投稿

[YexuanXiao]

C++/WinRT 发布了第一个支持 C++20 模块的版本（我设计的 C++/WinRT 模块支持，微软的维护的人重新按我的原型实现了一遍）https://github.com/microsoft/cppwinrt/releases/tag/3.0.260520.1 。

[YexuanXiao]

另外他也提供了一个现实的案例来说明预编译头项目改成模块的效果，注意这个现实案例的模块化是非常粗糙的，只是机械的改成模块而没有任何其他构建时间的改造，因此还有非常大的改进潜力：

This brings potential improvements in build speed, disk space, and memory usage, particularly for large projects using Xaml projections, and starts to isolate more of the internal C++/WinRT implementation details from the consumer side. Test-driving this work on a quick and dirty prototype fork of Windows Terminal yielded a 10-15% build speed improvement (22 minutes before, 19 minutes after), and a reduction in disk space from 30GB down to 18GB.

If you've ever used C++/WinRT with Windows.UI.Xaml., you've probably moved those headers into your precompiled header (PCH), but then saw your PCH consume well upwards of 1-2GB of disk space per vcxproj, per flavor. In the Terminal prototype, taking these headers out of the PCH and replacing them with a single cppwinrt module, built once and shared between projects, the PCHs shrunk by upwards of 80%, and the time to build each PCH went from ~40 seconds down to ~5 seconds. The single prebuilt cppwinrt modules carried all of the types for the entire Windows. namespaces and WinUI, and still consumed only 700MB, and took ~80-90 seconds to build. Excluding unused namespaces from the module build can lower those numbers even further. The Terminal prototype didn't do this, and still enjoyed immediate wins on disk space, and the build time wins broke even after converting about 2-3 projects out of the ~15 or so that use C++/WinRT.