[Dynamic Instrumentation] DEBUG-2365 Support string lexicographic com…

…parison (#5538) ## Summary of changes Allow the customer to use `<` `<=` `>` `>=` with strings in the EL ## Test coverage See tests in the PR
DataDog · Aug 5, 2024 · 9a4bfb5 · 9a4bfb5
1 parent bbac240
commit 9a4bfb5
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Showing 61 changed files with 874 additions and 237 deletions.
diff --git a/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParser.Binary.cs b/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParser.Binary.cs
@@ -59,6 +59,11 @@ private Expression BinaryOperation(JsonTextReader reader, List<ParameterExpressi
                 return ReturnDefaultValueExpression();
             }
 
+            if (left.Type == typeof(string) && right.Type == typeof(string))
+            {
+                return StringLexicographicComparison(left, right, operand);
+            }
+
             HandleDurationBinaryOperation(ref left, ref right);
 
             switch (operand)
@@ -98,4 +103,28 @@ private void HandleDurationBinaryOperation(ref Expression left, ref Expression r
             left = ConvertToDouble(left);
         }
     }
+
+    private Expression StringLexicographicComparison(Expression left, Expression right, string operand)
+    {
+        switch (operand)
+        {
+            case "==":
+                return Expression.Equal(left, right);
+            case "!=":
+                return Expression.NotEqual(left, right);
+        }
+
+        var compareOrdinal = Expression.Call(CompareOrdinalMethod(), new[] { left, right });
+        var zeroConstant = Expression.Constant(0);
+        return operand switch
+        {
+            ">" => Expression.GreaterThan(compareOrdinal, zeroConstant),
+            ">=" => Expression.GreaterThanOrEqual(compareOrdinal, zeroConstant),
+            "<" => Expression.LessThan(compareOrdinal, zeroConstant),
+            "<=" => Expression.LessThanOrEqual(compareOrdinal, zeroConstant),
+            _ => throw new ArgumentException("Unknown operand" + operand, nameof(operand))
+        };
+
+        System.Reflection.MethodInfo CompareOrdinalMethod() => ProbeExpressionParserHelper.GetMethodByReflection(typeof(string), "CompareOrdinal", new[] { typeof(string), typeof(string) });
+    }
 }
diff --git a/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParser.Dump.cs b/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParser.Dump.cs
@@ -13,6 +13,7 @@
 using Datadog.Trace.Debugger.Snapshots;
 using Datadog.Trace.Util;
 using static Datadog.Trace.Debugger.Expressions.ProbeExpressionParserHelper;
+using Enumerable = System.Linq.Enumerable;
 
 namespace Datadog.Trace.Debugger.Expressions;
 
@@ -125,14 +126,21 @@ private Expression DumpFieldsExpression(Expression expression, List<ParameterExp
     {
         const BindingFlags flags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance | BindingFlags.DeclaredOnly;
         var getTypeMethod = GetMethodByReflection(typeof(object), nameof(object.GetType), Type.EmptyTypes);
-        var getFieldsMethod = GetMethodByReflection(typeof(Type), nameof(Type.GetFields), new[] { typeof(BindingFlags) });
-        var getFields = Expression.Call(Expression.Call(expression, getTypeMethod), getFieldsMethod, Expression.Constant(flags));
-        var stringBuilderAppend = GetMethodByReflection(typeof(StringBuilder), nameof(StringBuilder.Append), new[] { typeof(string) });
+        var getFieldsMethod = GetMethodByReflection(typeof(Type), nameof(Type.GetFields), [typeof(BindingFlags)]);
+        var orderByMethod = GetMethodByReflection(typeof(System.Linq.Enumerable), nameof(System.Linq.Enumerable.OrderBy), [typeof(IEnumerable<>), typeof(Func<,>)], [typeof(FieldInfo), typeof(int)]);
+        var toArray = GetMethodByReflection(typeof(System.Linq.Enumerable), nameof(System.Linq.Enumerable.ToArray), [typeof(IEnumerable<>)], [typeof(FieldInfo)]);
+
+        ParameterExpression parameterExp = Expression.Parameter(typeof(FieldInfo), "fieldInfo");
+        MemberExpression propertyExp = Expression.Property(parameterExp, "MetadataToken");
+        Expression<Func<FieldInfo, int>> lambdaExp = Expression.Lambda<Func<FieldInfo, int>>(propertyExp, parameterExp);
+        var fieldInfoArray = Expression.Call(Expression.Call(expression, getTypeMethod), getFieldsMethod, Expression.Constant(flags));
+        var fieldInfoOrderedArray = Expression.Call(null, toArray, Expression.Call(null, orderByMethod, fieldInfoArray, lambdaExp));
+        var stringBuilderAppend = GetMethodByReflection(typeof(StringBuilder), nameof(StringBuilder.Append), [typeof(string)]);
         var expressions = new List<Expression>();
 
         var fields = Expression.Variable(typeof(FieldInfo[]), "fieldsArray");
         scopeMembers.Add(fields);
-        expressions.Add(Expression.Assign(fields, getFields));
+        expressions.Add(Expression.Assign(fields, fieldInfoOrderedArray));
 
         var result = Expression.Variable(typeof(StringBuilder), "fieldValues");
         scopeMembers.Add(result);

diff --git a/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParserHelper.cs b/tracer/src/Datadog.Trace/Debugger/Expressions/ProbeExpressionParserHelper.cs
@@ -5,6 +5,7 @@
 
 using System;
 using System.Collections.Concurrent;
+using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
 
@@ -16,19 +17,35 @@ internal static class ProbeExpressionParserHelper
 
     internal static readonly Type UndefinedValueType = typeof(UndefinedValue);
 
-    internal static MethodInfo GetMethodByReflection(Type type, string name, Type[] parametersTypes)
+    internal static MethodInfo GetMethodByReflection(Type type, string name, Type[] parametersTypes, Type[] genericArguments = null)
     {
         const BindingFlags bindingFlags = BindingFlags.Static | BindingFlags.Instance | BindingFlags.InvokeMethod |
                                           BindingFlags.NonPublic | BindingFlags.Public;
 
-        var reflectionMethodIdentifier = new ReflectionMethodIdentifier(type, name, parametersTypes);
+        var reflectionMethodIdentifier = new ReflectionMethodIdentifier(type, name, parametersTypes, genericArguments);
         return Methods.GetOrAdd(reflectionMethodIdentifier, GetMethodByReflectionInternal);
 
         MethodInfo GetMethodByReflectionInternal(ReflectionMethodIdentifier methodIdentifier)
         {
-            var method = parametersTypes == null ?
+            MethodInfo method = null;
+            if (genericArguments != null)
+            {
+                method = methodIdentifier.Type.GetMethods().
+                                          Where(m =>
+                                                    m.Name == methodIdentifier.MethodName &&
+                                                    m.GetParameters().Length == methodIdentifier.Parameters.Length &&
+                                                    m.ContainsGenericParameters &&
+                                                    m.GetGenericArguments().Length == methodIdentifier.GenericArguments.Length).
+                                          SingleOrDefault(m => m.GetParameters().Select(pi => pi.ParameterType.Name).SequenceEqual(methodIdentifier.Parameters.Select(p => p.Name)));
+
+                method = method?.MakeGenericMethod(methodIdentifier.GenericArguments);
+            }
+            else
+            {
+                method = parametersTypes == null ?
                              methodIdentifier.Type.GetMethod(methodIdentifier.MethodName, bindingFlags) :
                              methodIdentifier.Type.GetMethod(methodIdentifier.MethodName, bindingFlags, null, methodIdentifier.Parameters, null);
+            }
 
             if (method == null)
             {
@@ -41,18 +58,21 @@ MethodInfo GetMethodByReflectionInternal(ReflectionMethodIdentifier methodIdenti
 
     internal readonly record struct ReflectionMethodIdentifier
     {
-        internal ReflectionMethodIdentifier(Type type, string methodName, Type[] parameters)
+        internal ReflectionMethodIdentifier(Type type, string methodName, Type[] parameters, Type[] genericArguments)
         {
             Type = type;
             MethodName = methodName;
             Parameters = parameters;
+            GenericArguments = genericArguments;
         }
 
         internal Type Type { get; }
 
         internal string MethodName { get; }
 
         internal Type[] Parameters { get; }
+
+        internal Type[] GenericArguments { get; }
     }
 
