util.smqueue: Refactor checkpoint logic and add tests The previous checkpoint logic used recursion, and the code was more complex than needed due to maintenance of the self._next_checkpoint field. This switches to a loop, which should be a bit more efficient, partly because there are fewer calls (although it was a tail call) and because table lookups can now be cached between each execution. _call_checkpoints() is now called unconditionally for every ack, which is simpler though adds a function call, it should be more than balanced out by the other changes.

-- Compatibility layer for bitwise operations

-- First try the bit32 lib
-- Lua 5.3 has it with compat enabled
-- Lua 5.2 has it by default
if rawget(_G, "bit32") then
	return _G.bit32;
end

do
	-- Lua 5.3 and 5.4 would be able to use native infix operators
	local ok, bitop = pcall(require, "prosody.util.bit53")
	if ok then
		return bitop;
	end
end

error "No bit module found. See https://prosody.im/doc/depends#bitop";