Query: compilation error (dangling qsre) for queries with SelectMany whose selector is a subquery referencing outer qsre

[maumar]

Repro:

    class Program
    {
        static void Main(string[] args)
        {
            using (var ctx = new MyContext())
            {
                ctx.Database.EnsureDeleted();
                ctx.Database.EnsureCreated();
            }

            using (var ctx = new MyContext())
            {
                var query = from c in ctx.Customers
                            from g in (from o in ctx.Orders
                                       where c.Id == o.CustomerId
                                       select new { OwnerName = o.Name, CustomerName = c.Name })
                            select g;

                var result = query.ToList();
            }
        }
    }

    public class Customer
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public List<Order> Orders { get; set; }
    }

    public class Order
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public int CustomerId { get; set; }
    }

    public class MyContext : DbContext
    {
        public DbSet<Customer> Customers { get; set; }
        public DbSet<Order> Orders { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer(@"Server=.;Database=Repro11941;Trusted_Connection=True;MultipleActiveResultSets=True");
        }
    }

QP:

(QueryContext queryContext) => IEnumerable<<>f__AnonymousType0<string, string>> _InterceptExceptions(
    source: IEnumerable<<>f__AnonymousType0<string, string>> _Select(
        source: IEnumerable<TransparentIdentifier<ValueBuffer, <>f__AnonymousType0<string, string>>> _SelectMany(
            source: IEnumerable<ValueBuffer> _ShapedQuery(
                queryContext: queryContext, 
                shaperCommandContext: SelectExpression: 
                    SELECT [c].[Id], [c].[Name]
                    FROM [Customers] AS [c], 
                shaper: ValueBufferShaper), 
            collectionSelector: (ValueBuffer c) => IEnumerable<<>f__AnonymousType0<string, string>> _Select(
                source: IEnumerable<ValueBuffer> _ShapedQuery(
                    queryContext: queryContext, 
                    shaperCommandContext: SelectExpression: 
                        SELECT [t].[OwnerName], [t].[CustomerName]
                        FROM (
                            SELECT [o].[Name] AS [OwnerName], [c].[Name] AS [CustomerName]
                            FROM [Orders] AS [o]
                            WHERE [c].[Id] = [o].[CustomerId]
                        ) AS [t], 
                    shaper: ValueBufferShaper), 
                selector: (ValueBuffer o) => new <>f__AnonymousType0<string, string>(
                    string TryReadValue(o, 0, Order.Name), 
                     ---> [c] <--- .Name
                )), 
            resultSelector: (ValueBuffer c | <>f__AnonymousType0<string, string> g) => TransparentIdentifier<ValueBuffer, <>f__AnonymousType0<string, string>> CreateTransparentIdentifier(
                outer: c, 
                inner: g)), 
        selector: (TransparentIdentifier<ValueBuffer, <>f__AnonymousType0<string, string>> t0) => t0.Inner), 
    contextType: Repro11933.MyContext, 
    logger: DiagnosticsLogger<Query>, 
    queryContext: queryContext)

[maumar]

This is a regression from 2.0.2.

QP in 2.0.2:

(QueryContext queryContext) => IEnumerable<<>f__AnonymousType0<string, string>> _InterceptExceptions(
          source: IEnumerable<<>f__AnonymousType0<string, string>> _ShapedQuery(
              queryContext: queryContext,
              shaperCommandContext: SelectExpression:
                  SELECT [o].[Name] AS [OwnerName], [c].[Name] AS [CustomerName]
                  FROM [Customers] AS [c]
                  CROSS JOIN [Orders] AS [o]
                  WHERE [c].[Id] = [o].[CustomerId],
              shaper: TypedProjectionShaper<TypedCompositeShaper<ValueBufferShaper, ValueBuffer, ValueBufferShaper, ValueBuffer, TransparentIdentifier<ValueBuffer, ValueBuffer>>, TransparentIdentifier<ValueBuffer, ValueBuffer>, <>f__AnonymousType0<string, string>>),
          contextType: EFSampleApp.MyContext,
          logger: DiagnosticsLogger<Query>,
          queryContext: queryContext)

[maumar]

related to #11933

[maumar]

@ajcvickers @divega @smitpatel

[ajcvickers]

@smitpatel Assigned this one to you as a regression in 2.1. It is related to #11933 which @maumar has been investigating. We think that when this is fixed, then it will also fix that issue.

[ajcvickers]

@maumar to look for workarounds.
@smitpatel to fix before 5PM.

[ajcvickers]

@smitpatel / @maumar Can you point to the place (PR, issue, or commit) where we introduced this break?

[maumar]

Workaround:

from c in ctx.Customers
from o in ctx.Orders
where c.Id == o.CustomerId
select new { OwnerName = o.Name, CustomerName = c.Name }

this is essentially what we translated to in 2.0.2

[smitpatel]

@ajcvickers - PR #10647