How to UNDO dp (or :diffput) in vimdiff, "u" doesn't work-CodePudding

I have started using vimdiff as my git difftool, and I have accidentally used the command dp (diff put) to put some code to the other file. However, pressing u does not undo that, and vim says at the bottom "Already at oldest change"

Undoing do (diff obtain) command works perfectly, but strangely not with dp !!

Any ideas?

CodePudding user response：

a is the current buffer:

 -------- -------- 
| 1      | 2      |
|        |        |
|        |        |
|        |        |
 -[a]---- --b-----

b is the target of dp so, after dp, the current buffer is unchanged and u is useless. It is the target that is changed and you can't undo a change in one buffer from another one:

 -------- -------- 
| 1      | 1      |
|     == dp =>    |
|        |        |
|        |        |
 -[a]---- --b*----

b must become current for u to work:

 -------- -------- 
| 1      | 1      |
|        |        |
|        |        |
|        |        |
 --a----- -[b]*---  do <C-w>w to change window

after u:

 -------- -------- 
| 1      | 2      |
|        |        |
|        |        |
|        |        |
 --a----- -[b]----

Now, let's go back to the beginning, with a being current:

 -------- -------- 
| 1      | 2      |
|        |        |
|        |        |
|        |        |
 -[a]---- --b-----

After do, it is the current buffer that is changed:

 -------- -------- 
| 2      | 1      |
|     <= do ==    |
|        |        |
|        |        |
 -[a]*--- --b-----

and the change can be undone with u without having to change windows:

 -------- -------- 
| 1      | 2      |
|        |        |
|        |        |
|        |        |
 -[a]---- --b-----