compiler/rustc_feature/src/active.rs

   1 //! List of the active feature gates.
   2
   3 use super::{to_nonzero, Feature, State};
   4
   5 use rustc_span::edition::Edition;
   6 use rustc_span::symbol::{sym, Symbol};
   7 use rustc_span::Span;
   8
   9 macro_rules! set {
  10     ($field: ident) => {{
  11         fn f(features: &mut Features, _: Span) {
  12             features.$field = true;
  13         }
  14         f as fn(&mut Features, Span)
  15     }};
  16 }
  17
  18 macro_rules! declare_features {
  19     ($(
  20         $(#[doc = $doc:tt])* (active, $feature:ident, $ver:expr, $issue:expr, $edition:expr),
  21     )+) => {
  22         /// Represents active features that are currently being implemented or
  23         /// currently being considered for addition/removal.
  24         pub const ACTIVE_FEATURES:
  25             &[Feature] =
  26             &[$(
  27                 // (sym::$feature, $ver, $issue, $edition, set!($feature))
  28                 Feature {
  29                     state: State::Active { set: set!($feature) },
  30                     name: sym::$feature,
  31                     since: $ver,
  32                     issue: to_nonzero($issue),
  33                     edition: $edition,
  34                     description: concat!($($doc,)*),
  35                 }
  36             ),+];
  37
  38         /// A set of features to be used by later passes.
  39         #[derive(Clone, Default)]
  40         pub struct Features {
  41             /// `#![feature]` attrs for language features, for error reporting.
  42             pub declared_lang_features: Vec<(Symbol, Span, Option<Symbol>)>,
  43             /// `#![feature]` attrs for non-language (library) features.
  44             pub declared_lib_features: Vec<(Symbol, Span)>,
  45             $(
  46                 $(#[doc = $doc])*
  47                 pub $feature: bool
  48             ),+
  49         }
  50
  51         impl Features {
  52             pub fn walk_feature_fields(&self, mut f: impl FnMut(&str, bool)) {
  53                 $(f(stringify!($feature), self.$feature);)+
  54             }
  55
  56             /// Is the given feature enabled?
  57             ///
  58             /// Panics if the symbol doesn't correspond to a declared feature.
  59             pub fn enabled(&self, feature: Symbol) -> bool {
  60                 match feature {
  61                     $( sym::$feature => self.$feature, )*
  62
  63                     _ => panic!("`{}` was not listed in `declare_features`", feature),
  64                 }
  65             }
  66         }
  67     };
  68 }
  69
  70 impl Feature {
  71     /// Sets this feature in `Features`. Panics if called on a non-active feature.
  72     pub fn set(&self, features: &mut Features, span: Span) {
  73         match self.state {
  74             State::Active { set } => set(features, span),
  75             _ => panic!("called `set` on feature `{}` which is not `active`", self.name),
  76         }
  77     }
  78 }
  79
  80 // If you change this, please modify `src/doc/unstable-book` as well.
  81 //
  82 // Don't ever remove anything from this list; move them to `removed.rs`.
  83 //
  84 // The version numbers here correspond to the version in which the current status
  85 // was set. This is most important for knowing when a particular feature became
  86 // stable (active).
  87 //
  88 // Note that the features are grouped into internal/user-facing and then
  89 // sorted by version inside those groups. This is enforced with tidy.
  90 //
  91 // N.B., `tools/tidy/src/features.rs` parses this information directly out of the
  92 // source, so take care when modifying it.
  93
  94 #[rustfmt::skip]
  95 declare_features! (
  96     // -------------------------------------------------------------------------
  97     // feature-group-start: internal feature gates
  98     // -------------------------------------------------------------------------
  99
 100     // no-tracking-issue-start
 101
 102     /// Allows using `rustc_*` attributes (RFC 572).
 103     (active, rustc_attrs, "1.0.0", None, None),
 104
 105     /// Allows using compiler's own crates.
 106     (active, rustc_private, "1.0.0", Some(27812), None),
 107
 108     /// Allows using the `rust-intrinsic`'s "ABI".
 109     (active, intrinsics, "1.0.0", None, None),
 110
 111     /// Allows using `#[lang = ".."]` attribute for linking items to special compiler logic.
 112     (active, lang_items, "1.0.0", None, None),
 113
 114     /// Allows using the `#[stable]` and `#[unstable]` attributes.
