Problem

When building and packing the MVVM SourceGenerator projects, pack fails to find the output artifacts when we use custom output paths. This is observed in #96 when I tried to use a common output path for building the entire solution. I could update the current method to find the artifacts but it feels hacky and not integrated with the build pipeline.

Thus, any change like changing the output paths not just in the build definition but also changing via terminal invocation (say dotnet build -o path_to_out_dir) will definitely break the build and it won't pack those files. Worst of all, sometimes, the build pipeline won't fail. So, we won't know if the MVVM package was properly packed.

To Reproduce

1. Clone the repo or clean it
   git clean -Xdf
2. Build MVVM SourceGenerator project (with a different output path).
   dotnet build CommunityToolkit.Mvvm.SourceGenerators -o bin_dir
3. Pack the MVVM project (with a different output path).
   dotnet pack CommunityToolkit.Mvvm -o pkg_dir

Result

Solution

Get the build outputs dynamically via GetBuildOutputs MSBuild target mirroring NuGet's Pack targets and add it to pack via _PackageFiles internal MSBuild item used by NuGet's Pack targets. This is brittle only if @NuGet team decides to modify/remove _PackageFiles which is highly unlikely.

One interesting side-effect of this implementation is that when we decide to multi-target, we can easily modify our solution to be more resilient without having to tackle the problem again since we already output the artifacts by TFM. This should save hours of headbutting against the wall 😉!!