ILAsm.Managed

Portable managed Mono CIL assembler.

Package name	nuget.org
ilasm-cli
ILAsm.Managed
ILAsm.Managed.Core

---

What is this?

Mono CIL assembler exactly ported to .NET, .NET Core and .NET Frameworks.

Target platforms:

• .NET 8.0, 7.0, 6.0 and 5.0
• .NET Core 3.1 and 2.2
• .NET Standard 2.1 and 2.0
• .NET Framework 4.8, 4.6.1, 4.5, 4.0, 3.5 and 2.0

There are two packages for this project, which can be used for different purposes:

• ilasm-cli: Contains ported Mono ilasm executable (dotnet CLI interface).
• ILAsm.Managed: Contains ported Mono ilasm executable (MSBuild scripting).
• ILAsm.Managed.Core: Pure library for ported Mono ilasm.

---

ilasm-cli

ilasm-cli package suppors dotnet CLI interface. Try simply installation when you want to get ILAsm on the cli as follows:

C:\>dotnet tool install -g ilasm-cli
You can invoke the tool using the following command: ilasm
Tool 'ilasm-cli' (version '1.1.0') was successfully installed.

C:\>ilasm
Mono IL assembler compiler
ilasm [options] source-files
   --about            About the Mono IL assembler compiler
   --version          Print the version number of the compiler
   /output:file_name  Specifies output file.
   /exe               Compile to executable.
   /dll               Compile to library.
   /debug             Include debug information.
   /key:keyfile       Strongname using the specified key file
   /key:@container    Strongname using the specified key container
   /noautoinherit     Disable inheriting from System.Object by default
Options can be of the form -option or /option

---

ILAsm.Managed

You can refer to MSBuild symbols as properties with ILAsm.Managed package. Using this property, you can easily run the command in safer multi-platform environment:

<!-- Execute Mono ilasm CLI -->
<Exec Command="$(ILAsmManagedBuildToolingRuntimeName)&quot;$(ILAsmManagedBuildToolingPath)&quot; ...." />

---

ILAsm.Managed.Core

This package contains up to just before the Main entry point. It can be used directly in MSBuild custom tasks or when incorporating ILAsm into your own implementation. However, since the original implementation is made into a library as is, it may not be easy to handle.

The CLI entry point can be accomplished with a single line as follows:

namespace Mono.ILASM;

public static class Program
{
    public static int Main(string[] args) =>
        Driver.Main(args);
}

---

Background

This is a further derivative project of IL2C and ILCompose. In fact, the original authors are to be commended, as they simply ported the Mono ilasm artifact to a modern environment.

Currently (.NET 6), Microsoft's CoreCLR team is working on a port of the .NET Framework's ILAsm, Microsoft.NETCore.ILAsm and a set of derivative packages. These include native binaries, i.e., binaries specific to Windows and Linux (different for each distribution).

There are SDK scripts for IL that reference these packages from the <PackageReference> tag. However, there is a fatal problem with this method. Commands such as dotnet restore and nuget restore do not evaluate the MSBuild scripts when resolving package references. Therefore, this package reference actually fails and the build always fails.

No, if you build from Visual Studio, you can build. So I finally discovered this problem by failing to build with GitHub Actions. I thought of various solutions, but in the end, as long as ILAsm is native code, it is difficult (at least to an outsider) to fundamentally solve this problem.

So we looked into Mono's ILAsm and found that it was fully managed code, albeit clunky, so we decided to port it.

---

License

Under MIT excepts original Mono source code, see Mono License.

---

History

• 1.2.0:
  • Supported .NET 8.0 SDK.
• 1.1.9:
  • Supported .NET 8.0 RC2.
• 1.1.0:
  • Supported dotnet CLI installation.
• 1.0.0:
  • Initial release.