On Mon, 3 Nov 2025 19:12:43 GMT, Roger Riggs <[email protected]> wrote:
>> Hmm, obviously this is a judgement call and I'm curious what others think. >> >> My opinion is that I still think there should be a warning for shifts of -1. >> >> I mean, maybe to a _real_ hacker, then of course `foo << -1` makes perfect >> sense because it's just stating the "obvious" which is "shift the low order >> bit into the high order position and set all the other bits to zero", >> right?? :) >> >> I just don't think the average Java programmer automatically understands >> that. >> >> Yes, it's an idiom or "handy trick", but if hasn't attained the status of >> being universally recognized then it doesn't deserve a special exception. >> >> On the other hand, excluding -1 from the warning would be less disruptive >> (at least, to the real hackers out there), and that has its own merits. So I >> don't have a super strong opinion about it. > > This might be worth a corpus scan to see how common it is to shift by -1 or > other constants, either int or long. > Someone, might interpret `v << -1` as a right shift, is it more likely to > misinterpret it as using more than 5/6 bits of the shift or considering it > signed. I am working on a corpus run, will take some days probably. But I am not sure if producing a warning for code that is "correct, but advanced use" is realistic. Maybe the line needs to be draw closer to "the code is probably buggy/highly suspicious". @rgiulietti - thanks, the explanation makes sense. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/27102#discussion_r2495062625
