compiler/rustc_feature/src/builtin_attrs.rs

   1 //! Built-in attributes and `cfg` flag gating.
   2
   3 use AttributeGate::*;
   4 use AttributeType::*;
   5
   6 use crate::{Features, Stability};
   7
   8 use rustc_data_structures::fx::FxHashMap;
   9 use rustc_span::symbol::{sym, Symbol};
  10
  11 use std::lazy::SyncLazy;
  12
  13 type GateFn = fn(&Features) -> bool;
  14
  15 macro_rules! cfg_fn {
  16     ($field: ident) => {
  17         (|features| features.$field) as GateFn
  18     };
  19 }
  20
  21 pub type GatedCfg = (Symbol, Symbol, GateFn);
  22
  23 /// `cfg(...)`'s that are feature gated.
  24 const GATED_CFGS: &[GatedCfg] = &[
  25     // (name in cfg, feature, function to check if the feature is enabled)
  26     (sym::target_abi, sym::cfg_target_abi, cfg_fn!(cfg_target_abi)),
  27     (sym::target_thread_local, sym::cfg_target_thread_local, cfg_fn!(cfg_target_thread_local)),
  28     (sym::target_has_atomic, sym::cfg_target_has_atomic, cfg_fn!(cfg_target_has_atomic)),
  29     (sym::target_has_atomic_load_store, sym::cfg_target_has_atomic, cfg_fn!(cfg_target_has_atomic)),
  30     (
  31         sym::target_has_atomic_equal_alignment,
  32         sym::cfg_target_has_atomic,
  33         cfg_fn!(cfg_target_has_atomic),
  34     ),
  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)),
  38 ];
  39
  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))
  43 }
  44
  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.
  48
  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
  53     Normal,
  54
  55     /// Builtin attribute that may not be consumed by the compiler
  56     /// before the unused_attribute check. These attributes
  57     /// will be ignored by the unused_attribute lint
  58     AssumedUsed,
  59
  60     /// Builtin attribute that is only allowed at the crate level
  61     CrateLevel,
  62 }
  63
  64 #[derive(Clone, Copy)]
  65 pub enum AttributeGate {
  66     /// Is gated by a given feature gate, reason
  67     /// and function to check if enabled
  68     Gated(Stability, Symbol, &'static str, fn(&Features) -> bool),
  69
  70     /// Ungated attribute, can be used on all release channels
  71     Ungated,
  72 }
  73
  74 // fn() is not Debug
  75 impl std::fmt::Debug for AttributeGate {
  76     fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
  77         match *self {
  78             Self::Gated(ref stab, name, expl, _) => {
  79                 write!(fmt, "Gated({:?}, {}, {})", stab, name, expl)
  80             }
  81             Self::Ungated => write!(fmt, "Ungated"),
  82         }
  83     }
  84 }
  85
  86 impl AttributeGate {
  87     fn is_deprecated(&self) -> bool {
  88         matches!(*self, Self::Gated(Stability::Deprecated(_, _), ..))
  89     }
  90 }
  91
  92 /// A template that the attribute input must match.
  93 /// Only top-level shape (`#[attr]` vs `#[attr(...)]` vs `#[attr = ...]`) is considered now.
  94 #[derive(Clone, Copy, Default)]
  95 pub struct AttributeTemplate {
  96     pub word: bool,
  97     pub list: Option<&'static str>,
  98     pub name_value_str: Option<&'static str>,
  99 }
 100
 101 /// A convenience macro for constructing attribute templates.
 102 /// E.g., `template!(Word, List: "description")` means that the attribute
 103 /// supports forms `#[attr]` and `#[attr(description)]`.
