GCC 11 bug? lawyer needed

[Simon Wright <simon@pushface.org>]

This code results in the error shown:

     1. package Aliased_Tagged_Types is
     2.
     3.    type T is tagged null record;
     4.
     5.    function P (Param : aliased T) return Boolean
     6.      is (False);
     7.
     8.    function F (Param : T) return Boolean
     9.      is (Param.P);
                 |
        >>> actual for explicitly aliased formal is too short lived

    10.
    11. end Aliased_Tagged_Types;

The compiler code that results in this error is at sem_ch4.adb:1490, and
was introduced for Ada202x accessibiity checking reasons.

   --  Check whether the formal is aliased and if the accessibility
   --  level of the actual is deeper than the accessibility level
   --  of the enclosing subprogam to which the current return
   --  statement applies.

   [...]

   if Is_Explicitly_Aliased (Form)
     and then Is_Entity_Name (Act)
     and then Static_Accessibility_Level
                (Act, Zero_On_Dynamic_Level)
                  > Subprogram_Access_Level (Current_Subprogram)
   then
      Error_Msg_N ("actual for explicitly aliased formal is too"
                    & " short lived", Act);
   end if;

----

For those interested, this issue affects Alire.