Methods declared in a dispinterface type cannot specify any calling convention directives.

program Produce;

  type
    IBase = dispinterface
    ['{00000000-0000-0000-0000-000000000000}']
      procedure yamadama; register;
    end;

begin
end.

The error in the example shown here is that the method 'yamadama' attempts to specify the register calling convention.

program Solve;

  type
    IBase = dispinterface
    ['{00000000-0000-0000-0000-000000000000}']
      procedure yamadama;
    end;

begin
end.

Since no dispinterface method can specify calling convention directives, the only solution to this problem is to remove the offending directive, as shown in this example.