compiler/rustc_typeck/src/check/writeback.rs

   1 // Type resolution: the phase that finds all the types in the AST with
   2 // unresolved type variables and replaces "ty_var" types with their
   3 // substitutions.
   4
   5 use crate::check::FnCtxt;
   6
   7 use hir::def_id::LocalDefId;
   8 use rustc_data_structures::fx::FxHashMap;
   9 use rustc_errors::ErrorGuaranteed;
  10 use rustc_hir as hir;
  11 use rustc_hir::intravisit::{self, Visitor};
  12 use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
  13 use rustc_infer::infer::InferCtxt;
  14 use rustc_middle::hir::place::Place as HirPlace;
  15 use rustc_middle::mir::FakeReadCause;
  16 use rustc_middle::ty::adjustment::{Adjust, Adjustment, PointerCast};
  17 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
  18 use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable};
  19 use rustc_middle::ty::{self, ClosureSizeProfileData, Ty, TyCtxt};
  20 use rustc_span::symbol::sym;
  21 use rustc_span::Span;
  22
  23 use std::mem;
  24 use std::ops::ControlFlow;
  25
  26 ///////////////////////////////////////////////////////////////////////////
  27 // Entry point
  28
  29 // During type inference, partially inferred types are
  30 // represented using Type variables (ty::Infer). These don't appear in
  31 // the final TypeckResults since all of the types should have been
  32 // inferred once typeck is done.
  33 // When type inference is running however, having to update the typeck
  34 // typeck results every time a new type is inferred would be unreasonably slow,
  35 // so instead all of the replacement happens at the end in
  36 // resolve_type_vars_in_body, which creates a new TypeTables which
  37 // doesn't contain any inference types.
  38 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  39     pub fn resolve_type_vars_in_body(
  40         &self,
  41         body: &'tcx hir::Body<'tcx>,
  42     ) -> &'tcx ty::TypeckResults<'tcx> {
  43         let item_id = self.tcx.hir().body_owner(body.id());
  44         let item_def_id = self.tcx.hir().local_def_id(item_id);
  45
  46         // This attribute causes us to dump some writeback information
  47         // in the form of errors, which is used for unit tests.
  48         let rustc_dump_user_substs =
  49             self.tcx.has_attr(item_def_id.to_def_id(), sym::rustc_dump_user_substs);
  50
  51         let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_substs);
  52         for param in body.params {
  53             wbcx.visit_node_id(param.pat.span, param.hir_id);
  54         }
  55         // Type only exists for constants and statics, not functions.
  56         match self.tcx.hir().body_owner_kind(item_def_id) {
  57             hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => {
  58                 wbcx.visit_node_id(body.value.span, item_id);
  59             }
  60             hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => (),
  61         }
  62         wbcx.visit_body(body);
  63         wbcx.visit_min_capture_map();
  64         wbcx.eval_closure_size();
  65         wbcx.visit_fake_reads_map();
  66         wbcx.visit_closures();
  67         wbcx.visit_liberated_fn_sigs();
  68         wbcx.visit_fru_field_types();
  69         wbcx.visit_opaque_types();
  70         wbcx.visit_coercion_casts();
  71         wbcx.visit_user_provided_tys();
  72         wbcx.visit_user_provided_sigs();
  73         wbcx.visit_generator_interior_types();
  74
  75         wbcx.typeck_results.rvalue_scopes =
  76             mem::take(&mut self.typeck_results.borrow_mut().rvalue_scopes);
  77
  78         let used_trait_imports =
  79             mem::take(&mut self.typeck_results.borrow_mut().used_trait_imports);
  80         debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
  81         wbcx.typeck_results.used_trait_imports = used_trait_imports;
  82
  83         wbcx.typeck_results.treat_byte_string_as_slice =
  84             mem::take(&mut self.typeck_results.borrow_mut().treat_byte_string_as_slice);
  85
  86         if self.is_tainted_by_errors() {
  87             // FIXME(eddyb) keep track of `ErrorGuaranteed` from where the error was emitted.
