rustc_feature/
builtin_attrs.rs

1//! Built-in attributes and `cfg` flag gating.
2
3use std::sync::LazyLock;
4
5use rustc_data_structures::fx::FxHashSet;
6use rustc_span::{Symbol, sym};
7
8use crate::Features;
9
10type GateFn = fn(&Features) -> bool;
11
12pub type GatedCfg = (Symbol, Symbol, GateFn);
13
14/// `cfg(...)`'s that are feature gated.
15const GATED_CFGS: &[GatedCfg] = &[
16    // (name in cfg, feature, function to check if the feature is enabled)
17    (sym::overflow_checks, sym::cfg_overflow_checks, Features::cfg_overflow_checks),
18    (sym::ub_checks, sym::cfg_ub_checks, Features::cfg_ub_checks),
19    (sym::contract_checks, sym::cfg_contract_checks, Features::cfg_contract_checks),
20    (sym::target_thread_local, sym::cfg_target_thread_local, Features::cfg_target_thread_local),
21    (
22        sym::target_has_atomic_load_store,
23        sym::cfg_target_has_atomic,
24        Features::cfg_target_has_atomic,
25    ),
26    (sym::sanitize, sym::cfg_sanitize, Features::cfg_sanitize),
27    (sym::version, sym::cfg_version, Features::cfg_version),
28    (sym::relocation_model, sym::cfg_relocation_model, Features::cfg_relocation_model),
29    (sym::sanitizer_cfi_generalize_pointers, sym::cfg_sanitizer_cfi, Features::cfg_sanitizer_cfi),
30    (sym::sanitizer_cfi_normalize_integers, sym::cfg_sanitizer_cfi, Features::cfg_sanitizer_cfi),
31    // this is consistent with naming of the compiler flag it's for
32    (sym::fmt_debug, sym::fmt_debug, Features::fmt_debug),
33    (
34        sym::target_has_reliable_f16,
35        sym::cfg_target_has_reliable_f16_f128,
36        Features::cfg_target_has_reliable_f16_f128,
37    ),
38    (
39        sym::target_has_reliable_f16_math,
40        sym::cfg_target_has_reliable_f16_f128,
41        Features::cfg_target_has_reliable_f16_f128,
42    ),
43    (
44        sym::target_has_reliable_f16b,
45        sym::cfg_target_has_reliable_f16b,
46        Features::cfg_target_has_reliable_f16b,
47    ),
48    (
49        sym::target_has_reliable_f128,
50        sym::cfg_target_has_reliable_f16_f128,
51        Features::cfg_target_has_reliable_f16_f128,
52    ),
53    (
54        sym::target_has_reliable_f128_math,
55        sym::cfg_target_has_reliable_f16_f128,
56        Features::cfg_target_has_reliable_f16_f128,
57    ),
58    (sym::target_has_threads, sym::cfg_target_has_threads, Features::cfg_target_has_threads),
59    (sym::target_object_format, sym::cfg_target_object_format, Features::cfg_target_object_format),
60];
61
62/// Find a gated cfg matching `name`.
63pub fn find_gated_cfg(name: Symbol) -> Option<&'static GatedCfg> {
64    GATED_CFGS.iter().find(|(cfg_sym, ..)| name == *cfg_sym)
65}
66
67#[derive(#[automatically_derived]#[doc(hidden)]unsafe impl ::core::clone::TrivialClone
    for AttributeStability {
}
#[automatically_derived]impl ::core::clone::Clone for AttributeStability {
    #[inline]
    fn clone(&self) -> Self {
        let _: ::core::clone::AssertParamIsClone<Symbol>;
        let _: ::core::clone::AssertParamIsClone<&'static [&'static str]>;
        *self
    }
}Clone, #[automatically_derived]impl ::core::fmt::Debug for AttributeStability {
    #[inline]
    fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
        match self {
            Self::Unstable { gate_name: __self_0, notes: __self_1 } =>
                ::core::fmt::Formatter::debug_struct_field2_finish(f,
                    "Unstable gate_name notes", __self_0, &__self_1),
            Self::Stable => ::core::fmt::Formatter::write_str(f, "Stable"),
        }
    }
}Debug, #[automatically_derived]impl ::core::marker::Copy for AttributeStability { }Copy)]
68pub enum AttributeStability {
69    /// An attribute that is unstable behind a specified feature gate.
70    Unstable {
71        /// The feature gate, for example `rustc_attrs` for rustc_* attributes.
