1 //! Parsing and validation of builtin attributes
2
3 use rustc_ast::{self as ast, attr};
4 use rustc_ast::{Attribute, LitKind, MetaItem, MetaItemKind, MetaItemLit, NestedMetaItem, NodeId};
5 use rustc_ast_pretty::pprust;
6 use rustc_feature::{find_gated_cfg, is_builtin_attr_name, Features, GatedCfg};
7 use rustc_macros::HashStable_Generic;
8 use rustc_session::config::ExpectedValues;
9 use rustc_session::lint::builtin::UNEXPECTED_CFGS;
10 use rustc_session::lint::BuiltinLintDiagnostics;
11 use rustc_session::parse::{feature_err, ParseSess};
12 use rustc_session::Session;
13 use rustc_span::hygiene::Transparency;
14 use rustc_span::{symbol::sym, symbol::Symbol, Span};
15 use std::num::NonZeroU32;
16
17 use crate::session_diagnostics::{self, IncorrectReprFormatGenericCause};
18
19 /// The version placeholder that recently stabilized features contain inside the
20 /// `since` field of the `#[stable]` attribute.
21 ///
22 /// For more, see [this pull request](https://github.com/rust-lang/rust/pull/100591).
23 pub const VERSION_PLACEHOLDER: &str = "CURRENT_RUSTC_VERSION";
24
rust_version_symbol() -> Symbol25 pub fn rust_version_symbol() -> Symbol {
26 let version = option_env!("CFG_RELEASE").unwrap_or("<current>");
27 Symbol::intern(&version)
28 }
29
is_builtin_attr(attr: &Attribute) -> bool30 pub fn is_builtin_attr(attr: &Attribute) -> bool {
31 attr.is_doc_comment() || attr.ident().filter(|ident| is_builtin_attr_name(ident.name)).is_some()
32 }
33
34 enum AttrError {
35 MultipleItem(String),
36 UnknownMetaItem(String, &'static [&'static str]),
37 MissingSince,
38 NonIdentFeature,
39 MissingFeature,
40 MultipleStabilityLevels,
41 UnsupportedLiteral(UnsupportedLiteralReason, /* is_bytestr */ bool),
42 }
43
44 pub(crate) enum UnsupportedLiteralReason {
45 Generic,
46 CfgString,
47 DeprecatedString,
48 DeprecatedKvPair,
49 }
50
handle_errors(sess: &ParseSess, span: Span, error: AttrError)51 fn handle_errors(sess: &ParseSess, span: Span, error: AttrError) {
52 match error {
53 AttrError::MultipleItem(item) => {
54 sess.emit_err(session_diagnostics::MultipleItem { span, item });
55 }
56 AttrError::UnknownMetaItem(item, expected) => {
57 sess.emit_err(session_diagnostics::UnknownMetaItem { span, item, expected });
58 }
59 AttrError::MissingSince => {
60 sess.emit_err(session_diagnostics::MissingSince { span });
61 }
62 AttrError::NonIdentFeature => {
63 sess.emit_err(session_diagnostics::NonIdentFeature { span });
64 }
65 AttrError::MissingFeature => {
66 sess.emit_err(session_diagnostics::MissingFeature { span });
67 }
68 AttrError::MultipleStabilityLevels => {
69 sess.emit_err(session_diagnostics::MultipleStabilityLevels { span });
70 }
71 AttrError::UnsupportedLiteral(reason, is_bytestr) => {
72 sess.emit_err(session_diagnostics::UnsupportedLiteral {
73 span,
74 reason,
75 is_bytestr,
76 start_point_span: sess.source_map().start_point(span),
77 });
78 }
79 }
80 }
81
82 #[derive(Copy, Clone, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
83 pub enum InlineAttr {
84 None,
85 Hint,
86 Always,
87 Never,
88 }
89
90 #[derive(Clone, Encodable, Decodable, Debug, PartialEq, Eq, HashStable_Generic)]
91 pub enum InstructionSetAttr {
92 ArmA32,
93 ArmT32,
94 }
95
96 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
97 pub enum OptimizeAttr {
98 None,
99 Speed,
100 Size,
101 }
102
103 /// Represents the following attributes:
104 ///
105 /// - `#[stable]`
106 /// - `#[unstable]`
107 #[derive(Encodable, Decodable, Copy, Clone, Debug, PartialEq, Eq, Hash)]
108 #[derive(HashStable_Generic)]
109 pub struct Stability {
110 pub level: StabilityLevel,
111 pub feature: Symbol,
112 }
113
114 impl Stability {
is_unstable(&self) -> bool115 pub fn is_unstable(&self) -> bool {
116 self.level.is_unstable()
117 }
118
is_stable(&self) -> bool119 pub fn is_stable(&self) -> bool {
120 self.level.is_stable()
121 }
122 }
123
124 /// Represents the `#[rustc_const_unstable]` and `#[rustc_const_stable]` attributes.
125 #[derive(Encodable, Decodable, Copy, Clone, Debug, PartialEq, Eq, Hash)]
126 #[derive(HashStable_Generic)]
127 pub struct ConstStability {
128 pub level: StabilityLevel,
129 pub feature: Symbol,
130 /// whether the function has a `#[rustc_promotable]` attribute
131 pub promotable: bool,
132 }
133
134 impl ConstStability {
is_const_unstable(&self) -> bool135 pub fn is_const_unstable(&self) -> bool {
136 self.level.is_unstable()
137 }
138
is_const_stable(&self) -> bool139 pub fn is_const_stable(&self) -> bool {
140 self.level.is_stable()
141 }
142 }
143
144 /// Represents the `#[rustc_default_body_unstable]` attribute.
