src/librustc_traits/chalk/db.rs

   1 //! Provides the `RustIrDatabase` implementation for `chalk-solve`
   2 //!
   3 //! The purpose of the `chalk_solve::RustIrDatabase` is to get data about
   4 //! specific types, such as bounds, where clauses, or fields. This file contains
   5 //! the minimal logic to assemble the types for `chalk-solve` by calling out to
   6 //! either the `TyCtxt` (for information about types) or
   7 //! `crate::chalk::lowering` (to lower rustc types into Chalk types).
   8
   9 use rustc_middle::traits::ChalkRustInterner as RustInterner;
  10 use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
  11 use rustc_middle::ty::{self, AssocItemContainer, AssocKind, TyCtxt};
  12
  13 use rustc_hir::def_id::DefId;
  14
  15 use rustc_span::symbol::sym;
  16
  17 use std::fmt;
  18 use std::sync::Arc;
  19
  20 use crate::chalk::lowering::LowerInto;
  21
  22 pub struct RustIrDatabase<'tcx> {
  23     pub tcx: TyCtxt<'tcx>,
  24     pub interner: RustInterner<'tcx>,
  25 }
  26
  27 impl fmt::Debug for RustIrDatabase<'_> {
  28     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  29         write!(f, "RustIrDatabase")
  30     }
  31 }
  32
  33 impl<'tcx> chalk_solve::RustIrDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
  34     fn interner(&self) -> &RustInterner<'tcx> {
  35         &self.interner
  36     }
  37
  38     fn associated_ty_data(
  39         &self,
  40         assoc_type_id: chalk_ir::AssocTypeId<RustInterner<'tcx>>,
  41     ) -> Arc<chalk_solve::rust_ir::AssociatedTyDatum<RustInterner<'tcx>>> {
  42         let def_id = assoc_type_id.0;
  43         let assoc_item = self.tcx.associated_item(def_id);
  44         let trait_def_id = match assoc_item.container {
  45             AssocItemContainer::TraitContainer(def_id) => def_id,
  46             _ => unimplemented!("Not possible??"),
  47         };
  48         match assoc_item.kind {
  49             AssocKind::Type => {}
  50             _ => unimplemented!("Not possible??"),
  51         }
  52         let bound_vars = bound_vars_for_item(self.tcx, def_id);
  53         let binders = binders_for(&self.interner, bound_vars);
  54         // FIXME(chalk): this really isn't right I don't think. The functions
  55         // for GATs are a bit hard to figure out. Are these supposed to be where
  56         // clauses or bounds?
  57         let predicates = self.tcx.predicates_defined_on(def_id).predicates;
  58         let where_clauses: Vec<_> = predicates
  59             .iter()
  60             .map(|(wc, _)| wc.subst(self.tcx, &bound_vars))
  61             .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
  62
  63         Arc::new(chalk_solve::rust_ir::AssociatedTyDatum {
  64             trait_id: chalk_ir::TraitId(trait_def_id),
  65             id: assoc_type_id,
  66             name: (),
  67             binders: chalk_ir::Binders::new(
  68                 binders,
  69                 chalk_solve::rust_ir::AssociatedTyDatumBound { bounds: vec![], where_clauses },
  70             ),
  71         })
  72     }
  73
  74     fn trait_datum(
  75         &self,
  76         trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
  77     ) -> Arc<chalk_solve::rust_ir::TraitDatum<RustInterner<'tcx>>> {
  78         let def_id = trait_id.0;
  79         let trait_def = self.tcx.trait_def(def_id);
  80
  81         let bound_vars = bound_vars_for_item(self.tcx, def_id);
  82         let binders = binders_for(&self.interner, bound_vars);
  83         let predicates = self.tcx.predicates_defined_on(def_id).predicates;
  84         let where_clauses: Vec<_> = predicates
  85             .iter()
  86             .map(|(wc, _)| wc.subst(self.tcx, &bound_vars))
  87             .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
  88         let associated_ty_ids: Vec<_> = self
  89             .tcx
  90             .associated_items(def_id)
  91             .in_definition_order()
  92             .filter(|i| i.kind == AssocKind::Type)
  93             .map(|i| chalk_ir::AssocTypeId(i.def_id))
  94             .collect();
  95
  96         let well_known =
  97             if self.tcx.lang_items().sized_trait().map(|t| def_id == t).unwrap_or(false) {
  98                 Some(chalk_solve::rust_ir::WellKnownTrait::Sized)
  99             } else if self.tcx.lang_items().copy_trait().map(|t| def_id == t).unwrap_or(false) {
 100                 Some(chalk_solve::rust_ir::WellKnownTrait::Copy)
