copying const

[Freddy via Digitalmars-d]

I was surprised when this happened, is it a bug or a feature?

---
struct A
{
     const int var;
}

int test()
{
     auto b = A(5);
     auto c = A(7);
     pragma(msg, typeof(b)); //A
     pragma(msg, typeof(c)); //A
     auto d = b; //compiles
     b = c; //doesn't compile
}
---
$ rdmd -main -unittest test
A
A
test.d(13): Error: cannot modify struct b A with immutable members
Failed: ["dmd", "-main", "-unittest", "-v", "-o-", "test.d", 
"-I."]