x/tools/gopls: add missing comma before newline in composite literal

[drice]

Whenever it is detected that a comma is missing before a newline in a composite literal, is it possible to add it?

Past issues for vscode-go:

• Feature request: Add "," after inserting "}" microsoft/vscode-go#738
• Adding a comma into composite literals microsoft/vscode-go#818

[k-jingyang]

Hello, I'd like this feature as well. If external contributors can work on this feature, let me give it a try. 😄

[k-jingyang]

After digging a little, it seems that the double quotes are coming from vscode's go language configuration.

https://github.com/microsoft/vscode/blob/main/extensions/go/language-configuration.json

If we use the complete from the LSP, the comma is generated (though the double quotes are not generated in this case)

If we don't use complete, the comma will not be generated

I'm new to the LSP spec. Seems like it does not support auto-filling characters without having a completion prompt. So, if we want to improve user experience, we could get the completion (textDocument/completion) to insert double quotes if the struct field is a string?

[findleyr]

As @k-jingyang points out, the comma is populated by auto-completion.

Within the constraints of LSP we don't have the ability to always automatically add the comma, but we can add a quick-fix to do so. @drice would that be sufficient?

[drice]

@findleyr Yes, that would be sufficient