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Guide for testing bug reproductions against locally-built MSBuild. Use this when you have a repro project and want to verify a fix works before submitting a PR.
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SOC 職業分類に基づく
Orchestrate an MSBuild release: create the tracking issue, branch, configure DARC channels and subscriptions, bump version in main, final-brand the release branch, insert into VS, and publish post-GA. Covers the full monthly release lifecycle aligned with VS shipping cadence.
Guide for migrating MSBuild tasks to multithreaded mode support, including compatibility red-team review. Use this when converting tasks to thread-safe versions, implementing IMultiThreadableTask, adding TaskEnvironment support, or auditing migrations for behavioral compatibility.
Guides struct-based COM interop in MSBuild using CsWin32 patterns. Consult when working with ComScope<T>, ComClassFactory, IComIID, IID.Get<T>(), delegate* unmanaged vtables, CoCreateInstance, or manually defining COM interfaces not in Win32 metadata (e.g. WMI IWbemLocator, IWbemServices).
Guides CsWin32 P/Invoke interop in MSBuild. Consult when working with the PInvoke class, Windows.Win32 namespaces, FEATURE_WINDOWSINTEROP, HANDLE/HMODULE/HRESULT types, BufferScope<T>, replacing [DllImport] with CsWin32, or conditioning Windows-only code for source builds.
Make .NET projects compatible with Native AOT and trimming by systematically resolving IL trim/AOT analyzer warnings. USE FOR: making projects AOT-compatible, fixing trimming warnings, resolving IL warnings (IL2026, IL2070, IL2067, IL2072, IL3050), adding DynamicallyAccessedMembers annotations, enabling IsAotCompatible. DO NOT USE FOR: publishing native AOT binaries, optimizing binary size, replacing reflection-heavy libraries with alternatives. INVOKES: no tools — pure knowledge skill.
Guide for running MSBuild unit tests efficiently. Use when running, scoping, filtering, or speeding up unit tests in this repository, or when finalizing a change with a heavier validation pass. Covers xUnit v3 + Microsoft.Testing.Platform (MTP) specifics and which `dotnet test` flags do and don't apply.
| name | use-bootstrap-msbuild |
| description | Guide for testing bug reproductions against locally-built MSBuild. Use this when you have a repro project and want to verify a fix works before submitting a PR. |
This skill guides you through testing a bug reproduction project against your locally-built MSBuild to verify a fix.
After making changes to MSBuild, you need to test them against a repro project. The "bootstrap" is a self-contained MSBuild installation built from your local changes. It includes all dependencies needed to build real projects.
Build MSBuild to create the bootstrap directory:
# Windows
.\build.cmd
# Unix/macOS
./build.sh
This creates the bootstrap at artifacts\bin\bootstrap\ with your changes.
Rerun this after making any code change. If run in the default mode, there may be some errors on subsequent builds about locked files (due to MSBuild worker node processes lingering). If so, run ./artifacts/bin/bootstrap/core/dotnet build-server shutdown.
Use the bootstrap dotnet CLI directly (preferred):
# Windows
artifacts\bin\bootstrap\core\dotnet.exe build <path-to-repro.csproj>
# Unix/macOS
./artifacts/bin/bootstrap/core/dotnet build <path-to-repro.csproj>
All of the usual command line arguments should work, including -bl to create binlogs.
If the problem is specific to the .NET Framework MSBuild.exe that is used in Visual Studio, and you're running on Windows, you can use the bootstrap MSBuild.exe directly:
artifacts\bin\bootstrap\net472\MSBuild\Current\Bin\MSBuild.exe <path-to-repro.csproj>
Note: The .NET Framework bootstrap output will only be complete when built on Windows using MSBuild.exe.
artifacts\bin\bootstrap\core\sdk\*\MSBuild.dll timestamp./artifacts/bin/bootstrap/core/dotnet build-server shutdown
# Or use the helper function after sourcing msbuild-build-env.ps1
killdotnet
Your fix is working! The repro uses your local changes while the installed MSBuild has the bug.
| Scenario | Command |
|---|---|
| Build bootstrap | .\build.cmd |
| .NET Core repro | artifacts\bin\bootstrap\core\dotnet.exe build <project> |
| .NET Framework repro | artifacts\bin\bootstrap\net472\MSBuild\Current\Bin\MSBuild.exe <project> |