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lowering.rs
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//! Contains the logic to lower rustc types into Chalk types
//!
//! In many cases there is a 1:1 relationship between a rustc type and a Chalk type.
//! For example, a `SubstsRef` maps almost directly to a `Substitution`. In some
//! other cases, such as `Param`s, there is no Chalk type, so we have to handle
//! accordingly.
//!
//! ## `Ty` lowering
//! Much of the `Ty` lowering is 1:1 with Chalk. (Or will be eventually). A
//! helpful table for what types lower to what can be found in the
//! [Chalk book](https://rust-lang.github.io/chalk/book/types/rust_types.html).
//! The most notable difference lies with `Param`s. To convert from rustc to
//! Chalk, we eagerly and deeply convert `Param`s to placeholders (in goals) or
//! bound variables (for clause generation through functions in `db`).
//!
//! ## `Region` lowering
//! Regions are handled in rustc and Chalk is quite differently. In rustc, there
//! is a difference between "early bound" and "late bound" regions, where only
//! the late bound regions have a `DebruijnIndex`. Moreover, in Chalk all
//! regions (Lifetimes) have an associated index. In rustc, only `BrAnon`s have
//! an index, whereas `BrNamed` don't. In order to lower regions to Chalk, we
//! convert all regions into `BrAnon` late-bound regions.
//!
//! ## `Const` lowering
//! Chalk doesn't handle consts currently, so consts are currently lowered to
//! an empty tuple.
//!
//! ## Bound variable collection
//! Another difference between rustc and Chalk lies in the handling of binders.
//! Chalk requires that we store the bound parameter kinds, whereas rustc does
//! not. To lower anything wrapped in a `Binder`, we first deeply find any bound
//! variables from the current `Binder`.
use rustc_ast::ast;
use rustc_middle::traits::{ChalkEnvironmentAndGoal, ChalkRustInterner as RustInterner};
use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
use rustc_middle::ty::{
self, Binder, Region, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
TypeSuperVisitable, TypeVisitable, TypeVisitor,
};
use rustc_span::def_id::DefId;
use chalk_ir::{FnSig, ForeignDefId};
use rustc_hir::Unsafety;
use std::collections::btree_map::{BTreeMap, Entry};
use std::ops::ControlFlow;
/// Essentially an `Into` with a `&RustInterner` parameter
pub(crate) trait LowerInto<'tcx, T> {
/// Lower a rustc construct (e.g., `ty::TraitPredicate`) to a chalk type, consuming `self`.
fn lower_into(self, interner: RustInterner<'tcx>) -> T;
}
impl<'tcx> LowerInto<'tcx, chalk_ir::Substitution<RustInterner<'tcx>>> for SubstsRef<'tcx> {
fn lower_into(
self,
interner: RustInterner<'tcx>,
) -> chalk_ir::Substitution<RustInterner<'tcx>> {
chalk_ir::Substitution::from_iter(interner, self.iter().map(|s| s.lower_into(interner)))
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::Substitution<RustInterner<'tcx>>>
for &'tcx ty::List<Ty<'tcx>>
{
fn lower_into(
self,
interner: RustInterner<'tcx>,
) -> chalk_ir::Substitution<RustInterner<'tcx>> {
chalk_ir::Substitution::from_iter(
interner,
self.iter().map(|ty| GenericArg::from(ty).lower_into(interner)),
)
}
}
impl<'tcx> LowerInto<'tcx, SubstsRef<'tcx>> for &chalk_ir::Substitution<RustInterner<'tcx>> {
fn lower_into(self, interner: RustInterner<'tcx>) -> SubstsRef<'tcx> {
interner
.tcx
.mk_substs_from_iter(self.iter(interner).map(|subst| subst.lower_into(interner)))
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>>>
for ChalkEnvironmentAndGoal<'tcx>
{
fn lower_into(
self,
interner: RustInterner<'tcx>,
) -> chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>> {
let clauses = self.environment.into_iter().map(|predicate| {
let (predicate, binders, _named_regions) =
collect_bound_vars(interner, interner.tcx, predicate.kind());
let consequence = match predicate {
ty::ClauseKind::TypeWellFormedFromEnv(ty) => {
chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(ty.lower_into(interner)))
}
ty::ClauseKind::Trait(predicate) => chalk_ir::DomainGoal::FromEnv(
chalk_ir::FromEnv::Trait(predicate.trait_ref.lower_into(interner)),
),
ty::ClauseKind::RegionOutlives(predicate) => chalk_ir::DomainGoal::Holds(
chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
a: predicate.0.lower_into(interner),
b: predicate.1.lower_into(interner),
}),
),
ty::ClauseKind::TypeOutlives(predicate) => chalk_ir::DomainGoal::Holds(
chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
ty: predicate.0.lower_into(interner),
lifetime: predicate.1.lower_into(interner),
}),
),