72        gate_name: Symbol,
73        /// Notes to be displayed when an attempt is made to use the attribute without its feature
74        /// gate.
75        notes: &'static [&'static str],
76    },
77    /// A stable attribute, can be used on all release channels
78    Stable,
79}
80
81/// Attributes that have a special meaning to rustc or rustdoc.
82#[rustfmt::skip]
83pub static BUILTIN_ATTRIBUTES: &[Symbol] = &[
84    // ==========================================================================
85    // Stable attributes:
86    // ==========================================================================
87
88    // Conditional compilation:
89    sym::cfg,
90    sym::cfg_attr,
91
92    // Testing:
93    sym::ignore,
94    sym::should_panic,
95
96    // Macros:
97    sym::automatically_derived,
98    sym::macro_use,
99    sym::macro_escape, // Deprecated synonym for `macro_use`.
100    sym::macro_export,
101    sym::proc_macro,
102    sym::proc_macro_derive,
103    sym::proc_macro_attribute,
104
105    // Lints:
106    sym::warn,
107    sym::allow,
108    sym::expect,
109    sym::forbid,
110    sym::deny,
111    sym::must_use,
112    sym::must_not_suspend,
113    sym::deprecated,
114
115    // Crate properties:
116    sym::crate_name,
117    sym::crate_type,
118
119    // ABI, linking, symbols, and FFI
120    sym::link,
121    sym::link_name,
122    sym::no_link,
123    sym::repr,
124    // FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
125    sym::rustc_align,
126    sym::rustc_align_static,
127    sym::export_name,
128    sym::link_section,
129    sym::no_mangle,
130    sym::used,
131    sym::link_ordinal,
132    sym::naked,
133    // See `TyAndLayout::pass_indirectly_in_non_rustic_abis` for details.
134    sym::rustc_pass_indirectly_in_non_rustic_abis,
135
136    // Limits:
137    sym::recursion_limit,
138    sym::type_length_limit,
139    sym::move_size_limit,
140
141    // Entry point:
142    sym::no_main,
143
144    // Modules, prelude, and resolution:
145    sym::path,
146    sym::no_std,
147    sym::no_implicit_prelude,
148    sym::non_exhaustive,
149
150    // Runtime
151    sym::windows_subsystem,
152    sym::panic_handler, // RFC 2070
153
154    // Code generation:
155    sym::inline,
156    sym::cold,
157    sym::no_builtins,
158    sym::target_feature,
159    sym::track_caller,
160    sym::instruction_set,
161    sym::force_target_feature,
162    sym::sanitize,
163    sym::coverage,
164    sym::optimize,
165
166    sym::doc,
167
168    // Debugging
169    sym::debugger_visualizer,
170    sym::collapse_debuginfo,
171
172    // ==========================================================================
173    // Unstable attributes:
174    // ==========================================================================
175
176    // Linking:
177    sym::export_stable,
178
179    // Testing:
180    sym::test_runner,
181
182    sym::reexport_test_harness_main,
183
184    // RFC #1268
185    sym::marker,
186    sym::thread_local,
187    sym::no_core,
188
189    sym::ffi_pure,
190    sym::ffi_const,
191    sym::register_attribute_tool,
192    sym::register_lint_tool,
193    sym::register_tool,
194    // `#[cfi_encoding = ""]`
195    sym::cfi_encoding,
196
197    // `#[coroutine]` attribute to be applied to closures to make them coroutines instead
198    sym::coroutine,
199
200    // RFC 3543
201    // `#[patchable_function_entry(prefix_nops = m, entry_nops = n)]`
202    sym::patchable_function_entry,
203
204    // The `#[loop_match]` and `#[const_continue]` attributes are part of the
205    // lang experiment for RFC 3720 tracked in:
206    //
207    // - https://github.com/rust-lang/rust/issues/132306
208    sym::const_continue,
209    sym::loop_match,
210
211    // The `#[pin_v2]` attribute is part of the `pin_ergonomics` experiment
212    // that allows structurally pinning, tracked in:
213    //
214    // - https://github.com/rust-lang/rust/issues/130494
215    sym::pin_v2,
216
217    // The `#[rustc_splat]` attribute is part of the `splat` experiment
218    // that improves the ergonomics of function overloading, tracked in:
219    //
220    // - https://github.com/rust-lang/rust/issues/153629
221    sym::rustc_splat,
222
223    // The `#[rustc_unroll]` attribute.