 101             } else if self.tcx.lang_items().clone_trait().map(|t| def_id == t).unwrap_or(false) {
 102                 Some(chalk_solve::rust_ir::WellKnownTrait::Clone)
 103             } else if self.tcx.lang_items().drop_trait().map(|t| def_id == t).unwrap_or(false) {
 104                 Some(chalk_solve::rust_ir::WellKnownTrait::Drop)
 105             } else if self.tcx.lang_items().fn_trait().map(|t| def_id == t).unwrap_or(false) {
 106                 Some(chalk_solve::rust_ir::WellKnownTrait::Fn)
 107             } else if self.tcx.lang_items().fn_once_trait().map(|t| def_id == t).unwrap_or(false) {
 108                 Some(chalk_solve::rust_ir::WellKnownTrait::FnOnce)
 109             } else if self.tcx.lang_items().fn_mut_trait().map(|t| def_id == t).unwrap_or(false) {
 110                 Some(chalk_solve::rust_ir::WellKnownTrait::FnMut)
 111             } else {
 112                 None
 113             };
 114         Arc::new(chalk_solve::rust_ir::TraitDatum {
 115             id: trait_id,
 116             binders: chalk_ir::Binders::new(
 117                 binders,
 118                 chalk_solve::rust_ir::TraitDatumBound { where_clauses },
 119             ),
 120             flags: chalk_solve::rust_ir::TraitFlags {
 121                 auto: trait_def.has_auto_impl,
 122                 marker: trait_def.is_marker,
 123                 upstream: !def_id.is_local(),
 124                 fundamental: self.tcx.has_attr(def_id, sym::fundamental),
 125                 non_enumerable: true,
 126                 coinductive: false,
 127             },
 128             associated_ty_ids,
 129             well_known,
 130         })
 131     }
 132
 133     fn adt_datum(
 134         &self,
 135         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 136     ) -> Arc<chalk_solve::rust_ir::AdtDatum<RustInterner<'tcx>>> {
 137         let adt_def = adt_id.0;
 138
 139         let bound_vars = bound_vars_for_item(self.tcx, adt_def.did);
 140         let binders = binders_for(&self.interner, bound_vars);
 141
 142         let predicates = self.tcx.predicates_of(adt_def.did).predicates;
 143         let where_clauses: Vec<_> = predicates
 144             .iter()
 145             .map(|(wc, _)| wc.subst(self.tcx, bound_vars))
 146             .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner))
 147             .collect();
 148         let fields = match adt_def.adt_kind() {
 149             ty::AdtKind::Struct | ty::AdtKind::Union => {
 150                 let variant = adt_def.non_enum_variant();
 151                 variant
 152                     .fields
 153                     .iter()
 154                     .map(|field| {
 155                         self.tcx
 156                             .type_of(field.did)
 157                             .subst(self.tcx, bound_vars)
 158                             .lower_into(&self.interner)
 159                     })
 160                     .collect()
 161             }
 162             // FIXME(chalk): handle enums; force_impl_for requires this
 163             ty::AdtKind::Enum => vec![],
 164         };
 165         let struct_datum = Arc::new(chalk_solve::rust_ir::AdtDatum {
 166             id: adt_id,
 167             binders: chalk_ir::Binders::new(
 168                 binders,
 169                 chalk_solve::rust_ir::AdtDatumBound { fields, where_clauses },
 170             ),
 171             flags: chalk_solve::rust_ir::AdtFlags {
 172                 upstream: !adt_def.did.is_local(),
 173                 fundamental: adt_def.is_fundamental(),
 174                 phantom_data: adt_def.is_phantom_data(),
 175             },
 176         });
 177         struct_datum
 178     }
 179
 180     fn fn_def_datum(
 181         &self,
 182         fn_def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
 183     ) -> Arc<chalk_solve::rust_ir::FnDefDatum<RustInterner<'tcx>>> {
 184         let def_id = fn_def_id.0;
 185         let bound_vars = bound_vars_for_item(self.tcx, def_id);
 186         let binders = binders_for(&self.interner, bound_vars);
 187
 188         let predicates = self.tcx.predicates_defined_on(def_id).predicates;
 189         let where_clauses: Vec<_> = predicates
 190             .iter()
 191             .map(|(wc, _)| wc.subst(self.tcx, &bound_vars))
 192             .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
 193
 194         let sig = self.tcx.fn_sig(def_id);
 195         let inputs_and_output = sig.inputs_and_output();
