(layout_record): After copying the offsets of a field that is an anonymous union…

(layout_record): After copying the offsets of a field that is an anonymous union to the offsets of the fields of that union...

(layout_record): After copying the offsets of a field that is an
anonymous union to the offsets of the fields of that union, zero the
offset of the anonymous field in case it is used to access the inner
fields.

From-SVN: r4083

gcc/stor-layout.c

@@ -435,7 +435,17 @@ layout_record (rec)
 	DECL_FIELD_BITPOS (field) = size_int (const_size);
 
       /* If this field is an anonymous union,
-	 give each union-member the same position as the union has.  */
+	 give each union-member the same position as the union has.
+
+	 ??? This is a real kludge because it makes the structure
+	 of the types look strange.  This feature is only used by
+	 C++, which should have build_component_ref build two
+	 COMPONENT_REF operations, one for the union and one for
+	 the inner field.  We set the offset of this field to zero
+	 so that either the old or the correct method will work.
+	 Setting DECL_FIELD_CONTEXT is wrong unless the inner fields are
+	 moved into the type of this field, but nothing seems to break
+	 by doing this.  This kludge should be removed after 2.4.  */
 
       if (DECL_NAME (field) == 0
 	  && TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
@@ -446,6 +456,8 @@ layout_record (rec)
 	      DECL_FIELD_CONTEXT (uelt) = DECL_FIELD_CONTEXT (field);
 	      DECL_FIELD_BITPOS (uelt) = DECL_FIELD_BITPOS (field);
 	    }
+
+	  DECL_FIELD_BITPOS (field) = integer_zero_node;
 	}
 
       /* Now add size of this field to the size of the record.  */