1//! Borrow checker diagnostics.23use std::collections::BTreeMap;45use rustc_abi::{FieldIdx, VariantIdx};6use rustc_data_structures::fx::FxIndexMap;7use rustc_errors::formatting::DiagMessageAddArg;8use rustc_errors::{Applicability, Diag, DiagMessage, EmissionGuarantee, MultiSpan, listify, msg};9use rustc_hir::def::{CtorKind, Namespace};10use rustc_hir::{11    self as hir, CoroutineKind, GenericBound, LangItem, WhereBoundPredicate, WherePredicateKind,12};13use rustc_index::{IndexSlice, IndexVec};14use rustc_infer::infer::{BoundRegionConversionTime, NllRegionVariableOrigin};15use rustc_infer::traits::SelectionError;16use rustc_middle::mir::{17    AggregateKind, CallSource, ConstOperand, ConstraintCategory, FakeReadCause, Local, LocalInfo,18    LocalKind, Location, Operand, Place, PlaceRef, PlaceTy, ProjectionElem, Rvalue, Statement,19    StatementKind, Terminator, TerminatorKind, VarDebugInfoContents, find_self_call,20};21use rustc_middle::ty::print::Print;22use rustc_middle::ty::{self, Ty, TyCtxt};23use rustc_middle::{bug, span_bug};24use rustc_mir_dataflow::move_paths::{InitLocation, LookupResult, MoveOutIndex};25use rustc_span::def_id::LocalDefId;26use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, Spanned, Symbol, sym};27use rustc_trait_selection::error_reporting::InferCtxtErrorExt;28use rustc_trait_selection::error_reporting::traits::call_kind::{CallDesugaringKind, call_kind};29use rustc_trait_selection::infer::InferCtxtExt;30use rustc_trait_selection::traits::{31    FulfillmentError, FulfillmentErrorCode, type_known_to_meet_bound_modulo_regions,32};33use tracing::debug;3435use super::MirBorrowckCtxt;36use super::borrow_set::BorrowData;37use crate::constraints::OutlivesConstraint;38use crate::nll::ConstraintDescription;39use crate::session_diagnostics::{40    CaptureArgLabel, CaptureReasonLabel, CaptureReasonNote, CaptureReasonSuggest, CaptureVarCause,41    CaptureVarKind, CaptureVarPathUseCause, OnClosureNote,42};4344mod find_all_local_uses;45mod find_use;46mod outlives_suggestion;47mod region_name;48mod var_name;4950mod bound_region_errors;51mod conflict_errors;52mod explain_borrow;53mod move_errors;54mod mutability_errors;55mod opaque_types;56mod region_errors;5758pub(crate) use bound_region_errors::{ToUniverseInfo, UniverseInfo};59pub(crate) use move_errors::{IllegalMoveOriginKind, MoveError};60pub(crate) use mutability_errors::AccessKind;61pub(crate) use outlives_suggestion::OutlivesSuggestionBuilder;62pub(crate) use region_errors::{ErrorConstraintInfo, RegionErrorKind, RegionErrors};63pub(crate) use region_name::{RegionName, RegionNameSource};64pub(crate) use rustc_trait_selection::error_reporting::traits::call_kind::CallKind;6566pub(super) struct DescribePlaceOpt {67    including_downcast: bool,6869    /// Enable/Disable tuple fields.70    /// For example `x` tuple. if it's `true` `x.0`. Otherwise `x`71    including_tuple_field: bool,72}7374pub(super) struct IncludingTupleField(pub(super) bool);7576enum BufferedDiag<'infcx> {77    Error(Diag<'infcx>),78    NonError(Diag<'infcx, ()>),79}8081impl<'infcx> BufferedDiag<'infcx> {82    fn sort_span(&self) -> Span {83        match self {84            BufferedDiag::Error(diag) => diag.sort_span,85            BufferedDiag::NonError(diag) => diag.sort_span,86        }87    }88}8990#[derive(Default)]91pub(crate) struct BorrowckDiagnosticsBuffer<'infcx, 'tcx> {92    /// This field keeps track of move errors that are to be reported for given move indices.93    ///94    /// There are situations where many errors can be reported for a single move out (see95    /// #53807) and we want only the best of those errors.96    ///97    /// The `report_use_of_moved_or_uninitialized` function checks this map and replaces the98    /// diagnostic (if there is one) if the `Place` of the error being reported is a prefix of99    /// the `Place` of the previous most diagnostic. This happens instead of buffering the100    /// error. Once all move errors have been reported, any diagnostics in this map are added101    /// to the buffer to be emitted.102    ///103    /// `BTreeMap` is used to preserve the order of insertions when iterating. This is necessary104    /// when errors in the map are being re-added to the error buffer so that errors with the105    /// same primary span come out in a consistent order.106    buffered_move_errors: BTreeMap<Vec<MoveOutIndex>, (PlaceRef<'tcx>, Diag<'infcx>)>,107108    buffered_mut_errors: FxIndexMap<Span, (Diag<'infcx>, usize)>,109110    /// Buffer of diagnostics to be reported. A mixture of error and non-error diagnostics.111    buffered_diags: Vec<BufferedDiag<'infcx>>,112}113114impl<'infcx, 'tcx> BorrowckDiagnosticsBuffer<'infcx, 'tcx> {115    pub(crate) fn buffer_non_error(&mut self, diag: Diag<'infcx, ()>) {116        self.buffered_diags.push(BufferedDiag::NonError(diag));117    }118}119120impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {121    pub(crate) fn buffer_error(&mut self, diag: Diag<'infcx>) {122        self.diags_buffer.buffered_diags.push(BufferedDiag::Error(diag));123    }124125    pub(crate) fn buffer_non_error(&mut self, diag: Diag<'infcx, ()>) {126        self.diags_buffer.buffer_non_error(diag);127    }128129    pub(crate) fn buffer_move_error(130        &mut self,131        move_out_indices: Vec<MoveOutIndex>,132        place_and_err: (PlaceRef<'tcx>, Diag<'infcx>),133    ) -> bool {134        if let Some((_, diag)) =135            self.diags_buffer.buffered_move_errors.insert(move_out_indices, place_and_err)136        {137            // Cancel the old diagnostic so we don't ICE138            diag.cancel();139            false140        } else {141            true142        }143    }144145    pub(crate) fn get_buffered_mut_error(&mut self, span: Span) -> Option<(Diag<'infcx>, usize)> {146        // FIXME(#120456) - is `swap_remove` correct?147        self.diags_buffer.buffered_mut_errors.swap_remove(&span)148    }149150    pub(crate) fn buffer_mut_error(&mut self, span: Span, diag: Diag<'infcx>, count: usize) {151        self.diags_buffer.buffered_mut_errors.insert(span, (diag, count));152    }153154    pub(crate) fn emit_errors(&mut self) -> Option<ErrorGuaranteed> {155        let mut res = self.infcx.tainted_by_errors();156157        // Buffer any move errors that we collected and de-duplicated.158        for (_, (_, diag)) in std::mem::take(&mut self.diags_buffer.buffered_move_errors) {159            // We have already set tainted for this error, so just buffer it.160            self.buffer_error(diag);161        }162        for (_, (mut diag, count)) in std::mem::take(&mut self.diags_buffer.buffered_mut_errors) {163            if count > 10 {164                diag.note(format!("...and {} other attempted mutable borrows", count - 10));165            }166            self.buffer_error(diag);167        }168169        if !self.diags_buffer.buffered_diags.is_empty() {170            self.diags_buffer.buffered_diags.sort_by_key(|buffered_diag| buffered_diag.sort_span());171            for buffered_diag in self.diags_buffer.buffered_diags.drain(..) {172                match buffered_diag {173                    BufferedDiag::Error(diag) => res = Some(diag.emit()),174                    BufferedDiag::NonError(diag) => diag.emit(),175                }176            }177        }178179        res180    }181182    pub(crate) fn has_buffered_diags(&self) -> bool {183        self.diags_buffer.buffered_diags.is_empty()184    }185186    pub(crate) fn has_move_error(187        &self,188        move_out_indices: &[MoveOutIndex],189    ) -> Option<&(PlaceRef<'tcx>, Diag<'infcx>)> {190        self.diags_buffer.buffered_move_errors.get(move_out_indices)191    }192193    /// Uses `body.var_debug_info` to find the symbol194    fn local_name(&self, index: Local) -> Option<Symbol> {195        *self.local_names().get(index)?196    }197198    fn local_names(&self) -> &IndexSlice<Local, Option<Symbol>> {199        self.local_names.get_or_init(|| {200            let mut local_names = IndexVec::from_elem(None, &self.body.local_decls);201            for var_debug_info in &self.body.var_debug_info {202                if let VarDebugInfoContents::Place(place) = var_debug_info.value {203                    if let Some(local) = place.as_local() {204                        if let Some(prev_name) = local_names[local]205                            && var_debug_info.name != prev_name206                        {207                            span_bug!(208                                var_debug_info.source_info.span,209                                "local {:?