Up to date list of available nightly features?
The Unstable Book has a list of features, but some features are not documented there.
A complete list of features is contained in the source code (or the current master branch). To date, active features are:
declare_features! (
// -------------------------------------------------------------------------
// feature-group-start: internal feature gates
// -------------------------------------------------------------------------
// no-tracking-issue-start
/// Allows using compiler's own crates.
(active, rustc_private, "1.0.0", Some(27812), None),
/// Allows using the `rust-intrinsic`'s "ABI".
(active, intrinsics, "1.0.0", None, None),
/// Allows using `#[lang = ".."]` attribute for linking items to special compiler logic.
(active, lang_items, "1.0.0", None, None),
/// Allows using the `#[stable]` and `#[unstable]` attributes.
(active, staged_api, "1.0.0", None, 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).
(active, allow_internal_unstable, "1.0.0", None, 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).
(active, allow_internal_unsafe, "1.0.0", None, None),
/// no-tracking-issue-end
/// Allows using `#[link_name="llvm.*"]`.
(active, link_llvm_intrinsics, "1.0.0", Some(29602), None),
/// Allows using `rustc_*` attributes (RFC 572).
(active, rustc_attrs, "1.0.0", Some(29642), None),
/// Allows using the `box $expr` syntax.
(active, box_syntax, "1.0.0", Some(49733), None),
/// Allows using `#[main]` to replace the entrypoint `#[lang = "start"]` calls.
(active, main, "1.0.0", Some(29634), None),
/// Allows using `#[start]` on a function indicating that it is the program entrypoint.
(active, start, "1.0.0", Some(29633), None),
/// Allows using the `#[fundamental]` attribute.
(active, fundamental, "1.0.0", Some(29635), None),
/// Allows using the `rust-call` ABI.
(active, unboxed_closures, "1.0.0", Some(29625), None),
/// Allows using the `#[linkage = ".."]` attribute.
(active, linkage, "1.0.0", Some(29603), None),
/// Allows features specific to OIBIT (auto traits).
(active, optin_builtin_traits, "1.0.0", Some(13231), None),
/// Allows using `box` in patterns (RFC 469).
(active, box_patterns, "1.0.0", Some(29641), None),
// no-tracking-issue-start
/// Allows using `#[prelude_import]` on glob `use` items.
(active, prelude_import, "1.2.0", None, None),
// no-tracking-issue-end
// no-tracking-issue-start
/// Allows using `#[omit_gdb_pretty_printer_section]`.
(active, omit_gdb_pretty_printer_section, "1.5.0", None, None),
/// Allows using the `vectorcall` ABI.
(active, abi_vectorcall, "1.7.0", None, None),
// no-tracking-issue-end
/// Allows using `#[structural_match]` which indicates that a type is structurally matchable.
(active, structural_match, "1.8.0", Some(31434), None),
/// Allows using the `may_dangle` attribute (RFC 1327).
(active, dropck_eyepatch, "1.10.0", Some(34761), None),
/// Allows using the `#![panic_runtime]` attribute.
(active, panic_runtime, "1.10.0", Some(32837), None),
/// Allows declaring with `#![needs_panic_runtime]` that a panic runtime is needed.
(active, needs_panic_runtime, "1.10.0", Some(32837), None),
// no-tracking-issue-start
/// Allows identifying the `compiler_builtins` crate.
(active, compiler_builtins, "1.13.0", None, None),
/// Allows using the `unadjusted` ABI; perma-unstable.
(active, abi_unadjusted, "1.16.0", None, None),
/// Allows identifying crates that contain sanitizer runtimes.
(active, sanitizer_runtime, "1.17.0", None, None),
/// Used to identify crates that contain the profiler runtime.
(active, profiler_runtime, "1.18.0", None, None),
/// Allows using the `thiscall` ABI.
(active, abi_thiscall, "1.19.0", None, None),
/// Allows using `#![needs_allocator]`, an implementation detail of `#[global_allocator]`.
(active, allocator_internals, "1.20.0", None, None),
/// Added for testing E0705; perma-unstable.
