Sitecore namespace not found when referencing v8.0 packages via NuGet

Question

I have a clean VS 2019 project targeting .NET Framework 4.5 referencing Sitecore.Kernel and Sitecore.ContentSearch packages (specifically v8.0.150812) via NuGet using PackageReference. However, I get build errors in that the Sitecore types or namespaces cannot be found.

This is the project file:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net45</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Sitecore.ContentSearch" Version="8.0.150812">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Sitecore.Kernel" Version="8.0.150812">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
  </ItemGroup>
  <ItemGroup>
    <Reference Include="System" />
    <Reference Include="System.Core" />
    <Reference Include="System.Xml.Linq" />
    <Reference Include="System.Data.DataSetExtensions" />
    <Reference Include="Microsoft.CSharp" />
    <Reference Include="System.Data" />
    <Reference Include="System.Net.Http" />
    <Reference Include="System.Xml" />
  </ItemGroup>
</Project>

This is my class:

using Sitecore.ContentSearch;
using Sitecore.ContentSearch.SearchTypes;

namespace TheValley.Sc.Modules.Search.SearchTypes
{
    public class CustomSearchResultItem : SearchResultItem
    {
        [IndexField("_foo")]
        public string Foo { get; set; }
    }
}

This is what I see in Solution Explorer:

This is the build output:

CustomSearchResultItem.cs(1,7,1,15): error CS0246: The type or namespace name 'Sitecore' could not be found (are you missing a using directive or an assembly reference?) CustomSearchResultItem.cs(2,7,2,15): error CS0246: The type or namespace name 'Sitecore' could not be found (are you missing a using directive or an assembly reference?) CustomSearchResultItem.cs(6,43,6,59): error CS0246: The type or namespace name 'SearchResultItem' could not be found (are you missing a using directive or an assembly reference?) CustomSearchResultItem.cs(8,10,8,20): error CS0246: The type or namespace name 'IndexFieldAttribute' could not be found (are you missing a using directive or an assembly reference?) CustomSearchResultItem.cs(8,10,8,20): error CS0246: The type or namespace name 'IndexField' could not be found (are you missing a using directive or an assembly reference?)

It is necessary for me to reference Sitecore 8.0 packages. No other restrictions. Any assistance greatly appreciated.

Answer 1

I recreated the project from scratch on another system, and for some as-yet-unknown reason, the PrivateAssets and IncludeAssets elements were not added when I added the Sitecore package references, and the project built successfully.

I then proceeded to remove these elements from my original project, and it then also built successfully. So, this appears to be the problem. It may not be Sitecore-specific as this solution was also the case for a similar issue here. A bug in the "weaver"?

So, the solution is just to remove the PrivateAssets and IncludeAssets elements from the PackageReference nodes in the project file.