1 //! Machinery for hygienic macros.
3 //! Inspired by Matthew Flatt et al., “Macros That Work Together: Compile-Time Bindings, Partial
4 //! Expansion, and Definition Contexts,” *Journal of Functional Programming* 22, no. 2
5 //! (March 1, 2012): 181–216, <https://doi.org/10.1017/S0956796812000093>.
7 // Hygiene data is stored in a global variable and accessed via TLS, which
8 // means that accesses are somewhat expensive. (`HygieneData::with`
9 // encapsulates a single access.) Therefore, on hot code paths it is worth
10 // ensuring that multiple HygieneData accesses are combined into a single
11 // `HygieneData::with`.
13 // This explains why `HygieneData`, `SyntaxContext` and `ExpnId` have interfaces
14 // with a certain amount of redundancy in them. For example,
15 // `SyntaxContext::outer_expn_data` combines `SyntaxContext::outer` and
16 // `ExpnId::expn_data` so that two `HygieneData` accesses can be performed within
17 // a single `HygieneData::with` call.
19 // It also explains why many functions appear in `HygieneData` and again in
20 // `SyntaxContext` or `ExpnId`. For example, `HygieneData::outer` and
21 // `SyntaxContext::outer` do the same thing, but the former is for use within a
22 // `HygieneData::with` call while the latter is for use outside such a call.
23 // When modifying this file it is important to understand this distinction,
24 // because getting it wrong can lead to nested `HygieneData::with` calls that
25 // trigger runtime aborts. (Fortunately these are obvious and easy to fix.)
27 use crate::edition
::Edition
;
28 use crate::symbol
::{kw, sym, Symbol}
;
29 use crate::SESSION_GLOBALS
;
30 use crate::{Span, DUMMY_SP}
;
32 use crate::def_id
::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE}
;
33 use rustc_data_structures
::fx
::{FxHashMap, FxHashSet}
;
34 use rustc_data_structures
::sync
::{Lock, Lrc}
;
35 use rustc_macros
::HashStable_Generic
;
36 use rustc_serialize
::{Decodable, Decoder, Encodable, Encoder}
;
40 /// A `SyntaxContext` represents a chain of pairs `(ExpnId, Transparency)` named "marks".
41 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
42 pub struct SyntaxContext(u32);
44 #[derive(Debug, Encodable, Decodable, Clone)]
45 pub struct SyntaxContextData
{
47 outer_transparency
: Transparency
,
48 parent
: SyntaxContext
,
49 /// This context, but with all transparent and semi-transparent expansions filtered away.
50 opaque
: SyntaxContext
,
51 /// This context, but with all transparent expansions filtered away.
52 opaque_and_semitransparent
: SyntaxContext
,
53 /// Name of the crate to which `$crate` with this context would resolve.
54 dollar_crate_name
: Symbol
,
57 /// A unique ID associated with a macro invocation and expansion.
58 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
59 pub struct ExpnId(u32);
61 /// A property of a macro expansion that determines how identifiers
62 /// produced by that expansion are resolved.
63 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Hash, Debug, Encodable, Decodable)]
64 #[derive(HashStable_Generic)]
65 pub enum Transparency
{
66 /// Identifier produced by a transparent expansion is always resolved at call-site.
67 /// Call-site spans in procedural macros, hygiene opt-out in `macro` should use this.
69 /// Identifier produced by a semi-transparent expansion may be resolved
70 /// either at call-site or at definition-site.
71 /// If it's a local variable, label or `$crate` then it's resolved at def-site.
72 /// Otherwise it's resolved at call-site.
73 /// `macro_rules` macros behave like this, built-in macros currently behave like this too,
74 /// but that's an implementation detail.
76 /// Identifier produced by an opaque expansion is always resolved at definition-site.
77 /// Def-site spans in procedural macros, identifiers from `macro` by default use this.
82 pub fn fresh(expn_data
: Option
<ExpnData
>) -> Self {
83 HygieneData
::with(|data
| data
.fresh_expn(expn_data
))
86 /// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
88 pub fn root() -> Self {
93 pub fn as_u32(self) -> u32 {
98 pub fn from_u32(raw
: u32) -> ExpnId
{
103 pub fn expn_data(self) -> ExpnData
{
104 HygieneData
::with(|data
| data
.expn_data(self).clone())
108 pub fn set_expn_data(self, mut expn_data
: ExpnData
) {
109 HygieneData
::with(|data
| {
110 let old_expn_data
= &mut data
.expn_data
[self.0 as usize];
111 assert
!(old_expn_data
.is_none(), "expansion data is reset for an expansion ID");
112 expn_data
.orig_id
.replace(self.as_u32()).expect_none("orig_id should be None");
113 *old_expn_data
= Some(expn_data
);
117 pub fn is_descendant_of(self, ancestor
: ExpnId
) -> bool
{
118 HygieneData
::with(|data
| data
.is_descendant_of(self, ancestor
))
121 /// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
122 /// `expn_id.is_descendant_of(ctxt.outer_expn())`.
123 pub fn outer_expn_is_descendant_of(self, ctxt
: SyntaxContext
) -> bool
{
124 HygieneData
::with(|data
| data
.is_descendant_of(self, data
.outer_expn(ctxt
)))
127 /// Returns span for the macro which originally caused this expansion to happen.
129 /// Stops backtracing at include! boundary.
