| //! Machinery for hygienic macros, inspired by the `MTWT[1]` paper. |
| //! |
| //! `[1]` Matthew Flatt, Ryan Culpepper, David Darais, and Robert Bruce Findler. 2012. |
| //! *Macros that work together: Compile-time bindings, partial expansion, |
| //! and definition contexts*. J. Funct. Program. 22, 2 (March 2012), 181-216. |
| //! DOI=10.1017/S0956796812000093 <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 `Mark` have interfaces |
| // with a certain amount of redundancy in them. For example, |
| // `SyntaxContext::outer_expn_info` combines `SyntaxContext::outer` and |
| // `Mark::expn_info` 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 `Mark`. 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::GLOBALS; |
| use crate::Span; |
| use crate::edition::Edition; |
| use crate::symbol::{kw, Symbol}; |
| |
| use serialize::{Encodable, Decodable, Encoder, Decoder}; |
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
| use rustc_data_structures::sync::Lrc; |
| use std::{fmt, mem}; |
| |
| /// A SyntaxContext represents a chain of macro expansions (represented by marks). |
| #[derive(Clone, Copy, PartialEq, Eq, Default, PartialOrd, Ord, Hash)] |
| pub struct SyntaxContext(u32); |
| |
| #[derive(Copy, Clone, Debug)] |
| struct SyntaxContextData { |
| outer_mark: Mark, |
| transparency: Transparency, |
| prev_ctxt: SyntaxContext, |
| /// This context, but with all transparent and semi-transparent marks filtered away. |
| opaque: SyntaxContext, |
| /// This context, but with all transparent marks filtered away. |
| opaque_and_semitransparent: SyntaxContext, |
| /// Name of the crate to which `$crate` with this context would resolve. |
| dollar_crate_name: Symbol, |
| } |
| |
| /// A mark is a unique ID associated with a macro expansion. |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] |
| pub struct Mark(u32); |
| |
| #[derive(Clone, Debug)] |
| struct MarkData { |
| parent: Mark, |
| default_transparency: Transparency, |
| expn_info: Option<ExpnInfo>, |
| } |
| |
| /// A property of a macro expansion that determines how identifiers |
| /// produced by that expansion are resolved. |
| #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Hash, Debug)] |
| pub enum Transparency { |
| /// Identifier produced by a transparent expansion is always resolved at call-site. |
| /// Call-site spans in procedural macros, hygiene opt-out in `macro` should use this. |
| Transparent, |
| /// Identifier produced by a semi-transparent expansion may be resolved |
| /// either at call-site or at definition-site. |
| /// If it's a local variable, label or `$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 Mark { |
| pub fn fresh(parent: Mark) -> Self { |
| HygieneData::with(|data| { |
| data.marks.push(MarkData { |
| parent, |
| // By default expansions behave like `macro_rules`. |
| default_transparency: Transparency::SemiTransparent, |
| expn_info: None, |
| }); |
| Mark(data.marks.len() as u32 - 1) |
| }) |
| } |
| |
| /// The mark of the theoretical expansion that generates freshly parsed, unexpanded AST. |
| #[inline] |
| pub fn root() -> Self { |
| Mark(0) |
| } |
| |
| #[inline] |
| pub fn as_u32(self) -> u32 { |
| self.0 |
| } |
| |
| #[inline] |
| pub fn from_u32(raw: u32) -> Mark { |
| Mark(raw) |
| } |
| |
| #[inline] |
| pub fn parent(self) -> Mark { |
| HygieneData::with(|data| data.marks[self.0 as usize].parent) |
| } |
| |
| #[inline] |
| pub fn expn_info(self) -> Option<ExpnInfo> { |
| HygieneData::with(|data| data.expn_info(self)) |
| } |
| |
| #[inline] |
| pub fn set_expn_info(self, info: ExpnInfo) { |
| HygieneData::with(|data| data.marks[self.0 as usize].expn_info = Some(info)) |
| } |
