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::{HashStable, StableHasher};
36 use rustc_data_structures::sync::{Lock, Lrc};
37 use rustc_data_structures::unhash::UnhashMap;
38 use rustc_index::vec::IndexVec;
39 use rustc_macros::HashStable_Generic;
40 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.
64 pub struct ExpnIndex {
69 /// A unique ID associated with a macro invocation and expansion.
70 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
73 pub local_id: ExpnIndex,
76 impl fmt::Debug for ExpnId {
77 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
78 // Generate crate_::{{expn_}}.
79 write!(f, "{:?}::{{{{expn{}}}}}", self.krate, self.local_id.private)
83 rustc_index::newtype_index! {
84 /// A unique ID associated with a macro invocation and expansion.
85 pub struct LocalExpnId {
87 DEBUG_FORMAT = "expn{}"
91 /// A unique hash value associated to an expansion.
92 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, Encodable, Decodable, HashStable_Generic)]
93 pub struct ExpnHash(Fingerprint);
96 /// Returns the [StableCrateId] identifying the crate this [ExpnHash]
99 pub fn stable_crate_id(self) -> StableCrateId {
100 StableCrateId(self.0.as_value().0)
103 /// Returns the crate-local part of the [ExpnHash].
107 pub fn local_hash(self) -> u64 {
112 pub fn is_root(self) -> bool {
113 self.0 == Fingerprint::ZERO
116 /// Builds a new [ExpnHash] with the given [StableCrateId] and
117 /// `local_hash`, where `local_hash` must be unique within its crate.
118 fn new(stable_crate_id: StableCrateId, local_hash: u64) -> ExpnHash {
119 ExpnHash(Fingerprint::new(stable_crate_id.0, local_hash))
123 /// A property of a macro expansion that determines how identifiers
124 /// produced by that expansion are resolved.
125 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Hash, Debug, Encodable, Decodable)]
126 #[derive(HashStable_Generic)]
127 pub enum Transparency {
128 /// Identifier produced by a transparent expansion is always resolved at call-site.
129 /// Call-site spans in procedural macros, hygiene opt-out in `macro` should use this.
131 /// Identifier produced by a semi-transparent expansion may be resolved
132 /// either at call-site or at definition-site.
133 /// If it's a local variable, label or `$crate` then it's resolved at def-site.
134 /// Otherwise it's resolved at call-site.
135 /// `macro_rules` macros behave like this, built-in macros currently behave like this too,
136 /// but that's an implementation detail.
138 /// Identifier produced by an opaque expansion is always resolved at definition-site.
139 /// Def-site spans in procedural macros, identifiers from `macro` by default use this.
144 /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
145 pub const ROOT: LocalExpnId = LocalExpnId::from_u32(0);
147 pub fn from_raw(idx: ExpnIndex) -> LocalExpnId {
148 LocalExpnId::from_u32(idx.as_u32())
151 pub fn as_raw(self) -> ExpnIndex {
152 ExpnIndex::from_u32(self.as_u32())
155 pub fn fresh_empty() -> LocalExpnId {
156 HygieneData::with(|data| data.fresh_expn(None))
159 pub fn fresh(expn_data: ExpnData, ctx: impl HashStableContext) -> LocalExpnId {
160 debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
161 let expn_id = HygieneData::with(|data| data.fresh_expn(Some(expn_data)));
162 update_disambiguator(expn_id, ctx);
167 pub fn expn_hash(self) -> ExpnHash {
168 HygieneData::with(|data| data.local_expn_hash(self))
172 pub fn expn_data(self) -> ExpnData {
173 HygieneData::with(|data| data.local_expn_data(self).clone())
177 pub fn to_expn_id(self) -> ExpnId {
178 ExpnId { krate: LOCAL_CRATE, local_id: self.as_raw() }
182 pub fn set_expn_data(self, mut expn_data: ExpnData, ctx: impl HashStableContext) {
183 debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
184 HygieneData::with(|data| {
185 let old_expn_data = &mut data.local_expn_data[self];
186 assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
187 assert_eq!(expn_data.orig_id, None);
188 debug_assert_eq!(expn_data.krate, LOCAL_CRATE);
189 expn_data.orig_id = Some(self.as_u32());
190 *old_expn_data = Some(expn_data);
192 update_disambiguator(self, ctx)
196 pub fn is_descendant_of(self, ancestor: LocalExpnId) -> bool {
197 self.to_expn_id().is_descendant_of(ancestor.to_expn_id())
200 /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
201 /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
203 pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
204 self.to_expn_id().outer_expn_is_descendant_of(ctxt)
207 /// Returns span for the macro which originally caused this expansion to happen.
209 /// Stops backtracing at include! boundary.
211 pub fn expansion_cause(self) -> Option<Span> {
212 self.to_expn_id().expansion_cause()
217 pub fn parent(self) -> LocalExpnId {
218 self.expn_data().parent.as_local().unwrap()
223 /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
224 /// Invariant: we do not create any ExpnId with local_id == 0 and krate != 0.
225 pub const fn root() -> ExpnId {
226 ExpnId { krate: LOCAL_CRATE, local_id: ExpnIndex::from_u32(0) }
230 pub fn expn_hash(self) -> ExpnHash {
231 HygieneData::with(|data| data.expn_hash(self))
235 pub fn from_hash(hash: ExpnHash) -> Option<ExpnId> {
236 HygieneData::with(|data| data.expn_hash_to_expn_id.get(&hash).copied())
240 pub fn as_local(self) -> Option<LocalExpnId> {
241 if self.krate == LOCAL_CRATE { Some(LocalExpnId::from_raw(self.local_id)) } else { None }
246 pub fn expect_local(self) -> LocalExpnId {
247 self.as_local().unwrap()
251 pub fn expn_data(self) -> ExpnData {
252 HygieneData::with(|data| data.expn_data(self).clone())
255 pub fn is_descendant_of(self, ancestor: ExpnId) -> bool {
256 HygieneData::with(|data| data.is_descendant_of(self, ancestor))
259 /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
260 /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
261 pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
262 HygieneData::with(|data| data.is_descendant_of(self, data.outer_expn(ctxt)))
265 /// Returns span for the macro which originally caused this expansion to happen.