145 #[derive(Encodable, Decodable, Copy, Clone, Debug, PartialEq, Eq, Hash)]
146 #[derive(HashStable_Generic)]
147 pub struct DefaultBodyStability {
148 pub level: StabilityLevel,
149 pub feature: Symbol,
150 }
151
152 /// The available stability levels.
153 #[derive(Encodable, Decodable, PartialEq, Copy, Clone, Debug, Eq, Hash)]
154 #[derive(HashStable_Generic)]
155 pub enum StabilityLevel {
156 /// `#[unstable]`
157 Unstable {
158 /// Reason for the current stability level.
159 reason: UnstableReason,
160 /// Relevant `rust-lang/rust` issue.
161 issue: Option<NonZeroU32>,
162 is_soft: bool,
163 /// If part of a feature is stabilized and a new feature is added for the remaining parts,
164 /// then the `implied_by` attribute is used to indicate which now-stable feature previously
165 /// contained a item.
166 ///
167 /// ```pseudo-Rust
168 /// #[unstable(feature = "foo", issue = "...")]
169 /// fn foo() {}
170 /// #[unstable(feature = "foo", issue = "...")]
171 /// fn foobar() {}
172 /// ```
173 ///
174 /// ...becomes...
175 ///
176 /// ```pseudo-Rust
177 /// #[stable(feature = "foo", since = "1.XX.X")]
178 /// fn foo() {}
179 /// #[unstable(feature = "foobar", issue = "...", implied_by = "foo")]
180 /// fn foobar() {}
181 /// ```
182 implied_by: Option<Symbol>,
183 },
184 /// `#[stable]`
185 Stable {
186 /// Rust release which stabilized this feature.
187 since: Symbol,
188 /// Is this item allowed to be referred to on stable, despite being contained in unstable
189 /// modules?
190 allowed_through_unstable_modules: bool,
191 },
192 }
193
194 impl StabilityLevel {
is_unstable(&self) -> bool195 pub fn is_unstable(&self) -> bool {
196 matches!(self, StabilityLevel::Unstable { .. })
197 }
is_stable(&self) -> bool198 pub fn is_stable(&self) -> bool {
199 matches!(self, StabilityLevel::Stable { .. })
200 }
201 }
202
203 #[derive(Encodable, Decodable, PartialEq, Copy, Clone, Debug, Eq, Hash)]
204 #[derive(HashStable_Generic)]
205 pub enum UnstableReason {
206 None,
207 Default,
208 Some(Symbol),
209 }
210
211 impl UnstableReason {
from_opt_reason(reason: Option<Symbol>) -> Self212 fn from_opt_reason(reason: Option<Symbol>) -> Self {
213 // UnstableReason::Default constructed manually
214 match reason {
215 Some(r) => Self::Some(r),
216 None => Self::None,
217 }
218 }
219
to_opt_reason(&self) -> Option<Symbol>220 pub fn to_opt_reason(&self) -> Option<Symbol> {
221 match self {
222 Self::None => None,
223 Self::Default => Some(sym::unstable_location_reason_default),
224 Self::Some(r) => Some(*r),
225 }
226 }
227 }
228
229 /// Collects stability info from `stable`/`unstable`/`rustc_allowed_through_unstable_modules`
230 /// attributes in `attrs`. Returns `None` if no stability attributes are found.
find_stability( sess: &Session, attrs: &[Attribute], item_sp: Span, ) -> Option<(Stability, Span)>231 pub fn find_stability(
232 sess: &Session,
233 attrs: &[Attribute],
234 item_sp: Span,
235 ) -> Option<(Stability, Span)> {
236 let mut stab: Option<(Stability, Span)> = None;
237 let mut allowed_through_unstable_modules = false;
238
239 for attr in attrs {
240 match attr.name_or_empty() {
241 sym::rustc_allowed_through_unstable_modules => allowed_through_unstable_modules = true,
242 sym::unstable => {
243 if stab.is_some() {
244 handle_errors(&sess.parse_sess, attr.span, AttrError::MultipleStabilityLevels);
245 break;
246 }
247
248 if let Some((feature, level)) = parse_unstability(sess, attr) {
249 stab = Some((Stability { level, feature }, attr.span));
250 }
251 }
252 sym::stable => {
253 if stab.is_some() {
254 handle_errors(&sess.parse_sess, attr.span, AttrError::MultipleStabilityLevels);
255 break;
256 }
257 if let Some((feature, level)) = parse_stability(sess, attr) {
258 stab = Some((Stability { level, feature }, attr.span));
259 }
260 }
261 _ => {}
262 }
263 }
264
265 if allowed_through_unstable_modules {
266 match &mut stab {
267 Some((
268 Stability {
269 level: StabilityLevel::Stable { allowed_through_unstable_modules, .. },
270 ..
271 },
272 _,
273 )) => *allowed_through_unstable_modules = true,
274 _ => {
275 sess.emit_err(session_diagnostics::RustcAllowedUnstablePairing { span: item_sp });
276 }
277 }
278 }
279
280 stab
281 }
282
283 /// Collects stability info from `rustc_const_stable`/`rustc_const_unstable`/`rustc_promotable`
284 /// attributes in `attrs`. Returns `None` if no stability attributes are found.
