//! 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. pub use self::LangItem::*; use crate::def_id::DefId; use crate::Target; use rustc_ast::ast; use rustc_data_structures::fx::FxHashMap; use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; use rustc_macros::HashStable_Generic; use rustc_span::symbol::{kw, sym, Symbol}; use rustc_span::Span; use lazy_static::lazy_static; pub enum LangItemGroup { Op, } const NUM_GROUPS: usize = 1; macro_rules! expand_group { () => { None }; ($group:expr) => { Some($group) }; } // 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 { ( $( $variant:ident $($group:expr)?, $name:expr, $method:ident, $target:expr; )* ) => { enum_from_u32! { /// A representation of all the valid language items in Rust. #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] pub enum LangItem { $($variant,)* } } impl LangItem { /// Returns the `name` symbol in `#[lang = "$name"]`. /// For example, `LangItem::EqTraitLangItem`, /// that is `#[lang = "eq"]` would result in `sym::eq`. pub fn name(self) -> Symbol { match self { $( $variant => $name, )* } } pub fn group(self) -> Option { use LangItemGroup::*; match self { $( $variant => expand_group!($($group)*), )* } } } #[derive(HashStable_Generic)] pub struct LanguageItems { /// Mappings from lang items to their possibly found `DefId`s. /// The index corresponds to the order in `LangItem`. pub items: Vec>, /// Lang items that were not found during collection. pub missing: Vec, /// Mapping from `LangItemGroup` discriminants to all /// `DefId`s of lang items in that group. pub groups: [Vec; NUM_GROUPS], } impl LanguageItems { /// Construct an empty collection of lang items and no missing ones. pub fn new() -> Self { fn init_none(_: LangItem) -> Option { None } Self { items: vec![$(init_none($variant)),*], missing: Vec::new(), groups: [vec![]; NUM_GROUPS], } } /// Returns the mappings to the possibly found `DefId`s for each lang item. pub fn items(&self) -> &[Option] { &*self.items } /// Requires that a given `LangItem` was bound and returns the corresponding `DefId`. /// If it wasn't bound, e.g. due to a missing `#[lang = ""]`, /// returns an error message as a string. pub fn require(&self, it: LangItem) -> Result { self.items[it as usize].ok_or_else(|| format!("requires `{}` lang_item", it.name())) } pub fn group(&self, group: LangItemGroup) -> &[DefId] { self.groups[group as usize].as_ref() } $( /// Returns the corresponding `DefId` for the lang item if it /// exists. #[allow(dead_code)] pub fn $method(&self) -> Option { self.items[$variant as usize] } )* } lazy_static! { /// A mapping from the name of the lang item to its order and the form it must be of. pub static ref ITEM_REFS: FxHashMap = { let mut item_refs = FxHashMap::default(); $( item_refs.insert($name, ($variant as usize, $target)); )* item_refs }; } // End of the macro } } impl HashStable for LangItem { fn hash_stable(&self, _: &mut CTX, hasher: &mut StableHasher) { ::std::hash::Hash::hash(self, hasher); } } /// Extracts the first `lang = "$name"` out of a list of attributes. /// The attributes `#[panic_handler]` and `#[alloc_error_handler]` /// are also extracted out when found. pub fn extract(attrs: &[ast::Attribute]) -> Option<(Symbol, Span)> { attrs.iter().find_map(|attr| { Some(match attr { _ if attr.check_name(sym::lang) => (attr.value_str()?, attr.span), _ if attr.check_name(sym::panic_handler) => (sym::panic_impl, attr.span), _ if attr.check_name(sym::alloc_error_handler) => (sym::oom, attr.span), _ => return None, }) }) } language_item_table! { // Variant name, Name, Method