267 /// Stops backtracing at include! boundary.
268 pub fn expansion_cause(mut self) -> Option<Span> {
269 let mut last_macro = None;
271 let expn_data = self.expn_data();
272 // Stop going up the backtrace once include! is encountered
273 if expn_data.is_root()
274 || expn_data.kind == ExpnKind::Macro(MacroKind::Bang, sym::include)
278 self = expn_data.call_site.ctxt().outer_expn();
279 last_macro = Some(expn_data.call_site);
286 pub struct HygieneData {
287 /// Each expansion should have an associated expansion data, but sometimes there's a delay
288 /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
289 /// first and then resolved later), so we use an `Option` here.
290 local_expn_data: IndexVec<LocalExpnId, Option<ExpnData>>,
291 local_expn_hashes: IndexVec<LocalExpnId, ExpnHash>,
292 /// Data and hash information from external crates. We may eventually want to remove these
293 /// maps, and fetch the information directly from the other crate's metadata like DefIds do.
294 foreign_expn_data: FxHashMap<ExpnId, ExpnData>,
295 foreign_expn_hashes: FxHashMap<ExpnId, ExpnHash>,
296 expn_hash_to_expn_id: UnhashMap<ExpnHash, ExpnId>,
297 syntax_context_data: Vec<SyntaxContextData>,
298 syntax_context_map: FxHashMap<(SyntaxContext, ExpnId, Transparency), SyntaxContext>,
299 /// Maps the `local_hash` of an `ExpnData` to the next disambiguator value.
300 /// This is used by `update_disambiguator` to keep track of which `ExpnData`s
301 /// would have collisions without a disambiguator.
302 /// The keys of this map are always computed with `ExpnData.disambiguator`
304 expn_data_disambiguators: FxHashMap<u64, u32>,
308 crate fn new(edition: Edition) -> Self {
309 let mut root_data = ExpnData::default(
313 Some(CRATE_DEF_ID.to_def_id()),
316 root_data.orig_id = Some(0);
319 local_expn_data: IndexVec::from_elem_n(Some(root_data), 1),
320 local_expn_hashes: IndexVec::from_elem_n(ExpnHash(Fingerprint::ZERO), 1),
321 foreign_expn_data: FxHashMap::default(),
322 foreign_expn_hashes: FxHashMap::default(),
323 expn_hash_to_expn_id: std::iter::once((ExpnHash(Fingerprint::ZERO), ExpnId::root()))
325 syntax_context_data: vec![SyntaxContextData {
326 outer_expn: ExpnId::root(),
327 outer_transparency: Transparency::Opaque,
328 parent: SyntaxContext(0),
329 opaque: SyntaxContext(0),
330 opaque_and_semitransparent: SyntaxContext(0),
331 dollar_crate_name: kw::DollarCrate,
333 syntax_context_map: FxHashMap::default(),
334 expn_data_disambiguators: FxHashMap::default(),
338 pub fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
339 with_session_globals(|session_globals| f(&mut *session_globals.hygiene_data.borrow_mut()))
342 fn fresh_expn(&mut self, mut expn_data: Option<ExpnData>) -> LocalExpnId {
343 let expn_id = self.local_expn_data.next_index();
344 if let Some(data) = expn_data.as_mut() {
345 debug_assert_eq!(data.krate, LOCAL_CRATE);
346 assert_eq!(data.orig_id, None);
347 data.orig_id = Some(expn_id.as_u32());
349 self.local_expn_data.push(expn_data);
350 let _eid = self.local_expn_hashes.push(ExpnHash(Fingerprint::ZERO));
351 debug_assert_eq!(expn_id, _eid);
356 fn local_expn_hash(&self, expn_id: LocalExpnId) -> ExpnHash {
357 self.local_expn_hashes[expn_id]
361 fn expn_hash(&self, expn_id: ExpnId) -> ExpnHash {
362 match expn_id.as_local() {
363 Some(expn_id) => self.local_expn_hashes[expn_id],
364 None => self.foreign_expn_hashes[&expn_id],
368 fn local_expn_data(&self, expn_id: LocalExpnId) -> &ExpnData {
369 self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
372 fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
373 if let Some(expn_id) = expn_id.as_local() {
374 self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
376 &self.foreign_expn_data[&expn_id]
380 fn is_descendant_of(&self, mut expn_id: ExpnId, ancestor: ExpnId) -> bool {
381 while expn_id != ancestor {
382 if expn_id == ExpnId::root() {
385 expn_id = self.expn_data(expn_id).parent;
390 fn normalize_to_macros_2_0(&self, ctxt: SyntaxContext) -> SyntaxContext {
391 self.syntax_context_data[ctxt.0 as usize].opaque
394 fn normalize_to_macro_rules(&self, ctxt: SyntaxContext) -> SyntaxContext {
395 self.syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent
398 fn outer_expn(&self, ctxt: SyntaxContext) -> ExpnId {
399 self.syntax_context_data[ctxt.0 as usize].outer_expn
402 fn outer_mark(&self, ctxt: SyntaxContext) -> (ExpnId, Transparency) {
403 let data = &self.syntax_context_data[ctxt.0 as usize];
404 (data.outer_expn, data.outer_transparency)
407 fn parent_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext {
408 self.syntax_context_data[ctxt.0 as usize].parent
411 fn remove_mark(&self, ctxt: &mut SyntaxContext) -> (ExpnId, Transparency) {
412 let outer_mark = self.outer_mark(*ctxt);
413 *ctxt = self.parent_ctxt(*ctxt);
417 fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
418 let mut marks = Vec::new();
419 while ctxt != SyntaxContext::root() {
420 debug!("marks: getting parent of {:?}", ctxt);
421 marks.push(self.outer_mark(ctxt));
422 ctxt = self.parent_ctxt(ctxt);
428 fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span {
429 debug!("walk_chain({:?}, {:?})", span, to);
430 debug!("walk_chain: span ctxt = {:?}", span.ctxt());
431 while span.from_expansion() && span.ctxt() != to {
432 let outer_expn = self.outer_expn(span.ctxt());
433 debug!("walk_chain({:?}): outer_expn={:?}", span, outer_expn);
434 let expn_data = self.expn_data(outer_expn);
435 debug!("walk_chain({:?}): expn_data={:?}", span, expn_data);
436 span = expn_data.call_site;
441 fn adjust(&self, ctxt: &mut SyntaxContext, expn_id: ExpnId) -> Option<ExpnId> {
442 let mut scope = None;
443 while !self.is_descendant_of(expn_id, self.outer_expn(*ctxt)) {
444 scope = Some(self.remove_mark(ctxt).0);
453 transparency: Transparency,
455 assert_ne!(expn_id, ExpnId::root());
456 if transparency == Transparency::Opaque {
457 return self.apply_mark_internal(ctxt, expn_id, transparency);
460 let call_site_ctxt = self.expn_data(expn_id).call_site.ctxt();
461 let mut call_site_ctxt = if transparency == Transparency::SemiTransparent {
462 self.normalize_to_macros_2_0(call_site_ctxt)
464 self.normalize_to_macro_rules(call_site_ctxt)
467 if call_site_ctxt == SyntaxContext::root() {
468 return self.apply_mark_internal(ctxt, expn_id, transparency);
471 // Otherwise, `expn_id` is a macros 1.0 definition and the call site is in a
472 // macros 2.0 expansion, i.e., a macros 1.0 invocation is in a macros 2.0 definition.
