| //! Borrow checker diagnostics. |
| |
| use crate::session_diagnostics::{ |
| CaptureArgLabel, CaptureReasonLabel, CaptureReasonNote, CaptureReasonSuggest, CaptureVarCause, |
| CaptureVarKind, CaptureVarPathUseCause, OnClosureNote, |
| }; |
| use itertools::Itertools; |
| use rustc_errors::{Applicability, Diagnostic}; |
| use rustc_hir as hir; |
| use rustc_hir::def::{CtorKind, Namespace}; |
| use rustc_hir::GeneratorKind; |
| use rustc_index::IndexSlice; |
| use rustc_infer::infer::LateBoundRegionConversionTime; |
| use rustc_middle::mir::tcx::PlaceTy; |
| use rustc_middle::mir::{ |
| AggregateKind, Constant, FakeReadCause, Local, LocalInfo, LocalKind, Location, Operand, Place, |
| PlaceRef, ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind, |
| }; |
| use rustc_middle::ty::print::Print; |
| use rustc_middle::ty::{self, Instance, Ty, TyCtxt}; |
| use rustc_middle::util::{call_kind, CallDesugaringKind}; |
| use rustc_mir_dataflow::move_paths::{InitLocation, LookupResult}; |
| use rustc_span::def_id::LocalDefId; |
| use rustc_span::{symbol::sym, Span, Symbol, DUMMY_SP}; |
| use rustc_target::abi::{FieldIdx, VariantIdx}; |
| use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt; |
| use rustc_trait_selection::traits::{ |
| type_known_to_meet_bound_modulo_regions, Obligation, ObligationCause, |
| }; |
| |
| use super::borrow_set::BorrowData; |
| use super::MirBorrowckCtxt; |
| |
| mod find_all_local_uses; |
| mod find_use; |
| mod outlives_suggestion; |
| mod region_name; |
| mod var_name; |
| |
| mod bound_region_errors; |
| mod conflict_errors; |
| mod explain_borrow; |
| mod move_errors; |
| mod mutability_errors; |
| mod region_errors; |
| |
| pub(crate) use bound_region_errors::{ToUniverseInfo, UniverseInfo}; |
| pub(crate) use mutability_errors::AccessKind; |
| pub(crate) use outlives_suggestion::OutlivesSuggestionBuilder; |
| pub(crate) use region_errors::{ErrorConstraintInfo, RegionErrorKind, RegionErrors}; |
| pub(crate) use region_name::{RegionName, RegionNameSource}; |
| pub(crate) use rustc_middle::util::CallKind; |
| |
| pub(super) struct DescribePlaceOpt { |
| pub including_downcast: bool, |
| |
| /// Enable/Disable tuple fields. |
| /// For example `x` tuple. if it's `true` `x.0`. Otherwise `x` |
| pub including_tuple_field: bool, |
| } |
| |
| pub(super) struct IncludingTupleField(pub(super) bool); |
| |
| impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { |
| /// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure |
| /// is moved after being invoked. |
| /// |
| /// ```text |
| /// note: closure cannot be invoked more than once because it moves the variable `dict` out of |
| /// its environment |
| /// --> $DIR/issue-42065.rs:16:29 |
| /// | |
| /// LL | for (key, value) in dict { |
| /// | ^^^^ |
| /// ``` |
| pub(super) fn add_moved_or_invoked_closure_note( |
| &self, |
| location: Location, |
| place: PlaceRef<'tcx>, |
| diag: &mut Diagnostic, |
| ) -> bool { |
| debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place); |
| let mut target = place.local_or_deref_local(); |
| for stmt in &self.body[location.block].statements[location.statement_index..] { |
| debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target); |
| if let StatementKind::Assign(box (into, Rvalue::Use(from))) = &stmt.kind { |
| debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from); |
| match from { |
| Operand::Copy(place) | Operand::Move(place) |
| if target == place.local_or_deref_local() => |
| { |
| target = into.local_or_deref_local() |
| } |
| _ => {} |
| } |
| } |
| } |
| |
| // Check if we are attempting to call a closure after it has been invoked. |
| let terminator = self.body[location.block].terminator(); |
| debug!("add_moved_or_invoked_closure_note: terminator={:?}", terminator); |
| if let TerminatorKind::Call { |
| func: Operand::Constant(box Constant { literal, .. }), |
| args, |
| .. |
| } = &terminator.kind |
| { |
| if let ty::FnDef(id, _) = *literal.ty().kind() { |
| debug!("add_moved_or_invoked_closure_note: id={:?}", id); |
| if Some(self.infcx.tcx.parent(id)) == self.infcx.tcx.lang_items().fn_once_trait() { |
| let closure = match args.first() { |
| Some(Operand::Copy(place) | Operand::Move(place)) |
| if target == place.local_or_deref_local() => |
| { |
| place.local_or_deref_local().unwrap() |
| } |
| _ => return false, |
| }; |
| |
| debug!("add_moved_or_invoked_closure_note: closure={:?}", closure); |
| if let ty::Closure(did, _) = self.body.local_decls[closure].ty.kind() { |
| let did = did.expect_local(); |
| if let Some((span, hir_place)) = self.infcx.tcx.closure_kind_origin(did) { |
| diag.eager_subdiagnostic( |
| &self.infcx.tcx.sess.parse_sess.span_diagnostic, |
| OnClosureNote::InvokedTwice { |
| place_name: &ty::place_to_string_for_capture( |
| self.infcx.tcx, |
| hir_place, |
| ), |
| span: *span, |
| }, |
| ); |
| return true; |
| } |
| } |
| } |
| } |
