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
5 use crate::check::FnCtxt;
7 use rustc_data_structures::stable_map::FxHashMap;
8 use rustc_errors::ErrorReported;
10 use rustc_hir::def_id::DefId;
11 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
12 use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
13 use rustc_infer::infer::InferCtxt;
14 use rustc_middle::hir::place::Place as HirPlace;
15 use rustc_middle::mir::FakeReadCause;
16 use rustc_middle::ty::adjustment::{Adjust, Adjustment, PointerCast};
17 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder};
18 use rustc_middle::ty::{self, ClosureSizeProfileData, Ty, TyCtxt};
19 use rustc_span::symbol::sym;
21 use rustc_trait_selection::opaque_types::InferCtxtExt;
25 ///////////////////////////////////////////////////////////////////////////
28 // During type inference, partially inferred types are
29 // represented using Type variables (ty::Infer). These don't appear in
30 // the final TypeckResults since all of the types should have been
31 // inferred once typeck is done.
32 // When type inference is running however, having to update the typeck
33 // typeck results every time a new type is inferred would be unreasonably slow,
34 // so instead all of the replacement happens at the end in
35 // resolve_type_vars_in_body, which creates a new TypeTables which
36 // doesn't contain any inference types.
37 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
38 pub fn resolve_type_vars_in_body(
40 body: &'tcx hir::Body<'tcx>,
41 ) -> &'tcx ty::TypeckResults<'tcx> {
42 let item_id = self.tcx.hir().body_owner(body.id());
43 let item_def_id = self.tcx.hir().local_def_id(item_id);
45 // This attribute causes us to dump some writeback information
46 // in the form of errors, which is uSymbol for unit tests.
47 let rustc_dump_user_substs =
48 self.tcx.has_attr(item_def_id.to_def_id(), sym::rustc_dump_user_substs);
50 let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_substs);
51 for param in body.params {
52 wbcx.visit_node_id(param.pat.span, param.hir_id);
54 // Type only exists for constants and statics, not functions.
55 match self.tcx.hir().body_owner_kind(item_id) {
56 hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => {
57 wbcx.visit_node_id(body.value.span, item_id);
59 hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => (),
61 wbcx.visit_body(body);
62 wbcx.visit_min_capture_map();
63 wbcx.eval_closure_size();
64 wbcx.visit_fake_reads_map();
65 wbcx.visit_closures();
66 wbcx.visit_liberated_fn_sigs();
67 wbcx.visit_fru_field_types();
68 wbcx.visit_opaque_types(body.value.span);
69 wbcx.visit_coercion_casts();
70 wbcx.visit_user_provided_tys();
71 wbcx.visit_user_provided_sigs();
72 wbcx.visit_generator_interior_types();
74 let used_trait_imports =
75 mem::take(&mut self.typeck_results.borrow_mut().used_trait_imports);
76 debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
77 wbcx.typeck_results.used_trait_imports = used_trait_imports;
79 wbcx.typeck_results.treat_byte_string_as_slice =
80 mem::take(&mut self.typeck_results.borrow_mut().treat_byte_string_as_slice);
82 if self.is_tainted_by_errors() {
83 // FIXME(eddyb) keep track of `ErrorReported` from where the error was emitted.
