compiler/rustc_traits/src/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, Ty, TyCtxt, TypeFoldable};
  12
  13 use rustc_ast::ast;
  14 use rustc_attr as attr;
  15
  16 use rustc_hir::def_id::DefId;
  17
  18 use rustc_span::symbol::sym;
  19
  20 use std::fmt;
  21 use std::sync::Arc;
  22
  23 use crate::chalk::lowering::LowerInto;
  24
  25 pub struct RustIrDatabase<'tcx> {
  26     pub(crate) interner: RustInterner<'tcx>,
  27 }
  28
  29 impl fmt::Debug for RustIrDatabase<'_> {
  30     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  31         write!(f, "RustIrDatabase")
  32     }
  33 }
  34
  35 impl<'tcx> RustIrDatabase<'tcx> {
  36     fn where_clauses_for(
  37         &self,
  38         def_id: DefId,
  39         bound_vars: SubstsRef<'tcx>,
  40     ) -> Vec<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> {
  41         let predicates = self.interner.tcx.predicates_defined_on(def_id).predicates;
  42         predicates
  43             .iter()
  44             .map(|(wc, _)| wc.subst(self.interner.tcx, bound_vars))
  45             .filter_map(|wc| LowerInto::<
  46                     Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>
  47                     >::lower_into(wc, self.interner)).collect()
  48     }
  49
  50     fn bounds_for<T>(&self, def_id: DefId, bound_vars: SubstsRef<'tcx>) -> Vec<T>
  51     where
  52         ty::Predicate<'tcx>: LowerInto<'tcx, std::option::Option<T>>,
  53     {
  54         self.interner
  55             .tcx
  56             .explicit_item_bounds(def_id)
  57             .iter()
  58             .map(|(bound, _)| bound.subst(self.interner.tcx, &bound_vars))
  59             .filter_map(|bound| LowerInto::<Option<_>>::lower_into(bound, self.interner))
  60             .collect()
  61     }
  62 }
  63
  64 impl<'tcx> chalk_solve::RustIrDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
  65     fn interner(&self) -> RustInterner<'tcx> {
  66         self.interner
  67     }
  68
  69     fn associated_ty_data(
  70         &self,
  71         assoc_type_id: chalk_ir::AssocTypeId<RustInterner<'tcx>>,
  72     ) -> Arc<chalk_solve::rust_ir::AssociatedTyDatum<RustInterner<'tcx>>> {
  73         let def_id = assoc_type_id.0;
  74         let assoc_item = self.interner.tcx.associated_item(def_id);
  75         let AssocItemContainer::TraitContainer(trait_def_id) = assoc_item.container else {
  76             unimplemented!("Not possible??");
  77         };
  78         match assoc_item.kind {
  79             AssocKind::Type => {}
  80             _ => unimplemented!("Not possible??"),
  81         }
  82         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
  83         let binders = binders_for(self.interner, bound_vars);
  84
  85         let where_clauses = self.where_clauses_for(def_id, bound_vars);
  86         let bounds = self.bounds_for(def_id, bound_vars);
  87
  88         Arc::new(chalk_solve::rust_ir::AssociatedTyDatum {
  89             trait_id: chalk_ir::TraitId(trait_def_id),
  90             id: assoc_type_id,
  91             name: (),
  92             binders: chalk_ir::Binders::new(
  93                 binders,
  94                 chalk_solve::rust_ir::AssociatedTyDatumBound { bounds, where_clauses },
  95             ),
  96         })
  97     }
  98
  99     fn trait_datum(
 100         &self,
 101         trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 102     ) -> Arc<chalk_solve::rust_ir::TraitDatum<RustInterner<'tcx>>> {
 103         let def_id = trait_id.0;
 104         let trait_def = self.interner.tcx.trait_def(def_id);
 105
 106         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 107         let binders = binders_for(self.interner, bound_vars);
 108
 109         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 110
 111         let associated_ty_ids: Vec<_> = self
 112             .interner
 113             .tcx
 114             .associated_items(def_id)
 115             .in_definition_order()
 116             .filter(|i| i.kind == AssocKind::Type)
 117             .map(|i| chalk_ir::AssocTypeId(i.def_id))
 118             .collect();
 119
 120         let lang_items = self.interner.tcx.lang_items();
 121         let well_known = if lang_items.sized_trait() == Some(def_id) {
 122             Some(chalk_solve::rust_ir::WellKnownTrait::Sized)
 123         } else if lang_items.copy_trait() == Some(def_id) {
 124             Some(chalk_solve::rust_ir::WellKnownTrait::Copy)
 125         } else if lang_items.clone_trait() == Some(def_id) {
