Re: Kernel build error in hwpmc with system GNU cc

On Thu, May 2, 2013 at 3:42 PM, Andrey Chernov <ache_at_freebsd.org> wrote:
> On 02.05.2013 14:06, Davide Italiano wrote:
>>> /usr/src/sys/modules/hwpmc/../../dev/hwpmc/hwpmc_core.c:1935: warning: 'map' may be used uninitialized in this function
>>> *** [hwpmc_core.o] Error code 1
>
>> You can find a patch attached at the end of this mail that should fix
>> the problem.
>
> Thanks, it fix this warning.
>
>> More generally speaking, why are you building -CURRENT using GCC while
>> the default compiler has been clang since November 2012?
>
> 1) clang is not ready for production, it is too buggy. See its fixes
> rate for very common things 'must work' in every compiler. It is
> included into -current not because of its quality, but to involve
> developers into clang bugfixes to make its progress faster, and
> personally me don't want to find clang bugs.
>
> 2) Its build time is too long.
>
> 3) It generates bigger code.
>
>> Putting the additional burden of
>> testing on the committer because two compilers are supported at the
>> same time doesn't scale really well, at least according to me.
>
> You'll hit this error later in any case, attempting to MFC your changes
> to -stable with GNU cc.
>
> --
> bitcoin:13fGiNutKNHcVSsgtGQ7bQ5kgUKgEQHn7N


I won't object about your 2) and 3), but if you fear to hit bugs you
shouldn't probably run -CURRENT.
About the backport, I faced the problem of adapting code in the past
when merging to stable releases, so this is actually a different
problem. If I'd blindly merged the incrimined change to 9-STABLE
without building and notifying the GCC warning, then I would expect
you ranting at me because of build failure.
There's a notion of "default compiler" in 9 and in 10 and they're
different. My opinion is that people should live with it, and unless
someone will introduce some mechanism a-la redports.org to overcome
the issue, I will take my risks committing changes and fixing failures
if they occur. It's already really difficult to have tinderbox not
ranting these days, adding another compiler just result in another
dimension of complexity in the whole scenario.

Thanks,

-- 
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare