Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/lower.rs')
| -rw-r--r-- | crates/hir-ty/src/lower.rs | 1770 |
1 files changed, 1770 insertions, 0 deletions
diff --git a/crates/hir-ty/src/lower.rs b/crates/hir-ty/src/lower.rs new file mode 100644 index 0000000000..a3787728ea --- /dev/null +++ b/crates/hir-ty/src/lower.rs @@ -0,0 +1,1770 @@ +//! Methods for lowering the HIR to types. There are two main cases here: +//! +//! - Lowering a type reference like `&usize` or `Option<foo::bar::Baz>` to a +//! type: The entry point for this is `Ty::from_hir`. +//! - Building the type for an item: This happens through the `type_for_def` query. +//! +//! This usually involves resolving names, collecting generic arguments etc. +use std::cell::{Cell, RefCell}; +use std::{iter, sync::Arc}; + +use base_db::CrateId; +use chalk_ir::fold::Fold; +use chalk_ir::interner::HasInterner; +use chalk_ir::{cast::Cast, fold::Shift, Mutability, Safety}; +use hir_def::generics::TypeOrConstParamData; +use hir_def::intern::Interned; +use hir_def::lang_item::lang_attr; +use hir_def::path::{ModPath, PathKind}; +use hir_def::type_ref::ConstScalarOrPath; +use hir_def::{ + adt::StructKind, + body::{Expander, LowerCtx}, + builtin_type::BuiltinType, + generics::{TypeParamProvenance, WherePredicate, WherePredicateTypeTarget}, + path::{GenericArg, Path, PathSegment, PathSegments}, + resolver::{HasResolver, Resolver, TypeNs}, + type_ref::{TraitBoundModifier, TraitRef as HirTraitRef, TypeBound, TypeRef}, + AdtId, AssocItemId, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId, HasModule, + ImplId, ItemContainerId, LocalFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, + UnionId, VariantId, +}; +use hir_def::{ConstParamId, TypeOrConstParamId, TypeParamId}; +use hir_expand::{name::Name, ExpandResult}; +use itertools::Either; +use la_arena::ArenaMap; +use rustc_hash::FxHashSet; +use smallvec::SmallVec; +use stdx::{impl_from, never}; +use syntax::{ast, SmolStr}; + +use crate::consteval::{ + intern_scalar_const, path_to_const, unknown_const, unknown_const_as_generic, +}; +use crate::utils::Generics; +use crate::{all_super_traits, make_binders, Const, GenericArgData, ParamKind}; +use crate::{ + db::HirDatabase, + mapping::ToChalk, + static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx, + utils::{all_super_trait_refs, associated_type_by_name_including_super_traits, generics}, + AliasEq, AliasTy, Binders, BoundVar, CallableSig, DebruijnIndex, DynTy, FnPointer, FnSig, + FnSubst, ImplTraitId, Interner, PolyFnSig, ProjectionTy, QuantifiedWhereClause, + QuantifiedWhereClauses, ReturnTypeImplTrait, ReturnTypeImplTraits, Substitution, + TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyKind, WhereClause, +}; + +#[derive(Debug)] +pub struct TyLoweringContext<'a> { + pub db: &'a dyn HirDatabase, + pub 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, + pub impl_trait_mode: ImplTraitLoweringMode, + impl_trait_counter: Cell<u16>, + /// 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_type_data: RefCell<Vec<ReturnTypeImplTrait>>, + expander: RefCell<Option<Expander>>, + /// Tracks types with explicit `?Sized` bounds. + pub(crate) unsized_types: RefCell<FxHashSet<Ty>>, +} + +impl<'a> TyLoweringContext<'a> { + pub fn new(db: &'a dyn HirDatabase, resolver: &'a Resolver) -> Self { + let impl_trait_counter = Cell::new(0); + let impl_trait_mode = ImplTraitLoweringMode::Disallowed; + let type_param_mode = ParamLoweringMode::Placeholder; + let in_binders = DebruijnIndex::INNERMOST; + let opaque_type_data = RefCell::new(Vec::new()); + Self { + db, + resolver, + in_binders, + impl_trait_mode, + impl_trait_counter, + type_param_mode, + opaque_type_data, + expander: RefCell::new(None), + unsized_types: RefCell::default(), + } + } + + pub fn with_debruijn<T>( + &self, + debruijn: DebruijnIndex, + f: impl FnOnce(&TyLoweringContext) -> T, + ) -> T { + let opaque_ty_data_vec = self.opaque_type_data.take(); + let expander = self.expander.take(); + let unsized_types = self.unsized_types.take(); + let new_ctx = Self { + in_binders: debruijn, + impl_trait_counter: Cell::new(self.impl_trait_counter.get()), + opaque_type_data: RefCell::new(opaque_ty_data_vec), + expander: RefCell::new(expander), + unsized_types: RefCell::new(unsized_types), + ..*self + }; + let result = f(&new_ctx); + self.impl_trait_counter.set(new_ctx.impl_trait_counter.get()); + self.opaque_type_data.replace(new_ctx.opaque_type_data.into_inner()); + self.expander.replace(new_ctx.expander.into_inner()); + self.unsized_types.replace(new_ctx.unsized_types.into_inner()); + result + } + + pub fn with_shifted_in<T>( + &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, ..