rustc_hir_typeck/
writeback.rs

1//! During type inference, partially inferred terms are
2//! represented using inference variables (ty::Infer). These don't appear in
3//! the final [`ty::TypeckResults`] since all of the types should have been
4//! inferred once typeck is done.
5//!
6//! When type inference is running however, having to update the typeck results
7//! every time a new type is inferred would be unreasonably slow, so instead all
8//! of the replacement happens at the end in [`FnCtxt::resolve_type_vars_in_body`],
9//! which creates a new `TypeckResults` which doesn't contain any inference variables.
10
11use std::mem;
12use std::ops::ControlFlow;
13
14use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
15use rustc_data_structures::unord::ExtendUnord;
16use rustc_errors::{E0720, ErrorGuaranteed};
17use rustc_hir::def_id::LocalDefId;
18use rustc_hir::intravisit::{self, InferKind, Visitor};
19use rustc_hir::{self as hir, AmbigArg, HirId};
20use rustc_infer::traits::solve::Goal;
21use rustc_middle::traits::ObligationCause;
22use rustc_middle::ty::adjustment::{Adjust, Adjustment, PointerCoercion};
23use rustc_middle::ty::{
24    self, DefiningScopeKind, OpaqueHiddenType, Ty, TyCtxt, TypeFoldable, TypeFolder,
25    TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
26    fold_regions,
27};
28use rustc_span::{Span, sym};
29use rustc_trait_selection::error_reporting::infer::need_type_info::TypeAnnotationNeeded;
30use rustc_trait_selection::opaque_types::check_opaque_type_parameter_valid;
31use rustc_trait_selection::solve;
32use tracing::{debug, instrument};
33
34use crate::FnCtxt;
35
36///////////////////////////////////////////////////////////////////////////
37// Entry point
38
39impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
40    pub(crate) fn resolve_type_vars_in_body(
41        &self,
42        body: &'tcx hir::Body<'tcx>,
43    ) -> &'tcx ty::TypeckResults<'tcx> {
44        let item_def_id = self.tcx.hir_body_owner_def_id(body.id());
45
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_args = self.tcx.has_attr(item_def_id, sym::rustc_dump_user_args);
49
50        let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_args);
51        for param in body.params {
52            wbcx.visit_node_id(param.pat.span, param.hir_id);
53        }
54        match self.tcx.hir_body_owner_kind(item_def_id) {
55            // Visit the type of a const or static, which is used during THIR building.
56            hir::BodyOwnerKind::Const { .. }
57            | hir::BodyOwnerKind::Static(_)
58            | hir::BodyOwnerKind::GlobalAsm => {
59                let item_hir_id = self.tcx.local_def_id_to_hir_id(item_def_id);
60                wbcx.visit_node_id(body.value.span, item_hir_id);
61            }
62            // For closures and consts, we already plan to visit liberated signatures.
63            hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => {}
64        }
65        wbcx.visit_body(body);
66        wbcx.visit_min_capture_map();
67        wbcx.eval_closure_size();
68        wbcx.visit_fake_reads_map();
69        wbcx.visit_closures();
70        wbcx.visit_liberated_fn_sigs();
71        wbcx.visit_fru_field_types();
72        wbcx.visit_opaque_types();
73        wbcx.visit_coercion_casts();
74        wbcx.visit_user_provided_tys();
75        wbcx.visit_user_provided_sigs();
76        wbcx.visit_coroutine_interior();
77        wbcx.visit_offset_of_container_types();
78
79        wbcx.typeck_results.rvalue_scopes =
80            mem::take(&mut self.typeck_results.borrow_mut().rvalue_scopes);
81
82        let used_trait_imports =
83            mem::take(&mut self.typeck_results.borrow_mut().used_trait_imports);
84        debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
85        wbcx.typeck_results.used_trait_imports = used_trait_imports;
86
87        debug!("writeback: typeck results for {:?} are {:#?}", item_def_id, wbcx.typeck_results);
88
89        self.tcx.arena.alloc(wbcx.typeck_results)
90    }
91}
92
93/// The Writeback context. This visitor walks the HIR, checking the
94/// fn-specific typeck results to find inference variables. It resolves
95/// those inference variables and writes the final result into the
96/// `TypeckResults`. It also applies a few ad-hoc checks that were not
97/// convenient to do elsewhere.
98struct WritebackCx<'cx, 'tcx> {
99    fcx: &'cx FnCtxt<'cx, 'tcx>,
100
101    typeck_results: ty::TypeckResults<'tcx>,
102
103    body: &'tcx hir::Body<'tcx>,
104
105    rustc_dump_user_args: bool,
106}
107
108impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
109    fn new(
110        fcx: &'cx FnCtxt<'cx, 'tcx>,
111        body: &'tcx hir::Body<'tcx>,
112        rustc_dump_user_args: bool,
113    ) -> WritebackCx<'cx, 'tcx> {
114        let owner = body.id().hir_id.owner;
115
116        let mut wbcx = WritebackCx {
117            fcx,
118            typeck_results: ty::TypeckResults::new(owner),
119            body,
120            rustc_dump_user_args,
121        };
122
123        // HACK: We specifically don't want the (opaque) error from tainting our
124        // inference context. That'll prevent us from doing opaque type inference
125        // later on in borrowck, which affects diagnostic spans pretty negatively.
