rustc_feature/unstable.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656
//! List of the unstable feature gates.
use rustc_data_structures::fx::FxHashSet;
use rustc_span::Span;
use rustc_span::symbol::{Symbol, sym};
use super::{Feature, to_nonzero};
#[derive(PartialEq)]
enum FeatureStatus {
Default,
Incomplete,
Internal,
}
macro_rules! status_to_enum {
(unstable) => {
FeatureStatus::Default
};
(incomplete) => {
FeatureStatus::Incomplete
};
(internal) => {
FeatureStatus::Internal
};
}
/// A set of features to be used by later passes.
///
/// There are two ways to check if a language feature `foo` is enabled:
/// - Directly with the `foo` method, e.g. `if tcx.features().foo() { ... }`.
/// - With the `enabled` method, e.g. `if tcx.features.enabled(sym::foo) { ... }`.
///
/// The former is preferred. `enabled` should only be used when the feature symbol is not a
/// constant, e.g. a parameter, or when the feature is a library feature.
#[derive(Clone, Default, Debug)]
pub struct Features {
/// `#![feature]` attrs for language features, for error reporting.
enabled_lang_features: Vec<EnabledLangFeature>,
/// `#![feature]` attrs for non-language (library) features.
enabled_lib_features: Vec<EnabledLibFeature>,
/// `enabled_lang_features` + `enabled_lib_features`.
enabled_features: FxHashSet<Symbol>,
}
/// Information about an enabled language feature.
#[derive(Debug, Copy, Clone)]
pub struct EnabledLangFeature {
/// Name of the feature gate guarding the language feature.
pub gate_name: Symbol,
/// Span of the `#[feature(...)]` attribute.
pub attr_sp: Span,
/// If the lang feature is stable, the version number when it was stabilized.
pub stable_since: Option<Symbol>,
}
/// Information abhout an enabled library feature.
#[derive(Debug, Copy, Clone)]
pub struct EnabledLibFeature {
pub gate_name: Symbol,
pub attr_sp: Span,
}
impl Features {
/// `since` should be set for stable features that are nevertheless enabled with a `#[feature]`
/// attribute, indicating since when they are stable.
pub fn set_enabled_lang_feature(&mut self, lang_feat: EnabledLangFeature) {
self.enabled_lang_features.push(lang_feat);
self.enabled_features.insert(lang_feat.gate_name);
}
pub fn set_enabled_lib_feature(&mut self, lib_feat: EnabledLibFeature) {
self.enabled_lib_features.push(lib_feat);
self.enabled_features.insert(lib_feat.gate_name);
}
/// Returns a list of [`EnabledLangFeature`] with info about:
///
/// - Feature gate name.
/// - The span of the `#[feature]` attribute.
/// - For stable language features, version info for when it was stabilized.
pub fn enabled_lang_features(&self) -> &Vec<EnabledLangFeature> {
&self.enabled_lang_features
}
pub fn enabled_lib_features(&self) -> &Vec<EnabledLibFeature> {
&self.enabled_lib_features
}
pub fn enabled_features(&self) -> &FxHashSet<Symbol> {
&self.enabled_features
}
/// Is the given feature enabled (via `#[feature(...)]`)?
pub fn enabled(&self, feature: Symbol) -> bool {
self.enabled_features.contains(&feature)
}
}
macro_rules! declare_features {
($(
$(#[doc = $doc:tt])* ($status:ident, $feature:ident, $ver:expr, $issue:expr),
)+) => {
/// Unstable language features that are being implemented or being
/// considered for acceptance (stabilization) or removal.
pub const UNSTABLE_LANG_FEATURES: &[Feature] = &[
$(Feature {
name: sym::$feature,
since: $ver,
issue: to_nonzero($issue),
}),+
];
impl Features {
$(
pub fn $feature(&self) -> bool {
self.enabled_features.contains(&sym::$feature)
}
)*
/// Some features are known to be incomplete and using them is likely to have
/// unanticipated results, such as compiler crashes. We warn the user about these
/// to alert them.
pub fn incomplete(&self, feature: Symbol) -> bool {
match feature {
$(
sym::$feature => status_to_enum!($status) == FeatureStatus::Incomplete,
)*
_ if self.enabled_features.contains(&feature) => {
// Accepted/removed features and library features aren't in this file but
// are never incomplete.
false
}
_ => panic!("`{}` was not listed in `declare_features`", feature),
}
}
/// Some features are internal to the compiler and standard library and should not
/// be used in normal projects. We warn the user about these to alert them.
pub fn internal(&self, feature: Symbol) -> bool {
match feature {
$(
sym::$feature => status_to_enum!($status) == FeatureStatus::Internal,
)*
_ if self.enabled_features.contains(&feature) => {
// This could be accepted/removed, or a libs feature.