     internal readonly ref struct ExpressionBodyAndParameters

diff --git a/tracer/test/Datadog.Trace.Tests/Debugger/DebuggerExpressionLanguageTests.cs b/tracer/test/Datadog.Trace.Tests/Debugger/DebuggerExpressionLanguageTests.cs
@@ -43,6 +43,8 @@ public DebuggerExpressionLanguageTests()
                 IntNumber = 42,
                 DoubleNumber = 3.14159,
                 String = "Hello world!",
+                Char = 'C',
+                AnotherChar = 'A',
                 BooleanValue = true,
                 Null = null,
                 Nested = new TestStruct.NestedObject { NestedString = "Hello from nested object", Nested = new TestStruct.NestedObject { NestedString = "Hello from another nested object" } },
@@ -192,7 +194,7 @@ private string GetJsonPart(string json)
 
         private MethodScopeMembers CreateScopeMembers()
         {
-            var scope = new MethodScopeMembers(5, 5);
+            var scope = new MethodScopeMembers(10, 5);
 
             // Add locals
             scope.AddMember(new ScopeMember("IntLocal", TestObject.IntNumber.GetType(), TestObject.IntNumber, ScopeMemberKind.Local));
@@ -203,6 +205,8 @@ private MethodScopeMembers CreateScopeMembers()
             scope.AddMember(new ScopeMember("NestedObjectLocal", TestObject.Nested.GetType(), TestObject.Nested, ScopeMemberKind.Local));
             scope.AddMember(new ScopeMember("NullLocal", TestObject.Nested.GetType(), TestObject.Null, ScopeMemberKind.Local));
             scope.AddMember(new ScopeMember("BooleanValue", TestObject.BooleanValue.GetType(), TestObject.BooleanValue, ScopeMemberKind.Local));
+            scope.AddMember(new ScopeMember("Char", TestObject.Char.GetType(), TestObject.Char, ScopeMemberKind.Local));
+            scope.AddMember(new ScopeMember("AnotherChar", TestObject.AnotherChar.GetType(), TestObject.AnotherChar, ScopeMemberKind.Local));
 
             // Add arguments
             scope.AddMember(new ScopeMember("IntArg", TestObject.IntNumber.GetType(), TestObject.IntNumber, ScopeMemberKind.Argument));
@@ -328,6 +332,10 @@ internal struct TestStruct
 
             public string String;
 
+            public char Char;
+
+            public char AnotherChar;
+
             public NestedObject Nested;
 
             public ChildNestedObject ChildNested;

diff --git a/...ressionsResources/Approvals/DebuggerExpressionLanguageTests.AccessNullObject.verified.txt b/...ressionsResources/Approvals/DebuggerExpressionLanguageTests.AccessNullObject.verified.txt
@@ -29,11 +29,13 @@ Expressions:
     var NestedObjectLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[5].Value;
     var NullLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[6].Value;
     var BooleanValue = (bool)scopeMemberArray[7].Value;
-    var IntArg = (int)scopeMemberArray[8].Value;
-    var DoubleArg = (double)scopeMemberArray[9].Value;
-    var StringArg = (string)scopeMemberArray[10].Value;
-    var CollectionArg = (List<string>)scopeMemberArray[11].Value;
-    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[12].Value;
+    var Char = (char)scopeMemberArray[8].Value;
+    var AnotherChar = (char)scopeMemberArray[9].Value;
+    var IntArg = (int)scopeMemberArray[10].Value;
+    var DoubleArg = (double)scopeMemberArray[11].Value;
+    var StringArg = (string)scopeMemberArray[12].Value;
+    var CollectionArg = (List<string>)scopeMemberArray[13].Value;
+    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[14].Value;
     var $dd_el_result = this.Null.NestedString;
 
     return $dd_el_result;

diff --git a/...ssionsResources/Approvals/DebuggerExpressionLanguageTests.ChildPrivateMember.verified.txt b/...ssionsResources/Approvals/DebuggerExpressionLanguageTests.ChildPrivateMember.verified.txt
@@ -35,11 +35,13 @@ Expressions:
     var NestedObjectLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[5].Value;
     var NullLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[6].Value;
     var BooleanValue = (bool)scopeMemberArray[7].Value;
-    var IntArg = (int)scopeMemberArray[8].Value;
-    var DoubleArg = (double)scopeMemberArray[9].Value;
-    var StringArg = (string)scopeMemberArray[10].Value;
-    var CollectionArg = (List<string>)scopeMemberArray[11].Value;
-    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[12].Value;
+    var Char = (char)scopeMemberArray[8].Value;
+    var AnotherChar = (char)scopeMemberArray[9].Value;
+    var IntArg = (int)scopeMemberArray[10].Value;
+    var DoubleArg = (double)scopeMemberArray[11].Value;
+    var StringArg = (string)scopeMemberArray[12].Value;
+    var CollectionArg = (List<string>)scopeMemberArray[13].Value;
+    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[14].Value;
 
