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arithmetic_overflow is missed after x >>= n when overflow checks are on #164191
Description
I tried this code:
pub fn f() -> u8 {
let mut c: u8 = 10;
c >>= 1;
0xff + c
}rustc --crate-type=lib a.rs # compiles
rustc --crate-type=lib -O a.rs # errorI expected to see this happen: the same result in both builds. 0xff + c overflows (c is 5), so the deny-by-default arithmetic_overflow lint should reject it either way.
Instead, this happened: the debug build compiles, and the -O build fails:
error: this arithmetic operation will overflow
--> a.rs:4:5
|
4 | 0xff + c
| ^^^^^^^^ attempt to compute `u8::MAX + 5_u8`, which would overflow
|
= note: `#[deny(arithmetic_overflow)]` on by default
Meta
rustc --version --verbose:
rustc 1.99.0 (b940084d7 2026-09-28)
binary: rustc
commit-hash: b940084d7eb6a299eb4bfeb8e34901bc051e7ac4
commit-date: 2026-09-28
host: x86_64-unknown-linux-gnu
release: 1.99.0
LLVM version: 23.1.1
Backtrace
<backtrace>
Activity
yashaggarwal85d commentedon Oct 26, 2026
yashaggarwal85d commentedon Oct 26, 2026