# Struct proc_macro::Span

1.29.0 · source ·

    pub struct Span(/* private fields */);

Expand description

A region of source code, along with macro expansion information.

## Implementations§

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### impl Span

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#### pub fn def_site() -> Span

🔬This is a nightly-only experimental API. (`proc_macro_def_site` #54724)

A span that resolves at the macro definition site.

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#### pub fn call_site() -> Span

The span of the invocation of the current procedural macro. Identifiers created with this span will be resolved as if they were written directly at the macro call location (call-site hygiene) and other code at the macro call site will be able to refer to them as well.

1.45.0 · source

#### pub fn mixed_site() -> Span

A span that represents `macro_rules` hygiene, and sometimes resolves at the macro definition site (local variables, labels, `$crate`) and sometimes at the macro call site (everything else). The span location is taken from the call-site.

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#### pub fn source_file(&self) -> SourceFile

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

The original source file into which this span points.

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#### pub fn parent(&self) -> Option<Span>

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

The `Span` for the tokens in the previous macro expansion from which `self` was generated from, if any.

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#### pub fn source(&self) -> Span

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

The span for the origin source code that `self` was generated from. If this `Span` wasn’t generated from other macro expansions then the return value is the same as `*self`.

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#### pub fn byte_range(&self) -> Range<usize>

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

Returns the span’s byte position range in the source file.

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#### pub fn start(&self) -> Span

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

Creates an empty span pointing to directly before this span.

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#### pub fn end(&self) -> Span

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

Creates an empty span pointing to directly after this span.

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#### pub fn line(&self) -> usize

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

The one-indexed line of the source file where the span starts.

To obtain the line of the span’s end, use `span.end().line()`.

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#### pub fn column(&self) -> usize

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

The one-indexed column of the source file where the span starts.

To obtain the column of the span’s end, use `span.end().column()`.

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#### pub fn join(&self, other: Span) -> Option<Span>

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

Creates a new span encompassing `self` and `other`.

Returns `None` if `self` and `other` are from different files.

1.45.0 · source

#### pub fn resolved_at(&self, other: Span) -> Span

Creates a new span with the same line/column information as `self` but that resolves symbols as though it were at `other`.

1.45.0 · source

#### pub fn located_at(&self, other: Span) -> Span

Creates a new span with the same name resolution behavior as `self` but with the line/column information of `other`.

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

🔬This is a nightly-only experimental API. (`proc_macro_span` #54725)

Compares two spans to see if they’re equal.

1.66.0 · source

#### pub fn source_text(&self) -> Option<String>

Returns the source text behind a span. This preserves the original source code, including spaces and comments. It only returns a result if the span corresponds to real source code.

Note: The observable result of a macro should only rely on the tokens and not on this source text. The result of this function is a best effort to be used for diagnostics only.

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#### pub fn error<T: Into<String>>(self, message: T) -> Diagnostic

🔬This is a nightly-only experimental API. (`proc_macro_diagnostic` #54140)

Creates a new `Diagnostic` with the given `message` at the span `self`.

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#### pub fn warning<T: Into<String>>(self, message: T) -> Diagnostic

🔬This is a nightly-only experimental API. (`proc_macro_diagnostic` #54140)

Creates a new `Diagnostic` with the given `message` at the span `self`.

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#### pub fn note<T: Into<String>>(self, message: T) -> Diagnostic

🔬This is a nightly-only experimental API. (`proc_macro_diagnostic` #54140)

Creates a new `Diagnostic` with the given `message` at the span `self`.

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#### pub fn help<T: Into<String>>(self, message: T) -> Diagnostic

🔬This is a nightly-only experimental API. (`proc_macro_diagnostic` #54140)

Creates a new `Diagnostic` with the given `message` at the span `self`.

## Trait Implementations§

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### impl Clone for Span

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

Returns a copy of the value. Read more
1.0.0 · source§

#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl Debug for Span

Prints a span in a form convenient for debugging.

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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 MultiSpan for Span

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#### fn into_spans(self) -> Vec<Span>

🔬This is a nightly-only experimental API. (`proc_macro_diagnostic` #54140)
Converts `self` into a `Vec<Span>`.
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### impl Copy for Span

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### impl !Send for Span

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### impl !Sync for Span

## Auto Trait Implementations§

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### impl RefUnwindSafe for Span

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### impl Unpin for Span

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### impl UnwindSafe for Span

## 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<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> 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, 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.