That's fair, but I seriously consider the danger of a slippery slope. To keep in mind, on a pragmatic level, that this type of global can be trivially implemen

That's fair, but I seriously consider the danger of a slippery slope. To keep in mind, on a pragmatic level, that this type of global can be trivially implemented, at a minimum, via atomics, so the cost to avoid the unsafe is near-zero. Atomics are not supported by all the platforms, but based on my understanding of their targets (x86-64), they're supported.