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::{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 smallvec::SmallVec;
36 static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx,
38 all_super_trait_refs, associated_type_by_name_including_super_traits, generics, Generics,
40 AliasEq, AliasTy, Binders, BoundVar, CallableSig, DebruijnIndex, DynTy, FnPointer, FnSig,
41 FnSubst, ImplTraitId, Interner, PolyFnSig, ProjectionTy, QuantifiedWhereClause,
42 QuantifiedWhereClauses, ReturnTypeImplTrait, ReturnTypeImplTraits, Substitution,
43 TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyKind, WhereClause,
47 pub struct TyLoweringContext<'a> {
48 pub db: &'a dyn HirDatabase,
49 pub resolver: &'a Resolver,
50 in_binders: DebruijnIndex,
51 /// Note: Conceptually, it's thinkable that we could be in a location where
52 /// some type params should be represented as placeholders, and others
53 /// should be converted to variables. I think in practice, this isn't
54 /// possible currently, so this should be fine for now.
55 pub type_param_mode: TypeParamLoweringMode,
56 pub impl_trait_mode: ImplTraitLoweringMode,
57 impl_trait_counter: Cell<u16>,
58 /// When turning `impl Trait` into opaque types, we have to collect the
59 /// bounds at the same time to get the IDs correct (without becoming too
60 /// complicated). I don't like using interior mutability (as for the
61 /// counter), but I've tried and failed to make the lifetimes work for
62 /// passing around a `&mut TyLoweringContext`. The core problem is that
63 /// we're grouping the mutable data (the counter and this field) together
64 /// with the immutable context (the references to the DB and resolver).
65 /// Splitting this up would be a possible fix.
66 opaque_type_data: RefCell<Vec<ReturnTypeImplTrait>>,
67 expander: RefCell<Option<Expander>>,
70 impl<'a> TyLoweringContext<'a> {
71 pub fn new(db: &'a dyn HirDatabase, resolver: &'a Resolver) -> Self {
72 let impl_trait_counter = Cell::new(0);
73 let impl_trait_mode = ImplTraitLoweringMode::Disallowed;
74 let type_param_mode = TypeParamLoweringMode::Placeholder;
75 let in_binders = DebruijnIndex::INNERMOST;
76 let opaque_type_data = RefCell::new(Vec::new());
85 expander: RefCell::new(None),
89 pub fn with_debruijn<T>(
91 debruijn: DebruijnIndex,
92 f: impl FnOnce(&TyLoweringContext) -> T,
94 let opaque_ty_data_vec = self.opaque_type_data.replace(Vec::new());
95 let expander = self.expander.replace(None);
98 impl_trait_counter: Cell::new(self.impl_trait_counter.get()),
99 opaque_type_data: RefCell::new(opaque_ty_data_vec),
100 expander: RefCell::new(expander),
103 let result = f(&new_ctx);
104 self.impl_trait_counter.set(new_ctx.impl_trait_counter.get());
105 self.opaque_type_data.replace(new_ctx.opaque_type_data.into_inner());
106 self.expander.replace(new_ctx.expander.into_inner());
110 pub fn with_shifted_in<T>(
112 debruijn: DebruijnIndex,
113 f: impl FnOnce(&TyLoweringContext) -> T,
115 self.with_debruijn(self.in_binders.shifted_in_from(debruijn), f)
118 pub fn with_impl_trait_mode(self, impl_trait_mode: ImplTraitLoweringMode) -> Self {
119 Self { impl_trait_mode, ..self }
122 pub fn with_type_param_mode(self, type_param_mode: TypeParamLoweringMode) -> Self {
123 Self { type_param_mode, ..self }
127 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
128 pub enum ImplTraitLoweringMode {
129 /// `impl Trait` gets lowered into an opaque type that doesn't unify with
130 /// anything except itself. This is used in places where values flow 'out',
131 /// i.e. for arguments of the function we're currently checking, and return
132 /// types of functions we're calling.
134 /// `impl Trait` gets lowered into a type variable. Used for argument
135 /// position impl Trait when inside the respective function, since it allows
136 /// us to support that without Chalk.
138 /// `impl Trait` gets lowered into a variable that can unify with some
139 /// type. This is used in places where values flow 'in', i.e. for arguments
140 /// of functions we're calling, and the return type of the function we're
141 /// currently checking.
143 /// `impl Trait` is disallowed and will be an error.
