Well, just before I just saw a "read" and a "write" to address 0. Not as mechanism that can cause serious bugs, when the compiler can statically prove length a

Well, just before I just saw a "read" and a "write" to address 0. Not as mechanism that can cause serious bugs, when the compiler can statically prove length argument to be 0 and you can have NULL arguments as input. Calls to memcpy with zero length are definitely not uncommon. Macros are an obvious way, but it's worse. All you need is a data flow where compiler can statically prove that all paths lead to zero length argument. I have to agree it's very scary that memcpy(NULL, NULL, 0) is undefined.