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)
319 || expn_data.kind == ExpnKind::Inlined
323 self = expn_data.call_site.ctxt().outer_expn();
324 last_macro = Some(expn_data.call_site);
331 pub struct HygieneData {
332 /// Each expansion should have an associated expansion data, but sometimes there's a delay
333 /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
334 /// first and then resolved later), so we use an `Option` here.
335 local_expn_data: IndexVec<LocalExpnId, Option<ExpnData>>,
336 local_expn_hashes: IndexVec<LocalExpnId, ExpnHash>,
337 /// Data and hash information from external crates. We may eventually want to remove these
338 /// maps, and fetch the information directly from the other crate's metadata like DefIds do.
339 foreign_expn_data: FxHashMap<ExpnId, ExpnData>,
340 foreign_expn_hashes: FxHashMap<ExpnId, ExpnHash>,
341 expn_hash_to_expn_id: UnhashMap<ExpnHash, ExpnId>,
342 syntax_context_data: Vec<SyntaxContextData>,
343 syntax_context_map: FxHashMap<(SyntaxContext, ExpnId, Transparency), SyntaxContext>,
344 /// Maps the `local_hash` of an `ExpnData` to the next disambiguator value.
345 /// This is used by `update_disambiguator` to keep track of which `ExpnData`s
346 /// would have collisions without a disambiguator.
347 /// The keys of this map are always computed with `ExpnData.disambiguator`
349 expn_data_disambiguators: FxHashMap<u64, u32>,
353 pub(crate) fn new(edition: Edition) -> Self {
354 let root_data = ExpnData::default(
358 Some(CRATE_DEF_ID.to_def_id()),
363 local_expn_data: IndexVec::from_elem_n(Some(root_data), 1),
364 local_expn_hashes: IndexVec::from_elem_n(ExpnHash(Fingerprint::ZERO), 1),
365 foreign_expn_data: FxHashMap::default(),
366 foreign_expn_hashes: FxHashMap::default(),
367 expn_hash_to_expn_id: std::iter::once((ExpnHash(Fingerprint::ZERO), ExpnId::root()))
369 syntax_context_data: vec![SyntaxContextData {
370 outer_expn: ExpnId::root(),
371 outer_transparency: Transparency::Opaque,
372 parent: SyntaxContext(0),
373 opaque: SyntaxContext(0),
374 opaque_and_semitransparent: SyntaxContext(0),
375 dollar_crate_name: kw::DollarCrate,
377 syntax_context_map: FxHashMap::default(),
378 expn_data_disambiguators: FxHashMap::default(),
382 pub fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
383 with_session_globals(|session_globals| f(&mut session_globals.hygiene_data.borrow_mut()))
387 fn local_expn_hash(&self, expn_id: LocalExpnId) -> ExpnHash {
388 self.local_expn_hashes[expn_id]
392 fn expn_hash(&self, expn_id: ExpnId) -> ExpnHash {
393 match expn_id.as_local() {
394 Some(expn_id) => self.local_expn_hashes[expn_id],
395 None => self.foreign_expn_hashes[&expn_id],
399 fn local_expn_data(&self, expn_id: LocalExpnId) -> &ExpnData {
400 self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
403 fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
404 if let Some(expn_id) = expn_id.as_local() {
405 self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
407 &self.foreign_expn_data[&expn_id]
411 fn is_descendant_of(&self, mut expn_id: ExpnId, ancestor: ExpnId) -> bool {
412 // a couple "fast path" cases to avoid traversing parents in the loop below
413 if ancestor == ExpnId::root() {
416 if expn_id.krate != ancestor.krate {
420 if expn_id == ancestor {
423 if expn_id == ExpnId::root() {
426 expn_id = self.expn_data(expn_id).parent;
430 fn normalize_to_macros_2_0(&self, ctxt: SyntaxContext) -> SyntaxContext {
431 self.syntax_context_data[ctxt.0 as usize].opaque
434 fn normalize_to_macro_rules(&self, ctxt: SyntaxContext) -> SyntaxContext {
435 self.syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent
438 fn outer_expn(&self, ctxt: SyntaxContext) -> ExpnId {
439 self.syntax_context_data[ctxt.0 as usize].outer_expn
442 fn outer_mark(&self, ctxt: SyntaxContext) -> (ExpnId, Transparency) {
443 let data = &self.syntax_context_data[ctxt.0 as usize];
444 (data.outer_expn, data.outer_transparency)
447 fn parent_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext {
448 self.syntax_context_data[ctxt.0 as usize].parent
451 fn remove_mark(&self, ctxt: &mut SyntaxContext) -> (ExpnId, Transparency) {
452 let outer_mark = self.outer_mark(*ctxt);
453 *ctxt = self.parent_ctxt(*ctxt);
457 fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
458 let mut marks = Vec::new();
459 while ctxt != SyntaxContext::root() {
