Re: [PATCH] Use ^=1 to toggle between 0 and 1

["René Scharfe" <l.s.r@web.de>]

Am 12.12.23 um 21:09 schrieb Jeff King:
> On Tue, Dec 12, 2023 at 05:17:47PM +0000, AtariDreams via GitGitGadget wrote:
>
>> diff --git a/diff.c b/diff.c
>> index 2c602df10a3..91842b54753 100644
>> --- a/diff.c
>> +++ b/diff.c
>> @@ -1191,7 +1191,7 @@ static void mark_color_as_moved(struct diff_options *o,
>>  							    &pmb_nr);
>>
>>  			if (contiguous && pmb_nr && moved_symbol == l->s)
>> -				flipped_block = (flipped_block + 1) % 2;
>> +				flipped_block ^= 1;
>>  			else
>>  				flipped_block = 0;
>
> This one I do not see any problem with changing, though I think it is a
> matter of opinion on which is more readable (I actually tend to think of
> "x = 0 - x" as idiomatic for flipping).

Did you mean "x = 1 - x"?

    x 0 - x 1 - x
   -- ----- -----
   -1    +1    +2
    0     0    +1
   +1    -1     0

I don't particular like this; it repeats x and seems error-prone. ;-)

I agree with your assessment of the other three cases in the patch.

Can we salvage something from this bikeshedding exercise?  I wonder if
it's time to use the C99 type _Bool in our code.  It would allow
documenting that only two possible values exist in cases like the one
above.  That would be even more useful for function returns, I assume.

René