 104 macro_rules! template {
 105     (Word) => { template!(@ true, None, None) };
 106     (List: $descr: expr) => { template!(@ false, Some($descr), None) };
 107     (NameValueStr: $descr: expr) => { template!(@ false, None, Some($descr)) };
 108     (Word, List: $descr: expr) => { template!(@ true, Some($descr), None) };
 109     (Word, NameValueStr: $descr: expr) => { template!(@ true, None, Some($descr)) };
 110     (List: $descr1: expr, NameValueStr: $descr2: expr) => {
 111         template!(@ false, Some($descr1), Some($descr2))
 112     };
 113     (Word, List: $descr1: expr, NameValueStr: $descr2: expr) => {
 114         template!(@ true, Some($descr1), Some($descr2))
 115     };
 116     (@ $word: expr, $list: expr, $name_value_str: expr) => { AttributeTemplate {
 117         word: $word, list: $list, name_value_str: $name_value_str
 118     } };
 119 }
 120
 121 macro_rules! ungated {
 122     ($attr:ident, $typ:expr, $tpl:expr $(,)?) => {
 123         (sym::$attr, $typ, $tpl, Ungated)
 124     };
 125 }
 126
 127 macro_rules! gated {
 128     ($attr:ident, $typ:expr, $tpl:expr, $gate:ident, $msg:expr $(,)?) => {
 129         (sym::$attr, $typ, $tpl, Gated(Stability::Unstable, sym::$gate, $msg, cfg_fn!($gate)))
 130     };
 131     ($attr:ident, $typ:expr, $tpl:expr, $msg:expr $(,)?) => {
 132         (sym::$attr, $typ, $tpl, Gated(Stability::Unstable, sym::$attr, $msg, cfg_fn!($attr)))
 133     };
 134 }
 135
 136 macro_rules! rustc_attr {
 137     (TEST, $attr:ident, $typ:expr, $tpl:expr $(,)?) => {
 138         rustc_attr!(
 139             $attr,
 140             $typ,
 141             $tpl,
 142             concat!(
 143                 "the `#[",
 144                 stringify!($attr),
 145                 "]` attribute is just used for rustc unit tests \
 146                 and will never be stable",
 147             ),
 148         )
 149     };
 150     ($attr:ident, $typ:expr, $tpl:expr, $msg:expr $(,)?) => {
 151         (
 152             sym::$attr,
 153             $typ,
 154             $tpl,
 155             Gated(Stability::Unstable, sym::rustc_attrs, $msg, cfg_fn!(rustc_attrs)),
 156         )
 157     };
 158 }
 159
 160 macro_rules! experimental {
 161     ($attr:ident) => {
 162         concat!("the `#[", stringify!($attr), "]` attribute is an experimental feature")
 163     };
 164 }
 165
 166 const IMPL_DETAIL: &str = "internal implementation detail";
 167 const INTERNAL_UNSTABLE: &str = "this is an internal attribute that will never be stable";
 168
 169 pub type BuiltinAttribute = (Symbol, AttributeType, AttributeTemplate, AttributeGate);
 170
 171 /// Attributes that have a special meaning to rustc or rustdoc.
 172 #[rustfmt::skip]
 173 pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
 174     // ==========================================================================
 175     // Stable attributes:
 176     // ==========================================================================
 177
 178     // Conditional compilation:
 179     ungated!(cfg, Normal, template!(List: "predicate")),
 180     ungated!(cfg_attr, Normal, template!(List: "predicate, attr1, attr2, ...")),
 181
 182     // Testing:
 183     ungated!(ignore, Normal, template!(Word, NameValueStr: "reason")),
 184     ungated!(
 185         should_panic, Normal,
 186         template!(Word, List: r#"expected = "reason"#, NameValueStr: "reason"),
 187     ),
 188     // FIXME(Centril): This can be used on stable but shouldn't.
 189     ungated!(reexport_test_harness_main, Normal, template!(NameValueStr: "name")),
 190
 191     // Macros:
 192     ungated!(automatically_derived, Normal, template!(Word)),
 193     // FIXME(#14407)
 194     ungated!(macro_use, Normal, template!(Word, List: "name1, name2, ...")),
 195     ungated!(macro_escape, Normal, template!(Word)), // Deprecated synonym for `macro_use`.
