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::LocalMutationIsAllowed;38use crate::constraints::OutlivesConstraint;39use crate::nll::ConstraintDescription;40use crate::session_diagnostics::{41    CaptureArgLabel, CaptureReasonLabel, CaptureReasonNote, CaptureReasonSuggest, CaptureVarCause,42    CaptureVarKind, CaptureVarPathUseCause, OnClosureNote,43};4445mod find_all_local_uses;46mod find_use;47mod outlives_suggestion;48mod region_name;49mod var_name;5051mod bound_region_errors;52mod conflict_errors;53mod explain_borrow;54mod move_errors;55mod mutability_errors;56mod opaque_types;57mod region_errors;5859pub(crate) use bound_region_errors::{ToUniverseInfo, UniverseInfo};60pub(crate) use move_errors::{IllegalMoveOriginKind, MoveError};61pub(crate) use mutability_errors::AccessKind;62pub(crate) use outlives_suggestion::OutlivesSuggestionBuilder;63pub(crate) use region_errors::{ErrorConstraintInfo, RegionErrorKind, RegionErrors};64pub(crate) use region_name::{RegionName, RegionNameSource};65pub(crate) use rustc_trait_selection::error_reporting::traits::call_kind::CallKind;6667pub(super) struct DescribePlaceOpt {68    including_downcast: bool,6970    /// Enable/Disable tuple fields.71    /// For example `x` tuple. if it's `true` `x.0`. Otherwise `x`72    including_tuple_field: bool,73}7475pub(super) struct IncludingTupleField(pub(super) bool);7677enum BufferedDiag<'infcx> {78    Error(Diag<'infcx>),79    NonError(Diag<'infcx, ()>),80}8182impl<'infcx> BufferedDiag<'infcx> {83    fn sort_span(&self) -> Span {84        match self {85            BufferedDiag::Error(diag) => diag.sort_span,86            BufferedDiag::NonError(diag) => diag.sort_span,87        }88    }89}9091#[derive(Default)]92pub(crate) struct BorrowckDiagnosticsBuffer<'infcx, 'tcx> {93    /// This field keeps track of move errors that are to be reported for given move indices.94    ///95    /// There are situations where many errors can be reported for a single move out (see96    /// #53807) and we want only the best of those errors.97    ///98    /// The `report_use_of_moved_or_uninitialized` function checks this map and replaces the99    /// diagnostic (if there is one) if the `Place` of the error being reported is a prefix of100    /// the `Place` of the previous most diagnostic. This happens instead of buffering the101    /// error. Once all move errors have been reported, any diagnostics in this map are added102    /// to the buffer to be emitted.103    ///104    /// `BTreeMap` is used to preserve the order of insertions when iterating. This is necessary105    /// when errors in the map are being re-added to the error buffer so that errors with the106    /// same primary span come out in a consistent order.107    buffered_move_errors: BTreeMap<Vec<MoveOutIndex>, (PlaceRef<'tcx>, Diag<'infcx>)>,108109    buffered_mut_errors: FxIndexMap<Span, (Diag<'infcx>, usize)>,110111    /// Buffer of diagnostics to be reported. A mixture of error and non-error diagnostics.112    buffered_diags: Vec<BufferedDiag<'infcx>>,113}114115impl<'infcx, 'tcx> BorrowckDiagnosticsBuffer<'infcx, 'tcx> {116    pub(crate) fn buffer_non_error(&mut self, diag: Diag<'infcx, ()>) {117        self.buffered_diags.push(BufferedDiag::NonError(diag));118    }119}120121impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {122    pub(crate) fn buffer_error(&mut self, diag: Diag<'infcx>) {123        self.diags_buffer.buffered_diags.push(BufferedDiag::Error(diag));124    }125126    pub(crate) fn buffer_non_error(&mut self, diag: Diag<'infcx, ()>) {127        self.diags_buffer.buffer_non_error(diag);128    }129130    pub(crate) fn buffer_move_error(131        &mut self,132        move_out_indices: Vec<MoveOutIndex>,133        place_and_err: (PlaceRef<'tcx>, Diag<'infcx>),134    ) -> bool {135        if let Some((_, diag)) =136            self.diags_buffer.buffered_move_errors.insert(move_out_indices, place_and_err)137        {138            // Cancel the old diagnostic so we don't ICE139            diag.cancel();140            false141        } else {142            true143        }144    }145146    pub(crate) fn get_buffered_mut_error(&mut self, span: Span) -> Option<(Diag<'infcx>, usize)> {147        // FIXME(#120456) - is `swap_remove` correct?148        self.diags_buffer.buffered_mut_errors.swap_remove(&span)149    }150151    pub(crate) fn buffer_mut_error(&mut self, span: Span, diag: Diag<'infcx>, count: usize) {152        self.diags_buffer.buffered_mut_errors.insert(span, (diag, count));153    }154155    pub(crate) fn emit_errors(&mut self) -> Option<ErrorGuaranteed> {156        let mut res = self.infcx.tainted_by_errors();157158        // Buffer any move errors that we collected and de-duplicated.159        for (_, (_, diag)) in std::mem::take(&mut self.diags_buffer.buffered_move_errors) {160            // We have already set tainted for this error, so just buffer it.161            self.buffer_error(diag);162        }163        for (_, (mut diag, count)) in std::mem::take(&mut self.diags_buffer.buffered_mut_errors) {164            if count > 10 {165                diag.note(format!("...and {} other attempted mutable borrows", count - 10));166            }167            self.buffer_error(diag);168        }169170        if !self.diags_buffer.buffered_diags.is_empty() {171            self.diags_buffer.buffered_diags.sort_by_key(|buffered_diag| buffered_diag.sort_span());172            for buffered_diag in self.diags_buffer.buffered_diags.drain(..) {173                match buffered_diag {174                    BufferedDiag::Error(diag) => res = Some(diag.emit()),175                    BufferedDiag::NonError(diag) => diag.emit(),176                }177            }178        }179180        res181    }182183    pub(crate) fn has_buffered_diags(&self) -> bool {184        self.diags_buffer.buffered_diags.is_empty()185    }186187    pub(crate) fn has_move_error(188        &self,189        move_out_indices: &[MoveOutIndex],190    ) -> Option<&(PlaceRef<'tcx>, Diag<'infcx>)> {191        self.diags_buffer.buffered_move_errors.get(move_out_indices)192    }193194    /// Uses `body.var_debug_info` to find the symbol195    fn local_name(&self, index: Local) -> Option<Symbol> {196        *self.local_names().get(index)?197    }198199    fn local_names(&self) -> &IndexSlice<Local, Option<Symbol>> {200        self.local_names.get_or_init(|| {201            let mut local_names = IndexVec::from_elem(None, &self.body.local_decls);202            for var_debug_info in &self.body.var_debug_info {203                if let VarDebugInfoContents::Place(place) = var_debug_info.value {204                    if let Some(local) = place.as_local() {205                        if let Some(prev_name) = local_names[local]206                            && var_debug_info.name != prev_name207                        {208                            span_bug!(209                                var_debug_info.source_info.span,210                                "local {:?} has many names (`{}` vs `{}`)",211                                local,212                                prev_name,213                                var_debug_info.name214                            );215                        }216                        local_names[local] = Some(var_debug_info.name);217                    }218                }219            }220            local_names221        })222    }223}224225impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {226    /// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure227    /// is moved after being invoked.228    ///229    /// ```text230    /// note: closure cannot be invoked more than once because it moves the variable `dict` out of231    ///       its environment232    ///   --> $DIR/issue-42065.rs:16:29233    ///    |234    /// LL |         for (key, value) in dict {235    ///    |                             ^^^^236    /// ```237    pub(super) fn add_moved_or_invoked_closure_note(238        &self,239        location: Location,240        place: PlaceRef<'tcx>,241        diag: &mut Diag<'infcx>,242    ) -> bool {243        debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place);244        let mut target = place.local_or_deref_local();245        for stmt in &self.body[location.block].statements[location.statement_index..] {246            debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target);247            if let StatementKind::Assign((into, Rvalue::Use(from, _))) = &stmt.kind {248                debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from);249                match from {250                    Operand::Copy(place) | Operand::Move(place)251                        if target == place.local_or_deref_local() =>252                    {253                        target = into.local_or_deref_local()254                    }255                    _ => {}256                }257            }258        }259260        // Check if we are attempting to call a closure after it has been invoked.261        let terminator = self.body[location.block].terminator();262        debug!("add_moved_or_invoked_closure_note: terminator={:?