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<TypeNs>) { + 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(params, is_varargs) => { + 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: Safety::Safe, variadic: *is_varargs }, + substitution: FnSubst(substs), + }) + .intern(Interner) + } + TypeRef::DynTrait(bounds) => { + let self_ty = + TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(Interner); + let bounds = self.with_shifted_in(DebruijnIndex::ONE, |ctx| { + QuantifiedWhereClauses::from_iter( + Interner, + bounds.iter().flat_map(|b| ctx.lower_type_bound(b, self_ty.clone(), false)), + ) + }); + let bounds = crate::make_single_type_binders(bounds); + TyKind::Dyn(DynTy { bounds, lifetime: static_lifetime() }).intern(Interner) + } + TypeRef::ImplTrait(bounds) => { + match self.impl_trait_mode { + ImplTraitLoweringMode::Opaque => { + let idx = self.impl_trait_counter.get(); + self.impl_trait_counter.set(idx + 1); + let func = match self.resolver.generic_def() { + Some(GenericDefId::FunctionId(f)) => f, + _ => panic!("opaque impl trait lowering in non-function"), + }; + + assert!(idx as usize == self.opaque_type_data.borrow().len()); + // this dance is to make sure the data is in the right + // place even if we encounter more opaque types while + // lowering the bounds + self.opaque_type_data.borrow_mut().push(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<impl + // OtherTrait<T>>`, the `impl OtherTrait<T>` 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) + }); + self.opaque_type_data.borrow_mut()[idx as usize] = 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) + } + ImplTraitLoweringMode::Param => { + let idx = self.impl_trait_counter.get(); + // FIXME we're probably doing something wrong here + self.impl_trait_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 + .type_iter() + .filter(|(_, data)| { + 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) + } + } + ImplTraitLoweringMode::Variable => { + let idx = self.impl_trait_counter.get(); + // FIXME we're probably doing something wrong here + self.impl_trait_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 + parent_params + self_params + list_params + const_params, + )) + .intern(Interner) + } + ImplTraitLoweringMode::Disallowed => { + // FIXME: report error + TyKind::Error.intern(Interner) + } + } + } + TypeRef::Macro(macro_call) => { + let (expander, recursion_start) = { + let mut expander = self.expander.borrow_mut(); + if expander.is_some() { + (Some(expander), false) + } else { + *expander = Some(Expander::new( + self.db.upcast(), + macro_call.file_id, + self.resolver.module(), + )); + (Some(expander), true) + } + }; + let ty = if let Some(mut expander) = expander { + let expander_mut = expander.as_mut().unwrap(); + let macro_call = macro_call.to_node(self.db.upcast()); + match expander_mut.enter_expand::<ast::Type>(self.db.upcast(), macro_call) { + Ok(ExpandResult { value: Some((mark, expanded)), .. }) => { + let ctx = + LowerCtx::new(self.db.upcast(), expander_mut.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) + } + _ => None, + } + } else { + None + }; + 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<TypeOrConstParamId> { + 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.mod_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<TypeNs>, + remaining_segments: PathSegments<'_>, + ) -> (Ty, Option<TypeNs>) { + 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<TypeNs>) { + 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 handle type parameters on the segment + TyKind::Alias(AliasTy::Projection(ProjectionTy { + associated_ty_id: to_assoc_type_id(associated_ty), + substitution: trait_ref.substitution, + })) + .intern(Interner) + } + None => { + // FIXME: report error (associated type not found) + TyKind::Error.intern(Interner) + } + } + } + 0 => { + let self_ty = Some( + TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)) + .intern(Interner), + ); + let trait_ref = self.with_shifted_in(DebruijnIndex::ONE, |ctx| { + ctx.lower_trait_ref_from_resolved_path( + trait_, + resolved_segment, + self_ty, + ) + }); + let dyn_ty = DynTy { + bounds: crate::make_single_type_binders( + QuantifiedWhereClauses::from_iter( + Interner, + Some(crate::wrap_empty_binders(WhereClause::Implemented( + trait_ref, + ))), + ), + ), + lifetime: static_lifetime(), + }; + TyKind::Dyn(dyn_ty).intern(Interner) + } + _ => { + // FIXME report error (ambiguous associated type) + TyKind::Error.intern(Interner) + } + }; + return (ty, 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 = generics.param_idx(param_id.into()).expect("matching generics"); + TyKind::BoundVar(BoundVar::new(self.in_binders, idx)) + } + } + .intern(Interner) + } + TypeNs::SelfType(impl_id) => { + let generics = generics(self.db.upcast(), impl_id.