Re: Optimizing writes to unchanged files during merges?

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Apr 12, 2018, 23:35 UTC
Message-ID: <CA+55aFxA9YVLoh_23V8Hi+X7ODEmqg-dhdAYZz1jbq5JhXqBFw@mail.gmail.com>
In-Reply-To: <xmqqtvsg10bu.fsf@gitster-ct.c.googlers.com>

On Thu, Apr 12, 2018 at 4:17 PM, Junio C Hamano <gitster@pobox.com> wrote:

Show 6 quoted lines

>
> A bit of detour.  "Change in side branch happened to be a subset of
> the change in trunk and gets subsumed, but we end up writing the
> same result" happens also with the simpler resolve strategy.
>
> Here is a fix.

Heh. Except git-merge-one-file.sh is *only* used for that case, so this doesn't fix the normal case.

I verified that the normal case situation is that "update_file_flags()" thing that checks out the end result.

It's called by this case:

        } else if (a_oid && b_oid) {
                /* Case C: Added in both (check for same permissions) and */
                /* case D: Modified in both, but differently. */
                clean_merge = merge_content(o, path,
                                            o_oid, o_mode, a_oid,
a_mode, b_oid, b_mode,
                                            NULL);

in process_entry(), and I think we could just there add a test for if o_old,o_mod == a_oid,a_mode or something?

              Linus