src/librustc_typeck/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 use errors::DiagnosticBuilder;
   7 use rustc::hir;
   8 use rustc::hir::def_id::{DefId, DefIndex};
   9 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
  10 use rustc::infer::InferCtxt;
  11 use rustc::ty::adjustment::{Adjust, Adjustment, PointerCast};
  12 use rustc::ty::fold::{BottomUpFolder, TypeFoldable, TypeFolder};
  13 use rustc::ty::subst::UnpackedKind;
  14 use rustc::ty::{self, Ty, TyCtxt};
  15 use rustc::util::nodemap::DefIdSet;
  16 use rustc_data_structures::sync::Lrc;
  17 use std::mem;
  18 use syntax_pos::Span;
  19
  20 ///////////////////////////////////////////////////////////////////////////
  21 // Entry point
  22
  23 // During type inference, partially inferred types are
  24 // represented using Type variables (ty::Infer). These don't appear in
  25 // the final TypeckTables since all of the types should have been
  26 // inferred once typeck_tables_of is done.
  27 // When type inference is running however, having to update the typeck
  28 // tables every time a new type is inferred would be unreasonably slow,
  29 // so instead all of the replacement happens at the end in
  30 // resolve_type_vars_in_body, which creates a new TypeTables which
  31 // doesn't contain any inference types.
  32 impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
  33     pub fn resolve_type_vars_in_body(&self, body: &'gcx hir::Body) -> &'gcx ty::TypeckTables<'gcx> {
  34         let item_id = self.tcx.hir().body_owner(body.id());
  35         let item_def_id = self.tcx.hir().local_def_id(item_id);
  36
  37         // This attribute causes us to dump some writeback information
  38         // in the form of errors, which is used for unit tests.
  39         let rustc_dump_user_substs = self.tcx.has_attr(item_def_id, "rustc_dump_user_substs");
  40
  41         let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_substs);
  42         for arg in &body.arguments {
  43             wbcx.visit_node_id(arg.pat.span, arg.hir_id);
  44         }
  45         wbcx.visit_body(body);
  46         wbcx.visit_upvar_capture_map();
  47         wbcx.visit_upvar_list_map();
  48         wbcx.visit_closures();
  49         wbcx.visit_liberated_fn_sigs();
  50         wbcx.visit_fru_field_types();
  51         wbcx.visit_opaque_types(body.value.span);
  52         wbcx.visit_coercion_casts();
  53         wbcx.visit_free_region_map();
  54         wbcx.visit_user_provided_tys();
  55         wbcx.visit_user_provided_sigs();
  56
  57         let used_trait_imports = mem::replace(
  58             &mut self.tables.borrow_mut().used_trait_imports,
  59             Lrc::new(DefIdSet::default()),
  60         );
  61         debug!(
  62             "used_trait_imports({:?}) = {:?}",
  63             item_def_id, used_trait_imports
  64         );
  65         wbcx.tables.used_trait_imports = used_trait_imports;
  66
  67         wbcx.tables.tainted_by_errors = self.is_tainted_by_errors();
  68
  69         debug!(
  70             "writeback: tables for {:?} are {:#?}",
  71             item_def_id, wbcx.tables
  72         );
  73
  74         self.tcx.alloc_tables(wbcx.tables)
  75     }
  76 }
  77
  78 ///////////////////////////////////////////////////////////////////////////
  79 // The Writeback context. This visitor walks the AST, checking the
  80 // fn-specific tables to find references to types or regions. It
  81 // resolves those regions to remove inference variables and writes the
  82 // final result back into the master tables in the tcx. Here and
  83 // there, it applies a few ad-hoc checks that were not convenient to
  84 // do elsewhere.
