| #![allow(rustc::diagnostic_outside_of_impl)] |
| #![allow(rustc::untranslatable_diagnostic)] |
| |
| use rustc_data_structures::fx::FxHashSet; |
| use rustc_errors::{Applicability, Diag}; |
| use rustc_hir::intravisit::Visitor; |
| use rustc_hir::{self as hir, CaptureBy, ExprKind, HirId, Node}; |
| use rustc_middle::bug; |
| use rustc_middle::mir::*; |
| use rustc_middle::ty::{self, Ty, TyCtxt}; |
| use rustc_mir_dataflow::move_paths::{LookupResult, MovePathIndex}; |
| use rustc_span::{BytePos, ExpnKind, MacroKind, Span}; |
| use rustc_trait_selection::error_reporting::traits::FindExprBySpan; |
| use rustc_trait_selection::infer::InferCtxtExt; |
| use tracing::debug; |
| |
| use crate::MirBorrowckCtxt; |
| use crate::diagnostics::{CapturedMessageOpt, DescribePlaceOpt, UseSpans}; |
| use crate::prefixes::PrefixSet; |
| |
| #[derive(Debug)] |
| pub(crate) enum IllegalMoveOriginKind<'tcx> { |
| /// Illegal move due to attempt to move from behind a reference. |
| BorrowedContent { |
| /// The place the reference refers to: if erroneous code was trying to |
| /// move from `(*x).f` this will be `*x`. |
| target_place: Place<'tcx>, |
| }, |
| |
| /// Illegal move due to attempt to move from field of an ADT that |
| /// implements `Drop`. Rust maintains invariant that all `Drop` |
| /// ADT's remain fully-initialized so that user-defined destructor |
| /// can safely read from all of the ADT's fields. |
| InteriorOfTypeWithDestructor { container_ty: Ty<'tcx> }, |
| |
| /// Illegal move due to attempt to move out of a slice or array. |
| InteriorOfSliceOrArray { ty: Ty<'tcx>, is_index: bool }, |
| } |
| |
| #[derive(Debug)] |
| pub(crate) struct MoveError<'tcx> { |
| place: Place<'tcx>, |
| location: Location, |
| kind: IllegalMoveOriginKind<'tcx>, |
| } |
| |
| impl<'tcx> MoveError<'tcx> { |
| pub(crate) fn new( |
| place: Place<'tcx>, |
| location: Location, |
| kind: IllegalMoveOriginKind<'tcx>, |
| ) -> Self { |
| MoveError { place, location, kind } |
| } |
| } |
| |
| // Often when desugaring a pattern match we may have many individual moves in |
| // MIR that are all part of one operation from the user's point-of-view. For |
| // example: |
| // |
| // let (x, y) = foo() |
| // |
| // would move x from the 0 field of some temporary, and y from the 1 field. We |
| // group such errors together for cleaner error reporting. |
| // |
| // Errors are kept separate if they are from places with different parent move |
| // paths. For example, this generates two errors: |
| // |
| // let (&x, &y) = (&String::new(), &String::new()); |
| #[derive(Debug)] |
| enum GroupedMoveError<'tcx> { |
| // Place expression can't be moved from, |
| // e.g., match x[0] { s => (), } where x: &[String] |
| MovesFromPlace { |
| original_path: Place<'tcx>, |
| span: Span, |
| move_from: Place<'tcx>, |
| kind: IllegalMoveOriginKind<'tcx>, |
| binds_to: Vec<Local>, |
| }, |
| // Part of a value expression can't be moved from, |
| // e.g., match &String::new() { &x => (), } |
| MovesFromValue { |
| original_path: Place<'tcx>, |
| span: Span, |
| move_from: MovePathIndex, |
| kind: IllegalMoveOriginKind<'tcx>, |
| binds_to: Vec<Local>, |
| }, |
| // Everything that isn't from pattern matching. |
| OtherIllegalMove { |
| original_path: Place<'tcx>, |
| use_spans: UseSpans<'tcx>, |
| kind: IllegalMoveOriginKind<'tcx>, |
| }, |
| } |
| |
| impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> { |
| pub(crate) fn report_move_errors(&mut self) { |
| let grouped_errors = self.group_move_errors(); |
| for error in grouped_errors { |
| self.report(error); |
| } |
| } |
| |
| fn group_move_errors(&mut self) -> Vec<GroupedMoveError<'tcx>> { |
| let mut grouped_errors = Vec::new(); |
| let errors = std::mem::take(&mut self.move_errors); |
| for error in errors { |
