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::lang_items::LangItemGroup;
8 use rustc_hir::GeneratorKind;
9 use rustc_middle::mir::{
10 AggregateKind, Constant, Field, Local, LocalInfo, LocalKind, Location, Operand, Place,
11 PlaceRef, ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind,
13 use rustc_middle::ty::print::Print;
14 use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt};
16 hygiene::{DesugaringKind, ForLoopLoc},
20 use rustc_target::abi::VariantIdx;
22 use super::borrow_set::BorrowData;
23 use super::MirBorrowckCtxt;
24 use crate::dataflow::move_paths::{InitLocation, LookupResult};
27 mod outlives_suggestion;
34 mod mutability_errors;
37 crate use mutability_errors::AccessKind;
38 crate use outlives_suggestion::OutlivesSuggestionBuilder;
39 crate use region_errors::{ErrorConstraintInfo, RegionErrorKind, RegionErrors};
40 crate use region_name::{RegionName, RegionNameSource};
41 use rustc_span::symbol::Ident;
43 pub(super) struct IncludingDowncast(pub(super) bool);
45 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
46 /// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure
47 /// is moved after being invoked.
50 /// note: closure cannot be invoked more than once because it moves the variable `dict` out of
52 /// --> $DIR/issue-42065.rs:16:29
54 /// LL | for (key, value) in dict {
57 pub(super) fn add_moved_or_invoked_closure_note(
60 place: PlaceRef<'tcx>,
61 diag: &mut DiagnosticBuilder<'_>,
63 debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);
64 let mut target = place.local_or_deref_local();
65 for stmt in &self.body[location.block].statements[location.statement_index..] {
66 debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target);
67 if let StatementKind::Assign(box (into, Rvalue::Use(from))) = &stmt.kind {
68 debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from);
70 Operand::Copy(ref place) | Operand::Move(ref place)
71 if target == place.local_or_deref_local() =>
73 target = into.local_or_deref_local()
80 // Check if we are attempting to call a closure after it has been invoked.
81 let terminator = self.body[location.block].terminator();
82 debug!("add_moved_or_invoked_closure_note: terminator={:?}", terminator);
83 if let TerminatorKind::Call {
85 Operand::Constant(box Constant {
86 literal: ty::Const { ty: &ty::TyS { kind: ty::FnDef(id, _), .. }, .. },
93 debug!("add_moved_or_invoked_closure_note: id={:?}", id);
94 if self.infcx.tcx.parent(id) == self.infcx.tcx.lang_items().fn_once_trait() {
95 let closure = match args.first() {
96 Some(Operand::Copy(ref place)) | Some(Operand::Move(ref place))
97 if target == place.local_or_deref_local() =>
99 place.local_or_deref_local().unwrap()
104 debug!("add_moved_or_invoked_closure_note: closure={:?}", closure);
105 if let ty::Closure(did, _) = self.body.local_decls[closure].ty.kind {
106 let did = did.expect_local();
107 let hir_id = self.infcx.tcx.hir().as_local_hir_id(did);
109 if let Some((span, name)) =
110 self.infcx.tcx.typeck(did).closure_kind_origins().get(hir_id)
115 "closure cannot be invoked more than once because it moves the \
116 variable `{}` out of its environment",
126 // Check if we are just moving a closure after it has been invoked.
127 if let Some(target) = target {
128 if let ty::Closure(did, _) = self.body.local_decls[target].ty.kind {
129 let did = did.expect_local();
130 let hir_id = self.infcx.tcx.hir().as_local_hir_id(did);
132 if let Some((span, name)) =
133 self.infcx.tcx.typeck(did).closure_kind_origins().get(hir_id)
138 "closure cannot be moved more than once as it is not `Copy` due to \
139 moving the variable `{}` out of its environment",
148 /// End-user visible description of `place` if one can be found.
149 /// If the place is a temporary for instance, `"value"` will be returned.
