//! 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::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, Encodable, Decodable)] 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 { $( LangItem::$variant => $name, )* } } pub fn group(self) -> Option { use LangItemGroup::*; match self { $( LangItem::$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![$(init_none(LangItem::$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 $method(&self) -> Option { self.items[LangItem::$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, (LangItem::$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. /// /// About the `check_name` argument: passing in a `Session` would be simpler, /// because then we could call `Session::check_name` directly. But we want to /// avoid the need for `librustc_hir` to depend on `librustc_session`, so we /// use a closure instead. pub fn extract<'a, F>(check_name: F, attrs: &'a [ast::Attribute]) -> Option<(Symbol, Span)> where F: Fn(&'a ast::Attribute, Symbol) -> bool, { attrs.iter().find_map(|attr| { Some(match attr { _ if check_name(attr, sym::lang) => (attr.value_str()?, attr.span), _ if check_name(attr, sym::panic_handler) => (sym::panic_impl, attr.span), _ if check_name(attr, sym::alloc_error_handler) => (sym::oom, attr.span), _ => return None, }) }) } language_item_table! { // Variant name, Name, Method name, Target; Bool, sym::bool, bool_impl, Target::Impl; Char, sym::char, char_impl, Target::Impl; Str, sym::str, str_impl, Target::Impl; Array, sym::array, array_impl, Target::Impl; Slice, sym::slice, slice_impl, Target::Impl; SliceU8, sym::slice_u8, slice_u8_impl, Target::Impl; StrAlloc, sym::str_alloc, str_alloc_impl, Target::Impl; SliceAlloc, sym::slice_alloc, slice_alloc_impl, Target::Impl; SliceU8Alloc, sym::slice_u8_alloc, slice_u8_alloc_impl, Target::Impl; ConstPtr, sym::const_ptr, const_ptr_impl, Target::Impl; MutPtr, sym::mut_ptr, mut_ptr_impl, Target::Impl; ConstSlicePtr, sym::const_slice_ptr, const_slice_ptr_impl, Target::Impl; MutSlicePtr, sym::mut_slice_ptr, mut_slice_ptr_impl, Target::Impl; I8, sym::i8, i8_impl, Target::Impl; I16, sym::i16, i16_impl, Target::Impl; I32, sym::i32, i32_impl, Target::Impl; I64, sym::i64, i64_impl, Target::Impl; I128, sym::i128, i128_impl, Target::Impl; Isize, sym::isize, isize_impl, Target::Impl; U8, sym::u8, u8_impl, Target::Impl; U16, sym::u16, u16_impl, Target::Impl; U32, sym::u32, u32_impl, Target::Impl; U64, sym::u64, u64_impl, Target::Impl; U128, sym::u128, u128_impl, Target::Impl; Usize, sym::usize, usize_impl, Target::Impl; F32, sym::f32, f32_impl, Target::Impl; F64, sym::f64, f64_impl, Target::Impl; F32Runtime, sym::f32_runtime, f32_runtime_impl, Target::Impl; F64Runtime, sym::f64_runtime, f64_runtime_impl, Target::Impl; Sized, sym::sized, sized_trait, Target::Trait; Unsize, sym::unsize, unsize_trait, Target::Trait; // Trait injected by #[derive(PartialEq)], (i.e. "Partial EQ"). StructuralPeq, sym::structural_peq, structural_peq_trait, Target::Trait; // Trait injected by #[derive(Eq)], (i.e. "Total EQ"; no, I will not apologize). StructuralTeq, sym::structural_teq, structural_teq_trait, Target::Trait; Copy, sym::copy, copy_trait, Target::Trait; Clone, sym::clone, clone_trait, Target::Trait; Sync, sym::sync, sync_trait, Target::Trait; DiscriminantKind, sym::discriminant_kind, discriminant_kind_trait, Target::Trait; // The associated item of `trait DiscriminantKind`. Discriminant, sym::discriminant_type, discriminant_type, Target::AssocTy; Freeze, sym::freeze, freeze_trait, Target::Trait; Drop, sym::drop, drop_trait, Target::Trait; CoerceUnsized, sym::coerce_unsized, coerce_unsized_trait, Target::Trait; DispatchFromDyn, sym::dispatch_from_dyn, dispatch_from_dyn_trait, Target::Trait; Add(Op), sym::add, add_trait, Target::Trait; Sub(Op), sym::sub, sub_trait, Target::Trait; Mul(Op), sym::mul, mul_trait, Target::Trait; Div(Op), sym::div, div_trait, Target::Trait; Rem(Op), sym::rem, rem_trait, Target::Trait; Neg(Op), sym::neg, neg_trait, Target::Trait; Not(Op), sym::not, not_trait, Target::Trait; BitXor(Op), sym::bitxor, bitxor_trait, Target::Trait; BitAnd(Op), sym::bitand, bitand_trait, Target::Trait; BitOr(Op), sym::bitor, bitor_trait, Target::Trait; Shl(Op), sym::shl, shl_trait, Target::Trait; Shr(Op), sym::shr, shr_trait, Target::Trait; AddAssign(Op), sym::add_assign, add_assign_trait, Target::Trait; SubAssign(Op), sym::sub_assign, sub_assign_trait, Target::Trait; MulAssign(Op), sym::mul_assign, mul_assign_trait, Target::Trait; DivAssign(Op), sym::