| |
| #[inline] |
| pub fn set_default_transparency(self, transparency: Transparency) { |
| assert_ne!(self, Mark::root()); |
| HygieneData::with(|data| data.marks[self.0 as usize].default_transparency = transparency) |
| } |
| |
| pub fn is_descendant_of(self, ancestor: Mark) -> bool { |
| HygieneData::with(|data| data.is_descendant_of(self, ancestor)) |
| } |
| |
| /// `mark.outer_is_descendant_of(ctxt)` is equivalent to but faster than |
| /// `mark.is_descendant_of(ctxt.outer())`. |
| pub fn outer_is_descendant_of(self, ctxt: SyntaxContext) -> bool { |
| HygieneData::with(|data| data.is_descendant_of(self, data.outer(ctxt))) |
| } |
| |
| /// Computes a mark such that both input marks are descendants of (or equal to) the returned |
| /// mark. That is, the following holds: |
| /// |
| /// ```rust |
| /// let la = least_ancestor(a, b); |
| /// assert!(a.is_descendant_of(la)) |
| /// assert!(b.is_descendant_of(la)) |
| /// ``` |
| pub fn least_ancestor(mut a: Mark, mut b: Mark) -> Mark { |
| HygieneData::with(|data| { |
| // Compute the path from a to the root |
| let mut a_path = FxHashSet::<Mark>::default(); |
| while a != Mark::root() { |
| a_path.insert(a); |
| a = data.marks[a.0 as usize].parent; |
| } |
| |
| // While the path from b to the root hasn't intersected, move up the tree |
| while !a_path.contains(&b) { |
| b = data.marks[b.0 as usize].parent; |
| } |
| |
| b |
| }) |
| } |
| |
| // Used for enabling some compatibility fallback in resolve. |
| #[inline] |
| pub fn looks_like_proc_macro_derive(self) -> bool { |
| HygieneData::with(|data| { |
| let mark_data = &data.marks[self.0 as usize]; |
| if mark_data.default_transparency == Transparency::Opaque { |
| if let Some(expn_info) = &mark_data.expn_info { |
| if let ExpnFormat::MacroAttribute(name) = expn_info.format { |
| if name.as_str().starts_with("derive(") { |
| return true; |
| } |
| } |
| } |
| } |
| false |
| }) |
| } |
| } |
| |
| #[derive(Debug)] |
| crate struct HygieneData { |
| marks: Vec<MarkData>, |
| syntax_contexts: Vec<SyntaxContextData>, |
| markings: FxHashMap<(SyntaxContext, Mark, Transparency), SyntaxContext>, |
| } |
| |
| impl HygieneData { |
| crate fn new() -> Self { |
| HygieneData { |
| marks: vec![MarkData { |
| parent: Mark::root(), |
| // If the root is opaque, then loops searching for an opaque mark |
| // will automatically stop after reaching it. |
| default_transparency: Transparency::Opaque, |
| expn_info: None, |
| }], |
| syntax_contexts: vec![SyntaxContextData { |
| outer_mark: Mark::root(), |
| transparency: Transparency::Opaque, |
| prev_ctxt: SyntaxContext(0), |
| opaque: SyntaxContext(0), |
| opaque_and_semitransparent: SyntaxContext(0), |
| dollar_crate_name: kw::DollarCrate, |
| }], |
| markings: FxHashMap::default(), |
| } |
| } |
| |
| fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T { |
| GLOBALS.with(|globals| f(&mut *globals.hygiene_data.borrow_mut())) |
| } |
| |
| fn expn_info(&self, mark: Mark) -> Option<ExpnInfo> { |
| self.marks[mark.0 as usize].expn_info.clone() |
| } |
| |
| fn is_descendant_of(&self, mut mark: Mark, ancestor: Mark) -> bool { |
| while mark != ancestor { |
| if mark == Mark::root() { |
| return false; |
| } |
| mark = self.marks[mark.0 as usize].parent; |
| } |
| true |
| } |
| |
| fn default_transparency(&self, mark: Mark) -> Transparency { |
| self.marks[mark.0 as usize].default_transparency |
| } |
| |
| fn modern(&self, ctxt: SyntaxContext) -> SyntaxContext { |
| self.syntax_contexts[ctxt.0 as usize].opaque |
| } |
| |
| fn modern_and_legacy(&self, ctxt: SyntaxContext) -> SyntaxContext { |
| self.syntax_contexts[ctxt.0 as usize].opaque_and_semitransparent |
| } |