150 pub(super) fn describe_any_place(&self, place_ref: PlaceRef<'tcx>) -> String {
151 match self.describe_place(place_ref) {
153 // Surround descr with `backticks`.
155 descr.insert_str(0, "`");
159 None => "value".to_string(),
163 /// End-user visible description of `place` if one can be found.
164 /// If the place is a temporary for instance, None will be returned.
165 pub(super) fn describe_place(&self, place_ref: PlaceRef<'tcx>) -> Option<String> {
166 self.describe_place_with_options(place_ref, IncludingDowncast(false))
169 /// End-user visible description of `place` if one can be found. If the
170 /// place is a temporary for instance, None will be returned.
171 /// `IncludingDowncast` parameter makes the function return `Err` if `ProjectionElem` is
172 /// `Downcast` and `IncludingDowncast` is true
173 pub(super) fn describe_place_with_options(
175 place: PlaceRef<'tcx>,
176 including_downcast: IncludingDowncast,
177 ) -> Option<String> {
178 let mut buf = String::new();
179 match self.append_place_to_string(place, &mut buf, false, &including_downcast) {
185 /// Appends end-user visible description of `place` to `buf`.
186 fn append_place_to_string(
188 place: PlaceRef<'tcx>,
191 including_downcast: &IncludingDowncast,
192 ) -> Result<(), ()> {
194 PlaceRef { local, projection: [] } => {
195 self.append_local_to_string(local, buf)?;
197 PlaceRef { local, projection: [ProjectionElem::Deref] }
198 if self.body.local_decls[local].is_ref_for_guard() =>
200 self.append_place_to_string(
201 PlaceRef { local, projection: &[] },
207 PlaceRef { local, projection: [ProjectionElem::Deref] }
208 if self.body.local_decls[local].is_ref_to_static() =>
210 let local_info = &self.body.local_decls[local].local_info;
211 if let Some(box LocalInfo::StaticRef { def_id, .. }) = *local_info {
212 buf.push_str(&self.infcx.tcx.item_name(def_id).as_str());
217 PlaceRef { local, projection: [proj_base @ .., elem] } => {
219 ProjectionElem::Deref => {
220 let upvar_field_projection = self.is_upvar_field_projection(place);
221 if let Some(field) = upvar_field_projection {
222 let var_index = field.index();
223 let name = self.upvars[var_index].name.to_string();
224 if self.upvars[var_index].by_ref {
227 buf.push_str(&format!("*{}", &name));
231 // FIXME turn this recursion into iteration
232 self.append_place_to_string(
233 PlaceRef { local, projection: proj_base },
240 self.append_place_to_string(
241 PlaceRef { local, projection: proj_base },
249 ProjectionElem::Downcast(..) => {
250 self.append_place_to_string(
251 PlaceRef { local, projection: proj_base },
256 if including_downcast.0 {
260 ProjectionElem::Field(field, _ty) => {
263 let upvar_field_projection = self.is_upvar_field_projection(place);
264 if let Some(field) = upvar_field_projection {
265 let var_index = field.index();
266 let name = self.upvars[var_index].name.to_string();
269 let field_name = self
270 .describe_field(PlaceRef { local, projection: proj_base }, *field);
271 self.append_place_to_string(
272 PlaceRef { local, projection: proj_base },
277 buf.push_str(&format!(".{}", field_name));
280 ProjectionElem::Index(index) => {
283 self.append_place_to_string(
284 PlaceRef { local, projection: proj_base },
290 if self.append_local_to_string(*index, buf).is_err() {
295 ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {
297 // Since it isn't possible to borrow an element on a particular index and
298 // then use another while the borrow is held, don't output indices details
299 // to avoid confusing the end-user
300 self.append_place_to_string(
301 PlaceRef { local, projection: proj_base },
306 buf.push_str(&"[..]");
315 /// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have
