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::mir::interpret::ConstValue;
  16 use rustc::util::nodemap::DefIdSet;
  17 use rustc_data_structures::sync::Lrc;
  18 use std::mem;
  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         // Type only exists for constants and statics, not functions.
  47         match self.tcx.hir().body_owner_kind(item_id) {
  48             hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => {
  49                 let item_hir_id = self.tcx.hir().node_to_hir_id(item_id);
  50                 wbcx.visit_node_id(body.value.span, item_hir_id);
  51             }
  52             hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => (),
  53         }
  54         wbcx.visit_body(body);
  55         wbcx.visit_upvar_capture_map();
  56         wbcx.visit_upvar_list_map();
  57         wbcx.visit_closures();
  58         wbcx.visit_liberated_fn_sigs();
  59         wbcx.visit_fru_field_types();
  60         wbcx.visit_opaque_types(body.value.span);
  61         wbcx.visit_coercion_casts();
  62         wbcx.visit_free_region_map();
  63         wbcx.visit_user_provided_tys();
  64         wbcx.visit_user_provided_sigs();
  65
  66         let used_trait_imports = mem::replace(
  67             &mut self.tables.borrow_mut().used_trait_imports,
  68             Lrc::new(DefIdSet::default()),
  69         );
  70         debug!(
  71             "used_trait_imports({:?}) = {:?}",
  72             item_def_id, used_trait_imports
  73         );
  74         wbcx.tables.used_trait_imports = used_trait_imports;
  75
  76         wbcx.tables.tainted_by_errors = self.is_tainted_by_errors();
  77
  78         debug!(
  79             "writeback: tables for {:?} are {:#?}",
  80             item_def_id, wbcx.tables
  81         );
  82
  83         self.tcx.alloc_tables(wbcx.tables)
  84     }
  85 }
  86
  87 ///////////////////////////////////////////////////////////////////////////
  88 // The Writeback context. This visitor walks the AST, checking the
  89 // fn-specific tables to find references to types or regions. It
  90 // resolves those regions to remove inference variables and writes the
  91 // final result back into the master tables in the tcx. Here and
  92 // there, it applies a few ad-hoc checks that were not convenient to
  93 // do elsewhere.
  94
  95 struct WritebackCx<'cx, 'gcx: 'cx + 'tcx, 'tcx: 'cx> {
  96     fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
  97
  98     tables: ty::TypeckTables<'gcx>,
  99
 100     body: &'gcx hir::Body,
 101
 102     rustc_dump_user_substs: bool,
 103 }
 104
 105 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
 106     fn new(
 107         fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
 108         body: &'gcx hir::Body,
 109         rustc_dump_user_substs: bool,
 110     ) -> WritebackCx<'cx, 'gcx, 'tcx> {
 111         let owner = body.id().hir_id;
 112
 113         WritebackCx {
 114             fcx,
 115             tables: ty::TypeckTables::empty(Some(DefId::local(owner.owner))),
 116             body,
 117             rustc_dump_user_substs,
 118         }
 119     }
 120
 121     fn tcx(&self) -> TyCtxt<'cx, 'gcx, 'tcx> {
 122         self.fcx.tcx
 123     }
 124
 125     fn write_ty_to_tables(&mut self, hir_id: hir::HirId, ty: Ty<'gcx>) {
 126         debug!("write_ty_to_tables({:?}, {:?})", hir_id, ty);
 127         assert!(!ty.needs_infer() && !ty.has_placeholders());
 128         self.tables.node_types_mut().insert(hir_id, ty);
 129     }
 130
 131     // Hacky hack: During type-checking, we treat *all* operators
 132     // as potentially overloaded. But then, during writeback, if
 133     // we observe that something like `a+b` is (known to be)
 134     // operating on scalars, we clear the overload.
