UB from uninitialized values emanates from indeterminate values in C++ and trap representations in C.

C further has unspecified values that become unspecified at a specific point in time but can be copied without mutation of the value. C++ received a National Body comment for C++14 where such cases were removed: https://wg21.link/cwg1787.

It is further an issue that the definition of trap representation does not admit trap representations for the exact-width integer types (int16_t, etc.) because the lack of padding bits, combined with two's complement representation, means that every possible object representation represents a value of the type.

I think it would really help if the C committee could record a decision to move towards harmonizing with C++ on this.

Thanks,

Hubert Tong