[Development] Qt 6 co-installability with Qt 5

[Joerg Bornemann]

On 2/26/21 2:23 PM, Kai Köhne wrote:

>> With https://codereview.qt-project.org/c/qt/qtbase/+/336652 a copy is made
>> if a hard-link cannot be created.
> 
> Right, but that is at configure time, this doesn’t help with the online installer.

To be pedantic, it's at cmake --install time. :-)

> If we go down this route, we should arguably check in the online installer whether the target folder is on an NTFS partition, and back out if not. One more complication ... :/

Well my optimistic theory is:
- CI builds + installs the Qt module (for example qtbase) in a packaging 
config.
- CI creates a 7z archive and either 7za is clever and detects the hard 
link or just archives the binary twice.
- The installer extracts the archive on the user's machine. Either the 
archived hard links can be extracted or copies are made.


Cheers,

Joerg