compiler/rustc_hir_typeck/src/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::FnCtxt;
   6 use hir::def_id::LocalDefId;
   7 use rustc_data_structures::fx::FxHashMap;
   8 use rustc_errors::ErrorGuaranteed;
   9 use rustc_hir as hir;
  10 use rustc_hir::intravisit::{self, Visitor};
  11 use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
  12 use rustc_infer::infer::InferCtxt;
  13 use rustc_middle::hir::place::Place as HirPlace;
  14 use rustc_middle::mir::FakeReadCause;
  15 use rustc_middle::ty::adjustment::{Adjust, Adjustment, PointerCast};
  16 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
  17 use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable};
  18 use rustc_middle::ty::TypeckResults;
  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     // (ouz-a 1005988): Normally `[T] : std::ops::Index<usize>` should be normalized
 196     // into [T] but currently `Where` clause stops the normalization process for it,
 197     // here we compare types of expr and base in a code without `Where` clause they would be equal
 198     // if they are not we don't modify the expr, hence we bypass the ICE
 199     fn is_builtin_index(
 200         &mut self,
 201         typeck_results: &TypeckResults<'tcx>,
 202         e: &hir::Expr<'_>,
 203         base_ty: Ty<'tcx>,
 204         index_ty: Ty<'tcx>,
 205     ) -> bool {
 206         if let Some(elem_ty) = base_ty.builtin_index() {
 207             let Some(exp_ty) = typeck_results.expr_ty_opt(e) else {return false;};
 208             let resolved_exp_ty = self.resolve(exp_ty, &e.span);
 209
 210             elem_ty == resolved_exp_ty && index_ty == self.fcx.tcx.types.usize
 211         } else {
 212             false
 213         }
 214     }
 215
 216     // Similar to operators, indexing is always assumed to be overloaded
 217     // Here, correct cases where an indexing expression can be simplified
 218     // to use builtin indexing because the index type is known to be
 219     // usize-ish
 220     fn fix_index_builtin_expr(&mut self, e: &hir::Expr<'_>) {
 221         if let hir::ExprKind::Index(ref base, ref index) = e.kind {
 222             let mut typeck_results = self.fcx.typeck_results.borrow_mut();
 223
 224             // All valid indexing looks like this; might encounter non-valid indexes at this point.
 225             let base_ty = typeck_results
 226                 .expr_ty_adjusted_opt(base)
 227                 .map(|t| self.fcx.resolve_vars_if_possible(t).kind());
 228             if base_ty.is_none() {
 229                 // When encountering `return [0][0]` outside of a `fn` body we can encounter a base
 230                 // that isn't in the type table. We assume more relevant errors have already been
 231                 // emitted, so we delay an ICE if none have. (#64638)
 232                 self.tcx().sess.delay_span_bug(e.span, &format!("bad base: `{:?}`", base));
 233             }
 234             if let Some(ty::Ref(_, base_ty, _)) = base_ty {
 235                 let index_ty = typeck_results.expr_ty_adjusted_opt(index).unwrap_or_else(|| {
 236                     // When encountering `return [0][0]` outside of a `fn` body we would attempt
 237                     // to access an nonexistent index. We assume that more relevant errors will
 238                     // already have been emitted, so we only gate on this with an ICE if no
 239                     // error has been emitted. (#64638)
 240                     self.fcx.tcx.ty_error_with_message(
 241                         e.span,
 242                         &format!("bad index {:?} for base: `{:?}`", index, base),
 243                     )
 244                 });
 245                 let index_ty = self.fcx.resolve_vars_if_possible(index_ty);
 246                 let resolved_base_ty = self.resolve(*base_ty, &base.span);
 247
 248                 if self.is_builtin_index(&typeck_results, e, resolved_base_ty, index_ty) {
 249                     // Remove the method call record
 250                     typeck_results.type_dependent_defs_mut().remove(e.hir_id);
 251                     typeck_results.node_substs_mut().remove(e.hir_id);
 252
 253                     if let Some(a) = typeck_results.adjustments_mut().get_mut(base.hir_id) {
 254                         // Discard the need for a mutable borrow
 255
 256                         // Extra adjustment made when indexing causes a drop
 257                         // of size information - we need to get rid of it
 258                         // Since this is "after" the other adjustment to be
 259                         // discarded, we do an extra `pop()`
 260                         if let Some(Adjustment {
 261                             kind: Adjust::Pointer(PointerCast::Unsize), ..
