2 use rustc::hir::def::Namespace;
3 use rustc::hir::def_id::DefId;
4 use rustc::hir::GeneratorKind;
6 AggregateKind, Constant, Field, Local, LocalInfo, LocalKind, Location, Operand,
7 Place, PlaceBase, PlaceRef, ProjectionElem, Rvalue, Statement, StatementKind,
8 Static, StaticKind, Terminator, TerminatorKind,
10 use rustc::ty::{self, DefIdTree, Ty, TyCtxt};
11 use rustc::ty::layout::VariantIdx;
12 use rustc::ty::print::Print;
13 use rustc_errors::DiagnosticBuilder;
16 use super::borrow_set::BorrowData;
17 use super::MirBorrowckCtxt;
18 use crate::dataflow::move_paths::{InitLocation, LookupResult};
20 pub(super) struct IncludingDowncast(pub(super) bool);
22 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
23 /// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure
24 /// is moved after being invoked.
27 /// note: closure cannot be invoked more than once because it moves the variable `dict` out of
29 /// --> $DIR/issue-42065.rs:16:29
31 /// LL | for (key, value) in dict {
34 pub(super) fn add_moved_or_invoked_closure_note(
37 place: PlaceRef<'cx, 'tcx>,
38 diag: &mut DiagnosticBuilder<'_>,
40 debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);
41 let mut target = place.local_or_deref_local();
42 for stmt in &self.body[location.block].statements[location.statement_index..] {
43 debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target);
44 if let StatementKind::Assign(box(into, Rvalue::Use(from))) = &stmt.kind {
45 debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from);
47 Operand::Copy(ref place) |
48 Operand::Move(ref place) if target == place.local_or_deref_local() =>
49 target = into.local_or_deref_local(),
55 // Check if we are attempting to call a closure after it has been invoked.
56 let terminator = self.body[location.block].terminator();
57 debug!("add_moved_or_invoked_closure_note: terminator={:?}", terminator);
58 if let TerminatorKind::Call {
59 func: Operand::Constant(box Constant {
61 ty: &ty::TyS { kind: ty::FnDef(id, _), .. },
68 } = &terminator.kind {
69 debug!("add_moved_or_invoked_closure_note: id={:?}", id);
70 if self.infcx.tcx.parent(id) == self.infcx.tcx.lang_items().fn_once_trait() {
71 let closure = match args.first() {
72 Some(Operand::Copy(ref place)) |
73 Some(Operand::Move(ref place)) if target == place.local_or_deref_local() =>
74 place.local_or_deref_local().unwrap(),
78 debug!("add_moved_or_invoked_closure_note: closure={:?}", closure);
79 if let ty::Closure(did, _) = self.body.local_decls[closure].ty.kind {
80 let hir_id = self.infcx.tcx.hir().as_local_hir_id(did).unwrap();
82 if let Some((span, name)) = self.infcx.tcx.typeck_tables_of(did)
83 .closure_kind_origins()
89 "closure cannot be invoked more than once because it moves the \
90 variable `{}` out of its environment",
100 // Check if we are just moving a closure after it has been invoked.
101 if let Some(target) = target {
102 if let ty::Closure(did, _) = self.body.local_decls[target].ty.kind {
103 let hir_id = self.infcx.tcx.hir().as_local_hir_id(did).unwrap();
105 if let Some((span, name)) = self.infcx.tcx.typeck_tables_of(did)
106 .closure_kind_origins()
112 "closure cannot be moved more than once as it is not `Copy` due to \
113 moving the variable `{}` out of its environment",
122 /// End-user visible description of `place` if one can be found. If the
123 /// place is a temporary for instance, None will be returned.
124 pub(super) fn describe_place(&self, place_ref: PlaceRef<'cx, 'tcx>) -> Option<String> {
125 self.describe_place_with_options(place_ref, IncludingDowncast(false))
128 /// End-user visible description of `place` if one can be found. If the
129 /// place is a temporary for instance, None will be returned.
130 /// `IncludingDowncast` parameter makes the function return `Err` if `ProjectionElem` is
131 /// `Downcast` and `IncludingDowncast` is true
132 pub(super) fn describe_place_with_options(
134 place: PlaceRef<'cx, 'tcx>,
135 including_downcast: IncludingDowncast,
136 ) -> Option<String> {
137 let mut buf = String::new();
138 match self.append_place_to_string(place, &mut buf, false, &including_downcast) {
144 /// Appends end-user visible description of `place` to `buf`.
