Re: [PATCH 2/2] t3430: update to test with custom commentChar

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

Hi Daniel,

[I forgot to address this mail earlier, my apologies]

On Tue, 10 Jul 2018, Daniel Harding wrote:

> On Tue, 10 Jul 2018 at 16:08:57 +0300, Johannes Schindelin wrote:>
> > On Tue, 10 Jul 2018, Daniel Harding wrote:
> > 
> > > On Mon, 09 Jul 2018 at 22:14:58 +0300, Johannes Schindelin wrote:
> > > >
> > > > On Mon, 9 Jul 2018, Daniel Harding wrote:
> > > > >
> > > > > On Mon, 09 Jul 2018 at 00:02:00 +0300, brian m. carlson wrote:
> > > > > >
> > > > > > Should this affect the "# Merge the topic branch" line (and the "#
> > > > > > C",
> > > > > > "# E", and "# H" lines in the next test) that appears below this?
> > > > > > It
> > > > > > would seem those would qualify as comments as well.
> > > > >
> > > > > I intentionally did not change that behavior for two reasons:
> > > > >
> > > > > a) from a Git perspective, comment characters are only effectual for
> > > > > comments
> > > > > if they are the first character in a line
> > > > >
> > > > > and
> > > > >
> > > > > b) there are places where a '#' character from the todo list is
> > > > > actually
> > > > > parsed and used e.g. [0] and [1].  I have not yet gotten to the point
> > > > > of
> > > > > grokking what is going on there, so I didn't want to risk breaking
> > > > > something I
> > > > > didn't understand.  Perhaps Johannes could shed some light on whether
> > > > > the
> > > > > cases you mentioned should be changed to use the configured
> > > > > commentChar or
> > > > > not.
> > > > >
> > > > > [0]
> > > > > https://github.com/git/git/blob/53f9a3e157dbbc901a02ac2c73346d375e24978c/sequencer.c#L2869
> > > > > [1]
> > > > > https://github.com/git/git/blob/53f9a3e157dbbc901a02ac2c73346d375e24978c/sequencer.c#L3797
> > > >
> > > > These are related. The first one tries to support
> > > >
> > > >   merge -C cafecafe second-branch third-branch # Octopus 2nd/3rd branch
> > > >
> > > > i.e. use '#' to separate between the commit(s) to merge and the oneline
> > > > (the latter for the reader's pleasure, just like the onelines in the
> > > > `pick
> > > > <hash> <oneline>` lines.
> > > >
> > > > The second ensures that there is no valid label `#`.
> > > >
> > > > I have not really thought about the ramifications of changing this to
> > > > comment_line_char, but I guess it *could* work if both locations were
> > > > changed.
> > >
> > > Is there interest in such a change?  I'm happy to take a stab at it if
> > > there
> > > is, otherwise I'll leave things as they are.
> > 
> > I think it would be a fine change, once we convinced ourselves that it
> > does not break things (I am a little worried about this because I remember
> > just how long I had to reflect about the ramifications with regards to the
> > label: `#` is a valid ref name, after all, and that was the reason why I
> > had to treat it specially, and I wonder whether allowing arbitrary comment
> > chars will require us to add more such special handling that is not
> > necessary if we stick to `#`).
> 
> Would it simpler/safer to perhaps put the oneline on its own commented line
> above?  I know it isn't quite consistent with the way onelines are displayed
> for normal commits, but it might be a worthwhile tradeoff for the sake of the
> code.  As an idea of what I am suggesting, your example above would become
> perhaps
> 
>     # Merge: Octopus 2nd/3rd branch
>     merge -C cafecafe second-branch third-branch
> 
> or perhaps just
> 
>     # Octopus 2nd/3rd branch
>     merge -C cafecafe second-branch third-branch
> 
> Thoughts?

That is a very good idea, if you ask me! Unfortunately, I forgot about
this suggestion, and IIUC v2.19.0 shipped with my previously-suggested
version.

But maybe you want to spend a little time on the code to change it
according to your suggestion?

The `merge` commands are generated here:
https://github.com/git/git/blob/v2.19.0/sequencer.c#L4096-L4120

> > Not that the comment line char feature seems to be all that safe. I could
> > imagine that setting it to ' ' (i.e. a single space) wreaks havoc with
> > Git, and we have no safeguard to error out in this obviously broken case.
> 
> Technically, I think a single space might actually work with commit messages
> (at least, I can't off the top of my head think of a case where git would
> insert a non-comment line starting with a space if it wasn't already present
> in a commit message).  But if someone were actually crazy enough to do that I
> might suggest a diagnosis of "if it hurts, don't do that" rather than trying
> to equip git defend against that sort of thing.

I did want to have an extra special visual marker for users (such as
myself), so a space would not quite be enough. That's why I settled for
the comment char.

Ciao,
Johannes