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
108 // Span hashing can also be disabled without `-Z incremental-ignore-spans`.
109 // This is the case for instance when building a hash for name mangling.
110 // Such configuration must not be used for metadata.
111 HashingControls { hash_spans }
112 if hash_spans == !ctx.unstable_opts_incremental_ignore_spans() => {}
113 other => panic!("Attempted hashing of {msg} with non-default HashingControls: {:?}", other),
117 /// A unique hash value associated to an expansion.
118 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, Encodable, Decodable, HashStable_Generic)]
119 pub struct ExpnHash(Fingerprint);
122 /// Returns the [StableCrateId] identifying the crate this [ExpnHash]
125 pub fn stable_crate_id(self) -> StableCrateId {
126 StableCrateId(self.0.as_value().0)
129 /// Returns the crate-local part of the [ExpnHash].
133 pub fn local_hash(self) -> u64 {
138 pub fn is_root(self) -> bool {
139 self.0 == Fingerprint::ZERO
142 /// Builds a new [ExpnHash] with the given [StableCrateId] and
143 /// `local_hash`, where `local_hash` must be unique within its crate.
144 fn new(stable_crate_id: StableCrateId, local_hash: u64) -> ExpnHash {
145 ExpnHash(Fingerprint::new(stable_crate_id.0, local_hash))
149 /// A property of a macro expansion that determines how identifiers
150 /// produced by that expansion are resolved.
151 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Hash, Debug, Encodable, Decodable)]
152 #[derive(HashStable_Generic)]
153 pub enum Transparency {
154 /// Identifier produced by a transparent expansion is always resolved at call-site.
155 /// Call-site spans in procedural macros, hygiene opt-out in `macro` should use this.
157 /// Identifier produced by a semi-transparent expansion may be resolved
158 /// either at call-site or at definition-site.
159 /// If it's a local variable, label or `$crate` then it's resolved at def-site.
160 /// Otherwise it's resolved at call-site.
161 /// `macro_rules` macros behave like this, built-in macros currently behave like this too,
162 /// but that's an implementation detail.
164 /// Identifier produced by an opaque expansion is always resolved at definition-site.
165 /// Def-site spans in procedural macros, identifiers from `macro` by default use this.
170 /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
171 pub const ROOT: LocalExpnId = LocalExpnId::from_u32(0);
174 pub fn from_raw(idx: ExpnIndex) -> LocalExpnId {
175 LocalExpnId::from_u32(idx.as_u32())
179 pub fn as_raw(self) -> ExpnIndex {
180 ExpnIndex::from_u32(self.as_u32())
183 pub fn fresh_empty() -> LocalExpnId {
184 HygieneData::with(|data| {
185 let expn_id = data.local_expn_data.push(None);
186 let _eid = data.local_expn_hashes.push(ExpnHash(Fingerprint::ZERO));
187 debug_assert_eq!(expn_id, _eid);
192 pub fn fresh(mut expn_data: ExpnData, ctx: impl HashStableContext) -> LocalExpnId {
193 debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
194 let expn_hash = update_disambiguator(&mut expn_data, ctx);
195 HygieneData::with(|data| {
196 let expn_id = data.local_expn_data.push(Some(expn_data));
197 let _eid = data.local_expn_hashes.push(expn_hash);
198 debug_assert_eq!(expn_id, _eid);
199 let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, expn_id.to_expn_id());
200 debug_assert!(_old_id.is_none());
206 pub fn expn_hash(self) -> ExpnHash {
207 HygieneData::with(|data| data.local_expn_hash(self))
211 pub fn expn_data(self) -> ExpnData {
212 HygieneData::with(|data| data.local_expn_data(self).clone())
216 pub fn to_expn_id(self) -> ExpnId {
217 ExpnId { krate: LOCAL_CRATE, local_id: self.as_raw() }
221 pub fn set_expn_data(self, mut expn_data: ExpnData, ctx: impl HashStableContext) {
222 debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
223 let expn_hash = update_disambiguator(&mut expn_data, ctx);
224 HygieneData::with(|data| {
225 let old_expn_data = &mut data.local_expn_data[self];
226 assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
227 *old_expn_data = Some(expn_data);
228 debug_assert_eq!(data.local_expn_hashes[self].0, Fingerprint::ZERO);
229 data.local_expn_hashes[self] = expn_hash;
230 let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, self.to_expn_id());
231 debug_assert!(_old_id.is_none());
236 pub fn is_descendant_of(self, ancestor: LocalExpnId) -> bool {
237 self.to_expn_id().is_descendant_of(ancestor.to_expn_id())
240 /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
241 /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
243 pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
244 self.to_expn_id().outer_expn_is_descendant_of(ctxt)
247 /// Returns span for the macro which originally caused this expansion to happen.
249 /// Stops backtracing at include! boundary.
251 pub fn expansion_cause(self) -> Option<Span> {
252 self.to_expn_id().expansion_cause()
257 pub fn parent(self) -> LocalExpnId {
258 self.expn_data().parent.as_local().unwrap()
263 /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
264 /// Invariant: we do not create any ExpnId with local_id == 0 and krate != 0.
265 pub const fn root() -> ExpnId {
266 ExpnId { krate: LOCAL_CRATE, local_id: ExpnIndex::from_u32(0) }
270 pub fn expn_hash(self) -> ExpnHash {
271 HygieneData::with(|data| data.expn_hash(self))
275 pub fn from_hash(hash: ExpnHash) -> Option<ExpnId> {
276 HygieneData::with(|data| data.expn_hash_to_expn_id.get(&hash).copied())
280 pub fn as_local(self) -> Option<LocalExpnId> {
281 if self.krate == LOCAL_CRATE { Some(LocalExpnId::from_raw(self.local_id)) } else { None }
286 pub fn expect_local(self) -> LocalExpnId {
287 self.as_local().unwrap()
291 pub fn expn_data(self) -> ExpnData {
292 HygieneData::with(|data| data.expn_data(self).clone())
296 pub fn is_descendant_of(self, ancestor: ExpnId) -> bool {
297 // a few "fast path" cases to avoid locking HygieneData
298 if ancestor == ExpnId::root() || ancestor == self {
301 if ancestor.krate != self.krate {
304 HygieneData::with(|data| data.is_descendant_of(self, ancestor))
307 /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
308 /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
309 pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
310 HygieneData::with(|data| data.is_descendant_of(self, data.outer_expn(ctxt)))
313 /// Returns span for the macro which originally caused this expansion to happen.