| } |
| |
| // Check if we are just moving a closure after it has been invoked. |
| if let Some(target) = target { |
| if let ty::Closure(did, _) = self.body.local_decls[target].ty.kind() { |
| let did = did.expect_local(); |
| if let Some((span, hir_place)) = self.infcx.tcx.closure_kind_origin(did) { |
| diag.eager_subdiagnostic( |
| &self.infcx.tcx.sess.parse_sess.span_diagnostic, |
| OnClosureNote::MovedTwice { |
| place_name: &ty::place_to_string_for_capture(self.infcx.tcx, hir_place), |
| span: *span, |
| }, |
| ); |
| return true; |
| } |
| } |
| } |
| false |
| } |
| |
| /// End-user visible description of `place` if one can be found. |
| /// If the place is a temporary for instance, `"value"` will be returned. |
| pub(super) fn describe_any_place(&self, place_ref: PlaceRef<'tcx>) -> String { |
| match self.describe_place(place_ref) { |
| Some(mut descr) => { |
| // Surround descr with `backticks`. |
| descr.reserve(2); |
| descr.insert(0, '`'); |
| descr.push('`'); |
| descr |
| } |
| None => "value".to_string(), |
| } |
| } |
| |
| /// End-user visible description of `place` if one can be found. |
| /// If the place is a temporary for instance, `None` will be returned. |
| pub(super) fn describe_place(&self, place_ref: PlaceRef<'tcx>) -> Option<String> { |
| self.describe_place_with_options( |
| place_ref, |
| DescribePlaceOpt { including_downcast: false, including_tuple_field: true }, |
| ) |
| } |
| |
| /// End-user visible description of `place` if one can be found. If the place is a temporary |
| /// for instance, `None` will be returned. |
| /// `IncludingDowncast` parameter makes the function return `None` if `ProjectionElem` is |
| /// `Downcast` and `IncludingDowncast` is true |
| pub(super) fn describe_place_with_options( |
| &self, |
| place: PlaceRef<'tcx>, |
| opt: DescribePlaceOpt, |
| ) -> Option<String> { |
| let local = place.local; |
| let mut autoderef_index = None; |
| let mut buf = String::new(); |
| let mut ok = self.append_local_to_string(local, &mut buf); |
| |
| for (index, elem) in place.projection.into_iter().enumerate() { |
| match elem { |
| ProjectionElem::Deref => { |
| if index == 0 { |
| if self.body.local_decls[local].is_ref_for_guard() { |
| continue; |
| } |
| if let LocalInfo::StaticRef { def_id, .. } = |
| *self.body.local_decls[local].local_info() |
| { |
| buf.push_str(self.infcx.tcx.item_name(def_id).as_str()); |
| ok = Ok(()); |
| continue; |
| } |
| } |
| if let Some(field) = self.is_upvar_field_projection(PlaceRef { |
| local, |
| projection: place.projection.split_at(index + 1).0, |
| }) { |
| let var_index = field.index(); |
| buf = self.upvars[var_index].place.to_string(self.infcx.tcx); |
| ok = Ok(()); |
| if !self.upvars[var_index].by_ref { |
| buf.insert(0, '*'); |
| } |
| } else { |
| if autoderef_index.is_none() { |
| autoderef_index = |
| match place.projection.into_iter().rev().find_position(|elem| { |
| !matches!( |
| elem, |
| ProjectionElem::Deref | ProjectionElem::Downcast(..) |
| ) |
| }) { |
| Some((index, _)) => Some(place.projection.len() - index), |
| None => Some(0), |
| }; |
| } |
| if index >= autoderef_index.unwrap() { |
| buf.insert(0, '*'); |
| } |
| } |
| } |
| ProjectionElem::Downcast(..) if opt.including_downcast => return None, |
| ProjectionElem::Downcast(..) => (), |
| ProjectionElem::OpaqueCast(..) => (), |
| ProjectionElem::Field(field, _ty) => { |
| // FIXME(project-rfc_2229#36): print capture precisely here. |
| if let Some(field) = self.is_upvar_field_projection(PlaceRef { |
| local, |
| projection: place.projection.split_at(index + 1).0, |
| }) { |
| buf = self.upvars[field.index()].place.to_string(self.infcx.tcx); |
| ok = Ok(()); |
| } else { |
| let field_name = self.describe_field( |
| PlaceRef { local, projection: place.projection.split_at(index).0 }, |
| *field, |
| IncludingTupleField(opt.including_tuple_field), |
| ); |
| if let Some(field_name_str) = field_name { |
| buf.push('.'); |
| buf.push_str(&field_name_str); |
| } |
| } |
| } |
| ProjectionElem::Index(index) => { |
| buf.push('['); |
| if self.append_local_to_string(*index, &mut buf).is_err() { |
| buf.push('_'); |
| } |
| buf.push(']'); |
| } |
| ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => { |
| // Since it isn't possible to borrow an element on a particular index and |
| // then use another while the borrow is held, don't output indices details |
| // to avoid confusing the end-user |
| buf.push_str("[..]"); |
| } |
| } |
| } |
| ok.ok().map(|_| buf) |
| } |
| |
| fn describe_name(&self, place: PlaceRef<'tcx>) -> Option<Symbol> { |
| for elem in place.projection.into_iter() { |
| match elem { |
| ProjectionElem::Downcast(Some(name), _) => { |
| return Some(*name); |
| } |
| _ => {} |
| } |
| } |
| None |
| } |
| |
| /// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have |
| /// a name, or its name was generated by the compiler, then `Err` is returned |
