794 lines
33 KiB
Rust
794 lines
33 KiB
Rust
//! Contains the logic to lower rustc types into Chalk types
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//!
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//! In many cases there is a 1:1 relationship between a rustc type and a Chalk type.
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//! For example, a `SubstsRef` maps almost directly to a `Substitution`. In some
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//! other cases, such as `Param`s, there is no Chalk type, so we have to handle
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//! accordingly.
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//!
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//! ## `Ty` lowering
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//! Much of the `Ty` lowering is 1:1 with Chalk. (Or will be eventually). A
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//! helpful table for what types lower to what can be found in the
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//! [Chalk book](http://rust-lang.github.io/chalk/book/types/rust_types.html).
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//! The most notable difference lies with `Param`s. To convert from rustc to
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//! Chalk, we eagerly and deeply convert `Param`s to placeholders (in goals) or
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//! bound variables (for clause generation through functions in `db`).
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//!
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//! ## `Region` lowering
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//! Regions are handled in rustc and Chalk is quite differently. In rustc, there
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//! is a difference between "early bound" and "late bound" regions, where only
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//! the late bound regions have a `DebruijnIndex`. Moreover, in Chalk all
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//! regions (Lifetimes) have an associated index. In rustc, only `BrAnon`s have
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//! an index, whereas `BrNamed` don't. In order to lower regions to Chalk, we
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//! convert all regions into `BrAnon` late-bound regions.
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//!
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//! ## `Const` lowering
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//! Chalk doesn't handle consts currently, so consts are currently lowered to
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//! an empty tuple.
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//!
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//! ## Bound variable collection
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//! Another difference between rustc and Chalk lies in the handling of binders.
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//! Chalk requires that we store the bound parameter kinds, whereas rustc does
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//! not. To lower anything wrapped in a `Binder`, we first deeply find any bound
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//! variables from the current `Binder`.
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use rustc_middle::traits::{
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ChalkEnvironmentAndGoal, ChalkEnvironmentClause, ChalkRustDefId as RustDefId,
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ChalkRustInterner as RustInterner,
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};
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use rustc_middle::ty::fold::TypeFolder;
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use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
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use rustc_middle::ty::{
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self, Binder, BoundRegion, Region, RegionKind, Ty, TyCtxt, TyKind, TypeFoldable, TypeVisitor,
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};
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use rustc_span::def_id::DefId;
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use std::collections::btree_map::{BTreeMap, Entry};
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/// Essentially an `Into` with a `&RustInterner` parameter
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crate trait LowerInto<'tcx, T> {
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/// Lower a rustc construct (e.g., `ty::TraitPredicate`) to a chalk type, consuming `self`.
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fn lower_into(self, interner: &RustInterner<'tcx>) -> T;
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::Substitution<RustInterner<'tcx>>> for SubstsRef<'tcx> {
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fn lower_into(
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self,
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interner: &RustInterner<'tcx>,
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) -> chalk_ir::Substitution<RustInterner<'tcx>> {
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chalk_ir::Substitution::from(interner, self.iter().map(|s| s.lower_into(interner)))
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::AliasTy<RustInterner<'tcx>>> for ty::ProjectionTy<'tcx> {
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fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::AliasTy<RustInterner<'tcx>> {
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chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
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associated_ty_id: chalk_ir::AssocTypeId(RustDefId::AssocTy(self.item_def_id)),
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substitution: self.substs.lower_into(interner),
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})
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>>>
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for ChalkEnvironmentAndGoal<'tcx>
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{
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fn lower_into(
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self,
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interner: &RustInterner<'tcx>,
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) -> chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>> {
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let clauses = self.environment.into_iter().filter_map(|clause| match clause {
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ChalkEnvironmentClause::Predicate(predicate) => {
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match predicate.kind() {
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ty::PredicateKind::Trait(predicate, _) => {
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let (predicate, binders, _named_regions) =
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collect_bound_vars(interner, interner.tcx, predicate);
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Some(
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chalk_ir::ProgramClauseData::ForAll(chalk_ir::Binders::new(
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binders,
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chalk_ir::ProgramClauseImplication {
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consequence: chalk_ir::DomainGoal::FromEnv(
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chalk_ir::FromEnv::Trait(
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predicate.trait_ref.lower_into(interner),
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),
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),
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conditions: chalk_ir::Goals::new(interner),
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priority: chalk_ir::ClausePriority::High,
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},
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))
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.intern(interner),
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)
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}
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// FIXME(chalk): need to add RegionOutlives/TypeOutlives
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ty::PredicateKind::RegionOutlives(_) => None,
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ty::PredicateKind::TypeOutlives(_) => None,
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ty::PredicateKind::Projection(predicate) => {
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let (predicate, binders, _named_regions) =
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collect_bound_vars(interner, interner.tcx, predicate);
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Some(
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chalk_ir::ProgramClauseData::ForAll(chalk_ir::Binders::new(
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binders,
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chalk_ir::ProgramClauseImplication {
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consequence: chalk_ir::DomainGoal::Holds(
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chalk_ir::WhereClause::AliasEq(
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predicate.lower_into(interner),
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),
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),
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conditions: chalk_ir::Goals::new(interner),
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priority: chalk_ir::ClausePriority::High,
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},
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))
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.intern(interner),
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)
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}
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ty::PredicateKind::WellFormed(..)
