Re: [PATCH] Built-in diff driver shows Index: line.

LT> Actually, I do dislike the Index: line, and think this is a pretty LT> intrusive work-around for a problem with diffstat.

Alright.  Please consider the patch retracted.

LT> Oh, actually maybe the better pattern to use is the one that GNU diff LT> itself ends up matching: LT> "*** %[^\t ]%[\t ]%d%c%d%c%d %d:%d:%d" LT> where the "%c" has to be either '-' or '/' (ie it ends up matching as LT> "numeric date" + "numeric time").

LT> You can put the "mode" thing at the end, and diffstat won't care about it.

Hmph. Timestamps do not mean anything in most of the intended use of diff-* family, since they are meant to operate on trees, except:

 - comparing against the working tree --- show-diff's <new> and
   diff-cache's <new>; we can take the timestamp from the
   filesystem.

 - comparing against a tree that comes from a known commit ---
   we can take the timestamp of the commit that contains the
   file.

If we want to show the timestamp of the latter, diff-tree and diff-cache need to be taught to take notice if their tree-or-commit parameter is actually a commit and if so needs to pass the timestamp in the committer field down the path for the diff driver. There is no way for diff-tree-helper to do this because the origin information is already stripped out when it sees a valid SHA1.

So I'd say we'd punt this one for now, unless somebody else has a better idea.