302 lines
16 KiB
Rust
302 lines
16 KiB
Rust
//! Defines language items.
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//!
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//! Language items are items that represent concepts intrinsic to the language
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//! itself. Examples are:
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//!
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//! * Traits that specify "kinds"; e.g., `Sync`, `Send`.
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//! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`.
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//! * Functions called by the compiler itself.
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pub use self::LangItem::*;
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use crate::def_id::DefId;
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use crate::Target;
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use rustc_ast::ast;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
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use rustc_macros::HashStable_Generic;
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use rustc_span::symbol::{kw, sym, Symbol};
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use rustc_span::Span;
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use lazy_static::lazy_static;
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pub enum LangItemGroup {
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Op,
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}
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const NUM_GROUPS: usize = 1;
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macro_rules! expand_group {
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() => {
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None
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};
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($group:expr) => {
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Some($group)
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};
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}
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// The actual lang items defined come at the end of this file in one handy table.
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// So you probably just want to nip down to the end.
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macro_rules! language_item_table {
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(
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$( $variant:ident $($group:expr)?, $name:expr, $method:ident, $target:expr; )*
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) => {
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enum_from_u32! {
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/// A representation of all the valid language items in Rust.
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#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
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pub enum LangItem {
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$($variant,)*
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}
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}
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impl LangItem {
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/// Returns the `name` symbol in `#[lang = "$name"]`.
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/// For example, `LangItem::EqTraitLangItem`,
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/// that is `#[lang = "eq"]` would result in `sym::eq`.
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pub fn name(self) -> Symbol {
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match self {
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$( $variant => $name, )*
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}
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}
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pub fn group(self) -> Option<LangItemGroup> {
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use LangItemGroup::*;
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match self {
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$( $variant => expand_group!($($group)*), )*
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}
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}
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}
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#[derive(HashStable_Generic)]
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pub struct LanguageItems {
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/// Mappings from lang items to their possibly found `DefId`s.
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/// The index corresponds to the order in `LangItem`.
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pub items: Vec<Option<DefId>>,
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/// Lang items that were not found during collection.
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pub missing: Vec<LangItem>,
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/// Mapping from `LangItemGroup` discriminants to all
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/// `DefId`s of lang items in that group.
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pub groups: [Vec<DefId>; NUM_GROUPS],
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}
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impl LanguageItems {
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/// Construct an empty collection of lang items and no missing ones.
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pub fn new() -> Self {
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fn init_none(_: LangItem) -> Option<DefId> { None }
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Self {
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items: vec![$(init_none($variant)),*],
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missing: Vec::new(),
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groups: [vec![]; NUM_GROUPS],
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}
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}
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/// Returns the mappings to the possibly found `DefId`s for each lang item.
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pub fn items(&self) -> &[Option<DefId>] {
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&*self.items
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}
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/// Requires that a given `LangItem` was bound and returns the corresponding `DefId`.
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/// If it wasn't bound, e.g. due to a missing `#[lang = "<it.name()>"]`,
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/// returns an error message as a string.
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pub fn require(&self, it: LangItem) -> Result<DefId, String> {
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self.items[it as usize].ok_or_else(|| format!("requires `{}` lang_item", it.name()))
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}
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pub fn group(&self, group: LangItemGroup) -> &[DefId] {
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self.groups[group as usize].as_ref()
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}
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$(
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/// Returns the corresponding `DefId` for the lang item if it
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/// exists.
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#[allow(dead_code)]
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pub fn $method(&self) -> Option<DefId> {
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self.items[$variant as usize]
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}
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)*
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}
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lazy_static! {
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/// A mapping from the name of the lang item to its order and the form it must be of.