 126             Some(chalk_solve::rust_ir::WellKnownTrait::Clone)
 127         } else if lang_items.drop_trait() == Some(def_id) {
 128             Some(chalk_solve::rust_ir::WellKnownTrait::Drop)
 129         } else if lang_items.fn_trait() == Some(def_id) {
 130             Some(chalk_solve::rust_ir::WellKnownTrait::Fn)
 131         } else if lang_items.fn_once_trait() == Some(def_id) {
 132             Some(chalk_solve::rust_ir::WellKnownTrait::FnOnce)
 133         } else if lang_items.fn_mut_trait() == Some(def_id) {
 134             Some(chalk_solve::rust_ir::WellKnownTrait::FnMut)
 135         } else if lang_items.unsize_trait() == Some(def_id) {
 136             Some(chalk_solve::rust_ir::WellKnownTrait::Unsize)
 137         } else if lang_items.unpin_trait() == Some(def_id) {
 138             Some(chalk_solve::rust_ir::WellKnownTrait::Unpin)
 139         } else if lang_items.coerce_unsized_trait() == Some(def_id) {
 140             Some(chalk_solve::rust_ir::WellKnownTrait::CoerceUnsized)
 141         } else {
 142             None
 143         };
 144         Arc::new(chalk_solve::rust_ir::TraitDatum {
 145             id: trait_id,
 146             binders: chalk_ir::Binders::new(
 147                 binders,
 148                 chalk_solve::rust_ir::TraitDatumBound { where_clauses },
 149             ),
 150             flags: chalk_solve::rust_ir::TraitFlags {
 151                 auto: trait_def.has_auto_impl,
 152                 marker: trait_def.is_marker,
 153                 upstream: !def_id.is_local(),
 154                 fundamental: self.interner.tcx.has_attr(def_id, sym::fundamental),
 155                 non_enumerable: true,
 156                 coinductive: false,
 157             },
 158             associated_ty_ids,
 159             well_known,
 160         })
 161     }
 162
 163     fn adt_datum(
 164         &self,
 165         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 166     ) -> Arc<chalk_solve::rust_ir::AdtDatum<RustInterner<'tcx>>> {
 167         let adt_def = adt_id.0;
 168
 169         let bound_vars = bound_vars_for_item(self.interner.tcx, adt_def.did);
 170         let binders = binders_for(self.interner, bound_vars);
 171
 172         let where_clauses = self.where_clauses_for(adt_def.did, bound_vars);
 173
 174         let variants: Vec<_> = adt_def
 175             .variants
 176             .iter()
 177             .map(|variant| chalk_solve::rust_ir::AdtVariantDatum {
 178                 fields: variant
 179                     .fields
 180                     .iter()
 181                     .map(|field| field.ty(self.interner.tcx, bound_vars).lower_into(self.interner))
 182                     .collect(),
 183             })
 184             .collect();
 185         Arc::new(chalk_solve::rust_ir::AdtDatum {
 186             id: adt_id,
 187             binders: chalk_ir::Binders::new(
 188                 binders,
 189                 chalk_solve::rust_ir::AdtDatumBound { variants, where_clauses },
 190             ),
 191             flags: chalk_solve::rust_ir::AdtFlags {
 192                 upstream: !adt_def.did.is_local(),
 193                 fundamental: adt_def.is_fundamental(),
 194                 phantom_data: adt_def.is_phantom_data(),
 195             },
 196             kind: match adt_def.adt_kind() {
 197                 ty::AdtKind::Struct => chalk_solve::rust_ir::AdtKind::Struct,
 198                 ty::AdtKind::Union => chalk_solve::rust_ir::AdtKind::Union,
 199                 ty::AdtKind::Enum => chalk_solve::rust_ir::AdtKind::Enum,
 200             },
 201         })
 202     }
 203
 204     fn adt_repr(
 205         &self,
 206         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 207     ) -> Arc<chalk_solve::rust_ir::AdtRepr<RustInterner<'tcx>>> {
 208         let adt_def = adt_id.0;
 209         let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i)).intern(self.interner);
 210         let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i)).intern(self.interner);
 211         Arc::new(chalk_solve::rust_ir::AdtRepr {
 212             c: adt_def.repr.c(),
 213             packed: adt_def.repr.packed(),
 214             int: adt_def.repr.int.map(|i| match i {
 215                 attr::IntType::SignedInt(ty) => match ty {
 216                     ast::IntTy::Isize => int(chalk_ir::IntTy::Isize),
 217                     ast::IntTy::I8 => int(chalk_ir::IntTy::I8),
 218                     ast::IntTy::I16 => int(chalk_ir::IntTy::I16),
 219                     ast::IntTy::I32 => int(chalk_ir::IntTy::I32),
