1 //! List of the active feature gates.
3 use super::{to_nonzero, Feature, State};
5 use rustc_span::edition::Edition;
6 use rustc_span::symbol::{sym, Symbol};
11 fn f(features: &mut Features, _: Span) {
12 features.$field = true;
14 f as fn(&mut Features, Span)
18 macro_rules! declare_features {
20 $(#[doc = $doc:tt])* (active, $feature:ident, $ver:expr, $issue:expr, $edition:expr),
22 /// Represents active features that are currently being implemented or
23 /// currently being considered for addition/removal.
24 pub const ACTIVE_FEATURES:
27 // (sym::$feature, $ver, $issue, $edition, set!($feature))
29 state: State::Active { set: set!($feature) },
32 issue: to_nonzero($issue),
34 description: concat!($($doc,)*),
38 /// A set of features to be used by later passes.
39 #[derive(Clone, Default, Debug)]
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)>,
52 pub fn walk_feature_fields(&self, mut f: impl FnMut(&str, bool)) {
53 $(f(stringify!($feature), self.$feature);)+
56 /// Is the given feature enabled?
58 /// Panics if the symbol doesn't correspond to a declared feature.
59 pub fn enabled(&self, feature: Symbol) -> bool {
61 $( sym::$feature => self.$feature, )*
63 _ => panic!("`{}` was not listed in `declare_features`", 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) {
74 State::Active { set } => set(features, span),
75 _ => panic!("called `set` on feature `{}` which is not `active`", self.name),
80 // If you change this, please modify `src/doc/unstable-book` as well.
82 // Don't ever remove anything from this list; move them to `removed.rs`.
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
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.
91 // N.B., `tools/tidy/src/features.rs` parses this information directly out of the
92 // source, so take care when modifying it.
96 // -------------------------------------------------------------------------
97 // feature-group-start: internal feature gates
98 // -------------------------------------------------------------------------
100 // no-tracking-issue-start
102 /// Allows using `rustc_*` attributes (RFC 572).
103 (active, rustc_attrs, "1.0.0", None, None),
105 /// Allows using compiler's own crates.
106 (active, rustc_private, "1.0.0", Some(27812), None),
108 /// Allows using the `rust-intrinsic`'s "ABI".
109 (active, intrinsics, "1.0.0", None, None),
111 /// Allows using `#[lang = ".."]` attribute for linking items to special compiler logic.
112 (active, lang_items, "1.0.0", None, None),
114 /// Allows using the `#[stable]` and `#[unstable]` attributes.
115 (active, staged_api, "1.0.0", None, None),
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),
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),
129 /// no-tracking-issue-end
131 /// Allows using `#[link_name="llvm.*"]`.
132 (active, link_llvm_intrinsics, "1.0.0", Some(29602), None),
134 /// Allows using the `box $expr` syntax.
135 (active, box_syntax, "1.0.0", Some(49733), None),
137 /// Allows using `#[main]` to replace the entrypoint `#[lang = "start"]` calls.
138 (active, main, "1.0.0", Some(29634), None),
140 /// Allows using `#[start]` on a function indicating that it is the program entrypoint.
141 (active, start, "1.0.0", Some(29633), None),
143 /// Allows using the `#[fundamental]` attribute.
144 (active, fundamental, "1.0.0", Some(29635), None),
146 /// Allows using the `rust-call` ABI.
147 (active, unboxed_closures, "1.0.0", Some(29625), None),
149 /// Allows using the `#[linkage = ".."]` attribute.
150 (active, linkage, "1.0.0", Some(29603), None),
152 /// Allows using `box` in patterns (RFC 469).
153 (active, box_patterns, "1.0.0", Some(29641), None),
155 // no-tracking-issue-start
157 /// Allows using `#[prelude_import]` on glob `use` items.
158 (active, prelude_import, "1.2.0", None, None),
160 // no-tracking-issue-end
162 // no-tracking-issue-start
164 /// Allows using `#[omit_gdb_pretty_printer_section]`.
