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, AssocItemId, ConstId, ConstParamId, EnumId, EnumVariantId, FunctionId, GenericDefId,
23 HasModule, ImplId, ItemContainerId, 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;
31 use syntax::{ast, SmolStr};
33 use crate::all_super_traits;
38 static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx,
40 all_super_trait_refs, associated_type_by_name_including_super_traits, generics, Generics,
42 AliasEq, AliasTy, Binders, BoundVar, CallableSig, DebruijnIndex, DynTy, FnPointer, FnSig,
43 FnSubst, ImplTraitId, Interner, PolyFnSig, ProjectionTy, QuantifiedWhereClause,
44 QuantifiedWhereClauses, ReturnTypeImplTrait, ReturnTypeImplTraits, Substitution,
45 TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyKind, WhereClause,
49 pub struct TyLoweringContext<'a> {
50 pub db: &'a dyn HirDatabase,
51 pub resolver: &'a Resolver,
52 in_binders: DebruijnIndex,
53 /// Note: Conceptually, it's thinkable that we could be in a location where
54 /// some type params should be represented as placeholders, and others
55 /// should be converted to variables. I think in practice, this isn't
56 /// possible currently, so this should be fine for now.
57 pub type_param_mode: TypeParamLoweringMode,
58 pub impl_trait_mode: ImplTraitLoweringMode,
59 impl_trait_counter: Cell<u16>,
60 /// When turning `impl Trait` into opaque types, we have to collect the
61 /// bounds at the same time to get the IDs correct (without becoming too
62 /// complicated). I don't like using interior mutability (as for the
63 /// counter), but I've tried and failed to make the lifetimes work for
64 /// passing around a `&mut TyLoweringContext`. The core problem is that
65 /// we're grouping the mutable data (the counter and this field) together
66 /// with the immutable context (the references to the DB and resolver).
67 /// Splitting this up would be a possible fix.
68 opaque_type_data: RefCell<Vec<ReturnTypeImplTrait>>,
69 expander: RefCell<Option<Expander>>,
70 /// Tracks types with explicit `?Sized` bounds.
71 pub(crate) unsized_types: RefCell<FxHashSet<Ty>>,
74 impl<'a> TyLoweringContext<'a> {
75 pub fn new(db: &'a dyn HirDatabase, resolver: &'a Resolver) -> Self {
76 let impl_trait_counter = Cell::new(0);
77 let impl_trait_mode = ImplTraitLoweringMode::Disallowed;
78 let type_param_mode = TypeParamLoweringMode::Placeholder;
79 let in_binders = DebruijnIndex::INNERMOST;
80 let opaque_type_data = RefCell::new(Vec::new());
89 expander: RefCell::new(None),
90 unsized_types: RefCell::default(),
94 pub fn with_debruijn<T>(
96 debruijn: DebruijnIndex,
97 f: impl FnOnce(&TyLoweringContext) -> T,
99 let opaque_ty_data_vec = self.opaque_type_data.take();
100 let expander = self.expander.take();
101 let unsized_types = self.unsized_types.take();
103 in_binders: debruijn,
104 impl_trait_counter: Cell::new(self.impl_trait_counter.get()),
105 opaque_type_data: RefCell::new(opaque_ty_data_vec),
106 expander: RefCell::new(expander),
107 unsized_types: RefCell::new(unsized_types),
110 let result = f(&new_ctx);
111 self.impl_trait_counter.set(new_ctx.impl_trait_counter.get());
112 self.opaque_type_data.replace(new_ctx.opaque_type_data.into_inner());
113 self.expander.replace(new_ctx.expander.into_inner());
114 self.unsized_types.replace(new_ctx.unsized_types.into_inner());
118 pub fn with_shifted_in<T>(
120 debruijn: DebruijnIndex,
121 f: impl FnOnce(&TyLoweringContext) -> T,
123 self.with_debruijn(self.in_binders.shifted_in_from(debruijn), f)
126 pub fn with_impl_trait_mode(self, impl_trait_mode: ImplTraitLoweringMode) -> Self {
127 Self { impl_trait_mode, ..self }
130 pub fn with_type_param_mode(self, type_param_mode: TypeParamLoweringMode) -> Self {
131 Self { type_param_mode, ..self }
135 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
136 pub enum ImplTraitLoweringMode {
137 /// `impl Trait` gets lowered into an opaque type that doesn't unify with
138 /// anything except itself. This is used in places where values flow 'out',
139 /// i.e. for arguments of the function we're currently checking, and return
140 /// types of functions we're calling.
142 /// `impl Trait` gets lowered into a type variable. Used for argument
143 /// position impl Trait when inside the respective function, since it allows
144 /// us to support that without Chalk.
146 /// `impl Trait` gets lowered into a variable that can unify with some
147 /// type. This is used in places where values flow 'in', i.e. for arguments
148 /// of functions we're calling, and the return type of the function we're
149 /// currently checking.
151 /// `impl Trait` is disallowed and will be an error.
