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Split core::panic module to subdirectory
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@dtolnay
dtolnay committed Jul 30, 2021
1 parent f3f8e75 commit d7c82ba
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337 changes: 8 additions & 329 deletions library/core/src/panic.rs
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#![stable(feature = "core_panic_info", since = "1.41.0")]

mod location;
mod panic_info;

use crate::any::Any;
use crate::fmt;

#[stable(feature = "panic_hooks", since = "1.10.0")]
pub use self::location::Location;
#[stable(feature = "panic_hooks", since = "1.10.0")]
pub use self::panic_info::PanicInfo;

#[doc(hidden)]
#[unstable(feature = "edition_panic", issue = "none", reason = "use panic!() instead")]
Expand Down Expand Up @@ -39,334 +46,6 @@ pub macro panic_2021 {
),
}

/// A struct providing information about a panic.
///
/// `PanicInfo` structure is passed to a panic hook set by the [`set_hook`]
/// function.
///
/// [`set_hook`]: ../../std/panic/fn.set_hook.html
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// panic::set_hook(Box::new(|panic_info| {
/// if let Some(s) = panic_info.payload().downcast_ref::<&str>() {
/// println!("panic occurred: {:?}", s);
/// } else {
/// println!("panic occurred");
/// }
/// }));
///
/// panic!("Normal panic");
/// ```
#[lang = "panic_info"]
#[stable(feature = "panic_hooks", since = "1.10.0")]
#[derive(Debug)]
pub struct PanicInfo<'a> {
payload: &'a (dyn Any + Send),
message: Option<&'a fmt::Arguments<'a>>,
location: &'a Location<'a>,
}

impl<'a> PanicInfo<'a> {
#[unstable(
feature = "panic_internals",
reason = "internal details of the implementation of the `panic!` and related macros",
issue = "none"
)]
#[doc(hidden)]
#[inline]
pub fn internal_constructor(
message: Option<&'a fmt::Arguments<'a>>,
location: &'a Location<'a>,
) -> Self {
struct NoPayload;
PanicInfo { location, message, payload: &NoPayload }
}

#[unstable(
feature = "panic_internals",
reason = "internal details of the implementation of the `panic!` and related macros",
issue = "none"
)]
#[doc(hidden)]
#[inline]
pub fn set_payload(&mut self, info: &'a (dyn Any + Send)) {
self.payload = info;
}

/// Returns the payload associated with the panic.
///
/// This will commonly, but not always, be a `&'static str` or [`String`].
///
/// [`String`]: ../../std/string/struct.String.html
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// panic::set_hook(Box::new(|panic_info| {
/// if let Some(s) = panic_info.payload().downcast_ref::<&str>() {
/// println!("panic occurred: {:?}", s);
/// } else {
/// println!("panic occurred");
/// }
/// }));
///
/// panic!("Normal panic");
/// ```
#[stable(feature = "panic_hooks", since = "1.10.0")]
pub fn payload(&self) -> &(dyn Any + Send) {
self.payload
}

/// If the `panic!` macro from the `core` crate (not from `std`)
/// was used with a formatting string and some additional arguments,
/// returns that message ready to be used for example with [`fmt::write`]
#[unstable(feature = "panic_info_message", issue = "66745")]
pub fn message(&self) -> Option<&fmt::Arguments<'_>> {
self.message
}

/// Returns information about the location from which the panic originated,
/// if available.
///
/// This method will currently always return [`Some`], but this may change
/// in future versions.
///
/// # Examples
///
/// ```should_panic
/// 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");
/// ```
#[stable(feature = "panic_hooks", since = "1.10.0")]
pub fn location(&self) -> Option<&Location<'_>> {
// NOTE: If this is changed to sometimes return None,
// deal with that case in std::panicking::default_hook and std::panicking::begin_panic_fmt.
Some(&self.location)
}
}

