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 rustc_data_structures::stable_map::FxHashMap;
   8 use rustc_errors::ErrorGuaranteed;
   9 use rustc_hir as hir;
  10 use rustc_hir::def_id::DefId;
  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_block(&mut self, b: &'tcx hir::Block<'tcx>) {
 296         self.visit_node_id(b.span, b.hir_id);
 297         intravisit::walk_block(self, b);
 298     }
 299
 300     fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
 301         match p.kind {
 302             hir::PatKind::Binding(..) => {
 303                 let typeck_results = self.fcx.typeck_results.borrow();
 304                 if let Some(bm) =
 305                     typeck_results.extract_binding_mode(self.tcx().sess, p.hir_id, p.span)
 306                 {
 307                     self.typeck_results.pat_binding_modes_mut().insert(p.hir_id, bm);
 308                 }
 309             }
 310             hir::PatKind::Struct(_, fields, _) => {
 311                 for field in fields {
 312                     self.visit_field_id(field.hir_id);
 313                 }
 314             }
 315             _ => {}
 316         };
 317
 318         self.visit_pat_adjustments(p.span, p.hir_id);
 319
 320         self.visit_node_id(p.span, p.hir_id);
 321         intravisit::walk_pat(self, p);
 322     }
 323
 324     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
 325         intravisit::walk_local(self, l);
 326         let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
 327         let var_ty = self.resolve(var_ty, &l.span);
 328         self.write_ty_to_typeck_results(l.hir_id, var_ty);
 329     }
 330
 331     fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx>) {
 332         intravisit::walk_ty(self, hir_ty);
 333         let ty = self.fcx.node_ty(hir_ty.hir_id);
 334         let ty = self.resolve(ty, &hir_ty.span);
 335         self.write_ty_to_typeck_results(hir_ty.hir_id, ty);
 336     }
 337
 338     fn visit_infer(&mut self, inf: &'tcx hir::InferArg) {
 339         intravisit::walk_inf(self, inf);
 340         // Ignore cases where the inference is a const.
 341         if let Some(ty) = self.fcx.node_ty_opt(inf.hir_id) {
 342             let ty = self.resolve(ty, &inf.span);
 343             self.write_ty_to_typeck_results(inf.hir_id, ty);
 344         }
 345     }
 346 }
 347
 348 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
 349     fn eval_closure_size(&mut self) {
 350         let mut res: FxHashMap<DefId, ClosureSizeProfileData<'tcx>> = Default::default();
 351         for (closure_def_id, data) in self.fcx.typeck_results.borrow().closure_size_eval.iter() {
 352             let closure_hir_id =
 353                 self.tcx().hir().local_def_id_to_hir_id(closure_def_id.expect_local());
 354
 355             let data = self.resolve(*data, &closure_hir_id);
 356
 357             res.insert(*closure_def_id, data);
 358         }
 359
 360         self.typeck_results.closure_size_eval = res;
 361     }
 362     fn visit_min_capture_map(&mut self) {
 363         let mut min_captures_wb = ty::MinCaptureInformationMap::with_capacity_and_hasher(
 364             self.fcx.typeck_results.borrow().closure_min_captures.len(),
 365             Default::default(),
 366         );
 367         for (closure_def_id, root_min_captures) in
 368             self.fcx.typeck_results.borrow().closure_min_captures.iter()
 369         {
 370             let mut root_var_map_wb = ty::RootVariableMinCaptureList::with_capacity_and_hasher(
 371                 root_min_captures.len(),
 372                 Default::default(),
 373             );
 374             for (var_hir_id, min_list) in root_min_captures.iter() {
 375                 let min_list_wb = min_list
 376                     .iter()
 377                     .map(|captured_place| {
 378                         let locatable = captured_place.info.path_expr_id.unwrap_or_else(|| {
 379                             self.tcx().hir().local_def_id_to_hir_id(closure_def_id.expect_local())
 380                         });
 381
 382                         self.resolve(captured_place.clone(), &locatable)
 383                     })
 384                     .collect();
 385                 root_var_map_wb.insert(*var_hir_id, min_list_wb);
 386             }
 387             min_captures_wb.insert(*closure_def_id, root_var_map_wb);
 388         }
 389
 390         self.typeck_results.closure_min_captures = min_captures_wb;
 391     }
 392
 393     fn visit_fake_reads_map(&mut self) {
 394         let mut resolved_closure_fake_reads: FxHashMap<
 395             DefId,
 396             Vec<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>,
 397         > = Default::default();
 398         for (closure_def_id, fake_reads) in
 399             self.fcx.typeck_results.borrow().closure_fake_reads.iter()
 400         {
 401             let mut resolved_fake_reads = Vec::<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>::new();
 402             for (place, cause, hir_id) in fake_reads.iter() {
 403                 let locatable =
 404                     self.tcx().hir().local_def_id_to_hir_id(closure_def_id.expect_local());
 405
 406                 let resolved_fake_read = self.resolve(place.clone(), &locatable);
 407                 resolved_fake_reads.push((resolved_fake_read, *cause, *hir_id));
 408             }
 409             resolved_closure_fake_reads.insert(*closure_def_id, resolved_fake_reads);
 410         }
 411         self.typeck_results.closure_fake_reads = resolved_closure_fake_reads;
 412     }
 413
 414     fn visit_closures(&mut self) {
 415         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 416         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 417         let common_hir_owner = fcx_typeck_results.hir_owner;
 418
 419         for (id, origin) in fcx_typeck_results.closure_kind_origins().iter() {