| self.append_to_grouped_errors(&mut grouped_errors, error); |
| } |
| grouped_errors |
| } |
| |
| fn append_to_grouped_errors( |
| &self, |
| grouped_errors: &mut Vec<GroupedMoveError<'tcx>>, |
| MoveError { place: original_path, location, kind }: MoveError<'tcx>, |
| ) { |
| // Note: that the only time we assign a place isn't a temporary |
| // to a user variable is when initializing it. |
| // If that ever stops being the case, then the ever initialized |
| // flow could be used. |
| if let Some(StatementKind::Assign(box (place, Rvalue::Use(Operand::Move(move_from))))) = |
| self.body.basic_blocks[location.block] |
| .statements |
| .get(location.statement_index) |
| .map(|stmt| &stmt.kind) |
| && let Some(local) = place.as_local() |
| { |
| let local_decl = &self.body.local_decls[local]; |
| // opt_match_place is the |
| // match_span is the span of the expression being matched on |
| // match *x.y { ... } match_place is Some(*x.y) |
| // ^^^^ match_span is the span of *x.y |
| // |
| // opt_match_place is None for let [mut] x = ... statements, |
| // whether or not the right-hand side is a place expression |
| if let LocalInfo::User(BindingForm::Var(VarBindingForm { |
| opt_match_place: Some((opt_match_place, match_span)), |
| binding_mode: _, |
| opt_ty_info: _, |
| pat_span: _, |
| })) = *local_decl.local_info() |
| { |
| let stmt_source_info = self.body.source_info(location); |
| self.append_binding_error( |
| grouped_errors, |
| kind, |
| original_path, |
| *move_from, |
| local, |
| opt_match_place, |
| match_span, |
| stmt_source_info.span, |
| ); |
| return; |
| } |
| } |
| |
| let move_spans = self.move_spans(original_path.as_ref(), location); |
| grouped_errors.push(GroupedMoveError::OtherIllegalMove { |
| use_spans: move_spans, |
| original_path, |
| kind, |
| }); |
| } |
| |
| fn append_binding_error( |
| &self, |
| grouped_errors: &mut Vec<GroupedMoveError<'tcx>>, |
| kind: IllegalMoveOriginKind<'tcx>, |
| original_path: Place<'tcx>, |
| move_from: Place<'tcx>, |
| bind_to: Local, |
| match_place: Option<Place<'tcx>>, |
| match_span: Span, |
| statement_span: Span, |
| ) { |
| debug!(?match_place, ?match_span, "append_binding_error"); |
| |
| let from_simple_let = match_place.is_none(); |
| let match_place = match_place.unwrap_or(move_from); |
| |
| match self.move_data.rev_lookup.find(match_place.as_ref()) { |
| // Error with the match place |
| LookupResult::Parent(_) => { |
| for ge in &mut *grouped_errors { |
| if let GroupedMoveError::MovesFromPlace { span, binds_to, .. } = ge |
| && match_span == *span |
| { |
| debug!("appending local({bind_to:?}) to list"); |
| if !binds_to.is_empty() { |
| binds_to.push(bind_to); |
| } |
| return; |
| } |
| } |
| debug!("found a new move error location"); |
| |
| // Don't need to point to x in let x = ... . |
| let (binds_to, span) = if from_simple_let { |
| (vec![], statement_span) |
| } else { |
| (vec![bind_to], match_span) |
| }; |
| grouped_errors.push(GroupedMoveError::MovesFromPlace { |
| span, |
| move_from, |
| original_path, |
| kind, |
| binds_to, |
| }); |
| } |
| // Error with the pattern |
| LookupResult::Exact(_) => { |
| let LookupResult::Parent(Some(mpi)) = |
| self.move_data.rev_lookup.find(move_from.as_ref()) |
| else { |
| // move_from should be a projection from match_place. |
| unreachable!("Probably not unreachable..."); |
| }; |
| for ge in &mut *grouped_errors { |
| if let GroupedMoveError::MovesFromValue { |
| span, |
| move_from: other_mpi, |
| binds_to, |
| .. |
| } = ge |
| { |
| if match_span == *span && mpi == *other_mpi { |
| debug!("appending local({bind_to:?}) to list"); |
| binds_to.push(bind_to); |
| return; |
| } |
| } |
| } |
| debug!("found a new move error location"); |
| grouped_errors.push(GroupedMoveError::MovesFromValue { |
| span: match_span, |
| move_from: mpi, |
| original_path, |
