//! 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::{sym, Symbol}; use rustc_span::Span; use lazy_static::lazy_static; // 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, $name:expr, $method:ident, $target:path; )* ) => { 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` in `#[lang = "$name"]`. /// For example, `LangItem::EqTraitLangItem`, /// that is `#[lang = "eq"]` would result in `"eq"`. pub fn name(self) -> &'static str { match self { $( $variant => $name, )* } } } #[derive(HashStable_Generic)] pub struct LanguageItems { /// Mappings from lang items to their possibly found `DefId`s. /// The index corresponds to the order in `LangItem`. pub items: Vec>, /// Lang items that were not found during collection. pub missing: Vec, } impl LanguageItems { /// Construct an empty collection of lang items and no missing ones. pub fn new() -> Self { fn init_none(_: LangItem) -> Option { None } Self { items: vec![$(init_none($variant)),*], missing: Vec::new(), } } /// 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())) } $( /// Returns the corresponding `DefId` for the lang item #[doc = $name] /// 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<&'static str, (usize, Target)> = { 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, "bool", bool_impl, Target::Impl; CharImplItem, "char", char_impl, Target::Impl; StrImplItem, "str", str_impl, Target::Impl; SliceImplItem, "slice", slice_impl, Target::Impl; SliceU8ImplItem, "slice_u8", slice_u8_impl, Target::Impl; StrAllocImplItem, "str_alloc", str_alloc_impl, Target::Impl; SliceAllocImplItem, "slice_alloc", slice_alloc_impl, Target::Impl; SliceU8AllocImplItem, "slice_u8_alloc", slice_u8_alloc_impl, Target::Impl; ConstPtrImplItem, "const_ptr", const_ptr_impl, Target::Impl; MutPtrImplItem, "mut_ptr", mut_ptr_impl, Target::Impl; ConstSlicePtrImplItem, "const_slice_ptr", const_slice_ptr_impl, Target::Impl; MutSlicePtrImplItem, "mut_slice_ptr", mut_slice_ptr_impl, Target::Impl; I8ImplItem, "i8", i8_impl, Target::Impl; I16ImplItem, "i16", i16_impl, Target::Impl; I32ImplItem, "i32", i32_impl, Target::Impl; I64ImplItem, "i64", i64_impl, Target::Impl; I128ImplItem, "i128", i128_impl, Target::Impl; IsizeImplItem, "isize", isize_impl, Target::Impl; U8ImplItem, "u8", u8_impl, Target::Impl; U16ImplItem, "u16", u16_impl, Target::Impl; U32ImplItem, "u32", u32_impl, Target::Impl; U64ImplItem, "u64", u64_impl, Target::Impl; U128ImplItem, "u128", u128_impl, Target::Impl; UsizeImplItem, "usize", usize_impl, Target::Impl; F32ImplItem, "f32", f32_impl, Target::Impl; F64ImplItem, "f64", f64_impl, Target::Impl; F32RuntimeImplItem, "f32_runtime", f32_runtime_impl, Target::Impl; F64RuntimeImplItem, "f64_runtime", f64_runtime_impl, Target::Impl; SizedTraitLangItem, "sized", sized_trait, Target::Trait; UnsizeTraitLangItem, "unsize", unsize_trait, Target::Trait; // trait injected by #[derive(PartialEq)], (i.e. "Partial EQ"). StructuralPeqTraitLangItem, "structural_peq", structural_peq_trait, Target::Trait; // trait injected by #[derive(Eq)], (i.e. "Total EQ"; no, I will not apologize). StructuralTeqTraitLangItem, "structural_teq", structural_teq_trait, Target::Trait; CopyTraitLangItem, "copy", copy_trait, Target::Trait; CloneTraitLangItem, "clone", clone_trait, Target::Trait; SyncTraitLangItem, "sync", sync_trait, Target::Trait; DiscriminantKindTraitLangItem,"discriminant_kind", discriminant_kind_trait, Target::Trait; FreezeTraitLangItem, "freeze", freeze_trait, Target::Trait; DropTraitLangItem, "drop", drop_trait, Target::Trait; CoerceUnsizedTraitLangItem, "coerce_unsized", coerce_unsized_trait, Target::Trait; DispatchFromDynTraitLangItem,"dispatch_from_dyn", dispatch_from_dyn_trait, Target::Trait; AddTraitLangItem, "add", add_trait, Target::Trait; SubTraitLangItem, "sub", sub_trait, Target::Trait; MulTraitLangItem, "mul", mul_trait, Target::Trait; DivTraitLangItem, "div", div_trait, Target::Trait; RemTraitLangItem, "rem", rem_trait, Target::Trait; NegTraitLangItem, "neg", neg_trait, Target::Trait; NotTraitLangItem, "not", not_trait, Target::Trait; BitXorTraitLangItem, "bitxor", bitxor_trait, Target::Trait; BitAndTraitLangItem, "bitand", bitand_trait, Target::Trait; BitOrTraitLangItem, "bitor", bitor_trait, Target::Trait; ShlTraitLangItem, "shl", shl_trait, Target::Trait; ShrTraitLangItem, "shr", shr_trait, Target::Trait; AddAssignTraitLangItem, "add_assign", add_assign_trait, Target::Trait; SubAssignTraitLangItem, "sub_assign", sub_assign_trait, Target::Trait; MulAssignTraitLangItem, "mul_assign", mul_assign_trait, Target::Trait; DivAssignTraitLangItem, "div_assign", div_assign_trait, Target::Trait; RemAssignTraitLangItem, "rem_assign", rem_assign_trait, Target::Trait; BitXorAssignTraitLangItem, "bitxor_assign", bitxor_assign_trait, Target::Trait; BitAndAssignTraitLangItem, "bitand_assign", bitand_assign_trait, Target::Trait; BitOrAssignTraitLangItem, "bitor_assign", bitor_assign_trait, Target::Trait; ShlAssignTraitLangItem, "shl_assign", shl_assign_trait, Target::Trait; ShrAssignTraitLangItem, "shr_assign", shr_assign_trait, Target::Trait; IndexTraitLangItem, "index", index_trait, Target::Trait; IndexMutTraitLangItem, "index_mut", index_mut_trait, Target::Trait; UnsafeCellTypeLangItem, "unsafe_cell", unsafe_cell_type, Target::Struct; VaListTypeLangItem, "va_list", va_list, Target::Struct; DerefTraitLangItem, "deref", deref_trait, Target::Trait; DerefMutTraitLangItem, "deref_mut", deref_mut_trait, Target::Trait; ReceiverTraitLangItem, "receiver", receiver_trait, Target::Trait; FnTraitLangItem, "fn", fn_trait, Target::Trait; FnMutTraitLangItem, "fn_mut", fn_mut_trait, Target::Trait; FnOnceTraitLangItem, "fn_once", fn_once_trait, Target::Trait; FutureTraitLangItem, "future_trait", future_trait, Target::Trait; GeneratorStateLangItem, "generator_state", gen_state, Target::Enum; GeneratorTraitLangItem, "generator", gen_trait, Target::Trait; UnpinTraitLangItem, "unpin", unpin_trait, Target::Trait; PinTypeLangItem, "pin", pin_type, Target::Struct; // Don't be fooled by the naming here: this lang item denotes `PartialEq`, not `Eq`. EqTraitLangItem, "eq", eq_trait, Target::Trait; PartialOrdTraitLangItem, "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, "panic", panic_fn, Target::Fn; PanicBoundsCheckFnLangItem, "panic_bounds_check", panic_bounds_check_fn, Target::Fn; PanicInfoLangItem, "panic_info", panic_info, Target::Struct; PanicLocationLangItem, "panic_location", panic_location, Target::Struct; PanicImplLangItem, "panic_impl", panic_impl, Target::Fn; // Libstd panic entry point. Necessary for const eval to be able to catch it BeginPanicFnLangItem, "begin_panic", begin_panic_fn, Target::Fn; ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn, Target::Fn; BoxFreeFnLangItem, "box_free", box_free_fn, Target::Fn; DropInPlaceFnLangItem, "drop_in_place", drop_in_place_fn, Target::Fn; OomLangItem, "oom", oom, Target::Fn; AllocLayoutLangItem, "alloc_layout", alloc_layout, Target::Struct; StartFnLangItem, "start", start_fn, Target::Fn; CountCodeRegionFnLangItem, "count_code_region", count_code_region_fn, Target::Fn; EhPersonalityLangItem, "eh_personality", eh_personality, Target::Fn; EhCatchTypeinfoLangItem, "eh_catch_typeinfo", eh_catch_typeinfo, Target::Static; OwnedBoxLangItem, "owned_box", owned_box, Target::Struct; PhantomDataItem, "phantom_data", phantom_data, Target::Struct; ManuallyDropItem, "manually_drop", manually_drop, Target::Struct; MaybeUninitLangItem, "maybe_uninit", maybe_uninit, Target::Union; // Align offset for stride != 1; must not panic. AlignOffsetLangItem, "align_offset", align_offset_fn, Target::Fn; TerminationTraitLangItem, "termination", termination, Target::Trait; TryTraitLangItem, "try", try_trait, Target::Trait; }