MixedIL.Fody

This is an add-in for Fody which allows you to impliment C# method by IL code.

• Installation
• Usage
• Example
• Comparison with InlineIL.Fody

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Installation

• Include the Fody and MixedIL.Fody NuGet packages with a PrivateAssets="all" attribute on their <PackageReference /> items. Installing Fody explicitly is needed to enable weaving.

  <PackageReference Include="Fody" Version="..." PrivateAssets="all" />
  <PackageReference Include="MixedIL.Fody" Version="..." PrivateAssets="all" />

• If you already have a FodyWeavers.xml file in the root directory of your project, add the <MixedIL /> tag there. This file will be created on the first build if it doesn't exist:

  <?xml version="1.0" encoding="utf-8" ?>
  <Weavers>
    <MixedIL />
  </Weavers>

  See Fody usage for general guidelines, and Fody Configuration for additional options.

---

Usage

1. Write a method stub in a C# project with keyword extern and an attribute provided in MixedIL called MixedILAttribute

using MixedIL;

namespace System;

public class ObjectHelper
{
    [MixedIL]
    public static extern bool AreSame<T>(ref T a, ref T b);
}

2. Then create a .il file in the the C# project and implement the method in il code. C# dll

.class public abstract auto ansi sealed beforefieldinit System.ObjectHelper
{
    .method public hidebysig static bool AreSame<T>(!!T& a, !!T& b) cil managed aggressiveinlining
    {
        .maxstack 2
        ldarg.0
        ldarg.1
        ceq
        ret
    }
}

3. Compile the project and that's it.

NOTE:

• The method signature and declaring type should be the same.
• Only il method body will be injected into the assembly file, other parts like attributes in il code won't. You can just write all the other parts using C# code.

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Options

Options that can be configured through some MSBuild properties to set in consuming projects.

• MixedILExcludeIgnoresAccessChecksToAttribute: Exclude IgnoresAccessChecksToAttribute from source files to comiple.

NOTE:

• IgnoresAccessChecksToAttribute is used to access non-public types and members across assemblies through IL code. It is helpful when you are using MixedIL or System.Reflection.Emit.

---

Examples

• An example project
• A reimplementation of the System.Runtime.CompilerServices.Unsafe called MixedIL.Unsafe is provided as an example.

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Comparison with InlineIL.Fody

InlineIL.Fody is a remarkable fody add-in which lets you inject IL instructions by calling normal static C# methods. While there are some differences, so you can choose based on your requirement.

• Basically, in most cases you can use InlineIL, which is more friendly to C# developers.
• MixedIL is more flexible and less restrictive, since pure IL code will be written.
  For instance, you can invoke backing field of a property without setter by pure IL, like this:
  stfld string [System.Runtime]System.Reflection.AssemblyKeyNameAttribute::'<KeyName>k__BackingField'
  see example code.
  However, up to now, you will get compile error if you would like to implement it using InlineIL.