| kind, |
| binds_to: vec![bind_to], |
| }); |
| } |
| }; |
| } |
| |
| fn report(&mut self, error: GroupedMoveError<'tcx>) { |
| let (span, use_spans, original_path, kind) = match error { |
| GroupedMoveError::MovesFromPlace { span, original_path, ref kind, .. } |
| | GroupedMoveError::MovesFromValue { span, original_path, ref kind, .. } => { |
| (span, None, original_path, kind) |
| } |
| GroupedMoveError::OtherIllegalMove { use_spans, original_path, ref kind } => { |
| (use_spans.args_or_use(), Some(use_spans), original_path, kind) |
| } |
| }; |
| debug!( |
| "report: original_path={:?} span={:?}, kind={:?} \ |
| original_path.is_upvar_field_projection={:?}", |
| original_path, |
| span, |
| kind, |
| self.is_upvar_field_projection(original_path.as_ref()) |
| ); |
| if self.has_ambiguous_copy(original_path.ty(self.body, self.infcx.tcx).ty) { |
| // If the type may implement Copy, skip the error. |
| // It's an error with the Copy implementation (e.g. duplicate Copy) rather than borrow check |
| self.dcx() |
| .span_delayed_bug(span, "Type may implement copy, but there is no other error."); |
| return; |
| } |
| let mut err = match kind { |
| &IllegalMoveOriginKind::BorrowedContent { target_place } => self |
| .report_cannot_move_from_borrowed_content( |
| original_path, |
| target_place, |
| span, |
| use_spans, |
| ), |
| &IllegalMoveOriginKind::InteriorOfTypeWithDestructor { container_ty: ty } => { |
| self.cannot_move_out_of_interior_of_drop(span, ty) |
| } |
| &IllegalMoveOriginKind::InteriorOfSliceOrArray { ty, is_index } => { |
| self.cannot_move_out_of_interior_noncopy(span, ty, Some(is_index)) |
| } |
| }; |
| |
| self.add_move_hints(error, &mut err, span); |
| self.buffer_error(err); |
| } |
| |
| fn has_ambiguous_copy(&mut self, ty: Ty<'tcx>) -> bool { |
| let Some(copy_def_id) = self.infcx.tcx.lang_items().copy_trait() else { return false }; |
| |
| // Avoid bogus move errors because of an incoherent `Copy` impl. |
| self.infcx.type_implements_trait(copy_def_id, [ty], self.infcx.param_env).may_apply() |
| && self.infcx.tcx.coherent_trait(copy_def_id).is_err() |
| } |
| |
| fn report_cannot_move_from_static(&mut self, place: Place<'tcx>, span: Span) -> Diag<'infcx> { |
| let description = if place.projection.len() == 1 { |
| format!("static item {}", self.describe_any_place(place.as_ref())) |
| } else { |
| let base_static = PlaceRef { local: place.local, projection: &[ProjectionElem::Deref] }; |
| |
| format!( |
| "{} as {} is a static item", |
| self.describe_any_place(place.as_ref()), |
| self.describe_any_place(base_static), |
| ) |
| }; |
| |
| self.cannot_move_out_of(span, &description) |
| } |
| |
| pub(in crate::diagnostics) fn suggest_clone_of_captured_var_in_move_closure( |
| &self, |
| err: &mut Diag<'_>, |
| upvar_name: &str, |
| use_spans: Option<UseSpans<'tcx>>, |
| ) { |
| let tcx = self.infcx.tcx; |
| let Some(use_spans) = use_spans else { return }; |
| // We only care about the case where a closure captured a binding. |
| let UseSpans::ClosureUse { args_span, .. } = use_spans else { return }; |
| let Some(body_id) = tcx.hir_node(self.mir_hir_id()).body_id() else { return }; |
| // Find the closure that captured the binding. |
| let mut expr_finder = FindExprBySpan::new(args_span, tcx); |
| expr_finder.include_closures = true; |
| expr_finder.visit_expr(tcx.hir_body(body_id).value); |
| let Some(closure_expr) = expr_finder.result else { return }; |
| let ExprKind::Closure(closure) = closure_expr.kind else { return }; |
| // We'll only suggest cloning the binding if it's a `move` closure. |
| let CaptureBy::Value { .. } = closure.capture_clause else { return }; |
| // Find the expression within the closure where the binding is consumed. |
| let mut suggested = false; |
| let use_span = use_spans.var_or_use(); |
