The cswinrt folder
Contains the sources and cswinrt.vcxproj project file for building the C#/WinRT compiler, cswinrt.exe. The projection's base library is contained in /cswinrt/strings/WinRT.cs, which is processed by /strings.props to generate string literals contained in the compiler.
The compiler uses the WinMD NuGet package for parsing ECMA-335 metadata files. The WinMD github repo includes a winmd.natvis script for debugging metadata parsing. A symlink can be used to install the script:
for /f "tokens=2*" %i in ('reg query "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" /v Personal ^| findstr Personal') do @for /f "tokens=2" %k in ('"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere" -latest ^| findstr catalog_productLineVersion') do @echo %j\Visual Studio %k\Visualizers| for /f "delims=" %l in ('more') do @md "%l" 2>nul & mklink "%l\winmd.natvis" "c:\git\winmd\vs\winmd.natvis"
The C#/WinRT project also contains a cswinrt.natvis script for debugging the C# projection writing, which can also be installed with a symlink:
for /f "tokens=2*" %i in ('reg query "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders" /v Personal ^| findstr Personal') do @for /f "tokens=2" %k in ('"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere" -latest ^| findstr catalog_productLineVersion') do @echo %j\Visual Studio %k\Visualizers| for /f "delims=" %l in ('more') do @md "%l" 2>nul & mklink "%l\cswinrt.natvis" "c:\git\cswinrt\cswinrt\cswinrt.natvis"
See also Deploying .natvis files.
The WinRT.Runtime folder
Contains the WinRT.Runtime project for building the C#/WinRT runtime assembly, winrt.runtime.dll. There are two versions of this assembly, providing an abstraction layer over both .NET Standard 2.0 and .NET 5 runtimes. While all code generated by cswinrt.exe is compatible with .NET Standard 2.0, there are runtime differences which must be addressed. The primary difference is that the .NET 5 winrt.runtime.dll provides Xaml reference tracking support, which is necessary for WinUI 3 applications to manage memory correctly. Future performance enhancements, such as function pointer support, may also be limited to the .NET 5 winrt.runtime.dll.
The nuget folder
Contains source files for producing a C#/WinRT NuGet package, which is regularly built, signed, and published to nuget.org by Microsoft. The C#/WinRT NuGet package contains the cswinrt.exe compiler, and both versions of the winrt.runtime.dll.
C#/WinRT makes use of the standalone TestWinRT repository for general language projection test coverage. This repo should be cloned into the root of the C#/WinRT repo, via get_testwinrt.cmd, so that the cswinrt.sln can resolve its reference to TestComponent.vcxproj. The resulting TestComponent.dll and TestComponent.winmd files are consumed by the UnitTest project above.
The TestComponentCSharp folder
Contains an implementation of a WinRT test component, defined in class.idl and used by the UnitTest project. To complement the general TestComponent above, the TestComponentCSharp tests scenarios specific to the C#/WinRT language projection.
The Projections folder
Contains several projects for generating and building projections from the Windows SDK, WinUI, Benchmark (produced by the BenchmarkComponent project), and Test metadata (produced by the TestWinRT and TestComponentCSharp projects).
The UnitTest folder
Contains unit tests for validating the Windows SDK, WinUI, and Test projections generated above. All pull requests should ensure that this project executes without errors.
The Benchmarks folder
Contains benchmarks written using BenchmarkDotNet to track the performance of scenarios in the generated projection. To run the benchmarks using the CsWinRT projection, run benchmark.cmd. To run the same benchmarks using the built-in WinMD support in NET Core 3.1 to compare against as a baseline, run benchmark_winmd.cmd.
The WinUIDesktopSample folder
Contains an end-to-end sample app that uses the Windows SDK and WinUI projections generated above.