Re: The 'master' branch no longer compiles.

[Stefan Monnier]

>> It's a known problem. Work around it with 'make bootstrap'. See:
>> https://lists.gnu.org/r/emacs-devel/2018-11/msg00143.html
>
> A much simpler and shorter recipe is to rename .dir-locals.el before
> building, then rename it back after the build.

FWIW, I tried to track the origin of the problem but still failed to
find it.  It looks like

    rm lisp/emacs-lisp/gv.elc; make

"fixed" it this time (the error was signaled while macroexpanding
a (setf (alist-get ...) ...) in hack-dir-local-variables which ended up
(auto)loading gv).


        Stefan