| // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //! See The Book chapter on the borrow checker for more details. |
| |
| #![allow(non_camel_case_types)] |
| |
| pub use self::LoanPathKind::*; |
| pub use self::LoanPathElem::*; |
| pub use self::bckerr_code::*; |
| pub use self::AliasableViolationKind::*; |
| pub use self::MovedValueUseKind::*; |
| |
| use self::InteriorKind::*; |
| |
| use rustc::hir::HirId; |
| use rustc::hir::map as hir_map; |
| use rustc::hir::map::blocks::FnLikeNode; |
| use rustc::cfg; |
| use rustc::middle::dataflow::DataFlowContext; |
| use rustc::middle::dataflow::BitwiseOperator; |
| use rustc::middle::dataflow::DataFlowOperator; |
| use rustc::middle::dataflow::KillFrom; |
| use rustc::middle::borrowck::BorrowCheckResult; |
| use rustc::hir::def_id::{DefId, LocalDefId}; |
| use rustc::middle::expr_use_visitor as euv; |
| use rustc::middle::mem_categorization as mc; |
| use rustc::middle::mem_categorization::Categorization; |
| use rustc::middle::mem_categorization::ImmutabilityBlame; |
| use rustc::middle::region; |
| use rustc::middle::free_region::RegionRelations; |
| use rustc::ty::{self, Ty, TyCtxt}; |
| use rustc::ty::maps::Providers; |
| use rustc_mir::util::borrowck_errors::{BorrowckErrors, Origin}; |
| use rustc::util::nodemap::FxHashSet; |
| |
| use std::cell::RefCell; |
| use std::fmt; |
| use std::rc::Rc; |
| use std::hash::{Hash, Hasher}; |
| use syntax::ast; |
| use syntax_pos::{MultiSpan, Span}; |
| use errors::{DiagnosticBuilder, DiagnosticId}; |
| |
| use rustc::hir; |
| use rustc::hir::intravisit::{self, Visitor}; |
| |
| pub mod check_loans; |
| |
| pub mod gather_loans; |
| |
| pub mod move_data; |
| |
| mod unused; |
| |
| #[derive(Clone, Copy)] |
| pub struct LoanDataFlowOperator; |
| |
| pub type LoanDataFlow<'a, 'tcx> = DataFlowContext<'a, 'tcx, LoanDataFlowOperator>; |
| |
| pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) { |
| for body_owner_def_id in tcx.body_owners() { |
| tcx.borrowck(body_owner_def_id); |
| } |
| } |
| |
| pub fn provide(providers: &mut Providers) { |
| *providers = Providers { |
| borrowck, |
| ..*providers |
| }; |
| } |
| |
| /// Collection of conclusions determined via borrow checker analyses. |
| pub struct AnalysisData<'a, 'tcx: 'a> { |
| pub all_loans: Vec<Loan<'tcx>>, |
| pub loans: DataFlowContext<'a, 'tcx, LoanDataFlowOperator>, |
| pub move_data: move_data::FlowedMoveData<'a, 'tcx>, |
| } |
| |
| fn borrowck<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, owner_def_id: DefId) |
| -> Rc<BorrowCheckResult> |
| { |
| debug!("borrowck(body_owner_def_id={:?})", owner_def_id); |
| |
| let owner_id = tcx.hir.as_local_node_id(owner_def_id).unwrap(); |
| |
| match tcx.hir.get(owner_id) { |
| hir_map::NodeStructCtor(_) | |
| hir_map::NodeVariant(_) => { |
| // We get invoked with anything that has MIR, but some of |
| // those things (notably the synthesized constructors from |
| // tuple structs/variants) do not have an associated body |
| // and do not need borrowchecking. |
| return Rc::new(BorrowCheckResult { |
| used_mut_nodes: FxHashSet(), |
| }) |
| } |
| _ => { } |
| } |
| |
| let body_id = tcx.hir.body_owned_by(owner_id); |
| let tables = tcx.typeck_tables_of(owner_def_id); |
| let region_scope_tree = tcx.region_scope_tree(owner_def_id); |
| let body = tcx.hir.body(body_id); |
| let mut bccx = BorrowckCtxt { |
| tcx, |
| tables, |
| region_scope_tree, |
| owner_def_id, |
| body, |
| used_mut_nodes: RefCell::new(FxHashSet()), |
| }; |
| |
| // Eventually, borrowck will always read the MIR, but at the |
| // moment we do not. So, for now, we always force MIR to be |
| // constructed for a given fn, since this may result in errors |
| // being reported and we want that to happen. |
| // |
| // Note that `mir_validated` is a "stealable" result; the |
| // thief, `optimized_mir()`, forces borrowck, so we know that |
| // is not yet stolen. |
| tcx.mir_validated(owner_def_id).borrow(); |
| |
| // option dance because you can't capture an uninitialized variable |
| // by mut-ref. |
| let mut cfg = None; |
| if let Some(AnalysisData { all_loans, |
| loans: loan_dfcx, |
| move_data: flowed_moves }) = |
| build_borrowck_dataflow_data(&mut bccx, false, body_id, |
| |bccx| { |
| cfg = Some(cfg::CFG::new(bccx.tcx, &body)); |
| cfg.as_mut().unwrap() |
| }) |
| { |
| check_loans::check_loans(&mut bccx, &loan_dfcx, &flowed_moves, &all_loans, body); |
| } |
| unused::check(&mut bccx, body); |
| |
| Rc::new(BorrowCheckResult { |
| used_mut_nodes: bccx.used_mut_nodes.into_inner(), |
| }) |
| } |
| |
| fn build_borrowck_dataflow_data<'a, 'c, 'tcx, F>(this: &mut BorrowckCtxt<'a, 'tcx>, |
| force_analysis: bool, |
| body_id: hir::BodyId, |
| get_cfg: F) |
| -> Option<AnalysisData<'a, 'tcx>> |
| where F: FnOnce(&mut BorrowckCtxt<'a, 'tcx>) -> &'c cfg::CFG |
| { |
| // Check the body of fn items. |
| let tcx = this.tcx; |
| let id_range = { |
| let mut visitor = intravisit::IdRangeComputingVisitor::new(&tcx.hir); |
| visitor.visit_body(this.body); |
| visitor.result() |
| }; |
| let (all_loans, move_data) = |
| gather_loans::gather_loans_in_fn(this, body_id); |
| |
| if !force_analysis && move_data.is_empty() && all_loans.is_empty() { |
| // large arrays of data inserted as constants can take a lot of |
| // time and memory to borrow-check - see issue #36799. However, |
| // they don't have lvalues, so no borrow-check is actually needed. |
| // Recognize that case and skip borrow-checking. |
| debug!("skipping loan propagation for {:?} because of no loans", body_id); |
| return None; |
| } else { |
| debug!("propagating loans in {:?}", body_id); |
| } |
| |
| let cfg = get_cfg(this); |
| let mut loan_dfcx = |
| DataFlowContext::new(this.tcx, |
| "borrowck", |
| Some(this.body), |
| cfg, |
| LoanDataFlowOperator, |
| id_range, |
| all_loans.len()); |
| for (loan_idx, loan) in all_loans.iter().enumerate() { |
| loan_dfcx.add_gen(loan.gen_scope.item_local_id(), loan_idx); |