 196     ungated!(macro_export, Normal, template!(Word, List: "local_inner_macros")),
 197     ungated!(proc_macro, Normal, template!(Word)),
 198     ungated!(
 199         proc_macro_derive, Normal,
 200         template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)"),
 201     ),
 202     ungated!(proc_macro_attribute, Normal, template!(Word)),
 203
 204     // Lints:
 205     ungated!(warn, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
 206     ungated!(allow, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
 207     ungated!(forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
 208     ungated!(deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
 209     ungated!(must_use, AssumedUsed, template!(Word, NameValueStr: "reason")),
 210     // FIXME(#14407)
 211     ungated!(
 212         deprecated, Normal,
 213         template!(
 214             Word,
 215             List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#,
 216             NameValueStr: "reason"
 217         ),
 218     ),
 219
 220     // Crate properties:
 221     ungated!(crate_name, CrateLevel, template!(NameValueStr: "name")),
 222     ungated!(crate_type, CrateLevel, template!(NameValueStr: "bin|lib|...")),
 223     ungated!(crate_id, CrateLevel, template!(NameValueStr: "ignored")),
 224
 225     // ABI, linking, symbols, and FFI
 226     ungated!(
 227         link, AssumedUsed,
 228         template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...""#),
 229     ),
 230     ungated!(link_name, AssumedUsed, template!(NameValueStr: "name")),
 231     ungated!(no_link, AssumedUsed, template!(Word)),
 232     ungated!(repr, AssumedUsed, template!(List: "C")),
 233     ungated!(export_name, AssumedUsed, template!(NameValueStr: "name")),
 234     ungated!(link_section, AssumedUsed, template!(NameValueStr: "name")),
 235     ungated!(no_mangle, AssumedUsed, template!(Word)),
 236     ungated!(used, AssumedUsed, template!(Word)),
 237
 238     // Limits:
 239     ungated!(recursion_limit, CrateLevel, template!(NameValueStr: "N")),
 240     ungated!(type_length_limit, CrateLevel, template!(NameValueStr: "N")),
 241     gated!(
 242         const_eval_limit, CrateLevel, template!(NameValueStr: "N"), const_eval_limit,
 243         experimental!(const_eval_limit)
 244     ),
 245     gated!(
 246         move_size_limit, CrateLevel, template!(NameValueStr: "N"), large_assignments,
 247         experimental!(move_size_limit)
 248     ),
 249
 250     // Entry point:
 251     ungated!(main, Normal, template!(Word)),
 252     ungated!(start, Normal, template!(Word)),
 253     ungated!(no_start, CrateLevel, template!(Word)),
 254     ungated!(no_main, CrateLevel, template!(Word)),
 255
 256     // Modules, prelude, and resolution:
 257     ungated!(path, Normal, template!(NameValueStr: "file")),
 258     ungated!(no_std, CrateLevel, template!(Word)),
 259     ungated!(no_implicit_prelude, Normal, template!(Word)),
 260     ungated!(non_exhaustive, AssumedUsed, template!(Word)),
 261
 262     // Runtime
 263     ungated!(windows_subsystem, AssumedUsed, template!(NameValueStr: "windows|console")),
 264     ungated!(panic_handler, Normal, template!(Word)), // RFC 2070
 265
 266     // Code generation:
 267     ungated!(inline, AssumedUsed, template!(Word, List: "always|never")),
 268     ungated!(cold, AssumedUsed, template!(Word)),
 269     ungated!(no_builtins, AssumedUsed, template!(Word)),
 270     ungated!(target_feature, AssumedUsed, template!(List: r#"enable = "name""#)),
 271     ungated!(track_caller, AssumedUsed, template!(Word)),
 272     gated!(
 273         no_sanitize, AssumedUsed,
 274         template!(List: "address, memory, thread"),
 275         experimental!(no_sanitize)
 276     ),
 277     gated!(no_coverage, AssumedUsed, template!(Word), experimental!(no_coverage)),
 278
 279     // FIXME: #14408 assume docs are used since rustdoc looks at them.
