All of them will under circumstances that tend to manifest when wiping secrets. This surprises a lot of developers, but it's a very common finding when auditing crypto code or other secret storage.
It's typically done when you don't need the value anymore, of course. So, the compiler sees a write to memory that is never used. Which is exactly the type of thing compilers try to optimize out (if it can be proven that it is never used).
From the C99 standard:
In the abstract machine, all expressions are evaluated as specified by the semantics. An actual implementation need not evaluate part of an expression if it can deduce that its value is not used and that no needed side effects are produced (including any caused by calling a function or accessing a volatile object).
It's typically done when you don't need the value anymore, of course. So, the compiler sees a write to memory that is never used. Which is exactly the type of thing compilers try to optimize out (if it can be proven that it is never used).
From the C99 standard:
In the abstract machine, all expressions are evaluated as specified by the semantics. An actual implementation need not evaluate part of an expression if it can deduce that its value is not used and that no needed side effects are produced (including any caused by calling a function or accessing a volatile object).