460 debug!("marks: getting parent of {:?}", ctxt);
461 marks.push(self.outer_mark(ctxt));
462 ctxt = self.parent_ctxt(ctxt);
468 fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span {
469 debug!("walk_chain({:?}, {:?})", span, to);
470 debug!("walk_chain: span ctxt = {:?}", span.ctxt());
471 while span.from_expansion() && span.ctxt() != to {
472 let outer_expn = self.outer_expn(span.ctxt());
473 debug!("walk_chain({:?}): outer_expn={:?}", span, outer_expn);
474 let expn_data = self.expn_data(outer_expn);
475 debug!("walk_chain({:?}): expn_data={:?}", span, expn_data);
476 span = expn_data.call_site;
481 fn adjust(&self, ctxt: &mut SyntaxContext, expn_id: ExpnId) -> Option<ExpnId> {
482 let mut scope = None;
483 while !self.is_descendant_of(expn_id, self.outer_expn(*ctxt)) {
484 scope = Some(self.remove_mark(ctxt).0);
493 transparency: Transparency,
495 assert_ne!(expn_id, ExpnId::root());
496 if transparency == Transparency::Opaque {
497 return self.apply_mark_internal(ctxt, expn_id, transparency);
500 let call_site_ctxt = self.expn_data(expn_id).call_site.ctxt();
501 let mut call_site_ctxt = if transparency == Transparency::SemiTransparent {
502 self.normalize_to_macros_2_0(call_site_ctxt)
504 self.normalize_to_macro_rules(call_site_ctxt)
507 if call_site_ctxt == SyntaxContext::root() {
508 return self.apply_mark_internal(ctxt, expn_id, transparency);
511 // Otherwise, `expn_id` is a macros 1.0 definition and the call site is in a
512 // macros 2.0 expansion, i.e., a macros 1.0 invocation is in a macros 2.0 definition.
514 // In this case, the tokens from the macros 1.0 definition inherit the hygiene
515 // at their invocation. That is, we pretend that the macros 1.0 definition
516 // was defined at its invocation (i.e., inside the macros 2.0 definition)
517 // so that the macros 2.0 definition remains hygienic.
519 // See the example at `test/ui/hygiene/legacy_interaction.rs`.
520 for (expn_id, transparency) in self.marks(ctxt) {
521 call_site_ctxt = self.apply_mark_internal(call_site_ctxt, expn_id, transparency);
523 self.apply_mark_internal(call_site_ctxt, expn_id, transparency)
526 fn apply_mark_internal(
530 transparency: Transparency,
532 let syntax_context_data = &mut self.syntax_context_data;
533 let mut opaque = syntax_context_data[ctxt.0 as usize].opaque;
534 let mut opaque_and_semitransparent =
535 syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent;
537 if transparency >= Transparency::Opaque {
541 .entry((parent, expn_id, transparency))
543 let new_opaque = SyntaxContext(syntax_context_data.len() as u32);
544 syntax_context_data.push(SyntaxContextData {
546 outer_transparency: transparency,
549 opaque_and_semitransparent: new_opaque,
550 dollar_crate_name: kw::DollarCrate,
556 if transparency >= Transparency::SemiTransparent {
557 let parent = opaque_and_semitransparent;
558 opaque_and_semitransparent = *self
560 .entry((parent, expn_id, transparency))
562 let new_opaque_and_semitransparent =
563 SyntaxContext(syntax_context_data.len() as u32);
564 syntax_context_data.push(SyntaxContextData {
566 outer_transparency: transparency,
569 opaque_and_semitransparent: new_opaque_and_semitransparent,
570 dollar_crate_name: kw::DollarCrate,
572 new_opaque_and_semitransparent
577 *self.syntax_context_map.entry((parent, expn_id, transparency)).or_insert_with(|| {
578 let new_opaque_and_semitransparent_and_transparent =
579 SyntaxContext(syntax_context_data.len() as u32);
580 syntax_context_data.push(SyntaxContextData {
582 outer_transparency: transparency,
585 opaque_and_semitransparent,
586 dollar_crate_name: kw::DollarCrate,
588 new_opaque_and_semitransparent_and_transparent
593 pub fn clear_syntax_context_map() {
594 HygieneData::with(|data| data.syntax_context_map = FxHashMap::default());
597 pub fn walk_chain(span: Span, to: SyntaxContext) -> Span {
598 HygieneData::with(|data| data.walk_chain(span, to))
601 pub fn update_dollar_crate_names(mut get_name: impl FnMut(SyntaxContext) -> Symbol) {
602 // The new contexts that need updating are at the end of the list and have `$crate` as a name.
603 let (len, to_update) = HygieneData::with(|data| {
605 data.syntax_context_data.len(),
606 data.syntax_context_data
609 .take_while(|scdata| scdata.dollar_crate_name == kw::DollarCrate)
613 // The callback must be called from outside of the `HygieneData` lock,
614 // since it will try to acquire it too.
