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 [&'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 [&'static str]>,
130    /// A link to the document for this attribute.
131    pub docs: Option<&'static str>,
132}
133
134impl AttributeTemplate {
135    pub fn suggestions(&self, inner: bool, name: impl std::fmt::Display) -> Vec<String> {
136        let mut suggestions = vec![];
137        let inner = if inner { "!" } else { "" };
138        if self.word {
139            suggestions.push(format!("#{inner}[{name}]"));
140        }
141        if let Some(descr) = self.list {
142            for descr in descr {
143                suggestions.push(format!("#{inner}[{name}({descr})]"));
144            }
145        }
146        suggestions.extend(self.one_of.iter().map(|&word| format!("#{inner}[{name}({word})]")));
147        if let Some(descr) = self.name_value_str {
148            for descr in descr {
149                suggestions.push(format!("#{inner}[{name} = \"{descr}\"]"));
150            }
151        }
152        suggestions.sort();
153
154        suggestions
155    }
156}
157
158/// How to handle multiple duplicate attributes on the same item.
159#[derive(Clone, Copy, Default)]
160pub enum AttributeDuplicates {
161    /// Duplicates of this attribute are allowed.
162    ///
163    /// This should only be used with attributes where duplicates have semantic
164    /// meaning, or some kind of "additive" behavior. For example, `#[warn(..)]`
165    /// can be specified multiple times, and it combines all the entries. Or use
166    /// this if there is validation done elsewhere.
167    #[default]
168    DuplicatesOk,
169    /// Duplicates after the first attribute will be an unused_attribute warning.
170    ///
171    /// This is usually used for "word" attributes, where they are used as a
172    /// boolean marker, like `#[used]`. It is not necessarily wrong that there
173    /// are duplicates, but the others should probably be removed.
174    WarnFollowing,
175    /// Same as `WarnFollowing`, but only issues warnings for word-style attributes.
176    ///
177    /// This is only for special cases, for example multiple `#[macro_use]` can
178    /// be warned, but multiple `#[macro_use(...)]` should not because the list
179    /// form has different meaning from the word form.
180    WarnFollowingWordOnly,
181    /// Duplicates after the first attribute will be an error.
182    ///
183    /// This should be used where duplicates would be ignored, but carry extra
184    /// meaning that could cause confusion. For example, `#[stable(since="1.0")]
185    /// #[stable(since="2.0")]`, which version should be used for `stable`?
186    ErrorFollowing,
187    /// Duplicates preceding the last instance of the attribute will be an error.
188    ///
189    /// This is the same as `ErrorFollowing`, except the last attribute is the
190    /// one that is "used". This is typically used in cases like codegen
191    /// attributes which usually only honor the last attribute.
192    ErrorPreceding,
193    /// Duplicates after the first attribute will be an unused_attribute warning
194    /// with a note that this will be an error in the future.
195    ///
196    /// This should be used for attributes that should be `ErrorFollowing`, but
197    /// because older versions of rustc silently accepted (and ignored) the
198    /// attributes, this is used to transition.
199    FutureWarnFollowing,
200    /// Duplicates preceding the last instance of the attribute will be a
201    /// warning, with a note that this will be an error in the future.
202    ///
203    /// This is the same as `FutureWarnFollowing`, except the last attribute is
204    /// the one that is "used". Ideally these can eventually migrate to
205    /// `ErrorPreceding`.
206    FutureWarnPreceding,
207}
208
209/// A convenience macro for constructing attribute templates.
210/// E.g., `template!(Word, List: "description")` means that the attribute
211/// supports forms `#[attr]` and `#[attr(description)]`.
212#[macro_export]
213macro_rules! template {
214    (Word) => { $crate::template!(@ true, None, &[], None, None) };
215    (Word, $link: literal) => { $crate::template!(@ true, None, &[], None, Some($link)) };
216    (List: $descr: expr) => { $crate::template!(@ false, Some($descr), &[], None, None) };
217    (List: $descr: expr, $link: literal) => { $crate::template!(@ false, Some($descr), &[], None, Some($link)) };
218    (OneOf: $one_of: expr) => { $crate::template!(@ false, None, $one_of, None, None) };
219    (NameValueStr: [$($descr: literal),* $(,)?]) => { $crate::template!(@ false, None, &[], Some(&[$($descr,)*]), None) };
220    (NameValueStr: [$($descr: literal),* $(,)?], $link: literal) => { $crate::template!(@ false, None, &[], Some(&[$($descr,)*]), Some($link)) };
221    (NameValueStr: $descr: literal) => { $crate::template!(@ false, None, &[], Some(&[$descr]), None) };
222    (NameValueStr: $descr: literal, $link: literal) => { $crate::template!(@ false, None, &[], Some(&[$descr]), Some($link)) };
223    (Word, List: $descr: expr) => { $crate::template!(@ true, Some($descr), &[], None, None) };
224    (Word, List: $descr: expr, $link: literal) => { $crate::template!(@ true, Some($descr), &[], None, Some($link)) };
225    (Word, NameValueStr: $descr: expr) => { $crate::template!(@ true, None, &[], Some(&[$descr]), None) };
226    (Word, NameValueStr: $descr: expr, $link: literal) => { $crate::template!(@ true, None, &[], Some(&[$descr]), Some($link)) };
227    (List: $descr1: expr, NameValueStr: $descr2: expr) => {
228        $crate::template!(@ false, Some($descr1), &[], Some(&[$descr2]), None)
229    };
230    (List: $descr1: expr, NameValueStr: $descr2: expr, $link: literal) => {
231        $crate::template!(@ false, Some($descr1), &[], Some(&[$descr2]), Some($link))
232    };
233    (Word, List: $descr1: expr, NameValueStr: $descr2: expr) => {
234        $crate::template!(@ true, Some($descr1), &[], Some(&[$descr2]), None)
235    };
236    (Word, List: $descr1: expr, NameValueStr: $descr2: expr, $link: literal) => {
237        $crate::template!(@ true, Some($descr1), &[], Some(&[$descr2]), Some($link))
238    };
239    (@ $word: expr, $list: expr, $one_of: expr, $name_value_str: expr, $link: expr) => { $crate::AttributeTemplate {
240        word: $word, list: $list, one_of: $one_of, name_value_str: $name_value_str, docs: $link,
241    } };
242}
243
244macro_rules! ungated {
245    (unsafe($edition:ident) $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
246        BuiltinAttribute {
247            name: sym::$attr,
248            encode_cross_crate: $encode_cross_crate,
249            type_: $typ,
250            safety: AttributeSafety::Unsafe { unsafe_since: Some(Edition::$edition) },
251            template: $tpl,
252            gate: Ungated,
253            duplicates: $duplicates,
254        }
255    };
256    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
257        BuiltinAttribute {
258            name: sym::$attr,
259            encode_cross_crate: $encode_cross_crate,
260            type_: $typ,
261            safety: AttributeSafety::Unsafe { unsafe_since: None },
262            template: $tpl,
263            gate: Ungated,
264            duplicates: $duplicates,
265        }
266    };