130 pub fn expansion_cause(mut self) -> Option
<Span
> {
131 let mut last_macro
= None
;
133 let expn_data
= self.expn_data();
134 // Stop going up the backtrace once include! is encountered
135 if expn_data
.is_root()
136 || expn_data
.kind
== ExpnKind
::Macro(MacroKind
::Bang
, sym
::include
)
140 self = expn_data
.call_site
.ctxt().outer_expn();
141 last_macro
= Some(expn_data
.call_site
);
148 pub struct HygieneData
{
149 /// Each expansion should have an associated expansion data, but sometimes there's a delay
150 /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
151 /// first and then resolved later), so we use an `Option` here.
152 expn_data
: Vec
<Option
<ExpnData
>>,
153 syntax_context_data
: Vec
<SyntaxContextData
>,
154 syntax_context_map
: FxHashMap
<(SyntaxContext
, ExpnId
, Transparency
), SyntaxContext
>,
158 crate fn new(edition
: Edition
) -> Self {
159 let mut root_data
= ExpnData
::default(
163 Some(DefId
::local(CRATE_DEF_INDEX
)),
165 root_data
.orig_id
= Some(0);
168 expn_data
: vec
![Some(root_data
)],
169 syntax_context_data
: vec
![SyntaxContextData
{
170 outer_expn
: ExpnId
::root(),
171 outer_transparency
: Transparency
::Opaque
,
172 parent
: SyntaxContext(0),
173 opaque
: SyntaxContext(0),
174 opaque_and_semitransparent
: SyntaxContext(0),
175 dollar_crate_name
: kw
::DollarCrate
,
177 syntax_context_map
: FxHashMap
::default(),
181 pub fn with
<T
, F
: FnOnce(&mut HygieneData
) -> T
>(f
: F
) -> T
{
182 SESSION_GLOBALS
.with(|session_globals
| f(&mut *session_globals
.hygiene_data
.borrow_mut()))
185 fn fresh_expn(&mut self, mut expn_data
: Option
<ExpnData
>) -> ExpnId
{
186 let raw_id
= self.expn_data
.len() as u32;
187 if let Some(data
) = expn_data
.as_mut() {
188 data
.orig_id
.replace(raw_id
).expect_none("orig_id should be None");
190 self.expn_data
.push(expn_data
);
194 fn expn_data(&self, expn_id
: ExpnId
) -> &ExpnData
{
195 self.expn_data
[expn_id
.0 as usize].as_ref().expect("no expansion data for an expansion ID")
198 fn is_descendant_of(&self, mut expn_id
: ExpnId
, ancestor
: ExpnId
) -> bool
{
199 while expn_id
!= ancestor
{
200 if expn_id
== ExpnId
::root() {
203 expn_id
= self.expn_data(expn_id
).parent
;
208 fn normalize_to_macros_2_0(&self, ctxt
: SyntaxContext
) -> SyntaxContext
{
209 self.syntax_context_data
[ctxt
.0 as usize].opaque
212 fn normalize_to_macro_rules(&self, ctxt
: SyntaxContext
) -> SyntaxContext
{
213 self.syntax_context_data
[ctxt
.0 as usize].opaque_and_semitransparent
216 fn outer_expn(&self, ctxt
: SyntaxContext
) -> ExpnId
{
217 self.syntax_context_data
[ctxt
.0 as usize].outer_expn
220 fn outer_mark(&self, ctxt
: SyntaxContext
) -> (ExpnId
, Transparency
) {
221 let data
= &self.syntax_context_data
[ctxt
.0 as usize];
222 (data
.outer_expn
, data
.outer_transparency
)
225 fn parent_ctxt(&self, ctxt
: SyntaxContext
) -> SyntaxContext
{
226 self.syntax_context_data
[ctxt
.0 as usize].parent
229 fn remove_mark(&self, ctxt
: &mut SyntaxContext
) -> (ExpnId
, Transparency
) {
230 let outer_mark
= self.outer_mark(*ctxt
);
231 *ctxt
= self.parent_ctxt(*ctxt
);
235 fn marks(&self, mut ctxt
: SyntaxContext
) -> Vec
<(ExpnId
, Transparency
)> {
236 let mut marks
= Vec
::new();
237 while ctxt
!= SyntaxContext
::root() {
238 debug
!("marks: getting parent of {:?}", ctxt
);
239 marks
.push(self.outer_mark(ctxt
));
240 ctxt
= self.parent_ctxt(ctxt
);
246 fn walk_chain(&self, mut span
: Span
, to
: SyntaxContext
) -> Span
{
247 debug
!("walk_chain({:?}, {:?})", span
, to
);
248 debug
!("walk_chain: span ctxt = {:?}", span
.ctxt());
249 while span
.from_expansion() && span
.ctxt() != to
{
250 let outer_expn
= self.outer_expn(span
.ctxt());
251 debug
!("walk_chain({:?}): outer_expn={:?}", span
, outer_expn
);
252 let expn_data
= self.expn_data(outer_expn
);
253 debug
!("walk_chain({:?}): expn_data={:?}", span
, expn_data
);
254 span
= expn_data
.call_site
;
259 fn adjust(&self, ctxt
: &mut SyntaxContext
, expn_id
: ExpnId
) -> Option
<ExpnId
> {
260 let mut scope
= None
;
261 while !self.is_descendant_of(expn_id
, self.outer_expn(*ctxt
)) {
262 scope
= Some(self.remove_mark(ctxt
).0);
271 transparency
: Transparency
,
273 assert_ne
!(expn_id
, ExpnId
::root());
274 if transparency
== Transparency
::Opaque
{
275 return self.apply_mark_internal(ctxt
, expn_id
, transparency
);
278 let call_site_ctxt
= self.expn_data(expn_id
).call_site
.ctxt();
279 let mut call_site_ctxt
= if transparency
== Transparency
::SemiTransparent
{
280 self.normalize_to_macros_2_0(call_site_ctxt
)
282 self.normalize_to_macro_rules(call_site_ctxt
)
285 if call_site_ctxt
== SyntaxContext
::root() {
286 return self.apply_mark_internal(ctxt
, expn_id
, transparency
);
289 // Otherwise, `expn_id` is a macros 1.0 definition and the call site is in a
290 // macros 2.0 expansion, i.e., a macros 1.0 invocation is in a macros 2.0 definition.
