Re: [PATCH v3 2/3] git-push: clean up some of the output from git push --porcelain

On Mon, Feb 08, 2010 at 02:21:26PM -0800, Junio C Hamano wrote:

I think the purpose of the patches that started this thread was to admit
that 1965ff7 (add --porcelain option to git-push, 2009-06-22) was not well
thought out, and to break compatibility to fix it.

I thought it was simply to remove stdout cruft that had crept in, and at
the same time to remove some stderr cruft that was simply noise on the
terminal. That being said, I am in favor of fixing it even if it means a
slight compatibility breakage.

Having said that, I would say that what 1965ff7 specified was only these
two:

    = TAB refs/heads/master:refs/heads/master TAB [up to date]
    - TAB :refs/heads/foobar TAB [deleted]

so everything else that do not match this pattern is a fair game, most
importantly, the line that begins with "To" would not be mistaken with
this pattern, I think.

It depends on the parser. If the parser was something like:

  switch (line[0]) {
    case '=': ...; break;
    case '-': ...; break;
    default: die("wtf: %s", line);
  }

then we are not introducing any ambiguity, but we are causing a
breakage. The problem is that we did not specify the format anywhere, so
it is hard to say whether we are breaking any promises we made.

quoted

This one, on the other hand, seems to me to be just noise. What does a
--porcelain caller learn by seeing "Everything up-to-date" that it did
not already know from seeing the list of refs?

I do not care too much about this hunk either way.  We could leave it as
is, as we will be giving some other stuff to the standard error stream
without squelching anyway, even with the three-patch series.  We could
squelch only this message, but it is dubious what it is buying us.  If you
forced me to decide, I would probably say "let's just drop this hunk and
keep the code as-is".

I have not actually been running these patches, just reading them, but
my impression was the goal _was_ to squelch all of the stderr cruft. But
if we are not even close, then probably we should just give up and
callers should "2>/dev/null".

As to the exit status, do you have any thoughts, by the way?

I am not convinced that it would be necessary nor even a good idea to make
it behave inconsistently between the normal case and Porcelain case, only
to make it easier to special case the "remote side would reject due to
non-fast-forward" failure mode (iow, even if the calling script knows that
it would fail due to non-fast-forward but otherwise everything else would
be fine, what good would it do?)

I had initially endorsed it, but now I am having second thoughts.
Especially if the "usual" calling convention is to redirect stderr as
above, then we are probably missing out on any useful error messages
that accompany a failure return, anyway.  So maybe the sane thing to do
is to leave the exit code alone, and include a --porcelain output line
that either says "Everything was OK, see individual ref status" or "We
couldn't even talk to the other side". Then the status code is
irrelevant, and stdout contains all of the useful information (and if
you don't get an error or OK message, you know there was some
serious error like a broken git installation).

-Peff