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+//! Machinery for hygienic macros.
+//!
+//! Inspired by Matthew Flatt et al., “Macros That Work Together: Compile-Time Bindings, Partial
+//! Expansion, and Definition Contexts,” *Journal of Functional Programming* 22, no. 2
+//! (March 1, 2012): 181–216, <https://doi.org/10.1017/S0956796812000093>.
+
+// Hygiene data is stored in a global variable and accessed via TLS, which
+// means that accesses are somewhat expensive. (`HygieneData::with`
+// encapsulates a single access.) Therefore, on hot code paths it is worth
+// ensuring that multiple HygieneData accesses are combined into a single
+// `HygieneData::with`.
+//
+// This explains why `HygieneData`, `SyntaxContext` and `ExpnId` have interfaces
+// with a certain amount of redundancy in them. For example,
+// `SyntaxContext::outer_expn_data` combines `SyntaxContext::outer` and
+// `ExpnId::expn_data` so that two `HygieneData` accesses can be performed within
+// a single `HygieneData::with` call.
+//
+// It also explains why many functions appear in `HygieneData` and again in
+// `SyntaxContext` or `ExpnId`. For example, `HygieneData::outer` and
+// `SyntaxContext::outer` do the same thing, but the former is for use within a
+// `HygieneData::with` call while the latter is for use outside such a call.
+// When modifying this file it is important to understand this distinction,
+// because getting it wrong can lead to nested `HygieneData::with` calls that
+// trigger runtime aborts. (Fortunately these are obvious and easy to fix.)
+
+use crate::edition::Edition;
+use crate::symbol::{kw, sym, Symbol};
+use crate::with_session_globals;
+use crate::{HashStableContext, Span, DUMMY_SP};
+
+use crate::def_id::{CrateNum, DefId, StableCrateId, CRATE_DEF_ID, LOCAL_CRATE};
+use rustc_data_structures::fingerprint::Fingerprint;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::stable_hasher::HashingControls;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_data_structures::sync::{Lock, Lrc};
+use rustc_data_structures::unhash::UnhashMap;
+use rustc_index::vec::IndexVec;
+use rustc_macros::HashStable_Generic;
+use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
+use std::fmt;
+use std::hash::Hash;
+use tracing::*;
+
+/// A `SyntaxContext` represents a chain of pairs `(ExpnId, Transparency)` named "marks".
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct SyntaxContext(u32);
+
+#[derive(Debug, Encodable, Decodable, Clone)]
+pub struct SyntaxContextData {
+ outer_expn: ExpnId,
+ outer_transparency: Transparency,
+ parent: SyntaxContext,
+ /// This context, but with all transparent and semi-transparent expansions filtered away.
+ opaque: SyntaxContext,
+ /// This context, but with all transparent expansions filtered away.
+ opaque_and_semitransparent: SyntaxContext,
+ /// Name of the crate to which `$crate` with this context would resolve.
+ dollar_crate_name: Symbol,
+}
+
+rustc_index::newtype_index! {
+ /// A unique ID associated with a macro invocation and expansion.
+ pub struct ExpnIndex {
+ ENCODABLE = custom
+ }
+}
+
+/// A unique ID associated with a macro invocation and expansion.
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ExpnId {
+ pub krate: CrateNum,
+ pub local_id: ExpnIndex,
+}
+
+impl fmt::Debug for ExpnId {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ // Generate crate_::{{expn_}}.
+ write!(f, "{:?}::{{{{expn{}}}}}", self.krate, self.local_id.private)
+ }
+}
+
+rustc_index::newtype_index! {
+ /// A unique ID associated with a macro invocation and expansion.
+ pub struct LocalExpnId {
+ ENCODABLE = custom
+ ORD_IMPL = custom
+ DEBUG_FORMAT = "expn{}"
+ }
+}
+
+// To ensure correctness of incremental compilation,
+// `LocalExpnId` must not implement `Ord` or `PartialOrd`.
+// See https://github.com/rust-lang/rust/issues/90317.
+impl !Ord for LocalExpnId {}
+impl !PartialOrd for LocalExpnId {}
+
+/// Assert that the provided `HashStableContext` is configured with the 'default'
+/// `HashingControls`. We should always have bailed out before getting to here
+/// with a non-default mode. With this check in place, we can avoid the need
+/// to maintain separate versions of `ExpnData` hashes for each permutation
+/// of `HashingControls` settings.
+fn assert_default_hashing_controls<CTX: HashStableContext>(ctx: &CTX, msg: &str) {
+ match ctx.hashing_controls() {
+ // Note that we require that `hash_spans` be set according to the global
+ // `-Z incremental-ignore-spans` option. Normally, this option is disabled,
+ // which will cause us to require that this method always be called with `Span` hashing
+ // enabled.
+ HashingControls { hash_spans }
+ if hash_spans == !ctx.unstable_opts_incremental_ignore_spans() => {}
+ other => panic!("Attempted hashing of {msg} with non-default HashingControls: {:?}", other),
+ }
+}
+
+/// A unique hash value associated to an expansion.
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, Encodable, Decodable, HashStable_Generic)]
+pub struct ExpnHash(Fingerprint);
+
+impl ExpnHash {
+ /// Returns the [StableCrateId] identifying the crate this [ExpnHash]
+ /// originates from.
+ #[inline]
+ pub fn stable_crate_id(self) -> StableCrateId {
+ StableCrateId(self.0.as_value().0)
+ }
+
+ /// Returns the crate-local part of the [ExpnHash].
+ ///
+ /// Used for tests.
+ #[inline]
+ pub fn local_hash(self) -> u64 {
+ self.0.as_value().1
+ }
+
+ #[inline]
+ pub fn is_root(self) -> bool {
+ self.0 == Fingerprint::ZERO
+ }
+
+ /// Builds a new [ExpnHash] with the given [StableCrateId] and
+ /// `local_hash`, where `local_hash` must be unique within its crate.
+ fn new(stable_crate_id: StableCrateId, local_hash: u64) -> ExpnHash {
+ ExpnHash(Fingerprint::new(stable_crate_id.0, local_hash))
+ }
+}
+
+/// A property of a macro expansion that determines how identifiers
+/// produced by that expansion are resolved.
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Hash, Debug, Encodable, Decodable)]
+#[derive(HashStable_Generic)]
+pub enum Transparency {
+ /// Identifier produced by a transparent expansion is always resolved at call-site.
+ /// Call-site spans in procedural macros, hygiene opt-out in `macro` should use this.
+ Transparent,
+ /// Identifier produced by a semi-transparent expansion may be resolved
+ /// either at call-site or at definition-site.
+ /// If it's a local variable, label or `$crate` then it's resolved at def-site.
+ /// Otherwise it's resolved at call-site.
+ /// `macro_rules` macros behave like this, built-in macros currently behave like this too,
+ /// but that's an implementation detail.
+ SemiTransparent,
+ /// Identifier produced by an opaque expansion is always resolved at definition-site.
+ /// Def-site spans in procedural macros, identifiers from `macro` by default use this.