 280     ungated!(doc, AssumedUsed, template!(List: "hidden|inline|...", NameValueStr: "string")),
 281
 282     // ==========================================================================
 283     // Unstable attributes:
 284     // ==========================================================================
 285
 286     // Linking:
 287     gated!(naked, AssumedUsed, template!(Word), naked_functions, experimental!(naked)),
 288     gated!(
 289         link_ordinal, AssumedUsed, template!(List: "ordinal"), raw_dylib,
 290         experimental!(link_ordinal)
 291     ),
 292
 293     // Plugins:
 294     (
 295         sym::plugin_registrar, Normal, template!(Word),
 296         Gated(
 297             Stability::Deprecated(
 298                 "https://github.com/rust-lang/rust/pull/64675",
 299                 Some("may be removed in a future compiler version"),
 300             ),
 301             sym::plugin_registrar,
 302             "compiler plugins are deprecated",
 303             cfg_fn!(plugin_registrar)
 304         )
 305     ),
 306     (
 307         sym::plugin, CrateLevel, template!(List: "name"),
 308         Gated(
 309             Stability::Deprecated(
 310                 "https://github.com/rust-lang/rust/pull/64675",
 311                 Some("may be removed in a future compiler version"),
 312             ),
 313             sym::plugin,
 314             "compiler plugins are deprecated",
 315             cfg_fn!(plugin)
 316         )
 317     ),
 318
 319     // Testing:
 320     gated!(allow_fail, Normal, template!(Word), experimental!(allow_fail)),
 321     gated!(
 322         test_runner, CrateLevel, template!(List: "path"), custom_test_frameworks,
 323         "custom test frameworks are an unstable feature",
 324     ),
 325     // RFC #1268
 326     gated!(marker, AssumedUsed, template!(Word), marker_trait_attr, experimental!(marker)),
 327     gated!(
 328         thread_local, AssumedUsed, template!(Word),
 329         "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
 330     ),
 331     gated!(no_core, CrateLevel, template!(Word), experimental!(no_core)),
 332     // RFC 2412
 333     gated!(
 334         optimize, AssumedUsed, template!(List: "size|speed"), optimize_attribute,
 335         experimental!(optimize),
 336     ),
 337     // RFC 2867
 338     gated!(instruction_set, AssumedUsed, template!(List: "set"), isa_attribute, experimental!(instruction_set)),
 339
 340     gated!(ffi_returns_twice, AssumedUsed, template!(Word), experimental!(ffi_returns_twice)),
 341     gated!(ffi_pure, AssumedUsed, template!(Word), experimental!(ffi_pure)),
 342     gated!(ffi_const, AssumedUsed, template!(Word), experimental!(ffi_const)),
 343     gated!(
 344         register_attr, CrateLevel, template!(List: "attr1, attr2, ..."),
 345         experimental!(register_attr),
 346     ),
 347     gated!(
 348         register_tool, CrateLevel, template!(List: "tool1, tool2, ..."),
 349         experimental!(register_tool),
 350     ),
 351
 352     gated!(cmse_nonsecure_entry, AssumedUsed, template!(Word), experimental!(cmse_nonsecure_entry)),
 353     // RFC 2632
 354     gated!(
 355         default_method_body_is_const, AssumedUsed, template!(Word), const_trait_impl,
 356         "`default_method_body_is_const` is a temporary placeholder for declaring default bodies \
 357         as `const`, which may be removed or renamed in the future."
 358     ),
 359
 360     // ==========================================================================
 361     // Internal attributes: Stability, deprecation, and unsafe:
 362     // ==========================================================================
 363
 364     ungated!(feature, CrateLevel, template!(List: "name1, name1, ...")),
 365     // FIXME(#14407) -- only looked at on-demand so we can't
 366     // guarantee they'll have already been checked.
