How to get around "access type must not be outside generic unit"

[Michael Erdmann <michael.erdmann@snafu.de>]

Dear all,

after installing the latest version of GNAT on my linux box i encounter
a problem with old source code. The Fragment below shows the problem:

---- usage.ads
generic
   type Data_Type is private;
package Usage is

   function Install return Boolean ;
   procedure Doit( X : in out Data_Type );
end Usage;

---- usage.adb
with Base;   use Base;

package body Usage is

   function Install return Boolean is
   begin
      return True;
   end Install;

   procedure Doit( X : in out Data_Type ) is
   begin
      null;
   end Doit;

begin
   Register("Doit", Install'Access);    <<<< offending line
end Usage;

gnade@hal:~/test> gnatmake -c usage.adb
gcc -c usage.adb
usage.adb:16:28: access type must not be outside generic unit
gnatmake: "usage.adb" compilation error

What is the reason for this new compiler check and what can i do
about it?

Regards
   M.Erdmann