Understanding Structural Equivalence

Question

I have two types of structural equivalence ideas I am struggling to understand.

VAR_1 = int
VAR_2 = pointer to VAR_1

So here, I feel like they

Answer 1

This depends entirely on how the concepts of pointer and int are implemented, as well as what structural equivalence means in your particular scenario.

Structural typing is concerned with whether one thing has the same structure as another thing, which means the implementation of the individual structures matters a great deal.

Here is a quick pseudocode definition for both types.

int definition
    32 bit value

pointer definition
    32 bit value

Two different types, but they contain the exact same members, even though semantically they are treated differently (the pointer is assumed to hold a memory address). These are structurally equivalent.

Here's another implementation.

int definition
    32 bit value

pointer definition
    64 bit value

Those aren't structurally equivalent, even though they both have a member called 'value'. How about this?

int definition
    value
    other value

pointer definition
    other value
    value

These might not be considered the same because the members are in a different order, although they are named/typed the same.

My point is that this is entirely up to the implementors of whatever language or environment this is a part of and what things mean in that world.