CSHARP-4118: Limit propagation of known serializers.

src/MongoDB.Driver/Linq/Linq3Implementation/Serializers/KnownSerializers/KnownSerializerFinder.cs

@@ -58,7 +58,7 @@ public override Expression Visit(Expression node)
                 return null;
             }
 
-            _currentKnownSerializersNode = new KnownSerializersNode(_currentKnownSerializersNode);
+            _currentKnownSerializersNode = new KnownSerializersNode(node, _currentKnownSerializersNode);
 
             if (node == _root)
             {

src/MongoDB.Driver/Linq/Linq3Implementation/Serializers/KnownSerializers/KnownSerializersNode.cs

@@ -16,25 +16,28 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Linq.Expressions;
 using MongoDB.Bson.Serialization;
 using MongoDB.Driver.Linq.Linq3Implementation.Misc;
-using MongoDB.Driver.Support;
 
 namespace MongoDB.Driver.Linq.Linq3Implementation.Serializers.KnownSerializers
 {
     internal class KnownSerializersNode
     {
         // private fields
+        private readonly Expression _expression;
         private readonly Dictionary<Type, HashSet<IBsonSerializer>> _knownSerializers = new Dictionary<Type, HashSet<IBsonSerializer>>();
         private readonly KnownSerializersNode _parent;
 
         // constructors
-        public KnownSerializersNode(KnownSerializersNode parent)
+        public KnownSerializersNode(Expression expression, KnownSerializersNode parent)
         {
+            _expression = expression;
             _parent = parent; // will be null for the root node
         }
 
         // public properties
+        public Expression Expression => _expression;
         public Dictionary<Type, HashSet<IBsonSerializer>> KnownSerializers => _knownSerializers;
         public KnownSerializersNode Parent => _parent;
 
@@ -49,7 +52,10 @@ public void AddKnownSerializer(Type type, IBsonSerializer serializer)
 
             set.Add(serializer);
 
-            _parent?.AddKnownSerializer(type, serializer);
+            if (ShouldPropagateKnownSerializerToParent())
+            {
+                _parent.AddKnownSerializer(type, serializer);
+            }
         }
 
         public HashSet<IBsonSerializer> GetPossibleSerializers(Type type)
@@ -109,5 +115,20 @@ private HashSet<IBsonSerializer> GetPossibleSerializersAtThisLevel(Type type)
 
             return possibleSerializers;
         }
+
+        private bool ShouldPropagateKnownSerializerToParent()
+        {
+            if (_parent == null)
+            {
+                return false;
+            }
+
+            return _parent.Expression.NodeType switch
+            {
+                ExpressionType.MemberInit => false,
+                ExpressionType.New => false,
+                _ => true
+            };
+        }
     }
 }

src/MongoDB.Driver/Linq/Linq3Implementation/Serializers/KnownSerializers/KnownSerializersRegistry.cs

@@ -29,7 +29,15 @@ internal class KnownSerializersRegistry
         // public methods
         public void Add(Expression expression, KnownSerializersNode knownSerializers)
         {
-            if (_registry.ContainsKey(expression)) return;
+            if (knownSerializers.Expression != expression)
+            {
+                throw new ArgumentException($"Expression {expression} does not match knownSerializers.Expression {knownSerializers.Expression}.");
+            }
+
+            if (_registry.ContainsKey(expression))
+            {
+                return;
+            }
 
             _registry.Add(expression, knownSerializers);
         }
@@ -41,8 +49,8 @@ public IBsonSerializer GetSerializer(Expression expression, IBsonSerializer defa
             return possibleSerializers.Count switch
             {
                 0 => defaultSerializer ?? BsonSerializer.LookupSerializer(expressionType), // sometimes there is no known serializer from the context (e.g. CSHARP-4062)
-                > 1 => throw new InvalidOperationException($"More than one possible serializer found for {expression}."),
-                _ => possibleSerializers.First()
+                1 => possibleSerializers.First(),
+                _ => throw new InvalidOperationException($"More than one possible serializer found for {expression}.")
             };
         }
     }

tests/MongoDB.Driver.Tests/Linq/Linq3ImplementationTests/Jira/CSharp4118Tests.cs

@@ -0,0 +1,60 @@
+/* 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.Linq;
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization.Attributes;
+using Xunit;
+
+namespace MongoDB.Driver.Tests.Linq.Linq3ImplementationTests.Jira
+{
+    public class CSharp4118Tests : Linq3IntegrationTest
+    {
+        [Fact]
+        public void Known_serializers_should_not_propagate_past_anonymous_class()
+        {
+            var collection = GetCollection<C>();
+            var queryable = collection.AsQueryable()
+                .Select(x => new { S = "abc", HasId = x.Id != "000000000000000000000000" });
+
+            var stages = Translate(collection, queryable);
+
+            AssertStages(stages, "{ $project : { S : 'abc', HasId : { $ne : ['$_id', ObjectId('000000000000000000000000')] }, _id : 0 } }");
+        }
+
+        [Fact]
+        public void Known_serializers_should_not_propagate_past_class_with_member_initializers()
+        {
+            var collection = GetCollection<C>();
+            var queryable = collection.AsQueryable()
+                .Select(x => new R { S = "abc", HasId = x.Id != "000000000000000000000000" });
+
+            var stages = Translate(collection, queryable);
+
+            AssertStages(stages, "{ $project : { S : 'abc', HasId : { $ne : ['$_id', ObjectId('000000000000000000000000')] }, _id : 0 } }");
+        }
+
+        private class C
+        {
+            [BsonRepresentation(BsonType.ObjectId)] public string Id { get; set; }
+        }
+
+        private class R
+        {
+            public string S { get; set; }
+            public bool HasId { get; set; }
+        }
+    }
+}