838 lines
31 KiB
Rust
838 lines
31 KiB
Rust
//! Machinery for hygienic macros, inspired by the `MTWT[1]` paper.
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//!
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//! `[1]` Matthew Flatt, Ryan Culpepper, David Darais, and Robert Bruce Findler. 2012.
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//! *Macros that work together: Compile-time bindings, partial expansion,
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//! and definition contexts*. J. Funct. Program. 22, 2 (March 2012), 181-216.
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//! DOI=10.1017/S0956796812000093 <https://doi.org/10.1017/S0956796812000093>
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// Hygiene data is stored in a global variable and accessed via TLS, which
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// means that accesses are somewhat expensive. (`HygieneData::with`
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// encapsulates a single access.) Therefore, on hot code paths it is worth
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// ensuring that multiple HygieneData accesses are combined into a single
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// `HygieneData::with`.
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//
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// This explains why `HygieneData`, `SyntaxContext` and `ExpnId` have interfaces
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// with a certain amount of redundancy in them. For example,
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// `SyntaxContext::outer_expn_data` combines `SyntaxContext::outer` and
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// `ExpnId::expn_data` so that two `HygieneData` accesses can be performed within
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// a single `HygieneData::with` call.
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//
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// It also explains why many functions appear in `HygieneData` and again in
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// `SyntaxContext` or `ExpnId`. For example, `HygieneData::outer` and
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// `SyntaxContext::outer` do the same thing, but the former is for use within a
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// `HygieneData::with` call while the latter is for use outside such a call.
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// When modifying this file it is important to understand this distinction,
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// because getting it wrong can lead to nested `HygieneData::with` calls that
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// trigger runtime aborts. (Fortunately these are obvious and easy to fix.)
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use crate::edition::Edition;
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use crate::symbol::{kw, sym, Symbol};
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use crate::GLOBALS;
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use crate::{Span, DUMMY_SP};
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use rustc_data_structures::fx::FxHashMap;
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use rustc_data_structures::sync::Lrc;
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use rustc_macros::HashStable_Generic;
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use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
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use std::fmt;
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/// A `SyntaxContext` represents a chain of pairs `(ExpnId, Transparency)` named "marks".
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#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
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pub struct SyntaxContext(u32);
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#[derive(Debug)]
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struct SyntaxContextData {
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outer_expn: ExpnId,
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outer_transparency: Transparency,
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parent: SyntaxContext,
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/// This context, but with all transparent and semi-transparent expansions filtered away.
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opaque: SyntaxContext,
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/// This context, but with all transparent expansions filtered away.
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opaque_and_semitransparent: SyntaxContext,
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/// Name of the crate to which `$crate` with this context would resolve.
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dollar_crate_name: Symbol,
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}
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/// A unique ID associated with a macro invocation and expansion.
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#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
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pub struct ExpnId(u32);
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/// A property of a macro expansion that determines how identifiers
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/// produced by that expansion are resolved.
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Hash, Debug, RustcEncodable, RustcDecodable)]
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#[derive(HashStable_Generic)]
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pub enum Transparency {
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/// Identifier produced by a transparent expansion is always resolved at call-site.
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/// Call-site spans in procedural macros, hygiene opt-out in `macro` should use this.
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Transparent,
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/// Identifier produced by a semi-transparent expansion may be resolved
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/// either at call-site or at definition-site.
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/// If it's a local variable, label or `$crate` then it's resolved at def-site.
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/// Otherwise it's resolved at call-site.
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/// `macro_rules` macros behave like this, built-in macros currently behave like this too,
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/// but that's an implementation detail.
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SemiTransparent,
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/// Identifier produced by an opaque expansion is always resolved at definition-site.
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/// Def-site spans in procedural macros, identifiers from `macro` by default use this.
