Re: [RFC PATCH] fast-export, fast-import: Let tags specify an internal name

[Luke Shumaker <lukeshu@lukeshu.com>]

On Wed, 21 Apr 2021 12:34:26 -0600,
Elijah Newren wrote:
> On Wed, Apr 21, 2021 at 1:19 AM Ævar Arnfjörð Bjarmason
> <avarab@gmail.com> wrote:
> > There's also perfectly legitimate in-the-wild use-cases for this,
> > e.g. "archiving" tags to not-refs/tags/* so e.g. the upload-pack logic
> > doesn't consider and follow them. Not being able to export/import those
> > repositories as-is due to an overzelous data check there that's not in
> > fsck.c would suck.
> 
> Not would suck, but does suck.  I had to document it as a shortcoming
> of fast-export/fast-import -- see
> https://www.mankier.com/1/git-filter-repo#Internals-Limitations, where
> I wrote, "annotated and signed tags outside of the refs/tags/
> namespace are not supported (their location will be mangled in weird
> ways)".
> 
> The problem is, what's the right backward-compatible way to fix this?
> Do we have to add a flag to both fast-export and fast-import to stop
> assuming a "refs/tags/" prefix and use the full refname, and require
> the user to pass both flags?  How is fast-import supposed to know that
> "refs/alternate-tags/foo" is or isn't
> "refs/tags/refs/alternate-tags/foo"?
> 
> And if we need such a flag, should fast-import die if it sees this new
> "name" directive and the flag isn't given?

Elsehwere in the thread, I responded to some feedback by suggesting
that perhaps I should flip it around, and instead add a 'refname'
sub-command, and have it default to 'refs/tags/{tagname}'

So the stream

    tag foo
    ...

would create a tag at "refs/tags/foo" that says "tag foo".  And the
stream

    tag bar
    refname refs/alternate-tags/baz

would create a tag at "refs/alternate-tags/baz" that says "tag bar".

Grepping for "refs/tags" in fast-export.c and fast-import.c, I think
that would fully address this concern.

-- 
Happy hacking,
~ Luke Shumaker