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
6 use hir::def_id::LocalDefId;
7 use rustc_data_structures::fx::FxHashMap;
8 use rustc_errors::ErrorGuaranteed;
10 use rustc_hir::intravisit::{self, Visitor};
11 use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
12 use rustc_infer::infer::InferCtxt;
13 use rustc_middle::hir::place::Place as HirPlace;
14 use rustc_middle::mir::FakeReadCause;
15 use rustc_middle::ty::adjustment::{Adjust, Adjustment, PointerCast};
16 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
17 use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable};
18 use rustc_middle::ty::TypeckResults;
19 use rustc_middle::ty::{self, ClosureSizeProfileData, Ty, TyCtxt};
20 use rustc_span::symbol::sym;
24 use std::ops::ControlFlow;
26 ///////////////////////////////////////////////////////////////////////////
29 // During type inference, partially inferred types are
30 // represented using Type variables (ty::Infer). These don't appear in
31 // the final TypeckResults since all of the types should have been
32 // inferred once typeck is done.
33 // When type inference is running however, having to update the typeck
34 // typeck results every time a new type is inferred would be unreasonably slow,
35 // so instead all of the replacement happens at the end in
36 // resolve_type_vars_in_body, which creates a new TypeTables which
37 // doesn't contain any inference types.
38 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
39 pub fn resolve_type_vars_in_body(
41 body: &'tcx hir::Body<'tcx>,
42 ) -> &'tcx ty::TypeckResults<'tcx> {
43 let item_id = self.tcx.hir().body_owner(body.id());
44 let item_def_id = self.tcx.hir().local_def_id(item_id);
46 // This attribute causes us to dump some writeback information
47 // in the form of errors, which is used for unit tests.
48 let rustc_dump_user_substs =
49 self.tcx.has_attr(item_def_id.to_def_id(), sym::rustc_dump_user_substs);
51 let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_substs);
52 for param in body.params {
53 wbcx.visit_node_id(param.pat.span, param.hir_id);
55 // Type only exists for constants and statics, not functions.
56 match self.tcx.hir().body_owner_kind(item_def_id) {
57 hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => {
58 wbcx.visit_node_id(body.value.span, item_id);
60 hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => (),
62 wbcx.visit_body(body);
63 wbcx.visit_min_capture_map();
64 wbcx.eval_closure_size();
65 wbcx.visit_fake_reads_map();
66 wbcx.visit_closures();
67 wbcx.visit_liberated_fn_sigs();
68 wbcx.visit_fru_field_types();
69 wbcx.visit_opaque_types();
70 wbcx.visit_coercion_casts();
71 wbcx.visit_user_provided_tys();
72 wbcx.visit_user_provided_sigs();
73 wbcx.visit_generator_interior_types();
75 wbcx.typeck_results.rvalue_scopes =
76 mem::take(&mut self.typeck_results.borrow_mut().rvalue_scopes);
78 let used_trait_imports =
79 mem::take(&mut self.typeck_results.borrow_mut().used_trait_imports);
80 debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
81 wbcx.typeck_results.used_trait_imports = used_trait_imports;
83 wbcx.typeck_results.treat_byte_string_as_slice =
84 mem::take(&mut self.typeck_results.borrow_mut().treat_byte_string_as_slice);
86 if let Some(e) = self.is_tainted_by_errors() {
87 wbcx.typeck_results.tainted_by_errors = Some(e);
90 debug!("writeback: typeck results for {:?} are {:#?}", item_def_id, wbcx.typeck_results);
92 self.tcx.arena.alloc(wbcx.typeck_results)
96 ///////////////////////////////////////////////////////////////////////////
97 // The Writeback context. This visitor walks the HIR, checking the
98 // fn-specific typeck results to find references to types or regions. It
99 // resolves those regions to remove inference variables and writes the
100 // final result back into the master typeck results in the tcx. Here and
101 // there, it applies a few ad-hoc checks that were not convenient to
104 struct WritebackCx<'cx, 'tcx> {
105 fcx: &'cx FnCtxt<'cx, 'tcx>,
107 typeck_results: ty::TypeckResults<'tcx>,
109 body: &'tcx hir::Body<'tcx>,
111 rustc_dump_user_substs: bool,
114 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
116 fcx: &'cx FnCtxt<'cx, 'tcx>,
117 body: &'tcx hir::Body<'tcx>,
118 rustc_dump_user_substs: bool,
119 ) -> WritebackCx<'cx, 'tcx> {
120 let owner = body.id().hir_id.owner;
124 typeck_results: ty::TypeckResults::new(owner),
126 rustc_dump_user_substs,
130 fn tcx(&self) -> TyCtxt<'tcx> {
134 fn write_ty_to_typeck_results(&mut self, hir_id: hir::HirId, ty: Ty<'tcx>) {
135 debug!("write_ty_to_typeck_results({:?}, {:?})", hir_id, ty);
136 assert!(!ty.needs_infer() && !ty.has_placeholders() && !ty.has_free_regions());
137 self.typeck_results.node_types_mut().insert(hir_id, ty);
140 // Hacky hack: During type-checking, we treat *all* operators
141 // as potentially overloaded. But then, during writeback, if
142 // we observe that something like `a+b` is (known to be)
143 // operating on scalars, we clear the overload.
