Struct rustc_feature::Features

pub struct Features {

    pub declared_lang_features: Vec<(Symbol, Span, Option<Symbol>)>,
    pub declared_lib_features: Vec<(Symbol, Span)>,
    pub rustc_attrs: bool,
    pub rustc_private: bool,
    pub intrinsics: bool,
    pub lang_items: bool,
    pub staged_api: bool,
    pub allow_internal_unstable: bool,
    pub allow_internal_unsafe: bool,
    pub link_llvm_intrinsics: bool,
    pub box_syntax: bool,
    pub start: bool,
    pub fundamental: bool,
    pub unboxed_closures: bool,
    pub linkage: bool,
    pub box_patterns: bool,
    pub prelude_import: bool,
    pub omit_gdb_pretty_printer_section: bool,
    pub abi_vectorcall: bool,
    pub structural_match: bool,
    pub dropck_eyepatch: bool,
    pub panic_runtime: bool,
    pub needs_panic_runtime: bool,
    pub compiler_builtins: bool,
    pub abi_unadjusted: bool,
    pub profiler_runtime: bool,
    pub abi_thiscall: bool,
    pub allocator_internals: bool,
    pub test_2018_feature: bool,
    pub no_niche: bool,
    pub rustc_allow_const_fn_unstable: bool,
    pub auto_traits: bool,
    pub doc_notable_trait: bool,
    pub arm_target_feature: bool,
    pub aarch64_target_feature: bool,
    pub hexagon_target_feature: bool,
    pub powerpc_target_feature: bool,
    pub mips_target_feature: bool,
    pub avx512_target_feature: bool,
    pub sse4a_target_feature: bool,
    pub tbm_target_feature: bool,
    pub wasm_target_feature: bool,
    pub adx_target_feature: bool,
    pub cmpxchg16b_target_feature: bool,
    pub movbe_target_feature: bool,
    pub rtm_target_feature: bool,
    pub f16c_target_feature: bool,
    pub riscv_target_feature: bool,
    pub ermsb_target_feature: bool,
    pub plugin_registrar: bool,
    pub plugin: bool,
    pub thread_local: bool,
    pub simd_ffi: bool,
    pub nll: bool,
    pub const_fn: bool,
    pub associated_type_defaults: bool,
    pub no_core: bool,
    pub default_type_parameter_fallback: bool,
    pub repr_simd: bool,
    pub platform_intrinsics: bool,
    pub unwind_attributes: bool,
    pub stmt_expr_attributes: bool,
    pub type_ascription: bool,
    pub cfg_target_thread_local: bool,
    pub specialization: bool,
    pub min_specialization: bool,
    pub naked_functions: bool,
    pub cfg_target_has_atomic: bool,
    pub exclusive_range_pattern: bool,
    pub never_type: bool,
    pub exhaustive_patterns: bool,
    pub untagged_unions: bool,
    pub link_cfg: bool,
    pub abi_ptx: bool,
    pub repr128: bool,
    pub static_nobundle: bool,
    pub abi_msp430_interrupt: bool,
    pub decl_macro: bool,
    pub abi_x86_interrupt: bool,
    pub allow_fail: bool,
    pub unsized_tuple_coercion: bool,
    pub generators: bool,
    pub doc_cfg: bool,
    pub doc_masked: bool,
    pub external_doc: bool,
    pub crate_visibility_modifier: bool,
    pub extern_types: bool,
    pub arbitrary_self_types: bool,
    pub in_band_lifetimes: bool,
    pub generic_associated_types: bool,
    pub trait_alias: bool,
    pub infer_static_outlives_requirements: bool,
    pub const_fn_union: bool,
    pub const_raw_ptr_to_usize_cast: bool,
    pub const_raw_ptr_deref: bool,
    pub trivial_bounds: bool,
    pub label_break_value: bool,
    pub doc_keyword: bool,
    pub try_blocks: bool,
    pub alloc_error_handler: bool,
    pub abi_amdgpu_kernel: bool,
    pub const_panic: bool,
    pub marker_trait_attr: bool,
    pub proc_macro_hygiene: bool,
    pub unsized_locals: bool,
    pub custom_test_frameworks: bool,
    pub custom_inner_attributes: bool,
    pub impl_trait_in_bindings: bool,
    pub lint_reasons: bool,
    pub precise_pointer_size_matching: bool,
    pub ffi_returns_twice: bool,
    pub const_generics: bool,
    pub optimize_attribute: bool,
    pub c_variadic: bool,
    pub associated_type_bounds: bool,
    pub let_chains: bool,
    pub transparent_unions: bool,
    pub arbitrary_enum_discriminant: bool,
    pub member_constraints: bool,
    pub async_closure: bool,
    pub type_alias_impl_trait: bool,
    pub const_extern_fn: bool,
    pub raw_dylib: bool,
    pub object_safe_for_dispatch: bool,
    pub abi_efiapi: bool,
    pub raw_ref_op: bool,
    pub never_type_fallback: bool,
    pub register_attr: bool,
    pub register_tool: bool,
    pub cfg_sanitize: bool,
    pub half_open_range_patterns: bool,
    pub const_mut_refs: bool,
    pub bindings_after_at: bool,
    pub const_trait_impl: bool,
    pub const_trait_bound_opt_out: bool,
    pub no_sanitize: bool,
    pub const_eval_limit: bool,
    pub negative_impls: bool,
    pub target_feature_11: bool,
    pub cfg_version: bool,
    pub ffi_pure: bool,
    pub ffi_const: bool,
    pub abi_avr_interrupt: bool,
    pub const_precise_live_drops: bool,
    pub format_args_capture: bool,
    pub lazy_normalization_consts: bool,
    pub const_fn_transmute: bool,
    pub if_let_guard: bool,
    pub const_evaluatable_checked: bool,
    pub const_fn_floating_point_arithmetic: bool,
    pub const_fn_fn_ptr_basics: bool,
    pub cmse_nonsecure_entry: bool,
    pub default_alloc_error_handler: bool,
    pub const_impl_trait: bool,
    pub isa_attribute: bool,
    pub inline_const: bool,
    pub unsized_fn_params: bool,
    pub destructuring_assignment: bool,
    pub cfg_panic: bool,
    pub capture_disjoint_fields: bool,
    pub extended_key_value_attributes: bool,
    pub const_generics_defaults: bool,
    pub const_refs_to_cell: bool,
    pub intra_doc_pointers: bool,
    pub abi_c_cmse_nonsecure_call: bool,
    pub relaxed_struct_unsize: bool,
    pub macro_attributes_in_derive_output: bool,
    pub min_type_alias_impl_trait: bool,
    pub inherent_associated_types: bool,
    pub large_assignments: bool,
    pub c_unwind: bool,
    pub fn_align: bool,
    pub wasm_abi: bool,
    pub no_coverage: bool,
    pub const_fn_trait_bound: bool,
    pub const_fn_unsize: bool,
    pub imported_main: bool,
    pub native_link_modifiers: bool,
    pub native_link_modifiers_bundle: bool,
    pub native_link_modifiers_verbatim: bool,
    pub native_link_modifiers_whole_archive: bool,
    pub native_link_modifiers_as_needed: bool,
}

