1 //! Defines language items.
3 //! Language items are items that represent concepts intrinsic to the language
4 //! itself. Examples are:
6 //! * Traits that specify "kinds"; e.g., `Sync`, `Send`.
7 //! * Traits that represent operators; e.g., `Add`, `Sub`, `Index`.
8 //! * Functions called by the compiler itself.
10 pub use self::LangItem::*;
12 use crate::def_id::DefId;
16 use rustc_data_structures::fx::FxHashMap;
17 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
18 use rustc_macros::HashStable_Generic;
19 use rustc_span::symbol::{sym, Symbol};
22 use lazy_static::lazy_static;
24 // The actual lang items defined come at the end of this file in one handy table.
25 // So you probably just want to nip down to the end.
26 macro_rules! language_item_table {
28 $( $variant:ident, $name:expr, $method:ident, $target:path; )*
32 /// A representation of all the valid language items in Rust.
33 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
40 /// Returns the `name` in `#[lang = "$name"]`.
41 /// For example, `LangItem::EqTraitLangItem`,
42 /// that is `#[lang = "eq"]` would result in `"eq"`.
43 pub fn name(self) -> &'static str {
45 $( $variant => $name, )*
50 #[derive(HashStable_Generic)]
51 pub struct LanguageItems {
52 /// Mappings from lang items to their possibly found `DefId`s.
53 /// The index corresponds to the order in `LangItem`.
54 pub items: Vec<Option<DefId>>,
55 /// Lang items that were not found during collection.
56 pub missing: Vec<LangItem>,
60 /// Construct an empty collection of lang items and no missing ones.
61 pub fn new() -> Self {
62 fn init_none(_: LangItem) -> Option<DefId> { None }
65 items: vec![$(init_none($variant)),*],
70 /// Returns the mappings to the possibly found `DefId`s for each lang item.
71 pub fn items(&self) -> &[Option<DefId>] {
75 /// Requires that a given `LangItem` was bound and returns the corresponding `DefId`.
76 /// If it wasn't bound, e.g. due to a missing `#[lang = "<it.name()>"]`,
77 /// returns an error message as a string.
78 pub fn require(&self, it: LangItem) -> Result<DefId, String> {
79 self.items[it as usize].ok_or_else(|| format!("requires `{}` lang_item", it.name()))
83 /// Returns the corresponding `DefId` for the lang item
87 pub fn $method(&self) -> Option<DefId> {
88 self.items[$variant as usize]
94 /// A mapping from the name of the lang item to its order and the form it must be of.
95 pub static ref ITEM_REFS: FxHashMap<&'static str, (usize, Target)> = {
96 let mut item_refs = FxHashMap::default();
97 $( item_refs.insert($name, ($variant as usize, $target)); )*
106 impl<CTX> HashStable<CTX> for LangItem {
107 fn hash_stable(&self, _: &mut CTX, hasher: &mut StableHasher) {
108 ::std::hash::Hash::hash(self, hasher);
112 /// Extracts the first `lang = "$name"` out of a list of attributes.
113 /// The attributes `#[panic_handler]` and `#[alloc_error_handler]`
114 /// are also extracted out when found.