name, Target; BoolImplItem, sym::bool, bool_impl, Target::Impl; CharImplItem, sym::char, char_impl, Target::Impl; StrImplItem, sym::str, str_impl, Target::Impl; SliceImplItem, sym::slice, slice_impl, Target::Impl; SliceU8ImplItem, sym::slice_u8, slice_u8_impl, Target::Impl; StrAllocImplItem, sym::str_alloc, str_alloc_impl, Target::Impl; SliceAllocImplItem, sym::slice_alloc, slice_alloc_impl, Target::Impl; SliceU8AllocImplItem, sym::slice_u8_alloc, slice_u8_alloc_impl, Target::Impl; ConstPtrImplItem, sym::const_ptr, const_ptr_impl, Target::Impl; MutPtrImplItem, sym::mut_ptr, mut_ptr_impl, Target::Impl; ConstSlicePtrImplItem, sym::const_slice_ptr, const_slice_ptr_impl, Target::Impl; MutSlicePtrImplItem, sym::mut_slice_ptr, mut_slice_ptr_impl, Target::Impl; I8ImplItem, sym::i8, i8_impl, Target::Impl; I16ImplItem, sym::i16, i16_impl, Target::Impl; I32ImplItem, sym::i32, i32_impl, Target::Impl; I64ImplItem, sym::i64, i64_impl, Target::Impl; I128ImplItem, sym::i128, i128_impl, Target::Impl; IsizeImplItem, sym::isize, isize_impl, Target::Impl; U8ImplItem, sym::u8, u8_impl, Target::Impl; U16ImplItem, sym::u16, u16_impl, Target::Impl; U32ImplItem, sym::u32, u32_impl, Target::Impl; U64ImplItem, sym::u64, u64_impl, Target::Impl; U128ImplItem, sym::u128, u128_impl, Target::Impl; UsizeImplItem, sym::usize, usize_impl, Target::Impl; F32ImplItem, sym::f32, f32_impl, Target::Impl; F64ImplItem, sym::f64, f64_impl, Target::Impl; F32RuntimeImplItem, sym::f32_runtime, f32_runtime_impl, Target::Impl; F64RuntimeImplItem, sym::f64_runtime, f64_runtime_impl, Target::Impl; SizedTraitLangItem, sym::sized, sized_trait, Target::Trait; UnsizeTraitLangItem, sym::unsize, unsize_trait, Target::Trait; // trait injected by #[derive(PartialEq)], (i.e. "Partial EQ"). StructuralPeqTraitLangItem, sym::structural_peq, structural_peq_trait, Target::Trait; // trait injected by #[derive(Eq)], (i.e. "Total EQ"; no, I will not apologize). StructuralTeqTraitLangItem, sym::structural_teq, structural_teq_trait, Target::Trait; CopyTraitLangItem, sym::copy, copy_trait, Target::Trait; CloneTraitLangItem, sym::clone, clone_trait, Target::Trait; SyncTraitLangItem, sym::sync, sync_trait, Target::Trait; DiscriminantKindTraitLangItem, sym::discriminant_kind, discriminant_kind_trait, Target::Trait; // The associated item of `trait DiscriminantKind`. DiscriminantTypeLangItem, sym::discriminant_type, discriminant_type, Target::AssocTy; FreezeTraitLangItem, sym::freeze, freeze_trait, Target::Trait; DropTraitLangItem, sym::drop, drop_trait, Target::Trait; CoerceUnsizedTraitLangItem, sym::coerce_unsized, coerce_unsized_trait, Target::Trait; DispatchFromDynTraitLangItem, sym::dispatch_from_dyn, dispatch_from_dyn_trait, Target::Trait; AddTraitLangItem(Op), sym::add, add_trait, Target::Trait; SubTraitLangItem(Op), sym::sub, sub_trait, Target::Trait; MulTraitLangItem(Op), sym::mul, mul_trait, Target::Trait; DivTraitLangItem(Op), sym::div, div_trait, Target::Trait; RemTraitLangItem(Op), sym::rem, rem_trait, Target::Trait; NegTraitLangItem(Op), sym::neg, neg_trait, Target::Trait; NotTraitLangItem(Op), sym::not, not_trait, Target::Trait; BitXorTraitLangItem(Op), sym::bitxor, bitxor_trait, Target::Trait; BitAndTraitLangItem(Op), sym::bitand, bitand_trait, Target::Trait; BitOrTraitLangItem(Op), sym::bitor, bitor_trait, Target::Trait; ShlTraitLangItem(Op), sym::shl, shl_trait, Target::Trait; ShrTraitLangItem(Op), sym::shr, shr_trait, Target::Trait; AddAssignTraitLangItem(Op), sym::add_assign, add_assign_trait, Target::Trait; SubAssignTraitLangItem(Op), sym::sub_assign, sub_assign_trait, Target