FR: Running jj workspace forget on the main workspace should make another workspace the main one.

[umnikos]

Problem

It is hard to keep track of which workspace is the "main" one (the one with the git store in it). As far as I know there is no command that outputs which workspace is the main one, and jj workspace forget will let you forget the main workspace with no warning. All of this makes it easy to accidentally delete your git store (@chriskrycho can testify to that).

Proposed solution

jj workspace forget-ting the main workspace should first move its git store to another non-forgotten workspace (if there's any) before proceeding with the forgetting. Additionally a command that outputs which workspace is the main one or a command to set which workspace should become the default one would help.

Alternative solutions

The only alternative I can think of is to keep the git directory outside all of the workspaces, but I cannot think of a convenient location.

[arxanas]

What is the current behavior of forgetting the main workspace? It deletes the colocated .git directory (if present), but not the .jj directory? If so, perhaps it should "uncolocate" the Git repository in that case?

[yuja]

What is the current behavior of forgetting the main workspace?

It disassociates the current (or main) working copy from the repo. Nothing should be deleted, but the result would be a bit surprising. We can at least show a warning (with hint to jj undo.)

first move its git store to another non-forgotten workspace (if there's any) before proceeding with the forgetting.

I wouldn't expect the "main" workspace carries to random place by jj workspace forget. I also don't think it's technically possible because there may be other workspaces pointing to the current main repo directory.

fwiw, it might be better to force user to explicitly specify the workspace to forget (with @ or . as a short for the current workspace.)

[arxanas]

All of this makes it easy to accidentally delete your git store (@chriskrycho can testify to that).

@umnikos Can you clarify how it makes it easy to accidentally delete your git store? I didn't follow.

[umnikos]

@umnikos Can you clarify how it makes it easy to accidentally delete your git store? I didn't follow.

@arxanas example:

1. The user has two workspaces, A and B. B is the main one, but the user thinks A is the main one
2. The user wants to bring their setup back down to a single workspace
3. They type jj workspace forget B. The command succeeds
4. They delete workspace B
5. Workspace A is now broken, as it was workspace B that contained the git store

~/Desktop/jj/A $ jj workspace list
A: mpluvnwn de0b4886 (empty) hi
B: qrwusylt b7d95ca3 (empty) hiii
~/Desktop/jj/A $ jj workspace forget B
~/Desktop/jj/A $ jj workspace list
A: mpluvnwn de0b4886 (empty) hi
~/Desktop/jj/A $ rm -r ../B
~/Desktop/jj/A $ jj status
Error: Cannot access /var/home/umnikos/Desktop/jj/B/.jj/repo
Caused by: No such file or directory (os error 2)
~/Desktop/jj/A $ 

[arxanas]

I see, so it doesn't delete the Git store directly, but only enables it in certain workflows. Some other ideas:

• Add or change a command so that it does delete the workspace for you, and then refuse to do so for the main workspace.
  • Presumably in most situations where you want to forget the workspace, you would also want to delete it? It could simplify that workflow incidentally.
  • I suppose we already have a forget/delete distinction for bookmarks, so maybe it's intuitive for some users?
• Show a warning when forgetting the main workspace, as it may be a prelude to disaster.
  • Note that there is probably a legitimate reason to remove the working copy for the main workspace, like if you want to effectively transition to a "bare repo" kind of workflow, but the warning will probably not hurt in that case.

[martinvonz]

Add or change a command so that it does delete the workspace for you, and then refuse to do so for the main workspace.

Makes sense. The main risk I see is that it would delete ignored files (which we don't normally delete).

Show a warning when forgetting the main workspace, as it may be a prelude to disaster.

That's also what Yuya suggested above. I agree with adding it.