 367     ungated!(
 368         rustc_deprecated, AssumedUsed,
 369         template!(List: r#"since = "version", reason = "...""#)
 370     ),
 371     // FIXME(#14407)
 372     ungated!(stable, AssumedUsed, template!(List: r#"feature = "name", since = "version""#)),
 373     // FIXME(#14407)
 374     ungated!(
 375         unstable, AssumedUsed,
 376         template!(List: r#"feature = "name", reason = "...", issue = "N""#),
 377     ),
 378     // FIXME(#14407)
 379     ungated!(rustc_const_unstable, AssumedUsed, template!(List: r#"feature = "name""#)),
 380     // FIXME(#14407)
 381     ungated!(rustc_const_stable, AssumedUsed, template!(List: r#"feature = "name""#)),
 382     gated!(
 383         allow_internal_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."),
 384         "allow_internal_unstable side-steps feature gating and stability checks",
 385     ),
 386     gated!(
 387         rustc_allow_const_fn_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."),
 388         "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
 389     ),
 390     gated!(
 391         allow_internal_unsafe, Normal, template!(Word),
 392         "allow_internal_unsafe side-steps the unsafe_code lint",
 393     ),
 394
 395     // ==========================================================================
 396     // Internal attributes: Type system related:
 397     // ==========================================================================
 398
 399     gated!(fundamental, AssumedUsed, template!(Word), experimental!(fundamental)),
 400     gated!(
 401         may_dangle, Normal, template!(Word), dropck_eyepatch,
 402         "`may_dangle` has unstable semantics and may be removed in the future",
 403     ),
 404
 405     // ==========================================================================
 406     // Internal attributes: Runtime related:
 407     // ==========================================================================
 408
 409     rustc_attr!(rustc_allocator, AssumedUsed, template!(Word), IMPL_DETAIL),
 410     rustc_attr!(rustc_allocator_nounwind, AssumedUsed, template!(Word), IMPL_DETAIL),
 411     gated!(alloc_error_handler, Normal, template!(Word), experimental!(alloc_error_handler)),
 412     gated!(
 413         default_lib_allocator, AssumedUsed, template!(Word), allocator_internals,
 414         experimental!(default_lib_allocator),
 415     ),
 416     gated!(
 417         needs_allocator, Normal, template!(Word), allocator_internals,
 418         experimental!(needs_allocator),
 419     ),
 420     gated!(panic_runtime, AssumedUsed, template!(Word), experimental!(panic_runtime)),
 421     gated!(needs_panic_runtime, AssumedUsed, template!(Word), experimental!(needs_panic_runtime)),
 422     gated!(
 423         unwind, AssumedUsed, template!(List: "allowed|aborts"), unwind_attributes,
 424         experimental!(unwind),
 425     ),
 426     gated!(
 427         compiler_builtins, AssumedUsed, template!(Word),
 428         "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \
 429         which contains compiler-rt intrinsics and will never be stable",
 430     ),
 431     gated!(
 432         profiler_runtime, AssumedUsed, template!(Word),
 433         "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \
 434         which contains the profiler runtime and will never be stable",
 435     ),
 436
 437     // ==========================================================================
 438     // Internal attributes, Linkage:
 439     // ==========================================================================
 440
 441     gated!(
 442         linkage, AssumedUsed, template!(NameValueStr: "external|internal|..."),
 443         "the `linkage` attribute is experimental and not portable across platforms",
 444     ),
 445     rustc_attr!(rustc_std_internal_symbol, AssumedUsed, template!(Word), INTERNAL_UNSTABLE),
 446
 447     // ==========================================================================
 448     // Internal attributes, Macro related:
 449     // ==========================================================================
 450
 451     rustc_attr!(
 452         rustc_builtin_macro, AssumedUsed,
 453         template!(Word, List: "name, /*opt*/ attributes(name1, name2, ...)"),
 454         IMPL_DETAIL,
 455     ),
 456     rustc_attr!(rustc_proc_macro_decls, Normal, template!(Word), INTERNAL_UNSTABLE),
 457     rustc_attr!(
 458         rustc_macro_transparency, AssumedUsed,
 459         template!(NameValueStr: "transparent|semitransparent|opaque"),
 460         "used internally for testing macro hygiene",
 461     ),
 462
 463     // ==========================================================================
 464     // Internal attributes, Diagnostics related:
 465     // ==========================================================================
 466
 467     rustc_attr!(
 468         rustc_on_unimplemented, AssumedUsed,
 469         template!(
 470             List: r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#,
 471             NameValueStr: "message"
 472         ),
 473         INTERNAL_UNSTABLE
 474     ),
 475     // Enumerates "identity-like" conversion methods to suggest on type mismatch.
