!752

!include #1002529 // Explain

answer {
  if "does this class have a default constructor: *" exceptionToUser {
   S java = m.unq(0);
    Explain explain = jExplainFull(java, "source");

    // make sure it's actually a class declaration
    //assertTrue("Bad class: " + explain.className(), litlist("classdecl", "emptyclass").contains(explain.className()));
    
    // go to class declaration instead
    Explain e2 = explain.findFirst("classdecl");
    if (e2 == null)
      ret "oops " + structure(explain);
    explain = e2;
    
    L<Explain> ctors = explain.findAll2("constructordecl");
    
    if (empty(ctors)) ret "Yes - an invisible one.";
    
    for (Explain ctor : ctors) {
      Explain args = ctor.findFirst("argsdecl2");
      if (args.findFirst("argsdecl") != null) // has arguments - not the default constructor
        continue;
      ret "Yes.";
    }
    
    ret "No.";
  }
}

Began life as a copy of #1002532