  88             wbcx.typeck_results.tainted_by_errors =
  89                 Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
  90         }
  91
  92         debug!("writeback: typeck results for {:?} are {:#?}", item_def_id, wbcx.typeck_results);
  93
  94         self.tcx.arena.alloc(wbcx.typeck_results)
  95     }
  96 }
  97
  98 ///////////////////////////////////////////////////////////////////////////
  99 // The Writeback context. This visitor walks the HIR, checking the
 100 // fn-specific typeck results to find references to types or regions. It
 101 // resolves those regions to remove inference variables and writes the
 102 // final result back into the master typeck results in the tcx. Here and
 103 // there, it applies a few ad-hoc checks that were not convenient to
 104 // do elsewhere.
 105
 106 struct WritebackCx<'cx, 'tcx> {
 107     fcx: &'cx FnCtxt<'cx, 'tcx>,
 108
 109     typeck_results: ty::TypeckResults<'tcx>,
 110
 111     body: &'tcx hir::Body<'tcx>,
 112
 113     rustc_dump_user_substs: bool,
 114 }
 115
 116 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
 117     fn new(
 118         fcx: &'cx FnCtxt<'cx, 'tcx>,
 119         body: &'tcx hir::Body<'tcx>,
 120         rustc_dump_user_substs: bool,
 121     ) -> WritebackCx<'cx, 'tcx> {
 122         let owner = body.id().hir_id.owner;
 123
 124         WritebackCx {
 125             fcx,
 126             typeck_results: ty::TypeckResults::new(owner),
 127             body,
 128             rustc_dump_user_substs,
 129         }
 130     }
 131
 132     fn tcx(&self) -> TyCtxt<'tcx> {
 133         self.fcx.tcx
 134     }
 135
 136     fn write_ty_to_typeck_results(&mut self, hir_id: hir::HirId, ty: Ty<'tcx>) {
 137         debug!("write_ty_to_typeck_results({:?}, {:?})", hir_id, ty);
 138         assert!(!ty.needs_infer() && !ty.has_placeholders() && !ty.has_free_regions());
 139         self.typeck_results.node_types_mut().insert(hir_id, ty);
 140     }
 141
 142     // Hacky hack: During type-checking, we treat *all* operators
 143     // as potentially overloaded. But then, during writeback, if
 144     // we observe that something like `a+b` is (known to be)
 145     // operating on scalars, we clear the overload.
 146     fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr<'_>) {
 147         match e.kind {
 148             hir::ExprKind::Unary(hir::UnOp::Neg | hir::UnOp::Not, inner) => {
 149                 let inner_ty = self.fcx.node_ty(inner.hir_id);
 150                 let inner_ty = self.fcx.resolve_vars_if_possible(inner_ty);
 151
 152                 if inner_ty.is_scalar() {
 153                     let mut typeck_results = self.fcx.typeck_results.borrow_mut();
 154                     typeck_results.type_dependent_defs_mut().remove(e.hir_id);
 155                     typeck_results.node_substs_mut().remove(e.hir_id);
 156                 }
 157             }
 158             hir::ExprKind::Binary(ref op, lhs, rhs) | hir::ExprKind::AssignOp(ref op, lhs, rhs) => {
 159                 let lhs_ty = self.fcx.node_ty(lhs.hir_id);
 160                 let lhs_ty = self.fcx.resolve_vars_if_possible(lhs_ty);
 161
 162                 let rhs_ty = self.fcx.node_ty(rhs.hir_id);
 163                 let rhs_ty = self.fcx.resolve_vars_if_possible(rhs_ty);
 164
 165                 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
 166                     let mut typeck_results = self.fcx.typeck_results.borrow_mut();
 167                     typeck_results.type_dependent_defs_mut().remove(e.hir_id);
 168                     typeck_results.node_substs_mut().remove(e.hir_id);
 169
 170                     match e.kind {
 171                         hir::ExprKind::Binary(..) => {
 172                             if !op.node.is_by_value() {
 173                                 let mut adjustments = typeck_results.adjustments_mut();
 174                                 if let Some(a) = adjustments.get_mut(lhs.hir_id) {
 175                                     a.pop();
 176                                 }
 177                                 if let Some(a) = adjustments.get_mut(rhs.hir_id) {
 178                                     a.pop();
 179                                 }
 180                             }
 181                         }
 182                         hir::ExprKind::AssignOp(..)
