| // Copyright 2012-2013 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. |
| |
| // ---------------------------------------------------------------------- |
| // Checking loans |
| // |
| // Phase 2 of check: we walk down the tree and check that: |
| // 1. assignments are always made to mutable locations; |
| // 2. loans made in overlapping scopes do not conflict |
| // 3. assignments do not affect things loaned out as immutable |
| // 4. moves do not affect things loaned out in any way |
| use self::UseError::*; |
| |
| use borrowck::*; |
| use borrowck::InteriorKind::{InteriorElement, InteriorField}; |
| use rustc::middle::expr_use_visitor as euv; |
| use rustc::middle::expr_use_visitor::MutateMode; |
| use rustc::middle::mem_categorization as mc; |
| use rustc::middle::mem_categorization::Categorization; |
| use rustc::middle::region; |
| use rustc::ty::{self, TyCtxt}; |
| use syntax::ast; |
| use syntax_pos::Span; |
| use rustc::hir; |
| |
| use std::rc::Rc; |
| |
| // FIXME (#16118): These functions are intended to allow the borrow checker to |
| // be less precise in its handling of Box while still allowing moves out of a |
| // Box. They should be removed when Unique is removed from LoanPath. |
| |
| fn owned_ptr_base_path<'a, 'tcx>(loan_path: &'a LoanPath<'tcx>) -> &'a LoanPath<'tcx> { |
| //! Returns the base of the leftmost dereference of an Unique in |
| //! `loan_path`. If there is no dereference of an Unique in `loan_path`, |
| //! then it just returns `loan_path` itself. |
| |
| return match helper(loan_path) { |
| Some(new_loan_path) => new_loan_path, |
| None => loan_path.clone() |
| }; |
| |
| fn helper<'a, 'tcx>(loan_path: &'a LoanPath<'tcx>) -> Option<&'a LoanPath<'tcx>> { |
| match loan_path.kind { |
| LpVar(_) | LpUpvar(_) => None, |
| LpExtend(ref lp_base, _, LpDeref(mc::Unique)) => { |
| match helper(&lp_base) { |
| v @ Some(_) => v, |
| None => Some(&lp_base) |
| } |
| } |
| LpDowncast(ref lp_base, _) | |
| LpExtend(ref lp_base, _, _) => helper(&lp_base) |
| } |
| } |
| } |
| |
| fn owned_ptr_base_path_rc<'tcx>(loan_path: &Rc<LoanPath<'tcx>>) -> Rc<LoanPath<'tcx>> { |
| //! The equivalent of `owned_ptr_base_path` for an &Rc<LoanPath> rather than |
| //! a &LoanPath. |
| |
| return match helper(loan_path) { |
| Some(new_loan_path) => new_loan_path, |
| None => loan_path.clone() |
| }; |
| |
| fn helper<'tcx>(loan_path: &Rc<LoanPath<'tcx>>) -> Option<Rc<LoanPath<'tcx>>> { |
| match loan_path.kind { |
| LpVar(_) | LpUpvar(_) => None, |
| LpExtend(ref lp_base, _, LpDeref(mc::Unique)) => { |
| match helper(lp_base) { |
| v @ Some(_) => v, |
| None => Some(lp_base.clone()) |
| } |
| } |
| LpDowncast(ref lp_base, _) | |
| LpExtend(ref lp_base, _, _) => helper(lp_base) |
| } |
| } |
| } |
| |
| struct CheckLoanCtxt<'a, 'tcx: 'a> { |
| bccx: &'a BorrowckCtxt<'a, 'tcx>, |
| dfcx_loans: &'a LoanDataFlow<'a, 'tcx>, |
| move_data: &'a move_data::FlowedMoveData<'a, 'tcx>, |
| all_loans: &'a [Loan<'tcx>], |
| param_env: &'a ty::ParameterEnvironment<'tcx>, |
| } |
| |
| impl<'a, 'tcx> euv::Delegate<'tcx> for CheckLoanCtxt<'a, 'tcx> { |
| fn consume(&mut self, |
| consume_id: ast::NodeId, |
| consume_span: Span, |
| cmt: mc::cmt<'tcx>, |
| mode: euv::ConsumeMode) { |
| debug!("consume(consume_id={}, cmt={:?}, mode={:?})", |