 262                         }) = a.pop()
 263                         {
 264                             // So the borrow discard actually happens here
 265                             a.pop();
 266                         }
 267                     }
 268                 }
 269             }
 270         }
 271     }
 272 }
 273
 274 ///////////////////////////////////////////////////////////////////////////
 275 // Impl of Visitor for Resolver
 276 //
 277 // This is the master code which walks the AST. It delegates most of
 278 // the heavy lifting to the generic visit and resolve functions
 279 // below. In general, a function is made into a `visitor` if it must
 280 // traffic in node-ids or update typeck results in the type context etc.
 281
 282 impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
 283     fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
 284         self.fix_scalar_builtin_expr(e);
 285         self.fix_index_builtin_expr(e);
 286
 287         match e.kind {
 288             hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
 289                 let body = self.fcx.tcx.hir().body(body);
 290                 for param in body.params {
 291                     self.visit_node_id(e.span, param.hir_id);
 292                 }
 293
 294                 self.visit_body(body);
 295             }
 296             hir::ExprKind::Struct(_, fields, _) => {
 297                 for field in fields {
 298                     self.visit_field_id(field.hir_id);
 299                 }
 300             }
 301             hir::ExprKind::Field(..) => {
 302                 self.visit_field_id(e.hir_id);
 303             }
 304             hir::ExprKind::ConstBlock(anon_const) => {
 305                 self.visit_node_id(e.span, anon_const.hir_id);
 306
 307                 let body = self.tcx().hir().body(anon_const.body);
 308                 self.visit_body(body);
 309             }
 310             _ => {}
 311         }
 312
 313         self.visit_node_id(e.span, e.hir_id);
 314         intravisit::walk_expr(self, e);
 315     }
 316
 317     fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
 318         match &p.kind {
 319             hir::GenericParamKind::Lifetime { .. } => {
 320                 // Nothing to write back here
 321             }
 322             hir::GenericParamKind::Type { .. } | hir::GenericParamKind::Const { .. } => {
 323                 self.tcx().sess.delay_span_bug(p.span, format!("unexpected generic param: {p:?}"));
 324             }
 325         }
 326     }
 327
 328     fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
 329         self.visit_node_id(b.span, b.hir_id);
 330         intravisit::walk_block(self, b);
 331     }
 332
 333     fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
 334         match p.kind {
 335             hir::PatKind::Binding(..) => {
 336                 let typeck_results = self.fcx.typeck_results.borrow();
 337                 if let Some(bm) =
 338                     typeck_results.extract_binding_mode(self.tcx().sess, p.hir_id, p.span)
 339                 {
 340                     self.typeck_results.pat_binding_modes_mut().insert(p.hir_id, bm);
 341                 }
 342             }
 343             hir::PatKind::Struct(_, fields, _) => {
 344                 for field in fields {
 345                     self.visit_field_id(field.hir_id);
 346                 }
 347             }
 348             _ => {}
 349         };
 350
 351         self.visit_pat_adjustments(p.span, p.hir_id);
 352
 353         self.visit_node_id(p.span, p.hir_id);
 354         intravisit::walk_pat(self, p);
 355     }
 356
 357     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
 358         intravisit::walk_local(self, l);
 359         let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
 360         let var_ty = self.resolve(var_ty, &l.span);
 361         self.write_ty_to_typeck_results(l.hir_id, var_ty);
 362     }
 363
 364     fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx>) {
 365         intravisit::walk_ty(self, hir_ty);
 366         // If there are type checking errors, Type privacy pass will stop,
 367         // so we may not get the type from hid_id, see #104513
 368         if let Some(ty) = self.fcx.node_ty_opt(hir_ty.hir_id) {
 369             let ty = self.resolve(ty, &hir_ty.span);
 370             self.write_ty_to_typeck_results(hir_ty.hir_id, ty);
 371         }
 372     }
 373
 374     fn visit_infer(&mut self, inf: &'tcx hir::InferArg) {
 375         intravisit::walk_inf(self, inf);
 376         // Ignore cases where the inference is a const.