(active, test_2018_feature, "1.31.0", None, Some(Edition::Edition2018)),
// no-tracking-issue-end
// -------------------------------------------------------------------------
// 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.
(active, arm_target_feature, "1.27.0", Some(44839), None),
(active, aarch64_target_feature, "1.27.0", Some(44839), None),
(active, hexagon_target_feature, "1.27.0", Some(44839), None),
(active, powerpc_target_feature, "1.27.0", Some(44839), None),
(active, mips_target_feature, "1.27.0", Some(44839), None),
(active, avx512_target_feature, "1.27.0", Some(44839), None),
(active, mmx_target_feature, "1.27.0", Some(44839), None),
(active, sse4a_target_feature, "1.27.0", Some(44839), None),
(active, tbm_target_feature, "1.27.0", Some(44839), None),
(active, wasm_target_feature, "1.30.0", Some(44839), None),
(active, adx_target_feature, "1.32.0", Some(44839), None),
(active, cmpxchg16b_target_feature, "1.32.0", Some(44839), None),
(active, movbe_target_feature, "1.34.0", Some(44839), None),
(active, rtm_target_feature, "1.35.0", Some(44839), None),
(active, f16c_target_feature, "1.36.0", Some(44839), None),
// -------------------------------------------------------------------------
// feature-group-end: actual feature gates (target features)
// -------------------------------------------------------------------------
// -------------------------------------------------------------------------
// feature-group-start: actual feature gates
// -------------------------------------------------------------------------
/// Allows using the `#[link_args]` attribute.
(active, link_args, "1.0.0", Some(29596), None),
/// Allows defining identifiers beyond ASCII.
(active, non_ascii_idents, "1.0.0", Some(55467), None),
/// Allows using `#[plugin_registrar]` on functions.
(active, plugin_registrar, "1.0.0", Some(29597), None),
/// Allows using `#![plugin(myplugin)]`.
(active, plugin, "1.0.0", Some(29597), None),
/// Allows using `#[thread_local]` on `static` items.
(active, thread_local, "1.0.0", Some(29594), None),
/// Allows the use of SIMD types in functions declared in `extern` blocks.
(active, simd_ffi, "1.0.0", Some(27731), None),
/// Allows using non lexical lifetimes (RFC 2094).
(active, nll, "1.0.0", Some(43234), None),
/// Allows using slice patterns.
(active, slice_patterns, "1.0.0", Some(62254), None),
/// Allows the definition of `const` functions with some advanced features.
(active, const_fn, "1.2.0", Some(57563), None),
/// Allows associated type defaults.
(active, associated_type_defaults, "1.2.0", Some(29661), None),
/// Allows `#![no_core]`.
(active, no_core, "1.3.0", Some(29639), None),
/// Allows default type parameters to influence type inference.
(active, default_type_parameter_fallback, "1.3.0", Some(27336), None),
/// Allows `repr(simd)` and importing the various simd intrinsics.
(active, repr_simd, "1.4.0", Some(27731), None),
/// Allows `extern "platform-intrinsic" { ... }`.
(active, platform_intrinsics, "1.4.0", Some(27731), None),
/// Allows `#[unwind(..)]`.
///
/// Permits specifying whether a function should permit unwinding or abort on unwind.
(active, unwind_attributes, "1.4.0", Some(58760), None),
/// Allows `#[no_debug]`.
(active, no_debug, "1.5.0", Some(29721), None),
/// Allows attributes on expressions and non-item statements.
(active, stmt_expr_attributes, "1.6.0", Some(15701), None),
/// Allows the use of type ascription in expressions.
(active, type_ascription, "1.6.0", Some(23416), None),
/// Allows `cfg(target_thread_local)`.
(active, cfg_target_thread_local, "1.7.0", Some(29594), None),
/// Allows specialization of implementations (RFC 1210).
(active, specialization, "1.7.0", Some(31844), None),
/// Allows using `#[naked]` on functions.
(active, naked_functions, "1.9.0", Some(32408), None),
/// Allows `cfg(target_has_atomic = "...")`.
