In C/C++, are volatile variables guaranteed to have eventually consistent semantics betwen threads?

Question

Is there any guarantee by any commonly followed standard (ISO C or C++, or any of the POSIX/SUS specifications) that a variable (perhaps marked volatile), not guarded by a m

Answer 1

This is a potential data race.

With respect to POSIX thread, this is UB. Same with C++ I believe.

In practice I cannot imagine how it could fail.