find_const_stability( sess: &Session, attrs: &[Attribute], item_sp: Span, ) -> Option<(ConstStability, Span)>285 pub fn find_const_stability(
286 sess: &Session,
287 attrs: &[Attribute],
288 item_sp: Span,
289 ) -> Option<(ConstStability, Span)> {
290 let mut const_stab: Option<(ConstStability, Span)> = None;
291 let mut promotable = false;
292
293 for attr in attrs {
294 match attr.name_or_empty() {
295 sym::rustc_promotable => promotable = true,
296 sym::rustc_const_unstable => {
297 if const_stab.is_some() {
298 handle_errors(&sess.parse_sess, attr.span, AttrError::MultipleStabilityLevels);
299 break;
300 }
301
302 if let Some((feature, level)) = parse_unstability(sess, attr) {
303 const_stab =
304 Some((ConstStability { level, feature, promotable: false }, attr.span));
305 }
306 }
307 sym::rustc_const_stable => {
308 if const_stab.is_some() {
309 handle_errors(&sess.parse_sess, attr.span, AttrError::MultipleStabilityLevels);
310 break;
311 }
312 if let Some((feature, level)) = parse_stability(sess, attr) {
313 const_stab =
314 Some((ConstStability { level, feature, promotable: false }, attr.span));
315 }
316 }
317 _ => {}
318 }
319 }
320
321 // Merge the const-unstable info into the stability info
322 if promotable {
323 match &mut const_stab {
324 Some((stab, _)) => stab.promotable = promotable,
325 _ => _ = sess.emit_err(session_diagnostics::RustcPromotablePairing { span: item_sp }),
326 }
327 }
328
329 const_stab
330 }
331
332 /// Collects stability info from `rustc_default_body_unstable` attributes in `attrs`.
333 /// Returns `None` if no stability attributes are found.
find_body_stability( sess: &Session, attrs: &[Attribute], ) -> Option<(DefaultBodyStability, Span)>334 pub fn find_body_stability(
335 sess: &Session,
336 attrs: &[Attribute],
337 ) -> Option<(DefaultBodyStability, Span)> {
338 let mut body_stab: Option<(DefaultBodyStability, Span)> = None;
339
340 for attr in attrs {
341 if attr.has_name(sym::rustc_default_body_unstable) {
342 if body_stab.is_some() {
343 handle_errors(&sess.parse_sess, attr.span, AttrError::MultipleStabilityLevels);
344 break;
345 }
346
347 if let Some((feature, level)) = parse_unstability(sess, attr) {
348 body_stab = Some((DefaultBodyStability { level, feature }, attr.span));
349 }
350 }
351 }
352
353 body_stab
354 }
355
356 /// Read the content of a `stable`/`rustc_const_stable` attribute, and return the feature name and
357 /// its stability information.
parse_stability(sess: &Session, attr: &Attribute) -> Option<(Symbol, StabilityLevel)>358 fn parse_stability(sess: &Session, attr: &Attribute) -> Option<(Symbol, StabilityLevel)> {
359 let meta = attr.meta()?;
360 let MetaItem { kind: MetaItemKind::List(ref metas), .. } = meta else { return None };
361 let insert_or_error = |meta: &MetaItem, item: &mut Option<Symbol>| {
362 if item.is_some() {
363 handle_errors(
364 &sess.parse_sess,
365 meta.span,
366 AttrError::MultipleItem(pprust::path_to_string(&meta.path)),
367 );
368 return false;
369 }
370 if let Some(v) = meta.value_str() {
371 *item = Some(v);
372 true
373 } else {
374 sess.emit_err(session_diagnostics::IncorrectMetaItem { span: meta.span });
375 false
376 }
377 };
378
379 let mut feature = None;
380 let mut since = None;
381 for meta in metas {
382 let Some(mi) = meta.meta_item() else {
383 handle_errors(
384 &sess.parse_sess,
385 meta.span(),
386 AttrError::UnsupportedLiteral(UnsupportedLiteralReason::Generic, false),
387 );
388 return None;
389 };
390
391 match mi.name_or_empty() {
392 sym::feature => {
393 if !insert_or_error(mi, &mut feature) {
394 return None;
395 }
396 }
397 sym::since => {
398 if !insert_or_error(mi, &mut since) {
399 return None;
400 }
401 }
402 _ => {
403 handle_errors(
404 &sess.parse_sess,
405 meta.span(),
406 AttrError::UnknownMetaItem(
407 pprust::path_to_string(&mi.path),
408 &["feature", "since"],
409 ),
410 );
411 return None;
412 }
413 }
414 }
415
416 if let Some(s) = since && s.as_str() == VERSION_PLACEHOLDER {
417 since = Some(rust_version_symbol());
418 }
419
420 match (feature, since) {
421 (Some(feature), Some(since)) => {
422 let level = StabilityLevel::Stable { since, allowed_through_unstable_modules: false };
423 Some((feature, level))
424 }
425 (None, _) => {
426 handle_errors(&sess.parse_sess, attr.span, AttrError::MissingFeature);
427 None
428 }
429 _ => {
430 handle_errors(&sess.parse_sess, attr.span, AttrError::MissingSince);
431 None
432 }
433 }
434 }
435
436 /// Read the content of a `unstable`/`rustc_const_unstable`/`rustc_default_body_unstable`
437 /// attribute, and return the feature name and its stability information.
