| //! Borrow checker diagnostics. |
| |
| use rustc::hir; |
| use rustc::hir::def::Namespace; |
| use rustc::hir::def_id::DefId; |
| use rustc::hir::GeneratorKind; |
| use rustc::mir::{ |
| AggregateKind, Constant, Field, Local, LocalInfo, LocalKind, Location, Operand, |
| Place, PlaceBase, PlaceRef, ProjectionElem, Rvalue, Statement, StatementKind, |
| Static, StaticKind, Terminator, TerminatorKind, |
| }; |
| use rustc::ty::{self, DefIdTree, Ty, TyCtxt}; |
| use rustc::ty::layout::VariantIdx; |
| use rustc::ty::print::Print; |
| use rustc_errors::DiagnosticBuilder; |
| use syntax_pos::Span; |
| |
| use super::borrow_set::BorrowData; |
| use super::MirBorrowckCtxt; |
| use crate::dataflow::move_paths::{InitLocation, LookupResult}; |
| |
| mod find_use; |
| mod var_name; |
| mod region_name; |
| mod outlives_suggestion; |
| |
| mod conflict_errors; |
| mod move_errors; |
| mod mutability_errors; |
| mod region_errors; |
| mod explain_borrow; |
| |
| crate use mutability_errors::AccessKind; |
| crate use region_name::{RegionName, RegionNameSource, RegionErrorNamingCtx}; |
| crate use region_errors::{ErrorReportingCtx, ErrorConstraintInfo}; |
| crate use outlives_suggestion::OutlivesSuggestionBuilder; |
| |
| pub(super) struct IncludingDowncast(pub(super) bool); |
| |
| impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { |
| /// Adds a suggestion when a closure is invoked twice with a moved variable or when a closure |
| /// is moved after being invoked. |
| /// |
| /// ```text |
| /// note: closure cannot be invoked more than once because it moves the variable `dict` out of |
| /// its environment |
| /// --> $DIR/issue-42065.rs:16:29 |
| /// | |
| /// LL | for (key, value) in dict { |
| /// | ^^^^ |
| /// ``` |
| pub(super) fn add_moved_or_invoked_closure_note( |
| &self, |
| location: Location, |
| place: PlaceRef<'cx, 'tcx>, |
| diag: &mut DiagnosticBuilder<'_>, |
| ) { |
| debug!("add_moved_or_invoked_closure_note: location={:?} place={:?}", location, place); |
| let mut target = place.local_or_deref_local(); |
| for stmt in &self.body[location.block].statements[location.statement_index..] { |
| debug!("add_moved_or_invoked_closure_note: stmt={:?} target={:?}", stmt, target); |
| if let StatementKind::Assign(box(into, Rvalue::Use(from))) = &stmt.kind { |
| debug!("add_fnonce_closure_note: into={:?} from={:?}", into, from); |
| match from { |
| Operand::Copy(ref place) | |
| Operand::Move(ref place) if target == place.local_or_deref_local() => |
| target = into.local_or_deref_local(), |
| _ => {}, |
| } |
| } |
| } |
| |
| // Check if we are attempting to call a closure after it has been invoked. |
| let terminator = self.body[location.block].terminator(); |
| debug!("add_moved_or_invoked_closure_note: terminator={:?}", terminator); |
| if let TerminatorKind::Call { |
| func: Operand::Constant(box Constant { |
| literal: ty::Const { |
| ty: &ty::TyS { kind: ty::FnDef(id, _), .. }, |
| .. |
| }, |
| .. |
| }), |
| args, |
| .. |
| } = &terminator.kind { |
| debug!("add_moved_or_invoked_closure_note: id={:?}", id); |
| if self.infcx.tcx.parent(id) == self.infcx.tcx.lang_items().fn_once_trait() { |
| let closure = match args.first() { |
| Some(Operand::Copy(ref place)) | |
| Some(Operand::Move(ref place)) if target == place.local_or_deref_local() => |
| place.local_or_deref_local().unwrap(), |
| _ => return, |
| }; |
| |
| debug!("add_moved_or_invoked_closure_note: closure={:?}", closure); |
