# Struct rustc_span::symbol::Symbol

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    pub struct Symbol(SymbolIndex);

Expand description

An interned string.

Internally, a `Symbol` is implemented as an index, and all operations (including hashing, equality, and ordering) operate on that index. The use of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes, because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.

Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.

## Tuple Fields§

§`0: SymbolIndex`

## Implementations§

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### impl Symbol

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#### const fn new(n: u32) -> Self

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#### pub fn new_from_decoded(n: u32) -> Self

for use in Decoder only

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#### pub fn intern(string: &str) -> Self

Maps a string to its interned representation.

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#### pub fn as_str(&self) -> &str

Access the underlying string. This is a slowish operation because it requires locking the symbol interner.

Note that the lifetime of the return value is a lie. It’s not the same as `&self`, but actually tied to the lifetime of the underlying interner. Interners are long-lived, and there are very few of them, and this function is typically used for short-lived things, so in practice it works out ok.

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#### pub fn as_u32(self) -> u32

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#### pub fn is_empty(self) -> bool

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#### pub fn to_ident_string(self) -> String

This method is supposed to be used in error messages, so it’s expected to be identical to printing the original identifier token written in source code (`token_to_string`, `Ident::to_string`), except that symbols don’t keep the rawness flag or edition, so we have to guess the rawness using the global edition.

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### impl Symbol

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#### fn is_special(self) -> bool

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#### fn is_used_keyword_always(self) -> bool

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#### fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool

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#### fn is_unused_keyword_always(self) -> bool

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#### fn is_unused_keyword_conditional( self, edition: impl Copy + FnOnce() -> Edition, ) -> bool

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#### pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool

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#### pub fn is_path_segment_keyword(self) -> bool

A keyword or reserved identifier that can be used as a path segment.

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#### pub fn is_bool_lit(self) -> bool

Returns `true` if the symbol is `true` or `false`.

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#### pub fn can_be_raw(self) -> bool

Returns `true` if this symbol can be a raw identifier.

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#### pub fn is_preinterned(self) -> bool

Is this symbol was interned in compiler’s `symbols!` macro

## Trait Implementations§

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### impl Clone for Symbol

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

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 Symbol

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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<D: SpanDecoder> Decodable<D> for Symbol

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#### fn decode(s: &mut D) -> Symbol

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### impl Display for Symbol

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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<E: SpanEncoder> Encodable<E> for Symbol

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#### fn encode(&self, s: &mut E)

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### impl Hash for Symbol

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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<CTX> HashStable<CTX> for Symbol

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#### fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher)

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### impl Ord for Symbol

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

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

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

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

Restrict a value to a certain interval. Read more
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### impl PartialEq for Symbol

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#### fn eq(&self, other: &Symbol) -> 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 for Symbol

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#### fn partial_cmp(&self, other: &Symbol) -> 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 StableCompare for Symbol

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#### const CAN_USE_UNSTABLE_SORT: bool = true

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#### fn stable_cmp(&self, other: &Self) -> Ordering

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### impl<CTX> ToStableHashKey<CTX> for Symbol

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#### type KeyType = String

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#### fn to_stable_hash_key(&self, _: &CTX) -> String

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### impl ToString for Symbol

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

Converts the given value to a `String`. Read more
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### impl Copy for Symbol

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### impl Eq for Symbol

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### impl StructuralPartialEq for Symbol

## Auto Trait Implementations§

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### impl DynSend for Symbol

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### impl DynSync for Symbol

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### impl Freeze for Symbol

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### impl RefUnwindSafe for Symbol

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### impl Send for Symbol

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### impl Sync for Symbol

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### impl Unpin for Symbol

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### impl UnwindSafe for Symbol

## Blanket Implementations§

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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: Copy,

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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> CloneToUninit for T
where T: Clone,

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#### default 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<Q, K> Comparable<K> for Q
where 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 Q
where 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 Q
where 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 Q
where 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<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<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> ToString for T
where 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 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<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,

## 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: 4 bytes