//! Defines language items. //! //! Language items are items that represent concepts intrinsic to the language //! itself. Examples are: //! //! * Traits that specify "kinds"; e.g., `Sync`, `Send`. //! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`. //! * Functions called by the compiler itself. use crate::def_id::DefId; use crate::{MethodKind, Target}; use rustc_ast as ast; use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; use rustc_macros::HashStable_Generic; use rustc_span::symbol::{kw, sym, Symbol}; use rustc_span::Span; /// All of the language items, defined or not. /// Defined lang items can come from the current crate or its dependencies. #[derive(HashStable_Generic, Debug)] pub struct LanguageItems { /// Mappings from lang items to their possibly found [`DefId`]s. /// The index corresponds to the order in [`LangItem`]. items: [Option; std::mem::variant_count::()], /// Lang items that were not found during collection. pub missing: Vec, } impl LanguageItems { /// Construct an empty collection of lang items and no missing ones. pub fn new() -> Self { Self { items: [None; std::mem::variant_count::()], missing: Vec::new() } } pub fn get(&self, item: LangItem) -> Option { self.items[item as usize] } pub fn set(&mut self, item: LangItem, def_id: DefId) { self.items[item as usize] = Some(def_id); } pub fn iter(&self) -> impl Iterator + '_ { self.items .iter() .enumerate() .filter_map(|(i, id)| id.map(|id| (LangItem::from_u32(i as u32).unwrap(), id))) } } // The actual lang items defined come at the end of this file in one handy table. // So you probably just want to nip down to the end. macro_rules! language_item_table { ( $( $(#[$attr:meta])* $variant:ident, $module:ident :: $name:ident, $method:ident, $target:expr, $generics:expr; )* ) => { enum_from_u32! { /// A representation of all the valid language items in Rust. #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Encodable, Decodable)] pub enum LangItem { $( #[doc = concat!("The `", stringify!($name), "` lang item.")] /// $(#[$attr])* $variant, )* } } impl LangItem { /// Returns the `name` symbol in `#[lang = "$name"]`. /// For example, [`LangItem::PartialEq`]`.name()` /// would result in [`sym::eq`] since it is `#[lang = "eq"]`. pub fn name(self) -> Symbol { match self { $( LangItem::$variant => $module::$name, )* } } /// Opposite of [`LangItem::name`] pub fn from_name(name: Symbol) -> Option { match name { $( $module::$name => Some(LangItem::$variant), )* _ => None, } } /// Returns the name of the `LangItem` enum variant. // This method is used by Clippy for internal lints. pub fn variant_name(self) -> &'static str { match self { $( LangItem::$variant => stringify!($variant), )* } } pub fn target(self) -> Target { match self { $( LangItem::$variant => $target, )* } } pub fn required_generics(&self) -> GenericRequirement { match self { $( LangItem::$variant => $generics, )* } } } impl LanguageItems { $( #[doc = concat!("Returns the [`DefId`] of the `", stringify!($name), "` lang item if it is defined.")] pub fn $method(&self) -> Option { self.items[LangItem::$variant as usize] } )* } } } impl HashStable for LangItem { fn hash_stable(&self, _: &mut CTX, hasher: &mut StableHasher) { ::std::hash::Hash::hash(self, hasher); } } /// Extracts the first `lang = "$name"` out of a list of attributes. /// The `#[panic_handler]` attribute is also extracted out when found. pub fn extract(attrs: &[ast::Attribute]) -> Option<(Symbol, Span)> { attrs.iter().find_map(|attr| { Some(match attr { _ if attr.has_name(sym::lang) => (attr.value_str()?, attr.span), _ if attr.has_name(sym::panic_handler) => (sym::panic_impl, attr.span), _ => return None, }) }) } language_item_table! { // Variant name, Name, Getter method name, Target Generic requirements; Sized, sym::sized, sized_trait, Target::Trait, GenericRequirement::Exact(0); Unsize, sym::unsize, unsize_trait, Target::Trait, GenericRequirement::Minimum(1); /// Trait injected by `#[derive(PartialEq)]`, (i.e. "Partial EQ"). StructuralPeq, sym::structural_peq, structural_peq_trait, Target::Trait, GenericRequirement::None; /// Trait injected by `#[derive(Eq)]`, (i.e. "Total EQ"; no, I will not