1 //! Contains the logic to lower rustc types into Chalk types
3 //! In many cases there is a 1:1 relationship between a rustc type and a Chalk type.
4 //! For example, a `SubstsRef` maps almost directly to a `Substitution`. In some
5 //! other cases, such as `Param`s, there is no Chalk type, so we have to handle
9 //! Much of the `Ty` lowering is 1:1 with Chalk. (Or will be eventually). A
10 //! helpful table for what types lower to what can be found in the
11 //! [Chalk book](http://rust-lang.github.io/chalk/book/types/rust_types.html).
12 //! The most notable difference lies with `Param`s. To convert from rustc to
13 //! Chalk, we eagerly and deeply convert `Param`s to placeholders (in goals) or
14 //! bound variables (for clause generation through functions in `db`).
16 //! ## `Region` lowering
17 //! Regions are handled in rustc and Chalk is quite differently. In rustc, there
18 //! is a difference between "early bound" and "late bound" regions, where only
19 //! the late bound regions have a `DebruijnIndex`. Moreover, in Chalk all
20 //! regions (Lifetimes) have an associated index. In rustc, only `BrAnon`s have
21 //! an index, whereas `BrNamed` don't. In order to lower regions to Chalk, we
22 //! convert all regions into `BrAnon` late-bound regions.
24 //! ## `Const` lowering
25 //! Chalk doesn't handle consts currently, so consts are currently lowered to
28 //! ## Bound variable collection
29 //! Another difference between rustc and Chalk lies in the handling of binders.
30 //! Chalk requires that we store the bound parameter kinds, whereas rustc does
31 //! not. To lower anything wrapped in a `Binder`, we first deeply find any bound
32 //! variables from the current `Binder`.
35 use rustc_middle::traits::{ChalkEnvironmentAndGoal, ChalkRustInterner as RustInterner};
36 use rustc_middle::ty::fold::TypeFolder;
37 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
38 use rustc_middle::ty::{self, Binder, Region, RegionKind, Ty, TyCtxt, TypeFoldable, TypeVisitor};
39 use rustc_span::def_id::DefId;
41 use chalk_ir::{FnSig, ForeignDefId};
42 use rustc_hir::Unsafety;
43 use std::collections::btree_map::{BTreeMap, Entry};
44 use std::ops::ControlFlow;
46 /// Essentially an `Into` with a `&RustInterner` parameter
47 crate trait LowerInto<'tcx, T> {
48 /// Lower a rustc construct (e.g., `ty::TraitPredicate`) to a chalk type, consuming `self`.
49 fn lower_into(self, interner: &RustInterner<'tcx>) -> T;
52 impl<'tcx> LowerInto<'tcx, chalk_ir::Substitution<RustInterner<'tcx>>> for SubstsRef<'tcx> {
55 interner: &RustInterner<'tcx>,
56 ) -> chalk_ir::Substitution<RustInterner<'tcx>> {
57 chalk_ir::Substitution::from_iter(interner, self.iter().map(|s| s.lower_into(interner)))
61 impl<'tcx> LowerInto<'tcx, SubstsRef<'tcx>> for &chalk_ir::Substitution<RustInterner<'tcx>> {
62 fn lower_into(self, interner: &RustInterner<'tcx>) -> SubstsRef<'tcx> {
63 interner.tcx.mk_substs(self.iter(interner).map(|subst| subst.lower_into(interner)))
67 impl<'tcx> LowerInto<'tcx, chalk_ir::AliasTy<RustInterner<'tcx>>> for ty::ProjectionTy<'tcx> {
68 fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::AliasTy<RustInterner<'tcx>> {
69 chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
70 associated_ty_id: chalk_ir::AssocTypeId(self.item_def_id),
71 substitution: self.substs.lower_into(interner),
76 impl<'tcx> LowerInto<'tcx, chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>>>
77 for ChalkEnvironmentAndGoal<'tcx>
81 interner: &RustInterner<'tcx>,
82 ) -> chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>> {
83 let clauses = self.environment.into_iter().map(|predicate| {
84 let (predicate, binders, _named_regions) =
85 collect_bound_vars(interner, interner.tcx, predicate.kind());
86 let consequence = match predicate {
87 ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
88 chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(ty.lower_into(interner)))
90 ty::PredicateKind::Trait(predicate, _) => chalk_ir::DomainGoal::FromEnv(
91 chalk_ir::FromEnv::Trait(predicate.trait_ref.lower_into(interner)),
93 ty::PredicateKind::RegionOutlives(predicate) => chalk_ir::DomainGoal::Holds(
94 chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
95 a: predicate.0.lower_into(interner),
96 b: predicate.1.lower_into(interner),
99 ty::PredicateKind::TypeOutlives(predicate) => chalk_ir::DomainGoal::Holds(
100 chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
101 ty: predicate.0.lower_into(interner),
102 lifetime: predicate.1.lower_into(interner),
105 ty::PredicateKind::Projection(predicate) => chalk_ir::DomainGoal::Holds(
106 chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)),
108 ty::PredicateKind::WellFormed(..)
109 | ty::PredicateKind::ObjectSafe(..)
110 | ty::PredicateKind::ClosureKind(..)
111 | ty::PredicateKind::Subtype(..)
112 | ty::PredicateKind::ConstEvaluatable(..)
