Re: [PATCH 0/6] [C++] Drop -fpermissive hack, enable -Werror

[Pedro Alves <palves at redhat dot com>]

On 11/20/2015 09:46 AM, Yao Qi wrote:
> Pedro Alves <palves@redhat.com> writes:
> 
>> Yeah, my plan here was to "lock" (*) ports to C++ mode one by one, as soon
>> as they build in C++ mode.  Actually, I think a negative/reverse list is even
>> better.  This allows keeping track of ports/hosts people really still care
>> about, and, gives us an easy defined stopping point (when the list is clear).
>> What would you think of this approach?
> 
> Yes, this approach is OK to me.  However, as you said, we need to
> announce this on gdb@ first.  Before we build GDB in C++ mode for some
> hosts, we need to test it.  IIRC, we didn't test GDB built in C++
> before.

On my machine (x86_64 Fedora 20), C++ mode has no regressions compared to C mode.
If C++ is flipped to on by default on (e.g.) x86_64 GNU/Linux, then the x86_64 GNU/Linux
buildbot builders will automatically start testing in C++ mode too.  If we do this,
then the Fedora builder (Fedora-x86_64-cxx-build-m64) that is specifically building
with --enable-build-with-cxx should be flipped to build with --enable-build-with-cxx=no,
to catch C mode regressions, for as long as we support C mode.

> 
> Another thing in my mind is the release schedule.  We have two months,
> but people are off around Christmas and New Year.  Do we want GDB 8.0
> built in C++ in default in some hosts, such as linux?  I am not sure.

Can't see why not.  But we can always flip back to C for the release.

> 
>>
>> I should probably move this to a separate thread, push this to a branch on
>> sourceware.org (to collect a better initial set of still-needs-conversion-work
>> hosts, with community help) and announce the intent on the gdb@ list, for
>> wider visibility/discussion.
> 
> Yes, let's do that.

OK, I'll try to find some time to do it.

>>  AC_DEFUN([GDB_AC_BUILD_WITH_CXX],
>>  [
>> +  # The "doesn't support C++ yet" hall of shame.
>> +  case $host in
>> +    *-*aix* | \
>> +    *-*go32* | \
>> +    *-*darwin* | \
>> +    *-*solaris* | \
>> +    *-*nto* | \
>> +    *-*bsd* | \
>> +    xtensa*-*-linux* | \
> 
> Why do we especially exclude xtensa*-*-linux* from building in C++ mode?

Just because that one I know for sure doesn't build in C++ mode
yet -- I have a patch from Simon in my github C++ branch that fixes
gdb/xtensa-linux-nat.c in C++ mode, which is not upstream yet.

Thanks,
Pedro Alves