224    //
225    // - https://github.com/rust-lang/rust/pull/156816
226    //
227    // FIXME(#159429): temporarily renamed to mitigate `#[unroll]` nameres ambiguity
228    sym::rustc_unroll,
229
230    // `#[instrument_fn = "on|off"]` to insert or inhibit instrumentation function
231    // calls inside a function, usually around the prologue.
232    //
233    // - https://github.com/rust-lang/rust/issues/157081
234    sym::instrument_fn,
235
236    // The attribute is part of feature `checked_type_aliases`. Its name is but a placeholder.
237    // FIXME(#134963): Temporarily prefixed with `rustc_` to prevent potential name resolution ambiguities.
238    sym::rustc_unchecked_type_alias,
239
240    // ==========================================================================
241    // Internal attributes: Stability, deprecation, and unsafe:
242    // ==========================================================================
243
244    sym::feature,
245    // DuplicatesOk since it has its own validation
246    sym::stable,
247    sym::unstable,
248    sym::unstable_feature_bound,
249    sym::unstable_removed,
250    sym::rustc_const_unstable,
251    sym::rustc_const_stable,
252    sym::rustc_default_body_unstable,
253    sym::allow_internal_unstable,
254    sym::allow_internal_unsafe,
255    sym::rustc_eii_foreign_item,
256    sym::rustc_allowed_through_unstable_modules,
257    sym::rustc_deprecated_safe_2024,
258    sym::rustc_pub_transparent,
259
260    // ==========================================================================
261    // Internal attributes: Type system related:
262    // ==========================================================================
263
264    sym::fundamental,
265    sym::may_dangle,
266
267    // ==========================================================================
268    // Internal attributes: Runtime related:
269    // ==========================================================================
270
271    sym::rustc_allocator,
272    sym::rustc_nounwind,
273    sym::rustc_reallocator,
274    sym::rustc_deallocator,
275    sym::rustc_allocator_zeroed,
276    sym::rustc_allocator_zeroed_variant,
277    sym::default_lib_allocator,
278    sym::needs_allocator,
279    sym::panic_runtime,
280    sym::needs_panic_runtime,
281    sym::compiler_builtins,
282    sym::profiler_runtime,
283
284    // ==========================================================================
285    // Internal attributes, Linkage:
286    // ==========================================================================
287
288    sym::linkage,
289    sym::rustc_std_internal_symbol,
290    sym::rustc_objc_class,
291    sym::rustc_objc_selector,
292
293    // ==========================================================================
294    // Internal attributes, Macro related:
295    // ==========================================================================
296
297    sym::rustc_builtin_macro,
298    sym::rustc_proc_macro_decls,
299    sym::rustc_macro_transparency,
300    sym::rustc_autodiff,
301    sym::rustc_offload_kernel,
302
303    // ==========================================================================
304    // Internal attributes, Diagnostics related:
305    // ==========================================================================
306
307    sym::rustc_on_unimplemented,
308    sym::rustc_confusables,
309    // Enumerates "identity-like" conversion methods to suggest on type mismatch.
310    sym::rustc_conversion_suggestion,
311    // Prevents field reads in the marked trait or method to be considered
312    // during dead code analysis.
313    sym::rustc_trivial_field_reads,
314    // Used by the `rustc::potential_query_instability` lint to warn methods which
315    // might not be stable during incremental compilation.
316    sym::rustc_lint_query_instability,
317    // Used by the `rustc::untracked_query_information` lint to warn methods which
318    // might not be stable during incremental compilation.
319    sym::rustc_lint_untracked_query_information,
320    // Used by the `rustc::bad_opt_access` lint to identify `DebuggingOptions` and `CodegenOptions`
321    // types (as well as any others in future).
322    sym::rustc_lint_opt_ty,
323    // Used by the `rustc::bad_opt_access` lint on fields
324    // types (as well as any others in future).
325    sym::rustc_lint_opt_deny_field_access,
326    sym::rustc_diagnostic_opaque,
327    sym::rustc_assert_variance,
328
329    // ==========================================================================
330    // Internal attributes, Const related:
331    // ==========================================================================
332
333    sym::rustc_always_gca,
334    sym::rustc_promotable,
335    sym::rustc_legacy_const_generics,
336    // Do not const-check this function's body. It will always get replaced during CTFE via `hook_special_const_fn`.