113 | ty::PredicateKind::ConstEquate(..) => bug!("unexpected predicate {}", predicate),
115 let value = chalk_ir::ProgramClauseImplication {
117 conditions: chalk_ir::Goals::empty(interner),
118 priority: chalk_ir::ClausePriority::High,
119 constraints: chalk_ir::Constraints::empty(interner),
121 chalk_ir::ProgramClauseData(chalk_ir::Binders::new(binders, value)).intern(interner)
124 let goal: chalk_ir::GoalData<RustInterner<'tcx>> = self.goal.lower_into(&interner);
125 chalk_ir::InEnvironment {
126 environment: chalk_ir::Environment {
127 clauses: chalk_ir::ProgramClauses::from_iter(&interner, clauses),
129 goal: goal.intern(&interner),
134 impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> for ty::Predicate<'tcx> {
135 fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
136 let (predicate, binders, _named_regions) =
137 collect_bound_vars(interner, interner.tcx, self.kind());
139 let value = match predicate {
140 ty::PredicateKind::Trait(predicate, _) => {
141 chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
142 chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)),
145 ty::PredicateKind::RegionOutlives(predicate) => {
146 chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
147 chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
148 a: predicate.0.lower_into(interner),
149 b: predicate.1.lower_into(interner),
153 ty::PredicateKind::TypeOutlives(predicate) => {
154 chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
155 chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
156 ty: predicate.0.lower_into(interner),
157 lifetime: predicate.1.lower_into(interner),
161 ty::PredicateKind::Projection(predicate) => {
162 chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(
163 chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)),
166 ty::PredicateKind::WellFormed(arg) => match arg.unpack() {
167 GenericArgKind::Type(ty) => match ty.kind() {
168 // FIXME(chalk): In Chalk, a placeholder is WellFormed if it
169 // `FromEnv`. However, when we "lower" Params, we don't update
171 ty::Placeholder(..) => {
172 chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner))
175 _ => chalk_ir::GoalData::DomainGoal(chalk_ir::DomainGoal::WellFormed(
176 chalk_ir::WellFormed::Ty(ty.lower_into(interner)),
179 // FIXME(chalk): handle well formed consts
180 GenericArgKind::Const(..) => {
181 chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner))
183 GenericArgKind::Lifetime(lt) => bug!("unexpect well formed predicate: {:?}", lt),
186 ty::PredicateKind::ObjectSafe(t) => chalk_ir::GoalData::DomainGoal(
187 chalk_ir::DomainGoal::ObjectSafe(chalk_ir::TraitId(t)),
190 // FIXME(chalk): other predicates
192 // We can defer this, but ultimately we'll want to express
193 // some of these in terms of chalk operations.
194 ty::PredicateKind::ClosureKind(..)
195 | ty::PredicateKind::Subtype(..)
196 | ty::PredicateKind::ConstEvaluatable(..)
197 | ty::PredicateKind::ConstEquate(..) => {
198 chalk_ir::GoalData::All(chalk_ir::Goals::empty(interner))
200 ty::PredicateKind::TypeWellFormedFromEnv(ty) => chalk_ir::GoalData::DomainGoal(
201 chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(ty.lower_into(interner))),
205 chalk_ir::GoalData::Quantified(
206 chalk_ir::QuantifierKind::ForAll,
207 chalk_ir::Binders::new(binders, value.intern(interner)),
212 impl<'tcx> LowerInto<'tcx, chalk_ir::TraitRef<RustInterner<'tcx>>>
213 for rustc_middle::ty::TraitRef<'tcx>
215 fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::TraitRef<RustInterner<'tcx>> {
217 trait_id: chalk_ir::TraitId(self.def_id),
218 substitution: self.substs.lower_into(interner),
223 impl<'tcx> LowerInto<'tcx, chalk_ir::AliasEq<RustInterner<'tcx>>>
224 for rustc_middle::ty::ProjectionPredicate<'tcx>
226 fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::AliasEq<RustInterner<'tcx>> {
228 ty: self.ty.lower_into(interner),
229 alias: self.projection_ty.lower_into(interner),
234 impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> {
235 fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Ty<RustInterner<'tcx>> {
236 let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i));
237 let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i));
238 let float = |f| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Float(f));
241 ty::Bool => chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Bool),
242 ty::Char => chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Char),
243 ty::Int(ty) => match ty {
244 ty::IntTy::Isize => int(chalk_ir::IntTy::Isize),
245 ty::IntTy::I8 => int(chalk_ir::IntTy::I8),