(active, cfg_target_has_atomic, "1.9.0", Some(32976), None),
/// Allows `X..Y` patterns.
(active, exclusive_range_pattern, "1.11.0", Some(37854), None),
/// Allows the `!` type. Does not imply 'exhaustive_patterns' (below) any more.
(active, never_type, "1.13.0", Some(35121), None),
/// Allows exhaustive pattern matching on types that contain uninhabited types.
(active, exhaustive_patterns, "1.13.0", Some(51085), None),
/// Allows `union`s to implement `Drop`. Moreover, `union`s may now include fields
/// that don't implement `Copy` as long as they don't have any drop glue.
/// This is checked recursively. On encountering type variable where no progress can be made,
/// `T: Copy` is used as a substitute for "no drop glue".
///
/// NOTE: A limited form of `union U { ... }` was accepted in 1.19.0.
(active, untagged_unions, "1.13.0", Some(55149), None),
/// Allows `#[link(..., cfg(..))]`.
(active, link_cfg, "1.14.0", Some(37406), None),
/// Allows `extern "ptx-*" fn()`.
(active, abi_ptx, "1.15.0", Some(38788), None),
/// Allows the `#[repr(i128)]` attribute for enums.
(active, repr128, "1.16.0", Some(35118), None),
/// Allows `#[link(kind="static-nobundle"...)]`.
(active, static_nobundle, "1.16.0", Some(37403), None),
/// Allows `extern "msp430-interrupt" fn()`.
(active, abi_msp430_interrupt, "1.16.0", Some(38487), None),
/// Allows declarative macros 2.0 (`macro`).
(active, decl_macro, "1.17.0", Some(39412), None),
/// Allows `extern "x86-interrupt" fn()`.
(active, abi_x86_interrupt, "1.17.0", Some(40180), None),
/// Allows overlapping impls of marker traits.
(active, overlapping_marker_traits, "1.18.0", Some(29864), None),
/// Allows a test to fail without failing the whole suite.
(active, allow_fail, "1.19.0", Some(46488), None),
/// Allows unsized tuple coercion.
(active, unsized_tuple_coercion, "1.20.0", Some(42877), None),
/// Allows defining generators.
(active, generators, "1.21.0", Some(43122), None),
/// Allows `#[doc(cfg(...))]`.
(active, doc_cfg, "1.21.0", Some(43781), None),
/// Allows `#[doc(masked)]`.
(active, doc_masked, "1.21.0", Some(44027), None),
/// Allows `#[doc(spotlight)]`.
(active, doc_spotlight, "1.22.0", Some(45040), None),
/// Allows `#[doc(include = "some-file")]`.
(active, external_doc, "1.22.0", Some(44732), None),
/// Allows using `crate` as visibility modifier, synonymous with `pub(crate)`.
(active, crate_visibility_modifier, "1.23.0", Some(53120), None),
/// Allows defining `extern type`s.
(active, extern_types, "1.23.0", Some(43467), None),
/// Allows trait methods with arbitrary self types.
(active, arbitrary_self_types, "1.23.0", Some(44874), None),
/// Allows in-band quantification of lifetime bindings (e.g., `fn foo(x: &'a u8) -> &'a u8`).
(active, in_band_lifetimes, "1.23.0", Some(44524), None),
/// Allows associated types to be generic, e.g., `type Foo<T>;` (RFC 1598).
(active, generic_associated_types, "1.23.0", Some(44265), None),
/// Allows defining `trait X = A + B;` alias items.
(active, trait_alias, "1.24.0", Some(41517), None),
/// Allows infering `'static` outlives requirements (RFC 2093).
(active, infer_static_outlives_requirements, "1.26.0", Some(54185), None),
/// Allows accessing fields of unions inside `const` functions.
(active, const_fn_union, "1.27.0", Some(51909), None),
/// Allows casting raw pointers to `usize` during const eval.
(active, const_raw_ptr_to_usize_cast, "1.27.0", Some(51910), None),
/// Allows dereferencing raw pointers during const eval.