 220                     ast::IntTy::I64 => int(chalk_ir::IntTy::I64),
 221                     ast::IntTy::I128 => int(chalk_ir::IntTy::I128),
 222                 },
 223                 attr::IntType::UnsignedInt(ty) => match ty {
 224                     ast::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
 225                     ast::UintTy::U8 => uint(chalk_ir::UintTy::U8),
 226                     ast::UintTy::U16 => uint(chalk_ir::UintTy::U16),
 227                     ast::UintTy::U32 => uint(chalk_ir::UintTy::U32),
 228                     ast::UintTy::U64 => uint(chalk_ir::UintTy::U64),
 229                     ast::UintTy::U128 => uint(chalk_ir::UintTy::U128),
 230                 },
 231             }),
 232         })
 233     }
 234
 235     fn fn_def_datum(
 236         &self,
 237         fn_def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
 238     ) -> Arc<chalk_solve::rust_ir::FnDefDatum<RustInterner<'tcx>>> {
 239         let def_id = fn_def_id.0;
 240         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 241         let binders = binders_for(self.interner, bound_vars);
 242
 243         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 244
 245         let sig = self.interner.tcx.fn_sig(def_id);
 246         let (inputs_and_output, iobinders, _) = crate::chalk::lowering::collect_bound_vars(
 247             self.interner,
 248             self.interner.tcx,
 249             sig.inputs_and_output().subst(self.interner.tcx, bound_vars),
 250         );
 251
 252         let argument_types = inputs_and_output[..inputs_and_output.len() - 1]
 253             .iter()
 254             .map(|t| t.subst(self.interner.tcx, &bound_vars).lower_into(self.interner))
 255             .collect();
 256
 257         let return_type = inputs_and_output[inputs_and_output.len() - 1]
 258             .subst(self.interner.tcx, &bound_vars)
 259             .lower_into(self.interner);
 260
 261         let bound = chalk_solve::rust_ir::FnDefDatumBound {
 262             inputs_and_output: chalk_ir::Binders::new(
 263                 iobinders,
 264                 chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
 265             ),
 266             where_clauses,
 267         };
 268         Arc::new(chalk_solve::rust_ir::FnDefDatum {
 269             id: fn_def_id,
 270             sig: sig.lower_into(self.interner),
 271             binders: chalk_ir::Binders::new(binders, bound),
 272         })
 273     }
 274
 275     fn impl_datum(
 276         &self,
 277         impl_id: chalk_ir::ImplId<RustInterner<'tcx>>,
 278     ) -> Arc<chalk_solve::rust_ir::ImplDatum<RustInterner<'tcx>>> {
 279         let def_id = impl_id.0;
 280         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 281         let binders = binders_for(self.interner, bound_vars);
 282
 283         let trait_ref = self.interner.tcx.impl_trait_ref(def_id).expect("not an impl");
 284         let trait_ref = trait_ref.subst(self.interner.tcx, bound_vars);
 285
 286         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 287
 288         let value = chalk_solve::rust_ir::ImplDatumBound {
 289             trait_ref: trait_ref.lower_into(self.interner),
 290             where_clauses,
 291         };
 292
 293         let associated_ty_value_ids: Vec<_> = self
 294             .interner
 295             .tcx
 296             .associated_items(def_id)
 297             .in_definition_order()
 298             .filter(|i| i.kind == AssocKind::Type)
 299             .map(|i| chalk_solve::rust_ir::AssociatedTyValueId(i.def_id))
 300             .collect();
 301
 302         Arc::new(chalk_solve::rust_ir::ImplDatum {
 303             polarity: self.interner.tcx.impl_polarity(def_id).lower_into(self.interner),
 304             binders: chalk_ir::Binders::new(binders, value),
 305             impl_type: chalk_solve::rust_ir::ImplType::Local,
 306             associated_ty_value_ids,
 307         })
 308     }
 309
 310     fn impls_for_trait(
 311         &self,
 312         trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 313         parameters: &[chalk_ir::GenericArg<RustInterner<'tcx>>],
 314         _binders: &chalk_ir::CanonicalVarKinds<RustInterner<'tcx>>,
 315     ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
 316         let def_id = trait_id.0;
 317
 318         // FIXME(chalk): use TraitDef::for_each_relevant_impl, but that will
 319         // require us to be able to interconvert `Ty<'tcx>`, and we're
 320         // not there yet.
