DDSXTY13 — Type compatibility when members types define keys

Assume the following:

@appendable
struct T1 {
   @key long m1; 
}

@appendable
struct T2 {
  @key long m2;
  @key long m3;
}

struct MyType1  {
  T1 t1; 
  long ll1;
} 

struct MyType2  {
  T2 t1;
  long ll1;
}

According to the type-compatibility rules MyType1 and MyType2 are not compatible because T1 is not compatible with T2.

The reason T1 is not compatible with T2 is due to having different keys. But the keys of T1 and T2 do not play any role in MyType1 and MyType2 because these types did not declare those respective member as key.

So the current compatibility rules are too restrictive. They should be amended to allow MyType1 and MyType2 to be compatible.

Modify type compatibility rules for Aggregated Types

Modify the type assignability rules to differentiate the requirements form members that are part of the key of the aggregated type from those that are not part of the key.

The assignability of members that are not part of the key of the enclosing type should not take into consideration the key members of the nested type.