1 //! Methods for lowering the HIR to types. There are two main cases here:
3 //! - Lowering a type reference like `&usize` or `Option<foo::bar::Baz>` to a
4 //! type: The entry point for this is `Ty::from_hir`.
5 //! - Building the type for an item: This happens through the `type_for_def` query.
7 //! This usually involves resolving names, collecting generic arguments etc.
8 use std::cell::{Cell, RefCell};
9 use std::{iter, sync::Arc};
12 use chalk_ir::{cast::Cast, fold::Shift, interner::HasInterner, Mutability, Safety};
13 use hir_def::intern::Interned;
16 body::{Expander, LowerCtx},
17 builtin_type::BuiltinType,
18 generics::{TypeParamProvenance, WherePredicate, WherePredicateTypeTarget},
19 path::{GenericArg, Path, PathSegment, PathSegments},
20 resolver::{HasResolver, Resolver, TypeNs},
21 type_ref::{TraitBoundModifier, TraitRef as HirTraitRef, TypeBound, TypeRef},
22 AdtId, AssocContainerId, AssocItemId, ConstId, ConstParamId, EnumId, EnumVariantId, FunctionId,
23 GenericDefId, HasModule, ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId,
24 TypeAliasId, TypeParamId, UnionId, VariantId,
26 use hir_expand::{name::Name, ExpandResult};
27 use la_arena::ArenaMap;
28 use rustc_hash::FxHashSet;
29 use smallvec::SmallVec;
37 static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx,
39 all_super_trait_refs, associated_type_by_name_including_super_traits, generics, Generics,
41 AliasEq, AliasTy, Binders, BoundVar, CallableSig, DebruijnIndex, DynTy, FnPointer, FnSig,
42 FnSubst, ImplTraitId, Interner, PolyFnSig, ProjectionTy, QuantifiedWhereClause,
43 QuantifiedWhereClauses, ReturnTypeImplTrait, ReturnTypeImplTraits, Substitution,
44 TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyKind, WhereClause,
48 pub struct TyLoweringContext<'a> {
49 pub db: &'a dyn HirDatabase,
50 pub resolver: &'a Resolver,
51 in_binders: DebruijnIndex,
52 /// Note: Conceptually, it's thinkable that we could be in a location where
53 /// some type params should be represented as placeholders, and others
54 /// should be converted to variables. I think in practice, this isn't
55 /// possible currently, so this should be fine for now.
56 pub type_param_mode: TypeParamLoweringMode,
57 pub impl_trait_mode: ImplTraitLoweringMode,
58 impl_trait_counter: Cell<u16>,
59 /// When turning `impl Trait` into opaque types, we have to collect the
60 /// bounds at the same time to get the IDs correct (without becoming too
61 /// complicated). I don't like using interior mutability (as for the
62 /// counter), but I've tried and failed to make the lifetimes work for
63 /// passing around a `&mut TyLoweringContext`. The core problem is that
64 /// we're grouping the mutable data (the counter and this field) together
65 /// with the immutable context (the references to the DB and resolver).
66 /// Splitting this up would be a possible fix.
67 opaque_type_data: RefCell<Vec<ReturnTypeImplTrait>>,
68 expander: RefCell<Option<Expander>>,
69 /// Tracks types with explicit `?Sized` bounds.
70 pub(crate) unsized_types: RefCell<FxHashSet<Ty>>,
73 impl<'a> TyLoweringContext<'a> {
74 pub fn new(db: &'a dyn HirDatabase, resolver: &'a Resolver) -> Self {
75 let impl_trait_counter = Cell::new(0);
76 let impl_trait_mode = ImplTraitLoweringMode::Disallowed;
77 let type_param_mode = TypeParamLoweringMode::Placeholder;
78 let in_binders = DebruijnIndex::INNERMOST;
79 let opaque_type_data = RefCell::new(Vec::new());
88 expander: RefCell::new(None),
89 unsized_types: RefCell::default(),
93 pub fn with_debruijn<T>(
95 debruijn: DebruijnIndex,
96 f: impl FnOnce(&TyLoweringContext) -> T,
98 let opaque_ty_data_vec = self.opaque_type_data.replace(Vec::new());
99 let expander = self.expander.replace(None);
100 let unsized_types = self.unsized_types.replace(Default::default());
102 in_binders: debruijn,
103 impl_trait_counter: Cell::new(self.impl_trait_counter.get()),
104 opaque_type_data: RefCell::new(opaque_ty_data_vec),
105 expander: RefCell::new(expander),
106 unsized_types: RefCell::new(unsized_types),
109 let result = f(&new_ctx);
110 self.impl_trait_counter.set(new_ctx.impl_trait_counter.get());
111 self.opaque_type_data.replace(new_ctx.opaque_type_data.into_inner());
112 self.expander.replace(new_ctx.expander.into_inner());
113 self.unsized_types.replace(new_ctx.unsized_types.into_inner());
117 pub fn with_shifted_in<T>(
119 debruijn: DebruijnIndex,
120 f: impl FnOnce(&TyLoweringContext) -> T,
122 self.with_debruijn(self.in_binders.shifted_in_from(debruijn), f)
125 pub fn with_impl_trait_mode(self, impl_trait_mode: ImplTraitLoweringMode) -> Self {
126 Self { impl_trait_mode, ..self }
129 pub fn with_type_param_mode(self, type_param_mode: TypeParamLoweringMode) -> Self {
130 Self { type_param_mode, ..self }
134 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
135 pub enum ImplTraitLoweringMode {
136 /// `impl Trait` gets lowered into an opaque type that doesn't unify with
137 /// anything except itself. This is used in places where values flow 'out',
138 /// i.e. for arguments of the function we're currently checking, and return
139 /// types of functions we're calling.
141 /// `impl Trait` gets lowered into a type variable. Used for argument
142 /// position impl Trait when inside the respective function, since it allows
143 /// us to support that without Chalk.
145 /// `impl Trait` gets lowered into a variable that can unify with some
146 /// type. This is used in places where values flow 'in', i.e. for arguments
147 /// of functions we're calling, and the return type of the function we're
148 /// currently checking.
150 /// `impl Trait` is disallowed and will be an error.
