On Mon, Nov 29 2021, Elijah Newren wrote: [Moving this between threads, from https://lore.kernel.org/git/CABPp-BFRE2=Owf15WzkacNfdNKbkd2n4GZh7HqDokKzeviBWRw@xxxxxxxxxxxxxx/ to the patch] > On Mon, Nov 29, 2021 at 2:25 PM Ævar Arnfjörð Bjarmason > <avarab@xxxxxxxxx> wrote: >> >> On Fri, Nov 26 2021, Nikita Bobko wrote: >> >> > Steps: >> > git rebase HEAD --exec "echo foo" >> > >> > EXPECTED: since 0 commits are going to be rebased then I expect "foo" >> > NOT to be printed >> > ACTUAL: "foo" is printed >> >> I don't think this is a bug, but explicitly desired behavior. > > My reading of the docs are such that I'd expect the same as Nikita here: > > Append "exec <cmd>" after each line creating a commit in the final > history. > ... > If --autosquash is used, "exec" lines will not be appended for the > intermediate commits, and will only appear at the end of each > squash/fixup series. > > There is no line creating a commit in the final history when you do a > git rebase -i --exec "echo foo" HEAD (there is only a noop line), so > there should be no exec line. Maybe you're right & we can just change it. Keep in mind that those docs were added by a non-native speaker (or rather, I'm assuming so based on the name / E-Mail address). See c214538416e (rebase -i: teach "--exec <cmd>", 2012-06-12). I agree that the reading you've got of it is the more obvious one. The reason I thought it wasn't a bug (some of which I dug more into afterwards): 1. I read that "commit in the final history" as referring to the range of commits to be rebased. Having only one commit or zero is perfectly OK, since... 2. ... with "exec" we don't know if the "commit in the final history" isn't affected with an argument of HEAD. I.e. yes you can also provide "HEAD~", but that's the difference between having a "pick" line or not. I don't think the sequencer cares, but maybe third party scripting via the sequence editor does? We already have an explicit facility to early abort the rebasing. See ff74126c03a (rebase -i: do not fail when there is no commit to cherry-pick, 2008-10-10) So the feature that Nikita wants is already possible via GIT_SEQUENCE_EDITOR. Now, that's a painful UI, but perhaps if this patch is implemented as a 1=1 mapping to that we'll discover some new edge case that wasn't considered? 3. This isn't just a theoretical concern. It's *interactive* rebase, e.g. a perfectly fine use for it (which I've occasionally used is): # no local commits git checkout master # opens my editor with just a "noop" line git rebase -i And then adding/copying around *new* commits in the buffer and saving it, i.e. using it as an interactive text-based cherry-pick (this is particularly nice with Emacs's magit mode). For #3 we can just say "well use HEAD~ then and ignore the one 'pick'" line. Sure, I've probably only used this once or twice. I just worry that we'll break thinsg for other users because we're narrowly focusing on --exec as a way to follow-up interactive rebase commands that we insert, and forgetting that this is a generic templating language that others are intercepting and modifying. So e.g. if you want to cherry-pick new commits and always use the same 10 "exec" lines to build and test those you can just rebase to HEAD with those --exec, then copy/paste them for each new thing you insert. You can also do that with HEAD~ and carry forward any "pick" line, but that's *different*. I.e. we're forcing whoever relies on the current semantics to change their GIT_SEQUENCE_EDITOR script from (pseudocode): if grep ^noop git-rebase-todo then for c in commits do echo "pick $c" # get the exec lines for each one, if any cat git-rebase-todo done fi To something that'll have to handle a single "pick" line. >> When you do: >> >> git rebase -x 'make test' BASE >> >> You expect to run 'make test' for all of BASE..HEAD inclusive of >> "base". E.g. for HEAD~1 we'll run 'make test' twice, and you know both >> your HEAD~ and HEAD passed tests. > > This is not true. Try `git rebase -i --exec HEAD~$N` for various > values of N>0. base is not included. Sorry, I meant "inclusive of HEAD". I.e. we'll run "make test" for HEAD, not just HEAD~. Likewise with any "exec" commands. >> So why wouldn't doing the same for HEAD make sense? > > Indeed; HEAD is weirdly inconsistent and should be brought in line > with the others. I mean why shouldn't we run "make test" on HEAD, sorry. I agree that running "make test" on "base" would make no sense. You can rebase to BASE~ if you want that. But yes, the result is the same as a rebase to HEAD~, so maybe it's fine to change it... >> That being said perhaps some users would think an option or >> configuration to skip the injection of "exec" after "noop" would make >> sense in that case. >> >> But does this really have anything per-se to do with --exec? Wouldn't >> such an option/configuration be the same as rebase in general dying if >> there's no work to do? >> >> And wouldn't such a thing be more useful than a narrow change to make >> --exec a NOOP in these cases? >> >> E.g. if I've got a "topic" that has commit "A", that's since been >> integrated into my upstream and I have a script to "make test" on my >> topics, won't simply dying (and thus indicating that the topic is >> dead/integrated) be better than noop-ing? > > Why do you suggest "dying" rather than early completion with success? If you do: git rebase -i HEAD Comment out the "noop" line, and save you'll get: error: nothing to do And an exit code of 1. Maybe we should silently return 0 there, but it seems to me like this behavior needs to be consistent with whatever "noop" is trying to accomplish in general (see ff74126c03a above). That's why I said "does this really have anything per-se to do with --exec?". I.e. we already observe this behavior without --exec, we just get a noop line, and if we had no line at all we'd error with nothing to do. If we're going to make "git rebase -i HEAD" do nothing, why would it have behavior different from a TODO list of just a "noop" line (which is not the same thing as "nothing to do"). That's partially a matter of consistency, but mostly the general paranoia that if we're going to subtly change what's *probably* an obscure feature hopefully many aren't relying on, then at least having it die instead of silently "succeed" would be better. I.e. we'll now silently ignore the "--exec" commands, but didn't before.
