src/librustc_borrowck/borrowck/gather_loans/gather_moves.rs

   1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Computes moves.
  12
  13 use borrowck::*;
  14 use borrowck::gather_loans::move_error::MoveSpanAndPath;
  15 use borrowck::gather_loans::move_error::{MoveError, MoveErrorCollector};
  16 use borrowck::move_data::*;
  17 use rustc::middle::expr_use_visitor as euv;
  18 use rustc::middle::mem_categorization as mc;
  19 use rustc::middle::mem_categorization::Categorization;
  20 use rustc::middle::mem_categorization::InteriorOffsetKind as Kind;
  21 use rustc::middle::ty;
  22
  23 use std::rc::Rc;
  24 use syntax::ast;
  25 use syntax::codemap::Span;
  26 use rustc_front::hir;
  27
  28 struct GatherMoveInfo<'tcx> {
  29     id: ast::NodeId,
  30     kind: MoveKind,
  31     cmt: mc::cmt<'tcx>,
  32     span_path_opt: Option<MoveSpanAndPath>
  33 }
  34
  35 pub fn gather_decl<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
  36                              move_data: &MoveData<'tcx>,
  37                              decl_id: ast::NodeId,
  38                              _decl_span: Span,
  39                              var_id: ast::NodeId) {
  40     let ty = bccx.tcx.node_id_to_type(var_id);
  41     let loan_path = Rc::new(LoanPath::new(LpVar(var_id), ty));
  42     move_data.add_move(bccx.tcx, loan_path, decl_id, Declared);
  43 }
  44
  45 pub fn gather_move_from_expr<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
  46                                        move_data: &MoveData<'tcx>,
  47                                        move_error_collector: &mut MoveErrorCollector<'tcx>,
  48                                        move_expr_id: ast::NodeId,
  49                                        cmt: mc::cmt<'tcx>,
  50                                        move_reason: euv::MoveReason) {
  51     let kind = match move_reason {
  52         euv::DirectRefMove | euv::PatBindingMove => MoveExpr,
  53         euv::CaptureMove => Captured
  54     };
  55     let move_info = GatherMoveInfo {
  56         id: move_expr_id,
  57         kind: kind,
  58         cmt: cmt,
  59         span_path_opt: None,
  60     };
  61     gather_move(bccx, move_data, move_error_collector, move_info);
  62 }
  63
  64 pub fn gather_match_variant<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
  65                                       move_data: &MoveData<'tcx>,
  66                                       _move_error_collector: &mut MoveErrorCollector<'tcx>,
  67                                       move_pat: &hir::Pat,
  68                                       cmt: mc::cmt<'tcx>,
  69                                       mode: euv::MatchMode) {
  70     let tcx = bccx.tcx;
  71     debug!("gather_match_variant(move_pat={}, cmt={:?}, mode={:?})",
  72            move_pat.id, cmt, mode);
  73
  74     let opt_lp = opt_loan_path(&cmt);
  75     match opt_lp {
  76         Some(lp) => {
  77             match lp.kind {
  78                 LpDowncast(ref base_lp, _) =>
  79                     move_data.add_variant_match(
  80                         tcx, lp.clone(), move_pat.id, base_lp.clone(), mode),
  81                 _ => panic!("should only call gather_match_variant \
  82                              for cat_downcast cmt"),
  83             }
  84         }
  85         None => {
  86             // We get None when input to match is non-path (e.g.
  87             // temporary result like a function call). Since no
  88             // loan-path is being matched, no need to record a
  89             // downcast.