apologize). StructuralTeq, sym::structural_teq, structural_teq_trait, Target::Trait, GenericRequirement::None; Copy, sym::copy, copy_trait, Target::Trait, GenericRequirement::Exact(0); Clone, sym::clone, clone_trait, Target::Trait, GenericRequirement::None; Sync, sym::sync, sync_trait, Target::Trait, GenericRequirement::Exact(0); DiscriminantKind, sym::discriminant_kind, discriminant_kind_trait, Target::Trait, GenericRequirement::None; /// The associated item of the [`DiscriminantKind`] trait. Discriminant, sym::discriminant_type, discriminant_type, Target::AssocTy, GenericRequirement::None; PointeeTrait, sym::pointee_trait, pointee_trait, Target::Trait, GenericRequirement::None; Metadata, sym::metadata_type, metadata_type, Target::AssocTy, GenericRequirement::None; DynMetadata, sym::dyn_metadata, dyn_metadata, Target::Struct, GenericRequirement::None; Freeze, sym::freeze, freeze_trait, Target::Trait, GenericRequirement::Exact(0); FnPtrTrait, sym::fn_ptr_trait, fn_ptr_trait, Target::Trait, GenericRequirement::Exact(0); FnPtrAddr, sym::fn_ptr_addr, fn_ptr_addr, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; Drop, sym::drop, drop_trait, Target::Trait, GenericRequirement::None; Destruct, sym::destruct, destruct_trait, Target::Trait, GenericRequirement::None; CoerceUnsized, sym::coerce_unsized, coerce_unsized_trait, Target::Trait, GenericRequirement::Minimum(1); DispatchFromDyn, sym::dispatch_from_dyn, dispatch_from_dyn_trait, Target::Trait, GenericRequirement::Minimum(1); // language items relating to transmutability TransmuteOpts, sym::transmute_opts, transmute_opts, Target::Struct, GenericRequirement::Exact(0); TransmuteTrait, sym::transmute_trait, transmute_trait, Target::Trait, GenericRequirement::Exact(3); Add, sym::add, add_trait, Target::Trait, GenericRequirement::Exact(1); Sub, sym::sub, sub_trait, Target::Trait, GenericRequirement::Exact(1); Mul, sym::mul, mul_trait, Target::Trait, GenericRequirement::Exact(1); Div, sym::div, div_trait, Target::Trait, GenericRequirement::Exact(1); Rem, sym::rem, rem_trait, Target::Trait, GenericRequirement::Exact(1); Neg, sym::neg, neg_trait, Target::Trait, GenericRequirement::Exact(0); Not, sym::not, not_trait, Target::Trait, GenericRequirement::Exact(0); BitXor, sym::bitxor, bitxor_trait, Target::Trait, GenericRequirement::Exact(1); BitAnd, sym::bitand, bitand_trait, Target::Trait, GenericRequirement::Exact(1); BitOr, sym::bitor, bitor_trait, Target::Trait, GenericRequirement::Exact(1); Shl, sym::shl, shl_trait, Target::Trait, GenericRequirement::Exact(1); Shr, sym::shr, shr_trait, Target::Trait, GenericRequirement::Exact(1); AddAssign, sym::add_assign, add_assign_trait, Target::Trait, GenericRequirement::Exact(1); SubAssign, sym::sub_assign, sub_assign_trait, Target::Trait, GenericRequirement::Exact(1); MulAssign, sym::mul_assign, mul_assign_trait, Target::Trait, GenericRequirement::Exact(1); DivAssign, sym::div_assign, div_assign_trait, Target::Trait, GenericRequirement::Exact(1); RemAssign, sym::rem_assign, rem_assign_trait, Target::Trait, GenericRequirement::Exact(1); BitXorAssign, sym::bitxor_assign, bitxor_assign_trait, Target::Trait, GenericRequirement::Exact(1); BitAndAssign, sym::bitand_assign, bitand_assign_trait, Target::Trait, GenericRequirement::Exact(1); BitOrAssign, sym::bitor_assign, bitor_assign_trait, Target::Trait, GenericRequirement::Exact(1); ShlAssign, sym::shl_assign, shl_assign_trait, Target::Trait, GenericRequirement::Exact(1); ShrAssign, sym::shr_assign, shr_assign_trait, Target::Trait, GenericRequirement::Exact(1); Index, sym::index, index_trait, Target::Trait, GenericRequirement::Exact(1); IndexMut, sym::index_mut, index_mut_trait, Target::Trait, GenericRequirement::Exact(1); UnsafeCell, sym::unsafe_cell, unsafe_cell_type, Target::Struct, GenericRequirement::None; VaList, sym::va_list, va_list, Target::Struct, GenericRequirement::None; Deref, sym::deref, deref_trait, Target::Trait, GenericRequirement::Exact(0); DerefMut, sym::deref_mut, deref_mut_trait, Target::Trait, GenericRequirement::Exact(0); DerefTarget, sym::deref_target, deref_target, Target::AssocTy, GenericRequirement::None; Receiver, sym::receiver, receiver_trait, Target::Trait, GenericRequirement::None; Fn, kw::Fn, fn_trait, Target::Trait, GenericRequirement::Exact(1); FnMut, sym::fn_mut, fn_mut_trait, Target::Trait, GenericRequirement::Exact(1); FnOnce, sym::fn_once, fn_once_trait, Target::Trait, GenericRequirement::Exact(1); FnOnceOutput, sym::fn_once_output, fn_once_output, Target::AssocTy, GenericRequirement::None; Future, sym::future_trait, future_trait, Target::Trait, GenericRequirement::Exact(0); GeneratorState, sym::generator_state, gen_state, Target::Enum, GenericRequirement::None; Generator, sym::generator, gen_trait, Target::Trait, GenericRequirement::Minimum(1); Unpin, sym::unpin, unpin_trait, Target::Trait, GenericRequirement::None; Pin, sym::pin, pin_type, Target::Struct, GenericRequirement::None; PartialEq, sym::eq, eq_trait, Target::Trait, GenericRequirement::Exact(1); PartialOrd, sym::partial_ord, partial_ord_trait, Target::Trait, GenericRequirement::Exact(1); CVoid, sym::c_void, c_void, Target::Enum, GenericRequirement::None; // A number of panic-related lang items. The `panic` item corresponds to divide-by-zero and // various panic cases with `match`. The `panic_bounds_check` item is for indexing arrays. // // The `begin_unwind` lang item has a predefined symbol name and is sort of a "weak lang item" // in the sense that a crate is not required to have it defined to use it, but a final product // is required to define it somewhere. Additionally, there are restrictions on crates that use // a weak lang item, but do not have it defined. Panic, sym::panic, panic_fn, Target::Fn, GenericRequirement::Exact(0); PanicNounwind, sym::panic_nounwind, panic_nounwind, Target::Fn, GenericRequirement::Exact(0); PanicFmt, sym::panic_fmt, panic_fmt, Target::Fn, GenericRequirement::None; PanicDisplay, sym::panic_display, panic_display, Target::Fn, GenericRequirement::None; ConstPanicFmt, sym::const_panic_fmt, const_panic_fmt, Target::Fn, GenericRequirement::None; PanicBoundsCheck, sym::panic_bounds_check, panic_bounds_check_fn, Target::Fn, GenericRequirement::Exact(0); PanicMisalignedPointerDereference, sym::panic_misaligned_pointer_dereference, panic_misaligned_pointer_dereference_fn, Target::Fn, GenericRequirement::Exact(0); PanicInfo, sym::panic_info, panic_info, Target::Struct, GenericRequirement::None; PanicLocation, sym::panic_location, panic_location, Target::Struct, GenericRequirement::None; PanicImpl, sym::panic_impl, panic_impl, Target::Fn, GenericRequirement::None; PanicCannotUnwind, sym::panic_cannot_unwind, panic_cannot_unwind, Target::Fn, GenericRequirement::Exact(0); PanicInCleanup, sym::panic_in_cleanup, panic_in_cleanup, Target::Fn, GenericRequirement::Exact(0); /// libstd panic entry point. Necessary for const eval to be able to catch it BeginPanic, sym::begin_panic, begin_panic_fn, Target::Fn, GenericRequirement::None; // Lang items needed for `format_args!()`. FormatAlignment, sym::format_alignment, format_alignment, Target::Enum, GenericRequirement::None; FormatArgument, sym::format_argument, format_argument, Target::Struct, GenericRequirement::None; FormatArguments, sym::format_arguments, format_arguments, Target::Struct, GenericRequirement::None; FormatCount, sym::format_count, format_count, Target::Enum, GenericRequirement::None; FormatPlaceholder, sym::format_placeholder, format_placeholder, Target::Struct, GenericRequirement::None; FormatUnsafeArg, sym::format_unsafe_arg, format_unsafe_arg, Target::Struct, GenericRequirement::None; ExchangeMalloc, sym::exchange_malloc, exchange_malloc_fn, Target::Fn, GenericRequirement::None; DropInPlace, sym::drop_in_place, drop_in_place_fn, Target::Fn, GenericRequirement::Minimum(1); AllocLayout, sym::alloc_layout, alloc_layout, Target::Struct, GenericRequirement::None; Start, sym::start, start_fn, Target::Fn, GenericRequirement::Exact(1); EhPersonality, sym::eh_personality, eh_personality, Target::Fn, GenericRequirement::None; EhCatchTypeinfo, sym::eh_catch_typeinfo, eh_catch_typeinfo, Target::Static, GenericRequirement::None; OwnedBox, sym::owned_box, owned_box, Target::Struct, GenericRequirement::Minimum(1); // Experimental language item for Miri PtrUnique, sym::ptr_unique, ptr_unique, Target::Struct, GenericRequirement::Exact(1); PhantomData, sym::phantom_data, phantom_data, Target::Struct, GenericRequirement::Exact(1); ManuallyDrop, sym::manually_drop, manually_drop, Target::Struct, GenericRequirement::None; MaybeUninit, sym::maybe_uninit, maybe_uninit, Target::Union, GenericRequirement::None; /// Align offset for stride != 1; must not