With `u32` as the element type, rustc 1.93 (with `-O`) does the correct thing for size=1, checks both elements separately (i.e. worse than in the article) for size=2, checks all three elements separately (i.e. not being crazy like in the article) for size=3, and starts doing SIMD at size=4.
This code is not equivalent to the C++ version. You can directly use `*x == [0_u32; SIZE]`. The code generated by the two is different. (But the iterator version not producing optimal code is also an issue.)