From e0a1d68279cff3100512dbc8dcd3e813ef9938d9 Mon Sep 17 00:00:00 2001
From: Shay Rojansky <roji@roji.org>
Date: Tue, 15 Oct 2019 13:00:03 +0200
Subject: [PATCH] Handle ListInitExpression in entity equality

Closes #18379
---
 .../EntityEqualityRewritingExpressionVisitor.cs      | 10 ++++++++++
 .../Query/SimpleQueryCosmosTest.Select.cs            | 10 ++++++++++
 .../Query/SimpleQueryTestBase.Select.cs              | 12 ++++++++++++
 .../Query/SimpleQuerySqlServerTest.Select.cs         |  9 +++++++++
 4 files changed, 41 insertions(+)

diff --git a/src/EFCore/Query/Internal/EntityEqualityRewritingExpressionVisitor.cs b/src/EFCore/Query/Internal/EntityEqualityRewritingExpressionVisitor.cs
index 1378e2d1bf9..8e121ccefc0 100644
--- a/src/EFCore/Query/Internal/EntityEqualityRewritingExpressionVisitor.cs
+++ b/src/EFCore/Query/Internal/EntityEqualityRewritingExpressionVisitor.cs
@@ -138,6 +138,16 @@ protected override Expression VisitMemberInit(MemberInitExpression memberInitExp
         protected override Expression VisitNewArray(NewArrayExpression newArrayExpression)
             => newArrayExpression.Update(Visit(newArrayExpression.Expressions).Select(Unwrap));
 
+        // Note that we could bubble up entity type information from the expressions initializing the list. However, EF Core doesn't
+        // actually support doing much further with this list, so it's not worth the complexity (right now). So we simply unwrap.
+        protected override Expression VisitListInit(ListInitExpression listInitExpression)
+            => listInitExpression.Update(
+                (NewExpression)Unwrap(listInitExpression.NewExpression),
+                listInitExpression.Initializers.Select(VisitElementInit));
+
+        protected override ElementInit VisitElementInit(ElementInit elementInit)
+            => Expression.ElementInit(elementInit.AddMethod, Visit(elementInit.Arguments).Select(Unwrap));
+
         protected override Expression VisitMember(MemberExpression memberExpression)
         {
             var visitedExpression = base.Visit(memberExpression.Expression);
diff --git a/test/EFCore.Cosmos.FunctionalTests/Query/SimpleQueryCosmosTest.Select.cs b/test/EFCore.Cosmos.FunctionalTests/Query/SimpleQueryCosmosTest.Select.cs
index 3cfaca4f489..1eaab854326 100644
--- a/test/EFCore.Cosmos.FunctionalTests/Query/SimpleQueryCosmosTest.Select.cs
+++ b/test/EFCore.Cosmos.FunctionalTests/Query/SimpleQueryCosmosTest.Select.cs
@@ -106,6 +106,16 @@ FROM root c
 WHERE (c[""Discriminator""] = ""Customer"")");
         }
 
+        public override async Task Projection_of_entity_type_into_object_list(bool isAsync)
+        {
+            await base.Projection_of_entity_type_into_object_list(isAsync);
+
+            AssertSql(
+                @"SELECT c
+FROM root c
+WHERE (c[""Discriminator""] = ""Customer"")");
+        }
+
         public override async Task Project_to_int_array(bool isAsync)
         {
             await base.Project_to_int_array(isAsync);
diff --git a/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.Select.cs b/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.Select.cs
index 10d6fa42825..e60be56eb90 100644
--- a/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.Select.cs
+++ b/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.Select.cs
@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.EntityFrameworkCore.Diagnostics;
@@ -90,6 +91,17 @@ public virtual Task Projection_of_multiple_entity_types_into_object_array(bool i
                 assertOrder: true);
         }
 
+        [ConditionalTheory]
+        [MemberData(nameof(IsAsyncData))]
+        public virtual Task Projection_of_entity_type_into_object_list(bool isAsync)
+        {
+            return AssertQuery(
+                isAsync,
+                ss => ss.Set<Customer>().Select(c => new List<object> { c }),
+                entryCount: 91,
+                assertOrder: true);
+        }
+
         [ConditionalTheory]
         [MemberData(nameof(IsAsyncData))]
         public virtual Task Project_to_int_array(bool isAsync)
diff --git a/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.Select.cs b/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.Select.cs
index 7087beceb63..ee4783187f0 100644
--- a/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.Select.cs
+++ b/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.Select.cs
@@ -102,6 +102,15 @@ WHERE [o].[OrderID] < 10300
 ORDER BY [o].[OrderID]");
         }
 
+        public override async Task Projection_of_entity_type_into_object_list(bool isAsync)
+        {
+            await base.Projection_of_entity_type_into_object_list(isAsync);
+
+            AssertSql(
+                @"SELECT [c].[CustomerID], [c].[Address], [c].[City], [c].[CompanyName], [c].[ContactName], [c].[ContactTitle], [c].[Country], [c].[Fax], [c].[Phone], [c].[PostalCode], [c].[Region]
+FROM [Customers] AS [c]");
+        }
+
         public override async Task Project_to_int_array(bool isAsync)
         {
             await base.Project_to_int_array(isAsync);