rustc_feature/
builtin_attrs.rs

1//! Built-in attributes and `cfg` flag gating.
2
3use std::sync::LazyLock;
4
5use AttributeDuplicates::*;
6use AttributeGate::*;
7use AttributeType::*;
8use rustc_data_structures::fx::FxHashMap;
9use rustc_hir::attrs::EncodeCrossCrate;
10use rustc_span::edition::Edition;
11use rustc_span::{Symbol, sym};
12
13use crate::Features;
14
15type GateFn = fn(&Features) -> bool;
16
17pub type GatedCfg = (Symbol, Symbol, GateFn);
18
19/// `cfg(...)`'s that are feature gated.
20const GATED_CFGS: &[GatedCfg] = &[
21    // (name in cfg, feature, function to check if the feature is enabled)
22    (sym::overflow_checks, sym::cfg_overflow_checks, Features::cfg_overflow_checks),
23    (sym::ub_checks, sym::cfg_ub_checks, Features::cfg_ub_checks),
24    (sym::contract_checks, sym::cfg_contract_checks, Features::cfg_contract_checks),
25    (sym::target_thread_local, sym::cfg_target_thread_local, Features::cfg_target_thread_local),
26    (
27        sym::target_has_atomic_equal_alignment,
28        sym::cfg_target_has_atomic_equal_alignment,
29        Features::cfg_target_has_atomic_equal_alignment,
30    ),
31    (
32        sym::target_has_atomic_load_store,
33        sym::cfg_target_has_atomic,
34        Features::cfg_target_has_atomic,
35    ),
36    (sym::sanitize, sym::cfg_sanitize, Features::cfg_sanitize),
37    (sym::version, sym::cfg_version, Features::cfg_version),
38    (sym::relocation_model, sym::cfg_relocation_model, Features::cfg_relocation_model),
39    (sym::sanitizer_cfi_generalize_pointers, sym::cfg_sanitizer_cfi, Features::cfg_sanitizer_cfi),
40    (sym::sanitizer_cfi_normalize_integers, sym::cfg_sanitizer_cfi, Features::cfg_sanitizer_cfi),
41    // this is consistent with naming of the compiler flag it's for
42    (sym::fmt_debug, sym::fmt_debug, Features::fmt_debug),
43    (sym::emscripten_wasm_eh, sym::cfg_emscripten_wasm_eh, Features::cfg_emscripten_wasm_eh),
44    (
45        sym::target_has_reliable_f16,
46        sym::cfg_target_has_reliable_f16_f128,
47        Features::cfg_target_has_reliable_f16_f128,
48    ),
49    (
50        sym::target_has_reliable_f16_math,
51        sym::cfg_target_has_reliable_f16_f128,
52        Features::cfg_target_has_reliable_f16_f128,
53    ),
54    (
55        sym::target_has_reliable_f128,
56        sym::cfg_target_has_reliable_f16_f128,
57        Features::cfg_target_has_reliable_f16_f128,
58    ),
59    (
60        sym::target_has_reliable_f128_math,
61        sym::cfg_target_has_reliable_f16_f128,
62        Features::cfg_target_has_reliable_f16_f128,
63    ),
64];
65
66/// Find a gated cfg determined by the `pred`icate which is given the cfg's name.
67pub fn find_gated_cfg(pred: impl Fn(Symbol) -> bool) -> Option<&'static GatedCfg> {
68    GATED_CFGS.iter().find(|(cfg_sym, ..)| pred(*cfg_sym))
69}
70
71// If you change this, please modify `src/doc/unstable-book` as well. You must
72// move that documentation into the relevant place in the other docs, and
73// remove the chapter on the flag.
74
75#[derive(Copy, Clone, PartialEq, Debug)]
76pub enum AttributeType {
77    /// Normal, builtin attribute that is consumed
78    /// by the compiler before the unused_attribute check
79    Normal,
80
81    /// Builtin attribute that is only allowed at the crate level
82    CrateLevel,
83}
84
85#[derive(Copy, Clone, PartialEq, Debug)]
86pub enum AttributeSafety {
87    /// Normal attribute that does not need `#[unsafe(...)]`
88    Normal,
89
90    /// Unsafe attribute that requires safety obligations to be discharged.
91    ///
92    /// An error is emitted when `#[unsafe(...)]` is omitted, except when the attribute's edition
93    /// is less than the one stored in `unsafe_since`. This handles attributes that were safe in
94    /// earlier editions, but become unsafe in later ones.
95    Unsafe { unsafe_since: Option<Edition> },
96}
97
98#[derive(Clone, Debug, Copy)]
99pub enum AttributeGate {
100    /// A gated attribute which requires a feature gate to be enabled.
101    Gated {
102        /// The feature gate, for example `#![feature(rustc_attrs)]` for rustc_* attributes.
103        feature: Symbol,
104        /// The error message displayed when an attempt is made to use the attribute without its feature gate.
105        message: &'static str,
106        /// Check function to be called during the `PostExpansionVisitor` pass.
107        check: fn(&Features) -> bool,
108        /// Notes to be displayed when an attempt is made to use the attribute without its feature gate.
109        notes: &'static [&'static str],
110    },
111    /// Ungated attribute, can be used on all release channels
112    Ungated,
113}
114
115// FIXME(jdonszelmann): move to rustc_hir::attrs
116/// A template that the attribute input must match.
117/// Only top-level shape (`#[attr]` vs `#[attr(...)]` vs `#[attr = ...]`) is considered now.
118#[derive(Clone, Copy, Default)]
119pub struct AttributeTemplate {
120    /// If `true`, the attribute is allowed to be a bare word like `#[test]`.
121    pub word: bool,
122    /// If `Some`, the attribute is allowed to take a list of items like `#[allow(..)]`.
123    pub list: Option<&'static str>,
124    /// If non-empty, the attribute is allowed to take a list containing exactly
125    /// one of the listed words, like `#[coverage(off)]`.
126    pub one_of: &'static [Symbol],
127    /// If `Some`, the attribute is allowed to be a name/value pair where the
128    /// value is a string, like `#[must_use = "reason"]`.
129    pub name_value_str: Option<&'static str>,
130}
131
132impl AttributeTemplate {
133    pub fn suggestions(&self, inner: bool, name: impl std::fmt::Display) -> Vec<String> {
134        let mut suggestions = vec![];
135        let inner = if inner { "!" } else { "" };
136        if self.word {
137            suggestions.push(format!("#{inner}[{name}]"));
138        }
139        if let Some(descr) = self.list {
140            suggestions.push(format!("#{inner}[{name}({descr})]"));
141        }
142        suggestions.extend(self.one_of.iter().map(|&word| format!("#{inner}[{name}({word})]")));
143        if let Some(descr) = self.name_value_str {
144            suggestions.push(format!("#{inner}[{name} = \"{descr}\"]"));
145        }
146        suggestions.sort();
147
148        suggestions
149    }
150}
151
152/// How to handle multiple duplicate attributes on the same item.
153#[derive(Clone, Copy, Default)]
154pub enum AttributeDuplicates {
155    /// Duplicates of this attribute are allowed.