165 (active, omit_gdb_pretty_printer_section, "1.5.0", None, None),
167 /// Allows using the `vectorcall` ABI.
168 (active, abi_vectorcall, "1.7.0", None, None),
170 // no-tracking-issue-end
172 /// Allows using `#[structural_match]` which indicates that a type is structurally matchable.
173 /// FIXME: Subsumed by trait `StructuralPartialEq`, cannot move to removed until a library
174 /// feature with the same name exists.
175 (active, structural_match, "1.8.0", Some(31434), None),
177 /// Allows using the `may_dangle` attribute (RFC 1327).
178 (active, dropck_eyepatch, "1.10.0", Some(34761), None),
180 /// Allows using the `#![panic_runtime]` attribute.
181 (active, panic_runtime, "1.10.0", Some(32837), None),
183 /// Allows declaring with `#![needs_panic_runtime]` that a panic runtime is needed.
184 (active, needs_panic_runtime, "1.10.0", Some(32837), None),
186 // no-tracking-issue-start
188 /// Allows identifying the `compiler_builtins` crate.
189 (active, compiler_builtins, "1.13.0", None, None),
191 /// Allows using the `unadjusted` ABI; perma-unstable.
192 (active, abi_unadjusted, "1.16.0", None, None),
194 /// Used to identify crates that contain the profiler runtime.
195 (active, profiler_runtime, "1.18.0", None, None),
197 /// Allows using the `thiscall` ABI.
198 (active, abi_thiscall, "1.19.0", None, None),
200 /// Allows using `#![needs_allocator]`, an implementation detail of `#[global_allocator]`.
201 (active, allocator_internals, "1.20.0", None, None),
203 /// Added for testing E0705; perma-unstable.
204 (active, test_2018_feature, "1.31.0", None, Some(Edition::Edition2018)),
206 /// Allows `#[repr(no_niche)]` (an implementation detail of `rustc`,
207 /// it is not on path for eventual stabilization).
208 (active, no_niche, "1.42.0", None, None),
210 /// Allows using `#[rustc_allow_const_fn_unstable]`.
211 /// This is an attribute on `const fn` for the same
212 /// purpose as `#[allow_internal_unstable]`.
213 (active, rustc_allow_const_fn_unstable, "1.49.0", Some(69399), None),
215 /// Allows features specific to auto traits.
216 /// Renamed from `optin_builtin_traits`.
217 (active, auto_traits, "1.50.0", Some(13231), None),
219 /// Allows `#[doc(notable_trait)]`.
220 /// Renamed from `doc_spotlight`.
221 (active, doc_notable_trait, "1.52.0", Some(45040), None),
223 // no-tracking-issue-end
225 // -------------------------------------------------------------------------
226 // feature-group-end: internal feature gates
227 // -------------------------------------------------------------------------
229 // -------------------------------------------------------------------------
230 // feature-group-start: actual feature gates (target features)
231 // -------------------------------------------------------------------------
233 // FIXME: Document these and merge with the list below.
235 // Unstable `#[target_feature]` directives.
236 (active, arm_target_feature, "1.27.0", Some(44839), None),
237 (active, aarch64_target_feature, "1.27.0", Some(44839), None),
238 (active, hexagon_target_feature, "1.27.0", Some(44839), None),
239 (active, powerpc_target_feature, "1.27.0", Some(44839), None),
240 (active, mips_target_feature, "1.27.0", Some(44839), None),
241 (active, avx512_target_feature, "1.27.0", Some(44839), None),
242 (active, sse4a_target_feature, "1.27.0", Some(44839), None),
243 (active, tbm_target_feature, "1.27.0", Some(44839), None),
244 (active, wasm_target_feature, "1.30.0", Some(44839), None),
245 (active, adx_target_feature, "1.32.0", Some(44839), None),
246 (active, cmpxchg16b_target_feature, "1.32.0", Some(44839), None),
247 (active, movbe_target_feature, "1.34.0", Some(44839), None),
248 (active, rtm_target_feature, "1.35.0", Some(44839), None),
249 (active, f16c_target_feature, "1.36.0", Some(44839), None),
250 (active, riscv_target_feature, "1.45.0", Some(44839), None),
251 (active, ermsb_target_feature, "1.49.0", Some(44839), None),
253 // -------------------------------------------------------------------------
254 // feature-group-end: actual feature gates (target features)
255 // -------------------------------------------------------------------------
257 // -------------------------------------------------------------------------
258 // feature-group-start: actual feature gates
259 // -------------------------------------------------------------------------
261 /// Allows defining identifiers beyond ASCII.
