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::AttrStyle;
10use rustc_hir::attrs::EncodeCrossCrate;
11use rustc_span::edition::Edition;
12use rustc_span::{Symbol, sym};
13
14use crate::Features;
15
16type GateFn = fn(&Features) -> bool;
17
18pub type GatedCfg = (Symbol, Symbol, GateFn);
19
20/// `cfg(...)`'s that are feature gated.
21const GATED_CFGS: &[GatedCfg] = &[
22    // (name in cfg, feature, function to check if the feature is enabled)
23    (sym::overflow_checks, sym::cfg_overflow_checks, Features::cfg_overflow_checks),
24    (sym::ub_checks, sym::cfg_ub_checks, Features::cfg_ub_checks),
25    (sym::contract_checks, sym::cfg_contract_checks, Features::cfg_contract_checks),
26    (sym::target_thread_local, sym::cfg_target_thread_local, Features::cfg_target_thread_local),
27    (
28        sym::target_has_atomic_equal_alignment,
29        sym::cfg_target_has_atomic_equal_alignment,
30        Features::cfg_target_has_atomic_equal_alignment,
31    ),
32    (
33        sym::target_has_atomic_load_store,
34        sym::cfg_target_has_atomic,
35        Features::cfg_target_has_atomic,
36    ),
37    (sym::sanitize, sym::cfg_sanitize, Features::cfg_sanitize),
38    (sym::version, sym::cfg_version, Features::cfg_version),
39    (sym::relocation_model, sym::cfg_relocation_model, Features::cfg_relocation_model),
40    (sym::sanitizer_cfi_generalize_pointers, sym::cfg_sanitizer_cfi, Features::cfg_sanitizer_cfi),
41    (sym::sanitizer_cfi_normalize_integers, sym::cfg_sanitizer_cfi, Features::cfg_sanitizer_cfi),
42    // this is consistent with naming of the compiler flag it's for
43    (sym::fmt_debug, sym::fmt_debug, Features::fmt_debug),
44    (sym::emscripten_wasm_eh, sym::cfg_emscripten_wasm_eh, Features::cfg_emscripten_wasm_eh),
45    (
46        sym::target_has_reliable_f16,
47        sym::cfg_target_has_reliable_f16_f128,
48        Features::cfg_target_has_reliable_f16_f128,
49    ),
50    (
51        sym::target_has_reliable_f16_math,
52        sym::cfg_target_has_reliable_f16_f128,
53        Features::cfg_target_has_reliable_f16_f128,
54    ),
55    (
56        sym::target_has_reliable_f128,
57        sym::cfg_target_has_reliable_f16_f128,
58        Features::cfg_target_has_reliable_f16_f128,
59    ),
60    (
61        sym::target_has_reliable_f128_math,
62        sym::cfg_target_has_reliable_f16_f128,
63        Features::cfg_target_has_reliable_f16_f128,
64    ),
65];
66
67/// Find a gated cfg determined by the `pred`icate which is given the cfg's name.
68pub fn find_gated_cfg(pred: impl Fn(Symbol) -> bool) -> Option<&'static GatedCfg> {
69    GATED_CFGS.iter().find(|(cfg_sym, ..)| pred(*cfg_sym))
70}
71
72// If you change this, please modify `src/doc/unstable-book` as well. You must
73// move that documentation into the relevant place in the other docs, and
74// remove the chapter on the flag.
75
76#[derive(Copy, Clone, PartialEq, Debug)]
77pub enum AttributeType {
78    /// Normal, builtin attribute that is consumed
79    /// by the compiler before the unused_attribute check
80    Normal,
81
82    /// Builtin attribute that is only allowed at the crate level
83    CrateLevel,
84}
85
86#[derive(Copy, Clone, PartialEq, Debug)]
87pub enum AttributeSafety {
88    /// Normal attribute that does not need `#[unsafe(...)]`
89    Normal,
90
91    /// Unsafe attribute that requires safety obligations to be discharged.
92    ///
93    /// An error is emitted when `#[unsafe(...)]` is omitted, except when the attribute's edition
94    /// is less than the one stored in `unsafe_since`. This handles attributes that were safe in
95    /// earlier editions, but become unsafe in later ones.
96    Unsafe { unsafe_since: Option<Edition> },
97}
98
99#[derive(Clone, Debug, Copy)]
100pub enum AttributeGate {
101    /// A gated attribute which requires a feature gate to be enabled.
102    Gated {
103        /// The feature gate, for example `#![feature(rustc_attrs)]` for rustc_* attributes.
104        feature: Symbol,
105        /// The error message displayed when an attempt is made to use the attribute without its feature gate.
106        message: &'static str,
107        /// Check function to be called during the `PostExpansionVisitor` pass.
108        check: fn(&Features) -> bool,
109        /// Notes to be displayed when an attempt is made to use the attribute without its feature gate.
110        notes: &'static [&'static str],
111    },
112    /// Ungated attribute, can be used on all release channels
113    Ungated,
114}
115
116// FIXME(jdonszelmann): move to rustc_hir::attrs
117/// A template that the attribute input must match.
118/// Only top-level shape (`#[attr]` vs `#[attr(...)]` vs `#[attr = ...]`) is considered now.
119#[derive(Clone, Copy, Default)]
120pub struct AttributeTemplate {
121    /// If `true`, the attribute is allowed to be a bare word like `#[test]`.
122    pub word: bool,
123    /// If `Some`, the attribute is allowed to take a list of items like `#[allow(..)]`.
124    pub list: Option<&'static [&'static str]>,
125    /// If non-empty, the attribute is allowed to take a list containing exactly
126    /// one of the listed words, like `#[coverage(off)]`.
127    pub one_of: &'static [Symbol],
128    /// If `Some`, the attribute is allowed to be a name/value pair where the
129    /// value is a string, like `#[must_use = "reason"]`.
130    pub name_value_str: Option<&'static [&'static str]>,
131    /// A link to the document for this attribute.
132    pub docs: Option<&'static str>,
133}
134
135impl AttributeTemplate {
136    pub fn suggestions(
137        &self,
138        style: Option<AttrStyle>,
139        name: impl std::fmt::Display,
140    ) -> Vec<String> {
141        let mut suggestions = vec![];
142        let (start, end) = match style {
143            Some(AttrStyle::Outer) => ("#[", "]"),
144            Some(AttrStyle::Inner) => ("#![", "]"),
145            None => ("", ""),
146        };
147        if self.word {
148            suggestions.push(format!("{start}{name}{end}"));
149        }
150        if let Some(descr) = self.list {
151            for descr in descr {
152                suggestions.push(format!("{start}{name}({descr}){end}"));
153            }
154        }
155        suggestions.extend(self.one_of.iter().map(|&word| format!("{start}{name}({word}){end}")));
156        if let Some(descr) = self.name_value_str {
157            for descr in descr {
158                suggestions.push(format!("{start}{name} = \"{descr}\"{end}"));
159            }
160        }
161        suggestions.sort();
162
163        suggestions
164    }
165}
166
167/// How to handle multiple duplicate attributes on the same item.
168#[derive(Clone, Copy, Default)]
169pub enum AttributeDuplicates {
170    /// Duplicates of this attribute are allowed.
171    ///
172    /// This should only be used with attributes where duplicates have semantic
173    /// meaning, or some kind of "additive" behavior. For example, `#[warn(..)]`
174    /// can be specified multiple times, and it combines all the entries. Or use
175    /// this if there is validation done elsewhere.
176    #[default]
177    DuplicatesOk,
178    /// Duplicates after the first attribute will be an unused_attribute warning.
179    ///
180    /// This is usually used for "word" attributes, where they are used as a
181    /// boolean marker, like `#[used]`. It is not necessarily wrong that there
182    /// are duplicates, but the others should probably be removed.
183    WarnFollowing,
184    /// Same as `WarnFollowing`, but only issues warnings for word-style attributes.
185    ///
186    /// This is only for special cases, for example multiple `#[macro_use]` can
187    /// be warned, but multiple `#[macro_use(...)]` should not because the list
188    /// form has different meaning from the word form.
189    WarnFollowingWordOnly,
190    /// Duplicates after the first attribute will be an error.
191    ///
192    /// This should be used where duplicates would be ignored, but carry extra
193    /// meaning that could cause confusion. For example, `#[stable(since="1.0")]
194    /// #[stable(since="2.0")]`, which version should be used for `stable`?
