//! Methods for lowering the HIR to types. There are two main cases here: //! //! - Lowering a type reference like `&usize` or `Option` to a //! type: The entry point for this is `TyLoweringContext::lower_ty`. //! - Building the type for an item: This happens through the `ty` query. //! //! This usually involves resolving names, collecting generic arguments etc. use std::{ cell::{Cell, RefCell, RefMut}, iter, sync::Arc, }; use base_db::CrateId; use chalk_ir::{ cast::Cast, fold::Shift, fold::TypeFoldable, interner::HasInterner, Mutability, Safety, }; use either::Either; use hir_def::{ adt::StructKind, body::{Expander, LowerCtx}, builtin_type::BuiltinType, generics::{ TypeOrConstParamData, TypeParamProvenance, WherePredicate, WherePredicateTypeTarget, }, lang_item::{lang_attr, LangItem}, path::{GenericArg, GenericArgs, ModPath, Path, PathKind, PathSegment, PathSegments}, resolver::{HasResolver, Resolver, TypeNs}, type_ref::{ConstRefOrPath, TraitBoundModifier, TraitRef as HirTraitRef, TypeBound, TypeRef}, AdtId, AssocItemId, ConstId, ConstParamId, DefWithBodyId, EnumId, EnumVariantId, FunctionId, GenericDefId, HasModule, ImplId, ItemContainerId, LocalFieldId, Lookup, ModuleDefId, StaticId, StructId, TraitId, TypeAliasId, TypeOrConstParamId, TypeParamId, UnionId, VariantId, }; use hir_expand::{name::Name, ExpandResult}; use intern::Interned; use la_arena::{Arena, ArenaMap}; use rustc_hash::FxHashSet; use smallvec::SmallVec; use stdx::{impl_from, never}; use syntax::ast; use crate::{ all_super_traits, consteval::{intern_const_ref, path_to_const, unknown_const, unknown_const_as_generic}, db::HirDatabase, make_binders, mapping::{from_chalk_trait_id, ToChalk}, static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx, utils::Generics, utils::{all_super_trait_refs, associated_type_by_name_including_super_traits, generics}, AliasEq, AliasTy, Binders, BoundVar, CallableSig, Const, DebruijnIndex, DynTy, FnPointer, FnSig, FnSubst, GenericArgData, ImplTraitId, Interner, ParamKind, PolyFnSig, ProjectionTy, QuantifiedWhereClause, QuantifiedWhereClauses, ReturnTypeImplTrait, ReturnTypeImplTraits, Substitution, TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyKind, WhereClause, }; #[derive(Debug)] enum ImplTraitLoweringState { /// When turning `impl Trait` into opaque types, we have to collect the /// bounds at the same time to get the IDs correct (without becoming too /// complicated). I don't like using interior mutability (as for the /// counter), but I've tried and failed to make the lifetimes work for /// passing around a `&mut TyLoweringContext`. The core problem is that /// we're grouping the mutable data (the counter and this field) together /// with the immutable context (the references to the DB and resolver). /// Splitting this up would be a possible fix. Opaque(RefCell>), Param(Cell), Variable(Cell), Disallowed, } impl ImplTraitLoweringState { fn new(impl_trait_mode: ImplTraitLoweringMode) -> ImplTraitLoweringState { match impl_trait_mode { ImplTraitLoweringMode::Opaque => Self::Opaque(RefCell::new(Arena::new())), ImplTraitLoweringMode::Param => Self::Param(Cell::new(0)), ImplTraitLoweringMode::Variable => Self::Variable(Cell::new(0)), ImplTraitLoweringMode::Disallowed => Self::Disallowed, } } fn take(&self) -> Self { match self { Self::Opaque(x) => Self::Opaque(RefCell::new(x.take())), Self::Param(x) => Self::Param(Cell::new(x.get())), Self::Variable(x) => Self::Variable(Cell::new(x.get())), Self::Disallowed => Self::Disallowed, } } fn swap(&self, impl_trait_mode: &Self) { match (self, impl_trait_mode) { (Self::Opaque(x), Self::Opaque(y)) => x.swap(y), (Self::Param(x), Self::Param(y)) => x.swap(y), (Self::Variable(x), Self::Variable(y)) => x.swap(y), (Self::Disallowed, Self::Disallowed) => (), _ => panic!("mismatched lowering mode"), } } } #[derive(Debug)] pub struct TyLoweringContext<'a> { pub db: &'a dyn HirDatabase, resolver: &'a Resolver, in_binders: DebruijnIndex, /// Note: Conceptually, it's thinkable that we could be in a location where /// some type params should be represented as placeholders, and others /// should be converted to variables. I think in practice, this isn't /// possible currently, so this should be fine for now. pub type_param_mode: ParamLoweringMode, impl_trait_mode: ImplTraitLoweringState, expander: RefCell>, /// Tracks types with explicit `?Sized` bounds. pub(crate) unsized_types: RefCell>, } impl<'a> TyLoweringContext<'a> { pub fn new(db: &'a dyn HirDatabase, resolver: &'a Resolver) -> Self { let impl_trait_mode = ImplTraitLoweringState::Disallowed; let type_param_mode = ParamLoweringMode::Placeholder; let in_binders = DebruijnIndex::INNERMOST; Self { db, resolver, in_binders, impl_trait_mode, type_param_mode, expander: RefCell::new(None), unsized_types: RefCell::default(), } } pub fn with_debruijn( &self, debruijn: DebruijnIndex, f: impl FnOnce(&TyLoweringContext<'_>) -> T, ) -> T { let impl_trait_mode = self.impl_trait_mode.take(); let expander = self.expander.take(); let unsized_types = self.unsized_types.take(); let new_ctx = Self { in_binders: debruijn, impl_trait_mode, expander: RefCell::new(expander), unsized_types: RefCell::new(unsized_types), ..*self }; let result = f(&new_ctx); self.impl_trait_mode.swap(&new_ctx.impl_trait_mode); self.expander.replace(new_ctx.expander.into_inner()); self.unsized_types.replace(new_ctx.unsized_types.into_inner()); result } pub fn with_shifted_in( &self, debruijn: DebruijnIndex, f: impl FnOnce(&TyLoweringContext<'_>) -> T, ) -> T { self.with_debruijn(self.in_binders.shifted_in_from(debruijn), f) } pub fn with_impl_trait_mode(self, impl_trait_mode: ImplTraitLoweringMode) -> Self { Self { impl_trait_mode: ImplTraitLoweringState::new(impl_trait_mode), ..self } } pub fn with_type_param_mode(self, type_param_mode: ParamLoweringMode) -> Self { Self { type_param_mode, ..self } } } #[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum ImplTraitLoweringMode { /// `impl Trait` gets lowered into an opaque type that doesn't unify with /// anything except itself. This is used in places where values flow 'out', /// i.e. for arguments of the function we're currently checking, and return /// types of functions we're calling. Opaque, /// `impl Trait` gets lowered into a type variable. Used for argument /// position impl Trait when inside the respective function, since it allows /// us to support that without Chalk. Param, /// `impl Trait` gets lowered into a variable that can unify with some /// type. This is used in places where values flow 'in', i.e. for arguments /// of functions we're calling, and the return type of the function we're /// currently checking. Variable, /// `impl Trait` is disallowed and will be an error. Disallowed, } #[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum ParamLoweringMode { Placeholder, Variable, } impl<'a> TyLoweringContext<'a> { pub fn lower_ty(&self, type_ref: &TypeRef) -> Ty { self.lower_ty_ext(type_ref).0 } fn generics(&self) -> Generics { generics( self.db.upcast(), self.resolver .generic_def() .expect("there should be generics if there's a generic param"), ) } pub fn lower_ty_ext(&self, type_ref: &TypeRef) -> (Ty, Option) { let mut res = None; let ty = match type_ref { TypeRef::Never => TyKind::Never.intern(Interner), TypeRef::Tuple(inner) => { let inner_tys = inner.iter().map(|tr| self.lower_ty(tr)); TyKind::Tuple(inner_tys.len(), Substitution::from_iter(Interner, inner_tys)) .intern(Interner) } TypeRef::Path(path) => { let (ty, res_) = self.lower_path(path); res = res_; ty } TypeRef::RawPtr(inner, mutability) => { let inner_ty = self.lower_ty(inner); TyKind::Raw(lower_to_chalk_mutability(*mutability), inner_ty).intern(Interner) } TypeRef::Array(inner, len) => { let inner_ty = self.lower_ty(inner); let const_len = const_or_path_to_chalk( self.db, self.resolver, TyBuilder::usize(), len, self.type_param_mode, || self.generics(), self.in_binders, ); TyKind::Array(inner_ty, const_len).intern(Interner) } TypeRef::Slice(inner) => { let inner_ty = self.lower_ty(inner); TyKind::Slice(inner_ty).intern(Interner) } TypeRef::Reference(inner, _, mutability) => { let inner_ty = self.lower_ty(inner); let lifetime = static_lifetime(); TyKind::Ref(lower_to_chalk_mutability(*mutability), lifetime, inner_ty) .intern(Interner) } TypeRef::Placeholder => TyKind::Error.intern(Interner), &TypeRef::Fn(ref params, variadic, is_unsafe) => { let substs = self.with_shifted_in(DebruijnIndex::ONE, |ctx| { Substitution::from_iter(Interner, params.iter().map(|(_, tr)| ctx.lower_ty(tr))) }); TyKind::Function(FnPointer { num_binders: 0, // FIXME lower `for<'a> fn()` correctly sig: FnSig { abi: (), safety: if is_unsafe { Safety::Unsafe } else { Safety::Safe }, variadic, }, substitution: FnSubst(substs), }) .intern(Interner) } TypeRef::DynTrait(bounds) => self.lower_dyn_trait(bounds), TypeRef::ImplTrait(bounds) => { match &self.impl_trait_mode { ImplTraitLoweringState::Opaque(opaque_type_data) => { let func = match self.resolver.generic_def() { Some(GenericDefId::FunctionId(f)) => f, _ => panic!