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//! 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::stable_hasher::{HashStable, StableHasher};
use rustc_macros::HashStable_Generic;
use rustc_span::symbol::{kw, sym, Symbol};
use rustc_span::Span;
/// 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`].
items: [Option<DefId>; std::mem::variant_count::<LangItem>()],
/// Lang items that were not found during collection.
pub missing: Vec<LangItem>,
}
impl LanguageItems {
/// Construct an empty collection of lang items and no missing ones.
pub fn new() -> Self {
Self { items: [None; std::mem::variant_count::<LangItem>()], missing: Vec::new() }
}
pub fn get(&self, item: LangItem) -> Option<DefId> {
self.items[item as usize]
}
pub fn set(&mut self, item: LangItem, def_id: DefId) {
self.items[item as usize] = Some(def_id);
}
pub fn iter(&self) -> impl Iterator<Item = (LangItem, DefId)> + '_ {
self.items
.iter()
.enumerate()
.filter_map(|(i, id)| id.map(|id| (LangItem::from_u32(i as u32).unwrap(), id)))
}
}
// 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, $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, )*
}
}
/// Opposite of [`LangItem::name`]
pub fn from_name(name: Symbol) -> Option<Self> {
match name {
$( $module::$name => Some(LangItem::$variant), )*
_ => None,
}
}
/// Returns the name of the `LangItem` enum variant.
// This method is used by Clippy for internal lints.
pub fn variant_name(self) -> &'static str {
match self {
$( LangItem::$variant => stringify!($variant), )*
}
}
pub fn target(self) -> Target {
match self {
$( LangItem::$variant => $target, )*
}
}
pub fn required_generics(&self) -> GenericRequirement {
match self {
$( LangItem::$variant => $generics, )*
}
}
}
impl LanguageItems {
$(
#[doc = concat!("Returns the [`DefId`] of the `", stringify!($name), "` lang item if it is defined.")]
pub fn $method(&self) -> Option<DefId> {
self.items[LangItem::$variant as usize]
}
)*
}
}
}
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 `#[panic_handler]` attribute is 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),
_ => return None,
})
})
}
language_item_table! {
// Variant name, Name, Getter 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);
FnPtrTrait, sym::fn_ptr_trait, fn_ptr_trait, Target::Trait, GenericRequirement::Exact(0);
FnPtrAddr, sym::fn_ptr_addr, fn_ptr_addr, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
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
TransmuteOpts, sym::transmute_opts, transmute_opts, Target::Struct, GenericRequirement::Exact(0);
TransmuteTrait, sym::transmute_trait, transmute_trait, Target::Trait, GenericRequirement::Exact(3);
Add, sym::add, add_trait, Target::Trait, GenericRequirement::Exact(1);
Sub, sym::sub, sub_trait, Target::Trait, GenericRequirement::Exact(1);
Mul, sym::mul, mul_trait, Target::Trait, GenericRequirement::Exact(1);
Div, sym::div, div_trait, Target::Trait, GenericRequirement::Exact(1);
Rem, sym::rem, rem_trait, Target::Trait, GenericRequirement::Exact(1);
Neg, sym::neg, neg_trait, Target::Trait, GenericRequirement::Exact(0);
Not, sym::not, not_trait, Target::Trait, GenericRequirement::Exact(0);
BitXor, sym::bitxor, bitxor_trait, Target::Trait, GenericRequirement::Exact(1);
BitAnd, sym::bitand, bitand_trait, Target::Trait, GenericRequirement::Exact(1);
BitOr, sym::bitor, bitor_trait, Target::Trait, GenericRequirement::Exact(1);
Shl, sym::shl, shl_trait, Target::Trait, GenericRequirement::Exact(1);
Shr, sym::shr, shr_trait, Target::Trait, GenericRequirement::Exact(1);
AddAssign, sym::add_assign, add_assign_trait, Target::Trait, GenericRequirement::Exact(1);
SubAssign, sym::sub_assign, sub_assign_trait, Target::Trait, GenericRequirement::Exact(1);
MulAssign, sym::mul_assign, mul_assign_trait, Target::Trait, GenericRequirement::Exact(1);
DivAssign, sym::div_assign, div_assign_trait, Target::Trait, GenericRequirement::Exact(1);
RemAssign, sym::rem_assign, rem_assign_trait, Target::Trait, GenericRequirement::Exact(1);
BitXorAssign, sym::bitxor_assign, bitxor_assign_trait, Target::Trait, GenericRequirement::Exact(1);
BitAndAssign, sym::bitand_assign, bitand_assign_trait, Target::Trait, GenericRequirement::Exact(1);
BitOrAssign, sym::bitor_assign, bitor_assign_trait, Target::Trait, GenericRequirement::Exact(1);
ShlAssign, sym::shl_assign, shl_assign_trait, Target::Trait, GenericRequirement::Exact(1);
ShrAssign, sym::shr_assign, shr_assign_trait, Target::Trait, GenericRequirement::Exact(1);
Index, sym::index, index_trait, Target::Trait, GenericRequirement::Exact(1);
IndexMut, 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);
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);
CVoid, sym::c_void, c_void, Target::Enum, GenericRequirement::None;
// 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);
PanicNounwind, sym::panic_nounwind, panic_nounwind, 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);
PanicMisalignedPointerDereference, sym::panic_misaligned_pointer_dereference, panic_misaligned_pointer_dereference_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;
PanicCannotUnwind, sym::panic_cannot_unwind, panic_cannot_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;
// Lang items needed for `format_args!()`.