145 fn append_place_to_string(
147 place: PlaceRef<'cx, 'tcx>,
150 including_downcast: &IncludingDowncast,
151 ) -> Result<(), ()> {
154 base: PlaceBase::Local(local),
157 self.append_local_to_string(*local, buf)?;
161 PlaceBase::Static(box Static {
162 kind: StaticKind::Promoted(..),
167 buf.push_str("promoted");
171 PlaceBase::Static(box Static {
172 kind: StaticKind::Static,
178 buf.push_str(&self.infcx.tcx.item_name(*def_id).to_string());
181 base: &PlaceBase::Local(local),
182 projection: [ProjectionElem::Deref]
183 } if self.body.local_decls[local].is_ref_for_guard() => {
184 self.append_place_to_string(
186 base: &PlaceBase::Local(local),
195 base: &PlaceBase::Local(local),
196 projection: [ProjectionElem::Deref]
197 } if self.body.local_decls[local].is_ref_to_static() => {
198 let local_info = &self.body.local_decls[local].local_info;
199 if let LocalInfo::StaticRef { def_id, .. } = *local_info {
200 buf.push_str(&self.infcx.tcx.item_name(def_id).as_str());
207 projection: [proj_base @ .., elem],
210 ProjectionElem::Deref => {
211 let upvar_field_projection =
212 self.is_upvar_field_projection(place);
213 if let Some(field) = upvar_field_projection {
214 let var_index = field.index();
215 let name = self.upvars[var_index].name.to_string();
216 if self.upvars[var_index].by_ref {
219 buf.push_str(&format!("*{}", &name));
223 // FIXME turn this recursion into iteration
224 self.append_place_to_string(
227 projection: proj_base,
234 match (proj_base, base) {
237 self.append_place_to_string(
240 projection: proj_base,
251 ProjectionElem::Downcast(..) => {
252 self.append_place_to_string(
255 projection: proj_base,
261 if including_downcast.0 {
265 ProjectionElem::Field(field, _ty) => {
268 let upvar_field_projection =
269 self.is_upvar_field_projection(place);
270 if let Some(field) = upvar_field_projection {
271 let var_index = field.index();
272 let name = self.upvars[var_index].name.to_string();
275 let field_name = self.describe_field(PlaceRef {
277 projection: proj_base,
279 self.append_place_to_string(
282 projection: proj_base,
288 buf.push_str(&format!(".{}", field_name));
291 ProjectionElem::Index(index) => {
294 self.append_place_to_string(
297 projection: proj_base,
304 if self.append_local_to_string(*index, buf).is_err() {
309 ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {
311 // Since it isn't possible to borrow an element on a particular index and
312 // then use another while the borrow is held, don't output indices details
313 // to avoid confusing the end-user
314 self.append_place_to_string(
317 projection: proj_base,
323 buf.push_str(&"[..]");
332 /// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have
333 /// a name, or its name was generated by the compiler, then `Err` is returned
334 fn append_local_to_string(&self, local: Local, buf: &mut String) -> Result<(), ()> {
335 let decl = &self.body.local_decls[local];
336 match self.local_names[local] {
337 Some(name) if !decl.from_compiler_desugaring() => {
338 buf.push_str(&name.as_str());
345 /// End-user visible description of the `field`nth field of `base`
346 fn describe_field(&self, place: PlaceRef<'cx, 'tcx>, field: Field) -> String {
347 // FIXME Place2 Make this work iteratively
350 base: PlaceBase::Local(local),
353 let local = &self.body.local_decls[*local];
354 self.describe_field_from_ty(&local.ty, field, None)
357 base: PlaceBase::Static(static_),
360 self.describe_field_from_ty(&static_.ty, field, None),
363 projection: [proj_base @ .., elem],
365 ProjectionElem::Deref => {
366 self.describe_field(PlaceRef {
368 projection: proj_base,
371 ProjectionElem::Downcast(_, variant_index) => {
372 let base_ty = Place::ty_from(
377 self.describe_field_from_ty(&base_ty, field, Some(*variant_index))
379 ProjectionElem::Field(_, field_type) => {
380 self.describe_field_from_ty(&field_type, field, None)