ty::ClauseKind::Projection(predicate) => chalk_ir::DomainGoal::Holds(
chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)),
),
ty::ClauseKind::WellFormed(arg) => match arg.unpack() {
ty::GenericArgKind::Type(ty) => chalk_ir::DomainGoal::WellFormed(
chalk_ir::WellFormed::Ty(ty.lower_into(interner)),
),
// FIXME(chalk): we need to change `WellFormed` in Chalk to take a `GenericArg`
_ => chalk_ir::DomainGoal::WellFormed(chalk_ir::WellFormed::Ty(
interner.tcx.types.unit.lower_into(interner),
)),
},
ty::ClauseKind::ConstArgHasType(..) | ty::ClauseKind::ConstEvaluatable(_) => {
bug!("unexpected predicate {}", predicate)
}
};
let value = chalk_ir::ProgramClauseImplication {
consequence,
conditions: chalk_ir::Goals::empty(interner),
priority: chalk_ir::ClausePriority::High,
constraints: chalk_ir::Constraints::empty(interner),
};
chalk_ir::ProgramClauseData(chalk_ir::Binders::new(binders, value)).intern(interner)
});
let goal: chalk_ir::GoalData<RustInterner<'tcx>> = self.goal.lower_into(interner);
chalk_ir::InEnvironment {
environment: chalk_ir::Environment {
clauses: chalk_ir::ProgramClauses::from_iter(interner, clauses),
},
goal: goal.intern(interner),
}
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> for ty::Predicate<'tcx> {
fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
let (predicate, binders, _named_regions) =
collect_bound_vars(interner, interner.tcx, self.kind());
let value = match predicate {
ty::PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) => {
chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)),
))
}
ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(predicate)) => {
chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
a: predicate.0.lower_into(interner),
b: predicate.1.lower_into(interner),
}),
))
}
ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(predicate)) => {
chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
ty: predicate.0.lower_into(interner),
lifetime: predicate.1.lower_into(interner),
}),
))
}
ty::PredicateKind::Clause(ty::ClauseKind::Projection(predicate)) => {
chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)),
))
}
ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(arg)) => match arg.unpack() {
GenericArgKind::Type(ty) => match ty.kind() {
// FIXME(chalk): In Chalk, a placeholder is WellFormed if it
// `FromEnv`. However, when we "lower" Params, we don't update
// the environment.
ty::Placeholder(..) => {
chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner))
}
_ => chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::WellFormed(
chalk_ir::WellFormed::Ty(ty.lower_into(interner)),
)),
},
// FIXME(chalk): handle well formed consts
GenericArgKind::Const(..) => {
chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner))
}
GenericArgKind::Lifetime(lt) => bug!("unexpected well formed predicate: {:?}", lt),
},
ty::PredicateKind::ObjectSafe(t) => chalk_ir::GoalData::DomainGoal(
chalk_ir::DomainGoal::ObjectSafe(chalk_ir::TraitId(t)),
),
ty::PredicateKind::Subtype(ty::SubtypePredicate { a, b, a_is_expected: _ }) => {
chalk_ir::GoalData::SubtypeGoal(chalk_ir::SubtypeGoal {
a: a.lower_into(interner),
b: b.lower_into(interner),
})
}
// FIXME(chalk): other predicates
//
// We can defer this, but ultimately we'll want to express
// some of these in terms of chalk operations.
ty::PredicateKind::ClosureKind(..)
| ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(..))
| ty::PredicateKind::AliasRelate(..)
| ty::PredicateKind::Coerce(..)
| ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..))
| ty::PredicateKind::Ambiguous
| ty::PredicateKind::ConstEquate(..) => {
chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner))
}
ty::PredicateKind::Clause(ty::ClauseKind::TypeWellFormedFromEnv(ty)) => {
chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::FromEnv(
chalk_ir::FromEnv::Ty(ty.lower_into(interner)),
))
}
};
chalk_ir::GoalData::Quantified(
chalk_ir::QuantifierKind::ForAll,
chalk_ir::Binders::new(binders, value.intern(interner)),
)
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::TraitRef<RustInterner<'tcx>>>
for rustc_middle::ty::TraitRef<'tcx>
{
fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::TraitRef<RustInterner<'tcx>> {
chalk_ir::TraitRef {
trait_id: chalk_ir::TraitId(self.def_id),
substitution: self.substs.lower_into(interner),
}
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::AliasEq<RustInterner<'tcx>>>
for rustc_middle::ty::ProjectionPredicate<'tcx>
{
fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::AliasEq<RustInterner<'tcx>> {
// FIXME(associated_const_equality): teach chalk about terms for alias eq.
