Implements struct-based COM interop in MSBuild using CsWin32 patterns without built-in marshalling.
npx skills add https://github.com/dotnet/dotnet --skill cswin32-com
Please help me install this Agent Skill. Skill: cswin32-com Source: https://github.com/dotnet/dotnet/tree/main/src/msbuild/.github/skills/cswin32-com Command: npx skills add https://github.com/dotnet/dotnet --skill cswin32-com
Migrating MSBuild's COM interop away from [ComImport] and built-in marshalling to AOT-compatible, struct-based CsWin32 patterns requires precise knowledge of vtable layouts, lifetime management, and error-handling parity that is easy to get wrong.
delegate* unmanaged[Stdcall] vtable slots and dual-target IComIID shapes for net472 and .NET.ComScope<T> for transient pointers, using BSTR for COM strings, and AgileComPointer<T> for pointers stored in class fields, preventing leaks and apartment-agility hazards.[ComImport], and bridges managed mocks to struct-based COM via CCW pointers from Marshal.GetComInterfaceForObject.ComClassFactory.TryCreate, and scope every pointer correctly.Ask the assistant to define a manual CsWin32 COM struct for the WMI IWbemLocator interface with proper ComScope lifetime handling and AOT-compatible activation.
High-intent search queries and answers about installing and using this skill.
Define a manual struct implementing IComIID in its own folder, with a private void** _lpVtbl field and delegate* unmanaged[Stdcall] casts for each vtable slot. Exclude it from source builds via Compile Remove, and spell out both the static-abstract and instance IComIID shapes for dual-targeting.
Use ComScope<T> with a using declaration for every transient COM pointer from CoCreateInstance, QueryInterface, or enumerators; it Releases on dispose and implicitly converts to T** for out-params. For pointers stored in class fields, use AgileComPointer<T>, which registers in the Global Interface Table.
Yes, by bridging through the built-in COM marshaller: the mock implements the managed interface and the test passes a CCW pointer from Marshal.GetComInterfaceForObject to the struct-based API. The mock must write all out-params and throw COMException rather than assert, since exception identity is lost across the boundary.
Yes, but IComIID has two shapes: static-abstract on .NET 7+ and instance-based on net472/netstandard2.0. Manual structs must implement both arms with #if NET, while CsWin32-generated structs pick the correct shape automatically since version 0.3.287.
Struct-based COM returns raw HRESULTs instead of throwing automatically, so each call site must explicitly call ThrowOnFailure or branch on the HRESULT. When the top-level caller swallows COMException, helpers should return default or false instead of throwing exceptions that are immediately discarded.
marcosd4hReconstruct COM/WRL interface metadata from IDA Pro decompiled binaries.
dotnetTest bug repro projects against a locally-built MSBuild bootstrap.
dotnetGenerate C# P/Invoke signatures for native C/C++ libraries.
AGIBuildPublish .NET 8+ applications with Native AOT compilation and size optimizations.