 420             let hir_id = hir::HirId { owner: common_hir_owner, local_id: *id };
 421             let place_span = origin.0;
 422             let place = self.resolve(origin.1.clone(), &place_span);
 423             self.typeck_results.closure_kind_origins_mut().insert(hir_id, (place_span, place));
 424         }
 425     }
 426
 427     fn visit_coercion_casts(&mut self) {
 428         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 429         let fcx_coercion_casts = fcx_typeck_results.coercion_casts();
 430         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 431
 432         for local_id in fcx_coercion_casts {
 433             self.typeck_results.set_coercion_cast(*local_id);
 434         }
 435     }
 436
 437     fn visit_user_provided_tys(&mut self) {
 438         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 439         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 440         let common_hir_owner = fcx_typeck_results.hir_owner;
 441
 442         let mut errors_buffer = Vec::new();
 443         for (&local_id, c_ty) in fcx_typeck_results.user_provided_types().iter() {
 444             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 445
 446             if cfg!(debug_assertions) && c_ty.needs_infer() {
 447                 span_bug!(
 448                     hir_id.to_span(self.fcx.tcx),
 449                     "writeback: `{:?}` has inference variables",
 450                     c_ty
 451                 );
 452             };
 453
 454             self.typeck_results.user_provided_types_mut().insert(hir_id, *c_ty);
 455
 456             if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
 457                 if self.rustc_dump_user_substs {
 458                     // This is a unit-testing mechanism.
 459                     let span = self.tcx().hir().span(hir_id);
 460                     // We need to buffer the errors in order to guarantee a consistent
 461                     // order when emitting them.
 462                     let err = self
 463                         .tcx()
 464                         .sess
 465                         .struct_span_err(span, &format!("user substs: {:?}", user_substs));
 466                     err.buffer(&mut errors_buffer);
 467                 }
 468             }
 469         }
 470
 471         if !errors_buffer.is_empty() {
 472             errors_buffer.sort_by_key(|diag| diag.span.primary_span());
 473             for mut diag in errors_buffer.drain(..) {
 474                 self.tcx().sess.diagnostic().emit_diagnostic(&mut diag);
 475             }
 476         }
 477     }
 478
 479     fn visit_user_provided_sigs(&mut self) {
 480         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 481         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 482
 483         for (&def_id, c_sig) in fcx_typeck_results.user_provided_sigs.iter() {
 484             if cfg!(debug_assertions) && c_sig.needs_infer() {
 485                 span_bug!(
 486                     self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
 487                     "writeback: `{:?}` has inference variables",
 488                     c_sig
 489                 );
 490             };
 491
 492             self.typeck_results.user_provided_sigs.insert(def_id, *c_sig);
 493         }
 494     }
 495
 496     fn visit_generator_interior_types(&mut self) {
 497         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 498         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 499         self.typeck_results.generator_interior_types =
 500             fcx_typeck_results.generator_interior_types.clone();
 501     }
 502
 503     #[instrument(skip(self), level = "debug")]
 504     fn visit_opaque_types(&mut self) {
 505         let opaque_types =
 506             self.fcx.infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
 507         for (opaque_type_key, decl) in opaque_types {
 508             let hidden_type = match decl.origin {
 509                 hir::OpaqueTyOrigin::FnReturn(_) | hir::OpaqueTyOrigin::AsyncFn(_) => {
 510                     let ty = self.resolve(decl.hidden_type.ty, &decl.hidden_type.span);
 511                     struct RecursionChecker {
 512                         def_id: DefId,
 513                     }
 514                     impl<'tcx> ty::TypeVisitor<'tcx> for RecursionChecker {
 515                         type BreakTy = ();
 516                         fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
 517                             if let ty::Opaque(def_id, _) = *t.kind() {
 518                                 if def_id == self.def_id {
 519                                     return ControlFlow::Break(());
 520                                 }
 521                             }
 522                             t.super_visit_with(self)
 523                         }
 524                     }
 525                     if ty
 526                         .visit_with(&mut RecursionChecker { def_id: opaque_type_key.def_id })
 527                         .is_break()
 528                     {
 529                         return;
 530                     }
 531                     Some(ty)
 532                 }
 533                 hir::OpaqueTyOrigin::TyAlias => None,
 534             };
 535             self.typeck_results.concrete_opaque_types.insert(opaque_type_key.def_id, hidden_type);
 536         }
 537     }
 538
 539     fn visit_field_id(&mut self, hir_id: hir::HirId) {
 540         if let Some(index) = self.fcx.typeck_results.borrow_mut().field_indices_mut().remove(hir_id)
 541         {
 542             self.typeck_results.field_indices_mut().insert(hir_id, index);
 543         }
 544     }
 545
 546     #[instrument(skip(self, span), level = "debug")]
 547     fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
 548         // Export associated path extensions and method resolutions.