| fn append_local_to_string(&self, local: Local, buf: &mut String) -> Result<(), ()> { |
| let decl = &self.body.local_decls[local]; |
| match self.local_names[local] { |
| Some(name) if !decl.from_compiler_desugaring() => { |
| buf.push_str(name.as_str()); |
| Ok(()) |
| } |
| _ => Err(()), |
| } |
| } |
| |
| /// End-user visible description of the `field`nth field of `base` |
| fn describe_field( |
| &self, |
| place: PlaceRef<'tcx>, |
| field: FieldIdx, |
| including_tuple_field: IncludingTupleField, |
| ) -> Option<String> { |
| let place_ty = match place { |
| PlaceRef { local, projection: [] } => PlaceTy::from_ty(self.body.local_decls[local].ty), |
| PlaceRef { local, projection: [proj_base @ .., elem] } => match elem { |
| ProjectionElem::Deref |
| | ProjectionElem::Index(..) |
| | ProjectionElem::ConstantIndex { .. } |
| | ProjectionElem::Subslice { .. } => { |
| PlaceRef { local, projection: proj_base }.ty(self.body, self.infcx.tcx) |
| } |
| ProjectionElem::Downcast(..) => place.ty(self.body, self.infcx.tcx), |
| ProjectionElem::OpaqueCast(ty) => PlaceTy::from_ty(*ty), |
| ProjectionElem::Field(_, field_type) => PlaceTy::from_ty(*field_type), |
| }, |
| }; |
| self.describe_field_from_ty( |
| place_ty.ty, |
| field, |
| place_ty.variant_index, |
| including_tuple_field, |
| ) |
| } |
| |
| /// End-user visible description of the `field_index`nth field of `ty` |
| fn describe_field_from_ty( |
| &self, |
| ty: Ty<'_>, |
| field: FieldIdx, |
| variant_index: Option<VariantIdx>, |
| including_tuple_field: IncludingTupleField, |
| ) -> Option<String> { |
| if ty.is_box() { |
| // If the type is a box, the field is described from the boxed type |
| self.describe_field_from_ty(ty.boxed_ty(), field, variant_index, including_tuple_field) |
| } else { |
| match *ty.kind() { |
| ty::Adt(def, _) => { |
| let variant = if let Some(idx) = variant_index { |
| assert!(def.is_enum()); |
| &def.variant(idx) |
| } else { |
| def.non_enum_variant() |
| }; |
| if !including_tuple_field.0 && variant.ctor_kind() == Some(CtorKind::Fn) { |
| return None; |
| } |
| Some(variant.fields[field].name.to_string()) |
| } |
| ty::Tuple(_) => Some(field.index().to_string()), |
| ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => { |
| self.describe_field_from_ty(ty, field, variant_index, including_tuple_field) |
| } |
| ty::Array(ty, _) | ty::Slice(ty) => { |
| self.describe_field_from_ty(ty, field, variant_index, including_tuple_field) |
| } |
| ty::Closure(def_id, _) | ty::Generator(def_id, _, _) => { |
| // We won't be borrowck'ing here if the closure came from another crate, |
| // so it's safe to call `expect_local`. |
| // |
| // We know the field exists so it's safe to call operator[] and `unwrap` here. |
| let def_id = def_id.expect_local(); |
| let var_id = |
| self.infcx.tcx.closure_captures(def_id)[field.index()].get_root_variable(); |
| |
| Some(self.infcx.tcx.hir().name(var_id).to_string()) |
| } |
| _ => { |
| // Might need a revision when the fields in trait RFC is implemented |
| // (https://github.com/rust-lang/rfcs/pull/1546) |
| bug!("End-user description not implemented for field access on `{:?}`", ty); |
| } |
| } |
| } |
| } |
| |
| pub(super) fn borrowed_content_source( |
| &self, |
| deref_base: PlaceRef<'tcx>, |
| ) -> BorrowedContentSource<'tcx> { |
| let tcx = self.infcx.tcx; |
| |
| // Look up the provided place and work out the move path index for it, |
| // we'll use this to check whether it was originally from an overloaded |
| // operator. |
| match self.move_data.rev_lookup.find(deref_base) { |
| LookupResult::Exact(mpi) | LookupResult::Parent(Some(mpi)) => { |
| debug!("borrowed_content_source: mpi={:?}", mpi); |
| |
| for i in &self.move_data.init_path_map[mpi] { |
| let init = &self.move_data.inits[*i]; |
| debug!("borrowed_content_source: init={:?}", init); |
| // We're only interested in statements that initialized a value, not the |
| // initializations from arguments. |
| let InitLocation::Statement(loc) = init.location else { continue }; |
| |
| let bbd = &self.body[loc.block]; |
| let is_terminator = bbd.statements.len() == loc.statement_index; |
| debug!( |
| "borrowed_content_source: loc={:?} is_terminator={:?}", |
| loc, is_terminator, |
| ); |
| if !is_terminator { |
| continue; |
| } else if let Some(Terminator { |
| kind: TerminatorKind::Call { func, from_hir_call: false, .. }, |
| .. |
| }) = &bbd.terminator |
| { |
| if let Some(source) = |
| BorrowedContentSource::from_call(func.ty(self.body, tcx), tcx) |
| { |
| return source; |
| } |
| } |
| } |
| } |
| // Base is a `static` so won't be from an overloaded operator |
| _ => (), |
| }; |
| |
| // If we didn't find an overloaded deref or index, then assume it's a |
| // built in deref and check the type of the base. |
| let base_ty = deref_base.ty(self.body, tcx).ty; |
| if base_ty.is_unsafe_ptr() { |
| BorrowedContentSource::DerefRawPointer |
