| use rustc_hir as hir; |
| use rustc_hir::Node; |
| use rustc_middle::hir::map::Map; |
| use rustc_middle::mir::{Mutability, Place, PlaceRef, ProjectionElem}; |
| use rustc_middle::ty::{self, Ty, TyCtxt}; |
| use rustc_middle::{ |
| hir::place::PlaceBase, |
| mir::{ |
| self, BindingForm, ClearCrossCrate, ImplicitSelfKind, Local, LocalDecl, LocalInfo, |
| LocalKind, Location, |
| }, |
| }; |
| use rustc_span::source_map::DesugaringKind; |
| use rustc_span::symbol::{kw, Symbol}; |
| use rustc_span::{BytePos, Span}; |
| |
| use crate::diagnostics::BorrowedContentSource; |
| use crate::MirBorrowckCtxt; |
| use rustc_const_eval::util::collect_writes::FindAssignments; |
| use rustc_errors::{Applicability, DiagnosticBuilder}; |
| |
| #[derive(Copy, Clone, Debug, Eq, PartialEq)] |
| pub(crate) enum AccessKind { |
| MutableBorrow, |
| Mutate, |
| } |
| |
| impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { |
| pub(crate) fn report_mutability_error( |
| &mut self, |
| access_place: Place<'tcx>, |
| span: Span, |
| the_place_err: PlaceRef<'tcx>, |
| error_access: AccessKind, |
| location: Location, |
| ) { |
| debug!( |
| "report_mutability_error(\ |
| access_place={:?}, span={:?}, the_place_err={:?}, error_access={:?}, location={:?},\ |
| )", |
| access_place, span, the_place_err, error_access, location, |
| ); |
| |
| let mut err; |
| let item_msg; |
| let reason; |
| let mut opt_source = None; |
| let access_place_desc = self.describe_place(access_place.as_ref()); |
| debug!("report_mutability_error: access_place_desc={:?}", access_place_desc); |
| |
| match the_place_err { |
| PlaceRef { local, projection: [] } => { |
| item_msg = format!("`{}`", access_place_desc.unwrap()); |
| if access_place.as_local().is_some() { |
| reason = ", as it is not declared as mutable".to_string(); |
| } else { |
| let name = self.local_names[local].expect("immutable unnamed local"); |
| reason = format!(", as `{}` is not declared as mutable", name); |
| } |
| } |
| |
| PlaceRef { |
| local, |
| projection: [proj_base @ .., ProjectionElem::Field(upvar_index, _)], |
| } => { |
| debug_assert!(is_closure_or_generator( |
| Place::ty_from(local, proj_base, self.body, self.infcx.tcx).ty |
| )); |
| |
| let imm_borrow_derefed = self.upvars[upvar_index.index()] |
| .place |
| .place |
| .deref_tys() |
| .any(|ty| matches!(ty.kind(), ty::Ref(.., hir::Mutability::Not))); |
| |
| // If the place is immutable then: |
| // |
| // - Either we deref an immutable ref to get to our final place. |
| // - We don't capture derefs of raw ptrs |
| // - Or the final place is immut because the root variable of the capture |
| // isn't marked mut and we should suggest that to the user. |
| if imm_borrow_derefed { |
| // If we deref an immutable ref then the suggestion here doesn't help. |
| return; |
| } else { |
| item_msg = format!("`{}`", access_place_desc.unwrap()); |
| if self.is_upvar_field_projection(access_place.as_ref()).is_some() { |
| reason = ", as it is not declared as mutable".to_string(); |
| } else { |
| let name = self.upvars[upvar_index.index()].place.to_string(self.infcx.tcx); |
| reason = format!(", as `{}` is not declared as mutable", name); |
| } |
| } |
| } |
| |
| PlaceRef { local, projection: [ProjectionElem::Deref] } |
| if self.body.local_decls[local].is_ref_for_guard() => |
| { |
| item_msg = format!("`{}`", access_place_desc.unwrap()); |
| reason = ", as it is immutable for the pattern guard".to_string(); |
| } |
| PlaceRef { local, projection: [ProjectionElem::Deref] } |
| if self.body.local_decls[local].is_ref_to_static() => |
| { |
| if access_place.projection.len() == 1 { |
| item_msg = format!("immutable static item `{}`", access_place_desc.unwrap()); |
| reason = String::new(); |
| } else { |
| item_msg = format!("`{}`", access_place_desc.unwrap()); |
| let local_info = &self.body.local_decls[local].local_info; |
| if let Some(box LocalInfo::StaticRef { def_id, .. }) = *local_info { |
| let static_name = &self.infcx.tcx.item_name(def_id); |
| reason = format!(", as `{}` is an immutable static item", static_name); |
| } else { |
| bug!("is_ref_to_static return true, but not ref to static?"); |
| } |
| } |
| } |
