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::InteriorOffsetKind as Kind;
  20 use rustc::middle::ty;
  21
  22 use std::rc::Rc;
  23 use syntax::ast;
  24 use syntax::codemap::Span;
  25
  26 struct GatherMoveInfo<'tcx> {
  27     id: ast::NodeId,
  28     kind: MoveKind,
  29     cmt: mc::cmt<'tcx>,
  30     span_path_opt: Option<MoveSpanAndPath>
  31 }
  32
  33 pub fn gather_decl<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
  34                              move_data: &MoveData<'tcx>,
  35                              decl_id: ast::NodeId,
  36                              _decl_span: Span,
  37                              var_id: ast::NodeId) {
  38     let ty = bccx.tcx.node_id_to_type(var_id);
  39     let loan_path = Rc::new(LoanPath::new(LpVar(var_id), ty));
  40     move_data.add_move(bccx.tcx, loan_path, decl_id, Declared);
  41 }
  42
  43 pub fn gather_move_from_expr<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
  44                                        move_data: &MoveData<'tcx>,
  45                                        move_error_collector: &MoveErrorCollector<'tcx>,
  46                                        move_expr_id: ast::NodeId,
  47                                        cmt: mc::cmt<'tcx>,
  48                                        move_reason: euv::MoveReason) {
  49     let kind = match move_reason {
  50         euv::DirectRefMove | euv::PatBindingMove => MoveExpr,
  51         euv::CaptureMove => Captured
  52     };
  53     let move_info = GatherMoveInfo {
  54         id: move_expr_id,
  55         kind: kind,
  56         cmt: cmt,
  57         span_path_opt: None,
  58     };
  59     gather_move(bccx, move_data, move_error_collector, move_info);
  60 }
  61
  62 pub fn gather_match_variant<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
  63                                       move_data: &MoveData<'tcx>,
  64                                       _move_error_collector: &MoveErrorCollector<'tcx>,
  65                                       move_pat: &ast::Pat,
  66                                       cmt: mc::cmt<'tcx>,
  67                                       mode: euv::MatchMode) {
  68     let tcx = bccx.tcx;
  69     debug!("gather_match_variant(move_pat={}, cmt={:?}, mode={:?})",
  70            move_pat.id, cmt, mode);
  71
  72     let opt_lp = opt_loan_path(&cmt);
  73     match opt_lp {
  74         Some(lp) => {
  75             match lp.kind {
  76                 LpDowncast(ref base_lp, _) =>
  77                     move_data.add_variant_match(
  78                         tcx, lp.clone(), move_pat.id, base_lp.clone(), mode),
  79                 _ => panic!("should only call gather_match_variant \
  80                              for cat_downcast cmt"),
  81             }
  82         }
  83         None => {
  84             // We get None when input to match is non-path (e.g.
  85             // temporary result like a function call). Since no
  86             // loan-path is being matched, no need to record a
  87             // downcast.
  88             return;
  89         }
  90     }
  91 }
  92
  93 pub fn gather_move_from_pat<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
  94                                       move_data: &MoveData<'tcx>,
  95                                       move_error_collector: &MoveErrorCollector<'tcx>,
  96                                       move_pat: &ast::Pat,
  97                                       cmt: mc::cmt<'tcx>) {
  98     let pat_span_path_opt = match move_pat.node {
  99         ast::PatIdent(_, ref path1, _) => {
 100             Some(MoveSpanAndPath{span: move_pat.span,
 101                                  ident: path1.node})
 102         },
 103         _ => None,
 104     };
 105     let move_info = GatherMoveInfo {
 106         id: move_pat.id,
 107         kind: MovePat,
 108         cmt: cmt,
 109         span_path_opt: pat_span_path_opt,
 110     };
 111     gather_move(bccx, move_data, move_error_collector, move_info);
 112 }
 113
 114 fn gather_move<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
 115                          move_data: &MoveData<'tcx>,
 116                          move_error_collector: &MoveErrorCollector<'tcx>,
 117                          move_info: GatherMoveInfo<'tcx>) {
 118     debug!("gather_move(move_id={}, cmt={:?})",
 119            move_info.id, move_info.cmt);
 120
 121     let potentially_illegal_move =
 122                 check_and_get_illegal_move_origin(bccx, &move_info.cmt);
 123     match potentially_illegal_move {
 124         Some(illegal_move_origin) => {
 125             debug!("illegal_move_origin={:?}", illegal_move_origin);
 126             let error = MoveError::with_move_info(illegal_move_origin,
 127                                                   move_info.span_path_opt);
 128             move_error_collector.add_error(error);
 129             return
 130         }
 131         None => ()
 132     }
 133
 134     match opt_loan_path(&move_info.cmt) {
 135         Some(loan_path) => {
 136             move_data.add_move(bccx.tcx, loan_path,
 137                                move_info.id, move_info.kind);
 138         }
 139         None => {
 140             // move from rvalue or raw pointer, hence ok
 141         }
 142     }
 143 }
 144
 145 pub fn gather_assignment<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
 146                                    move_data: &MoveData<'tcx>,
 147                                    assignment_id: ast::NodeId,
 148                                    assignment_span: Span,
 149                                    assignee_loan_path: Rc<LoanPath<'tcx>>,
 150                                    assignee_id: ast::NodeId,
 151                                    mode: euv::MutateMode) {
 152     move_data.add_assignment(bccx.tcx,
 153                              assignee_loan_path,
 154                              assignment_id,
 155                              assignment_span,
 156                              assignee_id,
 157                              mode);
 158 }
 159
 160 // (keep in sync with move_error::report_cannot_move_out_of )
 161 fn check_and_get_illegal_move_origin<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>,
 162                                                cmt: &mc::cmt<'tcx>)
 163                                                -> Option<mc::cmt<'tcx>> {
 164     match cmt.cat {
 165         mc::cat_deref(_, _, mc::BorrowedPtr(..)) |
 166         mc::cat_deref(_, _, mc::Implicit(..)) |
 167         mc::cat_deref(_, _, mc::UnsafePtr(..)) |
 168         mc::cat_static_item => {
 169             Some(cmt.clone())
 170         }
 171
 172         mc::cat_rvalue(..) |
 173         mc::cat_local(..) |
 174         mc::cat_upvar(..) => {
 175             None
 176         }
 177
 178         mc::cat_downcast(ref b, _) |
 179         mc::cat_interior(ref b, mc::InteriorField(_)) |
 180         mc::cat_interior(ref b, mc::InteriorElement(Kind::Pattern, _)) => {
 181             match b.ty.sty {
 182                 ty::TyStruct(did, _) | ty::TyEnum(did, _) => {
 183                     if bccx.tcx.has_dtor(did) {
 184                         Some(cmt.clone())
 185                     } else {
 186                         check_and_get_illegal_move_origin(bccx, b)
 187                     }
 188                 }
 189                 _ => {
 190                     check_and_get_illegal_move_origin(bccx, b)
 191                 }
 192             }
 193         }
 194
 195         mc::cat_interior(_, mc::InteriorElement(Kind::Index, _)) => {
 196             // Forbid move of arr[i] for arr: [T; 3]; see RFC 533.
 197             Some(cmt.clone())
 198         }
 199
 200         mc::cat_deref(ref b, _, mc::Unique) => {
 201             check_and_get_illegal_move_origin(bccx, b)
 202         }
 203     }
 204 }