 196         let (inputs_and_output, iobinders, _) = crate::chalk::lowering::collect_bound_vars(
 197             &self.interner,
 198             self.tcx,
 199             &inputs_and_output,
 200         );
 201
 202         let argument_types = inputs_and_output[..inputs_and_output.len() - 1]
 203             .iter()
 204             .map(|t| t.subst(self.tcx, &bound_vars).lower_into(&self.interner))
 205             .collect();
 206
 207         let return_type = inputs_and_output[inputs_and_output.len() - 1]
 208             .subst(self.tcx, &bound_vars)
 209             .lower_into(&self.interner);
 210
 211         let bound = chalk_solve::rust_ir::FnDefDatumBound {
 212             inputs_and_output: chalk_ir::Binders::new(
 213                 iobinders,
 214                 chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
 215             ),
 216             where_clauses,
 217         };
 218         Arc::new(chalk_solve::rust_ir::FnDefDatum {
 219             id: fn_def_id,
 220             abi: sig.abi(),
 221             binders: chalk_ir::Binders::new(binders, bound),
 222         })
 223     }
 224
 225     fn impl_datum(
 226         &self,
 227         impl_id: chalk_ir::ImplId<RustInterner<'tcx>>,
 228     ) -> Arc<chalk_solve::rust_ir::ImplDatum<RustInterner<'tcx>>> {
 229         let def_id = impl_id.0;
 230         let bound_vars = bound_vars_for_item(self.tcx, def_id);
 231         let binders = binders_for(&self.interner, bound_vars);
 232
 233         let trait_ref = self.tcx.impl_trait_ref(def_id).expect("not an impl");
 234         let trait_ref = trait_ref.subst(self.tcx, bound_vars);
 235
 236         let predicates = self.tcx.predicates_of(def_id).predicates;
 237         let where_clauses: Vec<_> = predicates
 238             .iter()
 239             .map(|(wc, _)| wc.subst(self.tcx, bound_vars))
 240             .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
 241
 242         let value = chalk_solve::rust_ir::ImplDatumBound {
 243             trait_ref: trait_ref.lower_into(&self.interner),
 244             where_clauses,
 245         };
 246
 247         Arc::new(chalk_solve::rust_ir::ImplDatum {
 248             polarity: chalk_solve::rust_ir::Polarity::Positive,
 249             binders: chalk_ir::Binders::new(binders, value),
 250             impl_type: chalk_solve::rust_ir::ImplType::Local,
 251             associated_ty_value_ids: vec![],
 252         })
 253     }
 254
 255     fn impls_for_trait(
 256         &self,
 257         trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 258         parameters: &[chalk_ir::GenericArg<RustInterner<'tcx>>],
 259     ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
 260         let def_id = trait_id.0;
 261
 262         // FIXME(chalk): use TraitDef::for_each_relevant_impl, but that will
 263         // require us to be able to interconvert `Ty<'tcx>`, and we're
 264         // not there yet.
 265
 266         let all_impls = self.tcx.all_impls(def_id);
 267         let matched_impls = all_impls.filter(|impl_def_id| {
 268             use chalk_ir::could_match::CouldMatch;
 269             let trait_ref = self.tcx.impl_trait_ref(*impl_def_id).unwrap();
 270             let bound_vars = bound_vars_for_item(self.tcx, *impl_def_id);
 271
 272             let self_ty = trait_ref.self_ty();
 273             let self_ty = self_ty.subst(self.tcx, bound_vars);
 274             let lowered_ty = self_ty.lower_into(&self.interner);
 275
 276             parameters[0].assert_ty_ref(&self.interner).could_match(&self.interner, &lowered_ty)
 277         });
 278
 279         let impls = matched_impls.map(chalk_ir::ImplId).collect();
 280         impls
 281     }
 282
 283     fn impl_provided_for(
 284         &self,
 285         auto_trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 286         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 287     ) -> bool {
 288         let trait_def_id = auto_trait_id.0;
 289         let adt_def = adt_id.0;
 290         let all_impls = self.tcx.all_impls(trait_def_id);
 291         for impl_def_id in all_impls {
 292             let trait_ref = self.tcx.impl_trait_ref(impl_def_id).unwrap();
 293             let self_ty = trait_ref.self_ty();
 294             match self_ty.kind {
 295                 ty::Adt(impl_adt_def, _) => {
 296                     if impl_adt_def == adt_def {
 297                         return true;
 298                     }
 299                 }
 300                 _ => {}
 301             }
