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 bug33;

extern(C) int memcmp(void*,void*,size_t);

private int string_cmp(char[] s1, char[] s2)
{
    auto len = s1.length;
    if (s2.length < len)
        len = s2.length;
    int result = memcmp(s1.ptr, s2.ptr, len);
    if (result == 0)
        result = cast(int)(cast(ptrdiff_t)s1.length - cast(ptrdiff_t)s2.length);
    return result;
}

struct S
{
    char[] toString()
    {
        return "S";
    }
}

int func()
{
    S a,b;
    return string_cmp(a.toString(),b.toString());
}

void main()
{
    assert(func() == 0);
}