| let mut expr_finder = FindExprBySpan::new(use_span, tcx); |
| expr_finder.include_closures = true; |
| expr_finder.visit_expr(tcx.hir_body(body_id).value); |
| let Some(use_expr) = expr_finder.result else { return }; |
| let parent = tcx.parent_hir_node(use_expr.hir_id); |
| if let Node::Expr(expr) = parent |
| && let ExprKind::Assign(lhs, ..) = expr.kind |
| && lhs.hir_id == use_expr.hir_id |
| { |
| // Cloning the value being assigned makes no sense: |
| // |
| // error[E0507]: cannot move out of `var`, a captured variable in an `FnMut` closure |
| // --> $DIR/option-content-move2.rs:11:9 |
| // | |
| // LL | let mut var = None; |
| // | ------- captured outer variable |
| // LL | func(|| { |
| // | -- captured by this `FnMut` closure |
| // LL | // Shouldn't suggest `move ||.as_ref()` here |
| // LL | move || { |
| // | ^^^^^^^ `var` is moved here |
| // LL | |
| // LL | var = Some(NotCopyable); |
| // | --- |
| // | | |
| // | variable moved due to use in closure |
| // | move occurs because `var` has type `Option<NotCopyable>`, which does not implement the `Copy` trait |
| // | |
| return; |
| } |
| |
| // Search for an appropriate place for the structured `.clone()` suggestion to be applied. |
| // If we encounter a statement before the borrow error, we insert a statement there. |
| for (_, node) in tcx.hir_parent_iter(closure_expr.hir_id) { |
| if let Node::Stmt(stmt) = node { |
| let padding = tcx |
| .sess |
| .source_map() |
| .indentation_before(stmt.span) |
| .unwrap_or_else(|| " ".to_string()); |
| err.multipart_suggestion_verbose( |
| "consider cloning the value before moving it into the closure", |
| vec![ |
| ( |
| stmt.span.shrink_to_lo(), |
| format!("let value = {upvar_name}.clone();\n{padding}"), |
| ), |
| (use_span, "value".to_string()), |
| ], |
| Applicability::MachineApplicable, |
| ); |
| suggested = true; |
| break; |
| } else if let Node::Expr(expr) = node |
| && let ExprKind::Closure(_) = expr.kind |
| { |
| // We want to suggest cloning only on the first closure, not |
| // subsequent ones (like `ui/suggestions/option-content-move2.rs`). |
| break; |
| } |
| } |
| if !suggested { |
| // If we couldn't find a statement for us to insert a new `.clone()` statement before, |
| // we have a bare expression, so we suggest the creation of a new block inline to go |
| // from `move || val` to `{ let value = val.clone(); move || value }`. |
| let padding = tcx |
| .sess |
| .source_map() |
| .indentation_before(closure_expr.span) |
| .unwrap_or_else(|| " ".to_string()); |
| err.multipart_suggestion_verbose( |
| "consider cloning the value before moving it into the closure", |
| vec![ |
| ( |
| closure_expr.span.shrink_to_lo(), |
| format!("{{\n{padding}let value = {upvar_name}.clone();\n{padding}"), |
| ), |
| (use_spans.var_or_use(), "value".to_string()), |
| (closure_expr.span.shrink_to_hi(), format!("\n{padding}}}")), |
| ], |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| fn report_cannot_move_from_borrowed_content( |
| &mut self, |
| move_place: Place<'tcx>, |
| deref_target_place: Place<'tcx>, |
| span: Span, |
| use_spans: Option<UseSpans<'tcx>>, |
| ) -> Diag<'infcx> { |
| let tcx = self.infcx.tcx; |
| // Inspect the type of the content behind the |
| // borrow to provide feedback about why this |
| // was a move rather than a copy. |
| let ty = deref_target_place.ty(self.body, tcx).ty; |
| let upvar_field = self |
| .prefixes(move_place.as_ref(), PrefixSet::All) |
| .find_map(|p| self.is_upvar_field_projection(p)); |
| |
| let deref_base = match deref_target_place.projection.as_ref() { |
| [proj_base @ .., ProjectionElem::Deref] => { |
| PlaceRef { local: deref_target_place.local, projection: proj_base } |
| } |
| _ => bug!("deref_target_place is not a deref projection"), |
| }; |
| |
| if let PlaceRef { local, projection: [] } = deref_base { |