382 ProjectionElem::Index(..)
383 | ProjectionElem::ConstantIndex { .. }
384 | ProjectionElem::Subslice { .. } => {
385 self.describe_field(PlaceRef {
387 projection: proj_base,
394 /// End-user visible description of the `field_index`nth field of `ty`
395 fn describe_field_from_ty(
399 variant_index: Option<VariantIdx>
402 // If the type is a box, the field is described from the boxed type
403 self.describe_field_from_ty(&ty.boxed_ty(), field, variant_index)
407 let variant = if let Some(idx) = variant_index {
408 assert!(def.is_enum());
411 def.non_enum_variant()
413 variant.fields[field.index()]
417 ty::Tuple(_) => field.index().to_string(),
418 ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
419 self.describe_field_from_ty(&ty, field, variant_index)
421 ty::Array(ty, _) | ty::Slice(ty) =>
422 self.describe_field_from_ty(&ty, field, variant_index),
423 ty::Closure(def_id, _) | ty::Generator(def_id, _, _) => {
424 // `tcx.upvars(def_id)` returns an `Option`, which is `None` in case
425 // the closure comes from another crate. But in that case we wouldn't
426 // be borrowck'ing it, so we can just unwrap:
427 let (&var_id, _) = self.infcx.tcx.upvars(def_id).unwrap()
428 .get_index(field.index()).unwrap();
430 self.infcx.tcx.hir().name(var_id).to_string()
433 // Might need a revision when the fields in trait RFC is implemented
434 // (https://github.com/rust-lang/rfcs/pull/1546)
436 "End-user description not implemented for field access on `{:?}`",
444 /// Add a note that a type does not implement `Copy`
445 pub(super) fn note_type_does_not_implement_copy(
447 err: &mut DiagnosticBuilder<'a>,
452 let message = format!(
453 "move occurs because {} has type `{}`, which does not implement the `Copy` trait",
457 if let Some(span) = span {
458 err.span_label(span, message);
464 pub(super) fn borrowed_content_source(
466 deref_base: PlaceRef<'cx, 'tcx>,
467 ) -> BorrowedContentSource<'tcx> {
468 let tcx = self.infcx.tcx;
470 // Look up the provided place and work out the move path index for it,
471 // we'll use this to check whether it was originally from an overloaded
473 match self.move_data.rev_lookup.find(deref_base) {
474 LookupResult::Exact(mpi) | LookupResult::Parent(Some(mpi)) => {
475 debug!("borrowed_content_source: mpi={:?}", mpi);
477 for i in &self.move_data.init_path_map[mpi] {
478 let init = &self.move_data.inits[*i];
479 debug!("borrowed_content_source: init={:?}", init);
480 // We're only interested in statements that initialized a value, not the
481 // initializations from arguments.
482 let loc = match init.location {
483 InitLocation::Statement(stmt) => stmt,
487 let bbd = &self.body[loc.block];
488 let is_terminator = bbd.statements.len() == loc.statement_index;
490 "borrowed_content_source: loc={:?} is_terminator={:?}",
496 } else if let Some(Terminator {
497 kind: TerminatorKind::Call {
499 from_hir_call: false,
503 }) = bbd.terminator {
504 if let Some(source) = BorrowedContentSource::from_call(
505 func.ty(*self.body, tcx),
513 // Base is a `static` so won't be from an overloaded operator
517 // If we didn't find an overloaded deref or index, then assume it's a
518 // built in deref and check the type of the base.
519 let base_ty = Place::ty_from(
521 deref_base.projection,
525 if base_ty.is_unsafe_ptr() {
526 BorrowedContentSource::DerefRawPointer
527 } else if base_ty.is_mutable_ptr() {
528 BorrowedContentSource::DerefMutableRef
530 BorrowedContentSource::DerefSharedRef
535 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
536 /// Return the name of the provided `Ty` (that must be a reference) with a synthesized lifetime
537 /// name where required.
538 pub(super) fn get_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {
539 let mut s = String::new();
540 let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, &mut s, Namespace::TypeNS);
542 // We need to add synthesized lifetimes where appropriate. We do
543 // this by hooking into the pretty printer and telling it to label the
544 // lifetimes without names with the value `'0`.
546 ty::Ref(ty::RegionKind::ReLateBound(_, br), _, _)
548 ty::RegionKind::RePlaceholder(ty::PlaceholderRegion { name: br, .. }),
551 ) => printer.region_highlight_mode.highlighting_bound_region(*br, counter),
555 let _ = ty.print(printer);
559 /// Returns the name of the provided `Ty` (that must be a reference)'s region with a
560 /// synthesized lifetime name where required.
