use gnulib to provide the newest implementation of getopt_long()

[mywave82]

TODO list:

• rebase on "autoconf / m4 update" autoconf / m4 update #24 after it is finished and implemented
• test on a non-gnu system

[mywave82]

I think Windows is the only modern version of the commonly used operating systems that is lacking getopt_long(). We need to jump back in time to old versions of BSD probably to find the need / proper test-system.

With gnulib infrastructure in place, it is easy to add other features that might be missing in different target operating systems in the future.

[dynamite1981]

This appears to be a quite involved change (include a whole new library) to support getopt_long() on Windows?

[mywave82]

(This might be historically incorrect)

There is currently an old copy of getopt() and getopt_long() (last one is a GNU extension), from about 1998 looking at the copyright header. I'm guessing back then, getopt() had many quirks in systems and due to the GNU extension, this was available as a standalone project.

Since then the code-base has been fully merged into glibc and gnulib. It is no longer contained in a single file due to header dependencies. So if we want to get up to date with possible bugfixes, and have it working on non-gnu systems (and old systems) this can be a way to go.

I can refresh the commit to more recent version of gnulib (I left description of this is in the gnulib.txt)

Alternative options:

• Split out the first commit that fixes minor issue about config.h
• Manually update getopt() and getopt_long() with fixes and maintain that (big task)
• Remote old getopt() and getopt_long() and let configure fail if not provided by the system
• Move gnulib stuff to its own branch, not poluting the main-branch (and mention it if configure fails)

[dynamite1981]

Thanks! The reason getopt is in the source tree is to support non-GNU systems, where getopt_long is not available. I agree that the included version is outdated.

I'd recommend this option: We keep the old getopt implementation, but output a compiler warning that it is old and unmaintained. It is only linked whenever the system doesn't support getopt_long. We can also point to gnulib as a potential option for users that would like a newer getopt_long. I'm also happy to add POSIX getopt as a fallback with broader system support.

Would this work?