Doug Bell <madcityzen@xxxxxxxxx> writes:
> The docs seem to say that doing
>
> git show-ref --head --tags
>
> would show both the HEAD ref and all the tag refs. However, doing
> both --head and either of --tags or --heads would filter out the HEAD
> ref.
>
> Signed-off-by: Doug Bell <madcityzen@xxxxxxxxx>
> ---
I think this patch fell through the cracks, and looking at it, I am
somewhat torn.
The command help for "--head" says "show the HEAD reference", which
may mean:
(1) in addition to everything else the command would do if there
weren't this option specified, show HEAD;
(2) show the HEAD and nothing else; or
(3) add HEAD to the candidates to be shown, but apply the usual
filtering rule based on --heads, --tags and/or pattern
arguments.
While the last interpretation is what we have used since the
beginning of the command at 358ddb62 (Add "git show-ref" builtin
command, 2006-09-15), I tend to agree with you that the first
interpretation may make more sense, at least from the end user's
point of view.
But at a deeper level, it makes the command somewhat inconsistent.
What happens in the command is
- We iterate over "candidates to be shown", which is usually
"everything under refs/", but with "--head", HEAD is added to
this set. For each of these candidates:
- if one or more <pattern> parameters are given, reject the
candidate ref if it does not tail-match with any of the
patterns;
- if either "--heads" or "--tags" is given, among the ones that
pass <pattern> filter, check if they:
- begin with "refs/heads/" (if "--heads" is given); or
- begin with "refs/tags/" (if "--tags" is given).
and reject those that don't.
- show it if it is still surviving after these two tests.
And taht is why "git show-ref --tags master v1.3.0" shows only the
v1.3.0 tag without showing the master branch, and giving "--heads"
instead of "--tags" yields only the master branch without the tag.
The semantics your patch wants, by changing the definition of
"--head" from (3) to (1), is:
- If "--head" is given, show HEAD no matter what.
- Iterate over everything under refs/, and for each of them, do the
same filter-and-show as we currently do (see above).
While I think the new semantics is also understandable as the
current one, and personally I think it is a better behaviour than
the current one, it will require an update to the document to
highlight that "--head" is special-cased in a big way, to bypass all
the filtering that is applied to normal refs.
A few additional observations (these are not complaints to this
patch and please do not take them as such):
- The command help says "(can be combined with heads)" for "--tags"
and vice versa, but does not mention their interaction with
"--head". This is because we take interpretation (3) above and
do not treat "--head" as a mechanism to add to <pattern>
parameter like these two.
- The command help for "--heads" and "--tags" says "only show
heads/tags", which technically does not contradict with "can be
combined with" above, but a logical consequence of combining
ought to be showing nothing, as a ref cannot be a head (an old
nomenclature for a "branch") and a tag at the same time.
I think we should find a word better than "only" to use here, but I
am not sure what would be a good phrase to use.
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