Re: [PATCH 2/3] credential: teach `credential_from_url()` a non-strict mode

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 23, 2020, 22:16 UTC
Message-ID: <xmqqtv19etkx.fsf@gitster.c.googlers.com>
In-Reply-To: <xmqqy2qlette.fsf@gitster.c.googlers.com>

Junio C Hamano <gitster@pobox.com> writes:

Show 19 quoted lines

> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>
>> Yes (modulo doing "greater than" comparison on pointers which is IIRC not
>> permitted in C in general).
>
> Of course, people write a loop like this
>
> 	char *cp, *ep = strchr(string, '\n');
>
> 	for (cp = string; cp < ep; cp++)
> 		...
>
> all the time, and forbidding pointer comparison would make the
> language impossible to use ;-)
>
> I think you are confused with a different rule---what is not kosher
> is to compare two pointers that do not point into elements of the
> same array.  Whether the comparison is done in (ptr1 < ptr2) way, or
> (ptr2 - ptr1 < 0) way, does not change the equation.

Having said that, between

1.	if (strict || slash - url > 0)
2.	if (strict || slash > url)
 		c->host = url_decode_mem(host, slash - host);

I think the former is moderately easier to read. It still has the same "Huh?" factor that a comparison between slash and URL guards the size of the region being decoded, which is slash - host, and makes the reader wonder how these two variables, URL and host, relate to each other at this point in the code, though, either way the comparison is spelled.

Thanks.