615 let range_to_update = len - to_update..len;
617 range_to_update.clone().map(|idx| get_name(SyntaxContext::from_u32(idx as u32))).collect();
618 HygieneData::with(|data| {
619 range_to_update.zip(names).for_each(|(idx, name)| {
620 data.syntax_context_data[idx].dollar_crate_name = name;
625 pub fn debug_hygiene_data(verbose: bool) -> String {
626 HygieneData::with(|data| {
628 format!("{:#?}", data)
630 let mut s = String::from("Expansions:");
631 let mut debug_expn_data = |(id, expn_data): (&ExpnId, &ExpnData)| {
633 "\n{:?}: parent: {:?}, call_site_ctxt: {:?}, def_site_ctxt: {:?}, kind: {:?}",
636 expn_data.call_site.ctxt(),
637 expn_data.def_site.ctxt(),
641 data.local_expn_data.iter_enumerated().for_each(|(id, expn_data)| {
642 let expn_data = expn_data.as_ref().expect("no expansion data for an expansion ID");
643 debug_expn_data((&id.to_expn_id(), expn_data))
646 // Sort the hash map for more reproducible output.
647 // Because of this, it is fine to rely on the unstable iteration order of the map.
648 #[allow(rustc::potential_query_instability)]
649 let mut foreign_expn_data: Vec<_> = data.foreign_expn_data.iter().collect();
650 foreign_expn_data.sort_by_key(|(id, _)| (id.krate, id.local_id));
651 foreign_expn_data.into_iter().for_each(debug_expn_data);
652 s.push_str("\n\nSyntaxContexts:");
653 data.syntax_context_data.iter().enumerate().for_each(|(id, ctxt)| {
655 "\n#{}: parent: {:?}, outer_mark: ({:?}, {:?})",
656 id, ctxt.parent, ctxt.outer_expn, ctxt.outer_transparency,
666 pub const fn root() -> Self {
671 pub(crate) fn as_u32(self) -> u32 {
676 pub(crate) fn from_u32(raw: u32) -> SyntaxContext {
680 /// Extend a syntax context with a given expansion and transparency.
681 pub(crate) fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext {
682 HygieneData::with(|data| data.apply_mark(self, expn_id, transparency))
685 /// Pulls a single mark off of the syntax context. This effectively moves the
686 /// context up one macro definition level. That is, if we have a nested macro
687 /// definition as follows:
689 /// ```ignore (illustrative)
697 /// and we have a SyntaxContext that is referring to something declared by an invocation
698 /// of g (call it g1), calling remove_mark will result in the SyntaxContext for the
699 /// invocation of f that created g1.
700 /// Returns the mark that was removed.
701 pub fn remove_mark(&mut self) -> ExpnId {
702 HygieneData::with(|data| data.remove_mark(self).0)
705 pub fn marks(self) -> Vec<(ExpnId, Transparency)> {
706 HygieneData::with(|data| data.marks(self))
709 /// Adjust this context for resolution in a scope created by the given expansion.
710 /// For example, consider the following three resolutions of `f`:
713 /// #![feature(decl_macro)]
714 /// mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
716 /// macro m($f:ident) {
718 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
719 /// pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
721 /// foo::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
722 /// //^ Since `mod foo` is outside this expansion, `adjust` removes the mark from `f`,
723 /// //| and it resolves to `::foo::f`.
724 /// bar::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
725 /// //^ Since `mod bar` not outside this expansion, `adjust` does not change `f`,
726 /// //| and it resolves to `::bar::f`.
727 /// bar::$f(); // `f`'s `SyntaxContext` is empty.
728 /// //^ Since `mod bar` is not outside this expansion, `adjust` does not change `$f`,
729 /// //| and it resolves to `::bar::$f`.
732 /// This returns the expansion whose definition scope we use to privacy check the resolution,
733 /// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope).
734 pub fn adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
735 HygieneData::with(|data| data.adjust(self, expn_id))
738 /// Like `SyntaxContext::adjust`, but also normalizes `self` to macros 2.0.
739 pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
740 HygieneData::with(|data| {
741 *self = data.normalize_to_macros_2_0(*self);
742 data.adjust(self, expn_id)
746 /// Adjust this context for resolution in a scope created by the given expansion
747 /// via a glob import with the given `SyntaxContext`.
750 /// ```compile_fail,E0425
751 /// #![feature(decl_macro)]
753 /// macro m($i:ident) {
755 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
756 /// pub fn $i() {} // `$i`'s `SyntaxContext` is empty.
759 /// macro n($j:ident) {
761 /// f(); // `f`'s `SyntaxContext` has a mark from `m` and a mark from `n`
762 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::f`.
763 /// $i(); // `$i`'s `SyntaxContext` has a mark from `n`
764 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::$i`.
765 /// $j(); // `$j`'s `SyntaxContext` has a mark from `m`
766 /// //^ This cannot be glob-adjusted, so this is a resolution error.
770 /// This returns `None` if the context cannot be glob-adjusted.
771 /// Otherwise, it returns the scope to use when privacy checking (see `adjust` for details).
