git describe --match returns wrong tag name if commit has two tags

Question

I'm trying to add an extra tag for the commit to be able later to select this commit by git describe with --match pattern;

When I use --match to catch usual commits with one tag everything works fine.

But when I try to --match commit with two tags by pattern "deployed", I get very weird tag like, for example:

I have commit: b946bdf (tag: [email protected]) Publish

I add "deployed" tag: b946bdf (tag: [email protected], tag: deployed) Publish

Then I run git describe --abbrev=0 --match "deployed"

And the result of this command is [email protected]

If I try to use --abbrev=1 I get [email protected]

And the most interesting that the -9-g1e5c94cc55fded72114b801bd47d8d29e7721255 is not even a has of this commit. I have no idea why and where from I get this weird identifier.

I want to get a clean tag like [email protected]

What I'm doing wrong?

Answer 1

The --match option to git describe takes a shell-style glob pattern, such as a*z. It then runs the tags listed by git tags through a shell-style matcher.¹ Hence, given the glob pattern a*z, tags named abuzz and aveloz would match, but a tag named arbiter or fuzz would not.

Your glob pattern is deployed, and since there are no wildcard characters allowed, the only allowed tag by this --match option is deployed itself. You do have a tag named deployed, and you gave only one --match, so this is the only one allowed.

If I create such a tag, I can use it:

$ git tag -a deployed -m silly
$ git describe --abbrev=0 --match deployed
deployed

This tag can't be used for any earlier revision, of course:

$ git describe --abbrev=0 --match deployed HEAD~
fatal: No tags can describe '98f3f03bcbf4e0eda498f0a0c01d9bd90de9e106'.
Try --always, or create some tags.

Deleting the tag produces an appropriate error:

$ git tag -d deployed
Deleted tag 'deployed' (was a464a376ca)
$ git describe --abbrev=0 --match deployed 
fatal: No names found, cannot describe anything.

I cannot explain your output. There have been bugs in git describe; the release notes for Git 2.15.0 point one out, for instance. But this would not produce the output you show (I think). What version of Git are you using?

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¹This is actually all built in to git describe itself, which doesn't have to run git tags. The effect is the same, though. Note that shell glob patterns may need quoting to protect them from the shell, depending on your shell.

Answer 2

If your intention is to get the hash of the commit tagged by deployed, just use git rev-parse :

# works for any type of tag :
git rev-parse deployed^{}

# works if 'deployed' is a plain tag :
git rev-parse deployed

If deployed is an annotated tag, git rev-parse deployed (without the ^{}) will give you the hash of the tag object itself, not the hash of the commit that is tagged.

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this doesn't explain the weird output you get from git describe, but I thought it was worth mentioning this command.