1 //! Borrow checker diagnostics.
3 use rustc_errors::DiagnosticBuilder;
5 use rustc_hir::def::Namespace;
6 use rustc_hir::def_id::DefId;
7 use rustc_hir::GeneratorKind;
8 use rustc_middle::mir::{
9 AggregateKind, Constant, Field, Local, LocalInfo, LocalKind, Location, Operand, Place,
10 PlaceRef, ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind,
12 use rustc_middle::ty::print::Print;
13 use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt};
15 hygiene::{DesugaringKind, ForLoopLoc},
19 use rustc_target::abi::VariantIdx;
21 use super::borrow_set::BorrowData;
22 use super::MirBorrowckCtxt;
23 use crate::dataflow::move_paths::{InitLocation, LookupResult};
26 mod outlives_suggestion;
33 mod mutability_errors;
36 crate use mutability_errors::AccessKind;
37 crate use outlives_suggestion::OutlivesSuggestionBuilder;
38 crate use region_errors::{ErrorConstraintInfo, RegionErrorKind, RegionErrors};
39 crate use region_name::{RegionName, RegionNameSource};
40 use rustc_span::symbol::Ident;
42 pub(super) struct IncludingDowncast(pub(super) bool);
44 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
45 /// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure
46 /// is moved after being invoked.
49 /// note: closure cannot be invoked more than once because it moves the variable `dict` out of
51 /// --> $DIR/issue-42065.rs:16:29
53 /// LL | for (key, value) in dict {
56 pub(super) fn add_moved_or_invoked_closure_note(
59 place: PlaceRef<'tcx>,
60 diag: &mut DiagnosticBuilder<'_>,
62 debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);
63 let mut target = place.local_or_deref_local();
64 for stmt in &self.body[location.block].statements[location.statement_index..] {
65 debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target);
66 if let StatementKind::Assign(box (into, Rvalue::Use(from))) = &stmt.kind {
67 debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from);
69 Operand::Copy(ref place) | Operand::Move(ref place)
70 if target == place.local_or_deref_local() =>
72 target = into.local_or_deref_local()
79 // Check if we are attempting to call a closure after it has been invoked.
80 let terminator = self.body[location.block].terminator();
81 debug!("add_moved_or_invoked_closure_note: terminator={:?}", terminator);
82 if let TerminatorKind::Call {
84 Operand::Constant(box Constant {
85 literal: ty::Const { ty: &ty::TyS { kind: ty::FnDef(id, _), .. }, .. },
92 debug!("add_moved_or_invoked_closure_note: id={:?}", id);
93 if self.infcx.tcx.parent(id) == self.infcx.tcx.lang_items().fn_once_trait() {
94 let closure = match args.first() {
95 Some(Operand::Copy(ref place)) | Some(Operand::Move(ref place))
96 if target == place.local_or_deref_local() =>
98 place.local_or_deref_local().unwrap()
103 debug!("add_moved_or_invoked_closure_note: closure={:?}", closure);
104 if let ty::Closure(did, _) = self.body.local_decls[closure].ty.kind {
105 let did = did.expect_local();
106 let hir_id = self.infcx.tcx.hir().as_local_hir_id(did);
108 if let Some((span, name)) =
109 self.infcx.tcx.typeck_tables_of(did).closure_kind_origins().get(hir_id)
114 "closure cannot be invoked more than once because it moves the \
115 variable `{}` out of its environment",
125 // Check if we are just moving a closure after it has been invoked.
126 if let Some(target) = target {
127 if let ty::Closure(did, _) = self.body.local_decls[target].ty.kind {
128 let did = did.expect_local();
129 let hir_id = self.infcx.tcx.hir().as_local_hir_id(did);
131 if let Some((span, name)) =
132 self.infcx.tcx.typeck_tables_of(did).closure_kind_origins().get(hir_id)
137 "closure cannot be moved more than once as it is not `Copy` due to \
138 moving the variable `{}` out of its environment",
147 /// End-user visible description of `place` if one can be found.
148 /// If the place is a temporary for instance, `"value"` will be returned.
149 pub(super) fn describe_any_place(&self, place_ref: PlaceRef<'tcx>) -> String {
150 match self.describe_place(place_ref) {
152 // Surround descr with `backticks`.
154 descr.insert_str(0, "`");
158 None => "value".to_string(),
162 /// End-user visible description of `place` if one can be found.
163 /// If the place is a temporary for instance, None will be returned.
