Re: [PATCH 1/3] range-diff: refactor check for commit range

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

Phillip Wood <phillip.wood123@gmail.com> writes:

>>   +static int is_range(const char *range)
>> +{
>> +	return !!strstr(range, "..");
>> +}
>
> If the user wrongly passes two arguments referring to single commits
> with `:/<text>` or `@{/<text>}` where text contains ".." this will
> give a false positive.

True.  I do not think this aims to be complete revision parser in
the first place, though.

It is tempting to at least idly speculate if an approach to run
setup_revisions() on argument is_range() takes and checking the
result would yield a more practical solution.  I would imagine that
we would want to see in the resulting revs.pending has at least one
positive and one negative, and none of them have SYMMETRIC_LEFT set
in their .flags word.

    Side note: Strictly speaking, people could wish "rev" to mean
               "everything reachable from the rev, down to root", so
               requiring one negative may technically be a wrong
               thing, but in the context of "range-diff", I am not
               sure how useful such a behaviour would be.