262 (active, non_ascii_idents, "1.0.0", Some(55467), None),
264 /// Allows using `#[plugin_registrar]` on functions.
265 (active, plugin_registrar, "1.0.0", Some(29597), None),
267 /// Allows using `#![plugin(myplugin)]`.
268 (active, plugin, "1.0.0", Some(29597), None),
270 /// Allows using `#[thread_local]` on `static` items.
271 (active, thread_local, "1.0.0", Some(29594), None),
273 /// Allows the use of SIMD types in functions declared in `extern` blocks.
274 (active, simd_ffi, "1.0.0", Some(27731), None),
276 /// Allows using non lexical lifetimes (RFC 2094).
277 (active, nll, "1.0.0", Some(43234), None),
279 /// Allows the definition of `const` functions with some advanced features.
280 (active, const_fn, "1.2.0", Some(57563), None),
282 /// Allows associated type defaults.
283 (active, associated_type_defaults, "1.2.0", Some(29661), None),
285 /// Allows `#![no_core]`.
286 (active, no_core, "1.3.0", Some(29639), None),
288 /// Allows default type parameters to influence type inference.
289 (active, default_type_parameter_fallback, "1.3.0", Some(27336), None),
291 /// Allows `repr(simd)` and importing the various simd intrinsics.
292 (active, repr_simd, "1.4.0", Some(27731), None),
294 /// Allows `extern "platform-intrinsic" { ... }`.
295 (active, platform_intrinsics, "1.4.0", Some(27731), None),
297 /// Allows `#[unwind(..)]`.
299 /// Permits specifying whether a function should permit unwinding or abort on unwind.
300 (active, unwind_attributes, "1.4.0", Some(58760), None),
302 /// Allows attributes on expressions and non-item statements.
303 (active, stmt_expr_attributes, "1.6.0", Some(15701), None),
305 /// Allows the use of type ascription in expressions.
306 (active, type_ascription, "1.6.0", Some(23416), None),
308 /// Allows `cfg(target_thread_local)`.
309 (active, cfg_target_thread_local, "1.7.0", Some(29594), None),
311 /// Allows specialization of implementations (RFC 1210).
312 (active, specialization, "1.7.0", Some(31844), None),
314 /// A minimal, sound subset of specialization intended to be used by the
315 /// standard library until the soundness issues with specialization
317 (active, min_specialization, "1.7.0", Some(31844), None),
319 /// Allows using `#[naked]` on functions.
320 (active, naked_functions, "1.9.0", Some(32408), None),
322 /// Allows `cfg(target_has_atomic = "...")`.
323 (active, cfg_target_has_atomic, "1.9.0", Some(32976), None),
325 /// Allows `X..Y` patterns.
326 (active, exclusive_range_pattern, "1.11.0", Some(37854), None),
328 /// Allows the `!` type. Does not imply 'exhaustive_patterns' (below) any more.
329 (active, never_type, "1.13.0", Some(35121), None),
331 /// Allows exhaustive pattern matching on types that contain uninhabited types.
332 (active, exhaustive_patterns, "1.13.0", Some(51085), None),
334 /// Allows `union`s to implement `Drop`. Moreover, `union`s may now include fields
335 /// that don't implement `Copy` as long as they don't have any drop glue.
