Re: [RFC PATCH 0/4] interpret-trailers: introduce "move" action

[Paolo Bonzini <pbonzini@redhat.com>]

On 06/10/2017 12:30, Christian Couder wrote:
> On Thu, Oct 5, 2017 at 3:22 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> The purpose of this action is for scripts to be able to keep the
>> user's Signed-off-by at the end.  For example say I have a script
>> that adds a Reviewed-by tag:
>>
>>     #! /bin/sh
>>     them=$(git log -i -1 --pretty='format:%an <%ae>' --author="$*")
>>     trailer="Reviewed-by: $them"
>>     git log -1 --pretty=format:%B | \
>>       git interpret-trailers --where end --if-exists doNothing --trailer "$trailer" | \
>>       git commit --amend -F-
>>
>> Now, this script will leave my Signed-off-by line in a non-canonical
>> place, like
>>
>>    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>    Reviewed-by: Junio C Hamano <gitster@pobox.com>
>>
>> This new option enables the following improvement:
>>
>>     #! /bin/sh
>>     me=$(git var GIT_COMMITTER_IDENT | sed 's,>.*,>,')
>>     them=$(git log -i -1 --pretty='format:%an <%ae>' --author="$*")
>>     trailer="Reviewed-by: $them"
>>     sob="Signed-off-by: $me"
>>     git log -1 --pretty=format:%B | \
>>       git interpret-trailers --where end --if-exists doNothing --trailer "$trailer" \
>>                              --where end --if-exists move --if-missing doNothing --trailer "$sob" | \
>>       git commit --amend -F-
>>
>> which lets me keep the SoB line at the end, as it should be.
>> Posting as RFC because it's possible that I'm missing a simpler
>> way to achieve this...
> 
> Did you try using `--where end --if-exists replace --trailer "$sob"`?

Yes, it's a different behavior; "--if-exists replace" matches on others'
SoB as well, so it would eat the original author's SoB if I didn't have one.

So "move" does get it wrong for

    Signed-off-by: Me
    Signed-off-by: Friend

(Me gets moved last, which may not be what you want) but "replace" gets
it wrong in the arguably more common case of

    Signed-off-by: Friend

which is damaged to just "Signed-off-by: Me".

Paolo