CSHARP-4040: Use AppContext switch to disable CSHARP-4040 validation

src/MongoDB.Bson/Serialization/BsonClassMap.cs

@@ -1337,6 +1337,11 @@ internal IDiscriminatorConvention GetDiscriminatorConvention()
 
             void EnsureNoMemberMapConflicts(string elementName)
             {
+                if (AppContext.TryGetSwitch("Switch.MongoDB.Driver.DisableDiscriminatorFieldConflictCheck", out bool disableConflictCheck) && disableConflictCheck)
+                {
+                    return;
+                }
+
                 var conflictingMemberMap = _allMemberMaps.FirstOrDefault(memberMap => memberMap.ElementName == elementName);
 
                 if (conflictingMemberMap != null)

tests/MongoDB.Driver.Tests/Linq/Linq3Implementation/Jira/CSharp4040SwitchTests.cs

@@ -0,0 +1,183 @@
+/* Copyright 2010-present MongoDB Inc.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using MongoDB.Driver.TestHelpers;
+using FluentAssertions;
+using MongoDB.Bson.Serialization;
+using MongoDB.Bson.Serialization.Conventions;
+using MongoDB.Bson.Serialization.Serializers;
+using MongoDB.Driver.Linq;
+using Xunit;
+
+namespace MongoDB.Driver.Tests.Linq.Linq3Implementation.Jira;
+
+public class CSharp4040SwitchTests : LinqIntegrationTest<CSharp4040SwitchTests.ClassFixture>, IDisposable
+{
+    static CSharp4040SwitchTests()
+    {
+        AppContext.SetSwitch("Switch.MongoDB.Driver.DisableDiscriminatorFieldConflictCheck", true);
+
+        var discriminatorConvention = new HierarchicalDiscriminatorConvention("TypeNames");
+
+        BsonClassMap.RegisterClassMap<C>(cm =>
+        {
+            cm.AutoMap();
+            cm.SetIsRootClass(true);
+            cm.SetDiscriminatorIsRequired(true);
+            cm.MapMember(x => x.TypeNames).SetShouldSerializeMethod(_ => false);
+            cm.SetDiscriminatorConvention(discriminatorConvention);
+        });
+    }
+
+    public void Dispose()
+    {
+        AppContext.SetSwitch("Switch.MongoDB.Driver.DisableDiscriminatorFieldConflictCheck", false);
+    }
+
+    public CSharp4040SwitchTests(ClassFixture fixture)
+        : base(fixture)
+    {
+    }
+
+    [Fact]
+    public void Documents_should_serializer_as_expected()
+    {
+        var collection = Fixture.Collection;
+
+        var seralizedDocuments = collection.AsQueryable().As(BsonDocumentSerializer.Instance).ToList();
+
+        seralizedDocuments.Count.Should().Be(2);
+        seralizedDocuments[0].Should().Be("{ _id : 1, TypeNames : ['C', 'D'] }");
+        seralizedDocuments[1].Should().Be("{ _id : 2, TypeNames : ['C', 'D', 'E'] }");
+    }
+
+    [Fact]
+    public void OfType_C_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .OfType<C>();
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, []);
+
+        var results = queryable.ToList();
+        results.Select(x => x.Id).Should().Equal(1, 2);
+    }
+
+    [Fact]
+    public void OfType_D_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .OfType<D>();
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, "{ $match : { TypeNames : 'D' } }");
+
+        var results = queryable.ToList();
+        results.Select(x => x.Id).Should().Equal(1, 2);
+    }
+
+    [Fact]
+    public void OfType_E_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .OfType<E>();
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, "{ $match : { TypeNames : 'E' } }");
+
+        var results = queryable.ToList();
+        results.Select(x => x.Id).Should().Equal(2);
+    }
+
+    [Fact]
+    public void Where_TypeNames_Contains_C_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Where(x => x.TypeNames.Contains("C"));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, "{ $match : { TypeNames : 'C' } }");
+
+        var results = queryable.ToList();
+        results.Select(x => x.Id).Should().Equal(1, 2);
+    }
+
+    [Fact]
+    public void Where_TypeNames_Contains_D_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Where(x => x.TypeNames.Contains("D"));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, "{ $match : { TypeNames : 'D' } }");
+
+        var results = queryable.ToList();
+        results.Select(x => x.Id).Should().Equal(1, 2);
+    }
+
+    [Fact]
+    public void Where_TypeNames_Contains_E_should_work()
+    {
+        var collection = Fixture.Collection;
+
+        var queryable = collection.AsQueryable()
+            .Where(x => x.TypeNames.Contains("E"));
+
+        var stages = Translate(collection, queryable);
+        AssertStages(stages, "{ $match : { TypeNames : 'E' } }");
+
+        var results = queryable.ToList();
+        results.Select(x => x.Id).Should().Equal(2);
+    }
+
+    public abstract class C
+    {
+        public int Id { get; set; }
+        public virtual IReadOnlyList<string> TypeNames => ["C"];
+    }
+
+    public class D : C
+    {
+        public override IReadOnlyList<string> TypeNames => ["C", "D"];
+    }
+
+    public class E : D
+    {
+        public override IReadOnlyList<string> TypeNames => ["C", "D", "E"];
+    }
+
+    public sealed class ClassFixture : MongoCollectionFixture<C>
+    {
+        protected override IEnumerable<C> InitialData =>
+        [
+            new D { Id = 1 },
+            new E { Id = 2 }
+        ];
+    }
+}