1 //! Machinery for hygienic macros.
3 //! Inspired by Matthew Flatt et al., “Macros That Work Together: Compile-Time Bindings, Partial
4 //! Expansion, and Definition Contexts,” *Journal of Functional Programming* 22, no. 2
5 //! (March 1, 2012): 181–216, <https://doi.org/10.1017/S0956796812000093>.
7 // Hygiene data is stored in a global variable and accessed via TLS, which
8 // means that accesses are somewhat expensive. (`HygieneData::with`
9 // encapsulates a single access.) Therefore, on hot code paths it is worth
10 // ensuring that multiple HygieneData accesses are combined into a single
11 // `HygieneData::with`.
13 // This explains why `HygieneData`, `SyntaxContext` and `ExpnId` have interfaces
14 // with a certain amount of redundancy in them. For example,
15 // `SyntaxContext::outer_expn_data` combines `SyntaxContext::outer` and
16 // `ExpnId::expn_data` so that two `HygieneData` accesses can be performed within
17 // a single `HygieneData::with` call.
19 // It also explains why many functions appear in `HygieneData` and again in
20 // `SyntaxContext` or `ExpnId`. For example, `HygieneData::outer` and
21 // `SyntaxContext::outer` do the same thing, but the former is for use within a
22 // `HygieneData::with` call while the latter is for use outside such a call.
23 // When modifying this file it is important to understand this distinction,
24 // because getting it wrong can lead to nested `HygieneData::with` calls that
25 // trigger runtime aborts. (Fortunately these are obvious and easy to fix.)
27 use crate::edition::Edition;
28 use crate::symbol::{kw, sym, Symbol};
29 use crate::with_session_globals;
30 use crate::{HashStableContext, Span, DUMMY_SP};
32 use crate::def_id::{CrateNum, DefId, StableCrateId, CRATE_DEF_ID, LOCAL_CRATE};
33 use rustc_data_structures::fingerprint::Fingerprint;
34 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
35 use rustc_data_structures::stable_hasher::HashingControls;
36 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
37 use rustc_data_structures::sync::{Lock, Lrc};
38 use rustc_data_structures::unhash::UnhashMap;
39 use rustc_index::vec::IndexVec;
40 use rustc_macros::HashStable_Generic;
41 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
45 /// A `SyntaxContext` represents a chain of pairs `(ExpnId, Transparency)` named "marks".
46 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
47 pub struct SyntaxContext(u32);
49 #[derive(Debug, Encodable, Decodable, Clone)]
50 pub struct SyntaxContextData {
52 outer_transparency: Transparency,
53 parent: SyntaxContext,
54 /// This context, but with all transparent and semi-transparent expansions filtered away.
55 opaque: SyntaxContext,
56 /// This context, but with all transparent expansions filtered away.
57 opaque_and_semitransparent: SyntaxContext,
58 /// Name of the crate to which `$crate` with this context would resolve.
59 dollar_crate_name: Symbol,
62 rustc_index::newtype_index! {
63 /// A unique ID associated with a macro invocation and expansion.
65 pub struct ExpnIndex {}
68 /// A unique ID associated with a macro invocation and expansion.
69 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
72 pub local_id: ExpnIndex,
75 impl fmt::Debug for ExpnId {
76 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
77 // Generate crate_::{{expn_}}.
78 write!(f, "{:?}::{{{{expn{}}}}}", self.krate, self.local_id.as_u32())
82 rustc_index::newtype_index! {
83 /// A unique ID associated with a macro invocation and expansion.
86 #[debug_format = "expn{}"]
87 pub struct LocalExpnId {}
90 // To ensure correctness of incremental compilation,
91 // `LocalExpnId` must not implement `Ord` or `PartialOrd`.
92 // See https://github.com/rust-lang/rust/issues/90317.
93 impl !Ord for LocalExpnId {}
94 impl !PartialOrd for LocalExpnId {}
96 /// Assert that the provided `HashStableContext` is configured with the 'default'
97 /// `HashingControls`. We should always have bailed out before getting to here
98 /// with a non-default mode. With this check in place, we can avoid the need
99 /// to maintain separate versions of `ExpnData` hashes for each permutation
100 /// of `HashingControls` settings.
101 fn assert_default_hashing_controls<CTX: HashStableContext>(ctx: &CTX, msg: &str) {
102 match ctx.hashing_controls() {
103 // Note that we require that `hash_spans` be set according to the global
104 // `-Z incremental-ignore-spans` option. Normally, this option is disabled,
105 // which will cause us to require that this method always be called with `Span` hashing
107 HashingControls { hash_spans }
108 if hash_spans == !ctx.unstable_opts_incremental_ignore_spans() => {}
109 other => panic!("Attempted hashing of {msg} with non-default HashingControls: {:?}", other),
113 /// A unique hash value associated to an expansion.
114 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, Encodable, Decodable, HashStable_Generic)]
115 pub struct ExpnHash(Fingerprint);
118 /// Returns the [StableCrateId] identifying the crate this [ExpnHash]
121 pub fn stable_crate_id(self) -> StableCrateId {
122 StableCrateId(self.0.as_value().0)
125 /// Returns the crate-local part of the [ExpnHash].
129 pub fn local_hash(self) -> u64 {
134 pub fn is_root(self) -> bool {
135 self.0 == Fingerprint::ZERO
138 /// Builds a new [ExpnHash] with the given [StableCrateId] and
139 /// `local_hash`, where `local_hash` must be unique within its crate.
140 fn new(stable_crate_id: StableCrateId, local_hash: u64) -> ExpnHash {
141 ExpnHash(Fingerprint::new(stable_crate_id.0, local_hash))
145 /// A property of a macro expansion that determines how identifiers
146 /// produced by that expansion are resolved.
147 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Hash, Debug, Encodable, Decodable)]
148 #[derive(HashStable_Generic)]
149 pub enum Transparency {
150 /// Identifier produced by a transparent expansion is always resolved at call-site.
151 /// Call-site spans in procedural macros, hygiene opt-out in `macro` should use this.
153 /// Identifier produced by a semi-transparent expansion may be resolved
154 /// either at call-site or at definition-site.
155 /// If it's a local variable, label or `$crate` then it's resolved at def-site.
156 /// Otherwise it's resolved at call-site.
157 /// `macro_rules` macros behave like this, built-in macros currently behave like this too,
158 /// but that's an implementation detail.
