Stuff like Roslyn analysers, code generators and interceptors, only take C# semantics into account, the first one also works with VB.NET.
Since its introduction that CLR has the notion of CLS, the Common Language Subset, that any language targeting the CLR should be able to understand.
Anything in the MSIL or metadata, that isn't part of that, requires additional effort from the respective language to be able to expose those features, and many of the more recent improvements, are more in the sense of CLR meaning C# Language Runtime, than Common Language Runtime.
Since its introduction that CLR has the notion of CLS, the Common Language Subset, that any language targeting the CLR should be able to understand.
Anything in the MSIL or metadata, that isn't part of that, requires additional effort from the respective language to be able to expose those features, and many of the more recent improvements, are more in the sense of CLR meaning C# Language Runtime, than Common Language Runtime.