 549         if let Some(def) =
 550             self.fcx.typeck_results.borrow_mut().type_dependent_defs_mut().remove(hir_id)
 551         {
 552             self.typeck_results.type_dependent_defs_mut().insert(hir_id, def);
 553         }
 554
 555         // Resolve any borrowings for the node with id `node_id`
 556         self.visit_adjustments(span, hir_id);
 557
 558         // Resolve the type of the node with id `node_id`
 559         let n_ty = self.fcx.node_ty(hir_id);
 560         let n_ty = self.resolve(n_ty, &span);
 561         self.write_ty_to_typeck_results(hir_id, n_ty);
 562         debug!(?n_ty);
 563
 564         // Resolve any substitutions
 565         if let Some(substs) = self.fcx.typeck_results.borrow().node_substs_opt(hir_id) {
 566             let substs = self.resolve(substs, &span);
 567             debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
 568             assert!(!substs.needs_infer() && !substs.has_placeholders());
 569             self.typeck_results.node_substs_mut().insert(hir_id, substs);
 570         }
 571     }
 572
 573     #[instrument(skip(self, span), level = "debug")]
 574     fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 575         let adjustment = self.fcx.typeck_results.borrow_mut().adjustments_mut().remove(hir_id);
 576         match adjustment {
 577             None => {
 578                 debug!("no adjustments for node");
 579             }
 580
 581             Some(adjustment) => {
 582                 let resolved_adjustment = self.resolve(adjustment, &span);
 583                 debug!(?resolved_adjustment);
 584                 self.typeck_results.adjustments_mut().insert(hir_id, resolved_adjustment);
 585             }
 586         }
 587     }
 588
 589     #[instrument(skip(self, span), level = "debug")]
 590     fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 591         let adjustment = self.fcx.typeck_results.borrow_mut().pat_adjustments_mut().remove(hir_id);
 592         match adjustment {
 593             None => {
 594                 debug!("no pat_adjustments for node");
 595             }
 596
 597             Some(adjustment) => {
 598                 let resolved_adjustment = self.resolve(adjustment, &span);
 599                 debug!(?resolved_adjustment);
 600                 self.typeck_results.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
 601             }
 602         }
 603     }
 604
 605     fn visit_liberated_fn_sigs(&mut self) {
 606         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 607         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 608         let common_hir_owner = fcx_typeck_results.hir_owner;
 609
 610         for (&local_id, &fn_sig) in fcx_typeck_results.liberated_fn_sigs().iter() {
 611             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 612             let fn_sig = self.resolve(fn_sig, &hir_id);
 613             self.typeck_results.liberated_fn_sigs_mut().insert(hir_id, fn_sig);
 614         }
 615     }
 616
 617     fn visit_fru_field_types(&mut self) {
 618         let fcx_typeck_results = self.fcx.typeck_results.borrow();
 619         assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
 620         let common_hir_owner = fcx_typeck_results.hir_owner;
 621
 622         for (&local_id, ftys) in fcx_typeck_results.fru_field_types().iter() {
 623             let hir_id = hir::HirId { owner: common_hir_owner, local_id };
 624             let ftys = self.resolve(ftys.clone(), &hir_id);
 625             self.typeck_results.fru_field_types_mut().insert(hir_id, ftys);
 626         }
 627     }
 628
 629     fn resolve<T>(&mut self, x: T, span: &dyn Locatable) -> T
 630     where
 631         T: TypeFoldable<'tcx>,
 632     {
 633         let mut resolver = Resolver::new(self.fcx, span, self.body);
 634         let x = x.fold_with(&mut resolver);
 635         if cfg!(debug_assertions) && x.needs_infer() {
 636             span_bug!(span.to_span(self.fcx.tcx), "writeback: `{:?}` has inference variables", x);
 637         }
 638
 639         // We may have introduced e.g. `ty::Error`, if inference failed, make sure
 640         // to mark the `TypeckResults` as tainted in that case, so that downstream
 641         // users of the typeck results don't produce extra errors, or worse, ICEs.