| if let ty::Closure(did, _) = self.body.local_decls[closure].ty.kind { |
| let hir_id = self.infcx.tcx.hir().as_local_hir_id(did).unwrap(); |
| |
| if let Some((span, name)) = self.infcx.tcx.typeck_tables_of(did) |
| .closure_kind_origins() |
| .get(hir_id) |
| { |
| diag.span_note( |
| *span, |
| &format!( |
| "closure cannot be invoked more than once because it moves the \ |
| variable `{}` out of its environment", |
| name, |
| ), |
| ); |
| return; |
| } |
| } |
| } |
| } |
| |
| // Check if we are just moving a closure after it has been invoked. |
| if let Some(target) = target { |
| if let ty::Closure(did, _) = self.body.local_decls[target].ty.kind { |
| let hir_id = self.infcx.tcx.hir().as_local_hir_id(did).unwrap(); |
| |
| if let Some((span, name)) = self.infcx.tcx.typeck_tables_of(did) |
| .closure_kind_origins() |
| .get(hir_id) |
| { |
| diag.span_note( |
| *span, |
| &format!( |
| "closure cannot be moved more than once as it is not `Copy` due to \ |
| moving the variable `{}` out of its environment", |
| name |
| ), |
| ); |
| } |
| } |
| } |
| } |
| |
| /// End-user visible description of `place` if one can be found. If the |
| /// place is a temporary for instance, None will be returned. |
| pub(super) fn describe_place(&self, place_ref: PlaceRef<'cx, 'tcx>) -> Option<String> { |
| self.describe_place_with_options(place_ref, IncludingDowncast(false)) |
| } |
| |
| /// End-user visible description of `place` if one can be found. If the |
| /// place is a temporary for instance, None will be returned. |
| /// `IncludingDowncast` parameter makes the function return `Err` if `ProjectionElem` is |
| /// `Downcast` and `IncludingDowncast` is true |
| pub(super) fn describe_place_with_options( |
| &self, |
| place: PlaceRef<'cx, 'tcx>, |
| including_downcast: IncludingDowncast, |
| ) -> Option<String> { |
| let mut buf = String::new(); |
| match self.append_place_to_string(place, &mut buf, false, &including_downcast) { |
| Ok(()) => Some(buf), |
| Err(()) => None, |
| } |
| } |
| |
| /// Appends end-user visible description of `place` to `buf`. |
| fn append_place_to_string( |
| &self, |
| place: PlaceRef<'cx, 'tcx>, |
| buf: &mut String, |
| mut autoderef: bool, |
| including_downcast: &IncludingDowncast, |
| ) -> Result<(), ()> { |
| match place { |
| PlaceRef { |
| base: PlaceBase::Local(local), |
| projection: [], |
| } => { |
| self.append_local_to_string(*local, buf)?; |
| } |
| PlaceRef { |
| base: |
| PlaceBase::Static(box Static { |
| kind: StaticKind::Promoted(..), |
| .. |
| }), |
| projection: [], |
| } => { |
| buf.push_str("promoted"); |
| } |
| PlaceRef { |
| base: |
| PlaceBase::Static(box Static { |
| kind: StaticKind::Static, |
| def_id, |
| .. |
| }), |
| projection: [], |
| } => { |
| buf.push_str(&self.infcx.tcx.item_name(*def_id).to_string()); |
| } |
| PlaceRef { |
| base: &PlaceBase::Local(local), |
| projection: [ProjectionElem::Deref] |
| } if self.body.local_decls[local].is_ref_for_guard() => { |
| self.append_place_to_string( |
| PlaceRef { |
| base: &PlaceBase::Local(local), |
| projection: &[], |
| }, |
| buf, |
| autoderef, |
| &including_downcast, |
| )?; |
| }, |
| PlaceRef { |
| base: &PlaceBase::Local(local), |
| projection: [ProjectionElem::Deref] |
| } if self.body.local_decls[local].is_ref_to_static() => { |
| let local_info = &self.body.local_decls[local].local_info; |