chalk_ir::AliasEq {
ty: self.term.ty().unwrap().lower_into(interner),
alias: chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
associated_ty_id: chalk_ir::AssocTypeId(self.projection_ty.def_id),
substitution: self.projection_ty.substs.lower_into(interner),
}),
}
}
}
/*
// FIXME(...): Where do I add this to Chalk? I can't find it in the rustc repo anywhere.
impl<'tcx> LowerInto<'tcx, chalk_ir::Term<RustInterner<'tcx>>> for rustc_middle::ty::Term<'tcx> {
fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Term<RustInterner<'tcx>> {
match self {
ty::Term::Ty(ty) => ty.lower_into(interner).into(),
ty::Term::Const(c) => c.lower_into(interner).into(),
}
}
}
*/
impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> {
fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Ty<RustInterner<'tcx>> {
let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i));
let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i));
let float = |f| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Float(f));
match *self.kind() {
ty::Bool => chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Bool),
ty::Char => chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Char),
ty::Int(ty) => match ty {
ty::IntTy::Isize => int(chalk_ir::IntTy::Isize),
ty::IntTy::I8 => int(chalk_ir::IntTy::I8),
ty::IntTy::I16 => int(chalk_ir::IntTy::I16),
ty::IntTy::I32 => int(chalk_ir::IntTy::I32),
ty::IntTy::I64 => int(chalk_ir::IntTy::I64),
ty::IntTy::I128 => int(chalk_ir::IntTy::I128),
},
ty::Uint(ty) => match ty {
ty::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
ty::UintTy::U8 => uint(chalk_ir::UintTy::U8),
ty::UintTy::U16 => uint(chalk_ir::UintTy::U16),
ty::UintTy::U32 => uint(chalk_ir::UintTy::U32),
ty::UintTy::U64 => uint(chalk_ir::UintTy::U64),
ty::UintTy::U128 => uint(chalk_ir::UintTy::U128),
},
ty::Float(ty) => match ty {
ty::FloatTy::F32 => float(chalk_ir::FloatTy::F32),
ty::FloatTy::F64 => float(chalk_ir::FloatTy::F64),
},
ty::Adt(def, substs) => {
chalk_ir::TyKind::Adt(chalk_ir::AdtId(def), substs.lower_into(interner))
}
ty::Foreign(def_id) => chalk_ir::TyKind::Foreign(ForeignDefId(def_id)),
ty::Str => chalk_ir::TyKind::Str,
ty::Array(ty, len) => {
chalk_ir::TyKind::Array(ty.lower_into(interner), len.lower_into(interner))
}
ty::Slice(ty) => chalk_ir::TyKind::Slice(ty.lower_into(interner)),
ty::RawPtr(ptr) => {
chalk_ir::TyKind::Raw(ptr.mutbl.lower_into(interner), ptr.ty.lower_into(interner))
}
ty::Ref(region, ty, mutability) => chalk_ir::TyKind::Ref(
mutability.lower_into(interner),
region.lower_into(interner),
ty.lower_into(interner),
),
ty::FnDef(def_id, substs) => {
chalk_ir::TyKind::FnDef(chalk_ir::FnDefId(def_id), substs.lower_into(interner))
}
ty::FnPtr(sig) => {
let (inputs_and_outputs, binders, _named_regions) =
collect_bound_vars(interner, interner.tcx, sig.inputs_and_output());
chalk_ir::TyKind::Function(chalk_ir::FnPointer {
num_binders: binders.len(interner),
sig: sig.lower_into(interner),
substitution: chalk_ir::FnSubst(chalk_ir::Substitution::from_iter(
interner,
inputs_and_outputs.iter().map(|ty| {
chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner)
}),
)),
})
}
// FIXME(dyn-star): handle the dynamic kind (dyn or dyn*)
ty::Dynamic(predicates, region, _kind) => chalk_ir::TyKind::Dyn(chalk_ir::DynTy {
bounds: predicates.lower_into(interner),
lifetime: region.lower_into(interner),
}),
ty::Closure(def_id, substs) => {
chalk_ir::TyKind::Closure(chalk_ir::ClosureId(def_id), substs.lower_into(interner))
}
ty::Generator(def_id, substs, _) => chalk_ir::TyKind::Generator(
chalk_ir::GeneratorId(def_id),
substs.lower_into(interner),
),
ty::GeneratorWitness(_) => unimplemented!(),
ty::GeneratorWitnessMIR(..) => unimplemented!(),
ty::Never => chalk_ir::TyKind::Never,
ty::Tuple(types) => chalk_ir::TyKind::Tuple(types.len(), types.lower_into(interner)),
ty::Alias(ty::Projection, ty::AliasTy { def_id, substs, .. }) => {
chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
associated_ty_id: chalk_ir::AssocTypeId(def_id),
substitution: substs.lower_into(interner),
}))
}
ty::Alias(ty::Weak, ty::AliasTy { .. }) => unimplemented!(),
ty::Alias(ty::Inherent, _) => unimplemented!(),
ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => {
chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Opaque(chalk_ir::OpaqueTy {
opaque_ty_id: chalk_ir::OpaqueTyId(def_id),
substitution: substs.lower_into(interner),
}))
}
// This should have been done eagerly prior to this, and all Params
// should have been substituted to placeholders
ty::Param(_) => panic!("Lowering Param when not expected."),
ty::Bound(db, bound) => chalk_ir::TyKind::BoundVar(chalk_ir::BoundVar::new(
chalk_ir::DebruijnIndex::new(db.as_u32()),
bound.var.index(),
)),
ty::Placeholder(_placeholder) => {
chalk_ir::TyKind::Placeholder(chalk_ir::PlaceholderIndex {
ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() },
idx: _placeholder.bound.var.as_usize(),
})
}
ty::Infer(_infer) => unimplemented!(),
ty::Error(_) => chalk_ir::TyKind::Error,
}
.intern(interner)
}
}
impl<'tcx> LowerInto<'tcx, Ty<'tcx>> for &chalk_ir::Ty<RustInterner<'tcx>> {
fn lower_into(self, interner: RustInterner<'tcx>) -> Ty<'tcx> {
use chalk_ir::TyKind;
let kind = match self.kind(interner) {
TyKind::Adt(struct_id, substitution) => {
ty::Adt(struct_id.0, substitution.lower_into(interner))
}
TyKind::Scalar(scalar) => match scalar {
chalk_ir::Scalar::Bool => ty::Bool,
chalk_ir::Scalar::Char => ty::Char,
chalk_ir::Scalar::Int(int_ty) => match int_ty {
chalk_ir::IntTy::Isize => ty::Int(ty::IntTy::Isize),
chalk_ir::IntTy::I8 => ty::Int(ty::IntTy::I8),
chalk_ir::IntTy::I16 => ty::Int(ty::IntTy::I16),
chalk_ir::IntTy::I32 => ty::Int(ty::IntTy::I32),
chalk_ir::IntTy::I64 => ty::Int(ty::IntTy::I64),
chalk_ir::IntTy::I128 => ty::Int(ty::IntTy::I128),
},
chalk_ir::Scalar::Uint(int_ty) => match int_ty {
chalk_ir::UintTy::Usize => ty::Uint(ty::UintTy::Usize),
chalk_ir::UintTy::U8 => ty::Uint(ty::UintTy::U8),
chalk_ir::UintTy::U16 => ty::Uint(ty::UintTy::U16),
chalk_ir::UintTy::U32 => ty::Uint(ty::UintTy::U32),
chalk_ir::UintTy::U64 => ty::Uint(ty::UintTy::U64),
chalk_ir::UintTy::U128 => ty::Uint(ty::UintTy::U128),
},
chalk_ir::Scalar::Float(float_ty) => match float_ty {
chalk_ir::FloatTy::F32 => ty::Float(ty::FloatTy::F32),
chalk_ir::FloatTy::F64 => ty::Float(ty::FloatTy::F64),
},
},
TyKind::Array(ty, c) => {
let ty = ty.lower_into(interner);
let c = c.lower_into(interner);
ty::Array(ty, c)
}
TyKind::FnDef(id, substitution) => ty::FnDef(id.0, substitution.lower_into(interner)),
TyKind::Closure(closure, substitution) => {
ty::Closure(closure.0, substitution.lower_into(interner))
}
TyKind::Generator(generator, substitution) => ty::Generator(
generator.0,
substitution.lower_into(interner),
ast::Movability::Static,
),
TyKind::GeneratorWitness(..) => unimplemented!(),
TyKind::Never => ty::Never,
TyKind::Tuple(_len, substitution) => {
ty::Tuple(substitution.lower_into(interner).into_type_list(interner.tcx))
}
TyKind::Slice(ty) => ty::Slice(ty.lower_into(interner)),
TyKind::Raw(mutbl, ty) => ty::RawPtr(ty::TypeAndMut {
ty: ty.lower_into(interner),
mutbl: mutbl.lower_into(interner),
}),
TyKind::Ref(mutbl, lifetime, ty) => ty::Ref(
lifetime.lower_into(interner),
ty.lower_into(interner),
mutbl.lower_into(interner),
),
TyKind::Str => ty::Str,
TyKind::OpaqueType(opaque_ty, substitution) => ty::Alias(
ty::Opaque,
interner.tcx.mk_alias_ty(opaque_ty.0, substitution.lower_into(interner)),
),
TyKind::AssociatedType(assoc_ty, substitution) => ty::Alias(
ty::Projection,
interner.tcx.mk_alias_ty(assoc_ty.0, substitution.lower_into(interner)),
),
TyKind::Foreign(def_id) => ty::Foreign(def_id.0),
TyKind::Error => return interner.tcx.ty_error_misc(),
TyKind::Alias(alias_ty) => match alias_ty {
chalk_ir::AliasTy::Projection(projection) => ty::Alias(
ty::Projection,
interner.tcx.mk_alias_ty(
projection.associated_ty_id.0,
projection.substitution.lower_into(interner),
),
),
chalk_ir::AliasTy::Opaque(opaque) => ty::Alias(
ty::Opaque,
interner.tcx.mk_alias_ty(
opaque.opaque_ty_id.0,
opaque.substitution.lower_into(interner),
),
),
},
TyKind::Function(_quantified_ty) => unimplemented!(),
TyKind::BoundVar(bound) => ty::Bound(
ty::DebruijnIndex::from_usize(bound.debruijn.depth() as usize),
ty::BoundTy {
var: ty::BoundVar::from_usize(bound.index),
