1.34.0[−][src]Enum std::convert::Infallible
The error type for errors that can never happen.
Since this enum has no variant, a value of this type can never actually exist.
This can be useful for generic APIs that use Result
and parameterize the error type,
to indicate that the result is always Ok
.
For example, the TryFrom
trait (conversion that returns a Result
)
has a blanket implementation for all types where a reverse Into
implementation exists.
impl<T, U> TryFrom<U> for T where U: Into<T> { type Error = Infallible; fn try_from(value: U) -> Result<Self, Infallible> { Ok(U::into(value)) // Never returns `Err` } }Run
Future compatibility
This enum has the same role as the !
“never” type,
which is unstable in this version of Rust.
When !
is stabilized, we plan to make Infallible
a type alias to it:
pub type Infallible = !;Run
… and eventually deprecate Infallible
.
However there is one case where !
syntax can be used
before !
is stabilized as a full-fleged type: in the position of a function’s return type.
Specifically, it is possible implementations for two different function pointer types:
trait MyTrait {} impl MyTrait for fn() -> ! {} impl MyTrait for fn() -> std::convert::Infallible {}Run
With Infallible
being an enum, this code is valid.
However when Infallible
becomes an alias for the never type,
the two impl
s will start to overlap
and therefore will be disallowed by the language’s trait coherence rules.
Trait Implementations
impl Debug for Infallible
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impl Eq for Infallible
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impl From<Infallible> for TryFromIntError
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fn from(x: Infallible) -> TryFromIntError
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impl From<Infallible> for TryFromSliceError
1.36.0[src]
fn from(x: Infallible) -> TryFromSliceError
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impl From<!> for Infallible
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fn from(x: !) -> Infallible
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impl Clone for Infallible
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fn clone(&self) -> Infallible
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fn clone_from(&mut self, source: &Self)
1.0.0[src]
impl PartialEq<Infallible> for Infallible
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impl PartialOrd<Infallible> for Infallible
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fn partial_cmp(&self, _other: &Infallible) -> Option<Ordering>
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#[must_use]
fn lt(&self, other: &Rhs) -> bool
1.0.0[src]
#[must_use]
fn le(&self, other: &Rhs) -> bool
1.0.0[src]
#[must_use]
fn gt(&self, other: &Rhs) -> bool
1.0.0[src]
#[must_use]
fn ge(&self, other: &Rhs) -> bool
1.0.0[src]
impl Display for Infallible
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impl Ord for Infallible
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fn cmp(&self, _other: &Infallible) -> Ordering
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fn max(self, other: Self) -> Self
1.21.0[src]
fn min(self, other: Self) -> Self
1.21.0[src]
fn clamp(self, min: Self, max: Self) -> Self
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impl Copy for Infallible
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Auto Trait Implementations
impl UnwindSafe for Infallible
impl RefUnwindSafe for Infallible
impl Unpin for Infallible
impl Send for Infallible
impl Sync for Infallible
Blanket Implementations
impl<T> From<T> for T
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
ⓘImportant traits for &'_ mut Ffn borrow_mut(&mut self) -> &mut T
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impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<T> ToString for T where
T: Display + ?Sized,
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T: Display + ?Sized,