Module `panicking`

Panic support for core

In core, panicking is always done with a message, resulting in a core::panic::PanicInfo containing a fmt::Arguments. In std, however, panicking can be done with panic_any, which throws a Box<dyn Any> containing any type of value. Because of this, std::panic::PanicHookInfo is a different type, which contains a &dyn Any instead of a fmt::Arguments. std's panic handler will convert the fmt::Arguments to a &dyn Any containing either a &'static str or String containing the formatted message.

The core library cannot define any panic handler, but it can invoke it. This means that the functions inside of core are allowed to panic, but to be useful an upstream crate must define panicking for core to use. The current interface for panicking is:

fn panic_impl(pi: &core::panic::PanicInfo<'_>) -> !
# { loop {} }

This module contains a few other panicking functions, but these are just the necessary lang items for the compiler. All panics are funneled through this one function. The actual symbol is declared through the #[panic_handler] attribute.

Modules

panic_const

Functions

const_panic_fmt This function is used instead of panic_fmt in const eval.
panic The underlying implementation of core's panic! macro when no formatting is used.
panic_display
panic_fmt The entry point for panicking with a formatted message.
panic_nounwind Like panic, but without unwinding and track_caller to reduce the impact on codesize on the caller. If you want #[track_caller] for nicer errors, call panic_nounwind_fmt directly.
panic_nounwind_fmt Like panic_fmt, but for non-unwinding panics.
panic_nounwind_nobacktrace Like panic_nounwind, but also inhibits showing a backtrace.
panic_str_2015 This exists solely for the 2015 edition panic! macro to trigger a lint on panic!(my_str_variable);.
unreachable_display