 377         if let Some(ty) = self.fcx.node_ty_opt(inf.hir_id) {
 378             let ty = self.resolve(ty, &inf.span);
 379             self.write_ty_to_typeck_results(inf.hir_id, ty);
 380         }
 381     }
 382 }
 383
 384 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
 385     fn eval_closure_size(&mut self) {
 386         let mut res: FxHashMap<LocalDefId, ClosureSizeProfileData<'tcx>> = Default::default();
 387         for (&closure_def_id, data) in self.fcx.typeck_results.borrow().closure_size_eval.iter() {
 388             let closure_hir_id = self.tcx().hir().local_def_id_to_hir_id(closure_def_id);
 389
 390             let data = self.resolve(*data, &closure_hir_id);
 391
 392             res.insert(closure_def_id, data);
 393         }
 394
 395         self.typeck_results.closure_size_eval = res;
 396     }
 397     fn visit_min_capture_map(&mut self) {
 398         let mut min_captures_wb = ty::MinCaptureInformationMap::with_capacity_and_hasher(
 399             self.fcx.typeck_results.borrow().closure_min_captures.len(),
 400             Default::default(),
 401         );
 402         for (&closure_def_id, root_min_captures) in
 403             self.fcx.typeck_results.borrow().closure_min_captures.iter()
 404         {
 405             let mut root_var_map_wb = ty::RootVariableMinCaptureList::with_capacity_and_hasher(
 406                 root_min_captures.len(),
 407                 Default::default(),
 408             );
 409             for (var_hir_id, min_list) in root_min_captures.iter() {
 410                 let min_list_wb = min_list
 411                     .iter()
 412                     .map(|captured_place| {
 413                         let locatable = captured_place.info.path_expr_id.unwrap_or_else(|| {
 414                             self.tcx().hir().local_def_id_to_hir_id(closure_def_id)
 415                         });
 416
 417                         self.resolve(captured_place.clone(), &locatable)
 418                     })
 419                     .collect();
 420                 root_var_map_wb.insert(*var_hir_id, min_list_wb);
 421             }
 422             min_captures_wb.insert(closure_def_id, root_var_map_wb);
 423         }
 424
 425         self.typeck_results.closure_min_captures = min_captures_wb;
 426     }
 427
 428     fn visit_fake_reads_map(&mut self) {
 429         let mut resolved_closure_fake_reads: FxHashMap<
 430             LocalDefId,
 431             Vec<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>,
 432         > = Default::default();
 433         for (&closure_def_id, fake_reads) in
 434             self.fcx.typeck_results.borrow().closure_fake_reads.iter()
 435         {
 436             let mut resolved_fake_reads = Vec::<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>::new();
 437             for (place, cause, hir_id) in fake_reads.iter() {
 438                 let locatable = self.tcx().hir().local_def_id_to_hir_id(closure_def_id);
 439
 440                 let resolved_fake_read = self.resolve(place.clone(), &locatable);
 441                 resolved_fake_reads.push((resolved_fake_read, *cause, *hir_id));
 442             }
 443             resolved_closure_fake_reads.insert(closure_def_id, resolved_fake_reads);
 444         }
 445         self.typeck_results.closure_fake_reads = resolved_closure_fake_reads;
 446     }
 447
 448     fn visit_closures(&mut self) {
 449         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 450         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 451         let common_hir_owner = fcx_typeck_results.hir_owner;
 452
 453         for (id, origin) in fcx_typeck_results.closure_kind_origins().iter() {
 454             let hir_id = hir::HirId { owner: common_hir_owner, local_id: *id };
 455             let place_span = origin.0;
 456             let place = self.resolve(origin.1.clone(), &place_span);
 457             self.typeck_results.closure_kind_origins_mut().insert(hir_id, (place_span, place));
 458         }
 459     }
 460
 461     fn visit_coercion_casts(&mut self) {
 462         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 463         let fcx_coercion_casts = fcx_typeck_results.coercion_casts();
 464         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 465
 466         for local_id in fcx_coercion_casts {
 467             self.typeck_results.set_coercion_cast(*local_id);
 468         }
 469     }
 470
 471     fn visit_user_provided_tys(&mut self) {
 472         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 473         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 474         let common_hir_owner = fcx_typeck_results.hir_owner;
 475
 476         let mut errors_buffer = Vec::new();
 477         for (&local_id, c_ty) in fcx_typeck_results.user_provided_types().iter() {
 478             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 479
 480             if cfg!(debug_assertions) && c_ty.needs_infer() {
 481                 span_bug!(
 482                     hir_id.to_span(self.fcx.tcx),
 483                     "writeback: `{:?}` has inference variables",
 484                     c_ty
 485                 );
 486             };
 487
 488             self.typeck_results.user_provided_types_mut().insert(hir_id, *c_ty);
 489
 490             if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
 491                 if self.rustc_dump_user_substs {
 492                     // This is a unit-testing mechanism.