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pub static ref ITEM_REFS: FxHashMap<Symbol, (usize, Target)> = {
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let mut item_refs = FxHashMap::default();
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$( item_refs.insert($name, ($variant as usize, $target)); )*
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item_refs
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};
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}
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// End of the macro
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}
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}
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impl<CTX> HashStable<CTX> for LangItem {
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fn hash_stable(&self, _: &mut CTX, hasher: &mut StableHasher) {
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::std::hash::Hash::hash(self, hasher);
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}
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}
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/// Extracts the first `lang = "$name"` out of a list of attributes.
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/// The attributes `#[panic_handler]` and `#[alloc_error_handler]`
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/// are also extracted out when found.
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pub fn extract(attrs: &[ast::Attribute]) -> Option<(Symbol, Span)> {
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attrs.iter().find_map(|attr| {
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Some(match attr {
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_ if attr.check_name(sym::lang) => (attr.value_str()?, attr.span),
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_ if attr.check_name(sym::panic_handler) => (sym::panic_impl, attr.span),
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_ if attr.check_name(sym::alloc_error_handler) => (sym::oom, attr.span),
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_ => return None,
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})
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})
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}
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language_item_table! {
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// Variant name, Name, Method name, Target;
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BoolImplItem, sym::bool, bool_impl, Target::Impl;
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CharImplItem, sym::char, char_impl, Target::Impl;
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StrImplItem, sym::str, str_impl, Target::Impl;
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SliceImplItem, sym::slice, slice_impl, Target::Impl;
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SliceU8ImplItem, sym::slice_u8, slice_u8_impl, Target::Impl;
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StrAllocImplItem, sym::str_alloc, str_alloc_impl, Target::Impl;
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SliceAllocImplItem, sym::slice_alloc, slice_alloc_impl, Target::Impl;
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SliceU8AllocImplItem, sym::slice_u8_alloc, slice_u8_alloc_impl, Target::Impl;
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ConstPtrImplItem, sym::const_ptr, const_ptr_impl, Target::Impl;
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MutPtrImplItem, sym::mut_ptr, mut_ptr_impl, Target::Impl;
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ConstSlicePtrImplItem, sym::const_slice_ptr, const_slice_ptr_impl, Target::Impl;
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MutSlicePtrImplItem, sym::mut_slice_ptr, mut_slice_ptr_impl, Target::Impl;
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I8ImplItem, sym::i8, i8_impl, Target::Impl;
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I16ImplItem, sym::i16, i16_impl, Target::Impl;
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I32ImplItem, sym::i32, i32_impl, Target::Impl;
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I64ImplItem, sym::i64, i64_impl, Target::Impl;
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I128ImplItem, sym::i128, i128_impl, Target::Impl;
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IsizeImplItem, sym::isize, isize_impl, Target::Impl;
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U8ImplItem, sym::u8, u8_impl, Target::Impl;
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U16ImplItem, sym::u16, u16_impl, Target::Impl;
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U32ImplItem, sym::u32, u32_impl, Target::Impl;
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U64ImplItem, sym::u64, u64_impl, Target::Impl;
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U128ImplItem, sym::u128, u128_impl, Target::Impl;
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UsizeImplItem, sym::usize, usize_impl, Target::Impl;
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F32ImplItem, sym::f32, f32_impl, Target::Impl;
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F64ImplItem, sym::f64, f64_impl, Target::Impl;
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F32RuntimeImplItem, sym::f32_runtime, f32_runtime_impl, Target::Impl;
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F64RuntimeImplItem, sym::f64_runtime, f64_runtime_impl, Target::Impl;
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SizedTraitLangItem, sym::sized, sized_trait, Target::Trait;
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UnsizeTraitLangItem, sym::unsize, unsize_trait, Target::Trait;
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// trait injected by #[derive(PartialEq)], (i.e. "Partial EQ").
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StructuralPeqTraitLangItem, sym::structural_peq, structural_peq_trait, Target::Trait;
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// trait injected by #[derive(Eq)], (i.e. "Total EQ"; no, I will not apologize).
