Re: [PATCH 08/19] ewah: compressed bitmap implementation

[Jeff King <peff@peff.net>]

On Thu, Oct 24, 2013 at 04:34:48PM -0700, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > From: Vicent Marti <tanoku@gmail.com>
> >
> > EWAH is a word-aligned compressed variant of a bitset (i.e. a data
> > structure that acts as a 0-indexed boolean array for many entries).
> 
> I think I've already pointed out some when the original series was
> posted, but this does not seem to compile with -Wdecl-after-stmt
> (possibly other violations may exist; I haven't looked very closely
> yet).

Sorry about that. I typically compile with "-Wall -Werror" which does
not catch this, and I didn't carefully go over the ewah code for style,
as I considered it mostly a black-box import (though certainly it is
worth fixing this case, as it's not just a style issue).

It looks like there is also some void pointer arithmetic...I _thought_
that was handled by -Wall, but I suppose not. Maybe I need to beef up my
warning settings.

Note that there is also some use of cast-mmap-file-to-struct, only one
instance of which uses __attribute__(packed). However, I notice that the
regular pack code is also guilty of this (e.g., see check_packed_git_idx),
so I don't know how careful we want to be (and whether we should be
using the packed attribute when needed, or if it is sufficiently
non-portable that we want to do it by hand in such cases).

-Peff