160 /// Identifier produced by an opaque expansion is always resolved at definition-site.
161 /// Def-site spans in procedural macros, identifiers from `macro` by default use this.
166 /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
167 pub const ROOT: LocalExpnId = LocalExpnId::from_u32(0);
170 pub fn from_raw(idx: ExpnIndex) -> LocalExpnId {
171 LocalExpnId::from_u32(idx.as_u32())
175 pub fn as_raw(self) -> ExpnIndex {
176 ExpnIndex::from_u32(self.as_u32())
179 pub fn fresh_empty() -> LocalExpnId {
180 HygieneData::with(|data| {
181 let expn_id = data.local_expn_data.push(None);
182 let _eid = data.local_expn_hashes.push(ExpnHash(Fingerprint::ZERO));
183 debug_assert_eq!(expn_id, _eid);
188 pub fn fresh(mut expn_data: ExpnData, ctx: impl HashStableContext) -> LocalExpnId {
189 debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
190 let expn_hash = update_disambiguator(&mut expn_data, ctx);
191 HygieneData::with(|data| {
192 let expn_id = data.local_expn_data.push(Some(expn_data));
193 let _eid = data.local_expn_hashes.push(expn_hash);
194 debug_assert_eq!(expn_id, _eid);
195 let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, expn_id.to_expn_id());
196 debug_assert!(_old_id.is_none());
202 pub fn expn_hash(self) -> ExpnHash {
203 HygieneData::with(|data| data.local_expn_hash(self))
207 pub fn expn_data(self) -> ExpnData {
208 HygieneData::with(|data| data.local_expn_data(self).clone())
212 pub fn to_expn_id(self) -> ExpnId {
213 ExpnId { krate: LOCAL_CRATE, local_id: self.as_raw() }
217 pub fn set_expn_data(self, mut expn_data: ExpnData, ctx: impl HashStableContext) {
218 debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
219 let expn_hash = update_disambiguator(&mut expn_data, ctx);
220 HygieneData::with(|data| {
221 let old_expn_data = &mut data.local_expn_data[self];
222 assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
223 *old_expn_data = Some(expn_data);
224 debug_assert_eq!(data.local_expn_hashes[self].0, Fingerprint::ZERO);
225 data.local_expn_hashes[self] = expn_hash;
226 let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, self.to_expn_id());
227 debug_assert!(_old_id.is_none());
232 pub fn is_descendant_of(self, ancestor: LocalExpnId) -> bool {
233 self.to_expn_id().is_descendant_of(ancestor.to_expn_id())
236 /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
237 /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
239 pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
240 self.to_expn_id().outer_expn_is_descendant_of(ctxt)
243 /// Returns span for the macro which originally caused this expansion to happen.
245 /// Stops backtracing at include! boundary.
247 pub fn expansion_cause(self) -> Option<Span> {
248 self.to_expn_id().expansion_cause()
253 pub fn parent(self) -> LocalExpnId {
254 self.expn_data().parent.as_local().unwrap()
259 /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
260 /// Invariant: we do not create any ExpnId with local_id == 0 and krate != 0.
261 pub const fn root() -> ExpnId {
262 ExpnId { krate: LOCAL_CRATE, local_id: ExpnIndex::from_u32(0) }
266 pub fn expn_hash(self) -> ExpnHash {
267 HygieneData::with(|data| data.expn_hash(self))
271 pub fn from_hash(hash: ExpnHash) -> Option<ExpnId> {
272 HygieneData::with(|data| data.expn_hash_to_expn_id.get(&hash).copied())
276 pub fn as_local(self) -> Option<LocalExpnId> {
277 if self.krate == LOCAL_CRATE { Some(LocalExpnId::from_raw(self.local_id)) } else { None }
282 pub fn expect_local(self) -> LocalExpnId {
283 self.as_local().unwrap()
287 pub fn expn_data(self) -> ExpnData {
288 HygieneData::with(|data| data.expn_data(self).clone())
292 pub fn is_descendant_of(self, ancestor: ExpnId) -> bool {
293 // a few "fast path" cases to avoid locking HygieneData
294 if ancestor == ExpnId::root() || ancestor == self {
297 if ancestor.krate != self.krate {
300 HygieneData::with(|data| data.is_descendant_of(self, ancestor))
303 /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
304 /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
305 pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
306 HygieneData::with(|data| data.is_descendant_of(self, data.outer_expn(ctxt)))
309 /// Returns span for the macro which originally caused this expansion to happen.
311 /// Stops backtracing at include! boundary.
312 pub fn expansion_cause(mut self) -> Option<Span> {
313 let mut last_macro = None;
315 let expn_data = self.expn_data();
316 // Stop going up the backtrace once include! is encountered
317 if expn_data.is_root()
318 || expn_data.kind == ExpnKind::Macro(MacroKind::Bang, sym::include)
322 self = expn_data.call_site.ctxt().outer_expn();
323 last_macro = Some(expn_data.call_site);
330 pub struct HygieneData {
331 /// Each expansion should have an associated expansion data, but sometimes there's a delay
332 /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
333 /// first and then resolved later), so we use an `Option` here.
334 local_expn_data: IndexVec<LocalExpnId, Option<ExpnData>>,
335 local_expn_hashes: IndexVec<LocalExpnId, ExpnHash>,
336 /// Data and hash information from external crates. We may eventually want to remove these
337 /// maps, and fetch the information directly from the other crate's metadata like DefIds do.
338 foreign_expn_data: FxHashMap<ExpnId, ExpnData>,
339 foreign_expn_hashes: FxHashMap<ExpnId, ExpnHash>,
340 expn_hash_to_expn_id: UnhashMap<ExpnHash, ExpnId>,
341 syntax_context_data: Vec<SyntaxContextData>,
342 syntax_context_map: FxHashMap<(SyntaxContext, ExpnId, Transparency), SyntaxContext>,
343 /// Maps the `local_hash` of an `ExpnData` to the next disambiguator value.
344 /// This is used by `update_disambiguator` to keep track of which `ExpnData`s
345 /// would have collisions without a disambiguator.
