1 //! Built-in attributes and `cfg` flag gating.
3 use AttributeDuplicates::*;
7 use crate::{Features, Stability};
9 use rustc_data_structures::fx::FxHashMap;
10 use rustc_span::symbol::{sym, Symbol};
12 use std::lazy::SyncLazy;
14 type GateFn = fn(&Features) -> bool;
18 (|features| features.$field) as GateFn
22 pub type GatedCfg = (Symbol, Symbol, GateFn);
24 /// `cfg(...)`'s that are feature gated.
25 const GATED_CFGS: &[GatedCfg] = &[
26 // (name in cfg, feature, function to check if the feature is enabled)
27 (sym::target_abi, sym::cfg_target_abi, cfg_fn!(cfg_target_abi)),
28 (sym::target_thread_local, sym::cfg_target_thread_local, cfg_fn!(cfg_target_thread_local)),
30 sym::target_has_atomic_equal_alignment,
31 sym::cfg_target_has_atomic_equal_alignment,
32 cfg_fn!(cfg_target_has_atomic_equal_alignment),
34 (sym::target_has_atomic_load_store, sym::cfg_target_has_atomic, cfg_fn!(cfg_target_has_atomic)),
35 (sym::sanitize, sym::cfg_sanitize, cfg_fn!(cfg_sanitize)),
36 (sym::version, sym::cfg_version, cfg_fn!(cfg_version)),
37 (sym::panic, sym::cfg_panic, cfg_fn!(cfg_panic)),
40 /// Find a gated cfg determined by the `pred`icate which is given the cfg's name.
41 pub fn find_gated_cfg(pred: impl Fn(Symbol) -> bool) -> Option<&'static GatedCfg> {
42 GATED_CFGS.iter().find(|(cfg_sym, ..)| pred(*cfg_sym))
45 // If you change this, please modify `src/doc/unstable-book` as well. You must
46 // move that documentation into the relevant place in the other docs, and
47 // remove the chapter on the flag.
49 #[derive(Copy, Clone, PartialEq, Debug)]
50 pub enum AttributeType {
51 /// Normal, builtin attribute that is consumed
52 /// by the compiler before the unused_attribute check
55 /// Builtin attribute that is only allowed at the crate level
59 #[derive(Clone, Copy)]
60 pub enum AttributeGate {
61 /// Is gated by a given feature gate, reason
62 /// and function to check if enabled
63 Gated(Stability, Symbol, &'static str, fn(&Features) -> bool),
65 /// Ungated attribute, can be used on all release channels
70 impl std::fmt::Debug for AttributeGate {
71 fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
73 Self::Gated(ref stab, name, expl, _) => {
74 write!(fmt, "Gated({:?}, {}, {})", stab, name, expl)
76 Self::Ungated => write!(fmt, "Ungated"),
82 fn is_deprecated(&self) -> bool {
83 matches!(*self, Self::Gated(Stability::Deprecated(_, _), ..))
87 /// A template that the attribute input must match.
88 /// Only top-level shape (`#[attr]` vs `#[attr(...)]` vs `#[attr = ...]`) is considered now.
89 #[derive(Clone, Copy, Default)]
90 pub struct AttributeTemplate {
91 /// If `true`, the attribute is allowed to be a bare word like `#[test]`.
93 /// If `Some`, the attribute is allowed to take a list of items like `#[allow(..)]`.
94 pub list: Option<&'static str>,
95 /// If `Some`, the attribute is allowed to be a name/value pair where the
96 /// value is a string, like `#[must_use = "reason"]`.
97 pub name_value_str: Option<&'static str>,
100 /// How to handle multiple duplicate attributes on the same item.
101 #[derive(Clone, Copy, Default)]
102 pub enum AttributeDuplicates {
103 /// Duplicates of this attribute are allowed.
105 /// This should only be used with attributes where duplicates have semantic
106 /// meaning, or some kind of "additive" behavior. For example, `#[warn(..)]`
107 /// can be specified multiple times, and it combines all the entries. Or use
108 /// this if there is validation done elsewhere.
