[llvm] r216170 - Make format_object_base's destructor protected and non-virtual.

[David Blaikie]

On Fri, Aug 22, 2014 at 11:11 AM, Owen Anderson <resistor at mac.com> wrote:
>
>> On Aug 22, 2014, at 11:02 AM, David Blaikie <dblaikie at gmail.com> wrote:
>>
>> On Fri, Aug 22, 2014 at 10:38 AM, Owen Anderson <resistor at mac.com> wrote:
>>>
>>> On Aug 21, 2014, at 2:14 PM, David Blaikie <dblaikie at gmail.com> wrote:
>>>
>>> On Thu, Aug 21, 2014 at 1:34 PM, Justin Bogner <mail at justinbogner.com>
>>> wrote:
>>>
>>> Benjamin Kramer <benny.kra at googlemail.com> writes:
>>>
>>> Author: d0k
>>> Date: Thu Aug 21 06:22:05 2014
>>> New Revision: 216170
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=216170&view=rev
>>> Log:
>>> Make format_object_base's destructor protected and non-virtual.
>>>
>>> It's not meant to be used with operator delete and this avoids
>>> emitting virtual dtors for every derived format object.
>>>
>>>
>>> This change is obviously for the better, but it triggers a warning when
>>> building with clang 3.4 (and probably every clang back to 2.9 or so),
>>> which is pretty unfortunate.
>>>
>>> The problem is, until r208449, we didn't know not to warn about this on
>>> final classes or when the destructor was protected. I'm not entirely
>>> sure what we should do here, but this is likely to break anyone who
>>> builds with -Werror for a while.
>>>
>>>
>>> Only if they don't update their compiler - I usually just roll my
>>> clang release compiler (disabling -Werror) when this sort of thing
>>> comes up.
>>>
>>> For those who want to use old/pre-installed/official release clangs
>>> rather than more recent iterations, they can just disable -Werror
>>> (it's not the default anyway).
>>>
>>>
>>> This isn’t a workable solution for some of us who are tied to specific
>>> toolchain releases and can’t upgrade on a moment’s notice.  And even if I’m
>>> not building with -Werror, this change generates hundreds or thousands of
>>> warnings across an LLVM build, which makes it practically impossible to do
>>> any development work because of my own work getting lost in the sea of
>>> noise.
>>
>> You can disable the warning - as with bad MSVC/GCC warnings, we
>> usually rely on buildbots/other developers to catch the bugs that slip
>> through from users on compilers with buggy diagnostics.
>
> Actually, you can’t.  The CMake build system forcibly enables -Wnon-virtual-dtor.

Do we have an argument ordering problem? I'd imagine the CMake
defaults should go before any custom C/CXX FLAGS the user specifies,
thus allowing the user to override them.