Re: [PATCH] format-patch: teach format.useAutoBase "whenAble" option

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

Jacob Keller <jacob.e.keller@intel.com> writes:

> From: Jacob Keller <jacob.keller@gmail.com>
>
> The format.useAutoBase configuration option exists to allow users to
> enable '--base=auto' for format-patch by default.
>
> This can sometimes lead to poor workflow, due to unexpected failures
> when attempting to format an ancient patch:
>
>     $ git format-patch -1 <an old commit>
>     fatal: base commit shouldn't be in revision list
>
> This can be very confusing, as it is not necessarily immediately obvious
> that the user requested a --base (since this was in the configuration,
> not on the command line).
>
> We do want --base=auto to fail when it cannot provide a suitable base,
> as it would be equally confusing if a formatted patch did not include
> the base information when it was requested.
>
> Teach format.useAutoBase a new mode, "whenAble". This mode will cause
> format-patch to attempt to include a base commit when it can. However,
> if no valid base commit can be found, then format-patch will continue
> formatting the patch without a base commit. --base also learns the same
> mode using the term "if-able".
>
> Add tests to cover the new mode of operation for --base.

Two minor points.

 * would users get confused choosing between if-able and whenAble to
   use for the configuration and the command line option?

 * what if there is a branch called "if-able"?  The same problem
   already exists with a refname "auto", and this makes it worse.

I do not know what the best approach to solve the latter, but the
former would be easier to solve by just picking one and sticking to
it.

Thanks.