346 /// The keys of this map are always computed with `ExpnData.disambiguator`
348 expn_data_disambiguators: FxHashMap<u64, u32>,
352 pub(crate) fn new(edition: Edition) -> Self {
353 let root_data = ExpnData::default(
357 Some(CRATE_DEF_ID.to_def_id()),
362 local_expn_data: IndexVec::from_elem_n(Some(root_data), 1),
363 local_expn_hashes: IndexVec::from_elem_n(ExpnHash(Fingerprint::ZERO), 1),
364 foreign_expn_data: FxHashMap::default(),
365 foreign_expn_hashes: FxHashMap::default(),
366 expn_hash_to_expn_id: std::iter::once((ExpnHash(Fingerprint::ZERO), ExpnId::root()))
368 syntax_context_data: vec![SyntaxContextData {
369 outer_expn: ExpnId::root(),
370 outer_transparency: Transparency::Opaque,
371 parent: SyntaxContext(0),
372 opaque: SyntaxContext(0),
373 opaque_and_semitransparent: SyntaxContext(0),
374 dollar_crate_name: kw::DollarCrate,
376 syntax_context_map: FxHashMap::default(),
377 expn_data_disambiguators: FxHashMap::default(),
381 pub fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
382 with_session_globals(|session_globals| f(&mut session_globals.hygiene_data.borrow_mut()))
386 fn local_expn_hash(&self, expn_id: LocalExpnId) -> ExpnHash {
387 self.local_expn_hashes[expn_id]
391 fn expn_hash(&self, expn_id: ExpnId) -> ExpnHash {
392 match expn_id.as_local() {
393 Some(expn_id) => self.local_expn_hashes[expn_id],
394 None => self.foreign_expn_hashes[&expn_id],
398 fn local_expn_data(&self, expn_id: LocalExpnId) -> &ExpnData {
399 self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
402 fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
403 if let Some(expn_id) = expn_id.as_local() {
404 self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
406 &self.foreign_expn_data[&expn_id]
410 fn is_descendant_of(&self, mut expn_id: ExpnId, ancestor: ExpnId) -> bool {
411 // a couple "fast path" cases to avoid traversing parents in the loop below
412 if ancestor == ExpnId::root() {
415 if expn_id.krate != ancestor.krate {
419 if expn_id == ancestor {
422 if expn_id == ExpnId::root() {
425 expn_id = self.expn_data(expn_id).parent;
429 fn normalize_to_macros_2_0(&self, ctxt: SyntaxContext) -> SyntaxContext {
430 self.syntax_context_data[ctxt.0 as usize].opaque
433 fn normalize_to_macro_rules(&self, ctxt: SyntaxContext) -> SyntaxContext {
434 self.syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent
437 fn outer_expn(&self, ctxt: SyntaxContext) -> ExpnId {
438 self.syntax_context_data[ctxt.0 as usize].outer_expn
441 fn outer_mark(&self, ctxt: SyntaxContext) -> (ExpnId, Transparency) {
442 let data = &self.syntax_context_data[ctxt.0 as usize];
443 (data.outer_expn, data.outer_transparency)
446 fn parent_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext {
447 self.syntax_context_data[ctxt.0 as usize].parent
450 fn remove_mark(&self, ctxt: &mut SyntaxContext) -> (ExpnId, Transparency) {
451 let outer_mark = self.outer_mark(*ctxt);
452 *ctxt = self.parent_ctxt(*ctxt);
456 fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
457 let mut marks = Vec::new();
458 while ctxt != SyntaxContext::root() {
459 debug!("marks: getting parent of {:?}", ctxt);
460 marks.push(self.outer_mark(ctxt));
461 ctxt = self.parent_ctxt(ctxt);
467 fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span {
468 debug!("walk_chain({:?}, {:?})", span, to);
469 debug!("walk_chain: span ctxt = {:?}", span.ctxt());
470 while span.from_expansion() && span.ctxt() != to {
471 let outer_expn = self.outer_expn(span.ctxt());
472 debug!("walk_chain({:?}): outer_expn={:?}", span, outer_expn);
473 let expn_data = self.expn_data(outer_expn);
474 debug!("walk_chain({:?}): expn_data={:?}", span, expn_data);
475 span = expn_data.call_site;
480 fn adjust(&self, ctxt: &mut SyntaxContext, expn_id: ExpnId) -> Option<ExpnId> {
481 let mut scope = None;
482 while !self.is_descendant_of(expn_id, self.outer_expn(*ctxt)) {
483 scope = Some(self.remove_mark(ctxt).0);
492 transparency: Transparency,
494 assert_ne!(expn_id, ExpnId::root());
495 if transparency == Transparency::Opaque {
496 return self.apply_mark_internal(ctxt, expn_id, transparency);
499 let call_site_ctxt = self.expn_data(expn_id).call_site.ctxt();
500 let mut call_site_ctxt = if transparency == Transparency::SemiTransparent {
501 self.normalize_to_macros_2_0(call_site_ctxt)
503 self.normalize_to_macro_rules(call_site_ctxt)
506 if call_site_ctxt == SyntaxContext::root() {
507 return self.apply_mark_internal(ctxt, expn_id, transparency);
510 // Otherwise, `expn_id` is a macros 1.0 definition and the call site is in a
511 // macros 2.0 expansion, i.e., a macros 1.0 invocation is in a macros 2.0 definition.
513 // In this case, the tokens from the macros 1.0 definition inherit the hygiene
514 // at their invocation. That is, we pretend that the macros 1.0 definition
515 // was defined at its invocation (i.e., inside the macros 2.0 definition)
516 // so that the macros 2.0 definition remains hygienic.
518 // See the example at `test/ui/hygiene/legacy_interaction.rs`.