 321
 322         let all_impls = self.interner.tcx.all_impls(def_id);
 323         let matched_impls = all_impls.filter(|impl_def_id| {
 324             use chalk_ir::could_match::CouldMatch;
 325             let trait_ref = self.interner.tcx.impl_trait_ref(*impl_def_id).unwrap();
 326             let bound_vars = bound_vars_for_item(self.interner.tcx, *impl_def_id);
 327
 328             let self_ty = trait_ref.self_ty();
 329             let self_ty = self_ty.subst(self.interner.tcx, bound_vars);
 330             let lowered_ty = self_ty.lower_into(self.interner);
 331
 332             parameters[0].assert_ty_ref(self.interner).could_match(
 333                 self.interner,
 334                 self.unification_database(),
 335                 &lowered_ty,
 336             )
 337         });
 338
 339         let impls = matched_impls.map(chalk_ir::ImplId).collect();
 340         impls
 341     }
 342
 343     fn impl_provided_for(
 344         &self,
 345         auto_trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 346         chalk_ty: &chalk_ir::TyKind<RustInterner<'tcx>>,
 347     ) -> bool {
 348         use chalk_ir::Scalar::*;
 349         use chalk_ir::TyKind::*;
 350
 351         let trait_def_id = auto_trait_id.0;
 352         let all_impls = self.interner.tcx.all_impls(trait_def_id);
 353         for impl_def_id in all_impls {
 354             let trait_ref = self.interner.tcx.impl_trait_ref(impl_def_id).unwrap();
 355             let self_ty = trait_ref.self_ty();
 356             let provides = match (self_ty.kind(), chalk_ty) {
 357                 (&ty::Adt(impl_adt_def, ..), Adt(id, ..)) => impl_adt_def.did == id.0.did,
 358                 (_, AssociatedType(_ty_id, ..)) => {
 359                     // FIXME(chalk): See https://github.com/rust-lang/rust/pull/77152#discussion_r494484774
 360                     false
 361                 }
 362                 (ty::Bool, Scalar(Bool)) => true,
 363                 (ty::Char, Scalar(Char)) => true,
 364                 (ty::Int(ty1), Scalar(Int(ty2))) => matches!(
 365                     (ty1, ty2),
 366                     (ty::IntTy::Isize, chalk_ir::IntTy::Isize)
 367                         | (ty::IntTy::I8, chalk_ir::IntTy::I8)
 368                         | (ty::IntTy::I16, chalk_ir::IntTy::I16)
 369                         | (ty::IntTy::I32, chalk_ir::IntTy::I32)
 370                         | (ty::IntTy::I64, chalk_ir::IntTy::I64)
 371                         | (ty::IntTy::I128, chalk_ir::IntTy::I128)
 372                 ),
 373                 (ty::Uint(ty1), Scalar(Uint(ty2))) => matches!(
 374                     (ty1, ty2),
 375                     (ty::UintTy::Usize, chalk_ir::UintTy::Usize)
 376                         | (ty::UintTy::U8, chalk_ir::UintTy::U8)
 377                         | (ty::UintTy::U16, chalk_ir::UintTy::U16)
 378                         | (ty::UintTy::U32, chalk_ir::UintTy::U32)
 379                         | (ty::UintTy::U64, chalk_ir::UintTy::U64)
 380                         | (ty::UintTy::U128, chalk_ir::UintTy::U128)
 381                 ),
 382                 (ty::Float(ty1), Scalar(Float(ty2))) => matches!(
 383                     (ty1, ty2),
 384                     (ty::FloatTy::F32, chalk_ir::FloatTy::F32)
 385                         | (ty::FloatTy::F64, chalk_ir::FloatTy::F64)
 386                 ),
 387                 (&ty::Tuple(substs), Tuple(len, _)) => substs.len() == *len,
 388                 (&ty::Array(..), Array(..)) => true,
 389                 (&ty::Slice(..), Slice(..)) => true,
 390                 (&ty::RawPtr(type_and_mut), Raw(mutability, _)) => {
 391                     match (type_and_mut.mutbl, mutability) {
 392                         (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true,
 393                         (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false,
 394                         (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false,
 395                         (ast::Mutability::Not, chalk_ir::Mutability::Not) => true,
 396                     }
 397                 }
 398                 (&ty::Ref(.., mutability1), Ref(mutability2, ..)) => {
 399                     match (mutability1, mutability2) {