| } else if base_ty.is_mutable_ptr() { |
| BorrowedContentSource::DerefMutableRef |
| } else { |
| BorrowedContentSource::DerefSharedRef |
| } |
| } |
| |
| /// Return the name of the provided `Ty` (that must be a reference) with a synthesized lifetime |
| /// name where required. |
| pub(super) fn get_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String { |
| let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, Namespace::TypeNS); |
| |
| // We need to add synthesized lifetimes where appropriate. We do |
| // this by hooking into the pretty printer and telling it to label the |
| // lifetimes without names with the value `'0`. |
| if let ty::Ref(region, ..) = ty.kind() { |
| match **region { |
| ty::ReLateBound(_, ty::BoundRegion { kind: br, .. }) |
| | ty::RePlaceholder(ty::PlaceholderRegion { |
| bound: ty::BoundRegion { kind: br, .. }, |
| .. |
| }) => printer.region_highlight_mode.highlighting_bound_region(br, counter), |
| _ => {} |
| } |
| } |
| |
| ty.print(printer).unwrap().into_buffer() |
| } |
| |
| /// Returns the name of the provided `Ty` (that must be a reference)'s region with a |
| /// synthesized lifetime name where required. |
| pub(super) fn get_region_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String { |
| let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, Namespace::TypeNS); |
| |
| let region = if let ty::Ref(region, ..) = ty.kind() { |
| match **region { |
| ty::ReLateBound(_, ty::BoundRegion { kind: br, .. }) |
| | ty::RePlaceholder(ty::PlaceholderRegion { |
| bound: ty::BoundRegion { kind: br, .. }, |
| .. |
| }) => printer.region_highlight_mode.highlighting_bound_region(br, counter), |
| _ => {} |
| } |
| region |
| } else { |
| bug!("ty for annotation of borrow region is not a reference"); |
| }; |
| |
| region.print(printer).unwrap().into_buffer() |
| } |
| } |
| |
| /// The span(s) associated to a use of a place. |
| #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
| pub(super) enum UseSpans<'tcx> { |
| /// The access is caused by capturing a variable for a closure. |
| ClosureUse { |
| /// This is true if the captured variable was from a generator. |
| generator_kind: Option<GeneratorKind>, |
| /// The span of the args of the closure, including the `move` keyword if |
| /// it's present. |
| args_span: Span, |
| /// The span of the use resulting in capture kind |
| /// Check `ty::CaptureInfo` for more details |
| capture_kind_span: Span, |
| /// The span of the use resulting in the captured path |
| /// Check `ty::CaptureInfo` for more details |
| path_span: Span, |
| }, |
| /// The access is caused by using a variable as the receiver of a method |
| /// that takes 'self' |
| FnSelfUse { |
| /// The span of the variable being moved |
| var_span: Span, |
| /// The span of the method call on the variable |
| fn_call_span: Span, |
| /// The definition span of the method being called |
| fn_span: Span, |
| kind: CallKind<'tcx>, |
| }, |
| /// This access is caused by a `match` or `if let` pattern. |
| PatUse(Span), |
| /// This access has a single span associated to it: common case. |
| OtherUse(Span), |
| } |
| |
| impl UseSpans<'_> { |
| pub(super) fn args_or_use(self) -> Span { |
| match self { |
| UseSpans::ClosureUse { args_span: span, .. } |
| | UseSpans::PatUse(span) |
| | UseSpans::OtherUse(span) => span, |
| UseSpans::FnSelfUse { fn_call_span, kind: CallKind::DerefCoercion { .. }, .. } => { |
| fn_call_span |
| } |
| UseSpans::FnSelfUse { var_span, .. } => var_span, |
| } |
| } |
| |
| /// Returns the span of `self`, in the case of a `ClosureUse` returns the `path_span` |
| pub(super) fn var_or_use_path_span(self) -> Span { |
| match self { |
| UseSpans::ClosureUse { path_span: span, .. } |
| | UseSpans::PatUse(span) |
| | UseSpans::OtherUse(span) => span, |
| UseSpans::FnSelfUse { fn_call_span, kind: CallKind::DerefCoercion { .. }, .. } => { |
| fn_call_span |
| } |
| UseSpans::FnSelfUse { var_span, .. } => var_span, |
| } |
| } |
| |
| /// Returns the span of `self`, in the case of a `ClosureUse` returns the `capture_kind_span` |
| pub(super) fn var_or_use(self) -> Span { |
| match self { |
| UseSpans::ClosureUse { capture_kind_span: span, .. } |
| | UseSpans::PatUse(span) |
| | UseSpans::OtherUse(span) => span, |
| UseSpans::FnSelfUse { fn_call_span, kind: CallKind::DerefCoercion { .. }, .. } => { |
| fn_call_span |
| } |
| UseSpans::FnSelfUse { var_span, .. } => var_span, |
| } |
| } |
| |
| pub(super) fn generator_kind(self) -> Option<GeneratorKind> { |
| match self { |
| UseSpans::ClosureUse { generator_kind, .. } => generator_kind, |
| _ => None, |
| } |
| } |
| |
| /// Add a span label to the arguments of the closure, if it exists. |
| pub(super) fn args_subdiag( |
| self, |
| err: &mut Diagnostic, |
| f: impl FnOnce(Span) -> CaptureArgLabel, |
| ) { |
| if let UseSpans::ClosureUse { args_span, .. } = self { |
