Cute! However, if you really want complete equivalence between locals and struct* parameters, you might prefer something like "struct { int n; } _z, * const z

Cute! However, if you really want complete equivalence between locals and struct* parameters, you might prefer something like "struct { int n; } _z, * const z = &_z;". There's a slight difference of types when using your array version, so things like sizeof(z) and &z don't mean the same thing as when used on struct* parameter.