195    ErrorFollowing,
196    /// Duplicates preceding the last instance of the attribute will be an error.
197    ///
198    /// This is the same as `ErrorFollowing`, except the last attribute is the
199    /// one that is "used". This is typically used in cases like codegen
200    /// attributes which usually only honor the last attribute.
201    ErrorPreceding,
202    /// Duplicates after the first attribute will be an unused_attribute warning
203    /// with a note that this will be an error in the future.
204    ///
205    /// This should be used for attributes that should be `ErrorFollowing`, but
206    /// because older versions of rustc silently accepted (and ignored) the
207    /// attributes, this is used to transition.
208    FutureWarnFollowing,
209    /// Duplicates preceding the last instance of the attribute will be a
210    /// warning, with a note that this will be an error in the future.
211    ///
212    /// This is the same as `FutureWarnFollowing`, except the last attribute is
213    /// the one that is "used". Ideally these can eventually migrate to
214    /// `ErrorPreceding`.
215    FutureWarnPreceding,
216}
217
218/// A convenience macro for constructing attribute templates.
219/// E.g., `template!(Word, List: "description")` means that the attribute
220/// supports forms `#[attr]` and `#[attr(description)]`.
221#[macro_export]
222macro_rules! template {
223    (Word) => { $crate::template!(@ true, None, &[], None, None) };
224    (Word, $link: literal) => { $crate::template!(@ true, None, &[], None, Some($link)) };
225    (List: $descr: expr) => { $crate::template!(@ false, Some($descr), &[], None, None) };
226    (List: $descr: expr, $link: literal) => { $crate::template!(@ false, Some($descr), &[], None, Some($link)) };
227    (OneOf: $one_of: expr) => { $crate::template!(@ false, None, $one_of, None, None) };
228    (NameValueStr: [$($descr: literal),* $(,)?]) => { $crate::template!(@ false, None, &[], Some(&[$($descr,)*]), None) };
229    (NameValueStr: [$($descr: literal),* $(,)?], $link: literal) => { $crate::template!(@ false, None, &[], Some(&[$($descr,)*]), Some($link)) };
230    (NameValueStr: $descr: literal) => { $crate::template!(@ false, None, &[], Some(&[$descr]), None) };
231    (NameValueStr: $descr: literal, $link: literal) => { $crate::template!(@ false, None, &[], Some(&[$descr]), Some($link)) };
232    (Word, List: $descr: expr) => { $crate::template!(@ true, Some($descr), &[], None, None) };
233    (Word, List: $descr: expr, $link: literal) => { $crate::template!(@ true, Some($descr), &[], None, Some($link)) };
234    (Word, NameValueStr: $descr: expr) => { $crate::template!(@ true, None, &[], Some(&[$descr]), None) };
235    (Word, NameValueStr: $descr: expr, $link: literal) => { $crate::template!(@ true, None, &[], Some(&[$descr]), Some($link)) };
236    (List: $descr1: expr, NameValueStr: $descr2: expr) => {
237        $crate::template!(@ false, Some($descr1), &[], Some(&[$descr2]), None)
238    };
239    (List: $descr1: expr, NameValueStr: $descr2: expr, $link: literal) => {
240        $crate::template!(@ false, Some($descr1), &[], Some(&[$descr2]), Some($link))
241    };
242    (Word, List: $descr1: expr, NameValueStr: $descr2: expr) => {
243        $crate::template!(@ true, Some($descr1), &[], Some(&[$descr2]), None)
244    };
245    (Word, List: $descr1: expr, NameValueStr: $descr2: expr, $link: literal) => {
246        $crate::template!(@ true, Some($descr1), &[], Some(&[$descr2]), Some($link))
247    };
248    (@ $word: expr, $list: expr, $one_of: expr, $name_value_str: expr, $link: expr) => { $crate::AttributeTemplate {
249        word: $word, list: $list, one_of: $one_of, name_value_str: $name_value_str, docs: $link,
250    } };
251}
252
253macro_rules! ungated {
254    (unsafe($edition:ident) $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
255        BuiltinAttribute {
256            name: sym::$attr,
257            encode_cross_crate: $encode_cross_crate,
258            type_: $typ,
259            safety: AttributeSafety::Unsafe { unsafe_since: Some(Edition::$edition) },
260            template: $tpl,
261            gate: Ungated,
262            duplicates: $duplicates,
263        }
264    };
265    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
266        BuiltinAttribute {
267            name: sym::$attr,
268            encode_cross_crate: $encode_cross_crate,
269            type_: $typ,
270            safety: AttributeSafety::Unsafe { unsafe_since: None },
271            template: $tpl,
272            gate: Ungated,
273            duplicates: $duplicates,
274        }
275    };
276    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr $(,)?) => {
277        BuiltinAttribute {
278            name: sym::$attr,
279            encode_cross_crate: $encode_cross_crate,
280            type_: $typ,
281            safety: AttributeSafety::Normal,
282            template: $tpl,
283            gate: Ungated,
284            duplicates: $duplicates,
285        }
286    };
287}
288
289macro_rules! gated {
290    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $gate:ident, $message:expr $(,)?) => {
291        BuiltinAttribute {
292            name: sym::$attr,
293            encode_cross_crate: $encode_cross_crate,
294            type_: $typ,
295            safety: AttributeSafety::Unsafe { unsafe_since: None },
296            template: $tpl,
297            duplicates: $duplicates,
298            gate: Gated {
299                feature: sym::$gate,
300                message: $message,
301                check: Features::$gate,
302                notes: &[],
303            },
304        }
305    };
306    (unsafe $attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $message:expr $(,)?) => {
307        BuiltinAttribute {
308            name: sym::$attr,
309            encode_cross_crate: $encode_cross_crate,
310            type_: $typ,
311            safety: AttributeSafety::Unsafe { unsafe_since: None },
312            template: $tpl,
313            duplicates: $duplicates,
314            gate: Gated {
315                feature: sym::$attr,
316                message: $message,
317                check: Features::$attr,
318                notes: &[],
319            },
320        }
321    };
322    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $gate:ident, $message:expr $(,)?) => {
323        BuiltinAttribute {
324            name: sym::$attr,
325            encode_cross_crate: $encode_cross_crate,
326            type_: $typ,
327            safety: AttributeSafety::Normal,
328            template: $tpl,
329            duplicates: $duplicates,
330            gate: Gated {
331                feature: sym::$gate,
332                message: $message,
333                check: Features::$gate,
334                notes: &[],
335            },
336        }
337    };
338    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $message:expr $(,)?) => {
339        BuiltinAttribute {
340            name: sym::$attr,
341            encode_cross_crate: $encode_cross_crate,
342            type_: $typ,
343            safety: AttributeSafety::Normal,
344            template: $tpl,
345            duplicates: $duplicates,
346            gate: Gated {
347                feature: sym::$attr,
348                message: $message,
349                check: Features::$attr,
350                notes: &[],
351            },
352        }
353    };
354}
355
356macro_rules! rustc_attr {
357    (TEST, $attr:ident, $typ:expr, $tpl:expr, $duplicate:expr, $encode_cross_crate:expr $(,)?) => {
358        rustc_attr!(
359            $attr,
360            $typ,
361            $tpl,
362            $duplicate,
363            $encode_cross_crate,
364            concat!(
365                "the `#[",
366                stringify!($attr),
367                "]` attribute is used for rustc unit tests"
368            ),
369        )
370    };
371    ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $encode_cross_crate:expr, $($notes:expr),* $(,)?) => {
372        BuiltinAttribute {
373            name: sym::$attr,
374            encode_cross_crate: $encode_cross_crate,
375            type_: $typ,
376            safety: AttributeSafety::Normal,
377            template: $tpl,
378            duplicates: $duplicates,
379            gate: Gated {
380                feature: sym::rustc_attrs,
381                message: "use of an internal attribute",
382                check: Features::rustc_attrs,
383                notes: &[
384                    concat!("the `#[",
385                    stringify!($attr),
386                    "]` attribute is an internal implementation detail that will never be stable"),
387                    $($notes),*
388                    ]
389            },
390        }
391    };
392}
393
394macro_rules! experimental {
395    ($attr:ident) => {
396        concat!("the `#[", stringify!($attr), "]` attribute is an experimental feature")
397    };
398}
399
400pub struct BuiltinAttribute {
401    pub name: Symbol,
402    /// Whether this attribute is encode cross crate.
403    ///
404    /// If so, it is encoded in the crate metadata.