| err.subdiagnostic(f(args_span)); |
| } |
| } |
| |
| /// Add a span label to the use of the captured variable, if it exists. |
| /// only adds label to the `path_span` |
| pub(super) fn var_path_only_subdiag( |
| self, |
| err: &mut Diagnostic, |
| action: crate::InitializationRequiringAction, |
| ) { |
| use crate::InitializationRequiringAction::*; |
| use CaptureVarPathUseCause::*; |
| if let UseSpans::ClosureUse { generator_kind, path_span, .. } = self { |
| match generator_kind { |
| Some(_) => { |
| err.subdiagnostic(match action { |
| Borrow => BorrowInGenerator { path_span }, |
| MatchOn | Use => UseInGenerator { path_span }, |
| Assignment => AssignInGenerator { path_span }, |
| PartialAssignment => AssignPartInGenerator { path_span }, |
| }); |
| } |
| None => { |
| err.subdiagnostic(match action { |
| Borrow => BorrowInClosure { path_span }, |
| MatchOn | Use => UseInClosure { path_span }, |
| Assignment => AssignInClosure { path_span }, |
| PartialAssignment => AssignPartInClosure { path_span }, |
| }); |
| } |
| } |
| } |
| } |
| |
| /// Add a subdiagnostic to the use of the captured variable, if it exists. |
| pub(super) fn var_subdiag( |
| self, |
| handler: Option<&rustc_errors::Handler>, |
| err: &mut Diagnostic, |
| kind: Option<rustc_middle::mir::BorrowKind>, |
| f: impl FnOnce(Option<GeneratorKind>, Span) -> CaptureVarCause, |
| ) { |
| if let UseSpans::ClosureUse { generator_kind, capture_kind_span, path_span, .. } = self { |
| if capture_kind_span != path_span { |
| err.subdiagnostic(match kind { |
| Some(kd) => match kd { |
| rustc_middle::mir::BorrowKind::Shared |
| | rustc_middle::mir::BorrowKind::Shallow |
| | rustc_middle::mir::BorrowKind::Unique => { |
| CaptureVarKind::Immut { kind_span: capture_kind_span } |
| } |
| |
| rustc_middle::mir::BorrowKind::Mut { .. } => { |
| CaptureVarKind::Mut { kind_span: capture_kind_span } |
| } |
| }, |
| None => CaptureVarKind::Move { kind_span: capture_kind_span }, |
| }); |
| }; |
| let diag = f(generator_kind, path_span); |
| match handler { |
| Some(hd) => err.eager_subdiagnostic(hd, diag), |
| None => err.subdiagnostic(diag), |
| }; |
| } |
| } |
| |
| /// Returns `false` if this place is not used in a closure. |
| pub(super) fn for_closure(&self) -> bool { |
| match *self { |
| UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_none(), |
| _ => false, |
| } |
| } |
| |
| /// Returns `false` if this place is not used in a generator. |
| pub(super) fn for_generator(&self) -> bool { |
| match *self { |
| UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_some(), |
| _ => false, |
| } |
| } |
| |
| pub(super) fn or_else<F>(self, if_other: F) -> Self |
| where |
| F: FnOnce() -> Self, |
| { |
| match self { |
| closure @ UseSpans::ClosureUse { .. } => closure, |
| UseSpans::PatUse(_) | UseSpans::OtherUse(_) => if_other(), |
| fn_self @ UseSpans::FnSelfUse { .. } => fn_self, |
| } |
| } |
| } |
| |
| pub(super) enum BorrowedContentSource<'tcx> { |
| DerefRawPointer, |
| DerefMutableRef, |
| DerefSharedRef, |
| OverloadedDeref(Ty<'tcx>), |
| OverloadedIndex(Ty<'tcx>), |
| } |
| |
| impl<'tcx> BorrowedContentSource<'tcx> { |
| pub(super) fn describe_for_unnamed_place(&self, tcx: TyCtxt<'_>) -> String { |
| match *self { |
| BorrowedContentSource::DerefRawPointer => "a raw pointer".to_string(), |
| BorrowedContentSource::DerefSharedRef => "a shared reference".to_string(), |
| BorrowedContentSource::DerefMutableRef => "a mutable reference".to_string(), |
| BorrowedContentSource::OverloadedDeref(ty) => ty |
| .ty_adt_def() |
| .and_then(|adt| match tcx.get_diagnostic_name(adt.did())? { |
| name @ (sym::Rc | sym::Arc) => Some(format!("an `{name}`")), |
| _ => None, |
| }) |
| .unwrap_or_else(|| format!("dereference of `{ty}`")), |
| BorrowedContentSource::OverloadedIndex(ty) => format!("index of `{ty}`"), |
| } |
| } |
| |
| pub(super) fn describe_for_named_place(&self) -> Option<&'static str> { |
| match *self { |
| BorrowedContentSource::DerefRawPointer => Some("raw pointer"), |
| BorrowedContentSource::DerefSharedRef => Some("shared reference"), |
| BorrowedContentSource::DerefMutableRef => Some("mutable reference"), |
| // Overloaded deref and index operators should be evaluated into a |
| // temporary. So we don't need a description here. |
| BorrowedContentSource::OverloadedDeref(_) |
| | BorrowedContentSource::OverloadedIndex(_) => None, |
| } |
| } |
| |
| pub(super) fn describe_for_immutable_place(&self, tcx: TyCtxt<'_>) -> String { |
| match *self { |
| BorrowedContentSource::DerefRawPointer => "a `*const` pointer".to_string(), |
| BorrowedContentSource::DerefSharedRef => "a `&` reference".to_string(), |
| BorrowedContentSource::DerefMutableRef => { |
| bug!("describe_for_immutable_place: DerefMutableRef isn't immutable") |
| } |
| BorrowedContentSource::OverloadedDeref(ty) => ty |
| .ty_adt_def() |
| .and_then(|adt| match tcx.get_diagnostic_name(adt.did())? { |
