Re: [PATCH 4/8] add functions for memory-efficient bitmaps

[Jeff King <peff@peff.net>]

On Sun, Jun 29, 2014 at 03:41:37AM -0400, Eric Sunshine wrote:

> > +static inline void bitset_set(unsigned char *bits, int n)
> > +{
> > +       bits[n / CHAR_BIT] |= 1 << (n % CHAR_BIT);
> > +}
> 
> Is it intentional or an oversight that there is no way to clear a bit
> in the set?

Intentional in the sense that I had no need for it in my series, and I
didn't think about it. I doubt many callers would want it, since commit
traversals tend to propagate bits through the graph, and then clean them
up all at once. And the right way to clean up slabbed data like this is
to just clear the slab.

Of course somebody may use the code for something besides commit
traversals. But I'd rather avoid adding dead code on the off chance that
somebody uses it later (and then gets to find out whether it even works
or not!).

-Peff