 135     fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr) {
 136         match e.node {
 137             hir::ExprKind::Unary(hir::UnNeg, ref inner)
 138             | hir::ExprKind::Unary(hir::UnNot, ref inner) => {
 139                 let inner_ty = self.fcx.node_ty(inner.hir_id);
 140                 let inner_ty = self.fcx.resolve_type_vars_if_possible(&inner_ty);
 141
 142                 if inner_ty.is_scalar() {
 143                     let mut tables = self.fcx.tables.borrow_mut();
 144                     tables.type_dependent_defs_mut().remove(e.hir_id);
 145                     tables.node_substs_mut().remove(e.hir_id);
 146                 }
 147             }
 148             hir::ExprKind::Binary(ref op, ref lhs, ref rhs)
 149             | hir::ExprKind::AssignOp(ref op, ref lhs, ref rhs) => {
 150                 let lhs_ty = self.fcx.node_ty(lhs.hir_id);
 151                 let lhs_ty = self.fcx.resolve_type_vars_if_possible(&lhs_ty);
 152
 153                 let rhs_ty = self.fcx.node_ty(rhs.hir_id);
 154                 let rhs_ty = self.fcx.resolve_type_vars_if_possible(&rhs_ty);
 155
 156                 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
 157                     let mut tables = self.fcx.tables.borrow_mut();
 158                     tables.type_dependent_defs_mut().remove(e.hir_id);
 159                     tables.node_substs_mut().remove(e.hir_id);
 160
 161                     match e.node {
 162                         hir::ExprKind::Binary(..) => {
 163                             if !op.node.is_by_value() {
 164                                 let mut adjustments = tables.adjustments_mut();
 165                                 adjustments.get_mut(lhs.hir_id).map(|a| a.pop());
 166                                 adjustments.get_mut(rhs.hir_id).map(|a| a.pop());
 167                             }
 168                         }
 169                         hir::ExprKind::AssignOp(..) => {
 170                             tables
 171                                 .adjustments_mut()
 172                                 .get_mut(lhs.hir_id)
 173                                 .map(|a| a.pop());
 174                         }
 175                         _ => {}
 176                     }
 177                 }
 178             }
 179             _ => {}
 180         }
 181     }
 182
 183     // Similar to operators, indexing is always assumed to be overloaded
 184     // Here, correct cases where an indexing expression can be simplified
 185     // to use builtin indexing because the index type is known to be
 186     // usize-ish
 187     fn fix_index_builtin_expr(&mut self, e: &hir::Expr) {
 188         if let hir::ExprKind::Index(ref base, ref index) = e.node {
 189             let mut tables = self.fcx.tables.borrow_mut();
 190
 191             // All valid indexing looks like this; might encounter non-valid indexes at this point
 192             if let ty::Ref(_, base_ty, _) = tables.expr_ty_adjusted(&base).sty {
 193                 let index_ty = tables.expr_ty_adjusted(&index);
 194                 let index_ty = self.fcx.resolve_type_vars_if_possible(&index_ty);
 195
 196                 if base_ty.builtin_index().is_some() && index_ty == self.fcx.tcx.types.usize {
 197                     // Remove the method call record
 198                     tables.type_dependent_defs_mut().remove(e.hir_id);
 199                     tables.node_substs_mut().remove(e.hir_id);
 200
 201                     tables.adjustments_mut().get_mut(base.hir_id).map(|a| {
 202                         // Discard the need for a mutable borrow
 203                         match a.pop() {
 204                             // Extra adjustment made when indexing causes a drop
 205                             // of size information - we need to get rid of it
 206                             // Since this is "after" the other adjustment to be
 207                             // discarded, we do an extra `pop()`
 208                             Some(Adjustment {
 209                                 kind: Adjust::Pointer(PointerCast::Unsize),
 210                                 ..
 211                             }) => {
 212                                 // So the borrow discard actually happens here
 213                                 a.pop();
 214                             }
 215                             _ => {}
 216                         }
 217                     });
 218                 }
 219             }
 220         }
 221     }
 222 }
 223
 224 ///////////////////////////////////////////////////////////////////////////
 225 // Impl of Visitor for Resolver
 226 //
 227 // This is the master code which walks the AST. It delegates most of
 228 // the heavy lifting to the generic visit and resolve functions
 229 // below. In general, a function is made into a `visitor` if it must
 230 // traffic in node-ids or update tables in the type context etc.
