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::hir::map::Map;
8 use rustc::infer::error_reporting::TypeAnnotationNeeded::E0282;
9 use rustc::infer::InferCtxt;
10 use rustc::ty::adjustment::{Adjust, Adjustment, PointerCast};
11 use rustc::ty::fold::{TypeFoldable, TypeFolder};
12 use rustc::ty::{self, Ty, TyCtxt};
13 use rustc_data_structures::sync::Lrc;
15 use rustc_hir::def_id::{DefId, DefIdSet, DefIndex};
16 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
17 use rustc_span::symbol::sym;
22 ///////////////////////////////////////////////////////////////////////////
25 // During type inference, partially inferred types are
26 // represented using Type variables (ty::Infer). These don't appear in
27 // the final TypeckTables since all of the types should have been
28 // inferred once typeck_tables_of is done.
29 // When type inference is running however, having to update the typeck
30 // tables every time a new type is inferred would be unreasonably slow,
31 // so instead all of the replacement happens at the end in
32 // resolve_type_vars_in_body, which creates a new TypeTables which
33 // doesn't contain any inference types.
34 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
35 pub fn resolve_type_vars_in_body(
37 body: &'tcx hir::Body<'tcx>,
38 ) -> &'tcx ty::TypeckTables<'tcx> {
39 let item_id = self.tcx.hir().body_owner(body.id());
40 let item_def_id = self.tcx.hir().local_def_id(item_id);
42 // This attribute causes us to dump some writeback information
43 // in the form of errors, which is uSymbolfor unit tests.
44 let rustc_dump_user_substs = self.tcx.has_attr(item_def_id, sym::rustc_dump_user_substs);
46 let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_substs);
47 for param in body.params {
48 wbcx.visit_node_id(param.pat.span, param.hir_id);
50 // Type only exists for constants and statics, not functions.
51 match self.tcx.hir().body_owner_kind(item_id) {
52 hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => {
53 wbcx.visit_node_id(body.value.span, item_id);
55 hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => (),
57 wbcx.visit_body(body);
58 wbcx.visit_upvar_capture_map();
59 wbcx.visit_closures();
60 wbcx.visit_liberated_fn_sigs();
61 wbcx.visit_fru_field_types();
62 wbcx.visit_opaque_types(body.value.span);
63 wbcx.visit_coercion_casts();
64 wbcx.visit_free_region_map();
65 wbcx.visit_user_provided_tys();
66 wbcx.visit_user_provided_sigs();
67 wbcx.visit_generator_interior_types();
69 let used_trait_imports = mem::replace(
70 &mut self.tables.borrow_mut().used_trait_imports,
71 Lrc::new(DefIdSet::default()),
73 debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
74 wbcx.tables.used_trait_imports = used_trait_imports;
76 wbcx.tables.upvar_list =
77 mem::replace(&mut self.tables.borrow_mut().upvar_list, Default::default());
79 wbcx.tables.tainted_by_errors = self.is_tainted_by_errors();
81 debug!("writeback: tables for {:?} are {:#?}", item_def_id, wbcx.tables);
83 self.tcx.arena.alloc(wbcx.tables)
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
95 struct WritebackCx<'cx, 'tcx> {
96 fcx: &'cx FnCtxt<'cx, 'tcx>,
98 tables: ty::TypeckTables<'tcx>,
100 body: &'tcx hir::Body<'tcx>,
102 rustc_dump_user_substs: bool,
105 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
107 fcx: &'cx FnCtxt<'cx, 'tcx>,
108 body: &'tcx hir::Body<'tcx>,
109 rustc_dump_user_substs: bool,
110 ) -> WritebackCx<'cx, 'tcx> {
111 let owner = body.id().hir_id;
115 tables: ty::TypeckTables::empty(Some(DefId::local(owner.owner))),
117 rustc_dump_user_substs,
121 fn tcx(&self) -> TyCtxt<'tcx> {
125 fn write_ty_to_tables(&mut self, hir_id: hir::HirId, ty: Ty<'tcx>) {
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);
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<'_>) {
137 hir::ExprKind::Unary(hir::UnOp::UnNeg, ref inner)
138 | hir::ExprKind::Unary(hir::UnOp::UnNot, ref inner) => {
139 let inner_ty = self.fcx.node_ty(inner.hir_id);
140 let inner_ty = self.fcx.resolve_vars_if_possible(&inner_ty);
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);
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_vars_if_possible(&lhs_ty);
153 let rhs_ty = self.fcx.node_ty(rhs.hir_id);
154 let rhs_ty = self.fcx.resolve_vars_if_possible(&rhs_ty);
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);
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());
169 hir::ExprKind::AssignOp(..) => {
170 tables.adjustments_mut().get_mut(lhs.hir_id).map(|a| a.pop());
180 // Similar to operators, indexing is always assumed to be overloaded
181 // Here, correct cases where an indexing expression can be simplified
182 // to use builtin indexing because the index type is known to be
184 fn fix_index_builtin_expr(&mut self, e: &hir::Expr<'_>) {
185 if let hir::ExprKind::Index(ref base, ref index) = e.kind {
186 let mut tables = self.fcx.tables.borrow_mut();
188 // All valid indexing looks like this; might encounter non-valid indexes at this point.