155 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
156 pub enum TypeParamLoweringMode {
161 impl<'a> TyLoweringContext<'a> {
162 pub fn lower_ty(&self, type_ref: &TypeRef) -> Ty {
163 self.lower_ty_ext(type_ref).0
166 pub fn lower_ty_ext(&self, type_ref: &TypeRef) -> (Ty, Option<TypeNs>) {
168 let ty = match type_ref {
169 TypeRef::Never => TyKind::Never.intern(Interner),
170 TypeRef::Tuple(inner) => {
171 let inner_tys = inner.iter().map(|tr| self.lower_ty(tr));
172 TyKind::Tuple(inner_tys.len(), Substitution::from_iter(Interner, inner_tys))
175 TypeRef::Path(path) => {
176 let (ty, res_) = self.lower_path(path);
180 TypeRef::RawPtr(inner, mutability) => {
181 let inner_ty = self.lower_ty(inner);
182 TyKind::Raw(lower_to_chalk_mutability(*mutability), inner_ty).intern(Interner)
184 TypeRef::Array(inner, len) => {
185 let inner_ty = self.lower_ty(inner);
187 let const_len = consteval::usize_const(len.as_usize());
189 TyKind::Array(inner_ty, const_len).intern(Interner)
191 TypeRef::Slice(inner) => {
192 let inner_ty = self.lower_ty(inner);
193 TyKind::Slice(inner_ty).intern(Interner)
195 TypeRef::Reference(inner, _, mutability) => {
196 let inner_ty = self.lower_ty(inner);
197 let lifetime = static_lifetime();
198 TyKind::Ref(lower_to_chalk_mutability(*mutability), lifetime, inner_ty)
201 TypeRef::Placeholder => TyKind::Error.intern(Interner),
202 TypeRef::Fn(params, is_varargs) => {
203 let substs = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
204 Substitution::from_iter(Interner, params.iter().map(|(_, tr)| ctx.lower_ty(tr)))
206 TyKind::Function(FnPointer {
207 num_binders: 0, // FIXME lower `for<'a> fn()` correctly
208 sig: FnSig { abi: (), safety: Safety::Safe, variadic: *is_varargs },
209 substitution: FnSubst(substs),
213 TypeRef::DynTrait(bounds) => {
215 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(Interner);
216 let bounds = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
217 QuantifiedWhereClauses::from_iter(
219 bounds.iter().flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false)),
222 let bounds = crate::make_only_type_binders(1, bounds);
223 TyKind::Dyn(DynTy { bounds, lifetime: static_lifetime() }).intern(Interner)
225 TypeRef::ImplTrait(bounds) => {
226 match self.impl_trait_mode {
227 ImplTraitLoweringMode::Opaque => {
228 let idx = self.impl_trait_counter.get();
229 self.impl_trait_counter.set(idx + 1);
230 let func = match self.resolver.generic_def() {
231 Some(GenericDefId::FunctionId(f)) => f,
232 _ => panic!("opaque impl trait lowering in non-function"),
235 assert!(idx as usize == self.opaque_type_data.borrow().len());
236 // this dance is to make sure the data is in the right
237 // place even if we encounter more opaque types while
238 // lowering the bounds
239 self.opaque_type_data.borrow_mut().push(ReturnTypeImplTrait {
240 bounds: crate::make_only_type_binders(1, Vec::new()),
242 // We don't want to lower the bounds inside the binders
243 // we're currently in, because they don't end up inside
244 // those binders. E.g. when we have `impl Trait<impl
245 // OtherTrait<T>>`, the `impl OtherTrait<T>` can't refer
246 // to the self parameter from `impl Trait`, and the
247 // bounds aren't actually stored nested within each
248 // other, but separately. So if the `T` refers to a type
249 // parameter of the outer function, it's just one binder
250 // away instead of two.
251 let actual_opaque_type_data = self
252 .with_debruijn(DebruijnIndex::INNERMOST, |ctx| {
253 ctx.lower_impl_trait(bounds, func)
255 self.opaque_type_data.borrow_mut()[idx as usize] = actual_opaque_type_data;
257 let impl_trait_id = ImplTraitId::ReturnTypeImplTrait(func, idx);
258 let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into();
259 let generics = generics(self.db.upcast(), func.into());
260 let parameters = generics.bound_vars_subst(self.in_binders);
261 TyKind::OpaqueType(opaque_ty_id, parameters).intern(Interner)
263 ImplTraitLoweringMode::Param => {
264 let idx = self.impl_trait_counter.get();
265 // FIXME we're probably doing something wrong here
266 self.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
267 if let Some(def) = self.resolver.generic_def() {
268 let generics = generics(self.db.upcast(), def);
271 .filter(|(_, data)| {
272 data.provenance == TypeParamProvenance::ArgumentImplTrait
275 .map_or(TyKind::Error, |(id, _)| {
276 TyKind::Placeholder(to_placeholder_idx(self.db, id))
278 param.intern(Interner)
280 TyKind::Error.intern(Interner)
283 ImplTraitLoweringMode::Variable => {
284 let idx = self.impl_trait_counter.get();
285 // FIXME we're probably doing something wrong here
286 self.impl_trait_counter.set(idx + count_impl_traits(type_ref) as u16);
287 let (parent_params, self_params, list_params, _impl_trait_params) =
288 if let Some(def) = self.resolver.generic_def() {
289 let generics = generics(self.db.upcast(), def);
290 generics.provenance_split()
294 TyKind::BoundVar(BoundVar::new(
296 idx as usize + parent_params + self_params + list_params,
300 ImplTraitLoweringMode::Disallowed => {
301 // FIXME: report error
302 TyKind::Error.intern(Interner)
306 TypeRef::Macro(macro_call) => {
307 let (expander, recursion_start) = {
308 let mut expander = self.expander.borrow_mut();
309 if expander.is_some() {
310 (Some(expander), false)
311 } else if let Some(module_id) = self.resolver.module() {
313 Some(Expander::new(self.db.upcast(), macro_call.file_id, module_id));
314 (Some(expander), true)
319 let ty = if let Some(mut expander) = expander {
320 let expander_mut = expander.as_mut().unwrap();
321 let macro_call = macro_call.to_node(self.db.upcast());
322 match expander_mut.enter_expand::<ast::Type>(self.db.upcast(), macro_call) {
323 Ok(ExpandResult { value: Some((mark, expanded)), .. }) => {
325 LowerCtx::new(self.db.upcast(), expander_mut.current_file_id());
326 let type_ref = TypeRef::from_ast(&ctx, expanded);
329 let ty = self.lower_ty(&type_ref);
335 .exit(self.db.upcast(), mark);
344 *self.expander.borrow_mut() = None;
346 ty.unwrap_or_else(|| TyKind::Error.intern(Interner))
348 TypeRef::Error => TyKind::Error.intern(Interner),
353 /// This is only for `generic_predicates_for_param`, where we can't just
354 /// lower the self types of the predicates since that could lead to cycles.
355 /// So we just check here if the `type_ref` resolves to a generic param, and which.
