[][src]Struct rustc_mir::dataflow::impls::MaybeUninitializedPlaces

pub struct MaybeUninitializedPlaces<'a, 'tcx> {
    tcx: TyCtxt<'tcx>,
    body: &'a Body<'tcx>,
    mdpe: &'a MoveDataParamEnv<'tcx>,
    mark_inactive_variants_as_uninit: bool,

MaybeUninitializedPlaces tracks all places that might be uninitialized upon reaching a particular point in the control flow for a function.

For example, in code like the following, we have corresponding dataflow information shown in the right-hand comments.

struct S;
fn foo(pred: bool) {                       // maybe-uninit:
                                           // {a, b, c, d}
    let a = S; let b = S; let c; let d;    // {      c, d}

    if pred {
        drop(a);                           // {a,    c, d}
        b = S;                             // {a,    c, d}

    } else {
        drop(b);                           // {   b, c, d}
        d = S;                             // {   b, c   }

    }                                      // {a, b, c, d}

    c = S;                                 // {a, b,    d}

To determine whether a place must be uninitialized at a particular control-flow point, one can take the set-difference between this data and the data from MaybeInitializedPlaces at the corresponding control-flow point.

Similarly, at a given drop statement, the set-intersection between this data and MaybeInitializedPlaces yields the set of places that would require a dynamic drop-flag at that statement.


tcx: TyCtxt<'tcx>body: &'a Body<'tcx>mdpe: &'a MoveDataParamEnv<'tcx>mark_inactive_variants_as_uninit: bool


impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx>[src]

pub fn new(
    tcx: TyCtxt<'tcx>,
    body: &'a Body<'tcx>,
    mdpe: &'a MoveDataParamEnv<'tcx>
) -> Self

pub fn mark_inactive_variants_as_uninit(self) -> Self[src]

Causes inactive enum variants to be marked as "maybe uninitialized" after a switch on an enum discriminant.

This is correct in a vacuum but is not the default because it causes problems in the borrow checker, where this information gets propagated along FakeEdges.

impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx>[src]

pub(in dataflow::impls) fn update_bits(
    trans: &mut impl GenKill<MovePathIndex>,
    path: MovePathIndex,
    state: DropFlagState

Trait Implementations

impl<'tcx, '_> AnalysisDomain<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>[src]

type Domain = BitSet<MovePathIndex>

The type that holds the dataflow state at any given point in the program.

impl<'tcx, '_> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>[src]

type Idx = MovePathIndex

impl<'a, 'tcx> HasMoveData<'tcx> for MaybeUninitializedPlaces<'a, 'tcx>[src]

Auto Trait Implementations

impl<'a, 'tcx> !RefUnwindSafe for MaybeUninitializedPlaces<'a, 'tcx>

impl<'a, 'tcx> !Send for MaybeUninitializedPlaces<'a, 'tcx>

impl<'a, 'tcx> !Sync for MaybeUninitializedPlaces<'a, 'tcx>

impl<'a, 'tcx> Unpin for MaybeUninitializedPlaces<'a, 'tcx> where
    'tcx: 'a, 

impl<'a, 'tcx> !UnwindSafe for MaybeUninitializedPlaces<'a, 'tcx>

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized

impl<T> Borrow<T> for T where
    T: ?Sized

impl<T> BorrowMut<T> for T where
    T: ?Sized

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 

impl<'tcx, A, D> RustcPeekAt<'tcx> for A where
    A: Analysis<'tcx, Domain = D> + HasMoveData<'tcx>,
    D: JoinSemiLattice + Clone + Borrow<BitSet<MovePathIndex>>, 

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> WithConstness for T[src]