[MacPorts] #44193: qt: allow side by side installation of qt4-mac and qt5-mac

[MacPorts]

#44193: qt: allow side by side installation of qt4-mac and qt5-mac
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  Reporter:  mojca@…           |      Owner:  mcalhoun@…
      Type:  enhancement       |     Status:  new
  Priority:  Normal            |  Milestone:
 Component:  ports             |    Version:
Resolution:                    |   Keywords:
      Port:  qt4-mac, qt5-mac  |
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Comment (by rjvbertin@…):

 * It's very likely that KF5 will require a Qt5 install with specific
 patches that we may not want to impose on everyone. Ports cannot depend on
 a variant, so in that case a dedicated port will be required. I agree
 that's a much stronger argument for a dedicated port than simply the
 install layout.

 * There is no question of maintaining 2 variants of all dependents. Proper
 configuration of the PortGroup will ensure that ports that do not have a
 hard requirement on the one or the other (and thus a conflict with the
 other or the one) will build with all Qt ports. There could be 1 or 2
 corresponding variants that act as a protection against installing the
 wrong binary build, but that's handled purely in the PortGroup, and
 maintained by the qt*-kde maintainer (which I reckon would be me).

 I've been very clear I think that there is absolutely no reason to change
 more to the current install layout than strictly necessary, and good
 reasons to *not* to do that ''*)''. It seems Mojca agrees with me; maybe
 we should invite opinions from more "core" MacPorts developers who are
 maybe more likely to provide additional arguments based on MacPorts
 guidelines. ("Follow Linux/Freedesktop/XDG conventions" , "avoid
 duplicating directory structures", etc.)

 I'm compelled to come back one last time to my suggestion to commit my qt4
 -mac-devel (which wouldn't even "destroy" the existing qt4-mac-devel; that
 one was very obsolete last time I looked). Mojca voiced concerns about
 repeated and expensive rebuild cycles, and I understand that we're now
 facing pressure to "get through with it already" because of 10.11's
 imminent release.

 I cannot really imagine that there will be many early updaters who are on
 old hardware where building Qt is an issue. Providing an up-to-date qt4
 -mac-devel will give the other early updaters a working solution that may
 even be replaced by a drop-in replacement qt4-mac port in the end.

 And that wouldn't exclude applying the 10.11 patch to the current port
 (without even rev-bumping it; not required for users who do not already
 have an installed version).

 ''*) I do realise that I should have kept a record of the issues I
 identified while experimenting with an all-encompassing install prefix
 myself.''

-- 
Ticket URL: <https://trac.macports.org/ticket/44193#comment:73>
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