[webkit-dev] Common build system (was Re: WebKit Wishes)

[Jochen Eisinger]

On Thu, Jan 31, 2013 at 1:15 AM, Maciej Stachowiak <mjs at apple.com> wrote:

>
> On Jan 30, 2013, at 3:24 PM, Dirk Pranke <dpranke at chromium.org> wrote:
>
> > On Wed, Jan 30, 2013 at 1:50 PM, Filip Pizlo <fpizlo at apple.com> wrote:
> >> Thanks for sharing this.
> >>
> >> On Jan 30, 2013, at 1:28 PM, Eric Seidel <eric at webkit.org> wrote:
> >>
> >> I wish we only had one build system (it were easy to add/remove/move
> files).
> >>
> >> I believe changes like http://trac.webkit.org/changeset/74849 are an
> >> unhealthy sign for the project.  Adam is not the only person who has
> chosen
> >> to empty files instead of removing them.  The pain of updating 8 build
> >> system is so great, we jump through hoops to avoid it.  Which means it
> took
> >> us months to move JavaScriptCore/wtf to WTF, and will take us years to
> kill
> >> WebCore/platform.
> >>
> >>
> >> +1
> >>
> >> This is a hard problem.  It is a problem worth solving.
> >>
> >> Do you have more thoughts on this, particularly since you know quite
> well
> >> how both Xcode and gyp work?
> >>
> >> I suspect this is one of those things that it would be hard to achieve
> >> consensus on since there are so many stakeholders.  But it may be
> fruitful
> >> to have a "what if" discussion about what this might look like.
> >>
> >
> > I think we can solve this problem if we agree that we want to. I think
> > we haven't in the past mostly because we couldn't reach a consensus
> > that it was worth solving enough to really try.
> >
> > I would love to see this fixed and would be glad to work on it. I
> > think we should at least pursue this far enough to fully understand
> > what our options are and what the costs and tradeoffs might be; does
> > anyone disagree, and is anyone else willing to help pitch in?
> >
> > I think there are several possible ways we could solve this. One would
> > be to switch to a common meta-build system. My understanding is that
> > Apple's internal production build processes impose certain constraints
> > here that I don't fully understand, but I know we've discussed the
> > possibility of checking in generated project files as a workaround.
> > Maybe there are other options as well to those constraints? I would
> > love to discuss this further w/ someone from Apple ...
>
> It's far simplest for us if:
> (a) There is an Xcode project (or a Makefile) that builds the Mac port
> checked in to source control.
> (b) The generated project invokes only tools that are part of the default
> Mac OS X install.
>

Another desirable property would be to move to a more automatic way of
handling exported symbols: Currently each port that depends on this feature
has its own .exp file or similar. I think if we could move to something
that would allow for changing WebCore API without having to touch all those
files, e.g. by consistently using WEBCORE_EXPORT macros would be a big win

best
-jochen


>
> It may not be completely impossible to violate these requirements but it
> will require a lot of bureaucracy.
>
> > (Also, just to get this out of the way, I don't think gyp needs to be
> > the solution).
> >
> > Another alternative would be to write a script that did support at
> > least the common use cases (add/move/delete files). There have been
> > attempts in the past, but they have foundered on at least some
> > perceived skepticism over how well this would work w/ XCode. That
> > said, I don't think we've really pushed this to see. At some point
> > this script might turn into a meta-meta-build system, which might be
> > silly but also be the shortest path to the finish line.
> >
> > I suggest if there is interest in this we can start a new thread to
> > discuss further ...
>
> My preference would be to use a common meta-build system with a
> comfortably human-readable and human-editable syntax, and checked in
> generated project files for those ports that need them.
>
> I think a key to making this work is to get Chromium and the Apple Mac
> port onto a common build system, which will probably require both Google
> and Apple ponying up at least one person to work on this project for a
> reasonable period of time.
>
> I think the plausible meta-build-systems to use would be CMake and Gyp,
> but in both cases it may be necessary to modify them to work well for
> everyone.
>
> I'd also like to add that I think a key related issue to common build
> system is common feature configuration. The many different ways ports
> control their feature flags is super confusing. I've long wanted to
> implement common configuration management, but have not had time.
>
> Cheers,
> Maciej
>
>
>
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