[Development] Proposing CMake as build tool for Qt 6

Alexandru Croitor alexandru.croitor at qt.io
Thu Jun 6 17:31:22 CEST 2019

On 6. Jun 2019, at 16:48, Christian Gagneraud <chgans at gmail.com<mailto:chgans at gmail.com>> wrote:

On Fri, 7 Jun 2019 at 02:25, Simon Hausmann <Simon.Hausmann at qt.io<mailto:Simon.Hausmann at qt.io>> wrote:

Am 06.06.19 um 16:17 schrieb Christian Gagneraud:
On Fri, 7 Jun 2019 at 02:08, Simon Hausmann <Simon.Hausmann at qt.io<mailto:Simon.Hausmann at qt.io>> wrote:

Am 06.06.19 um 15:52 schrieb Christian Gagneraud:
On Fri, 7 Jun 2019 at 01:35, Bogdan Vatra via Development
<development at qt-project.org<mailto:development at qt-project.org>> wrote:

I won't hold my breath for community support for iOS. iOS is out for so many
years, yet CMake has no support for t.

iOs is not a show stopper if and only you're prepared to drop this plaform
from Qt 6 in case cmake support will be poor or non existing.
IOs, Android (and other upcoming OS [1]) multi-arch  builds are IMHO a
Since when the build system "candidate" dictates Qt supported platform?
I thought it was supposed to be the other way around.

And now people are calling for "community" help b/c they realise that
it will take a massive effort to support these requirements.

FWIW, I didn't say that without support from the community nothing will
happen, which is what you're suggesting. Eventually somebody from the Qt
Company is likely going to dig into the particular topic of iOS, for
example. If you would like to see something implemented before that
point in time, then please join the development effort. We also hang out
in #qt-cmake on Freenode, btw.
That's exactly my point, "you" took the decision before analysing the
problems, and now you're asking me to join #qt-cmake to make it
happen!?! Why would i do that? Can't you provide something that works?
If not, please bail out.

As you can see from the responses, an analysis on CMake and iOS has been
done, with encouraging results. These results, on conjunction with the

No, an analisys wasn't done *prior*, an analysis of the problems is
*currently* being done.
That's my feeling right now.
None of these was mentioned in your original email.

If you read my previously sent email, I mention that the investigation was done around 2 months ago, and not *currently*.
Yes, Simon's initial email did not contain information regarding iOS, but mine did.
Simon did not have all the details, because it was not him that looked into it.

results in the other platforms/configurations, gave us - some TqTC and
KDAB devs - enough confidence that we think that we can pull it off. I

So you're basically saying  that you have no real metrics, just gut
feeling that it is possibly doable.
Please bring facts, not gut feelings.

What metrics do you expect?
With the time I had available, I discovered some issues regarding iOS + CMake, but nothing insurmountable.
I gave my analysis. We (people working on the CMake port) feel it's possible to do.
Now it's just a matter of getting to do it. But we still have other things to do first.

did not ask you to join to make it happen, please don't put words into
my mouth. I said that if you'd like to see something implemented before
we get to it, then you're invited to join the effort.

Stop saying that i put words in your mouth, i'm just reading and
interpreting what you're saying.
And right now, i've been heavily invited to something that i don't
want to join. Period.

Please stop making promises based on potential future "community
contribution" that you cannot guarantee.
We need facts, not promises and futures.

Can you multi-arch-build a Qt example/tutorial for Ios/Android right now?

Correct me if I'm wrong, but qmake does not support multi-arch builds for Android either. We provide separate packages for separate architecture.  So both CMake and qmake are the same in this regard.

We can not currently build fat libraries containing simulator + device architectures with CMake in one compiler invocation, like it is done with qmake. That needs to be fixed in CMake first. This does not mean it is impossible. And it does not mean that it will not be done.

Fat libraries with multiple arches for only simulator (x86 + x64), or only devices (arm 32 + arm64) works.

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