 642         if resolver.replaced_with_error {
 643             // FIXME(eddyb) keep track of `ErrorGuaranteed` from where the error was emitted.
 644             self.typeck_results.tainted_by_errors =
 645                 Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
 646         }
 647
 648         x
 649     }
 650 }
 651
 652 pub(crate) trait Locatable {
 653     fn to_span(&self, tcx: TyCtxt<'_>) -> Span;
 654 }
 655
 656 impl Locatable for Span {
 657     fn to_span(&self, _: TyCtxt<'_>) -> Span {
 658         *self
 659     }
 660 }
 661
 662 impl Locatable for hir::HirId {
 663     fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
 664         tcx.hir().span(*self)
 665     }
 666 }
 667
 668 /// The Resolver. This is the type folding engine that detects
 669 /// unresolved types and so forth.
 670 struct Resolver<'cx, 'tcx> {
 671     tcx: TyCtxt<'tcx>,
 672     infcx: &'cx InferCtxt<'cx, 'tcx>,
 673     span: &'cx dyn Locatable,
 674     body: &'tcx hir::Body<'tcx>,
 675
 676     /// Set to `true` if any `Ty` or `ty::Const` had to be replaced with an `Error`.
 677     replaced_with_error: bool,
 678 }
 679
 680 impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
 681     fn new(
 682         fcx: &'cx FnCtxt<'cx, 'tcx>,
 683         span: &'cx dyn Locatable,
 684         body: &'tcx hir::Body<'tcx>,
 685     ) -> Resolver<'cx, 'tcx> {
 686         Resolver { tcx: fcx.tcx, infcx: fcx, span, body, replaced_with_error: false }
 687     }
 688
 689     fn report_type_error(&self, t: Ty<'tcx>) {
 690         if !self.tcx.sess.has_errors().is_some() {
 691             self.infcx
 692                 .emit_inference_failure_err(
 693                     Some(self.body.id()),
 694                     self.span.to_span(self.tcx),
 695                     t.into(),
 696                     E0282,
 697                     false,
 698                 )
 699                 .emit();
 700         }
 701     }
 702
 703     fn report_const_error(&self, c: ty::Const<'tcx>) {
 704         if self.tcx.sess.has_errors().is_none() {
 705             self.infcx
 706                 .emit_inference_failure_err(
 707                     Some(self.body.id()),
 708                     self.span.to_span(self.tcx),
 709                     c.into(),
 710                     E0282,
 711                     false,
 712                 )
 713                 .emit();
 714         }
 715     }
 716 }
 717
 718 struct EraseEarlyRegions<'tcx> {
 719     tcx: TyCtxt<'tcx>,
 720 }
 721
 722 impl<'tcx> TypeFolder<'tcx> for EraseEarlyRegions<'tcx> {
 723     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
 724         self.tcx
 725     }
 726     fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
 727         if ty.has_type_flags(ty::TypeFlags::HAS_FREE_REGIONS) {
 728             ty.super_fold_with(self)
 729         } else {
 730             ty
 731         }
 732     }
 733     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
 734         if r.is_late_bound() { r } else { self.tcx.lifetimes.re_erased }
 735     }
 736 }
 737
 738 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
 739     fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
 740         self.tcx
 741     }
 742
 743     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
 744         match self.infcx.fully_resolve(t) {
 745             Ok(t) => {
 746                 // Do not anonymize late-bound regions
 747                 // (e.g. keep `for<'a>` named `for<'a>`).
 748                 // This allows NLL to generate error messages that
 749                 // refer to the higher-ranked lifetime names written by the user.
 750                 EraseEarlyRegions { tcx: self.infcx.tcx }.fold_ty(t)
 751             }
 752             Err(_) => {
 753                 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable", t);
 754                 self.report_type_error(t);
 755                 self.replaced_with_error = true;
 756                 self.tcx().ty_error()
 757             }
 758         }
 759     }
 760
 761     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
 762         debug_assert!(!r.is_late_bound(), "Should not be resolving bound region.");
 763         self.tcx.lifetimes.re_erased
 764     }
 765
 766     fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
 767         match self.infcx.fully_resolve(ct) {
 768             Ok(ct) => self.infcx.tcx.erase_regions(ct),
 769             Err(_) => {
 770                 debug!("Resolver::fold_const: input const `{:?}` not fully resolvable", ct);
 771                 self.report_const_error(ct);
 772                 self.replaced_with_error = true;
 773                 self.tcx().const_error(ct.ty())
 774             }
 775         }
 776     }
 777 }
 778
 779 ///////////////////////////////////////////////////////////////////////////
 780 // During type check, we store promises with the result of trait
 781 // lookup rather than the actual results (because the results are not
 782 // necessarily available immediately). These routines unwind the
 783 // promises. It is expected that we will have already reported any
 784 // errors that may be encountered, so if the promises store an error,
 785 // a dummy result is returned.