474 // In this case, the tokens from the macros 1.0 definition inherit the hygiene
475 // at their invocation. That is, we pretend that the macros 1.0 definition
476 // was defined at its invocation (i.e., inside the macros 2.0 definition)
477 // so that the macros 2.0 definition remains hygienic.
479 // See the example at `test/ui/hygiene/legacy_interaction.rs`.
480 for (expn_id, transparency) in self.marks(ctxt) {
481 call_site_ctxt = self.apply_mark_internal(call_site_ctxt, expn_id, transparency);
483 self.apply_mark_internal(call_site_ctxt, expn_id, transparency)
486 fn apply_mark_internal(
490 transparency: Transparency,
492 let syntax_context_data = &mut self.syntax_context_data;
493 let mut opaque = syntax_context_data[ctxt.0 as usize].opaque;
494 let mut opaque_and_semitransparent =
495 syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent;
497 if transparency >= Transparency::Opaque {
501 .entry((parent, expn_id, transparency))
503 let new_opaque = SyntaxContext(syntax_context_data.len() as u32);
504 syntax_context_data.push(SyntaxContextData {
506 outer_transparency: transparency,
509 opaque_and_semitransparent: new_opaque,
510 dollar_crate_name: kw::DollarCrate,
516 if transparency >= Transparency::SemiTransparent {
517 let parent = opaque_and_semitransparent;
518 opaque_and_semitransparent = *self
520 .entry((parent, expn_id, transparency))
522 let new_opaque_and_semitransparent =
523 SyntaxContext(syntax_context_data.len() as u32);
524 syntax_context_data.push(SyntaxContextData {
526 outer_transparency: transparency,
529 opaque_and_semitransparent: new_opaque_and_semitransparent,
530 dollar_crate_name: kw::DollarCrate,
532 new_opaque_and_semitransparent
537 *self.syntax_context_map.entry((parent, expn_id, transparency)).or_insert_with(|| {
538 let new_opaque_and_semitransparent_and_transparent =
539 SyntaxContext(syntax_context_data.len() as u32);
540 syntax_context_data.push(SyntaxContextData {
542 outer_transparency: transparency,
545 opaque_and_semitransparent,
546 dollar_crate_name: kw::DollarCrate,
548 new_opaque_and_semitransparent_and_transparent
553 pub fn clear_syntax_context_map() {
554 HygieneData::with(|data| data.syntax_context_map = FxHashMap::default());
557 pub fn walk_chain(span: Span, to: SyntaxContext) -> Span {
558 HygieneData::with(|data| data.walk_chain(span, to))
561 pub fn update_dollar_crate_names(mut get_name: impl FnMut(SyntaxContext) -> Symbol) {
562 // The new contexts that need updating are at the end of the list and have `$crate` as a name.
563 let (len, to_update) = HygieneData::with(|data| {
565 data.syntax_context_data.len(),
566 data.syntax_context_data
569 .take_while(|scdata| scdata.dollar_crate_name == kw::DollarCrate)
573 // The callback must be called from outside of the `HygieneData` lock,
574 // since it will try to acquire it too.
575 let range_to_update = len - to_update..len;
577 range_to_update.clone().map(|idx| get_name(SyntaxContext::from_u32(idx as u32))).collect();
578 HygieneData::with(|data| {
579 range_to_update.zip(names).for_each(|(idx, name)| {
580 data.syntax_context_data[idx].dollar_crate_name = name;
585 pub fn debug_hygiene_data(verbose: bool) -> String {
586 HygieneData::with(|data| {
588 format!("{:#?}", data)
590 let mut s = String::from("");
591 s.push_str("Expansions:");
592 let mut debug_expn_data = |(id, expn_info): (&ExpnId, &ExpnData)| {
594 "\n{:?}: parent: {:?}, call_site_ctxt: {:?}, def_site_ctxt: {:?}, kind: {:?}",
597 expn_info.call_site.ctxt(),
598 expn_info.def_site.ctxt(),
602 data.local_expn_data.iter_enumerated().for_each(|(id, expn_info)| {
603 let expn_info = expn_info.as_ref().expect("no expansion data for an expansion ID");
604 debug_expn_data((&id.to_expn_id(), expn_info))
606 data.foreign_expn_data.iter().for_each(debug_expn_data);
607 s.push_str("\n\nSyntaxContexts:");
608 data.syntax_context_data.iter().enumerate().for_each(|(id, ctxt)| {
610 "\n#{}: parent: {:?}, outer_mark: ({:?}, {:?})",
611 id, ctxt.parent, ctxt.outer_expn, ctxt.outer_transparency,
621 pub const fn root() -> Self {
626 crate fn as_u32(self) -> u32 {
631 crate fn from_u32(raw: u32) -> SyntaxContext {
635 /// Extend a syntax context with a given expansion and transparency.
