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::{
  12     self, AssocItemContainer, AssocKind, EarlyBinder, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable,
  13 };
  14
  15 use rustc_ast::ast;
  16 use rustc_attr as attr;
  17
  18 use rustc_hir::def_id::DefId;
  19
  20 use rustc_span::symbol::sym;
  21
  22 use std::fmt;
  23 use std::sync::Arc;
  24
  25 use crate::chalk::lowering::LowerInto;
  26
  27 pub struct RustIrDatabase<'tcx> {
  28     pub(crate) interner: RustInterner<'tcx>,
  29 }
  30
  31 impl fmt::Debug for RustIrDatabase<'_> {
  32     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  33         write!(f, "RustIrDatabase")
  34     }
  35 }
  36
  37 impl<'tcx> RustIrDatabase<'tcx> {
  38     fn where_clauses_for(
  39         &self,
  40         def_id: DefId,
  41         bound_vars: SubstsRef<'tcx>,
  42     ) -> Vec<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> {
  43         let predicates = self.interner.tcx.predicates_defined_on(def_id).predicates;
  44         predicates
  45             .iter()
  46             .map(|(wc, _)| EarlyBinder(*wc).subst(self.interner.tcx, bound_vars))
  47             .filter_map(|wc| LowerInto::<
  48                     Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>
  49                     >::lower_into(wc, self.interner)).collect()
  50     }
  51
  52     fn bounds_for<T>(&self, def_id: DefId, bound_vars: SubstsRef<'tcx>) -> Vec<T>
  53     where
  54         ty::Predicate<'tcx>: LowerInto<'tcx, std::option::Option<T>>,
  55     {
  56         self.interner
  57             .tcx
  58             .explicit_item_bounds(def_id)
  59             .iter()
  60             .map(|(bound, _)| EarlyBinder(*bound).subst(self.interner.tcx, &bound_vars))
  61             .filter_map(|bound| LowerInto::<Option<_>>::lower_into(bound, self.interner))
  62             .collect()
  63     }
  64 }
  65
  66 impl<'tcx> chalk_solve::RustIrDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
  67     fn interner(&self) -> RustInterner<'tcx> {
  68         self.interner
  69     }
  70
  71     fn associated_ty_data(
  72         &self,
  73         assoc_type_id: chalk_ir::AssocTypeId<RustInterner<'tcx>>,
  74     ) -> Arc<chalk_solve::rust_ir::AssociatedTyDatum<RustInterner<'tcx>>> {
  75         let def_id = assoc_type_id.0;
  76         let assoc_item = self.interner.tcx.associated_item(def_id);
  77         let AssocItemContainer::TraitContainer(trait_def_id) = assoc_item.container else {
  78             unimplemented!("Not possible??");
  79         };
  80         match assoc_item.kind {
  81             AssocKind::Type => {}
  82             _ => unimplemented!("Not possible??"),
  83         }
  84         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
  85         let binders = binders_for(self.interner, bound_vars);
  86
  87         let where_clauses = self.where_clauses_for(def_id, bound_vars);
  88         let bounds = self.bounds_for(def_id, bound_vars);
  89
  90         Arc::new(chalk_solve::rust_ir::AssociatedTyDatum {
  91             trait_id: chalk_ir::TraitId(trait_def_id),
  92             id: assoc_type_id,
  93             name: (),
  94             binders: chalk_ir::Binders::new(
  95                 binders,
  96                 chalk_solve::rust_ir::AssociatedTyDatumBound { bounds, where_clauses },
  97             ),
  98         })
  99     }
 100
 101     fn trait_datum(
 102         &self,
 103         trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 104     ) -> Arc<chalk_solve::rust_ir::TraitDatum<RustInterner<'tcx>>> {
 105         use chalk_solve::rust_ir::WellKnownTrait::*;
 106
 107         let def_id = trait_id.0;
 108         let trait_def = self.interner.tcx.trait_def(def_id);
 109
 110         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 111         let binders = binders_for(self.interner, bound_vars);
 112
 113         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 114
 115         let associated_ty_ids: Vec<_> = self
 116             .interner
 117             .tcx
 118             .associated_items(def_id)
 119             .in_definition_order()
 120             .filter(|i| i.kind == AssocKind::Type)
 121             .map(|i| chalk_ir::AssocTypeId(i.def_id))
 122             .collect();
 123
 124         let lang_items = self.interner.tcx.lang_items();
 125         let well_known = if lang_items.sized_trait() == Some(def_id) {
 126             Some(Sized)
 127         } else if lang_items.copy_trait() == Some(def_id) {
 128             Some(Copy)
 129         } else if lang_items.clone_trait() == Some(def_id) {
 130             Some(Clone)
 131         } else if lang_items.drop_trait() == Some(def_id) {
 132             Some(Drop)
 133         } else if lang_items.fn_trait() == Some(def_id) {
 134             Some(Fn)