| PlaceRef { local: _, projection: [proj_base @ .., ProjectionElem::Deref] } => { |
| if the_place_err.local == ty::CAPTURE_STRUCT_LOCAL |
| && proj_base.is_empty() |
| && !self.upvars.is_empty() |
| { |
| item_msg = format!("`{}`", access_place_desc.unwrap()); |
| debug_assert!( |
| self.body.local_decls[ty::CAPTURE_STRUCT_LOCAL].ty.is_region_ptr() |
| ); |
| debug_assert!(is_closure_or_generator( |
| Place::ty_from( |
| the_place_err.local, |
| the_place_err.projection, |
| self.body, |
| self.infcx.tcx |
| ) |
| .ty |
| )); |
| |
| reason = if self.is_upvar_field_projection(access_place.as_ref()).is_some() { |
| ", as it is a captured variable in a `Fn` closure".to_string() |
| } else { |
| ", as `Fn` closures cannot mutate their captured variables".to_string() |
| } |
| } else { |
| let source = self.borrowed_content_source(PlaceRef { |
| local: the_place_err.local, |
| projection: proj_base, |
| }); |
| let pointer_type = source.describe_for_immutable_place(self.infcx.tcx); |
| opt_source = Some(source); |
| if let Some(desc) = access_place_desc { |
| item_msg = format!("`{}`", desc); |
| reason = match error_access { |
| AccessKind::Mutate => format!(", which is behind {}", pointer_type), |
| AccessKind::MutableBorrow => { |
| format!(", as it is behind {}", pointer_type) |
| } |
| } |
| } else { |
| item_msg = format!("data in {}", pointer_type); |
| reason = String::new(); |
| } |
| } |
| } |
| |
| PlaceRef { |
| local: _, |
| projection: |
| [.., ProjectionElem::Index(_) |
| | ProjectionElem::ConstantIndex { .. } |
| | ProjectionElem::Subslice { .. } |
| | ProjectionElem::Downcast(..)], |
| } => bug!("Unexpected immutable place."), |
| } |
| |
| debug!("report_mutability_error: item_msg={:?}, reason={:?}", item_msg, reason); |
| |
| // `act` and `acted_on` are strings that let us abstract over |
| // the verbs used in some diagnostic messages. |
| let act; |
| let acted_on; |
| |
| let span = match error_access { |
| AccessKind::Mutate => { |
| err = self.cannot_assign(span, &(item_msg + &reason)); |
| act = "assign"; |
| acted_on = "written"; |
| span |
| } |
| AccessKind::MutableBorrow => { |
| act = "borrow as mutable"; |
| acted_on = "borrowed as mutable"; |
| |
| let borrow_spans = self.borrow_spans(span, location); |
| let borrow_span = borrow_spans.args_or_use(); |
| err = self.cannot_borrow_path_as_mutable_because(borrow_span, &item_msg, &reason); |
| borrow_spans.var_span_label( |
| &mut err, |
| format!( |
| "mutable borrow occurs due to use of {} in closure", |
| self.describe_any_place(access_place.as_ref()), |
| ), |
| "mutable", |
| ); |
| borrow_span |
| } |
| }; |
| |
| debug!("report_mutability_error: act={:?}, acted_on={:?}", act, acted_on); |
| |
| match the_place_err { |
| // Suggest making an existing shared borrow in a struct definition a mutable borrow. |
| // |
| // This is applicable when we have a deref of a field access to a deref of a local - |
| // something like `*((*_1).0`. The local that we get will be a reference to the |
| // struct we've got a field access of (it must be a reference since there's a deref |
| // after the field access). |
| PlaceRef { |
| local, |
| projection: |
| [proj_base @ .., ProjectionElem::Deref, ProjectionElem::Field(field, _), ProjectionElem::Deref], |
| } => { |
| err.span_label(span, format!("cannot {ACT}", ACT = act)); |
| |
| if let Some((span, message)) = annotate_struct_field( |
| self.infcx.tcx, |
| Place::ty_from(local, proj_base, self.body, self.infcx.tcx).ty, |
| field, |
| ) { |
| err.span_suggestion( |
| span, |
| "consider changing this to be mutable", |
| message, |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| |
| // Suggest removing a `&mut` from the use of a mutable reference. |
| PlaceRef { local, projection: [] } |
| if self |
| .body |
| .local_decls |
| .get(local) |
| .map(|l| mut_borrow_of_mutable_ref(l, self.local_names[local])) |
| .unwrap_or(false) => |
| { |
| let decl = &self.body.local_decls[local]; |
| err.span_label(span, format!("cannot {ACT}", ACT = act)); |
| if let Some(mir::Statement { |
| source_info, |
| kind: |
| mir::StatementKind::Assign(box ( |
| _, |
| mir::Rvalue::Ref( |
| _, |
| mir::BorrowKind::Mut { allow_two_phase_borrow: false }, |
