unified: Add union type and update CFG

Author: asgerf

unified/ql/lib/codeql/unified/internal/AstExtra.qll

@@ -6,29 +6,36 @@ private import unified
 private import codeql.unified.internal.NameBindingPlugin
 
 module Public {
+  /** An assignment, possibly a compound assignment. */
+  abstract class AssignmentImpl extends BinaryExpr {
+    /** Gets the target of this assignment. */
+    abstract Expr getTarget();
+
+    /** Gets the value assigned by this assignment. */
+    abstract Expr getValue();
+  }
+
+  final class Assignment = AssignmentImpl;
+
   /** A plain assignment expression. */
-  class AssignExpr extends BinaryExpr {
+  final class AssignExpr extends BinaryExpr, AssignmentImpl {
     AssignExpr() { this.getOperator().getValue() = "=" }
 
-    /** Gets the target of this assignment. */
-    Expr getTarget() { result = this.getLeft() }
+    override Expr getTarget() { result = this.getLeft() }
 
-    /** Gets the value assigned by this assignment. */
-    Expr getValue() { result = this.getRight() }
+    override Expr getValue() { result = this.getRight() }
   }
 
   /** A compound assignment expression. */
-  class CompoundAssignExpr extends BinaryExpr {
+  final class CompoundAssignExpr extends BinaryExpr, AssignmentImpl {
     CompoundAssignExpr() {
       this.getOperator().getValue() =
         ["+=", "-=", "*=", "/=", "%=", "<<=", ">>=", "&=", "|=", "^=", "&+=", "&-=", "&*="]
     }
 
-    /** Gets the target of this assignment. */
-    Expr getTarget() { result = this.getLeft() }
+    override Expr getTarget() { result = this.getLeft() }
 
-    /** Gets the value assigned by this assignment. */
-    Expr getValue() { result = this.getRight() }
+    override Expr getValue() { result = this.getRight() }
   }
 
   /** A short-circuiting logical AND expression. */

unified/ql/lib/codeql/unified/internal/ControlFlowGraph.qll

@@ -196,20 +196,23 @@ private module Ast implements AstSig<Location> {
 
   class LogicalNotExpr = U::LogicalNotExpr;
 
-  // TODO
-  class Assignment extends BinaryExpr {
-    Assignment() { none() }
-  }
+  class Assignment extends BinaryExpr, U::Assignment { }
 
-  class AssignExpr extends Assignment { }
+  class AssignExpr extends Assignment, U::AssignExpr { }
 
-  class CompoundAssignment extends Assignment { }
+  class CompoundAssignment extends Assignment, U::CompoundAssignExpr { }
 
-  class AssignLogicalAndExpr extends CompoundAssignment { }
+  class AssignLogicalAndExpr extends CompoundAssignment {
+    AssignLogicalAndExpr() { this.getOperator().getValue() = "&&=" }
+  }
 
-  class AssignLogicalOrExpr extends CompoundAssignment { }
+  class AssignLogicalOrExpr extends CompoundAssignment {
+    AssignLogicalOrExpr() { this.getOperator().getValue() = "||=" }
+  }
 
-  class AssignNullCoalescingExpr extends CompoundAssignment { }
+  class AssignNullCoalescingExpr extends CompoundAssignment {
+    AssignNullCoalescingExpr() { this.getOperator().getValue() = "??=" }
+  }
 
   class BooleanLiteral extends U::BooleanLiteral {
     boolean getValue() { result.toString() = super.getValue() }