| let decl = &self.body.local_decls[local]; |
| let local_name = self.local_name(local).map(|sym| format!("`{sym}`")); |
| if decl.is_ref_for_guard() { |
| return self |
| .cannot_move_out_of( |
| span, |
| &format!( |
| "{} in pattern guard", |
| local_name.as_deref().unwrap_or("the place") |
| ), |
| ) |
| .with_note( |
| "variables bound in patterns cannot be moved from \ |
| until after the end of the pattern guard", |
| ); |
| } else if decl.is_ref_to_static() { |
| return self.report_cannot_move_from_static(move_place, span); |
| } |
| } |
| |
| debug!("report: ty={:?}", ty); |
| let mut err = match ty.kind() { |
| ty::Array(..) | ty::Slice(..) => { |
| self.cannot_move_out_of_interior_noncopy(span, ty, None) |
| } |
| ty::Closure(def_id, closure_args) |
| if def_id.as_local() == Some(self.mir_def_id()) |
| && let Some(upvar_field) = upvar_field => |
| { |
| let closure_kind_ty = closure_args.as_closure().kind_ty(); |
| let closure_kind = match closure_kind_ty.to_opt_closure_kind() { |
| Some(kind @ (ty::ClosureKind::Fn | ty::ClosureKind::FnMut)) => kind, |
| Some(ty::ClosureKind::FnOnce) => { |
| bug!("closure kind does not match first argument type") |
| } |
| None => bug!("closure kind not inferred by borrowck"), |
| }; |
| let capture_description = |
| format!("captured variable in an `{closure_kind}` closure"); |
| |
| let upvar = &self.upvars[upvar_field.index()]; |
| let upvar_hir_id = upvar.get_root_variable(); |
| let upvar_name = upvar.to_string(tcx); |
| let upvar_span = tcx.hir_span(upvar_hir_id); |
| |
| let place_name = self.describe_any_place(move_place.as_ref()); |
| |
| let place_description = |
| if self.is_upvar_field_projection(move_place.as_ref()).is_some() { |
| format!("{place_name}, a {capture_description}") |
| } else { |
| format!("{place_name}, as `{upvar_name}` is a {capture_description}") |
| }; |
| |
| debug!( |
| "report: closure_kind_ty={:?} closure_kind={:?} place_description={:?}", |
| closure_kind_ty, closure_kind, place_description, |
| ); |
| |
| let closure_span = tcx.def_span(def_id); |
| self.cannot_move_out_of(span, &place_description) |
| .with_span_label(upvar_span, "captured outer variable") |
| .with_span_label( |
| closure_span, |
| format!("captured by this `{closure_kind}` closure"), |
| ) |
| } |
| _ => { |
| let source = self.borrowed_content_source(deref_base); |
| let move_place_ref = move_place.as_ref(); |
| match ( |
| self.describe_place_with_options( |
| move_place_ref, |
| DescribePlaceOpt { |
| including_downcast: false, |
| including_tuple_field: false, |
| }, |
| ), |
| self.describe_name(move_place_ref), |
| source.describe_for_named_place(), |
| ) { |
| (Some(place_desc), Some(name), Some(source_desc)) => self.cannot_move_out_of( |
| span, |
| &format!("`{place_desc}` as enum variant `{name}` which is behind a {source_desc}"), |
| ), |
| (Some(place_desc), Some(name), None) => self.cannot_move_out_of( |
| span, |
| &format!("`{place_desc}` as enum variant `{name}`"), |
| ), |
| (Some(place_desc), _, Some(source_desc)) => self.cannot_move_out_of( |
| span, |
| &format!("`{place_desc}` which is behind a {source_desc}"), |
| ), |
| (_, _, _) => self.cannot_move_out_of( |
| span, |
| &source.describe_for_unnamed_place(tcx), |
| ), |
| } |
| } |
| }; |
| let msg_opt = CapturedMessageOpt { |
| is_partial_move: false, |
| is_loop_message: false, |
| is_move_msg: false, |
| is_loop_move: false, |
| has_suggest_reborrow: false, |
| maybe_reinitialized_locations_is_empty: true, |
| }; |
| if let Some(use_spans) = use_spans { |
| self.explain_captures(&mut err, span, span, use_spans, move_place, msg_opt); |
| } |
| err |
| } |
| |
| fn add_move_hints(&self, error: GroupedMoveError<'tcx>, err: &mut Diag<'_>, span: Span) { |
| match error { |
| GroupedMoveError::MovesFromPlace { mut binds_to, move_from, .. } => { |