267    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
268        BuiltinAttribute {
269            name: sym::$attr,
270            encode_cross_crate: $encode_cross_crate,
271            type_: $typ,
272            safety: AttributeSafety::Normal,
273            template: $tpl,
274            gate: Ungated,
275            duplicates: $duplicates,
276        }
277    };
278}
279
280macro_rules! gated {
281    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $gate:ident, $message:expr $(,)?) => {
282        BuiltinAttribute {
283            name: sym::$attr,
284            encode_cross_crate: $encode_cross_crate,
285            type_: $typ,
286            safety: AttributeSafety::Unsafe { unsafe_since: None },
287            template: $tpl,
288            duplicates: $duplicates,
289            gate: Gated {
290                feature: sym::$gate,
291                message: $message,
292                check: Features::$gate,
293                notes: &[],
294            },
295        }
296    };
297    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $message:expr $(,)?) => {
298        BuiltinAttribute {
299            name: sym::$attr,
300            encode_cross_crate: $encode_cross_crate,
301            type_: $typ,
302            safety: AttributeSafety::Unsafe { unsafe_since: None },
303            template: $tpl,
304            duplicates: $duplicates,
305            gate: Gated {
306                feature: sym::$attr,
307                message: $message,
308                check: Features::$attr,
309                notes: &[],
310            },
311        }
312    };
313    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $gate:ident, $message:expr $(,)?) => {
314        BuiltinAttribute {
315            name: sym::$attr,
316            encode_cross_crate: $encode_cross_crate,
317            type_: $typ,
318            safety: AttributeSafety::Normal,
319            template: $tpl,
320            duplicates: $duplicates,
321            gate: Gated {
322                feature: sym::$gate,
323                message: $message,
324                check: Features::$gate,
325                notes: &[],
326            },
327        }
328    };
329    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $message:expr $(,)?) => {
330        BuiltinAttribute {
331            name: sym::$attr,
332            encode_cross_crate: $encode_cross_crate,
333            type_: $typ,
334            safety: AttributeSafety::Normal,
335            template: $tpl,
336            duplicates: $duplicates,
337            gate: Gated {
338                feature: sym::$attr,
339                message: $message,
340                check: Features::$attr,
341                notes: &[],
342            },
343        }
344    };
345}
346
347macro_rules! rustc_attr {
348    (TEST, $attr:ident, $typ:expr, $tpl:expr, $duplicate:expr, $encode_cross_crate:expr $(,)?) => {
349        rustc_attr!(
350            $attr,
351            $typ,
352            $tpl,
353            $duplicate,
354            $encode_cross_crate,
355            concat!(
356                "the `#[",
357                stringify!($attr),
358                "]` attribute is used for rustc unit tests"
359            ),
360        )
361    };
362    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $($notes:expr),* $(,)?) => {
363        BuiltinAttribute {
364            name: sym::$attr,
365            encode_cross_crate: $encode_cross_crate,
366            type_: $typ,
367            safety: AttributeSafety::Normal,
368            template: $tpl,
369            duplicates: $duplicates,
370            gate: Gated {
371                feature: sym::rustc_attrs,
372                message: "use of an internal attribute",
373                check: Features::rustc_attrs,
374                notes: &[
375                    concat!("the `#[",
376                    stringify!($attr),
377                    "]` attribute is an internal implementation detail that will never be stable"),
378                    $($notes),*
379                    ]
380            },
381        }
382    };
383}
384
385macro_rules! experimental {
386    ($attr:ident) => {
387        concat!("the `#[", stringify!($attr), "]` attribute is an experimental feature")
388    };
389}
390
391pub struct BuiltinAttribute {
392    pub name: Symbol,
393    /// Whether this attribute is encode cross crate.
394    ///
395    /// If so, it is encoded in the crate metadata.
396    /// Otherwise, it can only be used in the local crate.
397    pub encode_cross_crate: EncodeCrossCrate,
398    pub type_: AttributeType,
399    pub safety: AttributeSafety,
400    pub template: AttributeTemplate,
401    pub duplicates: AttributeDuplicates,
402    pub gate: AttributeGate,
403}
404
405/// Attributes that have a special meaning to rustc or rustdoc.
406#[rustfmt::skip]
407pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
408    // ==========================================================================
409    // Stable attributes:
410    // ==========================================================================
411
412    // Conditional compilation:
413    ungated!(
414        cfg, Normal,
415        template!(
416            List: &["predicate"],
417            "https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg-attribute"
418        ),
419        DuplicatesOk, EncodeCrossCrate::Yes
420    ),
421    ungated!(
422        cfg_attr, Normal,
423        template!(
424            List: &["predicate, attr1, attr2, ..."],
425            "https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute"
426        ),
427        DuplicatesOk, EncodeCrossCrate::Yes
428    ),
429
430    // Testing:
431    ungated!(
432        ignore, Normal,
433        template!(
434            Word,
435            NameValueStr: "reason",
436            "https://doc.rust-lang.org/reference/attributes/testing.html#the-ignore-attribute"
437        ),
438        WarnFollowing, EncodeCrossCrate::No,
439    ),
440    ungated!(
441        should_panic, Normal,
442        template!(
443            Word,
444            List: &[r#"expected = "reason""#],
445            NameValueStr: "reason",
446            "https://doc.rust-lang.org/reference/attributes/testing.html#the-should_panic-attribute"
447        ),
448        FutureWarnFollowing, EncodeCrossCrate::No,
449    ),
450    // FIXME(Centril): This can be used on stable but shouldn't.
451    ungated!(
452        reexport_test_harness_main, CrateLevel, template!(NameValueStr: "name"), ErrorFollowing,
453        EncodeCrossCrate::No,
454    ),
455
456    // Macros:
457    ungated!(
458        automatically_derived, Normal,
459        template!(
460            Word,
461            "https://doc.rust-lang.org/reference/attributes/derive.html#the-automatically_derived-attribute"
462        ),
463        WarnFollowing, EncodeCrossCrate::Yes
464    ),
465    ungated!(
466        macro_use, Normal,
467        template!(
468            Word,
469            List: &["name1, name2, ..."],
470            "https://doc.rust-lang.org/reference/macros-by-example.html#the-macro_use-attribute"
471        ),
472        WarnFollowingWordOnly, EncodeCrossCrate::No,
473    ),
474    ungated!(macro_escape, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No), // Deprecated synonym for `macro_use`.