316 /// a name, or its name was generated by the compiler, then `Err` is returned
317 fn append_local_to_string(&self, local: Local, buf: &mut String) -> Result<(), ()> {
318 let decl = &self.body.local_decls[local];
319 match self.local_names[local] {
320 Some(name) if !decl.from_compiler_desugaring() => {
321 buf.push_str(&name.as_str());
328 /// End-user visible description of the `field`nth field of `base`
329 fn describe_field(&self, place: PlaceRef<'tcx>, field: Field) -> String {
330 // FIXME Place2 Make this work iteratively
332 PlaceRef { local, projection: [] } => {
333 let local = &self.body.local_decls[local];
334 self.describe_field_from_ty(&local.ty, field, None)
336 PlaceRef { local, projection: [proj_base @ .., elem] } => match elem {
337 ProjectionElem::Deref => {
338 self.describe_field(PlaceRef { local, projection: proj_base }, field)
340 ProjectionElem::Downcast(_, variant_index) => {
342 Place::ty_from(place.local, place.projection, self.body, self.infcx.tcx).ty;
343 self.describe_field_from_ty(&base_ty, field, Some(*variant_index))
345 ProjectionElem::Field(_, field_type) => {
346 self.describe_field_from_ty(&field_type, field, None)
348 ProjectionElem::Index(..)
349 | ProjectionElem::ConstantIndex { .. }
350 | ProjectionElem::Subslice { .. } => {
351 self.describe_field(PlaceRef { local, projection: proj_base }, field)
357 /// End-user visible description of the `field_index`nth field of `ty`
358 fn describe_field_from_ty(
362 variant_index: Option<VariantIdx>,
365 // If the type is a box, the field is described from the boxed type
366 self.describe_field_from_ty(&ty.boxed_ty(), field, variant_index)
370 let variant = if let Some(idx) = variant_index {
371 assert!(def.is_enum());
374 def.non_enum_variant()
376 variant.fields[field.index()].ident.to_string()
378 ty::Tuple(_) => field.index().to_string(),
379 ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
380 self.describe_field_from_ty(&ty, field, variant_index)
382 ty::Array(ty, _) | ty::Slice(ty) => {
383 self.describe_field_from_ty(&ty, field, variant_index)
385 ty::Closure(def_id, _) | ty::Generator(def_id, _, _) => {
386 // `tcx.upvars_mentioned(def_id)` returns an `Option`, which is `None` in case
387 // the closure comes from another crate. But in that case we wouldn't
388 // be borrowck'ing it, so we can just unwrap:
389 let (&var_id, _) = self
392 .upvars_mentioned(def_id)
394 .get_index(field.index())
397 self.infcx.tcx.hir().name(var_id).to_string()
400 // Might need a revision when the fields in trait RFC is implemented
401 // (https://github.com/rust-lang/rfcs/pull/1546)
402 bug!("End-user description not implemented for field access on `{:?}`", ty);
408 /// Add a note that a type does not implement `Copy`
409 pub(super) fn note_type_does_not_implement_copy(
411 err: &mut DiagnosticBuilder<'a>,
416 let message = format!(
417 "move occurs because {} has type `{}`, which does not implement the `Copy` trait",
420 if let Some(span) = span {
421 err.span_label(span, message);
427 pub(super) fn borrowed_content_source(
429 deref_base: PlaceRef<'tcx>,
430 ) -> BorrowedContentSource<'tcx> {
431 let tcx = self.infcx.tcx;
433 // Look up the provided place and work out the move path index for it,
434 // we'll use this to check whether it was originally from an overloaded
436 match self.move_data.rev_lookup.find(deref_base) {
437 LookupResult::Exact(mpi) | LookupResult::Parent(Some(mpi)) => {
438 debug!("borrowed_content_source: mpi={:?}", mpi);
440 for i in &self.move_data.init_path_map[mpi] {
441 let init = &self.move_data.inits[*i];
442 debug!("borrowed_content_source: init={:?}", init);
443 // We're only interested in statements that initialized a value, not the
444 // initializations from arguments.