144 fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr<'_>) {
146 hir::ExprKind::Unary(hir::UnOp::Neg | hir::UnOp::Not, inner) => {
147 let inner_ty = self.fcx.node_ty(inner.hir_id);
148 let inner_ty = self.fcx.resolve_vars_if_possible(inner_ty);
150 if inner_ty.is_scalar() {
151 let mut typeck_results = self.fcx.typeck_results.borrow_mut();
152 typeck_results.type_dependent_defs_mut().remove(e.hir_id);
153 typeck_results.node_substs_mut().remove(e.hir_id);
156 hir::ExprKind::Binary(ref op, lhs, rhs) | hir::ExprKind::AssignOp(ref op, lhs, rhs) => {
157 let lhs_ty = self.fcx.node_ty(lhs.hir_id);
158 let lhs_ty = self.fcx.resolve_vars_if_possible(lhs_ty);
160 let rhs_ty = self.fcx.node_ty(rhs.hir_id);
161 let rhs_ty = self.fcx.resolve_vars_if_possible(rhs_ty);
163 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
164 let mut typeck_results = self.fcx.typeck_results.borrow_mut();
165 typeck_results.type_dependent_defs_mut().remove(e.hir_id);
166 typeck_results.node_substs_mut().remove(e.hir_id);
169 hir::ExprKind::Binary(..) => {
170 if !op.node.is_by_value() {
171 let mut adjustments = typeck_results.adjustments_mut();
172 if let Some(a) = adjustments.get_mut(lhs.hir_id) {
175 if let Some(a) = adjustments.get_mut(rhs.hir_id) {
180 hir::ExprKind::AssignOp(..)
181 if let Some(a) = typeck_results.adjustments_mut().get_mut(lhs.hir_id) =>
193 // (ouz-a 1005988): Normally `[T] : std::ops::Index<usize>` should be normalized
194 // into [T] but currently `Where` clause stops the normalization process for it,
195 // here we compare types of expr and base in a code without `Where` clause they would be equal
196 // if they are not we don't modify the expr, hence we bypass the ICE
199 typeck_results: &TypeckResults<'tcx>,
204 if let Some(elem_ty) = base_ty.builtin_index() {
205 let Some(exp_ty) = typeck_results.expr_ty_opt(e) else {return false;};
206 let resolved_exp_ty = self.resolve(exp_ty, &e.span);
208 elem_ty == resolved_exp_ty && index_ty == self.fcx.tcx.types.usize
214 // Similar to operators, indexing is always assumed to be overloaded
215 // Here, correct cases where an indexing expression can be simplified
216 // to use builtin indexing because the index type is known to be
218 fn fix_index_builtin_expr(&mut self, e: &hir::Expr<'_>) {
219 if let hir::ExprKind::Index(ref base, ref index) = e.kind {
220 let mut typeck_results = self.fcx.typeck_results.borrow_mut();
222 // All valid indexing looks like this; might encounter non-valid indexes at this point.