475    ungated!(
476        macro_export, Normal,
477        template!(
478            Word,
479            List: &["local_inner_macros"],
480            "https://doc.rust-lang.org/reference/macros-by-example.html#path-based-scope"
481        ),
482        WarnFollowing, EncodeCrossCrate::Yes
483    ),
484    ungated!(
485        proc_macro, Normal,
486        template!(
487            Word,
488            "https://doc.rust-lang.org/reference/procedural-macros.html#function-like-procedural-macros"),
489        ErrorFollowing, EncodeCrossCrate::No
490    ),
491    ungated!(
492        proc_macro_derive, Normal,
493        template!(
494            List: &["TraitName", "TraitName, attributes(name1, name2, ...)"],
495            "https://doc.rust-lang.org/reference/procedural-macros.html#derive-macros"
496        ),
497        ErrorFollowing, EncodeCrossCrate::No,
498    ),
499    ungated!(
500        proc_macro_attribute, Normal,
501        template!(Word, "https://doc.rust-lang.org/reference/procedural-macros.html#attribute-macros"),
502        ErrorFollowing, EncodeCrossCrate::No
503    ),
504
505    // Lints:
506    ungated!(
507        warn, Normal,
508        template!(
509            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
510            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
511        ),
512        DuplicatesOk, EncodeCrossCrate::No,
513    ),
514    ungated!(
515        allow, Normal,
516        template!(
517            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
518            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
519        ),
520        DuplicatesOk, EncodeCrossCrate::No,
521    ),
522    ungated!(
523        expect, Normal,
524        template!(
525            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
526            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
527        ),
528        DuplicatesOk, EncodeCrossCrate::No,
529    ),
530    ungated!(
531        forbid, Normal,
532        template!(
533            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
534            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
535        ),
536        DuplicatesOk, EncodeCrossCrate::No
537    ),
538    ungated!(
539        deny, Normal,
540        template!(
541            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
542            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
543        ),
544        DuplicatesOk, EncodeCrossCrate::No
545    ),
546    ungated!(
547        must_use, Normal,
548        template!(
549            Word,
550            NameValueStr: "reason",
551            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute"
552        ),
553        FutureWarnFollowing, EncodeCrossCrate::Yes
554    ),
555    gated!(
556        must_not_suspend, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing,
557        EncodeCrossCrate::Yes, experimental!(must_not_suspend)
558    ),
559    ungated!(
560        deprecated, Normal,
561        template!(
562            Word,
563            List: &[r#"/*opt*/ since = "version", /*opt*/ note = "reason""#],
564            NameValueStr: "reason",
565            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute"
566        ),
567        ErrorFollowing, EncodeCrossCrate::Yes
568    ),
569
570    // Crate properties:
571    ungated!(
572        crate_name, CrateLevel,
573        template!(
574            NameValueStr: "name",
575            "https://doc.rust-lang.org/reference/crates-and-source-files.html#the-crate_name-attribute"
576        ),
577        FutureWarnFollowing, EncodeCrossCrate::No,
578    ),
579    ungated!(
580        crate_type, CrateLevel,
581        template!(
582            NameValueStr: ["bin", "lib", "dylib", "cdylib", "rlib", "staticlib", "sdylib", "proc-macro"],
583            "https://doc.rust-lang.org/reference/linkage.html"
584        ),
585        DuplicatesOk, EncodeCrossCrate::No,
586    ),
587
588    // ABI, linking, symbols, and FFI
589    ungated!(
590        link, Normal,
591        template!(List: &[
592            r#"name = "...""#,
593            r#"name = "...", kind = "dylib|static|...""#,
594            r#"name = "...", wasm_import_module = "...""#,
595            r#"name = "...", import_name_type = "decorated|noprefix|undecorated""#,
596            r#"name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated""#,
597        ], "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute"),
598        DuplicatesOk, EncodeCrossCrate::No,
599    ),
600    ungated!(
601        link_name, Normal,
602        template!(NameValueStr: "name", "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_name-attribute"),
603        FutureWarnPreceding, EncodeCrossCrate::Yes
604    ),
605    ungated!(
606        no_link, Normal,
607        template!(Word, "https://doc.rust-lang.org/reference/items/extern-crates.html#the-no_link-attribute"),
608        WarnFollowing, EncodeCrossCrate::No
609    ),
610    ungated!(
611        repr, Normal,
612        template!(
613            List: &["C", "Rust", "transparent", "align(...)", "packed(...)", "<integer type>"],
614            "https://doc.rust-lang.org/reference/type-layout.html#representations"
615        ),
616        DuplicatesOk, EncodeCrossCrate::No
617    ),
618    // FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
619    gated!(rustc_align, Normal, template!(List: &["alignment"]), DuplicatesOk, EncodeCrossCrate::No, fn_align, experimental!(rustc_align)),
620    ungated!(
621        unsafe(Edition2024) export_name, Normal,
622        template!(NameValueStr: "name", "https://doc.rust-lang.org/reference/abi.html#the-export_name-attribute"),
623        FutureWarnPreceding, EncodeCrossCrate::No
624    ),
625    ungated!(
626        unsafe(Edition2024) link_section, Normal,
627        template!(NameValueStr: "name", "https://doc.rust-lang.org/reference/abi.html#the-link_section-attribute"),
628        FutureWarnPreceding, EncodeCrossCrate::No
629    ),
630    ungated!(
631        unsafe(Edition2024) no_mangle, Normal,
632        template!(Word, "https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute"),
633        WarnFollowing, EncodeCrossCrate::No
634    ),
635    ungated!(
636        used, Normal,
637        template!(Word, List: &["compiler", "linker"], "https://doc.rust-lang.org/reference/abi.html#the-used-attribute"),
638        WarnFollowing, EncodeCrossCrate::No
639    ),
640    ungated!(
641        link_ordinal, Normal,
642        template!(List: &["ordinal"], "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_ordinal-attribute"),
643        ErrorPreceding, EncodeCrossCrate::Yes
644    ),
645    ungated!(
646        unsafe naked, Normal,
647        template!(Word, "https://doc.rust-lang.org/reference/attributes/codegen.html#the-naked-attribute"),
648        WarnFollowing, EncodeCrossCrate::No
649    ),
650
651    // Limits:
652    ungated!(
653        recursion_limit, CrateLevel,
654        template!(NameValueStr: "N", "https://doc.rust-lang.org/reference/attributes/limits.html#the-recursion_limit-attribute"),
655        FutureWarnFollowing, EncodeCrossCrate::No
656    ),
657    ungated!(
658        type_length_limit, CrateLevel,
659        template!(NameValueStr: "N", "https://doc.rust-lang.org/reference/attributes/limits.html#the-type_length_limit-attribute"),
660        FutureWarnFollowing, EncodeCrossCrate::No
661    ),
662    gated!(
663        move_size_limit, CrateLevel, template!(NameValueStr: "N"), ErrorFollowing,
664        EncodeCrossCrate::No, large_assignments, experimental!(move_size_limit)
665    ),
666
667    // Entry point:
668    ungated!(
669        no_main, CrateLevel,
670        template!(Word, "https://doc.rust-lang.org/reference/crates-and-source-files.html#the-no_main-attribute"),