| if let LocalInfo::StaticRef { def_id, .. } = *local_info { |
| buf.push_str(&self.infcx.tcx.item_name(def_id).as_str()); |
| } else { |
| unreachable!(); |
| } |
| }, |
| PlaceRef { |
| base, |
| projection: [proj_base @ .., elem], |
| } => { |
| match elem { |
| ProjectionElem::Deref => { |
| let upvar_field_projection = |
| self.is_upvar_field_projection(place); |
| if let Some(field) = upvar_field_projection { |
| let var_index = field.index(); |
| let name = self.upvars[var_index].name.to_string(); |
| if self.upvars[var_index].by_ref { |
| buf.push_str(&name); |
| } else { |
| buf.push_str(&format!("*{}", &name)); |
| } |
| } else { |
| if autoderef { |
| // FIXME turn this recursion into iteration |
| self.append_place_to_string( |
| PlaceRef { |
| base, |
| projection: proj_base, |
| }, |
| buf, |
| autoderef, |
| &including_downcast, |
| )?; |
| } else { |
| match (proj_base, base) { |
| _ => { |
| buf.push_str(&"*"); |
| self.append_place_to_string( |
| PlaceRef { |
| base, |
| projection: proj_base, |
| }, |
| buf, |
| autoderef, |
| &including_downcast, |
| )?; |
| } |
| } |
| } |
| } |
| } |
| ProjectionElem::Downcast(..) => { |
| self.append_place_to_string( |
| PlaceRef { |
| base, |
| projection: proj_base, |
| }, |
| buf, |
| autoderef, |
| &including_downcast, |
| )?; |
| if including_downcast.0 { |
| return Err(()); |
| } |
| } |
| ProjectionElem::Field(field, _ty) => { |
| autoderef = true; |
| |
| let upvar_field_projection = |
| self.is_upvar_field_projection(place); |
| if let Some(field) = upvar_field_projection { |
| let var_index = field.index(); |
| let name = self.upvars[var_index].name.to_string(); |
| buf.push_str(&name); |
| } else { |
| let field_name = self.describe_field(PlaceRef { |
| base, |
| projection: proj_base, |
| }, *field); |
| self.append_place_to_string( |
| PlaceRef { |
| base, |
| projection: proj_base, |
| }, |
| buf, |
| autoderef, |
| &including_downcast, |
| )?; |
| buf.push_str(&format!(".{}", field_name)); |
| } |
| } |
| ProjectionElem::Index(index) => { |
| autoderef = true; |
| |
| self.append_place_to_string( |
| PlaceRef { |
| base, |
| projection: proj_base, |
| }, |
| buf, |
| autoderef, |
| &including_downcast, |
| )?; |
| buf.push_str("["); |
| if self.append_local_to_string(*index, buf).is_err() { |
| buf.push_str("_"); |
| } |
| buf.push_str("]"); |
| } |
| ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => { |
| autoderef = true; |
| // Since it isn't possible to borrow an element on a particular index and |
| // then use another while the borrow is held, don't output indices details |
| // to avoid confusing the end-user |
| self.append_place_to_string( |
| PlaceRef { |
| base, |
| projection: proj_base, |
| }, |
| buf, |
| autoderef, |
| &including_downcast, |
| )?; |
| buf.push_str(&"[..]"); |
| } |
| }; |
| } |
| } |
| |
| Ok(()) |
| } |
| |
| /// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have |
| /// a name, or its name was generated by the compiler, then `Err` is returned |
| fn append_local_to_string(&self, local: Local, buf: &mut String) -> Result<(), ()> { |
| let decl = &self.body.local_decls[local]; |
| match self.local_names[local] { |
| Some(name) if !decl.from_compiler_desugaring() => { |
| buf.push_str(&name.as_str()); |
| Ok(()) |
| } |
| _ => Err(()), |
| } |
| } |
| |
| /// End-user visible description of the `field`nth field of `base` |
| fn describe_field(&self, place: PlaceRef<'cx, 'tcx>, field: Field) -> String { |