}", terminator);263        if let TerminatorKind::Call {264            func: Operand::Constant(ConstOperand { const_, .. }),265            args,266            ..267        } = &terminator.kind268            && let ty::FnDef(id, _) = *const_.ty().kind()269        {270            debug!("add_moved_or_invoked_closure_note: id={:?}", id);271            if self.infcx.tcx.is_lang_item(self.infcx.tcx.parent(id), LangItem::FnOnce) {272                let closure = match args.first() {273                    Some(Spanned { node: Operand::Copy(place) | Operand::Move(place), .. })274                        if target == place.local_or_deref_local() =>275                    {276                        place.local_or_deref_local().unwrap()277                    }278                    _ => return false,279                };280281                debug!("add_moved_or_invoked_closure_note: closure={:?}", closure);282                if let ty::Closure(did, _) = self.body.local_decls[closure].ty.kind() {283                    let did = did.expect_local();284                    if let Some((span, hir_place)) = self.infcx.tcx.closure_kind_origin(did) {285                        diag.subdiagnostic(OnClosureNote::InvokedTwice {286                            place_name: &ty::place_to_string_for_capture(self.infcx.tcx, hir_place),287                            span: *span,288                        });289                        return true;290                    }291                }292            }293        }294295        // Check if we are just moving a closure after it has been invoked.296        if let Some(target) = target297            && let ty::Closure(did, _) = self.body.local_decls[target].ty.kind()298        {299            let did = did.expect_local();300            if let Some((span, hir_place)) = self.infcx.tcx.closure_kind_origin(did) {301                diag.subdiagnostic(OnClosureNote::MovedTwice {302                    place_name: &ty::place_to_string_for_capture(self.infcx.tcx, hir_place),303                    span: *span,304                });305                return true;306            }307        }308        false309    }310311    /// End-user visible description of `place` if one can be found.312    /// If the place is a temporary for instance, `"value"` will be returned.313    pub(super) fn describe_any_place(&self, place_ref: PlaceRef<'tcx>) -> String {314        match self.describe_place(place_ref) {315            Some(mut descr) => {316                // Surround descr with `backticks`.317                descr.reserve(2);318                descr.insert(0, '`');319                descr.push('`');320                descr321            }322            None => "value".to_string(),323        }324    }325326    /// End-user visible description of `place` if one can be found.327    /// If the place is a temporary for instance, `None` will be returned.328    pub(super) fn describe_place(&self, place_ref: PlaceRef<'tcx>) -> Option<String> {329        self.describe_place_with_options(330            place_ref,331            DescribePlaceOpt { including_downcast: false, including_tuple_field: true },332        )333    }334335    /// End-user visible description of `place` if one can be found. If the place is a temporary336    /// for instance, `None` will be returned.337    /// `IncludingDowncast` parameter makes the function return `None` if `ProjectionElem` is338    /// `Downcast` and `IncludingDowncast` is true339    pub(super) fn describe_place_with_options(340        &self,341        place: PlaceRef<'tcx>,342        opt: DescribePlaceOpt,343    ) -> Option<String> {344        let local = place.local;345        if self.body.local_decls[local]346            .source_info347            .span348            .in_external_macro(self.infcx.tcx.sess.source_map())349        {350            return None;351        }352353        let mut autoderef_index = None;354        let mut buf = String::new();355        let mut ok = self.append_local_to_string(local, &mut buf);356357        for (index, elem) in place.projection.into_iter().enumerate() {358            match elem {359                ProjectionElem::Deref => {360                    if index == 0 {361                        if self.body.local_decls[local].is_ref_for_guard() {362                            continue;363                        }364                        if let LocalInfo::StaticRef { def_id, .. } =365                            *self.body.local_decls[local].local_info()366                        {367                            buf.push_str(self.infcx.tcx.item_name(def_id).as_str());368                            ok = Ok(());369                            continue;370                        }371                    }372                    if let Some(field) = self.is_upvar_field_projection(PlaceRef {373                        local,374                        projection: place.projection.split_at(index + 1).0,375                    }) {376                        let var_index = field.index();377                        buf = self.upvars[var_index].to_string(self.infcx.tcx);378                        ok = Ok(());379                        if !self.upvars[var_index].is_by_ref() {380                            buf.insert(0, '*');381                        }382                    } else {383                        if autoderef_index.is_none() {384                            autoderef_index = match place.projection.iter().rposition(|elem| {385                                !matches!(386                                    elem,387                                    ProjectionElem::Deref | ProjectionElem::Downcast(..)388                                )389                            }) {390                                Some(index) => Some(index + 1),391                                None => Some(0),392                            };393                        }394                        if index >= autoderef_index.unwrap() {395                            buf.insert(0, '*');396                        }397                    }398                }399                ProjectionElem::Downcast(..) if opt.including_downcast => return None,400                ProjectionElem::Downcast(..) => (),401                ProjectionElem::OpaqueCast(..) => (),402                ProjectionElem::UnwrapUnsafeBinder(_) => (),403                ProjectionElem::Field(field, _ty) => {404                    // FIXME(project-rfc_2229#36): print capture precisely here.405                    if let Some(field) = self.is_upvar_field_projection(PlaceRef {406                        local,407                        projection: place.projection.split_at(index + 1).0,408                    }) {409                        buf = self.upvars[field.index()].to_string(self.infcx.tcx);410                        ok = Ok(());411                    } else {412                        let field_name = self.describe_field(413                            PlaceRef { local, projection: place.projection.split_at(index).0 },414                            *field,415                            IncludingTupleField(opt.including_tuple_field),416                        );417                        if let Some(field_name_str) = field_name {418                            buf.push('.');419                            buf.push_str(&field_name_str);420                        }421                    }422                }423                ProjectionElem::Index(index) => {424                    buf.push('[');425                    if self.append_local_to_string(*index, &mut buf).is_err() {426                        buf.push('_');427                    }428                    buf.push(']');429                }430                ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {431                    // Since it isn't possible to borrow an element on a particular index and432                    // then use another while the borrow is held, don't output indices details433                    // to avoid confusing the end-user434                    buf.push_str("[..]");435                }436            }437        }438        ok.ok().map(|_| buf)439    }440441    fn describe_name(&self, place: PlaceRef<'tcx>) -> Option<Symbol> {442        for elem in place.projection.into_iter() {443            match elem {444                ProjectionElem::Downcast(Some(name), _) => {445                    return Some(*name);446                }447                _ => {}448            }449        }450        None451    }452453    /// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have454    /// a name, or its name was generated by the compiler, then `Err` is returned455    fn append_local_to_string(&self, local: Local, buf: &mut String) -> Result<(), ()> {456        let decl = &self.body.local_decls[local];457        match self.local_name(local) {458            Some(name) if !decl.from_compiler_desugaring() => {459                buf.push_str(name.as_str());460                Ok(())461            }462            _ => Err(()),463        }464    }465466    /// End-user visible description of the `field`nth field of `base`467    fn describe_field(468        &self,469        place: PlaceRef<'tcx>,470        field: FieldIdx,471        including_tuple_field: IncludingTupleField,472    ) -> Option<String> {473        let place_ty = match