Hi Jeff,

On Sat, May 30, 2026 at 08:29:03AM +0200, Miklos Vajna [off-list ref] wrote:

Could you please comment on this, if this tweaked rule and its
implementation in the patch looks OK to you? Let me know if I should
just wait some more.

Just to come back to this, the idea was to make the --follow behavior
slightly more useful by not always assuming we should follow a first
parent in merge commits, but see if only one parent has effective
changes to the followed file, and if so, follow that one.

I did this by doing a diff on the followed path in each parent, then
mark the parent as "interesting" if DIFF_FILE_VALID() says so. This is
true if the file is touched or the rename happens inside the merge
commit (vs that parent), but it's not true if the file is really not
touched or the file only shows up as an addition. And if we have only
have one interesting parent, then switch to this, even if it's not the
first parent. With this rule, I think we address your worry case about
"making some other cases" worse and this still works for the subtree
case, and this is relatively easy to do.

What do you think?

Thanks,

Miklos