rust/crates/hir_ty/src/traits/chalk/mapping.rs
2021-02-28 19:13:37 +01:00

710 lines
27 KiB
Rust

//! This module contains the implementations of the `ToChalk` trait, which
//! handles conversion between our data types and their corresponding types in
//! Chalk (in both directions); plus some helper functions for more specialized
//! conversions.
use chalk_ir::{
cast::Cast, fold::shift::Shift, interner::HasInterner, LifetimeData, PlaceholderIndex,
UniverseIndex,
};
use chalk_solve::rust_ir;
use base_db::salsa::InternKey;
use hir_def::{type_ref::Mutability, AssocContainerId, GenericDefId, Lookup, TypeAliasId};
use crate::{
db::HirDatabase,
primitive::UintTy,
traits::{Canonical, Obligation},
CallableDefId, GenericPredicate, InEnvironment, OpaqueTy, OpaqueTyId, ProjectionPredicate,
ProjectionTy, Scalar, Substs, TraitEnvironment, TraitRef, Ty, TyKind,
};
use super::interner::*;
use super::*;
impl ToChalk for Ty {
type Chalk = chalk_ir::Ty<Interner>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::Ty<Interner> {
match self {
Ty::Ref(m, parameters) => ref_to_chalk(db, m, parameters),
Ty::Array(parameters) => array_to_chalk(db, parameters),
Ty::FnPtr { num_args: _, is_varargs, substs } => {
let substitution = chalk_ir::FnSubst(substs.to_chalk(db).shifted_in(&Interner));
chalk_ir::TyKind::Function(chalk_ir::FnPointer {
num_binders: 0,
sig: chalk_ir::FnSig {
abi: (),
safety: chalk_ir::Safety::Safe,
variadic: is_varargs,
},
substitution,
})
.intern(&Interner)
}
Ty::AssociatedType(type_alias, substs) => {
let assoc_type = TypeAliasAsAssocType(type_alias);
let assoc_type_id = assoc_type.to_chalk(db);
let substitution = substs.to_chalk(db);
chalk_ir::TyKind::AssociatedType(assoc_type_id, substitution).intern(&Interner)
}
Ty::OpaqueType(impl_trait_id, substs) => {
let id = impl_trait_id.to_chalk(db);
let substitution = substs.to_chalk(db);
chalk_ir::TyKind::OpaqueType(id, substitution).intern(&Interner)
}
Ty::ForeignType(type_alias, _) => {
let foreign_type = TypeAliasAsForeignType(type_alias);
let foreign_type_id = foreign_type.to_chalk(db);
chalk_ir::TyKind::Foreign(foreign_type_id).intern(&Interner)
}
Ty::Scalar(scalar) => chalk_ir::TyKind::Scalar(scalar).intern(&Interner),
Ty::Tuple { cardinality, substs } => {
let substitution = substs.to_chalk(db);
chalk_ir::TyKind::Tuple(cardinality.into(), substitution).intern(&Interner)
}
Ty::RawPtr(mutability, substs) => {
let ty = substs[0].clone().to_chalk(db);
chalk_ir::TyKind::Raw(mutability.to_chalk(db), ty).intern(&Interner)
}
Ty::Slice(substs) => {
chalk_ir::TyKind::Slice(substs[0].clone().to_chalk(db)).intern(&Interner)
}
Ty::Str => chalk_ir::TyKind::Str.intern(&Interner),
Ty::FnDef(callable_def, substs) => {
let id = callable_def.to_chalk(db);
let substitution = substs.to_chalk(db);
chalk_ir::TyKind::FnDef(id, substitution).intern(&Interner)
}
Ty::Never => chalk_ir::TyKind::Never.intern(&Interner),
Ty::Closure { def, expr, substs } => {
let closure_id = db.intern_closure((def, expr));
let substitution = substs.to_chalk(db);
chalk_ir::TyKind::Closure(closure_id.into(), substitution).intern(&Interner)
}
Ty::Adt(adt_id, substs) => {
let substitution = substs.to_chalk(db);
chalk_ir::TyKind::Adt(chalk_ir::AdtId(adt_id), substitution).intern(&Interner)
}
Ty::Projection(proj_ty) => {
let associated_ty_id = TypeAliasAsAssocType(proj_ty.associated_ty).to_chalk(db);
let substitution = proj_ty.parameters.to_chalk(db);
chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
associated_ty_id,
substitution,