164 pub(super) fn describe_place(&self, place_ref: PlaceRef<'tcx>) -> Option<String> {
165 self.describe_place_with_options(place_ref, IncludingDowncast(false))
168 /// End-user visible description of `place` if one can be found. If the
169 /// place is a temporary for instance, None will be returned.
170 /// `IncludingDowncast` parameter makes the function return `Err` if `ProjectionElem` is
171 /// `Downcast` and `IncludingDowncast` is true
172 pub(super) fn describe_place_with_options(
174 place: PlaceRef<'tcx>,
175 including_downcast: IncludingDowncast,
176 ) -> Option<String> {
177 let mut buf = String::new();
178 match self.append_place_to_string(place, &mut buf, false, &including_downcast) {
184 /// Appends end-user visible description of `place` to `buf`.
185 fn append_place_to_string(
187 place: PlaceRef<'tcx>,
190 including_downcast: &IncludingDowncast,
191 ) -> Result<(), ()> {
193 PlaceRef { local, projection: [] } => {
194 self.append_local_to_string(local, buf)?;
196 PlaceRef { local, projection: [ProjectionElem::Deref] }
197 if self.body.local_decls[local].is_ref_for_guard() =>
199 self.append_place_to_string(
200 PlaceRef { local, projection: &[] },
206 PlaceRef { local, projection: [ProjectionElem::Deref] }
207 if self.body.local_decls[local].is_ref_to_static() =>
209 let local_info = &self.body.local_decls[local].local_info;
210 if let Some(box LocalInfo::StaticRef { def_id, .. }) = *local_info {
211 buf.push_str(&self.infcx.tcx.item_name(def_id).as_str());
216 PlaceRef { local, projection: [proj_base @ .., elem] } => {
218 ProjectionElem::Deref => {
219 let upvar_field_projection = self.is_upvar_field_projection(place);
220 if let Some(field) = upvar_field_projection {
221 let var_index = field.index();
222 let name = self.upvars[var_index].name.to_string();
223 if self.upvars[var_index].by_ref {
226 buf.push_str(&format!("*{}", &name));
230 // FIXME turn this recursion into iteration
231 self.append_place_to_string(
232 PlaceRef { local, projection: proj_base },
239 self.append_place_to_string(
240 PlaceRef { local, projection: proj_base },
248 ProjectionElem::Downcast(..) => {
249 self.append_place_to_string(
250 PlaceRef { local, projection: proj_base },
255 if including_downcast.0 {
259 ProjectionElem::Field(field, _ty) => {
262 let upvar_field_projection = self.is_upvar_field_projection(place);
263 if let Some(field) = upvar_field_projection {
264 let var_index = field.index();
265 let name = self.upvars[var_index].name.to_string();
268 let field_name = self
269 .describe_field(PlaceRef { local, projection: proj_base }, *field);
270 self.append_place_to_string(
271 PlaceRef { local, projection: proj_base },
276 buf.push_str(&format!(".{}", field_name));
279 ProjectionElem::Index(index) => {
282 self.append_place_to_string(
283 PlaceRef { local, projection: proj_base },
289 if self.append_local_to_string(*index, buf).is_err() {
294 ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {
296 // Since it isn't possible to borrow an element on a particular index and
297 // then use another while the borrow is held, don't output indices details
298 // to avoid confusing the end-user
299 self.append_place_to_string(
300 PlaceRef { local, projection: proj_base },
305 buf.push_str(&"[..]");
314 /// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have
315 /// a name, or its name was generated by the compiler, then `Err` is returned
316 fn append_local_to_string(&self, local: Local, buf: &mut String) -> Result<(), ()> {
317 let decl = &self.body.local_decls[local];
318 match self.local_names[local] {
319 Some(name) if !decl.from_compiler_desugaring() => {
320 buf.push_str(&name.as_str());
327 /// End-user visible description of the `field`nth field of `base`
328 fn describe_field(&self, place: PlaceRef<'tcx>, field: Field) -> String {
329 // FIXME Place2 Make this work iteratively
331 PlaceRef { local, projection: [] } => {
332 let local = &self.body.local_decls[local];
333 self.describe_field_from_ty(&local.ty, field, None)
335 PlaceRef { local, projection: [proj_base @ .., elem] } => match elem {
336 ProjectionElem::Deref => {
337 self.describe_field(PlaceRef { local, projection: proj_base }, field)
339 ProjectionElem::Downcast(_, variant_index) => {
341 Place::ty_from(place.local, place.projection, self.body, self.infcx.tcx).ty;
342 self.describe_field_from_ty(&base_ty, field, Some(*variant_index))
344 ProjectionElem::Field(_, field_type) => {
345 self.describe_field_from_ty(&field_type, field, None)
