In-tree versions of qt5ct (0.35, 0.36) don't seem to work with Qt 5.12. According to the upstream changelog[0], version 0.37 added Qt 5.12 support. (The newest version available from upstream seems to be 0.39.) Note that qt5ct-0.{35,36} will compile and run, but won't work as intended (at least custom colors don't show up). The =qt5ct-0.36 ebuild appears to work for 0.37 with no changes. [0] https://sourceforge.net/p/qt5ct/code/HEAD/tree/trunk/qt5ct/ChangeLog
Curious enough, qt5ct used to work with new Qt versions until I reinstalled it (or just old settings happened to remain?). Nevertheless, I can confirm that the new version fixes it.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=086e63d710fe12d0e3779666df0249475e605671 commit 086e63d710fe12d0e3779666df0249475e605671 Author: Michał Górny <mgorny@gentoo.org> AuthorDate: 2019-09-22 18:31:31 +0000 Commit: Michał Górny <mgorny@gentoo.org> CommitDate: 2019-09-22 18:37:22 +0000 x11-misc/qt5ct: Bump to 0.41 Closes: https://bugs.gentoo.org/688386 Signed-off-by: Michał Górny <mgorny@gentoo.org> x11-misc/qt5ct/Manifest | 1 + x11-misc/qt5ct/qt5ct-0.41.ebuild | 51 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 52 insertions(+)