115 pub fn extract(attrs: &[ast::Attribute]) -> Option<(Symbol, Span)> {
116 attrs.iter().find_map(|attr| {
118 _ if attr.check_name(sym::lang) => (attr.value_str()?, attr.span),
119 _ if attr.check_name(sym::panic_handler) => (sym::panic_impl, attr.span),
120 _ if attr.check_name(sym::alloc_error_handler) => (sym::oom, attr.span),
126 language_item_table! {
127 // Variant name, Name, Method name, Target;
128 BoolImplItem, "bool", bool_impl, Target::Impl;
129 CharImplItem, "char", char_impl, Target::Impl;
130 StrImplItem, "str", str_impl, Target::Impl;
131 SliceImplItem, "slice", slice_impl, Target::Impl;
132 SliceU8ImplItem, "slice_u8", slice_u8_impl, Target::Impl;
133 StrAllocImplItem, "str_alloc", str_alloc_impl, Target::Impl;
134 SliceAllocImplItem, "slice_alloc", slice_alloc_impl, Target::Impl;
135 SliceU8AllocImplItem, "slice_u8_alloc", slice_u8_alloc_impl, Target::Impl;
136 ConstPtrImplItem, "const_ptr", const_ptr_impl, Target::Impl;
137 MutPtrImplItem, "mut_ptr", mut_ptr_impl, Target::Impl;
138 I8ImplItem, "i8", i8_impl, Target::Impl;
139 I16ImplItem, "i16", i16_impl, Target::Impl;
140 I32ImplItem, "i32", i32_impl, Target::Impl;
141 I64ImplItem, "i64", i64_impl, Target::Impl;
142 I128ImplItem, "i128", i128_impl, Target::Impl;
143 IsizeImplItem, "isize", isize_impl, Target::Impl;
144 U8ImplItem, "u8", u8_impl, Target::Impl;
145 U16ImplItem, "u16", u16_impl, Target::Impl;
146 U32ImplItem, "u32", u32_impl, Target::Impl;
147 U64ImplItem, "u64", u64_impl, Target::Impl;
148 U128ImplItem, "u128", u128_impl, Target::Impl;
149 UsizeImplItem, "usize", usize_impl, Target::Impl;
150 F32ImplItem, "f32", f32_impl, Target::Impl;
151 F64ImplItem, "f64", f64_impl, Target::Impl;
152 F32RuntimeImplItem, "f32_runtime", f32_runtime_impl, Target::Impl;
153 F64RuntimeImplItem, "f64_runtime", f64_runtime_impl, Target::Impl;
155 SizedTraitLangItem, "sized", sized_trait, Target::Trait;
156 UnsizeTraitLangItem, "unsize", unsize_trait, Target::Trait;
157 // trait injected by #[derive(PartialEq)], (i.e. "Partial EQ").
158 StructuralPeqTraitLangItem, "structural_peq", structural_peq_trait, Target::Trait;
159 // trait injected by #[derive(Eq)], (i.e. "Total EQ"; no, I will not apologize).
160 StructuralTeqTraitLangItem, "structural_teq", structural_teq_trait, Target::Trait;
161 CopyTraitLangItem, "copy", copy_trait, Target::Trait;
162 CloneTraitLangItem, "clone", clone_trait, Target::Trait;
163 SyncTraitLangItem, "sync", sync_trait, Target::Trait;
164 FreezeTraitLangItem, "freeze", freeze_trait, Target::Trait;
166 DropTraitLangItem, "drop", drop_trait, Target::Trait;
168 CoerceUnsizedTraitLangItem, "coerce_unsized", coerce_unsized_trait, Target::Trait;
169 DispatchFromDynTraitLangItem,"dispatch_from_dyn", dispatch_from_dyn_trait, Target::Trait;
171 AddTraitLangItem, "add", add_trait, Target::Trait;
172 SubTraitLangItem, "sub", sub_trait, Target::Trait;
173 MulTraitLangItem, "mul", mul_trait, Target::Trait;
174 DivTraitLangItem, "div", div_trait, Target::Trait;
175 RemTraitLangItem, "rem", rem_trait, Target::Trait;
176 NegTraitLangItem, "neg", neg_trait, Target::Trait;
177 NotTraitLangItem, "not", not_trait, Target::Trait;
178 BitXorTraitLangItem, "bitxor", bitxor_trait, Target::Trait;
179 BitAndTraitLangItem, "bitand", bitand_trait, Target::Trait;
180 BitOrTraitLangItem, "bitor", bitor_trait, Target::Trait;
181 ShlTraitLangItem, "shl", shl_trait, Target::Trait;
182 ShrTraitLangItem, "shr", shr_trait, Target::Trait;
183 AddAssignTraitLangItem, "add_assign", add_assign_trait, Target::Trait;
184 SubAssignTraitLangItem, "sub_assign", sub_assign_trait, Target::Trait;
185 MulAssignTraitLangItem, "mul_assign", mul_assign_trait, Target::Trait;
186 DivAssignTraitLangItem, "div_assign", div_assign_trait, Target::Trait;
187 RemAssignTraitLangItem, "rem_assign", rem_assign_trait, Target::Trait;
