1 //! The move-analysis portion of borrowck needs to work in an abstract
2 //! domain of lifted `Place`s. Most of the `Place` variants fall into a
3 //! one-to-one mapping between the concrete and abstract (e.g., a
4 //! field-deref on a local variable, `x.field`, has the same meaning
5 //! in both domains). Indexed projections are the exception: `a[x]`
6 //! needs to be treated as mapping to the same move path as `a[y]` as
7 //! well as `a[13]`, etc.
9 //! (In theory, the analysis could be extended to work with sets of
10 //! paths, so that `a[0]` and `a[13]` could be kept distinct, while
11 //! `a[x]` would still overlap them both. But that is not this
12 //! representation does today.)
14 use rustc_middle::mir::{Local, Operand, PlaceElem, ProjectionElem};
15 use rustc_middle::ty::Ty;
17 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
18 pub struct AbstractOperand;
19 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
20 pub struct AbstractType;
21 pub type AbstractElem = ProjectionElem<AbstractOperand, AbstractType>;
25 fn lift(&self) -> Self::Abstract;
27 impl<'tcx> Lift for Operand<'tcx> {
28 type Abstract = AbstractOperand;
29 fn lift(&self) -> Self::Abstract {
34 type Abstract = AbstractOperand;
35 fn lift(&self) -> Self::Abstract {
39 impl<'tcx> Lift for Ty<'tcx> {
40 type Abstract = AbstractType;
41 fn lift(&self) -> Self::Abstract {
45 impl<'tcx> Lift for PlaceElem<'tcx> {
46 type Abstract = AbstractElem;
47 fn lift(&self) -> Self::Abstract {
49 ProjectionElem::Deref => ProjectionElem::Deref,
50 ProjectionElem::Field(f, ty) => ProjectionElem::Field(f, ty.lift()),
51 ProjectionElem::Index(ref i) => ProjectionElem::Index(i.lift()),
52 ProjectionElem::Subslice { from, to, from_end } => {
53 ProjectionElem::Subslice { from, to, from_end }
55 ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
56 ProjectionElem::ConstantIndex { offset, min_length, from_end }
58 ProjectionElem::Downcast(a, u) => ProjectionElem::Downcast(a, u),