place {474            PlaceRef { local, projection: [] } => PlaceTy::from_ty(self.body.local_decls[local].ty),475            PlaceRef { local, projection: [proj_base @ .., elem] } => match elem {476                ProjectionElem::Deref477                | ProjectionElem::Index(..)478                | ProjectionElem::ConstantIndex { .. }479                | ProjectionElem::Subslice { .. } => {480                    PlaceRef { local, projection: proj_base }.ty(self.body, self.infcx.tcx)481                }482                ProjectionElem::Downcast(..) => place.ty(self.body, self.infcx.tcx),483                ProjectionElem::OpaqueCast(ty) | ProjectionElem::UnwrapUnsafeBinder(ty) => {484                    PlaceTy::from_ty(*ty)485                }486                ProjectionElem::Field(_, field_type) => PlaceTy::from_ty(*field_type),487            },488        };489        self.describe_field_from_ty(490            place_ty.ty,491            field,492            place_ty.variant_index,493            including_tuple_field,494        )495    }496497    /// End-user visible description of the `field_index`nth field of `ty`498    fn describe_field_from_ty(499        &self,500        ty: Ty<'_>,501        field: FieldIdx,502        variant_index: Option<VariantIdx>,503        including_tuple_field: IncludingTupleField,504    ) -> Option<String> {505        if let Some(boxed_ty) = ty.boxed_ty() {506            // If the type is a box, the field is described from the boxed type507            self.describe_field_from_ty(boxed_ty, field, variant_index, including_tuple_field)508        } else {509            match *ty.kind() {510                ty::Adt(def, _) => {511                    let variant = if let Some(idx) = variant_index {512                        assert!(def.is_enum());513                        def.variant(idx)514                    } else {515                        def.non_enum_variant()516                    };517                    if !including_tuple_field.0 && variant.ctor_kind() == Some(CtorKind::Fn) {518                        return None;519                    }520                    Some(variant.fields[field].name.to_string())521                }522                ty::Tuple(_) => Some(field.index().to_string()),523                ty::Ref(_, ty, _) | ty::RawPtr(ty, _) => {524                    self.describe_field_from_ty(ty, field, variant_index, including_tuple_field)525                }526                ty::Array(ty, _) | ty::Slice(ty) => {527                    self.describe_field_from_ty(ty, field, variant_index, including_tuple_field)528                }529                ty::Closure(def_id, _) | ty::Coroutine(def_id, _) => {530                    // We won't be borrowck'ing here if the closure came from another crate,531                    // so it's safe to call `expect_local`.532                    //533                    // We know the field exists so it's safe to call operator[] and `unwrap` here.534                    let def_id = def_id.expect_local();535                    let var_id =536                        self.infcx.tcx.closure_captures(def_id)[field.index()].get_root_variable();537538                    Some(self.infcx.tcx.hir_name(var_id).to_string())539                }540                _ => {541                    // This can happen for field accesses on `Box<T>`: the field is542                    // described from the boxed type, which may have no named fields543                    Some(field.index().to_string())544                }545            }546        }547    }548549    pub(super) fn borrowed_content_source(550        &self,551        deref_base: PlaceRef<'tcx>,552    ) -> BorrowedContentSource<'tcx> {553        let tcx = self.infcx.tcx;554555        // Look up the provided place and work out the move path index for it,556        // we'll use this to check whether it was originally from an overloaded557        // operator.558        match self.move_data.rev_lookup.find(deref_base) {559            LookupResult::Exact(mpi) | LookupResult::Parent(Some(mpi)) => {560                debug!("borrowed_content_source: mpi={:?}", mpi);561562                for i in &self.move_data.init_path_map[mpi] {563                    let init = &self.move_data.inits[*i];564                    debug!("borrowed_content_source: init={:?}", init);565                    // We're only interested in statements that initialized a value, not the566                    // initializations from arguments.567                    let InitLocation::Statement(loc) = init.location else { continue };568569                    let bbd = &self.body[loc.block];570                    let is_terminator = bbd.statements.len() == loc.statement_index;571                    debug!(572                        "borrowed_content_source: loc={:?} is_terminator={:?}",573                        loc, is_terminator,574                    );575                    if !is_terminator {576                        continue;577                    } else if let Some(Terminator {578                        kind:579                            TerminatorKind::Call {580                                func,581                                call_source: CallSource::OverloadedOperator,582                                ..583                            },584                        ..585                    }) = &bbd.terminator586                    {587                        if let Some(source) =588                            BorrowedContentSource::from_call(func.ty(self.body, tcx), tcx)589                        {590                            return source;591                        }592                    }593                }594            }595            // Base is a `static` so won't be from an overloaded operator596            _ => (),597        };598599        // If we didn't find an overloaded deref or index, then assume it's a600        // built in deref and check the type of the base.601        let base_ty = deref_base.ty(self.body, tcx).ty;602        if base_ty.is_raw_ptr() {603            BorrowedContentSource::DerefRawPointer604        } else if base_ty.is_mutable_ptr() {605            BorrowedContentSource::DerefMutableRef606        } else if base_ty.is_ref() {607            BorrowedContentSource::DerefSharedRef608        } else {609            // Custom type implementing `Deref` (e.g. `MyBox<T>`, `Rc<T>`, `Arc<T>`)610            // that wasn't detected via the MIR init trace above. This can happen611            // when the deref base is initialized by a regular statement rather than612            // a `TerminatorKind::Call` with `CallSource::OverloadedOperator`.613            BorrowedContentSource::OverloadedDeref(base_ty)614        }615    }616617    /// Return the name of the provided `Ty` (that must be a reference) with a synthesized lifetime618    /// name where required.619    pub(super) fn get_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {620        let mut p = ty::print::FmtPrinter::new(self.infcx.tcx, Namespace::TypeNS);621622        // We need to add synthesized lifetimes where appropriate. We do623        // this by hooking into the pretty printer and telling it to label the624        // lifetimes without names with the value `'0`.625        if let ty::Ref(region, ..) = ty.kind() {626            match region.kind() {627                ty::ReBound(_, ty::BoundRegion { kind: br, .. })628                | ty::RePlaceholder(ty::PlaceholderRegion {629                    bound: ty::BoundRegion { kind: br, .. },630                    ..631                }) => p.region_highlight_mode.highlighting_bound_region(br, counter),632                _ => {}633            }634        }635636        ty.print(&mut p).unwrap();637        p.into_buffer()638    }639640    /// Returns the name of the provided `Ty` (that must be a reference)'s region with a641    /// synthesized lifetime name where required.642    pub(super) fn get_region_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String {643        let mut p = ty::print::FmtPrinter::new(self.infcx.tcx, Namespace::TypeNS);644645        let region = if let ty::Ref(region, ..) = ty.kind() {646            match region.kind() {647                ty::ReBound(_, ty::BoundRegion { kind: br, .. })648                | ty::RePlaceholder(ty::PlaceholderRegion {649                    bound: ty::BoundRegion { kind: br, .. },650                    ..651                }) => p.region_highlight_mode.highlighting_bound_region(br, counter),652                _ => {}653            }654            region655        } else {656            bug!