126        if let Some(e) = fcx.tainted_by_errors() {
127            wbcx.typeck_results.tainted_by_errors = Some(e);
128        }
129
130        wbcx
131    }
132
133    fn tcx(&self) -> TyCtxt<'tcx> {
134        self.fcx.tcx
135    }
136
137    fn write_ty_to_typeck_results(&mut self, hir_id: HirId, ty: Ty<'tcx>) {
138        debug!("write_ty_to_typeck_results({:?}, {:?})", hir_id, ty);
139        assert!(
140            !ty.has_infer() && !ty.has_placeholders() && !ty.has_free_regions(),
141            "{ty} can't be put into typeck results"
142        );
143        self.typeck_results.node_types_mut().insert(hir_id, ty);
144    }
145
146    // Hacky hack: During type-checking, we treat *all* operators
147    // as potentially overloaded. But then, during writeback, if
148    // we observe that something like `a+b` is (known to be)
149    // operating on scalars, we clear the overload.
150    fn fix_scalar_builtin_expr(&mut self, e: &hir::Expr<'_>) {
151        match e.kind {
152            hir::ExprKind::Unary(hir::UnOp::Neg | hir::UnOp::Not, inner) => {
153                let inner_ty = self.typeck_results.node_type(inner.hir_id);
154
155                if inner_ty.is_scalar() {
156                    self.typeck_results.type_dependent_defs_mut().remove(e.hir_id);
157                    self.typeck_results.node_args_mut().remove(e.hir_id);
158                }
159            }
160            hir::ExprKind::Binary(ref op, lhs, rhs) => {
161                let lhs_ty = self.typeck_results.node_type(lhs.hir_id);
162                let rhs_ty = self.typeck_results.node_type(rhs.hir_id);
163
164                if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
165                    self.typeck_results.type_dependent_defs_mut().remove(e.hir_id);
166                    self.typeck_results.node_args_mut().remove(e.hir_id);
167
168                    if !op.node.is_by_value() {
169                        let mut adjustments = self.typeck_results.adjustments_mut();
170                        if let Some(a) = adjustments.get_mut(lhs.hir_id) {
171                            a.pop();
172                        }
173                        if let Some(a) = adjustments.get_mut(rhs.hir_id) {
174                            a.pop();
175                        }
176                    }
177                }
178            }
179            hir::ExprKind::AssignOp(_, lhs, rhs) => {
180                let lhs_ty = self.typeck_results.node_type(lhs.hir_id);
181                let rhs_ty = self.typeck_results.node_type(rhs.hir_id);
182
183                if lhs_ty.is_scalar() && rhs_ty.is_scalar() {
184                    self.typeck_results.type_dependent_defs_mut().remove(e.hir_id);
185                    self.typeck_results.node_args_mut().remove(e.hir_id);
186
187                    if let Some(a) = self.typeck_results.adjustments_mut().get_mut(lhs.hir_id) {
188                        a.pop();
189                    }
190                }
191            }
192            _ => {}
193        }
194    }
195
196    // (ouz-a 1005988): Normally `[T] : std::ops::Index<usize>` should be normalized
197    // into [T] but currently `Where` clause stops the normalization process for it,
198    // here we compare types of expr and base in a code without `Where` clause they would be equal
199    // if they are not we don't modify the expr, hence we bypass the ICE
200    fn is_builtin_index(
201        &mut self,
202        e: &hir::Expr<'_>,
203        base_ty: Ty<'tcx>,
204        index_ty: Ty<'tcx>,
205    ) -> bool {
206        if let Some(elem_ty) = base_ty.builtin_index()
207            && let Some(exp_ty) = self.typeck_results.expr_ty_opt(e)
208        {
209            elem_ty == exp_ty && index_ty == self.fcx.tcx.types.usize
210        } else {
211            false
212        }
213    }
214
215    // Similar to operators, indexing is always assumed to be overloaded
216    // Here, correct cases where an indexing expression can be simplified
217    // to use builtin indexing because the index type is known to be
218    // usize-ish
219    fn fix_index_builtin_expr(&mut self, e: &hir::Expr<'_>) {
220        if let hir::ExprKind::Index(ref base, ref index, _) = e.kind {
221            // All valid indexing looks like this; might encounter non-valid indexes at this point.
222            let base_ty = self.typeck_results.expr_ty_adjusted(base);
223            if let ty::Ref(_, base_ty_inner, _) = *base_ty.kind() {
224                let index_ty = self.typeck_results.expr_ty_adjusted(index);
225                if self.is_builtin_index(e, base_ty_inner, index_ty) {
226                    // Remove the method call record
227                    self.typeck_results.type_dependent_defs_mut().remove(e.hir_id);
228                    self.typeck_results.node_args_mut().remove(e.hir_id);
229
230                    if let Some(a) = self.typeck_results.adjustments_mut().get_mut(base.hir_id) {
231                        // Discard the need for a mutable borrow
232
233                        // Extra adjustment made when indexing causes a drop
234                        // of size information - we need to get rid of it
235                        // Since this is "after" the other adjustment to be
236                        // discarded, we do an extra `pop()`
237                        if let Some(Adjustment {
238                            kind: Adjust::Pointer(PointerCoercion::Unsize),
239                            ..