246 ty::IntTy::I16 => int(chalk_ir::IntTy::I16),
247 ty::IntTy::I32 => int(chalk_ir::IntTy::I32),
248 ty::IntTy::I64 => int(chalk_ir::IntTy::I64),
249 ty::IntTy::I128 => int(chalk_ir::IntTy::I128),
251 ty::Uint(ty) => match ty {
252 ty::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
253 ty::UintTy::U8 => uint(chalk_ir::UintTy::U8),
254 ty::UintTy::U16 => uint(chalk_ir::UintTy::U16),
255 ty::UintTy::U32 => uint(chalk_ir::UintTy::U32),
256 ty::UintTy::U64 => uint(chalk_ir::UintTy::U64),
257 ty::UintTy::U128 => uint(chalk_ir::UintTy::U128),
259 ty::Float(ty) => match ty {
260 ty::FloatTy::F32 => float(chalk_ir::FloatTy::F32),
261 ty::FloatTy::F64 => float(chalk_ir::FloatTy::F64),
263 ty::Adt(def, substs) => {
264 chalk_ir::TyKind::Adt(chalk_ir::AdtId(def), substs.lower_into(interner))
266 ty::Foreign(def_id) => chalk_ir::TyKind::Foreign(ForeignDefId(def_id)),
267 ty::Str => chalk_ir::TyKind::Str,
268 ty::Array(ty, len) => {
269 chalk_ir::TyKind::Array(ty.lower_into(interner), len.lower_into(interner))
271 ty::Slice(ty) => chalk_ir::TyKind::Slice(ty.lower_into(interner)),
274 chalk_ir::TyKind::Raw(ptr.mutbl.lower_into(interner), ptr.ty.lower_into(interner))
276 ty::Ref(region, ty, mutability) => chalk_ir::TyKind::Ref(
277 mutability.lower_into(interner),
278 region.lower_into(interner),
279 ty.lower_into(interner),
281 ty::FnDef(def_id, substs) => {
282 chalk_ir::TyKind::FnDef(chalk_ir::FnDefId(def_id), substs.lower_into(interner))
285 let (inputs_and_outputs, binders, _named_regions) =
286 collect_bound_vars(interner, interner.tcx, sig.inputs_and_output());
287 chalk_ir::TyKind::Function(chalk_ir::FnPointer {
288 num_binders: binders.len(interner),
289 sig: sig.lower_into(interner),
290 substitution: chalk_ir::FnSubst(chalk_ir::Substitution::from_iter(
292 inputs_and_outputs.iter().map(|ty| {
293 chalk_ir::GenericArgData::Ty(ty.lower_into(interner)).intern(interner)
298 ty::Dynamic(predicates, region) => chalk_ir::TyKind::Dyn(chalk_ir::DynTy {
299 bounds: predicates.lower_into(interner),
300 lifetime: region.lower_into(interner),
302 ty::Closure(def_id, substs) => {
303 chalk_ir::TyKind::Closure(chalk_ir::ClosureId(def_id), substs.lower_into(interner))
305 ty::Generator(_def_id, _substs, _) => unimplemented!(),
306 ty::GeneratorWitness(_) => unimplemented!(),
307 ty::Never => chalk_ir::TyKind::Never,
308 ty::Tuple(substs) => chalk_ir::TyKind::Tuple(substs.len(), substs.lower_into(interner)),
309 ty::Projection(proj) => chalk_ir::TyKind::Alias(proj.lower_into(interner)),
310 ty::Opaque(def_id, substs) => {
311 chalk_ir::TyKind::Alias(chalk_ir::AliasTy::Opaque(chalk_ir::OpaqueTy {
312 opaque_ty_id: chalk_ir::OpaqueTyId(def_id),
313 substitution: substs.lower_into(interner),
316 // This should have been done eagerly prior to this, and all Params
317 // should have been substituted to placeholders
318 ty::Param(_) => panic!("Lowering Param when not expected."),
319 ty::Bound(db, bound) => chalk_ir::TyKind::BoundVar(chalk_ir::BoundVar::new(
320 chalk_ir::DebruijnIndex::new(db.as_u32()),
323 ty::Placeholder(_placeholder) => {
324 chalk_ir::TyKind::Placeholder(chalk_ir::PlaceholderIndex {
325 ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() },
326 idx: _placeholder.name.as_usize(),
329 ty::Infer(_infer) => unimplemented!(),
330 ty::Error(_) => chalk_ir::TyKind::Error,
336 impl<'tcx> LowerInto<'tcx, Ty<'tcx>> for &chalk_ir::Ty<RustInterner<'tcx>> {
337 fn lower_into(self, interner: &RustInterner<'tcx>) -> Ty<'tcx> {
338 use chalk_ir::TyKind;
340 let kind = match self.kind(interner) {
341 TyKind::Adt(struct_id, substitution) => {
342 ty::Adt(struct_id.0, substitution.lower_into(interner))
344 TyKind::Scalar(scalar) => match scalar {
345 chalk_ir::Scalar::Bool => ty::Bool,
346 chalk_ir::Scalar::Char => ty::Char,
347 chalk_ir::Scalar::Int(int_ty) => match int_ty {
348 chalk_ir::IntTy::Isize => ty::Int(ty::IntTy::Isize),
349 chalk_ir::IntTy::I8 => ty::Int(ty::IntTy::I8),
350 chalk_ir::IntTy::I16 => ty::Int(ty::IntTy::I16),
351 chalk_ir::IntTy::I32 => ty::Int(ty::IntTy::I32),
352 chalk_ir::IntTy::I64 => ty::Int(ty::IntTy::I64),
353 chalk_ir::IntTy::I128 => ty::Int(ty::IntTy::I128),
355 chalk_ir::Scalar::Uint(int_ty) => match int_ty {
356 chalk_ir::UintTy::Usize => ty::Uint(ty::UintTy::Usize),
357 chalk_ir::UintTy::U8 => ty::Uint(ty::UintTy::U8),
358 chalk_ir::UintTy::U16 => ty::Uint(ty::UintTy::U16),
359 chalk_ir::UintTy::U32 => ty::Uint(ty::UintTy::U32),
360 chalk_ir::UintTy::U64 => ty::Uint(ty::UintTy::U64),
361 chalk_ir::UintTy::U128 => ty::Uint(ty::UintTy::U128),