| // FIXME Place2 Make this work iteratively |
| match place { |
| PlaceRef { |
| base: PlaceBase::Local(local), |
| projection: [], |
| } => { |
| let local = &self.body.local_decls[*local]; |
| self.describe_field_from_ty(&local.ty, field, None) |
| } |
| PlaceRef { |
| base: PlaceBase::Static(static_), |
| projection: [], |
| } => |
| self.describe_field_from_ty(&static_.ty, field, None), |
| PlaceRef { |
| base, |
| projection: [proj_base @ .., elem], |
| } => match elem { |
| ProjectionElem::Deref => { |
| self.describe_field(PlaceRef { |
| base, |
| projection: proj_base, |
| }, field) |
| } |
| ProjectionElem::Downcast(_, variant_index) => { |
| let base_ty = Place::ty_from( |
| place.base, |
| place.projection, |
| *self.body, |
| self.infcx.tcx).ty; |
| self.describe_field_from_ty(&base_ty, field, Some(*variant_index)) |
| } |
| ProjectionElem::Field(_, field_type) => { |
| self.describe_field_from_ty(&field_type, field, None) |
| } |
| ProjectionElem::Index(..) |
| | ProjectionElem::ConstantIndex { .. } |
| | ProjectionElem::Subslice { .. } => { |
| self.describe_field(PlaceRef { |
| base, |
| projection: proj_base, |
| }, field) |
| } |
| }, |
| } |
| } |
| |
| /// End-user visible description of the `field_index`nth field of `ty` |
| fn describe_field_from_ty( |
| &self, |
| ty: Ty<'_>, |
| field: Field, |
| variant_index: Option<VariantIdx> |
| ) -> String { |
| if ty.is_box() { |
| // If the type is a box, the field is described from the boxed type |
| self.describe_field_from_ty(&ty.boxed_ty(), field, variant_index) |
| } else { |
| match ty.kind { |
| ty::Adt(def, _) => { |
| let variant = if let Some(idx) = variant_index { |
| assert!(def.is_enum()); |
| &def.variants[idx] |
| } else { |
| def.non_enum_variant() |
| }; |
| variant.fields[field.index()] |
| .ident |
| .to_string() |
| }, |
| ty::Tuple(_) => field.index().to_string(), |
| ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => { |
| self.describe_field_from_ty(&ty, field, variant_index) |
| } |
| ty::Array(ty, _) | ty::Slice(ty) => |
| self.describe_field_from_ty(&ty, field, variant_index), |
| ty::Closure(def_id, _) | ty::Generator(def_id, _, _) => { |
| // `tcx.upvars(def_id)` returns an `Option`, which is `None` in case |
| // the closure comes from another crate. But in that case we wouldn't |
| // be borrowck'ing it, so we can just unwrap: |
| let (&var_id, _) = self.infcx.tcx.upvars(def_id).unwrap() |
| .get_index(field.index()).unwrap(); |
| |
| self.infcx.tcx.hir().name(var_id).to_string() |
| } |
| _ => { |
| // Might need a revision when the fields in trait RFC is implemented |
| // (https://github.com/rust-lang/rfcs/pull/1546) |
| bug!( |
| "End-user description not implemented for field access on `{:?}`", |
| ty |
| ); |
| } |
| } |
| } |
| } |
| |
| /// Add a note that a type does not implement `Copy` |
| pub(super) fn note_type_does_not_implement_copy( |
| &self, |
| err: &mut DiagnosticBuilder<'a>, |
| place_desc: &str, |
| ty: Ty<'tcx>, |
| span: Option<Span>, |
| ) { |
| let message = format!( |
| "move occurs because {} has type `{}`, which does not implement the `Copy` trait", |
| place_desc, |
| ty, |
| ); |
| if let Some(span) = span { |
| err.span_label(span, message); |
| } else { |
| err.note(&message); |
| } |
| } |
| |
| pub(super) fn borrowed_content_source( |
| &self, |
| deref_base: PlaceRef<'cx, 'tcx>, |
| ) -> BorrowedContentSource<'tcx> { |