671        WarnFollowing, EncodeCrossCrate::No
672    ),
673
674    // Modules, prelude, and resolution:
675    ungated!(
676        path, Normal,
677        template!(NameValueStr: "file", "https://doc.rust-lang.org/reference/items/modules.html#the-path-attribute"),
678        FutureWarnFollowing, EncodeCrossCrate::No
679    ),
680    ungated!(
681        no_std, CrateLevel,
682        template!(Word, "https://doc.rust-lang.org/reference/names/preludes.html#the-no_std-attribute"),
683        WarnFollowing, EncodeCrossCrate::No
684    ),
685    ungated!(
686        no_implicit_prelude, Normal,
687        template!(Word, "https://doc.rust-lang.org/reference/names/preludes.html#the-no_implicit_prelude-attribute"),
688        WarnFollowing, EncodeCrossCrate::No
689    ),
690    ungated!(
691        non_exhaustive, Normal,
692        template!(Word, "https://doc.rust-lang.org/reference/attributes/type_system.html#the-non_exhaustive-attribute"),
693        WarnFollowing, EncodeCrossCrate::Yes
694    ),
695
696    // Runtime
697    ungated!(
698        windows_subsystem, CrateLevel,
699        template!(NameValueStr: ["windows", "console"], "https://doc.rust-lang.org/reference/runtime.html#the-windows_subsystem-attribute"),
700        FutureWarnFollowing, EncodeCrossCrate::No
701    ),
702    ungated!( // RFC 2070
703        panic_handler, Normal,
704        template!(Word, "https://doc.rust-lang.org/reference/panic.html#the-panic_handler-attribute"),
705        WarnFollowing, EncodeCrossCrate::Yes
706    ),
707
708    // Code generation:
709    ungated!(
710        inline, Normal,
711        template!(
712            Word,
713            List: &["always", "never"],
714            "https://doc.rust-lang.org/reference/attributes/codegen.html#the-inline-attribute"
715        ),
716        FutureWarnFollowing, EncodeCrossCrate::No
717    ),
718    ungated!(
719        cold, Normal,
720        template!(Word, "https://doc.rust-lang.org/reference/attributes/codegen.html#the-cold-attribute"),
721        WarnFollowing, EncodeCrossCrate::No
722    ),
723    ungated!(
724        no_builtins, CrateLevel,
725        template!(Word, "https://doc.rust-lang.org/reference/attributes/codegen.html#the-no_builtins-attribute"),
726        WarnFollowing, EncodeCrossCrate::Yes
727    ),
728    ungated!(
729        target_feature, Normal,
730        template!(List: &[r#"enable = "name""#], "https://doc.rust-lang.org/reference/attributes/codegen.html#the-target_feature-attribute"),
731        DuplicatesOk, EncodeCrossCrate::No,
732    ),
733    ungated!(
734        track_caller, Normal,
735        template!(Word, "https://doc.rust-lang.org/reference/attributes/codegen.html#the-track_caller-attribute"),
736        WarnFollowing, EncodeCrossCrate::Yes
737    ),
738    ungated!(
739        instruction_set, Normal,
740        template!(List: &["set"], "https://doc.rust-lang.org/reference/attributes/codegen.html#the-instruction_set-attribute"),
741        ErrorPreceding, EncodeCrossCrate::No
742    ),
743    gated!(
744        no_sanitize, Normal,
745        template!(List: &["address, kcfi, memory, thread"]), DuplicatesOk,
746        EncodeCrossCrate::No, experimental!(no_sanitize)
747    ),
748    gated!(
749        coverage, Normal, template!(OneOf: &[sym::off, sym::on]),
750        ErrorPreceding, EncodeCrossCrate::No,
751        coverage_attribute, experimental!(coverage)
752    ),
753
754    ungated!(
755        doc, Normal,
756        template!(
757            List: &["hidden", "inline"],
758            NameValueStr: "string",
759            "https://doc.rust-lang.org/rustdoc/write-documentation/the-doc-attribute.html"
760        ),
761        DuplicatesOk, EncodeCrossCrate::Yes
762    ),
763
764    // Debugging
765    ungated!(
766        debugger_visualizer, Normal,
767        template!(
768            List: &[r#"natvis_file = "...", gdb_script_file = "...""#],
769            "https://doc.rust-lang.org/reference/attributes/debugger.html#the-debugger_visualizer-attribute"
770        ),
771        DuplicatesOk, EncodeCrossCrate::No
772    ),
773    ungated!(
774        collapse_debuginfo, Normal,
775        template!(
776            List: &["no", "external", "yes"],
777            "https://doc.rust-lang.org/reference/attributes/debugger.html#the-collapse_debuginfo-attribute"
778        ),
779        ErrorFollowing, EncodeCrossCrate::Yes
780    ),
781
782    // ==========================================================================
783    // Unstable attributes:
784    // ==========================================================================
785
786    // Linking:
787    gated!(
788        export_stable, Normal, template!(Word), WarnFollowing,
789        EncodeCrossCrate::No, experimental!(export_stable)
790    ),
791
792    // Testing:
793    gated!(
794        test_runner, CrateLevel, template!(List: &["path"]), ErrorFollowing,
795        EncodeCrossCrate::Yes, custom_test_frameworks,
796        "custom test frameworks are an unstable feature",
797    ),
798    // RFC #1268
799    gated!(
800        marker, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
801        marker_trait_attr, experimental!(marker)
802    ),
803    gated!(
804        thread_local, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
805        "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
806    ),
807    gated!(
808        no_core, CrateLevel, template!(Word), WarnFollowing,
809        EncodeCrossCrate::No, experimental!(no_core)
810    ),
811    // RFC 2412
812    gated!(
813        optimize, Normal, template!(List: &["none", "size", "speed"]), ErrorPreceding,
814        EncodeCrossCrate::No, optimize_attribute, experimental!(optimize)
815    ),
816
817    gated!(
818        unsafe ffi_pure, Normal, template!(Word), WarnFollowing,
819        EncodeCrossCrate::No, experimental!(ffi_pure)
820    ),
821    gated!(
822        unsafe ffi_const, Normal, template!(Word), WarnFollowing,
823        EncodeCrossCrate::No, experimental!(ffi_const)
824    ),
825    gated!(
826        register_tool, CrateLevel, template!(List: &["tool1, tool2, ..."]), DuplicatesOk,
827        EncodeCrossCrate::No, experimental!(register_tool),
828    ),
829
830    // RFC 2632
831    // FIXME(const_trait_impl) remove this
832    gated!(
833        const_trait, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No, const_trait_impl,
834        "`const_trait` is a temporary placeholder for marking a trait that is suitable for `const` \
835        `impls` and all default bodies as `const`, which may be removed or renamed in the \
836        future."
837    ),
838    // lang-team MCP 147
839    gated!(
840        deprecated_safe, Normal, template!(List: &[r#"since = "version", note = "...""#]), ErrorFollowing,
841        EncodeCrossCrate::Yes, experimental!(deprecated_safe),
842    ),
843
844    // `#[cfi_encoding = ""]`
845    gated!(
846        cfi_encoding, Normal, template!(NameValueStr: "encoding"), ErrorPreceding,
847        EncodeCrossCrate::Yes, experimental!(cfi_encoding)
848    ),
849
850    // `#[coroutine]` attribute to be applied to closures to make them coroutines instead
851    gated!(
852        coroutine, Normal, template!(Word), ErrorFollowing,
853        EncodeCrossCrate::No, coroutines, experimental!(coroutine)
854    ),
855
856    // RFC 3543
857    // `#[patchable_function_entry(prefix_nops = m, entry_nops = n)]`
858    gated!(
859        patchable_function_entry, Normal, template!(List: &["prefix_nops = m, entry_nops = n"]), ErrorPreceding,
860        EncodeCrossCrate::Yes, experimental!(patchable_function_entry)
861    ),
862
863    // Probably temporary component of min_generic_const_args.
