bug#43037: Eval error in the ‘c-lang-defvar’ or ‘c-lang-setvar’

[Eli Zaretskii]

> Date: Fri, 16 Oct 2020 14:43:53 +0000
> Cc: AC <achirvasub@gmail.com>, larsi@gnus.org, 43037@debbugs.gnu.org
> From: Alan Mackenzie <acm@muc.de>
> 
> >   Eval error in the ‘c-lang-defvar’ or ‘c-lang-setvar’ for
> >   ‘font-lock-comment-end-skip’ (fallback source eval - js-mode
> >   compiled with CC Mode 5.34 but loaded with 5.34.1): (error
> >   "‘c-font-lock-comment-end-skip’ got no (prior) value in js-mode
> >   (might be a cyclic reference)")
> 
> > Alan, can you take a look, please?
> 
> Yes, I think the problem is precisely what the error message said.
> js-mode.el was compiled (quite a long time ago) when c-version was still
> 5.34, but since then c-version has become 5.34.1.  So their is a clash
> between what js-mode.el was compiled with and the CC Mode current in the
> Emacs version.
> 
> To resolve this, I think deleting lisp/progmodes/js-mode.elc and
> compiling lisp/progmodes/js-mode.el again should sort out the problem.

You are right.

> This problem has happened more than once.  I think the solution should
> be in the Makefile to add a dependency of js-mode.elc on cc-defs.el.

Yes, please.  On the emacs-27 branch, please.

Thanks.