Avoid optionaly depends on zip for NCZarr

[mwestphal]

No description provided.

[CLAassistant]

All committers have signed the CLA.

[WardF]

Thanks for this; we'll need to make the appropriate changes in configure.ac as well, to cover our bases for both build systems we support, but this looks good, thanks!

[mwestphal]

@WardF It looks like I need to sign a CLA, however, the CLA in the link is for an individual. Do you have a CLA for an entity that my company could sign ?

[WardF]

@dopplershift Do we have a CLA for entities?

[WardF]

@mwestphal Thanks, that's a good question, and the first time (to my knowledge) we've been asked. Stand by while I get an answer for you :)

[dopplershift]

Here's our entity CLA.

[WardF]

Thanks @dopplershift ! @mwestphal, the link to our entity CLA has been linked, and again, here.

[mwestphal]

Here is the signed CLA, waiting for your signature.
CLA-UCAR.docx.pdf

[WardF]

Thanks! Reviewing the PR's now that I've got a lingering issue taken care of and need to get caught up on PR's. @dopplershift, the signed organizational CLA was provided above. What's our next step?

[DennisHeimbigner]

It occurs to me that this change is not what I would expect.
The case I am concerned with is:

1. ENABLE_NCZARR_ZIP is on (which is the default)
2. libzip is not available.

The current code makes libzip required in this case, which I assume will cause
an error. I think that is inconsistent with our current practice.
It probably should remove the required flag and if the find_package(zip)
fails, then report a warning, but do not cause the build to fail.

[mwestphal]

This is indeed my intent. If a user require an option but the project can't provide it, an error is expected imo. But I'll let you the judge of it.

[DennisHeimbigner]

But the problem is that the naive user will see his build fail
because libzip is not installed even though he said nothing
about zip in his command line options. Remember, your code
enabled zip by default. To get the proper behavior, you have
to make zip disabled by default.

[mwestphal]

that is fair to turn it off by default imo.