On 1/21/2020 11:24 AM, Jeff King wrote:
> On Tue, Jan 21, 2020 at 01:38:12AM +0000, Derrick Stolee via GitGitGadget wrote:
>
>> Update the documentation to clarify how '--refmap=""' works and
>> create tests to guarantee this behavior remains in the future.
>
> Yeah, this looks like a good solution to me.
>
>> This can be accomplished by overriding the configured refspec using
>> '--refmap=' along with a custom refspec:
>>
>> git fetch <remote> --refmap= +refs/heads/*:refs/hidden/<remote>/*
>
> This isn't strictly related to your patch, but since the rationale here
> describes the concept of a background job and people might end up using
> it as a reference, do you want to add in --no-tags to help them out?
That's a good idea. I keep forgetting about that. It's interesting that
tags are fetched even though my refpsec does not include refs/tags.
>> Thanks for all the feedback leading to absolutely no code change. It's
>> good we already have the flexibility for this. I'm a bit embarrassed
>> that I did not discover this, so perhaps this doc change and new tests
>> will help clarify the behavior.
> Anyway, I wasn't at all sure that a blank --refmap= would do what you
> want until I tried it. But it was always intended to work that way. From
> c5558f80c3 (fetch: allow explicit --refmap to override configuration,
> 2014-05-29):
>
> +static int parse_refmap_arg(const struct option *opt, const char *arg, int unset)
> +{
> + ALLOC_GROW(refmap_array, refmap_nr + 1, refmap_alloc);
> +
> + /*
> + * "git fetch --refmap='' origin foo"
> + * can be used to tell the command not to store anywhere
> + */
> + if (*arg)
> + refmap_array[refmap_nr++] = arg;
> + return 0;
> +}
>
> At first I thought the comment was wrong, since we don't actually
> increment refmap_nr. But the ALLOC_GROW makes refmap_array non-NULL,
> which is what triggers the "do not use configured refspecs" logic.
This works due to a subtle arrangement of things, like a non-NULL
but "empty" array. That justifies the test even more.
> This code switched to refspec_append() in e4cffacc80 (fetch: convert
> refmap to use struct refspec, 2018-05-16), and I think we actually do
> push an empty string onto the list. Which then triggers the "do not use
> configured refspecs" logic, but doesn't match anything itself. I'm not
> sure whether that behavior was entirely planned, or just what the code
> happens to do. So it's doubly useful to add a test here covering the
> expected behavior.
Excellent. Glad I'm not just adding test bloat for now reason.
-Stolee