 231
 232 impl<'cx, 'gcx, 'tcx> Visitor<'gcx> for WritebackCx<'cx, 'gcx, 'tcx> {
 233     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
 234         NestedVisitorMap::None
 235     }
 236
 237     fn visit_expr(&mut self, e: &'gcx hir::Expr) {
 238         self.fix_scalar_builtin_expr(e);
 239         self.fix_index_builtin_expr(e);
 240
 241         self.visit_node_id(e.span, e.hir_id);
 242
 243         match e.node {
 244             hir::ExprKind::Closure(_, _, body, _, _) => {
 245                 let body = self.fcx.tcx.hir().body(body);
 246                 for arg in &body.arguments {
 247                     self.visit_node_id(e.span, arg.hir_id);
 248                 }
 249
 250                 self.visit_body(body);
 251             }
 252             hir::ExprKind::Struct(_, ref fields, _) => {
 253                 for field in fields {
 254                     self.visit_field_id(field.hir_id);
 255                 }
 256             }
 257             hir::ExprKind::Field(..) => {
 258                 self.visit_field_id(e.hir_id);
 259             }
 260             _ => {}
 261         }
 262
 263         intravisit::walk_expr(self, e);
 264     }
 265
 266     fn visit_block(&mut self, b: &'gcx hir::Block) {
 267         self.visit_node_id(b.span, b.hir_id);
 268         intravisit::walk_block(self, b);
 269     }
 270
 271     fn visit_pat(&mut self, p: &'gcx hir::Pat) {
 272         match p.node {
 273             hir::PatKind::Binding(..) => {
 274                 if let Some(&bm) = self.fcx.tables.borrow().pat_binding_modes().get(p.hir_id) {
 275                     self.tables.pat_binding_modes_mut().insert(p.hir_id, bm);
 276                 } else {
 277                     self.tcx()
 278                         .sess
 279                         .delay_span_bug(p.span, "missing binding mode");
 280                 }
 281             }
 282             hir::PatKind::Struct(_, ref fields, _) => {
 283                 for field in fields {
 284                     self.visit_field_id(field.node.hir_id);
 285                 }
 286             }
 287             _ => {}
 288         };
 289
 290         self.visit_pat_adjustments(p.span, p.hir_id);
 291
 292         self.visit_node_id(p.span, p.hir_id);
 293         intravisit::walk_pat(self, p);
 294     }
 295
 296     fn visit_local(&mut self, l: &'gcx hir::Local) {
 297         intravisit::walk_local(self, l);
 298         let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
 299         let var_ty = self.resolve(&var_ty, &l.span);
 300         self.write_ty_to_tables(l.hir_id, var_ty);
 301     }
 302
 303     fn visit_ty(&mut self, hir_ty: &'gcx hir::Ty) {
 304         intravisit::walk_ty(self, hir_ty);
 305         let ty = self.fcx.node_ty(hir_ty.hir_id);
 306         let ty = self.resolve(&ty, &hir_ty.span);
 307         self.write_ty_to_tables(hir_ty.hir_id, ty);
 308     }
 309
 310     fn visit_argument_source(&mut self, s: &'gcx hir::ArgSource) {
 311         match s {
 312             // Don't visit the pattern in `ArgSource::AsyncFn`, it contains a pattern which has
 313             // a `NodeId` w/out a type, as it is only used for getting the name of the original
 314             // pattern for diagnostics where only an `hir::Arg` is present.