("opaque impl trait lowering in non-function"), }; // this dance is to make sure the data is in the right // place even if we encounter more opaque types while // lowering the bounds let idx = opaque_type_data.borrow_mut().alloc(ReturnTypeImplTrait { bounds: crate::make_single_type_binders(Vec::new()), }); // We don't want to lower the bounds inside the binders // we're currently in, because they don't end up inside // those binders. E.g. when we have `impl Trait>`, the `impl OtherTrait` can't refer // to the self parameter from `impl Trait`, and the // bounds aren't actually stored nested within each // other, but separately. So if the `T` refers to a type // parameter of the outer function, it's just one binder // away instead of two. let actual_opaque_type_data = self .with_debruijn(DebruijnIndex::INNERMOST, |ctx| { ctx.lower_impl_trait(bounds, func) }); opaque_type_data.borrow_mut()[idx] = actual_opaque_type_data; let impl_trait_id = ImplTraitId::ReturnTypeImplTrait(func, idx); let opaque_ty_id = self.db.intern_impl_trait_id(impl_trait_id).into(); let generics = generics(self.db.upcast(), func.into()); let parameters = generics.bound_vars_subst(self.db, self.in_binders); TyKind::OpaqueType(opaque_ty_id, parameters).intern(Interner) } ImplTraitLoweringState::Param(counter) => { let idx = counter.get(); // FIXME we're probably doing something wrong here counter.set(idx + count_impl_traits(type_ref) as u16); if let Some(def) = self.resolver.generic_def() { let generics = generics(self.db.upcast(), def); let param = generics .iter() .filter(|(_, data)| { matches!( data, TypeOrConstParamData::TypeParamData(data) if data.provenance == TypeParamProvenance::ArgumentImplTrait ) }) .nth(idx as usize) .map_or(TyKind::Error, |(id, _)| { TyKind::Placeholder(to_placeholder_idx(self.db, id)) }); param.intern(Interner) } else { TyKind::Error.intern(Interner) } } ImplTraitLoweringState::Variable(counter) => { let idx = counter.get(); // FIXME we're probably doing something wrong here counter.set(idx + count_impl_traits(type_ref) as u16); let ( _parent_params, self_params, list_params, const_params, _impl_trait_params, ) = if let Some(def) = self.resolver.generic_def() { let generics = generics(self.db.upcast(), def); generics.provenance_split() } else { (0, 0, 0, 0, 0) }; TyKind::BoundVar(BoundVar::new( self.in_binders, idx as usize + self_params + list_params + const_params, )) .intern(Interner) } ImplTraitLoweringState::Disallowed => { // FIXME: report error TyKind::Error.intern(Interner) } } } TypeRef::Macro(macro_call) => { let (mut expander, recursion_start) = { match RefMut::filter_map(self.expander.borrow_mut(), Option::as_mut) { // There already is an expander here, this means we are already recursing Ok(expander) => (expander, false), // No expander was created yet, so we are at the start of the expansion recursion // and therefore have to create an expander. Err(expander) => ( RefMut::map(expander, |it| { it.insert(Expander::new( self.db.upcast(), macro_call.file_id, self.resolver.module(), )) }), true, ), } }; let ty = { let macro_call = macro_call.to_node(self.db.upcast()); match expander.enter_expand::(self.db.upcast(), macro_call) { Ok(ExpandResult { value: Some((mark, expanded)), .. }) => { let ctx = LowerCtx::new(self.db.upcast(), expander.current_file_id()); let type_ref = TypeRef::from_ast(&ctx, expanded); drop(expander); let ty = self.lower_ty(&type_ref); self.expander .borrow_mut() .as_mut() .unwrap() .exit(self.db.upcast(), mark); Some(ty) } _ => { drop(expander); None } } }; // drop the expander, resetting it to pre-recursion state if recursion_start { *self.expander.borrow_mut() = None; } ty.unwrap_or_else(|| TyKind::Error.intern(Interner)) } TypeRef::Error => TyKind::Error.intern(Interner), }; (ty, res) } /// This is only for `generic_predicates_for_param`, where we can't just /// lower the self types of the predicates since that could lead to cycles. /// So we just check here if the `type_ref` resolves to a generic param, and which. fn lower_ty_only_param(&self, type_ref: &TypeRef) -> Option { let path = match type_ref { TypeRef::Path(path) => path, _ => return None, }; if path.type_anchor().is_some() { return None; } if path.segments().len() > 1 { return None; } let resolution = match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path) { Some((it, None)) => it, _ => return None, }; match resolution { TypeNs::GenericParam(param_id) => Some(param_id.into()), _ => None, } } pub(crate) fn lower_ty_relative_path( &self, ty: Ty, // We need the original resolution to lower `Self::AssocTy` correctly res: Option, remaining_segments: PathSegments<'_>, ) -> (Ty, Option) { match remaining_segments.len() { 0 => (ty, res), 1 => { // resolve unselected assoc types let segment = remaining_segments.first().unwrap(); (self.select_associated_type(res, segment), None) } _ => { // FIXME report error (ambiguous associated type) (TyKind::Error.intern(Interner), None) } } } pub(crate) fn lower_partly_resolved_path( &self, resolution: TypeNs, resolved_segment: PathSegment<'_>, remaining_segments: PathSegments<'_>, infer_args: bool, ) -> (Ty, Option) { let ty = match resolution { TypeNs::TraitId(trait_) => { let ty = match remaining_segments.len() { 1 => { let trait_ref = self.lower_trait_ref_from_resolved_path(trait_, resolved_segment, None); let segment = remaining_segments.first().unwrap(); let found = self .db .trait_data(trait_ref.hir_trait_id()) .associated_type_by_name(segment.name); match found { Some(associated_ty) => { // FIXME: `substs_from_path_segment()` pushes `TyKind::Error` for every parent // generic params. It's inefficient to splice the `Substitution`s, so we may want // that method to optionally take parent `Substitution` as we already know them at // this point (`trait_ref.substitution`). let substitution = self.substs_from_path_segment( segment, Some(associated_ty.into()), false, None, ); let len_self = generics(self.db.upcast(), associated_ty.into()).len_self(); let substitution = Substitution::from_iter( Interner, substitution .iter(Interner) .take(len_self) .chain(trait_ref.substitution.iter(Interner)), ); TyKind::Alias(AliasTy::Projection(ProjectionTy { associated_ty_id: to_assoc_type_id(associated_ty), substitution, })) .intern(Interner) } None => { // FIXME: report error (associated type not found) TyKind::Error.intern(Interner) } } } 0 => { // Trait object type without dyn; this should be handled in upstream. See // `lower_path()`. stdx::never!("unexpected fully resolved trait path"); TyKind::Error.intern(Interner) } _ => { // FIXME report error (ambiguous associated type) TyKind::Error.intern(Interner) } }; return (ty, None); } TypeNs::TraitAliasId(_) => { // FIXME(trait_alias): Implement trait alias. return (TyKind::Error.intern(Interner), None); } TypeNs::GenericParam(param_id) => { let generics = generics( self.db.upcast(), self.resolver.generic_def().expect("generics in scope"), ); match self.type_param_mode { ParamLoweringMode::Placeholder => { TyKind::Placeholder(to_placeholder_idx(self.db, param_id.into())) } ParamLoweringMode::Variable => { let idx = match generics.param_idx(param_id.into()) { None => { never!