FormatAlignment, sym::format_alignment, format_alignment, Target::Enum, GenericRequirement::None;
FormatArgument, sym::format_argument, format_argument, Target::Struct, GenericRequirement::None;
FormatArguments, sym::format_arguments, format_arguments, Target::Struct, GenericRequirement::None;
FormatCount, sym::format_count, format_count, Target::Enum, GenericRequirement::None;
FormatPlaceholder, sym::format_placeholder, format_placeholder, Target::Struct, GenericRequirement::None;
FormatUnsafeArg, sym::format_unsafe_arg, format_unsafe_arg, Target::Struct, GenericRequirement::None;
ExchangeMalloc, sym::exchange_malloc, exchange_malloc_fn, Target::Fn, GenericRequirement::None;
DropInPlace, sym::drop_in_place, drop_in_place_fn, Target::Fn, GenericRequirement::Minimum(1);
AllocLayout, sym::alloc_layout, alloc_layout, Target::Struct, GenericRequirement::None;
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);
// Experimental language item for Miri
PtrUnique, sym::ptr_unique, ptr_unique, Target::Struct, GenericRequirement::Exact(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;
Tuple, sym::tuple_trait, tuple_trait, Target::Trait, GenericRequirement::Exact(0);
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;
PointerLike, sym::pointer_like, pointer_like, Target::Trait, GenericRequirement::Exact(0);
ConstParamTy, sym::const_param_ty, const_param_ty_trait, Target::Trait, GenericRequirement::Exact(0);
Poll, sym::Poll, poll, Target::Enum, GenericRequirement::None;
PollReady, sym::Ready, poll_ready_variant, Target::Variant, GenericRequirement::None;
PollPending, sym::Pending, poll_pending_variant, Target::Variant, GenericRequirement::None;
// FIXME(swatinem): the following lang items are used for async lowering and
// should become obsolete eventually.
ResumeTy, sym::ResumeTy, resume_ty, Target::Struct, GenericRequirement::None;
GetContext, sym::get_context, get_context_fn, Target::Fn, GenericRequirement::None;
Context, sym::Context, context, Target::Struct, GenericRequirement::None;
FuturePoll, sym::poll, future_poll_fn, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
Option, sym::Option, option_type, Target::Enum, 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;
String, sym::String, string, Target::Struct, GenericRequirement::None;
CStr, sym::CStr, c_str, Target::Struct, GenericRequirement::None;
}
pub enum GenericRequirement {
None,
Minimum(usize),
Exact(usize),
}
pub static FN_TRAITS: &'static [LangItem] = &[LangItem::Fn, LangItem::FnMut, LangItem::FnOnce];
pub static OPERATORS: &'static [LangItem] = &[
LangItem::Add,
LangItem::Sub,
LangItem::Mul,
LangItem::Div,
LangItem::Rem,
LangItem::Neg,
LangItem::Not,
LangItem::BitXor,
LangItem::BitAnd,
LangItem::BitOr,
LangItem::Shl,
LangItem::Shr,
LangItem::AddAssign,
LangItem::SubAssign,
LangItem::MulAssign,
LangItem::DivAssign,
LangItem::RemAssign,
LangItem::BitXorAssign,
LangItem::BitAndAssign,
LangItem::BitOrAssign,
LangItem::ShlAssign,
LangItem::ShrAssign,
LangItem::Index,
LangItem::IndexMut,
LangItem::PartialEq,
LangItem::PartialOrd,
];
|