 493                     let span = self.tcx().hir().span(hir_id);
 494                     // We need to buffer the errors in order to guarantee a consistent
 495                     // order when emitting them.
 496                     let err = self
 497                         .tcx()
 498                         .sess
 499                         .struct_span_err(span, &format!("user substs: {:?}", user_substs));
 500                     err.buffer(&mut errors_buffer);
 501                 }
 502             }
 503         }
 504
 505         if !errors_buffer.is_empty() {
 506             errors_buffer.sort_by_key(|diag| diag.span.primary_span());
 507             for mut diag in errors_buffer {
 508                 self.tcx().sess.diagnostic().emit_diagnostic(&mut diag);
 509             }
 510         }
 511     }
 512
 513     fn visit_user_provided_sigs(&mut self) {
 514         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 515         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 516
 517         for (&def_id, c_sig) in fcx_typeck_results.user_provided_sigs.iter() {
 518             if cfg!(debug_assertions) && c_sig.needs_infer() {
 519                 span_bug!(
 520                     self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
 521                     "writeback: `{:?}` has inference variables",
 522                     c_sig
 523                 );
 524             };
 525
 526             self.typeck_results.user_provided_sigs.insert(def_id, *c_sig);
 527         }
 528     }
 529
 530     fn visit_generator_interior_types(&mut self) {
 531         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 532         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 533         self.typeck_results.generator_interior_types =
 534             fcx_typeck_results.generator_interior_types.clone();
 535     }
 536
 537     #[instrument(skip(self), level = "debug")]
 538     fn visit_opaque_types(&mut self) {
 539         let opaque_types =
 540             self.fcx.infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
 541         for (opaque_type_key, decl) in opaque_types {
 542             let hidden_type = self.resolve(decl.hidden_type, &decl.hidden_type.span);
 543             let opaque_type_key = self.resolve(opaque_type_key, &decl.hidden_type.span);
 544
 545             struct RecursionChecker {
 546                 def_id: LocalDefId,
 547             }
 548             impl<'tcx> ty::TypeVisitor<'tcx> for RecursionChecker {
 549                 type BreakTy = ();
 550                 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
 551                     if let ty::Opaque(def_id, _) = *t.kind() {
 552                         if def_id == self.def_id.to_def_id() {
 553                             return ControlFlow::Break(());
 554                         }
 555                     }
 556                     t.super_visit_with(self)
 557                 }
 558             }
 559             if hidden_type
 560                 .visit_with(&mut RecursionChecker { def_id: opaque_type_key.def_id })
 561                 .is_break()
 562             {
 563                 continue;
 564             }
 565
 566             let hidden_type = hidden_type.remap_generic_params_to_declaration_params(
 567                 opaque_type_key,
 568                 self.fcx.infcx.tcx,
 569                 true,
 570                 decl.origin,
 571             );
 572
 573             self.typeck_results.concrete_opaque_types.insert(opaque_type_key.def_id, hidden_type);
 574         }
 575     }
 576
 577     fn visit_field_id(&mut self, hir_id: hir::HirId) {
 578         if let Some(index) = self.fcx.typeck_results.borrow_mut().field_indices_mut().remove(hir_id)
 579         {
 580             self.typeck_results.field_indices_mut().insert(hir_id, index);
 581         }
 582     }
 583
 584     #[instrument(skip(self, span), level = "debug")]
 585     fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
 586         // Export associated path extensions and method resolutions.
