1//! Defines lang items.2//!3//! Language items are items that represent concepts intrinsic to the language4//! itself. Examples are:5//!6//! * Traits that specify "kinds"; e.g., `Sync`, `Send`.7//! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`.8//! * Functions called by the compiler itself.910use rustc_data_structures::fx::FxIndexMap;11use rustc_data_structures::stable_hash::{StableHash, StableHashCtxt, StableHasher};12use rustc_macros::{BlobDecodable, Encodable, PrintAttribute, StableHash};13use rustc_span::def_id::DefId;14use rustc_span::{Symbol, kw, sym};1516use crate::PrintAttribute;17use crate::target::{AssocCtxt, MethodKind, Target};1819/// All of the lang items, defined or not.20/// Defined lang items can come from the current crate or its dependencies.21#[derive(StableHash, Debug)]22pub struct LanguageItems {23    /// Mappings from lang items to their possibly found [`DefId`]s.24    /// The index corresponds to the order in [`LangItem`].25    items: [Option<DefId>; std::mem::variant_count::<LangItem>()],26    reverse_items: FxIndexMap<DefId, LangItem>,27    /// Lang items that were not found during collection.28    pub missing: Vec<LangItem>,29}3031impl LanguageItems {32    /// Construct an empty collection of lang items and no missing ones.33    pub fn new() -> Self {34        Self {35            items: [None; std::mem::variant_count::<LangItem>()],36            reverse_items: FxIndexMap::default(),37            missing: Vec::new(),38        }39    }4041    pub fn get(&self, item: LangItem) -> Option<DefId> {42        self.items[item as usize]43    }4445    pub fn set(&mut self, item: LangItem, def_id: DefId) {46        self.items[item as usize] = Some(def_id);47        let preexisting = self.reverse_items.insert(def_id, item);4849        // This needs to be a bijection.50        if let Some(preexisting) = preexisting {51            panic!(52                "For the bijection of LangItem <=> DefId to work,\53                one item DefId may only be assigned one LangItem. \54                Separate the LangItem definitions for {item:?} and {preexisting:?}."55            );56        }57    }5859    pub fn from_def_id(&self, def_id: DefId) -> Option<LangItem> {60        self.reverse_items.get(&def_id).copied()61    }6263    pub fn iter(&self) -> impl Iterator<Item = (LangItem, DefId)> {64        self.items65            .iter()66            .enumerate()67            .filter_map(|(i, id)| id.map(|id| (LangItem::from_u32(i as u32).unwrap(), id)))68    }6970    /// Remove any missing items from the list that aren't actually missing71    pub fn trim_missing(&mut self) {72        self.missing.retain(|&item| self.items[item as usize].is_none());73    }74}7576// The actual lang items defined come at the end of this file in one handy table.77// So you probably just want to nip down to the end.78macro_rules! language_item_table {79    (80        $( $(#[$attr:meta])* $variant:ident, $module:ident :: $name:ident, $method:ident, $target:expr, $generics:expr; )*81    ) => {82        /// A representation of all the valid lang items in Rust.83        #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Encodable, BlobDecodable, PrintAttribute)]84        pub enum LangItem {85            $(86                #[doc = concat!("The `", stringify!($name), "` lang item.")]87                $(#[$attr])*88                $variant,89            )*90        }9192        impl LangItem {93            fn from_u32(u: u32) -> Option<LangItem> {94                // This implementation is clumsy, but makes no assumptions95                // about how discriminant tags are allocated within the96                // range `0 .. std::mem::variant_count::<LangItem>()`.97                $(if u == LangItem::$variant as u32 {98                    return Some(LangItem::$variant)99                })*100                None101            }102103            /// Returns the `name` symbol in `#[lang = "$name"]`.104            /// For example, [`LangItem::PartialEq`]`.name()`105            /// would result in [`sym::eq`] since it is `#[lang = "eq"]`.106            pub fn name(self) -> Symbol {107                match self {108                    $( LangItem::$variant => $module::$name, )*109                }110            }111112            /// Opposite of [`LangItem::name`]113            pub fn from_name(name: Symbol) -> Option<Self> {114                match name {115                    $( $module::$name => Some(LangItem::$variant), )*116                    _ => None,117                }118            }119120            /// Returns the name of the `LangItem` enum variant.121            // This method is used by Clippy for internal lints.122            pub fn variant_name(self) -> &'static str {123                match self {124                    $( LangItem::$variant => stringify!($variant), )*125                }126            }127128            pub fn target(self) -> Target {129                match self {130                    $( LangItem::$variant => $target, )*131                }132            }133134            pub fn required_generics(&self) -> GenericRequirement {135                match self {136                    $( LangItem::$variant => $generics, )*137                }138            }139        }140141        impl LanguageItems {142            $(143                #[doc = concat!