[Development] moc output from non-local tool build

[Thiago Macieira]

On Wednesday, 10 November 2021 03:29:15 PST Marius Kittler wrote:
> Am Dienstag, 9. November 2021, 19:59:29 CET schrieb Thiago Macieira:
> > On Friday, 5 November 2021 08:28:20 PST Scott Bloom wrote:
> > > Why wouldn’t they simply have two versions of Qt ( or more) the one they
> > > are targeting for desktop, and the previous one they are targeting for
> > > android/"remote"
> > 
> > I don't mind that. If we enforce you must have a matching version of the
> > host tools, then we do it.
> > 
> > Since I don't cross compile, people who do should speak up and explain why
> > it would be too difficult for them to have a native build of the same
> > version of Qt they're going to cross-compile.
> > 
> > Silence will mean consent.
> 
> It would of course be possible to conduct a 2nd host build which would only
> be updated in accordance with the cross-builds. I suppose it would also be
> possible to strip this 2nd build down to "tools only" by specifying some
> CMake variables. It also needed to be installed within a different prefix
> to avoid conflicts with the normal host build.

Please clarify what you meant by "2nd host build". Do mean "2nd build, which 
is host" or did you really mean "another host build for a total of 3 builds"? 
I assume it's the former.

Considering tools aren't going to be bootstrapped any more, the host build of 
the tools might be quite complete. It needs to include at least every library 
that the tools depend on. So for example it will need to go all the way to 
qttools to build QtHelp so qhelpgenerator may link to it. I don't know if 
there's something that we can do in the CMake side to enable only those 
targets by default, but the difference might actually be so small that it's 
not worth maintaining.

> However, it would certainly be more efficient and less packaging work to
> simply be able to reuse the normal host build which is already in the
> distribution. So it would just make packaging easier.

Indeed. The proposal was how old that build can be. Can you count on the host 
Linux distribution being up-to-date enough to have N-1 or even N-3? Because 
you can't, then the point is moot.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel DPG Cloud Engineering