 315             hir::ArgSource::AsyncFn(..) => {},
 316             _ => intravisit::walk_argument_source(self, s),
 317         }
 318     }
 319 }
 320
 321 impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
 322     fn visit_upvar_capture_map(&mut self) {
 323         for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
 324             let new_upvar_capture = match *upvar_capture {
 325                 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
 326                 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
 327                     let r = upvar_borrow.region;
 328                     let r = self.resolve(&r, &upvar_id.var_path.hir_id);
 329                     ty::UpvarCapture::ByRef(ty::UpvarBorrow {
 330                         kind: upvar_borrow.kind,
 331                         region: r,
 332                     })
 333                 }
 334             };
 335             debug!(
 336                 "Upvar capture for {:?} resolved to {:?}",
 337                 upvar_id, new_upvar_capture
 338             );
 339             self.tables
 340                 .upvar_capture_map
 341                 .insert(*upvar_id, new_upvar_capture);
 342         }
 343     }
 344
 345     /// Runs through the function context's upvar list map and adds the same to
 346     /// the TypeckTables. upvarlist is a hashmap of the list of upvars referred
 347     /// to in a closure..
 348     fn visit_upvar_list_map(&mut self) {
 349         for (closure_def_id, upvar_list) in self.fcx.tables.borrow().upvar_list.iter() {
 350             debug!(
 351                 "UpvarIDs captured by closure {:?} are: {:?}",
 352                 closure_def_id, upvar_list
 353             );
 354             self.tables
 355                 .upvar_list
 356                 .insert(*closure_def_id, upvar_list.to_vec());
 357         }
 358     }
 359
 360     fn visit_closures(&mut self) {
 361         let fcx_tables = self.fcx.tables.borrow();
 362         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 363         let common_local_id_root = fcx_tables.local_id_root.unwrap();
 364
 365         for (&id, &origin) in fcx_tables.closure_kind_origins().iter() {
 366             let hir_id = hir::HirId {
 367                 owner: common_local_id_root.index,
 368                 local_id: id,
 369             };
 370             self.tables
 371                 .closure_kind_origins_mut()
 372                 .insert(hir_id, origin);
 373         }
 374     }
 375
 376     fn visit_coercion_casts(&mut self) {
 377         let fcx_tables = self.fcx.tables.borrow();
 378         let fcx_coercion_casts = fcx_tables.coercion_casts();
 379         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 380
 381         for local_id in fcx_coercion_casts {
 382             self.tables.set_coercion_cast(*local_id);
 383         }
 384     }
 385
 386     fn visit_free_region_map(&mut self) {
 387         let free_region_map = self.tcx()
 388             .lift_to_global(&self.fcx.tables.borrow().free_region_map);
 389         let free_region_map = free_region_map.expect("all regions in free-region-map are global");
 390         self.tables.free_region_map = free_region_map;
 391     }
 392
 393     fn visit_user_provided_tys(&mut self) {
 394         let fcx_tables = self.fcx.tables.borrow();
 395         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 396         let common_local_id_root = fcx_tables.local_id_root.unwrap();
 397
 398         let mut errors_buffer = Vec::new();
 399         for (&local_id, c_ty) in fcx_tables.user_provided_types().iter() {
 400             let hir_id = hir::HirId {
 401                 owner: common_local_id_root.index,
 402                 local_id,
 403             };
 404
 405             let c_ty = if let Some(c_ty) = self.tcx().lift_to_global(c_ty) {
 406                 c_ty
 407             } else {
 408                 span_bug!(
 409                     hir_id.to_span(self.fcx.tcx),
 410                     "writeback: `{:?}` missing from the global type context",
 411                     c_ty
 412                 );
 413             };
 414
 415             self.tables
 416                 .user_provided_types_mut()
 417                 .insert(hir_id, c_ty.clone());
 418
 419             if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
 420                 if self.rustc_dump_user_substs {
 421                     // This is a unit-testing mechanism.
 422                     let span = self.tcx().hir().span_by_hir_id(hir_id);
 423                     // We need to buffer the errors in order to guarantee a consistent
 424                     // order when emitting them.