154 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
155 pub enum TypeParamLoweringMode {
160 impl<'a> TyLoweringContext<'a> {
161 pub fn lower_ty(&self, type_ref: &TypeRef) -> Ty {
162 self.lower_ty_ext(type_ref).0
165 pub fn lower_ty_ext(&self, type_ref: &TypeRef) -> (Ty, Option<TypeNs>) {
167 let ty = match type_ref {
168 TypeRef::Never => TyKind::Never.intern(&Interner),
169 TypeRef::Tuple(inner) => {
170 let inner_tys = inner.iter().map(|tr| self.lower_ty(tr));
171 TyKind::Tuple(inner_tys.len(), Substitution::from_iter(&Interner, inner_tys))
174 TypeRef::Path(path) => {
175 let (ty, res_) = self.lower_path(path);
179 TypeRef::RawPtr(inner, mutability) => {
180 let inner_ty = self.lower_ty(inner);
181 TyKind::Raw(lower_to_chalk_mutability(*mutability), inner_ty).intern(&Interner)
183 TypeRef::Array(inner, len) => {
184 let inner_ty = self.lower_ty(inner);
186 let const_len = consteval::usize_const(len.as_usize());
188 TyKind::Array(inner_ty, const_len).intern(&Interner)
190 TypeRef::Slice(inner) => {
191 let inner_ty = self.lower_ty(inner);
192 TyKind::Slice(inner_ty).intern(&Interner)
194 TypeRef::Reference(inner, _, mutability) => {
195 let inner_ty = self.lower_ty(inner);
196 let lifetime = static_lifetime();
197 TyKind::Ref(lower_to_chalk_mutability(*mutability), lifetime, inner_ty)
200 TypeRef::Placeholder => TyKind::Error.intern(&Interner),
201 TypeRef::Fn(params, is_varargs) => {
202 let substs = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
203 Substitution::from_iter(&Interner, params.iter().map(|tr| ctx.lower_ty(tr)))
205 TyKind::Function(FnPointer {
206 num_binders: 0, // FIXME lower `for<'a> fn()` correctly
207 sig: FnSig { abi: (), safety: Safety::Safe, variadic: *is_varargs },
208 substitution: FnSubst(substs),
212 TypeRef::DynTrait(bounds) => {
214 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(&Interner);
215 let bounds = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
216 QuantifiedWhereClauses::from_iter(
218 bounds.iter().flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false)),
221 let bounds = crate::make_only_type_binders(1, bounds);
222 TyKind::Dyn(DynTy { bounds, lifetime: static_lifetime() }).intern(&Interner)
224 TypeRef::ImplTrait(bounds) => {
225 match self.impl_trait_mode {
226 ImplTraitLoweringMode::Opaque => {
227 let idx = self.impl_trait_counter.get();
228 self.impl_trait_counter.set(idx + 1);
229 let func = match self.resolver.generic_def() {
230 Some(GenericDefId::FunctionId(f)) => f,
231 _ => panic!("opaque impl trait lowering in non-function"),
234 assert!(idx as usize == self.opaque_type_data.borrow().len());
235 // this dance is to make sure the data is in the right
236 // place even if we encounter more opaque types while
237 // lowering the bounds
238 self.opaque_type_data.borrow_mut().push(ReturnTypeImplTrait {
239 bounds: crate::make_only_type_binders(1, Vec::new()),
241 // We don't want to lower the bounds inside the binders
242 // we're currently in, because they don't end up inside
243 // those binders. E.g. when we have `impl Trait<impl
244 // OtherTrait<T>>`, the `impl OtherTrait<T>` can't refer
245 // to the self parameter from `impl Trait`, and the
246 // bounds aren't actually stored nested within each
247 // other, but separately. So if the `T` refers to a type
248 // parameter of the outer function, it's just one binder
249 // away instead of two.
250 let actual_opaque_type_data = self
251 .with_debruijn(DebruijnIndex::INNERMOST, |ctx| {
252 ctx.lower_impl_trait(bounds, func)
254 self.opaque_type_data.borrow_mut()[idx as usize] = actual_opaque_type_data;
256 let impl_trait_id = ImplTraitId::ReturnTypeImplTrait(func, idx);
257 let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into();
258 let generics = generics(self.db.upcast(), func.into());
259 let parameters = generics.bound_vars_subst(self.in_binders);
260 TyKind::OpaqueType(opaque_ty_id, parameters).intern(&Interner)
262 ImplTraitLoweringMode::Param => {
263 let idx = self.impl_trait_counter.get();
264 // FIXME we're probably doing something wrong here
265 self.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
266 if let Some(def) = self.resolver.generic_def() {
267 let generics = generics(self.db.upcast(), def);
270 .filter(|(_, data)| {
271 data.provenance == TypeParamProvenance::ArgumentImplTrait
274 .map_or(TyKind::Error, |(id, _)| {
275 TyKind::Placeholder(to_placeholder_idx(self.db, id))
277 param.intern(&Interner)
279 TyKind::Error.intern(&Interner)
282 ImplTraitLoweringMode::Variable => {
283 let idx = self.impl_trait_counter.get();
284 // FIXME we're probably doing something wrong here
285 self.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
286 let (parent_params, self_params, list_params, _impl_trait_params) =
287 if let Some(def) = self.resolver.generic_def() {
288 let generics = generics(self.db.upcast(), def);
289 generics.provenance_split()
293 TyKind::BoundVar(BoundVar::new(
295 idx as usize + parent_params + self_params + list_params,
299 ImplTraitLoweringMode::Disallowed => {
300 // FIXME: report error
301 TyKind::Error.intern(&Interner)
305 TypeRef::Macro(macro_call) => {
306 let (expander, recursion_start) = {
307 let mut expander = self.expander.borrow_mut();
308 if expander.is_some() {
309 (Some(expander), false)
311 if let Some(module_id) = self.resolver.module() {
312 *expander = Some(Expander::new(
317 (Some(expander), true)
323 let ty = if let Some(mut expander) = expander {
324 let expander_mut = expander.as_mut().unwrap();
325 let macro_call = macro_call.to_node(self.db.upcast());
326 match expander_mut.enter_expand::<ast::Type>(self.db.upcast(), macro_call) {
327 Ok(ExpandResult { value: Some((mark, expanded)), .. }) => {
329 LowerCtx::new(self.db.upcast(), expander_mut.current_file_id());
330 let type_ref = TypeRef::from_ast(&ctx, expanded);
333 let ty = self.lower_ty(&type_ref);
339 .exit(self.db.upcast(), mark);
348 *self.expander.borrow_mut() = None;
350 ty.unwrap_or_else(|| TyKind::Error.intern(&Interner))
352 TypeRef::Error => TyKind::Error.intern(&Interner),
357 /// This is only for `generic_predicates_for_param`, where we can't just
358 /// lower the self types of the predicates since that could lead to cycles.
359 /// So we just check here if the `type_ref` resolves to a generic param, and which.