| consume_id, cmt, mode); |
| |
| self.consume_common(consume_id, consume_span, cmt, mode); |
| } |
| |
| fn matched_pat(&mut self, |
| _matched_pat: &hir::Pat, |
| _cmt: mc::cmt, |
| _mode: euv::MatchMode) { } |
| |
| fn consume_pat(&mut self, |
| consume_pat: &hir::Pat, |
| cmt: mc::cmt<'tcx>, |
| mode: euv::ConsumeMode) { |
| debug!("consume_pat(consume_pat={:?}, cmt={:?}, mode={:?})", |
| consume_pat, |
| cmt, |
| mode); |
| |
| self.consume_common(consume_pat.id, consume_pat.span, cmt, mode); |
| } |
| |
| fn borrow(&mut self, |
| borrow_id: ast::NodeId, |
| borrow_span: Span, |
| cmt: mc::cmt<'tcx>, |
| loan_region: ty::Region, |
| bk: ty::BorrowKind, |
| loan_cause: euv::LoanCause) |
| { |
| debug!("borrow(borrow_id={}, cmt={:?}, loan_region={:?}, \ |
| bk={:?}, loan_cause={:?})", |
| borrow_id, cmt, loan_region, |
| bk, loan_cause); |
| |
| match opt_loan_path(&cmt) { |
| Some(lp) => { |
| let moved_value_use_kind = match loan_cause { |
| euv::ClosureCapture(_) => MovedInCapture, |
| _ => MovedInUse, |
| }; |
| self.check_if_path_is_moved(borrow_id, borrow_span, moved_value_use_kind, &lp); |
| } |
| None => { } |
| } |
| |
| self.check_for_conflicting_loans(borrow_id); |
| } |
| |
| fn mutate(&mut self, |
| assignment_id: ast::NodeId, |
| assignment_span: Span, |
| assignee_cmt: mc::cmt<'tcx>, |
| mode: euv::MutateMode) |
| { |
| debug!("mutate(assignment_id={}, assignee_cmt={:?})", |
| assignment_id, assignee_cmt); |
| |
| match opt_loan_path(&assignee_cmt) { |
| Some(lp) => { |
| match mode { |
| MutateMode::Init | MutateMode::JustWrite => { |
| // In a case like `path = 1`, then path does not |
| // have to be *FULLY* initialized, but we still |
| // must be careful lest it contains derefs of |
| // pointers. |
| self.check_if_assigned_path_is_moved(assignee_cmt.id, |
| assignment_span, |
| MovedInUse, |
| &lp); |
| } |
| MutateMode::WriteAndRead => { |
| // In a case like `path += 1`, then path must be |
| // fully initialized, since we will read it before |
| // we write it. |
| self.check_if_path_is_moved(assignee_cmt.id, |
| assignment_span, |
| MovedInUse, |
| &lp); |
| } |
| } |
| } |
| None => { } |
| } |
| |
| self.check_assignment(assignment_id, assignment_span, assignee_cmt); |
| } |
| |
| fn decl_without_init(&mut self, _id: ast::NodeId, _span: Span) { } |
| } |
| |
| pub fn check_loans<'a, 'b, 'c, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>, |
| dfcx_loans: &LoanDataFlow<'b, 'tcx>, |
| move_data: &move_data::FlowedMoveData<'c, 'tcx>, |
| all_loans: &[Loan<'tcx>], |
| fn_id: ast::NodeId, |
| decl: &hir::FnDecl, |
| body: &hir::Block) { |
| debug!("check_loans(body id={})", body.id); |
| |
| let param_env = ty::ParameterEnvironment::for_item(bccx.tcx, fn_id); |
| let infcx = bccx.tcx.borrowck_fake_infer_ctxt(param_env); |
| let mut clcx = CheckLoanCtxt { |
| bccx: bccx, |
| dfcx_loans: dfcx_loans, |
| move_data: move_data, |
| all_loans: all_loans, |
| param_env: &infcx.parameter_environment |
| }; |
| euv::ExprUseVisitor::new(&mut clcx, &infcx).walk_fn(decl, body); |
| } |
| |
| #[derive(PartialEq)] |
| enum UseError<'tcx> { |
| UseOk, |
| UseWhileBorrowed(/*loan*/Rc<LoanPath<'tcx>>, /*loan*/Span) |
| } |
| |
| fn compatible_borrow_kinds(borrow_kind1: ty::BorrowKind, |
