如題：

Given your references to Vim in the question, I‘m not sure if this is the answer you want :) but Emacs can do this. 
Open the file containing the diff, make sure that you‘re in diff-mode (if the file is named  foo.diff or foo.patch
 this happens automatically; otherwise type M-x diff-mode RET), go to the hunk you are interested in
 
 and hit C-c C-b
 for refine-hunk. Or step through the file one hunk at a time with M-n; that will do the refining automatically.

https://stackoverflow.com/questions/3231759/how-can-i-visualize-per-character-differences-in-a-unified-diff-file

emacs生疏了，不會用。暫時先不弄了。

[daily] 使用左右對比查看diff 格式的文件