360 fn lower_ty_only_param(&self, type_ref: &TypeRef) -> Option<TypeParamId> {
361 let path = match type_ref {
362 TypeRef::Path(path) => path,
365 if path.type_anchor().is_some() {
368 if path.segments().len() > 1 {
372 match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
373 Some((it, None)) => it,
376 if let TypeNs::GenericParam(param_id) = resolution {
383 pub(crate) fn lower_ty_relative_path(
386 // We need the original resolution to lower `Self::AssocTy` correctly
388 remaining_segments: PathSegments<'_>,
389 ) -> (Ty, Option<TypeNs>) {
390 match remaining_segments.len() {
393 // resolve unselected assoc types
394 let segment = remaining_segments.first().unwrap();
395 (self.select_associated_type(res, segment), None)
398 // FIXME report error (ambiguous associated type)
399 (TyKind::Error.intern(&Interner), None)
404 pub(crate) fn lower_partly_resolved_path(
407 resolved_segment: PathSegment<'_>,
408 remaining_segments: PathSegments<'_>,
410 ) -> (Ty, Option<TypeNs>) {
411 let ty = match resolution {
412 TypeNs::TraitId(trait_) => {
413 let ty = if remaining_segments.len() == 1 {
415 self.lower_trait_ref_from_resolved_path(trait_, resolved_segment, None);
416 let segment = remaining_segments.first().unwrap();
419 .trait_data(trait_ref.hir_trait_id())
420 .associated_type_by_name(segment.name);
422 Some(associated_ty) => {
423 // FIXME handle type parameters on the segment
424 TyKind::Alias(AliasTy::Projection(ProjectionTy {
425 associated_ty_id: to_assoc_type_id(associated_ty),
426 substitution: trait_ref.substitution,
431 // FIXME: report error (associated type not found)
432 TyKind::Error.intern(&Interner)
435 } else if remaining_segments.len() > 1 {
436 // FIXME report error (ambiguous associated type)
437 TyKind::Error.intern(&Interner)
440 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0))
443 let trait_ref = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
444 ctx.lower_trait_ref_from_resolved_path(trait_, resolved_segment, self_ty)
447 bounds: crate::make_only_type_binders(
449 QuantifiedWhereClauses::from_iter(
451 Some(crate::wrap_empty_binders(WhereClause::Implemented(
456 lifetime: static_lifetime(),
458 TyKind::Dyn(dyn_ty).intern(&Interner)
462 TypeNs::GenericParam(param_id) => {
463 let generics = generics(
465 self.resolver.generic_def().expect("generics in scope"),
467 match self.type_param_mode {
468 TypeParamLoweringMode::Placeholder => {
469 TyKind::Placeholder(to_placeholder_idx(self.db, param_id))
471 TypeParamLoweringMode::Variable => {
472 let idx = generics.param_idx(param_id).expect("matching generics");
473 TyKind::BoundVar(BoundVar::new(self.in_binders, idx))
478 TypeNs::SelfType(impl_id) => {
479 let generics = generics(self.db.upcast(), impl_id.into());
480 let substs = match self.type_param_mode {
481 TypeParamLoweringMode::Placeholder => generics.type_params_subst(self.db),
482 TypeParamLoweringMode::Variable => generics.bound_vars_subst(self.in_binders),
484 self.db.impl_self_ty(impl_id).substitute(&Interner, &substs)
486 TypeNs::AdtSelfType(adt) => {
487 let generics = generics(self.db.upcast(), adt.into());
488 let substs = match self.type_param_mode {
489 TypeParamLoweringMode::Placeholder => generics.type_params_subst(self.db),
490 TypeParamLoweringMode::Variable => generics.bound_vars_subst(self.in_binders),
492 self.db.ty(adt.into()).substitute(&Interner, &substs)
495 TypeNs::AdtId(it) => self.lower_path_inner(resolved_segment, it.into(), infer_args),
496 TypeNs::BuiltinType(it) => {
497 self.lower_path_inner(resolved_segment, it.into(), infer_args)
499 TypeNs::TypeAliasId(it) => {
500 self.lower_path_inner(resolved_segment, it.into(), infer_args)
502 // FIXME: report error
503 TypeNs::EnumVariantId(_) => return (TyKind::Error.intern(&Interner), None),
505 self.lower_ty_relative_path(ty, Some(resolution), remaining_segments)
508 pub(crate) fn lower_path(&self, path: &Path) -> (Ty, Option<TypeNs>) {
509 // Resolve the path (in type namespace)
510 if let Some(type_ref) = path.type_anchor() {
511 let (ty, res) = self.lower_ty_ext(type_ref);
512 return self.lower_ty_relative_path(ty, res, path.segments());
514 let (resolution, remaining_index) =
515 match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
517 None => return (TyKind::Error.intern(&Interner), None),
519 let (resolved_segment, remaining_segments) = match remaining_index {
521 path.segments().last().expect("resolved path has at least one element"),
524 Some(i) => (path.segments().get(i - 1).unwrap(), path.segments().skip(i)),
526 self.lower_partly_resolved_path(resolution, resolved_segment, remaining_segments, false)
529 fn select_associated_type(&self, res: Option<TypeNs>, segment: PathSegment<'_>) -> Ty {
530 if let Some(res) = res {
531 let ty = associated_type_shorthand_candidates(
534 move |name, t, associated_ty| {
535 if name == segment.name {
536 let substs = match self.type_param_mode {
537 TypeParamLoweringMode::Placeholder => {
538 // if we're lowering to placeholders, we have to put
540 let generics = generics(
542 self.resolver.generic_def().expect(
543 "there should be generics if there's a generic param",
546 let s = generics.type_params_subst(self.db);
547 s.apply(t.substitution.clone(), &Interner)
549 TypeParamLoweringMode::Variable => t.substitution.clone(),
551 // We need to shift in the bound vars, since
552 // associated_type_shorthand_candidates does not do that
553 let substs = substs.shifted_in_from(&Interner, self.in_binders);
554 // FIXME handle type parameters on the segment
556 TyKind::Alias(AliasTy::Projection(ProjectionTy {
557 associated_ty_id: to_assoc_type_id(associated_ty),
558 substitution: substs,
568 ty.unwrap_or_else(|| TyKind::Error.intern(&Interner))
570 TyKind::Error.intern(&Interner)
576 segment: PathSegment<'_>,
580 let generic_def = match typeable {
581 TyDefId::BuiltinType(_) => None,
582 TyDefId::AdtId(it) => Some(it.into()),
583 TyDefId::TypeAliasId(it) => Some(it.into()),
585 let substs = self.substs_from_path_segment(segment, generic_def, infer_args, None);
586 self.db.ty(typeable).substitute(&Interner, &substs)
589 /// Collect generic arguments from a path into a `Substs`. See also
590 /// `create_substs_for_ast_path` and `def_to_ty` in rustc.