 587         if let Some(def) =
 588             self.fcx.typeck_results.borrow_mut().type_dependent_defs_mut().remove(hir_id)
 589         {
 590             self.typeck_results.type_dependent_defs_mut().insert(hir_id, def);
 591         }
 592
 593         // Resolve any borrowings for the node with id `node_id`
 594         self.visit_adjustments(span, hir_id);
 595
 596         // Resolve the type of the node with id `node_id`
 597         let n_ty = self.fcx.node_ty(hir_id);
 598         let n_ty = self.resolve(n_ty, &span);
 599         self.write_ty_to_typeck_results(hir_id, n_ty);
 600         debug!(?n_ty);
 601
 602         // Resolve any substitutions
 603         if let Some(substs) = self.fcx.typeck_results.borrow().node_substs_opt(hir_id) {
 604             let substs = self.resolve(substs, &span);
 605             debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
 606             assert!(!substs.needs_infer() && !substs.has_placeholders());
 607             self.typeck_results.node_substs_mut().insert(hir_id, substs);
 608         }
 609     }
 610
 611     #[instrument(skip(self, span), level = "debug")]
 612     fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 613         let adjustment = self.fcx.typeck_results.borrow_mut().adjustments_mut().remove(hir_id);
 614         match adjustment {
 615             None => {
 616                 debug!("no adjustments for node");
 617             }
 618
 619             Some(adjustment) => {
 620                 let resolved_adjustment = self.resolve(adjustment, &span);
 621                 debug!(?resolved_adjustment);
 622                 self.typeck_results.adjustments_mut().insert(hir_id, resolved_adjustment);
 623             }
 624         }
 625     }
 626
 627     #[instrument(skip(self, span), level = "debug")]
 628     fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 629         let adjustment = self.fcx.typeck_results.borrow_mut().pat_adjustments_mut().remove(hir_id);
 630         match adjustment {
 631             None => {
 632                 debug!("no pat_adjustments for node");
 633             }
 634
 635             Some(adjustment) => {
 636                 let resolved_adjustment = self.resolve(adjustment, &span);
 637                 debug!(?resolved_adjustment);
 638                 self.typeck_results.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
 639             }
 640         }
 641     }
 642
 643     fn visit_liberated_fn_sigs(&mut self) {
 644         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 645         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 646         let common_hir_owner = fcx_typeck_results.hir_owner;
 647
 648         for (&local_id, &fn_sig) in fcx_typeck_results.liberated_fn_sigs().iter() {
 649             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 650             let fn_sig = self.resolve(fn_sig, &hir_id);
 651             self.typeck_results.liberated_fn_sigs_mut().insert(hir_id, fn_sig);
 652         }
 653     }
 654
 655     fn visit_fru_field_types(&mut self) {
 656         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 657         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 658         let common_hir_owner = fcx_typeck_results.hir_owner;
 659
 660         for (&local_id, ftys) in fcx_typeck_results.fru_field_types().iter() {
 661             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 662             let ftys = self.resolve(ftys.clone(), &hir_id);
 663             self.typeck_results.fru_field_types_mut().insert(hir_id, ftys);
 664         }
 665     }
 666
 667     fn resolve<T>(&mut self, x: T, span: &dyn Locatable) -> T
 668     where
 669         T: TypeFoldable<'tcx>,
 670     {
 671         let mut resolver = Resolver::new(self.fcx, span, self.body);
 672         let x = x.fold_with(&mut resolver);
 673         if cfg!(debug_assertions) && x.needs_infer() {
 674             span_bug!(span.to_span(self.fcx.tcx), "writeback: `{:?}` has inference variables", x);
 675         }
 676
 677         // We may have introduced e.g. `ty::Error`, if inference failed, make sure
 678         // to mark the `TypeckResults` as tainted in that case, so that downstream
 679         // users of the typeck results don't produce extra errors, or worse, ICEs.
 680         if resolver.replaced_with_error {
 681             // FIXME(eddyb) keep track of `ErrorGuaranteed` from where the error was emitted.
