On Fri, May 31, 2013 at 2:46 PM, Richard Trieu <[email protected]> wrote:
> > > > On Fri, May 31, 2013 at 2:24 PM, Richard Smith <[email protected]>wrote: > >> On Fri, May 31, 2013 at 2:04 PM, Richard Trieu <[email protected]> wrote: >> >>> >>> @jordan_rose, I want this warning. Not sure about other people >>> >>> @gribozavr, earlier versions of this did trigger on LLVM and Clang. >>> The warning has been fine-tuned since then to avoid those false positives. >>> >>> Also, I seemed to have messed up the indentation when I wrote the >>> visitors for the first -Wloop-analysis warning and managed to copy the bad >>> indentation over to this change. I will go fix them. >> >> >> Does this find any other bugs (or false positives) in other code you've >> run it on? >> > > This has found 15-20 bugs so far, with 1-2 false positives. It is > arguable that using (x+=2) in the loop header instead of two separate > increments would be clearer for the code. > 15-20 bugs and 1-2 cases of code which is correct but unclear (and can trivially be rewritten to be correct and clear) sounds compelling to me (perhaps not for an enabled-by-default warning, but I think this meets the bar for -Wall -- we could really do with some published guidelines here). Here's the most convincing form of false-positive I can come up with: #define next_field(i) ++i #define handle_field_3(x) /*nothing to do*/ for (int i = 0; i != record.size(); next_field(i)) { handle_field_1(record[i]); next_field(i); handle_field_2(record[i]); next_field(i); handle_field_3(record[i]); } ... but even here, the code would be clearer if the for-loop increment were moved into the loop body. The patch itself looks fine, subject to prior comments.
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