772 pub fn glob_adjust(&mut self, expn_id: ExpnId, glob_span: Span) -> Option<Option<ExpnId>> {
773 HygieneData::with(|data| {
774 let mut scope = None;
775 let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
776 while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
777 scope = Some(data.remove_mark(&mut glob_ctxt).0);
778 if data.remove_mark(self).0 != scope.unwrap() {
782 if data.adjust(self, expn_id).is_some() {
789 /// Undo `glob_adjust` if possible:
791 /// ```ignore (illustrative)
792 /// if let Some(privacy_checking_scope) = self.reverse_glob_adjust(expansion, glob_ctxt) {
793 /// assert!(self.glob_adjust(expansion, glob_ctxt) == Some(privacy_checking_scope));
796 pub fn reverse_glob_adjust(
800 ) -> Option<Option<ExpnId>> {
801 HygieneData::with(|data| {
802 if data.adjust(self, expn_id).is_some() {
806 let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
807 let mut marks = Vec::new();
808 while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
809 marks.push(data.remove_mark(&mut glob_ctxt));
812 let scope = marks.last().map(|mark| mark.0);
813 while let Some((expn_id, transparency)) = marks.pop() {
814 *self = data.apply_mark(*self, expn_id, transparency);
820 pub fn hygienic_eq(self, other: SyntaxContext, expn_id: ExpnId) -> bool {
821 HygieneData::with(|data| {
822 let mut self_normalized = data.normalize_to_macros_2_0(self);
823 data.adjust(&mut self_normalized, expn_id);
824 self_normalized == data.normalize_to_macros_2_0(other)
829 pub fn normalize_to_macros_2_0(self) -> SyntaxContext {
830 HygieneData::with(|data| data.normalize_to_macros_2_0(self))
834 pub fn normalize_to_macro_rules(self) -> SyntaxContext {
835 HygieneData::with(|data| data.normalize_to_macro_rules(self))
839 pub fn outer_expn(self) -> ExpnId {
840 HygieneData::with(|data| data.outer_expn(self))
843 /// `ctxt.outer_expn_data()` is equivalent to but faster than
844 /// `ctxt.outer_expn().expn_data()`.
846 pub fn outer_expn_data(self) -> ExpnData {
847 HygieneData::with(|data| data.expn_data(data.outer_expn(self)).clone())
851 pub fn outer_mark(self) -> (ExpnId, Transparency) {
852 HygieneData::with(|data| data.outer_mark(self))
855 pub fn dollar_crate_name(self) -> Symbol {
856 HygieneData::with(|data| data.syntax_context_data[self.0 as usize].dollar_crate_name)
859 pub fn edition(self) -> Edition {
860 HygieneData::with(|data| data.expn_data(data.outer_expn(self)).edition)
864 impl fmt::Debug for SyntaxContext {
865 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
866 write!(f, "#{}", self.0)
871 /// Creates a fresh expansion with given properties.
872 /// Expansions are normally created by macros, but in some cases expansions are created for
873 /// other compiler-generated code to set per-span properties like allowed unstable features.
874 /// The returned span belongs to the created expansion and has the new properties,
875 /// but its location is inherited from the current span.
876 pub fn fresh_expansion(self, expn_id: LocalExpnId) -> Span {
877 HygieneData::with(|data| {
878 self.with_ctxt(data.apply_mark(
879 SyntaxContext::root(),
880 expn_id.to_expn_id(),
881 Transparency::Transparent,
886 /// Reuses the span but adds information like the kind of the desugaring and features that are
887 /// allowed inside this span.
888 pub fn mark_with_reason(
890 allow_internal_unstable: Option<Lrc<[Symbol]>>,
891 reason: DesugaringKind,
893 ctx: impl HashStableContext,
895 let expn_data = ExpnData {
896 allow_internal_unstable,
897 ..ExpnData::default(ExpnKind::Desugaring(reason), self, edition, None, None)
899 let expn_id = LocalExpnId::fresh(expn_data, ctx);
900 self.fresh_expansion(expn_id)
904 /// A subset of properties from both macro definition and macro call available through global data.
905 /// Avoid using this if you have access to the original definition or call structures.
906 #[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
907 pub struct ExpnData {
908 // --- The part unique to each expansion.
909 /// The kind of this expansion - macro or compiler desugaring.
911 /// The expansion that produced this expansion.
913 /// The location of the actual macro invocation or syntax sugar , e.g.
914 /// `let x = foo!();` or `if let Some(y) = x {}`
916 /// This may recursively refer to other macro invocations, e.g., if
917 /// `foo!()` invoked `bar!()` internally, and there was an
918 /// expression inside `bar!`; the call_site of the expression in
919 /// the expansion would point to the `bar!` invocation; that
920 /// call_site span would have its own ExpnData, with the call_site
921 /// pointing to the `foo!` invocation.
923 /// Used to force two `ExpnData`s to have different `Fingerprint`s.
924 /// Due to macro expansion, it's possible to end up with two `ExpnId`s
925 /// that have identical `ExpnData`s. This violates the contract of `HashStable`
926 /// - the two `ExpnId`s are not equal, but their `Fingerprint`s are equal
927 /// (since the numerical `ExpnId` value is not considered by the `HashStable`
930 /// The `disambiguator` field is set by `update_disambiguator` when two distinct
931 /// `ExpnId`s would end up with the same `Fingerprint`. Since `ExpnData` includes
932 /// a `krate` field, this value only needs to be unique within a single crate.