147 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
148 pub enum TypeParamLoweringMode {
153 impl<'a> TyLoweringContext<'a> {
154 pub fn lower_ty(&self, type_ref: &TypeRef) -> Ty {
155 self.lower_ty_ext(type_ref).0
158 pub fn lower_ty_ext(&self, type_ref: &TypeRef) -> (Ty, Option<TypeNs>) {
160 let ty = match type_ref {
161 TypeRef::Never => TyKind::Never.intern(&Interner),
162 TypeRef::Tuple(inner) => {
163 let inner_tys = inner.iter().map(|tr| self.lower_ty(tr));
164 TyKind::Tuple(inner_tys.len(), Substitution::from_iter(&Interner, inner_tys))
167 TypeRef::Path(path) => {
168 let (ty, res_) = self.lower_path(path);
172 TypeRef::RawPtr(inner, mutability) => {
173 let inner_ty = self.lower_ty(inner);
174 TyKind::Raw(lower_to_chalk_mutability(*mutability), inner_ty).intern(&Interner)
176 TypeRef::Array(inner, len) => {
177 let inner_ty = self.lower_ty(inner);
179 let const_len = consteval::usize_const(len.as_usize());
181 TyKind::Array(inner_ty, const_len).intern(&Interner)
183 TypeRef::Slice(inner) => {
184 let inner_ty = self.lower_ty(inner);
185 TyKind::Slice(inner_ty).intern(&Interner)
187 TypeRef::Reference(inner, _, mutability) => {
188 let inner_ty = self.lower_ty(inner);
189 let lifetime = static_lifetime();
190 TyKind::Ref(lower_to_chalk_mutability(*mutability), lifetime, inner_ty)
193 TypeRef::Placeholder => TyKind::Error.intern(&Interner),
194 TypeRef::Fn(params, is_varargs) => {
195 let substs = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
196 Substitution::from_iter(&Interner, params.iter().map(|tr| ctx.lower_ty(tr)))
198 TyKind::Function(FnPointer {
199 num_binders: 0, // FIXME lower `for<'a> fn()` correctly
200 sig: FnSig { abi: (), safety: Safety::Safe, variadic: *is_varargs },
201 substitution: FnSubst(substs),
205 TypeRef::DynTrait(bounds) => {
207 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(&Interner);
208 let bounds = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
209 QuantifiedWhereClauses::from_iter(
211 bounds.iter().flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false)),
214 let bounds = crate::make_only_type_binders(1, bounds);
215 TyKind::Dyn(DynTy { bounds, lifetime: static_lifetime() }).intern(&Interner)
217 TypeRef::ImplTrait(bounds) => {
218 match self.impl_trait_mode {
219 ImplTraitLoweringMode::Opaque => {
220 let idx = self.impl_trait_counter.get();
221 self.impl_trait_counter.set(idx + 1);
223 assert!(idx as usize == self.opaque_type_data.borrow().len());
224 // this dance is to make sure the data is in the right
225 // place even if we encounter more opaque types while
226 // lowering the bounds
227 self.opaque_type_data.borrow_mut().push(ReturnTypeImplTrait {
228 bounds: crate::make_only_type_binders(1, Vec::new()),
230 // We don't want to lower the bounds inside the binders
231 // we're currently in, because they don't end up inside
232 // those binders. E.g. when we have `impl Trait<impl
233 // OtherTrait<T>>`, the `impl OtherTrait<T>` can't refer
234 // to the self parameter from `impl Trait`, and the
235 // bounds aren't actually stored nested within each
236 // other, but separately. So if the `T` refers to a type
237 // parameter of the outer function, it's just one binder
238 // away instead of two.
239 let actual_opaque_type_data = self
240 .with_debruijn(DebruijnIndex::INNERMOST, |ctx| {
241 ctx.lower_impl_trait(bounds)
243 self.opaque_type_data.borrow_mut()[idx as usize] = actual_opaque_type_data;
245 let func = match self.resolver.generic_def() {
246 Some(GenericDefId::FunctionId(f)) => f,
247 _ => panic!("opaque impl trait lowering in non-function"),
249 let impl_trait_id = ImplTraitId::ReturnTypeImplTrait(func, idx);
250 let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into();
251 let generics = generics(self.db.upcast(), func.into());
252 let parameters = generics.bound_vars_subst(self.in_binders);
253 TyKind::OpaqueType(opaque_ty_id, parameters).intern(&Interner)
255 ImplTraitLoweringMode::Param => {
256 let idx = self.impl_trait_counter.get();
257 // FIXME we're probably doing something wrong here
258 self.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
259 if let Some(def) = self.resolver.generic_def() {
260 let generics = generics(self.db.upcast(), def);
263 .filter(|(_, data)| {
264 data.provenance == TypeParamProvenance::ArgumentImplTrait
267 .map_or(TyKind::Error, |(id, _)| {
268 TyKind::Placeholder(to_placeholder_idx(self.db, id))
270 param.intern(&Interner)
272 TyKind::Error.intern(&Interner)
275 ImplTraitLoweringMode::Variable => {
276 let idx = self.impl_trait_counter.get();
277 // FIXME we're probably doing something wrong here
278 self.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
279 let (parent_params, self_params, list_params, _impl_trait_params) =
280 if let Some(def) = self.resolver.generic_def() {
281 let generics = generics(self.db.upcast(), def);
282 generics.provenance_split()
286 TyKind::BoundVar(BoundVar::new(
288 idx as usize + parent_params + self_params + list_params,
292 ImplTraitLoweringMode::Disallowed => {
293 // FIXME: report error
294 TyKind::Error.intern(&Interner)
298 TypeRef::Macro(macro_call) => {
299 let (expander, recursion_start) = {
300 let mut expander = self.expander.borrow_mut();
301 if expander.is_some() {
302 (Some(expander), false)
304 if let Some(module_id) = self.resolver.module() {
305 *expander = Some(Expander::new(
310 (Some(expander), true)
316 let ty = if let Some(mut expander) = expander {
317 let expander_mut = expander.as_mut().unwrap();
318 let macro_call = macro_call.to_node(self.db.upcast());
319 match expander_mut.enter_expand::<ast::Type>(self.db.upcast(), macro_call) {
320 Ok(ExpandResult { value: Some((mark, expanded)), .. }) => {
322 LowerCtx::new(self.db.upcast(), expander_mut.current_file_id());
323 let type_ref = TypeRef::from_ast(&ctx, expanded);
326 let ty = self.lower_ty(&type_ref);
332 .exit(self.db.upcast(), mark);
341 *self.expander.borrow_mut() = None;
343 ty.unwrap_or_else(|| TyKind::Error.intern(&Interner))
345 TypeRef::Error => TyKind::Error.intern(&Interner),
350 /// This is only for `generic_predicates_for_param`, where we can't just
351 /// lower the self types of the predicates since that could lead to cycles.
352 /// So we just check here if the `type_ref` resolves to a generic param, and which.