240                        }) = a.pop()
241                        {
242                            // So the borrow discard actually happens here
243                            a.pop();
244                        }
245                    }
246                }
247            }
248        }
249    }
250}
251
252///////////////////////////////////////////////////////////////////////////
253// Impl of Visitor for Resolver
254//
255// This is the master code which walks the AST. It delegates most of
256// the heavy lifting to the generic visit and resolve functions
257// below. In general, a function is made into a `visitor` if it must
258// traffic in node-ids or update typeck results in the type context etc.
259
260impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
261    fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
262        match e.kind {
263            hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
264                let body = self.fcx.tcx.hir_body(body);
265                for param in body.params {
266                    self.visit_node_id(e.span, param.hir_id);
267                }
268
269                self.visit_body(body);
270            }
271            hir::ExprKind::Struct(_, fields, _) => {
272                for field in fields {
273                    self.visit_field_id(field.hir_id);
274                }
275            }
276            hir::ExprKind::Field(..) | hir::ExprKind::OffsetOf(..) => {
277                self.visit_field_id(e.hir_id);
278            }
279            _ => {}
280        }
281
282        self.visit_node_id(e.span, e.hir_id);
283        intravisit::walk_expr(self, e);
284
285        self.fix_scalar_builtin_expr(e);
286        self.fix_index_builtin_expr(e);
287    }
288
289    fn visit_inline_const(&mut self, anon_const: &hir::ConstBlock) {
290        let span = self.tcx().def_span(anon_const.def_id);
291        self.visit_node_id(span, anon_const.hir_id);
292
293        let body = self.tcx().hir_body(anon_const.body);
294        self.visit_body(body);
295    }
296
297    fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
298        match &p.kind {
299            hir::GenericParamKind::Lifetime { .. } => {
300                // Nothing to write back here
301            }
302            hir::GenericParamKind::Type { .. } | hir::GenericParamKind::Const { .. } => {
303                self.tcx()
304                    .dcx()
305                    .span_delayed_bug(p.span, format!("unexpected generic param: {p:?}"));
306            }
307        }
308    }
309
310    fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
311        self.visit_node_id(b.span, b.hir_id);
312        intravisit::walk_block(self, b);
313    }
314
315    fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
316        match p.kind {
317            hir::PatKind::Binding(..) => {
318                let typeck_results = self.fcx.typeck_results.borrow();
319                let bm = typeck_results.extract_binding_mode(self.tcx().sess, p.hir_id, p.span);
320                self.typeck_results.pat_binding_modes_mut().insert(p.hir_id, bm);
321            }
322            hir::PatKind::Struct(_, fields, _) => {
323                for field in fields {
324                    self.visit_field_id(field.hir_id);
325                }
326            }
327            _ => {}
328        };
329
330        self.visit_rust_2024_migration_desugared_pats(p.hir_id);
331        self.visit_skipped_ref_pats(p.hir_id);
332        self.visit_pat_adjustments(p.span, p.hir_id);
333
334        self.visit_node_id(p.span, p.hir_id);
335        intravisit::walk_pat(self, p);
336    }
337
338    fn visit_pat_expr(&mut self, expr: &'tcx hir::PatExpr<'tcx>) {
339        self.visit_node_id(expr.span, expr.hir_id);
340        intravisit::walk_pat_expr(self, expr);
341    }
342
343    fn visit_local(&mut self, l: &'tcx hir::LetStmt<'tcx>) {
344        intravisit::walk_local(self, l);
345        let var_ty = self.fcx.local_ty(l.span, l.hir_id);
346        let var_ty = self.resolve(var_ty, &l.span);
347        self.write_ty_to_typeck_results(l.hir_id, var_ty);
348    }
349
350    fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx, AmbigArg>) {
351        intravisit::walk_ty(self, hir_ty);
352        // If there are type checking errors, Type privacy pass will stop,
353        // so we may not get the type from hid_id, see #104513
354        if let Some(ty) = self.fcx.node_ty_opt(hir_ty.hir_id) {
355            let ty = self.resolve(ty, &hir_ty.span);
356            self.write_ty_to_typeck_results(hir_ty.hir_id, ty);
357        }
358    }
359
360    fn visit_infer(
361        &mut self,
362        inf_id: HirId,
363        inf_span: Span,
364        _kind: InferKind<'cx>,
365    ) -> Self::Result {
366        self.visit_id(inf_id);
367
368        // We don't currently write inference results of const infer vars to
369        // the typeck results as there is not yet any part of the compiler that
370        // needs this information.
