MethodAccessException on equality comparison of a record with private fields

[iminashi]

Equality comparison of a record type with private fields no longer works in SDK 8.0.400 for a type that is in a different assembly.

Repro steps

Assembly A:

Record type with private fields.

module Types

type Value =
    private { value: uint32 }

    static member Zero = { value = 0u }
    static member Create(value: int) = { value = uint value }

Assembly B:

Anything that uses the = operator on the type.

module Test

open NUnit.Framework
open Types

[<Test>]
let Equality () =
    let zero = Value.Create 0

    Assert.That(Value.Zero = zero, "zero equals zero")

Expected behavior

Equality comparison works.

Actual behavior

Runtime exception:

System.MethodAccessException : Attempt by method 'Test.Equality()' to access method 'Types+Value.Equals(Value, System.Collections.IEqualityComparer)' failed.

Known workarounds

• Remove the private modifier.
• Replace = with Equals call.

Related information

• .NET SDK 8.0.400-preview.0.24324.5

[vzarytovskii]

Likely caused by #16857 (or by realsig, or by mixture of both)

[vzarytovskii]

Method is generated as internal for some reason:

[vzarytovskii]

@iminashi I suppose itermediate workaroud would be to add IVT attribute to the first assembly (the one which test is using), until we implement a fix.

[psfinaki]

Yes, the above helps (putting InternalsVisibleTo).

[iminashi]

I was just trying out the VS preview version (to see if it had the fix for #17161) when I ran into this, so this does not really affect me that much for now.

[psfinaki]

Note, --realsig+ also seems to fix the issue.