 115     (active, staged_api, "1.0.0", None, None),
 116
 117     /// Allows using `#[allow_internal_unstable]`. This is an
 118     /// attribute on `macro_rules!` and can't use the attribute handling
 119     /// below (it has to be checked before expansion possibly makes
 120     /// macros disappear).
 121     (active, allow_internal_unstable, "1.0.0", None, None),
 122
 123     /// Allows using `#[allow_internal_unsafe]`. This is an
 124     /// attribute on `macro_rules!` and can't use the attribute handling
 125     /// below (it has to be checked before expansion possibly makes
 126     /// macros disappear).
 127     (active, allow_internal_unsafe, "1.0.0", None, None),
 128
 129     /// no-tracking-issue-end
 130
 131     /// Allows using `#[link_name="llvm.*"]`.
 132     (active, link_llvm_intrinsics, "1.0.0", Some(29602), None),
 133
 134     /// Allows using the `box $expr` syntax.
 135     (active, box_syntax, "1.0.0", Some(49733), None),
 136
 137     /// Allows using `#[main]` to replace the entrypoint `#[lang = "start"]` calls.
 138     (active, main, "1.0.0", Some(29634), None),
 139
 140     /// Allows using `#[start]` on a function indicating that it is the program entrypoint.
 141     (active, start, "1.0.0", Some(29633), None),
 142
 143     /// Allows using the `#[fundamental]` attribute.
 144     (active, fundamental, "1.0.0", Some(29635), None),
 145
 146     /// Allows using the `rust-call` ABI.
 147     (active, unboxed_closures, "1.0.0", Some(29625), None),
 148
 149     /// Allows using the `#[linkage = ".."]` attribute.
 150     (active, linkage, "1.0.0", Some(29603), None),
 151
 152     /// Allows features specific to OIBIT (auto traits).
 153     (active, optin_builtin_traits, "1.0.0", Some(13231), None),
 154
 155     /// Allows using `box` in patterns (RFC 469).
 156     (active, box_patterns, "1.0.0", Some(29641), None),
 157
 158     // no-tracking-issue-start
 159
 160     /// Allows using `#[prelude_import]` on glob `use` items.
 161     (active, prelude_import, "1.2.0", None, None),
 162
 163     // no-tracking-issue-end
 164
 165     // no-tracking-issue-start
 166
 167     /// Allows using `#[omit_gdb_pretty_printer_section]`.
 168     (active, omit_gdb_pretty_printer_section, "1.5.0", None, None),
 169
 170     /// Allows using the `vectorcall` ABI.
 171     (active, abi_vectorcall, "1.7.0", None, None),
 172
 173     // no-tracking-issue-end
 174
 175     /// Allows using `#[structural_match]` which indicates that a type is structurally matchable.
 176     /// FIXME: Subsumed by trait `StructuralPartialEq`, cannot move to removed until a library
 177     /// feature with the same name exists.
 178     (active, structural_match, "1.8.0", Some(31434), None),
 179
 180     /// Allows using the `may_dangle` attribute (RFC 1327).
 181     (active, dropck_eyepatch, "1.10.0", Some(34761), None),
 182
 183     /// Allows using the `#![panic_runtime]` attribute.
 184     (active, panic_runtime, "1.10.0", Some(32837), None),
 185
 186     /// Allows declaring with `#![needs_panic_runtime]` that a panic runtime is needed.
 187     (active, needs_panic_runtime, "1.10.0", Some(32837), None),
 188
 189     // no-tracking-issue-start
 190
 191     /// Allows identifying the `compiler_builtins` crate.
 192     (active, compiler_builtins, "1.13.0", None, None),
 193
 194     /// Allows using the `unadjusted` ABI; perma-unstable.
 195     (active, abi_unadjusted, "1.16.0", None, None),
 196
 197     /// Used to identify crates that contain the profiler runtime.
 198     (active, profiler_runtime, "1.18.0", None, None),
 199
 200     /// Allows using the `thiscall` ABI.
 201     (active, abi_thiscall, "1.19.0", None, None),
 202
 203     /// Allows using `#![needs_allocator]`, an implementation detail of `#[global_allocator]`.
 204     (active, allocator_internals, "1.20.0", None, None),
 205
 206     /// Added for testing E0705; perma-unstable.
 207     (active, test_2018_feature, "1.31.0", None, Some(Edition::Edition2018)),
 208
 209     /// Allows `#[repr(no_niche)]` (an implementation detail of `rustc`,
 210     /// it is not on path for eventual stabilization).
