1 //! Panic support for libcore
3 //! The core library cannot define panicking, but it does *declare* panicking. This
4 //! means that the functions inside of libcore are allowed to panic, but to be
5 //! useful an upstream crate must define panicking for libcore to use. The current
6 //! interface for panicking is:
10 //! fn panic_impl(fmt: fmt::Arguments, file_line_col: &(&'static str, u32, u32)) -> !
14 //! This definition allows for panicking with any general message, but it does not
15 //! allow for failing with a `Box<Any>` value. The reason for this is that libcore
16 //! is not allowed to allocate.
18 //! This module contains a few other panicking functions, but these are just the
19 //! necessary lang items for the compiler. All panics are funneled through this
20 //! one function. Currently, the actual symbol is declared in the standard
21 //! library, but the location of this may change over time.
23 // ignore-tidy-undocumented-unsafe
25 #![allow(dead_code, missing_docs)]
26 #![unstable(feature = "core_panic",
27 reason = "internal details of the implementation of the `panic!` \
32 use crate::panic::{Location, PanicInfo};
36 // never inline unless panic_immediate_abort to avoid code
37 // bloat at the call sites as much as possible
38 #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
40 pub fn panic(expr_file_line_col: &(&'static str, &'static str, u32, u32)) -> ! {
41 if cfg!(feature = "panic_immediate_abort") {
42 unsafe { super::intrinsics::abort() }
45 // Use Arguments::new_v1 instead of format_args!("{}", expr) to potentially
46 // reduce size overhead. The format_args! macro uses str's Display trait to
47 // write expr, which calls Formatter::pad, which must accommodate string
48 // truncation and padding (even though none is used here). Using
49 // Arguments::new_v1 may allow the compiler to omit Formatter::pad from the
50 // output binary, saving up to a few kilobytes.
51 let (expr, file, line, col) = *expr_file_line_col;
52 panic_fmt(fmt::Arguments::new_v1(&[expr], &[]), &(file, line, col))
55 #[cfg(not(bootstrap))]
57 // never inline unless panic_immediate_abort to avoid code
58 // bloat at the call sites as much as possible
59 #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
61 pub fn panic(expr: &str, location: &Location<'_>) -> ! {
62 if cfg!(feature = "panic_immediate_abort") {
63 unsafe { super::intrinsics::abort() }
66 // Use Arguments::new_v1 instead of format_args!("{}", expr) to potentially
67 // reduce size overhead. The format_args! macro uses str's Display trait to
68 // write expr, which calls Formatter::pad, which must accommodate string
69 // truncation and padding (even though none is used here). Using
70 // Arguments::new_v1 may allow the compiler to omit Formatter::pad from the
71 // output binary, saving up to a few kilobytes.
72 panic_fmt(fmt::Arguments::new_v1(&[expr], &[]), location)
77 #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
78 #[lang = "panic_bounds_check"]
79 fn panic_bounds_check(file_line_col: &(&'static str, u32, u32),
80 index: usize, len: usize) -> ! {
81 if cfg!(feature = "panic_immediate_abort") {
82 unsafe { super::intrinsics::abort() }
85 panic_fmt(format_args!("index out of bounds: the len is {} but the index is {}",
86 len, index), file_line_col)
89 #[cfg(not(bootstrap))]
91 #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
92 #[lang = "panic_bounds_check"]
93 fn panic_bounds_check(location: &Location<'_>, index: usize, len: usize) -> ! {
94 if cfg!(feature = "panic_immediate_abort") {
95 unsafe { super::intrinsics::abort() }
99 format_args!("index out of bounds: the len is {} but the index is {}", len, index),
106 #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
107 #[cfg_attr( feature="panic_immediate_abort" ,inline)]
108 pub fn panic_fmt(fmt: fmt::Arguments<'_>, file_line_col: &(&'static str, u32, u32)) -> ! {
109 if cfg!(feature = "panic_immediate_abort") {
110 unsafe { super::intrinsics::abort() }
113 // NOTE This function never crosses the FFI boundary; it's a Rust-to-Rust call
115 #[lang = "panic_impl"]
116 fn panic_impl(pi: &PanicInfo<'_>) -> !;
119 let (file, line, col) = *file_line_col;
120 let location = Location::internal_constructor(file, line, col);
121 let pi = PanicInfo::internal_constructor(Some(&fmt), &location);
122 unsafe { panic_impl(&pi) }
125 #[cfg(not(bootstrap))]
127 #[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
128 #[cfg_attr( feature="panic_immediate_abort" ,inline)]
129 pub fn panic_fmt(fmt: fmt::Arguments<'_>, location: &Location<'_>) -> ! {
130 if cfg!(feature = "panic_immediate_abort") {
131 unsafe { super::intrinsics::abort() }
134 // NOTE This function never crosses the FFI boundary; it's a Rust-to-Rust call
136 #[lang = "panic_impl"]
137 fn panic_impl(pi: &PanicInfo<'_>) -> !;
140 let pi = PanicInfo::internal_constructor(Some(&fmt), location);
141 unsafe { panic_impl(&pi) }