parse_unstability(sess: &Session, attr: &Attribute) -> Option<(Symbol, StabilityLevel)>438 fn parse_unstability(sess: &Session, attr: &Attribute) -> Option<(Symbol, StabilityLevel)> {
439 let meta = attr.meta()?;
440 let MetaItem { kind: MetaItemKind::List(ref metas), .. } = meta else { return None };
441 let insert_or_error = |meta: &MetaItem, item: &mut Option<Symbol>| {
442 if item.is_some() {
443 handle_errors(
444 &sess.parse_sess,
445 meta.span,
446 AttrError::MultipleItem(pprust::path_to_string(&meta.path)),
447 );
448 return false;
449 }
450 if let Some(v) = meta.value_str() {
451 *item = Some(v);
452 true
453 } else {
454 sess.emit_err(session_diagnostics::IncorrectMetaItem { span: meta.span });
455 false
456 }
457 };
458
459 let mut feature = None;
460 let mut reason = None;
461 let mut issue = None;
462 let mut issue_num = None;
463 let mut is_soft = false;
464 let mut implied_by = None;
465 for meta in metas {
466 let Some(mi) = meta.meta_item() else {
467 handle_errors(
468 &sess.parse_sess,
469 meta.span(),
470 AttrError::UnsupportedLiteral(UnsupportedLiteralReason::Generic, false),
471 );
472 return None;
473 };
474
475 match mi.name_or_empty() {
476 sym::feature => {
477 if !insert_or_error(mi, &mut feature) {
478 return None;
479 }
480 }
481 sym::reason => {
482 if !insert_or_error(mi, &mut reason) {
483 return None;
484 }
485 }
486 sym::issue => {
487 if !insert_or_error(mi, &mut issue) {
488 return None;
489 }
490
491 // These unwraps are safe because `insert_or_error` ensures the meta item
492 // is a name/value pair string literal.
493 issue_num = match issue.unwrap().as_str() {
494 "none" => None,
495 issue => match issue.parse::<NonZeroU32>() {
496 Ok(num) => Some(num),
497 Err(err) => {
498 sess.emit_err(
499 session_diagnostics::InvalidIssueString {
500 span: mi.span,
501 cause: session_diagnostics::InvalidIssueStringCause::from_int_error_kind(
502 mi.name_value_literal_span().unwrap(),
503 err.kind(),
504 ),
505 },
506 );
507 return None;
508 }
509 },
510 };
511 }
512 sym::soft => {
513 if !mi.is_word() {
514 sess.emit_err(session_diagnostics::SoftNoArgs { span: mi.span });
515 }
516 is_soft = true;
517 }
518 sym::implied_by => {
519 if !insert_or_error(mi, &mut implied_by) {
520 return None;
521 }
522 }
523 _ => {
524 handle_errors(
525 &sess.parse_sess,
526 meta.span(),
527 AttrError::UnknownMetaItem(
528 pprust::path_to_string(&mi.path),
529 &["feature", "reason", "issue", "soft", "implied_by"],
530 ),
531 );
532 return None;
533 }
534 }
535 }
536
537 match (feature, reason, issue) {
538 (Some(feature), reason, Some(_)) => {
539 if !rustc_lexer::is_ident(feature.as_str()) {
540 handle_errors(&sess.parse_sess, attr.span, AttrError::NonIdentFeature);
541 return None;
542 }
543 let level = StabilityLevel::Unstable {
544 reason: UnstableReason::from_opt_reason(reason),
545 issue: issue_num,
546 is_soft,
547 implied_by,
548 };
549 Some((feature, level))
550 }
551 (None, _, _) => {
552 handle_errors(&sess.parse_sess, attr.span, AttrError::MissingFeature);
553 return None;
554 }
555 _ => {
556 sess.emit_err(session_diagnostics::MissingIssue { span: attr.span });
557 return None;
558 }
559 }
560 }
561
find_crate_name(attrs: &[Attribute]) -> Option<Symbol>562 pub fn find_crate_name(attrs: &[Attribute]) -> Option<Symbol> {
563 attr::first_attr_value_str_by_name(attrs, sym::crate_name)
564 }
565
566 #[derive(Clone, Debug)]
567 pub struct Condition {
568 pub name: Symbol,
569 pub name_span: Span,
570 pub value: Option<Symbol>,
571 pub value_span: Option<Span>,
572 pub span: Span,
573 }
574
575 /// Tests if a cfg-pattern matches the cfg set
cfg_matches( cfg: &ast::MetaItem, sess: &ParseSess, lint_node_id: NodeId, features: Option<&Features>, ) -> bool576 pub fn cfg_matches(
577 cfg: &ast::MetaItem,
578 sess: &ParseSess,
579 lint_node_id: NodeId,
580 features: Option<&Features>,
581 ) -> bool {
582 eval_condition(cfg, sess, features, &mut |cfg| {
583 try_gate_cfg(cfg.name, cfg.span, sess, features);
584 match sess.check_config.expecteds.get(&cfg.name) {
585 Some(ExpectedValues::Some(values)) if !values.contains(&cfg.value) => {
586 sess.buffer_lint_with_diagnostic(
587 UNEXPECTED_CFGS,
588 cfg.span,
589 lint_node_id,
590 "unexpected `cfg` condition value",
591 BuiltinLintDiagnostics::UnexpectedCfgValue(
592 (cfg.name, cfg.name_span),
593 cfg.value.map(|v| (v, cfg.value_span.unwrap())),
594 ),
595 );
596 }
597 None if sess.check_config.exhaustive_names => {
598 sess.buffer_lint_with_diagnostic(
599 UNEXPECTED_CFGS,
600 cfg.span,
601 lint_node_id,
602 "unexpected `cfg` condition name",
603 BuiltinLintDiagnostics::UnexpectedCfgName(
604 (cfg.name, cfg.name_span),
605 cfg.value.map(|v| (v, cfg.value_span.unwrap())),
606 ),
607 );
608 }
609 _ => { /* not unexpected */ }
610 }
611 sess.config.contains(&(cfg.name, cfg.value))
612 })
613 }
614
try_gate_cfg(name: Symbol, span: Span, sess: &ParseSess, features: Option<&Features>)615 fn try_gate_cfg(name: Symbol, span: Span, sess: &ParseSess, features: Option<&Features>) {
616 let gate = find_gated_cfg(|sym| sym == name);
617 if let (Some(feats), Some(gated_cfg)) = (features, gate) {
618 gate_cfg(&gated_cfg, span, sess, feats);
619 }
620 }
621
gate_cfg(gated_cfg: &GatedCfg, cfg_span: Span, sess: &ParseSess, features: &Features)622 fn gate_cfg(gated_cfg: &GatedCfg, cfg_span: Span, sess: &ParseSess, features: &Features) {
623 let (cfg, feature, has_feature) = gated_cfg;
624 if !has_feature(features) && !cfg_span.allows_unstable(*feature) {
625 let explain = format!("`cfg({cfg})` is experimental and subject to change");
626 feature_err(sess, *feature, cfg_span, explain).emit();
627 }
628 }
629
630 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
631 struct Version {
632 major: u16,
633 minor: u16,
634 patch: u16,
635 }
636
parse_version(s: &str, allow_appendix: bool) -> Option<Version>637 fn parse_version(s: &str, allow_appendix: bool) -> Option<Version> {
638 let mut components = s.split('-');
639 let d = components.next()?;
640 if !allow_appendix && components.next().is_some() {
641 return None;
642 }
643 let mut digits = d.splitn(3, '.');
644 let major = digits.next()?.parse().ok()?;
645 let minor = digits.next()?.parse().ok()?;
646 let patch = digits.next().unwrap_or("0").parse().ok()?;
647 Some(Version { major, minor, patch })
648 }
649
650 /// Evaluate a cfg-like condition (with `any` and `all`), using `eval` to
651 /// evaluate individual items.