189 let base_ty = tables.expr_ty_adjusted_opt(&base).map(|t| &t.kind);
190 if base_ty.is_none() {
191 // When encountering `return [0][0]` outside of a `fn` body we can encounter a base
192 // that isn't in the type table. We assume more relevant errors have already been
193 // emitted, so we delay an ICE if none have. (#64638)
194 self.tcx().sess.delay_span_bug(e.span, &format!("bad base: `{:?}`", base));
196 if let Some(ty::Ref(_, base_ty, _)) = base_ty {
197 let index_ty = tables.expr_ty_adjusted_opt(&index).unwrap_or_else(|| {
198 // When encountering `return [0][0]` outside of a `fn` body we would attempt
199 // to access an unexistend index. We assume that more relevant errors will
200 // already have been emitted, so we only gate on this with an ICE if no
201 // error has been emitted. (#64638)
202 self.tcx().sess.delay_span_bug(
204 &format!("bad index {:?} for base: `{:?}`", index, base),
206 self.fcx.tcx.types.err
208 let index_ty = self.fcx.resolve_vars_if_possible(&index_ty);
210 if base_ty.builtin_index().is_some() && index_ty == self.fcx.tcx.types.usize {
211 // Remove the method call record
212 tables.type_dependent_defs_mut().remove(e.hir_id);
213 tables.node_substs_mut().remove(e.hir_id);
215 tables.adjustments_mut().get_mut(base.hir_id).map(|a| {
216 // Discard the need for a mutable borrow
218 // Extra adjustment made when indexing causes a drop
219 // of size information - we need to get rid of it
220 // Since this is "after" the other adjustment to be
221 // discarded, we do an extra `pop()`
223 kind: Adjust::Pointer(PointerCast::Unsize), ..
225 // So the borrow discard actually happens here
237 ///////////////////////////////////////////////////////////////////////////
238 // Impl of Visitor for Resolver
240 // This is the master code which walks the AST. It delegates most of
241 // the heavy lifting to the generic visit and resolve functions
242 // below. In general, a function is made into a `visitor` if it must
243 // traffic in node-ids or update tables in the type context etc.