 425                     let err = self.tcx().sess.struct_span_err(
 426                         span,
 427                         &format!("user substs: {:?}", user_substs)
 428                     );
 429                     err.buffer(&mut errors_buffer);
 430                 }
 431             }
 432         }
 433
 434         if !errors_buffer.is_empty() {
 435             errors_buffer.sort_by_key(|diag| diag.span.primary_span());
 436             for diag in errors_buffer.drain(..) {
 437                 DiagnosticBuilder::new_diagnostic(self.tcx().sess.diagnostic(), diag).emit();
 438             }
 439         }
 440     }
 441
 442     fn visit_user_provided_sigs(&mut self) {
 443         let fcx_tables = self.fcx.tables.borrow();
 444         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 445
 446         for (&def_id, c_sig) in fcx_tables.user_provided_sigs.iter() {
 447             let c_sig = if let Some(c_sig) = self.tcx().lift_to_global(c_sig) {
 448                 c_sig
 449             } else {
 450                 span_bug!(
 451                     self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
 452                     "writeback: `{:?}` missing from the global type context",
 453                     c_sig
 454                 );
 455             };
 456
 457             self.tables
 458                 .user_provided_sigs
 459                 .insert(def_id, c_sig.clone());
 460         }
 461     }
 462
 463     fn visit_opaque_types(&mut self, span: Span) {
 464         for (&def_id, opaque_defn) in self.fcx.opaque_types.borrow().iter() {
 465             let hir_id = self.tcx().hir().as_local_hir_id(def_id).unwrap();
 466             let instantiated_ty = self.resolve(&opaque_defn.concrete_ty, &hir_id);
 467
 468             let generics = self.tcx().generics_of(def_id);
 469
 470             let definition_ty = if generics.parent.is_some() {
 471                 // impl trait
 472                 self.fcx.infer_opaque_definition_from_instantiation(
 473                     def_id,
 474                     opaque_defn,
 475                     instantiated_ty,
 476                 )
 477             } else {
 478                 // prevent
 479                 // * `fn foo<T>() -> Foo<T>`
 480                 // * `fn foo<T: Bound + Other>() -> Foo<T>`
 481                 // from being defining
 482
 483                 // Also replace all generic params with the ones from the existential type
 484                 // definition so
 485                 // ```rust
 486                 // existential type Foo<T>: 'static;
 487                 // fn foo<U>() -> Foo<U> { .. }
 488                 // ```
 489                 // figures out the concrete type with `U`, but the stored type is with `T`
 490                 instantiated_ty.fold_with(&mut BottomUpFolder {
 491                     tcx: self.tcx().global_tcx(),
 492                     ty_op: |ty| {
 493                         trace!("checking type {:?}", ty);
 494                         // find a type parameter
 495                         if let ty::Param(..) = ty.sty {
 496                             // look it up in the substitution list
 497                             assert_eq!(opaque_defn.substs.len(), generics.params.len());
 498                             for (subst, param) in opaque_defn.substs.iter().zip(&generics.params) {
 499                                 if let UnpackedKind::Type(subst) = subst.unpack() {
 500                                     if subst == ty {
 501                                         // found it in the substitution list, replace with the
 502                                         // parameter from the existential type
 503                                         return self.tcx()
 504                                             .global_tcx()
 505                                             .mk_ty_param(param.index, param.name);
 506                                     }
 507                                 }
 508                             }
 509                             self.tcx()
 510                                 .sess
 511                                 .struct_span_err(
 512                                     span,
 513                                     &format!(
 514                                         "type parameter `{}` is part of concrete type but not used \
 515                                          in parameter list for existential type",
 516                                         ty,
 517                                     ),
 518                                 )
 519                                 .emit();
 520                             return self.tcx().types.err;
 521                         }
 522                         ty
 523                     },
 524                     lt_op: |region| {
 525                         match region {
 526                             // ignore static regions
 527                             ty::ReStatic => region,
 528                             _ => {
 529                                 trace!("checking {:?}", region);
 530                                 for (subst, p) in opaque_defn.substs.iter().zip(&generics.params) {
 531                                     if let UnpackedKind::Lifetime(subst) = subst.unpack() {
 532                                         if subst == region {
 533                                             // found it in the substitution list, replace with the
 534                                             // parameter from the existential type
 535                                             let reg = ty::EarlyBoundRegion {
 536                                                 def_id: p.def_id,
 537                                                 index: p.index,
 538                                                 name: p.name,
