Fixed ModuleInfo generation to no longer use the ModuleInfo class' default initializer for types/defaults, it's unsafe as initializers don't necesarily match the "formal" type. There might be explicit padding. Changed -g switch to emit DW_LANG_D debug info, make demangling work with a patched GDB, still more work to do for full support of D's Dwarf extensions. Added getNullValue helper method.

module bug21;
extern(C) int printf(char*, ...);

void main()
{
    int i = 42;
    auto a = {
        int j = i*2;
        auto b = {
            return j;
        };
        return b();
    };
    int i2 = a();
    printf("%d\n", i2);
    assert(i2 == i*2);
}