| let tcx = self.infcx.tcx; |
| |
| // Look up the provided place and work out the move path index for it, |
| // we'll use this to check whether it was originally from an overloaded |
| // operator. |
| match self.move_data.rev_lookup.find(deref_base) { |
| LookupResult::Exact(mpi) | LookupResult::Parent(Some(mpi)) => { |
| debug!("borrowed_content_source: mpi={:?}", mpi); |
| |
| for i in &self.move_data.init_path_map[mpi] { |
| let init = &self.move_data.inits[*i]; |
| debug!("borrowed_content_source: init={:?}", init); |
| // We're only interested in statements that initialized a value, not the |
| // initializations from arguments. |
| let loc = match init.location { |
| InitLocation::Statement(stmt) => stmt, |
| _ => continue, |
| }; |
| |
| let bbd = &self.body[loc.block]; |
| let is_terminator = bbd.statements.len() == loc.statement_index; |
| debug!( |
| "borrowed_content_source: loc={:?} is_terminator={:?}", |
| loc, |
| is_terminator, |
| ); |
| if !is_terminator { |
| continue; |
| } else if let Some(Terminator { |
| kind: TerminatorKind::Call { |
| ref func, |
| from_hir_call: false, |
| .. |
| }, |
| .. |
| }) = bbd.terminator { |
| if let Some(source) = BorrowedContentSource::from_call( |
| func.ty(*self.body, tcx), |
| tcx |
| ) { |
| return source; |
| } |
| } |
| } |
| } |
| // Base is a `static` so won't be from an overloaded operator |
| _ => (), |
| }; |
| |
| // If we didn't find an overloaded deref or index, then assume it's a |
| // built in deref and check the type of the base. |
| let base_ty = Place::ty_from( |
| deref_base.base, |
| deref_base.projection, |
| *self.body, |
| tcx |
| ).ty; |
| if base_ty.is_unsafe_ptr() { |
| BorrowedContentSource::DerefRawPointer |
| } else if base_ty.is_mutable_ptr() { |
| BorrowedContentSource::DerefMutableRef |
| } else { |
| BorrowedContentSource::DerefSharedRef |
| } |
| } |
| } |
| |
| impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { |
| /// Return the name of the provided `Ty` (that must be a reference) with a synthesized lifetime |
| /// name where required. |
| pub(super) fn get_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String { |
| let mut s = String::new(); |
| let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, &mut s, Namespace::TypeNS); |
| |
| // We need to add synthesized lifetimes where appropriate. We do |
| // this by hooking into the pretty printer and telling it to label the |
| // lifetimes without names with the value `'0`. |
| match ty.kind { |
| ty::Ref(ty::RegionKind::ReLateBound(_, br), _, _) |
| | ty::Ref( |
| ty::RegionKind::RePlaceholder(ty::PlaceholderRegion { name: br, .. }), |
| _, |
| _, |
| ) => printer.region_highlight_mode.highlighting_bound_region(*br, counter), |
| _ => {} |
| } |
| |
| let _ = ty.print(printer); |
| s |
| } |
| |
| /// Returns the name of the provided `Ty` (that must be a reference)'s region with a |
| /// synthesized lifetime name where required. |
| pub(super) fn get_region_name_for_ty(&self, ty: Ty<'tcx>, counter: usize) -> String { |
| let mut s = String::new(); |
| let mut printer = ty::print::FmtPrinter::new(self.infcx.tcx, &mut s, Namespace::TypeNS); |
| |
| let region = match ty.kind { |
| ty::Ref(region, _, _) => { |
| match region { |
| ty::RegionKind::ReLateBound(_, br) |
| | ty::RegionKind::RePlaceholder(ty::PlaceholderRegion { name: br, .. }) => { |
| printer.region_highlight_mode.highlighting_bound_region(*br, counter) |