935 // --- The part specific to the macro/desugaring definition.
936 // --- It may be reasonable to share this part between expansions with the same definition,
937 // --- but such sharing is known to bring some minor inconveniences without also bringing
938 // --- noticeable perf improvements (PR #62898).
939 /// The span of the macro definition (possibly dummy).
940 /// This span serves only informational purpose and is not used for resolution.
942 /// List of `#[unstable]`/feature-gated features that the macro is allowed to use
943 /// internally without forcing the whole crate to opt-in
945 pub allow_internal_unstable: Option<Lrc<[Symbol]>>,
946 /// Edition of the crate in which the macro is defined.
947 pub edition: Edition,
948 /// The `DefId` of the macro being invoked,
949 /// if this `ExpnData` corresponds to a macro invocation
950 pub macro_def_id: Option<DefId>,
951 /// The normal module (`mod`) in which the expanded macro was defined.
952 pub parent_module: Option<DefId>,
953 /// Suppresses the `unsafe_code` lint for code produced by this macro.
954 pub allow_internal_unsafe: bool,
955 /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`) for this macro.
956 pub local_inner_macros: bool,
957 /// Should debuginfo for the macro be collapsed to the outermost expansion site (in other
958 /// words, was the macro definition annotated with `#[collapse_debuginfo]`)?
959 pub collapse_debuginfo: bool,
962 impl !PartialEq for ExpnData {}
963 impl !Hash for ExpnData {}
971 allow_internal_unstable: Option<Lrc<[Symbol]>>,
973 macro_def_id: Option<DefId>,
974 parent_module: Option<DefId>,
975 allow_internal_unsafe: bool,
976 local_inner_macros: bool,
977 collapse_debuginfo: bool,
984 allow_internal_unstable,
989 allow_internal_unsafe,
995 /// Constructs expansion data with default properties.
1000 macro_def_id: Option<DefId>,
1001 parent_module: Option<DefId>,
1005 parent: ExpnId::root(),
1008 allow_internal_unstable: None,
1013 allow_internal_unsafe: false,
1014 local_inner_macros: false,
1015 collapse_debuginfo: false,
1019 pub fn allow_unstable(
1023 allow_internal_unstable: Lrc<[Symbol]>,
1024 macro_def_id: Option<DefId>,
1025 parent_module: Option<DefId>,
1028 allow_internal_unstable: Some(allow_internal_unstable),
1029 ..ExpnData::default(kind, call_site, edition, macro_def_id, parent_module)
1034 pub fn is_root(&self) -> bool {
1035 matches!(self.kind, ExpnKind::Root)
1039 fn hash_expn(&self, ctx: &mut impl HashStableContext) -> u64 {
1040 let mut hasher = StableHasher::new();
1041 self.hash_stable(ctx, &mut hasher);
1047 #[derive(Clone, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
1049 /// No expansion, aka root expansion. Only `ExpnId::root()` has this kind.
1051 /// Expansion produced by a macro.
1052 Macro(MacroKind, Symbol),
1053 /// Transform done by the compiler on the AST.
1055 /// Desugaring done by the compiler during HIR lowering.
1056 Desugaring(DesugaringKind),
1062 pub fn descr(&self) -> String {
1064 ExpnKind::Root => kw::PathRoot.to_string(),
1065 ExpnKind::Macro(macro_kind, name) => match macro_kind {
1066 MacroKind::Bang => format!("{}!", name),
1067 MacroKind::Attr => format!("#[{}]", name),
1068 MacroKind::Derive => format!("#[derive({})]", name),
1070 ExpnKind::AstPass(kind) => kind.descr().to_string(),
1071 ExpnKind::Desugaring(kind) => format!("desugaring of {}", kind.descr()),
1072 ExpnKind::Inlined => "inlined source".to_string(),
1077 /// The kind of macro invocation or definition.
1078 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
1079 #[derive(HashStable_Generic)]
1080 pub enum MacroKind {
1081 /// A bang macro `foo!()`.
1083 /// An attribute macro `#[foo]`.
1085 /// A derive macro `#[derive(Foo)]`
1090 pub fn descr(self) -> &'static str {
1092 MacroKind::Bang => "macro",
1093 MacroKind::Attr => "attribute macro",
1094 MacroKind::Derive => "derive macro",
1098 pub fn descr_expected(self) -> &'static str {
1100 MacroKind::Attr => "attribute",
1105 pub fn article(self) -> &'static str {
1107 MacroKind::Attr => "an",
1113 /// The kind of AST transform.
1114 #[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
1122 pub fn descr(self) -> &'static str {
1124 AstPass::StdImports => "standard library imports",
1125 AstPass::TestHarness => "test harness",
1126 AstPass::ProcMacroHarness => "proc macro harness",
1131 /// The kind of compiler desugaring.
