Are nested table lookups in the same function optimized?

[JDaance]

Will chains like this be optimized in luau somehow?

function update(state)
	if state.player.name.display then
		if state.player.name.display.color then
			setColor(state.player.name.display.color)
		end
	end
end

In normal "naive" lua I would try to optimize like this

function update(state)
	local display = state.player.name.display
	if display then
		local color = display.color
		if color then
			setColor(color)
		end
	end
end

I wonder how necessary this kind of manual optimization is in Luau?

This example might be a bit exaggerated, but I see this pattern in my code all the time. It would be very nice if the style of code chosen here is more of an aesthetic preference instead of trying to help lua with table access.

[Dionysusnu]

Because of metatables, optimising this would be unsound. If the __index is a function, it could set a variable to make it return something different the next time.
Eg the first state.player may give something different to the second state.player.
It's theoretical, but it is possible.

[JDaance]

I get what you're saying as such, which is obviously correct and somewhat unfortunate for my needs in this case. But are you saying that you know for a fact that Luau does nothing to optimize this case?

[zeux]

We currently don't optimize this pattern, so indeed using locals to cache the intermediate lookups can be beneficial for performance. We do plan to look into optimizing cases like this because they are surprisingly prevalent; doing this is likely going to require some subtle changes to the semantics of the language, so it's not something we can do quickly or easily as we'd need to evaluate the impact on compatibility.