IgnoreAccessibilitySample

FodyWeavers.xml

<?xml version="1.0" encoding="utf-8"?>
<Weavers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="FodyWeavers.xsd">
  <InlineIL />
</Weavers>

IgnoreAccessChecksToAttribute.cs

namespace System.Runtime.CompilerServices
{
    public class IgnoresAccessChecksToAttribute : Attribute
    {
        public IgnoresAccessChecksToAttribute(string assemblyName)
        {
            AssemblyName = assemblyName;
        }

        public string AssemblyName { get; }
    }
}

IgnoreAccessibilitySample.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net7.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Fody" Version="6.6.4"  PrivateAssets="all" />
    <PackageReference Include="InlineIL.Fody" Version="1.7.2" PrivateAssets="all" />
  </ItemGroup>

</Project>

Program.cs

using InlineIL;
using static InlineIL.IL.Emit;

// Ignore runtime access checks to itself
[assembly: System.Runtime.CompilerServices.IgnoresAccessChecksTo("IgnoreAccessibilitySample")]

Console.WriteLine(GetPrivateFieldFromUserDefinedType(new UserDefinedType(false)));
Console.WriteLine(GetPrivateFieldFromUserDefinedType(new UserDefinedType(true)));

static bool GetPrivateFieldFromUserDefinedType(UserDefinedType u)
{
   Ldarg_0();
   Ldfld(new FieldRef(typeof(UserDefinedType), "_privateField"));
   return IL.Return<bool>();
}

// ----------------

class UserDefinedType
{
    bool _privateField;

    public UserDefinedType(bool v)
    {
        _privateField = v;
    }
}