eval_condition( cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Features>, eval: &mut impl FnMut(Condition) -> bool, ) -> bool652 pub fn eval_condition(
653 cfg: &ast::MetaItem,
654 sess: &ParseSess,
655 features: Option<&Features>,
656 eval: &mut impl FnMut(Condition) -> bool,
657 ) -> bool {
658 match &cfg.kind {
659 ast::MetaItemKind::List(mis) if cfg.name_or_empty() == sym::version => {
660 try_gate_cfg(sym::version, cfg.span, sess, features);
661 let (min_version, span) = match &mis[..] {
662 [NestedMetaItem::Lit(MetaItemLit { kind: LitKind::Str(sym, ..), span, .. })] => {
663 (sym, span)
664 }
665 [
666 NestedMetaItem::Lit(MetaItemLit { span, .. })
667 | NestedMetaItem::MetaItem(MetaItem { span, .. }),
668 ] => {
669 sess.emit_err(session_diagnostics::ExpectedVersionLiteral { span: *span });
670 return false;
671 }
672 [..] => {
673 sess.emit_err(session_diagnostics::ExpectedSingleVersionLiteral {
674 span: cfg.span,
675 });
676 return false;
677 }
678 };
679 let Some(min_version) = parse_version(min_version.as_str(), false) else {
680 sess.emit_warning(session_diagnostics::UnknownVersionLiteral { span: *span });
681 return false;
682 };
683 let rustc_version = parse_version(env!("CFG_RELEASE"), true).unwrap();
684
685 // See https://github.com/rust-lang/rust/issues/64796#issuecomment-640851454 for details
686 if sess.assume_incomplete_release {
687 rustc_version > min_version
688 } else {
689 rustc_version >= min_version
690 }
691 }
692 ast::MetaItemKind::List(mis) => {
693 for mi in mis.iter() {
694 if !mi.is_meta_item() {
695 handle_errors(
696 sess,
697 mi.span(),
698 AttrError::UnsupportedLiteral(UnsupportedLiteralReason::Generic, false),
699 );
700 return false;
701 }
702 }
703
704 // The unwraps below may look dangerous, but we've already asserted
705 // that they won't fail with the loop above.
706 match cfg.name_or_empty() {
707 sym::any => mis
708 .iter()
709 // We don't use any() here, because we want to evaluate all cfg condition
710 // as eval_condition can (and does) extra checks
711 .fold(false, |res, mi| {
712 res | eval_condition(mi.meta_item().unwrap(), sess, features, eval)
713 }),
714 sym::all => mis
715 .iter()
716 // We don't use all() here, because we want to evaluate all cfg condition
717 // as eval_condition can (and does) extra checks
718 .fold(true, |res, mi| {
719 res & eval_condition(mi.meta_item().unwrap(), sess, features, eval)
720 }),
721 sym::not => {
722 if mis.len() != 1 {
723 sess.emit_err(session_diagnostics::ExpectedOneCfgPattern {
724 span: cfg.span,
725 });
726 return false;
727 }
728
729 !eval_condition(mis[0].meta_item().unwrap(), sess, features, eval)
730 }
731 sym::target => {
732 if let Some(features) = features && !features.cfg_target_compact {
733 feature_err(
734 sess,
735 sym::cfg_target_compact,
736 cfg.span,
737 "compact `cfg(target(..))` is experimental and subject to change"
738 ).emit();
739 }
740
741 mis.iter().fold(true, |res, mi| {
742 let mut mi = mi.meta_item().unwrap().clone();
743 if let [seg, ..] = &mut mi.path.segments[..] {
744 seg.ident.name = Symbol::intern(&format!("target_{}", seg.ident.name));
745 }
746
747 res & eval_condition(&mi, sess, features, eval)
748 })
749 }
750 _ => {
751 sess.emit_err(session_diagnostics::InvalidPredicate {
752 span: cfg.span,
753 predicate: pprust::path_to_string(&cfg.path),
754 });
755 false
756 }
757 }
758 }
759 ast::MetaItemKind::Word | MetaItemKind::NameValue(..) if cfg.path.segments.len() != 1 => {
760 sess.emit_err(session_diagnostics::CfgPredicateIdentifier { span: cfg.path.span });
761 true
762 }
763 MetaItemKind::NameValue(lit) if !lit.kind.is_str() => {
764 handle_errors(
765 sess,
766 lit.span,
767 AttrError::UnsupportedLiteral(
768 UnsupportedLiteralReason::CfgString,
769 lit.kind.is_bytestr(),
770 ),
771 );
772 true
773 }
774 ast::MetaItemKind::Word | ast::MetaItemKind::NameValue(..) => {
775 let ident = cfg.ident().expect("multi-segment cfg predicate");
776 eval(Condition {
777 name: ident.name,
778 name_span: ident.span,
779 value: cfg.value_str(),
780 value_span: cfg.name_value_literal_span(),
781 span: cfg.span,
782 })
783 }
784 }
785 }
786
787 #[derive(Copy, Debug, Encodable, Decodable, Clone, HashStable_Generic)]
788 pub struct Deprecation {
789 pub since: Option<Symbol>,
790 /// The note to issue a reason.