| _, |
| ), |
| )), |
| .. |
| }) = &self.body[location.block].statements.get(location.statement_index) |
| { |
| match decl.local_info { |
| Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var( |
| mir::VarBindingForm { |
| binding_mode: ty::BindingMode::BindByValue(Mutability::Not), |
| opt_ty_info: Some(sp), |
| opt_match_place: _, |
| pat_span: _, |
| }, |
| )))) => { |
| err.span_note(sp, "the binding is already a mutable borrow"); |
| } |
| _ => { |
| err.span_note( |
| decl.source_info.span, |
| "the binding is already a mutable borrow", |
| ); |
| } |
| } |
| if let Ok(snippet) = |
| self.infcx.tcx.sess.source_map().span_to_snippet(source_info.span) |
| { |
| if snippet.starts_with("&mut ") { |
| // We don't have access to the HIR to get accurate spans, but we can |
| // give a best effort structured suggestion. |
| err.span_suggestion_verbose( |
| source_info.span.with_hi(source_info.span.lo() + BytePos(5)), |
| "try removing `&mut` here", |
| String::new(), |
| Applicability::MachineApplicable, |
| ); |
| } else { |
| // This can occur with things like `(&mut self).foo()`. |
| err.span_help(source_info.span, "try removing `&mut` here"); |
| } |
| } else { |
| err.span_help(source_info.span, "try removing `&mut` here"); |
| } |
| } else if decl.mutability == Mutability::Not |
| && !matches!( |
| decl.local_info, |
| Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf( |
| ImplicitSelfKind::MutRef |
| )))) |
| ) |
| { |
| err.span_suggestion_verbose( |
| decl.source_info.span.shrink_to_lo(), |
| "consider making the binding mutable", |
| "mut ".to_string(), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| // We want to suggest users use `let mut` for local (user |
| // variable) mutations... |
| PlaceRef { local, projection: [] } |
| if self.body.local_decls[local].can_be_made_mutable() => |
| { |
| // ... but it doesn't make sense to suggest it on |
| // variables that are `ref x`, `ref mut x`, `&self`, |
| // or `&mut self` (such variables are simply not |
| // mutable). |
| let local_decl = &self.body.local_decls[local]; |
| assert_eq!(local_decl.mutability, Mutability::Not); |
| |
| err.span_label(span, format!("cannot {ACT}", ACT = act)); |
| err.span_suggestion( |
| local_decl.source_info.span, |
| "consider changing this to be mutable", |
| format!("mut {}", self.local_names[local].unwrap()), |
| Applicability::MachineApplicable, |
| ); |
| let tcx = self.infcx.tcx; |
| if let ty::Closure(id, _) = the_place_err.ty(self.body, tcx).ty.kind() { |
| self.show_mutating_upvar(tcx, id, the_place_err, &mut err); |
| } |
| } |
| |
| // Also suggest adding mut for upvars |
| PlaceRef { |
| local, |
| projection: [proj_base @ .., ProjectionElem::Field(upvar_index, _)], |
| } => { |
| debug_assert!(is_closure_or_generator( |
| Place::ty_from(local, proj_base, self.body, self.infcx.tcx).ty |
| )); |
| |
| let captured_place = &self.upvars[upvar_index.index()].place; |
| |
| err.span_label(span, format!("cannot {ACT}", ACT = act)); |
| |
| let upvar_hir_id = captured_place.get_root_variable(); |
| |
| if let Some(Node::Binding(pat)) = self.infcx.tcx.hir().find(upvar_hir_id) { |
| if let hir::PatKind::Binding( |
| hir::BindingAnnotation::Unannotated, |
| _, |
| upvar_ident, |
| _, |
| ) = pat.kind |
| { |
| err.span_suggestion( |
| upvar_ident.span, |
| "consider changing this to be mutable", |
| format!("mut {}", upvar_ident.name), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| let tcx = self.infcx.tcx; |
| if let ty::Ref(_, ty, Mutability::Mut) = the_place_err.ty(self.body, tcx).ty.kind() |
| { |
| if let ty::Closure(id, _) = ty.kind() { |
| self.show_mutating_upvar(tcx, id, the_place_err, &mut err); |
| } |
| } |
| } |
| |
| // complete hack to approximate old AST-borrowck |
| // diagnostic: if the span starts with a mutable borrow of |
| // a local variable, then just suggest the user remove it. |
| PlaceRef { local: _, projection: [] } |
| if { |
| if let Ok(snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(span) { |
| snippet.starts_with("&mut ") |
| } else { |
| false |
| } |
| } => |
| { |
| err.span_label(span, format!("cannot {ACT}", ACT = act)); |
| err.span_suggestion( |
| span, |