156    ///
157    /// This should only be used with attributes where duplicates have semantic
158    /// meaning, or some kind of "additive" behavior. For example, `#[warn(..)]`
159    /// can be specified multiple times, and it combines all the entries. Or use
160    /// this if there is validation done elsewhere.
161    #[default]
162    DuplicatesOk,
163    /// Duplicates after the first attribute will be an unused_attribute warning.
164    ///
165    /// This is usually used for "word" attributes, where they are used as a
166    /// boolean marker, like `#[used]`. It is not necessarily wrong that there
167    /// are duplicates, but the others should probably be removed.
168    WarnFollowing,
169    /// Same as `WarnFollowing`, but only issues warnings for word-style attributes.
170    ///
171    /// This is only for special cases, for example multiple `#[macro_use]` can
172    /// be warned, but multiple `#[macro_use(...)]` should not because the list
173    /// form has different meaning from the word form.
174    WarnFollowingWordOnly,
175    /// Duplicates after the first attribute will be an error.
176    ///
177    /// This should be used where duplicates would be ignored, but carry extra
178    /// meaning that could cause confusion. For example, `#[stable(since="1.0")]
179    /// #[stable(since="2.0")]`, which version should be used for `stable`?
180    ErrorFollowing,
181    /// Duplicates preceding the last instance of the attribute will be an error.
182    ///
183    /// This is the same as `ErrorFollowing`, except the last attribute is the
184    /// one that is "used". This is typically used in cases like codegen
185    /// attributes which usually only honor the last attribute.
186    ErrorPreceding,
187    /// Duplicates after the first attribute will be an unused_attribute warning
188    /// with a note that this will be an error in the future.
189    ///
190    /// This should be used for attributes that should be `ErrorFollowing`, but
191    /// because older versions of rustc silently accepted (and ignored) the
192    /// attributes, this is used to transition.
193    FutureWarnFollowing,
194    /// Duplicates preceding the last instance of the attribute will be a
195    /// warning, with a note that this will be an error in the future.
196    ///
197    /// This is the same as `FutureWarnFollowing`, except the last attribute is
198    /// the one that is "used". Ideally these can eventually migrate to
199    /// `ErrorPreceding`.
200    FutureWarnPreceding,
201}
202
203/// A convenience macro for constructing attribute templates.
204/// E.g., `template!(Word, List: "description")` means that the attribute
205/// supports forms `#[attr]` and `#[attr(description)]`.
206#[macro_export]
207macro_rules! template {
208    (Word) => { $crate::template!(@ true, None, &[], None) };
209    (List: $descr: expr) => { $crate::template!(@ false, Some($descr), &[], None) };
210    (OneOf: $one_of: expr) => { $crate::template!(@ false, None, $one_of, None) };
211    (NameValueStr: $descr: expr) => { $crate::template!(@ false, None, &[], Some($descr)) };
212    (Word, List: $descr: expr) => { $crate::template!(@ true, Some($descr), &[], None) };
213    (Word, NameValueStr: $descr: expr) => { $crate::template!(@ true, None, &[], Some($descr)) };
214    (List: $descr1: expr, NameValueStr: $descr2: expr) => {
215        $crate::template!(@ false, Some($descr1), &[], Some($descr2))
216    };
217    (Word, List: $descr1: expr, NameValueStr: $descr2: expr) => {
218        $crate::template!(@ true, Some($descr1), &[], Some($descr2))
219    };
220    (@ $word: expr, $list: expr, $one_of: expr, $name_value_str: expr) => { $crate::AttributeTemplate {
221        word: $word, list: $list, one_of: $one_of, name_value_str: $name_value_str
222    } };
223}
224
225macro_rules! ungated {
226    (unsafe($edition:ident) $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
227        BuiltinAttribute {
228            name: sym::$attr,
229            encode_cross_crate: $encode_cross_crate,
230            type_: $typ,
231            safety: AttributeSafety::Unsafe { unsafe_since: Some(Edition::$edition) },
232            template: $tpl,
233            gate: Ungated,
234            duplicates: $duplicates,
235        }
236    };
237    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
238        BuiltinAttribute {
239            name: sym::$attr,
240            encode_cross_crate: $encode_cross_crate,
241            type_: $typ,
242            safety: AttributeSafety::Unsafe { unsafe_since: None },
243            template: $tpl,
244            gate: Ungated,
245            duplicates: $duplicates,
246        }
247    };
248    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
249        BuiltinAttribute {
250            name: sym::$attr,
251            encode_cross_crate: $encode_cross_crate,
252            type_: $typ,
253            safety: AttributeSafety::Normal,
254            template: $tpl,
255            gate: Ungated,
256            duplicates: $duplicates,
257        }
258    };
259}
260
261macro_rules! gated {
262    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $gate:ident, $message:expr $(,)?) => {
263        BuiltinAttribute {
264            name: sym::$attr,
265            encode_cross_crate: $encode_cross_crate,
266            type_: $typ,
267            safety: AttributeSafety::Unsafe { unsafe_since: None },
268            template: $tpl,
269            duplicates: $duplicates,
270            gate: Gated {
271                feature: sym::$gate,
272                message: $message,
273                check: Features::$gate,
274                notes: &[],
275            },
276        }
277    };
278    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $message:expr $(,)?) => {
279        BuiltinAttribute {
280            name: sym::$attr,
281            encode_cross_crate: $encode_cross_crate,
282            type_: $typ,
283            safety: AttributeSafety::Unsafe { unsafe_since: None },
284            template: $tpl,
285            duplicates: $duplicates,
286            gate: Gated {
287                feature: sym::$attr,
288                message: $message,
289                check: Features::$attr,
290                notes: &[],
291            },
292        }
293    };
294    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $gate:ident, $message:expr $(,)?) => {
295        BuiltinAttribute {
296            name: sym::$attr,
297            encode_cross_crate: $encode_cross_crate,
298            type_: $typ,
299            safety: AttributeSafety::Normal,
300            template: $tpl,
301            duplicates: $duplicates,
302            gate: Gated {
303                feature: sym::$gate,
304                message: $message,
305                check: Features::$gate,
306                notes: &[],
307            },
308        }
309    };
310    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $message:expr $(,)?) => {
311        BuiltinAttribute {
312            name: sym::$attr,
313            encode_cross_crate: $encode_cross_crate,
314            type_: $typ,
315            safety: AttributeSafety::Normal,
316            template: $tpl,
317            duplicates: $duplicates,
318            gate: Gated {
319                feature: sym::$attr,
320                message: $message,
321                check: Features::$attr,
322                notes: &[],
323            },
324        }
325    };
326}
327
328macro_rules! rustc_attr {
329    (TEST, $attr:ident, $typ:expr, $tpl:expr, $duplicate:expr, $encode_cross_crate:expr $(,)?) => {
330        rustc_attr!(
331            $attr,
332            $typ,
333            $tpl,
334            $duplicate,
335            $encode_cross_crate,
336            concat!(
337                "the `#[",
338                stringify!($attr),
339                "]` attribute is used for rustc unit tests"
340            ),
341        )
342    };
343    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $($notes:expr),* $(,)?) => {
344        BuiltinAttribute {
345            name: sym::$attr,
346            encode_cross_crate: $encode_cross_crate,
347            type_: $typ,
348            safety: AttributeSafety::Normal,
349            template: $tpl,
350            duplicates: $duplicates,
351            gate: Gated {
352                feature: sym::rustc_attrs,
353                message: "use of an internal attribute",
354                check: Features::rustc_attrs,
355                notes: &[
356                    concat!("the `#[",
357                    stringify!($attr),
358                    "]` attribute is an internal implementation detail that will never be stable"),
359                    $($notes),*
360                    ]
361            },
362        }
363    };
364}
365
366macro_rules! experimental {
367    ($attr:ident) => {
368        concat!("the `#[", stringify!($attr), "]` attribute is an experimental feature")
369    };
370}
371
372pub struct BuiltinAttribute {
373    pub name: Symbol,
374    /// Whether this attribute is encode cross crate.