| |
| fn outer(&self, ctxt: SyntaxContext) -> Mark { |
| self.syntax_contexts[ctxt.0 as usize].outer_mark |
| } |
| |
| fn transparency(&self, ctxt: SyntaxContext) -> Transparency { |
| self.syntax_contexts[ctxt.0 as usize].transparency |
| } |
| |
| fn prev_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext { |
| self.syntax_contexts[ctxt.0 as usize].prev_ctxt |
| } |
| |
| fn remove_mark(&self, ctxt: &mut SyntaxContext) -> Mark { |
| let outer_mark = self.syntax_contexts[ctxt.0 as usize].outer_mark; |
| *ctxt = self.prev_ctxt(*ctxt); |
| outer_mark |
| } |
| |
| fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(Mark, Transparency)> { |
| let mut marks = Vec::new(); |
| while ctxt != SyntaxContext::empty() { |
| let outer_mark = self.outer(ctxt); |
| let transparency = self.transparency(ctxt); |
| let prev_ctxt = self.prev_ctxt(ctxt); |
| marks.push((outer_mark, transparency)); |
| ctxt = prev_ctxt; |
| } |
| marks.reverse(); |
| marks |
| } |
| |
| fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span { |
| while span.ctxt() != crate::NO_EXPANSION && span.ctxt() != to { |
| if let Some(info) = self.expn_info(self.outer(span.ctxt())) { |
| span = info.call_site; |
| } else { |
| break; |
| } |
| } |
| span |
| } |
| |
| fn adjust(&self, ctxt: &mut SyntaxContext, expansion: Mark) -> Option<Mark> { |
| let mut scope = None; |
| while !self.is_descendant_of(expansion, self.outer(*ctxt)) { |
| scope = Some(self.remove_mark(ctxt)); |
| } |
| scope |
| } |
| |
| fn apply_mark(&mut self, ctxt: SyntaxContext, mark: Mark) -> SyntaxContext { |
| assert_ne!(mark, Mark::root()); |
| self.apply_mark_with_transparency(ctxt, mark, self.default_transparency(mark)) |
| } |
| |
| fn apply_mark_with_transparency(&mut self, ctxt: SyntaxContext, mark: Mark, |
| transparency: Transparency) -> SyntaxContext { |
| assert_ne!(mark, Mark::root()); |
| if transparency == Transparency::Opaque { |
| return self.apply_mark_internal(ctxt, mark, transparency); |
| } |
| |
| let call_site_ctxt = |
| self.expn_info(mark).map_or(SyntaxContext::empty(), |info| info.call_site.ctxt()); |
| let mut call_site_ctxt = if transparency == Transparency::SemiTransparent { |
| self.modern(call_site_ctxt) |
| } else { |
| self.modern_and_legacy(call_site_ctxt) |
| }; |
| |
| if call_site_ctxt == SyntaxContext::empty() { |
| return self.apply_mark_internal(ctxt, mark, transparency); |
| } |
| |
| // Otherwise, `mark` 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/run-pass/hygiene/legacy_interaction.rs`. |
| for (mark, transparency) in self.marks(ctxt) { |
| call_site_ctxt = self.apply_mark_internal(call_site_ctxt, mark, transparency); |
| } |
| self.apply_mark_internal(call_site_ctxt, mark, transparency) |
| } |
| |
| fn apply_mark_internal(&mut self, ctxt: SyntaxContext, mark: Mark, transparency: Transparency) |
| -> SyntaxContext { |
| let syntax_contexts = &mut self.syntax_contexts; |
| let mut opaque = syntax_contexts[ctxt.0 as usize].opaque; |
| let mut opaque_and_semitransparent = |
| syntax_contexts[ctxt.0 as usize].opaque_and_semitransparent; |
| |
| if transparency >= Transparency::Opaque { |
| let prev_ctxt = opaque; |
| opaque = *self.markings.entry((prev_ctxt, mark, transparency)).or_insert_with(|| { |
| let new_opaque = SyntaxContext(syntax_contexts.len() as u32); |
| syntax_contexts.push(SyntaxContextData { |
| outer_mark: mark, |
| transparency, |
| prev_ctxt, |
| opaque: new_opaque, |
| opaque_and_semitransparent: new_opaque, |
| dollar_crate_name: kw::DollarCrate, |
| }); |
| new_opaque |
| }); |
| } |
| |
| if transparency >= Transparency::SemiTransparent { |
| let prev_ctxt = opaque_and_semitransparent; |