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| ty::PredicateKind::ObjectSafe(..)
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| ty::PredicateKind::ClosureKind(..)
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| ty::PredicateKind::Subtype(..)
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| ty::PredicateKind::ConstEvaluatable(..)
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| ty::PredicateKind::ConstEquate(..) => {
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bug!("unexpected predicate {}", predicate)
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}
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}
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}
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ChalkEnvironmentClause::TypeFromEnv(ty) => Some(
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chalk_ir::ProgramClauseData::Implies(chalk_ir::ProgramClauseImplication {
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consequence: chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(
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ty.lower_into(interner),
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)),
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conditions: chalk_ir::Goals::new(interner),
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priority: chalk_ir::ClausePriority::High,
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})
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.intern(interner),
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),
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});
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let goal: chalk_ir::GoalData<RustInterner<'tcx>> = self.goal.lower_into(&interner);
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chalk_ir::InEnvironment {
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environment: chalk_ir::Environment {
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clauses: chalk_ir::ProgramClauses::from(&interner, clauses),
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},
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goal: goal.intern(&interner),
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}
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> for ty::Predicate<'tcx> {
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fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
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match self.kind() {
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ty::PredicateKind::Trait(predicate, _) => predicate.lower_into(interner),
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// FIXME(chalk): we need to register constraints.
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ty::PredicateKind::RegionOutlives(_predicate) => {
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chalk_ir::GoalData::All(chalk_ir::Goals::new(interner))
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}
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ty::PredicateKind::TypeOutlives(_predicate) => {
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chalk_ir::GoalData::All(chalk_ir::Goals::new(interner))
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}
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ty::PredicateKind::Projection(predicate) => predicate.lower_into(interner),
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ty::PredicateKind::WellFormed(arg) => match arg.unpack() {
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GenericArgKind::Type(ty) => match ty.kind {
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// FIXME(chalk): In Chalk, a placeholder is WellFormed if it
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// `FromEnv`. However, when we "lower" Params, we don't update
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// the environment.
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ty::Placeholder(..) => chalk_ir::GoalData::All(chalk_ir::Goals::new(interner)),
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_ => chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::WellFormed(
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chalk_ir::WellFormed::Ty(ty.lower_into(interner)),
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)),
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},
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// FIXME(chalk): handle well formed consts
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GenericArgKind::Const(..) => {
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chalk_ir::GoalData::All(chalk_ir::Goals::new(interner))
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}
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GenericArgKind::Lifetime(lt) => bug!("unexpect well formed predicate: {:?}", lt),
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},
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// FIXME(chalk): other predicates
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//
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// We can defer this, but ultimately we'll want to express
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// some of these in terms of chalk operations.
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ty::PredicateKind::ObjectSafe(..)
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| ty::PredicateKind::ClosureKind(..)
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| ty::PredicateKind::Subtype(..)
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| ty::PredicateKind::ConstEvaluatable(..)