356 fn lower_ty_only_param(&self, type_ref: &TypeRef) -> Option<TypeParamId> {
357 let path = match type_ref {
358 TypeRef::Path(path) => path,
361 if path.type_anchor().is_some() {
364 if path.segments().len() > 1 {
368 match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
369 Some((it, None)) => it,
373 TypeNs::GenericParam(param_id) => Some(param_id),
378 pub(crate) fn lower_ty_relative_path(
381 // We need the original resolution to lower `Self::AssocTy` correctly
383 remaining_segments: PathSegments<'_>,
384 ) -> (Ty, Option<TypeNs>) {
385 match remaining_segments.len() {
388 // resolve unselected assoc types
389 let segment = remaining_segments.first().unwrap();
390 (self.select_associated_type(res, segment), None)
393 // FIXME report error (ambiguous associated type)
394 (TyKind::Error.intern(Interner), None)
399 pub(crate) fn lower_partly_resolved_path(
402 resolved_segment: PathSegment<'_>,
403 remaining_segments: PathSegments<'_>,
405 ) -> (Ty, Option<TypeNs>) {
406 let ty = match resolution {
407 TypeNs::TraitId(trait_) => {
408 let ty = match remaining_segments.len() {
411 self.lower_trait_ref_from_resolved_path(trait_, resolved_segment, None);
412 let segment = remaining_segments.first().unwrap();
415 .trait_data(trait_ref.hir_trait_id())
416 .associated_type_by_name(segment.name);
418 Some(associated_ty) => {
419 // FIXME handle type parameters on the segment
420 TyKind::Alias(AliasTy::Projection(ProjectionTy {
421 associated_ty_id: to_assoc_type_id(associated_ty),
422 substitution: trait_ref.substitution,
427 // FIXME: report error (associated type not found)
428 TyKind::Error.intern(Interner)
434 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0))
437 let trait_ref = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
438 ctx.lower_trait_ref_from_resolved_path(
445 bounds: crate::make_only_type_binders(
447 QuantifiedWhereClauses::from_iter(
449 Some(crate::wrap_empty_binders(WhereClause::Implemented(
454 lifetime: static_lifetime(),
456 TyKind::Dyn(dyn_ty).intern(Interner)
459 // FIXME report error (ambiguous associated type)
460 TyKind::Error.intern(Interner)
465 TypeNs::GenericParam(param_id) => {
466 let generics = generics(
468 self.resolver.generic_def().expect("generics in scope"),
470 match self.type_param_mode {
471 TypeParamLoweringMode::Placeholder => {
472 TyKind::Placeholder(to_placeholder_idx(self.db, param_id))
474 TypeParamLoweringMode::Variable => {
475 let idx = generics.param_idx(param_id).expect("matching generics");
476 TyKind::BoundVar(BoundVar::new(self.in_binders, idx))
481 TypeNs::SelfType(impl_id) => {
482 let generics = generics(self.db.upcast(), impl_id.into());
483 let substs = match self.type_param_mode {
484 TypeParamLoweringMode::Placeholder => generics.type_params_subst(self.db),
485 TypeParamLoweringMode::Variable => generics.bound_vars_subst(self.in_binders),
487 self.db.impl_self_ty(impl_id).substitute(Interner, &substs)
489 TypeNs::AdtSelfType(adt) => {
490 let generics = generics(self.db.upcast(), adt.into());
491 let substs = match self.type_param_mode {
492 TypeParamLoweringMode::Placeholder => generics.type_params_subst(self.db),
493 TypeParamLoweringMode::Variable => generics.bound_vars_subst(self.in_binders),
495 self.db.ty(adt.into()).substitute(Interner, &substs)
498 TypeNs::AdtId(it) => self.lower_path_inner(resolved_segment, it.into(), infer_args),
499 TypeNs::BuiltinType(it) => {
500 self.lower_path_inner(resolved_segment, it.into(), infer_args)
502 TypeNs::TypeAliasId(it) => {
503 self.lower_path_inner(resolved_segment, it.into(), infer_args)
505 // FIXME: report error
506 TypeNs::EnumVariantId(_) => return (TyKind::Error.intern(Interner), None),
508 self.lower_ty_relative_path(ty, Some(resolution), remaining_segments)
511 pub(crate) fn lower_path(&self, path: &Path) -> (Ty, Option<TypeNs>) {
512 // Resolve the path (in type namespace)
513 if let Some(type_ref) = path.type_anchor() {
514 let (ty, res) = self.lower_ty_ext(type_ref);
515 return self.lower_ty_relative_path(ty, res, path.segments());
517 let (resolution, remaining_index) =
518 match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
520 None => return (TyKind::Error.intern(Interner), None),
522 let (resolved_segment, remaining_segments) = match remaining_index {
524 path.segments().last().expect("resolved path has at least one element"),
527 Some(i) => (path.segments().get(i - 1).unwrap(), path.segments().skip(i)),
529 self.lower_partly_resolved_path(resolution, resolved_segment, remaining_segments, false)
532 fn select_associated_type(&self, res: Option<TypeNs>, segment: PathSegment<'_>) -> Ty {
533 let (def, res) = match (self.resolver.generic_def(), res) {
534 (Some(def), Some(res)) => (def, res),
535 _ => return TyKind::Error.intern(Interner),
537 let ty = named_associated_type_shorthand_candidates(
541 Some(segment.name.clone()),
542 move |name, t, associated_ty| {
543 if name == segment.name {
544 let substs = match self.type_param_mode {
545 TypeParamLoweringMode::Placeholder => {
546 // if we're lowering to placeholders, we have to put
548 let generics = generics(
552 .expect("there should be generics if there's a generic param"),
554 let s = generics.type_params_subst(self.db);
555 s.apply(t.substitution.clone(), Interner)
557 TypeParamLoweringMode::Variable => t.substitution.clone(),
559 // We need to shift in the bound vars, since
560 // associated_type_shorthand_candidates does not do that
561 let substs = substs.shifted_in_from(Interner, self.in_binders);
562 // FIXME handle type parameters on the segment
564 TyKind::Alias(AliasTy::Projection(ProjectionTy {
565 associated_ty_id: to_assoc_type_id(associated_ty),
566 substitution: substs,
576 ty.unwrap_or_else(|| TyKind::Error.intern(Interner))
581 segment: PathSegment<'_>,
585 let generic_def = match typeable {
586 TyDefId::BuiltinType(_) => None,
587 TyDefId::AdtId(it) => Some(it.into()),
588 TyDefId::TypeAliasId(it) => Some(it.into()),
590 let substs = self.substs_from_path_segment(segment, generic_def, infer_args, None);
591 self.db.ty(typeable).substitute(Interner, &substs)
594 /// Collect generic arguments from a path into a `Substs`. See also
595 /// `create_substs_for_ast_path` and `def_to_ty` in rustc.
596 pub(super) fn substs_from_path(
599 // Note that we don't call `db.value_type(resolved)` here,
600 // `ValueTyDefId` is just a convenient way to pass generics and
601 // special-case enum variants
602 resolved: ValueTyDefId,
605 let last = path.segments().last().expect("path should have at least one segment");
606 let (segment, generic_def) = match resolved {
607 ValueTyDefId::FunctionId(it) => (last, Some(it.into())),
608 ValueTyDefId::StructId(it) => (last, Some(it.into())),
609 ValueTyDefId::UnionId(it) => (last, Some(it.into())),
610 ValueTyDefId::ConstId(it) => (last, Some(it.into())),
611 ValueTyDefId::StaticId(_) => (last, None),
612 ValueTyDefId::EnumVariantId(var) => {
613 // the generic args for an enum variant may be either specified
614 // on the segment referring to the enum, or on the segment
615 // referring to the variant. So `Option::<T>::None` and
616 // `Option::None::<T>` are both allowed (though the former is
617 // preferred). See also `def_ids_for_path_segments` in rustc.
