Generate cleaner codes for nil check

[pigpigyyy]

Have been using an idiom to notice user to do a nil check before using some API results.

local record R
   f: function()
end
local function get(): R | nil
end
local r = get()
if not r is nil then
   r.f()
end

And currently r is nil is being generated to (type(r) == "nil"), could make it to be just (r == nil).

[github-actions[bot]]

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[lenscas]

wouldn't this potentially break for tables/userdata that implement their own comparison? As there a == nil can mean something else than type(a) == "nil"

[pigpigyyy]

The __eq metamethod will only be invoked when Lua find both side items from "==" expression to be tables or userdata.

[lenscas]

Ok. Sounds weird but then I guess this indeed doesn't break anything/change behaviour.

[hishamhm]

@pigpigyyy Nice, thank you!