  85
  86 struct WritebackCx<'cx, 'gcx: 'cx + 'tcx, 'tcx: 'cx> {
  87     fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
  88
  89     tables: ty::TypeckTables<'gcx>,
  90
  91     body: &'gcx hir::Body,
  92
  93     rustc_dump_user_substs: bool,
  94 }
  95
  96 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
  97     fn new(
  98         fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
  99         body: &'gcx hir::Body,
 100         rustc_dump_user_substs: bool,
 101     ) -> WritebackCx<'cx, 'gcx, 'tcx> {
 102         let owner = body.id().hir_id;
 103
 104         WritebackCx {
 105             fcx,
 106             tables: ty::TypeckTables::empty(Some(DefId::local(owner.owner))),
 107             body,
 108             rustc_dump_user_substs,
 109         }
 110     }
 111
 112     fn tcx(&self) -> TyCtxt<'cx, 'gcx, 'tcx> {
 113         self.fcx.tcx
 114     }
 115
 116     fn write_ty_to_tables(&mut self, hir_id: hir::HirId, ty: Ty<'gcx>) {
 117         debug!("write_ty_to_tables({:?}, {:?})", hir_id, ty);
 118         assert!(!ty.needs_infer() && !ty.has_placeholders());
 119         self.tables.node_types_mut().insert(hir_id, ty);
 120     }
 121
 122     // Hacky hack: During type-checking, we treat *all* operators
 123     // as potentially overloaded. But then, during writeback, if
 124     // we observe that something like `a+b` is (known to be)
 125     // operating on scalars, we clear the overload.
 126     fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr) {
 127         match e.node {
 128             hir::ExprKind::Unary(hir::UnNeg, ref inner)
 129             | hir::ExprKind::Unary(hir::UnNot, ref inner) => {
 130                 let inner_ty = self.fcx.node_ty(inner.hir_id);
 131                 let inner_ty = self.fcx.resolve_type_vars_if_possible(&inner_ty);
 132
 133                 if inner_ty.is_scalar() {
 134                     let mut tables = self.fcx.tables.borrow_mut();
 135                     tables.type_dependent_defs_mut().remove(e.hir_id);
 136                     tables.node_substs_mut().remove(e.hir_id);
 137                 }
 138             }
 139             hir::ExprKind::Binary(ref op, ref lhs, ref rhs)
 140             | hir::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
 141                 let lhs_ty = self.fcx.node_ty(lhs.hir_id);
 142                 let lhs_ty = self.fcx.resolve_type_vars_if_possible(&lhs_ty);
 143
 144                 let rhs_ty = self.fcx.node_ty(rhs.hir_id);
 145                 let rhs_ty = self.fcx.resolve_type_vars_if_possible(&rhs_ty);
 146
 147                 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
 148                     let mut tables = self.fcx.tables.borrow_mut();
 149                     tables.type_dependent_defs_mut().remove(e.hir_id);
 150                     tables.node_substs_mut().remove(e.hir_id);
 151
 152                     match e.node {
 153                         hir::ExprKind::Binary(..) => {
 154                             if !op.node.is_by_value() {
 155                                 let mut adjustments = tables.adjustments_mut();
 156                                 adjustments.get_mut(lhs.hir_id).map(|a| a.pop());
 157                                 adjustments.get_mut(rhs.hir_id).map(|a| a.pop());
 158                             }
 159                         }
 160                         hir::ExprKind::AssignOp(..) => {
 161                             tables
 162                                 .adjustments_mut()
 163                                 .get_mut(lhs.hir_id)
 164                                 .map(|a| a.pop());
 165                         }
 166                         _ => {}
 167                     }
 168                 }
 169             }
 170             _ => {}
 171         }
 172     }
 173
 174     // Similar to operators, indexing is always assumed to be overloaded
 175     // Here, correct cases where an indexing expression can be simplified
 176     // to use builtin indexing because the index type is known to be
 177     // usize-ish
 178     fn fix_index_builtin_expr(&mut self, e: &hir::Expr) {
 179         if let hir::ExprKind::Index(ref base, ref index) = e.node {
 180             let mut tables = self.fcx.tables.borrow_mut();
 181
 182             // All valid indexing looks like this; might encounter non-valid indexes at this point
 183             if let ty::Ref(_, base_ty, _) = tables.expr_ty_adjusted(&base).sty {
 184                 let index_ty = tables.expr_ty_adjusted(&index);
 185                 let index_ty = self.fcx.resolve_type_vars_if_possible(&index_ty);
 186
 187                 if base_ty.builtin_index().is_some() && index_ty == self.fcx.tcx.types.usize {
 188                     // Remove the method call record
 189                     tables.type_dependent_defs_mut().remove(e.hir_id);
 190                     tables.node_substs_mut().remove(e.hir_id);
 191
 192                     tables.adjustments_mut().get_mut(base.hir_id).map(|a| {
 193                         // Discard the need for a mutable borrow
 194                         match a.pop() {
 195                             // Extra adjustment made when indexing causes a drop
 196                             // of size information - we need to get rid of it
 197                             // Since this is "after" the other adjustment to be
 198                             // discarded, we do an extra `pop()`
 199                             Some(Adjustment {
 200                                 kind: Adjust::Pointer(PointerCast::Unsize),
 201                                 ..