("Returns the [`DefId`] of the `", stringify!($name), "` lang item if it is defined.")]144                pub fn $method(&self) -> Option<DefId> {145                    self.items[LangItem::$variant as usize]146                }147            )*148        }149    }150}151152impl StableHash for LangItem {153    fn stable_hash<Hcx: StableHashCtxt>(&self, _: &mut Hcx, hasher: &mut StableHasher) {154        ::std::hash::Hash::hash(self, hasher);155    }156}157158language_item_table! {159//  Variant name,            Name,                     Getter method name,         Target                  Generic requirements;160    Sized,                   sym::sized,               sized_trait,                Target::Trait,          GenericRequirement::Exact(0);161    MetaSized,               sym::meta_sized,          meta_sized_trait,           Target::Trait,          GenericRequirement::Exact(0);162    PointeeSized,            sym::pointee_sized,       pointee_sized_trait,        Target::Trait,          GenericRequirement::Exact(0);163    Unsize,                  sym::unsize,              unsize_trait,               Target::Trait,          GenericRequirement::Minimum(1);164    AlignOf,                 sym::mem_align_const,     align_const,                Target::AssocConst(AssocCtxt::Trait),     GenericRequirement::Exact(0);165    SizeOf,                  sym::mem_size_const,      size_const,                 Target::AssocConst(AssocCtxt::Trait),     GenericRequirement::Exact(0);166    OffsetOf,                sym::offset_of,           offset_of,                  Target::Fn,             GenericRequirement::Exact(1);167    /// Trait injected by `#[derive(PartialEq)]`, (i.e. "Partial EQ").168    StructuralPeq,           sym::structural_peq,      structural_peq_trait,       Target::Trait,          GenericRequirement::None;169    Copy,                    sym::copy,                copy_trait,                 Target::Trait,          GenericRequirement::Exact(0);170    Clone,                   sym::clone,               clone_trait,                Target::Trait,          GenericRequirement::None;171    CloneFn,                 sym::clone_fn,            clone_fn,                   Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;172    UseCloned,               sym::use_cloned,          use_cloned_trait,           Target::Trait,          GenericRequirement::None;173    TrivialClone,            sym::trivial_clone,       trivial_clone_trait,        Target::Trait,          GenericRequirement::None;174    Sync,                    sym::sync,                sync_trait,                 Target::Trait,          GenericRequirement::Exact(0);175    DiscriminantKind,        sym::discriminant_kind,   discriminant_kind_trait,    Target::Trait,          GenericRequirement::None;176    /// The associated item of the `DiscriminantKind` trait.177    Discriminant,            sym::discriminant_type,   discriminant_type,          Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::None;178179    PointeeTrait,            sym::pointee_trait,       pointee_trait,              Target::Trait,          GenericRequirement::None;180    Metadata,                sym::metadata_type,       metadata_type,              Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::None;181    DynMetadata,             sym::dyn_metadata,        dyn_metadata,               Target::Struct,         GenericRequirement::None;182183    NonNull,                 sym::non_null,            non_null_trait,             Target::Struct,         GenericRequirement::Exact(1);184185    Freeze,                  sym::freeze,              freeze_trait,               Target::Trait,          GenericRequirement::Exact(0);186    UnsafeUnpin,             sym::unsafe_unpin,        unsafe_unpin_trait,         Target::Trait,          GenericRequirement::Exact(0);187188    FnPtrTrait,              sym::fn_ptr_trait,        fn_ptr_trait,               Target::Trait,          GenericRequirement::Exact(0);189    FnPtrAsPtr,              sym::fn_ptr_as_ptr,       fn_ptr_as_ptr,              Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;190    FnPtrFromPtr,            sym::fn_ptr_from_ptr,     fn_ptr_from_ptr,            Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;191    Code,                    sym::code,                code,                       Target::ForeignTy,      GenericRequirement::None;192193    Drop,                    sym::drop,                drop_trait,                 Target::Trait,          GenericRequirement::None;194    Destruct,                sym::destruct,            destruct_trait,             Target::Trait,          GenericRequirement::None;195    AsyncDrop,               sym::async_drop,          async_drop_trait,           Target::Trait,          GenericRequirement::None;196    AsyncDropInPlace,        sym::async_drop_in_place, async_drop_in_place_fn,     