decl.c (components_to_record): Do not reuse the empty union type if there is a…

decl.c (components_to_record): Do not reuse the empty union type if there is a representation clause on the record.

	* decl.c (components_to_record): Do not reuse the empty union type
	if there is a representation clause on the record.
	* trans.c (addressable_p): Return true for INTEGER_CST.

From-SVN: r131733

gcc/ada/ChangeLog

+2008-01-22  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* decl.c (components_to_record): Do not reuse the empty union type
+	if there is a representation clause on the record.
+	* trans.c (addressable_p): Return true for INTEGER_CST.
+
 2008-01-21  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* trans.c (gnat_to_gnu) <N_Free_Statement>: Use POINTER_PLUS_EXPR

gcc/ada/decl.c

@@ -6007,11 +6007,15 @@ components_to_record (tree gnu_record_type, Node_Id component_list,
       gnu_union_name = concat_id_with_name (gnu_name,
 					    IDENTIFIER_POINTER (gnu_var_name));
 
-      if (!gnu_field_list && TREE_CODE (gnu_record_type) == UNION_TYPE)
+      /* Reuse an enclosing union if all fields are in the variant part
+	 and there is no representation clause on the record, to match
+	 the layout of C unions.  There is an associated check below.  */
+      if (!gnu_field_list
+	  && TREE_CODE (gnu_record_type) == UNION_TYPE
+	  && !TYPE_PACKED (gnu_record_type))
 	gnu_union_type = gnu_record_type;
       else
 	{
-
 	  gnu_union_type
 	    = make_node (unchecked_union ? UNION_TYPE : QUAL_UNION_TYPE);
 
@@ -6116,7 +6120,9 @@ components_to_record (tree gnu_record_type, Node_Id component_list,
 	     return.  */
 	  if (gnu_union_type == gnu_record_type)
 	    {
-	      gcc_assert (!gnu_field_list && unchecked_union);
+	      gcc_assert (unchecked_union
+			  && !gnu_field_list
+			  && !gnu_our_rep_list);
 	      return;
 	    }
 

gcc/ada/trans.c

@@ -6070,6 +6070,7 @@ addressable_p (tree gnu_expr)
     case INDIRECT_REF:
     case CONSTRUCTOR:
     case STRING_CST:
+    case INTEGER_CST:
     case NULL_EXPR:
     case SAVE_EXPR:
     case CALL_EXPR:

gcc/testsuite/ChangeLog

+2008-01-22  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/unchecked_union1.adb: New test.
+
 2008-01-22  Tom Tromey  <tromey@redhat.com>
 
 	PR c++/34829:

gcc/testsuite/gnat.dg/unchecked_union1.adb

+-- { dg-do run }
+
+procedure Unchecked_Union1 is
+
+  type Bit is (Zero, One);
+
+  type U (X : Bit := Zero) is record
+    case X is
+      when Zero => I: Integer;
+      when One => F : Float;
+    end case;
+  end record;
+  for U use record
+    I at 0 range  0 .. 31;
+    F at 0 range  0 .. 31;
+  end record;
+  pragma Unchecked_Union(U);
+
+begin
+  if U'Object_Size /= 32 then
+    raise Program_Error;
+  end if;
+end;