  90             return;
  91         }
  92     }
  93 }
  94
  95 pub fn gather_move_from_pat<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
  96                                       move_data: &MoveData<'tcx>,
  97                                       move_error_collector: &mut MoveErrorCollector<'tcx>,
  98                                       move_pat: &hir::Pat,
  99                                       cmt: mc::cmt<'tcx>) {
 100     let pat_span_path_opt = match move_pat.node {
 101         hir::PatIdent(_, ref path1, _) => {
 102             Some(MoveSpanAndPath{span: move_pat.span,
 103                                  name: path1.node.name})
 104         },
 105         _ => None,
 106     };
 107     let move_info = GatherMoveInfo {
 108         id: move_pat.id,
 109         kind: MovePat,
 110         cmt: cmt,
 111         span_path_opt: pat_span_path_opt,
 112     };
 113     gather_move(bccx, move_data, move_error_collector, move_info);
 114 }
 115
 116 fn gather_move<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
 117                          move_data: &MoveData<'tcx>,
 118                          move_error_collector: &mut MoveErrorCollector<'tcx>,
 119                          move_info: GatherMoveInfo<'tcx>) {
 120     debug!("gather_move(move_id={}, cmt={:?})",
 121            move_info.id, move_info.cmt);
 122
 123     let potentially_illegal_move =
 124                 check_and_get_illegal_move_origin(bccx, &move_info.cmt);
 125     match potentially_illegal_move {
 126         Some(illegal_move_origin) => {
 127             debug!("illegal_move_origin={:?}", illegal_move_origin);
 128             let error = MoveError::with_move_info(illegal_move_origin,
 129                                                   move_info.span_path_opt);
 130             move_error_collector.add_error(error);
 131             return
 132         }
 133         None => ()
 134     }
 135
 136     match opt_loan_path(&move_info.cmt) {
 137         Some(loan_path) => {
 138             move_data.add_move(bccx.tcx, loan_path,
 139                                move_info.id, move_info.kind);
 140         }
 141         None => {
 142             // move from rvalue or raw pointer, hence ok
 143         }
 144     }
 145 }
 146
 147 pub fn gather_assignment<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
 148                                    move_data: &MoveData<'tcx>,
 149                                    assignment_id: ast::NodeId,
 150                                    assignment_span: Span,
 151                                    assignee_loan_path: Rc<LoanPath<'tcx>>,
 152                                    assignee_id: ast::NodeId,
 153                                    mode: euv::MutateMode) {
 154     move_data.add_assignment(bccx.tcx,
 155                              assignee_loan_path,
 156                              assignment_id,
 157                              assignment_span,
 158                              assignee_id,
 159                              mode);
 160 }
 161
 162 // (keep in sync with move_error::report_cannot_move_out_of )
 163 fn check_and_get_illegal_move_origin<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
 164                                                cmt: &mc::cmt<'tcx>)
 165                                                -> Option<mc::cmt<'tcx>> {
 166     match cmt.cat {
 167         Categorization::Deref(_, _, mc::BorrowedPtr(..)) |
 168         Categorization::Deref(_, _, mc::Implicit(..)) |
 169         Categorization::Deref(_, _, mc::UnsafePtr(..)) |
 170         Categorization::StaticItem => {
 171             Some(cmt.clone())
 172         }
 173
 174         Categorization::Rvalue(..) |
 175         Categorization::Local(..) |
 176         Categorization::Upvar(..) => {
 177             None
 178         }
 179
 180         Categorization::Downcast(ref b, _) |
 181         Categorization::Interior(ref b, mc::InteriorField(_)) |
 182         Categorization::Interior(ref b, mc::InteriorElement(Kind::Pattern, _)) => {
 183             match b.ty.sty {
 184                 ty::TyStruct(def, _) | ty::TyEnum(def, _) => {
 185                     if def.has_dtor() {
 186                         Some(cmt.clone())
 187                     } else {
 188                         check_and_get_illegal_move_origin(bccx, b)
 189                     }
 190                 }
 191                 _ => {
 192                     check_and_get_illegal_move_origin(bccx, b)
 193                 }
 194             }
 195         }
 196
 197         Categorization::Interior(_, mc::InteriorElement(Kind::Index, _)) => {
 198             // Forbid move of arr[i] for arr: [T; 3]; see RFC 533.
 199             Some(cmt.clone())
 200         }
 201
 202         Categorization::Deref(ref b, _, mc::Unique) => {
 203             check_and_get_illegal_move_origin(bccx, b)
 204         }
 205     }
 206 }