zygoloid wrote:
> > But still I feel generate a warning for this case went too far.
>
> Yeah, that's probably right. Maybe for `-` on a signed operand, we should
> just return the original range with the `NonNegative` flag cleared out, and
> shouldn't add the extra bit for the `-128 -> 128` edge case. That's not
> technically correct, but probably is more useful in practice.
Hm. That change will reintroduce a false positive warning for:
```c++
bool b(signed char c) {
return -c >= 128;
}
```
... that this patch fixed. But we don't produce a false positive for `0 - c >=
128`, so I still think what we ought to do here is to make `-c` behave the same
way that `0 - c` does.
https://github.com/llvm/llvm-project/pull/126846
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