kind: ty::BoundTyKind::Anon,
},
),
TyKind::Placeholder(placeholder) => ty::Placeholder(ty::Placeholder {
universe: ty::UniverseIndex::from_usize(placeholder.ui.counter),
bound: ty::BoundTy {
var: ty::BoundVar::from_usize(placeholder.idx),
kind: ty::BoundTyKind::Anon,
},
}),
TyKind::InferenceVar(_, _) => unimplemented!(),
TyKind::Dyn(_) => unimplemented!(),
};
interner.tcx.mk_ty_from_kind(kind)
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'tcx> {
fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Lifetime<RustInterner<'tcx>> {
match *self {
ty::ReEarlyBound(_) => {
panic!("Should have already been substituted.");
}
ty::ReError(_) => {
panic!("Error lifetime should not have already been lowered.");
}
ty::ReLateBound(db, br) => chalk_ir::LifetimeData::BoundVar(chalk_ir::BoundVar::new(
chalk_ir::DebruijnIndex::new(db.as_u32()),
br.var.as_usize(),
))
.intern(interner),
ty::ReFree(_) => unimplemented!(),
ty::ReStatic => chalk_ir::LifetimeData::Static.intern(interner),
ty::ReVar(_) => unimplemented!(),
ty::RePlaceholder(placeholder_region) => {
chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex {
ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() },
idx: 0, // FIXME: This `idx: 0` is sus.
})
.intern(interner)
}
ty::ReErased => chalk_ir::LifetimeData::Erased.intern(interner),
}
}
}
impl<'tcx> LowerInto<'tcx, Region<'tcx>> for &chalk_ir::Lifetime<RustInterner<'tcx>> {
fn lower_into(self, interner: RustInterner<'tcx>) -> Region<'tcx> {
let tcx = interner.tcx;
match self.data(interner) {
chalk_ir::LifetimeData::BoundVar(var) => ty::Region::new_late_bound(
tcx,
ty::DebruijnIndex::from_u32(var.debruijn.depth()),
ty::BoundRegion {
var: ty::BoundVar::from_usize(var.index),
kind: ty::BrAnon(None),
},
),
chalk_ir::LifetimeData::InferenceVar(_var) => unimplemented!(),
chalk_ir::LifetimeData::Placeholder(p) => ty::Region::new_placeholder(
tcx,
ty::Placeholder {
universe: ty::UniverseIndex::from_usize(p.ui.counter),
bound: ty::BoundRegion {
var: ty::BoundVar::from_usize(p.idx),
kind: ty::BoundRegionKind::BrAnon(None),
},
},
),
chalk_ir::LifetimeData::Static => tcx.lifetimes.re_static,
chalk_ir::LifetimeData::Erased => tcx.lifetimes.re_erased,
#[cfg(bootstrap)]
chalk_ir::LifetimeData::Phantom(void, _) => match *void {},
}
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::Const<RustInterner<'tcx>>> for ty::Const<'tcx> {
fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::Const<RustInterner<'tcx>> {
let ty = self.ty().lower_into(interner);
let value = match self.kind() {
ty::ConstKind::Value(val) => {
chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst { interned: val })
}
ty::ConstKind::Bound(db, bound) => chalk_ir::ConstValue::BoundVar(
chalk_ir::BoundVar::new(chalk_ir::DebruijnIndex::new(db.as_u32()), bound.index()),
),
_ => unimplemented!("Const not implemented. {:?}", self),
};
chalk_ir::ConstData { ty, value }.intern(interner)
}
}
impl<'tcx> LowerInto<'tcx, ty::Const<'tcx>> for &chalk_ir::Const<RustInterner<'tcx>> {
fn lower_into(self, interner: RustInterner<'tcx>) -> ty::Const<'tcx> {
let data = self.data(interner);
let ty = data.ty.lower_into(interner);
let kind = match data.value {
chalk_ir::ConstValue::BoundVar(var) => ty::ConstKind::Bound(
ty::DebruijnIndex::from_u32(var.debruijn.depth()),
ty::BoundVar::from_u32(var.index as u32),
),
chalk_ir::ConstValue::InferenceVar(_var) => unimplemented!(),
chalk_ir::ConstValue::Placeholder(_p) => unimplemented!(),
chalk_ir::ConstValue::Concrete(c) => ty::ConstKind::Value(c.interned),
};
interner.tcx.mk_const(kind, ty)
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::GenericArg<RustInterner<'tcx>>> for GenericArg<'tcx> {
fn lower_into(self, interner: RustInterner<'tcx>) -> chalk_ir::GenericArg<RustInterner<'tcx>> {
match self.unpack() {
ty::subst::GenericArgKind::Type(ty) => {
chalk_ir::GenericArgData::Ty(ty.lower_into(interner))
}
ty::subst::GenericArgKind::Lifetime(lifetime) => {
chalk_ir::GenericArgData::Lifetime(lifetime.lower_into(interner))
}
ty::subst::GenericArgKind::Const(c) => {
chalk_ir::GenericArgData::Const(c.lower_into(interner))
}
}
.intern(interner)
}
}
