Add PanicMessage type for PanicInfo::message(). · model-checking/verify-rust-std@ca458ba (original) (raw)
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use crate::fmt;
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use crate::fmt::{self, Display};
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`use crate::panic::Location;
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`/// A struct providing information about a panic.
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`@@ -18,6 +18,17 @@ pub struct PanicInfo<'a> {
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`force_no_backtrace: bool,
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`}
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/// A message that was given to the panic!() macro.
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///
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/// The [Display] implementation of this type will format the message with the arguments
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/// that were given to the panic!() macro.
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///
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/// See [PanicInfo::message].
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#[unstable(feature = "panic_info_message", issue = "66745")]
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pub struct PanicMessage<'a> {
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message: fmt::Arguments<'a>,
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}
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`impl<'a> PanicInfo<'a> {
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`#[inline]
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`pub(crate) fn new(
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`@@ -29,12 +40,26 @@ impl<'a> PanicInfo<'a> {
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`PanicInfo { location, message, can_unwind, force_no_backtrace }
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`}
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/// The message that was given to the panic! macro,
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/// ready to be formatted with e.g. [fmt::write].
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/// The message that was given to the panic! macro.
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///
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/// # Example
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///
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/// The type returned by this method implements Display, so it can
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/// be passed directly to [write!()] and similar macros.
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///
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/// [write!()]: core::write
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///
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/// ```ignore (no_std)
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/// #[panic_handler]
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/// fn panic_handler(panic_info: &PanicInfo<'_>) -> ! {
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/// write!(DEBUG_OUTPUT, "panicked: {}", panic_info.message());
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/// loop {}
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/// }
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/// ```
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`#[must_use]
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`#[unstable(feature = "panic_info_message", issue = "66745")]
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``
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pub fn message(&self) -> fmt::Arguments<'_> {
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self.message
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pub fn message(&self) -> PanicMessage<'_> {
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PanicMessage { message: self.message }
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`}
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`/// Returns information about the location from which the panic originated,
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`@@ -116,7 +141,7 @@ impl<'a> PanicInfo<'a> {
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`}
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`#[stable(feature = "panic_hook_display", since = "1.26.0")]
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impl fmt::Display for PanicInfo<'_> {
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impl Display for PanicInfo<'_> {
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`fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
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` formatter.write_str("panicked at ")?;
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`self.location.fmt(formatter)?;
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`@@ -125,3 +150,41 @@ impl fmt::Display for PanicInfo<'_> {
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`Ok(())
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`}
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`}
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impl<'a> PanicMessage<'a> {
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/// Get the formatted message, if it has no arguments to be formatted at runtime.
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///
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/// This can be used to avoid allocations in some cases.
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///
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/// # Guarantees
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///
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/// For panic!("just a literal"), this function is guaranteed to
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/// return Some("just a literal").
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///
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/// For most cases with placeholders, this function will return None.
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///
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/// See [fmt::Arguments::as_str] for details.
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#[unstable(feature = "panic_info_message", issue = "66745")]
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#[rustc_const_unstable(feature = "const_arguments_as_str", issue = "103900")]
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#[must_use]
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#[inline]
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pub const fn as_str(&self) -> Option<&'static str> {
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self.message.as_str()
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}
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}
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#[unstable(feature = "panic_info_message", issue = "66745")]
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impl Display for PanicMessage<'_> {
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#[inline]
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fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
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formatter.write_fmt(self.message)
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}
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}
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#[unstable(feature = "panic_info_message", issue = "66745")]
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impl fmt::Debug for PanicMessage<'_> {
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#[inline]
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fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
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formatter.write_fmt(self.message)
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}
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}
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