864    // `#[type_const] const ASSOC: usize;`
865    gated!(
866        type_const, Normal, template!(Word), ErrorFollowing,
867        EncodeCrossCrate::Yes, min_generic_const_args, experimental!(type_const),
868    ),
869
870    // The `#[loop_match]` and `#[const_continue]` attributes are part of the
871    // lang experiment for RFC 3720 tracked in:
872    //
873    // - https://github.com/rust-lang/rust/issues/132306
874    gated!(
875        const_continue, Normal, template!(Word), ErrorFollowing,
876        EncodeCrossCrate::No, loop_match, experimental!(const_continue)
877    ),
878    gated!(
879        loop_match, Normal, template!(Word), ErrorFollowing,
880        EncodeCrossCrate::No, loop_match, experimental!(loop_match)
881    ),
882
883    // ==========================================================================
884    // Internal attributes: Stability, deprecation, and unsafe:
885    // ==========================================================================
886
887    ungated!(
888        feature, CrateLevel,
889        template!(List: &["name1, name2, ..."]), DuplicatesOk, EncodeCrossCrate::No,
890    ),
891    // DuplicatesOk since it has its own validation
892    ungated!(
893        stable, Normal,
894        template!(List: &[r#"feature = "name", since = "version""#]), DuplicatesOk, EncodeCrossCrate::No,
895    ),
896    ungated!(
897        unstable, Normal,
898        template!(List: &[r#"feature = "name", reason = "...", issue = "N""#]), DuplicatesOk,
899        EncodeCrossCrate::Yes
900    ),
901    ungated!(
902        unstable_feature_bound, Normal, template!(Word, List: &["feat1, feat2, ..."]),
903        DuplicatesOk, EncodeCrossCrate::No,
904    ),
905    ungated!(
906        rustc_const_unstable, Normal, template!(List: &[r#"feature = "name""#]),
907        DuplicatesOk, EncodeCrossCrate::Yes
908    ),
909    ungated!(
910        rustc_const_stable, Normal,
911        template!(List: &[r#"feature = "name""#]), DuplicatesOk, EncodeCrossCrate::No,
912    ),
913    ungated!(
914        rustc_default_body_unstable, Normal,
915        template!(List: &[r#"feature = "name", reason = "...", issue = "N""#]),
916        DuplicatesOk, EncodeCrossCrate::No
917    ),
918    gated!(
919        allow_internal_unstable, Normal, template!(Word, List: &["feat1, feat2, ..."]),
920        DuplicatesOk, EncodeCrossCrate::Yes,
921        "allow_internal_unstable side-steps feature gating and stability checks",
922    ),
923    gated!(
924        allow_internal_unsafe, Normal, template!(Word), WarnFollowing,
925        EncodeCrossCrate::No, "allow_internal_unsafe side-steps the unsafe_code lint",
926    ),
927    rustc_attr!(
928        rustc_allowed_through_unstable_modules, Normal, template!(NameValueStr: "deprecation message"),
929        WarnFollowing, EncodeCrossCrate::No,
930        "rustc_allowed_through_unstable_modules special cases accidental stabilizations of stable items \
931        through unstable paths"
932    ),
933    rustc_attr!(
934        rustc_deprecated_safe_2024, Normal, template!(List: &[r#"audit_that = "...""#]),
935        ErrorFollowing, EncodeCrossCrate::Yes,
936        "`#[rustc_deprecated_safe_2024]` is used to declare functions unsafe across the edition 2024 boundary",
937    ),
938    rustc_attr!(
939        rustc_pub_transparent, Normal, template!(Word),
940        ErrorFollowing, EncodeCrossCrate::Yes,
941        "used internally to mark types with a `transparent` representation when it is guaranteed by the documentation",
942    ),
943
944
945    // ==========================================================================
946    // Internal attributes: Type system related:
947    // ==========================================================================
948
949    gated!(fundamental, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes, experimental!(fundamental)),
950    gated!(
951        may_dangle, Normal, template!(Word), WarnFollowing,
952        EncodeCrossCrate::No, dropck_eyepatch,
953        "`may_dangle` has unstable semantics and may be removed in the future",
954    ),
955
956    rustc_attr!(
957        rustc_never_type_options,
958        Normal,
959        template!(List: &[
960            "",
961            r#"fallback = "unit""#,
962            r#"fallback = "niko""#,
963            r#"fallback = "never""#,
964            r#"fallback = "no""#,
965        ]),
966        ErrorFollowing,
967        EncodeCrossCrate::No,
968        "`rustc_never_type_options` is used to experiment with never type fallback and work on \
969         never type stabilization"
970    ),
971
972    // ==========================================================================
973    // Internal attributes: Runtime related:
974    // ==========================================================================
975
976    rustc_attr!(
977        rustc_allocator, Normal, template!(Word), WarnFollowing,
978        EncodeCrossCrate::No,
979    ),
980    rustc_attr!(
981        rustc_nounwind, Normal, template!(Word), WarnFollowing,
982        EncodeCrossCrate::No,
983    ),
984    rustc_attr!(
985        rustc_reallocator, Normal, template!(Word), WarnFollowing,
986        EncodeCrossCrate::No,
987    ),
988    rustc_attr!(
989        rustc_deallocator, Normal, template!(Word), WarnFollowing,
990        EncodeCrossCrate::No,
991    ),
992    rustc_attr!(
993        rustc_allocator_zeroed, Normal, template!(Word), WarnFollowing,
994        EncodeCrossCrate::No,
995    ),
996    gated!(
997        default_lib_allocator, Normal, template!(Word), WarnFollowing,
998        EncodeCrossCrate::No, allocator_internals, experimental!(default_lib_allocator),
999    ),
1000    gated!(
1001        needs_allocator, Normal, template!(Word), WarnFollowing,
1002        EncodeCrossCrate::No, allocator_internals, experimental!(needs_allocator),
1003    ),
1004    gated!(
1005        panic_runtime, CrateLevel, template!(Word), WarnFollowing,
1006        EncodeCrossCrate::No, experimental!(panic_runtime)
1007    ),
1008    gated!(
1009        needs_panic_runtime, CrateLevel, template!(Word), WarnFollowing,
1010        EncodeCrossCrate::No, experimental!(needs_panic_runtime)
1011    ),
1012    gated!(
1013        compiler_builtins, CrateLevel, template!(Word), WarnFollowing,
1014        EncodeCrossCrate::No,
1015        "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \
1016        which contains compiler-rt intrinsics and will never be stable",
1017    ),
1018    gated!(
1019        profiler_runtime, CrateLevel, template!(Word), WarnFollowing,
1020        EncodeCrossCrate::No,
1021        "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \
1022        which contains the profiler runtime and will never be stable",
1023    ),
1024
1025    // ==========================================================================
1026    // Internal attributes, Linkage:
1027    // ==========================================================================
1028
1029    gated!(
1030        linkage, Normal, template!(NameValueStr: [
1031            "available_externally",
1032            "common",
1033            "extern_weak",
1034            "external",
1035            "internal",
1036            "linkonce",
1037            "linkonce_odr",
1038            "weak",
1039            "weak_odr",
1040        ], "https://doc.rust-lang.org/reference/linkage.html"),
1041        ErrorPreceding, EncodeCrossCrate::No,
1042        "the `linkage` attribute is experimental and not portable across platforms",
1043    ),
1044    rustc_attr!(
1045        rustc_std_internal_symbol, Normal, template!(Word), WarnFollowing,
1046        EncodeCrossCrate::No,
1047    ),
1048
1049    // ==========================================================================
1050    // Internal attributes, Macro related:
1051    // ==========================================================================
1052
1053    rustc_attr!(
1054        rustc_builtin_macro, Normal,
1055        template!(Word, List: &["name", "name, /*opt*/ attributes(name1, name2, ...)"]), ErrorFollowing,
1056        EncodeCrossCrate::Yes,
1057    ),
1058    rustc_attr!(
1059        rustc_proc_macro_decls, Normal, template!(Word), WarnFollowing,
1060        EncodeCrossCrate::No,
1061    ),
1062    rustc_attr!(
1063        rustc_macro_transparency, Normal,
1064        template!(NameValueStr: ["transparent", "semiopaque", "opaque"]), ErrorFollowing,
1065        EncodeCrossCrate::Yes, "used internally for testing macro hygiene",
1066    ),
1067    rustc_attr!(
1068        rustc_autodiff, Normal,
1069        template!(Word, List: &[r#""...""#]), DuplicatesOk,
1070        EncodeCrossCrate::Yes,
1071    ),
1072    // Traces that are left when `cfg` and `cfg_attr` attributes are expanded.
