Support function arguments in completion snippets

[andersevenrud]

I came across #15 while doing some research , and this was closed with a recommendation to OP to make a new issue when it came to snippet support (i.e function parentheses and function arguments / signature) on completion, but never did.

So I thought I'd open one as I would love to see support for this feature.

[hungrybirder]

I really want this feature.

[rchl]

I've investigated how https://github.com/neoclide/coc-tsserver (which is a fork of vscode's TS language features) handles that and it appears that there is quite a bit of custom code to support that (through optional setting).

[rchl]

For the record, vscode implements this through an optional javascript.suggest.completeFunctionCalls / typescript.suggest.completeFunctionCalls setting. This likely has an issue with signature help not being triggered when using it so that's probably why it is disabled by default.

[sf8193]

is there anything i need to do to enable this? doesn't seem to be working for me @rchl

[rchl]

There is a setting for it that is by default disabled:

typescript-language-server/README.md

Lines 303 to 312 in c07426a

	/**
	* Complete functions with their parameter signature.
	*
	* This functionality relies on LSP client resolving the completion using the `completionItem/resolve` call. If the
	* client can't do that before inserting the completion then it's not safe to enable it as it will result in some
	* completions having a snippet type without actually being snippets, which can then cause problems when inserting them.
	*
	* @default false
	*/
	completions.completeFunctionCalls: boolean;