hir_def/
lang_item.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
//! Collects lang items: items marked with `#[lang = "..."]` attribute.
//!
//! This attribute to tell the compiler about semi built-in std library
//! features, such as Fn family of traits.
use hir_expand::name::Name;
use intern::{sym, Symbol};
use rustc_hash::FxHashMap;
use triomphe::Arc;

use crate::{
    db::DefDatabase, path::Path, AdtId, AssocItemId, AttrDefId, CrateId, EnumId, EnumVariantId,
    FunctionId, ImplId, ModuleDefId, StaticId, StructId, TraitId, TypeAliasId, UnionId,
};

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum LangItemTarget {
    EnumId(EnumId),
    Function(FunctionId),
    ImplDef(ImplId),
    Static(StaticId),
    Struct(StructId),
    Union(UnionId),
    TypeAlias(TypeAliasId),
    Trait(TraitId),
    EnumVariant(EnumVariantId),
}

impl LangItemTarget {
    pub fn as_enum(self) -> Option<EnumId> {
        match self {
            LangItemTarget::EnumId(id) => Some(id),
            _ => None,
        }
    }

    pub fn as_function(self) -> Option<FunctionId> {
        match self {
            LangItemTarget::Function(id) => Some(id),
            _ => None,
        }
    }

    pub fn as_impl_def(self) -> Option<ImplId> {
        match self {
            LangItemTarget::ImplDef(id) => Some(id),
            _ => None,
        }
    }

    pub fn as_static(self) -> Option<StaticId> {
        match self {
            LangItemTarget::Static(id) => Some(id),
            _ => None,
        }
    }

    pub fn as_struct(self) -> Option<StructId> {
        match self {
            LangItemTarget::Struct(id) => Some(id),
            _ => None,
        }
    }

    pub fn as_trait(self) -> Option<TraitId> {
        match self {
            LangItemTarget::Trait(id) => Some(id),
            _ => None,
        }
    }

    pub fn as_enum_variant(self) -> Option<EnumVariantId> {
        match self {
            LangItemTarget::EnumVariant(id) => Some(id),
            _ => None,
        }
    }

    pub fn as_type_alias(self) -> Option<TypeAliasId> {
        match self {
            LangItemTarget::TypeAlias(id) => Some(id),
            _ => None,
        }
    }
}

#[derive(Default, Debug, Clone, PartialEq, Eq)]
pub struct LangItems {
    items: FxHashMap<LangItem, LangItemTarget>,
}

impl LangItems {
    pub fn target(&self, item: LangItem) -> Option<LangItemTarget> {
        self.items.get(&item).copied()
    }

    /// Salsa query. This will look for lang items in a specific crate.
    pub(crate) fn crate_lang_items_query(
        db: &dyn DefDatabase,
        krate: CrateId,
    ) -> Option<Arc<LangItems>> {
        let _p = tracing::info_span!("crate_lang_items_query").entered();

        let mut lang_items = LangItems::default();

        let crate_def_map = db.crate_def_map(krate);

        for (_, module_data) in crate_def_map.modules() {
            for impl_def in module_data.scope.impls() {
                lang_items.collect_lang_item(db, impl_def, LangItemTarget::ImplDef);
                for assoc in db.impl_data(impl_def).items.iter().copied() {
                    match assoc {
                        AssocItemId::FunctionId(f) => {
                            lang_items.collect_lang_item(db, f, LangItemTarget::Function)
                        }
                        AssocItemId::TypeAliasId(t) => {
                            lang_items.collect_lang_item(db, t, LangItemTarget::TypeAlias)
                        }
                        AssocItemId::ConstId(_) => (),
                    }
                }
            }

            for def in module_data.scope.declarations() {
                match def {
                    ModuleDefId::TraitId(trait_) => {
                        lang_items.collect_lang_item(db, trait_, LangItemTarget::Trait);
                        db.trait_data(trait_).items.iter().for_each(
                            |&(_, assoc_id)| match assoc_id {
                                AssocItemId::FunctionId(f) => {
                                    lang_items.collect_lang_item(db, f, LangItemTarget::Function);
                                }
                                AssocItemId::TypeAliasId(alias) => lang_items.collect_lang_item(
                                    db,
                                    alias,
                                    LangItemTarget::TypeAlias,
                                ),
                                AssocItemId::ConstId(_) => {}
                            },
                        );
                    }
                    ModuleDefId::AdtId(AdtId::EnumId(e)) => {
                        lang_items.collect_lang_item(db, e, LangItemTarget::EnumId);
                        crate_def_map.enum_definitions[&e].iter().for_each(|&id| {
                            lang_items.collect_lang_item(db, id, LangItemTarget::EnumVariant);
                        });
                    }
                    ModuleDefId::AdtId(AdtId::StructId(s)) => {
                        lang_items.collect_lang_item(db, s, LangItemTarget::Struct);
                    }
                    ModuleDefId::AdtId(AdtId::UnionId(u)) => {
                        lang_items.collect_lang_item(db, u, LangItemTarget::Union);
                    }
                    ModuleDefId::FunctionId(f) => {
                        lang_items.collect_lang_item(db, f, LangItemTarget::Function);
                    }
                    ModuleDefId::StaticId(s) => {
                        lang_items.collect_lang_item(db, s, LangItemTarget::Static);
                    }
                    ModuleDefId::TypeAliasId(t) => {
                        lang_items.collect_lang_item(db, t, LangItemTarget::TypeAlias);
                    }
                    _ => {}
                }
            }
        }

        if lang_items.items.is_empty() {
            None
        } else {
            Some(Arc::new(lang_items))
        }
    }

