| //! Panic support for libcore |
| //! |
| //! The core library cannot define panicking, but it does *declare* panicking. This |
| //! means that the functions inside of libcore are allowed to panic, but to be |
| //! useful an upstream crate must define panicking for libcore to use. The current |
| //! interface for panicking is: |
| //! |
| //! ``` |
| //! # use std::fmt; |
| //! fn panic_impl(fmt: fmt::Arguments, file_line_col: &(&'static str, u32, u32)) -> ! |
| //! # { loop {} } |
| //! ``` |
| //! |
| //! This definition allows for panicking with any general message, but it does not |
| //! allow for failing with a `Box<Any>` value. The reason for this is that libcore |
| //! 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. Currently, the actual symbol is declared in the standard |
| //! library, but the location of this may change over time. |
| |
| #![allow(dead_code, missing_docs)] |
| #![unstable(feature = "core_panic", |
| reason = "internal details of the implementation of the `panic!` \ |
| and related macros", |
| issue = "0")] |
| |
| use crate::fmt; |
| use crate::panic::{Location, PanicInfo}; |
| |
| #[cold] |
| // never inline unless panic_immediate_abort to avoid code |
| // bloat at the call sites as much as possible |
| #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))] |
| #[lang = "panic"] |
| pub fn panic(expr_file_line_col: &(&'static str, &'static str, u32, u32)) -> ! { |
| if cfg!(feature = "panic_immediate_abort") { |
| unsafe { super::intrinsics::abort() } |
| } |
| |
| // Use Arguments::new_v1 instead of format_args!("{}", expr) to potentially |
| // reduce size overhead. The format_args! macro uses str's Display trait to |
| // write expr, which calls Formatter::pad, which must accommodate string |
| // truncation and padding (even though none is used here). Using |
| // Arguments::new_v1 may allow the compiler to omit Formatter::pad from the |
| // output binary, saving up to a few kilobytes. |
| let (expr, file, line, col) = *expr_file_line_col; |
| panic_fmt(fmt::Arguments::new_v1(&[expr], &[]), &(file, line, col)) |
| } |
| |
| #[cold] |
| #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))] |
| #[lang = "panic_bounds_check"] |
| fn panic_bounds_check(file_line_col: &(&'static str, u32, u32), |
| index: usize, len: usize) -> ! { |
| if cfg!(feature = "panic_immediate_abort") { |
| unsafe { super::intrinsics::abort() } |
| } |
| |
| panic_fmt(format_args!("index out of bounds: the len is {} but the index is {}", |
| len, index), file_line_col) |
| } |
| |
| #[cold] |
| #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))] |
| #[cfg_attr( feature="panic_immediate_abort" ,inline)] |
| pub fn panic_fmt(fmt: fmt::Arguments<'_>, file_line_col: &(&'static str, u32, u32)) -> ! { |
| if cfg!(feature = "panic_immediate_abort") { |
| unsafe { super::intrinsics::abort() } |
| } |
| |
| // NOTE This function never crosses the FFI boundary; it's a Rust-to-Rust call |
| #[allow(improper_ctypes)] // PanicInfo contains a trait object which is not FFI safe |
| extern "Rust" { |
| #[lang = "panic_impl"] |
| fn panic_impl(pi: &PanicInfo<'_>) -> !; |
| } |
| |
| let (file, line, col) = *file_line_col; |
| let pi = PanicInfo::internal_constructor( |
| Some(&fmt), |
| Location::internal_constructor(file, line, col), |
| ); |
| unsafe { panic_impl(&pi) } |
| } |