Error NO_RESULT_CALLBACK_FOUND with Neovim's native LSP

[dtomvan]

rust-analyzer version: rust-analyzer ad6810e 2022-06-06 stable

rustc version: rustc 1.62.0-nightly (f4a7ce997 2022-04-08)

neovim version: NVIM v0.8.0-dev 37ee800b519

relevant settings:

CARGO_HOME=/home/tomvd/.local/share/cargo
RUSTUP_HOME=/home/tomvd/.local/share/rustup

Neovim LSP config is done with https://github.com/simrat39/rust-tools.nvim and https://github.com/williamboman/nvim-lsp-installer

Link to (very long) log: https://www.toptal.com/developers/hastebin/ihiguxinej.properties

Ref: neovim/neovim#15844
The above issue told me that the issue is with the language server, not with neovim itself.

[ten3roberts]

This issue is reprocucible with the default

require"lspconfig".rust_analyzer.setup {}

[flodiebold]

neovim/nvim-lspconfig#225 says the configs there are "best-effort" and unsupported. I don't see anything saying that it's a server issue. The log seems to just be a completion response. If there are some specific steps that lead to the error, it would help if you could name them, and see whether they lead to similar errors with other clients (VSCode, Emacs, ...). If the issue does not happen with older rust-analyzer versions, that would also be interesting. Otherwise I would suggest asking at nvim-lspconfig or rust-tools.nvim.

[dtomvan]

neovim/nvim-lspconfig#225 says the configs there are "best-effort" and unsupported. I don't see anything saying that it's a server issue. The log seems to just be a completion response. If there are some specific steps that lead to the error, it would help if you could name them, and see whether they lead to similar errors with other clients (VSCode, Emacs, ...). If the issue does not happen with older rust-analyzer versions, that would also be interesting. Otherwise I would suggest asking at nvim-lspconfig or rust-tools.nvim.

This error just occurs when typing things (at random moments). I have no idea where the issue may be coming from. I'll try without rust-tools.nvim, and on Emacs, to see if it is any issue with rust-analyzer, or with the Neovim LSP config.

I think the issue started coming up when upgrading from rust-analyzer 2022-06-06 (system installation on Arch Linux) to the one used by nvim-lsp-installer, which is the version in my previous comment.

Edit: I won't need to check if it works without rust-tools, as that has been checked by ten3roberts.

[dtomvan]

Update: This doesn't occur on Emacs, so I think this issue is nvim-lspconfig specific. Using the normal (non-lsp-installer) version of rust-analyzer doesn't help. I did update from lspconfig version 84252b0 to eb03999, but downgrading back doesn't help either. I guess this issue just started appearing all of a sudden, which I find weird.

[dtomvan]

Another update: (I'm sorry for the spam) The latest version (package in Arch Linux's community repo) I can find not to error is rust-analyzer 2022-05-30. I guess it is some breaking change in rust-analyzer, then.

[ten3roberts]

I downgraded from the 2022-06-06 to 2022-05-30 and everything works perfectly.

[Kangaxx-0]

Same issue after upgrading rust_analyzer with version 2022-06-06

[flodiebold]

If someone could bisect the issue to a specific commit in that range, that would be helpful.

[jonhoo]

@flodiebold I'll give that a shot — stay tuned!

[jonhoo]

e2da967 is the first bad commit, so #12431 (cc @Veykril)

Here's one particularly short error I get a fair amount, if it helps:

LSP[rust_analyzer]: Error NO_RESULT_CALLBACK_FOUND: {
  id = 19,
  jsonrpc = "2.0",
  result = {
    isIncomplete = true,
    items = {}
  }

[Veykril]

Hmm, I can only make an assumption here but I imagine that nvim discards requests of a certain kind it sent out if a newer one has been answered. That is if we have requests like completion:id the following might now be happening:

nvim request completion:0
r-a starts processing
nvim request completion:1
r-a cancels completion:0 and requeues it, starts processing completion:1
r-a response completion:1
nvim acknowledges, discards all completion callbacks for ids <= 1
r-a response completion:0
nvim can't find a completion callback for id 0 and errors

This is might seem odd for r-a to do, but to my knowledge the LSP permits this kind of processing. it specifically states that each request has to be replied to, but not in what order.

Though again, this is a wild guess, I do not know how nvim's lsp implementation works, but if this is the case I would argue that this is an implementation error on nvim's side (even if we try to fix the ordering here).

[jonhoo]

@justinmk would love your input here in trying to figure out if this is a rust-analyzer LSP bug, or a bug/missing feature on the neovim LSP side of things. Does what Veykril outlined above match the actual behavior of neovim?

[toothlesslizard]

:LspInstall rust_analyzer@2022-05-30

but i ve got RPC Error sometimes, only RUST related.

[justinmk]

This is might seem odd for r-a to do, but to my knowledge the LSP permits this kind of processing. it specifically states that each request has to be replied to, but not in what order.

@Veykril thanks for that analysis. If someone can open a new Nvim issue I have reopened neovim/neovim#15844

Related Nvim LSP client code: https://github.com/neovim/neovim/blob/4d9e2247c939a5df0a79a06f37ab882ff66aeb01/runtime/lua/vim/lsp/rpc.lua#L554

How do other LSP clients handle this? Just ignore it?

neovim/nvim-lspconfig#225 says the configs there are "best-effort" and unsupported

nvim-lspconfig is just configs, it is not the Nvim LSP client.