| borrow_kind2: ty::BorrowKind) |
| -> bool { |
| borrow_kind1 == ty::ImmBorrow && borrow_kind2 == ty::ImmBorrow |
| } |
| |
| impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> { |
| pub fn tcx(&self) -> TyCtxt<'a, 'tcx, 'tcx> { self.bccx.tcx } |
| |
| pub fn each_issued_loan<F>(&self, node: ast::NodeId, mut op: F) -> bool where |
| F: FnMut(&Loan<'tcx>) -> bool, |
| { |
| //! Iterates over each loan that has been issued |
| //! on entrance to `node`, regardless of whether it is |
| //! actually *in scope* at that point. Sometimes loans |
| //! are issued for future scopes and thus they may have been |
| //! *issued* but not yet be in effect. |
| |
| self.dfcx_loans.each_bit_on_entry(node, |loan_index| { |
| let loan = &self.all_loans[loan_index]; |
| op(loan) |
| }) |
| } |
| |
| pub fn each_in_scope_loan<F>(&self, scope: region::CodeExtent, mut op: F) -> bool where |
| F: FnMut(&Loan<'tcx>) -> bool, |
| { |
| //! Like `each_issued_loan()`, but only considers loans that are |
| //! currently in scope. |
| |
| let tcx = self.tcx(); |
| self.each_issued_loan(scope.node_id(&tcx.region_maps), |loan| { |
| if tcx.region_maps.is_subscope_of(scope, loan.kill_scope) { |
| op(loan) |
| } else { |
| true |
| } |
| }) |
| } |
| |
| fn each_in_scope_loan_affecting_path<F>(&self, |
| scope: region::CodeExtent, |
| loan_path: &LoanPath<'tcx>, |
| mut op: F) |
| -> bool where |
| F: FnMut(&Loan<'tcx>) -> bool, |
| { |
| //! Iterates through all of the in-scope loans affecting `loan_path`, |
| //! calling `op`, and ceasing iteration if `false` is returned. |
| |
| // First, we check for a loan restricting the path P being used. This |
| // accounts for borrows of P but also borrows of subpaths, like P.a.b. |
| // Consider the following example: |
| // |
| // let x = &mut a.b.c; // Restricts a, a.b, and a.b.c |
| // let y = a; // Conflicts with restriction |
| |
| let loan_path = owned_ptr_base_path(loan_path); |
| let cont = self.each_in_scope_loan(scope, |loan| { |
| let mut ret = true; |
| for restr_path in &loan.restricted_paths { |
| if **restr_path == *loan_path { |
| if !op(loan) { |
| ret = false; |
| break; |
| } |
| } |
| } |
| ret |
| }); |
| |
| if !cont { |
| return false; |
| } |
| |
| // Next, we must check for *loans* (not restrictions) on the path P or |
| // any base path. This rejects examples like the following: |
| // |
| // let x = &mut a.b; |
| // let y = a.b.c; |
| // |
| // Limiting this search to *loans* and not *restrictions* means that |
| // examples like the following continue to work: |
| // |
| // let x = &mut a.b; |
| // let y = a.c; |
| |
| let mut loan_path = loan_path; |
| loop { |
| match loan_path.kind { |
| LpVar(_) | LpUpvar(_) => { |
| break; |
| } |
| LpDowncast(ref lp_base, _) | |
| LpExtend(ref lp_base, _, _) => { |
| loan_path = &lp_base; |
| } |
| } |
| |
| let cont = self.each_in_scope_loan(scope, |loan| { |
| if *loan.loan_path == *loan_path { |
| op(loan) |
| } else { |
| true |
| } |
| }); |
| |
| if !cont { |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| pub fn loans_generated_by(&self, node: ast::NodeId) -> Vec<usize> { |
| //! Returns a vector of the loans that are generated as |
| //! we enter `node`. |
| |
| let mut result = Vec::new(); |
