PS: Get rid of the pipelineVARIABLE and only have pipelinePARAMETER (and similarly for the by-propertyname versions).

Author: MathiasVP

powershell/ql/lib/semmle/code/powershell/ast/internal/Parameter.qll

@@ -34,23 +34,49 @@ class Parameter extends Variable instanceof ParameterImpl {
 
 class ThisParameter extends Parameter instanceof ThisParameterImpl { }
 
-class PipelineParameter extends Parameter {
-  PipelineParameter() { any(Synthesis s).isPipelineParameter(this) }
+/** The pipeline parameter of a function. */
+class PipelineParameter extends Parameter instanceof PipelineParameterImpl {
+  ScriptBlock getScriptBlock() { result = super.getScriptBlock() }
 }
 
-class PipelineByPropertyNameParameter extends Parameter {
-  PipelineByPropertyNameParameter() {
-    exists(NamedAttributeArgument namedAttribute |
-      this.getAnAttribute().(Attribute).getANamedArgument() = namedAttribute and
-      namedAttribute.getName().toLowerCase() = "valuefrompipelinebypropertyname"
-    |
-      namedAttribute.getValue().getValue().asBoolean() = true
-      or
-      not exists(namedAttribute.getValue().getValue().asBoolean())
-    )
-  }
+/**
+ * The iterator variable associated with a pipeline parameter.
+ * 
+ * This is the variable that is bound to the current element in the pipeline.
+ */
+class PipelineIteratorVariable extends Variable instanceof PipelineIteratorVariableImpl {
+  ProcessBlock getProcessBlock() { result = super.getProcessBlock() }
+}
+
+/**
+ * A pipeline-by-property-name parameter of a function.
+ */
+class PipelineByPropertyNameParameter extends Parameter instanceof PipelineByPropertyNameParameterImpl
+{
+  ScriptBlock getScriptBlock() { result = super.getScriptBlock() }
 
-  string getPropertyName() { result = this.getName() }
+  string getPropertyName() { result = super.getName() }
 
+  /**
+   * Gets the iterator variable that is used to iterate over the elements in the pipeline.
+   */
   PipelineByPropertyNameIteratorVariable getIteratorVariable() { result.getParameter() = this }
 }
+
+/**
+ * The iterator variable associated with a pipeline-by-property-name parameter.
+ * 
+ * This is the variable that is bound to the current element in the pipeline.
+ */
+class PipelineByPropertyNameIteratorVariable extends Variable instanceof PipelineByPropertyNameIteratorVariableImpl
+{
+  ProcessBlock getProcessBlock() { result = super.getProcessBlock() }
+
+  string getPropertyName() { result = super.getPropertyName() }
+
+  /**
+   * Gets the pipeline-by-property-name parameter that this variable
+   * iterates over.
+   */
+  PipelineByPropertyNameParameter getParameter() { result = super.getParameter() }
+}

powershell/ql/lib/semmle/code/powershell/ast/internal/Synthesis.qll

@@ -871,12 +871,12 @@ private module PipelineAccess {
     final override predicate child(Raw::Ast parent, ChildIndex i, Child child) {
       exists(Raw::ProcessBlock pb | parent = pb |
         i = processBlockPipelineVarReadAccess() and
-        exists(PipelineVariable pipelineVar |
-          pipelineVar = TVariableSynth(pb.getScriptBlock(), PipelineParamVar()) and
+        exists(PipelineParameter pipelineVar |
+          pipelineVar = getPipelineParameter(pb.getScriptBlock()) and
           child = SynthChild(VarAccessSynthKind(pipelineVar))
         )
         or
-        exists(PipelineByPropertyNameVariable pipelineVar, Raw::PipelineByPropertyNameParameter p |
+        exists(PipelineByPropertyNameParameter pipelineVar, Raw::PipelineByPropertyNameParameter p |
           i = processBlockPipelineByPropertyNameVarReadAccess(p.getName()) and
           getResultAst(p) = pipelineVar and
           child = SynthChild(VarAccessSynthKind(pipelineVar))

powershell/ql/lib/semmle/code/powershell/ast/internal/Variable.qll

@@ -54,10 +54,10 @@ module Private {
     override ThisVar i;
   }
 
-  class PipelineVariableImpl extends ParameterImpl {
+  class PipelineParameterImpl extends ParameterImpl {
     override FunParam i;
 