111 /// Duplicates after the first attribute will be an unused_attribute warning.
113 /// This is usually used for "word" attributes, where they are used as a
114 /// boolean marker, like `#[used]`. It is not necessarily wrong that there
115 /// are duplicates, but the others should probably be removed.
117 /// Same as `WarnFollowing`, but only issues warnings for word-style attributes.
119 /// This is only for special cases, for example multiple `#[macro_use]` can
120 /// be warned, but multiple `#[macro_use(...)]` should not because the list
121 /// form has different meaning from the word form.
122 WarnFollowingWordOnly,
123 /// Duplicates after the first attribute will be an error.
125 /// This should be used where duplicates would be ignored, but carry extra
126 /// meaning that could cause confusion. For example, `#[stable(since="1.0")]
127 /// #[stable(since="2.0")]`, which version should be used for `stable`?
129 /// Duplicates preceding the last instance of the attribute will be an error.
131 /// This is the same as `ErrorFollowing`, except the last attribute is the
132 /// one that is "used". This is typically used in cases like codegen
133 /// attributes which usually only honor the last attribute.
135 /// Duplicates after the first attribute will be an unused_attribute warning
136 /// with a note that this will be an error in the future.
138 /// This should be used for attributes that should be `ErrorFollowing`, but
139 /// because older versions of rustc silently accepted (and ignored) the
140 /// attributes, this is used to transition.
142 /// Duplicates preceding the last instance of the attribute will be a
143 /// warning, with a note that this will be an error in the future.
145 /// This is the same as `FutureWarnFollowing`, except the last attribute is
146 /// the one that is "used". Ideally these can eventually migrate to
147 /// `ErrorPreceding`.
151 /// A convenience macro for constructing attribute templates.
152 /// E.g., `template!(Word, List: "description")` means that the attribute
153 /// supports forms `#[attr]` and `#[attr(description)]`.
154 macro_rules! template {
155 (Word) => { template!(@ true, None, None) };
156 (List: $descr: expr) => { template!(@ false, Some($descr), None) };
157 (NameValueStr: $descr: expr) => { template!(@ false, None, Some($descr)) };
158 (Word, List: $descr: expr) => { template!(@ true, Some($descr), None) };
159 (Word, NameValueStr: $descr: expr) => { template!(@ true, None, Some($descr)) };
160 (List: $descr1: expr, NameValueStr: $descr2: expr) => {
161 template!(@ false, Some($descr1), Some($descr2))
163 (Word, List: $descr1: expr, NameValueStr: $descr2: expr) => {
164 template!(@ true, Some($descr1), Some($descr2))
166 (@ $word: expr, $list: expr, $name_value_str: expr) => { AttributeTemplate {
167 word: $word, list: $list, name_value_str: $name_value_str
171 macro_rules! ungated {
172 ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr $(,)?) => {
178 duplicates: $duplicates,
184 ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $gate:ident, $msg:expr $(,)?) => {
189 duplicates: $duplicates,
190 gate: Gated(Stability::Unstable, sym::$gate, $msg, cfg_fn!($gate)),
193 ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $msg:expr $(,)?) => {
198 duplicates: $duplicates,
199 gate: Gated(Stability::Unstable, sym::$attr, $msg, cfg_fn!($attr)),
204 macro_rules! rustc_attr {
205 (TEST, $attr:ident, $typ:expr, $tpl:expr, $duplicate:expr $(,)?) => {
214 "]` attribute is just used for rustc unit tests \
215 and will never be stable",
219 ($attr:ident, $typ:expr, $tpl:expr, $duplicates:expr, $msg:expr $(,)?) => {
224 duplicates: $duplicates,
225 gate: Gated(Stability::Unstable, sym::rustc_attrs, $msg, cfg_fn!(rustc_attrs)),
230 macro_rules! experimental {
232 concat!("the `#[", stringify!($attr), "]` attribute is an experimental feature")
236 const IMPL_DETAIL: &str = "internal implementation detail";
237 const INTERNAL_UNSTABLE: &str = "this is an internal attribute that will never be stable";
239 pub struct BuiltinAttribute {
241 pub type_: AttributeType,
242 pub template: AttributeTemplate,
243 pub duplicates: AttributeDuplicates,
244 pub gate: AttributeGate,
247 /// Attributes that have a special meaning to rustc or rustdoc.