("no matching generics"); return (TyKind::Error.intern(Interner), None); } Some(idx) => idx, }; TyKind::BoundVar(BoundVar::new(self.in_binders, idx)) } } .intern(Interner) } TypeNs::SelfType(impl_id) => { let def = self.resolver.generic_def().expect("impl should have generic param scope"); let generics = generics(self.db.upcast(), def); match self.type_param_mode { ParamLoweringMode::Placeholder => { // `def` can be either impl itself or item within, and we need impl itself // now. let generics = generics.parent_generics().unwrap_or(&generics); let subst = generics.placeholder_subst(self.db); self.db.impl_self_ty(impl_id).substitute(Interner, &subst) } ParamLoweringMode::Variable => { let starting_from = match def { GenericDefId::ImplId(_) => 0, // `def` is an item within impl. We need to substitute `BoundVar`s but // remember that they are for parent (i.e. impl) generic params so they // come after our own params. _ => generics.len_self(), }; TyBuilder::impl_self_ty(self.db, impl_id) .fill_with_bound_vars(self.in_binders, starting_from) .build() } } } TypeNs::AdtSelfType(adt) => { let generics = generics(self.db.upcast(), adt.into()); let substs = match self.type_param_mode { ParamLoweringMode::Placeholder => generics.placeholder_subst(self.db), ParamLoweringMode::Variable => { generics.bound_vars_subst(self.db, self.in_binders) } }; self.db.ty(adt.into()).substitute(Interner, &substs) } TypeNs::AdtId(it) => self.lower_path_inner(resolved_segment, it.into(), infer_args), TypeNs::BuiltinType(it) => { self.lower_path_inner(resolved_segment, it.into(), infer_args) } TypeNs::TypeAliasId(it) => { self.lower_path_inner(resolved_segment, it.into(), infer_args) } // FIXME: report error TypeNs::EnumVariantId(_) => return (TyKind::Error.intern(Interner), None), }; self.lower_ty_relative_path(ty, Some(resolution), remaining_segments) } pub(crate) fn lower_path(&self, path: &Path) -> (Ty, Option) { // Resolve the path (in type namespace) if let Some(type_ref) = path.type_anchor() { let (ty, res) = self.lower_ty_ext(type_ref); return self.lower_ty_relative_path(ty, res, path.segments()); } let (resolution, remaining_index) = match self.resolver.resolve_path_in_type_ns(self.db.upcast(), path) { Some(it) => it, None => return (TyKind::Error.intern(Interner), None), }; if matches!(resolution, TypeNs::TraitId(_)) && remaining_index.is_none() { // trait object type without dyn let bound = TypeBound::Path(path.clone(), TraitBoundModifier::None); let ty = self.lower_dyn_trait(&[Interned::new(bound)]); return (ty, None); } let (resolved_segment, remaining_segments) = match remaining_index { None => ( path.segments().last().expect("resolved path has at least one element"), PathSegments::EMPTY, ), Some(i) => (path.segments().get(i - 1).unwrap(), path.segments().skip(i)), }; self.lower_partly_resolved_path(resolution, resolved_segment, remaining_segments, false) } fn select_associated_type(&self, res: Option, segment: PathSegment<'_>) -> Ty { let Some((def, res)) = self.resolver.generic_def().zip(res) else { return TyKind::Error.intern(Interner); }; let ty = named_associated_type_shorthand_candidates( self.db, def, res, Some(segment.name.clone()), move |name, t, associated_ty| { if name != segment.name { return None; } let parent_subst = t.substitution.clone(); let parent_subst = match self.type_param_mode { ParamLoweringMode::Placeholder => { // if we're lowering to placeholders, we have to put them in now. let generics = generics(self.db.upcast(), def); let s = generics.placeholder_subst(self.db); s.apply(parent_subst, Interner) } ParamLoweringMode::Variable => { // We need to shift in the bound vars, since // `named_associated_type_shorthand_candidates` does not do that. parent_subst.shifted_in_from(Interner, self.in_binders) } }; // FIXME: `substs_from_path_segment()` pushes `TyKind::Error` for every parent // generic params. It's inefficient to splice the `Substitution`s, so we may want // that method to optionally take parent `Substitution` as we already know them at // this point (`t.substitution`). let substs = self.substs_from_path_segment( segment.clone(), Some(associated_ty.into()), false, None, ); let len_self = generics(self.db.upcast(), associated_ty.into()).len_self(); let substs = Substitution::from_iter( Interner, substs.iter(Interner).take(len_self).chain(parent_subst.iter(Interner)), ); Some( TyKind::Alias(AliasTy::Projection(ProjectionTy { associated_ty_id: to_assoc_type_id(associated_ty), substitution: substs, })) .intern(Interner), ) }, ); ty.unwrap_or_else(|| TyKind::Error.intern(Interner)) } fn lower_path_inner( &self, segment: PathSegment<'_>, typeable: TyDefId, infer_args: bool, ) -> Ty { let generic_def = match typeable { TyDefId::BuiltinType(_) => None, TyDefId::AdtId(it) => Some(it.into()), TyDefId::TypeAliasId(it) => Some(it.into()), }; let substs = self.substs_from_path_segment(segment, generic_def, infer_args, None); self.db.ty(typeable).substitute(Interner, &substs) } /// Collect generic arguments from a path into a `Substs`. See also /// `create_substs_for_ast_path` and `def_to_ty` in rustc. pub(super) fn substs_from_path( &self, path: &Path, // Note that we don't call `db.value_type(resolved)` here, // `ValueTyDefId` is just a convenient way to pass generics and // special-case enum variants resolved: ValueTyDefId, infer_args: bool, ) -> Substitution { let last = path.segments().last(); let (segment, generic_def) = match resolved { ValueTyDefId::FunctionId(it) => (last, Some(it.into())), ValueTyDefId::StructId(it) => (last, Some(it.into())), ValueTyDefId::UnionId(it) => (last, Some(it.into())), ValueTyDefId::ConstId(it) => (last, Some(it.into())), ValueTyDefId::StaticId(_) => (last, None), ValueTyDefId::EnumVariantId(var) => { // the generic args for an enum variant may be either specified // on the segment referring to the enum, or on the segment // referring to the variant. So `Option::::None` and // `Option::None::` are both allowed (though the former is // preferred). See also `def_ids_for_path_segments` in rustc. let len = path.segments().len(); let penultimate = len.checked_sub(2).and_then(|idx| path.segments().get(idx)); let segment = match penultimate { Some(segment) if segment.args_and_bindings.is_some() => Some(segment), _ => last, }; (segment, Some(var.parent.into())) } }; if let Some(segment) = segment { self.substs_from_path_segment(segment, generic_def, infer_args, None) } else if let Some(generic_def) = generic_def { // lang item self.substs_from_args_and_bindings(None, Some(generic_def), infer_args, None) } else { Substitution::empty(Interner) } } fn substs_from_path_segment( &self, segment: PathSegment<'_>, def: Option, infer_args: bool, explicit_self_ty: Option, ) -> Substitution { self.substs_from_args_and_bindings( segment.args_and_bindings, def, infer_args, explicit_self_ty, ) } fn substs_from_args_and_bindings( &self, args_and_bindings: Option<&GenericArgs>, def: Option, infer_args: bool, explicit_self_ty: Option, ) -> Substitution { // Remember that the item's own generic args come before its parent's. let mut substs = Vec::new(); let def = if let Some(d) = def { d } else { return Substitution::empty(Interner); }; let def_generics = generics(self.db.upcast(), def); let (parent_params, self_params, type_params, const_params, impl_trait_params) = def_generics.provenance_split(); let item_len = self_params + type_params + const_params + impl_trait_params; let total_len = parent_params + item_len; let ty_error = TyKind::Error.intern(Interner).cast(Interner); let mut def_generic_iter = def_generics.iter_id(); let fill_self_params = || { for x in explicit_self_ty .into_iter() .map(|x| x.cast(Interner)) .chain(iter::repeat(ty_error.clone())) .take(self_params) { if let Some(id) = def_generic_iter.next() { assert!