1132 #[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
1133 pub enum DesugaringKind {
1134 /// We desugar `if c { i } else { e }` to `match $ExprKind::Use(c) { true => i, _ => e }`.
1135 /// However, we do not want to blame `c` for unreachability but rather say that `i`
1136 /// is unreachable. This desugaring kind allows us to avoid blaming `c`.
1137 /// This also applies to `while` loops.
1142 /// Desugaring of an `impl Trait` in return type position
1143 /// to an `type Foo = impl Trait;` and replacing the
1144 /// `impl Trait` with `Foo`.
1152 impl DesugaringKind {
1153 /// The description wording should combine well with "desugaring of {}".
1154 pub fn descr(self) -> &'static str {
1156 DesugaringKind::CondTemporary => "`if` or `while` condition",
1157 DesugaringKind::Async => "`async` block or function",
1158 DesugaringKind::Await => "`await` expression",
1159 DesugaringKind::QuestionMark => "operator `?`",
1160 DesugaringKind::TryBlock => "`try` block",
1161 DesugaringKind::YeetExpr => "`do yeet` expression",
1162 DesugaringKind::OpaqueTy => "`impl Trait`",
1163 DesugaringKind::ForLoop => "`for` loop",
1164 DesugaringKind::WhileLoop => "`while` loop",
1170 pub struct HygieneEncodeContext {
1171 /// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
1172 /// This is `None` after we finish encoding `SyntaxContexts`, to ensure
1173 /// that we don't accidentally try to encode any more `SyntaxContexts`
1174 serialized_ctxts: Lock<FxHashSet<SyntaxContext>>,
1175 /// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
1176 /// in the most recent 'round' of serializing. Serializing `SyntaxContextData`
1177 /// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
1178 /// until we reach a fixed point.
1179 latest_ctxts: Lock<FxHashSet<SyntaxContext>>,
1181 serialized_expns: Lock<FxHashSet<ExpnId>>,
1183 latest_expns: Lock<FxHashSet<ExpnId>>,
1186 impl HygieneEncodeContext {
1187 /// Record the fact that we need to serialize the corresponding `ExpnData`.
1188 pub fn schedule_expn_data_for_encoding(&self, expn: ExpnId) {
1189 if !self.serialized_expns.lock().contains(&expn) {
1190 self.latest_expns.lock().insert(expn);
1197 mut encode_ctxt: impl FnMut(&mut T, u32, &SyntaxContextData),
1198 mut encode_expn: impl FnMut(&mut T, ExpnId, &ExpnData, ExpnHash),
1200 // When we serialize a `SyntaxContextData`, we may end up serializing
1201 // a `SyntaxContext` that we haven't seen before
1202 while !self.latest_ctxts.lock().is_empty() || !self.latest_expns.lock().is_empty() {
1204 "encode_hygiene: Serializing a round of {:?} SyntaxContextDatas: {:?}",
1205 self.latest_ctxts.lock().len(),
1209 // Consume the current round of SyntaxContexts.
1210 // Drop the lock() temporary early
1211 let latest_ctxts = { std::mem::take(&mut *self.latest_ctxts.lock()) };
1213 // It's fine to iterate over a HashMap, because the serialization
1214 // of the table that we insert data into doesn't depend on insertion
1216 #[allow(rustc::potential_query_instability)]
1217 for_all_ctxts_in(latest_ctxts.into_iter(), |index, ctxt, data| {
1218 if self.serialized_ctxts.lock().insert(ctxt) {
1219 encode_ctxt(encoder, index, data);
1223 let latest_expns = { std::mem::take(&mut *self.latest_expns.lock()) };
1225 // Same as above, this is fine as we are inserting into a order-independent hashset
1226 #[allow(rustc::potential_query_instability)]
1227 for_all_expns_in(latest_expns.into_iter(), |expn, data, hash| {
1228 if self.serialized_expns.lock().insert(expn) {
1229 encode_expn(encoder, expn, data, hash);
1233 debug!("encode_hygiene: Done serializing SyntaxContextData");
1238 /// Additional information used to assist in decoding hygiene data
1239 pub struct HygieneDecodeContext {
1240 // Maps serialized `SyntaxContext` ids to a `SyntaxContext` in the current
1241 // global `HygieneData`. When we deserialize a `SyntaxContext`, we need to create
1242 // a new id in the global `HygieneData`. This map tracks the ID we end up picking,
1243 // so that multiple occurrences of the same serialized id are decoded to the same
1245 remapped_ctxts: Lock<Vec<Option<SyntaxContext>>>,
1248 /// Register an expansion which has been decoded from the on-disk-cache for the local crate.
1249 pub fn register_local_expn_id(data: ExpnData, hash: ExpnHash) -> ExpnId {
1250 HygieneData::with(|hygiene_data| {
1251 let expn_id = hygiene_data.local_expn_data.next_index();
1252 hygiene_data.local_expn_data.push(Some(data));
1253 let _eid = hygiene_data.local_expn_hashes.push(hash);
1254 debug_assert_eq!(expn_id, _eid);
1256 let expn_id = expn_id.to_expn_id();
1258 let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
1259 debug_assert!(_old_id.is_none());
1264 /// Register an expansion which has been decoded from the metadata of a foreign crate.