249 pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
250 // ==========================================================================
251 // Stable attributes:
252 // ==========================================================================
254 // Conditional compilation:
255 ungated!(cfg, Normal, template!(List: "predicate"), DuplicatesOk),
256 ungated!(cfg_attr, Normal, template!(List: "predicate, attr1, attr2, ..."), DuplicatesOk),
259 ungated!(ignore, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing),
261 should_panic, Normal,
262 template!(Word, List: r#"expected = "reason"#, NameValueStr: "reason"), FutureWarnFollowing,
264 // FIXME(Centril): This can be used on stable but shouldn't.
265 ungated!(reexport_test_harness_main, CrateLevel, template!(NameValueStr: "name"), ErrorFollowing),
268 ungated!(automatically_derived, Normal, template!(Word), WarnFollowing),
269 ungated!(macro_use, Normal, template!(Word, List: "name1, name2, ..."), WarnFollowingWordOnly),
270 ungated!(macro_escape, Normal, template!(Word), WarnFollowing), // Deprecated synonym for `macro_use`.
271 ungated!(macro_export, Normal, template!(Word, List: "local_inner_macros"), WarnFollowing),
272 ungated!(proc_macro, Normal, template!(Word), ErrorFollowing),
274 proc_macro_derive, Normal,
275 template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)"), ErrorFollowing,
277 ungated!(proc_macro_attribute, Normal, template!(Word), ErrorFollowing),
281 warn, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#), DuplicatesOk
284 allow, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#), DuplicatesOk
287 forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#), DuplicatesOk
290 deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#), DuplicatesOk
292 ungated!(must_use, Normal, template!(Word, NameValueStr: "reason"), FutureWarnFollowing),
294 must_not_suspend, Normal, template!(Word, NameValueStr: "reason"), WarnFollowing,
295 must_not_suspend, experimental!(must_not_suspend)
301 List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#,
302 NameValueStr: "reason"
304 // This has special duplicate handling in E0550 to handle duplicates with rustc_deprecated
309 ungated!(crate_name, CrateLevel, template!(NameValueStr: "name"), FutureWarnFollowing),
310 ungated!(crate_type, CrateLevel, template!(NameValueStr: "bin|lib|..."), FutureWarnFollowing),
311 // crate_id is deprecated
312 ungated!(crate_id, CrateLevel, template!(NameValueStr: "ignored"), FutureWarnFollowing),
314 // ABI, linking, symbols, and FFI
317 template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...""#),
320 ungated!(link_name, Normal, template!(NameValueStr: "name"), FutureWarnPreceding),
321 ungated!(no_link, Normal, template!(Word), WarnFollowing),
322 ungated!(repr, Normal, template!(List: "C"), DuplicatesOk),
323 ungated!(export_name, Normal, template!(NameValueStr: "name"), FutureWarnPreceding),
324 ungated!(link_section, Normal, template!(NameValueStr: "name"), FutureWarnPreceding),
325 ungated!(no_mangle, Normal, template!(Word), WarnFollowing),
326 ungated!(used, Normal, template!(Word, List: "compiler|linker"), WarnFollowing),
329 ungated!(recursion_limit, CrateLevel, template!(NameValueStr: "N"), FutureWarnFollowing),
330 ungated!(type_length_limit, CrateLevel, template!(NameValueStr: "N"), FutureWarnFollowing),
332 const_eval_limit, CrateLevel, template!(NameValueStr: "N"), ErrorFollowing,
333 const_eval_limit, experimental!(const_eval_limit)
336 move_size_limit, CrateLevel, template!(NameValueStr: "N"), ErrorFollowing,
337 large_assignments, experimental!(move_size_limit)