| "try removing `&mut` here", |
| String::new(), |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| |
| PlaceRef { local, projection: [ProjectionElem::Deref] } |
| if self.body.local_decls[local].is_ref_for_guard() => |
| { |
| err.span_label(span, format!("cannot {ACT}", ACT = act)); |
| err.note( |
| "variables bound in patterns are immutable until the end of the pattern guard", |
| ); |
| } |
| |
| // We want to point out when a `&` can be readily replaced |
| // with an `&mut`. |
| // |
| // FIXME: can this case be generalized to work for an |
| // arbitrary base for the projection? |
| PlaceRef { local, projection: [ProjectionElem::Deref] } |
| if self.body.local_decls[local].is_user_variable() => |
| { |
| let local_decl = &self.body.local_decls[local]; |
| |
| let (pointer_sigil, pointer_desc) = if local_decl.ty.is_region_ptr() { |
| ("&", "reference") |
| } else { |
| ("*const", "pointer") |
| }; |
| |
| match self.local_names[local] { |
| Some(name) if !local_decl.from_compiler_desugaring() => { |
| let label = match local_decl.local_info.as_ref().unwrap() { |
| box LocalInfo::User(ClearCrossCrate::Set( |
| mir::BindingForm::ImplicitSelf(_), |
| )) => { |
| let (span, suggestion) = |
| suggest_ampmut_self(self.infcx.tcx, local_decl); |
| Some((true, span, suggestion)) |
| } |
| |
| box LocalInfo::User(ClearCrossCrate::Set(mir::BindingForm::Var( |
| mir::VarBindingForm { |
| binding_mode: ty::BindingMode::BindByValue(_), |
| opt_ty_info, |
| .. |
| }, |
| ))) => { |
| // check if the RHS is from desugaring |
| let locations = self.body.find_assignments(local); |
| let opt_assignment_rhs_span = locations |
| .first() |
| .map(|&location| self.body.source_info(location).span); |
| let opt_desugaring_kind = |
| opt_assignment_rhs_span.and_then(|span| span.desugaring_kind()); |
| match opt_desugaring_kind { |
| // on for loops, RHS points to the iterator part |
| Some(DesugaringKind::ForLoop(_)) => { |
| self.suggest_similar_mut_method_for_for_loop(&mut err); |
| Some(( |
| false, |
| opt_assignment_rhs_span.unwrap(), |
| format!( |
| "this iterator yields `{SIGIL}` {DESC}s", |
| SIGIL = pointer_sigil, |
| DESC = pointer_desc |
| ), |
| )) |
| } |
| // don't create labels for compiler-generated spans |
| Some(_) => None, |
| None => { |
| let (span, suggestion) = suggest_ampmut( |
| self.infcx.tcx, |
| local_decl, |
| opt_assignment_rhs_span, |
| *opt_ty_info, |
| ); |
| Some((true, span, suggestion)) |
| } |
| } |
| } |
| |
| box LocalInfo::User(ClearCrossCrate::Set(mir::BindingForm::Var( |
| mir::VarBindingForm { |
| binding_mode: ty::BindingMode::BindByReference(_), |
| .. |
| }, |
| ))) => { |
| let pattern_span = local_decl.source_info.span; |
| suggest_ref_mut(self.infcx.tcx, pattern_span) |
| .map(|replacement| (true, pattern_span, replacement)) |
| } |
| |
| box LocalInfo::User(ClearCrossCrate::Clear) => { |
| bug!("saw cleared local state") |
| } |
| |
| _ => unreachable!(), |
| }; |
| |
| match label { |
| Some((true, err_help_span, suggested_code)) => { |
| let (is_trait_sig, local_trait) = self.is_error_in_trait(local); |
| if !is_trait_sig { |
| err.span_suggestion( |
| err_help_span, |
| &format!( |
| "consider changing this to be a mutable {}", |
| pointer_desc |
| ), |
| suggested_code, |
| Applicability::MachineApplicable, |
| ); |
| } else if let Some(x) = local_trait { |
| err.span_suggestion( |
| x, |
| &format!( |
| "consider changing that to be a mutable {}", |
| pointer_desc |
| ), |
| suggested_code, |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| Some((false, err_label_span, message)) => { |
| err.span_label(err_label_span, &message); |
| } |
| None => {} |
| } |
| err.span_label( |
| span, |
| format!( |
| "`{NAME}` is a `{SIGIL}` {DESC}, \ |
| so the data it refers to cannot be {ACTED_ON}", |
| NAME = name, |
| SIGIL = pointer_sigil, |
| DESC = pointer_desc, |
| ACTED_ON = acted_on |
| ), |
| ); |
| } |
| _ => { |
| err.span_label( |
| span, |
| format!( |
| "cannot {ACT} through `{SIGIL}` {DESC}", |
| ACT = act, |
| SIGIL = pointer_sigil, |
| DESC = pointer_desc |
| ), |
| ); |
| } |
| } |
| } |
| |
| PlaceRef { local, projection: [ProjectionElem::Deref] } |
| if local == ty::CAPTURE_STRUCT_LOCAL && !self.upvars.is_empty() => |