} has many names (`{}` vs `{}`)",210                                local,211                                prev_name,212                                var_debug_info.name213                            );214                        }215                        local_names[local] = Some(var_debug_info.name);216                    }217                }218            }219            local_names220        })221    }222}223224impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {225    /// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure226    /// is moved after being invoked.227    ///228    /// ```text229    /// note: closure cannot be invoked more than once because it moves the variable `dict` out of230    ///       its environment231    ///   --> $DIR/issue-42065.rs:16:29232    ///    |233    /// LL |         for (key, value) in dict {234    ///    |                             ^^^^235    /// ```236    pub(super) fn add_moved_or_invoked_closure_note(237        &self,238        location: Location,239        place: PlaceRef<'tcx>,240        diag: &mut Diag<'infcx>,241    ) -> bool {242        debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);243        let mut target = place.local_or_deref_local();244        for stmt in &self.body[location.block].statements[location.statement_index..] {245            debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target);246            if let StatementKind::Assign(box (into, Rvalue::Use(from, _))) = &stmt.kind {247                debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from);248                match from {249                    Operand::Copy(place) | Operand::Move(place)250                        if target == place.local_or_deref_local() =>251                    {252                        target = into.local_or_deref_local()253                    }254                    _ => {}255                }256            }257        }258259        // Check if we are attempting to call a closure after it has been invoked.260        let terminator = self.body[location.block].terminator();261        debug!("add_moved_or_invoked_closure_note: terminator={:?}", terminator);262        if let TerminatorKind::Call {263            func: Operand::Constant(box ConstOperand { const_, .. }),264            args,265            ..266        } = &terminator.kind267            && let ty::FnDef(id, _) = *const_.ty().kind()268        {269            debug!("add_moved_or_invoked_closure_note: id={:?}", id);270            if self.infcx.tcx.is_lang_item(self.infcx.tcx.parent(id), LangItem::FnOnce) {271                let closure = match args.first() {272                    Some(Spanned { node: Operand::Copy(place) | Operand::Move(place), .. })273                        if target == place.local_or_deref_local() =>274                    {275                        place.local_or_deref_local().unwrap()276                    }277                    _ => return false,278                };279280                debug!("add_moved_or_invoked_closure_note: closure={:?}", closure);281                if let ty::Closure(did, _) = self.body.local_decls[closure].ty.kind() {282                    let did = did.expect_local();283                    if let Some((span, hir_place)) = self.infcx.tcx.closure_kind_origin(did) {284                        diag.subdiagnostic(OnClosureNote::InvokedTwice {285                            place_name: &ty::place_to_string_for_capture(self.infcx.tcx, hir_place),286                            span: *span,287                        });288                        return true;289                    }290                }291            }292        }293294        // Check if we are just moving a closure after it has been invoked.295        if let Some(target) = target296            && let ty::Closure(did, _) = self.body.local_decls[target].ty.kind()297        {298            let did = did.expect_local();299            if let Some((span, hir_place)) = self.infcx.tcx.closure_kind_origin(did) {300                diag.subdiagnostic(OnClosureNote::MovedTwice {301                    place_name: &ty::place_to_string_for_capture(self.infcx.tcx, hir_place),302                    span: *span,303                });304                return true;305            }306        }307        false308    }309310    /// End-user visible description of `place` if one can be found.311    /// If the place is a temporary for instance, `"value"` will be returned.312    pub(super) fn describe_any_place(&self, place_ref: PlaceRef<'tcx>) -> String {313        match self.describe_place(place_ref) {314            Some(mut descr) => {315                // Surround descr with `backticks`.316                descr.reserve(2);317                descr.insert(0, '`');318                descr.push('`');319                descr320            }321            None => "value".to_string(),322        }323    }324325    /// End-user visible description of `place` if one can be found.326    /// If the place is a temporary for instance, `None` will be returned.327    pub(super) fn describe_place(&self, place_ref: PlaceRef<'tcx>) -> Option<String> {328        self.describe_place_with_options(329            place_ref,330            DescribePlaceOpt { including_downcast: false, including_tuple_field: true },331        )332    }333334    /// End-user visible description of `place` if one can be found. If the place is a temporary335    /// for instance, `None` will be returned.336    /// `IncludingDowncast` parameter makes the function return `None` if `ProjectionElem` is337    /// `Downcast` and `IncludingDowncast` is true338    pub(super) fn describe_place_with_options(339        &self,340        place: PlaceRef<'tcx>,341        opt: DescribePlaceOpt,342    ) -> Option<String> {343        let local = place.local;344        if self.body.local_decls[local]345            .source_info346            .span347            .in_external_macro(self.infcx.tcx.sess.source_map())348        {349            return None;350        }351352        let mut autoderef_index = None;353        let mut buf = String::new();354        let mut ok = self.append_local_to_string(local, &mut buf);355356        for (index, elem) in place.projection.into_iter().enumerate() {357            match elem {358                ProjectionElem::Deref => {359                    if index == 0 {360                        if self.body.local_decls[local].is_ref_for_guard() {361                            continue;362                        }363                        if let LocalInfo::StaticRef { def_id, .. } =364                            *self.body.local_decls[local].local_info()365                        {366                            buf.push_str(self.infcx.tcx.item_name(def_id).as_str());367                            ok = Ok(());368                            continue;369                        }370                    }371                    if let Some(field) = self.is_upvar_field_projection(PlaceRef {372                        local,373                        projection: place.projection.split_at(index + 1).0,374                    }) {375                        let var_index = field.index();376                        buf = self.upvars[var_index].to_string(self.infcx.tcx);377                        ok = Ok(());378                        if !self.upvars[var_index].is_by_ref() {379                            buf.insert(0, '*');380                        }381                    } else {382                        if autoderef_index.is_none() {383                            autoderef_index = match place.projection.iter().rposition(|elem| {384                                !matches!(385                                    elem,386                                    ProjectionElem::Deref | ProjectionElem::Downcast(..)387                                )388                            }) {389                                Some(index) => Some(index + 1),390                                None => Some(0),391                            };392                        }393                        if index >= autoderef_index.unwrap() {394                            buf.insert(0, '*');395                        }396                    }397                }398                ProjectionElem::Downcast(..) if opt.including_downcast => return None,399                ProjectionElem::Downcast(..) => (),400                ProjectionElem::OpaqueCast(..) => (),401                ProjectionElem::UnwrapUnsafeBinder(_) => (),402                ProjectionElem::Field(field, _ty) => {403                    // FIXME(project-rfc_2229#36): print capture precisely here.404                    if let Some(field) = self.is_upvar_field_projection(PlaceRef {405                        local,406                        projection: place.projection.split_at(index + 1).0,407                    }) {408                        buf = self.upvars[field.index()].to_string(self.infcx.tcx);409                        ok = Ok(());410                    } else {411                        let field_name = self.describe_field(412                            PlaceRef { local, projection: place.projection.split_at(index).0 },413                            *field,414                            IncludingTupleField(opt.including_tuple_field),415                        );416                        if let Some(field_name_str) = field_name {417                            buf.push('.');418                            buf.push_str(&field_name_str);419                        }420                    }421                }422                ProjectionElem::Index(index) => {423                    buf.push('[');424                    if self.append_local_to_string(*index, &mut buf).is_err() {425                        buf.push('_');426                    }427                    buf.push(']');428                }429                ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {430                    // Since it isn't possible to borrow an element on a particular index and431                    // then use another while the borrow is held, don't output indices details432                    // to avoid confusing the end-user433                    buf.push_str("[..]");434                }435            }436        }437        ok.ok().map(|_| buf)438    }439440    fn describe_name(&self, place: PlaceRef<'tcx>) -> Option<Symbol> {441        for elem in place.projection.into_iter() {442            match elem {443                ProjectionElem::Downcast(Some(name), _) => {444                    return Some(*name);445                }446                _ => {}447            }448        }449        None450    }451452    /// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have453    /// a name, or its name was generated by the compiler, then `Err` is returned454    fn append_local_to_string(&self, local: Local, buf: &mut String) -> Result<(), ()> {455        let decl = &self.body.local_decls[local];456        match self.local_name(local) {457            Some(name) if !decl.from_compiler_desugaring() => {458                buf.push_str(name.as_str());459                Ok(())460            }461            _ => Err(()),462        }463    }464465    /// End-user visible description of the `field`nth field of `base`466    fn describe_field(467        &self,468        place: PlaceRef<'tcx>,469        field: FieldIdx,470        including_tuple_field: IncludingTupleField,471    ) -> Option<String> {472        let place_ty = match place {473            PlaceRef { local, projection: [] } => PlaceTy::from_ty(self.body.local_decls[local].ty),474            PlaceRef { local, projection: [proj_base @ .., elem] } => match elem {475                ProjectionElem::Deref476                | ProjectionElem::Index(..)477                | ProjectionElem::ConstantIndex { .. }478                | ProjectionElem::Subslice { .. } => {479                    PlaceRef { local, projection: proj_base }.ty(self.body, self.infcx.tcx)480                }481                ProjectionElem::Downcast(..) => place.ty(self.body, self.infcx.tcx),482                ProjectionElem::OpaqueCast(ty) | ProjectionElem::UnwrapUnsafeBinder(ty) => {483                    PlaceTy::from_ty(*ty)484                }485                ProjectionElem::Field(_, field_type) => PlaceTy::from_ty(*field_type),486            },487        };488        self.describe_field_from_ty(489            place_ty.ty,490            field,491            place_ty.variant_index,492            including_tuple_field,493        )494    }495496    /// End-user visible description of the `field_index`nth field of `ty`497    fn describe_field_from_ty(498        &self,499        ty: Ty<'_>,500        field: FieldIdx,501        variant_index: Option<VariantIdx>,502        including_tuple_field: IncludingTupleField,503    ) -> Option<String> {504        if let Some(boxed_ty) = ty.boxed_ty() {505            // If the type is a box, the field is described from the boxed type506            self.describe_field_from_ty(boxed_ty, field, variant_index, including_tuple_field)507        } else {508            match *ty.kind() {509                ty::Adt(def, _) => {510                    let variant = if let Some(idx) = variant_index {511                        assert!(def.is_enum());512                        def.variant(idx)513                    } else {514                        def.non_enum_variant()515                    };516                    if !including_tuple_field.0 && variant.ctor_kind() == Some(CtorKind::Fn) {517                        return None;518                    }519                    Some(variant.fields[field].name.to_string())520                }521                ty::Tuple(_) => Some(field.index().to_string()),522                ty::Ref(_, ty, _) | ty::RawPtr(ty, _) => {523                    self.describe_field_from_ty(ty, field, variant_index, including_tuple_field)524                }525                ty::Array(ty, _) | ty::Slice(ty) => {526                    self.describe_field_from_ty(ty, field, variant_index, including_tuple_field)527                }528                ty::Closure(def_id, _) | ty::Coroutine(def_id, _) => {529                    // We won't be borrowck'ing here if the closure came from another crate,530                    // so it's safe to call `expect_local`.531                    //532                    // We know the field exists so it's safe to call operator[] and `unwrap` here.533                    let def_id = def_id.expect_local();534                    let var_id =535                        self.infcx.tcx.closure_captures(def_id)[field.index()].get_root_variable();536537                    Some(self.infcx.tcx.hir_name(var_id).to_string())538                }539                _ => {540                    // Might need a revision when the fields in trait RFC is implemented541                    // (https://github.com/rust-lang/rfcs/pull/1546)542                    bug!("End-user description not implemented for field access on `{:?}`", ty);543                }544            }545        }546    }547548    pub(super) fn borrowed_content_source(549        &self,550        deref_base: PlaceRef<'tcx>,551    ) -> BorrowedContentSource<'tcx> {552        let tcx = self.infcx.tcx;553554        // Look up the provided place and work out the move path index for it,555        // we'll use this to check whether it was originally from an overloaded556        // operator.557        match self.move_data.rev_lookup.find(deref_base) {558            LookupResult::Exact(mpi) | LookupResult::Parent(Some(mpi)) => {559                debug!("borrowed_content_source: mpi={:?}", mpi);560561                for i in &self.move_data.init_path_map[mpi] {562                    let init = &self.move_data.inits[*i];563                    debug!("borrowed_content_source: init={:?}", init);564                    // We're only interested in statements that initialized a value, not the565                    // initializations from arguments.566                    let InitLocation::Statement(loc) = init.location else { continue };567568                    let bbd = &self.body[loc.block];569                    let is_terminator = bbd.statements.len() == loc.statement_index;570                    debug!(571                        "borrowed_content_source: loc={:?} is_terminator={:?}",572                        loc, is_terminator,573                    );574                    if !is_terminator {575                        continue;576                    } else if let Some(Terminator {577                        kind:578                            TerminatorKind::Call {579                                func,580                                call_source: CallSource::OverloadedOperator,581                                ..582                            },583                        ..584                    }) = &bbd.terminator585                    {586                        if let Some(source) =587                            BorrowedContentSource::from_call(func.ty(self.body, tcx), tcx)588                        {589                            return source;590                        }591                    }592                }593            }594            // Base is a `static` so won't be from an overloaded operator595            _ => (),596        };597598        // If we didn't find an overloaded deref or index, then assume it's a599        // built in deref and check the type of the base.600        let base_ty = deref_base.ty(self.body, tcx).ty;601        if base_ty.is_raw_ptr() {602            BorrowedContentSource::DerefRawPointer603        } else if base_ty.is_mutable_ptr() {604            BorrowedContentSource::DerefMutableRef605        } else if base_ty.is_ref() {606            BorrowedContentSource::DerefSharedRef607        } else {608            // Custom type implementing `Deref` (e.g. `MyBox<T>`, `Rc<T>`, `Arc<T>`)609            // that wasn't detected via the MIR init trace above. This can happen610            // when the deref base is initialized by a regular statement rather than611            // a `TerminatorKind::Call` with `CallSource::OverloadedOperator`.612            BorrowedContentSource::OverloadedDeref(base_ty)613        }614    }615616    /// Return the name of the provided `Ty` (that must be a reference) with a synthesized lifetime617    /// name where required.618    pub(super) fn get_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {619        let mut p = ty::print::FmtPrinter::new(self.infcx.tcx, Namespace::TypeNS);620621        // We need to add synthesized lifetimes where appropriate. We do622        // this by hooking into the pretty printer and telling it to label the623        // lifetimes without names with the value `'0`.624        if let ty::Ref(region, ..) = ty.kind() {625            match region.kind() {626                ty::ReBound(_, ty::BoundRegion { kind: br, .. })627                | ty::RePlaceholder(ty::PlaceholderRegion {628                    bound: ty::BoundRegion { kind: br, .. },629                    ..630                }) => p.region_highlight_mode.highlighting_bound_region(br, counter),631                _ => {}632            }633        }634635        ty.print(&mut p).unwrap();636        p.into_buffer()637    }638639    /// Returns the name of the provided `Ty` (that must be a reference)'s region with a640    /// synthesized lifetime name where required.641    pub(super) fn get_region_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {642        let mut p = ty::print::FmtPrinter::new(self.infcx.tcx, Namespace::TypeNS);643644        let region = if let ty::Ref(region, ..) = ty.kind() {645            match region.kind() {646                ty::ReBound(_, ty::BoundRegion { kind: br, .. })647                | ty::RePlaceholder(ty::PlaceholderRegion {648                    bound: ty::BoundRegion { kind: br, .. },649                    ..650                }) => p.region_highlight_mode.highlighting_bound_region(br, counter),651                _ => {}652            }653            region654        } else {655            bug!