| self.add_borrow_suggestions(err, span); |
| if binds_to.is_empty() { |
| let place_ty = move_from.ty(self.body, self.infcx.tcx).ty; |
| let place_desc = match self.describe_place(move_from.as_ref()) { |
| Some(desc) => format!("`{desc}`"), |
| None => "value".to_string(), |
| }; |
| |
| if let Some(expr) = self.find_expr(span) { |
| self.suggest_cloning(err, move_from.as_ref(), place_ty, expr, None); |
| } |
| |
| err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label { |
| is_partial_move: false, |
| ty: place_ty, |
| place: &place_desc, |
| span, |
| }); |
| } else { |
| binds_to.sort(); |
| binds_to.dedup(); |
| |
| self.add_move_error_details(err, &binds_to); |
| } |
| } |
| GroupedMoveError::MovesFromValue { mut binds_to, .. } => { |
| binds_to.sort(); |
| binds_to.dedup(); |
| self.add_move_error_suggestions(err, &binds_to); |
| self.add_move_error_details(err, &binds_to); |
| } |
| // No binding. Nothing to suggest. |
| GroupedMoveError::OtherIllegalMove { ref original_path, use_spans, .. } => { |
| let mut use_span = use_spans.var_or_use(); |
| let place_ty = original_path.ty(self.body, self.infcx.tcx).ty; |
| let place_desc = match self.describe_place(original_path.as_ref()) { |
| Some(desc) => format!("`{desc}`"), |
| None => "value".to_string(), |
| }; |
| |
| if let Some(expr) = self.find_expr(use_span) { |
| self.suggest_cloning( |
| err, |
| original_path.as_ref(), |
| place_ty, |
| expr, |
| Some(use_spans), |
| ); |
| } |
| |
| if let Some(upvar_field) = self |
| .prefixes(original_path.as_ref(), PrefixSet::All) |
| .find_map(|p| self.is_upvar_field_projection(p)) |
| { |
| // Look for the introduction of the original binding being moved. |
| let upvar = &self.upvars[upvar_field.index()]; |
| let upvar_hir_id = upvar.get_root_variable(); |
| use_span = match self.infcx.tcx.parent_hir_node(upvar_hir_id) { |
| hir::Node::Param(param) => { |
| // Instead of pointing at the path where we access the value within a |
| // closure, we point at the type of the outer `fn` argument. |
| param.ty_span |
| } |
| hir::Node::LetStmt(stmt) => match (stmt.ty, stmt.init) { |
| // We point at the type of the outer let-binding. |
| (Some(ty), _) => ty.span, |
| // We point at the initializer of the outer let-binding, but only if it |
| // isn't something that spans multiple lines, like a closure, as the |
| // ASCII art gets messy. |
| (None, Some(init)) |
| if !self.infcx.tcx.sess.source_map().is_multiline(init.span) => |
| { |
| init.span |
| } |
| _ => use_span, |
| }, |
| _ => use_span, |
| }; |
| } |
| |
| err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label { |
| is_partial_move: false, |
| ty: place_ty, |
| place: &place_desc, |
| span: use_span, |
| }); |
| |
| let mut pointed_at_span = false; |
| use_spans.args_subdiag(err, |args_span| { |
| if args_span == span || args_span == use_span { |
| pointed_at_span = true; |
| } |
| crate::session_diagnostics::CaptureArgLabel::MoveOutPlace { |
| place: place_desc.clone(), |
| args_span, |
| } |
| }); |
| if !pointed_at_span && use_span != span { |
| err.subdiagnostic(crate::session_diagnostics::CaptureArgLabel::MoveOutPlace { |
| place: place_desc, |
| args_span: span, |
| }); |
| } |
| |
| self.add_note_for_packed_struct_derive(err, original_path.local); |
| } |
| } |
| } |
| |
| fn add_borrow_suggestions(&self, err: &mut Diag<'_>, span: Span) { |
| match self.infcx.tcx.sess.source_map().span_to_snippet(span) { |
| Ok(snippet) if snippet.starts_with('*') => { |
| let sp = span.with_lo(span.lo() + BytePos(1)); |
| let inner = self.find_expr(sp); |
| let mut is_raw_ptr = false; |
| if let Some(inner) = inner { |
| let typck_result = self.infcx.tcx.typeck(self.mir_def_id()); |
| if let Some(inner_type) = typck_result.node_type_opt(inner.hir_id) { |
