Re: [RFC PATCH] revision: new rev%n shorthand for rev^n..rev

Vegard Nossum [off-list ref] writes:

I use rev^..rev daily, and I'm surely not the only one. To save typing
(or copy-pasting, if the rev is long -- like a full SHA-1 or branch name)
we can make rev% a shorthand for that.

No, we cannot.

'%' is not reserved as a special character that is forbidden in
reference names, and for somebody who has a branch whose name is
'master%', such a change will suddenly make 'master%' mean something
completely different, breaking existing users' repositories.

This is why existing rev^@ and rev^! both use the "^" as the first
character that introduces the "magic" semantics; "^" cannot be a
part of a refname.  Also sequences that begin with "^{" and "@{" are
reserved as escape hatches to allow us extend the revision syntax in
the future ("^{" works on history, while "@{" bases its working on
the reflog data).

As "rev^$n" is "nth parent", it may be a possibility to use "rev^-$n"
as a short-hand for "^rev^$n rev".