})
.cast(&Interner)
.intern(&Interner)
}
Ty::Placeholder(id) => {
let interned_id = db.intern_type_param_id(id);
PlaceholderIndex {
ui: UniverseIndex::ROOT,
idx: interned_id.as_intern_id().as_usize(),
}
.to_ty::<Interner>(&Interner)
}
Ty::Bound(idx) => chalk_ir::TyKind::BoundVar(idx).intern(&Interner),
Ty::Infer(_infer_ty) => panic!("uncanonicalized infer ty"),
Ty::Dyn(predicates) => {
let where_clauses = chalk_ir::QuantifiedWhereClauses::from_iter(
&Interner,
predicates.iter().filter(|p| !p.is_error()).cloned().map(|p| p.to_chalk(db)),
);
let bounded_ty = chalk_ir::DynTy {
bounds: make_binders(where_clauses, 1),
lifetime: LifetimeData::Static.intern(&Interner),
};
chalk_ir::TyKind::Dyn(bounded_ty).intern(&Interner)
}
Ty::Opaque(opaque_ty) => {
let opaque_ty_id = opaque_ty.opaque_ty_id.to_chalk(db);
let substitution = opaque_ty.parameters.to_chalk(db);
chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Opaque(chalk_ir::OpaqueTy {
opaque_ty_id,
substitution,
}))
.intern(&Interner)
}
Ty::Unknown => chalk_ir::TyKind::Error.intern(&Interner),
}
}
fn from_chalk(db: &dyn HirDatabase, chalk: chalk_ir::Ty<Interner>) -> Self {
match chalk.data(&Interner).kind.clone() {
chalk_ir::TyKind::Error => Ty::Unknown,
chalk_ir::TyKind::Array(ty, _size) => Ty::Array(Substs::single(from_chalk(db, ty))),
chalk_ir::TyKind::Placeholder(idx) => {
assert_eq!(idx.ui, UniverseIndex::ROOT);
let interned_id = crate::db::GlobalTypeParamId::from_intern_id(
crate::salsa::InternId::from(idx.idx),
);
Ty::Placeholder(db.lookup_intern_type_param_id(interned_id))
}
chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Projection(proj)) => {
let associated_ty =
from_chalk::<TypeAliasAsAssocType, _>(db, proj.associated_ty_id).0;
let parameters = from_chalk(db, proj.substitution);
Ty::Projection(ProjectionTy { associated_ty, parameters })
}
chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Opaque(opaque_ty)) => {
let impl_trait_id = from_chalk(db, opaque_ty.opaque_ty_id);
let parameters = from_chalk(db, opaque_ty.substitution);
Ty::Opaque(OpaqueTy { opaque_ty_id: impl_trait_id, parameters })
}
chalk_ir::TyKind::Function(chalk_ir::FnPointer {
num_binders,
sig: chalk_ir::FnSig { variadic, .. },
substitution,
..
}) => {
assert_eq!(num_binders, 0);
let parameters: Substs = from_chalk(
db,
substitution.0.shifted_out(&Interner).expect("fn ptr should have no binders"),
);
Ty::FnPtr {
num_args: (parameters.len() - 1) as u16,
is_varargs: variadic,
substs: parameters,
}
}
chalk_ir::TyKind::BoundVar(idx) => Ty::Bound(idx),
chalk_ir::TyKind::InferenceVar(_iv, _kind) => Ty::Unknown,
chalk_ir::TyKind::Dyn(where_clauses) => {
assert_eq!(where_clauses.bounds.binders.len(&Interner), 1);
let predicates = where_clauses
.bounds
.skip_binders()
.iter(&Interner)
.map(|c| from_chalk(db, c.clone()))
.collect();
Ty::Dyn(predicates)
}
chalk_ir::TyKind::Adt(struct_id, subst) => Ty::Adt(struct_id.0, from_chalk(db, subst)),
chalk_ir::TyKind::AssociatedType(type_id, subst) => Ty::AssociatedType(
from_chalk::<TypeAliasAsAssocType, _>(db, type_id).0,
from_chalk(db, subst),
),
chalk_ir::TyKind::OpaqueType(opaque_type_id, subst) => {
Ty::OpaqueType(from_chalk(db, opaque_type_id), from_chalk(db, subst))
}
chalk_ir::TyKind::Scalar(scalar) => Ty::Scalar(scalar),
chalk_ir::TyKind::Tuple(cardinality, subst) => {
Ty::Tuple { cardinality: cardinality as u16, substs: from_chalk(db, subst) }
}
chalk_ir::TyKind::Raw(mutability, ty) => {
Ty::RawPtr(from_chalk(db, mutability), Substs::single(from_chalk(db, ty)))