 476     rustc_attr!(rustc_conversion_suggestion, AssumedUsed, template!(Word), INTERNAL_UNSTABLE),
 477
 478     // ==========================================================================
 479     // Internal attributes, Const related:
 480     // ==========================================================================
 481
 482     rustc_attr!(rustc_promotable, AssumedUsed, template!(Word), IMPL_DETAIL),
 483     rustc_attr!(rustc_legacy_const_generics, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE),
 484
 485     // ==========================================================================
 486     // Internal attributes, Layout related:
 487     // ==========================================================================
 488
 489     rustc_attr!(
 490         rustc_layout_scalar_valid_range_start, AssumedUsed, template!(List: "value"),
 491         "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
 492         niche optimizations in libcore and will never be stable",
 493     ),
 494     rustc_attr!(
 495         rustc_layout_scalar_valid_range_end, AssumedUsed, template!(List: "value"),
 496         "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
 497         niche optimizations in libcore and will never be stable",
 498     ),
 499     rustc_attr!(
 500         rustc_nonnull_optimization_guaranteed, AssumedUsed, template!(Word),
 501         "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable \
 502         niche optimizations in libcore and will never be stable",
 503     ),
 504
 505     // ==========================================================================
 506     // Internal attributes, Misc:
 507     // ==========================================================================
 508     gated!(
 509         lang, Normal, template!(NameValueStr: "name"), lang_items,
 510         "language items are subject to change",
 511     ),
 512     (
 513         sym::rustc_diagnostic_item,
 514         Normal,
 515         template!(NameValueStr: "name"),
 516         Gated(
 517             Stability::Unstable,
 518             sym::rustc_attrs,
 519             "diagnostic items compiler internal support for linting",
 520             cfg_fn!(rustc_attrs),
 521         ),
 522     ),
 523     gated!(
 524         // Used in resolve:
 525         prelude_import, AssumedUsed, template!(Word),
 526         "`#[prelude_import]` is for use by rustc only",
 527     ),
 528     gated!(
 529         rustc_paren_sugar, Normal, template!(Word), unboxed_closures,
 530         "unboxed_closures are still evolving",
 531     ),
 532     rustc_attr!(
 533         rustc_inherit_overflow_checks, AssumedUsed, template!(Word),
 534         "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \
 535         overflow checking behavior of several libcore functions that are inlined \
 536         across crates and will never be stable",
 537     ),
 538     rustc_attr!(rustc_reservation_impl, Normal, template!(NameValueStr: "reservation message"),
 539                 "the `#[rustc_reservation_impl]` attribute is internally used \
 540                  for reserving for `for<T> From<!> for T` impl"
 541     ),
 542     rustc_attr!(
 543         rustc_test_marker, Normal, template!(Word),
 544         "the `#[rustc_test_marker]` attribute is used internally to track tests",
 545     ),
 546     rustc_attr!(
 547         rustc_unsafe_specialization_marker, Normal, template!(Word),
 548         "the `#[rustc_unsafe_specialization_marker]` attribute is used to check specializations"
 549     ),
 550     rustc_attr!(
 551         rustc_specialization_trait, Normal, template!(Word),
 552         "the `#[rustc_specialization_trait]` attribute is used to check specializations"
 553     ),
 554     rustc_attr!(
 555         rustc_main, Normal, template!(Word),
 556         "the `#[rustc_main]` attribute is used internally to specify test entry point function",
 557     ),
 558     rustc_attr!(
 559         rustc_skip_array_during_method_dispatch, Normal, template!(Word),
 560         "the `#[rustc_skip_array_during_method_dispatch]` attribute is used to exclude a trait \
 561         from method dispatch when the receiver is an array, for compatibility in editions < 2021."