 183                             if let Some(a) = typeck_results.adjustments_mut().get_mut(lhs.hir_id) =>
 184                         {
 185                             a.pop();
 186                         }
 187                         _ => {}
 188                     }
 189                 }
 190             }
 191             _ => {}
 192         }
 193     }
 194
 195     // Similar to operators, indexing is always assumed to be overloaded
 196     // Here, correct cases where an indexing expression can be simplified
 197     // to use builtin indexing because the index type is known to be
 198     // usize-ish
 199     fn fix_index_builtin_expr(&mut self, e: &hir::Expr<'_>) {
 200         if let hir::ExprKind::Index(ref base, ref index) = e.kind {
 201             let mut typeck_results = self.fcx.typeck_results.borrow_mut();
 202
 203             // All valid indexing looks like this; might encounter non-valid indexes at this point.
 204             let base_ty = typeck_results
 205                 .expr_ty_adjusted_opt(base)
 206                 .map(|t| self.fcx.resolve_vars_if_possible(t).kind());
 207             if base_ty.is_none() {
 208                 // When encountering `return [0][0]` outside of a `fn` body we can encounter a base
 209                 // that isn't in the type table. We assume more relevant errors have already been
 210                 // emitted, so we delay an ICE if none have. (#64638)
 211                 self.tcx().sess.delay_span_bug(e.span, &format!("bad base: `{:?}`", base));
 212             }
 213             if let Some(ty::Ref(_, base_ty, _)) = base_ty {
 214                 let index_ty = typeck_results.expr_ty_adjusted_opt(index).unwrap_or_else(|| {
 215                     // When encountering `return [0][0]` outside of a `fn` body we would attempt
 216                     // to access an nonexistent index. We assume that more relevant errors will
 217                     // already have been emitted, so we only gate on this with an ICE if no
 218                     // error has been emitted. (#64638)
 219                     self.fcx.tcx.ty_error_with_message(
 220                         e.span,
 221                         &format!("bad index {:?} for base: `{:?}`", index, base),
 222                     )
 223                 });
 224                 let index_ty = self.fcx.resolve_vars_if_possible(index_ty);
 225
 226                 if base_ty.builtin_index().is_some() && index_ty == self.fcx.tcx.types.usize {
 227                     // Remove the method call record
 228                     typeck_results.type_dependent_defs_mut().remove(e.hir_id);
 229                     typeck_results.node_substs_mut().remove(e.hir_id);
 230
 231                     if let Some(a) = typeck_results.adjustments_mut().get_mut(base.hir_id) {
 232                         // Discard the need for a mutable borrow
 233
 234                         // Extra adjustment made when indexing causes a drop
 235                         // of size information - we need to get rid of it
 236                         // Since this is "after" the other adjustment to be
 237                         // discarded, we do an extra `pop()`
 238                         if let Some(Adjustment {
 239                             kind: Adjust::Pointer(PointerCast::Unsize), ..
 240                         }) = a.pop()
 241                         {
 242                             // So the borrow discard actually happens here
 243                             a.pop();
 244                         }
 245                     }
 246                 }
 247             }
 248         }
 249     }
 250 }
 251
 252 ///////////////////////////////////////////////////////////////////////////
 253 // Impl of Visitor for Resolver
 254 //
 255 // This is the master code which walks the AST. It delegates most of
 256 // the heavy lifting to the generic visit and resolve functions
 257 // below. In general, a function is made into a `visitor` if it must
 258 // traffic in node-ids or update typeck results in the type context etc.