375    ///
376    /// If so, it is encoded in the crate metadata.
377    /// Otherwise, it can only be used in the local crate.
378    pub encode_cross_crate: EncodeCrossCrate,
379    pub type_: AttributeType,
380    pub safety: AttributeSafety,
381    pub template: AttributeTemplate,
382    pub duplicates: AttributeDuplicates,
383    pub gate: AttributeGate,
384}
385
386/// Attributes that have a special meaning to rustc or rustdoc.
387#[rustfmt::skip]
388pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
389    // ==========================================================================
390    // Stable attributes:
391    // ==========================================================================
392
393    // Conditional compilation:
394    ungated!(cfg, Normal, template!(List: "predicate"), DuplicatesOk, EncodeCrossCrate::Yes),
395    ungated!(cfg_attr, Normal, template!(List: "predicate, attr1, attr2, ..."), DuplicatesOk, EncodeCrossCrate::Yes),
396
397    // Testing:
398    ungated!(
399        ignore, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing,
400        EncodeCrossCrate::No,
401    ),
402    ungated!(
403        should_panic, Normal,
404        template!(Word, List: r#"expected = "reason""#, NameValueStr: "reason"), FutureWarnFollowing,
405        EncodeCrossCrate::No,
406    ),
407    // FIXME(Centril): This can be used on stable but shouldn't.
408    ungated!(
409        reexport_test_harness_main, CrateLevel, template!(NameValueStr: "name"), ErrorFollowing,
410        EncodeCrossCrate::No,
411    ),
412
413    // Macros:
414    ungated!(automatically_derived, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes),
415    ungated!(
416        macro_use, Normal, template!(Word, List: "name1, name2, ..."), WarnFollowingWordOnly,
417        EncodeCrossCrate::No,
418    ),
419    ungated!(macro_escape, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No), // Deprecated synonym for `macro_use`.
420    ungated!(
421        macro_export, Normal, template!(Word, List: "local_inner_macros"),
422        WarnFollowing, EncodeCrossCrate::Yes
423    ),
424    ungated!(proc_macro, Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::No),
425    ungated!(
426        proc_macro_derive, Normal, template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)"),
427        ErrorFollowing, EncodeCrossCrate::No,
428    ),
429    ungated!(proc_macro_attribute, Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::No),
430
431    // Lints:
432    ungated!(
433        warn, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#),
434        DuplicatesOk, EncodeCrossCrate::No,
435    ),
436    ungated!(
437        allow, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#),
438        DuplicatesOk, EncodeCrossCrate::No,
439    ),
440    ungated!(
441        expect, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#),
442        DuplicatesOk, EncodeCrossCrate::No,
443    ),
444    ungated!(
445        forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#),
446        DuplicatesOk, EncodeCrossCrate::No
447    ),
448    ungated!(
449        deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#),
450        DuplicatesOk, EncodeCrossCrate::No
451    ),
452    ungated!(
453        must_use, Normal, template!(Word, NameValueStr: "reason"),
454        FutureWarnFollowing, EncodeCrossCrate::Yes
455    ),
456    gated!(
457        must_not_suspend, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing,
458        EncodeCrossCrate::Yes, experimental!(must_not_suspend)
459    ),
460    ungated!(
461        deprecated, Normal,
462        template!(
463            Word,
464            List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#,
465            NameValueStr: "reason"
466        ),
467        ErrorFollowing, EncodeCrossCrate::Yes
468    ),
469
470    // Crate properties:
471    ungated!(
472        crate_name, CrateLevel, template!(NameValueStr: "name"), FutureWarnFollowing,
473        EncodeCrossCrate::No,
474    ),
475    ungated!(
476        crate_type, CrateLevel, template!(NameValueStr: "bin|lib|..."), DuplicatesOk,
477        EncodeCrossCrate::No,
478    ),
479
480    // ABI, linking, symbols, and FFI
481    ungated!(
482        link, Normal,
483        template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...", /*opt*/ import_name_type = "decorated|noprefix|undecorated""#),
484        DuplicatesOk,
485        EncodeCrossCrate::No,
486    ),
487    ungated!(
488        link_name, Normal, template!(NameValueStr: "name"),
489        FutureWarnPreceding, EncodeCrossCrate::Yes
490    ),
491    ungated!(no_link, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No),
492    ungated!(repr, Normal, template!(List: "C"), DuplicatesOk, EncodeCrossCrate::No),
493    // FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
494    gated!(rustc_align, Normal, template!(List: "alignment"), DuplicatesOk, EncodeCrossCrate::No, fn_align, experimental!(rustc_align)),
495    ungated!(unsafe(Edition2024) export_name, Normal, template!(NameValueStr: "name"), FutureWarnPreceding, EncodeCrossCrate::No),
496    ungated!(unsafe(Edition2024) link_section, Normal, template!(NameValueStr: "name"), FutureWarnPreceding, EncodeCrossCrate::No),
497    ungated!(unsafe(Edition2024) no_mangle, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No),
498    ungated!(used, Normal, template!(Word, List: "compiler|linker"), WarnFollowing, EncodeCrossCrate::No),
499    ungated!(link_ordinal, Normal, template!(List: "ordinal"), ErrorPreceding, EncodeCrossCrate::Yes),
500    ungated!(unsafe naked, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No),
501
502    // Limits:
503    ungated!(
504        recursion_limit, CrateLevel, template!(NameValueStr: "N"), FutureWarnFollowing,
505        EncodeCrossCrate::No
506    ),
507    ungated!(
508        type_length_limit, CrateLevel, template!(NameValueStr: "N"), FutureWarnFollowing,