 682             self.typeck_results.tainted_by_errors =
 683                 Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
 684         }
 685
 686         x
 687     }
 688 }
 689
 690 pub(crate) trait Locatable {
 691     fn to_span(&self, tcx: TyCtxt<'_>) -> Span;
 692 }
 693
 694 impl Locatable for Span {
 695     fn to_span(&self, _: TyCtxt<'_>) -> Span {
 696         *self
 697     }
 698 }
 699
 700 impl Locatable for hir::HirId {
 701     fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
 702         tcx.hir().span(*self)
 703     }
 704 }
 705
 706 /// The Resolver. This is the type folding engine that detects
 707 /// unresolved types and so forth.
 708 struct Resolver<'cx, 'tcx> {
 709     tcx: TyCtxt<'tcx>,
 710     infcx: &'cx InferCtxt<'tcx>,
 711     span: &'cx dyn Locatable,
 712     body: &'tcx hir::Body<'tcx>,
 713
 714     /// Set to `true` if any `Ty` or `ty::Const` had to be replaced with an `Error`.
 715     replaced_with_error: bool,
 716 }
 717
 718 impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
 719     fn new(
 720         fcx: &'cx FnCtxt<'cx, 'tcx>,
 721         span: &'cx dyn Locatable,
 722         body: &'tcx hir::Body<'tcx>,
 723     ) -> Resolver<'cx, 'tcx> {
 724         Resolver { tcx: fcx.tcx, infcx: fcx, span, body, replaced_with_error: false }
 725     }
 726
 727     fn report_error(&self, p: impl Into<ty::GenericArg<'tcx>>) {
 728         if !self.tcx.sess.has_errors().is_some() {
 729             self.infcx
 730                 .err_ctxt()
 731                 .emit_inference_failure_err(
 732                     Some(self.body.id()),
 733                     self.span.to_span(self.tcx),
 734                     p.into(),
 735                     E0282,
 736                     false,
 737                 )
 738                 .emit();
 739         }
 740     }
 741 }
 742
 743 struct EraseEarlyRegions<'tcx> {
 744     tcx: TyCtxt<'tcx>,
 745 }
 746
 747 impl<'tcx> TypeFolder<'tcx> for EraseEarlyRegions<'tcx> {
 748     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
 749         self.tcx
 750     }
 751     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
 752         if ty.has_type_flags(ty::TypeFlags::HAS_FREE_REGIONS) {
 753             ty.super_fold_with(self)
 754         } else {
 755             ty
 756         }
 757     }
 758     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
 759         if r.is_late_bound() { r } else { self.tcx.lifetimes.re_erased }
 760     }
 761 }
 762
 763 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
 764     fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
 765         self.tcx
 766     }
 767
 768     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
 769         match self.infcx.fully_resolve(t) {
 770             Ok(t) => {
 771                 // Do not anonymize late-bound regions
 772                 // (e.g. keep `for<'a>` named `for<'a>`).
 773                 // This allows NLL to generate error messages that
 774                 // refer to the higher-ranked lifetime names written by the user.
 775                 EraseEarlyRegions { tcx: self.tcx }.fold_ty(t)
 776             }
 777             Err(_) => {
 778                 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable", t);
 779                 self.report_error(t);
 780                 self.replaced_with_error = true;
 781                 self.tcx().ty_error()
 782             }
 783         }
 784     }
 785
 786     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
 787         debug_assert!(!r.is_late_bound(), "Should not be resolving bound region.");
 788         self.tcx.lifetimes.re_erased
 789     }
 790
 791     fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
 792         match self.infcx.fully_resolve(ct) {
 793             Ok(ct) => self.tcx.erase_regions(ct),
 794             Err(_) => {
 795                 debug!("Resolver::fold_const: input const `{:?}` not fully resolvable", ct);
 796                 self.report_error(ct);
 797                 self.replaced_with_error = true;
 798                 self.tcx().const_error(ct.ty())
 799             }
 800         }
 801     }
 802 }
 803
 804 ///////////////////////////////////////////////////////////////////////////
 805 // During type check, we store promises with the result of trait
 806 // lookup rather than the actual results (because the results are not
 807 // necessarily available immediately). These routines unwind the
 808 // promises. It is expected that we will have already reported any
 809 // errors that may be encountered, so if the promises store an error,
 810 // a dummy result is returned.