| loan_dfcx.add_kill(KillFrom::ScopeEnd, |
| loan.kill_scope.item_local_id(), |
| loan_idx); |
| } |
| loan_dfcx.add_kills_from_flow_exits(cfg); |
| loan_dfcx.propagate(cfg, this.body); |
| |
| let flowed_moves = move_data::FlowedMoveData::new(move_data, |
| this, |
| cfg, |
| id_range, |
| this.body); |
| |
| Some(AnalysisData { all_loans, |
| loans: loan_dfcx, |
| move_data:flowed_moves }) |
| } |
| |
| /// Accessor for introspective clients inspecting `AnalysisData` and |
| /// the `BorrowckCtxt` itself , e.g. the flowgraph visualizer. |
| pub fn build_borrowck_dataflow_data_for_fn<'a, 'tcx>( |
| tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| body_id: hir::BodyId, |
| cfg: &cfg::CFG) |
| -> (BorrowckCtxt<'a, 'tcx>, AnalysisData<'a, 'tcx>) |
| { |
| let owner_id = tcx.hir.body_owner(body_id); |
| let owner_def_id = tcx.hir.local_def_id(owner_id); |
| let tables = tcx.typeck_tables_of(owner_def_id); |
| let region_scope_tree = tcx.region_scope_tree(owner_def_id); |
| let body = tcx.hir.body(body_id); |
| let mut bccx = BorrowckCtxt { |
| tcx, |
| tables, |
| region_scope_tree, |
| owner_def_id, |
| body, |
| used_mut_nodes: RefCell::new(FxHashSet()), |
| }; |
| |
| let dataflow_data = build_borrowck_dataflow_data(&mut bccx, true, body_id, |_| cfg); |
| (bccx, dataflow_data.unwrap()) |
| } |
| |
| // ---------------------------------------------------------------------- |
| // Type definitions |
| |
| pub struct BorrowckCtxt<'a, 'tcx: 'a> { |
| tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| |
| // tables for the current thing we are checking; set to |
| // Some in `borrowck_fn` and cleared later |
| tables: &'a ty::TypeckTables<'tcx>, |
| |
| region_scope_tree: Rc<region::ScopeTree>, |
| |
| owner_def_id: DefId, |
| |
| body: &'tcx hir::Body, |
| |
| used_mut_nodes: RefCell<FxHashSet<HirId>>, |
| } |
| |
| impl<'b, 'tcx: 'b> BorrowckErrors for BorrowckCtxt<'b, 'tcx> { |
| fn struct_span_err_with_code<'a, S: Into<MultiSpan>>(&'a self, |
| sp: S, |
| msg: &str, |
| code: DiagnosticId) |
| -> DiagnosticBuilder<'a> |
| { |
| self.tcx.sess.struct_span_err_with_code(sp, msg, code) |
| } |
| |
| fn struct_span_err<'a, S: Into<MultiSpan>>(&'a self, |
| sp: S, |
| msg: &str) |
| -> DiagnosticBuilder<'a> |
| { |
| self.tcx.sess.struct_span_err(sp, msg) |
| } |
| |
| fn cancel_if_wrong_origin<'a>(&'a self, |
| mut diag: DiagnosticBuilder<'a>, |
| o: Origin) |
| -> DiagnosticBuilder<'a> |
| { |
| if !o.should_emit_errors(self.tcx.sess.borrowck_mode()) { |
| self.tcx.sess.diagnostic().cancel(&mut diag); |
| } |
| diag |
| } |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Loans and loan paths |
| |
| /// Record of a loan that was issued. |
| pub struct Loan<'tcx> { |
| index: usize, |
| loan_path: Rc<LoanPath<'tcx>>, |
| kind: ty::BorrowKind, |
| restricted_paths: Vec<Rc<LoanPath<'tcx>>>, |
| |
| /// gen_scope indicates where loan is introduced. Typically the |
| /// loan is introduced at the point of the borrow, but in some |
| /// cases, notably method arguments, the loan may be introduced |
| /// only later, once it comes into scope. See also |
| /// `GatherLoanCtxt::compute_gen_scope`. |
| gen_scope: region::Scope, |
| |
| /// kill_scope indicates when the loan goes out of scope. This is |
| /// either when the lifetime expires or when the local variable |
| /// which roots the loan-path goes out of scope, whichever happens |
| /// faster. See also `GatherLoanCtxt::compute_kill_scope`. |
| kill_scope: region::Scope, |
| span: Span, |
| cause: euv::LoanCause, |
| } |
| |
| impl<'tcx> Loan<'tcx> { |
| pub fn loan_path(&self) -> Rc<LoanPath<'tcx>> { |
| self.loan_path.clone() |
| } |
| } |
| |
| #[derive(Eq)] |
| pub struct LoanPath<'tcx> { |
| kind: LoanPathKind<'tcx>, |
| ty: Ty<'tcx>, |
| } |
| |
| impl<'tcx> PartialEq for LoanPath<'tcx> { |
| fn eq(&self, that: &LoanPath<'tcx>) -> bool { |
| self.kind == that.kind |
| } |
| } |
| |
| impl<'tcx> Hash for LoanPath<'tcx> { |
| fn hash<H: Hasher>(&self, state: &mut H) { |
| self.kind.hash(state); |
| } |
| } |
| |
| #[derive(PartialEq, Eq, Hash, Debug)] |
| pub enum LoanPathKind<'tcx> { |
| LpVar(ast::NodeId), // `x` in README.md |
| LpUpvar(ty::UpvarId), // `x` captured by-value into closure |
| LpDowncast(Rc<LoanPath<'tcx>>, DefId), // `x` downcast to particular enum variant |
| LpExtend(Rc<LoanPath<'tcx>>, mc::MutabilityCategory, LoanPathElem<'tcx>) |
| } |
| |
| impl<'tcx> LoanPath<'tcx> { |
| fn new(kind: LoanPathKind<'tcx>, ty: Ty<'tcx>) -> LoanPath<'tcx> { |
| LoanPath { kind: kind, ty: ty } |
| } |
| |
| fn to_type(&self) -> Ty<'tcx> { self.ty } |
| |
| fn has_downcast(&self) -> bool { |
| match self.kind { |
| LpDowncast(_, _) => true, |
| LpExtend(ref lp, _, LpInterior(_, _)) => { |
| lp.has_downcast() |
| } |
| _ => false, |
| } |
| } |
| } |
| |
| // FIXME (pnkfelix): See discussion here |
| // https://github.com/pnkfelix/rust/commit/ |
| // b2b39e8700e37ad32b486b9a8409b50a8a53aa51#commitcomment-7892003 |
| const DOWNCAST_PRINTED_OPERATOR: &'static str = " as "; |
| |
| // A local, "cleaned" version of `mc::InteriorKind` that drops |
| // information that is not relevant to loan-path analysis. (In |
| // particular, the distinction between how precisely an array-element |
| // is tracked is irrelevant here.) |
| #[derive(Clone, Copy, PartialEq, Eq, Hash)] |
| pub enum InteriorKind { |
| InteriorField(mc::FieldName), |
| InteriorElement, |
| } |
| |
| trait ToInteriorKind { fn cleaned(self) -> InteriorKind; } |
| impl ToInteriorKind for mc::InteriorKind { |
| fn cleaned(self) -> InteriorKind { |
| match self { |
| mc::InteriorField(name) => InteriorField(name), |
| mc::InteriorElement(_) => InteriorElement, |
| } |
| } |
| } |
| |
| // This can be: |
| // - a pointer dereference (`*LV` in README.md) |
| // - a field reference, with an optional definition of the containing |
| // enum variant (`LV.f` in README.md) |
| // `DefId` is present when the field is part of struct that is in |
