Setting enumeration-indexed vector in derived model

I define

type Enum = enumeration(A, B, C);

and

partial model PM
  parameter Real[Enum] a;
...
end PM;

and

model M
  extends PM(a = {1, 2, 3});
...
end M;

which gives an error. My best guess is that the a = {1, 2, 3} is the culprit. Is this indeed illegal, and if so, how can I set a in M?

UPDATE

Upon further examination I've found that everything above is indeed legal. Let me just go the whole hog:

type Enum = enumeration(A, B, C);

connector Conn
  Real[Enum] a;
  flow Real[Enum] f;
end Conn;

model M1
  Conn conn;
equation
  conn.f = -conn.a;
end M1;

model M2
  Conn conn;
initial equation
  conn.a = {1, 2, 3};
equation
  der(conn.a) = conn.f;
end M2;

model M3
  M1 m1;
  M2 m2;
equation
  connect(m1.conn, m2.conn);
end M3;

This fails to build. But if I just change each Enum in the connector class to 3, then it works.

Solution

The example is (as far as I can tell) legal, and some tools already handle it (assuming there is nothing else hidden).

Since you need a tool-specific work-around you need to specify which tool.

The legality will be clarified further in later versions of the Modelica specification since it was unclear - https://trac.modelica.org/Modelica/ticket/2212#comment:3