 259
 260 impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
 261     fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
 262         self.fix_scalar_builtin_expr(e);
 263         self.fix_index_builtin_expr(e);
 264
 265         match e.kind {
 266             hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
 267                 let body = self.fcx.tcx.hir().body(body);
 268                 for param in body.params {
 269                     self.visit_node_id(e.span, param.hir_id);
 270                 }
 271
 272                 self.visit_body(body);
 273             }
 274             hir::ExprKind::Struct(_, fields, _) => {
 275                 for field in fields {
 276                     self.visit_field_id(field.hir_id);
 277                 }
 278             }
 279             hir::ExprKind::Field(..) => {
 280                 self.visit_field_id(e.hir_id);
 281             }
 282             hir::ExprKind::ConstBlock(anon_const) => {
 283                 self.visit_node_id(e.span, anon_const.hir_id);
 284
 285                 let body = self.tcx().hir().body(anon_const.body);
 286                 self.visit_body(body);
 287             }
 288             _ => {}
 289         }
 290
 291         self.visit_node_id(e.span, e.hir_id);
 292         intravisit::walk_expr(self, e);
 293     }
 294
 295     fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
 296         match &p.kind {
 297             hir::GenericParamKind::Lifetime { .. } => {
 298                 // Nothing to write back here
 299             }
 300             hir::GenericParamKind::Type { .. } | hir::GenericParamKind::Const { .. } => {
 301                 self.tcx().sess.delay_span_bug(p.span, format!("unexpected generic param: {p:?}"));
 302             }
 303         }
 304     }
 305
 306     fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
 307         self.visit_node_id(b.span, b.hir_id);
 308         intravisit::walk_block(self, b);
 309     }
 310
 311     fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
 312         match p.kind {
 313             hir::PatKind::Binding(..) => {
 314                 let typeck_results = self.fcx.typeck_results.borrow();
 315                 if let Some(bm) =
 316                     typeck_results.extract_binding_mode(self.tcx().sess, p.hir_id, p.span)
 317                 {
 318                     self.typeck_results.pat_binding_modes_mut().insert(p.hir_id, bm);
 319                 }
 320             }
 321             hir::PatKind::Struct(_, fields, _) => {
 322                 for field in fields {
 323                     self.visit_field_id(field.hir_id);
 324                 }
 325             }
 326             _ => {}
 327         };
 328
 329         self.visit_pat_adjustments(p.span, p.hir_id);
 330
 331         self.visit_node_id(p.span, p.hir_id);
 332         intravisit::walk_pat(self, p);
 333     }
 334
 335     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
 336         intravisit::walk_local(self, l);
 337         let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
 338         let var_ty = self.resolve(var_ty, &l.span);
 339         self.write_ty_to_typeck_results(l.hir_id, var_ty);
 340     }
 341
 342     fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx>) {
 343         intravisit::walk_ty(self, hir_ty);
 344         let ty = self.fcx.node_ty(hir_ty.hir_id);
 345         let ty = self.resolve(ty, &hir_ty.span);
 346         self.write_ty_to_typeck_results(hir_ty.hir_id, ty);
 347     }
 348
 349     fn visit_infer(&mut self, inf: &'tcx hir::InferArg) {
 350         intravisit::walk_inf(self, inf);
 351         // Ignore cases where the inference is a const.