 202                             }) => {
 203                                 // So the borrow discard actually happens here
 204                                 a.pop();
 205                             }
 206                             _ => {}
 207                         }
 208                     });
 209                 }
 210             }
 211         }
 212     }
 213 }
 214
 215 ///////////////////////////////////////////////////////////////////////////
 216 // Impl of Visitor for Resolver
 217 //
 218 // This is the master code which walks the AST. It delegates most of
 219 // the heavy lifting to the generic visit and resolve functions
 220 // below. In general, a function is made into a `visitor` if it must
 221 // traffic in node-ids or update tables in the type context etc.
 222
 223 impl<'cx, 'gcx, 'tcx> Visitor<'gcx> for WritebackCx<'cx, 'gcx, 'tcx> {
 224     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
 225         NestedVisitorMap::None
 226     }
 227
 228     fn visit_expr(&mut self, e: &'gcx hir::Expr) {
 229         self.fix_scalar_builtin_expr(e);
 230         self.fix_index_builtin_expr(e);
 231
 232         self.visit_node_id(e.span, e.hir_id);
 233
 234         match e.node {
 235             hir::ExprKind::Closure(_, _, body, _, _) => {
 236                 let body = self.fcx.tcx.hir().body(body);
 237                 for arg in &body.arguments {
 238                     self.visit_node_id(e.span, arg.hir_id);
 239                 }
 240
 241                 self.visit_body(body);
 242             }
 243             hir::ExprKind::Struct(_, ref fields, _) => {
 244                 for field in fields {
 245                     self.visit_field_id(field.hir_id);
 246                 }
 247             }
 248             hir::ExprKind::Field(..) => {
 249                 self.visit_field_id(e.hir_id);
 250             }
 251             _ => {}
 252         }
 253
 254         intravisit::walk_expr(self, e);
 255     }
 256
 257     fn visit_block(&mut self, b: &'gcx hir::Block) {
 258         self.visit_node_id(b.span, b.hir_id);
 259         intravisit::walk_block(self, b);
 260     }
 261
 262     fn visit_pat(&mut self, p: &'gcx hir::Pat) {
 263         match p.node {
 264             hir::PatKind::Binding(..) => {
 265                 if let Some(&bm) = self.fcx.tables.borrow().pat_binding_modes().get(p.hir_id) {
 266                     self.tables.pat_binding_modes_mut().insert(p.hir_id, bm);
 267                 } else {
 268                     self.tcx()
 269                         .sess
 270                         .delay_span_bug(p.span, "missing binding mode");
 271                 }
 272             }
 273             hir::PatKind::Struct(_, ref fields, _) => {
 274                 for field in fields {
 275                     self.visit_field_id(field.node.hir_id);
 276                 }
 277             }
 278             _ => {}
 279         };
 280
 281         self.visit_pat_adjustments(p.span, p.hir_id);
 282
 283         self.visit_node_id(p.span, p.hir_id);
 284         intravisit::walk_pat(self, p);
 285     }
 286
 287     fn visit_local(&mut self, l: &'gcx hir::Local) {
 288         intravisit::walk_local(self, l);
 289         let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
 290         let var_ty = self.resolve(&var_ty, &l.span);
 291         self.write_ty_to_tables(l.hir_id, var_ty);
 292     }
 293
 294     fn visit_ty(&mut self, hir_ty: &'gcx hir::Ty) {
 295         intravisit::walk_ty(self, hir_ty);
 296         let ty = self.fcx.node_ty(hir_ty.hir_id);
 297         let ty = self.resolve(&ty, &hir_ty.span);
 298         self.write_ty_to_tables(hir_ty.hir_id, ty);
 299     }
 300
 301     fn visit_argument_source(&mut self, s: &'gcx hir::ArgSource) {
 302         match s {
 303             // Don't visit the pattern in `ArgSource::AsyncFn`, it contains a pattern which has
 304             // a `NodeId` w/out a type, as it is only used for getting the name of the original
 305             // pattern for diagnostics where only an `hir::Arg` is present.
