Fix for parsing Guid and string in the same condition

src/System.Linq.Dynamic.Core/Parser/SupportedOperands/IEqualitySignatures.cs

@@ -13,9 +13,13 @@ internal interface IEqualitySignatures : IRelationalSignatures
 
         void F(Guid x, Guid y);
         void F(Guid? x, Guid? y);
-        void F(Guid x, string y);
-        void F(Guid? x, string y);
-        void F(string x, Guid y);
-        void F(string x, Guid? y);
+
+        // Disabled 2 lines below according to unit test ParseLambda_With_Guid_Equals_Null
+        //void F(Guid x, string y);
+        //void F(Guid? x, string y);
+
+        // Disabled 2 lines below according to unit test ParseLambda_With_Null_Equals_Guid
+        //void F(string x, Guid y);
+        //void F(string x, Guid? y);
     }
 }

test/System.Linq.Dynamic.Core.Tests/DynamicExpressionParserTests.cs

@@ -11,6 +11,8 @@ namespace System.Linq.Dynamic.Core.Tests
 {
     public class DynamicExpressionParserTests
     {
+
+
         private class MyClass
         {
             public int Foo()
@@ -452,5 +454,56 @@ public void ParseLambda_With_InnerStringLiteral()
             object result = del.DynamicInvoke(String.Empty);
             Check.That(result).IsEqualTo(originalTrueValue);
         }
+
+        [Fact]
+        public void ParseLambda_With_Guid_Equals_Null()
+        {
+            var user = new User();
+            Guid guidEmpty = Guid.Empty;
+            Guid someId = Guid.NewGuid();
+            string expressionText = $"iif(@0.Id == null, @0.Id == Guid.Parse(\"{someId}\"), Id == Id)";
+
+            var lambda = DynamicExpressionParser.ParseLambda(typeof(User), null, expressionText, user);
+            var boolLambda = lambda as Expression<Func<User, bool>>;
+            Assert.NotNull(boolLambda);
+
+            var del = lambda.Compile();
+            bool result = (bool) del.DynamicInvoke(user);
+            Assert.True(result);
+        }
+
+        [Fact]
+        public void ParseLambda_With_Null_Equals_Guid()
+        {
+            var user = new User();
+            Guid guidEmpty = Guid.Empty;
+            Guid someId = Guid.NewGuid();
+            string expressionText = $"iif(null == @0.Id, @0.Id == Guid.Parse(\"{someId}\"), Id == Id)";
+
+            var lambda = DynamicExpressionParser.ParseLambda(typeof(User), null, expressionText, user);
+            var boolLambda = lambda as Expression<Func<User, bool>>;
+            Assert.NotNull(boolLambda);
+
+            var del = lambda.Compile();
+            bool result = (bool) del.DynamicInvoke(user);
+            Assert.True(result);
+        }
+
+        [Fact]
+        public void ParseLambda_With_Guid_Equals_String()
+        {
+            Guid someId = Guid.NewGuid();
+            Guid anotherId = Guid.NewGuid();
+            var user = new User();
+            user.Id = someId;
+            Guid guidEmpty = Guid.Empty;
+            string expressionText = $"iif(@0.Id == \"{someId}\", Guid.Parse(\"{guidEmpty}\"), Guid.Parse(\"{anotherId}\"))";
+
+            var lambda = DynamicExpressionParser.ParseLambda(typeof(User), null, expressionText, user);
+
+            var del = lambda.Compile();
+            Guid result = (Guid) del.DynamicInvoke(user);
+            Assert.Equal(guidEmpty, result);
+        }
     }
 }