.NET 10 Preview 6 brings JIT improvements, one-shot tool execution

A newly arrived sixth preview of Microsoft’s planned.NET 10 application development platform touts improved JIT code generation for struct arguments, one-shot tool execution, and other enhancements in the.NET libraries, runtime, and SDK, as well as the ASP.NET Core, Blazor, and.NET MAUI frameworks..NET 10 Preview 6 was announced July 15. The production release is expected in November. Developers can download Preview 6 at dotnet.microsoft.com.

With improved code generation for struct arguments,.NET 10 Preview 6 has the JIT compiler now able to place promoted members of struct arguments into shared registers. The compiler also offers improved loop inversion in the preview, a transformation that moves the condition to the bottom of the loop to improve code layout. Numerous optimizations like loop cloning and loop unrolling depend on loop inversion, Microsoft said.

With one-shot tool exaction, developers now can use the dotnet tool exec command to execute a.NET tool without installing it locally or globally. This is especially valuable for CI/CD or ephemeral usage, according to Microsoft.

Also featured in.NET 10 Preview 6 is an option to disallow JSON properties, tending to an issue in which the JSON specification does not specify how to handle duplicate properties when deserializing a JSON payload, which can lead to security vulnerabilities and unexpected results..NET 10 Preview 6 follows.NET 10 Preview 5, which was unveiled June 10 and featured C# 14 and runtime enhancements. The first preview was announced February 25, followed by a second preview on March 18, a third preview on April 10, and a fourth preview on May 13.

Other improvements in.NET 10 Preview 6:.NET tools now can be published with support for multiple RuntimeIdentifiers (RIDs) in a single package. Tool authors can bundle binaries for supported platforms, and the.NET CLI will select the correct one at install or run time. This makes cross-platform tool authoring and distribution much easier, Microsoft said.

A new option, --cli-schema, is available on CLI commands. When used, the option outputs a JSON representation of the CLI command tree for the invoked command or subcommand. This is useful for shell integration, tool authors, and advanced scripting.

File-based apps now support being published to native executables via the dotnet publish app.cs command. This makes it easier to create simple apps that can be redistributed as native executables.

Blazor now provides a component that generates link tags for preloading framework assets instead of using link headers. This offers better control over WebAssembly preloading behavior and correctly identifies the application’s base URL. Also, Blazor now supports validating nested objects and collection items in forms.

For Windows Presentation Foundation (WPF), the Fluent theme has been improved, with capabilities such as a Fluent style for GridView.

Quality improvements were made to Entity Framework, along with a focus on build performance.

Windows Forms has improvements to dark mode support such as ListView ColumnHeaders now rendering correctly in dark mode.

New security APIs were introduced to protect forms containing sensitive information from the usual screen capture approaches.