 135         } else if lang_items.fn_once_trait() == Some(def_id) {
 136             Some(FnOnce)
 137         } else if lang_items.fn_mut_trait() == Some(def_id) {
 138             Some(FnMut)
 139         } else if lang_items.unsize_trait() == Some(def_id) {
 140             Some(Unsize)
 141         } else if lang_items.unpin_trait() == Some(def_id) {
 142             Some(Unpin)
 143         } else if lang_items.coerce_unsized_trait() == Some(def_id) {
 144             Some(CoerceUnsized)
 145         } else if lang_items.dispatch_from_dyn_trait() == Some(def_id) {
 146             Some(DispatchFromDyn)
 147         } else {
 148             None
 149         };
 150         Arc::new(chalk_solve::rust_ir::TraitDatum {
 151             id: trait_id,
 152             binders: chalk_ir::Binders::new(
 153                 binders,
 154                 chalk_solve::rust_ir::TraitDatumBound { where_clauses },
 155             ),
 156             flags: chalk_solve::rust_ir::TraitFlags {
 157                 auto: trait_def.has_auto_impl,
 158                 marker: trait_def.is_marker,
 159                 upstream: !def_id.is_local(),
 160                 fundamental: self.interner.tcx.has_attr(def_id, sym::fundamental),
 161                 non_enumerable: true,
 162                 coinductive: false,
 163             },
 164             associated_ty_ids,
 165             well_known,
 166         })
 167     }
 168
 169     fn adt_datum(
 170         &self,
 171         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 172     ) -> Arc<chalk_solve::rust_ir::AdtDatum<RustInterner<'tcx>>> {
 173         let adt_def = adt_id.0;
 174
 175         let bound_vars = bound_vars_for_item(self.interner.tcx, adt_def.did());
 176         let binders = binders_for(self.interner, bound_vars);
 177
 178         let where_clauses = self.where_clauses_for(adt_def.did(), bound_vars);
 179
 180         let variants: Vec<_> = adt_def
 181             .variants()
 182             .iter()
 183             .map(|variant| chalk_solve::rust_ir::AdtVariantDatum {
 184                 fields: variant
 185                     .fields
 186                     .iter()
 187                     .map(|field| field.ty(self.interner.tcx, bound_vars).lower_into(self.interner))
 188                     .collect(),
 189             })
 190             .collect();
 191         Arc::new(chalk_solve::rust_ir::AdtDatum {
 192             id: adt_id,
 193             binders: chalk_ir::Binders::new(
 194                 binders,
 195                 chalk_solve::rust_ir::AdtDatumBound { variants, where_clauses },
 196             ),
 197             flags: chalk_solve::rust_ir::AdtFlags {
 198                 upstream: !adt_def.did().is_local(),
 199                 fundamental: adt_def.is_fundamental(),
 200                 phantom_data: adt_def.is_phantom_data(),
 201             },
 202             kind: match adt_def.adt_kind() {
 203                 ty::AdtKind::Struct => chalk_solve::rust_ir::AdtKind::Struct,
 204                 ty::AdtKind::Union => chalk_solve::rust_ir::AdtKind::Union,
 205                 ty::AdtKind::Enum => chalk_solve::rust_ir::AdtKind::Enum,
 206             },
 207         })
 208     }
 209
 210     fn adt_repr(
 211         &self,
 212         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 213     ) -> Arc<chalk_solve::rust_ir::AdtRepr<RustInterner<'tcx>>> {
 214         let adt_def = adt_id.0;
 215         let int = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(i)).intern(self.interner);
 216         let uint = |i| chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Uint(i)).intern(self.interner);
 217         Arc::new(chalk_solve::rust_ir::AdtRepr {
 218             c: adt_def.repr().c(),
 219             packed: adt_def.repr().packed(),
 220             int: adt_def.repr().int.map(|i| match i {
 221                 attr::IntType::SignedInt(ty) => match ty {
 222                     ast::IntTy::Isize => int(chalk_ir::IntTy::Isize),
 223                     ast::IntTy::I8 => int(chalk_ir::IntTy::I8),
 224                     ast::IntTy::I16 => int(chalk_ir::IntTy::I16),
 225                     ast::IntTy::I32 => int(chalk_ir::IntTy::I32),
 226                     ast::IntTy::I64 => int(chalk_ir::IntTy::I64),
 227                     ast::IntTy::I128 => int(chalk_ir::IntTy::I128),
 228                 },
 229                 attr::IntType::UnsignedInt(ty) => match ty {
 230                     ast::UintTy::Usize => uint(chalk_ir::UintTy::Usize),
 231                     ast::UintTy::U8 => uint(chalk_ir::UintTy::U8),
 232                     ast::UintTy::U16 => uint(chalk_ir::UintTy::U16),
 233                     ast::UintTy::U32 => uint(chalk_ir::UintTy::U32),
 234                     ast::UintTy::U64 => uint(chalk_ir::UintTy::U64),
 235                     ast::UintTy::U128 => uint(chalk_ir::UintTy::U128),
