[Interest] [OS X/MacPorts] parallel qt4 and qt5 installs

[René J.V. Bertin]

On Friday November 14 2014 09:14:47 Thiago Macieira wrote:

Hi and thanks,

> In framework builds of OS X, Qt 4 and Qt 5 are not co-installable, since they 
> claim the same names like QtCore.framework. We decided early on in the Qt 5.0 
... 
> Therefore, you need to install them in separate prefixes.

Yes, Apple's support for multiple versions in a single framework is limited to backward compatibility; the linker will always pick the newest version.
Python allows you to get around that by providing for an optional suffix in the build system, so translated back to Qt you could have QtCore4.framework and QtCore5.framework (containing a QtCore4 and QtCore5 binary, respectively).
That's for the theory. In practice, nothing forbids us to have all of Qt4 in ${prefix}/lib/Qt4 and Qt5 in ${prefix}/lib/Qt5, right?

> qtchooser will help you. Your $PATH should contain only qtchooser, like so:
Stupid question maybe, but where does qtchooser come from? I don't see it in the Qt4 source tree ...

> But it does not help for the libraries. It will only help the executables. 
> Then qmake takes over and uses the right paths to the libraries when linking.

Ok, so making sure existing binaries don't break without a complete rebuild would require a manual set-up of all the links.
That sucks :) but not overly so :)

R.