// Accepted/removed features aren't in this file but are never internal
// (a removed feature might have been internal, but that's now irrelevant).
// Libs features are internal if they end in `_internal` or `_internals`.
// As a special exception we also consider `core_intrinsics` internal;
// renaming that age-old feature is just not worth the hassle.
// We just always test the name; it's not a big deal if we accidentally hit
// an accepted/removed lang feature that way.
let name = feature.as_str();
name == "core_intrinsics" || name.ends_with("_internal") || name.ends_with("_internals")
}
_ => panic!("`{}` was not listed in `declare_features`", feature),
}
}
}
};
}
// See https://rustc-dev-guide.rust-lang.org/feature-gates.html#feature-gates for more
// documentation about handling feature gates.
//
// If you change this, please modify `src/doc/unstable-book` as well.
//
// Don't ever remove anything from this list; move them to `accepted.rs` if
// accepted or `removed.rs` if removed.
//
// The version numbers here correspond to the version in which the current status
// was set.
//
// Note that the features are grouped into internal/user-facing and then
// sorted alphabetically inside those groups. This is enforced with tidy.
//
// N.B., `tools/tidy/src/features.rs` parses this information directly out of the
// source, so take care when modifying it.
#[rustfmt::skip]
declare_features! (
// -------------------------------------------------------------------------
// feature-group-start: internal feature gates (no tracking issue)
// -------------------------------------------------------------------------
// no-tracking-issue-start
/// Allows using the `unadjusted` ABI; perma-unstable.
(internal, abi_unadjusted, "1.16.0", None),
/// Allows using `#![needs_allocator]`, an implementation detail of `#[global_allocator]`.
(internal, allocator_internals, "1.20.0", None),
/// Allows using `#[allow_internal_unsafe]`. This is an
/// attribute on `macro_rules!` and can't use the attribute handling
/// below (it has to be checked before expansion possibly makes
/// macros disappear).
(internal, allow_internal_unsafe, "1.0.0", None),
/// Allows using `#[allow_internal_unstable]`. This is an
/// attribute on `macro_rules!` and can't use the attribute handling
/// below (it has to be checked before expansion possibly makes
/// macros disappear).
(internal, allow_internal_unstable, "1.0.0", None),
/// Allows using anonymous lifetimes in argument-position impl-trait.
(unstable, anonymous_lifetime_in_impl_trait, "1.63.0", None),
/// Allows identifying the `compiler_builtins` crate.
(internal, compiler_builtins, "1.13.0", None),
/// Allows writing custom MIR
(internal, custom_mir, "1.65.0", None),
/// Outputs useful `assert!` messages
(unstable, generic_assert, "1.63.0", None),
/// Allows using the `rust-intrinsic`'s "ABI".
(internal, intrinsics, "1.0.0", None),
/// Allows using `#[lang = ".."]` attribute for linking items to special compiler logic.
(internal, lang_items, "1.0.0", None),
/// Changes `impl Trait` to capture all lifetimes in scope.
(unstable, lifetime_capture_rules_2024, "1.76.0", None),
/// Allows `#[link(..., cfg(..))]`; perma-unstable per #37406
(internal, link_cfg, "1.14.0", None),
/// Allows using `?Trait` trait bounds in more contexts.
(internal, more_maybe_bounds, "1.82.0", None),
/// Allows the `multiple_supertrait_upcastable` lint.
(unstable, multiple_supertrait_upcastable, "1.69.0", None),
/// Allow negative trait bounds. This is an internal-only feature for testing the trait solver!
(internal, negative_bounds, "1.71.0", None),
/// Allows using `#[omit_gdb_pretty_printer_section]`.
(internal, omit_gdb_pretty_printer_section, "1.5.0", None),
/// Set the maximum pattern complexity allowed (not limited by default).
(internal, pattern_complexity, "1.78.0", None),
/// Allows using pattern types.