 306             hir::ArgSource::AsyncFn(..) => {},
 307             _ => intravisit::walk_argument_source(self, s),
 308         }
 309     }
 310 }
 311
 312 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
 313     fn visit_upvar_capture_map(&mut self) {
 314         for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
 315             let new_upvar_capture = match *upvar_capture {
 316                 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
 317                 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
 318                     let r = upvar_borrow.region;
 319                     let r = self.resolve(&r, &upvar_id.var_path.hir_id);
 320                     ty::UpvarCapture::ByRef(ty::UpvarBorrow {
 321                         kind: upvar_borrow.kind,
 322                         region: r,
 323                     })
 324                 }
 325             };
 326             debug!(
 327                 "Upvar capture for {:?} resolved to {:?}",
 328                 upvar_id, new_upvar_capture
 329             );
 330             self.tables
 331                 .upvar_capture_map
 332                 .insert(*upvar_id, new_upvar_capture);
 333         }
 334     }
 335
 336     /// Runs through the function context's upvar list map and adds the same to
 337     /// the TypeckTables. upvarlist is a hashmap of the list of upvars referred
 338     /// to in a closure..
 339     fn visit_upvar_list_map(&mut self) {
 340         for (closure_def_id, upvar_list) in self.fcx.tables.borrow().upvar_list.iter() {
 341             debug!(
 342                 "UpvarIDs captured by closure {:?} are: {:?}",
 343                 closure_def_id, upvar_list
 344             );
 345             self.tables
 346                 .upvar_list
 347                 .insert(*closure_def_id, upvar_list.to_vec());
 348         }
 349     }
 350
 351     fn visit_closures(&mut self) {
 352         let fcx_tables = self.fcx.tables.borrow();
 353         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 354         let common_local_id_root = fcx_tables.local_id_root.unwrap();
 355
 356         for (&id, &origin) in fcx_tables.closure_kind_origins().iter() {
 357             let hir_id = hir::HirId {
 358                 owner: common_local_id_root.index,
 359                 local_id: id,
 360             };
 361             self.tables
 362                 .closure_kind_origins_mut()
 363                 .insert(hir_id, origin);
 364         }
 365     }
 366
 367     fn visit_coercion_casts(&mut self) {
 368         let fcx_tables = self.fcx.tables.borrow();
 369         let fcx_coercion_casts = fcx_tables.coercion_casts();
 370         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 371
 372         for local_id in fcx_coercion_casts {
 373             self.tables.set_coercion_cast(*local_id);
 374         }
 375     }
 376
 377     fn visit_free_region_map(&mut self) {
 378         let free_region_map = self.tcx()
 379             .lift_to_global(&self.fcx.tables.borrow().free_region_map);
 380         let free_region_map = free_region_map.expect("all regions in free-region-map are global");
 381         self.tables.free_region_map = free_region_map;
 382     }
 383
 384     fn visit_user_provided_tys(&mut self) {
 385         let fcx_tables = self.fcx.tables.borrow();
 386         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 387         let common_local_id_root = fcx_tables.local_id_root.unwrap();
 388
 389         let mut errors_buffer = Vec::new();
 390         for (&local_id, c_ty) in fcx_tables.user_provided_types().iter() {
 391             let hir_id = hir::HirId {
 392                 owner: common_local_id_root.index,
 393                 local_id,
 394             };
 395
 396             let c_ty = if let Some(c_ty) = self.tcx().lift_to_global(c_ty) {
 397                 c_ty
 398             } else {
 399                 span_bug!(
 400                     hir_id.to_span(&self.fcx.tcx),
 401                     "writeback: `{:?}` missing from the global type context",
 402                     c_ty
 403                 );
 404             };
 405
 406             self.tables
 407                 .user_provided_types_mut()
 408                 .insert(hir_id, c_ty.clone());
 409
 410             if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
 411                 if self.rustc_dump_user_substs {
 412                     // This is a unit-testing mechanism.
