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 arrays8;

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

void main()
{
    char[] a = "hello ";
    printf("  \"%s\".length = %u\n", a.ptr, a.length);
    char[] b = "world";
    printf("  \"%s\".length = %u\n", b.ptr, b.length);
    char[] c = a ~ b;
    printf("After 'a ~ b':\n");
    printf("  \"%.*s\".length = %u\n", a.length, a.ptr, a.length);
    printf("  \"%.*s\".length = %u\n", b.length, b.ptr, b.length);
    printf("  \"%.*s\".length = %u\n", c.length, c.ptr, c.length);
    assert(c.length == a.length + b.length);
    assert(c !is a);
    assert(c !is b);
}