Target::Fn,             GenericRequirement::Exact(1);197198    CoerceUnsized,           sym::coerce_unsized,      coerce_unsized_trait,       Target::Trait,          GenericRequirement::Minimum(1);199    DispatchFromDyn,         sym::dispatch_from_dyn,   dispatch_from_dyn_trait,    Target::Trait,          GenericRequirement::Minimum(1);200201    TryAsDyn,                sym::try_as_dyn,          try_as_dyn,                 Target::Trait,          GenericRequirement::Exact(1);202203    // lang items relating to transmutability204    TransmuteOpts,           sym::transmute_opts,      transmute_opts,             Target::Struct,         GenericRequirement::Exact(0);205    TransmuteTrait,          sym::transmute_trait,     transmute_trait,            Target::Trait,          GenericRequirement::Exact(2);206207    Add,                     sym::add,                 add_trait,                  Target::Trait,          GenericRequirement::Exact(1);208    Sub,                     sym::sub,                 sub_trait,                  Target::Trait,          GenericRequirement::Exact(1);209    Mul,                     sym::mul,                 mul_trait,                  Target::Trait,          GenericRequirement::Exact(1);210    Div,                     sym::div,                 div_trait,                  Target::Trait,          GenericRequirement::Exact(1);211    Rem,                     sym::rem,                 rem_trait,                  Target::Trait,          GenericRequirement::Exact(1);212    Neg,                     sym::neg,                 neg_trait,                  Target::Trait,          GenericRequirement::Exact(0);213    Not,                     sym::not,                 not_trait,                  Target::Trait,          GenericRequirement::Exact(0);214    BitXor,                  sym::bitxor,              bitxor_trait,               Target::Trait,          GenericRequirement::Exact(1);215    BitAnd,                  sym::bitand,              bitand_trait,               Target::Trait,          GenericRequirement::Exact(1);216    BitOr,                   sym::bitor,               bitor_trait,                Target::Trait,          GenericRequirement::Exact(1);217    Shl,                     sym::shl,                 shl_trait,                  Target::Trait,          GenericRequirement::Exact(1);218    Shr,                     sym::shr,                 shr_trait,                  Target::Trait,          GenericRequirement::Exact(1);219    AddAssign,               sym::add_assign,          add_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);220    SubAssign,               sym::sub_assign,          sub_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);221    MulAssign,               sym::mul_assign,          mul_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);222    DivAssign,               sym::div_assign,          div_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);223    RemAssign,               sym::rem_assign,          rem_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);224    BitXorAssign,            sym::bitxor_assign,       bitxor_assign_trait,        Target::Trait,          GenericRequirement::Exact(1);225    BitAndAssign,            sym::bitand_assign,       bitand_assign_trait,        Target::Trait,          GenericRequirement::Exact(1);226    BitOrAssign,             sym::bitor_assign,        bitor_assign_trait,         Target::Trait,          GenericRequirement::Exact(1);227    ShlAssign,               sym::shl_assign,          shl_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);228    ShrAssign,               sym::shr_assign,          shr_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);229    Index,                   sym::index,               index_trait,                Target::Trait,          GenericRequirement::Exact(1);230    IndexMut,                sym::index_mut,           index_mut_trait,            Target::Trait,          GenericRequirement::Exact(1);231232    UnsafeCell,              sym::unsafe_cell,         unsafe_cell_type,           Target::Struct,         GenericRequirement::None;233    CovariantUnsafeCell,   sym::covariant_unsafe_cell, covariant_unsafe_cell_type, Target::Struct,         GenericRequirement::Exact(1);234    UnsafePinned,            sym::unsafe_pinned,       unsafe_pinned_type,         Target::Struct,         GenericRequirement::None;235236    VaArgSafe,               sym::va_arg_safe,         va_arg_safe,                Target::Trait,          GenericRequirement::None;237    VaList,                  sym::va_list,             va_list,                    Target::Struct,         GenericRequirement::None;238239    Complex,                 sym::complex,             complex,                    Target::Struct,         GenericRequirement::Exact(1);240241    Deref,                   sym::deref,               deref_trait,                Target::Trait,          GenericRequirement::Exact(0);242    DerefMut,                sym::deref_mut,           deref_mut_trait,            Target::Trait,          GenericRequirement::Exact(0);243    