Your bug report

#40714: Reinitialising the major mode disables which-function-mode.

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 40714@debbugs.gnu.org.

-- 
40714: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=40714
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