Re: allow "~" to be present in a tag name

[Michal Novotny <clime@redhat.com>]

On Tue, Mar 13, 2018 at 10:07 AM, Ævar Arnfjörð Bjarmason
<avarab@gmail.com> wrote:
>
> On Tue, Mar 13 2018, Michal Novotny jotted:
>
>> Hello,
>>
>> currently, if I try to create a tag that has tilde "~"  in name, an
>> error is raised. E.g.
>>
>> $ git tag rpkg-util-1.4~rc1
>> fatal: 'rpkg-util-1.4~rc1' is not a valid tag name.
>>
>> Now, actually it would be very cool if tilde was allowed in a tag name
>> because we would like to use it for tagging pre-releases of (not-only
>> rpm) packages.
>>
>> Is there some deep technical reason why tilde cannot be present in a
>> tag name? I tried that e.g.
>
> Yes, because a trailing tilde is part of git's rev syntax, see "man
> git-rev-parse", or try in any repo:
>
>     git show HEAD
>     git show HEAD~2
>     git show HEAD^~2

Right, reading the man pages:

<rev>~<n>, e.g. master~3
           A suffix ~<n> to a revision parameter means the commit
object that is the <n>th generation ancestor of the named commit
object, following only the first
           parents. I.e.  <rev>~3 is equivalent to <rev>^^^ which is
equivalent to <rev>^1^1^1. See below for an illustration of the usage
of this form.

Would it be acceptable to disallow only ~<n> (<n> as [0-9]+) in a tag
name but allow ~[^0-9].*, i.e. if the immediately following symbol
after '~' is a letter, do not
interpret ~ as a special character. Could it work?

Thank you!
clime

>
> etc.
>
> Although I guess git could learn to disambiguate that form from the tag
> you're trying to create.
>
>> git tag rpkg-util-1.4%rc1
>>
>> but percentage sign does not seem to be particular fitting for
>> pre-release marking.
>>
>> Thank you
>> clime