[Ada] Crash on constant declaration with variable size with generics

[Arnaud Charlet <charlet at adacore dot com>]

This change fixes a compiler crash occurring in some cases of constant
declarations initialized with a call to an instance of a generic function,
when the returned type is an array of dynamically sized elements.

The following compilation must be accepted quietly:

$ gcc -c p.adb
package Q is
   function F return Integer;
   subtype Comp is String (1 .. F);
   type Element_T is record
      C : Comp;
   end record;
end Q;

with Q;
procedure P is
   type Exist_Element_T (Exist : Boolean := False) is record
      case Exist is
         when True => Value : Q.Element_T;
         when False => null;
      end case;
   end record;

   type Arr is array (Boolean) of Exist_Element_T;

   generic
      type Idx is (<>);
      type Elmt is private;
      type Arr is array (Idx) of Elmt;
   function F_G return Arr;

   function F_G return Arr is
      A : Elmt;
   begin
      return Arr'(others => A);
   end F_G;

   function F is new F_G (Idx => Boolean, Elmt => Exist_Element_T, Arr => Arr);

   Const_Arr : constant Arr := F;

begin
   null;
end;

Tested on x86_64-pc-linux-gnu, committed on trunk

2014-01-22  Thomas Quinot  <quinot@adacore.com>

	* sem_ch3.adb (Analyze_Object_Declaration): For a constant
	declaration initialized with a function call, whose type
	has variable size, need to remove side effects so that the
	initialization expression becomes a dereference of a temporary
	reference to the function result.

Attachment: difs
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