+ Opaque,
+}
+
+impl LocalExpnId {
+ /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
+ pub const ROOT: LocalExpnId = LocalExpnId::from_u32(0);
+
+ #[inline]
+ pub fn from_raw(idx: ExpnIndex) -> LocalExpnId {
+ LocalExpnId::from_u32(idx.as_u32())
+ }
+
+ #[inline]
+ pub fn as_raw(self) -> ExpnIndex {
+ ExpnIndex::from_u32(self.as_u32())
+ }
+
+ pub fn fresh_empty() -> LocalExpnId {
+ HygieneData::with(|data| {
+ let expn_id = data.local_expn_data.push(None);
+ let _eid = data.local_expn_hashes.push(ExpnHash(Fingerprint::ZERO));
+ debug_assert_eq!(expn_id, _eid);
+ expn_id
+ })
+ }
+
+ pub fn fresh(mut expn_data: ExpnData, ctx: impl HashStableContext) -> LocalExpnId {
+ debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
+ let expn_hash = update_disambiguator(&mut expn_data, ctx);
+ HygieneData::with(|data| {
+ let expn_id = data.local_expn_data.push(Some(expn_data));
+ let _eid = data.local_expn_hashes.push(expn_hash);
+ debug_assert_eq!(expn_id, _eid);
+ let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, expn_id.to_expn_id());
+ debug_assert!(_old_id.is_none());
+ expn_id
+ })
+ }
+
+ #[inline]
+ pub fn expn_hash(self) -> ExpnHash {
+ HygieneData::with(|data| data.local_expn_hash(self))
+ }
+
+ #[inline]
+ pub fn expn_data(self) -> ExpnData {
+ HygieneData::with(|data| data.local_expn_data(self).clone())
+ }
+
+ #[inline]
+ pub fn to_expn_id(self) -> ExpnId {
+ ExpnId { krate: LOCAL_CRATE, local_id: self.as_raw() }
+ }
+
+ #[inline]
+ pub fn set_expn_data(self, mut expn_data: ExpnData, ctx: impl HashStableContext) {
+ debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
+ let expn_hash = update_disambiguator(&mut expn_data, ctx);
+ HygieneData::with(|data| {
+ let old_expn_data = &mut data.local_expn_data[self];
+ assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
+ *old_expn_data = Some(expn_data);
+ debug_assert_eq!(data.local_expn_hashes[self].0, Fingerprint::ZERO);
+ data.local_expn_hashes[self] = expn_hash;
+ let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, self.to_expn_id());
+ debug_assert!(_old_id.is_none());
+ });
+ }
+
+ #[inline]
+ pub fn is_descendant_of(self, ancestor: LocalExpnId) -> bool {
+ self.to_expn_id().is_descendant_of(ancestor.to_expn_id())
+ }
+
+ /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
+ /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
+ #[inline]
+ pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
+ self.to_expn_id().outer_expn_is_descendant_of(ctxt)
+ }
+
+ /// Returns span for the macro which originally caused this expansion to happen.
+ ///
+ /// Stops backtracing at include! boundary.
+ #[inline]
+ pub fn expansion_cause(self) -> Option<Span> {
+ self.to_expn_id().expansion_cause()
+ }
+
+ #[inline]
+ #[track_caller]
+ pub fn parent(self) -> LocalExpnId {
+ self.expn_data().parent.as_local().unwrap()
+ }
+}
+
+impl ExpnId {
+ /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
+ /// Invariant: we do not create any ExpnId with local_id == 0 and krate != 0.
+ pub const fn root() -> ExpnId {
+ ExpnId { krate: LOCAL_CRATE, local_id: ExpnIndex::from_u32(0) }
+ }
+
+ #[inline]
+ pub fn expn_hash(self) -> ExpnHash {
+ HygieneData::with(|data| data.expn_hash(self))
+ }
+
+ #[inline]
+ pub fn from_hash(hash: ExpnHash) -> Option<ExpnId> {
+ HygieneData::with(|data| data.expn_hash_to_expn_id.get(&hash).copied())
+ }
+
+ #[inline]
+ pub fn as_local(self) -> Option<LocalExpnId> {
+ if self.krate == LOCAL_CRATE { Some(LocalExpnId::from_raw(self.local_id)) } else { None }
+ }
+
+ #[inline]
+ #[track_caller]
+ pub fn expect_local(self) -> LocalExpnId {
+ self.as_local().unwrap()
+ }
+
+ #[inline]
+ pub fn expn_data(self) -> ExpnData {
+ HygieneData::with(|data| data.expn_data(self).clone())
+ }
+
+ #[inline]
+ pub fn is_descendant_of(self, ancestor: ExpnId) -> bool {
+ // a few "fast path" cases to avoid locking HygieneData
+ if ancestor == ExpnId::root() || ancestor == self {
+ return true;
+ }
+ if ancestor.krate != self.krate {
+ return false;
+ }
+ HygieneData::with(|data| data.is_descendant_of(self, ancestor))
+ }
+
+ /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
+ /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
+ pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
+ HygieneData::with(|data| data.is_descendant_of(self, data.outer_expn(ctxt)))
+ }
+
+ /// Returns span for the macro which originally caused this expansion to happen.
+ ///
+ /// Stops backtracing at include! boundary.
+ pub fn expansion_cause(mut self) -> Option<Span> {
+ let mut last_macro = None;
+ loop {
+ let expn_data = self.expn_data();
+ // Stop going up the backtrace once include! is encountered
+ if expn_data.is_root()
+ || expn_data.kind == ExpnKind::Macro(MacroKind::Bang, sym::include)
+ {
+ break;
+ }
+ self = expn_data.call_site.ctxt().outer_expn();
+ last_macro = Some(expn_data.call_site);
+ }
+ last_macro
+ }
+}
+
+#[derive(Debug)]
+pub struct HygieneData {
+ /// Each expansion should have an associated expansion data, but sometimes there's a delay
+ /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
+ /// first and then resolved later), so we use an `Option` here.
+ local_expn_data: IndexVec<LocalExpnId, Option<ExpnData>>,
+ local_expn_hashes: IndexVec<LocalExpnId, ExpnHash>,
+ /// Data and hash information from external crates. We may eventually want to remove these
+ /// maps, and fetch the information directly from the other crate's metadata like DefIds do.
+ foreign_expn_data: FxHashMap<ExpnId, ExpnData>,
+ foreign_expn_hashes: FxHashMap<ExpnId, ExpnHash>,
+ expn_hash_to_expn_id: UnhashMap<ExpnHash, ExpnId>,
+ syntax_context_data: Vec<SyntaxContextData>,
+ syntax_context_map: FxHashMap<(SyntaxContext, ExpnId, Transparency), SyntaxContext>,
+ /// Maps the `local_hash` of an `ExpnData` to the next disambiguator value.
+ /// This is used by `update_disambiguator` to keep track of which `ExpnData`s
+ /// would have collisions without a disambiguator.
+ /// The keys of this map are always computed with `ExpnData.disambiguator`
+ /// set to 0.