371        if let Some(ty) = self.fcx.node_ty_opt(inf_id) {
372            let ty = self.resolve(ty, &inf_span);
373            self.write_ty_to_typeck_results(inf_id, ty);
374        }
375    }
376}
377
378impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
379    fn eval_closure_size(&mut self) {
380        self.tcx().with_stable_hashing_context(|ref hcx| {
381            let fcx_typeck_results = self.fcx.typeck_results.borrow();
382
383            self.typeck_results.closure_size_eval = fcx_typeck_results
384                .closure_size_eval
385                .to_sorted(hcx, false)
386                .into_iter()
387                .map(|(&closure_def_id, data)| {
388                    let closure_hir_id = self.tcx().local_def_id_to_hir_id(closure_def_id);
389                    let data = self.resolve(*data, &closure_hir_id);
390                    (closure_def_id, data)
391                })
392                .collect();
393        })
394    }
395
396    fn visit_min_capture_map(&mut self) {
397        self.tcx().with_stable_hashing_context(|ref hcx| {
398            let fcx_typeck_results = self.fcx.typeck_results.borrow();
399
400            self.typeck_results.closure_min_captures = fcx_typeck_results
401                .closure_min_captures
402                .to_sorted(hcx, false)
403                .into_iter()
404                .map(|(&closure_def_id, root_min_captures)| {
405                    let root_var_map_wb = root_min_captures
406                        .iter()
407                        .map(|(var_hir_id, min_list)| {
408                            let min_list_wb = min_list
409                                .iter()
410                                .map(|captured_place| {
411                                    let locatable =
412                                        captured_place.info.path_expr_id.unwrap_or_else(|| {
413                                            self.tcx().local_def_id_to_hir_id(closure_def_id)
414                                        });
415                                    self.resolve(captured_place.clone(), &locatable)
416                                })
417                                .collect();
418                            (*var_hir_id, min_list_wb)
419                        })
420                        .collect();
421                    (closure_def_id, root_var_map_wb)
422                })
423                .collect();
424        })
425    }
426
427    fn visit_fake_reads_map(&mut self) {
428        self.tcx().with_stable_hashing_context(move |ref hcx| {
429            let fcx_typeck_results = self.fcx.typeck_results.borrow();
430
431            self.typeck_results.closure_fake_reads = fcx_typeck_results
432                .closure_fake_reads
433                .to_sorted(hcx, true)
434                .into_iter()
435                .map(|(&closure_def_id, fake_reads)| {
436                    let resolved_fake_reads = fake_reads
437                        .iter()
438                        .map(|(place, cause, hir_id)| {
439                            let locatable = self.tcx().local_def_id_to_hir_id(closure_def_id);
440                            let resolved_fake_read = self.resolve(place.clone(), &locatable);
441                            (resolved_fake_read, *cause, *hir_id)
442                        })
443                        .collect();
444
445                    (closure_def_id, resolved_fake_reads)
446                })
447                .collect();
448        });
449    }
450
451    fn visit_closures(&mut self) {
452        let fcx_typeck_results = self.fcx.typeck_results.borrow();
453        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
454        let common_hir_owner = fcx_typeck_results.hir_owner;
455
456        let fcx_closure_kind_origins =
457            fcx_typeck_results.closure_kind_origins().items_in_stable_order();
458
459        for (local_id, origin) in fcx_closure_kind_origins {
460            let hir_id = HirId { owner: common_hir_owner, local_id };
461            let place_span = origin.0;
462            let place = self.resolve(origin.1.clone(), &place_span);
463            self.typeck_results.closure_kind_origins_mut().insert(hir_id, (place_span, place));
464        }
465    }
466
467    fn visit_coercion_casts(&mut self) {
468        let fcx_typeck_results = self.fcx.typeck_results.borrow();
469
470        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
471
472        let fcx_coercion_casts = fcx_typeck_results.coercion_casts().to_sorted_stable_ord();
473        for &local_id in fcx_coercion_casts {
474            self.typeck_results.set_coercion_cast(local_id);
475        }
476    }
477
478    fn visit_user_provided_tys(&mut self) {
479        let fcx_typeck_results = self.fcx.typeck_results.borrow();
480        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
481        let common_hir_owner = fcx_typeck_results.hir_owner;
482
483        if self.rustc_dump_user_args {
484            let sorted_user_provided_types =
485                fcx_typeck_results.user_provided_types().items_in_stable_order();
486
487            let mut errors_buffer = Vec::new();
488            for (local_id, c_ty) in sorted_user_provided_types {
489                let hir_id = HirId { owner: common_hir_owner, local_id };
490
491                if let ty::UserTypeKind::TypeOf(_, user_args) = c_ty.value.kind {
492                    // This is a unit-testing mechanism.
493                    let span = self.tcx().hir_span(hir_id);
494                    // We need to buffer the errors in order to guarantee a consistent
495                    // order when emitting them.
