pub struct MaybeUninitializedPlaces<'a, 'tcx> {
    tcx: TyCtxt<'tcx>,
    body: &'a Body<'tcx>,
    mdpe: &'a MoveDataParamEnv<'tcx>,
    mark_inactive_variants_as_uninit: bool,
    skip_unreachable_unwind: BitSet<BasicBlock>,
}
Expand description

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 mut 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.

Fields§

§tcx: TyCtxt<'tcx>§body: &'a Body<'tcx>§mdpe: &'a MoveDataParamEnv<'tcx>§mark_inactive_variants_as_uninit: bool§skip_unreachable_unwind: BitSet<BasicBlock>

Implementations§

source§

impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx>

source

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

source

pub fn mark_inactive_variants_as_uninit(self) -> Self

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.

source

pub fn skipping_unreachable_unwind( self, unreachable_unwind: BitSet<BasicBlock> ) -> Self

source§

impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx>

source

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

Trait Implementations§

source§

impl<'tcx> AnalysisDomain<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>

§

type Domain = ChunkedBitSet<MovePathIndex>

There can be many more MovePathIndex than there are locals in a MIR body. We use a chunked bitset to avoid paying too high a memory footprint.

source§

const NAME: &'static str = "maybe_uninit"

A descriptive name for this analysis. Used only for debugging. Read more
source§

fn bottom_value(&self, _: &Body<'tcx>) -> Self::Domain

Returns the initial value of the dataflow state upon entry to each basic block.
source§

fn initialize_start_block(&self, _: &Body<'tcx>, state: &mut Self::Domain)

Mutates the initial value of the dataflow state upon entry to the START_BLOCK. Read more
§

type Direction = Forward

The direction of this analysis. Either Forward or Backward.
source§

impl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>

§

type Idx = MovePathIndex

source§

fn domain_size(&self, _: &Body<'tcx>) -> usize

source§

fn statement_effect( &mut self, trans: &mut impl GenKill<Self::Idx>, _statement: &Statement<'tcx>, location: Location )

See Analysis::apply_statement_effect. Note how the second arg differs.
source§

fn terminator_effect<'mir>( &mut self, trans: &mut Self::Domain, terminator: &'mir Terminator<'tcx>, location: Location ) -> TerminatorEdges<'mir, 'tcx>

See Analysis::apply_terminator_effect.
source§

fn call_return_effect( &mut self, trans: &mut Self::Domain, _block: BasicBlock, return_places: CallReturnPlaces<'_, 'tcx> )

See Analysis::apply_call_return_effect.
source§

fn switch_int_edge_effects<G: GenKill<Self::Idx>>( &mut self, block: BasicBlock, discr: &Operand<'tcx>, edge_effects: &mut impl SwitchIntEdgeEffects<G> )

See Analysis::apply_switch_int_edge_effects.
source§

fn before_statement_effect( &mut self, _trans: &mut impl GenKill<Self::Idx>, _statement: &Statement<'tcx>, _location: Location )

See Analysis::apply_before_statement_effect. Note how the second arg differs.
source§

fn before_terminator_effect( &mut self, _trans: &mut Self::Domain, _terminator: &Terminator<'tcx>, _location: Location )

See Analysis::apply_before_terminator_effect.
source§

impl<'a, 'tcx> HasMoveData<'tcx> for MaybeUninitializedPlaces<'a, 'tcx>

source§

fn move_data(&self) -> &MoveData<'tcx>

Auto Trait Implementations§

§

impl<'a, 'tcx> DynSend for MaybeUninitializedPlaces<'a, 'tcx>

§

impl<'a, 'tcx> DynSync for MaybeUninitializedPlaces<'a, 'tcx>

§

impl<'a, 'tcx> Freeze for MaybeUninitializedPlaces<'a, 'tcx>

§

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>

§

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

Blanket Implementations§

source§

impl<T> Aligned for T

source§

const ALIGN: Alignment = _

Alignment of Self.
source§

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

source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
source§

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

source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
source§

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

source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
source§

impl<T, R> CollectAndApply<T, R> for T

source§

fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to f(&iter.collect::<Vec<_>>()).

§

type Output = R

source§

impl<T> Filterable for T

source§

fn filterable( self, filter_name: &'static str ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. Read more
source§

impl<T> From<T> for T

source§

fn from(t: T) -> T

Returns the argument unchanged.

source§

impl<T> Instrument for T

source§

fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
source§

fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
source§

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

source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

source§

impl<P> IntoQueryParam<P> for P

source§

impl<T> MaybeResult<T> for T

§

type Error = !

source§

fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

source§

fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

source§

impl<T> Pointable for T

source§

const ALIGN: usize = _

The alignment of pointer.
§

type Init = T

The type for initializers.
source§

unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
source§

unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
source§

unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
source§

unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
source§

impl<T> Same for T

§

type Output = T

Should always be Self
source§

impl<'tcx, T> ToPredicate<'tcx, T> for T

source§

fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T

source§

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

§

type Error = Infallible

The type returned in the event of a conversion error.
source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
source§

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.
source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
source§

impl<V, T> VZip<V> for T
where V: MultiLane<T>,

source§

fn vzip(self) -> V

source§

impl<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

source§

default fn from_cycle_error( tcx: Tcx, cycle_error: &CycleError, _guar: ErrorGuaranteed ) -> T

source§

impl<T> WithSubscriber for T

source§

fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
source§

fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
source§

impl<'a, T> Captures<'a> for T
where T: ?Sized,

source§

impl<T> ErasedDestructor for T
where T: 'static,

Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 64 bytes