Re: Questions about trailer configuration semantics

From: Anders Waldenborg <anders@0x63.nu>
Date: Jul 27, 2020, 22:57 UTC
Message-ID: <875za8r2fu.fsf@0x63.nu>
In-Reply-To: <20200727194036.GA795313@coredump.intra.peff.net>

Jeff King writes:

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> On Mon, Jul 27, 2020 at 08:37:26PM +0200, Christian Couder wrote:
>
>> > > I noticed some undocumented and (at least to me) surprising behavior in
>> > > trailers.c.
>> > >
>> > > When configuring a value in trailer.<token>.key it causes the trailer to
>> > > be normalized to that in "git interpret-trailers --parse".
>> > > E.g:
>> > >  $ printf '\naCKed: Zz\n' | \
>> > >    git -c 'trailer.Acked.key=Acked' interpret-trailers --parse
>> > >  will emit: "Acked: Zz"
>>
>> Yeah, I think that's nice, as it can make sure that the key appears in
>> the same way. It's true that it would be better if it would be
>> documented.
>
> I'd note that this also happens without --parse.

Right, and it also happens with "--only-input" (part of "--parse")

"--only-input" is documented as follows:

   Output only trailers that exist in the input; do not add any from the
   command-line or by following configured trailer.* rules.

[]

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> I don't recall being aware of this prefix matching until this thread, so
> I doubt that the current behavior of --parse was something I tried for
> intentionally. It's mostly just using the existing code, plus a few
> extra options (listed in the docs). I'm not opposed to adding an option
> to do strict matching and/or avoid rewriting, and then possibly adding
> that into --parse by default.

Would that option also be set for the parsing done by "%(trailers)" pretty format specifier?

> I don't have much of an opinion on which behavior would be preferred.
> I've never actually had a use case for configuring trailer.*.key, as I
> usually am only looking at reading existing trailers to collect stats,
> etc.

I'm also mainly using in reading trailers (mostly with pretty format "%(trailers:key=x)") and then these convenience shortcuts doesn't really seem helpful, they rather add a small risk of mangling my data. Not that this has caused any problems for me in practice.