 352         if let Some(ty) = self.fcx.node_ty_opt(inf.hir_id) {
 353             let ty = self.resolve(ty, &inf.span);
 354             self.write_ty_to_typeck_results(inf.hir_id, ty);
 355         }
 356     }
 357 }
 358
 359 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
 360     fn eval_closure_size(&mut self) {
 361         let mut res: FxHashMap<LocalDefId, ClosureSizeProfileData<'tcx>> = Default::default();
 362         for (&closure_def_id, data) in self.fcx.typeck_results.borrow().closure_size_eval.iter() {
 363             let closure_hir_id = self.tcx().hir().local_def_id_to_hir_id(closure_def_id);
 364
 365             let data = self.resolve(*data, &closure_hir_id);
 366
 367             res.insert(closure_def_id, data);
 368         }
 369
 370         self.typeck_results.closure_size_eval = res;
 371     }
 372     fn visit_min_capture_map(&mut self) {
 373         let mut min_captures_wb = ty::MinCaptureInformationMap::with_capacity_and_hasher(
 374             self.fcx.typeck_results.borrow().closure_min_captures.len(),
 375             Default::default(),
 376         );
 377         for (&closure_def_id, root_min_captures) in
 378             self.fcx.typeck_results.borrow().closure_min_captures.iter()
 379         {
 380             let mut root_var_map_wb = ty::RootVariableMinCaptureList::with_capacity_and_hasher(
 381                 root_min_captures.len(),
 382                 Default::default(),
 383             );
 384             for (var_hir_id, min_list) in root_min_captures.iter() {
 385                 let min_list_wb = min_list
 386                     .iter()
 387                     .map(|captured_place| {
 388                         let locatable = captured_place.info.path_expr_id.unwrap_or_else(|| {
 389                             self.tcx().hir().local_def_id_to_hir_id(closure_def_id)
 390                         });
 391
 392                         self.resolve(captured_place.clone(), &locatable)
 393                     })
 394                     .collect();
 395                 root_var_map_wb.insert(*var_hir_id, min_list_wb);
 396             }
 397             min_captures_wb.insert(closure_def_id, root_var_map_wb);
 398         }
 399
 400         self.typeck_results.closure_min_captures = min_captures_wb;
 401     }
 402
 403     fn visit_fake_reads_map(&mut self) {
 404         let mut resolved_closure_fake_reads: FxHashMap<
 405             LocalDefId,
 406             Vec<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>,
 407         > = Default::default();
 408         for (&closure_def_id, fake_reads) in
 409             self.fcx.typeck_results.borrow().closure_fake_reads.iter()
 410         {
 411             let mut resolved_fake_reads = Vec::<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>::new();
 412             for (place, cause, hir_id) in fake_reads.iter() {
 413                 let locatable = self.tcx().hir().local_def_id_to_hir_id(closure_def_id);
 414
 415                 let resolved_fake_read = self.resolve(place.clone(), &locatable);
 416                 resolved_fake_reads.push((resolved_fake_read, *cause, *hir_id));
 417             }
 418             resolved_closure_fake_reads.insert(closure_def_id, resolved_fake_reads);
 419         }
 420         self.typeck_results.closure_fake_reads = resolved_closure_fake_reads;
 421     }
 422
 423     fn visit_closures(&mut self) {
 424         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 425         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 426         let common_hir_owner = fcx_typeck_results.hir_owner;
 427
 428         for (id, origin) in fcx_typeck_results.closure_kind_origins().iter() {
 429             let hir_id = hir::HirId { owner: common_hir_owner, local_id: *id };
 430             let place_span = origin.0;
 431             let place = self.resolve(origin.1.clone(), &place_span);
 432             self.typeck_results.closure_kind_origins_mut().insert(hir_id, (place_span, place));
 433         }
 434     }
 435
 436     fn visit_coercion_casts(&mut self) {
 437         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 438         let fcx_coercion_casts = fcx_typeck_results.coercion_casts();
 439         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 440
 441         for local_id in fcx_coercion_casts {
 442             self.typeck_results.set_coercion_cast(*local_id);
 443         }
 444     }
 445
 446     fn visit_user_provided_tys(&mut self) {
 447         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 448         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 449         let common_hir_owner = fcx_typeck_results.hir_owner;
 450
 451         let mut errors_buffer = Vec::new();
 452         for (&local_id, c_ty) in fcx_typeck_results.user_provided_types().iter() {
 453             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 454
 455             if cfg!(debug_assertions) && c_ty.needs_infer() {
 456                 span_bug!(
 457                     hir_id.to_span(self.fcx.tcx),
 458                     "writeback: `{:?}` has inference variables",
 459                     c_ty
 460                 );
 461             };
 462
 463             self.typeck_results.user_provided_types_mut().insert(hir_id, *c_ty);
 464
 465             if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
 466                 if self.rustc_dump_user_substs {
 467                     // This is a unit-testing mechanism.