561 pub(super) fn get_region_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {
562 let mut s = String::new();
563 let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, &mut s, Namespace::TypeNS);
565 let region = match ty.kind {
566 ty::Ref(region, _, _) => {
568 ty::RegionKind::ReLateBound(_, br)
569 | ty::RegionKind::RePlaceholder(ty::PlaceholderRegion { name: br, .. }) => {
570 printer.region_highlight_mode.highlighting_bound_region(*br, counter)
577 _ => bug!("ty for annotation of borrow region is not a reference"),
580 let _ = region.print(printer);
585 // The span(s) associated to a use of a place.
586 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
587 pub(super) enum UseSpans {
588 // The access is caused by capturing a variable for a closure.
590 // This is true if the captured variable was from a generator.
591 generator_kind: Option<GeneratorKind>,
592 // The span of the args of the closure, including the `move` keyword if
595 // The span of the first use of the captured variable inside the closure.
598 // This access has a single span associated to it: common case.
603 pub(super) fn args_or_use(self) -> Span {
605 UseSpans::ClosureUse {
608 | UseSpans::OtherUse(span) => span,
612 pub(super) fn var_or_use(self) -> Span {
614 UseSpans::ClosureUse { var_span: span, .. } | UseSpans::OtherUse(span) => span,
618 pub(super) fn generator_kind(self) -> Option<GeneratorKind> {
620 UseSpans::ClosureUse { generator_kind, .. } => generator_kind,
625 // Add a span label to the arguments of the closure, if it exists.
626 pub(super) fn args_span_label(
628 err: &mut DiagnosticBuilder<'_>,
629 message: impl Into<String>,
631 if let UseSpans::ClosureUse { args_span, .. } = self {
632 err.span_label(args_span, message);
636 // Add a span label to the use of the captured variable, if it exists.
637 pub(super) fn var_span_label(
639 err: &mut DiagnosticBuilder<'_>,
640 message: impl Into<String>,
642 if let UseSpans::ClosureUse { var_span, .. } = self {
643 err.span_label(var_span, message);
647 /// Returns `false` if this place is not used in a closure.
648 pub(super) fn for_closure(&self) -> bool {
650 UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_none(),
655 /// Returns `false` if this place is not used in a generator.
656 pub(super) fn for_generator(&self) -> bool {
658 UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_some(),
663 /// Describe the span associated with a use of a place.
664 pub(super) fn describe(&self) -> String {
666 UseSpans::ClosureUse { generator_kind, .. } => if generator_kind.is_some() {
667 " in generator".to_string()
669 " in closure".to_string()
675 pub(super) fn or_else<F>(self, if_other: F) -> Self
680 closure @ UseSpans::ClosureUse { .. } => closure,
681 UseSpans::OtherUse(_) => if_other(),
686 pub(super) enum BorrowedContentSource<'tcx> {
690 OverloadedDeref(Ty<'tcx>),
691 OverloadedIndex(Ty<'tcx>),
694 impl BorrowedContentSource<'tcx> {
695 pub(super) fn describe_for_unnamed_place(&self) -> String {
697 BorrowedContentSource::DerefRawPointer => format!("a raw pointer"),
698 BorrowedContentSource::DerefSharedRef => format!("a shared reference"),
699 BorrowedContentSource::DerefMutableRef => {
700 format!("a mutable reference")
702 BorrowedContentSource::OverloadedDeref(ty) => {
705 } else if ty.is_arc() {
708 format!("dereference of `{}`", ty)
711 BorrowedContentSource::OverloadedIndex(ty) => format!("index of `{}`", ty),
715 pub(super) fn describe_for_named_place(&self) -> Option<&'static str> {
717 BorrowedContentSource::DerefRawPointer => Some("raw pointer"),
718 BorrowedContentSource::DerefSharedRef => Some("shared reference"),
719 BorrowedContentSource::DerefMutableRef => Some("mutable reference"),
720 // Overloaded deref and index operators should be evaluated into a
721 // temporary. So we don't need a description here.
722 BorrowedContentSource::OverloadedDeref(_)
723 | BorrowedContentSource::OverloadedIndex(_) => None
727 pub(super) fn describe_for_immutable_place(&self) -> String {
729 BorrowedContentSource::DerefRawPointer => format!("a `*const` pointer"),
730 BorrowedContentSource::DerefSharedRef => format!("a `&` reference"),
731 BorrowedContentSource::DerefMutableRef => {
732 bug!("describe_for_immutable_place: DerefMutableRef isn't immutable")
734 BorrowedContentSource::OverloadedDeref(ty) => {
737 } else if ty.is_arc() {
740 format!("a dereference of `{}`", ty)
743 BorrowedContentSource::OverloadedIndex(ty) => format!("an index of `{}`", ty),
747 fn from_call(func: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Self> {
749 ty::FnDef(def_id, substs) => {
750 let trait_id = tcx.trait_of_item(def_id)?;
752 let lang_items = tcx.lang_items();
753 if Some(trait_id) == lang_items.deref_trait()
754 || Some(trait_id) == lang_items.deref_mut_trait()
756 Some(BorrowedContentSource::OverloadedDeref(substs.type_at(0)))
757 } else if Some(trait_id) == lang_items.index_trait()
758 || Some(trait_id) == lang_items.index_mut_trait()
760 Some(BorrowedContentSource::OverloadedIndex(substs.type_at(0)))
770 impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
771 /// Finds the spans associated to a move or copy of move_place at location.