509        EncodeCrossCrate::No
510    ),
511    gated!(
512        move_size_limit, CrateLevel, template!(NameValueStr: "N"), ErrorFollowing,
513        EncodeCrossCrate::No, large_assignments, experimental!(move_size_limit)
514    ),
515
516    // Entry point:
517    ungated!(no_main, CrateLevel, template!(Word), WarnFollowing, EncodeCrossCrate::No),
518
519    // Modules, prelude, and resolution:
520    ungated!(path, Normal, template!(NameValueStr: "file"), FutureWarnFollowing, EncodeCrossCrate::No),
521    ungated!(no_std, CrateLevel, template!(Word), WarnFollowing, EncodeCrossCrate::No),
522    ungated!(no_implicit_prelude, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No),
523    ungated!(non_exhaustive, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes),
524
525    // Runtime
526    ungated!(
527        windows_subsystem, CrateLevel,
528        template!(NameValueStr: "windows|console"), FutureWarnFollowing,
529        EncodeCrossCrate::No
530    ),
531    ungated!(panic_handler, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes), // RFC 2070
532
533    // Code generation:
534    ungated!(inline, Normal, template!(Word, List: "always|never"), FutureWarnFollowing, EncodeCrossCrate::No),
535    ungated!(cold, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No),
536    ungated!(no_builtins, CrateLevel, template!(Word), WarnFollowing, EncodeCrossCrate::Yes),
537    ungated!(
538        target_feature, Normal, template!(List: r#"enable = "name""#),
539        DuplicatesOk, EncodeCrossCrate::No,
540    ),
541    ungated!(track_caller, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes),
542    ungated!(instruction_set, Normal, template!(List: "set"), ErrorPreceding, EncodeCrossCrate::No),
543    gated!(
544        no_sanitize, Normal,
545        template!(List: "address, kcfi, memory, thread"), DuplicatesOk,
546        EncodeCrossCrate::No, experimental!(no_sanitize)
547    ),
548    gated!(
549        coverage, Normal, template!(OneOf: &[sym::off, sym::on]),
550        ErrorPreceding, EncodeCrossCrate::No,
551        coverage_attribute, experimental!(coverage)
552    ),
553
554    ungated!(
555        doc, Normal, template!(List: "hidden|inline|...", NameValueStr: "string"), DuplicatesOk,
556        EncodeCrossCrate::Yes
557    ),
558
559    // Debugging
560    ungated!(
561        debugger_visualizer, Normal,
562        template!(List: r#"natvis_file = "...", gdb_script_file = "...""#),
563        DuplicatesOk, EncodeCrossCrate::No
564    ),
565    ungated!(collapse_debuginfo, Normal, template!(List: "no|external|yes"), ErrorFollowing,
566        EncodeCrossCrate::Yes
567    ),
568
569    // ==========================================================================
570    // Unstable attributes:
571    // ==========================================================================
572
573    // Linking:
574    gated!(
575        export_stable, Normal, template!(Word), WarnFollowing,
576        EncodeCrossCrate::No, experimental!(export_stable)
577    ),
578
579    // Testing:
580    gated!(
581        test_runner, CrateLevel, template!(List: "path"), ErrorFollowing,
582        EncodeCrossCrate::Yes, custom_test_frameworks,
583        "custom test frameworks are an unstable feature",
584    ),
585    // RFC #1268
586    gated!(
587        marker, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
588        marker_trait_attr, experimental!(marker)
589    ),
590    gated!(
591        thread_local, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
592        "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
593    ),
594    gated!(
595        no_core, CrateLevel, template!(Word), WarnFollowing,
596        EncodeCrossCrate::No, experimental!(no_core)
597    ),
598    // RFC 2412
599    gated!(
600        optimize, Normal, template!(List: "none|size|speed"), ErrorPreceding,
601        EncodeCrossCrate::No, optimize_attribute, experimental!(optimize)
602    ),
603
604    gated!(
605        unsafe ffi_pure, Normal, template!(Word), WarnFollowing,
606        EncodeCrossCrate::No, experimental!(ffi_pure)
607    ),
608    gated!(
609        unsafe ffi_const, Normal, template!(Word), WarnFollowing,
610        EncodeCrossCrate::No, experimental!(ffi_const)
611    ),
612    gated!(
613        register_tool, CrateLevel, template!(List: "tool1, tool2, ..."), DuplicatesOk,
614        EncodeCrossCrate::No, experimental!(register_tool),
615    ),
616
617    // RFC 2632
618    // FIXME(const_trait_impl) remove this
619    gated!(
620        const_trait, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No, const_trait_impl,
621        "`const_trait` is a temporary placeholder for marking a trait that is suitable for `const` \
622        `impls` and all default bodies as `const`, which may be removed or renamed in the \
623        future."
624    ),
625    // lang-team MCP 147
626    gated!(
627        deprecated_safe, Normal, template!(List: r#"since = "version", note = "...""#), ErrorFollowing,
628        EncodeCrossCrate::Yes, experimental!(deprecated_safe),
629    ),
630
631    // `#[cfi_encoding = ""]`
632    gated!(
633        cfi_encoding, Normal, template!(NameValueStr: "encoding"), ErrorPreceding,
634        EncodeCrossCrate::Yes, experimental!(cfi_encoding)
635    ),
636
637    // `#[coroutine]` attribute to be applied to closures to make them coroutines instead
638    gated!(
639        coroutine, Normal, template!(Word), ErrorFollowing,
640        EncodeCrossCrate::No, coroutines, experimental!(coroutine)
641    ),
642
643    // RFC 3543
644    // `#[patchable_function_entry(prefix_nops = m, entry_nops = n)]`
645    gated!(
646        patchable_function_entry, Normal, template!(List: "prefix_nops = m, entry_nops = n"), ErrorPreceding,
647        EncodeCrossCrate::Yes, experimental!(patchable_function_entry)
648    ),
649
650    // Probably temporary component of min_generic_const_args.