DerefPure,               sym::deref_pure,          deref_pure_trait,           Target::Trait,          GenericRequirement::Exact(0);244    DerefTarget,             sym::deref_target,        deref_target,               Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::None;245    Receiver,                sym::receiver,            receiver_trait,             Target::Trait,          GenericRequirement::None;246    ReceiverTarget,          sym::receiver_target,     receiver_target,            Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::None;247    LegacyReceiver,          sym::legacy_receiver,     legacy_receiver_trait,      Target::Trait,          GenericRequirement::None;248249    Fn,                      kw::Fn,                   fn_trait,                   Target::Trait,          GenericRequirement::Exact(1);250    FnMut,                   sym::fn_mut,              fn_mut_trait,               Target::Trait,          GenericRequirement::Exact(1);251    FnOnce,                  sym::fn_once,             fn_once_trait,              Target::Trait,          GenericRequirement::Exact(1);252    FnStatic,                sym::fn_static,           fn_static_trait,            Target::Trait,          GenericRequirement::Exact(1);253254    AsyncFn,                 sym::async_fn,            async_fn_trait,             Target::Trait,          GenericRequirement::Exact(1);255    AsyncFnMut,              sym::async_fn_mut,        async_fn_mut_trait,         Target::Trait,          GenericRequirement::Exact(1);256    AsyncFnOnce,             sym::async_fn_once,       async_fn_once_trait,        Target::Trait,          GenericRequirement::Exact(1);257    AsyncFnOnceOutput,       sym::async_fn_once_output, async_fn_once_output,       Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::Exact(1);258    CallOnceFuture,          sym::call_once_future,    call_once_future,           Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::Exact(1);259    CallRefFuture,           sym::call_ref_future,     call_ref_future,            Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::Exact(2);260    AsyncFnKindHelper,       sym::async_fn_kind_helper, async_fn_kind_helper,      Target::Trait,          GenericRequirement::Exact(1);261    AsyncFnKindUpvars,       sym::async_fn_kind_upvars, async_fn_kind_upvars,      Target::AssocTy(AssocCtxt::Trait),          GenericRequirement::Exact(5);262263    FnOnceOutput,            sym::fn_once_output,      fn_once_output,             Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::None;264265    Iterator,                sym::iterator,            iterator_trait,             Target::Trait,          GenericRequirement::Exact(0);266    FusedIterator,           sym::fused_iterator,      fused_iterator_trait,       Target::Trait,          GenericRequirement::Exact(0);267    Future,                  sym::future_trait,        future_trait,               Target::Trait,          GenericRequirement::Exact(0);268    FutureOutput,            sym::future_output,       future_output,              Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::Exact(0);269    AsyncIterator,           sym::async_iterator,      async_iterator_trait,       Target::Trait,          GenericRequirement::Exact(0);270271    CoroutineState,          sym::coroutine_state,     coroutine_state,            Target::Enum,           GenericRequirement::None;272    Coroutine,               sym::coroutine,           coroutine_trait,            Target::Trait,          GenericRequirement::Exact(1);273    CoroutineReturn,         sym::coroutine_return,    coroutine_return,           Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::Exact(1);274    CoroutineYield,          sym::coroutine_yield,     coroutine_yield,            Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::Exact(1);275    CoroutineResume,         sym::coroutine_resume,    coroutine_resume,           Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;276277    Unpin,                   sym::unpin,               unpin_trait,                Target::Trait,          GenericRequirement::None;278    Pin,                     sym::pin,                 pin_type,                   Target::Struct,         GenericRequirement::None;279280    OrderingEnum,            sym::Ordering,            ordering_enum,              Target::Enum,           GenericRequirement::Exact(0);281    PartialEq,               sym::eq,                  eq_trait,                   Target::Trait,          GenericRequirement::Exact(1);282    PartialOrd,              sym::partial_ord,         partial_ord_trait,          Target::Trait,          GenericRequirement::Exact(1);283    CVoid,                   sym::c_void,              c_void,                     Target::Enum,           GenericRequirement::None;284285    Type,                    sym::type_info,           type_struct,                Target::Struct,         GenericRequirement::None;286    TypeGeneric,             sym::type_info_generic,   type_generic,               Target::Enum,         GenericRequirement::None;287    TypeId,                  