(internal, pattern_types, "1.79.0", Some(123646)),
/// Allows using `#[prelude_import]` on glob `use` items.
(internal, prelude_import, "1.2.0", None),
/// Used to identify crates that contain the profiler runtime.
(internal, profiler_runtime, "1.18.0", None),
/// Allows using `rustc_*` attributes (RFC 572).
(internal, rustc_attrs, "1.0.0", None),
/// Allows using the `#[stable]` and `#[unstable]` attributes.
(internal, staged_api, "1.0.0", None),
/// Added for testing unstable lints; perma-unstable.
(internal, test_unstable_lint, "1.60.0", None),
/// Helps with formatting for `group_imports = "StdExternalCrate"`.
(unstable, unqualified_local_imports, "1.83.0", None),
/// Use for stable + negative coherence and strict coherence depending on trait's
/// rustc_strict_coherence value.
(unstable, with_negative_coherence, "1.60.0", None),
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// Features are listed in alphabetical order. Tidy will fail if you don't keep it this way.
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// no-tracking-issue-end
// -------------------------------------------------------------------------
// feature-group-end: internal feature gates (no tracking issue)
// -------------------------------------------------------------------------
// -------------------------------------------------------------------------
// feature-group-start: internal feature gates
// -------------------------------------------------------------------------
/// Allows using the `vectorcall` ABI.
(unstable, abi_vectorcall, "1.7.0", Some(124485)),
/// Allows features specific to auto traits.
/// Renamed from `optin_builtin_traits`.
(unstable, auto_traits, "1.50.0", Some(13231)),
/// Allows using `box` in patterns (RFC 469).
(unstable, box_patterns, "1.0.0", Some(29641)),
/// Allows builtin # foo() syntax
(internal, builtin_syntax, "1.71.0", Some(110680)),
/// Allows `#[doc(notable_trait)]`.
/// Renamed from `doc_spotlight`.
(unstable, doc_notable_trait, "1.52.0", Some(45040)),
/// Allows using the `may_dangle` attribute (RFC 1327).
(unstable, dropck_eyepatch, "1.10.0", Some(34761)),
/// Allows making `dyn Trait` well-formed even if `Trait` is not dyn-compatible[^1].
/// In that case, `dyn Trait: Trait` does not hold. Moreover, coercions and
/// casts in safe Rust to `dyn Trait` for such a `Trait` is also forbidden.
///
/// Renamed from `object_safe_for_dispatch`.
///
/// [^1]: Formerly known as "object safe".
(unstable, dyn_compatible_for_dispatch, "1.83.0", Some(43561)),
/// Allows using the `#[fundamental]` attribute.
(unstable, fundamental, "1.0.0", Some(29635)),
/// Allows using `#[link_name="llvm.*"]`.
(internal, link_llvm_intrinsics, "1.0.0", Some(29602)),
/// Allows using the `#[linkage = ".."]` attribute.
(unstable, linkage, "1.0.0", Some(29603)),
/// Allows declaring with `#![needs_panic_runtime]` that a panic runtime is needed.
(internal, needs_panic_runtime, "1.10.0", Some(32837)),
/// Allows using the `#![panic_runtime]` attribute.
(internal, panic_runtime, "1.10.0", Some(32837)),
/// Allows using `#[rustc_allow_const_fn_unstable]`.
/// This is an attribute on `const fn` for the same
/// purpose as `#[allow_internal_unstable]`.
(internal, rustc_allow_const_fn_unstable, "1.49.0", Some(69399)),
/// Allows using compiler's own crates.
(unstable, rustc_private, "1.0.0", Some(27812)),
/// Allows using internal rustdoc features like `doc(keyword)`.
(internal, rustdoc_internals, "1.58.0", Some(90418)),
/// Allows using the `rustdoc::missing_doc_code_examples` lint
(unstable, rustdoc_missing_doc_code_examples, "1.31.0", Some(101730)),
/// Allows using `#[start]` on a function indicating that it is the program entrypoint.
(unstable, start, "1.0.0", Some(29633)),
/// Allows using `#[structural_match]` which indicates that a type is structurally matchable.
/// FIXME: Subsumed by trait `StructuralPartialEq`, cannot move to removed until a library
/// feature with the same name exists.
(unstable, structural_match, "1.8.0", Some(31434)),
/// Allows using the `rust-call` ABI.
