SelectMany with inline array values over Where crashes ExpressionTreeFuncletizer with InvalidOperationException

[aromaa]

Bug description

Using SelectMany with an inline array followed by Select that's used to project Where over the entities causes the ExpressionTreeFuncletizer to crash with an InvalidOperationException.

Your code

#:property TargetFramework=net10.0
#:property PublishAot=false
#:package Npgsql.EntityFrameworkCore.PostgreSQL@10.0.1

using Microsoft.EntityFrameworkCore;

TestDbContext test = new();
_ = test.Entities.SelectMany(e => new[] { "a", "b" }.Select(k => new { k, a = e })).GroupBy(a => a.k).ToList();

class TestDbContext : DbContext
{
    public DbSet<TestEntity> Entities => this.Set<TestEntity>();

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) =>
        optionsBuilder.UseNpgsql();
}

record TestEntity(int Id, string Value);

Stack traces

Unhandled exception. System.InvalidOperationException: An exception was thrown while attempting to evaluate a LINQ query parameter expression. See the inner exception for more information. To show additional information call 'DbContextOptionsBuilder.EnableSensitiveDataLogging'.
 ---> System.InvalidOperationException: unbound variable: k
   at System.Linq.Expressions.Interpreter.LightCompiler.EnsureAvailableForClosure(ParameterExpression expr)
   at System.Linq.Expressions.Interpreter.LightCompiler.ResolveLocal(ParameterExpression variable)
   at System.Linq.Expressions.Interpreter.LightCompiler.LoadLocalNoValueTypeCopy(ParameterExpression variable)
   at System.Linq.Expressions.Interpreter.LightCompiler.CompileGetVariable(ParameterExpression variable)
   at System.Linq.Expressions.Interpreter.LightCompiler.Compile(Expression expr)
   at System.Linq.Expressions.Interpreter.LightCompiler.CompileConvertUnaryExpression(Expression expr)
   at System.Linq.Expressions.Interpreter.LightCompiler.Compile(Expression expr)
   at System.Linq.Expressions.Interpreter.LightCompiler.CompileTop(LambdaExpression node)
   at System.Linq.Expressions.Expression`1.Compile(Boolean preferInterpretation)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.<Evaluate>g__EvaluateCore|71_0(Expression expression, Boolean& evaluateAsParameter, String& parameterName, Boolean& isContextAccessor)
   --- End of inner exception stack trace ---
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.<Evaluate>g__EvaluateCore|71_0(Expression expression, Boolean& evaluateAsParameter, String& parameterName, Boolean& isContextAccessor)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Evaluate(Expression expression, Boolean& evaluateAsParameter, String& parameterName, Boolean& isContextAccessor)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.ProcessEvaluatableRoot(Expression evaluatableRoot, State& state, Boolean forceEvaluation)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitBinary(BinaryExpression binary)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression, State& state)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitLambda[T](Expression`1 lambda)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression, State& state)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitUnary(UnaryExpression unary)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit[T](ReadOnlyCollection`1 expressions, Func`2 elementVisitor, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(ReadOnlyCollection`1 expressions, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitMethodCall(MethodCallExpression methodCall)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit[T](ReadOnlyCollection`1 expressions, Func`2 elementVisitor, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(ReadOnlyCollection`1 expressions, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitMethodCall(MethodCallExpression methodCall)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit[T](ReadOnlyCollection`1 expressions, Func`2 elementVisitor, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(ReadOnlyCollection`1 expressions, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitNew(NewExpression new)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression, State& state)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitLambda[T](Expression`1 lambda)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit[T](ReadOnlyCollection`1 expressions, Func`2 elementVisitor, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(ReadOnlyCollection`1 expressions, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitMethodCall(MethodCallExpression methodCall)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression, State& state)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitLambda[T](Expression`1 lambda)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression, State& state)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitUnary(UnaryExpression unary)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit[T](ReadOnlyCollection`1 expressions, Func`2 elementVisitor, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(ReadOnlyCollection`1 expressions, StateType& aggregateStateType, State[]& expressionStates, Boolean poolExpressionStates)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.VisitMethodCall(MethodCallExpression methodCall)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.Visit(Expression expression, State& state)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.ExtractParameters(Expression expression, Dictionary`2 parameters, Boolean parameterize, Boolean clearParameterizedValues, Boolean precompiledQuery)
   at Microsoft.EntityFrameworkCore.Query.Internal.ExpressionTreeFuncletizer.ExtractParameters(Expression expression, Dictionary`2 parameters, Boolean parameterize, Boolean clearParameterizedValues)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExtractParameters(Expression query, Dictionary`2 parameters, IDiagnosticsLogger`1 logger, Boolean compiledQuery, Boolean generateContextAccessors)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteCore[TResult](Expression query, Boolean async, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.GetEnumerator()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Program.<Main>$(String[] args)

Verbose output

EF Core version

10.0.4

Database provider

Npgsql.EntityFrameworkCore.PostgreSQL

Target framework

.NET 10

Operating system

Windows 11

IDE

No response

[roji]

AI Triage

The below is an AI-generated analysis and may contain inaccuracies.

Confirmed as a bug. This is in area-query and is not provider-specific: the exception happens during funcletization before SQL generation, and I was able to reproduce it with Microsoft.EntityFrameworkCore.Sqlite 10.0.4 as well.

System.InvalidOperationException: An exception was thrown while attempting to evaluate the LINQ query parameter expression 'k'. See the inner exception for more information.
 ---> System.InvalidOperationException: unbound variable: k

I also checked older versions:

• Reproduces on EF Core 10.0.3.
• Reproduces on EF Core 9.0.11.

So this does not appear to be a regression introduced in 10.0.4.

Possible related issues:

• SelectMany with inline array values crashes SQL generator with NullReferenceException #38285 is related to SelectMany over inline array values, but its repro discards the inline-array range variable (Select(k => e)). The key difference here is projecting k (Select(k => new { k, e })), which triggers the funcletizer unbound variable failure before SQL generation. If k is not projected, the query gets past funcletization and fails later in the pipeline instead, so this still seems to be distinct from SelectMany with inline array values crashes SQL generator with NullReferenceException #38285.
• [Regression] Unexpected unbound variable error #37045 is a related open funcletizer unbound variable issue, but it has a different query shape.
• EF9: Unbound variable error when combining db and non-db condition #34883 and [Regression] Unexpected unbound variable error with closure #35152 are closed unbound variable funcletizer issues with different shapes.

minimal repro

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

await using var context = new TestContext();

_ = context.Entities
    .SelectMany(e => new[] { "a" }.Select(k => new { k, e }))
    .ToList();

public class TestContext : DbContext
{
    public DbSet<TestEntity> Entities => Set<TestEntity>();

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder
            .UseSqlite("Data Source=:memory:")
            .LogTo(Console.WriteLine, LogLevel.Information)
            .EnableSensitiveDataLogging();
}

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