618 let len = path.segments().len();
619 let penultimate = len.checked_sub(2).and_then(|idx| path.segments().get(idx));
620 let segment = match penultimate {
621 Some(segment) if segment.args_and_bindings.is_some() => segment,
624 (segment, Some(var.parent.into()))
627 self.substs_from_path_segment(segment, generic_def, infer_args, None)
630 fn substs_from_path_segment(
632 segment: PathSegment<'_>,
633 def_generic: Option<GenericDefId>,
635 explicit_self_ty: Option<Ty>,
637 let mut substs = Vec::new();
638 let def_generics = def_generic.map(|def| generics(self.db.upcast(), def));
640 let (parent_params, self_params, type_params, impl_trait_params) =
641 def_generics.map_or((0, 0, 0, 0), |g| g.provenance_split());
642 let total_len = parent_params + self_params + type_params + impl_trait_params;
644 substs.extend(iter::repeat(TyKind::Error.intern(Interner)).take(parent_params));
646 let fill_self_params = || {
650 .chain(iter::repeat(TyKind::Error.intern(Interner)))
654 let mut had_explicit_type_args = false;
656 if let Some(generic_args) = &segment.args_and_bindings {
657 if !generic_args.has_self_type {
661 if generic_args.has_self_type { self_params + type_params } else { type_params };
662 let skip = if generic_args.has_self_type && self_params == 0 { 1 } else { 0 };
663 // if args are provided, it should be all of them, but we can't rely on that
664 for arg in generic_args
667 .filter(|arg| matches!(arg, GenericArg::Type(_)))
672 GenericArg::Type(type_ref) => {
673 had_explicit_type_args = true;
674 let ty = self.lower_ty(type_ref);
677 GenericArg::Lifetime(_) => {}
684 // handle defaults. In expression or pattern path segments without
685 // explicitly specified type arguments, missing type arguments are inferred
686 // (i.e. defaults aren't used).
687 if !infer_args || had_explicit_type_args {
688 if let Some(def_generic) = def_generic {
689 let defaults = self.db.generic_defaults(def_generic);
690 assert_eq!(total_len, defaults.len());
692 for default_ty in defaults.iter().skip(substs.len()) {
693 // each default can depend on the previous parameters
694 let substs_so_far = Substitution::from_iter(Interner, substs.clone());
695 substs.push(default_ty.clone().substitute(Interner, &substs_so_far));
700 // add placeholders for args that were not provided
701 // FIXME: emit diagnostics in contexts where this is not allowed
702 for _ in substs.len()..total_len {
703 substs.push(TyKind::Error.intern(Interner));
705 assert_eq!(substs.len(), total_len);
707 Substitution::from_iter(Interner, substs)
710 fn lower_trait_ref_from_path(
713 explicit_self_ty: Option<Ty>,
714 ) -> Option<TraitRef> {
716 match self.resolver.resolve_path_in_type_ns_fully(self.db.upcast(), path.mod_path())? {
717 TypeNs::TraitId(tr) => tr,
720 let segment = path.segments().last().expect("path should have at least one segment");
721 Some(self.lower_trait_ref_from_resolved_path(resolved, segment, explicit_self_ty))
724 pub(crate) fn lower_trait_ref_from_resolved_path(
727 segment: PathSegment<'_>,
728 explicit_self_ty: Option<Ty>,
730 let substs = self.trait_ref_substs_from_path(segment, resolved, explicit_self_ty);
731 TraitRef { trait_id: to_chalk_trait_id(resolved), substitution: substs }
736 trait_ref: &HirTraitRef,
737 explicit_self_ty: Option<Ty>,
738 ) -> Option<TraitRef> {
739 self.lower_trait_ref_from_path(&trait_ref.path, explicit_self_ty)
742 fn trait_ref_substs_from_path(
744 segment: PathSegment<'_>,
746 explicit_self_ty: Option<Ty>,
748 self.substs_from_path_segment(segment, Some(resolved.into()), false, explicit_self_ty)
751 pub(crate) fn lower_where_predicate(
753 where_predicate: &'a WherePredicate,
754 ignore_bindings: bool,
755 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
756 match where_predicate {
757 WherePredicate::ForLifetime { target, bound, .. }
758 | WherePredicate::TypeBound { target, bound } => {
759 let self_ty = match target {
760 WherePredicateTypeTarget::TypeRef(type_ref) => self.lower_ty(type_ref),
761 WherePredicateTypeTarget::TypeParam(param_id) => {
762 let generic_def = self.resolver.generic_def().expect("generics in scope");
763 let generics = generics(self.db.upcast(), generic_def);
765 hir_def::TypeParamId { parent: generic_def, local_id: *param_id };
766 let placeholder = to_placeholder_idx(self.db, param_id);
767 match self.type_param_mode {
768 TypeParamLoweringMode::Placeholder => TyKind::Placeholder(placeholder),
769 TypeParamLoweringMode::Variable => {
770 let idx = generics.param_idx(param_id).expect("matching generics");
771 TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, idx))
777 self.lower_type_bound(bound, self_ty, ignore_bindings)
781 WherePredicate::Lifetime { .. } => vec![].into_iter(),
785 pub(crate) fn lower_type_bound(
787 bound: &'a TypeBound,
789 ignore_bindings: bool,
790 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
791 let mut bindings = None;
792 let trait_ref = match bound {
793 TypeBound::Path(path, TraitBoundModifier::None) => {
794 bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
795 bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
797 TypeBound::Path(path, TraitBoundModifier::Maybe) => {
798 let sized_trait = self
801 .and_then(|krate| self.db.lang_item(krate, SmolStr::new_inline("sized")))
802 .and_then(|lang_item| lang_item.as_trait());
803 // Don't lower associated type bindings as the only possible relaxed trait bound
804 // `?Sized` has no of them.
805 // If we got another trait here ignore the bound completely.