::Trait; MulAssignTraitLangItem(Op), sym::mul_assign, mul_assign_trait, Target::Trait; DivAssignTraitLangItem(Op), sym::div_assign, div_assign_trait, Target::Trait; RemAssignTraitLangItem(Op), sym::rem_assign, rem_assign_trait, Target::Trait; BitXorAssignTraitLangItem(Op), sym::bitxor_assign, bitxor_assign_trait, Target::Trait; BitAndAssignTraitLangItem(Op), sym::bitand_assign, bitand_assign_trait, Target::Trait; BitOrAssignTraitLangItem(Op), sym::bitor_assign, bitor_assign_trait, Target::Trait; ShlAssignTraitLangItem(Op), sym::shl_assign, shl_assign_trait, Target::Trait; ShrAssignTraitLangItem(Op), sym::shr_assign, shr_assign_trait, Target::Trait; IndexTraitLangItem(Op), sym::index, index_trait, Target::Trait; IndexMutTraitLangItem(Op), sym::index_mut, index_mut_trait, Target::Trait; UnsafeCellTypeLangItem, sym::unsafe_cell, unsafe_cell_type, Target::Struct; VaListTypeLangItem, sym::va_list, va_list, Target::Struct; DerefTraitLangItem, sym::deref, deref_trait, Target::Trait; DerefMutTraitLangItem, sym::deref_mut, deref_mut_trait, Target::Trait; ReceiverTraitLangItem, sym::receiver, receiver_trait, Target::Trait; FnTraitLangItem, kw::Fn, fn_trait, Target::Trait; FnMutTraitLangItem, sym::fn_mut, fn_mut_trait, Target::Trait; FnOnceTraitLangItem, sym::fn_once, fn_once_trait, Target::Trait; FnOnceOutputLangItem, sym::fn_once_output, fn_once_output, Target::AssocTy; FutureTraitLangItem, sym::future_trait, future_trait, Target::Trait; GeneratorStateLangItem, sym::generator_state, gen_state, Target::Enum; GeneratorTraitLangItem, sym::generator, gen_trait, Target::Trait; UnpinTraitLangItem, sym::unpin, unpin_trait, Target::Trait; PinTypeLangItem, sym::pin, pin_type, Target::Struct; // Don't be fooled by the naming here: this lang item denotes `PartialEq`, not `Eq`. EqTraitLangItem, sym::eq, eq_trait, Target::Trait; PartialOrdTraitLangItem, sym::partial_ord, partial_ord_trait, Target::Trait; // 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. PanicFnLangItem, sym::panic, panic_fn, Target::Fn; PanicBoundsCheckFnLangItem, sym::panic_bounds_check, panic_bounds_check_fn, Target::Fn; PanicInfoLangItem, sym::panic_info, panic_info, Target::Struct; PanicLocationLangItem, sym::panic_location, panic_location, Target::Struct; PanicImplLangItem, sym::panic_impl, panic_impl, Target::Fn; // Libstd panic entry point. Necessary for const eval to be able to catch it BeginPanicFnLangItem, sym::begin_panic, begin_panic_fn, Target::Fn; ExchangeMallocFnLangItem, sym::exchange_malloc, exchange_malloc_fn, Target::Fn; BoxFreeFnLangItem, sym::box_free, box_free_fn, Target::Fn; DropInPlaceFnLangItem, sym::drop_in_place, drop_in_place_fn, Target::Fn; OomLangItem, sym::oom, oom, Target::Fn; AllocLayoutLangItem, sym::alloc_layout, alloc_layout, Target::Struct; StartFnLangItem, sym::start, start_fn, Target::Fn; CountCodeRegionFnLangItem, sym::count_code_region, count_code_region_fn, Target::Fn; EhPersonalityLangItem, sym::eh_personality, eh_personality, Target::Fn; EhCatchTypeinfoLangItem, sym::eh_catch_typeinfo, eh_catch_typeinfo, Target::Static; OwnedBoxLangItem, sym::owned_box, owned_box, Target::Struct; PhantomDataItem, sym::phantom_data, phantom_data, Target::Struct; ManuallyDropItem, sym::manually_drop, manually_drop, Target::Struct; MaybeUninitLangItem, sym::maybe_uninit, maybe_uninit, Target::Union; // Align offset for stride != 1; must not panic. AlignOffsetLangItem, sym::align_offset, align_offset_fn, Target::Fn; TerminationTraitLangItem, sym::termination, termination, Target::Trait; TryTraitLangItem, kw::Try, try_trait, Target::Trait; }