-    PipelineVariableImpl() {
+    PipelineParameterImpl() {
       exists(int index |
         i = FunParam(index) and
         any(Synthesis s).pipelineParameterHasIndex(super.getDeclaringScopeImpl(), index)
@@ -67,8 +67,8 @@ module Private {
     ScriptBlock getScriptBlock() { this = TVariableSynth(getRawAst(result), _) }
   }
 
-  class PipelineByPropertyNameVariableImpl extends ParameterImpl {
-    PipelineByPropertyNameVariableImpl() {
+  class PipelineByPropertyNameParameterImpl extends ParameterImpl {
+    PipelineByPropertyNameParameterImpl() {
       getRawAst(this) instanceof Raw::PipelineByPropertyNameParameter
     }
 
@@ -173,28 +173,6 @@ module Public {
   class VarReadAccess extends VarAccess {
     VarReadAccess() { not this instanceof VarWriteAccess }
   }
-
-  class PipelineByPropertyNameIteratorVariable extends Variable instanceof PipelineByPropertyNameIteratorVariableImpl
-  {
-    ProcessBlock getProcessBlock() { result = super.getProcessBlock() }
-
-    string getPropertyName() { result = super.getPropertyName() }
-
-    PipelineByPropertyNameParameter getParameter() { result = super.getParameter() }
-  }
-
-  class PipelineVariable extends Variable instanceof PipelineVariableImpl {
-    ScriptBlock getScriptBlock() { result = super.getScriptBlock() }
-  }
-
-  class PipelineByPropertyNameVariable extends Variable instanceof PipelineByPropertyNameVariableImpl
-  {
-    ScriptBlock getScriptBlock() { result = super.getScriptBlock() }
-  }
-
-  class PipelineIteratorVariable extends Variable instanceof PipelineIteratorVariableImpl {
-    ProcessBlock getProcessBlock() { result = super.getProcessBlock() }
-  }
 }
 
 import Public

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

@@ -291,11 +291,11 @@ class ProcessBlockCfgNode extends NamedBlockCfgNode {
 
   ScriptBlockCfgNode getScriptBlock() { result.getProcessBlock() = this }
 
-  PipelineVariable getPipelineVariable() {
+  PipelineParameter getPipelineParameter() {
     result.getScriptBlock() = this.getScriptBlock().getAstNode()
   }
 
-  ExprNodes::VarReadAccessCfgNode getPipelineVariableAccess() {
+  ExprNodes::VarReadAccessCfgNode getPipelineParameterAccess() {
     block.hasCfgChild(block.getPipelineParameterAccess(), this, result)
   }
 

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

@@ -164,7 +164,7 @@ module LocalFlow {
       nodeTo = TProcessPropertyByNameNode(pbNode.getAccess().getVariable(), false)
     )
     or
-    nodeTo.(PreProcessNode).getProcessBlock().getPipelineVariableAccess() = nodeFrom.asExpr()
+    nodeTo.(PreProcessNode).getProcessBlock().getPipelineParameterAccess() = nodeFrom.asExpr()
     or
     nodeTo.(ProcessNode).getProcessBlock() = nodeFrom.(PreProcessNode).getProcessBlock()
   }
@@ -1010,7 +1010,7 @@ predicate readStep(Node node1, ContentSet c, Node node2) {
   or
   c.isAnyPositional() and
   exists(CfgNodes::ProcessBlockCfgNode processBlock |
-    processBlock.getPipelineVariableAccess() = node1.asExpr() and
+    processBlock.getPipelineParameterAccess() = node1.asExpr() and
     node2 = TProcessNode(processBlock)
   )
   or