807 .lower_trait_ref_from_path(path, Some(self_ty.clone()))
808 .map(|trait_ref| trait_ref.hir_trait_id());
809 if trait_id == sized_trait {
810 self.unsized_types.borrow_mut().insert(self_ty);
814 TypeBound::ForLifetime(_, path) => {
815 // FIXME Don't silently drop the hrtb lifetimes here
816 bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
817 bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
819 TypeBound::Lifetime(_) => None,
820 TypeBound::Error => None,
822 trait_ref.into_iter().chain(
825 .filter(move |_| !ignore_bindings)
826 .flat_map(move |tr| self.assoc_type_bindings_from_type_bound(bound, tr)),
830 fn assoc_type_bindings_from_type_bound(
832 bound: &'a TypeBound,
834 ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
835 let last_segment = match bound {
836 TypeBound::Path(path, TraitBoundModifier::None) | TypeBound::ForLifetime(_, path) => {
837 path.segments().last()
839 TypeBound::Path(_, TraitBoundModifier::Maybe)
841 | TypeBound::Lifetime(_) => None,
845 .filter_map(|segment| segment.args_and_bindings)
846 .flat_map(|args_and_bindings| &args_and_bindings.bindings)
847 .flat_map(move |binding| {
848 let found = associated_type_by_name_including_super_traits(
853 let (super_trait_ref, associated_ty) = match found {
854 None => return SmallVec::new(),
857 let projection_ty = ProjectionTy {
858 associated_ty_id: to_assoc_type_id(associated_ty),
859 substitution: super_trait_ref.substitution,
861 let mut preds: SmallVec<[_; 1]> = SmallVec::with_capacity(
862 binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
864 if let Some(type_ref) = &binding.type_ref {
865 let ty = self.lower_ty(type_ref);
867 AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty };
868 preds.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq)));
870 for bound in &binding.bounds {
871 preds.extend(self.lower_type_bound(
873 TyKind::Alias(AliasTy::Projection(projection_ty.clone())).intern(Interner),
883 bounds: &[Interned<TypeBound>],
885 ) -> ReturnTypeImplTrait {
886 cov_mark::hit!(lower_rpit);
887 let self_ty = TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(Interner);
888 let predicates = self.with_shifted_in(DebruijnIndex::ONE, |ctx| {
889 let mut predicates: Vec<_> = bounds
891 .flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false))
894 if !ctx.unsized_types.borrow().contains(&self_ty) {
895 let krate = func.lookup(ctx.db.upcast()).module(ctx.db.upcast()).krate();
896 let sized_trait = ctx
898 .lang_item(krate, SmolStr::new_inline("sized"))
899 .and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id));
900 let sized_clause = sized_trait.map(|trait_id| {
901 let clause = WhereClause::Implemented(TraitRef {
903 substitution: Substitution::from1(Interner, self_ty.clone()),
905 crate::wrap_empty_binders(clause)
907 predicates.extend(sized_clause.into_iter());
908 predicates.shrink_to_fit();
913 ReturnTypeImplTrait { bounds: crate::make_only_type_binders(1, predicates) }
917 fn count_impl_traits(type_ref: &TypeRef) -> usize {
919 type_ref.walk(&mut |type_ref| {
920 if matches!(type_ref, TypeRef::ImplTrait(_)) {
927 /// Build the signature of a callable item (function, struct or enum variant).
928 pub fn callable_item_sig(db: &dyn HirDatabase, def: CallableDefId) -> PolyFnSig {
930 CallableDefId::FunctionId(f) => fn_sig_for_fn(db, f),
931 CallableDefId::StructId(s) => fn_sig_for_struct_constructor(db, s),
932 CallableDefId::EnumVariantId(e) => fn_sig_for_enum_variant_constructor(db, e),
936 pub fn associated_type_shorthand_candidates<R>(
937 db: &dyn HirDatabase,
940 cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>,
942 named_associated_type_shorthand_candidates(db, def, res, None, cb)
945 fn named_associated_type_shorthand_candidates<R>(
946 db: &dyn HirDatabase,
947 // If the type parameter is defined in an impl and we're in a method, there
948 // might be additional where clauses to consider
951 assoc_name: Option<Name>,
952 mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>,
954 let mut search = |t| {
955 for t in all_super_trait_refs(db, t) {
956 let data = db.trait_data(t.hir_trait_id());
958 for (name, assoc_id) in &data.items {
959 if let AssocItemId::TypeAliasId(alias) = assoc_id {
960 if let Some(result) = cb(name, &t, *alias) {
970 TypeNs::SelfType(impl_id) => search(
971 // we're _in_ the impl -- the binders get added back later. Correct,
972 // but it would be nice to make this more explicit
973 db.impl_trait(impl_id)?.into_value_and_skipped_binders().0,
975 TypeNs::GenericParam(param_id) => {
976 let predicates = db.generic_predicates_for_param(def, param_id, assoc_name);
977 let res = predicates.iter().find_map(|pred| match pred.skip_binders().skip_binders() {
978 // FIXME: how to correctly handle higher-ranked bounds here?
979 WhereClause::Implemented(tr) => search(
981 .shifted_out_to(Interner, DebruijnIndex::ONE)
982 .expect("FIXME unexpected higher-ranked trait bound"),
986 if let res @ Some(_) = res {
989 // Handle `Self::Type` referring to own associated type in trait definitions
990 if let GenericDefId::TraitId(trait_id) = param_id.parent {
991 let generics = generics(db.upcast(), trait_id.into());
992 if generics.params.types[param_id.local_id].provenance
993 == TypeParamProvenance::TraitSelf
995 let trait_ref = TyBuilder::trait_ref(db, trait_id)
996 .fill_with_bound_vars(DebruijnIndex::INNERMOST, 0)
998 return search(trait_ref);
1007 /// Build the type of all specific fields of a struct or enum variant.
1008 pub(crate) fn field_types_query(
1009 db: &dyn HirDatabase,
1010 variant_id: VariantId,
1011 ) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>> {
1012 let var_data = variant_id.variant_data(db.upcast());
1013 let (resolver, def): (_, GenericDefId) = match variant_id {
1014 VariantId::StructId(it) => (it.resolver(db.upcast()), it.into()),
1015 VariantId::UnionId(it) => (it.resolver(db.upcast()), it.into()),
1016 VariantId::EnumVariantId(it) => (it.parent.resolver(db.upcast()), it.parent.into()),
1018 let generics = generics(db.upcast(), def);
1019 let mut res = ArenaMap::default();
1021 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1022 for (field_id, field_data) in var_data.fields().iter() {
1023 res.insert(field_id, make_binders(&generics, ctx.lower_ty(&field_data.type_ref)))
1028 /// This query exists only to be used when resolving short-hand associated types
1031 /// See the analogous query in rustc and its comment:
1032 /// <https://github.com/rust-lang/rust/blob/9150f844e2624eb013ec78ca08c1d416e6644026/src/librustc_typeck/astconv.rs#L46>
1033 /// This is a query mostly to handle cycles somewhat gracefully; e.g. the
1034 /// following bounds are disallowed: `T: Foo<U::Item>, U: Foo<T::Item>`, but
1035 /// these are fine: `T: Foo<U::Item>, U: Foo<()>`.