363 chalk_ir::Scalar::Float(float_ty) => match float_ty {
364 chalk_ir::FloatTy::F32 => ty::Float(ty::FloatTy::F32),
365 chalk_ir::FloatTy::F64 => ty::Float(ty::FloatTy::F64),
368 TyKind::Array(ty, c) => {
369 let ty = ty.lower_into(interner);
370 let c = c.lower_into(interner);
371 ty::Array(ty, interner.tcx.mk_const(c))
373 TyKind::FnDef(id, substitution) => ty::FnDef(id.0, substitution.lower_into(interner)),
374 TyKind::Closure(closure, substitution) => {
375 ty::Closure(closure.0, substitution.lower_into(interner))
377 TyKind::Generator(..) => unimplemented!(),
378 TyKind::GeneratorWitness(..) => unimplemented!(),
379 TyKind::Never => ty::Never,
380 TyKind::Tuple(_len, substitution) => ty::Tuple(substitution.lower_into(interner)),
381 TyKind::Slice(ty) => ty::Slice(ty.lower_into(interner)),
382 TyKind::Raw(mutbl, ty) => ty::RawPtr(ty::TypeAndMut {
383 ty: ty.lower_into(interner),
384 mutbl: mutbl.lower_into(interner),
386 TyKind::Ref(mutbl, lifetime, ty) => ty::Ref(
387 lifetime.lower_into(interner),
388 ty.lower_into(interner),
389 mutbl.lower_into(interner),
391 TyKind::Str => ty::Str,
392 TyKind::OpaqueType(opaque_ty, substitution) => {
393 ty::Opaque(opaque_ty.0, substitution.lower_into(interner))
395 TyKind::AssociatedType(assoc_ty, substitution) => ty::Projection(ty::ProjectionTy {
396 substs: substitution.lower_into(interner),
397 item_def_id: assoc_ty.0,
399 TyKind::Foreign(def_id) => ty::Foreign(def_id.0),
400 TyKind::Error => return interner.tcx.ty_error(),
401 TyKind::Placeholder(placeholder) => ty::Placeholder(ty::Placeholder {
402 universe: ty::UniverseIndex::from_usize(placeholder.ui.counter),
403 name: ty::BoundVar::from_usize(placeholder.idx),
405 TyKind::Alias(alias_ty) => match alias_ty {
406 chalk_ir::AliasTy::Projection(projection) => ty::Projection(ty::ProjectionTy {
407 item_def_id: projection.associated_ty_id.0,
408 substs: projection.substitution.lower_into(interner),
410 chalk_ir::AliasTy::Opaque(opaque) => {
411 ty::Opaque(opaque.opaque_ty_id.0, opaque.substitution.lower_into(interner))
414 TyKind::Function(_quantified_ty) => unimplemented!(),
415 TyKind::BoundVar(_bound) => ty::Bound(
416 ty::DebruijnIndex::from_usize(_bound.debruijn.depth() as usize),
418 var: ty::BoundVar::from_usize(_bound.index),
419 kind: ty::BoundTyKind::Anon,
422 TyKind::InferenceVar(_, _) => unimplemented!(),
423 TyKind::Dyn(_) => unimplemented!(),
425 interner.tcx.mk_ty(kind)
429 impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'tcx> {
430 fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Lifetime<RustInterner<'tcx>> {
431 use rustc_middle::ty::RegionKind::*;
435 panic!("Should have already been substituted.");
437 ReLateBound(db, br) => match br.kind {
438 ty::BoundRegionKind::BrAnon(var) => {
439 chalk_ir::LifetimeData::BoundVar(chalk_ir::BoundVar::new(
440 chalk_ir::DebruijnIndex::new(db.as_u32()),
445 ty::BoundRegionKind::BrNamed(_def_id, _name) => unimplemented!(),
446 ty::BrEnv => unimplemented!(),
448 ReFree(_) => unimplemented!(),
449 ReStatic => chalk_ir::LifetimeData::Static.intern(interner),
450 ReVar(_) => unimplemented!(),
451 RePlaceholder(placeholder_region) => {
452 chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex {
453 ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() },
458 ReEmpty(_) => unimplemented!(),
459 // FIXME(chalk): need to handle ReErased
460 ReErased => unimplemented!(),
465 impl<'tcx> LowerInto<'tcx, Region<'tcx>> for &chalk_ir::Lifetime<RustInterner<'tcx>> {
466 fn lower_into(self, interner: &RustInterner<'tcx>) -> Region<'tcx> {
467 let kind = match self.data(interner) {
468 chalk_ir::LifetimeData::BoundVar(var) => ty::RegionKind::ReLateBound(
469 ty::DebruijnIndex::from_u32(var.debruijn.depth()),
470 ty::BoundRegion { kind: ty::BrAnon(var.index as u32) },
472 chalk_ir::LifetimeData::InferenceVar(_var) => unimplemented!(),
473 chalk_ir::LifetimeData::Placeholder(p) => {
474 ty::RegionKind::RePlaceholder(ty::Placeholder {
475 universe: ty::UniverseIndex::from_usize(p.ui.counter),
476 name: ty::BoundRegionKind::BrAnon(p.idx as u32),
479 chalk_ir::LifetimeData::Static => ty::RegionKind::ReStatic,
480 chalk_ir::LifetimeData::Phantom(_, _) => unimplemented!(),
481 chalk_ir::LifetimeData::Empty(ui) => {
482 ty::RegionKind::ReEmpty(ty::UniverseIndex::from_usize(ui.counter))
484 chalk_ir::LifetimeData::Erased => ty::RegionKind::ReErased,
486 interner.tcx.mk_region(kind)
490 impl<'tcx> LowerInto<'tcx, chalk_ir::Const<RustInterner<'tcx>>> for ty::Const<'tcx> {
