Comment 10 for bug 1747966

This is the same bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83967

It can be worked around by changing the linking order, startup code .o file must appear earlier on the command line than .o files containing the strong symbols.

Here is a minimal self contained example
https://www.mikrocontroller.net/topic/443262#5289786
(see file KL05_demo_gcc_weak_strong_bug.tar.gz and instructions in that posting)