}
chalk_ir::TyKind::Slice(ty) => Ty::Slice(Substs::single(from_chalk(db, ty))),
chalk_ir::TyKind::Ref(mutability, _lifetime, ty) => {
Ty::Ref(from_chalk(db, mutability), Substs::single(from_chalk(db, ty)))
}
chalk_ir::TyKind::Str => Ty::Str,
chalk_ir::TyKind::Never => Ty::Never,
chalk_ir::TyKind::FnDef(fn_def_id, subst) => {
Ty::FnDef(from_chalk(db, fn_def_id), from_chalk(db, subst))
}
chalk_ir::TyKind::Closure(id, subst) => {
let id: crate::db::ClosureId = id.into();
let (def, expr) = db.lookup_intern_closure(id);
Ty::Closure { def, expr, substs: from_chalk(db, subst) }
}
chalk_ir::TyKind::Foreign(foreign_def_id) => Ty::ForeignType(
from_chalk::<TypeAliasAsForeignType, _>(db, foreign_def_id).0,
Substs::empty(),
),
chalk_ir::TyKind::Generator(_, _) => unimplemented!(), // FIXME
chalk_ir::TyKind::GeneratorWitness(_, _) => unimplemented!(), // FIXME
}
}
}
/// We currently don't model lifetimes, but Chalk does. So, we have to insert a
/// fake lifetime here, because Chalks built-in logic may expect it to be there.
fn ref_to_chalk(
db: &dyn HirDatabase,
mutability: Mutability,
subst: Substs,
) -> chalk_ir::Ty<Interner> {
let arg = subst[0].clone().to_chalk(db);
let lifetime = LifetimeData::Static.intern(&Interner);
chalk_ir::TyKind::Ref(mutability.to_chalk(db), lifetime, arg).intern(&Interner)
}
/// We currently don't model constants, but Chalk does. So, we have to insert a
/// fake constant here, because Chalks built-in logic may expect it to be there.
fn array_to_chalk(db: &dyn HirDatabase, subst: Substs) -> chalk_ir::Ty<Interner> {
let arg = subst[0].clone().to_chalk(db);
let usize_ty = chalk_ir::TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(&Interner);
let const_ = chalk_ir::ConstData {
ty: usize_ty,
value: chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst { interned: () }),
}
.intern(&Interner);
chalk_ir::TyKind::Array(arg, const_).intern(&Interner)
}
impl ToChalk for Substs {
type Chalk = chalk_ir::Substitution<Interner>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::Substitution<Interner> {
chalk_ir::Substitution::from_iter(&Interner, self.iter().map(|ty| ty.clone().to_chalk(db)))
}
fn from_chalk(db: &dyn HirDatabase, parameters: chalk_ir::Substitution<Interner>) -> Substs {
let tys = parameters
.iter(&Interner)
.map(|p| match p.ty(&Interner) {
Some(ty) => from_chalk(db, ty.clone()),
None => unimplemented!(),
})
.collect();
Substs(tys)
}
}
impl ToChalk for TraitRef {
type Chalk = chalk_ir::TraitRef<Interner>;
fn to_chalk(self: TraitRef, db: &dyn HirDatabase) -> chalk_ir::TraitRef<Interner> {
let trait_id = self.trait_.to_chalk(db);
let substitution = self.substs.to_chalk(db);
chalk_ir::TraitRef { trait_id, substitution }
}
fn from_chalk(db: &dyn HirDatabase, trait_ref: chalk_ir::TraitRef<Interner>) -> Self {
let trait_ = from_chalk(db, trait_ref.trait_id);
let substs = from_chalk(db, trait_ref.substitution);
TraitRef { trait_, substs }
}
}
impl ToChalk for hir_def::TraitId {
type Chalk = TraitId;
fn to_chalk(self, _db: &dyn HirDatabase) -> TraitId {
chalk_ir::TraitId(self.as_intern_id())
}
fn from_chalk(_db: &dyn HirDatabase, trait_id: TraitId) -> hir_def::TraitId {
InternKey::from_intern_id(trait_id.0)
}
}
impl ToChalk for OpaqueTyId {
type Chalk = chalk_ir::OpaqueTyId<Interner>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::OpaqueTyId<Interner> {
db.intern_impl_trait_id(self).into()
}
fn from_chalk(
db: &dyn HirDatabase,
opaque_ty_id: chalk_ir::OpaqueTyId<Interner>,
) -> OpaqueTyId {
