Re: [PATCH 2/2] rebase: `preserve` is also a pull option, tell dying users

From: Philip Oakley <philipoakley@iee.email>
Date: Feb 22, 2022, 15:56 UTC
Message-ID: <3e144b59-dce2-ce10-cd9b-eca92eee922c@iee.email>
In-Reply-To: <220222.868ru27vtt.gmgdl@evledraar.gmail.com>

On 22/02/2022 15:34, Ævar Arnfjörð Bjarmason wrote:

Show 49 quoted lines

> On Tue, Feb 22 2022, Philip Oakley via GitGitGadget wrote:
>
>> From: Philip Oakley <philipoakley@iee.email>
>>
>> The `--preserve-merges` option was removed by v2.35.0. However
>> users may not be aware that it is also a Pull option, and it is
>> still offered by major IDE vendors such as Visual Studio.
>>
>> Extend the `--preserve-merges` die message to direct users to
>> this option and it's locations.
>>
>> Signed-off-by: Philip Oakley <philipoakley@iee.email>
>> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
>> ---
>>  builtin/rebase.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/builtin/rebase.c b/builtin/rebase.c
>> index 07221d0ae41..97f704bb297 100644
>> --- a/builtin/rebase.c
>> +++ b/builtin/rebase.c
>> @@ -1205,7 +1205,10 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>>  			     builtin_rebase_usage, 0);
>>  
>>  	if (preserve_merges_selected)
>> -		die(_("--preserve-merges was replaced by --rebase-merges"));
>> +		die(_("--preserve-merges was replaced by --rebase-merges\n"
>> +			"Also, check your `pull` configuration settings\n"
>> +			"`git config --show-scope --show-origin --get-regexp 'pull.*'`\n"
>> +			"which may also invoke this option."));
> I may be missing some subtlety, but how is the user ever going to need
> to check their config?
>
> After 52f1e82178e (pull: remove support for `--rebase=preserve`,
> 2021-09-07) we:
>
>     $ git -c pull.rebase=preserve pull
>     error: rebase.c:29: preserve: 'preserve' superseded by 'merges'
>     fatal: builtin/pull.c:45: Invalid value for pull.rebase: preserve
>
> I.e. we'd error before this, and the "preserve_merges_selected" variable
> being checked here is not affected by config, i.e. we only ever got to
> this "via config" route if "pull" et al was invoking us.
>
> But now that command dies.
>
> If there is still a codepath where we call "rebase --preserve-merges" on
> the basis of config that I've missed, shouldn't this die() be happening
> there?

Hi Ævar,

The preserve merges is a pull config item, still supported by Visual Studio, so could easily be set for many users. When they click on the "Pull" menu and get the old die() fatal: message they won't know why this happened or how to resolve it. Hence the extra info.

If the user was actually running a rebase command then, yes, they would/should be reasonably OK with the original error message telling them what was wrong with their command line. But a `git pull`? especially as the manual says nothing about preserve merges any more.

If we are to remove a capability the `give up and die` messages should be helpful in the edge cases. The issue (needing to check the pull, as well as the rebase configs) has already shown on the git-users list. It took a while to workout how it all happened.

Not sure if I've covered your concerns properly, but this is one of the places that can and warn the user.

Philip