+ expn_data_disambiguators: FxHashMap<u64, u32>,
+}
+
+impl HygieneData {
+ pub(crate) fn new(edition: Edition) -> Self {
+ let root_data = ExpnData::default(
+ ExpnKind::Root,
+ DUMMY_SP,
+ edition,
+ Some(CRATE_DEF_ID.to_def_id()),
+ None,
+ );
+
+ HygieneData {
+ local_expn_data: IndexVec::from_elem_n(Some(root_data), 1),
+ local_expn_hashes: IndexVec::from_elem_n(ExpnHash(Fingerprint::ZERO), 1),
+ foreign_expn_data: FxHashMap::default(),
+ foreign_expn_hashes: FxHashMap::default(),
+ expn_hash_to_expn_id: std::iter::once((ExpnHash(Fingerprint::ZERO), ExpnId::root()))
+ .collect(),
+ syntax_context_data: vec![SyntaxContextData {
+ outer_expn: ExpnId::root(),
+ outer_transparency: Transparency::Opaque,
+ parent: SyntaxContext(0),
+ opaque: SyntaxContext(0),
+ opaque_and_semitransparent: SyntaxContext(0),
+ dollar_crate_name: kw::DollarCrate,
+ }],
+ syntax_context_map: FxHashMap::default(),
+ expn_data_disambiguators: FxHashMap::default(),
+ }
+ }
+
+ pub fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
+ with_session_globals(|session_globals| f(&mut *session_globals.hygiene_data.borrow_mut()))
+ }
+
+ #[inline]
+ fn local_expn_hash(&self, expn_id: LocalExpnId) -> ExpnHash {
+ self.local_expn_hashes[expn_id]
+ }
+
+ #[inline]
+ fn expn_hash(&self, expn_id: ExpnId) -> ExpnHash {
+ match expn_id.as_local() {
+ Some(expn_id) => self.local_expn_hashes[expn_id],
+ None => self.foreign_expn_hashes[&expn_id],
+ }
+ }
+
+ fn local_expn_data(&self, expn_id: LocalExpnId) -> &ExpnData {
+ self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
+ }
+
+ fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
+ if let Some(expn_id) = expn_id.as_local() {
+ self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
+ } else {
+ &self.foreign_expn_data[&expn_id]
+ }
+ }
+
+ fn is_descendant_of(&self, mut expn_id: ExpnId, ancestor: ExpnId) -> bool {
+ // a couple "fast path" cases to avoid traversing parents in the loop below
+ if ancestor == ExpnId::root() {
+ return true;
+ }
+ if expn_id.krate != ancestor.krate {
+ return false;
+ }
+ loop {
+ if expn_id == ancestor {
+ return true;
+ }
+ if expn_id == ExpnId::root() {
+ return false;
+ }
+ expn_id = self.expn_data(expn_id).parent;
+ }
+ }
+
+ fn normalize_to_macros_2_0(&self, ctxt: SyntaxContext) -> SyntaxContext {
+ self.syntax_context_data[ctxt.0 as usize].opaque
+ }
+
+ fn normalize_to_macro_rules(&self, ctxt: SyntaxContext) -> SyntaxContext {
+ self.syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent
+ }
+
+ fn outer_expn(&self, ctxt: SyntaxContext) -> ExpnId {
+ self.syntax_context_data[ctxt.0 as usize].outer_expn
+ }
+
+ fn outer_mark(&self, ctxt: SyntaxContext) -> (ExpnId, Transparency) {
+ let data = &self.syntax_context_data[ctxt.0 as usize];
+ (data.outer_expn, data.outer_transparency)
+ }
+
+ fn parent_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext {
+ self.syntax_context_data[ctxt.0 as usize].parent
+ }
+
+ fn remove_mark(&self, ctxt: &mut SyntaxContext) -> (ExpnId, Transparency) {
+ let outer_mark = self.outer_mark(*ctxt);
+ *ctxt = self.parent_ctxt(*ctxt);
+ outer_mark
+ }
+
+ fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
+ let mut marks = Vec::new();
+ while ctxt != SyntaxContext::root() {
+ debug!("marks: getting parent of {:?}", ctxt);
+ marks.push(self.outer_mark(ctxt));
+ ctxt = self.parent_ctxt(ctxt);
+ }
+ marks.reverse();
+ marks
+ }
+
+ fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span {
+ debug!("walk_chain({:?}, {:?})", span, to);
+ debug!("walk_chain: span ctxt = {:?}", span.ctxt());
+ while span.from_expansion() && span.ctxt() != to {
+ let outer_expn = self.outer_expn(span.ctxt());
+ debug!("walk_chain({:?}): outer_expn={:?}", span, outer_expn);
+ let expn_data = self.expn_data(outer_expn);
+ debug!("walk_chain({:?}): expn_data={:?}", span, expn_data);
+ span = expn_data.call_site;
+ }
+ span
+ }
+
+ fn adjust(&self, ctxt: &mut SyntaxContext, expn_id: ExpnId) -> Option<ExpnId> {
+ let mut scope = None;
+ while !self.is_descendant_of(expn_id, self.outer_expn(*ctxt)) {
+ scope = Some(self.remove_mark(ctxt).0);
+ }
+ scope
+ }
+
+ fn apply_mark(
+ &mut self,
+ ctxt: SyntaxContext,
+ expn_id: ExpnId,
+ transparency: Transparency,
+ ) -> SyntaxContext {
+ assert_ne!(expn_id, ExpnId::root());
+ if transparency == Transparency::Opaque {
+ return self.apply_mark_internal(ctxt, expn_id, transparency);
+ }
+
+ let call_site_ctxt = self.expn_data(expn_id).call_site.ctxt();
+ let mut call_site_ctxt = if transparency == Transparency::SemiTransparent {
+ self.normalize_to_macros_2_0(call_site_ctxt)
+ } else {
+ self.normalize_to_macro_rules(call_site_ctxt)
+ };
+
+ if call_site_ctxt == SyntaxContext::root() {
+ return self.apply_mark_internal(ctxt, expn_id, transparency);
+ }
+
+ // Otherwise, `expn_id` is a macros 1.0 definition and the call site is in a
+ // macros 2.0 expansion, i.e., a macros 1.0 invocation is in a macros 2.0 definition.
+ //
+ // In this case, the tokens from the macros 1.0 definition inherit the hygiene
+ // at their invocation. That is, we pretend that the macros 1.0 definition
+ // was defined at its invocation (i.e., inside the macros 2.0 definition)
+ // so that the macros 2.0 definition remains hygienic.
+ //
+ // See the example at `test/ui/hygiene/legacy_interaction.rs`.
+ for (expn_id, transparency) in self.marks(ctxt) {
+ call_site_ctxt = self.apply_mark_internal(call_site_ctxt, expn_id, transparency);
+ }
+ self.apply_mark_internal(call_site_ctxt, expn_id, transparency)
+ }
+
+ fn apply_mark_internal(
+ &mut self,
+ ctxt: SyntaxContext,
+ expn_id: ExpnId,
+ transparency: Transparency,
+ ) -> SyntaxContext {
+ let syntax_context_data = &mut self.syntax_context_data;
+ let mut opaque = syntax_context_data[ctxt.0 as usize].opaque;
+ let mut opaque_and_semitransparent =
+ syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent;
+
+ if transparency >= Transparency::Opaque {
+ let parent = opaque;
+ opaque = *self
+ .syntax_context_map
+ .entry((parent, expn_id, transparency))
+ .or_insert_with(|| {
+ let new_opaque = SyntaxContext(syntax_context_data.len() as u32);
+ syntax_context_data.push(SyntaxContextData {
+ outer_expn: expn_id,
+ outer_transparency: transparency,
+ parent,
+ opaque: new_opaque,
+ opaque_and_semitransparent: new_opaque,
+ dollar_crate_name: kw::DollarCrate,
+ });
+ new_opaque
+ });
+ }
+
+ if transparency >= Transparency::SemiTransparent {
+ let parent = opaque_and_semitransparent;
+ opaque_and_semitransparent = *self
+ .syntax_context_map
+ .entry((parent, expn_id, transparency))
+ .or_insert_with(|| {
+ let new_opaque_and_semitransparent =
+ SyntaxContext(syntax_context_data.len() as u32);
+ syntax_context_data.push(SyntaxContextData {
+ outer_expn: expn_id,
+ outer_transparency: transparency,
+ parent,
+ opaque,
+ opaque_and_semitransparent: new_opaque_and_semitransparent,
+ dollar_crate_name: kw::DollarCrate,
+ });
+ new_opaque_and_semitransparent
+ });
+ }
+
+ let parent = ctxt;
+ *self.syntax_context_map.entry((parent, expn_id, transparency)).or_insert_with(|| {
+ let new_opaque_and_semitransparent_and_transparent =
+ SyntaxContext(syntax_context_data.len() as u32);
+ syntax_context_data.push(SyntaxContextData {
+ outer_expn: expn_id,
+ outer_transparency: transparency,
+ parent,
+ opaque,
+ opaque_and_semitransparent,
+ dollar_crate_name: kw::DollarCrate,
+ });
+ new_opaque_and_semitransparent_and_transparent
+ })
+ }
+}
+
+pub fn clear_syntax_context_map() {
+ HygieneData::with(|data| data.syntax_context_map = FxHashMap::default());
+}
+
+pub fn walk_chain(span: Span, to: SyntaxContext) -> Span {
+ HygieneData::with(|data| data.walk_chain(span, to))
+}
+
+pub fn update_dollar_crate_names(mut get_name: impl FnMut(SyntaxContext) -> Symbol) {
+ // The new contexts that need updating are at the end of the list and have `$crate` as a name.