 539                                             };
 540                                             trace!("replace {:?} with {:?}", region, reg);
 541                                             return self.tcx()
 542                                                 .global_tcx()
 543                                                 .mk_region(ty::ReEarlyBound(reg));
 544                                         }
 545                                     }
 546                                 }
 547                                 trace!("opaque_defn: {:#?}", opaque_defn);
 548                                 trace!("generics: {:#?}", generics);
 549                                 self.tcx()
 550                                     .sess
 551                                     .struct_span_err(
 552                                         span,
 553                                         "non-defining existential type use in defining scope",
 554                                     )
 555                                     .span_label(
 556                                         span,
 557                                         format!(
 558                                             "lifetime `{}` is part of concrete type but not used \
 559                                              in parameter list of existential type",
 560                                             region,
 561                                         ),
 562                                     )
 563                                     .emit();
 564                                 self.tcx().global_tcx().mk_region(ty::ReStatic)
 565                             }
 566                         }
 567                     },
 568                     ct_op: |ct| {
 569                         trace!("checking const {:?}", ct);
 570                         // Find a const parameter
 571                         if let ConstValue::Param(..) = ct.val {
 572                             // look it up in the substitution list
 573                             assert_eq!(opaque_defn.substs.len(), generics.params.len());
 574                             for (subst, param) in opaque_defn.substs.iter()
 575                                                                     .zip(&generics.params) {
 576                                 if let UnpackedKind::Const(subst) = subst.unpack() {
 577                                     if subst == ct {
 578                                         // found it in the substitution list, replace with the
 579                                         // parameter from the existential type
 580                                         return self.tcx()
 581                                             .global_tcx()
 582                                             .mk_const_param(param.index, param.name, ct.ty);
 583                                     }
 584                                 }
 585                             }
 586                             self.tcx()
 587                                 .sess
 588                                 .struct_span_err(
 589                                     span,
 590                                     &format!(
 591                                         "const parameter `{}` is part of concrete type but not \
 592                                             used in parameter list for existential type",
 593                                         ct,
 594                                     ),
 595                                 )
 596                                 .emit();
 597                             return self.tcx().consts.err;
 598                         }
 599                         ct
 600                     }
 601                 })
 602             };
 603
 604             if let ty::Opaque(defin_ty_def_id, _substs) = definition_ty.sty {
 605                 if def_id == defin_ty_def_id {
 606                     // Concrete type resolved to the existential type itself
 607                     // Force a cycle error
 608                     // FIXME(oli-obk): we could just not insert it into `concrete_existential_types`
 609                     // which simply would make this use not a defining use.
 610                     self.tcx().at(span).type_of(defin_ty_def_id);
 611                 }
 612             }
 613
 614             let new = ty::ResolvedOpaqueTy {
 615                 concrete_type: definition_ty,
 616                 substs: self.tcx().lift_to_global(&opaque_defn.substs).unwrap(),
 617             };
 618
 619             let old = self.tables
 620                 .concrete_existential_types
 621                 .insert(def_id, new);
 622             if let Some(old) = old {
 623                 if old.concrete_type != definition_ty || old.substs != opaque_defn.substs {
 624                     span_bug!(
 625                         span,
 626                         "visit_opaque_types tried to write \
 627                         different types for the same existential type: {:?}, {:?}, {:?}, {:?}",
 628                         def_id,
 629                         definition_ty,
 630                         opaque_defn,
 631                         old,
 632                     );
 633                 }
 634             }
 635         }
 636     }
 637
 638     fn visit_field_id(&mut self, hir_id: hir::HirId) {
 639         if let Some(index) = self.fcx
 640             .tables
 641             .borrow_mut()
 642             .field_indices_mut()
 643             .remove(hir_id)
 644         {
 645             self.tables.field_indices_mut().insert(hir_id, index);
 646         }
 647     }
 648
 649     fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
 650         // Export associated path extensions and method resolutions.
