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