 236                 },
 237             }),
 238         })
 239     }
 240
 241     fn adt_size_align(
 242         &self,
 243         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 244     ) -> Arc<chalk_solve::rust_ir::AdtSizeAlign> {
 245         let tcx = self.interner.tcx;
 246         let did = adt_id.0.did();
 247
 248         // Grab the ADT and the param we might need to calculate its layout
 249         let param_env = tcx.param_env(did);
 250         let adt_ty = tcx.type_of(did);
 251
 252         // The ADT is a 1-zst if it's a ZST and its alignment is 1.
 253         // Mark the ADT as _not_ a 1-zst if there was a layout error.
 254         let one_zst = if let Ok(layout) = tcx.layout_of(param_env.and(adt_ty)) {
 255             layout.is_zst() && layout.align.abi.bytes() == 1
 256         } else {
 257             false
 258         };
 259
 260         Arc::new(chalk_solve::rust_ir::AdtSizeAlign::from_one_zst(one_zst))
 261     }
 262
 263     fn fn_def_datum(
 264         &self,
 265         fn_def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
 266     ) -> Arc<chalk_solve::rust_ir::FnDefDatum<RustInterner<'tcx>>> {
 267         let def_id = fn_def_id.0;
 268         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 269         let binders = binders_for(self.interner, bound_vars);
 270
 271         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 272
 273         let sig = self.interner.tcx.fn_sig(def_id);
 274         let (inputs_and_output, iobinders, _) = crate::chalk::lowering::collect_bound_vars(
 275             self.interner,
 276             self.interner.tcx,
 277             EarlyBinder(sig.inputs_and_output()).subst(self.interner.tcx, bound_vars),
 278         );
 279
 280         let argument_types = inputs_and_output[..inputs_and_output.len() - 1]
 281             .iter()
 282             .map(|t| {
 283                 EarlyBinder(*t).subst(self.interner.tcx, &bound_vars).lower_into(self.interner)
 284             })
 285             .collect();
 286
 287         let return_type = EarlyBinder(inputs_and_output[inputs_and_output.len() - 1])
 288             .subst(self.interner.tcx, &bound_vars)
 289             .lower_into(self.interner);
 290
 291         let bound = chalk_solve::rust_ir::FnDefDatumBound {
 292             inputs_and_output: chalk_ir::Binders::new(
 293                 iobinders,
 294                 chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
 295             ),
 296             where_clauses,
 297         };
 298         Arc::new(chalk_solve::rust_ir::FnDefDatum {
 299             id: fn_def_id,
 300             sig: sig.lower_into(self.interner),
 301             binders: chalk_ir::Binders::new(binders, bound),
 302         })
 303     }
 304
 305     fn impl_datum(
 306         &self,
 307         impl_id: chalk_ir::ImplId<RustInterner<'tcx>>,
 308     ) -> Arc<chalk_solve::rust_ir::ImplDatum<RustInterner<'tcx>>> {
 309         let def_id = impl_id.0;
 310         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 311         let binders = binders_for(self.interner, bound_vars);
 312
 313         let trait_ref = self.interner.tcx.bound_impl_trait_ref(def_id).expect("not an impl");
 314         let trait_ref = trait_ref.subst(self.interner.tcx, bound_vars);
 315
 316         let where_clauses = self.where_clauses_for(def_id, bound_vars);
 317
 318         let value = chalk_solve::rust_ir::ImplDatumBound {
 319             trait_ref: trait_ref.lower_into(self.interner),
 320             where_clauses,
 321         };
 322
 323         let associated_ty_value_ids: Vec<_> = self
 324             .interner
 325             .tcx
 326             .associated_items(def_id)
 327             .in_definition_order()
 328             .filter(|i| i.kind == AssocKind::Type)
 329             .map(|i| chalk_solve::rust_ir::AssociatedTyValueId(i.def_id))
 330             .collect();
 331
 332         Arc::new(chalk_solve::rust_ir::ImplDatum {
 333             polarity: self.interner.tcx.impl_polarity(def_id).lower_into(self.interner),
 334             binders: chalk_ir::Binders::new(binders, value),
 335             impl_type: chalk_solve::rust_ir::ImplType::Local,
 336             associated_ty_value_ids,
 337         })
 338     }
 339
 340     fn impls_for_trait(
 341         &self,
 342         trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 343         parameters: &[chalk_ir::GenericArg<RustInterner<'tcx>>],
 344         _binders: &chalk_ir::CanonicalVarKinds<RustInterner<'tcx>>,
 345     ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
 346         let def_id = trait_id.0;
 347
 348         // FIXME(chalk): use TraitDef::for_each_relevant_impl, but that will
 349         // require us to be able to interconvert `Ty<'tcx>`, and we're
 350         // not there yet.