 413                     let span = self.tcx().hir().span_by_hir_id(hir_id);
 414                     // We need to buffer the errors in order to guarantee a consistent
 415                     // order when emitting them.
 416                     let err = self.tcx().sess.struct_span_err(
 417                         span,
 418                         &format!("user substs: {:?}", user_substs)
 419                     );
 420                     err.buffer(&mut errors_buffer);
 421                 }
 422             }
 423         }
 424
 425         if !errors_buffer.is_empty() {
 426             errors_buffer.sort_by_key(|diag| diag.span.primary_span());
 427             for diag in errors_buffer.drain(..) {
 428                 DiagnosticBuilder::new_diagnostic(self.tcx().sess.diagnostic(), diag).emit();
 429             }
 430         }
 431     }
 432
 433     fn visit_user_provided_sigs(&mut self) {
 434         let fcx_tables = self.fcx.tables.borrow();
 435         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 436
 437         for (&def_id, c_sig) in fcx_tables.user_provided_sigs.iter() {
 438             let c_sig = if let Some(c_sig) = self.tcx().lift_to_global(c_sig) {
 439                 c_sig
 440             } else {
 441                 span_bug!(
 442                     self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
 443                     "writeback: `{:?}` missing from the global type context",
 444                     c_sig
 445                 );
 446             };
 447
 448             self.tables
 449                 .user_provided_sigs
 450                 .insert(def_id, c_sig.clone());
 451         }
 452     }
 453
 454     fn visit_opaque_types(&mut self, span: Span) {
 455         for (&def_id, opaque_defn) in self.fcx.opaque_types.borrow().iter() {
 456             let hir_id = self.tcx().hir().as_local_hir_id(def_id).unwrap();
 457             let instantiated_ty = self.resolve(&opaque_defn.concrete_ty, &hir_id);
 458
 459             let generics = self.tcx().generics_of(def_id);
 460
 461             let definition_ty = if generics.parent.is_some() {
 462                 // impl trait
 463                 self.fcx.infer_opaque_definition_from_instantiation(
 464                     def_id,
 465                     opaque_defn,
 466                     instantiated_ty,
 467                 )
 468             } else {
 469                 // prevent
 470                 // * `fn foo<T>() -> Foo<T>`
 471                 // * `fn foo<T: Bound + Other>() -> Foo<T>`
 472                 // from being defining
 473
 474                 // Also replace all generic params with the ones from the existential type
 475                 // definition so
 476                 // ```rust
 477                 // existential type Foo<T>: 'static;
 478                 // fn foo<U>() -> Foo<U> { .. }
 479                 // ```
 480                 // figures out the concrete type with `U`, but the stored type is with `T`
 481                 instantiated_ty.fold_with(&mut BottomUpFolder {
 482                     tcx: self.tcx().global_tcx(),
 483                     fldop: |ty| {
 484                         trace!("checking type {:?}", ty);
 485                         // find a type parameter
 486                         if let ty::Param(..) = ty.sty {
 487                             // look it up in the substitution list
 488                             assert_eq!(opaque_defn.substs.len(), generics.params.len());
 489                             for (subst, param) in opaque_defn.substs.iter().zip(&generics.params) {
 490                                 if let UnpackedKind::Type(subst) = subst.unpack() {
 491                                     if subst == ty {
 492                                         // found it in the substitution list, replace with the
 493                                         // parameter from the existential type
 494                                         return self.tcx()
 495                                             .global_tcx()
 496                                             .mk_ty_param(param.index, param.name);
 497                                     }
 498                                 }
 499                             }
 500                             self.tcx()
 501                                 .sess
 502                                 .struct_span_err(
 503                                     span,
 504                                     &format!(
 505                                         "type parameter `{}` is part of concrete type but not used \
 506                                          in parameter list for existential type",
 507                                         ty,
 508                                     ),
 509                                 )
 510                                 .emit();
 511                             return self.tcx().types.err;
