Notice

As of MSBuild 15.8, RoslynCodeTaskFactory is now built in. For more information, please read the official documentation. To report issues with the built-in RoslynCodeTaskFactory, please visit https://github.com/Microsoft/msbuild/issues/new.

You will only need to this library if you're using an older version of MSBuild.

Roslyn CodeTaskFactory

An MSBuild TaskFactory that uses the Roslyn compiler to generate .NET Standard task libraries which can be used by inline tasks. It is a replacement of the built in CodeTaskFactory which uses CodeDom and does not work in .NET Core.

Getting Started

To get started, add a PackageReference to the RoslynCodeTaskFactory package.

NuGet Package Manager UI

Search for RoslynCodeTaskFactory

NuGet Package Manager Console

Install-Package RoslynCodeTaskFactory

DotNet CLI

dotnet add package RoslynCodeTaskFactory

The package sets an MSBuild property named $(RoslynCodeTaskFactory) which should be used in a <UsingTask />. The RoslynCodeTaskFactory is implemented exactly like the stock MSBuild CodeTaskFactory with the only difference being which AssemblyFile to use.

This example is the same as the one from MSDN with only the AssemblyFile attribute changed to use the RoslynCodeTaskFactory:

<Project ToolsVersion="12.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">  
  <!-- This simple inline task does nothing. -->  
  <UsingTask  
    TaskName="DoNothing"  
    TaskFactory="CodeTaskFactory"  
    AssemblyFile="$(RoslynCodeTaskFactory)"
    Condition=" '$(RoslynCodeTaskFactory)' != '' ">
    <ParameterGroup />  
    <Task>  
      <Reference Include="" />  
      <Using Namespace="" />  
      <Code Type="Fragment" Language="cs">  
      </Code>  
    </Task>  
  </UsingTask>  
</Project>  

Hello World

Here is a more robust inline task. The HelloWorld task displays "Hello, world!" on the default error logging device, which is typically the system console or the Visual Studio Output window.

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">  
  <!-- This simple inline task displays "Hello, world!" -->  
  <UsingTask  
    TaskName="HelloWorld"
    TaskFactory="CodeTaskFactory"
    AssemblyFile="$(RoslynCodeTaskFactory)"
    Condition=" '$(RoslynCodeTaskFactory)' != '' ">
    <ParameterGroup />  
    <Task>  
      <Using Namespace="System"/>  
      <Using Namespace="System.IO"/>  
      <Code Type="Fragment" Language="cs">  
<![CDATA[  
// Display "Hello, world!"  
Log.LogError("Hello, world!");  
]]>  
      </Code>  
    </Task>  
  </UsingTask>  
</Project>  

You could save the HelloWorld task in a file that is named HelloWorld.targets, and then invoke it from a project as follows.

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">  
  <Import Project="HelloWorld.targets" />  
  <Target Name="Hello">  
    <HelloWorld />  
  </Target>  
</Project>  

Samples

Open Samples.sln to see more samples of the inline task in a .NET Framework and .NET Standard project.