 351
 352         let all_impls = self.interner.tcx.all_impls(def_id);
 353         let matched_impls = all_impls.filter(|impl_def_id| {
 354             use chalk_ir::could_match::CouldMatch;
 355             let trait_ref = self.interner.tcx.bound_impl_trait_ref(*impl_def_id).unwrap();
 356             let bound_vars = bound_vars_for_item(self.interner.tcx, *impl_def_id);
 357
 358             let self_ty = trait_ref.map_bound(|t| t.self_ty());
 359             let self_ty = self_ty.subst(self.interner.tcx, bound_vars);
 360             let lowered_ty = self_ty.lower_into(self.interner);
 361
 362             parameters[0].assert_ty_ref(self.interner).could_match(
 363                 self.interner,
 364                 self.unification_database(),
 365                 &lowered_ty,
 366             )
 367         });
 368
 369         let impls = matched_impls.map(chalk_ir::ImplId).collect();
 370         impls
 371     }
 372
 373     fn impl_provided_for(
 374         &self,
 375         auto_trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 376         chalk_ty: &chalk_ir::TyKind<RustInterner<'tcx>>,
 377     ) -> bool {
 378         use chalk_ir::Scalar::*;
 379         use chalk_ir::TyKind::*;
 380
 381         let trait_def_id = auto_trait_id.0;
 382         let all_impls = self.interner.tcx.all_impls(trait_def_id);
 383         for impl_def_id in all_impls {
 384             let trait_ref = self.interner.tcx.impl_trait_ref(impl_def_id).unwrap();
 385             let self_ty = trait_ref.self_ty();
 386             let provides = match (self_ty.kind(), chalk_ty) {
 387                 (&ty::Adt(impl_adt_def, ..), Adt(id, ..)) => impl_adt_def.did() == id.0.did(),
 388                 (_, AssociatedType(_ty_id, ..)) => {
 389                     // FIXME(chalk): See https://github.com/rust-lang/rust/pull/77152#discussion_r494484774
 390                     false
 391                 }
 392                 (ty::Bool, Scalar(Bool)) => true,
 393                 (ty::Char, Scalar(Char)) => true,
 394                 (ty::Int(ty1), Scalar(Int(ty2))) => matches!(
 395                     (ty1, ty2),
 396                     (ty::IntTy::Isize, chalk_ir::IntTy::Isize)
 397                         | (ty::IntTy::I8, chalk_ir::IntTy::I8)
 398                         | (ty::IntTy::I16, chalk_ir::IntTy::I16)
 399                         | (ty::IntTy::I32, chalk_ir::IntTy::I32)
 400                         | (ty::IntTy::I64, chalk_ir::IntTy::I64)
 401                         | (ty::IntTy::I128, chalk_ir::IntTy::I128)
 402                 ),
 403                 (ty::Uint(ty1), Scalar(Uint(ty2))) => matches!(
 404                     (ty1, ty2),
 405                     (ty::UintTy::Usize, chalk_ir::UintTy::Usize)
 406                         | (ty::UintTy::U8, chalk_ir::UintTy::U8)
 407                         | (ty::UintTy::U16, chalk_ir::UintTy::U16)
 408                         | (ty::UintTy::U32, chalk_ir::UintTy::U32)
 409                         | (ty::UintTy::U64, chalk_ir::UintTy::U64)
 410                         | (ty::UintTy::U128, chalk_ir::UintTy::U128)
 411                 ),
 412                 (ty::Float(ty1), Scalar(Float(ty2))) => matches!(
 413                     (ty1, ty2),
 414                     (ty::FloatTy::F32, chalk_ir::FloatTy::F32)
 415                         | (ty::FloatTy::F64, chalk_ir::FloatTy::F64)
 416                 ),
 417                 (&ty::Tuple(substs), Tuple(len, _)) => substs.len() == *len,
 418                 (&ty::Array(..), Array(..)) => true,
 419                 (&ty::Slice(..), Slice(..)) => true,
 420                 (&ty::RawPtr(type_and_mut), Raw(mutability, _)) => {
 421                     match (type_and_mut.mutbl, mutability) {
 422                         (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true,
 423                         (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false,
 424                         (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false,
 425                         (ast::Mutability::Not, chalk_ir::Mutability::Not) => true,
 426                     }
 427                 }
 428                 (&ty::Ref(.., mutability1), Ref(mutability2, ..)) => {
 429                     match (mutability1, mutability2) {
 430                         (ast::Mutability::Mut, chalk_ir::Mutability::Mut) => true,
