Unity C# Patch

Unleash the full potential by being in sync with the latest C# versions that are configured individually for each .asmdef.

How it works:

1. Editor Patching: The UnityEditorPatch is responsible for updating the built-in dotnet SDK within the Unity editor. Unity, by default, ships with dotnet version 6.0.21.

2. Language Version Tracking: UnityPackage keeps track of the C# language version specified in your csc.rsp file that is located alongside each .asmdef. This is required to help Unity to understand which C# version it should use while compiling the code of your .asmdef.

3. Project File Adjustment: Finally, UnityPackage modifies the .csproj file to reflect the C# version specified in the csc.rsp. This alerts your IDE to the correct language version to use, ensuring it can provide you with all the relevant language features.

Supported AssemblyDefinition locations:

1. Project - everything that is located in Assets/ folder of your project.
2. Embedded Packages - everything that is located in Packages/ folder of your project.
3. Local Packages - everything that is located anywhere on your pc with specified path with file: prefix in manifest.

Warning

DON'T put .asmdef with its csc.rsp at the root of the project (Assets/). Unity in that case will apply the specified C# version to everything, that may cause compile errors (e.g. field keyword is used as a name in some third party library). Place it in any subfolder (usually Scripts, but doesn't matter, just not at the root)

Note

OS support: Mac / Linux / Windows. You can backup your editor just in case, but should be fine.

Patch will modify the Editor installation, so all the projects that are using it will be affected (default for unity C# version will be used for compilation, but from newer (patched) dotnet sdk)

Tested on target platforms: Mac / Windows / Linux / iOS / Android / WebGL

Tested in IDEs:

Rider 2025.1 with integration package [email protected]

VSCode 1.99.3 with integration package [email protected]

Visual Studio Community 2022 17.13.6 with integration package [email protected]

How to Install:

1. Add the package via git url https://github.com/kandreyc/unity-csharp-patch.git#v1.4.0
2. Ensure Unity Editor is closed.
3. Ensure latest dotnet sdk is installed. Download Page
4. Open terminal at folder EditorPatch~ inside the added package.
5. Patch the editor (administrative privileges are required):

$ dotnet UnityEditorPatch.dll apply --editor '/Applications/Unity/Hub/Editor/2022.3.21f1' --allow-prerelease

where --editor - path to the unity editor

where --allow-prerelease - (optional) allows to use prerelease dotnet sdk

In case if you want to revert the patch:

$ dotnet UnityEditorPatch.dll revert --editor '/Applications/Unity/Hub/Editor/2022.3.21f1'

where --editor - path to the unity editor

6. Open the Unity Editor with your project and create a csc.rsp file alongside desired .asmdef with the following content:

-langVersion:13
-nullable:enable

where:

• langVersion (optional) - C# version you want to be used for this .asmdef. Values are 10, 11, 12, 13, preview
• nullable (optional) - allows to use nullables like string? without defining #nullable enable/disable in each file where it used. Values are enable, disable

7. Refresh the Editor. All required magic should be done here.
8. Enjoy!

Language Support

Note

preview features support of .net 10 in Rider / Visual Studio is still in development. Code will compile and work, but you may suffer from errors in IDE. Currently only VSCode supports all new features

C#	Feature	Support
preview	field keyword	Yes
preview	partial events and instance constructors	Yes
preview	nameof unbound generic types support for	Yes
preview	Extension members	Yes
preview	Null conditional assignment	Yes
preview	Simple lambda parameters	Yes
preview	Implicit span conversions	Yes
13	params collections	Yes
13	New lock type and semantics	No
13	New escape sequence - \e	Yes
13	Method group natural type improvements	Yes
13	Implicit indexer access in object initializers	Yes
13	Enable ref locals and unsafe contexts in iterators and async methods	Yes
13	Enable ref struct types to implement interfaces	No
13	Allow ref struct types as arguments for type parameters in generics	No
13	Partial properties and indexers	Yes
13	Overload resolution priority	PolySharp
12	Primary constructors	Yes
12	Optional parameters in lambda expressions	Yes
12	Alias for any type	Yes
12	Inline arrays	No
12	Collection expressions	Yes
12	Interceptors	No
11	Raw string literals	Yes
11	static abstract/static virtual members in interfaces	No
11	Checked user defined operators	Yes
11	Relaxed shift operators	Yes
11	Unsigned right-shift operator	Yes
11	Generic attributes	Crash
11	UTF-8 string literals	Yes
11	Newlines in string interpolations	Yes
11	List patterns	Yes
11	File-local types	Yes
11	Required members	PolySharp
11	Auto-default structs	Yes
11	Pattern match Span<char> or ReadOnlySpan<char> on a constant string	Yes
11	Extended nameof scope	Yes
11	Numeric IntPtr and UIntPtr	Yes
11	ref fields	No
11	ref scoped variables	PolySharp
11	Improved method group conversion to delegate	Yes
10	Record structs	Yes
10	Improvements of structure types	Yes
10	Interpolated string handler	PolySharp
10	Global using directives	Yes
10	File-scoped namespace declaration	Yes
10	Extended property patterns	Yes
10	Lambda expression improvements	Yes
10	Constant interpolated strings	Yes
10	Record types can seal ToString	Yes
10	Assignment and declaration in same deconstruction	Yes
10	Improved definite assignment	Yes
10	CallerArgumentExpression attribute	PolySharp
10	Enhanced #line pragma	Yes

Support:

• Yes - feature works exactly as expected.
• No - requires runtime features or BCL changes that Unity does not have. Attempting to use the feature may result in compiler errors.
• Crash - requires runtime features that Unity does not have. Attempting to use the feature may compile, but will result in crashes.
• PolySharp - feature works when using PolySharp and/or manually implementing missing APIs.

Motivation

This project was inspired and motivated by two key repositories:

1. CsprojModifier
2. UnityRoslynUpdater

While the UnityRoslynUpdater serves its purpose by upgrading the C# version across all projects, my goal was to allow using custom C# version only where it is required. So that my package gives the control of what assemblies should be allowed to use newer C# version, which helps to prevent naming conflicts with embedded/thirdparty libs/sdks, or affect the projects that you don't want to

Inspired by CsprojModifier, I've automated modifying .csproj files based on .asmdef properties, making it possible for your IDE to use the newest C# features.