Another shot at fixing the issues with (constant) struct literals and their addresses. See DMD2682, #218, #324. The idea is to separate the notion of const from 'this variable can always be replaced with its initializer' in the frontend. To do that, I introduced Declaration::isSameAsInitializer, which is overridden in VarDeclaration to return false for constants that have a struct literal initializer. So {{{ const S s = S(5); void foo() { auto ps = &s; } // is no longer replaced by void foo() { auto ps = &(S(5)); } }}} To make taking the address of a struct constant with a struct-initializer outside of function scope possible, I made sure that AddrExp::optimize doesn't try to run the argument's optimization with WANTinterpret - that'd again replace the constant with a struct literal temporary.

module bug9;
extern(C) int printf(char*, ...);

struct rgb
{
  ubyte[3] values;
  rgb average(rgb other)
  {
    rgb res;
    foreach (id, ref v; res.values) v=(values[id]+other.values[id])/2;
    return res;
  }
  void print()
  {
    printf("[%d,%d,%d]\n", values[0], values[1], values[2]);
  }
}

void main()
{
    rgb a,b;
    a.values[0] = 10;
    a.values[1] = 20;
    a.values[2] = 30;
    b.values[0] = 30;
    b.values[1] = 20;
    b.values[2] = 10;
    rgb avg = a.average(b);
    avg.print();
    assert(avg.values[0] == 20);
    assert(avg.values[1] == 20);
    assert(avg.values[2] == 20);
}