sym::type_id,             type_id,                    Target::Struct,         GenericRequirement::None;288289    // A number of panic-related lang items. The `panic` item corresponds to divide-by-zero and290    // various panic cases with `match`. The `panic_bounds_check` item is for indexing arrays.291    //292    // The `begin_unwind` lang item has a predefined symbol name and is sort of a "weak lang item"293    // in the sense that a crate is not required to have it defined to use it, but a final product294    // is required to define it somewhere. Additionally, there are restrictions on crates that use295    // a weak lang item, but do not have it defined.296    Panic,                   sym::panic,               panic_fn,                   Target::Fn,             GenericRequirement::Exact(0);297    PanicNounwind,           sym::panic_nounwind,      panic_nounwind,             Target::Fn,             GenericRequirement::Exact(0);298    PanicFmt,                sym::panic_fmt,           panic_fmt,                  Target::Fn,             GenericRequirement::None;299    PanicDisplay,            sym::panic_display,       panic_display,              Target::Fn,             GenericRequirement::None;300    ConstPanicFmt,           sym::const_panic_fmt,     const_panic_fmt,            Target::Fn,             GenericRequirement::None;301    PanicBoundsCheck,        sym::panic_bounds_check,  panic_bounds_check_fn,      Target::Fn,             GenericRequirement::Exact(0);302    PanicMisalignedPointerDereference, sym::panic_misaligned_pointer_dereference, panic_misaligned_pointer_dereference_fn, Target::Fn, GenericRequirement::Exact(0);303    PanicInfo,               sym::panic_info,          panic_info,                 Target::Struct,         GenericRequirement::None;304    PanicLocation,           sym::panic_location,      panic_location,             Target::Struct,         GenericRequirement::None;305    PanicImpl,               sym::panic_impl,          panic_impl,                 Target::ForeignFn,      GenericRequirement::None;306    PanicCannotUnwind,       sym::panic_cannot_unwind, panic_cannot_unwind,        Target::Fn,             GenericRequirement::Exact(0);307    PanicInCleanup,          sym::panic_in_cleanup,    panic_in_cleanup,           Target::Fn,             GenericRequirement::Exact(0);308    /// Constant panic messages, used for codegen of MIR asserts.309    PanicAddOverflow,        sym::panic_const_add_overflow, panic_const_add_overflow, Target::Fn, GenericRequirement::None;310    PanicSubOverflow,        sym::panic_const_sub_overflow, panic_const_sub_overflow, Target::Fn, GenericRequirement::None;311    PanicMulOverflow,        sym::panic_const_mul_overflow, panic_const_mul_overflow, Target::Fn, GenericRequirement::None;312    PanicDivOverflow,        sym::panic_const_div_overflow, panic_const_div_overflow, Target::Fn, GenericRequirement::None;313    PanicRemOverflow,        sym::panic_const_rem_overflow, panic_const_rem_overflow, Target::Fn, GenericRequirement::None;314    PanicNegOverflow,        sym::panic_const_neg_overflow, panic_const_neg_overflow, Target::Fn, GenericRequirement::None;315    PanicShrOverflow,        sym::panic_const_shr_overflow, panic_const_shr_overflow, Target::Fn, GenericRequirement::None;316    PanicShlOverflow,        sym::panic_const_shl_overflow, panic_const_shl_overflow, Target::Fn, GenericRequirement::None;317    PanicDivZero,            sym::panic_const_div_by_zero, panic_const_div_by_zero, Target::Fn, GenericRequirement::None;318    PanicRemZero,            sym::panic_const_rem_by_zero, panic_const_rem_by_zero, Target::Fn, GenericRequirement::None;319    PanicCoroutineResumed, sym::panic_const_coroutine_resumed, panic_const_coroutine_resumed, Target::Fn, GenericRequirement::None;320    PanicAsyncFnResumed, sym::panic_const_async_fn_resumed, panic_const_async_fn_resumed, Target::Fn, GenericRequirement::None;321    PanicAsyncGenFnResumed, sym::panic_const_async_gen_fn_resumed, panic_const_async_gen_fn_resumed, Target::Fn, GenericRequirement::None;322    PanicGenFnNone, sym::panic_const_gen_fn_none, panic_const_gen_fn_none, Target::Fn, GenericRequirement::None;323    PanicCoroutineResumedPanic, sym::panic_const_coroutine_resumed_panic, panic_const_coroutine_resumed_panic, Target::Fn, GenericRequirement::None;324    PanicAsyncFnResumedPanic, sym::panic_const_async_fn_resumed_panic, panic_const_async_fn_resumed_panic, Target::Fn, GenericRequirement::None;325    PanicAsyncGenFnResumedPanic, sym::panic_const_async_gen_fn_resumed_panic, panic_const_async_gen_fn_resumed_panic, Target::Fn, GenericRequirement::None;326    PanicGenFnNonePanic, sym::panic_const_gen_fn_none_panic, panic_const_gen_fn_none_panic, Target::Fn, GenericRequirement::None;327    PanicNullPointerDereference, sym::panic_null_pointer_dereference, panic_null_pointer_dereference, Target::Fn, GenericRequirement::None;328    PanicNullReferenceConstructed, sym::panic_null_reference_constructed, panic_null_reference_constructed, Target::Fn, GenericRequirement::None;329    