[PATCH 4/5] diff: return line_prefix directly when possible

We may point our output_prefix callback to diff_output_prefix_callback() in any of these cases:

  1. we have a user-provided line_prefix

  2. we have a graph prefix to show

  3. both (1) and (2)

The function combines the available elements into a strbuf and returns its pointer.

In the case that we just have the line_prefix, though, there is no need for the strbuf. We can return the string directly.

This is a minor optimization by itself, but also will allow us to clean up some memory ownership issues on top.

Signed-off-by: Jeff King <peff@peff.net>
---
The old code did handle a case "0" where neither is set. But in that
case we would never set up the callback in the first place. So I didn't
think it was worth being defensive there.

 graph.c | 3 +++
 1 file changed, 3 insertions(+)