+ let (len, to_update) = HygieneData::with(|data| {
+ (
+ data.syntax_context_data.len(),
+ data.syntax_context_data
+ .iter()
+ .rev()
+ .take_while(|scdata| scdata.dollar_crate_name == kw::DollarCrate)
+ .count(),
+ )
+ });
+ // The callback must be called from outside of the `HygieneData` lock,
+ // since it will try to acquire it too.
+ let range_to_update = len - to_update..len;
+ let names: Vec<_> =
+ range_to_update.clone().map(|idx| get_name(SyntaxContext::from_u32(idx as u32))).collect();
+ HygieneData::with(|data| {
+ range_to_update.zip(names).for_each(|(idx, name)| {
+ data.syntax_context_data[idx].dollar_crate_name = name;
+ })
+ })
+}
+
+pub fn debug_hygiene_data(verbose: bool) -> String {
+ HygieneData::with(|data| {
+ if verbose {
+ format!("{:#?}", data)
+ } else {
+ let mut s = String::from("Expansions:");
+ let mut debug_expn_data = |(id, expn_data): (&ExpnId, &ExpnData)| {
+ s.push_str(&format!(
+ "\n{:?}: parent: {:?}, call_site_ctxt: {:?}, def_site_ctxt: {:?}, kind: {:?}",
+ id,
+ expn_data.parent,
+ expn_data.call_site.ctxt(),
+ expn_data.def_site.ctxt(),
+ expn_data.kind,
+ ))
+ };
+ data.local_expn_data.iter_enumerated().for_each(|(id, expn_data)| {
+ let expn_data = expn_data.as_ref().expect("no expansion data for an expansion ID");
+ debug_expn_data((&id.to_expn_id(), expn_data))
+ });
+
+ // Sort the hash map for more reproducible output.
+ // Because of this, it is fine to rely on the unstable iteration order of the map.
+ #[allow(rustc::potential_query_instability)]
+ let mut foreign_expn_data: Vec<_> = data.foreign_expn_data.iter().collect();
+ foreign_expn_data.sort_by_key(|(id, _)| (id.krate, id.local_id));
+ foreign_expn_data.into_iter().for_each(debug_expn_data);
+ s.push_str("\n\nSyntaxContexts:");
+ data.syntax_context_data.iter().enumerate().for_each(|(id, ctxt)| {
+ s.push_str(&format!(
+ "\n#{}: parent: {:?}, outer_mark: ({:?}, {:?})",
+ id, ctxt.parent, ctxt.outer_expn, ctxt.outer_transparency,
+ ));
+ });
+ s
+ }
+ })
+}
+
+impl SyntaxContext {
+ #[inline]
+ pub const fn root() -> Self {
+ SyntaxContext(0)
+ }
+
+ #[inline]
+ pub(crate) fn as_u32(self) -> u32 {
+ self.0
+ }
+
+ #[inline]
+ pub(crate) fn from_u32(raw: u32) -> SyntaxContext {
+ SyntaxContext(raw)
+ }
+
+ /// Extend a syntax context with a given expansion and transparency.
+ pub(crate) fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext {
+ HygieneData::with(|data| data.apply_mark(self, expn_id, transparency))
+ }
+
+ /// Pulls a single mark off of the syntax context. This effectively moves the
+ /// context up one macro definition level. That is, if we have a nested macro
+ /// definition as follows:
+ ///
+ /// ```ignore (illustrative)
+ /// macro_rules! f {
+ /// macro_rules! g {
+ /// ...
+ /// }
+ /// }
+ /// ```
+ ///
+ /// and we have a SyntaxContext that is referring to something declared by an invocation
+ /// of g (call it g1), calling remove_mark will result in the SyntaxContext for the
+ /// invocation of f that created g1.
+ /// Returns the mark that was removed.
+ pub fn remove_mark(&mut self) -> ExpnId {
+ HygieneData::with(|data| data.remove_mark(self).0)
+ }
+
+ pub fn marks(self) -> Vec<(ExpnId, Transparency)> {
+ HygieneData::with(|data| data.marks(self))
+ }
+
+ /// Adjust this context for resolution in a scope created by the given expansion.
+ /// For example, consider the following three resolutions of `f`:
+ ///
+ /// ```rust
+ /// #![feature(decl_macro)]
+ /// mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
+ /// m!(f);
+ /// macro m($f:ident) {
+ /// mod bar {
+ /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
+ /// pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
+ /// }
+ /// foo::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
+ /// //^ Since `mod foo` is outside this expansion, `adjust` removes the mark from `f`,
+ /// //| and it resolves to `::foo::f`.
+ /// bar::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
+ /// //^ Since `mod bar` not outside this expansion, `adjust` does not change `f`,
+ /// //| and it resolves to `::bar::f`.
+ /// bar::$f(); // `f`'s `SyntaxContext` is empty.
+ /// //^ Since `mod bar` is not outside this expansion, `adjust` does not change `$f`,
+ /// //| and it resolves to `::bar::$f`.
+ /// }
+ /// ```
+ /// This returns the expansion whose definition scope we use to privacy check the resolution,
+ /// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope).
+ pub fn adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
+ HygieneData::with(|data| data.adjust(self, expn_id))
+ }
+
+ /// Like `SyntaxContext::adjust`, but also normalizes `self` to macros 2.0.
+ pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
+ HygieneData::with(|data| {
+ *self = data.normalize_to_macros_2_0(*self);
+ data.adjust(self, expn_id)
+ })
+ }
+
+ /// Adjust this context for resolution in a scope created by the given expansion
+ /// via a glob import with the given `SyntaxContext`.
+ /// For example:
+ ///
+ /// ```compile_fail,E0425
+ /// #![feature(decl_macro)]
+ /// m!(f);
+ /// macro m($i:ident) {
+ /// mod foo {
+ /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
+ /// pub fn $i() {} // `$i`'s `SyntaxContext` is empty.