341 ungated!(start, Normal, template!(Word), WarnFollowing),
342 ungated!(no_start, CrateLevel, template!(Word), WarnFollowing),
343 ungated!(no_main, CrateLevel, template!(Word), WarnFollowing),
345 // Modules, prelude, and resolution:
346 ungated!(path, Normal, template!(NameValueStr: "file"), FutureWarnFollowing),
347 ungated!(no_std, CrateLevel, template!(Word), WarnFollowing),
348 ungated!(no_implicit_prelude, Normal, template!(Word), WarnFollowing),
349 ungated!(non_exhaustive, Normal, template!(Word), WarnFollowing),
353 windows_subsystem, CrateLevel,
354 template!(NameValueStr: "windows|console"), FutureWarnFollowing
356 ungated!(panic_handler, Normal, template!(Word), WarnFollowing), // RFC 2070
359 ungated!(inline, Normal, template!(Word, List: "always|never"), FutureWarnFollowing),
360 ungated!(cold, Normal, template!(Word), WarnFollowing),
361 ungated!(no_builtins, CrateLevel, template!(Word), WarnFollowing),
362 ungated!(target_feature, Normal, template!(List: r#"enable = "name""#), DuplicatesOk),
363 ungated!(track_caller, Normal, template!(Word), WarnFollowing),
366 template!(List: "address, memory, thread"), DuplicatesOk,
367 experimental!(no_sanitize)
369 gated!(no_coverage, Normal, template!(Word), WarnFollowing, experimental!(no_coverage)),
372 doc, Normal, template!(List: "hidden|inline|...", NameValueStr: "string"), DuplicatesOk
375 // ==========================================================================
376 // Unstable attributes:
377 // ==========================================================================
380 gated!(naked, Normal, template!(Word), WarnFollowing, naked_functions, experimental!(naked)),
382 link_ordinal, Normal, template!(List: "ordinal"), ErrorPreceding, raw_dylib,
383 experimental!(link_ordinal)
390 template: template!(List: "name"),
391 duplicates: DuplicatesOk,
393 Stability::Deprecated(
394 "https://github.com/rust-lang/rust/pull/64675",
395 Some("may be removed in a future compiler version"),
398 "compiler plugins are deprecated",
405 test_runner, CrateLevel, template!(List: "path"), ErrorFollowing, custom_test_frameworks,
406 "custom test frameworks are an unstable feature",
410 marker, Normal, template!(Word), WarnFollowing, marker_trait_attr, experimental!(marker)
413 thread_local, Normal, template!(Word), WarnFollowing,
414 "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
416 gated!(no_core, CrateLevel, template!(Word), WarnFollowing, experimental!(no_core)),
419 optimize, Normal, template!(List: "size|speed"), ErrorPreceding, optimize_attribute,
420 experimental!(optimize),
424 instruction_set, Normal, template!(List: "set"), ErrorPreceding,
425 isa_attribute, experimental!(instruction_set)
429 ffi_returns_twice, Normal, template!(Word), WarnFollowing, experimental!(ffi_returns_twice)
431 gated!(ffi_pure, Normal, template!(Word), WarnFollowing, experimental!(ffi_pure)),
432 gated!(ffi_const, Normal, template!(Word), WarnFollowing, experimental!(ffi_const)),
434 register_attr, CrateLevel, template!(List: "attr1, attr2, ..."), DuplicatesOk,
435 experimental!(register_attr),
438 register_tool, CrateLevel, template!(List: "tool1, tool2, ..."), DuplicatesOk,
439 experimental!(register_tool),
443 cmse_nonsecure_entry, Normal, template!(Word), WarnFollowing,
444 experimental!(cmse_nonsecure_entry)
448 default_method_body_is_const, Normal, template!(Word), WarnFollowing, const_trait_impl,
449 "`default_method_body_is_const` is a temporary placeholder for declaring default bodies \
450 as `const`, which may be removed or renamed in the future."