 468                     let span = self.tcx().hir().span(hir_id);
 469                     // We need to buffer the errors in order to guarantee a consistent
 470                     // order when emitting them.
 471                     let err = self
 472                         .tcx()
 473                         .sess
 474                         .struct_span_err(span, &format!("user substs: {:?}", user_substs));
 475                     err.buffer(&mut errors_buffer);
 476                 }
 477             }
 478         }
 479
 480         if !errors_buffer.is_empty() {
 481             errors_buffer.sort_by_key(|diag| diag.span.primary_span());
 482             for mut diag in errors_buffer.drain(..) {
 483                 self.tcx().sess.diagnostic().emit_diagnostic(&mut diag);
 484             }
 485         }
 486     }
 487
 488     fn visit_user_provided_sigs(&mut self) {
 489         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 490         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 491
 492         for (&def_id, c_sig) in fcx_typeck_results.user_provided_sigs.iter() {
 493             if cfg!(debug_assertions) && c_sig.needs_infer() {
 494                 span_bug!(
 495                     self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
 496                     "writeback: `{:?}` has inference variables",
 497                     c_sig
 498                 );
 499             };
 500
 501             self.typeck_results.user_provided_sigs.insert(def_id, *c_sig);
 502         }
 503     }
 504
 505     fn visit_generator_interior_types(&mut self) {
 506         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 507         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 508         self.typeck_results.generator_interior_types =
 509             fcx_typeck_results.generator_interior_types.clone();
 510     }
 511
 512     #[instrument(skip(self), level = "debug")]
 513     fn visit_opaque_types(&mut self) {
 514         let opaque_types =
 515             self.fcx.infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
 516         for (opaque_type_key, decl) in opaque_types {
 517             let hidden_type = match decl.origin {
 518                 hir::OpaqueTyOrigin::FnReturn(_) | hir::OpaqueTyOrigin::AsyncFn(_) => {
 519                     let ty = self.resolve(decl.hidden_type.ty, &decl.hidden_type.span);
 520                     struct RecursionChecker {
 521                         def_id: LocalDefId,
 522                     }
 523                     impl<'tcx> ty::TypeVisitor<'tcx> for RecursionChecker {
 524                         type BreakTy = ();
 525                         fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
 526                             if let ty::Opaque(def_id, _) = *t.kind() {
 527                                 if def_id == self.def_id.to_def_id() {
 528                                     return ControlFlow::Break(());
 529                                 }
 530                             }
 531                             t.super_visit_with(self)
 532                         }
 533                     }
 534                     if ty
 535                         .visit_with(&mut RecursionChecker { def_id: opaque_type_key.def_id })
 536                         .is_break()
 537                     {
 538                         return;
 539                     }
 540                     Some(ty)
 541                 }
 542                 hir::OpaqueTyOrigin::TyAlias => None,
 543             };
 544             self.typeck_results.concrete_opaque_types.insert(opaque_type_key.def_id, hidden_type);
 545         }
 546     }
 547
 548     fn visit_field_id(&mut self, hir_id: hir::HirId) {
 549         if let Some(index) = self.fcx.typeck_results.borrow_mut().field_indices_mut().remove(hir_id)
 550         {
 551             self.typeck_results.field_indices_mut().insert(hir_id, index);
 552         }
 553     }
 554
 555     #[instrument(skip(self, span), level = "debug")]
 556     fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
 557         // Export associated path extensions and method resolutions.
