Microsoft has launched the fifth preview of its planned .NET 10 open source developer platform. The preview release fits C# 14 with user-defined compound assignment operators and enhances the .NET runtime with escape analysis, among other updates.
Announced June 10, .NET 10 Preview 5 can be downloaded from dotnet.microsoft.com. It includes enhancements to features ranging from the runtime and C# 14 to F# 10, NET MAUI, ASP.NET Core, and Blazor.
C# 14 type authors can now implement compound assignment operators in a user-defined manner that modifies the target in place rather than creating copies. Pre-existing code is unchanged and works the same as before. Meanwhile, in the .NET runtime, the JIT compiler’s escape analysis implementation has been extended to model delegate invokes. When compiling source code to IL (intermediate language), each delegate is transformed into a closure class with a method corresponding to the delegate’s definition and fields matching any captured variables. At runtime, a closure object is created to instantiate the captured variables along with a Func object to invoke the delegate. This runtime preview also enhances the JIT’s inlining policy to take better advantage of profile data. Additionally, F# 10 introduces scoped warning controls with a new #warnon directive supporting fine-grained control over compiler diagnostics.
