C++: Support repeated initializers in dbscheme.

Author: sashabu

cpp/ql/lib/semmle/code/cpp/exprs/Literal.qll

@@ -192,7 +192,8 @@ class ClassAggregateLiteral extends AggregateLiteral {
    */
   Expr getFieldExpr(Field field) {
     field = classType.getAField() and
-    aggregate_field_init(underlyingElement(this), unresolveElement(result), unresolveElement(field))
+    aggregate_field_init(underlyingElement(this), unresolveElement(result), unresolveElement(field),
+      _)
   }
 
   /**
@@ -264,7 +265,7 @@ class ArrayOrVectorAggregateLiteral extends AggregateLiteral {
    * element `elementIndex`, if present.
    */
   Expr getElementExpr(int elementIndex) {
-    aggregate_array_init(underlyingElement(this), unresolveElement(result), elementIndex)
+    aggregate_array_init(underlyingElement(this), unresolveElement(result), elementIndex, _)
   }
 
   /**

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -1820,24 +1820,26 @@ new_array_allocated_type(
 
 /**
  * The field being initialized by an initializer expression within an aggregate
- * initializer for a class/struct/union.
+ * initializer for a class/struct/union. Position is used to sort repeated initializers.
  */
-#keyset[aggregate, field]
+#keyset[aggregate, position]
 aggregate_field_init(
     int aggregate: @aggregateliteral ref,
     int initializer: @expr ref,
-    int field: @membervariable ref
+    int field: @membervariable ref,
+    int position: int ref
 );
 
 /**
  * The index of the element being initialized by an initializer expression
- * within an aggregate initializer for an array.
+ * within an aggregate initializer for an array. Position is used to sort repeated initializers.
  */
-#keyset[aggregate, element_index]
+#keyset[aggregate, position]
 aggregate_array_init(
     int aggregate: @aggregateliteral ref,
     int initializer: @expr ref,
-    int element_index: int ref
+    int element_index: int ref,
+    int position: int ref
 );
 
 @ctorinit = @ctordirectinit