453 // ==========================================================================
454 // Internal attributes: Stability, deprecation, and unsafe:
455 // ==========================================================================
457 ungated!(feature, CrateLevel, template!(List: "name1, name1, ..."), DuplicatesOk),
458 // DuplicatesOk since it has its own validation
460 rustc_deprecated, Normal,
461 template!(List: r#"since = "version", reason = "...""#), DuplicatesOk // See E0550
463 // DuplicatesOk since it has its own validation
465 stable, Normal, template!(List: r#"feature = "name", since = "version""#), DuplicatesOk
469 template!(List: r#"feature = "name", reason = "...", issue = "N""#), DuplicatesOk,
471 ungated!(rustc_const_unstable, Normal, template!(List: r#"feature = "name""#), DuplicatesOk),
472 ungated!(rustc_const_stable, Normal, template!(List: r#"feature = "name""#), DuplicatesOk),
474 allow_internal_unstable, Normal, template!(Word, List: "feat1, feat2, ..."), DuplicatesOk,
475 "allow_internal_unstable side-steps feature gating and stability checks",
478 rustc_allow_const_fn_unstable, Normal,
479 template!(Word, List: "feat1, feat2, ..."), DuplicatesOk,
480 "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
483 allow_internal_unsafe, Normal, template!(Word), WarnFollowing,
484 "allow_internal_unsafe side-steps the unsafe_code lint",
487 // ==========================================================================
488 // Internal attributes: Type system related:
489 // ==========================================================================
491 gated!(fundamental, Normal, template!(Word), WarnFollowing, experimental!(fundamental)),
493 may_dangle, Normal, template!(Word), WarnFollowing, dropck_eyepatch,
494 "`may_dangle` has unstable semantics and may be removed in the future",
497 // ==========================================================================
498 // Internal attributes: Runtime related:
499 // ==========================================================================
501 rustc_attr!(rustc_allocator, Normal, template!(Word), WarnFollowing, IMPL_DETAIL),
502 rustc_attr!(rustc_allocator_nounwind, Normal, template!(Word), WarnFollowing, IMPL_DETAIL),
504 alloc_error_handler, Normal, template!(Word), WarnFollowing,
505 experimental!(alloc_error_handler)
508 default_lib_allocator, Normal, template!(Word), WarnFollowing, allocator_internals,
509 experimental!(default_lib_allocator),
512 needs_allocator, Normal, template!(Word), WarnFollowing, allocator_internals,
513 experimental!(needs_allocator),
515 gated!(panic_runtime, Normal, template!(Word), WarnFollowing, experimental!(panic_runtime)),
517 needs_panic_runtime, Normal, template!(Word), WarnFollowing,
518 experimental!(needs_panic_runtime)
521 compiler_builtins, Normal, template!(Word), WarnFollowing,
522 "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \
523 which contains compiler-rt intrinsics and will never be stable",
526 profiler_runtime, Normal, template!(Word), WarnFollowing,
527 "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \
528 which contains the profiler runtime and will never be stable",
531 // ==========================================================================
532 // Internal attributes, Linkage:
533 // ==========================================================================
536 linkage, Normal, template!(NameValueStr: "external|internal|..."), ErrorPreceding,
537 "the `linkage` attribute is experimental and not portable across platforms",
540 rustc_std_internal_symbol, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE
543 // ==========================================================================
544 // Internal attributes, Macro related:
545 // ==========================================================================
548 rustc_builtin_macro, Normal,
549 template!(Word, List: "name, /*opt*/ attributes(name1, name2, ...)"), ErrorFollowing,
552 rustc_attr!(rustc_proc_macro_decls, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
554 rustc_macro_transparency, Normal,
555 template!(NameValueStr: "transparent|semitransparent|opaque"), ErrorFollowing,
556 "used internally for testing macro hygiene",
559 // ==========================================================================
560 // Internal attributes, Diagnostics related:
561 // ==========================================================================
564 rustc_on_unimplemented, Normal,
566 List: r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#,
567 NameValueStr: "message"
572 // Enumerates "identity-like" conversion methods to suggest on type mismatch.
