Re: [PATCH 2/2] pickaxe: use textconv for -S counting

[Junio C Hamano <gitster@pobox.com>]

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

>> Exact renames are the obvious one, but they are not handled here.
>
> That is half true.  Before this change, we will find the same number
> of needles and this function would have said "no differences" in a
> very inefficient way.  After this change, we may apply different
> textconv filters and this function will say "there is a difference",
> even though we wouldn't see such a difference at the content level
> if there wasn't any rename.

... but I think that is a good thing anyway.

If you renamed foo.c to foo.cc with different conversions from C
code to the text that explain what the code does, if we special case
only the exact rename case but let pickaxe examine the converted
result in a case where blobs are modified only by one byte, we would
get drastically different results between the two cases.

Corollary to this is what should happen when you update the attributes
between two trees so that textconv for a path that did not change
between preimage and postimage are different.  Ideally, we should
notice that the two converted result are different, perhaps, but I
do not like the performance implications very much.