Re: [PATCH 2/3] name-rev: strip trailing ^0 in when --name-only

Junio C Hamano [off-list ref] writes:

WRT "describe --contains", I do agree that both of these

    $ git describe $(git rev-parse v1.8.3^0)
    $ git describe --contains $(git rev-parse v1.8.3^0)
        
should just say "v1.8.3" without ~0/^0/~0~0~0 etc. and the last
example you showed will be improved by dropping ^0 at the end.

However.

I was a bit bothered by the description talking _only_ about
describe, but the actual change is to modify what name-rev gives its
direct users as well.  And that made me realize that the patch
itself has an undesirable side effect.

"describe" is _only_ about commit history graph, so in its context
v1.8.3 means the same thing as v1.8.3^0 (we never want to get a tag;
we always want a commit).  But I do not think "name-rev" is limited
to commits, in the sense that you would see this:

    $ git rev-parse v1.8.3 v1.8.3^0 | git name-rev --stdin
    8af06057d0c31a24e8737ae846ac2e116e8bafb9
    edca4152560522a431a51fc0a06147fc680b5b18 (tags/v1.8.3^0)

The second object is _not_ v1.8.3 but is v1.8.3^0 in the context of
name-rev, whose purpose is to give you a string you can feed
"rev-parse" and get the object name back.  "rev-parse v1.8.3" will
not give you the commit object name, so you need to keep "^0".

Well, the code in "name-rev" other than --stdin mode is already
broken (and the documentation half-describes this breakage) in that
it describes the peeled commit and rejects anything other than
commit objects.  The reason I say "half-describes" is that it only
says that the command takes "commit-ish" and leaves it unclear if it
comes up with a name for the tag itself that happens to be
commit-ish, or it does so for the commit that is referred by the
tag.

I'll send out a WIP to fix that, and also help the topic to strip
unnecessary "^0" suffix when name-rev is run as an implementation
detail of "describe" shortly.