336 /// This is checked recursively. On encountering type variable where no progress can be made,
337 /// `T: Copy` is used as a substitute for "no drop glue".
339 /// NOTE: A limited form of `union U { ... }` was accepted in 1.19.0.
340 (active, untagged_unions, "1.13.0", Some(55149), None),
342 /// Allows `#[link(..., cfg(..))]`.
343 (active, link_cfg, "1.14.0", Some(37406), None),
345 /// Allows `extern "ptx-*" fn()`.
346 (active, abi_ptx, "1.15.0", Some(38788), None),
348 /// Allows the `#[repr(i128)]` attribute for enums.
349 (active, repr128, "1.16.0", Some(56071), None),
351 /// Allows `#[link(kind="static-nobundle"...)]`.
352 (active, static_nobundle, "1.16.0", Some(37403), None),
354 /// Allows `extern "msp430-interrupt" fn()`.
355 (active, abi_msp430_interrupt, "1.16.0", Some(38487), None),
357 /// Allows declarative macros 2.0 (`macro`).
358 (active, decl_macro, "1.17.0", Some(39412), None),
360 /// Allows `extern "x86-interrupt" fn()`.
361 (active, abi_x86_interrupt, "1.17.0", Some(40180), None),
363 /// Allows a test to fail without failing the whole suite.
364 (active, allow_fail, "1.19.0", Some(46488), None),
366 /// Allows unsized tuple coercion.
367 (active, unsized_tuple_coercion, "1.20.0", Some(42877), None),
369 /// Allows defining generators.
370 (active, generators, "1.21.0", Some(43122), None),
372 /// Allows `#[doc(cfg(...))]`.
373 (active, doc_cfg, "1.21.0", Some(43781), None),
375 /// Allows `#[doc(masked)]`.
376 (active, doc_masked, "1.21.0", Some(44027), None),
378 /// Allows `#[doc(include = "some-file")]`.
379 (active, external_doc, "1.22.0", Some(44732), None),
381 /// Allows using `crate` as visibility modifier, synonymous with `pub(crate)`.
382 (active, crate_visibility_modifier, "1.23.0", Some(53120), None),
384 /// Allows defining `extern type`s.
385 (active, extern_types, "1.23.0", Some(43467), None),
387 /// Allows trait methods with arbitrary self types.
388 (active, arbitrary_self_types, "1.23.0", Some(44874), None),
390 /// Allows in-band quantification of lifetime bindings (e.g., `fn foo(x: &'a u8) -> &'a u8`).
391 (active, in_band_lifetimes, "1.23.0", Some(44524), None),
393 /// Allows associated types to be generic, e.g., `type Foo<T>;` (RFC 1598).
394 (active, generic_associated_types, "1.23.0", Some(44265), None),
396 /// Allows defining `trait X = A + B;` alias items.
397 (active, trait_alias, "1.24.0", Some(41517), None),
399 /// Allows inferring `'static` outlives requirements (RFC 2093).
400 (active, infer_static_outlives_requirements, "1.26.0", Some(54185), None),
402 /// Allows accessing fields of unions inside `const` functions.
403 (active, const_fn_union, "1.27.0", Some(51909), None),
405 /// Allows casting raw pointers to `usize` during const eval.
406 (active, const_raw_ptr_to_usize_cast, "1.27.0", Some(51910), None),
408 /// Allows dereferencing raw pointers during const eval.
409 (active, const_raw_ptr_deref, "1.27.0", Some(51911), None),
411 /// Allows inconsistent bounds in where clauses.
412 (active, trivial_bounds, "1.28.0", Some(48214), None),
414 /// Allows `'a: { break 'a; }`.
415 (active, label_break_value, "1.28.0", Some(48594), None),
417 /// Allows using `#[doc(keyword = "...")]`.
418 (active, doc_keyword, "1.28.0", Some(51315), None),
420 /// Allows using `try {...}` expressions.