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StructuralTeqTraitLangItem, sym::structural_teq, structural_teq_trait, Target::Trait;
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CopyTraitLangItem, sym::copy, copy_trait, Target::Trait;
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CloneTraitLangItem, sym::clone, clone_trait, Target::Trait;
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SyncTraitLangItem, sym::sync, sync_trait, Target::Trait;
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DiscriminantKindTraitLangItem, sym::discriminant_kind, discriminant_kind_trait, Target::Trait;
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// The associated item of `trait DiscriminantKind`.
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DiscriminantTypeLangItem, sym::discriminant_type, discriminant_type, Target::AssocTy;
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FreezeTraitLangItem, sym::freeze, freeze_trait, Target::Trait;
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DropTraitLangItem, sym::drop, drop_trait, Target::Trait;
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CoerceUnsizedTraitLangItem, sym::coerce_unsized, coerce_unsized_trait, Target::Trait;
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DispatchFromDynTraitLangItem, sym::dispatch_from_dyn, dispatch_from_dyn_trait, Target::Trait;
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AddTraitLangItem(Op), sym::add, add_trait, Target::Trait;
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SubTraitLangItem(Op), sym::sub, sub_trait, Target::Trait;
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MulTraitLangItem(Op), sym::mul, mul_trait, Target::Trait;
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DivTraitLangItem(Op), sym::div, div_trait, Target::Trait;
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RemTraitLangItem(Op), sym::rem, rem_trait, Target::Trait;
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NegTraitLangItem(Op), sym::neg, neg_trait, Target::Trait;
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NotTraitLangItem(Op), sym::not, not_trait, Target::Trait;
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BitXorTraitLangItem(Op), sym::bitxor, bitxor_trait, Target::Trait;
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BitAndTraitLangItem(Op), sym::bitand, bitand_trait, Target::Trait;
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BitOrTraitLangItem(Op), sym::bitor, bitor_trait, Target::Trait;
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ShlTraitLangItem(Op), sym::shl, shl_trait, Target::Trait;
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ShrTraitLangItem(Op), sym::shr, shr_trait, Target::Trait;
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AddAssignTraitLangItem(Op), sym::add_assign, add_assign_trait, Target::Trait;
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SubAssignTraitLangItem(Op), sym::sub_assign, sub_assign_trait, Target::Trait;
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MulAssignTraitLangItem(Op), sym::mul_assign, mul_assign_trait, Target::Trait;
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DivAssignTraitLangItem(Op), sym::div_assign, div_assign_trait, Target::Trait;
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RemAssignTraitLangItem(Op), sym::rem_assign, rem_assign_trait, Target::Trait;
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BitXorAssignTraitLangItem(Op), sym::bitxor_assign, bitxor_assign_trait, Target::Trait;
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BitAndAssignTraitLangItem(Op), sym::bitand_assign, bitand_assign_trait, Target::Trait;
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BitOrAssignTraitLangItem(Op), sym::bitor_assign, bitor_assign_trait, Target::Trait;
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ShlAssignTraitLangItem(Op), sym::shl_assign, shl_assign_trait, Target::Trait;
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ShrAssignTraitLangItem(Op), sym::shr_assign, shr_assign_trait, Target::Trait;
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IndexTraitLangItem(Op), sym::index, index_trait, Target::Trait;
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IndexMutTraitLangItem(Op), sym::index_mut, index_mut_trait, Target::Trait;
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UnsafeCellTypeLangItem, sym::unsafe_cell, unsafe_cell_type, Target::Struct;
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VaListTypeLangItem, sym::va_list, va_list, Target::Struct;
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DerefTraitLangItem, sym::deref, deref_trait, Target::Trait;
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DerefMutTraitLangItem, sym::deref_mut, deref_mut_trait, Target::Trait;
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ReceiverTraitLangItem, sym::receiver, receiver_trait, Target::Trait;
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FnTraitLangItem, kw::Fn, fn_trait, Target::Trait;
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FnMutTraitLangItem, sym::fn_mut, fn_mut_trait, Target::Trait;
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FnOnceTraitLangItem, sym::fn_once, fn_once_trait, Target::Trait;
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FnOnceOutputLangItem, sym::fn_once_output, fn_once_output, Target::AssocTy;
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FutureTraitLangItem, sym::future_trait, future_trait, Target::Trait;
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GeneratorStateLangItem, sym::generator_state, gen_state, Target::Enum;
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GeneratorTraitLangItem, sym::generator, gen_trait, Target::Trait;
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UnpinTraitLangItem, sym::unpin, unpin_trait, Target::Trait;
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PinTypeLangItem, sym::pin, pin_type, Target::Struct;
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// Don't be fooled by the naming here: this lang item denotes `PartialEq`, not `Eq`.