 400                         (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true,
 401                         (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false,
 402                         (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false,
 403                         (ast::Mutability::Not, chalk_ir::Mutability::Not) => true,
 404                     }
 405                 }
 406                 (&ty::Opaque(def_id, ..), OpaqueType(opaque_ty_id, ..)) => def_id == opaque_ty_id.0,
 407                 (&ty::FnDef(def_id, ..), FnDef(fn_def_id, ..)) => def_id == fn_def_id.0,
 408                 (&ty::Str, Str) => true,
 409                 (&ty::Never, Never) => true,
 410                 (&ty::Closure(def_id, ..), Closure(closure_id, _)) => def_id == closure_id.0,
 411                 (&ty::Foreign(def_id), Foreign(foreign_def_id)) => def_id == foreign_def_id.0,
 412                 (&ty::Error(..), Error) => false,
 413                 _ => false,
 414             };
 415             if provides {
 416                 return true;
 417             }
 418         }
 419         false
 420     }
 421
 422     fn associated_ty_value(
 423         &self,
 424         associated_ty_id: chalk_solve::rust_ir::AssociatedTyValueId<RustInterner<'tcx>>,
 425     ) -> Arc<chalk_solve::rust_ir::AssociatedTyValue<RustInterner<'tcx>>> {
 426         let def_id = associated_ty_id.0;
 427         let assoc_item = self.interner.tcx.associated_item(def_id);
 428         let impl_id = assoc_item.container.id();
 429         match assoc_item.kind {
 430             AssocKind::Type => {}
 431             _ => unimplemented!("Not possible??"),
 432         }
 433
 434         let trait_item_id = assoc_item.trait_item_def_id.expect("assoc_ty with no trait version");
 435         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 436         let binders = binders_for(self.interner, bound_vars);
 437         let ty = self
 438             .interner
 439             .tcx
 440             .type_of(def_id)
 441             .subst(self.interner.tcx, bound_vars)
 442             .lower_into(self.interner);
 443
 444         Arc::new(chalk_solve::rust_ir::AssociatedTyValue {
 445             impl_id: chalk_ir::ImplId(impl_id),
 446             associated_ty_id: chalk_ir::AssocTypeId(trait_item_id),
 447             value: chalk_ir::Binders::new(
 448                 binders,
 449                 chalk_solve::rust_ir::AssociatedTyValueBound { ty },
 450             ),
 451         })
 452     }
 453
 454     fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<RustInterner<'tcx>>> {
 455         vec![]
 456     }
 457
 458     fn local_impls_to_coherence_check(
 459         &self,
 460         _trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 461     ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
 462         unimplemented!()
 463     }
 464
 465     fn opaque_ty_data(
 466         &self,
 467         opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 468     ) -> Arc<chalk_solve::rust_ir::OpaqueTyDatum<RustInterner<'tcx>>> {
 469         let bound_vars = ty::fold::shift_vars(
 470             self.interner.tcx,
 471             bound_vars_for_item(self.interner.tcx, opaque_ty_id.0),
 472             1,
 473         );
 474         let where_clauses = self.where_clauses_for(opaque_ty_id.0, bound_vars);
 475
 476         let identity_substs = InternalSubsts::identity_for_item(self.interner.tcx, opaque_ty_id.0);
 477
 478         let bounds =
 479             self.interner
 480                 .tcx
 481                 .explicit_item_bounds(opaque_ty_id.0)
 482                 .iter()
 483                 .map(|(bound, _)| bound.subst(self.interner.tcx, &bound_vars))
 484                 .map(|bound| {
 485                     bound.fold_with(&mut ReplaceOpaqueTyFolder {
 486                         tcx: self.interner.tcx,
 487                         opaque_ty_id,
 488                         identity_substs,
 489                         binder_index: ty::INNERMOST,
 490                     })
 491                 })
 492                 .filter_map(|bound| {
 493                     LowerInto::<
 494                     Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>