651    // `#[type_const] const ASSOC: usize;`
652    gated!(
653        type_const, Normal, template!(Word), ErrorFollowing,
654        EncodeCrossCrate::Yes, min_generic_const_args, experimental!(type_const),
655    ),
656
657    // The `#[loop_match]` and `#[const_continue]` attributes are part of the
658    // lang experiment for RFC 3720 tracked in:
659    //
660    // - https://github.com/rust-lang/rust/issues/132306
661    gated!(
662        const_continue, Normal, template!(Word), ErrorFollowing,
663        EncodeCrossCrate::No, loop_match, experimental!(const_continue)
664    ),
665    gated!(
666        loop_match, Normal, template!(Word), ErrorFollowing,
667        EncodeCrossCrate::No, loop_match, experimental!(loop_match)
668    ),
669
670    // ==========================================================================
671    // Internal attributes: Stability, deprecation, and unsafe:
672    // ==========================================================================
673
674    ungated!(
675        feature, CrateLevel,
676        template!(List: "name1, name2, ..."), DuplicatesOk, EncodeCrossCrate::No,
677    ),
678    // DuplicatesOk since it has its own validation
679    ungated!(
680        stable, Normal,
681        template!(List: r#"feature = "name", since = "version""#), DuplicatesOk, EncodeCrossCrate::No,
682    ),
683    ungated!(
684        unstable, Normal,
685        template!(List: r#"feature = "name", reason = "...", issue = "N""#), DuplicatesOk,
686        EncodeCrossCrate::Yes
687    ),
688    ungated!(
689        unstable_feature_bound, Normal, template!(Word, List: "feat1, feat2, ..."),
690        DuplicatesOk, EncodeCrossCrate::No,
691    ),
692    ungated!(
693        rustc_const_unstable, Normal, template!(List: r#"feature = "name""#),
694        DuplicatesOk, EncodeCrossCrate::Yes
695    ),
696    ungated!(
697        rustc_const_stable, Normal,
698        template!(List: r#"feature = "name""#), DuplicatesOk, EncodeCrossCrate::No,
699    ),
700    ungated!(
701        rustc_default_body_unstable, Normal,
702        template!(List: r#"feature = "name", reason = "...", issue = "N""#),
703        DuplicatesOk, EncodeCrossCrate::No
704    ),
705    gated!(
706        allow_internal_unstable, Normal, template!(Word, List: "feat1, feat2, ..."),
707        DuplicatesOk, EncodeCrossCrate::Yes,
708        "allow_internal_unstable side-steps feature gating and stability checks",
709    ),
710    gated!(
711        allow_internal_unsafe, Normal, template!(Word), WarnFollowing,
712        EncodeCrossCrate::No, "allow_internal_unsafe side-steps the unsafe_code lint",
713    ),
714    rustc_attr!(
715        rustc_allowed_through_unstable_modules, Normal, template!(NameValueStr: "deprecation message"),
716        WarnFollowing, EncodeCrossCrate::No,
717        "rustc_allowed_through_unstable_modules special cases accidental stabilizations of stable items \
718        through unstable paths"
719    ),
720    rustc_attr!(
721        rustc_deprecated_safe_2024, Normal, template!(List: r#"audit_that = "...""#),
722        ErrorFollowing, EncodeCrossCrate::Yes,
723        "`#[rustc_deprecated_safe_2024]` is used to declare functions unsafe across the edition 2024 boundary",
724    ),
725    rustc_attr!(
726        rustc_pub_transparent, Normal, template!(Word),
727        ErrorFollowing, EncodeCrossCrate::Yes,
728        "used internally to mark types with a `transparent` representation when it is guaranteed by the documentation",
729    ),
730
731
732    // ==========================================================================
733    // Internal attributes: Type system related:
734    // ==========================================================================
735
736    gated!(fundamental, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes, experimental!(fundamental)),
737    gated!(
738        may_dangle, Normal, template!(Word), WarnFollowing,
739        EncodeCrossCrate::No, dropck_eyepatch,
740        "`may_dangle` has unstable semantics and may be removed in the future",
741    ),
742
743    rustc_attr!(
744        rustc_never_type_options,
745        Normal,
746        template!(List: r#"/*opt*/ fallback = "unit|niko|never|no""#),
747        ErrorFollowing,
748        EncodeCrossCrate::No,
749        "`rustc_never_type_options` is used to experiment with never type fallback and work on \
750         never type stabilization"
751    ),
752
753    // ==========================================================================
754    // Internal attributes: Runtime related:
755    // ==========================================================================
756
757    rustc_attr!(
758        rustc_allocator, Normal, template!(Word), WarnFollowing,
759        EncodeCrossCrate::No,
760    ),
761    rustc_attr!(
762        rustc_nounwind, Normal, template!(Word), WarnFollowing,
763        EncodeCrossCrate::No,
764    ),
765    rustc_attr!(
766        rustc_reallocator, Normal, template!(Word), WarnFollowing,
767        EncodeCrossCrate::No,
768    ),
769    rustc_attr!(
770        rustc_deallocator, Normal, template!(Word), WarnFollowing,
771        EncodeCrossCrate::No,
772    ),
773    rustc_attr!(
774        rustc_allocator_zeroed, Normal, template!(Word), WarnFollowing,
775        EncodeCrossCrate::No,
776    ),
777    gated!(
778        default_lib_allocator, Normal, template!(Word), WarnFollowing,
779        EncodeCrossCrate::No, allocator_internals, experimental!(default_lib_allocator),
780    ),
781    gated!(
782        needs_allocator, Normal, template!(Word), WarnFollowing,
783        EncodeCrossCrate::No, allocator_internals, experimental!(needs_allocator),
784    ),
785    gated!(
786        panic_runtime, CrateLevel, template!(Word), WarnFollowing,
787        EncodeCrossCrate::No, experimental!(panic_runtime)
788    ),
789    gated!(
790        needs_panic_runtime, CrateLevel, template!(Word), WarnFollowing,
791        EncodeCrossCrate::No, experimental!(needs_panic_runtime)
792    ),
793    gated!(
794        compiler_builtins, CrateLevel, template!(Word), WarnFollowing,
795        EncodeCrossCrate::No,
796        "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \
797        which contains compiler-rt intrinsics and will never be stable",
798    ),
799    gated!(
800        profiler_runtime, CrateLevel, template!(Word), WarnFollowing,
801        EncodeCrossCrate::No,
802        "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \
803        which contains the profiler runtime and will never be stable",
804    ),
805
806    // ==========================================================================
807    // Internal attributes, Linkage:
808    // ==========================================================================
809
810    gated!(
811        linkage, Normal, template!(NameValueStr: "external|internal|..."),
812        ErrorPreceding, EncodeCrossCrate::No,
813        "the `linkage` attribute is experimental and not portable across platforms",
814    ),
815    rustc_attr!(
816        rustc_std_internal_symbol, Normal, template!(Word), WarnFollowing,
817        EncodeCrossCrate::No,
818    ),
819
820    // ==========================================================================
821    // Internal attributes, Macro related:
822    // ==========================================================================
823
824    rustc_attr!(
825        rustc_builtin_macro, Normal,
826        template!(Word, List: "name, /*opt*/ attributes(name1, name2, ...)"), ErrorFollowing,
827        EncodeCrossCrate::Yes,
828    ),
829    rustc_attr!(
830        rustc_proc_macro_decls, Normal, template!(Word), WarnFollowing,
831        EncodeCrossCrate::No,
832    ),
833    rustc_attr!(
834        rustc_macro_transparency, Normal,
835        template!(NameValueStr: "transparent|semiopaque|opaque"), ErrorFollowing,
836        EncodeCrossCrate::Yes, "used internally for testing macro hygiene",
837    ),
838    rustc_attr!(
839        rustc_autodiff, Normal,
840        template!(Word, List: r#""...""#), DuplicatesOk,
841        EncodeCrossCrate::Yes,
842    ),
843    // Traces that are left when `cfg` and `cfg_attr` attributes are expanded.
844    // The attributes are not gated, to avoid stability errors, but they cannot be used in stable
845    // or unstable code directly because `sym::cfg_(attr_)trace` are not valid identifiers, they
846    // can only be generated by the compiler.