| } |
| _ => {} |
| } |
| |
| region |
| } |
| _ => bug!("ty for annotation of borrow region is not a reference"), |
| }; |
| |
| let _ = region.print(printer); |
| s |
| } |
| } |
| |
| // The span(s) associated to a use of a place. |
| #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
| pub(super) enum UseSpans { |
| // The access is caused by capturing a variable for a closure. |
| ClosureUse { |
| // This is true if the captured variable was from a generator. |
| generator_kind: Option<GeneratorKind>, |
| // The span of the args of the closure, including the `move` keyword if |
| // it's present. |
| args_span: Span, |
| // The span of the first use of the captured variable inside the closure. |
| var_span: Span, |
| }, |
| // This access has a single span associated to it: common case. |
| OtherUse(Span), |
| } |
| |
| impl UseSpans { |
| pub(super) fn args_or_use(self) -> Span { |
| match self { |
| UseSpans::ClosureUse { |
| args_span: span, .. |
| } |
| | UseSpans::OtherUse(span) => span, |
| } |
| } |
| |
| pub(super) fn var_or_use(self) -> Span { |
| match self { |
| UseSpans::ClosureUse { var_span: span, .. } | UseSpans::OtherUse(span) => span, |
| } |
| } |
| |
| pub(super) fn generator_kind(self) -> Option<GeneratorKind> { |
| match self { |
| UseSpans::ClosureUse { generator_kind, .. } => generator_kind, |
| _ => None, |
| } |
| } |
| |
| // Add a span label to the arguments of the closure, if it exists. |
| pub(super) fn args_span_label( |
| self, |
| err: &mut DiagnosticBuilder<'_>, |
| message: impl Into<String>, |
| ) { |
| if let UseSpans::ClosureUse { args_span, .. } = self { |
| err.span_label(args_span, message); |
| } |
| } |
| |
| // Add a span label to the use of the captured variable, if it exists. |
| pub(super) fn var_span_label( |
| self, |
| err: &mut DiagnosticBuilder<'_>, |
| message: impl Into<String>, |
| ) { |
| if let UseSpans::ClosureUse { var_span, .. } = self { |
| err.span_label(var_span, message); |
| } |
| } |
| |
| /// Returns `false` if this place is not used in a closure. |
| pub(super) fn for_closure(&self) -> bool { |
| match *self { |
| UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_none(), |
| _ => false, |
| } |
| } |
| |
| /// Returns `false` if this place is not used in a generator. |
| pub(super) fn for_generator(&self) -> bool { |
| match *self { |
| UseSpans::ClosureUse { generator_kind, .. } => generator_kind.is_some(), |
| _ => false, |
| } |
| } |
| |
| /// Describe the span associated with a use of a place. |
| pub(super) fn describe(&self) -> String { |
| match *self { |
| UseSpans::ClosureUse { generator_kind, .. } => if generator_kind.is_some() { |
| " in generator".to_string() |
| } else { |
| " in closure".to_string() |
| }, |
| _ => "".to_string(), |
| } |
| } |
| |
| pub(super) fn or_else<F>(self, if_other: F) -> Self |
| where |
| F: FnOnce() -> Self, |
| { |
| match self { |
| closure @ UseSpans::ClosureUse { .. } => closure, |
| UseSpans::OtherUse(_) => if_other(), |
| } |
| } |
| } |
| |
| pub(super) enum BorrowedContentSource<'tcx> { |
| DerefRawPointer, |
| DerefMutableRef, |
| DerefSharedRef, |
| OverloadedDeref(Ty<'tcx>), |
| OverloadedIndex(Ty<'tcx>), |
| } |
| |
| impl BorrowedContentSource<'tcx> { |
| pub(super) fn describe_for_unnamed_place(&self) -> String { |
| match *self { |
| BorrowedContentSource::DerefRawPointer => format!("a raw pointer"), |