347 ProjectionElem::Index(..)
348 | ProjectionElem::ConstantIndex { .. }
349 | ProjectionElem::Subslice { .. } => {
350 self.describe_field(PlaceRef { local, projection: proj_base }, field)
356 /// End-user visible description of the `field_index`nth field of `ty`
357 fn describe_field_from_ty(
361 variant_index: Option<VariantIdx>,
364 // If the type is a box, the field is described from the boxed type
365 self.describe_field_from_ty(&ty.boxed_ty(), field, variant_index)
369 let variant = if let Some(idx) = variant_index {
370 assert!(def.is_enum());
373 def.non_enum_variant()
375 variant.fields[field.index()].ident.to_string()
377 ty::Tuple(_) => field.index().to_string(),
378 ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
379 self.describe_field_from_ty(&ty, field, variant_index)
381 ty::Array(ty, _) | ty::Slice(ty) => {
382 self.describe_field_from_ty(&ty, field, variant_index)
384 ty::Closure(def_id, _) | ty::Generator(def_id, _, _) => {
385 // `tcx.upvars_mentioned(def_id)` returns an `Option`, which is `None` in case
386 // the closure comes from another crate. But in that case we wouldn't
387 // be borrowck'ing it, so we can just unwrap:
388 let (&var_id, _) = self
391 .upvars_mentioned(def_id)
393 .get_index(field.index())
396 self.infcx.tcx.hir().name(var_id).to_string()
399 // Might need a revision when the fields in trait RFC is implemented
400 // (https://github.com/rust-lang/rfcs/pull/1546)
401 bug!("End-user description not implemented for field access on `{:?}`", ty);
407 /// Add a note that a type does not implement `Copy`
408 pub(super) fn note_type_does_not_implement_copy(
410 err: &mut DiagnosticBuilder<'a>,
415 let message = format!(
416 "move occurs because {} has type `{}`, which does not implement the `Copy` trait",
419 if let Some(span) = span {
420 err.span_label(span, message);
426 pub(super) fn borrowed_content_source(
428 deref_base: PlaceRef<'tcx>,
429 ) -> BorrowedContentSource<'tcx> {
430 let tcx = self.infcx.tcx;
432 // Look up the provided place and work out the move path index for it,
433 // we'll use this to check whether it was originally from an overloaded
435 match self.move_data.rev_lookup.find(deref_base) {
436 LookupResult::Exact(mpi) | LookupResult::Parent(Some(mpi)) => {
437 debug!("borrowed_content_source: mpi={:?}", mpi);
439 for i in &self.move_data.init_path_map[mpi] {
440 let init = &self.move_data.inits[*i];
441 debug!("borrowed_content_source: init={:?}", init);
442 // We're only interested in statements that initialized a value, not the
443 // initializations from arguments.
444 let loc = match init.location {
445 InitLocation::Statement(stmt) => stmt,
449 let bbd = &self.body[loc.block];
450 let is_terminator = bbd.statements.len() == loc.statement_index;
452 "borrowed_content_source: loc={:?} is_terminator={:?}",
457 } else if let Some(Terminator {
458 kind: TerminatorKind::Call { ref func, from_hir_call: false, .. },
462 if let Some(source) =
463 BorrowedContentSource::from_call(func.ty(self.body, tcx), tcx)
470 // Base is a `static` so won't be from an overloaded operator
474 // If we didn't find an overloaded deref or index, then assume it's a
475 // built in deref and check the type of the base.
476 let base_ty = Place::ty_from(deref_base.local, deref_base.projection, self.body, tcx).ty;
477 if base_ty.is_unsafe_ptr() {
478 BorrowedContentSource::DerefRawPointer
479 } else if base_ty.is_mutable_ptr() {
480 BorrowedContentSource::DerefMutableRef
482 BorrowedContentSource::DerefSharedRef
487 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
488 /// Return the name of the provided `Ty` (that must be a reference) with a synthesized lifetime
489 /// name where required.
490 pub(super) fn get_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {
491 let mut s = String::new();
492 let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, &mut s, Namespace::TypeNS);
494 // We need to add synthesized lifetimes where appropriate. We do
495 // this by hooking into the pretty printer and telling it to label the
496 // lifetimes without names with the value `'0`.
