From: Erik Cervin Edin Date: Sun, 24 May 2026 15:00:26 GMT Subject: Re: [PATCH 1/1] commit: allow -m/-F with --fixup=amend: or reword: Message-ID: In-Reply-To: > > > --fixup=amend: and --fixup=reword: require an editor to supply the > > > replacement commit message. The -m and -F flags are rejected: -m is > > > caught by a die() in prepare_to_commit(), and -F is caught by > > > die_for_incompatible_opt4() which groups -F with --fixup as mutually > > > exclusive. This makes these modes unusable in non-interactive > > > workflows -- notably AI coding agents. > > > > "Unusable" may be stronger than reality, as you can make creatie use > > of GIT_EDITOR to achieve what you want. "awkward" or "poorly suited" > > would be more fitting. > > Indeed Fair, "poorly suited" is more accurate. It's not impossible, just very awkward. > > > Plain --fixup (without amend: or reword:) continues to reject -F but > > > still accepts -m (even though it's practically a no-op). > > > > Is it "practically a no-op"? No, I was mistaken. The message is kept until autosquash. The `-m` option may be used to supplement the log message of the created commit, but the additional commentary will be thrown away once the "fixup!" commit is squashed into __ by `git rebase --autosquash`. I was trying to fill in the gaps here on the intent of the pre-existing behavior (to reject -F with --fixup) and I kind of assumed the message was being discarded. > > For the same reason, "-F" would be just as useful as "-m" in this context, > > and it feels a bit inconsistent to allow one while rejecting the other. > > Yes, looking at the way the code is structured I wonder if these options > were made incompatible to simplify the implementation, or maybe the > implementation merely reflects those restrictions. I think it would. I kept the pre-existing behavior because I wasn't sure if the rejection meant "Error. You are doing something that doesn't make sense -- you probably meant to do something else" or "Sorry. What you're trying to do is not supported" A closer look at the original implementation 30884c9afc (commit: add support for --fixup -m"", 2017-12-22) makes it clear the intent here is the latter: Those options could also support combining with -m, but given what they do I can't think of a good use-case for doing that, so I have not made the more invasive change of splitting up the logic in commit.c to first act on those, and then on -m options. There is a case to not reject them, it was just deemed unnecessary complex for something without a clear use-case. In the ideal case, given that -m works (and does something useful), it's reasonable to expect -F to do the same (for the same reasons as --fixup=reword:.) Although, it's arguably less crucial in this usecase. Given what its ephemeral nature, such a message is likely a terse comment, -m "forgot to format" or similar. I think it makes sense to allow -F for all --fixup variations, for consistency. For the plain --fixup, -c/-C are probably less justifiable, but -F mirroring -m seems worthwhile for consistency's sake in all variations. > > A potential problem of the above code is if we find something wrong > > in message and complain later in the control flow > > in message and complain later in the control flow, we have long lost > > where the message came from, as the point of the above code is > > exactly to pretend that "--fixup:amend/reword -F" message did *not* > > come from a file with the "-F" option, but from the command line via > > the "-m" option. Now that you mention this, I guess a message on stdin can be arbitrarily large, have null bytes and maybe some other oddities which the -m would never have. > I wonder how hard it would be to refactor prepare_to_commit() > so that it can accommodate "--fixup=amend: -F" I think this is doable. > > > +test_expect_success '--fixup=amend: with -m option' ' > > > commit_for_rebase_autosquash_setup && > > > - echo "fatal: options '\''-m'\'' and '\''--fixup:reword'\'' cannot be used together" >expect && > > > - test_must_fail git commit --fixup=reword:HEAD~ -m "reword commit message" 2>actual && > > > - test_cmp expect actual > > > + cat >expected <<-EOF && > > > > This comment is not about the added logic, but I notice that among > > 86 hits with string "expect" in this file in today's "master", only > > 14 hits are with string "expected", i.e., the prevalent name for the > > "golden copy result" that is compared with the actula result (called > > "actual") is "expect", not "expected". Please do not make the > > situation worse. Mea culpa. I overlooked this distinction. > In this case it would be better to use > > test_commit_message HEAD <<-EOF > amend! $(git log -1 --format=%s HEAD~) > > amend commit message > EOF > > and avoid creating actual and expect all together. That would also work (except it has to be HEAD~2, since the reword commit advances HEAD by one) Thank you both for the review. I will reroll as a V2 taking your suggestions into account. - Erik