# Enum cargo::core::features::Edition

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    pub enum Edition {
        Edition2015,
        Edition2018,
        Edition2021,
    }

Expand description

The edition of the compiler (RFC 2052)

The following sections will guide you how to add and stabilize an edition.

### Adding a new edition

- Add the next edition to the enum.
- Update every match expression that now fails to compile.
- Update the `FromStr` impl.
- Update `CLI_VALUES` to include the new edition.
- Set `LATEST_UNSTABLE` to Some with the new edition.
- Add an unstable feature to the `features!` macro invocation below for the new edition.
- Gate on that new feature in `TomlManifest::to_real_manifest`.
- Update the shell completion files.
- Update any failing tests (hopefully there are very few).
- Update unstable.md to add a new section for this new edition (see this example).

### Stabilization instructions

- Set `LATEST_UNSTABLE` to None.
- Set `LATEST_STABLE` to the new version.
- Update `is_stable` to `true`.
- Set the editionNNNN feature to stable in the `features!` macro invocation below.
- Update any tests that are affected.
- Update the man page for the `--edition` flag.
- Update unstable.md to move the edition section to the bottom.
- Update the documentation:
  - Update any features impacted by the edition.
  - Update manifest.md#the-edition-field.
  - Update the `--edition` flag (options-new.md).
  - Rebuild man pages.

## Variants§

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### Edition2015

The 2015 edition

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### Edition2018

The 2018 edition

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### Edition2021

The 2021 edition

## Implementations§

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### impl Edition

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#### pub const LATEST_UNSTABLE: Option<Edition> = None

The latest edition that is unstable.

This is `None` if there is no next unstable edition.

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#### pub const LATEST_STABLE: Edition = Edition::Edition2021

The latest stable edition.

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#### pub const CLI_VALUES: [&'static str; 3] = _

Possible values allowed for the `--edition` CLI flag.

This requires a static value due to the way clap works, otherwise I would have built this dynamically.

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#### pub(crate) fn first_version(&self) -> Option<Version>

Returns the first version that a particular edition was released on stable.

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#### pub fn is_stable(&self) -> bool

Returns `true` if this edition is stable in this release.

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#### pub fn previous(&self) -> Option<Edition>

Returns the previous edition from this edition.

Returns `None` for 2015.

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#### pub fn saturating_next(&self) -> Edition

Returns the next edition from this edition, returning the last edition if this is already the last one.

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#### pub(crate) fn cmd_edition_arg(&self, cmd: &mut ProcessBuilder)

Updates the given `ProcessBuilder` to include the appropriate flags for setting the edition.

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#### pub(crate) fn supports_compat_lint(&self) -> bool

Whether or not this edition supports the `rust_*_compatibility` lint.

Ideally this would not be necessary, but editions may not have any lints, and thus `rustc` doesn’t recognize it. Perhaps `rustc` could create an empty group instead?

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#### pub(crate) fn supports_idiom_lint(&self) -> bool

Whether or not this edition supports the `rust_*_idioms` lint.

Ideally this would not be necessary…

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#### pub(crate) fn default_resolve_behavior(&self) -> ResolveBehavior

## Trait Implementations§

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### impl Clone for Edition

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#### fn clone(&self) -> Edition

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 Debug for Edition

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

Formats the value using the given formatter. Read more
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### impl<'de> Deserialize<'de> for Edition

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#### fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
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### impl Display for Edition

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

Formats the value using the given formatter. Read more
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### impl FromStr for Edition

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#### type Err = Error

The associated error which can be returned from parsing.
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#### fn from_str(s: &str) -> Result<Self, Error>

Parses a string `s` to return a value of this type. Read more
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### impl Hash for Edition

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#### fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given `Hasher`. Read more
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#### fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more
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### impl Ord for Edition

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#### fn cmp(&self, other: &Edition) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more
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#### fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values. Read more
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#### fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values. Read more
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#### fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval. Read more
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### impl PartialEq<Edition> for Edition

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#### fn eq(&self, other: &Edition) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`.
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#### fn ne(&self, other: &Rhs) -> bool

This method tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl PartialOrd<Edition> for Edition

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#### fn partial_cmp(&self, other: &Edition) -> Option<Ordering>

This method returns an ordering between `self` and `other` values if one exists. Read more
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#### fn lt(&self, other: &Rhs) -> bool

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more
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#### fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
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#### fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
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#### fn ge(&self, other: &Rhs) -> bool

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

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#### fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>where __S: Serializer,

Serialize this value into the given Serde serializer. Read more
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### impl Copy for Edition

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### impl Eq for Edition

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### impl StructuralEq for Edition

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### impl StructuralPartialEq for Edition

## Auto Trait Implementations§

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### impl RefUnwindSafe for Edition

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### impl Send for Edition

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### impl Sync for Edition

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### impl Unpin for Edition

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### impl UnwindSafe for Edition

## 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,

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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 Twhere 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<Q, K> Comparable<K> for Qwhere Q: Ord + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn compare(&self, key: &K) -> Ordering

Compare self to `key` and return their ordering.
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### impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Compare self to `key` and return `true` if they are equal.
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### impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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### impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Compare self to `key` and return `true` if they are equal.
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### impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. 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, U> Into<U> for Twhere 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> Same<T> for T

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#### type Output = T

Should always be `Self`
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### impl<T> ToOwned for Twhere 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> ToString for Twhere T: Display + ?Sized,

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#### default fn to_string(&self) -> String

Converts the given value to a `String`. Read more
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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.
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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 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.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<V, T> VZip<V> for Twhere V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<T> DeserializeOwned for Twhere T: for<'de> Deserialize<'de>,

## 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:1 byte

Size for each variant:

- `Edition2015`: 0 bytes
- `Edition2018`: 0 bytes
- `Edition2021`: 0 bytes