 558         if let Some(def) =
 559             self.fcx.typeck_results.borrow_mut().type_dependent_defs_mut().remove(hir_id)
 560         {
 561             self.typeck_results.type_dependent_defs_mut().insert(hir_id, def);
 562         }
 563
 564         // Resolve any borrowings for the node with id `node_id`
 565         self.visit_adjustments(span, hir_id);
 566
 567         // Resolve the type of the node with id `node_id`
 568         let n_ty = self.fcx.node_ty(hir_id);
 569         let n_ty = self.resolve(n_ty, &span);
 570         self.write_ty_to_typeck_results(hir_id, n_ty);
 571         debug!(?n_ty);
 572
 573         // Resolve any substitutions
 574         if let Some(substs) = self.fcx.typeck_results.borrow().node_substs_opt(hir_id) {
 575             let substs = self.resolve(substs, &span);
 576             debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
 577             assert!(!substs.needs_infer() && !substs.has_placeholders());
 578             self.typeck_results.node_substs_mut().insert(hir_id, substs);
 579         }
 580     }
 581
 582     #[instrument(skip(self, span), level = "debug")]
 583     fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 584         let adjustment = self.fcx.typeck_results.borrow_mut().adjustments_mut().remove(hir_id);
 585         match adjustment {
 586             None => {
 587                 debug!("no adjustments for node");
 588             }
 589
 590             Some(adjustment) => {
 591                 let resolved_adjustment = self.resolve(adjustment, &span);
 592                 debug!(?resolved_adjustment);
 593                 self.typeck_results.adjustments_mut().insert(hir_id, resolved_adjustment);
 594             }
 595         }
 596     }
 597
 598     #[instrument(skip(self, span), level = "debug")]
 599     fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 600         let adjustment = self.fcx.typeck_results.borrow_mut().pat_adjustments_mut().remove(hir_id);
 601         match adjustment {
 602             None => {
 603                 debug!("no pat_adjustments for node");
 604             }
 605
 606             Some(adjustment) => {
 607                 let resolved_adjustment = self.resolve(adjustment, &span);
 608                 debug!(?resolved_adjustment);
 609                 self.typeck_results.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
 610             }
 611         }
 612     }
 613
 614     fn visit_liberated_fn_sigs(&mut self) {
 615         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 616         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 617         let common_hir_owner = fcx_typeck_results.hir_owner;
 618
 619         for (&local_id, &fn_sig) in fcx_typeck_results.liberated_fn_sigs().iter() {
 620             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 621             let fn_sig = self.resolve(fn_sig, &hir_id);
 622             self.typeck_results.liberated_fn_sigs_mut().insert(hir_id, fn_sig);
 623         }
 624     }
 625
 626     fn visit_fru_field_types(&mut self) {
 627         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 628         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 629         let common_hir_owner = fcx_typeck_results.hir_owner;
 630
 631         for (&local_id, ftys) in fcx_typeck_results.fru_field_types().iter() {
 632             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 633             let ftys = self.resolve(ftys.clone(), &hir_id);
 634             self.typeck_results.fru_field_types_mut().insert(hir_id, ftys);
 635         }
 636     }
 637
 638     fn resolve<T>(&mut self, x: T, span: &dyn Locatable) -> T
 639     where
 640         T: TypeFoldable<'tcx>,
 641     {
 642         let mut resolver = Resolver::new(self.fcx, span, self.body);
 643         let x = x.fold_with(&mut resolver);
 644         if cfg!(debug_assertions) && x.needs_infer() {
 645             span_bug!(span.to_span(self.fcx.tcx), "writeback: `{:?}` has inference variables", x);
 646         }
 647
 648         // We may have introduced e.g. `ty::Error`, if inference failed, make sure
 649         // to mark the `TypeckResults` as tainted in that case, so that downstream
 650         // users of the typeck results don't produce extra errors, or worse, ICEs.
 651         if resolver.replaced_with_error {
 652             // FIXME(eddyb) keep track of `ErrorGuaranteed` from where the error was emitted.
 653             self.typeck_results.tainted_by_errors =
 654                 Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
 655         }
 656
 657         x
 658     }
 659 }
 660
 661 pub(crate) trait Locatable {
 662     fn to_span(&self, tcx: TyCtxt<'_>) -> Span;
 663 }
 664
 665 impl Locatable for Span {
 666     fn to_span(&self, _: TyCtxt<'_>) -> Span {
 667         *self
 668     }
 669 }
 670
 671 impl Locatable for hir::HirId {
 672     fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
 673         tcx.hir().span(*self)
 674     }
 675 }
 676
 677 /// The Resolver. This is the type folding engine that detects
 678 /// unresolved types and so forth.
