InvalidProgramException when accessing struct IReadOnlyList<T> in Expression<T>

[chrarnoldus]

Description

The code included below crashes with the following exception:

Unhandled exception. System.InvalidProgramException: Common Language Runtime detected an invalid program.
 at ConsoleApp1.Program.Main(String[] args)

I expected the code to do nothing at all, since I am not even evaluating the IQueryable.

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApp1
{
 internal struct ReadOnlyList<T> : IReadOnlyList<T>
 {
 public int Count
 => throw new Exception();

 public T this[int index]
 => throw new Exception();

 public IEnumerator<T> GetEnumerator()
 {
 throw new Exception();
 }

 IEnumerator IEnumerable.GetEnumerator()
 {
 return GetEnumerator();
 }

 IEnumerator<T> IEnumerable<T>.GetEnumerator()
 {
 return GetEnumerator();
 }
 }

 internal class Program
 {
 private static void Main(string[] args)
 {
 var list = default(ReadOnlyList<string>);
 var unused = Array.Empty<int>()
 .AsQueryable()
 .Select(x => list[x]);
 }
 }
}

Configuration

.NET SDK (reflecting any global.json):
Version: 5.0.100-preview.8.20417.9
Commit: fc62663a35

Runtime Environment:
OS Name: Windows
OS Version: 10.0.19041
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\5.0.100-preview.8.20417.9\

Host (useful for support):
Version: 5.0.0-preview.8.20407.11
Commit: bf45665

Regression?

Yes, compared to 3.1.

Other information

• Replacing the implemented interface IReadOnlyList<T> with IEnumerable<T> resolves the crash.
• Replacing the type argument of ReadOnlyList<string> with a value type resolves the crash.
• Turning the struct ReadOnlyList<T> into a class resolves the crash.
• The code where I originally discovered the issue did not use IQueryable, but a custom method accepting Expression<T>.

Tagging subscribers to this area: @eiriktsarpalis
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[wzchua]

I have narrowed it down to a generic struct implementing an interface being used in an expression

public interface IInterface
{
 string this[int index] { get; }
 string B();
}

public readonly struct GenericStruct<T> : IInterface
{
 public string this[int index]
 => throw new Exception();

 public string B() => "B";
}

internal class Program
{
 private static void Main(string[] args)
 {
 Debugger.Break();
 Expression<Func<GenericStruct<string>, string>> funcE = x => x.B();
 Func<GenericStruct<string>, string> f = funcE.Compile();
 }
}

when you try to break on even on the first line, the debugger doesn't reach the line

[EgorBo]

thrown from https://github.com/dotnet/runtime/blob/master/src/coreclr/src/vm/jitinterface.cpp#L3085

// There is a pathological case where invalid IL refereces __Canon type directly, 
but there is no dictionary availabled to store the lookup.

#38229 ?

[ericstj]

This is a regression from 3.1. Doesn't appear to be specific to collections. CodeGen team, have a look. I reproed on RC1. Could be important for 5.0. cc @jeffschwMSFT @jkotas

[jeffschwMSFT]

@JulieLeeMSFT

[JulieLeeMSFT]

@CarolEidt please take a look.