1265 pub fn register_expn_id(
1267 local_id: ExpnIndex,
1271 debug_assert!(data.parent == ExpnId::root() || krate == data.parent.krate);
1272 let expn_id = ExpnId { krate, local_id };
1273 HygieneData::with(|hygiene_data| {
1274 let _old_data = hygiene_data.foreign_expn_data.insert(expn_id, data);
1275 debug_assert!(_old_data.is_none());
1276 let _old_hash = hygiene_data.foreign_expn_hashes.insert(expn_id, hash);
1277 debug_assert!(_old_hash.is_none());
1278 let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
1279 debug_assert!(_old_id.is_none());
1284 /// Decode an expansion from the metadata of a foreign crate.
1285 pub fn decode_expn_id(
1288 decode_data: impl FnOnce(ExpnId) -> (ExpnData, ExpnHash),
1291 debug!("decode_expn_id: deserialized root");
1292 return ExpnId::root();
1295 let index = ExpnIndex::from_u32(index);
1297 // This function is used to decode metadata, so it cannot decode information about LOCAL_CRATE.
1298 debug_assert_ne!(krate, LOCAL_CRATE);
1299 let expn_id = ExpnId { krate, local_id: index };
1301 // Fast path if the expansion has already been decoded.
1302 if HygieneData::with(|hygiene_data| hygiene_data.foreign_expn_data.contains_key(&expn_id)) {
1306 // Don't decode the data inside `HygieneData::with`, since we need to recursively decode
1308 let (expn_data, hash) = decode_data(expn_id);
1310 register_expn_id(krate, index, expn_data, hash)
1313 // Decodes `SyntaxContext`, using the provided `HygieneDecodeContext`
1314 // to track which `SyntaxContext`s we have already decoded.
1315 // The provided closure will be invoked to deserialize a `SyntaxContextData`
1316 // if we haven't already seen the id of the `SyntaxContext` we are deserializing.
1317 pub fn decode_syntax_context<D: Decoder, F: FnOnce(&mut D, u32) -> SyntaxContextData>(
1319 context: &HygieneDecodeContext,
1321 ) -> SyntaxContext {
1322 let raw_id: u32 = Decodable::decode(d);
1324 debug!("decode_syntax_context: deserialized root");
1325 // The root is special
1326 return SyntaxContext::root();
1329 let outer_ctxts = &context.remapped_ctxts;
1331 // Ensure that the lock() temporary is dropped early
1333 if let Some(ctxt) = outer_ctxts.lock().get(raw_id as usize).copied().flatten() {
1338 // Allocate and store SyntaxContext id *before* calling the decoder function,
1339 // as the SyntaxContextData may reference itself.
1340 let new_ctxt = HygieneData::with(|hygiene_data| {
1341 let new_ctxt = SyntaxContext(hygiene_data.syntax_context_data.len() as u32);
1342 // Push a dummy SyntaxContextData to ensure that nobody else can get the
1343 // same ID as us. This will be overwritten after call `decode_Data`
1344 hygiene_data.syntax_context_data.push(SyntaxContextData {
1345 outer_expn: ExpnId::root(),
1346 outer_transparency: Transparency::Transparent,
1347 parent: SyntaxContext::root(),
1348 opaque: SyntaxContext::root(),
1349 opaque_and_semitransparent: SyntaxContext::root(),
1350 dollar_crate_name: kw::Empty,
1352 let mut ctxts = outer_ctxts.lock();
1353 let new_len = raw_id as usize + 1;
1354 if ctxts.len() < new_len {
1355 ctxts.resize(new_len, None);
1357 ctxts[raw_id as usize] = Some(new_ctxt);
1362 // Don't try to decode data while holding the lock, since we need to
1363 // be able to recursively decode a SyntaxContext
1364 let mut ctxt_data = decode_data(d, raw_id);
1365 // Reset `dollar_crate_name` so that it will be updated by `update_dollar_crate_names`
1366 // We don't care what the encoding crate set this to - we want to resolve it
1367 // from the perspective of the current compilation session
1368 ctxt_data.dollar_crate_name = kw::DollarCrate;
1370 // Overwrite the dummy data with our decoded SyntaxContextData
1371 HygieneData::with(|hygiene_data| {
1372 let dummy = std::mem::replace(
1373 &mut hygiene_data.syntax_context_data[new_ctxt.as_u32() as usize],
1376 // Make sure nothing weird happening while `decode_data` was running
1377 assert_eq!(dummy.dollar_crate_name, kw::Empty);
1383 fn for_all_ctxts_in<F: FnMut(u32, SyntaxContext, &SyntaxContextData)>(
1384 ctxts: impl Iterator<Item = SyntaxContext>,
1387 let all_data: Vec<_> = HygieneData::with(|data| {
1388 ctxts.map(|ctxt| (ctxt, data.syntax_context_data[ctxt.0 as usize].clone())).collect()
