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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /compiler/rustc_span/src/hygiene.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'compiler/rustc_span/src/hygiene.rs')
-rw-r--r-- | compiler/rustc_span/src/hygiene.rs | 1528 |
1 files changed, 1528 insertions, 0 deletions
diff --git a/compiler/rustc_span/src/hygiene.rs b/compiler/rustc_span/src/hygiene.rs new file mode 100644 index 000000000..e169d3c7c --- /dev/null +++ b/compiler/rustc_span/src/hygiene.rs @@ -0,0 +1,1528 @@ +//! 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); + } +} |