panic. AlignOffset, sym::align_offset, align_offset_fn, Target::Fn, GenericRequirement::None; Termination, sym::termination, termination, Target::Trait, GenericRequirement::None; Try, sym::Try, try_trait, Target::Trait, GenericRequirement::None; Tuple, sym::tuple_trait, tuple_trait, Target::Trait, GenericRequirement::Exact(0); SliceLen, sym::slice_len_fn, slice_len_fn, Target::Method(MethodKind::Inherent), GenericRequirement::None; // Language items from AST lowering TryTraitFromResidual, sym::from_residual, from_residual_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; TryTraitFromOutput, sym::from_output, from_output_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; TryTraitBranch, sym::branch, branch_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; TryTraitFromYeet, sym::from_yeet, from_yeet_fn, Target::Fn, GenericRequirement::None; PointerLike, sym::pointer_like, pointer_like, Target::Trait, GenericRequirement::Exact(0); ConstParamTy, sym::const_param_ty, const_param_ty_trait, Target::Trait, GenericRequirement::Exact(0); Poll, sym::Poll, poll, Target::Enum, GenericRequirement::None; PollReady, sym::Ready, poll_ready_variant, Target::Variant, GenericRequirement::None; PollPending, sym::Pending, poll_pending_variant, Target::Variant, GenericRequirement::None; // FIXME(swatinem): the following lang items are used for async lowering and // should become obsolete eventually. ResumeTy, sym::ResumeTy, resume_ty, Target::Struct, GenericRequirement::None; GetContext, sym::get_context, get_context_fn, Target::Fn, GenericRequirement::None; Context, sym::Context, context, Target::Struct, GenericRequirement::None; FuturePoll, sym::poll, future_poll_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; Option, sym::Option, option_type, Target::Enum, GenericRequirement::None; OptionSome, sym::Some, option_some_variant, Target::Variant, GenericRequirement::None; OptionNone, sym::None, option_none_variant, Target::Variant, GenericRequirement::None; ResultOk, sym::Ok, result_ok_variant, Target::Variant, GenericRequirement::None; ResultErr, sym::Err, result_err_variant, Target::Variant, GenericRequirement::None; ControlFlowContinue, sym::Continue, cf_continue_variant, Target::Variant, GenericRequirement::None; ControlFlowBreak, sym::Break, cf_break_variant, Target::Variant, GenericRequirement::None; IntoFutureIntoFuture, sym::into_future, into_future_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; IntoIterIntoIter, sym::into_iter, into_iter_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; IteratorNext, sym::next, next_fn, Target::Method(MethodKind::Trait { body: false}), GenericRequirement::None; PinNewUnchecked, sym::new_unchecked, new_unchecked_fn, Target::Method(MethodKind::Inherent), GenericRequirement::None; RangeFrom, sym::RangeFrom, range_from_struct, Target::Struct, GenericRequirement::None; RangeFull, sym::RangeFull, range_full_struct, Target::Struct, GenericRequirement::None; RangeInclusiveStruct, sym::RangeInclusive, range_inclusive_struct, Target::Struct, GenericRequirement::None; RangeInclusiveNew, sym::range_inclusive_new, range_inclusive_new_method, Target::Method(MethodKind::Inherent), GenericRequirement::None; Range, sym::Range, range_struct, Target::Struct, GenericRequirement::None; RangeToInclusive, sym::RangeToInclusive, range_to_inclusive_struct, Target::Struct, GenericRequirement::None; RangeTo, sym::RangeTo, range_to_struct, Target::Struct, GenericRequirement::None; String, sym::String, string, Target::Struct, GenericRequirement::None; CStr, sym::CStr, c_str, Target::Struct, GenericRequirement::None; } pub enum GenericRequirement { None, Minimum(usize), Exact(usize), } pub static FN_TRAITS: &'static [LangItem] = &[LangItem::Fn, LangItem::FnMut, LangItem::FnOnce]; pub static OPERATORS: &'static [LangItem] = &[ LangItem::Add, LangItem::Sub, LangItem::Mul, LangItem::Div, LangItem::Rem, LangItem::Neg, LangItem::Not, LangItem::BitXor, LangItem::BitAnd, LangItem::BitOr, LangItem::Shl, LangItem::Shr, LangItem::AddAssign, LangItem::SubAssign, LangItem::MulAssign, LangItem::DivAssign, LangItem::RemAssign, LangItem::BitXorAssign, LangItem::BitAndAssign, LangItem::BitOrAssign, LangItem::ShlAssign, LangItem::ShrAssign, LangItem::Index, LangItem::IndexMut, LangItem::PartialEq, LangItem::PartialOrd, ];