421 (active, try_blocks, "1.29.0", Some(31436), None),
423 /// Allows defining an `#[alloc_error_handler]`.
424 (active, alloc_error_handler, "1.29.0", Some(51540), None),
426 /// Allows using the `amdgpu-kernel` ABI.
427 (active, abi_amdgpu_kernel, "1.29.0", Some(51575), None),
429 /// Allows panicking during const eval (producing compile-time errors).
430 (active, const_panic, "1.30.0", Some(51999), None),
432 /// Allows `#[marker]` on certain traits allowing overlapping implementations.
433 (active, marker_trait_attr, "1.30.0", Some(29864), None),
435 /// Allows macro attributes on expressions, statements and non-inline modules.
436 (active, proc_macro_hygiene, "1.30.0", Some(54727), None),
438 /// Allows unsized rvalues at arguments and parameters.
439 (active, unsized_locals, "1.30.0", Some(48055), None),
441 /// Allows custom test frameworks with `#![test_runner]` and `#[test_case]`.
442 (active, custom_test_frameworks, "1.30.0", Some(50297), None),
444 /// Allows non-builtin attributes in inner attribute position.
445 (active, custom_inner_attributes, "1.30.0", Some(54726), None),
447 /// Allows `impl Trait` in bindings (`let`, `const`, `static`).
448 (active, impl_trait_in_bindings, "1.30.0", Some(63065), None),
450 /// Allows using `reason` in lint attributes and the `#[expect(lint)]` lint check.
451 (active, lint_reasons, "1.31.0", Some(54503), None),
453 /// Allows exhaustive integer pattern matching on `usize` and `isize`.
454 (active, precise_pointer_size_matching, "1.32.0", Some(56354), None),
456 /// Allows using `#[ffi_returns_twice]` on foreign functions.
457 (active, ffi_returns_twice, "1.34.0", Some(58314), None),
459 /// Allows const generic types (e.g. `struct Foo<const N: usize>(...);`).
460 (active, const_generics, "1.34.0", Some(44580), None),
462 /// Allows using `#[optimize(X)]`.
463 (active, optimize_attribute, "1.34.0", Some(54882), None),
465 /// Allows using C-variadics.
466 (active, c_variadic, "1.34.0", Some(44930), None),
468 /// Allows the user of associated type bounds.
469 (active, associated_type_bounds, "1.34.0", Some(52662), None),
471 /// Allows `if/while p && let q = r && ...` chains.
472 (active, let_chains, "1.37.0", Some(53667), None),
474 /// Allows #[repr(transparent)] on unions (RFC 2645).
475 (active, transparent_unions, "1.37.0", Some(60405), None),
477 /// Allows explicit discriminants on non-unit enum variants.
478 (active, arbitrary_enum_discriminant, "1.37.0", Some(60553), None),
480 /// Allows `impl Trait` with multiple unrelated lifetimes.
481 (active, member_constraints, "1.37.0", Some(61997), None),
483 /// Allows `async || body` closures.
484 (active, async_closure, "1.37.0", Some(62290), None),
486 /// Allows `impl Trait` to be used inside type aliases (RFC 2515).
487 (active, type_alias_impl_trait, "1.38.0", Some(63063), None),
489 /// Allows the definition of `const extern fn` and `const unsafe extern fn`.
490 (active, const_extern_fn, "1.40.0", Some(64926), None),
492 /// Allows the use of raw-dylibs (RFC 2627).
493 (active, raw_dylib, "1.40.0", Some(58713), None),
495 /// Allows making `dyn Trait` well-formed even if `Trait` is not object safe.
496 /// In that case, `dyn Trait: Trait` does not hold. Moreover, coercions and
497 /// casts in safe Rust to `dyn Trait` for such a `Trait` is also forbidden.
498 (active, object_safe_for_dispatch, "1.40.0", Some(43561), None),
500 /// Allows using the `efiapi` ABI.
