Enhance ReviewUnusedParameter to bail out if $MyInvocation.BoundParameters encountered

Rules/ReviewUnusedParameter.cs

@@ -36,6 +36,12 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
 
             foreach (ScriptBlockAst scriptBlockAst in scriptBlockAsts)
             {
+                // bail out if PS bound parameter used.
+                if (scriptBlockAst.FindAll(IsBoundParametersReference, false).Any())
+                {
+                    continue;
+                }
+
                 // find all declared parameters
                 IEnumerable<Ast> parameterAsts = scriptBlockAst.FindAll(oneAst => oneAst is ParameterAst, false);
 
@@ -45,12 +51,6 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
                     .GroupBy(variableName => variableName, StringComparer.OrdinalIgnoreCase)
                     .ToDictionary(variableName => variableName.Key, variableName => variableName.Count(), StringComparer.OrdinalIgnoreCase);
 
-                // all bets are off if the script uses PSBoundParameters
-                if (variableCount.ContainsKey("PSBoundParameters"))
-                {
-                    continue;
-                }
-
                 foreach (ParameterAst parameterAst in parameterAsts)
                 {
                     // there should be at least two usages of the variable since the parameter declaration counts as one
@@ -72,6 +72,34 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
             }
         }
 
+        /// <summary>
+        /// Checks for PS bound parameter reference.
+        /// </summary>
+        /// <param name="ast"></param>
+        /// <returns></returns>
+        private static bool IsBoundParametersReference(Ast ast)
+        {
+            bool isBound = false;
+            // if $MyInvocation.BoundParameters or $PSCmdlet.MyInvocation.BoundParameters used.
+            if (ast is MemberExpressionAst memberAst
+                && memberAst.Member is StringConstantExpressionAst memberStringAst
+                && memberStringAst.Value.Equals("BoundParameters", StringComparison.OrdinalIgnoreCase))
+            {
+                // handle both regular and nested scenarios.
+                isBound = (memberAst.Expression is VariableExpressionAst veAst
+                    && veAst.VariablePath.UserPath.Equals("MyInvocation", StringComparison.OrdinalIgnoreCase))
+                    || (memberAst.Expression is MemberExpressionAst meAst
+                    && meAst.Expression is VariableExpressionAst veAstNested
+                    && veAstNested.VariablePath.UserPath.Equals("PSCmdlet", StringComparison.OrdinalIgnoreCase)
+                    && meAst.Member is StringConstantExpressionAst sceAstNested
+                    && sceAstNested.Value.Equals("MyInvocation", StringComparison.OrdinalIgnoreCase));
+            }
+
+            return isBound
+                || ast is VariableExpressionAst variableAst
+                && variableAst.VariablePath.UserPath.Equals("PSBoundParameters", StringComparison.OrdinalIgnoreCase);
+        }
+
         /// <summary>
         /// GetName: Retrieves the name of this rule.
         /// </summary>