| BorrowedContentSource::DerefSharedRef => format!("a shared reference"), |
| BorrowedContentSource::DerefMutableRef => { |
| format!("a mutable reference") |
| } |
| BorrowedContentSource::OverloadedDeref(ty) => { |
| if ty.is_rc() { |
| format!("an `Rc`") |
| } else if ty.is_arc() { |
| format!("an `Arc`") |
| } else { |
| format!("dereference of `{}`", ty) |
| } |
| } |
| BorrowedContentSource::OverloadedIndex(ty) => format!("index of `{}`", ty), |
| } |
| } |
| |
| pub(super) fn describe_for_named_place(&self) -> Option<&'static str> { |
| match *self { |
| BorrowedContentSource::DerefRawPointer => Some("raw pointer"), |
| BorrowedContentSource::DerefSharedRef => Some("shared reference"), |
| BorrowedContentSource::DerefMutableRef => Some("mutable reference"), |
| // Overloaded deref and index operators should be evaluated into a |
| // temporary. So we don't need a description here. |
| BorrowedContentSource::OverloadedDeref(_) |
| | BorrowedContentSource::OverloadedIndex(_) => None |
| } |
| } |
| |
| pub(super) fn describe_for_immutable_place(&self) -> String { |
| match *self { |
| BorrowedContentSource::DerefRawPointer => format!("a `*const` pointer"), |
| BorrowedContentSource::DerefSharedRef => format!("a `&` reference"), |
| BorrowedContentSource::DerefMutableRef => { |
| bug!("describe_for_immutable_place: DerefMutableRef isn't immutable") |
| }, |
| BorrowedContentSource::OverloadedDeref(ty) => { |
| if ty.is_rc() { |
| format!("an `Rc`") |
| } else if ty.is_arc() { |
| format!("an `Arc`") |
| } else { |
| format!("a dereference of `{}`", ty) |
| } |
| } |
| BorrowedContentSource::OverloadedIndex(ty) => format!("an index of `{}`", ty), |
| } |
| } |
| |
| fn from_call(func: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Self> { |
| match func.kind { |
| ty::FnDef(def_id, substs) => { |
| let trait_id = tcx.trait_of_item(def_id)?; |
| |
| let lang_items = tcx.lang_items(); |
| if Some(trait_id) == lang_items.deref_trait() |
| || Some(trait_id) == lang_items.deref_mut_trait() |
| { |
| Some(BorrowedContentSource::OverloadedDeref(substs.type_at(0))) |
| } else if Some(trait_id) == lang_items.index_trait() |
| || Some(trait_id) == lang_items.index_mut_trait() |
| { |
| Some(BorrowedContentSource::OverloadedIndex(substs.type_at(0))) |
| } else { |
| None |
| } |
| } |
| _ => None, |
| } |
| } |
| } |
| |
| impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { |
| /// Finds the spans associated to a move or copy of move_place at location. |
| pub(super) fn move_spans( |
| &self, |
| moved_place: PlaceRef<'cx, 'tcx>, // Could also be an upvar. |
| location: Location, |
| ) -> UseSpans { |
| use self::UseSpans::*; |
| |
| let stmt = match self.body[location.block].statements.get(location.statement_index) { |
| Some(stmt) => stmt, |
| None => return OtherUse(self.body.source_info(location).span), |
| }; |
| |
| debug!("move_spans: moved_place={:?} location={:?} stmt={:?}", moved_place, location, stmt); |
| if let StatementKind::Assign( |
| box(_, Rvalue::Aggregate(ref kind, ref places)) |
| ) = stmt.kind { |
| let def_id = match kind { |
| box AggregateKind::Closure(def_id, _) |
| | box AggregateKind::Generator(def_id, _, _) => def_id, |
| _ => return OtherUse(stmt.source_info.span), |
| }; |
| |
| debug!( |
| "move_spans: def_id={:?} places={:?}", |
| def_id, places |
| ); |
| if let Some((args_span, generator_kind, var_span)) |
| = self.closure_span(*def_id, moved_place, places) { |