501 (active, abi_efiapi, "1.40.0", Some(65815), None),
503 /// Allows `&raw const $place_expr` and `&raw mut $place_expr` expressions.
504 (active, raw_ref_op, "1.41.0", Some(64490), None),
506 /// Allows diverging expressions to fall back to `!` rather than `()`.
507 (active, never_type_fallback, "1.41.0", Some(65992), None),
509 /// Allows using the `#[register_attr]` attribute.
510 (active, register_attr, "1.41.0", Some(66080), None),
512 /// Allows using the `#[register_tool]` attribute.
513 (active, register_tool, "1.41.0", Some(66079), None),
515 /// Allows the use of `#[cfg(sanitize = "option")]`; set when -Zsanitizer is used.
516 (active, cfg_sanitize, "1.41.0", Some(39699), None),
518 /// Allows using `..X`, `..=X`, `...X`, and `X..` as a pattern.
519 (active, half_open_range_patterns, "1.41.0", Some(67264), None),
521 /// Allows using `&mut` in constant functions.
522 (active, const_mut_refs, "1.41.0", Some(57349), None),
524 /// Allows bindings in the subpattern of a binding pattern.
525 /// For example, you can write `x @ Some(y)`.
526 (active, bindings_after_at, "1.41.0", Some(65490), None),
528 /// Allows `impl const Trait for T` syntax.
529 (active, const_trait_impl, "1.42.0", Some(67792), None),
531 /// Allows `T: ?const Trait` syntax in bounds.
532 (active, const_trait_bound_opt_out, "1.42.0", Some(67794), None),
534 /// Allows the use of `no_sanitize` attribute.
535 (active, no_sanitize, "1.42.0", Some(39699), None),
537 // Allows limiting the evaluation steps of const expressions
538 (active, const_eval_limit, "1.43.0", Some(67217), None),
540 /// Allow negative trait implementations.
541 (active, negative_impls, "1.44.0", Some(68318), None),
543 /// Allows the use of `#[target_feature]` on safe functions.
544 (active, target_feature_11, "1.45.0", Some(69098), None),
546 /// Allow conditional compilation depending on rust version
547 (active, cfg_version, "1.45.0", Some(64796), None),
549 /// Allows the use of `#[ffi_pure]` on foreign functions.
550 (active, ffi_pure, "1.45.0", Some(58329), None),
552 /// Allows the use of `#[ffi_const]` on foreign functions.
553 (active, ffi_const, "1.45.0", Some(58328), None),
555 /// Allows `extern "avr-interrupt" fn()` and `extern "avr-non-blocking-interrupt" fn()`.
556 (active, abi_avr_interrupt, "1.45.0", Some(69664), None),
558 /// Be more precise when looking for live drops in a const context.
559 (active, const_precise_live_drops, "1.46.0", Some(73255), None),
561 /// Allows capturing variables in scope using format_args!
562 (active, format_args_capture, "1.46.0", Some(67984), None),
564 /// Lazily evaluate constants. This allows constants to depend on type parameters.
565 (active, lazy_normalization_consts, "1.46.0", Some(72219), None),
567 /// Allows calling `transmute` in const fn
568 (active, const_fn_transmute, "1.46.0", Some(53605), None),
570 /// Allows `if let` guard in match arms.
571 (active, if_let_guard, "1.47.0", Some(51114), None),
573 /// Allows non-trivial generic constants which have to be manually propagated upwards.
574 (active, const_evaluatable_checked, "1.48.0", Some(76560), None),
576 /// Allows basic arithmetic on floating point types in a `const fn`.
577 (active, const_fn_floating_point_arithmetic, "1.48.0", Some(57241), None),
579 /// Allows using and casting function pointers in a `const fn`.
580 (active, const_fn_fn_ptr_basics, "1.48.0", Some(57563), None),
582 /// Allows to use the `#[cmse_nonsecure_entry]` attribute.