     return "UndefinedValue";
 }

diff --git a/...sResources/Approvals/DebuggerExpressionLanguageTests.ChildStaticPublicMember.verified.txt b/...sResources/Approvals/DebuggerExpressionLanguageTests.ChildStaticPublicMember.verified.txt
@@ -35,11 +35,13 @@ Expressions:
     var NestedObjectLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[5].Value;
     var NullLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[6].Value;
     var BooleanValue = (bool)scopeMemberArray[7].Value;
-    var IntArg = (int)scopeMemberArray[8].Value;
-    var DoubleArg = (double)scopeMemberArray[9].Value;
-    var StringArg = (string)scopeMemberArray[10].Value;
-    var CollectionArg = (List<string>)scopeMemberArray[11].Value;
-    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[12].Value;
+    var Char = (char)scopeMemberArray[8].Value;
+    var AnotherChar = (char)scopeMemberArray[9].Value;
+    var IntArg = (int)scopeMemberArray[10].Value;
+    var DoubleArg = (double)scopeMemberArray[11].Value;
+    var StringArg = (string)scopeMemberArray[12].Value;
+    var CollectionArg = (List<string>)scopeMemberArray[13].Value;
+    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[14].Value;
 
     return "UndefinedValue";
 }

diff --git a/...obeExpressionsResources/Approvals/DebuggerExpressionLanguageTests.Collection.verified.txt b/...obeExpressionsResources/Approvals/DebuggerExpressionLanguageTests.Collection.verified.txt
@@ -26,11 +26,13 @@ Expressions:
     var NestedObjectLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[5].Value;
     var NullLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[6].Value;
     var BooleanValue = (bool)scopeMemberArray[7].Value;
-    var IntArg = (int)scopeMemberArray[8].Value;
-    var DoubleArg = (double)scopeMemberArray[9].Value;
-    var StringArg = (string)scopeMemberArray[10].Value;
-    var CollectionArg = (List<string>)scopeMemberArray[11].Value;
-    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[12].Value;
+    var Char = (char)scopeMemberArray[8].Value;
+    var AnotherChar = (char)scopeMemberArray[9].Value;
+    var IntArg = (int)scopeMemberArray[10].Value;
+    var DoubleArg = (double)scopeMemberArray[11].Value;
+    var StringArg = (string)scopeMemberArray[12].Value;
+    var CollectionArg = (List<string>)scopeMemberArray[13].Value;
+    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[14].Value;
     var $dd_el_result =
     {
         enumerator = this.Collection.GetEnumerator();

diff --git a/...pressionsResources/Approvals/DebuggerExpressionLanguageTests.CollectionCount.verified.txt b/...pressionsResources/Approvals/DebuggerExpressionLanguageTests.CollectionCount.verified.txt
@@ -28,11 +28,13 @@ Expressions:
     var NestedObjectLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[5].Value;
     var NullLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[6].Value;
     var BooleanValue = (bool)scopeMemberArray[7].Value;
-    var IntArg = (int)scopeMemberArray[8].Value;
-    var DoubleArg = (double)scopeMemberArray[9].Value;
-    var StringArg = (string)scopeMemberArray[10].Value;
-    var CollectionArg = (List<string>)scopeMemberArray[11].Value;
-    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[12].Value;
+    var Char = (char)scopeMemberArray[8].Value;
+    var AnotherChar = (char)scopeMemberArray[9].Value;
+    var IntArg = (int)scopeMemberArray[10].Value;
+    var DoubleArg = (double)scopeMemberArray[11].Value;
+    var StringArg = (string)scopeMemberArray[12].Value;
+    var CollectionArg = (List<string>)scopeMemberArray[13].Value;
+    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[14].Value;
     var $dd_el_result = CollectionLocal.Count.ToString();
 
     return $dd_el_result;

