Re: [PATCH] rebase -x: sanity check command

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Junio,

On Mon, 28 Jan 2019, Junio C Hamano wrote:

> Phillip Wood <phillip.wood@talktalk.net> writes:
> 
> > From: Phillip Wood <phillip.wood@dunelm.org.uk>
> >
> > If the user gives an empty argument to --exec then the rebase starts to
> > run before erroring out with
> >
> >   error: missing arguments for exec
> >   error: invalid line 2: exec
> >   You can fix this with 'git rebase --edit-todo' and then run 'git rebase --continue'.
> >   Or you can abort the rebase with 'git rebase --abort'.
> 
> Hmph.  I do agree that the above makes an unfortunate end-user
> experience, but I would sort-of imagine that it would even be nicer
> for such an empty exec to behave as if it were "exec false" but with
> less severe error message, i.e. a way for the user to say "I want to
> break the sequence here and get an interactive session".  We may not
> even need to add the "break" insn if we go that way and there is one
> less thing for users to learn.  I dunno, but I tend to prefer giving
> a useful and safe behaviour to interactive users other than erroring
> out, when there _is_ such a safe behaviour that is obvious from the
> situation, and I feel that an empty "exec" is such a case.

That would make things unnecessarily confusing. An empty command is not
`false` with a gentler error message. An empty command is a missing
command.

I am, however, concerned that special-casing an empty command will not
make things better: if the user called `git rebase --exec=fasle`, they
will *still* have to clean up their edit script.

Or just `git rebase --abort`, which I would do whether I had forgotten to
specify a command or whether I had a typo in my command.

> > Also check that the command does not contain any newlines as the
> > todo-list format is unable to cope with multiline commands. Note that
> > this changes the behavior, before this change one could do
> >
> > git rebase --exec='echo one
> > exec echo two'
> 
> It is very good to check the input, regardless of what an empty
> "exec" should do.

Should we then also check for incorrect quoting, missing commands, other
errors? I am not sure that this path leads to sanity.

Ciao,
Dscho