583 (active, cmse_nonsecure_entry, "1.48.0", Some(75835), None),
585 /// Allows rustc to inject a default alloc_error_handler
586 (active, default_alloc_error_handler, "1.48.0", Some(66741), None),
588 /// Allows argument and return position `impl Trait` in a `const fn`.
589 (active, const_impl_trait, "1.48.0", Some(77463), None),
591 /// Allows `#[instruction_set(_)]` attribute
592 (active, isa_attribute, "1.48.0", Some(74727), None),
594 /// Allow anonymous constants from an inline `const` block
595 (active, inline_const, "1.49.0", Some(76001), None),
597 /// Allows unsized fn parameters.
598 (active, unsized_fn_params, "1.49.0", Some(48055), None),
600 /// Allows the use of destructuring assignments.
601 (active, destructuring_assignment, "1.49.0", Some(71126), None),
603 /// Enables `#[cfg(panic = "...")]` config key.
604 (active, cfg_panic, "1.49.0", Some(77443), None),
606 /// Allows capturing disjoint fields in a closure/generator (RFC 2229).
607 (active, capture_disjoint_fields, "1.49.0", Some(53488), None),
609 /// Allows arbitrary expressions in key-value attributes at parse time.
610 (active, extended_key_value_attributes, "1.50.0", Some(78835), None),
612 /// `:pat2015` and `:pat2021` macro matchers.
613 (active, edition_macro_pats, "1.51.0", Some(54883), None),
615 /// Allows const generics to have default values (e.g. `struct Foo<const N: usize = 3>(...);`).
616 (active, const_generics_defaults, "1.51.0", Some(44580), None),
618 /// Allows references to types with interior mutability within constants
619 (active, const_refs_to_cell, "1.51.0", Some(80384), None),
621 /// Allows using `pointer` and `reference` in intra-doc links
622 (active, intra_doc_pointers, "1.51.0", Some(80896), None),
624 /// Allows `extern "C-cmse-nonsecure-call" fn()`.
625 (active, abi_c_cmse_nonsecure_call, "1.51.0", Some(81391), None),
627 /// Lessens the requirements for structs to implement `Unsize`.
628 (active, relaxed_struct_unsize, "1.51.0", Some(81793), None),
630 /// Allows macro attributes to observe output of `#[derive]`.
631 (active, macro_attributes_in_derive_output, "1.51.0", Some(81119), None),
633 /// Allows `pub` on `macro_rules` items.
634 (active, pub_macro_rules, "1.52.0", Some(78855), None),
636 /// Allows the use of type alias impl trait in function return positions
637 (active, min_type_alias_impl_trait, "1.52.0", Some(63063), None),
639 /// Allows associated types in inherent impls.
640 (active, inherent_associated_types, "1.52.0", Some(8995), None),
642 /// Allows `extern "C-unwind" fn` to enable unwinding across ABI boundaries.
643 (active, c_unwind, "1.52.0", Some(74990), None),
645 // -------------------------------------------------------------------------
646 // feature-group-end: actual feature gates
647 // -------------------------------------------------------------------------
650 /// Some features are known to be incomplete and using them is likely to have
651 /// unanticipated results, such as compiler crashes. We warn the user about these
653 pub const INCOMPLETE_FEATURES: &[Symbol] = &[
655 sym::impl_trait_in_bindings,
656 sym::generic_associated_types,
660 sym::const_evaluatable_checked,
661 sym::const_trait_impl,
662 sym::const_trait_bound_opt_out,
663 sym::lazy_normalization_consts,
668 sym::capture_disjoint_fields,
669 sym::const_generics_defaults,
670 sym::inherent_associated_types,
671 sym::type_alias_impl_trait,
674 /// Some features are not allowed to be used together at the same time, if
675 /// the two are present, produce an error.
677 /// Currently empty, but we will probably need this again in the future,
678 /// so let's keep it in for now.
679 pub const INCOMPATIBLE_FEATURES: &[(Symbol, Symbol)] = &[];