245 impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
246 type Map = Map<'tcx>;
248 fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
249 NestedVisitorMap::None
252 fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
253 self.fix_scalar_builtin_expr(e);
254 self.fix_index_builtin_expr(e);
256 self.visit_node_id(e.span, e.hir_id);
259 hir::ExprKind::Closure(_, _, body, _, _) => {
260 let body = self.fcx.tcx.hir().body(body);
261 for param in body.params {
262 self.visit_node_id(e.span, param.hir_id);
265 self.visit_body(body);
267 hir::ExprKind::Struct(_, fields, _) => {
268 for field in fields {
269 self.visit_field_id(field.hir_id);
272 hir::ExprKind::Field(..) => {
273 self.visit_field_id(e.hir_id);
278 intravisit::walk_expr(self, e);
281 fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
282 self.visit_node_id(b.span, b.hir_id);
283 intravisit::walk_block(self, b);
286 fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
288 hir::PatKind::Binding(..) => {
289 let tables = self.fcx.tables.borrow();
290 if let Some(bm) = tables.extract_binding_mode(self.tcx().sess, p.hir_id, p.span) {
291 self.tables.pat_binding_modes_mut().insert(p.hir_id, bm);
294 hir::PatKind::Struct(_, fields, _) => {
295 for field in fields {
296 self.visit_field_id(field.hir_id);
302 self.visit_pat_adjustments(p.span, p.hir_id);
304 self.visit_node_id(p.span, p.hir_id);
305 intravisit::walk_pat(self, p);
308 fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
309 intravisit::walk_local(self, l);
310 let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
311 let var_ty = self.resolve(&var_ty, &l.span);
312 self.write_ty_to_tables(l.hir_id, var_ty);
315 fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx>) {
316 intravisit::walk_ty(self, hir_ty);
317 let ty = self.fcx.node_ty(hir_ty.hir_id);
318 let ty = self.resolve(&ty, &hir_ty.span);
319 self.write_ty_to_tables(hir_ty.hir_id, ty);
323 impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
324 fn visit_upvar_capture_map(&mut self) {
325 for (upvar_id, upvar_capture) in self.fcx.tables.borrow().upvar_capture_map.iter() {
326 let new_upvar_capture = match *upvar_capture {
327 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
328 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
329 let r = upvar_borrow.region;
330 let r = self.resolve(&r, &upvar_id.var_path.hir_id);
331 ty::UpvarCapture::ByRef(ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
334 debug!("Upvar capture for {:?} resolved to {:?}", upvar_id, new_upvar_capture);
335 self.tables.upvar_capture_map.insert(*upvar_id, new_upvar_capture);
339 fn visit_closures(&mut self) {
340 let fcx_tables = self.fcx.tables.borrow();
341 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
342 let common_local_id_root = fcx_tables.local_id_root.unwrap();
344 for (&id, &origin) in fcx_tables.closure_kind_origins().iter() {
345 let hir_id = hir::HirId { owner: common_local_id_root.index, local_id: id };
346 self.tables.closure_kind_origins_mut().insert(hir_id, origin);
350 fn visit_coercion_casts(&mut self) {
351 let fcx_tables = self.fcx.tables.borrow();
352 let fcx_coercion_casts = fcx_tables.coercion_casts();
353 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
355 for local_id in fcx_coercion_casts {
356 self.tables.set_coercion_cast(*local_id);
360 fn visit_free_region_map(&mut self) {
361 self.tables.free_region_map = self.fcx.tables.borrow().free_region_map.clone();
362 debug_assert!(!self.tables.free_region_map.elements().any(|r| r.has_local_value()));
365 fn visit_user_provided_tys(&mut self) {
366 let fcx_tables = self.fcx.tables.borrow();
367 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
368 let common_local_id_root = fcx_tables.local_id_root.unwrap();
370 let mut errors_buffer = Vec::new();
371 for (&local_id, c_ty) in fcx_tables.user_provided_types().iter() {
372 let hir_id = hir::HirId { owner: common_local_id_root.index, local_id };
374 if cfg!(debug_assertions) && c_ty.has_local_value() {
375 span_bug!(hir_id.to_span(self.fcx.tcx), "writeback: `{:?}` is a local value", c_ty);
378 self.tables.user_provided_types_mut().insert(hir_id, c_ty.clone());
380 if let ty::UserType::TypeOf(_, user_substs) = c_ty.value {
381 if self.rustc_dump_user_substs {
382 // This is a unit-testing mechanism.
383 let span = self.tcx().hir().span(hir_id);
384 // We need to buffer the errors in order to guarantee a consistent
385 // order when emitting them.