#[stable(feature = "panic_hook_display", since = "1.26.0")]
impl fmt::Display for PanicInfo<'_> {
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
formatter.write_str("panicked at ")?;
if let Some(message) = self.message {
write!(formatter, "'{}', ", message)?
} else if let Some(payload) = self.payload.downcast_ref::<&'static str>() {
write!(formatter, "'{}', ", payload)?
}
// NOTE: we cannot use downcast_ref::<String>() here
// since String is not available in libcore!
// The payload is a String when `std::panic!` is called with multiple arguments,
// but in that case the message is also available.

self.location.fmt(formatter)
}
}

/// A struct containing information about the location of a panic.
///
/// This structure is created by [`PanicInfo::location()`].
///
/// # Examples
///
/// ```should_panic
/// 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.
#[lang = "panic_location"]
#[derive(Copy, Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
#[stable(feature = "panic_hooks", since = "1.10.0")]
pub struct Location<'a> {
file: &'a str,
line: u32,
col: u32,
}

impl<'a> Location<'a> {
/// 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;
///
/// /// Returns the [`Location`] at which it is called.
/// #[track_caller]
/// fn get_caller_location() -> &'static Location<'static> {
/// Location::caller()
/// }
///
/// /// Returns a [`Location`] from within this function's definition.
/// fn get_just_one_location() -> &'static Location<'static> {
/// get_caller_location()
/// }
///
/// let fixed_location = get_just_one_location();
/// assert_eq!(fixed_location.file(), file!());
/// assert_eq!(fixed_location.line(), 14);
/// assert_eq!(fixed_location.column(), 5);
///
/// // running the same untracked function in a different location gives us the same result
/// let second_fixed_location = get_just_one_location();
/// assert_eq!(fixed_location.file(), second_fixed_location.file());
/// assert_eq!(fixed_location.line(), second_fixed_location.line());
/// assert_eq!(fixed_location.column(), second_fixed_location.column());
///
/// let this_location = get_caller_location();
/// assert_eq!(this_location.file(), file!());
/// assert_eq!(this_location.line(), 28);
/// assert_eq!(this_location.column(), 21);
///
/// // running the tracked function in a different location produces a different value
/// let another_location = get_caller_location();
/// assert_eq!(this_location.file(), another_location.file());
/// assert_ne!(this_location.line(), another_location.line());
/// assert_ne!(this_location.column(), another_location.column());
/// ```
#[stable(feature = "track_caller", since = "1.46.0")]
#[rustc_const_unstable(feature = "const_caller_location", issue = "76156")]
#[track_caller]
pub const fn caller() -> &'static Location<'static> {
crate::intrinsics::caller_location()
}
}

impl<'a> Location<'a> {
#![unstable(
feature = "panic_internals",
reason = "internal details of the implementation of the `panic!` and related macros",
issue = "none"
)]
#[doc(hidden)]
pub const fn internal_constructor(file: &'a str, line: u32, col: u32) -> Self {
Location { file, line, col }
}

/// 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
///
/// ```should_panic
/// 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");
/// ```
#[stable(feature = "panic_hooks", since = "1.10.0")]
pub fn file(&self) -> &str {
self.file
}

/// Returns the line number from which the panic originated.
///
/// # Examples
///
/// ```should_panic
/// 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");
/// ```
#[stable(feature = "panic_hooks", since = "1.10.0")]
pub fn line(&self) -> u32 {
self.line
}

/// Returns the column from which the panic originated.
///
/// # Examples
///
/// ```should_panic
/// 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");
/// ```
#[stable(feature = "panic_col", since = "1.25.0")]
pub fn column(&self) -> u32 {
self.col
}
}

#[stable(feature = "panic_hook_display", since = "1.26.0")]
impl fmt::Display for Location<'_> {
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(formatter, "{}:{}:{}", self.file, self.line, self.col)
}
}

/// An internal trait used by libstd to pass data from libstd to `panic_unwind`
/// and other panic runtimes. Not intended to be stabilized any time soon, do
/// not use.
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