 211     (active, no_niche, "1.42.0", None, None),
 212
 213     /// Allows using `#[rustc_allow_const_fn_unstable]`.
 214     /// This is an attribute on `const fn` for the same
 215     /// purpose as `#[allow_internal_unstable]`.
 216     (active, rustc_allow_const_fn_unstable, "1.49.0", Some(69399), None),
 217
 218     // no-tracking-issue-end
 219
 220     // -------------------------------------------------------------------------
 221     // feature-group-end: internal feature gates
 222     // -------------------------------------------------------------------------
 223
 224     // -------------------------------------------------------------------------
 225     // feature-group-start: actual feature gates (target features)
 226     // -------------------------------------------------------------------------
 227
 228     // FIXME: Document these and merge with the list below.
 229
 230     // Unstable `#[target_feature]` directives.
 231     (active, arm_target_feature, "1.27.0", Some(44839), None),
 232     (active, aarch64_target_feature, "1.27.0", Some(44839), None),
 233     (active, hexagon_target_feature, "1.27.0", Some(44839), None),
 234     (active, powerpc_target_feature, "1.27.0", Some(44839), None),
 235     (active, mips_target_feature, "1.27.0", Some(44839), None),
 236     (active, avx512_target_feature, "1.27.0", Some(44839), None),
 237     (active, sse4a_target_feature, "1.27.0", Some(44839), None),
 238     (active, tbm_target_feature, "1.27.0", Some(44839), None),
 239     (active, wasm_target_feature, "1.30.0", Some(44839), None),
 240     (active, adx_target_feature, "1.32.0", Some(44839), None),
 241     (active, cmpxchg16b_target_feature, "1.32.0", Some(44839), None),
 242     (active, movbe_target_feature, "1.34.0", Some(44839), None),
 243     (active, rtm_target_feature, "1.35.0", Some(44839), None),
 244     (active, f16c_target_feature, "1.36.0", Some(44839), None),
 245     (active, riscv_target_feature, "1.45.0", Some(44839), None),
 246     (active, ermsb_target_feature, "1.49.0", Some(44839), None),
 247
 248     // -------------------------------------------------------------------------
 249     // feature-group-end: actual feature gates (target features)
 250     // -------------------------------------------------------------------------
 251
 252     // -------------------------------------------------------------------------
 253     // feature-group-start: actual feature gates
 254     // -------------------------------------------------------------------------
 255
 256     /// Allows using the `#[link_args]` attribute.
 257     (active, link_args, "1.0.0", Some(29596), None),
 258
 259     /// Allows defining identifiers beyond ASCII.
 260     (active, non_ascii_idents, "1.0.0", Some(55467), None),
 261
 262     /// Allows using `#[plugin_registrar]` on functions.
 263     (active, plugin_registrar, "1.0.0", Some(29597), None),
 264
 265     /// Allows using `#![plugin(myplugin)]`.
 266     (active, plugin, "1.0.0", Some(29597), None),
 267
 268     /// Allows using `#[thread_local]` on `static` items.
 269     (active, thread_local, "1.0.0", Some(29594), None),
 270
 271     /// Allows the use of SIMD types in functions declared in `extern` blocks.
 272     (active, simd_ffi, "1.0.0", Some(27731), None),
 273
 274     /// Allows using non lexical lifetimes (RFC 2094).
 275     (active, nll, "1.0.0", Some(43234), None),
 276
 277     /// Allows the definition of `const` functions with some advanced features.
 278     (active, const_fn, "1.2.0", Some(57563), None),
 279
 280     /// Allows associated type defaults.
 281     (active, associated_type_defaults, "1.2.0", Some(29661), None),
 282
 283     /// Allows `#![no_core]`.
 284     (active, no_core, "1.3.0", Some(29639), None),
 285
 286     /// Allows default type parameters to influence type inference.
 287     (active, default_type_parameter_fallback, "1.3.0", Some(27336), None),
 288
 289     /// Allows `repr(simd)` and importing the various simd intrinsics.
 290     (active, repr_simd, "1.4.0", Some(27731), None),
 291
 292     /// Allows `extern "platform-intrinsic" { ... }`.
 293     (active, platform_intrinsics, "1.4.0", Some(27731), None),
 294
 295     /// Allows `#[unwind(..)]`.
 296     ///
 297     /// Permits specifying whether a function should permit unwinding or abort on unwind.