84 wbcx.typeck_results.tainted_by_errors = Some(ErrorReported);
87 debug!("writeback: typeck results for {:?} are {:#?}", item_def_id, wbcx.typeck_results);
89 self.tcx.arena.alloc(wbcx.typeck_results)
93 ///////////////////////////////////////////////////////////////////////////
94 // The Writeback context. This visitor walks the HIR, checking the
95 // fn-specific typeck results to find references to types or regions. It
96 // resolves those regions to remove inference variables and writes the
97 // final result back into the master typeck results in the tcx. Here and
98 // there, it applies a few ad-hoc checks that were not convenient to
101 struct WritebackCx<'cx, 'tcx> {
102 fcx: &'cx FnCtxt<'cx, 'tcx>,
104 typeck_results: ty::TypeckResults<'tcx>,
106 body: &'tcx hir::Body<'tcx>,
108 rustc_dump_user_substs: bool,
111 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
113 fcx: &'cx FnCtxt<'cx, 'tcx>,
114 body: &'tcx hir::Body<'tcx>,
115 rustc_dump_user_substs: bool,
116 ) -> WritebackCx<'cx, 'tcx> {
117 let owner = body.id().hir_id.owner;
121 typeck_results: ty::TypeckResults::new(owner),
123 rustc_dump_user_substs,
127 fn tcx(&self) -> TyCtxt<'tcx> {
131 fn write_ty_to_typeck_results(&mut self, hir_id: hir::HirId, ty: Ty<'tcx>) {
132 debug!("write_ty_to_typeck_results({:?}, {:?})", hir_id, ty);
133 assert!(!ty.needs_infer() && !ty.has_placeholders() && !ty.has_free_regions(self.tcx()));
134 self.typeck_results.node_types_mut().insert(hir_id, ty);
137 // Hacky hack: During type-checking, we treat *all* operators
138 // as potentially overloaded. But then, during writeback, if
139 // we observe that something like `a+b` is (known to be)
140 // operating on scalars, we clear the overload.
141 fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr<'_>) {
143 hir::ExprKind::Unary(hir::UnOp::Neg | hir::UnOp::Not, inner) => {
144 let inner_ty = self.fcx.node_ty(inner.hir_id);
145 let inner_ty = self.fcx.resolve_vars_if_possible(inner_ty);
147 if inner_ty.is_scalar() {
148 let mut typeck_results = self.fcx.typeck_results.borrow_mut();
149 typeck_results.type_dependent_defs_mut().remove(e.hir_id);
150 typeck_results.node_substs_mut().remove(e.hir_id);
153 hir::ExprKind::Binary(ref op, lhs, rhs) | hir::ExprKind::AssignOp(ref op, lhs, rhs) => {
154 let lhs_ty = self.fcx.node_ty(lhs.hir_id);
155 let lhs_ty = self.fcx.resolve_vars_if_possible(lhs_ty);
157 let rhs_ty = self.fcx.node_ty(rhs.hir_id);
158 let rhs_ty = self.fcx.resolve_vars_if_possible(rhs_ty);
160 if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
161 let mut typeck_results = self.fcx.typeck_results.borrow_mut();
162 typeck_results.type_dependent_defs_mut().remove(e.hir_id);
163 typeck_results.node_substs_mut().remove(e.hir_id);
166 hir::ExprKind::Binary(..) => {
167 if !op.node.is_by_value() {
168 let mut adjustments = typeck_results.adjustments_mut();
169 if let Some(a) = adjustments.get_mut(lhs.hir_id) {
172 if let Some(a) = adjustments.get_mut(rhs.hir_id) {
177 hir::ExprKind::AssignOp(..)
178 if let Some(a) = typeck_results.adjustments_mut().get_mut(lhs.hir_id) =>
190 // Similar to operators, indexing is always assumed to be overloaded
191 // Here, correct cases where an indexing expression can be simplified
192 // to use builtin indexing because the index type is known to be
194 fn fix_index_builtin_expr(&mut self, e: &hir::Expr<'_>) {
195 if let hir::ExprKind::Index(ref base, ref index) = e.kind {
196 let mut typeck_results = self.fcx.typeck_results.borrow_mut();
198 // All valid indexing looks like this; might encounter non-valid indexes at this point.