 495                 >::lower_into(bound, self.interner)
 496                 })
 497                 .collect();
 498
 499         // Binder for the bound variable representing the concrete impl Trait type.
 500         let existential_binder = chalk_ir::VariableKinds::from1(
 501             self.interner,
 502             chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
 503         );
 504
 505         let value = chalk_solve::rust_ir::OpaqueTyDatumBound {
 506             bounds: chalk_ir::Binders::new(existential_binder.clone(), bounds),
 507             where_clauses: chalk_ir::Binders::new(existential_binder, where_clauses),
 508         };
 509
 510         let binders = binders_for(self.interner, bound_vars);
 511         Arc::new(chalk_solve::rust_ir::OpaqueTyDatum {
 512             opaque_ty_id,
 513             bound: chalk_ir::Binders::new(binders, value),
 514         })
 515     }
 516
 517     fn program_clauses_for_env(
 518         &self,
 519         environment: &chalk_ir::Environment<RustInterner<'tcx>>,
 520     ) -> chalk_ir::ProgramClauses<RustInterner<'tcx>> {
 521         chalk_solve::program_clauses_for_env(self, environment)
 522     }
 523
 524     fn well_known_trait_id(
 525         &self,
 526         well_known_trait: chalk_solve::rust_ir::WellKnownTrait,
 527     ) -> Option<chalk_ir::TraitId<RustInterner<'tcx>>> {
 528         use chalk_solve::rust_ir::WellKnownTrait::*;
 529         let lang_items = self.interner.tcx.lang_items();
 530         let def_id = match well_known_trait {
 531             Sized => lang_items.sized_trait(),
 532             Copy => lang_items.copy_trait(),
 533             Clone => lang_items.clone_trait(),
 534             Drop => lang_items.drop_trait(),
 535             Fn => lang_items.fn_trait(),
 536             FnMut => lang_items.fn_mut_trait(),
 537             FnOnce => lang_items.fn_once_trait(),
 538             Generator => lang_items.gen_trait(),
 539             Unsize => lang_items.unsize_trait(),
 540             Unpin => lang_items.unpin_trait(),
 541             CoerceUnsized => lang_items.coerce_unsized_trait(),
 542             DiscriminantKind => lang_items.discriminant_kind_trait(),
 543         };
 544         def_id.map(chalk_ir::TraitId)
 545     }
 546
 547     fn is_object_safe(&self, trait_id: chalk_ir::TraitId<RustInterner<'tcx>>) -> bool {
 548         self.interner.tcx.is_object_safe(trait_id.0)
 549     }
 550
 551     fn hidden_opaque_type(
 552         &self,
 553         _id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 554     ) -> chalk_ir::Ty<RustInterner<'tcx>> {
 555         // FIXME(chalk): actually get hidden ty
 556         self.interner
 557             .tcx
 558             .mk_ty(ty::Tuple(self.interner.tcx.intern_type_list(&[])))
 559             .lower_into(self.interner)
 560     }
 561
 562     fn closure_kind(
 563         &self,
 564         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 565         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 566     ) -> chalk_solve::rust_ir::ClosureKind {
 567         let kind = &substs.as_slice(self.interner)[substs.len(self.interner) - 3];
 568         match kind.assert_ty_ref(self.interner).kind(self.interner) {
 569             chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(int_ty)) => match int_ty {
 570                 chalk_ir::IntTy::I8 => chalk_solve::rust_ir::ClosureKind::Fn,
 571                 chalk_ir::IntTy::I16 => chalk_solve::rust_ir::ClosureKind::FnMut,
 572                 chalk_ir::IntTy::I32 => chalk_solve::rust_ir::ClosureKind::FnOnce,
 573                 _ => bug!("bad closure kind"),
 574             },
 575             _ => bug!("bad closure kind"),
 576         }
 577     }
 578
 579     fn closure_inputs_and_output(
 580         &self,
 581         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 582         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 583     ) -> chalk_ir::Binders<chalk_solve::rust_ir::FnDefInputsAndOutputDatum<RustInterner<'tcx>>>
 584     {
 585         let sig = &substs.as_slice(self.interner)[substs.len(self.interner) - 2];
 586         match sig.assert_ty_ref(self.interner).kind(self.interner) {
 587             chalk_ir::TyKind::Function(f) => {
