gistfile1.lua

function wrap(f)
    return function()
        -- Storing the result of the wrapped function is the source of the
        -- problem.
        result = f()
        return result
    end
end

function f()
    return 1, 2
end

f = wrap(f);
x, y = f()
assert(x == 1 and y == 2)

-- The assertion will fail: x will be 1 and y will be nil. The variable-length
-- return of f() doesn't get passed through the wrapper. When the wrapper says
-- "result = f()", result gets only the first element of the variable return.
-- The rest are silently discarded. See my executable Lua spec for examples
-- that show this in detail:
-- <https://github.com/garybernhardt/LuaSpec/blob/master/spec/function_spec.lua>.