Re: Accessibility Levels and Library-Level Units

["J-P. Rosen" <rosen@adalog.fr>]

Le 24/09/2013 21:27, Adam Beneschan a écrit :
> Even if the compiler knew Accessibility_Level_Test were the main
> subprogram, nothing would prevent some other subprogram from calling
> it (recursively).

Even without calling it recursively, exiting the main program is /not/
the end of the execution of an Ada Program. Tasks declared in library
packages continue to run, there are even programs where the main
procedure is begin-null;-end, all the work being done in library tasks.

And of course, such tasks could use the pointer after the main
subprogram is exited.

Library level finalizable objects can also execute code after the main
procedure is exited.

You can think of it this way: the real main program is written by the
compiler; it elaborates library packages, then calls the main procedure,
then finalizes library packages (which involves waiting for the
termination of library tasks).

In Gnat, this main program is written in Ada, and you can find it in the
b~xxx package.
-- 
J-P. Rosen
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