519 for (expn_id, transparency) in self.marks(ctxt) {
520 call_site_ctxt = self.apply_mark_internal(call_site_ctxt, expn_id, transparency);
522 self.apply_mark_internal(call_site_ctxt, expn_id, transparency)
525 fn apply_mark_internal(
529 transparency: Transparency,
531 let syntax_context_data = &mut self.syntax_context_data;
532 let mut opaque = syntax_context_data[ctxt.0 as usize].opaque;
533 let mut opaque_and_semitransparent =
534 syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent;
536 if transparency >= Transparency::Opaque {
540 .entry((parent, expn_id, transparency))
542 let new_opaque = SyntaxContext(syntax_context_data.len() as u32);
543 syntax_context_data.push(SyntaxContextData {
545 outer_transparency: transparency,
548 opaque_and_semitransparent: new_opaque,
549 dollar_crate_name: kw::DollarCrate,
555 if transparency >= Transparency::SemiTransparent {
556 let parent = opaque_and_semitransparent;
557 opaque_and_semitransparent = *self
559 .entry((parent, expn_id, transparency))
561 let new_opaque_and_semitransparent =
562 SyntaxContext(syntax_context_data.len() as u32);
563 syntax_context_data.push(SyntaxContextData {
565 outer_transparency: transparency,
568 opaque_and_semitransparent: new_opaque_and_semitransparent,
569 dollar_crate_name: kw::DollarCrate,
571 new_opaque_and_semitransparent
576 *self.syntax_context_map.entry((parent, expn_id, transparency)).or_insert_with(|| {
577 let new_opaque_and_semitransparent_and_transparent =
578 SyntaxContext(syntax_context_data.len() as u32);
579 syntax_context_data.push(SyntaxContextData {
581 outer_transparency: transparency,
584 opaque_and_semitransparent,
585 dollar_crate_name: kw::DollarCrate,
587 new_opaque_and_semitransparent_and_transparent
592 pub fn clear_syntax_context_map() {
593 HygieneData::with(|data| data.syntax_context_map = FxHashMap::default());
596 pub fn walk_chain(span: Span, to: SyntaxContext) -> Span {
597 HygieneData::with(|data| data.walk_chain(span, to))
600 pub fn update_dollar_crate_names(mut get_name: impl FnMut(SyntaxContext) -> Symbol) {
601 // The new contexts that need updating are at the end of the list and have `$crate` as a name.
602 let (len, to_update) = HygieneData::with(|data| {
604 data.syntax_context_data.len(),
605 data.syntax_context_data
608 .take_while(|scdata| scdata.dollar_crate_name == kw::DollarCrate)
612 // The callback must be called from outside of the `HygieneData` lock,
613 // since it will try to acquire it too.
614 let range_to_update = len - to_update..len;
616 range_to_update.clone().map(|idx| get_name(SyntaxContext::from_u32(idx as u32))).collect();
617 HygieneData::with(|data| {
618 range_to_update.zip(names).for_each(|(idx, name)| {
619 data.syntax_context_data[idx].dollar_crate_name = name;
624 pub fn debug_hygiene_data(verbose: bool) -> String {
625 HygieneData::with(|data| {
627 format!("{:#?}", data)
629 let mut s = String::from("Expansions:");
630 let mut debug_expn_data = |(id, expn_data): (&ExpnId, &ExpnData)| {
632 "\n{:?}: parent: {:?}, call_site_ctxt: {:?}, def_site_ctxt: {:?}, kind: {:?}",
635 expn_data.call_site.ctxt(),
636 expn_data.def_site.ctxt(),
640 data.local_expn_data.iter_enumerated().for_each(|(id, expn_data)| {
641 let expn_data = expn_data.as_ref().expect("no expansion data for an expansion ID");
642 debug_expn_data((&id.to_expn_id(), expn_data))
645 // Sort the hash map for more reproducible output.
646 // Because of this, it is fine to rely on the unstable iteration order of the map.
647 #[allow(rustc::potential_query_instability)]
648 let mut foreign_expn_data: Vec<_> = data.foreign_expn_data.iter().collect();
649 foreign_expn_data.sort_by_key(|(id, _)| (id.krate, id.local_id));
650 foreign_expn_data.into_iter().for_each(debug_expn_data);
651 s.push_str("\n\nSyntaxContexts:");
652 data.syntax_context_data.iter().enumerate().for_each(|(id, ctxt)| {
654 "\n#{}: parent: {:?}, outer_mark: ({:?}, {:?})",
655 id, ctxt.parent, ctxt.outer_expn, ctxt.outer_transparency,
665 pub const fn root() -> Self {
670 pub(crate) fn as_u32(self) -> u32 {
675 pub(crate) fn from_u32(raw: u32) -> SyntaxContext {
679 /// Extend a syntax context with a given expansion and transparency.
680 pub(crate) fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext {
681 HygieneData::with(|data| data.apply_mark(self, expn_id, transparency))
684 /// Pulls a single mark off of the syntax context. This effectively moves the
685 /// context up one macro definition level. That is, if we have a nested macro
686 /// definition as follows:
688 /// ```ignore (illustrative)
696 /// and we have a SyntaxContext that is referring to something declared by an invocation
697 /// of g (call it g1), calling remove_mark will result in the SyntaxContext for the
698 /// invocation of f that created g1.
699 /// Returns the mark that was removed.
700 pub fn remove_mark(&mut self) -> ExpnId {
701 HygieneData::with(|data| data.remove_mark(self).0)
704 pub fn marks(self) -> Vec<(ExpnId, Transparency)> {
705 HygieneData::with(|data| data.marks(self))
708 /// Adjust this context for resolution in a scope created by the given expansion.
709 /// For example, consider the following three resolutions of `f`:
712 /// #![feature(decl_macro)]
713 /// mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
715 /// macro m($f:ident) {
717 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
718 /// pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
720 /// foo::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
721 /// //^ Since `mod foo` is outside this expansion, `adjust` removes the mark from `f`,
722 /// //| and it resolves to `::foo::f`.
723 /// bar::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
724 /// //^ Since `mod bar` not outside this expansion, `adjust` does not change `f`,
725 /// //| and it resolves to `::bar::f`.
726 /// bar::$f(); // `f`'s `SyntaxContext` is empty.
727 /// //^ Since `mod bar` is not outside this expansion, `adjust` does not change `$f`,
728 /// //| and it resolves to `::bar::$f`.
731 /// This returns the expansion whose definition scope we use to privacy check the resolution,
732 /// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope).
733 pub fn adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
734 HygieneData::with(|data| data.adjust(self, expn_id))
737 /// Like `SyntaxContext::adjust`, but also normalizes `self` to macros 2.0.
738 pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
739 HygieneData::with(|data| {
740 *self = data.normalize_to_macros_2_0(*self);
741 data.adjust(self, expn_id)
745 /// Adjust this context for resolution in a scope created by the given expansion
746 /// via a glob import with the given `SyntaxContext`.
749 /// ```compile_fail,E0425
750 /// #![feature(decl_macro)]
752 /// macro m($i:ident) {
754 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
755 /// pub fn $i() {} // `$i`'s `SyntaxContext` is empty.
758 /// macro n($j:ident) {
760 /// f(); // `f`'s `SyntaxContext` has a mark from `m` and a mark from `n`
761 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::f`.
762 /// $i(); // `$i`'s `SyntaxContext` has a mark from `n`
763 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::$i`.