(unstable, unboxed_closures, "1.0.0", Some(29625)),
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// Features are listed in alphabetical order. Tidy will fail if you don't keep it this way.
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// -------------------------------------------------------------------------
// feature-group-end: internal feature gates
// -------------------------------------------------------------------------
// -------------------------------------------------------------------------
// feature-group-start: actual feature gates (target features)
// -------------------------------------------------------------------------
// FIXME: Document these and merge with the list below.
// Unstable `#[target_feature]` directives.
(unstable, aarch64_unstable_target_feature, "1.82.0", Some(44839)),
(unstable, aarch64_ver_target_feature, "1.27.0", Some(44839)),
(unstable, arm_target_feature, "1.27.0", Some(44839)),
(unstable, avx512_target_feature, "1.27.0", Some(44839)),
(unstable, bpf_target_feature, "1.54.0", Some(44839)),
(unstable, csky_target_feature, "1.73.0", Some(44839)),
(unstable, ermsb_target_feature, "1.49.0", Some(44839)),
(unstable, hexagon_target_feature, "1.27.0", Some(44839)),
(unstable, lahfsahf_target_feature, "1.78.0", Some(44839)),
(unstable, loongarch_target_feature, "1.73.0", Some(44839)),
(unstable, mips_target_feature, "1.27.0", Some(44839)),
(unstable, powerpc_target_feature, "1.27.0", Some(44839)),
(unstable, prfchw_target_feature, "1.78.0", Some(44839)),
(unstable, riscv_target_feature, "1.45.0", Some(44839)),
(unstable, rtm_target_feature, "1.35.0", Some(44839)),
(unstable, s390x_target_feature, "1.82.0", Some(44839)),
(unstable, sse4a_target_feature, "1.27.0", Some(44839)),
(unstable, tbm_target_feature, "1.27.0", Some(44839)),
(unstable, wasm_target_feature, "1.30.0", Some(44839)),
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// Features are listed in alphabetical order. Tidy will fail if you don't keep it this way.
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// -------------------------------------------------------------------------
// feature-group-end: actual feature gates (target features)
// -------------------------------------------------------------------------
// -------------------------------------------------------------------------
// feature-group-start: actual feature gates
// -------------------------------------------------------------------------
/// Allows `extern "avr-interrupt" fn()` and `extern "avr-non-blocking-interrupt" fn()`.
(unstable, abi_avr_interrupt, "1.45.0", Some(69664)),
/// Allows `extern "C-cmse-nonsecure-call" fn()`.
(unstable, abi_c_cmse_nonsecure_call, "1.51.0", Some(81391)),
/// Allows `extern "msp430-interrupt" fn()`.
(unstable, abi_msp430_interrupt, "1.16.0", Some(38487)),
/// Allows `extern "ptx-*" fn()`.
(unstable, abi_ptx, "1.15.0", Some(38788)),
/// Allows `extern "riscv-interrupt-m" fn()` and `extern "riscv-interrupt-s" fn()`.
(unstable, abi_riscv_interrupt, "1.73.0", Some(111889)),
/// Allows `extern "x86-interrupt" fn()`.
(unstable, abi_x86_interrupt, "1.17.0", Some(40180)),
/// Allows additional const parameter types, such as `[u8; 10]` or user defined types
(unstable, adt_const_params, "1.56.0", Some(95174)),
/// Allows defining an `#[alloc_error_handler]`.
(unstable, alloc_error_handler, "1.29.0", Some(51540)),
/// Allows inherent and trait methods with arbitrary self types.
(unstable, arbitrary_self_types, "1.23.0", Some(44874)),
/// Allows inherent and trait methods with arbitrary self types that are raw pointers.
(unstable, arbitrary_self_types_pointers, "1.83.0", Some(44874)),
/// Enables experimental inline assembly support for additional architectures.
(unstable, asm_experimental_arch, "1.58.0", Some(93335)),
/// Allows using `label` operands in inline assembly.
(unstable, asm_goto, "1.78.0", Some(119364)),
/// Allows the `may_unwind` option in inline assembly.
(unstable, asm_unwind, "1.58.0", Some(93334)),
/// Allows users to enforce equality of associated constants `TraitImpl<AssocConst=3>`.
(unstable, associated_const_equality, "1.58.0", Some(92827)),
/// Allows associated type defaults.