445 let loc = match init.location {
446 InitLocation::Statement(stmt) => stmt,
450 let bbd = &self.body[loc.block];
451 let is_terminator = bbd.statements.len() == loc.statement_index;
453 "borrowed_content_source: loc={:?} is_terminator={:?}",
458 } else if let Some(Terminator {
459 kind: TerminatorKind::Call { ref func, from_hir_call: false, .. },
463 if let Some(source) =
464 BorrowedContentSource::from_call(func.ty(self.body, tcx), tcx)
471 // Base is a `static` so won't be from an overloaded operator
475 // If we didn't find an overloaded deref or index, then assume it's a
476 // built in deref and check the type of the base.
477 let base_ty = Place::ty_from(deref_base.local, deref_base.projection, self.body, tcx).ty;
478 if base_ty.is_unsafe_ptr() {
479 BorrowedContentSource::DerefRawPointer
480 } else if base_ty.is_mutable_ptr() {
481 BorrowedContentSource::DerefMutableRef
483 BorrowedContentSource::DerefSharedRef
488 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
489 /// Return the name of the provided `Ty` (that must be a reference) with a synthesized lifetime
490 /// name where required.
491 pub(super) fn get_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {
492 let mut s = String::new();
493 let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, &mut s, Namespace::TypeNS);
495 // We need to add synthesized lifetimes where appropriate. We do
496 // this by hooking into the pretty printer and telling it to label the
497 // lifetimes without names with the value `'0`.
500 ty::RegionKind::ReLateBound(_, br)
501 | ty::RegionKind::RePlaceholder(ty::PlaceholderRegion { name: br, .. }),
504 ) => printer.region_highlight_mode.highlighting_bound_region(*br, counter),
508 let _ = ty.print(printer);
512 /// Returns the name of the provided `Ty` (that must be a reference)'s region with a
513 /// synthesized lifetime name where required.
514 pub(super) fn get_region_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {
515 let mut s = String::new();
516 let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, &mut s, Namespace::TypeNS);
518 let region = match ty.kind {
519 ty::Ref(region, _, _) => {
521 ty::RegionKind::ReLateBound(_, br)
522 | ty::RegionKind::RePlaceholder(ty::PlaceholderRegion { name: br, .. }) => {
523 printer.region_highlight_mode.highlighting_bound_region(*br, counter)
530 _ => bug!("ty for annotation of borrow region is not a reference"),
533 let _ = region.print(printer);
538 /// The span(s) associated to a use of a place.
539 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
540 pub(super) enum UseSpans {
541 /// The access is caused by capturing a variable for a closure.
543 /// This is true if the captured variable was from a generator.
544 generator_kind: Option<GeneratorKind>,
545 /// The span of the args of the closure, including the `move` keyword if
548 /// The span of the first use of the captured variable inside the closure.
551 /// The access is caused by using a variable as the receiver of a method
552 /// that takes 'self'
554 /// The span of the variable being moved
556 /// The span of the method call on the variable
558 /// The definition span of the method being called
562 /// This access is caused by a `match` or `if let` pattern.
564 /// This access has a single span associated to it: common case.
568 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
569 pub(super) enum FnSelfUseKind {
570 /// A normal method call of the form `receiver.foo(a, b, c)`
571 Normal { self_arg: Ident, implicit_into_iter: bool },
572 /// A call to `FnOnce::call_once`, desugared from `my_closure(a, b, c)`
574 /// A call to an operator trait, desuraged from operator syntax (e.g. `a << b`)
575 Operator { self_arg: Ident },
579 pub(super) fn args_or_use(self) -> Span {
581 UseSpans::ClosureUse { args_span: span, .. }
582 | UseSpans::PatUse(span)
583 | UseSpans::FnSelfUse { var_span: span, .. }
584 | UseSpans::OtherUse(span) => span,
588 pub(super) fn var_or_use(self) -> Span {
590 UseSpans::ClosureUse { var_span: span, .. }
591 | UseSpans::PatUse(span)
592 | UseSpans::FnSelfUse { var_span: span, .. }
593 | UseSpans::OtherUse(span) => span,
597 pub(super) fn generator_kind(self) -> Option<GeneratorKind> {
599 UseSpans::ClosureUse { generator_kind, .. } => generator_kind,
604 // Add a span label to the arguments of the closure, if it exists.