496                    let err =
497                        self.tcx().dcx().struct_span_err(span, format!("user args: {user_args:?}"));
498                    errors_buffer.push(err);
499                }
500            }
501
502            if !errors_buffer.is_empty() {
503                errors_buffer.sort_by_key(|diag| diag.span.primary_span());
504                for err in errors_buffer {
505                    err.emit();
506                }
507            }
508        }
509
510        self.typeck_results.user_provided_types_mut().extend(
511            fcx_typeck_results.user_provided_types().items().map(|(local_id, c_ty)| {
512                let hir_id = HirId { owner: common_hir_owner, local_id };
513                (hir_id, *c_ty)
514            }),
515        );
516    }
517
518    fn visit_user_provided_sigs(&mut self) {
519        let fcx_typeck_results = self.fcx.typeck_results.borrow();
520        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
521
522        self.typeck_results.user_provided_sigs.extend_unord(
523            fcx_typeck_results.user_provided_sigs.items().map(|(def_id, c_sig)| (*def_id, *c_sig)),
524        );
525    }
526
527    fn visit_coroutine_interior(&mut self) {
528        let fcx_typeck_results = self.fcx.typeck_results.borrow();
529        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
530        for (predicate, cause) in &fcx_typeck_results.coroutine_stalled_predicates {
531            let (predicate, cause) =
532                self.resolve_coroutine_predicate((*predicate, cause.clone()), &cause.span);
533            self.typeck_results.coroutine_stalled_predicates.insert((predicate, cause));
534        }
535    }
536
537    #[instrument(skip(self), level = "debug")]
538    fn visit_opaque_types(&mut self) {
539        let tcx = self.tcx();
540        // We clone the opaques instead of stealing them here as they are still used for
541        // normalization in the next generation trait solver.
542        let opaque_types = self.fcx.infcx.clone_opaque_types();
543        let num_entries = self.fcx.inner.borrow_mut().opaque_types().num_entries();
544        let prev = self.fcx.checked_opaque_types_storage_entries.replace(Some(num_entries));
545        debug_assert_eq!(prev, None);
546        for (opaque_type_key, hidden_type) in opaque_types {
547            let hidden_type = self.resolve(hidden_type, &hidden_type.span);
548            let opaque_type_key = self.resolve(opaque_type_key, &hidden_type.span);
549
550            if !self.fcx.next_trait_solver() {
551                if let ty::Alias(ty::Opaque, alias_ty) = hidden_type.ty.kind()
552                    && alias_ty.def_id == opaque_type_key.def_id.to_def_id()
553                    && alias_ty.args == opaque_type_key.args
554                {
555                    continue;
556                }
557            }
558
559            if let Err(err) = check_opaque_type_parameter_valid(
560                &self.fcx,
561                opaque_type_key,
562                hidden_type.span,
563                DefiningScopeKind::HirTypeck,
564            ) {
565                self.typeck_results.concrete_opaque_types.insert(
566                    opaque_type_key.def_id,
567                    ty::OpaqueHiddenType::new_error(tcx, err.report(self.fcx)),
568                );
569            }
570
571            let hidden_type = hidden_type.remap_generic_params_to_declaration_params(
572                opaque_type_key,
573                tcx,
574                DefiningScopeKind::HirTypeck,
575            );
576
577            if let Some(prev) = self
578                .typeck_results
579                .concrete_opaque_types
580                .insert(opaque_type_key.def_id, hidden_type)
581            {
582                let entry = &mut self
583                    .typeck_results
584                    .concrete_opaque_types
585                    .get_mut(&opaque_type_key.def_id)
586                    .unwrap();
587                if prev.ty != hidden_type.ty {
588                    if let Some(guar) = self.typeck_results.tainted_by_errors {
589                        entry.ty = Ty::new_error(tcx, guar);
590                    } else {
591                        let (Ok(guar) | Err(guar)) =
592                            prev.build_mismatch_error(&hidden_type, tcx).map(|d| d.emit());
593                        entry.ty = Ty::new_error(tcx, guar);
594                    }
595                }
596
597                // Pick a better span if there is one.
598                // FIXME(oli-obk): collect multiple spans for better diagnostics down the road.
599                entry.span = prev.span.substitute_dummy(hidden_type.span);
600            }
601        }
602
603        let recursive_opaques: Vec<_> = self
604            .typeck_results
605            .concrete_opaque_types
606            .iter()
607            .filter(|&(&def_id, hidden_ty)| {
608                hidden_ty
609                    .ty
610                    .visit_with(&mut HasRecursiveOpaque {
611                        def_id,
612                        seen: Default::default(),
613                        opaques: &self.typeck_results.concrete_opaque_types,
614                        tcx,
615                    })
616                    .is_break()
617            })
618            .map(|(def_id, hidden_ty)| (*def_id, hidden_ty.span))
619            .collect();
620        for (def_id, span) in recursive_opaques {
621            let guar = self
622                .fcx
623                .dcx()
624                .struct_span_err(span, "cannot resolve opaque type")
625                .with_code(E0720)
626                .emit();
627            self.typeck_results
628                .concrete_opaque_types
629                .insert(def_id, OpaqueHiddenType { span, ty: Ty::new_error(tcx, guar) });
630        }
631    }
632
633    fn visit_field_id(&mut self, hir_id: HirId) {
634        if let Some(index) = self.fcx.typeck_results.borrow_mut().field_indices_mut().remove(hir_id)
635        {
636            self.typeck_results.field_indices_mut().insert(hir_id, index);
637        }
638    }
639
640    #[instrument(skip(self, span), level = "debug")]
641    fn visit_node_id(&mut self, span: Span, hir_id: HirId) {
642        // Export associated path extensions and method resolutions.
