Creating executable assembly at runtime

Question

How can I compile a single code, as a string, into a working and standalone .exe file? I tried three different things:

CSharpCodeProvider: This works fine, but I need it for newer .NET 7 and this solution doesn't work for this version.
CSharpScript: This also works fine, but I need to store the actual generated assembly into a working .exe file on disk.
CSharpCompiler: I think I need this one, however, I can't get it working, I'm still having some problems with references.

Is there a way of actually adding these references automatically? Always, when I add a reference, it will report that an another reference is missing.

Code I'm using, but doesn't work.

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using System.Reflection;

var code = """
    using System;

    // Just a demo program.
    Console.WriteLine("Hello, World!");
    """;

var compilation = CSharpCompilation.Create("DynamicCode")
    .WithOptions(new CSharpCompilationOptions(OutputKind.ConsoleApplication))
    .AddReferences(
        MetadataReference.CreateFromFile(Assembly.Load("System.Private.CoreLib").Location),
        MetadataReference.CreateFromFile(Assembly.Load("System").Location)
    )
    .AddSyntaxTrees(SyntaxFactory.ParseSyntaxTree(code));

// Note: I also tried adding references using the typeof keyword,
// so like typeof(object).Assembly.Location, but that also didn't work.

using var stream = new MemoryStream();
var emitResult = compilation.Emit(stream);

if (emitResult.Success)
{
    var exePath = "DynamicCode.exe";
    File.WriteAllBytes(exePath, stream.ToArray());
    Console.WriteLine($"DynamicCode.exe saved successfully.");
}
else
{
    Console.WriteLine("Failed:");
    foreach (var diagnostic in emitResult.Diagnostics)
    {
        Console.WriteLine(diagnostic);
    }
}

What I got from the output (compile time): (4,1): error CS0103: Console name does not exist in the current context.

When I used following references instead of I used in the code:

var compilation = CSharpCompilation.Create("DynamicCode")
    .WithOptions(new CSharpCompilationOptions(OutputKind.ConsoleApplication))
    .AddReferences(AppDomain.CurrentDomain.GetAssemblies().Select(x => MetadataReference.CreateFromFile(x.Location)))
    .AddSyntaxTrees(SyntaxFactory.ParseSyntaxTree(code));

I'm getting this when running the application, plus the output assembly is something about 3kB, which seems weird to me:

Unhandled Exception: System.IO.FileNotFoundException: Unable to load file or assembly System.Private.CoreLib, Version=7.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e, or one of its dependencies. The system cannot find the specified file.

So am I doing something wrong? Is there a way of automatically adding references, or some "better" way of adding them? I tried things like ChatGPT, but it didn't help me, so I don't know where is the problem.

If the actual solution worked, is there a way of compiling the assembly into .NET Framework v4.7.2? I want to keep the compatibility with older platforms, but my project is coded in .NET 7, so CSharpCodeProvider cannot be used.

ASi · Accepted Answer · 2023-09-13 16:30:24Z

0

Answer to 1 question: To use a console call, you probably need a link to the library System.Console

Answer to question 2: I use something like this to get paths to libraries:

var path = Path.GetDirectoryName(typeof(object).Assembly.Location)!;
var consoleAssemblyPath = Path.Combine(DefaultAssemblysPath, "System.Console.dll");
var rumtimeAssemblyPath = Path.Combine(DefaultAssemblysPath, "System.Runtime.dll");

There seems to be an answer here: https://learn.microsoft.com/en-us/answers/questions/972245/is-it-possible-to-create-a-standalone-console-appl

edited Sep 13, 2023 at 16:30

answered Sep 13, 2023 at 8:40

ASi

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5 Comments

Bird2 Over a year ago

Still doesn't work. It returns a lot of compile-time errors. I added reference to object (typeof(object).Assembly.Location) and it now compiles, however, the generated assembly cannot be ran, runtime error reported: ...Unable to load file or assembly System.Private.CoreLib, Version=7.0.0.0.... It's the same as previously.

ASi Over a year ago

This is quite strange, I have never encountered such an error, there may be a problem with the dll files themselves, try to follow the path where you have installed .net and check for the file you need. I have this way: C:\Program Files\dotnet\shared\Microsoft.NETCore.App\{version}\System.Private.CoreLib.dll

Bird2 Over a year ago

Still the same with added reference

MetadataReference.CreateFromFile(@"C:\Program Files\dotnet\shared\Microsoft.NETCore.App\7.0.10\System.Private.CoreLib.dll")

. Isn't it a .NET bug? It seems too complex for me to create an executable from source code in runtime from .NET 7... still some reference errors.

ASi Over a year ago

Judging by the information from the link I added to the answer: "Unlike classic .net, support of running .net core applications was not added to the Windows O/S. So the compiler only creates dll’s which are run with dotnet or another application."

Bird2 Over a year ago

Oh, so I actually have to run that dll with .NET runtime. Thank you for that information as I though I can actually make a standalone executable.

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