[arielby]

A pointer points to the start of its pointee - i.e. the point "just before" its pointee. That's how derived-to-base casts work. That's also how you can have "one-past-the-end" pointers, which are actually "just after" the relevant array.

for example, if you have the following structs

    typedef struct { void *key; } base;
    typedef struct { base b; int misc; int data[2]; } derived;

then derived is laid out as follows

    -----+------+---------+---------+---------+-----
     ... | base | derived | data[0] | data[1] | ...
    -----+------+---------+---------+---------+-----
         ^                ^                   ^
         |                |                   |
        base         derived.data      &derived.data[2]

[matchu]

Yep. A pointer is a memory range, but it supports a cast operation that allows you to change the pointer type, and therefore the end address. I think we agree, right? :)

[arielby]

Except you can have a void* that does not have an end address.

[matchu]

Hmm, yeah, void pointers are weird. I'd be inclined to say that its start and end address are the same and it's a range over 0 bytes of memory, and the fact that dereferencing fails is an artifact of the dereferencing operation itself... but I don't know enough about void pointer voodoo to know whether that's actually a consistent interpretation.