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| ty::PredicateKind::ConstEquate(..) => {
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chalk_ir::GoalData::All(chalk_ir::Goals::new(interner))
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}
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}
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::TraitRef<RustInterner<'tcx>>>
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for rustc_middle::ty::TraitRef<'tcx>
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{
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fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::TraitRef<RustInterner<'tcx>> {
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chalk_ir::TraitRef {
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trait_id: chalk_ir::TraitId(RustDefId::Trait(self.def_id)),
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substitution: self.substs.lower_into(interner),
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}
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>>
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for ty::PolyTraitPredicate<'tcx>
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{
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fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
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let (ty, binders, _named_regions) = collect_bound_vars(interner, interner.tcx, &self);
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chalk_ir::GoalData::Quantified(
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chalk_ir::QuantifierKind::ForAll,
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chalk_ir::Binders::new(
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binders,
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chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
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chalk_ir::WhereClause::Implemented(ty.trait_ref.lower_into(interner)),
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))
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.intern(interner),
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),
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)
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::AliasEq<RustInterner<'tcx>>>
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for rustc_middle::ty::ProjectionPredicate<'tcx>
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{
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fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::AliasEq<RustInterner<'tcx>> {
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chalk_ir::AliasEq {
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ty: self.ty.lower_into(interner),
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alias: self.projection_ty.lower_into(interner),
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}
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>>
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for ty::PolyProjectionPredicate<'tcx>
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{
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fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
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let (ty, binders, _named_regions) = collect_bound_vars(interner, interner.tcx, &self);
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chalk_ir::GoalData::Quantified(
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chalk_ir::QuantifierKind::ForAll,
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chalk_ir::Binders::new(
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binders,
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chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
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chalk_ir::WhereClause::AliasEq(ty.lower_into(interner)),
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))
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.intern(interner),
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),
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)
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> {
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fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Ty<RustInterner<'tcx>> {
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use chalk_ir::TyData;
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use rustc_ast::ast;
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use TyKind::*;
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let empty = || chalk_ir::Substitution::empty(interner);
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let struct_ty = |def_id| chalk_ir::TypeName::Adt(chalk_ir::AdtId(def_id));
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let apply = |name, substitution| {
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TyData::Apply(chalk_ir::ApplicationTy { name, substitution }).intern(interner)
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};
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let int = |i| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Int(i)), empty());
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let uint = |i| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Uint(i)), empty());
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let float = |f| apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Float(f)), empty());
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match self.kind {
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Bool => apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Bool), empty()),
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Char => apply(chalk_ir::TypeName::Scalar(chalk_ir::Scalar::Char), empty()),
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Int(ty) => match ty {
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ast::IntTy::Isize => int(chalk_ir::IntTy::Isize),
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ast::IntTy::I8 => int(chalk_ir::IntTy::I8),
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ast::IntTy::I16 => int(chalk_ir::IntTy::I16),
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ast::IntTy::I32 => int(chalk_ir::IntTy::I32),
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ast::IntTy::I64 => int(chalk_ir::IntTy::I64),
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ast::IntTy::I128 => int(chalk_ir::IntTy::I128),
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},
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Uint(ty) => match ty {
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ast::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
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ast::UintTy::U8 => uint(chalk_ir::UintTy::U8),
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ast::UintTy::U16 => uint(chalk_ir::UintTy::U16),
