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1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // ignore-pretty : (#23623) problems when ending with // comments
13 // error-pattern:thread 'main' panicked at 'attempt to shift right with overflow'
14 // compile-flags: -C debug-assertions
16 // This function is checking that our (type-based) automatic
17 // truncation does not sidestep the overflow checking.
19 #![warn(exceeding_bitshifts)]
22 // this signals overflow when checking is on
25 // ... but when checking is off, the fallback will truncate the
26 // input to its lower three bits (= 1). Note that this is *not*
27 // the behavior of the x86 processor for 8- and 16-bit types,
28 // but it is necessary to avoid undefined behavior from LLVM.
30 // We check that here, by ensuring the result is not zero; if
31 // overflow checking is turned off, then this assertion will pass
32 // (and the compiletest driver will report that the test did not
33 // produce the error expected above).