PanicInvalidEnumConstruction, sym::panic_invalid_enum_construction, panic_invalid_enum_construction, Target::Fn, GenericRequirement::None;330    PanicCoroutineResumedDrop, sym::panic_const_coroutine_resumed_drop, panic_const_coroutine_resumed_drop, Target::Fn, GenericRequirement::None;331    PanicAsyncFnResumedDrop, sym::panic_const_async_fn_resumed_drop, panic_const_async_fn_resumed_drop, Target::Fn, GenericRequirement::None;332    PanicAsyncGenFnResumedDrop, sym::panic_const_async_gen_fn_resumed_drop, panic_const_async_gen_fn_resumed_drop, Target::Fn, GenericRequirement::None;333    PanicGenFnNoneDrop, sym::panic_const_gen_fn_none_drop, panic_const_gen_fn_none_drop, Target::Fn, GenericRequirement::None;334    /// libstd panic entry point. Necessary for const eval to be able to catch it335    BeginPanic,              sym::begin_panic,         begin_panic_fn,             Target::Fn,             GenericRequirement::None;336337    // Lang items needed for `format_args!()`.338    FormatArgument,          sym::format_argument,     format_argument,            Target::Struct,         GenericRequirement::None;339    FormatArguments,         sym::format_arguments,    format_arguments,           Target::Struct,         GenericRequirement::None;340341    // Compiler-generated drop glue function, aka `core::ptr::drop_glue`342    DropGlue,                sym::drop_glue,           drop_glue_fn,               Target::Fn,             GenericRequirement::Exact(1);343    AllocLayout,             sym::alloc_layout,        alloc_layout,               Target::Struct,         GenericRequirement::None;344345    /// For all binary crates without `#![no_main]`, Rust will generate a "main" function.346    /// The exact name and signature are target-dependent. The "main" function will invoke347    /// this lang item, passing it the `argc` and `argv` (or null, if those don't exist348    /// on the current target) as well as the user-defined `fn main` from the binary crate.349    Start,                   sym::start,               start_fn,                   Target::Fn,             GenericRequirement::Exact(1);350351    EhPersonality,           sym::eh_personality,      eh_personality,             Target::Fn,             GenericRequirement::None;352353    // Profiling markers for move/copy operations (used by -Z annotate-moves)354    CompilerMove,            sym::compiler_move,       compiler_move_fn,           Target::Fn,             GenericRequirement::Exact(2);355    CompilerCopy,            sym::compiler_copy,       compiler_copy_fn,           Target::Fn,             GenericRequirement::Exact(2);356357    OwnedBox,                sym::owned_box,           owned_box,                  Target::Struct,         GenericRequirement::Minimum(1);358    GlobalAlloc,             sym::global_alloc_ty,     global_alloc_ty,            Target::Struct,         GenericRequirement::None;359360    PhantomData,             sym::phantom_data,        phantom_data,               Target::Struct,         GenericRequirement::Exact(1);361362    ManuallyDrop,            sym::manually_drop,       manually_drop,              Target::Struct,         GenericRequirement::Exact(1);363    MaybeDangling,           sym::maybe_dangling,      maybe_dangling,             Target::Struct,         GenericRequirement::Exact(1);364    BikeshedGuaranteedNoDrop, sym::bikeshed_guaranteed_no_drop, bikeshed_guaranteed_no_drop, Target::Trait, GenericRequirement::Exact(0);365366    MaybeUninit,             sym::maybe_uninit,        maybe_uninit,               Target::Union,          GenericRequirement::None;367368    Termination,             sym::termination,         termination,                Target::Trait,          GenericRequirement::None;369370    Try,                     sym::Try,                 try_trait,                  Target::Trait,          GenericRequirement::None;371372    Tuple,                   sym::tuple_trait,         tuple_trait,                Target::Trait,          GenericRequirement::Exact(0);373374    SliceLen,                sym::slice_len_fn,        slice_len_fn,               Target::Method(MethodKind::Inherent), GenericRequirement::None;375376    // Language items from AST lowering377    TryTraitFromResidual,    sym::from_residual,       from_residual_fn,           Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;378    TryTraitFromOutput,      sym::from_output,         from_output_fn,             Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;379    TryTraitBranch,          sym::branch,              branch_fn,                  Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;380    TryTraitFromYeet,        sym::from_yeet,           from_yeet_fn,               Target::Fn,             GenericRequirement::None;381    ResidualIntoTryType,     sym::into_try_type,       into_try_type_fn,           Target::Fn,             GenericRequirement::None;382383    CoercePointeeValidated, sym::coerce_pointee_validated, coerce_pointee_validated_trait, Target::Trait,     GenericRequirement::Exact(0);384385    ConstParamTy,            sym::const_param_ty,      const_param_ty_trait,       Target::Trait,          