rustc_pattern_analysis::usefulness

Enum Usefulness

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pub enum Usefulness<'p, Cx: PatCx> {
    Useful(Vec<(&'p DeconstructedPat<Cx>, RedundancyExplanation<'p, Cx>)>),
    Redundant(RedundancyExplanation<'p, Cx>),
}
Expand description

Indicates whether or not a given arm is useful.

Variants§

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Useful(Vec<(&'p DeconstructedPat<Cx>, RedundancyExplanation<'p, Cx>)>)

The arm is useful. This additionally carries a set of or-pattern branches that have been found to be redundant despite the overall arm being useful. Used only in the presence of or-patterns, otherwise it stays empty.

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Redundant(RedundancyExplanation<'p, Cx>)

The arm is redundant and can be removed without changing the behavior of the match expression.

Trait Implementations§

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impl<'p, Cx: Clone + PatCx> Clone for Usefulness<'p, Cx>

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fn clone(&self) -> Usefulness<'p, Cx>

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<'p, Cx: Debug + PatCx> Debug for Usefulness<'p, 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<'p, Cx> Freeze for Usefulness<'p, Cx>

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impl<'p, Cx> RefUnwindSafe for Usefulness<'p, Cx>
where <Cx as PatCx>::Ty: RefUnwindSafe, <Cx as PatCx>::PatData: RefUnwindSafe, <Cx as PatCx>::VariantIdx: RefUnwindSafe, <Cx as PatCx>::StrLit: RefUnwindSafe,

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impl<'p, Cx> Send for Usefulness<'p, Cx>
where <Cx as PatCx>::Ty: Sync, <Cx as PatCx>::PatData: Sync, <Cx as PatCx>::VariantIdx: Sync, <Cx as PatCx>::StrLit: Sync,

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impl<'p, Cx> Sync for Usefulness<'p, Cx>
where <Cx as PatCx>::Ty: Sync, <Cx as PatCx>::PatData: Sync, <Cx as PatCx>::VariantIdx: Sync, <Cx as PatCx>::StrLit: Sync,

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impl<'p, Cx> Unpin for Usefulness<'p, Cx>

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impl<'p, Cx> UnwindSafe for Usefulness<'p, Cx>
where <Cx as PatCx>::Ty: RefUnwindSafe, <Cx as PatCx>::PatData: RefUnwindSafe, <Cx as PatCx>::VariantIdx: RefUnwindSafe, <Cx as PatCx>::StrLit: RefUnwindSafe,

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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> 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

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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

Size for each variant:

  • Useful: 24 bytes
  • Redundant: 24 bytes