Re: [PATCH v4 2/3] add-patch: classify '@' as a synonym for 'HEAD'

> Ghanshyam Thakkar <shyamthakkar001@gmail.com> writes:
> 
>> Currently, (checkout, reset, restore) commands correctly take '@' as a
>> synonym for 'HEAD'. However, in patch mode (-p/--patch), for both '@'
>> and 'HEAD', different prompts/messages are given by the commands
>> mentioned above (because of applying reverse mode(-R) in case of '@').
>> This is due to the literal and only string comparison with the word
>> 'HEAD' in run_add_p(). Synonymity between '@' and 'HEAD' is obviously
>> desired, especially since '@' already resolves to 'HEAD'.
>>
>> Therefore, replace '@' to 'HEAD' at the beginning of
>> add-patch.c:run_add_p().
> 
> Of course there is only one possible downside for this approach, in
> that if we are using "revision" in an error message, users who asked
> for "@" may complain when an error message says "HEAD" in it.  I think
> the simplicity of the implementation far outweighs this downside.

>> There is also logic in builtin/checkout.c to
>> convert all command line input rev to the raw object name for underlying
>> machinery (e.g., diff-index) that does not recognize the <a>...<b>
>> notation, but we'd need to leave 'HEAD' intact. Now we need to teach
>> that '@' is a synonym to 'HEAD' to that code and leave '@' intact, too.
> 
> Makes me wonder why we cannot use the same "normalize @ to HEAD
> upfront" approach here, though?
> 
> It would involve translating "@" given to new_branch_info->name to
> "HEAD" early, possibly in setup_new_branch_info_and_source_tree(),
> and that probably will fix the other strcmp() with "HEAD" that
> appears in builtin/checkout.c:update_refs_for_switch() as well, no?
> 
>> +	/* helpful in deciding the patch mode ahead */
>> +	if(revision && !strcmp(revision, "@"))
>> +		revision = "HEAD";
> 
> Style.  "if (revision ...)"
>