 302         }
 303         false
 304     }
 305
 306     fn associated_ty_value(
 307         &self,
 308         associated_ty_id: chalk_solve::rust_ir::AssociatedTyValueId<RustInterner<'tcx>>,
 309     ) -> Arc<chalk_solve::rust_ir::AssociatedTyValue<RustInterner<'tcx>>> {
 310         let def_id = associated_ty_id.0;
 311         let assoc_item = self.tcx.associated_item(def_id);
 312         let impl_id = match assoc_item.container {
 313             AssocItemContainer::TraitContainer(def_id) => def_id,
 314             _ => unimplemented!("Not possible??"),
 315         };
 316         match assoc_item.kind {
 317             AssocKind::Type => {}
 318             _ => unimplemented!("Not possible??"),
 319         }
 320         let bound_vars = bound_vars_for_item(self.tcx, def_id);
 321         let binders = binders_for(&self.interner, bound_vars);
 322         let ty = self.tcx.type_of(def_id);
 323
 324         Arc::new(chalk_solve::rust_ir::AssociatedTyValue {
 325             impl_id: chalk_ir::ImplId(impl_id),
 326             associated_ty_id: chalk_ir::AssocTypeId(def_id),
 327             value: chalk_ir::Binders::new(
 328                 binders,
 329                 chalk_solve::rust_ir::AssociatedTyValueBound { ty: ty.lower_into(&self.interner) },
 330             ),
 331         })
 332     }
 333
 334     fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<RustInterner<'tcx>>> {
 335         vec![]
 336     }
 337
 338     fn local_impls_to_coherence_check(
 339         &self,
 340         _trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 341     ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
 342         unimplemented!()
 343     }
 344
 345     fn opaque_ty_data(
 346         &self,
 347         opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 348     ) -> Arc<chalk_solve::rust_ir::OpaqueTyDatum<RustInterner<'tcx>>> {
 349         let bound_vars = bound_vars_for_item(self.tcx, opaque_ty_id.0);
 350         let binders = binders_for(&self.interner, bound_vars);
 351         let predicates = self.tcx.predicates_defined_on(opaque_ty_id.0).predicates;
 352         let where_clauses: Vec<_> = predicates
 353             .iter()
 354             .map(|(wc, _)| wc.subst(self.tcx, &bound_vars))
 355             .filter_map(|wc| LowerInto::<Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>>::lower_into(wc, &self.interner)).collect();
 356
 357         let value = chalk_solve::rust_ir::OpaqueTyDatumBound {
 358             bounds: chalk_ir::Binders::new(binders, where_clauses),
 359         };
 360         Arc::new(chalk_solve::rust_ir::OpaqueTyDatum {
 361             opaque_ty_id,
 362             bound: chalk_ir::Binders::new(chalk_ir::VariableKinds::new(&self.interner), value),
 363         })
 364     }
 365
 366     /// Since Chalk can't handle all Rust types currently, we have to handle
 367     /// some specially for now. Over time, these `Some` returns will change to
 368     /// `None` and eventually this function will be removed.
 369     fn force_impl_for(
 370         &self,
 371         well_known: chalk_solve::rust_ir::WellKnownTrait,
 372         ty: &chalk_ir::TyData<RustInterner<'tcx>>,
 373     ) -> Option<bool> {
 374         use chalk_ir::TyData::*;
 375         match well_known {
 376             chalk_solve::rust_ir::WellKnownTrait::Sized => match ty {
 377                 Apply(apply) => match apply.name {
 378                     chalk_ir::TypeName::Adt(chalk_ir::AdtId(adt_def)) => match adt_def.adt_kind() {
 379                         ty::AdtKind::Struct | ty::AdtKind::Union => None,
 380                         ty::AdtKind::Enum => {
 381                             let constraint = self.tcx.adt_sized_constraint(adt_def.did);
 382                             if !constraint.0.is_empty() { unimplemented!() } else { Some(true) }
 383                         }
 384                     },
 385                     _ => None,
 386                 },
 387                 Dyn(_)
 388                 | Alias(_)
 389                 | Placeholder(_)
 390                 | Function(_)
 391                 | InferenceVar(_, _)
 392                 | BoundVar(_) => None,
 393             },
 394             chalk_solve::rust_ir::WellKnownTrait::Copy
 395             | chalk_solve::rust_ir::WellKnownTrait::Clone => match ty {
 396                 Apply(apply) => match apply.name {
 397                     chalk_ir::TypeName::Adt(chalk_ir::AdtId(adt_def)) => match adt_def.adt_kind() {