diff --git a/...pressionsResources/Approvals/DebuggerExpressionLanguageTests.CollectionIndex.verified.txt b/...pressionsResources/Approvals/DebuggerExpressionLanguageTests.CollectionIndex.verified.txt
@@ -29,11 +29,13 @@ Expressions:
     var NestedObjectLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[5].Value;
     var NullLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[6].Value;
     var BooleanValue = (bool)scopeMemberArray[7].Value;
-    var IntArg = (int)scopeMemberArray[8].Value;
-    var DoubleArg = (double)scopeMemberArray[9].Value;
-    var StringArg = (string)scopeMemberArray[10].Value;
-    var CollectionArg = (List<string>)scopeMemberArray[11].Value;
-    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[12].Value;
+    var Char = (char)scopeMemberArray[8].Value;
+    var AnotherChar = (char)scopeMemberArray[9].Value;
+    var IntArg = (int)scopeMemberArray[10].Value;
+    var DoubleArg = (double)scopeMemberArray[11].Value;
+    var StringArg = (string)scopeMemberArray[12].Value;
+    var CollectionArg = (List<string>)scopeMemberArray[13].Value;
+    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[14].Value;
     var $dd_el_result = (string)CollectionLocal[0];
 
     return $dd_el_result;

diff --git a/...esources/Approvals/DebuggerExpressionLanguageTests.CollectionIndexOutOfRange.verified.txt b/...esources/Approvals/DebuggerExpressionLanguageTests.CollectionIndexOutOfRange.verified.txt
@@ -29,11 +29,13 @@ Expressions:
     var NestedObjectLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[5].Value;
     var NullLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[6].Value;
     var BooleanValue = (bool)scopeMemberArray[7].Value;
-    var IntArg = (int)scopeMemberArray[8].Value;
-    var DoubleArg = (double)scopeMemberArray[9].Value;
-    var StringArg = (string)scopeMemberArray[10].Value;
-    var CollectionArg = (List<string>)scopeMemberArray[11].Value;
-    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[12].Value;
+    var Char = (char)scopeMemberArray[8].Value;
+    var AnotherChar = (char)scopeMemberArray[9].Value;
+    var IntArg = (int)scopeMemberArray[10].Value;
+    var DoubleArg = (double)scopeMemberArray[11].Value;
+    var StringArg = (string)scopeMemberArray[12].Value;
+    var CollectionArg = (List<string>)scopeMemberArray[13].Value;
+    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[14].Value;
     var $dd_el_result = (string)CollectionLocal[100];
 
     return $dd_el_result;

diff --git a/...sionsResources/Approvals/DebuggerExpressionLanguageTests.CompareStringAndInt.verified.txt b/...sionsResources/Approvals/DebuggerExpressionLanguageTests.CompareStringAndInt.verified.txt
@@ -0,0 +1,55 @@
+Condition:
+Json:
+{
+    "gt": [
+      {
+        "getmember": [
+          {
+            "ref": "this"
+          },
+          "String"
+        ]
+      },
+      {
+        "getmember": [
+          {
+            "ref": "this"
+          },
+          "IntNumber"
+        ]
+      }
+    ]
+  }
+Expression: (
+    scopeMember,
+    scopeMember,
+    scopeMember,
+    exception,
+    scopeMemberArray) =>
+{
+    bool $dd_el_result;
+    var this = (DebuggerExpressionLanguageTests.TestStruct)scopeMember.Value;
+    var @return = (string)scopeMember.Value;
+    var @duration = (TimeSpan)scopeMember.Value;
+    var @exception = exception;
+    var IntLocal = (int)scopeMemberArray[0].Value;
+    var DoubleLocal = (double)scopeMemberArray[1].Value;
+    var StringLocal = (string)scopeMemberArray[2].Value;
+    var CollectionLocal = (List<string>)scopeMemberArray[3].Value;
+    var DictionaryLocal = (Dictionary<string, string>)scopeMemberArray[4].Value;
+    var NestedObjectLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[5].Value;
+    var NullLocal = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[6].Value;
+    var BooleanValue = (bool)scopeMemberArray[7].Value;
+    var Char = (char)scopeMemberArray[8].Value;
+    var AnotherChar = (char)scopeMemberArray[9].Value;
+    var IntArg = (int)scopeMemberArray[10].Value;
+    var DoubleArg = (double)scopeMemberArray[11].Value;
+    var StringArg = (string)scopeMemberArray[12].Value;
+    var CollectionArg = (List<string>)scopeMemberArray[13].Value;
+    var NestedObjectArg = (DebuggerExpressionLanguageTests.TestStruct.NestedObject)scopeMemberArray[14].Value;
+
+    return true;
+}
+Result: True
+Errors:
+EvaluationError { Expression = this.String > this.IntNumber, Message = The binary operator GreaterThan is not defined for the types 'System.String' and 'System.Int32'. }