491 fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::Const<RustInterner<'tcx>> {
492 let ty = self.ty.lower_into(interner);
493 let value = match self.val {
494 ty::ConstKind::Value(val) => {
495 chalk_ir::ConstValue::Concrete(chalk_ir::ConcreteConst { interned: val })
497 ty::ConstKind::Bound(db, bound) => chalk_ir::ConstValue::BoundVar(
498 chalk_ir::BoundVar::new(chalk_ir::DebruijnIndex::new(db.as_u32()), bound.index()),
500 _ => unimplemented!("Const not implemented. {:?}", self),
502 chalk_ir::ConstData { ty, value }.intern(interner)
506 impl<'tcx> LowerInto<'tcx, ty::Const<'tcx>> for &chalk_ir::Const<RustInterner<'tcx>> {
507 fn lower_into(self, interner: &RustInterner<'tcx>) -> ty::Const<'tcx> {
508 let data = self.data(interner);
509 let ty = data.ty.lower_into(interner);
510 let val = match data.value {
511 chalk_ir::ConstValue::BoundVar(var) => ty::ConstKind::Bound(
512 ty::DebruijnIndex::from_u32(var.debruijn.depth()),
513 ty::BoundVar::from_u32(var.index as u32),
515 chalk_ir::ConstValue::InferenceVar(_var) => unimplemented!(),
516 chalk_ir::ConstValue::Placeholder(_p) => unimplemented!(),
517 chalk_ir::ConstValue::Concrete(c) => ty::ConstKind::Value(c.interned),
519 ty::Const { ty, val }
523 impl<'tcx> LowerInto<'tcx, chalk_ir::GenericArg<RustInterner<'tcx>>> for GenericArg<'tcx> {
524 fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GenericArg<RustInterner<'tcx>> {
525 match self.unpack() {
526 ty::subst::GenericArgKind::Type(ty) => {
527 chalk_ir::GenericArgData::Ty(ty.lower_into(interner))
529 ty::subst::GenericArgKind::Lifetime(lifetime) => {
530 chalk_ir::GenericArgData::Lifetime(lifetime.lower_into(interner))
532 ty::subst::GenericArgKind::Const(c) => {
533 chalk_ir::GenericArgData::Const(c.lower_into(interner))
540 impl<'tcx> LowerInto<'tcx, ty::subst::GenericArg<'tcx>>
541 for &chalk_ir::GenericArg<RustInterner<'tcx>>
543 fn lower_into(self, interner: &RustInterner<'tcx>) -> ty::subst::GenericArg<'tcx> {
544 match self.data(interner) {
545 chalk_ir::GenericArgData::Ty(ty) => {
546 let t: Ty<'tcx> = ty.lower_into(interner);
549 chalk_ir::GenericArgData::Lifetime(lifetime) => {
550 let r: Region<'tcx> = lifetime.lower_into(interner);
553 chalk_ir::GenericArgData::Const(c) => {
554 let c: ty::Const<'tcx> = c.lower_into(interner);
555 interner.tcx.mk_const(c).into()
561 // We lower into an Option here since there are some predicates which Chalk
562 // doesn't have a representation for yet (as a `WhereClause`), but are so common
563 // that we just are accepting the unsoundness for now. The `Option` will
564 // eventually be removed.
565 impl<'tcx> LowerInto<'tcx, Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>
566 for ty::Predicate<'tcx>
570 interner: &RustInterner<'tcx>,
571 ) -> Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> {
572 let (predicate, binders, _named_regions) =
573 collect_bound_vars(interner, interner.tcx, self.kind());
574 let value = match predicate {
575 ty::PredicateKind::Trait(predicate, _) => {
576 Some(chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)))
578 ty::PredicateKind::RegionOutlives(predicate) => {
579 Some(chalk_ir::WhereClause::LifetimeOutlives(chalk_ir::LifetimeOutlives {
580 a: predicate.0.lower_into(interner),
581 b: predicate.1.lower_into(interner),
584 ty::PredicateKind::TypeOutlives(predicate) => {
585 Some(chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
586 ty: predicate.0.lower_into(interner),
587 lifetime: predicate.1.lower_into(interner),
590 ty::PredicateKind::Projection(predicate) => {
591 Some(chalk_ir::WhereClause::AliasEq(predicate.lower_into(interner)))
593 ty::PredicateKind::WellFormed(_ty) => None,
595 ty::PredicateKind::ObjectSafe(..)
596 | ty::PredicateKind::ClosureKind(..)
597 | ty::PredicateKind::Subtype(..)
598 | ty::PredicateKind::ConstEvaluatable(..)
599 | ty::PredicateKind::ConstEquate(..)
600 | ty::PredicateKind::TypeWellFormedFromEnv(..) => {
601 bug!("unexpected predicate {}", &self)
604 value.map(|value| chalk_ir::Binders::new(binders, value))
608 impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>>>
609 for &'tcx ty::List<ty::Binder<ty::ExistentialPredicate<'tcx>>>
613 interner: &RustInterner<'tcx>,
614 ) -> chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<RustInterner<'tcx>>> {
615 // `Self` has one binder:
616 // Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>
617 // The return type has two:
618 // Binders<&[Binders<WhereClause<I>>]>
619 // This means that any variables that are escaping `self` need to be
620 // shifted in by one so that they are still escaping.