| opaque_and_semitransparent = |
| *self.markings.entry((prev_ctxt, mark, transparency)).or_insert_with(|| { |
| let new_opaque_and_semitransparent = |
| SyntaxContext(syntax_contexts.len() as u32); |
| syntax_contexts.push(SyntaxContextData { |
| outer_mark: mark, |
| transparency, |
| prev_ctxt, |
| opaque, |
| opaque_and_semitransparent: new_opaque_and_semitransparent, |
| dollar_crate_name: kw::DollarCrate, |
| }); |
| new_opaque_and_semitransparent |
| }); |
| } |
| |
| let prev_ctxt = ctxt; |
| *self.markings.entry((prev_ctxt, mark, transparency)).or_insert_with(|| { |
| let new_opaque_and_semitransparent_and_transparent = |
| SyntaxContext(syntax_contexts.len() as u32); |
| syntax_contexts.push(SyntaxContextData { |
| outer_mark: mark, |
| transparency, |
| prev_ctxt, |
| opaque, |
| opaque_and_semitransparent, |
| dollar_crate_name: kw::DollarCrate, |
| }); |
| new_opaque_and_semitransparent_and_transparent |
| }) |
| } |
| } |
| |
| pub fn clear_markings() { |
| HygieneData::with(|data| data.markings = FxHashMap::default()); |
| } |
| |
| pub fn walk_chain(span: Span, to: SyntaxContext) -> Span { |
| HygieneData::with(|data| data.walk_chain(span, to)) |
| } |
| |
| impl SyntaxContext { |
| #[inline] |
| pub const fn empty() -> Self { |
| SyntaxContext(0) |
| } |
| |
| #[inline] |
| crate fn as_u32(self) -> u32 { |
| self.0 |
| } |
| |
| #[inline] |
| crate fn from_u32(raw: u32) -> SyntaxContext { |
| SyntaxContext(raw) |
| } |
| |
| // Allocate a new SyntaxContext with the given ExpnInfo. This is used when |
| // deserializing Spans from the incr. comp. cache. |
| // FIXME(mw): This method does not restore MarkData::parent or |
| // SyntaxContextData::prev_ctxt or SyntaxContextData::opaque. These things |
| // don't seem to be used after HIR lowering, so everything should be fine |
| // as long as incremental compilation does not kick in before that. |
| pub fn allocate_directly(expansion_info: ExpnInfo) -> Self { |
| HygieneData::with(|data| { |
| data.marks.push(MarkData { |
| parent: Mark::root(), |
| default_transparency: Transparency::SemiTransparent, |
| expn_info: Some(expansion_info), |
| }); |
| |
| let mark = Mark(data.marks.len() as u32 - 1); |
| |
| data.syntax_contexts.push(SyntaxContextData { |
| outer_mark: mark, |
| transparency: Transparency::SemiTransparent, |
| prev_ctxt: SyntaxContext::empty(), |
| opaque: SyntaxContext::empty(), |
| opaque_and_semitransparent: SyntaxContext::empty(), |
| dollar_crate_name: kw::DollarCrate, |
| }); |
| SyntaxContext(data.syntax_contexts.len() as u32 - 1) |
| }) |
| } |
| |
| /// Extend a syntax context with a given mark and default transparency for that mark. |
| pub fn apply_mark(self, mark: Mark) -> SyntaxContext { |
| HygieneData::with(|data| data.apply_mark(self, mark)) |
| } |
| |
| /// Extend a syntax context with a given mark and transparency |
| pub fn apply_mark_with_transparency(self, mark: Mark, transparency: Transparency) |
| -> SyntaxContext { |
| HygieneData::with(|data| data.apply_mark_with_transparency(self, mark, 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: |
| /// |
| /// ```rust |
| /// 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) -> Mark { |
| HygieneData::with(|data| data.remove_mark(self)) |
| } |
| |
| pub fn marks(self) -> Vec<(Mark, 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 |
| /// 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 `Mark` from `m`. |
| /// pub fn $f() {} // `$f`'s `SyntaxContext` is empty. |
| /// } |
| /// foo::f(); // `f`'s `SyntaxContext` has a single `Mark` 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 `Mark` 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::$f`. |
| /// } |