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EqTraitLangItem, sym::eq, eq_trait, Target::Trait;
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PartialOrdTraitLangItem, sym::partial_ord, partial_ord_trait, Target::Trait;
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// A number of panic-related lang items. The `panic` item corresponds to
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// divide-by-zero and various panic cases with `match`. The
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// `panic_bounds_check` item is for indexing arrays.
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//
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// The `begin_unwind` lang item has a predefined symbol name and is sort of
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// a "weak lang item" in the sense that a crate is not required to have it
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// defined to use it, but a final product is required to define it
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// somewhere. Additionally, there are restrictions on crates that use a weak
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// lang item, but do not have it defined.
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PanicFnLangItem, sym::panic, panic_fn, Target::Fn;
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PanicBoundsCheckFnLangItem, sym::panic_bounds_check, panic_bounds_check_fn, Target::Fn;
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PanicInfoLangItem, sym::panic_info, panic_info, Target::Struct;
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PanicLocationLangItem, sym::panic_location, panic_location, Target::Struct;
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PanicImplLangItem, sym::panic_impl, panic_impl, Target::Fn;
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// Libstd panic entry point. Necessary for const eval to be able to catch it
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BeginPanicFnLangItem, sym::begin_panic, begin_panic_fn, Target::Fn;
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ExchangeMallocFnLangItem, sym::exchange_malloc, exchange_malloc_fn, Target::Fn;
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BoxFreeFnLangItem, sym::box_free, box_free_fn, Target::Fn;
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DropInPlaceFnLangItem, sym::drop_in_place, drop_in_place_fn, Target::Fn;
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OomLangItem, sym::oom, oom, Target::Fn;
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AllocLayoutLangItem, sym::alloc_layout, alloc_layout, Target::Struct;
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StartFnLangItem, sym::start, start_fn, Target::Fn;
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EhPersonalityLangItem, sym::eh_personality, eh_personality, Target::Fn;
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EhCatchTypeinfoLangItem, sym::eh_catch_typeinfo, eh_catch_typeinfo, Target::Static;
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OwnedBoxLangItem, sym::owned_box, owned_box, Target::Struct;
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PhantomDataItem, sym::phantom_data, phantom_data, Target::Struct;
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ManuallyDropItem, sym::manually_drop, manually_drop, Target::Struct;
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MaybeUninitLangItem, sym::maybe_uninit, maybe_uninit, Target::Union;
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// Align offset for stride != 1; must not panic.
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AlignOffsetLangItem, sym::align_offset, align_offset_fn, Target::Fn;
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TerminationTraitLangItem, sym::termination, termination, Target::Trait;
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TryTraitLangItem, kw::Try, try_trait, Target::Trait;
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// language items related to source code coverage instrumentation (-Zinstrument-coverage)
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CountCodeRegionFnLangItem, sym::count_code_region, count_code_region_fn, Target::Fn;
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CoverageCounterAddFnLangItem, sym::coverage_counter_add, coverage_counter_add_fn, Target::Fn;
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CoverageCounterSubtractFnLangItem, sym::coverage_counter_subtract, coverage_counter_subtract_fn, Target::Fn;
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}
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