621 let predicates = ty::fold::shift_vars(interner.tcx, self, 1);
623 let self_ty = interner.tcx.mk_ty(ty::Bound(
624 // This is going to be wrapped in a binder
625 ty::DebruijnIndex::from_usize(1),
626 ty::BoundTy { var: ty::BoundVar::from_usize(0), kind: ty::BoundTyKind::Anon },
628 let where_clauses = predicates.into_iter().map(|predicate| {
629 let (predicate, binders, _named_regions) =
630 collect_bound_vars(interner, interner.tcx, predicate);
632 ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef { def_id, substs }) => {
633 chalk_ir::Binders::new(
635 chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
636 trait_id: chalk_ir::TraitId(def_id),
637 substitution: interner
639 .mk_substs_trait(self_ty, substs)
640 .lower_into(interner),
644 ty::ExistentialPredicate::Projection(predicate) => chalk_ir::Binders::new(
646 chalk_ir::WhereClause::AliasEq(chalk_ir::AliasEq {
647 alias: chalk_ir::AliasTy::Projection(chalk_ir::ProjectionTy {
648 associated_ty_id: chalk_ir::AssocTypeId(predicate.item_def_id),
649 substitution: interner
651 .mk_substs_trait(self_ty, predicate.substs)
652 .lower_into(interner),
654 ty: predicate.ty.lower_into(interner),
657 ty::ExistentialPredicate::AutoTrait(def_id) => chalk_ir::Binders::new(
659 chalk_ir::WhereClause::Implemented(chalk_ir::TraitRef {
660 trait_id: chalk_ir::TraitId(def_id),
661 substitution: interner
663 .mk_substs_trait(self_ty, &[])
664 .lower_into(interner),
670 // Binder for the bound variable representing the concrete underlying type.
671 let existential_binder = chalk_ir::VariableKinds::from1(
673 chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
675 let value = chalk_ir::QuantifiedWhereClauses::from_iter(interner, where_clauses);
676 chalk_ir::Binders::new(existential_binder, value)
680 impl<'tcx> LowerInto<'tcx, chalk_ir::FnSig<RustInterner<'tcx>>> for ty::Binder<ty::FnSig<'tcx>> {
681 fn lower_into(self, _interner: &RustInterner<'_>) -> FnSig<RustInterner<'tcx>> {
684 safety: match self.unsafety() {
685 Unsafety::Normal => chalk_ir::Safety::Safe,
686 Unsafety::Unsafe => chalk_ir::Safety::Unsafe,
688 variadic: self.c_variadic(),
693 // We lower into an Option here since there are some predicates which Chalk
694 // doesn't have a representation for yet (as an `InlineBound`). The `Option` will
695 // eventually be removed.
696 impl<'tcx> LowerInto<'tcx, Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>>>
697 for ty::Predicate<'tcx>
701 interner: &RustInterner<'tcx>,
702 ) -> Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>> {
703 let (predicate, binders, _named_regions) =
704 collect_bound_vars(interner, interner.tcx, self.kind());
706 ty::PredicateKind::Trait(predicate, _) => Some(chalk_ir::Binders::new(
708 chalk_solve::rust_ir::InlineBound::TraitBound(
709 predicate.trait_ref.lower_into(interner),
712 ty::PredicateKind::Projection(predicate) => Some(chalk_ir::Binders::new(
714 chalk_solve::rust_ir::InlineBound::AliasEqBound(predicate.lower_into(interner)),
716 ty::PredicateKind::TypeOutlives(_predicate) => None,
717 ty::PredicateKind::WellFormed(_ty) => None,
719 ty::PredicateKind::RegionOutlives(..)
720 | ty::PredicateKind::ObjectSafe(..)
721 | ty::PredicateKind::ClosureKind(..)
722 | ty::PredicateKind::Subtype(..)
723 | ty::PredicateKind::ConstEvaluatable(..)
724 | ty::PredicateKind::ConstEquate(..)
725 | ty::PredicateKind::TypeWellFormedFromEnv(..) => {
726 bug!("unexpected predicate {}", &self)
732 impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::TraitBound<RustInterner<'tcx>>>
733 for ty::TraitRef<'tcx>
737 interner: &RustInterner<'tcx>,
738 ) -> chalk_solve::rust_ir::TraitBound<RustInterner<'tcx>> {
739 chalk_solve::rust_ir::TraitBound {
740 trait_id: chalk_ir::TraitId(self.def_id),
741 args_no_self: self.substs[1..].iter().map(|arg| arg.lower_into(interner)).collect(),
746 impl<'tcx> LowerInto<'tcx, chalk_ir::Mutability> for ast::Mutability {
747 fn lower_into(self, _interner: &RustInterner<'tcx>) -> chalk_ir::Mutability {
749 rustc_ast::Mutability::Mut => chalk_ir::Mutability::Mut,
750 rustc_ast::Mutability::Not => chalk_ir::Mutability::Not,
755 impl<'tcx> LowerInto<'tcx, ast::Mutability> for chalk_ir::Mutability {
756 fn lower_into(self, _interner: &RustInterner<'tcx>) -> ast::Mutability {
758 chalk_ir::Mutability::Mut => ast::Mutability::Mut,
759 chalk_ir::Mutability::Not => ast::Mutability::Not,
764 impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::Polarity> for ty::ImplPolarity {
765 fn lower_into(self, _interner: &RustInterner<'tcx>) -> chalk_solve::rust_ir::Polarity {
767 ty::ImplPolarity::Positive => chalk_solve::rust_ir::Polarity::Positive,
768 ty::ImplPolarity::Negative => chalk_solve::rust_ir::Polarity::Negative,
769 // FIXME(chalk) reservation impls
770 ty::ImplPolarity::Reservation => chalk_solve::rust_ir::Polarity::Negative,
775 impl<'tcx> LowerInto<'tcx, chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>>>
776 for ty::ProjectionPredicate<'tcx>
780 interner: &RustInterner<'tcx>,
781 ) -> chalk_solve::rust_ir::AliasEqBound<RustInterner<'tcx>> {
782 let (trait_ref, own_substs) = self.projection_ty.trait_ref_and_own_substs(interner.tcx);
783 chalk_solve::rust_ir::AliasEqBound {
784 trait_bound: trait_ref.lower_into(interner),
785 associated_ty_id: chalk_ir::AssocTypeId(self.projection_ty.item_def_id),
786 parameters: own_substs.iter().map(|arg| arg.lower_into(interner)).collect(),
787 value: self.ty.lower_into(interner),
792 /// To collect bound vars, we have to do two passes. In the first pass, we
793 /// collect all `BoundRegionKind`s and `ty::Bound`s. In the second pass, we then
794 /// replace `BrNamed` into `BrAnon`. The two separate passes are important,
795 /// since we can only replace `BrNamed` with `BrAnon`s with indices *after* all
796 /// "real" `BrAnon`s.