| { |
| self.expected_fn_found_fn_mut_call(&mut err, span, act); |
| } |
| |
| PlaceRef { local: _, projection: [.., ProjectionElem::Deref] } => { |
| err.span_label(span, format!("cannot {ACT}", ACT = act)); |
| |
| match opt_source { |
| Some(BorrowedContentSource::OverloadedDeref(ty)) => { |
| err.help(&format!( |
| "trait `DerefMut` is required to modify through a dereference, \ |
| but it is not implemented for `{}`", |
| ty, |
| )); |
| } |
| Some(BorrowedContentSource::OverloadedIndex(ty)) => { |
| err.help(&format!( |
| "trait `IndexMut` is required to modify indexed content, \ |
| but it is not implemented for `{}`", |
| ty, |
| )); |
| } |
| _ => (), |
| } |
| } |
| |
| _ => { |
| err.span_label(span, format!("cannot {ACT}", ACT = act)); |
| } |
| } |
| |
| err.buffer(&mut self.errors_buffer); |
| } |
| |
| /// User cannot make signature of a trait mutable without changing the |
| /// trait. So we find if this error belongs to a trait and if so we move |
| /// suggestion to the trait or disable it if it is out of scope of this crate |
| fn is_error_in_trait(&self, local: Local) -> (bool, Option<Span>) { |
| if self.body.local_kind(local) != LocalKind::Arg { |
| return (false, None); |
| } |
| let hir_map = self.infcx.tcx.hir(); |
| let my_def = self.body.source.def_id(); |
| let my_hir = hir_map.local_def_id_to_hir_id(my_def.as_local().unwrap()); |
| let td = if let Some(a) = |
| self.infcx.tcx.impl_of_method(my_def).and_then(|x| self.infcx.tcx.trait_id_of_impl(x)) |
| { |
| a |
| } else { |
| return (false, None); |
| }; |
| ( |
| true, |
| td.as_local().and_then(|tld| { |
| let h = hir_map.local_def_id_to_hir_id(tld); |
| match hir_map.find(h) { |
| Some(Node::Item(hir::Item { |
| kind: hir::ItemKind::Trait(_, _, _, _, items), |
| .. |
| })) => { |
| let mut f_in_trait_opt = None; |
| for hir::TraitItemRef { id: fi, kind: k, .. } in *items { |
| let hi = fi.hir_id(); |
| if !matches!(k, hir::AssocItemKind::Fn { .. }) { |
| continue; |
| } |
| if hir_map.name(hi) != hir_map.name(my_hir) { |
| continue; |
| } |
| f_in_trait_opt = Some(hi); |
| break; |
| } |
| f_in_trait_opt.and_then(|f_in_trait| match hir_map.find(f_in_trait) { |
| Some(Node::TraitItem(hir::TraitItem { |
| kind: |
| hir::TraitItemKind::Fn( |
| hir::FnSig { decl: hir::FnDecl { inputs, .. }, .. }, |
| _, |
| ), |
| .. |
| })) => { |
| let hir::Ty { span, .. } = inputs[local.index() - 1]; |
| Some(span) |
| } |
| _ => None, |
| }) |
| } |
| _ => None, |
| } |
| }), |
| ) |
| } |
| |
| // point to span of upvar making closure call require mutable borrow |
| fn show_mutating_upvar( |
| &self, |
| tcx: TyCtxt<'_>, |
| id: &hir::def_id::DefId, |
| the_place_err: PlaceRef<'tcx>, |
| err: &mut DiagnosticBuilder<'_>, |
| ) { |
| let closure_local_def_id = id.expect_local(); |
| let tables = tcx.typeck(closure_local_def_id); |
| let closure_hir_id = tcx.hir().local_def_id_to_hir_id(closure_local_def_id); |
| if let Some((span, closure_kind_origin)) = |
| &tables.closure_kind_origins().get(closure_hir_id) |
| { |
| let reason = if let PlaceBase::Upvar(upvar_id) = closure_kind_origin.base { |
| let upvar = ty::place_to_string_for_capture(tcx, closure_kind_origin); |
| let root_hir_id = upvar_id.var_path.hir_id; |
| // we have an origin for this closure kind starting at this root variable so it's safe to unwrap here |
| let captured_places = tables.closure_min_captures[id].get(&root_hir_id).unwrap(); |
| |
| let origin_projection = closure_kind_origin |
| .projections |
| .iter() |
| .map(|proj| proj.kind) |
| .collect::<Vec<_>>(); |
| let mut capture_reason = String::new(); |
| for captured_place in captured_places { |
| let captured_place_kinds = captured_place |
| .place |
| .projections |
| .iter() |
| .map(|proj| proj.kind) |
| .collect::<Vec<_>>(); |
| if rustc_middle::ty::is_ancestor_or_same_capture( |
| &captured_place_kinds, |
| &origin_projection, |
| ) { |
| match captured_place.info.capture_kind { |
| ty::UpvarCapture::ByRef(ty::UpvarBorrow { |
| kind: ty::BorrowKind::MutBorrow | ty::BorrowKind::UniqueImmBorrow, |
| .. |
| }) => { |
| capture_reason = format!("mutable borrow of `{}`", upvar); |
| } |
| ty::UpvarCapture::ByValue(_) => { |
