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.

extern(C) void gc_collect();

class C
{
  int i = 42;
}

C data;

void main()
{
  data = new C;
  gc_collect();
  assert(data.i == 42);
}