impl<'tcx> LowerInto<'tcx, ty::subst::GenericArg<'tcx>>
for &chalk_ir::GenericArg<RustInterner<'tcx>>
{
fn lower_into(self, interner: RustInterner<'tcx>) -> ty::subst::GenericArg<'tcx> {
match self.data(interner) {
chalk_ir::GenericArgData::Ty(ty) => {
let t: Ty<'tcx> = ty.lower_into(interner);
t.into()
}
chalk_ir::GenericArgData::Lifetime(lifetime) => {
let r: Region<'tcx> = lifetime.lower_into(interner);
r.into()
}
chalk_ir::GenericArgData::Const(c) => {
let c: ty::Const<'tcx> = c.lower_into(interner);
c.into()
}
}
}
}
// We lower into an Option here since there are some predicates which Chalk
// doesn't have a representation for yet (as a `WhereClause`), but are so common
// that we just are accepting the unsoundness for now. The `Option` will
// eventually be removed.
impl<'tcx> LowerInto<'tcx, Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>
for ty::Predicate<'tcx>
{
fn lower_into(
self,
interner: RustInterner<'tcx>,
) -> Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> {
let (predicate, binders, _named_regions) =
collect_bound_vars(interner, interner.tcx, self.kind());
let value = match predicate {
ty::PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) => {
Some(chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)))
}
ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(predicate)) => {
Some(chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
a: predicate.0.lower_into(interner),
b: predicate.1.lower_into(interner),
}))
}
ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(predicate)) => {
Some(chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
ty: predicate.0.lower_into(interner),
lifetime: predicate.1.lower_into(interner),
}))
}
ty::PredicateKind::Clause(ty::ClauseKind::Projection(predicate)) => {
Some(chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)))
}
ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_ty)) => None,
ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(..)) => None,
ty::PredicateKind::ObjectSafe(..)
| ty::PredicateKind::AliasRelate(..)
| ty::PredicateKind::ClosureKind(..)
| ty::PredicateKind::Subtype(..)
| ty::PredicateKind::Coerce(..)
| ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..))
| ty::PredicateKind::ConstEquate(..)
| ty::PredicateKind::Ambiguous
| ty::PredicateKind::Clause(ty::ClauseKind::TypeWellFormedFromEnv(..)) => {
bug!("unexpected predicate {self}")
}
};
value.map(|value| chalk_ir::Binders::new(binders, value))
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>>>
for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>
{
fn lower_into(
self,
interner: RustInterner<'tcx>,
) -> chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>> {
// `Self` has one binder:
// Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>
// The return type has two:
// Binders<&[Binders<WhereClause<I>>]>
// This means that any variables that are escaping `self` need to be
// shifted in by one so that they are still escaping.
let predicates = ty::fold::shift_vars(interner.tcx, self, 1);
let self_ty = interner.tcx.mk_bound(
// This is going to be wrapped in a binder
ty::DebruijnIndex::from_usize(1),
ty::BoundTy { var: ty::BoundVar::from_usize(0), kind: ty::BoundTyKind::Anon },
);
let where_clauses = predicates.into_iter().map(|predicate| {
let (predicate, binders, _named_regions) =
collect_bound_vars(interner, interner.tcx, predicate);
match predicate {
ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef { def_id, substs }) => {
chalk_ir::Binders::new(
binders.clone(),
chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
trait_id: chalk_ir::TraitId(def_id),
substitution: interner
.tcx
.mk_substs_trait(self_ty, substs)
.lower_into(interner),
}),
)
}
ty::ExistentialPredicate::Projection(predicate) => chalk_ir::Binders::new(
binders.clone(),
chalk_ir::WhereClause::AliasEq(chalk_ir::AliasEq {
alias: chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
associated_ty_id: chalk_ir::AssocTypeId(predicate.def_id),
substitution: interner
.tcx
.mk_substs_trait(self_ty, predicate.substs)
.lower_into(interner),
}),
// FIXME(associated_const_equality): teach chalk about terms for alias eq.