A set of features to be used by later passes.

Fields

declared_lang_features: Vec<(Symbol, Span, Option<Symbol>)>

#![feature] attrs for language features, for error reporting.

declared_lib_features: Vec<(Symbol, Span)>

#![feature] attrs for non-language (library) features.

rustc_attrs: bool

Allows using rustc_* attributes (RFC 572).

rustc_private: bool

Allows using compiler’s own crates.

intrinsics: bool

Allows using the rust-intrinsic’s “ABI”.

lang_items: bool

Allows using #[lang = ".."] attribute for linking items to special compiler logic.

staged_api: bool

Allows using the #[stable] and #[unstable] attributes.

allow_internal_unstable: bool

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).

allow_internal_unsafe: bool

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).

link_llvm_intrinsics: bool

no-tracking-issue-end Allows using #[link_name="llvm.*"].

box_syntax: bool

Allows using the box $expr syntax.

start: bool

Allows using #[start] on a function indicating that it is the program entrypoint.

fundamental: bool

Allows using the #[fundamental] attribute.

unboxed_closures: bool

Allows using the rust-call ABI.

linkage: bool

Allows using the #[linkage = ".."] attribute.

box_patterns: bool

Allows using box in patterns (RFC 469).

prelude_import: bool

Allows using #[prelude_import] on glob use items.