405    /// Otherwise, it can only be used in the local crate.
406    pub encode_cross_crate: EncodeCrossCrate,
407    pub type_: AttributeType,
408    pub safety: AttributeSafety,
409    pub template: AttributeTemplate,
410    pub duplicates: AttributeDuplicates,
411    pub gate: AttributeGate,
412}
413
414/// Attributes that have a special meaning to rustc or rustdoc.
415#[rustfmt::skip]
416pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
417    // ==========================================================================
418    // Stable attributes:
419    // ==========================================================================
420
421    // Conditional compilation:
422    ungated!(
423        cfg, Normal,
424        template!(
425            List: &["predicate"],
426            "https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg-attribute"
427        ),
428        DuplicatesOk, EncodeCrossCrate::Yes
429    ),
430    ungated!(
431        cfg_attr, Normal,
432        template!(
433            List: &["predicate, attr1, attr2, ..."],
434            "https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute"
435        ),
436        DuplicatesOk, EncodeCrossCrate::Yes
437    ),
438
439    // Testing:
440    ungated!(
441        ignore, Normal,
442        template!(
443            Word,
444            NameValueStr: "reason",
445            "https://doc.rust-lang.org/reference/attributes/testing.html#the-ignore-attribute"
446        ),
447        WarnFollowing, EncodeCrossCrate::No,
448    ),
449    ungated!(
450        should_panic, Normal,
451        template!(
452            Word,
453            List: &[r#"expected = "reason""#],
454            NameValueStr: "reason",
455            "https://doc.rust-lang.org/reference/attributes/testing.html#the-should_panic-attribute"
456        ),
457        FutureWarnFollowing, EncodeCrossCrate::No,
458    ),
459    // FIXME(Centril): This can be used on stable but shouldn't.
460    ungated!(
461        reexport_test_harness_main, CrateLevel, template!(NameValueStr: "name"), ErrorFollowing,
462        EncodeCrossCrate::No,
463    ),
464
465    // Macros:
466    ungated!(
467        automatically_derived, Normal,
468        template!(
469            Word,
470            "https://doc.rust-lang.org/reference/attributes/derive.html#the-automatically_derived-attribute"
471        ),
472        WarnFollowing, EncodeCrossCrate::Yes
473    ),
474    ungated!(
475        macro_use, Normal,
476        template!(
477            Word,
478            List: &["name1, name2, ..."],
479            "https://doc.rust-lang.org/reference/macros-by-example.html#the-macro_use-attribute"
480        ),
481        WarnFollowingWordOnly, EncodeCrossCrate::No,
482    ),
483    ungated!(macro_escape, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No), // Deprecated synonym for `macro_use`.
484    ungated!(
485        macro_export, Normal,
486        template!(
487            Word,
488            List: &["local_inner_macros"],
489            "https://doc.rust-lang.org/reference/macros-by-example.html#path-based-scope"
490        ),
491        WarnFollowing, EncodeCrossCrate::Yes
492    ),
493    ungated!(
494        proc_macro, Normal,
495        template!(
496            Word,
497            "https://doc.rust-lang.org/reference/procedural-macros.html#function-like-procedural-macros"),
498        ErrorFollowing, EncodeCrossCrate::No
499    ),
500    ungated!(
501        proc_macro_derive, Normal,
502        template!(
503            List: &["TraitName", "TraitName, attributes(name1, name2, ...)"],
504            "https://doc.rust-lang.org/reference/procedural-macros.html#derive-macros"
505        ),
506        ErrorFollowing, EncodeCrossCrate::No,
507    ),
508    ungated!(
509        proc_macro_attribute, Normal,
510        template!(Word, "https://doc.rust-lang.org/reference/procedural-macros.html#attribute-macros"),
511        ErrorFollowing, EncodeCrossCrate::No
512    ),
513
514    // Lints:
515    ungated!(
516        warn, Normal,
517        template!(
518            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
519            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
520        ),
521        DuplicatesOk, EncodeCrossCrate::No,
522    ),
523    ungated!(
524        allow, Normal,
525        template!(
526            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
527            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
528        ),
529        DuplicatesOk, EncodeCrossCrate::No,
530    ),
531    ungated!(
532        expect, Normal,
533        template!(
534            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
535            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
536        ),
537        DuplicatesOk, EncodeCrossCrate::No,
538    ),
539    ungated!(
540        forbid, Normal,
541        template!(
542            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
543            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
544        ),
545        DuplicatesOk, EncodeCrossCrate::No
546    ),
547    ungated!(
548        deny, Normal,
549        template!(
550            List: &["lint1", "lint1, lint2, ...", r#"lint1, lint2, lint3, reason = "...""#],
551            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#lint-check-attributes"
552        ),
553        DuplicatesOk, EncodeCrossCrate::No
554    ),
555    ungated!(
556        must_use, Normal,
557        template!(
558            Word,
559            NameValueStr: "reason",
560            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute"
561        ),
562        FutureWarnFollowing, EncodeCrossCrate::Yes
563    ),
564    gated!(
565        must_not_suspend, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing,
566        EncodeCrossCrate::Yes, experimental!(must_not_suspend)
567    ),
568    ungated!(
569        deprecated, Normal,
570        template!(
571            Word,
572            List: &[r#"/*opt*/ since = "version", /*opt*/ note = "reason""#],
573            NameValueStr: "reason",
574            "https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute"
575        ),
576        ErrorFollowing, EncodeCrossCrate::Yes
577    ),
578
579    // Crate properties:
580    ungated!(
581        crate_name, CrateLevel,
582        template!(
583            NameValueStr: "name",
584            "https://doc.rust-lang.org/reference/crates-and-source-files.html#the-crate_name-attribute"
585        ),
586        FutureWarnFollowing, EncodeCrossCrate::No,
587    ),
588    ungated!(
589        crate_type, CrateLevel,
590        template!(
591            NameValueStr: ["bin", "lib", "dylib", "cdylib", "rlib", "staticlib", "sdylib", "proc-macro"],
592            "https://doc.rust-lang.org/reference/linkage.html"
593        ),
594        DuplicatesOk, EncodeCrossCrate::No,
595    ),
596
597    // ABI, linking, symbols, and FFI
598    ungated!(
599        link, Normal,
600        template!(List: &[
601            r#"name = "...""#,
602            r#"name = "...", kind = "dylib|static|...""#,
603            r#"name = "...", wasm_import_module = "...""#,
604            r#"name = "...", import_name_type = "decorated|noprefix|undecorated""#,
605            r#"name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated""#,
606        ], "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute"),
607        DuplicatesOk, EncodeCrossCrate::No,
608    ),
609    ungated!(
610        link_name, Normal,
611        template!(NameValueStr: "name", "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_name-attribute"),
612        FutureWarnPreceding, EncodeCrossCrate::Yes
613    ),
614    ungated!(
615        no_link, Normal,
616        template!(Word, "https://doc.rust-lang.org/reference/items/extern-crates.html#the-no_link-attribute"),
617        WarnFollowing, EncodeCrossCrate::No
618    ),
619    ungated!(
620        repr, Normal,
621        template!(
622            List: &["C", "Rust", "transparent", "align(...)", "packed(...)", "<integer type>"],
623            "https://doc.rust-lang.org/reference/type-layout.html#representations"
624        ),
625        DuplicatesOk, EncodeCrossCrate::No
626    ),
627    // FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
628    gated!(rustc_align, Normal, template!(List: &["alignment"]), DuplicatesOk, EncodeCrossCrate::No, fn_align, experimental!(rustc_align)),
629    gated!(rustc_align_static, Normal, template!(List: &["alignment"]), DuplicatesOk, EncodeCrossCrate::No, static_align, experimental!(rustc_align_static)),
630    ungated!(
631        unsafe(Edition2024) export_name, Normal,
632        template!(NameValueStr: "name", "https://doc.rust-lang.org/reference/abi.html#the-export_name-attribute"),
633        FutureWarnPreceding, EncodeCrossCrate::No
634    ),
635    ungated!(
636        unsafe(Edition2024) link_section, Normal,
637        template!(NameValueStr: "name", "https://doc.rust-lang.org/reference/abi.html#the-link_section-attribute"),
638        FutureWarnPreceding, EncodeCrossCrate::No
639    ),
640    ungated!(
641        unsafe(Edition2024) no_mangle, Normal,
642        template!(Word, "https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute"),
643        WarnFollowing, EncodeCrossCrate::No
644    ),
645    ungated!(
646        used, Normal,
647        template!(Word, List: &["compiler", "linker"], "https://doc.rust-lang.org/reference/abi.html#the-used-attribute"),
648        WarnFollowing, EncodeCrossCrate::No
649    ),
650    ungated!(
651        link_ordinal, Normal,
652        template!(List: &["ordinal"], "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_ordinal-attribute"),
653        ErrorPreceding, EncodeCrossCrate::Yes
654    ),
655    ungated!(
656        unsafe naked, Normal,
657        template!(Word, "https://doc.rust-lang.org/reference/attributes/codegen.html#the-naked-attribute"),
658        WarnFollowing, EncodeCrossCrate::No
659    ),
660    // See `TyAndLayout::pass_indirectly_in_non_rustic_abis` for details.