ty: predicate.term.ty().unwrap().lower_into(interner),
}),
),
ty::ExistentialPredicate::AutoTrait(def_id) => chalk_ir::Binders::new(
binders.clone(),
chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
trait_id: chalk_ir::TraitId(def_id),
substitution: interner
.tcx
.mk_substs_trait(self_ty, [])
.lower_into(interner),
}),
),
}
});
// Binder for the bound variable representing the concrete underlying type.
let existential_binder = chalk_ir::VariableKinds::from1(
interner,
chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
);
let value = chalk_ir::QuantifiedWhereClauses::from_iter(interner, where_clauses);
chalk_ir::Binders::new(existential_binder, value)
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::FnSig<RustInterner<'tcx>>>
for ty::Binder<'tcx, ty::FnSig<'tcx>>
{
fn lower_into(self, _interner: RustInterner<'_>) -> FnSig<RustInterner<'tcx>> {
chalk_ir::FnSig {
abi: self.abi(),
safety: match self.unsafety() {
Unsafety::Normal => chalk_ir::Safety::Safe,
Unsafety::Unsafe => chalk_ir::Safety::Unsafe,
},
variadic: self.c_variadic(),
}
}
}
// We lower into an Option here since there are some predicates which Chalk
// doesn't have a representation for yet (as an `InlineBound`). The `Option` will
// eventually be removed.
impl<'tcx> LowerInto<'tcx, Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>>>
for ty::Predicate<'tcx>
{
fn lower_into(
self,
interner: RustInterner<'tcx>,
) -> Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>> {
let (predicate, binders, _named_regions) =
collect_bound_vars(interner, interner.tcx, self.kind());
match predicate {
ty::PredicateKind::Clause(ty::ClauseKind::Trait(predicate)) => {
Some(chalk_ir::Binders::new(
binders,
chalk_solve::rust_ir::InlineBound::TraitBound(
predicate.trait_ref.lower_into(interner),
),
))
}
ty::PredicateKind::Clause(ty::ClauseKind::Projection(predicate)) => {
Some(chalk_ir::Binders::new(
binders,
chalk_solve::rust_ir::InlineBound::AliasEqBound(predicate.lower_into(interner)),
))
}
ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(_predicate)) => None,
ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(_ty)) => None,
ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(..)) => None,
ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(..))
| ty::PredicateKind::AliasRelate(..)
| ty::PredicateKind::ObjectSafe(..)
| ty::PredicateKind::ClosureKind(..)
| ty::PredicateKind::Subtype(..)
| ty::PredicateKind::Coerce(..)
| ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(..))
| ty::PredicateKind::ConstEquate(..)
| ty::PredicateKind::Ambiguous
| ty::PredicateKind::Clause(ty::ClauseKind::TypeWellFormedFromEnv(..)) => {
bug!("unexpected predicate {}", &self)
}
}
}
}
impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::TraitBound<RustInterner<'tcx>>>
for ty::TraitRef<'tcx>
{
fn lower_into(
self,
interner: RustInterner<'tcx>,
) -> chalk_solve::rust_ir::TraitBound<RustInterner<'tcx>> {
chalk_solve::rust_ir::TraitBound {
trait_id: chalk_ir::TraitId(self.def_id),
args_no_self: self.substs[1..].iter().map(|arg| arg.lower_into(interner)).collect(),
}
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::Mutability> for ast::Mutability {
fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_ir::Mutability {
match self {
rustc_ast::Mutability::Mut => chalk_ir::Mutability::Mut,
rustc_ast::Mutability::Not => chalk_ir::Mutability::Not,
}
}
}
impl<'tcx> LowerInto<'tcx, ast::Mutability> for chalk_ir::Mutability {
fn lower_into(self, _interner: RustInterner<'tcx>) -> ast::Mutability {
match self {
chalk_ir::Mutability::Mut => ast::Mutability::Mut,
chalk_ir::Mutability::Not => ast::Mutability::Not,
}
}
}
impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::Polarity> for ty::ImplPolarity {
fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_solve::rust_ir::Polarity {
match self {
ty::ImplPolarity::Positive => chalk_solve::rust_ir::Polarity::Positive,
ty::ImplPolarity::Negative => chalk_solve::rust_ir::Polarity::Negative,
// FIXME(chalk) reservation impls
ty::ImplPolarity::Reservation => chalk_solve::rust_ir::Polarity::Negative,
}
}
}
impl<'tcx> LowerInto<'tcx, chalk_ir::Variance> for ty::Variance {
fn lower_into(self, _interner: RustInterner<'tcx>) -> chalk_ir::Variance {
match self {
ty::Variance::Covariant => chalk_ir::Variance::Covariant,
ty::Variance::Invariant => chalk_ir::Variance::Invariant,
ty::Variance::Contravariant => chalk_ir::Variance::Contravariant,
ty::Variance::Bivariant => unimplemented!(),
}
}
}
impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>>>
for ty::ProjectionPredicate<'tcx>
{
fn lower_into(
self,
interner: RustInterner<'tcx>,
) -> chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>> {
let (trait_ref, own_substs) = self.projection_ty.trait_ref_and_own_substs(interner.tcx);
chalk_solve::rust_ir::AliasEqBound {
trait_bound: trait_ref.lower_into(interner),
associated_ty_id: chalk_ir::AssocTypeId(self.projection_ty.def_id),
parameters: own_substs.iter().map(|arg| arg.lower_into(interner)).collect(),
value: self.term.ty().unwrap().lower_into(interner),
}
}
}
/// To collect bound vars, we have to do two passes. In the first pass, we
/// collect all `BoundRegionKind`s and `ty::Bound`s. In the second pass, we then
/// replace `BrNamed` into `BrAnon`. The two separate passes are important,
/// since we can only replace `BrNamed` with `BrAnon`s with indices *after* all
/// "real" `BrAnon`s.