223 let base_ty = typeck_results
224 .expr_ty_adjusted_opt(base)
225 .map(|t| self.fcx.resolve_vars_if_possible(t).kind());
226 if base_ty.is_none() {
227 // When encountering `return [0][0]` outside of a `fn` body we can encounter a base
228 // that isn't in the type table. We assume more relevant errors have already been
229 // emitted, so we delay an ICE if none have. (#64638)
230 self.tcx().sess.delay_span_bug(e.span, &format!("bad base: `{:?}`", base));
232 if let Some(ty::Ref(_, base_ty, _)) = base_ty {
233 let index_ty = typeck_results.expr_ty_adjusted_opt(index).unwrap_or_else(|| {
234 // When encountering `return [0][0]` outside of a `fn` body we would attempt
235 // to access an nonexistent index. We assume that more relevant errors will
236 // already have been emitted, so we only gate on this with an ICE if no
237 // error has been emitted. (#64638)
238 self.fcx.tcx.ty_error_with_message(
240 &format!("bad index {:?} for base: `{:?}`", index, base),
243 let index_ty = self.fcx.resolve_vars_if_possible(index_ty);
244 let resolved_base_ty = self.resolve(*base_ty, &base.span);
246 if self.is_builtin_index(&typeck_results, e, resolved_base_ty, index_ty) {
247 // Remove the method call record
248 typeck_results.type_dependent_defs_mut().remove(e.hir_id);
249 typeck_results.node_substs_mut().remove(e.hir_id);
251 if let Some(a) = typeck_results.adjustments_mut().get_mut(base.hir_id) {
252 // Discard the need for a mutable borrow
254 // Extra adjustment made when indexing causes a drop
255 // of size information - we need to get rid of it
256 // Since this is "after" the other adjustment to be
257 // discarded, we do an extra `pop()`
258 if let Some(Adjustment {
259 kind: Adjust::Pointer(PointerCast::Unsize), ..
262 // So the borrow discard actually happens here
272 ///////////////////////////////////////////////////////////////////////////
273 // Impl of Visitor for Resolver
275 // This is the master code which walks the AST. It delegates most of
276 // the heavy lifting to the generic visit and resolve functions
277 // below. In general, a function is made into a `visitor` if it must
278 // traffic in node-ids or update typeck results in the type context etc.
280 impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
281 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
282 self.fix_scalar_builtin_expr(e);
283 self.fix_index_builtin_expr(e);
286 hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
287 let body = self.fcx.tcx.hir().body(body);
288 for param in body.params {
289 self.visit_node_id(e.span, param.hir_id);
292 self.visit_body(body);
294 hir::ExprKind::Struct(_, fields, _) => {
295 for field in fields {
296 self.visit_field_id(field.hir_id);
299 hir::ExprKind::Field(..) => {
300 self.visit_field_id(e.hir_id);
302 hir::ExprKind::ConstBlock(anon_const) => {
303 self.visit_node_id(e.span, anon_const.hir_id);
305 let body = self.tcx().hir().body(anon_const.body);
306 self.visit_body(body);
311 self.visit_node_id(e.span, e.hir_id);
312 intravisit::walk_expr(self, e);
315 fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
317 hir::GenericParamKind::Lifetime { .. } => {
318 // Nothing to write back here
320 hir::GenericParamKind::Type { .. } | hir::GenericParamKind::Const { .. } => {
321 self.tcx().sess.delay_span_bug(p.span, format!("unexpected generic param: {p:?}"));
326 fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
327 self.visit_node_id(b.span, b.hir_id);
328 intravisit::walk_block(self, b);
331 fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
333 hir::PatKind::Binding(..) => {
334 let typeck_results = self.fcx.typeck_results.borrow();
336 typeck_results.extract_binding_mode(self.tcx().sess, p.hir_id, p.span)
338 self.typeck_results.pat_binding_modes_mut().insert(p.hir_id, bm);
341 hir::PatKind::Struct(_, fields, _) => {
342 for field in fields {
343 self.visit_field_id(field.hir_id);
349 self.visit_pat_adjustments(p.span, p.hir_id);
351 self.visit_node_id(p.span, p.hir_id);
352 intravisit::walk_pat(self, p);
355 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
356 intravisit::walk_local(self, l);
357 let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
358 let var_ty = self.resolve(var_ty, &l.span);
359 self.write_ty_to_typeck_results(l.hir_id, var_ty);
362 fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx>) {
363 intravisit::walk_ty(self, hir_ty);
364 let ty = self.fcx.node_ty(hir_ty.hir_id);
365 let ty = self.resolve(ty, &hir_ty.span);
366 self.write_ty_to_typeck_results(hir_ty.hir_id, ty);
369 fn visit_infer(&mut self, inf: &'tcx hir::InferArg) {
370 intravisit::walk_inf(self, inf);
371 // Ignore cases where the inference is a const.
