Re: [Question]: Question about "cherry-pick" internal

From: Chris Torek <chris.torek@gmail.com>
Date: Aug 7, 2022, 16:48 UTC
Message-ID: <CAPx1Gvd9xLdJaWiTN1MrktyEMfKmAjTx9zxOVcOnRv7r9n_ZiQ@mail.gmail.com>
In-Reply-To: <e564b1e3-0f34-dce3-400d-439a40ec4d48@intel.com>

On Wed, Aug 3, 2022 at 6:42 PM Wang, Lei <lei4.wang@intel.com> wrote:

> I heard that cherry-pick is just a kind of merge, the difference between
> it and the traditional merge is that it treats the parent commit of the
> commit you want to cherry-pick as the merge-base ...

This is indeed the case.

> [During merging:] If the [two] diff[s] modified the same
> line, then a conflict occurs.

This is also true—but it's not the whole story.

> If the above is true, but why when I cherry-picked a commit, a conflict
> occurs even the 2 diffs didn't modify the same line, they modified the
> two consecutive lines (line n and line n + 1), so what can be the
> potential reason for this?

In any merge, if the two sides modify *adjacent* lines—as is the case here—that, too, is considered a conflict (at least Git considers it as one; not all merge algorithms do that).

Note that if the two diffs modify the same line(s) in the *same way*— e.g., both add the same text or delete the same text—Git will take only *one copy* of the change, without calling it a conflict. In some cases this may be incorrect: consider. e.g., merging the debits and credits in a series of accounting records, where the dollar amounts are identical, but the transactions are different. If Alice spent $5 and Bob spent $5, the correct result is not that "$5 total was spent" but rather $10.

Still, for the kinds of tasks *Git* is asked to merge, this is normally the correct result, so it is the result Git produces.

Git is a tool—or rather, a set of tools—and its automated work is never a substitute for expert evaluation. You, the user, must do some work here as well, to make sure that what Git did is in fact correct for your particular situation.

Chris