499 ty::RegionKind::ReLateBound(_, br)
500 | ty::RegionKind::RePlaceholder(ty::PlaceholderRegion { name: br, .. }),
503 ) => printer.region_highlight_mode.highlighting_bound_region(*br, counter),
507 let _ = ty.print(printer);
511 /// Returns the name of the provided `Ty` (that must be a reference)'s region with a
512 /// synthesized lifetime name where required.
513 pub(super) fn get_region_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {
514 let mut s = String::new();
515 let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, &mut s, Namespace::TypeNS);
517 let region = match ty.kind {
518 ty::Ref(region, _, _) => {
520 ty::RegionKind::ReLateBound(_, br)
521 | ty::RegionKind::RePlaceholder(ty::PlaceholderRegion { name: br, .. }) => {
522 printer.region_highlight_mode.highlighting_bound_region(*br, counter)
529 _ => bug!("ty for annotation of borrow region is not a reference"),
532 let _ = region.print(printer);
537 /// The span(s) associated to a use of a place.
538 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
539 pub(super) enum UseSpans {
540 /// The access is caused by capturing a variable for a closure.
542 /// This is true if the captured variable was from a generator.
543 generator_kind: Option<GeneratorKind>,
544 /// The span of the args of the closure, including the `move` keyword if
547 /// The span of the first use of the captured variable inside the closure.
550 /// The access is caused by using a variable as the receiver of a method
551 /// that takes 'self'
553 /// The span of the variable being moved
555 /// The span of the method call on the variable
557 /// The definition span of the method being called
561 // This access has a single span associated to it: common case.
565 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
566 pub(super) enum FnSelfUseKind {
567 /// A normal method call of the form `receiver.foo(a, b, c)`
568 Normal { self_arg: Ident, implicit_into_iter: bool },
569 /// A call to `FnOnce::call_once`, desugared from `my_closure(a, b, c)`
571 /// A call to an operator trait, desuraged from operator syntax (e.g. `a << b`)
572 Operator { self_arg: Ident },
576 pub(super) fn args_or_use(self) -> Span {
578 UseSpans::ClosureUse { args_span: span, .. }
579 | UseSpans::FnSelfUse { var_span: span, .. }
580 | UseSpans::OtherUse(span) => span,
584 pub(super) fn var_or_use(self) -> Span {
586 UseSpans::ClosureUse { var_span: span, .. }
587 | UseSpans::FnSelfUse { var_span: span, .. }
588 | UseSpans::OtherUse(span) => span,
592 pub(super) fn generator_kind(self) -> Option<GeneratorKind> {
594 UseSpans::ClosureUse { generator_kind, .. } => generator_kind,
599 // Add a span label to the arguments of the closure, if it exists.
600 pub(super) fn args_span_label(
602 err: &mut DiagnosticBuilder<'_>,
603 message: impl Into<String>,
605 if let UseSpans::ClosureUse { args_span, .. } = self {
606 err.span_label(args_span, message);
610 // Add a span label to the use of the captured variable, if it exists.
611 pub(super) fn var_span_label(
613 err: &mut DiagnosticBuilder<'_>,
614 message: impl Into<String>,
616 if let UseSpans::ClosureUse { var_span, .. } = self {
617 err.span_label(var_span, message);
621 /// Returns `false` if this place is not used in a closure.
622 pub(super) fn for_closure(&self) -> bool {
624 UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_none(),
629 /// Returns `false` if this place is not used in a generator.
630 pub(super) fn for_generator(&self) -> bool {
632 UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_some(),
637 /// Describe the span associated with a use of a place.
638 pub(super) fn describe(&self) -> String {
640 UseSpans::ClosureUse { generator_kind, .. } => {
641 if generator_kind.is_some() {
642 " in generator".to_string()
644 " in closure".to_string()
651 pub(super) fn or_else<F>(self, if_other: F) -> Self
656 closure @ UseSpans::ClosureUse { .. } => closure,
657 fn_self @ UseSpans::FnSelfUse { .. } => fn_self,
658 UseSpans::OtherUse(_) => if_other(),
663 pub(super) enum BorrowedContentSource<'tcx> {
667 OverloadedDeref(Ty<'tcx>),
668 OverloadedIndex(Ty<'tcx>),
671 impl BorrowedContentSource<'tcx> {
672 pub(super) fn describe_for_unnamed_place(&self, tcx: TyCtxt<'_>) -> String {
674 BorrowedContentSource::DerefRawPointer => "a raw pointer".to_string(),
675 BorrowedContentSource::DerefSharedRef => "a shared reference".to_string(),
676 BorrowedContentSource::DerefMutableRef => "a mutable reference".to_string(),
677 BorrowedContentSource::OverloadedDeref(ty) => match ty.kind {
678 ty::Adt(def, _) if tcx.is_diagnostic_item(sym::Rc, def.did) => {
679 "an `Rc`".to_string()
681 ty::Adt(def, _) if tcx.is_diagnostic_item(sym::Arc, def.did) => {
682 "an `Arc`".to_string()
684 _ => format!("dereference of `{}`", ty),
686 BorrowedContentSource::OverloadedIndex(ty) => format!("index of `{}`", ty),
690 pub(super) fn describe_for_named_place(&self) -> Option<&'static str> {
692 BorrowedContentSource::DerefRawPointer => Some("raw pointer"),
693 BorrowedContentSource::DerefSharedRef => Some("shared reference"),
694 BorrowedContentSource::DerefMutableRef => Some("mutable reference"),
695 // Overloaded deref and index operators should be evaluated into a
696 // temporary. So we don't need a description here.