 298     (active, unwind_attributes, "1.4.0", Some(58760), None),
 299
 300     /// Allows attributes on expressions and non-item statements.
 301     (active, stmt_expr_attributes, "1.6.0", Some(15701), None),
 302
 303     /// Allows the use of type ascription in expressions.
 304     (active, type_ascription, "1.6.0", Some(23416), None),
 305
 306     /// Allows `cfg(target_thread_local)`.
 307     (active, cfg_target_thread_local, "1.7.0", Some(29594), None),
 308
 309     /// Allows specialization of implementations (RFC 1210).
 310     (active, specialization, "1.7.0", Some(31844), None),
 311
 312     /// A minimal, sound subset of specialization intended to be used by the
 313     /// standard library until the soundness issues with specialization
 314     /// are fixed.
 315     (active, min_specialization, "1.7.0", Some(31844), None),
 316
 317     /// Allows using `#[naked]` on functions.
 318     (active, naked_functions, "1.9.0", Some(32408), None),
 319
 320     /// Allows `cfg(target_has_atomic = "...")`.
 321     (active, cfg_target_has_atomic, "1.9.0", Some(32976), None),
 322
 323     /// Allows `X..Y` patterns.
 324     (active, exclusive_range_pattern, "1.11.0", Some(37854), None),
 325
 326     /// Allows the `!` type. Does not imply 'exhaustive_patterns' (below) any more.
 327     (active, never_type, "1.13.0", Some(35121), None),
 328
 329     /// Allows exhaustive pattern matching on types that contain uninhabited types.
 330     (active, exhaustive_patterns, "1.13.0", Some(51085), None),
 331
 332     /// Allows `union`s to implement `Drop`. Moreover, `union`s may now include fields
 333     /// that don't implement `Copy` as long as they don't have any drop glue.
 334     /// This is checked recursively. On encountering type variable where no progress can be made,
 335     /// `T: Copy` is used as a substitute for "no drop glue".
 336     ///
 337     /// NOTE: A limited form of `union U { ... }` was accepted in 1.19.0.
 338     (active, untagged_unions, "1.13.0", Some(55149), None),
 339
 340     /// Allows `#[link(..., cfg(..))]`.
 341     (active, link_cfg, "1.14.0", Some(37406), None),
 342
 343     /// Allows `extern "ptx-*" fn()`.
 344     (active, abi_ptx, "1.15.0", Some(38788), None),
 345
 346     /// Allows the `#[repr(i128)]` attribute for enums.
 347     (active, repr128, "1.16.0", Some(56071), None),
 348
 349     /// Allows `#[link(kind="static-nobundle"...)]`.
 350     (active, static_nobundle, "1.16.0", Some(37403), None),
 351
 352     /// Allows `extern "msp430-interrupt" fn()`.
 353     (active, abi_msp430_interrupt, "1.16.0", Some(38487), None),
 354
 355     /// Allows declarative macros 2.0 (`macro`).
 356     (active, decl_macro, "1.17.0", Some(39412), None),
 357
 358     /// Allows `extern "x86-interrupt" fn()`.
 359     (active, abi_x86_interrupt, "1.17.0", Some(40180), None),
 360
 361     /// Allows a test to fail without failing the whole suite.
 362     (active, allow_fail, "1.19.0", Some(46488), None),
 363
 364     /// Allows unsized tuple coercion.
 365     (active, unsized_tuple_coercion, "1.20.0", Some(42877), None),
 366
 367     /// Allows defining generators.
 368     (active, generators, "1.21.0", Some(43122), None),
 369
 370     /// Allows `#[doc(cfg(...))]`.
 371     (active, doc_cfg, "1.21.0", Some(43781), None),
 372
 373     /// Allows `#[doc(masked)]`.
 374     (active, doc_masked, "1.21.0", Some(44027), None),
 375
 376     /// Allows `#[doc(spotlight)]`.
 377     (active, doc_spotlight, "1.22.0", Some(45040), None),
 378
 379     /// Allows `#[doc(include = "some-file")]`.
 380     (active, external_doc, "1.22.0", Some(44732), None),
 381
 382     /// Allows using `crate` as visibility modifier, synonymous with `pub(crate)`.
 383     (active, crate_visibility_modifier, "1.23.0", Some(53120), None),
 384
 385     /// Allows defining `extern type`s.
