Re: [PATCH] Add -O<orderfile> option to diff-* brothers.

LT> This smells to me like a "cool feature, because we can" LT> rather than a "this is useful because of xxx".

You could even do the rename/copy detection outside with a standalone diff-raw filter, just like your "sort-filenames" pipe example. Rename/copy is not done that way primarily for the performance reasons. Pickaxe is not done that way because we wanted to conditionally suppress diff-tree headers, and it is easier to implement the suppression inside rather than as a "sort-filename" like filter.

This diffcore-order is more like "cool feature, because we can, _and_ it is simpler to do it inside rather than outside, now we already have the infrastructure inside to do this kind of thing for other purposes anyway".