| self.dfcx_loans.each_gen_bit(node, |loan_index| { |
| result.push(loan_index); |
| true |
| }); |
| return result; |
| } |
| |
| pub fn check_for_conflicting_loans(&self, node: ast::NodeId) { |
| //! Checks to see whether any of the loans that are issued |
| //! on entrance to `node` conflict with loans that have already been |
| //! issued when we enter `node` (for example, we do not |
| //! permit two `&mut` borrows of the same variable). |
| //! |
| //! (Note that some loans can be *issued* without necessarily |
| //! taking effect yet.) |
| |
| debug!("check_for_conflicting_loans(node={:?})", node); |
| |
| let new_loan_indices = self.loans_generated_by(node); |
| debug!("new_loan_indices = {:?}", new_loan_indices); |
| |
| for &new_loan_index in &new_loan_indices { |
| self.each_issued_loan(node, |issued_loan| { |
| let new_loan = &self.all_loans[new_loan_index]; |
| // Only report an error for the first issued loan that conflicts |
| // to avoid O(n^2) errors. |
| self.report_error_if_loans_conflict(issued_loan, new_loan) |
| }); |
| } |
| |
| for (i, &x) in new_loan_indices.iter().enumerate() { |
| let old_loan = &self.all_loans[x]; |
| for &y in &new_loan_indices[(i+1) ..] { |
| let new_loan = &self.all_loans[y]; |
| self.report_error_if_loans_conflict(old_loan, new_loan); |
| } |
| } |
| } |
| |
| pub fn report_error_if_loans_conflict(&self, |
| old_loan: &Loan<'tcx>, |
| new_loan: &Loan<'tcx>) |
| -> bool { |
| //! Checks whether `old_loan` and `new_loan` can safely be issued |
| //! simultaneously. |
| |
| debug!("report_error_if_loans_conflict(old_loan={:?}, new_loan={:?})", |
| old_loan, |
| new_loan); |
| |
| // Should only be called for loans that are in scope at the same time. |
| assert!(self.tcx().region_maps.scopes_intersect(old_loan.kill_scope, |
| new_loan.kill_scope)); |
| |
| self.report_error_if_loan_conflicts_with_restriction( |
| old_loan, new_loan, old_loan, new_loan) && |
| self.report_error_if_loan_conflicts_with_restriction( |
| new_loan, old_loan, old_loan, new_loan) |
| } |
| |
| pub fn report_error_if_loan_conflicts_with_restriction(&self, |
| loan1: &Loan<'tcx>, |
| loan2: &Loan<'tcx>, |
| old_loan: &Loan<'tcx>, |
| new_loan: &Loan<'tcx>) |
| -> bool { |
| //! Checks whether the restrictions introduced by `loan1` would |
| //! prohibit `loan2`. Returns false if an error is reported. |
| |
| debug!("report_error_if_loan_conflicts_with_restriction(\ |
| loan1={:?}, loan2={:?})", |
| loan1, |
| loan2); |
| |
| if compatible_borrow_kinds(loan1.kind, loan2.kind) { |
| return true; |
| } |
| |
| let loan2_base_path = owned_ptr_base_path_rc(&loan2.loan_path); |
| for restr_path in &loan1.restricted_paths { |
| if *restr_path != loan2_base_path { continue; } |
| |
| // If new_loan is something like `x.a`, and old_loan is something like `x.b`, we would |
| // normally generate a rather confusing message (in this case, for multiple mutable |
| // borrows): |
| // |
| // error: cannot borrow `x.b` as mutable more than once at a time |
| // note: previous borrow of `x.a` occurs here; the mutable borrow prevents |
| // subsequent moves, borrows, or modification of `x.a` until the borrow ends |
| // |
| // What we want to do instead is get the 'common ancestor' of the two borrow paths and |