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Opaque,
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}
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impl ExpnId {
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pub fn fresh(expn_data: Option<ExpnData>) -> Self {
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HygieneData::with(|data| data.fresh_expn(expn_data))
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}
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/// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
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#[inline]
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pub fn root() -> Self {
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ExpnId(0)
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}
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#[inline]
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pub fn as_u32(self) -> u32 {
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self.0
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}
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#[inline]
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pub fn from_u32(raw: u32) -> ExpnId {
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ExpnId(raw)
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}
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#[inline]
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pub fn expn_data(self) -> ExpnData {
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HygieneData::with(|data| data.expn_data(self).clone())
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}
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#[inline]
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pub fn set_expn_data(self, expn_data: ExpnData) {
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HygieneData::with(|data| {
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let old_expn_data = &mut data.expn_data[self.0 as usize];
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assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
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*old_expn_data = Some(expn_data);
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})
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}
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pub fn is_descendant_of(self, ancestor: ExpnId) -> bool {
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HygieneData::with(|data| data.is_descendant_of(self, ancestor))
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}
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/// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
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/// `expn_id.is_descendant_of(ctxt.outer_expn())`.
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pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
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HygieneData::with(|data| data.is_descendant_of(self, data.outer_expn(ctxt)))
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}
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/// Returns span for the macro which originally caused this expansion to happen.
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///
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/// Stops backtracing at include! boundary.
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pub fn expansion_cause(mut self) -> Option<Span> {
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let mut last_macro = None;
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loop {
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let expn_data = self.expn_data();
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// Stop going up the backtrace once include! is encountered
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if expn_data.is_root()
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|| expn_data.kind == ExpnKind::Macro(MacroKind::Bang, sym::include)
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{
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break;
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}
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self = expn_data.call_site.ctxt().outer_expn();
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last_macro = Some(expn_data.call_site);
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}
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last_macro
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}
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}
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#[derive(Debug)]
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crate struct HygieneData {
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/// Each expansion should have an associated expansion data, but sometimes there's a delay
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/// between creation of an expansion ID and obtaining its data (e.g. macros are collected
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/// first and then resolved later), so we use an `Option` here.
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expn_data: Vec<Option<ExpnData>>,
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syntax_context_data: Vec<SyntaxContextData>,
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syntax_context_map: FxHashMap<(SyntaxContext, ExpnId, Transparency), SyntaxContext>,
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}
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impl HygieneData {
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crate fn new(edition: Edition) -> Self {
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HygieneData {
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expn_data: vec![Some(ExpnData::default(ExpnKind::Root, DUMMY_SP, edition))],
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syntax_context_data: vec![SyntaxContextData {
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outer_expn: ExpnId::root(),
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outer_transparency: Transparency::Opaque,
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parent: SyntaxContext(0),
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opaque: SyntaxContext(0),
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opaque_and_semitransparent: SyntaxContext(0),
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dollar_crate_name: kw::DollarCrate,
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}],
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syntax_context_map: FxHashMap::default(),
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}
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}
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fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
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GLOBALS.with(|globals| f(&mut *globals.hygiene_data.borrow_mut()))
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}
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fn fresh_expn(&mut self, expn_data: Option<ExpnData>) -> ExpnId {
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self.expn_data.push(expn_data);
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ExpnId(self.expn_data.len() as u32 - 1)
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}
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fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
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self.expn_data[expn_id.0 as usize].as_ref().expect("no expansion data for an expansion ID")
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}
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fn is_descendant_of(&self, mut expn_id: ExpnId, ancestor: ExpnId) -> bool {
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while expn_id != ancestor {
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if expn_id == ExpnId::root() {
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return false;
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}
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expn_id = self.expn_data(expn_id).parent;
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}
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true
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}
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fn normalize_to_macros_2_0(&self, ctxt: SyntaxContext) -> SyntaxContext {
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self.syntax_context_data[ctxt.0 as usize].opaque
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}
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fn normalize_to_macro_rules(&self, ctxt: SyntaxContext) -> SyntaxContext {
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self.syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent
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}
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fn outer_expn(&self, ctxt: SyntaxContext) -> ExpnId {
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self.syntax_context_data[ctxt.0 as usize].outer_expn
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}
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fn outer_mark(&self, ctxt: SyntaxContext) -> (ExpnId, Transparency) {
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let data = &self.syntax_context_data[ctxt.0 as usize];
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(data.outer_expn, data.outer_transparency)
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}
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fn parent_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext {
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self.syntax_context_data[ctxt.0 as usize].parent
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}
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fn remove_mark(&self, ctxt: &mut SyntaxContext) -> (ExpnId, Transparency) {
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let outer_mark = self.outer_mark(*ctxt);
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*ctxt = self.parent_ctxt(*ctxt);
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outer_mark
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}
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fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
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let mut marks = Vec::new();