292 // In this case, the tokens from the macros 1.0 definition inherit the hygiene
293 // at their invocation. That is, we pretend that the macros 1.0 definition
294 // was defined at its invocation (i.e., inside the macros 2.0 definition)
295 // so that the macros 2.0 definition remains hygienic.
297 // See the example at `test/ui/hygiene/legacy_interaction.rs`.
298 for (expn_id
, transparency
) in self.marks(ctxt
) {
299 call_site_ctxt
= self.apply_mark_internal(call_site_ctxt
, expn_id
, transparency
);
301 self.apply_mark_internal(call_site_ctxt
, expn_id
, transparency
)
304 fn apply_mark_internal(
308 transparency
: Transparency
,
310 let syntax_context_data
= &mut self.syntax_context_data
;
311 let mut opaque
= syntax_context_data
[ctxt
.0 as usize].opaque
;
312 let mut opaque_and_semitransparent
=
313 syntax_context_data
[ctxt
.0 as usize].opaque_and_semitransparent
;
315 if transparency
>= Transparency
::Opaque
{
319 .entry((parent
, expn_id
, transparency
))
321 let new_opaque
= SyntaxContext(syntax_context_data
.len() as u32);
322 syntax_context_data
.push(SyntaxContextData
{
324 outer_transparency
: transparency
,
327 opaque_and_semitransparent
: new_opaque
,
328 dollar_crate_name
: kw
::DollarCrate
,
334 if transparency
>= Transparency
::SemiTransparent
{
335 let parent
= opaque_and_semitransparent
;
336 opaque_and_semitransparent
= *self
338 .entry((parent
, expn_id
, transparency
))
340 let new_opaque_and_semitransparent
=
341 SyntaxContext(syntax_context_data
.len() as u32);
342 syntax_context_data
.push(SyntaxContextData
{
344 outer_transparency
: transparency
,
347 opaque_and_semitransparent
: new_opaque_and_semitransparent
,
348 dollar_crate_name
: kw
::DollarCrate
,
350 new_opaque_and_semitransparent
355 *self.syntax_context_map
.entry((parent
, expn_id
, transparency
)).or_insert_with(|| {
356 let new_opaque_and_semitransparent_and_transparent
=
357 SyntaxContext(syntax_context_data
.len() as u32);
358 syntax_context_data
.push(SyntaxContextData
{
360 outer_transparency
: transparency
,
363 opaque_and_semitransparent
,
364 dollar_crate_name
: kw
::DollarCrate
,
366 new_opaque_and_semitransparent_and_transparent
371 pub fn clear_syntax_context_map() {
372 HygieneData
::with(|data
| data
.syntax_context_map
= FxHashMap
::default());
375 pub fn walk_chain(span
: Span
, to
: SyntaxContext
) -> Span
{
376 HygieneData
::with(|data
| data
.walk_chain(span
, to
))
379 pub fn update_dollar_crate_names(mut get_name
: impl FnMut(SyntaxContext
) -> Symbol
) {
380 // The new contexts that need updating are at the end of the list and have `$crate` as a name.
381 let (len
, to_update
) = HygieneData
::with(|data
| {
383 data
.syntax_context_data
.len(),
384 data
.syntax_context_data
387 .take_while(|scdata
| scdata
.dollar_crate_name
== kw
::DollarCrate
)
391 // The callback must be called from outside of the `HygieneData` lock,
392 // since it will try to acquire it too.
393 let range_to_update
= len
- to_update
..len
;
395 range_to_update
.clone().map(|idx
| get_name(SyntaxContext
::from_u32(idx
as u32))).collect();
396 HygieneData
::with(|data
| {
397 range_to_update
.zip(names
.into_iter()).for_each(|(idx
, name
)| {
398 data
.syntax_context_data
[idx
].dollar_crate_name
= name
;
403 pub fn debug_hygiene_data(verbose
: bool
) -> String
{
404 HygieneData
::with(|data
| {
406 format
!("{:#?}", data
)
408 let mut s
= String
::from("");
409 s
.push_str("Expansions:");
410 data
.expn_data
.iter().enumerate().for_each(|(id
, expn_info
)| {
411 let expn_info
= expn_info
.as_ref().expect("no expansion data for an expansion ID");
413 "\n{}: parent: {:?}, call_site_ctxt: {:?}, def_site_ctxt: {:?}, kind: {:?}",
416 expn_info
.call_site
.ctxt(),
417 expn_info
.def_site
.ctxt(),
421 s
.push_str("\n\nSyntaxContexts:");
422 data
.syntax_context_data
.iter().enumerate().for_each(|(id
, ctxt
)| {
424 "\n#{}: parent: {:?}, outer_mark: ({:?}, {:?})",
425 id
, ctxt
.parent
, ctxt
.outer_expn
, ctxt
.outer_transparency
,
435 pub const fn root() -> Self {
440 crate fn as_u32(self) -> u32 {
445 crate fn from_u32(raw
: u32) -> SyntaxContext
{
449 /// Extend a syntax context with a given expansion and transparency.
