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