# Enum core::convert::Infallible
1.34.0[−][src]

    pub enum 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`
        }
    }

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# 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 = !;

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… and eventually deprecate `Infallible`.

However there is one case where `!` syntax can be used before `!` is stabilized as a full-fledged 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 {}

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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 Clone for Infallible`[src]

#### `fn clone(&self) -> Infallible`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`1.0.0[src]

Performs copy-assignment from `source`. Read more

### `impl Debug for Infallible`[src]

#### `fn fmt(&self, _: &mut Formatter<'_>) -> Result`[src]

Formats the value using the given formatter. Read more

### `impl Display for Infallible`[src]

#### `fn fmt(&self, _: &mut Formatter<'_>) -> Result`[src]

Formats the value using the given formatter. Read more

### `impl From<!> for Infallible`[src]

#### `fn from(x: !) -> Self`[src]

Performs the conversion.

### `impl From<Infallible> for TryFromIntError`[src]

#### `fn from(x: Infallible) -> TryFromIntError`[src]

Performs the conversion.

### `impl From<Infallible> for TryFromSliceError` 1.36.0[src]

#### `fn from(x: Infallible) -> TryFromSliceError`[src]

Performs the conversion.

### `impl Hash for Infallible` 1.44.0[src]

#### `fn hash<H: Hasher>(&self, _: &mut H)`[src]

Feeds this value into the given `Hasher`. Read more

#### `fn hash_slice<H: Hasher>(data: &[Self], state: &mut H) where
Self: Sized,` 1.3.0[src]

Feeds a slice of this type into the given `Hasher`. Read more

### `impl Ord for Infallible`[src]

#### `fn cmp(&self, _other: &Self) -> Ordering`[src]

This method returns an `Ordering` between `self` and `other`. Read more

#### `
#[must_use]
fn max(self, other: Self) -> Self where
Self: Sized,` 1.21.0[src]

Compares and returns the maximum of two values. Read more

#### `
#[must_use]
fn min(self, other: Self) -> Self where
Self: Sized,` 1.21.0[src]

Compares and returns the minimum of two values. Read more

#### `
#[must_use]
fn clamp(self, min: Self, max: Self) -> Self where
Self: Sized,` 1.50.0[src]

Restrict a value to a certain interval. Read more

### `impl PartialEq<Infallible> for Infallible`[src]

#### `fn eq(&self, _: &Infallible) -> bool`[src]

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

#### `
#[must_use]
fn ne(&self, other: &Rhs) -> bool` 1.0.0[src]

This method tests for `!=`.

### `impl PartialOrd<Infallible> for Infallible`[src]

#### `fn partial_cmp(&self, _other: &Self) -> Option<Ordering>`[src]

This method returns an ordering between `self` and `other` values if one exists. Read more

#### `
#[must_use]
fn lt(&self, other: &Rhs) -> bool` 1.0.0[src]

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more

#### `
#[must_use]
fn le(&self, other: &Rhs) -> bool` 1.0.0[src]

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more

#### `
#[must_use]
fn gt(&self, other: &Rhs) -> bool` 1.0.0[src]

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more

#### `
#[must_use]
fn ge(&self, other: &Rhs) -> bool` 1.0.0[src]

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more

### `impl Copy for Infallible`[src]

### `impl Eq for Infallible`[src]

## Auto Trait Implementations

### `impl Send for Infallible`

### `impl Sync for Infallible`

### `impl Unpin for Infallible`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&Self) -> TypeId`[src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&Self) -> &T`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut Self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<T> From<!> for T`[src]

#### `pub fn from(!) -> T`[src]

Performs the conversion.

### `impl<T> From<T> for T`[src]

#### `pub fn from(T) -> T`[src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(Self) -> U`[src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(U) -> Result<T, <T as TryFrom<U>>::Error>`[src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

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

The type returned in the event of a conversion error.

#### `pub fn try_into(Self) -> Result<U, <U as TryFrom<T>>::Error>`[src]

Performs the conversion.