| // use that for most of the message instead, giving is something like this: |
| // |
| // error: cannot borrow `x` as mutable more than once at a time |
| // note: previous borrow of `x` occurs here (through borrowing `x.a`); the mutable |
| // borrow prevents subsequent moves, borrows, or modification of `x` until the |
| // borrow ends |
| |
| let common = new_loan.loan_path.common(&old_loan.loan_path); |
| let (nl, ol, new_loan_msg, old_loan_msg) = { |
| if new_loan.loan_path.has_fork(&old_loan.loan_path) && common.is_some() { |
| let nl = self.bccx.loan_path_to_string(&common.unwrap()); |
| let ol = nl.clone(); |
| let new_loan_msg = format!(" (via `{}`)", |
| self.bccx.loan_path_to_string( |
| &new_loan.loan_path)); |
| let old_loan_msg = format!(" (via `{}`)", |
| self.bccx.loan_path_to_string( |
| &old_loan.loan_path)); |
| (nl, ol, new_loan_msg, old_loan_msg) |
| } else { |
| (self.bccx.loan_path_to_string(&new_loan.loan_path), |
| self.bccx.loan_path_to_string(&old_loan.loan_path), |
| String::new(), |
| String::new()) |
| } |
| }; |
| |
| let ol_pronoun = if new_loan.loan_path == old_loan.loan_path { |
| "it".to_string() |
| } else { |
| format!("`{}`", ol) |
| }; |
| |
| // We want to assemble all the relevant locations for the error. |
| // |
| // 1. Where did the new loan occur. |
| // - if due to closure creation, where was the variable used in closure? |
| // 2. Where did old loan occur. |
| // 3. Where does old loan expire. |
| |
| let previous_end_span = |
| self.tcx().map.span(old_loan.kill_scope.node_id(&self.tcx().region_maps)) |
| .end_point(); |
| |
| let mut err = match (new_loan.kind, old_loan.kind) { |
| (ty::MutBorrow, ty::MutBorrow) => { |
| let mut err = struct_span_err!(self.bccx, new_loan.span, E0499, |
| "cannot borrow `{}`{} as mutable \ |
| more than once at a time", |
| nl, new_loan_msg); |
| err.span_label( |
| old_loan.span, |
| &format!("first mutable borrow occurs here{}", old_loan_msg)); |
| err.span_label( |
| new_loan.span, |
| &format!("second mutable borrow occurs here{}", new_loan_msg)); |
| err.span_label( |
| previous_end_span, |
| &format!("first borrow ends here")); |
| err |
| } |
| |
| (ty::UniqueImmBorrow, ty::UniqueImmBorrow) => { |
| let mut err = struct_span_err!(self.bccx, new_loan.span, E0524, |
| "two closures require unique access to `{}` \ |
| at the same time", |
| nl); |
| err.span_label( |
| old_loan.span, |
| &format!("first closure is constructed here")); |
| err.span_label( |
| new_loan.span, |
| &format!("second closure is constructed here")); |
| err.span_label( |
| previous_end_span, |
| &format!("borrow from first closure ends here")); |
| err |
| } |
| |
| (ty::UniqueImmBorrow, _) => { |
| let mut err = struct_span_err!(self.bccx, new_loan.span, E0500, |
| "closure requires unique access to `{}` \ |
| but {} is already borrowed{}", |
| nl, ol_pronoun, old_loan_msg); |
| err.span_label( |
| new_loan.span, |
| &format!("closure construction occurs here{}", new_loan_msg)); |
| err.span_label( |
| old_loan.span, |
| &format!("borrow occurs here{}", old_loan_msg)); |
| err.span_label( |
| previous_end_span, |
| &format!("borrow ends here")); |
| err |
| } |
| |
| (_, ty::UniqueImmBorrow) => { |
| let mut err = struct_span_err!(self.bccx, new_loan.span, E0501, |
| "cannot borrow `{}`{} as {} because \ |