| // a variant of an enum. For instance in: |
| // `enum E { X { foo: u32 }, Y { foo: u32 }}` |
| // each `foo` is qualified by the definitition id of the variant (`X` or `Y`). |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] |
| pub enum LoanPathElem<'tcx> { |
| LpDeref(mc::PointerKind<'tcx>), |
| LpInterior(Option<DefId>, InteriorKind), |
| } |
| |
| fn closure_to_block(closure_id: LocalDefId, |
| tcx: TyCtxt) -> ast::NodeId { |
| let closure_id = tcx.hir.local_def_id_to_node_id(closure_id); |
| match tcx.hir.get(closure_id) { |
| hir_map::NodeExpr(expr) => match expr.node { |
| hir::ExprClosure(.., body_id, _, _) => { |
| body_id.node_id |
| } |
| _ => { |
| bug!("encountered non-closure id: {}", closure_id) |
| } |
| }, |
| _ => bug!("encountered non-expr id: {}", closure_id) |
| } |
| } |
| |
| impl<'a, 'tcx> LoanPath<'tcx> { |
| pub fn kill_scope(&self, bccx: &BorrowckCtxt<'a, 'tcx>) -> region::Scope { |
| match self.kind { |
| LpVar(local_id) => { |
| let hir_id = bccx.tcx.hir.node_to_hir_id(local_id); |
| bccx.region_scope_tree.var_scope(hir_id.local_id) |
| } |
| LpUpvar(upvar_id) => { |
| let block_id = closure_to_block(upvar_id.closure_expr_id, bccx.tcx); |
| let hir_id = bccx.tcx.hir.node_to_hir_id(block_id); |
| region::Scope::Node(hir_id.local_id) |
| } |
| LpDowncast(ref base, _) | |
| LpExtend(ref base, ..) => base.kill_scope(bccx), |
| } |
| } |
| |
| fn has_fork(&self, other: &LoanPath<'tcx>) -> bool { |
| match (&self.kind, &other.kind) { |
| (&LpExtend(ref base, _, LpInterior(opt_variant_id, id)), |
| &LpExtend(ref base2, _, LpInterior(opt_variant_id2, id2))) => |
| if id == id2 && opt_variant_id == opt_variant_id2 { |
| base.has_fork(&base2) |
| } else { |
| true |
| }, |
| (&LpExtend(ref base, _, LpDeref(_)), _) => base.has_fork(other), |
| (_, &LpExtend(ref base, _, LpDeref(_))) => self.has_fork(&base), |
| _ => false, |
| } |
| } |
| |
| fn depth(&self) -> usize { |
| match self.kind { |
| LpExtend(ref base, _, LpDeref(_)) => base.depth(), |
| LpExtend(ref base, _, LpInterior(..)) => base.depth() + 1, |
| _ => 0, |
| } |
| } |
| |
| fn common(&self, other: &LoanPath<'tcx>) -> Option<LoanPath<'tcx>> { |
| match (&self.kind, &other.kind) { |
| (&LpExtend(ref base, a, LpInterior(opt_variant_id, id)), |
| &LpExtend(ref base2, _, LpInterior(opt_variant_id2, id2))) => { |
| if id == id2 && opt_variant_id == opt_variant_id2 { |
| base.common(&base2).map(|x| { |
| let xd = x.depth(); |
| if base.depth() == xd && base2.depth() == xd { |
| LoanPath { |
| kind: LpExtend(Rc::new(x), a, LpInterior(opt_variant_id, id)), |
| ty: self.ty, |
| } |
| } else { |
| x |
| } |
| }) |
| } else { |
| base.common(&base2) |
| } |
| } |
| (&LpExtend(ref base, _, LpDeref(_)), _) => base.common(other), |
| (_, &LpExtend(ref other, _, LpDeref(_))) => self.common(&other), |
| (&LpVar(id), &LpVar(id2)) => { |
| if id == id2 { |
| Some(LoanPath { kind: LpVar(id), ty: self.ty }) |
| } else { |
| None |
| } |
| } |
| (&LpUpvar(id), &LpUpvar(id2)) => { |
| if id == id2 { |
| Some(LoanPath { kind: LpUpvar(id), ty: self.ty }) |
| } else { |
| None |
| } |
| } |
| _ => None, |
| } |
| } |
| } |
| |
| // Avoid "cannot borrow immutable field `self.x` as mutable" as that implies that a field *can* be |
| // mutable independently of the struct it belongs to. (#35937) |
| pub fn opt_loan_path_is_field<'tcx>(cmt: &mc::cmt<'tcx>) -> (Option<Rc<LoanPath<'tcx>>>, bool) { |
| let new_lp = |v: LoanPathKind<'tcx>| Rc::new(LoanPath::new(v, cmt.ty)); |
| |
| match cmt.cat { |
| Categorization::Rvalue(..) | |
| Categorization::StaticItem => { |
| (None, false) |
| } |
| |
| Categorization::Local(id) => { |
| (Some(new_lp(LpVar(id))), false) |
| } |
| |
| Categorization::Upvar(mc::Upvar { id, .. }) => { |
| (Some(new_lp(LpUpvar(id))), false) |
| } |
| |
| Categorization::Deref(ref cmt_base, pk) => { |
| let lp = opt_loan_path_is_field(cmt_base); |
| (lp.0.map(|lp| { |
| new_lp(LpExtend(lp, cmt.mutbl, LpDeref(pk))) |
| }), lp.1) |
| } |
| |
| Categorization::Interior(ref cmt_base, ik) => { |
| (opt_loan_path(cmt_base).map(|lp| { |
| let opt_variant_id = match cmt_base.cat { |
| Categorization::Downcast(_, did) => Some(did), |
| _ => None |
| }; |
| new_lp(LpExtend(lp, cmt.mutbl, LpInterior(opt_variant_id, ik.cleaned()))) |
| }), true) |
| } |
| |
| Categorization::Downcast(ref cmt_base, variant_def_id) => { |
| let lp = opt_loan_path_is_field(cmt_base); |
| (lp.0.map(|lp| { |
| new_lp(LpDowncast(lp, variant_def_id)) |
| }), lp.1) |
| } |
| } |
| } |
| |
| /// Computes the `LoanPath` (if any) for a `cmt`. |
| /// Note that this logic is somewhat duplicated in |
| /// the method `compute()` found in `gather_loans::restrictions`, |
| /// which allows it to share common loan path pieces as it |
| /// traverses the CMT. |
| pub fn opt_loan_path<'tcx>(cmt: &mc::cmt<'tcx>) -> Option<Rc<LoanPath<'tcx>>> { |
| opt_loan_path_is_field(cmt).0 |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Errors |
| |
| // Errors that can occur |
| #[derive(Debug, PartialEq)] |
| pub enum bckerr_code<'tcx> { |
| err_mutbl, |
| /// superscope, subscope, loan cause |
| err_out_of_scope(ty::Region<'tcx>, ty::Region<'tcx>, euv::LoanCause), |
| err_borrowed_pointer_too_short(ty::Region<'tcx>, ty::Region<'tcx>), // loan, ptr |
| } |
| |
| // Combination of an error code and the categorization of the expression |
| // that caused it |
| #[derive(Debug, PartialEq)] |
| pub struct BckError<'tcx> { |
| span: Span, |
| cause: AliasableViolationKind, |
| cmt: mc::cmt<'tcx>, |
| code: bckerr_code<'tcx> |
| } |
| |
| #[derive(Copy, Clone, Debug, PartialEq)] |
| pub enum AliasableViolationKind { |
| MutabilityViolation, |
| BorrowViolation(euv::LoanCause) |
| } |
| |
| #[derive(Copy, Clone, Debug)] |
| pub enum MovedValueUseKind { |
| MovedInUse, |
| MovedInCapture, |
| } |
| |
| /////////////////////////////////////////////////////////////////////////// |
| // Misc |
| |
| impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> { |
