Can we remove undefined features? We can get rid of the GCC optimizations which rely on the premise of undefined behavior to break code to win a speed prize or something, but undefined behavior exists for a reason:
It depends on the CPU.
The problem is that C was designed to be as close as possible to hardware, and some places (RTOS? Kernel?) speed is critical.
It depends on the CPU.
The problem is that C was designed to be as close as possible to hardware, and some places (RTOS? Kernel?) speed is critical.