450 crate fn apply_mark(self, expn_id
: ExpnId
, transparency
: Transparency
) -> SyntaxContext
{
451 HygieneData
::with(|data
| data
.apply_mark(self, expn_id
, transparency
))
454 /// Pulls a single mark off of the syntax context. This effectively moves the
455 /// context up one macro definition level. That is, if we have a nested macro
456 /// definition as follows:
466 /// and we have a SyntaxContext that is referring to something declared by an invocation
467 /// of g (call it g1), calling remove_mark will result in the SyntaxContext for the
468 /// invocation of f that created g1.
469 /// Returns the mark that was removed.
470 pub fn remove_mark(&mut self) -> ExpnId
{
471 HygieneData
::with(|data
| data
.remove_mark(self).0)
474 pub fn marks(self) -> Vec
<(ExpnId
, Transparency
)> {
475 HygieneData
::with(|data
| data
.marks(self))
478 /// Adjust this context for resolution in a scope created by the given expansion.
479 /// For example, consider the following three resolutions of `f`:
482 /// mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
484 /// macro m($f:ident) {
486 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
487 /// pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
489 /// foo::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
490 /// //^ Since `mod foo` is outside this expansion, `adjust` removes the mark from `f`,
491 /// //| and it resolves to `::foo::f`.
492 /// bar::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
493 /// //^ Since `mod bar` not outside this expansion, `adjust` does not change `f`,
494 /// //| and it resolves to `::bar::f`.
495 /// bar::$f(); // `f`'s `SyntaxContext` is empty.
496 /// //^ Since `mod bar` is not outside this expansion, `adjust` does not change `$f`,
497 /// //| and it resolves to `::bar::$f`.
500 /// This returns the expansion whose definition scope we use to privacy check the resolution,
501 /// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope).
502 pub fn adjust(&mut self, expn_id
: ExpnId
) -> Option
<ExpnId
> {
503 HygieneData
::with(|data
| data
.adjust(self, expn_id
))
506 /// Like `SyntaxContext::adjust`, but also normalizes `self` to macros 2.0.
507 pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id
: ExpnId
) -> Option
<ExpnId
> {
508 HygieneData
::with(|data
| {
509 *self = data
.normalize_to_macros_2_0(*self);
510 data
.adjust(self, expn_id
)
514 /// Adjust this context for resolution in a scope created by the given expansion
515 /// via a glob import with the given `SyntaxContext`.
520 /// macro m($i:ident) {
522 /// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
523 /// pub fn $i() {} // `$i`'s `SyntaxContext` is empty.
526 /// macro n($j:ident) {
528 /// f(); // `f`'s `SyntaxContext` has a mark from `m` and a mark from `n`
529 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::f`.
530 /// $i(); // `$i`'s `SyntaxContext` has a mark from `n`
531 /// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::$i`.
532 /// $j(); // `$j`'s `SyntaxContext` has a mark from `m`
533 /// //^ This cannot be glob-adjusted, so this is a resolution error.
537 /// This returns `None` if the context cannot be glob-adjusted.
538 /// Otherwise, it returns the scope to use when privacy checking (see `adjust` for details).
539 pub fn glob_adjust(&mut self, expn_id
: ExpnId
, glob_span
: Span
) -> Option
<Option
<ExpnId
>> {
540 HygieneData
::with(|data
| {
541 let mut scope
= None
;
542 let mut glob_ctxt
= data
.normalize_to_macros_2_0(glob_span
.ctxt());
543 while !data
.is_descendant_of(expn_id
, data
.outer_expn(glob_ctxt
)) {
544 scope
= Some(data
.remove_mark(&mut glob_ctxt
).0);
545 if data
.remove_mark(self).0 != scope
.unwrap() {
549 if data
.adjust(self, expn_id
).is_some() {
556 /// Undo `glob_adjust` if possible:
559 /// if let Some(privacy_checking_scope) = self.reverse_glob_adjust(expansion, glob_ctxt) {
560 /// assert!(self.glob_adjust(expansion, glob_ctxt) == Some(privacy_checking_scope));
563 pub fn reverse_glob_adjust(
567 ) -> Option
<Option
<ExpnId
>> {
568 HygieneData
::with(|data
| {
569 if data
.adjust(self, expn_id
).is_some() {
573 let mut glob_ctxt
= data
.normalize_to_macros_2_0(glob_span
.ctxt());
574 let mut marks
= Vec
::new();
575 while !data
.is_descendant_of(expn_id
, data
.outer_expn(glob_ctxt
)) {
576 marks
.push(data
.remove_mark(&mut glob_ctxt
));
579 let scope
= marks
.last().map(|mark
| mark
.0);
580 while let Some((expn_id
, transparency
)) = marks
.pop() {
581 *self = data
.apply_mark(*self, expn_id
, transparency
);
587 pub fn hygienic_eq(self, other
: SyntaxContext
, expn_id
: ExpnId
) -> bool
{
588 HygieneData
::with(|data
| {
589 let mut self_normalized
= data
.normalize_to_macros_2_0(self);
590 data
.adjust(&mut self_normalized
, expn_id
);
591 self_normalized
== data
.normalize_to_macros_2_0(other
)
596 pub fn normalize_to_macros_2_0(self) -> SyntaxContext
{
597 HygieneData
::with(|data
| data
.normalize_to_macros_2_0(self))
601 pub fn normalize_to_macro_rules(self) -> SyntaxContext
{
602 HygieneData
::with(|data
| data
.normalize_to_macro_rules(self))
606 pub fn outer_expn(self) -> ExpnId
{
607 HygieneData
::with(|data
| data
.outer_expn(self))
610 /// `ctxt.outer_expn_data()` is equivalent to but faster than
611 /// `ctxt.outer_expn().expn_data()`.
