[PATCH] Workaround -Wmaybe-uninitialized false positives during profiledbootstrap

[Richard Biener]

On Thu, Jan 15, 2015 at 12:29 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Thu, Jan 15, 2015 at 12:17:44PM +0100, Richard Biener wrote:
>> On Thu, Jan 15, 2015 at 12:10 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>> > Hi!
>> >
>> > I ran into -Werror=maybe-uninitialized errors during profiledbootstrap
>> > (../configure --enable-languages=c,c++ --enable-checking=release;
>> > make -j16 profiledboostrap) before I hit a miscompilation I'm going to file.
>> >
>> > Is this ok for trunk, or do we want to work around them differently?
>>
>> I wonder if we can arrange profiledbootstrap to use --disable-werror
>> unless --enable-werror is specified explicitely...  Similarly useful
>> if we could do a similar thing from non-standard build-configs...
>
> For non-standard ones I'm ok, but I've always hoped that profiledbootstrap
> is considered standard.  It certainly worked fine with -Werror at least
> for us in gcc 4.[4-9].

Indeed it did (with release checking at least).

>> I also wonder if we shouldn't simply fix the uninit pass ...
>
> If it is possible, sure, but it isn't always the case.
>
> We could also just use type var = var; if that is the way to avoid
> the warnings and not generate extra code.

Is that portable though?  (legal C, not subject to other compilers
that it might be "hineous"...)

Anyway, I guess the patch is ok if you add a comment after the inits
/* initialize to avoid warnings with profiledbootstrap */
or similar.  Otherwise people might be tempted to remove the
init again (or wonder why it is there) as it works in regular bootstrap.

Thanks,
Richard.


>         Jakub