function.
253 /// The crate root (marker).
256 // Different kinds of items and item-like things:
259 /// An `extern` block.
263 /// A global asm item.
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 })
316 /// Adds a root definition (no parent) and a few other reserved definitions.
317 pub fn new(stable_crate_id: StableCrateId) -> Definitions {
320 disambiguated_data: DisambiguatedDefPathData {
321 data: DefPathData::CrateRoot,
326 let parent_hash = DefPathHash::new(stable_crate_id, 0);
327 let def_path_hash = key.compute_stable_hash(parent_hash);
329 // Create the root definition.
330 let mut table = DefPathTable::default();
331 let root = LocalDefId { local_def_index: table.allocate(key, def_path_hash) };
332 assert_eq!(root.local_def_index, CRATE_DEF_INDEX);
334 Definitions { table, next_disambiguator: Default::default(), stable_crate_id }
337 /// Adds a definition with a parent definition.
338 pub fn create_def(&mut self, parent: LocalDefId, data: DefPathData) -> LocalDefId {
339 // We can't use `Debug` implementation for `LocalDefId` here, since it tries to acquire a
340 // reference to `Definitions` and we're already holding a mutable reference.
342 "create_def(parent={}, data={data:?})",
343 self.def_path(parent).to_string_no_crate_verbose(),
346 // The root node must be created with `create_root_def()`.
347 assert!(data != DefPathData::CrateRoot);
349 // Find the next free disambiguator for this key.
350 let disambiguator = {
351 let next_disamb = self.next_disambiguator.entry((parent, data)).or_insert(0);
352 let disambiguator = *next_disamb;
353 *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
357 parent: Some(parent.local_def_index),
358 disambiguated_data: DisambiguatedDefPathData { data, disambiguator },
361 let parent_hash = self.table.def_path_hash(parent.local_def_index);
362 let def_path_hash = key.compute_stable_hash(parent_hash);
364 debug!("create_def: after disambiguation, key = {:?}", key);
366 // Create the definition.
367 LocalDefId { local_def_index: self.table.allocate(key, def_path_hash) }
371 pub fn local_def_path_hash_to_def_id(
374 err: &mut dyn FnMut() -> !,
376 debug_assert!(hash.stable_crate_id() == self.stable_crate_id);
378 .def_path_hash_to_index
380 .map(|local_def_index| LocalDefId { local_def_index })
381 .unwrap_or_else(|| err())
384 pub fn def_path_hash_to_def_index_map(&self) -> &DefPathHashMap {
385 &self.table.def_path_hash_to_index
388 pub fn num_definitions(&self) -> usize {
389 self.table.def_path_hashes.len()
393 #[derive(Copy, Clone, PartialEq, Debug)]
394 pub enum DefPathDataName {
396 Anon { namespace: Symbol },
400 pub fn get_opt_name(&self) -> Option<Symbol> {
401 use self::DefPathData::*;
403 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
405 Impl | ForeignMod | CrateRoot | Use | GlobalAsm | ClosureExpr | Ctor | AnonConst
410 pub fn name(&self) -> DefPathDataName {
411 use self::DefPathData::*;
413 TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => {
414 DefPathDataName::Named(name)
416 // Note that this does not show up in user print-outs.
417 CrateRoot => DefPathDataName::Anon { namespace: kw::Crate },
418 Impl => DefPathDataName::Anon { namespace: kw::Impl },
419 ForeignMod => DefPathDataName::Anon { namespace: kw::Extern },
420 Use => DefPathDataName::Anon { namespace: kw::Use },
421 GlobalAsm => DefPathDataName::Anon { namespace: sym::global_asm },
422 ClosureExpr => DefPathDataName::Anon { namespace: sym::closure },
423 Ctor => DefPathDataName::Anon { namespace: sym::constructor },
424 AnonConst => DefPathDataName::Anon { namespace: sym::constant },
425 ImplTrait => DefPathDataName::Anon { namespace: sym::opaque },
430 impl fmt::Display for DefPathData {
431 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
433 DefPathDataName::Named(name) => f.write_str(name.as_str()),
434 // FIXME(#70334): this will generate legacy {{closure}}, {{impl}}, etc
435 DefPathDataName::Anon { namespace } => write!(f, "{{{{{namespace}}}}}"),