1073    // The attributes are not gated, to avoid stability errors, but they cannot be used in stable
1074    // or unstable code directly because `sym::cfg_(attr_)trace` are not valid identifiers, they
1075    // can only be generated by the compiler.
1076    ungated!(
1077        cfg_trace, Normal, template!(Word /* irrelevant */), DuplicatesOk,
1078        EncodeCrossCrate::No
1079    ),
1080    ungated!(
1081        cfg_attr_trace, Normal, template!(Word /* irrelevant */), DuplicatesOk,
1082        EncodeCrossCrate::No
1083    ),
1084
1085    // ==========================================================================
1086    // Internal attributes, Diagnostics related:
1087    // ==========================================================================
1088
1089    rustc_attr!(
1090        rustc_on_unimplemented, Normal,
1091        template!(
1092            List: &[r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#],
1093            NameValueStr: "message"
1094        ),
1095        ErrorFollowing, EncodeCrossCrate::Yes,
1096        "see `#[diagnostic::on_unimplemented]` for the stable equivalent of this attribute"
1097    ),
1098    rustc_attr!(
1099        rustc_confusables, Normal,
1100        template!(List: &[r#""name1", "name2", ..."#]),
1101        ErrorFollowing, EncodeCrossCrate::Yes,
1102    ),
1103    // Enumerates "identity-like" conversion methods to suggest on type mismatch.
1104    rustc_attr!(
1105        rustc_conversion_suggestion, Normal, template!(Word),
1106        WarnFollowing, EncodeCrossCrate::Yes,
1107    ),
1108    // Prevents field reads in the marked trait or method to be considered
1109    // during dead code analysis.
1110    rustc_attr!(
1111        rustc_trivial_field_reads, Normal, template!(Word),
1112        WarnFollowing, EncodeCrossCrate::Yes,
1113    ),
1114    // Used by the `rustc::potential_query_instability` lint to warn methods which
1115    // might not be stable during incremental compilation.
1116    rustc_attr!(
1117        rustc_lint_query_instability, Normal, template!(Word),
1118        WarnFollowing, EncodeCrossCrate::Yes,
1119    ),
1120    // Used by the `rustc::untracked_query_information` lint to warn methods which
1121    // might not be stable during incremental compilation.
1122    rustc_attr!(
1123        rustc_lint_untracked_query_information, Normal, template!(Word),
1124        WarnFollowing, EncodeCrossCrate::Yes,
1125    ),
1126    // Used by the `rustc::diagnostic_outside_of_impl` lints to assist in changes to diagnostic
1127    // APIs. Any function with this attribute will be checked by that lint.
1128    rustc_attr!(
1129        rustc_lint_diagnostics, Normal, template!(Word),
1130        WarnFollowing, EncodeCrossCrate::Yes,
1131    ),
1132    // Used by the `rustc::bad_opt_access` lint to identify `DebuggingOptions` and `CodegenOptions`
1133    // types (as well as any others in future).
1134    rustc_attr!(
1135        rustc_lint_opt_ty, Normal, template!(Word),
1136        WarnFollowing, EncodeCrossCrate::Yes,
1137    ),
1138    // Used by the `rustc::bad_opt_access` lint on fields
1139    // types (as well as any others in future).
1140    rustc_attr!(
1141        rustc_lint_opt_deny_field_access, Normal, template!(List: &["message"]),
1142        WarnFollowing, EncodeCrossCrate::Yes,
1143    ),
1144
1145    // ==========================================================================
1146    // Internal attributes, Const related:
1147    // ==========================================================================
1148
1149    rustc_attr!(
1150        rustc_promotable, Normal, template!(Word), WarnFollowing,
1151        EncodeCrossCrate::No, ),
1152    rustc_attr!(
1153        rustc_legacy_const_generics, Normal, template!(List: &["N"]), ErrorFollowing,
1154        EncodeCrossCrate::Yes,
1155    ),
1156    // Do not const-check this function's body. It will always get replaced during CTFE via `hook_special_const_fn`.
1157    rustc_attr!(
1158        rustc_do_not_const_check, Normal, template!(Word), WarnFollowing,
1159        EncodeCrossCrate::Yes, "`#[rustc_do_not_const_check]` skips const-check for this function's body",
1160    ),
1161    rustc_attr!(
1162        rustc_const_panic_str, Normal, template!(Word), WarnFollowing,
1163        EncodeCrossCrate::Yes, "`#[rustc_const_panic_str]` ensures the argument to this function is &&str during const-check",
1164    ),
1165    rustc_attr!(
1166        rustc_const_stable_indirect, Normal,
1167        template!(Word),
1168        WarnFollowing,
1169        EncodeCrossCrate::No,
1170        "this is an internal implementation detail",
1171    ),
1172    rustc_attr!(
1173        rustc_intrinsic_const_stable_indirect, Normal,
1174        template!(Word), WarnFollowing, EncodeCrossCrate::No,  "this is an internal implementation detail",
1175    ),
1176    gated!(
1177        rustc_allow_const_fn_unstable, Normal,
1178        template!(Word, List: &["feat1, feat2, ..."]), DuplicatesOk, EncodeCrossCrate::No,
1179        "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
1180    ),
1181
1182    // ==========================================================================
1183    // Internal attributes, Layout related:
1184    // ==========================================================================
1185
1186    rustc_attr!(
1187        rustc_layout_scalar_valid_range_start, Normal, template!(List: &["value"]), ErrorFollowing,
1188        EncodeCrossCrate::Yes,
1189        "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
1190        niche optimizations in the standard library",
1191    ),
1192    rustc_attr!(
1193        rustc_layout_scalar_valid_range_end, Normal, template!(List: &["value"]), ErrorFollowing,
1194        EncodeCrossCrate::Yes,
1195        "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
1196        niche optimizations in the standard library",
1197    ),
1198    rustc_attr!(
1199        rustc_nonnull_optimization_guaranteed, Normal, template!(Word), WarnFollowing,
1200        EncodeCrossCrate::Yes,
1201        "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document \
1202        guaranteed niche optimizations in the standard library",
1203        "the compiler does not even check whether the type indeed is being non-null-optimized; \
1204        it is your responsibility to ensure that the attribute is only used on types that are optimized",
1205    ),
1206
1207    // ==========================================================================
1208    // Internal attributes, Misc:
1209    // ==========================================================================
1210    gated!(
1211        lang, Normal, template!(NameValueStr: "name"), DuplicatesOk, EncodeCrossCrate::No, lang_items,
1212        "lang items are subject to change",
1213    ),
1214    rustc_attr!(
1215        rustc_as_ptr, Normal, template!(Word), ErrorFollowing,
1216        EncodeCrossCrate::Yes,
1217        "`#[rustc_as_ptr]` is used to mark functions returning pointers to their inner allocations."
1218    ),
1219    rustc_attr!(
1220        rustc_pass_by_value, Normal, template!(Word), ErrorFollowing,
1221        EncodeCrossCrate::Yes,
1222        "`#[rustc_pass_by_value]` is used to mark types that must be passed by value instead of reference."