643        if let Some(def) =
644            self.fcx.typeck_results.borrow_mut().type_dependent_defs_mut().remove(hir_id)
645        {
646            self.typeck_results.type_dependent_defs_mut().insert(hir_id, def);
647        }
648
649        // Resolve any borrowings for the node with id `node_id`
650        self.visit_adjustments(span, hir_id);
651
652        // Resolve the type of the node with id `node_id`
653        let n_ty = self.fcx.node_ty(hir_id);
654        let n_ty = self.resolve(n_ty, &span);
655        self.write_ty_to_typeck_results(hir_id, n_ty);
656        debug!(?n_ty);
657
658        // Resolve any generic parameters
659        if let Some(args) = self.fcx.typeck_results.borrow().node_args_opt(hir_id) {
660            let args = self.resolve(args, &span);
661            debug!("write_args_to_tcx({:?}, {:?})", hir_id, args);
662            assert!(!args.has_infer() && !args.has_placeholders());
663            self.typeck_results.node_args_mut().insert(hir_id, args);
664        }
665    }
666
667    #[instrument(skip(self, span), level = "debug")]
668    fn visit_adjustments(&mut self, span: Span, hir_id: HirId) {
669        let adjustment = self.fcx.typeck_results.borrow_mut().adjustments_mut().remove(hir_id);
670        match adjustment {
671            None => {
672                debug!("no adjustments for node");
673            }
674
675            Some(adjustment) => {
676                let resolved_adjustment = self.resolve(adjustment, &span);
677                debug!(?resolved_adjustment);
678                self.typeck_results.adjustments_mut().insert(hir_id, resolved_adjustment);
679            }
680        }
681    }
682
683    #[instrument(skip(self), level = "debug")]
684    fn visit_rust_2024_migration_desugared_pats(&mut self, hir_id: hir::HirId) {
685        if let Some(is_hard_error) = self
686            .fcx
687            .typeck_results
688            .borrow_mut()
689            .rust_2024_migration_desugared_pats_mut()
690            .remove(hir_id)
691        {
692            debug!(
693                "node is a pat whose match ergonomics are desugared by the Rust 2024 migration lint"
694            );
695            self.typeck_results
696                .rust_2024_migration_desugared_pats_mut()
697                .insert(hir_id, is_hard_error);
698        }
699    }
700
701    #[instrument(skip(self, span), level = "debug")]
702    fn visit_pat_adjustments(&mut self, span: Span, hir_id: HirId) {
703        let adjustment = self.fcx.typeck_results.borrow_mut().pat_adjustments_mut().remove(hir_id);
704        match adjustment {
705            None => {
706                debug!("no pat_adjustments for node");
707            }
708
709            Some(adjustment) => {
710                let resolved_adjustment = self.resolve(adjustment, &span);
711                debug!(?resolved_adjustment);
712                self.typeck_results.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
713            }
714        }
715    }
716
717    #[instrument(skip(self), level = "debug")]
718    fn visit_skipped_ref_pats(&mut self, hir_id: hir::HirId) {
719        if self.fcx.typeck_results.borrow_mut().skipped_ref_pats_mut().remove(hir_id) {
720            debug!("node is a skipped ref pat");
721            self.typeck_results.skipped_ref_pats_mut().insert(hir_id);
722        }
723    }
724
725    fn visit_liberated_fn_sigs(&mut self) {
726        let fcx_typeck_results = self.fcx.typeck_results.borrow();
727        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
728        let common_hir_owner = fcx_typeck_results.hir_owner;
729
730        let fcx_liberated_fn_sigs = fcx_typeck_results.liberated_fn_sigs().items_in_stable_order();
731
732        for (local_id, &fn_sig) in fcx_liberated_fn_sigs {
733            let hir_id = HirId { owner: common_hir_owner, local_id };
734            let fn_sig = self.resolve(fn_sig, &hir_id);
735            self.typeck_results.liberated_fn_sigs_mut().insert(hir_id, fn_sig);
736        }
737    }
738
739    fn visit_fru_field_types(&mut self) {
740        let fcx_typeck_results = self.fcx.typeck_results.borrow();
741        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
742        let common_hir_owner = fcx_typeck_results.hir_owner;
743
744        let fcx_fru_field_types = fcx_typeck_results.fru_field_types().items_in_stable_order();
745
746        for (local_id, ftys) in fcx_fru_field_types {
747            let hir_id = HirId { owner: common_hir_owner, local_id };
748            let ftys = self.resolve(ftys.clone(), &hir_id);
749            self.typeck_results.fru_field_types_mut().insert(hir_id, ftys);
750        }
751    }
752
753    fn visit_offset_of_container_types(&mut self) {
754        let fcx_typeck_results = self.fcx.typeck_results.borrow();
755        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
756        let common_hir_owner = fcx_typeck_results.hir_owner;
757
758        for (local_id, &(container, ref indices)) in
759            fcx_typeck_results.offset_of_data().items_in_stable_order()
760        {
761            let hir_id = HirId { owner: common_hir_owner, local_id };
762            let container = self.resolve(container, &hir_id);
763            self.typeck_results.offset_of_data_mut().insert(hir_id, (container, indices.clone()));
764        }
765    }
766
767    fn resolve<T>(&mut self, value: T, span: &dyn Locatable) -> T
768    where
769        T: TypeFoldable<TyCtxt<'tcx>>,
770    {
771        let value = self.fcx.resolve_vars_if_possible(value);
772
773        let mut goals = vec![];
774        let value =
775            value.fold_with(&mut Resolver::new(self.fcx, span, self.body, true, &mut goals));
776
777        // Ensure that we resolve goals we get from normalizing coroutine interiors,
778        // but we shouldn't expect those goals to need normalizing (or else we'd get
779        // into a somewhat awkward fixpoint situation, and we don't need it anyways).