+ /// }
+ /// n!(f);
+ /// macro n($j:ident) {
+ /// use foo::*;
+ /// f(); // `f`'s `SyntaxContext` has a mark from `m` and a mark from `n`
+ /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::f`.
+ /// $i(); // `$i`'s `SyntaxContext` has a mark from `n`
+ /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::$i`.
+ /// $j(); // `$j`'s `SyntaxContext` has a mark from `m`
+ /// //^ This cannot be glob-adjusted, so this is a resolution error.
+ /// }
+ /// }
+ /// ```
+ /// This returns `None` if the context cannot be glob-adjusted.
+ /// Otherwise, it returns the scope to use when privacy checking (see `adjust` for details).
+ pub fn glob_adjust(&mut self, expn_id: ExpnId, glob_span: Span) -> Option<Option<ExpnId>> {
+ HygieneData::with(|data| {
+ let mut scope = None;
+ let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
+ while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
+ scope = Some(data.remove_mark(&mut glob_ctxt).0);
+ if data.remove_mark(self).0 != scope.unwrap() {
+ return None;
+ }
+ }
+ if data.adjust(self, expn_id).is_some() {
+ return None;
+ }
+ Some(scope)
+ })
+ }
+
+ /// Undo `glob_adjust` if possible:
+ ///
+ /// ```ignore (illustrative)
+ /// if let Some(privacy_checking_scope) = self.reverse_glob_adjust(expansion, glob_ctxt) {
+ /// assert!(self.glob_adjust(expansion, glob_ctxt) == Some(privacy_checking_scope));
+ /// }
+ /// ```
+ pub fn reverse_glob_adjust(
+ &mut self,
+ expn_id: ExpnId,
+ glob_span: Span,
+ ) -> Option<Option<ExpnId>> {
+ HygieneData::with(|data| {
+ if data.adjust(self, expn_id).is_some() {
+ return None;
+ }
+
+ let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
+ let mut marks = Vec::new();
+ while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
+ marks.push(data.remove_mark(&mut glob_ctxt));
+ }
+
+ let scope = marks.last().map(|mark| mark.0);
+ while let Some((expn_id, transparency)) = marks.pop() {
+ *self = data.apply_mark(*self, expn_id, transparency);
+ }
+ Some(scope)
+ })
+ }
+
+ pub fn hygienic_eq(self, other: SyntaxContext, expn_id: ExpnId) -> bool {
+ HygieneData::with(|data| {
+ let mut self_normalized = data.normalize_to_macros_2_0(self);
+ data.adjust(&mut self_normalized, expn_id);
+ self_normalized == data.normalize_to_macros_2_0(other)
+ })
+ }
+
+ #[inline]
+ pub fn normalize_to_macros_2_0(self) -> SyntaxContext {
+ HygieneData::with(|data| data.normalize_to_macros_2_0(self))
+ }
+
+ #[inline]
+ pub fn normalize_to_macro_rules(self) -> SyntaxContext {
+ HygieneData::with(|data| data.normalize_to_macro_rules(self))
+ }
+
+ #[inline]
+ pub fn outer_expn(self) -> ExpnId {
+ HygieneData::with(|data| data.outer_expn(self))
+ }
+
+ /// `ctxt.outer_expn_data()` is equivalent to but faster than
+ /// `ctxt.outer_expn().expn_data()`.
+ #[inline]
+ pub fn outer_expn_data(self) -> ExpnData {
+ HygieneData::with(|data| data.expn_data(data.outer_expn(self)).clone())
+ }
+
+ #[inline]
+ pub fn outer_mark(self) -> (ExpnId, Transparency) {
+ HygieneData::with(|data| data.outer_mark(self))
+ }
+
+ pub fn dollar_crate_name(self) -> Symbol {
+ HygieneData::with(|data| data.syntax_context_data[self.0 as usize].dollar_crate_name)
+ }
+
+ pub fn edition(self) -> Edition {
+ HygieneData::with(|data| data.expn_data(data.outer_expn(self)).edition)
+ }
+}
+
+impl fmt::Debug for SyntaxContext {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(f, "#{}", self.0)
+ }
+}
+
+impl Span {
+ /// Creates a fresh expansion with given properties.
+ /// Expansions are normally created by macros, but in some cases expansions are created for
+ /// other compiler-generated code to set per-span properties like allowed unstable features.
+ /// The returned span belongs to the created expansion and has the new properties,
+ /// but its location is inherited from the current span.
+ pub fn fresh_expansion(self, expn_id: LocalExpnId) -> Span {
+ HygieneData::with(|data| {
+ self.with_ctxt(data.apply_mark(
+ SyntaxContext::root(),
+ expn_id.to_expn_id(),
+ Transparency::Transparent,
+ ))
+ })
+ }
+
+ /// Reuses the span but adds information like the kind of the desugaring and features that are
+ /// allowed inside this span.
+ pub fn mark_with_reason(
+ self,
+ allow_internal_unstable: Option<Lrc<[Symbol]>>,
+ reason: DesugaringKind,
+ edition: Edition,
+ ctx: impl HashStableContext,
+ ) -> Span {
+ let expn_data = ExpnData {
+ allow_internal_unstable,
+ ..ExpnData::default(ExpnKind::Desugaring(reason), self, edition, None, None)
+ };
+ let expn_id = LocalExpnId::fresh(expn_data, ctx);
+ self.fresh_expansion(expn_id)
+ }
+}
+
+/// A subset of properties from both macro definition and macro call available through global data.
+/// Avoid using this if you have access to the original definition or call structures.
+#[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
+pub struct ExpnData {
+ // --- The part unique to each expansion.
+ /// The kind of this expansion - macro or compiler desugaring.
+ pub kind: ExpnKind,
+ /// The expansion that produced this expansion.
+ pub parent: ExpnId,
+ /// The location of the actual macro invocation or syntax sugar , e.g.
+ /// `let x = foo!();` or `if let Some(y) = x {}`
+ ///
+ /// This may recursively refer to other macro invocations, e.g., if
+ /// `foo!()` invoked `bar!()` internally, and there was an
+ /// expression inside `bar!`; the call_site of the expression in
+ /// the expansion would point to the `bar!` invocation; that
+ /// call_site span would have its own ExpnData, with the call_site
+ /// pointing to the `foo!` invocation.
+ pub call_site: Span,
+ /// Used to force two `ExpnData`s to have different `Fingerprint`s.
+ /// Due to macro expansion, it's possible to end up with two `ExpnId`s
+ /// that have identical `ExpnData`s. This violates the contract of `HashStable`
+ /// - the two `ExpnId`s are not equal, but their `Fingerprint`s are equal
+ /// (since the numerical `ExpnId` value is not considered by the `HashStable`
+ /// implementation).
+ ///
+ /// The `disambiguator` field is set by `update_disambiguator` when two distinct
+ /// `ExpnId`s would end up with the same `Fingerprint`. Since `ExpnData` includes
+ /// a `krate` field, this value only needs to be unique within a single crate.
+ disambiguator: u32,
+
+ // --- The part specific to the macro/desugaring definition.
+ // --- It may be reasonable to share this part between expansions with the same definition,
+ // --- but such sharing is known to bring some minor inconveniences without also bringing
+ // --- noticeable perf improvements (PR #62898).
+ /// The span of the macro definition (possibly dummy).
+ /// This span serves only informational purpose and is not used for resolution.
+ pub def_site: Span,
+ /// List of `#[unstable]`/feature-gated features that the macro is allowed to use
+ /// internally without forcing the whole crate to opt-in
+ /// to them.