199 let base_ty = typeck_results
200 .expr_ty_adjusted_opt(base)
201 .map(|t| self.fcx.resolve_vars_if_possible(t).kind());
202 if base_ty.is_none() {
203 // When encountering `return [0][0]` outside of a `fn` body we can encounter a base
204 // that isn't in the type table. We assume more relevant errors have already been
205 // emitted, so we delay an ICE if none have. (#64638)
206 self.tcx().sess.delay_span_bug(e.span, &format!("bad base: `{:?}`", base));
208 if let Some(ty::Ref(_, base_ty, _)) = base_ty {
209 let index_ty = typeck_results.expr_ty_adjusted_opt(index).unwrap_or_else(|| {
210 // When encountering `return [0][0]` outside of a `fn` body we would attempt
211 // to access an unexistend index. We assume that more relevant errors will
212 // already have been emitted, so we only gate on this with an ICE if no
213 // error has been emitted. (#64638)
214 self.fcx.tcx.ty_error_with_message(
216 &format!("bad index {:?} for base: `{:?}`", index, base),
219 let index_ty = self.fcx.resolve_vars_if_possible(index_ty);
221 if base_ty.builtin_index().is_some() && index_ty == self.fcx.tcx.types.usize {
222 // Remove the method call record
223 typeck_results.type_dependent_defs_mut().remove(e.hir_id);
224 typeck_results.node_substs_mut().remove(e.hir_id);
226 if let Some(a) = typeck_results.adjustments_mut().get_mut(base.hir_id) {
227 // Discard the need for a mutable borrow
229 // Extra adjustment made when indexing causes a drop
230 // of size information - we need to get rid of it
231 // Since this is "after" the other adjustment to be
232 // discarded, we do an extra `pop()`
233 if let Some(Adjustment {
234 kind: Adjust::Pointer(PointerCast::Unsize), ..
237 // So the borrow discard actually happens here
247 ///////////////////////////////////////////////////////////////////////////
248 // Impl of Visitor for Resolver
250 // This is the master code which walks the AST. It delegates most of
251 // the heavy lifting to the generic visit and resolve functions
252 // below. In general, a function is made into a `visitor` if it must
253 // traffic in node-ids or update typeck results in the type context etc.
255 impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
256 type Map = intravisit::ErasedMap<'tcx>;
258 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
259 NestedVisitorMap::None
262 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
263 self.fix_scalar_builtin_expr(e);
264 self.fix_index_builtin_expr(e);
266 self.visit_node_id(e.span, e.hir_id);
269 hir::ExprKind::Closure(_, _, body, _, _) => {
270 let body = self.fcx.tcx.hir().body(body);
271 for param in body.params {
272 self.visit_node_id(e.span, param.hir_id);
275 self.visit_body(body);
277 hir::ExprKind::Struct(_, fields, _) => {
278 for field in fields {
279 self.visit_field_id(field.hir_id);
282 hir::ExprKind::Field(..) => {
283 self.visit_field_id(e.hir_id);
285 hir::ExprKind::ConstBlock(anon_const) => {
286 self.visit_node_id(e.span, anon_const.hir_id);
288 let body = self.tcx().hir().body(anon_const.body);
289 self.visit_body(body);
294 intravisit::walk_expr(self, e);
297 fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
298 self.visit_node_id(b.span, b.hir_id);
299 intravisit::walk_block(self, b);
302 fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
304 hir::PatKind::Binding(..) => {
305 let typeck_results = self.fcx.typeck_results.borrow();
307 typeck_results.extract_binding_mode(self.tcx().sess, p.hir_id, p.span)
309 self.typeck_results.pat_binding_modes_mut().insert(p.hir_id, bm);
312 hir::PatKind::Struct(_, fields, _) => {
313 for field in fields {
314 self.visit_field_id(field.hir_id);
320 self.visit_pat_adjustments(p.span, p.hir_id);
322 self.visit_node_id(p.span, p.hir_id);
323 intravisit::walk_pat(self, p);
326 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
327 intravisit::walk_local(self, l);
328 let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
329 let var_ty = self.resolve(var_ty, &l.span);
330 self.write_ty_to_typeck_results(l.hir_id, var_ty);
333 fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx>) {
334 intravisit::walk_ty(self, hir_ty);
335 let ty = self.fcx.node_ty(hir_ty.hir_id);
336 let ty = self.resolve(ty, &hir_ty.span);
337 self.write_ty_to_typeck_results(hir_ty.hir_id, ty);
340 fn visit_infer(&mut self, inf: &'tcx hir::InferArg) {
341 intravisit::walk_inf(self, inf);
342 // Ignore cases where the inference is a const.
