Deprecate mixing the url option with host, dbname and a few others

[nicolas-grekas]

As proposed in #1331

For discussion. (I'll take care of tests once the discussion has settled.)

[ostrolucky]

You mean #1331, not #1334, right?

@stof I'm not quite sure what you meant with #1331 (comment), is that still a problem in this PR?

I like this PR though, IMO it's ok to finish it.

[nicolas-grekas]

I extracted the part about override_url in #1342 because deprecating the other options requires updating a lot of tests, and also because the discussion should be split apart.

[stof]

@ostrolucky this PR does not deprecate options like server_version, only the ones corresponding to the standard parts of the URL (the query string being used by DBAL for extra options is something totally specific to DBAL, relying on DBAL option names).
So it can be fine with me.

However, we should be careful when writing the upgrade guide (asking people to dynamically create a URL in the config file from separate username, host, password and db name is quite fragile, as it would probably miss the need for URL escaping, which will only trigger a bug after some time when rotating the password to one using special URL chars for instance)

[ostrolucky]

Just a reminder that after #1331 has been merged, we expect this to be finished next.

[nicolas-grekas]

I went with a more conservative approach that should provide the same benefit:

what is now deprecated is mixing the url option with host, dbname and a few others.

[ostrolucky]

Yep that's good compromise I think

[ostrolucky]

I think driver is missing, isn't it?

[nicolas-grekas]

driver is in another branch of the config tree.
I don't think that's an issue.

[ostrolucky]

thx @nicolas-grekas