Re: [sr #111044] autoconf should assert existence of all subsidiary tools at startup

Hi -

> Frank, do you have details of those real platforms with missing diff?
> As I wrote in <https://savannah.gnu.org/support/index.php?111044>, it's
> difficult to implement this kind of sanity check without access to an
> environment that *fails* this kind of sanity check.  I could set one up
> myself but I wouldn't know if I had picked the right things to leave out.

Not a live system I use day-to-day.  But I mean I can remove
"diffutils" from my Fedora box, and see it break.

I think the point was not so much that normal & typical developer
systems may fail.  It's that unforseen restricted machines (maybe
running in minimal fashionably-"secure" buildroots) could encounter
these problems, and then QUIETLY FAIL by misconfiguring tools.

Thus the idea was just to do lightweight & obvious sanity checking on
the environment at configure startup.  e.g.:

    diff /dev/null /dev/null || exit 1


- FChE