| name @ (sym::Rc | sym::Arc) => Some(format!("an `{name}`")), |
| _ => None, |
| }) |
| .unwrap_or_else(|| format!("dereference of `{ty}`")), |
| BorrowedContentSource::OverloadedIndex(ty) => format!("an index of `{ty}`"), |
| } |
| } |
| |
| fn from_call(func: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Self> { |
| match *func.kind() { |
| ty::FnDef(def_id, substs) => { |
| let trait_id = tcx.trait_of_item(def_id)?; |
| |
| let lang_items = tcx.lang_items(); |
| if Some(trait_id) == lang_items.deref_trait() |
| || Some(trait_id) == lang_items.deref_mut_trait() |
| { |
| Some(BorrowedContentSource::OverloadedDeref(substs.type_at(0))) |
| } else if Some(trait_id) == lang_items.index_trait() |
| || Some(trait_id) == lang_items.index_mut_trait() |
| { |
| Some(BorrowedContentSource::OverloadedIndex(substs.type_at(0))) |
| } else { |
| None |
| } |
| } |
| _ => None, |
| } |
| } |
| } |
| |
| ///helper struct for explain_captures() |
| struct CapturedMessageOpt { |
| is_partial_move: bool, |
| is_loop_message: bool, |
| is_move_msg: bool, |
| is_loop_move: bool, |
| maybe_reinitialized_locations_is_empty: bool, |
| } |
| |
| impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { |
| /// Finds the spans associated to a move or copy of move_place at location. |
| pub(super) fn move_spans( |
| &self, |
| moved_place: PlaceRef<'tcx>, // Could also be an upvar. |
| location: Location, |
| ) -> UseSpans<'tcx> { |
| use self::UseSpans::*; |
| |
| let Some(stmt) = self.body[location.block].statements.get(location.statement_index) else { |
| return OtherUse(self.body.source_info(location).span); |
| }; |
| |
| debug!("move_spans: moved_place={:?} location={:?} stmt={:?}", moved_place, location, stmt); |
| if let StatementKind::Assign(box (_, Rvalue::Aggregate(kind, places))) = &stmt.kind |
| && let AggregateKind::Closure(def_id, _) | AggregateKind::Generator(def_id, _, _) = **kind |
| { |
| debug!("move_spans: def_id={:?} places={:?}", def_id, places); |
| let def_id = def_id.expect_local(); |
| if let Some((args_span, generator_kind, capture_kind_span, path_span)) = |
| self.closure_span(def_id, moved_place, places) |
| { |
| return ClosureUse { |
| generator_kind, |
| args_span, |
| capture_kind_span, |
| path_span, |
| }; |
| } |
| } |
| |
| // StatementKind::FakeRead only contains a def_id if they are introduced as a result |
| // of pattern matching within a closure. |
| if let StatementKind::FakeRead(box (cause, place)) = stmt.kind { |
| match cause { |
| FakeReadCause::ForMatchedPlace(Some(closure_def_id)) |
| | FakeReadCause::ForLet(Some(closure_def_id)) => { |
| debug!("move_spans: def_id={:?} place={:?}", closure_def_id, place); |
| let places = &[Operand::Move(place)]; |
| if let Some((args_span, generator_kind, capture_kind_span, path_span)) = |
| self.closure_span(closure_def_id, moved_place, IndexSlice::from_raw(places)) |
| { |
| return ClosureUse { |
| generator_kind, |
| args_span, |
| capture_kind_span, |
| path_span, |
| }; |
| } |
| } |
| _ => {} |
| } |
| } |
| |
| let normal_ret = |
| if moved_place.projection.iter().any(|p| matches!(p, ProjectionElem::Downcast(..))) { |
| PatUse(stmt.source_info.span) |
| } else { |
| OtherUse(stmt.source_info.span) |
| }; |
| |
| // We are trying to find MIR of the form: |
| // ``` |
| // _temp = _moved_val; |
| // ... |
| // FnSelfCall(_temp, ...) |
| // ``` |
| // |
| // where `_moved_val` is the place we generated the move error for, |
| // `_temp` is some other local, and `FnSelfCall` is a function |
| // that has a `self` parameter. |
| |
| let target_temp = match stmt.kind { |
| StatementKind::Assign(box (temp, _)) if temp.as_local().is_some() => { |
| temp.as_local().unwrap() |
| } |
| _ => return normal_ret, |
| }; |
| |
| debug!("move_spans: target_temp = {:?}", target_temp); |
| |
| if let Some(Terminator { |
| kind: TerminatorKind::Call { fn_span, from_hir_call, .. }, .. |
| }) = &self.body[location.block].terminator |
| { |
| let Some((method_did, method_substs)) = |
| rustc_middle::util::find_self_call( |
| self.infcx.tcx, |
| &self.body, |
| target_temp, |
| location.block, |
| ) |
| else { |
| return normal_ret; |
| }; |
| |
| let kind = call_kind( |
| self.infcx.tcx, |
| self.param_env, |
| method_did, |
| method_substs, |
| *fn_span, |
| *from_hir_call, |
| Some(self.infcx.tcx.fn_arg_names(method_did)[0]), |
| ); |
| |
| return FnSelfUse { |
| var_span: stmt.source_info.span, |
| fn_call_span: *fn_span, |
| fn_span: self.infcx.tcx.def_span(method_did), |
| kind, |
| }; |
| } |
| normal_ret |
| } |
| |
| /// Finds the span of arguments of a closure (within `maybe_closure_span`) |
| /// and its usage of the local assigned at `location`. |
| /// This is done by searching in statements succeeding `location` |
| /// and originating from `maybe_closure_span`. |
| pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans<'tcx> { |
