Re: [PATCH 1/2] commit: add message options for rebase --autosquash

[Pat Notz <patnotz@gmail.com>]

On Fri, Sep 17, 2010 at 2:36 AM, Stephen Boyd <bebarino@gmail.com> wrote:
> On 09/16/2010 06:39 PM, Pat Notz wrote:
>> These options make it convenient to construct commit messages for use
>> with 'rebase --autosquash'.  The resulting commit message will be
>> "fixup! ..." or "squash! ..." where "..." is the subject line of the
>> specified commit message.
>>
>> Example usage:
>>   $ git commit --fixup HEAD~2
>>   $ git commit --squash HEAD~5
>>
>> Signed-off-by: Pat Notz <patnotz@gmail.com>
>> ---
>
> So far I've been using an alias for these, but I suppose making them
> real features of git could be worthwhile. What are the benefits with
> this approach vs. an alias?

Mainly it's convenience.  The rebase --autosquash feature seems too
hard to use without this or an alias and making everyone code their
own alias seems a lot to ask.

Still, I admit that I was concerned with adding yet another option to
git-commit.  If enough people object, I can live with that.

>> @@ -863,7 +871,7 @@ static int parse_and_validate_options(int argc, const char *argv[],
>>       if (force_author && renew_authorship)
>>               die("Using both --reset-author and --author does not make sense");
>>
>> -     if (logfile || message.len || use_message)
>> +     if (logfile || message.len || use_message || fixup_message || squash_message)
>>               use_editor = 0;
>>       if (edit_flag)
>>               use_editor = 1;
>
> The whole point of squash is to combine two commit texts, right?
> Otherwise wouldn't you use --fixup where you throw away the text
> eventually and thus don't want to open an editor?

Good point.  Admittedly, I was focusing on the 'fixup' case but squash
needs to open the editor with the first line pre-filled.

>
>> @@ -883,15 +891,19 @@ static int parse_and_validate_options(int argc, const char *argv[],
>>               f++;
>>       if (edit_message)
>>               f++;
>> +     if (fixup_message)
>> +             f++;
>> +     if (squash_message)
>> +             f++;
>>       if (logfile)
>>               f++;
>>       if (f > 1)
>> -             die("Only one of -c/-C/-F can be used.");
>> +             die("Only one of -c/-C/-F/--fixup/--squash can be used.");
>>       if (message.len && f > 0)
>> -             die("Option -m cannot be combined with -c/-C/-F.");
>> +             die("Option -m cannot be combined with -c/-C/-F/--fixup/--squash.");
>
>
> Furthering that point, perhaps I want to squash this commit into another
> commit using the commit text from yet another commit or just with an
> extra note from the command line (-m). Perhaps this is where the benefit
> over an alias comes in?

That's a good use-case.  I'll re-work the --squash option.

>
>>       if (edit_message)
>>               use_message = edit_message;
>> -     if (amend && !use_message)
>> +     if (amend && (!use_message && !fixup_message && !squash_message))
>>               use_message = "HEAD";
>>       if (!use_message && renew_authorship)
>>               die("--reset-author can be used only with -C, -c or --amend.");
>> @@ -932,6 +944,23 @@ static int parse_and_validate_options(int argc, const char *argv[],
>>               if (enc != utf8)
>>                       free(enc);
>>       }
>> +     if (fixup_message || squash_message) {
>> +             unsigned char sha1[20];
>> +             struct commit *commit;
>> +             const char * target_message = fixup_message ? fixup_message : squash_message;
>> +             const char * msg_fmt = fixup_message ? "fixup! %s" : "squash! %s";
>
> Style nit: stick the * to the variable.
>

Oops, thanks.

> I read this and became confused. fixup_message? target_message? Perhaps
> it should be renamed to fixup_commit, squash_commit, target_commit?
>

I was mostly trying to reduce duplicate code for the two cases... but,
I bet when I re-work --squash this will go away.

>> +             struct strbuf buf = STRBUF_INIT;
>> +             struct pretty_print_context ctx = {0};
>> +
>> +             if (get_sha1(target_message, sha1))
>> +                     die("could not lookup commit %s", target_message);
>> +             commit = lookup_commit_reference(sha1);
>> +             if (!commit || parse_commit(commit))
>> +                     die("could not parse commit %s", target_message);
>> +
>> +             format_commit_message(commit, msg_fmt, &buf, &ctx);
>> +             fixup_message_buffer = strbuf_detach(&buf, NULL);
>> +     }
>>
>
> Is it necessary to do this block of code here? Couldn't you lookup and
> format the commit in prepare_to_commit()? Then we wouldn't have to
> allocate another strbuf and the "message" code would be more centralized.
>

Probably not, I was mostly trying to follow the example from the
use_message (-C/-c) feature.  It *would* be nice to avoid the extra
memory (de)alloc.

Thanks for the great feedback!