764 /// $j(); // `$j`'s `SyntaxContext` has a mark from `m`
765 /// //^ This cannot be glob-adjusted, so this is a resolution error.
769 /// This returns `None` if the context cannot be glob-adjusted.
770 /// Otherwise, it returns the scope to use when privacy checking (see `adjust` for details).
771 pub fn glob_adjust(&mut self, expn_id: ExpnId, glob_span: Span) -> Option<Option<ExpnId>> {
772 HygieneData::with(|data| {
773 let mut scope = None;
774 let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
775 while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
776 scope = Some(data.remove_mark(&mut glob_ctxt).0);
777 if data.remove_mark(self).0 != scope.unwrap() {
781 if data.adjust(self, expn_id).is_some() {
788 /// Undo `glob_adjust` if possible:
790 /// ```ignore (illustrative)
791 /// if let Some(privacy_checking_scope) = self.reverse_glob_adjust(expansion, glob_ctxt) {
792 /// assert!(self.glob_adjust(expansion, glob_ctxt) == Some(privacy_checking_scope));
795 pub fn reverse_glob_adjust(
799 ) -> Option<Option<ExpnId>> {
800 HygieneData::with(|data| {
801 if data.adjust(self, expn_id).is_some() {
805 let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
806 let mut marks = Vec::new();
807 while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
808 marks.push(data.remove_mark(&mut glob_ctxt));
811 let scope = marks.last().map(|mark| mark.0);
812 while let Some((expn_id, transparency)) = marks.pop() {
813 *self = data.apply_mark(*self, expn_id, transparency);
819 pub fn hygienic_eq(self, other: SyntaxContext, expn_id: ExpnId) -> bool {
820 HygieneData::with(|data| {
821 let mut self_normalized = data.normalize_to_macros_2_0(self);
822 data.adjust(&mut self_normalized, expn_id);
823 self_normalized == data.normalize_to_macros_2_0(other)
828 pub fn normalize_to_macros_2_0(self) -> SyntaxContext {
829 HygieneData::with(|data| data.normalize_to_macros_2_0(self))
833 pub fn normalize_to_macro_rules(self) -> SyntaxContext {
834 HygieneData::with(|data| data.normalize_to_macro_rules(self))
838 pub fn outer_expn(self) -> ExpnId {
839 HygieneData::with(|data| data.outer_expn(self))
842 /// `ctxt.outer_expn_data()` is equivalent to but faster than
843 /// `ctxt.outer_expn().expn_data()`.
845 pub fn outer_expn_data(self) -> ExpnData {
846 HygieneData::with(|data| data.expn_data(data.outer_expn(self)).clone())
850 pub fn outer_mark(self) -> (ExpnId, Transparency) {
851 HygieneData::with(|data| data.outer_mark(self))
854 pub fn dollar_crate_name(self) -> Symbol {
855 HygieneData::with(|data| data.syntax_context_data[self.0 as usize].dollar_crate_name)
858 pub fn edition(self) -> Edition {
859 HygieneData::with(|data| data.expn_data(data.outer_expn(self)).edition)
863 impl fmt::Debug for SyntaxContext {
864 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
865 write!(f, "#{}", self.0)
870 /// Creates a fresh expansion with given properties.
871 /// Expansions are normally created by macros, but in some cases expansions are created for
872 /// other compiler-generated code to set per-span properties like allowed unstable features.
873 /// The returned span belongs to the created expansion and has the new properties,
874 /// but its location is inherited from the current span.
875 pub fn fresh_expansion(self, expn_id: LocalExpnId) -> Span {
876 HygieneData::with(|data| {
877 self.with_ctxt(data.apply_mark(
878 SyntaxContext::root(),
879 expn_id.to_expn_id(),
880 Transparency::Transparent,
885 /// Reuses the span but adds information like the kind of the desugaring and features that are
886 /// allowed inside this span.
887 pub fn mark_with_reason(
889 allow_internal_unstable: Option<Lrc<[Symbol]>>,
890 reason: DesugaringKind,
892 ctx: impl HashStableContext,
894 let expn_data = ExpnData {
895 allow_internal_unstable,
896 ..ExpnData::default(ExpnKind::Desugaring(reason), self, edition, None, None)
898 let expn_id = LocalExpnId::fresh(expn_data, ctx);
899 self.fresh_expansion(expn_id)
903 /// A subset of properties from both macro definition and macro call available through global data.
904 /// Avoid using this if you have access to the original definition or call structures.
905 #[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
906 pub struct ExpnData {
907 // --- The part unique to each expansion.
908 /// The kind of this expansion - macro or compiler desugaring.
910 /// The expansion that produced this expansion.
912 /// The location of the actual macro invocation or syntax sugar , e.g.
913 /// `let x = foo!();` or `if let Some(y) = x {}`
915 /// This may recursively refer to other macro invocations, e.g., if
916 /// `foo!()` invoked `bar!()` internally, and there was an
917 /// expression inside `bar!`; the call_site of the expression in
918 /// the expansion would point to the `bar!` invocation; that
919 /// call_site span would have its own ExpnData, with the call_site
920 /// pointing to the `foo!` invocation.
922 /// Used to force two `ExpnData`s to have different `Fingerprint`s.
923 /// Due to macro expansion, it's possible to end up with two `ExpnId`s
924 /// that have identical `ExpnData`s. This violates the contract of `HashStable`
925 /// - the two `ExpnId`s are not equal, but their `Fingerprint`s are equal
926 /// (since the numerical `ExpnId` value is not considered by the `HashStable`
929 /// The `disambiguator` field is set by `update_disambiguator` when two distinct
930 /// `ExpnId`s would end up with the same `Fingerprint`. Since `ExpnData` includes
931 /// a `krate` field, this value only needs to be unique within a single crate.
934 // --- The part specific to the macro/desugaring definition.
935 // --- It may be reasonable to share this part between expansions with the same definition,
936 // --- but such sharing is known to bring some minor inconveniences without also bringing
937 // --- noticeable perf improvements (PR #62898).
938 /// The span of the macro definition (possibly dummy).
939 /// This span serves only informational purpose and is not used for resolution.
941 /// List of `#[unstable]`/feature-gated features that the macro is allowed to use
942 /// internally without forcing the whole crate to opt-in
944 pub allow_internal_unstable: Option<Lrc<[Symbol]>>,
945 /// Edition of the crate in which the macro is defined.