| pub fn is_subregion_of(&self, |
| r_sub: ty::Region<'tcx>, |
| r_sup: ty::Region<'tcx>) |
| -> bool |
| { |
| let region_rels = RegionRelations::new(self.tcx, |
| self.owner_def_id, |
| &self.region_scope_tree, |
| &self.tables.free_region_map); |
| region_rels.is_subregion_of(r_sub, r_sup) |
| } |
| |
| pub fn report(&self, err: BckError<'tcx>) { |
| // Catch and handle some particular cases. |
| match (&err.code, &err.cause) { |
| (&err_out_of_scope(&ty::ReScope(_), &ty::ReStatic, _), |
| &BorrowViolation(euv::ClosureCapture(span))) | |
| (&err_out_of_scope(&ty::ReScope(_), &ty::ReEarlyBound(..), _), |
| &BorrowViolation(euv::ClosureCapture(span))) | |
| (&err_out_of_scope(&ty::ReScope(_), &ty::ReFree(..), _), |
| &BorrowViolation(euv::ClosureCapture(span))) => { |
| return self.report_out_of_scope_escaping_closure_capture(&err, span); |
| } |
| _ => { } |
| } |
| |
| self.report_bckerr(&err); |
| } |
| |
| pub fn report_use_of_moved_value(&self, |
| use_span: Span, |
| use_kind: MovedValueUseKind, |
| lp: &LoanPath<'tcx>, |
| the_move: &move_data::Move, |
| moved_lp: &LoanPath<'tcx>, |
| _param_env: ty::ParamEnv<'tcx>) { |
| let (verb, verb_participle) = match use_kind { |
| MovedInUse => ("use", "used"), |
| MovedInCapture => ("capture", "captured"), |
| }; |
| |
| let (_ol, _moved_lp_msg, mut err, need_note) = match the_move.kind { |
| move_data::Declared => { |
| // If this is an uninitialized variable, just emit a simple warning |
| // and return. |
| self.cannot_act_on_uninitialized_variable(use_span, |
| verb, |
| &self.loan_path_to_string(lp), |
| Origin::Ast) |
| .span_label(use_span, format!("use of possibly uninitialized `{}`", |
| self.loan_path_to_string(lp))) |
| .emit(); |
| return; |
| } |
| _ => { |
| // If moved_lp is something like `x.a`, and lp is something like `x.b`, we would |
| // normally generate a rather confusing message: |
| // |
| // error: use of moved value: `x.b` |
| // note: `x.a` moved here... |
| // |
| // What we want to do instead is get the 'common ancestor' of the two moves and |
| // use that for most of the message instead, giving is something like this: |
| // |
| // error: use of moved value: `x` |
| // note: `x` moved here (through moving `x.a`)... |
| |
| let common = moved_lp.common(lp); |
| let has_common = common.is_some(); |
| let has_fork = moved_lp.has_fork(lp); |
| let (nl, ol, moved_lp_msg) = |
| if has_fork && has_common { |
| let nl = self.loan_path_to_string(&common.unwrap()); |
| let ol = nl.clone(); |
| let moved_lp_msg = format!(" (through moving `{}`)", |
| self.loan_path_to_string(moved_lp)); |
| (nl, ol, moved_lp_msg) |
| } else { |
| (self.loan_path_to_string(lp), |
| self.loan_path_to_string(moved_lp), |
| String::new()) |
| }; |
| |
| let partial = moved_lp.depth() > lp.depth(); |
| let msg = if !has_fork && partial { "partially " } |
| else if has_fork && !has_common { "collaterally "} |
| else { "" }; |
| let mut err = self.cannot_act_on_moved_value(use_span, |
| verb, |
| msg, |
| &format!("{}", nl), |
| Origin::Ast); |
| let need_note = match lp.ty.sty { |
| ty::TypeVariants::TyClosure(id, _) => { |
| let node_id = self.tcx.hir.as_local_node_id(id).unwrap(); |
| let hir_id = self.tcx.hir.node_to_hir_id(node_id); |
| if let Some((span, name)) = self.tables.closure_kind_origins().get(hir_id) { |
| err.span_note(*span, &format!( |
| "closure cannot be invoked more than once because \ |
| it moves the variable `{}` out of its environment", |
| name |
| )); |
| false |
| } else { |
| true |
| } |
| } |
| _ => true, |
| }; |
| (ol, moved_lp_msg, err, need_note) |
| } |
| }; |
| |
| // Get type of value and span where it was previously |
| // moved. |
| let node_id = self.tcx.hir.hir_to_node_id(hir::HirId { |
| owner: self.body.value.hir_id.owner, |
| local_id: the_move.id |
| }); |
| let (move_span, move_note) = match the_move.kind { |
| move_data::Declared => { |
| unreachable!(); |
| } |
| |
| move_data::MoveExpr | |
| move_data::MovePat => (self.tcx.hir.span(node_id), ""), |
| |
| move_data::Captured => |
| (match self.tcx.hir.expect_expr(node_id).node { |
| hir::ExprClosure(.., fn_decl_span, _) => fn_decl_span, |
| ref r => bug!("Captured({:?}) maps to non-closure: {:?}", |
| the_move.id, r), |
| }, " (into closure)"), |
| }; |
| |
| // Annotate the use and the move in the span. Watch out for |
| // the case where the use and the move are the same. This |
| // means the use is in a loop. |
| err = if use_span == move_span { |
| err.span_label( |
| use_span, |
| format!("value moved{} here in previous iteration of loop", |
| move_note)); |
| err |
| } else { |
| err.span_label(use_span, format!("value {} here after move", verb_participle)); |
| err.span_label(move_span, format!("value moved{} here", move_note)); |
| err |
| }; |
| |
| if need_note { |
| err.note(&format!( |
| "move occurs because {} has type `{}`, which does not implement the `Copy` trait", |
| if moved_lp.has_downcast() { |
| "the value".to_string() |
| } else { |
| format!("`{}`", self.loan_path_to_string(moved_lp)) |
| }, |
| moved_lp.ty)); |
| } |
| |
| // Note: we used to suggest adding a `ref binding` or calling |
| // `clone` but those suggestions have been removed because |
| // they are often not what you actually want to do, and were |
| // not considered particularly helpful. |
| |
| err.emit(); |
| } |
| |
| pub fn report_partial_reinitialization_of_uninitialized_structure( |
| &self, |
| span: Span, |
| lp: &LoanPath<'tcx>) { |
| self.cannot_partially_reinit_an_uninit_struct(span, |
| &self.loan_path_to_string(lp), |
| Origin::Ast) |
| .emit(); |
| } |
| |
| pub fn report_reassigned_immutable_variable(&self, |
| span: Span, |
| lp: &LoanPath<'tcx>, |
| assign: |
| &move_data::Assignment) { |
| let mut err = self.cannot_reassign_immutable(span, |
| &self.loan_path_to_string(lp), |
| Origin::Ast); |
| err.span_label(span, "cannot assign twice to immutable variable"); |
| if span != assign.span { |