315 /// Stops backtracing at include! boundary.
316 pub fn expansion_cause(mut self) -> Option<Span> {
317 let mut last_macro = None;
319 let expn_data = self.expn_data();
320 // Stop going up the backtrace once include! is encountered
321 if expn_data.is_root()
322 || expn_data.kind == ExpnKind::Macro(MacroKind::Bang, sym::include)
326 self = expn_data.call_site.ctxt().outer_expn();
327 last_macro = Some(expn_data.call_site);
334 pub struct HygieneData {
335 /// Each expansion should have an associated expansion data, but sometimes there's a delay
336 /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
337 /// first and then resolved later), so we use an `Option` here.
338 local_expn_data: IndexVec<LocalExpnId, Option<ExpnData>>,
339 local_expn_hashes: IndexVec<LocalExpnId, ExpnHash>,
340 /// Data and hash information from external crates. We may eventually want to remove these
341 /// maps, and fetch the information directly from the other crate's metadata like DefIds do.
342 foreign_expn_data: FxHashMap<ExpnId, ExpnData>,
343 foreign_expn_hashes: FxHashMap<ExpnId, ExpnHash>,
344 expn_hash_to_expn_id: UnhashMap<ExpnHash, ExpnId>,
345 syntax_context_data: Vec<SyntaxContextData>,
346 syntax_context_map: FxHashMap<(SyntaxContext, ExpnId, Transparency), SyntaxContext>,
347 /// Maps the `local_hash` of an `ExpnData` to the next disambiguator value.
348 /// This is used by `update_disambiguator` to keep track of which `ExpnData`s
349 /// would have collisions without a disambiguator.
350 /// The keys of this map are always computed with `ExpnData.disambiguator`
352 expn_data_disambiguators: FxHashMap<u64, u32>,
356 pub(crate) fn new(edition: Edition) -> Self {
357 let root_data = ExpnData::default(
361 Some(CRATE_DEF_ID.to_def_id()),
366 local_expn_data: IndexVec::from_elem_n(Some(root_data), 1),
367 local_expn_hashes: IndexVec::from_elem_n(ExpnHash(Fingerprint::ZERO), 1),
368 foreign_expn_data: FxHashMap::default(),
369 foreign_expn_hashes: FxHashMap::default(),
370 expn_hash_to_expn_id: std::iter::once((ExpnHash(Fingerprint::ZERO), ExpnId::root()))
372 syntax_context_data: vec![SyntaxContextData {
373 outer_expn: ExpnId::root(),
374 outer_transparency: Transparency::Opaque,
375 parent: SyntaxContext(0),
376 opaque: SyntaxContext(0),
377 opaque_and_semitransparent: SyntaxContext(0),
378 dollar_crate_name: kw::DollarCrate,
380 syntax_context_map: FxHashMap::default(),
381 expn_data_disambiguators: FxHashMap::default(),
385 pub fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
386 with_session_globals(|session_globals| f(&mut session_globals.hygiene_data.borrow_mut()))
390 fn local_expn_hash(&self, expn_id: LocalExpnId) -> ExpnHash {
391 self.local_expn_hashes[expn_id]
395 fn expn_hash(&self, expn_id: ExpnId) -> ExpnHash {
396 match expn_id.as_local() {
397 Some(expn_id) => self.local_expn_hashes[expn_id],
398 None => self.foreign_expn_hashes[&expn_id],
402 fn local_expn_data(&self, expn_id: LocalExpnId) -> &ExpnData {
403 self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
406 fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
407 if let Some(expn_id) = expn_id.as_local() {
408 self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
410 &self.foreign_expn_data[&expn_id]
414 fn is_descendant_of(&self, mut expn_id: ExpnId, ancestor: ExpnId) -> bool {
415 // a couple "fast path" cases to avoid traversing parents in the loop below
416 if ancestor == ExpnId::root() {
419 if expn_id.krate != ancestor.krate {
423 if expn_id == ancestor {
426 if expn_id == ExpnId::root() {
429 expn_id = self.expn_data(expn_id).parent;
433 fn normalize_to_macros_2_0(&self, ctxt: SyntaxContext) -> SyntaxContext {
434 self.syntax_context_data[ctxt.0 as usize].opaque
437 fn normalize_to_macro_rules(&self, ctxt: SyntaxContext) -> SyntaxContext {
438 self.syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent
441 fn outer_expn(&self, ctxt: SyntaxContext) -> ExpnId {
442 self.syntax_context_data[ctxt.0 as usize].outer_expn
445 fn outer_mark(&self, ctxt: SyntaxContext) -> (ExpnId, Transparency) {
446 let data = &self.syntax_context_data[ctxt.0 as usize];
447 (data.outer_expn, data.outer_transparency)
450 fn parent_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext {
451 self.syntax_context_data[ctxt.0 as usize].parent
454 fn remove_mark(&self, ctxt: &mut SyntaxContext) -> (ExpnId, Transparency) {
455 let outer_mark = self.outer_mark(*ctxt);
456 *ctxt = self.parent_ctxt(*ctxt);
460 fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
461 let mut marks = Vec::new();
462 while ctxt != SyntaxContext::root() {
463 debug!("marks: getting parent of {:?}", ctxt);
464 marks.push(self.outer_mark(ctxt));
465 ctxt = self.parent_ctxt(ctxt);
471 fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span {
472 debug!("walk_chain({:?}, {:?})", span, to);
473 debug!("walk_chain: span ctxt = {:?}", span.ctxt());
474 while span.from_expansion() && span.ctxt() != to {
475 let outer_expn = self.outer_expn(span.ctxt());
476 debug!("walk_chain({:?}): outer_expn={:?}", span, outer_expn);
477 let expn_data = self.expn_data(outer_expn);
478 debug!("walk_chain({:?}): expn_data={:?}", span, expn_data);
479 span = expn_data.call_site;
484 fn adjust(&self, ctxt: &mut SyntaxContext, expn_id: ExpnId) -> Option<ExpnId> {
485 let mut scope = None;
486 while !self.is_descendant_of(expn_id, self.outer_expn(*ctxt)) {
487 scope = Some(self.remove_mark(ctxt).0);
496 transparency: Transparency,
498 assert_ne!(expn_id, ExpnId::root());
499 if transparency == Transparency::Opaque {
500 return self.apply_mark_internal(ctxt, expn_id, transparency);
503 let call_site_ctxt = self.expn_data(expn_id).call_site.ctxt();
504 let mut call_site_ctxt = if transparency == Transparency::SemiTransparent {
505 self.normalize_to_macros_2_0(call_site_ctxt)
507 self.normalize_to_macro_rules(call_site_ctxt)
510 if call_site_ctxt == SyntaxContext::root() {
511 return self.apply_mark_internal(ctxt, expn_id, transparency);
514 // Otherwise, `expn_id` is a macros 1.0 definition and the call site is in a
515 // macros 2.0 expansion, i.e., a macros 1.0 invocation is in a macros 2.0 definition.
