Uuid Interop

CoreLibInternal.cs

using System.Diagnostics.CodeAnalysis;
using System.Runtime.CompilerServices;

[assembly:IgnoresAccessChecksTo("System.Private.CoreLib")]

namespace Uuid.CoreLib
{
    public static class Internal
    {
        public static unsafe void GetRandomBytes(byte* buffer, int length)
        {
            Interop.GetRandomBytes(buffer, length);
        }
    }
}

// ReSharper disable once CheckNamespace
namespace System.Runtime.CompilerServices
{
    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]
    [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
    [SuppressMessage("ReSharper", "UnusedAutoPropertyAccessor.Global")]
    public class IgnoresAccessChecksToAttribute : Attribute
    {
        public IgnoresAccessChecksToAttribute(string assemblyName)
        {
            AssemblyName = assemblyName;
        }

        public string AssemblyName { get; }
    }
}

Program.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;

namespace Uuid.Interop.Compile
{
    class Program
    {
        static void Main(string[] args)
        {
            var metadataReferences = new[]
                {
                    Assembly.Load(new AssemblyName("System.Runtime")),
                    Assembly.Load(new AssemblyName("System.Private.CoreLib"))
                }
                .Select(x => MetadataReference.CreateFromFile(x.Location))
                .ToList();


            var compilationOptions = new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary)
                .WithMetadataImportOptions(MetadataImportOptions.Internal)
                .WithOptimizationLevel(OptimizationLevel.Release)
                .WithAllowUnsafe(true);

            var topLevelBinderFlagsProperty = typeof(CSharpCompilationOptions)
                .GetProperty("TopLevelBinderFlags", BindingFlags.Instance | BindingFlags.NonPublic);
            if (topLevelBinderFlagsProperty == null)
                throw new Exception("Could not find TopLevelBinderFlags");
            topLevelBinderFlagsProperty.SetValue(compilationOptions, (uint) 1 << 22);

            var code = GetInteropCode();

            var compilation = CSharpCompilation.Create(
                "Uuid.CoreLib",
                new[]
                {
                    CSharpSyntaxTree.ParseText(code)
                },
                metadataReferences,
                compilationOptions);

            using (var ms = new MemoryStream())
            {
                var compilationResult = compilation.Emit(ms);
                if (!compilationResult.Success)
                {
                    throw new Exception(string.Join("\n", compilationResult.Diagnostics));
                }

                ms.Seek(0, SeekOrigin.Begin);
                var assemblyBytes = ms.ToArray();
                var output = Path.Combine(Directory.GetCurrentDirectory(), "Uuid.CoreLib.dll");
                File.WriteAllBytes(output, assemblyBytes);
                Console.WriteLine($"path to dll: {output}");
            }
        }

        private static string GetInteropCode()
        {
            using var stream =
                typeof(Program).Assembly.GetManifestResourceStream("Uuid.Interop.Compile.CoreLibInternal.cs");
            if (stream == null)
                throw new Exception("Could not find embedded resource that contains interop source code.");
            using var reader = new StreamReader(stream, Encoding.UTF8);
            return reader.ReadToEnd();
        }
    }
}

Uuid.Interop.Compile.csproj

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

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>netcoreapp3.1</TargetFramework>
        <OutputType>Exe</OutputType>
        <LangVersion>8.0</LangVersion>
        <Nullable>enable</Nullable>
        <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
    </PropertyGroup>
    
    <ItemGroup>
      <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.4.0" />
      <PackageReference Include="System.Runtime" Version="4.3.1" />
    </ItemGroup>
    
    <ItemGroup>
      <Compile Remove="CoreLibInternal.cs" />
      <EmbeddedResource Include="CoreLibInternal.cs" />
    </ItemGroup>

</Project>