591 pub(super) fn substs_from_path(
594 // Note that we don't call `db.value_type(resolved)` here,
595 // `ValueTyDefId` is just a convenient way to pass generics and
596 // special-case enum variants
597 resolved: ValueTyDefId,
600 let last = path.segments().last().expect("path should have at least one segment");
601 let (segment, generic_def) = match resolved {
602 ValueTyDefId::FunctionId(it) => (last, Some(it.into())),
603 ValueTyDefId::StructId(it) => (last, Some(it.into())),
604 ValueTyDefId::UnionId(it) => (last, Some(it.into())),
605 ValueTyDefId::ConstId(it) => (last, Some(it.into())),
606 ValueTyDefId::StaticId(_) => (last, None),
607 ValueTyDefId::EnumVariantId(var) => {
608 // the generic args for an enum variant may be either specified
609 // on the segment referring to the enum, or on the segment
610 // referring to the variant. So `Option::<T>::None` and
611 // `Option::None::<T>` are both allowed (though the former is
612 // preferred). See also `def_ids_for_path_segments` in rustc.
613 let len = path.segments().len();
614 let penultimate = if len >= 2 { path.segments().get(len - 2) } else { None };
615 let segment = match penultimate {
616 Some(segment) if segment.args_and_bindings.is_some() => segment,
619 (segment, Some(var.parent.into()))
622 self.substs_from_path_segment(segment, generic_def, infer_args, None)
625 fn substs_from_path_segment(
627 segment: PathSegment<'_>,
628 def_generic: Option<GenericDefId>,
630 explicit_self_ty: Option<Ty>,
632 let mut substs = Vec::new();
633 let def_generics = def_generic.map(|def| generics(self.db.upcast(), def));
635 let (parent_params, self_params, type_params, impl_trait_params) =
636 def_generics.map_or((0, 0, 0, 0), |g| g.provenance_split());
637 let total_len = parent_params + self_params + type_params + impl_trait_params;
639 substs.extend(iter::repeat(TyKind::Error.intern(&Interner)).take(parent_params));
641 let fill_self_params = || {
645 .chain(iter::repeat(TyKind::Error.intern(&Interner)))
649 let mut had_explicit_type_args = false;
651 if let Some(generic_args) = &segment.args_and_bindings {
652 if !generic_args.has_self_type {
656 if generic_args.has_self_type { self_params + type_params } else { type_params };
657 let skip = if generic_args.has_self_type && self_params == 0 { 1 } else { 0 };
658 // if args are provided, it should be all of them, but we can't rely on that
659 for arg in generic_args
662 .filter(|arg| matches!(arg, GenericArg::Type(_)))
667 GenericArg::Type(type_ref) => {
668 had_explicit_type_args = true;
669 let ty = self.lower_ty(type_ref);
672 GenericArg::Lifetime(_) => {}
679 // handle defaults. In expression or pattern path segments without
680 // explicitly specified type arguments, missing type arguments are inferred
681 // (i.e. defaults aren't used).
682 if !infer_args || had_explicit_type_args {
683 if let Some(def_generic) = def_generic {
684 let defaults = self.db.generic_defaults(def_generic);
685 assert_eq!(total_len, defaults.len());
687 for default_ty in defaults.iter().skip(substs.len()) {
688 // each default can depend on the previous parameters
689 let substs_so_far = Substitution::from_iter(&Interner, substs.clone());
690 substs.push(default_ty.clone().substitute(&Interner, &substs_so_far));
695 // add placeholders for args that were not provided
696 // FIXME: emit diagnostics in contexts where this is not allowed
697 for _ in substs.len()..total_len {
698 substs.push(TyKind::Error.intern(&Interner));
700 assert_eq!(substs.len(), total_len);
702 Substitution::from_iter(&Interner, substs)
705 fn lower_trait_ref_from_path(
708 explicit_self_ty: Option<Ty>,
709 ) -> Option<TraitRef> {
711 match self.resolver.resolve_path_in_type_ns_fully(self.db.upcast(), path.mod_path())? {
712 TypeNs::TraitId(tr) => tr,
715 let segment = path.segments().last().expect("path should have at least one segment");
716 Some(self.lower_trait_ref_from_resolved_path(resolved, segment, explicit_self_ty))
719 pub(crate) fn lower_trait_ref_from_resolved_path(
722 segment: PathSegment<'_>,
723 explicit_self_ty: Option<Ty>,
725 let substs = self.trait_ref_substs_from_path(segment, resolved, explicit_self_ty);
726 TraitRef { trait_id: to_chalk_trait_id(resolved), substitution: substs }
731 trait_ref: &HirTraitRef,
732 explicit_self_ty: Option<Ty>,
733 ) -> Option<TraitRef> {
734 self.lower_trait_ref_from_path(&trait_ref.path, explicit_self_ty)
737 fn trait_ref_substs_from_path(
739 segment: PathSegment<'_>,
741 explicit_self_ty: Option<Ty>,
743 self.substs_from_path_segment(segment, Some(resolved.into()), false, explicit_self_ty)
746 pub(crate) fn lower_where_predicate(
748 where_predicate: &'a WherePredicate,
749 ignore_bindings: bool,
750 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
751 match where_predicate {
752 WherePredicate::ForLifetime { target, bound, .. }
753 | WherePredicate::TypeBound { target, bound } => {
754 let self_ty = match target {
755 WherePredicateTypeTarget::TypeRef(type_ref) => self.lower_ty(type_ref),
756 WherePredicateTypeTarget::TypeParam(param_id) => {
757 let generic_def = self.resolver.generic_def().expect("generics in scope");
758 let generics = generics(self.db.upcast(), generic_def);
760 hir_def::TypeParamId { parent: generic_def, local_id: *param_id };
761 let placeholder = to_placeholder_idx(self.db, param_id);
762 match self.type_param_mode {
763 TypeParamLoweringMode::Placeholder => TyKind::Placeholder(placeholder),
764 TypeParamLoweringMode::Variable => {
765 let idx = generics.param_idx(param_id).expect("matching generics");
766 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, idx))
772 self.lower_type_bound(bound, self_ty, ignore_bindings)
776 WherePredicate::Lifetime { .. } => vec![].into_iter(),
780 pub(crate) fn lower_type_bound(
782 bound: &'a TypeBound,
784 ignore_bindings: bool,
785 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
786 let mut bindings = None;
787 let trait_ref = match bound {
788 TypeBound::Path(path, TraitBoundModifier::None) => {
789 bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
790 bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
792 TypeBound::Path(path, TraitBoundModifier::Maybe) => {
793 let sized_trait = self
796 .and_then(|krate| self.db.lang_item(krate, "sized".into()))
797 .and_then(|lang_item| lang_item.as_trait());
798 // Don't lower associated type bindings as the only possible relaxed trait bound
799 // `?Sized` has no of them.