///
/// It's important to note that because of prior substitution, we may have
/// late-bound regions, even outside of fn contexts, since this is the best way
/// to prep types for chalk lowering.
pub(crate) fn collect_bound_vars<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
interner: RustInterner<'tcx>,
tcx: TyCtxt<'tcx>,
ty: Binder<'tcx, T>,
) -> (T, chalk_ir::VariableKinds<RustInterner<'tcx>>, BTreeMap<DefId, u32>) {
let mut bound_vars_collector = BoundVarsCollector::new();
ty.as_ref().skip_binder().visit_with(&mut bound_vars_collector);
let mut parameters = bound_vars_collector.parameters;
let named_parameters: BTreeMap<DefId, u32> = bound_vars_collector
.named_parameters
.into_iter()
.enumerate()
.map(|(i, def_id)| (def_id, (i + parameters.len()) as u32))
.collect();
let mut bound_var_substitutor = NamedBoundVarSubstitutor::new(tcx, &named_parameters);
let new_ty = ty.skip_binder().fold_with(&mut bound_var_substitutor);
for var in named_parameters.values() {
parameters.insert(*var, chalk_ir::VariableKind::Lifetime);
}
(0..parameters.len()).for_each(|i| {
parameters
.get(&(i as u32))
.or_else(|| bug!("Skipped bound var index: parameters={:?}", parameters));
});
let binders = chalk_ir::VariableKinds::from_iter(interner, parameters.into_values());
(new_ty, binders, named_parameters)
}
pub(crate) struct BoundVarsCollector<'tcx> {
binder_index: ty::DebruijnIndex,
pub(crate) parameters: BTreeMap<u32, chalk_ir::VariableKind<RustInterner<'tcx>>>,
pub(crate) named_parameters: Vec<DefId>,
}
impl<'tcx> BoundVarsCollector<'tcx> {
pub(crate) fn new() -> Self {
BoundVarsCollector {
binder_index: ty::INNERMOST,
parameters: BTreeMap::new(),
named_parameters: vec![],
}
}
}
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for BoundVarsCollector<'tcx> {
fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
&mut self,
t: &Binder<'tcx, T>,
) -> ControlFlow<Self::BreakTy> {
self.binder_index.shift_in(1);
let result = t.super_visit_with(self);
self.binder_index.shift_out(1);
result
}
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
match *t.kind() {
ty::Bound(debruijn, bound_ty) if debruijn == self.binder_index => {
match self.parameters.entry(bound_ty.var.as_u32()) {
Entry::Vacant(entry) => {
entry.insert(chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General));
}
Entry::Occupied(entry) => match entry.get() {
chalk_ir::VariableKind::Ty(_) => {}
_ => panic!(),
},
}
}
_ => (),
};
t.super_visit_with(self)
}
fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> {
match *r {
ty::ReLateBound(index, br) if index == self.binder_index => match br.kind {
ty::BoundRegionKind::BrNamed(def_id, _name) => {
if !self.named_parameters.iter().any(|d| *d == def_id) {
self.named_parameters.push(def_id);
}
}
ty::BoundRegionKind::BrAnon(_) => match self.parameters.entry(br.var.as_u32()) {
Entry::Vacant(entry) => {
entry.insert(chalk_ir::VariableKind::Lifetime);
}
Entry::Occupied(entry) => match entry.get() {
chalk_ir::VariableKind::Lifetime => {}
_ => panic!(),
},
},
ty::BoundRegionKind::BrEnv => unimplemented!(),
},
ty::ReEarlyBound(_re) => {
// FIXME(chalk): jackh726 - I think we should always have already