26.0.50; CEDET stickyfunc-mode broken after recent removal of default-FOO variables

[Andrew Moore <slewsys@gmail.com>]

CEDET stickyfunc-mode appears to be broken after recent commits:

    e6681b27394a23979c3aef3925f78ef9cd75bd32 (“Nix more uses of default-FOO variables (Bug#24946)”),
    73d47d22197175f08b2dd62e76d7138872e611d2 (“Remove obsolete default-FOO variables”)

Being enamored of stickyfunc-mode, I’m hoping that someone might point me in the direction of a resolution.  What I have so far is only a partial workaround.

Prior to the above commits, CEDET and stickyfunc-mode were enabled globally via the following lines in my .emacs:

    (load (concat cedet-load-path "/semantic/loaddefs.el"))
    (semantic-mode)
    (mapc
      (lambda (mode)
        (funcall mode 1))
      '(global-semantic-idle-summary-mode
       global-semantic-idle-completions-mode
       global-semantic-idle-scheduler-mode
       global-semanticdb-minor-mode))
       global-semantic-stickyfunc-mode))

(This might be more properly done via customization, but the effect should be the same)

After commits removing the obsolete `default-FOO’ variables, including `default-header-line-format', Emacs drops into the debugger on startup as result of the above lines.  One work around is to enable stickyfunc-mode via major mode hooks.  E.g., after commenting out the last line above `global-semantic-stickyfunc-mode’, stickyfunc mode can be enabled in C mode with the following hook:

    (defun c-mode-setup ()
      "Adjust C mode environment."
      (semantic-mode)
      (make-local-variable 'header-line-format)
      (setq header-line-format
               '(:eval
                 (list
                  (propertize " " 'display
                                    '((space :align-to 0)))
                  (semantic-stickyfunc-fetch-stickyline))))
      (semantic-stickyfunc-mode))

    (add-hook 'c-mode-common-hook #'c-mode-setup)

Unfortunately, adding this to emacs-lisp-mode-hook causes Emacs to again drop into the debugger on startup.  In fact, whereas stickyfunc-mode works with C code, it seems not to have worked with Lisp for a while now (i.e., prior to removal of the `default-FOO’ variables).  Obviously it would help to identify the breaking commit, but I’m not even sure what time frame to examine.

In the mean time, perhaps someone could offer some insight into what’s going on?  Why did removal of the obsolete variable `default-header-line-format’ wreck such havoc?  Should I be looking at CEDET code, or might the problem be of a more generic nature that could be affecting other code that I haven’t come across yet?  Once enough information has been gathered, a bug report will be submitted.  Thank you!
-AM

In GNU Emacs 26.0.50.3 (x86_64-apple-darwin15.6.0, NS appkit-1404.47 Version 10.11.6 (Build 15G1108))
of 2016-11-16 built on vesta.slewsys.org
Repository revision: dc4b8a0c329a9d9e56e6be63cb4a0f59a952b07f
Windowing system distributor 'Apple', version 10.3.1404
Recent messages:
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Compilation exited abnormally with code 2

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