636 crate fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext {
637 HygieneData::with(|data| data.apply_mark(self, expn_id, transparency))
640 /// Pulls a single mark off of the syntax context. This effectively moves the
641 /// context up one macro definition level. That is, if we have a nested macro
642 /// definition as follows:
652 /// and we have a SyntaxContext that is referring to something declared by an invocation
653 /// of g (call it g1), calling remove_mark will result in the SyntaxContext for the
654 /// invocation of f that created g1.
655 /// Returns the mark that was removed.
656 pub fn remove_mark(&mut self) -> ExpnId {
657 HygieneData::with(|data| data.remove_mark(self).0)
660 pub fn marks(self) -> Vec<(ExpnId, Transparency)> {
661 HygieneData::with(|data| data.marks(self))
664 /// Adjust this context for resolution in a scope created by the given expansion.
665 /// For example, consider the following three resolutions of `f`:
668 /// mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
670 /// macro m($f:ident) {
672 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
673 /// pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
675 /// foo::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
676 /// //^ Since `mod foo` is outside this expansion, `adjust` removes the mark from `f`,
677 /// //| and it resolves to `::foo::f`.
678 /// bar::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
679 /// //^ Since `mod bar` not outside this expansion, `adjust` does not change `f`,
680 /// //| and it resolves to `::bar::f`.
681 /// bar::$f(); // `f`'s `SyntaxContext` is empty.
682 /// //^ Since `mod bar` is not outside this expansion, `adjust` does not change `$f`,
683 /// //| and it resolves to `::bar::$f`.
686 /// This returns the expansion whose definition scope we use to privacy check the resolution,
687 /// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope).
688 pub fn adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
689 HygieneData::with(|data| data.adjust(self, expn_id))
692 /// Like `SyntaxContext::adjust`, but also normalizes `self` to macros 2.0.
693 pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
694 HygieneData::with(|data| {
695 *self = data.normalize_to_macros_2_0(*self);
696 data.adjust(self, expn_id)
700 /// Adjust this context for resolution in a scope created by the given expansion
701 /// via a glob import with the given `SyntaxContext`.
706 /// macro m($i:ident) {
708 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
709 /// pub fn $i() {} // `$i`'s `SyntaxContext` is empty.
712 /// macro n($j:ident) {
714 /// f(); // `f`'s `SyntaxContext` has a mark from `m` and a mark from `n`
715 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::f`.
716 /// $i(); // `$i`'s `SyntaxContext` has a mark from `n`
717 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::$i`.
718 /// $j(); // `$j`'s `SyntaxContext` has a mark from `m`
719 /// //^ This cannot be glob-adjusted, so this is a resolution error.
723 /// This returns `None` if the context cannot be glob-adjusted.
724 /// Otherwise, it returns the scope to use when privacy checking (see `adjust` for details).
725 pub fn glob_adjust(&mut self, expn_id: ExpnId, glob_span: Span) -> Option<Option<ExpnId>> {
726 HygieneData::with(|data| {
727 let mut scope = None;
728 let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
729 while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
730 scope = Some(data.remove_mark(&mut glob_ctxt).0);
731 if data.remove_mark(self).0 != scope.unwrap() {
735 if data.adjust(self, expn_id).is_some() {
742 /// Undo `glob_adjust` if possible:
745 /// if let Some(privacy_checking_scope) = self.reverse_glob_adjust(expansion, glob_ctxt) {
746 /// assert!(self.glob_adjust(expansion, glob_ctxt) == Some(privacy_checking_scope));
749 pub fn reverse_glob_adjust(
753 ) -> Option<Option<ExpnId>> {
754 HygieneData::with(|data| {
755 if data.adjust(self, expn_id).is_some() {
759 let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
760 let mut marks = Vec::new();
761 while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
762 marks.push(data.remove_mark(&mut glob_ctxt));
765 let scope = marks.last().map(|mark| mark.0);
766 while let Some((expn_id, transparency)) = marks.pop() {
767 *self = data.apply_mark(*self, expn_id, transparency);
773 pub fn hygienic_eq(self, other: SyntaxContext, expn_id: ExpnId) -> bool {
774 HygieneData::with(|data| {
775 let mut self_normalized = data.normalize_to_macros_2_0(self);
776 data.adjust(&mut self_normalized, expn_id);
777 self_normalized == data.normalize_to_macros_2_0(other)
782 pub fn normalize_to_macros_2_0(self) -> SyntaxContext {
783 HygieneData::with(|data| data.normalize_to_macros_2_0(self))
787 pub fn normalize_to_macro_rules(self) -> SyntaxContext {
788 HygieneData::with(|data| data.normalize_to_macro_rules(self))
792 pub fn outer_expn(self) -> ExpnId {
793 HygieneData::with(|data| data.outer_expn(self))
796 /// `ctxt.outer_expn_data()` is equivalent to but faster than
797 /// `ctxt.outer_expn().expn_data()`.
799 pub fn outer_expn_data(self) -> ExpnData {
800 HygieneData::with(|data| data.expn_data(data.outer_expn(self)).clone())
804 pub fn outer_mark(self) -> (ExpnId, Transparency) {
805 HygieneData::with(|data| data.outer_mark(self))
808 pub fn dollar_crate_name(self) -> Symbol {
809 HygieneData::with(|data| data.syntax_context_data[self.0 as usize].dollar_crate_name)
812 pub fn edition(self) -> Edition {
813 HygieneData::with(|data| data.expn_data(data.outer_expn(self)).edition)
817 impl fmt::Debug for SyntaxContext {
818 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
819 write!(f, "#{}", self.0)
824 /// Creates a fresh expansion with given properties.
825 /// Expansions are normally created by macros, but in some cases expansions are created for
826 /// other compiler-generated code to set per-span properties like allowed unstable features.