372 if let Some(ty) = self.fcx.node_ty_opt(inf.hir_id) {
373 let ty = self.resolve(ty, &inf.span);
374 self.write_ty_to_typeck_results(inf.hir_id, ty);
379 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
380 fn eval_closure_size(&mut self) {
381 let mut res: FxHashMap<LocalDefId, ClosureSizeProfileData<'tcx>> = Default::default();
382 for (&closure_def_id, data) in self.fcx.typeck_results.borrow().closure_size_eval.iter() {
383 let closure_hir_id = self.tcx().hir().local_def_id_to_hir_id(closure_def_id);
385 let data = self.resolve(*data, &closure_hir_id);
387 res.insert(closure_def_id, data);
390 self.typeck_results.closure_size_eval = res;
392 fn visit_min_capture_map(&mut self) {
393 let mut min_captures_wb = ty::MinCaptureInformationMap::with_capacity_and_hasher(
394 self.fcx.typeck_results.borrow().closure_min_captures.len(),
397 for (&closure_def_id, root_min_captures) in
398 self.fcx.typeck_results.borrow().closure_min_captures.iter()
400 let mut root_var_map_wb = ty::RootVariableMinCaptureList::with_capacity_and_hasher(
401 root_min_captures.len(),
404 for (var_hir_id, min_list) in root_min_captures.iter() {
405 let min_list_wb = min_list
407 .map(|captured_place| {
408 let locatable = captured_place.info.path_expr_id.unwrap_or_else(|| {
409 self.tcx().hir().local_def_id_to_hir_id(closure_def_id)
412 self.resolve(captured_place.clone(), &locatable)
415 root_var_map_wb.insert(*var_hir_id, min_list_wb);
417 min_captures_wb.insert(closure_def_id, root_var_map_wb);
420 self.typeck_results.closure_min_captures = min_captures_wb;
423 fn visit_fake_reads_map(&mut self) {
424 let mut resolved_closure_fake_reads: FxHashMap<
426 Vec<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>,
427 > = Default::default();
428 for (&closure_def_id, fake_reads) in
429 self.fcx.typeck_results.borrow().closure_fake_reads.iter()
431 let mut resolved_fake_reads = Vec::<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>::new();
432 for (place, cause, hir_id) in fake_reads.iter() {
433 let locatable = self.tcx().hir().local_def_id_to_hir_id(closure_def_id);
435 let resolved_fake_read = self.resolve(place.clone(), &locatable);
436 resolved_fake_reads.push((resolved_fake_read, *cause, *hir_id));
438 resolved_closure_fake_reads.insert(closure_def_id, resolved_fake_reads);
440 self.typeck_results.closure_fake_reads = resolved_closure_fake_reads;
443 fn visit_closures(&mut self) {
444 let fcx_typeck_results = self.fcx.typeck_results.borrow();
445 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
446 let common_hir_owner = fcx_typeck_results.hir_owner;
448 for (id, origin) in fcx_typeck_results.closure_kind_origins().iter() {
449 let hir_id = hir::HirId { owner: common_hir_owner, local_id: *id };
450 let place_span = origin.0;
451 let place = self.resolve(origin.1.clone(), &place_span);
452 self.typeck_results.closure_kind_origins_mut().insert(hir_id, (place_span, place));
456 fn visit_coercion_casts(&mut self) {
457 let fcx_typeck_results = self.fcx.typeck_results.borrow();
458 let fcx_coercion_casts = fcx_typeck_results.coercion_casts();
459 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
461 for local_id in fcx_coercion_casts {
462 self.typeck_results.set_coercion_cast(*local_id);
466 fn visit_user_provided_tys(&mut self) {
467 let fcx_typeck_results = self.fcx.typeck_results.borrow();
468 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
469 let common_hir_owner = fcx_typeck_results.hir_owner;
471 let mut errors_buffer = Vec::new();
472 for (&local_id, c_ty) in fcx_typeck_results.user_provided_types().iter() {
473 let hir_id = hir::HirId { owner: common_hir_owner, local_id };
475 if cfg!(debug_assertions) && c_ty.needs_infer() {
477 hir_id.to_span(self.fcx.tcx),
478 "writeback: `{:?}` has inference variables",
483 self.typeck_results.user_provided_types_mut().insert(hir_id, *c_ty);
485 if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
486 if self.rustc_dump_user_substs {
487 // This is a unit-testing mechanism.
488 let span = self.tcx().hir().span(hir_id);
489 // We need to buffer the errors in order to guarantee a consistent
490 // order when emitting them.