791 pub note: Option<Symbol>,
792 /// A text snippet used to completely replace any use of the deprecated item in an expression.
793 ///
794 /// This is currently unstable.
795 pub suggestion: Option<Symbol>,
796
797 /// Whether to treat the since attribute as being a Rust version identifier
798 /// (rather than an opaque string).
799 pub is_since_rustc_version: bool,
800 }
801
802 /// Finds the deprecation attribute. `None` if none exists.
find_deprecation(sess: &Session, attrs: &[Attribute]) -> Option<(Deprecation, Span)>803 pub fn find_deprecation(sess: &Session, attrs: &[Attribute]) -> Option<(Deprecation, Span)> {
804 find_deprecation_generic(sess, attrs.iter())
805 }
806
find_deprecation_generic<'a, I>(sess: &Session, attrs_iter: I) -> Option<(Deprecation, Span)> where I: Iterator<Item = &'a Attribute>,807 fn find_deprecation_generic<'a, I>(sess: &Session, attrs_iter: I) -> Option<(Deprecation, Span)>
808 where
809 I: Iterator<Item = &'a Attribute>,
810 {
811 let mut depr: Option<(Deprecation, Span)> = None;
812 let is_rustc = sess.features_untracked().staged_api;
813
814 'outer: for attr in attrs_iter {
815 if !attr.has_name(sym::deprecated) {
816 continue;
817 }
818
819 let Some(meta) = attr.meta() else {
820 continue;
821 };
822 let mut since = None;
823 let mut note = None;
824 let mut suggestion = None;
825 match &meta.kind {
826 MetaItemKind::Word => {}
827 MetaItemKind::NameValue(..) => note = meta.value_str(),
828 MetaItemKind::List(list) => {
829 let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
830 if item.is_some() {
831 handle_errors(
832 &sess.parse_sess,
833 meta.span,
834 AttrError::MultipleItem(pprust::path_to_string(&meta.path)),
835 );
836 return false;
837 }
838 if let Some(v) = meta.value_str() {
839 *item = Some(v);
840 true
841 } else {
842 if let Some(lit) = meta.name_value_literal() {
843 handle_errors(
844 &sess.parse_sess,
845 lit.span,
846 AttrError::UnsupportedLiteral(
847 UnsupportedLiteralReason::DeprecatedString,
848 lit.kind.is_bytestr(),
849 ),
850 );
851 } else {
852 sess.emit_err(session_diagnostics::IncorrectMetaItem2 {
853 span: meta.span,
854 });
855 }
856
857 false
858 }
859 };
860
861 for meta in list {
862 match meta {
863 NestedMetaItem::MetaItem(mi) => match mi.name_or_empty() {
864 sym::since => {
865 if !get(mi, &mut since) {
866 continue 'outer;
867 }
868 }
869 sym::note => {
870 if !get(mi, &mut note) {
871 continue 'outer;
872 }
873 }
874 sym::suggestion => {
875 if !sess.features_untracked().deprecated_suggestion {
876 sess.emit_err(session_diagnostics::DeprecatedItemSuggestion {
877 span: mi.span,
878 is_nightly: sess.is_nightly_build().then_some(()),
879 details: (),
880 });
881 }
882
883 if !get(mi, &mut suggestion) {
884 continue 'outer;
885 }
886 }
887 _ => {
888 handle_errors(
889 &sess.parse_sess,
890 meta.span(),
891 AttrError::UnknownMetaItem(
892 pprust::path_to_string(&mi.path),
893 if sess.features_untracked().deprecated_suggestion {
894 &["since", "note", "suggestion"]
895 } else {
896 &["since", "note"]
897 },
898 ),
899 );
900 continue 'outer;
901 }
902 },
903 NestedMetaItem::Lit(lit) => {
904 handle_errors(
905 &sess.parse_sess,
906 lit.span,
907 AttrError::UnsupportedLiteral(
908 UnsupportedLiteralReason::DeprecatedKvPair,
909 false,
910 ),
911 );
912 continue 'outer;
913 }
914 }
915 }
916 }
917 }
918
919 if is_rustc {
920 if since.is_none() {
921 handle_errors(&sess.parse_sess, attr.span, AttrError::MissingSince);
922 continue;
923 }
924
925 if note.is_none() {
926 sess.emit_err(session_diagnostics::MissingNote { span: attr.span });
927 continue;
928 }
929 }
930
931 depr = Some((
932 Deprecation { since, note, suggestion, is_since_rustc_version: is_rustc },
933 attr.span,
934 ));
935 }
936
937 depr
938 }
939
940 #[derive(PartialEq, Debug, Encodable, Decodable, Copy, Clone)]
941 pub enum ReprAttr {
942 ReprInt(IntType),
943 ReprC,
944 ReprPacked(u32),
945 ReprSimd,
946 ReprTransparent,
947 ReprAlign(u32),
948 }
949
950 #[derive(Eq, PartialEq, Debug, Copy, Clone)]
951 #[derive(Encodable, Decodable, HashStable_Generic)]
952 pub enum IntType {
953 SignedInt(ast::IntTy),
954 UnsignedInt(ast::UintTy),
955 }
956
957 impl IntType {
958 #[inline]
is_signed(self) -> bool959 pub fn is_signed(self) -> bool {
960 use IntType::*;
961
962 match self {
963 SignedInt(..) => true,
964 UnsignedInt(..) => false,
965 }
966 }
967 }
968
969 /// Parse #[repr(...)] forms.
