Re: [PATCH] git-filter-branch could be confused by similar names

[Junio C Hamano <gitster@pobox.com>]

Dmitry Potapov <dpotapov@gmail.com> writes:

> 'git-filter-branch branch' could fail producing the error:
> "Which ref do you want to rewrite?" if existed another branch
> or tag, which name was 'branch-something' or 'something/branch'.
>
> Signed-off-by: Dmitry Potapov <dpotapov@gmail.com>
> ---
>
> I have corrected my previous patch to allow "heads" or "tags"
> in the name of a branch or tag, i.e. to write it like this:
>    git filter-branch heads/master
>
>  git-filter-branch.sh     |    2 +-
>  t/t7003-filter-branch.sh |   10 ++++++++++
>  2 files changed, 11 insertions(+), 1 deletions(-)
>
> diff --git a/git-filter-branch.sh b/git-filter-branch.sh
> index dbab1a9..5de8b12 100755
> --- a/git-filter-branch.sh
> +++ b/git-filter-branch.sh
> @@ -219,7 +219,7 @@ do
>  	;;
>  	*)
>  		ref="$(git for-each-ref --format='%(refname)' |
> -			grep /"$ref")"
> +			grep '^refs/\([^/]\+/\)\?'"$ref"'$')"
>  	esac

Do we assume everybody's grep groks ERE these days?  I had an
impression that we try to stick to a subset of BRE (namely, no
\{m,n\}, [::], [==], nor [..]).

Also as a general rule when dealing with refname, we use
fileglob not regex.

What's the goal here?  Is it to make sure given refname is
unambiguous by being a unique suffix of tags or heads, as in

	test $(git show-ref "$ref" | wc -l) = 1

or is there anything more going on?

Ah, it also wants the full name of the ref.  How about...

	ref=$(git show-ref "$ref" | sed -e 's/^.* //')

and have the "git check-ref-format" that comes later to issue an
error message?        

A better error message would be obtained with perhaps doing

	LF='
        '
        
at the beginning and then doing:

	candidate=$(git show-ref "$ref" | sed -e 's/^.* //')
	case "$candidate" in
        '')
        	die "should not happen -- $ref did not match?"
                ;;
        ?*"$LF"?*)
		die "$ref is ambiguous, which one of: $canidate?"
		;;
	esac
        ref=$candidate