1390 for (ctxt, data) in all_data.into_iter() {
1391 f(ctxt.0, ctxt, &data);
1395 fn for_all_expns_in(
1396 expns: impl Iterator<Item = ExpnId>,
1397 mut f: impl FnMut(ExpnId, &ExpnData, ExpnHash),
1399 let all_data: Vec<_> = HygieneData::with(|data| {
1400 expns.map(|expn| (expn, data.expn_data(expn).clone(), data.expn_hash(expn))).collect()
1402 for (expn, data, hash) in all_data.into_iter() {
1403 f(expn, &data, hash);
1407 impl<E: Encoder> Encodable<E> for LocalExpnId {
1408 fn encode(&self, e: &mut E) {
1409 self.to_expn_id().encode(e);
1413 impl<E: Encoder> Encodable<E> for ExpnId {
1414 default fn encode(&self, _: &mut E) {
1415 panic!("cannot encode `ExpnId` with `{}`", std::any::type_name::<E>());
1419 impl<D: Decoder> Decodable<D> for LocalExpnId {
1420 fn decode(d: &mut D) -> Self {
1421 ExpnId::expect_local(ExpnId::decode(d))
1425 impl<D: Decoder> Decodable<D> for ExpnId {
1426 default fn decode(_: &mut D) -> Self {
1427 panic!("cannot decode `ExpnId` with `{}`", std::any::type_name::<D>());
1431 pub fn raw_encode_syntax_context<E: Encoder>(
1432 ctxt: SyntaxContext,
1433 context: &HygieneEncodeContext,
1436 if !context.serialized_ctxts.lock().contains(&ctxt) {
1437 context.latest_ctxts.lock().insert(ctxt);
1442 impl<E: Encoder> Encodable<E> for SyntaxContext {
1443 default fn encode(&self, _: &mut E) {
1444 panic!("cannot encode `SyntaxContext` with `{}`", std::any::type_name::<E>());
1448 impl<D: Decoder> Decodable<D> for SyntaxContext {
1449 default fn decode(_: &mut D) -> Self {
1450 panic!("cannot decode `SyntaxContext` with `{}`", std::any::type_name::<D>());
1454 /// Updates the `disambiguator` field of the corresponding `ExpnData`
1455 /// such that the `Fingerprint` of the `ExpnData` does not collide with
1456 /// any other `ExpnIds`.
1458 /// This method is called only when an `ExpnData` is first associated
1459 /// with an `ExpnId` (when the `ExpnId` is initially constructed, or via
1460 /// `set_expn_data`). It is *not* called for foreign `ExpnId`s deserialized
1461 /// from another crate's metadata - since `ExpnHash` includes the stable crate id,
1462 /// collisions are only possible between `ExpnId`s within the same crate.
1463 fn update_disambiguator(expn_data: &mut ExpnData, mut ctx: impl HashStableContext) -> ExpnHash {
1464 // This disambiguator should not have been set yet.
1466 expn_data.disambiguator, 0,
1467 "Already set disambiguator for ExpnData: {:?}",
1470 assert_default_hashing_controls(&ctx, "ExpnData (disambiguator)");
1471 let mut expn_hash = expn_data.hash_expn(&mut ctx);
1473 let disambiguator = HygieneData::with(|data| {
1474 // If this is the first ExpnData with a given hash, then keep our
1475 // disambiguator at 0 (the default u32 value)
1476 let disambig = data.expn_data_disambiguators.entry(expn_hash).or_default();
1477 let disambiguator = *disambig;
1482 if disambiguator != 0 {
1483 debug!("Set disambiguator for expn_data={:?} expn_hash={:?}", expn_data, expn_hash);
1485 expn_data.disambiguator = disambiguator;
1486 expn_hash = expn_data.hash_expn(&mut ctx);
1488 // Verify that the new disambiguator makes the hash unique
1489 #[cfg(debug_assertions)]
1490 HygieneData::with(|data| {
1492 data.expn_data_disambiguators.get(&expn_hash),
1494 "Hash collision after disambiguator update!",
1499 ExpnHash::new(ctx.def_path_hash(LOCAL_CRATE.as_def_id()).stable_crate_id(), expn_hash)
1502 impl<CTX: HashStableContext> HashStable<CTX> for SyntaxContext {
1503 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1504 const TAG_EXPANSION: u8 = 0;
1505 const TAG_NO_EXPANSION: u8 = 1;
1507 if *self == SyntaxContext::root() {
1508 TAG_NO_EXPANSION.hash_stable(ctx, hasher);
1510 TAG_EXPANSION.hash_stable(ctx, hasher);
1511 let (expn_id, transparency) = self.outer_mark();
1512 expn_id.hash_stable(ctx, hasher);
1513 transparency.hash_stable(ctx, hasher);
1518 impl<CTX: HashStableContext> HashStable<CTX> for ExpnId {
1519 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1520 assert_default_hashing_controls(ctx, "ExpnId");
1521 let hash = if *self == ExpnId::root() {
1522 // Avoid fetching TLS storage for a trivial often-used value.
1528 hash.hash_stable(ctx, hasher);