(id.is_left()); substs.push(x); } } }; let mut had_explicit_args = false; if let Some(generic_args) = &args_and_bindings { if !generic_args.has_self_type { fill_self_params(); } let expected_num = if generic_args.has_self_type { self_params + type_params + const_params } else { type_params + const_params }; let skip = if generic_args.has_self_type && self_params == 0 { 1 } else { 0 }; // if args are provided, it should be all of them, but we can't rely on that for arg in generic_args .args .iter() .filter(|arg| !matches!(arg, GenericArg::Lifetime(_))) .skip(skip) .take(expected_num) { if let Some(id) = def_generic_iter.next() { if let Some(x) = generic_arg_to_chalk( self.db, id, arg, &mut (), |_, type_ref| self.lower_ty(type_ref), |_, c, ty| { const_or_path_to_chalk( self.db, self.resolver, ty, c, self.type_param_mode, || self.generics(), self.in_binders, ) }, ) { had_explicit_args = true; substs.push(x); } else { // we just filtered them out never!("Unexpected lifetime argument"); } } } } else { fill_self_params(); } // These params include those of parent. let remaining_params: SmallVec<[_; 2]> = def_generic_iter .map(|eid| match eid { Either::Left(_) => ty_error.clone(), Either::Right(x) => unknown_const_as_generic(self.db.const_param_ty(x)), }) .collect(); assert_eq!(remaining_params.len() + substs.len(), total_len); // handle defaults. In expression or pattern path segments without // explicitly specified type arguments, missing type arguments are inferred // (i.e. defaults aren't used). // Generic parameters for associated types are not supposed to have defaults, so we just // ignore them. let is_assoc_ty = if let GenericDefId::TypeAliasId(id) = def { let container = id.lookup(self.db.upcast()).container; matches!(container, ItemContainerId::TraitId(_)) } else { false }; if !is_assoc_ty && (!infer_args || had_explicit_args) { let defaults = self.db.generic_defaults(def); assert_eq!(total_len, defaults.len()); let parent_from = item_len - substs.len(); for (idx, default_ty) in defaults[substs.len()..item_len].iter().enumerate() { // each default can depend on the previous parameters let substs_so_far = Substitution::from_iter( Interner, substs.iter().cloned().chain(remaining_params[idx..].iter().cloned()), ); substs.push(default_ty.clone().substitute(Interner, &substs_so_far)); } // Keep parent's params as unknown. let mut remaining_params = remaining_params; substs.extend(remaining_params.drain(parent_from..)); } else { substs.extend(remaining_params); } assert_eq!(substs.len(), total_len); Substitution::from_iter(Interner, substs) } fn lower_trait_ref_from_path( &self, path: &Path, explicit_self_ty: Option, ) -> Option { let resolved = match self.resolver.resolve_path_in_type_ns_fully(self.db.upcast(), path)? { // FIXME(trait_alias): We need to handle trait alias here. TypeNs::TraitId(tr) => tr, _ => return None, }; let segment = path.segments().last().expect("path should have at least one segment"); Some(self.lower_trait_ref_from_resolved_path(resolved, segment, explicit_self_ty)) } pub(crate) fn lower_trait_ref_from_resolved_path( &self, resolved: TraitId, segment: PathSegment<'_>, explicit_self_ty: Option, ) -> TraitRef { let substs = self.trait_ref_substs_from_path(segment, resolved, explicit_self_ty); TraitRef { trait_id: to_chalk_trait_id(resolved), substitution: substs } } fn lower_trait_ref( &self, trait_ref: &HirTraitRef, explicit_self_ty: Option, ) -> Option { self.lower_trait_ref_from_path(&trait_ref.path, explicit_self_ty) } fn trait_ref_substs_from_path( &self, segment: PathSegment<'_>, resolved: TraitId, explicit_self_ty: Option, ) -> Substitution { self.substs_from_path_segment(segment, Some(resolved.into()), false, explicit_self_ty) } pub(crate) fn lower_where_predicate( &'a self, where_predicate: &'a WherePredicate, ignore_bindings: bool, ) -> impl Iterator + 'a { match where_predicate { WherePredicate::ForLifetime { target, bound, .. } | WherePredicate::TypeBound { target, bound } => { let self_ty = match target { WherePredicateTypeTarget::TypeRef(type_ref) => self.lower_ty(type_ref), WherePredicateTypeTarget::TypeOrConstParam(param_id) => { let generic_def = self.resolver.generic_def().expect("generics in scope"); let generics = generics(self.db.upcast(), generic_def); let param_id = hir_def::TypeOrConstParamId { parent: generic_def, local_id: *param_id, }; let placeholder = to_placeholder_idx(self.db, param_id); match self.type_param_mode { ParamLoweringMode::Placeholder => TyKind::Placeholder(placeholder), ParamLoweringMode::Variable => { let idx = generics.param_idx(param_id).expect("matching generics"); TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, idx)) } } .intern(Interner) } }; self.lower_type_bound(bound, self_ty, ignore_bindings) .collect::>() .into_iter() } WherePredicate::Lifetime { .. } => vec![].into_iter(), } } pub(crate) fn lower_type_bound( &'a self, bound: &'a TypeBound, self_ty: Ty, ignore_bindings: bool, ) -> impl Iterator + 'a { let mut bindings = None; let trait_ref = match bound { TypeBound::Path(path, TraitBoundModifier::None) => { bindings = self.lower_trait_ref_from_path(path, Some(self_ty)); bindings .clone() .filter(|tr| { // ignore `T: Drop` or `T: Destruct` bounds. // - `T: ~const Drop` has a special meaning in Rust 1.61 that we don't implement. // (So ideally, we'd only ignore `~const Drop` here) // - `Destruct` impls are built-in in 1.62 (current nightlies as of 08-04-2022), so until // the builtin impls are supported by Chalk, we ignore them here. if let Some(lang) = lang_attr(self.db.upcast(), tr.hir_trait_id()) { if matches!(lang, LangItem::Drop | LangItem::Destruct) { return false; } } true }) .map(WhereClause::Implemented) .map(crate::wrap_empty_binders) } TypeBound::Path(path, TraitBoundModifier::Maybe) => { let sized_trait = self .db .lang_item(self.resolver.krate(), LangItem::Sized) .and_then(|lang_item| lang_item.as_trait()); // Don't lower associated type bindings as the only possible relaxed trait bound // `?Sized` has no of them. // If we got another trait here ignore the bound completely. let trait_id = self .lower_trait_ref_from_path(path, Some(self_ty.clone())) .map(|trait_ref| trait_ref.hir_trait_id()); if trait_id == sized_trait { self.unsized_types.borrow_mut().insert(self_ty); } None } TypeBound::ForLifetime(_, path) => { // FIXME Don't silently drop the hrtb lifetimes here bindings = self.lower_trait_ref_from_path(path, Some(self_ty)); bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders) } TypeBound::Lifetime(_) => None, TypeBound::Error => None, }; trait_ref.into_iter().chain( bindings .into_iter() .filter(move |_| !ignore_bindings) .flat_map(move |tr| self.assoc_type_bindings_from_type_bound(bound, tr)), ) } fn assoc_type_bindings_from_type_bound( &'a self, bound: &'a TypeBound, trait_ref: TraitRef, ) -> impl Iterator + 'a { let last_segment = match bound { TypeBound::Path(path, TraitBoundModifier::None) | TypeBound::ForLifetime(_, path) => { path.segments().last() } TypeBound::Path(_, TraitBoundModifier::Maybe) | TypeBound::Error | TypeBound::Lifetime(_) => None, }; last_segment .into_iter() .filter_map(|segment| segment.args_and_bindings) .flat_map(|args_and_bindings| args_and_bindings.bindings.iter()) .flat_map(move |binding| { let found = associated_type_by_name_including_super_traits( self.db, trait_ref.clone(), &binding.name, ); let (super_trait_ref, associated_ty) = match found { None => return SmallVec::new(), Some(t) => t, }; // FIXME: `substs_from_path_segment()` pushes `TyKind::Error` for every parent // generic params. It's inefficient to splice the `Substitution`s, so we may want // that method to optionally take parent `Substitution` as we already know them at // this point (`super_trait_ref.substitution`). let substitution = self.substs_from_path_segment( // FIXME: This is hack. We shouldn't really build `PathSegment` directly. PathSegment { name: &binding.name, args_and_bindings: binding.args.as_deref() }, Some(associated_ty.into()), false, // this is not relevant Some(super_trait_ref.self_type_parameter(Interner)), ); let self_params = generics(self.db.upcast(), associated_ty.into()).len_self(); let substitution = Substitution::from_iter( Interner, substitution .iter(Interner) .take(self_params) .chain(super_trait_ref.substitution.iter(Interner)), ); let projection_ty = ProjectionTy { associated_ty_id: to_assoc_type_id(associated_ty), substitution, }; let mut preds: SmallVec<[_; 1]> = SmallVec::with_capacity( binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(), ); if let Some(type_ref) = &binding.type_ref { let ty = self.lower_ty(type_ref); let alias_eq = AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty }; preds.