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while ctxt != SyntaxContext::root() {
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marks.push(self.outer_mark(ctxt));
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ctxt = self.parent_ctxt(ctxt);
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}
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marks.reverse();
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marks
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}
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fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span {
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while span.from_expansion() && span.ctxt() != to {
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span = self.expn_data(self.outer_expn(span.ctxt())).call_site;
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}
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span
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}
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fn adjust(&self, ctxt: &mut SyntaxContext, expn_id: ExpnId) -> Option<ExpnId> {
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let mut scope = None;
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while !self.is_descendant_of(expn_id, self.outer_expn(*ctxt)) {
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scope = Some(self.remove_mark(ctxt).0);
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}
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scope
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}
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fn apply_mark(
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&mut self,
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ctxt: SyntaxContext,
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expn_id: ExpnId,
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transparency: Transparency,
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) -> SyntaxContext {
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assert_ne!(expn_id, ExpnId::root());
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if transparency == Transparency::Opaque {
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return self.apply_mark_internal(ctxt, expn_id, transparency);
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}
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let call_site_ctxt = self.expn_data(expn_id).call_site.ctxt();
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let mut call_site_ctxt = if transparency == Transparency::SemiTransparent {
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self.normalize_to_macros_2_0(call_site_ctxt)
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} else {
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self.normalize_to_macro_rules(call_site_ctxt)
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};
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if call_site_ctxt == SyntaxContext::root() {
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return self.apply_mark_internal(ctxt, expn_id, transparency);
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}
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// Otherwise, `expn_id` is a macros 1.0 definition and the call site is in a
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// macros 2.0 expansion, i.e., a macros 1.0 invocation is in a macros 2.0 definition.
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//
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// In this case, the tokens from the macros 1.0 definition inherit the hygiene
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// at their invocation. That is, we pretend that the macros 1.0 definition
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// was defined at its invocation (i.e., inside the macros 2.0 definition)
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// so that the macros 2.0 definition remains hygienic.
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//
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// See the example at `test/ui/hygiene/legacy_interaction.rs`.
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for (expn_id, transparency) in self.marks(ctxt) {
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call_site_ctxt = self.apply_mark_internal(call_site_ctxt, expn_id, transparency);
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}
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self.apply_mark_internal(call_site_ctxt, expn_id, transparency)
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}
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fn apply_mark_internal(
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&mut self,
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ctxt: SyntaxContext,
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expn_id: ExpnId,
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transparency: Transparency,
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) -> SyntaxContext {
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let syntax_context_data = &mut self.syntax_context_data;
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let mut opaque = syntax_context_data[ctxt.0 as usize].opaque;
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let mut opaque_and_semitransparent =
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syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent;
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if transparency >= Transparency::Opaque {
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let parent = opaque;
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opaque = *self
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.syntax_context_map
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.entry((parent, expn_id, transparency))
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.or_insert_with(|| {
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let new_opaque = SyntaxContext(syntax_context_data.len() as u32);
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syntax_context_data.push(SyntaxContextData {
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outer_expn: expn_id,
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outer_transparency: transparency,
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parent,
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opaque: new_opaque,
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opaque_and_semitransparent: new_opaque,
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dollar_crate_name: kw::DollarCrate,
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});
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new_opaque
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});
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}
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if transparency >= Transparency::SemiTransparent {
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let parent = opaque_and_semitransparent;
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opaque_and_semitransparent = *self
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.syntax_context_map
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.entry((parent, expn_id, transparency))
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.or_insert_with(|| {
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let new_opaque_and_semitransparent =
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SyntaxContext(syntax_context_data.len() as u32);
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syntax_context_data.push(SyntaxContextData {
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outer_expn: expn_id,
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outer_transparency: transparency,
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parent,
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opaque,
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opaque_and_semitransparent: new_opaque_and_semitransparent,
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dollar_crate_name: kw::DollarCrate,
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});
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new_opaque_and_semitransparent
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});
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}
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let parent = ctxt;
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*self.syntax_context_map.entry((parent, expn_id, transparency)).or_insert_with(|| {
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let new_opaque_and_semitransparent_and_transparent =
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SyntaxContext(syntax_context_data.len() as u32);
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syntax_context_data.push(SyntaxContextData {
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outer_expn: expn_id,
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outer_transparency: transparency,
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parent,
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opaque,
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opaque_and_semitransparent,
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dollar_crate_name: kw::DollarCrate,
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});
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new_opaque_and_semitransparent_and_transparent
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})
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}
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}
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pub fn clear_syntax_context_map() {
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HygieneData::with(|data| data.syntax_context_map = FxHashMap::default());
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}
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pub fn walk_chain(span: Span, to: SyntaxContext) -> Span {
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HygieneData::with(|data| data.walk_chain(span, to))
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}
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pub fn update_dollar_crate_names(mut get_name: impl FnMut(SyntaxContext) -> Symbol) {
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// The new contexts that need updating are at the end of the list and have `$crate` as a name.