353 fn lower_ty_only_param(&self, type_ref: &TypeRef) -> Option<TypeParamId> {
354 let path = match type_ref {
355 TypeRef::Path(path) => path,
358 if path.type_anchor().is_some() {
361 if path.segments().len() > 1 {
365 match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
366 Some((it, None)) => it,
369 if let TypeNs::GenericParam(param_id) = resolution {
376 pub(crate) fn lower_ty_relative_path(
379 // We need the original resolution to lower `Self::AssocTy` correctly
381 remaining_segments: PathSegments<'_>,
382 ) -> (Ty, Option<TypeNs>) {
383 if remaining_segments.len() == 1 {
384 // resolve unselected assoc types
385 let segment = remaining_segments.first().unwrap();
386 (self.select_associated_type(res, segment), None)
387 } else if remaining_segments.len() > 1 {
388 // FIXME report error (ambiguous associated type)
389 (TyKind::Error.intern(&Interner), None)
395 pub(crate) fn lower_partly_resolved_path(
398 resolved_segment: PathSegment<'_>,
399 remaining_segments: PathSegments<'_>,
401 ) -> (Ty, Option<TypeNs>) {
402 let ty = match resolution {
403 TypeNs::TraitId(trait_) => {
404 // if this is a bare dyn Trait, we'll directly put the required ^0 for the self type in there
405 let self_ty = if remaining_segments.len() == 0 {
407 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0))
414 self.lower_trait_ref_from_resolved_path(trait_, resolved_segment, self_ty);
415 let ty = if remaining_segments.len() == 1 {
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 bounds: crate::make_only_type_binders(
442 QuantifiedWhereClauses::from_iter(
444 Some(crate::wrap_empty_binders(WhereClause::Implemented(
449 lifetime: static_lifetime(),
451 TyKind::Dyn(dyn_ty).intern(&Interner)
455 TypeNs::GenericParam(param_id) => {
456 let generics = generics(
458 self.resolver.generic_def().expect("generics in scope"),
460 match self.type_param_mode {
461 TypeParamLoweringMode::Placeholder => {
462 TyKind::Placeholder(to_placeholder_idx(self.db, param_id))
464 TypeParamLoweringMode::Variable => {
465 let idx = generics.param_idx(param_id).expect("matching generics");
466 TyKind::BoundVar(BoundVar::new(self.in_binders, idx))
471 TypeNs::SelfType(impl_id) => {
472 let generics = generics(self.db.upcast(), impl_id.into());
473 let substs = match self.type_param_mode {
474 TypeParamLoweringMode::Placeholder => generics.type_params_subst(self.db),
475 TypeParamLoweringMode::Variable => generics.bound_vars_subst(self.in_binders),
477 self.db.impl_self_ty(impl_id).substitute(&Interner, &substs)
479 TypeNs::AdtSelfType(adt) => {
480 let generics = generics(self.db.upcast(), adt.into());
481 let substs = match self.type_param_mode {
482 TypeParamLoweringMode::Placeholder => generics.type_params_subst(self.db),
483 TypeParamLoweringMode::Variable => generics.bound_vars_subst(self.in_binders),
485 self.db.ty(adt.into()).substitute(&Interner, &substs)
488 TypeNs::AdtId(it) => self.lower_path_inner(resolved_segment, it.into(), infer_args),
489 TypeNs::BuiltinType(it) => {
490 self.lower_path_inner(resolved_segment, it.into(), infer_args)
492 TypeNs::TypeAliasId(it) => {
493 self.lower_path_inner(resolved_segment, it.into(), infer_args)
495 // FIXME: report error
496 TypeNs::EnumVariantId(_) => return (TyKind::Error.intern(&Interner), None),
498 self.lower_ty_relative_path(ty, Some(resolution), remaining_segments)
501 pub(crate) fn lower_path(&self, path: &Path) -> (Ty, Option<TypeNs>) {
502 // Resolve the path (in type namespace)
503 if let Some(type_ref) = path.type_anchor() {
504 let (ty, res) = self.lower_ty_ext(type_ref);
505 return self.lower_ty_relative_path(ty, res, path.segments());
507 let (resolution, remaining_index) =
508 match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
510 None => return (TyKind::Error.intern(&Interner), None),
512 let (resolved_segment, remaining_segments) = match remaining_index {
514 path.segments().last().expect("resolved path has at least one element"),
517 Some(i) => (path.segments().get(i - 1).unwrap(), path.segments().skip(i)),
519 self.lower_partly_resolved_path(resolution, resolved_segment, remaining_segments, false)
522 fn select_associated_type(&self, res: Option<TypeNs>, segment: PathSegment<'_>) -> Ty {
523 if let Some(res) = res {
524 let ty = associated_type_shorthand_candidates(
527 move |name, t, associated_ty| {
528 if name == segment.name {
529 let substs = match self.type_param_mode {
530 TypeParamLoweringMode::Placeholder => {
531 // if we're lowering to placeholders, we have to put
533 let generics = generics(
535 self.resolver.generic_def().expect(
536 "there should be generics if there's a generic param",
539 let s = generics.type_params_subst(self.db);
540 s.apply(t.substitution.clone(), &Interner)
542 TypeParamLoweringMode::Variable => t.substitution.clone(),
544 // We need to shift in the bound vars, since
545 // associated_type_shorthand_candidates does not do that
546 let substs = substs.shifted_in_from(&Interner, self.in_binders);
547 // FIXME handle type parameters on the segment
549 TyKind::Alias(AliasTy::Projection(ProjectionTy {
550 associated_ty_id: to_assoc_type_id(associated_ty),
551 substitution: substs,
561 ty.unwrap_or_else(|| TyKind::Error.intern(&Interner))
563 TyKind::Error.intern(&Interner)
569 segment: PathSegment<'_>,
573 let generic_def = match typeable {
574 TyDefId::BuiltinType(_) => None,
575 TyDefId::AdtId(it) => Some(it.into()),
576 TyDefId::TypeAliasId(it) => Some(it.into()),
578 let substs = self.substs_from_path_segment(segment, generic_def, infer_args, None);
579 self.db.ty(typeable).substitute(&Interner, &substs)
582 /// Collect generic arguments from a path into a `Substs`. See also
583 /// `create_substs_for_ast_path` and `def_to_ty` in rustc.