827 /// The returned span belongs to the created expansion and has the new properties,
828 /// but its location is inherited from the current span.
829 pub fn fresh_expansion(self, expn_data: ExpnData, ctx: impl HashStableContext) -> Span {
830 self.fresh_expansion_with_transparency(expn_data, Transparency::Transparent, ctx)
833 pub fn fresh_expansion_with_transparency(
836 transparency: Transparency,
837 ctx: impl HashStableContext,
839 let expn_id = LocalExpnId::fresh(expn_data, ctx).to_expn_id();
840 HygieneData::with(|data| {
841 self.with_ctxt(data.apply_mark(SyntaxContext::root(), expn_id, transparency))
845 /// Reuses the span but adds information like the kind of the desugaring and features that are
846 /// allowed inside this span.
847 pub fn mark_with_reason(
849 allow_internal_unstable: Option<Lrc<[Symbol]>>,
850 reason: DesugaringKind,
852 ctx: impl HashStableContext,
854 let expn_data = ExpnData {
855 allow_internal_unstable,
856 ..ExpnData::default(ExpnKind::Desugaring(reason), self, edition, None, None)
858 self.fresh_expansion(expn_data, ctx)
862 /// A subset of properties from both macro definition and macro call available through global data.
863 /// Avoid using this if you have access to the original definition or call structures.
864 #[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
865 pub struct ExpnData {
866 // --- The part unique to each expansion.
867 /// The kind of this expansion - macro or compiler desugaring.
869 /// The expansion that produced this expansion.
871 /// The location of the actual macro invocation or syntax sugar , e.g.
872 /// `let x = foo!();` or `if let Some(y) = x {}`
874 /// This may recursively refer to other macro invocations, e.g., if
875 /// `foo!()` invoked `bar!()` internally, and there was an
876 /// expression inside `bar!`; the call_site of the expression in
877 /// the expansion would point to the `bar!` invocation; that
878 /// call_site span would have its own ExpnData, with the call_site
879 /// pointing to the `foo!` invocation.
881 /// The crate that originally created this `ExpnData`. During
882 /// metadata serialization, we only encode `ExpnData`s that were
883 /// created locally - when our serialized metadata is decoded,
884 /// foreign `ExpnId`s will have their `ExpnData` looked up
885 /// from the crate specified by `Crate
887 /// The raw that this `ExpnData` had in its original crate.
888 /// An `ExpnData` can be created before being assigned an `ExpnId`,
889 /// so this might be `None` until `set_expn_data` is called
890 // This is used only for serialization/deserialization purposes:
891 // two `ExpnData`s that differ only in their `orig_id` should
892 // be considered equivalent.
893 #[stable_hasher(ignore)]
894 orig_id: Option<u32>,
895 /// Used to force two `ExpnData`s to have different `Fingerprint`s.
896 /// Due to macro expansion, it's possible to end up with two `ExpnId`s
897 /// that have identical `ExpnData`s. This violates the contract of `HashStable`
898 /// - the two `ExpnId`s are not equal, but their `Fingerprint`s are equal
899 /// (since the numerical `ExpnId` value is not considered by the `HashStable`
902 /// The `disambiguator` field is set by `update_disambiguator` when two distinct
903 /// `ExpnId`s would end up with the same `Fingerprint`. Since `ExpnData` includes
904 /// a `krate` field, this value only needs to be unique within a single crate.
907 // --- The part specific to the macro/desugaring definition.
908 // --- It may be reasonable to share this part between expansions with the same definition,
909 // --- but such sharing is known to bring some minor inconveniences without also bringing
910 // --- noticeable perf improvements (PR #62898).
911 /// The span of the macro definition (possibly dummy).
912 /// This span serves only informational purpose and is not used for resolution.
914 /// List of `#[unstable]`/feature-gated features that the macro is allowed to use
915 /// internally without forcing the whole crate to opt-in
917 pub allow_internal_unstable: Option<Lrc<[Symbol]>>,
918 /// Whether the macro is allowed to use `unsafe` internally
919 /// even if the user crate has `#![forbid(unsafe_code)]`.
920 pub allow_internal_unsafe: bool,
921 /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`)
922 /// for a given macro.
923 pub local_inner_macros: bool,
924 /// Edition of the crate in which the macro is defined.
925 pub edition: Edition,
926 /// The `DefId` of the macro being invoked,
927 /// if this `ExpnData` corresponds to a macro invocation
928 pub macro_def_id: Option<DefId>,
929 /// The normal module (`mod`) in which the expanded macro was defined.
930 pub parent_module: Option<DefId>,
933 // These would require special handling of `orig_id`.
934 impl !PartialEq for ExpnData {}
935 impl !Hash for ExpnData {}
943 allow_internal_unstable: Option<Lrc<[Symbol]>>,
944 allow_internal_unsafe: bool,
945 local_inner_macros: bool,
947 macro_def_id: Option<DefId>,
948 parent_module: Option<DefId>,
955 allow_internal_unstable,
956 allow_internal_unsafe,
967 /// Constructs expansion data with default properties.
972 macro_def_id: Option<DefId>,
973 parent_module: Option<DefId>,
977 parent: ExpnId::root(),
980 allow_internal_unstable: None,
981 allow_internal_unsafe: false,
982 local_inner_macros: false,
992 pub fn allow_unstable(
996 allow_internal_unstable: Lrc<[Symbol]>,
997 macro_def_id: Option<DefId>,
998 parent_module: Option<DefId>,
1001 allow_internal_unstable: Some(allow_internal_unstable),
1002 ..ExpnData::default(kind, call_site, edition, macro_def_id, parent_module)
1007 pub fn is_root(&self) -> bool {
1008 matches!(self.kind, ExpnKind::Root)
1012 fn hash_expn(&self, ctx: &mut impl HashStableContext) -> u64 {
1013 let mut hasher = StableHasher::new();
1014 self.hash_stable(ctx, &mut hasher);
1020 #[derive(Clone, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
1022 /// No expansion, aka root expansion. Only `ExpnId::root()` has this kind.
