Rebuild fails when project with multiple TFMs references Source Code-only Nuget package

Issue Description

• I have a csproj that targets both net48 and net6.0
• It also references a Source-code only nuget package (AddUp.AnyLog in this example, but reproduced with other similar packages)
• If I rebuild (from VS or with dotnet build --no-incremental or with MSBuild /t:Rebuild), it fails
• If I simply build, it works fine
• Note that in the single TFM case, everything works just fine.

Steps to Reproduce

• Use the attached solution: MultipleTfmsSourceOnlyRepro.zip
• Then either:
  • dotnet build .\MultipleTfmsSourceOnlyRepro.sln --no-incremental or
  • MSBuild.exe .\MultipleTfmsSourceOnlyRepro.sln /t:Rebuild or
  • Rebuild from Visual Studio 2022
• You should obtain a few CS0234 and CS0236 errors (types and namespaces that cannot be found)
  • In the VS case, I also some time after I interact with the editor get a handful of IDE1100 errors (Error reading content of source file…)
• Now, simply build the solution
• Everything is back to normal
  • and VS does not complain any more with IDE1100

Attached are also:

• The ‘rebuild’ binlog ("C:\Program Files\dotnet\sdk\6.0.402\MSBuild.dll" D:\repositories\tests\MultipleTfmsSourceOnlyRepro\MultipleTfmsSourceOnlyRepro.sln /t:Rebuild /v:diag /nologo /clp:NoSummary;Verbosity=minimal /bl): rebuild.binlog.zip
• The ‘build’ binlog ("C:\Program Files\dotnet\sdk\6.0.402\MSBuild.dll" D:\repositories\tests\MultipleTfmsSourceOnlyRepro\MultipleTfmsSourceOnlyRepro.sln /t:Build /v:diag /nologo /clp:NoSummary;Verbosity=minimal /bl): build.binlog.zip

Expected Behavior

Rebuilding the project should just work

Actual Behavior

Failures: types not found

Analysis

I’ve dug a bit in the binlogs and here are my findings:

• Because the dependency is a source-code package, a bunch of files are copied over to sub-directories of obj/Debug/<TFM>/NuGet/<Hash>/
• However, it seems those files are not passed down as input source to the Csc task in the Rebuild case.
• I’ve tracked down this to the RunProduceContentAssets target being skipped because _CleaningWithoutRebuilding is true
• Up the call stack, I have this _SdkBeforeClean target:

    <Target Name="_SdkBeforeClean">
      <PropertyGroup Condition="'$(_CleaningWithoutRebuilding)' == ''">
        <_CleaningWithoutRebuilding>true</_CleaningWithoutRebuilding>
        <EmitAssetsLogMessages>false</EmitAssetsLogMessages>
      </PropertyGroup>
    </Target>
  

• Because the property is empty or does not exist yet, it is assigned to true when obviously (I am rebuilding here), it should not.
• I didn’t dig further down, but I suspect there’s something not being set correctly in the case we rebuild a multiple-TFMs project

In the meantime, I managed to work around this by explicitly adding <_CleaningWithoutRebuilding>false</_CleaningWithoutRebuilding> in my csproj. But… This isn’t the cleanest thing to do, and I have no Idea what other impacts it may have in other places…

Versions & Configurations

• Visual Studio 2022 v17.3.6
• dotnet --version: 6.0.402
• MSBuild: 17.3.2+561848881

[rainersigwald]

That analysis is fairly convincing to me! Moving to SDK, where RunProduceContentAssets lives.

[odalet]

Well, I did find a workaround, but it’s a hack and not robust to change at all: I’m relying on the private MSBuild property _CleaningWithoutRebuilding that can be removed or have its semantics change at any time. I’d rather MSBuild provided an official (ideally documented) way to support this scenario as I expect I’m not the only one who needs this.