697 BorrowedContentSource::OverloadedDeref(_)
698 | BorrowedContentSource::OverloadedIndex(_) => None,
702 pub(super) fn describe_for_immutable_place(&self, tcx: TyCtxt<'_>) -> String {
704 BorrowedContentSource::DerefRawPointer => "a `*const` pointer".to_string(),
705 BorrowedContentSource::DerefSharedRef => "a `&` reference".to_string(),
706 BorrowedContentSource::DerefMutableRef => {
707 bug!("describe_for_immutable_place: DerefMutableRef isn't immutable")
709 BorrowedContentSource::OverloadedDeref(ty) => match ty.kind {
710 ty::Adt(def, _) if tcx.is_diagnostic_item(sym::Rc, def.did) => {
711 "an `Rc`".to_string()
713 ty::Adt(def, _) if tcx.is_diagnostic_item(sym::Arc, def.did) => {
714 "an `Arc`".to_string()
716 _ => format!("a dereference of `{}`", ty),
718 BorrowedContentSource::OverloadedIndex(ty) => format!("an index of `{}`", ty),
722 fn from_call(func: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Self> {
724 ty::FnDef(def_id, substs) => {
725 let trait_id = tcx.trait_of_item(def_id)?;
727 let lang_items = tcx.lang_items();
728 if Some(trait_id) == lang_items.deref_trait()
729 || Some(trait_id) == lang_items.deref_mut_trait()
731 Some(BorrowedContentSource::OverloadedDeref(substs.type_at(0)))
732 } else if Some(trait_id) == lang_items.index_trait()
733 || Some(trait_id) == lang_items.index_mut_trait()
735 Some(BorrowedContentSource::OverloadedIndex(substs.type_at(0)))
745 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
746 /// Finds the spans associated to a move or copy of move_place at location.
747 pub(super) fn move_spans(
749 moved_place: PlaceRef<'tcx>, // Could also be an upvar.
752 use self::UseSpans::*;
754 let stmt = match self.body[location.block].statements.get(location.statement_index) {
756 None => return OtherUse(self.body.source_info(location).span),
759 debug!("move_spans: moved_place={:?} location={:?} stmt={:?}", moved_place, location, stmt);
760 if let StatementKind::Assign(box (_, Rvalue::Aggregate(ref kind, ref places))) = stmt.kind {
762 box AggregateKind::Closure(def_id, _)
763 | box AggregateKind::Generator(def_id, _, _) => {
764 debug!("move_spans: def_id={:?} places={:?}", def_id, places);
765 if let Some((args_span, generator_kind, var_span)) =
766 self.closure_span(*def_id, moved_place, places)
768 return ClosureUse { generator_kind, args_span, var_span };
775 let normal_ret = OtherUse(stmt.source_info.span);
777 // We are trying to find MIR of the form:
779 // _temp = _moved_val;
781 // FnSelfCall(_temp, ...)
784 // where `_moved_val` is the place we generated the move error for,
785 // `_temp` is some other local, and `FnSelfCall` is a function
786 // that has a `self` parameter.
