On Tue, Jan 31, 2017 at 03:33:04PM -0700, Jeff Law wrote:
> My general inclination is to ask this to wait for gcc-8 as it is not a
> regression, but instead a false positive in a new warning.
Well, as the warning is enabled by -Wall, the false positives in it are
regressions (while false negatives are not, as it is a new warning).
> However, if we see this triggering with any significant frequency, then we
> should reevaluate. Getting Marek's build logs and grepping through them
> might guide us a bit on this...
>
>
> I'm not sure what the rationale is for length of zero at level 1 and length
> of one at higher levels for unknown strings. I guess I can kindof see the
> former, though I suspect if we looked at the actual strings, zero length
> would actually be uncommon.
>
> For level 1 and above assuming a single character seems way too tolerant.
> We're issuing a "may" warning, so ISTM we ought to be assuming a much larger
> length here. I realize that makes a lot more noise for the warning, but
> doesn't that better reflect what may happen?
If the compiler doesn't know anything useful about the string lengths
(and that is the case when the value range is VARYING or just extremely
large), then using the maximum bounds is really not useful at all.
We would then have to complain about every "%s %s" because in theory that
would not fit into address space and similar.
Jakub