613 pub fn outer_expn_data(self) -> ExpnData
{
614 HygieneData
::with(|data
| data
.expn_data(data
.outer_expn(self)).clone())
618 pub fn outer_mark(self) -> (ExpnId
, Transparency
) {
619 HygieneData
::with(|data
| data
.outer_mark(self))
623 pub fn outer_mark_with_data(self) -> (ExpnId
, Transparency
, ExpnData
) {
624 HygieneData
::with(|data
| {
625 let (expn_id
, transparency
) = data
.outer_mark(self);
626 (expn_id
, transparency
, data
.expn_data(expn_id
).clone())
630 pub fn dollar_crate_name(self) -> Symbol
{
631 HygieneData
::with(|data
| data
.syntax_context_data
[self.0 as usize].dollar_crate_name
)
635 impl fmt
::Debug
for SyntaxContext
{
636 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
637 write
!(f
, "#{}", self.0)
642 /// Creates a fresh expansion with given properties.
643 /// Expansions are normally created by macros, but in some cases expansions are created for
644 /// other compiler-generated code to set per-span properties like allowed unstable features.
645 /// The returned span belongs to the created expansion and has the new properties,
646 /// but its location is inherited from the current span.
647 pub fn fresh_expansion(self, expn_data
: ExpnData
) -> Span
{
648 self.fresh_expansion_with_transparency(expn_data
, Transparency
::Transparent
)
651 pub fn fresh_expansion_with_transparency(
654 transparency
: Transparency
,
656 HygieneData
::with(|data
| {
657 let expn_id
= data
.fresh_expn(Some(expn_data
));
658 self.with_ctxt(data
.apply_mark(SyntaxContext
::root(), expn_id
, transparency
))
663 /// A subset of properties from both macro definition and macro call available through global data.
664 /// Avoid using this if you have access to the original definition or call structures.
665 #[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
666 pub struct ExpnData
{
667 // --- The part unique to each expansion.
668 /// The kind of this expansion - macro or compiler desugaring.
670 /// The expansion that produced this expansion.
672 /// The location of the actual macro invocation or syntax sugar , e.g.
673 /// `let x = foo!();` or `if let Some(y) = x {}`
675 /// This may recursively refer to other macro invocations, e.g., if
676 /// `foo!()` invoked `bar!()` internally, and there was an
677 /// expression inside `bar!`; the call_site of the expression in
678 /// the expansion would point to the `bar!` invocation; that
679 /// call_site span would have its own ExpnData, with the call_site
680 /// pointing to the `foo!` invocation.
683 // --- The part specific to the macro/desugaring definition.
684 // --- It may be reasonable to share this part between expansions with the same definition,
685 // --- but such sharing is known to bring some minor inconveniences without also bringing
686 // --- noticeable perf improvements (PR #62898).
687 /// The span of the macro definition (possibly dummy).
688 /// This span serves only informational purpose and is not used for resolution.
690 /// List of `#[unstable]`/feature-gated features that the macro is allowed to use
691 /// internally without forcing the whole crate to opt-in
693 pub allow_internal_unstable
: Option
<Lrc
<[Symbol
]>>,
694 /// Whether the macro is allowed to use `unsafe` internally
695 /// even if the user crate has `#![forbid(unsafe_code)]`.
696 pub allow_internal_unsafe
: bool
,
697 /// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`)
698 /// for a given macro.
699 pub local_inner_macros
: bool
,
700 /// Edition of the crate in which the macro is defined.
701 pub edition
: Edition
,
702 /// The `DefId` of the macro being invoked,
703 /// if this `ExpnData` corresponds to a macro invocation
704 pub macro_def_id
: Option
<DefId
>,
705 /// The crate that originally created this `ExpnData`. During
706 /// metadata serialization, we only encode `ExpnData`s that were
707 /// created locally - when our serialized metadata is decoded,
708 /// foreign `ExpnId`s will have their `ExpnData` looked up
709 /// from the crate specified by `Crate
711 /// The raw that this `ExpnData` had in its original crate.
712 /// An `ExpnData` can be created before being assigned an `ExpnId`,
713 /// so this might be `None` until `set_expn_data` is called
714 // This is used only for serialization/deserialization purposes:
715 // two `ExpnData`s that differ only in their `orig_id` should
716 // be considered equivalent.
717 #[stable_hasher(ignore)]
718 pub orig_id
: Option
<u32>,
721 // This would require special handling of `orig_id` and `parent`
722 impl !PartialEq
for ExpnData {}
725 /// Constructs expansion data with default properties.
730 macro_def_id
: Option
<DefId
>,
734 parent
: ExpnId
::root(),
737 allow_internal_unstable
: None
,
738 allow_internal_unsafe
: false,
739 local_inner_macros
: false,
747 pub fn allow_unstable(
751 allow_internal_unstable
: Lrc
<[Symbol
]>,
752 macro_def_id
: Option
<DefId
>,
755 allow_internal_unstable
: Some(allow_internal_unstable
),
756 ..ExpnData
::default(kind
, call_site
, edition
, macro_def_id
)
761 pub fn is_root(&self) -> bool
{
762 matches
!(self.kind
, ExpnKind
::Root
)
767 #[derive(Clone, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
769 /// No expansion, aka root expansion. Only `ExpnId::root()` has this kind.
771 /// Expansion produced by a macro.
772 Macro(MacroKind
, Symbol
),
773 /// Transform done by the compiler on the AST.
775 /// Desugaring done by the compiler during HIR lowering.