 651         if let Some(def) = self.fcx
 652             .tables
 653             .borrow_mut()
 654             .type_dependent_defs_mut()
 655             .remove(hir_id)
 656         {
 657             self.tables.type_dependent_defs_mut().insert(hir_id, def);
 658         }
 659
 660         // Resolve any borrowings for the node with id `node_id`
 661         self.visit_adjustments(span, hir_id);
 662
 663         // Resolve the type of the node with id `node_id`
 664         let n_ty = self.fcx.node_ty(hir_id);
 665         let n_ty = self.resolve(&n_ty, &span);
 666         self.write_ty_to_tables(hir_id, n_ty);
 667         debug!("Node {:?} has type {:?}", hir_id, n_ty);
 668
 669         // Resolve any substitutions
 670         if let Some(substs) = self.fcx.tables.borrow().node_substs_opt(hir_id) {
 671             let substs = self.resolve(&substs, &span);
 672             debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
 673             assert!(!substs.needs_infer() && !substs.has_placeholders());
 674             self.tables.node_substs_mut().insert(hir_id, substs);
 675         }
 676     }
 677
 678     fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 679         let adjustment = self.fcx
 680             .tables
 681             .borrow_mut()
 682             .adjustments_mut()
 683             .remove(hir_id);
 684         match adjustment {
 685             None => {
 686                 debug!("No adjustments for node {:?}", hir_id);
 687             }
 688
 689             Some(adjustment) => {
 690                 let resolved_adjustment = self.resolve(&adjustment, &span);
 691                 debug!(
 692                     "Adjustments for node {:?}: {:?}",
 693                     hir_id, resolved_adjustment
 694                 );
 695                 self.tables
 696                     .adjustments_mut()
 697                     .insert(hir_id, resolved_adjustment);
 698             }
 699         }
 700     }
 701
 702     fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
 703         let adjustment = self.fcx
 704             .tables
 705             .borrow_mut()
 706             .pat_adjustments_mut()
 707             .remove(hir_id);
 708         match adjustment {
 709             None => {
 710                 debug!("No pat_adjustments for node {:?}", hir_id);
 711             }
 712
 713             Some(adjustment) => {
 714                 let resolved_adjustment = self.resolve(&adjustment, &span);
 715                 debug!(
 716                     "pat_adjustments for node {:?}: {:?}",
 717                     hir_id, resolved_adjustment
 718                 );
 719                 self.tables
 720                     .pat_adjustments_mut()
 721                     .insert(hir_id, resolved_adjustment);
 722             }
 723         }
 724     }
 725
 726     fn visit_liberated_fn_sigs(&mut self) {
 727         let fcx_tables = self.fcx.tables.borrow();
 728         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 729         let common_local_id_root = fcx_tables.local_id_root.unwrap();
 730
 731         for (&local_id, fn_sig) in fcx_tables.liberated_fn_sigs().iter() {
 732             let hir_id = hir::HirId {
 733                 owner: common_local_id_root.index,
 734                 local_id,
 735             };
 736             let fn_sig = self.resolve(fn_sig, &hir_id);
 737             self.tables
 738                 .liberated_fn_sigs_mut()
 739                 .insert(hir_id, fn_sig.clone());
 740         }
 741     }
 742
 743     fn visit_fru_field_types(&mut self) {
 744         let fcx_tables = self.fcx.tables.borrow();
 745         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
 746         let common_local_id_root = fcx_tables.local_id_root.unwrap();
 747
 748         for (&local_id, ftys) in fcx_tables.fru_field_types().iter() {
 749             let hir_id = hir::HirId {
 750                 owner: common_local_id_root.index,
 751                 local_id,
 752             };
 753             let ftys = self.resolve(ftys, &hir_id);
 754             self.tables.fru_field_types_mut().insert(hir_id, ftys);
 755         }
 756     }
 757
 758     fn resolve<T>(&self, x: &T, span: &dyn Locatable) -> T::Lifted
 759     where
 760         T: TypeFoldable<'tcx> + ty::Lift<'gcx>,
 761     {
 762         let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
 763         if let Some(lifted) = self.tcx().lift_to_global(&x) {
 764             lifted
 765         } else {
 766             span_bug!(
 767                 span.to_span(self.fcx.tcx),
 768                 "writeback: `{:?}` missing from the global type context",
 769                 x
 770             );
 771         }
 772     }
 773 }
 774
 775 trait Locatable {
 776     fn to_span(&self, tcx: TyCtxt<'_, '_, '_>) -> Span;
 777 }
 778
 779 impl Locatable for Span {
 780     fn to_span(&self, _: TyCtxt<'_, '_, '_>) -> Span {
 781         *self
 782     }
 783 }
 784
 785 impl Locatable for DefIndex {
 786     fn to_span(&self, tcx: TyCtxt<'_, '_, '_>) -> Span {
 787         let hir_id = tcx.hir().def_index_to_hir_id(*self);
 788         tcx.hir().span_by_hir_id(hir_id)
 789     }
 790 }
 791
 792 impl Locatable for hir::HirId {
 793     fn to_span(&self, tcx: TyCtxt<'_, '_, '_>) -> Span {
 794         tcx.hir().span_by_hir_id(*self)
 795     }
 796 }
 797
 798 ///////////////////////////////////////////////////////////////////////////
 799 // The Resolver. This is the type folding engine that detects
 800 // unresolved types and so forth.