800 // If we got another trait here ignore the bound completely.
802 .lower_trait_ref_from_path(path, Some(self_ty.clone()))
803 .map(|trait_ref| trait_ref.hir_trait_id());
804 if trait_id == sized_trait {
805 self.unsized_types.borrow_mut().insert(self_ty);
809 TypeBound::ForLifetime(_, path) => {
810 // FIXME Don't silently drop the hrtb lifetimes here
811 bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
812 bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
814 TypeBound::Lifetime(_) => None,
815 TypeBound::Error => None,
817 trait_ref.into_iter().chain(
820 .filter(move |_| !ignore_bindings)
821 .flat_map(move |tr| self.assoc_type_bindings_from_type_bound(bound, tr)),
825 fn assoc_type_bindings_from_type_bound(
827 bound: &'a TypeBound,
829 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
830 let last_segment = match bound {
831 TypeBound::Path(path, TraitBoundModifier::None) | TypeBound::ForLifetime(_, path) => {
832 path.segments().last()
834 TypeBound::Path(_, TraitBoundModifier::Maybe)
836 | TypeBound::Lifetime(_) => None,
840 .flat_map(|segment| segment.args_and_bindings.into_iter())
841 .flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
842 .flat_map(move |binding| {
843 let found = associated_type_by_name_including_super_traits(
848 let (super_trait_ref, associated_ty) = match found {
849 None => return SmallVec::<[QuantifiedWhereClause; 1]>::new(),
852 let projection_ty = ProjectionTy {
853 associated_ty_id: to_assoc_type_id(associated_ty),
854 substitution: super_trait_ref.substitution,
856 let mut preds = SmallVec::with_capacity(
857 binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
859 if let Some(type_ref) = &binding.type_ref {
860 let ty = self.lower_ty(type_ref);
862 AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty };
863 preds.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq)));
865 for bound in &binding.bounds {
866 preds.extend(self.lower_type_bound(
868 TyKind::Alias(AliasTy::Projection(projection_ty.clone())).intern(&Interner),
878 bounds: &[Interned<TypeBound>],
880 ) -> ReturnTypeImplTrait {
881 cov_mark::hit!(lower_rpit);
883 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(&Interner);
884 let predicates = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
885 let mut predicates: Vec<_> = bounds
887 .flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false))
890 if !ctx.unsized_types.borrow().contains(&self_ty) {
891 let krate = func.lookup(ctx.db.upcast()).module(ctx.db.upcast()).krate();
892 let sized_trait = ctx
894 .lang_item(krate, "sized".into())
895 .and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id));
896 let sized_clause = sized_trait.map(|trait_id| {
897 let clause = WhereClause::Implemented(TraitRef {
899 substitution: Substitution::from1(&Interner, self_ty.clone()),
901 crate::wrap_empty_binders(clause)
903 predicates.extend(sized_clause.into_iter());
904 predicates.shrink_to_fit();
909 ReturnTypeImplTrait { bounds: crate::make_only_type_binders(1, predicates) }
913 fn count_impl_traits(type_ref: &TypeRef) -> usize {
915 type_ref.walk(&mut |type_ref| {
916 if matches!(type_ref, TypeRef::ImplTrait(_)) {
923 /// Build the signature of a callable item (function, struct or enum variant).
924 pub fn callable_item_sig(db: &dyn HirDatabase, def: CallableDefId) -> PolyFnSig {
926 CallableDefId::FunctionId(f) => fn_sig_for_fn(db, f),
927 CallableDefId::StructId(s) => fn_sig_for_struct_constructor(db, s),
928 CallableDefId::EnumVariantId(e) => fn_sig_for_enum_variant_constructor(db, e),
932 pub fn associated_type_shorthand_candidates<R>(
933 db: &dyn HirDatabase,
935 mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>,
937 let mut search = |t| {
938 for t in all_super_trait_refs(db, t) {
939 let data = db.trait_data(t.hir_trait_id());
941 for (name, assoc_id) in &data.items {
942 if let AssocItemId::TypeAliasId(alias) = assoc_id {
943 if let Some(result) = cb(name, &t, *alias) {
953 TypeNs::SelfType(impl_id) => search(
954 // we're _in_ the impl -- the binders get added back later. Correct,
955 // but it would be nice to make this more explicit
956 db.impl_trait(impl_id)?.into_value_and_skipped_binders().0,
958 TypeNs::GenericParam(param_id) => {
959 let predicates = db.generic_predicates_for_param(param_id);
960 let res = predicates.iter().find_map(|pred| match pred.skip_binders().skip_binders() {
961 // FIXME: how to correctly handle higher-ranked bounds here?
962 WhereClause::Implemented(tr) => search(
964 .shifted_out_to(&Interner, DebruijnIndex::ONE)
965 .expect("FIXME unexpected higher-ranked trait bound"),
969 if let res @ Some(_) = res {
972 // Handle `Self::Type` referring to own associated type in trait definitions
973 if let GenericDefId::TraitId(trait_id) = param_id.parent {
974 let generics = generics(db.upcast(), trait_id.into());
975 if generics.params.types[param_id.local_id].provenance
976 == TypeParamProvenance::TraitSelf
978 let trait_ref = TyBuilder::trait_ref(db, trait_id)
979 .fill_with_bound_vars(DebruijnIndex::INNERMOST, 0)
981 return search(trait_ref);
990 /// Build the type of all specific fields of a struct or enum variant.
991 pub(crate) fn field_types_query(
992 db: &dyn HirDatabase,
993 variant_id: VariantId,
994 ) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>> {
995 let var_data = variant_id.variant_data(db.upcast());
996 let (resolver, def): (_, GenericDefId) = match variant_id {
997 VariantId::StructId(it) => (it.resolver(db.upcast()), it.into()),
998 VariantId::UnionId(it) => (it.resolver(db.upcast()), it.into()),
999 VariantId::EnumVariantId(it) => (it.parent.resolver(db.upcast()), it.parent.into()),
1001 let generics = generics(db.upcast(), def);
1002 let mut res = ArenaMap::default();
1004 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1005 for (field_id, field_data) in var_data.fields().iter() {
1006 res.insert(field_id, make_binders(&generics, ctx.lower_ty(&field_data.type_ref)))
1011 /// This query exists only to be used when resolving short-hand associated types
1014 /// See the analogous query in rustc and its comment:
1015 /// <https://github.com/rust-lang/rust/blob/9150f844e2624eb013ec78ca08c1d416e6644026/src/librustc_typeck/astconv.rs#L46>
1016 /// This is a query mostly to handle cycles somewhat gracefully; e.g. the
1017 /// following bounds are disallowed: `T: Foo<U::Item>, U: Foo<T::Item>`, but
1018 /// these are fine: `T: Foo<U::Item>, U: Foo<()>`.
