It's odd that this worked before with 5.14, and I can't figure out what exactly changed, but it seems that .toSet is no longer defined... [ 50%] Building CXX object CMakeFiles/kdeinit_khelpcenter.dir/navigatorappitem.cpp.o /srcbuild/khelpcenter/searchhandlers/cachereader.cpp: In member function ‘QSet<QString> CacheReader::documents() const’: /srcbuild/khelpcenter/searchhandlers/cachereader.cpp:108:25: error: ‘fromList’ is not a member of ‘QSet<QString>’ return QSet<QString>::fromList( mRanges.uniqueKeys() ); ^~~~~~~~ make[2]: *** [searchhandlers/CMakeFi
I found out that this is because of the Deprecations being enabled by cmake with the existence of the .git folder.
Should be fixed now. https://cgit.kde.org/khelpcenter.git/commit/?id=b13f7b745e6109e833e47d0744251cd4b0c365de