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ast::UintTy::U32 => uint(chalk_ir::UintTy::U32),
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ast::UintTy::U64 => uint(chalk_ir::UintTy::U64),
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ast::UintTy::U128 => uint(chalk_ir::UintTy::U128),
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},
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Float(ty) => match ty {
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ast::FloatTy::F32 => float(chalk_ir::FloatTy::F32),
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ast::FloatTy::F64 => float(chalk_ir::FloatTy::F64),
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},
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Adt(def, substs) => {
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apply(struct_ty(RustDefId::Adt(def.did)), substs.lower_into(interner))
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}
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Foreign(_def_id) => unimplemented!(),
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Str => apply(chalk_ir::TypeName::Str, empty()),
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Array(ty, _) => apply(
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chalk_ir::TypeName::Array,
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chalk_ir::Substitution::from(
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interner,
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&[
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chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner),
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chalk_ir::GenericArgData::Const(
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chalk_ir::ConstData {
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ty: apply(chalk_ir::TypeName::Tuple(0), empty()),
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value: chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst {
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interned: 0,
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}),
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}
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.intern(interner),
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)
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.intern(interner),
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],
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),
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),
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Slice(ty) => apply(
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chalk_ir::TypeName::Slice,
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chalk_ir::Substitution::from1(
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interner,
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chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner),
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),
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),
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RawPtr(ptr) => {
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let name = match ptr.mutbl {
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ast::Mutability::Mut => chalk_ir::TypeName::Raw(chalk_ir::Mutability::Mut),
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ast::Mutability::Not => chalk_ir::TypeName::Raw(chalk_ir::Mutability::Not),
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};
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apply(name, chalk_ir::Substitution::from1(interner, ptr.ty.lower_into(interner)))
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}
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Ref(region, ty, mutability) => {
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let name = match mutability {
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ast::Mutability::Mut => chalk_ir::TypeName::Ref(chalk_ir::Mutability::Mut),
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ast::Mutability::Not => chalk_ir::TypeName::Ref(chalk_ir::Mutability::Not),
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};
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apply(
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name,
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chalk_ir::Substitution::from(
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interner,
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&[
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chalk_ir::GenericArgData::Lifetime(region.lower_into(interner))
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.intern(interner),
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chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner),
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],
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),
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)
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}
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FnDef(def_id, substs) => apply(
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chalk_ir::TypeName::FnDef(chalk_ir::FnDefId(RustDefId::FnDef(def_id))),
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substs.lower_into(interner),
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),
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FnPtr(sig) => {
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let (inputs_and_outputs, binders, _named_regions) =
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collect_bound_vars(interner, interner.tcx, &sig.inputs_and_output());
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TyData::Function(chalk_ir::Fn {
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num_binders: binders.len(interner),
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substitution: chalk_ir::Substitution::from(
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interner,
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inputs_and_outputs.iter().map(|ty| {
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chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner)
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}),
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),
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})
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.intern(interner)
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}
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// FIXME(chalk): add region
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Dynamic(predicates, _region) => {
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TyData::Dyn(chalk_ir::DynTy { bounds: predicates.lower_into(interner) })
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.intern(interner)
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}
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Closure(_def_id, _) => unimplemented!(),