(unstable, associated_type_defaults, "1.2.0", Some(29661)),
/// Allows `async || body` closures.
(unstable, async_closure, "1.37.0", Some(62290)),
/// Allows `#[track_caller]` on async functions.
(unstable, async_fn_track_caller, "1.73.0", Some(110011)),
/// Allows `for await` loops.
(unstable, async_for_loop, "1.77.0", Some(118898)),
/// Allows using C-variadics.
(unstable, c_variadic, "1.34.0", Some(44930)),
/// Allows the use of `#[cfg(<true/false>)]`.
(unstable, cfg_boolean_literals, "1.83.0", Some(131204)),
/// Allows the use of `#[cfg(overflow_checks)` to check if integer overflow behaviour.
(unstable, cfg_overflow_checks, "1.71.0", Some(111466)),
/// Provides the relocation model information as cfg entry
(unstable, cfg_relocation_model, "1.73.0", Some(114929)),
/// Allows the use of `#[cfg(sanitize = "option")]`; set when -Zsanitizer is used.
(unstable, cfg_sanitize, "1.41.0", Some(39699)),
/// Allows `cfg(sanitizer_cfi_generalize_pointers)` and `cfg(sanitizer_cfi_normalize_integers)`.
(unstable, cfg_sanitizer_cfi, "1.77.0", Some(89653)),
/// Allows `cfg(target(abi = "..."))`.
(unstable, cfg_target_compact, "1.63.0", Some(96901)),
/// Allows `cfg(target_has_atomic_load_store = "...")`.
(unstable, cfg_target_has_atomic, "1.60.0", Some(94039)),
/// Allows `cfg(target_has_atomic_equal_alignment = "...")`.
(unstable, cfg_target_has_atomic_equal_alignment, "1.60.0", Some(93822)),
/// Allows `cfg(target_thread_local)`.
(unstable, cfg_target_thread_local, "1.7.0", Some(29594)),
/// Allows the use of `#[cfg(ub_checks)` to check if UB checks are enabled.
(unstable, cfg_ub_checks, "1.79.0", Some(123499)),
/// Allow conditional compilation depending on rust version
(unstable, cfg_version, "1.45.0", Some(64796)),
/// Allows to use the `#[cfi_encoding = ""]` attribute.
(unstable, cfi_encoding, "1.71.0", Some(89653)),
/// Allows `for<...>` on closures and coroutines.
(unstable, closure_lifetime_binder, "1.64.0", Some(97362)),
/// Allows `#[track_caller]` on closures and coroutines.
(unstable, closure_track_caller, "1.57.0", Some(87417)),
/// Allows `extern "C-cmse-nonsecure-entry" fn()`.
(unstable, cmse_nonsecure_entry, "1.48.0", Some(75835)),
/// Allows `async {}` expressions in const contexts.
(unstable, const_async_blocks, "1.53.0", Some(85368)),
/// Allows `const || {}` closures in const contexts.
(incomplete, const_closures, "1.68.0", Some(106003)),
/// Allows `for _ in _` loops in const contexts.
(unstable, const_for, "1.56.0", Some(87575)),
/// Be more precise when looking for live drops in a const context.
(unstable, const_precise_live_drops, "1.46.0", Some(73255)),
/// Allows `impl const Trait for T` syntax.
(unstable, const_trait_impl, "1.42.0", Some(67792)),
/// Allows the `?` operator in const contexts.
(unstable, const_try, "1.56.0", Some(74935)),
/// Allows coroutines to be cloned.
(unstable, coroutine_clone, "1.65.0", Some(95360)),
/// Allows defining coroutines.
(unstable, coroutines, "1.21.0", Some(43122)),
/// Allows function attribute `#[coverage(on/off)]`, to control coverage
/// instrumentation of that function.
(unstable, coverage_attribute, "1.74.0", Some(84605)),
/// Allows non-builtin attributes in inner attribute position.
(unstable, custom_inner_attributes, "1.30.0", Some(54726)),
/// Allows custom test frameworks with `#![test_runner]` and `#[test_case]`.
(unstable, custom_test_frameworks, "1.30.0", Some(50297)),
/// Allows declarative macros 2.0 (`macro`).
(unstable, decl_macro, "1.17.0", Some(39412)),
/// Allows using `#[deprecated_safe]` to deprecate the safeness of a function or trait
(unstable, deprecated_safe, "1.61.0", Some(94978)),
/// Allows having using `suggestion` in the `#[deprecated]` attribute.
