Created attachment 527314 [details]
Output of emerge --info
dev-qt/qtcore-5.9.4-r2 is installed without issue. After that equery check dev-qt/qtcore-5.9.4-r2 shown:
!!! /usr/include/qt5/Gentoo/gentoo-qconfig.h has wrong mtime (is 1523573441, should be 1523573422)
!!! /usr/lib64/qt5/mkspecs/qconfig.pri has wrong mtime (is 1523573441, should be 1523573367)
!!! /usr/lib64/qt5/mkspecs/qmodule.pri has incorrect MD5sum
* Checking dev-qt/qtcore-5.9.4-r2 ...
1385 out of 1388 files passed
A similar result is shown with qcheck dev-qt/qtcore-5.9.4-r2.
It also happens for dev-qt/qtcore-5.7.1-r4.
The eclass qt5-build.eclass write to the live file system after checksums and timestamps are recorded in package database.
This is intentional. The alternative (and old behaviour) is that these files are not owned by any package at all.