 588                 let substitution = f.substitution.0.as_slice(self.interner);
 589                 let return_type = substitution.last().unwrap().assert_ty_ref(self.interner).clone();
 590                 // Closure arguments are tupled
 591                 let argument_tuple = substitution[0].assert_ty_ref(self.interner);
 592                 let argument_types = match argument_tuple.kind(self.interner) {
 593                     chalk_ir::TyKind::Tuple(_len, substitution) => substitution
 594                         .iter(self.interner)
 595                         .map(|arg| arg.assert_ty_ref(self.interner))
 596                         .cloned()
 597                         .collect(),
 598                     _ => bug!("Expecting closure FnSig args to be tupled."),
 599                 };
 600
 601                 chalk_ir::Binders::new(
 602                     chalk_ir::VariableKinds::from_iter(
 603                         self.interner,
 604                         (0..f.num_binders).map(|_| chalk_ir::VariableKind::Lifetime),
 605                     ),
 606                     chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
 607                 )
 608             }
 609             _ => panic!("Invalid sig."),
 610         }
 611     }
 612
 613     fn closure_upvars(
 614         &self,
 615         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 616         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 617     ) -> chalk_ir::Binders<chalk_ir::Ty<RustInterner<'tcx>>> {
 618         let inputs_and_output = self.closure_inputs_and_output(_closure_id, substs);
 619         let tuple = substs.as_slice(self.interner).last().unwrap().assert_ty_ref(self.interner);
 620         inputs_and_output.map_ref(|_| tuple.clone())
 621     }
 622
 623     fn closure_fn_substitution(
 624         &self,
 625         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 626         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 627     ) -> chalk_ir::Substitution<RustInterner<'tcx>> {
 628         let substitution = &substs.as_slice(self.interner)[0..substs.len(self.interner) - 3];
 629         chalk_ir::Substitution::from_iter(self.interner, substitution)
 630     }
 631
 632     fn generator_datum(
 633         &self,
 634         _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>,
 635     ) -> Arc<chalk_solve::rust_ir::GeneratorDatum<RustInterner<'tcx>>> {
 636         unimplemented!()
 637     }
 638
 639     fn generator_witness_datum(
 640         &self,
 641         _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>,
 642     ) -> Arc<chalk_solve::rust_ir::GeneratorWitnessDatum<RustInterner<'tcx>>> {
 643         unimplemented!()
 644     }
 645
 646     fn unification_database(&self) -> &dyn chalk_ir::UnificationDatabase<RustInterner<'tcx>> {
 647         self
 648     }
 649
 650     fn discriminant_type(
 651         &self,
 652         _: chalk_ir::Ty<RustInterner<'tcx>>,
 653     ) -> chalk_ir::Ty<RustInterner<'tcx>> {
 654         unimplemented!()
 655     }
 656 }
 657
 658 impl<'tcx> chalk_ir::UnificationDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
 659     fn fn_def_variance(
 660         &self,
 661         def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
 662     ) -> chalk_ir::Variances<RustInterner<'tcx>> {
 663         let variances = self.interner.tcx.variances_of(def_id.0);
 664         chalk_ir::Variances::from_iter(
 665             self.interner,
 666             variances.iter().map(|v| v.lower_into(self.interner)),
 667         )
 668     }
 669
 670     fn adt_variance(
 671         &self,
 672         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 673     ) -> chalk_ir::Variances<RustInterner<'tcx>> {
 674         let variances = self.interner.tcx.variances_of(adt_id.0.did);
 675         chalk_ir::Variances::from_iter(
 676             self.interner,
 677             variances.iter().map(|v| v.lower_into(self.interner)),
 678         )
 679     }
 680 }
 681
 682 /// Creates an `InternalSubsts` that maps each generic parameter to a higher-ranked
 683 /// var bound at index `0`. For types, we use a `BoundVar` index equal to
 684 /// the type parameter index. For regions, we use the `BoundRegionKind::BrNamed`
 685 /// variant (which has a `DefId`).
