[css] API/configuration to extend the CSS language server

[aeschli]

microsoft/vscode-css-languageservice#44 wants to extend the CSS language server with a formatter.

[octref]

@aeschli Would you want to use prettier which has support for css/scss/less for this one? Vetur is using prettier and people like it.

[aeschli]

This is just about adding API so that other products can add it to the language server.
For VSCode this should come from an extension.

[octref]

Do you mean having extension contributing to the css-language-feature extension? I don't feel that complexity is needed. The real blocker is #41882 which doesn't handle multiple formatter as good as we do for completion items / hover. IMO a better solution should be making it possible for multiple registrations of formatters, and making the formatters selectable.

[aeschli]

It's about new language server API. See microsoft/vscode-css-languageservice#44 as the motivation for this request.

[octref]

I don't think this would happen any time soon, or should happen at all.

1. From CSS Format support vscode-css-languageservice#44 it seems @angelozerr still wants CSS LS to bundle a few formatters out-of-the-box, thus all formatter failure blames are on VS Code.
2. Let's say we have such a setting css.formatter where you can choose among an enum. How does it resolve formatting settings? Under some options in css (do we have to add settings for all formatters under css.*?) or if I'm using css.formatter: "prettier", prettier.* options? How can users understand how the settings are applied?
3. We don't easily bundle external features/dependencies into VS Code, if the functionality is easily implementable by an extension. In this case, you can write another Language Server for CSS just for formatting.

[vscodebot]

We closed this issue because we don't plan to address it in the foreseeable future. You can find more detailed information about our decision-making process here. If you disagree and feel that this issue is crucial: We are happy to listen and to reconsider.

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