I have the following code that doesn't compile, and I can't find an explanation as to why.

TIndexArray<TType> = array of TType;

TIndexList<TArrayType; TType: TIndexArray<TArrayType>> = class
end;

It says the

Type 'TIndexArray' is not a valid constraint.

But if TIndexArray is a class and not an array type it works.

CodePudding user response：

Array types are not supported as constraints. This is documented behavior:

https://docwiki.embarcadero.com/RADStudio/en/Constraints_in_Generics

Constraint items include:

• Zero, one, or multiple interface types

• Zero or one class type

• The reserved word "constructor", "class", or "record"

No mention of array types.