1036 pub(crate) fn generic_predicates_for_param_query(
1037 db: &dyn HirDatabase,
1039 param_id: TypeParamId,
1040 assoc_name: Option<Name>,
1041 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
1042 let resolver = def.resolver(db.upcast());
1044 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1045 let generics = generics(db.upcast(), def);
1046 let mut predicates: Vec<_> = resolver
1047 .where_predicates_in_scope()
1048 // we have to filter out all other predicates *first*, before attempting to lower them
1049 .filter(|pred| match pred {
1050 WherePredicate::ForLifetime { target, bound, .. }
1051 | WherePredicate::TypeBound { target, bound, .. } => {
1053 WherePredicateTypeTarget::TypeRef(type_ref) => {
1054 if ctx.lower_ty_only_param(type_ref) != Some(param_id) {
1058 WherePredicateTypeTarget::TypeParam(local_id) => {
1059 if *local_id != param_id.local_id {
1066 TypeBound::ForLifetime(_, path) | TypeBound::Path(path, _) => {
1067 // Only lower the bound if the trait could possibly define the associated
1068 // type we're looking for.
1070 let assoc_name = match &assoc_name {
1072 None => return true,
1074 let tr = match resolver
1075 .resolve_path_in_type_ns_fully(db.upcast(), path.mod_path())
1077 Some(TypeNs::TraitId(tr)) => tr,
1081 all_super_traits(db.upcast(), tr).iter().any(|tr| {
1082 db.trait_data(*tr).items.iter().any(|(name, item)| {
1083 matches!(item, AssocItemId::TypeAliasId(_)) && name == assoc_name
1087 TypeBound::Lifetime(_) | TypeBound::Error => false,
1090 WherePredicate::Lifetime { .. } => false,
1092 .flat_map(|pred| ctx.lower_where_predicate(pred, true).map(|p| make_binders(&generics, p)))
1095 let subst = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1096 let explicitly_unsized_tys = ctx.unsized_types.into_inner();
1097 let implicitly_sized_predicates =
1098 implicitly_sized_clauses(db, param_id.parent, &explicitly_unsized_tys, &subst, &resolver)
1099 .map(|p| make_binders(&generics, crate::wrap_empty_binders(p)));
1100 predicates.extend(implicitly_sized_predicates);
1104 pub(crate) fn generic_predicates_for_param_recover(
1105 _db: &dyn HirDatabase,
1107 _def: &GenericDefId,
1108 _param_id: &TypeParamId,
1109 _assoc_name: &Option<Name>,
1110 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
1114 pub(crate) fn trait_environment_query(
1115 db: &dyn HirDatabase,
1117 ) -> Arc<TraitEnvironment> {
1118 let resolver = def.resolver(db.upcast());
1119 let ctx = TyLoweringContext::new(db, &resolver)
1120 .with_type_param_mode(TypeParamLoweringMode::Placeholder);
1121 let mut traits_in_scope = Vec::new();
1122 let mut clauses = Vec::new();
1123 for pred in resolver.where_predicates_in_scope() {
1124 for pred in ctx.lower_where_predicate(pred, false) {
1125 if let WhereClause::Implemented(tr) = &pred.skip_binders() {
1126 traits_in_scope.push((tr.self_type_parameter(Interner).clone(), tr.hir_trait_id()));
1128 let program_clause: chalk_ir::ProgramClause<Interner> = pred.cast(Interner);
1129 clauses.push(program_clause.into_from_env_clause(Interner));
1133 let container: Option<ItemContainerId> = match def {
1134 // FIXME: is there a function for this?
1135 GenericDefId::FunctionId(f) => Some(f.lookup(db.upcast()).container),
1136 GenericDefId::AdtId(_) => None,
1137 GenericDefId::TraitId(_) => None,
1138 GenericDefId::TypeAliasId(t) => Some(t.lookup(db.upcast()).container),
1139 GenericDefId::ImplId(_) => None,
1140 GenericDefId::EnumVariantId(_) => None,
1141 GenericDefId::ConstId(c) => Some(c.lookup(db.upcast()).container),
1143 if let Some(ItemContainerId::TraitId(trait_id)) = container {
1144 // add `Self: Trait<T1, T2, ...>` to the environment in trait
1145 // function default implementations (and speculative code
1146 // inside consts or type aliases)
1147 cov_mark::hit!(trait_self_implements_self);
1148 let substs = TyBuilder::type_params_subst(db, trait_id);
1149 let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs };
1150 let pred = WhereClause::Implemented(trait_ref);
1151 let program_clause: chalk_ir::ProgramClause<Interner> = pred.cast(Interner);
1152 clauses.push(program_clause.into_from_env_clause(Interner));
1155 let subst = generics(db.upcast(), def).type_params_subst(db);
1156 let explicitly_unsized_tys = ctx.unsized_types.into_inner();
1157 let implicitly_sized_clauses =
1158 implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver).map(|pred| {
1159 let program_clause: chalk_ir::ProgramClause<Interner> = pred.cast(Interner);
1160 program_clause.into_from_env_clause(Interner)
1162 clauses.extend(implicitly_sized_clauses);
1164 let krate = def.module(db.upcast()).krate();
1166 let env = chalk_ir::Environment::new(Interner).add_clauses(Interner, clauses);
1168 Arc::new(TraitEnvironment { krate, traits_from_clauses: traits_in_scope, env })
1171 /// Resolve the where clause(s) of an item with generics.
1172 pub(crate) fn generic_predicates_query(
1173 db: &dyn HirDatabase,
1175 ) -> Arc<[Binders<QuantifiedWhereClause>]> {
1176 let resolver = def.resolver(db.upcast());
1178 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1179 let generics = generics(db.upcast(), def);
1181 let mut predicates = resolver
1182 .where_predicates_in_scope()
1183 .flat_map(|pred| ctx.lower_where_predicate(pred, false).map(|p| make_binders(&generics, p)))
1184 .collect::<Vec<_>>();
1186 let subst = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1187 let explicitly_unsized_tys = ctx.unsized_types.into_inner();
1188 let implicitly_sized_predicates =
1189 implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver)
1190 .map(|p| make_binders(&generics, crate::wrap_empty_binders(p)));
1191 predicates.extend(implicitly_sized_predicates);
1195 /// Generate implicit `: Sized` predicates for all generics that has no `?Sized` bound.
1196 /// Exception is Self of a trait def.
