如何在泛型类中声明枚举类型的集合类型

Question

I came across some strange behaviour in Delphi XE4.

I can't declare a set type within a generic class, where the ordinal type is declared within the same class.

For example:

TTest<T> = class(TObject)
type
  TEnumType  = (eOne, eTwo, eThree);
  TEnumTypes = set of TEnumType;
end;

The above does not compile. The compiler emits error " E2001: Ordinal type required ".

A non-generic class like

TTest = class(TObject)
type
  TEnumType  = (eOne, eTwo, eThree);
  TEnumTypes = set of TEnumType;
end;

does compile.

For the generic class to compile successfully, the ordinal type has to be declared outside the class:

TEnumType  = (eOne, eTwo, eThree);
TTest<T> = class(TObject)
type
  TEnumTypes = set of TEnumType;
end;

---

1. Is this behaviour considered a bug? If yes, has it been fixed in a later version?
2. Does anyone have another workaround? I wanted to declare the types within the class because they are used exclusively in private parts of this class.

Answer 1

This is indeed a bug that is fixed in later versions. Your code compiles in XE7 for instance. Quite possibly it will compile in XE5 or XE6, but I don't have them immediately to hand to check.

Answer 2

From looking at the issue tracker it seems to be a regression around XE3/XE4 which got fixed in later versions:

• http://qc.embarcadero.com/wc/qcmain.aspx?d=126675
• http://qc.embarcadero.com/wc/qcmain.aspx?d=112682
• http://qc.embarcadero.com/wc/qcmain.aspx?d=117200