1024 /// Expansion produced by a macro.
1025 Macro(MacroKind, Symbol),
1026 /// Transform done by the compiler on the AST.
1028 /// Desugaring done by the compiler during HIR lowering.
1029 Desugaring(DesugaringKind),
1035 pub fn descr(&self) -> String {
1037 ExpnKind::Root => kw::PathRoot.to_string(),
1038 ExpnKind::Macro(macro_kind, name) => match macro_kind {
1039 MacroKind::Bang => format!("{}!", name),
1040 MacroKind::Attr => format!("#[{}]", name),
1041 MacroKind::Derive => format!("#[derive({})]", name),
1043 ExpnKind::AstPass(kind) => kind.descr().to_string(),
1044 ExpnKind::Desugaring(kind) => format!("desugaring of {}", kind.descr()),
1045 ExpnKind::Inlined => "inlined source".to_string(),
1050 /// The kind of macro invocation or definition.
1051 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
1052 #[derive(HashStable_Generic)]
1053 pub enum MacroKind {
1054 /// A bang macro `foo!()`.
1056 /// An attribute macro `#[foo]`.
1058 /// A derive macro `#[derive(Foo)]`
1063 pub fn descr(self) -> &'static str {
1065 MacroKind::Bang => "macro",
1066 MacroKind::Attr => "attribute macro",
1067 MacroKind::Derive => "derive macro",
1071 pub fn descr_expected(self) -> &'static str {
1073 MacroKind::Attr => "attribute",
1078 pub fn article(self) -> &'static str {
1080 MacroKind::Attr => "an",
1086 /// The kind of AST transform.
1087 #[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
1095 fn descr(self) -> &'static str {
1097 AstPass::StdImports => "standard library imports",
1098 AstPass::TestHarness => "test harness",
1099 AstPass::ProcMacroHarness => "proc macro harness",
1104 /// The kind of compiler desugaring.
1105 #[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
1106 pub enum DesugaringKind {
1107 /// We desugar `if c { i } else { e }` to `match $ExprKind::Use(c) { true => i, _ => e }`.
1108 /// However, we do not want to blame `c` for unreachability but rather say that `i`
1109 /// is unreachable. This desugaring kind allows us to avoid blaming `c`.
1110 /// This also applies to `while` loops.
1114 /// Desugaring of an `impl Trait` in return type position
1115 /// to an `type Foo = impl Trait;` and replacing the
1116 /// `impl Trait` with `Foo`.
1120 ForLoop(ForLoopLoc),
1123 /// A location in the desugaring of a `for` loop
1124 #[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
1125 pub enum ForLoopLoc {
1130 impl DesugaringKind {
1131 /// The description wording should combine well with "desugaring of {}".
1132 fn descr(self) -> &'static str {
1134 DesugaringKind::CondTemporary => "`if` or `while` condition",
1135 DesugaringKind::Async => "`async` block or function",
1136 DesugaringKind::Await => "`await` expression",
1137 DesugaringKind::QuestionMark => "operator `?`",
1138 DesugaringKind::TryBlock => "`try` block",
1139 DesugaringKind::OpaqueTy => "`impl Trait`",
1140 DesugaringKind::ForLoop(_) => "`for` loop",
1146 pub struct HygieneEncodeContext {
1147 /// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
1148 /// This is `None` after we finish encoding `SyntaxContexts`, to ensure
1149 /// that we don't accidentally try to encode any more `SyntaxContexts`
1150 serialized_ctxts: Lock<FxHashSet<SyntaxContext>>,
1151 /// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
1152 /// in the most recent 'round' of serializnig. Serializing `SyntaxContextData`
1153 /// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
1154 /// until we reach a fixed point.
1155 latest_ctxts: Lock<FxHashSet<SyntaxContext>>,
1157 serialized_expns: Lock<FxHashSet<ExpnId>>,
1159 latest_expns: Lock<FxHashSet<ExpnId>>,
1162 impl HygieneEncodeContext {
1163 /// Record the fact that we need to serialize the corresponding `ExpnData`.
1164 pub fn schedule_expn_data_for_encoding(&self, expn: ExpnId) {
1165 if !self.serialized_expns.lock().contains(&expn) {
1166 self.latest_expns.lock().insert(expn);
1170 pub fn encode<T, R>(
1173 mut encode_ctxt: impl FnMut(&mut T, u32, &SyntaxContextData) -> Result<(), R>,
1174 mut encode_expn: impl FnMut(&mut T, ExpnId, ExpnData, ExpnHash) -> Result<(), R>,
1175 ) -> Result<(), R> {
1176 // When we serialize a `SyntaxContextData`, we may end up serializing
1177 // a `SyntaxContext` that we haven't seen before
1178 while !self.latest_ctxts.lock().is_empty() || !self.latest_expns.lock().is_empty() {
1180 "encode_hygiene: Serializing a round of {:?} SyntaxContextDatas: {:?}",
1181 self.latest_ctxts.lock().len(),
1185 // Consume the current round of SyntaxContexts.
1186 // Drop the lock() temporary early
1187 let latest_ctxts = { std::mem::take(&mut *self.latest_ctxts.lock()) };
1189 // It's fine to iterate over a HashMap, because the serialization
1190 // of the table that we insert data into doesn't depend on insertion
1192 for_all_ctxts_in(latest_ctxts.into_iter(), |index, ctxt, data| {
1193 if self.serialized_ctxts.lock().insert(ctxt) {
1194 encode_ctxt(encoder, index, data)?;
1199 let latest_expns = { std::mem::take(&mut *self.latest_expns.lock()) };
1201 for_all_expns_in(latest_expns.into_iter(), |expn, data, hash| {
1202 if self.serialized_expns.lock().insert(expn) {
1203 encode_expn(encoder, expn, data, hash)?;
1208 debug!("encode_hygiene: Done serializing SyntaxContextData");
1214 /// Additional information used to assist in decoding hygiene data
1215 pub struct HygieneDecodeContext {
1216 // Maps serialized `SyntaxContext` ids to a `SyntaxContext` in the current
1217 // global `HygieneData`. When we deserialize a `SyntaxContext`, we need to create
1218 // a new id in the global `HygieneData`. This map tracks the ID we end up picking,
1219 // so that multiple occurrences of the same serialized id are decoded to the same
1221 remapped_ctxts: Lock<Vec<Option<SyntaxContext>>>,
1224 /// Register an expansion which has been decoded from the on-disk-cache for the local crate.
