[Ada] No Storage_Error for an oversized disabled ghost array object

In some cases where the size computation for an object declaration will
unconditionally overflow, the FE generates code to raise Storage_Error
at the point of the object declaration (and may generate an associated
warning). Don't do this if the object declaration is an ignored (i.e.,
disabled) ghost declaration.

2019-09-18  Steve Baird  <baird@adacore.com>

gcc/ada/

	* freeze.adb (Freeze_Object_Declaration): Do not call
	Check_Large_Modular_Array when the object declaration being
	frozen is an ignored ghost entity.

gcc/testsuite/

	* gnat.dg/ghost7.adb, gnat.dg/ghost7.ads: New testcase.

From-SVN: r275845

gcc/ada/ChangeLog

+2019-09-18  Steve Baird  <baird@adacore.com>
+
+	* freeze.adb (Freeze_Object_Declaration): Do not call
+	Check_Large_Modular_Array when the object declaration being
+	frozen is an ignored ghost entity.
+
 2019-09-18  Tom Tromey  <tromey@adacore.com>
 
 	* make.adb (Initialize): Fix typo.

gcc/ada/freeze.adb

@@ -3569,7 +3569,8 @@ package body Freeze is
             Error_Msg_N ("\??use explicit size clause to set size", E);
          end if;
 
-         if Is_Array_Type (Typ) then
+         --  Declaring a too-big array in disabled ghost code is OK
+         if Is_Array_Type (Typ) and then not Is_Ignored_Ghost_Entity (E) then
             Check_Large_Modular_Array (Typ);
          end if;
       end Freeze_Object_Declaration;

gcc/testsuite/ChangeLog

+2019-09-18  Steve Baird  <baird@adacore.com>
+
+	* gnat.dg/ghost7.adb, gnat.dg/ghost7.ads: New testcase.
+
 2019-09-18  Olivier Hainque  <hainque@adacore.com>
 
 	* gnat.dg/system_info1.adb: New testcase.

gcc/testsuite/gnat.dg/ghost7.adb

+--  { dg-do compile }
+--  { dg-options "-gnatwa" }
+
+package body Ghost7 is
+   procedure Dummy is null;
+end Ghost7;

gcc/testsuite/gnat.dg/ghost7.ads

+pragma Restrictions (No_Exception_Propagation);
+
+package Ghost7 is
+   type Word64 is mod 2**64;
+   type My_Array_Type is array (Word64) of Boolean;
+   My_Array : My_Array_Type with Ghost;
+   procedure Dummy;
+end Ghost7;
\ No newline at end of file