rustc_pattern_analysis::usefulness

Struct WitnessMatrix

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struct WitnessMatrix<Cx: PatCx>(Vec<WitnessStack<Cx>>);
Expand description

Represents a set of pattern-tuples that are witnesses of non-exhaustiveness for error reporting. This has similar invariants as Matrix does.

The WitnessMatrix returned by compute_exhaustiveness_and_usefulness obeys the invariant that the union of the input Matrix and the output WitnessMatrix together matches the type exhaustively.

Just as the Matrix starts with a single column, by the end of the algorithm, this has a single column, which contains the patterns that are missing for the match to be exhaustive.

Tuple Fields§

§0: Vec<WitnessStack<Cx>>

Implementations§

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impl<Cx: PatCx> WitnessMatrix<Cx>

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fn empty() -> Self

New matrix with no witnesses.

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fn unit_witness() -> Self

New matrix with one () witness, i.e. with no columns.

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fn is_empty(&self) -> bool

Whether this has any witnesses.

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fn single_column(self) -> Vec<WitnessPat<Cx>>

Asserts that there is a single column and returns the patterns in it.

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fn push_pattern(&mut self, pat: WitnessPat<Cx>)

Reverses specialization by the Missing constructor by pushing a whole new pattern.

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fn apply_constructor( &mut self, pcx: &PlaceCtxt<'_, Cx>, missing_ctors: &[Constructor<Cx>], ctor: &Constructor<Cx>, )

Reverses specialization by ctor. See the section on unspecialize at the top of the file.

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fn extend(&mut self, other: Self)

Merges the witnesses of two matrices. Their column types must match.

Trait Implementations§

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impl<Cx: PatCx> Clone for WitnessMatrix<Cx>

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fn clone(&self) -> Self

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<Cx: Debug + PatCx> Debug for WitnessMatrix<Cx>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

Auto Trait Implementations§

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impl<Cx> DynSend for WitnessMatrix<Cx>
where <Cx as PatCx>::Ty: DynSend, <Cx as PatCx>::VariantIdx: DynSend, <Cx as PatCx>::StrLit: DynSend,

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impl<Cx> DynSync for WitnessMatrix<Cx>
where <Cx as PatCx>::Ty: DynSync, <Cx as PatCx>::VariantIdx: DynSync, <Cx as PatCx>::StrLit: DynSync,

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impl<Cx> Freeze for WitnessMatrix<Cx>

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impl<Cx> RefUnwindSafe for WitnessMatrix<Cx>
where <Cx as PatCx>::Ty: RefUnwindSafe, <Cx as PatCx>::VariantIdx: RefUnwindSafe, <Cx as PatCx>::StrLit: RefUnwindSafe,

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impl<Cx> Send for WitnessMatrix<Cx>
where <Cx as PatCx>::Ty: Send, <Cx as PatCx>::VariantIdx: Send, <Cx as PatCx>::StrLit: Send,

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impl<Cx> Sync for WitnessMatrix<Cx>
where <Cx as PatCx>::Ty: Sync, <Cx as PatCx>::VariantIdx: Sync, <Cx as PatCx>::StrLit: Sync,

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impl<Cx> Unpin for WitnessMatrix<Cx>
where <Cx as PatCx>::Ty: Unpin, <Cx as PatCx>::VariantIdx: Unpin, <Cx as PatCx>::StrLit: Unpin,

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impl<Cx> UnwindSafe for WitnessMatrix<Cx>
where <Cx as PatCx>::Ty: UnwindSafe, <Cx as PatCx>::VariantIdx: UnwindSafe, <Cx as PatCx>::StrLit: UnwindSafe,

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impl<T> Aligned for T

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const ALIGN: Alignment = _

Alignment of Self.
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impl<T> Any for T
where 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 T
where T: ?Sized,

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fn borrow(&self) -> &T

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

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

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T, R> CollectAndApply<T, R> for T

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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<_>>()).

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type Output = R

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impl<T> Filterable for T

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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
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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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<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<P> IntoQueryParam<P> for P

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fn into_query_param(self) -> P

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impl<T> MaybeResult<T> for T

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type Error = !

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

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

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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same for T

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type Output = T

Should always be Self
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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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 T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<I, T, U> Upcast<I, U> for T
where U: UpcastFrom<I, T>,

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fn upcast(self, interner: I) -> U

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impl<I, T> UpcastFrom<I, T> for T

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fn upcast_from(from: T, _tcx: I) -> T

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

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fn vzip(self) -> V

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

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

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impl<T> WithSubscriber for T

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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
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<'a, T> Captures<'a> for T
where T: ?Sized,

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

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

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impl<T> MaybeSendSync for T
where T: Send + Sync,

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: 24 bytes