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 mini.packed1;

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

align(1)
struct PackedStruct
{
    ubyte ub;
    float f;
    long l;
    short s;
    ubyte ub2;
    short s2;
}

void main()
{
    PackedStruct[2] a = void;
    void* begin = a.ptr;
    void* end = &a[1];
    ptrdiff_t sz = end - begin;
    printf("size = 18 = %u = %u\n", PackedStruct.sizeof, sz);
    assert(sz == 18);
}