Re: [RFC PATCH] remote: add --fetch option to git remote set-url

[Junio C Hamano <gitster@pobox.com>]

Denton Liu <liu.denton@gmail.com> writes:

> This adds the --fetch option to `git remote set-url` such that when
> executed we move the remote.*.url to remote.*.pushurl and set
> remote.*.url to the given url argument.
>

I suspect this is a horrible idea from end-user's point of view.
"set-url --push" is used to SET pushURL instead of setting URL and
does not MOVE anything.  Why should the end user expect and remember
"set-url --fetch" works very differently?  

If there is a need for a "--move-URL-to-pushURL-and-set-pushURL"
short-hand to avoid having to use two commands

	git remote set-url --push $(git remote --get-url origin) origin
	git remote set-url $there origin

it should not be called "--fetch", which has a strong connotation of
being an opposite of existing "--push", but something else.  And
then we need to ask ourselves if we also need such a short-hand to
"--move-pushURL-to-URL-and-set-URL" operation.  The answer to the
last question would help us decide if (1) this combined operation is
a good idea to begin with and (2) what is the good name for such an
operation.

Assuming that the short-hand operation is a good idea in the first
place, without deciding what the externally visible good name for it
is, let's read on.

> +	/*
> +	 * If add_mode, we will be appending to remote.*.url so we shouldn't move the urls over.
> +	 * If pushurls exist, we don't need to move the urls over to pushurl.
> +	 */
> +	move_fetch_to_push = fetch_mode && !add_mode && !remote->pushurl_nr;

Should this kind of "the user asked for --fetch, but sometimes it is
not appropriate to honor that request" be done silently like this?

Earlier you had a check like this:

> +	if (push_mode && fetch_mode)
> +		die(_("--push --fetch doesn't make sense"));

If a request to "--fetch" is ignored when "--add" is given, for
example, shouldn't the combination also be diagnosed as "not making
sense, we'd ignore your wish to use the --fetch option"?  Similarly
for the case where there already is pushurl defined for the remote.

This is a different tangent on the same line, but it could be that
the user wants to have two (or more) pushURLs because the user wants
to push to two remotes at the same time with "git push this-remote",
so silently ignoring "--force" may not be the right thing in the
first place.  We may instead need to make the value of URL to an
extra pushURL entry (if we had one, we now have two).