| err.span_label(assign.span, format!("first assignment to `{}`", |
| self.loan_path_to_string(lp))); |
| } |
| err.emit(); |
| } |
| |
| pub fn struct_span_err_with_code<S: Into<MultiSpan>>(&self, |
| s: S, |
| msg: &str, |
| code: DiagnosticId) |
| -> DiagnosticBuilder<'a> { |
| self.tcx.sess.struct_span_err_with_code(s, msg, code) |
| } |
| |
| pub fn span_err_with_code<S: Into<MultiSpan>>( |
| &self, |
| s: S, |
| msg: &str, |
| code: DiagnosticId, |
| ) { |
| self.tcx.sess.span_err_with_code(s, msg, code); |
| } |
| |
| fn report_bckerr(&self, err: &BckError<'tcx>) { |
| let error_span = err.span.clone(); |
| |
| match err.code { |
| err_mutbl => { |
| let descr = match err.cmt.note { |
| mc::NoteClosureEnv(_) | mc::NoteUpvarRef(_) => { |
| self.cmt_to_string(&err.cmt) |
| } |
| _ => match opt_loan_path_is_field(&err.cmt) { |
| (None, true) => { |
| format!("{} of {} binding", |
| self.cmt_to_string(&err.cmt), |
| err.cmt.mutbl.to_user_str()) |
| |
| } |
| (None, false) => { |
| format!("{} {}", |
| err.cmt.mutbl.to_user_str(), |
| self.cmt_to_string(&err.cmt)) |
| |
| } |
| (Some(lp), true) => { |
| format!("{} `{}` of {} binding", |
| self.cmt_to_string(&err.cmt), |
| self.loan_path_to_string(&lp), |
| err.cmt.mutbl.to_user_str()) |
| } |
| (Some(lp), false) => { |
| format!("{} {} `{}`", |
| err.cmt.mutbl.to_user_str(), |
| self.cmt_to_string(&err.cmt), |
| self.loan_path_to_string(&lp)) |
| } |
| } |
| }; |
| |
| let mut db = match err.cause { |
| MutabilityViolation => { |
| let mut db = self.cannot_assign(error_span, &descr, Origin::Ast); |
| if let mc::NoteClosureEnv(upvar_id) = err.cmt.note { |
| let node_id = self.tcx.hir.hir_to_node_id(upvar_id.var_id); |
| let sp = self.tcx.hir.span(node_id); |
| match self.tcx.sess.codemap().span_to_snippet(sp) { |
| Ok(snippet) => { |
| let msg = &format!("consider making `{}` mutable", snippet); |
| db.span_suggestion(sp, msg, format!("mut {}", snippet)); |
| } |
| _ => { |
| db.span_help(sp, "consider making this binding mutable"); |
| } |
| } |
| } |
| db |
| } |
| BorrowViolation(euv::ClosureCapture(_)) => { |
| self.closure_cannot_assign_to_borrowed(error_span, &descr, Origin::Ast) |
| } |
| BorrowViolation(euv::OverloadedOperator) | |
| BorrowViolation(euv::AddrOf) | |
| BorrowViolation(euv::RefBinding) | |
| BorrowViolation(euv::AutoRef) | |
| BorrowViolation(euv::AutoUnsafe) | |
| BorrowViolation(euv::ForLoop) | |
| BorrowViolation(euv::MatchDiscriminant) => { |
| self.cannot_borrow_path_as_mutable(error_span, &descr, Origin::Ast) |
| } |
| BorrowViolation(euv::ClosureInvocation) => { |
| span_bug!(err.span, |
| "err_mutbl with a closure invocation"); |
| } |
| }; |
| |
| self.note_and_explain_mutbl_error(&mut db, &err, &error_span); |
| self.note_immutability_blame(&mut db, err.cmt.immutability_blame()); |
| db.emit(); |
| } |
| err_out_of_scope(super_scope, sub_scope, cause) => { |
| let msg = match opt_loan_path(&err.cmt) { |
| None => "borrowed value".to_string(), |
| Some(lp) => { |
| format!("`{}`", self.loan_path_to_string(&lp)) |
| } |
| }; |
| |
| // When you have a borrow that lives across a yield, |
| // that reference winds up captured in the generator |
| // type. Regionck then constraints it to live as long |
| // as the generator itself. If that borrow is borrowing |
| // data owned by the generator, this winds up resulting in |
| // an `err_out_of_scope` error: |
| // |
| // ``` |
| // { |
| // let g = || { |
| // let a = &3; // this borrow is forced to ... -+ |
| // yield (); // | |
| // println!("{}", a); // | |
| // }; // | |
| // } <----------------------... live until here --------+ |
| // ``` |
| // |
| // To detect this case, we look for cases where the |
| // `super_scope` (lifetime of the value) is within the |
| // body, but the `sub_scope` is not. |
| debug!("err_out_of_scope: self.body.is_generator = {:?}", |
| self.body.is_generator); |
| let maybe_borrow_across_yield = if self.body.is_generator { |
| let body_scope = region::Scope::Node(self.body.value.hir_id.local_id); |
| debug!("err_out_of_scope: body_scope = {:?}", body_scope); |
| debug!("err_out_of_scope: super_scope = {:?}", super_scope); |
| debug!("err_out_of_scope: sub_scope = {:?}", sub_scope); |
| match (super_scope, sub_scope) { |
| (&ty::RegionKind::ReScope(value_scope), |
| &ty::RegionKind::ReScope(loan_scope)) => { |
| if { |
| // value_scope <= body_scope && |
| self.region_scope_tree.is_subscope_of(value_scope, body_scope) && |
| // body_scope <= loan_scope |
| self.region_scope_tree.is_subscope_of(body_scope, loan_scope) |
| } { |
| // We now know that this is a case |
| // that fits the bill described above: |
| // a borrow of something whose scope |
| // is within the generator, but the |
| // borrow is for a scope outside the |
| // generator. |
| // |
| // Now look within the scope of the of |
| // the value being borrowed (in the |
| // example above, that would be the |
| // block remainder that starts with |
| // `let a`) for a yield. We can cite |
| // that for the user. |
| self.region_scope_tree.yield_in_scope(value_scope) |
| } else { |
| None |
| } |
| } |
| _ => None, |
| } |
| } else { |
| None |
| }; |
| |
| if let Some((yield_span, _)) = maybe_borrow_across_yield { |
| debug!("err_out_of_scope: opt_yield_span = {:?}", yield_span); |
| self.cannot_borrow_across_generator_yield(error_span, yield_span, Origin::Ast) |
| .emit(); |
| return; |
| } |
| |
| let mut db = self.path_does_not_live_long_enough(error_span, &msg, Origin::Ast); |
| let value_kind = match err.cmt.cat { |
| mc::Categorization::Rvalue(..) => "temporary value", |
| _ => "borrowed value", |
| }; |
| |
| let is_closure = match cause { |
| euv::ClosureCapture(s) => { |
| // The primary span starts out as the closure creation point. |
| // Change the primary span here to highlight the use of the variable |
| // in the closure, because it seems more natural. Highlight |
| // closure creation point as a secondary span. |