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.impl_self_ty(impl_id).substitute(Interner, &substs) + } + 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<TypeNs>) { + // 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.mod_path()) { + Some(it) => it, + None => return (TyKind::Error.intern(Interner), 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<TypeNs>, segment: PathSegment<'_>) -> Ty { + let (def, res) = match (self.resolver.generic_def(), res) { + (Some(def), Some(res)) => (def, res), + _ => 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 { + let substs = 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(), + self.resolver + .generic_def() + .expect("there should be generics if there's a generic param"), + ); + let s = generics.placeholder_subst(self.db); + s.apply(t.substitution.clone(), Interner) + } + ParamLoweringMode::Variable => t.substitution.clone(), + }; + // We need to shift in the bound vars, since + // associated_type_shorthand_candidates does not do that + let substs = substs.shifted_in_from(Interner, self.in_binders); + // FIXME handle type parameters on the segment + Some( + TyKind::Alias(AliasTy::Projection(ProjectionTy { + associated_ty_id: to_assoc_type_id(associated_ty), + substitution: substs, + })) + .intern(Interner), + ) + } else { + None + } + }, + ); + + 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().expect("path should have at least one segment"); + 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::<T>::None` and + // `Option::None::<T>` 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() => segment, + _ => last, + }; + (segment, Some(var.parent.into())) + } + }; + self.substs_from_path_segment(segment, generic_def, infer_args, None) + } + + fn substs_from_path_segment( + &self, + segment: PathSegment<'_>, + def_generic: Option<GenericDefId>, + infer_args: bool, + explicit_self_ty: Option<Ty>, + ) -> Substitution { + let mut substs = Vec::new(); + let def_generics = if let Some(def) = def_generic { + generics(self.db.upcast(), def) + } else { + return Substitution::empty(Interner); + }; + let (parent_params, self_params, type_params, const_params, impl_trait_params) = + def_generics.provenance_split(); + let total_len = + parent_params + self_params + type_params + const_params + impl_trait_params; + + let ty_error = GenericArgData::Ty(TyKind::Error.intern(Interner)).intern(Interner); + + let mut def_generic_iter = def_generics.iter_id(); + + for _ in 0..parent_params { + if let Some(eid) = def_generic_iter.next() { + match eid { + Either::Left(_) => substs.push(ty_error.clone()), + Either::Right(x) => { + substs.push(unknown_const_as_generic(self.db.const_param_ty(x))) + } + } + } + } + + let fill_self_params = || { + for x in explicit_self_ty + .into_iter() + .map(|x| GenericArgData::Ty(x).intern(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) = &segment.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(); + } + + // handle defaults. In expression or pattern path segments without + // explicitly specified type arguments, missing type arguments are inferred + // (i.e. defaults aren't used). + if !infer_args || had_explicit_args { + if let Some(def_generic) = def_generic { + let defaults = self.db.generic_defaults(def_generic); + assert_eq!(total_len, defaults.len()); + + for default_ty in defaults.iter().skip(substs.len()) { + // each default can depend on the previous parameters + let substs_so_far = Substitution::from_iter(Interner, substs.clone()); + if let Some(_id) = def_generic_iter.next() { + substs.push(default_ty.clone().substitute(Interner, &substs_so_far)); + } + } + } + } + + // add placeholders for args that were not provided + // FIXME: emit diagnostics in contexts where this is not allowed + for eid in def_generic_iter { + match eid { + Either::Left(_) => substs.push(ty_error.clone()), + Either::Right(x) => { + substs.push(unknown_const_as_generic(self.db.const_param_ty(x))) + } + } + } + // If this assert fails, it means you pushed into subst but didn't call .next() of def_generic_iter + assert_eq!