1223    ),
1224    rustc_attr!(
1225        rustc_never_returns_null_ptr, Normal, template!(Word), ErrorFollowing,
1226        EncodeCrossCrate::Yes,
1227        "`#[rustc_never_returns_null_ptr]` is used to mark functions returning non-null pointers."
1228    ),
1229    rustc_attr!(
1230        rustc_no_implicit_autorefs, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes,
1231        "`#[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."
1232    ),
1233    rustc_attr!(
1234        rustc_coherence_is_core, AttributeType::CrateLevel, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1235        "`#![rustc_coherence_is_core]` allows inherent methods on builtin types, only intended to be used in `core`."
1236    ),
1237    rustc_attr!(
1238        rustc_coinductive, AttributeType::Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1239        "`#[rustc_coinductive]` changes a trait to be coinductive, allowing cycles in the trait solver."
1240    ),
1241    rustc_attr!(
1242        rustc_allow_incoherent_impl, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1243        "`#[rustc_allow_incoherent_impl]` has to be added to all impl items of an incoherent inherent impl."
1244    ),
1245    rustc_attr!(
1246        rustc_preserve_ub_checks, AttributeType::CrateLevel, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1247        "`#![rustc_preserve_ub_checks]` prevents the designated crate from evaluating whether UB checks are enabled when optimizing MIR",
1248    ),
1249    rustc_attr!(
1250        rustc_deny_explicit_impl,
1251        AttributeType::Normal,
1252        template!(Word),
1253        ErrorFollowing,
1254        EncodeCrossCrate::No,
1255        "`#[rustc_deny_explicit_impl]` enforces that a trait can have no user-provided impls"
1256    ),
1257    rustc_attr!(
1258        rustc_do_not_implement_via_object,
1259        AttributeType::Normal,
1260        template!(Word),
1261        ErrorFollowing,
1262        EncodeCrossCrate::No,
1263        "`#[rustc_do_not_implement_via_object]` opts out of the automatic trait impl for trait objects \
1264        (`impl Trait for dyn Trait`)"
1265    ),
1266    rustc_attr!(
1267        rustc_has_incoherent_inherent_impls, AttributeType::Normal, template!(Word),
1268        ErrorFollowing, EncodeCrossCrate::Yes,
1269        "`#[rustc_has_incoherent_inherent_impls]` allows the addition of incoherent inherent impls for \
1270         the given type by annotating all impl items with `#[rustc_allow_incoherent_impl]`."
1271    ),
1272
1273    BuiltinAttribute {
1274        name: sym::rustc_diagnostic_item,
1275        // FIXME: This can be `true` once we always use `tcx.is_diagnostic_item`.
1276        encode_cross_crate: EncodeCrossCrate::Yes,
1277        type_: Normal,
1278        safety: AttributeSafety::Normal,
1279        template: template!(NameValueStr: "name"),
1280        duplicates: ErrorFollowing,
1281        gate: Gated{
1282            feature: sym::rustc_attrs,
1283            message: "use of an internal attribute",
1284            check: Features::rustc_attrs,
1285            notes: &["the `#[rustc_diagnostic_item]` attribute allows the compiler to reference types \
1286            from the standard library for diagnostic purposes"],
1287        },
1288    },
1289    gated!(
1290        // Used in resolve:
1291        prelude_import, Normal, template!(Word), WarnFollowing,
1292        EncodeCrossCrate::No, "`#[prelude_import]` is for use by rustc only",
1293    ),
1294    gated!(
1295        rustc_paren_sugar, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1296        unboxed_closures, "unboxed_closures are still evolving",
1297    ),
1298    rustc_attr!(
1299        rustc_inherit_overflow_checks, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1300        "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \
1301        overflow checking behavior of several functions in the standard library that are inlined \
1302        across crates",
1303    ),
1304    rustc_attr!(
1305        rustc_reservation_impl, Normal,
1306        template!(NameValueStr: "reservation message"), ErrorFollowing, EncodeCrossCrate::Yes,
1307        "the `#[rustc_reservation_impl]` attribute is internally used \
1308        for reserving `impl<T> From<!> for T` as part of the effort to stabilize `!`"
1309    ),
1310    rustc_attr!(
1311        rustc_test_marker, Normal, template!(NameValueStr: "name"), WarnFollowing,
1312        EncodeCrossCrate::No, "the `#[rustc_test_marker]` attribute is used internally to track tests",
1313    ),
1314    rustc_attr!(
1315        rustc_unsafe_specialization_marker, Normal, template!(Word),
1316        WarnFollowing, EncodeCrossCrate::No,
1317        "the `#[rustc_unsafe_specialization_marker]` attribute is used to check specializations"
1318    ),
1319    rustc_attr!(
1320        rustc_specialization_trait, Normal, template!(Word),
1321        WarnFollowing, EncodeCrossCrate::No,
1322        "the `#[rustc_specialization_trait]` attribute is used to check specializations"
1323    ),
1324    rustc_attr!(
1325        rustc_main, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1326        "the `#[rustc_main]` attribute is used internally to specify test entry point function",
1327    ),
1328    rustc_attr!(
1329        rustc_skip_during_method_dispatch, Normal, template!(List: &["array, boxed_slice"]), ErrorFollowing,
1330        EncodeCrossCrate::No,
1331        "the `#[rustc_skip_during_method_dispatch]` attribute is used to exclude a trait \
1332        from method dispatch when the receiver is of the following type, for compatibility in \
1333        editions < 2021 (array) or editions < 2024 (boxed_slice)."