 386     (active, extern_types, "1.23.0", Some(43467), None),
 387
 388     /// Allows trait methods with arbitrary self types.
 389     (active, arbitrary_self_types, "1.23.0", Some(44874), None),
 390
 391     /// Allows in-band quantification of lifetime bindings (e.g., `fn foo(x: &'a u8) -> &'a u8`).
 392     (active, in_band_lifetimes, "1.23.0", Some(44524), None),
 393
 394     /// Allows associated types to be generic, e.g., `type Foo<T>;` (RFC 1598).
 395     (active, generic_associated_types, "1.23.0", Some(44265), None),
 396
 397     /// Allows defining `trait X = A + B;` alias items.
 398     (active, trait_alias, "1.24.0", Some(41517), None),
 399
 400     /// Allows inferring `'static` outlives requirements (RFC 2093).
 401     (active, infer_static_outlives_requirements, "1.26.0", Some(54185), None),
 402
 403     /// Allows accessing fields of unions inside `const` functions.
 404     (active, const_fn_union, "1.27.0", Some(51909), None),
 405
 406     /// Allows casting raw pointers to `usize` during const eval.
 407     (active, const_raw_ptr_to_usize_cast, "1.27.0", Some(51910), None),
 408
 409     /// Allows dereferencing raw pointers during const eval.
 410     (active, const_raw_ptr_deref, "1.27.0", Some(51911), None),
 411
 412     /// Allows inconsistent bounds in where clauses.
 413     (active, trivial_bounds, "1.28.0", Some(48214), None),
 414
 415     /// Allows `'a: { break 'a; }`.
 416     (active, label_break_value, "1.28.0", Some(48594), None),
 417
 418     /// Allows using `#[doc(keyword = "...")]`.
 419     (active, doc_keyword, "1.28.0", Some(51315), None),
 420
 421     /// Allows using `try {...}` expressions.
 422     (active, try_blocks, "1.29.0", Some(31436), None),
 423
 424     /// Allows defining an `#[alloc_error_handler]`.
 425     (active, alloc_error_handler, "1.29.0", Some(51540), None),
 426
 427     /// Allows using the `amdgpu-kernel` ABI.
 428     (active, abi_amdgpu_kernel, "1.29.0", Some(51575), None),
 429
 430     /// Allows panicking during const eval (producing compile-time errors).
 431     (active, const_panic, "1.30.0", Some(51999), None),
 432
 433     /// Allows `#[marker]` on certain traits allowing overlapping implementations.
 434     (active, marker_trait_attr, "1.30.0", Some(29864), None),
 435
 436     /// Allows macro attributes on expressions, statements and non-inline modules.
 437     (active, proc_macro_hygiene, "1.30.0", Some(54727), None),
 438
 439     /// Allows unsized rvalues at arguments and parameters.
 440     (active, unsized_locals, "1.30.0", Some(48055), None),
 441
 442     /// Allows custom test frameworks with `#![test_runner]` and `#[test_case]`.
 443     (active, custom_test_frameworks, "1.30.0", Some(50297), None),
 444
 445     /// Allows non-builtin attributes in inner attribute position.
 446     (active, custom_inner_attributes, "1.30.0", Some(54726), None),
 447
 448     /// Allows `impl Trait` in bindings (`let`, `const`, `static`).
 449     (active, impl_trait_in_bindings, "1.30.0", Some(63065), None),
 450
 451     /// Allows using `reason` in lint attributes and the `#[expect(lint)]` lint check.
 452     (active, lint_reasons, "1.31.0", Some(54503), None),
 453
 454     /// Allows exhaustive integer pattern matching on `usize` and `isize`.
 455     (active, precise_pointer_size_matching, "1.32.0", Some(56354), None),
 456
 457     /// Allows using `#[ffi_returns_twice]` on foreign functions.
 458     (active, ffi_returns_twice, "1.34.0", Some(58314), None),
 459
 460     /// Allows const generic types (e.g. `struct Foo<const N: usize>(...);`).
 461     (active, const_generics, "1.34.0", Some(44580), None),
 462
 463     /// Allows using `#[optimize(X)]`.
 464     (active, optimize_attribute, "1.34.0", Some(54882), None),
 465
 466     /// Allows using C-variadics.
 467     (active, c_variadic, "1.34.0", Some(44930), None),
 468
 469     /// Allows the user of associated type bounds.
 470     (active, associated_type_bounds, "1.34.0", Some(52662), None),
 471
 472     /// Allows `if/while p && let q = r && ...` chains.