("ty for annotation of borrow region is not a reference");657        };658659        region.print(&mut p).unwrap();660        p.into_buffer()661    }662663    /// Add a note to region errors and borrow explanations when higher-ranked regions in predicates664    /// implicitly introduce an "outlives `'static`" constraint.665    ///666    /// This is very similar to `fn suggest_static_lifetime_for_gat_from_hrtb` which handles this667    /// note for failed type tests instead of outlives errors.668    fn add_placeholder_from_predicate_note<G: EmissionGuarantee>(669        &self,670        diag: &mut Diag<'_, G>,671        path: &[OutlivesConstraint<'tcx>],672    ) {673        let tcx = self.infcx.tcx;674        let Some((gat_hir_id, generics)) = path.iter().find_map(|constraint| {675            let outlived = constraint.sub;676            if let Some(origin) = self.regioncx.definitions.get(outlived)677                && let NllRegionVariableOrigin::Placeholder(placeholder) = origin.origin678                && let Some(id) = placeholder.bound.kind.get_id()679                && let Some(placeholder_id) = id.as_local()680                && let gat_hir_id = tcx.local_def_id_to_hir_id(placeholder_id)681                && let Some(generics_impl) =682                    tcx.parent_hir_node(tcx.parent_hir_id(gat_hir_id)).generics()683            {684                Some((gat_hir_id, generics_impl))685            } else {686                None687            }688        }) else {689            return;690        };691692        // Look for the where-bound which introduces the placeholder.693        // As we're using the HIR, we need to handle both `for<'a> T: Trait<'a>`694        // and `T: for<'a> Trait`<'a>.695        for pred in generics.predicates {696            let WherePredicateKind::BoundPredicate(WhereBoundPredicate {697                bound_generic_params,698                bounds,699                ..700            }) = pred.kind701            else {702                continue;703            };704            if bound_generic_params705                .iter()706                .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == gat_hir_id)707                .is_some()708            {709                diag.span_note(pred.span, LIMITATION_NOTE);710                return;711            }712            for bound in bounds.iter() {713                if let GenericBound::Trait(bound) = bound {714                    if bound715                        .bound_generic_params716                        .iter()717                        .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == gat_hir_id)718                        .is_some()719                    {720                        diag.span_note(bound.span, LIMITATION_NOTE);721                        return;722                    }723                }724            }725        }726    }727728    /// Add a label to region errors and borrow explanations when outlives constraints arise from729    /// proving a type implements `Sized` or `Copy`.730    fn add_sized_or_copy_bound_info<G: EmissionGuarantee>(731        &self,732        err: &mut Diag<'_, G>,733        blamed_category: ConstraintCategory<'tcx>,734        path: &[OutlivesConstraint<'tcx>],735    ) {736        for sought_category in [ConstraintCategory::SizedBound, ConstraintCategory::CopyBound] {737            if sought_category != blamed_category738                && let Some(sought_constraint) = path.iter().find(|c| c.category == sought_category)739            {740                let label = format!(741                    "requirement occurs due to {}",742                    sought_category.description().trim_end()743                );744                err.span_label(sought_constraint.span, label);745            }746        }747    }748}749750/// The span(s) associated to a use of a place.751#[derive(Copy, Clone, PartialEq, Eq, Debug)]752pub(super) enum UseSpans<'tcx> {753    /// The access is caused by capturing a variable for a closure.754    ClosureUse {755        /// This is true if the captured variable was from a coroutine.756        closure_kind: hir::ClosureKind,757        /// The span of the args of the closure, including the `move` keyword if758        /// it's present.759        args_span: Span,760        /// The span of the use resulting in capture kind761        /// Check `ty::CaptureInfo` for more details762        capture_kind_span: Span,763        /// The span of the use resulting in the captured path764        /// Check `ty::CaptureInfo` for more details765        path_span: Span,766    },767    /// The access is caused by using a variable as the receiver of a method768    /// that takes 'self'769    FnSelfUse {770        /// The span of the variable being moved771        var_span: Span,772        /// The span of the method call on the variable773        fn_call_span: Span,774        /// The definition span of the method being called775        fn_span: Span,776        kind: CallKind<'tcx>,777    },778    /// This access is caused by a `match` or `if let` pattern.779    PatUse(Span),780    /// This access has a single span associated to it: common case.781    OtherUse(Span),782}783784impl UseSpans<'_> {785    pub(super) fn args_or_use(self) -> Span {786        match self {787            UseSpans::ClosureUse { args_span: span, .. }788            | UseSpans::PatUse(span)789            | UseSpans::OtherUse(span) => span,790            UseSpans::FnSelfUse { var_span, .. } => var_span,791        }792    }793794    /// Returns the span of `self`, in the case of a `ClosureUse` returns the `path_span`795    pub(super) fn var_or_use_path_span(self) -> Span {796        match self {797            UseSpans::ClosureUse { path_span: span, .. }798            | UseSpans::PatUse(span)799            | UseSpans::OtherUse(span) => span,800            UseSpans::FnSelfUse { var_span, .. } => var_span,801        }802    }803804    /// Returns the span of `self`, in the case of a `ClosureUse` returns the `capture_kind_span`805    pub(super) fn var_or_use(self) -> Span {806        match self {807            UseSpans::ClosureUse { capture_kind_span: span, .. }808            | UseSpans::PatUse(span)809            | UseSpans::OtherUse(span) => span,810            UseSpans::FnSelfUse { var_span, .. } => var_span,811        }812    }813814    // FIXME(coroutines): Make this just return the `ClosureKind` directly?815    pub(super) fn coroutine_kind(self) -> Option<CoroutineKind> {816        match self {817            UseSpans::ClosureUse {818                closure_kind: hir::ClosureKind::Coroutine(coroutine_kind),819                ..820            } => Some(coroutine_kind),821            _ => None,822        }823    }824825    /// Add a span label to the arguments of the closure, if it exists.826    pub(super) fn args_subdiag(self, err: &mut Diag<'_>, f: impl FnOnce(Span) -> CaptureArgLabel) {827        if let UseSpans::ClosureUse { args_span, .. } = self {828            err.subdiagnostic(f(args_span));829        }830    }831832    /// Add a span label to the use of the captured variable, if it exists.833    /// only adds label to the `path_span`834    pub(super) fn var_path_only_subdiag(835        self,836        err: &mut Diag<'_>,837        action: crate::InitializationRequiringAction,838    ) {839        use CaptureVarPathUseCause::*;840841        use crate::InitializationRequiringAction::*;842        if let UseSpans::ClosureUse { closure_kind, path_span, .. } = self {843            match closure_kind {844                hir::ClosureKind::Coroutine(_) => {845                    err.subdiagnostic(match action {846                        Borrow => BorrowInCoroutine { path_span },847                        MatchOn | Use => UseInCoroutine { path_span },848                        Assignment => AssignInCoroutine { path_span },849                        PartialAssignment => AssignPartInCoroutine { path_span },850                    });851                }852                hir::ClosureKind::Closure | hir::ClosureKind::CoroutineClosure(_) => {853                    err.subdiagnostic(match action {854                        Borrow => BorrowInClosure { path_span },855                        MatchOn | Use => UseInClosure { path_span },856                        Assignment => AssignInClosure { path_span },857                        PartialAssignment => AssignPartInClosure { path_span },858                    });859                }860            }861        }862    }863864    /// Add a subdiagnostic to the use of the captured variable, if it exists.865    pub(super) fn var_subdiag(866        self,867        err: &mut Diag<'_>,868        kind: Option<rustc_middle::mir::BorrowKind>,869        f: impl FnOnce(hir::ClosureKind, Span) -> CaptureVarCause,870    ) {871        if let UseSpans::ClosureUse { closure_kind, capture_kind_span, path_span, .. } = self {872            if capture_kind_span != path_span {873                err.subdiagnostic(match kind {874                    Some(kd) => match kd {875                        rustc_middle::mir::BorrowKind::Shared876                        | rustc_middle::mir::BorrowKind::Fake(_) => {877                            CaptureVarKind::Immut { kind_span: capture_kind_span }878                        }879880                        rustc_middle::mir::BorrowKind::Mut { .. } => {881                            CaptureVarKind::Mut { kind_span: capture_kind_span }882                        }883                    },884                    None => CaptureVarKind::Move { kind_span: capture_kind_span },885                });886            };887            let diag = f(closure_kind, path_span);888            err.subdiagnostic(diag);889        }890    }891892    /// Returns `false` if this place is not used in a closure.893    pub(super) fn for_closure(&self) -> bool {894        match *self {895            UseSpans::ClosureUse { closure_kind, .. } => {896                matches!