584 pub(super) fn substs_from_path(
587 // Note that we don't call `db.value_type(resolved)` here,
588 // `ValueTyDefId` is just a convenient way to pass generics and
589 // special-case enum variants
590 resolved: ValueTyDefId,
593 let last = path.segments().last().expect("path should have at least one segment");
594 let (segment, generic_def) = match resolved {
595 ValueTyDefId::FunctionId(it) => (last, Some(it.into())),
596 ValueTyDefId::StructId(it) => (last, Some(it.into())),
597 ValueTyDefId::UnionId(it) => (last, Some(it.into())),
598 ValueTyDefId::ConstId(it) => (last, Some(it.into())),
599 ValueTyDefId::StaticId(_) => (last, None),
600 ValueTyDefId::EnumVariantId(var) => {
601 // the generic args for an enum variant may be either specified
602 // on the segment referring to the enum, or on the segment
603 // referring to the variant. So `Option::<T>::None` and
604 // `Option::None::<T>` are both allowed (though the former is
605 // preferred). See also `def_ids_for_path_segments` in rustc.
606 let len = path.segments().len();
607 let penultimate = if len >= 2 { path.segments().get(len - 2) } else { None };
608 let segment = match penultimate {
609 Some(segment) if segment.args_and_bindings.is_some() => segment,
612 (segment, Some(var.parent.into()))
615 self.substs_from_path_segment(segment, generic_def, infer_args, None)
618 fn substs_from_path_segment(
620 segment: PathSegment<'_>,
621 def_generic: Option<GenericDefId>,
623 explicit_self_ty: Option<Ty>,
625 let mut substs = Vec::new();
626 let def_generics = def_generic.map(|def| generics(self.db.upcast(), def));
628 let (parent_params, self_params, type_params, impl_trait_params) =
629 def_generics.map_or((0, 0, 0, 0), |g| g.provenance_split());
630 let total_len = parent_params + self_params + type_params + impl_trait_params;
632 substs.extend(iter::repeat(TyKind::Error.intern(&Interner)).take(parent_params));
634 let fill_self_params = || {
638 .chain(iter::repeat(TyKind::Error.intern(&Interner)))
642 let mut had_explicit_type_args = false;
644 if let Some(generic_args) = &segment.args_and_bindings {
645 if !generic_args.has_self_type {
649 if generic_args.has_self_type { self_params + type_params } else { type_params };
650 let skip = if generic_args.has_self_type && self_params == 0 { 1 } else { 0 };
651 // if args are provided, it should be all of them, but we can't rely on that
652 for arg in generic_args
655 .filter(|arg| matches!(arg, GenericArg::Type(_)))
660 GenericArg::Type(type_ref) => {
661 had_explicit_type_args = true;
662 let ty = self.lower_ty(type_ref);
665 GenericArg::Lifetime(_) => {}
672 // handle defaults. In expression or pattern path segments without
673 // explicitly specified type arguments, missing type arguments are inferred
674 // (i.e. defaults aren't used).
675 if !infer_args || had_explicit_type_args {
676 if let Some(def_generic) = def_generic {
677 let defaults = self.db.generic_defaults(def_generic);
678 assert_eq!(total_len, defaults.len());
680 for default_ty in defaults.iter().skip(substs.len()) {
681 // each default can depend on the previous parameters
682 let substs_so_far = Substitution::from_iter(&Interner, substs.clone());
683 substs.push(default_ty.clone().substitute(&Interner, &substs_so_far));
688 // add placeholders for args that were not provided
689 // FIXME: emit diagnostics in contexts where this is not allowed
690 for _ in substs.len()..total_len {
691 substs.push(TyKind::Error.intern(&Interner));
693 assert_eq!(substs.len(), total_len);
695 Substitution::from_iter(&Interner, substs)
698 fn lower_trait_ref_from_path(
701 explicit_self_ty: Option<Ty>,
702 ) -> Option<TraitRef> {
704 match self.resolver.resolve_path_in_type_ns_fully(self.db.upcast(), path.mod_path())? {
705 TypeNs::TraitId(tr) => tr,
708 let segment = path.segments().last().expect("path should have at least one segment");
709 Some(self.lower_trait_ref_from_resolved_path(resolved, segment, explicit_self_ty))
712 pub(crate) fn lower_trait_ref_from_resolved_path(
715 segment: PathSegment<'_>,
716 explicit_self_ty: Option<Ty>,
718 let substs = self.trait_ref_substs_from_path(segment, resolved, explicit_self_ty);
719 TraitRef { trait_id: to_chalk_trait_id(resolved), substitution: substs }
724 trait_ref: &HirTraitRef,
725 explicit_self_ty: Option<Ty>,
726 ) -> Option<TraitRef> {
727 self.lower_trait_ref_from_path(&trait_ref.path, explicit_self_ty)
730 fn trait_ref_substs_from_path(
732 segment: PathSegment<'_>,
734 explicit_self_ty: Option<Ty>,
736 self.substs_from_path_segment(segment, Some(resolved.into()), false, explicit_self_ty)
739 pub(crate) fn lower_where_predicate(
741 where_predicate: &'a WherePredicate,
742 ignore_bindings: bool,
743 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
744 match where_predicate {
745 WherePredicate::ForLifetime { target, bound, .. }
746 | WherePredicate::TypeBound { target, bound } => {
747 let self_ty = match target {
748 WherePredicateTypeTarget::TypeRef(type_ref) => self.lower_ty(type_ref),
749 WherePredicateTypeTarget::TypeParam(param_id) => {
750 let generic_def = self.resolver.generic_def().expect("generics in scope");
751 let generics = generics(self.db.upcast(), generic_def);