GenericRequirement::Exact(0);386387    Poll,                    sym::Poll,                poll,                       Target::Enum,           GenericRequirement::None;388    PollReady,               sym::Ready,               poll_ready_variant,         Target::Variant,        GenericRequirement::None;389    PollPending,             sym::Pending,             poll_pending_variant,       Target::Variant,        GenericRequirement::None;390391    AsyncGenReady,           sym::AsyncGenReady,       async_gen_ready,            Target::Method(MethodKind::Inherent), GenericRequirement::Exact(1);392    AsyncGenPending,         sym::AsyncGenPending,     async_gen_pending,          Target::AssocConst(AssocCtxt::Impl { of_trait: false }), GenericRequirement::Exact(1);393    AsyncGenFinished,        sym::AsyncGenFinished,    async_gen_finished,         Target::AssocConst(AssocCtxt::Impl { of_trait: false }), GenericRequirement::Exact(1);394395    // FIXME(swatinem): the following lang items are used for async lowering and396    // should become obsolete eventually.397    ResumeTy,                sym::ResumeTy,            resume_ty,                  Target::Struct,         GenericRequirement::None;398    GetContext,              sym::get_context,         get_context_fn,             Target::Fn,             GenericRequirement::None;399400    Context,                 sym::Context,             context,                    Target::Struct,         GenericRequirement::None;401    FuturePoll,              sym::poll,                future_poll_fn,             Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;402403    AsyncIteratorPollNext,   sym::async_iterator_poll_next, async_iterator_poll_next, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::Exact(0);404    IntoAsyncIterIntoIter,   sym::into_async_iter_into_iter, into_async_iter_into_iter, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::Exact(0);405406    Option,                  sym::Option,              option_type,                Target::Enum,           GenericRequirement::None;407    OptionSome,              sym::Some,                option_some_variant,        Target::Variant,        GenericRequirement::None;408    OptionNone,              sym::None,                option_none_variant,        Target::Variant,        GenericRequirement::None;409410    ResultOk,                sym::Ok,                  result_ok_variant,          Target::Variant,        GenericRequirement::None;411    ResultErr,               sym::Err,                 result_err_variant,         Target::Variant,        GenericRequirement::None;412413    ControlFlowContinue,     sym::Continue,            cf_continue_variant,        Target::Variant,        GenericRequirement::None;414    ControlFlowBreak,        sym::Break,               cf_break_variant,           Target::Variant,        GenericRequirement::None;415416    IntoFutureIntoFuture,    sym::into_future,         into_future_fn,             Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;417    IntoIterIntoIter,        sym::into_iter,           into_iter_fn,               Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;418    IteratorNext,            sym::next,                next_fn,                    Target::Method(MethodKind::Trait { body: false}), GenericRequirement::None;419420    PinNewUnchecked,         sym::new_unchecked,       new_unchecked_fn,           Target::Method(MethodKind::Inherent), GenericRequirement::None;421422    RangeFrom,               sym::RangeFrom,           range_from_struct,          Target::Struct,         GenericRequirement::None;423    RangeFull,               sym::RangeFull,           range_full_struct,          Target::Struct,         GenericRequirement::None;424    RangeInclusiveStruct,    sym::RangeInclusive,      range_inclusive_struct,     Target::Struct,         GenericRequirement::None;425    RangeInclusiveNew,       sym::range_inclusive_new, range_inclusive_new_method, Target::Method(MethodKind::Inherent), GenericRequirement::None;426    Range,                   sym::Range,               range_struct,               Target::Struct,         GenericRequirement::None;427    RangeToInclusive,        sym::RangeToInclusive,    range_to_inclusive_struct,  Target::Struct,         GenericRequirement::None;428    RangeTo,                 sym::RangeTo,             range_to_struct,            Target::Struct,         GenericRequirement::None;429    RangeMax,                sym::RangeMax,            range_max,                  Target::AssocConst(AssocCtxt::Trait),     GenericRequirement::Exact(0);430    RangeMin,                sym::RangeMin,            range_min,                  Target::AssocConst(AssocCtxt::Trait),     GenericRequirement::Exact(0);431    RangeSub,                sym::RangeSub,            range_sub,                  Target::Method(MethodKind::Trait { body: false }),     GenericRequirement::Exact(0);432433    // `new_range` types that are `Copy + IntoIterator`434    RangeFromCopy,           sym::RangeFromCopy,       range_from_copy_struct,     Target::Struct,         GenericRequirement::None;435    RangeCopy,               