605 pub(super) fn args_span_label(
607 err: &mut DiagnosticBuilder<'_>,
608 message: impl Into<String>,
610 if let UseSpans::ClosureUse { args_span, .. } = self {
611 err.span_label(args_span, message);
615 // Add a span label to the use of the captured variable, if it exists.
616 pub(super) fn var_span_label(
618 err: &mut DiagnosticBuilder<'_>,
619 message: impl Into<String>,
621 if let UseSpans::ClosureUse { var_span, .. } = self {
622 err.span_label(var_span, message);
626 /// Returns `false` if this place is not used in a closure.
627 pub(super) fn for_closure(&self) -> bool {
629 UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_none(),
634 /// Returns `false` if this place is not used in a generator.
635 pub(super) fn for_generator(&self) -> bool {
637 UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_some(),
642 /// Describe the span associated with a use of a place.
643 pub(super) fn describe(&self) -> String {
645 UseSpans::ClosureUse { generator_kind, .. } => {
646 if generator_kind.is_some() {
647 " in generator".to_string()
649 " in closure".to_string()
656 pub(super) fn or_else<F>(self, if_other: F) -> Self
661 closure @ UseSpans::ClosureUse { .. } => closure,
662 UseSpans::PatUse(_) | UseSpans::OtherUse(_) => if_other(),
663 fn_self @ UseSpans::FnSelfUse { .. } => fn_self,
668 pub(super) enum BorrowedContentSource<'tcx> {
672 OverloadedDeref(Ty<'tcx>),
673 OverloadedIndex(Ty<'tcx>),
676 impl BorrowedContentSource<'tcx> {
677 pub(super) fn describe_for_unnamed_place(&self, tcx: TyCtxt<'_>) -> String {
679 BorrowedContentSource::DerefRawPointer => "a raw pointer".to_string(),
680 BorrowedContentSource::DerefSharedRef => "a shared reference".to_string(),
681 BorrowedContentSource::DerefMutableRef => "a mutable reference".to_string(),
682 BorrowedContentSource::OverloadedDeref(ty) => match ty.kind {
683 ty::Adt(def, _) if tcx.is_diagnostic_item(sym::Rc, def.did) => {
684 "an `Rc`".to_string()
686 ty::Adt(def, _) if tcx.is_diagnostic_item(sym::Arc, def.did) => {
687 "an `Arc`".to_string()
689 _ => format!("dereference of `{}`", ty),
691 BorrowedContentSource::OverloadedIndex(ty) => format!("index of `{}`", ty),
695 pub(super) fn describe_for_named_place(&self) -> Option<&'static str> {
697 BorrowedContentSource::DerefRawPointer => Some("raw pointer"),
698 BorrowedContentSource::DerefSharedRef => Some("shared reference"),
699 BorrowedContentSource::DerefMutableRef => Some("mutable reference"),
700 // Overloaded deref and index operators should be evaluated into a
701 // temporary. So we don't need a description here.
