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Diffstat (limited to 'compiler/rustc_hir/src/lang_items.rs')
| -rw-r--r-- | compiler/rustc_hir/src/lang_items.rs | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs new file mode 100644 index 000000000..c337be12a --- /dev/null +++ b/compiler/rustc_hir/src/lang_items.rs @@ -0,0 +1,339 @@ +//! 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::FxIndexMap; +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::sync::LazyLock; + +pub enum LangItemGroup { + Op, + Fn, +} + +const NUM_GROUPS: usize = 2; + +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 => $generics, )* + } + } + } + + /// All of the language items, defined or not. + /// Defined lang items can come from the current crate or its dependencies. + #[derive(HashStable_Generic, Debug)] + pub struct LanguageItems { + /// Mappings from lang items to their possibly found [`DefId`]s. + /// The index corresponds to the order in [`LangItem`]. + pub items: Vec<Option<DefId>>, + /// Lang items that were not found during collection. + pub missing: Vec<LangItem>, + /// Mapping from [`LangItemGroup`] discriminants to all + /// [`DefId`]s of lang items in that group. + pub groups: [Vec<DefId>; NUM_GROUPS], + } + + impl LanguageItems { + /// Construct an empty collection of lang items and no missing ones. + pub fn new() -> Self { + fn init_none(_: LangItem) -> Option<DefId> { None } + const EMPTY: Vec<DefId> = Vec::new(); + + Self { + items: vec![$(init_none(LangItem::$variant)),*], + missing: Vec::new(), + groups: [EMPTY; 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: LazyLock<FxIndexMap<Symbol, (usize, Target)>> = LazyLock::new(|| { + let mut item_refs = FxIndexMap::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. +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), + _ if attr.has_name(sym::alloc_error_handler) => (sym::oom, attr.span), + _ => return None, + }) + }) +} + +language_item_table! { +// Variant name, Name, 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); + + 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 + TransmuteTrait, sym::transmute_trait, transmute_trait, Target::Trait, GenericRequirement::Exact(6); + + 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(Fn), kw::Fn, fn_trait, Target::Trait, GenericRequirement::Exact(1); + FnMut(Fn), sym::fn_mut, fn_mut_trait, Target::Trait, GenericRequirement::Exact(1); + FnOnce(Fn), 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(Op), sym::eq, eq_trait, Target::Trait, GenericRequirement::Exact(1); + PartialOrd(Op), 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; + 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; + PanicNoUnwind, sym::panic_no_unwind, panic_no_unwind, 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; + + 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; + TryTraitFromYeet, sym::from_yeet, from_yeet_fn, Target::Fn, 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; + + 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; +} + +pub enum GenericRequirement { + None, + Minimum(usize), + Exact(usize), +} |