diff options
| -rw-r--r-- | src/libcore/num/mod.rs | 15 | ||||
| -rw-r--r-- | src/test/run-pass/int-abs-overflow.rs | 21 |
2 files changed, 33 insertions, 3 deletions
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs index 011830ddb78..bd7286dfa3f 100644 --- a/src/libcore/num/mod.rs +++ b/src/libcore/num/mod.rs @@ -563,13 +563,22 @@ macro_rules! int_impl { acc } - /// Computes the absolute value of `self`. `Int::min_value()` will be - /// returned if the number is `Int::min_value()`. + /// Computes the absolute value of `self`. + /// + /// # Overflow behavior + /// + /// The absolute value of `i32::min_value()` cannot be represented as an + /// `i32`, and attempting to calculate it will cause an overflow. This + /// means that code in debug mode will trigger a panic on this case and + /// optimized code will return `i32::min_value()` without a panic. #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn abs(self) -> $T { if self.is_negative() { - self.wrapping_neg() + // Note that the #[inline] above means that the overflow + // semantics of this negation depend on the crate we're being + // inlined into. + -self } else { self } diff --git a/src/test/run-pass/int-abs-overflow.rs b/src/test/run-pass/int-abs-overflow.rs new file mode 100644 index 00000000000..3f50a7d6c02 --- /dev/null +++ b/src/test/run-pass/int-abs-overflow.rs @@ -0,0 +1,21 @@ +// Copyright 2015 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// compile-flags: -Z force-overflow-checks=on + +use std::thread; + +fn main() { + assert!(thread::spawn(|| i8::min_value().abs()).join().is_err()); + assert!(thread::spawn(|| i16::min_value().abs()).join().is_err()); + assert!(thread::spawn(|| i32::min_value().abs()).join().is_err()); + assert!(thread::spawn(|| i64::min_value().abs()).join().is_err()); + assert!(thread::spawn(|| isize::min_value().abs()).join().is_err()); +} |