 679 struct Resolver<'cx, 'tcx> {
 680     tcx: TyCtxt<'tcx>,
 681     infcx: &'cx InferCtxt<'cx, 'tcx>,
 682     span: &'cx dyn Locatable,
 683     body: &'tcx hir::Body<'tcx>,
 684
 685     /// Set to `true` if any `Ty` or `ty::Const` had to be replaced with an `Error`.
 686     replaced_with_error: bool,
 687 }
 688
 689 impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
 690     fn new(
 691         fcx: &'cx FnCtxt<'cx, 'tcx>,
 692         span: &'cx dyn Locatable,
 693         body: &'tcx hir::Body<'tcx>,
 694     ) -> Resolver<'cx, 'tcx> {
 695         Resolver { tcx: fcx.tcx, infcx: fcx, span, body, replaced_with_error: false }
 696     }
 697
 698     fn report_type_error(&self, t: Ty<'tcx>) {
 699         if !self.tcx.sess.has_errors().is_some() {
 700             self.infcx
 701                 .emit_inference_failure_err(
 702                     Some(self.body.id()),
 703                     self.span.to_span(self.tcx),
 704                     t.into(),
 705                     E0282,
 706                     false,
 707                 )
 708                 .emit();
 709         }
 710     }
 711
 712     fn report_const_error(&self, c: ty::Const<'tcx>) {
 713         if self.tcx.sess.has_errors().is_none() {
 714             self.infcx
 715                 .emit_inference_failure_err(
 716                     Some(self.body.id()),
 717                     self.span.to_span(self.tcx),
 718                     c.into(),
 719                     E0282,
 720                     false,
 721                 )
 722                 .emit();
 723         }
 724     }
 725 }
 726
 727 struct EraseEarlyRegions<'tcx> {
 728     tcx: TyCtxt<'tcx>,
 729 }
 730
 731 impl<'tcx> TypeFolder<'tcx> for EraseEarlyRegions<'tcx> {
 732     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
 733         self.tcx
 734     }
 735     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
 736         if ty.has_type_flags(ty::TypeFlags::HAS_FREE_REGIONS) {
 737             ty.super_fold_with(self)
 738         } else {
 739             ty
 740         }
 741     }
 742     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
 743         if r.is_late_bound() { r } else { self.tcx.lifetimes.re_erased }
 744     }
 745 }
 746
 747 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
 748     fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
 749         self.tcx
 750     }
 751
 752     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
 753         match self.infcx.fully_resolve(t) {
 754             Ok(t) => {
 755                 // Do not anonymize late-bound regions
 756                 // (e.g. keep `for<'a>` named `for<'a>`).
 757                 // This allows NLL to generate error messages that
 758                 // refer to the higher-ranked lifetime names written by the user.
 759                 EraseEarlyRegions { tcx: self.tcx }.fold_ty(t)
 760             }
 761             Err(_) => {
 762                 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable", t);
 763                 self.report_type_error(t);
 764                 self.replaced_with_error = true;
 765                 self.tcx().ty_error()
 766             }
 767         }
 768     }
 769
 770     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
 771         debug_assert!(!r.is_late_bound(), "Should not be resolving bound region.");
 772         self.tcx.lifetimes.re_erased
 773     }
 774
 775     fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
 776         match self.infcx.fully_resolve(ct) {
 777             Ok(ct) => self.tcx.erase_regions(ct),
 778             Err(_) => {
 779                 debug!("Resolver::fold_const: input const `{:?}` not fully resolvable", ct);
 780                 self.report_const_error(ct);
 781                 self.replaced_with_error = true;
 782                 self.tcx().const_error(ct.ty())
 783             }
 784         }
 785     }
 786 }
 787
 788 ///////////////////////////////////////////////////////////////////////////
 789 // During type check, we store promises with the result of trait
 790 // lookup rather than the actual results (because the results are not
 791 // necessarily available immediately). These routines unwind the
 792 // promises. It is expected that we will have already reported any
 793 // errors that may be encountered, so if the promises store an error,
 794 // a dummy result is returned.