db.lookup_intern_impl_trait_id(opaque_ty_id.into())
}
}
impl ToChalk for Mutability {
type Chalk = chalk_ir::Mutability;
fn to_chalk(self, _db: &dyn HirDatabase) -> Self::Chalk {
match self {
Mutability::Shared => chalk_ir::Mutability::Not,
Mutability::Mut => chalk_ir::Mutability::Mut,
}
}
fn from_chalk(_db: &dyn HirDatabase, chalk: Self::Chalk) -> Self {
match chalk {
chalk_ir::Mutability::Mut => Mutability::Mut,
chalk_ir::Mutability::Not => Mutability::Shared,
}
}
}
impl ToChalk for hir_def::ImplId {
type Chalk = ImplId;
fn to_chalk(self, _db: &dyn HirDatabase) -> ImplId {
chalk_ir::ImplId(self.as_intern_id())
}
fn from_chalk(_db: &dyn HirDatabase, impl_id: ImplId) -> hir_def::ImplId {
InternKey::from_intern_id(impl_id.0)
}
}
impl ToChalk for hir_def::AdtId {
type Chalk = AdtId;
fn to_chalk(self, _db: &dyn HirDatabase) -> Self::Chalk {
chalk_ir::AdtId(self.into())
}
fn from_chalk(_db: &dyn HirDatabase, id: AdtId) -> Self {
id.0
}
}
impl ToChalk for CallableDefId {
type Chalk = FnDefId;
fn to_chalk(self, db: &dyn HirDatabase) -> FnDefId {
db.intern_callable_def(self).into()
}
fn from_chalk(db: &dyn HirDatabase, fn_def_id: FnDefId) -> CallableDefId {
db.lookup_intern_callable_def(fn_def_id.into())
}
}
pub(crate) struct TypeAliasAsAssocType(pub(crate) TypeAliasId);
impl ToChalk for TypeAliasAsAssocType {
type Chalk = AssocTypeId;
fn to_chalk(self, _db: &dyn HirDatabase) -> AssocTypeId {
chalk_ir::AssocTypeId(self.0.as_intern_id())
}
fn from_chalk(_db: &dyn HirDatabase, assoc_type_id: AssocTypeId) -> TypeAliasAsAssocType {
TypeAliasAsAssocType(InternKey::from_intern_id(assoc_type_id.0))
}
}
pub(crate) struct TypeAliasAsForeignType(pub(crate) TypeAliasId);
impl ToChalk for TypeAliasAsForeignType {
type Chalk = ForeignDefId;
fn to_chalk(self, _db: &dyn HirDatabase) -> ForeignDefId {
chalk_ir::ForeignDefId(self.0.as_intern_id())
}
fn from_chalk(_db: &dyn HirDatabase, foreign_def_id: ForeignDefId) -> TypeAliasAsForeignType {
TypeAliasAsForeignType(InternKey::from_intern_id(foreign_def_id.0))
}
}
pub(crate) struct TypeAliasAsValue(pub(crate) TypeAliasId);
impl ToChalk for TypeAliasAsValue {
type Chalk = AssociatedTyValueId;
fn to_chalk(self, _db: &dyn HirDatabase) -> AssociatedTyValueId {
rust_ir::AssociatedTyValueId(self.0.as_intern_id())
}
fn from_chalk(
_db: &dyn HirDatabase,
assoc_ty_value_id: AssociatedTyValueId,
) -> TypeAliasAsValue {
TypeAliasAsValue(TypeAliasId::from_intern_id(assoc_ty_value_id.0))
}
}
impl ToChalk for GenericPredicate {
type Chalk = chalk_ir::QuantifiedWhereClause<Interner>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::QuantifiedWhereClause<Interner> {
match self {
GenericPredicate::Implemented(trait_ref) => {
let chalk_trait_ref = trait_ref.to_chalk(db);
let chalk_trait_ref = chalk_trait_ref.shifted_in(&Interner);
make_binders(chalk_ir::WhereClause::Implemented(chalk_trait_ref), 0)
}
GenericPredicate::Projection(projection_pred) => {
let ty = projection_pred.ty.to_chalk(db).shifted_in(&Interner);
let projection = projection_pred.projection_ty.to_chalk(db).shifted_in(&Interner);
let alias = chalk_ir::AliasTy::Projection(projection);
make_binders(chalk_ir::WhereClause::AliasEq(chalk_ir::AliasEq { alias, ty }), 0)
}
GenericPredicate::Error => panic!("tried passing GenericPredicate::Error to Chalk"),
}
}
fn from_chalk(
db: &dyn HirDatabase,
where_clause: chalk_ir::QuantifiedWhereClause<Interner>,
) -> GenericPredicate {
// we don't produce any where clauses with binders and can't currently deal with them