780        let mut unexpected_goals = vec![];
781        self.typeck_results.coroutine_stalled_predicates.extend(
782            goals
783                .into_iter()
784                .map(|pred| {
785                    self.fcx.resolve_vars_if_possible(pred).fold_with(&mut Resolver::new(
786                        self.fcx,
787                        span,
788                        self.body,
789                        false,
790                        &mut unexpected_goals,
791                    ))
792                })
793                // FIXME: throwing away the param-env :(
794                .map(|goal| (goal.predicate, self.fcx.misc(span.to_span(self.fcx.tcx)))),
795        );
796        assert_eq!(unexpected_goals, vec![]);
797
798        assert!(!value.has_infer());
799
800        // We may have introduced e.g. `ty::Error`, if inference failed, make sure
801        // to mark the `TypeckResults` as tainted in that case, so that downstream
802        // users of the typeck results don't produce extra errors, or worse, ICEs.
803        if let Err(guar) = value.error_reported() {
804            self.typeck_results.tainted_by_errors = Some(guar);
805        }
806
807        value
808    }
809
810    fn resolve_coroutine_predicate<T>(&mut self, value: T, span: &dyn Locatable) -> T
811    where
812        T: TypeFoldable<TyCtxt<'tcx>>,
813    {
814        let value = self.fcx.resolve_vars_if_possible(value);
815
816        let mut goals = vec![];
817        let value =
818            value.fold_with(&mut Resolver::new(self.fcx, span, self.body, false, &mut goals));
819        assert_eq!(goals, vec![]);
820
821        assert!(!value.has_infer());
822
823        // We may have introduced e.g. `ty::Error`, if inference failed, make sure
824        // to mark the `TypeckResults` as tainted in that case, so that downstream
825        // users of the typeck results don't produce extra errors, or worse, ICEs.
826        if let Err(guar) = value.error_reported() {
827            self.typeck_results.tainted_by_errors = Some(guar);
828        }
829
830        value
831    }
832}
833
834pub(crate) trait Locatable {
835    fn to_span(&self, tcx: TyCtxt<'_>) -> Span;
836}
837
838impl Locatable for Span {
839    fn to_span(&self, _: TyCtxt<'_>) -> Span {
840        *self
841    }
842}
843
844impl Locatable for HirId {
845    fn to_span(&self, tcx: TyCtxt<'_>) -> Span {
846        tcx.hir_span(*self)
847    }
848}
849
850struct Resolver<'cx, 'tcx> {
851    fcx: &'cx FnCtxt<'cx, 'tcx>,
852    span: &'cx dyn Locatable,
853    body: &'tcx hir::Body<'tcx>,
854    /// Whether we should normalize using the new solver, disabled
855    /// both when using the old solver and when resolving predicates.
856    should_normalize: bool,
857    nested_goals: &'cx mut Vec<Goal<'tcx, ty::Predicate<'tcx>>>,
858}
859
860impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
861    fn new(
862        fcx: &'cx FnCtxt<'cx, 'tcx>,
863        span: &'cx dyn Locatable,
864        body: &'tcx hir::Body<'tcx>,
865        should_normalize: bool,
866        nested_goals: &'cx mut Vec<Goal<'tcx, ty::Predicate<'tcx>>>,
867    ) -> Resolver<'cx, 'tcx> {
868        Resolver { fcx, span, body, nested_goals, should_normalize }
869    }
870
871    fn report_error(&self, p: impl Into<ty::Term<'tcx>>) -> ErrorGuaranteed {
872        if let Some(guar) = self.fcx.tainted_by_errors() {
873            guar
874        } else {
875            self.fcx
876                .err_ctxt()
877                .emit_inference_failure_err(
878                    self.fcx.tcx.hir_body_owner_def_id(self.body.id()),
879                    self.span.to_span(self.fcx.tcx),
880                    p.into(),
881                    TypeAnnotationNeeded::E0282,
882                    false,
883                )
884                .emit()
885        }
886    }
887
888    fn handle_term<T>(
889        &mut self,
890        value: T,
891        outer_exclusive_binder: impl FnOnce(T) -> ty::DebruijnIndex,
892        new_err: impl Fn(TyCtxt<'tcx>, ErrorGuaranteed) -> T,
893    ) -> T
894    where
895        T: Into<ty::Term<'tcx>> + TypeSuperFoldable<TyCtxt<'tcx>> + Copy,
896    {
897        let tcx = self.fcx.tcx;
898        // We must deeply normalize in the new solver, since later lints expect
899        // that types that show up in the typeck are fully normalized.
