Microsoft.Build.Traversal does not respect SetPlatform or AdditionalProperties on ProjectReference items

[forrestcoward]

The Microsoft.Build.Traversal SDK does not respect SetPlatform, SetConfiguration or AdditionalProperties on ProjectReference items, it ignores them, effectively losing the metadata. It is customary for global properties to propagate along ProjectReference.

Here is the location I am looking at that is offending:
https://github.com/microsoft/MSBuildSdks/blob/master/src/Traversal/Sdk/Sdk.targets#L123-L136

  <Target Name="Build"
          DependsOnTargets="$(BuildDependsOn)"
          Condition=" '$(IsGraphBuild)' != 'true' "
          Returns="@(CollectedBuildOutput)">
    <MSBuild Projects="@(ProjectReference)"
             Condition="'%(ProjectReference.Build)' != 'false'"
             BuildInParallel="$([MSBuild]::ValueOrDefault('%(ProjectReference.BuildInParallel)', '$(BuildInParallel)'))"
             SkipNonexistentProjects="$(SkipNonexistentProjects)"
             SkipNonexistentTargets="$(SkipNonexistentTargets)"
             StopOnFirstFailure="$(StopOnFirstFailure)"
             ContinueOnError="$(ContinueOnError)">
      <Output TaskParameter="TargetOutputs" ItemName="CollectedBuildOutput" />
    </MSBuild>
  </Target>

The solution is something like this:

  <Target Name="Build"
          DependsOnTargets="$(BuildDependsOn)"
          Condition=" '$(IsGraphBuild)' != 'true' "
          Returns="@(CollectedBuildOutput)">
    <MSBuild Projects="@(ProjectReference)"
             Condition="'%(ProjectReference.Build)' != 'false'"
             BuildInParallel="$([MSBuild]::ValueOrDefault('%(ProjectReference.BuildInParallel)', '$(BuildInParallel)'))"
             Properties="%(ProjectReference.SetConfiguration); %(ProjectReference.SetPlatform); %(ProjectReference.AdditionalProperties)"
             SkipNonexistentProjects="$(SkipNonexistentProjects)"
             SkipNonexistentTargets="$(SkipNonexistentTargets)"
             StopOnFirstFailure="$(StopOnFirstFailure)"
             ContinueOnError="$(ContinueOnError)">
      <Output TaskParameter="TargetOutputs" ItemName="CollectedBuildOutput" />
    </MSBuild>
  </Target>

Note the addition of Properties attribute.

Why is this needed? Anybody setting properties on their ProjectReference lose them when using the traversal SDK. In my case, these properties are valuable.

[forrestcoward]

If this seems reasonable, I can just PR it in.

[jeffkl]

Sounds like a good change, there's another property SetTargetFramework

https://github.com/dotnet/msbuild/blob/master/src/Tasks/Microsoft.Common.CurrentVersion.targets#L1855

But I think AdditionalProperties does get passed through.

https://github.com/dotnet/msbuild/blob/master/src/Tasks/MSBuild.cs#L543-L553

[forrestcoward]

You're right, it looks like AdditionalProperties is getting passed through! I just verified. So it seems we just need SetTargetFramework, SetPlatform, and SetConfiguration?

[jeffkl]

Yes just those 3 properties to mirror the logic used in ResolveProjectReferences. Please send a PR!

[tmds]

@forrestcoward @jeffkl how do I pass variables like Configuration downstream?

I tried setting Configuration to Release like this:

<Project Sdk="Microsoft.Build.Traversal/3.0.2">
	<PropertyGroup>
		<Configuration>Release</Configuration>
	</PropertyGroup>
	<ItemGroup>
		<ProjectReference Include="console/console.csproj"/>
	</ItemGroup>
</Project>

but it doesn't get applied to the ProjectReference:

$ dotnet build
Microsoft (R) Build Engine version 16.8.0-preview-20414-02+a55ce4fbb for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
  All projects are up-to-date for restore.
  You are using a preview version of .NET. See: https://aka.ms/dotnet-core-preview
  console -> /tmp/root/console/bin/Debug/net5.0/console.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:01.33

[jeffkl]

@tmds you'll need to add the metadata to the ProjectReference to opt into this behavior:

<ItemGroup>
    <ProjectReference Include="console/console.csproj" SetConfiguration="Configuration=$(Configuration)"/>
</ItemGroup>

Or you can set it as a global property:

msbuild /Property:Configuration=Release