Using .NET Project File Analyzers on Shared Files

.NET project file analyzers work by linking files to a project (most commonly a *.csproj file) and hooking into Roslyn when that project is built. However, for files that are not linked to any single project, such as solution files, shared configuration files, or repository, this approach doesn’t work.

The .net.csproj file provides a solution: it is a dedicated proxy project that analyzes all such unlinked files in your repository.

How the .net.csproj file Works

The .net.csproj file is a special proxy project that enables analysis of repository-level files. It automatically includes the analyzers automatically detects and analyzes compatible files in the project’s directory tree (such as .csproj, .slnx, .editorconfig, NuGet.config, etc.), along with any files explicitly included.

Placement of the .net.csproj file should be a parent directory common to all projects you want to analyze. In a monorepo this most likely same directory of your solution file, otherwise the root of your repo is the most logical choice.

The .net.csproj file is configured to have no build output and not to automatically include <Compile> items.

.net.csproj includes top level files and as such provides a solid alternative to a Solution items folder.

.net.csproj

A .net.csproj project file looks like this:

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

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference PrivateAssets="all" Include="DotNetProjectFile.Analyzers" Version="1.16.1" />
  </ItemGroup>

</Project>

Download this example .net.csproj

Central Package Management

It is advised to add the reference in the Directory.Build.props file, or Directory.Packages.props when Central Package Management is enabled. In the latter case using a <GlobalPackageReference>:

<ItemGroup Label="Analyzers">
  <GlobalPackageReference Include="DotNetProjectFile.Analyzers" Version="1.15.2" />
</ItemGroup>

In that case the .net.csproj can be as small as this:

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

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
  </PropertyGroup>

</Project>

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