 431                         (ast::Mutability::Mut, chalk_ir::Mutability::Not) => false,
 432                         (ast::Mutability::Not, chalk_ir::Mutability::Mut) => false,
 433                         (ast::Mutability::Not, chalk_ir::Mutability::Not) => true,
 434                     }
 435                 }
 436                 (&ty::Opaque(def_id, ..), OpaqueType(opaque_ty_id, ..)) => def_id == opaque_ty_id.0,
 437                 (&ty::FnDef(def_id, ..), FnDef(fn_def_id, ..)) => def_id == fn_def_id.0,
 438                 (&ty::Str, Str) => true,
 439                 (&ty::Never, Never) => true,
 440                 (&ty::Closure(def_id, ..), Closure(closure_id, _)) => def_id == closure_id.0,
 441                 (&ty::Foreign(def_id), Foreign(foreign_def_id)) => def_id == foreign_def_id.0,
 442                 (&ty::Error(..), Error) => false,
 443                 _ => false,
 444             };
 445             if provides {
 446                 return true;
 447             }
 448         }
 449         false
 450     }
 451
 452     fn associated_ty_value(
 453         &self,
 454         associated_ty_id: chalk_solve::rust_ir::AssociatedTyValueId<RustInterner<'tcx>>,
 455     ) -> Arc<chalk_solve::rust_ir::AssociatedTyValue<RustInterner<'tcx>>> {
 456         let def_id = associated_ty_id.0;
 457         let assoc_item = self.interner.tcx.associated_item(def_id);
 458         let impl_id = assoc_item.container.id();
 459         match assoc_item.kind {
 460             AssocKind::Type => {}
 461             _ => unimplemented!("Not possible??"),
 462         }
 463
 464         let trait_item_id = assoc_item.trait_item_def_id.expect("assoc_ty with no trait version");
 465         let bound_vars = bound_vars_for_item(self.interner.tcx, def_id);
 466         let binders = binders_for(self.interner, bound_vars);
 467         let ty = self
 468             .interner
 469             .tcx
 470             .bound_type_of(def_id)
 471             .subst(self.interner.tcx, bound_vars)
 472             .lower_into(self.interner);
 473
 474         Arc::new(chalk_solve::rust_ir::AssociatedTyValue {
 475             impl_id: chalk_ir::ImplId(impl_id),
 476             associated_ty_id: chalk_ir::AssocTypeId(trait_item_id),
 477             value: chalk_ir::Binders::new(
 478                 binders,
 479                 chalk_solve::rust_ir::AssociatedTyValueBound { ty },
 480             ),
 481         })
 482     }
 483
 484     fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<RustInterner<'tcx>>> {
 485         vec![]
 486     }
 487
 488     fn local_impls_to_coherence_check(
 489         &self,
 490         _trait_id: chalk_ir::TraitId<RustInterner<'tcx>>,
 491     ) -> Vec<chalk_ir::ImplId<RustInterner<'tcx>>> {
 492         unimplemented!()
 493     }
 494
 495     fn opaque_ty_data(
 496         &self,
 497         opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 498     ) -> Arc<chalk_solve::rust_ir::OpaqueTyDatum<RustInterner<'tcx>>> {
 499         let bound_vars = ty::fold::shift_vars(
 500             self.interner.tcx,
 501             bound_vars_for_item(self.interner.tcx, opaque_ty_id.0),
 502             1,
 503         );
 504         let where_clauses = self.where_clauses_for(opaque_ty_id.0, bound_vars);
 505
 506         let identity_substs = InternalSubsts::identity_for_item(self.interner.tcx, opaque_ty_id.0);
 507
 508         let bounds =
 509             self.interner
 510                 .tcx
 511                 .explicit_item_bounds(opaque_ty_id.0)
 512                 .iter()
 513                 .map(|(bound, _)| EarlyBinder(*bound).subst(self.interner.tcx, &bound_vars))
 514                 .map(|bound| {
 515                     bound.fold_with(&mut ReplaceOpaqueTyFolder {
 516                         tcx: self.interner.tcx,
 517                         opaque_ty_id,
 518                         identity_substs,
 519                         binder_index: ty::INNERMOST,
 520                     })
 521                 })
 522                 .filter_map(|bound| {
 523                     LowerInto::<
 524                     Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>>
 525                 >::lower_into(bound, self.interner)
 526                 })
 527                 .collect();
 528
 529         // Binder for the bound variable representing the concrete impl Trait type.