(closure_kind, hir::ClosureKind::Closure)897            }898            _ => false,899        }900    }901902    /// Returns `false` if this place is not used in a coroutine.903    pub(super) fn for_coroutine(&self) -> bool {904        match *self {905            // FIXME(coroutines): Do we want this to apply to synthetic coroutines?906            UseSpans::ClosureUse { closure_kind, .. } => {907                matches!(closure_kind, hir::ClosureKind::Coroutine(..))908            }909            _ => false,910        }911    }912913    pub(super) fn or_else<F>(self, if_other: F) -> Self914    where915        F: FnOnce() -> Self,916    {917        match self {918            closure @ UseSpans::ClosureUse { .. } => closure,919            UseSpans::PatUse(_) | UseSpans::OtherUse(_) => if_other(),920            fn_self @ UseSpans::FnSelfUse { .. } => fn_self,921        }922    }923}924925pub(super) enum BorrowedContentSource<'tcx> {926    DerefRawPointer,927    DerefMutableRef,928    DerefSharedRef,929    OverloadedDeref(Ty<'tcx>),930    OverloadedIndex(Ty<'tcx>),931}932933impl<'tcx> BorrowedContentSource<'tcx> {934    pub(super) fn describe_for_unnamed_place(&self, tcx: TyCtxt<'_>) -> String {935        match *self {936            BorrowedContentSource::DerefRawPointer => "a raw pointer".to_string(),937            BorrowedContentSource::DerefSharedRef => "a shared reference".to_string(),938            BorrowedContentSource::DerefMutableRef => "a mutable reference".to_string(),939            BorrowedContentSource::OverloadedDeref(ty) => ty940                .ty_adt_def()941                .and_then(|adt| match tcx.get_diagnostic_name(adt.did())? {942                    name @ (sym::Rc | sym::Arc) => Some(format!("an `{name}`")),943                    _ => None,944                })945                .unwrap_or_else(|| format!("dereference of `{ty}`")),946            BorrowedContentSource::OverloadedIndex(ty) => format!("index of `{ty}`"),947        }948    }949950    pub(super) fn describe_for_named_place(&self) -> Option<&'static str> {951        match *self {952            BorrowedContentSource::DerefRawPointer => Some("raw pointer"),953            BorrowedContentSource::DerefSharedRef => Some("shared reference"),954            BorrowedContentSource::DerefMutableRef => Some("mutable reference"),955            // Overloaded deref and index operators should be evaluated into a956            // temporary. So we don't need a description here.957            BorrowedContentSource::OverloadedDeref(_)958            | BorrowedContentSource::OverloadedIndex(_) => None,959        }960    }961962    pub(super) fn describe_for_immutable_place(&self, tcx: TyCtxt<'_>) -> String {963        match *self {964            BorrowedContentSource::DerefRawPointer => "a `*const` pointer".to_string(),965            BorrowedContentSource::DerefSharedRef => "a `&` reference".to_string(),966            BorrowedContentSource::DerefMutableRef => {967                bug!("describe_for_immutable_place: DerefMutableRef isn't immutable")968            }969            BorrowedContentSource::OverloadedDeref(ty) => ty970                .ty_adt_def()971                .and_then(|adt| match tcx.get_diagnostic_name(adt.did())? {972                    name @ (sym::Rc | sym::Arc) => Some(format!("an `{name}`")),973                    _ => None,974                })975                .unwrap_or_else(|| format!("dereference of `{ty}`")),976            BorrowedContentSource::OverloadedIndex(ty) => format!("an index of `{ty}`"),977        }978    }979980    fn from_call(func: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Self> {981        match *func.kind() {982            ty::FnDef(def_id, args) => {983                let trait_id = tcx.trait_of_assoc(def_id)?;984985                if tcx.is_lang_item(trait_id, LangItem::Deref)986                    || tcx.is_lang_item(trait_id, LangItem::DerefMut)987                {988                    Some(BorrowedContentSource::OverloadedDeref(args.type_at(0)))989                } else if tcx.is_lang_item(trait_id, LangItem::Index)990                    || tcx.is_lang_item(trait_id, LangItem::IndexMut)991                {992                    Some(BorrowedContentSource::OverloadedIndex(args.type_at(0)))993                } else {994                    None995                }996            }997            _ => None,998        }999    }1000}10011002/// Helper struct for `explain_captures`.1003struct CapturedMessageOpt {1004    is_partial_move: bool,1005    is_loop_message: bool,1006    is_move_msg: bool,1007    is_loop_move: bool,1008    has_suggest_reborrow: bool,1009    maybe_reinitialized_locations_is_empty: bool,1010}10111012/// Tracks whether [`MirBorrowckCtxt::explain_captures`] emitted a clone1013/// suggestion, so callers can avoid emitting redundant suggestions downstream.1014#[derive(Copy, Clone, PartialEq, Eq)]1015pub(super) enum CloneSuggestion {1016    Emitted,1017    NotEmitted,1018}10191020impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {1021    /// Finds the spans associated to a move or copy of move_place at location.1022    pub(super) fn move_spans(1023        &self,1024        moved_place: PlaceRef<'tcx>, // Could also be an upvar.1025        location: Location,1026    ) -> UseSpans<'tcx> {1027        use self::UseSpans::*;10281029        let Some(stmt) = self.body[location.block].statements.get(location.statement_index) else {1030            return OtherUse(self.body.source_info(location).span);1031        };10321033        debug!("move_spans: moved_place={:?} location={:?} stmt={:?}", moved_place, location, stmt);1034        if let StatementKind::Assign((_, Rvalue::Aggregate(kind, places))) = &stmt.kind1035            && let AggregateKind::Closure(def_id, _) | AggregateKind::Coroutine(def_id, _) = **kind1036        {1037            debug!("move_spans: def_id={:?} places={:?}", def_id, places);1038            let def_id = def_id.expect_local();1039            if let Some((args_span, closure_kind, capture_kind_span, path_span)) =1040                self.closure_span(def_id, moved_place, places)1041            {1042                return ClosureUse { closure_kind, args_span, capture_kind_span, path_span };1043            }1044        }10451046        // StatementKind::FakeRead only contains a def_id if they are introduced as a result1047        // of pattern matching within a closure.1048        if let StatementKind::FakeRead((cause, place)) = stmt.kind {1049            match cause {1050                FakeReadCause::ForMatchedPlace(Some(closure_def_id))1051                | FakeReadCause::ForLet(Some(closure_def_id)) => {1052                    debug!("move_spans: def_id={:?} place={:?}", closure_def_id, place);1053                    let places = &[Operand::Move(place)];1054                    if let Some((args_span, closure_kind, capture_kind_span, path_span)) =1055                        self.closure_span(closure_def_id, moved_place, IndexSlice::from_raw(places))1056                    {1057                        return ClosureUse {1058                            closure_kind,1059                            args_span,1060                            capture_kind_span,1061                            path_span,1062                        };1063                    }1064                }1065                _ => {}1066            }1067        }10681069        let normal_ret =1070            if moved_place.projection.iter().any(|p| matches!(p, ProjectionElem::Downcast(..))) {1071                PatUse(stmt.source_info.span)1072            } else {1073                OtherUse(stmt.source_info.span)1074            };10751076        // We are trying to find MIR of the form:1077        // ```1078        // _temp = _moved_val;1079        // ...1080        // FnSelfCall(_temp, ...)1081        // ```1082        //1083        // where `_moved_val` is the place we generated the move error for,1084        // `_temp` is some other local, and `FnSelfCall` is a function1085        // that has a `self` parameter.10861087        let target_temp = match stmt.kind {1088            StatementKind::Assign((temp, _)) if temp.as_local().is_some() => {1089                temp.as_local().unwrap()1090            }1091            _ => return normal_ret,1092        };10931094        debug!("move_spans: target_temp = {:?}", target_temp);10951096        if let Some(Terminator {1097            kind: TerminatorKind::Call { fn_span, call_source, .. }, ..1098        }) = &self.body[location.block].terminator1099        {1100            let Some((method_did, method_args)) =1101                find_self_call(self.infcx.tcx, self.body, target_temp, location.block)1102            else {1103                return normal_ret;1104            };11051106            let kind = call_kind(1107                self.infcx.tcx,1108                self.infcx.typing_env(self.infcx.param_env),1109                method_did,1110                method_args,1111                *fn_span,1112                call_source.from_hir_call(),1113                self.infcx.tcx.fn_arg_idents(method_did)[0],1114            );11151116            return FnSelfUse {1117                var_span: stmt.source_info.span,1118                fn_call_span: *fn_span,1119                fn_span: self.infcx.tcx.def_span(method_did),1120                kind,1121            };1122        }11231124        normal_ret1125    }11261127    /// Finds the span of arguments of a closure (within `maybe_closure_span`)1128    /// and its usage of the local assigned at `location`.1129    /// This is done by searching in statements succeeding `location`1130    /// and originating from `maybe_closure_span`.1131    pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans<'tcx> {1132        use self::UseSpans::*;1133        debug!