View diffs in side-by-side format
Render a unified diff (top/bottom) in an easy-to-comprehend side-by-side format. This comes in handy for reading patches from mailing lists (or from whencever you might acquire them).
M-x package-install diffview
The following functions are provided for launching a side-by-side diff:
diffview-current: View the current diff buffer side-by-side
diffview-region: View the current diff region side-by-side
diffview-message: View the current email message (which presumably contains a patch) side-by-side
Show current diff buffer in a side-by-side view.
Show current diff region in a side-by-side view.
message-mode buffer in a side-by-side view.
This is useful for reading patches from mailing lists.