 473     (active, let_chains, "1.37.0", Some(53667), None),
 474
 475     /// Allows #[repr(transparent)] on unions (RFC 2645).
 476     (active, transparent_unions, "1.37.0", Some(60405), None),
 477
 478     /// Allows explicit discriminants on non-unit enum variants.
 479     (active, arbitrary_enum_discriminant, "1.37.0", Some(60553), None),
 480
 481     /// Allows `impl Trait` with multiple unrelated lifetimes.
 482     (active, member_constraints, "1.37.0", Some(61997), None),
 483
 484     /// Allows `async || body` closures.
 485     (active, async_closure, "1.37.0", Some(62290), None),
 486
 487     /// Allows `[x; N]` where `x` is a constant (RFC 2203).
 488     (active, const_in_array_repeat_expressions, "1.37.0", Some(49147), None),
 489
 490     /// Allows `impl Trait` to be used inside type aliases (RFC 2515).
 491     (active, type_alias_impl_trait, "1.38.0", Some(63063), None),
 492
 493     /// Allows the use of or-patterns (e.g., `0 | 1`).
 494     (active, or_patterns, "1.38.0", Some(54883), None),
 495
 496     /// Allows the definition of `const extern fn` and `const unsafe extern fn`.
 497     (active, const_extern_fn, "1.40.0", Some(64926), None),
 498
 499     /// Allows the use of raw-dylibs (RFC 2627).
 500     (active, raw_dylib, "1.40.0", Some(58713), None),
 501
 502     /// Allows making `dyn Trait` well-formed even if `Trait` is not object safe.
 503     /// In that case, `dyn Trait: Trait` does not hold. Moreover, coercions and
 504     /// casts in safe Rust to `dyn Trait` for such a `Trait` is also forbidden.
 505     (active, object_safe_for_dispatch, "1.40.0", Some(43561), None),
 506
 507     /// Allows using the `efiapi` ABI.
 508     (active, abi_efiapi, "1.40.0", Some(65815), None),
 509
 510     /// Allows `&raw const $place_expr` and `&raw mut $place_expr` expressions.
 511     (active, raw_ref_op, "1.41.0", Some(64490), None),
 512
 513     /// Allows diverging expressions to fall back to `!` rather than `()`.
 514     (active, never_type_fallback, "1.41.0", Some(65992), None),
 515
 516     /// Allows using the `#[register_attr]` attribute.
 517     (active, register_attr, "1.41.0", Some(66080), None),
 518
 519     /// Allows using the `#[register_tool]` attribute.
 520     (active, register_tool, "1.41.0", Some(66079), None),
 521
 522     /// Allows the use of `#[cfg(sanitize = "option")]`; set when -Zsanitizer is used.
 523     (active, cfg_sanitize, "1.41.0", Some(39699), None),
 524
 525     /// Allows using `..X`, `..=X`, `...X`, and `X..` as a pattern.
 526     (active, half_open_range_patterns, "1.41.0", Some(67264), None),
 527
 528     /// Allows using `&mut` in constant functions.
 529     (active, const_mut_refs, "1.41.0", Some(57349), None),
 530
 531     /// Allows bindings in the subpattern of a binding pattern.
 532     /// For example, you can write `x @ Some(y)`.
 533     (active, bindings_after_at, "1.41.0", Some(65490), None),
 534
 535     /// Allows `impl const Trait for T` syntax.
 536     (active, const_trait_impl, "1.42.0", Some(67792), None),
 537
 538     /// Allows `T: ?const Trait` syntax in bounds.
 539     (active, const_trait_bound_opt_out, "1.42.0", Some(67794), None),
 540
 541     /// Allows the use of `no_sanitize` attribute.
 542     (active, no_sanitize, "1.42.0", Some(39699), None),
 543
 544     // Allows limiting the evaluation steps of const expressions
 545     (active, const_eval_limit, "1.43.0", Some(67217), None),
 546
 547     /// Allow negative trait implementations.
 548     (active, negative_impls, "1.44.0", Some(68318), None),
 549
 550     /// Allows the use of `#[target_feature]` on safe functions.
 551     (active, target_feature_11, "1.45.0", Some(69098), None),
 552
 553     /// Allow conditional compilation depending on rust version
 554     (active, cfg_version, "1.45.0", Some(64796), None),
 555
 556     /// Allows the use of `#[ffi_pure]` on foreign functions.