970 ///
971 /// Valid repr contents: any of the primitive integral type names (see
972 /// `int_type_of_word`, below) to specify enum discriminant type; `C`, to use
973 /// the same discriminant size that the corresponding C enum would or C
974 /// structure layout, `packed` to remove padding, and `transparent` to delegate representation
975 /// concerns to the only non-ZST field.
find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr>976 pub fn find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
977 if attr.has_name(sym::repr) { parse_repr_attr(sess, attr) } else { Vec::new() }
978 }
979
parse_repr_attr(sess: &Session, attr: &Attribute) -> Vec<ReprAttr>980 pub fn parse_repr_attr(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
981 assert!(attr.has_name(sym::repr), "expected `#[repr(..)]`, found: {attr:?}");
982 use ReprAttr::*;
983 let mut acc = Vec::new();
984 let diagnostic = &sess.parse_sess.span_diagnostic;
985
986 if let Some(items) = attr.meta_item_list() {
987 for item in items {
988 let mut recognised = false;
989 if item.is_word() {
990 let hint = match item.name_or_empty() {
991 sym::C => Some(ReprC),
992 sym::packed => Some(ReprPacked(1)),
993 sym::simd => Some(ReprSimd),
994 sym::transparent => Some(ReprTransparent),
995 sym::align => {
996 sess.emit_err(session_diagnostics::InvalidReprAlignNeedArg {
997 span: item.span(),
998 });
999 recognised = true;
1000 None
1001 }
1002 name => int_type_of_word(name).map(ReprInt),
1003 };
1004
1005 if let Some(h) = hint {
1006 recognised = true;
1007 acc.push(h);
1008 }
1009 } else if let Some((name, value)) = item.name_value_literal() {
1010 let mut literal_error = None;
1011 if name == sym::align {
1012 recognised = true;
1013 match parse_alignment(&value.kind) {
1014 Ok(literal) => acc.push(ReprAlign(literal)),
1015 Err(message) => literal_error = Some(message),
1016 };
1017 } else if name == sym::packed {
1018 recognised = true;
1019 match parse_alignment(&value.kind) {
1020 Ok(literal) => acc.push(ReprPacked(literal)),
1021 Err(message) => literal_error = Some(message),
1022 };
1023 } else if matches!(name, sym::C | sym::simd | sym::transparent)
1024 || int_type_of_word(name).is_some()
1025 {
1026 recognised = true;
1027 sess.emit_err(session_diagnostics::InvalidReprHintNoParen {
1028 span: item.span(),
1029 name: name.to_ident_string(),
1030 });
1031 }
1032 if let Some(literal_error) = literal_error {
1033 sess.emit_err(session_diagnostics::InvalidReprGeneric {
1034 span: item.span(),
1035 repr_arg: name.to_ident_string(),
1036 error_part: literal_error,
1037 });
1038 }
1039 } else if let Some(meta_item) = item.meta_item() {
1040 match &meta_item.kind {
1041 MetaItemKind::NameValue(value) => {
1042 if meta_item.has_name(sym::align) || meta_item.has_name(sym::packed) {
1043 let name = meta_item.name_or_empty().to_ident_string();
1044 recognised = true;
1045 sess.emit_err(session_diagnostics::IncorrectReprFormatGeneric {
1046 span: item.span(),
1047 repr_arg: &name,
1048 cause: IncorrectReprFormatGenericCause::from_lit_kind(
1049 item.span(),
1050 &value.kind,
1051 &name,
1052 ),
1053 });
1054 } else if matches!(
1055 meta_item.name_or_empty(),
1056 sym::C | sym::simd | sym::transparent
1057 ) || int_type_of_word(meta_item.name_or_empty()).is_some()
1058 {
1059 recognised = true;
1060 sess.emit_err(session_diagnostics::InvalidReprHintNoValue {
1061 span: meta_item.span,
1062 name: meta_item.name_or_empty().to_ident_string(),
1063 });
1064 }
1065 }
1066 MetaItemKind::List(_) => {
1067 if meta_item.has_name(sym::align) {
1068 recognised = true;
1069 sess.emit_err(session_diagnostics::IncorrectReprFormatAlignOneArg {
1070 span: meta_item.span,
1071 });
1072 } else if meta_item.has_name(sym::packed) {
1073 recognised = true;
1074 sess.emit_err(
1075 session_diagnostics::IncorrectReprFormatPackedOneOrZeroArg {
1076 span: meta_item.span,
1077 },
1078 );
1079 } else if matches!(
1080 meta_item.name_or_empty(),
1081 sym::C | sym::simd | sym::transparent
1082 ) || int_type_of_word(meta_item.name_or_empty()).is_some()
1083 {
1084 recognised = true;
1085 sess.emit_err(session_diagnostics::InvalidReprHintNoParen {
1086 span: meta_item.span,
1087 name: meta_item.name_or_empty().to_ident_string(),
1088 });
1089 }
1090 }
1091 _ => (),
1092 }
1093 }
1094 if !recognised {
1095 // Not a word we recognize. This will be caught and reported by
1096 // the `check_mod_attrs` pass, but this pass doesn't always run