337    sym::rustc_do_not_const_check,
338    sym::rustc_const_stable_indirect,
339    sym::rustc_intrinsic_const_stable_indirect,
340    sym::rustc_allow_const_fn_unstable,
341
342    // ==========================================================================
343    // Internal attributes, Layout related:
344    // ==========================================================================
345
346    sym::rustc_simd_monomorphize_lane_limit,
347    sym::rustc_nonnull_optimization_guaranteed,
348
349    // ==========================================================================
350    // Internal attributes, Misc:
351    // ==========================================================================
352    sym::lang,
353    sym::rustc_as_ptr,
354    sym::rustc_should_not_be_called_on_const_items,
355    sym::rustc_pass_by_value,
356    sym::rustc_never_returns_null_ptr,
357    sym::rustc_no_implicit_autorefs,
358    sym::rustc_coherence_is_core,
359    sym::rustc_coinductive,
360    sym::rustc_comptime,
361    sym::rustc_allow_incoherent_impl,
362    sym::rustc_preserve_ub_checks,
363    sym::rustc_deny_explicit_impl,
364    sym::rustc_dyn_incompatible_trait,
365    sym::rustc_has_incoherent_inherent_impls,
366    sym::rustc_non_const_trait_method,
367    sym::rustc_panics_when_zero,
368
369    sym::rustc_canonical_symbol,
370    sym::rustc_diagnostic_item,
371    sym::prelude_import,
372    sym::rustc_paren_sugar,
373    sym::rustc_inherit_overflow_checks,
374    sym::rustc_test_marker,
375    sym::rustc_allow_lifetime_dependent_specialization,
376    sym::rustc_specialization_trait,
377    sym::rustc_main,
378    sym::rustc_skip_during_method_dispatch,
379    sym::rustc_must_implement_one_of,
380    sym::rustc_doc_primitive,
381    sym::rustc_intrinsic,
382    sym::rustc_no_mir_inline,
383    sym::rustc_force_inline,
384    sym::rustc_scalable_vector,
385    sym::rustc_must_match_exhaustively,
386    sym::rustc_no_writable,
387
388    // ==========================================================================
389    // Internal attributes, Testing:
390    // ==========================================================================
391
392    sym::rustc_show_spans,
393    sym::rustc_effective_visibility,
394    sym::rustc_dump_inferred_outlives,
395    sym::rustc_capture_analysis,
396    sym::rustc_insignificant_dtor,
397    sym::rustc_no_implicit_bounds,
398    sym::rustc_strict_coherence,
399    sym::rustc_dump_variances,
400    sym::rustc_dump_variances_of_opaques,
401    sym::rustc_dump_generics,
402    sym::rustc_dump_hidden_type_of_opaques,
403    sym::rustc_dump_layout,
404    sym::rustc_abi,
405    sym::rustc_regions,
406    sym::rustc_delayed_bug_from_inside_query,
407    sym::rustc_dump_user_args,
408    sym::rustc_evaluate_where_clauses,
409    sym::rustc_if_this_changed,
410    sym::rustc_then_this_would_need,
411    sym::rustc_clean,
412    sym::rustc_partition_reused,
413    sym::rustc_partition_codegened,
414    sym::rustc_expected_cgu_reuse,
415    sym::rustc_dump_symbol_name,
416    sym::rustc_dump_def_path,
417    sym::rustc_mir,
418    sym::custom_mir,
419    sym::rustc_dump_item_bounds,
420    sym::rustc_dump_clauses,
421    sym::rustc_dump_def_parents,
422    sym::rustc_dump_object_lifetime_defaults,
423    sym::rustc_dump_vtable,
424    sym::rustc_dummy,
425    sym::pattern_complexity_limit,
426];
427
428pub fn is_builtin_attr_name(name: Symbol) -> bool {
429    BUILTIN_ATTRIBUTE_SET.contains(&name)
430}
431
432pub static BUILTIN_ATTRIBUTE_SET: LazyLock<FxHashSet<Symbol>> = LazyLock::new(|| {
433    let mut set = FxHashSet::default();
434    for attr in BUILTIN_ATTRIBUTES.iter() {
435        if !set.insert(*attr) {
436            {
    ::core::panicking::panic_fmt(format_args!("duplicate builtin attribute `{0}`",
            attr));
};panic!("duplicate builtin attribute `{}`", attr);
437        }
438    }
439    set
440});
rustc_feature/builtin_attrs.rs

rustc_feature/
builtin_attrs.rs
