E2458 Delphi classes have to be derived from Delphi classes (C++)
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You cannot derive a Delphi style class from a non-Delphi style class. Delphi style classes derive directly or indirectly from System::TObject.
Example:
struct base// base not a Delphi style class { intbasemem; }; struct __declspec(delphiclass) derived : base // or { intderivedmem; };