517 // In this case, the tokens from the macros 1.0 definition inherit the hygiene
518 // at their invocation. That is, we pretend that the macros 1.0 definition
519 // was defined at its invocation (i.e., inside the macros 2.0 definition)
520 // so that the macros 2.0 definition remains hygienic.
522 // See the example at `test/ui/hygiene/legacy_interaction.rs`.
523 for (expn_id, transparency) in self.marks(ctxt) {
524 call_site_ctxt = self.apply_mark_internal(call_site_ctxt, expn_id, transparency);
526 self.apply_mark_internal(call_site_ctxt, expn_id, transparency)
529 fn apply_mark_internal(
533 transparency: Transparency,
535 let syntax_context_data = &mut self.syntax_context_data;
536 let mut opaque = syntax_context_data[ctxt.0 as usize].opaque;
537 let mut opaque_and_semitransparent =
538 syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent;
540 if transparency >= Transparency::Opaque {
544 .entry((parent, expn_id, transparency))
546 let new_opaque = SyntaxContext(syntax_context_data.len() as u32);
547 syntax_context_data.push(SyntaxContextData {
549 outer_transparency: transparency,
552 opaque_and_semitransparent: new_opaque,
553 dollar_crate_name: kw::DollarCrate,
559 if transparency >= Transparency::SemiTransparent {
560 let parent = opaque_and_semitransparent;
561 opaque_and_semitransparent = *self
563 .entry((parent, expn_id, transparency))
565 let new_opaque_and_semitransparent =
566 SyntaxContext(syntax_context_data.len() as u32);
567 syntax_context_data.push(SyntaxContextData {
569 outer_transparency: transparency,
572 opaque_and_semitransparent: new_opaque_and_semitransparent,
573 dollar_crate_name: kw::DollarCrate,
575 new_opaque_and_semitransparent
580 *self.syntax_context_map.entry((parent, expn_id, transparency)).or_insert_with(|| {
581 let new_opaque_and_semitransparent_and_transparent =
582 SyntaxContext(syntax_context_data.len() as u32);
583 syntax_context_data.push(SyntaxContextData {
585 outer_transparency: transparency,
588 opaque_and_semitransparent,
589 dollar_crate_name: kw::DollarCrate,
591 new_opaque_and_semitransparent_and_transparent
596 pub fn clear_syntax_context_map() {
597 HygieneData::with(|data| data.syntax_context_map = FxHashMap::default());
600 pub fn walk_chain(span: Span, to: SyntaxContext) -> Span {
601 HygieneData::with(|data| data.walk_chain(span, to))
604 pub fn update_dollar_crate_names(mut get_name: impl FnMut(SyntaxContext) -> Symbol) {
605 // The new contexts that need updating are at the end of the list and have `$crate` as a name.
606 let (len, to_update) = HygieneData::with(|data| {
608 data.syntax_context_data.len(),
609 data.syntax_context_data
612 .take_while(|scdata| scdata.dollar_crate_name == kw::DollarCrate)
616 // The callback must be called from outside of the `HygieneData` lock,
617 // since it will try to acquire it too.
618 let range_to_update = len - to_update..len;
620 range_to_update.clone().map(|idx| get_name(SyntaxContext::from_u32(idx as u32))).collect();
621 HygieneData::with(|data| {
622 range_to_update.zip(names).for_each(|(idx, name)| {
623 data.syntax_context_data[idx].dollar_crate_name = name;
628 pub fn debug_hygiene_data(verbose: bool) -> String {
629 HygieneData::with(|data| {
631 format!("{:#?}", data)
633 let mut s = String::from("Expansions:");
634 let mut debug_expn_data = |(id, expn_data): (&ExpnId, &ExpnData)| {
636 "\n{:?}: parent: {:?}, call_site_ctxt: {:?}, def_site_ctxt: {:?}, kind: {:?}",
639 expn_data.call_site.ctxt(),
640 expn_data.def_site.ctxt(),
644 data.local_expn_data.iter_enumerated().for_each(|(id, expn_data)| {
645 let expn_data = expn_data.as_ref().expect("no expansion data for an expansion ID");
646 debug_expn_data((&id.to_expn_id(), expn_data))
649 // Sort the hash map for more reproducible output.