match where_clause
.skip_binders()
.clone()
.shifted_out(&Interner)
.expect("unexpected bound vars in where clause")
{
chalk_ir::WhereClause::Implemented(tr) => {
GenericPredicate::Implemented(from_chalk(db, tr))
}
chalk_ir::WhereClause::AliasEq(projection_eq) => {
let projection_ty = from_chalk(
db,
match projection_eq.alias {
chalk_ir::AliasTy::Projection(p) => p,
_ => unimplemented!(),
},
);
let ty = from_chalk(db, projection_eq.ty);
GenericPredicate::Projection(ProjectionPredicate { projection_ty, ty })
}
chalk_ir::WhereClause::LifetimeOutlives(_) => {
// we shouldn't get these from Chalk
panic!("encountered LifetimeOutlives from Chalk")
}
chalk_ir::WhereClause::TypeOutlives(_) => {
// we shouldn't get these from Chalk
panic!("encountered TypeOutlives from Chalk")
}
}
}
}
impl ToChalk for ProjectionTy {
type Chalk = chalk_ir::ProjectionTy<Interner>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::ProjectionTy<Interner> {
chalk_ir::ProjectionTy {
associated_ty_id: TypeAliasAsAssocType(self.associated_ty).to_chalk(db),
substitution: self.parameters.to_chalk(db),
}
}
fn from_chalk(
db: &dyn HirDatabase,
projection_ty: chalk_ir::ProjectionTy<Interner>,
) -> ProjectionTy {
ProjectionTy {
associated_ty: from_chalk::<TypeAliasAsAssocType, _>(
db,
projection_ty.associated_ty_id,
)
.0,
parameters: from_chalk(db, projection_ty.substitution),
}
}
}
impl ToChalk for ProjectionPredicate {
type Chalk = chalk_ir::AliasEq<Interner>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::AliasEq<Interner> {
chalk_ir::AliasEq {
alias: chalk_ir::AliasTy::Projection(self.projection_ty.to_chalk(db)),
ty: self.ty.to_chalk(db),
}
}
fn from_chalk(_db: &dyn HirDatabase, _normalize: chalk_ir::AliasEq<Interner>) -> Self {
unimplemented!()
}
}
impl ToChalk for Obligation {
type Chalk = chalk_ir::DomainGoal<Interner>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::DomainGoal<Interner> {
match self {
Obligation::Trait(tr) => tr.to_chalk(db).cast(&Interner),
Obligation::Projection(pr) => pr.to_chalk(db).cast(&Interner),
}
}
fn from_chalk(_db: &dyn HirDatabase, _goal: chalk_ir::DomainGoal<Interner>) -> Self {
unimplemented!()
}
}
impl<T> ToChalk for Canonical<T>
where
T: ToChalk,
T::Chalk: HasInterner<Interner = Interner>,
{
type Chalk = chalk_ir::Canonical<T::Chalk>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::Canonical<T::Chalk> {
let kinds = self
.kinds
.iter()
.map(|k| match k {
TyKind::General => chalk_ir::TyVariableKind::General,
TyKind::Integer => chalk_ir::TyVariableKind::Integer,
TyKind::Float => chalk_ir::TyVariableKind::Float,
})
.map(|tk| {
chalk_ir::CanonicalVarKind::new(
chalk_ir::VariableKind::Ty(tk),
chalk_ir::UniverseIndex::ROOT,
)
});
let value = self.value.to_chalk(db);
chalk_ir::Canonical {
value,
binders: chalk_ir::CanonicalVarKinds::from_iter(&Interner, kinds),
}
}
fn from_chalk(db: &dyn HirDatabase, canonical: chalk_ir::Canonical<T::Chalk>) -> Canonical<T> {
let kinds = canonical
.binders
.iter(&Interner)
.map(|k| match k.kind {
chalk_ir::VariableKind::Ty(tk) => match tk {
chalk_ir::TyVariableKind::General => TyKind::General,
chalk_ir::TyVariableKind::Integer => TyKind::Integer,
chalk_ir::TyVariableKind::Float => TyKind::Float,
},
// HACK: Chalk can sometimes return new lifetime variables. We
// want to just skip them, but to not mess up the indices of
// other variables, we'll just create a new type variable in
// their place instead. This should not matter (we never see the
// actual *uses* of the lifetime variable).