| previous closure requires unique access", |
| nl, new_loan_msg, new_loan.kind.to_user_str()); |
| err.span_label( |
| new_loan.span, |
| &format!("borrow occurs here{}", new_loan_msg)); |
| err.span_label( |
| old_loan.span, |
| &format!("closure construction occurs here{}", old_loan_msg)); |
| err.span_label( |
| previous_end_span, |
| &format!("borrow from closure ends here")); |
| err |
| } |
| |
| (_, _) => { |
| let mut err = struct_span_err!(self.bccx, new_loan.span, E0502, |
| "cannot borrow `{}`{} as {} because \ |
| {} is also borrowed as {}{}", |
| nl, |
| new_loan_msg, |
| new_loan.kind.to_user_str(), |
| ol_pronoun, |
| old_loan.kind.to_user_str(), |
| old_loan_msg); |
| err.span_label( |
| new_loan.span, |
| &format!("{} borrow occurs here{}", |
| new_loan.kind.to_user_str(), |
| new_loan_msg)); |
| err.span_label( |
| old_loan.span, |
| &format!("{} borrow occurs here{}", |
| old_loan.kind.to_user_str(), |
| old_loan_msg)); |
| err.span_label( |
| previous_end_span, |
| &format!("{} borrow ends here", |
| old_loan.kind.to_user_str())); |
| err |
| } |
| }; |
| |
| match new_loan.cause { |
| euv::ClosureCapture(span) => { |
| err.span_label( |
| span, |
| &format!("borrow occurs due to use of `{}` in closure", nl)); |
| } |
| _ => { } |
| } |
| |
| match old_loan.cause { |
| euv::ClosureCapture(span) => { |
| err.span_label( |
| span, |
| &format!("previous borrow occurs due to use of `{}` in closure", |
| ol)); |
| } |
| _ => { } |
| } |
| |
| err.emit(); |
| return false; |
| } |
| |
| true |
| } |
| |
| fn consume_common(&self, |
| id: ast::NodeId, |
| span: Span, |
| cmt: mc::cmt<'tcx>, |
| mode: euv::ConsumeMode) { |
| match opt_loan_path(&cmt) { |
| Some(lp) => { |
| let moved_value_use_kind = match mode { |
| euv::Copy => { |
| self.check_for_copy_of_frozen_path(id, span, &lp); |
| MovedInUse |
| } |
| euv::Move(_) => { |
| match self.move_data.kind_of_move_of_path(id, &lp) { |
| None => { |
| // Sometimes moves don't have a move kind; |
| // this either means that the original move |
| // was from something illegal to move, |
| // or was moved from referent of an unsafe |
| // pointer or something like that. |
| MovedInUse |
| } |
| Some(move_kind) => { |
| self.check_for_move_of_borrowed_path(id, span, |
| &lp, move_kind); |
| if move_kind == move_data::Captured { |
| MovedInCapture |
| } else { |
| MovedInUse |
| } |
| } |
| } |
| } |
| }; |
| |
| self.check_if_path_is_moved(id, span, moved_value_use_kind, &lp); |
| } |
| None => { } |
| } |
| } |
| |
| fn check_for_copy_of_frozen_path(&self, |
| id: ast::NodeId, |
| span: Span, |
| copy_path: &LoanPath<'tcx>) { |
| match self.analyze_restrictions_on_use(id, copy_path, ty::ImmBorrow) { |
| UseOk => { } |
| UseWhileBorrowed(loan_path, loan_span) => { |
| struct_span_err!(self.bccx, span, E0503, |
| "cannot use `{}` because it was mutably borrowed", |
| &self.bccx.loan_path_to_string(copy_path)) |
| .span_note(loan_span, |
| &format!("borrow of `{}` occurs here", |
| &self.bccx.loan_path_to_string(&loan_path)) |
| ) |
| .emit(); |
| } |
| } |
| } |
| |
| fn check_for_move_of_borrowed_path(&self, |
| id: ast::NodeId, |
| span: Span, |
| move_path: &LoanPath<'tcx>, |
| move_kind: move_data::MoveKind) { |