650 // Because of this, it is fine to rely on the unstable iteration order of the map.
651 #[allow(rustc::potential_query_instability)]
652 let mut foreign_expn_data: Vec<_> = data.foreign_expn_data.iter().collect();
653 foreign_expn_data.sort_by_key(|(id, _)| (id.krate, id.local_id));
654 foreign_expn_data.into_iter().for_each(debug_expn_data);
655 s.push_str("\n\nSyntaxContexts:");
656 data.syntax_context_data.iter().enumerate().for_each(|(id, ctxt)| {
658 "\n#{}: parent: {:?}, outer_mark: ({:?}, {:?})",
659 id, ctxt.parent, ctxt.outer_expn, ctxt.outer_transparency,
669 pub const fn root() -> Self {
674 pub(crate) fn as_u32(self) -> u32 {
679 pub(crate) fn from_u32(raw: u32) -> SyntaxContext {
683 /// Extend a syntax context with a given expansion and transparency.
684 pub(crate) fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext {
685 HygieneData::with(|data| data.apply_mark(self, expn_id, transparency))
688 /// Pulls a single mark off of the syntax context. This effectively moves the
689 /// context up one macro definition level. That is, if we have a nested macro
690 /// definition as follows:
692 /// ```ignore (illustrative)
700 /// and we have a SyntaxContext that is referring to something declared by an invocation
701 /// of g (call it g1), calling remove_mark will result in the SyntaxContext for the
702 /// invocation of f that created g1.
703 /// Returns the mark that was removed.
704 pub fn remove_mark(&mut self) -> ExpnId {
705 HygieneData::with(|data| data.remove_mark(self).0)
708 pub fn marks(self) -> Vec<(ExpnId, Transparency)> {
709 HygieneData::with(|data| data.marks(self))
712 /// Adjust this context for resolution in a scope created by the given expansion.
713 /// For example, consider the following three resolutions of `f`:
716 /// #![feature(decl_macro)]
717 /// mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
719 /// macro m($f:ident) {
721 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
722 /// pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
724 /// foo::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
725 /// //^ Since `mod foo` is outside this expansion, `adjust` removes the mark from `f`,
726 /// //| and it resolves to `::foo::f`.
727 /// bar::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
728 /// //^ Since `mod bar` not outside this expansion, `adjust` does not change `f`,
729 /// //| and it resolves to `::bar::f`.
730 /// bar::$f(); // `f`'s `SyntaxContext` is empty.
731 /// //^ Since `mod bar` is not outside this expansion, `adjust` does not change `$f`,
732 /// //| and it resolves to `::bar::$f`.
735 /// This returns the expansion whose definition scope we use to privacy check the resolution,
736 /// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope).
737 pub fn adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
738 HygieneData::with(|data| data.adjust(self, expn_id))
741 /// Like `SyntaxContext::adjust`, but also normalizes `self` to macros 2.0.
742 pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
743 HygieneData::with(|data| {
744 *self = data.normalize_to_macros_2_0(*self);
745 data.adjust(self, expn_id)
749 /// Adjust this context for resolution in a scope created by the given expansion
750 /// via a glob import with the given `SyntaxContext`.
753 /// ```compile_fail,E0425
754 /// #![feature(decl_macro)]
756 /// macro m($i:ident) {
758 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
759 /// pub fn $i() {} // `$i`'s `SyntaxContext` is empty.
762 /// macro n($j:ident) {
764 /// f(); // `f`'s `SyntaxContext` has a mark from `m` and a mark from `n`
765 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::f`.
766 /// $i(); // `$i`'s `SyntaxContext` has a mark from `n`
767 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::$i`.
768 /// $j(); // `$j`'s `SyntaxContext` has a mark from `m`
769 /// //^ This cannot be glob-adjusted, so this is a resolution error.
773 /// This returns `None` if the context cannot be glob-adjusted.
774 /// Otherwise, it returns the scope to use when privacy checking (see `adjust` for details).
775 pub fn glob_adjust(&mut self, expn_id: ExpnId, glob_span: Span) -> Option<Option<ExpnId>> {
776 HygieneData::with(|data| {
777 let mut scope = None;
778 let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
779 while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
780 scope = Some(data.remove_mark(&mut glob_ctxt).0);
781 if data.remove_mark(self).0 != scope.unwrap() {
785 if data.adjust(self, expn_id).is_some() {
792 /// Undo `glob_adjust` if possible:
794 /// ```ignore (illustrative)
795 /// if let Some(privacy_checking_scope) = self.reverse_glob_adjust(expansion, glob_ctxt) {
796 /// assert!(self.glob_adjust(expansion, glob_ctxt) == Some(privacy_checking_scope));
799 pub fn reverse_glob_adjust(
803 ) -> Option<Option<ExpnId>> {
804 HygieneData::with(|data| {
805 if data.adjust(self, expn_id).is_some() {
809 let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
810 let mut marks = Vec::new();
811 while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
812 marks.push(data.remove_mark(&mut glob_ctxt));
815 let scope = marks.last().map(|mark| mark.0);
816 while let Some((expn_id, transparency)) = marks.pop() {
817 *self = data.apply_mark(*self, expn_id, transparency);
823 pub fn hygienic_eq(self, other: SyntaxContext, expn_id: ExpnId) -> bool {
824 HygieneData::with(|data| {
825 let mut self_normalized = data.normalize_to_macros_2_0(self);
826 data.adjust(&mut self_normalized, expn_id);
827 self_normalized == data.normalize_to_macros_2_0(other)
832 pub fn normalize_to_macros_2_0(self) -> SyntaxContext {
833 HygieneData::with(|data| data.normalize_to_macros_2_0(self))
837 pub fn normalize_to_macro_rules(self) -> SyntaxContext {
838 HygieneData::with(|data| data.normalize_to_macro_rules(self))
842 pub fn outer_expn(self) -> ExpnId {
843 HygieneData::with(|data| data.outer_expn(self))
846 /// `ctxt.outer_expn_data()` is equivalent to but faster than
847 /// `ctxt.outer_expn().expn_data()`.