946 pub edition: Edition,
947 /// The `DefId` of the macro being invoked,
948 /// if this `ExpnData` corresponds to a macro invocation
949 pub macro_def_id: Option<DefId>,
950 /// The normal module (`mod`) in which the expanded macro was defined.
951 pub parent_module: Option<DefId>,
952 /// Suppresses the `unsafe_code` lint for code produced by this macro.
953 pub allow_internal_unsafe: bool,
954 /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`) for this macro.
955 pub local_inner_macros: bool,
956 /// Should debuginfo for the macro be collapsed to the outermost expansion site (in other
957 /// words, was the macro definition annotated with `#[collapse_debuginfo]`)?
958 pub collapse_debuginfo: bool,
961 impl !PartialEq for ExpnData {}
962 impl !Hash for ExpnData {}
970 allow_internal_unstable: Option<Lrc<[Symbol]>>,
972 macro_def_id: Option<DefId>,
973 parent_module: Option<DefId>,
974 allow_internal_unsafe: bool,
975 local_inner_macros: bool,
976 collapse_debuginfo: bool,
983 allow_internal_unstable,
988 allow_internal_unsafe,
994 /// Constructs expansion data with default properties.
999 macro_def_id: Option<DefId>,
1000 parent_module: Option<DefId>,
1004 parent: ExpnId::root(),
1007 allow_internal_unstable: None,
1012 allow_internal_unsafe: false,
1013 local_inner_macros: false,
1014 collapse_debuginfo: false,
1018 pub fn allow_unstable(
1022 allow_internal_unstable: Lrc<[Symbol]>,
1023 macro_def_id: Option<DefId>,
1024 parent_module: Option<DefId>,
1027 allow_internal_unstable: Some(allow_internal_unstable),
1028 ..ExpnData::default(kind, call_site, edition, macro_def_id, parent_module)
1033 pub fn is_root(&self) -> bool {
1034 matches!(self.kind, ExpnKind::Root)
1038 fn hash_expn(&self, ctx: &mut impl HashStableContext) -> u64 {
1039 let mut hasher = StableHasher::new();
1040 self.hash_stable(ctx, &mut hasher);
1046 #[derive(Clone, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
1048 /// No expansion, aka root expansion. Only `ExpnId::root()` has this kind.
1050 /// Expansion produced by a macro.
1051 Macro(MacroKind, Symbol),
1052 /// Transform done by the compiler on the AST.
1054 /// Desugaring done by the compiler during HIR lowering.
1055 Desugaring(DesugaringKind),
1061 pub fn descr(&self) -> String {
1063 ExpnKind::Root => kw::PathRoot.to_string(),
1064 ExpnKind::Macro(macro_kind, name) => match macro_kind {
1065 MacroKind::Bang => format!("{}!", name),
1066 MacroKind::Attr => format!("#[{}]", name),
1067 MacroKind::Derive => format!("#[derive({})]", name),
1069 ExpnKind::AstPass(kind) => kind.descr().to_string(),
1070 ExpnKind::Desugaring(kind) => format!("desugaring of {}", kind.descr()),
1071 ExpnKind::Inlined => "inlined source".to_string(),
1076 /// The kind of macro invocation or definition.
1077 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
1078 #[derive(HashStable_Generic)]
1079 pub enum MacroKind {
1080 /// A bang macro `foo!()`.
1082 /// An attribute macro `#[foo]`.
1084 /// A derive macro `#[derive(Foo)]`
1089 pub fn descr(self) -> &'static str {
1091 MacroKind::Bang => "macro",
1092 MacroKind::Attr => "attribute macro",
1093 MacroKind::Derive => "derive macro",
1097 pub fn descr_expected(self) -> &'static str {
1099 MacroKind::Attr => "attribute",
1104 pub fn article(self) -> &'static str {
1106 MacroKind::Attr => "an",
1112 /// The kind of AST transform.
1113 #[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
1121 pub fn descr(self) -> &'static str {
1123 AstPass::StdImports => "standard library imports",
1124 AstPass::TestHarness => "test harness",
1125 AstPass::ProcMacroHarness => "proc macro harness",
1130 /// The kind of compiler desugaring.
1131 #[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
1132 pub enum DesugaringKind {
1133 /// We desugar `if c { i } else { e }` to `match $ExprKind::Use(c) { true => i, _ => e }`.
1134 /// However, we do not want to blame `c` for unreachability but rather say that `i`
1135 /// is unreachable. This desugaring kind allows us to avoid blaming `c`.
1136 /// This also applies to `while` loops.
1141 /// Desugaring of an `impl Trait` in return type position
1142 /// to an `type Foo = impl Trait;` and replacing the
1143 /// `impl Trait` with `Foo`.
1151 impl DesugaringKind {
1152 /// The description wording should combine well with "desugaring of {}".
1153 pub fn descr(self) -> &'static str {
1155 DesugaringKind::CondTemporary => "`if` or `while` condition",
1156 DesugaringKind::Async => "`async` block or function",
1157 DesugaringKind::Await => "`await` expression",
1158 DesugaringKind::QuestionMark => "operator `?`",
1159 DesugaringKind::TryBlock => "`try` block",
1160 DesugaringKind::YeetExpr => "`do yeet` expression",
1161 DesugaringKind::OpaqueTy => "`impl Trait`",
1162 DesugaringKind::ForLoop => "`for` loop",
1163 DesugaringKind::WhileLoop => "`while` loop",
1169 pub struct HygieneEncodeContext {
1170 /// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
1171 /// This is `None` after we finish encoding `SyntaxContexts`, to ensure
1172 /// that we don't accidentally try to encode any more `SyntaxContexts`
1173 serialized_ctxts: Lock<FxHashSet<SyntaxContext>>,
1174 /// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
1175 /// in the most recent 'round' of serializing. Serializing `SyntaxContextData`
1176 /// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
1177 /// until we reach a fixed point.
1178 latest_ctxts: Lock<FxHashSet<SyntaxContext>>,
1180 serialized_expns: Lock<FxHashSet<ExpnId>>,
1182 latest_expns: Lock<FxHashSet<ExpnId>>,
1185 impl HygieneEncodeContext {
1186 /// Record the fact that we need to serialize the corresponding `ExpnData`.
