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Update doc comment about core::panicking.

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This commit is contained in:
Mara Bos 2023-10-02 14:12:37 +02:00
parent 331b8a3edd
commit 83dd214f06
1 changed files with 9 additions and 7 deletions
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16
library/core/src/panicking.rs
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@ -1,7 +1,14 @@
//! Panic support for core
//!
//! The core library cannot define panicking, but it does *declare* panicking. This
//! means that the functions inside of core are allowed to panic, but to be
//! 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::PanicInfo 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:
//!
@ -10,11 +17,6 @@
//! # { loop {} }
//! ```
//!
//! This definition allows for panicking with any general message, but it does not
//! allow for failing with a `Box<Any>` value. (`PanicInfo` just contains a `&(dyn Any + Send)`,
//! for which we fill in a dummy value in `PanicInfo::internal_constructor`.)
//! The reason for this is that core is not allowed to allocate.
//!
//! 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.