Add support for the "textDocument/formatting" verb

[vonlost]

Sorry if this request is covered elsewhere.

[ahoppen]

I don’t think we’ve got a bug report for this. It’s very related to #496.

[ahoppen]

rdar://96159694

[fwcd]

I think the DocumentFormattingRequest represents this LSP method, there is some ongoing work at #361 to implement this via swift-format.

[siegel]

@fwcd which version of Xcode does this correspond to?

As of Xcode 13.4 (13F17a), sourcekit-lsp is not advertising support for textDocument/formatting in its capabilities:

{
    codeActionProvider =     {
    };
    colorProvider = 1;
    completionProvider =     {
        resolveProvider = 0;
        triggerCharacters =         (
            "."
        );
    };
    definitionProvider = 1;
    documentHighlightProvider = 1;
    documentSymbolProvider = 1;
    executeCommandProvider =     {
        commands =         (
            "semantic.refactor.command"
        );
    };
    foldingRangeProvider = 1;
    hoverProvider = 1;
    implementationProvider = 1;
    referencesProvider = 1;
    textDocumentSync =     {
        change = 2;
        openClose = 1;
        save =         {
            includeText = 0;
        };
        willSave = 1;
        willSaveWaitUntil = 0;
    };
    workspaceSymbolProvider = 1;
}

[fwcd]

Yes, IIUC the provider is not registered since the request is yet to be implemented (WIP at #361), only the request structures have been merged already.

[t-benze]

For anyone having the problem that sourcekit is not able to perform the code format action. If you happen to use neovim, there's one working solution (as a workaround) using this null-ls plugin.

There're a few steps to set up:

1. follow the instruction to install swift-format.
2. make sure the swift-format executable is locatable from $PATH.
3. install the null-ls neovim plugin and configure swift-format, for example

local null_ls = require("null-ls")
local swift_format = require("null-ls.builtins.formatting.swift-format")
null_ls.register({swift_format})