(active, const_raw_ptr_deref, "1.27.0", Some(51911), None),
/// Allows comparing raw pointers during const eval.
(active, const_compare_raw_pointers, "1.27.0", Some(53020), None),
/// Allows `#[doc(alias = "...")]`.
(active, doc_alias, "1.27.0", Some(50146), None),
/// Allows inconsistent bounds in where clauses.
(active, trivial_bounds, "1.28.0", Some(48214), None),
/// Allows `'a: { break 'a; }`.
(active, label_break_value, "1.28.0", Some(48594), None),
/// Allows using `#[doc(keyword = "...")]`.
(active, doc_keyword, "1.28.0", Some(51315), None),
/// Allows using `try {...}` expressions.
(active, try_blocks, "1.29.0", Some(31436), None),
/// Allows defining an `#[alloc_error_handler]`.
(active, alloc_error_handler, "1.29.0", Some(51540), None),
/// Allows using the `amdgpu-kernel` ABI.
(active, abi_amdgpu_kernel, "1.29.0", Some(51575), None),
/// Allows panicking during const eval (producing compile-time errors).
(active, const_panic, "1.30.0", Some(51999), None),
/// Allows `#[marker]` on certain traits allowing overlapping implementations.
(active, marker_trait_attr, "1.30.0", Some(29864), None),
/// Allows macro invocations on modules expressions and statements and
/// procedural macros to expand to non-items.
(active, proc_macro_hygiene, "1.30.0", Some(54727), None),
/// Allows unsized rvalues at arguments and parameters.
(active, unsized_locals, "1.30.0", Some(48055), None),
/// Allows custom test frameworks with `#![test_runner]` and `#[test_case]`.
(active, custom_test_frameworks, "1.30.0", Some(50297), None),
/// Allows non-builtin attributes in inner attribute position.
(active, custom_inner_attributes, "1.30.0", Some(54726), None),
/// Allows `impl Trait` in bindings (`let`, `const`, `static`).
(active, impl_trait_in_bindings, "1.30.0", Some(63065), None),
/// Allows using `reason` in lint attributes and the `#[expect(lint)]` lint check.
(active, lint_reasons, "1.31.0", Some(54503), None),
/// Allows exhaustive integer pattern matching on `usize` and `isize`.
(active, precise_pointer_size_matching, "1.32.0", Some(56354), None),
/// Allows using `#[ffi_returns_twice]` on foreign functions.
(active, ffi_returns_twice, "1.34.0", Some(58314), None),
/// Allows const generic types (e.g. `struct Foo<const N: usize>(...);`).
(active, const_generics, "1.34.0", Some(44580), None),
/// Allows using `#[optimize(X)]`.
(active, optimize_attribute, "1.34.0", Some(54882), None),
/// Allows using C-variadics.
(active, c_variadic, "1.34.0", Some(44930), None),
/// Allows the user of associated type bounds.
(active, associated_type_bounds, "1.34.0", Some(52662), None),
/// Allows `if/while p && let q = r && ...` chains.
(active, let_chains, "1.37.0", Some(53667), None),
/// Allows #[repr(transparent)] on enums (RFC 2645).
(active, transparent_enums, "1.37.0", Some(60405), None),
/// Allows #[repr(transparent)] on unions (RFC 2645).
(active, transparent_unions, "1.37.0", Some(60405), None),
/// Allows explicit discriminants on non-unit enum variants.
(active, arbitrary_enum_discriminant, "1.37.0", Some(60553), None),
/// Allows `impl Trait` with multiple unrelated lifetimes.
(active, member_constraints, "1.37.0", Some(61977), None),
/// Allows `async || body` closures.
(active, async_closure, "1.37.0", Some(62290), None),
/// Allows `[x; N]` where `x` is a constant (RFC 2203).
(active, const_in_array_repeat_expressions, "1.37.0", Some(49147), None),
/// Allows `impl Trait` to be used inside type aliases (RFC 2515).
(active, type_alias_impl_trait, "1.38.0", Some(63063), None),
/// Allows the use of or-patterns (e.g., `0 | 1`).
