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

[Dirk Pranke]

On Thu, Jan 31, 2013 at 11:48 AM, Hugo Parente Lima
<hugo.lima at openbossa.org> wrote:
> On Wednesday, January 30, 2013 04:15:48 PM Maciej Stachowiak 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.
>>
>> 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.
>
> I have a patch trying to solve this issue for CMake based ports[1], the patch
> still on going, but even a change affecting just 2-3 ports using the same build
> system is a bit hard to get a consensus, so you can imagine how hard will be
> to get a consensus over all WebKit ports.
>
> [1] https://bugs.webkit.org/show_bug.cgi?id=103162
>

This is slightly off-topic, but I had thought that no one was actually
using CMake; maybe I was mistaken and just none of the ports that
build on webkit.org are? It looks like Blackberry and maybe a WinCE
port uses CMake? Anyone else?

-- Dirk