| // We want to detect if there are any loans at all, so we search for |
| // any loans incompatible with MutBorrrow, since all other kinds of |
| // loans are incompatible with that. |
| match self.analyze_restrictions_on_use(id, move_path, ty::MutBorrow) { |
| UseOk => { } |
| UseWhileBorrowed(loan_path, loan_span) => { |
| let mut err = match move_kind { |
| move_data::Captured => { |
| let mut err = struct_span_err!(self.bccx, span, E0504, |
| "cannot move `{}` into closure because it is borrowed", |
| &self.bccx.loan_path_to_string(move_path)); |
| err.span_label( |
| loan_span, |
| &format!("borrow of `{}` occurs here", |
| &self.bccx.loan_path_to_string(&loan_path)) |
| ); |
| err.span_label( |
| span, |
| &format!("move into closure occurs here") |
| ); |
| err |
| } |
| move_data::Declared | |
| move_data::MoveExpr | |
| move_data::MovePat => { |
| let mut err = struct_span_err!(self.bccx, span, E0505, |
| "cannot move out of `{}` because it is borrowed", |
| &self.bccx.loan_path_to_string(move_path)); |
| err.span_label( |
| loan_span, |
| &format!("borrow of `{}` occurs here", |
| &self.bccx.loan_path_to_string(&loan_path)) |
| ); |
| err.span_label( |
| span, |
| &format!("move out of `{}` occurs here", |
| &self.bccx.loan_path_to_string(move_path)) |
| ); |
| err |
| } |
| }; |
| |
| err.emit(); |
| } |
| } |
| } |
| |
| pub fn analyze_restrictions_on_use(&self, |
| expr_id: ast::NodeId, |
| use_path: &LoanPath<'tcx>, |
| borrow_kind: ty::BorrowKind) |
| -> UseError<'tcx> { |
| debug!("analyze_restrictions_on_use(expr_id={}, use_path={:?})", |
| self.tcx().map.node_to_string(expr_id), |
| use_path); |
| |
| let mut ret = UseOk; |
| |
| self.each_in_scope_loan_affecting_path( |
| self.tcx().region_maps.node_extent(expr_id), use_path, |loan| { |
| if !compatible_borrow_kinds(loan.kind, borrow_kind) { |
| ret = UseWhileBorrowed(loan.loan_path.clone(), loan.span); |
| false |
| } else { |
| true |
| } |
| }); |
| |
| return ret; |
| } |
| |
| /// Reports an error if `expr` (which should be a path) |
| /// is using a moved/uninitialized value |
| fn check_if_path_is_moved(&self, |
| id: ast::NodeId, |
| span: Span, |
| use_kind: MovedValueUseKind, |
| lp: &Rc<LoanPath<'tcx>>) { |
| debug!("check_if_path_is_moved(id={}, use_kind={:?}, lp={:?})", |
| id, use_kind, lp); |
| |
| // FIXME (22079): if you find yourself tempted to cut and paste |
| // the body below and then specializing the error reporting, |
| // consider refactoring this instead! |
| |
| let base_lp = owned_ptr_base_path_rc(lp); |
| self.move_data.each_move_of(id, &base_lp, |the_move, moved_lp| { |
| self.bccx.report_use_of_moved_value( |
| span, |
| use_kind, |
| &lp, |
| the_move, |
| moved_lp, |
| self.param_env); |
| false |
| }); |
| } |
| |
| /// Reports an error if assigning to `lp` will use a |
| /// moved/uninitialized value. Mainly this is concerned with |
| /// detecting derefs of uninitialized pointers. |
| /// |
| /// For example: |
| /// |
| /// ```ignore |
| /// let a: i32; |
| /// a = 10; // ok, even though a is uninitialized |
| /// |
| /// struct Point { x: u32, y: u32 } |
| /// let p: Point; |
| /// p.x = 22; // ok, even though `p` is uninitialized |
| /// |
| /// let p: Box<Point>; |
| /// (*p).x = 22; // not ok, p is uninitialized, can't deref |
| /// ``` |