 686 fn bound_vars_for_item<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> SubstsRef<'tcx> {
 687     InternalSubsts::for_item(tcx, def_id, |param, substs| match param.kind {
 688         ty::GenericParamDefKind::Type { .. } => tcx
 689             .mk_ty(ty::Bound(
 690                 ty::INNERMOST,
 691                 ty::BoundTy {
 692                     var: ty::BoundVar::from(param.index),
 693                     kind: ty::BoundTyKind::Param(param.name),
 694                 },
 695             ))
 696             .into(),
 697
 698         ty::GenericParamDefKind::Lifetime => {
 699             let br = ty::BoundRegion {
 700                 var: ty::BoundVar::from_usize(substs.len()),
 701                 kind: ty::BrAnon(substs.len() as u32),
 702             };
 703             tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)).into()
 704         }
 705
 706         ty::GenericParamDefKind::Const { .. } => tcx
 707             .mk_const(ty::ConstS {
 708                 val: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
 709                 ty: tcx.type_of(param.def_id),
 710             })
 711             .into(),
 712     })
 713 }
 714
 715 fn binders_for<'tcx>(
 716     interner: RustInterner<'tcx>,
 717     bound_vars: SubstsRef<'tcx>,
 718 ) -> chalk_ir::VariableKinds<RustInterner<'tcx>> {
 719     chalk_ir::VariableKinds::from_iter(
 720         interner,
 721         bound_vars.iter().map(|arg| match arg.unpack() {
 722             ty::subst::GenericArgKind::Lifetime(_re) => chalk_ir::VariableKind::Lifetime,
 723             ty::subst::GenericArgKind::Type(_ty) => {
 724                 chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General)
 725             }
 726             ty::subst::GenericArgKind::Const(c) => {
 727                 chalk_ir::VariableKind::Const(c.ty().lower_into(interner))
 728             }
 729         }),
 730     )
 731 }
 732
 733 struct ReplaceOpaqueTyFolder<'tcx> {
 734     tcx: TyCtxt<'tcx>,
 735     opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 736     identity_substs: SubstsRef<'tcx>,
 737     binder_index: ty::DebruijnIndex,
 738 }
 739
 740 impl<'tcx> ty::TypeFolder<'tcx> for ReplaceOpaqueTyFolder<'tcx> {
 741     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
 742         self.tcx
 743     }
 744
 745     fn fold_binder<T: TypeFoldable<'tcx>>(
 746         &mut self,
 747         t: ty::Binder<'tcx, T>,
 748     ) -> ty::Binder<'tcx, T> {
 749         self.binder_index.shift_in(1);
 750         let t = t.super_fold_with(self);
 751         self.binder_index.shift_out(1);
 752         t
 753     }
 754
 755     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
 756         if let ty::Opaque(def_id, substs) = *ty.kind() {
 757             if def_id == self.opaque_ty_id.0 && substs == self.identity_substs {
 758                 return self.tcx.mk_ty(ty::Bound(
 759                     self.binder_index,
 760                     ty::BoundTy::from(ty::BoundVar::from_u32(0)),
 761                 ));
 762             }
 763         }
 764         ty
 765     }
 766 }