900        let mut value = if self.should_normalize && self.fcx.next_trait_solver() {
901            let body_id = tcx.hir_body_owner_def_id(self.body.id());
902            let cause = ObligationCause::misc(self.span.to_span(tcx), body_id);
903            let at = self.fcx.at(&cause, self.fcx.param_env);
904            let universes = vec![None; outer_exclusive_binder(value).as_usize()];
905            match solve::deeply_normalize_with_skipped_universes_and_ambiguous_coroutine_goals(
906                at, value, universes,
907            ) {
908                Ok((value, goals)) => {
909                    self.nested_goals.extend(goals);
910                    value
911                }
912                Err(errors) => {
913                    let guar = self.fcx.err_ctxt().report_fulfillment_errors(errors);
914                    new_err(tcx, guar)
915                }
916            }
917        } else {
918            value
919        };
920
921        // Bail if there are any non-region infer.
922        if value.has_non_region_infer() {
923            let guar = self.report_error(value);
924            value = new_err(tcx, guar);
925        }
926
927        // Erase the regions from the ty, since it's not really meaningful what
928        // these region values are; there's not a trivial correspondence between
929        // regions in the HIR and MIR, so when we turn the body into MIR, there's
930        // no reason to keep regions around. They will be repopulated during MIR
931        // borrowck, and specifically region constraints will be populated during
932        // MIR typeck which is run on the new body.
933        //
934        // We're not using `tcx.erase_regions` as that also anonymizes bound variables,
935        // regressing borrowck diagnostics.
936        value = fold_regions(tcx, value, |_, _| tcx.lifetimes.re_erased);
937
938        // Normalize consts in writeback, because GCE doesn't normalize eagerly.
939        if tcx.features().generic_const_exprs() {
940            value = value.fold_with(&mut EagerlyNormalizeConsts::new(self.fcx));
941        }
942
943        value
944    }
945}
946
947impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Resolver<'cx, 'tcx> {
948    fn cx(&self) -> TyCtxt<'tcx> {
949        self.fcx.tcx
950    }
951
952    fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
953        debug_assert!(!r.is_bound(), "Should not be resolving bound region.");
954        self.fcx.tcx.lifetimes.re_erased
955    }
956
957    fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
958        self.handle_term(ty, Ty::outer_exclusive_binder, Ty::new_error)
959    }
960
961    fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
962        self.handle_term(ct, ty::Const::outer_exclusive_binder, ty::Const::new_error)
963    }
964
965    fn fold_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
966        assert!(
967            !self.should_normalize,
968            "normalizing predicates in writeback is not generally sound"
969        );
970        predicate.super_fold_with(self)
971    }
972}
973
974struct EagerlyNormalizeConsts<'tcx> {
975    tcx: TyCtxt<'tcx>,
976    typing_env: ty::TypingEnv<'tcx>,
977}
978impl<'tcx> EagerlyNormalizeConsts<'tcx> {
979    fn new(fcx: &FnCtxt<'_, 'tcx>) -> Self {
980        // FIXME(#132279, generic_const_exprs): Using `try_normalize_erasing_regions` here
981        // means we can't handle opaque types in their defining scope.
982        EagerlyNormalizeConsts { tcx: fcx.tcx, typing_env: fcx.typing_env(fcx.param_env) }
983    }
984}
985
986impl<'tcx> TypeFolder<TyCtxt<'tcx>> for EagerlyNormalizeConsts<'tcx> {
987    fn cx(&self) -> TyCtxt<'tcx> {
988        self.tcx
989    }
990
991    fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
992        self.tcx.try_normalize_erasing_regions(self.typing_env, ct).unwrap_or(ct)
993    }
994}
995
996struct HasRecursiveOpaque<'a, 'tcx> {
997    def_id: LocalDefId,
998    seen: FxHashSet<LocalDefId>,
999    opaques: &'a FxIndexMap<LocalDefId, ty::OpaqueHiddenType<'tcx>>,
1000    tcx: TyCtxt<'tcx>,
1001}
1002
1003impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for HasRecursiveOpaque<'_, 'tcx> {
1004    type Result = ControlFlow<()>;
1005
1006    fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
1007        if let ty::Alias(ty::Opaque, alias_ty) = *t.kind()
1008            && let Some(def_id) = alias_ty.def_id.as_local()
1009        {
1010            if self.def_id == def_id {
1011                return ControlFlow::Break(());
1012            }
1013
1014            if self.seen.insert(def_id)
1015                && let Some(hidden_ty) = self.opaques.get(&def_id)
1016            {
1017                ty::EarlyBinder::bind(hidden_ty.ty)
1018                    .instantiate(self.tcx, alias_ty.args)
1019                    .visit_with(self)?;
1020            }
1021        }
1022
1023        t.super_visit_with(self)
1024    }
1025}