343 if let Some(ty) = self.fcx.node_ty_opt(inf.hir_id) {
344 let ty = self.resolve(ty, &inf.span);
345 self.write_ty_to_typeck_results(inf.hir_id, ty);
350 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
351 fn eval_closure_size(&mut self) {
352 let mut res: FxHashMap<DefId, ClosureSizeProfileData<'tcx>> = Default::default();
353 for (closure_def_id, data) in self.fcx.typeck_results.borrow().closure_size_eval.iter() {
355 self.tcx().hir().local_def_id_to_hir_id(closure_def_id.expect_local());
357 let data = self.resolve(*data, &closure_hir_id);
359 res.insert(*closure_def_id, data);
362 self.typeck_results.closure_size_eval = res;
364 fn visit_min_capture_map(&mut self) {
365 let mut min_captures_wb = ty::MinCaptureInformationMap::with_capacity_and_hasher(
366 self.fcx.typeck_results.borrow().closure_min_captures.len(),
369 for (closure_def_id, root_min_captures) in
370 self.fcx.typeck_results.borrow().closure_min_captures.iter()
372 let mut root_var_map_wb = ty::RootVariableMinCaptureList::with_capacity_and_hasher(
373 root_min_captures.len(),
376 for (var_hir_id, min_list) in root_min_captures.iter() {
377 let min_list_wb = min_list
379 .map(|captured_place| {
380 let locatable = captured_place.info.path_expr_id.unwrap_or_else(|| {
381 self.tcx().hir().local_def_id_to_hir_id(closure_def_id.expect_local())
384 self.resolve(captured_place.clone(), &locatable)
387 root_var_map_wb.insert(*var_hir_id, min_list_wb);
389 min_captures_wb.insert(*closure_def_id, root_var_map_wb);
392 self.typeck_results.closure_min_captures = min_captures_wb;
395 fn visit_fake_reads_map(&mut self) {
396 let mut resolved_closure_fake_reads: FxHashMap<
398 Vec<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>,
399 > = Default::default();
400 for (closure_def_id, fake_reads) in
401 self.fcx.typeck_results.borrow().closure_fake_reads.iter()
403 let mut resolved_fake_reads = Vec::<(HirPlace<'tcx>, FakeReadCause, hir::HirId)>::new();
404 for (place, cause, hir_id) in fake_reads.iter() {
406 self.tcx().hir().local_def_id_to_hir_id(closure_def_id.expect_local());
408 let resolved_fake_read = self.resolve(place.clone(), &locatable);
409 resolved_fake_reads.push((resolved_fake_read, *cause, *hir_id));
411 resolved_closure_fake_reads.insert(*closure_def_id, resolved_fake_reads);
413 self.typeck_results.closure_fake_reads = resolved_closure_fake_reads;
416 fn visit_closures(&mut self) {
417 let fcx_typeck_results = self.fcx.typeck_results.borrow();
418 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
419 let common_hir_owner = fcx_typeck_results.hir_owner;
421 for (id, origin) in fcx_typeck_results.closure_kind_origins().iter() {
422 let hir_id = hir::HirId { owner: common_hir_owner, local_id: *id };
423 let place_span = origin.0;
424 let place = self.resolve(origin.1.clone(), &place_span);
425 self.typeck_results.closure_kind_origins_mut().insert(hir_id, (place_span, place));
429 fn visit_coercion_casts(&mut self) {
430 let fcx_typeck_results = self.fcx.typeck_results.borrow();
431 let fcx_coercion_casts = fcx_typeck_results.coercion_casts();
432 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
434 for local_id in fcx_coercion_casts {
435 self.typeck_results.set_coercion_cast(*local_id);
439 fn visit_user_provided_tys(&mut self) {
440 let fcx_typeck_results = self.fcx.typeck_results.borrow();
441 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
442 let common_hir_owner = fcx_typeck_results.hir_owner;
444 let mut errors_buffer = Vec::new();
445 for (&local_id, c_ty) in fcx_typeck_results.user_provided_types().iter() {
446 let hir_id = hir::HirId { owner: common_hir_owner, local_id };
448 if cfg!(debug_assertions) && c_ty.needs_infer() {
450 hir_id.to_span(self.fcx.tcx),
451 "writeback: `{:?}` has inference variables",
456 self.typeck_results.user_provided_types_mut().insert(hir_id, *c_ty);
458 if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
459 if self.rustc_dump_user_substs {
460 // This is a unit-testing mechanism.