 398                         ty::AdtKind::Struct | ty::AdtKind::Union => None,
 399                         ty::AdtKind::Enum => {
 400                             let constraint = self.tcx.adt_sized_constraint(adt_def.did);
 401                             if !constraint.0.is_empty() { unimplemented!() } else { Some(true) }
 402                         }
 403                     },
 404                     _ => None,
 405                 },
 406                 Dyn(_)
 407                 | Alias(_)
 408                 | Placeholder(_)
 409                 | Function(_)
 410                 | InferenceVar(_, _)
 411                 | BoundVar(_) => None,
 412             },
 413             chalk_solve::rust_ir::WellKnownTrait::Drop => None,
 414             chalk_solve::rust_ir::WellKnownTrait::Fn => None,
 415             chalk_solve::rust_ir::WellKnownTrait::FnMut => None,
 416             chalk_solve::rust_ir::WellKnownTrait::FnOnce => None,
 417             chalk_solve::rust_ir::WellKnownTrait::Unsize => None,
 418         }
 419     }
 420
 421     fn program_clauses_for_env(
 422         &self,
 423         environment: &chalk_ir::Environment<RustInterner<'tcx>>,
 424     ) -> chalk_ir::ProgramClauses<RustInterner<'tcx>> {
 425         chalk_solve::program_clauses_for_env(self, environment)
 426     }
 427
 428     fn well_known_trait_id(
 429         &self,
 430         well_known_trait: chalk_solve::rust_ir::WellKnownTrait,
 431     ) -> Option<chalk_ir::TraitId<RustInterner<'tcx>>> {
 432         use chalk_solve::rust_ir::WellKnownTrait::*;
 433         let def_id = match well_known_trait {
 434             Sized => self.tcx.lang_items().sized_trait(),
 435             Copy => self.tcx.lang_items().copy_trait(),
 436             Clone => self.tcx.lang_items().clone_trait(),
 437             Drop => self.tcx.lang_items().drop_trait(),
 438             Fn => self.tcx.lang_items().fn_trait(),
 439             FnMut => self.tcx.lang_items().fn_mut_trait(),
 440             FnOnce => self.tcx.lang_items().fn_once_trait(),
 441             Unsize => self.tcx.lang_items().unsize_trait(),
 442         };
 443         def_id.map(chalk_ir::TraitId)
 444     }
 445
 446     fn is_object_safe(&self, trait_id: chalk_ir::TraitId<RustInterner<'tcx>>) -> bool {
 447         self.tcx.is_object_safe(trait_id.0)
 448     }
 449
 450     fn hidden_opaque_type(
 451         &self,
 452         _id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 453     ) -> chalk_ir::Ty<RustInterner<'tcx>> {
 454         // FIXME(chalk): actually get hidden ty
 455         self.tcx.mk_ty(ty::Tuple(self.tcx.intern_substs(&[]))).lower_into(&self.interner)
 456     }
 457
 458     fn closure_kind(
 459         &self,
 460         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 461         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 462     ) -> chalk_solve::rust_ir::ClosureKind {
 463         let kind = &substs.parameters(&self.interner)[substs.len(&self.interner) - 3];
 464         match kind.assert_ty_ref(&self.interner).data(&self.interner) {
 465             chalk_ir::TyData::Apply(apply) => match apply.name {
 466                 chalk_ir::TypeName::Scalar(scalar) => match scalar {
 467                     chalk_ir::Scalar::Int(int_ty) => match int_ty {
 468                         chalk_ir::IntTy::I8 => chalk_solve::rust_ir::ClosureKind::Fn,
 469                         chalk_ir::IntTy::I16 => chalk_solve::rust_ir::ClosureKind::FnMut,
 470                         chalk_ir::IntTy::I32 => chalk_solve::rust_ir::ClosureKind::FnOnce,
 471                         _ => bug!("bad closure kind"),
 472                     },
 473                     _ => bug!("bad closure kind"),
 474                 },
 475                 _ => bug!("bad closure kind"),
 476             },
 477             _ => bug!("bad closure kind"),
 478         }
 479     }
 480
 481     fn closure_inputs_and_output(
 482         &self,
 483         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 484         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 485     ) -> chalk_ir::Binders<chalk_solve::rust_ir::FnDefInputsAndOutputDatum<RustInterner<'tcx>>>
 486     {
 487         let sig = &substs.parameters(&self.interner)[substs.len(&self.interner) - 2];
 488         match sig.assert_ty_ref(&self.interner).data(&self.interner) {
 489             chalk_ir::TyData::Function(f) => {
 490                 let substitution = f.substitution.parameters(&self.interner);