| use self::UseSpans::*; |
| debug!("borrow_spans: use_span={:?} location={:?}", use_span, location); |
| |
| let target = match self.body[location.block].statements.get(location.statement_index) { |
| Some(Statement { kind: StatementKind::Assign(box (place, _)), .. }) => { |
| if let Some(local) = place.as_local() { |
| local |
| } else { |
| return OtherUse(use_span); |
| } |
| } |
| _ => return OtherUse(use_span), |
| }; |
| |
| if self.body.local_kind(target) != LocalKind::Temp { |
| // operands are always temporaries. |
| return OtherUse(use_span); |
| } |
| |
| // drop and replace might have moved the assignment to the next block |
| let maybe_additional_statement = |
| if let TerminatorKind::Drop { target: drop_target, .. } = |
| self.body[location.block].terminator().kind |
| { |
| self.body[drop_target].statements.first() |
| } else { |
| None |
| }; |
| |
| let statements = |
| self.body[location.block].statements[location.statement_index + 1..].iter(); |
| |
| for stmt in statements.chain(maybe_additional_statement) { |
| if let StatementKind::Assign(box (_, Rvalue::Aggregate(kind, places))) = &stmt.kind { |
| let (&def_id, is_generator) = match kind { |
| box AggregateKind::Closure(def_id, _) => (def_id, false), |
| box AggregateKind::Generator(def_id, _, _) => (def_id, true), |
| _ => continue, |
| }; |
| let def_id = def_id.expect_local(); |
| |
| debug!( |
| "borrow_spans: def_id={:?} is_generator={:?} places={:?}", |
| def_id, is_generator, places |
| ); |
| if let Some((args_span, generator_kind, capture_kind_span, path_span)) = |
| self.closure_span(def_id, Place::from(target).as_ref(), places) |
| { |
| return ClosureUse { generator_kind, args_span, capture_kind_span, path_span }; |
| } else { |
| return OtherUse(use_span); |
| } |
| } |
| |
| if use_span != stmt.source_info.span { |
| break; |
| } |
| } |
| |
| OtherUse(use_span) |
| } |
| |
| /// Finds the spans of a captured place within a closure or generator. |
| /// The first span is the location of the use resulting in the capture kind of the capture |
| /// The second span is the location the use resulting in the captured path of the capture |
| fn closure_span( |
| &self, |
| def_id: LocalDefId, |
| target_place: PlaceRef<'tcx>, |
| places: &IndexSlice<FieldIdx, Operand<'tcx>>, |
| ) -> Option<(Span, Option<GeneratorKind>, Span, Span)> { |
| debug!( |
| "closure_span: def_id={:?} target_place={:?} places={:?}", |
| def_id, target_place, places |
| ); |
| let hir_id = self.infcx.tcx.hir().local_def_id_to_hir_id(def_id); |
| let expr = &self.infcx.tcx.hir().expect_expr(hir_id).kind; |
| debug!("closure_span: hir_id={:?} expr={:?}", hir_id, expr); |
| if let hir::ExprKind::Closure(&hir::Closure { body, fn_decl_span, .. }) = expr { |
| for (captured_place, place) in |
| self.infcx.tcx.closure_captures(def_id).iter().zip(places) |
| { |
| match place { |
| Operand::Copy(place) | Operand::Move(place) |
| if target_place == place.as_ref() => |
| { |
| debug!("closure_span: found captured local {:?}", place); |
| let body = self.infcx.tcx.hir().body(body); |
| let generator_kind = body.generator_kind(); |
| |
| return Some(( |
| fn_decl_span, |
| generator_kind, |
| captured_place.get_capture_kind_span(self.infcx.tcx), |
| captured_place.get_path_span(self.infcx.tcx), |
| )); |
| } |
| _ => {} |
| } |
| } |
| } |
| None |
| } |
| |
| /// Helper to retrieve span(s) of given borrow from the current MIR |
| /// representation |
| pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans<'tcx> { |
| let span = self.body.source_info(borrow.reserve_location).span; |
| self.borrow_spans(span, borrow.reserve_location) |
| } |
| |
| fn explain_captures( |
| &mut self, |
| err: &mut Diagnostic, |
| span: Span, |
| move_span: Span, |
| move_spans: UseSpans<'tcx>, |
| moved_place: Place<'tcx>, |
| msg_opt: CapturedMessageOpt, |
| ) { |
| let CapturedMessageOpt { |
| is_partial_move: is_partial, |
| is_loop_message, |
| is_move_msg, |
| is_loop_move, |
| maybe_reinitialized_locations_is_empty, |
| } = msg_opt; |
| if let UseSpans::FnSelfUse { var_span, fn_call_span, fn_span, kind } = move_spans { |
| let place_name = self |
| .describe_place(moved_place.as_ref()) |
| .map(|n| format!("`{n}`")) |
| .unwrap_or_else(|| "value".to_owned()); |
| match kind { |
| CallKind::FnCall { fn_trait_id, .. } |
| if Some(fn_trait_id) == self.infcx.tcx.lang_items().fn_once_trait() => |
| { |
| err.subdiagnostic(CaptureReasonLabel::Call { |
| fn_call_span, |
| place_name: &place_name, |
| is_partial, |
| is_loop_message, |
| }); |
| err.subdiagnostic(CaptureReasonNote::FnOnceMoveInCall { var_span }); |
| } |
| CallKind::Operator { self_arg, .. } => { |
| let self_arg = self_arg.unwrap(); |
| err.subdiagnostic(CaptureReasonLabel::OperatorUse { |
| fn_call_span, |
| place_name: &place_name, |
| is_partial, |
| is_loop_message, |
| }); |
| if self.fn_self_span_reported.insert(fn_span) { |