661    rustc_attr!(
662        rustc_pass_indirectly_in_non_rustic_abis, Normal, template!(Word), ErrorFollowing,
663        EncodeCrossCrate::No,
664        "types marked with `#[rustc_pass_indirectly_in_non_rustic_abis]` are always passed indirectly by non-Rustic abis."
665    ),
666
667    // Limits:
668    ungated!(
669        recursion_limit, CrateLevel,
670        template!(NameValueStr: "N", "https://doc.rust-lang.org/reference/attributes/limits.html#the-recursion_limit-attribute"),
671        FutureWarnFollowing, EncodeCrossCrate::No
672    ),
673    ungated!(
674        type_length_limit, CrateLevel,
675        template!(NameValueStr: "N", "https://doc.rust-lang.org/reference/attributes/limits.html#the-type_length_limit-attribute"),
676        FutureWarnFollowing, EncodeCrossCrate::No
677    ),
678    gated!(
679        move_size_limit, CrateLevel, template!(NameValueStr: "N"), ErrorFollowing,
680        EncodeCrossCrate::No, large_assignments, experimental!(move_size_limit)
681    ),
682
683    // Entry point:
684    ungated!(
685        no_main, CrateLevel,
686        template!(Word, "https://doc.rust-lang.org/reference/crates-and-source-files.html#the-no_main-attribute"),
687        WarnFollowing, EncodeCrossCrate::No
688    ),
689
690    // Modules, prelude, and resolution:
691    ungated!(
692        path, Normal,
693        template!(NameValueStr: "file", "https://doc.rust-lang.org/reference/items/modules.html#the-path-attribute"),
694        FutureWarnFollowing, EncodeCrossCrate::No
695    ),
696    ungated!(
697        no_std, CrateLevel,
698        template!(Word, "https://doc.rust-lang.org/reference/names/preludes.html#the-no_std-attribute"),
699        WarnFollowing, EncodeCrossCrate::No
700    ),
701    ungated!(
702        no_implicit_prelude, Normal,
703        template!(Word, "https://doc.rust-lang.org/reference/names/preludes.html#the-no_implicit_prelude-attribute"),
704        WarnFollowing, EncodeCrossCrate::No
705    ),
706    ungated!(
707        non_exhaustive, Normal,
708        template!(Word, "https://doc.rust-lang.org/reference/attributes/type_system.html#the-non_exhaustive-attribute"),
709        WarnFollowing, EncodeCrossCrate::Yes
710    ),
711
712    // Runtime
713    ungated!(
714        windows_subsystem, CrateLevel,
715        template!(NameValueStr: ["windows", "console"], "https://doc.rust-lang.org/reference/runtime.html#the-windows_subsystem-attribute"),
716        FutureWarnFollowing, EncodeCrossCrate::No
717    ),
718    ungated!( // RFC 2070
719        panic_handler, Normal,
720        template!(Word, "https://doc.rust-lang.org/reference/panic.html#the-panic_handler-attribute"),
721        WarnFollowing, EncodeCrossCrate::Yes
722    ),
723
724    // Code generation:
725    ungated!(
726        inline, Normal,
727        template!(
728            Word,
729            List: &["always", "never"],
730            "https://doc.rust-lang.org/reference/attributes/codegen.html#the-inline-attribute"
731        ),
732        FutureWarnFollowing, EncodeCrossCrate::No
733    ),
734    ungated!(
735        cold, Normal,
736        template!(Word, "https://doc.rust-lang.org/reference/attributes/codegen.html#the-cold-attribute"),
737        WarnFollowing, EncodeCrossCrate::No
738    ),
739    ungated!(
740        no_builtins, CrateLevel,
741        template!(Word, "https://doc.rust-lang.org/reference/attributes/codegen.html#the-no_builtins-attribute"),
742        WarnFollowing, EncodeCrossCrate::Yes
743    ),
744    ungated!(
745        target_feature, Normal,
746        template!(List: &[r#"enable = "name""#], "https://doc.rust-lang.org/reference/attributes/codegen.html#the-target_feature-attribute"),
747        DuplicatesOk, EncodeCrossCrate::No,
748    ),
749    ungated!(
750        track_caller, Normal,
751        template!(Word, "https://doc.rust-lang.org/reference/attributes/codegen.html#the-track_caller-attribute"),
752        WarnFollowing, EncodeCrossCrate::Yes
753    ),
754    ungated!(
755        instruction_set, Normal,
756        template!(List: &["set"], "https://doc.rust-lang.org/reference/attributes/codegen.html#the-instruction_set-attribute"),
757        ErrorPreceding, EncodeCrossCrate::No
758    ),
759    gated!(
760        unsafe force_target_feature, Normal, template!(List: &[r#"enable = "name""#]),
761        DuplicatesOk, EncodeCrossCrate::No, effective_target_features, experimental!(force_target_feature)
762    ),
763    gated!(
764        sanitize, Normal, template!(List: &[r#"address = "on|off""#, r#"kernel_address = "on|off""#, r#"cfi = "on|off""#, r#"hwaddress = "on|off""#, r#"kcfi = "on|off""#, r#"memory = "on|off""#, r#"memtag = "on|off""#, r#"shadow_call_stack = "on|off""#, r#"thread = "on|off""#]), ErrorPreceding,
765        EncodeCrossCrate::No, sanitize, experimental!(sanitize),
766    ),
767    gated!(
768        coverage, Normal, template!(OneOf: &[sym::off, sym::on]),
769        ErrorPreceding, EncodeCrossCrate::No,
770        coverage_attribute, experimental!(coverage)
771    ),
772
773    ungated!(
774        doc, Normal,
775        template!(
776            List: &["hidden", "inline"],
777            NameValueStr: "string",
778            "https://doc.rust-lang.org/rustdoc/write-documentation/the-doc-attribute.html"
779        ),
780        DuplicatesOk, EncodeCrossCrate::Yes
781    ),
782
783    // Debugging
784    ungated!(
785        debugger_visualizer, Normal,
786        template!(
787            List: &[r#"natvis_file = "...", gdb_script_file = "...""#],
788            "https://doc.rust-lang.org/reference/attributes/debugger.html#the-debugger_visualizer-attribute"
789        ),
790        DuplicatesOk, EncodeCrossCrate::No
791    ),
792    ungated!(
793        collapse_debuginfo, Normal,
794        template!(
795            List: &["no", "external", "yes"],
796            "https://doc.rust-lang.org/reference/attributes/debugger.html#the-collapse_debuginfo-attribute"
797        ),
798        ErrorFollowing, EncodeCrossCrate::Yes
799    ),
800
801    // ==========================================================================
802    // Unstable attributes:
803    // ==========================================================================
804
805    // Linking:
806    gated!(
807        export_stable, Normal, template!(Word), WarnFollowing,
808        EncodeCrossCrate::No, experimental!(export_stable)
809    ),
810
811    // Testing:
812    gated!(
813        test_runner, CrateLevel, template!(List: &["path"]), ErrorFollowing,
814        EncodeCrossCrate::Yes, custom_test_frameworks,
815        "custom test frameworks are an unstable feature",
816    ),
817    // RFC #1268
818    gated!(
819        marker, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
820        marker_trait_attr, experimental!(marker)
821    ),
822    gated!(
823        thread_local, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
824        "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
825    ),
826    gated!(
827        no_core, CrateLevel, template!(Word), WarnFollowing,
828        EncodeCrossCrate::No, experimental!(no_core)
829    ),
830    // RFC 2412
831    gated!(
832        optimize, Normal, template!(List: &["none", "size", "speed"]), ErrorPreceding,
833        EncodeCrossCrate::No, optimize_attribute, experimental!(optimize)
834    ),
835
836    gated!(
837        unsafe ffi_pure, Normal, template!(Word), WarnFollowing,
838        EncodeCrossCrate::No, experimental!(ffi_pure)
839    ),
840    gated!(
841        unsafe ffi_const, Normal, template!(Word), WarnFollowing,
842        EncodeCrossCrate::No, experimental!(ffi_const)
843    ),
844    gated!(
845        register_tool, CrateLevel, template!(List: &["tool1, tool2, ..."]), DuplicatesOk,
846        EncodeCrossCrate::No, experimental!(register_tool),
847    ),
848
849    // RFC 2632
850    // FIXME(const_trait_impl) remove this
851    gated!(
852        const_trait, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No, const_trait_impl,
853        "`const_trait` is a temporary placeholder for marking a trait that is suitable for `const` \
854        `impls` and all default bodies as `const`, which may be removed or renamed in the \
855        future."
