JetBrains Rider 2018.3 fully supports all C# versions up to C# 6.0 and partially C# 7.0. C# is the primary programming language JetBrains Rider is intended for, and therefore all JetBrains Rider features (excluding some features specific to other languages) are supported in C#.
By default, JetBrains Rider automatically detects C# version based on the associated compiler. However, you can specify the target C# version explicitly — press Alt+Enter on the project in the Solution Explorer and use the Language version selector on the Application page of the Project Properties dialog.
Depending on the current C# version — whether it is detected automatically or set explicitly — JetBrains Rider adjusts its features. For example, code inspection detects places in your code, which could be simplified using new language features.
Information on JetBrains Rider features in C# is available in the following sections: