[akavel]

Ah, now I get your question. So, it is a function declaration, not a function call. Um, sorry: a declaration of a pointer to a function, where this function would take as arguments: some (unnamed) void pointer, some (unnamed) int value, and some (unnamed) size_t value; and would return a void pointer.

Um; then there's the equal sign, so this is not only a declaration, but a definition too; but definitely not a call.

A call is further down in the original blogpost, in the below line:

    (memset_ptr)(p, 0, len);

[StavrosK]

Oh! A pointer to a function! Aha, I didn't know that was valid, thanks!