849 pub fn outer_expn_data(self) -> ExpnData {
850 HygieneData::with(|data| data.expn_data(data.outer_expn(self)).clone())
854 pub fn outer_mark(self) -> (ExpnId, Transparency) {
855 HygieneData::with(|data| data.outer_mark(self))
858 pub fn dollar_crate_name(self) -> Symbol {
859 HygieneData::with(|data| data.syntax_context_data[self.0 as usize].dollar_crate_name)
862 pub fn edition(self) -> Edition {
863 HygieneData::with(|data| data.expn_data(data.outer_expn(self)).edition)
867 impl fmt::Debug for SyntaxContext {
868 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
869 write!(f, "#{}", self.0)
874 /// Creates a fresh expansion with given properties.
875 /// Expansions are normally created by macros, but in some cases expansions are created for
876 /// other compiler-generated code to set per-span properties like allowed unstable features.
877 /// The returned span belongs to the created expansion and has the new properties,
878 /// but its location is inherited from the current span.
879 pub fn fresh_expansion(self, expn_id: LocalExpnId) -> Span {
880 HygieneData::with(|data| {
881 self.with_ctxt(data.apply_mark(
882 SyntaxContext::root(),
883 expn_id.to_expn_id(),
884 Transparency::Transparent,
889 /// Reuses the span but adds information like the kind of the desugaring and features that are
890 /// allowed inside this span.
891 pub fn mark_with_reason(
893 allow_internal_unstable: Option<Lrc<[Symbol]>>,
894 reason: DesugaringKind,
896 ctx: impl HashStableContext,
898 let expn_data = ExpnData {
899 allow_internal_unstable,
900 ..ExpnData::default(ExpnKind::Desugaring(reason), self, edition, None, None)
902 let expn_id = LocalExpnId::fresh(expn_data, ctx);
903 self.fresh_expansion(expn_id)
907 /// A subset of properties from both macro definition and macro call available through global data.
908 /// Avoid using this if you have access to the original definition or call structures.
909 #[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
910 pub struct ExpnData {
911 // --- The part unique to each expansion.
912 /// The kind of this expansion - macro or compiler desugaring.
914 /// The expansion that produced this expansion.
916 /// The location of the actual macro invocation or syntax sugar , e.g.
917 /// `let x = foo!();` or `if let Some(y) = x {}`
919 /// This may recursively refer to other macro invocations, e.g., if
920 /// `foo!()` invoked `bar!()` internally, and there was an
921 /// expression inside `bar!`; the call_site of the expression in
922 /// the expansion would point to the `bar!` invocation; that
923 /// call_site span would have its own ExpnData, with the call_site
924 /// pointing to the `foo!` invocation.
926 /// Used to force two `ExpnData`s to have different `Fingerprint`s.
927 /// Due to macro expansion, it's possible to end up with two `ExpnId`s
928 /// that have identical `ExpnData`s. This violates the contract of `HashStable`
929 /// - the two `ExpnId`s are not equal, but their `Fingerprint`s are equal
930 /// (since the numerical `ExpnId` value is not considered by the `HashStable`
933 /// The `disambiguator` field is set by `update_disambiguator` when two distinct
934 /// `ExpnId`s would end up with the same `Fingerprint`. Since `ExpnData` includes
935 /// a `krate` field, this value only needs to be unique within a single crate.
938 // --- The part specific to the macro/desugaring definition.
939 // --- It may be reasonable to share this part between expansions with the same definition,
940 // --- but such sharing is known to bring some minor inconveniences without also bringing
941 // --- noticeable perf improvements (PR #62898).
942 /// The span of the macro definition (possibly dummy).
943 /// This span serves only informational purpose and is not used for resolution.
945 /// List of `#[unstable]`/feature-gated features that the macro is allowed to use
946 /// internally without forcing the whole crate to opt-in
948 pub allow_internal_unstable: Option<Lrc<[Symbol]>>,
949 /// Edition of the crate in which the macro is defined.
950 pub edition: Edition,
951 /// The `DefId` of the macro being invoked,
952 /// if this `ExpnData` corresponds to a macro invocation
953 pub macro_def_id: Option<DefId>,
954 /// The normal module (`mod`) in which the expanded macro was defined.
955 pub parent_module: Option<DefId>,
956 /// Suppresses the `unsafe_code` lint for code produced by this macro.
957 pub allow_internal_unsafe: bool,
958 /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`) for this macro.
959 pub local_inner_macros: bool,
960 /// Should debuginfo for the macro be collapsed to the outermost expansion site (in other
961 /// words, was the macro definition annotated with `#[collapse_debuginfo]`)?
962 pub collapse_debuginfo: bool,
965 impl !PartialEq for ExpnData {}
966 impl !Hash for ExpnData {}
974 allow_internal_unstable: Option<Lrc<[Symbol]>>,
976 macro_def_id: Option<DefId>,
977 parent_module: Option<DefId>,
978 allow_internal_unsafe: bool,
979 local_inner_macros: bool,
980 collapse_debuginfo: bool,
987 allow_internal_unstable,
992 allow_internal_unsafe,
998 /// Constructs expansion data with default properties.
