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

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

Implementations§

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

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

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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.

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

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

Trait Implementations§

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

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type Domain = ChunkedBitSet<MovePathIndex>

The type that holds the dataflow state at any given point in the program.
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const NAME: &'static str = "maybe_uninit"

A descriptive name for this analysis. Used only for debugging. Read more
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fn bottom_value(&self, _: &Body<'tcx>) -> Self::Domain

Returns the initial value of the dataflow state upon entry to each basic block.
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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
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type Direction = Forward

The direction of this analysis. Either Forward or Backward.
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impl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>

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type Idx = MovePathIndex

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

See Analysis::apply_statement_effect.
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fn terminator_effect(
    &self,
    trans: &mut impl GenKill<Self::Idx>,
    _terminator: &Terminator<'tcx>,
    location: Location
)

See Analysis::apply_terminator_effect.
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fn call_return_effect(
    &self,
    trans: &mut impl GenKill<Self::Idx>,
    _block: BasicBlock,
    return_places: CallReturnPlaces<'_, 'tcx>
)

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

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

See Analysis::apply_before_statement_effect.
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fn before_terminator_effect(
    &self,
    _trans: &mut impl GenKill<Self::Idx>,
    _terminator: &Terminator<'tcx>,
    _location: Location
)

See Analysis::apply_before_terminator_effect.
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fn yield_resume_effect(
    &self,
    _trans: &mut impl GenKill<Self::Idx>,
    _resume_block: BasicBlock,
    _resume_place: Place<'tcx>
)

See Analysis::apply_yield_resume_effect.
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impl<'a, 'tcx> HasMoveData<'tcx> for MaybeUninitializedPlaces<'a, 'tcx>

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

Auto Trait Implementations§

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

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

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

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

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

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
    T: ?Sized,

const: unstable · source§

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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

const: unstable · 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.

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impl<'tcx, A, D> RustcPeekAt<'tcx> for Awhere
    A: Analysis<'tcx, Domain = D> + HasMoveData<'tcx>,
    D: JoinSemiLattice + Clone + BitSetExt<MovePathIndex>,

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fn peek_at(
    &self,
    tcx: TyCtxt<'tcx>,
    place: Place<'tcx>,
    flow_state: &<A as AnalysisDomain<'tcx>>::Domain,
    call: PeekCall
)

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

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

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

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere
    U: TryFrom<T>,

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

The type returned in the event of a conversion error.
const: unstable · source§

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

Performs the conversion.

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: 32 bytes