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let (len, to_update) = HygieneData::with(|data| {
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(
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data.syntax_context_data.len(),
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data.syntax_context_data
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.iter()
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.rev()
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.take_while(|scdata| scdata.dollar_crate_name == kw::DollarCrate)
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.count(),
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)
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});
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// The callback must be called from outside of the `HygieneData` lock,
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// since it will try to acquire it too.
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let range_to_update = len - to_update..len;
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let names: Vec<_> =
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range_to_update.clone().map(|idx| get_name(SyntaxContext::from_u32(idx as u32))).collect();
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HygieneData::with(|data| {
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range_to_update.zip(names.into_iter()).for_each(|(idx, name)| {
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data.syntax_context_data[idx].dollar_crate_name = name;
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})
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})
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}
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pub fn debug_hygiene_data(verbose: bool) -> String {
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HygieneData::with(|data| {
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if verbose {
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format!("{:#?}", data)
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} else {
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let mut s = String::from("");
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s.push_str("Expansions:");
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data.expn_data.iter().enumerate().for_each(|(id, expn_info)| {
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let expn_info = expn_info.as_ref().expect("no expansion data for an expansion ID");
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s.push_str(&format!(
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"\n{}: parent: {:?}, call_site_ctxt: {:?}, kind: {:?}",
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id,
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expn_info.parent,
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expn_info.call_site.ctxt(),
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expn_info.kind,
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));
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});
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s.push_str("\n\nSyntaxContexts:");
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data.syntax_context_data.iter().enumerate().for_each(|(id, ctxt)| {
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s.push_str(&format!(
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"\n#{}: parent: {:?}, outer_mark: ({:?}, {:?})",
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id, ctxt.parent, ctxt.outer_expn, ctxt.outer_transparency,
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));
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});
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s
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}
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})
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}
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impl SyntaxContext {
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#[inline]
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pub const fn root() -> Self {
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SyntaxContext(0)
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}
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#[inline]
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crate fn as_u32(self) -> u32 {
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self.0
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}
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#[inline]
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crate fn from_u32(raw: u32) -> SyntaxContext {
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SyntaxContext(raw)
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}
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/// Extend a syntax context with a given expansion and transparency.
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crate fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext {
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HygieneData::with(|data| data.apply_mark(self, expn_id, transparency))
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}
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/// Pulls a single mark off of the syntax context. This effectively moves the
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/// context up one macro definition level. That is, if we have a nested macro
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/// definition as follows:
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///
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/// ```rust
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/// macro_rules! f {
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/// macro_rules! g {
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/// ...
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/// }
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/// }
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/// ```
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///
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/// and we have a SyntaxContext that is referring to something declared by an invocation
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/// of g (call it g1), calling remove_mark will result in the SyntaxContext for the
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/// invocation of f that created g1.
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/// Returns the mark that was removed.
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pub fn remove_mark(&mut self) -> ExpnId {
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HygieneData::with(|data| data.remove_mark(self).0)
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}
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pub fn marks(self) -> Vec<(ExpnId, Transparency)> {
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HygieneData::with(|data| data.marks(self))
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}
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/// Adjust this context for resolution in a scope created by the given expansion.