1003 macro_def_id: Option<DefId>,
1004 parent_module: Option<DefId>,
1008 parent: ExpnId::root(),
1011 allow_internal_unstable: None,
1016 allow_internal_unsafe: false,
1017 local_inner_macros: false,
1018 collapse_debuginfo: false,
1022 pub fn allow_unstable(
1026 allow_internal_unstable: Lrc<[Symbol]>,
1027 macro_def_id: Option<DefId>,
1028 parent_module: Option<DefId>,
1031 allow_internal_unstable: Some(allow_internal_unstable),
1032 ..ExpnData::default(kind, call_site, edition, macro_def_id, parent_module)
1037 pub fn is_root(&self) -> bool {
1038 matches!(self.kind, ExpnKind::Root)
1042 fn hash_expn(&self, ctx: &mut impl HashStableContext) -> u64 {
1043 let mut hasher = StableHasher::new();
1044 self.hash_stable(ctx, &mut hasher);
1050 #[derive(Clone, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
1052 /// No expansion, aka root expansion. Only `ExpnId::root()` has this kind.
1054 /// Expansion produced by a macro.
1055 Macro(MacroKind, Symbol),
1056 /// Transform done by the compiler on the AST.
1058 /// Desugaring done by the compiler during HIR lowering.
1059 Desugaring(DesugaringKind),
1065 pub fn descr(&self) -> String {
1067 ExpnKind::Root => kw::PathRoot.to_string(),
1068 ExpnKind::Macro(macro_kind, name) => match macro_kind {
1069 MacroKind::Bang => format!("{}!", name),
1070 MacroKind::Attr => format!("#[{}]", name),
1071 MacroKind::Derive => format!("#[derive({})]", name),
1073 ExpnKind::AstPass(kind) => kind.descr().to_string(),
1074 ExpnKind::Desugaring(kind) => format!("desugaring of {}", kind.descr()),
1075 ExpnKind::Inlined => "inlined source".to_string(),
1080 /// The kind of macro invocation or definition.
1081 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
1082 #[derive(HashStable_Generic)]
1083 pub enum MacroKind {
1084 /// A bang macro `foo!()`.
1086 /// An attribute macro `#[foo]`.
1088 /// A derive macro `#[derive(Foo)]`
1093 pub fn descr(self) -> &'static str {
1095 MacroKind::Bang => "macro",
1096 MacroKind::Attr => "attribute macro",
1097 MacroKind::Derive => "derive macro",
1101 pub fn descr_expected(self) -> &'static str {
1103 MacroKind::Attr => "attribute",
1108 pub fn article(self) -> &'static str {
1110 MacroKind::Attr => "an",
1116 /// The kind of AST transform.
1117 #[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
1125 pub fn descr(self) -> &'static str {
1127 AstPass::StdImports => "standard library imports",
1128 AstPass::TestHarness => "test harness",
1129 AstPass::ProcMacroHarness => "proc macro harness",
1134 /// The kind of compiler desugaring.
1135 #[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
1136 pub enum DesugaringKind {
1137 /// We desugar `if c { i } else { e }` to `match $ExprKind::Use(c) { true => i, _ => e }`.
1138 /// However, we do not want to blame `c` for unreachability but rather say that `i`
1139 /// is unreachable. This desugaring kind allows us to avoid blaming `c`.
1140 /// This also applies to `while` loops.
1145 /// Desugaring of an `impl Trait` in return type position
1146 /// to an `type Foo = impl Trait;` and replacing the
1147 /// `impl Trait` with `Foo`.
1155 impl DesugaringKind {
1156 /// The description wording should combine well with "desugaring of {}".
1157 pub fn descr(self) -> &'static str {
1159 DesugaringKind::CondTemporary => "`if` or `while` condition",
1160 DesugaringKind::Async => "`async` block or function",
1161 DesugaringKind::Await => "`await` expression",
1162 DesugaringKind::QuestionMark => "operator `?`",
1163 DesugaringKind::TryBlock => "`try` block",
1164 DesugaringKind::YeetExpr => "`do yeet` expression",
1165 DesugaringKind::OpaqueTy => "`impl Trait`",
1166 DesugaringKind::ForLoop => "`for` loop",
1167 DesugaringKind::WhileLoop => "`while` loop",
1173 pub struct HygieneEncodeContext {
1174 /// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
1175 /// This is `None` after we finish encoding `SyntaxContexts`, to ensure
1176 /// that we don't accidentally try to encode any more `SyntaxContexts`
1177 serialized_ctxts: Lock<FxHashSet<SyntaxContext>>,
1178 /// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
1179 /// in the most recent 'round' of serializing. Serializing `SyntaxContextData`
1180 /// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
1181 /// until we reach a fixed point.
1182 latest_ctxts: Lock<FxHashSet<SyntaxContext>>,
1184 serialized_expns: Lock<FxHashSet<ExpnId>>,
1186 latest_expns: Lock<FxHashSet<ExpnId>>,
1189 impl HygieneEncodeContext {
1190 /// Record the fact that we need to serialize the corresponding `ExpnData`.
1191 pub fn schedule_expn_data_for_encoding(&self, expn: ExpnId) {
1192 if !self.serialized_expns.lock().contains(&expn) {
1193 self.latest_expns.lock().insert(expn);
1200 mut encode_ctxt: impl FnMut(&mut T, u32, &SyntaxContextData),
1201 mut encode_expn: impl FnMut(&mut T, ExpnId, &ExpnData, ExpnHash),
1203 // When we serialize a `SyntaxContextData`, we may end up serializing
1204 // a `SyntaxContext` that we haven't seen before
1205 while !self.latest_ctxts.lock().is_empty() || !self.latest_expns.lock().is_empty() {
1207 "encode_hygiene: Serializing a round of {:?} SyntaxContextDatas: {:?}",
1208 self.latest_ctxts.lock().len(),
1212 // Consume the current round of SyntaxContexts.