1187 pub fn schedule_expn_data_for_encoding(&self, expn: ExpnId) {
1188 if !self.serialized_expns.lock().contains(&expn) {
1189 self.latest_expns.lock().insert(expn);
1196 mut encode_ctxt: impl FnMut(&mut T, u32, &SyntaxContextData),
1197 mut encode_expn: impl FnMut(&mut T, ExpnId, &ExpnData, ExpnHash),
1199 // When we serialize a `SyntaxContextData`, we may end up serializing
1200 // a `SyntaxContext` that we haven't seen before
1201 while !self.latest_ctxts.lock().is_empty() || !self.latest_expns.lock().is_empty() {
1203 "encode_hygiene: Serializing a round of {:?} SyntaxContextDatas: {:?}",
1204 self.latest_ctxts.lock().len(),
1208 // Consume the current round of SyntaxContexts.
1209 // Drop the lock() temporary early
1210 let latest_ctxts = { std::mem::take(&mut *self.latest_ctxts.lock()) };
1212 // It's fine to iterate over a HashMap, because the serialization
1213 // of the table that we insert data into doesn't depend on insertion
1215 #[allow(rustc::potential_query_instability)]
1216 for_all_ctxts_in(latest_ctxts.into_iter(), |index, ctxt, data| {
1217 if self.serialized_ctxts.lock().insert(ctxt) {
1218 encode_ctxt(encoder, index, data);
1222 let latest_expns = { std::mem::take(&mut *self.latest_expns.lock()) };
1224 // Same as above, this is fine as we are inserting into a order-independent hashset
1225 #[allow(rustc::potential_query_instability)]
1226 for_all_expns_in(latest_expns.into_iter(), |expn, data, hash| {
1227 if self.serialized_expns.lock().insert(expn) {
1228 encode_expn(encoder, expn, data, hash);
1232 debug!("encode_hygiene: Done serializing SyntaxContextData");
1237 /// Additional information used to assist in decoding hygiene data
1238 pub struct HygieneDecodeContext {
1239 // Maps serialized `SyntaxContext` ids to a `SyntaxContext` in the current
1240 // global `HygieneData`. When we deserialize a `SyntaxContext`, we need to create
1241 // a new id in the global `HygieneData`. This map tracks the ID we end up picking,
1242 // so that multiple occurrences of the same serialized id are decoded to the same
1244 remapped_ctxts: Lock<Vec<Option<SyntaxContext>>>,
1247 /// Register an expansion which has been decoded from the on-disk-cache for the local crate.
1248 pub fn register_local_expn_id(data: ExpnData, hash: ExpnHash) -> ExpnId {
1249 HygieneData::with(|hygiene_data| {
1250 let expn_id = hygiene_data.local_expn_data.next_index();
1251 hygiene_data.local_expn_data.push(Some(data));
1252 let _eid = hygiene_data.local_expn_hashes.push(hash);
1253 debug_assert_eq!(expn_id, _eid);
1255 let expn_id = expn_id.to_expn_id();
1257 let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
1258 debug_assert!(_old_id.is_none());
1263 /// Register an expansion which has been decoded from the metadata of a foreign crate.
1264 pub fn register_expn_id(
1266 local_id: ExpnIndex,
1270 debug_assert!(data.parent == ExpnId::root() || krate == data.parent.krate);
1271 let expn_id = ExpnId { krate, local_id };
1272 HygieneData::with(|hygiene_data| {
1273 let _old_data = hygiene_data.foreign_expn_data.insert(expn_id, data);
1274 debug_assert!(_old_data.is_none());
1275 let _old_hash = hygiene_data.foreign_expn_hashes.insert(expn_id, hash);
1276 debug_assert!(_old_hash.is_none());
1277 let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
1278 debug_assert!(_old_id.is_none());
1283 /// Decode an expansion from the metadata of a foreign crate.
1284 pub fn decode_expn_id(
1287 decode_data: impl FnOnce(ExpnId) -> (ExpnData, ExpnHash),
1290 debug!("decode_expn_id: deserialized root");
1291 return ExpnId::root();
1294 let index = ExpnIndex::from_u32(index);
1296 // This function is used to decode metadata, so it cannot decode information about LOCAL_CRATE.
1297 debug_assert_ne!(krate, LOCAL_CRATE);
1298 let expn_id = ExpnId { krate, local_id: index };
1300 // Fast path if the expansion has already been decoded.
1301 if HygieneData::with(|hygiene_data| hygiene_data.foreign_expn_data.contains_key(&expn_id)) {
1305 // Don't decode the data inside `HygieneData::with`, since we need to recursively decode
1307 let (expn_data, hash) = decode_data(expn_id);
1309 register_expn_id(krate, index, expn_data, hash)
1312 // Decodes `SyntaxContext`, using the provided `HygieneDecodeContext`
1313 // to track which `SyntaxContext`s we have already decoded.
1314 // The provided closure will be invoked to deserialize a `SyntaxContextData`
1315 // if we haven't already seen the id of the `SyntaxContext` we are deserializing.
1316 pub fn decode_syntax_context<D: Decoder, F: FnOnce(&mut D, u32) -> SyntaxContextData>(
1318 context: &HygieneDecodeContext,
1320 ) -> SyntaxContext {
1321 let raw_id: u32 = Decodable::decode(d);
1323 debug!("decode_syntax_context: deserialized root");
1324 // The root is special
1325 return SyntaxContext::root();
1328 let outer_ctxts = &context.remapped_ctxts;
1330 // Ensure that the lock() temporary is dropped early
1332 if let Some(ctxt) = outer_ctxts.lock().get(raw_id as usize).copied().flatten() {
1337 // Allocate and store SyntaxContext id *before* calling the decoder function,
1338 // as the SyntaxContextData may reference itself.