1334    ),
1335    rustc_attr!(
1336        rustc_must_implement_one_of, Normal, template!(List: &["function1, function2, ..."]),
1337        ErrorFollowing, EncodeCrossCrate::No,
1338        "the `#[rustc_must_implement_one_of]` attribute is used to change minimal complete \
1339        definition of a trait. Its syntax and semantics are highly experimental and will be \
1340        subject to change before stabilization",
1341    ),
1342    rustc_attr!(
1343        rustc_doc_primitive, Normal, template!(NameValueStr: "primitive name"), ErrorFollowing,
1344        EncodeCrossCrate::Yes, "the `#[rustc_doc_primitive]` attribute is used by the standard library \
1345        to provide a way to generate documentation for primitive types",
1346    ),
1347    gated!(
1348        rustc_intrinsic, Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes, intrinsics,
1349        "the `#[rustc_intrinsic]` attribute is used to declare intrinsics as function items",
1350    ),
1351    rustc_attr!(
1352        rustc_no_mir_inline, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes,
1353        "`#[rustc_no_mir_inline]` prevents the MIR inliner from inlining a function while not affecting codegen"
1354    ),
1355    rustc_attr!(
1356        rustc_force_inline, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing, EncodeCrossCrate::Yes,
1357        "`#[rustc_force_inline]` forces a free function to be inlined"
1358    ),
1359
1360    // ==========================================================================
1361    // Internal attributes, Testing:
1362    // ==========================================================================
1363
1364    rustc_attr!(TEST, rustc_effective_visibility, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes),
1365    rustc_attr!(
1366        TEST, rustc_outlives, Normal, template!(Word),
1367        WarnFollowing, EncodeCrossCrate::No
1368    ),
1369    rustc_attr!(
1370        TEST, rustc_capture_analysis, Normal, template!(Word),
1371        WarnFollowing, EncodeCrossCrate::No
1372    ),
1373    rustc_attr!(
1374        TEST, rustc_insignificant_dtor, Normal, template!(Word),
1375        WarnFollowing, EncodeCrossCrate::Yes
1376    ),
1377    rustc_attr!(
1378        TEST, rustc_no_implicit_bounds, CrateLevel, template!(Word),
1379        WarnFollowing, EncodeCrossCrate::No
1380    ),
1381    rustc_attr!(
1382        TEST, rustc_strict_coherence, Normal, template!(Word),
1383        WarnFollowing, EncodeCrossCrate::Yes
1384    ),
1385    rustc_attr!(
1386        TEST, rustc_variance, Normal, template!(Word),
1387        WarnFollowing, EncodeCrossCrate::No
1388    ),
1389    rustc_attr!(
1390        TEST, rustc_variance_of_opaques, Normal, template!(Word),
1391        WarnFollowing, EncodeCrossCrate::No
1392    ),
1393    rustc_attr!(
1394        TEST, rustc_hidden_type_of_opaques, Normal, template!(Word),
1395        WarnFollowing, EncodeCrossCrate::No
1396    ),
1397    rustc_attr!(
1398        TEST, rustc_layout, Normal, template!(List: &["field1, field2, ..."]),
1399        WarnFollowing, EncodeCrossCrate::Yes
1400    ),
1401    rustc_attr!(
1402        TEST, rustc_abi, Normal, template!(List: &["field1, field2, ..."]),
1403        WarnFollowing, EncodeCrossCrate::No
1404    ),
1405    rustc_attr!(
1406        TEST, rustc_regions, Normal, template!(Word),
1407        WarnFollowing, EncodeCrossCrate::No
1408    ),
1409    rustc_attr!(
1410        TEST, rustc_delayed_bug_from_inside_query, Normal,
1411        template!(Word),
1412        WarnFollowing, EncodeCrossCrate::No
1413    ),
1414    rustc_attr!(
1415        TEST, rustc_dump_user_args, Normal, template!(Word),
1416        WarnFollowing, EncodeCrossCrate::No
1417    ),
1418    rustc_attr!(
1419        TEST, rustc_evaluate_where_clauses, Normal, template!(Word), WarnFollowing,
1420        EncodeCrossCrate::Yes
1421    ),
1422    rustc_attr!(
1423        TEST, rustc_if_this_changed, Normal, template!(Word, List: &["DepNode"]), DuplicatesOk,
1424        EncodeCrossCrate::No
1425    ),
1426    rustc_attr!(
1427        TEST, rustc_then_this_would_need, Normal, template!(List: &["DepNode"]), DuplicatesOk,
1428        EncodeCrossCrate::No
1429    ),
1430    rustc_attr!(
1431        TEST, rustc_clean, Normal,
1432        template!(List: &[r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#]),
1433        DuplicatesOk, EncodeCrossCrate::No
1434    ),
1435    rustc_attr!(
1436        TEST, rustc_partition_reused, Normal,
1437        template!(List: &[r#"cfg = "...", module = "...""#]), DuplicatesOk, EncodeCrossCrate::No
1438    ),
1439    rustc_attr!(
1440        TEST, rustc_partition_codegened, Normal,
1441        template!(List: &[r#"cfg = "...", module = "...""#]), DuplicatesOk, EncodeCrossCrate::No
1442    ),
1443    rustc_attr!(
1444        TEST, rustc_expected_cgu_reuse, Normal,
1445        template!(List: &[r#"cfg = "...", module = "...", kind = "...""#]), DuplicatesOk,
1446        EncodeCrossCrate::No
1447    ),
1448    rustc_attr!(
1449        TEST, rustc_symbol_name, Normal, template!(Word),
1450        WarnFollowing, EncodeCrossCrate::No
1451    ),
1452    rustc_attr!(
1453        TEST, rustc_def_path, Normal, template!(Word),
1454        WarnFollowing, EncodeCrossCrate::No
1455    ),
1456    rustc_attr!(
1457        TEST, rustc_mir, Normal, template!(List: &["arg1, arg2, ..."]),
1458        DuplicatesOk, EncodeCrossCrate::Yes
1459    ),
1460    gated!(
1461        custom_mir, Normal, template!(List: &[r#"dialect = "...", phase = "...""#]),
1462        ErrorFollowing, EncodeCrossCrate::No,
1463        "the `#[custom_mir]` attribute is just used for the Rust test suite",
1464    ),
1465    rustc_attr!(
1466        TEST, rustc_dump_item_bounds, Normal, template!(Word),
1467        WarnFollowing, EncodeCrossCrate::No
1468    ),
1469    rustc_attr!(
1470        TEST, rustc_dump_predicates, Normal, template!(Word),
1471        WarnFollowing, EncodeCrossCrate::No
1472    ),
1473    rustc_attr!(
1474        TEST, rustc_dump_def_parents, Normal, template!(Word),
1475        WarnFollowing, EncodeCrossCrate::No
1476    ),
1477    rustc_attr!(
1478        TEST, rustc_object_lifetime_default, Normal, template!(Word),
1479        WarnFollowing, EncodeCrossCrate::No
1480    ),
1481    rustc_attr!(
1482        TEST, rustc_dump_vtable, Normal, template!(Word),
1483        WarnFollowing, EncodeCrossCrate::No
1484    ),
1485    rustc_attr!(
1486        TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/),
1487        DuplicatesOk, EncodeCrossCrate::No
1488    ),
1489    rustc_attr!(
1490        TEST, pattern_complexity_limit, CrateLevel, template!(NameValueStr: "N"),
1491        ErrorFollowing, EncodeCrossCrate::No,
1492    ),
1493];
1494
1495pub fn is_builtin_attr_name(name: Symbol) -> bool {
1496    BUILTIN_ATTRIBUTE_MAP.get(&name).is_some()
1497}
1498
1499/// Whether this builtin attribute is encoded cross crate.
1500/// This means it can be used cross crate.
1501pub fn encode_cross_crate(name: Symbol) -> bool {
1502    if let Some(attr) = BUILTIN_ATTRIBUTE_MAP.get(&name) {
1503        attr.encode_cross_crate == EncodeCrossCrate::Yes
1504    } else {
1505        true
1506    }
1507}
1508
1509pub fn is_valid_for_get_attr(name: Symbol) -> bool {
1510    BUILTIN_ATTRIBUTE_MAP.get(&name).is_some_and(|attr| match attr.duplicates {
1511        WarnFollowing | ErrorFollowing | ErrorPreceding | FutureWarnFollowing
1512        | FutureWarnPreceding => true,
1513        DuplicatesOk | WarnFollowingWordOnly => false,
1514    })
1515}
1516
1517pub static BUILTIN_ATTRIBUTE_MAP: LazyLock<FxHashMap<Symbol, &BuiltinAttribute>> =
1518    LazyLock::new(|| {
1519        let mut map = FxHashMap::default();
1520        for attr in BUILTIN_ATTRIBUTES.iter() {
1521            if map.insert(attr.name, attr).is_some() {
1522                panic!("duplicate builtin attribute `{}`", attr.name);
1523            }
1524        }
1525        map
1526    });
1527
1528pub fn is_stable_diagnostic_attribute(sym: Symbol, _features: &Features) -> bool {
1529    match sym {
1530        sym::on_unimplemented | sym::do_not_recommend => true,
1531        _ => false,
1532    }
1533}
rustc_feature/builtin_attrs.rs

rustc_feature/
builtin_attrs.rs
