vim-slime fails to send text when Neovim's vim.opt.shell is set to "pwsh.exe"

[lksherpa]

When configuring Neovim, setting vim.opt.shell = "pwsh.exe" breaks vim-slime functionality. Both :SlimeSendCurrentLine and <C-c> <C-c> run without errors but send no text to the target pane. This occurs with multiple targets (such as tmux and wezterm). The issue disappears as soon as the shell option is removed or changed to "cmd.exe".

I understand the basic differences between PowerShell and CMD, but I didn’t expect them to affect how vim-slime communicates with other panes. I’m sharing this in case it helps someone else avoid the same confusion. This seems more like a user error than a problem with vim-slime.

I have no clue what you take into account when writing the README but If anything, it might be helpful for it to mention that some shells—like PowerShell—can interfere with text transmission, as this was not obvious (for me at least) at first.

I can provide extensive information about my config but given the nature of this issue I did not deem it relevant to do so initially.

Have a lovely day :)

[jpalardy]

Hi @lksherpa

Thanks for reporting this!

I don't run on Windows myself so I don't have deep insights… If you'd like to take a stab at the README, open a PR and we can iterate.

Thanks

[lksherpa]

Hey @jpalardy

I would only feel comfortable "taking a stab" at it if I'm confident I understand the actual issue so maybe I will do a bit of research first and report back in the form of a PR.

In the meantime, I'll let you handle this "issue's closing" as I have no clue if I'm supposed to leave it open or not.

Thanks for the prompt answer. I hope the rest of your 2025 goes smoothly !

[jpalardy]

Let's leave the issue open for now, you can report your findings here 👍

[lksherpa]

It’s a straightforward parsing issue related to how PowerShell expects arguments to be quoted.

Here's an example from a WezTerm window, without involving Neovim’s system() function or its shell-related options (vim.o.shell, vim.o.cmdflag, vim.o.shellquote, vim.o.shellxquote).

In the first case, the argument is wrapped in a single ", and PowerShell fails to parse it.
Outcome: the text is not sent.

In the second case, the argument is wrapped using "", which PowerShell parses correctly.
Outcome: the text is sent.

When using PowerShell as vim.o.shell inside Neovim, the parsing behavior is controlled mainly by:

vim.o.cmdflag = "-Command"
vim.o.shellquote = ""
vim.o.shellxquote = ""

For most use cases involving :! or system(), I believe this is a good base config.
It’s not entirely clear to me why an empty vim.o.shellquote results in correct parsing, but it does (when vim.o.shell is set to pwsh.exe).
I think my confusion stems from: applying the same exact logic (no shellquote wrapping) outside nvim makes very little sens.

pwsh.exe -Command wezterm cli send-text "double quote" --pane-id=1

Above is how I assume the structure of the nvim shell call looks like.

I think I can live with that for now. Especially as I'm not planning on using pwsh as my shell anymore.

Additional clarification:
In my initial message I mentioned that the issue affected multiple targets, such as WezTerm and tmux. That was inaccurate. When testing under WSL, what failed was not really vim-slime but simply that the shell set for nvim in wsl (pwsh.exe) was inaccessible ([interop] related in wsl.conf).

I had copied my config and forgot about it.

I think that explains that.

I do not really think it is vim-slime's README's job to educate people about how pwsh parsing works, that being said I dont exactly think it would hurt to add a one liner for pwsh user as a reminder.

What do you think ?

[jpalardy]

Hi @lksherpa

Good summary 👍

The real question is where to put this info so people can find it 🤔

Maybe here?

With a blurb "if you're using Windows, read this first" and a link to a Windows-specific sub-README?

[lksherpa]

Sounds good !

[lksherpa]

[I'm still talking about what happens when vim.o.shell is set to pwsh.exe]

Just want to add that even though, the quoting related vim.o's do allow the system calls to work as intended I am experiencing an added delay which I'm not when using cmd.exe.

(With those vim.o's) Calling the string arg variant of system(), like slime does in slime#common#system results in a delay. Using the list arg variant of system() works without any issues regardless of shell related vim.o's (as is expected I believe).

So really my recommendation would just be for windows users to use cmd.exe as their vim.o.shell.

:Sendwithsysraw causes the same delay I'm seeing when using the same vim.o's (note that similarly to vim-slime it also simply just does not work if the vim.o's parsing related options are different than those discussed above).

:Sendwithsyslist works just fine.

I'm aware that slime's design choice is to use system(string) and I'm sure that there's many good reasons to do so.

I'm confident that an "elegant" fix should not be all that hard to find but for now as I already said I'm really okay with it as it is.

I have not tried to replicate this in a clean way yet (so with a bit of hope I'm just yapping away since the beginning and this will never affect any other pwsh users). I might do that some day and come back to this issue with an actual fix.

In the meantime I can't really offer pwsh users any definite answer.
So if we do add something to the README, I would feel more comfortable if it was just a warning and a link to a summary of my experiences rather than an actual complete explanation and "fix". In hopes that it takes said users less time to figure it out if they experience similar issues.

Have a lovely evening :)