| match db.span.primary_span() { |
| Some(primary) => { |
| db.span = MultiSpan::from_span(s); |
| db.span_label(primary, "capture occurs here"); |
| db.span_label(s, format!("{} does not live long enough", |
| value_kind)); |
| true |
| } |
| None => false |
| } |
| } |
| _ => { |
| db.span_label(error_span, format!("{} does not live long enough", |
| value_kind)); |
| false |
| } |
| }; |
| |
| let sub_span = self.region_end_span(sub_scope); |
| let super_span = self.region_end_span(super_scope); |
| |
| match (sub_span, super_span) { |
| (Some(s1), Some(s2)) if s1 == s2 => { |
| if !is_closure { |
| let msg = match opt_loan_path(&err.cmt) { |
| None => value_kind.to_string(), |
| Some(lp) => { |
| format!("`{}`", self.loan_path_to_string(&lp)) |
| } |
| }; |
| db.span_label(s1, |
| format!("{} dropped here while still borrowed", msg)); |
| } else { |
| db.span_label(s1, format!("{} dropped before borrower", value_kind)); |
| } |
| db.note("values in a scope are dropped in the opposite order \ |
| they are created"); |
| } |
| (Some(s1), Some(s2)) if !is_closure => { |
| let msg = match opt_loan_path(&err.cmt) { |
| None => value_kind.to_string(), |
| Some(lp) => { |
| format!("`{}`", self.loan_path_to_string(&lp)) |
| } |
| }; |
| db.span_label(s2, format!("{} dropped here while still borrowed", msg)); |
| db.span_label(s1, format!("{} needs to live until here", value_kind)); |
| } |
| _ => { |
| match sub_span { |
| Some(s) => { |
| db.span_label(s, format!("{} needs to live until here", |
| value_kind)); |
| } |
| None => { |
| self.tcx.note_and_explain_region( |
| &self.region_scope_tree, |
| &mut db, |
| "borrowed value must be valid for ", |
| sub_scope, |
| "..."); |
| } |
| } |
| match super_span { |
| Some(s) => { |
| db.span_label(s, format!("{} only lives until here", value_kind)); |
| } |
| None => { |
| self.tcx.note_and_explain_region( |
| &self.region_scope_tree, |
| &mut db, |
| "...but borrowed value is only valid for ", |
| super_scope, |
| ""); |
| } |
| } |
| } |
| } |
| |
| if let ty::ReScope(scope) = *super_scope { |
| let node_id = scope.node_id(self.tcx, &self.region_scope_tree); |
| match self.tcx.hir.find(node_id) { |
| Some(hir_map::NodeStmt(_)) => { |
| db.note("consider using a `let` binding to increase its lifetime"); |
| } |
| _ => {} |
| } |
| } |
| |
| db.emit(); |
| } |
| err_borrowed_pointer_too_short(loan_scope, ptr_scope) => { |
| let descr = self.cmt_to_path_or_string(&err.cmt); |
| let mut db = self.lifetime_too_short_for_reborrow(error_span, &descr, Origin::Ast); |
| let descr = match opt_loan_path(&err.cmt) { |
| Some(lp) => { |
| format!("`{}`", self.loan_path_to_string(&lp)) |
| } |
| None => self.cmt_to_string(&err.cmt), |
| }; |
| self.tcx.note_and_explain_region( |
| &self.region_scope_tree, |
| &mut db, |
| &format!("{} would have to be valid for ", |
| descr), |
| loan_scope, |
| "..."); |
| self.tcx.note_and_explain_region( |
| &self.region_scope_tree, |
| &mut db, |
| &format!("...but {} is only valid for ", descr), |
| ptr_scope, |
| ""); |
| |
| db.emit(); |
| } |
| } |
| } |
| |
| pub fn report_aliasability_violation(&self, |
| span: Span, |
| kind: AliasableViolationKind, |
| cause: mc::AliasableReason, |
| cmt: mc::cmt<'tcx>) { |
| let mut is_closure = false; |
| let prefix = match kind { |
| MutabilityViolation => { |
| "cannot assign to data" |
| } |
| BorrowViolation(euv::ClosureCapture(_)) | |
| BorrowViolation(euv::OverloadedOperator) | |
| BorrowViolation(euv::AddrOf) | |
| BorrowViolation(euv::AutoRef) | |
| BorrowViolation(euv::AutoUnsafe) | |
| BorrowViolation(euv::RefBinding) | |
| BorrowViolation(euv::MatchDiscriminant) => { |
| "cannot borrow data mutably" |
| } |
| |
| BorrowViolation(euv::ClosureInvocation) => { |
| is_closure = true; |
| "closure invocation" |
| } |
| |
| BorrowViolation(euv::ForLoop) => { |
| "`for` loop" |
| } |
| }; |
| |
| match cause { |
| mc::AliasableStatic => { |
| // This happens when we have an `&mut` or assignment to a |
| // static. We should have already reported a mutability |
| // violation first, but may have continued compiling. |
| self.tcx.sess.delay_span_bug( |
| span, |
| &format!("aliasability violation for static `{}`", prefix) |
| ); |
| return; |
| } |
| mc::AliasableStaticMut => { |
| // This path cannot occur. `static mut X` is not checked |
| // for aliasability violations. |
| span_bug!(span, "aliasability violation for static mut `{}`", prefix) |
| } |
| mc::AliasableBorrowed => {} |
| }; |
| let blame = cmt.immutability_blame(); |
| let mut err = match blame { |
| Some(ImmutabilityBlame::ClosureEnv(id)) => { |
| // FIXME: the distinction between these 2 messages looks wrong. |
| let help_msg = if let BorrowViolation(euv::ClosureCapture(_)) = kind { |
| // The aliasability violation with closure captures can |
| // happen for nested closures, so we know the enclosing |
| // closure incorrectly accepts an `Fn` while it needs to |
| // be `FnMut`. |
| "consider changing this to accept closures that implement `FnMut`" |
| |
| } else { |
| "consider changing this closure to take self by mutable reference" |
| }; |
| let node_id = self.tcx.hir.local_def_id_to_node_id(id); |
| let help_span = self.tcx.hir.span(node_id); |
| self.cannot_act_on_capture_in_sharable_fn(span, |
| prefix, |
| (help_span, help_msg), |
| Origin::Ast) |
| } |
| _ => { |
| self.cannot_assign_into_immutable_reference(span, prefix, |
| Origin::Ast) |
| } |
| }; |
| self.note_immutability_blame(&mut err, blame); |
| |
| if is_closure { |
| err.help("closures behind references must be called via `&mut`"); |
| } |
| err.emit(); |
| } |
| |
| /// Given a type, if it is an immutable reference, return a suggestion to make it mutable |
| fn suggest_mut_for_immutable(&self, pty: &hir::Ty, is_implicit_self: bool) -> Option<String> { |
| // Check wether the argument is an immutable reference |
| debug!("suggest_mut_for_immutable({:?}, {:?})", pty, is_implicit_self); |