(active, or_patterns, "1.38.0", Some(54883), None),
/// Allows the definition of `const extern fn` and `const unsafe extern fn`.
(active, const_extern_fn, "1.40.0", Some(64926), None),
/// Allows the use of raw-dylibs (RFC 2627).
(active, raw_dylib, "1.40.0", Some(58713), None),
/// Allows `#[track_caller]` to be used which provides
/// accurate caller location reporting during panic (RFC 2091).
(active, track_caller, "1.40.0", Some(47809), None),
/// Allows making `dyn Trait` well-formed even if `Trait` is not object safe.
/// 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.
(active, object_safe_for_dispatch, "1.40.0", Some(43561), None),
/// Allows using the `efiapi` ABI.
(active, abi_efiapi, "1.40.0", Some(65815), None),
/// Allows `&raw const $place_expr` and `&raw mut $place_expr` expressions.
(active, raw_ref_op, "1.41.0", Some(64490), None),
/// Allows diverging expressions to fall back to `!` rather than `()`.
(active, never_type_fallback, "1.41.0", Some(65992), None),
/// Allows using the `#[register_attr]` attribute.
(active, register_attr, "1.41.0", Some(66080), None),
/// Allows using the `#[register_tool]` attribute.
(active, register_tool, "1.41.0", Some(66079), None),
/// Allows the use of `if` and `match` in constants.
(active, const_if_match, "1.41.0", Some(49146), None),
/// Allows the use of `#[cfg(sanitize = "option")]`; set when -Zsanitizer is used.
(active, cfg_sanitize, "1.41.0", Some(39699), None),
/// Allows using `&mut` in constant functions.
(active, const_mut_refs, "1.41.0", Some(57349), None),
/// Allows the use of `loop` and `while` in constants.
(active, const_loop, "1.41.0", Some(52000), None),
// -------------------------------------------------------------------------
// feature-group-end: actual feature gates
// -------------------------------------------------------------------------
);
Note than some of them are internal to rustc and not meant to be used, and that this list changes constently.
The source also contains a list of all features that were removed or accepted.
The file src/libsyntax/feature_gate.rs and the reference only list compiler features, but not api features. For example, the feature rc_counts is not listed.
Using this command:
ack -h --output '$1' 'unstable\(feature = "(\w+)"' $(ls -d * | grep -v -x test) | sort | uniq
on the Rust src dir, I got the following list:
alloc
alloc_jemalloc
alloc_system
arc_counts
as_unsafe_cell
binary_heap_append
binary_heap_extras
borrow_state
box_heap
btree_append
btree_range
btree_split_off
cell_extras
cell_get_mut
coerce_unsized
collection_placement
collections
collections_bound
collections_range
core_char_ext
core_float
core_intrinsics
core_panic
core_private_bignum
core_private_diy_float
core_slice_ext
core_str_ext
c_void_variant
dec2flt
deque_extras
derive_clone_copy
enumset
error_type_id
exit_status_from
filling_drop
fixed_size_array
float_extras
flt2dec
fmt_flags_align
fmt_internals
fnbox
fn_traits
get_type_id
heap_api
inclusive_range
integer_atomics
int_error_internals
io
io_error_internals
ip
ipv6_to_octets
iter_arith
libstd_io_internals
libstd_sys_internals
libstd_thread_internals
linked_list_contains
linked_list_extras
lookup_host
mpsc_select
nonzero
once_poison
oom
panic_abort
panic_unwind
pattern
peekable_is_empty
placement_in
placement_new_protocol
print
process_exec
pthread_t
rand
range_contains
raw
rc_counts
rc_would_unwrap
reflect_marker
rt
rustc_private
rustdoc
set_stdio
shared
slice_concat_ext
static_condvar
static_mutex
static_rwlock
step_by
step_trait
str_char
str_escape
str_internals
test
thread_local_internals
thread_local_state
try_from
unicode
unique
unsize
vec_deque_contains
zero_one
Maybe "The Unstable Book"?
- I don't copy & paste the content here because it's constantly changing so very likely to be invalidated soon.