(substs.len(), total_len); + + Substitution::from_iter(Interner, substs) + } + + fn lower_trait_ref_from_path( + &self, + path: &Path, + explicit_self_ty: Option<Ty>, + ) -> Option<TraitRef> { + let resolved = + match self.resolver.resolve_path_in_type_ns_fully(self.db.upcast(), path.mod_path())? { + 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<Ty>, + ) -> 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<Ty>, + ) -> Option<TraitRef> { + 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<Ty>, + ) -> 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<Item = QuantifiedWhereClause> + '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::<Vec<_>>() + .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<Item = QuantifiedWhereClause> + '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 lang == "drop" || lang == "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(), SmolStr::new_inline("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<Item = QuantifiedWhereClause> + '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) + .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, + }; + let projection_ty = ProjectionTy { + associated_ty_id: to_assoc_type_id(associated_ty), + substitution: super_trait_ref.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 { + preds.extend(self.lower_type_bound( + bound, + TyKind::Alias(AliasTy::Projection(projection_ty.clone())).intern(Interner), + false, + )); + } + preds + }) + } + + fn lower_impl_trait( + &self, + bounds: &[Interned<TypeBound>], + 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, SmolStr::new_inline("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 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<R>( + db: &dyn HirDatabase, + def: GenericDefId, + res: TypeNs, + cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>, +) -> Option<R> { + named_associated_type_shorthand_candidates(db, def, res, None, cb) +} + +fn named_associated_type_shorthand_candidates<R>( + 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<Name>, + mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>, +) -> Option<R> { + let mut search = |t| { + for t in all_super_trait_refs(db, 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) => search( + // we're _in_ the impl -- the binders get added back later. Correct, + // but it would be nice to make this more explicit + db.impl_trait(impl_id)?.into_value_and_skipped_binders().0, + ), + 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 generics = generics(db.upcast(), trait_id.into()); + if generics.params.type_or_consts[param_id.local_id()].is_trait_self() { + let trait_ref = TyBuilder::trait_ref(db, trait_id) + .fill_with_bound_vars(DebruijnIndex::INNERMOST, 0) + .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<ArenaMap<LocalFieldId, Binders<Ty>>> { + 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: +/// <https://github.com/rust-lang/rust/blob/9150f844e2624eb013ec78ca08c1d416e6644026/src/librustc_typeck/astconv.rs#L46> +/// This is a query mostly to handle cycles somewhat gracefully; e.g. the +/// following bounds are disallowed: `T: Foo<U::Item>, U: Foo<T::Item>`, but +/// these are fine: `T: Foo<U::Item>, U: Foo<()>`. +pub(crate) fn generic_predicates_for_param_query( + db: &dyn HirDatabase, + def: GenericDefId, + param_id: TypeOrConstParamId, + assoc_name: Option<Name>, +) -> Arc<[Binders<QuantifiedWhereClause>]> { + 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) => { + if *local_id != param_id.local_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.mod_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<Name>, +) -> Arc<[Binders<QuantifiedWhereClause>]> { + Arc::new([]) +} + +pub(crate) fn trait_environment_query( + db: &dyn HirDatabase, + def: GenericDefId, +) -> Arc<TraitEnvironment> { + 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<Interner> = pred.cast(Interner); + clauses.push(program_clause.into_from_env_clause(Interner)); + } + } + + let container: Option<ItemContainerId> = 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::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<T1, T2, ...