Location in std::panic - Rust
Description: A struct containing information about the location of a panic.

## Location

# Struct Location

1.10.0 · Source

    pub struct Location<'a> { /* private fields */ }

Expand description

A struct containing information about the location of a panic.

This structure is created by `PanicHookInfo::location()` and `PanicInfo::location()`.

## §Examples

ⓘ

    use std::panic;

    panic::set_hook(Box::new(|panic_info| {
        if let Some(location) = panic_info.location() {
            println!("panic occurred in file '{}' at line {}", location.file(), location.line());
        } else {
            println!("panic occurred but can't get location information...");
        }
    }));

    panic!("Normal panic");

## §Comparisons

Comparisons for equality and ordering are made in file, line, then column priority. Files are compared as strings, not `Path`, which could be unexpected. See `Location::file`’s documentation for more discussion.

## Implementations§

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### impl<'a> Location<'a>

1.46.0 (const: 1.79.0) · Source

#### pub const fn caller() -> &'static Location<'static>

Returns the source location of the caller of this function. If that function’s caller is annotated then its call location will be returned, and so on up the stack to the first call within a non-tracked function body.

##### §Examples

    use std::panic::Location;

    /// ```
    ///      |1        |11       |21       |31       |41
    ///    +-|---------|---------|---------|---------|--------
    /// 15 | #[track_caller]
    /// 16 | fn new_location() -> &'static Location<'static> {
    /// 17 |     Location::caller()
    ///    |     ------------------| the value of this expression depends on the caller,
    ///    |                       | since the function is marked #[track_caller]
    /// 18 | }
    /// ```
    #[track_caller]
    fn new_location() -> &'static Location<'static> {
        Location::caller()
    }

    /// ```
    ///      |1  |5    |11       |21       |31       |41       |51
    ///    +-|---|-----|---------|---------|---------|---------|---
    /// 29 | fn constant_location() -> &'static Location<'static> {
    /// 30 |     new_location()
    ///    |     ^ any invocation of constant_location() points here,
    ///    |       no matter the location it is called from
    /// 31 | }
    /// ```
    fn constant_location() -> &'static Location<'static> {
        new_location()
    }

    fn main() {
        //      |1  |5    |11       |21       |31       |41       |51
        //    +-|---|-----|---------|---------|---------|---------|---
        // 29 | fn constant_location() -> &'static Location<'static> {
        // 30 |     new_location()
        //    |     ^ `let constant` points here
        // 31 | }
        let constant = constant_location();
        assert_eq!(constant.file(), file!());
        assert_eq!((constant.line(), constant.column()), (30, 5));

        let constant_2 = constant_location();
        assert_eq!(
            (constant.file(), constant.line(), constant.column()),
            (constant_2.file(), constant_2.line(), constant_2.column())
        );

        //      |1        |11  |16  |21       |31
        //    +-|---------|----|----|---------|------
        // 55 |     let here = new_location();
        //    |                ^ `let here` points here, as `new_location()` is the callsite
        // 56 |     assert_eq!(here.file(), file!());
        let here = new_location();
        assert_eq!(here.file(), file!());
        assert_eq!((here.line(), here.column()), (55, 16));

        //      |1        |11       |21       ||32      |41       |51
        //    +-|---------|---------|---------||--------|---------|------
        // 64 |     let yet_another_location = new_location();
        //    |                                ^ `let yet_another_location` points here
        // 65 |     assert_eq!(here.file(), yet_another_location.file());
        let yet_another_location = new_location();
        assert_eq!(here.file(), yet_another_location.file());
        assert_ne!(
            (here.line(), here.column()),
            (yet_another_location.line(), yet_another_location.column())
        );
    }

1.10.0 (const: 1.79.0) · Source

#### pub const fn file(&self) -> &'a str

Returns the name of the source file from which the panic originated.

##### §`&str`, not `&Path`

The returned name refers to a source path on the compiling system, but it isn’t valid to represent this directly as a `&Path`. The compiled code may run on a different system with a different `Path` implementation than the system providing the contents and this library does not currently have a different “host path” type.

The most surprising behavior occurs when “the same” file is reachable via multiple paths in the module system (usually using the `#[path = "..."]` attribute or similar), which can cause what appears to be identical code to return differing values from this function.

