Re: AC_ARG_ENABLE and checking for unrecognized switches

[Tom Tromey]

>> I use AC_ARG_ENABLE to create a number of different --enable switches.
>> I noticed when I accidentally mistyped the <something> in --enable-
>> <something>, ./configure didn't bail on the unrecognized switch.

Eric> This is by design; the GNU Coding Standards wants projects to be
Eric> aggregatable, such that someone else could write a larger project that
Eric> uses yours as a subdirectory, and takes additional --enable switches
Eric> that some (but not all) of its subprojects understand.  Being able to
Eric> blindly pass down all of its switches to subprojects, without having to
Eric> worry about which projects care about which switches, makes this easier.

I think there are a few wrinkles:

https://www.gnu.org/software/autoconf/manual/autoconf-2.68/html_node/Option-Checking.html

My reading is that there *is* checking by default, but it is turned off
if you have a subdir configure, but then can be turned back on again by
the user.

Doing something better here would be nice (though maybe difficult) since
in my experience I often forget the exact spelling... like, is it
"--disable-multilib" or "--disable-multilibs"?  Or is it "--with-python"
or "--enable-python"?

Tom