(unstable, deprecated_suggestion, "1.61.0", Some(94785)),
/// Allows deref patterns.
(incomplete, deref_patterns, "1.79.0", Some(87121)),
/// Controls errors in trait implementations.
(unstable, do_not_recommend, "1.67.0", Some(51992)),
/// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.
(unstable, doc_auto_cfg, "1.58.0", Some(43781)),
/// Allows `#[doc(cfg(...))]`.
(unstable, doc_cfg, "1.21.0", Some(43781)),
/// Allows `#[doc(cfg_hide(...))]`.
(unstable, doc_cfg_hide, "1.57.0", Some(43781)),
/// Allows `#[doc(masked)]`.
(unstable, doc_masked, "1.21.0", Some(44027)),
/// Allows `dyn* Trait` objects.
(incomplete, dyn_star, "1.65.0", Some(102425)),
/// Allows exhaustive pattern matching on types that contain uninhabited types.
(unstable, exhaustive_patterns, "1.13.0", Some(51085)),
/// Allows explicit tail calls via `become` expression.
(incomplete, explicit_tail_calls, "1.72.0", Some(112788)),
/// Allows using `efiapi`, `sysv64` and `win64` as calling convention
/// for functions with varargs.
(unstable, extended_varargs_abi_support, "1.65.0", Some(100189)),
/// Allows defining `extern type`s.
(unstable, extern_types, "1.23.0", Some(43467)),
/// Allow using 128-bit (quad precision) floating point numbers.
(unstable, f128, "1.78.0", Some(116909)),
/// Allow using 16-bit (half precision) floating point numbers.
(unstable, f16, "1.78.0", Some(116909)),
/// Allows the use of `#[ffi_const]` on foreign functions.
(unstable, ffi_const, "1.45.0", Some(58328)),
/// Allows the use of `#[ffi_pure]` on foreign functions.
(unstable, ffi_pure, "1.45.0", Some(58329)),
/// Controlling the behavior of fmt::Debug
(unstable, fmt_debug, "1.82.0", Some(129709)),
/// Allows using `#[repr(align(...))]` on function items
(unstable, fn_align, "1.53.0", Some(82232)),
/// Support delegating implementation of functions to other already implemented functions.
(incomplete, fn_delegation, "1.76.0", Some(118212)),
/// Allows impls for the Freeze trait.
(internal, freeze_impls, "1.78.0", Some(121675)),
/// Allows defining gen blocks and `gen fn`.
(unstable, gen_blocks, "1.75.0", Some(117078)),
/// Infer generic args for both consts and types.
(unstable, generic_arg_infer, "1.55.0", Some(85077)),
/// An extension to the `generic_associated_types` feature, allowing incomplete features.
(incomplete, generic_associated_types_extended, "1.61.0", Some(95451)),
/// Allows non-trivial generic constants which have to have wfness manually propagated to callers
(incomplete, generic_const_exprs, "1.56.0", Some(76560)),
/// Allows generic parameters and where-clauses on free & associated const items.
(incomplete, generic_const_items, "1.73.0", Some(113521)),
/// Allows registering static items globally, possibly across crates, to iterate over at runtime.
(unstable, global_registration, "1.80.0", Some(125119)),
/// Allows using `..=X` as a patterns in slices.
(unstable, half_open_range_patterns_in_slices, "1.66.0", Some(67264)),
/// Allows `if let` guard in match arms.
(unstable, if_let_guard, "1.47.0", Some(51114)),
/// Allows `impl Trait` to be used inside associated types (RFC 2515).
(unstable, impl_trait_in_assoc_type, "1.70.0", Some(63063)),
/// Allows `impl Trait` as output type in `Fn` traits in return position of functions.
(unstable, impl_trait_in_fn_trait_return, "1.64.0", Some(99697)),
/// Allows associated types in inherent impls.
(incomplete, inherent_associated_types, "1.52.0", Some(8995)),
/// Allow anonymous constants from an inline `const` block in pattern position
(unstable, inline_const_pat, "1.58.0", Some(76001)),
/// Allows using `pointer` and `reference` in intra-doc links
(unstable, intra_doc_pointers, "1.51.0", Some(80896)),
// Allows setting the threshold for the `large_assignments` lint.