>` 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<Interner> = 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<Interner> = 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, 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<QuantifiedWhereClause>]> { + 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::<Vec<_>>(); + + 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<Ty>, + substitution: &'a Substitution, + resolver: &Resolver, +) -> impl Iterator<Item = WhereClause> + '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(), SmolStr::new_inline("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<chalk_ir::GenericArg<Interner>>]> { + 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 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 crate::make_binders_with_count(db, idx, &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. This is forbidden (FIXME: report + // diagnostic) + ty = fallback_bound_vars(ty, idx); + let val = GenericArgData::Ty(ty).intern(Interner); + crate::make_binders_with_count(db, idx, &generic_params, val) + }) + .collect(); + + defaults +} + +pub(crate) fn generic_defaults_recover( + db: &dyn HirDatabase, + _cycle: &[String], + def: &GenericDefId, +) -> Arc<[Binders<crate::GenericArg>]> { + 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() + .enumerate() + .map(|(count, id)| { + let val = match id { + itertools::Either::Left(_) => { + GenericArgData::Ty(TyKind::Error.intern(Interner)).intern(Interner) + } + itertools::Either::Right(id) => unknown_const_as_generic(db.const_param_ty(id)), + }; + crate::make_binders_with_count(db, count, &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::<Vec<_>>(); + 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()); + 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<Ty> { + 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<Ty> { + 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<Ty> { + 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::<Vec<_>>(); + 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)) +} + +/// Build the type of a tuple struct constructor. +fn type_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> Binders<Ty> { + 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::<Vec<_>>(); + 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)) +} + +/// Build the type of a tuple enum variant constructor. +fn type_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> Binders<Ty> { + 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<Ty> { + 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<Ty> { + 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 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<CallableDefId> 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); + +/// 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<Ty> { + 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<Ty> { + 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<Ty> { + 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<Ty> { + 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<Ty> { + 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<Binders<TraitRef>> { + 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<Arc<Binders<ReturnTypeImplTraits>>> { + // 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: ctx_ret.opaque_type_data.into_inner() }; + 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<TypeParamId, ConstParamId>, + arg: &'a GenericArg, + this: &mut T, + for_type: impl FnOnce(&mut T, &TypeRef) -> Ty + 'a, + for_const: impl FnOnce(&mut T, &ConstScalarOrPath, Ty) -> Const + 'a, +) -> Option<crate::GenericArg> { + 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 = ConstScalarOrPath::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: &ConstScalarOrPath, + mode: ParamLoweringMode, + args: impl FnOnce() -> Generics, + debruijn: DebruijnIndex, +) -> Const { + match value { + ConstScalarOrPath::Scalar(s) => intern_scalar_const(s.clone(), expected_ty), + ConstScalarOrPath::Path(n) => { + let path = ModPath::from_segments(PathKind::Plain, Some(n.clone())); + path_to_const(db, resolver, &path, mode, args, debruijn) + .unwrap_or_else(|| unknown_const(expected_ty)) + } + } +} + +/// This replaces any 'free' Bound vars in `s` (i.e. those with indices past +/// num_vars_to_keep) by `TyKind::Unknown`. +fn fallback_bound_vars<T: Fold<Interner> + HasInterner<Interner = Interner>>( + s: T, + num_vars_to_keep: usize, +) -> T::Result { + crate::fold_free_vars( + s, + |bound, binders| { + if bound.index >= num_vars_to_keep && bound.debruijn == DebruijnIndex::INNERMOST { + TyKind::Error.intern(Interner) + } else { + bound.shifted_in_from(binders).to_ty(Interner) + } + }, + |ty, bound, binders| { + if bound.index >= num_vars_to_keep && bound.debruijn == DebruijnIndex::INNERMOST { + unknown_const(ty.clone()) + } else { + bound.shifted_in_from(binders).to_const(Interner, ty) + } + }, + ) +} |