 530         let existential_binder = chalk_ir::VariableKinds::from1(
 531             self.interner,
 532             chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
 533         );
 534
 535         let value = chalk_solve::rust_ir::OpaqueTyDatumBound {
 536             bounds: chalk_ir::Binders::new(existential_binder.clone(), bounds),
 537             where_clauses: chalk_ir::Binders::new(existential_binder, where_clauses),
 538         };
 539
 540         let binders = binders_for(self.interner, bound_vars);
 541         Arc::new(chalk_solve::rust_ir::OpaqueTyDatum {
 542             opaque_ty_id,
 543             bound: chalk_ir::Binders::new(binders, value),
 544         })
 545     }
 546
 547     fn program_clauses_for_env(
 548         &self,
 549         environment: &chalk_ir::Environment<RustInterner<'tcx>>,
 550     ) -> chalk_ir::ProgramClauses<RustInterner<'tcx>> {
 551         chalk_solve::program_clauses_for_env(self, environment)
 552     }
 553
 554     fn well_known_trait_id(
 555         &self,
 556         well_known_trait: chalk_solve::rust_ir::WellKnownTrait,
 557     ) -> Option<chalk_ir::TraitId<RustInterner<'tcx>>> {
 558         use chalk_solve::rust_ir::WellKnownTrait::*;
 559         let lang_items = self.interner.tcx.lang_items();
 560         let def_id = match well_known_trait {
 561             Sized => lang_items.sized_trait(),
 562             Copy => lang_items.copy_trait(),
 563             Clone => lang_items.clone_trait(),
 564             Drop => lang_items.drop_trait(),
 565             Fn => lang_items.fn_trait(),
 566             FnMut => lang_items.fn_mut_trait(),
 567             FnOnce => lang_items.fn_once_trait(),
 568             Generator => lang_items.gen_trait(),
 569             Unsize => lang_items.unsize_trait(),
 570             Unpin => lang_items.unpin_trait(),
 571             CoerceUnsized => lang_items.coerce_unsized_trait(),
 572             DiscriminantKind => lang_items.discriminant_kind_trait(),
 573             DispatchFromDyn => lang_items.dispatch_from_dyn_trait(),
 574         };
 575         def_id.map(chalk_ir::TraitId)
 576     }
 577
 578     fn is_object_safe(&self, trait_id: chalk_ir::TraitId<RustInterner<'tcx>>) -> bool {
 579         self.interner.tcx.is_object_safe(trait_id.0)
 580     }
 581
 582     fn hidden_opaque_type(
 583         &self,
 584         _id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 585     ) -> chalk_ir::Ty<RustInterner<'tcx>> {
 586         // FIXME(chalk): actually get hidden ty
 587         self.interner
 588             .tcx
 589             .mk_ty(ty::Tuple(self.interner.tcx.intern_type_list(&[])))
 590             .lower_into(self.interner)
 591     }
 592
 593     fn closure_kind(
 594         &self,
 595         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 596         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 597     ) -> chalk_solve::rust_ir::ClosureKind {
 598         let kind = &substs.as_slice(self.interner)[substs.len(self.interner) - 3];
 599         match kind.assert_ty_ref(self.interner).kind(self.interner) {
 600             chalk_ir::TyKind::Scalar(chalk_ir::Scalar::Int(int_ty)) => match int_ty {
 601                 chalk_ir::IntTy::I8 => chalk_solve::rust_ir::ClosureKind::Fn,
 602                 chalk_ir::IntTy::I16 => chalk_solve::rust_ir::ClosureKind::FnMut,
 603                 chalk_ir::IntTy::I32 => chalk_solve::rust_ir::ClosureKind::FnOnce,
 604                 _ => bug!("bad closure kind"),
 605             },
 606             _ => bug!("bad closure kind"),
 607         }
 608     }
 609
 610     fn closure_inputs_and_output(
 611         &self,
 612         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 613         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 614     ) -> chalk_ir::Binders<chalk_solve::rust_ir::FnDefInputsAndOutputDatum<RustInterner<'tcx>>>
 615     {
 616         let sig = &substs.as_slice(self.interner)[substs.len(self.interner) - 2];
 617         match sig.assert_ty_ref(self.interner).kind(self.interner) {
 618             chalk_ir::TyKind::Function(f) => {
 619                 let substitution = f.substitution.0.as_slice(self.interner);
