which-function-mode: put hook function on after-change-major-mode-hook
, rather than find-file-hook. This keeps which-function-mode active should the major mode be reinitialized. Also accept a null result from add-log-current-defun as definitive, should that function have run. This fixes bug #40714. * lisp/progmodes/which-func.el (which-func-ff-hook): Put on after-change-major-mode-hook. (which-function): Enhance the logic to accept a null result from add-log-current-defun.