unified: Expose getPostUpdateNode() to avoid internal import

Author: asgerf

unified/ql/lib/codeql/unified/internal/dataflow/DataFlowGraph.qll

@@ -148,7 +148,7 @@ module DebugGraph<relevantNodeSig/1 relevantNode> {
         if isUseStep = true then value = "use-use" else value = "def-use"
       )
       or
-      node2 = getPostUpdateNode(node1) and
+      node2 = node1.getPostUpdateNode() and
       value = "post-update"
     )
   }

unified/ql/lib/codeql/unified/internal/dataflow/DataFlowInstantiation.qll

@@ -101,9 +101,9 @@ module DataFlowInput implements InputSig<Location> {
   // Post-update nodes
   //
   class PostUpdateNode extends Node {
-    PostUpdateNode() { this = getPostUpdateNode(_) }
+    PostUpdateNode() { this = any(Node n).getPostUpdateNode() }
 
-    Node getPreUpdateNode() { this = getPostUpdateNode(result) }
+    Node getPreUpdateNode() { this = result.getPostUpdateNode() }
   }
 
   //

unified/ql/lib/codeql/unified/internal/dataflow/DataFlowNode.qll

@@ -315,21 +315,26 @@ class Node extends TDataFlowNode {
 
   /** Gets the basic block associated with this data flow node, if any. */
   BasicBlock getBasicBlock() { this.hasControlFlowPosition(result, _) }
-}
 
-Node getPostUpdateNode(Node pre) {
-  exists(Expr expr |
-    pre.isResultValue(expr) and
-    result.isPostUpdate(expr)
-  )
-  or
-  exists(Expr expr, LocalVariable var |
-    pre.isLocalVariableRead(expr, var) and
-    result.isLocalVariablePostUpdate(expr, var)
-  )
-  or
-  exists(DataFlowCall call |
-    pre.isReceiverArgumentEx(call) and
-    result.isReceiverPostUpdateEx(call)
-  )
+  /**
+   * Gets the post-update node for this node, if any.
+   *
+   * The post-update node represents the updated state of the value held in this node, after it has been mutated by the surrounding assignment or call.
+   */
+  Node getPostUpdateNode() {
+    exists(Expr expr |
+      this.isResultValue(expr) and
+      result.isPostUpdate(expr)
+    )
+    or
+    exists(Expr expr, LocalVariable var |
+      this.isLocalVariableRead(expr, var) and
+      result.isLocalVariablePostUpdate(expr, var)
+    )
+    or
+    exists(DataFlowCall call |
+      this.isReceiverArgumentEx(call) and
+      result.isReceiverPostUpdateEx(call)
+    )
+  }
 }

unified/ql/lib/codeql/unified/internal/dataflow/LocalSsa.qll

@@ -95,7 +95,7 @@ Node getNodeFromLocalSsaNode(Ssa::Node n) {
   result = n.(Ssa::ExprNode).getExpr() and
   not postUpdateReadNode(n)
   or
-  result = getPostUpdateNode(n.(Ssa::ExprPostUpdateNode).getExpr())
+  result = n.(Ssa::ExprPostUpdateNode).getExpr().(Node).getPostUpdateNode()
   or
   exists(LocalVariable v, BasicBlock bb, int i, AstNode repr |
     n.(Ssa::WriteDefSourceNode).getDefinition().definesAt(v, bb, i) and

unified/ql/lib/codeql/unified/internal/mad/LegacyMaD.qll

@@ -206,8 +206,6 @@ private DataFlow::Node getSinkFromCall(CallExpr call, AccessPathToken token) {
   result.isReceiverArgument(call)
 }
 
-private import codeql.unified.internal.dataflow.AllDataFlow
-
 /**
  * Gets the output from `call` specified by `token`. Only singleton access paths are supported.
  */
@@ -216,7 +214,7 @@ private DataFlow::Node getSourceFromCall(CallExpr call, AccessPathToken token) {
   token = "ReturnValue" and
   result.asExpr() = call
   or
-  result = getPostUpdateNode(getSinkFromCall(call, token))
+  result = getSinkFromCall(call, token).getPostUpdateNode()
 }
 
 /**