omit_gdb_pretty_printer_section: bool

Allows using #[omit_gdb_pretty_printer_section].

abi_vectorcall: bool

Allows using the vectorcall ABI.

structural_match: bool

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.

dropck_eyepatch: bool

Allows using the may_dangle attribute (RFC 1327).

panic_runtime: bool

Allows using the #![panic_runtime] attribute.

needs_panic_runtime: bool

Allows declaring with #![needs_panic_runtime] that a panic runtime is needed.

compiler_builtins: bool

Allows identifying the compiler_builtins crate.

abi_unadjusted: bool

Allows using the unadjusted ABI; perma-unstable.

profiler_runtime: bool

Used to identify crates that contain the profiler runtime.

abi_thiscall: bool

Allows using the thiscall ABI.

allocator_internals: bool

Allows using #![needs_allocator], an implementation detail of #[global_allocator].

test_2018_feature: bool

Added for testing E0705; perma-unstable.

no_niche: bool

Allows #[repr(no_niche)] (an implementation detail of rustc, it is not on path for eventual stabilization).

rustc_allow_const_fn_unstable: bool

Allows using #[rustc_allow_const_fn_unstable]. This is an attribute on const fn for the same purpose as #[allow_internal_unstable].

auto_traits: bool

Allows features specific to auto traits. Renamed from optin_builtin_traits.

doc_notable_trait: bool

Allows #[doc(notable_trait)]. Renamed from doc_spotlight.

arm_target_feature: bool

aarch64_target_feature: bool

hexagon_target_feature: bool

powerpc_target_feature: bool

mips_target_feature: bool

avx512_target_feature: bool

sse4a_target_feature: bool

tbm_target_feature: bool

wasm_target_feature: bool

adx_target_feature: bool

cmpxchg16b_target_feature: bool

movbe_target_feature: bool

rtm_target_feature: bool

f16c_target_feature: bool

riscv_target_feature: bool

ermsb_target_feature: bool

plugin_registrar: bool

Allows using #[plugin_registrar] on functions.

plugin: bool

Allows using #![plugin(myplugin)].

thread_local: bool

Allows using #[thread_local] on static items.

simd_ffi: bool

Allows the use of SIMD types in functions declared in extern blocks.

nll: bool

Allows using non lexical lifetimes (RFC 2094).

const_fn: bool

Allows the definition of const functions with some advanced features.

associated_type_defaults: bool

Allows associated type defaults.

no_core: bool

Allows #![no_core].

default_type_parameter_fallback: bool

Allows default type parameters to influence type inference.

repr_simd: bool

Allows repr(simd) and importing the various simd intrinsics.

platform_intrinsics: bool

Allows extern "platform-intrinsic" { ... }.

unwind_attributes: bool

Allows #[unwind(..)].

Permits specifying whether a function should permit unwinding or abort on unwind.

stmt_expr_attributes: bool

Allows attributes on expressions and non-item statements.

type_ascription: bool

Allows the use of type ascription in expressions.

cfg_target_thread_local: bool

Allows cfg(target_thread_local).

specialization: bool

Allows specialization of implementations (RFC 1210).

min_specialization: bool

A minimal, sound subset of specialization intended to be used by the standard library until the soundness issues with specialization are fixed.

naked_functions: bool

Allows using #[naked] on functions.

cfg_target_has_atomic: bool

Allows cfg(target_has_atomic = "...").

exclusive_range_pattern: bool

Allows X..Y patterns.

never_type: bool

Allows the ! type. Does not imply ‘exhaustive_patterns’ (below) any more.

exhaustive_patterns: bool

Allows exhaustive pattern matching on types that contain uninhabited types.

untagged_unions: bool

Allows unions to implement Drop. Moreover, unions 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.

link_cfg: bool

Allows #[link(..., cfg(..))].

abi_ptx: bool

Allows extern "ptx-*" fn().

repr128: bool

Allows the #[repr(i128)] attribute for enums.

static_nobundle: bool

Allows #[link(kind="static-nobundle"...)].

abi_msp430_interrupt: bool

Allows extern "msp430-interrupt" fn().

decl_macro: bool

Allows declarative macros 2.0 (macro).

abi_x86_interrupt: bool

Allows extern "x86-interrupt" fn().

allow_fail: bool

Allows a test to fail without failing the whole suite.