702 BorrowedContentSource::OverloadedDeref(_)
703 | BorrowedContentSource::OverloadedIndex(_) => None,
707 pub(super) fn describe_for_immutable_place(&self, tcx: TyCtxt<'_>) -> String {
709 BorrowedContentSource::DerefRawPointer => "a `*const` pointer".to_string(),
710 BorrowedContentSource::DerefSharedRef => "a `&` reference".to_string(),
711 BorrowedContentSource::DerefMutableRef => {
712 bug!("describe_for_immutable_place: DerefMutableRef isn't immutable")
714 BorrowedContentSource::OverloadedDeref(ty) => match ty.kind {
715 ty::Adt(def, _) if tcx.is_diagnostic_item(sym::Rc, def.did) => {
716 "an `Rc`".to_string()
718 ty::Adt(def, _) if tcx.is_diagnostic_item(sym::Arc, def.did) => {
719 "an `Arc`".to_string()
721 _ => format!("a dereference of `{}`", ty),
723 BorrowedContentSource::OverloadedIndex(ty) => format!("an index of `{}`", ty),
727 fn from_call(func: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Self> {
729 ty::FnDef(def_id, substs) => {
730 let trait_id = tcx.trait_of_item(def_id)?;
732 let lang_items = tcx.lang_items();
733 if Some(trait_id) == lang_items.deref_trait()
734 || Some(trait_id) == lang_items.deref_mut_trait()
736 Some(BorrowedContentSource::OverloadedDeref(substs.type_at(0)))
737 } else if Some(trait_id) == lang_items.index_trait()
738 || Some(trait_id) == lang_items.index_mut_trait()
740 Some(BorrowedContentSource::OverloadedIndex(substs.type_at(0)))
750 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
751 /// Finds the spans associated to a move or copy of move_place at location.
752 pub(super) fn move_spans(
754 moved_place: PlaceRef<'tcx>, // Could also be an upvar.
757 use self::UseSpans::*;
759 let stmt = match self.body[location.block].statements.get(location.statement_index) {
761 None => return OtherUse(self.body.source_info(location).span),
764 debug!("move_spans: moved_place={:?} location={:?} stmt={:?}", moved_place, location, stmt);
765 if let StatementKind::Assign(box (_, Rvalue::Aggregate(ref kind, ref places))) = stmt.kind {
767 box AggregateKind::Closure(def_id, _)
768 | box AggregateKind::Generator(def_id, _, _) => {
769 debug!("move_spans: def_id={:?} places={:?}", def_id, places);
770 if let Some((args_span, generator_kind, var_span)) =
771 self.closure_span(*def_id, moved_place, places)
773 return ClosureUse { generator_kind, args_span, var_span };
781 if moved_place.projection.iter().any(|p| matches!(p, ProjectionElem::Downcast(..))) {
782 PatUse(stmt.source_info.span)
784 OtherUse(stmt.source_info.span)
787 // We are trying to find MIR of the form:
789 // _temp = _moved_val;
791 // FnSelfCall(_temp, ...)
794 // where `_moved_val` is the place we generated the move error for,
795 // `_temp` is some other local, and `FnSelfCall` is a function
796 // that has a `self` parameter.
798 let target_temp = match stmt.kind {
799 StatementKind::Assign(box (temp, _)) if temp.as_local().is_some() => {
800 temp.as_local().unwrap()
802 _ => return normal_ret,
805 debug!("move_spans: target_temp = {:?}", target_temp);
807 if let Some(Terminator {
808 kind: TerminatorKind::Call { func, args, fn_span, from_hir_call, .. },
810 }) = &self.body[location.block].terminator
812 let mut method_did = None;
813 if let Operand::Constant(box Constant { literal: ty::Const { ty, .. }, .. }) = func {
814 if let ty::FnDef(def_id, _) = ty.kind {
815 debug!("move_spans: fn = {:?}", def_id);
816 if let Some(ty::AssocItem { fn_has_self_parameter, .. }) =
817 self.infcx.tcx.opt_associated_item(def_id)
819 if *fn_has_self_parameter {
820 method_did = Some(def_id);
826 let tcx = self.infcx.tcx;
827 let method_did = if let Some(did) = method_did { did } else { return normal_ret };
829 if let [Operand::Move(self_place), ..] = **args {
830 if self_place.as_local() == Some(target_temp) {
831 let parent = tcx.parent(method_did);
832 let is_fn_once = parent == tcx.lang_items().fn_once_trait();
833 let is_operator = !from_hir_call
834 && parent.map_or(false, |p| {
835 tcx.lang_items().group(LangItemGroup::Op).contains(&p)
837 let fn_call_span = *fn_span;
839 let self_arg = tcx.fn_arg_names(method_did)[0];
841 let kind = if is_fn_once {
842 FnSelfUseKind::FnOnceCall
843 } else if is_operator {
844 FnSelfUseKind::Operator { self_arg }
847 "move_spans: method_did={:?}, fn_call_span={:?}",
848 method_did, fn_call_span
850 let implicit_into_iter = matches!(
851 fn_call_span.desugaring_kind(),
852 Some(DesugaringKind::ForLoop(ForLoopLoc::IntoIter))
854 FnSelfUseKind::Normal { self_arg, implicit_into_iter }
858 var_span: stmt.source_info.span,
865 .guess_head_span(self.infcx.tcx.def_span(method_did)),
874 /// Finds the span of arguments of a closure (within `maybe_closure_span`)
875 /// and its usage of the local assigned at `location`.