188 BitXorAssignTraitLangItem, "bitxor_assign", bitxor_assign_trait, Target::Trait;
189 BitAndAssignTraitLangItem, "bitand_assign", bitand_assign_trait, Target::Trait;
190 BitOrAssignTraitLangItem, "bitor_assign", bitor_assign_trait, Target::Trait;
191 ShlAssignTraitLangItem, "shl_assign", shl_assign_trait, Target::Trait;
192 ShrAssignTraitLangItem, "shr_assign", shr_assign_trait, Target::Trait;
193 IndexTraitLangItem, "index", index_trait, Target::Trait;
194 IndexMutTraitLangItem, "index_mut", index_mut_trait, Target::Trait;
196 UnsafeCellTypeLangItem, "unsafe_cell", unsafe_cell_type, Target::Struct;
197 VaListTypeLangItem, "va_list", va_list, Target::Struct;
199 DerefTraitLangItem, "deref", deref_trait, Target::Trait;
200 DerefMutTraitLangItem, "deref_mut", deref_mut_trait, Target::Trait;
201 ReceiverTraitLangItem, "receiver", receiver_trait, Target::Trait;
203 FnTraitLangItem, "fn", fn_trait, Target::Trait;
204 FnMutTraitLangItem, "fn_mut", fn_mut_trait, Target::Trait;
205 FnOnceTraitLangItem, "fn_once", fn_once_trait, Target::Trait;
207 FutureTraitLangItem, "future_trait", future_trait, Target::Trait;
208 GeneratorStateLangItem, "generator_state", gen_state, Target::Enum;
209 GeneratorTraitLangItem, "generator", gen_trait, Target::Trait;
210 UnpinTraitLangItem, "unpin", unpin_trait, Target::Trait;
211 PinTypeLangItem, "pin", pin_type, Target::Struct;
213 // Don't be fooled by the naming here: this lang item denotes `PartialEq`, not `Eq`.
214 EqTraitLangItem, "eq", eq_trait, Target::Trait;
215 PartialOrdTraitLangItem, "partial_ord", partial_ord_trait, Target::Trait;
217 // A number of panic-related lang items. The `panic` item corresponds to
218 // divide-by-zero and various panic cases with `match`. The
219 // `panic_bounds_check` item is for indexing arrays.
221 // The `begin_unwind` lang item has a predefined symbol name and is sort of
222 // a "weak lang item" in the sense that a crate is not required to have it
223 // defined to use it, but a final product is required to define it
224 // somewhere. Additionally, there are restrictions on crates that use a weak
225 // lang item, but do not have it defined.
226 PanicFnLangItem, "panic", panic_fn, Target::Fn;
227 PanicBoundsCheckFnLangItem, "panic_bounds_check", panic_bounds_check_fn, Target::Fn;
228 PanicInfoLangItem, "panic_info", panic_info, Target::Struct;
229 PanicLocationLangItem, "panic_location", panic_location, Target::Struct;
230 PanicImplLangItem, "panic_impl", panic_impl, Target::Fn;
231 // Libstd panic entry point. Necessary for const eval to be able to catch it
232 BeginPanicFnLangItem, "begin_panic", begin_panic_fn, Target::Fn;
234 ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn, Target::Fn;
235 BoxFreeFnLangItem, "box_free", box_free_fn, Target::Fn;
236 DropInPlaceFnLangItem, "drop_in_place", drop_in_place_fn, Target::Fn;
237 OomLangItem, "oom", oom, Target::Fn;
238 AllocLayoutLangItem, "alloc_layout", alloc_layout, Target::Struct;
240 StartFnLangItem, "start", start_fn, Target::Fn;
242 EhPersonalityLangItem, "eh_personality", eh_personality, Target::Fn;
243 EhUnwindResumeLangItem, "eh_unwind_resume", eh_unwind_resume, Target::Fn;
244 EhCatchTypeinfoLangItem, "eh_catch_typeinfo", eh_catch_typeinfo, Target::Static;
246 OwnedBoxLangItem, "owned_box", owned_box, Target::Struct;
248 PhantomDataItem, "phantom_data", phantom_data, Target::Struct;
250 ManuallyDropItem, "manually_drop", manually_drop, Target::Struct;
252 MaybeUninitLangItem, "maybe_uninit", maybe_uninit, Target::Union;
254 // Align offset for stride != 1; must not panic.
255 AlignOffsetLangItem, "align_offset", align_offset_fn, Target::Fn;
257 TerminationTraitLangItem, "termination", termination, Target::Trait;
259 Arc, "arc", arc, Target::Struct;
260 Rc, "rc", rc, Target::Struct;