As reported on the Debian BTS as #131331
(http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=131331) by Jochen Voss:

========================================================================

Hello,

when I use an CORBA <enum_type> as a union discriminator,
orbit-idl silently generates code, which does not compile.

Example: I use the following IDL file:

== testunion.idl starts at next line =================================
module TestUnion {
  interface Frosch {
    union MyUnion switch (enum E2 { A, B }) {
    case A:
      long x;
    case B: 
      string s;
    };

    attribute MyUnion U;
  };
};
== testunion.idl ends at previous line ===============================

Now I call orbit-idl:

    voss@tatonka [~/bugreport/orbit] orbit-idl testunion.idl 
    voss@tatonka [~/bugreport/orbit] grep TestUnion_Frosch_MyUnion_E2 *
    testunion-common.c:static const TestUnion_Frosch_MyUnion_E2
anon_sublabel_values_array8[] =
    testunion-common.c:   { {(CORBA_TypeCode) &
TC_TestUnion_Frosch_MyUnion_E2_struct,
    testunion-common.c:   {(CORBA_TypeCode) &
TC_TestUnion_Frosch_MyUnion_E2_struct,
    testunion-common.c:   (CORBA_TypeCode) &
TC_TestUnion_Frosch_MyUnion_E2_struct, 0, -1, 0, 0
    testunion-skels.c:       value._d = *((TestUnion_Frosch_MyUnion_E2 *)
_ORBIT_curptr);
    testunion-stubs.c:          *((TestUnion_Frosch_MyUnion_E2 *)
_ORBIT_curptr);
    testunion.h:      TestUnion_Frosch_MyUnion_E2 _d;

As you can see, TestUnion_Frosch_MyUnion_E2 is never defined,
but used in severl places.  Consequently the generated files
refuse to compile.

Jochen