1197 fn implicitly_sized_clauses<'a>(
1198 db: &dyn HirDatabase,
1200 explicitly_unsized_tys: &'a FxHashSet<Ty>,
1201 substitution: &'a Substitution,
1202 resolver: &Resolver,
1203 ) -> impl Iterator<Item = WhereClause> + 'a {
1204 let is_trait_def = matches!(def, GenericDefId::TraitId(..));
1205 let generic_args = &substitution.as_slice(Interner)[is_trait_def as usize..];
1206 let sized_trait = resolver
1208 .and_then(|krate| db.lang_item(krate, SmolStr::new_inline("sized")))
1209 .and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id));
1211 sized_trait.into_iter().flat_map(move |sized_trait| {
1212 let implicitly_sized_tys = generic_args
1214 .filter_map(|generic_arg| generic_arg.ty(Interner))
1215 .filter(move |&self_ty| !explicitly_unsized_tys.contains(self_ty));
1216 implicitly_sized_tys.map(move |self_ty| {
1217 WhereClause::Implemented(TraitRef {
1218 trait_id: sized_trait,
1219 substitution: Substitution::from1(Interner, self_ty.clone()),
1225 /// Resolve the default type params from generics
1226 pub(crate) fn generic_defaults_query(
1227 db: &dyn HirDatabase,
1229 ) -> Arc<[Binders<Ty>]> {
1230 let resolver = def.resolver(db.upcast());
1232 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1233 let generic_params = generics(db.upcast(), def);
1235 let defaults = generic_params
1238 .map(|(idx, (_, p))| {
1240 p.default.as_ref().map_or(TyKind::Error.intern(Interner), |t| ctx.lower_ty(t));
1242 // Each default can only refer to previous parameters.
1243 ty = crate::fold_free_vars(ty, |bound, binders| {
1244 if bound.index >= idx && bound.debruijn == DebruijnIndex::INNERMOST {
1245 // type variable default referring to parameter coming
1246 // after it. This is forbidden (FIXME: report
1248 TyKind::Error.intern(Interner)
1250 bound.shifted_in_from(binders).to_ty(Interner)
1254 crate::make_only_type_binders(idx, ty)
1261 pub(crate) fn generic_defaults_recover(
1262 db: &dyn HirDatabase,
1265 ) -> Arc<[Binders<Ty>]> {
1266 let generic_params = generics(db.upcast(), *def);
1268 // we still need one default per parameter
1269 let defaults = generic_params
1273 let ty = TyKind::Error.intern(Interner);
1275 crate::make_only_type_binders(idx, ty)
1282 fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
1283 let data = db.function_data(def);
1284 let resolver = def.resolver(db.upcast());
1285 let ctx_params = TyLoweringContext::new(db, &resolver)
1286 .with_impl_trait_mode(ImplTraitLoweringMode::Variable)
1287 .with_type_param_mode(TypeParamLoweringMode::Variable);
1288 let params = data.params.iter().map(|(_, tr)| ctx_params.lower_ty(tr)).collect::<Vec<_>>();
1289 let ctx_ret = TyLoweringContext::new(db, &resolver)
1290 .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
1291 .with_type_param_mode(TypeParamLoweringMode::Variable);
1292 let ret = ctx_ret.lower_ty(&data.ret_type);
1293 let generics = generics(db.upcast(), def.into());
1294 let mut sig = CallableSig::from_params_and_return(params, ret, data.is_varargs());
1295 if !data.legacy_const_generics_indices.is_empty() {
1296 sig.set_legacy_const_generics_indices(&data.legacy_const_generics_indices);
1298 make_binders(&generics, sig)
1301 /// Build the declared type of a function. This should not need to look at the
1303 fn type_for_fn(db: &dyn HirDatabase, def: FunctionId) -> Binders<Ty> {
1304 let generics = generics(db.upcast(), def.into());
1305 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1308 TyKind::FnDef(CallableDefId::FunctionId(def).to_chalk(db), substs).intern(Interner),
1312 /// Build the declared type of a const.
1313 fn type_for_const(db: &dyn HirDatabase, def: ConstId) -> Binders<Ty> {
1314 let data = db.const_data(def);
1315 let generics = generics(db.upcast(), def.into());
1316 let resolver = def.resolver(db.upcast());
1318 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1320 make_binders(&generics, ctx.lower_ty(&data.type_ref))
1323 /// Build the declared type of a static.
1324 fn type_for_static(db: &dyn HirDatabase, def: StaticId) -> Binders<Ty> {
1325 let data = db.static_data(def);
1326 let resolver = def.resolver(db.upcast());
1327 let ctx = TyLoweringContext::new(db, &resolver);
1329 Binders::empty(Interner, ctx.lower_ty(&data.type_ref))
1332 fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnSig {
1333 let struct_data = db.struct_data(def);
1334 let fields = struct_data.variant_data.fields();
1335 let resolver = def.resolver(db.upcast());
1337 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1338 let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
1339 let (ret, binders) = type_for_adt(db, def.into()).into_value_and_skipped_binders();
1340 Binders::new(binders, CallableSig::from_params_and_return(params, ret, false))
1343 /// Build the type of a tuple struct constructor.
1344 fn type_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> Binders<Ty> {
1345 let struct_data = db.struct_data(def);
1346 if let StructKind::Unit = struct_data.variant_data.kind() {
1347 return type_for_adt(db, def.into());
1349 let generics = generics(db.upcast(), def.into());
1350 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1353 TyKind::FnDef(CallableDefId::StructId(def).to_chalk(db), substs).intern(Interner),
1357 fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> PolyFnSig {
1358 let enum_data = db.enum_data(def.parent);
1359 let var_data = &enum_data.variants[def.local_id];
1360 let fields = var_data.variant_data.fields();
1361 let resolver = def.parent.resolver(db.upcast());
1363 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1364 let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::<Vec<_>>();
1365 let (ret, binders) = type_for_adt(db, def.parent.into()).into_value_and_skipped_binders();
1366 Binders::new(binders, CallableSig::from_params_and_return(params, ret, false))
1369 /// Build the type of a tuple enum variant constructor.