| if matches!(inner_type.kind(), ty::RawPtr(..)) { |
| is_raw_ptr = true; |
| } |
| } |
| } |
| // If the `inner` is a raw pointer, do not suggest removing the "*", see #126863 |
| // FIXME: need to check whether the assigned object can be a raw pointer, see `tests/ui/borrowck/issue-20801.rs`. |
| if !is_raw_ptr { |
| err.span_suggestion_verbose( |
| span.with_hi(span.lo() + BytePos(1)), |
| "consider removing the dereference here", |
| String::new(), |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| _ => { |
| err.span_suggestion_verbose( |
| span.shrink_to_lo(), |
| "consider borrowing here", |
| '&', |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| } |
| |
| fn add_move_error_suggestions(&self, err: &mut Diag<'_>, binds_to: &[Local]) { |
| /// A HIR visitor to associate each binding with a `&` or `&mut` that could be removed to |
| /// make it bind by reference instead (if possible) |
| struct BindingFinder<'tcx> { |
| typeck_results: &'tcx ty::TypeckResults<'tcx>, |
| tcx: TyCtxt<'tcx>, |
| /// Input: the span of the pattern we're finding bindings in |
| pat_span: Span, |
| /// Input: the spans of the bindings we're providing suggestions for |
| binding_spans: Vec<Span>, |
| /// Internal state: have we reached the pattern we're finding bindings in? |
| found_pat: bool, |
| /// Internal state: the innermost `&` or `&mut` "above" the visitor |
| ref_pat: Option<&'tcx hir::Pat<'tcx>>, |
| /// Internal state: could removing a `&` give bindings unexpected types? |
| has_adjustments: bool, |
| /// Output: for each input binding, the `&` or `&mut` to remove to make it by-ref |
| ref_pat_for_binding: Vec<(Span, Option<&'tcx hir::Pat<'tcx>>)>, |
| /// Output: ref patterns that can't be removed straightforwardly |
| cannot_remove: FxHashSet<HirId>, |
| } |
| impl<'tcx> Visitor<'tcx> for BindingFinder<'tcx> { |
| type NestedFilter = rustc_middle::hir::nested_filter::OnlyBodies; |
| |
| fn maybe_tcx(&mut self) -> Self::MaybeTyCtxt { |
| self.tcx |
| } |
| |
| fn visit_expr(&mut self, ex: &'tcx hir::Expr<'tcx>) -> Self::Result { |
| // Don't walk into const patterns or anything else that might confuse this |
| if !self.found_pat { |
| hir::intravisit::walk_expr(self, ex) |
| } |
| } |
| |
| fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) { |
| if p.span == self.pat_span { |
| self.found_pat = true; |
| } |
| |
| let parent_has_adjustments = self.has_adjustments; |
| self.has_adjustments |= |
| self.typeck_results.pat_adjustments().contains_key(p.hir_id); |
| |
| // Track the innermost `&` or `&mut` enclosing bindings, to suggest removing it. |
| let parent_ref_pat = self.ref_pat; |
| if let hir::PatKind::Ref(..) = p.kind { |
| self.ref_pat = Some(p); |
| // To avoid edition-dependent logic to figure out how many refs this `&` can |
| // peel off, simply don't remove the "parent" `&`. |
| self.cannot_remove.extend(parent_ref_pat.map(|r| r.hir_id)); |
| if self.has_adjustments { |
| // Removing this `&` could give child bindings unexpected types, so don't. |
| self.cannot_remove.insert(p.hir_id); |
| // As long the `&` stays, child patterns' types should be as expected. |
| self.has_adjustments = false; |
| } |
| } |
| |
| if let hir::PatKind::Binding(_, _, ident, _) = p.kind { |
| // the spans in `binding_spans` encompass both the ident and binding mode |
| if let Some(&bind_sp) = |
| self.binding_spans.iter().find(|bind_sp| bind_sp.contains(ident.span)) |
| { |
| self.ref_pat_for_binding.push((bind_sp, self.ref_pat)); |
| } else { |
| // we've encountered a binding that we're not reporting a move error for. |
| // we don't want to change its type, so don't remove the surrounding `&`. |
| if let Some(ref_pat) = self.ref_pat { |
| self.cannot_remove.insert(ref_pat.hir_id); |
| } |
| } |
| } |
| |
| hir::intravisit::walk_pat(self, p); |
| self.ref_pat = parent_ref_pat; |
