KDevelop 5.6 isn't the most exciting IDE release in recent times but brings with it a focus on better stability, performance, and with future maintainability in mind for its code-base.
KDevelop 5.6 does bring with it the ability to display inline notes for problems at the end of the line, better CMake project support with a variety of improvements, better C++ language support, better PHP language handling, support for Python 3.9, and a variety of other improvements.
More details on the KDevelop 5.6 release and for downloads via KDevelop.org .