876 /// This is done by searching in statements succeeding `location`
877 /// and originating from `maybe_closure_span`.
878 pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans {
879 use self::UseSpans::*;
880 debug!("borrow_spans: use_span={:?} location={:?}", use_span, location);
882 let target = match self.body[location.block].statements.get(location.statement_index) {
883 Some(&Statement { kind: StatementKind::Assign(box (ref place, _)), .. }) => {
884 if let Some(local) = place.as_local() {
887 return OtherUse(use_span);
890 _ => return OtherUse(use_span),
893 if self.body.local_kind(target) != LocalKind::Temp {
894 // operands are always temporaries.
895 return OtherUse(use_span);
898 for stmt in &self.body[location.block].statements[location.statement_index + 1..] {
899 if let StatementKind::Assign(box (_, Rvalue::Aggregate(ref kind, ref places))) =
902 let (def_id, is_generator) = match kind {
903 box AggregateKind::Closure(def_id, _) => (def_id, false),
904 box AggregateKind::Generator(def_id, _, _) => (def_id, true),
909 "borrow_spans: def_id={:?} is_generator={:?} places={:?}",
910 def_id, is_generator, places
912 if let Some((args_span, generator_kind, var_span)) =
913 self.closure_span(*def_id, Place::from(target).as_ref(), places)
915 return ClosureUse { generator_kind, args_span, var_span };
917 return OtherUse(use_span);
921 if use_span != stmt.source_info.span {
929 /// Finds the span of a captured variable within a closure or generator.
933 target_place: PlaceRef<'tcx>,
934 places: &Vec<Operand<'tcx>>,
935 ) -> Option<(Span, Option<GeneratorKind>, Span)> {
937 "closure_span: def_id={:?} target_place={:?} places={:?}",
938 def_id, target_place, places
940 let hir_id = self.infcx.tcx.hir().as_local_hir_id(def_id.as_local()?);
941 let expr = &self.infcx.tcx.hir().expect_expr(hir_id).kind;
942 debug!("closure_span: hir_id={:?} expr={:?}", hir_id, expr);
943 if let hir::ExprKind::Closure(.., body_id, args_span, _) = expr {
944 for (upvar, place) in self.infcx.tcx.upvars_mentioned(def_id)?.values().zip(places) {
946 Operand::Copy(place) | Operand::Move(place)
947 if target_place == place.as_ref() =>
949 debug!("closure_span: found captured local {:?}", place);
950 let body = self.infcx.tcx.hir().body(*body_id);
951 let generator_kind = body.generator_kind();
952 return Some((*args_span, generator_kind, upvar.span));
961 /// Helper to retrieve span(s) of given borrow from the current MIR
963 pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans {
964 let span = self.body.source_info(borrow.reserve_location).span;
965 self.borrow_spans(span, borrow.reserve_location)