PS: Pipeline parameter and argument positions.

powershell/ql/lib/semmle/code/powershell/controlflow/CfgNodes.qll

@@ -213,6 +213,8 @@ module ExprNodes {
     override VarAccessChildMapping e;
 
     override VarAccess getExpr() { result = super.getExpr() }
+
+    Variable getVariable() { result = e.getVariable() }
   }
 
   private class VarReadAccessChildMapping extends VarAccessChildMapping, VarReadAccess { }
@@ -234,8 +236,6 @@ module ExprNodes {
 
     override VarWriteAccess getExpr() { result = super.getExpr() }
 
-    Variable getVariable() { result = e.getVariable() }
-
     predicate isExplicitWrite(StmtNodes::AssignStmtCfgNode assignment) {
       this = assignment.getLeftHandSide()
     }

powershell/ql/lib/semmle/code/powershell/dataflow/internal/DataFlowDispatch.qll

@@ -229,7 +229,8 @@ private module Cached {
         call = ns.getABindingCall() and
         exists(call.getArgument(pos))
       )
-    }
+    } or
+    TPipelineArgumentPosition()
 
   cached
   newtype TParameterPosition =
@@ -240,7 +241,8 @@ private module Cached {
         call = ns.getABindingCall() and
         exists(call.getArgument(pos))
       )
-    }
+    } or
+    TPipelineParameter()
 }
 
 import Cached
@@ -259,6 +261,8 @@ class ParameterPosition extends TParameterPosition {
   /** Holds if this parameter is a keyword parameter with `name`. */
   predicate isKeyword(string name) { this = TKeywordParameter(name) }
 
+  predicate isPipeline() { this = TPipelineParameter() }
+
   /** Gets a textual representation of this position. */
   string toString() {
     this.isThis() and result = "this"
@@ -268,6 +272,8 @@ class ParameterPosition extends TParameterPosition {
     )
     or
     exists(string name | this.isKeyword(name) and result = "kw(" + name + ")")
+    or
+    this.isPipeline() and result = "pipeline"
   }
 }
 
@@ -281,6 +287,8 @@ class ArgumentPosition extends TArgumentPosition {
 
   predicate isKeyword(string name) { this = TKeywordArgumentPosition(name) }
 
+  predicate isPipeline() { this = TPipelineArgumentPosition() }
+
   /** Gets a textual representation of this position. */
   string toString() {
     this.isThis() and result = "this"
@@ -290,6 +298,8 @@ class ArgumentPosition extends TArgumentPosition {
     )
     or
     exists(string name | this.isKeyword(name) and result = "kw(" + name + ")")
+    or
+    this.isPipeline() and result = "pipeline"
   }
 }
 
@@ -307,4 +317,6 @@ predicate parameterMatch(ParameterPosition ppos, ArgumentPosition apos) {
     ppos.isPositional(pos, ns) and
     apos.isPositional(pos, ns)
   )
+  or
+  ppos.isPipeline() and apos.isPipeline()
 }

powershell/ql/lib/semmle/code/powershell/dataflow/internal/DataFlowPrivate.qll

@@ -449,12 +449,18 @@ private module ParameterNodes {
         // keywords in S are specified.
         exists(int i, int j, string name, NamedSet ns, Function f |
           pos.isPositional(j, ns) and
-          parameter.getIndex() = i and
+          parameter.getIndexExcludingPipeline() = i and
           f = parameter.getFunction() and
           f = ns.getAFunction() and
           name = parameter.getName() and
           not name = ns.getAName() and
-          j = i - count(int k | k < i and f.getParameter(k).getName() = ns.getAName())
+          j =
+            i -
+              count(int k, Parameter p |
+                k < i and
+                p = f.getParameterExcludingPipline(k) and
+                p.getName() = ns.getAName()
+              )
         )
       )
     }