Support for a bottom type for non-returning functions

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Windows

What is the issue affecting?

Type Checking

Expected Behaviour

Have a way to tag the return type of a function as Bottom, i.e., never returns.

Actual Behaviour

I have a snippet like this:

local function abort(err)
	io.stderr:write(err .. "\n")
	os.exit(1)
end

local function stuff()
	local chunk = loadfile("x.lua")
	if not chunk then
		abort("failed to loadfile()")
	end
	chunk()
	return {}
end

stuff()

which triggers the "need-nil-check" diagnostic on "chunk()" because it doesn't understand that abort() never returns, so i would like to tag abort() (or better tag os.exit() and do return os.exit) as never returning function.

obvious work-around is to do "return abort(...)" instead, but that messes up the return type of stuff() from table to table|nil. so i have to write abort() return {} to make the type checker happy which is a bit cumbersome

Reproduction steps

1. Go to '...'
2. Click '...'
3. See error '...'

Additional Notes

No response

Log File

No response

Comece pelo caminho de verificação de tipos para o diagnóstico need-nil-check e pelas anotações existentes de tipo de retorno das funções. Compare o tratamento solicitado de abort e os.exit com a forma como o checker infere stuff() após a chamada. Considera-se concluído quando uma função que não retorna pode ser representada de modo que o diagnóstico nil seja evitado sem adicionar nil ao tipo de retorno de stuff().