494 .struct_span_err(span, &format!("user substs: {:?}", user_substs));
495 err.buffer(&mut errors_buffer);
500 if !errors_buffer.is_empty() {
501 errors_buffer.sort_by_key(|diag| diag.span.primary_span());
502 for mut diag in errors_buffer {
503 self.tcx().sess.diagnostic().emit_diagnostic(&mut diag);
508 fn visit_user_provided_sigs(&mut self) {
509 let fcx_typeck_results = self.fcx.typeck_results.borrow();
510 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
512 for (&def_id, c_sig) in fcx_typeck_results.user_provided_sigs.iter() {
513 if cfg!(debug_assertions) && c_sig.needs_infer() {
515 self.fcx.tcx.def_span(def_id),
516 "writeback: `{:?}` has inference variables",
521 self.typeck_results.user_provided_sigs.insert(def_id, *c_sig);
525 fn visit_generator_interior_types(&mut self) {
526 let fcx_typeck_results = self.fcx.typeck_results.borrow();
527 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
528 self.typeck_results.generator_interior_types =
529 fcx_typeck_results.generator_interior_types.clone();
532 #[instrument(skip(self), level = "debug")]
533 fn visit_opaque_types(&mut self) {
535 self.fcx.infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
536 for (opaque_type_key, decl) in opaque_types {
537 let hidden_type = self.resolve(decl.hidden_type, &decl.hidden_type.span);
538 let opaque_type_key = self.resolve(opaque_type_key, &decl.hidden_type.span);
540 struct RecursionChecker {
543 impl<'tcx> ty::TypeVisitor<'tcx> for RecursionChecker {
545 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
546 if let ty::Opaque(def_id, _) = *t.kind() {
547 if def_id == self.def_id.to_def_id() {
548 return ControlFlow::Break(());
551 t.super_visit_with(self)
555 .visit_with(&mut RecursionChecker { def_id: opaque_type_key.def_id })
561 let hidden_type = hidden_type.remap_generic_params_to_declaration_params(
568 self.typeck_results.concrete_opaque_types.insert(opaque_type_key.def_id, hidden_type);
572 fn visit_field_id(&mut self, hir_id: hir::HirId) {
573 if let Some(index) = self.fcx.typeck_results.borrow_mut().field_indices_mut().remove(hir_id)
575 self.typeck_results.field_indices_mut().insert(hir_id, index);
579 #[instrument(skip(self, span), level = "debug")]
580 fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
581 // Export associated path extensions and method resolutions.
583 self.fcx.typeck_results.borrow_mut().type_dependent_defs_mut().remove(hir_id)
585 self.typeck_results.type_dependent_defs_mut().insert(hir_id, def);
588 // Resolve any borrowings for the node with id `node_id`
589 self.visit_adjustments(span, hir_id);
591 // Resolve the type of the node with id `node_id`
592 let n_ty = self.fcx.node_ty(hir_id);
593 let n_ty = self.resolve(n_ty, &span);
594 self.write_ty_to_typeck_results(hir_id, n_ty);
597 // Resolve any substitutions
598 if let Some(substs) = self.fcx.typeck_results.borrow().node_substs_opt(hir_id) {
599 let substs = self.resolve(substs, &span);
600 debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
601 assert!(!substs.needs_infer() && !substs.has_placeholders());
602 self.typeck_results.node_substs_mut().insert(hir_id, substs);
606 #[instrument(skip(self, span), level = "debug")]
607 fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
608 let adjustment = self.fcx.typeck_results.borrow_mut().adjustments_mut().remove(hir_id);
611 debug!("no adjustments for node");
614 Some(adjustment) => {
615 let resolved_adjustment = self.resolve(adjustment, &span);
616 debug!(?resolved_adjustment);
617 self.typeck_results.adjustments_mut().insert(hir_id, resolved_adjustment);
622 #[instrument(skip(self, span), level = "debug")]
623 fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
624 let adjustment = self.fcx.typeck_results.borrow_mut().pat_adjustments_mut().remove(hir_id);
627 debug!("no pat_adjustments for node");
630 Some(adjustment) => {
631 let resolved_adjustment = self.resolve(adjustment, &span);
632 debug!(?resolved_adjustment);
633 self.typeck_results.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
638 fn visit_liberated_fn_sigs(&mut self) {
639 let fcx_typeck_results = self.fcx.typeck_results.borrow();
640 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
641 let common_hir_owner = fcx_typeck_results.hir_owner;
643 for (&local_id, &fn_sig) in fcx_typeck_results.liberated_fn_sigs().iter() {
644 let hir_id = hir::HirId { owner: common_hir_owner, local_id };
645 let fn_sig = self.resolve(fn_sig, &hir_id);
646 self.typeck_results.liberated_fn_sigs_mut().insert(hir_id, fn_sig);
650 fn visit_fru_field_types(&mut self) {
651 let fcx_typeck_results = self.fcx.typeck_results.borrow();
652 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
653 let common_hir_owner = fcx_typeck_results.hir_owner;
655 for (&local_id, ftys) in fcx_typeck_results.fru_field_types().iter() {
656 let hir_id = hir::HirId { owner: common_hir_owner, local_id };
657 let ftys = self.resolve(ftys.clone(), &hir_id);
658 self.typeck_results.fru_field_types_mut().insert(hir_id, ftys);
662 fn resolve<T>(&mut self, x: T, span: &dyn Locatable) -> T
664 T: TypeFoldable<'tcx>,
666 let mut resolver = Resolver::new(self.fcx, span, self.body);
667 let x = x.fold_with(&mut resolver);
668 if cfg!(debug_assertions) && x.needs_infer() {
669 span_bug!(span.to_span(self.fcx.tcx), "writeback: `{:?}` has inference variables", x);
672 // We may have introduced e.g. `ty::Error`, if inference failed, make sure
673 // to mark the `TypeckResults` as tainted in that case, so that downstream
674 // users of the typeck results don't produce extra errors, or worse, ICEs.
