Re: [PATCH 1/4] ref-filter: factor out refname component counting

> On Tue, Feb 17, 2026 at 10:07:29AM -0800, Junio C Hamano wrote:
>
>> Jeff King <peff@peff.net> writes:
>>
>> > +	if (len < 0) {
>> > +		int i;
>> > +		const char *p = refname;
>> > +
>> > +		/* Find total no of '/' separated path-components */
>> > +		for (i = 0; p[i]; p[i] == '/' ? i++ : *p++)
>> > +			;
>>
>> Sorry, but I have no idea what this loop (copied verbatim from the
>> original) is trying to do.
>>
>> We start at the beginning of the refname string, and while we are in
>> the leading run of '/' we increment i to find the end of that
>> run. E.g., we start with refname="///foo", p points at the leftmost
>> '/', i runs from 0 to 3 at which point p[i] points at the first
>> non-'/' character, at which point we do *p++, to make p point at the
>> second slash?  Is the dereferencing of the pointer in *p++ a no-op
>> that is there only to confuse readers?
>>
>> And then p moves to the right until p[i] points at the end of the
>> string.  It does count the number of slashes in 'i', but there is no
>> satisfying simple answer to this question: "what does p mean while
>> this loop runs?".
>>
>> Anyway, the conversion looks very faithful to the original.
>
> Heh, I missed your message initially but was independently staring at
> this because Coverity complained that the dereference in "*p++" is
> useless. Which is...kind of right. It is a void context, so the
> dereferenced char goes nowhere and it is a noop. But if you don't do it,
> then gcc complains that the two sides of the ternary have mis-matched
> types (an int and a pointer). Which is true, but since nobody looks at
> the result, it does not matter.
>
> Writing it like:
>
>   int i = 0;
>   while (p[i]) {
> 	if (p[i] == '/')
> 		i++;
> 	else
> 		p++;
>   }
>
> perhaps resolves the syntactic confusion. Leaving only the semantic
> confusion. ;)
>
> I guess the thinking was that "p+i" represents the traversal, with "i"
> encoding the counted slashes (so we must increment _one_ of them each
> time). But I cannot fathom how that is easier than counting the slashes
> like:
>
>   int slashes = 0;
>   for (p = refname; *p; p++) {
> 	if (*p == '/')
> 		slashes++;
>   }
>
> Which made me wonder if I am missing some corner case, and it is not
> just counting slashes. But it must be, because "i" is never incremented
> except when we see a slash.
>
> +cc Karthik, the original author, for any wisdom, but the commit is now
> almost 10 years old.
>

> Is it worth rewriting to the "slashes" form above for clarity? I was
> afraid to touch it just to shut up Coverity, but now we have two
> confused people.
>
> -Peff