+ pub allow_internal_unstable: Option<Lrc<[Symbol]>>,
+ /// Whether the macro is allowed to use `unsafe` internally
+ /// even if the user crate has `#![forbid(unsafe_code)]`.
+ pub allow_internal_unsafe: bool,
+ /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`)
+ /// for a given macro.
+ pub local_inner_macros: bool,
+ /// Edition of the crate in which the macro is defined.
+ pub edition: Edition,
+ /// The `DefId` of the macro being invoked,
+ /// if this `ExpnData` corresponds to a macro invocation
+ pub macro_def_id: Option<DefId>,
+ /// The normal module (`mod`) in which the expanded macro was defined.
+ pub parent_module: Option<DefId>,
+}
+
+impl !PartialEq for ExpnData {}
+impl !Hash for ExpnData {}
+
+impl ExpnData {
+ pub fn new(
+ kind: ExpnKind,
+ parent: ExpnId,
+ call_site: Span,
+ def_site: Span,
+ allow_internal_unstable: Option<Lrc<[Symbol]>>,
+ allow_internal_unsafe: bool,
+ local_inner_macros: bool,
+ edition: Edition,
+ macro_def_id: Option<DefId>,
+ parent_module: Option<DefId>,
+ ) -> ExpnData {
+ ExpnData {
+ kind,
+ parent,
+ call_site,
+ def_site,
+ allow_internal_unstable,
+ allow_internal_unsafe,
+ local_inner_macros,
+ edition,
+ macro_def_id,
+ parent_module,
+ disambiguator: 0,
+ }
+ }
+
+ /// Constructs expansion data with default properties.
+ pub fn default(
+ kind: ExpnKind,
+ call_site: Span,
+ edition: Edition,
+ macro_def_id: Option<DefId>,
+ parent_module: Option<DefId>,
+ ) -> ExpnData {
+ ExpnData {
+ kind,
+ parent: ExpnId::root(),
+ call_site,
+ def_site: DUMMY_SP,
+ allow_internal_unstable: None,
+ allow_internal_unsafe: false,
+ local_inner_macros: false,
+ edition,
+ macro_def_id,
+ parent_module,
+ disambiguator: 0,
+ }
+ }
+
+ pub fn allow_unstable(
+ kind: ExpnKind,
+ call_site: Span,
+ edition: Edition,
+ allow_internal_unstable: Lrc<[Symbol]>,
+ macro_def_id: Option<DefId>,
+ parent_module: Option<DefId>,
+ ) -> ExpnData {
+ ExpnData {
+ allow_internal_unstable: Some(allow_internal_unstable),
+ ..ExpnData::default(kind, call_site, edition, macro_def_id, parent_module)
+ }
+ }
+
+ #[inline]
+ pub fn is_root(&self) -> bool {
+ matches!(self.kind, ExpnKind::Root)
+ }
+
+ #[inline]
+ fn hash_expn(&self, ctx: &mut impl HashStableContext) -> u64 {
+ let mut hasher = StableHasher::new();
+ self.hash_stable(ctx, &mut hasher);
+ hasher.finish()
+ }
+}
+
+/// Expansion kind.
+#[derive(Clone, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
+pub enum ExpnKind {
+ /// No expansion, aka root expansion. Only `ExpnId::root()` has this kind.
+ Root,
+ /// Expansion produced by a macro.
+ Macro(MacroKind, Symbol),
+ /// Transform done by the compiler on the AST.
+ AstPass(AstPass),
+ /// Desugaring done by the compiler during HIR lowering.
+ Desugaring(DesugaringKind),
+ /// MIR inlining
+ Inlined,
+}
+
+impl ExpnKind {
+ pub fn descr(&self) -> String {
+ match *self {
+ ExpnKind::Root => kw::PathRoot.to_string(),
+ ExpnKind::Macro(macro_kind, name) => match macro_kind {
+ MacroKind::Bang => format!("{}!", name),
+ MacroKind::Attr => format!("#[{}]", name),
+ MacroKind::Derive => format!("#[derive({})]", name),
+ },
+ ExpnKind::AstPass(kind) => kind.descr().to_string(),
+ ExpnKind::Desugaring(kind) => format!("desugaring of {}", kind.descr()),
+ ExpnKind::Inlined => "inlined source".to_string(),
+ }
+ }
+}
+
+/// The kind of macro invocation or definition.
+#[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
+#[derive(HashStable_Generic)]
+pub enum MacroKind {
+ /// A bang macro `foo!()`.
+ Bang,
+ /// An attribute macro `#[foo]`.
+ Attr,
+ /// A derive macro `#[derive(Foo)]`
+ Derive,
+}
+
+impl MacroKind {
+ pub fn descr(self) -> &'static str {
+ match self {
+ MacroKind::Bang => "macro",
+ MacroKind::Attr => "attribute macro",
+ MacroKind::Derive => "derive macro",
+ }
+ }
+
+ pub fn descr_expected(self) -> &'static str {
+ match self {
+ MacroKind::Attr => "attribute",
+ _ => self.descr(),
+ }
+ }
+
+ pub fn article(self) -> &'static str {
+ match self {
+ MacroKind::Attr => "an",
+ _ => "a",
+ }
+ }
+}
+
+/// The kind of AST transform.
+#[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
+pub enum AstPass {
+ StdImports,
+ TestHarness,
+ ProcMacroHarness,
+}
+
+impl AstPass {
+ pub fn descr(self) -> &'static str {
+ match self {
+ AstPass::StdImports => "standard library imports",
+ AstPass::TestHarness => "test harness",
+ AstPass::ProcMacroHarness => "proc macro harness",
+ }
+ }
+}
+
+/// The kind of compiler desugaring.
+#[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
+pub enum DesugaringKind {
+ /// We desugar `if c { i } else { e }` to `match $ExprKind::Use(c) { true => i, _ => e }`.
+ /// However, we do not want to blame `c` for unreachability but rather say that `i`
+ /// is unreachable. This desugaring kind allows us to avoid blaming `c`.
+ /// This also applies to `while` loops.
+ CondTemporary,
+ QuestionMark,
+ TryBlock,
+ YeetExpr,
+ /// Desugaring of an `impl Trait` in return type position
+ /// to an `type Foo = impl Trait;` and replacing the
+ /// `impl Trait` with `Foo`.
+ OpaqueTy,
+ Async,
+ Await,
+ ForLoop,
+ WhileLoop,
+}
+
+impl DesugaringKind {
+ /// The description wording should combine well with "desugaring of {}".
+ pub fn descr(self) -> &'static str {
+ match self {
+ DesugaringKind::CondTemporary => "`if` or `while` condition",
+ DesugaringKind::Async => "`async` block or function",
+ DesugaringKind::Await => "`await` expression",
+ DesugaringKind::QuestionMark => "operator `?`",
+ DesugaringKind::TryBlock => "`try` block",
+ DesugaringKind::YeetExpr => "`do yeet` expression",
+ DesugaringKind::OpaqueTy => "`impl Trait`",
+ DesugaringKind::ForLoop => "`for` loop",
+ DesugaringKind::WhileLoop => "`while` loop",
+ }
+ }
+}
+
+#[derive(Default)]
+pub struct HygieneEncodeContext {
+ /// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
+ /// This is `None` after we finish encoding `SyntaxContexts`, to ensure
+ /// that we don't accidentally try to encode any more `SyntaxContexts`
+ serialized_ctxts: Lock<FxHashSet<SyntaxContext>>,
+ /// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
+ /// in the most recent 'round' of serializing. Serializing `SyntaxContextData`
+ /// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
+ /// until we reach a fixed point.
