MSBuild evaluation fails with "System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1" not found

[AArnott]

My unit tests which use the MSBuildLocator started failing recently when MSBuild 16.7 came out with the failure below.

The Microsoft.Build.dll that is loaded by MSBuildLocator has System.Runtime.CompilerServices.Unsafe, Version=4.0.6.0 next to it. I don't have any version of that assembly in my test output directory. Shouldn't the MSBuildLocator's assembly resolver find all of the msbuild's dependencies including this one?

  Error Message:
   System.IO.FileNotFoundException : Could not load file or assembly 'System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
  Stack Trace:
     at System.MemoryExtensions.AsSpan(String text)
   at Microsoft.Build.Evaluation.Expander`2.Function`1.ExtractPropertyFunction(String expressionFunction, IElementLocation elementLocation, Object propertyValue, UsedUninitializedProperties usedUnInitializedProperties, IFileSystem fileSystem)
   at Microsoft.Build.Evaluation.Expander`2.PropertyExpander`1.ExpandPropertyBody(String propertyBody, Object propertyValue, IPropertyProvider`1 properties, ExpanderOptions options, IElementLocation elementLocation, UsedUninitializedProperties usedUninitializedProperties, IFileSystem fileSystem)
   at Microsoft.Build.Evaluation.Expander`2.PropertyExpander`1.ExpandPropertiesLeaveTypedAndEscaped(String expression, IPropertyProvider`1 properties, ExpanderOptions options, IElementLocation elementLocation, UsedUninitializedProperties usedUninitializedProperties, IFileSystem fileSystem)
   at Microsoft.Build.Evaluation.Expander`2.PropertyExpander`1.ExpandPropertiesLeaveEscaped(String expression, IPropertyProvider`1 properties, ExpanderOptions options, IElementLocation elementLocation, UsedUninitializedProperties usedUninitializedProperties, IFileSystem fileSystem)
   at Microsoft.Build.Evaluation.Expander`2.ExpandIntoStringLeaveEscaped(String expression, ExpanderOptions options, IElementLocation elementLocation)
   at Microsoft.Build.Evaluation.ToolsetReader.ExpandPropertyUnescaped(ToolsetPropertyDefinition property, Expander`2 expander)
   at Microsoft.Build.Evaluation.ToolsetReader.EvaluateAndSetProperty(ToolsetPropertyDefinition property, PropertyDictionary`1 properties, PropertyDictionary`1 globalProperties, PropertyDictionary`1 initialProperties, Boolean accumulateProperties, String& toolsPath, String& binPath, Expander`2& expander)
   at Microsoft.Build.Evaluation.ToolsetReader.ReadToolset(ToolsetPropertyDefinition toolsVersion, PropertyDictionary`1 globalProperties, PropertyDictionary`1 initialProperties, Boolean accumulateProperties)
   at Microsoft.Build.Evaluation.ToolsetReader.ReadEachToolset(Dictionary`2 toolsets, PropertyDictionary`1 globalProperties, PropertyDictionary`1 initialProperties, Boolean accumulateProperties)
   at Microsoft.Build.Evaluation.ToolsetReader.ReadToolsets(Dictionary`2 toolsets, PropertyDictionary`1 globalProperties, PropertyDictionary`1 initialProperties, Boolean accumulateProperties, String& msBuildOverrideTasksPath, String& defaultOverrideToolsVersion)
   at Microsoft.Build.Evaluation.ToolsetReader.ReadAllToolsets(Dictionary`2 toolsets, ToolsetRegistryReader registryReader, ToolsetConfigurationReader configurationReader, PropertyDictionary`1 environmentProperties, PropertyDictionary`1 globalProperties, ToolsetDefinitionLocations locations)
   at Microsoft.Build.Evaluation.ProjectCollection.InitializeToolsetCollection(ToolsetRegistryReader registryReader, ToolsetConfigurationReader configReader)
   at Microsoft.Build.Evaluation.ProjectCollection..ctor(IDictionary`2 globalProperties, IEnumerable`1 loggers, IEnumerable`1 remoteLoggers, ToolsetDefinitionLocations toolsetDefinitionLocations, Int32 maxNodeCount, Boolean onlyLogCriticalEvents, Boolean loadProjectsReadOnly)
   at Microsoft.Build.Evaluation.ProjectCollection..ctor()
   at BuildIntegrationTests.Init() in D:\git\Nerdbank.GitVersioning\src\NerdBank.GitVersioning.Tests\BuildIntegrationTests.cs:line 64
   at BuildIntegrationTests..ctor(ITestOutputHelper logger) in D:\git\Nerdbank.GitVersioning\src\NerdBank.GitVersioning.Tests\BuildIntegrationTests.cs:line 55

[jairbubbles]

Same issue on my side. It's not pretty but adding an AssemblyResolve seems to work:

AppDomain.CurrentDomain.AssemblyResolve += (s, e) =>
{
  var filePath = Path.Combine(latestInstance.MSBuildPath, $"{new AssemblyName(e.Name).Name}.dll");
  if (File.Exists(filePath))
  {
    return Assembly.LoadFrom(filePath);
  }
  return null;
};

Please note that depending on the version of Microsoft.Build package used and the msbuild.exe targetted I have also seen different errors involving System.Collections.Immutable.dll, System.IO.Compression.dll or System.Memory.

[Forgind]

Was this fixed by #94?

[jairbubbles]

I think I tested the pre-release version that should have contained the fix and I still had issues. It might have been on different assembly though.

Why do we keep a fixed list of MsBuild assemblies? Why don't we just load if it's found in the MsBuild directory? It seems more future-proof to me.

[Forgind]

Why do we keep a fixed list of MsBuild assemblies? Why don't we just load if it's found in the MsBuild directory? It seems more future-proof to me.

A very reasonable question. I can imagine it would be worse for perf, since a lot of that stuff isn't really MSBuild's, but I doubt that would be a huge factor, and it would certainly be more convenient and future-proof. I put a change here. We'll see how it goes. 🙂

[Forgind]

107 was merged, though it isn't in the NuGet package yet. Does that work?

[AArnott]

@forgind: No.

I locally built master (d007e5e6f7) and tested it against my original repro (https://github.com/dotnet/Nerdbank.GitVersioning.git 0f97225) and ran the AssemblyInfo test. The error changed from a missing Unsafe dll to this one:

  Message: 
    System.AggregateException : A directory or directories in "msbuildSearchPaths" do not exist
  Stack Trace: 
    MSBuildLocator.RegisterMSBuildPath(String[] msbuildSearchPaths)
    MSBuildLocator.RegisterMSBuildPath(String msbuildPath)
    MSBuildLocator.RegisterInstance(VisualStudioInstance instance)
    MSBuildLocator.RegisterDefaults()
    MSBuildExtensions.LoadMSBuild() line 26
    MSBuildFixture.ctor() line 5

[Forgind]

I think that error has now been fixed.

[AArnott]

Confirmed. As of 23fb66e50a36d6 the test passes now.