| capture_reason = format!("possible mutation of `{}`", upvar); |
| } |
| _ => bug!("upvar `{}` borrowed, but not mutably", upvar), |
| } |
| break; |
| } |
| } |
| if capture_reason.is_empty() { |
| bug!("upvar `{}` borrowed, but cannot find reason", upvar); |
| } |
| capture_reason |
| } else { |
| bug!("not an upvar") |
| }; |
| err.span_label( |
| *span, |
| format!( |
| "calling `{}` requires mutable binding due to {}", |
| self.describe_place(the_place_err).unwrap(), |
| reason |
| ), |
| ); |
| } |
| } |
| |
| // Attempt to search similar mutable associated items for suggestion. |
| // In the future, attempt in all path but initially for RHS of for_loop |
| fn suggest_similar_mut_method_for_for_loop(&self, err: &mut DiagnosticBuilder<'_>) { |
| use hir::{ |
| BodyId, Expr, |
| ExprKind::{Block, Call, DropTemps, Match, MethodCall}, |
| HirId, ImplItem, ImplItemKind, Item, ItemKind, |
| }; |
| |
| fn maybe_body_id_of_fn(hir_map: &Map<'tcx>, id: HirId) -> Option<BodyId> { |
| match hir_map.find(id) { |
| Some(Node::Item(Item { kind: ItemKind::Fn(_, _, body_id), .. })) |
| | Some(Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(_, body_id), .. })) => { |
| Some(*body_id) |
| } |
| _ => None, |
| } |
| } |
| let hir_map = self.infcx.tcx.hir(); |
| let mir_body_hir_id = self.mir_hir_id(); |
| if let Some(fn_body_id) = maybe_body_id_of_fn(&hir_map, mir_body_hir_id) { |
| if let Block( |
| hir::Block { |
| expr: |
| Some(Expr { |
| kind: |
| DropTemps(Expr { |
| kind: |
| Match( |
| Expr { |
| kind: |
| Call( |
| _, |
| [Expr { |
| kind: MethodCall(path_segment, ..), |
| hir_id, |
| .. |
| }, ..], |
| ), |
| .. |
| }, |
| .., |
| ), |
| .. |
| }), |
| .. |
| }), |
| .. |
| }, |
| _, |
| ) = hir_map.body(fn_body_id).value.kind |
| { |
| let opt_suggestions = path_segment |
| .hir_id |
| .map(|path_hir_id| self.infcx.tcx.typeck(path_hir_id.owner)) |
| .and_then(|typeck| typeck.type_dependent_def_id(*hir_id)) |
| .and_then(|def_id| self.infcx.tcx.impl_of_method(def_id)) |
| .map(|def_id| self.infcx.tcx.associated_items(def_id)) |
| .map(|assoc_items| { |
| assoc_items |
| .in_definition_order() |
| .map(|assoc_item_def| assoc_item_def.ident) |
| .filter(|&ident| { |
| let original_method_ident = path_segment.ident; |
| original_method_ident != ident |
| && ident |
| .as_str() |
| .starts_with(&original_method_ident.name.to_string()) |
| }) |
| .map(|ident| format!("{}()", ident)) |
| .peekable() |
| }); |
| |
| if let Some(mut suggestions) = opt_suggestions { |
| if suggestions.peek().is_some() { |
| err.span_suggestions( |
| path_segment.ident.span, |
| "use mutable method", |
| suggestions, |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| } |
| }; |
| } |
| |
| /// Targeted error when encountering an `FnMut` closure where an `Fn` closure was expected. |
| fn expected_fn_found_fn_mut_call(&self, err: &mut DiagnosticBuilder<'_>, sp: Span, act: &str) { |
| err.span_label(sp, format!("cannot {}", act)); |
| |
| let hir = self.infcx.tcx.hir(); |
| let closure_id = self.mir_hir_id(); |
| let fn_call_id = hir.get_parent_node(closure_id); |
| let node = hir.get(fn_call_id); |
| let item_id = hir.enclosing_body_owner(fn_call_id); |
| let mut look_at_return = true; |
| // If we can detect the expression to be an `fn` call where the closure was an argument, |
| // we point at the `fn` definition argument... |
| if let hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Call(func, args), .. }) = node { |
| let arg_pos = args |
| .iter() |
| .enumerate() |
| .filter(|(_, arg)| arg.span == self.body.span) |
| .map(|(pos, _)| pos) |
| .next(); |
| let def_id = hir.local_def_id(item_id); |
| let tables = self.infcx.tcx.typeck(def_id); |
| if let Some(ty::FnDef(def_id, _)) = |
| tables.node_type_opt(func.hir_id).as_ref().map(|ty| ty.kind()) |
| { |
| let arg = match hir.get_if_local(*def_id) { |
| Some( |
| hir::Node::Item(hir::Item { |
| ident, kind: hir::ItemKind::Fn(sig, ..), .. |
| }) |
| | hir::Node::TraitItem(hir::TraitItem { |
| ident, |
| kind: hir::TraitItemKind::Fn(sig, _), |
| .. |
| }) |
| | hir::Node::ImplItem(hir::ImplItem { |
| ident, |
| kind: hir::ImplItemKind::Fn(sig, _), |
| .. |
| }), |
| ) => Some( |