| err.subdiagnostic(CaptureReasonNote::LhsMoveByOperator { |
| span: self_arg.span, |
| }); |
| } |
| } |
| CallKind::Normal { self_arg, desugaring, method_did, method_substs } => { |
| let self_arg = self_arg.unwrap(); |
| let tcx = self.infcx.tcx; |
| if let Some((CallDesugaringKind::ForLoopIntoIter, _)) = desugaring { |
| let ty = moved_place.ty(self.body, tcx).ty; |
| let suggest = match tcx.get_diagnostic_item(sym::IntoIterator) { |
| Some(def_id) => type_known_to_meet_bound_modulo_regions( |
| &self.infcx, |
| self.param_env, |
| tcx.mk_imm_ref(tcx.lifetimes.re_erased, ty), |
| def_id, |
| ), |
| _ => false, |
| }; |
| if suggest { |
| err.subdiagnostic(CaptureReasonSuggest::IterateSlice { |
| ty, |
| span: move_span.shrink_to_lo(), |
| }); |
| } |
| |
| err.subdiagnostic(CaptureReasonLabel::ImplicitCall { |
| fn_call_span, |
| place_name: &place_name, |
| is_partial, |
| is_loop_message, |
| }); |
| // If the moved place was a `&mut` ref, then we can |
| // suggest to reborrow it where it was moved, so it |
| // will still be valid by the time we get to the usage. |
| if let ty::Ref(_, _, hir::Mutability::Mut) = |
| moved_place.ty(self.body, self.infcx.tcx).ty.kind() |
| { |
| // If we are in a loop this will be suggested later. |
| if !is_loop_move { |
| err.span_suggestion_verbose( |
| move_span.shrink_to_lo(), |
| format!( |
| "consider creating a fresh reborrow of {} here", |
| self.describe_place(moved_place.as_ref()) |
| .map(|n| format!("`{n}`")) |
| .unwrap_or_else(|| "the mutable reference".to_string()), |
| ), |
| "&mut *", |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } else { |
| if let Some((CallDesugaringKind::Await, _)) = desugaring { |
| err.subdiagnostic(CaptureReasonLabel::Await { |
| fn_call_span, |
| place_name: &place_name, |
| is_partial, |
| is_loop_message, |
| }); |
| } else { |
| err.subdiagnostic(CaptureReasonLabel::MethodCall { |
| fn_call_span, |
| place_name: &place_name, |
| is_partial, |
| is_loop_message, |
| }); |
| } |
| // Erase and shadow everything that could be passed to the new infcx. |
| let ty = moved_place.ty(self.body, tcx).ty; |
| |
| if let ty::Adt(def, substs) = ty.kind() |
| && Some(def.did()) == tcx.lang_items().pin_type() |
| && let ty::Ref(_, _, hir::Mutability::Mut) = substs.type_at(0).kind() |
| && let self_ty = self.infcx.instantiate_binder_with_fresh_vars( |
| fn_call_span, |
| LateBoundRegionConversionTime::FnCall, |
| tcx.fn_sig(method_did).subst(tcx, method_substs).input(0), |
| ) |
| && self.infcx.can_eq(self.param_env, ty, self_ty) |
| { |
| err.eager_subdiagnostic( |
| &self.infcx.tcx.sess.parse_sess.span_diagnostic, |
| CaptureReasonSuggest::FreshReborrow { |
| span: fn_call_span.shrink_to_lo(), |
| }); |
| } |
| if let Some(clone_trait) = tcx.lang_items().clone_trait() |
| && let trait_ref = ty::TraitRef::new(tcx, clone_trait, [ty]) |
| && let o = Obligation::new( |
| tcx, |
| ObligationCause::dummy(), |
| self.param_env, |
| ty::Binder::dummy(trait_ref), |
| ) |
| && self.infcx.predicate_must_hold_modulo_regions(&o) |
| { |
| err.span_suggestion_verbose( |
| fn_call_span.shrink_to_lo(), |
| "you can `clone` the value and consume it, but this might not be \ |
| your desired behavior", |
| "clone().".to_string(), |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| // Avoid pointing to the same function in multiple different |
| // error messages. |
| if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span) { |
| let func = tcx.def_path_str(method_did); |
| err.subdiagnostic(CaptureReasonNote::FuncTakeSelf { |
| func, |
| place_name, |
| span: self_arg.span, |
| }); |
| } |
| let parent_did = tcx.parent(method_did); |
| let parent_self_ty = |
| matches!(tcx.def_kind(parent_did), rustc_hir::def::DefKind::Impl { .. }) |
| .then_some(parent_did) |
| .and_then(|did| match tcx.type_of(did).subst_identity().kind() { |
| ty::Adt(def, ..) => Some(def.did()), |
| _ => None, |
| }); |
| let is_option_or_result = parent_self_ty.is_some_and(|def_id| { |
| matches!(tcx.get_diagnostic_name(def_id), Some(sym::Option | sym::Result)) |
| }); |
| if is_option_or_result && maybe_reinitialized_locations_is_empty { |
| err.subdiagnostic(CaptureReasonLabel::BorrowContent { var_span }); |
| } |
| } |
| // Other desugarings takes &self, which cannot cause a move |
| _ => {} |
| } |
| } else { |
| if move_span != span || is_loop_message { |
| err.subdiagnostic(CaptureReasonLabel::MovedHere { |
| move_span, |
| is_partial, |
| is_move_msg, |
| is_loop_message, |
| }); |
| } |
| // If the move error occurs due to a loop, don't show |
| // another message for the same span |
| if !is_loop_message { |
| move_spans.var_subdiag(None, err, None, |kind, var_span| match kind { |
| Some(_) => CaptureVarCause::PartialMoveUseInGenerator { var_span, is_partial }, |
| None => CaptureVarCause::PartialMoveUseInClosure { var_span, is_partial }, |
| }) |
| } |
| } |
| } |
| } |
