cmake: support -DBUILD_GUI=qt6 #861

1. 
   whitslack commented at 5:36 am on March 31, 2025: contributor

   This PR adds support in CMakeLists.txt for -DBUILD_GUI=qt6 to allow building against system-installed Qt6 libraries in distributions that are dropping support for Qt5 (such as Gentoo).

   I specify Qt 6.2.4 as a minimum requirement based on the work in bitcoin/bitcoin#24798, but I do not know whether Bitcoin Core currently builds against such an old version of Qt6. I have successfully built v29.0rc2 against Qt 6.8.3.

2. cmake: support -DBUILD_GUI=qt6 f331f9d765
3. 
   DrahtBot commented at 5:36 am on March 31, 2025: contributor

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4. 
   fanquake commented at 5:37 am on March 31, 2025: member

   Thanks, however the changes to switch to Qt6 are being done in https://github.com/bitcoin/bitcoin/pull/30997.
5. fanquake closed this on Mar 31, 2025

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6. 
   fanquake commented at 5:38 am on March 31, 2025: member

   (There are no plans to support both qt 5 & 6 at the same time.
7. 
   whitslack commented at 5:54 am on March 31, 2025: contributor

   Oh balls. When I searched the issue tracker for Qt6 progress, I had is:issue in my query, so I didn’t find the new PR. :man_facepalming:

   Thanks for the pointer.

8. whitslack deleted the branch on Mar 31, 2025

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whitslack DrahtBot fanquake