##### §Cross-compilation

This value is not suitable for passing to `Path::new` or similar constructors when the host platform and target platform differ.

##### §Examples

ⓘ

    use std::panic;

    panic::set_hook(Box::new(|panic_info| {
        if let Some(location) = panic_info.location() {
            println!("panic occurred in file '{}'", location.file());
        } else {
            println!("panic occurred but can't get location information...");
        }
    }));

    panic!("Normal panic");

1.92.0 (const: 1.92.0) · Source

#### pub const fn file_as_c_str(&self) -> &'a CStr

Returns the name of the source file as a nul-terminated `CStr`.

This is useful for interop with APIs that expect C/C++ `__FILE__` or `std::source_location::file_name`, both of which return a nul-terminated `const char*`.

1.10.0 (const: 1.79.0) · Source

#### pub const fn line(&self) -> u32

Returns the line number from which the panic originated.

##### §Examples

ⓘ

    use std::panic;

    panic::set_hook(Box::new(|panic_info| {
        if let Some(location) = panic_info.location() {
            println!("panic occurred at line {}", location.line());
        } else {
            println!("panic occurred but can't get location information...");
        }
    }));

    panic!("Normal panic");

1.25.0 (const: 1.79.0) · Source

#### pub const fn column(&self) -> u32

Returns the column from which the panic originated.

##### §Examples

ⓘ

    use std::panic;

    panic::set_hook(Box::new(|panic_info| {
        if let Some(location) = panic_info.location() {
            println!("panic occurred at column {}", location.column());
        } else {
            println!("panic occurred but can't get location information...");
        }
    }));

    panic!("Normal panic");

## Trait Implementations§

1.10.0 · Source§

### impl<'a> Clone for Location<'a>

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#### fn clone(&self) -> Location<'a>

Returns a duplicate of the value. Read more
1.0.0 · Source§

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

Performs copy-assignment from `source`. Read more
1.10.0 · Source§

### impl Debug for Location<'_>

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

Formats the value using the given formatter. Read more
1.26.0 · Source§

### impl Display for Location<'_>

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

Formats the value using the given formatter. Read more
1.10.0 · Source§

### impl Hash for Location<'_>

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

Feeds this value into the given `Hasher`. Read more
1.3.0 · Source§

#### 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
1.10.0 · Source§

### impl Ord for Location<'_>

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#### fn cmp(&self, other: &Location<'_>) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more
1.21.0 · Source§

#### fn max(self, other: Self) -> Self
where Self: Sized,

Compares and returns the maximum of two values. Read more
1.21.0 · Source§

#### fn min(self, other: Self) -> Self
where Self: Sized,

Compares and returns the minimum of two values. Read more
1.50.0 · Source§

#### fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized,

Restrict a value to a certain interval. Read more
1.10.0 · Source§

### impl PartialEq for Location<'_>

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#### fn eq(&self, other: &Location<'_>) -> bool

Tests for `self` and `other` values to be equal, and is used by `==`.
1.0.0 · Source§

#### fn ne(&self, other: &Rhs) -> bool

Tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
1.10.0 · Source§

### impl PartialOrd for Location<'_>

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#### fn partial_cmp(&self, other: &Location<'_>) -> Option<Ordering>

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

#### fn lt(&self, other: &Rhs) -> bool

Tests less than (for `self` and `other`) and is used by the `<` operator. Read more
1.0.0 · Source§

#### fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
1.0.0 · Source§

#### fn gt(&self, other: &Rhs) -> bool

Tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
1.0.0 · Source§

#### fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more
1.10.0 · Source§

### impl<'a> Copy for Location<'a>

1.10.0 · Source§

### impl Eq for Location<'_>

1.10.0 · Source§

### impl Send for Location<'_>

1.10.0 · Source§

### impl Sync for Location<'_>

## Auto Trait Implementations§

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### impl<'a> Freeze for Location<'a>

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### impl<'a> RefUnwindSafe for Location<'a>

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### impl<'a> Unpin for Location<'a>

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### impl<'a> UnwindSafe for Location<'a>

## Blanket Implementations§

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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: Clone,

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#### unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (`clone_to_uninit` #126799)
Performs copy-assignment from `self` to `dest`. 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 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> 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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#### 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.