776 Desugaring(DesugaringKind
),
780 pub fn descr(&self) -> String
{
782 ExpnKind
::Root
=> kw
::PathRoot
.to_string(),
783 ExpnKind
::Macro(macro_kind
, name
) => match macro_kind
{
784 MacroKind
::Bang
=> format
!("{}!", name
),
785 MacroKind
::Attr
=> format
!("#[{}]", name
),
786 MacroKind
::Derive
=> format
!("#[derive({})]", name
),
788 ExpnKind
::AstPass(kind
) => kind
.descr().to_string(),
789 ExpnKind
::Desugaring(kind
) => format
!("desugaring of {}", kind
.descr()),
794 /// The kind of macro invocation or definition.
795 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
796 #[derive(HashStable_Generic)]
798 /// A bang macro `foo!()`.
800 /// An attribute macro `#[foo]`.
802 /// A derive macro `#[derive(Foo)]`
807 pub fn descr(self) -> &'
static str {
809 MacroKind
::Bang
=> "macro",
810 MacroKind
::Attr
=> "attribute macro",
811 MacroKind
::Derive
=> "derive macro",
815 pub fn descr_expected(self) -> &'
static str {
817 MacroKind
::Attr
=> "attribute",
822 pub fn article(self) -> &'
static str {
824 MacroKind
::Attr
=> "an",
830 /// The kind of AST transform.
831 #[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
839 fn descr(self) -> &'
static str {
841 AstPass
::StdImports
=> "standard library imports",
842 AstPass
::TestHarness
=> "test harness",
843 AstPass
::ProcMacroHarness
=> "proc macro harness",
848 /// The kind of compiler desugaring.
849 #[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
850 pub enum DesugaringKind
{
851 /// We desugar `if c { i } else { e }` to `match $ExprKind::Use(c) { true => i, _ => e }`.
852 /// However, we do not want to blame `c` for unreachability but rather say that `i`
853 /// is unreachable. This desugaring kind allows us to avoid blaming `c`.
854 /// This also applies to `while` loops.
858 /// Desugaring of an `impl Trait` in return type position
859 /// to an `type Foo = impl Trait;` and replacing the
860 /// `impl Trait` with `Foo`.
867 /// A location in the desugaring of a `for` loop
868 #[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
869 pub enum ForLoopLoc
{
874 impl DesugaringKind
{
875 /// The description wording should combine well with "desugaring of {}".
876 fn descr(self) -> &'
static str {
878 DesugaringKind
::CondTemporary
=> "`if` or `while` condition",
879 DesugaringKind
::Async
=> "`async` block or function",
880 DesugaringKind
::Await
=> "`await` expression",
881 DesugaringKind
::QuestionMark
=> "operator `?`",
882 DesugaringKind
::TryBlock
=> "`try` block",
883 DesugaringKind
::OpaqueTy
=> "`impl Trait`",
884 DesugaringKind
::ForLoop(_
) => "`for` loop",
890 pub struct HygieneEncodeContext
{
891 /// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
892 /// This is `None` after we finish encoding `SyntaxContexts`, to ensure
893 /// that we don't accidentally try to encode any more `SyntaxContexts`
894 serialized_ctxts
: Lock
<FxHashSet
<SyntaxContext
>>,
895 /// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
896 /// in the most recent 'round' of serializnig. Serializing `SyntaxContextData`
897 /// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
898 /// until we reach a fixed point.
899 latest_ctxts
: Lock
<FxHashSet
<SyntaxContext
>>,
901 serialized_expns
: Lock
<FxHashSet
<ExpnId
>>,
903 latest_expns
: Lock
<FxHashSet
<ExpnId
>>,
906 impl HygieneEncodeContext
{
910 F
: FnMut(&mut T
, u32, &SyntaxContextData
) -> Result
<(), R
>,
911 G
: FnMut(&mut T
, u32, &ExpnData
) -> Result
<(), R
>,
918 // When we serialize a `SyntaxContextData`, we may end up serializing
919 // a `SyntaxContext` that we haven't seen before
920 while !self.latest_ctxts
.lock().is_empty() || !self.latest_expns
.lock().is_empty() {
922 "encode_hygiene: Serializing a round of {:?} SyntaxContextDatas: {:?}",
923 self.latest_ctxts
.lock().len(),
927 // Consume the current round of SyntaxContexts.
928 // Drop the lock() temporary early
929 let latest_ctxts
= { std::mem::take(&mut *self.latest_ctxts.lock()) }
;
931 // It's fine to iterate over a HashMap, because the serialization
932 // of the table that we insert data into doesn't depend on insertion
934 for_all_ctxts_in(latest_ctxts
.into_iter(), |(index
, ctxt
, data
)| {
935 if self.serialized_ctxts
.lock().insert(ctxt
) {
936 encode_ctxt(encoder
, index
, data
)?
;
941 let latest_expns
= { std::mem::take(&mut *self.latest_expns.lock()) }
;
943 for_all_expns_in(latest_expns
.into_iter(), |index
, expn
, data
| {
944 if self.serialized_expns
.lock().insert(expn
) {
945 encode_expn(encoder
, index
, data
)?
