buildDotnetPackage not resolving framework

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1

Hey friends. I’m trying to get one of my employer’s C# applications building on NixOS, and I hit the following issue:

/build/redacted.sln (default targets) ->
(Build target) ->
/build/redacted.csproj (default targets) ->
/nix/store/qgbgsx3qp7vrvy9f1r46365g7yr46ry0-mono-5.20.1.27/lib/mono/xbuild/14.0/bin/Microsoft.Common.targets (GetReferenceAssemblyPaths target) ->

        /nix/store/qgbgsx3qp7vrvy9f1r46365g7yr46ry0-mono-5.20.1.27/lib/mono/xbuild/14.0/bin/Microsoft.Common.targets:  warning : Unable to find framework corresponding to the target framework moniker '.NETFramework,Version=v3.5,Profile=Client'. Framework assembly references will be resolved from the GAC, which might not be the intended behavior.

Here’s the config I’ve been tinkering with (including some commented-out stuff I’ve tried.) I have never touched C# before (and hope to never touch it again) so I’m pretty green in this area.

  pkgname = pkgs.buildDotnetPackage rec {
    baseName = "redacted";
    version = "redacted";
    src = pkgs.fetchgit {
      url = "redacted";
      rev = "redacted";
      sha256 = "redacted";
    };

    #buildInputs = [ pkgs.dotnetfx35.pkg ];
    #xBuildFlags = [
    #  "/p:TargetFrameworkProfile=v3.5"
    #];
    #patchPhase = ''
    #  substituteInPlace redacted.csproj --replace "Client" "Full"
    #'';
    #preBuild = ''
    #  export AssemblySearchPaths="${pkgs.dotnetfx35.referenceAssembly35Path}"
    #'';
    unpackPhase = ''
      #They use a monorepo
      cp -r ${src}/path/to/project/* .
      chmod -R u+w *
      #rm -rf bin
      #rm -rf obj
    '';
  };