On Wed, May 23, 2018 at 11:42 PM, Michael Tuexen <michael.tue...@macmic.franken.de> wrote: >> On 24. May 2018, at 08:36, Matthew Macy <mm...@freebsd.org> wrote: >> >> On Wed, May 23, 2018 at 11:35 PM, Michael Tuexen >> <michael.tue...@macmic.franken.de> wrote: >>>> On 24. May 2018, at 06:51, Matthew Macy <mm...@freebsd.org> wrote: >>>> >>>> Warnings find bugs PERIOD. Although most are not useful, I've found >>> Some warnings indicate bugs, some warnings are just wrong. If you >>> have a "may be used uninitialized" warning being a false positive, you >>> may silences the warning by just set it to zero in the declaration and >>> you silence it. Other compilers might then correctly report an >>> assignment without affect... >> >> I have yet to see a double assignment be flagged as assignment without >> effect. If it _does_ occur then we have to disable the warning on the >> compiler that we have less faith in. > Have seen it in the past in a difference project... But you miss my point: > > Not all warnings indicate bugs PERIOD. Some warning are just wrong...
Have you read my follow up? _Many_ Many warnings are wrong. Please respond to that on what the global policy should be. The value of any one particular instance of a warning does not merit discussion. -M , in this case the assignment should be added with >>>>> a comment /* pacify gcc */. >>>>> >>>>> On Wed, May 23, 2018 at 03:59:33PM -0700, Matthew Macy wrote: >>>>> M> On Wed, May 23, 2018 at 3:57 PM, Gleb Smirnoff <gleb...@freebsd.org> >>>>> wrote: >>>>> M> > The initialization isn't useful. >>>>> M> >>>>> M> It silences a gcc warning. So yes it is. It's this exchange which is >>>>> not useful. >>>>> M> >>>>> M> -M >>>>> M> >>>>> M> >>>>> M> > On Wed, May 23, 2018 at 03:52:42PM -0700, Matthew Macy wrote: >>>>> M> > M> Talk to the gcc devs. The warning is useful even if there are >>>>> false positives. >>>>> M> > M> >>>>> M> > M> On Wed, May 23, 2018 at 3:27 PM, Gleb Smirnoff >>>>> <gleb...@freebsd.org> wrote: >>>>> M> > M> > Hi, >>>>> M> > M> > >>>>> M> > M> > On Sat, May 19, 2018 at 05:10:52AM +0000, Matt Macy wrote: >>>>> M> > M> > M> Author: mmacy >>>>> M> > M> > M> Date: Sat May 19 05:10:51 2018 >>>>> M> > M> > M> New Revision: 333860 >>>>> M> > M> > M> URL: https://svnweb.freebsd.org/changeset/base/333860 >>>>> M> > M> > M> >>>>> M> > M> > M> Log: >>>>> M> > M> > M> sendfile: annotate unused value and ensure that npages is >>>>> actually initialized >>>>> M> > M> > M> >>>>> M> > M> > M> Modified: >>>>> M> > M> > M> head/sys/kern/kern_sendfile.c >>>>> M> > M> > M> >>>>> M> > M> > M> Modified: head/sys/kern/kern_sendfile.c >>>>> M> > M> > M> >>>>> ============================================================================== >>>>> M> > M> > M> --- head/sys/kern/kern_sendfile.c Sat May 19 05:09:10 >>>>> 2018 (r333859) >>>>> M> > M> > M> +++ head/sys/kern/kern_sendfile.c Sat May 19 05:10:51 >>>>> 2018 (r333860) >>>>> M> > M> > M> @@ -341,7 +341,7 @@ sendfile_swapin(vm_object_t obj, struct >>>>> sf_io *sfio, o >>>>> M> > M> > M> } >>>>> M> > M> > M> >>>>> M> > M> > M> for (int i = 0; i < npages;) { >>>>> M> > M> > M> - int j, a, count, rv; >>>>> M> > M> > M> + int j, a, count, rv __unused; >>>>> M> > M> > M> >>>>> M> > M> > M> /* Skip valid pages. */ >>>>> M> > M> > M> if (vm_page_is_valid(pa[i], vmoff(i, off) & >>>>> PAGE_MASK, >>>>> M> > M> > M> @@ -688,6 +688,7 @@ retry_space: >>>>> M> > M> > M> if (space == 0) { >>>>> M> > M> > M> sfio = NULL; >>>>> M> > M> > M> nios = 0; >>>>> M> > M> > M> + npages = 0; >>>>> M> > M> > M> goto prepend_header; >>>>> M> > M> > M> } >>>>> M> > M> > M> hdr_uio = NULL; >>>>> M> > M> > >>>>> M> > M> > This initialization is redundant and a compiler warning if >>>>> exists is wrong. >>>>> M> > M> > >>>>> M> > M> > If we jump down to prepend_header with nios == 0, we won't ever >>>>> use npages. >>>>> M> > M> > >>>>> M> > M> > -- >>>>> M> > M> > Gleb Smirnoff >>>>> M> > >>>>> M> > -- >>>>> M> > Gleb Smirnoff >>>>> >>>>> -- >>>>> Gleb Smirnoff >>>> >>> > _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