sym::RangeCopy,           range_copy_struct,          Target::Struct,         GenericRequirement::None;436    RangeInclusiveCopy,      sym::RangeInclusiveCopy,  range_inclusive_copy_struct, Target::Struct,         GenericRequirement::None;437    RangeToInclusiveCopy,    sym::RangeToInclusiveCopy,     range_to_inclusive_copy_struct, Target::Struct, GenericRequirement::None;438439    String,                  sym::String,              string,                     Target::Struct,         GenericRequirement::None;440    CStr,                    sym::CStr,                c_str,                      Target::Struct,         GenericRequirement::None;441442    // Experimental lang items for implementing contract pre- and post-condition checking.443    ContractBuildCheckEnsures, sym::contract_build_check_ensures, contract_build_check_ensures_fn, Target::Fn, GenericRequirement::None;444    ContractCheckRequires,     sym::contract_check_requires,      contract_check_requires_fn,      Target::Fn, GenericRequirement::None;445446    // Experimental lang items for `MCP: Low level components for async drop`(https://github.com/rust-lang/compiler-team/issues/727)447    DefaultTrait4,           sym::default_trait4,      default_trait4_trait,       Target::Trait,          GenericRequirement::None;448    DefaultTrait3,           sym::default_trait3,      default_trait3_trait,       Target::Trait,          GenericRequirement::None;449    DefaultTrait2,           sym::default_trait2,      default_trait2_trait,       Target::Trait,          GenericRequirement::None;450    DefaultTrait1,           sym::default_trait1,      default_trait1_trait,       Target::Trait,          GenericRequirement::None;451452    ContractCheckEnsures,     sym::contract_check_ensures,      contract_check_ensures_fn,      Target::Fn, GenericRequirement::None;453454    // Reborrowing related lang-items455    Reborrow,                sym::reborrow,            reborrow,                   Target::Trait,          GenericRequirement::Exact(0);456    CoerceShared,            sym::coerce_shared,       coerce_shared,              Target::Trait,          GenericRequirement::Exact(1);457458    // Field representing types.459    FieldRepresentingType,   sym::field_representing_type, field_representing_type,    Target::Struct,         GenericRequirement::Exact(3);460    Field,                   sym::field,                   field,                      Target::Trait,          GenericRequirement::Exact(0);461    FieldBase,               sym::field_base,              field_base,                 Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::Exact(0);462    FieldType,               sym::field_type,              field_type,                 Target::AssocTy(AssocCtxt::Trait),        GenericRequirement::Exact(0);463    FieldOffset,             sym::field_offset,            field_offset,               Target::AssocConst(AssocCtxt::Trait),     GenericRequirement::Exact(0);464465    // Used to fallback `{float}` to `f32` when `f32: From<{float}>`466    From,                    sym::From,                from_trait,                 Target::Trait,          GenericRequirement::Exact(1);467    FromFn,                  sym::from,                from_fn,                    Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;468}469470/// The requirement imposed on the generics of a lang item471pub enum GenericRequirement {472    /// No restriction on the generics473    None,474    /// A minimum number of generics that is demanded on a lang item475    Minimum(usize),476    /// The number of generics must match precisely as stipulated477    Exact(usize),478}479480pub static FN_TRAITS: &'static [LangItem] = &[LangItem::Fn, LangItem::FnMut, LangItem::FnOnce];481482pub static OPERATORS: &'static [LangItem] = &[483    LangItem::Add,484    LangItem::Sub,485    LangItem::Mul,486    LangItem::Div,487    LangItem::Rem,488    LangItem::Neg,489    LangItem::Not,490    LangItem::BitXor,491    LangItem::BitAnd,492    LangItem::BitOr,493    LangItem::Shl,494    LangItem::Shr,495    LangItem::AddAssign,496    LangItem::SubAssign,497    LangItem::MulAssign,498    LangItem::DivAssign,499    LangItem::RemAssign,500    LangItem::BitXorAssign,501    LangItem::BitAndAssign,502    LangItem::BitOrAssign,503    LangItem::ShlAssign,504    LangItem::ShrAssign,505    LangItem::Index,506    LangItem::IndexMut,507    LangItem::PartialEq,508    LangItem::PartialOrd,509];510511pub static BINARY_OPERATORS: &'static [LangItem] = &[512    LangItem::Add,513    LangItem::Sub,514    LangItem::Mul,515    LangItem::Div,516    LangItem::Rem,517    LangItem::BitXor,518    LangItem::BitAnd,519    LangItem::BitOr,520    LangItem::Shl,521    LangItem::Shr,522    LangItem::AddAssign,523    LangItem::SubAssign,524    LangItem::MulAssign,525    LangItem::DivAssign,526    LangItem::RemAssign,527    LangItem::BitXorAssign,528    LangItem::BitAndAssign,529    LangItem::BitOrAssign,530    LangItem::ShlAssign,531    LangItem::ShrAssign,532    LangItem::Index,533    LangItem::IndexMut,534    LangItem::PartialEq,535    LangItem::PartialOrd,536];