;
950 debug
!("encode_hygiene: Done serializing SyntaxContextData");
956 /// Additional information used to assist in decoding hygiene data
957 pub struct HygieneDecodeContext
{
958 // Maps serialized `SyntaxContext` ids to a `SyntaxContext` in the current
959 // global `HygieneData`. When we deserialize a `SyntaxContext`, we need to create
960 // a new id in the global `HygieneData`. This map tracks the ID we end up picking,
961 // so that multiple occurrences of the same serialized id are decoded to the same
963 remapped_ctxts
: Lock
<Vec
<Option
<SyntaxContext
>>>,
964 // The same as `remapepd_ctxts`, but for `ExpnId`s
965 remapped_expns
: Lock
<Vec
<Option
<ExpnId
>>>,
968 pub fn decode_expn_id
<
971 F
: FnOnce(&mut D
, u32) -> Result
<ExpnData
, D
::Error
>,
972 G
: FnOnce(CrateNum
) -> &'a HygieneDecodeContext
,
975 mode
: ExpnDataDecodeMode
<'a
, G
>,
977 ) -> Result
<ExpnId
, D
::Error
> {
978 let index
= u32::decode(d
)?
;
979 let context
= match mode
{
980 ExpnDataDecodeMode
::IncrComp(context
) => context
,
981 ExpnDataDecodeMode
::Metadata(get_context
) => {
982 let krate
= CrateNum
::decode(d
)?
;
987 // Do this after decoding, so that we decode a `CrateNum`
989 if index
== ExpnId
::root().as_u32() {
990 debug
!("decode_expn_id: deserialized root");
991 return Ok(ExpnId
::root());
994 let outer_expns
= &context
.remapped_expns
;
996 // Ensure that the lock() temporary is dropped early
998 if let Some(expn_id
) = outer_expns
.lock().get(index
as usize).copied().flatten() {
1003 // Don't decode the data inside `HygieneData::with`, since we need to recursively decode
1005 let mut expn_data
= decode_data(d
, index
)?
;
1007 let expn_id
= HygieneData
::with(|hygiene_data
| {
1008 let expn_id
= ExpnId(hygiene_data
.expn_data
.len() as u32);
1010 // If we just deserialized an `ExpnData` owned by
1011 // the local crate, its `orig_id` will be stale,
1012 // so we need to update it to its own value.
1013 // This only happens when we deserialize the incremental cache,
1014 // since a crate will never decode its own metadata.
1015 if expn_data
.krate
== LOCAL_CRATE
{
1016 expn_data
.orig_id
= Some(expn_id
.0);
1019 hygiene_data
.expn_data
.push(Some(expn_data
));
1021 let mut expns
= outer_expns
.lock();
1022 let new_len
= index
as usize + 1;
1023 if expns
.len() < new_len
{
1024 expns
.resize(new_len
, None
);
1026 expns
[index
as usize] = Some(expn_id
);
1033 // Decodes `SyntaxContext`, using the provided `HygieneDecodeContext`
1034 // to track which `SyntaxContext`s we have already decoded.
1035 // The provided closure will be invoked to deserialize a `SyntaxContextData`
1036 // if we haven't already seen the id of the `SyntaxContext` we are deserializing.
1037 pub fn decode_syntax_context
<
1039 F
: FnOnce(&mut D
, u32) -> Result
<SyntaxContextData
, D
::Error
>,
1042 context
: &HygieneDecodeContext
,
1044 ) -> Result
<SyntaxContext
, D
::Error
> {
1045 let raw_id
: u32 = Decodable
::decode(d
)?
;
1047 debug
!("decode_syntax_context: deserialized root");
1048 // The root is special
1049 return Ok(SyntaxContext
::root());
1052 let outer_ctxts
= &context
.remapped_ctxts
;
1054 // Ensure that the lock() temporary is dropped early
1056 if let Some(ctxt
) = outer_ctxts
.lock().get(raw_id
as usize).copied().flatten() {
1061 // Allocate and store SyntaxContext id *before* calling the decoder function,
1062 // as the SyntaxContextData may reference itself.
1063 let new_ctxt
= HygieneData
::with(|hygiene_data
| {
1064 let new_ctxt
= SyntaxContext(hygiene_data
.syntax_context_data
.len() as u32);
1065 // Push a dummy SyntaxContextData to ensure that nobody else can get the
1066 // same ID as us. This will be overwritten after call `decode_Data`
1067 hygiene_data
.syntax_context_data
.push(SyntaxContextData
{
1068 outer_expn
: ExpnId
::root(),
1069 outer_transparency
: Transparency
::Transparent
,
1070 parent
: SyntaxContext
::root(),
1071 opaque
: SyntaxContext
::root(),
1072 opaque_and_semitransparent
: SyntaxContext
::root(),
1073 dollar_crate_name
: kw
::Invalid
,
1075 let mut ctxts
= outer_ctxts
.lock();
1076 let new_len
= raw_id
as usize + 1;
1077 if ctxts
.len() < new_len
{
1078 ctxts
.resize(new_len
, None
);
1080 ctxts
[raw_id
as usize] = Some(new_ctxt
);
1085 // Don't try to decode data while holding the lock, since we need to
1086 // be able to recursively decode a SyntaxContext
1087 let mut ctxt_data
= decode_data(d
, raw_id
)?
;
1088 // Reset `dollar_crate_name` so that it will be updated by `update_dollar_crate_names`
1089 // We don't care what the encoding crate set this to - we want to resolve it
1090 // from the perspective of the current compilation session
1091 ctxt_data
.dollar_crate_name
= kw
::DollarCrate
;
1093 // Overwrite the dummy data with our decoded SyntaxContextData
1094 HygieneData
::with(|hygiene_data
| {
1095 let dummy
= std
::mem
::replace(
1096 &mut hygiene_data
.syntax_context_data
[new_ctxt
.as_u32() as usize],
1099 // Make sure nothing weird happening while `decode_data` was running
1100 assert_eq
!(dummy
.dollar_crate_name
, kw
::Invalid
);
1106 pub fn num_syntax_ctxts() -> usize {
1107 HygieneData
::with(|data
| data
.syntax_context_data
.len())
1110 pub fn for_all_ctxts_in
<E
, F
: FnMut((u32, SyntaxContext
, &SyntaxContextData
)) -> Result
<(), E
>>(
1111 ctxts
: impl Iterator
<Item
= SyntaxContext
>,
1113 ) -> Result
<(), E
> {
1114 let all_data
: Vec
<_
> = HygieneData
::with(|data
| {
1115 ctxts
.map(|ctxt
| (ctxt
, data
.syntax_context_data
[ctxt
.0 as usize].clone())).collect()
1117 for (ctxt
, data
) in all_data
.into_iter() {
1118 f((ctxt
.0, ctxt
, &data
))?