389 .struct_span_err(span, &format!("user substs: {:?}", user_substs));
390 err.buffer(&mut errors_buffer);
395 if !errors_buffer.is_empty() {
396 errors_buffer.sort_by_key(|diag| diag.span.primary_span());
397 for diag in errors_buffer.drain(..) {
398 self.tcx().sess.diagnostic().emit_diagnostic(&diag);
403 fn visit_user_provided_sigs(&mut self) {
404 let fcx_tables = self.fcx.tables.borrow();
405 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
407 for (&def_id, c_sig) in fcx_tables.user_provided_sigs.iter() {
408 if cfg!(debug_assertions) && c_sig.has_local_value() {
410 self.fcx.tcx.hir().span_if_local(def_id).unwrap(),
411 "writeback: `{:?}` is a local value",
416 self.tables.user_provided_sigs.insert(def_id, c_sig.clone());
420 fn visit_generator_interior_types(&mut self) {
421 let fcx_tables = self.fcx.tables.borrow();
422 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
423 self.tables.generator_interior_types = fcx_tables.generator_interior_types.clone();
426 fn visit_opaque_types(&mut self, span: Span) {
427 for (&def_id, opaque_defn) in self.fcx.opaque_types.borrow().iter() {
428 let hir_id = self.tcx().hir().as_local_hir_id(def_id).unwrap();
429 let instantiated_ty = self.resolve(&opaque_defn.concrete_ty, &hir_id);
431 debug_assert!(!instantiated_ty.has_escaping_bound_vars());
434 // * `fn foo<T>() -> Foo<T>`
435 // * `fn foo<T: Bound + Other>() -> Foo<T>`
436 // from being defining.
438 // Also replace all generic params with the ones from the opaque type
439 // definition so that
441 // type Foo<T> = impl Baz + 'static;
442 // fn foo<U>() -> Foo<U> { .. }
444 // figures out the concrete type with `U`, but the stored type is with `T`.
445 let definition_ty = self.fcx.infer_opaque_definition_from_instantiation(
452 let mut skip_add = false;
454 if let ty::Opaque(defin_ty_def_id, _substs) = definition_ty.kind {
455 if let hir::OpaqueTyOrigin::TypeAlias = opaque_defn.origin {
456 if def_id == defin_ty_def_id {
458 "skipping adding concrete definition for opaque type {:?} {:?}",
459 opaque_defn, defin_ty_def_id
466 if !opaque_defn.substs.has_local_value() {
467 // We only want to add an entry into `concrete_opaque_types`
468 // if we actually found a defining usage of this opaque type.
469 // Otherwise, we do nothing - we'll either find a defining usage
470 // in some other location, or we'll end up emitting an error due
471 // to the lack of defining usage
473 let new = ty::ResolvedOpaqueTy {
474 concrete_type: definition_ty,
475 substs: opaque_defn.substs,
478 let old = self.tables.concrete_opaque_types.insert(def_id, new);
479 if let Some(old) = old {
480 if old.concrete_type != definition_ty || old.substs != opaque_defn.substs {
483 "`visit_opaque_types` tried to write different types for the same \
484 opaque type: {:?}, {:?}, {:?}, {:?}",
494 self.tcx().sess.delay_span_bug(span, "`opaque_defn` is a local value");
499 fn visit_field_id(&mut self, hir_id: hir::HirId) {
500 if let Some(index) = self.fcx.tables.borrow_mut().field_indices_mut().remove(hir_id) {
501 self.tables.field_indices_mut().insert(hir_id, index);
505 fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
506 // Export associated path extensions and method resolutions.
507 if let Some(def) = self.fcx.tables.borrow_mut().type_dependent_defs_mut().remove(hir_id) {
508 self.tables.type_dependent_defs_mut().insert(hir_id, def);
511 // Resolve any borrowings for the node with id `node_id`
512 self.visit_adjustments(span, hir_id);
514 // Resolve the type of the node with id `node_id`
515 let n_ty = self.fcx.node_ty(hir_id);
516 let n_ty = self.resolve(&n_ty, &span);
517 self.write_ty_to_tables(hir_id, n_ty);
518 debug!("node {:?} has type {:?}", hir_id, n_ty);
520 // Resolve any substitutions
521 if let Some(substs) = self.fcx.tables.borrow().node_substs_opt(hir_id) {
522 let substs = self.resolve(&substs, &span);
523 debug!("write_substs_to_tcx({:?}, {:?})", hir_id, substs);
524 assert!(!substs.needs_infer() && !substs.has_placeholders());
525 self.tables.node_substs_mut().insert(hir_id, substs);
529 fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
530 let adjustment = self.fcx.tables.borrow_mut().adjustments_mut().remove(hir_id);
533 debug!("no adjustments for node {:?}", hir_id);
536 Some(adjustment) => {
537 let resolved_adjustment = self.resolve(&adjustment, &span);
