Contains() throws Exception Expression of type 'System.Collections.Generic.List`1[System.Int32]' cannot be used for parameter...

[kccsf]

Contains() is throwing an exception when used as follows:

var posts = await context.Post
    .Where(x => blogs.Contains(x.Blog))
    .ToListAsync();

Exception message: "Expression of type 'System.Collections.Generic.List1[System.Int32]' cannot be used for parameter of type 'System.Collections.Generic.IEnumerable1[System.Nullable1[System.Int32]]' of method 'Boolean Contains[Nullable1](System.Collections.Generic.IEnumerable1[System.Nullable1[System.Int32]], System.Nullable`1[System.Int32])' (Parameter 'arg0')"

Stack trace: System.Dynamic.Utils.ExpressionUtils.ValidateOneArgument(MethodBase method, ExpressionType nodeKind, Expression arguments, ParameterInfo pi, String methodParamName, String argumentParamName, Int32 index)\r\n at System.Linq.Expressions.Expression.Call(MethodInfo method, Expression arg0, Expression arg1)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.EntityEqualityRewritingExpressionVisitor.VisitContainsMethodCall(MethodCallExpression methodCallExpression)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.EntityEqualityRewritingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)\r\n at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)\r\n at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.EntityEqualityRewritingExpressionVisitor.RewriteAndVisitLambda(LambdaExpression lambda, EntityReferenceExpression source)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.EntityEqualityRewritingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)\r\n at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)\r\n at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.EntityEqualityRewritingExpressionVisitor.Rewrite(Expression expression)\r\n at Microsoft.EntityFrameworkCore.Query.QueryOptimizer.Visit(Expression query)\r\n at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)\r\n at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass12_01.<ExecuteAsync>b__0()\r\n at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func1 compiler)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func1 compiler)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken)\r\n at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable1.GetAsyncEnumerator(CancellationToken cancellationToken)\r\n at System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable1.GetAsyncEnumerator()\r\n at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.<ToListAsync>d__1291.MoveNext()\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\r\n at ConsoleApp3.Program.

d__0.MoveNext()

Steps to reproduce

    public class Blog
    {
        public int Id { get; set; }

        public ICollection<Post> Posts { get; set; }
    }

    public class Post
    {
        public int Id { get; set; }

        public Blog Blog { get; set; }
    }

    public class BloggingContext : DbContext
    {
        public DbSet<Blog> Blog { get; set; }

        public DbSet<Post> Post { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
            => optionsBuilder
                .UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=Test;ConnectRetryCount=0");
    }

    public class Program
    {
        public static async Task Main()
        {
            using (var context = new BloggingContext())
            {
                context.Database.EnsureDeleted();
                context.Database.EnsureCreated();

                var blog1 = new Blog()
                {
                    Posts = new List<Post>() { new Post(), new Post() }
                };

                context.Add(blog1);
                context.SaveChanges();
            }

            using (var context = new BloggingContext())
            {
                var blogs = await context.Blog.ToListAsync();

                var posts = await context.Post
                  .Where(x => blogs.Contains(x.Blog))
                  .ToListAsync();
            }
        }
    }

Further technical details

EF Core version: 3.0.0-preview9.19405.9
Database Provider: Microsoft.EntityFrameworkCore.SqlServer
Operating system: Windows 10
IDE: Visual Studio 2019 16.3.0 Preview 1.0

[ajcvickers]

@roji Is this an entity equality issue?

[roji]

Sorry for missing this, will look into it tomorrow.

[roji]

Repro'd in latest, bug introduced in #16957. Fix on the way.