("ty for annotation of borrow region is not a reference");656        };657658        region.print(&mut p).unwrap();659        p.into_buffer()660    }661662    /// Add a note to region errors and borrow explanations when higher-ranked regions in predicates663    /// implicitly introduce an "outlives `'static`" constraint.664    ///665    /// This is very similar to `fn suggest_static_lifetime_for_gat_from_hrtb` which handles this666    /// note for failed type tests instead of outlives errors.667    fn add_placeholder_from_predicate_note<G: EmissionGuarantee>(668        &self,669        diag: &mut Diag<'_, G>,670        path: &[OutlivesConstraint<'tcx>],671    ) {672        let tcx = self.infcx.tcx;673        let Some((gat_hir_id, generics)) = path.iter().find_map(|constraint| {674            let outlived = constraint.sub;675            if let Some(origin) = self.regioncx.definitions.get(outlived)676                && let NllRegionVariableOrigin::Placeholder(placeholder) = origin.origin677                && let Some(id) = placeholder.bound.kind.get_id()678                && let Some(placeholder_id) = id.as_local()679                && let gat_hir_id = tcx.local_def_id_to_hir_id(placeholder_id)680                && let Some(generics_impl) =681                    tcx.parent_hir_node(tcx.parent_hir_id(gat_hir_id)).generics()682            {683                Some((gat_hir_id, generics_impl))684            } else {685                None686            }687        }) else {688            return;689        };690691        // Look for the where-bound which introduces the placeholder.692        // As we're using the HIR, we need to handle both `for<'a> T: Trait<'a>`693        // and `T: for<'a> Trait`<'a>.694        for pred in generics.predicates {695            let WherePredicateKind::BoundPredicate(WhereBoundPredicate {696                bound_generic_params,697                bounds,698                ..699            }) = pred.kind700            else {701                continue;702            };703            if bound_generic_params704                .iter()705                .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == gat_hir_id)706                .is_some()707            {708                diag.span_note(pred.span, LIMITATION_NOTE);709                return;710            }711            for bound in bounds.iter() {712                if let GenericBound::Trait(bound) = bound {713                    if bound714                        .bound_generic_params715                        .iter()716                        .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == gat_hir_id)717                        .is_some()718                    {719                        diag.span_note(bound.span, LIMITATION_NOTE);720                        return;721                    }722                }723            }724        }725    }726727    /// Add a label to region errors and borrow explanations when outlives constraints arise from728    /// proving a type implements `Sized` or `Copy`.729    fn add_sized_or_copy_bound_info<G: EmissionGuarantee>(730        &self,731        err: &mut Diag<'_, G>,732        blamed_category: ConstraintCategory<'tcx>,733        path: &[OutlivesConstraint<'tcx>],734    ) {735        for sought_category in [ConstraintCategory::SizedBound, ConstraintCategory::CopyBound] {736            if sought_category != blamed_category737                && let Some(sought_constraint) = path.iter().find(|c| c.category == sought_category)738            {739                let label = format!(740                    "requirement occurs due to {}",741                    sought_category.description().trim_end()742                );743                err.span_label(sought_constraint.span, label);744            }745        }746    }747}748749/// The span(s) associated to a use of a place.750#[derive(Copy, Clone, PartialEq, Eq, Debug)]751pub(super) enum UseSpans<'tcx> {752    /// The access is caused by capturing a variable for a closure.753    ClosureUse {754        /// This is true if the captured variable was from a coroutine.755        closure_kind: hir::ClosureKind,756        /// The span of the args of the closure, including the `move` keyword if757        /// it's present.758        args_span: Span,759        /// The span of the use resulting in capture kind760        /// Check `ty::CaptureInfo` for more details761        capture_kind_span: Span,762        /// The span of the use resulting in the captured path763        /// Check `ty::CaptureInfo` for more details764        path_span: Span,765    },766    /// The access is caused by using a variable as the receiver of a method767    /// that takes 'self'768    FnSelfUse {769        /// The span of the variable being moved770        var_span: Span,771        /// The span of the method call on the variable772        fn_call_span: Span,773        /// The definition span of the method being called774        fn_span: Span,775        kind: CallKind<'tcx>,776    },777    /// This access is caused by a `match` or `if let` pattern.778    PatUse(Span),779    /// This access has a single span associated to it: common case.780    OtherUse(Span),781}782783impl UseSpans<'_> {784    pub(super) fn args_or_use(self) -> Span {785        match self {786            UseSpans::ClosureUse { args_span: span, .. }787            | UseSpans::PatUse(span)788            | UseSpans::OtherUse(span) => span,789            UseSpans::FnSelfUse { var_span, .. } => var_span,790        }791    }792793    /// Returns the span of `self`, in the case of a `ClosureUse` returns the `path_span`794    pub(super) fn var_or_use_path_span(self) -> Span {795        match self {796            UseSpans::ClosureUse { path_span: span, .. }797            | UseSpans::PatUse(span)798            | UseSpans::OtherUse(span) => span,799            UseSpans::FnSelfUse { var_span, .. } => var_span,800        }801    }802803    /// Returns the span of `self`, in the case of a `ClosureUse` returns the `capture_kind_span`804    pub(super) fn var_or_use(self) -> Span {805        match self {806            UseSpans::ClosureUse { capture_kind_span: span, .. }807            | UseSpans::PatUse(span)808            | UseSpans::OtherUse(span) => span,809            UseSpans::FnSelfUse { var_span, .. } => var_span,810        }811    }812813    // FIXME(coroutines): Make this just return the `ClosureKind` directly?814    pub(super) fn coroutine_kind(self) -> Option<CoroutineKind> {815        match self {816            UseSpans::ClosureUse {817                closure_kind: hir::ClosureKind::Coroutine(coroutine_kind),818                ..819            } => Some(coroutine_kind),820            _ => None,821        }822    }823824    /// Add a span label to the arguments of the closure, if it exists.825    pub(super) fn args_subdiag(self, err: &mut Diag<'_>, f: impl FnOnce(Span) -> CaptureArgLabel) {826        if let UseSpans::ClosureUse { args_span, .. } = self {827            err.subdiagnostic(f(args_span));828        }829    }830831    /// Add a span label to the use of the captured variable, if it exists.832    /// only adds label to the `path_span`833    pub(super) fn var_path_only_subdiag(834        self,835        err: &mut Diag<'_>,836        action: crate::InitializationRequiringAction,837    ) {838        use CaptureVarPathUseCause::*;839840        use crate::InitializationRequiringAction::*;841        if let UseSpans::ClosureUse { closure_kind, path_span, .. } = self {842            match closure_kind {843                hir::ClosureKind::Coroutine(_) => {844                    err.subdiagnostic(match action {845                        Borrow => BorrowInCoroutine { path_span },846                        MatchOn | Use => UseInCoroutine { path_span },847                        Assignment => AssignInCoroutine { path_span },848                        PartialAssignment => AssignPartInCoroutine { path_span },849                    });850                }851                hir::ClosureKind::Closure | hir::ClosureKind::CoroutineClosure(_) => {852                    err.subdiagnostic(match action {853                        Borrow => BorrowInClosure { path_span },854                        MatchOn | Use => UseInClosure { path_span },855                        Assignment => AssignInClosure { path_span },856                        PartialAssignment => AssignPartInClosure { path_span },857                    });858                }859            }860        }861    }862863    /// Add a subdiagnostic to the use of the captured variable, if it exists.864    pub(super) fn var_subdiag(865        self,866        err: &mut Diag<'_>,867        kind: Option<rustc_middle::mir::BorrowKind>,868        f: impl FnOnce(hir::ClosureKind, Span) -> CaptureVarCause,869    ) {870        if let UseSpans::ClosureUse { closure_kind, capture_kind_span, path_span, .. } = self {871            if capture_kind_span != path_span {872                err.subdiagnostic(match kind {873                    Some(kd) => match kd {874                        rustc_middle::mir::BorrowKind::Shared875                        | rustc_middle::mir::BorrowKind::Fake(_) => {876                            CaptureVarKind::Immut { kind_span: capture_kind_span }877                        }878879                        rustc_middle::mir::BorrowKind::Mut { .. } => {880                            CaptureVarKind::Mut { kind_span: capture_kind_span }881                        }882                    },883                    None => CaptureVarKind::Move { kind_span: capture_kind_span },884                });885            };886            let diag = f(closure_kind, path_span);887            err.subdiagnostic(diag);888        }889    }890891    /// Returns `false` if this place is not used in a closure.892    pub(super) fn for_closure(&self) -> bool {893        match *self {894            UseSpans::ClosureUse { closure_kind, .. } => {895                matches!