 512                         }
 513                         ty
 514                     },
 515                     reg_op: |region| {
 516                         match region {
 517                             // ignore static regions
 518                             ty::ReStatic => region,
 519                             _ => {
 520                                 trace!("checking {:?}", region);
 521                                 for (subst, p) in opaque_defn.substs.iter().zip(&generics.params) {
 522                                     if let UnpackedKind::Lifetime(subst) = subst.unpack() {
 523                                         if subst == region {
 524                                             // found it in the substitution list, replace with the
 525                                             // parameter from the existential type
 526                                             let reg = ty::EarlyBoundRegion {
 527                                                 def_id: p.def_id,
 528                                                 index: p.index,
 529                                                 name: p.name,
 530                                             };
 531                                             trace!("replace {:?} with {:?}", region, reg);
 532                                             return self.tcx()
 533                                                 .global_tcx()
 534                                                 .mk_region(ty::ReEarlyBound(reg));
 535                                         }
 536                                     }
 537                                 }
 538                                 trace!("opaque_defn: {:#?}", opaque_defn);
 539                                 trace!("generics: {:#?}", generics);
 540                                 self.tcx()
 541                                     .sess
 542                                     .struct_span_err(
 543                                         span,
 544                                         "non-defining existential type use in defining scope",
 545                                     )
 546                                     .span_label(
 547                                         span,
 548                                         format!(
 549                                             "lifetime `{}` is part of concrete type but not used \
 550                                              in parameter list of existential type",
 551                                             region,
 552                                         ),
 553                                     )
 554                                     .emit();
 555                                 self.tcx().global_tcx().mk_region(ty::ReStatic)
 556                             }
 557                         }
 558                     },
 559                 })
 560             };
 561
 562             if let ty::Opaque(defin_ty_def_id, _substs) = definition_ty.sty {
 563                 if def_id == defin_ty_def_id {
 564                     // Concrete type resolved to the existential type itself
 565                     // Force a cycle error
 566                     // FIXME(oli-obk): we could just not insert it into `concrete_existential_types`
 567                     // which simply would make this use not a defining use.
 568                     self.tcx().at(span).type_of(defin_ty_def_id);
 569                 }
 570             }
 571
 572             let new = ty::ResolvedOpaqueTy {
 573                 concrete_type: definition_ty,
 574                 substs: self.tcx().lift_to_global(&opaque_defn.substs).unwrap(),
 575             };
 576
 577             let old = self.tables
 578                 .concrete_existential_types
 579                 .insert(def_id, new);
 580             if let Some(old) = old {
 581                 if old.concrete_type != definition_ty || old.substs != opaque_defn.substs {
 582                     span_bug!(
 583                         span,
 584                         "visit_opaque_types tried to write \
 585                         different types for the same existential type: {:?}, {:?}, {:?}, {:?}",
 586                         def_id,
 587                         definition_ty,
 588                         opaque_defn,
 589                         old,
 590                     );
 591                 }
 592             }
 593         }
 594     }
 595
 596     fn visit_field_id(&mut self, hir_id: hir::HirId) {
 597         if let Some(index) = self.fcx
 598             .tables
 599             .borrow_mut()
 600             .field_indices_mut()
 601             .remove(hir_id)
 602         {
 603             self.tables.field_indices_mut().insert(hir_id, index);
 604         }
 605     }
 606
 607     fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
 608         // Export associated path extensions and method resolutions.
