36 lines
1.4 KiB
Rust
36 lines
1.4 KiB
Rust
// 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.
|
|
|
|
// ignore-pretty : (#23623) problems when ending with // comments
|
|
|
|
// error-pattern:thread 'main' panicked at 'attempt to shift right with overflow'
|
|
// compile-flags: -C debug-assertions
|
|
|
|
// This function is checking that our (type-based) automatic
|
|
// truncation does not sidestep the overflow checking.
|
|
|
|
#![warn(exceeding_bitshifts)]
|
|
|
|
fn main() {
|
|
// this signals overflow when checking is on
|
|
let x = 2_i8 >> 17;
|
|
|
|
// ... but when checking is off, the fallback will truncate the
|
|
// input to its lower three bits (= 1). Note that this is *not*
|
|
// the behavior of the x86 processor for 8- and 16-bit types,
|
|
// but it is necessary to avoid undefined behavior from LLVM.
|
|
//
|
|
// We check that here, by ensuring the result is not zero; if
|
|
// overflow checking is turned off, then this assertion will pass
|
|
// (and the compiletest driver will report that the test did not
|
|
// produce the error expected above).
|
|
assert_eq!(x, 1_i8);
|
|
}
|