(closure_kind, hir::ClosureKind::Closure)896            }897            _ => false,898        }899    }900901    /// Returns `false` if this place is not used in a coroutine.902    pub(super) fn for_coroutine(&self) -> bool {903        match *self {904            // FIXME(coroutines): Do we want this to apply to synthetic coroutines?905            UseSpans::ClosureUse { closure_kind, .. } => {906                matches!(closure_kind, hir::ClosureKind::Coroutine(..))907            }908            _ => false,909        }910    }911912    pub(super) fn or_else<F>(self, if_other: F) -> Self913    where914        F: FnOnce() -> Self,915    {916        match self {917            closure @ UseSpans::ClosureUse { .. } => closure,918            UseSpans::PatUse(_) | UseSpans::OtherUse(_) => if_other(),919            fn_self @ UseSpans::FnSelfUse { .. } => fn_self,920        }921    }922}923924pub(super) enum BorrowedContentSource<'tcx> {925    DerefRawPointer,926    DerefMutableRef,927    DerefSharedRef,928    OverloadedDeref(Ty<'tcx>),929    OverloadedIndex(Ty<'tcx>),930}931932impl<'tcx> BorrowedContentSource<'tcx> {933    pub(super) fn describe_for_unnamed_place(&self, tcx: TyCtxt<'_>) -> String {934        match *self {935            BorrowedContentSource::DerefRawPointer => "a raw pointer".to_string(),936            BorrowedContentSource::DerefSharedRef => "a shared reference".to_string(),937            BorrowedContentSource::DerefMutableRef => "a mutable reference".to_string(),938            BorrowedContentSource::OverloadedDeref(ty) => ty939                .ty_adt_def()940                .and_then(|adt| match tcx.get_diagnostic_name(adt.did())? {941                    name @ (sym::Rc | sym::Arc) => Some(format!("an `{name}`")),942                    _ => None,943                })944                .unwrap_or_else(|| format!("dereference of `{ty}`")),945            BorrowedContentSource::OverloadedIndex(ty) => format!("index of `{ty}`"),946        }947    }948949    pub(super) fn describe_for_named_place(&self) -> Option<&'static str> {950        match *self {951            BorrowedContentSource::DerefRawPointer => Some("raw pointer"),952            BorrowedContentSource::DerefSharedRef => Some("shared reference"),953            BorrowedContentSource::DerefMutableRef => Some("mutable reference"),954            // Overloaded deref and index operators should be evaluated into a955            // temporary. So we don't need a description here.956            BorrowedContentSource::OverloadedDeref(_)957            | BorrowedContentSource::OverloadedIndex(_) => None,958        }959    }960961    pub(super) fn describe_for_immutable_place(&self, tcx: TyCtxt<'_>) -> String {962        match *self {963            BorrowedContentSource::DerefRawPointer => "a `*const` pointer".to_string(),964            BorrowedContentSource::DerefSharedRef => "a `&` reference".to_string(),965            BorrowedContentSource::DerefMutableRef => {966                bug!("describe_for_immutable_place: DerefMutableRef isn't immutable")967            }968            BorrowedContentSource::OverloadedDeref(ty) => ty969                .ty_adt_def()970                .and_then(|adt| match tcx.get_diagnostic_name(adt.did())? {971                    name @ (sym::Rc | sym::Arc) => Some(format!("an `{name}`")),972                    _ => None,973                })974                .unwrap_or_else(|| format!("dereference of `{ty}`")),975            BorrowedContentSource::OverloadedIndex(ty) => format!("an index of `{ty}`"),976        }977    }978979    fn from_call(func: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Self> {980        match *func.kind() {981            ty::FnDef(def_id, args) => {982                let trait_id = tcx.trait_of_assoc(def_id)?;983984                if tcx.is_lang_item(trait_id, LangItem::Deref)985                    || tcx.is_lang_item(trait_id, LangItem::DerefMut)986                {987                    Some(BorrowedContentSource::OverloadedDeref(args.type_at(0)))988                } else if tcx.is_lang_item(trait_id, LangItem::Index)989                    || tcx.is_lang_item(trait_id, LangItem::IndexMut)990                {991                    Some(BorrowedContentSource::OverloadedIndex(args.type_at(0)))992                } else {993                    None994                }995            }996            _ => None,997        }998    }999}10001001/// Helper struct for `explain_captures`.1002struct CapturedMessageOpt {1003    is_partial_move: bool,1004    is_loop_message: bool,1005    is_move_msg: bool,1006    is_loop_move: bool,1007    has_suggest_reborrow: bool,1008    maybe_reinitialized_locations_is_empty: bool,1009}10101011/// Tracks whether [`MirBorrowckCtxt::explain_captures`] emitted a clone1012/// suggestion, so callers can avoid emitting redundant suggestions downstream.1013#[derive(Copy, Clone, PartialEq, Eq)]1014pub(super) enum CloneSuggestion {1015    Emitted,1016    NotEmitted,1017}10181019impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {1020    /// Finds the spans associated to a move or copy of move_place at location.1021    pub(super) fn move_spans(1022        &self,1023        moved_place: PlaceRef<'tcx>, // Could also be an upvar.1024        location: Location,1025    ) -> UseSpans<'tcx> {1026        use self::UseSpans::*;10271028        let Some(stmt) = self.body[location.block].statements.get(location.statement_index) else {1029            return OtherUse(self.body.source_info(location).span);1030        };10311032        debug!("move_spans: moved_place={:?} location={:?} stmt={:?}", moved_place, location, stmt);1033        if let StatementKind::Assign(box (_, Rvalue::Aggregate(kind, places))) = &stmt.kind1034            && let AggregateKind::Closure(def_id, _) | AggregateKind::Coroutine(def_id, _) = **kind1035        {1036            debug!("move_spans: def_id={:?} places={:?}", def_id, places);1037            let def_id = def_id.expect_local();1038            if let Some((args_span, closure_kind, capture_kind_span, path_span)) =1039                self.closure_span(def_id, moved_place, places)1040            {1041                return ClosureUse { closure_kind, args_span, capture_kind_span, path_span };1042            }1043        }10441045        // StatementKind::FakeRead only contains a def_id if they are introduced as a result1046        // of pattern matching within a closure.1047        if let StatementKind::FakeRead(box (cause, place)) = stmt.kind {1048            match cause {1049                FakeReadCause::ForMatchedPlace(Some(closure_def_id))1050                | FakeReadCause::ForLet(Some(closure_def_id)) => {1051                    debug!("move_spans: def_id={:?} place={:?}", closure_def_id, place);1052                    let places = &[Operand::Move(place)];1053                    if let Some((args_span, closure_kind, capture_kind_span, path_span)) =1054                        self.closure_span(closure_def_id, moved_place, IndexSlice::from_raw(places))1055                    {1056                        return ClosureUse {1057                            closure_kind,1058                            args_span,1059                            capture_kind_span,1060                            path_span,1061                        };1062                    }1063                }1064                _ => {}1065            }1066        }10671068        let normal_ret =1069            if moved_place.projection.iter().any(|p| matches!(p, ProjectionElem::Downcast(..))) {1070                PatUse(stmt.source_info.span)1071            } else {1072                OtherUse(stmt.source_info.span)1073            };10741075        // We are trying to find MIR of the form:1076        // ```1077        // _temp = _moved_val;1078        // ...1079        // FnSelfCall(_temp, ...)1080        // ```1081        //1082        // where `_moved_val` is the place we generated the move error for,1083        // `_temp` is some other local, and `FnSelfCall` is a function1084        // that has a `self` parameter.10851086        let target_temp = match stmt.kind {1087            StatementKind::Assign(box (temp, _)) if temp.as_local().is_some() => {1088                temp.as_local().unwrap()1089            }1090            _ => return normal_ret,1091        };10921093        debug!