1225 pub fn register_local_expn_id(mut data: ExpnData, hash: ExpnHash) -> ExpnId {
1226 HygieneData::with(|hygiene_data| {
1227 // If we just deserialized an `ExpnData` owned by
1228 // the local crate, its `orig_id` will be stale,
1229 // so we need to update it to its own value.
1230 // This only happens when we deserialize the incremental cache,
1231 // since a crate will never decode its own metadata.
1232 let expn_id = hygiene_data.local_expn_data.next_index();
1233 data.orig_id = Some(expn_id.as_u32());
1234 hygiene_data.local_expn_data.push(Some(data));
1235 let _eid = hygiene_data.local_expn_hashes.push(hash);
1236 debug_assert_eq!(expn_id, _eid);
1238 let expn_id = expn_id.to_expn_id();
1240 let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
1241 debug_assert!(_old_id.is_none());
1246 /// Register an expansion which has been decoded from the metadata of a foreign crate.
1247 pub fn register_expn_id(data: ExpnData, hash: ExpnHash) -> ExpnId {
1249 ExpnId { krate: data.krate, local_id: ExpnIndex::from_u32(data.orig_id.unwrap()) };
1250 HygieneData::with(|hygiene_data| {
1251 let _old_data = hygiene_data.foreign_expn_data.insert(expn_id, data);
1252 debug_assert!(_old_data.is_none());
1253 let _old_hash = hygiene_data.foreign_expn_hashes.insert(expn_id, hash);
1254 debug_assert!(_old_hash.is_none());
1255 let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
1256 debug_assert!(_old_id.is_none());
1261 /// Decode an expansion from the metadata of a foreign crate.
1262 pub fn decode_expn_id(
1265 decode_data: impl FnOnce(ExpnId) -> (ExpnData, ExpnHash),
1268 debug!("decode_expn_id: deserialized root");
1269 return ExpnId::root();
1272 let index = ExpnIndex::from_u32(index);
1274 // This function is used to decode metadata, so it cannot decode information about LOCAL_CRATE.
1275 debug_assert_ne!(krate, LOCAL_CRATE);
1276 let expn_id = ExpnId { krate, local_id: index };
1278 // Fast path if the expansion has already been decoded.
1279 if HygieneData::with(|hygiene_data| hygiene_data.foreign_expn_data.contains_key(&expn_id)) {
1283 // Don't decode the data inside `HygieneData::with`, since we need to recursively decode
1285 let (expn_data, hash) = decode_data(expn_id);
1286 debug_assert_eq!(krate, expn_data.krate);
1287 debug_assert_eq!(Some(index.as_u32()), expn_data.orig_id);
1289 register_expn_id(expn_data, hash)
1292 // Decodes `SyntaxContext`, using the provided `HygieneDecodeContext`
1293 // to track which `SyntaxContext`s we have already decoded.
1294 // The provided closure will be invoked to deserialize a `SyntaxContextData`
1295 // if we haven't already seen the id of the `SyntaxContext` we are deserializing.
1296 pub fn decode_syntax_context<
1298 F: FnOnce(&mut D, u32) -> Result<SyntaxContextData, D::Error>,
1301 context: &HygieneDecodeContext,
1303 ) -> Result<SyntaxContext, D::Error> {
1304 let raw_id: u32 = Decodable::decode(d)?;
1306 debug!("decode_syntax_context: deserialized root");
1307 // The root is special
1308 return Ok(SyntaxContext::root());
1311 let outer_ctxts = &context.remapped_ctxts;
1313 // Ensure that the lock() temporary is dropped early
1315 if let Some(ctxt) = outer_ctxts.lock().get(raw_id as usize).copied().flatten() {
1320 // Allocate and store SyntaxContext id *before* calling the decoder function,
1321 // as the SyntaxContextData may reference itself.
1322 let new_ctxt = HygieneData::with(|hygiene_data| {
1323 let new_ctxt = SyntaxContext(hygiene_data.syntax_context_data.len() as u32);
1324 // Push a dummy SyntaxContextData to ensure that nobody else can get the
1325 // same ID as us. This will be overwritten after call `decode_Data`
1326 hygiene_data.syntax_context_data.push(SyntaxContextData {
1327 outer_expn: ExpnId::root(),
1328 outer_transparency: Transparency::Transparent,
1329 parent: SyntaxContext::root(),
1330 opaque: SyntaxContext::root(),
1331 opaque_and_semitransparent: SyntaxContext::root(),
1332 dollar_crate_name: kw::Empty,
1334 let mut ctxts = outer_ctxts.lock();
1335 let new_len = raw_id as usize + 1;
1336 if ctxts.len() < new_len {
1337 ctxts.resize(new_len, None);
1339 ctxts[raw_id as usize] = Some(new_ctxt);
1344 // Don't try to decode data while holding the lock, since we need to
1345 // be able to recursively decode a SyntaxContext
1346 let mut ctxt_data = decode_data(d, raw_id)?;
1347 // Reset `dollar_crate_name` so that it will be updated by `update_dollar_crate_names`
1348 // We don't care what the encoding crate set this to - we want to resolve it
1349 // from the perspective of the current compilation session
1350 ctxt_data.dollar_crate_name = kw::DollarCrate;
1352 // Overwrite the dummy data with our decoded SyntaxContextData
1353 HygieneData::with(|hygiene_data| {
1354 let dummy = std::mem::replace(
1355 &mut hygiene_data.syntax_context_data[new_ctxt.as_u32() as usize],
1358 // Make sure nothing weird happening while `decode_data` was running
1359 assert_eq!(dummy.dollar_crate_name, kw::Empty);