("borrow_spans: use_span={:?} location={:?}", use_span, location);11341135        let Some(Statement { kind: StatementKind::Assign((place, _)), .. }) =1136            self.body[location.block].statements.get(location.statement_index)1137        else {1138            return OtherUse(use_span);1139        };1140        let Some(target) = place.as_local() else { return OtherUse(use_span) };11411142        if self.body.local_kind(target) != LocalKind::Temp {1143            // operands are always temporaries.1144            return OtherUse(use_span);1145        }11461147        // drop and replace might have moved the assignment to the next block1148        let maybe_additional_statement =1149            if let TerminatorKind::Drop { target: drop_target, .. } =1150                self.body[location.block].terminator().kind1151            {1152                self.body[drop_target].statements.first()1153            } else {1154                None1155            };11561157        let statements =1158            self.body[location.block].statements[location.statement_index + 1..].iter();11591160        for stmt in statements.chain(maybe_additional_statement) {1161            if let StatementKind::Assign((_, Rvalue::Aggregate(kind, places))) = &stmt.kind {1162                let (&def_id, is_coroutine) = match kind {1163                    AggregateKind::Closure(def_id, _) => (def_id, false),1164                    AggregateKind::Coroutine(def_id, _) => (def_id, true),1165                    _ => continue,1166                };1167                let def_id = def_id.expect_local();11681169                debug!(1170                    "borrow_spans: def_id={:?} is_coroutine={:?} places={:?}",1171                    def_id, is_coroutine, places1172                );1173                if let Some((args_span, closure_kind, capture_kind_span, path_span)) =1174                    self.closure_span(def_id, Place::from(target).as_ref(), places)1175                {1176                    return ClosureUse { closure_kind, args_span, capture_kind_span, path_span };1177                } else {1178                    return OtherUse(use_span);1179                }1180            }11811182            if use_span != stmt.source_info.span {1183                break;1184            }1185        }11861187        OtherUse(use_span)1188    }11891190    /// Finds the spans of a captured place within a closure or coroutine.1191    /// The first span is the location of the use resulting in the capture kind of the capture1192    /// The second span is the location the use resulting in the captured path of the capture1193    fn closure_span(1194        &self,1195        def_id: LocalDefId,1196        target_place: PlaceRef<'tcx>,1197        places: &IndexSlice<FieldIdx, Operand<'tcx>>,1198    ) -> Option<(Span, hir::ClosureKind, Span, Span)> {1199        debug!(1200            "closure_span: def_id={:?} target_place={:?} places={:?}",1201            def_id, target_place, places1202        );1203        let hir_id = self.infcx.tcx.local_def_id_to_hir_id(def_id);1204        let expr = &self.infcx.tcx.hir_expect_expr(hir_id).kind;1205        debug!("closure_span: hir_id={:?} expr={:?}", hir_id, expr);1206        if let &hir::ExprKind::Closure(&hir::Closure { kind, fn_decl_span, .. }) = expr {1207            for (captured_place, place) in1208                self.infcx.tcx.closure_captures(def_id).iter().zip(places)1209            {1210                match place {1211                    Operand::Copy(place) | Operand::Move(place)1212                        if target_place == place.as_ref() =>1213                    {1214                        debug!("closure_span: found captured local {:?}", place);1215                        return Some((1216                            fn_decl_span,1217                            kind,1218                            captured_place.get_capture_kind_span(self.infcx.tcx),1219                            captured_place.get_path_span(self.infcx.tcx),1220                        ));1221                    }1222                    _ => {}1223                }1224            }1225        }1226        None1227    }12281229    /// Helper to retrieve span(s) of given borrow from the current MIR1230    /// representation1231    pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans<'tcx> {1232        let span = self.body.source_info(borrow.reserve_location).span;1233        self.borrow_spans(span, borrow.reserve_location)1234    }12351236    fn explain_captures(1237        &mut self,1238        err: &mut Diag<'infcx>,1239        span: Span,1240        move_span: Span,1241        move_spans: UseSpans<'tcx>,1242        moved_place: Place<'tcx>,1243        msg_opt: CapturedMessageOpt,1244    ) -> CloneSuggestion {1245        let CapturedMessageOpt {1246            is_partial_move: is_partial,1247            is_loop_message,1248            is_move_msg,1249            is_loop_move,1250            has_suggest_reborrow,1251            maybe_reinitialized_locations_is_empty,1252        } = msg_opt;1253        let mut suggested_cloning = false;1254        if let UseSpans::FnSelfUse { var_span, fn_call_span, fn_span, kind } = move_spans {1255            let place_name = self1256                .describe_place(moved_place.as_ref())1257                .map(|n| format!("`{n}`"))1258                .unwrap_or_else(|| "value".to_owned());1259            match kind {1260                CallKind::FnCall { fn_trait_id, self_ty }1261                    if self.infcx.tcx.is_lang_item(fn_trait_id, LangItem::FnOnce) =>1262                {1263                    err.subdiagnostic(CaptureReasonLabel::Call {1264                        fn_call_span,1265                        place_name: &place_name,1266                        is_partial,1267                        is_loop_message,1268                    });1269                    // Check if the move occurs on a value because of a call on a closure that comes1270                    // from a type parameter `F: FnOnce()`. If so, we provide a targeted `note`:1271                    // ```1272                    // error[E0382]: use of moved value: `blk`1273                    //   --> $DIR/once-cant-call-twice-on-heap.rs:8:51274                    //    |1275                    // LL | fn foo<F:FnOnce()>(blk: F) {1276                    //    |                    --- move occurs because `blk` has type `F`, which does not implement the `Copy` trait1277                    // LL | blk();1278                    //    | ----- `blk` moved due to this call1279                    // LL | blk();1280                    //    | ^^^ value used here after move1281                    //    |1282                    // note: `FnOnce` closures can only be called once1283                    //   --> $DIR/once-cant-call-twice-on-heap.rs:6:101284                    //    |1285                    // LL | fn foo<F:FnOnce()>(blk: F) {1286                    //    |        ^^^^^^^^ `F` is made to be an `FnOnce` closure here1287                    // LL | blk();1288                    //    | ----- this value implements `FnOnce`, which causes it to be moved when called1289                    // ```1290                    if let ty::Param(param_ty) = *self_ty.kind()1291                        && let generics = self.infcx.tcx.generics_of(self.mir_def_id())1292                        && let param = generics.type_param(param_ty, self.infcx.tcx)1293                        && let Some(hir_generics) = self.infcx.tcx.hir_get_generics(1294                            self.infcx.tcx.typeck_root_def_id_local(self.mir_def_id()),1295                        )1296                        && let spans = hir_generics1297                            .predicates1298                            .iter()1299                            .filter_map(|pred| match pred.kind {1300                                hir::WherePredicateKind::BoundPredicate(pred) => Some(pred),1301                                _ => None,1302                            })1303                            .filter(|pred| {1304                                if let Some((id, _)) = pred.bounded_ty.as_generic_param() {1305                                    id == param.def_id1306                                } else {1307                                    false1308                                }1309                            })1310                            .flat_map(|pred| pred.bounds)1311                            .filter_map(|bound| {1312                                if let Some(trait_ref) = bound.trait_ref()1313                                    && let Some(trait_def_id) = trait_ref.trait_def_id()1314                                    && trait_def_id == fn_trait_id1315                                {1316                                    Some(bound.span())1317                                } else {1318                                    None1319                                }1320                            })1321                            .collect::<Vec<Span>>()1322                        && !spans.is_empty()1323                    {1324                        let mut span: MultiSpan = spans.clone().into();1325                        let msg = msg!