In particular, the File Style and local variables settings are rarely
used precision instruments, for configuring unusual files unusually.
This indicates that we should not set c-file-style in the .dir-locals.el
file of the Emacs source tree.
Actually, I wonder: why would it be correct to use another style than GNU
for C files inside the Emacs source tree?
I don't think it's a feature that dir-locals.el takes precedence over
mode-hooks (it's more of an accident that we consider sufficiently
harmless not to fix it, especially since a fix would probably be
difficult/inconvenient/buggy), but in this case it seems to provide just
the behavior we want. I mean we do want to "impose" the GNU style in
our files, no matter what the user usually prefers.
What am I missing?