2014-05-01 12:47:18 -05:00
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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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2014-10-09 14:17:22 -05:00
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//! Panic support for libcore
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//!
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//! The core library cannot define panicking, but it does *declare* panicking. This
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//! means that the functions inside of libcore are allowed to panic, but to be
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//! useful an upstream crate must define panicking for libcore to use. The current
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//! interface for panicking is:
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//!
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2014-06-18 03:04:35 -05:00
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//! ```ignore
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//! fn panic_impl(fmt: fmt::Arguments, &(&'static str, u32)) -> !;
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//! ```
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//!
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//! This definition allows for panicking with any general message, but it does not
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//! allow for failing with a `Box<Any>` value. The reason for this is that libcore
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//! is not allowed to allocate.
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//!
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//! This module contains a few other panicking functions, but these are just the
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//! necessary lang items for the compiler. All panics are funneled through this
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//! one function. Currently, the actual symbol is declared in the standard
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//! library, but the location of this may change over time.
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2014-05-01 12:47:18 -05:00
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2014-10-30 11:13:02 -05:00
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#![allow(dead_code, missing_docs)]
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#![unstable(feature = "core_panic",
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reason = "internal details of the implementation of the `panic!` \
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and related macros",
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issue = "0")]
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2014-05-10 15:46:05 -05:00
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use fmt;
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2014-05-26 12:33:18 -05:00
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2014-12-27 15:57:43 -06:00
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#[cold] #[inline(never)] // this is the slow path, always
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#[lang = "panic"]
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pub fn panic(expr_file_line: &(&'static str, &'static str, u32)) -> ! {
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2015-03-01 19:25:23 -06:00
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// Use Arguments::new_v1 instead of format_args!("{}", expr) to potentially
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// reduce size overhead. The format_args! macro uses str's Display trait to
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// write expr, which calls Formatter::pad, which must accommodate string
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// truncation and padding (even though none is used here). Using
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// Arguments::new_v1 may allow the compiler to omit Formatter::pad from the
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// output binary, saving up to a few kilobytes.
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let (expr, file, line) = *expr_file_line;
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panic_fmt(fmt::Arguments::new_v1(&[expr], &[]), &(file, line))
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}
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#[cold] #[inline(never)]
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#[lang = "panic_bounds_check"]
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fn panic_bounds_check(file_line: &(&'static str, u32),
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index: usize, len: usize) -> ! {
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panic_fmt(format_args!("index out of bounds: the len is {} but the index is {}",
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len, index), file_line)
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}
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#[cold] #[inline(never)]
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pub fn panic_fmt(fmt: fmt::Arguments, file_line: &(&'static str, u32)) -> ! {
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#[allow(improper_ctypes)]
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extern {
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#[lang = "panic_fmt"]
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#[unwind]
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fn panic_impl(fmt: fmt::Arguments, file: &'static str, line: u32) -> !;
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}
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let (file, line) = *file_line;
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unsafe { panic_impl(fmt, file, line) }
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}
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