("`{$ty}` is made to be an `FnOnce` closure here")1326                            .arg("ty", param_ty.to_string())1327                            .format();1328                        for sp in spans {1329                            span.push_span_label(sp, msg.clone());1330                        }1331                        span.push_span_label(1332                            fn_call_span,1333                            msg!("this value implements `FnOnce`, which causes it to be moved when called"),1334                        );1335                        err.span_note(span, msg!("`FnOnce` closures can only be called once"));1336                    } else {1337                        err.subdiagnostic(CaptureReasonNote::FnOnceMoveInCall { var_span });1338                    }1339                }1340                CallKind::Operator { self_arg, trait_id, .. } => {1341                    let self_arg = self_arg.unwrap();1342                    err.subdiagnostic(CaptureReasonLabel::OperatorUse {1343                        fn_call_span,1344                        place_name: &place_name,1345                        is_partial,1346                        is_loop_message,1347                    });1348                    if self.fn_self_span_reported.insert(fn_span) {1349                        let lang = self.infcx.tcx.lang_items();1350                        err.subdiagnostic(1351                            if [lang.not_trait(), lang.deref_trait(), lang.neg_trait()]1352                                .contains(&Some(trait_id))1353                            {1354                                CaptureReasonNote::UnOpMoveByOperator { span: self_arg.span }1355                            } else {1356                                CaptureReasonNote::LhsMoveByOperator { span: self_arg.span }1357                            },1358                        );1359                    }1360                }1361                CallKind::Normal { self_arg, desugaring, method_did, method_args } => {1362                    let self_arg = self_arg.unwrap();1363                    let mut has_sugg = false;1364                    let tcx = self.infcx.tcx;1365                    // Avoid pointing to the same function in multiple different1366                    // error messages.1367                    if span != DUMMY_SP && self.fn_self_span_reported.insert(self_arg.span) {1368                        self.explain_iterator_advancement_in_for_loop_if_applicable(1369                            err,1370                            span,1371                            &move_spans,1372                        );13731374                        let func = tcx.def_path_str(method_did);1375                        err.subdiagnostic(CaptureReasonNote::FuncTakeSelf {1376                            func,1377                            place_name: place_name.clone(),1378                            span: self_arg.span,1379                        });1380                    }1381                    let parent_did = tcx.parent(method_did);1382                    let parent_self_ty =1383                        matches!(tcx.def_kind(parent_did), rustc_hir::def::DefKind::Impl { .. })1384                            .then_some(parent_did)1385                            .and_then(|did| {1386                                match tcx.type_of(did).instantiate_identity().skip_norm_wip().kind()1387                                {1388                                    ty::Adt(def, ..) => Some(def.did()),1389                                    _ => None,1390                                }1391                            });1392                    let is_option_or_result = parent_self_ty.is_some_and(|def_id| {1393                        matches!(tcx.get_diagnostic_name(def_id), Some(sym::Option | sym::Result))1394                    });1395                    if is_option_or_result && maybe_reinitialized_locations_is_empty {1396                        err.subdiagnostic(CaptureReasonLabel::BorrowContent {1397                            var_span: var_span.shrink_to_hi(),1398                        });1399                    }1400                    if let Some((CallDesugaringKind::ForLoopIntoIter, _)) = desugaring {1401                        let ty = moved_place.ty(self.body, tcx).ty;1402                        let suggest = match tcx.get_diagnostic_item(sym::IntoIterator) {1403                            Some(def_id) => type_known_to_meet_bound_modulo_regions(1404                                self.infcx,1405                                self.infcx.param_env,1406                                Ty::new_imm_ref(tcx, tcx.lifetimes.re_erased, ty),1407                                def_id,1408                            ),1409                            _ => false,1410                        };1411                        if suggest {1412                            err.subdiagnostic(CaptureReasonSuggest::IterateSlice {1413                                ty,1414                                span: move_span.shrink_to_lo(),1415                            });1416                        }14171418                        err.subdiagnostic(CaptureReasonLabel::ImplicitCall {1419                            fn_call_span,1420                            place_name: &place_name,1421                            is_partial,1422                            is_loop_message,1423                        });1424                        // If the moved place was a `&mut` ref, then we can1425                        // suggest to reborrow it where it was moved, so it1426                        // will still be valid by the time we get to the usage.1427                        if let ty::Ref(_, _, hir::Mutability::Mut) =1428                            moved_place.ty(self.body, self.infcx.tcx).ty.kind()1429                        {1430                            // The `&mut *place` reborrow suggestion is `MachineApplicable`, so1431                            // only offer it where `*place` can be borrowed mutably: a value1432                            // captured by an `Fn` closure (held via `&self`) cannot, and the1433                            // suggestion would otherwise fail to compile with E0596.1434                            let reborrow_place = self.infcx.tcx.mk_place_deref(moved_place);1435                            let reborrow_is_valid = self1436                                .is_mutable(reborrow_place.as_ref(), LocalMutationIsAllowed::No)1437                                .is_ok();1438                            // Suggest `reborrow` in other place for following situations:1439                            // 1. If we are in a loop this will be suggested later.1440                            // 2. If the moved value is a mut reference, it is used in a1441                            // generic function and the corresponding arg's type is generic param.1442                            if !is_loop_move && !has_suggest_reborrow && reborrow_is_valid {1443                                self.suggest_reborrow(1444                                    err,1445                                    move_span.shrink_to_lo(),1446                                    moved_place.as_ref(),1447                                );1448                            }1449                        }1450                    } else {1451                        if let Some((CallDesugaringKind::Await, _)) = desugaring {1452                            err.subdiagnostic(CaptureReasonLabel::Await {1453                                fn_call_span,1454                                place_name: &place_name,1455                                is_partial,1456                                is_loop_message,1457                            });1458                        } else {1459                            err.subdiagnostic(CaptureReasonLabel::MethodCall {1460                                fn_call_span,1461                                place_name: &place_name,1462                                is_partial,1463                                is_loop_message,1464                            });1465                        }1466                        // Erase and shadow everything that could be passed to the new infcx.1467                        let ty = moved_place.ty(self.body, tcx).ty;14681469                        if let ty::Adt(def, args) = ty.peel_refs().kind()1470                            && tcx.is_lang_item(def.did(), LangItem::Pin)1471                            && let