461 let span = self.tcx().hir().span(hir_id);
462 // We need to buffer the errors in order to guarantee a consistent
463 // order when emitting them.
467 .struct_span_err(span, &format!("user substs: {:?}", user_substs));
468 err.buffer(&mut errors_buffer);
473 if !errors_buffer.is_empty() {
474 errors_buffer.sort_by_key(|diag| diag.span.primary_span());
475 for diag in errors_buffer.drain(..) {
476 self.tcx().sess.diagnostic().emit_diagnostic(&diag);
481 fn visit_user_provided_sigs(&mut self) {
482 let fcx_typeck_results = self.fcx.typeck_results.borrow();
483 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
485 for (&def_id, c_sig) in fcx_typeck_results.user_provided_sigs.iter() {
486 if cfg!(debug_assertions) && c_sig.needs_infer() {
488 self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
489 "writeback: `{:?}` has inference variables",
494 self.typeck_results.user_provided_sigs.insert(def_id, *c_sig);
498 fn visit_generator_interior_types(&mut self) {
499 let fcx_typeck_results = self.fcx.typeck_results.borrow();
500 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
501 self.typeck_results.generator_interior_types =
502 fcx_typeck_results.generator_interior_types.clone();
505 #[instrument(skip(self, span), level = "debug")]
506 fn visit_opaque_types(&mut self, span: Span) {
507 let opaque_types = self.fcx.infcx.inner.borrow().opaque_types.clone();
508 for (opaque_type_key, opaque_defn) in opaque_types {
510 self.tcx().hir().local_def_id_to_hir_id(opaque_type_key.def_id.expect_local());
511 let instantiated_ty = self.resolve(opaque_defn.concrete_ty, &hir_id);
513 debug_assert!(!instantiated_ty.has_escaping_bound_vars());
515 let opaque_type_key = self.fcx.fully_resolve(opaque_type_key).unwrap();
518 // * `fn foo<T>() -> Foo<T>`
519 // * `fn foo<T: Bound + Other>() -> Foo<T>`
520 // from being defining.
522 // Also replace all generic params with the ones from the opaque type
523 // definition so that
525 // type Foo<T> = impl Baz + 'static;
526 // fn foo<U>() -> Foo<U> { .. }
528 // figures out the concrete type with `U`, but the stored type is with `T`.
530 // FIXME: why are we calling this here? This seems too early, and duplicated.
531 let definition_ty = self.fcx.infer_opaque_definition_from_instantiation(
537 let mut skip_add = false;
539 if let ty::Opaque(definition_ty_def_id, _substs) = *definition_ty.kind() {
540 if opaque_defn.origin == hir::OpaqueTyOrigin::TyAlias {
541 if opaque_type_key.def_id == definition_ty_def_id {
543 "skipping adding concrete definition for opaque type {:?} {:?}",
544 opaque_defn, opaque_type_key.def_id
551 if opaque_type_key.substs.needs_infer() {
552 span_bug!(span, "{:#?} has inference variables", opaque_type_key.substs)
555 // We only want to add an entry into `concrete_opaque_types`
556 // if we actually found a defining usage of this opaque type.
