WTB Qt 5.12LTS (port:qt512) (attn mcalhoun)

[Marcus Calhoun-Lopez]

> May I ask why Qt 5.12LTS isn't in MacPorts, for those users who prefer stability or want to develop against a stable version?

The last time we added a Qt version just because it was LTS, there were objections.
Unfortunately, I cannot find the reference, but the consensus was essentially:
if the newest version works on all the platforms that the LTS does, then there is no reason to keep another Qt port around.
I argued for keeping the LTS version, but there was little enthusiasm for it.

> And in general, suppose it did exist: how good is the support for installing port:qt51x manually and then getting the corresponding dependencies on the correct, corresponding Qt version?

If a user, for example, on macOS Mojave installs qt511-qtbase, then all ports that use the qt5 PG should correctly recognize it is a valid Qt5 port that satisfies the dependencies.
There are probably not a lot people using this configuration, so problems may still exist.
There is an issue with prebuilt binaries.
Some (most?) ports that depend on Qt will have to be (re)built from source to accommodate the different library versions.
`rev-upgrade` should catch these problems.
 
Not too long ago, there was a discussion on how to improve the situation [1], but no consensus was reached.

-Marcus

[1] https://lists.macports.org/pipermail/macports-dev/2018-May/thread.html#38834

> On Nov 17, 2019, at 6:01 AM, René J.V. Bertin <rjvbertin at gmail.com> wrote:
> 
> Hi,
> 
> May I ask why Qt 5.12LTS isn't in MacPorts, for those users who prefer stability or want to develop against a stable version?
> 
> And in general, suppose it did exist: how good is the support for installing port:qt51x manually and then getting the corresponding dependencies on the correct, corresponding Qt version?
> 
> R.