Where can I submit request for new features in the C# language?

GitHub Issues:

• C# language
• VB language
• C# cross cutting VB
• Roslyn discussions on the Rosyln compiler (only)
• CoreFX This includes things like System.Collections, System.IO for .NET Core (.NET Core 2.0)
• CoreCLR This covers RyuJIT, GC and mscorlib for .NET Core (.NET Core 2.0)
• ASP.NET Core This is for ASP.NET Core (.NET Core 2.0)
• ASP.NET 4.7 – unknown

Historical places not for current discussion:

• Roslyn C# Language Design forum
• Roslyn discussions on C# 6.0, C# 7.0 and beyond

There is also the Visual Studio Uservoice for requests pertaining to Visual Studio specifically