| /// ``` |
| /// This returns the expansion whose definition scope we use to privacy check the resolution, |
| /// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope). |
| pub fn adjust(&mut self, expansion: Mark) -> Option<Mark> { |
| HygieneData::with(|data| data.adjust(self, expansion)) |
| } |
| |
| /// Like `SyntaxContext::adjust`, but also modernizes `self`. |
| pub fn modernize_and_adjust(&mut self, expansion: Mark) -> Option<Mark> { |
| HygieneData::with(|data| { |
| *self = data.modern(*self); |
| data.adjust(self, expansion) |
| }) |
| } |
| |
| /// Adjust this context for resolution in a scope created by the given expansion |
| /// via a glob import with the given `SyntaxContext`. |
| /// For example: |
| /// |
| /// ```rust |
| /// m!(f); |
| /// macro m($i:ident) { |
| /// mod foo { |
| /// pub fn f() {} // `f`'s `SyntaxContext` has a single `Mark` 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, expansion: Mark, glob_span: Span) -> Option<Option<Mark>> { |
| HygieneData::with(|data| { |
| let mut scope = None; |
| let mut glob_ctxt = data.modern(glob_span.ctxt()); |
| while !data.is_descendant_of(expansion, data.outer(glob_ctxt)) { |
| scope = Some(data.remove_mark(&mut glob_ctxt)); |
| if data.remove_mark(self) != scope.unwrap() { |
| return None; |
| } |
| } |
| if data.adjust(self, expansion).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, expansion: Mark, glob_span: Span) |
| -> Option<Option<Mark>> { |
| HygieneData::with(|data| { |
| if data.adjust(self, expansion).is_some() { |
| return None; |
| } |
| |
| let mut glob_ctxt = data.modern(glob_span.ctxt()); |
| let mut marks = Vec::new(); |
| while !data.is_descendant_of(expansion, data.outer(glob_ctxt)) { |
| marks.push(data.remove_mark(&mut glob_ctxt)); |
| } |
| |
| let scope = marks.last().cloned(); |
| while let Some(mark) = marks.pop() { |
| *self = data.apply_mark(*self, mark); |
| } |
| Some(scope) |
| }) |
| } |
| |
| pub fn hygienic_eq(self, other: SyntaxContext, mark: Mark) -> bool { |
| HygieneData::with(|data| { |
| let mut self_modern = data.modern(self); |
| data.adjust(&mut self_modern, mark); |
| self_modern == data.modern(other) |
| }) |
| } |
| |
| #[inline] |
| pub fn modern(self) -> SyntaxContext { |
| HygieneData::with(|data| data.modern(self)) |
| } |
| |
| #[inline] |
| pub fn modern_and_legacy(self) -> SyntaxContext { |
| HygieneData::with(|data| data.modern_and_legacy(self)) |
| } |
| |
| #[inline] |
| pub fn outer(self) -> Mark { |
| HygieneData::with(|data| data.outer(self)) |
| } |
| |
| /// `ctxt.outer_expn_info()` is equivalent to but faster than |
| /// `ctxt.outer().expn_info()`. |
| #[inline] |
| pub fn outer_expn_info(self) -> Option<ExpnInfo> { |
| HygieneData::with(|data| data.expn_info(data.outer(self))) |
| } |
| |
| /// `ctxt.outer_and_expn_info()` is equivalent to but faster than |
| /// `{ let outer = ctxt.outer(); (outer, outer.expn_info()) }`. |
| #[inline] |
| pub fn outer_and_expn_info(self) -> (Mark, Option<ExpnInfo>) { |
| HygieneData::with(|data| { |
| let outer = data.outer(self); |
| (outer, data.expn_info(outer)) |
| }) |
| } |
| |
| pub fn dollar_crate_name(self) -> Symbol { |
| HygieneData::with(|data| data.syntax_contexts[self.0 as usize].dollar_crate_name) |
| } |
| |
| pub fn set_dollar_crate_name(self, dollar_crate_name: Symbol) { |
| HygieneData::with(|data| { |
| let prev_dollar_crate_name = mem::replace( |
| &mut data.syntax_contexts[self.0 as usize].dollar_crate_name, dollar_crate_name |
| ); |
| assert!(dollar_crate_name == prev_dollar_crate_name || |
| prev_dollar_crate_name == kw::DollarCrate, |
| "$crate name is reset for a syntax context"); |
| }) |
| } |
| } |