| arg_pos |
| .and_then(|pos| { |
| sig.decl.inputs.get( |
| pos + if sig.decl.implicit_self.has_implicit_self() { |
| 1 |
| } else { |
| 0 |
| }, |
| ) |
| }) |
| .map(|arg| arg.span) |
| .unwrap_or(ident.span), |
| ), |
| _ => None, |
| }; |
| if let Some(span) = arg { |
| err.span_label(span, "change this to accept `FnMut` instead of `Fn`"); |
| err.span_label(func.span, "expects `Fn` instead of `FnMut`"); |
| if self.infcx.tcx.sess.source_map().is_multiline(self.body.span) { |
| err.span_label(self.body.span, "in this closure"); |
| } |
| look_at_return = false; |
| } |
| } |
| } |
| |
| if look_at_return && hir.get_return_block(closure_id).is_some() { |
| // ...otherwise we are probably in the tail expression of the function, point at the |
| // return type. |
| match hir.get(hir.get_parent_item(fn_call_id)) { |
| hir::Node::Item(hir::Item { ident, kind: hir::ItemKind::Fn(sig, ..), .. }) |
| | hir::Node::TraitItem(hir::TraitItem { |
| ident, |
| kind: hir::TraitItemKind::Fn(sig, _), |
| .. |
| }) |
| | hir::Node::ImplItem(hir::ImplItem { |
| ident, |
| kind: hir::ImplItemKind::Fn(sig, _), |
| .. |
| }) => { |
| err.span_label(ident.span, ""); |
| err.span_label( |
| sig.decl.output.span(), |
| "change this to return `FnMut` instead of `Fn`", |
| ); |
| err.span_label(self.body.span, "in this closure"); |
| } |
| _ => {} |
| } |
| } |
| } |
| } |
| |
| fn mut_borrow_of_mutable_ref(local_decl: &LocalDecl<'_>, local_name: Option<Symbol>) -> bool { |
| debug!("local_info: {:?}, ty.kind(): {:?}", local_decl.local_info, local_decl.ty.kind()); |
| |
| match local_decl.local_info.as_deref() { |
| // Check if mutably borrowing a mutable reference. |
| Some(LocalInfo::User(ClearCrossCrate::Set(mir::BindingForm::Var( |
| mir::VarBindingForm { |
| binding_mode: ty::BindingMode::BindByValue(Mutability::Not), .. |
| }, |
| )))) => matches!(local_decl.ty.kind(), ty::Ref(_, _, hir::Mutability::Mut)), |
| Some(LocalInfo::User(ClearCrossCrate::Set(mir::BindingForm::ImplicitSelf(kind)))) => { |
| // Check if the user variable is a `&mut self` and we can therefore |
| // suggest removing the `&mut`. |
| // |
| // Deliberately fall into this case for all implicit self types, |
| // so that we don't fall in to the next case with them. |
| *kind == mir::ImplicitSelfKind::MutRef |
| } |
| _ if Some(kw::SelfLower) == local_name => { |
| // Otherwise, check if the name is the `self` keyword - in which case |
| // we have an explicit self. Do the same thing in this case and check |
| // for a `self: &mut Self` to suggest removing the `&mut`. |
| matches!(local_decl.ty.kind(), ty::Ref(_, _, hir::Mutability::Mut)) |
| } |
| _ => false, |
| } |
| } |
| |
| fn suggest_ampmut_self<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| local_decl: &mir::LocalDecl<'tcx>, |
| ) -> (Span, String) { |
| let sp = local_decl.source_info.span; |
| ( |
| sp, |
| match tcx.sess.source_map().span_to_snippet(sp) { |
| Ok(snippet) => { |
| let lt_pos = snippet.find('\''); |
| if let Some(lt_pos) = lt_pos { |
| format!("&{}mut self", &snippet[lt_pos..snippet.len() - 4]) |
| } else { |
| "&mut self".to_string() |
| } |
| } |
| _ => "&mut self".to_string(), |
| }, |
| ) |
| } |
| |
| // When we want to suggest a user change a local variable to be a `&mut`, there |
| // are three potential "obvious" things to highlight: |
| // |
| // let ident [: Type] [= RightHandSideExpression]; |
| // ^^^^^ ^^^^ ^^^^^^^^^^^^^^^^^^^^^^^ |
| // (1.) (2.) (3.) |
| // |
| // We can always fallback on highlighting the first. But chances are good that |
| // the user experience will be better if we highlight one of the others if possible; |
| // for example, if the RHS is present and the Type is not, then the type is going to |
| // be inferred *from* the RHS, which means we should highlight that (and suggest |
| // that they borrow the RHS mutably). |
| // |
| // This implementation attempts to emulate AST-borrowck prioritization |
| // by trying (3.), then (2.) and finally falling back on (1.). |
| fn suggest_ampmut<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| local_decl: &mir::LocalDecl<'tcx>, |
| opt_assignment_rhs_span: Option<Span>, |
| opt_ty_info: Option<Span>, |
| ) -> (Span, String) { |
