| //! 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 std::lazy::SyncLazy; |
| |
| 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 { |
| ( |
| $( $(#[$attr:meta])* $variant:ident $($group:expr)?, $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, )* |
| } |
| } |
| |
| /// The [group](LangItemGroup) that this lang item belongs to, |
| /// or `None` if it doesn't belong to a group. |
| pub fn group(self) -> Option<LangItemGroup> { |
| use LangItemGroup::*; |
| match self { |
| $( LangItem::$variant => expand_group!($($group)*), )* |
| } |
| } |
| |
| pub fn required_generics(&self) -> GenericRequirement { |
| match self { |
| $( LangItem::$variant => $generics, )* |
| } |
| } |
| } |
| |
| /// All of the language items, defined or not. |
| /// Defined lang items can come from the current crate or its dependencies. |
| #[derive(HashStable_Generic, Debug)] |
| pub struct LanguageItems { |
| /// Mappings from lang items to their possibly found [`DefId`]s. |
| /// The index corresponds to the order in [`LangItem`]. |
| pub items: Vec<Option<DefId>>, |
| /// Lang items that were not found during collection. |
| pub missing: Vec<LangItem>, |
| /// Mapping from [`LangItemGroup`] discriminants to all |
| /// [`DefId`]s of lang items in that group. |
| pub groups: [Vec<DefId>; NUM_GROUPS], |
| } |
| |
| impl LanguageItems { |
| /// Construct an empty collection of lang items and no missing ones. |
| pub fn new() -> Self { |
| fn init_none(_: LangItem) -> Option<DefId> { None } |
| |
| Self { |
| items: vec![$(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<DefId>] { |
| &*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 = "<it.name()>"]`, |
| /// returns an error message as a string. |
| pub fn require(&self, it: LangItem) -> Result<DefId, String> { |
| self.items[it as usize].ok_or_else(|| format!("requires `{}` lang_item", it.name())) |
| } |
| |
| /// Returns the [`DefId`]s of all lang items in a group. |
| pub fn group(&self, group: LangItemGroup) -> &[DefId] { |
| self.groups[group as usize].as_ref() |
| } |
| |
| $( |
| #[doc = concat!("Returns the [`DefId`] of the `", stringify!($name), "` lang item if it is defined.")] |
| pub fn $method(&self) -> Option<DefId> { |
| self.items[LangItem::$variant as usize] |
| } |
| )* |
| } |
| |
| /// A mapping from the name of the lang item to its order and the form it must be of. |
| pub static ITEM_REFS: SyncLazy<FxHashMap<Symbol, (usize, Target)>> = SyncLazy::new(|| { |
| let mut item_refs = FxHashMap::default(); |
| $( item_refs.insert($module::$name, (LangItem::$variant as usize, $target)); )* |
| item_refs |
| }); |
| |
| // End of the macro |
| } |
| } |
| |
| impl<CTX> HashStable<CTX> for LangItem { |
| fn hash_stable(&self, _: &mut CTX, hasher: &mut StableHasher) { |
| ::std::hash::Hash::hash(self, hasher); |
| } |
| } |
| |
| /// Extracts the first `lang = "$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 `rustc_hir` to depend on `rustc_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 Generic requirements; |
| Bool, sym::bool, bool_impl, Target::Impl, GenericRequirement::None; |
| Char, sym::char, char_impl, Target::Impl, GenericRequirement::None; |
| Str, sym::str, str_impl, Target::Impl, GenericRequirement::None; |
| Array, sym::array, array_impl, Target::Impl, GenericRequirement::None; |
| Slice, sym::slice, slice_impl, Target::Impl, GenericRequirement::None; |
| SliceU8, sym::slice_u8, slice_u8_impl, Target::Impl, GenericRequirement::None; |
| StrAlloc, sym::str_alloc, str_alloc_impl, Target::Impl, GenericRequirement::None; |
| SliceAlloc, sym::slice_alloc, slice_alloc_impl, Target::Impl, GenericRequirement::None; |
| SliceU8Alloc, sym::slice_u8_alloc, slice_u8_alloc_impl, Target::Impl, GenericRequirement::None; |
| ConstPtr, sym::const_ptr, const_ptr_impl, Target::Impl, GenericRequirement::None; |
| MutPtr, sym::mut_ptr, mut_ptr_impl, Target::Impl, GenericRequirement::None; |
| ConstSlicePtr, sym::const_slice_ptr, const_slice_ptr_impl, Target::Impl, GenericRequirement::None; |
| MutSlicePtr, sym::mut_slice_ptr, mut_slice_ptr_impl, Target::Impl, GenericRequirement::None; |
| I8, sym::i8, i8_impl, Target::Impl, GenericRequirement::None; |
| I16, sym::i16, i16_impl, Target::Impl, GenericRequirement::None; |
| I32, sym::i32, i32_impl, Target::Impl, GenericRequirement::None; |
| I64, sym::i64, i64_impl, Target::Impl, GenericRequirement::None; |
| I128, sym::i128, i128_impl, Target::Impl, GenericRequirement::None; |
| Isize, sym::isize, isize_impl, Target::Impl, GenericRequirement::None; |
| U8, sym::u8, u8_impl, Target::Impl, GenericRequirement::None; |
| U16, sym::u16, u16_impl, Target::Impl, GenericRequirement::None; |
| U32, sym::u32, u32_impl, Target::Impl, GenericRequirement::None; |
| U64, sym::u64, u64_impl, Target::Impl, GenericRequirement::None; |
| U128, sym::u128, u128_impl, Target::Impl, GenericRequirement::None; |
