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erase regions in MIR borrowck when checking if type moves by default

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This commit is contained in:
Niko Matsakis 2017-11-06 11:52:39 -05:00
parent ef392bc11b
commit 8d3219ed5e
1 changed files with 13 additions and 4 deletions
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17
src/librustc_mir/borrow_check.rs
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@ -136,7 +136,6 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
node_id: id, node_id: id,
move_data: &mdpe.move_data, move_data: &mdpe.move_data,
param_env: param_env, param_env: param_env,
fake_infer_ctxt: &infcx,
}; };
let mut state = InProgress::new(flow_borrows, let mut state = InProgress::new(flow_borrows,
@ -154,7 +153,6 @@ pub struct MirBorrowckCtxt<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
node_id: ast::NodeId, node_id: ast::NodeId,
move_data: &'cx MoveData<'tcx>, move_data: &'cx MoveData<'tcx>,
param_env: ParamEnv<'gcx>, param_env: ParamEnv<'gcx>,
fake_infer_ctxt: &'cx InferCtxt<'cx, 'gcx, 'tcx>,
} }
// (forced to be `pub` due to its use as an associated type below.) // (forced to be `pub` due to its use as an associated type below.)
@ -592,9 +590,20 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
lvalue_span: (&Lvalue<'tcx>, Span), lvalue_span: (&Lvalue<'tcx>, Span),
flow_state: &InProgress<'cx, 'gcx, 'tcx>) { flow_state: &InProgress<'cx, 'gcx, 'tcx>) {
let lvalue = lvalue_span.0; let lvalue = lvalue_span.0;
let ty = lvalue.ty(self.mir, self.tcx).to_ty(self.tcx); let ty = lvalue.ty(self.mir, self.tcx).to_ty(self.tcx);
let moves_by_default =
self.fake_infer_ctxt.type_moves_by_default(self.param_env, ty, DUMMY_SP); // Erase the regions in type before checking whether it moves by
// default. There are a few reasons to do this:
//
// - They should not affect the result.
// - It avoids adding new region constraints into the surrounding context,
// which would trigger an ICE, since the infcx will have been "frozen" by
// the NLL region context.
let gcx = self.tcx.global_tcx();
let erased_ty = gcx.lift(&self.tcx.erase_regions(&ty)).unwrap();
let moves_by_default = erased_ty.moves_by_default(gcx, self.param_env, DUMMY_SP);
if moves_by_default { if moves_by_default {
// move of lvalue: check if this is move of already borrowed path // move of lvalue: check if this is move of already borrowed path
self.access_lvalue(context, lvalue_span, (Deep, Write(WriteKind::Move)), flow_state); self.access_lvalue(context, lvalue_span, (Deep, Write(WriteKind::Move)), flow_state);