[gpderetta]

Everything defined in the standard is in principle a language construct: whether it is builtin in the compiler or an actual function is an implementation detail. For many compilers, memcpy is both: they have builtin handling for it but fall back to the library implementation when there is no optimization opportunities.

Having said that, it is possible to implement memcopy in standard C: char pointers have an explicit special exemption to the aliasing rule so you are allowed to inspect objects as array of chars.