array_change_key_case(): Throw ValueError on invalid argument

[Girgias]

This should be merged after 8.4 has been cut.

[cmb69]

Thank you! Looks good. Also nice to get of the contrived test cases.

[jorgsowa]

Do we need RFC for such changes? I have similar PR in #15647

[cmb69]

I don't think such changes require an RFC (maybe in theory, but barely practical). Given #16641, we may consider to be more conservative, and deprecate passing anything but CASE_UPPER and CASE_LOWER first.

[bukka]

I think we should maybe put a general RFC how to deal with this. My preference is really to go through deprecations. I don't think we need to do RFC for each case but having some agreement (e.g. or possibly a single RFC) would be good.

[bukka]

Btw. if we agree that deprecations are better for those case, I don't think we need RFC.

[Girgias]

Those should be warnings not deprecations if we are not turning them into ValueErrors.
I really struggle to understand the obsession of everything that is "wrong" needing to be a deprecation.

[cmb69]

I would turn them into ValueErrors with the next major version. So far users could pass arbitrary integers; PHP 8.5 deprecates passing anything else than CASE_UPPER and CASE_LOWER. In PHP 9.0 passing anything else will throw a ValueError.