856    ),
857    // lang-team MCP 147
858    gated!(
859        deprecated_safe, Normal, template!(List: &[r#"since = "version", note = "...""#]), ErrorFollowing,
860        EncodeCrossCrate::Yes, experimental!(deprecated_safe),
861    ),
862
863    // `#[cfi_encoding = ""]`
864    gated!(
865        cfi_encoding, Normal, template!(NameValueStr: "encoding"), ErrorPreceding,
866        EncodeCrossCrate::Yes, experimental!(cfi_encoding)
867    ),
868
869    // `#[coroutine]` attribute to be applied to closures to make them coroutines instead
870    gated!(
871        coroutine, Normal, template!(Word), ErrorFollowing,
872        EncodeCrossCrate::No, coroutines, experimental!(coroutine)
873    ),
874
875    // RFC 3543
876    // `#[patchable_function_entry(prefix_nops = m, entry_nops = n)]`
877    gated!(
878        patchable_function_entry, Normal, template!(List: &["prefix_nops = m, entry_nops = n"]), ErrorPreceding,
879        EncodeCrossCrate::Yes, experimental!(patchable_function_entry)
880    ),
881
882    // Probably temporary component of min_generic_const_args.
883    // `#[type_const] const ASSOC: usize;`
884    gated!(
885        type_const, Normal, template!(Word), ErrorFollowing,
886        EncodeCrossCrate::Yes, min_generic_const_args, experimental!(type_const),
887    ),
888
889    // The `#[loop_match]` and `#[const_continue]` attributes are part of the
890    // lang experiment for RFC 3720 tracked in:
891    //
892    // - https://github.com/rust-lang/rust/issues/132306
893    gated!(
894        const_continue, Normal, template!(Word), ErrorFollowing,
895        EncodeCrossCrate::No, loop_match, experimental!(const_continue)
896    ),
897    gated!(
898        loop_match, Normal, template!(Word), ErrorFollowing,
899        EncodeCrossCrate::No, loop_match, experimental!(loop_match)
900    ),
901
902    // The `#[pin_v2]` attribute is part of the `pin_ergonomics` experiment
903    // that allows structurally pinning, tracked in:
904    //
905    // - https://github.com/rust-lang/rust/issues/130494
906    gated!(
907        pin_v2, Normal, template!(Word), ErrorFollowing,
908        EncodeCrossCrate::Yes, pin_ergonomics, experimental!(pin_v2),
909    ),
910
911    // ==========================================================================
912    // Internal attributes: Stability, deprecation, and unsafe:
913    // ==========================================================================
914
915    ungated!(
916        feature, CrateLevel,
917        template!(List: &["name1, name2, ..."]), DuplicatesOk, EncodeCrossCrate::No,
918    ),
919    // DuplicatesOk since it has its own validation
920    ungated!(
921        stable, Normal,
922        template!(List: &[r#"feature = "name", since = "version""#]), DuplicatesOk, EncodeCrossCrate::No,
923    ),
924    ungated!(
925        unstable, Normal,
926        template!(List: &[r#"feature = "name", reason = "...", issue = "N""#]), DuplicatesOk,
927        EncodeCrossCrate::Yes
928    ),
929    ungated!(
930        unstable_feature_bound, Normal, template!(Word, List: &["feat1, feat2, ..."]),
931        DuplicatesOk, EncodeCrossCrate::No,
932    ),
933    ungated!(
934        rustc_const_unstable, Normal, template!(List: &[r#"feature = "name""#]),
935        DuplicatesOk, EncodeCrossCrate::Yes
936    ),
937    ungated!(
938        rustc_const_stable, Normal,
939        template!(List: &[r#"feature = "name""#]), DuplicatesOk, EncodeCrossCrate::No,
940    ),
941    ungated!(
942        rustc_default_body_unstable, Normal,
943        template!(List: &[r#"feature = "name", reason = "...", issue = "N""#]),
944        DuplicatesOk, EncodeCrossCrate::No
945    ),
946    gated!(
947        allow_internal_unstable, Normal, template!(Word, List: &["feat1, feat2, ..."]),
948        DuplicatesOk, EncodeCrossCrate::Yes,
949        "allow_internal_unstable side-steps feature gating and stability checks",
950    ),
951    gated!(
952        allow_internal_unsafe, Normal, template!(Word), WarnFollowing,
953        EncodeCrossCrate::No, "allow_internal_unsafe side-steps the unsafe_code lint",
954    ),
955    rustc_attr!(
956        rustc_allowed_through_unstable_modules, Normal, template!(NameValueStr: "deprecation message"),
957        WarnFollowing, EncodeCrossCrate::No,
958        "rustc_allowed_through_unstable_modules special cases accidental stabilizations of stable items \
959        through unstable paths"
960    ),
961    rustc_attr!(
962        rustc_deprecated_safe_2024, Normal, template!(List: &[r#"audit_that = "...""#]),
963        ErrorFollowing, EncodeCrossCrate::Yes,
964        "`#[rustc_deprecated_safe_2024]` is used to declare functions unsafe across the edition 2024 boundary",
965    ),
966    rustc_attr!(
967        rustc_pub_transparent, Normal, template!(Word),
968        ErrorFollowing, EncodeCrossCrate::Yes,
969        "used internally to mark types with a `transparent` representation when it is guaranteed by the documentation",
970    ),
971
972
973    // ==========================================================================
974    // Internal attributes: Type system related:
975    // ==========================================================================
976
977    gated!(fundamental, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes, experimental!(fundamental)),
978    gated!(
979        may_dangle, Normal, template!(Word), WarnFollowing,
980        EncodeCrossCrate::No, dropck_eyepatch,
981        "`may_dangle` has unstable semantics and may be removed in the future",
982    ),
983
984    rustc_attr!(
985        rustc_never_type_options,
986        Normal,
987        template!(List: &[
988            "",
989            r#"fallback = "unit""#,
990            r#"fallback = "niko""#,
991            r#"fallback = "never""#,
992            r#"fallback = "no""#,
993        ]),
994        ErrorFollowing,
995        EncodeCrossCrate::No,
996        "`rustc_never_type_options` is used to experiment with never type fallback and work on \
997         never type stabilization"
998    ),
999
1000    // ==========================================================================
1001    // Internal attributes: Runtime related:
1002    // ==========================================================================
1003
1004    rustc_attr!(
1005        rustc_allocator, Normal, template!(Word), WarnFollowing,
1006        EncodeCrossCrate::No,
1007    ),
1008    rustc_attr!(
1009        rustc_nounwind, Normal, template!(Word), WarnFollowing,
1010        EncodeCrossCrate::No,
1011    ),
1012    rustc_attr!(
1013        rustc_reallocator, Normal, template!(Word), WarnFollowing,
1014        EncodeCrossCrate::No,
1015    ),
1016    rustc_attr!(
1017        rustc_deallocator, Normal, template!(Word), WarnFollowing,
1018        EncodeCrossCrate::No,
1019    ),
1020    rustc_attr!(
1021        rustc_allocator_zeroed, Normal, template!(Word), WarnFollowing,
1022        EncodeCrossCrate::No,
1023    ),
1024    rustc_attr!(
1025        rustc_allocator_zeroed_variant, Normal, template!(NameValueStr: "function"), ErrorPreceding,
1026        EncodeCrossCrate::Yes,
1027    ),
1028    gated!(
1029        default_lib_allocator, Normal, template!(Word), WarnFollowing,
1030        EncodeCrossCrate::No, allocator_internals, experimental!(default_lib_allocator),
1031    ),
1032    gated!(