(unstable, large_assignments, "1.52.0", Some(83518)),
/// Allow to have type alias types for inter-crate use.
(incomplete, lazy_type_alias, "1.72.0", Some(112792)),
/// Allows `if/while p && let q = r && ...` chains.
(unstable, let_chains, "1.37.0", Some(53667)),
/// Allows using `#[link(kind = "link-arg", name = "...")]`
/// to pass custom arguments to the linker.
(unstable, link_arg_attribute, "1.76.0", Some(99427)),
/// Give access to additional metadata about declarative macro meta-variables.
(unstable, macro_metavar_expr, "1.61.0", Some(83527)),
/// Provides a way to concatenate identifiers using metavariable expressions.
(unstable, macro_metavar_expr_concat, "1.81.0", Some(124225)),
/// Allows `#[marker]` on certain traits allowing overlapping implementations.
(unstable, marker_trait_attr, "1.30.0", Some(29864)),
/// A minimal, sound subset of specialization intended to be used by the
/// standard library until the soundness issues with specialization
/// are fixed.
(unstable, min_specialization, "1.7.0", Some(31844)),
/// Allows qualified paths in struct expressions, struct patterns and tuple struct patterns.
(unstable, more_qualified_paths, "1.54.0", Some(86935)),
/// Allows the `#[must_not_suspend]` attribute.
(unstable, must_not_suspend, "1.57.0", Some(83310)),
/// Allows `mut ref` and `mut ref mut` identifier patterns.
(incomplete, mut_ref, "1.79.0", Some(123076)),
/// Allows using `#[naked]` on functions.
(unstable, naked_functions, "1.9.0", Some(90957)),
/// Allows specifying the as-needed link modifier
(unstable, native_link_modifiers_as_needed, "1.53.0", Some(81490)),
/// Allow negative trait implementations.
(unstable, negative_impls, "1.44.0", Some(68318)),
/// Allows the `!` pattern.
(incomplete, never_patterns, "1.76.0", Some(118155)),
/// Allows the `!` type. Does not imply 'exhaustive_patterns' (below) any more.
(unstable, never_type, "1.13.0", Some(35121)),
/// Allows diverging expressions to fall back to `!` rather than `()`.
(unstable, never_type_fallback, "1.41.0", Some(65992)),
/// Allows `#![no_core]`.
(unstable, no_core, "1.3.0", Some(29639)),
/// Allows the use of `no_sanitize` attribute.
(unstable, no_sanitize, "1.42.0", Some(39699)),
/// Allows using the `non_exhaustive_omitted_patterns` lint.
(unstable, non_exhaustive_omitted_patterns_lint, "1.57.0", Some(89554)),
/// Allows `for<T>` binders in where-clauses
(incomplete, non_lifetime_binders, "1.69.0", Some(108185)),
/// Allows using enums in offset_of!
(unstable, offset_of_enum, "1.75.0", Some(120141)),
/// Allows using fields with slice type in offset_of!
(unstable, offset_of_slice, "1.81.0", Some(126151)),
/// Allows using `#[optimize(X)]`.
(unstable, optimize_attribute, "1.34.0", Some(54882)),
/// Allows specifying nop padding on functions for dynamic patching.
(unstable, patchable_function_entry, "1.81.0", Some(123115)),
/// Experimental features that make `Pin` more ergonomic.
(incomplete, pin_ergonomics, "1.83.0", Some(130494)),
/// Allows postfix match `expr.match { ... }`
(unstable, postfix_match, "1.79.0", Some(121618)),
/// Allows `use<..>` precise capturign on impl Trait in traits.
(unstable, precise_capturing_in_traits, "1.83.0", Some(130044)),
/// Allows macro attributes on expressions, statements and non-inline modules.
(unstable, proc_macro_hygiene, "1.30.0", Some(54727)),
/// Makes `&` and `&mut` patterns eat only one layer of references in Rust 2024.
(incomplete, ref_pat_eat_one_layer_2024, "1.79.0", Some(123076)),
/// Makes `&` and `&mut` patterns eat only one layer of references in Rust 2024—structural variant
(incomplete, ref_pat_eat_one_layer_2024_structural, "1.81.0", Some(123076)),
/// Allows using the `#[register_tool]` attribute.
(unstable, register_tool, "1.41.0", Some(66079)),
/// Allows the `#[repr(i128)]` attribute for enums.