753 hir_def::TypeParamId { parent: generic_def, local_id: *param_id };
754 let placeholder = to_placeholder_idx(self.db, param_id);
755 match self.type_param_mode {
756 TypeParamLoweringMode::Placeholder => TyKind::Placeholder(placeholder),
757 TypeParamLoweringMode::Variable => {
758 let idx = generics.param_idx(param_id).expect("matching generics");
759 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, idx))
765 self.lower_type_bound(bound, self_ty, ignore_bindings)
769 WherePredicate::Lifetime { .. } => vec![].into_iter(),
773 pub(crate) fn lower_type_bound(
775 bound: &'a TypeBound,
777 ignore_bindings: bool,
778 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
779 let mut bindings = None;
780 let trait_ref = match bound {
781 TypeBound::Path(path) => {
782 bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
783 bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
785 TypeBound::ForLifetime(_, path) => {
786 // FIXME Don't silently drop the hrtb lifetimes here
787 bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
788 bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
790 TypeBound::Lifetime(_) => None,
791 TypeBound::Error => None,
793 trait_ref.into_iter().chain(
796 .filter(move |_| !ignore_bindings)
797 .flat_map(move |tr| self.assoc_type_bindings_from_type_bound(bound, tr)),
801 fn assoc_type_bindings_from_type_bound(
803 bound: &'a TypeBound,
805 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
806 let last_segment = match bound {
807 TypeBound::Path(path) | TypeBound::ForLifetime(_, path) => path.segments().last(),
808 TypeBound::Error | TypeBound::Lifetime(_) => None,
812 .flat_map(|segment| segment.args_and_bindings.into_iter())
813 .flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
814 .flat_map(move |binding| {
815 let found = associated_type_by_name_including_super_traits(
820 let (super_trait_ref, associated_ty) = match found {
821 None => return SmallVec::<[QuantifiedWhereClause; 1]>::new(),
824 let projection_ty = ProjectionTy {
825 associated_ty_id: to_assoc_type_id(associated_ty),
826 substitution: super_trait_ref.substitution,
828 let mut preds = SmallVec::with_capacity(
829 binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
831 if let Some(type_ref) = &binding.type_ref {
832 let ty = self.lower_ty(type_ref);
834 AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty };
835 preds.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq)));
837 for bound in &binding.bounds {
838 preds.extend(self.lower_type_bound(
840 TyKind::Alias(AliasTy::Projection(projection_ty.clone())).intern(&Interner),
848 fn lower_impl_trait(&self, bounds: &[Interned<TypeBound>]) -> ReturnTypeImplTrait {
849 cov_mark::hit!(lower_rpit);
851 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(&Interner);
852 let predicates = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
853 bounds.iter().flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false)).collect()
855 ReturnTypeImplTrait { bounds: crate::make_only_type_binders(1, predicates) }
859 fn count_impl_traits(type_ref: &TypeRef) -> usize {
861 type_ref.walk(&mut |type_ref| {
862 if matches!(type_ref, TypeRef::ImplTrait(_)) {
869 /// Build the signature of a callable item (function, struct or enum variant).
870 pub fn callable_item_sig(db: &dyn HirDatabase, def: CallableDefId) -> PolyFnSig {
872 CallableDefId::FunctionId(f) => fn_sig_for_fn(db, f),
873 CallableDefId::StructId(s) => fn_sig_for_struct_constructor(db, s),
874 CallableDefId::EnumVariantId(e) => fn_sig_for_enum_variant_constructor(db, e),
878 pub fn associated_type_shorthand_candidates<R>(
879 db: &dyn HirDatabase,
881 mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>,
883 let mut search = |t| {
884 for t in all_super_trait_refs(db, t) {
885 let data = db.trait_data(t.hir_trait_id());
887 for (name, assoc_id) in &data.items {
888 if let AssocItemId::TypeAliasId(alias) = assoc_id {
889 if let Some(result) = cb(name, &t, *alias) {
899 TypeNs::SelfType(impl_id) => search(
900 // we're _in_ the impl -- the binders get added back later. Correct,
901 // but it would be nice to make this more explicit
902 db.impl_trait(impl_id)?.into_value_and_skipped_binders().0,
904 TypeNs::GenericParam(param_id) => {
905 let predicates = db.generic_predicates_for_param(param_id);
906 let res = predicates.iter().find_map(|pred| match pred.skip_binders().skip_binders() {
907 // FIXME: how to correctly handle higher-ranked bounds here?
908 WhereClause::Implemented(tr) => search(
910 .shifted_out_to(&Interner, DebruijnIndex::ONE)
911 .expect("FIXME unexpected higher-ranked trait bound"),
915 if let res @ Some(_) = res {
918 // Handle `Self::Type` referring to own associated type in trait definitions
919 if let GenericDefId::TraitId(trait_id) = param_id.parent {
920 let generics = generics(db.upcast(), trait_id.into());
921 if generics.params.types[param_id.local_id].provenance
922 == TypeParamProvenance::TraitSelf
924 let trait_ref = TyBuilder::trait_ref(db, trait_id)
925 .fill_with_bound_vars(DebruijnIndex::INNERMOST, 0)
927 return search(trait_ref);
936 /// Build the type of all specific fields of a struct or enum variant.