847    ungated!(
848        cfg_trace, Normal, template!(Word /* irrelevant */), DuplicatesOk,
849        EncodeCrossCrate::No
850    ),
851    ungated!(
852        cfg_attr_trace, Normal, template!(Word /* irrelevant */), DuplicatesOk,
853        EncodeCrossCrate::No
854    ),
855
856    // ==========================================================================
857    // Internal attributes, Diagnostics related:
858    // ==========================================================================
859
860    rustc_attr!(
861        rustc_on_unimplemented, Normal,
862        template!(
863            List: r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#,
864            NameValueStr: "message"
865        ),
866        ErrorFollowing, EncodeCrossCrate::Yes,
867        "see `#[diagnostic::on_unimplemented]` for the stable equivalent of this attribute"
868    ),
869    rustc_attr!(
870        rustc_confusables, Normal,
871        template!(List: r#""name1", "name2", ..."#),
872        ErrorFollowing, EncodeCrossCrate::Yes,
873    ),
874    // Enumerates "identity-like" conversion methods to suggest on type mismatch.
875    rustc_attr!(
876        rustc_conversion_suggestion, Normal, template!(Word),
877        WarnFollowing, EncodeCrossCrate::Yes,
878    ),
879    // Prevents field reads in the marked trait or method to be considered
880    // during dead code analysis.
881    rustc_attr!(
882        rustc_trivial_field_reads, Normal, template!(Word),
883        WarnFollowing, EncodeCrossCrate::Yes,
884    ),
885    // Used by the `rustc::potential_query_instability` lint to warn methods which
886    // might not be stable during incremental compilation.
887    rustc_attr!(
888        rustc_lint_query_instability, Normal, template!(Word),
889        WarnFollowing, EncodeCrossCrate::Yes,
890    ),
891    // Used by the `rustc::untracked_query_information` lint to warn methods which
892    // might not be stable during incremental compilation.
893    rustc_attr!(
894        rustc_lint_untracked_query_information, Normal, template!(Word),
895        WarnFollowing, EncodeCrossCrate::Yes,
896    ),
897    // Used by the `rustc::diagnostic_outside_of_impl` lints to assist in changes to diagnostic
898    // APIs. Any function with this attribute will be checked by that lint.
899    rustc_attr!(
900        rustc_lint_diagnostics, Normal, template!(Word),
901        WarnFollowing, EncodeCrossCrate::Yes,
902    ),
903    // Used by the `rustc::bad_opt_access` lint to identify `DebuggingOptions` and `CodegenOptions`
904    // types (as well as any others in future).
905    rustc_attr!(
906        rustc_lint_opt_ty, Normal, template!(Word),
907        WarnFollowing, EncodeCrossCrate::Yes,
908    ),
909    // Used by the `rustc::bad_opt_access` lint on fields
910    // types (as well as any others in future).
911    rustc_attr!(
912        rustc_lint_opt_deny_field_access, Normal, template!(List: "message"),
913        WarnFollowing, EncodeCrossCrate::Yes,
914    ),
915
916    // ==========================================================================
917    // Internal attributes, Const related:
918    // ==========================================================================
919
920    rustc_attr!(
921        rustc_promotable, Normal, template!(Word), WarnFollowing,
922        EncodeCrossCrate::No, ),
923    rustc_attr!(
924        rustc_legacy_const_generics, Normal, template!(List: "N"), ErrorFollowing,
925        EncodeCrossCrate::Yes,
926    ),
927    // Do not const-check this function's body. It will always get replaced during CTFE via `hook_special_const_fn`.
928    rustc_attr!(
929        rustc_do_not_const_check, Normal, template!(Word), WarnFollowing,
930        EncodeCrossCrate::Yes, "`#[rustc_do_not_const_check]` skips const-check for this function's body",
931    ),
932    rustc_attr!(
933        rustc_const_panic_str, Normal, template!(Word), WarnFollowing,
934        EncodeCrossCrate::Yes, "`#[rustc_const_panic_str]` ensures the argument to this function is &&str during const-check",
935    ),
936    rustc_attr!(
937        rustc_const_stable_indirect, Normal,
938        template!(Word),
939        WarnFollowing,
940        EncodeCrossCrate::No,
941        "this is an internal implementation detail",
942    ),
943    rustc_attr!(
944        rustc_intrinsic_const_stable_indirect, Normal,
945        template!(Word), WarnFollowing, EncodeCrossCrate::No,  "this is an internal implementation detail",
946    ),
947    gated!(
948        rustc_allow_const_fn_unstable, Normal,
949        template!(Word, List: "feat1, feat2, ..."), DuplicatesOk, EncodeCrossCrate::No,
950        "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
951    ),
952
953    // ==========================================================================
954    // Internal attributes, Layout related:
955    // ==========================================================================
956
957    rustc_attr!(
958        rustc_layout_scalar_valid_range_start, Normal, template!(List: "value"), ErrorFollowing,
959        EncodeCrossCrate::Yes,
960        "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
961        niche optimizations in the standard library",
962    ),
963    rustc_attr!(
964        rustc_layout_scalar_valid_range_end, Normal, template!(List: "value"), ErrorFollowing,
965        EncodeCrossCrate::Yes,
966        "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
967        niche optimizations in the standard library",
968    ),
969    rustc_attr!(
970        rustc_nonnull_optimization_guaranteed, Normal, template!(Word), WarnFollowing,
971        EncodeCrossCrate::Yes,
972        "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document \
973        guaranteed niche optimizations in the standard library",
974        "the compiler does not even check whether the type indeed is being non-null-optimized; \
975        it is your responsibility to ensure that the attribute is only used on types that are optimized",
976    ),
977
978    // ==========================================================================
979    // Internal attributes, Misc:
980    // ==========================================================================
981    gated!(
982        lang, Normal, template!(NameValueStr: "name"), DuplicatesOk, EncodeCrossCrate::No, lang_items,
983        "lang items are subject to change",
984    ),
985    rustc_attr!(
986        rustc_as_ptr, Normal, template!(Word), ErrorFollowing,
987        EncodeCrossCrate::Yes,
988        "`#[rustc_as_ptr]` is used to mark functions returning pointers to their inner allocations."
989    ),
990    rustc_attr!(
991        rustc_pass_by_value, Normal, template!(Word), ErrorFollowing,
992        EncodeCrossCrate::Yes,
993        "`#[rustc_pass_by_value]` is used to mark types that must be passed by value instead of reference."
994    ),
995    rustc_attr!(
996        rustc_never_returns_null_ptr, Normal, template!(Word), ErrorFollowing,
997        EncodeCrossCrate::Yes,
998        "`#[rustc_never_returns_null_ptr]` is used to mark functions returning non-null pointers."
999    ),
1000    rustc_attr!(
1001        rustc_no_implicit_autorefs, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes,
1002        "`#[rustc_no_implicit_autorefs]` is used to mark functions for which an autoref to the dereference of a raw pointer should not be used as an argument."
1003    ),
1004    rustc_attr!(
1005        rustc_coherence_is_core, AttributeType::CrateLevel, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1006        "`#![rustc_coherence_is_core]` allows inherent methods on builtin types, only intended to be used in `core`."
1007    ),
1008    rustc_attr!(
1009        rustc_coinductive, AttributeType::Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1010        "`#[rustc_coinductive]` changes a trait to be coinductive, allowing cycles in the trait solver."