ty::Ref(_, _, hir::Mutability::Mut) = args.type_at(0).kind()1472                            && let self_ty = self.infcx.instantiate_binder_with_fresh_vars(1473                                fn_call_span,1474                                BoundRegionConversionTime::FnCall,1475                                tcx.fn_sig(method_did)1476                                    .instantiate(tcx, method_args)1477                                    .skip_norm_wip()1478                                    .input(0),1479                            )1480                            && self.infcx.can_eq(self.infcx.param_env, ty, self_ty)1481                        {1482                            err.subdiagnostic(CaptureReasonSuggest::FreshReborrow {1483                                span: move_span.shrink_to_hi(),1484                            });1485                            has_sugg = true;1486                        }1487                        if let Some(clone_trait) = tcx.lang_items().clone_trait() {1488                            // Check whether the deref is from a custom Deref impl1489                            // (e.g. Rc, Box) or a built-in reference deref.1490                            // For built-in derefs with Clone fully satisfied, we skip1491                            // the UFCS suggestion here and let `suggest_cloning`1492                            // downstream emit a simpler `.clone()` suggestion instead.1493                            let has_overloaded_deref =1494                                moved_place.iter_projections().any(|(place, elem)| {1495                                    matches!(elem, ProjectionElem::Deref)1496                                        && matches!(1497                                            self.borrowed_content_source(place),1498                                            BorrowedContentSource::OverloadedDeref(_)1499                                                | BorrowedContentSource::OverloadedIndex(_)1500                                        )1501                                });15021503                            let has_deref = moved_place1504                                .iter_projections()1505                                .any(|(_, elem)| matches!(elem, ProjectionElem::Deref));15061507                            let sugg = if has_deref {1508                                let (start, end) = if let Some(expr) = self.find_expr(move_span)1509                                    && let Some(_) = self.clone_on_reference(expr)1510                                    && let hir::ExprKind::MethodCall(_, rcvr, _, _) = expr.kind1511                                {1512                                    (move_span.shrink_to_lo(), move_span.with_lo(rcvr.span.hi()))1513                                } else {1514                                    (move_span.shrink_to_lo(), move_span.shrink_to_hi())1515                                };1516                                vec![1517                                    // We use the fully-qualified path because `.clone()` can1518                                    // sometimes choose `<&T as Clone>` instead of `<T as Clone>`1519                                    // when going through auto-deref, so this ensures that doesn't1520                                    // happen, causing suggestions for `.clone().clone()`.1521                                    (start, format!("<{ty} as Clone>::clone(&")),1522                                    (end, ")".to_string()),1523                                ]1524                            } else {1525                                vec![(move_span.shrink_to_hi(), ".clone()".to_string())]1526                            };1527                            if let Some(errors) = self.infcx.type_implements_trait_shallow(1528                                clone_trait,1529                                ty,1530                                self.infcx.param_env,1531                            ) && !has_sugg1532                            {1533                                let skip_for_simple_clone =1534                                    has_deref && !has_overloaded_deref && errors.is_empty();1535                                if !skip_for_simple_clone {1536                                    let msg = match &errors[..] {1537                                        [] => "you can `clone` the value and consume it, but \1538                                               this might not be your desired behavior"1539                                            .to_string(),1540                                        [error] => {1541                                            format!(1542                                                "you could `clone` the value and consume it, if \1543                                                 the `{}` trait bound could be satisfied",1544                                                error.obligation.predicate,1545                                            )1546                                        }1547                                        _ => {1548                                            format!(1549                                                "you could `clone` the value and consume it, if \1550                                                 the following trait bounds could be satisfied: \1551                                                 {}",1552                                                listify(1553                                                    &errors,1554                                                    |e: &FulfillmentError<'tcx>| format!(1555                                                        "`{}`",1556                                                        e.obligation.predicate1557                                                    )1558                                                )1559                                                .unwrap(),1560                                            )1561                                        }1562                                    };1563                                    err.multipart_suggestion(1564                                        msg,1565                                        sugg,1566                                        Applicability::MaybeIncorrect,1567                                    );15681569                                    suggested_cloning = errors.is_empty();15701571                                    for error in errors {1572                                        if let FulfillmentErrorCode::Select(1573                                            SelectionError::Unimplemented,1574                                        ) = error.code1575                                            && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(1576                                                pred,1577                                            )) = error.obligation.predicate.kind().skip_binder()1578                                        {1579                                            self.infcx.err_ctxt().suggest_derive(1580                                                &error.obligation,1581                                                err,1582                                                error.obligation.predicate.kind().rebind(pred),1583                                            );1584                                        }1585                                    }1586                                }1587                            }1588                        }1589                    }1590                }1591                // Other desugarings takes &self, which cannot cause a move1592                _ => {}1593            }1594        } else {1595            if move_span != span || is_loop_message {1596                err.subdiagnostic(CaptureReasonLabel::MovedHere {1597                    move_span,1598                    is_partial,1599                    is_move_msg,1600                    is_loop_message,1601                });1602            }1603            // If the move error occurs due to a loop, don't show1604            // another message for the same span1605            if !is_loop_message {1606                move_spans.var_subdiag(err, None, |kind, var_span| match kind {1607                    hir::ClosureKind::Coroutine(_) => {1608                        CaptureVarCause::PartialMoveUseInCoroutine { var_span, is_partial }1609                    }1610                    hir::ClosureKind::Closure | hir::ClosureKind::CoroutineClosure(_) => {1611                        CaptureVarCause::PartialMoveUseInClosure { var_span, is_partial }1612                    }1613                })1614            }1615        }1616        if suggested_cloning { CloneSuggestion::Emitted } else { CloneSuggestion::NotEmitted }1617    }16181619    /// Skip over locals that begin with an underscore or have no name1620    pub(crate) fn local_excluded_from_unused_mut_lint(&self, index: Local) -> bool {1621        self.local_name(index).is_none_or(|name| name.as_str().starts_with('_'))1622    }1623}16241625const LIMITATION_NOTE: DiagMessage =1626    msg!("due to a current limitation of the type system, this implies a `'static` lifetime");