| if let hir::TyRptr(lifetime, hir::MutTy { |
| mutbl: hir::Mutability::MutImmutable, |
| ref ty |
| }) = pty.node { |
| // Account for existing lifetimes when generating the message |
| let pointee_snippet = match self.tcx.sess.codemap().span_to_snippet(ty.span) { |
| Ok(snippet) => snippet, |
| _ => return None |
| }; |
| |
| let lifetime_snippet = if !lifetime.is_elided() { |
| format!("{} ", match self.tcx.sess.codemap().span_to_snippet(lifetime.span) { |
| Ok(lifetime_snippet) => lifetime_snippet, |
| _ => return None |
| }) |
| } else { |
| String::new() |
| }; |
| Some(format!("use `&{}mut {}` here to make mutable", |
| lifetime_snippet, |
| if is_implicit_self { "self" } else { &*pointee_snippet })) |
| } else { |
| None |
| } |
| } |
| |
| fn local_binding_mode(&self, node_id: ast::NodeId) -> ty::BindingMode { |
| let pat = match self.tcx.hir.get(node_id) { |
| hir_map::Node::NodeBinding(pat) => pat, |
| node => bug!("bad node for local: {:?}", node) |
| }; |
| |
| match pat.node { |
| hir::PatKind::Binding(..) => { |
| *self.tables |
| .pat_binding_modes() |
| .get(pat.hir_id) |
| .expect("missing binding mode") |
| } |
| _ => bug!("local is not a binding: {:?}", pat) |
| } |
| } |
| |
| fn local_ty(&self, node_id: ast::NodeId) -> (Option<&hir::Ty>, bool) { |
| let parent = self.tcx.hir.get_parent_node(node_id); |
| let parent_node = self.tcx.hir.get(parent); |
| |
| // The parent node is like a fn |
| if let Some(fn_like) = FnLikeNode::from_node(parent_node) { |
| // `nid`'s parent's `Body` |
| let fn_body = self.tcx.hir.body(fn_like.body()); |
| // Get the position of `node_id` in the arguments list |
| let arg_pos = fn_body.arguments.iter().position(|arg| arg.pat.id == node_id); |
| if let Some(i) = arg_pos { |
| // The argument's `Ty` |
| (Some(&fn_like.decl().inputs[i]), |
| i == 0 && fn_like.decl().has_implicit_self) |
| } else { |
| (None, false) |
| } |
| } else { |
| (None, false) |
| } |
| } |
| |
| fn note_immutability_blame(&self, |
| db: &mut DiagnosticBuilder, |
| blame: Option<ImmutabilityBlame>) { |
| match blame { |
| None => {} |
| Some(ImmutabilityBlame::ClosureEnv(_)) => {} |
| Some(ImmutabilityBlame::ImmLocal(node_id)) => { |
| let let_span = self.tcx.hir.span(node_id); |
| if let ty::BindByValue(..) = self.local_binding_mode(node_id) { |
| if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(let_span) { |
| let (_, is_implicit_self) = self.local_ty(node_id); |
| if is_implicit_self && snippet != "self" { |
| // avoid suggesting `mut &self`. |
| return |
| } |
| db.span_label( |
| let_span, |
| format!("consider changing this to `mut {}`", snippet) |
| ); |
| } |
| } |
| } |
| Some(ImmutabilityBlame::LocalDeref(node_id)) => { |
| let let_span = self.tcx.hir.span(node_id); |
| match self.local_binding_mode(node_id) { |
| ty::BindByReference(..) => { |
| let snippet = self.tcx.sess.codemap().span_to_snippet(let_span); |
| if let Ok(snippet) = snippet { |
| db.span_label( |
| let_span, |
| format!("consider changing this to `{}`", |
| snippet.replace("ref ", "ref mut ")) |
| ); |
| } |
| } |
| ty::BindByValue(..) => { |
| if let (Some(local_ty), is_implicit_self) = self.local_ty(node_id) { |
| if let Some(msg) = |
| self.suggest_mut_for_immutable(local_ty, is_implicit_self) { |
| db.span_label(local_ty.span, msg); |
| } |
| } |
| } |
| } |
| } |
| Some(ImmutabilityBlame::AdtFieldDeref(_, field)) => { |
| let node_id = match self.tcx.hir.as_local_node_id(field.did) { |
| Some(node_id) => node_id, |
| None => return |
| }; |
| |
| if let hir_map::Node::NodeField(ref field) = self.tcx.hir.get(node_id) { |
| if let Some(msg) = self.suggest_mut_for_immutable(&field.ty, false) { |
| db.span_label(field.ty.span, msg); |
| } |
| } |
| } |
| } |
| } |
| |
| fn report_out_of_scope_escaping_closure_capture(&self, |
| err: &BckError<'tcx>, |
| capture_span: Span) |
| { |
| let cmt_path_or_string = self.cmt_to_path_or_string(&err.cmt); |
| |
| let suggestion = |
| match self.tcx.sess.codemap().span_to_snippet(err.span) { |
| Ok(string) => format!("move {}", string), |
| Err(_) => format!("move |<args>| <body>") |
| }; |
| |
| self.cannot_capture_in_long_lived_closure(err.span, |
| &cmt_path_or_string, |
| capture_span, |
| Origin::Ast) |
| .span_suggestion(err.span, |
| &format!("to force the closure to take ownership of {} \ |
| (and any other referenced variables), \ |
| use the `move` keyword", |
| cmt_path_or_string), |
| suggestion) |
| .emit(); |
| } |
| |
| fn region_end_span(&self, region: ty::Region<'tcx>) -> Option<Span> { |
| match *region { |
| ty::ReScope(scope) => { |
| Some(scope.span(self.tcx, &self.region_scope_tree).end_point()) |
| } |
| _ => None |
| } |
| } |
| |
| fn note_and_explain_mutbl_error(&self, db: &mut DiagnosticBuilder, err: &BckError<'tcx>, |
| error_span: &Span) { |
| match err.cmt.note { |
| mc::NoteClosureEnv(upvar_id) | mc::NoteUpvarRef(upvar_id) => { |
| // If this is an `Fn` closure, it simply can't mutate upvars. |
| // If it's an `FnMut` closure, the original variable was declared immutable. |
| // We need to determine which is the case here. |
| let kind = match err.cmt.upvar().unwrap().cat { |
| Categorization::Upvar(mc::Upvar { kind, .. }) => kind, |
| _ => bug!() |
| }; |
| if kind == ty::ClosureKind::Fn { |
| let closure_node_id = |
| self.tcx.hir.local_def_id_to_node_id(upvar_id.closure_expr_id); |
| db.span_help(self.tcx.hir.span(closure_node_id), |
| "consider changing this closure to take \ |
| self by mutable reference"); |
| } |
| } |
| _ => { |
| if let Categorization::Deref(..) = err.cmt.cat { |
| db.span_label(*error_span, "cannot borrow as mutable"); |
| } else if let Categorization::Local(local_id) = err.cmt.cat { |
| let span = self.tcx.hir.span(local_id); |
| if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) { |
| if snippet.starts_with("ref mut ") || snippet.starts_with("&mut ") { |
| db.span_label(*error_span, "cannot reborrow mutably"); |
| db.span_label(*error_span, "try removing `&mut` here"); |
