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//@ build-fail
//@ compile-flags: -C debug-assertions
// This function is checking that our automatic truncation does not
// sidestep the overflow checking.
#![deny(arithmetic_overflow)]
fn main() {
// this signals overflow when checking is on
let x = 1_i8 << 17;
//~^ ERROR: this arithmetic operation will overflow
// ... 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 has only been
// shifted by one place; 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, 2_i8);
}
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