Make parameter $column_key optional in array_column()

[vudaltsov]

Quite often in my code I reindex object collections via array_column. However, I have to explicitly pass null to $column_key instead of skipping it. Here's a change that makes possible this:

- array_column($objects, null, 'name');
+ array_column($objects, index_key: 'name');

Does it require a discussion in internals or an RFC?

[TimWolla]

Looking at the documentation (https://www.php.net/manual/en/function.array-column.php), I'm seeing there is not currently an example for this use case. Would you be interested in sending a PR? That would probably be a good first step to “advertise” this feature a little more. Personally I wasn't aware that this was possible yet.

As for the change itself: I'm not sure if “reindexing” an array should be the default use case for this function. I'd rather say that the user should be forced to make an explicit choice to make accidental misuse / typos less likely. So a discussion on Internals should happen at least.

The patch itself LGTM, though.