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1 | //! Defines language items. |
2 | //! | |
3 | //! Language items are items that represent concepts intrinsic to the language | |
4 | //! itself. Examples are: | |
5 | //! | |
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. | |
9 | ||
10 | pub use self::LangItem::*; | |
11 | ||
12 | use crate::def_id::DefId; | |
13 | use crate::Target; | |
14 | ||
15 | use rustc_ast::ast; | |
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}; | |
20 | use rustc_span::Span; | |
21 | ||
22 | use lazy_static::lazy_static; | |
23 | ||
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 { | |
27 | ( | |
28 | $( $variant:ident, $name:expr, $method:ident, $target:path; )* | |
29 | ) => { | |
30 | ||
31 | enum_from_u32! { | |
32 | /// A representation of all the valid language items in Rust. | |
33 | #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] | |
34 | pub enum LangItem { | |
35 | $($variant,)* | |
36 | } | |
37 | } | |
38 | ||
39 | impl LangItem { | |
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 { | |
44 | match self { | |
45 | $( $variant => $name, )* | |
46 | } | |
47 | } | |
48 | } | |
49 | ||
50 | #[derive(HashStable_Generic)] | |
51 | pub struct LanguageItems { | |
52 | /// Mappings from lang items to their possibly found `DefId`s. | |
53 | /// The index corresponds to the order in `LangItem`. | |
54 | pub items: Vec<Option<DefId>>, | |
55 | /// Lang items that were not found during collection. | |
56 | pub missing: Vec<LangItem>, | |
57 | } | |
58 | ||
59 | impl LanguageItems { | |
60 | /// Construct an empty collection of lang items and no missing ones. | |
61 | pub fn new() -> Self { | |
62 | fn init_none(_: LangItem) -> Option<DefId> { None } | |
63 | ||
64 | Self { | |
65 | items: vec![$(init_none($variant)),*], | |
66 | missing: Vec::new(), | |
67 | } | |
68 | } | |
69 | ||
70 | /// Returns the mappings to the possibly found `DefId`s for each lang item. | |
71 | pub fn items(&self) -> &[Option<DefId>] { | |
72 | &*self.items | |
73 | } | |
74 | ||
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())) | |
80 | } | |
81 | ||
82 | $( | |
83 | /// Returns the corresponding `DefId` for the lang item | |
84 | #[doc = $name] | |
85 | /// if it exists. | |
86 | #[allow(dead_code)] | |
87 | pub fn $method(&self) -> Option<DefId> { | |
88 | self.items[$variant as usize] | |
89 | } | |
90 | )* | |
91 | } | |
92 | ||
93 | lazy_static! { | |
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, $target)); )* | |
98 | item_refs | |
99 | }; | |
100 | } | |
101 | ||
102 | // End of the macro | |
103 | } | |
104 | } | |
105 | ||
106 | impl<CTX> HashStable<CTX> for LangItem { | |
107 | fn hash_stable(&self, _: &mut CTX, hasher: &mut StableHasher) { | |
108 | ::std::hash::Hash::hash(self, hasher); | |
109 | } | |
110 | } | |
111 | ||
112 | /// Extracts the first `lang = "$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| { | |
117 | Some(match 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), | |
121 | _ => return None, | |
122 | }) | |
123 | }) | |
124 | } | |
125 | ||
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; | |
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138 | ConstSlicePtrImplItem, "const_slice_ptr", const_slice_ptr_impl, Target::Impl; |
139 | MutSlicePtrImplItem, "mut_slice_ptr", mut_slice_ptr_impl, Target::Impl; | |
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140 | I8ImplItem, "i8", i8_impl, Target::Impl; |
141 | I16ImplItem, "i16", i16_impl, Target::Impl; | |
142 | I32ImplItem, "i32", i32_impl, Target::Impl; | |