1011    ),
1012    rustc_attr!(
1013        rustc_allow_incoherent_impl, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1014        "`#[rustc_allow_incoherent_impl]` has to be added to all impl items of an incoherent inherent impl."
1015    ),
1016    rustc_attr!(
1017        rustc_preserve_ub_checks, AttributeType::CrateLevel, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1018        "`#![rustc_preserve_ub_checks]` prevents the designated crate from evaluating whether UB checks are enabled when optimizing MIR",
1019    ),
1020    rustc_attr!(
1021        rustc_deny_explicit_impl,
1022        AttributeType::Normal,
1023        template!(Word),
1024        ErrorFollowing,
1025        EncodeCrossCrate::No,
1026        "`#[rustc_deny_explicit_impl]` enforces that a trait can have no user-provided impls"
1027    ),
1028    rustc_attr!(
1029        rustc_do_not_implement_via_object,
1030        AttributeType::Normal,
1031        template!(Word),
1032        ErrorFollowing,
1033        EncodeCrossCrate::No,
1034        "`#[rustc_do_not_implement_via_object]` opts out of the automatic trait impl for trait objects \
1035        (`impl Trait for dyn Trait`)"
1036    ),
1037    rustc_attr!(
1038        rustc_has_incoherent_inherent_impls, AttributeType::Normal, template!(Word),
1039        ErrorFollowing, EncodeCrossCrate::Yes,
1040        "`#[rustc_has_incoherent_inherent_impls]` allows the addition of incoherent inherent impls for \
1041         the given type by annotating all impl items with `#[rustc_allow_incoherent_impl]`."
1042    ),
1043
1044    BuiltinAttribute {
1045        name: sym::rustc_diagnostic_item,
1046        // FIXME: This can be `true` once we always use `tcx.is_diagnostic_item`.
1047        encode_cross_crate: EncodeCrossCrate::Yes,
1048        type_: Normal,
1049        safety: AttributeSafety::Normal,
1050        template: template!(NameValueStr: "name"),
1051        duplicates: ErrorFollowing,
1052        gate: Gated{
1053            feature: sym::rustc_attrs,
1054            message: "use of an internal attribute",
1055            check: Features::rustc_attrs,
1056            notes: &["the `#[rustc_diagnostic_item]` attribute allows the compiler to reference types \
1057            from the standard library for diagnostic purposes"],
1058        },
1059    },
1060    gated!(
1061        // Used in resolve:
1062        prelude_import, Normal, template!(Word), WarnFollowing,
1063        EncodeCrossCrate::No, "`#[prelude_import]` is for use by rustc only",
1064    ),
1065    gated!(
1066        rustc_paren_sugar, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1067        unboxed_closures, "unboxed_closures are still evolving",
1068    ),
1069    rustc_attr!(
1070        rustc_inherit_overflow_checks, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1071        "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \
1072        overflow checking behavior of several functions in the standard library that are inlined \
1073        across crates",
1074    ),
1075    rustc_attr!(
1076        rustc_reservation_impl, Normal,
1077        template!(NameValueStr: "reservation message"), ErrorFollowing, EncodeCrossCrate::Yes,
1078        "the `#[rustc_reservation_impl]` attribute is internally used \
1079        for reserving `impl<T> From<!> for T` as part of the effort to stabilize `!`"
1080    ),
1081    rustc_attr!(
1082        rustc_test_marker, Normal, template!(NameValueStr: "name"), WarnFollowing,
1083        EncodeCrossCrate::No, "the `#[rustc_test_marker]` attribute is used internally to track tests",
1084    ),
1085    rustc_attr!(
1086        rustc_unsafe_specialization_marker, Normal, template!(Word),
1087        WarnFollowing, EncodeCrossCrate::No,
1088        "the `#[rustc_unsafe_specialization_marker]` attribute is used to check specializations"
1089    ),
1090    rustc_attr!(
1091        rustc_specialization_trait, Normal, template!(Word),
1092        WarnFollowing, EncodeCrossCrate::No,
1093        "the `#[rustc_specialization_trait]` attribute is used to check specializations"
1094    ),
1095    rustc_attr!(
1096        rustc_main, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1097        "the `#[rustc_main]` attribute is used internally to specify test entry point function",
1098    ),
1099    rustc_attr!(
1100        rustc_skip_during_method_dispatch, Normal, template!(List: "array, boxed_slice"), ErrorFollowing,
1101        EncodeCrossCrate::No,
1102        "the `#[rustc_skip_during_method_dispatch]` attribute is used to exclude a trait \
1103        from method dispatch when the receiver is of the following type, for compatibility in \
1104        editions < 2021 (array) or editions < 2024 (boxed_slice)."
1105    ),
1106    rustc_attr!(
1107        rustc_must_implement_one_of, Normal, template!(List: "function1, function2, ..."),
1108        ErrorFollowing, EncodeCrossCrate::No,
1109        "the `#[rustc_must_implement_one_of]` attribute is used to change minimal complete \
1110        definition of a trait. Its syntax and semantics are highly experimental and will be \
1111        subject to change before stabilization",
1112    ),
1113    rustc_attr!(
1114        rustc_doc_primitive, Normal, template!(NameValueStr: "primitive name"), ErrorFollowing,
1115        EncodeCrossCrate::Yes, "the `#[rustc_doc_primitive]` attribute is used by the standard library \
1116        to provide a way to generate documentation for primitive types",
1117    ),
1118    gated!(
1119        rustc_intrinsic, Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes, intrinsics,
1120        "the `#[rustc_intrinsic]` attribute is used to declare intrinsics as function items",
1121    ),
1122    rustc_attr!(
1123        rustc_no_mir_inline, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes,
1124        "`#[rustc_no_mir_inline]` prevents the MIR inliner from inlining a function while not affecting codegen"
1125    ),
1126    rustc_attr!(
1127        rustc_force_inline, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing, EncodeCrossCrate::Yes,
1128        "`#[rustc_force_inline]` forces a free function to be inlined"
1129    ),
1130
1131    // ==========================================================================
1132    // Internal attributes, Testing:
1133    // ==========================================================================
1134
1135    rustc_attr!(TEST, rustc_effective_visibility, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes),
1136    rustc_attr!(
1137        TEST, rustc_outlives, Normal, template!(Word),