557 // Otherwise, we do nothing - we'll either find a defining usage
558 // in some other location, or we'll end up emitting an error due
559 // to the lack of defining usage
561 self.typeck_results.concrete_opaque_types.insert(opaque_type_key.def_id);
566 fn visit_field_id(&mut self, hir_id: hir::HirId) {
567 if let Some(index) = self.fcx.typeck_results.borrow_mut().field_indices_mut().remove(hir_id)
569 self.typeck_results.field_indices_mut().insert(hir_id, index);
573 #[instrument(skip(self, span), level = "debug")]
574 fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
575 // Export associated path extensions and method resolutions.
577 self.fcx.typeck_results.borrow_mut().type_dependent_defs_mut().remove(hir_id)
579 self.typeck_results.type_dependent_defs_mut().insert(hir_id, def);
582 // Resolve any borrowings for the node with id `node_id`
583 self.visit_adjustments(span, hir_id);
585 // Resolve the type of the node with id `node_id`
586 let n_ty = self.fcx.node_ty(hir_id);
587 let n_ty = self.resolve(n_ty, &span);
588 self.write_ty_to_typeck_results(hir_id, n_ty);
591 // Resolve any substitutions
592 if let Some(substs) = self.fcx.typeck_results.borrow().node_substs_opt(hir_id) {
593 let substs = self.resolve(substs, &span);
594 debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
595 assert!(!substs.needs_infer() && !substs.has_placeholders());
596 self.typeck_results.node_substs_mut().insert(hir_id, substs);
600 #[instrument(skip(self, span), level = "debug")]
601 fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
602 let adjustment = self.fcx.typeck_results.borrow_mut().adjustments_mut().remove(hir_id);
605 debug!("no adjustments for node");
608 Some(adjustment) => {
609 let resolved_adjustment = self.resolve(adjustment, &span);
610 debug!(?resolved_adjustment);
611 self.typeck_results.adjustments_mut().insert(hir_id, resolved_adjustment);
616 #[instrument(skip(self, span), level = "debug")]
617 fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
618 let adjustment = self.fcx.typeck_results.borrow_mut().pat_adjustments_mut().remove(hir_id);
621 debug!("no pat_adjustments for node");
624 Some(adjustment) => {
625 let resolved_adjustment = self.resolve(adjustment, &span);
626 debug!(?resolved_adjustment);
627 self.typeck_results.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
632 fn visit_liberated_fn_sigs(&mut self) {
633 let fcx_typeck_results = self.fcx.typeck_results.borrow();
634 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
635 let common_hir_owner = fcx_typeck_results.hir_owner;
637 for (&local_id, &fn_sig) in fcx_typeck_results.liberated_fn_sigs().iter() {
638 let hir_id = hir::HirId { owner: common_hir_owner, local_id };
639 let fn_sig = self.resolve(fn_sig, &hir_id);
640 self.typeck_results.liberated_fn_sigs_mut().insert(hir_id, fn_sig);
644 fn visit_fru_field_types(&mut self) {
645 let fcx_typeck_results = self.fcx.typeck_results.borrow();
646 assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
647 let common_hir_owner = fcx_typeck_results.hir_owner;
649 for (&local_id, ftys) in fcx_typeck_results.fru_field_types().iter() {
650 let hir_id = hir::HirId { owner: common_hir_owner, local_id };
651 let ftys = self.resolve(ftys.clone(), &hir_id);
652 self.typeck_results.fru_field_types_mut().insert(hir_id, ftys);
656 fn resolve<T>(&mut self, x: T, span: &dyn Locatable) -> T
658 T: TypeFoldable<'tcx>,
660 let mut resolver = Resolver::new(self.fcx, span, self.body);
661 let x = x.fold_with(&mut resolver);
662 if cfg!(debug_assertions) && x.needs_infer() {
663 span_bug!(span.to_span(self.fcx.tcx), "writeback: `{:?}` has inference variables", x);
666 // We may have introduced e.g. `ty::Error`, if inference failed, make sure
667 // to mark the `TypeckResults` as tainted in that case, so that downstream
668 // users of the typeck results don't produce extra errors, or worse, ICEs.
