[Ada] Fix internal error on locally derived bit-packed array type

[Eric Botcazou]

This is a regression present on the mainline, 11 and 10 branches, in the form 
of an ICE on a locally derived bit-packed array type.

Tested on x86-64/Linux, applied on the mainline, 11 and 10 branches.


2021-05-21  Eric Botcazou  <ebotca...@adacore.com>

        * gcc-interface/decl.c (gnat_to_gnu_entity) <E_Array_Type>: Process
        the implementation type of a packed type implemented specially.


2021-05-21  Eric Botcazou  <ebotca...@adacore.com>

        * gnat.dg/derived_type7.adb, gnat.dg/derived_type7.ads: New test.

-- 
Eric Botcazou
diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c
index 19e851ff712..8d3c16c624b 100644
--- a/gcc/ada/gcc-interface/decl.c
+++ b/gcc/ada/gcc-interface/decl.c
@@ -2345,11 +2345,15 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, bool definition)
 	      set_nonaliased_component_on_array_type (tem);
 	  }
 
-	/* If an alignment is specified, use it if valid.  But ignore it
-	   for the original type of packed array types.  If the alignment
-	   was requested with an explicit alignment clause, state so.  */
-	if (No (Packed_Array_Impl_Type (gnat_entity))
-	    && Known_Alignment (gnat_entity))
+	/* If this is a packed type implemented specially, then process the
+	   implementation type so it is elaborated in the proper scope.  */
+	if (Present (Packed_Array_Impl_Type (gnat_entity)))
+	  gnat_to_gnu_entity (Packed_Array_Impl_Type (gnat_entity), NULL_TREE,
+			      false);
+
+	/* Otherwise, if an alignment is specified, use it if valid and, if
+	   the alignment was requested with an explicit clause, state so.  */
+	else if (Known_Alignment (gnat_entity))
 	  {
 	    SET_TYPE_ALIGN (tem,
 			    validate_alignment (Alignment (gnat_entity),

-- { dg-do compile }

package Derived_Type7 is

  type Six_Bit_Data_Type is range 0 .. 63;
  for Six_Bit_Data_Type'Size use 6;

  type Six_Bit_Data_Array_Type is array (Integer range <>) of Six_Bit_Data_Type;
  for Six_Bit_Data_Array_Type'Component_Size use 6;

  procedure Proc (Size : Natural);

end Derived_Type7;

package body Derived_Type7 is

  procedure Proc (Size : Natural) is
    type Sar_Six_Bit_Arr is new Six_Bit_Data_Array_Type (1 .. Size);
  begin
    null;
  end;

end Derived_Type7;