 620                 let return_type = substitution.last().unwrap().assert_ty_ref(self.interner).clone();
 621                 // Closure arguments are tupled
 622                 let argument_tuple = substitution[0].assert_ty_ref(self.interner);
 623                 let argument_types = match argument_tuple.kind(self.interner) {
 624                     chalk_ir::TyKind::Tuple(_len, substitution) => substitution
 625                         .iter(self.interner)
 626                         .map(|arg| arg.assert_ty_ref(self.interner))
 627                         .cloned()
 628                         .collect(),
 629                     _ => bug!("Expecting closure FnSig args to be tupled."),
 630                 };
 631
 632                 chalk_ir::Binders::new(
 633                     chalk_ir::VariableKinds::from_iter(
 634                         self.interner,
 635                         (0..f.num_binders).map(|_| chalk_ir::VariableKind::Lifetime),
 636                     ),
 637                     chalk_solve::rust_ir::FnDefInputsAndOutputDatum { argument_types, return_type },
 638                 )
 639             }
 640             _ => panic!("Invalid sig."),
 641         }
 642     }
 643
 644     fn closure_upvars(
 645         &self,
 646         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 647         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 648     ) -> chalk_ir::Binders<chalk_ir::Ty<RustInterner<'tcx>>> {
 649         let inputs_and_output = self.closure_inputs_and_output(_closure_id, substs);
 650         let tuple = substs.as_slice(self.interner).last().unwrap().assert_ty_ref(self.interner);
 651         inputs_and_output.map_ref(|_| tuple.clone())
 652     }
 653
 654     fn closure_fn_substitution(
 655         &self,
 656         _closure_id: chalk_ir::ClosureId<RustInterner<'tcx>>,
 657         substs: &chalk_ir::Substitution<RustInterner<'tcx>>,
 658     ) -> chalk_ir::Substitution<RustInterner<'tcx>> {
 659         let substitution = &substs.as_slice(self.interner)[0..substs.len(self.interner) - 3];
 660         chalk_ir::Substitution::from_iter(self.interner, substitution)
 661     }
 662
 663     fn generator_datum(
 664         &self,
 665         _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>,
 666     ) -> Arc<chalk_solve::rust_ir::GeneratorDatum<RustInterner<'tcx>>> {
 667         unimplemented!()
 668     }
 669
 670     fn generator_witness_datum(
 671         &self,
 672         _generator_id: chalk_ir::GeneratorId<RustInterner<'tcx>>,
 673     ) -> Arc<chalk_solve::rust_ir::GeneratorWitnessDatum<RustInterner<'tcx>>> {
 674         unimplemented!()
 675     }
 676
 677     fn unification_database(&self) -> &dyn chalk_ir::UnificationDatabase<RustInterner<'tcx>> {
 678         self
 679     }
 680
 681     fn discriminant_type(
 682         &self,
 683         _: chalk_ir::Ty<RustInterner<'tcx>>,
 684     ) -> chalk_ir::Ty<RustInterner<'tcx>> {
 685         unimplemented!()
 686     }
 687 }
 688
 689 impl<'tcx> chalk_ir::UnificationDatabase<RustInterner<'tcx>> for RustIrDatabase<'tcx> {
 690     fn fn_def_variance(
 691         &self,
 692         def_id: chalk_ir::FnDefId<RustInterner<'tcx>>,
 693     ) -> chalk_ir::Variances<RustInterner<'tcx>> {
 694         let variances = self.interner.tcx.variances_of(def_id.0);
 695         chalk_ir::Variances::from_iter(
 696             self.interner,
 697             variances.iter().map(|v| v.lower_into(self.interner)),
 698         )
 699     }
 700
 701     fn adt_variance(
 702         &self,
 703         adt_id: chalk_ir::AdtId<RustInterner<'tcx>>,
 704     ) -> chalk_ir::Variances<RustInterner<'tcx>> {
 705         let variances = self.interner.tcx.variances_of(adt_id.0.did());
 706         chalk_ir::Variances::from_iter(
 707             self.interner,
 708             variances.iter().map(|v| v.lower_into(self.interner)),
 709         )
 710     }
 711 }
 712
 713 /// Creates an `InternalSubsts` that maps each generic parameter to a higher-ranked
 714 /// var bound at index `0`. For types, we use a `BoundVar` index equal to
 715 /// the type parameter index. For regions, we use the `BoundRegionKind::BrNamed`
 716 /// variant (which has a `DefId`).
