RID-specific self-contained .NET Core 3 app with dependency on Microsoft.NETCore.App 2.0.0 fails to run

[dsplaisted]

Repro

Build and run the following project:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp3.0</TargetFramework>
    <RuntimeIdentifier>win10-x64</RuntimeIdentifier>
    <SelfContained>false</SelfContained>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.NETCore.App" Version="2.0.0" />
  </ItemGroup>
</Project>

Expected

Project runs successfully

Actual

Project fails to run with error messages such as the following:

• A fatal error was encountered. The library 'hostpolicy.dll' required to execute the application was not found in 'C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App\3.0.0-preview9.19416.11'.

• The specified framework 'Microsoft.NETCore.App', version '3.0.0-preview9-19409-16' was not found.

The output folder also includes the following files, which come from the Microsoft.NETCore.App 2.0.0 package closure:

• apphost.exe
• hostfxr.dll
• hostpolicy.dll
• System.Private.CoreLib.dll

Details

NuGet/Home#7344 would fix this. Alternatively, we could try to use conflict resolution to exclude these extra assets. That would probably require updating the platform manifest in the targeting pack.

[dsplaisted]

Test case for this bug:

        [Fact]
        public void Apphost_pack_overrides_apphost_from_package()
        {
            var testProject = new TestProject()
            {
                Name="ApphostConflict",
                TargetFrameworks = "netcoreapp3.0",
                RuntimeIdentifier = EnvironmentInfo.GetCompatibleRid(),
                IsSdkProject = true,
                IsExe = true,
                AdditionalProperties =
                {
                    ["SelfContained"] = "false"
                }
            };

            testProject.PackageReferences.Add(new TestPackageReference("Microsoft.NETCore.App", "2.0.0"));

            var testAsset = _testAssetsManager.CreateTestProject(testProject)
                .Restore(Log, testProject.Name);

            var buildCommand = new BuildCommand(Log, testAsset.TestRoot, testProject.Name);

            buildCommand.Execute()
                .Should()
                .Pass();

            var outputDirectory = buildCommand.GetOutputDirectory(testProject.TargetFrameworks, runtimeIdentifier: testProject.RuntimeIdentifier);

            var hostExecutable = $"{testProject.Name}{Constants.ExeSuffix}";
            outputDirectory.Should().OnlyHaveFiles(new[]
            {
                hostExecutable,
                $"{testProject.Name}.dll",
                $"{testProject.Name}.pdb",
                $"{testProject.Name}.deps.json",
                $"{testProject.Name}.runtimeconfig.json",
                $"{testProject.Name}.runtimeconfig.dev.json",
            });

            new DotnetCommand(Log, Path.Combine(outputDirectory.FullName, hostExecutable))
                .Execute()
                .Should()
                .Pass();
        }