1033        needs_allocator, Normal, template!(Word), WarnFollowing,
1034        EncodeCrossCrate::No, allocator_internals, experimental!(needs_allocator),
1035    ),
1036    gated!(
1037        panic_runtime, CrateLevel, template!(Word), WarnFollowing,
1038        EncodeCrossCrate::No, experimental!(panic_runtime)
1039    ),
1040    gated!(
1041        needs_panic_runtime, CrateLevel, template!(Word), WarnFollowing,
1042        EncodeCrossCrate::No, experimental!(needs_panic_runtime)
1043    ),
1044    gated!(
1045        compiler_builtins, CrateLevel, template!(Word), WarnFollowing,
1046        EncodeCrossCrate::No,
1047        "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \
1048        which contains compiler-rt intrinsics and will never be stable",
1049    ),
1050    gated!(
1051        profiler_runtime, CrateLevel, template!(Word), WarnFollowing,
1052        EncodeCrossCrate::No,
1053        "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \
1054        which contains the profiler runtime and will never be stable",
1055    ),
1056
1057    // ==========================================================================
1058    // Internal attributes, Linkage:
1059    // ==========================================================================
1060
1061    gated!(
1062        linkage, Normal, template!(NameValueStr: [
1063            "available_externally",
1064            "common",
1065            "extern_weak",
1066            "external",
1067            "internal",
1068            "linkonce",
1069            "linkonce_odr",
1070            "weak",
1071            "weak_odr",
1072        ], "https://doc.rust-lang.org/reference/linkage.html"),
1073        ErrorPreceding, EncodeCrossCrate::No,
1074        "the `linkage` attribute is experimental and not portable across platforms",
1075    ),
1076    rustc_attr!(
1077        rustc_std_internal_symbol, Normal, template!(Word), WarnFollowing,
1078        EncodeCrossCrate::No,
1079    ),
1080    rustc_attr!(
1081        rustc_objc_class, Normal, template!(NameValueStr: "ClassName"), ErrorPreceding,
1082        EncodeCrossCrate::No,
1083    ),
1084    rustc_attr!(
1085        rustc_objc_selector, Normal, template!(NameValueStr: "methodName"), ErrorPreceding,
1086        EncodeCrossCrate::No,
1087    ),
1088
1089    // ==========================================================================
1090    // Internal attributes, Macro related:
1091    // ==========================================================================
1092
1093    rustc_attr!(
1094        rustc_builtin_macro, Normal,
1095        template!(Word, List: &["name", "name, /*opt*/ attributes(name1, name2, ...)"]), ErrorFollowing,
1096        EncodeCrossCrate::Yes,
1097    ),
1098    rustc_attr!(
1099        rustc_proc_macro_decls, Normal, template!(Word), WarnFollowing,
1100        EncodeCrossCrate::No,
1101    ),
1102    rustc_attr!(
1103        rustc_macro_transparency, Normal,
1104        template!(NameValueStr: ["transparent", "semiopaque", "opaque"]), ErrorFollowing,
1105        EncodeCrossCrate::Yes, "used internally for testing macro hygiene",
1106    ),
1107    rustc_attr!(
1108        rustc_autodiff, Normal,
1109        template!(Word, List: &[r#""...""#]), DuplicatesOk,
1110        EncodeCrossCrate::Yes,
1111    ),
1112    // Traces that are left when `cfg` and `cfg_attr` attributes are expanded.
1113    // The attributes are not gated, to avoid stability errors, but they cannot be used in stable
1114    // or unstable code directly because `sym::cfg_(attr_)trace` are not valid identifiers, they
1115    // can only be generated by the compiler.
1116    ungated!(
1117        cfg_trace, Normal, template!(Word /* irrelevant */), DuplicatesOk,
1118        EncodeCrossCrate::No
1119    ),
1120    ungated!(
1121        cfg_attr_trace, Normal, template!(Word /* irrelevant */), DuplicatesOk,
1122        EncodeCrossCrate::No
1123    ),
1124
1125    // ==========================================================================
1126    // Internal attributes, Diagnostics related:
1127    // ==========================================================================
1128
1129    rustc_attr!(
1130        rustc_on_unimplemented, Normal,
1131        template!(
1132            List: &[r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#],
1133            NameValueStr: "message"
1134        ),
1135        ErrorFollowing, EncodeCrossCrate::Yes,
1136        "see `#[diagnostic::on_unimplemented]` for the stable equivalent of this attribute"
1137    ),
1138    rustc_attr!(
1139        rustc_confusables, Normal,
1140        template!(List: &[r#""name1", "name2", ..."#]),
1141        ErrorFollowing, EncodeCrossCrate::Yes,
1142    ),
1143    // Enumerates "identity-like" conversion methods to suggest on type mismatch.
1144    rustc_attr!(
1145        rustc_conversion_suggestion, Normal, template!(Word),
1146        WarnFollowing, EncodeCrossCrate::Yes,
1147    ),
1148    // Prevents field reads in the marked trait or method to be considered
1149    // during dead code analysis.
1150    rustc_attr!(
1151        rustc_trivial_field_reads, Normal, template!(Word),
1152        WarnFollowing, EncodeCrossCrate::Yes,
1153    ),
1154    // Used by the `rustc::potential_query_instability` lint to warn methods which
1155    // might not be stable during incremental compilation.
1156    rustc_attr!(
1157        rustc_lint_query_instability, Normal, template!(Word),
1158        WarnFollowing, EncodeCrossCrate::Yes,
1159    ),
1160    // Used by the `rustc::untracked_query_information` lint to warn methods which
1161    // might not be stable during incremental compilation.
1162    rustc_attr!(
1163        rustc_lint_untracked_query_information, Normal, template!(Word),
1164        WarnFollowing, EncodeCrossCrate::Yes,
1165    ),
1166    // Used by the `rustc::diagnostic_outside_of_impl` lints to assist in changes to diagnostic
1167    // APIs. Any function with this attribute will be checked by that lint.
1168    rustc_attr!(
1169        rustc_lint_diagnostics, Normal, template!(Word),
1170        WarnFollowing, EncodeCrossCrate::Yes,
1171    ),
1172    // Used by the `rustc::bad_opt_access` lint to identify `DebuggingOptions` and `CodegenOptions`
1173    // types (as well as any others in future).
1174    rustc_attr!(
1175        rustc_lint_opt_ty, Normal, template!(Word),
1176        WarnFollowing, EncodeCrossCrate::Yes,
1177    ),
1178    // Used by the `rustc::bad_opt_access` lint on fields
1179    // types (as well as any others in future).
1180    rustc_attr!(
1181        rustc_lint_opt_deny_field_access, Normal, template!(List: &["message"]),
1182        WarnFollowing, EncodeCrossCrate::Yes,
1183    ),
1184
1185    // ==========================================================================
1186    // Internal attributes, Const related:
1187    // ==========================================================================
1188
1189    rustc_attr!(
1190        rustc_promotable, Normal, template!(Word), WarnFollowing,
1191        EncodeCrossCrate::No, ),
1192    rustc_attr!(
1193        rustc_legacy_const_generics, Normal, template!(List: &["N"]), ErrorFollowing,
1194        EncodeCrossCrate::Yes,
1195    ),
1196    // Do not const-check this function's body. It will always get replaced during CTFE via `hook_special_const_fn`.