| if let Some(assignment_rhs_span) = opt_assignment_rhs_span { |
| if let Ok(src) = tcx.sess.source_map().span_to_snippet(assignment_rhs_span) { |
| let is_mutbl = |ty: &str| -> bool { |
| if let Some(rest) = ty.strip_prefix("mut") { |
| match rest.chars().next() { |
| // e.g. `&mut x` |
| Some(c) if c.is_whitespace() => true, |
| // e.g. `&mut(x)` |
| Some('(') => true, |
| // e.g. `&mut{x}` |
| Some('{') => true, |
| // e.g. `&mutablevar` |
| _ => false, |
| } |
| } else { |
| false |
| } |
| }; |
| if let (true, Some(ws_pos)) = (src.starts_with("&'"), src.find(char::is_whitespace)) { |
| let lt_name = &src[1..ws_pos]; |
| let ty = src[ws_pos..].trim_start(); |
| if !is_mutbl(ty) { |
| return (assignment_rhs_span, format!("&{} mut {}", lt_name, ty)); |
| } |
| } else if let Some(stripped) = src.strip_prefix('&') { |
| let stripped = stripped.trim_start(); |
| if !is_mutbl(stripped) { |
| return (assignment_rhs_span, format!("&mut {}", stripped)); |
| } |
| } |
| } |
| } |
| |
| let highlight_span = match opt_ty_info { |
| // if this is a variable binding with an explicit type, |
| // try to highlight that for the suggestion. |
| Some(ty_span) => ty_span, |
| |
| // otherwise, just highlight the span associated with |
| // the (MIR) LocalDecl. |
| None => local_decl.source_info.span, |
| }; |
| |
| if let Ok(src) = tcx.sess.source_map().span_to_snippet(highlight_span) { |
| if let (true, Some(ws_pos)) = (src.starts_with("&'"), src.find(char::is_whitespace)) { |
| let lt_name = &src[1..ws_pos]; |
| let ty = &src[ws_pos..]; |
| return (highlight_span, format!("&{} mut{}", lt_name, ty)); |
| } |
| } |
| |
| let ty_mut = local_decl.ty.builtin_deref(true).unwrap(); |
| assert_eq!(ty_mut.mutbl, hir::Mutability::Not); |
| ( |
| highlight_span, |
| if local_decl.ty.is_region_ptr() { |
| format!("&mut {}", ty_mut.ty) |
| } else { |
| format!("*mut {}", ty_mut.ty) |
| }, |
| ) |
| } |
| |
| fn is_closure_or_generator(ty: Ty<'_>) -> bool { |
| ty.is_closure() || ty.is_generator() |
| } |
| |
| /// Adds a suggestion to a struct definition given a field access to a local. |
| /// This function expects the local to be a reference to a struct in order to produce a suggestion. |
| /// |
| /// ```text |
| /// LL | s: &'a String |
| /// | ---------- use `&'a mut String` here to make mutable |
| /// ``` |
| fn annotate_struct_field( |
| tcx: TyCtxt<'tcx>, |
| ty: Ty<'tcx>, |
| field: &mir::Field, |
| ) -> Option<(Span, String)> { |
| // Expect our local to be a reference to a struct of some kind. |
| if let ty::Ref(_, ty, _) = ty.kind() { |
| if let ty::Adt(def, _) = ty.kind() { |
| let field = def.all_fields().nth(field.index())?; |
| // Use the HIR types to construct the diagnostic message. |
| let hir_id = tcx.hir().local_def_id_to_hir_id(field.did.as_local()?); |
| let node = tcx.hir().find(hir_id)?; |
| // Now we're dealing with the actual struct that we're going to suggest a change to, |
| // we can expect a field that is an immutable reference to a type. |
| if let hir::Node::Field(field) = node { |
| if let hir::TyKind::Rptr( |
| lifetime, |
| hir::MutTy { mutbl: hir::Mutability::Not, ref ty }, |
| ) = field.ty.kind |
| { |
| // Get the snippets in two parts - the named lifetime (if there is one) and |
| // type being referenced, that way we can reconstruct the snippet without loss |
| // of detail. |
| let type_snippet = tcx.sess.source_map().span_to_snippet(ty.span).ok()?; |
| let lifetime_snippet = if !lifetime.is_elided() { |
| format!("{} ", tcx.sess.source_map().span_to_snippet(lifetime.span).ok()?) |
| } else { |
| String::new() |
| }; |
| |
| return Some(( |
| field.ty.span, |
| format!("&{}mut {}", lifetime_snippet, &*type_snippet,), |
| )); |
| } |
| } |
| } |
| } |
| |
| None |
| } |
| |
| /// If possible, suggest replacing `ref` with `ref mut`. |
| fn suggest_ref_mut(tcx: TyCtxt<'_>, binding_span: Span) -> Option<String> { |
| let hi_src = tcx.sess.source_map().span_to_snippet(binding_span).ok()?; |
| if hi_src.starts_with("ref") && hi_src["ref".len()..].starts_with(rustc_lexer::is_whitespace) { |
| let replacement = format!("ref mut{}", &hi_src["ref".len()..]); |
| Some(replacement) |
| } else { |
| None |
| } |
| } |
