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Fix compile-time integer overflow when using ! on unsigned values

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Since the values are stored in a u64 internally, we need to be mask away the
high bits after applying the ! operator. Otherwise, these bits will be set to
one, causing overflow.
This commit is contained in:
inrustwetrust 2015-05-17 10:04:15 +02:00
parent 5e535eae5c
commit d1605deab8
2 changed files with 34 additions and 3 deletions
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21
src/test/run-pass/issue-23968-const-not-overflow.rs Normal file
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// 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.
const U8_MAX_HALF: u8 = !0u8 / 2;
const U16_MAX_HALF: u16 = !0u16 / 2;
const U32_MAX_HALF: u32 = !0u32 / 2;
const U64_MAX_HALF: u64 = !0u64 / 2;
fn main() {
assert_eq!(U8_MAX_HALF, 0x7f);
assert_eq!(U16_MAX_HALF, 0x7fff);
assert_eq!(U32_MAX_HALF, 0x7fff_ffff);
assert_eq!(U64_MAX_HALF, 0x7fff_ffff_ffff_ffff);
}