| Usize, sym::usize, usize_impl, Target::Impl, GenericRequirement::None; |
| F32, sym::f32, f32_impl, Target::Impl, GenericRequirement::None; |
| F64, sym::f64, f64_impl, Target::Impl, GenericRequirement::None; |
| F32Runtime, sym::f32_runtime, f32_runtime_impl, Target::Impl, GenericRequirement::None; |
| F64Runtime, sym::f64_runtime, f64_runtime_impl, Target::Impl, GenericRequirement::None; |
| |
| 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); |
| |
| Drop, sym::drop, drop_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); |
| |
| Add(Op), sym::add, add_trait, Target::Trait, GenericRequirement::Exact(1); |
| Sub(Op), sym::sub, sub_trait, Target::Trait, GenericRequirement::Exact(1); |
| Mul(Op), sym::mul, mul_trait, Target::Trait, GenericRequirement::Exact(1); |
| Div(Op), sym::div, div_trait, Target::Trait, GenericRequirement::Exact(1); |
| Rem(Op), sym::rem, rem_trait, Target::Trait, GenericRequirement::Exact(1); |
| Neg(Op), sym::neg, neg_trait, Target::Trait, GenericRequirement::Exact(0); |
| Not(Op), sym::not, not_trait, Target::Trait, GenericRequirement::Exact(0); |
| BitXor(Op), sym::bitxor, bitxor_trait, Target::Trait, GenericRequirement::Exact(1); |
| BitAnd(Op), sym::bitand, bitand_trait, Target::Trait, GenericRequirement::Exact(1); |
| BitOr(Op), sym::bitor, bitor_trait, Target::Trait, GenericRequirement::Exact(1); |
| Shl(Op), sym::shl, shl_trait, Target::Trait, GenericRequirement::Exact(1); |
| Shr(Op), sym::shr, shr_trait, Target::Trait, GenericRequirement::Exact(1); |
| AddAssign(Op), sym::add_assign, add_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| SubAssign(Op), sym::sub_assign, sub_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| MulAssign(Op), sym::mul_assign, mul_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| DivAssign(Op), sym::div_assign, div_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| RemAssign(Op), sym::rem_assign, rem_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| BitXorAssign(Op), sym::bitxor_assign, bitxor_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| BitAndAssign(Op), sym::bitand_assign, bitand_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| BitOrAssign(Op), sym::bitor_assign, bitor_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| ShlAssign(Op), sym::shl_assign, shl_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| ShrAssign(Op), sym::shr_assign, shr_assign_trait, Target::Trait, GenericRequirement::Exact(1); |
| Index(Op), sym::index, index_trait, Target::Trait, GenericRequirement::Exact(1); |
| IndexMut(Op), 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); |
| GeneratorReturn, sym::generator_return, generator_return, Target::AssocTy, GenericRequirement::None; |
| 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); |
| |
| // 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); |
| PanicFmt, sym::panic_fmt, panic_fmt, Target::Fn, GenericRequirement::None; |
| PanicDisplay, sym::panic_display, panic_display, Target::Fn, GenericRequirement::None; |
| PanicStr, sym::panic_str, panic_str, 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); |
| 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; |
| /// 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; |
| |
| ExchangeMalloc, sym::exchange_malloc, exchange_malloc_fn, Target::Fn, GenericRequirement::None; |
| BoxFree, sym::box_free, box_free_fn, Target::Fn, GenericRequirement::Minimum(1); |
| DropInPlace, sym::drop_in_place, drop_in_place_fn, Target::Fn, GenericRequirement::Minimum(1); |
| Oom, sym::oom, oom, Target::Fn, GenericRequirement::None; |
| AllocLayout, sym::alloc_layout, alloc_layout, Target::Struct, GenericRequirement::None; |
| ConstEvalSelect, sym::const_eval_select, const_eval_select, Target::Fn, GenericRequirement::Exact(4); |
| ConstConstEvalSelect, sym::const_eval_select_ct,const_eval_select_ct, Target::Fn, GenericRequirement::Exact(4); |
| |
| 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); |
| |
| 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; |
| |
| 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; |
| |
| PollReady, sym::Ready, poll_ready_variant, Target::Variant, GenericRequirement::None; |
| PollPending, sym::Pending, poll_pending_variant, Target::Variant, GenericRequirement::None; |
| |
| FromGenerator, sym::from_generator, from_generator_fn, Target::Fn, GenericRequirement::None; |
| GetContext, sym::get_context, get_context_fn, Target::Fn, GenericRequirement::None; |
| |
| FuturePoll, sym::poll, future_poll_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None; |
| |
| FromFrom, sym::from, from_fn, Target::Method(MethodKind::Trait { body: false }), 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; |
| |
| 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; |
| } |
| |
| pub enum GenericRequirement { |
| None, |
| Minimum(usize), |
| Exact(usize), |
| } |