unsized_tuple_coercion: bool

Allows unsized tuple coercion.

generators: bool

Allows defining generators.

doc_cfg: bool

Allows #[doc(cfg(...))].

doc_masked: bool

Allows #[doc(masked)].

external_doc: bool

Allows #[doc(include = "some-file")].

crate_visibility_modifier: bool

Allows using crate as visibility modifier, synonymous with pub(crate).

extern_types: bool

Allows defining extern types.

arbitrary_self_types: bool

Allows trait methods with arbitrary self types.

in_band_lifetimes: bool

Allows in-band quantification of lifetime bindings (e.g., fn foo(x: &'a u8) -> &'a u8).

generic_associated_types: bool

Allows associated types to be generic, e.g., type Foo<T>; (RFC 1598).

trait_alias: bool

Allows defining trait X = A + B; alias items.

infer_static_outlives_requirements: bool

Allows inferring 'static outlives requirements (RFC 2093).

const_fn_union: bool

Allows accessing fields of unions inside const functions.

const_raw_ptr_to_usize_cast: bool

Allows casting raw pointers to usize during const eval.

const_raw_ptr_deref: bool

Allows dereferencing raw pointers during const eval.

trivial_bounds: bool

Allows inconsistent bounds in where clauses.

label_break_value: bool

Allows 'a: { break 'a; }.

doc_keyword: bool

Allows using #[doc(keyword = "...")].

try_blocks: bool

Allows using try {...} expressions.

alloc_error_handler: bool

Allows defining an #[alloc_error_handler].

abi_amdgpu_kernel: bool

Allows using the amdgpu-kernel ABI.

const_panic: bool

Allows panicking during const eval (producing compile-time errors).

marker_trait_attr: bool

Allows #[marker] on certain traits allowing overlapping implementations.

proc_macro_hygiene: bool

Allows macro attributes on expressions, statements and non-inline modules.

unsized_locals: bool

Allows unsized rvalues at arguments and parameters.

custom_test_frameworks: bool

Allows custom test frameworks with #![test_runner] and #[test_case].

custom_inner_attributes: bool

Allows non-builtin attributes in inner attribute position.

impl_trait_in_bindings: bool

Allows impl Trait in bindings (let, const, static).

lint_reasons: bool

Allows using reason in lint attributes and the #[expect(lint)] lint check.

precise_pointer_size_matching: bool

Allows exhaustive integer pattern matching on usize and isize.

ffi_returns_twice: bool

Allows using #[ffi_returns_twice] on foreign functions.

const_generics: bool

Allows const generic types (e.g. struct Foo<const N: usize>(...);).

optimize_attribute: bool

Allows using #[optimize(X)].

c_variadic: bool

Allows using C-variadics.

associated_type_bounds: bool

Allows the user of associated type bounds.

let_chains: bool

Allows if/while p && let q = r && ... chains.

transparent_unions: bool

Allows #[repr(transparent)] on unions (RFC 2645).

arbitrary_enum_discriminant: bool

Allows explicit discriminants on non-unit enum variants.

member_constraints: bool

Allows impl Trait with multiple unrelated lifetimes.

async_closure: bool

Allows async || body closures.

type_alias_impl_trait: bool

Allows impl Trait to be used inside type aliases (RFC 2515).

const_extern_fn: bool

Allows the definition of const extern fn and const unsafe extern fn.

raw_dylib: bool

Allows the use of raw-dylibs (RFC 2627).

object_safe_for_dispatch: bool

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.

abi_efiapi: bool

Allows using the efiapi ABI.

raw_ref_op: bool

Allows &raw const $place_expr and &raw mut $place_expr expressions.

never_type_fallback: bool

Allows diverging expressions to fall back to ! rather than ().

register_attr: bool

Allows using the #[register_attr] attribute.

register_tool: bool

Allows using the #[register_tool] attribute.

cfg_sanitize: bool

Allows the use of #[cfg(sanitize = "option")]; set when -Zsanitizer is used.

half_open_range_patterns: bool

Allows using ..X, ..=X, ...X, and X.. as a pattern.

const_mut_refs: bool

Allows using &mut in constant functions.

bindings_after_at: bool

Allows bindings in the subpattern of a binding pattern. For example, you can write x @ Some(y).

const_trait_impl: bool

Allows impl const Trait for T syntax.