 562     ),
 563
 564     // ==========================================================================
 565     // Internal attributes, Testing:
 566     // ==========================================================================
 567
 568     rustc_attr!(TEST, rustc_outlives, Normal, template!(Word)),
 569     rustc_attr!(TEST, rustc_capture_analysis, Normal, template!(Word)),
 570     rustc_attr!(TEST, rustc_insignificant_dtor, Normal, template!(Word)),
 571     rustc_attr!(TEST, rustc_variance, Normal, template!(Word)),
 572     rustc_attr!(TEST, rustc_layout, Normal, template!(List: "field1, field2, ...")),
 573     rustc_attr!(TEST, rustc_regions, Normal, template!(Word)),
 574     rustc_attr!(
 575         TEST, rustc_error, AssumedUsed,
 576         template!(Word, List: "delay_span_bug_from_inside_query")
 577     ),
 578     rustc_attr!(TEST, rustc_dump_user_substs, AssumedUsed, template!(Word)),
 579     rustc_attr!(TEST, rustc_evaluate_where_clauses, AssumedUsed, template!(Word)),
 580     rustc_attr!(TEST, rustc_if_this_changed, AssumedUsed, template!(Word, List: "DepNode")),
 581     rustc_attr!(TEST, rustc_then_this_would_need, AssumedUsed, template!(List: "DepNode")),
 582     rustc_attr!(
 583         TEST, rustc_clean, AssumedUsed,
 584         template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
 585     ),
 586     rustc_attr!(
 587         TEST, rustc_partition_reused, AssumedUsed,
 588         template!(List: r#"cfg = "...", module = "...""#),
 589     ),
 590     rustc_attr!(
 591         TEST, rustc_partition_codegened, AssumedUsed,
 592         template!(List: r#"cfg = "...", module = "...""#),
 593     ),
 594     rustc_attr!(
 595         TEST, rustc_expected_cgu_reuse, AssumedUsed,
 596         template!(List: r#"cfg = "...", module = "...", kind = "...""#),
 597     ),
 598     rustc_attr!(TEST, rustc_synthetic, AssumedUsed, template!(Word)),
 599     rustc_attr!(TEST, rustc_symbol_name, AssumedUsed, template!(Word)),
 600     rustc_attr!(TEST, rustc_polymorphize_error, AssumedUsed, template!(Word)),
 601     rustc_attr!(TEST, rustc_def_path, AssumedUsed, template!(Word)),
 602     rustc_attr!(TEST, rustc_mir, AssumedUsed, template!(List: "arg1, arg2, ...")),
 603     rustc_attr!(TEST, rustc_dump_program_clauses, AssumedUsed, template!(Word)),
 604     rustc_attr!(TEST, rustc_dump_env_program_clauses, AssumedUsed, template!(Word)),
 605     rustc_attr!(TEST, rustc_object_lifetime_default, AssumedUsed, template!(Word)),
 606     rustc_attr!(TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/)),
 607     gated!(
 608         omit_gdb_pretty_printer_section, AssumedUsed, template!(Word),
 609         "the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite",
 610     ),
 611 ];
 612
 613 pub fn deprecated_attributes() -> Vec<&'static BuiltinAttribute> {
 614     BUILTIN_ATTRIBUTES.iter().filter(|(.., gate)| gate.is_deprecated()).collect()
 615 }
 616
 617 pub fn is_builtin_attr_name(name: Symbol) -> bool {
 618     BUILTIN_ATTRIBUTE_MAP.get(&name).is_some()
 619 }
 620
 621 pub static BUILTIN_ATTRIBUTE_MAP: SyncLazy<FxHashMap<Symbol, &BuiltinAttribute>> =
 622     SyncLazy::new(|| {
 623         let mut map = FxHashMap::default();
 624         for attr in BUILTIN_ATTRIBUTES.iter() {
 625             if map.insert(attr.0, attr).is_some() {
 626                 panic!("duplicate builtin attribute `{}`", attr.0);
 627             }
 628         }
 629         map
 630     });