+ latest_ctxts: Lock<FxHashSet<SyntaxContext>>,
+
+ serialized_expns: Lock<FxHashSet<ExpnId>>,
+
+ latest_expns: Lock<FxHashSet<ExpnId>>,
+}
+
+impl HygieneEncodeContext {
+ /// Record the fact that we need to serialize the corresponding `ExpnData`.
+ pub fn schedule_expn_data_for_encoding(&self, expn: ExpnId) {
+ if !self.serialized_expns.lock().contains(&expn) {
+ self.latest_expns.lock().insert(expn);
+ }
+ }
+
+ pub fn encode<T>(
+ &self,
+ encoder: &mut T,
+ mut encode_ctxt: impl FnMut(&mut T, u32, &SyntaxContextData),
+ mut encode_expn: impl FnMut(&mut T, ExpnId, &ExpnData, ExpnHash),
+ ) {
+ // When we serialize a `SyntaxContextData`, we may end up serializing
+ // a `SyntaxContext` that we haven't seen before
+ while !self.latest_ctxts.lock().is_empty() || !self.latest_expns.lock().is_empty() {
+ debug!(
+ "encode_hygiene: Serializing a round of {:?} SyntaxContextDatas: {:?}",
+ self.latest_ctxts.lock().len(),
+ self.latest_ctxts
+ );
+
+ // Consume the current round of SyntaxContexts.
+ // Drop the lock() temporary early
+ let latest_ctxts = { std::mem::take(&mut *self.latest_ctxts.lock()) };
+
+ // It's fine to iterate over a HashMap, because the serialization
+ // of the table that we insert data into doesn't depend on insertion
+ // order
+ #[allow(rustc::potential_query_instability)]
+ for_all_ctxts_in(latest_ctxts.into_iter(), |index, ctxt, data| {
+ if self.serialized_ctxts.lock().insert(ctxt) {
+ encode_ctxt(encoder, index, data);
+ }
+ });
+
+ let latest_expns = { std::mem::take(&mut *self.latest_expns.lock()) };
+
+ // Same as above, this is fine as we are inserting into a order-independent hashset
+ #[allow(rustc::potential_query_instability)]
+ for_all_expns_in(latest_expns.into_iter(), |expn, data, hash| {
+ if self.serialized_expns.lock().insert(expn) {
+ encode_expn(encoder, expn, data, hash);
+ }
+ });
+ }
+ debug!("encode_hygiene: Done serializing SyntaxContextData");
+ }
+}
+
+#[derive(Default)]
+/// Additional information used to assist in decoding hygiene data
+pub struct HygieneDecodeContext {
+ // Maps serialized `SyntaxContext` ids to a `SyntaxContext` in the current
+ // global `HygieneData`. When we deserialize a `SyntaxContext`, we need to create
+ // a new id in the global `HygieneData`. This map tracks the ID we end up picking,
+ // so that multiple occurrences of the same serialized id are decoded to the same
+ // `SyntaxContext`
+ remapped_ctxts: Lock<Vec<Option<SyntaxContext>>>,
+}
+
+/// Register an expansion which has been decoded from the on-disk-cache for the local crate.
+pub fn register_local_expn_id(data: ExpnData, hash: ExpnHash) -> ExpnId {
+ HygieneData::with(|hygiene_data| {
+ let expn_id = hygiene_data.local_expn_data.next_index();
+ hygiene_data.local_expn_data.push(Some(data));
+ let _eid = hygiene_data.local_expn_hashes.push(hash);
+ debug_assert_eq!(expn_id, _eid);
+
+ let expn_id = expn_id.to_expn_id();
+
+ let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
+ debug_assert!(_old_id.is_none());
+ expn_id
+ })
+}
+
+/// Register an expansion which has been decoded from the metadata of a foreign crate.
+pub fn register_expn_id(
+ krate: CrateNum,
+ local_id: ExpnIndex,
+ data: ExpnData,
+ hash: ExpnHash,
+) -> ExpnId {
+ debug_assert!(data.parent == ExpnId::root() || krate == data.parent.krate);
+ let expn_id = ExpnId { krate, local_id };
+ HygieneData::with(|hygiene_data| {
+ let _old_data = hygiene_data.foreign_expn_data.insert(expn_id, data);
+ debug_assert!(_old_data.is_none());
+ let _old_hash = hygiene_data.foreign_expn_hashes.insert(expn_id, hash);
+ debug_assert!(_old_hash.is_none());
+ let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
+ debug_assert!(_old_id.is_none());
+ });
+ expn_id
+}
+
+/// Decode an expansion from the metadata of a foreign crate.
+pub fn decode_expn_id(
+ krate: CrateNum,
+ index: u32,
+ decode_data: impl FnOnce(ExpnId) -> (ExpnData, ExpnHash),
+) -> ExpnId {
+ if index == 0 {
+ debug!("decode_expn_id: deserialized root");
+ return ExpnId::root();
+ }
+
+ let index = ExpnIndex::from_u32(index);
+
+ // This function is used to decode metadata, so it cannot decode information about LOCAL_CRATE.
+ debug_assert_ne!(krate, LOCAL_CRATE);
+ let expn_id = ExpnId { krate, local_id: index };
+
+ // Fast path if the expansion has already been decoded.
+ if HygieneData::with(|hygiene_data| hygiene_data.foreign_expn_data.contains_key(&expn_id)) {
+ return expn_id;
+ }
+
+ // Don't decode the data inside `HygieneData::with`, since we need to recursively decode
+ // other ExpnIds
+ let (expn_data, hash) = decode_data(expn_id);
+
+ register_expn_id(krate, index, expn_data, hash)
+}
+
+// Decodes `SyntaxContext`, using the provided `HygieneDecodeContext`
+// to track which `SyntaxContext`s we have already decoded.
+// The provided closure will be invoked to deserialize a `SyntaxContextData`
+// if we haven't already seen the id of the `SyntaxContext` we are deserializing.
+pub fn decode_syntax_context<D: Decoder, F: FnOnce(&mut D, u32) -> SyntaxContextData>(
+ d: &mut D,
+ context: &HygieneDecodeContext,
+ decode_data: F,
+) -> SyntaxContext {
+ let raw_id: u32 = Decodable::decode(d);
+ if raw_id == 0 {
+ debug!("decode_syntax_context: deserialized root");
+ // The root is special
+ return SyntaxContext::root();
+ }
+
+ let outer_ctxts = &context.remapped_ctxts;
+
+ // Ensure that the lock() temporary is dropped early
+ {
+ if let Some(ctxt) = outer_ctxts.lock().get(raw_id as usize).copied().flatten() {
+ return ctxt;
+ }
+ }
+
+ // Allocate and store SyntaxContext id *before* calling the decoder function,
+ // as the SyntaxContextData may reference itself.
