On Friday, October 24, 2025, Sebastian Wittmeier wrote:
You don't know the reason the object is unmovable.
The address space of the object may be mapped to the hardware.
Copying and restoring may lead to errors.
Simple example: A DMA buffer.
You could get this on a microcontroller too, where addresses above 0x2000 are volatile memory, and addresses from 0x0 to 0x800 are the input for a digital-to-analog converter.
And so if the 'replace' template function were to be added to the C++ Standard library, then some classes would need to be given a tag to indicate that you can't put them into temporary cryostasis, something like:
namespace std {
class mutex {
public:
typedef int no_cryostasis;
};
}