Subject: Re: [PATCH] Revert 'diff-merges: let "-m" imply "-p"'

From: Jonathan Nieder <[email-masked]>
Date: Fri, 6 Aug 2021 18:55:01 -0700

Hi,

Junio C Hamano wrote:

> I am somewhat puzzled.  What does "can imagine" exactly mean and
> justify this change?  A script author may imagine "git cat-file" can
> be expected to meow, but the command actually does not meow and end
> up disappointing the author, but that wouldn't justify a rename of
> "cat-file" to something else.

Sorry for the lack of clarity.  I was describing what leads a script
author to include "-m" in a place where it has no effect.

You might be inclined to wonder why it matters _why_ a script author
would do such a thing, if the script author is wrong.  To me, it
matters because it allows us to estimate how common it is for scripts
to use "-m" in this way.

The motivating example (Rust) shows that there is at least one script
that _did_ use "-m" in this way.  Rust has mitigation, but the above
logic leads me to believe that they are not the only project that will
be affected.  And more generally, when a script author has a
reasonable reason to believe something will work, they write scripts
where it _does_ work, and then an update breaks their script, I think
it's reasonable for them not to be happy.

Jonathan