| self.has_adjustments = parent_has_adjustments; |
| } |
| } |
| let mut pat_span = None; |
| let mut binding_spans = Vec::new(); |
| for local in binds_to { |
| let bind_to = &self.body.local_decls[*local]; |
| if let LocalInfo::User(BindingForm::Var(VarBindingForm { pat_span: pat_sp, .. })) = |
| *bind_to.local_info() |
| { |
| pat_span = Some(pat_sp); |
| binding_spans.push(bind_to.source_info.span); |
| } |
| } |
| let Some(pat_span) = pat_span else { return }; |
| |
| let tcx = self.infcx.tcx; |
| let Some(body) = tcx.hir_maybe_body_owned_by(self.mir_def_id()) else { return }; |
| let typeck_results = self.infcx.tcx.typeck(self.mir_def_id()); |
| let mut finder = BindingFinder { |
| typeck_results, |
| tcx, |
| pat_span, |
| binding_spans, |
| found_pat: false, |
| ref_pat: None, |
| has_adjustments: false, |
| ref_pat_for_binding: Vec::new(), |
| cannot_remove: FxHashSet::default(), |
| }; |
| finder.visit_body(body); |
| |
| let mut suggestions = Vec::new(); |
| for (binding_span, opt_ref_pat) in finder.ref_pat_for_binding { |
| if let Some(ref_pat) = opt_ref_pat |
| && !finder.cannot_remove.contains(&ref_pat.hir_id) |
| && let hir::PatKind::Ref(subpat, mutbl) = ref_pat.kind |
| && let Some(ref_span) = ref_pat.span.trim_end(subpat.span) |
| { |
| let mutable_str = if mutbl.is_mut() { "mutable " } else { "" }; |
| let msg = format!("consider removing the {mutable_str}borrow"); |
| suggestions.push((ref_span, msg, "".to_string())); |
| } else { |
| let msg = "consider borrowing the pattern binding".to_string(); |
| suggestions.push((binding_span.shrink_to_lo(), msg, "ref ".to_string())); |
| } |
| } |
| suggestions.sort_unstable_by_key(|&(span, _, _)| span); |
| suggestions.dedup_by_key(|&mut (span, _, _)| span); |
| for (span, msg, suggestion) in suggestions { |
| err.span_suggestion_verbose(span, msg, suggestion, Applicability::MachineApplicable); |
| } |
| } |
| |
| fn add_move_error_details(&self, err: &mut Diag<'_>, binds_to: &[Local]) { |
| for (j, local) in binds_to.iter().enumerate() { |
| let bind_to = &self.body.local_decls[*local]; |
| let binding_span = bind_to.source_info.span; |
| |
| if j == 0 { |
| err.span_label(binding_span, "data moved here"); |
| } else { |
| err.span_label(binding_span, "...and here"); |
| } |
| |
| if binds_to.len() == 1 { |
| let place_desc = self.local_name(*local).map(|sym| format!("`{sym}`")); |
| |
| if let Some(expr) = self.find_expr(binding_span) { |
| let local_place: PlaceRef<'tcx> = (*local).into(); |
| self.suggest_cloning(err, local_place, bind_to.ty, expr, None); |
| } |
| |
| err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label { |
| is_partial_move: false, |
| ty: bind_to.ty, |
| place: place_desc.as_deref().unwrap_or("the place"), |
| span: binding_span, |
| }); |
| } |
| } |
| |
| if binds_to.len() > 1 { |
| err.note( |
| "move occurs because these variables have types that don't implement the `Copy` \ |
| trait", |
| ); |
| } |
| } |
| |
| /// Adds an explanatory note if the move error occurs in a derive macro |
| /// expansion of a packed struct. |
| /// Such errors happen because derive macro expansions shy away from taking |
| /// references to the struct's fields since doing so would be undefined behaviour |
| fn add_note_for_packed_struct_derive(&self, err: &mut Diag<'_>, local: Local) { |
| let local_place: PlaceRef<'tcx> = local.into(); |
| let local_ty = local_place.ty(self.body.local_decls(), self.infcx.tcx).ty.peel_refs(); |
| |
| if let Some(adt) = local_ty.ty_adt_def() |
| && adt.repr().packed() |
| && let ExpnKind::Macro(MacroKind::Derive, name) = |
| self.body.span.ctxt().outer_expn_data().kind |
| { |
| err.note(format!("`#[derive({name})]` triggers a move because taking references to the fields of a packed struct is undefined behaviour")); |
| } |
| } |
| } |