1019 pub(crate) fn generic_predicates_for_param_query(
1020 db: &dyn HirDatabase,
1021 param_id: TypeParamId,
1022 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
1023 let resolver = param_id.parent.resolver(db.upcast());
1025 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1026 let generics = generics(db.upcast(), param_id.parent);
1027 let mut predicates: Vec<_> = resolver
1028 .where_predicates_in_scope()
1029 // we have to filter out all other predicates *first*, before attempting to lower them
1030 .filter(|pred| match pred {
1031 WherePredicate::ForLifetime { target, .. }
1032 | WherePredicate::TypeBound { target, .. } => match target {
1033 WherePredicateTypeTarget::TypeRef(type_ref) => {
1034 ctx.lower_ty_only_param(type_ref) == Some(param_id)
1036 WherePredicateTypeTarget::TypeParam(local_id) => *local_id == param_id.local_id,
1038 WherePredicate::Lifetime { .. } => false,
1040 .flat_map(|pred| ctx.lower_where_predicate(pred, true).map(|p| make_binders(&generics, p)))
1043 let subst = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1044 let explicitly_unsized_tys = ctx.unsized_types.into_inner();
1045 let implicitly_sized_predicates =
1046 implicitly_sized_clauses(db, param_id.parent, &explicitly_unsized_tys, &subst, &resolver)
1047 .map(|p| make_binders(&generics, crate::wrap_empty_binders(p)));
1048 predicates.extend(implicitly_sized_predicates);
1052 pub(crate) fn generic_predicates_for_param_recover(
1053 _db: &dyn HirDatabase,
1055 _param_id: &TypeParamId,
1056 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
1060 pub(crate) fn trait_environment_query(
1061 db: &dyn HirDatabase,
1063 ) -> Arc<TraitEnvironment> {
1064 let resolver = def.resolver(db.upcast());
1065 let ctx = TyLoweringContext::new(db, &resolver)
1066 .with_type_param_mode(TypeParamLoweringMode::Placeholder);
1067 let mut traits_in_scope = Vec::new();
1068 let mut clauses = Vec::new();
1069 for pred in resolver.where_predicates_in_scope() {
1070 for pred in ctx.lower_where_predicate(pred, false) {
1071 if let WhereClause::Implemented(tr) = &pred.skip_binders() {
1073 .push((tr.self_type_parameter(&Interner).clone(), tr.hir_trait_id()));
1075 let program_clause: chalk_ir::ProgramClause<Interner> = pred.cast(&Interner);
1076 clauses.push(program_clause.into_from_env_clause(&Interner));
1080 let container: Option<AssocContainerId> = match def {
1081 // FIXME: is there a function for this?
1082 GenericDefId::FunctionId(f) => Some(f.lookup(db.upcast()).container),
1083 GenericDefId::AdtId(_) => None,
1084 GenericDefId::TraitId(_) => None,
1085 GenericDefId::TypeAliasId(t) => Some(t.lookup(db.upcast()).container),
1086 GenericDefId::ImplId(_) => None,
1087 GenericDefId::EnumVariantId(_) => None,
1088 GenericDefId::ConstId(c) => Some(c.lookup(db.upcast()).container),
1090 if let Some(AssocContainerId::TraitId(trait_id)) = container {
1091 // add `Self: Trait<T1, T2, ...>` to the environment in trait
1092 // function default implementations (and speculative code
1093 // inside consts or type aliases)
1094 cov_mark::hit!(trait_self_implements_self);
1095 let substs = TyBuilder::type_params_subst(db, trait_id);
1096 let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs };
1097 let pred = WhereClause::Implemented(trait_ref);
1098 let program_clause: chalk_ir::ProgramClause<Interner> = pred.cast(&Interner);
1099 clauses.push(program_clause.into_from_env_clause(&Interner));
1102 let subst = generics(db.upcast(), def).type_params_subst(db);
1103 let explicitly_unsized_tys = ctx.unsized_types.into_inner();
1104 let implicitly_sized_clauses =
1105 implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver).map(|pred| {
1106 let program_clause: chalk_ir::ProgramClause<Interner> = pred.cast(&Interner);
1107 program_clause.into_from_env_clause(&Interner)
1109 clauses.extend(implicitly_sized_clauses);
1111 let krate = def.module(db.upcast()).krate();
1113 let env = chalk_ir::Environment::new(&Interner).add_clauses(&Interner, clauses);
1115 Arc::new(TraitEnvironment { krate, traits_from_clauses: traits_in_scope, env })
1118 /// Resolve the where clause(s) of an item with generics.
1119 pub(crate) fn generic_predicates_query(
1120 db: &dyn HirDatabase,
1122 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
1123 let resolver = def.resolver(db.upcast());
1125 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1126 let generics = generics(db.upcast(), def);
1128 let mut predicates = resolver
1129 .where_predicates_in_scope()
1130 .flat_map(|pred| ctx.lower_where_predicate(pred, false).map(|p| make_binders(&generics, p)))
1131 .collect::<Vec<_>>();
1133 let subst = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1134 let explicitly_unsized_tys = ctx.unsized_types.into_inner();
1135 let implicitly_sized_predicates =
1136 implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver)
1137 .map(|p| make_binders(&generics, crate::wrap_empty_binders(p)));
1138 predicates.extend(implicitly_sized_predicates);
1142 /// Generate implicit `: Sized` predicates for all generics that has no `?Sized` bound.
1143 /// Exception is Self of a trait def.