| } else { |
| db.span_label(*error_span, "cannot borrow mutably"); |
| } |
| } else { |
| db.span_label(*error_span, "cannot borrow mutably"); |
| } |
| } else if let Categorization::Interior(ref cmt, _) = err.cmt.cat { |
| if let mc::MutabilityCategory::McImmutable = cmt.mutbl { |
| db.span_label(*error_span, |
| "cannot mutably borrow field of immutable binding"); |
| } |
| } |
| } |
| } |
| } |
| pub fn append_loan_path_to_string(&self, |
| loan_path: &LoanPath<'tcx>, |
| out: &mut String) { |
| match loan_path.kind { |
| LpUpvar(ty::UpvarId { var_id: id, closure_expr_id: _ }) => { |
| out.push_str(&self.tcx.hir.name(self.tcx.hir.hir_to_node_id(id)).as_str()); |
| } |
| LpVar(id) => { |
| out.push_str(&self.tcx.hir.name(id).as_str()); |
| } |
| |
| LpDowncast(ref lp_base, variant_def_id) => { |
| out.push('('); |
| self.append_loan_path_to_string(&lp_base, out); |
| out.push_str(DOWNCAST_PRINTED_OPERATOR); |
| out.push_str(&self.tcx.item_path_str(variant_def_id)); |
| out.push(')'); |
| } |
| |
| LpExtend(ref lp_base, _, LpInterior(_, InteriorField(fname))) => { |
| self.append_autoderefd_loan_path_to_string(&lp_base, out); |
| match fname { |
| mc::NamedField(fname) => { |
| out.push('.'); |
| out.push_str(&fname.as_str()); |
| } |
| mc::PositionalField(idx) => { |
| out.push('.'); |
| out.push_str(&idx.to_string()); |
| } |
| } |
| } |
| |
| LpExtend(ref lp_base, _, LpInterior(_, InteriorElement)) => { |
| self.append_autoderefd_loan_path_to_string(&lp_base, out); |
| out.push_str("[..]"); |
| } |
| |
| LpExtend(ref lp_base, _, LpDeref(_)) => { |
| out.push('*'); |
| self.append_loan_path_to_string(&lp_base, out); |
| } |
| } |
| } |
| |
| pub fn append_autoderefd_loan_path_to_string(&self, |
| loan_path: &LoanPath<'tcx>, |
| out: &mut String) { |
| match loan_path.kind { |
| LpExtend(ref lp_base, _, LpDeref(_)) => { |
| // For a path like `(*x).f` or `(*x)[3]`, autoderef |
| // rules would normally allow users to omit the `*x`. |
| // So just serialize such paths to `x.f` or x[3]` respectively. |
| self.append_autoderefd_loan_path_to_string(&lp_base, out) |
| } |
| |
| LpDowncast(ref lp_base, variant_def_id) => { |
| out.push('('); |
| self.append_autoderefd_loan_path_to_string(&lp_base, out); |
| out.push_str(DOWNCAST_PRINTED_OPERATOR); |
| out.push_str(&self.tcx.item_path_str(variant_def_id)); |
| out.push(')'); |
| } |
| |
| LpVar(..) | LpUpvar(..) | LpExtend(.., LpInterior(..)) => { |
| self.append_loan_path_to_string(loan_path, out) |
| } |
| } |
| } |
| |
| pub fn loan_path_to_string(&self, loan_path: &LoanPath<'tcx>) -> String { |
| let mut result = String::new(); |
| self.append_loan_path_to_string(loan_path, &mut result); |
| result |
| } |
| |
| pub fn cmt_to_string(&self, cmt: &mc::cmt_<'tcx>) -> String { |
| cmt.descriptive_string(self.tcx) |
| } |
| |
| pub fn cmt_to_path_or_string(&self, cmt: &mc::cmt<'tcx>) -> String { |
| match opt_loan_path(cmt) { |
| Some(lp) => format!("`{}`", self.loan_path_to_string(&lp)), |
| None => self.cmt_to_string(cmt), |
| } |
| } |
| } |
| |
| impl BitwiseOperator for LoanDataFlowOperator { |
| #[inline] |
| fn join(&self, succ: usize, pred: usize) -> usize { |
| succ | pred // loans from both preds are in scope |
| } |
| } |
| |
| impl DataFlowOperator for LoanDataFlowOperator { |
| #[inline] |
| fn initial_value(&self) -> bool { |
| false // no loans in scope by default |
| } |
| } |
| |
| impl<'tcx> fmt::Debug for InteriorKind { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| match *self { |
| InteriorField(mc::NamedField(fld)) => write!(f, "{}", fld), |
| InteriorField(mc::PositionalField(i)) => write!(f, "#{}", i), |
| InteriorElement => write!(f, "[]"), |
| } |
| } |
| } |
| |
| impl<'tcx> fmt::Debug for Loan<'tcx> { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| write!(f, "Loan_{}({:?}, {:?}, {:?}-{:?}, {:?})", |
| self.index, |
| self.loan_path, |
| self.kind, |
| self.gen_scope, |
| self.kill_scope, |
| self.restricted_paths) |
| } |
| } |
| |
| impl<'tcx> fmt::Debug for LoanPath<'tcx> { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| match self.kind { |
| LpVar(id) => { |
| write!(f, "$({})", ty::tls::with(|tcx| tcx.hir.node_to_string(id))) |
| } |
| |
| LpUpvar(ty::UpvarId{ var_id, closure_expr_id }) => { |
| let s = ty::tls::with(|tcx| { |
| let var_node_id = tcx.hir.hir_to_node_id(var_id); |
| tcx.hir.node_to_string(var_node_id) |
| }); |
| write!(f, "$({} captured by id={:?})", s, closure_expr_id) |
| } |
| |
| LpDowncast(ref lp, variant_def_id) => { |
| let variant_str = if variant_def_id.is_local() { |
| ty::tls::with(|tcx| tcx.item_path_str(variant_def_id)) |
| } else { |
| format!("{:?}", variant_def_id) |
| }; |
| write!(f, "({:?}{}{})", lp, DOWNCAST_PRINTED_OPERATOR, variant_str) |
| } |
| |
| LpExtend(ref lp, _, LpDeref(_)) => { |
| write!(f, "{:?}.*", lp) |
| } |
| |
| LpExtend(ref lp, _, LpInterior(_, ref interior)) => { |
| write!(f, "{:?}.{:?}", lp, interior) |
| } |
| } |
| } |
| } |
| |
| impl<'tcx> fmt::Display for LoanPath<'tcx> { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| match self.kind { |
| LpVar(id) => { |
| write!(f, "$({})", ty::tls::with(|tcx| tcx.hir.node_to_user_string(id))) |
| } |
| |
| LpUpvar(ty::UpvarId{ var_id, closure_expr_id: _ }) => { |
| let s = ty::tls::with(|tcx| { |
| let var_node_id = tcx.hir.hir_to_node_id(var_id); |
| tcx.hir.node_to_string(var_node_id) |
| }); |
| write!(f, "$({} captured by closure)", s) |
| } |
| |
| LpDowncast(ref lp, variant_def_id) => { |
| let variant_str = if variant_def_id.is_local() { |
| ty::tls::with(|tcx| tcx.item_path_str(variant_def_id)) |
| } else { |
| format!("{:?}", variant_def_id) |
| }; |
| write!(f, "({}{}{})", lp, DOWNCAST_PRINTED_OPERATOR, variant_str) |
| } |
| |
| LpExtend(ref lp, _, LpDeref(_)) => { |
| write!(f, "{}.*", lp) |
| } |
| |
| LpExtend(ref lp, _, LpInterior(_, ref interior)) => { |
| write!(f, "{}.{:?}", lp, interior) |
| } |
| } |
| } |
| } |