("move_spans: target_temp = {:?}", target_temp);10941095        if let Some(Terminator {1096            kind: TerminatorKind::Call { fn_span, call_source, .. }, ..1097        }) = &self.body[location.block].terminator1098        {1099            let Some((method_did, method_args)) =1100                find_self_call(self.infcx.tcx, self.body, target_temp, location.block)1101            else {1102                return normal_ret;1103            };11041105            let kind = call_kind(1106                self.infcx.tcx,1107                self.infcx.typing_env(self.infcx.param_env),1108                method_did,1109                method_args,1110                *fn_span,1111                call_source.from_hir_call(),1112                self.infcx.tcx.fn_arg_idents(method_did)[0],1113            );11141115            return FnSelfUse {1116                var_span: stmt.source_info.span,1117                fn_call_span: *fn_span,1118                fn_span: self.infcx.tcx.def_span(method_did),1119                kind,1120            };1121        }11221123        normal_ret1124    }11251126    /// Finds the span of arguments of a closure (within `maybe_closure_span`)1127    /// and its usage of the local assigned at `location`.1128    /// This is done by searching in statements succeeding `location`1129    /// and originating from `maybe_closure_span`.1130    pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans<'tcx> {1131        use self::UseSpans::*;1132        debug!("borrow_spans: use_span={:?} location={:?}", use_span, location);11331134        let Some(Statement { kind: StatementKind::Assign(box (place, _)), .. }) =1135            self.body[location.block].statements.get(location.statement_index)1136        else {1137            return OtherUse(use_span);1138        };1139        let Some(target) = place.as_local() else { return OtherUse(use_span) };11401141        if self.body.local_kind(target) != LocalKind::Temp {1142            // operands are always temporaries.1143            return OtherUse(use_span);1144        }11451146        // drop and replace might have moved the assignment to the next block1147        let maybe_additional_statement =1148            if let TerminatorKind::Drop { target: drop_target, .. } =1149                self.body[location.block].terminator().kind1150            {1151                self.body[drop_target].statements.first()1152            } else {1153                None1154            };11551156        let statements =1157            self.body[location.block].statements[location.statement_index + 1..].iter();11581159        for stmt in statements.chain(maybe_additional_statement) {1160            if let StatementKind::Assign(box (_, Rvalue::Aggregate(kind, places))) = &stmt.kind {1161                let (&def_id, is_coroutine) = match kind {1162                    box AggregateKind::Closure(def_id, _) => (def_id, false),1163                    box AggregateKind::Coroutine(def_id, _) => (def_id, true),1164                    _ => continue,1165                };1166                let def_id = def_id.expect_local();11671168                debug!(1169                    "borrow_spans: def_id={:?} is_coroutine={:?} places={:?}",1170                    def_id, is_coroutine, places1171                );1172                if let Some((args_span, closure_kind, capture_kind_span, path_span)) =1173                    self.closure_span(def_id, Place::from(target).as_ref(), places)1174                {1175                    return ClosureUse { closure_kind, args_span, capture_kind_span, path_span };1176                } else {1177                    return OtherUse(use_span);1178                }1179            }11801181            if use_span != stmt.source_info.span {1182                break;1183            }1184        }11851186        OtherUse(use_span)1187    }11881189    /// Finds the spans of a captured place within a closure or coroutine.1190    /// The first span is the location of the use resulting in the capture kind of the capture1191    /// The second span is the location the use resulting in the captured path of the capture1192    fn closure_span(1193        &self,1194        def_id: LocalDefId,1195        target_place: PlaceRef<'tcx>,1196        places: &IndexSlice<FieldIdx, Operand<'tcx>>,1197    ) -> Option<(Span, hir::ClosureKind, Span, Span)> {1198        debug!(1199            "closure_span: def_id={:?} target_place={:?} places={:?}",1200            def_id, target_place, places1201        );1202        let hir_id = self.infcx.tcx.local_def_id_to_hir_id(def_id);1203        let expr = &self.infcx.tcx.hir_expect_expr(hir_id).kind;1204        debug!("closure_span: hir_id={:?} expr={:?}", hir_id, expr);1205        if let &hir::ExprKind::Closure(&hir::Closure { kind, fn_decl_span, .. }) = expr {1206            for (captured_place, place) in1207                self.infcx.tcx.closure_captures(def_id).iter().zip(places)1208            {1209                match place {1210                    Operand::Copy(place) | Operand::Move(place)1211                        if target_place == place.as_ref() =>1212                    {1213                        debug!("closure_span: found captured local {:?}", place);1214                        return Some((1215                            fn_decl_span,1216                            kind,1217                            captured_place.get_capture_kind_span(self.infcx.tcx),1218                            captured_place.get_path_span(self.infcx.tcx),1219                        ));1220                    }1221                    _ => {}1222                }1223            }1224        }1225        None1226    }12271228    /// Helper to retrieve span(s) of given borrow from the current MIR1229    /// representation1230    pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans<'tcx> {1231        let span = self.body.source_info(borrow.reserve_location).span;1232        self.borrow_spans(span, borrow.reserve_location)1233    }12341235    fn explain_captures(1236        &mut self,1237        err: &mut Diag<'infcx>,1238        span: Span,1239        move_span: Span,1240        move_spans: UseSpans<'tcx>,1241        moved_place: Place<'tcx>,1242        msg_opt: CapturedMessageOpt,1243    ) -> CloneSuggestion {1244        let CapturedMessageOpt {1245            is_partial_move: is_partial,1246            is_loop_message,1247            is_move_msg,1248            is_loop_move,1249            has_suggest_reborrow,1250            maybe_reinitialized_locations_is_empty,1251        } = msg_opt;1252        let mut suggested_cloning = false;1253        if let UseSpans::FnSelfUse { var_span, fn_call_span, fn_span, kind } = move_spans {1254            let place_name = self1255                .describe_place(moved_place.as_ref())1256                .map(|n| format!("`{n}`"))1257                .unwrap_or_else(|| "value".to_owned());1258            match kind {1259                CallKind::FnCall { fn_trait_id, self_ty }1260                    if self.infcx.tcx.is_lang_item(fn_trait_id, LangItem::FnOnce) =>1261                {1262                    err.subdiagnostic(CaptureReasonLabel::Call {1263                        fn_call_span,1264                        place_name: &place_name,1265                        is_partial,1266                        is_loop_message,1267                    });1268                    // Check if the move occurs on a value because of a call on a closure that comes1269                    // from a type parameter `F: FnOnce()`. If so, we provide a targeted `note`:1270                    // ```1271                    // error[E0382]: use of moved value: `blk`1272                    //   --> $DIR/once-cant-call-twice-on-heap.rs:8:51273                    //    |1274                    // LL | fn foo<F:FnOnce()>(blk: F) {1275                    //    |                    --- move occurs because `blk` has type `F`, which does not implement the `Copy` trait1276                    // LL | blk();1277                    //    | ----- `blk` moved due to this call1278                    // LL | blk();1279                    //    | ^^^ value used here after move1280                    //    |1281                    // note: `FnOnce` closures can only be called once1282                    //   --> $DIR/once-cant-call-twice-on-heap.rs:6:101283                    //    |1284                    // LL | fn foo<F:FnOnce()>(blk: F) {1285                    //    |        ^^^^^^^^ `F` is made to be an `FnOnce` closure here1286                    // LL | blk();1287                    //    | ----- this value implements `FnOnce`, which causes it to be moved when called1288                    // ```1289                    if let ty::Param(param_ty) = *self_ty.kind()1290                        && let generics = self.infcx.tcx.generics_of(self.mir_def_id())1291                        && let param = generics.type_param(param_ty, self.infcx.tcx)1292                        && let Some(hir_generics) = self.infcx.tcx.hir_get_generics(1293                            