;
1123 pub fn for_all_expns_in
<E
, F
: FnMut(u32, ExpnId
, &ExpnData
) -> Result
<(), E
>>(
1124 expns
: impl Iterator
<Item
= ExpnId
>,
1126 ) -> Result
<(), E
> {
1127 let all_data
: Vec
<_
> = HygieneData
::with(|data
| {
1128 expns
.map(|expn
| (expn
, data
.expn_data
[expn
.0 as usize].clone())).collect()
1130 for (expn
, data
) in all_data
.into_iter() {
1131 f(expn
.0, expn
, &data
.unwrap_or_else(|| panic
!("Missing data for {:?}", expn
)))?
;
1136 pub fn for_all_data
<E
, F
: FnMut((u32, SyntaxContext
, &SyntaxContextData
)) -> Result
<(), E
>>(
1138 ) -> Result
<(), E
> {
1139 let all_data
= HygieneData
::with(|data
| data
.syntax_context_data
.clone());
1140 for (i
, data
) in all_data
.into_iter().enumerate() {
1141 f((i
as u32, SyntaxContext(i
as u32), &data
))?
;
1146 impl<E
: Encoder
> Encodable
<E
> for ExpnId
{
1147 default fn encode(&self, _
: &mut E
) -> Result
<(), E
::Error
> {
1148 panic
!("cannot encode `ExpnId` with `{}`", std
::any
::type_name
::<E
>());
1152 impl<D
: Decoder
> Decodable
<D
> for ExpnId
{
1153 default fn decode(_
: &mut D
) -> Result
<Self, D
::Error
> {
1154 panic
!("cannot decode `ExpnId` with `{}`", std
::any
::type_name
::<D
>());
1158 pub fn for_all_expn_data
<E
, F
: FnMut(u32, &ExpnData
) -> Result
<(), E
>>(mut f
: F
) -> Result
<(), E
> {
1159 let all_data
= HygieneData
::with(|data
| data
.expn_data
.clone());
1160 for (i
, data
) in all_data
.into_iter().enumerate() {
1161 f(i
as u32, &data
.unwrap_or_else(|| panic
!("Missing ExpnData!")))?
;
1166 pub fn raw_encode_syntax_context
<E
: Encoder
>(
1167 ctxt
: SyntaxContext
,
1168 context
: &HygieneEncodeContext
,
1170 ) -> Result
<(), E
::Error
> {
1171 if !context
.serialized_ctxts
.lock().contains(&ctxt
) {
1172 context
.latest_ctxts
.lock().insert(ctxt
);
1177 pub fn raw_encode_expn_id
<E
: Encoder
>(
1179 context
: &HygieneEncodeContext
,
1180 mode
: ExpnDataEncodeMode
,
1182 ) -> Result
<(), E
::Error
> {
1183 // Record the fact that we need to serialize the corresponding
1185 let needs_data
= || {
1186 if !context
.serialized_expns
.lock().contains(&expn
) {
1187 context
.latest_expns
.lock().insert(expn
);
1192 ExpnDataEncodeMode
::IncrComp
=> {
1193 // Always serialize the `ExpnData` in incr comp mode
1197 ExpnDataEncodeMode
::Metadata
=> {
1198 let data
= expn
.expn_data();
1199 // We only need to serialize the ExpnData
1200 // if it comes from this crate.
1201 // We currently don't serialize any hygiene information data for
1202 // proc-macro crates: see the `SpecializedEncoder<Span>` impl
1203 // for crate metadata.
1204 if data
.krate
== LOCAL_CRATE
{
1207 data
.orig_id
.expect("Missing orig_id").encode(e
)?
;
1208 data
.krate
.encode(e
)
1213 pub enum ExpnDataEncodeMode
{
1218 pub enum ExpnDataDecodeMode
<'a
, F
: FnOnce(CrateNum
) -> &'a HygieneDecodeContext
> {
1219 IncrComp(&'a HygieneDecodeContext
),
1223 impl<'a
> ExpnDataDecodeMode
<'a
, Box
<dyn FnOnce(CrateNum
) -> &'a HygieneDecodeContext
>> {
1224 pub fn incr_comp(ctxt
: &'a HygieneDecodeContext
) -> Self {
1225 ExpnDataDecodeMode
::IncrComp(ctxt
)
1229 impl<E
: Encoder
> Encodable
<E
> for SyntaxContext
{
1230 default fn encode(&self, _
: &mut E
) -> Result
<(), E
::Error
> {
1231 panic
!("cannot encode `SyntaxContext` with `{}`", std
::any
::type_name
::<E
>());
1235 impl<D
: Decoder
> Decodable
<D
> for SyntaxContext
{
1236 default fn decode(_
: &mut D
) -> Result
<Self, D
::Error
> {
1237 panic
!("cannot decode `SyntaxContext` with `{}`", std
::any
::type_name
::<D
>());