diff options
| -rw-r--r-- | library/core/src/panicking.rs | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/library/core/src/panicking.rs b/library/core/src/panicking.rs index 683894a5ab4..aa11ae28dcb 100644 --- a/library/core/src/panicking.rs +++ b/library/core/src/panicking.rs @@ -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. |