143 | I64ImplItem, "i64", i64_impl, Target::Impl; | |
144 | I128ImplItem, "i128", i128_impl, Target::Impl; | |
145 | IsizeImplItem, "isize", isize_impl, Target::Impl; | |
146 | U8ImplItem, "u8", u8_impl, Target::Impl; | |
147 | U16ImplItem, "u16", u16_impl, Target::Impl; | |
148 | U32ImplItem, "u32", u32_impl, Target::Impl; | |
149 | U64ImplItem, "u64", u64_impl, Target::Impl; | |
150 | U128ImplItem, "u128", u128_impl, Target::Impl; | |
151 | UsizeImplItem, "usize", usize_impl, Target::Impl; | |
152 | F32ImplItem, "f32", f32_impl, Target::Impl; | |
153 | F64ImplItem, "f64", f64_impl, Target::Impl; | |
154 | F32RuntimeImplItem, "f32_runtime", f32_runtime_impl, Target::Impl; | |
155 | F64RuntimeImplItem, "f64_runtime", f64_runtime_impl, Target::Impl; | |
156 | ||
157 | SizedTraitLangItem, "sized", sized_trait, Target::Trait; | |
158 | UnsizeTraitLangItem, "unsize", unsize_trait, Target::Trait; | |
159 | // trait injected by #[derive(PartialEq)], (i.e. "Partial EQ"). | |
160 | StructuralPeqTraitLangItem, "structural_peq", structural_peq_trait, Target::Trait; | |
161 | // trait injected by #[derive(Eq)], (i.e. "Total EQ"; no, I will not apologize). | |
162 | StructuralTeqTraitLangItem, "structural_teq", structural_teq_trait, Target::Trait; | |
163 | CopyTraitLangItem, "copy", copy_trait, Target::Trait; | |
164 | CloneTraitLangItem, "clone", clone_trait, Target::Trait; | |
165 | SyncTraitLangItem, "sync", sync_trait, Target::Trait; | |
166 | FreezeTraitLangItem, "freeze", freeze_trait, Target::Trait; | |
167 | ||
168 | DropTraitLangItem, "drop", drop_trait, Target::Trait; | |
169 | ||
170 | CoerceUnsizedTraitLangItem, "coerce_unsized", coerce_unsized_trait, Target::Trait; | |
171 | DispatchFromDynTraitLangItem,"dispatch_from_dyn", dispatch_from_dyn_trait, Target::Trait; | |
172 | ||
173 | AddTraitLangItem, "add", add_trait, Target::Trait; | |
174 | SubTraitLangItem, "sub", sub_trait, Target::Trait; | |
175 | MulTraitLangItem, "mul", mul_trait, Target::Trait; | |
176 | DivTraitLangItem, "div", div_trait, Target::Trait; | |
177 | RemTraitLangItem, "rem", rem_trait, Target::Trait; | |
178 | NegTraitLangItem, "neg", neg_trait, Target::Trait; | |
179 | NotTraitLangItem, "not", not_trait, Target::Trait; | |
180 | BitXorTraitLangItem, "bitxor", bitxor_trait, Target::Trait; | |
181 | BitAndTraitLangItem, "bitand", bitand_trait, Target::Trait; | |
182 | BitOrTraitLangItem, "bitor", bitor_trait, Target::Trait; | |
183 | ShlTraitLangItem, "shl", shl_trait, Target::Trait; | |
184 | ShrTraitLangItem, "shr", shr_trait, Target::Trait; | |
185 | AddAssignTraitLangItem, "add_assign", add_assign_trait, Target::Trait; | |
186 | SubAssignTraitLangItem, "sub_assign", sub_assign_trait, Target::Trait; | |
187 | MulAssignTraitLangItem, "mul_assign", mul_assign_trait, Target::Trait; | |
188 | DivAssignTraitLangItem, "div_assign", div_assign_trait, Target::Trait; | |
189 | RemAssignTraitLangItem, "rem_assign", rem_assign_trait, Target::Trait; | |
190 | BitXorAssignTraitLangItem, "bitxor_assign", bitxor_assign_trait, Target::Trait; | |
191 | BitAndAssignTraitLangItem, "bitand_assign", bitand_assign_trait, Target::Trait; | |
192 | BitOrAssignTraitLangItem, "bitor_assign", bitor_assign_trait, Target::Trait; | |
193 | ShlAssignTraitLangItem, "shl_assign", shl_assign_trait, Target::Trait; | |
194 | ShrAssignTraitLangItem, "shr_assign", shr_assign_trait, Target::Trait; | |
195 | IndexTraitLangItem, "index", index_trait, Target::Trait; | |
196 | IndexMutTraitLangItem, "index_mut", index_mut_trait, Target::Trait; | |
197 | ||