 609         if let Some(def) = self.fcx
 610             .tables
 611             .borrow_mut()
 612             .type_dependent_defs_mut()
 613             .remove(hir_id)
 614         {
 615             self.tables.type_dependent_defs_mut().insert(hir_id, def);
 616         }
 617
 618         // Resolve any borrowings for the node with id `node_id`
 619         self.visit_adjustments(span, hir_id);
 620
 621         // Resolve the type of the node with id `node_id`
 622         let n_ty = self.fcx.node_ty(hir_id);
 623         let n_ty = self.resolve(&n_ty, &span);
 624         self.write_ty_to_tables(hir_id, n_ty);
 625         debug!("Node {:?} has type {:?}", hir_id, n_ty);
 626
 627         // Resolve any substitutions
 628         if let Some(substs) = self.fcx.tables.borrow().node_substs_opt(hir_id) {
 629             let substs = self.resolve(&substs, &span);
 630             debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
 631             assert!(!substs.needs_infer() && !substs.has_placeholders());
 632             self.tables.node_substs_mut().insert(hir_id, substs);
 633         }
 634     }
 635
 636     fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 637         let adjustment = self.fcx
 638             .tables
 639             .borrow_mut()
 640             .adjustments_mut()
 641             .remove(hir_id);
 642         match adjustment {
 643             None => {
 644                 debug!("No adjustments for node {:?}", hir_id);
 645             }
 646
 647             Some(adjustment) => {
 648                 let resolved_adjustment = self.resolve(&adjustment, &span);
 649                 debug!(
 650                     "Adjustments for node {:?}: {:?}",
 651                     hir_id, resolved_adjustment
 652                 );
 653                 self.tables
 654                     .adjustments_mut()
 655                     .insert(hir_id, resolved_adjustment);
 656             }
 657         }
 658     }
 659
 660     fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 661         let adjustment = self.fcx
 662             .tables
 663             .borrow_mut()
 664             .pat_adjustments_mut()
 665             .remove(hir_id);
 666         match adjustment {
 667             None => {
 668                 debug!("No pat_adjustments for node {:?}", hir_id);
 669             }
 670
 671             Some(adjustment) => {
 672                 let resolved_adjustment = self.resolve(&adjustment, &span);
 673                 debug!(
 674                     "pat_adjustments for node {:?}: {:?}",
 675                     hir_id, resolved_adjustment
 676                 );
 677                 self.tables
 678                     .pat_adjustments_mut()
 679                     .insert(hir_id, resolved_adjustment);
 680             }
 681         }
 682     }
 683
 684     fn visit_liberated_fn_sigs(&mut self) {
 685         let fcx_tables = self.fcx.tables.borrow();
 686         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 687         let common_local_id_root = fcx_tables.local_id_root.unwrap();
 688
 689         for (&local_id, fn_sig) in fcx_tables.liberated_fn_sigs().iter() {
 690             let hir_id = hir::HirId {
 691                 owner: common_local_id_root.index,
 692                 local_id,
 693             };
 694             let fn_sig = self.resolve(fn_sig, &hir_id);
 695             self.tables
 696                 .liberated_fn_sigs_mut()
 697                 .insert(hir_id, fn_sig.clone());
 698         }
 699     }
 700
 701     fn visit_fru_field_types(&mut self) {
 702         let fcx_tables = self.fcx.tables.borrow();
 703         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 704         let common_local_id_root = fcx_tables.local_id_root.unwrap();
 705
 706         for (&local_id, ftys) in fcx_tables.fru_field_types().iter() {
 707             let hir_id = hir::HirId {
 708                 owner: common_local_id_root.index,