div_assign, div_assign_trait, Target::Trait; RemAssign(Op), sym::rem_assign, rem_assign_trait, Target::Trait; BitXorAssign(Op), sym::bitxor_assign, bitxor_assign_trait, Target::Trait; BitAndAssign(Op), sym::bitand_assign, bitand_assign_trait, Target::Trait; BitOrAssign(Op), sym::bitor_assign, bitor_assign_trait, Target::Trait; ShlAssign(Op), sym::shl_assign, shl_assign_trait, Target::Trait; ShrAssign(Op), sym::shr_assign, shr_assign_trait, Target::Trait; Index(Op), sym::index, index_trait, Target::Trait; IndexMut(Op), sym::index_mut, index_mut_trait, Target::Trait; UnsafeCell, sym::unsafe_cell, unsafe_cell_type, Target::Struct; VaList, sym::va_list, va_list, Target::Struct; Deref, sym::deref, deref_trait, Target::Trait; DerefMut, sym::deref_mut, deref_mut_trait, Target::Trait; Receiver, sym::receiver, receiver_trait, Target::Trait; Fn, kw::Fn, fn_trait, Target::Trait; FnMut, sym::fn_mut, fn_mut_trait, Target::Trait; FnOnce, sym::fn_once, fn_once_trait, Target::Trait; FnOnceOutput, sym::fn_once_output, fn_once_output, Target::AssocTy; Future, sym::future_trait, future_trait, Target::Trait; GeneratorState, sym::generator_state, gen_state, Target::Enum; Generator, sym::generator, gen_trait, Target::Trait; Unpin, sym::unpin, unpin_trait, Target::Trait; Pin, sym::pin, pin_type, Target::Struct; PartialEq, sym::eq, eq_trait, Target::Trait; PartialOrd, 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. Panic, sym::panic, panic_fn, Target::Fn; PanicBoundsCheck, sym::panic_bounds_check, panic_bounds_check_fn, Target::Fn; PanicInfo, sym::panic_info, panic_info, Target::Struct; PanicLocation, sym::panic_location, panic_location, Target::Struct; PanicImpl, sym::panic_impl, panic_impl, Target::Fn; // libstd panic entry point. Necessary for const eval to be able to catch it BeginPanic, sym::begin_panic, begin_panic_fn, Target::Fn; ExchangeMalloc, sym::exchange_malloc, exchange_malloc_fn, Target::Fn; BoxFree, sym::box_free, box_free_fn, Target::Fn; DropInPlace, sym::drop_in_place, drop_in_place_fn, Target::Fn; Oom, sym::oom, oom, Target::Fn; AllocLayout, sym::alloc_layout, alloc_layout, Target::Struct; Start, sym::start, start_fn, Target::Fn; EhPersonality, sym::eh_personality, eh_personality, Target::Fn; EhCatchTypeinfo, sym::eh_catch_typeinfo, eh_catch_typeinfo, Target::Static; OwnedBox, sym::owned_box, owned_box, Target::Struct; PhantomData, sym::phantom_data, phantom_data, Target::Struct; ManuallyDrop, sym::manually_drop, manually_drop, Target::Struct; MaybeUninit, sym::maybe_uninit, maybe_uninit, Target::Union; // Align offset for stride != 1; must not panic. AlignOffset, sym::align_offset, align_offset_fn, Target::Fn; Termination, sym::termination, termination, Target::Trait; Try, kw::Try, try_trait, Target::Trait; // Language items from AST lowering TryFromError, sym::from_error, from_error_fn, Target::Method(MethodKind::Trait { body: false }); TryFromOk, sym::from_ok, from_ok_fn, Target::Method(MethodKind::Trait { body: false }); TryIntoResult, sym::into_result, into_result_fn, Target::Method(MethodKind::Trait { body: false }); PollReady, sym::Ready, poll_ready_variant, Target::Variant; PollPending, sym::Pending, poll_pending_variant, Target::Variant; FromGenerator, sym::from_generator, from_generator_fn, Target::Fn; GetContext, sym::get_context, get_context_fn, Target::Fn; FuturePoll, sym::poll, future_poll_fn, Target::Method(MethodKind::Trait { body: false }); FromFrom, sym::from, from_fn, Target::Method(MethodKind::Trait { body: false }); OptionSome, sym::Some, option_some_variant, Target::Variant; OptionNone, sym::None, option_none_variant, Target::Variant; ResultOk, sym::Ok, result_ok_variant, Target::Variant; ResultErr, sym::Err, result_err_variant, Target::Variant; IntoIterIntoIter, sym::into_iter, into_iter_fn, Target::Method(MethodKind::Trait { body: false }); IteratorNext, sym::next, next_fn, Target::Method(MethodKind::Trait { body: false}); PinNewUnchecked, sym::new_unchecked, new_unchecked_fn, Target::Method(MethodKind::Inherent); RangeFrom, sym::RangeFrom, range_from_struct, Target::Struct; RangeFull, sym::RangeFull, range_full_struct, Target::Struct; RangeInclusiveStruct, sym::RangeInclusive, range_inclusive_struct, Target::Struct; RangeInclusiveNew, sym::range_inclusive_new, range_inclusive_new_method, Target::Method(MethodKind::Inherent); Range, sym::Range, range_struct, Target::Struct; RangeToInclusive, sym::RangeToInclusive, range_to_inclusive_struct, Target::Struct; RangeTo, sym::RangeTo, range_to_struct, Target::Struct; }