 717 fn bound_vars_for_item<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> SubstsRef<'tcx> {
 718     InternalSubsts::for_item(tcx, def_id, |param, substs| match param.kind {
 719         ty::GenericParamDefKind::Type { .. } => tcx
 720             .mk_ty(ty::Bound(
 721                 ty::INNERMOST,
 722                 ty::BoundTy {
 723                     var: ty::BoundVar::from(param.index),
 724                     kind: ty::BoundTyKind::Param(param.name),
 725                 },
 726             ))
 727             .into(),
 728
 729         ty::GenericParamDefKind::Lifetime => {
 730             let br = ty::BoundRegion {
 731                 var: ty::BoundVar::from_usize(substs.len()),
 732                 kind: ty::BrAnon(substs.len() as u32),
 733             };
 734             tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)).into()
 735         }
 736
 737         ty::GenericParamDefKind::Const { .. } => tcx
 738             .mk_const(ty::ConstS {
 739                 kind: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
 740                 ty: tcx.type_of(param.def_id),
 741             })
 742             .into(),
 743     })
 744 }
 745
 746 fn binders_for<'tcx>(
 747     interner: RustInterner<'tcx>,
 748     bound_vars: SubstsRef<'tcx>,
 749 ) -> chalk_ir::VariableKinds<RustInterner<'tcx>> {
 750     chalk_ir::VariableKinds::from_iter(
 751         interner,
 752         bound_vars.iter().map(|arg| match arg.unpack() {
 753             ty::subst::GenericArgKind::Lifetime(_re) => chalk_ir::VariableKind::Lifetime,
 754             ty::subst::GenericArgKind::Type(_ty) => {
 755                 chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General)
 756             }
 757             ty::subst::GenericArgKind::Const(c) => {
 758                 chalk_ir::VariableKind::Const(c.ty().lower_into(interner))
 759             }
 760         }),
 761     )
 762 }
 763
 764 struct ReplaceOpaqueTyFolder<'tcx> {
 765     tcx: TyCtxt<'tcx>,
 766     opaque_ty_id: chalk_ir::OpaqueTyId<RustInterner<'tcx>>,
 767     identity_substs: SubstsRef<'tcx>,
 768     binder_index: ty::DebruijnIndex,
 769 }
 770
 771 impl<'tcx> ty::TypeFolder<'tcx> for ReplaceOpaqueTyFolder<'tcx> {
 772     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
 773         self.tcx
 774     }
 775
 776     fn fold_binder<T: TypeFoldable<'tcx>>(
 777         &mut self,
 778         t: ty::Binder<'tcx, T>,
 779     ) -> ty::Binder<'tcx, T> {
 780         self.binder_index.shift_in(1);
 781         let t = t.super_fold_with(self);
 782         self.binder_index.shift_out(1);
 783         t
 784     }
 785
 786     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
 787         if let ty::Opaque(def_id, substs) = *ty.kind() {
 788             if def_id == self.opaque_ty_id.0 && substs == self.identity_substs {
 789                 return self.tcx.mk_ty(ty::Bound(
 790                     self.binder_index,
 791                     ty::BoundTy::from(ty::BoundVar::from_u32(0)),
 792                 ));
 793             }
 794         }
 795         ty
 796     }
 797 }