| |
| impl fmt::Debug for SyntaxContext { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(f, "#{}", self.0) |
| } |
| } |
| |
| /// Extra information for tracking spans of macro and syntax sugar expansion |
| #[derive(Clone, Hash, Debug, RustcEncodable, RustcDecodable)] |
| pub struct ExpnInfo { |
| /// The location of the actual macro invocation or syntax sugar , e.g. |
| /// `let x = foo!();` or `if let Some(y) = x {}` |
| /// |
| /// This may recursively refer to other macro invocations, e.g., if |
| /// `foo!()` invoked `bar!()` internally, and there was an |
| /// expression inside `bar!`; the call_site of the expression in |
| /// the expansion would point to the `bar!` invocation; that |
| /// call_site span would have its own ExpnInfo, with the call_site |
| /// pointing to the `foo!` invocation. |
| pub call_site: Span, |
| /// The span of the macro definition itself. The macro may not |
| /// have a sensible definition span (e.g., something defined |
| /// completely inside libsyntax) in which case this is None. |
| /// This span serves only informational purpose and is not used for resolution. |
| pub def_site: Option<Span>, |
| /// The format with which the macro was invoked. |
| pub format: ExpnFormat, |
| /// List of #[unstable]/feature-gated features that the macro is allowed to use |
| /// internally without forcing the whole crate to opt-in |
| /// to them. |
| pub allow_internal_unstable: Option<Lrc<[Symbol]>>, |
| /// Whether the macro is allowed to use `unsafe` internally |
| /// even if the user crate has `#![forbid(unsafe_code)]`. |
| pub allow_internal_unsafe: bool, |
| /// Enables the macro helper hack (`ident!(...)` -> `$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 source of expansion. |
| #[derive(Clone, Hash, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)] |
| pub enum ExpnFormat { |
| /// e.g., #[derive(...)] <item> |
| MacroAttribute(Symbol), |
| /// e.g., `format!()` |
| MacroBang(Symbol), |
| /// Desugaring done by the compiler during HIR lowering. |
| CompilerDesugaring(CompilerDesugaringKind) |
| } |
| |
| impl ExpnFormat { |
| pub fn name(&self) -> Symbol { |
| match *self { |
| ExpnFormat::MacroBang(name) | ExpnFormat::MacroAttribute(name) => name, |
| ExpnFormat::CompilerDesugaring(kind) => kind.name(), |
| } |
| } |
| } |
| |
| /// The kind of compiler desugaring. |
| #[derive(Clone, Copy, Hash, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)] |
| pub enum CompilerDesugaringKind { |
| /// 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`. |
| IfTemporary, |
| QuestionMark, |
| TryBlock, |
| /// Desugaring of an `impl Trait` in return type position |
| /// to an `existential type Foo: Trait;` and replacing the |
| /// `impl Trait` with `Foo`. |
| ExistentialType, |
| Async, |
| Await, |
| ForLoop, |
| } |
| |
| impl CompilerDesugaringKind { |
| pub fn name(self) -> Symbol { |
| Symbol::intern(match self { |
| CompilerDesugaringKind::IfTemporary => "if", |
| CompilerDesugaringKind::Async => "async", |
| CompilerDesugaringKind::Await => "await", |
| CompilerDesugaringKind::QuestionMark => "?", |
| CompilerDesugaringKind::TryBlock => "try block", |
| CompilerDesugaringKind::ExistentialType => "existential type", |
| CompilerDesugaringKind::ForLoop => "for loop", |
| }) |
| } |
| } |
| |
| impl Encodable for SyntaxContext { |
| fn encode<E: Encoder>(&self, _: &mut E) -> Result<(), E::Error> { |
| Ok(()) // FIXME(jseyfried) intercrate hygiene |
| } |
| } |
| |
| impl Decodable for SyntaxContext { |
| fn decode<D: Decoder>(_: &mut D) -> Result<SyntaxContext, D::Error> { |
| Ok(SyntaxContext::empty()) // FIXME(jseyfried) intercrate hygiene |
| } |
| } |
