Projects that override GetTargetPath have outputs ignored in referencing projects

[agr]

MSBuild version 15.3.255.36604 (Bundled with the VS 2017 15.3.0 Preview 2.0 [26605.1.d15rel]).
Fails to build the following project: https://github.com/NuGet/NuGet.Jobs
The same project builds fine with the MSBuild 15.1.1012.6693 (bundled with VS2017 15.2 (26430.12)).

Steps:

1. mkdir NuGet.Jobs
2. cd NuGet.Jobs
3. git clone https://github.com/NuGet/NuGet.Jobs.git .
4. git checkout dev
5. Restore nuget packages (pick one of two):
   • build.cmd (tries to restore nuget packages, then build)
   • nuget restore NuGet.Jobs.sln (needs nuget.exe present)
6. "C:\Program Files (x86)\Microsoft Visual Studio\Preview\Enterprise\MSBuild\15.0\bin\msbuild.exe" .\NuGet.Jobs.sln (msbuild paths may vary)

The first error produced:

Tests.Logger.Job.cs(9,7): error CS0246: The type or namespace name 'NuGet' could not be found (are you missing a using directive or an assembly reference?) [E:\dev\Nuget.Jobs\src\Tests.Logger\Tests.AzureJobTraceListener.csproj]

src\Tests.Logger\Tests.AzureJobTraceListener.csproj references the src\NuGet.Jobs.Common\NuGet.Jobs.Common.csproj which declares the NuGet namespace the compiler complains about, so there shouldn't be any error.

Further examination of the command line it uses to compile the Tests.AzureJobTraceListener.csproj indicates that NuGet.Jobs.Common.dll is not passed as a /reference to the csc.exe. I'm not sure how to dig deeper from this point.

msbuild.log.zip from the build produced with the /flp:v=diag command line argument.

[rainersigwald]

Thanks for the report!

This appears to be happening because Microsoft.Bcl.Build.targets overrides the GetTargetPath target, which computes the TargetPathWithTargetPlatformMoniker item. #2039 changed the Build target to return that item, rather than the metadata-free $(TargetPath). This causes projects that use the targets from Microsoft.Bcl.Build to have no value returned from the Build target, so projects that reference them don't actually reference the produced assembly.

Workaround

Add this to the bottom of any project that refers to Microsoft.Bcl.Build, just before </Project>:

   <!-- Work around https://github.com/Microsoft/msbuild/issues/2183 remove after VS 15.3 is released -->
   <Target
        Name="Build"
        Condition=" '$(_InvalidConfigurationWarning)' != 'true' "
        DependsOnTargets="$(BuildDependsOn)"
        Returns="$(TargetPath)" />

[rainersigwald]

FYI @jcouv -- another regression from ref assemblies 😞

FYI @terrajobst -- 15.3 preview 2 will break consumers of https://www.nuget.org/packages/Microsoft.Bcl.Build but a workaround is available.