| fn check_if_assigned_path_is_moved(&self, |
| id: ast::NodeId, |
| span: Span, |
| use_kind: MovedValueUseKind, |
| lp: &Rc<LoanPath<'tcx>>) |
| { |
| match lp.kind { |
| LpVar(_) | LpUpvar(_) => { |
| // assigning to `x` does not require that `x` is initialized |
| } |
| LpDowncast(ref lp_base, _) => { |
| // assigning to `(P->Variant).f` is ok if assigning to `P` is ok |
| self.check_if_assigned_path_is_moved(id, span, |
| use_kind, lp_base); |
| } |
| LpExtend(ref lp_base, _, LpInterior(_, InteriorField(_))) => { |
| match lp_base.to_type().sty { |
| ty::TyStruct(def, _) | ty::TyEnum(def, _) if def.has_dtor() => { |
| // In the case where the owner implements drop, then |
| // the path must be initialized to prevent a case of |
| // partial reinitialization |
| // |
| // FIXME (22079): could refactor via hypothetical |
| // generalized check_if_path_is_moved |
| let loan_path = owned_ptr_base_path_rc(lp_base); |
| self.move_data.each_move_of(id, &loan_path, |_, _| { |
| self.bccx |
| .report_partial_reinitialization_of_uninitialized_structure( |
| span, |
| &loan_path); |
| false |
| }); |
| return; |
| }, |
| _ => {}, |
| } |
| |
| // assigning to `P.f` is ok if assigning to `P` is ok |
| self.check_if_assigned_path_is_moved(id, span, |
| use_kind, lp_base); |
| } |
| LpExtend(ref lp_base, _, LpInterior(_, InteriorElement(..))) | |
| LpExtend(ref lp_base, _, LpDeref(_)) => { |
| // assigning to `P[i]` requires `P` is initialized |
| // assigning to `(*P)` requires `P` is initialized |
| self.check_if_path_is_moved(id, span, use_kind, lp_base); |
| } |
| } |
| } |
| |
| fn check_assignment(&self, |
| assignment_id: ast::NodeId, |
| assignment_span: Span, |
| assignee_cmt: mc::cmt<'tcx>) { |
| debug!("check_assignment(assignee_cmt={:?})", assignee_cmt); |
| |
| // Check that we don't invalidate any outstanding loans |
| if let Some(loan_path) = opt_loan_path(&assignee_cmt) { |
| let scope = self.tcx().region_maps.node_extent(assignment_id); |
| self.each_in_scope_loan_affecting_path(scope, &loan_path, |loan| { |
| self.report_illegal_mutation(assignment_span, &loan_path, loan); |
| false |
| }); |
| } |
| |
| // Check for reassignments to (immutable) local variables. This |
| // needs to be done here instead of in check_loans because we |
| // depend on move data. |
| if let Categorization::Local(local_id) = assignee_cmt.cat { |
| let lp = opt_loan_path(&assignee_cmt).unwrap(); |
| self.move_data.each_assignment_of(assignment_id, &lp, |assign| { |
| if assignee_cmt.mutbl.is_mutable() { |
| self.tcx().used_mut_nodes.borrow_mut().insert(local_id); |
| } else { |
| self.bccx.report_reassigned_immutable_variable( |
| assignment_span, |
| &lp, |
| assign); |
| } |
| false |
| }); |
| return |
| } |
| } |
| |
| pub fn report_illegal_mutation(&self, |
| span: Span, |
| loan_path: &LoanPath<'tcx>, |
| loan: &Loan) { |
| struct_span_err!(self.bccx, span, E0506, |
| "cannot assign to `{}` because it is borrowed", |
| self.bccx.loan_path_to_string(loan_path)) |
| .span_label(loan.span, |
| &format!("borrow of `{}` occurs here", |
| self.bccx.loan_path_to_string(loan_path))) |
| .span_label(span, |
| &format!("assignment to borrowed `{}` occurs here", |
| self.bccx.loan_path_to_string(loan_path))) |
| .emit(); |
| } |
| } |