798 /// It's important to note that because of prior substitution, we may have
799 /// late-bound regions, even outside of fn contexts, since this is the best way
800 /// to prep types for chalk lowering.
801 crate fn collect_bound_vars<'tcx, T: TypeFoldable<'tcx>>(
802 interner: &RustInterner<'tcx>,
805 ) -> (T, chalk_ir::VariableKinds<RustInterner<'tcx>>, BTreeMap<DefId, u32>) {
806 let mut bound_vars_collector = BoundVarsCollector::new();
807 ty.as_ref().skip_binder().visit_with(&mut bound_vars_collector);
808 let mut parameters = bound_vars_collector.parameters;
809 let named_parameters: BTreeMap<DefId, u32> = bound_vars_collector
813 .map(|(i, def_id)| (def_id, (i + parameters.len()) as u32))
816 let mut bound_var_substitutor = NamedBoundVarSubstitutor::new(tcx, &named_parameters);
817 let new_ty = ty.skip_binder().fold_with(&mut bound_var_substitutor);
819 for var in named_parameters.values() {
820 parameters.insert(*var, chalk_ir::VariableKind::Lifetime);
823 (0..parameters.len()).for_each(|i| {
826 .or_else(|| bug!("Skipped bound var index: parameters={:?}", parameters));
830 chalk_ir::VariableKinds::from_iter(interner, parameters.into_iter().map(|(_, v)| v));
832 (new_ty, binders, named_parameters)
835 crate struct BoundVarsCollector<'tcx> {
836 binder_index: ty::DebruijnIndex,
837 crate parameters: BTreeMap<u32, chalk_ir::VariableKind<RustInterner<'tcx>>>,
838 crate named_parameters: Vec<DefId>,
841 impl<'tcx> BoundVarsCollector<'tcx> {
842 crate fn new() -> Self {
844 binder_index: ty::INNERMOST,
845 parameters: BTreeMap::new(),
846 named_parameters: vec![],
851 impl<'tcx> TypeVisitor<'tcx> for BoundVarsCollector<'tcx> {
852 fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, t: &Binder<T>) -> ControlFlow<Self::BreakTy> {
853 self.binder_index.shift_in(1);
854 let result = t.super_visit_with(self);
855 self.binder_index.shift_out(1);
859 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
861 ty::Bound(debruijn, bound_ty) if debruijn == self.binder_index => {
862 match self.parameters.entry(bound_ty.var.as_u32()) {
863 Entry::Vacant(entry) => {
864 entry.insert(chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General));
866 Entry::Occupied(entry) => match entry.get() {
867 chalk_ir::VariableKind::Ty(_) => {}
876 t.super_visit_with(self)
879 fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> {
881 ty::ReLateBound(index, br) if *index == self.binder_index => match br.kind {
882 ty::BoundRegionKind::BrNamed(def_id, _name) => {
883 if self.named_parameters.iter().find(|d| **d == def_id).is_none() {
884 self.named_parameters.push(def_id);
888 ty::BoundRegionKind::BrAnon(var) => match self.parameters.entry(var) {
889 Entry::Vacant(entry) => {
890 entry.insert(chalk_ir::VariableKind::Lifetime);
892 Entry::Occupied(entry) => match entry.get() {
893 chalk_ir::VariableKind::Lifetime => {}
898 ty::BrEnv => unimplemented!(),
901 ty::ReEarlyBound(_re) => {
902 // FIXME(chalk): jackh726 - I think we should always have already
903 // substituted away `ReEarlyBound`s for `ReLateBound`s, but need to confirm.
910 r.super_visit_with(self)
914 /// This is used to replace `BoundRegionKind::BrNamed` with `BoundRegionKind::BrAnon`.
915 /// Note: we assume that we will always have room for more bound vars. (i.e. we
916 /// won't ever hit the `u32` limit in `BrAnon`s).