198 | UnsafeCellTypeLangItem, "unsafe_cell", unsafe_cell_type, Target::Struct; | |
199 | VaListTypeLangItem, "va_list", va_list, Target::Struct; | |
200 | ||
201 | DerefTraitLangItem, "deref", deref_trait, Target::Trait; | |
202 | DerefMutTraitLangItem, "deref_mut", deref_mut_trait, Target::Trait; | |
203 | ReceiverTraitLangItem, "receiver", receiver_trait, Target::Trait; | |
204 | ||
205 | FnTraitLangItem, "fn", fn_trait, Target::Trait; | |
206 | FnMutTraitLangItem, "fn_mut", fn_mut_trait, Target::Trait; | |
207 | FnOnceTraitLangItem, "fn_once", fn_once_trait, Target::Trait; | |
208 | ||
209 | FutureTraitLangItem, "future_trait", future_trait, Target::Trait; | |
210 | GeneratorStateLangItem, "generator_state", gen_state, Target::Enum; | |
211 | GeneratorTraitLangItem, "generator", gen_trait, Target::Trait; | |
212 | UnpinTraitLangItem, "unpin", unpin_trait, Target::Trait; | |
213 | PinTypeLangItem, "pin", pin_type, Target::Struct; | |
214 | ||
215 | // Don't be fooled by the naming here: this lang item denotes `PartialEq`, not `Eq`. | |
216 | EqTraitLangItem, "eq", eq_trait, Target::Trait; | |
217 | PartialOrdTraitLangItem, "partial_ord", partial_ord_trait, Target::Trait; | |
218 | ||
219 | // A number of panic-related lang items. The `panic` item corresponds to | |
220 | // divide-by-zero and various panic cases with `match`. The | |
221 | // `panic_bounds_check` item is for indexing arrays. | |
222 | // | |
223 | // The `begin_unwind` lang item has a predefined symbol name and is sort of | |
224 | // a "weak lang item" in the sense that a crate is not required to have it | |
225 | // defined to use it, but a final product is required to define it | |
226 | // somewhere. Additionally, there are restrictions on crates that use a weak | |
227 | // lang item, but do not have it defined. | |
228 | PanicFnLangItem, "panic", panic_fn, Target::Fn; | |
229 | PanicBoundsCheckFnLangItem, "panic_bounds_check", panic_bounds_check_fn, Target::Fn; | |
230 | PanicInfoLangItem, "panic_info", panic_info, Target::Struct; | |
231 | PanicLocationLangItem, "panic_location", panic_location, Target::Struct; | |
232 | PanicImplLangItem, "panic_impl", panic_impl, Target::Fn; | |
233 | // Libstd panic entry point. Necessary for const eval to be able to catch it | |
234 | BeginPanicFnLangItem, "begin_panic", begin_panic_fn, Target::Fn; | |
235 | ||
236 | ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn, Target::Fn; | |
237 | BoxFreeFnLangItem, "box_free", box_free_fn, Target::Fn; | |
238 | DropInPlaceFnLangItem, "drop_in_place", drop_in_place_fn, Target::Fn; | |
239 | OomLangItem, "oom", oom, Target::Fn; | |
240 | AllocLayoutLangItem, "alloc_layout", alloc_layout, Target::Struct; | |
241 | ||
242 | StartFnLangItem, "start", start_fn, Target::Fn; | |
243 | ||
244 | EhPersonalityLangItem, "eh_personality", eh_personality, Target::Fn; | |
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245 | EhCatchTypeinfoLangItem, "eh_catch_typeinfo", eh_catch_typeinfo, Target::Static; |
246 | ||
247 | OwnedBoxLangItem, "owned_box", owned_box, Target::Struct; | |
248 | ||
249 | PhantomDataItem, "phantom_data", phantom_data, Target::Struct; | |
250 | ||
251 | ManuallyDropItem, "manually_drop", manually_drop, Target::Struct; | |
252 | ||
253 | MaybeUninitLangItem, "maybe_uninit", maybe_uninit, Target::Union; | |
254 | ||
255 | // Align offset for stride != 1; must not panic. | |
256 | AlignOffsetLangItem, "align_offset", align_offset_fn, Target::Fn; | |
257 | ||
258 | TerminationTraitLangItem, "termination", termination, Target::Trait; | |
74b04a01 | 259 | } |