1339 let new_ctxt = HygieneData::with(|hygiene_data| {
1340 let new_ctxt = SyntaxContext(hygiene_data.syntax_context_data.len() as u32);
1341 // Push a dummy SyntaxContextData to ensure that nobody else can get the
1342 // same ID as us. This will be overwritten after call `decode_Data`
1343 hygiene_data.syntax_context_data.push(SyntaxContextData {
1344 outer_expn: ExpnId::root(),
1345 outer_transparency: Transparency::Transparent,
1346 parent: SyntaxContext::root(),
1347 opaque: SyntaxContext::root(),
1348 opaque_and_semitransparent: SyntaxContext::root(),
1349 dollar_crate_name: kw::Empty,
1351 let mut ctxts = outer_ctxts.lock();
1352 let new_len = raw_id as usize + 1;
1353 if ctxts.len() < new_len {
1354 ctxts.resize(new_len, None);
1356 ctxts[raw_id as usize] = Some(new_ctxt);
1361 // Don't try to decode data while holding the lock, since we need to
1362 // be able to recursively decode a SyntaxContext
1363 let mut ctxt_data = decode_data(d, raw_id);
1364 // Reset `dollar_crate_name` so that it will be updated by `update_dollar_crate_names`
1365 // We don't care what the encoding crate set this to - we want to resolve it
1366 // from the perspective of the current compilation session
1367 ctxt_data.dollar_crate_name = kw::DollarCrate;
1369 // Overwrite the dummy data with our decoded SyntaxContextData
1370 HygieneData::with(|hygiene_data| {
1371 let dummy = std::mem::replace(
1372 &mut hygiene_data.syntax_context_data[new_ctxt.as_u32() as usize],
1375 // Make sure nothing weird happening while `decode_data` was running
1376 assert_eq!(dummy.dollar_crate_name, kw::Empty);
1382 fn for_all_ctxts_in<F: FnMut(u32, SyntaxContext, &SyntaxContextData)>(
1383 ctxts: impl Iterator<Item = SyntaxContext>,
1386 let all_data: Vec<_> = HygieneData::with(|data| {
1387 ctxts.map(|ctxt| (ctxt, data.syntax_context_data[ctxt.0 as usize].clone())).collect()
1389 for (ctxt, data) in all_data.into_iter() {
1390 f(ctxt.0, ctxt, &data);
1394 fn for_all_expns_in(
1395 expns: impl Iterator<Item = ExpnId>,
1396 mut f: impl FnMut(ExpnId, &ExpnData, ExpnHash),
1398 let all_data: Vec<_> = HygieneData::with(|data| {
1399 expns.map(|expn| (expn, data.expn_data(expn).clone(), data.expn_hash(expn))).collect()
1401 for (expn, data, hash) in all_data.into_iter() {
1402 f(expn, &data, hash);
1406 impl<E: Encoder> Encodable<E> for LocalExpnId {
1407 fn encode(&self, e: &mut E) {
1408 self.to_expn_id().encode(e);
1412 impl<E: Encoder> Encodable<E> for ExpnId {
1413 default fn encode(&self, _: &mut E) {
1414 panic!("cannot encode `ExpnId` with `{}`", std::any::type_name::<E>());
1418 impl<D: Decoder> Decodable<D> for LocalExpnId {
1419 fn decode(d: &mut D) -> Self {
1420 ExpnId::expect_local(ExpnId::decode(d))
1424 impl<D: Decoder> Decodable<D> for ExpnId {
1425 default fn decode(_: &mut D) -> Self {
1426 panic!("cannot decode `ExpnId` with `{}`", std::any::type_name::<D>());
1430 pub fn raw_encode_syntax_context<E: Encoder>(
1431 ctxt: SyntaxContext,
1432 context: &HygieneEncodeContext,
1435 if !context.serialized_ctxts.lock().contains(&ctxt) {
1436 context.latest_ctxts.lock().insert(ctxt);
1441 impl<E: Encoder> Encodable<E> for SyntaxContext {
1442 default fn encode(&self, _: &mut E) {
1443 panic!("cannot encode `SyntaxContext` with `{}`", std::any::type_name::<E>());
1447 impl<D: Decoder> Decodable<D> for SyntaxContext {
1448 default fn decode(_: &mut D) -> Self {
1449 panic!("cannot decode `SyntaxContext` with `{}`", std::any::type_name::<D>());
1453 /// Updates the `disambiguator` field of the corresponding `ExpnData`
1454 /// such that the `Fingerprint` of the `ExpnData` does not collide with
1455 /// any other `ExpnIds`.
1457 /// This method is called only when an `ExpnData` is first associated
1458 /// with an `ExpnId` (when the `ExpnId` is initially constructed, or via
1459 /// `set_expn_data`). It is *not* called for foreign `ExpnId`s deserialized
1460 /// from another crate's metadata - since `ExpnHash` includes the stable crate id,
1461 /// collisions are only possible between `ExpnId`s within the same crate.
1462 fn update_disambiguator(expn_data: &mut ExpnData, mut ctx: impl HashStableContext) -> ExpnHash {
1463 // This disambiguator should not have been set yet.
1465 expn_data.disambiguator, 0,
1466 "Already set disambiguator for ExpnData: {:?}",
1469 assert_default_hashing_controls(&ctx, "ExpnData (disambiguator)");
1470 let mut expn_hash = expn_data.hash_expn(&mut ctx);
1472 let disambiguator = HygieneData::with(|data| {
1473 // If this is the first ExpnData with a given hash, then keep our
1474 // disambiguator at 0 (the default u32 value)
1475 let disambig = data.expn_data_disambiguators.entry(expn_hash).or_default();
1476 let disambiguator = *disambig;
1481 if disambiguator != 0 {
1482 debug!("Set disambiguator for expn_data={:?} expn_hash={:?}", expn_data, expn_hash);
1484 expn_data.disambiguator = disambiguator;
1485 expn_hash = expn_data.hash_expn(&mut ctx);
1487 // Verify that the new disambiguator makes the hash unique
1488 #[cfg(debug_assertions)]
1489 HygieneData::with(|data| {
1491 data.expn_data_disambiguators.get(&expn_hash),
1493 "Hash collision after disambiguator update!",
1498 ExpnHash::new(ctx.def_path_hash(LOCAL_CRATE.as_def_id()).stable_crate_id(), expn_hash)
1501 impl<CTX: HashStableContext> HashStable<CTX> for SyntaxContext {
1502 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1503 const TAG_EXPANSION: u8 = 0;
1504 const TAG_NO_EXPANSION: u8 = 1;
1506 if *self == SyntaxContext::root() {
1507 TAG_NO_EXPANSION.hash_stable(ctx, hasher);
1509 TAG_EXPANSION.hash_stable(ctx, hasher);
1510 let (expn_id, transparency) = self.outer_mark();
1511 expn_id.hash_stable(ctx, hasher);
1512 transparency.hash_stable(ctx, hasher);
1517 impl<CTX: HashStableContext> HashStable<CTX> for ExpnId {
1518 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1519 assert_default_hashing_controls(ctx, "ExpnId");
1520 let hash = if *self == ExpnId::root() {
1521 // Avoid fetching TLS storage for a trivial often-used value.
1527 hash.hash_stable(ctx, hasher);