[Ada] Spurious error reported by pragma Compile_Time_Error

[Ada] Spurious error reported by pragma Compile_Time_Error

The compiler may trigger spurious errors on pragmas Compile_Time_Error
and Compile_Time_Warning when their boolean expression computes the size
of a type. After this patch the following test compiles fine.

with Interfaces; use Interfaces;
package Types is
   type Arr is array (1 .. 6) of Unsigned_8
     with Size      => 48,
          Alignment => 1;

   type Rec is record
      Comp_1 : Unsigned_32;
      Comp_2 : Unsigned_16;
   end record
     with Size      => 48,
          Alignment => 1;
end Types;

with Types; use Types;
package Main is
   pragma Compile_Time_Error
     (Arr'Size  = 12, "ERROR: Arr'Size is 48, not 12");
   pragma Compile_Time_Error
     (Arr'Size  = 48, "OK: Arr");
   pragma Compile_Time_Error
     (Arr'Size /= 48, "ERROR: Arr'Size is 48");

   pragma Compile_Time_Error
     (Rec'Size  = 34, "ERROR: Rec'Size is 48, not 34");
   pragma Compile_Time_Error
     (Rec'Size  = 48, "OK: Rec");
   pragma Compile_Time_Error
     (Rec'Size /= 48, "ERROR: Rec'Size is 48");
end Main;

Command: gcc -c main.ads
 Output: main.ads:7:07: OK: Arr
         main.ads:14:07: OK: Rec

2019-07-08  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* sem_attr.adb (Analyze_Attribute [Attribute_Size]): For pragmas
	used to report user defined compile time warning or errors
	handle 'Size for types with known static RM size.

From-SVN: r273200