Re: [PATCH v7 00/13] Finish converting git bisect to C part 2

>
> Hi Miriam,
>
> On Wed, 23 Sep 2020, Johannes Schindelin wrote:
>
> > On Wed, 23 Sep 2020, Miriam R. wrote:
> >
> > > Applying some of your suggestions related to removing some 'eval' in
> > > git-bisect shell script, a bug has appeared. It seems it is related to
> > > a previous code merged before my internship.
> >
> > Now you got me curious: what bug did you see?
>
> I found your fork and ran the test, and this is the first symptom:
>
> -- snip --
> [...]
> ++ git bisect skip
> Bisecting: 1 revision left to test after this (roughly 1 step)
> [32a594a3fdac2d57cf6d02987e30eec68511498c] Add <4: Ciao for now> into <hello>.
> ++ git bisect good
> ++ grep '3082e11d3a0f2edca194c8ce1eb802256e38e75e is the first bad commit' my_bisect_log.txt
> 3082e11d3a0f2edca194c8ce1eb802256e38e75e is the first bad commit
> ++ git bisect log
> ++ git bisect reset
> Previous HEAD position was 32a594a Add <4: Ciao for now> into <hello>.
> Switched to branch 'other'
> ok 22 - bisect skip: add line and then a new test
>
> expecting success of 6030.23 'bisect skip and bisect replay':
>         git bisect replay log_to_replay.txt > my_bisect_log.txt &&
>         grep "$HASH5 is the first bad commit" my_bisect_log.txt &&
>         git bisect reset
>
> ++ git bisect replay log_to_replay.txt
> error: update_ref failed for ref 'refs/bisect/bad': cannot update ref 'refs/bisect/bad': trying to write ref 'refs/bisect/bad' with nonexistent object 10006d020000000068986d020000000054f65f00
> error: last command exited with $?=1
> not ok 23 - bisect skip and bisect replay
> #
> #               git bisect replay log_to_replay.txt > my_bisect_log.txt &&
> #               grep "$HASH5 is the first bad commit" my_bisect_log.txt &&
> #               git bisect reset
> -- snap --
>
> So I dug a little bit further (and applied Christian's patch in the
> meantime), and it turns out that the `eval` has nothing to do with what I
> originally thought it would be required for: I thought that it wanted to
> prevent `exit` calls from actually exiting the script.
>
> Instead, those `eval` calls are required because the arguments are
> provided in quoted form. For example, during the execution of t6030.68,
> the `eval` would expand the call
>
>         eval "git bisect--helper --bisect-start $rev $tail"
>
> to
>
>         git bisect--helper --bisect-start '--term-old' 'term2' '--term-new' 'term1'
>
> Therefore, the `eval` really needs to stay in place (also the other `eval`
> I had originally suggested to remove, for the same reason).

>
> I would still recommend appending `|| exit`, even if it just so happens
> that we will eventually abort when the `bisect--helper` command failed
> anyway, because the next command will then fail, and abort. But it's
> cleaner to abort already when this invocation failed rather than relying
> on that side effect.