SlnMerge

SlnMerge merges the solutions when creating solution file by Unity Editor.

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Table of Contents

• Works with
• How to use
  • 1. Install SlnMerge
  • 2. Create ProjectName.sln.mergesettings and configure a target solution.
• Settings
  • Add projects to solution folders
• Troubleshooting
  • Always regenerate the solution file, and Visual Studio displays a conflict dialog.
• License

Works with

• Unity 2022.3+
• Windows 11 and macOS 10.15
• Microsoft Visual Studio 2022/2026
• JetBrains Rider 2025.x

Both legacy solution format (.sln) and modern solution format (.slnx) are supported.

How to use

1. Install SlnMerge

You can use Package Manager to install a package via git.

https://github.com/Cysharp/SlnMerge.git?path=src

2. Create ProjectName.sln.mergesettings and configure a target solution.

Create a setting XML file named <ProjectName>.sln.mergesettings.

For example, when the project name is MyUnityApp, Unity Editor generates MyUnityApp.sln. You need to create MyUnityApp.sln.mergesettings.

Note

If you are using .slnx format, please read .sln as .slnx below. Solution files can only be merged in the same format. SlnMerge cannot merge .slnx file into .sln file.

<SlnMergeSettings>
    <MergeTargetSolution>..\MyUnityApp.Server.sln</MergeTargetSolution>
</SlnMergeSettings>

You can specify the target solution to merge by MergeTargetSolution element.

NOTE: If you don't have the settings, SlnMerge uses ProjectName.Merge.sln as a target.

Settings

The mergesettings file has the following settings:

• Disabled: Disable SlnMerge (default: false)
• MergeTargetSolution: Path of the solution you want to merge
• NestedProjects: Specify the projects to nest. Usually used as a solution folder
  • NestedProject/FolderPath: Folder path on solution (created if it doesn't exist; mutally exclusive with FolderGuid)
  • NestedProject/FolderGuid: GUID of folder on solution (mutally exclusive with FolderPath)
  • NestedProject/ProjectName: Project name (mutally exclusive with ProjectGuid)
    • Wildcard is available (?, *)
  • NestedProject/ProjectGuid: Project GUID (mutally exclusive with ProjectName)
• ProjectConflictResolution: Processing strategy when a solution contains a project with the same name (PreserveAll, PreserveUnity, PreserveOverlay)
  • PreserveAll: Preserve all projects (both Unity generated projects and original projects)
  • PreserveUnity: Preserve Unity generated projects. (discard original project in a overlay solution)
  • PreserveOverlay: Preserve original projects in a overlay solution. (discard Unity generated projects from a merged solution)

Add projects to solution folders

You can use NestedProjects settings to move projects to solution folders. When a solution folder doesn't exist, SlnMerge will add the solution folder to the solution automatically. But, you need to define a solution folder as SolutionFolder in mergesettings.

<SlnMergeSettings>
    <MergeTargetSolution>..\ChatApp.Server.sln</MergeTargetSolution>
    <SolutionFolders>
        <!-- Define a solution folder named 'Unity' with GUID -->
        <SolutionFolder FolderPath="Unity" Guid="{55739033-89BA-48AE-B482-843AFD452468}"/>
    </SolutionFolders>
    <NestedProjects>
        <NestedProject ProjectName="Assembly-CSharp" FolderPath="Unity" />
        <NestedProject ProjectName="Assembly-CSharp-Editor" FolderPath="Unity" />
    </NestedProjects>
</SlnMergeSettings>

Troubleshooting

Always regenerate the solution file, and Visual Studio displays a conflict dialog.

1. Close Unity Editor.
2. Delete .csproj and .sln are generated by Unity Editor.
3. Reopen the project in Unity Editor

If a merge target solution has a project with the same name in the Unity generated solution, you can use use ProjectConflictResolution option to fix the conflict in a 3-way.

1. Preserve all projects (by default)
2. Preserve the project in the merge target solution
3. Preserve the project in the Unity generated solution

License

MIT License