1197    rustc_attr!(
1198        rustc_do_not_const_check, Normal, template!(Word), WarnFollowing,
1199        EncodeCrossCrate::Yes, "`#[rustc_do_not_const_check]` skips const-check for this function's body",
1200    ),
1201    rustc_attr!(
1202        rustc_const_stable_indirect, Normal,
1203        template!(Word),
1204        WarnFollowing,
1205        EncodeCrossCrate::No,
1206        "this is an internal implementation detail",
1207    ),
1208    rustc_attr!(
1209        rustc_intrinsic_const_stable_indirect, Normal,
1210        template!(Word), WarnFollowing, EncodeCrossCrate::No,  "this is an internal implementation detail",
1211    ),
1212    gated!(
1213        rustc_allow_const_fn_unstable, Normal,
1214        template!(Word, List: &["feat1, feat2, ..."]), DuplicatesOk, EncodeCrossCrate::No,
1215        "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
1216    ),
1217
1218    // ==========================================================================
1219    // Internal attributes, Layout related:
1220    // ==========================================================================
1221
1222    rustc_attr!(
1223        rustc_layout_scalar_valid_range_start, Normal, template!(List: &["value"]), ErrorFollowing,
1224        EncodeCrossCrate::Yes,
1225        "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
1226        niche optimizations in the standard library",
1227    ),
1228    rustc_attr!(
1229        rustc_layout_scalar_valid_range_end, Normal, template!(List: &["value"]), ErrorFollowing,
1230        EncodeCrossCrate::Yes,
1231        "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
1232        niche optimizations in the standard library",
1233    ),
1234    rustc_attr!(
1235        rustc_simd_monomorphize_lane_limit, Normal, template!(NameValueStr: "N"), ErrorFollowing,
1236        EncodeCrossCrate::Yes,
1237        "the `#[rustc_simd_monomorphize_lane_limit]` attribute is just used by std::simd \
1238        for better error messages",
1239    ),
1240    rustc_attr!(
1241        rustc_nonnull_optimization_guaranteed, Normal, template!(Word), WarnFollowing,
1242        EncodeCrossCrate::Yes,
1243        "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document \
1244        guaranteed niche optimizations in the standard library",
1245        "the compiler does not even check whether the type indeed is being non-null-optimized; \
1246        it is your responsibility to ensure that the attribute is only used on types that are optimized",
1247    ),
1248
1249    // ==========================================================================
1250    // Internal attributes, Misc:
1251    // ==========================================================================
1252    gated!(
1253        lang, Normal, template!(NameValueStr: "name"), DuplicatesOk, EncodeCrossCrate::No, lang_items,
1254        "lang items are subject to change",
1255    ),
1256    rustc_attr!(
1257        rustc_as_ptr, Normal, template!(Word), ErrorFollowing,
1258        EncodeCrossCrate::Yes,
1259        "`#[rustc_as_ptr]` is used to mark functions returning pointers to their inner allocations."
1260    ),
1261    rustc_attr!(
1262        rustc_pass_by_value, Normal, template!(Word), ErrorFollowing,
1263        EncodeCrossCrate::Yes,
1264        "`#[rustc_pass_by_value]` is used to mark types that must be passed by value instead of reference."
1265    ),
1266    rustc_attr!(
1267        rustc_never_returns_null_ptr, Normal, template!(Word), ErrorFollowing,
1268        EncodeCrossCrate::Yes,
1269        "`#[rustc_never_returns_null_ptr]` is used to mark functions returning non-null pointers."
1270    ),
1271    rustc_attr!(
1272        rustc_no_implicit_autorefs, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes,
1273        "`#[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."
1274    ),
1275    rustc_attr!(
1276        rustc_coherence_is_core, AttributeType::CrateLevel, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1277        "`#![rustc_coherence_is_core]` allows inherent methods on builtin types, only intended to be used in `core`."
1278    ),
1279    rustc_attr!(
1280        rustc_coinductive, AttributeType::Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1281        "`#[rustc_coinductive]` changes a trait to be coinductive, allowing cycles in the trait solver."
1282    ),
1283    rustc_attr!(
1284        rustc_allow_incoherent_impl, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1285        "`#[rustc_allow_incoherent_impl]` has to be added to all impl items of an incoherent inherent impl."
1286    ),
1287    rustc_attr!(
1288        rustc_preserve_ub_checks, AttributeType::CrateLevel, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
1289        "`#![rustc_preserve_ub_checks]` prevents the designated crate from evaluating whether UB checks are enabled when optimizing MIR",
1290    ),
1291    rustc_attr!(
1292        rustc_deny_explicit_impl,
1293        AttributeType::Normal,
1294        template!(Word),
1295        ErrorFollowing,
1296        EncodeCrossCrate::No,
1297        "`#[rustc_deny_explicit_impl]` enforces that a trait can have no user-provided impls"
1298    ),
1299    rustc_attr!(
1300        rustc_do_not_implement_via_object,
1301        AttributeType::Normal,
1302        template!(Word),
1303        ErrorFollowing,
1304        EncodeCrossCrate::No,
1305        "`#[rustc_do_not_implement_via_object]` opts out of the automatic trait impl for trait objects \
1306        (`impl Trait for dyn Trait`)"
1307    ),
1308    rustc_attr!(
1309        rustc_has_incoherent_inherent_impls, AttributeType::Normal, template!(Word),
1310        ErrorFollowing, EncodeCrossCrate::Yes,
1311        "`#[rustc_has_incoherent_inherent_impls]` allows the addition of incoherent inherent impls for \
1312         the given type by annotating all impl items with `#[rustc_allow_incoherent_impl]`."
1313    ),
1314
1315    BuiltinAttribute {
1316        name: sym::rustc_diagnostic_item,
1317        // FIXME: This can be `true` once we always use `tcx.is_diagnostic_item`.
1318        encode_cross_crate: EncodeCrossCrate::Yes,
1319        type_: Normal,
1320        safety: AttributeSafety::Normal,
1321        template: template!(NameValueStr: "name"),
1322        duplicates: ErrorFollowing,
1323        gate: Gated{
1324            feature: sym::rustc_attrs,
1325            message: "use of an internal attribute",
1326            check: Features::rustc_attrs,
1327            notes: &["the `#[rustc_diagnostic_item]` attribute allows the compiler to reference types \
1328            from the standard library for diagnostic purposes"],
1329        },
1330    },
1331    gated!(
1332        // Used in resolve:
1333        prelude_import, Normal, template!(Word), WarnFollowing,
1334        EncodeCrossCrate::No, "`#[prelude_import]` is for use by rustc only",
1335    ),
1336    gated!(
1337        rustc_paren_sugar, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1338        unboxed_closures, "unboxed_closures are still evolving",
1339    ),
1340    rustc_attr!(
1341        rustc_inherit_overflow_checks, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1342        "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \
1343        overflow checking behavior of several functions in the standard library that are inlined \
1344        across crates",
1345    ),
1346    rustc_attr!(
1347        rustc_reservation_impl, Normal,
1348        template!(NameValueStr: "reservation message"), ErrorFollowing, EncodeCrossCrate::Yes,
1349        "the `#[rustc_reservation_impl]` attribute is internally used \
1350        for reserving `impl<T> From<!> for T` as part of the effort to stabilize `!`"
1351    ),
1352    rustc_attr!(
1353        rustc_test_marker, Normal, template!(NameValueStr: "name"), WarnFollowing,
1354        EncodeCrossCrate::No, "the `#[rustc_test_marker]` attribute is used internally to track tests",
1355    ),
1356    rustc_attr!(
1357        rustc_unsafe_specialization_marker, Normal, template!(Word),
1358        WarnFollowing, EncodeCrossCrate::No,
1359        "the `#[rustc_unsafe_specialization_marker]` attribute is used to check specializations"
1360    ),
1361    rustc_attr!(
1362        rustc_specialization_trait, Normal, template!(Word),
1363        WarnFollowing, EncodeCrossCrate::No,
1364        "the `#[rustc_specialization_trait]` attribute is used to check specializations"
1365    ),
1366    rustc_attr!(
1367        rustc_main, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::No,
1368        "the `#[rustc_main]` attribute is used internally to specify test entry point function",
1369    ),
1370    rustc_attr!(
1371        rustc_skip_during_method_dispatch, Normal, template!(List: &["array, boxed_slice"]), ErrorFollowing,
1372        EncodeCrossCrate::No,
1373        "the `#[rustc_skip_during_method_dispatch]` attribute is used to exclude a trait \
1374        from method dispatch when the receiver is of the following type, for compatibility in \
1375        editions < 2021 (array) or editions < 2024 (boxed_slice)."