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Generator(_def_id, _substs, _) => unimplemented!(),
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GeneratorWitness(_) => unimplemented!(),
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Never => apply(chalk_ir::TypeName::Never, empty()),
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Tuple(substs) => {
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apply(chalk_ir::TypeName::Tuple(substs.len()), substs.lower_into(interner))
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}
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Projection(proj) => TyData::Alias(proj.lower_into(interner)).intern(interner),
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Opaque(def_id, substs) => {
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TyData::Alias(chalk_ir::AliasTy::Opaque(chalk_ir::OpaqueTy {
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opaque_ty_id: chalk_ir::OpaqueTyId(RustDefId::Opaque(def_id)),
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substitution: substs.lower_into(interner),
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}))
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.intern(interner)
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}
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// This should have been done eagerly prior to this, and all Params
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// should have been substituted to placeholders
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Param(_) => panic!("Lowering Param when not expected."),
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Bound(db, bound) => TyData::BoundVar(chalk_ir::BoundVar::new(
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chalk_ir::DebruijnIndex::new(db.as_u32()),
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bound.var.index(),
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))
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.intern(interner),
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Placeholder(_placeholder) => TyData::Placeholder(chalk_ir::PlaceholderIndex {
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ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() },
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idx: _placeholder.name.as_usize(),
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})
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.intern(interner),
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Infer(_infer) => unimplemented!(),
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Error(_) => apply(chalk_ir::TypeName::Error, empty()),
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}
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}
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}
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impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'tcx> {
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fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Lifetime<RustInterner<'tcx>> {
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use rustc_middle::ty::RegionKind::*;
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match self {
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ReEarlyBound(_) => {
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|
panic!("Should have already been substituted.");
|
|
}
|
|
ReLateBound(db, br) => match br {
|
|
ty::BoundRegion::BrAnon(var) => {
|
|
chalk_ir::LifetimeData::BoundVar(chalk_ir::BoundVar::new(
|
|
chalk_ir::DebruijnIndex::new(db.as_u32()),
|
|
*var as usize,
|
|
))
|
|
.intern(interner)
|
|
}
|
|
ty::BoundRegion::BrNamed(_def_id, _name) => unimplemented!(),
|
|
ty::BrEnv => unimplemented!(),
|
|
},
|
|
ReFree(_) => unimplemented!(),
|
|
// FIXME(chalk): need to handle ReStatic
|
|
ReStatic => unimplemented!(),
|
|
ReVar(_) => unimplemented!(),
|
|
RePlaceholder(placeholder_region) => {
|
|
chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex {
|
|
ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() },
|
|
idx: 0,
|
|
})
|
|
.intern(interner)
|
|
}
|
|
ReEmpty(_) => unimplemented!(),
|
|
// FIXME(chalk): need to handle ReErased
|
|
ReErased => unimplemented!(),
|
|
}
|
|
}
|
|
}
|
|
|
|
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(_) => chalk_ir::GenericArgData::Ty(
|
|
chalk_ir::TyData::Apply(chalk_ir::ApplicationTy {
|
|
name: chalk_ir::TypeName::Tuple(0),
|
|
substitution: chalk_ir::Substitution::empty(interner),
|
|
})
|
|
.intern(interner),
|
|
),
|
|
}
|
|
.intern(interner)
|
|
}
|
|
}
|
|
|
|
// 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>>> {
|
|
match &self.kind() {
|
|
ty::PredicateKind::Trait(predicate, _) => {
|
|
let (predicate, binders, _named_regions) =
|
|
collect_bound_vars(interner, interner.tcx, predicate);
|
|
|
|
Some(chalk_ir::Binders::new(
|
|
binders,
|
|
chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)),
|
|
))
|
|
}
|
|
ty::PredicateKind::RegionOutlives(_predicate) => None,
|
|
ty::PredicateKind::TypeOutlives(_predicate) => None,
|
|
ty::PredicateKind::Projection(_predicate) => None,
|
|
ty::PredicateKind::WellFormed(_ty) => None,
|
|
|
|
ty::PredicateKind::ObjectSafe(..)
|
|
| ty::PredicateKind::ClosureKind(..)
|
|
| ty::PredicateKind::Subtype(..)
|
|
| ty::PredicateKind::ConstEvaluatable(..)
|
|
| ty::PredicateKind::ConstEquate(..) => bug!("unexpected predicate {}", &self),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>>>
|
|
for Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>
|
|
{
|
|
fn lower_into(
|
|
self,
|
|
interner: &RustInterner<'tcx>,
|
|
) -> chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>> {
|
|
let (predicates, binders, _named_regions) =
|
|
collect_bound_vars(interner, interner.tcx, &self);
|
|
let where_clauses = predicates.into_iter().map(|predicate| match predicate {
|
|
ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef { def_id, substs }) => {
|
|
chalk_ir::Binders::new(
|
|
chalk_ir::VariableKinds::new(interner),
|
|
chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
|
|
trait_id: chalk_ir::TraitId(RustDefId::Trait(*def_id)),
|
|
substitution: substs.lower_into(interner),
|
|
}),
|
|
)
|
|
}
|
|
ty::ExistentialPredicate::Projection(_predicate) => unimplemented!(),
|
|
ty::ExistentialPredicate::AutoTrait(def_id) => chalk_ir::Binders::new(
|
|
chalk_ir::VariableKinds::new(interner),
|
|
chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
|
|
trait_id: chalk_ir::TraitId(RustDefId::Trait(*def_id)),
|
|
substitution: chalk_ir::Substitution::empty(interner),
|
|
}),
|
|
),
|
|
});
|
|
let value = chalk_ir::QuantifiedWhereClauses::from(interner, where_clauses);
|
|
chalk_ir::Binders::new(binders, value)
|
|
}
|
|
}
|
|
|
|
/// To collect bound vars, we have to do two passes. In the first pass, we
|
|
/// collect all `BoundRegion`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.
