lsp-mode doesn't show textDocument/hover in pop-up when response is MarkedString[]

[niontrix]

Thank you for the bug report

• I am using the latest version of lsp-mode related packages.
• I checked FAQ and Troubleshooting sections
• You may also try reproduce the issue using clean environment using the following command: M-x lsp-start-plain

Bug description

When a language server provides a textDocument/hover response with a single string as content like this:

[Trace - 12:42:18 ] Received response 'textDocument/hover - (15)' in 4ms.
Result: {
  "contents": "File: file:///home/somuser/diy-language-server/README.md, Characters: 302"
}

then the documentation is shown as a pop-up.
When a language server provides a textDocument/hover response with as MarkedString[] like this:

[Trace - 01:04:47 ] Received response 'textDocument/hover - (8)' in 10ms.
Result: {
  "contents": [
    {
      "value": "File: file:///home/someuser/diy-language-server/README.md, Characters: 302",
      "language": "markdown"
    }
  ]
}

then the documentation is shown only in the minibuffer.

Steps to reproduce

• Use for example gopls as a language server and open a Go file. gopls sends its hover responses as single strings.
• Use nimlangserver and open a Nim file. nimlangserver sends its hover responses as an array of MarkedString

Expected behavior

lsp-mode should show hover responses using MarkedString[] as content in a pop-up.

Which Language Server did you use?

I used nimlangserver v1.6.0.

OS

Linux

Error callstack

No response

Anything else?

Also could you please explain how displaying the content of a textDocument/hover response works when being displayed as a pop-up as well as in the minibuffer, so I can get a better understanding of how lsp-mode works and maybe in the future contribute my own PR for issues like this?

[kiennq]

Also could you please explain how displaying the content of a textDocument/hover response works when being displayed as a pop-up as well as in the minibuffer, so I can get a better understanding of how lsp-mode works and maybe in the future contribute my own PR for issues like this?

I don't think lsp-mode has the popup for showing the hover. Are you using lsp-ui for that?
For how the textDocument/hover works in lsp-mode, you can search inside lsp-mode.el, there're 3 places (2 for describe thing at point, 1 for eldoc) that request that, and they will eventually call lsp--render-on-hover-content to display the content.

[niontrix]

Yes, that is how far I understood it, but I couldn't really find how the pop-up is displayed in the end. But I think you're right this might potentially be a problem with lsp-ui. I'll take a look and maybe open a ticket over there.
Thanks! 👍

[niontrix]

I created the following ticket over on lsp-ui - just for reference: #783