With this latest preview, runtime-async — the runtime’s built-in implementation of async/await — continues to close the gap with the compiler-generated state-machine model, according to Microsoft. Async versions of methods are now compiled through the tiered compilation pipeline. Async methods previously bypassed tiering and always ran the tier0 code, which was optimized for compilation speed rather than steady-state throughput.
On the WebAssembly front, .NET 11 is bringing CoreCLR to WebAssembly with a portable interpreter-plus-R2R (ReadyToRun) model that reuses RyuJIT for ahead-of-time code generation. This configuration could start up in Preview 6, and now runs the CoreCLR libraries test suite end-to-end in Preview 7.
Preview 7 also brings C# language and compiler updates including labeled break and continue. With C# 15, break and continue can name an enclosing loop or switch, allowing developers to exit or continue an outer construct directly from an inner one without threading state through a flag or resorting to goto. Also with C# 15, union types use the Try-Both matching approach. When a pattern is applied to a union value, the compiler first tests the pattern against the union instance itself; if that test fails, it tests the pattern against the union’s contained Value.