917 struct NamedBoundVarSubstitutor<'a, 'tcx> {
919 binder_index: ty::DebruijnIndex,
920 named_parameters: &'a BTreeMap<DefId, u32>,
923 impl<'a, 'tcx> NamedBoundVarSubstitutor<'a, 'tcx> {
924 fn new(tcx: TyCtxt<'tcx>, named_parameters: &'a BTreeMap<DefId, u32>) -> Self {
925 NamedBoundVarSubstitutor { tcx, binder_index: ty::INNERMOST, named_parameters }
929 impl<'a, 'tcx> TypeFolder<'tcx> for NamedBoundVarSubstitutor<'a, 'tcx> {
930 fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
934 fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: Binder<T>) -> Binder<T> {
935 self.binder_index.shift_in(1);
936 let result = t.super_fold_with(self);
937 self.binder_index.shift_out(1);
941 fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
943 ty::ReLateBound(index, br) if *index == self.binder_index => match br.kind {
944 ty::BrNamed(def_id, _name) => match self.named_parameters.get(&def_id) {
946 let new_br = ty::BoundRegion { kind: ty::BrAnon(*idx) };
947 return self.tcx.mk_region(RegionKind::ReLateBound(*index, new_br));
949 None => panic!("Missing `BrNamed`."),
951 ty::BrEnv => unimplemented!(),
957 r.super_fold_with(self)
961 /// Used to substitute `Param`s with placeholders. We do this since Chalk
962 /// have a notion of `Param`s.
963 crate struct ParamsSubstitutor<'tcx> {
965 binder_index: ty::DebruijnIndex,
966 list: Vec<rustc_middle::ty::ParamTy>,
967 next_ty_placeholder: usize,
968 crate params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
969 crate named_regions: BTreeMap<DefId, u32>,
972 impl<'tcx> ParamsSubstitutor<'tcx> {
973 crate fn new(tcx: TyCtxt<'tcx>, next_ty_placeholder: usize) -> Self {
976 binder_index: ty::INNERMOST,
979 params: rustc_data_structures::fx::FxHashMap::default(),
980 named_regions: BTreeMap::default(),
985 impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
986 fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
990 fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: Binder<T>) -> Binder<T> {
991 self.binder_index.shift_in(1);
992 let result = t.super_fold_with(self);
993 self.binder_index.shift_out(1);
997 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
999 // FIXME(chalk): currently we convert params to placeholders starting at
1000 // index `0`. To support placeholders, we'll actually need to do a
1001 // first pass to collect placeholders. Then we can insert params after.
1002 ty::Placeholder(_) => unimplemented!(),
1003 ty::Param(param) => match self.list.iter().position(|r| r == ¶m) {
1004 Some(idx) => self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
1005 universe: ty::UniverseIndex::from_usize(0),
1006 name: ty::BoundVar::from_usize(idx),
1009 self.list.push(param);
1010 let idx = self.list.len() - 1 + self.next_ty_placeholder;
1011 self.params.insert(idx, param);
1012 self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
1013 universe: ty::UniverseIndex::from_usize(0),
1014 name: ty::BoundVar::from_usize(idx),
1019 _ => t.super_fold_with(self),
1023 fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
1025 // FIXME(chalk) - jackh726 - this currently isn't hit in any tests.
1026 // This covers any region variables in a goal, right?
1027 ty::ReEarlyBound(_re) => match self.named_regions.get(&_re.def_id) {
1029 let br = ty::BoundRegion { kind: ty::BrAnon(*idx) };
1030 self.tcx.mk_region(RegionKind::ReLateBound(self.binder_index, br))
1033 let idx = self.named_regions.len() as u32;
1034 let br = ty::BoundRegion { kind: ty::BrAnon(idx) };
1035 self.named_regions.insert(_re.def_id, idx);
1036 self.tcx.mk_region(RegionKind::ReLateBound(self.binder_index, br))
1040 _ => r.super_fold_with(self),
1045 /// Used to collect `Placeholder`s.
1046 crate struct PlaceholdersCollector {
1047 universe_index: ty::UniverseIndex,
1048 crate next_ty_placeholder: usize,
1049 crate next_anon_region_placeholder: u32,
1052 impl PlaceholdersCollector {
1053 crate fn new() -> Self {
1054 PlaceholdersCollector {
1055 universe_index: ty::UniverseIndex::ROOT,
1056 next_ty_placeholder: 0,
1057 next_anon_region_placeholder: 0,
1062 impl<'tcx> TypeVisitor<'tcx> for PlaceholdersCollector {
1063 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1065 ty::Placeholder(p) if p.universe == self.universe_index => {
1066 self.next_ty_placeholder = self.next_ty_placeholder.max(p.name.as_usize() + 1);
1072 t.super_visit_with(self)
1075 fn visit_region(&mut self, r: Region<'tcx>) -> ControlFlow<Self::BreakTy> {
1077 ty::RePlaceholder(p) if p.universe == self.universe_index => {
1078 if let ty::BoundRegionKind::BrAnon(anon) = p.name {
1079 self.next_anon_region_placeholder = self.next_anon_region_placeholder.max(anon);
1086 r.super_visit_with(self)
1090 /// Used to substitute specific `Regions`s with placeholders.
1091 crate struct RegionsSubstitutor<'tcx> {
1093 reempty_placeholder: ty::Region<'tcx>,
1096 impl<'tcx> RegionsSubstitutor<'tcx> {
1097 crate fn new(tcx: TyCtxt<'tcx>, reempty_placeholder: ty::Region<'tcx>) -> Self {
1098 RegionsSubstitutor { tcx, reempty_placeholder }
1102 impl<'tcx> TypeFolder<'tcx> for RegionsSubstitutor<'tcx> {
1103 fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
1107 fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
1109 ty::ReEmpty(ui) => {
1110 assert_eq!(ui.as_usize(), 0);
1111 self.reempty_placeholder
1114 _ => r.super_fold_with(self),