Merge pull request github#3334 from MathiasVP/get-an-assigned-value-join-order

C++: Fix join order in getAnAssignedValue

Author: jbj

cpp/ql/src/semmle/code/cpp/Variable.qll

@@ -126,10 +126,7 @@ class Variable extends Declaration, @variable {
     or
     exists(AssignExpr ae | ae.getLValue().(Access).getTarget() = this and result = ae.getRValue())
     or
-    exists(AggregateLiteral l |
-      this.getDeclaringType() = l.getType() and
-      result = l.getChild(this.(Field).getInitializationOrder())
-    )
+    exists(ClassAggregateLiteral l | result = l.getFieldExpr(this))
   }
 
   /**