|
|
crate fn collect_bound_vars<'a, 'tcx, T: TypeFoldable<'tcx>>(
|
|
interner: &RustInterner<'tcx>,
|
|
tcx: TyCtxt<'tcx>,
|
|
ty: &'a Binder<T>,
|
|
) -> (T, chalk_ir::VariableKinds<RustInterner<'tcx>>, BTreeMap<DefId, u32>) {
|
|
let mut bound_vars_collector = BoundVarsCollector::new();
|
|
ty.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)).expect("Skipped bound var index.");
|
|
});
|
|
|
|
let binders = chalk_ir::VariableKinds::from(interner, parameters.into_iter().map(|(_, v)| v));
|
|
|
|
(new_ty, binders, named_parameters)
|
|
}
|
|
|
|
crate struct BoundVarsCollector<'tcx> {
|
|
binder_index: ty::DebruijnIndex,
|
|
crate parameters: BTreeMap<u32, chalk_ir::VariableKind<RustInterner<'tcx>>>,
|
|
crate named_parameters: Vec<DefId>,
|
|
}
|
|
|
|
impl<'tcx> BoundVarsCollector<'tcx> {
|
|
crate fn new() -> Self {
|
|
BoundVarsCollector {
|
|
binder_index: ty::INNERMOST,
|
|
parameters: BTreeMap::new(),
|
|
named_parameters: vec![],
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> TypeVisitor<'tcx> for BoundVarsCollector<'tcx> {
|
|
fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> bool {
|
|
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>) -> bool {
|
|
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::TyKind::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>) -> bool {
|
|
match r {
|
|
ty::ReLateBound(index, br) if *index == self.binder_index => match br {
|
|
ty::BoundRegion::BrNamed(def_id, _name) => {
|
|
if self.named_parameters.iter().find(|d| *d == def_id).is_none() {
|
|
self.named_parameters.push(*def_id);
|
|
}
|
|
}
|
|
|
|
ty::BoundRegion::BrAnon(var) => match self.parameters.entry(*var) {
|
|
Entry::Vacant(entry) => {
|
|
entry.insert(chalk_ir::VariableKind::Lifetime);
|
|
}
|
|
Entry::Occupied(entry) => match entry.get() {
|
|
chalk_ir::VariableKind::Lifetime => {}
|
|
_ => panic!(),
|
|
},
|
|
},
|
|
|
|
ty::BrEnv => unimplemented!(),
|
|
},
|
|
|
|
ty::ReEarlyBound(_re) => {
|
|
// FIXME(chalk): jackh726 - I think we should always have already
|
|
// substituted away `ReEarlyBound`s for `ReLateBound`s, but need to confirm.
|
|
unimplemented!();
|
|
}
|
|
|
|
_ => (),
|
|
};
|
|
|
|
r.super_visit_with(self)
|
|
}
|
|
}
|
|
|
|
/// This is used to replace `BoundRegion::BrNamed` with `BoundRegion::BrAnon`.
|
|
/// Note: we assume that we will always have room for more bound vars. (i.e. we
|
|
/// won't ever hit the `u32` limit in `BrAnon`s).