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/// For example, consider the following three resolutions of `f`:
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///
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/// ```rust
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/// mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
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/// m!(f);
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/// 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::$f`.
|
|
/// }
|
|
/// ```
|
|
/// This returns the expansion whose definition scope we use to privacy check the resolution,
|
|
/// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope).
|
|
pub fn adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
|
|
HygieneData::with(|data| data.adjust(self, expn_id))
|
|
}
|
|
|
|
/// Like `SyntaxContext::adjust`, but also normalizes `self` to macros 2.0.
|
|
pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
|
|
HygieneData::with(|data| {
|
|
*self = data.normalize_to_macros_2_0(*self);
|
|
data.adjust(self, expn_id)
|
|
})
|
|
}
|
|
|
|
/// Adjust this context for resolution in a scope created by the given expansion
|
|
/// via a glob import with the given `SyntaxContext`.
|
|
/// For example:
|
|
///
|
|
/// ```rust
|
|
/// m!(f);
|
|
/// macro m($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:
|
|
///
|
|
/// ```rust
|
|
/// 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_with_data(self) -> (ExpnId, Transparency, ExpnData) {
|
|
HygieneData::with(|data| {
|
|
let (expn_id, transparency) = data.outer_mark(self);
|
|
(expn_id, transparency, data.expn_data(expn_id).clone())
|
|
})
|
|
}
|
|
|
|
pub fn dollar_crate_name(self) -> Symbol {
|
|
HygieneData::with(|data| data.syntax_context_data[self.0 as usize].dollar_crate_name)
|
|
}
|
|
}
|
|
|
|
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_data: ExpnData) -> Span {
|
|
self.fresh_expansion_with_transparency(expn_data, Transparency::Transparent)
|
|
}
|
|
|
|
pub fn fresh_expansion_with_transparency(
|
|
self,
|
|
expn_data: ExpnData,
|
|
transparency: Transparency,
|
|
) -> Span {
|
|
HygieneData::with(|data| {
|
|
let expn_id = data.fresh_expn(Some(expn_data));
|
|
self.with_ctxt(data.apply_mark(SyntaxContext::root(), expn_id, transparency))
|
|
})
|
|
}
|
|
}
|
|
|
|
/// 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, RustcEncodable, RustcDecodable, 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.
|
|
#[stable_hasher(ignore)]
|
|
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,
|
|
|
|
// --- 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,
|
|
}
|
|
|
|
impl ExpnData {
|
|
/// Constructs expansion data with default properties.
|
|
pub fn default(kind: ExpnKind, call_site: Span, edition: Edition) -> 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,
|
|
}
|
|
}
|
|
|
|
pub fn allow_unstable(
|
|
kind: ExpnKind,
|
|
call_site: Span,
|
|
edition: Edition,
|
|
allow_internal_unstable: Lrc<[Symbol]>,
|
|
) -> ExpnData {
|
|
ExpnData {
|
|
allow_internal_unstable: Some(allow_internal_unstable),
|
|
..ExpnData::default(kind, call_site, edition)
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
pub fn is_root(&self) -> bool {
|
|
if let ExpnKind::Root = self.kind { true } else { false }
|
|
}
|
|
}
|
|
|
|
/// Expansion kind.
|
|
#[derive(Clone, Debug, PartialEq, RustcEncodable, RustcDecodable, 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),
|
|
}
|
|
|
|
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()),
|
|
}
|
|
}
|
|
}
|
|
|
|
/// The kind of macro invocation or definition.
|
|
#[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, 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, PartialEq, Debug, RustcEncodable, RustcDecodable, HashStable_Generic)]
|
|
pub enum AstPass {
|
|
StdImports,
|
|
TestHarness,
|
|
ProcMacroHarness,
|
|
}
|
|
|
|
impl AstPass {
|
|
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, RustcEncodable, RustcDecodable, 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,
|
|
/// 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,
|
|
}
|
|
|
|
impl DesugaringKind {
|
|
/// The description wording should combine well with "desugaring of {}".
|
|
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::OpaqueTy => "`impl Trait`",
|
|
DesugaringKind::ForLoop => "`for` loop",
|
|
}
|
|
}
|
|
}
|
|
|
|
impl Encodable for ExpnId {
|
|
fn encode<E: Encoder>(&self, _: &mut E) -> Result<(), E::Error> {
|
|
Ok(()) // FIXME(jseyfried) intercrate hygiene
|
|
}
|
|
}
|
|
|
|
impl Decodable for ExpnId {
|
|
fn decode<D: Decoder>(_: &mut D) -> Result<Self, D::Error> {
|
|
Ok(ExpnId::root()) // FIXME(jseyfried) intercrate hygiene
|
|
}
|
|
}
|