| return ClosureUse { |
| generator_kind, |
| args_span, |
| var_span, |
| }; |
| } |
| } |
| |
| OtherUse(stmt.source_info.span) |
| } |
| |
| /// Finds the span of arguments of a closure (within `maybe_closure_span`) |
| /// and its usage of the local assigned at `location`. |
| /// This is done by searching in statements succeeding `location` |
| /// and originating from `maybe_closure_span`. |
| pub(super) fn borrow_spans(&self, use_span: Span, location: Location) -> UseSpans { |
| use self::UseSpans::*; |
| debug!("borrow_spans: use_span={:?} location={:?}", use_span, location); |
| |
| let target = match self.body[location.block] |
| .statements |
| .get(location.statement_index) |
| { |
| Some(&Statement { |
| kind: StatementKind::Assign(box(ref place, _)), |
| .. |
| }) => { |
| if let Some(local) = place.as_local() { |
| local |
| } else { |
| return OtherUse(use_span); |
| } |
| } |
| _ => return OtherUse(use_span), |
| }; |
| |
| if self.body.local_kind(target) != LocalKind::Temp { |
| // operands are always temporaries. |
| return OtherUse(use_span); |
| } |
| |
| for stmt in &self.body[location.block].statements[location.statement_index + 1..] { |
| if let StatementKind::Assign( |
| box(_, Rvalue::Aggregate(ref kind, ref places)) |
| ) = stmt.kind { |
| let (def_id, is_generator) = match kind { |
| box AggregateKind::Closure(def_id, _) => (def_id, false), |
| box AggregateKind::Generator(def_id, _, _) => (def_id, true), |
| _ => continue, |
| }; |
| |
| debug!( |
| "borrow_spans: def_id={:?} is_generator={:?} places={:?}", |
| def_id, is_generator, places |
| ); |
| if let Some((args_span, generator_kind, var_span)) = self.closure_span( |
| *def_id, Place::from(target).as_ref(), places |
| ) { |
| return ClosureUse { |
| generator_kind, |
| args_span, |
| var_span, |
| }; |
| } else { |
| return OtherUse(use_span); |
| } |
| } |
| |
| if use_span != stmt.source_info.span { |
| break; |
| } |
| } |
| |
| OtherUse(use_span) |
| } |
| |
| /// Finds the span of a captured variable within a closure or generator. |
| fn closure_span( |
| &self, |
| def_id: DefId, |
| target_place: PlaceRef<'cx, 'tcx>, |
| places: &Vec<Operand<'tcx>>, |
| ) -> Option<(Span, Option<GeneratorKind>, Span)> { |
| debug!( |
| "closure_span: def_id={:?} target_place={:?} places={:?}", |
| def_id, target_place, places |
| ); |
| let hir_id = self.infcx.tcx.hir().as_local_hir_id(def_id)?; |
| let expr = &self.infcx.tcx.hir().expect_expr(hir_id).kind; |
| debug!("closure_span: hir_id={:?} expr={:?}", hir_id, expr); |
| if let hir::ExprKind::Closure( |
| .., body_id, args_span, _ |
| ) = expr { |
| for (upvar, place) in self.infcx.tcx.upvars(def_id)?.values().zip(places) { |
| match place { |
| Operand::Copy(place) | |
| Operand::Move(place) if target_place == place.as_ref() => { |
| debug!("closure_span: found captured local {:?}", place); |
| let body = self.infcx.tcx.hir().body(*body_id); |
| let generator_kind = body.generator_kind(); |
| return Some((*args_span, generator_kind, upvar.span)); |
| }, |
| _ => {} |
| } |
| } |
| |
| } |
| None |
| } |
| |
| /// Helper to retrieve span(s) of given borrow from the current MIR |
| /// representation |
| pub(super) fn retrieve_borrow_spans(&self, borrow: &BorrowData<'_>) -> UseSpans { |
| let span = self.body.source_info(borrow.reserve_location).span; |
| self.borrow_spans(span, borrow.reserve_location) |
| } |
| } |