 801
 802 struct Resolver<'cx, 'gcx: 'cx + 'tcx, 'tcx: 'cx> {
 803     tcx: TyCtxt<'cx, 'gcx, 'tcx>,
 804     infcx: &'cx InferCtxt<'cx, 'gcx, 'tcx>,
 805     span: &'cx dyn Locatable,
 806     body: &'gcx hir::Body,
 807 }
 808
 809 impl<'cx, 'gcx, 'tcx> Resolver<'cx, 'gcx, 'tcx> {
 810     fn new(
 811         fcx: &'cx FnCtxt<'cx, 'gcx, 'tcx>,
 812         span: &'cx dyn Locatable,
 813         body: &'gcx hir::Body,
 814     ) -> Resolver<'cx, 'gcx, 'tcx> {
 815         Resolver {
 816             tcx: fcx.tcx,
 817             infcx: fcx,
 818             span,
 819             body,
 820         }
 821     }
 822
 823     fn report_error(&self, t: Ty<'tcx>) {
 824         if !self.tcx.sess.has_errors() {
 825             self.infcx
 826                 .need_type_info_err(Some(self.body.id()), self.span.to_span(self.tcx), t)
 827                 .emit();
 828         }
 829     }
 830 }
 831
 832 impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for Resolver<'cx, 'gcx, 'tcx> {
 833     fn tcx<'a>(&'a self) -> TyCtxt<'a, 'gcx, 'tcx> {
 834         self.tcx
 835     }
 836
 837     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
 838         match self.infcx.fully_resolve(&t) {
 839             Ok(t) => t,
 840             Err(_) => {
 841                 debug!(
 842                     "Resolver::fold_ty: input type `{:?}` not fully resolvable",
 843                     t
 844                 );
 845                 self.report_error(t);
 846                 self.tcx().types.err
 847             }
 848         }
 849     }
 850
 851     // FIXME This should be carefully checked
 852     // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
 853     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
 854         self.infcx.fully_resolve(&r).unwrap_or(self.tcx.lifetimes.re_static)
 855     }
 856
 857     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
 858         match self.infcx.fully_resolve(&ct) {
 859             Ok(ct) => ct,
 860             Err(_) => {
 861                 debug!(
 862                     "Resolver::fold_const: input const `{:?}` not fully resolvable",
 863                     ct
 864                 );
 865                 // FIXME: we'd like to use `self.report_error`, but it doesn't yet
 866                 // accept a &'tcx ty::Const.
 867                 self.tcx().consts.err
 868             }
 869         }
 870     }
 871 }
 872
 873 ///////////////////////////////////////////////////////////////////////////
 874 // During type check, we store promises with the result of trait
 875 // lookup rather than the actual results (because the results are not
 876 // necessarily available immediately). These routines unwind the
 877 // promises. It is expected that we will have already reported any
 878 // errors that may be encountered, so if the promises store an error,
 879 // a dummy result is returned.