1144 fn implicitly_sized_clauses<'a>(
1145 db: &dyn HirDatabase,
1147 explicitly_unsized_tys: &'a FxHashSet<Ty>,
1148 substitution: &'a Substitution,
1149 resolver: &Resolver,
1150 ) -> impl Iterator<Item = WhereClause> + 'a {
1151 let is_trait_def = matches!(def, GenericDefId::TraitId(..));
1152 let generic_args = &substitution.as_slice(&Interner)[is_trait_def as usize..];
1153 let sized_trait = resolver
1155 .and_then(|krate| db.lang_item(krate, "sized".into()))
1156 .and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id));
1158 sized_trait.into_iter().flat_map(move |sized_trait| {
1159 let implicitly_sized_tys = generic_args
1161 .filter_map(|generic_arg| generic_arg.ty(&Interner))
1162 .filter(move |&self_ty| !explicitly_unsized_tys.contains(self_ty));
1163 implicitly_sized_tys.map(move |self_ty| {
1164 WhereClause::Implemented(TraitRef {
1165 trait_id: sized_trait,
1166 substitution: Substitution::from1(&Interner, self_ty.clone()),
1172 /// Resolve the default type params from generics
1173 pub(crate) fn generic_defaults_query(
1174 db: &dyn HirDatabase,
1176 ) -> Arc<[Binders<Ty>]> {
1177 let resolver = def.resolver(db.upcast());
1179 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1180 let generic_params = generics(db.upcast(), def);
1182 let defaults = generic_params
1185 .map(|(idx, (_, p))| {
1187 p.default.as_ref().map_or(TyKind::Error.intern(&Interner), |t| ctx.lower_ty(t));
1189 // Each default can only refer to previous parameters.
1190 ty = crate::fold_free_vars(ty, |bound, binders| {
1191 if bound.index >= idx && bound.debruijn == DebruijnIndex::INNERMOST {
1192 // type variable default referring to parameter coming
1193 // after it. This is forbidden (FIXME: report
1195 TyKind::Error.intern(&Interner)
1197 bound.shifted_in_from(binders).to_ty(&Interner)
1201 crate::make_only_type_binders(idx, ty)
1208 pub(crate) fn generic_defaults_recover(
1209 db: &dyn HirDatabase,
1212 ) -> Arc<[Binders<Ty>]> {
1213 let generic_params = generics(db.upcast(), *def);
1215 // we still need one default per parameter
1216 let defaults = generic_params
1220 let ty = TyKind::Error.intern(&Interner);
1222 crate::make_only_type_binders(idx, ty)
1229 fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
1230 let data = db.function_data(def);
1231 let resolver = def.resolver(db.upcast());
1232 let ctx_params = TyLoweringContext::new(db, &resolver)
1233 .with_impl_trait_mode(ImplTraitLoweringMode::Variable)
1234 .with_type_param_mode(TypeParamLoweringMode::Variable);
1235 let params = data.params.iter().map(|tr| ctx_params.lower_ty(tr)).collect::<Vec<_>>();
1236 let ctx_ret = TyLoweringContext::new(db, &resolver)
1237 .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
1238 .with_type_param_mode(TypeParamLoweringMode::Variable);
1239 let ret = ctx_ret.lower_ty(&data.ret_type);
1240 let generics = generics(db.upcast(), def.into());
1241 make_binders(&generics, CallableSig::from_params_and_return(params, ret, data.is_varargs()))
1244 /// Build the declared type of a function. This should not need to look at the
1246 fn type_for_fn(db: &dyn HirDatabase, def: FunctionId) -> Binders<Ty> {
1247 let generics = generics(db.upcast(), def.into());
1248 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1251 TyKind::FnDef(CallableDefId::FunctionId(def).to_chalk(db), substs).intern(&Interner),
1255 /// Build the declared type of a const.
1256 fn type_for_const(db: &dyn HirDatabase, def: ConstId) -> Binders<Ty> {
1257 let data = db.const_data(def);
1258 let generics = generics(db.upcast(), def.into());
1259 let resolver = def.resolver(db.upcast());
1261 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1263 make_binders(&generics, ctx.lower_ty(&data.type_ref))
1266 /// Build the declared type of a static.
1267 fn type_for_static(db: &dyn HirDatabase, def: StaticId) -> Binders<Ty> {
1268 let data = db.static_data(def);
1269 let resolver = def.resolver(db.upcast());
1270 let ctx = TyLoweringContext::new(db, &resolver);
1272 Binders::empty(&Interner, ctx.lower_ty(&data.type_ref))
1275 fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnSig {
1276 let struct_data = db.struct_data(def);
1277 let fields = struct_data.variant_data.fields();
1278 let resolver = def.resolver(db.upcast());
1280 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1281 let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
1282 let (ret, binders) = type_for_adt(db, def.into()).into_value_and_skipped_binders();
1283 Binders::new(binders, CallableSig::from_params_and_return(params, ret, false))
1286 /// Build the type of a tuple struct constructor.
1287 fn type_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> Binders<Ty> {
1288 let struct_data = db.struct_data(def);
1289 if let StructKind::Unit = struct_data.variant_data.kind() {
1290 return type_for_adt(db, def.into());
1292 let generics = generics(db.upcast(), def.into());
1293 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1296 TyKind::FnDef(CallableDefId::StructId(def).to_chalk(db), substs).intern(&Interner),
1300 fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> PolyFnSig {
1301 let enum_data = db.enum_data(def.parent);
1302 let var_data = &enum_data.variants[def.local_id];
1303 let fields = var_data.variant_data.fields();
1304 let resolver = def.parent.resolver(db.upcast());
1306 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1307 let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
1308 let (ret, binders) = type_for_adt(db, def.parent.into()).into_value_and_skipped_binders();
1309 Binders::new(binders, CallableSig::from_params_and_return(params, ret, false))
1312 /// Build the type of a tuple enum variant constructor.