1365 fn for_all_ctxts_in<E, F: FnMut(u32, SyntaxContext, &SyntaxContextData) -> Result<(), E>>(
1366 ctxts: impl Iterator<Item = SyntaxContext>,
1368 ) -> Result<(), E> {
1369 let all_data: Vec<_> = HygieneData::with(|data| {
1370 ctxts.map(|ctxt| (ctxt, data.syntax_context_data[ctxt.0 as usize].clone())).collect()
1372 for (ctxt, data) in all_data.into_iter() {
1373 f(ctxt.0, ctxt, &data)?;
1378 fn for_all_expns_in<E>(
1379 expns: impl Iterator<Item = ExpnId>,
1380 mut f: impl FnMut(ExpnId, ExpnData, ExpnHash) -> Result<(), E>,
1381 ) -> Result<(), E> {
1382 let all_data: Vec<_> = HygieneData::with(|data| {
1384 .map(|expn| (expn, data.expn_data(expn).clone(), data.expn_hash(expn).clone()))
1387 for (expn, data, hash) in all_data.into_iter() {
1388 f(expn, data, hash)?;
1393 impl<E: Encoder> Encodable<E> for LocalExpnId {
1394 fn encode(&self, e: &mut E) -> Result<(), E::Error> {
1395 self.to_expn_id().encode(e)
1399 impl<E: Encoder> Encodable<E> for ExpnId {
1400 default fn encode(&self, _: &mut E) -> Result<(), E::Error> {
1401 panic!("cannot encode `ExpnId` with `{}`", std::any::type_name::<E>());
1405 impl<D: Decoder> Decodable<D> for LocalExpnId {
1406 fn decode(d: &mut D) -> Result<Self, D::Error> {
1407 ExpnId::decode(d).map(ExpnId::expect_local)
1411 impl<D: Decoder> Decodable<D> for ExpnId {
1412 default fn decode(_: &mut D) -> Result<Self, D::Error> {
1413 panic!("cannot decode `ExpnId` with `{}`", std::any::type_name::<D>());
1417 pub fn raw_encode_syntax_context<E: Encoder>(
1418 ctxt: SyntaxContext,
1419 context: &HygieneEncodeContext,
1421 ) -> Result<(), E::Error> {
1422 if !context.serialized_ctxts.lock().contains(&ctxt) {
1423 context.latest_ctxts.lock().insert(ctxt);
1428 impl<E: Encoder> Encodable<E> for SyntaxContext {
1429 default fn encode(&self, _: &mut E) -> Result<(), E::Error> {
1430 panic!("cannot encode `SyntaxContext` with `{}`", std::any::type_name::<E>());
1434 impl<D: Decoder> Decodable<D> for SyntaxContext {
1435 default fn decode(_: &mut D) -> Result<Self, D::Error> {
1436 panic!("cannot decode `SyntaxContext` with `{}`", std::any::type_name::<D>());
1440 /// Updates the `disambiguator` field of the corresponding `ExpnData`
1441 /// such that the `Fingerprint` of the `ExpnData` does not collide with
1442 /// any other `ExpnIds`.
1444 /// This method is called only when an `ExpnData` is first associated
1445 /// with an `ExpnId` (when the `ExpnId` is initially constructed, or via
1446 /// `set_expn_data`). It is *not* called for foreign `ExpnId`s deserialized
1447 /// from another crate's metadata - since `ExpnData` includes a `krate` field,
1448 /// collisions are only possible between `ExpnId`s within the same crate.
1449 fn update_disambiguator(expn_id: LocalExpnId, mut ctx: impl HashStableContext) {
1450 let mut expn_data = expn_id.expn_data();
1451 // This disambiguator should not have been set yet.
1453 expn_data.disambiguator, 0,
1454 "Already set disambiguator for ExpnData: {:?}",
1457 let mut expn_hash = expn_data.hash_expn(&mut ctx);
1459 let disambiguator = HygieneData::with(|data| {
1460 // If this is the first ExpnData with a given hash, then keep our
1461 // disambiguator at 0 (the default u32 value)
1462 let disambig = data.expn_data_disambiguators.entry(expn_hash).or_default();
1463 let disambiguator = *disambig;
1468 if disambiguator != 0 {
1469 debug!("Set disambiguator for {:?} (hash {:?})", expn_id, expn_hash);
1470 debug!("expn_data = {:?}", expn_data);
1472 expn_data.disambiguator = disambiguator;
1473 expn_hash = expn_data.hash_expn(&mut ctx);
1475 // Verify that the new disambiguator makes the hash unique
1476 #[cfg(debug_assertions)]
1477 HygieneData::with(|data| {
1479 data.expn_data_disambiguators.get(&expn_hash),
1481 "Hash collision after disambiguator update!",
1487 ExpnHash::new(ctx.def_path_hash(LOCAL_CRATE.as_def_id()).stable_crate_id(), expn_hash);
1488 HygieneData::with(|data| {
1489 data.local_expn_data[expn_id].as_mut().unwrap().disambiguator = disambiguator;
1490 debug_assert_eq!(data.local_expn_hashes[expn_id].0, Fingerprint::ZERO);
1491 data.local_expn_hashes[expn_id] = expn_hash;
1492 let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, expn_id.to_expn_id());
1493 debug_assert!(_old_id.is_none());
1497 impl<CTX: HashStableContext> HashStable<CTX> for SyntaxContext {
1498 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1499 const TAG_EXPANSION: u8 = 0;
1500 const TAG_NO_EXPANSION: u8 = 1;
1502 if *self == SyntaxContext::root() {
1503 TAG_NO_EXPANSION.hash_stable(ctx, hasher);
1505 TAG_EXPANSION.hash_stable(ctx, hasher);
1506 let (expn_id, transparency) = self.outer_mark();
1507 expn_id.hash_stable(ctx, hasher);
1508 transparency.hash_stable(ctx, hasher);
1513 impl<CTX: HashStableContext> HashStable<CTX> for ExpnId {
1514 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1515 let hash = if *self == ExpnId::root() {
1516 // Avoid fetching TLS storage for a trivial often-used value.
1522 hash.hash_stable(ctx, hasher);