C++: Fix join order in getAnAssignedValue

Author: MathiasVP

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

@@ -115,6 +115,10 @@ class Variable extends Declaration, @variable {
     else result = this.getADeclarationLocation()
   }
 
+  /** Pulled out of `getAnAssignedValue` to fix a bad join order */
+  pragma[noinline]
+  private predicate aggregateLiteralHasType(AggregateLiteral lit, Class c) { lit.getType() = c }
+
   /**
    * Gets an expression that is assigned to this variable somewhere in the
    * program.
@@ -126,8 +130,9 @@ 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
+    exists(AggregateLiteral l, Class c |
+      this.(Field).getDeclaringType() = c and
+      aggregateLiteralHasType(l, c) and
       result = l.getChild(this.(Field).getInitializationOrder())
     )
   }