|
|
struct NamedBoundVarSubstitutor<'a, 'tcx> {
|
|
tcx: TyCtxt<'tcx>,
|
|
binder_index: ty::DebruijnIndex,
|
|
named_parameters: &'a BTreeMap<DefId, u32>,
|
|
}
|
|
|
|
impl<'a, 'tcx> NamedBoundVarSubstitutor<'a, 'tcx> {
|
|
fn new(tcx: TyCtxt<'tcx>, named_parameters: &'a BTreeMap<DefId, u32>) -> Self {
|
|
NamedBoundVarSubstitutor { tcx, binder_index: ty::INNERMOST, named_parameters }
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> TypeFolder<'tcx> for NamedBoundVarSubstitutor<'a, 'tcx> {
|
|
fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
|
|
self.tcx
|
|
}
|
|
|
|
fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> Binder<T> {
|
|
self.binder_index.shift_in(1);
|
|
let result = t.super_fold_with(self);
|
|
self.binder_index.shift_out(1);
|
|
result
|
|
}
|
|
|
|
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
|
|
t.super_fold_with(self)
|
|
}
|
|
|
|
fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
|
|
match r {
|
|
ty::ReLateBound(index, br) if *index == self.binder_index => match br {
|
|
ty::BoundRegion::BrNamed(def_id, _name) => {
|
|
match self.named_parameters.get(def_id) {
|
|
Some(idx) => {
|
|
return self.tcx.mk_region(RegionKind::ReLateBound(
|
|
*index,
|
|
BoundRegion::BrAnon(*idx),
|
|
));
|
|
}
|
|
None => panic!("Missing `BrNamed`."),
|
|
}
|
|
}
|
|
ty::BrEnv => unimplemented!(),
|
|
ty::BoundRegion::BrAnon(_) => {}
|
|
},
|
|
_ => (),
|
|
};
|
|
|
|
r.super_fold_with(self)
|
|
}
|
|
}
|
|
|
|
/// Used to substitute `Param`s with placeholders. We do this since Chalk
|
|
/// have a notion of `Param`s.
|
|
crate struct ParamsSubstitutor<'tcx> {
|
|
tcx: TyCtxt<'tcx>,
|
|
binder_index: ty::DebruijnIndex,
|
|
list: Vec<rustc_middle::ty::ParamTy>,
|
|
crate params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
|
|
crate named_regions: BTreeMap<DefId, u32>,
|
|
}
|
|
|
|
impl<'tcx> ParamsSubstitutor<'tcx> {
|
|
crate fn new(tcx: TyCtxt<'tcx>) -> Self {
|
|
ParamsSubstitutor {
|
|
tcx,
|
|
binder_index: ty::INNERMOST,
|
|
list: vec![],
|
|
params: rustc_data_structures::fx::FxHashMap::default(),
|
|
named_regions: BTreeMap::default(),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
|
|
fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
|
|
self.tcx
|
|
}
|
|
|
|
fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> Binder<T> {
|
|
self.binder_index.shift_in(1);
|
|
let result = t.super_fold_with(self);
|
|
self.binder_index.shift_out(1);
|
|
result
|
|
}
|
|
|
|
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
|
|
match t.kind {
|
|
// FIXME(chalk): currently we convert params to placeholders starting at
|
|
// index `0`. To support placeholders, we'll actually need to do a
|
|
// first pass to collect placeholders. Then we can insert params after.
|
|
ty::Placeholder(_) => unimplemented!(),
|
|
ty::Param(param) => match self.list.iter().position(|r| r == ¶m) {
|
|
Some(_idx) => self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
|
|
universe: ty::UniverseIndex::from_usize(0),
|
|
name: ty::BoundVar::from_usize(_idx),
|
|
})),
|
|
None => {
|
|
self.list.push(param);
|
|
let idx = self.list.len() - 1;
|
|
self.params.insert(idx, param);
|
|
self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
|
|
universe: ty::UniverseIndex::from_usize(0),
|
|
name: ty::BoundVar::from_usize(idx),
|
|
}))
|
|
}
|
|
},
|
|
|
|
_ => t.super_fold_with(self),
|
|
}
|
|
}
|
|
|
|
fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
|
|
match r {
|
|
// FIXME(chalk) - jackh726 - this currently isn't hit in any tests.
|
|
// This covers any region variables in a goal, right?
|
|
ty::ReEarlyBound(_re) => match self.named_regions.get(&_re.def_id) {
|
|
Some(idx) => self.tcx.mk_region(RegionKind::ReLateBound(
|
|
self.binder_index,
|
|
BoundRegion::BrAnon(*idx),
|
|
)),
|
|
None => {
|
|
let idx = self.named_regions.len() as u32;
|
|
self.named_regions.insert(_re.def_id, idx);
|
|
self.tcx.mk_region(RegionKind::ReLateBound(
|
|
self.binder_index,
|
|
BoundRegion::BrAnon(idx),
|
|
))
|
|
}
|
|
},
|
|
|
|
_ => r.super_fold_with(self),
|
|
}
|
|
}
|
|
}
|