Created attachment 199521 [details] patch to devel/qt4-assistant* These two ports need the usual gcc-based patch to allow the building of math/qtiplot on powerpc64. I do not know enough about these ports to know if qtiplot will be relevant to qt5.
Created attachment 199523 [details] revised patch to include devel/qt4-designer Three ports need to be patched to enable build of qtiplot, not just two.
A commit references this bug: Author: adridg Date: Sun Dec 9 20:11:53 UTC 2018 New revision: 487079 URL: https://svnweb.freebsd.org/changeset/ports/487079 Log: Fix some Qt4 ports to build on powerpc64. All the Qt4 stuff is EOL, but let's spread it to more platforms while it's still there. These fixes were reported in the context of building math/qtiplot. PR: 233479 Submitted by: linimon Reported by: linimon Changes: head/devel/qt4-assistant/Makefile head/devel/qt4-assistant-adp/Makefile head/devel/qt4-designer/Makefile
math/qtiplot is Qt4 only; there are newer releases but it is no longer Open Source in any meaningful way. You can only get demo snaps or pre-built customer versions.