937 pub(crate) fn field_types_query(
938 db: &dyn HirDatabase,
939 variant_id: VariantId,
940 ) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>> {
941 let var_data = variant_id.variant_data(db.upcast());
942 let (resolver, def): (_, GenericDefId) = match variant_id {
943 VariantId::StructId(it) => (it.resolver(db.upcast()), it.into()),
944 VariantId::UnionId(it) => (it.resolver(db.upcast()), it.into()),
945 VariantId::EnumVariantId(it) => (it.parent.resolver(db.upcast()), it.parent.into()),
947 let generics = generics(db.upcast(), def);
948 let mut res = ArenaMap::default();
950 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
951 for (field_id, field_data) in var_data.fields().iter() {
952 res.insert(field_id, make_binders(&generics, ctx.lower_ty(&field_data.type_ref)))
957 /// This query exists only to be used when resolving short-hand associated types
960 /// See the analogous query in rustc and its comment:
961 /// <https://github.com/rust-lang/rust/blob/9150f844e2624eb013ec78ca08c1d416e6644026/src/librustc_typeck/astconv.rs#L46>
962 /// This is a query mostly to handle cycles somewhat gracefully; e.g. the
963 /// following bounds are disallowed: `T: Foo<U::Item>, U: Foo<T::Item>`, but
964 /// these are fine: `T: Foo<U::Item>, U: Foo<()>`.
965 pub(crate) fn generic_predicates_for_param_query(
966 db: &dyn HirDatabase,
967 param_id: TypeParamId,
968 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
969 let resolver = param_id.parent.resolver(db.upcast());
971 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
972 let generics = generics(db.upcast(), param_id.parent);
974 .where_predicates_in_scope()
975 // we have to filter out all other predicates *first*, before attempting to lower them
976 .filter(|pred| match pred {
977 WherePredicate::ForLifetime { target, .. }
978 | WherePredicate::TypeBound { target, .. } => match target {
979 WherePredicateTypeTarget::TypeRef(type_ref) => {
980 ctx.lower_ty_only_param(type_ref) == Some(param_id)
982 WherePredicateTypeTarget::TypeParam(local_id) => *local_id == param_id.local_id,
984 WherePredicate::Lifetime { .. } => false,
986 .flat_map(|pred| ctx.lower_where_predicate(pred, true).map(|p| make_binders(&generics, p)))
990 pub(crate) fn generic_predicates_for_param_recover(
991 _db: &dyn HirDatabase,
993 _param_id: &TypeParamId,
994 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
998 pub(crate) fn trait_environment_query(
999 db: &dyn HirDatabase,
1001 ) -> Arc<TraitEnvironment> {
1002 let resolver = def.resolver(db.upcast());
1003 let ctx = TyLoweringContext::new(db, &resolver)
1004 .with_type_param_mode(TypeParamLoweringMode::Placeholder);
1005 let mut traits_in_scope = Vec::new();
1006 let mut clauses = Vec::new();
1007 for pred in resolver.where_predicates_in_scope() {
1008 for pred in ctx.lower_where_predicate(pred, false) {
1009 if let WhereClause::Implemented(tr) = &pred.skip_binders() {
1011 .push((tr.self_type_parameter(&Interner).clone(), tr.hir_trait_id()));
1013 let program_clause: chalk_ir::ProgramClause<Interner> = pred.clone().cast(&Interner);
1014 clauses.push(program_clause.into_from_env_clause(&Interner));
1018 let container: Option<AssocContainerId> = match def {
1019 // FIXME: is there a function for this?
1020 GenericDefId::FunctionId(f) => Some(f.lookup(db.upcast()).container),
1021 GenericDefId::AdtId(_) => None,
1022 GenericDefId::TraitId(_) => None,
1023 GenericDefId::TypeAliasId(t) => Some(t.lookup(db.upcast()).container),
1024 GenericDefId::ImplId(_) => None,
1025 GenericDefId::EnumVariantId(_) => None,
1026 GenericDefId::ConstId(c) => Some(c.lookup(db.upcast()).container),
1028 if let Some(AssocContainerId::TraitId(trait_id)) = container {
1029 // add `Self: Trait<T1, T2, ...>` to the environment in trait
1030 // function default implementations (and speculative code
1031 // inside consts or type aliases)
1032 cov_mark::hit!(trait_self_implements_self);
1033 let substs = TyBuilder::type_params_subst(db, trait_id);
1034 let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs };
1035 let pred = WhereClause::Implemented(trait_ref);
1036 let program_clause: chalk_ir::ProgramClause<Interner> = pred.cast(&Interner);
1037 clauses.push(program_clause.into_from_env_clause(&Interner));
1040 let krate = def.module(db.upcast()).krate();
1042 let env = chalk_ir::Environment::new(&Interner).add_clauses(&Interner, clauses);
1044 Arc::new(TraitEnvironment { krate, traits_from_clauses: traits_in_scope, env })
1047 /// Resolve the where clause(s) of an item with generics.
1048 pub(crate) fn generic_predicates_query(
1049 db: &dyn HirDatabase,
1051 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
1052 let resolver = def.resolver(db.upcast());
1054 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1055 let generics = generics(db.upcast(), def);
1057 .where_predicates_in_scope()
1058 .flat_map(|pred| ctx.lower_where_predicate(pred, false).map(|p| make_binders(&generics, p)))
1062 /// Resolve the default type params from generics
1063 pub(crate) fn generic_defaults_query(
1064 db: &dyn HirDatabase,
1066 ) -> Arc<[Binders<Ty>]> {
1067 let resolver = def.resolver(db.upcast());
1069 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1070 let generic_params = generics(db.upcast(), def);
1072 let defaults = generic_params
1075 .map(|(idx, (_, p))| {
1077 p.default.as_ref().map_or(TyKind::Error.intern(&Interner), |t| ctx.lower_ty(t));
1079 // Each default can only refer to previous parameters.