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq))); } for bound in binding.bounds.iter() { preds.extend(self.lower_type_bound( bound, TyKind::Alias(AliasTy::Projection(projection_ty.clone())).intern(Interner), false, )); } preds }) } fn lower_dyn_trait(&self, bounds: &[Interned]) -> Ty { let self_ty = TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(Interner); // INVARIANT: The principal trait bound, if present, must come first. Others may be in any // order but should be in the same order for the same set but possibly different order of // bounds in the input. // INVARIANT: If this function returns `DynTy`, there should be at least one trait bound. // These invariants are utilized by `TyExt::dyn_trait()` and chalk. let bounds = self.with_shifted_in(DebruijnIndex::ONE, |ctx| { let mut bounds: Vec<_> = bounds .iter() .flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false)) .collect(); let mut multiple_regular_traits = false; let mut multiple_same_projection = false; bounds.sort_unstable_by(|lhs, rhs| { use std::cmp::Ordering; match (lhs.skip_binders(), rhs.skip_binders()) { (WhereClause::Implemented(lhs), WhereClause::Implemented(rhs)) => { let lhs_id = lhs.trait_id; let lhs_is_auto = ctx.db.trait_data(from_chalk_trait_id(lhs_id)).is_auto; let rhs_id = rhs.trait_id; let rhs_is_auto = ctx.db.trait_data(from_chalk_trait_id(rhs_id)).is_auto; if !lhs_is_auto && !rhs_is_auto { multiple_regular_traits = true; } // Note that the ordering here is important; this ensures the invariant // mentioned above. (lhs_is_auto, lhs_id).cmp(&(rhs_is_auto, rhs_id)) } (WhereClause::Implemented(_), _) => Ordering::Less, (_, WhereClause::Implemented(_)) => Ordering::Greater, (WhereClause::AliasEq(lhs), WhereClause::AliasEq(rhs)) => { match (&lhs.alias, &rhs.alias) { (AliasTy::Projection(lhs_proj), AliasTy::Projection(rhs_proj)) => { // We only compare the `associated_ty_id`s. We shouldn't have // multiple bounds for an associated type in the correct Rust code, // and if we do, we error out. if lhs_proj.associated_ty_id == rhs_proj.associated_ty_id { multiple_same_projection = true; } lhs_proj.associated_ty_id.cmp(&rhs_proj.associated_ty_id) } // We don't produce `AliasTy::Opaque`s yet. _ => unreachable!(), } } // We don't produce `WhereClause::{TypeOutlives, LifetimeOutlives}` yet. _ => unreachable!(), } }); if multiple_regular_traits || multiple_same_projection { return None; } if bounds.first().and_then(|b| b.trait_id()).is_none() { // When there's no trait bound, that's an error. This happens when the trait refs // are unresolved. return None; } // As multiple occurrences of the same auto traits *are* permitted, we dedulicate the // bounds. We shouldn't have repeated elements besides auto traits at this point. bounds.dedup(); Some(QuantifiedWhereClauses::from_iter(Interner, bounds)) }); if let Some(bounds) = bounds { let bounds = crate::make_single_type_binders(bounds); TyKind::Dyn(DynTy { bounds, lifetime: static_lifetime() }).intern(Interner) } else { // FIXME: report error // (additional non-auto traits, associated type rebound, or no resolved trait) TyKind::Error.intern(Interner) } } fn lower_impl_trait( &self, bounds: &[Interned], func: FunctionId, ) -> ReturnTypeImplTrait { cov_mark::hit!(lower_rpit); let self_ty = TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(Interner); let predicates = self.with_shifted_in(DebruijnIndex::ONE, |ctx| { let mut predicates: Vec<_> = bounds .iter() .flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false)) .collect(); if !ctx.unsized_types.borrow().contains(&self_ty) { let krate = func.lookup(ctx.db.upcast()).module(ctx.db.upcast()).krate(); let sized_trait = ctx .db .lang_item(krate, LangItem::Sized) .and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id)); let sized_clause = sized_trait.map(|trait_id| { let clause = WhereClause::Implemented(TraitRef { trait_id, substitution: Substitution::from1(Interner, self_ty.clone()), }); crate::wrap_empty_binders(clause) }); predicates.extend(sized_clause.into_iter()); predicates.shrink_to_fit(); } predicates }); ReturnTypeImplTrait { bounds: crate::make_single_type_binders(predicates) } } } fn count_impl_traits(type_ref: &TypeRef) -> usize { let mut count = 0; type_ref.walk(&mut |type_ref| { if matches!(type_ref, TypeRef::ImplTrait(_)) { count += 1; } }); count } /// Build the signature of a callable item (function, struct or enum variant). pub(crate) fn callable_item_sig(db: &dyn HirDatabase, def: CallableDefId) -> PolyFnSig { match def { CallableDefId::FunctionId(f) => fn_sig_for_fn(db, f), CallableDefId::StructId(s) => fn_sig_for_struct_constructor(db, s), CallableDefId::EnumVariantId(e) => fn_sig_for_enum_variant_constructor(db, e), } } pub fn associated_type_shorthand_candidates( db: &dyn HirDatabase, def: GenericDefId, res: TypeNs, mut cb: impl FnMut(&Name, TypeAliasId) -> Option, ) -> Option { named_associated_type_shorthand_candidates(db, def, res, None, |name, _, id| cb(name, id)) } fn named_associated_type_shorthand_candidates( db: &dyn HirDatabase, // If the type parameter is defined in an impl and we're in a method, there // might be additional where clauses to consider def: GenericDefId, res: TypeNs, assoc_name: Option, // Do NOT let `cb` touch `TraitRef` outside of `TyLoweringContext`. Its substitution contains // free `BoundVar`s that need to be shifted and only `TyLoweringContext` knows how to do that // properly (see `TyLoweringContext::select_associated_type()`). mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option, ) -> Option { let mut search = |t| { all_super_trait_refs(db, t, |t| { let data = db.trait_data(t.hir_trait_id()); for (name, assoc_id) in &data.items { if let AssocItemId::TypeAliasId(alias) = assoc_id { if let Some(result) = cb(name, &t, *alias) { return Some(result); } } } None }) }; match res { TypeNs::SelfType(impl_id) => { // we're _in_ the impl -- the binders get added back later. Correct, // but it would be nice to make this more explicit let trait_ref = db.impl_trait(impl_id)?.into_value_and_skipped_binders().0; let impl_id_as_generic_def: GenericDefId = impl_id.into(); if impl_id_as_generic_def != def { // `trait_ref` contains `BoundVar`s bound by impl's `Binders`, but here we need // `BoundVar`s from `def`'s point of view. // FIXME: A `HirDatabase` query may be handy if this process is needed in more // places. It'd be almost identical as `impl_trait_query` where `resolver` would be // of `def` instead of `impl_id`. let starting_idx = generics(db.upcast(), def).len_self(); let subst = TyBuilder::subst_for_def(db, impl_id, None) .fill_with_bound_vars(DebruijnIndex::INNERMOST, starting_idx) .build(); let trait_ref = subst.apply(trait_ref, Interner); search(trait_ref) } else { search(trait_ref) } } TypeNs::GenericParam(param_id) => { let predicates = db.generic_predicates_for_param(def, param_id.into(), assoc_name); let res = predicates.iter().find_map(|pred| match pred.skip_binders().skip_binders() { // FIXME: how to correctly handle higher-ranked bounds here? WhereClause::Implemented(tr) => search( tr.clone() .shifted_out_to(Interner, DebruijnIndex::ONE) .expect("FIXME unexpected higher-ranked trait bound"), ), _ => None, }); if let Some(_) = res { return res; } // Handle `Self::Type` referring to own associated type in trait definitions if let GenericDefId::TraitId(trait_id) = param_id.parent() { let trait_generics = generics(db.upcast(), trait_id.into()); if trait_generics.params.type_or_consts[param_id.local_id()].is_trait_self() { let def_generics = generics(db.upcast(), def); let starting_idx = match def { GenericDefId::TraitId(_) => 0, // `def` is an item within trait. We need to substitute `BoundVar`s but // remember that they are for parent (i.e. trait) generic params so they // come after our own params. _ => def_generics.len_self(), }; let trait_ref = TyBuilder::trait_ref(db, trait_id) .fill_with_bound_vars(DebruijnIndex::INNERMOST, starting_idx) .build(); return search(trait_ref); } } None } _ => None, } } /// Build the type of all specific fields of a struct or enum variant. pub(crate) fn field_types_query( db: &dyn HirDatabase, variant_id: VariantId, ) -> Arc>> { let var_data = variant_id.variant_data(db.upcast()); let (resolver, def): (_, GenericDefId) = match variant_id { VariantId::StructId(it) => (it.resolver(db.upcast()), it.into()), VariantId::UnionId(it) => (it.resolver(db.upcast()), it.into()), VariantId::EnumVariantId(it) => (it.parent.resolver(db.upcast()), it.parent.into()), }; let generics = generics(db.upcast(), def); let mut res = ArenaMap::default(); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); for (field_id, field_data) in var_data.fields().iter() { res.insert(field_id, make_binders(db, &generics, ctx.lower_ty(&field_data.type_ref))); } Arc::new(res) } /// This query exists only to be used when resolving short-hand associated types /// like `T::Item`. /// /// See the analogous query in rustc and its comment: /// /// This is a query mostly to handle cycles somewhat gracefully; e.g. the /// following bounds are disallowed: `T: Foo, U: Foo`, but /// these are fine: `T: Foo, U: Foo<()>`. pub(crate) fn generic_predicates_for_param_query( db: &dyn HirDatabase, def: GenericDefId, param_id: TypeOrConstParamId, assoc_name: Option, ) -> Arc<[Binders]> { let resolver = def.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); let generics = generics(db.upcast(), def); let mut predicates: Vec<_> = resolver .where_predicates_in_scope() // we have to filter out all other predicates *first*, before attempting to lower them .filter(|pred| match pred { WherePredicate::ForLifetime { target, bound, .. } | WherePredicate::TypeBound { target, bound, .. } => { match target { WherePredicateTypeTarget::TypeRef(type_ref) => { if ctx.lower_ty_only_param(type_ref) != Some(param_id) { return false; } } &WherePredicateTypeTarget::TypeOrConstParam(local_id) => { let target_id = TypeOrConstParamId { parent: def, local_id }; if target_id != param_id { return false; } } }; match &**bound { TypeBound::ForLifetime(_, path) | TypeBound::Path(path, _) => { // Only lower the bound if the trait could possibly define the associated // type we're looking for. let assoc_name = match &assoc_name { Some(it) => it, None => return true, }; let tr = match resolver.resolve_path_in_type_ns_fully(db.upcast(), path) { Some(TypeNs::TraitId(tr)) => tr, _ => return false, }; all_super_traits(db.upcast(), tr).iter().any(|tr| { db.trait_data(*tr).items.iter().any(|(name, item)| { matches!(item, AssocItemId::TypeAliasId(_)) && name == assoc_name }) }) } TypeBound::Lifetime(_) | TypeBound::Error => false, } } WherePredicate::Lifetime { .. } => false, }) .flat_map(|pred| { ctx.lower_where_predicate(pred, true).map(|p| make_binders(db, &generics, p)) }) .collect(); let subst = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST); let explicitly_unsized_tys = ctx.unsized_types.into_inner(); let implicitly_sized_predicates = implicitly_sized_clauses(db, param_id.parent, &explicitly_unsized_tys, &subst, &resolver) .map(|p| make_binders(db, &generics, crate::wrap_empty_binders(p))); predicates.extend(implicitly_sized_predicates); predicates.into() } pub(crate) fn generic_predicates_for_param_recover( _db: &dyn HirDatabase, _cycle: &[String], _def: &GenericDefId, _param_id: &TypeOrConstParamId, _assoc_name: &Option, ) -> Arc<[Binders]> { Arc::new([]) } pub(crate) fn trait_environment_for_body_query( db: &dyn HirDatabase, def: DefWithBodyId, ) -> Arc { let Some(def) = def.as_generic_def_id() else { let krate = def.module(db.upcast()).krate(); return Arc::new(TraitEnvironment::empty(krate)); }; db.trait_environment(def) } pub(crate) fn trait_environment_query( db: &dyn HirDatabase, def: GenericDefId, ) -> Arc { let resolver = def.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Placeholder); let mut traits_in_scope = Vec::new(); let mut clauses = Vec::new(); for pred in resolver.where_predicates_in_scope() { for pred in ctx.lower_where_predicate(pred, false) { if let WhereClause::Implemented(tr) = &pred.skip_binders() { traits_in_scope.push((tr.self_type_parameter(Interner).clone(), tr.hir_trait_id())); } let program_clause: chalk_ir::ProgramClause = pred.cast(Interner); clauses.push(program_clause.into_from_env_clause(Interner)); } } let container: Option = match def { // FIXME: is there a function for this? GenericDefId::FunctionId(f) => Some(f.lookup(db.upcast()).container), GenericDefId::AdtId(_) => None, GenericDefId::TraitId(_) => None, GenericDefId::TraitAliasId(_) => None, GenericDefId::TypeAliasId(t) => Some(t.lookup(db.upcast()).container), GenericDefId::ImplId(_) => None, GenericDefId::EnumVariantId(_) => None, GenericDefId::ConstId(c) => Some(c.lookup(db.upcast()).container), }; if let Some(ItemContainerId::TraitId(trait_id)) = container { // add `Self: Trait` to the environment in trait // function default implementations (and speculative code // inside consts or type aliases) cov_mark::hit!(trait_self_implements_self); let substs = TyBuilder::placeholder_subst(db, trait_id); let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs }; let pred = WhereClause::Implemented(trait_ref); let program_clause: chalk_ir::ProgramClause = pred.cast(Interner); clauses.push(program_clause.into_from_env_clause(Interner)); } let subst = generics(db.upcast(), def).placeholder_subst(db); let explicitly_unsized_tys = ctx.unsized_types.into_inner(); let implicitly_sized_clauses = implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver).map(|pred| { let program_clause: chalk_ir::ProgramClause = pred.cast(Interner); program_clause.into_from_env_clause(Interner) }); clauses.extend(implicitly_sized_clauses); let krate = def.module(db.upcast()).krate(); let env = chalk_ir::Environment::new(Interner).add_clauses(Interner, clauses); Arc::new(TraitEnvironment { krate, block: None, traits_from_clauses: traits_in_scope, env }) } /// Resolve the where clause(s) of an item with generics. pub(crate) fn generic_predicates_query( db: &dyn HirDatabase, def: GenericDefId, ) -> Arc<[Binders]> { let resolver = def.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); let generics = generics(db.upcast(), def); let mut predicates = resolver .where_predicates_in_scope() .flat_map(|pred| { ctx.lower_where_predicate(pred, false).map(|p| make_binders(db, &generics, p)) }) .collect::>(); let subst = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST); let explicitly_unsized_tys = ctx.unsized_types.into_inner(); let implicitly_sized_predicates = implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver) .map(|p| make_binders(db, &generics, crate::wrap_empty_binders(p))); predicates.extend(implicitly_sized_predicates); predicates.into() } /// Generate implicit `: Sized` predicates for all generics that has no `?Sized` bound. /// Exception is Self of a trait def. fn implicitly_sized_clauses<'a>( db: &dyn HirDatabase, def: GenericDefId, explicitly_unsized_tys: &'a FxHashSet, substitution: &'a Substitution, resolver: &Resolver, ) -> impl Iterator + 'a { let is_trait_def = matches!(def, GenericDefId::TraitId(..)); let generic_args = &substitution.as_slice(Interner)[is_trait_def as usize..]; let sized_trait = db .lang_item(resolver.krate(), LangItem::Sized) .and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id)); sized_trait.into_iter().flat_map(move |sized_trait| { let implicitly_sized_tys = generic_args .iter() .filter_map(|generic_arg| generic_arg.ty(Interner)) .filter(move |&self_ty| !explicitly_unsized_tys.contains(self_ty)); implicitly_sized_tys.map(move |self_ty| { WhereClause::Implemented(TraitRef { trait_id: sized_trait, substitution: Substitution::from1(Interner, self_ty.clone()), }) }) }) } /// Resolve the default type params from generics pub(crate) fn generic_defaults_query( db: &dyn HirDatabase, def: GenericDefId, ) -> Arc<[Binders>]> { let resolver = def.