+ let new_ctxt = HygieneData::with(|hygiene_data| {
+ let new_ctxt = SyntaxContext(hygiene_data.syntax_context_data.len() as u32);
+ // Push a dummy SyntaxContextData to ensure that nobody else can get the
+ // same ID as us. This will be overwritten after call `decode_Data`
+ hygiene_data.syntax_context_data.push(SyntaxContextData {
+ outer_expn: ExpnId::root(),
+ outer_transparency: Transparency::Transparent,
+ parent: SyntaxContext::root(),
+ opaque: SyntaxContext::root(),
+ opaque_and_semitransparent: SyntaxContext::root(),
+ dollar_crate_name: kw::Empty,
+ });
+ let mut ctxts = outer_ctxts.lock();
+ let new_len = raw_id as usize + 1;
+ if ctxts.len() < new_len {
+ ctxts.resize(new_len, None);
+ }
+ ctxts[raw_id as usize] = Some(new_ctxt);
+ drop(ctxts);
+ new_ctxt
+ });
+
+ // Don't try to decode data while holding the lock, since we need to
+ // be able to recursively decode a SyntaxContext
+ let mut ctxt_data = decode_data(d, raw_id);
+ // Reset `dollar_crate_name` so that it will be updated by `update_dollar_crate_names`
+ // We don't care what the encoding crate set this to - we want to resolve it
+ // from the perspective of the current compilation session
+ ctxt_data.dollar_crate_name = kw::DollarCrate;
+
+ // Overwrite the dummy data with our decoded SyntaxContextData
+ HygieneData::with(|hygiene_data| {
+ let dummy = std::mem::replace(
+ &mut hygiene_data.syntax_context_data[new_ctxt.as_u32() as usize],
+ ctxt_data,
+ );
+ // Make sure nothing weird happening while `decode_data` was running
+ assert_eq!(dummy.dollar_crate_name, kw::Empty);
+ });
+
+ new_ctxt
+}
+
+fn for_all_ctxts_in<F: FnMut(u32, SyntaxContext, &SyntaxContextData)>(
+ ctxts: impl Iterator<Item = SyntaxContext>,
+ mut f: F,
+) {
+ let all_data: Vec<_> = HygieneData::with(|data| {
+ ctxts.map(|ctxt| (ctxt, data.syntax_context_data[ctxt.0 as usize].clone())).collect()
+ });
+ for (ctxt, data) in all_data.into_iter() {
+ f(ctxt.0, ctxt, &data);
+ }
+}
+
+fn for_all_expns_in(
+ expns: impl Iterator<Item = ExpnId>,
+ mut f: impl FnMut(ExpnId, &ExpnData, ExpnHash),
+) {
+ let all_data: Vec<_> = HygieneData::with(|data| {
+ expns.map(|expn| (expn, data.expn_data(expn).clone(), data.expn_hash(expn))).collect()
+ });
+ for (expn, data, hash) in all_data.into_iter() {
+ f(expn, &data, hash);
+ }
+}
+
+impl<E: Encoder> Encodable<E> for LocalExpnId {
+ fn encode(&self, e: &mut E) {
+ self.to_expn_id().encode(e);
+ }
+}
+
+impl<E: Encoder> Encodable<E> for ExpnId {
+ default fn encode(&self, _: &mut E) {
+ panic!("cannot encode `ExpnId` with `{}`", std::any::type_name::<E>());
+ }
+}
+
+impl<D: Decoder> Decodable<D> for LocalExpnId {
+ fn decode(d: &mut D) -> Self {
+ ExpnId::expect_local(ExpnId::decode(d))
+ }
+}
+
+impl<D: Decoder> Decodable<D> for ExpnId {
+ default fn decode(_: &mut D) -> Self {
+ panic!("cannot decode `ExpnId` with `{}`", std::any::type_name::<D>());
+ }
+}
+
+pub fn raw_encode_syntax_context<E: Encoder>(
+ ctxt: SyntaxContext,
+ context: &HygieneEncodeContext,
+ e: &mut E,
+) {
+ if !context.serialized_ctxts.lock().contains(&ctxt) {
+ context.latest_ctxts.lock().insert(ctxt);
+ }
+ ctxt.0.encode(e);
+}
+
+impl<E: Encoder> Encodable<E> for SyntaxContext {
+ default fn encode(&self, _: &mut E) {
+ panic!("cannot encode `SyntaxContext` with `{}`", std::any::type_name::<E>());
+ }
+}
+
+impl<D: Decoder> Decodable<D> for SyntaxContext {
+ default fn decode(_: &mut D) -> Self {
+ panic!("cannot decode `SyntaxContext` with `{}`", std::any::type_name::<D>());
+ }
+}
+
+/// Updates the `disambiguator` field of the corresponding `ExpnData`
+/// such that the `Fingerprint` of the `ExpnData` does not collide with
+/// any other `ExpnIds`.
+///
+/// This method is called only when an `ExpnData` is first associated
+/// with an `ExpnId` (when the `ExpnId` is initially constructed, or via
+/// `set_expn_data`). It is *not* called for foreign `ExpnId`s deserialized
+/// from another crate's metadata - since `ExpnHash` includes the stable crate id,
+/// collisions are only possible between `ExpnId`s within the same crate.
+fn update_disambiguator(expn_data: &mut ExpnData, mut ctx: impl HashStableContext) -> ExpnHash {
+ // This disambiguator should not have been set yet.
+ assert_eq!(
+ expn_data.disambiguator, 0,
+ "Already set disambiguator for ExpnData: {:?}",
+ expn_data
+ );
+ assert_default_hashing_controls(&ctx, "ExpnData (disambiguator)");
+ let mut expn_hash = expn_data.hash_expn(&mut ctx);
+
+ let disambiguator = HygieneData::with(|data| {
+ // If this is the first ExpnData with a given hash, then keep our
+ // disambiguator at 0 (the default u32 value)
+ let disambig = data.expn_data_disambiguators.entry(expn_hash).or_default();
+ let disambiguator = *disambig;
+ *disambig += 1;
+ disambiguator
+ });
+
+ if disambiguator != 0 {
+ debug!("Set disambiguator for expn_data={:?} expn_hash={:?}", expn_data, expn_hash);
+
+ expn_data.disambiguator = disambiguator;
+ expn_hash = expn_data.hash_expn(&mut ctx);
+
+ // Verify that the new disambiguator makes the hash unique
+ #[cfg(debug_assertions)]
+ HygieneData::with(|data| {
+ assert_eq!(
+ data.expn_data_disambiguators.get(&expn_hash),
+ None,
+ "Hash collision after disambiguator update!",
+ );
+ });
+ }
+
+ ExpnHash::new(ctx.def_path_hash(LOCAL_CRATE.as_def_id()).stable_crate_id(), expn_hash)
+}
+
+impl<CTX: HashStableContext> HashStable<CTX> for SyntaxContext {
+ fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+ const TAG_EXPANSION: u8 = 0;
+ const TAG_NO_EXPANSION: u8 = 1;
+
+ if *self == SyntaxContext::root() {
+ TAG_NO_EXPANSION.hash_stable(ctx, hasher);
+ } else {
+ TAG_EXPANSION.hash_stable(ctx, hasher);
+ let (expn_id, transparency) = self.outer_mark();
+ expn_id.hash_stable(ctx, hasher);
+ transparency.hash_stable(ctx, hasher);
+ }
+ }
+}
+
+impl<CTX: HashStableContext> HashStable<CTX> for ExpnId {
+ fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+ assert_default_hashing_controls(ctx, "ExpnId");
+ let hash = if *self == ExpnId::root() {
+ // Avoid fetching TLS storage for a trivial often-used value.
+ Fingerprint::ZERO
+ } else {
+ self.expn_hash().0
+ };
+
+ hash.hash_stable(ctx, hasher);
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-12 10:31:36 +0000