538 debug!("adjustments for node {:?}: {:?}", hir_id, resolved_adjustment);
539 self.tables.adjustments_mut().insert(hir_id, resolved_adjustment);
544 fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
545 let adjustment = self.fcx.tables.borrow_mut().pat_adjustments_mut().remove(hir_id);
548 debug!("no pat_adjustments for node {:?}", hir_id);
551 Some(adjustment) => {
552 let resolved_adjustment = self.resolve(&adjustment, &span);
553 debug!("pat_adjustments for node {:?}: {:?}", hir_id, resolved_adjustment);
554 self.tables.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
559 fn visit_liberated_fn_sigs(&mut self) {
560 let fcx_tables = self.fcx.tables.borrow();
561 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
562 let common_local_id_root = fcx_tables.local_id_root.unwrap();
564 for (&local_id, fn_sig) in fcx_tables.liberated_fn_sigs().iter() {
565 let hir_id = hir::HirId { owner: common_local_id_root.index, local_id };
566 let fn_sig = self.resolve(fn_sig, &hir_id);
567 self.tables.liberated_fn_sigs_mut().insert(hir_id, fn_sig.clone());
571 fn visit_fru_field_types(&mut self) {
572 let fcx_tables = self.fcx.tables.borrow();
573 debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
574 let common_local_id_root = fcx_tables.local_id_root.unwrap();
576 for (&local_id, ftys) in fcx_tables.fru_field_types().iter() {
577 let hir_id = hir::HirId { owner: common_local_id_root.index, local_id };
578 let ftys = self.resolve(ftys, &hir_id);
579 self.tables.fru_field_types_mut().insert(hir_id, ftys);
583 fn resolve<T>(&self, x: &T, span: &dyn Locatable) -> T
585 T: TypeFoldable<'tcx>,
587 let x = x.fold_with(&mut Resolver::new(self.fcx, span, self.body));
588 if cfg!(debug_assertions) && x.has_local_value() {
589 span_bug!(span.to_span(self.fcx.tcx), "writeback: `{:?}` is a local value", x);
596 fn to_span(&self, tcx: TyCtxt<'_>) -> Span;
599 impl Locatable for Span {
600 fn to_span(&self, _: TyCtxt<'_>) -> Span {
605 impl Locatable for DefIndex {
606 fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
607 let hir_id = tcx.hir().def_index_to_hir_id(*self);
608 tcx.hir().span(hir_id)
612 impl Locatable for hir::HirId {
613 fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
614 tcx.hir().span(*self)
618 ///////////////////////////////////////////////////////////////////////////
619 // The Resolver. This is the type folding engine that detects
620 // unresolved types and so forth.
622 struct Resolver<'cx, 'tcx> {
624 infcx: &'cx InferCtxt<'cx, 'tcx>,
625 span: &'cx dyn Locatable,
626 body: &'tcx hir::Body<'tcx>,
629 impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
631 fcx: &'cx FnCtxt<'cx, 'tcx>,
632 span: &'cx dyn Locatable,
633 body: &'tcx hir::Body<'tcx>,
634 ) -> Resolver<'cx, 'tcx> {
635 Resolver { tcx: fcx.tcx, infcx: fcx, span, body }
638 fn report_error(&self, t: Ty<'tcx>) {
639 if !self.tcx.sess.has_errors() {
641 .need_type_info_err(Some(self.body.id()), self.span.to_span(self.tcx), t, E0282)
647 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
648 fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
652 fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
653 match self.infcx.fully_resolve(&t) {
656 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable", t);
657 self.report_error(t);
663 // FIXME This should be carefully checked
664 // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
665 fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
666 self.infcx.fully_resolve(&r).unwrap_or(self.tcx.lifetimes.re_static)
669 fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
670 match self.infcx.fully_resolve(&ct) {
673 debug!("Resolver::fold_const: input const `{:?}` not fully resolvable", ct);
674 // FIXME: we'd like to use `self.report_error`, but it doesn't yet
675 // accept a &'tcx ty::Const.
676 self.tcx().consts.err
682 ///////////////////////////////////////////////////////////////////////////
683 // During type check, we store promises with the result of trait
684 // lookup rather than the actual results (because the results are not
685 // necessarily available immediately). These routines unwind the
686 // promises. It is expected that we will have already reported any
687 // errors that may be encountered, so if the promises store an error,
688 // a dummy result is returned.