Re: [PATCH] format-patch: assume --cover-letter for diff in multi-patch series

Patrick Steinhardt [off-list ref] writes:

On Tue, Jun 04, 2024 at 12:49:35AM +0200, Rubén Justo wrote:

quoted

If either `--interdiff` or `--range-diff` is specified without
`--cover-letter`, we'll abort if it would result in a multi-patch series
being generated.  Because the cover-letter is needed to give the diff
text in a multi-patch series.

Considering that `format-patch` generates a multi-patch as needed, let's
adopt a similar "cover as necessary" approach when using `--interdiff`
or `--range-diff`.

What does git-format-patch(1) do right now in this situation?

In any case, this change should probably have a test or two to
demonstrate that it works as advertised.

Yes.  I think the existing tests for giving --interdiff to a single
patch series serves as the "it does not trigger when it shouldn't"
side of the test, so a positive "it does what it claims to do" test
should be sufficient.

Thanks.