Re: [PATCH] show-ref: Allow --head to work with --verify

Vladimir Panteleev [off-list ref] writes:

Hi Junio,

On 2017-01-20 19:03, Junio C Hamano wrote:

quoted

Having said all that, using --verify on HEAD does not make much
sense, because if HEAD is missing in .git/, I do not think Git
considers that directory as a Git repository to begin with.  So from
that point of view, I am not sure what value this change adds to the
system, even though the change is almost correct (modulo the "quiet"
thing).

My use case was the following series of steps:

Q1: How do I resolve a full ref name to a commit SHA1?
A1: Use show-ref <full-ref-name>.

Q2: How to make git show-ref also work when HEAD is specified as the
reference?
A2: Add --head.

Q3: How do I make git show-ref only look for the exact full ref name
specified, instead of doing a pattern/substring search, and thus
output at most one result?
A3: Add --verify.

However, A2 and A3 are incompatible. Thus, there doesn't seem to be a
way to e.g. make a simple alias which looks up a ref only by its full
ref name, where said ref might or might not be HEAD. The obvious
workaround is to check if the ref is HEAD in the rev-parse caller,
however it seemed more logical to fix it in git instead.

The documentation for show-ref also makes no mention that --head is
ignored if --verify is specified, and the combination was not covered
by any tests, therefore this seemed to me as a simple omission in
--verify's logic.

There is also rev-parse, which also has a --verify switch, however it
does something else, and I don't see a way to ask rev-parse to only
consider full refs.

Your log message for the patch needs to be updated by summarizing
the above better.  I couldn't read the motivation behind the change
fully from the original (even though I guessed it correctly).