1097 // (e.g. if we only pretty-print the source), so we have to gate
1098 // the `delay_span_bug` call as follows:
1099 if sess.opts.pretty.map_or(true, |pp| pp.needs_analysis()) {
1100 diagnostic.delay_span_bug(item.span(), "unrecognized representation hint");
1101 }
1102 }
1103 }
1104 }
1105 acc
1106 }
1107
int_type_of_word(s: Symbol) -> Option<IntType>1108 fn int_type_of_word(s: Symbol) -> Option<IntType> {
1109 use IntType::*;
1110
1111 match s {
1112 sym::i8 => Some(SignedInt(ast::IntTy::I8)),
1113 sym::u8 => Some(UnsignedInt(ast::UintTy::U8)),
1114 sym::i16 => Some(SignedInt(ast::IntTy::I16)),
1115 sym::u16 => Some(UnsignedInt(ast::UintTy::U16)),
1116 sym::i32 => Some(SignedInt(ast::IntTy::I32)),
1117 sym::u32 => Some(UnsignedInt(ast::UintTy::U32)),
1118 sym::i64 => Some(SignedInt(ast::IntTy::I64)),
1119 sym::u64 => Some(UnsignedInt(ast::UintTy::U64)),
1120 sym::i128 => Some(SignedInt(ast::IntTy::I128)),
1121 sym::u128 => Some(UnsignedInt(ast::UintTy::U128)),
1122 sym::isize => Some(SignedInt(ast::IntTy::Isize)),
1123 sym::usize => Some(UnsignedInt(ast::UintTy::Usize)),
1124 _ => None,
1125 }
1126 }
1127
1128 pub enum TransparencyError {
1129 UnknownTransparency(Symbol, Span),
1130 MultipleTransparencyAttrs(Span, Span),
1131 }
1132
find_transparency( attrs: &[Attribute], macro_rules: bool, ) -> (Transparency, Option<TransparencyError>)1133 pub fn find_transparency(
1134 attrs: &[Attribute],
1135 macro_rules: bool,
1136 ) -> (Transparency, Option<TransparencyError>) {
1137 let mut transparency = None;
1138 let mut error = None;
1139 for attr in attrs {
1140 if attr.has_name(sym::rustc_macro_transparency) {
1141 if let Some((_, old_span)) = transparency {
1142 error = Some(TransparencyError::MultipleTransparencyAttrs(old_span, attr.span));
1143 break;
1144 } else if let Some(value) = attr.value_str() {
1145 transparency = Some((
1146 match value {
1147 sym::transparent => Transparency::Transparent,
1148 sym::semitransparent => Transparency::SemiTransparent,
1149 sym::opaque => Transparency::Opaque,
1150 _ => {
1151 error = Some(TransparencyError::UnknownTransparency(value, attr.span));
1152 continue;
1153 }
1154 },
1155 attr.span,
1156 ));
1157 }
1158 }
1159 }
1160 let fallback = if macro_rules { Transparency::SemiTransparent } else { Transparency::Opaque };
1161 (transparency.map_or(fallback, |t| t.0), error)
1162 }
1163
allow_internal_unstable<'a>( sess: &'a Session, attrs: &'a [Attribute], ) -> impl Iterator<Item = Symbol> + 'a1164 pub fn allow_internal_unstable<'a>(
1165 sess: &'a Session,
1166 attrs: &'a [Attribute],
1167 ) -> impl Iterator<Item = Symbol> + 'a {
1168 allow_unstable(sess, attrs, sym::allow_internal_unstable)
1169 }
1170
rustc_allow_const_fn_unstable<'a>( sess: &'a Session, attrs: &'a [Attribute], ) -> impl Iterator<Item = Symbol> + 'a1171 pub fn rustc_allow_const_fn_unstable<'a>(
1172 sess: &'a Session,
1173 attrs: &'a [Attribute],
1174 ) -> impl Iterator<Item = Symbol> + 'a {
1175 allow_unstable(sess, attrs, sym::rustc_allow_const_fn_unstable)
1176 }
1177
allow_unstable<'a>( sess: &'a Session, attrs: &'a [Attribute], symbol: Symbol, ) -> impl Iterator<Item = Symbol> + 'a1178 fn allow_unstable<'a>(
1179 sess: &'a Session,
1180 attrs: &'a [Attribute],
1181 symbol: Symbol,
1182 ) -> impl Iterator<Item = Symbol> + 'a {
1183 let attrs = attr::filter_by_name(attrs, symbol);
1184 let list = attrs
1185 .filter_map(move |attr| {
1186 attr.meta_item_list().or_else(|| {
1187 sess.emit_err(session_diagnostics::ExpectsFeatureList {
1188 span: attr.span,
1189 name: symbol.to_ident_string(),
1190 });
1191 None
1192 })
1193 })
1194 .flatten();
1195
1196 list.into_iter().filter_map(move |it| {
1197 let name = it.ident().map(|ident| ident.name);
1198 if name.is_none() {
1199 sess.emit_err(session_diagnostics::ExpectsFeatures {
1200 span: it.span(),
1201 name: symbol.to_ident_string(),
1202 });
1203 }
1204 name
1205 })
1206 }
1207
parse_alignment(node: &ast::LitKind) -> Result<u32, &'static str>1208 pub fn parse_alignment(node: &ast::LitKind) -> Result<u32, &'static str> {
1209 if let ast::LitKind::Int(literal, ast::LitIntType::Unsuffixed) = node {
1210 if literal.is_power_of_two() {
1211 // rustc_middle::ty::layout::Align restricts align to <= 2^29
1212 if *literal <= 1 << 29 { Ok(*literal as u32) } else { Err("larger than 2^29") }
1213 } else {
1214 Err("not a power of two")
1215 }
1216 } else {
1217 Err("not an unsuffixed integer")
1218 }
1219 }
1220