(incomplete, repr128, "1.16.0", Some(56071)),
/// Allows `repr(simd)` and importing the various simd intrinsics.
(unstable, repr_simd, "1.4.0", Some(27731)),
/// Allows bounding the return type of AFIT/RPITIT.
(unstable, return_type_notation, "1.70.0", Some(109417)),
/// Allows `extern "rust-cold"`.
(unstable, rust_cold_cc, "1.63.0", Some(97544)),
/// Allows use of x86 SHA512, SM3 and SM4 target-features and intrinsics
(unstable, sha512_sm_x86, "1.82.0", Some(126624)),
/// Allows the use of SIMD types in functions declared in `extern` blocks.
(unstable, simd_ffi, "1.0.0", Some(27731)),
/// Allows specialization of implementations (RFC 1210).
(incomplete, specialization, "1.7.0", Some(31844)),
/// Allows attributes on expressions and non-item statements.
(unstable, stmt_expr_attributes, "1.6.0", Some(15701)),
/// Allows lints part of the strict provenance effort.
(unstable, strict_provenance_lints, "1.61.0", Some(130351)),
/// Allows string patterns to dereference values to match them.
(unstable, string_deref_patterns, "1.67.0", Some(87121)),
/// Allows the use of `#[target_feature]` on safe functions.
(unstable, target_feature_11, "1.45.0", Some(69098)),
/// Allows using `#[thread_local]` on `static` items.
(unstable, thread_local, "1.0.0", Some(29594)),
/// Allows defining `trait X = A + B;` alias items.
(unstable, trait_alias, "1.24.0", Some(41517)),
/// Allows dyn upcasting trait objects via supertraits.
/// Dyn upcasting is casting, e.g., `dyn Foo -> dyn Bar` where `Foo: Bar`.
(unstable, trait_upcasting, "1.56.0", Some(65991)),
/// Allows for transmuting between arrays with sizes that contain generic consts.
(unstable, transmute_generic_consts, "1.70.0", Some(109929)),
/// Allows #[repr(transparent)] on unions (RFC 2645).
(unstable, transparent_unions, "1.37.0", Some(60405)),
/// Allows inconsistent bounds in where clauses.
(unstable, trivial_bounds, "1.28.0", Some(48214)),
/// Allows using `try {...}` expressions.
(unstable, try_blocks, "1.29.0", Some(31436)),
/// Allows `impl Trait` to be used inside type aliases (RFC 2515).
(unstable, type_alias_impl_trait, "1.38.0", Some(63063)),
/// Allows creation of instances of a struct by moving fields that have
/// not changed from prior instances of the same struct (RFC #2528)
(unstable, type_changing_struct_update, "1.58.0", Some(86555)),
/// Allows const generic parameters to be defined with types that
/// are not `Sized`, e.g. `fn foo<const N: [u8]>() {`.
(incomplete, unsized_const_params, "1.82.0", Some(95174)),
/// Allows unsized fn parameters.
(internal, unsized_fn_params, "1.49.0", Some(48055)),
/// Allows unsized rvalues at arguments and parameters.
(incomplete, unsized_locals, "1.30.0", Some(48055)),
/// Allows unsized tuple coercion.
(unstable, unsized_tuple_coercion, "1.20.0", Some(42877)),
/// Allows using the `#[used(linker)]` (or `#[used(compiler)]`) attribute.
(unstable, used_with_arg, "1.60.0", Some(93798)),
/// Allows use of x86 `AMX` target-feature attributes and intrinsics
(unstable, x86_amx_intrinsics, "1.81.0", Some(126622)),
/// Allows use of the `xop` target-feature
(unstable, xop_target_feature, "1.81.0", Some(127208)),
/// Allows `do yeet` expressions
(unstable, yeet_expr, "1.62.0", Some(96373)),
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// Features are listed in alphabetical order. Tidy will fail if you don't keep it this way.
// !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!! !!!!
// -------------------------------------------------------------------------
// feature-group-end: actual feature gates
// -------------------------------------------------------------------------
);
/// Some features are not allowed to be used together at the same time, if
/// the two are present, produce an error.
///
/// Currently empty, but we will probably need this again in the future,
/// so let's keep it in for now.
pub const INCOMPATIBLE_FEATURES: &[(Symbol, Symbol)] = &[];