 557     (active, ffi_pure, "1.45.0", Some(58329), None),
 558
 559     /// Allows the use of `#[ffi_const]` on foreign functions.
 560     (active, ffi_const, "1.45.0", Some(58328), None),
 561
 562     /// No longer treat an unsafe function as an unsafe block.
 563     (active, unsafe_block_in_unsafe_fn, "1.45.0", Some(71668), None),
 564
 565     /// Allows `extern "avr-interrupt" fn()` and `extern "avr-non-blocking-interrupt" fn()`.
 566     (active, abi_avr_interrupt, "1.45.0", Some(69664), None),
 567
 568     /// Be more precise when looking for live drops in a const context.
 569     (active, const_precise_live_drops, "1.46.0", Some(73255), None),
 570
 571     /// Allows capturing variables in scope using format_args!
 572     (active, format_args_capture, "1.46.0", Some(67984), None),
 573
 574     /// Lazily evaluate constants. This allows constants to depend on type parameters.
 575     (active, lazy_normalization_consts, "1.46.0", Some(72219), None),
 576
 577     /// Allows calling `transmute` in const fn
 578     (active, const_fn_transmute, "1.46.0", Some(53605), None),
 579
 580     /// The smallest useful subset of `const_generics`.
 581     (active, min_const_generics, "1.47.0", Some(74878), None),
 582
 583     /// Allows `if let` guard in match arms.
 584     (active, if_let_guard, "1.47.0", Some(51114), None),
 585
 586     /// Allows non-trivial generic constants which have to be manually propageted upwards.
 587     (active, const_evaluatable_checked, "1.48.0", Some(76560), None),
 588
 589     /// Allows basic arithmetic on floating point types in a `const fn`.
 590     (active, const_fn_floating_point_arithmetic, "1.48.0", Some(57241), None),
 591
 592     /// Allows using and casting function pointers in a `const fn`.
 593     (active, const_fn_fn_ptr_basics, "1.48.0", Some(57563), None),
 594
 595     /// Allows to use the `#[cmse_nonsecure_entry]` attribute.
 596     (active, cmse_nonsecure_entry, "1.48.0", Some(75835), None),
 597
 598     /// Allows rustc to inject a default alloc_error_handler
 599     (active, default_alloc_error_handler, "1.48.0", Some(66741), None),
 600
 601     /// Allows argument and return position `impl Trait` in a `const fn`.
 602     (active, const_impl_trait, "1.48.0", Some(77463), None),
 603
 604     /// Allows `#[instruction_set(_)]` attribute
 605     (active, isa_attribute, "1.48.0", Some(74727), None),
 606
 607     /// Allow anonymous constants from an inline `const` block
 608     (active, inline_const, "1.49.0", Some(76001), None),
 609
 610     /// Allows unsized fn parameters.
 611     (active, unsized_fn_params, "1.49.0", Some(48055), None),
 612
 613     /// Allows the use of destructuring assignments.
 614     (active, destructuring_assignment, "1.49.0", Some(71126), None),
 615
 616     /// Enables `#[cfg(panic = "...")]` config key.
 617     (active, cfg_panic, "1.49.0", Some(77443), None),
 618
 619     // -------------------------------------------------------------------------
 620     // feature-group-end: actual feature gates
 621     // -------------------------------------------------------------------------
 622 );
 623
 624 /// Some features are known to be incomplete and using them is likely to have
 625 /// unanticipated results, such as compiler crashes. We warn the user about these
 626 /// to alert them.
 627 pub const INCOMPLETE_FEATURES: &[Symbol] = &[
 628     sym::if_let_guard,
 629     sym::impl_trait_in_bindings,
 630     sym::generic_associated_types,
 631     sym::const_generics,
 632     sym::let_chains,
 633     sym::raw_dylib,
 634     sym::const_evaluatable_checked,
 635     sym::const_trait_impl,
 636     sym::const_trait_bound_opt_out,
 637     sym::lazy_normalization_consts,
 638     sym::specialization,
 639     sym::inline_const,
 640     sym::repr128,
 641     sym::unsized_locals,
 642 ];
 643
 644 /// Some features are not allowed to be used together at the same time, if
 645 /// the two are present, produce an error.
 646 pub const INCOMPATIBLE_FEATURES: &[(Symbol, Symbol)] =
 647     &[(sym::const_generics, sym::min_const_generics)];