 709                 local_id,
 710             };
 711             let ftys = self.resolve(ftys, &hir_id);
 712             self.tables.fru_field_types_mut().insert(hir_id, ftys);
 713         }
 714     }
 715
 716     fn resolve<T>(&self, x: &T, span: &dyn Locatable) -> T::Lifted
 717     where
 718         T: TypeFoldable<'tcx> + ty::Lift<'gcx>,
 719     {
 720         let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
 721         if let Some(lifted) = self.tcx().lift_to_global(&x) {
 722             lifted
 723         } else {
 724             span_bug!(
 725                 span.to_span(&self.fcx.tcx),
 726                 "writeback: `{:?}` missing from the global type context",
 727                 x
 728             );
 729         }
 730     }
 731 }
 732
 733 trait Locatable {
 734     fn to_span(&self, tcx: &TyCtxt<'_, '_, '_>) -> Span;
 735 }
 736
 737 impl Locatable for Span {
 738     fn to_span(&self, _: &TyCtxt<'_, '_, '_>) -> Span {
 739         *self
 740     }
 741 }
 742
 743 impl Locatable for DefIndex {
 744     fn to_span(&self, tcx: &TyCtxt<'_, '_, '_>) -> Span {
 745         let hir_id = tcx.hir().def_index_to_hir_id(*self);
 746         tcx.hir().span_by_hir_id(hir_id)
 747     }
 748 }
 749
 750 impl Locatable for hir::HirId {
 751     fn to_span(&self, tcx: &TyCtxt<'_, '_, '_>) -> Span {
 752         tcx.hir().span_by_hir_id(*self)
 753     }
 754 }
 755
 756 ///////////////////////////////////////////////////////////////////////////
 757 // The Resolver. This is the type folding engine that detects
 758 // unresolved types and so forth.
 759
 760 struct Resolver<'cx, 'gcx: 'cx + 'tcx, 'tcx: 'cx> {
 761     tcx: TyCtxt<'cx, 'gcx, 'tcx>,
 762     infcx: &'cx InferCtxt<'cx, 'gcx, 'tcx>,
 763     span: &'cx dyn Locatable,
 764     body: &'gcx hir::Body,
 765 }
 766
 767 impl<'cx, 'gcx, 'tcx> Resolver<'cx, 'gcx, 'tcx> {
 768     fn new(
 769         fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
 770         span: &'cx dyn Locatable,
 771         body: &'gcx hir::Body,
 772     ) -> Resolver<'cx, 'gcx, 'tcx> {
 773         Resolver {
 774             tcx: fcx.tcx,
 775             infcx: fcx,
 776             span,
 777             body,
 778         }
 779     }
 780
 781     fn report_error(&self, t: Ty<'tcx>) {
 782         if !self.tcx.sess.has_errors() {
 783             self.infcx
 784                 .need_type_info_err(Some(self.body.id()), self.span.to_span(&self.tcx), t)
 785                 .emit();
 786         }
 787     }
 788 }
 789
 790 impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for Resolver<'cx, 'gcx, 'tcx> {
 791     fn tcx<'a>(&'a self) -> TyCtxt<'a, 'gcx, 'tcx> {
 792         self.tcx
 793     }
 794
 795     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
 796         match self.infcx.fully_resolve(&t) {
 797             Ok(t) => t,
 798             Err(_) => {
 799                 debug!(
 800                     "Resolver::fold_ty: input type `{:?}` not fully resolvable",
 801                     t
 802                 );
 803                 self.report_error(t);
 804                 self.tcx().types.err
 805             }
 806         }
 807     }
 808
 809     // FIXME This should be carefully checked
 810     // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
 811     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
 812         self.infcx.fully_resolve(&r).unwrap_or(self.tcx.types.re_static)
 813     }
 814 }
 815
 816 ///////////////////////////////////////////////////////////////////////////
 817 // During type check, we store promises with the result of trait
 818 // lookup rather than the actual results (because the results are not
 819 // necessarily available immediately). These routines unwind the
 820 // promises. It is expected that we will have already reported any
 821 // errors that may be encountered, so if the promises store an error,
 822 // a dummy result is returned.