788 let target_temp = match stmt.kind {
789 StatementKind::Assign(box (temp, _)) if temp.as_local().is_some() => {
790 temp.as_local().unwrap()
792 _ => return normal_ret,
795 debug!("move_spans: target_temp = {:?}", target_temp);
797 if let Some(Terminator { kind: TerminatorKind::Call { func, args, fn_span, .. }, .. }) =
798 &self.body[location.block].terminator
800 let mut method_did = None;
801 if let Operand::Constant(box Constant { literal: ty::Const { ty, .. }, .. }) = func {
802 if let ty::FnDef(def_id, _) = ty.kind {
803 debug!("move_spans: fn = {:?}", def_id);
804 if let Some(ty::AssocItem { fn_has_self_parameter, .. }) =
805 self.infcx.tcx.opt_associated_item(def_id)
807 if *fn_has_self_parameter {
808 method_did = Some(def_id);
814 let tcx = self.infcx.tcx;
815 let method_did = if let Some(did) = method_did { did } else { return normal_ret };
817 if let [Operand::Move(self_place), ..] = **args {
818 if self_place.as_local() == Some(target_temp) {
819 let is_fn_once = tcx.parent(method_did) == tcx.lang_items().fn_once_trait();
820 let fn_call_span = *fn_span;
822 let self_arg = tcx.fn_arg_names(method_did)[0];
824 let kind = if is_fn_once {
825 FnSelfUseKind::FnOnceCall
826 } else if fn_call_span.is_desugaring(DesugaringKind::Operator) {
827 FnSelfUseKind::Operator { self_arg }
830 "move_spans: method_did={:?}, fn_call_span={:?}",
831 method_did, fn_call_span
833 let implicit_into_iter = matches!(
834 fn_call_span.desugaring_kind(),
835 Some(DesugaringKind::ForLoop(ForLoopLoc::IntoIter))
837 FnSelfUseKind::Normal { self_arg, implicit_into_iter }
841 var_span: stmt.source_info.span,
848 .guess_head_span(self.infcx.tcx.def_span(method_did)),
857 /// Finds the span of arguments of a closure (within `maybe_closure_span`)
858 /// and its usage of the local assigned at `location`.
859 /// This is done by searching in statements succeeding `location`
860 /// and originating from `maybe_closure_span`.
861 pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans {
862 use self::UseSpans::*;
863 debug!("borrow_spans: use_span={:?} location={:?}", use_span, location);
865 let target = match self.body[location.block].statements.get(location.statement_index) {
866 Some(&Statement { kind: StatementKind::Assign(box (ref place, _)), .. }) => {
867 if let Some(local) = place.as_local() {
870 return OtherUse(use_span);
873 _ => return OtherUse(use_span),
876 if self.body.local_kind(target) != LocalKind::Temp {
877 // operands are always temporaries.
878 return OtherUse(use_span);
881 for stmt in &self.body[location.block].statements[location.statement_index + 1..] {
882 if let StatementKind::Assign(box (_, Rvalue::Aggregate(ref kind, ref places))) =
885 let (def_id, is_generator) = match kind {
886 box AggregateKind::Closure(def_id, _) => (def_id, false),
887 box AggregateKind::Generator(def_id, _, _) => (def_id, true),
892 "borrow_spans: def_id={:?} is_generator={:?} places={:?}",
893 def_id, is_generator, places
895 if let Some((args_span, generator_kind, var_span)) =
896 self.closure_span(*def_id, Place::from(target).as_ref(), places)
898 return ClosureUse { generator_kind, args_span, var_span };
900 return OtherUse(use_span);
904 if use_span != stmt.source_info.span {
912 /// Finds the span of a captured variable within a closure or generator.
916 target_place: PlaceRef<'tcx>,
917 places: &Vec<Operand<'tcx>>,
918 ) -> Option<(Span, Option<GeneratorKind>, Span)> {
920 "closure_span: def_id={:?} target_place={:?} places={:?}",
921 def_id, target_place, places
923 let hir_id = self.infcx.tcx.hir().as_local_hir_id(def_id.as_local()?);
924 let expr = &self.infcx.tcx.hir().expect_expr(hir_id).kind;
925 debug!("closure_span: hir_id={:?} expr={:?}", hir_id, expr);
926 if let hir::ExprKind::Closure(.., body_id, args_span, _) = expr {
927 for (upvar, place) in self.infcx.tcx.upvars_mentioned(def_id)?.values().zip(places) {
929 Operand::Copy(place) | Operand::Move(place)
930 if target_place == place.as_ref() =>
932 debug!("closure_span: found captured local {:?}", place);
933 let body = self.infcx.tcx.hir().body(*body_id);
934 let generator_kind = body.generator_kind();
935 return Some((*args_span, generator_kind, upvar.span));
944 /// Helper to retrieve span(s) of given borrow from the current MIR
946 pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans {
947 let span = self.body.source_info(borrow.reserve_location).span;
948 self.borrow_spans(span, borrow.reserve_location)