574 rustc_conversion_suggestion, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE
576 // Prevents field reads in the marked trait or method to be considered
577 // during dead code analysis.
579 rustc_trivial_field_reads, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE
581 // Used by the `rustc::potential_query_instability` lint to warn methods which
582 // might not be stable during incremental compilation.
583 rustc_attr!(rustc_lint_query_instability, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
585 // ==========================================================================
586 // Internal attributes, Const related:
587 // ==========================================================================
589 rustc_attr!(rustc_promotable, Normal, template!(Word), WarnFollowing, IMPL_DETAIL),
591 rustc_legacy_const_generics, Normal, template!(List: "N"), ErrorFollowing,
594 // Do not const-check this function's body. It will always get replaced during CTFE.
596 rustc_do_not_const_check, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE
599 // ==========================================================================
600 // Internal attributes, Layout related:
601 // ==========================================================================
604 rustc_layout_scalar_valid_range_start, Normal, template!(List: "value"), ErrorFollowing,
605 "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
606 niche optimizations in libcore and will never be stable",
609 rustc_layout_scalar_valid_range_end, Normal, template!(List: "value"), ErrorFollowing,
610 "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
611 niche optimizations in libcore and will never be stable",
614 rustc_nonnull_optimization_guaranteed, Normal, template!(Word), WarnFollowing,
615 "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable \
616 niche optimizations in libcore and will never be stable",
619 // ==========================================================================
620 // Internal attributes, Misc:
621 // ==========================================================================
623 lang, Normal, template!(NameValueStr: "name"), DuplicatesOk, lang_items,
624 "language items are subject to change",
627 rustc_pass_by_value, Normal,
628 template!(Word), ErrorFollowing,
629 "#[rustc_pass_by_value] is used to mark types that must be passed by value instead of reference."
632 name: sym::rustc_diagnostic_item,
634 template: template!(NameValueStr: "name"),
635 duplicates: ErrorFollowing,
639 "diagnostic items compiler internal support for linting",
640 cfg_fn!(rustc_attrs),
645 prelude_import, Normal, template!(Word), WarnFollowing,
646 "`#[prelude_import]` is for use by rustc only",
649 rustc_paren_sugar, Normal, template!(Word), WarnFollowing, unboxed_closures,
650 "unboxed_closures are still evolving",
653 rustc_inherit_overflow_checks, Normal, template!(Word), WarnFollowing,
654 "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \
655 overflow checking behavior of several libcore functions that are inlined \
656 across crates and will never be stable",
659 rustc_reservation_impl, Normal,
660 template!(NameValueStr: "reservation message"), ErrorFollowing,
661 "the `#[rustc_reservation_impl]` attribute is internally used \
662 for reserving for `for<T> From<!> for T` impl"
665 rustc_test_marker, Normal, template!(Word), WarnFollowing,
666 "the `#[rustc_test_marker]` attribute is used internally to track tests",
669 rustc_unsafe_specialization_marker, Normal, template!(Word), WarnFollowing,
670 "the `#[rustc_unsafe_specialization_marker]` attribute is used to check specializations"
673 rustc_specialization_trait, Normal, template!(Word), WarnFollowing,
674 "the `#[rustc_specialization_trait]` attribute is used to check specializations"
677 rustc_main, Normal, template!(Word), WarnFollowing,
678 "the `#[rustc_main]` attribute is used internally to specify test entry point function",
681 rustc_skip_array_during_method_dispatch, Normal, template!(Word), WarnFollowing,
682 "the `#[rustc_skip_array_during_method_dispatch]` attribute is used to exclude a trait \
683 from method dispatch when the receiver is an array, for compatibility in editions < 2021."