 491                 let return_type =
 492                     substitution.last().unwrap().assert_ty_ref(&self.interner).clone();
 493                 // Closure arguments are tupled
 494                 let argument_tuple = substitution[0].assert_ty_ref(&self.interner);
 495                 let argument_types = match argument_tuple.data(&self.interner) {
 496                     chalk_ir::TyData::Apply(apply) => match apply.name {
 497                         chalk_ir::TypeName::Tuple(_) => apply
 498                             .substitution
 499                             .iter(&self.interner)
 500                             .map(|arg| arg.assert_ty_ref(&self.interner))
 501                             .cloned()
 502                             .collect(),
 503                         _ => bug!("Expecting closure FnSig args to be tupled."),
 504                     },
 505                     _ => bug!("Expecting closure FnSig args to be tupled."),
 506                 };
 507
 508                 chalk_ir::Binders::new(
 509                     chalk_ir::VariableKinds::from(
 510                         &self.interner,
 511                         (0..f.num_binders).map(|_| chalk_ir::VariableKind::Lifetime),
 512                     ),
 513                     chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
 514                 )
 515             }
 516             _ => panic!("Invalid sig."),
 517         }
 518     }
 519
 520     fn closure_upvars(
 521         &self,
 522         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 523         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 524     ) -> chalk_ir::Binders<chalk_ir::Ty<RustInterner<'tcx>>> {
 525         let inputs_and_output = self.closure_inputs_and_output(_closure_id, substs);
 526         let tuple = substs.parameters(&self.interner).last().unwrap().assert_ty_ref(&self.interner);
 527         inputs_and_output.map_ref(|_| tuple.clone())
 528     }
 529
 530     fn closure_fn_substitution(
 531         &self,
 532         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 533         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 534     ) -> chalk_ir::Substitution<RustInterner<'tcx>> {
 535         let substitution = &substs.parameters(&self.interner)[0..substs.len(&self.interner) - 3];
 536         chalk_ir::Substitution::from(&self.interner, substitution)
 537     }
 538 }
 539
 540 /// Creates a `InternalSubsts` that maps each generic parameter to a higher-ranked
 541 /// var bound at index `0`. For types, we use a `BoundVar` index equal to
 542 /// the type parameter index. For regions, we use the `BoundRegion::BrNamed`
 543 /// variant (which has a `DefId`).
 544 fn bound_vars_for_item(tcx: TyCtxt<'tcx>, def_id: DefId) -> SubstsRef<'tcx> {
 545     InternalSubsts::for_item(tcx, def_id, |param, substs| match param.kind {
 546         ty::GenericParamDefKind::Type { .. } => tcx
 547             .mk_ty(ty::Bound(
 548                 ty::INNERMOST,
 549                 ty::BoundTy {
 550                     var: ty::BoundVar::from(param.index),
 551                     kind: ty::BoundTyKind::Param(param.name),
 552                 },
 553             ))
 554             .into(),
 555
 556         ty::GenericParamDefKind::Lifetime => tcx
 557             .mk_region(ty::RegionKind::ReLateBound(
 558                 ty::INNERMOST,
 559                 ty::BoundRegion::BrAnon(substs.len() as u32),
 560             ))
 561             .into(),
 562
 563         ty::GenericParamDefKind::Const => tcx
 564             .mk_const(ty::Const {
 565                 val: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
 566                 ty: tcx.type_of(param.def_id),
 567             })
 568             .into(),
 569     })
 570 }
 571
 572 fn binders_for<'tcx>(
 573     interner: &RustInterner<'tcx>,
 574     bound_vars: SubstsRef<'tcx>,
 575 ) -> chalk_ir::VariableKinds<RustInterner<'tcx>> {
 576     chalk_ir::VariableKinds::from(
 577         interner,
 578         bound_vars.iter().map(|arg| match arg.unpack() {
 579             ty::subst::GenericArgKind::Lifetime(_re) => chalk_ir::VariableKind::Lifetime,
 580             ty::subst::GenericArgKind::Type(_ty) => {
 581                 chalk_ir::VariableKind::Ty(chalk_ir::TyKind::General)
 582             }
 583             ty::subst::GenericArgKind::Const(c) => {
 584                 chalk_ir::VariableKind::Const(c.ty.lower_into(interner))
 585             }
 586         }),
 587     )
 588 }