Re: pre-v2.34.0-rc0 regressions: 'git log' has a noisy iconv() warning

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> The firehose of warnings for "git log --encoding=nonsense" was known and
> discussed in fd680bc558 (logmsg_reencode(): warn when iconv() fails,
> 2021-08-27). It's ugly for sure, but I'm still OK with it for the
> reasoning there: your next step is to fix the --encoding argument you
> gave. Whether you saw one line of warning or many is not that important,
> IMHO. Giving a single more sensible warning ("your encoding 'nonsense'
> isn't valid") would be better, but I think it's hard to do without
> creating other problems.
>
> But the most compelling argument against warning at all is the case you
> gave earlier: that there may be historical garbage commits, and you
> can't get rid of them, so being warned constantly that we're not going
> to show or grep them correctly is just annoying. And that is true
> whether the user sees one warning or a hundred.

Is it really a "firehose"?  I won't use the word for one warning
message per commit in the output of "git log --encoding=nonsense".

If you are running "git log --oneline", it may indeed be annoying to
double the number of lines shown, and indeed

    $ git log --oneline --encoding=US-ASCII -4 ab/doc-lint
    warning: unable to reencode commit to 'US-ASCII'
    414abf159f docs: fix linting issues due to incorrect relative section order
    warning: unable to reencode commit to 'US-ASCII'
    ea8b9271b1 doc lint: lint relative section order
    warning: unable to reencode commit to 'US-ASCII'
    cafd9828e8 doc lint: lint and fix missing "GIT" end sections
    warning: unable to reencode commit to 'US-ASCII'
    d2c9908076 doc lint: fix bugs in, simplify and improve lint script

is indeed annoying, as everything that is _shown_ ought to be
presentable in US-ASCII.  This observation makes us realize an
obvious approach to improve over the current behaviour without
losing the warning when it matters, but I think the required code
change, to first split the commit message into pieces (which roughly
corresponds to the atoms in the --format= placeholder language) and
reencode only these pieces that will be shown, may be too involved
to be worth the effort.

> So while I do hate to have Git just silently ignore errors, probably the
> original behavior is the least-bad thing, and we should just revert
> fd680bc558 (logmsg_reencode(): warn when iconv() fails, 2021-08-27). We
> probably want to salvage the documentation change (minus the "along with
> a warning") part.

I am all for making it convenient to squelch, but it would be sad to
lose the convenient way to notice possible misencoding in recent
commits.  Or can we have a command line option and pass it through
the callchain, or would that be too involved?