1370 fn type_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> Binders<Ty> {
1371 let enum_data = db.enum_data(def.parent);
1372 let var_data = &enum_data.variants[def.local_id].variant_data;
1373 if let StructKind::Unit = var_data.kind() {
1374 return type_for_adt(db, def.parent.into());
1376 let generics = generics(db.upcast(), def.parent.into());
1377 let substs = generics.bound_vars_subst(DebruijnIndex::INNERMOST);
1380 TyKind::FnDef(CallableDefId::EnumVariantId(def).to_chalk(db), substs).intern(Interner),
1384 fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
1385 let generics = generics(db.upcast(), adt.into());
1386 let b = TyBuilder::adt(db, adt);
1387 let ty = b.fill_with_bound_vars(DebruijnIndex::INNERMOST, 0).build();
1388 make_binders(&generics, ty)
1391 fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
1392 let generics = generics(db.upcast(), t.into());
1393 let resolver = t.resolver(db.upcast());
1395 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1396 if db.type_alias_data(t).is_extern {
1397 Binders::empty(Interner, TyKind::Foreign(crate::to_foreign_def_id(t)).intern(Interner))
1399 let type_ref = &db.type_alias_data(t).type_ref;
1400 let inner = ctx.lower_ty(type_ref.as_deref().unwrap_or(&TypeRef::Error));
1401 make_binders(&generics, inner)
1405 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
1406 pub enum CallableDefId {
1407 FunctionId(FunctionId),
1409 EnumVariantId(EnumVariantId),
1411 impl_from!(FunctionId, StructId, EnumVariantId for CallableDefId);
1413 impl CallableDefId {
1414 pub fn krate(self, db: &dyn HirDatabase) -> CrateId {
1415 let db = db.upcast();
1417 CallableDefId::FunctionId(f) => f.lookup(db).module(db),
1418 CallableDefId::StructId(s) => s.lookup(db).container,
1419 CallableDefId::EnumVariantId(e) => e.parent.lookup(db).container,
1425 impl From<CallableDefId> for GenericDefId {
1426 fn from(def: CallableDefId) -> GenericDefId {
1428 CallableDefId::FunctionId(f) => f.into(),
1429 CallableDefId::StructId(s) => s.into(),
1430 CallableDefId::EnumVariantId(e) => e.into(),
1435 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1437 BuiltinType(BuiltinType),
1439 TypeAliasId(TypeAliasId),
1441 impl_from!(BuiltinType, AdtId(StructId, EnumId, UnionId), TypeAliasId for TyDefId);
1443 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1444 pub enum ValueTyDefId {
1445 FunctionId(FunctionId),
1448 EnumVariantId(EnumVariantId),
1452 impl_from!(FunctionId, StructId, UnionId, EnumVariantId, ConstId, StaticId for ValueTyDefId);
1454 /// Build the declared type of an item. This depends on the namespace; e.g. for
1455 /// `struct Foo(usize)`, we have two types: The type of the struct itself, and
1456 /// the constructor function `(usize) -> Foo` which lives in the values
1458 pub(crate) fn ty_query(db: &dyn HirDatabase, def: TyDefId) -> Binders<Ty> {
1460 TyDefId::BuiltinType(it) => Binders::empty(Interner, TyBuilder::builtin(it)),
1461 TyDefId::AdtId(it) => type_for_adt(db, it),
1462 TyDefId::TypeAliasId(it) => type_for_type_alias(db, it),
1466 pub(crate) fn ty_recover(db: &dyn HirDatabase, _cycle: &[String], def: &TyDefId) -> Binders<Ty> {
1467 let generics = match *def {
1468 TyDefId::BuiltinType(_) => return Binders::empty(Interner, TyKind::Error.intern(Interner)),
1469 TyDefId::AdtId(it) => generics(db.upcast(), it.into()),
1470 TyDefId::TypeAliasId(it) => generics(db.upcast(), it.into()),
1472 make_binders(&generics, TyKind::Error.intern(Interner))
1475 pub(crate) fn value_ty_query(db: &dyn HirDatabase, def: ValueTyDefId) -> Binders<Ty> {
1477 ValueTyDefId::FunctionId(it) => type_for_fn(db, it),
1478 ValueTyDefId::StructId(it) => type_for_struct_constructor(db, it),
1479 ValueTyDefId::UnionId(it) => type_for_adt(db, it.into()),
1480 ValueTyDefId::EnumVariantId(it) => type_for_enum_variant_constructor(db, it),
1481 ValueTyDefId::ConstId(it) => type_for_const(db, it),
1482 ValueTyDefId::StaticId(it) => type_for_static(db, it),
1486 pub(crate) fn impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binders<Ty> {
1487 let impl_loc = impl_id.lookup(db.upcast());
1488 let impl_data = db.impl_data(impl_id);
1489 let resolver = impl_id.resolver(db.upcast());
1490 let _cx = stdx::panic_context::enter(format!(
1491 "impl_self_ty_query({:?} -> {:?} -> {:?})",
1492 impl_id, impl_loc, impl_data
1494 let generics = generics(db.upcast(), impl_id.into());
1496 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1497 make_binders(&generics, ctx.lower_ty(&impl_data.self_ty))
1500 pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
1501 let parent_data = db.generic_params(def.parent);
1502 let data = &parent_data.consts[def.local_id];
1503 let resolver = def.parent.resolver(db.upcast());
1504 let ctx = TyLoweringContext::new(db, &resolver);
1506 ctx.lower_ty(&data.ty)
1509 pub(crate) fn impl_self_ty_recover(
1510 db: &dyn HirDatabase,
1514 let generics = generics(db.upcast(), (*impl_id).into());
1515 make_binders(&generics, TyKind::Error.intern(Interner))
1518 pub(crate) fn impl_trait_query(db: &dyn HirDatabase, impl_id: ImplId) -> Option<Binders<TraitRef>> {
1519 let impl_loc = impl_id.lookup(db.upcast());
1520 let impl_data = db.impl_data(impl_id);
1521 let resolver = impl_id.resolver(db.upcast());
1522 let _cx = stdx::panic_context::enter(format!(
1523 "impl_trait_query({:?} -> {:?} -> {:?})",
1524 impl_id, impl_loc, impl_data
1527 TyLoweringContext::new(db, &resolver).with_type_param_mode(TypeParamLoweringMode::Variable);
1528 let (self_ty, binders) = db.impl_self_ty(impl_id).into_value_and_skipped_binders();
1529 let target_trait = impl_data.target_trait.as_ref()?;
1530 Some(Binders::new(binders, ctx.lower_trait_ref(target_trait, Some(self_ty))?))
1533 pub(crate) fn return_type_impl_traits(
1534 db: &dyn HirDatabase,
1535 def: hir_def::FunctionId,
1536 ) -> Option<Arc<Binders<ReturnTypeImplTraits>>> {
1537 // FIXME unify with fn_sig_for_fn instead of doing lowering twice, maybe
1538 let data = db.function_data(def);
1539 let resolver = def.resolver(db.upcast());
1540 let ctx_ret = TyLoweringContext::new(db, &resolver)
1541 .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
1542 .with_type_param_mode(TypeParamLoweringMode::Variable);
1543 let _ret = (&ctx_ret).lower_ty(&data.ret_type);
1544 let generics = generics(db.upcast(), def.into());
1545 let return_type_impl_traits =
1546 ReturnTypeImplTraits { impl_traits: ctx_ret.opaque_type_data.into_inner() };
1547 if return_type_impl_traits.impl_traits.is_empty() {
1550 Some(Arc::new(make_binders(&generics, return_type_impl_traits)))
1554 pub(crate) fn lower_to_chalk_mutability(m: hir_def::type_ref::Mutability) -> Mutability {
1556 hir_def::type_ref::Mutability::Shared => Mutability::Not,
1557 hir_def::type_ref::Mutability::Mut => Mutability::Mut,
1561 fn make_binders<T: HasInterner<Interner = Interner>>(generics: &Generics, value: T) -> Binders<T> {
1562 crate::make_only_type_binders(generics.len(), value)