chalk_ir::VariableKind::Lifetime => TyKind::General,
chalk_ir::VariableKind::Const(_) => panic!("unexpected const from Chalk"),
})
.collect();
Canonical { kinds, value: from_chalk(db, canonical.value) }
}
}
impl ToChalk for Arc<TraitEnvironment> {
type Chalk = chalk_ir::Environment<Interner>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::Environment<Interner> {
let mut clauses = Vec::new();
for pred in &self.predicates {
if pred.is_error() {
// for env, we just ignore errors
continue;
}
let program_clause: chalk_ir::ProgramClause<Interner> =
pred.clone().to_chalk(db).cast(&Interner);
clauses.push(program_clause.into_from_env_clause(&Interner));
}
chalk_ir::Environment::new(&Interner).add_clauses(&Interner, clauses)
}
fn from_chalk(
_db: &dyn HirDatabase,
_env: chalk_ir::Environment<Interner>,
) -> Arc<TraitEnvironment> {
unimplemented!()
}
}
impl<T: ToChalk> ToChalk for InEnvironment<T>
where
T::Chalk: chalk_ir::interner::HasInterner<Interner = Interner>,
{
type Chalk = chalk_ir::InEnvironment<T::Chalk>;
fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::InEnvironment<T::Chalk> {
chalk_ir::InEnvironment {
environment: self.environment.to_chalk(db),
goal: self.value.to_chalk(db),
}
}
fn from_chalk(
db: &dyn HirDatabase,
in_env: chalk_ir::InEnvironment<T::Chalk>,
) -> InEnvironment<T> {
InEnvironment {
environment: from_chalk(db, in_env.environment),
value: from_chalk(db, in_env.goal),
}
}
}
pub(super) fn make_binders<T>(value: T, num_vars: usize) -> chalk_ir::Binders<T>
where
T: HasInterner<Interner = Interner>,
{
chalk_ir::Binders::new(
chalk_ir::VariableKinds::from_iter(
&Interner,
std::iter::repeat(chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General))
.take(num_vars),
),
value,
)
}
pub(super) fn convert_where_clauses(
db: &dyn HirDatabase,
def: GenericDefId,
substs: &Substs,
) -> Vec<chalk_ir::QuantifiedWhereClause<Interner>> {
let generic_predicates = db.generic_predicates(def);
let mut result = Vec::with_capacity(generic_predicates.len());
for pred in generic_predicates.iter() {
if pred.value.is_error() {
// skip errored predicates completely
continue;
}
result.push(pred.clone().subst(substs).to_chalk(db));
}
result
}
pub(super) fn generic_predicate_to_inline_bound(
db: &dyn HirDatabase,
pred: &GenericPredicate,
self_ty: &Ty,
) -> Option<rust_ir::InlineBound<Interner>> {
// An InlineBound is like a GenericPredicate, except the self type is left out.
// We don't have a special type for this, but Chalk does.
match pred {
GenericPredicate::Implemented(trait_ref) => {
if &trait_ref.substs[0] != self_ty {
// we can only convert predicates back to type bounds if they
// have the expected self type
return None;
}
let args_no_self = trait_ref.substs[1..]
.iter()
.map(|ty| ty.clone().to_chalk(db).cast(&Interner))
.collect();
let trait_bound =
rust_ir::TraitBound { trait_id: trait_ref.trait_.to_chalk(db), args_no_self };
Some(rust_ir::InlineBound::TraitBound(trait_bound))
}
GenericPredicate::Projection(proj) => {
if &proj.projection_ty.parameters[0] != self_ty {
return None;
}
let trait_ = match proj.projection_ty.associated_ty.lookup(db.upcast()).container {
AssocContainerId::TraitId(t) => t,
_ => panic!("associated type not in trait"),
};
let args_no_self = proj.projection_ty.parameters[1..]
.iter()
.map(|ty| ty.clone().to_chalk(db).cast(&Interner))
.collect();
let alias_eq_bound = rust_ir::AliasEqBound {
value: proj.ty.clone().to_chalk(db),
trait_bound: rust_ir::TraitBound { trait_id: trait_.to_chalk(db), args_no_self },
associated_ty_id: TypeAliasAsAssocType(proj.projection_ty.associated_ty)
.to_chalk(db),
parameters: Vec::new(), // FIXME we don't support generic associated types yet
};
Some(rust_ir::InlineBound::AliasEqBound(alias_eq_bound))
}
GenericPredicate::Error => None,
}
}