1376    ),
1377    rustc_attr!(
1378        rustc_must_implement_one_of, Normal, template!(List: &["function1, function2, ..."]),
1379        ErrorFollowing, EncodeCrossCrate::No,
1380        "the `#[rustc_must_implement_one_of]` attribute is used to change minimal complete \
1381        definition of a trait. Its syntax and semantics are highly experimental and will be \
1382        subject to change before stabilization",
1383    ),
1384    rustc_attr!(
1385        rustc_doc_primitive, Normal, template!(NameValueStr: "primitive name"), ErrorFollowing,
1386        EncodeCrossCrate::Yes, "the `#[rustc_doc_primitive]` attribute is used by the standard library \
1387        to provide a way to generate documentation for primitive types",
1388    ),
1389    gated!(
1390        rustc_intrinsic, Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes, intrinsics,
1391        "the `#[rustc_intrinsic]` attribute is used to declare intrinsics as function items",
1392    ),
1393    rustc_attr!(
1394        rustc_no_mir_inline, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes,
1395        "`#[rustc_no_mir_inline]` prevents the MIR inliner from inlining a function while not affecting codegen"
1396    ),
1397    rustc_attr!(
1398        rustc_force_inline, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing, EncodeCrossCrate::Yes,
1399        "`#[rustc_force_inline]` forces a free function to be inlined"
1400    ),
1401
1402    // ==========================================================================
1403    // Internal attributes, Testing:
1404    // ==========================================================================
1405
1406    rustc_attr!(TEST, rustc_effective_visibility, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes),
1407    rustc_attr!(
1408        TEST, rustc_outlives, Normal, template!(Word),
1409        WarnFollowing, EncodeCrossCrate::No
1410    ),
1411    rustc_attr!(
1412        TEST, rustc_capture_analysis, Normal, template!(Word),
1413        WarnFollowing, EncodeCrossCrate::No
1414    ),
1415    rustc_attr!(
1416        TEST, rustc_insignificant_dtor, Normal, template!(Word),
1417        WarnFollowing, EncodeCrossCrate::Yes
1418    ),
1419    rustc_attr!(
1420        TEST, rustc_no_implicit_bounds, CrateLevel, template!(Word),
1421        WarnFollowing, EncodeCrossCrate::No
1422    ),
1423    rustc_attr!(
1424        TEST, rustc_strict_coherence, Normal, template!(Word),
1425        WarnFollowing, EncodeCrossCrate::Yes
1426    ),
1427    rustc_attr!(
1428        TEST, rustc_variance, Normal, template!(Word),
1429        WarnFollowing, EncodeCrossCrate::No
1430    ),
1431    rustc_attr!(
1432        TEST, rustc_variance_of_opaques, Normal, template!(Word),
1433        WarnFollowing, EncodeCrossCrate::No
1434    ),
1435    rustc_attr!(
1436        TEST, rustc_hidden_type_of_opaques, Normal, template!(Word),
1437        WarnFollowing, EncodeCrossCrate::No
1438    ),
1439    rustc_attr!(
1440        TEST, rustc_layout, Normal, template!(List: &["field1, field2, ..."]),
1441        WarnFollowing, EncodeCrossCrate::Yes
1442    ),
1443    rustc_attr!(
1444        TEST, rustc_abi, Normal, template!(List: &["field1, field2, ..."]),
1445        WarnFollowing, EncodeCrossCrate::No
1446    ),
1447    rustc_attr!(
1448        TEST, rustc_regions, Normal, template!(Word),
1449        WarnFollowing, EncodeCrossCrate::No
1450    ),
1451    rustc_attr!(
1452        TEST, rustc_delayed_bug_from_inside_query, Normal,
1453        template!(Word),
1454        WarnFollowing, EncodeCrossCrate::No
1455    ),
1456    rustc_attr!(
1457        TEST, rustc_dump_user_args, Normal, template!(Word),
1458        WarnFollowing, EncodeCrossCrate::No
1459    ),
1460    rustc_attr!(
1461        TEST, rustc_evaluate_where_clauses, Normal, template!(Word), WarnFollowing,
1462        EncodeCrossCrate::Yes
1463    ),
1464    rustc_attr!(
1465        TEST, rustc_if_this_changed, Normal, template!(Word, List: &["DepNode"]), DuplicatesOk,
1466        EncodeCrossCrate::No
1467    ),
1468    rustc_attr!(
1469        TEST, rustc_then_this_would_need, Normal, template!(List: &["DepNode"]), DuplicatesOk,
1470        EncodeCrossCrate::No
1471    ),
1472    rustc_attr!(
1473        TEST, rustc_clean, Normal,
1474        template!(List: &[r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#]),
1475        DuplicatesOk, EncodeCrossCrate::No
1476    ),
1477    rustc_attr!(
1478        TEST, rustc_partition_reused, Normal,
1479        template!(List: &[r#"cfg = "...", module = "...""#]), DuplicatesOk, EncodeCrossCrate::No
1480    ),
1481    rustc_attr!(
1482        TEST, rustc_partition_codegened, Normal,
1483        template!(List: &[r#"cfg = "...", module = "...""#]), DuplicatesOk, EncodeCrossCrate::No
1484    ),
1485    rustc_attr!(
1486        TEST, rustc_expected_cgu_reuse, Normal,
1487        template!(List: &[r#"cfg = "...", module = "...", kind = "...""#]), DuplicatesOk,
1488        EncodeCrossCrate::No
1489    ),
1490    rustc_attr!(
1491        TEST, rustc_symbol_name, Normal, template!(Word),
1492        WarnFollowing, EncodeCrossCrate::No
1493    ),
1494    rustc_attr!(
1495        TEST, rustc_def_path, Normal, template!(Word),
1496        WarnFollowing, EncodeCrossCrate::No
1497    ),
1498    rustc_attr!(
1499        TEST, rustc_mir, Normal, template!(List: &["arg1, arg2, ..."]),
1500        DuplicatesOk, EncodeCrossCrate::Yes
1501    ),
1502    gated!(
1503        custom_mir, Normal, template!(List: &[r#"dialect = "...", phase = "...""#]),
1504        ErrorFollowing, EncodeCrossCrate::No,
1505        "the `#[custom_mir]` attribute is just used for the Rust test suite",
1506    ),
1507    rustc_attr!(
1508        TEST, rustc_dump_item_bounds, Normal, template!(Word),
1509        WarnFollowing, EncodeCrossCrate::No
1510    ),
1511    rustc_attr!(
1512        TEST, rustc_dump_predicates, Normal, template!(Word),
1513        WarnFollowing, EncodeCrossCrate::No
1514    ),
1515    rustc_attr!(
1516        TEST, rustc_dump_def_parents, Normal, template!(Word),
1517        WarnFollowing, EncodeCrossCrate::No
1518    ),
1519    rustc_attr!(
1520        TEST, rustc_object_lifetime_default, Normal, template!(Word),
1521        WarnFollowing, EncodeCrossCrate::No
1522    ),
1523    rustc_attr!(
1524        TEST, rustc_dump_vtable, Normal, template!(Word),
1525        WarnFollowing, EncodeCrossCrate::No
1526    ),
1527    rustc_attr!(
1528        TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/),
1529        DuplicatesOk, EncodeCrossCrate::No
1530    ),
1531    rustc_attr!(
1532        TEST, pattern_complexity_limit, CrateLevel, template!(NameValueStr: "N"),
1533        ErrorFollowing, EncodeCrossCrate::No,
1534    ),
1535];
1536
1537pub fn is_builtin_attr_name(name: Symbol) -> bool {
1538    BUILTIN_ATTRIBUTE_MAP.get(&name).is_some()
1539}
1540
1541/// Whether this builtin attribute is encoded cross crate.
1542/// This means it can be used cross crate.
1543pub fn encode_cross_crate(name: Symbol) -> bool {
1544    if let Some(attr) = BUILTIN_ATTRIBUTE_MAP.get(&name) {
1545        attr.encode_cross_crate == EncodeCrossCrate::Yes
1546    } else {
1547        true
1548    }
1549}
1550
1551pub fn is_valid_for_get_attr(name: Symbol) -> bool {
1552    BUILTIN_ATTRIBUTE_MAP.get(&name).is_some_and(|attr| match attr.duplicates {
1553        WarnFollowing | ErrorFollowing | ErrorPreceding | FutureWarnFollowing
1554        | FutureWarnPreceding => true,
1555        DuplicatesOk | WarnFollowingWordOnly => false,
1556    })
1557}
1558
1559pub static BUILTIN_ATTRIBUTE_MAP: LazyLock<FxHashMap<Symbol, &BuiltinAttribute>> =
1560    LazyLock::new(|| {
1561        let mut map = FxHashMap::default();
1562        for attr in BUILTIN_ATTRIBUTES.iter() {
1563            if map.insert(attr.name, attr).is_some() {
1564                panic!("duplicate builtin attribute `{}`", attr.name);
1565            }
1566        }
1567        map
1568    });
1569
1570pub fn is_stable_diagnostic_attribute(sym: Symbol, _features: &Features) -> bool {
1571    match sym {
1572        sym::on_unimplemented | sym::do_not_recommend => true,
1573        _ => false,
1574    }
1575}
rustc_feature/builtin_attrs.rs

rustc_feature/
builtin_attrs.rs
