Many people build KDE projects and their dependencies have reported a build failure of qgpgme-qt6. Linking the tests fails:
/bin/sh ../../../libtool --tag=CXX --mode=link g++ -std=c++17 -g -O2 -Wall -Wextra -Wno-shadow -no-install -o t-addexistingsubkey t-addexistingsubkey.o t-support.o ../../cpp/src/libgpgmepp.la ../src/libqgpgmeqt6.la ../../../src/libgpgme.la -lQt6Core -lgpg-error -lQt6Test -lQt6Core -Wl,--disable-new-dtags -lstdc++ mv -f .deps/t-revokekey.Tpo .deps/t-revokekey.Po mv -f .deps/run-receivekeysjob.Tpo .deps/run-receivekeysjob.Po /bin/sh ../../../libtool --tag=CXX --mode=link g++ -std=c++17 -g -O2 -Wall -Wextra -Wno-shadow -no-install -o t-decryptverify t-decryptverify.o t-support.o ../../cpp/src/libgpgmepp.la ../src/libqgpgmeqt6.la ../../../src/libgpgme.la -lQt6Core -lgpg-error -lQt6Test -lQt6Core -Wl,--disable-new-dtags -lstdc++ /bin/sh ../../../libtool --tag=CXX --mode=link g++ -std=c++17 -g -O2 -Wall -Wextra -Wno-shadow -no-install -o t-keylist t-keylist.o t-support.o ../../cpp/src/libgpgmepp.la ../src/libqgpgmeqt6.la ../../../src/libgpgme.la -lQt6Core -lgpg-error -lQt6Test -lQt6Core -Wl,--disable-new-dtags -lstdc++ libtool: link: g++ -std=c++17 -g -O2 -Wall -Wextra -Wno-shadow -o t-keylist t-keylist.o t-support.o -Wl,--disable-new-dtags ../../cpp/src/.libs/libgpgmepp.so ../src/.libs/libqgpgmeqt6.so ../../../src/.libs/libgpgme.so -lgpg-error -lQt6Test -lQt6Core -lstdc++ -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/lang/cpp/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/lang/qt/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/usr/lib libtool: link: g++ -std=c++17 -g -O2 -Wall -Wextra -Wno-shadow -o t-addexistingsubkey t-addexistingsubkey.o t-support.o -Wl,--disable-new-dtags ../../cpp/src/.libs/libgpgmepp.so ../src/.libs/libqgpgmeqt6.so ../../../src/.libs/libgpgme.so -lgpg-error -lQt6Test -lQt6Core -lstdc++ -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/lang/cpp/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/lang/qt/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/usr/lib libtool: link: g++ -std=c++17 -g -O2 -Wall -Wextra -Wno-shadow -o t-decryptverify t-decryptverify.o t-support.o -Wl,--disable-new-dtags ../../cpp/src/.libs/libgpgmepp.so ../src/.libs/libqgpgmeqt6.so ../../../src/.libs/libgpgme.so -lgpg-error -lQt6Test -lQt6Core -lstdc++ -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/lang/cpp/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/lang/qt/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/usr/lib mv -f .deps/run-importjob.Tpo .deps/run-importjob.Po /bin/sh ../../../libtool --tag=CXX --mode=link g++ -std=c++17 -g -O2 -Wall -Wextra -Wno-shadow -no-install -o t-keylocate t-keylocate.o t-support.o ../../cpp/src/libgpgmepp.la ../src/libqgpgmeqt6.la ../../../src/libgpgme.la -lQt6Core -lgpg-error -lQt6Test -lQt6Core -Wl,--disable-new-dtags -lstdc++ libtool: link: g++ -std=c++17 -g -O2 -Wall -Wextra -Wno-shadow -o t-keylocate t-keylocate.o t-support.o -Wl,--disable-new-dtags ../../cpp/src/.libs/libgpgmepp.so ../src/.libs/libqgpgmeqt6.so ../../../src/.libs/libgpgme.so -lgpg-error -lQt6Test -lQt6Core -lstdc++ -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/lang/cpp/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/lang/qt/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/build/gpgme/src/.libs -Wl,-rpath -Wl,/home/shreevathsa/kde/usr/lib /usr/bin/ld: t-keylocate.o: copy relocation against non-copyable protected symbol `_ZTV14QTestEventLoop@@Qt_6' in /usr/lib/gcc/x86_64-pc-linux-gnu/13.1.1/../../../../lib/libQt6Test.so collect2: error: ld returned 1 exit status /usr/bin/ld: t-support.o: copy relocation against non-copyable protected symbol `_ZTV14QTestEventLoop@@Qt_6' in /usr/lib/gcc/x86_64-pc-linux-gnu/13.1.1/../../../../lib/libQt6Test.so collect2: error: ld returned 1 exit status make[4]: *** [Makefile:951: t-keylocate] Error 1 make[4]: *** Waiting for unfinished jobs.... make[4]: *** [Makefile:935: t-decryptverify] Error 1 /usr/bin/ld: t-addexistingsubkey.o: copy relocation against non-copyable protected symbol `_ZTV14QTestEventLoop@@Qt_6' in /usr/lib/gcc/x86_64-pc-linux-gnu/13.1.1/../../../../lib/libQt6Test.so /usr/bin/ld: t-keylist.o: copy relocation against non-copyable protected symbol `_ZTV14QTestEventLoop@@Qt_6' in /usr/lib/gcc/x86_64-pc-linux-gnu/13.1.1/../../../../lib/libQt6Test.so collect2: error: ld returned 1 exit status make[4]: *** [Makefile:923: t-addexistingsubkey] Error 1 collect2: error: ld returned 1 exit status make[4]: *** [Makefile:947: t-keylist] Error 1 mv -f .deps/run-refreshkeysjob.Tpo .deps/run-refreshkeysjob.Po mv -f .deps/run-signarchivejob.Tpo .deps/run-signarchivejob.Po make[4]: Leaving directory '/home/shreevathsa/kde/build/gpgme/lang/qt/tests'
This has been reported by people using Arch Linux.