self.infcx.tcx.typeck_root_def_id_local(self.mir_def_id()),1294                        )1295                        && let spans = hir_generics1296                            .predicates1297                            .iter()1298                            .filter_map(|pred| match pred.kind {1299                                hir::WherePredicateKind::BoundPredicate(pred) => Some(pred),1300                                _ => None,1301                            })1302                            .filter(|pred| {1303                                if let Some((id, _)) = pred.bounded_ty.as_generic_param() {1304                                    id == param.def_id1305                                } else {1306                                    false1307                                }1308                            })1309                            .flat_map(|pred| pred.bounds)1310                            .filter_map(|bound| {1311                                if let Some(trait_ref) = bound.trait_ref()1312                                    && let Some(trait_def_id) = trait_ref.trait_def_id()1313                                    && trait_def_id == fn_trait_id1314                                {1315                                    Some(bound.span())1316                                } else {1317                                    None1318                                }1319                            })1320                            .collect::<Vec<Span>>()1321                        && !spans.is_empty()1322                    {1323                        let mut span: MultiSpan = spans.clone().into();1324                        let msg = msg!("`{$ty}` is made to be an `FnOnce` closure here")1325                            .arg("ty", param_ty.to_string())1326                            .format();1327                        for sp in spans {1328                            span.push_span_label(sp, msg.clone());1329                        }1330                        span.push_span_label(1331                            fn_call_span,1332                            msg!("this value implements `FnOnce`, which causes it to be moved when called"),1333                        );1334                        err.span_note(span, msg!("`FnOnce` closures can only be called once"));1335                    } else {1336                        err.subdiagnostic(CaptureReasonNote::FnOnceMoveInCall { var_span });1337                    }1338                }1339                CallKind::Operator { self_arg, trait_id, .. } => {1340                    let self_arg = self_arg.unwrap();1341                    err.subdiagnostic(CaptureReasonLabel::OperatorUse {1342                        fn_call_span,1343                        place_name: &place_name,1344                        is_partial,1345                        is_loop_message,1346                    });1347                    if self.fn_self_span_reported.insert(fn_span) {1348                        let lang = self.infcx.tcx.lang_items();1349                        err.subdiagnostic(1350                            if [lang.not_trait(), lang.deref_trait(), lang.neg_trait()]1351                                .contains(&Some(trait_id))1352                            {1353                                CaptureReasonNote::UnOpMoveByOperator { span: self_arg.span }1354                            } else {1355                                CaptureReasonNote::LhsMoveByOperator { span: self_arg.span }1356                            },1357                        );1358                    }1359                }1360                CallKind::Normal { self_arg, desugaring, method_did, method_args } => {1361                    let self_arg = self_arg.unwrap();1362                    let mut has_sugg = false;1363                    let tcx = self.infcx.tcx;1364                    // Avoid pointing to the same function in multiple different1365                    // error messages.1366                    if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span) {1367                        self.explain_iterator_advancement_in_for_loop_if_applicable(1368                            err,1369                            span,1370                            &move_spans,1371                        );13721373                        let func = tcx.def_path_str(method_did);1374                        err.subdiagnostic(CaptureReasonNote::FuncTakeSelf {1375                            func,1376                            place_name: place_name.clone(),1377                            span: self_arg.span,1378                        });1379                    }1380                    let parent_did = tcx.parent(method_did);1381                    let parent_self_ty =1382                        matches!(tcx.def_kind(parent_did), rustc_hir::def::DefKind::Impl { .. })1383                            .then_some(parent_did)1384                            .and_then(|did| {1385                                match tcx.type_of(did).instantiate_identity().skip_norm_wip().kind()1386                                {1387                                    ty::Adt(def, ..) => Some(def.did()),1388                                    _ => None,1389                                }1390                            });1391                    let is_option_or_result = parent_self_ty.is_some_and(|def_id| {1392                        matches!(tcx.get_diagnostic_name(def_id), Some(sym::Option | sym::Result))1393                    });1394                    if is_option_or_result && maybe_reinitialized_locations_is_empty {1395                        err.subdiagnostic(CaptureReasonLabel::BorrowContent {1396                            var_span: var_span.shrink_to_hi(),1397                        });1398                    }1399                    if let Some((CallDesugaringKind::ForLoopIntoIter, _)) = desugaring {1400                        let ty = moved_place.ty(self.body, tcx).ty;1401                        let suggest = match tcx.get_diagnostic_item(sym::IntoIterator) {1402                            Some(def_id) => type_known_to_meet_bound_modulo_regions(1403                                self.infcx,1404                                self.infcx.param_env,1405                                Ty::new_imm_ref(tcx, tcx.lifetimes.re_erased, ty),1406                                def_id,1407                            ),1408                            _ => false,1409                        };1410                        if suggest {1411                            err.subdiagnostic(CaptureReasonSuggest::IterateSlice {1412                                ty,1413                                span: move_span.shrink_to_lo(),1414                            });1415                        }14161417                        err.subdiagnostic(CaptureReasonLabel::ImplicitCall {1418                            fn_call_span,1419                            place_name: &place_name,1420                            is_partial,1421                            is_loop_message,1422                        });1423                        // If the moved place was a `&mut` ref, then we can1424                        // suggest to reborrow it where it was moved, so it1425                        // will still be valid by the time we get to the usage.1426                        if let ty::Ref(_, _, hir::Mutability::Mut) =1427                            moved_place.ty(self.body, self.infcx.tcx).ty.kind()1428                        {1429                            // Suggest `reborrow` in other place for following situations:1430                            // 1. If we are in a loop this will be suggested later.1431                            // 2. If the moved value is a mut reference, it is used in a1432                            // generic function and the corresponding arg's type is generic param.1433                            if !is_loop_move && !has_suggest_reborrow {1434                                self.suggest_reborrow(1435                                    err,1436                                    move_span.shrink_to_lo(),1437                                    moved_place.as_ref(),1438                                );1439                            }1440                        }1441                    } else {1442                        if let Some((CallDesugaringKind::Await, _)) = desugaring {1443                            err.subdiagnostic(CaptureReasonLabel::Await {1444                                fn_call_span,1445                                place_name: &place_name,1446                                is_partial,1447                                is_loop_message,1448                            });1449                        } else {1450                            err.subdiagnostic(CaptureReasonLabel::MethodCall {1451                                fn_call_span,1452                                place_name: &place_name,1453                                is_partial,1454                                is_loop_message,1455                            });1456                        }1457                        // Erase and shadow everything that could be passed to the new infcx.1458                        let ty = moved_place.ty(self.body, tcx).ty;14591460                        if let ty::Adt(def, args) = ty.peel_refs().kind()1461                            && tcx.is_lang_item(def.did(), LangItem::Pin)1462                            && let ty::Ref(_, _, hir::Mutability::Mut) = args.type_at(0).kind()1463                            && let self_ty = self.infcx.instantiate_binder_with_fresh_vars(1464                                fn_call_span,1465                                BoundRegionConversionTime::FnCall,1466                                tcx.fn_sig(method_did)1467                                    .instantiate(tcx, method_args)1468                                    .skip_norm_wip()1469                                    .input(0),1470                            )1471                            && self.infcx.can_eq(self.infcx.param_env, ty, self_ty)1472                        {1473                            err.subdiagnostic(CaptureReasonSuggest::FreshReborrow {1474                                span: move_span.shrink_to_hi(),1475                            });1476                            has_sugg = true;1477                        }1478                        if let Some(clone_trait) = tcx.lang_items().clone_trait() {1479                            // Check whether the deref is from a custom Deref impl1480                            // (e.g. Rc, Box) or a built-in reference deref.1481                            // For built-in derefs with Clone fully satisfied, we skip1482                            // the UFCS suggestion here and let `suggest_cloning`1483                            // downstream emit a simpler `.clone()` suggestion instead.1484                            let has_overloaded_deref =1485                                moved_place.iter_projections().any(|(place, elem)| {1486                                    matches!(elem, ProjectionElem::Deref)1487                                        && matches!(1488                                            self.borrowed_content_source(place),1489                                            BorrowedContentSource::OverloadedDeref(_)1490                                                | BorrowedContentSource::OverloadedIndex(_)1491                                        )1492                                });14931494                            let has_deref = moved_place1495                                .iter_projections()1496                                .any(|(_, elem)| matches!(elem, ProjectionElem::Deref));14971498                            let sugg = if has_deref {1499                                let (start, end) = if let Some(expr) = self.find_expr(move_span)1500                                    && let Some(_) = self.clone_on_reference(expr)1501                                    && let hir::ExprKind::MethodCall(_, rcvr, _, _) = expr.kind1502                                {1503                                    (move_span.shrink_to_lo(), move_span.with_lo(rcvr.span.hi()))1504                                } else {1505                                    (move_span.shrink_to_lo(), move_span.shrink_to_hi())1506                                };1507                                vec![1508                                    // We use the fully-qualified path because `.clone()` can1509                                    // sometimes choose `<&T as Clone>` instead of `<T as Clone>`1510                                    // when going through auto-deref, so this ensures that doesn't1511                                    // happen, causing suggestions for `.clone().clone()`.1512                                    (start, format!("<{ty} as Clone>::clone(&")),1513                                    (end, ")".to_string()),1514                                ]1515                            } else {1516                                vec![(move_span.shrink_to_hi(), ".clone()".to_string())]1517                            };1518                            if let Some(errors) = self.infcx.type_implements_trait_shallow(1519                                clone_trait,1520                                ty,1521                                self.infcx.param_env,1522                            ) && !has_sugg1523                            {1524                                let skip_for_simple_clone =1525                                    has_deref && !has_overloaded_deref && errors.is_empty();1526                                if !skip_for_simple_clone {1527                                    let msg = match &errors[..] {1528                                        [] => "you can `clone` the value and consume it, but \1529                                               this might not be your desired behavior"1530                                            .to_string(),1531                                        [error] => {1532                                            format!(1533                                                "you could `clone` the value and consume it, if \1534                                                 the `{}` trait bound could be satisfied",1535                                                error.obligation.predicate,1536                                            )1537                                        }1538                                        _ => {1539                                            format!(1540                                                "you could `clone` the value and consume it, if \1541                                                 the following trait bounds could be satisfied: \1542                                                 {}",1543                                                listify(1544                                                    &errors,1545                                                    |e: &FulfillmentError<'tcx>| format!(1546                                                        "`{}`",1547                                                        e.obligation.predicate1548                                                    )1549                                                )1550                                                .unwrap(),1551                                            )1552                                        }1553                                    };1554                                    err.multipart_suggestion(1555                                        msg,1556                                        sugg,1557                                        Applicability::MaybeIncorrect,1558                                    );15591560                                    suggested_cloning = errors.is_empty();15611562                                    for error in errors {1563                                        if let FulfillmentErrorCode::Select(1564                                            SelectionError::Unimplemented,1565                                        ) = error.code1566                                            && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(1567                                                pred,1568                                            )) = error.obligation.predicate.kind().skip_binder()1569                                        {1570                                            self.infcx.err_ctxt().suggest_derive(1571                                                &error.obligation,1572                                                err,1573                                                error.obligation.predicate.kind().rebind(pred),1574                                            );1575                                        }1576                                    }1577                                }1578                            }1579                        }1580                    }1581                }1582                // Other desugarings takes &self, which cannot cause a move1583                _ => {}1584            }1585        } else {1586            if move_span != span || is_loop_message {1587                err.subdiagnostic(CaptureReasonLabel::MovedHere {1588                    move_span,1589                    is_partial,1590                    is_move_msg,1591                    is_loop_message,1592                });1593            }1594            // If the move error occurs due to a loop, don't show1595            // another message for the same span1596            if !is_loop_message {1597                move_spans.var_subdiag(err, None, |kind, var_span| match kind {1598                    hir::ClosureKind::Coroutine(_) => {1599                        CaptureVarCause::PartialMoveUseInCoroutine { var_span, is_partial }1600                    }1601                    hir::ClosureKind::Closure | hir::ClosureKind::CoroutineClosure(_) => {1602                        CaptureVarCause::PartialMoveUseInClosure { var_span, is_partial }1603                    }1604                })1605            }1606        }1607        if suggested_cloning { CloneSuggestion::Emitted } else { CloneSuggestion::NotEmitted }1608    }16091610    /// Skip over locals that begin with an underscore or have no name1611    pub(crate) fn local_excluded_from_unused_mut_lint(&self, index: Local) -> bool {1612        self.local_name(index).is_none_or(|name| name.as_str().starts_with('_'))1613    }1614}16151616const LIMITATION_NOTE: DiagMessage =1617    msg!("due to a current limitation of the type system, this implies a `'static` lifetime");