675 if resolver.replaced_with_error {
676 // FIXME(eddyb) keep track of `ErrorGuaranteed` from where the error was emitted.
677 self.typeck_results.tainted_by_errors =
678 Some(ErrorGuaranteed::unchecked_claim_error_was_emitted());
685 pub(crate) trait Locatable {
686 fn to_span(&self, tcx: TyCtxt<'_>) -> Span;
689 impl Locatable for Span {
690 fn to_span(&self, _: TyCtxt<'_>) -> Span {
695 impl Locatable for hir::HirId {
696 fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
697 tcx.hir().span(*self)
701 /// The Resolver. This is the type folding engine that detects
702 /// unresolved types and so forth.
703 struct Resolver<'cx, 'tcx> {
705 infcx: &'cx InferCtxt<'tcx>,
706 span: &'cx dyn Locatable,
707 body: &'tcx hir::Body<'tcx>,
709 /// Set to `true` if any `Ty` or `ty::Const` had to be replaced with an `Error`.
710 replaced_with_error: bool,
713 impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
715 fcx: &'cx FnCtxt<'cx, 'tcx>,
716 span: &'cx dyn Locatable,
717 body: &'tcx hir::Body<'tcx>,
718 ) -> Resolver<'cx, 'tcx> {
719 Resolver { tcx: fcx.tcx, infcx: fcx, span, body, replaced_with_error: false }
722 fn report_error(&self, p: impl Into<ty::GenericArg<'tcx>>) {
723 if !self.tcx.sess.has_errors().is_some() {
726 .emit_inference_failure_err(
727 Some(self.body.id()),
728 self.span.to_span(self.tcx),
738 struct EraseEarlyRegions<'tcx> {
742 impl<'tcx> TypeFolder<'tcx> for EraseEarlyRegions<'tcx> {
743 fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
746 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
747 if ty.has_type_flags(ty::TypeFlags::HAS_FREE_REGIONS) {
748 ty.super_fold_with(self)
753 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
754 if r.is_late_bound() { r } else { self.tcx.lifetimes.re_erased }
758 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
759 fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
763 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
764 match self.infcx.fully_resolve(t) {
766 // Do not anonymize late-bound regions
767 // (e.g. keep `for<'a>` named `for<'a>`).
768 // This allows NLL to generate error messages that
769 // refer to the higher-ranked lifetime names written by the user.
770 EraseEarlyRegions { tcx: self.tcx }.fold_ty(t)
773 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable", t);
774 self.report_error(t);
775 self.replaced_with_error = true;
776 self.tcx().ty_error()
781 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
782 debug_assert!(!r.is_late_bound(), "Should not be resolving bound region.");
783 self.tcx.lifetimes.re_erased
786 fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
787 match self.infcx.fully_resolve(ct) {
788 Ok(ct) => self.tcx.erase_regions(ct),
790 debug!("Resolver::fold_const: input const `{:?}` not fully resolvable", ct);
791 self.report_error(ct);
792 self.replaced_with_error = true;
793 self.tcx().const_error(ct.ty())
799 ///////////////////////////////////////////////////////////////////////////
800 // During type check, we store promises with the result of trait
801 // lookup rather than the actual results (because the results are not
802 // necessarily available immediately). These routines unwind the
803 // promises. It is expected that we will have already reported any
804 // errors that may be encountered, so if the promises store an error,
805 // a dummy result is returned.