1138        WarnFollowing, EncodeCrossCrate::No
1139    ),
1140    rustc_attr!(
1141        TEST, rustc_capture_analysis, Normal, template!(Word),
1142        WarnFollowing, EncodeCrossCrate::No
1143    ),
1144    rustc_attr!(
1145        TEST, rustc_insignificant_dtor, Normal, template!(Word),
1146        WarnFollowing, EncodeCrossCrate::Yes
1147    ),
1148    rustc_attr!(
1149        TEST, rustc_no_implicit_bounds, CrateLevel, template!(Word),
1150        WarnFollowing, EncodeCrossCrate::No
1151    ),
1152    rustc_attr!(
1153        TEST, rustc_strict_coherence, Normal, template!(Word),
1154        WarnFollowing, EncodeCrossCrate::Yes
1155    ),
1156    rustc_attr!(
1157        TEST, rustc_variance, Normal, template!(Word),
1158        WarnFollowing, EncodeCrossCrate::No
1159    ),
1160    rustc_attr!(
1161        TEST, rustc_variance_of_opaques, Normal, template!(Word),
1162        WarnFollowing, EncodeCrossCrate::No
1163    ),
1164    rustc_attr!(
1165        TEST, rustc_hidden_type_of_opaques, Normal, template!(Word),
1166        WarnFollowing, EncodeCrossCrate::No
1167    ),
1168    rustc_attr!(
1169        TEST, rustc_layout, Normal, template!(List: "field1, field2, ..."),
1170        WarnFollowing, EncodeCrossCrate::Yes
1171    ),
1172    rustc_attr!(
1173        TEST, rustc_abi, Normal, template!(List: "field1, field2, ..."),
1174        WarnFollowing, EncodeCrossCrate::No
1175    ),
1176    rustc_attr!(
1177        TEST, rustc_regions, Normal, template!(Word),
1178        WarnFollowing, EncodeCrossCrate::No
1179    ),
1180    rustc_attr!(
1181        TEST, rustc_delayed_bug_from_inside_query, Normal,
1182        template!(Word),
1183        WarnFollowing, EncodeCrossCrate::No
1184    ),
1185    rustc_attr!(
1186        TEST, rustc_dump_user_args, Normal, template!(Word),
1187        WarnFollowing, EncodeCrossCrate::No
1188    ),
1189    rustc_attr!(
1190        TEST, rustc_evaluate_where_clauses, Normal, template!(Word), WarnFollowing,
1191        EncodeCrossCrate::Yes
1192    ),
1193    rustc_attr!(
1194        TEST, rustc_if_this_changed, Normal, template!(Word, List: "DepNode"), DuplicatesOk,
1195        EncodeCrossCrate::No
1196    ),
1197    rustc_attr!(
1198        TEST, rustc_then_this_would_need, Normal, template!(List: "DepNode"), DuplicatesOk,
1199        EncodeCrossCrate::No
1200    ),
1201    rustc_attr!(
1202        TEST, rustc_clean, Normal,
1203        template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
1204        DuplicatesOk, EncodeCrossCrate::No
1205    ),
1206    rustc_attr!(
1207        TEST, rustc_partition_reused, Normal,
1208        template!(List: r#"cfg = "...", module = "...""#), DuplicatesOk, EncodeCrossCrate::No
1209    ),
1210    rustc_attr!(
1211        TEST, rustc_partition_codegened, Normal,
1212        template!(List: r#"cfg = "...", module = "...""#), DuplicatesOk, EncodeCrossCrate::No
1213    ),
1214    rustc_attr!(
1215        TEST, rustc_expected_cgu_reuse, Normal,
1216        template!(List: r#"cfg = "...", module = "...", kind = "...""#), DuplicatesOk,
1217        EncodeCrossCrate::No
1218    ),
1219    rustc_attr!(
1220        TEST, rustc_symbol_name, Normal, template!(Word),
1221        WarnFollowing, EncodeCrossCrate::No
1222    ),
1223    rustc_attr!(
1224        TEST, rustc_def_path, Normal, template!(Word),
1225        WarnFollowing, EncodeCrossCrate::No
1226    ),
1227    rustc_attr!(
1228        TEST, rustc_mir, Normal, template!(List: "arg1, arg2, ..."),
1229        DuplicatesOk, EncodeCrossCrate::Yes
1230    ),
1231    gated!(
1232        custom_mir, Normal, template!(List: r#"dialect = "...", phase = "...""#),
1233        ErrorFollowing, EncodeCrossCrate::No,
1234        "the `#[custom_mir]` attribute is just used for the Rust test suite",
1235    ),
1236    rustc_attr!(
1237        TEST, rustc_dump_item_bounds, Normal, template!(Word),
1238        WarnFollowing, EncodeCrossCrate::No
1239    ),
1240    rustc_attr!(
1241        TEST, rustc_dump_predicates, Normal, template!(Word),
1242        WarnFollowing, EncodeCrossCrate::No
1243    ),
1244    rustc_attr!(
1245        TEST, rustc_dump_def_parents, Normal, template!(Word),
1246        WarnFollowing, EncodeCrossCrate::No
1247    ),
1248    rustc_attr!(
1249        TEST, rustc_object_lifetime_default, Normal, template!(Word),
1250        WarnFollowing, EncodeCrossCrate::No
1251    ),
1252    rustc_attr!(
1253        TEST, rustc_dump_vtable, Normal, template!(Word),
1254        WarnFollowing, EncodeCrossCrate::No
1255    ),
1256    rustc_attr!(
1257        TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/),
1258        DuplicatesOk, EncodeCrossCrate::No
1259    ),
1260    gated!(
1261        omit_gdb_pretty_printer_section, Normal, template!(Word),
1262        WarnFollowing, EncodeCrossCrate::No,
1263        "the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite",
1264    ),
1265    rustc_attr!(
1266        TEST, pattern_complexity_limit, CrateLevel, template!(NameValueStr: "N"),
1267        ErrorFollowing, EncodeCrossCrate::No,
1268    ),
1269];
1270
1271pub fn is_builtin_attr_name(name: Symbol) -> bool {
1272    BUILTIN_ATTRIBUTE_MAP.get(&name).is_some()
1273}
1274
1275/// Whether this builtin attribute is encoded cross crate.
1276/// This means it can be used cross crate.
1277pub fn encode_cross_crate(name: Symbol) -> bool {
1278    if let Some(attr) = BUILTIN_ATTRIBUTE_MAP.get(&name) {
1279        attr.encode_cross_crate == EncodeCrossCrate::Yes
1280    } else {
1281        true
1282    }
1283}
1284
1285pub fn is_valid_for_get_attr(name: Symbol) -> bool {
1286    BUILTIN_ATTRIBUTE_MAP.get(&name).is_some_and(|attr| match attr.duplicates {
1287        WarnFollowing | ErrorFollowing | ErrorPreceding | FutureWarnFollowing
1288        | FutureWarnPreceding => true,
1289        DuplicatesOk | WarnFollowingWordOnly => false,
1290    })
1291}
1292
1293pub static BUILTIN_ATTRIBUTE_MAP: LazyLock<FxHashMap<Symbol, &BuiltinAttribute>> =
1294    LazyLock::new(|| {
1295        let mut map = FxHashMap::default();
1296        for attr in BUILTIN_ATTRIBUTES.iter() {
1297            if map.insert(attr.name, attr).is_some() {
1298                panic!("duplicate builtin attribute `{}`", attr.name);
1299            }
1300        }
1301        map
1302    });
1303
1304pub fn is_stable_diagnostic_attribute(sym: Symbol, _features: &Features) -> bool {
1305    match sym {
1306        sym::on_unimplemented | sym::do_not_recommend => true,
1307        _ => false,
1308    }
1309}
rustc_feature/builtin_attrs.rs

rustc_feature/
builtin_attrs.rs