const_trait_bound_opt_out: bool

Allows T: ?const Trait syntax in bounds.

no_sanitize: bool

Allows the use of no_sanitize attribute.

const_eval_limit: bool

negative_impls: bool

Allow negative trait implementations.

target_feature_11: bool

Allows the use of #[target_feature] on safe functions.

cfg_version: bool

Allow conditional compilation depending on rust version

ffi_pure: bool

Allows the use of #[ffi_pure] on foreign functions.

ffi_const: bool

Allows the use of #[ffi_const] on foreign functions.

abi_avr_interrupt: bool

Allows extern "avr-interrupt" fn() and extern "avr-non-blocking-interrupt" fn().

const_precise_live_drops: bool

Be more precise when looking for live drops in a const context.

format_args_capture: bool

Allows capturing variables in scope using format_args!

lazy_normalization_consts: bool

Lazily evaluate constants. This allows constants to depend on type parameters.

const_fn_transmute: bool

Allows calling transmute in const fn

if_let_guard: bool

Allows if let guard in match arms.

const_evaluatable_checked: bool

Allows non-trivial generic constants which have to be manually propagated upwards.

const_fn_floating_point_arithmetic: bool

Allows basic arithmetic on floating point types in a const fn.

const_fn_fn_ptr_basics: bool

Allows using and casting function pointers in a const fn.

cmse_nonsecure_entry: bool

Allows to use the #[cmse_nonsecure_entry] attribute.

default_alloc_error_handler: bool

Allows rustc to inject a default alloc_error_handler

const_impl_trait: bool

Allows argument and return position impl Trait in a const fn.

isa_attribute: bool

Allows #[instruction_set(_)] attribute

inline_const: bool

Allow anonymous constants from an inline const block

unsized_fn_params: bool

Allows unsized fn parameters.

destructuring_assignment: bool

Allows the use of destructuring assignments.

cfg_panic: bool

Enables #[cfg(panic = "...")] config key.

capture_disjoint_fields: bool

Allows capturing disjoint fields in a closure/generator (RFC 2229).

extended_key_value_attributes: bool

Allows arbitrary expressions in key-value attributes at parse time.

const_generics_defaults: bool

Allows const generics to have default values (e.g. struct Foo<const N: usize = 3>(...);).

const_refs_to_cell: bool

Allows references to types with interior mutability within constants

intra_doc_pointers: bool

Allows using pointer and reference in intra-doc links

abi_c_cmse_nonsecure_call: bool

Allows extern "C-cmse-nonsecure-call" fn().

relaxed_struct_unsize: bool

Lessens the requirements for structs to implement Unsize.

macro_attributes_in_derive_output: bool

Allows macro attributes to observe output of #[derive].

min_type_alias_impl_trait: bool

Allows the use of type alias impl trait in function return positions

inherent_associated_types: bool

Allows associated types in inherent impls.

large_assignments: bool

c_unwind: bool

Allows extern "C-unwind" fn to enable unwinding across ABI boundaries.

fn_align: bool

Allows using #[repr(align(...))] on function items

wasm_abi: bool

Allows extern "wasm" fn

no_coverage: bool

Allows function attribute #[no_coverage], to bypass coverage instrumentation of that function.

const_fn_trait_bound: bool

Allows trait bounds in const fn.

const_fn_unsize: bool

Allows unsizing coercions in const fn.

imported_main: bool

Allows using imported main function

native_link_modifiers: bool

Allows specifying modifiers in the link attribute: #[link(modifiers = "...")]

native_link_modifiers_bundle: bool

Allows specifying the bundle link modifier

native_link_modifiers_verbatim: bool

Allows specifying the verbatim link modifier

native_link_modifiers_whole_archive: bool

Allows specifying the whole-archive link modifier

native_link_modifiers_as_needed: bool

Allows specifying the as-needed link modifier

Implementations

impl Features

pub fn walk_feature_fields(&self, f: impl FnMut(&str, bool))

pub fn enabled(&self, feature: Symbol) -> bool

Is the given feature enabled?

Panics if the symbol doesn’t correspond to a declared feature.

pub fn unordered_const_ty_params(&self) -> bool

Trait Implementations

impl Clone for Features

fn clone(&self) -> Features

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Features

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Features

fn default() -> Features

Returns the “default value” for a type.