1213 // Drop the lock() temporary early
1214 let latest_ctxts = { std::mem::take(&mut *self.latest_ctxts.lock()) };
1216 // It's fine to iterate over a HashMap, because the serialization
1217 // of the table that we insert data into doesn't depend on insertion
1219 #[allow(rustc::potential_query_instability)]
1220 for_all_ctxts_in(latest_ctxts.into_iter(), |index, ctxt, data| {
1221 if self.serialized_ctxts.lock().insert(ctxt) {
1222 encode_ctxt(encoder, index, data);
1226 let latest_expns = { std::mem::take(&mut *self.latest_expns.lock()) };
1228 // Same as above, this is fine as we are inserting into a order-independent hashset
1229 #[allow(rustc::potential_query_instability)]
1230 for_all_expns_in(latest_expns.into_iter(), |expn, data, hash| {
1231 if self.serialized_expns.lock().insert(expn) {
1232 encode_expn(encoder, expn, data, hash);
1236 debug!("encode_hygiene: Done serializing SyntaxContextData");
1241 /// Additional information used to assist in decoding hygiene data
1242 pub struct HygieneDecodeContext {
1243 // Maps serialized `SyntaxContext` ids to a `SyntaxContext` in the current
1244 // global `HygieneData`. When we deserialize a `SyntaxContext`, we need to create
1245 // a new id in the global `HygieneData`. This map tracks the ID we end up picking,
1246 // so that multiple occurrences of the same serialized id are decoded to the same
1248 remapped_ctxts: Lock<Vec<Option<SyntaxContext>>>,
1251 /// Register an expansion which has been decoded from the on-disk-cache for the local crate.
1252 pub fn register_local_expn_id(data: ExpnData, hash: ExpnHash) -> ExpnId {
1253 HygieneData::with(|hygiene_data| {
1254 let expn_id = hygiene_data.local_expn_data.next_index();
1255 hygiene_data.local_expn_data.push(Some(data));
1256 let _eid = hygiene_data.local_expn_hashes.push(hash);
1257 debug_assert_eq!(expn_id, _eid);
1259 let expn_id = expn_id.to_expn_id();
1261 let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
1262 debug_assert!(_old_id.is_none());
1267 /// Register an expansion which has been decoded from the metadata of a foreign crate.
1268 pub fn register_expn_id(
1270 local_id: ExpnIndex,
1274 debug_assert!(data.parent == ExpnId::root() || krate == data.parent.krate);
1275 let expn_id = ExpnId { krate, local_id };
1276 HygieneData::with(|hygiene_data| {
1277 let _old_data = hygiene_data.foreign_expn_data.insert(expn_id, data);
1278 debug_assert!(_old_data.is_none());
1279 let _old_hash = hygiene_data.foreign_expn_hashes.insert(expn_id, hash);
1280 debug_assert!(_old_hash.is_none());
1281 let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
1282 debug_assert!(_old_id.is_none());
1287 /// Decode an expansion from the metadata of a foreign crate.
1288 pub fn decode_expn_id(
1291 decode_data: impl FnOnce(ExpnId) -> (ExpnData, ExpnHash),
1294 debug!("decode_expn_id: deserialized root");
1295 return ExpnId::root();
1298 let index = ExpnIndex::from_u32(index);
1300 // This function is used to decode metadata, so it cannot decode information about LOCAL_CRATE.
1301 debug_assert_ne!(krate, LOCAL_CRATE);
1302 let expn_id = ExpnId { krate, local_id: index };
1304 // Fast path if the expansion has already been decoded.
1305 if HygieneData::with(|hygiene_data| hygiene_data.foreign_expn_data.contains_key(&expn_id)) {
1309 // Don't decode the data inside `HygieneData::with`, since we need to recursively decode
1311 let (expn_data, hash) = decode_data(expn_id);
1313 register_expn_id(krate, index, expn_data, hash)
1316 // Decodes `SyntaxContext`, using the provided `HygieneDecodeContext`
1317 // to track which `SyntaxContext`s we have already decoded.
1318 // The provided closure will be invoked to deserialize a `SyntaxContextData`
1319 // if we haven't already seen the id of the `SyntaxContext` we are deserializing.
1320 pub fn decode_syntax_context<D: Decoder, F: FnOnce(&mut D, u32) -> SyntaxContextData>(
1322 context: &HygieneDecodeContext,
1324 ) -> SyntaxContext {
1325 let raw_id: u32 = Decodable::decode(d);
1327 debug!("decode_syntax_context: deserialized root");
1328 // The root is special
1329 return SyntaxContext::root();
1332 let outer_ctxts = &context.remapped_ctxts;
1334 // Ensure that the lock() temporary is dropped early
1336 if let Some(ctxt) = outer_ctxts.lock().get(raw_id as usize).copied().flatten() {
1341 // Allocate and store SyntaxContext id *before* calling the decoder function,
1342 // as the SyntaxContextData may reference itself.