1080 ty = crate::fold_free_vars(ty, |bound, binders| {
1081 if bound.index >= idx && bound.debruijn == DebruijnIndex::INNERMOST {
1082 // type variable default referring to parameter coming
1083 // after it. This is forbidden (FIXME: report
1085 TyKind::Error.intern(&Interner)
1087 bound.shifted_in_from(binders).to_ty(&Interner)
1091 crate::make_only_type_binders(idx, ty)
1098 pub(crate) fn generic_defaults_recover(
1099 db: &dyn HirDatabase,
1102 ) -> Arc<[Binders<Ty>]> {
1103 let generic_params = generics(db.upcast(), *def);
1105 // we still need one default per parameter
1106 let defaults = generic_params
1110 let ty = TyKind::Error.intern(&Interner);
1112 crate::make_only_type_binders(idx, ty)
1119 fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
1120 let data = db.function_data(def);
1121 let resolver = def.resolver(db.upcast());
1122 let ctx_params = TyLoweringContext::new(db, &resolver)
1123 .with_impl_trait_mode(ImplTraitLoweringMode::Variable)
1124 .with_type_param_mode(TypeParamLoweringMode::Variable);
1125 let params = data.params.iter().map(|tr| ctx_params.lower_ty(tr)).collect::<Vec<_>>();
1126 let ctx_ret = TyLoweringContext::new(db, &resolver)
1127 .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
1128 .with_type_param_mode(TypeParamLoweringMode::Variable);
1129 let ret = ctx_ret.lower_ty(&data.ret_type);
1130 let generics = generics(db.upcast(), def.into());
1131 make_binders(&generics, CallableSig::from_params_and_return(params, ret, data.is_varargs()))
1134 /// Build the declared type of a function. This should not need to look at the
1136 fn type_for_fn(db: &dyn HirDatabase, def: FunctionId) -> Binders<Ty> {
1137 let generics = generics(db.upcast(), def.into());
1138 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1141 TyKind::FnDef(CallableDefId::FunctionId(def).to_chalk(db), substs).intern(&Interner),
1145 /// Build the declared type of a const.
1146 fn type_for_const(db: &dyn HirDatabase, def: ConstId) -> Binders<Ty> {
1147 let data = db.const_data(def);
1148 let generics = generics(db.upcast(), def.into());
1149 let resolver = def.resolver(db.upcast());
1151 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1153 make_binders(&generics, ctx.lower_ty(&data.type_ref))
1156 /// Build the declared type of a static.
1157 fn type_for_static(db: &dyn HirDatabase, def: StaticId) -> Binders<Ty> {
1158 let data = db.static_data(def);
1159 let resolver = def.resolver(db.upcast());
1160 let ctx = TyLoweringContext::new(db, &resolver);
1162 Binders::empty(&Interner, ctx.lower_ty(&data.type_ref))
1165 fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnSig {
1166 let struct_data = db.struct_data(def);
1167 let fields = struct_data.variant_data.fields();
1168 let resolver = def.resolver(db.upcast());
1170 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1171 let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
1172 let (ret, binders) = type_for_adt(db, def.into()).into_value_and_skipped_binders();
1173 Binders::new(binders, CallableSig::from_params_and_return(params, ret, false))
1176 /// Build the type of a tuple struct constructor.
1177 fn type_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> Binders<Ty> {
1178 let struct_data = db.struct_data(def);
1179 if let StructKind::Unit = struct_data.variant_data.kind() {
1180 return type_for_adt(db, def.into());
1182 let generics = generics(db.upcast(), def.into());
1183 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1186 TyKind::FnDef(CallableDefId::StructId(def).to_chalk(db), substs).intern(&Interner),
1190 fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> PolyFnSig {
1191 let enum_data = db.enum_data(def.parent);
1192 let var_data = &enum_data.variants[def.local_id];
1193 let fields = var_data.variant_data.fields();
1194 let resolver = def.parent.resolver(db.upcast());
1196 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1197 let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
1198 let (ret, binders) = type_for_adt(db, def.parent.into()).into_value_and_skipped_binders();
1199 Binders::new(binders, CallableSig::from_params_and_return(params, ret, false))
1202 /// Build the type of a tuple enum variant constructor.