    /// Salsa query. Look for a lang item, starting from the specified crate and recursively
    /// traversing its dependencies.
    pub(crate) fn lang_item_query(
        db: &dyn DefDatabase,
        start_crate: CrateId,
        item: LangItem,
    ) -> Option<LangItemTarget> {
        let _p = tracing::info_span!("lang_item_query").entered();
        if let Some(target) =
            db.crate_lang_items(start_crate).and_then(|it| it.items.get(&item).copied())
        {
            return Some(target);
        }
        db.crate_graph()[start_crate]
            .dependencies
            .iter()
            .find_map(|dep| db.lang_item(dep.crate_id, item))
    }

    fn collect_lang_item<T>(
        &mut self,
        db: &dyn DefDatabase,
        item: T,
        constructor: fn(T) -> LangItemTarget,
    ) where
        T: Into<AttrDefId> + Copy,
    {
        let _p = tracing::info_span!("collect_lang_item").entered();
        if let Some(lang_item) = lang_attr(db, item.into()) {
            self.items.entry(lang_item).or_insert_with(|| constructor(item));
        }
    }
}

pub(crate) fn lang_attr(db: &dyn DefDatabase, item: AttrDefId) -> Option<LangItem> {
    db.attrs(item).lang_item()
}

pub(crate) fn notable_traits_in_deps(
    db: &dyn DefDatabase,
    krate: CrateId,
) -> Arc<[Arc<[TraitId]>]> {
    let _p = tracing::info_span!("notable_traits_in_deps", ?krate).entered();
    let crate_graph = db.crate_graph();

    Arc::from_iter(
        crate_graph.transitive_deps(krate).filter_map(|krate| db.crate_notable_traits(krate)),
    )
}

pub(crate) fn crate_notable_traits(db: &dyn DefDatabase, krate: CrateId) -> Option<Arc<[TraitId]>> {
    let _p = tracing::info_span!("crate_notable_traits", ?krate).entered();

    let mut traits = Vec::new();

    let crate_def_map = db.crate_def_map(krate);

    for (_, module_data) in crate_def_map.modules() {
        for def in module_data.scope.declarations() {
            if let ModuleDefId::TraitId(trait_) = def {
                if db.attrs(trait_.into()).has_doc_notable_trait() {
                    traits.push(trait_);
                }
            }
        }
    }

    if traits.is_empty() {
        None
    } else {
        Some(traits.into_iter().collect())
    }
}

pub enum GenericRequirement {
    None,
    Minimum(usize),
    Exact(usize),
}

macro_rules! language_item_table {
    (
        $( $(#[$attr:meta])* $variant:ident, $module:ident :: $name:ident, $method:ident, $target:expr, $generics:expr; )*
    ) => {

        /// A representation of all the valid language items in Rust.
        #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
        pub enum LangItem {
            $(
                #[doc = concat!("The `", stringify!($name), "` lang item.")]
                $(#[$attr])*
                $variant,
            )*
        }

        impl LangItem {
            pub fn name(self) -> &'static str {
                match self {
                    $( LangItem::$variant => stringify!($name), )*
                }
            }

            /// Opposite of [`LangItem::name`]
            pub fn from_symbol(sym: &Symbol) -> Option<Self> {
                match sym {
                    $(sym if *sym == $module::$name => Some(LangItem::$variant), )*
                    _ => None,
                }
            }
        }
    }
}

impl LangItem {
    /// Opposite of [`LangItem::name`]
    pub fn from_name(name: &hir_expand::name::Name) -> Option<Self> {
        Self::from_symbol(name.symbol())
    }

    pub fn path(&self, db: &dyn DefDatabase, start_crate: CrateId) -> Option<Path> {
        let t = db.lang_item(start_crate, *self)?;
        Some(Path::LangItem(t, None))
    }

    pub fn ty_rel_path(
        &self,
        db: &dyn DefDatabase,
        start_crate: CrateId,
        seg: Name,
    ) -> Option<Path> {
        let t = db.lang_item(start_crate, *self)?;
        Some(Path::LangItem(t, Some(seg)))
    }
}

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,                      sym::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);
    AsyncFn,                 sym::async_fn,            async_fn_trait,             Target::Trait,          GenericRequirement::Exact(1);
    AsyncFnMut,              sym::async_fn_mut,        async_fn_mut_trait,         Target::Trait,          GenericRequirement::Exact(1);
    AsyncFnOnce,             sym::async_fn_once,       async_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);
    CoroutineState,          sym::coroutine_state,     coroutine_state,            Target::Enum,           GenericRequirement::None;
    Coroutine,               sym::coroutine,           coroutine_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;
    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);
    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);

    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;
    FutureOutput,            sym::future_output,       future_output,              Target::TypeAlias,      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;
    Iterator,                sym::iterator,            iterator,                   Target::Trait,           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;
}