669 if resolver.replaced_with_error {
670 // FIXME(eddyb) keep track of `ErrorReported` from where the error was emitted.
671 self.typeck_results.tainted_by_errors = Some(ErrorReported);
678 crate trait Locatable {
679 fn to_span(&self, tcx: TyCtxt<'_>) -> Span;
682 impl Locatable for Span {
683 fn to_span(&self, _: TyCtxt<'_>) -> Span {
688 impl Locatable for hir::HirId {
689 fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
690 tcx.hir().span(*self)
694 /// The Resolver. This is the type folding engine that detects
695 /// unresolved types and so forth.
696 struct Resolver<'cx, 'tcx> {
698 infcx: &'cx InferCtxt<'cx, 'tcx>,
699 span: &'cx dyn Locatable,
700 body: &'tcx hir::Body<'tcx>,
702 /// Set to `true` if any `Ty` or `ty::Const` had to be replaced with an `Error`.
703 replaced_with_error: bool,
706 impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
708 fcx: &'cx FnCtxt<'cx, 'tcx>,
709 span: &'cx dyn Locatable,
710 body: &'tcx hir::Body<'tcx>,
711 ) -> Resolver<'cx, 'tcx> {
712 Resolver { tcx: fcx.tcx, infcx: fcx, span, body, replaced_with_error: false }
715 fn report_type_error(&self, t: Ty<'tcx>) {
716 if !self.tcx.sess.has_errors() {
718 .emit_inference_failure_err(
719 Some(self.body.id()),
720 self.span.to_span(self.tcx),
729 fn report_const_error(&self, c: &'tcx ty::Const<'tcx>) {
730 if !self.tcx.sess.has_errors() {
732 .emit_inference_failure_err(
733 Some(self.body.id()),
734 self.span.to_span(self.tcx),
744 struct EraseEarlyRegions<'tcx> {
748 impl<'tcx> TypeFolder<'tcx> for EraseEarlyRegions<'tcx> {
749 fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
752 fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
753 if ty.has_type_flags(ty::TypeFlags::HAS_POTENTIAL_FREE_REGIONS) {
754 ty.super_fold_with(self)
759 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
760 if let ty::ReLateBound(..) = r { r } else { self.tcx.lifetimes.re_erased }
764 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
765 fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
769 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
770 match self.infcx.fully_resolve(t) {
772 // Do not anonymize late-bound regions
773 // (e.g. keep `for<'a>` named `for<'a>`).
774 // This allows NLL to generate error messages that
775 // refer to the higher-ranked lifetime names written by the user.
776 EraseEarlyRegions { tcx: self.infcx.tcx }.fold_ty(t)
779 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable", t);
780 self.report_type_error(t);
781 self.replaced_with_error = true;
782 self.tcx().ty_error()
787 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
788 debug_assert!(!r.is_late_bound(), "Should not be resolving bound region.");
789 self.tcx.lifetimes.re_erased
792 fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
793 match self.infcx.fully_resolve(ct) {
794 Ok(ct) => self.infcx.tcx.erase_regions(ct),
796 debug!("Resolver::fold_const: input const `{:?}` not fully resolvable", ct);
797 self.report_const_error(ct);
798 self.replaced_with_error = true;
799 self.tcx().const_error(ct.ty)
805 ///////////////////////////////////////////////////////////////////////////
806 // During type check, we store promises with the result of trait
807 // lookup rather than the actual results (because the results are not
808 // necessarily available immediately). These routines unwind the
809 // promises. It is expected that we will have already reported any
810 // errors that may be encountered, so if the promises store an error,
811 // a dummy result is returned.