Re: [PATCH 2/5] xdiff: replace mmbuffer_t with mmfile_t

> Our import of xdiff has two identical buffer structures: mmfile_t and
> mmbuffer_t. In upstream xdiff these were actually different, but the
> import in 3443546f6e (Use a *real* built-in diff generator, 2006-03-24)
> simplified mmfile_t to a simple buffer.
>
> In xdiff we usually use mmfile_t for input and mmbuffer_t for output,
> but they are really both just a ptr/len pair. I don't think that having
> different types is buying us anything in terms of type safety or
> semantics, and having two makes it awkward to use the same helpers for
> both. In particular, an external merge driver's output is read from a
> file, but we can't easily use read_mmfile(), since we want the result in
> an mmbuffer_t.
>
> Let's use mmfile_t for both cases and drop mmbuffer_t. The latter is
> probably a more descriptive name, but we have many more uses of
> mmfile_t (and helpers like read_mmfile). So let's consolidate using that
> name; we can always change it to something more sensible later.
>
> There should be no behavior change here; this is just consolidating the
> types.

>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> I guess this step might be controversial, but I hope not. I think the
> ship has long sailed on trying to pull "upstream" changes from xdiff
> (there haven't been any, and we've hacked it up quite a bit already).