1203 fn type_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> Binders<Ty> {
1204 let enum_data = db.enum_data(def.parent);
1205 let var_data = &enum_data.variants[def.local_id].variant_data;
1206 if let StructKind::Unit = var_data.kind() {
1207 return type_for_adt(db, def.parent.into());
1209 let generics = generics(db.upcast(), def.parent.into());
1210 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1213 TyKind::FnDef(CallableDefId::EnumVariantId(def).to_chalk(db), substs).intern(&Interner),
1217 fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
1218 let generics = generics(db.upcast(), adt.into());
1219 let b = TyBuilder::adt(db, adt);
1220 let ty = b.fill_with_bound_vars(DebruijnIndex::INNERMOST, 0).build();
1221 make_binders(&generics, ty)
1224 fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
1225 let generics = generics(db.upcast(), t.into());
1226 let resolver = t.resolver(db.upcast());
1228 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1229 if db.type_alias_data(t).is_extern {
1230 Binders::empty(&Interner, TyKind::Foreign(crate::to_foreign_def_id(t)).intern(&Interner))
1232 let type_ref = &db.type_alias_data(t).type_ref;
1233 let inner = ctx.lower_ty(type_ref.as_deref().unwrap_or(&TypeRef::Error));
1234 make_binders(&generics, inner)
1238 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
1239 pub enum CallableDefId {
1240 FunctionId(FunctionId),
1242 EnumVariantId(EnumVariantId),
1244 impl_from!(FunctionId, StructId, EnumVariantId for CallableDefId);
1246 impl CallableDefId {
1247 pub fn krate(self, db: &dyn HirDatabase) -> CrateId {
1248 let db = db.upcast();
1250 CallableDefId::FunctionId(f) => f.lookup(db).module(db),
1251 CallableDefId::StructId(s) => s.lookup(db).container,
1252 CallableDefId::EnumVariantId(e) => e.parent.lookup(db).container,
1258 impl From<CallableDefId> for GenericDefId {
1259 fn from(def: CallableDefId) -> GenericDefId {
1261 CallableDefId::FunctionId(f) => f.into(),
1262 CallableDefId::StructId(s) => s.into(),
1263 CallableDefId::EnumVariantId(e) => e.into(),
1268 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1270 BuiltinType(BuiltinType),
1272 TypeAliasId(TypeAliasId),
1274 impl_from!(BuiltinType, AdtId(StructId, EnumId, UnionId), TypeAliasId for TyDefId);
1276 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1277 pub enum ValueTyDefId {
1278 FunctionId(FunctionId),
1281 EnumVariantId(EnumVariantId),
1285 impl_from!(FunctionId, StructId, UnionId, EnumVariantId, ConstId, StaticId for ValueTyDefId);
1287 /// Build the declared type of an item. This depends on the namespace; e.g. for
1288 /// `struct Foo(usize)`, we have two types: The type of the struct itself, and
1289 /// the constructor function `(usize) -> Foo` which lives in the values
1291 pub(crate) fn ty_query(db: &dyn HirDatabase, def: TyDefId) -> Binders<Ty> {
1293 TyDefId::BuiltinType(it) => Binders::empty(&Interner, TyBuilder::builtin(it)),
1294 TyDefId::AdtId(it) => type_for_adt(db, it),
1295 TyDefId::TypeAliasId(it) => type_for_type_alias(db, it),
1299 pub(crate) fn ty_recover(db: &dyn HirDatabase, _cycle: &[String], def: &TyDefId) -> Binders<Ty> {
1300 let generics = match *def {
1301 TyDefId::BuiltinType(_) => {
1302 return Binders::empty(&Interner, TyKind::Error.intern(&Interner))
1304 TyDefId::AdtId(it) => generics(db.upcast(), it.into()),
1305 TyDefId::TypeAliasId(it) => generics(db.upcast(), it.into()),
1307 make_binders(&generics, TyKind::Error.intern(&Interner))
1310 pub(crate) fn value_ty_query(db: &dyn HirDatabase, def: ValueTyDefId) -> Binders<Ty> {
1312 ValueTyDefId::FunctionId(it) => type_for_fn(db, it),
1313 ValueTyDefId::StructId(it) => type_for_struct_constructor(db, it),
1314 ValueTyDefId::UnionId(it) => type_for_adt(db, it.into()),
1315 ValueTyDefId::EnumVariantId(it) => type_for_enum_variant_constructor(db, it),
1316 ValueTyDefId::ConstId(it) => type_for_const(db, it),
1317 ValueTyDefId::StaticId(it) => type_for_static(db, it),
1321 pub(crate) fn impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binders<Ty> {
1322 let impl_data = db.impl_data(impl_id);
1323 let resolver = impl_id.resolver(db.upcast());
1324 let generics = generics(db.upcast(), impl_id.into());
1326 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1327 make_binders(&generics, ctx.lower_ty(&impl_data.self_ty))
1330 pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
1331 let parent_data = db.generic_params(def.parent);
1332 let data = &parent_data.consts[def.local_id];
1333 let resolver = def.parent.resolver(db.upcast());
1334 let ctx = TyLoweringContext::new(db, &resolver);
1336 ctx.lower_ty(&data.ty)
1339 pub(crate) fn impl_self_ty_recover(
1340 db: &dyn HirDatabase,
1344 let generics = generics(db.upcast(), (*impl_id).into());
1345 make_binders(&generics, TyKind::Error.intern(&Interner))
1348 pub(crate) fn impl_trait_query(db: &dyn HirDatabase, impl_id: ImplId) -> Option<Binders<TraitRef>> {
1349 let impl_data = db.impl_data(impl_id);
1350 let resolver = impl_id.resolver(db.upcast());
1352 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1353 let (self_ty, binders) = db.impl_self_ty(impl_id).into_value_and_skipped_binders();
1354 let target_trait = impl_data.target_trait.as_ref()?;
1355 Some(Binders::new(binders, ctx.lower_trait_ref(target_trait, Some(self_ty))?))
1358 pub(crate) fn return_type_impl_traits(
1359 db: &dyn HirDatabase,
1360 def: hir_def::FunctionId,
1361 ) -> Option<Arc<Binders<ReturnTypeImplTraits>>> {
1362 // FIXME unify with fn_sig_for_fn instead of doing lowering twice, maybe
1363 let data = db.function_data(def);
1364 let resolver = def.resolver(db.upcast());
1365 let ctx_ret = TyLoweringContext::new(db, &resolver)
1366 .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
1367 .with_type_param_mode(TypeParamLoweringMode::Variable);
1368 let _ret = (&ctx_ret).lower_ty(&data.ret_type);
1369 let generics = generics(db.upcast(), def.into());
1370 let return_type_impl_traits =
1371 ReturnTypeImplTraits { impl_traits: ctx_ret.opaque_type_data.into_inner() };
1372 if return_type_impl_traits.impl_traits.is_empty() {
1375 Some(Arc::new(make_binders(&generics, return_type_impl_traits)))
1379 pub(crate) fn lower_to_chalk_mutability(m: hir_def::type_ref::Mutability) -> Mutability {
1381 hir_def::type_ref::Mutability::Shared => Mutability::Not,
1382 hir_def::type_ref::Mutability::Mut => Mutability::Mut,
1386 fn make_binders<T: HasInterner<Interner = Interner>>(generics: &Generics, value: T) -> Binders<T> {
1387 crate::make_only_type_binders(generics.len(), value)