686 rustc_must_implement_one_of, Normal, template!(List: "function1, function2, ..."), ErrorFollowing,
687 "the `#[rustc_must_implement_one_of]` attribute is used to change minimal complete \
688 definition of a trait, it's currently in experimental form and should be changed before \
689 being exposed outside of the std"
692 // ==========================================================================
693 // Internal attributes, Testing:
694 // ==========================================================================
696 rustc_attr!(TEST, rustc_outlives, Normal, template!(Word), WarnFollowing),
697 rustc_attr!(TEST, rustc_capture_analysis, Normal, template!(Word), WarnFollowing),
698 rustc_attr!(TEST, rustc_insignificant_dtor, Normal, template!(Word), WarnFollowing),
699 rustc_attr!(TEST, rustc_strict_coherence, Normal, template!(Word), WarnFollowing),
700 rustc_attr!(TEST, rustc_variance, Normal, template!(Word), WarnFollowing),
701 rustc_attr!(TEST, rustc_layout, Normal, template!(List: "field1, field2, ..."), WarnFollowing),
702 rustc_attr!(TEST, rustc_regions, Normal, template!(Word), WarnFollowing),
704 TEST, rustc_error, Normal,
705 template!(Word, List: "delay_span_bug_from_inside_query"), WarnFollowingWordOnly
707 rustc_attr!(TEST, rustc_dump_user_substs, Normal, template!(Word), WarnFollowing),
708 rustc_attr!(TEST, rustc_evaluate_where_clauses, Normal, template!(Word), WarnFollowing),
710 TEST, rustc_if_this_changed, Normal, template!(Word, List: "DepNode"), DuplicatesOk
713 TEST, rustc_then_this_would_need, Normal, template!(List: "DepNode"), DuplicatesOk
716 TEST, rustc_clean, Normal,
717 template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
721 TEST, rustc_partition_reused, Normal,
722 template!(List: r#"cfg = "...", module = "...""#), DuplicatesOk,
725 TEST, rustc_partition_codegened, Normal,
726 template!(List: r#"cfg = "...", module = "...""#), DuplicatesOk,
729 TEST, rustc_expected_cgu_reuse, Normal,
730 template!(List: r#"cfg = "...", module = "...", kind = "...""#), DuplicatesOk,
732 rustc_attr!(TEST, rustc_symbol_name, Normal, template!(Word), WarnFollowing),
733 rustc_attr!(TEST, rustc_polymorphize_error, Normal, template!(Word), WarnFollowing),
734 rustc_attr!(TEST, rustc_def_path, Normal, template!(Word), WarnFollowing),
735 rustc_attr!(TEST, rustc_mir, Normal, template!(List: "arg1, arg2, ..."), DuplicatesOk),
736 rustc_attr!(TEST, rustc_dump_program_clauses, Normal, template!(Word), WarnFollowing),
737 rustc_attr!(TEST, rustc_dump_env_program_clauses, Normal, template!(Word), WarnFollowing),
738 rustc_attr!(TEST, rustc_object_lifetime_default, Normal, template!(Word), WarnFollowing),
739 rustc_attr!(TEST, rustc_dump_vtable, Normal, template!(Word), WarnFollowing),
740 rustc_attr!(TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/), DuplicatesOk),
742 omit_gdb_pretty_printer_section, Normal, template!(Word), WarnFollowing,
743 "the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite",
747 pub fn deprecated_attributes() -> Vec<&'static BuiltinAttribute> {
748 BUILTIN_ATTRIBUTES.iter().filter(|attr| attr.gate.is_deprecated()).collect()
751 pub fn is_builtin_attr_name(name: Symbol) -> bool {
752 BUILTIN_ATTRIBUTE_MAP.get(&name).is_some()
755 pub static BUILTIN_ATTRIBUTE_MAP: SyncLazy<FxHashMap<Symbol, &BuiltinAttribute>> =
757 let mut map = FxHashMap::default();
758 for attr in BUILTIN_ATTRIBUTES.iter() {
759 if map.insert(attr.name, attr).is_some() {
760 panic!("duplicate builtin attribute `{}`", attr.name);