On Mon, Oct 30, 2023 at 10:33 PM Junio C Hamano [off-list ref] wrote:

Junio C Hamano [off-list ref] writes:

quoted

Elijah Newren [off-list ref] writes:

quoted

I thought the point of the comment_line_char was so that commit
messages could have lines starting with '#'.  That rationale doesn't
apply to the TODO list generation or parsing, and I'm not sure if we
want to add the same complexity there.

Earlier I said

quoted

Thanks for a healthy dose of sanity.  I noticed existing use of
comment_line_char everywhere in sequencer.c and assumed we would
want to be consistent, but you are right to point out that they are
all about the COMMIT_EDITMSG kind of thing, and not about what
appears in "sequencer/todo".

but with something as simple as

    $ git -c core.commentchar='@' rebase -i master seen^2

I can see that the references to comment_line_char in sequencer.c
are about the commented lines after the list of insn in the
generated sequencer/todo file, so even though the rationale does not
apply, isn't this already "broken" in the current code anyway?

Yes, I believe it is.  However, I remember specifically looking at
cases with --rebase-merges about a year and a half ago, and noted that
there was a mixture of hardcoded '#' references along with
comment_line_char.  I noted at the time that changing
comment_line_char looked like it had a bug, and that the parsing in
particular would be fooled and do wrong things if it changed.
Unfortunately, I can't find any notes from the time with the details,
so I don't remember exactly what or how it was triggered.

However, I do suspect that the references to comment_line_char in the
`rebase -i` codepaths was not for any actual intended purpose, but
just noting that they were used elsewhere in the file (for
COMMIT_EDITMSG, where it made sense) and just mimicking that code
without realizing the lack of rationale.  That would have been mere
wasted effort had the comment_line_char been consistently supported in
the TODO file editing and parsing, but it wasn't, which left TODO
editing & parsing somewhat broken.

I think supporting comment_line_char for the TODO file provides no
value, and I think the easier fix would be undoing the uses of
comment_line_char relative to the TODO file (perhaps also leaving
in-code comments to the effect that comment_line_char just doesn't
apply to the TODO file).

However, if someone prefers to make the TODO file also respect
comment_line_char, despite its dubious value, then I expect any patch
should
  1) audit *every* reference found via git grep -e '".*#' -e "'#'" sequencer.c
  2) add a test case (or cases) involving --rebase-merges -i that
trigger the relevant code paths
If they don't do that, then I fear we might make the bug more likely
to be triggered rather than less.