1343 let new_ctxt = HygieneData::with(|hygiene_data| {
1344 let new_ctxt = SyntaxContext(hygiene_data.syntax_context_data.len() as u32);
1345 // Push a dummy SyntaxContextData to ensure that nobody else can get the
1346 // same ID as us. This will be overwritten after call `decode_Data`
1347 hygiene_data.syntax_context_data.push(SyntaxContextData {
1348 outer_expn: ExpnId::root(),
1349 outer_transparency: Transparency::Transparent,
1350 parent: SyntaxContext::root(),
1351 opaque: SyntaxContext::root(),
1352 opaque_and_semitransparent: SyntaxContext::root(),
1353 dollar_crate_name: kw::Empty,
1355 let mut ctxts = outer_ctxts.lock();
1356 let new_len = raw_id as usize + 1;
1357 if ctxts.len() < new_len {
1358 ctxts.resize(new_len, None);
1360 ctxts[raw_id as usize] = Some(new_ctxt);
1365 // Don't try to decode data while holding the lock, since we need to
1366 // be able to recursively decode a SyntaxContext
1367 let mut ctxt_data = decode_data(d, raw_id);
1368 // Reset `dollar_crate_name` so that it will be updated by `update_dollar_crate_names`
1369 // We don't care what the encoding crate set this to - we want to resolve it
1370 // from the perspective of the current compilation session
1371 ctxt_data.dollar_crate_name = kw::DollarCrate;
1373 // Overwrite the dummy data with our decoded SyntaxContextData
1374 HygieneData::with(|hygiene_data| {
1375 let dummy = std::mem::replace(
1376 &mut hygiene_data.syntax_context_data[new_ctxt.as_u32() as usize],
1379 // Make sure nothing weird happening while `decode_data` was running
1380 assert_eq!(dummy.dollar_crate_name, kw::Empty);
1386 fn for_all_ctxts_in<F: FnMut(u32, SyntaxContext, &SyntaxContextData)>(
1387 ctxts: impl Iterator<Item = SyntaxContext>,
1390 let all_data: Vec<_> = HygieneData::with(|data| {
1391 ctxts.map(|ctxt| (ctxt, data.syntax_context_data[ctxt.0 as usize].clone())).collect()
1393 for (ctxt, data) in all_data.into_iter() {
1394 f(ctxt.0, ctxt, &data);
1398 fn for_all_expns_in(
1399 expns: impl Iterator<Item = ExpnId>,
1400 mut f: impl FnMut(ExpnId, &ExpnData, ExpnHash),
1402 let all_data: Vec<_> = HygieneData::with(|data| {
1403 expns.map(|expn| (expn, data.expn_data(expn).clone(), data.expn_hash(expn))).collect()
1405 for (expn, data, hash) in all_data.into_iter() {
1406 f(expn, &data, hash);
1410 impl<E: Encoder> Encodable<E> for LocalExpnId {
1411 fn encode(&self, e: &mut E) {
1412 self.to_expn_id().encode(e);
1416 impl<E: Encoder> Encodable<E> for ExpnId {
1417 default fn encode(&self, _: &mut E) {
1418 panic!("cannot encode `ExpnId` with `{}`", std::any::type_name::<E>());
1422 impl<D: Decoder> Decodable<D> for LocalExpnId {
1423 fn decode(d: &mut D) -> Self {
1424 ExpnId::expect_local(ExpnId::decode(d))
1428 impl<D: Decoder> Decodable<D> for ExpnId {
1429 default fn decode(_: &mut D) -> Self {
1430 panic!("cannot decode `ExpnId` with `{}`", std::any::type_name::<D>());
1434 pub fn raw_encode_syntax_context<E: Encoder>(
1435 ctxt: SyntaxContext,
1436 context: &HygieneEncodeContext,
1439 if !context.serialized_ctxts.lock().contains(&ctxt) {
1440 context.latest_ctxts.lock().insert(ctxt);
1445 impl<E: Encoder> Encodable<E> for SyntaxContext {
1446 default fn encode(&self, _: &mut E) {
1447 panic!("cannot encode `SyntaxContext` with `{}`", std::any::type_name::<E>());
1451 impl<D: Decoder> Decodable<D> for SyntaxContext {
1452 default fn decode(_: &mut D) -> Self {
1453 panic!("cannot decode `SyntaxContext` with `{}`", std::any::type_name::<D>());
1457 /// Updates the `disambiguator` field of the corresponding `ExpnData`
1458 /// such that the `Fingerprint` of the `ExpnData` does not collide with
1459 /// any other `ExpnIds`.
1461 /// This method is called only when an `ExpnData` is first associated
1462 /// with an `ExpnId` (when the `ExpnId` is initially constructed, or via
1463 /// `set_expn_data`). It is *not* called for foreign `ExpnId`s deserialized
1464 /// from another crate's metadata - since `ExpnHash` includes the stable crate id,
1465 /// collisions are only possible between `ExpnId`s within the same crate.
1466 fn update_disambiguator(expn_data: &mut ExpnData, mut ctx: impl HashStableContext) -> ExpnHash {
1467 // This disambiguator should not have been set yet.
1469 expn_data.disambiguator, 0,
1470 "Already set disambiguator for ExpnData: {:?}",
1473 assert_default_hashing_controls(&ctx, "ExpnData (disambiguator)");
1474 let mut expn_hash = expn_data.hash_expn(&mut ctx);
1476 let disambiguator = HygieneData::with(|data| {
1477 // If this is the first ExpnData with a given hash, then keep our
1478 // disambiguator at 0 (the default u32 value)
1479 let disambig = data.expn_data_disambiguators.entry(expn_hash).or_default();
1480 let disambiguator = *disambig;
1485 if disambiguator != 0 {
1486 debug!("Set disambiguator for expn_data={:?} expn_hash={:?}", expn_data, expn_hash);
1488 expn_data.disambiguator = disambiguator;
1489 expn_hash = expn_data.hash_expn(&mut ctx);
1491 // Verify that the new disambiguator makes the hash unique
1492 #[cfg(debug_assertions)]
1493 HygieneData::with(|data| {
1495 data.expn_data_disambiguators.get(&expn_hash),
1497 "Hash collision after disambiguator update!",
1502 ExpnHash::new(ctx.def_path_hash(LOCAL_CRATE.as_def_id()).stable_crate_id(), expn_hash)
1505 impl<CTX: HashStableContext> HashStable<CTX> for SyntaxContext {
1506 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1507 const TAG_EXPANSION: u8 = 0;
1508 const TAG_NO_EXPANSION: u8 = 1;
1510 if *self == SyntaxContext::root() {
1511 TAG_NO_EXPANSION.hash_stable(ctx, hasher);
1513 TAG_EXPANSION.hash_stable(ctx, hasher);
1514 let (expn_id, transparency) = self.outer_mark();
1515 expn_id.hash_stable(ctx, hasher);
1516 transparency.hash_stable(ctx, hasher);
1521 impl<CTX: HashStableContext> HashStable<CTX> for ExpnId {
1522 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1523 assert_default_hashing_controls(ctx, "ExpnId");
1524 let hash = if *self == ExpnId::root() {
1525 // Avoid fetching TLS storage for a trivial often-used value.
1531 hash.hash_stable(ctx, hasher);