1313 fn type_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> Binders<Ty> {
1314 let enum_data = db.enum_data(def.parent);
1315 let var_data = &enum_data.variants[def.local_id].variant_data;
1316 if let StructKind::Unit = var_data.kind() {
1317 return type_for_adt(db, def.parent.into());
1319 let generics = generics(db.upcast(), def.parent.into());
1320 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1323 TyKind::FnDef(CallableDefId::EnumVariantId(def).to_chalk(db), substs).intern(&Interner),
1327 fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
1328 let generics = generics(db.upcast(), adt.into());
1329 let b = TyBuilder::adt(db, adt);
1330 let ty = b.fill_with_bound_vars(DebruijnIndex::INNERMOST, 0).build();
1331 make_binders(&generics, ty)
1334 fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
1335 let generics = generics(db.upcast(), t.into());
1336 let resolver = t.resolver(db.upcast());
1338 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1339 if db.type_alias_data(t).is_extern {
1340 Binders::empty(&Interner, TyKind::Foreign(crate::to_foreign_def_id(t)).intern(&Interner))
1342 let type_ref = &db.type_alias_data(t).type_ref;
1343 let inner = ctx.lower_ty(type_ref.as_deref().unwrap_or(&TypeRef::Error));
1344 make_binders(&generics, inner)
1348 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
1349 pub enum CallableDefId {
1350 FunctionId(FunctionId),
1352 EnumVariantId(EnumVariantId),
1354 impl_from!(FunctionId, StructId, EnumVariantId for CallableDefId);
1356 impl CallableDefId {
1357 pub fn krate(self, db: &dyn HirDatabase) -> CrateId {
1358 let db = db.upcast();
1360 CallableDefId::FunctionId(f) => f.lookup(db).module(db),
1361 CallableDefId::StructId(s) => s.lookup(db).container,
1362 CallableDefId::EnumVariantId(e) => e.parent.lookup(db).container,
1368 impl From<CallableDefId> for GenericDefId {
1369 fn from(def: CallableDefId) -> GenericDefId {
1371 CallableDefId::FunctionId(f) => f.into(),
1372 CallableDefId::StructId(s) => s.into(),
1373 CallableDefId::EnumVariantId(e) => e.into(),
1378 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1380 BuiltinType(BuiltinType),
1382 TypeAliasId(TypeAliasId),
1384 impl_from!(BuiltinType, AdtId(StructId, EnumId, UnionId), TypeAliasId for TyDefId);
1386 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1387 pub enum ValueTyDefId {
1388 FunctionId(FunctionId),
1391 EnumVariantId(EnumVariantId),
1395 impl_from!(FunctionId, StructId, UnionId, EnumVariantId, ConstId, StaticId for ValueTyDefId);
1397 /// Build the declared type of an item. This depends on the namespace; e.g. for
1398 /// `struct Foo(usize)`, we have two types: The type of the struct itself, and
1399 /// the constructor function `(usize) -> Foo` which lives in the values
1401 pub(crate) fn ty_query(db: &dyn HirDatabase, def: TyDefId) -> Binders<Ty> {
1403 TyDefId::BuiltinType(it) => Binders::empty(&Interner, TyBuilder::builtin(it)),
1404 TyDefId::AdtId(it) => type_for_adt(db, it),
1405 TyDefId::TypeAliasId(it) => type_for_type_alias(db, it),
1409 pub(crate) fn ty_recover(db: &dyn HirDatabase, _cycle: &[String], def: &TyDefId) -> Binders<Ty> {
1410 let generics = match *def {
1411 TyDefId::BuiltinType(_) => {
1412 return Binders::empty(&Interner, TyKind::Error.intern(&Interner))
1414 TyDefId::AdtId(it) => generics(db.upcast(), it.into()),
1415 TyDefId::TypeAliasId(it) => generics(db.upcast(), it.into()),
1417 make_binders(&generics, TyKind::Error.intern(&Interner))
1420 pub(crate) fn value_ty_query(db: &dyn HirDatabase, def: ValueTyDefId) -> Binders<Ty> {
1422 ValueTyDefId::FunctionId(it) => type_for_fn(db, it),
1423 ValueTyDefId::StructId(it) => type_for_struct_constructor(db, it),
1424 ValueTyDefId::UnionId(it) => type_for_adt(db, it.into()),
1425 ValueTyDefId::EnumVariantId(it) => type_for_enum_variant_constructor(db, it),
1426 ValueTyDefId::ConstId(it) => type_for_const(db, it),
1427 ValueTyDefId::StaticId(it) => type_for_static(db, it),
1431 pub(crate) fn impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binders<Ty> {
1432 let impl_loc = impl_id.lookup(db.upcast());
1433 let impl_data = db.impl_data(impl_id);
1434 let resolver = impl_id.resolver(db.upcast());
1435 let _cx = stdx::panic_context::enter(format!(
1436 "impl_self_ty_query({:?} -> {:?} -> {:?})",
1437 impl_id, impl_loc, impl_data
1439 let generics = generics(db.upcast(), impl_id.into());
1441 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1442 make_binders(&generics, ctx.lower_ty(&impl_data.self_ty))
1445 pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
1446 let parent_data = db.generic_params(def.parent);
1447 let data = &parent_data.consts[def.local_id];
1448 let resolver = def.parent.resolver(db.upcast());
1449 let ctx = TyLoweringContext::new(db, &resolver);
1451 ctx.lower_ty(&data.ty)
1454 pub(crate) fn impl_self_ty_recover(
1455 db: &dyn HirDatabase,
1459 let generics = generics(db.upcast(), (*impl_id).into());
1460 make_binders(&generics, TyKind::Error.intern(&Interner))
1463 pub(crate) fn impl_trait_query(db: &dyn HirDatabase, impl_id: ImplId) -> Option<Binders<TraitRef>> {
1464 let impl_loc = impl_id.lookup(db.upcast());
1465 let impl_data = db.impl_data(impl_id);
1466 let resolver = impl_id.resolver(db.upcast());
1467 let _cx = stdx::panic_context::enter(format!(
1468 "impl_trait_query({:?} -> {:?} -> {:?})",
1469 impl_id, impl_loc, impl_data
1472 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1473 let (self_ty, binders) = db.impl_self_ty(impl_id).into_value_and_skipped_binders();
1474 let target_trait = impl_data.target_trait.as_ref()?;
1475 Some(Binders::new(binders, ctx.lower_trait_ref(target_trait, Some(self_ty))?))
1478 pub(crate) fn return_type_impl_traits(
1479 db: &dyn HirDatabase,
1480 def: hir_def::FunctionId,
1481 ) -> Option<Arc<Binders<ReturnTypeImplTraits>>> {
1482 // FIXME unify with fn_sig_for_fn instead of doing lowering twice, maybe
1483 let data = db.function_data(def);
1484 let resolver = def.resolver(db.upcast());
1485 let ctx_ret = TyLoweringContext::new(db, &resolver)
1486 .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
1487 .with_type_param_mode(TypeParamLoweringMode::Variable);
1488 let _ret = (&ctx_ret).lower_ty(&data.ret_type);
1489 let generics = generics(db.upcast(), def.into());
1490 let return_type_impl_traits =
1491 ReturnTypeImplTraits { impl_traits: ctx_ret.opaque_type_data.into_inner() };
1492 if return_type_impl_traits.impl_traits.is_empty() {
1495 Some(Arc::new(make_binders(&generics, return_type_impl_traits)))
1499 pub(crate) fn lower_to_chalk_mutability(m: hir_def::type_ref::Mutability) -> Mutability {
1501 hir_def::type_ref::Mutability::Shared => Mutability::Not,
1502 hir_def::type_ref::Mutability::Mut => Mutability::Mut,
1506 fn make_binders<T: HasInterner<Interner = Interner>>(generics: &Generics, value: T) -> Binders<T> {
1507 crate::make_only_type_binders(generics.len(), value)