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); let generic_params = generics(db.upcast(), def); let parent_start_idx = generic_params.len_self(); let defaults = generic_params .iter() .enumerate() .map(|(idx, (id, p))| { let p = match p { TypeOrConstParamData::TypeParamData(p) => p, TypeOrConstParamData::ConstParamData(_) => { // FIXME: implement const generic defaults let val = unknown_const_as_generic( db.const_param_ty(ConstParamId::from_unchecked(id)), ); return make_binders(db, &generic_params, val); } }; let mut ty = p.default.as_ref().map_or(TyKind::Error.intern(Interner), |t| ctx.lower_ty(t)); // Each default can only refer to previous parameters. // Type variable default referring to parameter coming // after it is forbidden (FIXME: report diagnostic) ty = fallback_bound_vars(ty, idx, parent_start_idx); crate::make_binders(db, &generic_params, ty.cast(Interner)) }) .collect(); defaults } pub(crate) fn generic_defaults_recover( db: &dyn HirDatabase, _cycle: &[String], def: &GenericDefId, ) -> Arc<[Binders]> { let generic_params = generics(db.upcast(), *def); // FIXME: this code is not covered in tests. // we still need one default per parameter let defaults = generic_params .iter_id() .map(|id| { let val = match id { Either::Left(_) => { GenericArgData::Ty(TyKind::Error.intern(Interner)).intern(Interner) } Either::Right(id) => unknown_const_as_generic(db.const_param_ty(id)), }; crate::make_binders(db, &generic_params, val) }) .collect(); defaults } fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig { let data = db.function_data(def); let resolver = def.resolver(db.upcast()); let ctx_params = TyLoweringContext::new(db, &resolver) .with_impl_trait_mode(ImplTraitLoweringMode::Variable) .with_type_param_mode(ParamLoweringMode::Variable); let params = data.params.iter().map(|(_, tr)| ctx_params.lower_ty(tr)).collect::>(); let ctx_ret = TyLoweringContext::new(db, &resolver) .with_impl_trait_mode(ImplTraitLoweringMode::Opaque) .with_type_param_mode(ParamLoweringMode::Variable); let ret = ctx_ret.lower_ty(&data.ret_type); let generics = generics(db.upcast(), def.into()); let sig = CallableSig::from_params_and_return( params, ret, data.is_varargs(), if data.has_unsafe_kw() { Safety::Unsafe } else { Safety::Safe }, ); make_binders(db, &generics, sig) } /// Build the declared type of a function. This should not need to look at the /// function body. fn type_for_fn(db: &dyn HirDatabase, def: FunctionId) -> Binders { let generics = generics(db.upcast(), def.into()); let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST); make_binders( db, &generics, TyKind::FnDef(CallableDefId::FunctionId(def).to_chalk(db), substs).intern(Interner), ) } /// Build the declared type of a const. fn type_for_const(db: &dyn HirDatabase, def: ConstId) -> Binders { let data = db.const_data(def); let generics = generics(db.upcast(), def.into()); let resolver = def.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); make_binders(db, &generics, ctx.lower_ty(&data.type_ref)) } /// Build the declared type of a static. fn type_for_static(db: &dyn HirDatabase, def: StaticId) -> Binders { let data = db.static_data(def); let resolver = def.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver); Binders::empty(Interner, ctx.lower_ty(&data.type_ref)) } fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnSig { let struct_data = db.struct_data(def); let fields = struct_data.variant_data.fields(); let resolver = def.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::>(); let (ret, binders) = type_for_adt(db, def.into()).into_value_and_skipped_binders(); Binders::new(binders, CallableSig::from_params_and_return(params, ret, false, Safety::Safe)) } /// Build the type of a tuple struct constructor. fn type_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> Binders { let struct_data = db.struct_data(def); if let StructKind::Unit = struct_data.variant_data.kind() { return type_for_adt(db, def.into()); } let generics = generics(db.upcast(), def.into()); let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST); make_binders( db, &generics, TyKind::FnDef(CallableDefId::StructId(def).to_chalk(db), substs).intern(Interner), ) } fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> PolyFnSig { let enum_data = db.enum_data(def.parent); let var_data = &enum_data.variants[def.local_id]; let fields = var_data.variant_data.fields(); let resolver = def.parent.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); let params = fields.iter().map(|(_, field)| ctx.lower_ty(&field.type_ref)).collect::>(); let (ret, binders) = type_for_adt(db, def.parent.into()).into_value_and_skipped_binders(); Binders::new(binders, CallableSig::from_params_and_return(params, ret, false, Safety::Safe)) } /// Build the type of a tuple enum variant constructor. fn type_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> Binders { let enum_data = db.enum_data(def.parent); let var_data = &enum_data.variants[def.local_id].variant_data; if let StructKind::Unit = var_data.kind() { return type_for_adt(db, def.parent.into()); } let generics = generics(db.upcast(), def.parent.into()); let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST); make_binders( db, &generics, TyKind::FnDef(CallableDefId::EnumVariantId(def).to_chalk(db), substs).intern(Interner), ) } fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders { let generics = generics(db.upcast(), adt.into()); let subst = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST); let ty = TyKind::Adt(crate::AdtId(adt), subst).intern(Interner); make_binders(db, &generics, ty) } fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders { let generics = generics(db.upcast(), t.into()); let resolver = t.resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); if db.type_alias_data(t).is_extern { Binders::empty(Interner, TyKind::Foreign(crate::to_foreign_def_id(t)).intern(Interner)) } else { let type_ref = &db.type_alias_data(t).type_ref; let inner = ctx.lower_ty(type_ref.as_deref().unwrap_or(&TypeRef::Error)); make_binders(db, &generics, inner) } } #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] pub enum CallableDefId { FunctionId(FunctionId), StructId(StructId), EnumVariantId(EnumVariantId), } impl_from!(FunctionId, StructId, EnumVariantId for CallableDefId); impl From for ModuleDefId { fn from(def: CallableDefId) -> ModuleDefId { match def { CallableDefId::FunctionId(f) => ModuleDefId::FunctionId(f), CallableDefId::StructId(s) => ModuleDefId::AdtId(AdtId::StructId(s)), CallableDefId::EnumVariantId(e) => ModuleDefId::EnumVariantId(e), } } } impl CallableDefId { pub fn krate(self, db: &dyn HirDatabase) -> CrateId { let db = db.upcast(); match self { CallableDefId::FunctionId(f) => f.lookup(db).module(db), CallableDefId::StructId(s) => s.lookup(db).container, CallableDefId::EnumVariantId(e) => e.parent.lookup(db).container, } .krate() } } impl From for GenericDefId { fn from(def: CallableDefId) -> GenericDefId { match def { CallableDefId::FunctionId(f) => f.into(), CallableDefId::StructId(s) => s.into(), CallableDefId::EnumVariantId(e) => e.into(), } } } #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] pub enum TyDefId { BuiltinType(BuiltinType), AdtId(AdtId), TypeAliasId(TypeAliasId), } impl_from!(BuiltinType, AdtId(StructId, EnumId, UnionId), TypeAliasId for TyDefId); #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] pub enum ValueTyDefId { FunctionId(FunctionId), StructId(StructId), UnionId(UnionId), EnumVariantId(EnumVariantId), ConstId(ConstId), StaticId(StaticId), } impl_from!