Re: deprecation of in-tree builds

[Markus Armbruster <armbru@redhat.com>]

Peter Maydell <peter.maydell@linaro.org> writes:

> On Mon, 30 Mar 2020 at 14:26, Markus Armbruster <armbru@redhat.com> wrote:
>>
>> Peter Maydell <peter.maydell@linaro.org> writes:
>>
>> > AIUI from Paolo, the intention is to deprecate and eventually
>> > stop supporting "in-tree" builds, so that the only option is
>> > building in a separate build directory. I thought we should
>> > probably mention that in the 5.0 changelog, so I wrote up some
>> > text:
>> >
>> > https://wiki.qemu.org/ChangeLog/5.0#Build_Information
>>
>> Overdue.  Thanks for doing this!
>>
>> > Suggestions for changes/comments etc welcome.
>>
>> Looks fine to me.
>
> Consensus in the thread seemed to lean towards having
> the 'configure/make' runes auto-create a build directory;
> if we want to do that we should probably not say anything in
> the release notes, because we'll cause people to change
> unnecessarily. Or at least have them say "We recommend
> out-of-tree builds. In future we might make the commands
> that currently do an in-tree build automatically create
> and use a build directory for you." rather than a blanket
> "we're going to drop this and you should change what you
> do now".
>
> Thoughts?

I'm wary of complicating the build system to save developers a minor
change of habits.

We will have to ask developers to change habits anyway when we switch to
Meson.  I agree with Daniel's recommendation to delay changes requiring
habit-changes until then.  However, telling people to stay clear of the
unloved and brittle in-tree build is simply good advice we should not
withhold.  When you can't make the obvious way to do things the way that
has the best chance of actually working, at least have the courtesy to
point people to the way that has the best chance of actually working.

If some developers want to avoid a change of habits badly enough, surely
one or more of them will volunteer to contribute / maintain the
complications needed for that with Meson.

Whatever it takes to get rid of in-tree-only build breakages :)