Q: "git diff" using tag names

> Hi,
> 
> when using a somewhat older git (of SLES11 SP1 SDK), I could not find
> a way to "git diff" between two tag names; I can only diff between
> two commit numbers. I can display a changeset using "git show", but
> that's not what I wanted. Is it possible to get the diff I want using
> older versions, and is such a feature implemented in the current
> version? If so, since when?
> 
> As I'm not subscribed to the list, I'd appreciate CC'ed replies.
> Thank you.
> 
> Greeting
> Ulrich
> 
> 

> Tag is a pointer to a commit (if to say simply)
> 
> e.g. in my repo
> $ git show-ref --tags --abbrev=7
> -->8--
> 676f194 refs/tags/v2.6.7
> b23c481 refs/tags/v2.6.8
> -->8--
> 
> so
> 
> $ git diff v2.6.7..v2.6.8
> is equivalent to
> $ git diff 676f194..b23c481
> 
> etc
> > Hi,
> > 
> > when using a somewhat older git (of SLES11 SP1 SDK), I could not find
> > a way to "git diff" between two tag names; I can only diff between
> > two commit numbers. I can display a changeset using "git show", but
> > that's not what I wanted. Is it possible to get the diff I want using
> > older versions, and is such a feature implemented in the current
> > version? If so, since when?
> > 
> > As I'm not subscribed to the list, I'd appreciate CC'ed replies.
> > Thank you.
> > 
> > Greeting
> > Ulrich
> > 
> > 
> 
> 

> Hello Alexey,
> 
> thank you very much for your reply. I felt I did something wrong, but
> couldn't find out what it was. Actually it turned out that I had just
> mistyped one tag name.
> 
> Also it seems that both syntaxes work:
> git diff v0.4..v0.5
> git diff v0.4 v0.5
> 
> The question is: How does git disambiguate between tag names, commits
> and file names? (All may start with a letter) This seems to work
> automagically, and I was desparately looking for an option like "--"
> to separate revisions from file names. I found "SPECIFYING REVISIONS"
> in git-rev-parse(1), so you don't really have to answer.

> 
> Regards,
> Ulrich
> 
> >>> Alexey Shumkin <Alex.Crezoff@gmail.com> schrieb am 28.10.2011 um
> >>> 14:59 in
> Nachricht <20111028165943.2cc8253d@ashu.dyn.rarus.ru>:
> > Tag is a pointer to a commit (if to say simply)
> > 
> > e.g. in my repo
> > $ git show-ref --tags --abbrev=7
> > -->8--
> > 676f194 refs/tags/v2.6.7
> > b23c481 refs/tags/v2.6.8
> > -->8--
> > 
> > so
> > 
> > $ git diff v2.6.7..v2.6.8
> > is equivalent to
> > $ git diff 676f194..b23c481
> > 
> > etc
> > > Hi,
> > > 
> > > when using a somewhat older git (of SLES11 SP1 SDK), I could not
> > > find a way to "git diff" between two tag names; I can only diff
> > > between two commit numbers. I can display a changeset using "git
> > > show", but that's not what I wanted. Is it possible to get the
> > > diff I want using older versions, and is such a feature
> > > implemented in the current version? If so, since when?
> > > 
> > > As I'm not subscribed to the list, I'd appreciate CC'ed replies.
> > > Thank you.
> > > 
> > > Greeting
> > > Ulrich
> > > 
> > > 
> > 
> > 
> 
>  
>  
> 

>> Also it seems that both syntaxes work:
>> git diff v0.4..v0.5
>> git diff v0.4 v0.5
> honestly, I do not know the difference (at the moment :))
> may be gurus or manual will help to discover it

> On Wed, Nov 2, 2011 at 10:29 AM, Alexey Shumkin
> <alex.crezoff@gmail.com> wrote:
> 
> >> Also it seems that both syntaxes work:
> >> git diff v0.4..v0.5
> >> git diff v0.4 v0.5
> > honestly, I do not know the difference (at the moment :))
> > may be gurus or manual will help to discover it
> 
> As per the git-diff documentation, these two versions behave equally
> -- i.e. no differences.
> 
> Comparing branches
> $ git diff topic master    <1>
> $ git diff topic..master   <2>
> $ git diff topic...master  <3>
> ‪1.‬ Changes between the tips of the topic and the master branches.
> ‪2.‬ Same as above.
> ‪3.‬ Changes that occurred on the master branch since when the topic
> branch was started off it.
> 
> Cheers,
> Frans

>> Also it seems that both syntaxes work:
>> git diff v0.4..v0.5
>> git diff v0.4 v0.5
> honestly, I do not know the difference (at the moment :))
> may be gurus or manual will help to discover it

> Alexey Shumkin <alex.crezoff@gmail.com> writes:
> 
> >> Also it seems that both syntaxes work:
> >> git diff v0.4..v0.5
> >> git diff v0.4 v0.5
> > honestly, I do not know the difference (at the moment :))
> > may be gurus or manual will help to discover it
> 
> The latter is the kosher version, as diff is about two "endpoints"
> and not about "ranges". The only reason the former is parsed without
> erroring out is because too many people are used to type .. between
> two things without thinking, learned the notation from "git log",
> which _is_ about ranges.

>                                                      I could not
> find a way to "git diff" between two tag names; I can only diff
> between two commit numbers. I can display a changeset using "git
> show", but that's not what I wanted.
>
> Is it possible to get the diff I want using older versions, and is
> such a feature implemented in the current version? If so, since
> when?

> "Ulrich Windl" <Ulrich.Windl@rz.uni-regensburg.de> writes:
> 
> > When using a somewhat older git (of SLES11 SP1 SDK),
> 
> Nb. you can check version of git with "git --version".

> 
> >                                                      I could not
> > find a way to "git diff" between two tag names; I can only diff
> > between two commit numbers. I can display a changeset using "git
> > show", but that's not what I wanted.
> >
> > Is it possible to get the diff I want using older versions, and is
> > such a feature implemented in the current version? If so, since
> > when?
> 
> From the very beginning in Git you can use tag name where you need
> commit identifier; Git would use commit that tag points to (will
> dereference or peel a tag).

> 
> That is not possible in some [censored] version control systems; I am
> looking at you, Subversion!
> 
> 
> So if you can do
> 
>   $ git show v0.9
>   $ git show v1.0
> 
> you can also do
> 
>   $ git diff v0.9 v1.0
> 
> and
> 
>   $ git log v0.9..v1.0