completionItem/resolve result may not be null

[bstaletic]

Hello. I'm a maintainer of a LSP client and a user yesterday asked about R support. When tried this server I encountered this:

2021-12-04 09:49:32,608 - DEBUG - TX: Sending message: b'Content-Length: 189\r\n\r\n{"id":2,"jsonrpc":"2.0","method":"textDocument/completion","params":{"position":{"character":18,"line":83},"textDocument":{"uri":"file:///home/bstaletic/work/test/rtest/R/capabilities.R"}}}'
2021-12-04 09:49:32,675 - DEBUG - RX: Received message: b'{"jsonrpc":"2.0","id":2,"result":{"isIncomplete":false,"items":[{"label":"server_capabilities","kind":5,"sortText":"1-server_capabilities","detail":"[scope]","data":{"type":"nonfunction","uri":"file:///home/bstaletic/work/test/rtest/R/capabilities.R","line":79}},{"label":"update_server_capabilities","kind":3,"detail":"[workspace]","sortText":"2-update_server_capabilities","data":{"type":"function","package":"_workspace_"}}]}}'
2021-12-04 09:49:32,676 - DEBUG - TX: Sending message: b'Content-Length: 266\r\n\r\n{"id":3,"jsonrpc":"2.0","method":"completionItem/resolve","params":{"data":{"line":79,"type":"nonfunction","uri":"file:///home/bstaletic/work/test/rtest/R/capabilities.R"},"detail":"[scope]","kind":5,"label":"server_capabilities","sortText":"1-server_capabilities"}}'
2021-12-04 09:49:32,790 - DEBUG - RX: Received message: b'{"jsonrpc":"2.0","id":3,"result":null}'

According to the specification, the response to completionItem/resolve must be a completionItem:

https://microsoft.github.io/language-server-protocol/specification#completionItem_resolve

If the server can't return completionItem, then an error response should be sent.
This is the only thing that stops my client working with R language server.

[renkun-ken]

Please checkout #505 and see if it works for you.

[bstaletic]

Thanks for the quick response. I have checked out the pull request, but I am not sure how to compile or make R look for languageserver::run() in a custom directory. I did try running the tests on the PR's branch.

[renkun-ken]

You just need to install the latest development version of languageserver via

Rscript -e "remotes::install_github('REditorSupport/languageserver')"

[randy3k]

In case you haven't installed remotes.

Rscript -e "install.packages('remotes')"
Rscript -e "remotes::install_github('REditorSupport/languageserver')"

[bstaletic]

Great. Confirming that it works now. Thanks for the quick patch.