772 pub(super) fn move_spans(
774 moved_place: PlaceRef<'cx, 'tcx>, // Could also be an upvar.
777 use self::UseSpans::*;
779 let stmt = match self.body[location.block].statements.get(location.statement_index) {
781 None => return OtherUse(self.body.source_info(location).span),
784 debug!("move_spans: moved_place={:?} location={:?} stmt={:?}", moved_place, location, stmt);
785 if let StatementKind::Assign(
786 box(_, Rvalue::Aggregate(ref kind, ref places))
788 let def_id = match kind {
789 box AggregateKind::Closure(def_id, _)
790 | box AggregateKind::Generator(def_id, _, _) => def_id,
791 _ => return OtherUse(stmt.source_info.span),
795 "move_spans: def_id={:?} places={:?}",
798 if let Some((args_span, generator_kind, var_span))
799 = self.closure_span(*def_id, moved_place, places) {
808 OtherUse(stmt.source_info.span)
811 /// Finds the span of arguments of a closure (within `maybe_closure_span`)
812 /// and its usage of the local assigned at `location`.
813 /// This is done by searching in statements succeeding `location`
814 /// and originating from `maybe_closure_span`.
815 pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans {
816 use self::UseSpans::*;
817 debug!("borrow_spans: use_span={:?} location={:?}", use_span, location);
819 let target = match self.body[location.block]
821 .get(location.statement_index)
824 kind: StatementKind::Assign(box(ref place, _)),
827 if let Some(local) = place.as_local() {
830 return OtherUse(use_span);
833 _ => return OtherUse(use_span),
836 if self.body.local_kind(target) != LocalKind::Temp {
837 // operands are always temporaries.
838 return OtherUse(use_span);
841 for stmt in &self.body[location.block].statements[location.statement_index + 1..] {
842 if let StatementKind::Assign(
843 box(_, Rvalue::Aggregate(ref kind, ref places))
845 let (def_id, is_generator) = match kind {
846 box AggregateKind::Closure(def_id, _) => (def_id, false),
847 box AggregateKind::Generator(def_id, _, _) => (def_id, true),
852 "borrow_spans: def_id={:?} is_generator={:?} places={:?}",
853 def_id, is_generator, places
855 if let Some((args_span, generator_kind, var_span)) = self.closure_span(
856 *def_id, Place::from(target).as_ref(), places
864 return OtherUse(use_span);
868 if use_span != stmt.source_info.span {
876 /// Finds the span of a captured variable within a closure or generator.
880 target_place: PlaceRef<'cx, 'tcx>,
881 places: &Vec<Operand<'tcx>>,
882 ) -> Option<(Span, Option<GeneratorKind>, Span)> {
884 "closure_span: def_id={:?} target_place={:?} places={:?}",
885 def_id, target_place, places
887 let hir_id = self.infcx.tcx.hir().as_local_hir_id(def_id)?;
888 let expr = &self.infcx.tcx.hir().expect_expr(hir_id).kind;
889 debug!("closure_span: hir_id={:?} expr={:?}", hir_id, expr);
890 if let hir::ExprKind::Closure(
891 .., body_id, args_span, _
893 for (upvar, place) in self.infcx.tcx.upvars(def_id)?.values().zip(places) {
895 Operand::Copy(place) |
896 Operand::Move(place) if target_place == place.as_ref() => {
897 debug!("closure_span: found captured local {:?}", place);
898 let body = self.infcx.tcx.hir().body(*body_id);
899 let generator_kind = body.generator_kind();
900 return Some((*args_span, generator_kind, upvar.span));
910 /// Helper to retrieve span(s) of given borrow from the current MIR
912 pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans {
913 let span = self.body.source_info(borrow.reserve_location).span;
914 self.borrow_spans(span, borrow.reserve_location)