(FunctionId, StructId, UnionId, EnumVariantId, ConstId, StaticId for ValueTyDefId); impl ValueTyDefId { pub(crate) fn to_generic_def_id(self) -> Option { match self { Self::FunctionId(id) => Some(id.into()), Self::StructId(id) => Some(id.into()), Self::UnionId(id) => Some(id.into()), Self::EnumVariantId(var) => Some(var.into()), Self::ConstId(id) => Some(id.into()), Self::StaticId(_) => None, } } } /// Build the declared type of an item. This depends on the namespace; e.g. for /// `struct Foo(usize)`, we have two types: The type of the struct itself, and /// the constructor function `(usize) -> Foo` which lives in the values /// namespace. pub(crate) fn ty_query(db: &dyn HirDatabase, def: TyDefId) -> Binders { match def { TyDefId::BuiltinType(it) => Binders::empty(Interner, TyBuilder::builtin(it)), TyDefId::AdtId(it) => type_for_adt(db, it), TyDefId::TypeAliasId(it) => type_for_type_alias(db, it), } } pub(crate) fn ty_recover(db: &dyn HirDatabase, _cycle: &[String], def: &TyDefId) -> Binders { let generics = match *def { TyDefId::BuiltinType(_) => return Binders::empty(Interner, TyKind::Error.intern(Interner)), TyDefId::AdtId(it) => generics(db.upcast(), it.into()), TyDefId::TypeAliasId(it) => generics(db.upcast(), it.into()), }; make_binders(db, &generics, TyKind::Error.intern(Interner)) } pub(crate) fn value_ty_query(db: &dyn HirDatabase, def: ValueTyDefId) -> Binders { match def { ValueTyDefId::FunctionId(it) => type_for_fn(db, it), ValueTyDefId::StructId(it) => type_for_struct_constructor(db, it), ValueTyDefId::UnionId(it) => type_for_adt(db, it.into()), ValueTyDefId::EnumVariantId(it) => type_for_enum_variant_constructor(db, it), ValueTyDefId::ConstId(it) => type_for_const(db, it), ValueTyDefId::StaticId(it) => type_for_static(db, it), } } pub(crate) fn impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binders { let impl_loc = impl_id.lookup(db.upcast()); let impl_data = db.impl_data(impl_id); let resolver = impl_id.resolver(db.upcast()); let _cx = stdx::panic_context::enter(format!( "impl_self_ty_query({impl_id:?} -> {impl_loc:?} -> {impl_data:?})" )); let generics = generics(db.upcast(), impl_id.into()); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); make_binders(db, &generics, ctx.lower_ty(&impl_data.self_ty)) } // returns None if def is a type arg pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty { let parent_data = db.generic_params(def.parent()); let data = &parent_data.type_or_consts[def.local_id()]; let resolver = def.parent().resolver(db.upcast()); let ctx = TyLoweringContext::new(db, &resolver); match data { TypeOrConstParamData::TypeParamData(_) => { never!(); Ty::new(Interner, TyKind::Error) } TypeOrConstParamData::ConstParamData(d) => ctx.lower_ty(&d.ty), } } pub(crate) fn impl_self_ty_recover( db: &dyn HirDatabase, _cycle: &[String], impl_id: &ImplId, ) -> Binders { let generics = generics(db.upcast(), (*impl_id).into()); make_binders(db, &generics, TyKind::Error.intern(Interner)) } pub(crate) fn impl_trait_query(db: &dyn HirDatabase, impl_id: ImplId) -> Option> { let impl_loc = impl_id.lookup(db.upcast()); let impl_data = db.impl_data(impl_id); let resolver = impl_id.resolver(db.upcast()); let _cx = stdx::panic_context::enter(format!( "impl_trait_query({impl_id:?} -> {impl_loc:?} -> {impl_data:?})" )); let ctx = TyLoweringContext::new(db, &resolver).with_type_param_mode(ParamLoweringMode::Variable); let (self_ty, binders) = db.impl_self_ty(impl_id).into_value_and_skipped_binders(); let target_trait = impl_data.target_trait.as_ref()?; Some(Binders::new(binders, ctx.lower_trait_ref(target_trait, Some(self_ty))?)) } pub(crate) fn return_type_impl_traits( db: &dyn HirDatabase, def: hir_def::FunctionId, ) -> Option>> { // FIXME unify with fn_sig_for_fn instead of doing lowering twice, maybe let data = db.function_data(def); let resolver = def.resolver(db.upcast()); let ctx_ret = TyLoweringContext::new(db, &resolver) .with_impl_trait_mode(ImplTraitLoweringMode::Opaque) .with_type_param_mode(ParamLoweringMode::Variable); let _ret = ctx_ret.lower_ty(&data.ret_type); let generics = generics(db.upcast(), def.into()); let return_type_impl_traits = ReturnTypeImplTraits { impl_traits: match ctx_ret.impl_trait_mode { ImplTraitLoweringState::Opaque(x) => x.into_inner(), _ => unreachable!(), }, }; if return_type_impl_traits.impl_traits.is_empty() { None } else { Some(Arc::new(make_binders(db, &generics, return_type_impl_traits))) } } pub(crate) fn lower_to_chalk_mutability(m: hir_def::type_ref::Mutability) -> Mutability { match m { hir_def::type_ref::Mutability::Shared => Mutability::Not, hir_def::type_ref::Mutability::Mut => Mutability::Mut, } } /// Checks if the provided generic arg matches its expected kind, then lower them via /// provided closures. Use unknown if there was kind mismatch. /// /// Returns `Some` of the lowered generic arg. `None` if the provided arg is a lifetime. pub(crate) fn generic_arg_to_chalk<'a, T>( db: &dyn HirDatabase, kind_id: Either, arg: &'a GenericArg, this: &mut T, for_type: impl FnOnce(&mut T, &TypeRef) -> Ty + 'a, for_const: impl FnOnce(&mut T, &ConstRefOrPath, Ty) -> Const + 'a, ) -> Option { let kind = match kind_id { Either::Left(_) => ParamKind::Type, Either::Right(id) => { let ty = db.const_param_ty(id); ParamKind::Const(ty) } }; Some(match (arg, kind) { (GenericArg::Type(type_ref), ParamKind::Type) => { let ty = for_type(this, type_ref); GenericArgData::Ty(ty).intern(Interner) } (GenericArg::Const(c), ParamKind::Const(c_ty)) => { GenericArgData::Const(for_const(this, c, c_ty)).intern(Interner) } (GenericArg::Const(_), ParamKind::Type) => { GenericArgData::Ty(TyKind::Error.intern(Interner)).intern(Interner) } (GenericArg::Type(t), ParamKind::Const(c_ty)) => { // We want to recover simple idents, which parser detects them // as types. Maybe here is not the best place to do it, but // it works. if let TypeRef::Path(p) = t { let p = p.mod_path()?; if p.kind == PathKind::Plain { if let [n] = p.segments() { let c = ConstRefOrPath::Path(n.clone()); return Some( GenericArgData::Const(for_const(this, &c, c_ty)).intern(Interner), ); } } } unknown_const_as_generic(c_ty) } (GenericArg::Lifetime(_), _) => return None, }) } pub(crate) fn const_or_path_to_chalk( db: &dyn HirDatabase, resolver: &Resolver, expected_ty: Ty, value: &ConstRefOrPath, mode: ParamLoweringMode, args: impl FnOnce() -> Generics, debruijn: DebruijnIndex, ) -> Const { match value { ConstRefOrPath::Scalar(s) => intern_const_ref(db, s, expected_ty, resolver.krate()), ConstRefOrPath::Path(n) => { let path = ModPath::from_segments(PathKind::Plain, Some(n.clone())); path_to_const( db, resolver, &Path::from_known_path_with_no_generic(path), mode, args, debruijn, ) .unwrap_or_else(|| unknown_const(expected_ty)) } } } /// Replaces any 'free' `BoundVar`s in `s` by `TyKind::Error` from the perspective of generic /// parameter whose index is `param_index`. A `BoundVar` is free when it is or (syntactically) /// appears after the generic parameter of `param_index`. fn fallback_bound_vars + HasInterner>( s: T, param_index: usize, parent_start: usize, ) -> T { // Keep in mind that parent generic parameters, if any, come *after* those of the item in // question. In the diagrams below, `c*` and `p*` represent generic parameters of the item and // its parent respectively. let is_allowed = |index| { if param_index < parent_start { // The parameter of `param_index` is one from the item in question. Any parent generic // parameters or the item's generic parameters that come before `param_index` is // allowed. // [c1, .., cj, .., ck, p1, .., pl] where cj is `param_index` // ^^^^^^ ^^^^^^^^^^ these are allowed !(param_index..parent_start).contains(&index) } else { // The parameter of `param_index` is one from the parent generics. Only parent generic // parameters that come before `param_index` are allowed. // [c1, .., ck, p1, .., pj, .., pl] where pj is `param_index` // ^^^^^^ these are allowed (parent_start..param_index).contains(&index) } }; crate::fold_free_vars( s, |bound, binders| { if bound.index_if_innermost().map_or(true, is_allowed) { bound.shifted_in_from(binders).to_ty(Interner) } else { TyKind::Error.intern(Interner) } }, |ty, bound, binders| { if bound.index_if_innermost().map_or(true, is_allowed) { bound.shifted_in_from(binders).to_const(Interner, ty) } else { unknown_const(ty) } }, ) }