ns1 = @names c32le { struct X1 { @0x0 int x; @0x4; }; };
ns2 = @names c32le { struct X2 { @0x0 int x; @0x4; }; };

as = mknas();

d1 = mkdom(ns1, as);
d2 = mkdom(ns2, as);

x1 = (struct X1*){d1}0;
x2 = {d2}(char*)x1;  // okay
x2 = {d2}(int)x1;  // okay
x2 = {d2}x1;  // not okay (no struct X1 in d2)